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Bibliography on: Symbiosis

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ESP: PubMed Auto Bibliography 29 May 2020 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: 2020-05-28
CmpDate: 2020-05-28

Gómez A (2019)

[Microbioma, salud y enfermedad: probióticos, prebióticos y simbióticos].

Biomedica : revista del Instituto Nacional de Salud, 39(4):617-621.

RevDate: 2020-05-28
CmpDate: 2020-05-28

Hechinger RF, Sheehan KL, AV Turner (2019)

Metabolic theory of ecology successfully predicts distinct scaling of ectoparasite load on hosts.

Proceedings. Biological sciences, 286(1917):20191777.

The impacts of parasites on hosts and the role that parasites play in ecosystems must be underlain by the load of parasites in individual hosts. To help explain and predict parasite load across a broad range of species, quantitative theory has been developed based on fundamental relationships between organism size, temperature and metabolic rate. Here, we elaborate on an aspect of that 'scaling theory for parasitism', and test a previously unexplored prediction, using new data for total ectoparasite load from 263 wild birds of 42 species. We reveal that, despite the expected substantial variation in parasite load among individual hosts, (i) the theory successfully predicts the distinct increase of ectoparasite load with host body size, indicating the importance of geometric scaling constraints on access to host resources, (ii) ectoparasite load appears ultimately limited by access-not to host space-but to host energy, and (iii) there is a currency-dependent shift in taxonomic dominance of parasite load on larger birds. Hence, these results reveal a seemingly new macroecological pattern, underscore the utility of energy flux as a currency for parasitism and highlight the promise of using scaling theory to provide baseline expectations for parasite load for a diversity of host species.

RevDate: 2020-05-28
CmpDate: 2020-05-28

Thomas L, López EH, Morikawa MK, et al (2019)

Transcriptomic resilience, symbiont shuffling, and vulnerability to recurrent bleaching in reef-building corals.

Molecular ecology, 28(14):3371-3382.

As climate change progresses and extreme temperature events increase in frequency, rates of disturbance may soon outpace the capacity of certain species of reef-building coral to recover from bleaching. This may lead to dramatic shifts in community composition and ecosystem function. Understanding variation in rates of bleaching recovery among species and how that translates to resilience to recurrent bleaching is fundamental to predicting the impacts of increasing disturbances on coral reefs globally. We tracked the response of two heat sensitive species in the genus Acropora to repeated bleaching events during the austral summers of 2015 and 2017. Despite a similar bleaching response, the species Acropora gemmifera recovered faster based on transcriptome-wide gene expression patterns and had a more dynamic algal symbiont community than Acropora hyacinthus growing on the same reef. Moreover, A. gemmifera had higher survival to repeated heat extremes, with six-fold lower mortality than A. hyacinthus. These patterns suggest that speed of recovery from a first round of bleaching, based on multiple mechanisms, contributes strongly to sensitivity to a second round of bleaching. Furthermore, our data uncovered intragenus variation in a group of corals thought generally to be heat-sensitive and therefore paint a more nuanced view of the future health of coral reef ecosystems against a backdrop of increasing thermal disturbances.

RevDate: 2020-05-28
CmpDate: 2020-05-28

Crew PE, McNamara L, Waldron PE, et al (2019)

Unusual Neisseria species as a cause of infection in patients taking eculizumab.

The Journal of infection, 78(2):113-118.

BACKGROUND: Non-meningococcal, non-gonococcal Neisseria spp. are typically commensal and rarely cause invasive disease. Eculizumab is a terminal complement inhibitor that increases susceptibility to meningococcal disease, but data on disease caused by typically-commensal Neisseria spp. are lacking. This series describes postmarketing reports of typically-commensal Neisseria spp. disease in patients receiving eculizumab.

METHODS: We searched the FDA Adverse Event Reporting System (FAERS) and medical literature for reports of commensal Neisseria spp. disease in patients receiving eculizumab, from eculizumab U.S. approval (2007) through January 31, 2018.

RESULTS: We identified seven FAERS reports (including one case also reported in the literature) of non-meningococcal, non-gonococcal Neisseria disease, including N. sicca (mucosa)/subflava (n = 2), N. cinerea (n = 2), N. sicca (mucosa) (n = 1), N. mucosa (n = 1, with concurrent alpha-hemolytic Streptococcus bacteremia), and N. flavescens (subflava) (n = 1). Four cases had sources of patient immunosuppression in addition to eculizumab. Three patients had sepsis (n = 2) or septic shock (n = 1). Five patients were bacteremic. All patients were hospitalized; the infections resolved with antibiotics.

CONCLUSIONS: Our search identified seven cases of disease from typically commensal Neisseria spp. in eculizumab recipients. These findings suggest that any Neisseria spp. identified from a normally sterile site in an eculizumab recipient could represent true infection warranting prompt treatment.

RevDate: 2020-05-27

Mesjasz-Przybyłowicz J, WJ Przybyłowicz (2020)

Ecophysiology of nickel hyperaccumulating plants from South Africa - from ultramafic soil and mycorrhiza to plants and insects.

Metallomics : integrated biometal science [Epub ahead of print].

An overview of 30 years of studies related to South African nickel hyperaccumulators is presented. Only five species have so far been identified as Ni hyperaccumulator plants among very rich and diversified South African flora. All of them occur on soils derived from ultramafic (serpentine) rocks and belong to the family Asteraceae: Berkheya coddii Roessler, Berkheya zeyheri subsp. rehmannii var. rogersiana, Berkheya nivea, Senecio coronatus, Senecio anomalochrous. Several techniques and methods were used to investigate ecophysiological aspects of the Ni hyperaccumulation phenomenon, from basic field and laboratory studies, to advanced instrumental methods. Analysis of elemental distribution in plant parts showed that in most cases the hyperaccumulated metal was stored in physiologically inactive tissues such as the foliar epidermis. However, an exception is Berkheya coddii, which has a distinctly different pattern of Ni distribution in leaves, with the highest concentration in the mesophyll. Such a distribution suggests that different physiological mechanisms are involved in the Ni transport, storage location and detoxification, compared to other hyperaccumulator species. Berkheya coddii is a plant with high potential for phytoremediation and phytomining due to its large biomass and potentially high Ni yield, that can reach 7.6% of Ni in dry mass of leaves. Senecio coronatus is the only known hyperaccumulator with two genotypes, hyperaccumulating and non-hyperaccumulating, growing on Ni-enriched/metalliferous soil. Detailed ultrastructural studies were undertaken to characterize specialized groups of cells in the root cortex of Ni-hyperaccumulating genotype, that are not known from any other hyperaccumulator. The occurrence of arbuscular mycorrhiza (AM) in Ni-hyperaccumulating plants was found for the first time in South African hyperaccumulator plants, and this type of symbiosis has been proved obligatory in all of them. There is a significant influence of mycorrhiza on the concentration and distribution of several elements. Three highly specialized herbivore insects feeding only on Ni hyperaccumulator plants were identified: Chrysolina clathrata (formerly Chrysolina pardalina), Epilachna nylanderi and Stenoscepa sp. The Ni-elimination strategies of these specialised insects have been established. Microbiological studies have revealed several genera of fungi and bacteria isolated from B. coddii leaves as well as presence of specialised, Ni-resistant yeasts in the C. clathrata gut. Understanding ecophysiological response to harsh environment broadens our knowledge and can have practical applications in cleaning polluted environments through phytomining/agromining. Finally, conservation aspects are also discussed and lines for future research are proposed.

RevDate: 2020-05-27

Kleinstein SE, Nelson KE, M Freire (2020)

Inflammatory Networks Linking Oral Microbiome with Systemic Health and Disease.

Journal of dental research [Epub ahead of print].

The dance between microbes and the immune system takes place in all biological systems, including the human body, but this interaction is especially complex in the primary gateway to the body: the oral cavity. Recent advances in technology have enabled deep sequencing and analysis of members and signals of these communities. In a healthy state, the oral microbiome is composed of commensals, and their genes and phenotypes may be selected by the immune system to survive in symbiosis. These highly regulated signals are modulated by a network of microbial and host metabolites. However, in a diseased state, host-microbial networks lead to dysbiosis and considerable burden to the host prior to systemic impact that extends beyond the oral compartment. Interestingly, we presented data demonstrating similarities between human and mice immune dysbiosis and discussed how this affects the host response to similar pathobionts. The host and microbial signatures of a number of disease states are currently being examined to identify potential correlations. How the oral microbiome interacts with inflammation and the immune system to cause disease remains an area of active research. In this review, we summarize recent advancements in understanding the role of oral microbiota in mediating inflammation and altering systemic health and disease. In line with these findings, it is possible that existing conditions may be resolved by targeting specific immune-microbial markers in a positive way.

RevDate: 2020-05-27

Guizzo MG, Neupane S, Kucera M, et al (2020)

Poor Unstable Midgut Microbiome of Hard Ticks Contrasts With Abundant and Stable Monospecific Microbiome in Ovaries.

Frontiers in cellular and infection microbiology, 10:211.

Culture-independent metagenomic methodologies have enabled detection and identification of microorganisms in various biological systems and often revealed complex and unknown microbiomes. In many organisms, the microbiome outnumbers the host cells and greatly affects the host biology and fitness. Ticks are hematophagous ectoparasites with a wide host range. They vector a number of human and animal pathogens and also directly cause major economic losses in livestock. Although several reports on a tick midgut microbiota show a diverse bacterial community, in most cases the size of the bacterial population has not been determined. In this study, the microbiome was quantified in the midgut and ovaries of the ticks Ixodes ricinus and Rhipicephalus microplus before, during, and after blood feeding. Although the size of bacterial community in the midgut fluctuated with blood feeding, it was overall extremely low in comparison to that of other hematophagous arthropods. In addition, the tick ovarian microbiome of both tick species exceeded the midgut 16S rDNA copy numbers by several orders of magnitude. This indicates that the ratio of a tick midgut/ovary microbiome represents an exception to the general biology of other metazoans. In addition to the very low abundance, the tick midgut diversity in I. ricinus was variable and that is in contrast to that found in the tick ovary. The ovary of I. ricinus had a very low bacterial diversity and a very high and stable bacterial abundance with the dominant endosymbiont, Midichloria sp. The elucidation of this aspect of tick biology highlights a unique tissue-specific microbial-invertebrate host interaction.

RevDate: 2020-05-27

Margarita V, Fiori PL, P Rappelli (2020)

Impact of Symbiosis Between Trichomonas vaginalis and Mycoplasma hominis on Vaginal Dysbiosis: A Mini Review.

Frontiers in cellular and infection microbiology, 10:179.

The protozoon Trichomonas vaginalis is responsible for trichomoniasis, a common sexually transmitted infection associated with an increased risk of HIV infection and adverse pregnancy outcomes. The protozoon has the surprising ability to establish a symbiotic relationship with other microorganisms. In fact, most T.vaginalis isolates intracellularly host the vaginal bacterium Mycoplasma hominis and can harbor up to four dsRNA viruses. Moreover, a novel Mycoplasma species named Ca. Mycoplasma girerdii has been recently described as associated with trichomonad cells. Trichomonas vaginalis colonizes the human vagina and its presence causes profound alterations of the resident microbiota, leading to dysbiosis. In healthy women, vaginal microbiota is characterized by the presence of a complex population of aerobic and anaerobic microorganisms living in a physiologically dynamic system dominated by bacteria of the genera Lactobacillus. The most common microbial vaginal imbalance is bacterial vaginosis, a polymicrobial disease associated with several adverse reproductive outcomes and increased risk of HIV infection. Here, we review the current knowledge regarding the interactions between both T.vaginalis and M.hominis and the vaginal microbiota, and we discuss the possibility of a cooperation between T.vaginalis and its symbionts in the development of vaginal dysbiosis.

RevDate: 2020-05-27

Freitas PP, Hampton JG, Rolston MP, et al (2020)

A Tale of Two Grass Species: Temperature Affects the Symbiosis of a Mutualistic Epichloë Endophyte in Both Tall Fescue and Perennial Ryegrass.

Frontiers in plant science, 11:530.

Many cool-season grasses form permanent, mutualistic symbioses with asexual Epichloë endophytes. These fungal symbionts often perform a protective role within the association as many strains produce secondary metabolites that deter certain mammalian and invertebrate herbivores. Although initially a serious issue for agriculture, due to mammalian toxins that manifested in major animal health issues, selected strains that provide abiotic stress protection to plants with minimal ill effects to livestock are now commercialized and routinely used to enhance pasture performance in many farming systems. These fungal endophytes and their grass hosts have coevolved over millions of years, and it is now generally accepted that most taxonomic groupings of Epichloë are confined to forming compatible associations (i.e., symptomless associations) with related grass genera within a tribe. The most desired compounds associated with Epichloë festucae var. lolii, an endophyte species associated with perennial ryegrass, are peramine and epoxy-janthitrems. No other major secondary metabolites with invertebrate bioactivity have been identified within this association. However, other agriculturally beneficial compounds, such as lolines, have been discovered in related endophyte species that form associations with fescue grasses. A rationale therefore existed to develop novel grass-endophyte associations between loline-producing endophytes originally isolated from tall fescue with elite cultivars of perennial ryegrass to achieve a wider spectrum of insect bioactivity. A suitable loline-producing endophyte strain of Epichloë sp. FaTG-3 was selected and inoculated into perennial ryegrass. We hypothesed that endophyte transmission frequency, endophyte mycelial biomass and endophyte-derived alkaloid production would differ between the original tall fescue host and the artificial association. Consistent with our hypothesis, our data strongly suggest that plant species significantly affected the plant-endophyte association. This effect became more apparent for transmission frequency and endophyte biomass as the plants matured. Overall, the viable endophyte infection frequency was greater in the tall fescue host than in perennial ryegrass, at all sampling dates. Additionally, temperature was found to be a significant factor affecting endophyte transmission frequency, endophyte mycelial biomass and alkaloid production. Implications for the development of novel grass-endophyte associations are discussed.

RevDate: 2020-05-27

Essock-Burns T, Bongrand C, Goldman WE, et al (2020)

Interactions of Symbiotic Partners Drive the Development of a Complex Biogeography in the Squid-Vibrio Symbiosis.

mBio, 11(3): pii:mBio.00853-20.

Microbes live in complex microniches within host tissues, but how symbiotic partners communicate to create such niches during development remains largely unexplored. Using confocal microscopy and symbiont genetics, we characterized the shaping of host microenvironments during light organ colonization of the squid Euprymna scolopes by the bacterium Vibrio fischeri During embryogenesis, three pairs of invaginations form sequentially on the organ's surface, producing pores that lead to interior compressed tubules at different stages of development. After hatching, these areas expand, allowing V. fischeri cells to enter and migrate ∼120 μm through three anatomically distinct regions before reaching blind-ended crypt spaces. A dynamic gatekeeper, or bottleneck, connects these crypts with the migration path. Once V. fischeri cells have entered the crypts, the bottlenecks narrow, and colonization by the symbiont population becomes spatially restricted. The actual timing of constriction and restriction varies with crypt maturity and with different V. fischeri strains. Subsequently, starting with the first dawn following colonization, the bottleneck controls a lifelong cycle of dawn-triggered expulsions of most of the symbionts into the environment and a subsequent regrowth in the crypts. Unlike other developmental phenotypes, bottleneck constriction is not induced by known microbe-associated molecular patterns (MAMPs) or by V. fischeri-produced bioluminescence, but it does require metabolically active symbionts. Further, while symbionts in the most mature crypts have a higher proportion of live cells and a greater likelihood of expulsion at dawn, they have a lower resistance to antibiotics. The overall dynamics of these distinct microenvironments reflect the complexity of the host-symbiont dialogue.IMPORTANCE The complexity, inaccessibility, and time scales of initial colonization of most animal microbiomes present challenges for the characterization of how the bacterial symbionts influence the form and function of tissues in the minutes to hours following the initial interaction of the partners. Here, we use the naturally occurring binary squid-vibrio association to explore this phenomenon. Imaging of the spatiotemporal landscape of this symbiosis during its onset provides a window into the impact of differences in both host-tissue maturation and symbiont strain phenotypes on the establishment of a dynamically stable symbiotic system. These data provide evidence that the symbionts shape the host-tissue landscape and that tissue maturation impacts the influence of strain-level differences on the daily rhythms of the symbiosis, the competitiveness for colonization, and antibiotic sensitivity.

RevDate: 2020-05-27

Teranishi T, Y Kobae (2020)

Investigation of Indigenous Arbuscular Mycorrhizal Performance Using a Lotus japonicus Mycorrhizal Mutant.

Plants (Basel, Switzerland), 9(5): pii:plants9050658.

Most plants are usually colonized with arbuscular mycorrhiza fungi (AMF) in the fields. AMF absorb mineral nutrients, especially phosphate, from the soil and transfer them to the host plants. Inoculation with exotic AMF is thought to be effective when indigenous AMF performance is low; however, there is no method for evaluating the performance of indigenous AMF. In this study, we developed a method to investigate the performance of indigenous AMF in promoting plant growth. As Lotus japonicus mutant (str) that are unable to form functional mycorrhizal roots were considered to be symbiosis negative for indigenous mycorrhizal performance, we examined the growth ratios of wild-type and str mycorrhizal mutant using 24 soils. Each soil had its own unique indigenous mycorrhizal performance, which was not directly related to the colonization level of indigenous AMF or soil phosphate level. The low indigenous mycorrhizal performance could not be compensated by the inoculation of exotic AMF. Importantly, indigenous mycorrhizal performance was never negative; however, the inoculation of exotic AMF into the same soil led to both positive and negative performances. These results suggest that indigenous mycorrhizal performance is affected by soil management history and is basically harmless to the plant.

