We propose to apply a molecular and genetic approach to identify the genes that function in a signal transduction pathway that regulates a gene critical for development. The transcriptional regulation of the cyclic nucleotide phosphodiesterase in the early development of Dictyostelium discoideum will be investigated through the analysis of existing and new regulatory mutations. The following approaches will be pursued. 1) The defects in two pds A mutations that specifically alter regulation of the phosphodiesterase will be identified. 2) We will develop a suicide selection method that utilizes extrachromosomal shuttle vectors to isolate new regulatory mutations that are specific for the phosphodiesterase gene. 3) Genetic complementation analysis will be performed with the new and existing mutations to elucidate the activities involved in the developmental regulation of the phosphodiesterase gene. Our approach should complement the work of others studying receptor-mediated events of signal transduction to identify molecules that link the members of a signal transduction chain into a pathway from the cell surface to the nucleus. //
