9623838 Riley A central assumption in the study of how mutation affects organisms is that the majority of mutations are harmful. This asqumption has never been experimentally tested. The goal of the research funded by this award is to test this assumption by determining the fate of novel genetic variation. Despite our current knowledge of the molecular biological processes which create mutation, little information is known about how or how much of the introduced variation is maintained in nature once a trait produced by the mutation is subjected to natural selection. To address this issue, Wagner and Riley will assess the effects of many different mutations on the viability and growth of bacteria, which are organisms that allow testing the effects of many kinds of mutations in a short period of time. A technique called random mutagenesis will be used to create many different mutated copies of a single gene in a bacterium, and the fraction of mutations that are beneficial, harmful, or have no effect will be determined. The exact chemical nature of the mutations from each of these three classes will be probed, to reveal whether there are particular types of mutations that are associated with benefit or harm to the organism. Using this information, it may then be possible for biologists to incorporate mutations of positive effect into beneficial organisms or harmful mutations into pest genotypes. Results may also facilitate the engineering of bacteria to perform certain functions, many of which may be useful in industrial processes.
