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Bibliography on: Symbiosis

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ESP: PubMed Auto Bibliography 26 Mar 2019 at 01:48 Created: 

Symbiosis

Symbiosis refers to an interaction between two or more different organisms living in close physical association, typically to the advantage of both. Symbiotic relationships were once thought to be exceptional situations. Recent studies, however, have shown that every multicellular eukaryote exists in a tight symbiotic relationship with billions of microbes. The associated microbial ecosystems are referred to as microbiome and the combination of a multicellular organism and its microbiota has been described as a holobiont. It seems "we are all lichens now."

Created with PubMed® Query: symbiosis NOT pmcbook NOT ispreviousversion

Citations The Papers (from PubMed®)

RevDate: 2019-03-25

Uchi N, Fukudome M, Nozaki N, et al (2019)

Antimicrobial Activities of Cysteine-rich Peptides Specific to Bacteriocytes of the Pea Aphid Acyrthosiphon pisum.

Microbes and environments [Epub ahead of print].

Aphids have a mutualistic relationship with the bacterial endosymbiont Buchnera aphidicola. We previously reported seven cysteine-rich peptides in the pea aphid Acyrthosiphon pisum and named them Bacteriocyte-specific Cysteine-Rich (BCR) peptides; these peptides are exclusively expressed in bacteriocytes, special aphid cells that harbor symbionts. Similar symbiotic organ-specific cysteine-rich peptides identified in the root nodules of leguminous plants are named Nodule-specific Cysteine-Rich (NCR) peptides. NCR peptides target rhizobia in the nodules and are essential for symbiotic nitrogen fixation. A BacA (membrane protein) mutant of Sinorhizobium is sensitive to NCR peptides and is unable to establish symbiosis. Based on the structural and expressional similarities between BCR peptides and NCR peptides, we hypothesized that aphid BCR peptides exhibit antimicrobial activity, similar to some NCR peptides. We herein synthesized BCR peptides and investigated their antimicrobial activities and effects on the bacterial membrane of Escherichia coli. The peptides BCR1, BCR3, BCR5, and BCR8 exhibited antimicrobial activities with increased membrane permeability. An sbmA mutant of E. coli, a homolog of bacA of S. meliloti, was more sensitive to BCR peptides than the wild type. Our results suggest that BCR peptides have properties that may be required to control the endosymbiont, similar to NCR peptides in legumes.

RevDate: 2019-03-25

Bartolomaeus H, Markó L, Wilck N, et al (2019)

Precarious Symbiosis Between Host and Microbiome in Cardiovascular Health.

Hypertension (Dallas, Tex. : 1979) [Epub ahead of print].

RevDate: 2019-03-23

Kord H, Fakheri B, Ghabooli M, et al (2019)

Salinity-associated microRNAs and their potential roles in mediating salt tolerance in rice colonized by the endophytic root fungus Piriformospora indica.

Functional & integrative genomics pii:10.1007/s10142-019-00671-6 [Epub ahead of print].

Piriformospora indica (P. indica), an endophytic root fungus, supports the growth and enhanced tolerance of plants to biotic and abiotic stresses. Several recent studies showed the significant role of small RNA (sRNA) molecules including microRNAs (miRNAs) in plant adaption to environmental stress, but little is known concerning the symbiosis-mediated salt stress tolerance regulated at miRNAs level. The overarching goal of this research is to elucidate the impact of miRNAs in regulating the P. indica-mediated salt tolerance in rice. Applying sRNA-seq analysis led to identify a set of 547 differentially abundant miRNAs in response to P. indica inoculation and salt stress. These included 206 rice-specific and 341 previously known miRNAs from other plant species. In silico analysis of miRNAs predictions of the differentially abundant miRNAs led to identifying of 193 putatively target genes, most of which were encoded either genes or transcription factors involved in nutrient uptake, sodium ion transporters, growth regulators, and auxin- responsive proteins. The rice-specific miRNAs targeted the transcription factors involved in the import of potassium ions into the root cells, the export of sodium ions, and plant growth and development. Interestingly, P. indica affected the differential abundance of miRNAs regulated genes and transcription factors linked to salt stress tolerance. Our data helps to understand the molecular basis of salt stress tolerance mediated by symbionts in plant and the potential impact of miRNAs for genetic improvement of rice varieties for tolerance to salt stress.

RevDate: 2019-03-25
CmpDate: 2019-03-25

Strodtman KN, Frank S, Stevenson S, et al (2018)

Proteomic Characterization of Bradyrhizobium diazoefficiens Bacteroids Reveals a Post-Symbiotic, Hemibiotrophic-Like Lifestyle of the Bacteria within Senescing Soybean Nodules.

International journal of molecular sciences, 19(12): pii:ijms19123947.

The form and physiology of Bradyrhizobium diazoefficiens after the decline of symbiotic nitrogen fixation has been characterized. Proteomic analyses showed that post-symbiotic B. diazoefficiens underwent metabolic remodeling as well-defined groups of proteins declined, increased or remained unchanged from 56 to 119 days after planting, suggesting a transition to a hemibiotrophic-like lifestyle. Enzymatic analysis showed distinct patterns in both the cytoplasm and the periplasm. Similar to the bacteroid, the post-symbiotic bacteria rely on a non-citric acid cycle supply of succinate and, although viable, they did not demonstrate the ability to grow within the senescent nodule.

RevDate: 2019-03-25
CmpDate: 2019-03-25

Martin WF, JF Allen (2018)

An Algal Greening of Land.

Cell, 174(2):256-258.

Photosynthetic eukaryotes arose ∼1.5 billion years ago by endosymbiosis with a cyanobacterium. Algae then evolved for a billion years before one lineage finally colonized land. Why the wait? The Chara braunii genome details a decisive step linking plant origins with Earth's history.

RevDate: 2019-03-22

Ricks KD, RT Koide (2019)

Biotic filtering of endophytic fungal communities in Bromus tectorum.

Oecologia pii:10.1007/s00442-019-04388-y [Epub ahead of print].

The assembly of horizontally transmitted endophytic fungi within plant tissues may be affected by "biotic filtering". In other words, only particular endophytic fungal taxa from the available inoculum pool may be able to colonize a given plant species. We tested that hypothesis in Bromus tectorum, an important invasive species in the arid, western United States. We collected seed from Bromus tectorum and sources of inoculum for endophytic fungi including soil and various kinds of plant litter at a field site in central Utah. We characterized, using Illumina sequencing, the endophytic fungal communities in the various inoculum sources, inoculated Bromus tectorum seedlings under gnotobiotic conditions with the various sources, and then characterized the communities of endophytic fungi that assembled in their roots and leaves. Different inoculum sources containing significantly different endophytic fungal communities produced complex communities of endophytic fungi in leaves and roots of Bromus tectorum. In leaves, the communities assembling from the various inoculum sources were not significantly different from each other and, in roots, they were only slightly different from each other, mainly due to variation in a single fungal OTU, Coprinopsis brunneofibrillosa. Consequently, there was significantly more variation in the structure of the communities of endophytic fungi among the inoculum sources than in the resultant endophytic fungal communities in the leaves and roots of Bromus tectorum. These results are consistent with biotic filtering playing a significant role in endophytic fungal community assembly.

RevDate: 2019-03-22

Zhang D, PS Frenette (2019)

Crosstalk between neutrophils and the microbiota.

Blood pii:blood-2018-11-844555 [Epub ahead of print].

TThe microbiota has emerged as an important regulator of the host immunity by the induction, functional modulation or suppression of local and systemic immune responses. In return, the host immune system restricts translocation and fine-tunes the composition and distribution of the microbiota to maintain a beneficial symbiosis. This paradigm applies to neutrophils, a critical component of the innate immunity, allowing their production and function to be influenced by microbial components and metabolites derived from the microbiota, and engaging them in the process of microbiota containment and regulation. The crosstalk between neutrophils and the microbiota adjusts the magnitude of neutrophil-mediated inflammation upon challenge while preventing neutrophil responses against commensals under steady state. Here, we review the major molecular and cellular mediators of the interactions between neutrophils and the microbiota, and discuss their interplay and contribution in chronic inflammatory diseases and cancer.

RevDate: 2019-03-22

Dunigan DD, Al-Sammak M, Al-Ameeli Z, et al (2019)

Chloroviruses Lure Hosts through Long-Distance Chemical Signaling.

Journal of virology, 93(7): pii:JVI.01688-18.

Chloroviruses exist in aquatic systems around the planet and they infect certain eukaryotic green algae that are mutualistic endosymbionts in a variety of protists and metazoans. Natural chlorovirus populations are seasonally dynamic, but the precise temporal changes in these populations and the mechanisms that underlie them have heretofore been unclear. We recently reported the novel concept that predator/prey-mediated virus activation regulates chlorovirus population dynamics, and in the current study, we demonstrate virus-packaged chemotactic modulation of prey behavior.IMPORTANCE Viruses have not previously been reported to act as chemotactic/chemoattractive agents. Rather, viruses as extracellular entities are generally viewed as non-metabolically active spore-like agents that await further infection events upon collision with appropriate host cells. That a virus might actively contribute to its fate via chemotaxis and change the behavior of an organism independent of infection is unprecedented.

RevDate: 2019-03-22
CmpDate: 2019-03-22

Nalini S, Inbakandan D, Venkatnarayanan S, et al (2019)

PYRROLO isolated from marine sponge associated bacterium Halobacillus kuroshimensis SNSAB01 - Antifouling study based on molecular docking, diatom adhesion and mussel byssal thread inhibition.

Colloids and surfaces. B, Biointerfaces, 173:9-17.

In the present study, an attempt has been made to explore the antifouling potential of bioactive compound isolated from sponge associated bacterium Halobacillus kuroshimensis SNSAB01. The crude extract of SNSAB01 strongly inhibited the growth of fouling bacterial strains with least minimal inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The bioactive compound was characterized through FT-IR, HPLC, GCMS and NMR predicted as 'pyrrolo". From the mass spectral library, structure was elucidated as pyrrolo [1, 2-a] pyrazine-1, 4-dione, hexahydro. The in silico studies provided encouraging docking scores with two interactions by GLN 200 and GLU 304. The extract inhibited 89% diatom adhesion at 350 μg/ml concentration against Amphora sp. An EC50 value of 150 μg/ml for 50% inhibition of byssal thread of Perna viridis and LC50 was found to be 500 μg/ml. The LC50/EC50 ratio of 3.0 indicated nontoxic to nature. The result suggested that pyrrolo[1,2-a]pyrazine-1,4-dione can be used for antifouling coating.

RevDate: 2019-03-22
CmpDate: 2019-03-22

McCormick S (2018)

An arbuscular mycorrhizal fungus adjusts its secretome depending on developmental stage and host plant.

The Plant journal : for cell and molecular biology, 94(3):409-410.

RevDate: 2019-03-21

Jonnalagadda M, Ashhad Faizan M, Ozarkar S, et al (2019)

A genome-wide association study of skin and iris pigmentation among individuals of South Asian ancestry.

Genome biology and evolution pii:5416147 [Epub ahead of print].

South Asia has a complex history of migrations, and is characterized by substantial pigmentary and genetic diversity. For this reason, it is an ideal region to study the genetic architecture of normal pigmentation variation. Here, we present a meta-analysis of two GWAS of skin pigmentation using skin reflectance (M-index) as a quantitative phenotype. The meta-analysis includes a sample of individuals of South Asian descent living in Canada (N = 348), and a sample of individuals from two caste and four tribal groups from West Maharashtra, India (N = 480). We also present the first GWAS of iris color in South Asian populations. This GWAS was based on quantitative measures of iris color obtained from high resolution iris pictures. We identified genome-wide significant associations of variants within the well-known gene SLC24A5, including the non-synonymous rs1426654 polymorphism, with both skin pigmentation and iris color, highlighting the pleiotropic effects of this gene on pigmentation. Variants in the HERC2 gene (e.g. rs12913832) were also associated with iris color and iris heterochromia. Our study emphasizes the usefulness of quantitative methods to study iris color variation. We also identified novel genome-wide significant associations with skin pigmentation and iris color, but we could not replicate these associations due to the lack of independent samples. It will be critical to expand the number of studies in South Asian populations in order to better understand the genetic variation driving the diversity of skin pigmentation and iris color observed in this region.

RevDate: 2019-03-21

Tolley SJA, Nonacs P, P Sapountzis (2019)

Wolbachia Horizontal Transmission Events in Ants: What Do We Know and What Can We Learn?.

Frontiers in microbiology, 10:296.

While strict vertical transmission insures the durability of intracellular symbioses, phylogenetic incongruences between hosts and endosymbionts suggest horizontal transmission must also occur. These horizontal acquisitions can have important implications for the biology of the host. Wolbachia is one of the most ecologically successful prokaryotes in arthropods, infecting an estimated 50-70% of all insect species. Much of this success is likely due to the fact that, in arthropods, Wolbachia is notorious for manipulating host reproduction to favor transmission through the female germline. However, its natural potential for horizontal transmission remains poorly understood. Here we evaluate the fundamental prerequisites for successful horizontal transfer, including necessary environmental conditions, genetic potential of bacterial strains, and means of mediating transfers. Furthermore, we revisit the relatedness of Wolbachia strains infecting the Panamanian leaf-cutting ant, Acromyrmex echinatior, and its inquiline social parasite, Acromyrmex insinuator, and compare our results to a study published more than 15 years ago by Van Borm et al. (2003). The results of this pilot study prompt us to reevaluate previous notions that obligate social parasitism reliably facilitates horizontal transfer and suggest that not all Wolbachia strains associated with ants have the same genetic potential for horizontal transmission.

RevDate: 2019-03-21
CmpDate: 2019-03-21

Ševcíková T, Yurchenko T, Fawley KP, et al (2019)

Plastid Genomes and Proteins Illuminate the Evolution of Eustigmatophyte Algae and Their Bacterial Endosymbionts.

Genome biology and evolution, 11(2):362-379 pii:5284916.

Eustigmatophytes, a class of stramenopile algae (ochrophytes), include not only the extensively studied biotechnologically important genus Nannochloropsis but also a rapidly expanding diversity of lineages with much less well characterized biology. Recent discoveries have led to exciting additions to our knowledge about eustigmatophytes. Some proved to harbor bacterial endosymbionts representing a novel genus, Candidatus Phycorickettsia, and an operon of unclear function (ebo) obtained by horizontal gene transfer from the endosymbiont lineage was found in the plastid genomes of still other eustigmatophytes. To shed more light on the latter event, as well as to generally improve our understanding of the eustigmatophyte evolutionary history, we sequenced plastid genomes of seven phylogenetically diverse representatives (including new isolates representing undescribed taxa). A phylogenomic analysis of plastid genome-encoded proteins resolved the phylogenetic relationships among the main eustigmatophyte lineages and provided a framework for the interpretation of plastid gene gains and losses in the group. The ebo operon gain was inferred to have probably occurred within the order Eustigmatales, after the divergence of the two basalmost lineages (a newly discovered hitherto undescribed strain and the Pseudellipsoidion group). When looking for nuclear genes potentially compensating for plastid gene losses, we noticed a gene for a plastid-targeted acyl carrier protein that was apparently acquired by horizontal gene transfer from Phycorickettsia. The presence of this gene in all eustigmatophytes studied, including representatives of both principal clades (Eustigmatales and Goniochloridales), is a genetic footprint indicating that the eustigmatophyte-Phycorickettsia partnership started no later than in the last eustigmatophyte common ancestor.

RevDate: 2019-03-21

Amos BA, Hayes RA, Leemon DM, et al (2019)

Small Hive Beetle (Coleoptera: Nitidulidae) and the Yeast, Kodamaea ohmeri: A Facultative Relationship Under Laboratory Conditions.

Journal of economic entomology, 112(2):515-524.

The small hive beetle, Aethina tumida Murray, is a pest of honeybees, Apis mellifera L. (Hymenoptera: Apidae). We investigated the significance of its association with the yeast, Kodamaea ohmeri (Etchells & Bell) (Ascomycota: Saccharomycotina), in laboratory experiments. The mean (± SEM) viability of A. tumida eggs was 84 (± 3)%; the viability was not affected if eggs were separated from clutches or if mucilage containing K. ohmeri was removed from the egg surface. Life tables of conventional (= K. ohmeri contaminated) A. tumida and K. ohmeri-free A. tumida revealed no differences in stage-specific mortality between the treatments; in both cases, the highest mortality occurred in the first larval instar. There was no significant difference in the initial egg production of conventionally reared and K. ohmeri-free A. tumida under laboratory conditions. The volatile profiles of pollen dough (Bee Build) fed on by conventional and K. ohmeri-free A. tumida larvae were qualitatively and quantitatively different; the volatiles produced by pollen dough fed on by conventional A. tumida were more attractive to adult beetles. There was a clear difference between growth of K. ohmeri on pollen dough substrate in the presence and absence of A. tumida. Results suggest that this association is facultative for A. tumida under laboratory conditions but has benefit for the yeast associate, K. ohmeri. A clearer understanding of the nature of this fungus-insect association is essential for the development of management strategies for this pest, especially in the development of fermentate-based attractants in trapping systems.

RevDate: 2019-03-21
CmpDate: 2019-03-21

Zamora-Lagos MA, Eckstein S, Langer A, et al (2018)

Phenotypic and genomic comparison of Photorhabdus luminescens subsp. laumondii TT01 and a widely used rifampicin-resistant Photorhabdus luminescens laboratory strain.

BMC genomics, 19(1):854.

BACKGROUND: Photorhabdus luminescens is an enteric bacterium, which lives in mutualistic association with soil nematodes and is highly pathogenic for a broad spectrum of insects. A complete genome sequence for the type strain P. luminescens subsp. laumondii TT01, which was originally isolated in Trinidad and Tobago, has been described earlier. Subsequently, a rifampicin resistant P. luminescens strain has been generated with superior possibilities for experimental characterization. This strain, which is widely used in research, was described as a spontaneous rifampicin resistant mutant of TT01 and is known as TT01-RifR.

