Geographical, Seasonal, and Growth-Related Dynamics of Gut Microbiota in a Grapevine Pest, Apolygus spinolae (Heteroptera: Miridae).

A number of insects are associated with gut symbiotic microorganisms, wherein symbiotic partners play pivotal metabolic roles for each other such as nutrient supplementation, diet degradation, and pesticide detoxification. Despite the ecological and evolutionary importance of gut microbial communities in insects, their diversity and dynamics remain unclear in many species. The green plant bug Apolygus spinolae, a notorious grapevine pest in Japan, damages grape shoots and severely reduces grape berry yield and quality. The plant bug possesses a simple tubular gut housing ~ 104 bacteria. Here, we investigated geographic, seasonal, and growth-related dynamics of gut microbiota by high-throughput sequencing in 82 individuals (11 nymphs and 71 adults) from five locations in Hokkaido, Japan. In plant bugs, gut microbiota changed dynamically depending on region, season, and developmental stage. Among the gut bacteria, Serratia was consistently and abundantly detected and was significantly affected by seasonal changes. In addition, Caballeronia, known as a specific symbiont in some stinkbug species, was abundantly detected, especially in insects collected in late summer despite A. spinolae complete lack of midgut crypts known as symbiotic organ harboring Caballeronia in other stinkbug species. Considering their prevalence among host bug populations, it is possible these gut microorganisms play a pivotal role in the adaptation of the green plant bug to grapevine fields, although further confirmation through rearing experiments is needed.

The Sinorhizobium meliloti nitrogen-fixing symbiosis requires CbrA-dependent regulation of a DivL and CckA phosphorelay.

The cell cycle is a fundamental process involved in bacterial reproduction and cellular differentiation. For Sinorhizobium meliloti, cell cycle outcomes depend on its growth environment. This bacterium shows a tight coupling of DNA replication initiation with cell division during free-living growth. In contrast, it undergoes a novel program of endoreduplication and terminal differentiation during symbiosis within its host. While several DivK regulators at the top of its CtrA pathway have been shown to play an important role in this differentiation process, there is a lack of resolution regarding the downstream molecular activities required and whether they could be unique to the symbiosis cell cycle. The DivK kinase CbrA is a negative regulator of CtrA activity and is required for successful symbiosis. In this work, spontaneous symbiosis suppressors of ΔcbrA were identified as alleles of divL and cckA. In addition to rescuing symbiotic development, they restore wild-type cell cycle progression to free-living ΔcbrA cells. Biochemical characterization of the S. meliloti hybrid histidine kinase CckA in vitro demonstrates that it has both kinase and phosphatase activities. Specifically, CckA on its own has autophosphorylation activity, and phosphatase activity is induced by the second messenger c-di-GMP. Importantly, the CckAA373S suppressor protein of ΔcbrA has a significant loss in kinase activity, and this is predicted to cause decreased CtrA activity in vivo. These findings deepen our understanding of the CbrA regulatory pathway and open new avenues for further molecular characterization of a network pivotal to the free-living cell cycle and symbiotic differentiation of S. meliloti.IMPORTANCESinorhizobium meliloti is a soil bacterium able to form a nitrogen-fixing symbiosis with certain legumes, including the agriculturally important Medicago sativa. It provides ammonia to plants growing in nitrogen-poor soils and is therefore of agricultural and environmental significance as this symbiosis negates the need for industrial fertilizers. Understanding mechanisms governing symbiotic development is essential to either engineer a more effective symbiosis or extend its potential to non-leguminous crops. Here, we identify mutations within cell cycle regulators and find that they control cell cycle outcomes during both symbiosis and free-living growth. As regulators within the CtrA two-component signal transduction pathway, this study deepens our understanding of a regulatory network shaping host colonization, cell cycle differentiation, and symbiosis in an important model organism.

Gut fungal diversity across different life stages of the onion fly Delia antiqua.

