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NATURAL SELECTION FOR TRANSPOSABLE ELEMENTS

转座元件的自然选择

基本信息

批准号：
3280476
负责人：
Lin CHAO
金额：
$ 6.19万
依托单位：
NORTHWESTERN UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
1983
资助国家：
美国
起止时间：
1983-04-01 至 1986-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/3280476
关键词：
Escherichia coli alleles bacterial DNA bacterial genetics bacteriophage P1 bacteriophage lambda endonuclease gel electrophoresis gene expression gene frequency genetic manipulation genetic mapping genetic recombination genetic regulation genetic strain natural selections nucleic acid sequence radiotracer

项目摘要

The genome of organisms as varied as bacteria, corn and fruit flies are known to harbor discrete autonomous sequences of DNA (transposable elements) which are capable of transposition to new sites within the genome (Nevers and Saedler, 1977; Calos and Miller, 1980; Starlinger, 1980; Kleckner, 1981: Green, 1980). Although much is known about their genetic and biochemical properties, little is known about their evolutionary origins. I present in this proposal a project aimed at testing the hypothesis that these elements might have evolved by conferring their host genome a selective advantage in the form of an increased mutation rate. I intend to examine this possibility by investigating competition between strains of Escherichia coli with and without specific transposable elements (Tn5, Tn10, and bacteriophages lambda and P1) in chemostat cultures. Transposition of these elements within the chemostat populations will be monitored via Southern blot hybridizations (Southern, 1975). The sites of new transposition will be analyzed genetically and mapped, with the final objective being to ascertain whether the new transpositions occur randomly or whether they are correlated with loci that confer a selective advantage in the chemostats. In preliminary experiments with Tn10, I have been able to detect transpositions and the results suggest that Tn10 does confer a selective advantage by creating beneficial mutations and allowing its host genome to evolve faster. The demonstration that transposable elements have evolved for the specific role of generating genetic variability would be significant. The phenomena of mutations, genetic rearrangements, or gene regulation are fundamental not only to evolution but also to other areas of biology. For example, many processes of both biological and medical interest (genetic disorders, acquisition or loss of virulence by pathogenic organisms, senescence, genetic or physiological adaptations) could all be directly related to an organisms's ability or failure to regulate its genes.

细菌、玉米和果蝇等生物体的基因组多种多样，已知含有离散的自主DNA序列（可转座的元件），其能够转座到基因组内的新位点（内弗斯和Saedler，1977年; Calos和米勒，1980年;史太林格，1980年; Kleckner，1981：绿色，1980）。尽管我们对它们的基因有很多了解，和生物化学特性，很少有人知道他们的进化起源. 我在这个建议中提出了一个项目，旨在测试假设这些元素可能是通过赋予宿主基因组以增加突变率的形式具有选择优势。我我打算通过调查具有和不具有特异性转座因子的大肠杆菌菌株 (Tn5、Tn 10和噬菌体λ和P1）。这些元件在恒化器群体内的转座将是通过Southern印迹杂交监测（Southern，1975）。的位点新的转座将进行遗传分析和映射，最终目的是确定新的换位是否随机发生或者它们是否与赋予选择优势的基因座相关在恒化器里在对Tn 10的初步实验中，我已经能够检测转座，结果表明Tn 10确实赋予了通过创造有益的突变，基因组进化得更快。证明转座因子具有为产生遗传变异的特定作用而进化的，显著突变、基因重排或基因突变现象监管不仅是进化的基础，也是生物学例如，生物和医学的许多过程感兴趣（遗传性疾病，致病性疾病获得或丧失毒力生物体、衰老、遗传或生理适应）都可能是直接关系到一个有机体的能力或失败，以调节其基因。