RESULTS: Unexpectedly, upon phenotypic comparison between the rifampicin resistant strain and its presumed parent TT01, major differences were found with respect to bioluminescence, pigmentation, biofilm formation, haemolysis as well as growth. Therefore, we renamed the strain TT01-RifR to DJC. To unravel the genomic basis of the observed differences, we generated a complete genome sequence for strain DJC using the PacBio long read technology. As strain DJC was supposed to be a spontaneous mutant, only few sequence differences were expected. In order to distinguish these from potential sequencing errors in the published TT01 genome, we re-sequenced a derivative of strain TT01 in parallel, also using the PacBio technology. The two TT01 genomes differed at only 30 positions. In contrast, the genome of strain DJC varied extensively from TT01, showing 13,000 point mutations, 330 frameshifts, and 220 strain-specific regions with a total length of more than 300 kb in each of the compared genomes.

CONCLUSIONS: According to the major phenotypic and genotypic differences, the rifampicin resistant P. luminescens strain, now named strain DJC, has to be considered as an independent isolate rather than a derivative of strain TT01. Strains TT01 and DJC both belong to P. luminescens subsp. laumondii.

RevDate: 2019-03-21
CmpDate: 2019-03-21

Dose B, Niehs SP, Scherlach K, et al (2018)

Unexpected Bacterial Origin of the Antibiotic Icosalide: Two-Tailed Depsipeptide Assembly in Multifarious Burkholderia Symbionts.

ACS chemical biology, 13(9):2414-2420.

Icosalide is an unusual two-tailed lipocyclopeptide antibiotic that was originally isolated from a fungal culture. Yet, its biosynthesis and ecological function have remained enigmatic. By genome mining and metabolic profiling of a bacterial endosymbiont (Burkholderia gladioli) of the pest beetle Lagria villosa, we unveiled a bacterial origin of icosalide. Functional analysis of the biosynthetic gene locus revealed an unprecedented nonribosomal peptide synthetase (NRPS) that incorporates two β-hydroxy acids by means of two starter condensation domains in different modules. This unusual assembly line, which may inspire new synthetic biology approaches, is widespread among many symbiotic Burkholderia species from diverse habitats. Biological assays showed that icosalide is active against entomopathogenic bacteria, thus adding to the chemical armory protecting beetle offspring. By creating a null mutant, we found that icosalide is a swarming inhibitor, which may play a role in symbiotic interactions and bears the potential for therapeutic applications.

RevDate: 2019-03-21
CmpDate: 2019-03-21

Bag S, Ghosh TS, Banerjee S, et al (2019)

Molecular Insights into Antimicrobial Resistance Traits of Commensal Human Gut Microbiota.

Microbial ecology, 77(2):546-557.

Antimicrobial resistance (AMR) among bacterial species that resides in complex ecosystems is a natural phenomenon. Indiscriminate use of antimicrobials in healthcare, livestock, and agriculture provides an evolutionary advantage to the resistant variants to dominate the ecosystem. Ascendency of resistant variants threatens the efficacy of most, if not all, of the antimicrobial drugs commonly used to prevent and/or cure microbial infections. Resistant phenotype is very common in enteric bacteria. The most common mechanisms of AMR are enzymatic modifications to the antimicrobials or their target molecules. In enteric bacteria, most of the resistance traits are acquired by horizontal gene transfer from closely or distantly related bacterial population. AMR traits are generally linked with mobile genetic elements (MGEs) and could rapidly disseminate to the bacterial species through horizontal gene transfer (HGT) from a pool of resistance genes. Although prevalence of AMR genes among pathogenic bacteria is widely studied in the interest of infectious disease management, the resistance profile and the genetic traits that encode resistance to the commensal microbiota residing in the gut of healthy humans are not well-studied. In the present study, we have characterized AMR phenotypes and genotypes of five dominant commensal enteric bacteria isolated from the gut of healthy Indians. Our study revealed that like pathogenic bacteria, enteric commensals are also multidrug-resistant. The genes encoding antibiotic resistance are physically linked with MGEs and could disseminate vertically to the progeny and laterally to the distantly related microbial species. Consequently, the AMR genes present in the chromosome of commensal gut bacteria could be a potential source of resistance functions for other enteric pathogens.

RevDate: 2019-03-21
CmpDate: 2019-03-21

Miranda V, Rothen C, Yela N, et al (2019)

Subterranean Desert Rodents (Genus Ctenomys) Create Soil Patches Enriched in Root Endophytic Fungal Propagules.

Microbial ecology, 77(2):451-459.

Subterranean rodents are considered major soil engineers, as they can locally modify soil properties by their burrowing activities. In this study, the effect of a subterranean rodent of the genus Ctenomys on soil properties and root endophytic fungal propagules in a shrub desert of northwest Argentina was examined. Our main goal was to include among root endophytic fungi not only arbuscular mycorrhiza but also the dark septate endophytes. We compared the abundance of fungal propagules as well as several microbiological and physicochemical parameters between soils from burrows and those from the surrounding landscape. Our results show that food haulage, the deposition of excretions, and soil mixing by rodents' burrowing promote soil patchiness by (1) the enrichment in both types of root endophytic fungal propagules; (2) the increase in organic matter and nutrients; and (3) changes in soil edaphic properties including moisture, field capacity, and texture. These patches may play a critical role as a source of soil heterogeneity in desert ecosystems, where burrows constructed in interpatches of bare soil can act, once abandoned, as "islands of fertility," promoting the establishment of plants in an otherwise hostile environment.

RevDate: 2019-03-20

Jonathan RL, Hernández-López A, Estrada-Navarrete G, et al (2019)

The non-canonical heat shock protein PvNod22 is essential for infection thread progression during rhizobial endosymbiosis in common bean.

Molecular plant-microbe interactions : MPMI [Epub ahead of print].

In the establishment of plant-rhizobial symbiosis, the plant hosts express nodulin proteins during root nodule organogenesis. A limited number of nodulins have been characterized, and these perform essential functions in root nodule development and metabolism. Most nodulins are expressed in the nodule and at lower levels in other plant tissues. Previously, we isolated Nodulin 22 (PvNod22) from a common bean (Phaseolus vulgaris L.) cDNA library derived from Rhizobium-infected roots. PvNod22 is a non-canonical, endoplasmic reticulum (ER)-localized, small heat shock protein (sHsp) that confers protection against oxidative stress when over-expressed in Escherichia coli. Virus-induced gene silencing of PvNod22 resulted in necrotic lesions in the aerial organs of P. vulgaris plants cultivated under optimal conditions, activation of the ER-unfolded protein response (UPR) and, finally, in plant death. Here, we examined the expression of PvNod22 in common bean plants during the establishment of rhizobial endosymbiosis and its relationship with two cellular processes associated with plant immunity, the UPR and autophagy. In the RNA interference lines, numerous infection threads stopped their progression before reaching the cortex cell layer of the root, and nodules contained fewer nitrogen-fixing bacteroids. Collectively, our results suggest that PvNod22 has a non-redundant function during legume-rhizobia symbiosis associated with infection thread elongation likely by sustaining protein homeostasis in the ER.

RevDate: 2019-03-20

Bayliss SLJ, Scott ZR, Coffroth MA, et al (2019)

Genetic variation in Breviolum antillogorgium, a coral reef symbiont, in response to temperature and nutrients.

Ecology and evolution, 9(5):2803-2813 pii:ECE34959.

Symbionts within the family Symbiodiniaceae are important on coral reefs because they provide significant amounts of carbon to many different reef species. The breakdown of this mutualism that occurs as a result of increasingly warmer ocean temperatures is a major threat to coral reef ecosystems globally. Recombination during sexual reproduction and high rates of somatic mutation can lead to increased genetic variation within symbiont species, which may provide the fuel for natural selection and adaptation. However, few studies have asked whether such variation in functional traits exists within these symbionts. We used several genotypes of two closely related species, Breviolum antillogorgium and B. minutum, to examine variation of traits related to symbiosis in response to increases in temperature or nitrogen availability in laboratory cultures. We found significant genetic variation within and among symbiont species in chlorophyll content, photosynthetic efficiency, and growth rate. Two genotypes showed decreases in traits in response to increased temperatures predicted by climate change, but one genotype responded positively. Similarly, some genotypes within a species responded positively to high-nitrogen environments, such as those expected within hosts or eutrophication associated with global change, while other genotypes in the same species responded negatively, suggesting context-dependency in the strength of mutualism. Such variation in traits implies that there is potential for natural selection on symbionts in response to temperature and nutrients, which could confer an adaptive advantage to the holobiont.

RevDate: 2019-03-20
CmpDate: 2019-03-20

Afzal I, Shinwari ZK, Sikandar S, et al (2019)

Plant beneficial endophytic bacteria: Mechanisms, diversity, host range and genetic determinants.

Microbiological research, 221:36-49.

Endophytic bacteria are the plant beneficial bacteria that thrive inside plants and can improve plant growth under normal and challenging conditions. They can benefit host plants directly by improving plant nutrient uptake and by modulating growth and stress related phytohormones. Indirectly, endophytic bacteria can improve plant health by targeting pests and pathogens with antibiotics, hydrolytic enzymes, nutrient limitation, and by priming plant defenses. To confer these benefits, the bacteria have to colonize the plant endosphere after colonizing the rhizosphere. The colonization is achieved using a battery of traits involving motility, attachment, plant-polymer degradation, and evasion of plant defenses. The diversity of endophytic colonizers depends on several bacteria, plant and environment specific factors. Some endophytic bacteria can have a broad host range and can be used as bioinoculants in developing a safe and sustainable agriculture system. This review elaborates the factors affecting diversity of bacterial endophytes, their host specificity and mechanisms of plant growth promotion. The review also accentuates various methods used to study endophytic communities, wild plants as a source of novel endophytic bacteria, and innovative approaches that may improve plant-endophyte association. Moreover, bacterial genes expressed in planta and challenges to study them are also discussed.

RevDate: 2019-03-20
CmpDate: 2019-03-20

Muresu R, Porceddu A, Sulas L, et al (2019)

Nodule-associated microbiome diversity in wild populations of Sulla coronaria reveals clues on the relative importance of culturable rhizobial symbionts and co-infecting endophytes.

Microbiological research, 221:10-14.

The culturable bacteria from root nodules of Sulla coronaria growing in spontaneous conditions in Sardinia were characterized. This plant's peculiarity is to represent a legume still found in both wild and cropped statuses. We tested whether culturable bacteria would differ from those commonly isolated from its field-cropped varieties, to date exclusively represented by Rhizobium sullae. 63 isolates from 60 surface-sterilized nodules were analyzed by ARDRA and 16S rDNA sequencing. The official nitrogen-fixing symbiont Rhizobium sullae was found only in 25 nodules out of 60. The remaining nodules did not yield culturable rhizobia but a number of different endophytic genera including Pseudomonas sp. (17 nodules), Microbacterium sp. (15 nodules), Pantoea agglomerans (5 nodules). The situation appears therefore a hybrid between what is commonly observed in other Mediterranean legumes occurring only in wild status (featuring non-culturable rhizobia and arrays of culturable endophytes within nodules), as opposed to cropped legumes (endowed with fully culturable rhizobia and minimal endophytic occurrence). These findings, within a species bridging the ecology between native and cropped conditions, suggest insights on the relative importance of endophytic co-occupancy vs. true N-fixing symbiont culturability within nodules. The latter trait thus appears to accompany the domestication path of plants with a main trade-off of renouncing to interactions with a diversity of endophytic co-invaders; the relationships with those being critical in the non-cropped status. In fact, endophytes are known to promote plant growth in harsh conditions, which can be particularly stressful in the Mediterranean due to drought, highly calcareous soils, and pathogens outbreaks.

RevDate: 2019-03-20
CmpDate: 2019-02-19

Wu F, Lopatkin AJ, Needs DA, et al (2019)

A unifying framework for interpreting and predicting mutualistic systems.

Nature communications, 10(1):242 pii:10.1038/s41467-018-08188-5.

Coarse-grained rules are widely used in chemistry, physics and engineering. In biology, however, such rules are less common and under-appreciated. This gap can be attributed to the difficulty in establishing general rules to encompass the immense diversity and complexity of biological systems. Furthermore, even when a rule is established, it is often challenging to map it to mechanistic details and to quantify these details. Here we report a framework that addresses these challenges for mutualistic systems. We first deduce a general rule that predicts the various outcomes of mutualistic systems, including coexistence and productivity. We further develop a standardized machine-learning-based calibration procedure to use the rule without the need to fully elucidate or characterize their mechanistic underpinnings. Our approach consistently provides explanatory and predictive power with various simulated and experimental mutualistic systems. Our strategy can pave the way for establishing and implementing other simple rules for biological systems.

RevDate: 2019-03-20
CmpDate: 2019-02-19

Cropp RA, J Norbury (2018)

Obligate Mutualism in an Extended Consumer-Resource Framework.

The Yale journal of biology and medicine, 91(4):375-389.

The development of a theory to underpin the obligate mutualist interactions that appear to be ubiquitous in nature has not proceeded at the same pace as the development of theory to support competition and predation. A constraint may be that obligate mutualism appears unable to be presented in the simple linear models that have so successfully served as heuristics for the other interactions. A number of simple nonlinear models have been used to propose explanations of obligate mutualism, but these solutions are often predicated on careful choices of functional forms. We present a theory of obligate mutualism in an explicit mass-conserving framework using simple models that are robust to choices of functional forms.

RevDate: 2019-03-20
CmpDate: 2019-03-20

Derakhshani H, Plaizier JC, De Buck J, et al (2018)

Association of bovine major histocompatibility complex (BoLA) gene polymorphism with colostrum and milk microbiota of dairy cows during the first week of lactation.

Microbiome, 6(1):203.

BACKGROUND: The interplay between host genotype and commensal microbiota at different body sites can have important implications for health and disease. In dairy cows, polymorphism of bovine major histocompatibility complex (BoLA) gene has been associated with susceptibility to several infectious diseases, most importantly mastitis. However, mechanisms underlying this association are yet poorly understood. In the present study, we sought to explore the association of BoLA gene polymorphism with the dynamics of mammary microbiota during the first week of lactation.

RESULTS: Colostrum and milk samples were collected from multiparous Holstein dairy cows at the day of calving and days 1 and 6 after calving. Microbiota profiling was performed using high-throughput sequencing of the V1-V2 regions of the bacterial 16S rRNA genes and ITS2 region of the fungal ribosomal DNA. Polymorphism of BoLA genes was determined using PCR-RFLP of exon 2 of the BoLA-DRB3. In general, transition from colostrum to milk resulted in increased species richness and diversity of both bacterial and fungal communities. The most dominant members of intramammary microbiota included Staphylococcus, Ruminococcaceae, and Clostridiales within the bacterial community and Alternaria, Aspergillus, Candida, and Cryptococcus within the fungal community. Comparing the composition of intramammary microbiota between identified BoLA-DRB3.2 variants (n = 2) revealed distinct clustering pattern on day 0, whereas this effect was not significant on the microbiota of milk samples collected on subsequent days. On day 0, proportions of several non-aureus Staphylococcus (NAS) OTUs, including those aligned to Staphylococcus equorum, Staphylococcus gallinarum, Staphylococcus sciuri, and Staphylococcus haemolyticus, were enriched within the microbiota of one of the BoLA-DRB3.2 variants, whereas lactic acid bacteria (LAB) including Lactobacillus and Enterococcus were enriched within the colostrum microbiota of the other variant.

CONCLUSION: Our results suggest a potential role for BoLA-gene polymorphism in modulating the composition of colostrum microbiota in dairy cows. Determining whether BoLA-mediated shifts in the composition of colostrum microbiota are regulated directly by immune system or indirectly by microbiota-derived colonization resistant can have important implications for future development of preventive/therapeutic strategies for controlling mastitis.

RevDate: 2019-03-20

Sommer AJ, PD Newell (2019)

Metabolic Basis for Mutualism between Gut Bacteria and Its Impact on the Drosophila melanogaster Host.

Applied and environmental microbiology, 85(2): pii:AEM.01882-18.

Interactions between species shape the formation and function of microbial communities. In the gut microbiota of animals, cross-feeding of metabolites between microbes can enhance colonization and influence host physiology. We examined a mutually beneficial interaction between two bacteria isolated from the gut microbiota of Drosophila, i.e., Acetobacter fabarum and Lactobacillus brevis After developing an in vitro coculture assay, we utilized a genetic screen to identify A. fabarum genes required for enhanced growth with L. brevis The screen, and subsequent genetic analyses, showed that the gene encoding pyruvate phosphate dikinase (ppdK) is required for A. fabarum to benefit fully from coculture. By testing strains with mutations in a range of metabolic genes, we provide evidence that A. fabarum can utilize multiple fermentation products of L. brevis Mutualism between the bacteria in vivo affects gnotobiotic Drosophila melanogaster; flies associated with A. fabarum and L. brevis showed >1,000-fold increases in bacterial cell density and significantly lower triglyceride storage than monocolonized flies. Mutation of ppdK decreased A. fabarum density in flies cocolonized with L. brevis, consistent with the model in which Acetobacter employs gluconeogenesis to assimilate Lactobacillus fermentation products as a source of carbon in vivo We propose that cross-feeding between these groups is a common feature of microbiota in DrosophilaIMPORTANCE The digestive tracts of animals are home to a community of microorganisms, the gut microbiota, which affects the growth, development, and health of the host. Interactions among microbes in this inner ecosystem can influence which species colonize the gut and can lead to changes in host physiology. We investigated a mutually beneficial interaction between two bacterial species from the gut microbiota of fruit flies. By coculturing the bacteria in vitro, we were able to identify a metabolic gene required for the bacteria to grow better together than they do separately. Our data suggest that one species consumes the waste products of the other, leading to greater productivity of the microbial community and modifying the nutrients available to the host. This study provides a starting point for investigating how these and other bacteria mutually benefit by sharing metabolites and for determining the impact of mutualism on host health.

