Rooney Andrew A, Crain D Andrew, Woodward Allan R, Guillette Louis J
Department of Zoology, University of Florida, 223 Bartram Hall, P.O. Box 118525, Gainesville, FL 32611-8525, USA.
Gen Comp Endocrinol. 2004 Jan 1;135(1):25-34. doi: 10.1016/j.ygcen.2003.08.008.
Seasonal variation in plasma sex steroid concentrations is common in mature vertebrates, and is occasionally seen in juvenile animals. In this study, we examine the seasonal pattern of sex hormone concentration in juvenile American alligators (Alligator mississippiensis) and make a limited comparison of these seasonal patterns on two different lakes in Florida. Male juvenile alligators from a reference lake, Lake Woodruff, displayed temporal patterns in plasma testosterone (T) concentrations that appear to be seasonal. A similar pattern in plasma estradiol-17beta (E(2)) was observed in juvenile females from Lake Woodruff. Males had significantly elevated T concentrations during the spring and late summer, whereas females had elevated E(2) in the spring and late summer and significantly depressed E(2) concentrations during the winter. A limited 4-month survey of animals from contaminated Lake Apopka found a lack of such seasonality. These results suggest that: (1) healthy wild populations of juvenile alligators have a prolonged peripubescent period that is marked by seasonal hormonal cycles, (2) juvenile alligators exposed to environmental contaminants can lack such seasonal cyclicity, and (3) future studies of juvenile alligators should incorporate such seasonality into the experimental design.
血浆性类固醇浓度的季节性变化在成年脊椎动物中很常见，在幼年动物中也偶尔可见。在本研究中，我们研究了幼年美国短吻鳄（密西西比鳄）性激素浓度的季节性模式，并对佛罗里达州两个不同湖泊中的这些季节性模式进行了有限的比较。来自参考湖泊伍德拉夫湖的雄性幼年短吻鳄血浆睾酮（T）浓度呈现出似乎具有季节性的时间模式。在伍德拉夫湖的幼年雌性短吻鳄中也观察到了类似的血浆雌二醇 - 17β（E₂）模式。雄性在春季和夏末T浓度显著升高，而雌性在春季和夏末E₂升高，在冬季E₂浓度显著降低。对受污染的阿波普卡湖动物进行的为期4个月的有限调查发现缺乏这种季节性。这些结果表明：（1）健康的幼年短吻鳄野生种群有一个延长的青春期前期，其特征是季节性激素周期；（2）暴露于环境污染物的幼年短吻鳄可能缺乏这种季节性周期性；（3）未来对幼年短吻鳄的研究应将这种季节性纳入实验设计。
