Dietary Bacillus velezensis T23 fermented products supplementation improves growth, hepatopancreas and intestine health of Litopenaeus vannamei.

This study aimed to elucidate the effects of dietary fermented products of Bacillus velezensis T23 on the growth, immune response and gut microbiota in Pacific white shrimp (Litopenaeus vannamei). Shrimp were fed with diets containing fermentation products of B. velezensis T23 at levels of (0, 0.05, 0.1, 0.2, 0.3, 0.4, and 0.5 g/kg) for 4 weeks, to assess the influence on shrimp growth. The results showed that 0.3 and 0.4 g/kg T23 supplementation improved shrimp growth and feed utilization. Based on these results we selected these three diets (Control, 0.3T23 and 0.4T23) to assess the effect on immune response and gut microbiota of shrimp. Compared with the control, the 0.3T23 and 0.4T23 groups enhanced lipase and α-amylase activities in the gut significantly. Moreover, the 0.4T23 group decreased TAG and MDA levels in hepatopancreas, ALT and AST levels of serum significantly (P < 0.05). In hepatopancreas, CAT and SOD activities were improved observably and the MDA content was reduced markedly in both T23 groups. The expressions of antimicrobial related genes, Cru and peroxinectin in the 0.3T23 group, and proPO and peroxinectin in the 0.4T23 group were up-regulated remarkably (P < 0.05). Moreover, hepatopancreas of shrimp fed with a diet amended with T23 showed a significant down-regulated expression of nf-kb and tnf-α genes, while expressions of tgf-ß was considerably up-regulated. Furthermore, serum LPS and LBP contents were reduced markedly in T23 groups. Intestinal SOD and CAT were noteworthy higher in T23 groups (P < 0.05). In the intestine of shrimp fed on the diet enriched with T23 the expression of nf-κb and tnf-α exhibited markedly down-regulated, whereas hif1α was up-regulated (P < 0.05). Besides, in the intestine of shrimp grouped under T23, Cru and peroxinectin genes were markedly up-regulated (P < 0.05). Dietary 0.3 g/kg T23 also upregulated the ratio of Rhodobacteraceae to Vibrionaceae in the gut of the shrimp. Taken together, the inclusion of B. velezensis T23 in the diet of shrimp enhanced the growth and feed utilization, enhanced hepatopancreas and intestine health.

Effects of replacing fishmeal with soybean meal on the immune and antioxidant capacity, and intestinal metabolic functions of red swamp crayfish Procambarus clarkii.

Excess utilization of plant protein sources in animal feed has been found to adversely affect the antioxidant properties and immunity of animals. While the role of gut microbes in plant protein-induced inflammation has been identified in various models, the specific mechanisms regulating gut microbes in crustaceans remain unclear. Accordingly, this study was designed to investigate the effects of replacing fishmeal with soybean meal (SM) on the hepatopancreas antioxidant and immune capacities, and gut microbial functions of crayfish, as well as the potential microbial regulatory mechanisms. 750 crayfish (4.00 g) were randomly divided into five groups: SS0, SS25, SS50, SS75, and SS100, and fed diets with different levels of soybean meal substituted for fishmeal for six weeks. High SM supplementation proved detrimental to maintaining hepatopancreas health, as indicated by an increase in hemolymph MDA content, GPT, and GOT activities, the observed rupture of hepatopancreas cell basement membranes, along with the decreased number of hepatopancreatic F cells. Moreover, crayfish subjected to high SM diets experienced obvious inflammation in hepatopancreas, together with up-regulated mRNA expression levels of nfkb, alf, and tlr (p<0.05), whereas the lzm mRNA expression level exhibited the highest value in the SS25 group. Furthermore, hepatopancreas antioxidant properties highly attenuated by the level of dietary SM substitution levels, as evidenced by the observed increase in MDA content (p<0.05), decrease in GSH content (p<0.05), and inhabitation of SOD, CAT, GPx, and GST activities (p<0.05), along with down-regulated hepatopancreas cat, gpx, gst, and mmnsod mRNA expression levels via inhibiting nrf2/keap1 pathway. Functional genes contributing to metabolism identified that high SM diets feeding significantly activated lipopolysaccharide biosynthesis, revealing gut dysfunction acted as the cause of inflammation. The global microbial co-occurrence network further indicated that the microbes contributing more to serum indicators and immunity were in module eigengene 17 (ME17). A structural equation model revealed that the genes related to alf directly drove the serum enzyme activities through microbes in ME17, with OTU399 and OTU533 identified as major biomarkers and classified into Proteobacteria that secrete endotoxins. To conclude, SM could replace 25 % of fishmeal in crayfish diets without negatively affecting immunity, and antioxidant capacity. Excessive SM levels contributed to gut dysfunction and weakened the innate immune system of crayfish.

