Proper development of eukaryotic organisms requires differential expression of a multitude of genes with precise timing and tissue selectivity. Dr. Singleton is utilizing the developmental program of the cellular slime mold, Dictyostelium discoideum, as a system to investigate the molecular details of differential gene expression and the developmental regulation of this expression. He has identified and characterized three groups of genes which show various forms of differential expression upon the onset of development or shortly thereafter. Two groups are deactivated upon initiation of development, and the mechanisms of the deactivation events are very different between the two groups. A third set of genes is induced as development begins and is transiently expressed during the first few hours of the program. Dr. Singleton's analysis of mutant strains unable to develop has led to subclassification of the genes into those that appear to be under the same regulatory system. He will continue to isolate the genomic clones corresponding to certain of these genes and utilize them to investigate the molecular events involved in their regulation. The sequences necessary for transcription and proper regulation will be defined, and the protein factors which mediate the regulatory events will be identified and characterized. A system for generating and identifying mutations present in the genes encoding the regulatory machinery will be developed. Finally, through mutagenesis of a selected gene, he will begin to address what role these genes play in the establishment of the developmental program. %%% These investigations should result in a more comprehensive picture of the complexity and the details of the regulatory events leading to the activation and establishment of development using a simple model system. They will provide significant insight into the molecular machinery that is utilized in the control processes of early development.