RevDate: 2019-03-20
CmpDate: 2019-03-20

Grier A, McDavid A, Wang B, et al (2018)

Neonatal gut and respiratory microbiota: coordinated development through time and space.

Microbiome, 6(1):193.

BACKGROUND: Postnatal development of early life microbiota influences immunity, metabolism, neurodevelopment, and infant health. Microbiome development occurs at multiple body sites, with distinct community compositions and functions. Associations between microbiota at multiple sites represent an unexplored influence on the infant microbiome. Here, we examined co-occurrence patterns of gut and respiratory microbiota in pre- and full-term infants over the first year of life, a period critical to neonatal development.

RESULTS: Gut and respiratory microbiota collected as longitudinal rectal, throat, and nasal samples from 38 pre-term and 44 full-term infants were first clustered into community state types (CSTs) on the basis of their compositional profiles. Multiple methods were used to relate the occurrence of CSTs to temporal microbiota development and measures of infant maturity, including gestational age (GA) at birth, week of life (WOL), and post-menstrual age (PMA). Manifestation of CSTs followed one of three patterns with respect to infant maturity: (1) chronological, with CST occurrence frequency solely a function of post-natal age (WOL), (2) idiosyncratic to maturity at birth, with the interval of CST occurrence dependent on infant post-natal age but the frequency of occurrence dependent on GA at birth, and (3) convergent, in which CSTs appear first in infants of greater maturity at birth, with occurrence frequency in pre-terms converging after a post-natal interval proportional to pre-maturity. The composition of CSTs was highly dissimilar between different body sites, but the CST of any one body site was highly predictive of the CSTs at other body sites. There were significant associations between the abundance of individual taxa at each body site and the CSTs of the other body sites, which persisted after stringent control for the non-linear effects of infant maturity. Canonical correlations exist between the microbiota composition at each pair of body sites, with the strongest correlations between proximal locations.

CONCLUSION: These findings suggest that early microbiota is shaped by neonatal innate and adaptive developmental responses. Temporal progression of CST occurrence is influenced by infant maturity at birth and post-natal age. Significant associations of microbiota across body sites reveal distal connections and coordinated development of the infant microbial ecosystem.

RevDate: 2019-03-20
CmpDate: 2019-02-20

Song Y, Cai ZH, Lao YM, et al (2018)

Antibiofilm activity substances derived from coral symbiotic bacterial extract inhibit biofouling by the model strain Pseudomonas aeruginosa PAO1.

Microbial biotechnology, 11(6):1090-1105.

The mitigation of biofouling has received significant research attention, with particular focus on non-toxic and sustainable strategies. Here, we investigated quorum sensing inhibitor (QSI) bacteria as a means of controlling biofouling in a laboratory-scale system. Approximately, 200 strains were isolated from coral (Pocillopora damicornis) and screened for their ability to inhibit quorum sensing (QS). Approximately, 15% of the isolates exhibited QSI activity, and a typical coral symbiotic bacterium, H12-Vibrio alginolyticus, was selected in order for us to investigate quorum sensing inhibitory activity further. Confocal microscopy revealed that V. alginolyticus extract inhibited biofilm formation from Pseudomonas aeruginosa PAO1. In addition, the secondary metabolites of V. alginolyticus inhibited PAO1 virulence phenotypes by downregulating motility ability, elastase activity and rhamnolipid production. NMR and MS spectrometry suggested that the potential bioactive compound involved was rhodamine isothiocyanate. Quantitative real-time PCR indicated that the bacterial extract induced a significant downregulation of QS regulatory genes (lasB, lasI, lasR, rhlI, rhlR) and virulence-related genes (pqsA, pqsR). The possible mechanism underlying the action of rhodamine isothiocyanate analogue involves the disruption of the las and/or rhl system of PAO1. Our results highlight coral microbes as a bioresource pool for developing QS inhibitors and identifying novel antifouling agents.

RevDate: 2019-03-20
CmpDate: 2019-02-19

Guo Y, K Narisawa (2018)

Fungus-Bacterium Symbionts Promote Plant Health and Performance.

Microbes and environments, 33(3):239-241.

RevDate: 2019-03-20
CmpDate: 2019-02-19

Santos SR, MA Coffroth (2018)

Revisiting "Genetic Diversity of Symbiotic Dinoflagellates in the Genus Symbiodinium".

Protist, 169(5):784-787.

RevDate: 2019-03-20
CmpDate: 2019-02-19

Wasai S, K Minamisawa (2018)

Plant-Associated Microbes: From Rhizobia To Plant Microbiomes.

Microbes and environments, 33(1):1-3.

RevDate: 2019-03-20
CmpDate: 2019-02-19

Imachi H (2017)

Topic of Influence, Methane and Microbes.

Microbes and environments, 32(4):297-299.

RevDate: 2019-03-20
CmpDate: 2019-03-20

Anonymous (2017)

.

Nihon Rinsho Men'eki Gakkai kaishi = Japanese journal of clinical immunology, 40(4):257b.

RevDate: 2019-03-20
CmpDate: 2019-02-19

Mech AM, Harper SJ, Havill NP, et al (2019)

Ecological factors influencing the beneficial endosymbionts of the hemlock woolly adelgid (Hemiptera: Adelgidae).

Insect science, 26(1):97-107.

Bacterial endosymbionts of sap-sucking insects provide their host with a number of beneficial qualities, including the supply of nutrition, defense against parasitoids, and protection from heat stress. Damage to these bacterial associates can therefore have a negative impact on the fitness of their insect host. We evaluated observational and experimental factors regarding the nonnative hemlock woolly adelgid (Adelges tsugae Annand) (Hemiptera: Adelgidae) to help understand the roles of its three recently identified symbionts, including under heat stress conditions. The prevalence of A. tsugae's facultative symbiont (Serratia symbiotica) was examined at different spatial scales to determine how variable infection rates are for this symbiont. There was no significant difference found in infection rates between adelgids on a tree, within a plot, or within a state. However, significantly more adelgids in Georgia (95%) had S. symbiotica compared to those in New York (68%). Microsatellite genotyping of the adelgids found that this difference was most likely not the result of a second introduction of A. tsugae into eastern North America. Comparison of S. symbiotica proportions between first and fourth instars showed that symbiont absence did not affect the ability of A. tsugae to survive aestivation. Evaluations of symbiont densities within each adelgid found that when S. symbiotica was absent, the density of obligate symbionts was significantly higher. Exposure to heat stress (32.5 °C) was not consistently correlated with changes in symbiont densities over a 4-d period. Overall, we have shown that symbiont prevalence and densities vary within the broad population of A. tsugae in eastern North America, with potentially significant effects upon the ecology of this important pest.

RevDate: 2019-03-20
CmpDate: 2019-02-19

Cheng M, Chen Y, Wang L, et al (2017)

Commensal microbiota maintains alveolar macrophages with a low level of CCL24 production to generate anti-metastatic tumor activity.

Scientific reports, 7(1):7471.

Microbiota maintains host tissue homeostasis and influences tissue-resident macrophages. However, the mechanisms by which commensal bacteria in regulating the alveolar macrophages remain unclear. Here, by using an antibiotic-treated (Abt) mouse model, we found commensal bacteria depletion induced lower frequencies and numbers of alveolar macrophages. This effect was accompanied by the altered levels of genes involved in several biological pathways, including M2 macrophage polarization, as determined by gene expression analysis. Alveolar macrophages from the Abt mice had higher protein and gene levels of Arg1, CCL24, IL-13, IL-10, IL-6 and IL-1β, which could be recovered to normal levels by reconstructing commensal bacteria in the upper respiratory of Abt mice. Moreover, alveolar macrophages performed significant enhancement of M2 functions, especially CCL24 secretion, in the Abt mice challenged with B16/F10 melanoma. Adoptive transfer of normal alveolar macrophages or antibody neutralization of CCL24 significantly recovered the decrease of γδT17 cells and rescued the defect anti-tumor response of Abt mice, indicating the elevated amount of alveolar macrophage-derived CCL24 inhibited γδT cell mediated anti-tumor response. In conclusion, we demonstrated the ability of commensal bacteria to maintain alveolar macrophages with a low level of CCL24 production, which was necessary for the normal anti-tumor response in the lung.

RevDate: 2019-03-20
CmpDate: 2017-06-12

Cooper WR, Garczynski SF, Horton DR, et al (2017)

Bacterial Endosymbionts of the Psyllid Cacopsylla pyricola (Hemiptera: Psyllidae) in the Pacific Northwestern United States.

Environmental entomology, 46(2):393-402.

Insects often have facultative associations with bacterial endosymbionts, which can alter the insects' susceptibility to parasitism, pathogens, plant defenses, and certain classes of insecticides. We collected pear psylla, Cacopsylla pyricola (Förster) (Hemiptera: Psyllidae), from pear orchards in Washington and Oregon, and surveyed them for the presence of bacterial endosymbionts. Adult psyllids were collected on multiple dates to allow us to assay specimens of both the summer ("summerform") and the overwintering ("winterform") morphotypes. Two endosymbionts, Arsenophonus and Phytoplasma pyri, were detected in psyllids of both morphotypes in both states. A separate survey revealed similar associations present in psyllids collected in 1987. Arsenophonus was present in 80-100% of psyllids in all growing regions. A slightly lower proportion of summerform than winterform psyllids harbored the bacterium. Arsenophonus was present in the bacteriomes and developing oocytes of most psyllids, indicating that this endosymbiont is transovarially transmitted. This bacterium was also observed in the salivary glands and midguts of some psyllids. Phytoplasma pyri was present in a greater proportion of pear psylla from orchards near Yakima, WA, than from other regions, and was present in a higher proportion of winterforms than summerforms. We did not detect Wolbachia, Profftella, or Liberibacter europaeus, which are associated with other psyllid pests, including other species of Cacopsylla. Our study is the first to survey North American populations of C. pyricola for endosymbionts, and provides a foundation for further research on how bacterial associations may influence the ecology and management of this pest.

RevDate: 2019-03-20
CmpDate: 2019-02-19

Khoshmanesh A, Christensen D, Perez-Guaita D, et al (2017)

Screening of Wolbachia Endosymbiont Infection in Aedes aegypti Mosquitoes Using Attenuated Total Reflection Mid-Infrared Spectroscopy.

Analytical chemistry, 89(10):5285-5293.

Dengue fever is the most common mosquito transmitted viral infection afflicting humans, estimated to generate around 390 million infections each year in over 100 countries. The introduction of the endosymbiotic bacterium Wolbachia into Aedes aegypti mosquitoes has the potential to greatly reduce the public health burden of the disease. This approach requires extensive polymerase chain reaction (PCR) testing of the Wolbachia-infection status of mosquitoes in areas where Wolbachia-A. aegypti are released. Here, we report the first example of small organism mid-infrared spectroscopy where we have applied attenuated total reflection Fourier transform infrared (ATR-FT-IR) spectroscopy and multivariate modeling methods to determine sex, age, and the presence of Wolbachia (wMel strain) in laboratory mosquitoes and sex and age in field mosquitoes. The prediction errors using partial least squares discriminant analysis (PLS-DA) discrimination models for laboratory studies on independent test sets ranged from 0 to 3% for age and sex grading and 3% to 5% for Wolbachia infection diagnosis using dry mosquito abdomens while field study results using an artificial neural network yielded a 10% error. The application of FT-IR analysis is inexpensive, easy to use, and portable and shows significant potential to replace the reliance on more expensive and laborious PCR assays.

RevDate: 2019-03-01
CmpDate: 2019-03-01

Amid C, Olstedt M, Gunnarsson JS, et al (2018)

Additive effects of the herbicide glyphosate and elevated temperature on the branched coral Acropora formosa in Nha Trang, Vietnam.

Environmental science and pollution research international, 25(14):13360-13372.

The combined effects of the herbicide glyphosate and elevated temperature were studied on the tropical staghorn coral Acropora formosa, in Nha Trang bay, Vietnam. The corals were collected from two different reefs, one close to a polluted fish farm and one in a marine-protected area (MPA). In the laboratory, branches of the corals were exposed to the herbicide glyphosate at ambient (28 °C) and at 3 °C elevated water temperatures (31 °C). Effects of herbicide and elevated temperature were studied on coral bleaching using photography and digital image analysis (new colorimetric method developed here based on grayscale), chlorophyll a analysis, and symbiotic dinoflagellate (Symbiodinium, referred to as zooxanthellae) counts. All corals from the MPA started to bleach in the laboratory before they were exposed to the treatments, indicating that they were very sensitive, as opposed to the corals collected from the more polluted site, which were more tolerant and showed no bleaching response to temperature increase or herbicide alone. However, the combined exposure to the stressors resulted in significant loss of color, proportional to loss in chlorophyll a and zooxanthellae. The difference in sensitivity of the corals collected from the polluted site versus the MPA site could be explained by different symbiont types: the resilient type C3u and the stress-sensitive types C21 and C23, respectively. The additive effect of elevated temperatures and herbicides adds further weight to the notion that the bleaching of coral reefs is accelerated in the presence of multiple stressors. These results suggest that the corals in Nha Trang bay have adapted to the ongoing pollution to become more tolerant to anthropogenic stressors, and that multiple stressors hamper this resilience. The loss of color and decrease of chlorophyll a suggest that bleaching is related to concentration of chloro-pigments. The colorimetric method could be further fine-tuned and used as a precise, non-intrusive tool for monitoring coral bleaching in situ.

RevDate: 2019-03-20
CmpDate: 2017-08-23

Ploetz RC, Konkol JL, Narvaez T, et al (2017)

Presence and Prevalence of Raffaelea lauricola, Cause of Laurel Wilt, in Different Species of Ambrosia Beetle in Florida, USA.

Journal of economic entomology, 110(2):347-354.

We summarize the information available on ambrosia beetle species that have been associated in Florida with Raffaelea lauricola T.C. Harr., Fraedrich & Aghayeva, the primary symbiont of Xyleborus glabratus Eichhoff and cause of laurel wilt. In total, 14 species in Ambrosiodmus, Euwallacea, Premnobius, Xyleborus, Xyleborinus, and Xylosandrus were either reared from laurel wilt-affected host trees or trapped in laurel wilt-affected stands of the same, and assayed for R. lauricola. In six collections from native species in the southeastern United States [Persea borbonia (L.), Persea palustris (Raf.) Sarg., and Persea humilis Nash] and four from avocado (Persea americana Mill.), extracted mycangia or heads (taxa with mandibular mycangia) or intact bodies (taxa with mycangia in other locations) were surface-disinfested before assays on a semi-selective medium for the isolation of Raffaelea (CSMA+). Raffaelea lauricola was identified based on its characteristic phenotype on CSMA+, and the identity of a random subset of isolates was confirmed with taxon-specific microsatellite markers. The pathogen was recovered from 34% (246 of 726) of the individuals that were associated with the native Persea spp., but only 6% (58 of 931) of those that were associated with avocado. Over all studies, R. lauricola was recovered from 10 of the ambrosia beetle species, but it was most prevalent in Xyleborus congeners. This is the first record of R. lauricola in Ambrosiodmus lecontei Hopkins, Xyleborinus andrewesi (Blandford), and Xyleborus bispinatus Eichhoff. The potential effects of R. lauricola's promiscuity are discussed.

RevDate: 2019-03-20
CmpDate: 2019-02-19

Bogacheva AS, Shaikevich EV, Rakova VM, et al (2017)

[(THE FAUNA OF BLOODSUCKING MOSQUITOES IN THE NIZHNY NOVGOROD REGION, THEIR INFECTION WITH DIROFILARIA AND ENDOSYMBIOTIC BACTERIA)].

Meditsinskaia parazitologiia i parazitarnye bolezni, 1(1):43-47.

The fauna of bloodsucking mosquitoes in the Nizhny Novgorod Region is represented by 11 species from 5 genera of the family Culicidae. During 2014-2015, the predominant species were Ochlerotatus cantans and Aedes cinereus mosqui- toes in both a population aggregate and woodland. The infected mosquitoes accounted for 1.3% of their total number and were registered only in the village of Fokino. The investigators identified two human pathogenic nematode species: Diro- filaria immits and Dirofilaria repens (0.9% and 0.4% respectively). The effective carriers of Dirofilaria in the examined area can be Ae.cinereus and Och.cantans as only these species were found to have an invasive stage of the parasite. The symbiotic bacterium Wolbachia was detected in the mosquitoes that were not infected with dirofilariasis. This is the first study in Russia to investigate the effects of Wolbachia on the susceptibility of dirofilariasis vectors to infection.

RevDate: 2019-03-19

Prasad S, Shah A, Bhalsing KS, et al (2019)

Abnormal hippocampal subfields are associated with cognitive impairment in Essential Tremor.

Journal of neural transmission (Vienna, Austria : 1996) pii:10.1007/s00702-019-01992-3 [Epub ahead of print].

Multi-domain cognitive impairment (CI) has been frequently described in patients with essential tremor (ET). However, the exact neuroanatomical basis for this impairment is uncertain. This study aims to ascertain the role of the hippocampal formation in cognitive impairment in ET. Forty patients with ET and 40 age, gender and education matched healthy controls (HC) were enrolled. Cognition was assessed using a structured neuropsychological battery and patients were categorized as ET with CI (ETCI) and ET without CI (ETNCI). Automatic segmentation of hippocampal subfields was performed using FreeSurfer 6.0. The obtained volumes were correlated with scores of neuropsychological tests. Significant atrophy of the left subiculum, CA4, granule-cell layer of dentate gyrus, right molecular layer, and hypertrophy of bilateral parasubiculum, right hippocampus-amygdala-transition-area, bilateral hippocampal tail (HT) and widening of right hippocampal fissure was observed in ET. Trends toward atrophy of right subiculum, and widening of left HF was also observed. Comparison of HC and ETCI revealed atrophy of right subiculum, hypertrophy of bilateral parasubiculum, HT, and widening of left HF. ETCI showed a trend toward widening of right HF. ETNCI had isolated left parasubicular hypertrophy and in comparison, to ETNCI the ETCI subgroup had atrophy of bilateral fimbria. Significant correlations were observed between the volumes of HT, HF, fimbria and scores of tests for executive function, working and verbal memory. Patients with ET have significant volumetric abnormalities of several hippocampal subfields and these abnormalities may be important contributors for some forms of cognitive impairment observed in ET.

