Vitamin B12 produced by Cetobacterium somerae improves host resistance against pathogen infection through strengthening the interactions within gut microbiota

Exposure to polystyrene nanoplastics causes immune damage, oxidative stress and intestinal flora disruption in salamander (Andrias davidianus) larvae

The toxic effects of nanoparticles have been increasingly investigated, but there has been limited research on amphibians, especially those of conservation value. This study examined the effects of different concentrations (0, 0.04, 0.2, 1, 5 mg/L) of polystyrene nanoplastics (PS-NPs, 80 nm) on the short-term exposure (7 d) of Andrias davidianus. Results demonstrated the concentration-dependent enrichment of PS-NPs in the intestine. Histological lesions displayed increased hepatic macrophages with cellular rupture, broken intestinal villi, decreased cuprocytes and crypt depression. Antioxidant- and inflammation-related enzyme activities were analysed, and it was found that hepatic and intestinal MDA content and CAT activity were highest in the N-1 group and SOD activity was highest in the N-0.2 group (p < 0.05). AKP activity continued to decline, and iNOS activity was highest in the N-0.2 group (p < 0.05). il-10, tgf-β, bcl-w and txnl1 were significantly downregulated in the N-0.2 group, while il-6 and il-8 were markedly upregulated in the N-0.2 group (p < 0.05). Exposing to PS-NPs decreased probiotic bacteria (Cetobacterium, Akkermansia) and increased pathogenic bacteria (Lachnoclostridium). Our results suggest that NPs exposure can have deleterious effects on salamanders, which predicts that NPs contamination may lead to continued amphibian declines. Therefore, we strongly recommend that attention be paid to amphibians, especially endangered species, in the field of NPs.

Exploring the protective role of Bacillus velezensis BV1704-Y in zebrafish health and disease resistance against Aeromonas hydrophila infection

Bacillus genus, particularly Bacillus velezensis, is increasingly considered as viable alternatives to antibiotics in aquaculture due to their safety and probiotic potential. However, the specific mechanisms through which probiotic B. velezensis confers protection against Aeromonas hydrophila infection in fish remain poorly understood. This study delved into the multifaceted impacts of B. velezensis BV1704-Y on diverse facets of zebrafish health, including gut barrier function, immune response, oxidative stress, gut environment, microbiome composition, and disease resistance. Our findings demonstrate that supplementation with B. velezensis BV1704-Y significantly alleviated symptoms and reduced mortality in zebrafish infected with A. hydrophila. Furthermore, a notable reduction in the expression of pivotal immune-related genes, such as IL-1β, IL6, and TNF-α, was evident in the gut and head kidney of zebrafish upon infection. Moreover, B. velezensis BV1704-Y supplementation resulted in elevated activity levels of essential antioxidant enzymes, including SOD, CAT, and GSH, in gut tissue. Notably, B. velezensis BV1704-Y positively modulated the structure and function of the intestinal microbiome, potentially enhancing immune response and resilience in zebrafish. Specifically, supplementation with B. velezensis BV1704-Y promoted the relative abundance of beneficial bacteria, such as Cetobacterium, which showed a noteworthy negative correlation with the expression of pro-inflammatory genes and a positive correlation with gut barrier-related genes. Altogether, our study suggests that B. velezensis BV1704-Y holds promise as an effective probiotic for protecting zebrafish against A. hydrophila infection, offering potential benefits for the aquaculture industry.

Response signatures of intestinal microbiota and gene transcription of yellow catfish (Pelteobagrus fulvidraco) to Aeromonas hydrophila infection

Bacterial intestinal inflammation is a common disease of yellow catfish (Pelteobagrus fulvidraco) in high-density aquaculture. Understanding the interactions between host and intestinal bacteria is helpful to intestinal inflammatory disease control. Here, we constructed a model of intestinal inflammation after Aeromonas hydrophila infection in yellow catfish, and characterized variations in gene expression and microbiome in the gut through high-throughput sequencing. Furthermore, host gene-microbiome interactions were identified. Histology observation showed disordered distribution of columnar epithelial cells and decrease of goblet cells in intestine. A total of 4741 genes showed differentially expression, mostly in comparisons between 12 hpi group with each other groups respectively, including control, 24 hpi and 48 hpi groups. These genes were enriched in immune-related pathways including the IL-17 signaling pathway, triggering strong inflammatory response at the invading stage within 12 h. Subsequently, the host strengthened energy consumption by activating carbohydrate and lipid metabolism pathways to repair the intestinal mucosal immune defense line. In addition, fish with A. hydrophila infection show decreased richness of gut microbial, reduced relative abundance of probiotics including Akkermansia, and elevated pathogenic bacteria such as Plesimonas. An integrative analysis identified A. hydrophila-related genes, such as il22 and stat3, for which expression level is close associated with the shift of A. hydrophila-related bacteria relative abundance, such as Akkermansia and Cetobacterium. Aside from picturing the variations of intestine gene expression and mucosal microbiome of yellow catfish coping with A. hydrophila infection, our study probed the underlying host-microbe interactions in A. hydrophila infection induced intestinal inflammatory, providing new insights for disease control in aquaculture.