Integration of transcriptome, gut microbiota, and physiology reveals toxic responses of the red claw crayfish (Cherax quadricarinatus) to imidacloprid.

Imidacloprid enters the water environment through rainfall and causes harm to aquatic crustaceans. However, the potential chronic toxicity mechanism of imidacloprid in crayfish has not been comprehensively studied. In this study, red claw crayfish (Cherax quadricarinatus) were exposed to 11.76, 35.27, or 88.17 µg/L imidacloprid for 30 days, and changes in the physiology and biochemistry, gut microbiota, and transcriptome of C. quadricarinatus and the interaction between imidacloprid, gut microbiota, and genes were studied. Imidacloprid induced oxidative stress and decreased growth performance in crayfish. Imidacloprid exposure caused hepatopancreas damage and decreased serum immune enzyme activity. Hepatopancreatic and plasma acetylcholine decreased significantly in the 88.17 µg/L group. Imidacloprid reduced the diversity of the intestinal flora, increased the abundance of harmful flora, and disrupted the microbiota function. Transcriptomic analysis showed that the number of up-and-down-regulated differentially expressed genes (DEGs) increased significantly with increasing concentrations of imidacloprid. DEG enrichment analyses indicated that imidacloprid inhibits neurotransmitter transduction and immune responses and disrupts energy metabolic processes. Crayfish could alleviate imidacloprid stress by regulating antioxidant and detoxification-related genes. A high correlation was revealed between GST, HSPA1s, and HSP90 and the composition of gut microorganisms in crayfish under imidacloprid stress. This study highlights the negative effects and provides detailed sequencing data from transcriptome and gut microbiota to enhance our understanding of the molecular toxicity of imidacloprid in crustaceans.

Two hexokinases of the shrimp Penaeus (Litopenaeus) vannamei are differentially expressed during oxygen limited conditions.

The white shrimp Penaeus (Litopenaeus) vannamei is the most cultivated shrimp worldwide. Compared to other shrimp species, it has higher resistance to adverse conditions. During hypoxia, the shrimp reduces oxygen consumption and adjusts energy metabolism via anaerobic glycolysis, among other strategies. Hexokinase (HK) is the first enzyme of glycolysis and a key regulation point. In mammals and other vertebrates, there are several tissue-specific HK isoforms with differences in expression and enzyme activity. In contrast, crustacean HKs have been relatively little studied. We studied the P. vannamei HK isoforms during hypoxia and reoxygenation. We cloned two HK1 sequences named HK1-long (1455 bp) and HK1-short (1302 bp), and one HK2 (1344 bp). In normoxia, total HK1 expression is higher in hepatopancreas, while HK2 is higher in gills. Severe hypoxia (1 mg/L of DO) after 12 h exposure and 1 h of reoxygenation increased HK1 expression in both organs, but HK2 expression changed differentially. In hepatopancreas, HK2 expression increased in 6 and 12 h of hypoxia but diminished to normoxia levels after reoxygenation. In gills, HK2 expression decreased after 12 h of hypoxia. HK activity increased in hepatopancreas after 12 h hypoxia, opposite to gills. These results indicate that shrimp HK isoforms respond to hypoxia and reoxygenation in a tissue-specific manner. Intracellular glucose levels did not change in any case, showing the shrimp ability to maintain glucose homeostasis during hypoxia.

Differential effects of oxytetracycline on detoxification and antioxidant defense in the hepatopancreas and intestine of Chinese mitten crab under cadmium stress.

