Viewport Size Code:
Login | Create New Account
picture

  MENU

About | Classical Genetics | Timelines | What's New | What's Hot

About | Classical Genetics | Timelines | What's New | What's Hot

icon

Bibliography Options Menu

icon
QUERY RUN:
HITS:
PAGE OPTIONS:
Hide Abstracts   |   Hide Additional Links
NOTE:
Long bibliographies are displayed in blocks of 100 citations at a time. At the end of each block there is an option to load the next block.

Bibliography on: Symbiosis

The Electronic Scholarly Publishing Project: Providing world-wide, free access to classic scientific papers and other scholarly materials, since 1993.

More About:  ESP | OUR CONTENT | THIS WEBSITE | WHAT'S NEW | WHAT'S HOT

ESP: PubMed Auto Bibliography 18 Sep 2020 at 01:51 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: 2020-09-17

Vilcinskas A, Schwabe M, Brinkrolf K, et al (2020)

Larvae of the Clothing Moth Tineola bisselliella Maintain Gut Bacteria that Secrete Enzyme Cocktails to Facilitate the Digestion of Keratin.

Microorganisms, 8(9): pii:microorganisms8091415.

The evolutionary success of insects is promoted by their association with beneficial microbes that enable the utilization of unusual diets. The synanthropic clothing moth Tineola bisselliella provides an intriguing example of this phenomenon. The caterpillars of this species have adapted to feed on keratin-rich diets such as feathers and wool, which cannot be digested by most other animals and are resistant to common digestive enzymes. Inspired by the hypothesis that this ability may be conferred by symbiotic microbes, we utilized a simple assay to detect keratinase activity and a method to screen gut bacteria for candidate enzymes, which were isolated from feather-fed larvae. The isolation of DNA from keratin-degrading bacterial strains followed by de novo genome sequencing resulted in the identification of a novel bacterial strain related to Bacillus sp. FDAARGOS_235. Genome annotation identified 20 genes with keratinase domains. Proteomic analysis of the culture supernatant from this gut bacterium grown in non-nutrient buffer supplemented with feathers revealed several candidate enzymes potentially responsible for keratin degradation, including a thiol-disulfide oxidoreductase and multiple proteases. Our results suggest that the unusual diet of T. bisselliella larvae promotes their association with keratinolytic microorganisms and that the ability of larvae to feed on keratin can at least partially be attributed to bacteria that produce a cocktail of keratin-degrading enzymes.

RevDate: 2020-09-17
CmpDate: 2020-09-17

Agarwal K, Robinson LS, Aggarwal S, et al (2020)

Glycan cross-feeding supports mutualism between Fusobacterium and the vaginal microbiota.

PLoS biology, 18(8):e3000788.

Women with bacterial vaginosis (BV), an imbalance of the vaginal microbiome, are more likely to be colonized by potential pathogens such as Fusobacterium nucleatum, a bacterium linked with intrauterine infection and preterm birth. However, the conditions and mechanisms supporting pathogen colonization during vaginal dysbiosis remain obscure. We demonstrate that sialidase activity, a diagnostic feature of BV, promoted F. nucleatum foraging and growth on mammalian sialoglycans, a nutrient resource that was otherwise inaccessible because of the lack of endogenous F. nucleatum sialidase. In mice with sialidase-producing vaginal microbiotas, mutant F. nucleatum unable to consume sialic acids was impaired in vaginal colonization. These experiments in mice also led to the discovery that F. nucleatum may also "give back" to the community by reinforcing sialidase activity, a biochemical feature of human dysbiosis. Using human vaginal bacterial communities, we show that F. nucleatum supported robust outgrowth of Gardnerella vaginalis, a major sialidase producer and one of the most abundant organisms in BV. These results illustrate that mutually beneficial relationships between vaginal bacteria support pathogen colonization and may help maintain features of dysbiosis. These findings challenge the simplistic dogma that the mere absence of "healthy" lactobacilli is the sole mechanism that creates a permissive environment for pathogens during vaginal dysbiosis. Given the ubiquity of F. nucleatum in the human mouth, these studies also suggest a possible mechanism underlying links between vaginal dysbiosis and oral sex.

RevDate: 2020-09-17
CmpDate: 2020-09-17

Peralta JM, Travaglia CN, Romero-Puertas MC, et al (2020)

Unraveling the impact of arsenic on the redox response of peanut plants inoculated with two different Bradyrhizobium sp. strains.

Chemosphere, 259:127410.

Arsenic (As) can be present naturally in groundwater from peanut fields, constituting a serious problem, as roots can accumulate and mobilize the metalloid to their edible parts. Understanding the redox changes in the legume exposed to As may help to detect potential risks to human health and recognize tolerance mechanisms. Thirty-days old peanut plants inoculated with Bradyrhizobium sp. strains (SEMIA6144 or C-145) were exposed to a realistic arsenate concentration, in order to unravel the redox response and characterize the oxidative stress indexes. Thus, root anatomy, reactive oxygen species detection by fluorescence microscopy and, ROS histochemical staining along with the NADPH oxidase activity were analyzed. Besides, photosynthetic pigments and damage to lipids and proteins were determined as oxidative stress indicators. Results showed that at 3 μM AsV, the cross-section areas of peanut roots were augmented; NADPH oxidase activity was significantly increased and O2˙¯and H2O2 accumulated in leaves and roots. Likewise, an increase in the lipid peroxidation and protein carbonyls was also observed throughout the plant regardless the inoculated strain, while chlorophylls and carotenes were increased only in those inoculated with Bradyrhizobium sp. C-145. Interestingly, the oxidative burst, mainly induced by the NADPH oxidase activity, and the consequent oxidative stress was strain-dependent and organ-differential. Additionally, As modifies the root anatomy, acting as a possibly first defense mechanism against the metalloid entry. All these findings allowed us to conclude that the redox response of peanut is conditioned by the rhizobial strain, which contributes to the importance of effectively formulating bioinoculants for this crop.

RevDate: 2020-09-17
CmpDate: 2020-09-17

Zhang JQ, Zhou T, Xiao CH, et al (2020)

[Technical evaluation and principle analysis of simulative habitat cultivation of Dendrobium nobile].

Zhongguo Zhong yao za zhi = Zhongguo zhongyao zazhi = China journal of Chinese materia medica, 45(9):2042-2045.

The technique of "simulative habitat cultivation" is to preserve the quality of traditional Chinese medicine by simulating the original habitat and site environment of wild Chinese medicine resources. Dendrobium nobile is the most representative variety of traditional Chinese medicine which reflects the coordinated development of medicinal material production and ecological environment. In this paper, the main technical points of the simulated cultivation model of D. nobile were summarized as follows: rapid propagation of seedling tissue technology to ensure the genetic stability of provenance; line card+fermented cow manure+live moss method to improve the survival rate; epiphytic stone cultivation to improve the quality of medicinal materials; and the integration of mycorrhizal fungi to improve the quality stability of medicinal materials. On the basis of summarizing the ecological benefits, economical and social benefits generated by the application of the technology, the paper systematically analyzes the principle of the technology for the cultivation of D. nobile to promote the excellent quality, the light, gas, heat and fertilizer resources of the undergrowth niche are in line with the wild site environment of D. nobile. The rich and complex soil microbial community in the forest laid the foundation for the species diversity needed for the growth of D. nobile.The stress effect on the growth of D. nobile resulted in the accumulation of secondary metabolites. The symbiotic relationship between the symbiotic fungi such as bryophytes and D. nobile promotes the synthesis of plant secondary metabolites. The high quality D. nobile was produced efficiently by improving and optimizing the cultivation techniques.

RevDate: 2020-09-17
CmpDate: 2020-09-17

Becerra JE, Rodríguez-Díaz J, Gozalbo-Rovira R, et al (2020)

Unique Microbial Catabolic Pathway for the Human Core N-Glycan Constituent Fucosyl-α-1,6-N-Acetylglucosamine-Asparagine.

mBio, 11(1):.

The survival of commensal bacteria in the human gut partially depends on their ability to metabolize host-derived molecules. The use of the glycosidic moiety of N-glycoproteins by bacteria has been reported, but the role of N-glycopeptides or glycoamino acids as the substrates for bacterial growth has not been evaluated. We have identified in Lactobacillus casei strain BL23 a gene cluster (alf-2) involved in the catabolism of the glycoamino acid fucosyl-α-1,6-N-GlcNAc-Asn (6'FN-Asn), a constituent of the core-fucosylated structures of mammalian N-glycoproteins. The cluster consists of the genes alfHC, encoding a major facilitator superfamily (MFS) permease and the α-l-fucosidase AlfC, and the divergently oriented asdA (aspartate 4-decarboxylase), alfR2 (transcriptional regulator), pepV (peptidase), asnA2 (glycosyl-asparaginase), and sugK (sugar kinase) genes. Knockout mutants showed that alfH, alfC, asdA, asnA2, and sugK are necessary for efficient 6'FN-Asn utilization. The alf-2 genes are induced by 6'FN-Asn, but not by its glycan moiety, via the AlfR2 regulator. The constitutive expression of alf-2 genes in an alfR2 strain allowed the metabolism of a variety of 6'-fucosyl-glycans. However, GlcNAc-Asn did not support growth in this mutant background, indicating that the presence of a 6'-fucose moiety is crucial for substrate transport via AlfH. Within bacteria, 6'FN-Asn is defucosylated by AlfC, generating GlcNAc-Asn. This glycoamino acid is processed by the glycosylasparaginase AsnA2. GlcNAc-Asn hydrolysis generates aspartate and GlcNAc, which is used as a fermentable source by L.casei These data establish the existence in a commensal bacterial species of an exclusive metabolic pathway likely to scavenge human milk and mucosal fucosylated N-glycopeptides in the gastrointestinal tract.IMPORTANCE The gastrointestinal tract accommodates more than 1014 microorganisms that have an enormous impact on human health. The mechanisms enabling commensal bacteria and administered probiotics to colonize the gut remain largely unknown. The ability to utilize host-derived carbon and energy resources available at the mucosal surfaces may provide these bacteria with a competitive advantage in the gut. Here, we have identified in the commensal species Lactobacillus casei a novel metabolic pathway for the utilization of the glycoamino acid fucosyl-α-1,6-N-GlcNAc-Asn, which is present in the core-fucosylated N-glycoproteins from mammalians. These results give insight into the molecular interactions between the host and commensal/probiotic bacteria and may help to devise new strategies to restore gut microbiota homeostasis in diseases associated with dysbiotic microbiota.

RevDate: 2020-09-17
CmpDate: 2020-09-17

Martin H C, Ibáñez R, Nothias LF, et al (2019)

Viscosin-like lipopeptides from frog skin bacteria inhibit Aspergillus fumigatus and Batrachochytrium dendrobatidis detected by imaging mass spectrometry and molecular networking.

Scientific reports, 9(1):3019.

Amphibian populations worldwide have declined and in some cases become extinct due to chytridiomycosis, a pandemic disease caused by the fungus Batrachochytrium dendrobatidis; however, some species have survived these fungal epidemics. Previous studies have suggested that the resistance of these species is due to the presence of cutaneous bacteria producing antifungal metabolites. As our understanding of these metabolites is still limited, we assessed the potential of such compounds against human-relevant fungi such as Aspergillus. In this work we isolated 201 bacterial strains from fifteen samples belonging to seven frog species collected in the highlands of Panama and tested them against Aspergillus fumigatus. Among the 29 bacterial isolates that exhibited antifungal activity, Pseudomonas cichorii showed the greatest inhibition. To visualize the distribution of compounds and identify them in the inhibition zone produced by P. cichorii, we employed MALDI imaging mass spectrometry (MALDI IMS) and MS/MS molecular networking. We identified viscosin and massetolides A, F, G and H in the inhibition zone. Furthermore, viscosin was isolated and evaluated in vitro against A. fumigatus and B. dendrobatidis showing MIC values of 62.50 µg/mL and 31.25 µg/mL, respectively. This is the first report of cyclic depsipeptides with antifungal activity isolated from frog cutaneous bacteria.

RevDate: 2020-09-16

He C, Liu Y, Ye S, et al (2020)

Changes of intestinal microflora of breast cancer in premenopausal women.

European journal of clinical microbiology & infectious diseases : official publication of the European Society of Clinical Microbiology pii:10.1007/s10096-020-04036-x [Epub ahead of print].

Breast cancer is one of the most common malignant tumors in women. More than half of breast cancer patients are not menopausal at the time of diagnosis. The occurrence and development of premenopausal breast cancer are affected by many factors. Intestinal flora, especially SCFA-producing bacteria, participates in the development of various tumors, and there is a lack of in-depth research in premenopausal breast cancer patients. We used 16S rRNA gene sequencing, targeted metabolomics, and cell culture methods to analyze the changes in the intestinal flora and metabolites of premenopausal breast cancer patients. In addition, we treated breast cancer cells with significantly altered propionate and butyrate in vitro to examine their effects on cell activity. This study followed STROBE guidelines. We found that compared with healthy premenopausal women, the composition and symbiosis of intestinal flora in patients with premenopausal breast cancer changed significantly. The abundance of short-chain fatty acid (SCFA)-producing bacteria was significantly reduced, and the key SCFA-producing enzymes were also significantly reduced. Pediococcus and Desulfovibrio could distinguish premenopausal breast cancer patients from normal premenopausal women. The related propionate and butyrate had a certain ability to inhibit breast cancer cell viability in vitro. As SCFA-producing bacteria, Pediococcus and Desulfovibrio showed potential reference value for the diagnosis of premenopausal breast cancer. The ability of propionate and butyrate to inhibit breast cancer cell lines in vitro suggests that the relevant SCFA receptor may be a new target for the treatment of premenopausal breast cancer.

RevDate: 2020-09-16

Herrera M, Klein SG, Campana S, et al (2020)

Temperature transcends partner specificity in the symbiosis establishment of a cnidarian.

The ISME journal pii:10.1038/s41396-020-00768-y [Epub ahead of print].

Coral reef research has predominantly focused on the effect of temperature on the breakdown of coral-dinoflagellate symbioses. However, less is known about how increasing temperature affects the establishment of new coral-dinoflagellate associations. Inter-partner specificity and environment-dependent colonization are two constraints proposed to limit the acquisition of more heat tolerant symbionts. Here, we investigated the symbiotic dynamics of various photosymbionts in different host genotypes under "optimal" and elevated temperature conditions. To do this, we inoculated symbiont-free polyps of the sea anemone Exaiptasia pallida originating from Hawaii (H2), North Carolina (CC7), and the Red Sea (RS) with the same mixture of native symbiont strains (Breviolum minutum, Symbiodinium linucheae, S. microadriaticum, and a Breviolum type from the Red Sea) at 25 and 32 °C, and assessed their ITS2 composition, colonization rates, and PSII photochemical efficiency (Fv/Fm). Symbiont communities across thermal conditions differed significantly for all hosts, suggesting that temperature rather than partner specificity had a stronger effect on symbiosis establishment. Overall, we detected higher abundances of more heat resistant Symbiodiniaceae types in the 32 °C treatments. Our data further showed that PSII photophysiology under elevated temperature improved with thermal pre-exposure (i.e., higher Fv/Fm), yet, this effect depended on host genotype and was influenced by active feeding as photochemical efficiency dropped in response to food deprivation. These findings highlight the role of temperature and partner fidelity in the establishment and performance of symbiosis and demonstrate the importance of heterotrophy for symbiotic cnidarians to endure and recover from stress.

RevDate: 2020-09-16

Ibarra-Juarez LA, Burton MAJ, Biedermann PHW, et al (2020)

Evidence for Succession and Putative Metabolic Roles of Fungi and Bacteria in the Farming Mutualism of the Ambrosia Beetle Xyleborus affinis.

mSystems, 5(5): pii:5/5/e00541-20.

The bacterial and fungal community involved in ambrosia beetle fungiculture remains poorly studied compared to the famous fungus-farming ants and termites. Here we studied microbial community dynamics of laboratory nests, adults, and brood during the life cycle of the sugarcane shot hole borer, Xyleborus affinis We identified a total of 40 fungal and 428 bacterial operational taxonomic units (OTUs), from which only five fungi (a Raffaelea fungus and four ascomycete yeasts) and four bacterial genera (Stenotrophomonas, Enterobacter, Burkholderia, and Ochrobactrum) can be considered the core community playing the most relevant symbiotic role. Both the fungal and bacterial populations varied significantly during the beetle's life cycle. While the ascomycete yeasts were the main colonizers of the gallery early on, the Raffaelea and other filamentous fungi appeared after day 10, at the time when larval hatching happened. Regarding bacteria, Stenotrophomonas and Enterobacter dominated overall but decreased in foundresses and brood with age. Finally, inferred analyses of the putative metabolic capabilities of the bacterial microbiome revealed that they are involved in (i) degradation of fungal and plant polymers, (ii) fixation of atmospheric nitrogen, and (iii) essential amino acid, cofactor, and vitamin provisioning. Overall, our results suggest that yeasts and bacteria are more strongly involved in supporting the beetle-fungus farming symbiosis than previously thought.IMPORTANCE Ambrosia beetles farm their own food fungi within tunnel systems in wood and are among the three insect lineages performing agriculture (the others are fungus-farming ants and termites). In ambrosia beetles, primary ambrosia fungus cultivars have been regarded essential, whereas other microbes have been more or less ignored. Our KEGG analyses suggest so far unknown roles of yeasts and bacterial symbionts, by preparing the tunnel walls for the primary ambrosia fungi. This preparation includes enzymatic degradation of wood, essential amino acid production, and nitrogen fixation. The latter is especially exciting because if it turns out to be present in vivo in ambrosia beetles, all farming animals (including humans) are dependent on atmospheric nitrogen fertilization of their crops. As previous internal transcribed spacer (ITS) metabarcoding approaches failed on covering the primary ambrosia fungi, our 18S metabarcoding approach can also serve as a template for future studies on the ambrosia beetle-fungus symbiosis.

RevDate: 2020-09-16

Francoeur CB, Khadempour L, Moreira-Soto RD, et al (2020)

Bacteria Contribute to Plant Secondary Compound Degradation in a Generalist Herbivore System.

mBio, 11(5): pii:mBio.02146-20.

Herbivores must overcome a variety of plant defenses, including coping with plant secondary compounds (PSCs). To help detoxify these defensive chemicals, several insect herbivores are known to harbor gut microbiota with the metabolic capacity to degrade PSCs. Leaf-cutter ants are generalist herbivores, obtaining sustenance from specialized fungus gardens that act as external digestive systems and which degrade the diverse collection of plants foraged by the ants. There is in vitro evidence that certain PSCs harm Leucoagaricus gongylophorus, the fungal cultivar of leaf-cutter ants, suggesting a role for the Proteobacteria-dominant bacterial community present within fungus gardens. In this study, we investigated the ability of symbiotic bacteria present within fungus gardens of leaf-cutter ants to degrade PSCs. We cultured fungus garden bacteria, sequenced the genomes of 42 isolates, and identified genes involved in PSC degradation, including genes encoding cytochrome P450 enzymes and genes in geraniol, cumate, cinnamate, and α-pinene/limonene degradation pathways. Using metatranscriptomic analysis, we showed that some of these degradation genes are expressed in situ Most of the bacterial isolates grew unhindered in the presence of PSCs and, using gas chromatography-mass spectrometry (GC-MS), we determined that isolates from the genera Bacillus, Burkholderia, Enterobacter, Klebsiella, and Pseudomonas degrade α-pinene, β-caryophyllene, or linalool. Using a headspace sampler, we show that subcolonies of fungus gardens reduced α-pinene and linalool over a 36-h period, while L. gongylophorus strains alone reduced only linalool. Overall, our results reveal that the bacterial communities in fungus gardens play a pivotal role in alleviating the effect of PSCs on the leaf-cutter ant system.IMPORTANCE Leaf-cutter ants are dominant neotropical herbivores capable of deriving energy from a wide range of plant substrates. The success of leaf-cutter ants is largely due to their external gut, composed of key microbial symbionts, specifically, the fungal mutualist L. gongylophorus and a consistent bacterial community. Both symbionts are known to have critical roles in extracting energy from plant material, yet comparatively little is known about their roles in the detoxification of plant secondary compounds. In this study, we assessed if the bacterial communities associated with leaf-cutter ant fungus gardens can degrade harmful plant chemicals. We identify plant secondary compound detoxification in leaf-cutter ant gardens as a process that depends on the degradative potential of both the bacterial community and L. gongylophorus Our findings suggest that the fungus garden and its associated microbial community influence the generalist foraging abilities of the ants, underscoring the importance of microbial symbionts in plant substrate suitability for herbivores.

