Adaptive Mutations: A Consequence of Prokaryotic Differentiation

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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.