This study aims to evaluate the effects of oxytetracycline (OTC) on detoxification and oxidative defense in the hepatopancreas and intestine of Chinese mitten crab (Eriocheir sinensis) under cadmium (Cd) stress. The crab was exposed to 0.6 µM Cd, 0.6 µM OTC, and 0.6 µM Cd plus 0.6 µM OTC for 42 days. Our results showed that in the intestine, OTC alone enhanced protein carboxylation (PC) and malondialdehyde (MDA) contents, which was associated with the increased OTC accumulation. Compared to Cd alone, Cd plus OTC increased Cd and OTC contents, and reduced detoxification (i.e., glutathione (GSH) content, gene expressions of cytochrome P450 (CYP) isoforms, 7-ethoxyresorufin O-deethylase (EROD) activity, mRNA levels and activities of glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione-S-transferase (GST)), and antioxidant defense (i.e., gene expressions and activities of catalase (CAT) and superoxide dismutase (SOD)) in the intestine, leading to the increased in PC and MDA contents, suggesting that OTC had a synergistic effect on Cd-induced oxidative damage. In the hepatopancreas, although OTC alone increased OTC accumulation, it did not affect PC and MDA contents. Compared to Cd alone, Cd plus OTC reduced MDA content, which was closely related to the improvement of detoxification (i.e., GSH content, mRNA levels of CYP isoforms, EROD activity, gene expressions and activities of GPx, GR and GST), and antioxidant defense (gene expressions and activities of CAT and SOD, metallothionein content). Aryl hydrocarbon receptor (AhR) and nuclear factor E2-related factor 2 (Nrf2) transcriptional expressions were positively correlated with most detoxification- and antioxidant-related gene expressions, respectively, indicating that AhR and Nrf2 were involved in the regulation of these gene expressions. Our results unambiguously demonstrated that OTC had tissue-specific effects on Cd-induced toxicological effect in E. sinensis, which contributed to accurately evaluating Cd toxicity modulated by TCs in crab.

Next-generation neonicotinoid: The impact of cycloxaprid on the crustacean decapod Penaeus vannamei.

Cycloxaprid, a new neonicotinoid pesticide, poses ecological risks, particularly in aquatic environments, due to its unique action and environmental dispersal. This study investigated the ecotoxicological effects of various concentrations of cycloxaprid on Penaeus vannamei over 28 days. High cycloxaprid levels significantly altered shrimp physiology, as shown by changes in the hepatosomatic index and fattening. Indicators of oxidative stress, such as increased serum hemocyanin, respiratory burst, and nitric oxide, as well as decreased phenol oxidase activity, were observed. Additionally, elevated activities of lactate dehydrogenase, succinate dehydrogenase, and isocitrate dehydrogenase indicated disrupted energy metabolism in the hepatopancreas. Notably, analyses of the nervous system revealed marked disturbances in neural signaling, as evidenced by elevated acetylcholine, octopamine, and acetylcholinesterase levels. Transcriptomic analysis highlighted significant effects on gene expression and metabolic processes in the hepatopancreas and nervous system. This study demonstrated that cycloxaprid disrupts neural signaling and oxidative balance in P. vannamei, potentially affecting its growth, and provides key insights into its biochemical and transcriptomic toxicity in aquatic systems.

Concentrations, sources and health risk of bisphenols in red swamp crayfish (Procambarus clarkii) from South-Eastern China.

Bisphenol analogs (BPs) are extensively employed in commercial and industrial products and they have been found in a variety of environmental matrices and human samples. The red swamp crayfish (Procambarus clarkii) has been a trendy food in China in recent decades. However, the levels of BPs in Chinese crayfish and the associated hazards of human exposure remain unknown. Thus, in this study, the levels of eight BPs in crayfish gathered from five major provinces engaged in crayfish within the Yangtze River Basin were analyzed. Additionally, the health risks for humans by ingesting crayfish were calculated. BPs were frequently detected in crayfish tissues, indicating the wide occurrence of these chemicals. In comparison to other substitutions, BPA remains the dominant bisphenol analog. Most of the BPs were observed to accumulate in the hepatopancreas compared to the muscle, so consuming the hepatopancreas of crayfish is not recommended. With the exception of BPS, the Estimated Daily Intakes (EDIs) of the remaining BPs exceeded the Tolerable Daily Intake (TDI) specified by the European Food Safety Authority (EFSA) by a factor of 1.75-69.0. The mean hazard index (HI) values exceeded 1 for both hepatopancreas and muscle in all provinces, and the mean HI values for hepatopancreas were significantly higher than those for muscle, indicating potential health risks for local consumers.