RevDate: 2020-05-27
CmpDate: 2020-05-27

Chute JP, CM Termini (2019)

Mutualism in the Marrow.

Cell stem cell, 25(6):731-733.

Cross-talk between hematopoietic stem cells (HSCs) and the HSC niche is likely important in hematopoiesis but not well demonstrated. Now in Cell Stem Cell, Chen et al. (2019) describe how specialized endothelial cells regulate hematopoietic stem cell maintenance and how hematopoietic stem/progenitor cells facilitate vascular regeneration in return.

RevDate: 2020-05-27
CmpDate: 2020-05-27

Dou X, B Dong (2019)

Origins and Bioactivities of Natural Compounds Derived from Marine Ascidians and Their Symbionts.

Marine drugs, 17(12):.

Marine ascidians are becoming important drug sources that provide abundant secondary metabolites with novel structures and high bioactivities. As one of the most chemically prolific marine animals, more than 1200 inspirational natural products, such as alkaloids, peptides, and polyketides, with intricate and novel chemical structures have been identified from ascidians. Some of them have been successfully developed as lead compounds or highly efficient drugs. Although numerous compounds that exist in ascidians have been structurally and functionally identified, their origins are not clear. Interestingly, growing evidence has shown that these natural products not only come from ascidians, but they also originate from symbiotic microbes. This review classifies the identified natural products from ascidians and the associated symbionts. Then, we discuss the diversity of ascidian symbiotic microbe communities, which synthesize diverse natural products that are beneficial for the hosts. Identification of the complex interactions between the symbiont and the host is a useful approach to discovering ways that direct the biosynthesis of novel bioactive compounds with pharmaceutical potentials.

RevDate: 2020-05-27
CmpDate: 2020-05-27

Bublitz DC, Chadwick GL, Magyar JS, et al (2019)

Peptidoglycan Production by an Insect-Bacterial Mosaic.

Cell, 179(3):703-712.e7.

Peptidoglycan (PG) is a defining feature of bacteria, involved in cell division, shape, and integrity. We previously reported that several genes related to PG biosynthesis were horizontally transferred from bacteria to the nuclear genome of mealybugs. Mealybugs are notable for containing a nested bacteria-within-bacterium endosymbiotic structure in specialized insect cells, where one bacterium, Moranella, lives in the cytoplasm of another bacterium, Tremblaya. Here we show that horizontally transferred genes on the mealybug genome work together with genes retained on the Moranella genome to produce a PG layer exclusively at the Moranella cell periphery. Furthermore, we show that an insect protein encoded by a horizontally transferred gene of bacterial origin is transported into the Moranella cytoplasm. These results provide a striking parallel to the genetic and biochemical mosaicism found in organelles, and prove that multiple horizontally transferred genes can become integrated into a functional pathway distributed between animal and bacterial endosymbiont genomes.

RevDate: 2020-05-27
CmpDate: 2020-05-27

Boscaro V, Husnik F, Vannini C, et al (2019)

Symbionts of the ciliate Euplotes: diversity, patterns and potential as models for bacteria-eukaryote endosymbioses.

Proceedings. Biological sciences, 286(1907):20190693.

Endosymbioses between bacteria and eukaryotes are enormously important in ecology and evolution, and as such are intensely studied. Despite this, the range of investigated hosts is narrow in the context of the whole eukaryotic tree of life: most of the information pertains to animal hosts, while most of the diversity is found in unicellular protists. A prominent case study is the ciliate Euplotes, which has repeatedly taken up the bacterium Polynucleobacter from the environment, triggering its transformation into obligate endosymbiont. This multiple origin makes the relationship an excellent model to understand recent symbioses, but Euplotes may host bacteria other than Polynucleobacter, and a more detailed knowledge of these additional interactions is needed in order to correctly interpret the system. Here, we present the first systematic survey of Euplotes endosymbionts, adopting a classical as well as a metagenomic approach, and review the state of knowledge. The emerging picture is indeed quite complex, with some Euplotes harbouring rich, stable prokaryotic communities not unlike those of multicellular animals. We provide insights into the distribution, evolution and diversity of these symbionts (including the establishment of six novel bacterial taxa), and outline differences and similarities with the most well-understood group of eukaryotic hosts: insects.

RevDate: 2020-05-27
CmpDate: 2020-05-27

Liu H, Wu M, Liu J, et al (2020)

Tripartite Interactions Between Endophytic Fungi, Arbuscular Mycorrhizal Fungi, and Leymus chinensis.

Microbial ecology, 79(1):98-109.

Grasses often establish multiple simultaneous symbiotic associations with endophytic fungi and arbuscular mycorrhizal fungi (AMF). Many studies have examined pair-wise interactions between plants and endophytic fungi or between plants and AMF, overlooking the interplays among multiple endosymbionts and their combined impacts on hosts. Here, we examined both the way in which each symbiont affects the other symbionts and the tripartite interactions between leaf endophytic fungi, AMF, and Leymus chinensis. As for AMF, different species (Glomus etunicatum, GE; Glomus mosseae, GM; Glomus claroideum, GC; and Glomus intraradices, GI) and AMF richness (no AMF, single AMF taxa, double AMF mixtures, triple AMF mixtures, and all four together) were considered. Our results showed that significant interactions were observed between endophytes and AMF, with endophytes interacting antagonistically with GM but synergistically with GI. No definitive interactions were observed between the endophytes and GE or GC. Additionally, the concentration of endophytes in the leaf sheath was positively correlated with the concentration of AMF in the roots under low AMF richness. The shoot biomass of L. chinensis was positively related to both endophyte concentration and AMF concentration, with only endophytes contributing to shoot biomass more than AMF. Endophytes and AMF increased shoot growth by contributing to phosphorus uptake. The interactive effects of endophytes and AMF on host growth were affected by the identity of AMF species. The beneficial effect of the endophytes decreased in response to GM but increased in response to GI. However, no influences were observed with other GC and GE. In addition, endophyte presence can alter the response of host plants to AMF richness. When leaf endophytes were absent, shoot biomass increased with higher AMF richness, only the influence of AMF species identity outweighed that of AMF richness. However, when leaf endophytes were present, no significant association was observed between AMF richness and shoot biomass. AMF species identity rather than AMF richness promoted shoot growth. The results of this study demonstrate that the outcomes of interspecific symbiotic interactions are very complex and vary with partner identity such that the effects of simultaneous symbioses cannot be generalized and highlight the need for studies to evaluate fitness response of all three species, as the interactive effects may not be the same for each partner.

RevDate: 2020-05-26

Kokkoris V, Lekberg Y, Antunes PM, et al (2020)

Codependency between plant and arbuscular mycorrhizal fungal communities: what is the evidence?.

The New phytologist [Epub ahead of print].

That arbuscular mycorrhizal (AM) fungi covary with plant communities is clear, and many papers report non-random associations between symbiotic partners. However, these studies do not test the causal relationship, or "codependency", whereby the composition of one guild affects the composition of the other. Here we outline underlying requirements for codependency, compare important drivers for both plant and AM fungal communities, and assess how host preference-a pre-requisite for codependency-changes across spatiotemporal scales and taxonomic resolution for both plants and AM fungi. We find few examples in the literature designed to test for codependency and those that do have been conducted within plots or mesocosms. Also, while plants and AM fungi respond similarly to coarse environmental filters, most variation remains unexplained with host identity explaining less than 30% of the variation in AM fungal communities. These results combined question the likelihood of predictable co-occurrence, and therefore evolution of codependency, between plant and AM fungal taxa across locations. We argue that codependency is most likely to occur in homogeneous environments where specific plant - AM fungal pairings have functional consequences for the symbiosis. We end by outlining critical aspects to consider moving forward.

RevDate: 2020-05-26

Bellay S, Oda FH, Almeida-Neto M, et al (2020)

Host age predicts parasite occurrence, richness, and nested infracommunities in a pilot whale-helminth network.

Parasitology research pii:10.1007/s00436-020-06716-1 [Epub ahead of print].

Ecological data on marine mammal parasites represent an excellent opportunity to expand our understanding of host-parasite systems. In this study, we used a dataset of intestinal helminth parasites on 167 long-finned pilot whales Globicephala melas (Traill, 1809) from seven localities in the Faroe Islands to evaluate the extent to which the host's age and sex influence the occurrence, richness, and nested pattern of helminth parasites and the importance of individual hosts to the helminth community. We found positive effects of age on both the occurrence and richness of helminths. Older host individuals showed an ordered accumulation of parasites, as evidenced by the nested pattern in their composition. Males had a higher occurrence of parasites than females, but the richness of helminths did not differ between sexes. Our findings suggest that differences in host-parasite interactions in long-finned pilot whales result mainly from age-structured variations in biological and behavioral characteristics.

RevDate: 2020-05-26
CmpDate: 2020-05-26

Cheng S, Xian W, Fu Y, et al (2019)

Genomes of Subaerial Zygnematophyceae Provide Insights into Land Plant Evolution.

Cell, 179(5):1057-1067.e14.

The transition to a terrestrial environment, termed terrestrialization, is generally regarded as a pivotal event in the evolution and diversification of the land plant flora that changed the surface of our planet. Through phylogenomic studies, a group of streptophyte algae, the Zygnematophyceae, have recently been recognized as the likely sister group to land plants (embryophytes). Here, we report genome sequences and analyses of two early diverging Zygnematophyceae (Spirogloea muscicola gen. nov. and Mesotaenium endlicherianum) that share the same subaerial/terrestrial habitat with the earliest-diverging embryophytes, the bryophytes. We provide evidence that genes (i.e., GRAS and PYR/PYL/RCAR) that increase resistance to biotic and abiotic stresses in land plants, in particular desiccation, originated or expanded in the common ancestor of Zygnematophyceae and embryophytes, and were gained by horizontal gene transfer (HGT) from soil bacteria. These two Zygnematophyceae genomes represent a cornerstone for future studies to understand the underlying molecular mechanism and process of plant terrestrialization.

RevDate: 2020-05-26
CmpDate: 2020-05-26

Han LL, Wang Q, Shen JP, et al (2019)

Multiple factors drive the abundance and diversity of the diazotrophic community in typical farmland soils of China.

FEMS microbiology ecology, 95(8):.

Biological nitrogen fixation plays an important role in nitrogen cycling by transferring atmospheric N2 to plant-available N in the soil. However, the diazotrophic activity and distribution in different types of soils remain to be further explored. In this study, 152 upland soils were sampled to examine the diazotrophic abundance, nitrogenase activity, diversity and community composition by quantitative polymerase chain reaction, acetylene reduction assay and the MiSeq sequencing of nifH genes, respectively. The results showed that diazotrophic abundance and nitrogenase activity varied among the three soil types. The diazotrophic community was mainly dominated by Bradyrhizobium, Azospirillum, Myxobacter, Desulfovibrio and Methylobacterium. The symbiotic diazotroph Bradyrhizobium was widely distributed among soils, while the distribution of free-living diazotrophs showed large variation and was greatly affected by multiple factors. Crop type and soil properties directly affected the diazotrophic ɑ-diversity, while soil properties, climatic factors and spatial distance together influenced the diazotrophic community. Network structures were completely different among all three types of soils, with most complex interactions observed in the Red soil. These findings suggest that diazotrophs have various activities and distributions in the three soil types, which played different roles in nitrogen input in agricultural soil in China, being driven by multiple environmental factors.

RevDate: 2020-05-26
CmpDate: 2020-05-26

Gutleben J, Koehorst JJ, McPherson K, et al (2019)

Diversity of tryptophan halogenases in sponges of the genus Aplysina.

FEMS microbiology ecology, 95(8):.

Marine sponges are a prolific source of novel enzymes with promising biotechnological potential. Especially halogenases, which are key enzymes in the biosynthesis of brominated and chlorinated secondary metabolites, possess interesting properties towards the production of pharmaceuticals that are often halogenated. In this study we used a polymerase chain reaction (PCR)-based screening to simultaneously examine and compare the richness and diversity of putative tryptophan halogenase protein sequences and bacterial community structures of six Aplysina species from the Mediterranean and Caribbean seas. At the phylum level, bacterial community composition was similar amongst all investigated species and predominated by Actinobacteria, Chloroflexi, Cyanobacteria, Gemmatimonadetes, and Proteobacteria. We detected four phylogenetically diverse clades of putative tryptophan halogenase protein sequences, which were only distantly related to previously reported halogenases. The Mediterranean species Aplysina aerophoba harbored unique halogenase sequences, of which the most predominant was related to a sponge-associated Psychrobacter-derived sequence. In contrast, the Caribbean species shared numerous novel halogenase sequence variants and exhibited a highly similar bacterial community composition at the operational taxonomic unit (OTU) level. Correlations of relative abundances of halogenases with those of bacterial taxa suggest that prominent sponge symbiotic bacteria, including Chloroflexi and Actinobacteria, are putative producers of the detected enzymes and may thus contribute to the chemical defense of their host.

RevDate: 2020-05-26
CmpDate: 2020-05-26

Feng G, Zhang F, Banakar S, et al (2019)

Analysis of functional gene transcripts suggests active CO2 assimilation and CO oxidation by diverse bacteria in marine sponges.

FEMS microbiology ecology, 95(7):.

Bacteria are the dominant symbionts in sponges and are regarded as important contributors to ocean nutrient cycling; however, their roles in carbon utilization in sponge holobionts are seldom identified. Here, the in situ active bacteria and their CO2 assimilation and CO oxidation functions in sponges Theonella swinhoei, Plakortis simplex and Phakellia fusca were evaluated using the analysis of functional gene transcripts. Phylogenetically diverse bacteria belonging to 16 phyla were detected by 16S rRNA analysis. Particularly, some of the active bacteria appeared to be sponge-specific or even sponge species-specific. Transcribed autotrophic CO2 assimilation genes rbcL and rbcM, anaplerotic CO2 assimilation gene accC and aerobic CO oxidation gene coxL were uncovered and assigned to a wide variety of bacterial lineages. Some of these carbon metabolism genes showed specificity to sponge species or different transcriptional activity among the sponge species. This study uncovered the phylogenetic diversity of transcriptionally active bacteria especially with CO2 assimilation or CO oxidation functions, providing insights into the ecological functions of the sponge-symbiotic bacteria regarding carbon metabolism.

RevDate: 2020-05-25

Hojo F, Osaki T, Yonezawa H, et al (2020)

Acanthamoeba castellanii supports extracellular survival of Helicobacter pylori in co-culture.

Journal of infection and chemotherapy : official journal of the Japan Society of Chemotherapy pii:S1341-321X(20)30142-2 [Epub ahead of print].

This study aimed to demonstrate whether Helicobacter pylori is able to survive in co-culture with a protozoan, Acanthamoeba castellanii, in order to further investigate a possible aqueous environmental mode of transmission. Numbers of H. pylori in co-culture with A castellanii were assessed by colony forming unit (CFU) assay and cell morphology was observed by electron microscopy. Viable and intact H. pylori in co-culture were detected and the number of H. pylori in co-culture with A. castellanii was significantly higher than in bacterial single culture. It was also shown that co-culture of H. pylori with A. castellanii physically separated by a filter membrane negated this survival effect, suggesting that adherence of H. pylori to A. castellanii affects its survival. Scanning electron microscopy revealed helical forms of H. pylori in co-culture with A. castellanii, but not in single culture. These results imply that mutual interaction between H. pylori and A. castellanii in the environment is critical for survival of H. pylori. In addition, the H. pylori gene expression profile was found to differ between single and co-cultured cells using RNA-sequence analysis.

RevDate: 2020-05-23

diCenzo GC, Tesi M, Pfau T, et al (2020)

Genome-scale metabolic reconstruction of the symbiosis between a leguminous plant and a nitrogen-fixing bacterium.

Nature communications, 11(1):2574 pii:10.1038/s41467-020-16484-2.

The mutualistic association between leguminous plants and endosymbiotic rhizobial bacteria is a paradigmatic example of a symbiosis driven by metabolic exchanges. Here, we report the reconstruction and modelling of a genome-scale metabolic network of Medicago truncatula (plant) nodulated by Sinorhizobium meliloti (bacterium). The reconstructed nodule tissue contains five spatially distinct developmental zones and encompasses the metabolism of both the plant and the bacterium. Flux balance analysis (FBA) suggests that the metabolic costs associated with symbiotic nitrogen fixation are primarily related to supporting nitrogenase activity, and increasing N2-fixation efficiency is associated with diminishing returns in terms of plant growth. Our analyses support that differentiating bacteroids have access to sugars as major carbon sources, ammonium is the main nitrogen export product of N2-fixing bacteria, and N2 fixation depends on proton transfer from the plant cytoplasm to the bacteria through acidification of the peribacteroid space. We expect that our model, called 'Virtual Nodule Environment' (ViNE), will contribute to a better understanding of the functioning of legume nodules, and may guide experimental studies and engineering of symbiotic nitrogen fixation.

