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1.
Nat Commun ; 12(1): 4160, 2021 07 06.
Artigo em Inglês | MEDLINE | ID: mdl-34230473

RESUMO

Nitrogen fixation has a critical role in marine primary production, yet our understanding of marine nitrogen-fixers (diazotrophs) is hindered by limited observations. Here, we report a quantitative image analysis pipeline combined with mapping of molecular markers for mining >2,000,000 images and >1300 metagenomes from surface, deep chlorophyll maximum and mesopelagic seawater samples across 6 size fractions (<0.2-2000 µm). We use this approach to characterise the diversity, abundance, biovolume and distribution of symbiotic, colony-forming and particle-associated diazotrophs at a global scale. We show that imaging and PCR-free molecular data are congruent. Sequence reads indicate diazotrophs are detected from the ultrasmall bacterioplankton (<0.2 µm) to mesoplankton (180-2000 µm) communities, while images predict numerous symbiotic and colony-forming diazotrophs (>20 µm). Using imaging and molecular data, we estimate that polyploidy can substantially affect gene abundances of symbiotic versus colony-forming diazotrophs. Our results support the canonical view that larger diazotrophs (>10 µm) dominate the tropical belts, while unicellular cyanobacterial and non-cyanobacterial diazotrophs are globally distributed in surface and mesopelagic layers. We describe co-occurring diazotrophic lineages of different lifestyles and identify high-density regions of diazotrophs in the global ocean. Overall, we provide an update of marine diazotroph biogeographical diversity and present a new bioimaging-bioinformatic workflow.


Assuntos
Impressão Molecular/métodos , Fixação de Nitrogênio/genética , Nitrogênio/metabolismo , Água do Mar/química , Organismos Aquáticos , Bactérias/genética , Bactérias/metabolismo , Cianobactérias/genética , Cianobactérias/metabolismo , Fixação de Nitrogênio/fisiologia , Oceanos e Mares , Filogenia , Plâncton/metabolismo , Água do Mar/microbiologia , Simbiose/genética , Simbiose/fisiologia
2.
Int J Mol Sci ; 22(12)2021 Jun 09.
Artigo em Inglês | MEDLINE | ID: mdl-34207734

RESUMO

Rhizobia are soil proteobacteria able to engage in a nitrogen-fixing symbiotic interaction with legumes that involves the rhizobial infection of roots and the bacterial invasion of new organs formed by the plant in response to the presence of appropriate bacterial partners. This interaction relies on a complex molecular dialogue between both symbionts. Bacterial N-acetyl-glucosamine oligomers called Nod factors are indispensable in most cases for early steps of the symbiotic interaction. In addition, different rhizobial surface polysaccharides, such as exopolysaccharides (EPS), may also be symbiotically relevant. EPS are acidic polysaccharides located out of the cell with little or no cell association that carry out important roles both in free-life and in symbiosis. EPS production is very complexly modulated and, frequently, co-regulated with Nod factors, but the type of co-regulation varies depending on the rhizobial strain. Many studies point out a signalling role for EPS-derived oligosaccharides in root infection and nodule invasion but, in certain symbiotic couples, EPS can be dispensable for a successful interaction. In summary, the complex regulation of the production of rhizobial EPS varies in different rhizobia, and the relevance of this polysaccharide in symbiosis with legumes depends on the specific interacting couple.


Assuntos
Fabaceae , Raízes de Plantas , Polissacarídeos Bacterianos/metabolismo , Rhizobium/metabolismo , Simbiose/fisiologia , Fabaceae/metabolismo , Fabaceae/microbiologia , Raízes de Plantas/metabolismo , Raízes de Plantas/microbiologia
3.
BMC Plant Biol ; 21(1): 274, 2021 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-34130630

