Cadmium-induced oxidative stress, histopathology, and transcriptome changes in the hepatopancreas of freshwater crayfish (Procambarus clarkii)

Membrane-bound trehalase enhances cadmium tolerance by regulating cell apoptosis in Neocaridina denticulata sinensis

Trehalase gene is mainly expressed in the digestive circulatory system for regulating energy metabolism and chitin synthesis in insects, but it is significantly expressed in gill for immunomodulation in shrimp. However, its function in regulating immunity, particularly metal resistance in crustaceans has yet to be elucidated. In this study, one Tre2 gene (NdTre2) was isolated from Neocaridina denticulata sinensis. It could bind to Cd2+ and inhibit its toxicity. Spatiotemporal expression analysis showed that the expression of NdTre2 was highest in the gill and significantly reduced at 12 h after Cd2+ stimulation. The transcriptomic analysis of the gill after NdTre2 knockdown showed that the expression of genes synthetizing 20E was up-regulated and the increased 20E could further induce apoptosis by activating the intrinsic mitochondrial pathway, exogenous death receptor-ligand pathway, and MAPK pathway. In vitro, overexpressing NdTre2 enhanced the tolerance of E. coli in Cd2+ environment. In summary, these results indicate that NdTre2 plays an essential role in regulating immunity and chitin metabolism in N. denticulata sinensis.

Insights into chlorantraniliprole exposure via activating cytochrome P450-mediated xenobiotic metabolism pathway in the Procambarus clarkii: Identification of P450 genes involved in detoxification

To investigate the impact of chlorantraniliprole on Procambarus clarkii, acute toxicity tests were performed. Results indicated that 96 h post-exposure to chlorantraniliprole (60 mg/L) led to the separation of the hepatopancreas basement membrane, causing cell swelling, rupture, and vacuolation. Moreover, acid phosphatase (ACP) and alkaline phosphatase (AKP) activities exhibited divergent trends across four concentrations of chlorantraniliprole (0, 30, 60, and 90 mg/L). Hydrogen peroxide (H2O2) and catalase (CAT) levels significantly increased, while total superoxide dismutase (T-SOD) and malonaldehyde (MDA) activities decreased, indicating oxidative stress in the hepatopancreas. A total of 276 differentially expressed genes (DEGs) were identified, with 204 up-regulated and 72 down-regulated. Out of these, 114 DEGs were successfully annotated and classified into 99 pathways, with a primary focus on the cytochrome P450-mediated xenobiotic metabolism pathway. The DEGs enriched in this pathway, along with transcriptome data, were validated using quantitative-polymerase chain reaction. This study enhances the transcriptome database of P. clarkii and provides fundamental insights into its immune defense and antioxidant mechanisms. Additionally, it lays a theoretical foundation for future research on disease prevention in P. clarkii within rice-shrimp culture systems.

Toxic mechanisms of nanoplastics exposure at environmental concentrations on juvenile red swamp crayfish (Procambarus clarkii): From multiple perspectives

Nanoplastics pollution has emerged as a global issue due to its widespread potential toxicity. This study delved in to toxic effects of nanoplastics on juvenile P. clarkii and molecular mechanisms from perspectives of growth, biochemical, histopathological analysis and transcriptome level for the first time. The findings of this study indicated that nanoplastics of different concentrations have varying influence mechanisms on juvenile P. clarkii. Nanoplastics have inhibitory effects on growth of juvenile P. clarkii, can induce oxidative stress. The biochemical analysis and transcriptome results indicated that 10 mg/L nanoplastics can activate the antioxidant defense system and non-specific immune system in juvenile P. clarkii, and affect energy metabolism and oxidative phosphorylation. While 20 mg/L and 40 mg/L have a destructive influence on the immune function in juvenile P. clarkii, leading to lipid peroxidation and oxidative damage, and induce apoptosis, can affect ion transport and osmotic pressure regulation. The findings of this study can offer foundational data for delving further into impacts of nanoplastics on crustaceans and toxicity mechanism.

Bisphenol S exposed changes in intestinal microflora and metabolomics of freshwater crayfish, Procambarus clarkii

Bisphenol S (BPS), a typical endocrine-disrupting chemical (EDC), can cause hepatopancreas damage and intestinal flora disturbance. Comprehensive studies on the mechanisms of acute toxicity in crustaceans are lacking. In this study, 16S rRNA and liquid chromatography were used to investigate intestinal microbiota and metabolites of freshwater crayfish (Procambarus clarkii). In this study, freshwater crayfish were exposed to BPS (10 µg/L and 100 µg/L). The results showed a significant decrease in catalase (CAT) and superoxide dismutase (SOD) activities after exposure to BPS, which inhibited the Nrf2-Keap1 signaling pathway and induced oxidative stress toxicity in freshwater crayfish. In addition, BPS exposure induced the structural changes of intestinal microbial in the freshwater crayfish, showing different patterns of effects. The number of potentially pathogenic bacteria increased, such as Citrobacter, Hafnia-Obesumbacterium, and RsaHf231. A total of 128 different metabolites were analyzed by LC-MS/MS. The inositol and leukotriene (LT) contents in the hepatopancreas of freshwater crayfish were significantly decreased after 10 µg/L BPS exposure, which in turn led to the accumulation of lipids causing hepatopancreas damage. In conclusion, when the concentration of BPS in the water environment exceeded 10 µg/L, the freshwater crayfish intestinal microbiota was dysbiosis and the hepatopancreas metabolism was disturbed.

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.

Assessing Metal Toxicity on Crustaceans in Aquatic Ecosystems: A Comprehensive Review

Residual concentrations of some trace elements and lightweight metals, including cadmium, copper, lead, mercury, silver, zinc, nickel, chromium, arsenic, gallium, indium, gold, cobalt, polonium, and thallium, are widely detected in aquatic ecosystems globally. Although their origin may be natural, human activities significantly elevate their environmental concentrations. Metals, renowned pollutants, threaten various organisms, particularly crustaceans. Due to their feeding habits and habitat, crustaceans are highly exposed to contaminants and are considered a crucial link in xenobiotic transfer through the food chain. Moreover, crustaceans absorb metals via their gills, crucial pathways for metal uptake in water. This review summarises the adverse effects of well-studied metals (Cd, Cu, Pb, Hg, Zn, Ni, Cr, As, Co) and synthesizes knowledge on the toxicity of less-studied metals (Ag, Ga, In, Au, Pl, Tl), their presence in waters, and impact on crustaceans. Bibliometric analysis underscores the significance of this topic. In general, the toxic effects of the examined metals can decrease survival rates by inducing oxidative stress, disrupting biochemical balance, causing histological damage, interfering with endocrine gland function, and inducing cytotoxicity. Metal exposure can also result in genotoxicity, reduced reproduction, and mortality. Despite current toxicity knowledge, there remains a research gap in this field, particularly concerning the toxicity of rare earth metals, presenting a potential future challenge.

Risk assessment of pesticide compounds: IPT and TCZ cause hepatotoxicity, activate stress pathway and affect the composition of intestinal flora in red swamp crayfish (Procambarusclarkii)

Isoprothiolane (IPT) and tricyclazole (TCZ) are widely used in rice farming and recently in combined rice-fish farming. However, co-cultured animals are affected by these pesticides. To investigate the organismal effects and toxicity of pesticides, crayfish were exposed to 0, 1, 10, or 100 ppt TCZ or IPT for 7 days. Pesticide bioaccumulation, survival rate, metabolic parameters, structure of intestinal flora, and antioxidant-, apoptosis-, and HSP-related gene expression were determined. Pesticide exposure caused bioaccumulation of IPT or TCZ in the hepatopancreas and muscles of crayfish; however, IPT bioaccumulation was higher than that of TCZ. Both groups showed significant changes in hepatopancreatic serum biochemical parameters. Mitochondrial damage and chromosomal agglutination were observed in hepatopancreatic cells exposed to 100 ppt IPT or TCZ. IPT induced more significant changes in serum biochemical parameters than TCZ. The results of intestinal flora showed that Vibro, Flavobacterium, Anaerorhabdus and Shewanella may have potential for use as a bacterial marker of TCZ and IPT. Antioxidant-, apoptosis-, and HSP-related gene expression was disrupted by pesticide exposure, and was more seriously affected by IPT. The results suggest that IPT or TCZ induce hepatopancreatic cell toxicity; however, IPT or TCZ content in dietary crayfish exposed to 1 ppt was below the food safety residue standard. The data indicated that IPT exposure may be more toxic than TCZ exposure in hepatopancreas and intestines and toxicity of organism are alleviated by activating the pathway of stress-response, providing an understanding of pesticide compounds in rice-fish farming and food safety.

The evolutionary adaptation of shrimp hemocyanin subtypes and the consequences on their structure and functions

Hemocyanin is the main respiratory protein of arthropods and is formed by hexameric and/or oligomeric subunits. Due to changes in the living environment and gene rearrangement, various hemocyanin subtypes and subunits evolved in crustaceans. This paper reviews the various hemocyanin subtypes and isoforms in shrimp and analyses published genomic data of sixteen hemocyanin family genes from Litopenaeus vannamei to explore the evolution of hemocyanin genes, subunits, and protein structure. Analysis of hemocyanin subtypes distribution and structure in various tissues was also performed and related to multiple and tissue-specific functions, i.e., immunological activity, immune signaling, phenoloxidase activity, modulation of microbiota homeostasis, and energy metabolism. The functional diversity of shrimp hemocyanin due to molecular polymorphism, transcriptional regulation, alternative splicing, degradation into functional peptides, interaction with other proteins or genes, and structural differences will also be highlighted for future research. Inferences would be drawn from other crustaceans to explain how evolution has changed the structure-function of hemocyanin and its implication for evolutionary research into the multifunctionality of hemocyanin and other related proteins in shrimp.