Glycosaminoglycan lyase: A new competition between bacteria and the pacific white shrimp Litopenaeus vannamei.

Horizontal gene transfer (HGT) is an important evolutionary force in the formation of prokaryotic and eukaryotic genomes. In recent years, many HGT genes horizontally transferred from prokaryotes to eukaryotes have been reported, and most of them are present in arthropods. The Pacific white shrimp Litopenaeus vannamei, an important economic species of arthropod, has close relationships with bacteria, providing a platform for horizontal gene transfer (HGT). In this study, we analyzed bacteria-derived HGT based on a high-quality genome of L. vannamei via a homology search and phylogenetic analysis, and six HGT genes were identified. Among these six horizontally transferred genes, we found one gene (LOC113799989) that contains a bacterial chondroitinase AC structural domain and encodes an unknown glycosaminoglycan (GAG) lyase in L. vannamei. The real-time quantitative PCR results showed that the mRNA expression level of LOC113799989 was highest in the hepatopancreas and heart, and after stimulation by Vibrio parahaemolyticus, its mRNA expression level was rapidly up-regulated within 12 h. Furthermore, after injecting si-RNA and stimulation by V. parahaemolyticus, we found that the experimental group had a higher cumulative mortality rate in 48 h than the control group, indicating that the bacteria-derived GAG lyase can reduce the mortality of shrimp with respect to infection by V. parahaemolyticus and might be related to the resistance of shrimp to bacterial diseases. Our findings contribute to the study of the function of GAGs and provide new insights into GAG-related microbial pathogenesis and host defense mechanisms in arthropods.

Integrated analysis of intestinal microbiota and transcriptome reveals that a coordinated interaction of the endocrine, immune system and gut microbiota response to heat stress in Litopenaeus vannamei.

Due to the ongoing global warming, the risk of heatwaves in the oceans is continuously increasing while our understanding of the physiological response of Litopenaeus vannamei under extreme temperature conditions remains limited. Therefore, this study aimed to evaluate the physiological responses of L. vannamei under heat stress. Our results indicated that as temperature rose, the structure of intestinal and hepatopancreatic tissues was damaged sequentially. Activity of immune-related enzymes (acid phosphatase/alkaline phosphatase) initially increased before decreased, while antioxidant enzymes (superoxide dismutase and glutathione-S transferase) activity and malondialdehyde content increased with rising temperature. In addition, the total antioxidant capacity decreased with rising temperature. With the rising temperature, there was a significant increase in the expression of caspase-3, heat shock protein 70, lipopolysaccharide-induced tumor necrosis factor-α, transcriptional enhanced associate domain and yorkie in intestinal and hepatopancreatic tissues. Following heat stress, the number of potentially beneficial bacteria (Rhodobacteraceae and Gemmonbacter) increased which maintain balance and promote vitamin synthesis. Intestinal transcriptome analysis revealed 852 differentially expressed genes in the heat stress group compared with the control group. KEGG functional annotation results showed that the endocrine system was the most abundant in Organismal systems followed by the immune system. These results indicated that heat stress leads to tissue damage in shrimp, however the shrimp may respond to stress through a coordinated interaction strategy of the endocrine system, immune system and gut microbiota. This study revealed the response mechanism of L. vannamei to acute heat stress and potentially provided a theoretical foundation for future research on shrimp environmental adaptations.

Comprehensive Multi-omics Approaches Provide Insights to Summer Mortality in the Clam Meretrix petechialis.