Alteration in oxidative stress markers, digestive physiology and gut microbiota of Heteropneustes fossilis and Clarias batrachus exposed to eriochrome black T

Synthetic dyes are the primary cause of water pollution in industrial regions. Azo dyes account for 60-70% of such dyes used in the textile sector due to their numerous beneficial characteristics. Nevertheless, there is a dearth of knowledge regarding the toxicity of Eriochrome Black T (EBT), a widely used azo dye in the textile industry. Therefore, the current study was designed to investigate the effect of EBT exposure on two catfish species, Heteropneustes fossilis and Clarias batrachus. Following 96 h exposure to 1, 10 and 20 mgL-1 of EBT, the MDA content and activities of SOD, CAT and GR exhibited a rising trend. However, as the concentration of EBT increased in both species, GPx showed decreased activity. EBT exposure also altered gut morphometry as well as the three main digestive enzymes activity (increase in lipase and trypsin activity, while decrease in amylase activity). In addition, the exposure of EBT had a significant impact on the gut microbiota of both species. C. batrachus demonstrated the suppression or absence of beneficial gut commensals (Bacillus and Cetobacterium), whereas H. fossilis revealed the proliferation and appearance of beneficial commensal microbes (Bacillus, Bacteroides, Prevotella, and Megashaera). Furthermore, the expansion or absence of these microbial communities indicated that the gut microbiota of both species was involved in dye digestion, immunity and detoxification. Overall, the percent change calculation of all the selected biomarkers, together with gut microbiota analysis, indicates that C. batrachus was more vulnerable to EBT exposure than H. fossilis. The present investigation effectively demonstrated the toxic impact of EBT on fish health by employing oxidative stress markers, digestive enzymes, and the fish gut microbiota as a promising tool for screening the impact of dye exposure on digestive physiology in toxicological research.

Deciphering the gut microbiota of zebrafish, the most used fish as a biological model: A meta-analytic approach

A meta-analytic approach deciphered the taxonomic profile of the zebrafish gut microbiota at different developmental stages. Data (16S rDNA) were systematically searched in databases, selecting those with intestine samples of fish not exposed to a particular treatment or challenge (e.g., pathogens, dietetic tests, xenobiotics, etc.) and obtaining 340 samples to be processed. Results revealed marked differences between the developmental phases. Proteobacteria was the dominant phylum in the larval phase, with a relative abundance of 90%, while the rest of the phyla did not exceed 2%. Vibrio, Aeromonas, Plesiomonas, Pseudomonas, Shewanella, and Acinetobacter were the dominant genera in this phase. Transitional changes were observed after the larvae stage. Proteobacteria still registered high abundance (48%) in the juvenile phase, but Fusobacteria (40%) and Bacteriodota (5.9%) registered considerable increases. Genera, including Cetobacterium, Plesiomonas, Aeromonas, Vibrio, and Flavobacterium, dominated this stage. The phyla Proteobacteria (48%) and Fusobacteria (35%) were strongly established in the adult phase. Cetobacterium was registered as the most abundant genus, followed by Aeromonas, Acinetobacter, Plesiomonas, Vibrio, and ZOR0006 (Firmicutes; 6%). In conclusion, the composition of the intestinal microbiota of zebrafish is consistently determined by two primary phyla, Proteobacteria and Fusobacteria; however, this composition varies depending on the developmental stage. Cetobacterium and Aeromonas are the most relevant genera in juveniles and adults. Finally, these results reveal a consistent pattern of certain bacterial groups in the zebrafish microbiota that could help shape gnotobiotic models (colonized with a specific known bacterial community) or synthetic microbiota (in vitro assembly of microbes), among other approaches.