A significant number of microorganisms inhabit the intestinal tract or the body surface of insects. While the majority of research on insect microbiome interaction has mainly focused on bacteria, of late multiple studies have been acknowledging the importance of fungi and have started reporting the fungal communities as well. In this study, high-throughput sequencing was used to compare the diversity of intestinal fungi in Delia antiqua (Diptera: Anthomyiidae) at different growth stages, and effect of differential fungi between adjacent life stages on the growth and development of D. antiqua was investigated. The results showed that there were significant differences in the α and ß diversity of gut fungal communities between two adjacent growth stages. Among the dominant fungi, genera Penicillium and Meyerozyma and family Cordycipitaceae had higher abundances. Cordycipitaceae was mainly enriched in the pupal and adult (male and female) stages, Penicillium was mainly enriched in the pupal, 2nd instar and 3rd instar larval stages, and Meyerozyma was enriched in the pupal stage. Only three fungal species were found to differ between two adjacent growth stages. These three fungal species including Fusarium oxysporum, Meyerozyma guilliermondii and Penicillium roqueforti generally inhibited the growth and development of D. antiqua, with only P. roqueforti promoting the growth and development of female insects. This study will provide theoretical support for the search for new pathogenic microorganisms for other fly pests control and the development of new biological control strategies for fly pests.

Histone deacetylase HDAC3 regulates ergosterol production for oxidative stress tolerance in the entomopathogenic and endophytic fungus Metarhizium robertsii.

Oxidative stress is encountered by fungi in almost all niches, resulting in fungal degeneration or even death. Fungal tolerance to oxidative stress has been extensively studied, but the current understanding of the mechanisms regulating oxidative stress tolerance in fungi remains limited. The entomopathogenic and endophytic fungus Metarhizium robertsii encounters oxidative stress when it infects insects and develops a symbiotic relationship with plants, and we found that host reactive oxygen species (ROSs) greatly limited fungal growth in both insects and plants. We identified a histone H3 deacetylase (HDAC3) that catalyzed the deacetylation of lysine 56 of histone H3. Deleting Hdac3 significantly reduced the tolerance of M. robertsii to oxidative stress from insects and plants, thereby decreasing fungal ability to colonize the insect hemocoel and plant roots. HDAC3 achieved this by regulating the expression of three genes in the ergosterol biosynthesis pathway, which includes the lanosterol synthase gene Las1. The deletion of Hdac3 or Las1 reduced the ergosterol content and impaired cell membrane integrity. This resulted in an increase in ROS accumulation in fungal cells that were thus more sensitive to oxidative stress. We further showed that HDAC3 regulated the expression of the three ergosterol biosynthesis genes in an indirect manner. Our work significantly advances insights into the epigenetic regulation of oxidative stress tolerance and the interactions between M. robertsii and its plant and insect hosts.IMPORTANCEOxidative stress is a common challenge encountered by fungi that have evolved sophisticated mechanisms underlying tolerance to this stress. Although fungal tolerance to oxidative stress has been extensively investigated, the current understanding of the mechanisms for fungi to regulate oxidative stress tolerance remains limited. In the model entomopathogenic and plant symbiotic fungus Metarhizium robertsii, we found that the histone H3 deacetylase HDAC3 regulates the production of ergosterol, an essential cell membrane component. This maintains the cell membrane integrity to resist the oxidative stress derived from the insect and plant hosts for successful infection of insects and development of symbiotic associates with plants. Our work provides significant insights into the regulation of oxidative stress tolerance in M. robertsii and its interactions with insects and plants.

Root symbiotic fungi improve nitrogen transfer and morpho-physiological performance in Chenopodium quinoa.

Root-associated fungal endophytes may facilitate nitrogen (N) absorption in plants, leading to benefits in photosynthesis and growth. Here, we investigated whether endophytic insect pathogenic fungi (EIPF) are capable of transferring soil N to the crop species Chenopodium quinoa. We evaluated nutrient uptake, carbon allocation, and morpho-physiological performance in C. quinoa in symbiosis with two different EIPF (Beauveria and Metarhizium) under contrasting soil N supply. A controlled experiment was conducted using two plant groups: (1) plants subjected to low N level (5 mM urea) and (2) plants subjected to high N level (15 mM urea). Plants from each group were then inoculated with different EIPF strains, either Beauveria (EIPF1+), Metarhizium (EIPF2+) or without fungus (EIPF-). Differences in N and C content, amino acids, proteins, soluble sugars, starch, glutamine synthetase, glutamate dehydrogenase, and physiological (photosynthesis, stomatal conductance, transpiration), and morphological performance between plant groups under each treatment were examined. We found that both Beauveria and Metarhizium translocated N from the soil to the roots of C. quinoa, with positive effects on photosynthesis and plant growth. These effects, however, were differentially affected by fungal strain as well as by N level. Additionally, an improvement in root C and sugar content was observed in presence of EIPF, suggesting translocation of carbohydrates from leaves to roots. Whereas both strains were equally effective in N transfer to roots, Beauveria seemed to exert less demand in C. quinoa for photosynthesis-derived carbohydrates compared to Metarhizium. Our study revealed positive effects of EIPF on N transfer and morpho-physiological performance in crops, highlighting the potential of these fungi as an alternative to chemical fertilizers in agriculture systems.