RevDate: 2020-09-16

Kovaleva O, Podlesnaya P, Rashidova M, et al (2020)

Lung Microbiome Differentially Impacts Survival of Patients with Non-Small Cell Lung Cancer Depending on Tumor Stroma Phenotype.

Biomedicines, 8(9): pii:biomedicines8090349.

The link between a lung tumor and the lung microbiome is a largely unexplored issue. To investigate the relationship between a lung microbiome and the phenotype of an inflammatory stromal infiltrate, we studied a cohort of 89 patients with non-small cell lung cancer. The microbiome was analyzed in tumor and adjacent normal tissue by 16S rRNA amplicon sequencing. Characterization of the tumor stroma was done using immunohistochemistry. We demonstrated that the bacterial load was higher in adjacent normal tissue than in a tumor (p = 0.0325) with similar patterns of taxonomic structure and alpha diversity. Lung adenocarcinomas did not differ in their alpha diversity from squamous cell carcinomas, although the content of Gram-positive bacteria increased significantly in the adenocarcinoma group (p = 0.0419). An analysis of an inflammatory infiltrate of tumor stroma showed a correlation of CD68, iNOS and FOXP3 with a histological type of tumor. For the first time we showed that high bacterial load in the tumor combined with increased iNOS expression is a favorable prognostic factor (HR = 0.1824; p = 0.0123), while high bacterial load combined with the increased number of FOXP3+ cells is a marker of poor prognosis (HR = 4.651; p = 0.0116). Thus, we established that bacterial load of the tumor has an opposite prognostic value depending on the status of local antitumor immunity.

RevDate: 2020-09-15

Wanke A, Malisic M, Wawra S, et al (2020)

Unraveling the sugar code: the role of microbial extracellular glycans in plant-microbe interactions.

Journal of experimental botany pii:5905709 [Epub ahead of print].

To defend against microbial invaders but also to establish symbiotic programs, plants need to detect the presence of microbes through the perception of molecular signatures characteristic of a whole class of microbes. Among these molecular signatures, extracellular glycans represent a structurally complex and diverse group of biomolecules that has a pivotal role in the molecular dialogue between plants and microbes. Secreted glycans and glycoconjugates like symbiotic lipochitooligosaccharides or immunosuppressive cyclic β-glucans act as microbial messengers that prepare the ground for host colonization. On the other hand, microbial cell-surface glycans are important indicators of microbial presence. They are conserved structures normally exposed and thus accessible for plant hydrolytic enzymes and cell-surface receptor proteins. While the immunogenic potential of bacterial cell-surface glycoconjugates such as lipopolysaccharides and peptidoglycan has been intensively studied in the past years, perception of cell-surface glycans from filamentous microbes such as fungi or oomycetes is still largely unexplored. To date, only few studies have focused on the role of fungal-derived cell-surface glycans other than chitin, highlighting a knowledge gap that needs to be addressed. The objective of this review is to give an overview on the biological functions and perception of microbial extracellular glycans, primarily focusing on their recognition and their contribution to plant-microbe interactions.

RevDate: 2020-09-16
CmpDate: 2020-09-15

Levy O, Fernandes de Barros Marangoni L, I C Benichou J, et al (2020)

Artificial light at night (ALAN) alters the physiology and biochemistry of symbiotic reef building corals.

Environmental pollution (Barking, Essex : 1987), 266(Pt 2):114987.

Artificial Light at Night (ALAN), which is the alteration of natural light levels as the result of anthropogenic light sources, has been acknowledged as an important factor that alters the functioning of marine ecosystems. Using LEDs light to mimic ALAN, we studied the effect on the physiology (symbiont and chlorophyll contents, photosynthesis, respiration, pigment profile, skeletal growth, and oxidative stress responses) of two scleractinian coral species originating from the Red Sea. ALAN induced the photoinhibition of symbiont photosynthesis, as well as an overproduction of reactive oxygen species (ROS) and an increase in oxidative damage to lipids in both coral species. The extent of the deleterious effects of ALAN on the symbiotic association and coral physiology was aligned with the severity of the oxidative stress condition experienced by the corals. The coral species Sylophora pistillata, which experienced a more severe oxidative stress condition than the other species tested, Turbinaria reniformis, also showed a more pronounced bleaching (loss of symbionts and chlorophyll content), enhanced photoinhibition and decreased photosynthetic rates. Findings of the present study further our knowledge on the biochemical mechanisms underpinning the deleterious impacts of ALAN on scleractinian corals, ultimately shedding light on the emerging threat of ALAN on coral reef ecology. Further, considering that global warming and light pollution will increase in the next few decades, future studies should be taken to elucidate the potential synergetic effects of ALAN and global climate change stressors.

RevDate: 2020-09-15
CmpDate: 2020-09-15

Wang X, Zhu X, Bi Y, et al (2020)

Dynamics of microbial community and changes of metabolites during production of type Ι sourdough steamed bread made by retarded sponge-dough method.

Food chemistry, 330:127316.

Dynamics of microbial community and changes of metabolites during production of type Ι sourdough steamed bread made by retarded sponge-dough method (SSB) were studied. Lactobacillus sanfranciscensis and Lactobacillus pontis were the dominant bacterial species. Particularly, relative abundances of Lactobacillus sanfranciscensis were significantly higher than that of other sub-dominant bacterial species. The dominant fungal species were Saccharomyces cerevisiae and Kazachstania humilis, and the latter was the most predominant. A stable bacterial and fungal consortia was established in sponge dough retarded from 12 to 24 h and main dough proofed from 30 to 60 min. Metabolism preference for maltose of Lactobacillus sanfranciscensis favoured a mutualistic association with maltose-negative Kazachstania humilis, and hence contributing to their competitiveness and dominance. Volatile compounds became more abundant with much more esters as sponge retarding time extended. Probably, the accumulation of organic acids and ethanol contributed mostly to formation of ethyl esters in sponge dough during retarding.

RevDate: 2020-09-16
CmpDate: 2020-09-16

Gwida M, Awad A, El-Ashker M, et al (2020)

Microarray-based detection of resistance and virulence factors in commensal Escherichia coli from livestock and farmers in Egypt.

Veterinary microbiology, 240:108539.

The objective of our study was to provide a molecular analysis using DNA-microarray based assays of commensal E. coli populations from apparently healthy livestock and their attendants to assess the virulence potential as well as multidrug resistance (MDR) genotypes. We randomly collected 132 fecal samples from seemingly healthy smallholder´s food producing animals [buffalo (n = 32) and cattle (n = 50)] as well as from contacting farmers (n = 50). Bacterial isolation and identification were performed using standard protocols, while E. coli isolates were characterized using a DNA microarray system targeting 60 different virulence and 47 antibiotic resistance genes of clinical importance and allowing assignment to most common H and O types. From the fecal samples examined, 47 E. coli isolates were obtained. The array predicted serotypes for 14 out of the 47 E. coli isolates. Six E. coli isolates were identified as STEC since Shiga toxin genes were detected. In summary, 36 different virulence genes were identified; of which, hemL, lpfA and iss were most prevalent. Thirty-four E. coli isolates were found to carry at least one antimicrobial resistance gene. Of these, 20 did exhibit genes allowing strain classification as MDR. More than half of the isolates contained antimicrobial resistance genes associated with beta lactam resistance 27/47 (57.5 %). The 13 remaining isolates did not contain any resistance gene tested with the array. Our study demonstrated the presence of antimicrobial resistance genes and virulence genotypes among commensal E. coli of human and animal sources.

RevDate: 2020-09-15
CmpDate: 2020-09-15

Brunel C, Beifen Y, Pouteau R, et al (2020)

Responses of Rhizospheric Microbial Communities of Native and Alien Plant Species to Cuscuta Parasitism.

Microbial ecology, 79(3):617-630.

Parasitic plants have major impacts on host fitness. In the case of species of the holoparasitic Cuscuta genus, these impacts were shown to be particularly strong in some invasive alien plants, which has raised interest in the underlying mechanism. We hypothesized that Cuscuta parasitization may exert strong influence in shaping the diversity patterns in the host rhizosphere microbiome and that this may vary between native (coevolved) and alien (non-coevolved) plants. Here, we report on a field study exploring the effect of parasitization by Cuscuta australis on the rhizosphere microbiota (16S and ITS rDNA) of four plant species sharing and three plant species not sharing the parasite's native range. Despite a predominant role of the host species in shaping the rhizosphere microbiota, the role of host origin and of parasitization still appeared important in structuring microbial communities and their associated functions. Bacterial communities were more strongly influenced than fungi by the native range of the host plant, while fungi were slightly more affected than bacteria by parasitization. About 7% of bacterial phylotypes and 11% of fungal phylotypes were sensitive to Cuscuta parasitization. Parasitization also reduced the abundance of arbuscular mycorrhizal fungi by ca. 18% and of several genes related to plant growth promoting functions (e.g., nitrogen metabolism and quorum sensing). Both fungi and bacteria differentially responded to host parasitization depending on host origin, and the extent of these shifts suggests that they may have more dramatic consequences for alien than for native plants.

RevDate: 2020-09-15
CmpDate: 2020-09-15

Li F, Li P, Hua H, et al (2020)

Diversity, Tissue Localization, and Infection Pattern of Bacterial Symbionts of the White-Backed Planthopper, Sogatella furcifera (Hemiptera: Delphacidae).

Microbial ecology, 79(3):720-730.

The white-backed planthopper (WBPH), Sogatella furcifera (Horváth), is a destructive pest of rice. Bacterial symbionts play an important role in insect hosts, especially hemipteran hosts. This study was designed to examine the bacterial symbionts of the WBPH using 16S rDNA high-throughput sequencing. A total of 63 and 177 operational taxonomic units (OTUs) were identified in females and males of three WBPH populations, respectively. These OTUs included bacteria of 75 genera from 11 phyla, where Wolbachia, Cardinium, and Asaia were the dominant genera, accounting for over 97.99% of all the symbiotic bacteria. Fluorescence in situ hybridization detected Wolbachia, Cardinium, and Asaia in the salivary glands, guts, testes, and eggs of the WBPH, indicating the potential for both horizontal and vertical transmission. Moreover, the infection pattern of the three dominant bacterial symbionts was detected in six WBPH populations. The frequencies of Wolbachia infection of females and Cardinium infection of both sexes were over 96.7%. Wolbachia infection of males ranged between 46.7 and 63.3%, which was significantly lower than that observed for females. Asaia infection of both sexes varied substantially among the populations. These results indicate that the complex host-symbiotic bacteria interaction is influenced by host sex and geographical origin and potentially by the transmission modes of the symbionts.

RevDate: 2020-09-16
CmpDate: 2020-09-16

Jones AG, Mason CJ, Felton GW, et al (2019)

Host plant and population source drive diversity of microbial gut communities in two polyphagous insects.

Scientific reports, 9(1):2792.

Symbioses between insects and microbes are ubiquitous, but vary greatly in terms of function, transmission mechanism, and location in the insect. Lepidoptera (butterflies and moths) are one of the largest and most economically important insect orders; yet, in many cases, the ecology and functions of their gut microbiomes are unresolved. We used high-throughput sequencing to determine factors that influence gut microbiomes of field-collected fall armyworm (Spodoptera frugiperda) and corn earworm (Helicoverpa zea). Fall armyworm midgut bacterial communities differed from those of corn earworm collected from the same host plant species at the same site. However, corn earworm bacterial communities differed between collection sites. Subsequent experiments using fall armyworm evaluating the influence of egg source and diet indicated that that host plant had a greater impact on gut communities. We also observed differences between regurgitant (foregut) and midgut bacterial communities of the same insect host, suggesting differential colonization. Our findings indicate that host plant is a major driver shaping gut microbiota, but differences in insect physiology, gut region, and local factors can also contribute to variation in microbiomes. Additional studies are needed to assess the mechanisms that affect variation in insect microbiomes, as well as the ecological implications of this variability in caterpillars.

RevDate: 2020-09-14

Wang YW, Hess J, Slot JC, et al (2020)

De novo gene birth, horizontal gene transfer and gene duplication as sources of new gene families associated with the origin of symbiosis in Amanita.

Genome biology and evolution pii:5905478 [Epub ahead of print].

By introducing novel capacities and functions, new genes and gene families may play a crucial role in ecological transitions. Mechanisms generating new gene families include de novo gene birth, horizontal gene transfer and neofunctionalization following a duplication event. The ectomycorrhizal (ECM) symbiosis is a ubiquitous mutualism and the association has evolved repeatedly and independently many times among the fungi, but the evolutionary dynamics enabling its emergence remain elusive. We developed a phylogenetic workflow to first understand if gene families unique to ECM Amanita fungi and absent from closely related asymbiotic species are functionally relevant to the symbiosis, and then to systematically infer their origins. We identified 109 gene families unique to ECM Amanita species. Genes belonging to unique gene families are under strong purifying selection and are upregulated during symbiosis, compared to genes of conserved or orphan gene families. The origins of seven of the unique gene families are strongly supported as either de novo gene birth (two gene families), horizontal gene transfer (four), and gene duplication (one). An additional 34 families appear new because of their selective retention within symbiotic species. Among the 109 unique gene families, the most upregulated gene in symbiotic cultures encodes an ACC deaminase, an enzyme capable of downregulating the synthesis of the plant hormone ethylene, a common negative regulator of plant-microbial mutualisms.

RevDate: 2020-09-14

Jensen RE, Cabral C, Enkegaard A, et al (2020)

Influence of the plant interacting entomopathogenic fungus Beauveria bassiana on parasitoid host choice-behavior, development, and plant defense pathways.

PloS one, 15(9):e0238943 pii:PONE-D-20-10979.

Inoculating plants with entomopathogenic fungi may influence plant nutrient uptake and growth, and herbivore performance. Knowledge is limited concerning the effects of this symbiosis on higher trophic levels. We examined how fungal treatment of faba bean seeds with the entomopathogenic fungus Beauveria bassiana influenced the choice-behavior and development of the aphid parasitoid Aphidius colemani. We also sampled plant material for analysis of changes in expression of genes related to plant defense pathways. While parasitoids were compatible with plants inoculated with B. bassiana initially (66 vs. 65% parasitization on inoculated and control plants, respectively; similar development times of parasitoids: 9.2 days), the emergence of adult parasitoids originating from aphids on fungus treated plants was significantly lower (67 vs. 76%, respectively). We also found that the defense response changed, similar to induced systemic resistance, when plants were treated with B. bassiana, similarly to what has been found for other plant symbiotic microorganisms. These novel findings show that although the application of entomopathogenic fungi to plants can alter the plants' defense against herbivores, it may also have an impact on beneficial insects, so their function and use should be evaluated on a case-by-case basis.

RevDate: 2020-09-14

Gonçalves WG, Fernandes KM, Silva APA, et al (2020)

Ultrastructure of the Bacteriocytes in the Midgut of the Carpenter ant Camponotus rufipes: Endosymbiont Control by Autophagy.

Microscopy and microanalysis : the official journal of Microscopy Society of America, Microbeam Analysis Society, Microscopical Society of Canada pii:S1431927620024484 [Epub ahead of print].

The carpenter ant Camponotus rufipes has intracellular bacteria in bacteriocytes scattered in the midgut epithelium, which have different amounts of endosymbionts, according to the developmental stages. However, there are no detailed data about the midgut cells in adult workers. The present work aimed to evaluate the morphology and cellular events that coordinate the abundance of endosymbionts in the midgut cells in C. rufipes workers. The midgut epithelium has digestive cells, bacteriocytes, and cells with intermediate morphology. The latter is similar to bacteriocytes, due to the abundance of endosymbionts, and similar to digestive cells, due to their microvilli. The digestive and intermediate cells are rich in autophagosomes and autolysosomes, both with bacteria debris in the lumen. These findings suggest that midgut cells of C. rufipes control the endosymbiont level by the autophagy pathway.

RevDate: 2020-09-14

Bartlow AW, SJ Agosta (2020)

Phoresy in animals: review and synthesis of a common but understudied mode of dispersal.

Biological reviews of the Cambridge Philosophical Society [Epub ahead of print].

Phoresy is a type of interaction in which one species, the phoront, uses another species, the dispersal host, for transportation to new habitats or resources. Despite being a widespread behaviour, little is known about the ecology and evolution of phoresy. Our goal is to provide a comprehensive review of phoretic dispersal in animals and to bring renewed attention to this subject. We surveyed literature published between 1900 and 2020 to understand the extent of known higher-level taxonomic diversity (phyla, classes, and orders) and functional aspects of animals that use phoretic dispersal. Species dispersing phoretically have been observed in at least 13 animal phyla, 25 classes, and 60 orders. The majority of known phoronts are arthropods (Phylum Euarthropoda) in terrestrial habitats, but phoronts also occur in freshwater and marine environments. Marine phoronts may be severely under-represented in the literature due to the relative difficulty of studying these systems. Phoronts are generally small with low mobility and use habitats or resources that are ephemeral and/or widely dispersed. Many phoronts are also parasites. In general, animals that engage in phoresy use a wide variety of morphological and behavioural traits for locating, attaching to, and detaching from dispersal hosts, but the exact mechanisms behind these activities are largely unknown. In addition to diversity, we discuss the evolution of phoresy including the long-standing idea that it can be a precursor to parasitism and other forms of symbioses. Finally, we suggest several areas of future research to improve our understanding of phoresy and its ecological and evolutionary significance.

RevDate: 2020-09-14

Wei X, Chen J, Zhang C, et al (2020)

Ericoid mycorrhizal fungus enhances microcutting rooting of Rhododendron fortunei and subsequent growth.

Horticulture research, 7:140 pii:361.

Adventitious root (AR) formation is a unique feature of plant reproduction and plays a vital role in crop production as many horticultural and forestry plants are propagated through cuttings. A growing number of reports have shown that microbes, particularly mycorrhizal fungi are able to promote AR formation, but the underlying mechanisms remain largely unclear. This study established an in vitro culture system and investigated AR formation in microcuttings of Rhododendron fortunei Lindl. inoculated with Oidiodendron maius Barron Om19, an ericoid mycorrhizal fungus strain. Hormones and precursors involved in the biosynthesis of indole-3-acetic acid (IAA) in Om19 mycelium were analyzed. Om19 was able to produce a large quantity of tryptophan (Trp) and also indole-3-pyruvate (IPA) and IAA, indicating that IAA biosynthesis in Om19 could be through a Trp-dependent pathway. After inoculation of Om19, ARs were quickly formed in microcuttings. Symbiosis related genes were activated in ARs, and Om19 effectively colonized the roots. YUC3, a key gene in plant biosynthesis of IAA and genes involved in nitrogen (N) uptake and metabolism, phosphorus (P) uptake were highly upregulated. Plants absorbed significantly greater quantity of mineral nutrients, and their growth was substantially enhanced compared to the control plants without Om19 inoculation. A working model for Om19 enhanced AR formation was proposed. The rapid formation of ARs in cuttings could be due in part to the induction of IAA biosynthesized by Om19 and also attributed to Trp catalyzed biosynthesis of IAA in plants. AR formation, in turn, provided Om19 preferred sites for colonization. Our study suggested that in addition to promoting AR formation, Om19 could potentially be used as a new biofertilizer for enhancing production of ericaceous plants, such as blueberry, cranberry, and rhododendron.

