Evaluation of harmful impact of low concentration cylindrospermopsin through zebrafish behavioral endpoints under...

Cylindrospermopsin (CYN) is a toxic substance produced by cyanobacteria. It has attracted much attention due to its widespread global distribution, bioaccumulation and multi organ toxicity. This study aims to explore the negative effects of environmentally relevant concentrations (0.5-2000 μg/L) of CYN using different life stages of zebrafish. We found that CYN exposure decreased the spontaneous movement of embryos, reduced the swimming distance and average speed of larvae post 6-days exposure, and interfered with the courtship performance of adult fish after 14 days exposure with effective concentration of 100 and 0.5 μg/L respectively. These behavioral changes were companied by slowed embryonic heart rate, decreased body length in hatched larvae and reduced spawning, fertilization rates, abnormal level of sex hormone in adults. Further analysis indicated a high association between inhibited courtship behaviors and reproductive effects induced by CYN. Transcriptomic analysis of zebrafish larvae showed that genes related to heart development, cytoskeletal structure in muscle cells, and energy metabolism were significantly altered after CYN exposure. These transcriptional changes are consistent with the observed phenotypic symptoms. These findings offer a comprehensive understanding of the toxic effects of CYN exposure on zebrafish from a behavioral perspective.