Microbiome Dynamics and Functional Composition in Coelopa frigida (Diptera, Coelopidae): Insights into Trophic Specialization of Kelp Flies

Coelopidae (Diptera), known as kelp flies, exhibit an ecological association with beached kelp and other rotting seaweeds. This unique trophic specialization necessitates significant adaptations to overcome the limitations of an algal diet. We aimed to investigate whether the flies' microbiome could be one of these adaptive mechanisms. Our analysis focused on assessing composition and diversity of adult and larval microbiota of the kelp fly Coelopa frigida. Feeding habits of the larvae of this species have been subject of numerous studies, with debates whether they directly consume kelp or primarily feed on associated bacteria. By using a 16S rRNA metabarcoding approach, we found that the larval microbiota displayed considerably less diversity than adults, heavily dominated by only four operational taxonomic units (OTUs). Phylogenetic placement recovered the most dominant OTU of the larval microbiome, which is the source of more than half of all metabarcoding sequence reads, as an undescribed genus of Orbaceae (Gammaproteobacteria). Interestingly, this OTU is barely found among the 15 most abundant taxa of the adult microbiome, where it is responsible for less than 2% of the metabarcoding sequence reads. The other three OTUs dominating the larval microbiome have been assigned as Psychrobacter (Gammaproteobacteria), Wohlfahrtiimonas (Gammaproteobacteria), and Cetobacterium (Fusobacteriota). Moreover, we also uncovered a distinct shift in the functional composition between the larval and adult stages, where our taxonomic profiling suggests a significant decrease in functional diversity in larval samples. Our study offers insights into the microbiome dynamics and functional composition of Coelopa frigida.

Effects of phoxim on antibacterial infection of silver carp

The efficacy of phoxim in treating bacterial sepsis in silver carp is significant, yet its underlying mechanism remains elusive. This study aimed to establish a model of Aeromonas veronii infection in silver carp and subsequently treat the infected fish with 10 μg/L phoxim. Kidney and intestine samples from silver carp were collected for transcriptome analysis and assessment of intestinal microbial composition, with the aim of elucidating the mechanism underlying the efficacy of phoxim in treating bacterial sepsis in silver carp. The results of transcriptome and intestinal microbial composition analysis of silver carp kidney indicated that A. veronii infection could up-regulate the expression of il1β, il6, nos2, ctsl, casp3 et al., which means, signifying that the kidney of silver carp would undergo inflammation, induce apoptosis, and alter the composition of intestinal microorganisms. Phoxim immersion might enhance the energy metabolism of silver carp and change its intestinal microbial composition, potentially elevating the antibacterial infection resistance of silver carp. These findings may contribute to an understanding of how phoxim can effectively treat bacterial sepsis in silver carp.

Effects of Freshwater Acidification on the Gut Microbial Community of Trachemys scripta elegans

Freshwater acidification (FA) has become a global environmental problem, posing a potential threat to freshwater ecosystems. The gut microbiota plays a crucial role in the host's response and adaptation to new environments. In this study, we investigated the changes in microbial communities in Red-eared slider (Trachemys scripta elegans) under acidic conditions to reveal the ecological impacts of acidification on freshwater turtles. The results showed that there were significant differences in β-diversity (p = 0.03), while there were no significant differences in the α-diversity of gut microbiota in T. s. elegans between the different levels of acidification (pH of 5.5, 6.5, 7.5). Both the Gut Microbiome Health Index (GMHI) and the Microbial Dysbiosis Index (MDI) exhibited significant differences when comparing environments with a pH of 5.5 to those with a pH of 6.5 (p < 0.01). A comparative analysis between pH levels of 5.5 and 6.5 also revealed substantial differences (p < 0.01). Likewise, a comparative analysis between pH levels of 6.5 and 7.5 also revealed substantial differences (p < 0.01). At the phylum level, Firmicutes, Fusobacteria, and Bacteroidota formed a major part of the gut microbial community, Fusobacteria showed significant differences in different acidity environments (p = 0.03). At the genus level, Cetobacterium, Turicibacter, unclassified Eubacteriaceae, and Anaerorhabdus_furcosa_group showed significant differences in different acidity environments. The pH reduced interactivity in the gut microbiota of T. s. elegans. In addition, LEfSe analysis and functional prediction revealed that the potentially_pathogenic and stress_tolerant functional characteristics also showed significant differences in different acidity environments. The findings underscore the pivotal role of the gut microbiota in T. s. elegans in response to freshwater acidification and provide a foundation for further exploration into the impacts of acidification on freshwater ecosystems.

