With the aim of understanding the process and mechanisms of molecular evolution, two related research projects are proposed. The first project is for studying the rates of nucleotide substitution among the four nucleotide A, T, C, and G for several different sets of genes and for developing mathematical models of nucleotide substitution that are more realistic than the ones currently available. The actual substitution rates will be estimated by the maximum parsimony method for closely related DNA sequences after the accuracy of the method is studied by computer simulation. The second project is concerned with the evolution of immune system genes in vertebrates and antigenic and nonantigenic genes in the influenza A virus. Since the DNA sequences for the genes for the major histocompatibility complex, immunoglobulins, and T-cell receptors (three major gene families of the immunoglobulin gene superfamily) are now available for many vertebrate species, including sharks and teleosts, the PI plans to study the origin and evolution of these gene families. We also plan to study the evolutionary history of various strains of the influenza A virus and the evolution of its pathogenicity.
