Fish Skin Mucus Vitellogenin as a Noninvasive, Sensitive Biomarker for Aquatic Xenoestrogens

Environmental estrogens (EEs) can induce vitellogenin (VTG) in fish skin mucosa. However, the applicability of mucus VTG in aquatic xenoestrogen monitoring warrants comprehensive exploration. Here, we employed different estrogen exposure scenarios to compare the applicability of mucus VTG and other conventional biomarkers in zebrafish for EE monitoring. After acute exposure to 17α-ethynylestradiol (EE2) at various concentrations, mucus VTG demonstrated higher sensitivity in male zebrafish than in female zebrafish. Mucus VTG change patterns were similar to liver and blood VTG change patterns in males. Time-course exposure experiments revealed that male mucus VTG responded to EE2 much earlier than male liver and blood VTG, underlining the promise of mucus VTG as an early warning signal of aquatic estrogenicity. Exposure to multiple EEs further validated the high sensitivity of male mucus VTG. Proteomics analysis revealed that EE2 exposure potently shifted the proteome structure of male mucosa, and the VTG1 isoform was noted to be the most suitable biomarker. Overall, our results refine the roles of mucus VTG1 from male fish as a noninvasive, rapid, and sensitive biomarker of aquatic xenoestrogens, applicable to ecological risk assessment for animal welfare and ecosystem protection. Future ecological studies may only need to sample male fish mucus without sacrificing females.