RevDate: 2019-03-19

Polzin J, Arevalo P, Nussbaumer T, et al (2019)

Polyclonal symbiont populations in hydrothermal vent tubeworms and the environment.

Proceedings. Biological sciences, 286(1896):20181281.

Horizontally transmitted symbioses usually house multiple and variable symbiont genotypes that are acquired from a much more diverse environmental pool via partner choice mechanisms. However, in the deep-sea hydrothermal vent tubeworm Riftia pachyptila (Vestimentifera, Siboglinidae), it has been suggested that the Candidatus Endoriftia persephone symbiont is monoclonal. Here, we show with high-coverage metagenomics that adult R. pachyptila house a polyclonal symbiont population consisting of one dominant and several low-frequency variants. This dominance of one genotype is confirmed by multilocus gene sequencing of amplified housekeeping genes in a broad range of host individuals where three out of four loci (atpA, uvrD and recA) revealed no genomic differences, while one locus (gyrB) was more diverse in adults than in juveniles. We also analysed a metagenome of free-living Endoriftia and found that the free-living population showed greater sequence variability than the host-associated population. Most juveniles and adults shared a specific dominant genotype, while other genotypes can dominate in few individuals. We suggest that although generally permissive, partner choice is selective enough to restrict uptake of some genotypes present in the environment.

RevDate: 2019-03-19

Gano-Cohen KA, Wendlandt CE, Stokes PJ, et al (2019)

Interspecific conflict and the evolution of ineffective rhizobia.

Microbial symbionts exhibit broad genotypic variation in their fitness effects on hosts, leaving hosts vulnerable to costly partnerships. Interspecific conflict and partner-maladaptation are frameworks to explain this variation, with different implications for mutualism stability. We investigated the mutualist service of nitrogen fixation in a metapopulation of root-nodule forming Bradyrhizobium symbionts in Acmispon hosts. We uncovered Bradyrhizobium genotypes that provide negligible mutualist services to hosts and had superior in planta fitness during clonal infections, consistent with cheater strains that destabilise mutualisms. Interspecific conflict was also confirmed at the metapopulation level - by a significant negative association between the fitness benefits provided by Bradyrhizobium genotypes and their local genotype frequencies - indicating that selection favours cheating rhizobia. Legumes have mechanisms to defend against rhizobia that fail to fix sufficient nitrogen, but these data support predictions that rhizobia can subvert plant defenses and evolve to exploit hosts.

RevDate: 2019-03-19

Shi YM, Brachmann AO, Westphalen MA, et al (2019)

Dual phenazine gene clusters enable diversification during biosynthesis.

Nature chemical biology pii:10.1038/s41589-019-0246-1 [Epub ahead of print].

Biosynthetic gene clusters (BGCs) bridging genotype and phenotype continuously evolve through gene mutations and recombinations to generate chemical diversity. Phenazine BGCs are widespread in bacteria, and the biosynthetic mechanisms of the formation of the phenazine structural core have been illuminated in the last decade. However, little is known about the complex phenazine core-modification machinery. Here, we report the diversity-oriented modifications of the phenazine core through two distinct BGCs in the entomopathogenic bacterium Xenorhabdus szentirmaii, which lives in symbiosis with nematodes. A previously unidentified aldehyde intermediate, which can be modified by multiple enzymatic and non-enzymatic reactions, is a common intermediate bridging the pathways encoded by these BGCs. Evaluation of the antibiotic activity of the resulting phenazine derivatives suggests a highly effective strategy to convert Gram-positive specific phenazines into broad-spectrum antibiotics, which might help the bacteria-nematode complex to maintain its special environmental niche.

RevDate: 2019-03-19
CmpDate: 2019-03-19

Maciel JF, Matter LB, Tasca C, et al (2019)

Characterization of intestinal Escherichia coli isolated from calves with diarrhea due to rotavirus and coronavirus.

Journal of medical microbiology, 68(3):417-423.

PURPOSE: To address more information about changes in commensal Escherichia coli during virus intestinal infection, we characterized 30 faecal E. coli isolates from calves (21 to 60 days old) with diarrhea due to rotavirus and coronavirus, which received, before diagnosis, tetracycline, gentamicin and enrofloxacin drugs.

METHODOLOGY: Clermont's phylogenetic classification; presence of genes for curli, cellulose, fimbriae (F4, F5, F6, F18, F41); and antimicrobial susceptibility were used to characterize the isolates. Disk diffusion technique and PCR were used as methodologies.

RESULTS: E. coli isolates from calves with diarrhea were phylogenetically classified as B1 (70%, 21/30), B2 (3.33%, 1/30), C (3.33%, 1/30), D (3.33%, 1/30), E (13.33%, 4/30) and unknown (6.7 %; 2/30), whereas E. coli isolates from the control group were classified only as B1 (83.3%, 25/30), E (10 %; 3/30) and unknown (6,7 %; 2/30). E. coli isolates from calves with diarrhea showed a much higher resistance profile with 16 (53.3%) multiresistant isolates. Only isolates (30%-9/30) from diarrheic calves were also positive for fimbriae, specifically 16.7% (5/30) for F5 and 13.3% (4/30) for F18.

CONCLUSION: To sum up, E. coli isolates from calves with diarrhea showed differences in relation to the control group, confirming changes in commensal E. coli during virus intestinal infection. It can be emphasized that some care should be taken to manage diarrheic calves: the pathological agent must be diagnosed prior to treatment; antibacterial treatment should be with antimicrobials with a different mechanism of action; and finally, treated animals should be maintained separately from others because they can carry micro-organisms with a resistant profile.

RevDate: 2019-03-19
CmpDate: 2019-03-19

Mirandola Dias Vieira DH, Abdallah VD, José da Silva R, et al (2019)

Skin nodules associated with parasitism with Henneguya sp. (Cnidaria: Myxosporea) in the neotropical fish Cyphocharax modestus.

Microbial pathogenesis, 128:294-300.

A new myxozoan species, Henneguya sp., is described based on material from skin of Cyphocharax modestus. Mature myxospores are were elongate and ellipsoidal, measuring 21.4 ± 1.2 (19.4-23.2) μm in total length, 5.1 ± 0.3 (4.5-5.8) μm in width, 11.9 ± 0.5 (10.9-12.7) μm in body length and 9.6 ± 0.7 (8.4-10.5) μm in length of the caudal process. The polar capsules were elongated and had unequal sizes, with length of 5.1 ± 0.4 (4.5-6.0) μm and 5.6 ± 0.4 (4.9-6.3) μm for smaller and larger respectively and width of 1.8 ± 0.2 (1.4-2.0) μm. The larger polar capsule had 8 turns in polar filament while the smaller polar capsule had 5 turns in polar filament. The macroscopic analysis revealed the presence of large nodules, which were located before and after the dorsal fin of the hosts. The histopathological analysis showed the development of nodules filled with plasmodia, surrounded by loose connective tissue, developed in the dermis of the skin. Many cysts containing countless spores, as well as free spores, were located in the dermis and hypodermis of the hosts, causing the disorganization of the connective tissue that is responsible for the support. This is the first record of a Henneguya species in C. modestus.

RevDate: 2019-03-19
CmpDate: 2019-03-19

Pandey P, Wang M, Baldwin IT, et al (2018)

Complex regulation of microRNAs in roots of competitively-grown isogenic Nicotiana attenuata plants with different capacities to interact with arbuscular mycorrhizal fungi.

BMC genomics, 19(1):937 pii:10.1186/s12864-018-5338-x.

BACKGROUND: Nicotiana attenuata is an ecological model plant whose 2.57 Gb genome has recently been sequenced and assembled and for which miRNAs and their genomic locations have been identified. To understand how this plant's miRNAs are reconfigured during plant-arbuscular mycorrhizal fungal (AMF) interactions and whether hostplant calcium- and calmodulin dependent protein kinase (CCaMK) expression which regulates the AMF interaction also modulates miRNAs levels and regulation, we performed a large-scale miRNA analysis of this plant-AMF interaction.

RESULTS: Next generation sequencing of miRNAs in roots of empty vector (EV) N. attenuata plants and an isogenic line silenced in CCaMK expression (irCCaMK) impaired in AMF-interactions grown under competitive conditions with and without AMF inoculum revealed a total of 149 unique miRNAs: 67 conserved and 82 novel ones. The majority of the miRNAs had a length of 21 nucleotides. MiRNA abundances were highly variable ranging from 400 to more than 25,000 reads per million. The miRNA profile of irCCaMK plants impaired in AMF colonization was distinct from fully AMF-functional EV plants grown in the same pot. Six conserved miRNAs were present in all conditions and accumulated differentially depending on treatment and genotype; five (miR6153, miR403a-3p, miR7122a, miR167-5p and miR482d, but not miR399a-3p) showed the highest accumulation in AMF inoculated EV plants compared to inoculated irCCaMK plants. Furthermore, the accumulation patterns of sequence variants of selected conserved miRNAs showed a very distinct pattern related to AMF colonization - one variant of miR473-5p specifically accumulated in AMF-inoculated plants. Also abundances of miR403a-3p, miR171a-3p and one of the sequence variants of miR172a-3p increased in AMF-inoculated EV compared to inoculated irCCaMK plants and to non-inoculated EV plants, while miR399a-3p was most strongly enriched in AMF inoculated irCCaMK plants grown in competition with EV. The analysis of putative targets of selected miRNAs revealed an involvement in P starvation (miR399), phytohormone signaling (Nat-R-PN59, miR172, miR393) and defense (e.g. miR482, miR8667, Nat-R-PN-47).

CONCLUSIONS: Our study demonstrates (1) a large-scale reprograming of miRNAs induced by AMF colonization and (2) that the impaired AMF signaling due to CCaMK silencing and the resulting reduced competitive ability of irCCaMK plants play a role in modulating signal-dependent miRNA accumulation.

RevDate: 2019-03-19
CmpDate: 2019-03-19

Heo YM, Kim K, Ryu SM, et al (2018)

Diversity and Ecology of Marine Algicolous Arthrinium Species as a Source of Bioactive Natural Products.

Marine drugs, 16(12): pii:md16120508.

In our previous study, all Arthrinium isolates from Sargassum sp. showed high bioactivities, but studies on marine Arthrinium spp. are insufficient. In this study, a phylogenetic analysis of 28 Arthrinium isolates from seaweeds and egg masses of Arctoscopus japonicus was conducted using internal transcribed spacers, nuclear large subunit rDNA, β-tubulin, and translation elongation factor region sequences, and their bioactivities were investigated. They were analyzed as 15 species, and 11 of them were found to be new species. Most of the extracts exhibited radical-scavenging activity, and some showed antifungal activities, tyrosinase inhibition, and quorum sensing inhibition. It was implied that marine algicolous Arthrinium spp. support the regulation of reactive oxygen species in symbiotic algae and protect against pathogens and bacterial biofilm formation. The antioxidant from Arthrinium sp. 10 KUC21332 was separated by bioassay-guided isolation and identified to be gentisyl alcohol, and the antioxidant of Arthrinium saccharicola KUC21221 was identical. These results demonstrate that many unexploited Arthrinium species still exist in marine environments and that they are a great source of bioactive compounds.

RevDate: 2019-03-19
CmpDate: 2019-03-19

Kobayashi G, JF Araya (2018)

Southernmost records of Escarpia spicata and Lamellibrachia barhami (Annelida: Siboglinidae) confirmed with DNA obtained from dried tubes collected from undiscovered reducing environments in northern Chile.

PloS one, 13(10):e0204959.

Deep-sea fishing bycatch enables collection of samples of rare species that are not easily accessible, for research purposes. However, these specimens are often degraded, losing diagnostic morphological characteristics. Several tubes of vestimentiferans, conspicuous annelids endemic to chemosynthetic environments, were obtained from a single batch of deep-sea fishing bycatch at depths of around 1,500 m off Huasco, northern Chile, as part of an ongoing study examining bycatch species. DNA sequences of the mitochondrial cytochrome c oxidase subunit I (COI) gene and an intron region within the hemoglobin subunit B2 (hbB2i) were successfully determined using vestimentiferans' dried-up tubes and their degraded inner tissue. Molecular phylogenetic analyses based on DNA sequence identified the samples as Escarpia spicata Jones, 1985, and Lamellibrachia barhami Webb, 1969. These are the southernmost records, vastly extending the geographical ranges of both species from Santa Catalina Island, California to northern Chile for E. spicata (over 8,000 km), and from Vancouver Island Margin to northern Chile for L. barhami (over 10,000 km). We also determined a 16S rRNA sequence of symbiotic bacteria of L. barhami. The sequence of the bacteria is the same as that of E. laminata, Lamellibrachia sp. 1, and Lamellibrachia sp.2 known from the Gulf of Mexico. The present study provides sound evidence forthe presence of reducing environments along the continental margin of northern Chile.

RevDate: 2019-03-19

Mockler BK, Kwong WK, Moran NA, et al (2018)

Microbiome Structure Influences Infection by the Parasite Crithidia bombi in Bumble Bees.

Applied and environmental microbiology, 84(7):.

Recent declines in bumble bee populations are of great concern and have prompted critical evaluations of the role of pathogen introductions and host resistance in bee health. One factor that may influence host resilience when facing infection is the gut microbiota. Previous experiments with Bombus terrestris, a European bumble bee, showed that the gut microbiota can protect against Crithidia bombi, a widespread trypanosomatid parasite of bumble bees. However, the particular characteristics of the microbiome responsible for this protective effect have thus far eluded identification. Using wild and commercially sourced Bombus impatiens, an important North American pollinator, we conducted cross-wise microbiota transplants to naive hosts of both backgrounds and challenged them with a Crithidia parasite. As with B. terrestris, we find that microbiota-dependent protection against Crithidia operates in B. impatiens Lower Crithidia infection loads were experimentally associated with high microbiome diversity, large gut bacterial populations, and the presence of Apibacter, Lactobacillus Firm-5, and Gilliamella spp. in the gut community. These results indicate that even subtle differences between gut community structures can have a significant impact on a microbiome's ability to defend against parasite infections.IMPORTANCE Many wild bumble bee populations are under threat due to human activity, including through the introduction of pathogens via commercially raised bees. Recently, it was found that the bumble bee gut microbiota can help defend against a common parasite, Crithidia bombi, but the particular factors contributing to this protection are unknown. Using both wild and commercially raised bees, we conducted microbiota transplants to show that microbiome diversity, total gut bacterial load, and the presence of certain core members of the microbiota may all impact bee susceptibility to Crithidia infection. Bee origin (genetic background) was also a factor. Finally, by examining this phenomenon in a previously uninvestigated bee species, our study demonstrates that microbiome-mediated resistance to Crithidia is conserved across multiple bumble bee species. These findings highlight how intricate interactions between hosts, microbiomes, and parasites can have wide-ranging consequences for the health of ecologically important species.

RevDate: 2019-03-18

Azmat R, S Moin (2019)

The remediation of drought stress under VAM inoculation through proline chemical transformation action.

Journal of photochemistry and photobiology. B, Biology, 193:155-161 pii:S1011-1344(18)31306-X [Epub ahead of print].

This article discussed the enhanced drought tolerance under arbuscular mycorrhizal (AM) inoculation and normal growth of plants which linked with the activity of photoreceptors. The photoreceptor action in dual symbiosis under drought stress showed not only the high photosynthetic activity but also provide information about the broad range of physiological responses. The pot experiment conducted in a natural environment where drought condition was observed twice a week via regular irrigation with water up to twelve months. Plants analysis showed the high contents of water, hydrogen peroxide, carotenoids, proline, antioxidant enzymes like super dismutase (SOD) and catalase(CAT) in both leaves and roots with a large surface area of leaves over control. The elevated concentration of hydrogen peroxide (0.04 ± 0.0 μmol/g) coupled with singlet oxygen species was the main modified molecular mechanism which was operative in drought condition. The accretion of proline under drought stress in dual symbiosis (32.3 ± 0.3 μg/mL) was related to the highest branching pattern of young leaves and the chemical transformation of reactive oxygen species (ROS) including H2O2 and 3O2 into useful molecules like water and triplet molecular oxygen. The higher contents of carotenoids (5.0 ± 1.2 mg/g) in drought over control (4.8 ± 1.6 mg/g) and AM plant (4.9 ± 1.2 mg/g) was found to be supportive in the conversion of singlet oxygen into triplet one.

RevDate: 2019-03-18

Fernández I, Cosme M, Stringlis IA, et al (2019)

Molecular dialogue between arbuscular mycorrhizal fungi and the non-host plant Arabidopsis thaliana switches from initial detection to antagonism.

The New phytologist [Epub ahead of print].

Approximately 29% of all vascular plant species are unable to establish an arbuscular mycorrhizal (AM) symbiosis. Despite this, AM fungi (Rhizophagus spp.) are enriched in the root microbiome of the non-host Arabidopsis thaliana and Arabidopsis roots become colonized when AM networks nurtured by host plants are available. Here, we investigated the non-host-AM fungus interaction by analyzing transcriptional changes in Rhizophagus, Arabidopsis, and the host plant Medicago truncatula while growing in the same mycorrhizal network. In early interaction stages, Rhizophagus activated the Arabidopsis strigolactone biosynthesis genes CCD7 and CCD8, suggesting that detection of AM fungi is not completely impaired. However, in colonized Arabidopsis roots, fungal nutrient transporter genes GintPT, GintAMT2, GintMST2 and GintMST4, essential for AM symbiosis, were not activated. RNA-seq transcriptome analysis pointed to activation of costly defenses in colonized Arabidopsis roots. Moreover, Rhizophagus colonization caused a 50% reduction in shoot biomass, but also led to enhanced systemic immunity against Botrytis cinerea. This suggests that early signaling between AM fungi and Arabidopsis is not completely impaired and that incompatibility appears at later interaction stages. Moreover, Rhizophagus-mediated defenses coincide with reduced Arabidopsis growth, but also with systemic disease resistance, highlighting the multifunctional role of AM fungi in host and non-host interactions. This article is protected by copyright. All rights reserved.