RevDate: 2020-05-23

Whitewoods CD (2020)

Evolution of CLE peptide signalling.

Seminars in cell & developmental biology pii:S1084-9521(19)30196-X [Epub ahead of print].

CLEs are small non-cell autonomous signalling peptides that regulate cell division rate and orientation in a variety of developmental contexts. Recent years have generated a huge amount of research on CLE function across land plants, characterising their role across the whole plant; they control stem cell division in the shoot, root and cambial meristems, balance developmental investment into symbiosis, regulate leaf development, pattern stomata and control axillary branching. They have even been co-opted by parasitic nematodes to mediate infection. This review synthesises these recent findings and embeds them in an evolutionary context, outlining the likely evolution of the CLE signalling pathway. I use this framework to infer common mechanistic themes and pose key future questions for the field.

RevDate: 2020-05-23

Manzano-Marín A (2020)

No evidence for Wolbachia as a nutritional co-obligate endosymbiont in the aphid Pentalonia nigronervosa.

Microbiome, 8(1):72 pii:10.1186/s40168-020-00865-2.

Obligate symbiotic associations are present in a wide variety of animals with a nutrient-restricted diet. Aphids (hemiptera: Aphididae) almost-universally host Buchnera aphidicola bacteria in specialised organs (called bacteriomes). These bacteria supply the aphid with essential nutrients lacking from their diet (i.e. essential amino acids and some B vitamins). Some aphid lineages, such as species from the Lacninae subfamily, have evolved co-obligate associations with secondary endosymbionts, deriving from a loss of biotin- and riboflavin-biosynthetic genes. In this study, I re-analyse previously published sequencing data from the banana aphid Pentalonia nigronervosa. I show that the metabolic inference results from De Clerck et al. (Microbiome 3:63, 2015) are incorrect and possibly arise from the use of inadequate methods. Additionally, I discuss how the seemingly biased interpretation of their antibiotic treatment analyses together with an incorrect genome-based metabolic inference resulted in the erroneous suggestion "that a co-obligatory symbiosis between B. aphidicola and Wolbachia occurs in the banana aphid".

RevDate: 2020-05-22

Bollati E, D'Angelo C, Alderdice R, et al (2020)

Optical Feedback Loop Involving Dinoflagellate Symbiont and Scleractinian Host Drives Colorful Coral Bleaching.

Current biology : CB pii:S0960-9822(20)30571-6 [Epub ahead of print].

Coral bleaching, caused by the loss of brownish-colored dinoflagellate photosymbionts from the host tissue of reef-building corals, is a major threat to reef survival. Occasionally, bleached corals become exceptionally colorful rather than white. These colors derive from photoprotective green fluorescent protein (GFP)-like pigments produced by the coral host. There is currently no consensus regarding what causes colorful bleaching events and what the consequences for the corals are. Here, we document that colorful bleaching events are a recurring phenomenon in reef regions around the globe. Our analysis of temperature conditions associated with colorful bleaching events suggests that corals develop extreme coloration within 2 to 3 weeks after exposure to mild or temporary heat stress. We demonstrate that the increase of light fluxes in symbiont-depleted tissue promoted by reflection of the incident light from the coral skeleton induces strong expression of the photoprotective coral host pigments. We describe an optical feedback loop involving both partners of the association, discussing that the mitigation of light stress offered by host pigments could facilitate recolonization of bleached tissue by symbionts. Our data indicate that colorful bleaching has the potential to identify local environmental factors, such as nutrient stress, that can exacerbate the impact of elevated temperatures on corals, to indicate the severity of heat stress experienced by corals and to gauge their post-stress recovery potential. VIDEO ABSTRACT.

RevDate: 2020-05-22

Larrainzar E, Villar I, Rubio MC, et al (2020)

Hemoglobins in the legume-rhizobium symbiosis.

The New phytologist [Epub ahead of print].

Legume nodules have two types of hemoglobins: symbiotic or leghemoglobins (Lbs) and nonsymbiotic or phytoglobins (Glbs). The latter are categorized into three phylogenetic classes differing in heme coordination and O2 affinity. This review is focused on the roles of Lbs and Glbs in the symbiosis of rhizobia with crop legumes and the model legumes for indeterminate (Medicago truncatula) and determinate (Lotus japonicus) nodulation. Only two hemoglobin functions are well established in nodules: Lbs deliver O2 to the bacteroids and act as O2 buffers, preventing nitrogenase inactivation; and Glb1-1 modulates nitric oxide concentration during symbiosis, from the early stage, avoiding the plant's defense response, to nodule senescence. Here, we critically examine early and recent results, update and correct the information on Lbs and Glbs with the latest genome versions, provide novel expression data, and identify targets for future research. Crucial unresolved questions include the expression of multiple Lbs in nodules, their presence in the nuclei and in uninfected nodule cells, and, intriguingly, their expression in nonsymbiotic tissues. RNA-sequencing data analysis show that Lbs are expressed as early as a few hours after inoculation and that their mRNAs are also detectable in roots and pods, which clearly suggests that these heme proteins play additional roles unrelated to nitrogen fixation. Likewise, issues awaiting investigation are the functions of other Glbs in nodules, the spatiotemporal expression profiles of Lbs and Glbs at the mRNA and protein levels, and the molecular mechanisms underlying their regulation during nodule development and in response to stress and hormones.

RevDate: 2020-05-22
CmpDate: 2020-05-22

El-Deeb O (2019)

Digest: Fitness costs of Spiroplasma infection in pea aphids.

Evolution; international journal of organic evolution, 73(7):1490-1491.

Endosymbionts sometimes help their hosts resist parasites, but does infection of pea aphids (Acyrthosiphon pisum) with different strains of the endosymbiont Spiroplasma confer fitness benefits that offset the costs? Mathé-Hubert et al. found that across four life-history traits, Spiroplasma infection induced negative effects on host fitness when compared to controls. Only two of 12 strains of Spiroplasma showed a marginal protective effect against host parasitism by Aphidius ervi, implying Spiroplasma infection is almost entirely detrimental to pea aphid host fitness.

RevDate: 2020-05-21

Ngugi DK, Ziegler M, Duarte CM, et al (2020)

Genomic Blueprint of Glycine Betaine Metabolism in Coral Metaorganisms and Their Contribution to Reef Nitrogen Budgets.

iScience, 23(5):101120 pii:S2589-0042(20)30305-9 [Epub ahead of print].

The osmolyte glycine betaine (GB) ranks among the few widespread biomolecules in all three domains of life. In corals, tissue concentrations of GB are substantially higher than in the ambient seawater. However, the synthetic routes remain unresolved, questioning whether intracellular GB originates from de novo synthesis or heterotrophic input. Here we show that the genomic blueprint of coral metaorganisms encode the biosynthetic and degradation machinery for GB. Member organisms also adopted the prokaryotic high-affinity carrier-mediated uptake of exogenous GB, rendering coral reefs potential sinks of marine dissolved GB. The machinery metabolizing GB is highly expressed in the coral model Aiptasia and its microalgal symbionts, signifying GB's role in the cnidarian-dinoflagellate symbiosis. We estimate that corals store between 106-109 grams of GB globally, representing about 16% of their nitrogen biomass. Our findings provide a framework for further mechanistic studies addressing GB's role in coral biology and reef ecosystem nitrogen cycling.

RevDate: 2020-05-21

Ke T, Santamaría A, Tinkov AA, et al (2020)

Generating Bacterial Foods in Toxicology Studies with Caenorhabditis elegans.

Current protocols in toxicology, 84(1):e94.

Caenorhabditis elegans is a free-living animal that is used as a powerful experimental model in biological sciences. The natural habitat of the animal are areas rich in material from rotting plants or fruits being decomposed by a growing number of microorganisms. The ecology of the natural habitat of C. elegans is a complex interactive network involving many species, including numerous types of bacteria, viruses, fungi, slugs, snails, and isopods, among which bacteria play multifaceted roles in the natural history of C. elegans. Under laboratory conditions, C. elegans is routinely cultured in a petri dish filled with solidified agar and seeded with Escherichia coli strain OP50, the latter offering an alternative model to study the interaction between bacteria and host. Because of the clear advantages of generating specific bacterial foods for mechanistic studies in C. elegans, it is important to develop a robust protocol to generate high-quality bacterial foods commensurate with experimental requirements. Based on previous work by us and others, herein we present a protocol on how to generate these optimal bacterial food-based research tools. © 2020 by John Wiley & Sons, Inc. Basic Protocol 1: Preparing concentrated E. coli OP50 Basic Protocol 2: Titrating bacteria concentration Basic Protocol 3: Generating dead bacterial food by heating Basic Protocol 4: Generating dead bacterial food by antibiotics Basic Protocol 5: Feeding C. elegans with bacterial foods in liquid.

RevDate: 2020-05-21

Weemstra M, Peay KG, Davies SJ, et al (2020)

Lithological constraints on resource economies shape the mycorrhizal composition of a Bornean rain forest.

The New phytologist [Epub ahead of print].

-Arbuscular mycorrhizal fungi (AMF) and ectomycorrhizal fungi (EMF) produce contrasting plant-soil feedbacks, but how these feedbacks are constrained by lithology is poorly understood. -We investigated the hypothesis that lithological drivers of soil fertility filter plant resource economic strategies in ways that influence the relative fitness of trees with AMF or EMF symbioses in a Bornean rain forest containing species with both mycorrhizal strategies. -Using forest inventory data on 1245 tree species, we found that although AMF-hosting trees had greater relative dominance on all soil types, with declining lithological soil fertility, EMF-hosting trees became more dominant. Data on 13 leaf traits and wood density for a total of 150 species showed that variation was almost always associated with soil type, whereas for six leaf traits (structural properties; carbon, nitrogen, phosphorus ratios; nitrogen isotopes), variation was also associated with mycorrhizal strategy. EMF-hosting species had slower leaf economics than AMF-hosts, demonstrating the central role of mycorrhizal symbiosis in plant resource economies. -At the global scale, climate has been shown to shape forest mycorrhizal composition, but here we show that, in communities, it depends on soil lithology, suggesting scale-dependent abiotic factors influence feedbacks underlying the relative fitness of different mycorrhizal strategies.

RevDate: 2020-05-21

Borghi M, Puccetti M, Pariano M, et al (2020)

Tryptophan as a Central Hub for Host/Microbial Symbiosis.

International journal of tryptophan research : IJTR, 13:1178646920919755 pii:10.1177_1178646920919755.

Amino acid catabolism occurs during inflammation and regulates innate and adaptive immunity. The role of commensal bacteria in amino acid catabolism and the production of metabolites able to regulate the development and function of the innate immune system is increasingly being recognized. Therefore, commensal bacteria are key players in the maintenance of immune homeostasis. However, the intestinal microbiota also contributes to susceptibility and response to infectious diseases. This is self-evident for fungal infections known to occur as a consequence of weakened immune system and broad-spectrum antibiotic use or abuse. Thus, diseases caused by opportunistic fungi can no longer be viewed as dependent only on a weakened host but also on a disrupted microbiota. Based on these premises, the present review focuses on the role of amino acid metabolic pathways in the dialogue between the mammalian host and its microbiota and the potential implications in fungal commensalism and infectivity.

RevDate: 2020-05-21
CmpDate: 2020-05-21

Smith CC, Weber JN, Mikheyev AS, et al (2019)

Landscape genomics of an obligate mutualism: Concordant and discordant population structures between the leafcutter ant Atta texana and its two main fungal symbiont types.

Molecular ecology, 28(11):2831-2845.

To explore landscape genomics at the range limit of an obligate mutualism, we use genotyping-by-sequencing (ddRADseq) to quantify population structure and the effect of host-symbiont interactions between the northernmost fungus-farming leafcutter ant Atta texana and its two main types of cultivated fungus. Genome-wide differentiation between ants associated with either of the two fungal types is of the same order of magnitude as differentiation associated with temperature and precipitation across the ant's entire range, suggesting that specific ant-fungus genome-genome combinations may have been favoured by selection. For the ant hosts, we found a broad cline of genetic structure across the range, and a reduction of genetic diversity along the axis of range expansion towards the range margin. This population-genetic structure was concordant between the ants and one cultivar type (M-fungi, concordant clines) but discordant for the other cultivar type (T-fungi). Discordance in population-genetic structures between ant hosts and a fungal symbiont is surprising because the ant farmers codisperse with their vertically transmitted fungal symbionts. Discordance implies that (a) the fungi disperse also through between-nest horizontal transfer or other unknown mechanisms, and (b) genetic drift and gene flow can differ in magnitude between each partner and between different ant-fungus combinations. Together, these findings imply that variation in the strength of drift and gene flow experienced by each mutualistic partner affects adaptation to environmental stress at the range margin, and genome-genome interactions between host and symbiont influence adaptive genetic differentiation of the host during range evolution in this obligate mutualism.

RevDate: 2020-05-21
CmpDate: 2020-05-21

Stewart D, Romo JA, Lamendella R, et al (2019)

The role of fungi in C. difficile infection: An underappreciated transkingdom interaction.

Fungal genetics and biology : FG & B, 129:1-6.

Novel culture independent technologies have further elucidated the composition of the human mycobiome, though the role of fungi in human health and disease remains largely unknown. Recent studies have suggested conflicting roles for fungi in the gastrointestinal tract, underscoring the complexity of the interactions between the mycobiome, its bacterial counterpart, and the host. One key example is the observation that fungal taxa are overrepresented in patients with Clostridioides difficile infection (CDI), suggesting a role for fungi in this disease. Recent studies in murine models have demonstrated the ability of the commensal fungus Candida albicans to alter the course of CDI, supporting the notion that fungi play a role in this infection. This review summarizes current data on fungi and CDI, and shows that views of the dysbiotic state that is central to the pathogenesis of CDI are incomplete without consideration of the mycobiome.

RevDate: 2020-05-20

Zheng D, Liwinski T, E Elinav (2020)

Interaction between microbiota and immunity in health and disease.

Cell research pii:10.1038/s41422-020-0332-7 [Epub ahead of print].

The interplay between the commensal microbiota and the mammalian immune system development and function includes multifold interactions in homeostasis and disease. The microbiome plays critical roles in the training and development of major components of the host's innate and adaptive immune system, while the immune system orchestrates the maintenance of key features of host-microbe symbiosis. In a genetically susceptible host, imbalances in microbiota-immunity interactions under defined environmental contexts are believed to contribute to the pathogenesis of a multitude of immune-mediated disorders. Here, we review features of microbiome-immunity crosstalk and their roles in health and disease, while providing examples of molecular mechanisms orchestrating these interactions in the intestine and extra-intestinal organs. We highlight aspects of the current knowledge, challenges and limitations in achieving causal understanding of host immune-microbiome interactions, as well as their impact on immune-mediated diseases, and discuss how these insights may translate towards future development of microbiome-targeted therapeutic interventions.

RevDate: 2020-05-20

Wollein Waldetoft K, Råberg L, R Lood (2020)

Proliferation and benevolence-A framework for dissecting the mechanisms of microbial virulence and health promotion.

Evolutionary applications, 13(5):879-888 pii:EVA12952.

Key topics in the study of host-microbe interactions-such as the prevention of drug resistance and the exploitation of beneficial effects of bacteria-would benefit from concerted efforts with both mechanistic and evolutionary approaches. But due to differences in intellectual traditions, insights gained in one field rarely benefit the other. Here, we develop a conceptual and analytical framework for the integrated study of host-microbe interactions. This framework partitions the health effects of microbes and the effector molecules they produce into components with different evolutionary implications. It thereby facilitates the prediction of evolutionary responses to inhibition and exploitation of specific molecular mechanisms.

RevDate: 2020-05-20

Newkirk CR, Frazer TK, Martindale MQ, et al (2020)

Adaptation to Bleaching: Are Thermotolerant Symbiodiniaceae Strains More Successful Than Other Strains Under Elevated Temperatures in a Model Symbiotic Cnidarian?.

Frontiers in microbiology, 11:822.

The ability of some symbiotic cnidarians to resist and better withstand stress factors that cause bleaching is a trait that is receiving increased attention. The adaptive bleaching hypothesis postulates that cnidarians that can form a stable symbiosis with thermotolerant Symbiodiniaceae strains may cope better with increasing seawater temperatures. We used polyps of the scyphozoan, Cassiopea xamachana, as a model system to test symbiosis success under heat stress. We sought to determine: (1) if aposymbiotic C. xamachana polyps could establish and maintain a symbiosis with both native and non-native strains of Symbiodiniaceae that all exhibit different tolerances to heat, (2) whether polyps with these newly acquired Symbiodiniaceae strains would strobilate (produce ephyra), and (3) if thermally tolerant Symbiodiniaceae strains that established and maintained a symbiosis exhibited greater success in response to heat stress (even if they are not naturally occurring in Cassiopea). Following recolonization of aposymbiotic C. xamachana polyps with different strains, we found that: (1) strains Smic, Stri, Slin, and Spil all established a stable symbiosis that promoted strobilation and (2) strains Bmin1 and Bmin2 did not establish a stable symbiosis and strobilation did not occur. Strains Smic, Stri, Slin, and Spil were used in a subsequent bleaching experiment; each of the strains was introduced to a subset of aposymbiotic polyps and once polyp tissues were saturated with symbionts they were subjected to elevated temperatures - 32°C and 34°C - for 2 weeks. Our findings indicate that, in general, pairings of polyps with Symbiodiniaceae strains that are native to Cassiopea (Stri and Smic) performed better than a non-native strain (Slin) even though this strain has a high thermotolerance. This suggests a degree of partner specificity that may limit the adaptive potential of certain cnidarians to increased ocean warming. We also observed that the free-living, non-native thermotolerant strain Spil was relatively successful in resisting bleaching during experimental trials. This suggests that free-living Symbiodiniaceae may provide a supply of potentially "new" thermotolerant strains to cnidarians following a bleaching event.