Exposure and Health Risk Assessment of Heavy Metal in Crayfish from the Middle and Lower Reaches of the Yangtze River

Red swamp crayfish (Procambarus clarkia) is an exposed species to heavy metals due to their lifestyle of direct contact with sediments. Based on the complete crayfish industry, we focus on the presence of heavy metals in crayfish from different circulation links, which provides a new idea for the investigation of heavy metals in food. To analyze the exposure levels of heavy metals in crayfish during aquaculture and circulation, the five elements (Cd, Pb, Hg, Cr, Cu) in crayfish from 126 sampling sites were investigated. Cultured environmental samples were collected for Spearman correlation analysis. Monte Carlo simulation was used to analyze the uncertain health risks of heavy metals in crayfish. The results indicated that the average heavy metal concentrations in crayfish were all below the limit threshold values. The hepatopancreas was the main target organ for heavy metal accumulation (Cd: 0.3132 mg/kg; Pb: 0.0258 mg/kg; Hg: 0.0072 mg/kg; Cr: 0.1720 mg/kg; Cu: 10.6816 mg/kg). The positive correlation of heavy metal content between crayfish and sediments was not significant under the crayfish-rice coculture model. The 95th HI values for adults and children ranged from 0.022 to 0.042 and 0.071 to 0.137, well below 1, indicating that heavy metals do not pose a noncarcinogenic risk to humans. The potential carcinogenic risk of Cd and Cr in crayfish should be taken seriously, as the 95th CR values for children have reached 4.299 × 10-5 and 6.509 × 10-5, respectively.

Transcriptomic analysis revealed the dynamic response mechanism to acute ammonia exposure in the ivory shell, Babylonia areolata

The ivory shell (Babylonia areolata) is an economically important shellfish in tropical and subtropical regions, but its intensive culture and biological characteristic of hiding in the sandy substrate make it highly susceptible to ammonia stress. In this study, we investigated the dynamic changes in histopathology, oxidative stress, and transcriptome of the ivory shell at different time points under high concentration (60 mg/L) ammonia exposure. With prolonged exposure to stress, vacuoles appeared in the hepatopancreas while cell volume and intercellular space increased. The activities of superoxide dismutase (SOD) and catalase (CAT) decreased significantly under high concentrations of ammonia-induced stress while malondialdehyde (MDA) levels increased significantly. Integrated analysis of differentially expressed genes (DEGs), weighted gene co-expression network analysis (WGCNA), and quantitative real-time polymerase chain reaction (qRT-PCR) revealed that lipid transport primarily contributed to maintaining cellular homeostasis during the early stage of stress (6 and 12 h). Subsequently, a significant upregulation of oxidation-reduction reactions occurred at the middle stage (24 h), leading to oxidative stress. Finally, during the later stage (48 h), metabolic decomposition provided energy for survival maintenance. Additionally, lysosome and apoptosis were identified as potential key pathways in response to acute ammonia toxicity. Overall, our findings suggest that ivory shells can respond to acute ammonia toxicity via immune and antioxidant defense mechanisms but sustained high concentrations may cause irreversible damage. This study provides valuable insights into the response mechanism of mollusks towards ammonia and serves as a data reference for breeding ammonia-tolerant varieties of ivory shells.

Effects of lead contamination on histology, antioxidant and intestinal microbiota responses in freshwater crayfish, Procambarus clarkii

The red swamp crayfish (Procambarus clarkii) is an important farming species in China and there is a high degree of overlap between the main crayfish production areas and areas contaminated with the heavy metal lead (Pb), thus putting crayfish farming at potential risk of Pb contamination. To assess the toxic effects of Pb on crayfish, in this study they were exposed to different concentrations of Pb (0, 0.1, 1, 10, 50 mg/L) for 72 h, and 0.1 mg/L represents the level of Pb in the contaminated water. Histomorphology and activities of antioxidant or immune-related enzymes suggest that the damage of Pb to the hepatopancreas and intestine was dose- and time-dependent, with the intestine being more sensitive to Pb than the hepatopancreas. Notably, after a short period (24 h) of stress at low concentrations (0.1 mg/L) of Pb, the malondialdehyde (MDA) content and antioxidant enzymes such as catalase (CAT) and glutathione peroxidase (GSH-Px) in the intestine of crayfish showed significant changes, indicating that low concentrations of Pb were also highly detrimental to crayfish. High-throughput sequencing of the intestinal microbial community indicated that Pb exposure led to a disturbance in the relative abundance of intestinal bacteria, increasing the abundance of pathogenic bacteria (Bosea, Cloacibacterium, Legionella spp.) and decreasing the abundance of potentially beneficial bacteria (Chitinibacter, Chitinilyticum, Paracoccus, Microbacterium, Demequina, and Acinetobacter spp.). In conclusion, Pb damages the hepatopancreas and intestinal barrier of crayfish, leading to the destruction of their anti-stress ability and immune response, and at the same time disrupts the homeostasis of intestinal microbes, resulting in adverse effects on the gut. This study contributed to the assessment of the ecotoxicity of the heavy metal Pb to the crustacean aquatic animals.

Sub-acute toxicity of the herbicide glufosinate-ammonium exposure in adult red swamp crayfish (Procambarus clarkii)

Glufosinateammonium (GLA) is one of the most widely used agricultural herbicides. It is frequently detected in surface waters near farmland and may pose a risk to non-target aquatic species. This study aimed to explore the toxicity of subacute GLA exposure in crayfish. Adult red swamp crayfish were exposed to GLA (0, 1, 10, and 100 mg/L) for 21 days. Bioaccumulation, oxidative stress, nonspecific immunity, and the expression of genes encoding xenobiotic detoxification-related enzymes were examined. The results showed GLA accumulation and hepatopancreatic histopathological changes (dilation of hepatic tubules and vacuolation of hepatocytes) in the exposed crayfish. GLA exposure induced ROS production, inhibited glutathione expression, and catalase activity in the crayfish hepatopancreas, as well as inhibited immunoenzyme expression (acid phosphatase, alkaline phosphatase, and lysozyme) in the hemolymph. In addition, the total hemocyte number decreased, and the proportion of hemocyte subsets changed significantly. Superoxide dismutase first increased and then decreased with increasing GLA dosage. GLA promoted the expression of biotransformation enzymes (cypb5, gst) in the hepatopancreas. Our results suggest that subacute GLA exposure caused structural damage to the hepatopancreatic tissue and decreased antioxidant capacity and non-specific immunity in crayfish. These findings provide insight into the toxicity of herbicides on non-target organisms.

Effects of cadmium exposure on metabolism, antioxidant defense, immune function, and the hepatopancreas transcriptome of Cipangopaludina cathayensis

Cadmium (Cd) is a common contaminant in aquatic environments. However, little is known about the mechanisms underlying Cd toxicity in the freshwater snail Cipangopaludina cathayensis (Heude, 1890). This study to investigate the toxic effects of Cd on the standard metabolism, antioxidant activities, immune function, and hepatopancreas transcriptome profiles of C. cathayensis. C. cathayensis was exposed to 0.25, 0.5, 1.0, or 1.5 mg/L Cd for 3 h, with results showing that Cd significantly inhibited oxygen consumption and ammonia excretion and disrupted the respiratory metabolism of C. cathayensis. In addition, the O:N ratio dropped below 7, indicating that C. cathayensis may rely exclusively on proteins as an energy source under Cd stress. To understand how Cd impacts the antioxidant activities, immune function, and transcriptional profiles, C. cathayensis were exposed to 0.5 (low exposure, L14) or 1.5 (high exposure, H14) mg/L Cd for 14 days. Our results indicate that Cd exposure leads to oxidative stress and immunosuppression, with the latter effect being larger for exposure to higher Cd concentrations. A total of 2172 differentially expressed genes (DEGs) were identified by transcriptome analysis of the hepatopancreas, of which 885 were upregulated and 1287 were downregulated. Gene ontology and KEGG analyses revealed that the DEGs in the H14 group are enriched for energy generation terms and the "oxidative phosphorylation" pathway, respectively. Therefore, up-regulation of energy metabolism may be an adaptive strategy under Cd stress. Moreover, several genes involved in antioxidant activity were downregulated, whereas genes related to reactive oxygen species generation were upregulated. In addition, many immunity-related genes were identified within the DEGs, indicating that Cd toxicity may affect immune defense. Further, DEGs in the H14 group were enriched for disease-associated pathways. Taken together, our results indicate that Cd exposure leads to metabolic disorders, oxidative stress, and immunosuppression and thus may potentially contribute to disease outbreaks.

Effects of Lipopolysaccharide and Deoxynivalenol on the Survival, Antioxidant and Immune Response, and Histopathology of Crayfish (Procambarus clarkii)

Bacterial lipopolysaccharide (LPS) in the aquatic environment has been reported to cause diseases in red swamp crayfish (Procambarus clarkii). In addition, deoxynivalenol (DON) is one of the primary mycotoxins found in aquaculture. However, the potential synergistic toxic effects of LPS and DON on crayfish are yet to be fully elucidated. In this study, crayfish were exposed to LPS (1 mg kg-1), DON (3 mg kg-1), and their combination (1 mg kg-1 LPS + 3 mg kg-1 DON, L+D) for a duration of six days. Co-exposure to LPS and DON exhibited the lowest survival rate compared to the control or individual treatments with LPS or DON alone. In the initial stage of the experiment, the combined treatment of LPS and DON showed a more pronounced up-regulation of antioxidant and immune-related enzymes in the sera compared to the other treatment groups, with a fold change ranging from 1.3 to 15. In addition, the (L+D) treatment group showed a down-regulation of immune-related genes, as well as Toll pathway-related genes in the hepatopancreas compared to LPS or DON. Moreover, the (L+D) treatment group demonstrated a 100% incidence of histopathological changes in the hepatopancreas, which were significantly more severe compared to the other three groups. In conclusion, our study provides physiological and histopathological evidence that the co-exposure to LPS and DON exerted synergistic toxic effects on crayfish. The observed effects could potentially hinder the development of the crayfish aquaculture industry in China.