RESUMO

BACKGROUND: Rhizobium-legume symbiosis is a specific, coordinated interaction that results in the formation of a root nodule, where biological nitrogen fixation occurs. NADPH oxidases, or Respiratory Burst Oxidase Homologs (RBOHs) in plants, are enzymes that generate superoxide (O2 •-). Superoxide produces other reactive oxygen species (ROS); these ROS regulate different stages of mutualistic interactions. For example, changes in ROS levels are thought to induce ROS scavenging, cell wall remodeling, and changes in phytohormone homeostasis during symbiotic interactions. In common bean (Phaseolus vulgaris), PvRbohB plays a key role in the early stages of nodulation. RESULTS: In this study, to explore the role of PvRbohB in root nodule symbiosis, we analyzed transcriptomic data from the roots of common bean under control conditions (transgenic roots without construction) and roots with downregulated expression of PvRbohB (by RNA interference) non-inoculated and inoculated with R. tropici. Our results suggest that ROS produced by PvRBOHB play a central role in infection thread formation and nodule organogenesis through crosstalk with flavonoids, carbon metabolism, cell cycle regulation, and the plant hormones auxin and cytokinin during the early stages of this process. CONCLUSIONS: Our findings provide important insight into the multiple roles of ROS in regulating rhizobia-legume symbiosis.


Assuntos
Carbono/metabolismo , Ciclo Celular , NADPH Oxidases/metabolismo , Phaseolus/enzimologia , Nodulação , Raízes de Plantas/enzimologia , Simbiose/fisiologia , Phaseolus/genética , Phaseolus/microbiologia , Raízes de Plantas/microbiologia , Espécies Reativas de Oxigênio/metabolismo , Rhizobium/fisiologia , Transcriptoma
4.
Methods Mol Biol ; 2295: 81-97, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34047973

RESUMO

Algae are ecologically important organisms and are widely used for basic research, with a focus on for example photosynthesis, evolution, and lipid metabolism. Many biosynthetic pathways of algal lipids have been deciphered using available genomic information. Here we describe methods for lipid analyses from three representative algae, including Archaeplastida, the SAR lineage (Stramenopiles, Alveolata, Rhizaria), and Excavata. Archaeplastida acquired their plastids by primary endosymbiosis, and the others by secondary endosymbiosis with a Rhodophyceae-type plastid in SAR and a Chlorophyceae-type plastid in Excavata (Euglenozoa). Analytical methods for these algae are described for membrane lipids and neutral lipids including triacylglycerol and wax esters.


Assuntos
Carofíceas/metabolismo , Euglênidos/metabolismo , Lipídeos/análise , Caráceas/genética , Evolução Molecular , Microalgas/metabolismo , Fotossíntese/fisiologia , Filogenia , Plastídeos/metabolismo , Rodófitas/genética , Estramenópilas/genética , Simbiose/fisiologia
5.
Zoolog Sci ; 38(2): 140-147, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33812353

RESUMO

Symbiotic associations with beneficial microorganisms endow a variety of host animals with adaptability to the environment. Stable transmission of symbionts across host generations is a key event in the maintenance of symbiotic associations through evolutionary time. However, our understanding of the mechanisms of symbiont transmission remains fragmentary. The deep-sea clam Phreagena okutanii harbors chemoautotrophic intracellular symbiotic bacteria in gill epithelial cells, and depends on these symbionts for nutrition. In this study, we focused on the association of these maternally transmitted symbionts with ovarian germ cells in juvenile female clams. First, we established a sex identification method for small P. okutanii individuals, and morphologically classified female germ cells observed in the ovary. Then, we investigated the association of the endosymbiotic bacteria with germ cells. We found that the symbionts were localized on the outer surface of the cell membrane of primary oocytes and not within the cluster of oogonia. Based on our findings, we discuss the processes and mechanisms of symbiont vertical transmission in P. okutanii.


Assuntos
Bactérias/classificação , Bivalves/microbiologia , Simbiose/fisiologia , Animais , Feminino , Brânquias/microbiologia , Oócitos/microbiologia
6.
Arch Insect Biochem Physiol ; 106(4): e21776, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33644932

RESUMO

Maternally inherited endosymbiotic bacterium Wolbachia infects Drosophila melanogaster populations worldwide. Its genetic diversity includes several closely related genotypes, which can be attributed to two main genotype groups: wMel and wMelCS. Here, we studied eight D. melanogaster lines carrying the nuclear background of wild type interbred Bi90 line and cytoplasmic backgrounds with or without Wolbachia of different origin, each of which belongs to wMelCS genotype group. We analyzed the effect these seven Wolbachia strains had on the heat stress resistance and dopamine metabolism in D. melanogaster females. Survival under heat stress (38°C, 3 h 30 min) was increased only in the line infected with bacteria of the wMelPlus strain. At the same time, the activity of alkaline phosphatase (an enzyme regulating the pool of dopamine precursor tyrosine) was increased under normal conditions in females infected with all strains under study and retained the response to heat stress typical for the uninfected line. Thus, we found the unique Wolbachia strain that provides an increase of the host stress resistance, and demonstrated that the mechanism of this resistance is not dopamine-mediated.