RevDate: 2020-05-20

Lemmer KC, Alberge F, Myers KS, et al (2020)

The NtrYX Two-Component System Regulates the Bacterial Cell Envelope.

mBio, 11(3): pii:mBio.00957-20.

Activity of the NtrYX two-component system has been associated with important processes in diverse bacteria, ranging from symbiosis to nitrogen and energy metabolism. In the facultative alphaproteobacterium Rhodobacter sphaeroides, loss of the two-component system NtrYX results in increased lipid production and sensitivity to some known cell envelope-active compounds. In this study, we show that NtrYX directly controls multiple properties of the cell envelope. We find that the response regulator NtrX binds upstream of cell envelope genes, including those involved in peptidoglycan biosynthesis and modification and in cell division. We show that loss of NtrYX impacts the cellular levels of peptidoglycan precursors and lipopolysaccharide and alters cell envelope structure, increasing cell length and the thickness of the periplasm. Cell envelope function is also disrupted in the absence of NtrYX, resulting in increased outer membrane permeability. Based on the properties of R. sphaeroides cells lacking NtrYX and the target genes under direct control of this two-component system, we propose that NtrYX plays a previously undescribed, and potentially conserved, role in the assembly, structure, and function of the cell envelope in a variety of bacteria.IMPORTANCE The bacterial cell envelope provides many important functions. It protects cells from harsh environments, serves as a selective permeability barrier, houses bioenergetic functions, defines sensitivity to antibacterial agents, and plays a crucial role in biofilm formation, symbiosis, and virulence. Despite the important roles of this cellular compartment, we lack a detailed understanding of the biosynthesis and remodeling of the cell envelope. Here, we report that the R. sphaeroides two-component signaling system NtrYX is a previously undescribed regulator of cell envelope processes, providing evidence that it is directly involved in controlling transcription of genes involved in cell envelope assembly, structure, and function in this and possibly other bacteria. Thus, our data report on a newly discovered process used by bacteria to assemble and remodel the cell envelope.

RevDate: 2020-05-20

Swain TD, Lax S, Backman V, et al (2020)

Uncovering the role of Symbiodiniaceae assemblage composition and abundance in coral bleaching response by minimizing sampling and evolutionary biases.

BMC microbiology, 20(1):124 pii:10.1186/s12866-020-01765-z.

BACKGROUND: Biodiversity and productivity of coral-reef ecosystems depend upon reef-building corals and their associations with endosymbiotic Symbiodiniaceae, which offer diverse functional capabilities to their hosts. The number of unique symbiotic partners (richness) and relative abundances (evenness) have been hypothesized to affect host response to climate change induced thermal stress. Symbiodiniaceae assemblages with many unique phylotypes may provide greater physiological flexibility or form less stable symbioses; assemblages with low abundance phylotypes may allow corals to retain thermotolerant symbionts or represent associations with less-suitable symbionts.

RESULTS: Here we demonstrate that true richness of Symbiodiniaceae phylotype assemblages is generally not discoverable from direct enumeration of unique phylotypes in association records and that cross host-species comparisons are biased by sampling and evolutionary patterns among species. These biases can be minimized through rarefaction of richness (rarefied-richness) and evenness (Probability of Interspecific Encounter, PIE), and analyses that account for phylogenetic patterns. These standardized metrics were calculated for individual Symbiodiniaceae assemblages composed of 377 unique ITS2 phylotypes associated with 123 coral species. Rarefied-richness minimized correlations with sampling effort, while maintaining important underlying characteristics across host bathymetry and geography. Phylogenetic comparative methods reveal significant increases in coral bleaching and mortality associated with increasing Symbiodiniaceae assemblage richness and evenness at the level of host species.

CONCLUSIONS: These results indicate that the potential flexibility afforded by assemblages characterized by many phylotypes present at similar relative abundances does not result in decreased bleaching risk and point to the need to characterize the overall functional and genetic diversity of Symbiodiniaceae assemblages to quantify their effect on host fitness under climate change.

RevDate: 2020-05-20

Miyake K, Kito K, Kotemori A, et al (2020)

Association between Pet Ownership and Obesity: A Systematic Review and Meta-Analysis.

International journal of environmental research and public health, 17(10): pii:ijerph17103498.

Obesity is a major risk factor for lifestyle-related diseases, including cardiovascular disease, type 2 diabetes, and hypertension. Several studies have investigated the association between pet ownership and obesity, but the findings have been inconsistent. This systematic literature review and meta-analysis assessed the association between pet ownership and obesity. Using PubMed and Scopus, we overviewed the literature published until December 2019 and selected pertinent data for meta-analysis. Two independent reviewers extracted the data. Pooled relative risks (RRs) with 95% confidence intervals (CIs) for obesity were calculated using the random-effects model with inverse-variance weighting. The 21 included articles were cross-sectional studies. Five publications (nine analyses) that reported adjusted RRs for BMI ≥ 25 were included in the meta-analysis. No significant association existed between pet ownership and obesity (pooled RR = 1.038; 95% CI, 0.922-1.167; I2 = 51.8%). After stratification by age group (children vs. adults), no significant association was detected (pooled RR = 0.844; 95% CI, 0.604-1.179; I2 = 64.1% vs. pooled RR = 1.099; 95% CI, 0.997-1.212; I2 = 25.2%). Similarly, no significant association was observed between dog ownership and obesity, indicating no association between pet ownership and obesity. However, no infer causation can be reported because all studies included in this meta-analysis were cross-sectional. Therefore, further prospective studies are needed.

RevDate: 2020-05-20

Liu Z, J Shu (2020)

Characterization of Microstructure, Precipitations and Microsegregation in Laser Additive Manufactured Nickel-Based Single-Crystal Superalloy.

Materials (Basel, Switzerland), 13(10): pii:ma13102300.

In this study, the microstructure, precipitations, and microsegregation in the laser additive manufactured thin-wall structure of a single-crystal superalloy are synthetically characterized. The influence of a subsequent heat treatment on the microstructure and precipitations is discussed. The results show that under the given processing conditions, the single-crystal microstructure is regenerated perfectly with small misorientation angles in the thin-wall structure. The crystal morphology shows obvious diversity and instability with the incremental height of thin-wall structure. With the increase of manufacturing height, both the primary and secondary dendritic arm spacings of epitaxial columnar dendrites first increase rapidly and then reach a dynamic balanced state. The distribution of precipitations and pores keeps symbiosis in the interdendritic region and shows periodic band characteristic with high density in the band region and low density in the inner region of plate layers. The microsegregation of element atoms in the microstructure shows a three-dimensional network distribution. The concentration of element atoms keeps good consistency with high value in the three-dimensional network and nearly standard value in the outside region. The subsequent heat treatment process contributes to the occupation of as-processed pores by the expanded mature precipitations with good blocky shape. Further optimization of the heat treatment process for improving the lattice coherency of precipitated γ' phase and γ matrix in the laser additive manufactured single-crystal superalloy is needed and valuable.

RevDate: 2020-05-20

Sariola S, SF Gilbert (2020)

Toward a Symbiotic Perspective on Public Health: Recognizing the Ambivalence of Microbes in the Anthropocene.

Microorganisms, 8(5): pii:microorganisms8050746.

Microbes evolve in complex environments that are often fashioned, in part, by human desires. In a global perspective, public health has played major roles in structuring how microbes are perceived, cultivated, and destroyed. The germ theory of disease cast microbes as enemies of the body and the body politic. Antibiotics have altered microbial development by providing stringent natural selection on bacterial species, and this has led to the formation of antibiotic-resistant bacterial strains. Public health perspectives such as "Precision Public Health" and "One Health" have recently been proposed to further manage microbial populations. However, neither of these take into account the symbiotic relationships that exist between bacterial species and between bacteria, viruses, and their eukaryotic hosts. We propose a perspective on public health that recognizes microbial evolution through symbiotic associations (the hologenome theory) and through lateral gene transfer. This perspective has the advantage of including both the pathogenic and beneficial interactions of humans with bacteria, as well as combining the outlook of the "One Health" model with the genomic methodologies utilized in the "Precision Public Health" model. In the Anthropocene, the conditions for microbial evolution have been altered by human interventions, and public health initiatives must recognize both the beneficial (indeed, necessary) interactions of microbes with their hosts as well as their pathogenic interactions.

RevDate: 2020-05-19

Stairs CW, TJG Ettema (2020)

The Archaeal Roots of the Eukaryotic Dynamic Actin Cytoskeleton.

Current biology : CB, 30(10):R521-R526.

It is generally well accepted that eukaryotes evolved from the symbiosis of an archaeal host cell and an alphaproteobacterium, a union that ultimately gave rise to the complex, eukaryotic cells we see today. However, the catalyst of this merger, the exact nature of the cellular biology of either partner, or how this event spawned the vast majority of complex life on Earth remains enigmatic. In recent years, the discovery of the Asgard archaea, the closest known prokaryotic relatives of eukaryotes, has been monumental for addressing these unanswered questions. These prokaryotes seem to encode an unprecedented number of genes related to features typically descriptive of eukaryotes, including intracellular trafficking, vesicular transport and a dynamic actin-based cytoskeleton. Collectively, these features imply that the Asgard archaea have the potential for cellular complexity previously thought to be unique to eukaryotes. Here, we review the most recent advances in our understanding of the archaeal cytoskeleton and its implications for determining the origin of eukaryotic cellular complexity.

RevDate: 2020-05-19

Merckx VSFT, SIF Gomes (2020)

Symbiosis: Herbivory Alters Mycorrhizal Nutrient Exchange.

Current biology : CB, 30(10):R437-R439.

A new study shows that a plant gives less carbon to its root-associated mycorrhizal fungus when targeted by herbivores, but the fungus doesn't retaliate.

RevDate: 2020-05-19

Buerger P, Alvarez-Roa C, Coppin CW, et al (2020)

Heat-evolved microalgal symbionts increase coral bleaching tolerance.

Science advances, 6(20):eaba2498 pii:aba2498.

Coral reefs worldwide are suffering mass mortalities from marine heat waves. With the aim of enhancing coral bleaching tolerance, we evolved 10 clonal strains of a common coral microalgal endosymbiont at elevated temperatures (31°C) for 4 years in the laboratory. All 10 heat-evolved strains had expanded their thermal tolerance in vitro following laboratory evolution. After reintroduction into coral host larvae, 3 of the 10 heat-evolved endosymbionts also increased the holobionts' bleaching tolerance. Although lower levels of secreted reactive oxygen species (ROS) accompanied thermal tolerance of the heat-evolved algae, reduced ROS secretion alone did not predict thermal tolerance in symbiosis. The more tolerant symbiosis exhibited additional higher constitutive expression of algal carbon fixation genes and coral heat tolerance genes. These findings demonstrate that coral stock with enhanced climate resilience can be developed through ex hospite laboratory evolution of their microalgal endosymbionts.

RevDate: 2020-05-19

Missbah El Idrissi M, Lamin H, Bouhnik O, et al (2020)

Characterization of Pisum sativum and Vicia faba microsymbionts in Morocco and definition of symbiovar viciae in Rhizobium acidisoli.

Systematic and applied microbiology pii:S0723-2020(20)30035-7 [Epub ahead of print].

In this work, we analyzed the diversity of seventy-six bacteria isolated from Pea and faba bean nodules in two regions of Morocco. The molecular diversity was realized using the analysis of the sequences of 16S rRNA and six housekeeping genes (recA, glnII, atpD, dnaK, rpoB and gyrB) and two symbiotic genes (nodA and nodC). The phylogeny of the 16S rRNA gene sequences revealed that all strains belong to the genus Rhizobium, being related to the type strains of R. leguminosarum, R. laguerreae, R. indigoferae, R. anhuiense and R. acidisoli. The housekeeping genes phylogenies showed that some strains formed a subclade distinct from the rhizobial species that usually nodulate Vicia faba and Pisum sativum which are closely related to R. acidisoli FH23 with sequence similarity of 98.3%. Analysis of the PGPR activities of the different isolates showed that the strains related to R. laguerreae were able to solubilize phosphates and to produce siderophores and auxin phytohormone. However, R. acidisoli strain F40D2 was unable to solubilize phosphates although they produce siderophores and IAA. The phylogenetic analysis of the nodA and nodC sequences showed that all isolated strains were closely related with the strains of symbiovar viciae. The nodulation tests confirmed the ability to nodulate V. faba and P. sativum but not Cicer arietinum or Phaseolus vulgaris. Hence, in Morocco P. sativum is nodulated by R. laguerreae; whereas V. faba is nodulated by R. laguerreae and the symbiovar viciae of R. acidisoli which has been not previously described in this species.

RevDate: 2020-05-19
CmpDate: 2020-05-19

Imhof S, Feller B, A Heser (2020)

Morpho-anatomical differences among mycoheterotrophic Afrothismia spp. (Thismiaceae) indicate an evolutionary progression towards improved mycorrhizal benefit.

Mycorrhiza, 30(2-3):397-405.

Achlorophyllous, mycoheterotrophic plants depend on their mycorrhizal fungi for 100% of their carbon supply. Hence, there is strong evolutionary pressure towards a well-organized functioning of the association from the plant's perspective. Members of the mycoheterotrophic genus Afrothismia have evolved elaborate fungal colonization patterns allowing a sustained benefit from external fungal penetration events. On the basis of anatomical details of the root-shoot systems of A. korupensis and A. hydra, we elucidate an evolutionary progression between the comparatively simple mycorrhizal pattern in A. gesnerioides and the so far most complex mycorrhiza in A. saingei. We detected two major advancements: (1) two species, A. korupensis and A. saingei, use the fungus itself as energy storage, replacing starch depositions used by A. gesnerioides and A. hydra, and (2) the morphological complexity of hyphal forms in plant tissue compartments increases from A. gesnerioides to A. saingei. We discuss the omitting of starch metabolism as well as the morpho-anatomical differences as an evolutionary fine-tuning of the compartmented mycorrhizal organization in Afrothismia. Our results support the idea of a taxonomic distinction between Afrothismia and other Thismiaceae.

RevDate: 2020-05-19
CmpDate: 2020-05-19

de Novais CB, Sbrana C, da Conceição Jesus E, et al (2020)

Mycorrhizal networks facilitate the colonization of legume roots by a symbiotic nitrogen-fixing bacterium.

Mycorrhiza, 30(2-3):389-396.

Arbuscular mycorrhizal fungi (AMF) absorb and translocate nutrients from soil to their host plants by means of a wide network of extraradical mycelium (ERM). Here, we assessed whether nitrogen-fixing rhizobia can be transferred to the host legume Glycine max by ERM produced by Glomus formosanum isolate CNPAB020 colonizing the grass Urochloa decumbens. An H-bridge experimental system was developed to evaluate the migration of ERM and of the GFP-tagged Bradyrhizobium diazoefficiens USDA 110 strain across an air gap compartment. Mycorrhizal colonization, nodule formation in legumes, and occurrence of the GFP-tagged strain in root nodules were assessed by optical and confocal laser scanning microscopy. In the presence of non-mycorrhizal U. decumbens, legume roots were neither AMF-colonized nor nodulated. In contrast, G. formosanum ERM crossing the discontinuous compartment connected mycorrhizal U. decumbens and G. max roots, which showed 30-42% mycorrhizal colonization and 7-11 nodules per plant. Fluorescent B. diazoefficiens cells were detected in 94% of G. max root nodules. Our findings reveal that, besides its main activity in nutrient transfer, ERM produced by AMF may facilitate bacterial translocation and the simultaneous associations of plants with beneficial fungi and bacteria, representing an important structure, functional to the establishment of symbiotic relationships.

RevDate: 2020-05-19
CmpDate: 2020-05-19

Gao Y, Zhao Z, Li J, et al (2020)

Do fungal associates of co-occurring orchids promote seed germination of the widespread orchid species Gymnadenia conopsea?.

Mycorrhiza, 30(2-3):221-228.