Selenium alleviates biological toxicity of thiamethoxam (TMX): Bioaccumulation of TMX, organ damage, and antioxidant response of red swamp crayfish (Procambarus clarkii)

Pesticides are important for agricultural development; however, animals involved in rice-fish farming absorb the pesticides used during the farming process. Thiamethoxam (TMX) is extensively used in agriculture and is gradually occupying the market for traditional pesticides. Therefore, this study aimed to investigate whether selenomethionine (SeMet) could affect the survival rate, bioaccumulation of TMX, serum biochemical parameters, lipid peroxidation, antioxidants in the hepatopancreas, and expression of stress genes after exposure of red swamp crayfish to 10 ppt TMX for 7 days. The results showed that the survival rate significantly increased and the bioaccumulation of TMX significantly decreased with SeMet administration (P < 0.05). Furthermore, severe histological damage to the hepatopancreas of red crayfish was observed after exposure to TMX; however, this damage was alleviated after SeMet administration. SeMet also significantly reduced the TMX-induced changes in serum biochemical parameters, malondialdehyde content, and antioxidant enzyme activity in crayfish hepatopancreas (P < 0.05). Notably, analysis of the expression of 10 stress response genes showed that 0.5 mg/kg SeMet might decrease cell damage in the hepatopancreas. Consequently, our findings suggest that higher levels of TMX in crayfish may cause hepatopancreatic cell toxicity, which can be harmful to human health; however, SeMet could mitigate these effects, providing an understanding of pesticide compounds and food safety.

Toxic effects of cadmium exposure on intestinal histology, oxidative stress, microbial community, and transcriptome change in the mud crab (Scylla paramamosain)

Cadmium is one of hazardous pollutants that has a great threat to aquatic organisms and ecosystems. The intestine plays important roles in barrier function and immunity to defend against environmental stress. However, whether cadmium exposure caused the intestine injury is not well studied. Thus, the aim of this study was to explore the potential mechanisms of cadmium toxicity in the intestine of mud crab (Scylla paramamosain) via physiological, histological, microbial community, and transcriptional analyses. Mud crabs were exposed to 0, 0.01, and 0.125 mg/L cadmium. After a 21-day of cadmium exposure, 0.125 mg/L cadmium caused intestine damaged by decreasing superoxide dismutase and catalase activities, and increasing hydrogen peroxide and malondialdehyde levels. Integrated biological index analysis confirmed that the toxicity of cadmium exhibited a concentration-dependent manner. Comparative transcriptional analyses showed that the up-regulations of several genes associated with heat shock proteins, detoxification and anti-oxidant defense, and two key signaling pathways (PI3k-Akt and apoptosis) revealed an adaptive response mechanism against cadmium exposure. Transcriptomic analysis also suggested that cadmium exposure disturbed the expression of ion transport and immune-related genes, indicating that it has negative effects on the immune functions of the mud crab. Furthermore, the intestinal microbial diversity and composition were significantly influenced by cadmium exposure. The abundance of the dominant phyla Fusobacteria and Bacteroidetes significantly changed after cadmium exposure. KEGG pathway analysis demonstrated that cadmium exposure could change energy metabolism and environmental information processing. Overall, we concluded that excessive cadmium exposure could be potentially exerted adverse effects to the mud crab health by inducing oxidative damage, decreasing immune system, disrupting metabolic function, and altering intestinal microbial composition. These results provided a novel insight into the mechanism of cadmium toxicity on crustaceans.

Residue behavior of cyantraniliprole and its ecological effects on Procambarus clarkii associated with the rice-crayfish integrated system

BACKGROUND

Cyantraniliprole, a second-generation diamide insecticide, was recently introduced in China, where the rice-crayfish integrated system (RCIS) is practiced to control rice pest infestations. The aim of this study was to investigate the residue behavior of cyantraniliprole in RCIS and its potential ecological effects on nontarget Procambarus clarkii in order to recommend safe pesticide application strategies.

RESULTS

Cyantraniliprole dissipated in rice plants according to first-order kinetics, with an average half-life of 5.25 days and a dissipation rate of >95% over 28 days. The terminal cyantraniliprole residue levels in rice straw, paddy hull and brown rice were all within 0.2 mg kg^-1 , which is the China-recommended maximum residue limit. The tissues of P. clarkii accumulated and distributed cyantraniliprole in the descending order gill > hepatopancreas > intestine > muscles. Procambarus clarkii exposed to cyantraniliprole exhibited a moderate decrease in weight gain, specific growth rate and condition factor compared to the control group. Exposure of P. clarkii to cyantraniliprole caused histopathological alterations to the hepatopancreas, but the alterations were not statistically significant in the 60 g ai ha^-1 cyantraniliprole group when compared with the control group.

CONCLUSION

We suggest that 10% cyantraniliprole oil dispersion be sprayed twice at an interval of 14 days and dosage of 60 g ai ha^-1 during the growth stage of rice in RCIS. © 2023 Society of Chemical Industry.

Integrated comparative transcriptome and weighted gene co-expression network analysis provide valuable insights into the response mechanisms of crayfish (Procambarus clarkii) to copper stress

One of the significant limitations of aquaculture worldwide is the prevalence of divalent copper (Cu). Crayfish (Procambarus clarkii) are economically important freshwater species adapted to a variety of environmental stimuli, including heavy metal stresses; however, large-scale transcriptomic data of the hepatopancreas of crayfish in response to Cu stress are still scarce. Here, integrated comparative transcriptome and weighted gene co-expression network analyses were initially applied to investigate gene expression profiles of the hepatopancreas of crayfish subjected to Cu stress for different periods. As a result, 4662 significant differentially expressed genes (DEGs) were identified following Cu stress. Bioinformatics analyses revealed that the "focal adhesion" pathway was one of the most significantly upregulated response pathways following Cu stress, and seven DEGs mapped to this pathway were identified as hub genes. Furthermore, the seven hub genes were examined by quantitative PCR, and each was found to have a substantial increase in transcript abundance, suggesting a critical role of the "focal adhesion" pathway in the response of crayfish to Cu stress. Our transcriptomic data can be a good resource for the functional transcriptomics of crayfish, and these results may provide valuable insights into the molecular response mechanisms underlying crayfish to Cu stress.

Systematic toxicological analysis of the effect of salinity on the physiological stress induced by triphenyltin in Nile tilapia

Triphenyltin (TPT), a synthetic chemical, is prevalent in complex salinity areas, including estuaries and coastal regions. However, current studies on the toxicological effects of TPT relevant to the environment at different salinities are limited. In the study, biochemical, histological, and transcriptional analyses of TPT and salinity alone, or in combination, was performed on the Nile tilapia (Oreochromis niloticus) liver. Nile tilapia exhibited weakened antioxidant defenses and liver damage. Transcriptomic analysis revealed that TPT exposure primarily affected lipid metabolism and immunity; salinity exposure alone particularly affected carbohydrate metabolism; combined exposure primarily immune- and metabolic-related signaling pathways. In addition, the single exposure to TPT or salinity induced inflammatory responses by up-regulating the expression of pro-inflammatory cytokines, whereas combined exposure suppressed inflammation by down-regulating pro-inflammatory cytokine levels. These findings are beneficial to understand the negative effects of TPT exposure in Nile tilapia in the broad salinity zones and its potential defense mechanisms.

Acute toxic effects of microcystin-LR on crayfish (Procambarus clarkii): Insights from antioxidant system, histopathology and intestinal flora

To study the toxic effects of microcystin-LR (MC-LR) on crayfish, adult male Procambarus clarkii were exposed to different concentrations of MC-LR for 96 h. In the meantime, the accumulation characteristics of MC-LR and the alternations of antioxidant system, histopathology and intestinal flora of P. clarkii were investigated. The results demonstrated that the hepatopancreas, gills and intestines of P. clarkii could effectively accumulate MC-LR. Antioxidant-related genes such as Mn-sod, cat, gst, gpx, mt and hsp70 showed different expression trends in different organs to respond to MC-LR-induced oxidative stress. MC-LR led to histological changes in the hepatopancreas, gills and intestines, thus affecting their corresponding physiological functions. Additionally, the abundances of bacterial phyla including Firmicutes and Planctomycetes and genera including Dysgonomonas, Brevundimonas and Anaerorhabdus in the intestine were significantly changed after MC-LR exposure, and the disruption of intestinal flora might further cause abnormal intestinal microbial metabolism and genetics in P. clarkii. This study provides novel mechanistic insights into the toxic impacts of microcystins on aquatic crustaceans. HIGHLIGHTS: • MC-LR was significantly accumulated in the hepatopancreas, gills and intestines of P. clarkii. • MC-LR induced the differential expression of antioxidant-related genes of P. clarkii. • MC-LR caused histological alterations in the hepatopancreas, gills and intestines of P. clarkii. • MC-LR affected the intestinal microbial composition and function of P. clarkii.

Cyhalofop-butyl and pyribenzoxim-induced oxidative stress and transcriptome changes in the muscle of crayfish (Procambarus clarkii)

Cyhalofop-butyl and pyribenzoxim are commonly used herbicides in rice-crayfish co-culture fields. In actual production, weed control in paddy fields is inseparable from cyhalofop-butyl and pyribenzoxim, while its risk to P. clarkii is still unclear. The present study investigated the risk of acute and subchronic toxicity of cyhalofop-butyl and pyribenzoxim to P. clarkii. The results showed that cyhalofop-butyl and pyribenzoxim exposure for 28 days could accumulate in P. clarkii muscle and inhibit P. clarkii growth. Further research found that the malondialdehyde (MDA) level and glutathione-S-transferase (GST) activity in muscle of P. clarkii were significantly increased after exposure to cyhalofop-butyl and pyribenzoxim (4 days and 28 days), and the superoxide dismutase (SOD) and catalase (CAT) activities were significantly altered. Histological results also confirmed cyhalofop-butyl and pyribenzoxim-induced muscle damage in P. clarkii. Additionally, after 28 days exposure to 1.02 mg/L cyhalofop-butyl and 10.4 mg/L pyribenzoxim, transcriptome analysis identified 2029 and 4246 differentially expressed genes (DEGs), respectively. Exposure to 1.02 mg/L cyhalofop-butyl significantly altered metabolism-related pathways, such as drug metabolism-other enzymes, glutathione metabolism, drug metabolism-cytochrome P450, fatty acid biosynthesis and fatty acid degradation. While the pathways related to antioxidant system and nutrient substances synthesis and metabolic were significantly enriched after exposure to 10.4 mg/L pyribenzoxim. This research has significant implications for scientific and rational use of herbicides under rice-crayfish co-culture and will contribute to the development of the highly productive agricultural model.

