Inhibition of final maturation of Atlantic croaker oocytes in vitro by organochlorines
- Univ. of Texas, Port Aransas, TX (United States). Austin Marine Science Inst.
Final oocyte maturation (FOM) in teleosts is induced by a maturation inducing steroid (MIS) secreted in response to a surge in maturational gonadotropin secretion. Recently the authors found that a variety of organochlorine pesticides bind to the ovarian plasma membrane receptor for the MIS in the spotted seatrout (Cynoscion nebulosus). In the present study the interaction of various xenobiotics (10{sup {minus}9}--10{sup {minus}4}M) with MIS-induced final maturation of follicle-enclosed oocytes of Atlantic croaker (Micropogonias undulatus), a closely related species, was investigated using an in vitro oocyte maturation bioassay. A wide range of organochlorine compounds (10{sup {minus}9}--10{sup {minus}4}M) inhibited MIS-induced FOM 10%-80% in a concentration-dependent manner. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) was the most potent inhibitor among the compounds tested. The minimum concentration of TCDD which inhibited final maturation of 50% of the oocytes (EC{sub 50}) was in the 10{sup {minus}7} M range whereas the EC{sub 50} values for Kepone and naphthalene were in the 10{sup {minus}5}M range. The relative potencies of DDT analogs varied greatly, with EC{sub 50} values ranging from 10{sup {minus}7}--10{sup {minus}4}M (o,p{prime}-DDD > o,p{prime}-DDE > o,p{prime}DDT > p,p{prime}-DDE > p,p{prime}-DDE > p,p{prime}-DDT). PCBs only inhibited FOM at higher concentrations (2--200 ppm); congeners with higher chlorine contents were the most inhibitory. These results indicate that organochlorine compounds at environmentally realistic concentrations can affect reproduction in fish by interfering with FOM, a critical stage of the reproductive cycle.
- OSTI ID:
- 40095
- Report Number(s):
- CONF-9410273--
- Country of Publication:
- United States
- Language:
- English
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