Assuntos
Drosophila melanogaster/microbiologia , Termotolerância , Wolbachia/genética , Fosfatase Alcalina/metabolismo , Animais , Dopamina/metabolismo , Drosophila melanogaster/metabolismo , Genótipo , Resposta ao Choque Térmico , Simbiose/fisiologia , Termotolerância/genética , Termotolerância/fisiologia
7.
Nat Commun ; 12(1): 1890, 2021 03 25.
Artigo em Inglês | MEDLINE | ID: mdl-33767155

RESUMO

Photosynthetic organisms have developed diverse antennas composed of chromophorylated proteins to increase photon capture. Cryptophyte algae acquired their photosynthetic organelles (plastids) from a red alga by secondary endosymbiosis. Cryptophytes lost the primary red algal antenna, the red algal phycobilisome, replacing it with a unique antenna composed of αß protomers, where the ß subunit originates from the red algal phycobilisome. The origin of the cryptophyte antenna, particularly the unique α subunit, is unknown. Here we show that the cryptophyte antenna evolved from a complex between a red algal scaffolding protein and phycoerythrin ß. Published cryo-EM maps for two red algal phycobilisomes contain clusters of unmodelled density homologous to the cryptophyte-αß protomer. We modelled these densities, identifying a new family of scaffolding proteins related to red algal phycobilisome linker proteins that possess multiple copies of a cryptophyte-α-like domain. These domains bind to, and stabilise, a conserved hydrophobic surface on phycoerythrin ß, which is the same binding site for its primary partner in the red algal phycobilisome, phycoerythrin α. We propose that after endosymbiosis these scaffolding proteins outcompeted the primary binding partner of phycoerythrin ß, resulting in the demise of the red algal phycobilisome and emergence of the cryptophyte antenna.


Assuntos
Criptófitas/fisiologia , Fotossíntese/fisiologia , Ficobilissomas/metabolismo , Porphyridium/metabolismo , Porphyridium/fisiologia , Sequência de Aminoácidos , Sítios de Ligação , Ficoeritrina/metabolismo , Plastídeos/genética , Simbiose/fisiologia
8.
Plant Physiol ; 185(1): 196-209, 2021 02 25.
Artigo em Inglês | MEDLINE | ID: mdl-33631809

RESUMO

Legumes play an important role in the soil nitrogen availability via symbiotic nitrogen fixation (SNF). Phosphate (Pi) deficiency severely impacts SNF because of the high Pi requirement of symbiosis. Whereas PHT1 transporters are involved in Pi uptake into nodules, it is unknown how Pi is transferred from the plant infected cells to nitrogen-fixing bacteroids. We hypothesized that Medicago truncatula genes homologous to Arabidopsis PHO1, encoding a vascular apoplastic Pi exporter, are involved in Pi transfer to bacteroids. Among the seven MtPHO1 genes present in M. truncatula, we found that two genes, namely MtPHO1.1 and MtPHO1.2, were broadly expressed across the various nodule zones in addition to the root vascular system. Expressions of MtPHO1.1 and MtPHO1.2 in Nicotiana benthamiana mediated specific Pi export. Plants with nodule-specific downregulation of both MtPHO1.1 and MtPHO1.2 were generated by RNA interference (RNAi) to examine their roles in nodule Pi homeostasis. Nodules of RNAi plants had lower Pi content and a three-fold reduction in SNF, resulting in reduced shoot growth. Whereas the rate of 33Pi uptake into nodules of RNAi plants was similar to control, transfer of 33Pi from nodule cells into bacteroids was reduced and bacteroids activated their Pi-deficiency response. Our results implicate plant MtPHO1 genes in bacteroid Pi homeostasis and SNF via the transfer of Pi from nodule infected cells to bacteroids.