RevDate: 2020-09-14

Røy H, Vopel K, Huettel M, et al (2009)

Sulfide assimilation by ectosymbionts of the sessile ciliate, Zoothamnium niveum.

Marine biology, 156(4):669-677.

We investigated the constraints on sulfide uptake by bacterial ectosymbionts on the marine peritrich ciliate Zoothamnium niveum by a combination of experimental and numerical methods. Protists with symbionts were collected on large blocks of mangrove-peat. The blocks were placed in a flow cell with flow adjusted to in situ velocity. The water motion around the colonies was then characterized by particle tracking velocimetry. This shows that the feather-shaped colony of Z. niveum generates a unidirectional flow of seawater through the colony with no recirculation. The source of the feeding current was the free-flowing water although the size of the colonies suggests that they live partly submerged in the diffusive boundary layer. We showed that the filtered volume allows Z. niveum to assimilate sufficient sulfide to sustain the symbiosis at a few micromoles per liter in ambient concentration. Numerical modeling shows that sulfide oxidizing bacteria on the surfaces of Z. niveum can sustain 100-times higher sulfide uptake than bacteria on flat surfaces, such as microbial mats. The study demonstrates that the filter feeding zooids of Z. niveum are preadapted to be prime habitats for sulfide oxidizing bacteria due to Z. niveum's habitat preference and due to the feeding current. Z. niveum is capable of exploiting low concentrations of sulfide in near norm-oxic seawater. This links its otherwise dissimilar habitats and makes it functionally similar to invertebrates with thiotrophic symbionts in filtering organs.

RevDate: 2020-09-14
CmpDate: 2020-09-14

Li H, Limenitakis JP, Greiff V, et al (2020)

Mucosal or systemic microbiota exposures shape the B cell repertoire.

Nature, 584(7820):274-278.

Colonization by the microbiota causes a marked stimulation of B cells and induction of immunoglobulin, but mammals colonized with many taxa have highly complex and individualized immunoglobulin repertoires1,2. Here we use a simplified model of defined transient exposures to different microbial taxa in germ-free mice3 to deconstruct how the microbiota shapes the B cell pool and its functional responsiveness. We followed the development of the immunoglobulin repertoire in B cell populations, as well as single cells by deep sequencing. Microbial exposures at the intestinal mucosa generated oligoclonal responses that differed from those of germ-free mice, and from the diverse repertoire that was generated after intravenous systemic exposure to microbiota. The IgA repertoire-predominantly to cell-surface antigens-did not expand after dose escalation, whereas increased systemic exposure broadened the IgG repertoire to both microbial cytoplasmic and cell-surface antigens. These microbial exposures induced characteristic immunoglobulin heavy-chain repertoires in B cells, mainly at memory and plasma cell stages. Whereas sequential systemic exposure to different microbial taxa diversified the IgG repertoire and facilitated alternative specific responses, sequential mucosal exposure produced limited overlapping repertoires and the attrition of initial IgA binding specificities. This shows a contrast between a flexible response to systemic exposure with the need to avoid fatal sepsis, and a restricted response to mucosal exposure that reflects the generic nature of host-microbial mutualism in the mucosa.

RevDate: 2020-09-14
CmpDate: 2020-09-14

Hewitt KG, Mace WJ, McKenzie CM, et al (2020)

Fungal Alkaloid Occurrence in Endophyte-Infected Perennial Ryegrass during Seedling Establishment.

Journal of chemical ecology, 46(4):410-421.

The symbiotic Epichloë festucae var. lolii endophyte produces alkaloids which can provide its host grass, perennial ryegrass (Lolium perenne L), with a selective advantage in both natural and agricultural managed ecosystems. This study focuses on understanding the alkaloid concentrations that occur in endophyte-infected perennial ryegrass during the early establishment phase. In a glasshouse experiment fungal alkaloid concentrations (peramine, lolitrem B, ergovaline, and epoxy-janthitrems) were measured in perennial ryegrass seedlings infected with E. festucae var. lolii proprietary strains AR1, AR37, NEA2, and NZ common toxic for 69 days after sowing. The endophyte becomes metabolically active, starting alkaloid production, as early as 6 days after sowing. Alkaloid concentrations peaked in 8- to 10- day-old seedlings due to a seedling growth slowdown. This study provides data showing that the loss of insect protection in endophyte-infected seedlings is linked to a reduction in chemical defence after seed-stored, maternally synthesised alkaloids are diluted by seedling dry matter accumulation.

RevDate: 2020-09-14
CmpDate: 2020-09-14

Fuchs B, Kuhnert E, J Krauss (2020)

Contrasting Effects of Grass - Endophyte Chemotypes on a Tri-Trophic Cascade.

Journal of chemical ecology, 46(4):422-429.

Systemic grass-endophytes of the genus Epichloë symbiotically infect the above-ground plant parts of many grass species, where they produce alkaloids in a grass- and endophyte-specific manner that are toxic or deterrent to herbivores. An increasing number of studies show cascading negative effects of endophyte-derived alkaloids that extend to higher trophic levels, harming beneficial insects, including those that control aphid populations. Lacewings are one of the major biological aphid controls, and are especially resistant to insecticides and pollutants, but their susceptibility to endophyte infection in the food chain has never been studied. Our study found variability in aphid population growth depending on the endophyte-grass chemotype, where aphid population growth was lowest on chemotypes known for producing high amounts of loline alkaloids. We also showed that larval and pupal development and mortality of the Common Green Lacewing (Chrysoperla carnea) was, in a non-choice experiment, not affected by endophyte infection in the food chain. This is a first indication that lacewings might be resistant to endophyte-derived alkaloids and could be robust biocontrol agents when applied together with endophyte-infected grass, possibly replacing chemical pesticides.

RevDate: 2020-09-14
CmpDate: 2020-09-14

Spribille T, Tagirdzhanova G, Goyette S, et al (2020)

3D biofilms: in search of the polysaccharides holding together lichen symbioses.

FEMS microbiology letters, 367(5):.

Stable, long-term interactions between fungi and algae or cyanobacteria, collectively known as lichens, have repeatedly evolved complex architectures with little resemblance to their component parts. Lacking any central scaffold, the shapes they assume are casts of secreted polymers that cement cells into place, determine the angle of phototropic exposure and regulate water relations. A growing body of evidence suggests that many lichen extracellular polymer matrices harbor unicellular, non-photosynthesizing organisms (UNPOs) not traditionally recognized as lichen symbionts. Understanding organismal input and uptake in this layer is key to interpreting the role UNPOs play in lichen biology. Here, we review both polysaccharide composition determined from whole, pulverized lichens and UNPOs reported from lichens to date. Most reported polysaccharides are thought to be structural cell wall components. The composition of the extracellular matrix is not definitively known. Several lines of evidence suggest some acidic polysaccharides have evaded detection in routine analysis of neutral sugars and may be involved in the extracellular matrix. UNPOs reported from lichens include diverse bacteria and yeasts for which secreted polysaccharides play important biological roles. We conclude by proposing testable hypotheses on the role that symbiont give-and-take in this layer could play in determining or modifying lichen symbiotic outcomes.

RevDate: 2020-09-14
CmpDate: 2020-09-14

Treanor D, WOH Hughes (2019)

Limited female dispersal predicts the incidence of Wolbachia across ants (Hymenoptera: Formicidae).

Journal of evolutionary biology, 32(10):1163-1170.

The endosymbiotic bacterium Wolbachia is perhaps the greatest panzootic in the history of life on Earth, yet remarkably little is known regarding the factors that determine its incidence across species. One possibility is that Wolbachia more easily invades species with structured populations, due to the increased strength of genetic drift and higher initial frequency of infection. This should enable strains that induce mating incompatibilities to more easily cross the threshold prevalence above which they spread to either fixation or a stable equilibrium infection prevalence. Here, we provide empirical support for this hypothesis by analysing the relationship between female dispersal (as a proxy for population structure) and the incidence of Wolbachia across 250 species of ants. We show that species in which the dispersal of reproductive females is limited are significantly more likely to be infected with Wolbachia than species whose reproductive ecology is consistent with significant dispersal of females, and that this relationship remains after controlling for host phylogeny. We suggest that structured host populations, in this case resulting from limited female dispersal, may be an important feature determining how easily Wolbachia becomes successfully established in a novel host, and thus its occurrence across a wide diversity of invertebrate hosts.

RevDate: 2020-09-12

Okubo N, Tamura-Nakano M, T Watanabe (2020)

Experimental observation of microplastics invading the endoderm of anthozoan polyps.

Marine environmental research, 162:105125 pii:S0141-1136(20)30387-1 [Epub ahead of print].

Coral reefs are being degraded worldwide by land reclamation and environmental factors, such as high seawater temperature, resulting in mass bleaching events. In addition, microplastics disturb the formation of coral-algae symbiotic relationships in primary polyps. In our experiments, we observed this effect in the bleached primary polyp Seriatopora caliendrum that lost its symbiont Symbiodiniaceae as a result of high water temperature. There was a higher incorporation of microspheres into bleached corals than in healthy ones. To understand the interference in symbiosis, we used the sea anemone Exaiptasia (as an anthozoan model organism) and fed it with microspheres. TEM results suggested the incorporation of microspheres and symbionts from the same phagocytosis zones in the mesenterial filament and endocytosis by the cells. In the tentacles, microspheres were in the same cell layer as the symbionts. These results suggest that microplastics occupy the spaces inhabited by Symbiodiniaceae, thereby hindering their symbiotic association.

RevDate: 2020-09-12

Budnick JA, Sheehan LM, Ginder MJ, et al (2020)

A central role for the transcriptional regulator VtlR in small RNA-mediated gene regulation in Agrobacterium tumefaciens.

Scientific reports, 10(1):14968 pii:10.1038/s41598-020-72117-0.

LysR-type transcriptional regulators (LTTRs) are the most common type of transcriptional regulators in prokaryotes and function by altering gene expression in response to environmental stimuli. In the class Alphaproteobacteria, a conserved LTTR named VtlR is critical to the establishment of host-microbe interactions. In the mammalian pathogen Brucella abortus, VtlR is required for full virulence in a mouse model of infection, and VtlR activates the expression of abcR2, which encodes a small regulatory RNA (sRNA). In the plant symbiont Sinorhizobium meliloti, the ortholog of VtlR, named LsrB, is involved in the symbiosis of the bacterium with alfalfa. Agrobacterium tumefaciens is a close relative of both B. abortus and S. meliloti, and this bacterium is the causative agent of crown gall disease in plants. In the present study, we demonstrate that VtlR is involved in the ability of A. tumefaciens to grow appropriately in artificial medium, and an A. tumefaciens vtlR deletion strain is defective in motility, biofilm formation, and tumorigenesis of potato discs. RNA-sequencing analyses revealed that more than 250 genes are dysregulated in the ∆vtlR strain, and importantly, VtlR directly controls the expression of three sRNAs in A. tumefaciens. Taken together, these data support a model in which VtlR indirectly regulates hundreds of genes via manipulation of sRNA pathways in A. tumefaciens, and moreover, while the VtlR/LsrB protein is present and structurally conserved in many members of the Alphaproteobacteria, the VtlR/LsrB regulatory circuitry has diverged in order to accommodate the unique environmental niche of each organism.

RevDate: 2020-09-12

Martinson VG (2020)

Rediscovering a Forgotten System of Symbiosis: Historical Perspective and Future Potential.

Genes, 11(9): pii:genes11091063.

While the majority of symbiosis research is focused on bacteria, microbial eukaryotes play important roles in the microbiota and as pathogens, especially the incredibly diverse Fungi kingdom. The recent emergence of widespread pathogens in wildlife (bats, amphibians, snakes) and multidrug-resistant opportunists in human populations (Candida auris) has highlighted the importance of better understanding animal-fungus interactions. Regardless of their prominence there are few animal-fungus symbiosis models, but modern technological advances are allowing researchers to utilize novel organisms and systems. Here, I review a forgotten system of animal-fungus interactions: the beetle-fungus symbioses of Drugstore and Cigarette beetles with their symbiont Symbiotaphrina. As pioneering systems for the study of mutualistic symbioses, they were heavily researched between 1920 and 1970, but have received only sporadic attention in the past 40 years. Several features make them unique research organisms, including (1) the symbiont is both extracellular and intracellular during the life cycle of the host, and (2) both beetle and fungus can be cultured in isolation. Specifically, fungal symbionts intracellularly infect cells in the larval and adult beetle gut, while accessory glands in adult females harbor extracellular fungi. In this way, research on the microbiota, pathogenesis/infection, and mutualism can be performed. Furthermore, these beetles are economically important stored-product pests found worldwide. In addition to providing a historical perspective of the research undertaken and an overview of beetle biology and their symbiosis with Symbiotaphrina, I performed two analyses on publicly available genomic data. First, in a preliminary comparative genomic analysis of the fungal symbionts, I found striking differences in the pathways for the biosynthesis of two B vitamins important for the host beetle, thiamine and biotin. Second, I estimated the most recent common ancestor for Drugstore and Cigarette beetles at 8.8-13.5 Mya using sequence divergence (CO1 gene). Together, these analyses demonstrate that modern methods and data (genomics, transcriptomes, etc.) have great potential to transform these beetle-fungus systems into model systems again.

RevDate: 2020-09-12

Pereira AC, Ramos B, Reis AC, et al (2020)

Non-Tuberculous Mycobacteria: Molecular and Physiological Bases of Virulence and Adaptation to Ecological Niches.

Microorganisms, 8(9): pii:microorganisms8091380.

Non-tuberculous mycobacteria (NTM) are paradigmatic colonizers of the total environment, circulating at the interfaces of the atmosphere, lithosphere, hydrosphere, biosphere, and anthroposphere. Their striking adaptive ecology on the interconnection of multiple spheres results from the combination of several biological features related to their exclusive hydrophobic and lipid-rich impermeable cell wall, transcriptional regulation signatures, biofilm phenotype, and symbiosis with protozoa. This unique blend of traits is reviewed in this work, with highlights to the prodigious plasticity and persistence hallmarks of NTM in a wide diversity of environments, from extreme natural milieus to microniches in the human body. Knowledge on the taxonomy, evolution, and functional diversity of NTM is updated, as well as the molecular and physiological bases for environmental adaptation, tolerance to xenobiotics, and infection biology in the human and non-human host. The complex interplay between individual, species-specific and ecological niche traits contributing to NTM resilience across ecosystems are also explored. This work hinges current understandings of NTM, approaching their biology and heterogeneity from several angles and reinforcing the complexity of these microorganisms often associated with a multiplicity of diseases, including pulmonary, soft-tissue, or milliary. In addition to emphasizing the cornerstones of knowledge involving these bacteria, we identify research gaps that need to be addressed, stressing out the need for decision-makers to recognize NTM infection as a public health issue that has to be tackled, especially when considering an increasingly susceptible elderly and immunocompromised population in developed countries, as well as in low- or middle-income countries, where NTM infections are still highly misdiagnosed and neglected.

RevDate: 2020-09-11

Pan XX, Yuan MQ, Xiang SY, et al (2020)

The symbioses of endophytic fungi shaped the metabolic profiles in grape leaves of different varieties.

PloS one, 15(9):e0238734 pii:PONE-D-20-13785.

Endophytic fungi produce many novel bioactive metabolites that are directly used as drugs or that function as the precursor structures of other chemicals. The metabolic shaping of endophytes on grape cells was reported previously. However, there are no reports on the interactions and metabolic impact of endophyte symbiosis on in vitro vine leaves, which may be examined under well-controlled conditions that are more representative of the natural situation of endophytes within grapevines. The present study used an in vitro leaf method to establish endophyte symbiosis of grapevines and analyze the effects on the metabolic profiles of grape leaves from two different cultivars, 'Rose honey' (RH) and 'Cabernet sauvignon' (CS). The effects of endophytic fungi on the metabolic profiles of grape leaves exhibited host selectivity and fungal strain specificity. Most of the endophytic fungal strains introduced novel metabolites into the two varieties of grape leaves according to the contents of the detected metabolites and composition of metabolites. Strains RH49 and MDR36, with high or moderate symbiosis rates, triggered an increased response in terms of the detected metabolites, and the strains MDR1 and MDR33 suppressed the detected metabolites in CS and RH leaves despite having strong or moderate symbiosis ability. However, the strain RH12 significantly induced the production of novel metabolites in RH leaves due to its high symbiosis ability and suppression of metabolites in CS leaves.

RevDate: 2020-09-11

Košuthová A, Bergsten J, Westberg M, et al (2020)

Species delimitation in the cyanolichen genus Rostania.

BMC evolutionary biology, 20(1):115 pii:10.1186/s12862-020-01681-w.

BACKGROUND: In this study, we investigate species limits in the cyanobacterial lichen genus Rostania (Collemataceae, Peltigerales, Lecanoromycetes). Four molecular markers (mtSSU rDNA, β-tubulin, MCM7, RPB2) were sequenced and analysed with two coalescent-based species delimitation methods: the Generalized Mixed Yule Coalescent model (GMYC) and a Bayesian species delimitation method (BPP) using a multispecies coalescence model (MSC), the latter with or without an a priori defined guide tree.

RESULTS: Species delimitation analyses indicate the presence of eight strongly supported candidate species. Conclusive correlation between morphological/ecological characters and genetic delimitation could be found for six of these. Of the two additional candidate species, one is represented by a single sterile specimen and the other currently lacks morphological or ecological supporting evidence.

CONCLUSIONS: We conclude that Rostania includes a minimum of six species: R. ceranisca, R. multipunctata, R. occultata 1, R. occultata 2, R. occultata 3, and R. occultata 4,5,6. Three distinct Nostoc morphotypes occur in Rostania, and there is substantial correlation between these morphotypes and Rostania thallus morphology.

RevDate: 2020-09-11
CmpDate: 2020-09-11

Rush TA, Puech-Pagès V, Bascaules A, et al (2020)

Lipo-chitooligosaccharides as regulatory signals of fungal growth and development.

Nature communications, 11(1):3897.

Lipo-chitooligosaccharides (LCOs) are signaling molecules produced by rhizobial bacteria that trigger the nodulation process in legumes, and by some fungi that also establish symbiotic relationships with plants, notably the arbuscular and ecto mycorrhizal fungi. Here, we show that many other fungi also produce LCOs. We tested 59 species representing most fungal phyla, and found that 53 species produce LCOs that can be detected by functional assays and/or by mass spectroscopy. LCO treatment affects spore germination, branching of hyphae, pseudohyphal growth, and transcription in non-symbiotic fungi from the Ascomycete and Basidiomycete phyla. Our findings suggest that LCO production is common among fungi, and LCOs may function as signals regulating fungal growth and development.

RevDate: 2020-09-11
CmpDate: 2020-09-11

Koumandou VL, Papageorgiou L, Tsaniras SC, et al (2020)

Microbiome Hijacking Towards an Integrative Pest Management Pipeline.

Advances in experimental medicine and biology, 1195:21-32.