Environmentally Relevant Levels of Antiepileptic Carbamazepine Altered Intestinal Microbial Composition and Metabolites in Amphibian Larvae

There is growing concern about the potential ecological risks posed by pharmaceutical residues in the aquatic environment. However, our understanding of the toxic effects of antiepileptic pharmaceuticals, such as carbamazepine (CBZ), on aquatic animal larvae is still limited. In this study, the tadpoles of the black-spotted pond frog (Pelophylax nigromaculatus) were exposed to environmentally relevant concentrations of CBZ (0.3 and 3.0 μg/L) for 30 days, and their growth, intestinal microbial composition, and metabolites were investigated to assess the potential toxic effects of CBZ in non-targeted aquatic organisms. Some tadpoles died during exposure, but there was no significant among-group difference in the survival and growth rates. CBZ exposure significantly altered the composition of tadpole intestinal microbiota. Relative abundances of some bacterial genera (e.g., Blautia, Prevotella, Bacillus, Microbacterium, etc.) decreased, while others (e.g., Paucibacter, etc.) increased in CBZ-exposed tadpoles. Interestingly, CBZ-induced alterations in some bacteria might not necessarily lead to adverse outcomes for animals. Meanwhile, small molecular intestinal metabolites related to energy metabolism, and antioxidant and anti-inflammatory activities were also altered after exposure. Taken together, environmentally relevant levels of CBZ might alter the metabolic and immune performances of amphibian larvae by modifying the abundance of some specific bacteria and the level of metabolites in their intestines, thereby potentially causing a long-term effect on their fitness.

Effects of adding Bacillus subtilis natto NTU-18 in paste feed on growth, intestinal morphology, gastrointestinal microbiota diversity, immunity, and disease resistance of Anguilla japonica glass eels

Japanese eel, Anguilla japonica, holds significant importance in Taiwanese aquaculture. With the intensification of eel farming, the impact of Edwardsiella tarda has become increasingly severe. Consequently, the abusive use of antibiotics has risen. Bacillus subtilis natto NTU-18, a strain of Bacillus with a high survival rate in feed processing, plays a crucial role in promoting intestinal health through competitive rejection, enhancing immune responses against bacterial pathogens, and improving intestinal health by modulating gastrointestinal microbiota to produce beneficial metabolites of mice and grass carp, Ctenopharyngodon idella. This study investigated the effects of different proportions (control, 0.25 %, 0.5 %, 1 %, and 2 %) of B. subtilis natto NTU-18 added to paste feed on the growth performance, intestinal morphology, and microbiota, expression of immune-related genes, and resistance to E. tarda in Japanese glass eel. The results indicated that the growth performance of all groups with B. subtilis natto NTU-18 added was significantly higher than that of the control group and did not impact the villi morphology. The expression of immune-related genes in the kidney, specifically HSP70 and SOD, was significantly higher from 0.5 % and above than the control; however, no significant differences were observed in CAT, POD, and HSP90. In the liver, significant differences were found in HSP70 and IgM above 0.25 % compared to the control group, with no significant differences in SOD, CAT, POD, and HSP90 among all groups. Additionally, intestinal microbiota analysis revealed that the 2 % additional group had significantly lower diversity than other groups, with Cetobacterium as the dominant species. The challenge test observed that the survival rates of the 0.5 % and 1 % groups were significantly higher. This research suggests that adding 0.5 % and 1 % of B. subtilis natto NTU-18 to the diet is beneficial for Japanese glass eel's immunity, growth performance, and disease resistance.

Effects of Feather Hydrolysates Generated by Probiotic Bacillus licheniformis WHU on Gut Microbiota of Broiler and Common carp

Due to the ever-increasing demand for meat, it has become necessary to identify cheap and sustainable sources of protein for animal feed. Feathers are the major byproduct of poultry industry, which are rich in hard-to-degrade keratin protein. Previously we found that intact feathers can be digested into free amino acids, short peptides, and nano-/micro-keratin particles by the strain Bacillus licheniformis WHU in water, and the resulting feather hydrolysates exhibit prebiotic effects on mice. To explore the potential utilization of feather hydrolysate in the feed industry, we investigated its effects on the gut microbiota of broilers and fish. Our results suggest that feather hydrolysates significantly decrease and increase the diversity of gut microbial communities in broilers and fish, respectively. The composition of the gut microbiota was markedly altered in both of the animals. The abundance of bacteria with potentially pathogenic phenotypes in the gut microbial community of the fish significantly decreased. Staphylococcus spp., Pseudomonas spp., Neisseria spp., Achromobacter spp. were significantly inhibited by the feather hydrolysates. In addition, feather hydrolysates significantly improved proteolytic activity in the guts of broilers and fish. In fish, the expression levels of ZO-1 and TGF-α significantly improved after administration of feather hydrolysates. The results presented here suggest that feather hydrolysates generated by B. licheniformis WHU could be an alternative protein source in aquaculture and could exert beneficial effects on fish.

