Effects of nanoplastic exposure on the growth performance and molecular characterization of growth-associated genes in juvenile Macrobrachium nipponense

Effects of nanopolystyrene and/or phoxim exposure on digestive function of Eriocheir sinensis

Nanopolystyrene (NP) and phoxim (PHO) are pervasive environmental contaminants that pose a significant threat to the health of aquatic organisms, prompting widespread concern among researchers and the public alike. The hepatopancreas play important roles in the Chinese mitten crab (Eriocheir sinensis), such as digestion, absorption and detoxification. This study assessed the hepatopancreatic toxicity caused by the exposure of Eriocheir sinensis to environmentally relevant concentrations of NP and/or PHO. After a 21-day exposure period, NP (1.0 × 1010 particles/L) and PHO (24 μg/L) exposure resulted in reduced number of blister-like, resorptive, and fibrillar cells and an elevation in lipid droplets within the hepatopancreas compared to the control group. Furthermore, trypsin and lipase activity decreased, amylase activity increased, and a significantly decrease in the expression of digestion-related genes, including CHT, CarL, and CarB, suggested impairment in both digestive and metabolic functions. The marked upregulation of key genes, including PPARγ, GYK, PEPCK, and SCD, as well as key metabolites such as 4-methylzymosterol-carboxylate, zymosterone, lathosterol, 7-dehydro-desmosterol, vitamin D2, 24-methylene-cycloartanol, 5-dehydroepisterol, and sitosterol in the lipid metabolic pathway, showed that the peroxisome proliferator-activated receptor (PPAR) and steroid biosynthesis signaling pathways were highly affected by exposure to NP and/or PHO. These findings indicated that exposure to NP and/or PHO might adversely affect the hepatopancreatic physiological homeostasis in E. sinensis by causing tissue damage and interfering with digestive and metabolic functions. Our results provide ecotoxicological insights into the effects of nanopolystyrene and/or phoxim exposure on the digestive function of Eriocheir sinensis.

Physiological and molecular effects of contaminants of emerging concerns of micro and nano-size in aquatic metazoans: overview and current gaps in Antarctic species

Although Antarctica is the most isolated continent on Earth, its remote location does not protect it from the impacts of human activities. Antarctic metazoans such as filter-feeding invertebrates are a crucial component of the Antarctic benthos. They play a key role in the benthic-pelagic carbon flux in coastal areas by filtering particles and planktonic organisms from the sediment-water interface. Due to their peculiar ecological niche, these organisms can be considered a wasp-waist in the ecosystem, making them highly sensitive to marine pollution. Recently, anthropogenic particles such as micro-nanoplastics and manufactured nanoparticles (MNP) have been classified as contaminants of emerging concern (CEC) due to their small size range, which also overlaps with the preferred particle size ingested by aquatic metazoans. Indeed, it has been demonstrated that some species such as Antarctic krill can ingest, transform, and release MNPs, making them newly bioavailable for other Antarctic filter-feeding organisms. Similarly, the production and use of anthropogenic MNP are rapidly increasing, leading to a growing presence of materials, such as nano-sized metal-oxides, in the environment. For these reasons, it is important to provide evidence of the adverse effects of such emerging contaminants at sub-lethal concentrations in environmental risk assessments. These contaminants may cause cascade effects with consequences not only on individuals but also at the community and ecosystem levels. In this review, we discuss the state-of-the-art knowledge on the physiological and molecular effects of anthropogenic MNP in Antarctic aquatic metazoans. We further highlight the importance of identifying early biomarkers using sessile metazoans as sentinels of environmental health.