RevDate: 2019-03-18

Hapeshi A, Benarroch JM, Clarke DJ, et al (2019)

Iso-propyl stilbene: a life cycle signal?.

Microbiology (Reading, England) [Epub ahead of print].

Members of the Gram-negative bacterial genus Photorhabdus are all highly insect pathogenic and exist in an obligate symbiosis with the entomopathogenic nematode worm Heterorhabditis. All members of the genus produce the small-molecule 3,5-dihydroxy-4-isopropyl-trans-stilbene (IPS) as part of their secondary metabolism. IPS is a multi-potent compound that has antimicrobial, antifungal, immunomodulatory and anti-cancer activities and also plays an important role in symbiosis with the nematode. In this study we have examined the response of Photorhabdus itself to exogenous ectopic addition of IPS at physiologically relevant concentrations. We observed that the bacteria had a measureable phenotypic response, which included a decrease in bioluminescence and pigment production. This was reflected in changes in its transcriptomic response, in which we reveal a reduction in transcript levels of genes relating to many fundamental cellular processes, such as translation and oxidative phosphorylation. Our observations suggest that IPS plays an important role in the biology of Photorhabdus bacteria, fulfilling roles in quorum sensing, antibiotic-competition advantage and maintenance of the symbiotic developmental cycle.

RevDate: 2019-03-18

Tribble GD, Angelov N, Weltman R, et al (2019)

Frequency of Tongue Cleaning Impacts the Human Tongue Microbiome Composition and Enterosalivary Circulation of Nitrate.

Frontiers in cellular and infection microbiology, 9:39.

The oral microbiome has the potential to provide an important symbiotic function in human blood pressure physiology by contributing to the generation of nitric oxide (NO), an essential cardiovascular signaling molecule. NO is produced by the human body via conversion of arginine to NO by endogenous nitric oxide synthase (eNOS) but eNOS activity varies by subject. Oral microbial communities are proposed to supplement host NO production by reducing dietary nitrate to nitrite via bacterial nitrate reductases. Unreduced dietary nitrate is delivered to the oral cavity in saliva, a physiological process termed the enterosalivary circulation of nitrate. Previous studies demonstrated that disruption of enterosalivary circulation via use of oral antiseptics resulted in increases in systolic blood pressure. These previous studies did not include detailed information on the oral health of enrolled subjects. Using 16S rRNA gene sequencing and analysis, we determined whether introduction of chlorhexidine antiseptic mouthwash for 1 week was associated with changes in tongue bacterial communities and resting systolic blood pressure in healthy normotensive individuals with documented oral hygiene behaviors and free of oral disease. Tongue cleaning frequency was a predictor of chlorhexidine-induced changes in systolic blood pressure and tongue microbiome composition. Twice-daily chlorhexidine usage was associated with a significant increase in systolic blood pressure after 1 week of use and recovery from use resulted in an enrichment in nitrate-reducing bacteria on the tongue. Individuals with relatively high levels of bacterial nitrite reductases had lower resting systolic blood pressure. These results further support the concept of a symbiotic oral microbiome contributing to human health via the enterosalivary nitrate-nitrite-NO pathway. These data suggest that management of the tongue microbiome by regular cleaning together with adequate dietary intake of nitrate provide an opportunity for the improvement of resting systolic blood pressure.

RevDate: 2019-03-18

Bamba M, Aoki S, Kajita T, et al (2019)

Exploring Genetic Diversity and Signatures of Horizontal Gene Transfer in Nodule Bacteria Associated with Lotus japonicus in Natural Environments.

Molecular plant-microbe interactions : MPMI [Epub ahead of print].

To investigate the genetic diversity and understand the process of horizontal gene transfer (HGT) in nodule bacteria associated with Lotus japonicus, we analyzed sequences of three housekeeping and five symbiotic genes using samples from a geographically wide range in Japan. A phylogenetic analysis of the housekeeping genes indicated that L. japonicus in natural environments was associated with diverse lineages of Mesorhizobium species, whereas the sequences of symbiotic genes were highly similar between strains, resulting in remarkably low nucleotide diversity at both synonymous and non-synonymous sites. Guanine-cytosine content values were lower in symbiotic genes, and relative frequencies of recombination between symbiotic genes were also lower than those between housekeeping genes. An analysis of molecular variance showed significant genetic differentiation among populations in both symbiotic and housekeeping genes. These results confirm that the Mesorhizobium genes required for symbiosis with L. japonicus behave as a genomic island (i. e. a symbiosis island) and suggest that this island has spread into diverse genomic backgrounds of Mesorhizobium via HGT events in natural environments. Furthermore, our data compilation revealed that the genetic diversity of symbiotic genes in L. japonicus-associated symbionts was among the lowest compared with reports of other species, which may be related to the recent population expansion proposed in Japanese populations of L. japonicus.

RevDate: 2019-03-18

Shitole AA, Giram PS, Raut PW, et al (2019)

Clopidogrel eluting electrospun polyurethane/polyethylene glycol thromboresistant, hemocompatible nanofibrous scaffolds.

Journal of biomaterials applications [Epub ahead of print].

Biomaterials used as blood-contacting material must be hemocompatible and exhibit lower thrombotic potential while maintaining hemostasis and angiogenesis. With the aim of developing thromboresistant, hemocompatible nanofibrous scaffolds, polyurethane/polyethylene glycol scaffolds incorporated with 1, 5, and 10 wt% Clopidogrel were fabricated and evaluated for their physiochemical properties, biocompatibility, hemocompatibility, and antithrombotic potential. The results of physicochemical characterization revealed the fabrication of nanometer-sized scaffolds with smooth surfaces. The incorporation of both polyethylene glycol and Clopidogrel to polyurethane enhanced the hydrophilicity and water uptake potential of polyurethane/polyethylene glycol/Clopidogrel scaffolds. The dynamic mechanical analysis revealed the enhancement in mechanical strength of the polyurethane/polyethylene glycol scaffolds on incorporation of Clopidogrel. The polyurethane/polyethylene glycol/Clopidogrel scaffolds showed a tri-phasic drug release pattern. The results of hemocompatibility assessment demonstrated the excellent blood compatibility of the polyurethane/polyethylene glycol/Clopidogrel scaffolds, with the developed scaffolds exhibiting lower hemolysis, increased albumin and plasma protein adsorption while reduction in fibrinogen adsorption. Further, the platelet adhesion was highly suppressed and significant increase in coagulation period was observed for Clopidogrel incorporated scaffolds. The results of cell adhesion and cell viability substantiate the biocompatibility of the developed nanofibrous scaffolds with the HUVEC cell viability on polyurethane/polyethylene glycol, polyurethane/polyethylene glycol/Clopidogrel-1, 5, and 10% at day 7 found to be 12.35, 13.36, 14.85, and 4.18% higher as compared to polyurethane scaffolds, and the NIH/3T3 cell viability found to be 35.27, 70.82, 36.60, and 7.95% higher as compared to polyurethane scaffolds, respectively. Altogether the results of the study advocate the incorporation of Clopidogrel to the polyurethane/polyethylene glycol blend in order to fabricate scaffolds with appropriate antithrombotic property, hemocompatibility, and cell proliferation capacity and thus, might be successfully used as antithrombotic material for biomedical application.

RevDate: 2019-03-18
CmpDate: 2019-03-18

Townsend GE, Han W, Schwalm ND, et al (2019)

Dietary sugar silences a colonization factor in a mammalian gut symbiont.

Proceedings of the National Academy of Sciences of the United States of America, 116(1):233-238.

The composition of the gut microbiota is largely determined by environmental factors including the host diet. Dietary components are believed to influence the composition of the gut microbiota by serving as nutrients to a subset of microbes, thereby favoring their expansion. However, we now report that dietary fructose and glucose, which are prevalent in the Western diet, specifically silence a protein that is necessary for gut colonization, but not for utilization of these sugars, by the human gut commensal Bacteroides thetaiotaomicron Silencing by fructose and glucose requires the 5' leader region of the mRNA specifying the protein, designated Roc for regulator of colonization. Incorporation of the roc leader mRNA in front of a heterologous gene was sufficient for fructose and glucose to turn off expression of the corresponding protein. An engineered strain refractory to Roc silencing by these sugars outcompeted wild-type B. thetaiotaomicron in mice fed a diet rich in glucose and sucrose (a disaccharide composed of glucose and fructose), but not in mice fed a complex polysaccharide-rich diet. Our findings underscore a role for dietary sugars that escape absorption by the host intestine and reach the microbiota: regulation of gut colonization by beneficial microbes independently of supplying nutrients to the microbiota.

RevDate: 2019-03-18
CmpDate: 2019-03-18

Hayashi M, Nomura M, D Kageyama (2018)

Rapid comeback of males: evolution of male-killer suppression in a green lacewing population.

Proceedings. Biological sciences, 285(1877):.

Evolutionary theory predicts that the spread of cytoplasmic sex ratio distorters leads to the evolution of host nuclear suppressors, although there are extremely few empirical observations of this phenomenon. Here, we demonstrate that a nuclear suppressor of a cytoplasmic male killer has spread rapidly in a population of the green lacewing Mallada desjardinsi An M. desjardinsi population, which was strongly female-biased in 2011 because of a high prevalence of the male-killing Spiroplasma endosymbiont, had a sex ratio near parity in 2016, despite a consistent Spiroplasma prevalence. Most of the offspring derived from individuals collected in 2016 had 1 : 1 sex ratios in subsequent generations. Contrastingly, all-female or female-biased broods appeared frequently from crossings of these female offspring with males derived from a laboratory line founded by individuals collected in 2011. These results suggest near-fixation of a nuclear suppressor against male killing in 2016 and reject the notion that a non-male-killing Spiroplasma variant has spread in the population. Consistently, no significant difference was detected in mitochondrial haplotype variation between 2011 and 2016. These findings, and earlier findings in the butterfly Hypolimnas bolina in Samoa, suggest that these quick events of male recovery occur more commonly than is generally appreciated.

RevDate: 2019-03-18
CmpDate: 2019-03-18

Cziesielski MJ, Liew YJ, Cui G, et al (2018)

Multi-omics analysis of thermal stress response in a zooxanthellate cnidarian reveals the importance of associating with thermotolerant symbionts.

Proceedings. Biological sciences, 285(1877):.

Corals and their endosymbiotic dinoflagellates of the genus Symbiodinium have a fragile relationship that breaks down under heat stress, an event known as bleaching. However, many coral species have adapted to high temperature environments such as the Red Sea (RS). To investigate mechanisms underlying temperature adaptation in zooxanthellate cnidarians we compared transcriptome- and proteome-wide heat stress response (24 h at 32°C) of three strains of the model organism Aiptasia pallida from regions with differing temperature profiles; North Carolina (CC7), Hawaii (H2) and the RS. Correlations between transcript and protein levels were generally low but inter-strain comparisons highlighted a common core cnidarian response to heat stress, including protein folding and oxidative stress pathways. RS anemones showed the strongest increase in antioxidant gene expression and exhibited significantly lower reactive oxygen species (ROS) levels in hospite However, comparisons of antioxidant gene and protein expression between strains did not show strong differences, indicating similar antioxidant capacity across the strains. Subsequent analysis of ROS production in isolated symbionts confirmed that the observed differences of ROS levels in hospite were symbiont-driven. Our findings indicate that RS anemones do not show increased antioxidant capacity but may have adapted to higher temperatures through association with more thermally tolerant symbionts.

RevDate: 2019-03-18
CmpDate: 2019-03-18

Herrera Paredes S, Gao T, Law TF, et al (2018)

Design of synthetic bacterial communities for predictable plant phenotypes.

PLoS biology, 16(2):e2003962.

Specific members of complex microbiota can influence host phenotypes, depending on both the abiotic environment and the presence of other microorganisms. Therefore, it is challenging to define bacterial combinations that have predictable host phenotypic outputs. We demonstrate that plant-bacterium binary-association assays inform the design of small synthetic communities with predictable phenotypes in the host. Specifically, we constructed synthetic communities that modified phosphate accumulation in the shoot and induced phosphate starvation-responsive genes in a predictable fashion. We found that bacterial colonization of the plant is not a predictor of the plant phenotypes we analyzed. Finally, we demonstrated that characterizing a subset of all possible bacterial synthetic communities is sufficient to predict the outcome of untested bacterial consortia. Our results demonstrate that it is possible to infer causal relationships between microbiota membership and host phenotypes and to use these inferences to rationally design novel communities.

RevDate: 2019-03-17

Sugiyama Y, Murata M, Kanetani S, et al (2019)

Towards the conservation of ectomycorrhizal fungi on endangered trees: native fungal species on Pinus amamiana are rarely conserved in trees planted ex situ.

Mycorrhiza pii:10.1007/s00572-019-00887-1 [Epub ahead of print].

Ectomycorrhizal (ECM) symbiosis is essential for the survival of both host trees and associated ECM fungi. However, during conservation activities of endangered tree species, their ECM symbionts are largely ignored. Here, we investigated ECM fungi in ex situ populations established for the conservation of Pinus amamiana, an endangered species distributed on Yakushima Island, Japan. Our objective was to determine whether ECM fungi in natural forests are conserved in ex situ populations on the same island. In particular, we focused on the existence of Rhizopogon yakushimensis, which is specific to P. amamiana and the most dominant in natural P. amamiana forests. Molecular identification of ECM fungi in resident tree roots and soil propagule banks indicated that ECM fungal species native to natural forests were rarely conserved in ex situ populations. Furthermore, R. yakushimensis was not confirmed in any of the resident root or spore bioassay samples from the ex situ populations. Thus, ECM fungal spores may not be effectively dispersed from natural forests located on the same island. Instead, ECM fungi distributed in other geographical regions occurred more frequently in the ex situ populations, indicating unintentional introductions of non-native ECM fungi from the nurseries where seedlings were raised before transplanting. These findings imply that the current ex situ conservation practices of endangered tree do not work for the conservation of native ECM fungi, and instead may need modification to avoid the risk of introducing non-native ECM fungi near the endangered forest sites.

RevDate: 2019-03-16

Frank AC (2019)

Molecular host mimicry and manipulation in bacterial symbionts.

FEMS microbiology letters, 366(4):.

It is common among intracellular bacterial pathogens to use eukaryotic-like proteins that mimic and manipulate host cellular processes to promote colonization and intracellular survival. Eukaryotic-like proteins are bacterial proteins with domains that are rare in bacteria, and known to function in the context of a eukaryotic cell. Such proteins can originate through horizontal gene transfer from eukaryotes or, in the case of simple repeat proteins, through convergent evolution. Recent studies of microbiomes associated with several eukaryotic hosts suggest that similar molecular strategies are deployed by cooperative bacteria that interact closely with eukaryotic cells. Some mimics, like ankyrin repeats, leucine rich repeats and tetratricopeptide repeats are shared across diverse symbiotic systems ranging from amoebae to plants, and may have originated early, or evolved independently in multiple systems. Others, like plant-mimicking domains in members of the plant microbiome are likely to be more recent innovations resulting from horizontal gene transfer from the host, or from microbial eukaryotes occupying the same host. Host protein mimics have only been described in a limited set of symbiotic systems, but are likely to be more widespread. Systematic searches for eukaryote-like proteins in symbiont genomes could lead to the discovery of novel mechanisms underlying host-symbiont interactions.

RevDate: 2019-03-16

De Meyer F, Danneels B, Acar T, et al (2019)

Adaptations and evolution of a heritable leaf nodule symbiosis between Dioscorea sansibarensis and Orrella dioscoreae.

The ISME journal pii:10.1038/s41396-019-0398-8 [Epub ahead of print].

Various plant species establish intimate symbioses with bacteria within their aerial organs. The bacteria are contained within nodules or glands often present in distinctive patterns on the leaves in what is commonly referred to as leaf nodule symbiosis. We describe here a highly specific symbiosis between a wild yam species from Madagascar, Dioscorea sansibarensis and bacteria of the species Orrella dioscoreae. Using whole-genome sequencing of plastids and bacteria from wild-collected samples, we show phylogenetic patterns consistent with a dominant vertical mode of transmission of the symbionts. Unique so far among leaf nodule symbioses, the bacteria can be cultured and are amenable to comparative transcriptomics, revealing a potential role in complementing the host's arsenal of secondary metabolites. We propose a recent establishment of a vertical mode of transmission in this symbiosis which, together with a large effective population size explains the cultivability and apparent lack of genome reductive evolution in O. dioscoreae. We leverage these unique features to reveal pathways and functions under positive selection in these specialized endophytes, highlighting the candidate mechanisms enabling a permanent association in the phyllosphere.

RevDate: 2019-03-16

Adler PH, GW Courtney (2019)

Ecological and Societal Services of Aquatic Diptera.

Insects, 10(3): pii:insects10030070.

More than any other group of macro-organisms, true flies (Diptera) dominate the freshwater environment. Nearly one-third of all flies-roughly 46,000 species-have some developmental connection with an aquatic environment. Their abundance, ubiquity, and diversity of adaptations to the aquatic environment position them as major drivers of ecosystem processes and as sources of products and bioinspiration for the benefit of human society. Larval flies are well represented as ecosystem engineers and keystone species that alter the abiotic and biotic environments through activities such as burrowing, grazing, suspension feeding, and predation. The enormous populations sometimes achieved by aquatic flies can provide the sole or major dietary component for other organisms. Harnessing the services of aquatic Diptera for human benefit depends on the ingenuity of the scientific community. Aquatic flies have played a role as indicators of water quality from the earliest years of bioassessment. They serve as indicators of historical and future ecological and climate change. As predators and herbivores, they can serve as biological control agents. The association of flies with animal carcasses in aquatic environments provides an additional set of tools for forensic science. The extremophilic attributes of numerous species of Diptera offer solutions for human adaptation to harsh terrestrial and extraterrestrial environments. The potential pharmaceutical and industrial applications of the symbiotic microbial community in extremophilic Diptera are better explored than are those of dipteran chemistry. Many flies provide valuable ecological and human services as aquatic immatures, but are also pests and vectors of disease agents as terrestrial adults. The scientific community, thus, is challenged with balancing the benefits and costs of aquatic Diptera, while maintaining sustainable populations as more species face extinction.