Histopathological and transcriptomic analyses reveal the reproductive endocrine-disrupting effects of decabromodiphenyl ethane (DBDPE) in mussel Mytilus galloprovincialis

The novel brominated flame retardant DBDPE has become a widespread environmental contaminant and could affect reproductive endocrine system in vertebrates. However, information about reproductive endocrine-disrupting effects of DBDPE on invertebrates is totally unknown. In this study, mussels Mytilus galloprovincialis were exposed to 1, 10, 50, 200 and 500 μg/L DBDPE for 30 days. Histopathological and transcriptomic analyses were performed to assess the reproductive endocrine-disrupting effects of DBDPE in mussels and the potential mechanisms. DBDPE promoted the gametogenesis in mussels of both sexes according to histological observation, gender-specific gene expression (VERL and VCL) and histological morphometric parameter analysis. Transcriptomic analysis demonstrated that DBDPE suppressed the genes related to cholesterol homeostasis and transport in both sexes via different LRPs- and ABCs-mediated pathways. DBDPE also disturbed nongenomic signaling pathway including signaling cascades (GPR157-IP3-Ca²⁺) in males and secondary messengers (cGMP) in females, and subsequently altered the expression levels of reproductive genes (VMO1, ZAN, Banf1 and Hook1). Additionally, dysregulation of energy metabolism in male mussels induced by DBDPE might interfere with the reproductive endocrine system. Overall, this is the first report that DBDPE evoked reproductive endocrine-disruptions in marine mussels. These findings will provide important references for ecological risk assessment of DBDPE pollution in marine environment.

Effect of dietary Bacillus subtilis supplement on Cd toxicokinetics and Cd-induced immune and antioxidant impairment of Procambarus clarkii

Cadmium (Cd), a non-biodegradable contaminant in freshwater ecosystems, can pose a serious threat to aquatic animals at high levels. In this study, the Cd toxicokinetics and the immune and antioxidant defense were explored in Procambarus clarkii exposed to different levels of Cd (0, 0.1, 1.0 mg Cd/L) or treated with 1.0 mg Cd/L and dietary Bacillus subtilis supplementation (1 × 10⁷ cfu/g). Results from the 21-day uptake and depuration experiment revealed that Cd exposure elicited a dose- and time-dependent uptake in all crayfish tissues, and the rank order of Cd concentration was gill > hepatopancreas > exoskeleton > muscle. The one-compartment model demonstrated that gills had the highest uptake rate (k_u) value after Cd aqueous exposure and the k_u and elimination rate (k_d) values in gill, hepatopancreas, and exoskeleton of the group with 1.0 mg Cd/L were higher than those of the group at alow Cd concentration (0.1 mg Cd/L). However, B. subtilis could decrease Cd k_u and increase Cd k_d in hepatopancreas, resulting in the reduction of bioconcentration factors (BCF), steady-state concentrations (C_ss), and biological half-life (T_b1/2). A positive correlation was found between aqueous Cd concentration and the severity of hepatopancreas histopathological injury, while B. subtilis could ameliorate the pathological damage in the high Cd group. Similarly, aqueous exposure to Cd elevated malonaldehyde (MDA) content and suppressed the activities of lysozyme (LZM), acid phosphatase (ACP) in hepatopancreas and alkaline phosphatase (AKP) in hemolymph. The activities of superoxide dismutase (SOD) and catalase (CAT) in hepatopancreas were also inhibited. Nevertheless, they were all recovered with the dietary addition of B. subtilis. In conclusion, our results indicated that exposure to Cd significantly increased Cd accumulation and toxic damages in crayfish hepatopancreas, while dietary administration of B. subtilis to crayfish significantly decreased Cd accumulation and improved the immune and antioxidant defense, leading to the prevention in toxic effects of Cd.

Bioaccumulation of Cd and comparative transcriptome analysis after the antagonism of Se in the hepatopancreas of estuary mud crab (Scylla paramamosain)

Cadmium (Cd) is a heavy metal contaminant and can be toxic to environment. What's more, Selenium (Se) protects organism as heavy metal antagonist. The present study aimed to investigate whether inorganic (Na₂SeO₃) or organic (L-SeMc) Se have an effect on the Cd bioaccumulation, antioxidant and immunity of the mud crab (Scylla paramamosain) under Cd exposure. The study showed that the concentration of Cd in hepatopancreas under Cd exposure was higher than the inorganic or organic Se group (P < 0.05), notably, Cd concentration of hepatopancreas in organic Se treatment is less than that in inorganic Se treatment (P < 0.05). Furthermore, this study analyzed 28 gene expression about antioxidant and immune from transcriptome, the result indicated that L-SeMc (organic Se) can reduced intracellular ROS production and oxidative damage. Furthermore, apoptosis was enhanced after Cd exposure, but Se could protect against apoptosis via expression of cathepsin B. Consequently, Organic Se may have a better effect than inorganic Se on reducing Cd toxicity. This study could provide the molecular basis that Se might alleviate Cd toxicity and increases the understanding of the environmental contaminant on crustaceans.

Transcriptome analysis preliminary reveals the immune response mechanism of golden cuttlefish (Sepia esculenta) larvae exposed to Cd

As a well-known marine metal element, Cd can significantly affect bivalve mollusk life processes such as growth and development. However, the effects of Cd on the molecular mechanisms of the economically important cephalopod species Sepia esculenta remain unclear. In this study, S. esculenta larval immunity exposed to Cd is explored based on RNA-Seq. The analyses of GO, KEGG, and protein-protein interaction (PPI) network of 1,471 differentially expressed genes (DEGs) reveal that multiple immune processes are affected by exposure such as inflammatory reaction and cell adhesion. Comprehensive analyses of KEGG signaling pathways and the PPI network are first used to explore Cd-exposed S. esculenta larval immunity, revealing the presence of 16 immune-related key and hub genes involved in exposure response. Results of gene and pathway functional analyses increase our understanding of Cd-exposed S. esculenta larval immunity and improve our overall understanding of mollusk immune functions.

Acute thiamethoxam exposure induces hepatotoxicity and neurotoxicity in juvenile Chinese mitten crab (Eriocheir sinensis)

The similar nervous system structure between crustaceans and insects and the high-water solubility of thiamethoxam can lead to the more severe toxicity of thiamethoxam to crustaceans. However, the effects of thiamethoxam on crustaceans are unclear. Therefore, a 96-h acute toxicity test was performed to explore the hepatotoxicity and neurotoxicity effects of thiamethoxam on Chinese mitten crab (Eriocheir sinensis) at concentrations 0 µg/L, 150 µg/L and 300 µg/L. The antioxidant and detoxification systems (including phases I and II) were significantly activated after exposure of juvenile crabs to thiamethoxam for 24 h in 300 µg/L group, whereas the toxic activation effect in 150 μg/L group was delayed. Moreover, a similar pattern was observed for the transcription levels of immune-related genes. Further analysis of inflammatory signaling pathway-related genes showed that thiamethoxam exposure with 300 µg/L for 24 h may induce a pro-inflammatory response through the NF-κB pathway. In contrast, the gene expression levels in 150 µg/L group were significantly upregulated compared with 0 µg/L group after 96 h. In addition, although the acute exposure of 150 μg/L thiamethoxam did not seem to induce significant neurotoxicity, the acetylcholinesterase activity was significantly decreased in 300 μg/L group after thiamethoxam exposure for 96 h. Correspondingly, thiamethoxam exposure with 300 µg/L for 24 h resulted in significantly downregulated transcriptional levels of synaptic transmission-related genes (e.g. dopamine-, gamma-aminobutyric acid- and serotonin-related receptors). Therefore, thiamethoxam may be harmful and cause potential toxic threats such as neurotoxicity and metabolic damage to crustaceans.

Oxidative Stress of Cadmium and Lead at Environmentally Relevant Concentrations on Hepatopancreas of Macrobrachium nipponensis and Their Mixture Interactivity: Implications for Water Quality Criteria Amendment

The biotoxicity of heavy metals in water has always been the focus of ecological health research. In this study, the oxidative stress-associated toxicity of cadmium (Cd) and lead (Pb) at environmentally relevant concentrations on the hepatopancreas of Macrobrachium nipponensis was investigated based on multiple biomarker responses in a 28-day indoor exposure study. Changes in integrated biomarker responses (IBR) and their interactivity were subsequently analyzed. No dead individuals were found across any of the tested conditions. The chronic toxicity of heavy metals depended on their type and exposure time at the same concentration. At low concentrations, organisms have a regulatory capacity to cope with the excess reactive oxygen species (ROS) induced by Pb stress over time. In detail, the activity of superoxide dismutase (SOD) was inhibited by Pb stress at a high concentration as time passed. The sensitivity of metallothionein (MT) to Cd was stronger than Pb, and the potential for Cd to cause lipid peroxidation damage was higher than Pb. At the same time, Pb had a greater disturbance effect on the nervous system than Cd, especially in the early exposure stage. The contribution of Cd and Pb to the interaction effect varied dynamically with time and concentration of exposure, but mostly showed antagonism. The results of this study have important significance for guiding the diagnosis of ecological water health, the amendment of water quality criteria, and the management of wastewater discharge.

