DISSERTATION RESEARCH: Evolutionary Physiology of Heat-Shock Gene Expression

论文研究方向：热休克基因表达的进化生理学拟议的研究将调查一个引人注目的案例，其中转座因子（te，在基因组中具有从一个地方移动到另一个地方的能力的DNA片段）反复但独立地破坏了一个基因的启动子（控制转录的区域），该基因编码可诱导分子伴侣（一种防止或减轻对其他蛋白质损害的蛋白质）；例如，Hsp70]，这反过来又会影响对环境应激的耐受性和适应性。这个系统很有希望作为一个模型来研究生理性状的大规模差异是如何从种群内个体之间的微小变异中产生的。先前的研究已经发现了3个独立的例子，其中在果蝇的自然种群中，TE插入破坏了hsp70Ba近端启动子中热休克反应元件之间的间隔；每个这样的群体都表现出不同的Hsp70蛋白水平。对于每个种群，拟议的研究将开发复制系，用于：(1)量化Hsp70蛋白水平，以测试te中断启动子的果蝇是否表达较少的Hsp70；(2)确定te驱动的Hsp70表达差异是否影响诱导性耐热性，这是Hsp70的主要生物水平表型；(3)通过特异性核糖核酸酶保护试验确定TEs是否破坏hsp70反激活[hsp70编码基因的转录]；(4)测量te破坏hsp70Ba启动子是否如预测的那样，增强了未经历热应激的果蝇的适应性。该研究将整合分子遗传学、生物化学和生理学方法，并首次阐明种群内调控序列变异与表型多样化之间的联系。

Dissertation Research: Evolutionary Physiology of Heat-Shock Gene ExperessionDr. Martin E. Feder & Daniel LermanThe proposed research will investigate a remarkable case in which transposable elements [TEs, pieces of DNA that have the ability to move from one place to another within the genome] have repeatedly but independently disrupted the promoter [region controlling transcription] of a gene encoding an inducible molecular chaperone [a protein that prevents or alleviates damage to other proteins; e.g., Hsp70], which in turn should affect tolerance of environmental stress and fitness. This system has great promise as a model for investigating how large-scale differences in physiological traits arise from minor variation among individuals within populations. Prior research has discovered 3 independent instances in which, in natural populations of the fruit fly Drosophila, TE insertions disrupt the spacing between heat-shock response elements in the hsp70Ba proximal promoter; each such population exhibits distinctive Hsp70 protein levels. For each population, the proposed research will develop replicate lines with which to: (1) Quantify Hsp70 protein levels to test whether flies with TE-disrupted promoters express less Hsp70; (2) Determine whether TE-driven differences in Hsp70 expression affect inducible thermotolerance, a principle organism-level phenotype of Hsp70; (3) Determine, via specific ribonuclease protection assays, whether the TEs disrupt hsp70 transactivation [transcription of the Hsp70-encoding gene]; (4) Measure whether, as predicted, TE-disruption of the hsp70Ba promoter enhances fitness in Drosophila not undergoing heat stress. The proposed research will integrate molecular genetic, biochemical and physiological approaches, and be among the first to elucidate the link between intrapopulation regulatory sequence variation and phenotypic diversification.