Assuntos
Medicago truncatula/genética , Fixação de Nitrogênio/fisiologia , Proteínas de Transporte de Fosfato/genética , Proteínas de Transporte de Fosfato/fisiologia , Nódulos Radiculares de Plantas/fisiologia , Sinorhizobium meliloti/fisiologia , Simbiose/fisiologia , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Fixação de Nitrogênio/genética , Nódulos Radiculares de Plantas/genética , Simbiose/genética
9.
Nat Commun ; 12(1): 718, 2021 02 02.
Artigo em Inglês | MEDLINE | ID: mdl-33531484

RESUMO

Ficus (figs) and their agaonid wasp pollinators present an ecologically important mutualism that also provides a rich comparative system for studying functional co-diversification throughout its coevolutionary history (~75 million years). We obtained entire nuclear, mitochondrial, and chloroplast genomes for 15 species representing all major clades of Ficus. Multiple analyses of these genomic data suggest that hybridization events have occurred throughout Ficus evolutionary history. Furthermore, cophylogenetic reconciliation analyses detect significant incongruence among all nuclear, chloroplast, and mitochondrial-based phylogenies, none of which correspond with any published phylogenies of the associated pollinator wasps. These findings are most consistent with frequent host-switching by the pollinators, leading to fig hybridization, even between distantly related clades. Here, we suggest that these pollinator host-switches and fig hybridization events are a dominant feature of fig/wasp coevolutionary history, and by generating novel genomic combinations in the figs have likely contributed to the remarkable diversity exhibited by this mutualism.


Assuntos
Ficus/fisiologia , Vespas/fisiologia , Animais , Evolução Biológica , Hibridização Genética , Filogenia , Polinização/fisiologia , Simbiose/fisiologia
10.
Nat Commun ; 12(1): 1165, 2021 02 19.
Artigo em Inglês | MEDLINE | ID: mdl-33608555

RESUMO

Animals endemic to deep-sea hydrothermal vents often form obligatory symbioses with bacteria, maintained by intricate host-symbiont interactions. Most genomic studies on holobionts have not investigated both sides to similar depths. Here, we report dual symbiosis in the peltospirid snail Gigantopelta aegis with two gammaproteobacterial endosymbionts: a sulfur oxidiser and a methane oxidiser. We assemble high-quality genomes for all three parties, including a chromosome-level host genome. Hologenomic analyses reveal mutualism with nutritional complementarity and metabolic co-dependency, highly versatile in transporting and using chemical energy. Gigantopelta aegis likely remodels its immune system to facilitate dual symbiosis. Comparisons with Chrysomallon squamiferum, a confamilial snail with a single sulfur-oxidising gammaproteobacterial endosymbiont, show that their sulfur-oxidising endosymbionts are phylogenetically distant. This is consistent with previous findings that they evolved endosymbiosis convergently. Notably, the two sulfur-oxidisers share the same capabilities in biosynthesising nutrients lacking in the host genomes, potentially a key criterion in symbiont selection.


Assuntos
Bactérias/genética , Fontes Hidrotermais/microbiologia , Caramujos/genética , Caramujos/microbiologia , Simbiose/genética , Animais , Bactérias/metabolismo , Gammaproteobacteria/genética , Gammaproteobacteria/metabolismo , Expressão Gênica , Genoma Bacteriano , Genômica , Filogenia , Caramujos/metabolismo , Enxofre/metabolismo , Simbiose/fisiologia , Transcriptoma
11.
Int J Mol Sci ; 22(2)2021 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-33445801

RESUMO

This study focused on the interactions of pea (Pisum sativum L.) plants with phytopathogenic and beneficial fungi. Here, we examined whether the lysin-motif (LysM) receptor-like kinase PsLYK9 is directly involved in the perception of long- and short-chain chitooligosaccharides (COs) released after hydrolysis of the cell walls of phytopathogenic fungi and identified in arbuscular mycorrhizal (AM) fungal exudates. The identification and analysis of pea mutants impaired in the lyk9 gene confirmed the involvement of PsLYK9 in symbiosis development with AM fungi. Additionally, PsLYK9 regulated the immune response and resistance to phytopathogenic fungi, suggesting its bifunctional role. The existence of co-receptors may provide explanations for the potential dual role of PsLYK9 in the regulation of interactions with pathogenic and AM fungi. Co-immunoprecipitation assay revealed that PsLYK9 and two proposed co-receptors, PsLYR4 and PsLYR3, can form complexes. Analysis of binding capacity showed that PsLYK9 and PsLYR4, synthesized as extracellular domains in insect cells, were able to bind the deacetylated (DA) oligomers CO5-DA-CO8-DA. Our results suggest that the receptor complex consisting of PsLYK9 and PsLYR4 can trigger a signal pathway that stimulates the immune response in peas. However, PsLYR3 seems not to be involved in the perception of CO4-5, as a possible co-receptor of PsLYK9.


