Response of moulting genes and gut microbiome to nano-plastics and copper in juvenile horseshoe crab Tachypleus tridentatus

Effects of titanium dioxide nanoparticle exposure on the gut microbiota of pearl oyster (Pinctada fucata martensii)

With the advancement of nanotechnology and the growing utilization of nanomaterials, titanium dioxide (TiO2) has been released into aquatic environments, posing potential ecotoxicological risks to aquatic organisms. In this study, the toxicological effects of TiO2 nanoparticles were investigated on the intestinal health of pearl oyster (Pinctada fucata martensii). The pearl oysters were subjected to a 14-day exposure to 5-mg/L TiO2 nanoparticle, followed by a 7-day recovery period. Subsequently, the intestinal tissues were analyzed using 16S rDNA high-throughput sequencing. The results from LEfSe analysis revealed that TiO2 nanoparticle increased the susceptibility of pearl oysters to potential pathogenic bacteria infections. Additionally, the TiO2 nanoparticles led to alterations in the abundance of microbial communities in the gut of pearl oysters. Notable changes included a decrease in the relative abundance of Phaeobacter and Nautella, and an increase in the Actinobacteria, which could potentially impact the immune function of pearl oysters. The abundance of Firmicutes and Bacteroidetes, as well as the expression of genes related to energy metabolism (AMPK, PK, SCS-1, SCS-2, SCS-3), were down-regulated, suggesting that TiO2 nanoparticles exposure may affect the digestive and energy metabolic functions of pearl oysters. Furthermore, the short-term recovery of seven days did not fully restore these levels to normal. These findings provide crucial insights and serve as an important reference for understanding the toxic effects of TiO2 nanoparticles on bivalves.

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.

Change in energy-consuming strategy, nucleolar metabolism and physical defense in Macrobrachium rosenbergii after acute and chronic polystyrene nanoparticles exposure

The COVID-19 pandemic has further intensified plastic pollution due to the escalated use of single-use gloves and masks, consequently leading to the widespread presence of microplastics (MPs) and nanoplastics (NPs) in major rivers and lakes worldwide. Macrobrachium rosenbergii has become an important experimental subject due to its ecological role and environmental sensitivity. In this study, we sought to comprehend the ramifications of NPs on the widely-distributed freshwater prawn, M rosenbergii, by conducting a detailed analysis of its responses to NPs after both 96 h and 30 days of exposure. The transcriptome analysis revealed 918 differentially expressed unigenes (DEGs) after 30 days of NPs exposure (356 upregulated, 562 downregulated) and 2376 DEGs after 96 h of NPs exposure (1541 upregulated, 835 downregulated). The results of DEGs expression indicated that acute NPs exposure enhanced carbohydrate transport and metabolism, fostering chitin and extracellular matrix processes. In contrast, chronic NPs exposure induced nucleolar stress in M. rosenbergii, impeding ribosome development and mRNA maturation while showing no significant changes in glucose metabolism. Our findings underscore the M. rosenbergii distinct coping mechanisms during acute and chronic NPs exposure, elucidating its vital adaptive strategies. These results contribute to our understanding of the ecological implications of NPs pollution and its impact on aquatic animals.