Systemic metabolic depletion of gut microbiome undermines responsiveness to melanoma immunotherapy

Immunotherapy has proven to be a boon for patients battling metastatic melanoma, significantly improving their clinical condition and overall quality of life. A compelling link between the composition of the gut microbiome and the efficacy of immunotherapy has been established in both animal models and human patients. However, the precise biological mechanisms by which gut microbes influence treatment outcomes remain poorly understood. Using a robust dataset of 680 fecal metagenomes from melanoma patients, a detailed catalog of metagenome-assembled genomes (MAGs) was constructed to explore the compositional and functional properties of the gut microbiome. Our study uncovered significant findings that deepen the understanding of the intricate relationship between gut microbes and the efficacy of melanoma immunotherapy. In particular, we discovered the specific metagenomic profile of patients with favorable treatment outcomes, characterized by a prevalence of MAGs with increased overall metabolic potential and proficiency in polysaccharide utilization, along with those responsible for cobalamin and amino acid production. Furthermore, our investigation of the biosynthetic pathways of short-chain fatty acids, known for their immunomodulatory role, revealed a differential abundance of these pathways among the specific MAGs. Among others, the cobalamin-dependent Wood-Ljungdahl pathway of acetate synthesis was directly associated with responsiveness to melanoma immunotherapy.

Integrated physiological, intestinal microbiota, and metabolomic responses of adult zebrafish (Danio rerio) to subacute exposure to antimony at environmentally relevant concentrations

The available information regarding the impact of antimony (Sb), a novel environmental pollutant, on the intestinal microbiota and host health is limited. In this study, we conducted physiological characterizations to investigate the response of adult zebrafish to different environmental concentrations (0, 30, 300, and 3000 µg/L) of Sb over a period of 14 days. Biochemical and pathological changes demonstrated that Sb effectively compromised the integrity of the intestinal physical barrier and induced inflammatory responses as well as oxidative stress. Analysis of both intestinal microbial community and metabolome revealed that exposure to 0 and 30 µg/L of Sb resulted in similar microbiota structures; however, exposure to 300 µg/L altered microbial communities' composition (e.g., a decline in genus Cetobacterium and an increase in Vibrio). Furthermore, exposure to 300 µg/L significantly decreased levels of bile acids and glycerophospholipids while triggering intestinal inflammation but activating self-protective mechanisms such as antibiotic presence. Notably, even exposure to 30 µg/L of Sb can trigger dysbiosis of intestinal microbiota and metabolites, potentially impacting fish health through the "microbiota-intestine-brain axis" and contributing to disease initiation. This study provides valuable insights into toxicity-related information concerning environmental impacts of Sb on aquatic organisms with significant implications for developing management strategies.

Rationally designed probiotics prevent shrimp white feces syndrome via the probiotics-gut microbiome-immunity axis

Increasing evidence infers that some complex diseases are attributed to co-infection with multiple pathogens, such as shrimp white feces syndrome (WFS); however, there is a lack of experimental evidence to validate such causal link. This deficiency further impedes rational design of probiotics to elicit desired benefits to shrimp WFS resistance. Herein, we validated the causal roles of Vibrio fluvialis, V. coralliilyticus and V. tubiashii (in a ratio of 7:2:1) in shrimp WFS etiology, which fully satisfied Koch's postulates. Correspondingly, we precisely designed four antagonistic strains: Ruegeria lacuscaerulensis, Nioella nitratireducens, Bacillus subtilis and Streptomyces euryhalinus in a ratio of 4:3:2:1, which efficiently guarded against WFS. Dietary supplementation of the probiotics stimulated beneficial gut populations, streptomycin, short chain fatty acids, taurine metabolism potentials, network stability, tight junction, and host selection, while reducing turnover rate and average variation degree of gut microbiota, thereby facilitating ecological and mechanical barriers against pathogens. Additionally, shrimp immune pathways, such as Fcγ R-mediated phagocytosis, Toll-like receptor and RIG-I-like receptor signaling pathways conferring immune barrier, were activated by probiotics supplementation. Collectively, we establish an updated framework for precisely validating co-infection with multiple pathogens and rationally designing antagonistic probiotics. Furthermore, our findings uncover the underlying beneficial mechanisms of designed probiotics from the probiotics-gut microbiome-host immunity axis.

