Life cycle exposure to cyhalofop-butyl induced reproductive toxicity toward zebrafish

Abstract

Cyhalofop-butyl (CyB) is an herbicide widely used in paddy fields, which may transfer to aquatic ecosystems and cause harm to aquatic organisms. In this study, zebrafish (Danio rerio) were exposed to CyB (0.1, 1 and 10 ug/L) related to the environment throughout its adult life cycle from embryo to sexual maturity. The effects of CyB on zebrafish growth, reproduction and offspring development were studied. It was found that female spawning was inhibited and adult male fertility decreased. In addition, we detected the expression of sex steroid hormones and genes related to hypothalamus-pituitary-gonad-liver (HPGL) axis. After 150days of exposure, the hormone balance of parent zebrafish (F0) was disturbed and the concentrations of 17{beta}-estradiol (E2) and vitellogenin (VTG) in zebrafish were decreased. F1 embryos showed abnormal developmental results, including decreased heart rate, decreased body length, spontaneous motor inhibition, while the developmental abnormalities of F1 embryos were relieved when exposed to CyB-free clear water. The change of sex hormone is regulated by gene expression related to HPGL axis. These results confirmed that long-term exposure to CyB in the environmental concentrations can damage the reproductive capacity of F0 generation zebrafish by disrupting the transcription of genes related to HPGL axis, which may lead to abnormal development of F1. Overall, these data may provide a new understanding of the reproductive toxicity of zebrafish parents and offspring after long-term exposure to CyB. HighlightsO_LIEnvironmental level of CyB exposure caused gonadal impairment. C_LIO_LICyB exposure suppressed spawning ability of zebrafish. C_LIO_LICyB exposure changed the plasma hormone level of zebrafish and altered HPGL axis in both genders. C_LIO_LIParental CyB exposure led to abnormal development of F1. C_LI