Determination of Soil Cadmium Safety Thresholds for Food Production in a Rice-Crayfish Coculture System

Previous studies have mainly focused on cadmium (Cd) contamination in conventional rice monocultures, and no research on rice-crayfish coculture has been reported. In this study, a Cd-contaminated (0−30 mg kg−1) rice-crayfish co-culture system was established by adding exogenous Cd. The results showed that the Cd concentration in each tissue of rice and each organ of crayfish increased with increasing soil Cd concentration. Specifically, the Cd concentration in each rice tissue was as follows: root > stem > leaf ≈ panicle > grain > brown rice, and the jointing and heading stages were critical periods for the rapid enrichment of Cd in the aboveground tissues of rice. The Cd concentration in each organ of crayfish was as follows: hepatopancreas > gut > gill ≈ exoskeleton > abdominal muscle. Cd was gradually enriched in the abdominal muscle after 30 days of coculture between crayfish and rice. Pearson’s correlation analysis showed that the soil’s total Cd concentration, available Cd concentration, and water Cd concentration were positively correlated with Cd content in various tissues of rice and various organs of crayfish, whereas EC and TDS in water were markedly related to rice stems, leaves, stalks, and small crayfish. According to the maximum limit of Cd in grain (0.2 mg kg−1) and crustacean aquatic products (0.5 mg kg−1) in China, the safe threshold of soil Cd for rice and crayfish under the rice-crayfish coculture system is 3.67 and 14.62 mg kg−1, respectively. Therefore, when the soil Cd concentration in the rice-crayfish coculture system exceeds 3.67 mg kg−1, the safety risk to humans through the consumption of food from this coculture system will increase. This study provides a theoretical basis for safe food production in a rice-crayfish coculture system using the established Cd pollution model.

Effects of ocean acidification and tralopyril on bivalve biomineralization and carbon cycling: A study of the Pacific Oyster (Crassostrea gigas)

The combined effects of emerging pollutants and ocean acidification (OA) on marine organisms and marine ecosystems have attracted increasing attention. However, the combined effects of tralopyril and OA on marine organisms and marine ecosystems remain unclear. In this study, Crassostrea gigas (C. gigas) were exposed to tralopyril (1 μg/L) and/or OA (PH = 7.7) for 21 days and a 14-day recovery acclimation. To investigate the stress response and potential molecular mechanisms of C. gigas to OA and tralopyril exposure alone or in combination, as well as the effects of OA and/or tralopyril on bivalve biomineralization and marine carbon cycling. The results showed that the combined toxicity was between that of acidification and tralopyril alone. Single or combined exposure activated the general stress defense responses of C. gigas mantle, affected energy metabolism and biomineralization of the organism and the carbon cycle of the marine ecosystem. Moreover, acidification-induced and tralopyril-induced toxicity showed potential recoverability at molecular and biochemical levels. This study provides a new perspective on the molecular mechanisms of tralopyril toxicity to bivalve shellfish and reveals the potential role of tralopyril and OA on marine carbon cycling.

The health risk for consumers under heavy metal scenarios: Reduce bioaccumulation of Cd in estuary mud crab (Scylla paramamosain) through the antagonism of Se

Heavy metal pollution has gained increasing attention over past years, and notably, cadmium (Cd) is a non-essential heavy metal that can be toxic to human and wildlife. Furthermore, selenium (Se) is a component of the selenoproteins and influences the toxicity of Cd in different organisms, and protect organisms as a kind of heavy metal antagonist. This study exposed mud crab to 5.0 mg/L Cd for 28 days, and investigated whether different concentrations (0.1, 0.2, 0.3 mg/kg) of selenite (Na₂SeO₃) or selenomethionine (SeMet) affect the bioaccumulation of Cd, serum biochemical index, antioxidant and stress-response genes of S. paramamosain. The results showed that the Cd concentration in Cd group was significantly higher than the organic or inorganic Se group. Serum biochemical index demonstrated that Se might relieve the damage or dysfunction of hepatopancreas caused by both Cd accumulation and toxicity. Furthermore, Se improved CAT, GPx T-AOC and SOD activity, and decreased MDA concentrations and the lipid peroxidation levels, antagonistic to Cd. Then, this study analyzed the expression of 26 stress-related genes, the results indicated that the inorganic and organic Se might reduce the damage of cell and the toxicity of heavy metals in the hepatopancreas after Cd exposure. Therefore, this study indicated that Se might alleviate Cd toxicity via the different antioxidative mechanisms, and increased the understanding of environmental toxins on estuary crustaceans.

Health risk assessment of perchlorate and chlorate in red swamp crayfish (Procambarus clarkii) in China

Perchlorate and chlorate are both strong oxidants and thyroid toxicants that are widely distributed in soil, water and human foods. The red swamp crayfish (Procambarus clarkii) is a common aquatic organism that is popular in Chinese culinary dishes. Dietary intake is the main route of human exposure to perchlorate and chlorate, though the health risks of crayfish consumption are unknown. Thus, this study investigated the quantities of perchlorate and chlorate in red swap crayfish from sampling sites in five provinces located near the Yangtze River in China, along with the associated health risks of consuming this species. Perchlorate was detected in 55.6-100 % of crayfish samples in each sampling location, and chlorate was found in 100 % of samples cross all sites. Concentrations of perchlorate in crayfish from upstream provinces (Hubei, Hunan and Jiangxi) were higher than those from downstream provinces (Anhui and Jiangsu). Perchlorate and chlorate concentrations were positively correlated in crayfish, suggesting that chlorate may be a degradation byproduct of perchlorate. The quantities of both pollutants in hepatopancreas tissue were higher than in muscle tissues (p < 0.05), such that we do not recommend ingesting crayfish hepatopancreas. Hazard quotient (HQ) values for chlorate in crayfish were <1 across all provinces, suggesting no potential health risk of chlorate exposure through crayfish consumption. However, perchlorate concentrations in crayfish from the Jiangxi province had an associated HQ value >1, suggesting potential risks for human health. These results will be useful in informing mitigation measures aimed at reducing perchlorate exposure associated with crayfish consumption.

Water hardness alleviates the stress response caused by waterborne zinc in goldfish Carassius auratus

In this study, the combined effect of waterborne Zn and water hardness on the stress response in the goldfish Carassius auratus was investigated. Goldfish were exposed to Zn concentrations of 0.5, 1.0, and 3.0 mg/L and water hardness of 90, 270, and 450 mg/L CaCO₃ for 1, 3, 7, and 14 d. After exposure, it was determined that higher the Zn concentration, the more obvious the stress response. However, the stress response reduced with increasing water hardness. An increase in the Zn concentration caused stress responses in fish according to the increase in the mRNA expressions of corticotropin-releasing hormone and adrenocorticotropic hormone and cortisol level in the hypothalamus-pituitary-interrenal axis. The expression of these factors was the highest on day 7 and decreased on day 14. Furthermore, to evaluate the stress change in the liver tissue, we analyzed alanine aminotransferase, aspartate aminotransferase, and heat shock protein 70 concentrations to determine the damage caused by Zn and the change in water hardness. Immunohistochemistry staining for Na⁺/K⁺-ATPase in the gills showed that the gill activity was inhibited by Zn, and an increase in water hardness could improve Na⁺/K⁺-ATPase. In conclusion, we found that increasing water hardness is a successful method to reduce the stress response in goldfish caused by Zn.

Does persistent organic pollutant PFOS (perfluorooctane sulfonate) negative impacts on the aquatic invertebrate organism, Astacus leptodactylus [Eschscholtz, 1823]

Highly persistent perfluorooctane sulfonate (PFOS) is an industrial fluorinated organic chemical with significant bioaccumulation and biomagnification properties. The purpose of this study was to determine the toxic effects of sublethal PFOS on the aquatic invertebrate organism, narrow-clawed crayfish [Astacus leptodactylus Eschscholtz, 1823]. The 96 h LC₅₀ value was determined as 48.81 mg/L (34.19-63.68 mg/L) with probit analysis. The sublethal experimental design was formed into four groups solvent control (DMSO, dimethyl sulphoxide), non-treated control group, and 1/10 (5 mg/L) and 1/100 (0.5 mg/L) of 96 h LC₅₀ of PFOS, and crayfish were exposed for 48 h, 7 d, and 21 d under laboratory conditions. Total haemocyte counts (THCs) decreased, while the haemolymph total antioxidant status (TAS) values increased (p < 0.05) after exposure to 0.5 and 5 mg/L PFOS for 48 h, 7 d, and 21 d. Haemolymph total oxidative stress (TOS) levels significantly increased at 5 mg/L PFOS concentration (p < 0.05). Catalase (CAT) activities increased at both concentrations after 48 h and 7 d and then returned to control levels after 21 d; whereas superoxide dismutase (SOD) and glutathione peroxidase (GPX) activities did not change in muscle tissue (p > 0.05). GPX and CAT activities decreased, but SOD activity increased in hepatopancreas tissue (p < 0.05). SOD activity at both concentrations and CAT activity at 5 mg/L PFOS exposure decreased in gill tissue, while GPX activity increased at both concentrations of 48 h and 7 d and returned to control values on day 21 of exposure. Histopathological alterations were detected in hepatopancreas and gill tissues. Lamellar deformations, epithelial hyperplasia, and haemocytic infiltrations were observed in the gill tissues, whereas tubular degeneration, tubule loss, necrosis, and lesions in the hepatopancreas tissues were the major recorded alterations. As a result, the sublethal concentrations of PFOS have toxic effects on crayfish and histologically cause tissue damage. Our findings also support a better understanding of the early toxicological effects of PFOS in freshwater ecosystems. Also, it could be concluded that A. leptodactylus is a reliable model for examining histopathological alterations and differences in enzyme activities together with the haemolymph findings in toxicology studies amid aquatic species.

