Nanopolystyrene and phoxim pollution: A threat to hepatopancreas toxicity in Chinese mitten crab (Eriocheir sinensis).

Significant concerns have been raised by the widespread pollutants phoxim (PHO) and nanopolystyrene (NP) in the natural environment. This study evaluated the toxicity effects on the hepatopancreas of Eriocheir sinensis caused by NP and/or PHO at concentrations found in the environment. Subchronic exposure to NP and/or PHO triggered hepatopancreas histological damage within a 21-day exposure period. The NP, PHO, and co-exposure (NPO) groups exhibited fewer blister-like (B) cells, along with the appearance of vacuolation. Furthermore, these exposures induced impairment in the hepatic tubule mucus barrier and mechanical barrier, as evidenced by altered expression of oxidative stress-related genes, mucin-related genes, and TJ-related genes. Additionally, alterations in immunity-related genes and inflammatory cytokine genes expression were observed. The findings showed that hepatopancreas inflammation was caused by both individual and combined exposure to NP and PHO and that the inflammatory response was exacerbated by the co-exposure. The possible pathways of hepatopancreas toxicity were further investigated by transcriptomic analysis. Hepatopancreas inflammation was brought on by subchronic exposure to PHO and co-exposure; this inflammation was exacerbated by co-exposure and was backed by the activation of NF-κB signaling pathway via targeting-related genes. In summary, this research represents the initial documentation, to the best of our understanding of the detrimental effects of exposured to NP and/or PHO at levels found in the environment disrupt the hepatopancreas mucus and mechanical barrier in crustaceans, triggering inflammatory responses. These findings highlight the significance of NP and/or PHO pollution for hepatopancreas health.

Exposure to nanopolystyrene and phoxim at ambient concentrations causes oxidative stress and inflammation in the intestines of the Chinese mitten crab (Eriocheir sinensis).

Nanopolystyrene (NP) and phoxim (PHO) are common environmental pollutants in aquatic systems. We evaluated the toxic effects of exposure to ambient concentrations of NP and/or PHO in the intestines of the Chinese mitten crab (Eriocheir sinensis). Our study showed that histopathological changes were observed in the intestines. Specifically, NP and/or PHO exposure increased intraepithelial lymphocytes. Furthermore, NP and/or PHO exposure induced oxidative stress, as evidenced by a significant decrease in superoxide dismutase activity (SOD), peroxidase activity (POD), and total antioxidant capacity (T-AOC). Pro-inflammatory gene expression and transcriptome analysis demonstrated that NP and/or PHO exposure induced the intestinal inflammatory response. Transcriptome results showed that NP and/or PHO exposure upregulated the NF-κB signaling pathway, which is considered a key pathway in the inflammatory response. Additionally, the expression of pro-inflammatory genes significantly increased after a single exposure to NP or PHO, but it exhibited a significant decrease after the co-exposure. The downregulation of these genes in the co-exposure group likely suggested that the co-exposure mitigated intestinal inflammation response in E. sinensis. Collectively, our findings mainly showed that NP and/or PHO exposure at ambient concentrations induces oxidative stress and inflammatory response in the intestines of E. sinensis.

Toxic effects of nanopolystyrene and cadmium on the intestinal tract of the Chinese mitten crab (Eriocheir sinensis).

Nanopolystyrene (NP) and cadmium (Cd) are ubiquitous contaminants in aquatic systems. The present study aimed to investigate the toxic effects of exposure to ambient concentrations of NP and/or Cd on the intestinal tract of the Chinese mitten crab (Eriocheir sinensis). Exposure to NP and/or Cd induced oxidative stress, as evidenced by a significant increase in lipid peroxide content (LPO), total antioxidant capacity (T-AOC), and peroxidase activity (POD), and significant decreases in superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) activities in E. sinensis. In addition, exposure to NP and/or Cd imbalanced the homeostasis of the intestinal microbiota, as demonstrated by the significantly increased abundance of Spiroplasma. Transcriptomic and metabolomic analyses were performed to investigate the mechanisms underlying intestinal toxicity. Our results showed that ferroptosis, ABC transporters, phosphotransferase system, apoptosis, and leukocyte transendothelial migration were disturbed after exposure to NP and/or Cd. In particular, Cd exposure affected mucin type O-glycan biosynthesis, purine metabolism, and neuroactive ligand-receptor interaction. Intriguingly, co-exposure to NP and Cd might mitigate intestinal toxicity by decreasing oxidative stress and affecting these pathways. Taken together, our study clearly demonstrates that exposure to NP and/or Cd at environmentally relevant concentrations causes intestinal toxicity in E. sinensis.