Bivalve mass mortalities have been reported worldwide, which not only can be explained as a result of pathogen infection, but may reflect changes in environments. Although these episodes were often reported, there was limited information concerning the molecular responses to various stressors leading to summer mortality. In the present work, RNA sequencing (RNA-seq), tandem mass tagging (TMT)-based quantitative proteomics, and 16S rRNA sequencing were used to explore the natural outbreak of summer mortality in the clam Meretrix petechialis. We identified a total of 172 differentially expressed genes (DEGs) and 222 differentially expressed proteins (DEPs) in the diseased group compared to the normal group. The inconsistent expression profiles of immune DEGs/DEPs may be due to the immune dysregulation of the diseased clams. Notably, 11 solute carrier family genes were found among the top 20 down-regulated genes in the diseased group, indicating that weakened transmembrane transport ability might occur in the diseased clams. Integration analysis of transcriptomic and proteomic results showed that many metabolic processes such as "arginine and proline metabolism" and "tyrosine metabolism" were inhibited in the diseased group, suggesting metabolic inhibition. Moreover, 16S rRNA sequencing revealed that the microbial composition of clam hepatopancreas was disordered in the diseased group. The comparison of DEGs expression between the natural summer mortality event and an artificial challenge experiment involving both Vibrio infection and heat stress revealed 9/15 genes showing similar expression trends between the two conditions, suggesting that the summer mortality might be caused by a combination of high temperature and Vibrio infection. These results would deepen our understanding of summer mortality and provide candidate resistance markers for clam resistance breeding.

Proteome analysis of outer membrane vesicles from Vibrio parahaemolyticus causing acute hepatopancreatic necrosis disease.

A specific strain of Vibrio parahaemolyticus (VpAHPND) causes acute hepatopancreatic necrosis disease (AHPND), leading to significant losses in shrimp aquaculture. Outer membrane vesicles (OMVs) are naturally secreted by Gram-negative bacteria, and their significant roles in host-pathogen interactions and pathogenicity have been recognized. In the present study, OMVs were isolated from VpAHPND by differential-ultracentrifugation and used for proteomics analysis. In the Nano-HPLC-MS/MS analysis, totally 645 proteins were determined, including virulence factors, immunogenic proteins, outer membrane protein, bacterial secretory proteins, ribosomal proteins, protease, and iron regulation proteins. Furthermore, GO and KEGG annotations indicated that proteins identified in VpAHPND-OMVs are involved in metabolism, regulation of multiple biological processes, genetic information processes, immunity and more. Meanwhile, toxin proteins PirAvp and PirBvp, associated with VpAHPND pathogenicity, were also identified in the proteome of VpAHPND-OMVs. Our objective is to identify the protein composition of OMVs released by VpAHPND, analyzing the potential for cytotoxicity and immunomodulatory activity of these granule hosts. This study is crucial for understanding the roles played by bacterial-derived vesicles in the disease process, given that these vesicles carry relevant activities inherent to the bacteria that produce them.

Incidence of mud crab reovirus (MCRV) outbreak in polyculture ponds of Andhra Pradesh, south east coast of India.

Reovirus designated as Mud crab reovirus (MCRV) is associated with the mass mortalities of mud crabs resulting in significant economic loss to crab and shrimp-mud crab polyculture farmers in the Nagayalanka, Krishna district, Andhra Pradesh. The 100 % chronic mass mortalities have been attributed to the outbreak of Mud crab reovirus (MCRV) in the polyculture farms. The moribund crabs showed autotomy, discoloration of carapace, loss of appetite, slow movement and loose gills. Histopathological observations of the infected mud crabs showed an atrophied hepatopancreas, complete degeneration of tissues along with viral inclusions in hepatopancreas, gills and muscles. Further analysis using Transmission electron microscopy (TEM), showed that the viral particles had a diameter of 70 nm and exhibited a non-enveloped, icosahedral shape arranged in a crystalline manner. The virus mainly infects the connective tissue of hepatopancreas, gills, muscle and develops in the cytoplasm. RT-PCR reconfirmed the presence of reovirus in the hepatopancreas of spontaneously infected mud crab Scylla serrata. The current study shows the importance of monitoring the MCRV prevalence in polyculture farms to minimize its spread and precautionary measures can be taken by screening the brooders from the crab hatchery and stocking of wild crabs without screening should be avoided in order to prevent MCRV outbreak.