Pesticides are necessary to fight agricultural pests, yet they are often nonspecific, and their widespread use is a hazard to the environment and human health. The genomic era allows for new approaches to specifically target agricultural pests, based on analysis of their genome and their microbiome. We present such an approach, to combat Bactrocera oleae, a widespread pest whose impact is devastating on olive production. To date, there is no specific pesticide to control it. Herein, we propose a novel strategy to manage this pest via identifying novel pharmacological targets on the genome of its obligate endosymbiotic bacterium Candidatus Erwinia dacicola. Three genes were selected as pharmacological targets. The 3D models of the Helicase, Polymerase, and Protease-C gene products were designed and subsequently optimized by means of molecular dynamics simulations. Successively, a series of structure-based pharmacophore models were elucidated in an effort to pave the way for the efficient high-throughput virtual screening of libraries of low molecular weight compounds and thus the discovery of novel modulating agents. Our methodology provides the means to design, test, and identify highly specific pest control substances that minimize the impact of toxic chemicals on health, economy, and the environment.

RevDate: 2020-09-11
CmpDate: 2020-09-11

Hoysted GA, Jacob AS, Kowal J, et al (2019)

Mucoromycotina Fine Root Endophyte Fungi Form Nutritional Mutualisms with Vascular Plants.

Plant physiology, 181(2):565-577.

Fungi and plants have engaged in intimate symbioses that are globally widespread and have driven terrestrial biogeochemical processes since plant terrestrialization >500 million years ago. Recently, hitherto unknown nutritional mutualisms involving ancient lineages of fungi and nonvascular plants have been discovered, although their extent and functional significance in vascular plants remain uncertain. Here, we provide evidence of carbon-for-nitrogen exchange between an early-diverging vascular plant (Lycopodiella inundata) and Mucoromycotina (Endogonales) fine root endophyte fungi. Furthermore, we demonstrate that the same fungal symbionts colonize neighboring nonvascular and flowering plants. These findings fundamentally change our understanding of the physiology, interrelationships, and ecology of underground plant-fungal symbioses in modern terrestrial ecosystems by revealing the nutritional role of Mucoromycotina fungal symbionts in vascular plants.

RevDate: 2020-09-10

Rossbacher S, C Vorburger (2020)

Prior adaptation of parasitoids improves biological control of symbiont-protected pests.

Evolutionary applications, 13(8):1868-1876 pii:EVA12934.

There is increasing demand for sustainable pest management to reduce harmful effects of pesticides on the environment and human health. For pest aphids, biological control with parasitoid wasps provides a welcome alternative, particularly in greenhouses. However, aphids are frequently infected with the heritable bacterial endosymbiont Hamiltonella defensa, which increases resistance to parasitoids and thereby hampers biological control. Using the black bean aphid (Aphis fabae) and its main parasitoid Lysiphlebus fabarum, we tested whether prior adaptation of parasitoids can improve the control of symbiont-protected pests. We had parasitoid lines adapted to two different strains of H. defensa by experimental evolution, as well as parasitoids evolved on H. defensa-free aphids. We compared their ability to control caged aphid populations comprising 60% unprotected and 40% H. defensa-protected aphids, with both H. defensa strains present in the populations. Parasitoids that were not adapted to H. defensa had virtually no effect on aphid population dynamics compared to parasitoid-free controls, but one of the adapted lines and a mixture of both adapted lines controlled aphids successfully, strongly benefitting plant growth. Selection by parasitoids altered aphid population composition in a very specific manner. Aphid populations became dominated by H. defensa-protected aphids in the presence of parasitoids, and each adapted parasitoid line selected for the H. defensa strain it was not adapted to. This study shows, for the first time, that prior adaptation of parasitoids improves biological control of symbiont-protected pests, but the high specificity of parasitoid counter-resistance may represent a challenge for its implementation.

RevDate: 2020-09-10

Sharma A, SH Im (2020)

Special issue on the human microbiome: from symbiosis to therapy.

RevDate: 2020-09-10

Jain SS, Afiq-Rosli L, Feldman B, et al (2020)

Homogenization of Endosymbiont Communities Hosted by Equatorial Corals during the 2016 Mass Bleaching Event.

Microorganisms, 8(9): pii:microorganisms8091370.

Thermal stress drives the bleaching of reef corals, during which the endosymbiotic relationship between Symbiodiniaceae microalgae and the host breaks down. The endosymbiont communities are known to shift in response to environmental disturbances, but how they respond within and between colonies during and following bleaching events remains unclear. In 2016, a major global-scale bleaching event hit countless tropical reefs. Here, we investigate the relative abundances of Cladocopium LaJeunesse & H.J.Jeong, 2018 and Durusdinium LaJeunesse, 2018 within and among Pachyseris speciosa colonies in equatorial Singapore that are known to host both these Symbiodiniaceae clades. Bleached and unbleached tissues from bleaching colonies, as well as healthy colonies, during and following the bleaching event were sampled and analyzed for comparison. The nuclear ribosomal internal transcribed spacer (ITS) regions were separately amplified and quantified using a SYBR Green-based quantitative polymerase chain reaction (qPCR) method and Illumina high-throughput sequencing. We found Cladocopium to be highly abundant relative to Durusdinium. The relative abundance of Durusdinium, known to be thermally tolerant, was highest in post-bleaching healthy colonies, while bleached and unbleached tissues from bleaching colonies as well as tissue from healthy colonies during the event had depressed proportions of Durusdinium. Given the importance of Durusdinium for thermal tolerance and stress response, it is surprising that bleached tissue showed limited change over healthy tissue during the bleaching event. Moreover, colonies were invariably dominated by Cladocopium during bleaching, but a minority of colonies were Durusdinium-dominant during non-bleaching times. The detailed characterization of Symbiodiniaceae in specific colonies during stress and recovery will provide insights into this crucial symbiosis, with implications for their responses during major bleaching events.

RevDate: 2020-09-10
CmpDate: 2020-09-10

Lhee D, Ha JS, Kim S, et al (2019)

Evolutionary dynamics of the chromatophore genome in three photosynthetic Paulinella species.

Scientific reports, 9(1):2560.

The thecate amoeba Paulinella is a valuable model for understanding plastid organellogenesis because this lineage has independently gained plastids (termed chromatophores) of alpha-cyanobacterial provenance. Plastid primary endosymbiosis in Paulinella occurred relatively recently (90-140 million years ago, Mya), whereas the origin of the canonical Archaeplastida plastid occurred >1,500 Mya. Therefore, these two events provide independent perspectives on plastid formation on vastly different timescales. Here we generated the complete chromatophore genome sequence from P. longichromatophora (979,356 bp, GC-content = 38.8%, 915 predicted genes) and P. micropora NZ27 (977,190 bp, GC-content = 39.9%, 911 predicted genes) and compared these data to that from existing chromatophore genomes. Our analysis suggests that when a basal split occurred among photosynthetic Paulinella species ca. 60 Mya, only 35% of the ancestral orthologous gene families from the cyanobacterial endosymbiont remained in chromatophore DNA. Following major gene losses during the early stages of endosymbiosis, this process slowed down significantly, resulting in a conserved gene content across extant taxa. Chromatophore genes faced relaxed selection when compared to homologs in free-living alpha-cyanobacteria, likely reflecting the homogeneous intracellular environment of the Paulinella host. Comparison of nucleotide substitution and insertion/deletion events among different P. micropora strains demonstrates that increases in AT-content and genome reduction are ongoing and dynamic processes in chromatophore evolution.

RevDate: 2020-09-09

Mu X, Zhang S, Han B, et al (2020)

Impacts of water flow on epiphytic microbes and nutrients removal in constructed wetlands dominated by Vallisneria natans with decreasing temperature.

Bioresource technology, 318:124058 pii:S0960-8524(20)31330-4 [Epub ahead of print].

The mechanisms behind water flow on contaminant removal by a submerged macrophyte-biofilm complex in surface flow wetlands remain to be fully elucidated. In this study, water flow (2.02 ~ 2.12 or 4.06 ~ 4.5 L s-1; hydraulic retention time, 7d) significantly enhanced NH4+-N and COD but inhibited TN and TP removal compared to the static ones. No more than 30% of TN and TP were assimilated by V. natans-biofilm complex in wetland system. Water flow remarkably affected alpha-diversity of microbial community in epiphytic biofilm. As revealed by beta-diversity analysis, turnover played greater contribution to the total dissimilarity than nestedness. Network analyses revealed that the microbial interactions including predation, symbiosis and competition in epiphytic biofilms were much more intensive in the Sept.- Oct. than the Nov.-Dec group. Redundancy and Mantel correlation analyses revealed that temperature played a key role in determining microbial community structure, especially for bacteria.

RevDate: 2020-09-09

Singh A, Jadhav S, MR Roopashree (2020)

Factors to Overcoming Barriers Affecting Electronic Medical Record Usage by Physicians.

Indian journal of community medicine : official publication of Indian Association of Preventive & Social Medicine, 45(2):168-171.

Background: Hospitals are adopting electronic medical records (EMRs) in larger numbers; however, the barrier to derive its full utility is the low acceptance by physicians.

Aims and Objectives: This study is done with an objective to identify the factors to overcome the barriers preventing the adoption of EMR by physicians.

Materials and Methods: This study is cross sectional in natures and a self-administered questionnaire is developed based on the Technology Acceptance Model.

Results: The four identified factors are positive attitude toward EMR, reliability, difficulty to use, and adaptability, these factors together, have explained 62.54 percent variance in the data set.

Conclusion: The physician's acceptance for EMRs can be improved by focusing on the identified four factors, which are "positive attitude toward electronic medical records," reliability of electronic medical records," "difficulty level of use," and "adaptability of electronic medical records."

RevDate: 2020-09-09

Ding PH, Yang MX, Wang NN, et al (2020)

Porphyromonas gingivalis-Induced NLRP3 Inflammasome Activation and Its Downstream Interleukin-1β Release Depend on Caspase-4.

Frontiers in microbiology, 11:1881.

Background: Oral commensals contribute to microbe-host symbiosis in periodontal homeostasis, and Porphyromonas gingivalis (P. gingivalis) as the keystone pathogen critically accounts for the shift of symbiosis to dysbiosis and periodontal destruction. Nucleotide-binding oligomerization domain (NOD)-like receptor (NLR) family pyrin domain containing 3 (NLRP3) inflammasome-mediated interleukin-1β (IL-1β) is significantly involved in periodontal diseases, and notably P. gingivalis enables to modulate the induction and expression of NLRP3. Whereas, the exact mechanism by which NLRP3 inflammasome is regulated in response to commensal and pathogenic bacteria remains unclear. Methods: To examine the expression of IL-1β and NLRPs inflammasome in tissues with severe chronic periodontitis, and further investigate how Caspase-4-dependent non-canonical NLRP3 inflammasome pathways functioned during the interactions of Streptococcus mitis (S. mitis) and P. gingivalis with human THP-1 cells. Results: IL-1β and NLRP3, NLRP6, NLRP12, and absent in melanoma 2 (AIM2) inflammasomes are highly expressed in gingival tissues with severe chronic periodontitis. In human THP-1 cells, P. gingivalis activates the synthesis and secretion of IL-1β to higher levels than S. mitis. Importantly, NLRP3-, Caspase-1-, and Caspase-4-siRNA knockdown THP-1 cells treated with P. gingivalis exhibited a lower expression level of IL-1β as compared to the control cells. In addition, silencing of either CASP4 or CASP1 can lead to a concurrent or reciprocal decrease in the expression of the other. Of note, the IL-1β induction is not affected in the S. mitis-treated THP-1 cells with the silence of NLRP3, Caspase-1, and Caspase-4 genes. Conclusion: NLRP3/Caspase-4 and NLRP3/Caspase-1 dependent IL-1β production may crucially contribute to the dysregulated immuno-inflammatory response in periodontal pathogenesis.

RevDate: 2020-09-09

Wheatley RM, Ford BL, Li L, et al (2020)

Lifestyle adaptations of Rhizobium from rhizosphere to symbiosis.

Proceedings of the National Academy of Sciences of the United States of America pii:2009094117 [Epub ahead of print].

By analyzing successive lifestyle stages of a model Rhizobium-legume symbiosis using mariner-based transposon insertion sequencing (INSeq), we have defined the genes required for rhizosphere growth, root colonization, bacterial infection, N2-fixing bacteroids, and release from legume (pea) nodules. While only 27 genes are annotated as nif and fix in Rhizobium leguminosarum, we show 603 genetic regions (593 genes, 5 transfer RNAs, and 5 RNA features) are required for the competitive ability to nodulate pea and fix N2 Of these, 146 are common to rhizosphere growth through to bacteroids. This large number of genes, defined as rhizosphere-progressive, highlights how critical successful competition in the rhizosphere is to subsequent infection and nodulation. As expected, there is also a large group (211) specific for nodule bacteria and bacteroid function. Nodule infection and bacteroid formation require genes for motility, cell envelope restructuring, nodulation signaling, N2 fixation, and metabolic adaptation. Metabolic adaptation includes urea, erythritol and aldehyde metabolism, glycogen synthesis, dicarboxylate metabolism, and glutamine synthesis (GlnII). There are 17 separate lifestyle adaptations specific to rhizosphere growth and 23 to root colonization, distinct from infection and nodule formation. These results dramatically highlight the importance of competition at multiple stages of a Rhizobium-legume symbiosis.

RevDate: 2020-09-09

Hamada M, Satoh N, K Khalturin (2020)

A Reference Genome from the Symbiotic Hydrozoan, Hydra viridissima.

G3 (Bethesda, Md.) pii:g3.120.401411 [Epub ahead of print].

Various Hydra species have been employed as model organisms since the 18th century. Introduction of transgenic and knock-down technologies made them ideal experimental systems for studying cellular and molecular mechanisms involved in regeneration, body-axis formation, senescence, symbiosis, and holobiosis. In order to provide an important reference for genetic studies, the Hydra magnipapillata genome (species name has been changed to H. vulgaris) was sequenced a decade ago (Chapman et al, 2010) and the updated genome assembly, Hydra 2.0, was made available by the National Human Genome Research Institute in 2017. While H. vulgaris belongs to the non-symbiotic brown hydra lineage, the green hydra, Hydra viridissima, harbors algal symbionts and belongs to an early diverging clade that separated from the common ancestor of brown and green hydra lineages at least 100 million years ago (Schwentner and Bosch, 2015; Khalturin et al, 2019). While interspecific interactions between H. viridissima and endosymbiotic unicellular green algae of the genus Chlorella have been a subject of interest for decades, genomic information about green hydras was nonexistent. Here we report a draft 280-Mbp genome assembly for Hydra viridissima strain A99, with a scaffold N50 of 1.1 Mbp. The H. viridissima genome contains an estimated 21,476 protein-coding genes. Comparative analysis of Pfam domains and orthologous proteins highlights characteristic features of H. viridissima, such as diversification of innate immunity genes that are important for host-symbiont interactions. Thus, the H. viridissima assembly provides an important hydrozoan genome reference that will facilitate symbiosis research and better comparisons of metazoan genome architectures.

RevDate: 2020-09-09

Lastovetsky OA, Krasnovsky LD, Qin X, et al (2020)

Molecular Dialogues between Early Divergent Fungi and Bacteria in an Antagonism versus a Mutualism.

mBio, 11(5): pii:mBio.02088-20.

Fungal-bacterial symbioses range from antagonisms to mutualisms and remain one of the least understood interdomain interactions despite their ubiquity as well as ecological and medical importance. To build a predictive conceptual framework for understanding interactions between fungi and bacteria in different types of symbioses, we surveyed fungal and bacterial transcriptional responses in the mutualism between Rhizopus microsporus (Rm) (ATCC 52813, host) and its Mycetohabitans (formerly Burkholderia) endobacteria versus the antagonism between a nonhost Rm (ATCC 11559) and Mycetohabitans isolated from the host, at two time points, before and after partner physical contact. We found that bacteria and fungi sensed each other before contact and altered gene expression patterns accordingly. Mycetohabitans did not discriminate between the host and nonhost and engaged a common set of genes encoding known as well as novel symbiosis factors. In contrast, responses of the host versus nonhost to endobacteria were dramatically different, converging on the altered expression of genes involved in cell wall biosynthesis and reactive oxygen species (ROS) metabolism. On the basis of the observed patterns, we formulated a set of hypotheses describing fungal-bacterial interactions and tested some of them. By conducting ROS measurements, we confirmed that nonhost fungi increased production of ROS in response to endobacteria, whereas host fungi quenched their ROS output, suggesting that ROS metabolism contributes to the nonhost resistance to bacterial infection and the host ability to form a mutualism. Overall, our study offers a testable framework of predictions describing interactions of early divergent Mucoromycotina fungi with bacteria.IMPORTANCE Animals and plants interact with microbes by engaging specific surveillance systems, regulatory networks, and response modules that allow for accommodation of mutualists and defense against antagonists. Antimicrobial defense responses are mediated in both animals and plants by innate immunity systems that owe their functional similarities to convergent evolution. Like animals and plants, fungi interact with bacteria. However, the principles governing these relations are only now being discovered. In a study system of host and nonhost fungi interacting with a bacterium isolated from the host, we found that bacteria used a common gene repertoire to engage both partners. In contrast, fungal responses to bacteria differed dramatically between the host and nonhost. These findings suggest that as in animals and plants, the genetic makeup of the fungus determines whether bacterial partners are perceived as mutualists or antagonists and what specific regulatory networks and response modules are initiated during each encounter.

RevDate: 2020-09-09

Formiga F, FJ Tarazona-Santabalbina (2020)

[Diabetes and COVID-19 in the elderly, harmful symbiosis].

Revista espanola de geriatria y gerontologia pii:S0211-139X(20)30134-7 [Epub ahead of print].

RevDate: 2020-09-09

Scherlach K, C Hertweck (2020)

Chemical Mediators at the Bacterial-Fungal Interface.

Annual review of microbiology, 74:267-290.

Interactions among microbes are key drivers of evolutionary progress and constantly shape ecological niches. Microorganisms rely on chemical communication to interact with each other and surrounding organisms. They synthesize natural products as signaling molecules, antibiotics, or modulators of cellular processes that may be applied in agriculture and medicine. Whereas major insight has been gained into the principles of intraspecies interaction, much less is known about the molecular basis of interspecies interplay. In this review, we summarize recent progress in the understanding of chemically mediated bacterial-fungal interrelations. We discuss pairwise interactions among defined species and systems involving additional organisms as well as complex interactions among microbial communities encountered in the soil or defined as microbiota of higher organisms. Finally, we give examples of how the growing understanding of microbial interactions has contributed to drug discovery and hypothesize what may be future directions in studying and engineering microbiota for agricultural or medicinal purposes.

RevDate: 2020-09-09
CmpDate: 2020-09-09

Kirchhoff T (2020)

The myth of Frederic Clements's mutualistic organicism, or: on the necessity to distinguish different concepts of organicism.

History and philosophy of the life sciences, 42(2):24 pii:10.1007/s40656-020-00317-y.

In the theory and history of ecology, Frederic Clements's theory of plant communities is usually presented as the historical prototype and a paradigmatic example of synecological organicism, characterised by the assumption that ecological communities are functionally integrated units of mutually dependent species. In this paper, I will object to this standard interpretation of Clements's theory. Undoubtedly, Clements compares plant communities with organisms and calls them "complex organisms" and "superorganisms". Further, he can indeed be regarded as a proponent of ecological organicism-provided that one defines ecological organicism as the interpretation of synecological units according to the model of the individual organism. However, Clements's theory does not include the assumption that mutual dependence is a principle of the organisation of plant communities. Rather, he interprets plant communities as top-down control-hierarchical entities, in which subordinate species depend on dominant species-but not the other way around. Therefore, his theory represents what may be called 'control-hierarchical organicism' as against 'mutualistic organicism'. The erroneous attribution to Clements of 'mutualistic organicism' might be due to an unawareness of the existence of different concepts of the organism. This unawareness results in the projection on Clements's theory of a seemingly self-evident mutualistic concept of organism that Clements himself did not use as a basis for his theory of plant communities.