RevDate: 2019-03-15

Rípodas C, Castaingts M, Clúa J, et al (2019)

The PvNF-YA1 and PvNF-YB7 Subunits of the Heterotrimeric NF-Y Transcription Factor Influence Strain Preference in the Phaseolus vulgaris-Rhizobium etli Symbiosis.

Frontiers in plant science, 10:221.

Transcription factors of the Nuclear Factor Y (NF-Y) family play essential functions in plant development and plasticity, including the formation of lateral root organs such as lateral root and symbiotic nodules. NF-Ys mediate transcriptional responses by acting as heterotrimers composed of three subunits, NF-YA, NF-YB, and NF-YC, which in plants are encoded by relatively large gene families. We have previously shown that, in the Phaseolus vulgaris × Rhizobium etli interaction, the PvNF-YC1 subunit is involved not only in the formation of symbiotic nodules, but also in the preference exhibited by the plant for rhizobial strains that are more efficient and competitive in nodule formation. PvNF-YC1 forms a heterotrimer with the PvNF-YA1 and PvNF-YB7 subunits. Here, we used promoter:reporter fusions to show that both PvNF-YA1 and PvNF-YB7 are expressed in symbiotic nodules. In addition, we report that knock-down of PvNF-YA1 and its close paralog PvNF-YA9 abolished nodule formation by either high or low efficient strains and arrested rhizobial infection. On the other hand, knock-down of PvNF-YB7 only affected the symbiotic outcome of the high efficient interaction, suggesting that other symbiotic NF-YB subunits might be involved in the more general mechanisms of nodule formation. More important, we present functional evidence supporting that both PvNF-YA1 and PvNF-YB7 are part of the mechanisms that allow P. vulgaris plants to discriminate and select those bacterial strains that perform better in nodule formation, most likely by acting in the same heterotrimeric complex that PvNF-YC1.

RevDate: 2019-03-15

Skiada V, Faccio A, Kavroulakis N, et al (2019)

Colonization of Legumes by an Endophytic Fusarium solani strain FsK Reveals Common Features to Symbionts or Pathogens.

Fungal genetics and biology : FG & B pii:S1087-1845(18)30255-X [Epub ahead of print].

Plant cellular responses to endophytic filamentous fungi are scarcely reported, with the majority of described colonization processes in plant-fungal interactions referring to either pathogens or true symbionts. Fusarium solani strain K (FsK) is a root endophyte of Solanum lycopersicum, which protects against root and foliar pathogens. Here, we investigated the association of FsK with two legumes (Lotus japonicus and Medicago truncatula) and report on colonization patterns and plant responses during the establishment of the interaction. L. japonicus plants colonized by FsK complete their life cycle and exhibit no apparent growth defects under normal conditions. We followed the growth of FsK within root-inoculated plants spatiotemporally and showed the capability of the endophyte to migrate to the stem. In a bipartite system comprising of the endophyte and either whole plants or root organ cultures, we studied the plant sub-cellular responses to FsK recognition, using optical, confocal and transmission electron microscopy. A polarized reorganization of the root cell occurs: endoplasmic reticulum/cytoplasm accumulation and nuclear placement at contact sites, occasional development of papillae underneath hyphopodia and membranous material rearrangements towards penetrating hyphae. Fungal hyphae proliferate within the vascular bundle of the plant. Plant cell death is involved in fungal colonization of the root. Our data suggest that the establishment of FsK within legume tissues requires fungal growth adaptations and plant cell-autonomous responses, known to occur during both symbiotic and pathogenic plant-fungal interactions. We highlight the overlooked plasticity of endophytic fungi upon plant colonization, and introduce a novel plant-endophyte association.

RevDate: 2019-03-15
CmpDate: 2019-03-15

Campbell MA, Łukasik P, Meyer MC, et al (2018)

Changes in Endosymbiont Complexity Drive Host-Level Compensatory Adaptations in Cicadas.

mBio, 9(6):.

For insects that depend on one or more bacterial endosymbionts for survival, it is critical that these bacteria are faithfully transmitted between insect generations. Cicadas harbor two essential bacterial endosymbionts, "Candidatus Sulcia muelleri" and "Candidatus Hodgkinia cicadicola." In some cicada species, Hodgkinia has fragmented into multiple distinct but interdependent cellular and genomic lineages that can differ in abundance by more than two orders of magnitude. This complexity presents a potential problem for the host cicada, because low-abundance but essential Hodgkinia lineages risk being lost during the symbiont transmission bottleneck from mother to egg. Here we show that all cicada eggs seem to receive the full complement of Hodgkinia lineages, and that in cicadas with more complex Hodgkinia this outcome is achieved by increasing the number of Hodgkinia cells transmitted by up to 6-fold. We further show that cicada species with varying Hodgkinia complexity do not visibly alter their transmission mechanism at the resolution of cell biological structures. Together these data suggest that a major cicada adaptation to changes in endosymbiont complexity is an increase in the number of Hodgkinia cells transmitted to each egg. We hypothesize that the requirement to increase the symbiont titer is one of the costs associated with Hodgkinia fragmentation.IMPORTANCE Sap-feeding insects critically rely on one or more bacteria or fungi to provide essential nutrients that are not available at sufficient levels in their diets. These microbes are passed between insect generations when the mother places a small packet of microbes into each of her eggs before it is laid. We have previously described an unusual lineage fragmentation process in a nutritional endosymbiotic bacterium of cicadas called Hodgkinia In some cicadas, a single Hodgkinia lineage has split into numerous related lineages, each performing a subset of original function and therefore each required for normal host function. Here we test how this splitting process affects symbiont transmission to eggs. We find that cicadas dramatically increase the titer of Hodgkinia cells passed to each egg in response to lineage fragmentation, and we hypothesize that this increase in bacterial cell count is one of the major costs associated with endosymbiont fragmentation.

RevDate: 2019-03-15
CmpDate: 2019-03-15

Kothe E (2018)

Special Focus: Actinobacteria.

Journal of basic microbiology, 58(9):719.

RevDate: 2019-03-15
CmpDate: 2019-03-15

Burks D, Azad R, Wen J, et al (2018)

The Medicago truncatula Genome: Genomic Data Availability.

Methods in molecular biology (Clifton, N.J.), 1822:39-59.

Medicago truncatula emerged in 1990 as a model for legumes, comprising the third largest land plant family. Most legumes form symbiotic nitrogen-fixing root nodules with compatible soil bacteria and thus are important contributors to the global nitrogen cycle and sustainable agriculture. Legumes and legume products are important sources for human and animal protein as well as for edible and industrial oils. In the years since M. truncatula was chosen as a legume model, many genetic, genomic, and molecular resources have become available, including reference quality genome sequences for two widely used genotypes. Accessibility of genomic data is important for many different types of studies with M. truncatula as well as for research involving crop and forage legumes. In this chapter, we discuss strategies to obtain archived M. truncatula genomic data originally deposited into custom databases that are no longer maintained but are now accessible in general databases. We also review key current genomic databases that are specific to M. truncatula as well as those that contain M. truncatula data in addition to data from other plants.

RevDate: 2019-03-15
CmpDate: 2019-03-15

Ranjbar Jafarabadi A, Riyahi Bakhtiari A, Maisano M, et al (2018)

First record of bioaccumulation and bioconcentration of metals in Scleractinian corals and their algal symbionts from Kharg and Lark coral reefs (Persian Gulf, Iran).

The Science of the total environment, 640-641:1500-1511.

Metal pollution is nowadays a serious threat worldwide for ecosystem and human health. Despite that, there is still a paucity of data on metal impact on coral reef ecosystems. Herein, the levels of eleven metals (Mn, Zn, Cu, Cr, Co, Ni, V, As, Cd, Hg, Pb) were assessed in surface sediments, seawater samples, Scleractinian corals (tissue and skeleton) and their algal symbionts collected from Kharg and Lark coral reefs in the Persian Gulf, Iran. At Kharg, surface sediments and seawater showed higher concentrations of metals than Lark, attributable to the higher metal loads and petrochemical activities in the area. Sediment quality guidelines indicated Hg as a serious threat to biota both at Kharg and Lark. Accordingly, metals bioaccumulation and bioconcentration was higher in corals from Kharg relatively to Lark Island. Interestingly, as supported by values of BCFs and BSAFs, metal accumulation was higher in coral tissues in respect to skeletons, and in zooxanthellae relatively to coral tissues at both coral reefs. Differential metal bioaccumulation was found among Scleractinian species, indicating that corals have distinct selectivity for assimilating metals from ambient sediments and seawater. Overall, metal accumulation in corals and zooxanthellae is an appropriate tool for environmental monitoring studies in coral reefs. Noteworthy, the use of Porites lutea, among Scleractinian corals, seems to be as a good bioindicator in monitoring studies of metal pollution.

RevDate: 2019-03-15
CmpDate: 2019-03-15

Liu Z (2018)

Microbes and host dance in harmony or disarray?.

Protein & cell, 9(5):395-396.

RevDate: 2019-03-14

Shinde S, Prasad S, Saboo Y, et al (2019)

Predictive markers for Parkinson's disease using deep neural nets on neuromelanin sensitive MRI.

NeuroImage. Clinical, 22:101748 pii:S2213-1582(19)30098-1 [Epub ahead of print].

Neuromelanin sensitive magnetic resonance imaging (NMS-MRI) has been crucial in identifying abnormalities in the substantia nigra pars compacta (SNc) in Parkinson's disease (PD) as PD is characterized by loss of dopaminergic neurons in the SNc. Current techniques employ estimation of contrast ratios of the SNc, visualized on NMS-MRI, to discern PD patients from the healthy controls. However, the extraction of these features is time-consuming and laborious and moreover provides lower prediction accuracies. Furthermore, these do not account for patterns of subtle changes in PD in the SNc. To mitigate this, our work establishes a computer-based analysis technique that uses convolutional neural networks (CNNs) to create prognostic and diagnostic biomarkers of PD from NMS-MRI. Our technique not only performs with a superior testing accuracy (80%) as compared to contrast ratio-based classification (56.5% testing accuracy) and radiomics classifier (60.3% testing accuracy), but also supports discriminating PD from atypical parkinsonian syndromes (85.7% test accuracy). Moreover, it has the capability to locate the most discriminative regions on the neuromelanin contrast images. These discriminative activations demonstrate that the left SNc plays a key role in the classification in comparison to the right SNc, and are in agreement with the concept of asymmetry in PD. Overall, the proposed technique has the potential to support radiological diagnosis of PD while facilitating deeper understanding into the abnormalities in SNc.

RevDate: 2019-03-14

Bruand C, E Meilhoc (2019)

NO in plants: pro or anti senescence.

Journal of experimental botany pii:5380416 [Epub ahead of print].

Senescence is a regulated process of tissue degeneration which concerns any plant organ and consists in the degradation and remobilization of molecules to other growing tissues. Senescent organs display microscopic changes as well as internal cellular structure modifications and differential gene expression. A large number of factors influencing senescence have been described including age, nutrient supply and environmental interactions. Internal factors such as phytohormones also affect the timing of leaf senescence. A link between the senescence process and nitric oxide (NO) production in senescing tissues has been noticed for many years. Astonishingly, this link proves to be either a positive or a negative correlation depending upon the organ. NO is a gas signaling or a toxic molecule known to have multiple roles in plants; this review discusses the duality of NO roles in the senescence process of two different plant organs, leaves and root nodules.

RevDate: 2019-03-14

Dick GJ (2019)

The microbiomes of deep-sea hydrothermal vents: distributed globally, shaped locally.

Nature reviews. Microbiology pii:10.1038/s41579-019-0160-2 [Epub ahead of print].

The discovery of chemosynthetic ecosystems at deep-sea hydrothermal vents in 1977 changed our view of biology. Chemosynthetic bacteria and archaea form the foundation of vent ecosystems by exploiting the chemical disequilibrium between reducing hydrothermal fluids and oxidizing seawater, harnessing this energy to fix inorganic carbon into biomass. Recent research has uncovered fundamental aspects of these microbial communities, including their relationships with underlying geology and hydrothermal geochemistry, interactions with animals via symbiosis and distribution both locally in various habitats within vent fields and globally across hydrothermal systems in diverse settings. Although 'black smokers' and symbioses between microorganisms and macrofauna attract much attention owing to their novelty and the insights they provide into life under extreme conditions, habitats such as regions of diffuse flow, subseafloor aquifers and hydrothermal plumes have important roles in the global cycling of elements through hydrothermal systems. Owing to sharp contrasts in physical and chemical conditions between these various habitats and their dynamic, extreme and geographically isolated nature, hydrothermal vents provide a valuable window into the environmental and ecological forces that shape microbial communities and insights into the limits, origins and evolution of microbial life.

RevDate: 2019-03-14
CmpDate: 2019-03-14

Nobbs A, J Kreth (2019)

Genetics of sanguinis-Group Streptococci in Health and Disease.

Microbiology spectrum, 7(1):.

With the application of increasingly advanced "omics" technologies to the study of our resident oral microbiota, the presence of a defined, health-associated microbial community has been recognized. Within this community, sanguinis-group streptococci, comprising the closely related Streptococcus sanguinis and Streptococcus gordonii, together with Streptococcus parasanguinis, often predominate. Their ubiquitous and abundant nature reflects the evolution of these bacteria as highly effective colonizers of the oral cavity. Through interactions with host tissues and other microbes, and the capacity to readily adapt to prevailing environmental conditions, sanguinis-group streptococci are able to shape accretion of the oral plaque biofilm and promote development of a microbial community that exists in harmony with its host. Nonetheless, upon gaining access to the blood stream, those very same colonization capabilities can confer upon sanguinis-group streptococci the ability to promote systemic disease. This article focuses on the role of sanguinis-group streptococci as the commensurate commensals, highlighting those aspects of their biology that enable the coordination of health-associated biofilm development. This includes the molecular mechanisms, both synergistic and antagonistic, that underpin adhesion to substrata, intercellular communication, and polymicrobial community formation. As our knowledge of these processes advances, so will the opportunities to exploit this understanding for future development of novel strategies to control oral and extraoral disease.

RevDate: 2019-03-14
CmpDate: 2019-03-14

Litvak Y, Mon KKZ, Nguyen H, et al (2019)

Commensal Enterobacteriaceae Protect against Salmonella Colonization through Oxygen Competition.

Cell host & microbe, 25(1):128-139.e5.

Neonates are highly susceptible to infection with enteric pathogens, but the underlying mechanisms are not resolved. We show that neonatal chick colonization with Salmonella enterica serovar Enteritidis requires a virulence-factor-dependent increase in epithelial oxygenation, which drives pathogen expansion by aerobic respiration. Co-infection experiments with an Escherichia coli strain carrying an oxygen-sensitive reporter suggest that S. Enteritidis competes with commensal Enterobacteriaceae for oxygen. A combination of Enterobacteriaceae and spore-forming bacteria, but not colonization with either community alone, confers colonization resistance against S. Enteritidis in neonatal chicks, phenocopying germ-free mice associated with adult chicken microbiota. Combining spore-forming bacteria with a probiotic E. coli isolate protects germ-free mice from pathogen colonization, but the protection is lost when the ability to respire oxygen under micro-aerophilic conditions is genetically ablated in E. coli. These results suggest that commensal Enterobacteriaceae contribute to colonization resistance by competing with S. Enteritidis for oxygen, a resource critical for pathogen expansion.

RevDate: 2019-03-14
CmpDate: 2019-03-14

Chen EC, Mathieu S, Hoffrichter A, et al (2018)

Single nucleus sequencing reveals evidence of inter-nucleus recombination in arbuscular mycorrhizal fungi.

eLife, 7: pii:39813.

Eukaryotes thought to have evolved clonally for millions of years are referred to as ancient asexuals. The oldest group among these are the arbuscular mycorrhizal fungi (AMF), which are plant symbionts harboring hundreds of nuclei within one continuous cytoplasm. Some AMF strains (dikaryons) harbor two co-existing nucleotypes but there is no direct evidence that such nuclei recombine in this life-stage, as is expected for sexual fungi. Here, we show that AMF nuclei with distinct genotypes can undergo recombination. Inter-nuclear genetic exchange varies in frequency among strains, and despite recombination all nuclear genomes have an average similarity of at least 99.8%. The present study demonstrates that AMF can generate genetic diversity via meiotic-like processes in the absence of observable mating. The AMF dikaryotic life-stage is a primary source of nuclear variability in these organisms, highlighting its potential for strain enhancement of these symbionts.

RevDate: 2019-03-14
CmpDate: 2019-03-14

Ruocco N, Mutalipassi M, Pollio A, et al (2018)

First evidence of Halomicronema metazoicum (Cyanobacteria) free-living on Posidonia oceanica leaves.

PloS one, 13(10):e0204954.

Cyanobacteria contribute to the ecology of various marine environments, also for their symbioses, since some of them are common hosts of sponges and ascidians. They are also emerging as an important source of novel bioactive secondary metabolites in pharmacological (as anticancer drugs) and biotechnological applications. In the present work we isolated a cyanobacteria in a free-living state from leaves of the seagrass Posidonia oceanica leaves. This newly collected strain was then cultivated under two laboratory conditions, and then characterized by combining morphological observation and molecular studies based on 16S rRNA gene sequences analysis. The strain showed 99% pairwise sequence identity with Halomicronema metazoicum ITAC101, never isolated before as a free-living organisms, but firstly described as an endosymbiont of the Mediterranean marine spongae Petrosia ficiformis, under the form of a filamentous strain. Further studies will investigate the actual role of this cyanobacterium in the leaf stratum of P. oceanica leaves, given its demonstrated ability to influence the vitality and the life cycle of other organisms. In fact, its newly demonstrated free-living stage, described in this study, indicate that Phormidium-like cyanobacteria could play important roles in the ecology of benthic and planktonic communities.