Cellular and transcriptomic response to pathogenic and non-pathogenic Vibrio parahaemolyticus strains causing acute hepatopancreatic necrosis disease (AHPND) in Litopenaeus vannamei.

The shrimp industry has historically been affected by viral and bacterial diseases. One of the most recent emerging diseases is Acute Hepatopancreatic Necrosis Disease (AHPND), which causes severe mortality. Despite its significance to sanitation and economics, little is known about the molecular response of shrimp to this disease. Here, we present the cellular and transcriptomic responses of Litopenaeus vannamei exposed to two Vibrio parahaemolyticus strains for 98 h, wherein one is non-pathogenic (VpN) and the other causes AHPND (VpP). Exposure to the VpN strain resulted in minor alterations in hepatopancreas morphology, including reductions in the size of R and B cells and detachments of small epithelial cells from 72 h onwards. On the other hand, exposure to the VpP strain is characterized by acute detachment of epithelial cells from the hepatopancreatic tubules and infiltration of hemocytes in the inter-tubular spaces. At the end of exposure, RNA-Seq analysis revealed functional enrichment in biological processes, such as the toll3 receptor signaling pathway, apoptotic processes, and production of molecular mediators involved in the inflammatory response of shrimp exposed to VpN treatment. The biological processes identified in the VpP treatment include superoxide anion metabolism, innate immune response, antimicrobial humoral response, and toll3 receptor signaling pathway. Furthermore, KEGG enrichment analysis revealed metabolic pathways associated with survival, cell adhesion, and reactive oxygen species, among others, for shrimp exposed to VpP. Our study proves the differential immune responses to two strains of V. parahaemolyticus, one pathogenic and the other nonpathogenic, enlarges our knowledge on the evolution of AHPND in L. vannamei, and uncovers unique perspectives on establishing genomic resources that may function as a groundwork for detecting probable molecular markers linked to the immune system in shrimp.

Acute Ammonia Causes Pathogenic Dysbiosis of Shrimp Gut Biofilms.

Acute ammonia exposure has detrimental effects on shrimp, but the underlying mechanisms remain to be fully explored. In the present study, we investigated the impact of acute ammonia exposure on the gut microbiota of the white shrimp Litopenaeus vannamei and its association with shrimp mortality. Exposure to a lethal concentration of ammonia for 48 h resulted in increased mortality in L. vannamei, with severe damage to the hepatopancreas. Ammonia exposure led to a significant decrease in gut microbial diversity, along with the loss of beneficial bacterial taxa and the proliferation of pathogenic Vibrio strains. A phenotypic analysis revealed a transition from the dominance of aerobic to facultative anaerobic strains due to ammonia exposure. A functional analysis revealed that ammonia exposure led to an enrichment of genes related to biofilm formation, host colonization, and virulence pathogenicity. A species-level analysis and experiments suggest the key role of a Vibrio harveyi strain in causing shrimp disease and specificity under distinct environments. These findings provide new information on the mechanism of shrimp disease under environmental changes.

Evaluation of Collagenase Activity from Crab Hepatopancreas in Different Model Systems.

The effect of Kamchatka crab hepatopancreas containing three collagenolytic isoenzymes Collagenase KK and proteinases of Streptomyces lavendulae on metabolic activity and cell death were carried out on in vitro models. It was shown that changes in the protein structure under the influence of Collagenase KK occurred earlier than under the effect of bacterial proteinases. At the same time, activity of Collagenase KK was significantly higher than that of bacterial proteinases (p<0.01). Both preparations had a pronounced time- and dose-dependent effects on metabolic activity of cells. Collagenase KK had low cytotoxic effect, and cells mainly died by apoptosis. Thus, hepatopancreas collagenase has a high activity and proapoptotic effect on cells and can be used in low concentrations for enzymatic disaggregation of tissues.