Interactions with mycorrhizal fungi have been increasingly recognized as one of the most important ecological factors determining the distribution and local abundance of orchids. While some orchid species may interact with a variety of fungal associates, others are more specific in their choice of mycorrhizal partners. Moreover, orchids that co-occur at a given site, often associate with different partners, possibly to avoid competition and to allow stable coexistence. However, whether differences in mycorrhizal partners directly affect seed germination and subsequent protocorm formation remains largely unknown. In this research, we used in vitro germination experiments to investigate to what extent seed germination and protocorm formation of Gymnadenia conopsea was affected by the origin and identity of fungal associates. Fungi were isolated from G. conopsea and three other co-occurring orchid species (Dactylorhiza viridis (Coeloglossum viride), Herminium monorchis, and Platanthera chlorantha). In total, eight fungal associates, belonging to Tulasnellaceae, Ceratobasidiaceae, and Serendipitaceae, were successfully isolated and cultured. While all eight fungal strains were able to promote early germination of G. conopsea seeds, only fungal strain GS2, a member of the Ceratobasidiaceae isolated from G. conopsea itself, was able to promote protocorm formation and subsequent growth to a seedling. Two other fungal strains isolated from G. conopsea only supported seed germination until the protocorm formation stage. The other five fungal strains isolated from the co-occurring orchid species did not support seed germination beyond the protocorm stage. We conclude that, although G. conopsea is considered a mycorrhizal generalist that associates with a wide range of fungi during its adult life, it requires specific fungi to promote protocorm formation and growth to a seedling.

RevDate: 2020-05-20
CmpDate: 2020-05-20

Romero-Gutiérrez KJ, Dourado MN, Garrido LM, et al (2020)

Phenotypic traits of Burkholderia spp. associated with ecological adaptation and plant-host interaction.

Microbiological research, 236:126451.

Burkholderia species have different lifestyles establishing mutualist or pathogenic associations with plants and animals. Changes in the ecological behavior of these bacteria may depend on genetic variations in response to niche adaptation. Here, we studied 15 Burkholderia strains isolated from different environments with respect to genetic and phenotypic traits. By Multilocus Sequence Analysis (MLSA) these isolates fell into 6 distinct groups. MLSA clusters did not correlate with strain antibiotic sensitivity, but with the bacterial ability to produce antimicrobial compounds and control orchid necrosis. Further, the B. seminalis strain TC3.4.2R3, a mutualistic bacterium, was inoculated into orchid plants and the interaction with the host was evaluated by analyzing the plant response and the bacterial oxidative stress response in planta. TC3.4.2R3 responded to plant colonization by increasing its own growth rate and by differential gene regulation upon oxidative stress caused by the plant, while reducing the plant's membrane lipid peroxidation. The bacterial responses to oxidative stress were recapitulated by bacterial exposure to the herbicide paraquat. We suggest that the ability of Burkholderia species to successfully establish in the rhizosphere correlates with genetic variation, whereas traits associated with antibiotic resistance are more likely to be categorized as strain specific.

RevDate: 2020-05-19
CmpDate: 2020-05-19

Radkov AD, S Chou (2019)

An Affair to Remember: How an Endosymbiont Partners with Its Host to Build a Cell Envelope.

Cell, 179(3):584-586.

Studying endosymbionts gives us insight into early cellular mechanisms that led to the emergence of eukaryotic organelles. In this issue of Cell, Bublitz et al. (2019) report on how a nested bacterial endosymbiont of mealybugs builds its cell wall peptidoglycan through a biosynthetic pathway that is dependent on transported host enzymes.

RevDate: 2020-05-20
CmpDate: 2020-05-20

Bagheri Z, Talebi AA, Asgari S, et al (2019)

Wolbachia induce cytoplasmic incompatibility and affect mate preference in Habrobracon hebetor to increase the chance of its transmission to the next generation.

Journal of invertebrate pathology, 163:1-7.

Wolbachia are common intracellular bacteria that are generally found in arthropods, including a high proportion of insects and also some nematodes. This intracellular symbiont can affect sex ratio with a variety of reproductive anomalies in the host, including cytoplasmic incompatibility (CI) in haplodiploids. In this study, we questioned if the parasitoid wasp, Habrobracon hebetor (Hym.: Braconidae), an important biological control agent of many lepidopteran larvae, is infected with Wolbachia. To test this, DNA was extracted from adult insects and subjected to PCR using specific primers to Wolbachia target genes. The results showed a high rate of Wolbachia infection in this parasitoid wasp. To determine the biological function of Wolbachia in H. hebetor, we removed this bacterium from the wasps using antibiotic treatment (cured wasps). Results of crossing experiments revealed that Wolbachia induced CI in H. hebetor in which cured females crossed with infected males produced only males, while both male and female progeny were observed for other crosses. Also, we showed that the presence of Wolbachia in females increased fecundity and female offspring of this parasitoid wasp. The presence of Wolbachia in the males had no significant effect on fecundity and female production, but might have incurred costs. We also investigated the effect of Wolbachia on mate choice and found that Wolbachia affects mating behavior of H. hebetor. Together, we showed that Wolbachia induces CI in H. hebetor and affects host mating behavior in favor of its transmission. Wolbachia utilize these strategies to increase the frequency of infected females in the host population.

RevDate: 2020-05-18

Chaudhary VB, Nolimal S, Sosa-Hernández MA, et al (2020)

Trait-based aerial dispersal of arbuscular mycorrhizal fungi.

The New phytologist [Epub ahead of print].

Dispersal is a key process driving local-scale community assembly and global-scale biogeography of plant symbiotic arbuscular mycorrhizal (AM) fungal communities. A trait-based approach could improve predictions regarding how AM fungal aerial dispersal varies by species. We conducted month-long collections of aerial AM fungi for 12 consecutive months in an urban mesic environment at heights of 20 m. We measured morphological functional traits of collected spores and assessed aerial AM fungal community structure both morphologically and with high-throughput sequencing. Large numbers of AM fungal spores were present in the air over the course of one year and these spores exhibited traits that facilitate aerial dispersal. Measured aerial spores were smaller than average for Glomeromycotinan fungi. Trait-based predictions indicate that nearly 1/3 of described species from diverse genera demonstrate the potential for aerial dispersal. Diversity of aerial AM fungi was relatively high (20 spore species and 17 virtual taxa) and both spore abundance and community structure shifted temporally. The prevalence of aerial dispersal in AM fungi is perhaps greater than previously indicated and a hypothesized model of AM fungal aerial dispersal mechanisms is presented. Anthropogenic soil impacts may liberate AM fungal propagules initiating the dispersal of ruderal species.

RevDate: 2020-05-18

Rejili M, BenAbderrahim MA, Mars M, et al (2020)

Novel putative rhizobial species with different symbiovars nodulate Lotus creticus and their differential preference to distinctive soil properties.

FEMS microbiology letters pii:5838745 [Epub ahead of print].

Phylogenetically diverse rhizobial strains endemic to Tunisia were isolated from symbiotic nodules of Lotus creticus, growing on different arid extremophile geographical regions of Tunisia, and speciated using multiloci-phylogenetic analysis as Neorhizobium huautlense (LCK33, LCK35, LCO42 and LCO49), Ensifer numidicus (LCD22, LCD25, LCK22 and LCK25), Ensifer meliloti (LCK8, LCK9 and LCK12), and Mesorhizobium camelthorni (LCD11, LCD13, LCD31 and LCD33). In addition, phylogenetic analyses revealed eight additional strains with previously undescribed chromosomal lineages within the genera Ensifer (LCF5, LCF6 and LCF8), Rhizobium (LCF11, LCF12 and LCF14) and Mesorhizobium (LCF16 and LCF19). Analysis using nodC gene identified five symbiovar groups, four of which were already known. The remaining group composed of two strains (LCD11 and LCD33) represented a new symbiovar of Mesorhizobium camelthorni, which we propose designating as sv. hedysari. Interestingly, we report that soil properties drive and structure the symbiosis of L. creticus and its rhizobia.

RevDate: 2020-05-18

Lee JS, Chowdhury N, Roberts JS, et al (2020)

Host surface ectonucleotidase-CD73 and the opportunistic pathogen, Porphyromonas gingivalis, cross-modulation underlies a new homeostatic mechanism for chronic bacterial survival in human epithelial cells.

Virulence, 11(1):414-429.

Cell surface nucleotide-metabolizing enzyme, ectonucleotidase-CD73, has emerged as a central component of the cellular homeostatic-machinery that counterbalances the danger-molecule (extracellular-ATP)-driven proinflammatory response in immune cells. While the importance of CD73 in microbial host fitness and symbiosis is gradually being unraveled, there remains a significant gap in knowledge of CD73 and its putative role in epithelial cells. Here, we depict a novel host-pathogen adaptation mechanism where CD73 takes a center role in the intracellular persistence of Porphyromonas gingivalis, a major colonizer of oral mucosa, using human primary gingival epithelial cell (GEC) system. Temporal analyses revealed, upon invasion into the GECs, P. gingivalis can significantly elevate the host-surface CD73 activity and expression. The enhanced and active CD73 significantly increases P. gingivalis intracellular growth in the presence of substrate-AMP and simultaneously acts as a negative regulator of reactive oxygen species (ROS) generation upon eATP treatment. The inhibition of CD73 by siRNA or by a specific inhibitor markedly increases ROS production. Moreover, CD73 and P. gingivalis cross-signaling significantly modulates pro-inflammatory interleukin-6 (IL-6) in the GECs. Conversely, exogenous treatment of the infected GECs with IL-6 suppresses the intracellular bacteria via amplified ROS generation. However, the decreased bacterial levels can be restored by overexpressing functionally active CD73. Together, these findings illuminate how the local extracellular-purine-metabolism, in which CD73 serves as a core molecular switch, can alter intracellular microbial colonization resistance. Further, host-adaptive pathogens such as P. gingivalis can target host ectonucleotidases to disarm specific innate defenses for successful intracellular persistence in mucosal epithelia.

RevDate: 2020-05-18
CmpDate: 2020-05-18

Hansen AK (2019)

Considering the microbiota to achieve reduction in the numbers of animals used in scientific studies.

Annali dell'Istituto superiore di sanita, 55(4):405-407.

Elimination of pathogens by laboratory rodent commercial vendors has substantially improved standardized conditions as well as laboratory animal welfare. However, pathogens are also important for basic activation and functioning of the immune system with consequential influences on the symbiotic bacteria composition in the individual microbiota. One of the reasons for failures of translating results from preclinical research to the clinical phase in some studies could be due to unintentional selection processes. Some recommendations are provided to increase researchers' awareness on this point, together with a practical checklist to optimize information from microbiota knowledge.

RevDate: 2020-05-18
CmpDate: 2020-05-18

Chiumento S, Roblin C, Kieffer-Jaquinod S, et al (2019)

Ruminococcin C, a promising antibiotic produced by a human gut symbiont.

Science advances, 5(9):eaaw9969.

A major public health challenge today is the resurgence of microbial infections caused by multidrug-resistant strains. Consequently, novel antimicrobial molecules are actively sought for development. In this context, the human gut microbiome is an under-explored potential trove of valuable natural molecules, such as the ribosomally-synthesized and post-translationally modified peptides (RiPPs). The biological activity of the sactipeptide subclass of RiPPs remains under-characterized. Here, we characterize an antimicrobial sactipeptide, Ruminococcin C1, purified from the caecal contents of rats mono-associated with Ruminococcus gnavus E1, a human symbiont. Its heterologous expression and post-translational maturation involving a specific sactisynthase establish a thioether network, which creates a double-hairpin folding. This original structure confers activity against pathogenic Clostridia and multidrug-resistant strains but no toxicity towards eukaryotic cells. Therefore, the Ruminococcin C1 should be considered as a valuable candidate for drug development and its producer strain R. gnavus E1 as a relevant probiotic for gut health enhancement.

RevDate: 2020-05-18
CmpDate: 2020-05-18

Wei Z, Gu Y, Friman VP, et al (2019)

Initial soil microbiome composition and functioning predetermine future plant health.

Science advances, 5(9):eaaw0759.

Plant-pathogen interactions are shaped by multiple environmental factors, making it difficult to predict disease dynamics even in relatively simple agricultural monocultures. Here, we explored how variation in the initial soil microbiome predicts future disease outcomes at the level of individual plants. We found that the composition and functioning of the initial soil microbiome predetermined whether the plants survived or succumbed to disease. Surviving plant microbiomes were associated with specific rare taxa, highly pathogen-suppressing Pseudomonas and Bacillus bacteria, and high abundance of genes encoding antimicrobial compounds. Microbiome-mediated plant protection could subsequently be transferred to the next plant generation via soil transplantation. Together, our results suggest that small initial variation in soil microbiome composition and functioning can determine the outcomes of plant-pathogen interactions under natural field conditions.

RevDate: 2020-05-18
CmpDate: 2020-05-18

Tobias NJ, Parra-Rojas C, Shi YN, et al (2019)

Cyclo(tetrahydroxybutyrate) production is sufficient to distinguish between Xenorhabdus and Photorhabdus isolates in Thailand.

Environmental microbiology, 21(8):2921-2932.

Bacteria of the genera Photorhabdus and Xenorhabdus produce a plethora of natural products to support their similar symbiotic life cycles. For many of these compounds, the specific bioactivities are unknown. One common challenge in natural product research when trying to prioritize research efforts is the rediscovery of identical (or highly similar) compounds from different strains. Linking genome sequence to metabolite production can help in overcoming this problem. However, sequences are typically not available for entire collections of organisms. Here, we perform a comprehensive metabolic screening using HPLC-MS data associated with a 114-strain collection (58 Photorhabdus and 56 Xenorhabdus) across Thailand and explore the metabolic variation among the strains, matched with several abiotic factors. We utilize machine learning in order to rank the importance of individual metabolites in determining all given metadata. With this approach, we were able to prioritize metabolites in the context of natural product investigations, leading to the identification of previously unknown compounds. The top three highest ranking features were associated with Xenorhabdus and attributed to the same chemical entity, cyclo(tetrahydroxybutyrate). This work also addresses the need for prioritization in high-throughput metabolomic studies and demonstrates the viability of such an approach in future research.

RevDate: 2020-05-18
CmpDate: 2020-05-18

Medina D, Hughey MC, Walke JB, et al (2019)

Amphibian skin fungal communities vary across host species and do not correlate with infection by a pathogenic fungus.

Environmental microbiology, 21(8):2905-2920.

Amphibian population declines caused by the fungus Batrachochytrium dendrobatidis (Bd) have prompted studies on the bacterial community that resides on amphibian skin. However, studies addressing the fungal portion of these symbiont communities have lagged behind. Using ITS1 amplicon sequencing, we examined the fungal portion of the skin microbiome of temperate and tropical amphibian species currently coexisting with Bd in nature. We assessed cooccurrence patterns between bacterial and fungal OTUs using a subset of samples for which bacterial 16S rRNA gene amplicon data were also available. We determined that fungal communities were dominated by members of the phyla Ascomycota and Basidiomycota, and also by Chytridiomycota in the most aquatic amphibian species. Alpha diversity of the fungal communities differed across host species, and fungal community structure differed across species and regions. However, we did not find a correlation between fungal diversity/community structure and Bd infection, though we did identify significant correlations between Bd and specific OTUs. Moreover, positive bacterial-fungal cooccurrences suggest that positive interactions between these organisms occur in the skin microbiome. Understanding the ecology of amphibian skin fungi, and their interactions with bacteria will complement our knowledge of the factors influencing community assembly and the overall function of these symbiont communities.

RevDate: 2020-05-08
CmpDate: 2020-05-08

Özçam M, Tocmo R, Oh JH, et al (2019)

Gut Symbionts Lactobacillus reuteri R2lc and 2010 Encode a Polyketide Synthase Cluster That Activates the Mammalian Aryl Hydrocarbon Receptor.

Applied and environmental microbiology, 85(10):.

A mechanistic understanding of microbe-host interactions is critical to developing therapeutic strategies for targeted modulation of the host immune system. Different members of the gut symbiont species Lactobacillus reuteri modulate host health by, for example, reduction of intestinal inflammation. Previously, it was shown that L. reuteri activates the aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor that plays an important role in the mucosal immune system, by the production of tryptophan catabolites. Here, we identified a novel pathway by which L. reuteri activates AhR, which is independent of tryptophan metabolism. We screened a library of 36 L. reuteri strains and determined that R2lc and 2010, strains with a pigmented phenotype, are potent AhR activators. By whole-genome sequencing and comparative genomics, we identified genes unique to R2lc and 2010. Our analyses demonstrated that R2lc harbors two genetically distinct polyketide synthase (PKS) clusters, functionally unknown (fun) and pks, each carried by a multicopy plasmid. Inactivation of pks, but not fun, abolished the ability of R2lc to activate AhR. L. reuteri 2010 has a gene cluster homologous to the pks cluster in R2lc with an identical gene organization, which is also responsible for AhR activation. In conclusion, we identified a novel PKS pathway in L. reuteri R2lc and 2010 that is responsible for AhR activation.IMPORTANCE Temporary changes in the composition of the microbiota, for example, by oral administration of probiotics, can modulate the host immune system. However, the underlying mechanisms by which probiotics interact with the host are often unknown. Here, we show that Lactobacillus reuteri R2lc and 2010 harbor an orthologous PKS gene cluster that activates the aryl hydrocarbon receptor (AhR). AhR is a ligand-activated transcription factor that plays a key role in a variety of diseases, including amelioration of intestinal inflammation. Understanding the mechanism by which a bacterium modulates the immune system is critical for applying rational selection strategies for probiotic supplementation. Finally, heterologous and/or optimized expression of PKS is a logical next step toward the development of next-generation probiotics to prevent and treat disease.

RevDate: 2020-05-17

Mielke KC, Bertuani RR, Pires FR, et al (2020)

Does Canavalia ensiformis inoculation with Bradyrhizobium sp. enhance phytoremediation of sulfentrazone-contaminated soil?.