The corncobs-loaded iron nanoparticles enhanced mechanism of denitrification performance in microalgal-bacterial aggregates system when treating low COD/TN wastewater.

To improve denitrification efficiency of microalgal-bacterial aggregates (MABAs) when treating low carbon to nitrogen (C/N) ratio wastewater, CK (the biological control), C1 (untreated corncobs), C2 (alkali-treated corncobs), CFe1 (C1 loaded iron nanoparticles) and CFe2 (C2 loaded iron nanoparticles) five groups of experiments were installed under artificial light (1600 lm). After 36 h of experiment, NO3--N was almost completely converted in CFe1 following by CFe2 when the initial concentration was 60.1 mg/L, whose NO3--N conversion rates were 6.2 and 3.4 times faster than the CK group, respectively. The result showed that the corncobs-loaded iron nanoparticles (CFe1, CFe2) had the potential to promote denitrification process and the CFe1 was more effective. Meanwhile, the CFe1 and CFe2 resulted in a decreased content in extracellular polymeric substances (EPS) secretion because iron nanoparticles (Fes) promoted electron transport and alleviated the nitrate stress. Moreover, the electrochemical analysis of EPS showed that the corncobs and corncobs-loaded iron nanoparticles improved the electron transport rate and redox active substances production. The increase in electron transport activity (ETSA), adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide (NADH) also indicated that the CFe1 and CFe2 promoted microbial metabolic activity and the electron transport rate in MABAs. In addition, the CFe1 group enhanced the enrichment of Proteobacteria, Patescibacteria, Chlorophyta and Ignavibacteriae, which was contributed to the nitrogen removal performance of MABAs. In summary, the enhancement mechanism of corncobs-loaded iron nanoparticles on denitrification process of MABAs was depicted through EPS secretion, electrochemical characteristics, microbial metabolic activity and microbial community. The article provides a viable program for enhancing the denitrification performance of MABAs when treating low C/N wastewater.

Paralimibaculum aggregatum gen. nov. sp. nov. and Biformimicrobium ophioploci gen. nov. sp. nov., two novel heterotrophs from brittle star Ophioplocus japonicus.

Two novel Gram-stain-negative, strictly aerobic, halophilic and non-motile bacterial strains, designated NKW23T and NKW57T, were isolated from a brittle star Ophioplocus japonicus collected from a tidal pool in Wakayama, Japan. The results of phylogenetic analysis based on 16S rRNA gene sequences indicated that NKW23T represented a member of the family Paracoccaceae, with Limibaculum halophilum CAU 1123T as its closest relative (94.4% sequence identity). NKW57T was identified as representing a member of the family Microbulbiferaceae, with up to 94.9% sequence identity with its closest relatives. Both strains displayed average nucleotide identity (ANI) and digital DNA-DNA hybridisation (dDDH) values below the species delimitation threshold against their closest relatives. Additionally, amino acid identity (AAI) values of both strains fell below the genus-defining threshold. Phylogenetic trees based on genome sequences indicated that NKW23T formed a novel lineage, branching deeply prior to the divergence of the genera Limibaculum and Thermohalobaculum, with an evolutionary distance (ED) of 0.31-0.32, indicative of genus-level differentiation. NKW57T similarly formed a distinct lineage separate from the species of the genus Microbulbifer. The major respiratory quinones of NKW23T and NKW57T were ubiquinone-10 (Q-10) and Q-8, respectively. The genomic DNA G+C contents of NKW23T and NKW57T were 71.4 and 58.8%, respectively. On the basis of the physiological and phylogenetic characteristics, it was proposed that these strains should be classified as novel species representing two novel genera: Paralimibaculum aggregatum gen. nov., sp. nov., with strain NKW23T (=JCM 36220T=KCTC 8062T) as the type strain, and Biformimicrobium ophioploci gen. nov., sp. nov., with strain NKW57T (=JCM 36221T=KCTC 8063T) as the type strain.