Acute toxic effects of diclofenac exposure on freshwater crayfish (Procambarus clarkii): Insights from hepatopancreatic pathology, molecular regulation and intestinal microbiota

In this study, we exposed adult male crayfish (Procambarus clarkii) to different concentrations of diclofenac (DCF) for 96 h. In the meantime, we investigated the alternations of hepatopancreatic pathology, molecular regulation and intestinal microbiota of P. clarkii exposed to DCF. The results demonstrated DCF led to histological changes including epithelium vacuolization and tubule lumen dilatation in the hepatopancreas. Transcriptome sequencing analysis showed that 642 and 586 genes were differentially expressed in the hepatopancreas of P. clarkii exposed to 1 and 10 mg/L DCF, respectively. DCF could affect the functions of antioxidation, immunity and metabolism of hepatopancreas by inducing the abnormal expressions of immune- and redox-related genes. GO enrichment results demonstrated that 10 mg/L DCF exposure could modulate the processes of molting, amino sugar metabolism, protein hydrolysis and intracellular protein translocation of P. clarkii. Additionally, the abundances of bacterial families including Shewanellaceae, Bacteroidaceae, Vibrionaceae, Erysipelotrichaceae, Aeromonadaceae, Moraxellaceae, etc. in the intestine were significantly changed after DCF exposure, and the disruption of intestinal flora might further cause abnormal intestinal metabolism in P. clarkii. This study provides novel mechanistic insights into the toxic effects of anti-inflammatory drugs on aquatic crustaceans.

Mercury Induced Tissue Damage, Redox Metabolism, Ion Transport, Apoptosis, and Intestinal Microbiota Change in Red Swamp Crayfish (Procambarus clarkii): Application of Multi-Omics Analysis in Risk Assessment of Hg

As one of the most toxic elements, mercury (Hg) is a widespread toxicant in aquatic environments. Crayfish are considered suitable for indicating the impact of heavy metals on aquatic crustaceans. Nevertheless, Hg toxicity on Procambarus clarkii is largely unknown. In this research, the acute Hg-induced alterations of biochemical responses, histopathology, hepatopancreatic transcriptome, and intestinal microbiome of Procambarus clarkii were studied. Firstly, Hg induced significant changes in reactive oxygen species (ROS) and malonaldehyde (MDA) content as well as antioxidant enzyme activity. Secondly, Hg exposure caused structural damage to the hepatopancreas (e.g., vacuolization of the epithelium and dilatation of the lumen) as well as to the intestines (e.g., dysregulation of lamina epithelialises and extension of lamina proprias). Thirdly, after treatment with three different concentrations of Hg, RNA-seq assays of the hepatopancreas revealed a large number of differentially expressed genes (DEGs) linked to a specific function. Among the DEGs, a lot of redox metabolism- (e.g., ACOX3, SMOX, GPX3, GLO1, and P4HA1), ion transport- (e.g., MICU3, MCTP, PYX, STEAP3, and SLC30A2), drug metabolism- (e.g., HSP70, HSP90A, CYP2L1, and CYP9E2), immune response- (e.g., SMAD4, HDAC1, and DUOX), and apoptosis-related genes (e.g., CTSL, CASP7, and BIRC2) were identified, which suggests that Hg exposure may perturb the redox equilibrium, disrupt the ion homeostasis, weaken immune response and ability, and cause apoptosis. Fourthly, bacterial 16S rRNA gene sequencing showed that Hg exposure decreased bacterial diversity and dysregulated intestinal microbiome composition. At the phylum level, there was a marked decrease in Proteobacteria and an increase in Firmicutes after exposure to high levels of Hg. With regards to genus, abundances of Bacteroides, Dysgonomonas, and Arcobacter were markedly dysregulated after Hg exposures. Our findings elucidate the mechanisms involved in Hg-mediated toxicity in aquatic crustaceans at the tissue, cellular, molecular as well as microbial levels.

Exploration of immune response mechanisms in cadmium and copper co-exposed juvenile golden cuttlefish (Sepia esculenta) based on transcriptome profiling

Sepia esculenta is a popular economic cephalopod with high yield, delicious meat, and rich nutrition. With the rapid development of heavy industry and medical industry, a large amount of waste has been released into the ocean recklessly in recent years, inducing a significant increase in the content of heavy metals, especially cadmium (Cd) and copper (Cu), in the ocean. This phenomenon significantly affects the growth and development of S. esculenta, causing a serious blow to its artificial breeding. In this study, transcriptome analysis is used to initially explore immune response mechanisms of Cd and Cu co-exposed juvenile S. esculenta. The results show that 1,088 differentially expressed genes (DEGs) are identified. And DEGs functional enrichment analysis results suggests that co-exposure may promote inflammatory and innate immune responses in juvenile S. esculenta. Fifteen key genes that might regulate the immunity of S. esculenta are identified using protein-protein interaction (PPI) network and KEGG enrichment analyses, of which the three genes with the highest number of interactions or involve in more KEGG pathways are identified as hub genes that might significantly affect the immune response processes. Comprehensive analysis of PPI network and KEGG signaling pathway is used for the first time to explore co-exposed S. esculenta juvenile immune response processes. Our results preliminarily reveal immune response mechanisms of cephalopods exposed to heavy metals and provide a valuable resource for further understanding of mollusk immunity.

Transcriptomic and Histological Analysis of the Greentail Prawn (Metapenaeus bennettae) Following Light Crude Oil Exposure

Oil spills pose a significant threat to marine biodiversity. Crude oil can partition into sediments where it may be persistent, placing benthic species such as decapods at particular risk of exposure. Transcriptomic and histological tools are often used to investigate the effects of hydrocarbon exposure on marine organisms following oil spill events, allowing for the identification of metabolic pathways impacted by oil exposure. However, there is limited information available for decapod crustaceans, many of which carry significant economic value. In the present study, we assess the sublethal impacts of crude oil exposure in the commercially important Australian greentail prawn (Metapenaeus bennettae) using transcriptomic and histological analyses. Prawns exposed to light, unweathered crude oil "spiked" sediments for 90 h were transferred to clean sediments for a further 72 h to assess recovery. Chemical analyses indicated that polycyclic aromatic hydrocarbons increased by approximately 65% and 91% in prawn muscle following 24 and 90 h of exposure, respectively, and significantly decreased during 24- and 72-h recovery periods. Transcriptomic responses followed an exposure and recovery pattern with innate immunity and nutrient metabolism transcripts significantly lowered in abundance after 24 h of exposure and were higher in abundance after 72 h of recovery. In addition, transcription/translation, cellular responses, and DNA repair pathways were significantly impacted after 24 h of exposure and recovered after 72 h of recovery. However, histological alterations such as tubule atrophy indicated an increase in severity after 24 and 72 h of recovery. The present study provides new insights into the sublethal impacts of crude oil exposure in greentail prawns and identifies molecular pathways altered by exposure. We expect these findings to inform future management associated with oil extraction activity and spills. Environ Toxicol Chem 2022;41:2162-2180. © 2022 John Wiley & Sons Ltd. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Host-pathogen coevolution drives innate immune response to Aphanomyces astaci infection in freshwater crayfish: transcriptomic evidence

BACKGROUND

For over a century, scientists have studied host-pathogen interactions between the crayfish plague disease agent Aphanomyces astaci and freshwater crayfish. It has been hypothesised that North American crayfish hosts are disease-resistant due to the long-lasting coevolution with the pathogen. Similarly, the increasing number of latent infections reported in the historically sensitive European crayfish hosts seems to indicate that similar coevolutionary processes are occurring between European crayfish and A. astaci. Our current understanding of these host-pathogen interactions is largely focused on the innate immunity processes in the crayfish haemolymph and cuticle, but the molecular basis of the observed disease-resistance and susceptibility remain unclear. To understand how coevolution is shaping the host's molecular response to the pathogen, susceptible native European noble crayfish and invasive disease-resistant marbled crayfish were challenged with two A. astaci strains of different origin: a haplogroup A strain (introduced to Europe at least 50 years ago, low virulence) and a haplogroup B strain (signal crayfish in lake Tahoe, USA, high virulence). Here, we compare the gene expression profiles of the hepatopancreas, an integrated organ of crayfish immunity and metabolism.

RESULTS

We characterised several novel innate immune-related gene groups in both crayfish species. Across all challenge groups, we detected 412 differentially expressed genes (DEGs) in the noble crayfish, and 257 DEGs in the marbled crayfish. In the noble crayfish, a clear immune response was detected to the haplogroup B strain, but not to the haplogroup A strain. In contrast, in the marbled crayfish we detected an immune response to the haplogroup A strain, but not to the haplogroup B strain.

CONCLUSIONS

We highlight the hepatopancreas as an important hub for the synthesis of immune molecules in the response to A. astaci. A clear distinction between the innate immune response in the marbled crayfish and the noble crayfish is the capability of the marbled crayfish to mobilise a higher variety of innate immune response effectors. With this study we outline that the type and strength of the host immune response to the pathogen is strongly influenced by the coevolutionary history of the crayfish with specific A. astaci strains.