Assuntos
Quitina/análogos & derivados , Ervilhas/metabolismo , Proteínas de Plantas/metabolismo , Animais , Linhagem Celular , Parede Celular/metabolismo , Parede Celular/microbiologia , Quitina/metabolismo , Hidrólise , Insetos/metabolismo , Micorrizas/metabolismo , Ervilhas/microbiologia , Imunidade Vegetal/fisiologia , Raízes de Plantas/metabolismo , Raízes de Plantas/microbiologia , Células Sf9 , Transdução de Sinais/fisiologia , Simbiose/fisiologia
12.
Nat Plants ; 7(1): 73-86, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33452487

RESUMO

Symbiosis between soybean (Glycine max) and rhizobia is essential for efficient nitrogen fixation. Rhizobial effectors secreted through the type-III secretion system are key for mediating the interactions between plants and rhizobia, but the molecular mechanism remains largely unknown. Here, our genome-wide association study for nodule number identified G. max Nodule Number Locus 1 (GmNNL1), which encodes a new R protein. GmNNL1 directly interacts with the nodulation outer protein P (NopP) effector from Bradyrhizobium USDA110 to trigger immunity and inhibit nodulation through root hair infection. The insertion of a 179 bp short interspersed nuclear element (SINE)-like transposon into GmNNL1 leads to the loss of function of GmNNL1, enabling bradyrhizobia to successfully nodulate soybeans through the root hair infection route and enhancing nitrogen fixation. Our findings provide important insights into the coevolution of soybean-bradyrhizobia compatibility and offer a way to design new legume-rhizobia interactions for efficient symbiotic nitrogen fixation.


Assuntos
Bradyrhizobium/metabolismo , Proteínas de Plantas/fisiologia , Raízes de Plantas/microbiologia , Soja/fisiologia , Simbiose/fisiologia , Bradyrhizobium/fisiologia , Estudo de Associação Genômica Ampla , Haplótipos/genética , Fixação de Nitrogênio , Proteínas de Plantas/genética , Raízes de Plantas/fisiologia , Polimorfismo de Nucleotídeo Único/genética , Nódulos Radiculares de Plantas/microbiologia , Nódulos Radiculares de Plantas/fisiologia , Soja/genética , Soja/microbiologia , Sequenciamento Completo do Genoma
13.
Lett Appl Microbiol ; 72(5): 570-577, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33474743

RESUMO

Effect of rhizobial inoculation and nitrate application on the content of bioactive compounds in legume plants is an interesting aspect for interactions among microbes, plants and chemical fertilizers, as well as for cultivated practice of legumes. In this study, nitrate (0, 5 and 20 mmol l-1 ) and Bradyrhizobium arachidis strain CCBAU 051107T were applied, individually or in combination, to the root rhizosphere of the medicinal legume Sophora flavescens Aiton (SFA). Then the plant growth, nodulation and active ingredients including (oxy)matrine of SFA were determined and compared. Rhizobial inoculation alone significantly increased the numbers and fresh weight of root nodules. Nodulation was significantly inhibited due to nitrate (5 and 20 mmol l-1 ). Only oxymatrine was detected in the control plants without rhizobial inoculation and nitrate supplement, while both oxymatrine and matrine were synthesized in plants treated with inoculation of B. arachidis or supplied with nitrate. The content of oxymatrine was the highest in plants inoculated solely with rhizobia and was not significantly altered by additional application of nitrate. Combinations of B. arachidis inoculation and different concentrations of nitrate did not significantly change the concentrations of (oxy)matrine in the plant. In conclusion, sole rhizobial inoculation was the best approach to increase the contents of key active ingredients oxymatrine and matrine in the medicinal legume SFA.