RNAi silencing of the 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) gene inhibits vitellogenesis in Chinese mitten crab Eriocheir sinensis.

The sesquiterpenoid methyl farnesoate (MF), a de-epoxide form of insect juvenile hormone III (JH III), plays an essential role in regulating many crucial physiological processes in crustaceans including vitellogenesis and reproduction. 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) is an important rate-limiting enzyme in the mevalonate pathway, which is critical for the synthesis of JH III and MF. In the present study, a full-length cDNA encoding HMGR (EsHMGR) in Eriocheir sinensis was isolated and characterised. Sequence analysis of EsHMGR revealed that it belongs to Class I HMGR family proteins with HMG-CoA-binding and NADPH-binding domains, both important for HMGR activity. In addition to its ubiquitous tissue expression, expression of EsHMGR was highly specific to the ovary, the main site of Vg synthesis. During ovarian development, EsHMGR expression in ovary displayed a stage-specific pattern, and was correlated with expression of vitellogenin (EsVg) in hepatopancreas, which suggests that EsHMGR possibly involved in vitellogenesis. To further investigate the functional role of EsHMGR in vitellogenin biosynthesis in E. sinensis, RNA interference-mediated gene silencing was carried out both in vitro and in vivo. Quantitative PCR results showed that injection of EsHMGR double-stranded RNA (dsRNA) led to a significant decrease in EsVg expression levels in ovary and hepatopancreas both in vitro and in vivo. Taken together, the results suggest that EsHMGR is involved in vitellogenin biosynthesis in female E. sinensis, which may provide a new resource for HMGR enzymes participating in reproduction in crustaceans.

Molecular evidence for farnesoic acid O-methyltransferase (FAMeT) involved in the biosynthesis of vitellogenin in the Chinese mitten crab Eriocheir sinensis.

Sesquiterpenoid methyl farnesoate (MF), a crustacean equivalent of insect juvenile hormone (JH III), has essential functions in regulating physiological processes in crustaceans, including reproduction and vitellogenesis. Farnesoic acid O-methyltransferase (FAMeT) is a key rate-limiting enzyme catalyzing the conversion of farnesoic acid (FA) to JH/MF in insects and crustaceans. In this study, a full-length cDNA of EsFAMeT from Eriocheir sinensis was isolated and characterized. The deduced EsFAMeT amino acid sequence indicated there were two conserved Methyltransf-FA domains characteristic of FAMeT family proteins. With use of sequence alignment analysis procedures, there was an indication that FAMeT proteins are highly conserved among crustaceans and FAMeT is more closely related to crustacean FAMeT than to insect FAMeT. Results from quantitative real-time PCR analysis revealed there was ubiquitous EsFAMeT in all tissues examined, with greater abundances of mRNA transcripts in the ovary. The transcription of EsFAMeT indicated there were stage-specific patterns in the hepatopancreas and ovary during ovarian development, with the greatest abundance during ovarian development Stages II and III, respectively. To investigate functions of EsFAMeT in vitellogenin biosynthesis in E. sinensis, RNA interference-mediated gene knockdown was used in vitro and in vivo. Injection of EsFAMeT dsRNA resulted in a marked decrease in EsVg (encoding vitellogenin) transcripts in the ovary and hepatopancreas both in vitro and in vivo. Results from the present study indicated EsFAMeT is involved in vitellogenin biosynthesis in the ovary and hepatopancreas of E. sinensis, providing a new resource to study modulatory effects of the FAMeT family of enzymes in crustacean reproduction.