The effect of a polystyrene nanoplastic on the intestinal microbes and oxidative stress defense of the freshwater crayfish, Procambarus clarkii

The widespread generation and accumulation of plastic waste has become a globally recognized problem. However, there are limited reports on the adverse effects of nanomaterials on freshwater crustaceans. This study tested the acute effects of different concentrations (0, 5, 10, and 20 mg/L) after 48 h exposure of 75 nm polystyrene nanoplastic on intestinal microbes, and oxidative stress parameters of freshwater crayfish, Procambarus clarkii. High-throughput sequencing analysis revealed the richness, diversity, and composition of intestinal microbiota in P. clarkii exposed to polystyrene nanoplastic. At the genus level, abundances of Lactobacillus, Faecalibaculum, Niveibacterium, and Candidatus Bacilloplasma were significantly different. The reduced abundance of Lactobacillus could affect the balance of intestinal microbes through quantitative disadvantage, which may lead to reduced immunity of P. clarkii. Streptococcus salivarius, Clostridium butyricum and Lachnospiraceae bacterium10-1 in intestinal tract reached maximum abundance at a polystyrene concentration of 20 mg/L. The increase in the number of some pathogenic bacteria may upset the balance of intestinal microorganisms through the number of dominance, and the decrease in the relative abundance of lactic acid bacteria. Probiotics, such as Lactobacillus salivarius, Lactobacillus murinus, Lactobacillus gasseri, Lactobacillus reuteri, Lactobacillus iners AB-1, and Lactobacillus crispatus in the intestinal tract reached the lowest value at a concentration of 10 mg/L. The reduced abundance of Lactobacillus can affect the balance of intestinal microbes through quantitative disadvantage, which may lead to reduced immunity in P. clarkii. At nanoplastic 10 mg/L, the relative abundance of intestinal pathogens increased, while the relative abundance of lactic acid bacteria and other probiotics decreased. With increases in nanoplastic concentrations, the values of glutathione (GSH), superoxide dismutase (SOD), acid phosphatase (ACP), lysozyme (LZM), alkaline phosphatase (AKP), peroxidase (POD), glutathione peroxidase (GPX), and protein carbonylation were significantly changed. Our data suggested that Lactobacillus may play an adjunctive role in the treatment of oxidative stress in P. clarkii exposed to 75 nm polystyrene. This study represents an important step towards a better understanding of the toxic effects of nanoplastics on aquatic crustaceans.

Combined toxic effects of thiamethoxam on intestinal flora, transcriptome and physiology of Pacific white shrimp Litopenaeus vannamei

The environmental accumulation of thiamethoxam has increasingly become a risk for the health of aquatic animals, especially crustacean species in the same phylum as the target pests. The lack of knowledge on the toxicity of thiamethoxam to crustaceans motivates our research to study the acute and chronic toxicity of decapod crustaceans Litopenaeus vannamei, exposed to thiamethoxam. A 28-day chronic toxicity test followed a 96 h acute toxicity test. Thiamethoxam induced oxidative stress and decreased growth performance in shrimp. In addition, thiamethoxam has led to a substantial imbalance of the micro-ecosystem in the intestine. The composition of the intestinal flora changed significantly, and the balance of the interaction network in genera was broken. The competitive interaction of many bacteria becomes an unstable cooperative interaction. Transcriptomic analysis showed that the numbers of up- and down-regulated differentially expressed genes (DEGs) increased in a dose-dependent manner. These DEGs were significantly enriched in pathways related to detoxification, and the expression of most detoxification genes was upregulated. DEGs related to detoxification were positively correlated with Shimia and negatively correlated with Pseudoalteromonas. This study provides evidence for the first time on the toxic effects of thiamethoxam on the growth, biochemistry, intestinal flora, and transcriptome in crustaceans.

Behavior and toxicity assessment of copper nanoparticles in aquatic environment: A case study on red swamp crayfish

With the wide use of copper nanoparticles (CuNPs) in various industrial and commercial applications, they inevitably enter the aquatic environment. However, their behavior in the aquatic environment and potential toxicity to aquatic organisms remain little known. In this study, we investigated the behavior of CuNPs in freshwater, as well as the toxicity and bioaccumulation of CuNPs and copper sulfate (CuSO₄), used as a positive control for copper ions toxicity, in red swamp crayfish (Procambarus clarkii). The results showed that CuNPs released copper ions into freshwater and aggregated rapidly in freshwater, and their release of copper ions and aggregation slowed down at a higher concentration of CuNPs. The calculated 72-h LC₅₀ values for crayfish were 1.18 and 0.54 mg/L for CuNPs and CuSO₄, respectively. Cu accumulation in the gill and hepatopancreas from CuSO₄ treatments was significantly higher than that from CuNPs, and the highest Cu bioaccumulation level in crayfish was found in the gill, followed by hepatopancreas and muscle with the exposure of copper. The activities of the antioxidative enzymes in the crayfish significantly decreased after exposure to CuNPs for 48 h, compared to the control (without CuNPs or CuSO₄). Histological examination revealed that there was no significant alteration of hepatopancreas in the crayfish exposed to CuNPs. Meanwhile, the growth of crayfish was not significantly inhibited by CuNPs. These results suggested that CuNPs exposure can induce oxidative stress in the crayfish, gill is the main tissue for their accumulation, and their toxicity is mainly caused by the released copper ions.

Transcriptome Analysis and SNP Identification Reveal That Heterologous Overexpression of Two Uncharacterized Genes Enhances the Tolerance of Magnaporthe oryzae to Manganese Toxicity

Manganese is a crucial trace element that constitutes the cofactors of many enzymes. However, excessive Mn2+ can be toxic for both prokaryotes and eukaryotes. The mechanism of fungal genetics and metabolism in response to Mn2+ stress remains understudied, warranting further studies. Magnaporthe oryzae is well-established as the most destructive pathogen of rice. A field strain, YN2046, more sensitive to Mn2+ toxicity than other strains, was obtained from a previous study. Herein, we explored the genetic mechanisms of Mn2+ sensitivity in YN2046 through comparative transcriptomic analyses. We found that many genes previously reported to participate in Mn2+ stress were not regulated in YN2046. These non-responsive genes might cause Mn2+ sensitivity in YN2046. Weight gene correlation network analysis (WGCNA) was performed to characterize the expression profile in YN2046. Some overexpressed genes were only found in the Mn2+ tolerant isolate YN125. Among these, many single nucleotide polymorphism (SNP) were identified between YN125 and YN2046, which might disrupt the expression levels of Mn responsive genes. We cloned two uncharacterized genes, MGG_13347 and MGG_16609, from YN125 and transformed them to YN2046 with a strong promoter. Our results showed that the heterologous overexpression of two genes in YN2046 restored its sensitivity. Transcriptomic and biochemical analyses were performed to understand Mn tolerance mechanisms mediated by the two heterologous overexpressed genes. Our results showed that heterologous overexpression of these two genes activated downstream gene expression and metabolite production to restore M. oryzae sensitivity to Mn, implying that SNPs in responsive genes account for different phenotypes of the two strains under Mn stress. IMPORTANCE Heavy metals are used for fungicides as they target phytopathogen in multiple ways. Magnaporthe oryzae is the most destructive rice pathogen and is threatening global rice production. In the eukaryotes, the regulation mechanisms of Mn homeostasis often focus on the posttranslation, there were a few results about regulation at transcript level. The comparative transcriptome analysis showed that fewer genes were regulated in the Mn-sensitive strain. WGCNA and SNP analyses found that mutations in promoter and coding sequence regions might disrupt the expression of genes involved in Mn detoxification in the sensitive strain. We transferred two unannotated genes that were cloned from the Mn-tolerant strain into a sensitive strain with strong promoters, and the transformants exhibited an enhanced tolerance to Mn2+ toxicity. Transcriptome and biochemistry results indicated that heterologous overexpression of the two genes enhanced the tolerance to Mn toxicity by reactivation of downstream genes in M. oryzae.

Isolation of the 3β-HSD promoter from Digitalis ferruginea subsp. ferruginea and its functional characterization in Arabidopsis thaliana

BACKGROUND

Although members of the SDR gene family (short chain dehydrogenase) are distributed in kingdom of life, they have diverse roles in stress tolerance mechanism or secondary metabolite biosynthesis. Nevertheless, their precise roles in gene expression or regulation under stress are yet to be understood.

METHODS

As a case study, we isolated, sequenced and functionally characterized the 3β-HSD promoter from Digitalis ferruginea subsp. ferruginea in Arabidopsis thaliana.

RESULTS

The promoter fragment contained light and stress response elements such as Box-4, G-Box, TCT-motif, LAMP element, ABRE, ARE, WUN-motif, MYB, MYC, W box, STRE and Box S. The functional analysis of the 3β-HSD promoter in transgenic Arabidopsis seedlings showed that the promoter was expressed in cotyledon and root elongation zone in 2 days' seedlings. However, this expression was extended to hypocotyl and complete root in 6 days' seedlings. In 20 days-old seedlings, promoter expression was distributed to the whole seedling including hydathodes aperture, vascular bundle, shoot apical meristem, trichomes, midrib, leaf primordia, hypocotyl and xylem tissues. Further, expression of the promoter was enhanced or remained stable under the different abiotic stress conditions like osmotic, heat, cold, cadmium or low pH. In addition, the promoter also showed response to methyl jasmonate (MeJA) application. The expression could not be induced in wounded cotyledon most likely due to lack of interacting elements in the promoter fragment.

CONCLUSIONS

Taken together, the 3β-HSD promoter could be a candidate for the development of transgenic plants especially under changing environmental conditions.

Mechanism of Cadmium Exposure Induced Hepatotoxicity in the Mud Crab (Scylla paramamosain): Activation of Oxidative Stress and Nrf2 Signaling Pathway

Cadmium, one of the most toxic heavy metals, can cause severe oxidative damage to aquatic animals. However, the mechanism whereby the mud crabs respond to cadmium exposure remains unclear. This study investigated the effects of cadmium exposure on oxidative stress and histopathology changes and evaluated the role of the Nrf2 signaling pathway in regulating responses to cadmium-induced hepatotoxicity were investigated in mud crabs. Mud crabs were exposed to 0, 0.01, 0.05, and 0.125 mg/L cadmium for 21 d. The present results indicated that cadmium exposure increased hydrogen peroxide (H₂O₂) production, lipid peroxidation and tissue damage, but decreased the activity of superoxide dismutase (SOD) and catalase (CAT), and caused lipid peroxidation and tissue damage. The results of an integrated biomarker index analysis suggested that the toxicity of cadmium was positively related to cadmium concentration. The expression levels of the Nrf2 signaling pathway (Nrf2, metallothionein, and cytochrome P450 enzymes) were up-regulated after cadmium exposure. Silencing of Nrf2 in vivo decreased antioxidant gene (SOD, CAT, and glutathione S-transferase) expression, suggesting that Nrf2 can regulate antioxidant genes. Knocking down Nrf2 in vivo also significantly decreased the activity of SOD and CAT after cadmium exposure. Moreover, silencing of Nrf2 in vivo enhanced H₂O₂ production and the mortality rates of mud crabs after cadmium exposure. The present study indicated that cadmium exposure induced hepatotoxicity in the mud crab by increasing H₂O₂ content, which decreased the antioxidant capacity, leading to cell injury. In addition, the Nrf2 is activated to bound with antioxidant response element, initiating the expression of antioxidant enzyme genes during cadmium induced hepatotoxicity in the mud crabs.