Vitamin D promotes the folate transport and metabolism in zebrafish (Danio rerio)

Vitamin D (VD) is a fat-soluble sterol that possesses a wide range of physiological functions. The present study aimed to evaluate the effects of VD on folate metabolism in zebrafish and further investigated the underlying mechanism. Wild-type (WT) zebrafish were fed with a diet containing 0 IU/kg VD3 or 800 IU/kg VD3 for 3 wk. Meanwhile, cyp2r1 mutant zebrafish with impaired VD metabolism was used as another model of VD deficiency. Our results showed that VD deficiency in zebrafish suppressed the gene expression of folate transporters, including reduced folate carrier (RFC) and proton-coupled folate transporter (PCFT) in the intestine. Moreover, VD influenced the gene expression of several enzymes related to cellular folate metabolism in the intestine and liver of zebrafish. Importantly, VD-deficient zebrafish contained a remarkably lower level of folate content in the liver. Notably, VD was incapable of altering folate metabolism in zebrafish when gut microbiota was depleted by antibiotic treatment. Further studies proved that gut commensals from VD-deficient fish displayed a lower capacity to produce folate than those from WT fish. Our study revealed the potential correlation between VD and folate metabolism in zebrafish, and gut microbiota played a key role in VD-regulated folate metabolism in zebrafish.NEW & NOTEWORTHY Our study has identified that VD influences intestinal uptake and transport of folate in zebrafish while also altering hepatic folate metabolism and storage. Interestingly, the regulatory effects of VD on folate transport and metabolism diminished after the gut flora was interrupted by antibiotic treatment, suggesting that the regulatory effects of VD on folate metabolism in zebrafish are most likely dependent on the intestinal flora.

Mechanism of sturgeon intestinal inflammation induced by Yersinia ruckeri and the effect of florfenicol intervention

The mechanism by which Y. ruckeri infection induces enteritis in Chinese sturgeon remains unclear, and the efficacy of drug prevention and control measures is not only poor but also plagued with numerous issues. We conducted transcriptomic and 16 S rRNA sequencing analyses to examine the differences in the intestinal tract of hybrid sturgeon before and after Y. ruckeri infection and florfenicol intervention. Our findings revealed that Y. ruckeri induced the expression of multiple inflammatory factors, including il1β, il6, and various chemokines, as well as casp3, casp8, and multiple tumor necrosis factor family members, resulting in pathological injury to the body. Additionally, at the phylum level, the relative abundance of Firmicutes and Bacteroidota increased, while the abundance of Plesiomonas and Cetobacterium decreased at the genus level, altering the composition of the intestinal flora. Following florfenicol intervention, the expression of multiple apoptosis and inflammation-related genes was down-regulated, promoting tissue repair. However, the flora became further dysregulated, increasing the risk of infection. In conclusion, our analysis of the transcriptome and intestinal microbial composition demonstrated that Y. ruckeri induces intestinal pathological damage by triggering apoptosis and altering the composition of the intestinal microbiota. Florfenicol intervention can repair pathological damage, but it also exacerbates flora imbalance, leading to a higher risk of infection. These findings help elucidate the molecular mechanism of Y. ruckeri-induced enteritis in sturgeon and evaluate the therapeutic effect of drugs on intestinal inflammation in sturgeon.

Prenatal metal exposures and childhood gut microbial signatures are associated with depression score in late childhood

BACKGROUND

Childhood depression is a major public health issue worldwide. Previous studies have linked both prenatal metal exposures and the gut microbiome to depression in children. However, few, if any, have studied their interacting effect in specific subgroups of children.

OBJECTIVES

Using an interpretable machine-learning method, this study investigates whether children with specific combinations of prenatal metals and childhood microbial signatures (cliques or groups of metals and microbes) were more likely to have higher depression scores at 9-11 years of age.

METHODS

We leveraged data from a well-characterized pediatric longitudinal birth cohort in Mexico City and its microbiome substudy (n = 112). Eleven metal exposures were measured in maternal whole blood samples in the second and third trimesters of pregnancy. The gut microbial abundances were measured at 9-11-year-olds using shotgun metagenomic sequencing. Depression symptoms were assessed using the Child Depression Index (CDI) t-scores at 9-11 years of age. We used Microbial and Chemical Exposure Analysis (MiCxA), which combines interpretable machine-learning into a regression framework to identify and estimate joint associations of metal-microbial cliques in specific subgroups. Analyses were adjusted for relevant covariates.