Microbial bases of herbivory in beetles.

The ecological radiation of herbivorous beetles is among the most successful in the animal kingdom. It coincided with the rise and diversification of flowering plants, requiring beetles to adapt to a nutritionally imbalanced diet enriched in complex polysaccharides and toxic secondary metabolites. In this review, we explore how beetles overcame these challenges by coopting microbial genes, enzymes, and metabolites, through both horizontal gene transfer (HGT) and symbiosis. Recent efforts revealed the functional convergence governing both processes and the unique ways in which microbes continue to shape beetle digestion, development, and defense. The development of genetic and experimental tools across a diverse set of study systems has provided valuable mechanistic insights into how microbes spurred metabolic innovation and facilitated an herbivorous transition in beetles.

Rapid Loss of Nutritional Symbionts in an Endemic Hawaiian Herbivore Radiation Is Associated with Plant Galling Habit.

Insect herbivores frequently cospeciate with symbionts that enable them to survive on nutritionally unbalanced diets. While ancient symbiont gain and loss events have been pivotal for insect diversification and feeding niche specialization, evidence of recent events is scarce. We examine the recent loss of nutritional symbionts (in as little as 1 MY) in sap-feeding Pariaconus, an endemic Hawaiian insect genus that has undergone adaptive radiation, evolving various galling and free-living ecologies on a single host-plant species, Metrosideros polymorpha within the last ∼5 MY. Using 16S rRNA sequencing, we investigated the bacterial microbiomes of 19 Pariaconus species and identified distinct symbiont profiles associated with specific host-plant ecologies. Phylogenetic analyses and metagenomic reconstructions revealed significant differences in microbial diversity and functions among psyllids with different host-plant ecologies. Within a few millions of years, Pariaconus species convergently evolved the closed-gall habit twice. This shift to enclosed galls coincided with the loss of the Morganella-like symbiont that provides the essential amino acid arginine to free-living and open-gall sister species. After the Pariaconus lineage left Kauai and colonized younger islands, both open- and closed-gall species lost the Dickeya-like symbiont. This symbiont is crucial for synthesizing essential amino acids (phenylalanine, tyrosine, and lysine) as well as B vitamins in free-living species. The recurrent loss of these symbionts in galling species reinforces evidence that galls are nutrient sinks and, combined with the rapidity of the evolutionary timeline, highlights the dynamic role of insect-symbiont relationships during the diversification of feeding ecologies. We propose new Candidatus names for the novel Morganella-like and Dickeya-like symbionts.

Nitrogen fixation and fertilization have similar effects on biomass allocation in nitrogen-fixing plants.

Plants adjust their allocation to different organs based on nutrient supply. In some plant species, symbioses with nitrogen-fixing bacteria that live in root nodules provide an alternate pathway for nitrogen acquisition. Does access to nitrogen-fixing bacteria modify plants' biomass allocation? We hypothesized that access to nitrogen-fixing bacteria would have the same effect on allocation to aboveground versus belowground tissues as access to plentiful soil nitrogen. To test this hypothesis and related hypotheses about allocation to stems versus leaves and roots versus nodules, we conducted experiments with 15 species of nitrogen-fixing plants in two separate greenhouses. In each, we grew seedlings with and without access to symbiotic bacteria across a wide gradient of soil nitrogen supply. As is common, uninoculated plants allocated relatively less biomass belowground when they had more soil nitrogen. As we hypothesized, nitrogen fixation had a similar effect as the highest level of fertilization on allocation aboveground versus belowground. Both nitrogen fixation and high fertilization led to ~10% less biomass allocated belowground (~10% more aboveground) than the uninoculated, lowest fertilization treatment. Fertilization reduced allocation to nodules relative to roots. The responses for allocation of aboveground tissues to leaves versus stems were not as consistent across greenhouses or species as the other allocation trends, though more nitrogen fixation consistently led to relatively more allocation to leaves when soil nitrogen supply was low. Synthesis: Our results suggest that symbiotic nitrogen fixation causes seedlings to allocate relatively less biomass belowground, with potential implications for competition and carbon storage in early forest development.

A novel three-part pharynx and its parallel evolution within symbiotic marine nematodes (Desmodoroidea, Stilbonematinae).

