GENETIC BASIS OF SELECTION IN NATRUAL POPULATIONS

自然群体选择的遗传基础

• 批准号: 3277829
• 负责人: Daniel E. DYKHUIZEN
• 金额: $ 22.89万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1981
• 资助国家: 美国
• 起止时间: 1981-09-01 至 1991-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3277829
• 关键词: Escherichia coli; aldehyde dehydrogenases; alkaline phosphatase; alleles; aminoacid; beta galactosidase; biochemical evolution; biological polymorphism; electrophoresis; exopeptidase; gene mutation; genetic manipulation; genetic strain; genotype; glucose 6 phosphate isomerase; growth media; isomerase; microorganism culture; microorganism growth; molecular cloning; nucleic acid sequence; phosphoglucomutase; phosphogluconate dehydrogenase; regulatory gene; structural genes; transferase

This is the continuation of an ongoing project in the population genetics of E. coli, the objective of which is to determine the molecular mechanisms by which amino acid substitutions in enzymes affect the activity of the enzyme and the physiology and growth rate of the organism. Amino acid substitutions are derived from three sources -- (1) naturally occurring electrophoretic variants of gnd, pgi, zwf, and other genes; (2) variants created by site-directed mutagenesis or by the reversion of nonsense codons in the phoA and lacZ genes; and (3) mutants of gnd that result from selection for faster growing strains that arise in gluconate chemostats inoculated with a strain containing an edd mutation. Functional analysis of the variant enzymes includes characterization in terms of enzyme kinetics and especially differential growth rate in chemostats in which growth is limited by the availability of key substrates. These data will permit an evaluation of the proposed saturation model of enzyme evolution, in which it is predicted that many mutations that result in small changes in enzyme activity produce negligible changes in fitness. The project includes the development of a novel type of continuous culture device which permits fluctuations in the type or concentration of nutrient, in the expectation that nonequilibrium conditions may produce different results than equilibrium conditions. The proposal also includes extensive cloning and sequencing of gnd alleles from a critical set of natural isolates in order to evaluate the clone concept of population structure and to determine the extent of nucleotide variation in structural versus regulatory regions. Molecular analysis of gnd alleles selected in chemostats will also be carried out. Data and inferences derived from the proposed experiments will be important in evaluating the effects of naturally occurring genetic variants in other organisms and in predicting the functional effects of new mutations.

这是一个正在进行的群体遗传学项目的继续。 其目的是确定其分子机制。 酶中的氨基酸取代通过什么影响酶的活性 酶和生物体的生理和生长速度。氨基酸 替代来自三个来源--(1)自然发生 GND、PgI、zwf和其他基因的电泳变异体；(2)变异体 通过定点突变或通过无意义密码子的逆转而创建 在PhoA和lacZ基因中；以及(3)由以下原因导致的GND突变 葡萄糖酸盐类药物中生长较快菌株的选育 接种含有EDD突变的菌株。功能分析 变异酶的特性包括酶的特性 化学药物的动力学，特别是不同的生长速度 生长受到关键底物可获得性的限制。这些数据将 允许对所提出的酶进化饱和模型进行评估， 其中预测到许多导致微小变化的突变 酶的活性对健康的影响可以忽略不计。 该项目包括开发一种新型的持续文化 允许营养素的类型或浓度波动的装置， 在非平衡条件可能会产生不同的 结果比平衡条件要好。该提案还包括广泛的 天然GND等位基因的克隆和序列分析 以评估克隆概念的种群结构和 确定核苷酸在结构和结构上的变异程度 监管区域。中国人群GND等位基因的分子分析 此外，还将进行化学药物治疗。派生自 拟议中的实验将对评估 其他生物中自然发生的遗传变异及其在预测中的作用 新突变的功能效应。