RevDate: 2020-09-09
CmpDate: 2020-09-09

Schaming TD, CS Sutherland (2020)

Landscape- and local-scale habitat influences on occurrence and detection probability of Clark's nutcrackers: Implications for conservation.

PloS one, 15(5):e0233726.

Whitebark pine (Pinus albicaulis), a keystone species and an obligate mutualist of the Clark's nutcracker (Nucifraga columbiana), is rapidly declining throughout its range. Evidence suggests this decline is leading to a downward trend in local nutcracker populations, which would in-turn decrease whitebark pine regeneration. Our objectives were to (1) evaluate temporal variation in nutcracker habitat use as a function of whitebark pine and Douglas-fir (Pseudotsuga menziesii) habitat, at local and landscape scales, (2) develop metrics for predicting when whitebark pine communities require intervention to sustain nutcracker visitation, and (3) test McKinney et al. (2009) and Barringer et al.'s (2012) models predicting nutcracker occurrence. Between 2009 and 2013, we carried out 3,135 audio-visual Clark's nutcracker surveys at 238 random points in the southern Greater Yellowstone Ecosystem. Using Bayesian occupancy models and cross-product model selection, we evaluated the association between nutcracker occurrence and habitat variables during five stages of the nutcracker annual cycle, while accounting for imperfect detection. Nutcracker occurrence was most strongly associated with the presence of cone-bearing whitebark pine trees (rather than cone density) and the area of whitebark pine on the landscape. To promote a high, >75%, probability of occurrence at a site within the study area, we recommend a management plan that achieves a landscape composed of a minimum of 12,500-25,000 ha of cone-bearing whitebark pine habitat within a 32.6 km radius. Additionally, an optimal habitat mosaic includes moderate levels of Douglas-fir habitat. Models currently used to guide whitebark pine management strategies underpredicted nutcracker occurrence in our study area, suggesting these strategies may not be appropriate in the region. We cannot predict how this mutualistic relationship will change as the population density of each species shifts. We therefore suggest conducting periodic surveys to re-evaluate the relationship as the environment changes and management strategies are implemented.

RevDate: 2020-09-09
CmpDate: 2020-09-09

Ganyukova AI, Frolov AO, Malysheva MN, et al (2020)

A novel endosymbiont-containing trypanosomatid Phytomonas borealis sp. n. from the predatory bug Picromerus bidens (Heteroptera: Pentatomidae).

Folia parasitologica, 67:.

Here we describe the new trypanosomatid, Phytomonas borealis sp. n., from the midgut of the spiked shieldbugs, Picromerus bidens (Linnaeus), collected in two locations, Novgorod and Pskov Oblasts of Russia. The phylogenetic analyses, based on the 18S rRNA gene, demonstrated that this flagellate is a sister species to the secondary monoxenous Phytomonas nordicus Frolov et Malysheva, 1993, which was concurrently documented in the same host species in Pskov Oblast. Unlike P. nordicus, which can complete its development (including exit to haemolymph and penetration into salivary glands) in Picromerus bidens, the new species did not form any extraintestinal stages in the host. It also did not produce endomastigotes, indispensable for transmission in other Phytomonas spp. These observations, along with the fact that P. bidens overwinters at the egg stage, led us to the conclusion that the examined infections with P. borealis were non-specific. Strikingly, the flagellates from the Novgorod population contained prokaryotic endosymbionts, whereas the parasites from the second locality were endosymbiont-free. This is a first case documenting presence of intracellular symbiotic bacteria in Phytomonas spp. We suggest that this novel endosymbiotic association arose very recently and did not become obligate yet. Further investigation of P. borealis and its intracellular bacteria may shed light on the origin and early evolution of endosymbiosis in trypanosomatids.

RevDate: 2020-09-09
CmpDate: 2020-09-09

Pandit A, Adholeya A, Cahill D, et al (2020)

Microbial biofilms in nature: unlocking their potential for agricultural applications.

Journal of applied microbiology, 129(2):199-211.

Soil environments are dynamic and the plant rhizosphere harbours a phenomenal diversity of micro-organisms which exchange signals and beneficial nutrients. Bipartite beneficial or symbiotic interactions with host roots, such as mycorrhizae and various bacteria, are relatively well characterized. In addition, a tripartite interaction also exists between plant roots, arbuscular mycorrhizal fungi (AMF) and associated bacteria. Bacterial biofilms exist as a sheet of bacterial cells in association with AMF structures, embedded within a self-produced exopolysaccharide matrix. Such biofilms may play important functional roles within these tripartite interactions. However, the details about such interactions in the rhizosphere and their relevant functional relationships have not been elucidated. This review explores the current understanding of naturally occurring microbial biofilms, and their interaction with biotic surfaces, especially AMF. The possible roles played by bacterial biofilms and the potential for their application for a more productive and sustainable agriculture is discussed in this review.

RevDate: 2020-09-09
CmpDate: 2020-09-09

Nag P, Shriti S, S Das (2020)

Microbiological strategies for enhancing biological nitrogen fixation in nonlegumes.

Journal of applied microbiology, 129(2):186-198.

In an agro-ecosystem, industrially produced nitrogenous fertilizers are the principal sources of nitrogen for plant growth; unfortunately these also serve as the leading sources of pollution. Hence, it becomes imperative to find pollution-free methods of providing nitrogen to crop plants. A diverse group of free-living, plant associative and symbiotic prokaryotes are able to perform biological nitrogen fixation (BNF). BNF is a two component process involving the nitrogen fixing diazotrophs and the host plant. Symbiotic nitrogen fixation is most efficient as it can fix nitrogen inside the nodule formed on the roots of the plant; delivering nitrogen directly to the host. However, most of the important crop plants are nonleguminous and are unable to form symbiotic associations. In this context, the plant associative and endophytic diazotrophs assume importance. BNF in nonlegumes can be encouraged either through the transfer of BNF traits from legumes or by elevating the nitrogen fixing capacity of the associative and endophytic diazotrophs. In this review we discuss mainly the microbiological strategies which may be used in nonleguminous crops for enhancement of BNF.

RevDate: 2020-09-08

Rejili M, Off K, Brachmann A, et al (2020)

Bradyrhizobium hipponense sp. nov., isolated from Lupinus angustifolius growing in the northern region of Tunisia.

International journal of systematic and evolutionary microbiology [Epub ahead of print].

Strain aSej3T was isolated from a root nodule of a Lupinus angustifolius plant growing in Bizerte, Tunisia. 16S rRNA gene analysis placed this strain within the genus Bradyrhizobium. Multilocus sequence analysis (MLSA) including three housekeeping genes (glnII, gyrB and recA) grouped aSej3T together with Bradyrhizobium rifense CTAW71T, Bradyrhizobium cytisi CTAW11T, Bradyrhizobium ganzhouense RITF806T, Bradyrhizobium lupini USDA 3051T and Bradyrhizobium canariense BTA-1T. MLSA with five housekeeping genes (dnaK, glnII, gyrB, recA and rpoB) revealed that this strain shares less than 93.5 % nucleotide identity with other type strains. Genome sequencing and inspection revealed a genome size of 8.83 Mbp with a G+C content of 62.8 mol%. Genome-wide average nucleotide identity and digital DNA-DNA hybridization values were below 87.5 and 36.2 %, respectively, when compared to described Bradyrhizobium species. Strain aSej3T nodulated L. angustifolius plants under axenic conditions and its nodC gene clustered within the genistearum symbiovar. Altogether, the phylogenetic data and the chemotaxonomic characteristics of this strain support that aSej3T represents a new species for which we propose the name Bradyrhizobium hipponense sp. nov. with the type strain aSej3T (=DSM 108913T=LMG 31020T).

RevDate: 2020-09-08

Koch RA, Liu J, Brann M, et al (2020)

Marasmioid rhizomorphs in bird nests: Species diversity, functional specificity, and new species from the tropics.

Mycologia [Epub ahead of print].

In tropical and subtropical rainforests, vegetative fungal rhizomorphs from the Marasmiineae are routinely used as construction material in bird nests. Because rhizomorphs seldom produce mushrooms within nests, the fungal species involved remain largely unknown. In turn, this limitation has prevented us from resolving broader questions such as whether specific fungal species are selected by birds for different functional roles (i.e., attachment, or parasite control). To fill some of these gaps, we collected 74 rhizomorph-containing bird nests from the Neo- and Afrotropics and used nuc rDNA internal transcribed spacer ITS1-5.8S-ITS2 (ITS) sequences to discriminate between rhizomorph-forming species. In total we recovered 25 Marasmiineae species used by birds in nest construction, none of which were shared between the Neotropics and the Afrotropics. We also collected Marasmiineae basidiomes in the vicinity of nests and used ITS sequences to match these sporulating morphs with nest rhizomorphs for nine species. Basidiomes from an additional five species were found fruiting from rhizomorphs incorporated within bird nests. Finally, an additional six species were putatively identified based on publicly available sequence data. Rhizomorphs of five species were found to be utilized almost exclusively as lining material in nests. Lining material comes in direct contact with nestlings and is hypothesized to play a role in parasite control. Rhizomorphs from 10 species were used to attach and anchor nests to substrates; we matched six of those to fruiting litter trap-forming species collected in the understory. Litter traps hold large quantities of fallen litter material, suggesting that birds may preferentially use rhizomorphs that are adapted to bearing heavy loads for nest attachment. Finally, we describe two species of Marasmius-M. neocrinis-equi, sp. nov., and M. nidus-avis, sp. nov.-that are commonly found associated with bird nests and show that rhizomorph production is common across the genus.

RevDate: 2020-09-08
CmpDate: 2020-09-08

Ianiri G, Coelho MA, Ruchti F, et al (2020)

HGT in the human and skin commensal Malassezia: A bacterially derived flavohemoglobin is required for NO resistance and host interaction.

Proceedings of the National Academy of Sciences of the United States of America, 117(27):15884-15894.

The skin of humans and animals is colonized by commensal and pathogenic fungi and bacteria that share this ecological niche and have established microbial interactions. Malassezia are the most abundant fungal skin inhabitant of warm-blooded animals and have been implicated in skin diseases and systemic disorders, including Crohn's disease and pancreatic cancer. Flavohemoglobin is a key enzyme involved in microbial nitrosative stress resistance and nitric oxide degradation. Comparative genomics and phylogenetic analyses within the Malassezia genus revealed that flavohemoglobin-encoding genes were acquired through independent horizontal gene transfer events from different donor bacteria that are part of the mammalian microbiome. Through targeted gene deletion and functional complementation in Malassezia sympodialis, we demonstrated that bacterially derived flavohemoglobins are cytoplasmic proteins required for nitric oxide detoxification and nitrosative stress resistance under aerobic conditions. RNA-sequencing analysis revealed that endogenous accumulation of nitric oxide resulted in up-regulation of genes involved in stress response and down-regulation of the MalaS7 allergen-encoding genes. Solution of the high-resolution X-ray crystal structure of Malassezia flavohemoglobin revealed features conserved with both bacterial and fungal flavohemoglobins. In vivo pathogenesis is independent of Malassezia flavohemoglobin. Lastly, we identified an additional 30 genus- and species-specific horizontal gene transfer candidates that might have contributed to the evolution of this genus as the most common inhabitants of animal skin.

RevDate: 2020-09-08
CmpDate: 2020-09-08

Velivelli SLS, Czymmek KJ, Li H, et al (2020)

Antifungal symbiotic peptide NCR044 exhibits unique structure and multifaceted mechanisms of action that confer plant protection.

Proceedings of the National Academy of Sciences of the United States of America, 117(27):16043-16054.

In the indeterminate nodules of a model legume Medicago truncatula, ∼700 nodule-specific cysteine-rich (NCR) peptides with conserved cysteine signature are expressed. NCR peptides are highly diverse in sequence, and some of these cationic peptides exhibit antimicrobial activity in vitro and in vivo. However, there is a lack of knowledge regarding their structural architecture, antifungal activity, and modes of action against plant fungal pathogens. Here, the three-dimensional NMR structure of the 36-amino acid NCR044 peptide was solved. This unique structure was largely disordered and highly dynamic with one four-residue α-helix and one three-residue antiparallel β-sheet stabilized by two disulfide bonds. NCR044 peptide also exhibited potent fungicidal activity against multiple plant fungal pathogens, including Botrytis cinerea and three Fusarium spp. It inhibited germination in quiescent spores of B. cinerea In germlings, it breached the fungal plasma membrane and induced reactive oxygen species. It bound to multiple bioactive phosphoinositides in vitro. Time-lapse confocal and superresolution microscopy revealed strong fungal cell wall binding, penetration of the cell membrane at discrete foci, followed by gradual loss of turgor, subsequent accumulation in the cytoplasm, and elevated levels in nucleoli of germlings. Spray-applied NCR044 significantly reduced gray mold disease symptoms caused by the fungal pathogen B. cinerea in tomato and tobacco plants, and postharvest products. Our work illustrates the antifungal activity of a structurally unique NCR peptide against plant fungal pathogens and paves the way for future development of this class of peptides as a spray-on fungistat/fungicide.

RevDate: 2020-09-08
CmpDate: 2020-09-08

Silva R, Filgueiras L, Santos B, et al (2020)

Gluconacetobacter diazotrophicus Changes The Molecular Mechanisms of Root Development in Oryza sativa L. Growing Under Water Stress.

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

BACKGROUND: Inoculation with Gluconacetobacter diazotrophicus has shown to influence root development in red rice plants, and more recently, the induced systemic tolerance (IST) response to drought was also demonstrated. The goal of this study was to evaluate the inoculation effect of G. diazotrophicus strain Pal5 on the amelioration of drought stress and root development in red rice (Oryza sativa L.).

METHODS: The experimental treatments consist of red rice plants inoculated with and without strain Pal5 in presence and absence of water restriction. Physiological, biochemical, and molecular analyses of plant roots were carried out, along with measurements of growth and biochemical components.

RESULTS: The plants showed a positive response to the bacterial inoculation, with root growth promotion and induction of tolerance to drought. An increase in the root area and higher levels of osmoprotectant solutes were observed in roots. Bacterial inoculation increased the drought tolerance and positively regulated certain root development genes against the water deficit in plants.

CONCLUSION: G. diazotrophicus Pal5 strain inoculation favored red rice plants by promoting various root growth and developmental mechanisms against drought stress, enabling root development and improving biochemical composition.

RevDate: 2020-09-08
CmpDate: 2020-09-08

Strand MR, GR Burke (2020)

Polydnaviruses: Evolution and Function.

Current issues in molecular biology, 34:163-182.

Polydnaviruses (PDVs) were originally viewed as large DNA viruses that are beneficial symbionts of parasitoid wasps. Two groups of PDVs were also recognized: bracoviruses (BVs), which are associated with wasps in the family Braconidae, and ichnoviruses (IVs), which are associated with wasps in the family Ichneumonidae. Results to date indicate that BVs are endogenous virus elements (EVEs) that evolved from an ancient betanudivirus. IVs are also likely EVEs but are unrelated to BVs. BVs and IVs are very unusual relative to most known EVEs because they retain many viral functions that benefit wasps in parasitizing hosts. However, BVs and IVs cannot be considered beneficial symbionts because all components of their genomes are fixed in wasps. Recent studies indicate that other nudiviruses have endogenized in insects. Each exhibits a different functional fate from BVs but shares certain architectural features. We discuss options for classifying BVs and other endogenized nudiviruses. We also discuss future directions.

RevDate: 2020-09-07

Lenhart PA, JA White (2020)

Endosymbionts facilitate rapid evolution in a polyphagous herbivore.

Journal of evolutionary biology [Epub ahead of print].

Maternally transmitted bacterial symbionts can be important mediators of the interactions between insect herbivores and their foodplants. These symbionts are often facultative (present in some host individuals but not others) and can have large effects on their host's phenotype, thus giving rise to heritable variation upon which selection can act. In the cowpea aphid (Aphis craccivora) it has been established that the facultative endosymbiont Arsenophonus improves aphid performance on black locust trees (Robinia pseudoacacia) but not on fava (Vicia faba). Here, we tested whether this fitness differential translated into contemporaneous evolution of aphid populations associated with the different plants. In a laboratory study lasting 16 weeks, we found that the frequency of Arsenophonus-infected individuals significantly increased over time for aphid populations on black locust but declined for aphid populations on fava. By the end of the experiment, Arsenophonus infection was >3× more common on black locust than fava, which is comparable to previously described infection frequencies in natural field populations. Our results clearly demonstrate that aphid populations with mixed facultative symbiont infection status can rapidly evolve in response to the selective environments imposed by different host plants. This selection differential may be a sufficient explanation for the global association between Arsenophonus-infected cowpea aphids and black locust trees, without invoking additional assortative mechanisms. Because the aphid and plant originate from different parts of the world, we further hypothesize that Arsenophonus infection may have acted as a preadaptation that has promoted functional specialisation of infected aphids on a novel host plant.

RevDate: 2020-09-07

Shu H, Luo Z, Peng Z, et al (2020)

The application of CRISPR/Cas9 in hairy roots to explore the functions of AhNFR1 and AhNFR5 genes during peanut nodulation.

BMC plant biology, 20(1):417 pii:10.1186/s12870-020-02614-x.

BACKGROUND: Peanut is an important legume crop growing worldwide. With the published allotetraploid genomes, further functional studies of the genes in peanut are very critical for crop improvement. CRISPR/Cas9 system is emerging as a robust tool for gene functional study and crop improvement, which haven't been extensively utilized in peanut yet. Peanut plant forms root nodules to fix nitrogen through a symbiotic relationship with rhizobia. In model legumes, the response of plants to rhizobia is initiated by Nod factor receptors (NFRs). However, information about the function of NFRs in peanut is still limited. In this study, we applied the CRISPR/Cas9 tool in peanut hairy root transformation system to explore the function of NFR genes.

RESULTS: We firstly identified four AhNFR1 genes and two AhNFR5 genes in cultivated peanut (Tifrunner). The gene expression analysis showed that the two AhNFR1 and two AhNFR5 genes had high expression levels in nodulating (Nod+) line E5 compared with non-nodulating (Nod-) line E4 during the process of nodule formation, suggesting their roles in peanut nodulation. To further explore their functions in peanut nodulation, we applied CRISPR technology to create knock-out mutants of AhNFR1 and AhNFR5 genes using hairy root transformation system. The sequencing of these genes in transgenic hairy roots showed that the selected AhNFR1 and AhNFR5 genes were successfully edited by the CRISPR system, demonstrating its efficacy for targeted mutation in allotetraploid peanut. The mutants with editing in the two AhNFR5 genes showed Nod- phenotype, whereas mutants with editing in the two selected AhNFR1 genes could still form nodules after rhizobia inoculation.

CONCLUSIONS: This study showed that CRISPR-Cas9 could be used in peanut hairy root transformation system for peanut functional genomic studies, specifically on the gene function in roots. By using CRISPR-Cas9 targeting peanut AhNFR genes in hairy root transformation system, we validated the function of AhNFR5 genes in nodule formation in peanut.

RevDate: 2020-09-07
CmpDate: 2020-09-07

Geesink P, Wegner CE, Probst AJ, et al (2020)

Genome-inferred spatio-temporal resolution of an uncultivated Roizmanbacterium reveals its ecological preferences in groundwater.

Environmental microbiology, 22(2):726-737.