Dietary exposure to 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) induces oxidative damage promoting cell apoptosis primarily via mitochondrial pathway in the hepatopancreas of carp, Cyprinus carpio.

To investigate the mechanisms of BDE-47 on hepatotoxicity in fish, this study examined the effects of dietary exposure to BDE-47 (40 and 4000 ng/g) on carp for 42 days. The results showed that BDE-47 significantly increased carp's condition factor and hepatosomatic index. Pathological results revealed unclear hepatic cord structure, hepatocytes swelling, cellular vacuolization, and inflammatory cell infiltration in the hepatopancreas of carp. Further investigation showed that ROS levels significantly increased on days 7, 14, and 42. Moreover, the activities of antioxidant enzymes SOD, GSH, CAT, and GST increased significantly from 1 to 7 days, and the transcription levels of antioxidant enzymes CAT, Cu-Zn SOD, Mn-SOD, GST, and GPX, and antioxidant pathway genes Keap1, Nrf2, and HO-1 changed significantly at multiple time-points during the 42 days. The results of apoptosis pathway genes showed that the mitochondrial pathway genes Bax, Casp3, and Casp9 were significantly upregulated and Bcl2 was significantly downregulated, while the transcription levels of FADD and PERK were significantly enhanced. These results indicate that BDE-47 induced oxidative damage in hepatopancreas, then it promoted cell apoptosis mainly through the mitochondrial pathway. This study provides a foundation for analyzing the mechanism of hepatotoxicity induced by BDE-47 on fish.

Toxicity of three microcystin variants on the histology, physiological and metabolism of hepatopancreas and intestinal microbiota of Litopenaeus vannamei.

Microcystins (MCs) are prevalent harmful contaminants within shrimp aquaculture systems, exhibiting a diverse array of variants. Gut microbiota can engage in mutual interactions with the host through the gut-liver axis. In this study, the shrimp Litopenaeus vannamei were subjected to three different variants of MCs (LR, YR, RR) at a concentration of 1 µg/L each, and elucidated the alterations in both intestinal microbiota and hepatopancreas physiological homeostasis. The results showed that all three variants of MCs prompted histological alterations in the hepatopancreas, induced elevated levels of oxidative stress biomarkers (H2O2, T-SOD, and CAT), disturbed the transcription levels of immune-related genes (Crus, ALF, and Lys), along with an increase in apoptotic genes (Casp-3 and P53). Furthermore, the metabolic profiles of the hepatopancreas were perturbed, particularly in amino acid metabolism such as "lysine degradation" and "ß-alanine metabolism"; the mTOR and FoxO signaling were also influenced, encompassing alterations in the transcription levels of related genes. Additionally, the alterations were observed in the intestinal microbiota's diversity and composition, particularly potential beneficial bacteria (Alloprevotella, Bacteroides, Collinsella, Faecalibacterium, and Prevotellaceae UCG-001), which exhibited a positive correlation with the metabolite berberine. These findings reveal that the three MCs variants can impact the health of the shrimp by interfering with the homeostasis of intestinal microbial and hepatopancreas physiology.

MicroRNA sequencing analysis reveals immune responses in hepatopancreas of Fenneropenaeus penicillatus under white spot syndrome virus infection.

White Spot Disease is one of the most harmful diseases of the red tail shrimp, which can cause devastating economic losses due to the highest mortality up to 100% within a few days. MicroRNAs (miRNAs) are large class of small noncoding RNAs with the ability to post-transcriptionally repress the translation of target mRNAs. MiRNAs are considered to have a significant role in the innate immune response of crustaceans, particularly in relation to antiviral defense mechanisms. Numerous crustacean miRNAs have been verified to be required in host immune defense against viral infection, however, till present, the miRNAs functions of F. penicillatus defense WSSV infection have not been studied yet. Here in this study, for the first time, miRNAs involved in the F. penicillatus immune defense against WSSV infection were identified using high-throughput sequencing platform. A total of 432 miRNAs were obtained including 402 conserved miRNAs and 30 novel predicted miRNAs. Comparative analysis between the WSSV-challenged group and the control group revealed differential expression of 159 microRNAs in response to WSSV infection. Among these, 48 were up-regulated and 111 were down-regulated. Ten candidate MicroRNAs associated with immune activities were randomly selected for qRT-PCR analysis, which confirming the expression profiling observed in the MicroRNA sequencing data. As a result, most differentially expressed miRNAs were down-regulated lead to increase the expression of various target genes that mediated immune reaction defense WSSV infection, including genes related to signal transduction, Complement and coagulation cascade, Phagocytosis, and Apoptosis. Furthermore, the genes expression of the key members in Toll and Imd signaling pathways and apoptotic signaling were mediated by microRNAs to activate host immune responses including apoptosis against WSSV infection. These results will help to understand molecular defense mechanism against WSSV infection in F. penicillatus and to develop an effective WSSV defensive strategy in shrimp farming.

