Effects of metals and persistent organic pollutants on the fitness and health of juveniles of the endangered european sturgeon Acipenser sturio Exposed to W1ater and sediments of the garonne and dordogne rivers

Avoidance behaviour and toxicological impact of sunscreens in the teleost Chelon auratus

There is increasing evidence that sunscreen, more specifically the organic ultra-violet filters (O-UVFs), are toxic for aquatic organisms. In the present study, we simulated an environmental sunscreen exposure on the teleost fish, Chelon auratus. The first objective was to assess their spatial avoidance of environmental concentrations of sunscreen products (i.e. a few μg.L-1 of O-UVFs). Our results showed that the fish did not avoid the contaminated area. Therefore, the second objective was to evaluate the toxicological impacts of such pollutants after 35 days exposure to concentrations of a few μg.L-1 of O-UVFs. At the individual level, O-UVFs increased the hepatosomatic index which could suggest pathological alterations of the liver or the initiation of the detoxification processes. At the cellular level, a significant increase of malondialdehyde was measured in the muscle of fish exposed to O-UVFs which suggests a failure of antioxidant defences and/or an excess of reactive oxygen species.

Stress response and tolerance mechanisms of NaHCO3 exposure based on biochemical assays and multi-omics approach in the liver of crucian carp (Carassius auratus)

The development and utilization of saline-alkaline water, an important backup resource, has received widespread attention. However, the underuse of saline-alkaline water, threatened by the single species of saline-alkaline aquaculture, seriously affects the development of the fishery economy. In this work, a 30-day NaHCO₃ stress experimental study combined with analyses of untargeted metabolomics, transcriptome, and biochemical approaches was conducted on crucian carp to provide a better understanding of the saline-alkaline stress response mechanism in freshwater fish. This work revealed the relationships among the biochemical parameters, endogenous differentially expressed metabolites (DEMs), and differentially expressed genes (DEGs) in the crucian carp livers. The biochemical analysis showed that NaHCO₃ exposure changed the levels of several physiological parameters associated with the liver, including antioxidant enzymes (SOD, CAT, GSH-Px), MDA, AKP, and CPS. According to the metabolomics study, 90 DEMs are involved in various metabolic pathways such as ketone synthesis and degradation metabolism, glycerophospholipid metabolism, arachidonic acid metabolism, and linoleic acid metabolism. In addition, transcriptomics data analysis showed that a total of 301 DEGs were screened between the control group and the high NaHCO₃ concentration group, of which 129 up-regulated genes and 172 down-regulated genes. Overall, NaHCO₃ exposure could cause lipid metabolism disorders and induce energy metabolism imbalance in the crucian carp liver. Simultaneously, crucian carp might regulate its saline-alkaline resistance mechanism by enhancing the synthesis of glycerophospholipid metabolism, ketone bodies, and degradation metabolism, at the same time increasing the vitality of antioxidant enzymes (SOD, CAT, GSH-Px) and nonspecific immune enzyme (AKP). Herein, all results will provide new insights into the molecular mechanisms underlying the stress responses and tolerance to saline-alkaline exposure in crucian carp.