RESULTS

We identified a subgroup of children (11.6 % of the sample) characterized by a four-component metal-microbial clique that had a significantly high depression score (15.4 % higher than the rest) in late childhood. This metal-microbial clique consisted of high Zinc in the second trimester, low Cobalt in the third trimester, a high abundance of Bacteroides fragilis, a high abundance of Faecalibacterium prausnitzii. All combinations of cliques (two-, three-, and four-components) were significantly associated with increased log-transformed t-scored CDI (β = 0.14, 95%CI = [0.05,0.23], P < 0.01 for the four-component clique).

SIGNIFICANCE

This study offers a new approach to chemical-microbial analysis and a novel demonstration that children with specific gut microbiome cliques and metal exposures during pregnancy may have a higher likelihood of elevated depression scores.

Early-Life Fecal Transplantation from High Muscle Yield Rainbow Trout to Low Muscle Yield Recipients Accelerates Somatic Growth through Respiratory and Mitochondrial Efficiency Modulation

Previous studies conducted in our lab revealed microbial assemblages to vary significantly between high (ARS-FY-H) and low fillet yield (ARS-FY-L) genetic lines in adult rainbow trout. We hypothesized that a high ARS-FY-H donor microbiome can accelerate somatic growth in microbiome-depleted rainbow trout larvae of the ARS-FY-L line. Germ-depleted larvae of low ARS-FY-L line trout reared in sterile environments were exposed to high- or low-fillet yield-derived microbiomes starting at first feeding for 27 weeks. Despite weight-normalized diets, somatic mass was significantly increased in larvae receiving high fillet yield microbiome cocktails at 27 weeks post-hatch. RNA-seq from fish tails reveals enrichment in NADH dehydrogenase activity, oxygen carrier, hemoglobin complex, gas transport, and respiratory pathways in high fillet yield recolonized larvae. Transcriptome interrogation suggests a relationship between electron transport chain inputs and body weight assimilation, mediated by the gut microbiome. These findings suggest that microbiome payload originating from high fillet yield adult donors primarily accelerates juvenile somatic mass assimilation through respiratory and mitochondrial input modulation. Further microbiome studies are warranted to assess how increasing beneficial microbial taxa could be a basis for formulating appropriate pre-, pro-, or post-biotics in the form of feed additives and lead to fecal transplantation protocols for accelerated feed conversion and fillet yield in aquaculture.

Multi-Omics Analysis to Understand the Effects of Dietary Proanthocyanidins on Antioxidant Capacity, Muscle Nutrients, Lipid Metabolism, and Intestinal Microbiota in Cyprinus carpio

Proanthocyanidins (Pros), a natural polyphenolic compound found in grape seed and other plants, have received significant attention as additives in animal feed. However, the specific mechanism by which Pros affect fish health remains unclear. Therefore, the aim of this study was to investigate the potential effects of dietary Pro on common carp by evaluating biochemical parameters and multi-omics analysis. The results showed that Pro supplementation improved antioxidant capacity and the contents of polyunsaturated fatty acids (n-3 and n-6) and several bioactive compounds. Transcriptomic analysis demonstrated that dietary Pro caused an upregulation of the sphingolipid catabolic process and the lysosome pathway, while simultaneously downregulating intestinal cholesterol absorption and the PPAR signaling pathway in the intestines. Compared to the normal control (NC) group, the Pro group exhibited higher diversity in intestinal microbiota and an increased relative abundance of Cetobacterium and Pirellula. Furthermore, the Pro group had a lower Firmicutes/Bacteroidetes ratio and a decreased relative abundance of potentially pathogenic bacteria. Collectively, dietary Pro improved antioxidant ability, muscle nutrients, and the diversity and composition of intestinal microbiota. The regulation of lipid metabolism and improvement in muscle nutrients were linked with changes in the intestinal microbiota.

