Adaptive Mutations: A Consequence of Prokaryotic Differentiation

内华达大学拉斯维加斯分校的Ronald Yasbin博士因研究提高革兰氏阳性细菌枯草芽胞杆菌突变率的细胞分化过程和遗传机制之间的相互作用而获奖。新达尔文理论在很大程度上依赖于随机突变过程的能力，以提供进化过程继续所必需的相当数量的遗传多样性。然而，从数学模型和轶事观察中可以清楚地看出，完全随机的突变不可能在现有的时间内提供所有必要的事件，使我们从一些非常简单的生命形式发展到人类眼睛的复杂性。因此，在孟德尔遗传学的合法范围内解释必要的遗传多样性的问题就存在了。在过去几十年中，已经观察到作为自然遗传过程重要组成部分的多样性产生机制的许多例子。DNA已被证明是可移动的，细胞已被证明能够提高突变率以应对环境挑战。当细胞以双链DNA的形式复制或复制它们的遗传物质时，已经证明在新的遗传物质中发生突变的速率从一条链到另一条链并不是恒定的。此外，有研究表明，将DNA中包含的遗传信息转化为蛋白质的过程也会显著影响突变率和产生突变的位置。该项目探索了提高突变率和潜在影响突变发生位置的其他遗传机制。因此，研究人员利用枯草芽孢杆菌的三个已被充分表征和完全测序的基因来研究在环境胁迫期间产生突变的机制。目的是确定这些突变是否在细菌的一个亚群中产生，这些亚群已经分化，以便在培养中产生必要的遗传多样性。突变频率的分析和由此产生的菌落正在进行数学建模。因此，该项目代表了分子生物学家/遗传学家和统计学家之间的积极合作，并包含非常重要的教育组成部分。

An award is being made to Dr. Ronald Yasbin of the University of Nevada Las Vegas to study the interaction between processes of cellular differentiation and genetic mechanisms for enhancing mutation rates in the Gram Positive bacterium, Bacillus subtilis. Neo-Darwinian theory has counted heavily upon the ability of the random mutagenesis processes to provide a considerable amount of the genetic diversity necessary for the evolutionary process to continue. However, it is clear from both mathematical modeling as well as just anecdotal observations that completely random mutagenesis could not have provided all of the necessary events to have gotten us from some very simple form of life to the complexity of the human eye in the amount of time that has been available. The problem therefore exists as to explain the necessary genetic diversity within the legitimate confines of Mendelian genetics.During the last few decades numerous examples of diversity generating mechanisms, that are important parts of the natural genetic process, have been observed. DNA has been shown to be mobile and cells have been demonstrated to be capable of enhancing their mutation rates in response to environmental challenges. As cells replicate or duplicate their genetic material, in the form of double stranded DNA, is has been demonstrated that the rate at which mutations occur in the new genetic material is not constant from one strand to other. Furthermore, it has been suggested that the processes that exist to translate the genetic information contained in the DNA into protein can also significantly effect mutation rates and the location of generated mutations. This project explores additional genetic mechanisms for enhancing mutation rates and for potentially influencing in where the mutations will occur. Accordingly, three well characterized and fully sequenced genes of the B. subtilis are being used to investigate the mechanisms that generate mutations during periods of environmental stress. The goal is to determine whether or not these mutations are being generated in a subpopulation of the bacteria that have been differentiated in order to generate essential genetic diversity within the culture. The analysis of the mutation frequencies and the resultant colonies are being subjected to mathematical modeling. Accordingly, this project represents an active collaboration between molecular biologists/geneticists and statisticians and contains a very important educational component.