Subsurface ecosystems like groundwater harbour diverse microbial communities, including small-sized, putatively symbiotic organisms of the Candidate Phyla Radiation, yet little is known about their ecological preferences and potential microbial partners. Here, we investigated a member of the superphylum Microgenomates (Cand. Roizmanbacterium ADI133) from oligotrophic groundwater using mini-metagenomics and monitored its spatio-temporal distribution using 16S rRNA gene analyses. A Roizmanbacteria-specific quantitative PCR assay allowed us to track its abundance over the course of 1 year within eight groundwater wells along a 5.4 km hillslope transect, where Roizmanbacteria reached maximum relative abundances of 2.3%. In-depth genomic analyses suggested that Cand. Roizmanbacterium ADI133 is a lactic acid fermenter, potentially able to utilize a range of complex carbon substrates, including cellulose. We hypothesize that it attaches to host cells using a trimeric autotransporter adhesin and inhibits their cell wall biosynthesis using a toxin-antitoxin system. Network analyses based on correlating Cand. Roizmanbacterium ADI133 abundances with amplicon sequencing-derived microbial community profiles suggested one potential host organism, classified as a member of the class Thermodesulfovibrionia (Nitrospirae). By providing lactate as an electron donor Cand. Roizmanbacterium ADI133 potentially mediates the transfer of carbon to other microorganisms and thereby is an important connector in the microbial community.

RevDate: 2020-09-05

Garg N, A Cheema (2020)

Relative roles of Arbuscular Mycorrhizae in establishing a correlation between soil properties, carbohydrate utilization and yield in Cicer arietinum L. under As stress.

Ecotoxicology and environmental safety, 207:111196 pii:S0147-6513(20)31035-6 [Epub ahead of print].

Accumulation of As (metalloid) degrades soil by negatively affecting the activities of soil enzymes, which in turn reduce growth and yield of the inhabiting plant. Arbuscular mycorrhizal (AM) symbiosis can impart metalloid tolerance in plants by secreting glomalin-related soil protein (GRSP) which binds with As or inertly adsorb in the extraradical mycelial surface. However, profitable use of AM requires selection of the most efficient combination of host plant and fungal species. The current study, therefore designed to study the efficacy of 3 a.m. fungal species: Rhizoglomus intraradices (Ri), Funneliformis mosseae (Fm) and Claroideoglomus claroideum (Cc) in imparting arsenate As(V) and arsenite As(III) stress tolerance in Cicer arietinum (chickpea) genotypes (G) - relatively metalloid tolerant- HC 3 and sensitive- C 235. Roots were found to be more severly affected as compared to shoots which resulted into a major decline in uptake of nutrients, chlorophyll concentrations and yield with As(III) inducing more toxic effects than As(V). HC 3 established more effective mycorrhizal symbiosis and was able to extract higher nutrients from the soil than C 235. Ri was most beneficial in improving plant biomass, carbohydrate utilization and productivity followed by Fm and Cc which could be due to its capability to initiate highest percent colonization and least metalloid uptake in roots through higher glomalin production in the soil. Moreover, Ri was highly efficient in improving soil enzymes activities-phosphatases (PHAs), β-glucosidase (BGA) and invertase (INV), thereby, imparting metalloid tolerance in chickpea genotypes. The results suggested use of Ri-chickpea symbiosis as a promising strategy for ameliorating As stress in chickpea.

RevDate: 2020-09-05

Li T, Chen X, S Lin (2020)

Physiological and transcriptomic responses to N-deficiency and ammonium: Nitrate shift in Fugacium kawagutii (Symbiodiniaceae).

The Science of the total environment, 753:141906 pii:S0048-9697(20)35435-8 [Epub ahead of print].

Symbiodiniaceae are the source of essential coral symbionts of reef building corals. The growth and density of endosymbiotic Symbiodiniaceae within the coral host is dependent on nutrient availability, yet little is known about how Symbiodiniaceae respond to the dynamics of the nutrients, including switch between different chemical forms and changes in abundance. In this study, we investigated physiological, cytometric, and transcriptomic responses in Fugacium kawagutii to nitrogen (N)-nutrient deficiency and different chemical N forms (nitrate and ammonium) in batch culture conditions. We mainly found that ammonium was consumed faster than nitrate when provided separately, and was preferentially utilized over nitrate when both N compounds were supplied at 1:2, 1:1 and 2:1 molarity ratios. Besides, N-deficiency caused decreases in growth, energy production, antioxidative capacity and investment in photosynthate transport but increased energy consumption. Growing on ammonium produced a similar cell yield as nitrate, but with a reduced investment in nutrient transport and assimilation; yet at high concentrations ammonium exhibited inhibitory effects. These findings together have important implications in N-nutrient regulation of coral symbiosis. In addition, we identified ten highly and stably expressed genes as candidate reference genes, which will be potentially useful for gene expression studies in the future.

RevDate: 2020-09-04

Wall CB, Egan CP, Swift SIO, et al (2020)

Three decades post reforestation has not led to the reassembly of arbuscular mycorrhizal fungal communities associated with remnant primary forests.

Molecular ecology [Epub ahead of print].

The negative effects of deforestation can potentially be ameliorated through ecological restoration. However, reforestation alone may not reassemble the same ecological communities or functions as primary forests. In part, this failure may be owed to forest ecosystems inherently involving complex interactions among guilds of organisms. Plants, which structure forest food webs, rely on intimate associations with symbiotic microbes such as root-inhabiting mycorrhizal fungi. Here, we leverage a large-scale reforestation project on Hawai'i Island underway for over three decades to assess whether arbuscular mycorrhizal (AM) fungal communities have concurrently been restored. The reference ecosystem for this restoration project is a remnant montane native Hawaiian forest that provides critical habitat for endangered birds. We sampled soils from 12 plots within remnant and restored forest patches and characterized AM fungal communities using high throughput Illumina MiSeq DNA sequencing. While some AM fungal community metrics were comparable between remnant and restored forest (e.g., species richness), other key characteristics were not. Specifically, community membership and the identity of AM fungal keystone species differed between the two habitat types, as well as the primary environmental factors influencing community composition. Remnant forest AM fungal communities were strongly associated with soil chemical properties, especially pH, while restored forest communities were influenced by the spatial proximity to remnant forests. We posit that combined, these differences in soil AM fungal communities could be negatively affecting the recruitment of native plant hosts and that future restoration efforts should consider plant-microbe interactions as an important facet of forest health.

RevDate: 2020-09-04

Hugo H, Cristaldo PF, O DeSouza (2020)

Nonaggressive behavior: A strategy employed by an obligate nest invader to avoid conflict with its host species.

Ecology and evolution, 10(16):8741-8754 pii:ECE36572.

In addition to its builders, termite nests are known to house a variety of secondary opportunistic termite species so-called inquilines, but little is known about the mechanisms governing the maintenance of these symbioses. In a single nest, host and inquiline colonies are likely to engage in conflict due to nestmate discrimination, and an intriguing question is how both species cope with each other in the long term. Evasive behaviour has been suggested as one of the mechanisms reducing the frequency of host-inquiline encounters, yet, the confinement imposed by the nests' physical boundaries suggests that cohabiting species would eventually come across each other. Under these circumstances, it is plausible that inquilines would be required to behave accordingly to secure their housing. Here, we show that once inevitably exposed to hosts individuals, inquilines exhibit nonthreatening behaviours, displaying hence a less threatening profile and preventing conflict escalation with their hosts. By exploring the behavioural dynamics of the encounter between both cohabitants, we find empirical evidence for a lack of aggressiveness by inquilines towards their hosts. Such a nonaggressive behaviour, somewhat uncommon among termites, is characterised by evasive manoeuvres that include reversing direction, bypassing and a defensive mechanism using defecation to repel the host. The behavioural adaptations we describe may play an important role in the stability of cohabitations between host and inquiline termite species: by preventing conflict escalation, inquilines may improve considerably their chances of establishing a stable cohabitation with their hosts.

RevDate: 2020-09-04

Kloock A, Bonsall MB, KC King (2020)

Evolution and maintenance of microbe-mediated protection under occasional pathogen infection.

Ecology and evolution, 10(16):8634-8642 pii:ECE36555.

Every host is colonized by a variety of microbes, some of which can protect their hosts from pathogen infection. However, pathogen presence naturally varies over time in nature, such as in the case of seasonal epidemics. We experimentally coevolved populations of Caenorhabditis elegans worm hosts with bacteria possessing protective traits (Enterococcus faecalis), in treatments varying the infection frequency with pathogenic Staphylococcus aureus every host generation, alternating host generations, every fifth host generation, or never. We additionally investigated the effect of initial pathogen presence at the formation of the defensive symbiosis. Our results show that enhanced microbe-mediated protection evolved during host-protective microbe coevolution when faced with rare infections by a pathogen. Initial pathogen presence had no effect on the evolutionary outcome of microbe-mediated protection. We also found that protection was only effective at preventing mortality during the time of pathogen infection. Overall, our results suggest that resident microbes can be a form of transgenerational immunity against rare pathogen infection.

RevDate: 2020-09-04
CmpDate: 2020-09-04

Ajene IJ, Khamis FM, van Asch B, et al (2020)

Microbiome diversity in Diaphorina citri populations from Kenya and Tanzania shows links to China.

PloS one, 15(6):e0235348.

The Asian citrus psyllid (Diaphorina citri) is a key pest of Citrus spp. worldwide, as it acts as a vector for "Candidatus Liberibacter asiaticus (Las)", the bacterial pathogen associated with the destructive Huanglongbing (HLB) disease. Recent detection of D. citri in Africa and reports of Las-associated HLB in Ethiopia suggest that the citrus industry on the continent is under imminent threat. Endosymbionts and gut bacteria play key roles in the biology of arthropods, especially with regards to vector-pathogen interactions and resistance to antibiotics. Thus, we aim to profile the bacterial genera and to identify antibiotic resistance genes within the microbiome of different populations worldwide of D. citri. The metagenome of D. citri was sequenced using the Oxford Nanopore full-length 16S metagenomics protocol, and the "What's in my pot" (WIMP) analysis pipeline. Microbial diversity within and between D. citri populations was assessed, and antibiotic resistance genes were identified using the WIMP-ARMA workflow. The most abundant genera were key endosymbionts of D. citri ("Candidatus Carsonella", "Candidatus Profftella", and Wolbachia). The Shannon diversity index showed that D. citri from Tanzania had the highest diversity of bacterial genera (1.92), and D. citri from China had the lowest (1.34). The Bray-Curtis dissimilarity showed that China and Kenya represented the most diverged populations, while the populations from Kenya and Tanzania were the least diverged. The WIMP-ARMA analyses generated 48 CARD genes from 13 bacterial species in each of the populations. Spectinomycin resistance genes were the most frequently found, with an average of 65.98% in all the populations. These findings add to the knowledge on the diversity of the African D. citri populations and the probable introduction source of the psyllid in these African countries.

RevDate: 2020-09-04
CmpDate: 2020-09-04

Oosthuizen JR, Naidoo RK, Rossouw D, et al (2020)

Evolution of mutualistic behaviour between Chlorella sorokiniana and Saccharomyces cerevisiae within a synthetic environment.

Journal of industrial microbiology & biotechnology, 47(4-5):357-372.

Yeast and microalgae are microorganisms with widely diverging physiological and biotechnological properties. Accordingly, their fields of applications diverge: yeasts are primarily applied in processes related to fermentation, while microalgae are used for the production of high-value metabolites and green technologies such as carbon capture. Heterotrophic-autotrophic systems and synthetic ecology approaches have been proposed as tools to achieve stable combinations of such evolutionarily unrelated species. We describe an entirely novel synthetic ecology-based approach to evolve co-operative behaviour between winery wastewater isolates of the yeast Saccharomyces cerevisiae and microalga Chlorella sorokiniana. The data show that biomass production and mutualistic growth improved when co-evolved yeast and microalgae strains were paired together. Combinations of co-evolved strains displayed a range of phenotypes, including differences in amino acid profiles. Taken together, the results demonstrate that biotic selection pressures can lead to improved mutualistic growth phenotypes over relatively short time periods.

RevDate: 2020-09-04
CmpDate: 2020-09-04

Zhang Y, Wang J, GZ Han (2020)

Chalcid wasp paleoviruses bridge the evolutionary gap between bracoviruses and nudiviruses.

Virology, 542:34-39.

Polydnaviruses are obligate mutualists of parasitoid wasps and are divided into two genera, Bracovirus and Ichnovirus. Bracoviruses are thought to originate from a single integration of an ancestral nudivirus into the ancestor of microgastroid complex ~100 million years ago. However, all the known nudiviruses are only distantly related to bracoviruses, and much remains obscure about the origin of bracoviruses. Here we employ a paleovirological method to screen endogenous nudivirus-like elements across arthropods. Interestingly, we identify many endogenous nudivirus-like elements within the genome of Eurytoma brunniventris, a species of the Chalcidoidea superfamily. Among them, we find 14 core gene sequences are likely to be derived from a betanudivirus (designated EbrENV-β), suggesting that betanudivirus has been circulating in parasitoid wasps. Phylogenomic analysis suggests that EbrENV-β is the known closest relative of bracoviruses. Synteny analyses show the order of core genes is not well conserved between EbrENV-β and nudiviruses, revealing the dynamic nature of the evolution of nudivirus genome structures. Our findings narrow down the evolutionary gap between bracoviruses and nudiviruses and provide novel insights into the origin and evolution of polydnaviruses.

RevDate: 2020-09-04
CmpDate: 2020-09-04

Karimi E, Geslain E, KleinJan H, et al (2020)

Genome Sequences of 72 Bacterial Strains Isolated from Ectocarpus subulatus: A Resource for Algal Microbiology.

Genome biology and evolution, 12(1):3647-3655.

Brown algae are important primary producers and ecosystem engineers in the ocean, and Ectocarpus has been established as a laboratory model for this lineage. Like most multicellular organisms, Ectocarpus is associated with a community of microorganisms, a partnership frequently referred to as holobiont due to the tight interconnections between the components. Although genomic resources for the algal host are well established, its associated microbiome is poorly characterized from a genomic point of view, limiting the possibilities of using these types of data to study host-microbe interactions. To address this gap in knowledge, we present the annotated draft genome sequences of seventy-two cultivable Ectocarpus-associated bacteria. A screening of gene clusters related to the production of secondary metabolites revealed terpene, bacteriocin, NRPS, PKS-t3, siderophore, PKS-t1, and homoserine lactone clusters to be abundant among the sequenced genomes. These compounds may be used by the bacteria to communicate with the host and other microbes. Moreover, detoxification and provision of vitamin B pathways have been observed in most sequenced genomes, highlighting potential contributions of the bacterial metabolism toward host fitness and survival. The genomes sequenced in this study form a valuable resource for comparative genomic analyses and evolutionary surveys of alga-associated bacteria. They help establish Ectocarpus as a model for brown algal holobionts and will enable the research community to produce testable hypotheses about the molecular interactions within this complex system.

RevDate: 2020-09-03
CmpDate: 2020-09-03

Rosandić M, Vlahović I, V Paar (2019)

Novel look at DNA and life-Symmetry as evolutionary forcing.

Journal of theoretical biology, 483:109985.

After explanation of the Chargaff´s first parity rule in terms of the Watson-Crick base-pairing between the two DNA strands, the Chargaff´s second parity rule for each strand of DNA (also named strand symmetry), which cannot be explained by Watson-Crick base-pairing only, is still a challenging issue already fifty years. We show that during evolution DNA preserves its identity in the form of quadruplet A+T and C+G rich matrices based on purine-pyrimidine mirror symmetries of trinucleotides. Identical symmetries are present in our classification of trinucleotides and the genetic code table. All eukaryotes and almost all prokaryotes (bacteria and archaea) have quadruplet mirror symmetries in structural form and frequencies following the principle of Chargaff's second parity rule and Natural symmetry law of DNA creation and conservation. Some rare symbionts have mirror symmetry only in their structural form within each DNA strand. Based on our matrix analysis of closely related species, humans and Neanderthals, we find that the circular cycle of inverse proportionality between trinucleotides preserves identical relative frequencies of trinucleotides in each quadruplet and in the whole genome. According to our calculations, a change in frequencies in quadruplet matrices could lead to the creation of new species. Violation of quadruplet symmetries is practically inconsistent with life. DNA symmetries provide a key for understanding the restriction of disorder (entropy) due to mutations in the evolution of DNA.

RevDate: 2020-09-04
CmpDate: 2020-09-04

Kajtoch Ł, Kolasa M, Kubisz D, et al (2019)

Using host species traits to understand the Wolbachia infection distribution across terrestrial beetles.

Scientific reports, 9(1):847.

Knowledge of Wolbachia prevalence with respect to its hosts is restricted mainly to taxonomic/phylogenetic context. In contrast, relations between infection and most host's ecological and biological traits are poorly understood. This study aimed to elaborate on relations between bacteria and its beetle hosts in taxonomic and the ecological contexts. In particular, the goal is to verify which ecological and biological traits of beetles could cause them to be prone to be infected. Verification of Wolbachia infection status across 297 beetle taxa showed that approximately 27% of taxa are infected by supergroups A and B. Only minor support for coevolution between bacteria and its beetle hosts was observed in some genera of beetles, but in general coevolution between beetles and Wolbachia was rejected. Some traits of beetles were found to be unrelated to Wolbachia prevalence (type of range and thermal preferences); some traits were related with ambiguous effects (habitats, distribution, mobility and body size); some were substantially related (reproduction mode and trophy). The aforementioned summary does not show obvious patterns of Wolbachia prevalence and diversity in relation to host taxonomy, biology, and ecology. As both Wolbachia and Coleoptera are diverse groups, this lack of clear patterns is probably a reflection of nature, which is characterised by highly diversified and probably unstable relations.

RevDate: 2020-09-02

Berger A, Boscari A, Puppo A, et al (2020)

Both nitrate reductases and hemoglobins control the nitrogen-fixing symbiosis via the regulation of nitric oxide level.

Journal of experimental botany pii:5900761 [Epub ahead of print].

The interactions between legumes and Rhizobia lead to the establishment of a symbiotic relationship characterized by the formation of a new organ, the nodule, which facilitates the fixation of atmospheric nitrogen (N2) by nitrogenase through the creation of a hypoxic environment. Nitric oxide (NO) accumulates at each stage of the symbiotic process. It is involved in defense response, nodule organogenesis and development, nitrogen fixation metabolism and senescence induction. During symbiosis, either successively or simultaneously, NO regulates gene expression, modulates enzyme activities, and acts as a metabolic intermediate in energy regeneration processes via the phytoglobin-NO respiration and the bacterial denitrification pathway. Due to the transition from normoxia to hypoxia during the formation of the nodule and to the progressive presence of the bacterial partner in the growing nodules, NO production and degradation pathways change during the symbiotic process. This review analyses the different source and degradation pathways of NO, and highlights the role of nitrate reductases and hemoproteins of both the plant and the bacterial partners in the control of NO accumulation.

RevDate: 2020-09-02

Shinzato C, Khalturin K, Inoue J, et al (2020)

Eighteen coral genomes reveal the evolutionary origin of Acropora strategies to accommodate environmental changes.

Molecular biology and evolution pii:5900672 [Epub ahead of print].

