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首页> 外文学位 >The role of TGFbeta signaling in ovarian development and follicle assembly in the American alligator.
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The role of TGFbeta signaling in ovarian development and follicle assembly in the American alligator.

机译：在美国短吻鳄中，TGFbeta信号传导在卵巢发育和卵泡组装中的作用。

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摘要

Formation of ovarian follicles, germ cells surrounded by a cohort of supporting somatic cells, is critical of later female reproductive health. As a follicle matures, it fosters the production of a viable egg that, after ovulation, is available for fertilization. Follicles can form improperly. When two or more germ cells become enclosed a single follicle this malformation is a multioocytic follicle (MOF). In laboratory experiments, estrogenic treatments of female rodents before follicle assembly increase MOF frequencies. Further, this estrogenic treatment appears to interfere with appropriate activin signaling. Interactions between estrogen and activin signaling modulate follicle assembly processes. Yearling alligators from Lake Apopka, a site extensively contaminated with endocrine disrupting compounds, show elevated MOF frequencies. Here, we investigate ovarian follicle assembly dynamics and activin signaling in hatchling alligators to understand possible causation and characterize mechanism underlying these malformations of alligator ovaries.;Results demonstrated that alligator follicle assembly occurs over many months following hatching. Complete follicles were not observed under laboratory conditions until three months after hatching. This prolonged developmental process putatively results in a larger window of time in which follicle assembly could be disrupted. Gonadal expression levels of some activin signaling factor mRNA are sexually dimorphic. In 13-month old contaminant exposed alligators, we observed diminished or lost sexual dimorphisms in both male and female alligator gonads. Additionally, these sexually dimorphic expressions of these factors are also present in hatchling animal gonads, both before and during the period of follicle assembly in females. Further, contaminant exposure altered mRNA expression levels of some of these factors. In some gene expressions, mRNA expression levels differences between contaminant exposed and reference site animals became more pronounced when ovaries were gonadotrophin challenged. Ovaries in contaminant-exposed animals showed both greater and lesser expression levels of factors vital for female reproductive health when compared to ovaries from reference site alligators. Therefore, these reproductive differences could affect later hypothalamus-pituitary-gonadal signaling dynamics after puberty. Taken together, these studies demonstrate that exposure to contaminants found in Lake Apopka, even before hatching, can have lasting effects on gonadal endocrine activity and may comprise the causation of Lake Apopka alligator ovarian MOFs.
机译：卵巢卵泡的形成，被支持体细胞群包围的生殖细胞，对以后的女性生殖健康至关重要。随着卵泡的成熟，它促进了卵子的产生，该卵子排卵后可用于受精。卵泡可能形成不正常。当两个或多个生殖细胞被单个卵泡包裹时，这种畸形就是多卵泡卵泡（MOF）。在实验室实验中，在卵泡组装之前对雌性啮齿动物进行雌激素治疗会增加MOF频率。此外，这种雌激素治疗似乎会干扰适当的激活素信号传导。雌激素和激活素信号传导之间的相互作用调节卵泡组装过程。来自阿波普卡湖（Lake Apopka）的一岁短吻鳄，其内分泌干扰化合物受到严重污染，显示出MOF频率升高。在这里，我们调查了孵化的扬子鳄的卵巢卵泡组装动力学和激活素信号传导，以了解可能的原因并描述了这些扬子鳄卵巢畸形的潜在机制。结果表明，孵化后的几个月中扬子鳄卵泡组装发生。直到孵化后三个月，才在实验室条件下观察到完整的卵泡。这种延长的发育过程可能导致更长的时间窗口，在这个时间窗口中卵泡组装可能会受到干扰。某些激活素信号转导因子mRNA的性腺表达水平具有性别双态性。在暴露于污染物的13个月大的短吻鳄中，我们观察到雌雄短吻鳄性腺的性二态性减少或消失。另外，在女性的卵泡组装之前和期间，这些因子的这些性二态表达也存在于孵化的动物性腺中。此外，污染物暴露改变了其中一些因素的mRNA表达水平。在某些基因表达中，当卵巢受到促性腺激素激发时，暴露于污染物的动物和参照位点动物之间的mRNA表达水平差异变得更加明显。与参考地点短吻鳄的卵巢相比，接触污染物的动物的卵巢显示出对女性生殖健康至关重要的因子的表达水平越来越高。因此，这些生殖差异可能会影响青春期后的下丘脑-垂体-性腺信号转导动态。综合起来，这些研究表明，即使在孵化之前，也要暴露于阿波普卡湖中发现的污染物中，这可能会对性腺内分泌活性产生持久影响，并且可能是造成阿波普卡湖鳄鱼卵巢MOF的原因。

著录项

  • 作者

    Moore, Brandon Christopher.;

  • 作者单位

    University of Florida.;

  • 授予单位 University of Florida.;
  • 学科 Biology Anatomy.;Biology Zoology.;Biology Animal Physiology.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 181 p.
  • 总页数 181
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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