DISSERTATION RESEARCH: The Genetic Basis of Adaptation in Thermally Adapted Escherichia Coli

论文研究：热适应大肠杆菌适应的遗传基础这个项目将采用基因组学的方法来理解对高温的适应。PI将检查大肠杆菌的种群，这是一种存在于所有哺乳动物肠道菌群中的微生物，已经在实验室中高温培养了2000代。他们将研究适应高温的遗传基础，适应高温的不同品系之间的并行进化程度，以及种群暴露在较低温度下时的可逆性表型和遗传变化。这项工作涉及三个主要目标。第一个目标是研究对高温的适应如何改变基因的拷贝数，要么通过复制增加拷贝数，要么通过缺失减少拷贝数。第二个目标是研究对温度的适应如何影响基因表达水平。最后，在不断变化的温度条件下，生物体如何在表型或生物体水平上做出反应，以及它们如何在遗传水平上做出反应？有什么特别的模式吗？生物体水平的变化总是由相同的基因变化引起的，还是多个基因变化可以产生相同的表型变化？DNA高密度阵列将用于筛选整个基因组的基因复制和缺失区域，并表征基因表达。这种全基因组方法是一个强大的工具，因为它允许同时筛选所有4290个大肠杆菌基因，使得不需要对所有4290个基因进行单独检查。这项工作之所以重要，是因为它开始剖析自达尔文时代以来引起比较生物学家和进化生物学家兴趣的复杂适应过程。

DISSERTATION RESEARCH: The Genetic Basis of Adaptation in Thermally Adapted Escherichia ColiAlbert Bennett and Michelle RiehleThis project will take a genomic approach to understanding of adaptation to high temperature. The PIs will examine populations of Escherichia coli, a microbe present in the intestinal flora of all mammals, that have been cultured in the laboratory for 2000 generations at high temperature. They will examine the genetic basis of adaptation to high temperature, the degree of parallel evolution among different lines adapted to high temperature, and the reversability phenotypic and genetic changes upon exposure of populations to lower temperatures. The work addresses three main goals. The first goal is to examine how adaptation to high temperature changes the copy number of genes, either increasing copy number via duplication or decreasing copy number via deletion. The second goal is to examine how adaptation to temperature affects the level of gene expression. Lastly, given changing thermal conditions, how do organisms respond on the phenotypic or organismal level and how do they respond on the genetic level? Is there a particular pattern? Are changes at the organismal level always caused by the same genetic change, or can multiple genetic changes yield the same change in phenotype? DNA high-density arrays will be used to screen whole genomes for regions of gene duplication and deletion, and to characterize gene expression. This whole genome approach is a powerful tool in that it allows the simultaneous screening of all 4290 E. coli genes, making individual examination of all 4290 genes unnecessary. This work is important because it begins to dissect the complex process of adaptation that has intrigued comparative and evolutionary biologists ever since the time of Darwin.