EAGER: Physiological Canalization and Individual Variation

人们早上醒来吃早饭，中午左右吃午餐，晚上吃晚餐。如果天气太热或太冷，就打开空调或炉子。当人们生病或遭受撕裂时，他们会寻求抗生素治疗(如果合适)或卧床休息。然而，在自然环境中，对于野生远交种群的生物来说，生命有更多意想不到的环境变化。对于异纹藻鱼类(这项拟议研究的重点)来说，环境既不可预测，又极其多变。在它们的自然栖息地，Fundulus生活在一个不断变化的环境中，因为它们在北美沿海的上游河口觅食。在退潮时，它们要么在较深的潮汐小溪中，经历较低的海洋温度(10-25摄氏度)，要么，特别是在春季和夏季，它们可能暂时滞留在温暖的潮汐池(25-35摄氏度)的上河口。当它们随着潮汐上升进入沼泽时，它们的盐度每天都会发生变化，从最大强度的海水(33ppt)到不到3ppt(如果下大雨)。这项应用重点研究环境变化如何影响mRNA表达的表型差异。在这一应用中提出的假设是，大多数自然种群存在的可变生态环境隐藏了许多变异。与直觉相反的假设是，对于基因的一个子集，对不同环境的生理反应限制了mRNA表达的个体间差异，这样做掩盖了功能性遗传变异或多态。如果是正确的，那么基因表达的生理性通道隐藏了遗传变异。因此，这项研究提供了一个新的视角，解释了如此多的隐藏基因变异是如何产生的，以及为什么它在自然种群中持续存在。先前没有旨在了解环境如何影响mRNA表达差异的分析，此类研究的一个主要障碍是估计差异需要具有大样本量的特定实验设计。这项应用克服了设计上的挑战，并将产生独特的统计分析，说明基因表达的差异是环境的函数，进而影响进化过程。这项拟议研究的根本重要性在于，它探索了许多遗传变异可能被隐藏的机制，并解决了如何在自然物种种群中保持大量遗传变异的问题。这些发现有可能显著改变在标准的、受控良好的实验室条件下进行的实验结果的观点，从而影响生理、进化和人类健康研究。这项研究在三个领域产生了更广泛的影响。首先，对科学界的贡献包括关于基因表达、cdna序列和近端启动子的大型数据集，这些数据集可以用于其他关于新陈代谢、生理驯化和基因表达调控的研究。这些数据将公之于众。其次，研究生将接受不同生物学领域的培训，包括基因组学、生态学和生理学，以及统计分析。最后，本科生将通过与迈阿密大学的项目互动来吸引他们，这些项目从代表性不足的群体中招收学生，并让他们参与实际操作的科学研究。

In the morning people wake up and have breakfast, they eat lunch around noon, and in the evening they eat dinner. If it is too hot, or too cold, one turns on the air conditioner or the furnace. When people are sick or suffering from a laceration, they seek treatment with antibiotics (if appropriate) or rest in bed. However, in the natural environment for wild outbred populations of organisms, life has many more unexpected environmental variations. For the fish Fundulus heteroclitus (the focus of this proposed study), the environment is both unpredictable and extremely variable. In their natural habitat Fundulus live in a constantly changing environment because they feed in the upper estuaries of coastal North America. At low tides they are either in deeper tidal creeks experiencing lower ocean temperatures (10-25°C) or, especially in spring and summer, can become temporarily lodged in the upper estuaries in warm tidal pools (25-35°C). They experience daily variation in salinity as they move with the tide up into marshes, from full strength seawater (33 parts per thousand, ppt) to less than 3 ppt if it is raining heavily. This application focuses on how environmental variation affects phenotypic variation in mRNA expression. The hypothesis proposed in this application is that much variation is hidden by the variable ecological settings where most natural populations exist. The counter-intuitive hypothesis is that for a subset of genes, the physiological responses to variable environments constrain inter-individual variation in mRNA expression, and in so doing mask functional genetic variation or polymorphisms. If correct, then physiological canalization of gene expression hides genetic variation. Thus, this research provides a novel perspective on how so much hidden genetic variation arises and why it persists in natural populations. There are no prior analyses aimed at understanding how the environment affects the variance in mRNA expression, and a major impediment to such studies is that estimating variance requires specific experimental designs with large sample sizes. This application overcomes the design challenges, and will yield unique statistical analyses of how the variance in gene expression is a function of the environment, and in turn affects evolutionary processes. The fundamental importance of this proposed research is that it explores mechanisms whereby much genetic variation may be hidden, and addresses how large amounts of genetic variation can be maintained in natural species populations. The findings have the potential to significantly alter views of the results of experiments conducted under standard, well-controlled laboratory conditions, and thus influence physiological, evolutionary and human health research.This research has broader impacts in three areas. First, contributions to the scientific community include a large dataset on gene expression, cDNA sequences, and proximal promoters that can be used in other studies on metabolism, physiological acclimation and the regulation of gene expression. These data will be made available publically. Second, a graduate student will be trained in a diversity of biological fields, including genomics, ecology and physiology, and in statistical analyses. Finally, undergraduate students will be attracted to this project through interactions with programs at the University of Miami that recruit students from underrepresented groups and engage them in hands-on scientific research.