Stilbonematinae are nematodes commonly found in shallow marine sands. They are overgrown by a genus- and species-specific coat of chemoautotrophic sulphur-oxidizing ectosymbiotic bacteria which profit from the vertical migration of their hosts through the chemocline by alternately gaining access to oxidizing and reducing chemical species, while in return, the host feeds on its symbionts. The subfamily exhibits a large morphological variability; e.g. the anterior pharynx is cylindrical in genera possessing a voluminous coat, but species with a bacterial monolayer possess a distinctly swollen corpus and therefore a tripartite pharynx. Since 18S-based phylogenetic analyses do not show close relationships between corpus-bearing species, we investigated the pharynx morphology using phalloidin staining in combination with confocal laser scanning microscopy, transmission electron microscopy and light microscopy in order to assess an independent evolution. The class-wide stable position of the subventral pharynx ampullae was used as a morphological marker. Ampullae are positioned at the anterior-most end of the isthmus in Cyathorobbea, further posterior in Catanema and Robbea and inside the corpus in Laxus oneistus. We therefore conclude an independent evolution of corpus enlargements within Stilbonematinae. This further suggests that pharynx morphology is driven by the volume of the symbiotic bacterial coat rather than phylogeny. Based on an existing mathematical model, an enlarged corpus should enable its bearer to ingest food in smaller quantities, in gourmet style, whereas a cylindrical pharynx would restrict its bearer to ancestral gourmand feeding. A review of pharynx types of Nematoda showed that the Stilbonematinae pharynx is substantially different compared to other tripartite pharynges. The lack of pharyngeal tubes and valves, the undivided corpus and evenly distributed nuclei in the isthmus warrant the definition of the "stilbonematoid" three-part pharynx.

Habitat quality effects on the abundance of a coral-dwelling fish across spatial scales.

Microhabitat associated fishes are expected to be negatively affected by coral reef degradation, given that many species are coral dwellers. However, the factors underlying this negative impact and the spatial scale(s) at which it occurs are poorly understood. We explored how habitat quality metrics and host preferences influence fish abundance across multiple spatial scales, using the functionally important cleaner fish Elacatinus evelynae as a study species. We surveyed fish at 10 sites in Curaçao that varied in coral cover and health. At the microhabitat scale, we found that E. evelynae group size increases on large, healthy corals and on some coral host species, namely Montastraea cavernosa. We also found that, although E. evelynae can occupy at least 10 coral host species, it selectively inhabits just three corals: M. cavernosa, Colpophyllia natans, and Diploria labrynthiformis. Scaling up to explore goby abundance along 30-m transects, we did not find a clear relationship between live coral cover and goby abundance. However, goby abundance was substantially higher at one location with elevated coral cover and a high relative abundance of E. evelynae host species. Collectively, these results confirm that E. evelynae abundance is impacted by reef health. They also indicate that the species' long-term persistence may depend on both the maintenance of healthy coral hosts and the gobies' plasticity in host preferences on changing reefscapes. Cryptobenthic fishes such as E. evelynae play a vital role in the ecosystem and understanding drivers of their abundance is important as reefs face increased degradation.

Genetic and transcriptomic analysis of the Bradyrhizobium T3SS-triggered nodulation in the legume Aeschynomene evenia.

Some Bradyrhizobium strains nodulate certain Aeschynomene species independently of Nod factors, but thanks to their type III secretion system (T3SS). While different T3 effectors triggering nodulation (ErnA and Sup3) have been identified, the plant signalling pathways they activate remain unknown. Here, we explored the intraspecies variability in T3SS-triggered nodulation within Aeschynomene evenia and investigated transcriptomic responses that occur during this symbiosis. Furthermore, Bradyrhizobium strains having different effector sets were tested on A. evenia mutants altered in various symbiotic signalling genes. We identified the A. evenia accession N21/PI 225551 as appropriate for deciphering the T3SS-dependent process. Comparative transcriptomic analysis of A. evenia N21 roots inoculated with ORS3257 strain and its ∆ernA mutant revealed genes differentially expressed, including some involved in plant defences and auxin signalling. In the other A. evenia accession N76, all tested strains nodulated the AeCRK mutant but not the AeNIN and AeNSP2 mutants, indicating a differential requirement of these genes for T3SS-dependent nodulation. Furthermore, the effects of AePOLLUX, AeCCaMK and AeCYCLOPS mutations differed between the strains. Notably, ORS86 nodulated these three mutant lines and required for this both ErnA and Sup3. Taken together, these results shed light on how the T3SS-dependent nodulation process is achieved in legumes.