RevDate: 2019-03-14
CmpDate: 2019-03-14

Nagy LG (2018)

Many roads to convergence.

Science (New York, N.Y.), 361(6398):125-126.

RevDate: 2019-03-14
CmpDate: 2019-03-14

Morrow KM, Tedford AR, Pankey MS, et al (2018)

A member of the Roseobacter clade, Octadecabacter sp., is the dominant symbiont in the brittle star Amphipholis squamata.

FEMS microbiology ecology, 94(4):.

Symbiotic associations with subcuticular bacteria (SCB) have been identified and studied in many echinoderms, including the SCB of the brooding brittle star, Amphipholis squamata. Previous studies on the SCB of A. squamata placed the isolated bacterium, designated as AS1, in the genus Vibrio (Gammaproteobacteria), but subsequent studies suggested that the SCB of echinoderms belong to the Alphaproteobacteria. This study examines the taxonomic composition of SCB associated with A. squamata from the Northwest Atlantic using the 16S rRNA gene and next generation sequencing. Results show the presence of a single dominant bacterial type, within the Roseobacter clade, family Rhodobacteraceae, which composes 70%-80% of the A. squamata microbiome. These Rhodobacteraceae sequences were identified as members of the genus Octadecabacter. Additionally, the original isolate, AS1, from the brittle star A. squamata also belongs in the genus Octadecabacter based on Sanger sequencing of cloned 16S rRNA gene sequences. By comparison, adjacent seawater and sediment porewater communities were significantly more diverse, hosting bacteria in the phyla Proteobacteria, Bacteroidetes, Cyanobacteria, Verrucomicrobia and Actinobacteria. Thus, a distinct SCB community is present in A. squamata that is dominated by a member of the genus Octadecabacter and is identical to the original isolate, AS1, from this brittle star.

RevDate: 2019-03-14
CmpDate: 2019-03-14

Zélé F, Santos I, Olivieri I, et al (2018)

Endosymbiont diversity and prevalence in herbivorous spider mite populations in South-Western Europe.

FEMS microbiology ecology, 94(4):.

Bacterial endosymbionts are known as important players of the evolutionary ecology of their hosts. However, their distribution, prevalence and diversity are still largely unexplored. To this aim, we investigated infections by the most common bacterial reproductive manipulators in herbivorous spider mites of South-Western Europe. Across 16 populations belonging to three Tetranychus species, Wolbachia was the most prevalent (ca. 61%), followed by Cardinium (12%-15%), while only few individuals were infected by Rickettsia (0.9%-3%), and none carried Arsenophonus or Spiroplasma. These endosymbionts are here reported for the first time in Tetranychus evansi and Tetranychus ludeni, and showed variable infection frequencies between and within species, with several cases of coinfections. Moreover, Cardinium was more prevalent in Wolbachia-infected individuals, which suggests facilitation between these symbionts. Finally, sequence comparisons revealed no variation of the Wolbachia wsp and Rickettsia gtlA genes, but some diversity of the Cardinium 16S rRNA, both between and within populations of the three mite species. Some of the Cardinium sequences identified belonged to distantly-related clades, and the lack of association between these sequences and spider mite mitotypes suggests repeated host switching of Cardinium. Overall, our results reveal a complex community of symbionts in this system, opening the path for future studies.

RevDate: 2019-03-13

Sinha A, Li Z, Sun L, et al (2019)

Complete Genome Sequence of the Wolbachia wAlbB Endosymbiont of Aedes albopictus.

Genome biology and evolution, 11(3):706-720.

Wolbachia, an alpha-proteobacterium closely related to Rickettsia, is a maternally transmitted, intracellular symbiont of arthropods and nematodes. Aedes albopictus mosquitoes are naturally infected with Wolbachia strains wAlbA and wAlbB. Cell line Aa23 established from Ae. albopictus embryos retains only wAlbB and is a key model to study host-endosymbiont interactions. We have assembled the complete circular genome of wAlbB from the Aa23 cell line using long-read PacBio sequencing at 500× median coverage. The assembled circular chromosome is 1.48 megabases in size, an increase of more than 300 kb over the published draft wAlbB genome. The annotation of the genome identified 1,205 protein coding genes, 34 tRNA, 3 rRNA, 1 tmRNA, and 3 other ncRNA loci. The long reads enabled sequencing over complex repeat regions which are difficult to resolve with short-read sequencing. Thirteen percent of the genome comprised insertion sequence elements distributed throughout the genome, some of which cause pseudogenization. Prophage WO genes encoding some essential components of phage particle assembly are missing, while the remainder are found in five prophage regions/WO-like islands or scattered around the genome. Orthology analysis identified a core proteome of 535 orthogroups across all completed Wolbachia genomes. The majority of proteins could be annotated using Pfam and eggNOG analyses, including ankyrins and components of the Type IV secretion system. KEGG analysis revealed the absence of five genes in wAlbB which are present in other Wolbachia. The availability of a complete circular chromosome from wAlbB will enable further biochemical, molecular, and genetic analyses on this strain and related Wolbachia.

RevDate: 2019-03-13
CmpDate: 2019-03-13

Kamaruzaman NAC, Mašán P, Velásquez Y, et al (2018)

Macrocheles species (Acari: Macrochelidae) associated with human corpses in Europe.

Experimental & applied acarology, 76(4):453-471.

The biology of macrochelid mites might offer new venues for the interpretation of the environmental conditions surrounding human death and decomposition. Three human corpses, one from Sweden and two from Spain, have been analysed for the occurrence of Macrochelidae species. Macrocheles muscaedomesticae (Scopoli) females were associated with a corpse that was found in a popular beach area of southeast Spain. Their arrival coincides with the occurrence of one of their major carrier species, the filth fly Fannia scalaris, the activity of which peaks during mid-summer. Macrocheles glaber (Müller) specimens were collected from a corpse in a shallow grave in a forest in Sweden at the end of summer, concurrent with the arrival of beetles attracted by odours from the corpse. Macrocheles perglaber Filipponi and Pegazzano adults were sampled from a corpse found indoors in the rural surroundings of Granada city, south Spain. The phoretic behaviour of this species is similar to that of M. glaber, but it is more specific to Scarabaeidae and Geotrupidae dung beetles, most of which favour human faeces. Macrocheles muscaedomesticae is known from urban and rural areas and poultry farms, M. glaber from outdoors, particularly the countryside, whereas M. perglaber is known from outdoor, rural, and remote, potentially mountainous locations. Macrocheles muscaedomesticae and M. perglaber are reported for the first time from the Iberian Peninsula. This is the first record of M. perglaber from human remains.

RevDate: 2019-03-13
CmpDate: 2019-03-13

Saccon E, Vitiello A, Trevisan M, et al (2018)

Sixth European Seminar in Virology on Virus⁻Host Interaction at Single Cell and Organism Level.

Viruses, 10(8):.

The 6th European Seminar in Virology (EuSeV) was held in Bertinoro, Italy, 22⁻24 June 2018, and brought together international scientists and young researchers working in the field of Virology. Sessions of the meeting included: virus⁻host-interactions at organism and cell level; virus evolution and dynamics; regulation; immunity/immune response; and disease and therapy. This report summarizes lectures by the invited speakers and highlights advances in the field.

RevDate: 2019-03-12

Barros-Carvalho GA, Hungria M, Lopes FM, et al (2019)

Brazilian-adapted soybean Bradyrhizobium strains uncover IS elements with potential impact on biological nitrogen fixation.

FEMS microbiology letters pii:5376497 [Epub ahead of print].

Bradyrhizobium diazoefficiens CPAC 7 and Bradyrhizobium japonicum CPAC 15 are broadly used in commercial inoculants in Brazil, contributing to most of the nitrogen required by the soybean crop. These strains differ in their symbiotic properties: CPAC 7 is more efficient in fixing nitrogen, whereas CPAC 15 is more competitive. Comparative genomics revealed many transposases close to genes associated with symbiosis in the symbiotic island of these strains. Given the importance that Insertion Sequences (ISs) elements have to bacterial genomes, we focused on identifying the local impact of these elements in the genomes of these and other related Bradyrhizobium strains to further understand their phenotypic differences. Analyses were performed using bioinformatics approaches. We found IS elements disrupting and inserted at regulatory regions of genes involved in symbiosis. Further comparative analyses with 21 Bradyrhizobium genomes revealed insertional polymorphism with distinguishing patterns between B. diazoefficiens and B. japonicum lineages. Finally, 13 of these potentially impacted genes are differentially expressed under symbiotic conditions in B. diazoefficiens USDA 110. Thus, IS elements are associated with the diversity of Bradyrhizobium, possibly by providing mechanisms for natural variation of symbiotic effectiveness.

RevDate: 2019-03-12

Brinker P, Fontaine MC, Beukeboom LW, et al (2019)

Host, Symbionts, and the Microbiome: The Missing Tripartite Interaction.

Trends in microbiology pii:S0966-842X(19)30040-X [Epub ahead of print].

Symbiosis between microbial associates and a host is a ubiquitous feature of life on earth, modulating host phenotypes. In addition to endosymbionts, organisms harbour a collection of host-associated microbes, the microbiome that can impact important host traits. In this opinion article we argue that the mutual influences of the microbiome and endosymbionts, as well as their combined influence on the host, are still understudied. Focusing on the endosymbiont Wolbachia, we present growing evidence indicating that host phenotypic effects are exerted in interaction with the remainder microbiome and the host. We thus advocate that only through an integrated approach that considers multiple interacting partners and environmental influences will we be able to gain a better understanding of host-microbe associations.

RevDate: 2019-03-12

Sańko-Sawczenko I, Łotocka B, Mielecki J, et al (2019)

Transcriptomic Changes in Medicago truncatula and Lotus japonicus Root Nodules during Drought Stress.

International journal of molecular sciences, 20(5): pii:ijms20051204.

Drought is one of the major environmental factors limiting biomass and seed yield production in agriculture. In this research, we focused on plants from the Fabaceae family, which has a unique ability for the establishment of symbiosis with nitrogen-fixing bacteria, and are relatively susceptible to water limitation. We have presented the changes in nitrogenase activity and global gene expression occurring in Medicagotruncatula and Lotusjaponicus root nodules during water deficit. Our results proved a decrease in the efficiency of nitrogen fixation, as well as extensive changes in plant and bacterial transcriptomes, shortly after watering cessation. We showed for the first time that not only symbiotic plant components but also Sinorhizobiummeliloti and Mesorhizobiumloti bacteria residing in the root nodules of M. truncatula and L. japonicus, respectively, adjust their gene expression in response to water shortage. Although our results demonstrated that both M. truncatula and L.japonicus root nodules were susceptible to water deprivation, they indicated significant differences in plant and bacterial response to drought between the tested species, which might be related to the various types of root nodules formed by these species.

RevDate: 2019-03-12
CmpDate: 2019-03-12

Kumawat KC, Sharma P, Sirari A, et al (2019)

Synergism of Pseudomonas aeruginosa (LSE-2) nodule endophyte with Bradyrhizobium sp. (LSBR-3) for improving plant growth, nutrient acquisition and soil health in soybean.

World journal of microbiology & biotechnology, 35(3):47 pii:10.1007/s11274-019-2622-0.

The present study was aimed to assess the scope of native potential endophyte Pseudomonas aeruginosa (LSE-2) strain (KX925973) with recommended Bradyrhizobium sp. (LSBR-3) (KF906140) for synergistic effect to develop as consortium biofertilizer of soybean. A total of 28 non-rhizobial endophytic bacteria were isolated from cultivated and wild sp. of soybean. All isolates were screened for multifarious PGP traits viz. Indole-3-acetic acid (IAA), phosphate (P) and zinc (Zn) solubilization, siderophore, cell wall degrading enzymes and pathogenicity. Compatible of LSBR-3 and LSE-2 enhanced IAA, P-solubilization, 1-aminocyclopropane-carboxylate deaminase and biofilm formation over the single inoculant treatment. Further, consortium was evaluated in vivo for growth, symbiotic traits, nutrient acquisition, soil quality parameters and yield attributes of soybean. Improvement in growth parameters were recorded with dual inoculant LSBR-3 + LSE-2 as compared to LSBR-3 alone and un-inoculated control treatments. Significantly (p ≥ 0.05) high symbiotic and soil quality parameters (phosphatase and soil dehydrogenase activity) was recorded with LSBR-3 + LSE-2 at vegetative and flowering stage as compared to LSBR-3 alone and un-inoculated control treatments. Single inoculation of LSBR-3 improved grain yield by 4.25% over the un-inoculated control treatment, further, enhancement in yield was recorded with consortium inoculant (LSBR-3 and LSE-2) by 3.47% over the LSBR-3 alone. Application of consortium inoculant (LSBR-3 + LSE-2) gave an additional income of Rs. 5089/ha over the un-inoculated control treatment. The results, thus strongly suggest that endophytic diazotroph LSE-2 can be used as potent bio-inoculant along with LSBR-3 as bio-enhancer for improving soybean productivity in a sustainable system.

RevDate: 2019-03-12
CmpDate: 2019-03-12

Sapountzis P, Zhukova M, Shik JZ, et al (2018)

Reconstructing the functions of endosymbiotic Mollicutes in fungus-growing ants.

eLife, 7:.

Mollicutes, a widespread class of bacteria associated with animals and plants, were recently identified as abundant abdominal endosymbionts in healthy workers of attine fungus-farming leaf-cutting ants. We obtained draft genomes of the two most common strains harbored by Panamanian fungus-growing ants. Reconstructions of their functional significance showed that they are independently acquired symbionts, most likely to decompose excess arginine consistent with the farmed fungal cultivars providing this nitrogen-rich amino-acid in variable quantities. Across the attine lineages, the relative abundances of the two Mollicutes strains are associated with the substrate types that foraging workers offer to fungus gardens. One of the symbionts is specific to the leaf-cutting ants and has special genomic machinery to catabolize citrate/glucose into acetate, which appears to deliver direct metabolic energy to the ant workers. Unlike other Mollicutes associated with insect hosts, both attine ant strains have complete phage-defense systems, underlining that they are actively maintained as mutualistic symbionts.

RevDate: 2019-03-12
CmpDate: 2019-03-12

Cross ST, Kapuscinski ML, Perino J, et al (2018)

Co-Infection Patterns in Individual Ixodes scapularis Ticks Reveal Associations between Viral, Eukaryotic and Bacterial Microorganisms.

Viruses, 10(7):.

Ixodes scapularis ticks harbor a variety of microorganisms, including eukaryotes, bacteria and viruses. Some of these can be transmitted to and cause disease in humans and other vertebrates. Others are not pathogenic, but may impact the ability of the tick to harbor and transmit pathogens. A growing number of studies have examined the influence of bacteria on tick vector competence but the influence of the tick virome remains less clear, despite a surge in the discovery of tick-associated viruses. In this study, we performed shotgun RNA sequencing on 112 individual adult I. scapularis collected in Wisconsin, USA. We characterized the abundance, prevalence and co-infection rates of viruses, bacteria and eukaryotic microorganisms. We identified pairs of tick-infecting microorganisms whose observed co-infection rates were higher or lower than would be expected, or whose RNA levels were positively correlated in co-infected ticks. Many of these co-occurrence and correlation relationships involved two bunyaviruses, South Bay virus and blacklegged tick phlebovirus-1. These viruses were also the most prevalent microorganisms in the ticks we sampled, and had the highest average RNA levels. Evidence of associations between microbes included a positive correlation between RNA levels of South Bay virus and Borrelia burgdorferi, the Lyme disease agent. These findings contribute to the rationale for experimental studies on the impact of viruses on tick biology and vector competence.

RevDate: 2019-03-12
CmpDate: 2019-03-12

Wang F, Jing X, Adams CA, et al (2018)

Decreased ZnO nanoparticle phytotoxicity to maize by arbuscular mycorrhizal fungus and organic phosphorus.

Environmental science and pollution research international, 25(24):23736-23747.

ZnO nanoparticles (NPs) are applied in a wide variety of applications and frequently accumulate in the environment, thus posing risks to the environment and human health. Arbuscular mycorrhizal (AM) fungi (AMF) associate symbiotically with roots of most higher plants, helping their host plants acquire phosphorus (P). AMF can reduce the toxicity of ZnO NPs, but the benefits of AMF to host plants highly vary with soil available P. We hypothesize that organic P may help AMF to alleviate ZnO NP phytotoxicity. Here, we investigated the effects of inoculation with Funneliformis mosseae on plant growth and Zn accumulation, using maize grown in soil-sand mix substrates spiked with ZnO NPs (0 or 500 mg kg-1) under different organic P supply levels (0, 20, or 50 mg kg-1). The results showed addition of ZnO NPs inhibited root colonization rate, increased the shoot/root P concentration ratio, and led to significant Zn accumulation in soil and plants. As predicted, AM effects on maize plants all varied with P supply levels, both with or without ZnO NP additions. Organic P interacted synergistically with AMF to promote plant growth and acquisition of P, N, K, Fe, and Cu. AM inoculation reduced the bioavailable Zn released from ZnO NPs and decreased the concentrations and translocation of Zn to maize shoots. In conclusion, ZnO NPs caused excess Zn in soil and plants, posing potential environmental risks. However, our present results first demonstrate that organic P exhibited similar positive effects to AMF and interacted synergistically with AMF to improve plant growth and nutrition, and to decrease Zn accumulation and partitioning in plants, and thus helped diminish the adverse effects induced by ZnO NPs.

RevDate: 2019-03-12
CmpDate: 2019-03-12

Díez-Vives C, Esteves AIS, Costa R, et al (2018)

Detecting signatures of a sponge-associated lifestyle in bacterial genomes.

Environmental microbiology reports, 10(4):433-443.

