DISSERTATION RESEARCH: Alcohol dehydrogenase in Drosophila: Functional characterization of adaptive genetic variation

生物体如何适应环境是生物学中的一个基本问题，探索这一过程可以丰富我们对塑造形式，功能和物种进化的因素的理解。研究适应性特征的一种精确方法是通过实验来描述基因驱动进化的机制。这种方法可以揭示DNA水平的变化如何随着时间的推移影响功能的一般原则。在这里，这个框架被用来严格描述果蝇的酒精耐受性，这是一个经典的适应性进化模型。研究人员将调查一个长期存在的关于适应乙醇的假设，以及遗传、生物化学和生理水平上变异的关系。这项工作将展示如何在进化背景下部署生物化学方法，以产生新的见解。该项目的更广泛的影响包括在进化生物化学的新兴学科的研究生的培训，以及与当地高中教师合作，设计，目前，并公开分发一个教育模块，强调生物化学和进化遗传学的接口。黑腹果蝇中乙醇脱氢酶（ADH）的进化是适应的一个标志性例子：ADH的种间和种内变异分别具有正选择和平衡选择的特征，过去的工作已经假设了负责任的选择力。ADH上的正选择信号被认为反映了蛋白质进化对扩展和适应富乙醇环境的反应。黑腹菌本研究利用蛋白质的祖先序列重建、转基因生物的生化表征和生理测定来测试ADH是否如预测的那样发生功能变化。平衡选择的特征--由各大洲的重复和动态等位基因频率倾向支持--被认为是由于等位基因与温度的相互作用。本项目研究温度相互作用作为一种机制的作用。它将通过描述自然等位基因在环境现实温度下错误折叠的倾向来测试温度如何塑造遗传变异模式的假设。这些实验将具有广泛的意义，利用详细的，机械的研究在进化的背景下，阐明有关适应的功能决定因素的一般见解的方法学范例。

How organisms adapt to environments is a fundamental question in biology, and exploring this process can enrich our understanding of factors that shape the evolution of forms, functions, and species. A precise way to study adaptive traits is by experimentally characterizing the mechanisms through which genes drive evolution. This approach can reveal general principles about how changes at the DNA level affect function over time. Here, this framework is used to rigorously characterize alcohol tolerance in fruit flies, a classic model of adaptive evolution. The researchers will investigate a long-standing hypothesis about adaptation to ethanol and the relationship of variation at genetic, biochemical, and physiological levels. This work will demonstrate how biochemical methods can be deployed in evolutionary contexts to yield novel insights. Broader impacts of this project include training of a graduate student in the emerging discipline of evolutionary biochemistry as well as collaboration with local high school teachers to design, present, and publicly distribute an educational module emphasizing the interface of biochemistry and evolutionary genetics. The evolution of alcohol dehydrogenase (ADH) in Drosophila melanogaster is an iconic example of adaptation: inter- and intraspecific variations in ADH harbor signatures of positive and balancing selection, respectively, and past works have hypothesized the responsible selective forces. The signature of positive selection on ADH is thought to reflect protein evolution in response to expansion and adaptation to ethanol-rich environments by D. melanogaster. This research utilizes ancestral sequence reconstruction of proteins, biochemical characterization, and physiological assays of transgenic organisms to test if functional changes occurred in ADH as predicted. The signature of balancing selection - supported by recurrent and dynamic allele frequency clines across continents - is thought to be due to allele-by-temperature interactions. This project investigates the role of temperature interactions as a mechanism. It will test a hypothesis about how temperature might shape patterns of genetic variance by characterizing the propensity of natural alleles to misfold at environmentally realistic temperatures. These experiments will have broad significance as methodological exemplars of utilizing detailed, mechanistic studies in evolutionary contexts to elucidate general insights pertaining to the functional determinants of adaptation.