First records of hydroid epibionts on the introduced macroalga Gracilariaparvispora in the Mexican Pacific.

Background: The red macroalga Gracilariaparvispora is an introduced species in the Mexican Pacific. To date, there are no published studies on its sessile epibionts, including the hydrozoans and bryozoans, which are the dominant epibionts on macrophytes and of significant biological and economic interest. New information: This study provides insight into the faunal diversity of hydroids growing on G.parvispora. A total of 185 thalli from both herbarium specimens and field samples collected from five sites in La Paz Bay were revised. Each thallus size and the presence of hydroid epibionts in each thallus region were registered. Eight different hydrozoan taxa were growing on the red macroalgae, including the first recorded observation of Obeliaoxydentata in the Gulf of California. The sizes of the collected thalli were mostly under 7.0 cm, the maximum number of taxa per thallus was three and the thallus region containing the highest number of epibionts was in the middle. Significant differences were observed amongst the lengths of thalli with and without epibionts. The thalli with epibionts were larger than the thalli without epibionts. Similarly, significant differences were observed amongst the months. The pair-wise test revealed that each month exhibited distinctive epibiont taxa when compared to the others. This study highlights the lack of information on these associations. Further research is needed to understand whether introduced macroalgae can bring non-native epibiont species to an area.

Genomic insights into symbiosis and host adaptation of sponge-associated novel bacterium, Rossellomorea orangium sp. nov.

Sponge-associated microorganisms play vital roles in marine sponge ecology. This study presents a genomic investigation of Rossellomorea sp. MCCB 382, isolated from Stelletta sp., reveals insights into its adaptations and symbiotic roles. Phylogenomic study and Overall Genomic Relatedness Index (OGRI) classify MCCB 382 as a novel species, Rossellomorea orangium sp. nov. The genome encodes numerous carbohydrate metabolism enzymes (CAZymes), likely aiding nutrient cycling in the sponge host. Unique eukaryotic-like protein domains hint at potential mechanisms of symbiosis. Defense mechanisms include CRISPR, restriction modification systems, DNA phosphorothioation, toxin-antitoxin systems, and heavy metal and multidrug resistance genes, indicating adaptation to challenging marine environments. Unlike obligate mutualists, MCCB 382 shows no genome reduction. Furthermore, the presence of mobile genetic elements, horizontal gene transfer, and prophages suggest genetic versatility, implying flexible metabolic potential and capacity for rapid adaptation and symbiosis shifts. MCCB 382 possesses six biosynthetic gene clusters for secondary metabolites, including both type II and III polyketide synthases (PKS), terpenes, (NRPS), NRPS-independent-siderophore, and lassopeptide. Further genome mining using BiGScape revealed four distinct gene cluster families, T2PKS, NRPS-independent-siderophore, lasso peptide, and terpene, presenting opportunities for novel compound elucidation. Our study reveals a symbiotic lifestyle of MCCB 382 with the host sponge, highlighting symbiont factors that aid in establishing and sustaining this relationship. This is the pioneering genomic characterisation of a novel Rossellomorea sp. within the sponge Stelletta sp. holobiont.

Exploring symbiont gene expression in two echinoid-associated shrimp species under host separation.

Symbiotic relationships are omnipresent and particularly diverse in the marine world. In the Western Indian Ocean, the sea urchin Echinometra mathaei associates with two obligate ectosymbiotic shrimp species, Tuleariocaris holthuisi and Arete indicus. These shrimps are known for their host-dependent nature. T. holthuisi, for example, exhibits severe host separation syndrome, showing signs of stress and rapid mortality when isolated. Specific host pigments called spinochromes seem essential for T. holthuisi survival. Our study employs a transcriptomic approach to assess the stress induced by host separation on these shrimps. Using paired-end Illumina HiSeq technology, we analyzed transcriptomes of both species under three conditions: (i) symbionts on their host (CC), (ii) isolated symbionts in seawater (IC), and (iii) isolated symbionts in spinochrome-enriched seawater (IC + S). Sequencing revealed a total of 217,832 assembled unigenes, with an N50 value of 2061 bp. Isolated T. holthuisi showed 16.5 % DEGs (IC/CC), reduced to 8.5 % with spinochromes (IC + S/CC), both compared to the control condition (CC). Further analyses of stress-related genes show that T. holthuisi expressed stress-related genes when isolated in comparison to the control (IC/CC). Notably, heat shock proteins (HSPs) were significantly up-regulated in isolated T. holthuisi, especially without spinochromes. In contrast, A. indicus displayed differential expression of diverse genes, suggesting an adaptive micro-regulation mechanism to cope with isolation stress. This study pioneers the use of NGS in exploring the transcriptomic responses of symbiotic shrimp species, shedding some light on the molecular impact of the host-separation syndrome and chemical dependencies.