Assuntos
Alcaloides/análise , Bradyrhizobium/metabolismo , Nodulação/fisiologia , Raízes de Plantas/microbiologia , Quinolizinas/análise , Fertilizantes/análise , Nitratos/farmacologia , Rizosfera , Sophora/química , Sophora/microbiologia , Simbiose/fisiologia , Verduras
14.
PLoS Negl Trop Dis ; 15(1): e0008267, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33406097

RESUMO

African trypanosomiasis (AT) is a neglected disease of both humans and animals caused by Trypanosoma parasites, which are transmitted by obligate hematophagous tsetse flies (Glossina spp.). Knowledge on tsetse fly vertebrate hosts and the influence of tsetse endosymbionts on trypanosome presence, especially in wildlife-human-livestock interfaces, is limited. We identified tsetse species, their blood-meal sources, and correlations between endosymbionts and trypanosome presence in tsetse flies from the trypanosome-endemic Maasai Mara National Reserve (MMNR) in Kenya. Among 1167 tsetse flies (1136 Glossina pallidipes, 31 Glossina swynnertoni) collected from 10 sampling sites, 28 (2.4%) were positive by PCR for trypanosome DNA, most (17/28) being of Trypanosoma vivax species. Blood-meal analyses based on high-resolution melting analysis of vertebrate cytochrome c oxidase 1 and cytochrome b gene PCR products (n = 354) identified humans as the most common vertebrate host (37%), followed by hippopotamus (29.1%), African buffalo (26.3%), elephant (3.39%), and giraffe (0.84%). Flies positive for trypanosome DNA had fed on hippopotamus and buffalo. Tsetse flies were more likely to be positive for trypanosomes if they had the Sodalis glossinidius endosymbiont (P = 0.0002). These findings point to complex interactions of tsetse flies with trypanosomes, endosymbionts, and diverse vertebrate hosts in wildlife ecosystems such as in the MMNR, which should be considered in control programs. These interactions may contribute to the maintenance of tsetse populations and/or persistent circulation of African trypanosomes. Although the African buffalo is a key reservoir of AT, the higher proportion of hippopotamus blood-meals in flies with trypanosome DNA indicates that other wildlife species may be important in AT transmission. No trypanosomes associated with human disease were identified, but the high proportion of human blood-meals identified are indicative of human African trypanosomiasis risk. Our results add to existing data suggesting that Sodalis endosymbionts are associated with increased trypanosome presence in tsetse flies.


Assuntos
Animais Selvagens/parasitologia , Insetos Vetores/parasitologia , Gado/parasitologia , Simbiose/fisiologia , Trypanosoma/fisiologia , Moscas Tsé-Tsé/parasitologia , Animais , Artiodáctilos/parasitologia , Sangue , Búfalos/parasitologia , Ecossistema , Elefantes/parasitologia , Enterobacteriaceae , Humanos , Quênia , Reação em Cadeia da Polimerase , Trypanosoma/genética , Trypanosoma vivax , Tripanossomíase Africana/parasitologia
15.
Nat Commun ; 12(1): 676, 2021 01 29.
Artigo em Inglês | MEDLINE | ID: mdl-33514729

RESUMO

Across the evolutionary history of insects, the shift from nitrogen-rich carnivore/omnivore diets to nitrogen-poor herbivorous diets was made possible through symbiosis with microbes. The herbivorous turtle ants Cephalotes possess a conserved gut microbiome which enriches the nutrient composition by recycling nitrogen-rich metabolic waste to increase the production of amino acids. This enrichment is assumed to benefit the host, but we do not know to what extent. To gain insights into nitrogen assimilation in the ant cuticle we use gut bacterial manipulation, 15N isotopic enrichment, isotope-ratio mass spectrometry, and 15N nuclear magnetic resonance spectroscopy to demonstrate that gut bacteria contribute to the formation of proteins, catecholamine cross-linkers, and chitin in the cuticle. This study identifies the cuticular components which are nitrogen-enriched by gut bacteria, highlighting the role of symbionts in insect evolution, and provides a framework for understanding the nitrogen flow from nutrients through bacteria into the insect cuticle.