Combined Dietary Administration of Chlorella fusca and Ethanol-Inactivated Vibrio proteolyticus Modulates Intestinal Microbiota and Gene Expression in Chelon labrosus

The use of functional feeds in aquaculture is currently increasing. This study aimed to assess the combined impact of dietary green microalgae Chlorella fusca and ethanol-inactivated Vibrio proteolyticus DCF12.2 (CVP diet) on thick-lipped grey mullet (Chelon labrosus) juvenile fish. The effects on intestinal microbiota and the transcription of genes related to metabolism, stress, and the immune system were investigated after 90 days of feeding. Additionally, the fish were challenged with Aeromonas hydrophila and polyinosinic-polycytidylic acid (poly I:C) to evaluate the immune response. Microbiota analysis revealed no significant differences in alpha and beta diversity between the anterior and posterior intestinal sections of fish fed the control (CT) and CVP diets. The dominant genera varied between the groups; Pseudomonas and Brevinema were most abundant in the CVP group, whereas Brevinema, Cetobacterium, and Pseudomonas were predominant in the CT group. However, microbial functionality remained unaltered. Gene expression analysis indicated notable changes in hif3α, mhcII, abcb1, mx, and tnfα genes in different fish organs on the CVP diet. In the head kidney, gene expression variations were observed following challenges with A. hydrophila or poly I:C, with higher peak values seen in fish injected with poly I:C. Moreover, c3 mRNA levels were significantly up-regulated in the CVP group 72 h post-A. hydrophila challenge. To conclude, incorporating C. fusca with V. proteolyticus in C. labrosus diet affected the microbial species composition in the intestine while preserving its functionality. In terms of gene expression, the combined diet effectively regulated the transcription of stress and immune-related genes, suggesting potential enhancement of fish resistance against stress and infections.

Effects of Lactobacillus plantarum Postbiotics on Growth Performance, Immune Status, and Intestinal Microflora of Growing Minks

The present experiment was conducted to investigate the effects of Lactobacillus plantarum postbiotics on growth performance, immune status, and intestinal microflora of growing minks. A total of 80 minks (40 males and 40 females) were divided into four groups, each group contained 20 minks (10 males and 10 females). The minks in the four groups were fed a basal diet supplemented with 0, 0.15%, 0.3%, and 0.45% Lactobacillus plantarum postbiotics (PLP), respectively. After one week of adaptation, the experiment ran for eight weeks. The results showed that Lactobacillus plantarum postbiotics tended to have effects on average daily again (ADG) during the first 4 wk of the study (p < 0.1), and had effects on immune status (p < 0.05). Lactobacillus plantarum postbiotics also affected the abundance of intestinal bacteria at genus level (p < 0.05), but had no effects on α diversity of growing minks (p > 0.05). Compared to the minks in the control group, minks in 0.30% PLP group tended to have greater ADG, and IgA and IgM content in serum as well as SIgA content in jejunal mucosa (p < 0.05), and had less jejunal mucosal TNF-α and IL-8 levels, while minks in 0.45% PLP group had less IL-2 (p < 0.05). Compared to the control, Lactobacillus plantarum postbiotics decreased the relative abundances of Bacteroides_vulgatus and Luteimonas_sp. in male minks, and the relative abundances of Streptococcus_halotolerans in female minks (p < 0.05), respectively. Males grew faster and ate more associated with less F/G than females (p < 0.05). Males also had greater serum IgA and IgG content (p < 0.05), and males had less jejunal mucosal IL-1β, IL-8, IL-2, IL-6, IL-12, IL-10, TNF-α, and IFN-γ levels (p < 0.05). These results suggest that dietary supplementation of 0.3% postbiotics harvested from Lactobacillus plantarum could improve growth performance and immune status, and modulated the intestinal bacteria abundance of growing minks.

A review of the auditory-gut-brain axis

Hearing loss places a substantial burden on medical resources across the world and impacts quality of life for those affected. Further, it can occur peripherally and/or centrally. With many possible causes of hearing loss, there is scope for investigating the underlying mechanisms involved. Various signaling pathways connecting gut microbes and the brain (the gut-brain axis) have been identified and well established in a variety of diseases and disorders. However, the role of these pathways in providing links to other parts of the body has not been explored in much depth. Therefore, the aim of this review is to explore potential underlying mechanisms that connect the auditory system to the gut-brain axis. Using select keywords in PubMed, and additional hand-searching in google scholar, relevant studies were identified. In this review we summarize the key players in the auditory-gut-brain axis under four subheadings: anatomical, extracellular, immune and dietary. Firstly, we identify important anatomical structures in the auditory-gut-brain axis, particularly highlighting a direct connection provided by the vagus nerve. Leading on from this we discuss several extracellular signaling pathways which might connect the ear, gut and brain. A link is established between inflammatory responses in the ear and gut microbiome-altering interventions, highlighting a contribution of the immune system. Finally, we discuss the contribution of diet to the auditory-gut-brain axis. Based on the reviewed literature, we propose numerous possible key players connecting the auditory system to the gut-brain axis. In the future, a more thorough investigation of these key players in animal models and human research may provide insight and assist in developing effective interventions for treating hearing loss.