Sponges interact with diverse and rich communities of bacteria that are phylogenetically often distinct from their free-living counterparts. Recent genomics and metagenomic studies have indicated that bacterial sponge symbionts also have distinct functional features from free-living bacteria; however, it is unclear, if such genome-derived functional signatures are common and present in different symbiont taxa. We therefore compared here a large set of genomes from cultured (Pseudovibrio, Ruegeria and Aquimarina) and yet-uncultivated (Synechococcus) bacteria found in either sponge-associated or free-living sources. Our analysis revealed only very few genera-specific functions that could be correlated with a sponge-associated lifestyle. Using different sets of sponge-associated and free-living bacteria for each genus, we could however show that the functions identified as 'sponge-associated' are dependent on the reference comparison being made. Using simulation approaches, we show how this influences the robustness of identifying functional signatures and how evolutionary divergence and genomic adaptation can be distinguished. Our results highlight the future need for robust comparative analyses to define genomic signatures of symbiotic lifestyles, whether it is for symbionts of sponges or other host organisms.

RevDate: 2019-03-11

Ingraffia R, Amato G, Frenda AS, et al (2019)

Impacts of arbuscular mycorrhizal fungi on nutrient uptake, N2 fixation, N transfer, and growth in a wheat/faba bean intercropping system.

PloS one, 14(3):e0213672 pii:PONE-D-18-30397.

Arbuscular mycorrhizal fungi (AMF) can play a key role in natural and agricultural ecosystems affecting plant nutrition, soil biological activity and modifying the availability of nutrients by plants. This research aimed at expanding the knowledge of the role played by AMF in the uptake of macro- and micronutrients and N transfer (using a 15N stem-labelling method) in a faba bean/wheat intercropping system. It also investigates the role of AMF in biological N fixation (using the natural isotopic abundance method) in faba bean grown in pure stand and in mixture. Finally, it examines the role of AMF in driving competition and facilitation between faba bean and wheat. Durum wheat and faba bean were grown in pots (five pots per treatment) as sole crops or in mixture in the presence or absence of AMF. Root colonisation by AMF was greater in faba bean than in wheat and increased when species were mixed compared to pure stand (particularly for faba bean). Mycorrhizal symbiosis positively influenced root biomass, specific root length, and root density and increased the uptake of P, Fe, and Zn in wheat (both in pure stand and in mixture) but not in faba bean. Furthermore, AMF symbiosis increased the percentage of N derived from the atmosphere in the total N biomass of faba bean grown in mixture (+20%) but not in pure stand. Nitrogen transfer from faba bean to wheat was low (2.5-3.0 mg pot-1); inoculation with AMF increased N transfer by 20%. Overall, in terms of above- and belowground growth and uptake of nutrients, mycorrhization favoured the stronger competitor in the mixture (wheat) without negatively affecting the companion species (faba bean). Results of this study confirm the role of AMF in driving biological interactions among neighbouring plants.

RevDate: 2019-03-11

Patelunas AJ, MK Nishiguchi (2018)

Vascular architecture in the bacteriogenic light organ of Euprymna tasmanica (Cephalopoda: Sepiolidae).

Invertebrate biology : a quarterly journal of the American Microscopical Society and the Division of Invertebrate Zoology/ASZ, 137(3):240-249.

Symbiosis between southern dumpling squid, Euprymna tasmanica (Cephalopoda: Sepiolidae), and its luminescent symbiont, the bacterium Vibrio fischeri, provides an experimentally tractable system to examine interactions between the eukaryotic host and its bacterial partner. Luminescence emitted by the symbiotic bacteria provides light for the squid in a behavior termed "counter-illumination," which allows the squid to mask its shadow amidst downwelling moonlight. Although this association is beneficial, light generated from the bacteria requires large quantities of oxygen to maintain this energy-consuming reaction. Therefore, we examined the vascular network within the light organ of juveniles of E. tasmanica with and without V. fischeri. Vessel type, diameter, and location of vessels were measured. Although differences between symbiotic and aposymbiotic squid demonstrated that the presence of V. fischeri does not significantly influence the extent of vascular branching at early stages of symbiotic development, these finding do provide an atlas of blood vessel distribution in the organ. Thus, these results provide a framework to understand how beneficial bacteria influence the development of a eukaryotic closed vascular network and provide insight to the evolutionary developmental dynamics that form during mutualistic interactions.

RevDate: 2019-03-11
CmpDate: 2019-03-11

Raimundo I, Silva SG, Costa R, et al (2018)

Bioactive Secondary Metabolites from Octocoral-Associated Microbes-New Chances for Blue Growth.

Marine drugs, 16(12): pii:md16120485.

Octocorals (Cnidaria, Anthozoa Octocorallia) are magnificent repositories of natural products with fascinating and unusual chemical structures and bioactivities of interest to medicine and biotechnology. However, mechanistic understanding of the contribution of microbial symbionts to the chemical diversity of octocorals is yet to be achieved. This review inventories the natural products so-far described for octocoral-derived bacteria and fungi, uncovering a true chemical arsenal of terpenes, steroids, alkaloids, and polyketides with antibacterial, antifungal, antiviral, antifouling, anticancer, anti-inflammatory, and antimalarial activities of enormous potential for blue growth. Genome mining of 15 bacterial associates (spanning 12 genera) cultivated from Eunicella spp. resulted in the identification of 440 putative and classifiable secondary metabolite biosynthetic gene clusters (BGCs), encompassing varied terpene-, polyketide-, bacteriocin-, and nonribosomal peptide-synthase BGCs. This points towards a widespread yet uncharted capacity of octocoral-associated bacteria to synthetize a broad range of natural products. However, to extend our knowledge and foster the near-future laboratory production of bioactive compounds from (cultivatable and currently uncultivatable) octocoral symbionts, optimal blending between targeted metagenomics, DNA recombinant technologies, improved symbiont cultivation, functional genomics, and analytical chemistry are required. Such a multidisciplinary undertaking is key to achieving a sustainable response to the urgent industrial demand for novel drugs and enzyme varieties.

RevDate: 2019-03-10

Shi L, Deng X, Yang Y, et al (2019)

A Cr(VI)-tolerant strain, Pisolithus sp1, with a high accumulation capacity of Cr in mycelium and highly efficient assisting Pinus thunbergii for phytoremediation.

Chemosphere, 224:862-872 pii:S0045-6535(19)30447-3 [Epub ahead of print].

Ectomycorrhizal (ECM) fungi can improve the growth of pine trees and enhance their tolerance to heavy metal stress, and may also be useful during the afforestation and phytoremediation of polluted regions with pine trees. Hebeloma vinosophyllum (Cr(VI)-sensitive strain) and Pisolithus sp1 ((Cr(VI)-tolerant strain) were selected through liquid culture experiment, and were used in symbiosis with Japanese black pine (Pinus thunbergii) in pot experiments, to determine their potential for improving phytoremediation of Cr(VI)-contaminated soils. Our results indicated that Pisolithus sp1 also had a significantly higher accumulation of Cr than H. vinosophyllum in mycelium under the same Cr(VI) treatments in liquid culture experiment. The tolerance index of Pisolithus sp1 ECM seedlings' shoots and roots to Cr(VI) were significantly higher than that of H. vinosophyllum ECM and non-ectomycorrhizal (NM) seedlings while the total accumulated Cr per seedling in Pisolithus sp1 ECM seedlings were 1.50-1.96 and 2.83-27.75 fold higher that of H. vinosophyllum ECM and NM seedlings, respectively, within 0-800 mg kg-1 Cr(VI) treatments in pot experiments. In addition, the significant differences ratios of photosynthetic rate, stomatal conductance, transpiration rate and intercellular CO2 concentration between Pisolithus sp1 ECM and NM seedlings were significantly higher than those between H. vinosophyllum ECM and NM seedlings under 400 and 800 mg kg-1 Cr(VI) treatments. Compared with the control (no plant), and planting NM or H. vinosophyllum ECM seedlings, the planting of Pisolithus sp1 ECM seedlings significantly reduced the percentage content of exchangeable Cr in the soil.

RevDate: 2019-03-10

Hudson J, Kumar V, S Egan (2019)

Comparative genome analysis provides novel insight into the interaction of Aquimarina sp. AD1, BL5 and AD10 with their macroalgal host.

Marine genomics pii:S1874-7787(19)30003-0 [Epub ahead of print].

The Aquimarina genus is widely distributed throughout the marine environment, however little is understood regarding its ecological role, particularly when in association with eukaryotic hosts. Here, we examine the genomes of two opportunistic pathogens, Aquimarina sp. AD1 and BL5, and a non-pathogenic strain Aquimarina sp. AD10, that were isolated from diseased individuals of the red alga Delisea pulchra. Each strain encodes multiple genes for the degradation of marine carbohydrates and vitamin biosynthesis. These traits are hypothesised to promote nutrient exchange between the Aquimarina strains and their algal host, facilitating a close symbiotic relationship. Moreover, each strain harbours the necessary genes for the assembly of a Type 9 Secretion System (T9SS) and the associated gliding motility apparatus. In addition to these common features, pathogenic strains AD1 and BL5, encode genes for the production of flexirubin type pigments and a number of unique non-ribosomal peptide synthesis (NRPS) gene clusters, suggesting a role for these uncharacterised traits in virulence. This study provides valuable insight into the potential ecological role of Aquimarina in the marine environment and the complex factors driving pathogenesis and symbiosis in this genus.

RevDate: 2019-03-09

Wang L, Delgado-Baquerizo M, Wang D, et al (2019)

Diversifying livestock promotes multidiversity and multifunctionality in managed grasslands.

Proceedings of the National Academy of Sciences of the United States of America pii:1807354116 [Epub ahead of print].

Increasing plant diversity can increase ecosystem functioning, stability, and services in both natural and managed grasslands, but the effects of herbivore diversity, and especially of livestock diversity, remain underexplored. Given that managed grazing is the most extensive land use worldwide, and that land managers can readily change livestock diversity, we experimentally tested how livestock diversification (sheep, cattle, or both) influenced multidiversity (the diversity of plants, insects, soil microbes, and nematodes) and ecosystem multifunctionality (including plant biomass production, plant leaf N and P, above-ground insect abundance, nutrient cycling, soil C stocks, water regulation, and plant-microbe symbiosis) in the world's largest remaining grassland. We also considered the potential dependence of ecosystem multifunctionality on multidiversity. We found that livestock diversification substantially increased ecosystem multifunctionality by increasing multidiversity. The link between multidiversity and ecosystem multifunctionality was always stronger than the link between single diversity components and functions. Our work provides insights into the importance of multitrophic diversity to maintain multifunctionality in managed ecosystems and suggests that diversifying livestock could promote both multidiversity and ecosystem multifunctionality in an increasingly managed world.

RevDate: 2019-03-09

Pons I, Renoz F, Noël C, et al (2019)

New Insights into the Nature of Symbiotic Associations in Aphids: Infection Process, Biological Effects and Transmission Mode of Cultivable Serratia symbiotica Bacteria.

Applied and environmental microbiology pii:AEM.02445-18 [Epub ahead of print].

Symbiotic microorganisms are widespread in nature and can play a major role in the ecology and evolution of animals. The aphid-Serratia symbiotica bacterium interaction provides a valuable model to study mechanisms behind these symbiotic associations. The recent discovery of cultivable S. symbiotica strains having the possibility of free-living lifestyle allowed us to simulate their environmental acquisition by aphids to examine the mechanisms involved in this infection pathway. Here, after oral ingestion, we analyzed the infection dynamic of cultivable S. symbiotica during the host's lifetime using qPCR and fluorescence techniques and determined the immediate fitness consequences of these bacteria on their new host. We further examined the transmission behavior and phylogenetic position of cultivable strains. Our study revealed that cultivable S. symbiotica are predisposed to establish a symbiotic association with new aphid host, settling in its gut. We showed that cultivable S. symbiotica colonized the entire aphid digestive tract following infection, after which the bacterium multiplied exponentially during aphid development. Our results further revealed that gut colonization by the bacteria induces a fitness cost to their hosts. Nevertheless, it appeared that the bacteria also offer an immediate protection against parasitoids. Interestingly, cultivable S. symbiotica strains seem to be extracellularly transmitted, possibly through the honeydew; while S. symbiotica is generally considered as a maternally-transmitted bacterium living within aphid body cavity and bringing some benefits to its hosts despite its costs. These findings provide new insights into the nature of symbiosis in aphids and the mechanisms underpinning these interactions.IMPORTANCES. symbiotica is one of the most common symbionts among aphid populations and includes a wide variety of strains whose degree of interdependence on the host may vary considerably. S. symbiotica strains with free-living capacity have recently been isolated from aphids. By using these strains, we established artificial associations by simulating new bacterial acquisitions involved in aphid gut infections to decipher their infection processes and biological effects on their new hosts. Our results showed the early stages involved in this route of infection. So far, S. symbiotica was considered as a maternally-transmitted aphid endosymbiont. Nevertheless, we showed that our cultivable S. symbiotica occupy and replicate in aphid gut and seem to be transmitted over generations through an environmental transmission mechanism. Moreover, cultivable S. symbiotica are both parasites and mutualists given the context, as many of aphid endosymbionts. Our findings give new perception of associations involved in bacterial mutualism in aphids.

RevDate: 2019-03-08

Teschima MM, Garrido A, Paris A, et al (2019)

Biogeography of the endosymbiotic dinoflagellates (Symbiodiniaceae) community associated with the brooding coral Favia gravida in the Atlantic Ocean.

PloS one, 14(3):e0213519 pii:PONE-D-18-27962.

Zooxanthellate corals live in symbiosis with phototrophic dinoflagellates of the family Symbiodiniaceae, enabling the host coral to dwell in shallow, nutrient-poor marine waters. The South Atlantic Ocean is characterized by low coral diversity with high levels of endemism. However, little is known about coral-dinoflagellate associations in the region. This study examined the diversity of Symbiodiniaceae associated with the scleractinian coral Favia gravida across its distributional range using the ITS-2 marker. This brooding coral endemic to the South Atlantic can be found across a wide range of latitudes and longitudes, including the Mid-Atlantic islands. Even though it occurs primarily in shallower environments, F. gravida is among the few coral species that live in habitats with extreme environmental conditions (high irradiance, temperature, and turbidity) such as very shallow tide pools. In the present study, we show that F. gravida exhibits some degree of flexibility in its symbiotic association with zooxanthellae across its range. F. gravida associates predominantly with Cladocopium C3 (ITS2 type Symbiodinium C3) but also with Symbiodinium A3, Symbiodinium linucheae (ITS2 type A4), Cladocopium C1, Cladocopium C130, and Fugacium F3. Symbiont diversity varied across biogeographic regions (Symbiodinium A3 and S. linucheae were found in the Tropical Eastern Atlantic, Cladocopium C1 in the Mid-Atlantic, and other subtypes in the Southwestern Atlantic) and was affected by local environmental conditions. In addition, Symbiodiniaceae diversity was highest in a southwestern Atlantic oceanic island (Rocas Atoll). Understanding the relationship between corals and their algal symbionts is critical in determining the factors that control the ecological niches of zooxanthellate corals and their symbionts, and identifying host-symbiont pairs that may be more resistant to environmental changes.

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ESP Quick Facts

ESP Origins

In the early 1990's, Robert Robbins was a faculty member at Johns Hopkins, where he directed the informatics core of GDB — the human gene-mapping database of the international human genome project. To share papers with colleagues around the world, he set up a small paper-sharing section on his personal web page. This small project evolved into The Electronic Scholarly Publishing Project.

ESP Support

In 1995, Robbins became the VP/IT of the Fred Hutchinson Cancer Research Center in Seattle, WA. Soon after arriving in Seattle, Robbins secured funding, through the ELSI component of the US Human Genome Project, to create the original ESP.ORG web site, with the formal goal of providing free, world-wide access to the literature of classical genetics.

ESP Rationale

Although the methods of molecular biology can seem almost magical to the uninitiated, the original techniques of classical genetics are readily appreciated by one and all: cross individuals that differ in some inherited trait, collect all of the progeny, score their attributes, and propose mechanisms to explain the patterns of inheritance observed.

ESP Goal

In reading the early works of classical genetics, one is drawn, almost inexorably, into ever more complex models, until molecular explanations begin to seem both necessary and natural. At that point, the tools for understanding genome research are at hand. Assisting readers reach this point was the original goal of The Electronic Scholarly Publishing Project.

ESP Usage

Usage of the site grew rapidly and has remained high. Faculty began to use the site for their assigned readings. Other on-line publishers, ranging from The New York Times to Nature referenced ESP materials in their own publications. Nobel laureates (e.g., Joshua Lederberg) regularly used the site and even wrote to suggest changes and improvements.

ESP Content

When the site began, no journals were making their early content available in digital format. As a result, ESP was obliged to digitize classic literature before it could be made available. For many important papers — such as Mendel's original paper or the first genetic map — ESP had to produce entirely new typeset versions of the works, if they were to be available in a high-quality format.

ESP Help

Early support from the DOE component of the Human Genome Project was critically important for getting the ESP project on a firm foundation. Since that funding ended (nearly 20 years ago), the project has been operated as a purely volunteer effort. Anyone wishing to assist in these efforts should send an email to Robbins.

ESP Plans

With the development of methods for adding typeset side notes to PDF files, the ESP project now plans to add annotated versions of some classical papers to its holdings. We also plan to add new reference and pedagogical material. We have already started providing regularly updated, comprehensive bibliographies to the ESP.ORG site.

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Papers in Classical Genetics

The ESP began as an effort to share a handful of key papers from the early days of classical genetics. Now the collection has grown to include hundreds of papers, in full-text format.

Digital Books

Along with papers on classical genetics, ESP offers a collection of full-text digital books, including many works by Darwin (and even a collection of poetry — Chicago Poems by Carl Sandburg).

Timelines

ESP now offers a much improved and expanded collection of timelines, designed to give the user choice over subject matter and dates.

Biographies

Biographical information about many key scientists.

Selected Bibliographies

Bibliographies on several topics of potential interest to the ESP community are now being automatically maintained and generated on the ESP site.

ESP Picks from Around the Web (updated 07 JUL 2018 )