Assessing the ecotoxicity of florfenicol exposure at environmental levels: A case study of histology, apoptosis and microbiota in hepatopancreas of Eriocheir sinensis.

The intensification of production practices in the aquaculture industry has led to the indiscriminate use of antibiotics to combat diseases and reduce costs, which has resulted in environmental pollution, posing serious threats to aquaculture sustainability and food safety. However, the toxic effect of florfenicol (FF) exposure on the hepatopancreas of crustaceans remains unclear. Herein, by employing Chinese mitten crab (Eriocheir sinensis) as subjects to investigate the toxic effects on histopathology, oxidative stress, apoptosis and microbiota of hepatopancreas under environment-relevant (0.5 and 5 µg/L), and extreme concentrations (50 µg/L) of FF. Our results revealed that the damage of hepatopancreas tissue structure caused by FF exposure in a dose-and time-dependent manner. Combined with the increased expression of apoptosis-related genes (Caspase 3, Caspase 8, p53, Bax and Bcl-2) at mRNA and protein levels, activation of catalase (CAT) and superoxide dismutase (SOD), and malondialdehyde (MDA) accumulation, FF exposure also induced oxidative stress, and apoptosis in hepatopancreas. Interestingly, 7 days exposure triggered more pronounced toxic effect in crabs than 14 days under environment-relevant FF concentration. Integrated biomarker response version 2 (IBRv2) index indicated that 14 days FF exposure under extreme concentration has serious toxicity effect on crabs. Furthermore, 14 days exposure to FF changed the diversity and composition of hepatopancreas microbiota leading remarkable increase of pathogenic microorganism Spirochaetes following exposure to 50 µg/L of FF. Taken together, our study explained potential mechanism of FF toxicity on hepatopancreas of crustaceans, and provided a reference for the concentration of FF to be used in culture of Chinese mitten crab.

Exposure to virgin and marine incubated microparticles of biodegradable and conventional polymers modulates the hepatopancreas transcriptome of Mytilus galloprovincialis.

Biodegradable polymers have been proposed as an alternative to conventional plastics to mitigate the impact of marine litter, but the research investigating their toxicity is still in its infancy. This study evaluates the potential ecotoxicological effects of both virgin and marine-incubated microparticles (MPs), at environmentally relevant concentration (0.1 mg/l), made of different biodegradable polymers (Polycaprolactone, Mater-Bi, cellulose) and conventional polymers (Polyethylene) on Mytilus galloprovincialis by using transcriptomics. This approach is increasingly being used to assess the effects of pollutants on organisms, obtaining data on numerous biological pathways simultaneously. Whole hepatopancreas de novo transcriptome sequencing was performed, individuating 972 genes differentially expressed across experimental groups compared to the control. Through the comparative transcriptomic profiling emerges that the preponderant effect is attributable to the marine incubation of MPs, especially for incubated polycaprolactone (731 DEGs). Mater-Bi and cellulose alter the smallest number of genes and biological processes in the mussel hepatopancreas. All microparticles, regardless of their polymeric composition, dysregulated innate immunity, and fatty acid metabolism biological processes. These findings highlight the necessity of considering the interactions of MPs with the environmental factors in the marine ecosystem when performing ecotoxicological evaluations. The results obtained contribute to fill current knowledge gaps regarding the potential environmental impacts of biodegradable polymers.