Assuntos
Exoesqueleto/crescimento & desenvolvimento , Formigas/crescimento & desenvolvimento , Microbioma Gastrointestinal/fisiologia , Herbivoria/fisiologia , Simbiose/fisiologia , Aminoácidos/metabolismo , Animais , Formigas/metabolismo , Formigas/microbiologia , Quitina/biossíntese , Proteínas de Insetos/biossíntese , Nitrogênio/metabolismo
16.
Proc Natl Acad Sci U S A ; 118(5)2021 02 02.
Artigo em Inglês | MEDLINE | ID: mdl-33500354

RESUMO

Recurrent mass bleaching events are pushing coral reefs worldwide to the brink of ecological collapse. While the symptoms and consequences of this breakdown of the coral-algal symbiosis have been extensively characterized, our understanding of the underlying causes remains incomplete. Here, we investigated the nutrient fluxes and the physiological as well as molecular responses of the widespread coral Stylophora pistillata to heat stress prior to the onset of bleaching to identify processes involved in the breakdown of the coral-algal symbiosis. We show that altered nutrient cycling during heat stress is a primary driver of the functional breakdown of the symbiosis. Heat stress increased the metabolic energy demand of the coral host, which was compensated by the catabolic degradation of amino acids. The resulting shift from net uptake to release of ammonium by the coral holobiont subsequently promoted the growth of algal symbionts and retention of photosynthates. Together, these processes form a feedback loop that will gradually lead to the decoupling of carbon translocation from the symbiont to the host. Energy limitation and altered symbiotic nutrient cycling are thus key factors in the early heat stress response, directly contributing to the breakdown of the coral-algal symbiosis. Interpreting the stability of the coral holobiont in light of its metabolic interactions provides a missing link in our understanding of the environmental drivers of bleaching and may ultimately help uncover fundamental processes underpinning the functioning of endosymbioses in general.


Assuntos
Antozoários/fisiologia , Resposta ao Choque Térmico/fisiologia , Nutrientes , Simbiose/fisiologia , Aminoácidos/metabolismo , Compostos de Amônio/metabolismo , Animais , Antozoários/genética , Carbono/metabolismo , Regulação da Expressão Gênica , Modelos Biológicos , Nitrogênio/metabolismo , Estresse Oxidativo , Fotossíntese
17.
Nat Rev Microbiol ; 19(4): 241-255, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33093662

RESUMO

In a striking display of trans-kingdom symbiosis, gut bacteria cooperate with their animal hosts to regulate the development and function of the immune, metabolic and nervous systems through dynamic bidirectional communication along the 'gut-brain axis'. These processes may affect human health, as certain animal behaviours appear to correlate with the composition of gut bacteria, and disruptions in microbial communities have been implicated in several neurological disorders. Most insights about host-microbiota interactions come from animal models, which represent crucial tools for studying the various pathways linking the gut and the brain. However, there are complexities and manifest limitations inherent in translating complex human disease to reductionist animal models. In this Review, we discuss emerging and exciting evidence of intricate and crucial connections between the gut microbiota and the brain involving multiple biological systems, and possible contributions by the gut microbiota to neurological disorders. Continued advances from this frontier of biomedicine may lead to tangible impacts on human health.


Assuntos
Encefalopatias/microbiologia , Encefalopatias/patologia , Microbioma Gastrointestinal/fisiologia , Interações entre Hospedeiro e Microrganismos/fisiologia , Animais , Bactérias/classificação , Bactérias/isolamento & purificação , Encéfalo/microbiologia , Encéfalo/patologia , Humanos , Modelos Animais , Simbiose/fisiologia
18.
Proc Natl Acad Sci U S A ; 117(50): 31979-31986, 2020 12 15.
Artigo em Inglês | MEDLINE | ID: mdl-33257562