Polystyrene nanoplastics exposure alters muscle amino acid composition and nutritional quality of Pacific whiteleg shrimp (Litopenaeus vannamei)

Litopenaeus vannamei were exposed to 80-nm polystyrene nanoplastics (NPs) at different concentrations (0, 0.1, 1, 5, and 10 mg/L) for 28 days to study the effects on muscle nutritional quality. Our results showed that with increasing NPs concentrations, the survival rate, specific gain rate, and protein efficiency ratio decreased but the feed conversion ratio increased. There was no significant difference in moisture, ash, and crude lipid content in the muscle, and a general decrease in crude protein content was observed. However, the total amino acid and semi-essential amino acid contents decreased. The spacing between muscle fibers and the melting morphology of muscle increased. The hardness of muscle flesh texture increased, but springiness, cohesiveness, and chewiness decreased. Regarding antioxidant enzyme activity, the activity of catalase decreased, but the total antioxidant capacity, superoxide dismutase activity, and reduced glutathione first increased and then decreased. The expression level of the growth-related genes retinoid X receptor (RXR), chitin synthase (CHS), and calmodulin A (CaM) first increased then decreased, but calcium/calmodulin-dependent protein kinase I (CaMKI), ecdysteroid receptor (EcR), chitinase 5 (CHT5), cell division cycle 2 (Cdc2), and cyclin-dependent kinase 2 (CDK2) decreased. Our results suggest that exposure to NPs can inhibit growth by inducing oxidative stress, which leads to muscle tissue damage and changes in amino acid composition. These results will provide a theoretical reference for the risk assessment of NPs and the ecological health aquaculture of shrimp.

Polystyrene nanoplastics induce lipid metabolism disorder and alter fatty acid composition in the hepatopancreas of Pacific whiteleg shrimp (Litopenaeus vannamei)

The impact of nanoplastics (NPs) on environmental pollution and aquatic organisms has gradually attracted attention, but there are relatively few reports of the effects of NPs on the lipid metabolism of crustaceans. In this study, we exposed Pacific whiteleg shrimp (Litopenaeus vannamei) to different concentrations of polystyrene NPs (0, 0.1, 1, 5, and 10 mg/L) for 28 days. We then evaluated the effects of NP exposure on metabolite content, histology, lipid metabolism-related enzyme activity, and gene expression. Our results showed that with increasing NPs concentrations and exposure time, (1) the crude protein and crude fat content decreased and fatty acid composition changed; (2) the tissue structure was destroyed and the number of lipid droplets increased in the hepatopancreas; (3) the activities of acetyl-CoA carboxylase, fatty acid synthase, carnitine palmitoyl transferase-1, pyruvate kinase and low-density lipoprotein content tended to decrease and that of lipase and high-density lipoprotein content first increased and then decreased; the content of triglycerides and total carbohydrate first decreased and then increased; (4) the expression of fatty acid synthesis-related genes (Fas, SREBP, and FAD), fatty acid transport-related genes (FATP, FABP, and ACBP), and fatty acid decomposition-related genes (Ampk and lip1) first increased and then decreased. These results indicate that exposure to NPs can cause physiological disorders of fat metabolism in L.vannamei and that high concentrations of NPs have a negative impact on lipid metabolism. These results of this study provide valuable ecotoxicological data for better interpretation of the mechanism of action of NPs in crustaceans.

Chronic effects of nano and microplastics on reproduction and development of marine copepod Tigriopus japonicus

This study aimed to examine the impact of chronic (30 days) exposure to polystyrene microplastics (PS-MPs) of different sizes (50 nm and 2 µm) and at different concentrations (0.5 μg/L and 100 mg/L) to marine copepod Tigriopus japonicus. Polystyrene microplastics affected survival rates in size- and concentration-dependent manners. The LC₅₀s values of 50 nm and 2 µm PS-MPs were 0.10 mg/L and 3.92 mg/L, respectively. The developmental time was delayed by 50 nm PS-MPs, and Usp expression was downregulated. Reproduction was negatively affected by 2 µm PS-MPs even at environmentally relevant concentrations; however, the expression of Vtg was not altered. The production rates of reactive oxygen species and nitric oxide also increased after exposure to PS-MPs; but this effect was independent of particle size. The expression levels of Cat and Tnf, genes related to oxidative stress and inflammation, respectively, were upregulated by exposure to PS-MPs, independently of particle size. Meanwhile, the level of oxidative stress in T. japonicus was not significantly affected by PS-MPs at environmentally relevant concentrations. This study suggests that nano-sized PS-MPs are not always more toxic than micro-sized PS-MPs, and that oxidative stress is a key factor in determining the toxic effect on T. japonicus at high concentrations.