The genus Acropora comprises the most diverse and abundant scleractinian corals (Anthozoa, Cnidaria) in coral reefs, the most diverse marine ecosystems on Earth. However, the genetic basis for the success and wide distribution of Acropora are unknown. Here we sequenced complete genomes of fifteen Acropora species and three other acroporid taxa belonging to the genera Montipora and Astreopora, to examine genomic novelties that explain their evolutionary success. We successfully obtained reasonable draft genomes of all eighteen species. Molecular dating indicates that the Acropora ancestor survived warm periods without sea ice from the mid or late Cretaceous to the Early Eocene, and that diversification of Acropora may have been enhanced by subsequent cooling periods. In general, the scleractinian gene repertoire is highly conserved; however, coral- or cnidarian-specific possible stress response genes are tandemly duplicated in Acropora. Enzymes that cleave dimethlysulfonioproprionate into dimethyl sulfide, which promotes cloud formation and combats greenhouse gasses, are the most duplicated genes in the Acropora ancestor. These may have been acquired by horizontal gene transfer from algal symbionts belonging to the family Symbiodiniaceae, or from coccolithophores, suggesting that although functions of this enzyme in Acropora are unclear, Acropora may have survived warmer marine environments in the past by enhancing cloud formation. In addition, possible anti-microbial peptides and symbiosis-related genes are under positive selection in Acropora, perhaps enabling adaptation to diverse environments. Our results suggest unique Acropora adaptations to ancient, warm marine environments, and provide insights into its capacity to adjust to rising seawater temperatures.

RevDate: 2020-09-02

Ma X, Li X, U Ludewig (2020)

Arbuscular mycorrhizal colonisation outcompetes root hairs in maize under low phosphorus availability.

Annals of botany pii:5900723 [Epub ahead of print].

BACKGROUND AND AIMS: An increase in the root hair length and density, as well as the development of arbuscular mycorrhiza symbiosis, are two alternative strategies of most plants to increase the root-soil surface area under phosphorus (P) deficiency. Across many plant species, root hair length and mycorrhization density are inversely correlated. Root architectures, rooting density and physiology also differ between species. This study aims to understand the relationship among root hairs, arbuscular mycorrhizal fungi (AMF) colonisation, plant growth, P acquisition, and mycorrhizal-specific Pi transporter gene expression of maize.

METHODS: Using nearly isogenic maize lines, the B73 wild type and the rth3 root hairless mutant, we quantified the effect of root hairs and AMF infection in a calcareous soil under P-deficiency through a combined analysis of morphological, physiological and molecular factors.

KEY RESULTS: Wild type root hairs extended the rhizosphere for acid phosphatase activity by 0.5 mm compared to the rth3 hairless mutant, as measured by in situ zymography. Total root length of the wild type was longer than rth3 under P-deficiency. Higher AMF colonisation and mycorrhiza-induced phosphate transporter gene expression were identified in the mutant under P-deficiency, but plant growth and P acquisition were similar between mutant and the wild type. Ultimately, the mycorrhizal dependency of maize was 33% higher than the root hair dependency.

CONCLUSIONS: The results identified a larger mycorrhizal dependency than root hair dependency under P-deficiency in maize. Root hairs and AMF inoculation are two alternative ways to increase Pi acquisition under P-deficiency, but these two strategies compete with each other.

RevDate: 2020-09-02

Saha I, Datta S, D Biswas (2020)

Exploring the Role of Bacterial Extracellular Polymeric Substances for Sustainable Development in Agriculture.

Current microbiology pii:10.1007/s00284-020-02169-y [Epub ahead of print].

The incessant need to increase crop yields has led to the development of many chemical fertilizers containing NPK (nitrogen-phosphorous-potassium) which can degrade soil health in the long term. In addition, these fertilizers are often leached into nearby water bodies causing algal bloom and eutrophication. Bacterial secondary metabolites exuded into the extracellular space, termed extracellular polymeric substances (EPS) have gained commercial significance because of their biodegradability, non-toxicity, and renewability. In many habitats, bacterial communities faced with adversity will adhere together by production of EPS which also serves to bond them to surfaces. Typically, hygroscopic, EPS retain moisture in desiccating conditions and modulate nutrient exchange. Many plant growth-promoting bacteria (PGPR) combat harsh environmental conditions like salinity, drought, and attack of pathogens by producing EPS. The adhesive nature of EPS promotes soil aggregation and restores moisture thus combating soil erosion and promoting soil fertility. In addition, these molecules play vital roles in maintaining symbiosis and nitrogen fixation thus enhancing sustainability. Thus, along with other commercial applications, EPS show promising avenues for improving agricultural productivity thus helping to address land scarcity as well as minimizing environmental pollution.

RevDate: 2020-09-02

Shi T, Niu G, Kvitt H, et al (2020)

Untangling ITS2 Genotypes of Algal Symbionts in Zooxanthellate Corals.

Molecular ecology resources [Epub ahead of print].

Collectively called zooxanthellae, photosynthetic dinoflagellates in the family Symbiodiniaceae are typical endosymbionts that unequivocally mediate coral responses to environmental changes. Symbiodiniaceae are genetically diverse, encompassing at least nine phylogenetically distinct genera (clades A-I). The ribosomal internal transcribed spacer 2 (ITS2) region is commonly utilized for determining Symbiodiniaceae diversity within clades. However, ITS2 is often inadvertently interpreted together with the tailing part of the ribosomal RNA genes (5.8S and 28S or equivalent), leading to unresolved taxonomy and equivocal annotations. To overcome this hurdle, we mined in GenBank and expert reference databases for ITS2 sequences of Symbiodiniaceae having explicit boundaries with adjacent rRNAs. We profiled a Hidden Markov Model of the ITS2-proximal 5.8S-28S rRNA interaction, which was shown to facilitate the delimitation of Symbiodiniaceae ITS2 from GenBank, whilst considerably reducing sequence ambiguity and redundancy in reference databases. The delineation of ITS2 sequences unveiled intra-clade sequence diversity and inter-clade secondary structure conservation. We compiled the clean data into a non-redundant database that archives the largest number of Symbiodiniaceae ITS2 sequences known to date with definite genotype/subclade representations and well-defined secondary structures. This database provides a fundamental reference catalog for consistent and precise genotyping of Symbiodiniaceae and a tool for automated annotation of user-supplied sequences.

RevDate: 2020-09-02

Bennett BD, Essock-Burns T, EG Ruby (2020)

HbtR, a Heterofunctional Homolog of the Virulence Regulator TcpP, Facilitates the Transition between Symbiotic and Planktonic Lifestyles in Vibrio fischeri.

mBio, 11(5): pii:mBio.01624-20.

The bioluminescent bacterium Vibrio fischeri forms a mutually beneficial symbiosis with the Hawaiian bobtail squid, Euprymna scolopes, in which the bacteria, housed inside a specialized light organ, produce light used by the squid in its nocturnal activities. Upon hatching, E. scolopes juveniles acquire V. fischeri from the seawater through a complex process that requires, among other factors, chemotaxis by the bacteria along a gradient of N-acetylated sugars into the crypts of the light organ, the niche in which the bacteria reside. Once inside the light organ, V. fischeri transitions into a symbiotic, sessile state in which the quorum-signaling regulator LitR induces luminescence. In this work we show that expression of litR and luminescence are repressed by a homolog of the Vibrio cholerae virulence factor TcpP, which we have named HbtR. Further, we demonstrate that LitR represses genes involved in motility and chemotaxis into the light organ and activates genes required for exopolysaccharide production.IMPORTANCE TcpP homologs are widespread throughout the Vibrio genus; however, the only protein in this family described thus far is a V. cholerae virulence regulator. Here, we show that HbtR, the TcpP homolog in V. fischeri, has both a biological role and regulatory pathway completely unlike those in V. cholerae Through its repression of the quorum-signaling regulator LitR, HbtR affects the expression of genes important for colonization of the E. scolopes light organ. While LitR becomes activated within the crypts and upregulates luminescence and exopolysaccharide genes and downregulates chemotaxis and motility genes, it appears that HbtR, upon expulsion of V. fischeri cells into seawater, reverses this process to aid the switch from a symbiotic to a planktonic state. The possible importance of HbtR to the survival of V. fischeri outside its animal host may have broader implications for the ways in which bacteria transition between often vastly different environmental niches.

RevDate: 2020-09-02

Wang Y, Wei X, Bian Z, et al (2020)

Coregulation of dimorphism and symbiosis by cyclic AMP signaling in the lichenized fungus Umbilicaria muhlenbergii.

Proceedings of the National Academy of Sciences of the United States of America pii:2005109117 [Epub ahead of print].

Umbilicaria muhlenbergii is the only known dimorphic lichenized fungus that grows in the hyphal form in lichen thalli but as yeast cells in axenic cultures. However, the regulation of yeast-to-hypha transition and its relationship to the establishment of symbiosis are not clear. In this study, we show that nutrient limitation and hyperosmotic stress trigger the dimorphic change in U. muhlenbergii Contact with algal cells of its photobiont Trebouxia jamesii induced pseudohyphal growth. Treatments with the cAMP diphosphoesterase inhibitor IBMX (3-isobutyl-1-methylxanthine) induced pseudohyphal/hyphal growth and resulted in the differentiation of heavily melanized, lichen cortex-like structures in culture, indicating the role of cAMP signaling in regulating dimorphism. To confirm this observation, we identified and characterized two Gα subunits UmGPA2 and UmGPA3 Whereas deletion of UmGPA2 had only a minor effect on pseudohyphal growth, the ΔUmgpa3 mutant was defective in yeast-to-pseudohypha transition induced by hyperosmotic stress or T. jamesii cells. IBMX treatment suppressed the defect of ΔUmgpa3 in pseudohyphal growth. Transformants expressing the UmGPA3G45V or UmGPA3Q208L dominant active allele were enhanced in the yeast-to-pseudohypha transition and developed pseudohyphae under conditions noninducible to the wild type. Interestingly, T. jamesii cells in close contact with pseudohyphae of UmGPA3G45V and UmGPA3Q208L transformants often collapsed and died after coincubation for over 72 h, indicating that improperly regulated pseudohyphal growth due to dominant active mutations may disrupt the initial establishment of symbiotic interaction between the photobiont and mycobiont. Taken together, these results show that the cAMP-PKA pathway plays a critical role in regulating dimorphism and symbiosis in U. muhlenbergii.

RevDate: 2020-09-02

Müller LM, Campos-Soriano L, Lévesque-Tremblay V, et al (2020)

Constitutive overexpression of RAM1 leads to an increase in arbuscule density in Brachypodium distachyon.

Plant physiology pii:pp.20.00997 [Epub ahead of print].

Arbuscular mycorrhizal (AM) symbiosis is a mutually beneficial association of plants and fungi of the sub-phylum Glomeromycotina. Endosymbiotic AM fungi colonize the inner cortical cells of the roots, where they form branched hyphae called arbuscules that function in nutrient exchange with the plant. To support arbuscule development and subsequent bidirectional nutrient exchange, the root cortical cells undergo substantial transcriptional re-programming. REDUCED ARBUSCULAR MYCORRHIZA 1 (RAM1), previously studied in several dicot plant species, is a major regulator of this cortical cell transcriptional program. Here, we generated ram1 mutants and RAM1 overexpressors in a monocot, Brachypodium distachyon. The AM phenotypes of two ram1 lines revealed that RAM1 is only partly required to enable arbuscule development in B. distachyon. Transgenic lines constitutively overexpressing BdRAM1 showed constitutive expression of AM-inducible genes even in the shoots. Following inoculation with AM fungi, BdRAM1-overexpressing roots showed higher arbuscule densities relative to controls, indicating the potential to manipulate the relative proportion of symbiotic interfaces via modulation of RAM1. However, the overexpressors also show altered expression of hormone biosynthesis genes and aberrant growth patterns including stunted bushy shoots and poor seed set. While these phenotypes possibly provide additional clues about the scope of influence of BdRAM1, they also indicate that directed approaches to increase the density of symbiotic interfaces will require a more focused, potentially cell-type specific manipulation of transcription factor gene expression.

RevDate: 2020-09-02

Leftwich PT, Edgington MP, T Chapman (2020)

Transmission efficiency drives host-microbe associations.

Proceedings. Biological sciences, 287(1934):20200820.

Sequencing technologies have fuelled a rapid rise in descriptions of microbial communities associated with hosts, but what is often harder to ascertain is the evolutionary significance of these symbioses. Here, we review the role of vertical (VT), horizontal (HT), environmental acquisition and mixed modes of transmission (MMT), in the establishment of animal host-microbe associations. We then model four properties of gut microbiota proposed as key to promoting animal host-microbe relationships: modes of transmission, host reproductive mode, host mate choice and host fitness. We found that: (i) MMT led to the highest frequencies of host-microbe associations, and that some environmental acquisition or HT of microbes was required for persistent associations to form unless VT was perfect; (ii) host reproductive mode (sexual versus asexual) and host mate choice (for microbe carriers versus non-carriers) had little impact on the establishment of host-microbe associations; (iii) host mate choice did not itself lead to reproductive isolation, but could reinforce it; and (iv) changes in host fitness due to host-microbe associations had a minimal impact upon the formation of co-associations. When we introduced a second population, into which host-microbe carriers could disperse but in which environmental acquisition did not occur, highly efficient VT was required for host-microbe co-associations to persist. Our study reveals that transmission mode is of key importance in establishing host-microbe associations.

RevDate: 2020-09-02

Pandharikar G, Gatti JL, Simon JC, et al (2020)

Aphid infestation differently affects the defences of nitrate-fed and nitrogen-fixing Medicago truncatula and alters symbiotic nitrogen fixation.

Proceedings. Biological sciences, 287(1934):20201493.

Legumes can meet their nitrogen requirements through root nodule symbiosis, which could also trigger plant systemic resistance against pests. The pea aphid Acyrthosiphon pisum, a legume pest, can harbour different facultative symbionts (FS) influencing various traits of their hosts. It is therefore worth determining if and how the symbionts of the plant and the aphid modulate their interaction. We used different pea aphid lines without FS or with a single one (Hamiltonella defensa, Regiella insecticola, Serratia symbiotica) to infest Medicago truncatula plants inoculated with Sinorhizobium meliloti (symbiotic nitrogen fixation, SNF) or supplemented with nitrate (non-inoculated, NI). The growth of SNF and NI plants was reduced by aphid infestation, while aphid weight (but not survival) was lowered on SNF compared to NI plants. Aphids strongly affected the plant nitrogen fixation depending on their symbiotic status, suggesting indirect relationships between aphid- and plant-associated microbes. Finally, all aphid lines triggered expression of Pathogenesis-Related Protein 1 (PR1) and Proteinase Inhibitor (PI), respective markers for salicylic and jasmonic pathways, in SNF plants, compared to only PR1 in NI plants. We demonstrate that the plant symbiotic status influences plant-aphid interactions while that of the aphid can modulate the amplitude of the plant's defence response.

RevDate: 2020-09-02

Brückner A, Kaltenpoth M, M Heethoff (2020)

De novo biosynthesis of simple aromatic compounds by an arthropod (Archegozetes longisetosus).

Proceedings. Biological sciences, 287(1934):20201429.

The ability to synthesize simple aromatic compounds is well known from bacteria, fungi and plants, which all share an exclusive biosynthetic route-the shikimic acid pathway. Some of these organisms further evolved the polyketide pathway to form core benzenoids via a head-to-tail condensation of polyketide precursors. Arthropods supposedly lack the ability to synthesize aromatics and instead rely on aromatic amino acids acquired from food, or from symbiotic microorganisms. The few studies purportedly showing de novo biosynthesis via the polyketide synthase (PKS) pathway failed to exclude endosymbiotic bacteria, so their results are inconclusive. We investigated the biosynthesis of aromatic compounds in defence secretions of the oribatid mite Archegozetes longisetosus. Exposing the mites to a diet containing high concentrations of antibiotics removed potential microbial partners but did not affect the production of defensive benzenoids. To gain insights into benzenoid biosynthesis, we fed mites with stable-isotope labelled precursors and monitored incorporation with mass spectrometry. Glucose, malonic acid and acetate, but not phenylalanine, were incorporated into the benzenoids, further evidencing autogenous biosynthesis. Whole-transcriptome sequencing with hidden Markov model profile search of protein domain families and subsequent phylogenetic analysis revealed a putative PKS domain similar to an actinobacterial PKS, possibly indicating a horizontal gene transfer.

RevDate: 2020-09-02
CmpDate: 2020-09-02

Khanna K, Sharma A, Ohri P, et al (2019)

Impact of Plant Growth Promoting Rhizobacteria in the Orchestration of Lycopersicon esculentum Mill. Resistance to Plant Parasitic Nematodes: A Metabolomic Approach to Evaluate Defense Responses Under Field Conditions.

Biomolecules, 9(11):.

The present study deals with biological control of Meloidogyne incognita in 45-days old Lycopersicon esculentum, inoculated with Pseudomonas aeruginosa(M1) and Burkholderia gladioli (M2). The improved plant growth and biomass of nematode infested Plant growth promoting rhizobacteria (PGPR) inoculated plants was observed. Remarkable reduction in the numbers of second stage juvenile (J2s), root galls was recorded after treatment of microbes relative to experimental controls. Moreover, the lowered activities of oxidative stress markers (H2O2 (hydrogen peroxide), O2- (superoxide anion), malondialdehyde (MDA)) was estimated in plants after rhizobacterial supplementation. Higher activities of enzymatic (SOD (Superoxide dismutase), POD (Guaiacol peroxidase), CAT (Catalase), GPOX (Glutathione peroxidase), APOX (Ascorbate peroxidase), GST (Glutathione-S-transferase), GR (Glutathione reductase), DHAR (Dehydroascorbate reductase), PPO (Polyphenol oxidase)) and non-enzymatic (glutathione, ascorbic acid, tocopherol) antioxidants were further determined in nematode infected plants following the addition of bacterial strains. The upregulation of photosynthetic activities were depicted by evaluating plant pigments and gas exchange attributes. An increase in the levels of phenolic compounds (total phenols, flavonoids, anthocyanins), osmoprotectants (total osmolytes, carbohydrates, reducing sugars, trehalose, proline, glycine betaine, free amino acids) and organic acids (fumaric, succinic, citric, malic acid) were reflected in infected plants, showing further enhancement after application of biocontrol agents. The study revealed the understanding of plant metabolism, along with the initiative to commercially exploit the biocontrol agents as an alternative to chemical nematicides in infected fields for sustainable agriculture.

RevDate: 2020-09-02
CmpDate: 2020-09-02

Schiessl K, Lilley JLS, Lee T, et al (2019)

NODULE INCEPTION Recruits the Lateral Root Developmental Program for Symbiotic Nodule Organogenesis in Medicago truncatula.

Current biology : CB, 29(21):3657-3668.e5.

To overcome nitrogen deficiencies in the soil, legumes enter symbioses with rhizobial bacteria that convert atmospheric nitrogen into ammonium. Rhizobia are accommodated as endosymbionts within lateral root organs called nodules that initiate from the inner layers of Medicago truncatula roots in response to rhizobial perception. In contrast, lateral roots emerge from predefined founder cells as an adaptive response to environmental stimuli, including water and nutrient availability. CYTOKININ RESPONSE 1 (CRE1)-mediated signaling in the pericycle and in the cortex is necessary and sufficient for nodulation, whereas cytokinin is antagonistic to lateral root development, with cre1 showing increased lateral root emergence and decreased nodulation. To better understand the relatedness between nodule and lateral root development, we undertook a comparative analysis of these two root developmental programs. Here, we demonstrate that despite differential induction, lateral roots and nodules share overlapping developmental programs, with mutants in LOB-DOMAIN PROTEIN 16 (LBD16) showing equivalent defects in nodule and lateral root initiation. The cytokinin-inducible transcription factor NODULE INCEPTION (NIN) allows induction of this program during nodulation through activation of LBD16 that promotes auxin biosynthesis via transcriptional induction of STYLISH (STY) and YUCCAs (YUC). We conclude that cytokinin facilitates local auxin accumulation through NIN promotion of LBD16, which activates a nodule developmental program overlapping with that induced during lateral root initiation.