RESUMO

Obligate symbioses involving intracellular bacteria have transformed eukaryotic life, from providing aerobic respiration and photosynthesis to enabling colonization of previously inaccessible niches, such as feeding on xylem and phloem, and surviving in deep-sea hydrothermal vents. A major challenge in the study of obligate symbioses is to understand how they arise. Because the best studied obligate symbioses are ancient, it is especially challenging to identify early or intermediate stages. Here we report the discovery of a nascent obligate symbiosis in Howardula aoronymphium, a well-studied nematode parasite of Drosophila flies. We have found that H aoronymphium and its sister species harbor a maternally inherited intracellular bacterial symbiont. We never find the symbiont in nematode-free flies, and virtually all nematodes in the field and the laboratory are infected. Treating nematodes with antibiotics causes a severe reduction in fly infection success. The association is recent, as more distantly related insect-parasitic tylenchid nematodes do not host these endosymbionts. We also report that the Howardula nematode symbiont is a member of a widespread monophyletic group of invertebrate host-associated microbes that has independently given rise to at least four obligate symbioses, one in nematodes and three in insects, and that is sister to Pectobacterium, a lineage of plant pathogenic bacteria. Comparative genomic analysis of this group, which we name Candidatus Symbiopectobacterium, shows signatures of genome erosion characteristic of early stages of symbiosis, with the Howardula symbiont's genome containing over a thousand predicted pseudogenes, comprising a third of its genome.


Assuntos
Drosophila/parasitologia , Enterobacteriaceae/fisiologia , Rabditídios/fisiologia , Simbiose/fisiologia , Animais , Drosophila/microbiologia , Enterobacteriaceae/isolamento & purificação , Genoma Bacteriano/genética , Genômica , Pectobacterium/genética , Filogenia , Pseudogenes/genética , Rabditídios/microbiologia
19.
Nat Commun ; 11(1): 6097, 2020 12 08.
Artigo em Inglês | MEDLINE | ID: mdl-33293528

RESUMO

Prospects for coral persistence through increasingly frequent and extended heatwaves seem bleak. Coral recovery from bleaching is only known to occur after temperatures return to normal, and mitigation of local stressors does not appear to augment coral survival. Capitalizing on a natural experiment in the equatorial Pacific, we track individual coral colonies at sites spanning a gradient of local anthropogenic disturbance through a tropical heatwave of unprecedented duration. Unexpectedly, some corals survived the event by recovering from bleaching while still at elevated temperatures. These corals initially had heat-sensitive algal symbiont communities, endured bleaching, and then recovered through proliferation of heat-tolerant symbionts. This pathway to survival only occurred in the absence of strong local stressors. In contrast, corals in highly disturbed areas were already dominated by heat-tolerant symbionts, and despite initially resisting bleaching, these corals had no survival advantage in one species and 3.3 times lower survival in the other. These unanticipated connections between disturbance, coral symbioses and heat stress resilience reveal multiple pathways to coral survival through future prolonged heatwaves.


Assuntos
Antozoários/fisiologia , Dinoflagelados/fisiologia , Simbiose/fisiologia , Termotolerância/fisiologia , Clima Tropical/efeitos adversos , Animais , Antozoários/microbiologia , Recifes de Corais , Resposta ao Choque Térmico
20.
Proc Biol Sci ; 287(1940): 20201860, 2020 12 09.
Artigo em Inglês | MEDLINE | ID: mdl-33290681

RESUMO

Mutualistic symbioses are common, especially in nutrient-poor environments where an association between hosts and symbionts can allow the symbiotic partners to persist and collectively out-compete non-symbiotic species. Usually these mutualisms are built on an intimate transfer of energy and nutrients (e.g. carbon and nitrogen) between host and symbiont. However, resource availability is not consistent, and the benefit of the symbiotic association can depend on the availability of resources to mutualists. We manipulated the diets of two temperate sea anemone species in the genus Anthopleura in the field and recorded the responses of sea anemones and algal symbionts in the family Symbiodiniaceae to our treatments. Algal symbiont density, symbiont volume and photosynthetic efficiency of symbionts responded to changes in sea anemone diet, but the responses depended on the species of sea anemone. We suggest that temperate sea anemones and their symbionts can respond to changes in anemone diet, modifying the balance between heterotrophy and autotrophy in the symbiosis. Our data support the hypothesis that symbionts are upregulated or downregulated based on food availability, allowing for a flexible nutritional strategy based on external resources.


Assuntos
Meio Ambiente , Microalgas/fisiologia , Anêmonas-do-Mar/fisiologia , Simbiose/fisiologia , Animais , Dieta , Fotossíntese
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