The hindgut microbiota of coconut rhinoceros beetles (Oryctes rhinoceros) in relation to their geographical populations.

The coconut rhinoceros beetle (CRB, Oryctes rhinoceros) is a palm tree pest capable of rapidly expanding its population in new territories. Previous studies identified a digestive symbiosis between CRB and its gut microbes. However, no research compared the genetic variation of CRBs with their hindgut microbiota on a global scale. This study aims to investigate the genetic divergence of CRB and the compositional variation of CRB's microbiota across different geographical locations, and explore the association between them and their predicted functional profiles and environmental data. The research reveals a distinct and consistent microbial community within local populations, but it varies across different geographical populations. The microbial functional profiles linked to the production of digestive enzymes, including cellulases and ligninases, are nonetheless globally conserved. This suggests that CRBs employ specific mechanisms to select and maintain microbes with functional benefits, contributing to host adaptability, stress tolerance, and fitness. The CRB microbial communities did not appear to recapitulate the genetic variation of their hosts. Rather than depend on obligate symbionts, CRBs seem to establish similar digestive associations with whatever environmentally acquired microbes are available wherever they are, aiding them in successfully establishing after invading a new location.IMPORTANCECoconut rhinoceros beetles (CRBs) are notorious pests on Arecaceae plants, posing destructive threats to countries highly reliant on coconut, oil palm, and date palm as economic crops. In the last century, CRBs have rapidly expanded their presence to territories that were once free of these beetles. The United States, for instance, has officially designated CRBs as invasive and alien pests. Given their remarkable ability to swiftly adapt to new environments, their gut microbes may play a crucial role in this process. While the microbiota of CRBs vary depending on geographical location, these beetles consistently exhibit a functionally identical digestive association with locally acquired microbes. This underscores the significance of CRB-microbe association in shaping the adaptive strategies of this agricultural pest.

Complete genome sequence of Vibrio fischeri strain H905, a planktonic isolate among squid symbiotic congeners.

Here we describe the genome sequence of Vibrio (Aliivibrio) fischeri H905, a non-symbiotic isolate from Kaneohe Bay, Hawaii. Despite its close phylogenetic relationship to squid symbiont strains, H905 is not adept at colonization. Its genome serves as a valuable comparator, illustrating the complex evolutionary dynamics within V. fischeri clades.

Gene expression plasticity governing symbiosis during natural coral bleaching.

The increasing global frequency and severity of coral bleaching events, driven by the loss of endosymbiotic algae, pose a significant threat to these vital ecosystems. However, gene expression plasticity offers a potential mechanism for rapid and effective acclimatization to environmental changes. We employed dual transcriptomics to examine the gene expression profile of Seriatopora hystrix, an ecologically important scleractinian coral, across healthy, mildly bleached, and severely bleached colonies collected from the waters of Likupang, North Sulawesi, Indonesia. Our analysis revealed that coral bleaching is associated with gene plasticity in calcium signaling and focal adhesion within coral hosts, as well as with endoplasmic reticulum stress in symbionts. Notably, we identified specific genes associated with innate immunity that were predominantly overexpressed in mildly bleached coral hosts. This overexpression implies that high expression plasticity of these key genes might contribute to bleaching resistance and the preservation of the host-symbiont relationship. Our findings offer a detailed insight into the dynamics of bleaching resistance in S. hystrix, shedding light on the variability of bleaching risks in Indonesian reefs and underscoring the coral's ability to utilize gene expression plasticity for immediate survival and potential long-term adaptation to climate changes.