Expression of zona pellucida 3 gene is regulated by 17α-ethinylestradiol in adult topmouth culter Culter alburnus.

Estrogen could lead to abnormal modulation or disruption of physical development, reproduction and sexual behavior in aquatic wildlife, especially in fish. Information on the toxicity of estrogens to native species in that can be used in site-specific risk assessments is scarce. In the present study, one zona pellucida 3 (ZP3) homologue termed CaZP3 was firstly identified from topmouth culter Culter alburnus, following its structural characteristics, tissue distribution and transcriptional modulation to 17α-ethinylestradiol (EE2) exposure were investigated. Meanwhile, vitellogenin (VTG) gene was employed to provide a comparison of the reactive ability to EE2 induction. The CaZP3 characterized with analogical functional domains such as ZP domain, SP, IHP, EHP, 12 cysteine residues, one N-linked glycosylation site and two conserved O-linked glycosylation sites and equal number of eight exons and seven introns with ZP3 counterparts of higher species. CaZP3 mRNA predominantly expressed in ovary, besides, highly expressed in female heart and male muscle and relatively high expressed in testis. CaZP3 has the lower reactive ability to EE2 induction in comparison with VTG, however, CaZP3 transcripts were significantly induced in gonads of both male and female culter by EE2 and could be used as an alternative biomarker to monitor EE2 activity. The present results supplement the database for toxicity of EE2, especially for fish species endemic to China and provide some useful information for the monitoring of EE2 activity in aquatic environment.