Ecological and Evolutionary Physiology of the Stress Response and Stress Proteins

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The evolution of genes is critical for such diverse and important phenomena as bacteria acquiring resistance to drugs, viruses affecting human health, and species' sensitivity to global climate change. Factors determining how readily genes mutate - the first step in their evolution - are poorly understood. This research will follow up on an NSF-supported discovery that one class of genes, named heat-shock genes, are especially sensitive to mutation because transposable elements (DNA sequences capable of jumping from gene to gene) readily invade these genes in natural populations of the common fruit fly, Drosophila melanogaster. If this phenomenon and its significance are truly general, it should be found in many species. A first goal will be to use computer techniques to search for transposable elements in the heat-shock genes of many species whose genomes have now been sequenced and are available online. A second goal will be to search for transposable elements in the heat-shock genes of a different fruit fly species, Drosophla willistoni. As NSF-supported research has shown, if transposable elements are present they can affect the way the host gene functions. In natural populations, the transposable elements can insert in different places and be of different sizes, and sometimes multiple elements can be present in a single gene. A third goal will be to understand the consequences of such variation for the way the genes make proteins, and how changes in the proteins affect tolerance of stress, growth, and reproduction. Thus, this research may explain a species' ability to respond to environmental change. This project will also serve as a vehicle for training young scientists, educating scientists in other countries, and providing information on which other scientists can build.