Physiological and Molecular Causes of Genetic Variation/Covariation Inendocrine Regulation

虽然关于内分泌学的生理、生化和分子方面的信息很多，但对内分泌调节的进化知之甚少。在适应性进化的初始阶段，基于遗传的内分泌特征变异提供了自然选择所依据的原材料。因此，理解荷尔蒙控制进化的关键一步是表征物种内内分泌调节的基于遗传的变异。这项多学科研究的目的是确定导致蟋蟀种中保幼激素酯酶(JHE)遗传变异的可变分子和生理因素。JHE降解和调节关键的昆虫激素，保幼激素，在过去的15年里一直是首席调查员实验室密集研究的对象。这项提议有三个主要的研究目标。首先，使用体内和体外两种方法，将检验以下假设：神经激素浓度或组织敏感性的遗传变异导致JHE活性和组织分布的遗传变异。实验将在很大程度上评估从JHE活性高或低的遗传库中提取或植入的神经组织对相同和交替品系的JHE活性和相关内分泌特性的影响。其次，将检验JHE信使RNA丰度变异作为JHE活性遗传变异的原因所起的作用。利用来自最近获得的几乎全长的JHE cDNA的探针，利用Northern blotts比较高活性和低活性品系之间的JHE mRNA丰度。第三，将JHE活性高和低的品系进行杂交和回交，以确定(1)JHE活性和相关内分泌性状、(2)这些性状的分子相关性(JHE mRNA水平)和(3)这些性状的潜在调控因子之间的共分离程度。这项研究将同时为生物学的几个不同领域提供重要的新信息。这将是第一次在自然种群中确定内分泌调节基因变异的分子和生理原因的研究。这个项目将导致内分泌生理学、分子生物学和数量遗传学的首次详细合成。最后，这些研究将构成对自然种群神经内分泌调节的遗传变异的第一次调查，并将为随后识别这些调节因子和编码它们的基因奠定基础。

Although a tremendous amount of information is available on physiological, biochemical, and molecular aspects of endocrinology, very little is known about the evolution of endocrine regulation. Genetically-based variations in endocrine traits provide the raw material upon which natural selection acts during the initial stages of adaptive evolution. Thus, a key step in understanding the evolution of hormonal control is the characterization of genetically-based variation in endocrine regulators within species. The goal of the present multi-disciplinary study is to identify the variable molecular and physiological factors that cause genetically-based variation in the enzyme juvenile hormone esterase (JHE) in a cricket species. JHE degrades and regulates the key insect hormone, juvenile hormone, and has been the subject of intensive study in the Principal Investigator's laboratory during the past 15 years. This proposal has three primary research objectives. First, using both in vivo and in vitro approaches, the following hypothesis will be tested: genetic variation in the concentration of or tissue sensitivity to neurohormones causes genetically based variation in JHE activity and tissue distribution. Experiments will largely involve assessing the effect of extracts or implants of neural tissue derived from high- or low- JHE activity genetic stocks on JHE activity and related endocrine traits in the same vs alternate lines. Second, the role of variation in JHE messenger RNA abundance as the cause of genetically-based variation in JHE activity will be tested. JHE mRNA abundance will be compared between high and low activity lines using Northern blots employing a probe derived from a recently obtained, nearly full-length JHE cDNA. Third, the high and low JHE activity lines will be crossed and backcrossed to determine the degree of co-segregation among (1) JHE activity and associated endocrine traits, (2) molecular correlates of these traits (JHE mRNA level), and (3) potential regulators of these traits. This research will simultaneously provide important new information for several different areas of biology. This will be the first study to identify the molecular and physiological causes of genetically-based variation in an endocrine regulator in natural populations. This project will result in the first detailed synthesis of endocrine physiology, molecular biology, and quantitative genetics. Finally, these studies will constitute the first investigations of genetic variation in neuroendocrine regulation in natural populations and will set the stage for subsequent identification of these regulators and the genes that encode them.