Chemosphere, 255:127033 pii:S0045-6535(20)31226-1 [Epub ahead of print].

Symbiosis among herbicide-metabolising microorganisms and phytoremediation plants may be an efficient alternative to remediate sulfentrazone-contaminated soils. This work evaluated the bioremediation of sulfentrazone-contaminated soils by symbiosis between bacteria (Bradyrhizobium sp.) and jack bean (Canavalia ensiformis L.). The experiment was carried out in a greenhouse between March and May of 2018, in the Universidade Federal do Espírito Santo (UFES). Four doses of sulfentrazone (0, 400, 800, and 1200 g ha-1 a. i.) were tested with and without inoculation with Bradyrhizobium sp. BR 2003 (SEMIA 6156) After 80 days of cultivation, plants were cut and soil was collected for determination of the herbicide residual levels and millet bioassay. The sulfentrazone concentration was significantly reduced by plant inoculation with Bradyrhizobium sp.: on average, concentrations were 18.97%, 23.82%, and 22.10% lower than in the absence of inoculation at doses of 400, 800, and 1200 g ha-1, respectively. Symbiosis promoted a reduction of up to 65% in residual soil herbicides. Under the 1200 g ha-1 dose, inoculation promoted greater plant height than in the uninoculated plant. Regardless of the dose of sulfentrazone, the dry root mass was higher in the inoculated plants. The microbiological indicators showed satisfactory results mainly for the dose of 400 g ha-1. The results of this study highlight the potential of positive interactions between symbiotic microorganisms and leguminous species, aiming toward the phytoremediation of sulfentrazone herbicide.

RevDate: 2020-05-16

Hartmann M, Voß S, N Requena (2020)

Host-Induced Gene Silencing of Arbuscular Mycorrhizal Fungal Genes via Agrobacterium rhizogenes-Mediated Root Transformation in Medicago truncatula.

Methods in molecular biology (Clifton, N.J.), 2146:239-248.

Host-induced gene silencing (HIGS) is a methodology that allows the downregulation of genes in organisms living in close association with a host and that are not amenable or recalcitrant to genetic modifications. This method has been particularly used for oomycetes and for filamentous fungi interacting with plants, including the fungi of the arbuscular mycorrhizal symbiosis. Here, we present a protocol developed in our laboratory to downregulate genes from the obligate symbiont Rhizophagus irregularis in symbiosis with Medicago truncatula plants.

RevDate: 2020-05-16

Recorbet G, Courty PE, D Wipf (2020)

Recovery of Extra-Radical Fungal Peptides Amenable for Shotgun Protein Profiling in Arbuscular Mycorrhizae.

Methods in molecular biology (Clifton, N.J.), 2146:223-238.

In arbuscular mycorrhizal symbiosis, the belowground mycelium that develops into the soil, not only provides extensive pathways for nutrient fluxes, the occupation of different niches, and dispersal of propagules, but also has strong influences upon biogeochemical cycling. By providing a valuable overview of expression changes of most proteins, shotgun proteomics can help decipher key metabolic pathways involved in the functioning of fungal mycelia. In this protocol, we describe the combination of extra-radical mycelium growth systems with gel-based extraction of fungal peptides amenable for shotgun protein profiling, which allows gaining information about the extra-radical proteome.

RevDate: 2020-05-16

Cruz-Paredes C, ME Gavito (2020)

Isotope Labeling to Study Phosphorus Uptake in the Arbuscular Mycorrhizal Symbiosis.

Methods in molecular biology (Clifton, N.J.), 2146:213-222.

Isotope labeling enables the detection and quantification of nutrient fluxes between soil and plants through arbuscular mycorrhizal (AM) fungi. Here we describe the use of radioactive isotopes, 33P and 32P, to study the uptake of P from soil by AM fungal mycelium and its transfer to the host plant through the mycorrhizal pathway.

RevDate: 2020-05-16

Hause B, N Requena (2020)

Detection of Arbuscular Mycorrhizal Fungal Gene Expression by In Situ Hybridization.

Methods in molecular biology (Clifton, N.J.), 2146:185-196.

The complexity of the obligate symbiotic interaction of arbuscular mycorrhizal (AM) fungi and their host roots requires sophisticated molecular methods. In particular, to capture the dynamic of the interaction, cell-specific methods for gene expression analysis are required. In situ hybridization is a technique that allows to determine the location of transcript accumulation within tissues, being of special interest for these fungi that cannot be genetically modified. The method requires proper fixation and embedding methods as well as specific probes for the hybridization allowing detection of specific transcripts. In this chapter, we present a method to prepare roots, which have established a symbiosis with an arbuscular mycorrhizal fungus for the detection of fungal transcripts. This includes chemical fixation, subsequent embedding in a suitable medium, sectioning and pretreatment of sections, the hybridization procedure itself, as well as the immunological detection of RNA-RNA hybrids.

RevDate: 2020-05-16

Balestrini R, V Fiorilli (2020)

Laser Microdissection as a Useful Tool to Study Gene Expression in Plant and Fungal Partners in AM Symbiosis.

Methods in molecular biology (Clifton, N.J.), 2146:171-184.

Laser microdissection (LMD) technology has been widely applied to plant tissues, offering novel information on the role of different cell-type populations during plant-microbe interactions. In this chapter, protocols to apply the LMD approach to study plant and fungal transcript profiles in different cell-type populations from arbuscular mycorrhizal (AM) roots are described in detail, starting from the biological material preparation to gene expression analyses by RT-PCR and RT-qPCR.

RevDate: 2020-05-16

Silvestri A, Pérez-Tienda J, JA López-Ráez (2020)

Arbuscular Mycorrhizal Fungal Gene Expression Analysis by Real-Time PCR.

Methods in molecular biology (Clifton, N.J.), 2146:157-170.

Gene expression analysis is a broadly used and powerful technique in many fields of biological research. The expression pattern of specific marker genes provides an insight into complex regulatory networks and leads to the identification of relevant genes associated to specific biological processes, such as arbuscular mycorrhizal symbiosis. Among the existing gene expression analysis toolbox, reverse transcriptase coupled to quantitative polymerase chain reaction (qRT-PCR) is considered the gold standard for accurate, sensitive, fast, and relatively inexpensive measurement. However, for a correct identification of differentially expressed genes, appropriate controls are required in order to minimize nonspecific variations associated with intrinsic technical variability. In this chapter, we recommend a number of tips to use qRT-PCR analysis in mycorrhizal roots and fungal mycelium.

RevDate: 2020-05-16

Cornejo P, H Aponte (2020)

Visualization of Arbuscular Mycorrhizal Fungal Extraradical Hyphae and Spores Vitality and Activity.

Methods in molecular biology (Clifton, N.J.), 2146:61-71.

The hyphae and spores of arbuscular mycorrhizal (AM) fungi represent an essential component in the extraradical zone due to their role in nutrients and water uptake and as propagules that allow the perpetuation of the AM symbiosis over time, respectively. However, the attention of scientific literature is usually more focused on root colonization than on the study of the extraradical components of AM fungi, especially their vital, active, or functional fractions. This chapter presents some easy-to-use alternatives for staining vital, active, or functional structures of AM fungi for their subsequent microscopic visualization, such as the application of enzyme-based stains, NADPH formation, and also nucleus staining. Some modified methods for the extraction of mycelium from the soil are also presented.

RevDate: 2020-05-16

Carotenuto G, A Genre (2020)

Fluorescent Staining of Arbuscular Mycorrhizal Structures Using Wheat Germ Agglutinin (WGA) and Propidium Iodide.

Methods in molecular biology (Clifton, N.J.), 2146:53-59.

The colonization of a host plant root by arbuscular mycorrhizal (AM) fungi is a progressive process, characterized by asynchronous hyphal growth in intercellular and intracellular spaces, leading to the coexistence of diverse intraradical structures, such as hyphae, coils, arbuscules, and vesicles. In addition, the relative abundance of intercellular and intracellular fungal structures is highly dependent on root anatomy and the combination of plant and fungal species. Lastly, more than one fungal species may colonize the same root, adding a further level of complexity. For all these reasons, detailed imaging of a large number of samples is often necessary to fully assess the developmental processes and functionality of AM symbiosis. To this aim, the use of rapid and efficient staining methods that can be used routinely is crucial.We herein present a simple protocol to obtain high detail images of both overall intraradical fungal colonization pattern and fine morphology, in AM root sections of Lotus japonicus. The procedure is based on tissue clearing, fluorescent staining of fungal cell walls with fluorescein isothiocyanate-conjugated wheat germ agglutinin (FITC-WGA), and the combined counterstaining of plant cell walls with propidium iodide (PI). The resulting images can be acquired using traditional or confocal fluorescence microscopes and used for qualitative and quantitative analyses of fungal colonization, of particular interest for the comparison of mycorrhizal phenotypes between different experimental conditions or genetic backgrounds.

RevDate: 2020-05-16

Sbrana C, Pepe A, Ferrol N, et al (2020)

A Whole-Plant Culture Method to Study Structural and Functional Traits of Extraradical Mycelium.

Methods in molecular biology (Clifton, N.J.), 2146:33-41.

An in vivo whole-plant bi-dimensional experimental system has been devised and tested with different host plants, in order to obtain extraradical mycelium (ERM) produced by different arbuscular mycorrhizal fungi (AMF). In this system, a host plant germling is inoculated with AMF to establish mycorrhizal symbiosis, and, after colonization, newly formed extraradical hyphae and spores are removed. Then the mycorrhizal root system is wrapped in a nylon net and placed between membranes in a Petri dish, allowing ERM to grow on the membrane surface. Such extraradical hyphae may be used for in situ morphometric analyses or collected for molecular or biochemical assays: in the latter case, the plant with its root sandwich may be reassembled to renew mycelium production. In this experimental system, which was tested with diverse host plant species and lines, values of explored membrane surface areas and densities of ERM showed wide ranges of variation, and its length ranged from 9.7 ± 2.0 to 48.8 ± 9.9 m per plant, depending on host and AMF identity. Across the different plant-AMF combinations tested, the whole-plant system produced 2.0 ± 0.6 to 5.3 ± 0.3 mg of ERM fresh biomass per plant per harvest. This experimental system can be used for a wide range of AMF and host plants species, either establishing arbuscular mycorrhizas or other mycorrhizal interactions. ERM produced and collected in the whole-plant system is suitable for morphological, physiological, and molecular analyses, facilitating studies on the different aspects of mycorrhizal symbiotic interactions.

RevDate: 2020-05-15

Cagnano G, Lenk I, Roulund N, et al (2020)

Mycelial biomass and concentration of loline alkaloids driven by complex population structure in Epichloë uncinata and meadow fescue (Schedonorus pratensis).

Mycologia [Epub ahead of print].

Many efforts have been made to select and isolate naturally occurring animal-friendly Epichloë strains for later reinfection into elite cultivars. Often this process involves large-scale screening of Epichloë-infected wild grass populations where strains are characterized and alkaloids measured. Here, we describe for the first time the use of genotyping-by-sequencing (GBS) on a collection of 217 Epichloë-infected grasses (7 S. arundinaceum, 4 L. perenne, and 206 S. pratensis). This genotyping strategy is cheaper than complete genome sequencing, is suitable for a large number of individuals, and, when applied to endophyte-infected grasses, conveniently genotypes both organisms. In total, 6273 single nucleotide polymorphisms (SNPs) in the endophyte data set and 38 323 SNPs in the host data set were obtained. Our findings reveal a composite structure with three distinct endophyte clusters unrelated to the three main S. pratensis gene pools that have most likely spread from different glacial refugia in Eurasia. All three gene pools can establish symbiosis with E. uncinata. A comparison of the endophyte clusters with microsatellite-based fingerprinting of the same samples allows a quick test to discriminate between these clusters using two simple sequence repeats (SSRs). Concentrations of loline alkaloids and mycelial biomass are correlated and differ significantly among the plant and endophyte subpopulations; one endophyte strain has higher levels of lolines than others, and one specific host genotype is particularly suitable to host E. uncinata. These findings pave the way for targeted artificial inoculations of specific host-endophyte combinations to boost loline production in the symbiota and for genome association studies with the aim of isolating genes involved in the compatibility between meadow fescue and E. uncinata.

RevDate: 2020-05-15

Zhang G, Ahmad MZ, Chen B, et al (2020)

Lipidomic and transcriptomic profiling of developing nodules reveal the essential roles of active glycolysis and fatty acid and membrane lipid biosynthesis in soybean nodulation.

The Plant journal : for cell and molecular biology [Epub ahead of print].

Symbiotic rhizobia-legume interactions are energy-demanding processes, and the carbon supply from host cells that is critically required for nodulation and nitrogen fixation is not fully understood. The investigated lipidomic and carbohydrate profiles with the transcriptome of developing nodules revealed highly activated glycolysis, fatty acid (FA), 2-monoacylglycerol (2-MAG), and membrane lipid biosynthesis and transport during nodule development. RNA-Seq profiling of metabolic genes in roots and developing nodules highlighted the enhanced expression of genes involved in biosynthesis and transport of FAs, membrane lipids, and 2-MAG in rhizobia-soybean symbioses via the RAML-WRI-FatM-GPAT-STRL pathway, which is similar to that in legume-arbuscular mycorrhizal fungi symbiosis. The essential roles of the metabolic pathway during soybean nodulation were further supported by analysis of transgenic hairy roots overexpressing soybean GmWRI1b-OE and GmLEC2a-OE. GmLEC2a-OE hairy roots produced fewer nodules, in contrast to GmWRI1b-OE hairy roots. GmLEC2a-OE hairy roots displayed different or even opposite expression patterns of the genes involved in glycolysis and the synthesis of FAs, 2-MAG, TAG, and membrane lipids compared to GmWRI1b-OE hairy roots. Glycolysis, FA and membrane lipid biosynthesis were repressed in GmLEC2a-OE but increased in GmWRI1b-OE hairy roots, which may account for the reduced nodulation in GmLEC2a-OE hairy roots but increased nodulation in GmWRI1b-OE hairy roots. These data show that active FA, 2-MAG and membrane lipid biosynthesis are essentially required for nodulation and rhizobia-soybean symbioses. These data shed light on essential and complex lipid metabolism for soybean nodulation and nodule development, which lay the foundation for future detailed investigation of soybean nodulation.

RevDate: 2020-05-15

Harris JM, Pawlowski K, U Mathesius (2020)

Editorial: Evolution of Signaling in Plant Symbioses.

Frontiers in plant science, 11:456.

RevDate: 2020-05-15

Agtuca BJ, Stopka SA, Evans S, et al (2020)

Metabolomic profiling of wild-type and mutant soybean root nodules using laser-ablation electrospray ionization mass spectrometry reveals altered metabolism.

The Plant journal : for cell and molecular biology [Epub ahead of print].

The establishment of the nitrogen-fixing symbiosis between soybean and Bradyrhizobium japonicum is a complex process. In order to document the changes in plant metabolism due to the symbiosis, we utilized laser ablation electrospray ionization mass spectrometry (LAESI-MS) for in situ metabolic profiling of wild-type nodules, nodules infected with a B. japonicum nifH mutant unable to fix nitrogen, nodules doubly infected by both strains, and nodules formed on plants mutated in the stearoyl-acyl carrier protein desaturase (sacpd-c) gene, which were previously shown to have altered nodule ultrastructure. Results showed that the relative abundance of fatty acids, purines, and lipids was significantly changed in response to the symbiosis. The nifH mutant nodules had elevated levels of jasmonic acid (JA), correlating with signs of nitrogen deprivation. Nodules resulting from the mixed inoculant displayed similar, overlapping metabolic distributions within the sectors of effective (fix+) and ineffective (nifH mutant, fix-) endosymbionts. These data are inconsistent with the notion that plant sanctioning is cell autonomous. Nodules lacking sacpd-c displayed an elevation of soyasaponins and organic acids in the central necrotic regions. This study demonstrates the utility of LAESI-MS for high-throughput screening of plant phenotypes. Overall, nodules disrupted in the symbiosis were elevated in metabolites related to plant defense.

RevDate: 2020-05-15
CmpDate: 2020-05-15

Graça I, Mendes VM, Marques I, et al (2019)

Comparative Proteomic Analysis of Nodulated and Non-Nodulated Casuarina glauca Sieb. ex Spreng. Grown under Salinity Conditions Using Sequential Window Acquisition of All Theoretical Mass Spectra (SWATH-MS).

International journal of molecular sciences, 21(1):.

Casuarina glauca displays high levels of salt tolerance, but very little is known about how this tree adapts to saline conditions. To understand the molecular basis of C. glauca response to salt stress, we have analyzed the proteome from branchlets of plants nodulated by nitrogen-fixing Frankia Thr bacteria (NOD+) and non-nodulated plants supplied with KNO3 (KNO3+), exposed to 0, 200, 400, and 600 mM NaCl. Proteins were identified by Short Gel, Long Gradient Liquid Chromatography coupled to Tandem Mass Spectrometry and quantified by Sequential Window Acquisition of All Theoretical Mass Spectra -Mass Spectrometry. 600 proteins were identified and 357 quantified. Differentially Expressed Proteins (DEPs) were multifunctional and mainly involved in Carbohydrate Metabolism, Cellular Processes, and Environmental Information Processing. The number of DEPs increased gradually with stress severity: (i) from 7 (200 mM NaCl) to 40 (600 mM NaCl) in KNO3+; and (ii) from 6 (200 mM NaCl) to 23 (600 mM NaCl) in NOD+. Protein-protein interaction analysis identified different interacting proteins involved in general metabolic pathways as well as in the biosynthesis of secondary metabolites with different response networks related to salt stress. Salt tolerance in C. glauca is related to a moderate impact on the photosynthetic machinery (one of the first and most important stress targets) as well as to an enhancement of the antioxidant status that maintains cellular homeostasis.

