Fish personality affects their exposure to microplastics.

Microplastics (MPs) have been found in nearly half of the fish samples collected from the field worldwide. There are feeding behavior differences caused by animal personality among fish individuals. However, how personality affects the exposure of fish to microplastics is unclear. In this study, adult zebrafish were used as a model to study the effects of fish personality (boldness) on MPs exposure. Experiment showed that zebrafish captured MPs actively when MPs were added to the system but spit part of the MPs out after capturing. Bold zebrafish had higher feeding activities, captured MPs more frequently and swallowed more MPs than shy zebrafish. Zebrafish ingested brine shrimp preferentially when both brine shrimp and MPs were provided at the same time, and less MPs were swallowed in co-ingestion situation. Spearman correlation analysis indicated that there is a significantly positive correlation between boldness and feeding MPs frequency. Results of this work demonstrate that zebrafish mistake MPs as food and capture them actively but can discriminate MPs as inedible substances after ingestion and spit part of the MPs out. Bold zebrafish have a higher MP exposure burden than shy zebrafish due to their difference in feeding behaviors. The influence of fish personality needs to be considered for future toxicity studies and risk assessment of fish exposed to MPs.

Comparative transcriptomic analysis reveals an association of gibel carp fatty liver with ferroptosis pathway.

BACKGROUND: Fatty liver has become a main problem that causes huge economic losses in many aquaculture modes. It is a common physiological or pathological phenomenon in aquaculture, but the causes and occurring mechanism are remaining enigmatic. METHODS: Each three liver samples from the control group of allogynogenetic gibel carp with normal liver and the overfeeding group with fatty liver were collected randomly for the detailed comparison of histological structure, lipid accumulation, transcriptomic profile, latent pathway identification analysis (LPIA), marker gene expression, and hepatocyte mitochondria analyses. RESULTS: Compared to normal liver, larger hepatocytes and more lipid accumulation were observed in fatty liver. Transcriptomic analysis between fatty liver and normal liver showed a totally different transcriptional trajectory. GO terms and KEGG pathways analyses revealed several enriched pathways in fatty liver, such as lipid biosynthesis, degradation accumulation, peroxidation, or metabolism and redox balance activities. LPIA identified an activated ferroptosis pathway in the fatty liver. qPCR analysis confirmed that gpx4, a negative regulator of ferroptosis, was significantly downregulated while the other three positively regulated marker genes, such as acsl4, tfr1 and gcl, were upregulated in fatty liver. Moreover, the hepatocytes of fatty liver had more condensed mitochondria and some of their outer membranes were almost ruptured. CONCLUSIONS: We reveal an association between ferroptosis and fish fatty liver for the first time, suggesting that ferroptosis might be activated in liver fatty. Therefore, the current study provides a clue for future studies on fish fatty liver problems.