Milnes Matthew R, Allen Davina, Bryan Teresa A, Sedacca Cassidy D, Guillette Louis J
Department of Zoology, University of Florida, 223 Bartram Hall, Gainesville, FL 32611-8525, USA.
Comp Biochem Physiol C Toxicol Pharmacol. 2004 May;138(1):81-7. doi: 10.1016/j.cca.2004.05.006.
A variety of organochlorine pesticides have been shown to adversely affect embryonic development. A number of abnormalities have been documented in alligators (Alligator mississippiensis) from highly-contaminated Lake Apopka, FL, USA that are similar to the results of experimental studies exposing embryos to pesticides. In the current study, we exposed developing alligator embryos to varying concentrations of toxaphene, a broad-spectrum pesticide found in relatively high concentration in Lake Apopka alligator egg yolk. The toxaphene, dissolved in 50 microl of ethanol, was applied topically to the eggshell just prior to the sex-determining period of development. Shortly after hatching, we examined a number of morphological and physiological endpoints to determine the consequences of sub-lethal embryonic exposure to toxaphene. Our results indicate that toxaphene had little or no effect on the morphological endpoints examined including body mass (BM) and size, liver, thyroid, and gonad development. In addition, toxaphene failed to affect sexual differentiation, or in vitro thyroxin, testosterone (T), and estradiol production. However, male plasma T concentration was higher in animals treated with 10 and 0.01 microg toxaphene/kg (based on mean egg mass) than control males. Because in vitro T production was not different among control groups, we suggest the difference in plasma T could be due to differences in hypothalamic-pituitary stimulation of the gonad or hepatic steroid degradation. This study indicates that technical grade toxaphene, at the applied doses, does not induce the same developmental abnormalities associated with alligators living in Lake Apopka. Future studies should consider the effects of embryonic exposure to a mixture of chemicals, including toxaphene metabolites, on development in alligators to better evaluate the consequences of environmental contamination.
多种有机氯农药已被证明会对胚胎发育产生不利影响。在美国佛罗里达州受高度污染的阿波普卡湖中的密西西比鳄身上记录到了许多异常情况，这些异常与将胚胎暴露于农药的实验研究结果相似。在当前研究中，我们将发育中的密西西比鳄胚胎暴露于不同浓度的毒杀芬中，毒杀芬是一种广谱农药，在阿波普卡湖鳄鱼卵黄中浓度相对较高。将溶解于50微升乙醇中的毒杀芬在发育的性别决定期之前局部涂抹于蛋壳上。孵化后不久，我们检查了一些形态和生理指标，以确定亚致死性胚胎暴露于毒杀芬的后果。我们的结果表明，毒杀芬对所检查的形态指标几乎没有影响，包括体重（BM）和大小、肝脏、甲状腺和性腺发育。此外，毒杀芬未能影响性别分化，或体外甲状腺素、睾酮（T）和雌二醇的产生。然而，用10微克和0.01微克毒杀芬/千克（基于平均卵质量）处理的动物中，雄性血浆T浓度高于对照雄性。由于对照组之间体外T产生没有差异，我们认为血浆T的差异可能是由于下丘脑 - 垂体对性腺刺激或肝脏类固醇降解的差异。这项研究表明，在所应用的剂量下，工业级毒杀芬不会诱发与生活在阿波普卡湖中的鳄鱼相关的相同发育异常。未来的研究应考虑胚胎暴露于包括毒杀芬代谢物在内的化学混合物对鳄鱼发育的影响，以更好地评估环境污染的后果。
