Experimental manipulation of steroid concentrations in circulation and in egg yolks of turtles.
Experimental manipulation of steroid concentrations in circulation and in egg yolks of turtles.
复制标题
海龟循环和蛋黄中类固醇浓度的实验操作。
DOI：
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
S. Ford
中科院分区：
文献类型：
--
作者：
F. J. Janzen;M. E. Wilson;J. Tucker;S. Ford
在卵生脊椎动物中，蛋黄中的类固醇激素越来越被认为是母体和后代健康的重要组成部分。然而，除了鸟类之外，人们对雌性分配这些资源的机制知之甚少。我们通过橡胶植入物控制生殖成熟雌性红耳滑龟（Trachemys scripta elegans）的全身激素水平，以验证激素作为循环水平的定量函数分配给发育卵泡的假设。9月初，在实验操作之前，海龟表现出相似的循环类固醇（双氢睾酮、雌二醇-17 β或睾酮）含量（<1 ng/ml）。硅胶植入治疗后，循环类固醇水平明显增加。冬眠后的第二年4月，循环中的双氢睾酮水平已经恢复到植入前的水平，但在雌二醇-17 β和睾酮治疗的海龟中，循环中的雌二醇-17 β和睾酮水平在整个4月都保持显著升高。以睾酮为重点，我们检测到睾酮处理龟的成熟卵泡蛋黄中的睾酮浓度比对照组龟的成熟卵泡蛋黄高近6倍。我们的研究结果支持了一个假设，即海龟蛋黄中的类固醇浓度反映了卵泡发育过程中类固醇的循环浓度，而不是雌性选择性地将特定数量的类固醇激素分别分配给每个鸡蛋。我们的研究结果还强调了一个明确的生理机制，即卵生物种的非遗传母体效应可以直接影响胚胎发育所经历的营养环境。
Steroid hormones in egg yolks are increasingly recognized as an important component of maternal and offspring fitness in oviparous vertebrates. Yet, except for in birds, the mechanism by which females allocate these resources is poorly understood. We manipulated systemic levels of hormones in reproductively mature female red-eared slider turtles (Trachemys scripta elegans) with silastic implants to test the hypothesis that hormones are allocated to developing follicles as a quantitative function of circulating levels in the females. Turtles exhibited similar amounts (<1 ng/ml) of circulating steroids (dihydrotestosterone, estradiol-17 beta, or testosterone) in early September immediately prior to experimental manipulation. After treatment with silastic implants, circulating levels of steroids increased markedly. By the following April after hibernation, circulating levels of dihydrotestosterone had returned to preimplantation levels, but circulating levels of estradiol-17 beta and testosterone in estradiol-17 beta- and testosterone-treated turtles, respectively, remained substantially elevated through April. Focusing on testosterone, we detected nearly six-fold higher concentrations in yolk from mature follicles from testosterone-treated turtles than in yolk from mature follicles from control turtles. Our results provide support for the hypothesis that concentrations of steroids in egg yolks of turtles reflect circulating concentrations of steroids during follicular development rather than the hypothesis that females selectively allocate specific amounts of steroid hormones to each egg separately. Our findings also highlight an unambiguous physiological mechanism by which nongenetic maternal effects in oviparous species can directly influence the nutritional milieu experienced by developing embryos.
DOI：
10.1016/0300-9629(96)00009-6
发表时间：
1996-07-01
影响因子：
2.3
作者：
Schwabl, H
通讯作者：
Schwabl, H
DOI：
10.1073/pnas.90.24.11446
发表时间：
1993-12-15
影响因子：
11.1
作者：
SCHWABL, H
通讯作者：
SCHWABL, H