RevDate: 2020-05-14

Ramongolalaina C (2020)

Dual-luciferase assay and siRNA silencing for nodD1 to study the competitiveness of Bradyrhizobium diazoefficiens USDA110 in soybean nodulation.

Microbiological research, 237:126488 pii:S0944-5013(20)30356-6 [Epub ahead of print].

The symbiosis of soybean with Bradyrhizobium diazoefficiens USDA110, which always competes with other rhizobia in the field, is of great agronomic and environmental importance. Herein, a dual-luciferase reporter assay was utilized to monitor the dynamics of two dominant bradyrhizobia infecting roots of soybean. More explicitly, luciferase-tagged B. diazoefficiens USDA110 (USDA110-FLuc) and Bradyrhizobium elkanii USDA 94 (USDA94-RLuc) were designed, co-inoculated into soybean seeds, and observed for their colonization in root nodules by bioluminescence imaging. The results showed that USDA110-FLuc initiated infection earlier than USDA94-RLuc, but its occupancy in the nodules decreased as the plant grew. A nodulation test showed that nodD1 mutant USDA110 strains, including CRISPR engineered mutants, were less competitive than wild type. I constructed siRNAs to knockdown nodD1 at different target sites and transformed them into the bacteria. Surprisingly, although siRNAs - with 3' end target sites - were able to repress up to 65% of nodD1 expression, the profiling of total RNAs with a bioanalyzer revealed that 23S/16S-rRNA ratios of siRNA-transformed and wild type USDA110 strains were similar, but lower than that of nodD1 mutant. In short, the current work - while reporting the competitiveness of B. diazoefficiens USDA110 in early occupancy of soybean nodules and the gene nodD1 as a key determinant of this infection - gives an insight on siRNA silencing in microbes, and demonstrates a highly efficient imaging approach that could entail many new avenues for many biological research fields.

RevDate: 2020-05-14

Carriche GM, Almeida L, Stüve P, et al (2020)

Regulating T cell differentiation through the polyamine spermidine.

The Journal of allergy and clinical immunology pii:S0091-6749(20)30637-0 [Epub ahead of print].

BACKGROUND: The cross-talk between the host and its microbiota plays a key role in the promotion of health. The production of metabolites, such as polyamines, by intestinal-resident bacteria is part of this symbiosis shaping host immunity. The polyamines putrescine, spermine and spermidine (SPMD) are abundant within the gastrointestinal tract, and might substantially contribute to gut immunity.

OBJECTIVE: We aimed to characterize the polyamine SPMD as a modulator of T cell differentiation and function.

METHODS: Naïve T cells were isolated from wild type (WT) mice or cord blood from healthy donors, and submitted to polarizing cytokines, with and without SPMD treatment, in order to evaluate T cell differentiation in vitro. Moreover, mice were subjected to oral supplementation of SPMD, or its precursors L-arginine, to assess the frequency and total numbers of Tregs in vivo.

RESULTS: SPMD modulates CD4+ T cell differentiation in vitro, preferentially committing naïve T cells to a regulatory phenotype. Upon SPMD treatment, activated T cells lacking the autophagy gene Atg5 fail to upregulate Foxp3 to the same extent as WT cells. These results indicate that SPMD`s polarizing effect requires an intact autophagic machinery. Furthermore, dietary supplementation with SPMD promotes homeostatic differentiation of Tregs within the gut and reduces pathology in a model of T cell transfer colitis.

CONCLUSION: Altogether, our results highlight the beneficial effects of SPMD, or L-arginine, on gut immunity, by promoting Treg development.

RevDate: 2020-05-14

Choudhary E, Bullen CK, Goel R, et al (2020)

Relative and Quantitative Phosphoproteome Analysis of Macrophages in Response to Infection by Virulent and Avirulent Mycobacteria Reveals a Distinct Role of the Cytosolic RNA Sensor RIG-I in Mycobacterium tuberculosis Pathogenesis.

Journal of proteome research [Epub ahead of print].

Comparative phosphoproteomics of Mycobacterium tuberculosis (Mtb)- and Mycobacterium bovis BCG (BCG)-infected macrophages could be instrumental in understanding the characteristic post-translational modifications of host proteins and their subsequent involvement in determining Mtb pathogenesis. To identify proteins acquiring a distinct phosphorylation status, herein, we compared the phosphorylation profile of macrophages upon exposure to Mtb and BCG. We observed a significant dephosphorylation of proteins following Mtb infection relative to those with uninfected or BCG-infected cells. A comprehensive tandem mass tag mass spectrometry (MS) approach detected ∼10% phosphosites on a variety of host proteins that are modulated in response to infection. Interestingly, the innate immune-enhancing interferon (IFN)-stimulated genes were identified as a class of proteins differentially phosphorylated during infection, including the cytosolic RNA sensor RIG-I, which has been implicated in the immune response to bacterial infection. We show that Mtb infection results in the activation of RIG-I in primary human macrophages. Studies using RIG-I knockout macrophages reveal that the Mtb-mediated activation of RIG-I promotes IFN-β, IL-1α, and IL-1β levels, dampens autophagy, and facilitates intracellular Mtb survival. To our knowledge, this is the first study providing exhaustive information on relative and quantitative changes in the global phosphoproteome profile of host macrophages that can be further explored in designing novel anti-TB drug targets. The peptide identification and MS/MS spectra have been deposited to the ProteomeXchange Consortium via the PRIDE partner repository with the dataset identifier PXD013171.

RevDate: 2020-05-14

Bolumburu C, Zamora V, Muñoz-Algarra M, et al (2020)

Trichomoniasis in a tertiary hospital of Madrid, Spain (2013-2017): prevalence and pregnancy rate, coinfections, metronidazole resistance, and endosymbiosis.

Parasitology research pii:10.1007/s00436-020-06688-2 [Epub ahead of print].

Trichomoniasis is the most prevalent curable sexually transmitted infection (STI) worldwide and a risk factor for the acquisition of other STIs and adverse pregnancy outcomes. The objectives of this study were to determine the prevalence of T. vaginalis and related coinfections in women attending a third-level hospital of Madrid (Spain). A retrospective study of 24,173 vaginal exudates from women with suspected vaginitis was conducted between 2013 and 2017. Likewise, among T. vaginalis positive samples, co-occurrence with gonorrhea, chlamydia, syphilis, VIH, Mycoplasma hominis, and Ureaplasma urealyticum was checked. Moreover, seven T. vaginalis isolates from 2017 were randomly collected for endobionts, drug resistance, and microsatellite (MS) instability determinations. The prevalence of T. vaginalis was 0.8% between 2013 and 2017. Less than 20% of patients with trichomoniasis were submitted to a complete screening for other genital pathogens. From that, two patients were coinfected with chlamydia and three with syphilis. Surprisingly, 6.4% of positive samples were diagnosed among pregnant women, showing an alarming increase from 3.2% (2014) to 10% (2017). Among the isolates randomly analyzed, five carried T. vaginalis virus, five harbored mycoplasmas, and one was metronidazole-resistant. The molecular genotyping showed a high variability in the three MS evaluated. To our knowledge, this is the first study in Spain that evaluates the prevalence of trichomoniasis in general and pregnant population and includes biomolecular determinations. These results warn about the increasing prevalence and highlight the importance of including T. vaginalis detection in routine gynecological revisions with special emphasis on childbearing age women and patients with previous STIs.

RevDate: 2020-05-14

Fu N, Wang M, Wang L, et al (2020)

Genome Sequencing and Analysis of the Fungal Symbiont of Sirex noctilio, Amylostereum areolatum: Revealing the Biology of Fungus-Insect Mutualism.

mSphere, 5(3): pii:5/3/e00301-20.

Amylostereum areolatum is the symbiotic fungus of the Eurasian woodwasp, Sirex noctilio, a globally invasive species. The mutualistic symbiont is associated with the woodwasp, assisting the damage process and providing nutrition for its insect partners. Colonization and growth of A. areolatum have essential impacts on the development and spread of S. noctilio, though the mechanism of interaction between the two has been poorly described. In this study, the first genome of this symbiotic fungus was sequenced, assembled, and annotated. The assembled A. areolatum genome was 57.5 Mb (54.51% GC content) with 15,611 protein-coding genes. We identified 580 carbohydrate-active enzymes (CAZymes), 661 genes associated with pathogen-host interactions, and 318 genes encoding transport proteins in total. The genome annotation revealed 10 terpene/phytoene synthases responsible for terpenoid biosynthesis, which could be classified into three clades. Terpene synthase gene clusters in clade II were conserved well across Russulales. In this cluster, genes encoding mevalonate kinase (MK), EGR12 (COG1557), and nonplant terpene cyclases (cd00687) were the known biosynthesis and regulatory genes. Genome sequence analysis of this fungus would prove the possibility of A. areolatum volatiles affecting the host selection of S. noctilio on a molecular basis. We further clarified that A. areolatum was a strict obligate symbiotic fungus. The wasps might protect the fungus before it was introduced into a suitable host substrate by oviposition, while the fungus would provide S. noctilio with a suitable environment and nutrients for the larval growth. These results would lay a foundation for our understanding of the mechanism of this entomogenous symbiosis.IMPORTANCESirex noctilio (F.), together with Amylostereum areolatum, a wood-decaying symbiotic fungus, causes severe damage to Pinus species worldwide. In China, it causes extensive death of Mongolian pine (Pinus sylvestris var. mongolica). There is an obligate dependency mutualism between the woodwasp and its fungus. Studies have suggested that the fungal growth rate affected the size of the wasps: larger adults emerged from sites with a higher fungus growth rate. This genome is the first reported genome sequence of a woodwasp symbiotic fungus. Genome sequence analysis of this fungus would prove the possibility of A. areolatum volatiles affecting the host selection of S. noctilio on a molecular basis. We further clarified that A. areolatum was a strict obligate symbiotic fungus and that it would provide S. noctilio with a suitable environment and with nutrients for the larval growth. These results would lay a foundation for our understanding of the mechanism of this entomogenous symbiosis.

RevDate: 2020-05-14
CmpDate: 2020-05-14

Kong HH, JA Segre (2020)

Cultivating fungal research.

Science (New York, N.Y.), 368(6489):365-366.

RevDate: 2020-05-14
CmpDate: 2020-05-14

Glowacki RWP, Pudlo NA, Tuncil Y, et al (2020)

A Ribose-Scavenging System Confers Colonization Fitness on the Human Gut Symbiont Bacteroides thetaiotaomicron in a Diet-Specific Manner.

Cell host & microbe, 27(1):79-92.e9.

Efficient nutrient acquisition in the human gut is essential for microbial persistence. Although polysaccharides have been well-studied nutrients for the gut microbiome, other resources such as nucleic acids and nucleosides are less studied. We describe several ribose-utilization systems (RUSs) that are broadly represented in Bacteroidetes and appear to have diversified to access ribose from a variety of substrates. One Bacteroides thetaiotaomicron RUS variant is critical for competitive gut colonization in a diet-specific fashion. We used molecular genetics to probe the required functions of the system and the nature of the nutrient source(s) underlying this phenotype. Two RUS-encoded ribokinases were the only components required for this effect, presumably because they generate ribose-phosphate derivatives from products of an unlinked but essential nucleoside phosphorylase. Our results underscore the extensive mechanisms that gut symbionts have evolved to access nutrients and the potential for unexpected dependencies among systems that mediate colonization and persistence.

RevDate: 2020-05-14
CmpDate: 2020-05-14

Liu Q, Liu Q, Meng H, et al (2020)

Staphylococcus epidermidis Contributes to Healthy Maturation of the Nasal Microbiome by Stimulating Antimicrobial Peptide Production.

Cell host & microbe, 27(1):68-78.e5.

The composition of the human microbiome profoundly impacts human well-being. However, the mechanisms underlying microbiome maturation are poorly understood. The nasal microbiome is of particular importance as a source of many respiratory infections. Here, we performed a large sequencing and culture-based analysis of the human nasal microbiota from different age groups. We observed a significant decline of pathogenic bacteria before adulthood, with an increase of the commensal Staphylococcus epidermidis. In seniors, this effect was partially reversed. In vitro, many S. epidermidis isolates stimulated nasal epithelia to produce antimicrobial peptides, killing pathogenic competitors, while S. epidermidis itself proved highly resistant owing to its exceptional capacity to form biofilms. Furthermore, S. epidermidis isolates with high antimicrobial peptide-inducing and biofilm-forming capacities outcompeted pathogenic bacteria during nasal colonization in vivo. Our study identifies a pivotal role of S. epidermidis in healthy maturation of the nasal microbiome, which is achieved at least in part by symbiotic cooperation with innate host defense.

RevDate: 2020-05-14
CmpDate: 2020-05-14

Kokkoris V, MM Hart (2019)

The role of in vitro cultivation on symbiotic trait and function variation in a single species of arbuscular mycorrhizal fungus.

Fungal biology, 123(10):732-744.

In vitro propagation of AM fungi using transformed root cultures (TRC) is commonly used to obtain pure AM fungal propagules for use in research and industry. Early observations indicate that such an artificial environment can alter traits and function of AM fungi over time. We hypothesized that increased in vitro cultivation may promote ruderal strategies in fungi by enhancing propagule production and reducing mutualistic quality. To examine the effect of in vitro cultivation on the trait and function of AM fungi, we inoculated plants with 11 Rhizoglomus irregulare isolates which fell along a cultivation gradient spanning 80 generations. We harvested plants at 10, 20 and 30 d post inoculation to observe differences in fungal and plant traits post infection. In vitro cultivation led to increased spore production but reduced plant shoot phosphorus. Our results indicate that in vitro propagation may indirectly select for traits that affect symbiotic quality.

RevDate: 2020-05-14
CmpDate: 2020-05-14

Planet PJ, Parker D, Ruff NL, et al (2019)

Revisiting Bacterial Interference in the Age of Methicillin-resistant Staphylococcus aureus: Insights Into Staphylococcus aureus Carriage, Pathogenicity and Potential Control.

The Pediatric infectious disease journal, 38(9):958-966.

Bacteria compete with each other for local supremacy in biologic and environmental niches. In humans, who host an array of commensal bacteria, the presence of one species or strain can sometimes prevent colonization by another, a phenomenon known as "bacterial interference." We describe how, in the 1960s, infants (and later adults) were actively inoculated with a relatively benign strain of Staphylococcus aureus, 502A, to prevent colonization with an epidemic S. aureus strain, 80/81. This introduced bacterial interference as a clinical approach to disease prevention, but little was known about the mechanisms of interference at that time. Since then, much has been learned about how bacteria interact with each other and the host to establish carriage, compete for niches and shift from harmless commensal to invasive pathogen. We provide an overview of these findings and summarize recent studies in which the genome and function of 502A were compared with those of the current epidemic strain, USA300, providing insight into differences in their invasiveness and immunogenicity. Although staphylococcal vaccines have been developed, none has yet been approved for clinical use. Further studies of staphylococcal strains and the molecular characteristics that lead to exclusion of specific bacteria from some niches may provide an alternative path to disease prevention.

RevDate: 2020-05-14
CmpDate: 2020-05-14

Zheng J, Lou L, Fan J, et al (2019)

Commensal Escherichia coli Aggravates Acute Necrotizing Pancreatitis through Targeting of Intestinal Epithelial Cells.

Applied and environmental microbiology, 85(12):.

An increase of Escherichia-Shigella was previously reported in acute necrotizing pancreatitis (ANP). We investigated whether Escherichia coli MG1655, an Escherichia commensal organism, increased intestinal injury and aggravated ANP in rats. ANP was induced by retrograde injection of 3.5% sodium taurocholate into the biliopancreatic duct. Using gut microbiota-depleted rats, we demonstrated that gut microbiota was involved in the pancreatic injury and intestinal barrier dysfunction in ANP. Using 16S rRNA gene sequencing and quantitative PCR, we found intestinal dysbiosis and a significant increase of E. coli MG1655 in ANP. Afterward, administration of E. coli MG1655 by gavage to gut microbiota-depleted rats with ANP was performed. We observed that after ANP induction, E. coli MG1655-monocolonized rats presented more severe injury in the pancreas and intestinal barrier function than gut microbiota-depleted rats. Furthermore, Toll-like receptor 4 (TLR4)/MyD88/p38 mitogen-activated protein (MAPK) and endoplasmic reticulum stress (ERS) activation in intestinal epithelial cells were also increased more significantly in the MG1655-monocolonized ANP rats. In vitro, the rat ileal epithelial cell line IEC-18 displayed aggravated tumor necrosis factor alpha-induced inflammation and loss of tight-junction proteins in coculture with E. coli MG1655, as well as TLR4, MyD88, and Bip upregulation. In conclusion, our study shows that commensal E. coli MG1655 increases TLR4/MyD88/p38 MAPK and ERS signaling-induced intestinal epithelial injury and aggravates ANP in rats. Our study also describes the harmful potential of commensal E. coli in ANP.IMPORTANCE This study describes the harmful potential of commensal E. coli in ANP, which has not been demonstrated in previous studies. Our work provides new insights into gut bacterium-ANP cross talk, suggesting that nonpathogenic commensals could also exhibit adverse effects in the context of diseases.

