Exposure to Boscalid Induces Reproductive Toxicity of Zebrafish by Gender-Specific Alterations in Steroidogenesis

Abstract

Boscalid is a succinate dehydrogenase inhibitor fungicide and is frequently detected in surface water. Due to the frequent detection of boscalid, we evaluated its impact on the reproduction of adult zebrafish following a 21 d exposure to 0, 0.01, 0.1, and 1.0 mg/L. Following exposure to boscalid, the fertility of female zebrafish and fertilization rate of spawning eggs were reduced in a concentration-dependent manner up to a respective 87% and 20% in the highest concentration. A significant 16% reduction in the percentage of late vitellogenic oocytes was noted in ovaries, and a significant 74% reduction in the percentage of spermatids in testis was also observed after treatment with 1.0 mg/L. 17β-Estradiol (E2) concentrations decreased significantly in females (34% decrease) but significantly increased in males (15% increase) following 1.0 mg/L boscalid treatment. The expression of genes (such as era, er2b, cyp19a, and cyp19b) related to the hypothalamus-pituitary-gonad-liver (HPGL) axis was significantly altered and positively correlated with E2 concentrations in female and male zebrafish (p < 0.05). Molecular docking results revealed that the binding modes between boscalid and target proteins (ER and CYP19) of zebrafish were similar to that of the reference compounds and the target proteins. The binding energies indicate that boscalid may have a weak estrogen-like binding effect or CYP19 inhibition, potentially altering the HPGL axis, thereby reducing E2 concentrations and fecundity in females. In contrast, boscalid caused significant induction of E2 steroidogenesis and subsequent feminization of gonads in males, indicating gender-specific adverse outcome pathways.

WITHDRAWN: Exposure to Difenoconazole Induces Reproductive Toxicity of Zebrafish by Interfering Reproductive Behavior

“…In Qian et al's study, the same phenomenon was observed in zebra sh after 21 d of exposure to boscalid (0.1 and 1.0 mg/L) (Qian et al, 2020). Not surprisingly, our results also showed that the percentage of LV, SD and SZ were signi cantly decreased in 1.0 or 10 µg/L DCZ treatment groups (Fig.…”

“…After 120 days of DCZ exposure, six serum samples (three female serum samples and three male serum samples) were selected from each treatment group to determine the content of 17β-estradiol (E2), testosterone (T), and vitellogenin (VTG). The levels of E2, T, and VTG are detected by using enzyme-linked immunosorbent assay (ELISA) kits (MSKBIO, Wuhan, China) as previously described (Qian et al, 2020).…”

“…At 120 dpf, the liver, brain, and gonads of the same sex were sampled to analyze the expression levels of genes related to the HPGL axis. All primers of target genes were based on previous studies (Qian et al, 2020;Qiu et al, 2021) and listed in Table S1. The housekeeping gene β-actin was used as an internal control.…”

“…Chen and Chan, 2016;Hansen et al, 1998;Qian et al, 2020). Changes in sex hormones and VTG also further indicated that the development of the gonads is inhibited by DCZ.…”

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

“…A similar change was observed after 21 days of exposure to zebrafish with 1mg/L boscalid. The female fish’s fertility decreased, and the oocyte stage distribution in the ovary was abnormal, but the GSI value did not change (Qian et al, 2020). At the same time, CyB exposure also significantly affected the reproductive system of male zebrafish.…”