Moderate acidification mitigates the toxic effects of phenanthrene on the mitten crab Eriocheir sinensis

Freshwater acidification and phenanthrene may result in complex adverse effects on aquatic animals. Juvenile Chinese mitten crabs (Eriocheir sinensis) were exposed to different pH levels (7.8, 6.5, and 5.5) under phenanthrene (PHE) (0 (control) and 50 μg/L) conditions for 14 days. Antioxidant and transcriptomic responses were determined under stress conditions to evaluate the physiological adaptation of crabs. Under the control pH 7.8, PHE led to significantly reduced activities of superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR) and glutathione S-transferase (GST), but increased glutathione peroxidase (GSH-Px), 7-ethoxyresorufin-o-deethylase (EROD) activities, and malondialdehyde (MDA) levels. However, moderate acidification (pH 6.5) changed PHE effects by increasing antioxidant enzymes. Acidification generally reduced SOD, GPx, GST and EROD activities, but increased CAT, GR, MDA. Compared with pH7.8 group, pH7.8 × PHE and pH6.5 × PHE groups had 1148 and 1498 differentially expressed genes, respectively, with "Biological process" being the main category in the two experimental groups. pH7.8 × PHE treatment caused significant enrichment of disease and immune-related pathways, while under pH6.5 × PHE, more pathways related to metabolism, detoxification, environmental information processing, and energy supply were significantly enriched. Thus, PHE had a significant inhibitory effect on antioxidant performance in crabs, while moderate acidification (pH6.5) mitigated the toxic effects of PHE. Overall, moderate acidification has a positive effect on the defense against the negative effects of PHE in Chinese mitten crabs, and this study provides insights into the defense mechanism of crustaceans in response to combined stress of acidification and PHE.

Targeted and untargeted metabolomic analysis of Procambarus clarkii exposed to a "chemical cocktail" of heavy metals and diclofenac

Water pollution poses an important problem, but limited information is available about the joined effects of xenobiotics of different chemical groups to evaluate the real biological response. Procambarus clarkii (P. clarkii) has been demonstrated to be a good bioindicator for assessing the quality of aquatic ecosystems. In this work, we studied the bioaccumulation of cadmium (Cd), arsenic (As) and diclofenac (DCF) in different tissues of P. clarkii during 21 days after the exposure to a "chemical cocktail" of As, Cd and DCF, and until 28 days considering a depuration period. In addition, a combined untargeted and targeted metabolomic analysis was carried out to delve the metabolic impairments caused as well as the metabolization of DCF. Our results indicate that As and Cd were mainly accumulated in the hepatopancreas followed by gills and finally abdominal muscle. As and Cd show a general trend to increase the concentration throughout the exposure experience, while a decrease in the concentration of these elements is observed after 7 days of the depuration process. This is also the case in the abdominal muscle for Cd, but not for As and DCF, which increased the concentration in this tissue in the depuration phase. The hepatopancreas showed the greatest number of metabolic pathways affected. Thus, we observed a crucial bioaccumulation of xenobiotics and impairments of metabolites in different tissues. This is the first study combining the exposure to metals and pharmaceutically active compounds in P. clarkii by untargeted metabolomics including the biotransformation of DCF.

Transcriptome analysis of Neocaridina denticulate sinensis challenged by Vibrio parahemolyticus

As a common aquatic pathogen, Vibrio parahaemolyticus can cause a variety of diseases of shrimp, especially acute hepatopancreatic necrosis disease (AHPND), which leads to great losses to the aquaculture industry around the world. However, the molecular mechanism of V. parahaemolyticus infection is still unclear. Neocaridina denticulate sinensis is a kind of small ornamental shrimp that is popular in aquarium trade, and due to its tenacious vitality, rapid growth, high reproductive capacity, it is very suitable to be developed as an animal model for basic research on decapod crustaceans. Thus, in this paper, transcriptomes of N. denticulate sinensis hepatopancreas with or without V. parahaemolyticus injection were explored. The results showed that a total of 23,624 genes with the N50 of 2705 bp were obtained. Comparative transcriptomic analysis revealed 21,464 differentially expressed genes between the V. parahaemolyticus infected and non-infected group, of which, 11,127 genes were up-regulated and 10,337 genes were down-regulated. Functional enrichment analysis suggested that many DEGs enriched in immune related pathways, including MAPK signaling pathway, Phosphatidylinositol signaling system, Chemokine signaling pathway, Phagosome and Jak-STAT signaling pathway and so on. Eight genes were selected randomly for qRT-PCR to verify the transcriptome sequencing results and the results showed the expression of these genes were consistent with the transcriptome results. Our work provides a unique and important dataset that contributes to the understanding of the molecular mechanisms of the immune response to V. parahaemolyticus infection and may further provide the basis for the prevention and resolution of bacterial diseases.

The Effect of Zinc Concentration on Physiological, Immunological, and Histological Changes in Crayfish (Procambarus clarkii) as Bio-indicator for Environment Quality Criteria

The release of heavy metals to the environment increased dramatically with industrialization and rapid economic development, and they have accumulated in aquatic organisms. The current study aimed toe valuate the physiological, immunological, and histological changes of crayfish (Procambarus clarkii) as bio-indicator for water quality. Crayfishes of the filed study group were collected from a polluted area (Rosetta branch, Egypt), where the highest concentration for heavy metals in water was for zinc (Zn). Besides the field study group, other crayfishes were exposed to different doses of ZnSO₄ (0, 203, and 406 mg L^-g) corresponding to Zn concentration (0, 46.03, and 92.06 mg L^-1) respectively in aquariums for consecutive 4 days. Heavy metal concentrations in field water sample were arranged as follows: Zn > Fe> Pb > Cu and Mn > Ni > Co > Cd. The result revealed that Zn bioaccumulation increases significantly with the increase of water Zn concentration among the tested groups compared to the control group, where the highest bioaccumulation in all studied tissues (hepatopancreas, gills, and muscles) was observed in the field group and Zn high-dose group. Also, there was a significant increase in the levels of hemolymph uric acid, urea, creatinine, glucose, aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase. Their highest concentrations were observed in the Zn high-dose group and the field group, while the levels of total protein, albumin, and cholesterol showed a significant decrease among the tested groups as compared with the control group. Their determined lowest concentrations were in the Zn high-dose group and field group. Among tested groups, total hemocytes and granulated hemocytes decreased significantly while hyaline hemocytes increased as compared with the control group. Histological damages were observed in hepatopancreas, gills, and muscles in the field and Zn groups. The present study showed that exposure to Zn caused physiological and histological changes in Procambarus clarkia. We assumed that Procambarus clarkia could be used as a sensitive bioindicator for monitoring water quality criteria.

Zn contamination stimulate agonistic behavior and oxidative stress of crayfishes (Procambarus clarkii)

BACKGROUND

As a result of the global industrial revolution, contamination of the ecosystem by heavy metals has given rise to one of the most important ecological and organismic problems. The current study aimed to evaluate the effect of Zn contamination on agonistic behavior and oxidative damage of crayfish.

METHODS

Crayfishes of the field study group were collected from a polluted area (Rosetta branch), where the highest concentration for heavy metals in water was zinc (Zn). Besides the field study group, other crayfishes were exposed to different doses of ZnSO₄ (0, 203, and 406 mg L^-1), which corresponding to Zn concentration (0, 46.03, and 92.06 mg L^-1) respectively in aquariums for consecutive four days. Agonistic behavior is quantified by decreasing fast retreat, slowly back away and no response, increasing initial claw use, active claw use, approach with the threat, approach without threat, and unrestrained behavior.

RESULTS

The result revealed that agonistic behavior increases significantly with the increase of water Zn concentration. Malondialdehyde and catalase levels increased, while glutathione concentration reduced with the increase of Zn concentration.

CONCLUSION

Our current study reveals that zinc exposure is capable of inducing an increase in the social status (agonistics behavior) and oxidative stress parameters in Procambarus clarkii. The increase in aggressive behavior may have major population-level consequences given the high mortality experienced by this crayfish.

Cadmium induced oxidative stress, endoplasmic reticulum (ER) stress and apoptosis with compensative responses towards the up-regulation of ribosome, protein processing in the ER, and protein export pathways in the liver of zebrafish

The present study identified that exposure to 5, 10, and 20 µg/L Cd for 48 days reduced growth, increased Cd accumulation and levels of reactive oxygen species (ROS) and lipid peroxidation, and induced ER stress and cellular apoptosis in the liver in a dose-dependent manner. However, the survival rate was not affected by Cd. The increased production of ROS might result from reduced catalase (CAT) and copper/zinc-superoxide dismutase (Cu/Zn-SOD) activities, which might trigger ER stress pathways and subsequently induce apoptotic responses, ultimately leading to growth inhibition. Transcriptomic analyses indicated that the differentially expressed genes (DEGs) involved in metabolic pathways were significantly enriched and dysregulated by Cd, suggesting that metabolic disturbances may contribute to Cd toxicity. However, there were increases in glutathione peroxidase (GPX) activity, protein levels of metallothioneins (MTs) and heat shock protein 70 (HSP70), and mRNA levels of sod1, cat, gpx, mt2, and hsp70. Furthermore, DEGs related to ribosome, protein processing in the ER, and protein export pathways were significantly enriched and up-regulated by Cd. These increases may be compensatory responses following oxidative stress, ER stress, and apoptosis to resist negative effects. Taken together, we demonstrated that environmentally relevant levels of Cd induced adaptive responses with compensatory mechanisms in fish, which may help to maintain fish survival at the cost of growth.