RevDate: 2020-05-13

Ven A, Verlinden MS, Fransen E, et al (2020)

Phosphorus addition increased carbon partitioning to autotrophic respiration but not to biomass production in an experiment with Zea mays.

Plant, cell & environment [Epub ahead of print].

Plant carbon (C) partitioning - the relative use of photosynthates for biomass production, respiration, and other plant functions - is a key but poorly understood ecosystem process. In an experiment with Zea mays, with or without arbuscular mycorrhizal fungi (AMF), we investigated the effect of phosphorus (P) fertilization and AMF on plant C partitioning. Based on earlier studies, we expected C partitioning to biomass production (i.e., biomass production efficiency; BPE) to increase with increasing P addition due to reduced C partitioning to AMF. However, although plant growth was clearly stimulated by P addition, BPE did not increase. Instead, C partitioning to autotrophic respiration increased. These results contrasted with our expectations and with a previous experiment in the same set-up where P addition increased BPE while no effect on autotropic respiration was found. The comparison of both experiments suggests a key role for AMF in explaining these contrasts. Whereas in the previous experiment substantial C partitioning to AMF reduced BPE under low P, in the current experiment, C partitioning to AMF was too low to directly influence BPE. Our results illustrate the complex influence of nutrient availability and mycorrhizal symbiosis on plant C partitioning. This article is protected by copyright. All rights reserved.

RevDate: 2020-05-13
CmpDate: 2020-05-13

Chan WY, Peplow LM, Menéndez P, et al (2019)

The roles of age, parentage and environment on bacterial and algal endosymbiont communities in Acropora corals.

Molecular ecology, 28(16):3830-3843.

The bacterial and microalgal endosymbiont (Symbiodiniaceae spp.) communities associated with corals have important roles in their health and resilience, yet little is known about the factors driving their succession during early coral life stages. Using 16S rRNA gene and ITS2 metabarcoding, we compared these communities in four Acropora coral species and their hybrids obtained from two laboratory crosses (Acropora tenuis × Acropora loripes and Acropora sarmentosa × Acropora florida) across the parental, recruit (7 months old) and juvenile (2 years old) life stages. We tested whether microbiomes differed between (a) life stages, (b) hybrids and purebreds, and (c) treatment conditions (ambient/elevated temperature and pCO2). Microbial communities of early life stage corals were highly diverse, lacked host specificity and were primarily determined by treatment conditions. Over time, a winnowing process occurred, and distinct microbial communities developed between the two species pair crosses by 2 years of age, irrespective of hybrid or purebred status. These findings suggest that the microbial communities of corals have a period of flexibility prior to adulthood, which can be valuable to future research aimed at the manipulation of coral microbial communities.

RevDate: 2020-05-12

Yu MC, Dreyer N, Kolbasov GA, et al (2020)

Sponge symbiosis is facilitated by adaptive evolution of larval sensory and attachment structures in barnacles.

Proceedings. Biological sciences, 287(1927):20200300.

Symbiotic relations and range of host usage are prominent in coral reefs and crucial to the stability of such systems. In order to explain how symbiotic relations are established and evolve, we used sponge-associated barnacles to ask three questions. (1) Does larval settlement on sponge hosts require novel adaptations facilitating symbiosis? (2) How do larvae settle and start life on their hosts? (3) How has this remarkable symbiotic lifestyle involving many barnacle species evolved? We found that the larvae (cyprids) of sponge-associated barnacles show a remarkably high level of interspecific variation compared with other barnacles. We document that variation in larval attachment devices are specifically related to properties of the surface on which they attach and metamorphose. Mapping of the larval and sponge surface features onto a molecular-based phylogeny showed that sponge symbiosis evolved separately at least three times within barnacles, with the same adaptive features being found in all larvae irrespective of phylogenetic relatedness. Furthermore, the metamorphosis of two species proceeded very differently, with one species remaining superficially on the host and developing a set of white calcareous structures, the other embedding itself into the live host tissue almost immediately after settlement. We argue that such a high degree of evolutionary flexibility of barnacle larvae played an important role in the successful evolution of complex symbiotic relationships in both coral reefs and other marine systems.

RevDate: 2020-05-12

Sibponkrung S, Kondo T, Tanaka K, et al (2020)

Co-Inoculation of Bacillusvelezensis Strain S141 and Bradyrhizobium Strains Promotes Nodule Growth and Nitrogen Fixation.

Microorganisms, 8(5): pii:microorganisms8050678.

The objective of this research was to evaluate the PGPR effect on nodulation and nitrogen-fixing efficiency of soybean (Glycine max (L.) Merr.) by co-inoculation with Bradyrhizobiumdiazoefficiens USDA110. Co-inoculation of Bacillusvelezensis S141 with USDA110 into soybean resulted in enhanced nodulation and N2-fixing efficiency by producing larger nodules. To understand the role of S141 on soybean and USDA110 symbiosis, putative genes related to IAA biosynthesis were disrupted, suggesting that co-inoculation of USDA110 with S141ΔyhcX reduces the number of large size nodules. It was revealed that yhcX may play a major role in IAA biosynthesis in S141 as well as provide a major impact on soybean growth promotion. The disruption of genes related to cytokinin biosynthesis and co-inoculation of USDA110 with S141ΔIPI reduced the number of very large size nodules, and it appears that IPI might play an important role in nodule size of soybean-Bradyrhizobium symbiosis. However, it was possible that not only IAA and cytokinin but also some other substances secreted from S141 facilitate Bradyrhizobium to trigger bigger nodule formation, resulting in enhanced N2-fixation. Therefore, the ability of S141 with Bradyrhizobium co-inoculation to enhance soybean N2-fixation strategy could be further developed for supreme soybean inoculants.

RevDate: 2020-05-11

Patta I, Madhok A, Khare S, et al (2020)

Dynamic regulation of chromatin organizer SATB1 via TCR-induced alternative promoter switch during T-cell development.

Nucleic acids research pii:5835819 [Epub ahead of print].

The chromatin organizer SATB1 is highly enriched in thymocytes and is essential for T-cell development. Although SATB1 regulates a large number of genes important for T-cell development, the mechanism(s) regulating expression of SATB1 during this process remain elusive. Using chromatin immune precipitation-seq-based occupancy profiles of H3K4me3 and H3Kme1 at Satb1 gene locus, we predicted four different alternative promoters of Satb1 in mouse thymocytes and characterized them. The expression of Satb1 transcript variants with distinct 5' UTRs occurs in a stage-specific manner during T-cell development and is dependent on TCR signaling. The observed discrepancy between the expression levels of SATB1 mRNA and protein in developing thymocytes can be explained by the differential translatability of Satb1 transcript variants as confirmed by polysome profiling and in vitro translation assay. We show that Satb1 alternative promoters exhibit lineage-specific chromatin accessibility during T-cell development from progenitors. Furthermore, TCF1 regulates the Satb1 P2 promoter switch during CD4SP development, via direct binding to the Satb1 P2 promoter. CD4SP T cells from TCF1 KO mice exhibit downregulation of P2 transcript variant expression as well as low levels of SATB1 protein. Collectively, these results provide unequivocal evidence toward alternative promoter switch-mediated developmental stage-specific regulation of SATB1 in thymocytes.

RevDate: 2020-05-11

Tong H, Cai L, Zhou G, et al (2020)

Correlations Between Prokaryotic Microbes and Stress-Resistant Algae in Different Corals Subjected to Environmental Stress in Hong Kong.

Frontiers in microbiology, 11:686.

Coral reefs are extremely vulnerable to global climate change, as evidenced by increasing bleaching events. Previous studies suggest that both algal and microbial partners benefit coral hosts, but the nature of interactions between Symbiodiniaceae and prokaryotic microbes and their effects on coral hosts remains unclear. In the present study, we examined correlations between Symbiodiniaceae and prokaryotic microbes in Montipora spp. and Porites lutea sampled from two sites in Hong Kong with contrasting environmental conditions in March and October 2014. The results showed that the prokaryotic microbial communities had adaptable structures in both Montipora spp. and P. lutea, and environmental conditions had greater effects on the algal/microbial communities in Montipora spp. than in P. lutea. Further network analysis revealed a greater number of prokaryotic microbes were significantly correlated with potentially stress-resistant Symbiodiniaceae in P. lutea than in Montipora spp. Stress-resistant Symbiodiniaceae played more important roles in the community and in the algal-microbial correlations in P. lutea than in Montipora spp. Since P. lutea is faring better in Hong Kong as the seawater temperature gradually increases, the results suggest that the correlations between stress-resistant algae and prokaryotic microbes could provide a compensation mechanism allowing coral hosts to adapt to higher temperatures, particularly as the prokaryotic microbes correlated with Symbiodiniaceae provide the ecological functions of photosynthesis and nitrogen fixation.

RevDate: 2020-05-11

Ben-Yosef M, Rot A, Mahagna M, et al (2020)

Coxiella-Like Endosymbiont of Rhipicephalus sanguineus Is Required for Physiological Processes During Ontogeny.

Frontiers in microbiology, 11:493.

Obligatory hematophagous arthropods such as lice, bugs, flies, and ticks harbor bacterial endosymbionts that are expected to complement missing essential nutrients in their diet. Genomic and some experimental evidence support this expectation. Hard ticks (Acari: Ixodidae) are associated with several lineages of bacterial symbionts, and very few were experimentally shown to be essential to some aspects of tick's fitness. In order to pinpoint the nature of interactions between hard ticks and their symbionts, we tested the effect of massive elimination of Coxiella-like endosymbionts (CLE) by antibiotics on the development and fitness of the brown dog tick (Rhipicephalus sanguineus). Administration of ofloxacin to engorged (blood fed) nymphs resulted in significant and acute reduction of their CLE loads - an effect that also persisted in subsequent life stages (aposymbiotic ticks). As a result, the post-feeding development of aposymbiotic female (but not male) nymphs was delayed. Additionally, aposymbiotic adult females needed a significantly prolonged feeding period in order to replete (detach from host), and had reduced engorgement weight and a lower capacity to produce eggs. Consequently, their fecundity and fertility were significantly reduced. Eggs produced by aposymbiotic females were free of CLE, and the resulting aposymbiotic larvae were unable to feed successfully. Our findings demonstrate that the observed fitness effects are due to CLE reduction and not due to antibiotic administration. Additionally, we suggest that the contribution of CLE is not mandatory for oocyte development and embryogenesis, but is required during feeding in females, when blood meal processing and tissue buildup are taking place. Presumably, under these extreme physiological demands, CLE contribute to R. sanguineus through supplementing essential micro- and macronutrients. Further nutrient complementary studies are required to support this hypothesis.

RevDate: 2020-05-11
CmpDate: 2020-05-11

McKenzie MR, Templeman MA, MJ Kingsford (2020)

Detecting effects of herbicide runoff: The use of Cassiopea maremetens as a biomonitor to hexazinone.

Aquatic toxicology (Amsterdam, Netherlands), 221:105442.

Herbicides are an integral part of global agricultural activity but can be advected into local drainages that can discharge to coastal marine systems. Herbicide runoff can impact coastal marine organisms, including those associated with coral reefs and coastal mangrove forests. In this study, the symbiotic sedentary jellyfish Cassiopea maremetens were exposed to analytical grade hexazinone to determine their sensitivity and potential for recovery after exposure to a press herbicide event of 14 days followed by a recovery period of matching duration. Bell surface area, photosynthetic yield (i.e. effective quantum yield, EQY), statolith count and zooxanthellae density were analyzed. Most metrics demonstrated significant decreases when exposed to higher concentrations of hexazinone, while EQY was significantly decreased at exposure concentrations from 31 μg/L hexazinone and above. In contrast, zooxanthellae density (cells/mm2) increased in the highest concentrations compared to control animals. At the end of the exposure period the EC50 for bell surface area, EQY, and statolith count were 176 μg/L, 81.96 μg/L, and 304.3 μg/L, respectively. Jellyfish were able to recover to similar start values for all measured metrics at the end of the 14-day recovery period, with EQY showing recovery by Day 7 of the recovery period. This study demonstrated that statolith counts as an estimate of age were not affected by herbicides. We conclude that the depressed metrics from herbicide related impacts of C. maremetens are effective indicators of a relatively recent herbicide perturbation in that the recovery timeframe for these jellyfish is relatively short.

RevDate: 2020-05-11
CmpDate: 2020-05-11

Zhang D, Wang Y, He K, et al (2020)

Wolbachia limits pathogen infections through induction of host innate immune responses.

PloS one, 15(2):e0226736.

BACKGROUND: Wolbachia has been reported to suppress a variety of pathogen infections in mosquitoes, but the mechanism is undefined. Two possibilities have been proposed. One is that Wolbachia activates host immune responses, and the other one is that Wolbachia competes with pathogens for limited nutrients.

In this study, we compared host immune responses and the densities of two different strains of Wolbachia in naturally occurring parental and artificially created hybrid host genetic backgrounds. No significant difference in Wolbachia density was found between these hosts. We found that Wolbachia could activate host innate immune responses when the host genetic profile was different from that of its natural host. When these hosts were challenged with pathogenic bacteria, mosquitoes in new host-Wolbachia symbioses had a higher survival rate than in old host-Wolbachia symbioses.

CONCLUSIONS/SIGNIFICANCE: The presence of Wolbachia per se does not necessarily affect pathogen infections, suggesting that a competition for limited nutrients is not the main reason for Wolbachia-mediated pathogen suppression. Instead, host immune responses are responsible for it. The elucidation of an immunity nature of PI is important to guide future practice: Wolbachia may be genetically engineered to be more immunogenic, it is desired to search and isolate more strains of Wolbachia, and test more host-Wolbachia symbioses for future applications. Our results also suggest Wolbachia-based PI may be applied to naturally Wolbachia-infected mosquito populations, and extend to the control of a broader range of mosquito-borne diseases.

RevDate: 2020-05-11
CmpDate: 2020-05-11

Ramos-Robles M, Vargas-Cardoso OR, Corona-López AM, et al (2020)

Spatio-temporal variation of Cerambycidae-host tree interaction networks.

PloS one, 15(2):e0228880.

Despite its high ecological importance, the commensal interactions at community level are poorly studied. In tropical dry forests (TDF) there is a great diversity of species adapted to the high seasonality that characterizes them; however, little is known regarding how the spatial and temporal availability of resources generates changes in the pattern of commensal interactions. We experimentally studied changes in the diversity, composition, and pattern of interactions in spatio-temporal associations between the saproxylophagous beetles and their host trees in a TDF in Morelos, Mexico. A total of 65 host tree species were selected, from which 16 wood sections were obtained per species. These sections were exposed in the field to allow oviposition by the cerambycids under four different (spatio-temporal) treatments. We analyzed the network structure and generated indices at species level (i.e., specialization, species strength, and effective partners) and those related to physical characteristics of the wood (hardness and degradation rate) and the cerambycids (body size). In total, 1,323 individuals of 57 species of cerambycids emerged. Our results showed that, independently of the space and time, the network presented a nested and modular structure, with a high specialization degree and a high turnover of cerambycid species and their interactions. In general, we found that the cerambycids are mostly associated with softwood species with a lower decomposition rate of wood, as well as with the most abundant host species. The commensalistic interactions between the cerambycids and their host trees are highly specialized but are not spatio-temporally static. The high turnover in the interactions is caused by the emergence patterns of cerambycids, which seem to restrict their use to certain species. The knowledge of the spatio-temporal variation in Cerambycidae-host tree interactions allows us to predict how environmental and structural changes in the habitat can modify the species ensemble, and therefore its interactions.

RevDate: 2020-05-11
CmpDate: 2020-05-11

Perlmutter JI, SR Bordenstein (2020)

Microorganisms in the reproductive tissues of arthropods.

Nature reviews. Microbiology, 18(2):97-111.

Microorganisms that reside within or transmit through arthropod reproductive tissues have profound impacts on host reproduction, health and evolution. In this Review, we discuss select principles of the biology of microorganisms in arthropod reproductive tissues, including bacteria, viruses, protists and fungi. We review models of specific symbionts, routes of transmission, and the physiological and evolutionary outcomes for both hosts and microorganisms. We also identify areas in need of continuing research, to answer the fundamental questions that remain in fields within and beyond arthropod-microorganism associations. New opportunities for research in this area will drive a broader understanding of major concepts as well as the biodiversity, mechanisms and translational applications of microorganisms that interact with host reproductive tissues.

RevDate: 2020-05-11
CmpDate: 2020-05-11

Booth SC, WPJ Smith (2020)

Light sheets unveil host-microorganism interactions.

Nature reviews. Microbiology, 18(2):65.

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ESP Quick Facts

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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.

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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.

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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.

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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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Selected Bibliographies

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