RevDate: 2020-09-01

Balestrini R, Brunetti C, Chitarra W, et al (2020)

Photosynthetic Traits and Nitrogen Uptake in Crops: Which Is the Role of Arbuscular Mycorrhizal Fungi?.

Plants (Basel, Switzerland), 9(9): pii:plants9091105.

Arbuscular mycorrhizal (AM) fungi are root symbionts that provide mineral nutrients to the host plant in exchange for carbon compounds. AM fungi positively affect several aspects of plant life, improving nutrition and leading to a better growth, stress tolerance, and disease resistance and they interact with most crop plants such as cereals, horticultural species, and fruit trees. For this reason, they receive expanding attention for the potential use in sustainable and climate-smart agriculture context. Although several positive effects have been reported on photosynthetic traits in host plants, showing improved performances under abiotic stresses such as drought, salinity and extreme temperature, the involved mechanisms are still to be fully discovered. In this review, some controversy aspects related to AM symbiosis and photosynthesis performances will be discussed, with a specific focus on nitrogen acquisition-mediated by AM fungi.

RevDate: 2020-09-01

Ueno AC, Gundel PE, Ghersa CM, et al (2020)

Ontogenetic and trans-generational dynamics of a vertically transmitted fungal symbiont in an annual host plant in ozone-polluted settings.

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

Tropospheric ozone is an abiotic stress of increasing importance in the context of global climate change. This greenhouse gas is a potent phytotoxic molecule with demonstrated negative effects on crop yield and natural ecosystems. Recently, oxidative stress has been proposed as a mechanism that could regulate the interaction between cool-season grasses and Epichloë endophytes. We hypothesized that exposure of Lolium multiflorum plants, hosting endophytes to an ozone-polluted environment at different ontogenetic phases, would impact the trans-generational dynamics of the vertically transmitted fungal symbiont. Here, we found that the ozone-induced stress on the mother plants did not affect the endophyte vertical transmission but it impaired the persistence of the fungus in the seed exposed to artificial ageing. Endophyte longevity in seed was reduced by exposure of the mother plant to ozone. Although ozone exposure did not influence either the endophyte mycelial concentration or their compound defences (loline alkaloids), a positive correlation was observed between host fitness and the concentration of endophyte-derived defence compounds. This suggests that fungal defences in grass seeds were not all produced in situ but remobilized from the vegetative tissues. Our study reveals ozone trans-generational effects on the persistence of a beneficial symbiont in a host grass.

RevDate: 2020-08-31

Hossfeld DJ, Ling L, CS Cohen (2020)

Experimental investigation of tidal and freshwater influence on Symbiodiniaceae abundance in Anthopleura elegantissima.

PloS one, 15(8):e0238361 pii:PONE-D-19-25403.

The San Francisco Bay outflow creates a tidally influenced low-salinity plume that affects adjacent coastal sites. In the study region, Anthopleura elegantissima (Cnidaria; Anthozoa) hosts a single symbiont, the dinoflagellate Breviolum muscatinei. Salinity, temperature, and aerial stress induce a bleaching response similar to corals where symbionts are expelled, causing further energetic stress. Using field observations of environmental conditions and symbiont abundance at sites on a gradient of exposure to estuarine outflow, along with a fully crossed multifactorial lab experiment, we tested for changes in symbiont abundance in response to various combinations of three stressors. Lab experiments were designed to mimic short term outflow events with low salinity, high temperature, and aerial exposure treatments. The lab aerial exposure treatment was a statistically significant factor in suppressing symbiont repopulation (ANOVA, p = .017). In the field, symbiont density decreased with increasing tidal height at the site closest to freshwater outflow (ANOVA, p = .007), suggesting that aerial exposure may affect symbiont density more than sea surface temperature and salinity. Unanticipated documentation of survival in 9 months of sand burial and subsequent repopulation of symbionts is reported as a six-month extension to past observations, exemplifying strong tolerance to environmental insult in this Cnidarian mutualism. The study of this symbiosis is useful in examining predicted changes in ocean conditions in tidepool communities and considering relative sources of stress.

RevDate: 2020-08-31

Luo Y, Liu D, Jiao S, et al (2020)

Identification of Robinia pseudoacacia target proteins responsive to Mesorhizobium amphore CCNWGS0123 effector protein NopT.

Journal of experimental botany pii:5899690 [Epub ahead of print].

Nodulation outer proteins secreted via type 3 secretion systems are involved in the process of symbiosis between legume plants and rhizobia. To study the function of NopT in symbiosis, we mutated nopT in Mesorhizobium amphore CCNWGS0123 (GS0123), which could nodulate black locust (Robinia pseudoacacia). The nopT mutant induced higher jasmonic acid, salicylic acid, and hydrogen peroxide accumulation levels in the roots of R. pseudoacacia compared to wild-type GS0123. The △nopT mutant induced higher disease-resistant gene expression 72 h post-inoculation (hpi), whereas GS0123 induced higher disease-resistant gene expression earlier, 36 hpi. Compared to the nopT mutant, GS0123 induced the up-regulation of most genes at 36 hpi and down-regulation of most genes at 72 hpi. Proteolytically active NopT_GS0123 induced hypersensitive responses when expressed transiently in the leaves of tobacco (Nicotiana benthamiana). Two NopT_GS0123 targets in R. pseudoacacia were identified, ATP-citrate synthase alpha chain protein 2 and hypersensitive-induced response protein. Their interactions with NopT_GS0123 triggered resistance by the plant immune system. In conclusion, NopT_GS0123 inhibited the host plant immune system and had minimal effect on nodulation in R. pseudoacacia. The results of the present study reveal the underlying molecular mechanism of NopT function in plant-symbiont interactions.

RevDate: 2020-08-31

Pandey U, Saini J, Kumar M, et al (2020)

Normative Baseline for Radiomics in Brain MRI: Evaluating the Robustness, Regional Variations, and Reproducibility on FLAIR Images.

Journal of magnetic resonance imaging : JMRI [Epub ahead of print].

BACKGROUND: Radiomics in neuroimaging has gained momentum as a noninvasive prediction tool not only to differentiate between types of brain tumors, but also to create phenotypic signatures in neurological and neuropsychiatric disorders. However, there is currently little understating about the robustness and reproducibility of radiomic features in a baseline normative population.

PURPOSE: To investigate the intra- and interscanner reproducibility, spatial robustness, and sensitivity of radiomics on fluid attenuation inversion recovery (FLAIR) images, which are widely used in neuro-oncology investigations.

STUDY TYPE: Retrospective.

POPULATION: Three separate datasets of healthy controls: 1) 87 subjects (age range 12-64 years), 2) intrascanner three timepoints, four subjects, and 3) interscanner, eight subjects at three different sites.

FIELD STRENGTH/SEQUENCE: T2 -weighted FLAIR at 1.5T and 3.0T.

ASSESSMENT: Spatial variance across lobes, and their relation with age/gender, intra- and inter-scanner reproducibility (with and without site harmonization) of radiomics.

STATISTICAL TESTS: Analysis of variance (ANOVA), interclass correlation (ICC), coefficient of variation (CoV), Bland-Altman analysis.

RESULTS: Analysis of data revealed no differences between genders; however, multiple radiomic features were highly associated with age (P < 0.05). Spatial variability was also evaluated where only 29.04% gray matter and 38.7% white matter features demonstrated an ICC >0.5. Furthermore, the results demonstrated intra-scanner reliability (ICC >0.5); however, inter-scanner reproducibility was poor, with ICC < 0.5 for 82% gray matter and 78.5% white matter features. The inter-scanner reliability improved (ICC < 0.5 for 39.67% gray matter and 38% white matter features) using site-harmonization techniques.

DATA CONCLUSION: These findings suggest that, accounting for age, spatial locations in radiomics-based analysis and use of intersite radiomics harmonization is crucial before interpreting these features for pathological inference.

LEVEL OF EVIDENCE: 3.

TECHNICAL EFFICACY STAGE: 1.

RevDate: 2020-08-30

Keller J, Delcros P, Libourel C, et al (2020)

DELLA family duplication events lead to different selective constraints in angiosperms.

Genetica pii:10.1007/s10709-020-00102-6 [Epub ahead of print].

Gibberellic acid (GA) is a major plant hormone involved in several biological processes from the flowering to the symbiosis with microorganisms. Thus, the GA regulation is crucial for plant biology. This regulation occurs via the DELLA proteins that belong to the GRAS transcription factor family. DELLA proteins are characterised by a DELLA N-terminal and a GRAS C-terminal domains. It is well known that DELLA activity appears after the bryophytes divergence and then evolved in the vascular plant lineages. Here we present the phylogeny of DELLA across 75 species belonging to various lineages from algae, liverworts and angiosperms. Our study confirmed two main duplication events, the first occurring before the angiosperms divergence and the other specific to the eudicots lineage. Comparative analysis of DELLA subclades in angiosperms revealed the loss in Poaceae and strong alteration in other species of the DELLA functional domain in the DELLA2 clade. In addition, molecular evolution analysis suggests that each of the clades (named DELLA1.1, DELLA1.2 and DELLA2) evolved differently but copies of each subclade are under strong purifying selection. This also suggests that, although the DELLA functional domain is altered in DELLA2, DELLA2 orthologs are still functional and operate in a different way compared to DELLA1 copies. In angiosperms, additional duplication events occurred and led to duplicate copies in species, genus or family such as in the Fabaceae subfamily Papilionoideae. This duplication led to the formation of additional paralogs in the DELLA1.2 subclade (DELLA1.2.1 and DELLA1.2.2). Interestingly, both copies appeared to be under relaxing selection revealing different evolutionary fate of the DELLA duplicated copies.

RevDate: 2020-08-31
CmpDate: 2020-08-31

Yeakel JD, Pires MM, de Aguiar MAM, et al (2020)

Diverse interactions and ecosystem engineering can stabilize community assembly.

Nature communications, 11(1):3307.

The complexity of an ecological community can be distilled into a network, where diverse interactions connect species in a web of dependencies. Species interact directly with each other and indirectly through environmental effects, however to our knowledge the role of these ecosystem engineers has not been considered in ecological network models. Here we explore the dynamics of ecosystem assembly, where species colonization and extinction depends on the constraints imposed by trophic, service, and engineering dependencies. We show that our assembly model reproduces many key features of ecological systems, such as the role of generalists during assembly, realistic maximum trophic levels, and increased nestedness with mutualistic interactions. We find that ecosystem engineering has large and nonlinear effects on extinction rates. While small numbers of engineers reduce stability by increasing primary extinctions, larger numbers of engineers increase stability by reducing primary extinctions and extinction cascade magnitude. Our results suggest that ecological engineers may enhance community diversity while increasing persistence by facilitating colonization and limiting competitive exclusion.

RevDate: 2020-08-31
CmpDate: 2020-08-31

Schulze J, Liese R, Ballesteros G, et al (2020)

Ammonium acts systemically while nitrate exerts an additional local effect on Medicago truncatula nodules.

Plant science : an international journal of experimental plant biology, 292:110383.

Symbiotic nitrogen fixation (SNF) has a high energetic cost for legume plants; legumes thus reduce SNF when soil N is available. The present study aimed to increase our understanding regarding the impacts of the two principal forms of available N in soils (ammonium and nitrate) on SNF. We continuously measured the SNF of Medicago truncatula under controlled conditions. This permitted nodule sampling for comparative transcriptome profiling at points connected to the nodules' reaction following ammonium or nitrate applications. The N component of both ions systemically induced a rhythmic pattern of SNF, while the activity in control plants remained constant. This rhythmic activity reduced the per-day SNF. The nitrate ion had additional local effects; the more pronounced were a strong downregulation of leghaemoglobin, nodule cysteine-rich (NCR) peptides and nodule-enhanced nicotianamine synthase (neNAS). The neNAS has proven to be of importance for nodule functioning. Although other physiological impacts of nitrate on nodules were observed (e.g. nitrosylation of leghaemoglobin), the main effect was a rapid ion-specific and organ-specific change in gene expression levels. Contrastingly, during the first hours after ammonium applications, the transcriptome remained virtually unaffected. Therefore, nitrate-induced genes could be key for increasing the nitrate tolerance of SNF.

RevDate: 2020-08-31
CmpDate: 2020-08-31

Knobloch S, Jóhannsson R, VÞ Marteinsson (2020)

Genome analysis of sponge symbiont 'Candidatus Halichondribacter symbioticus' shows genomic adaptation to a host-dependent lifestyle.

Environmental microbiology, 22(1):483-498.

The marine sponge Halichondria panicea inhabits coastal areas around the globe and is a widely studied sponge species in terms of its biology, yet the ecological functions of its dominant bacterial symbiont 'Candidatus Halichondribacter symbioticus' remain unknown. Here, we present the draft genome of 'Ca. H. symbioticus' HS1 (2.8 Mbp, ca. 87.6% genome coverage) recovered from the sponge metagenome of H. panicea in order to study functions and symbiotic interactions at the genome level. Functional genome comparison of HS1 against closely related free-living seawater bacteria revealed a reduction of genes associated with carbohydrate transport and transcription regulation, pointing towards a limited carbohydrate metabolism, and static transcriptional dynamics reminiscent of other bacterial symbionts. In addition, HS1 was enriched in sponge symbiont specific gene families related to host-symbiont interactions and defence. Similarity in the functional gene repertoire between HS1 and a phylogenetically more distant symbiont in the marine sponge Aplysina aerophoba, based on COG category distribution, suggest a convergent evolution of symbiont specific traits and general metabolic features. This warrants further investigation into convergent genomic evolution of symbionts across different sponge species and habitats.

RevDate: 2020-08-29

Li L, Wang M, Li L, et al (2020)

Endosymbionts of vent-dwelling metazoans in PACManus-diversity and potential adaptive features revealed by genome analysis.

Applied and environmental microbiology pii:AEM.00815-20 [Epub ahead of print].

Deep-sea hydrothermal vent communities are dominated by invertebrates, namely bathymodiolin mussels, siboglinid tubeworms, and provannid snails. Symbiosis is considered key to successful colonization by these sedentary species in such extreme environments. In the PACManus vent fields, snails, tubeworms, and mussels each colonized a niche with distinct geochemical characteristics. To better understand the metabolic potentials and genomic features contributing to host-environment adaptation, we compared genomes of the symbionts of Bathymodiolus manusensis, Arcovestia ivanovi, and Alviniconcha boucheti sampled at PACManus and discuss their environmental adaptive features. We found that B. manusensis and A. ivanovi are colonized by γ-proteobacteria from distinct clades, whereas endosymbionts of B. manusensis feature high intraspecific heterogeneity with differing metabolic potentials. A. boucheti harbored three novel ϵ-proteobacteria symbionts, suggesting potential species-level diversity of snail symbionts . Genome comparisons revealed gene families related to low pH homeostasis, metal resistance, oxidative stress resistance, environmental sensing/responses, and chemotaxis and motility were most abundant in A. ivanovi's symbiont, followed by symbionts of the vent-mouth-dwelling snail A. boucheti, and relatively low in the vent-periphery-dwelling mussel B. manusensis, which is consistent with their environmental adaptation and host-symbiont interactions. Gene families classified to host interaction/attachment, virulence factors/toxins, and eukaryotic-like proteins were most abundant in symbionts of mussels and least abundant in those of snails, indicating these symbionts may differ in their host-colonization strategy. Comparison of ϵ-symbionts to non-symbionts demonstrated the expanded gene families in symbionts were related to VB12 synthesis, toxin-antitoxin, methylation, and lipopolysaccharide biosynthesis, suggesting these are vital to symbiotic establishment and development in ϵ-proteobacteriaImportance Deep-sea hydrothermal vents are dominated by several invertebrate species. The establishment of symbiosis has long been thought to be the key to successful colonization by these sedentary species in such harsh environments. Yet the relationships between symbiotic bacteria and their hosts, and their role in environment adaptations generally remain unclear. In this paper, we show that the distribution of three host species showed characteristic niche partitioning in the Manus Basin, giving us opportunity to understand how they adapt to their particular habitats. This study also revealed three novel genomes of symbionts from the snails of A. boucheti Combined with a dataset of other ectosymbiont and free-living bacteria, genome comparisons of the snail endosymbionts pointed to several genetic traits that may have contributed to the lifestyle shift into the epithelial cells in ϵ-proteobacteria These findings could increase our understanding of invertebrate-endosymbiont in deep-sea ecosystems.

RevDate: 2020-08-29

Valadares RBS, Perotto S, Lucheta AR, et al (2020)

Proteomic and Transcriptomic Analyses Indicate Metabolic Changes and Reduced Defense Responses in Mycorrhizal Roots of Oeceoclades maculata (Orchidaceae) Collected in Nature.

Journal of fungi (Basel, Switzerland), 6(3): pii:jof6030148.

Orchids form endomycorrhizal associations with fungi mainly belonging to basidiomycetes. The molecular events taking place in orchid mycorrhiza are poorly understood, although the cellular changes necessary to accommodate the fungus and to control nutrient exchanges imply a modulation of gene expression. Here, we used proteomics and transcriptomics to identify changes in the steady-state levels of proteins and transcripts in the roots of the green terrestrial orchid Oeceoclades maculata. When mycorrhizal and non-mycorrhizal roots from the same individuals were compared, 94 proteins showed differential accumulation using the label-free protein quantitation approach, 86 using isobaric tagging and 60 using 2D-differential electrophoresis. After de novo assembly of transcriptomic data, 11,179 plant transcripts were found to be differentially expressed, and 2175 were successfully annotated. The annotated plant transcripts allowed the identification of up- and down-regulated metabolic pathways. Overall, proteomics and transcriptomics revealed, in mycorrhizal roots, increased levels of transcription factors and nutrient transporters, as well as ethylene-related proteins. The expression pattern of proteins and transcripts involved in plant defense responses suggested that plant defense was reduced in O. maculata mycorrhizal roots sampled in nature. These results expand our current knowledge towards a better understanding of the orchid mycorrhizal symbiosis in adult plants under natural conditions.

RevDate: 2020-08-29

Koch EJ, M McFall-Ngai (2018)

Model systems for the study of how symbiotic associations between animals and extracellular bacterial partners are established and maintained.

Drug discovery today. Disease models, 28:3-12.

This contribution describes the current state of experimental model development and use as a strategy for gaining insight into the form and function of certain types of host-microbe associations. Development of quality models for the study of symbiotic systems will be critical not only to facilitate an understanding of mechanisms underlying symbiosis, but also for providing insights into how drug development can promote healthy animal-microbe interactions as well as the treatment of pathogenic infections. Because of the growing awareness over the last decade of the importance of symbiosis in biology, a number of model systems has emerged to examine how these partnerships are maintained within and across generations of the host. The focus here will be upon host-bacterial symbiotic systems that, as in humans, (i) are acquired from the environment each generation, or horizontally transmitted, and (ii) are defined by interactions at the interface of their cellular boundaries, i.e., extracellular symbiotic associations. As with the use of models in other fields of biology where complexity is daunting (e.g., developmental biology or brain circuitry), each model has its strengths and weaknesses, i.e., no one model system will provide easy access to all the questions defining what is conserved in cell-cell interactions in symbiosis and what creates diversity within such partnerships. Rather, as discussed here, the more models explored, the richer our understanding of these associations is likely to be.

LOAD NEXT 100 CITATIONS

ESP Quick Facts

ESP Origins

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

ESP Support

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

ESP Rationale

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

ESP Goal

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

ESP Usage

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

ESP Content

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

ESP Help

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

ESP Plans

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

Electronic Scholarly Publishing
961 Red Tail Lane
Bellingham, WA 98226

E-mail: RJR8222 @ gmail.com

Papers in Classical Genetics

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

Digital Books

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

Timelines

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

Biographies

Biographical information about many key scientists.

Selected Bibliographies

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

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