The two items of equipment here requested, a source of ionizing radiation and a computerized karyotyping system, will be shared by researchers in a program aimed at understanding basic genetic mechanisms in the cells of animals and how these control life processes including maintenance of correct biochemical conditions, growth, differentiation and development, and cell-cell interactions. The research programs are focused on understanding basic biochemical and genetic mechanisms of mutation and DNA repair, the role of cyclic AMP in genetic regulation, elucidation of the arrangement of genes on chromosomes and relationships of this topography to gene expression and the regulation of biochemical pathways. The approach is such that each of the laboratories share many common methodologies. Each, for example, employs somatic cell genetics, biochemistry, and recombinant DNA technologies, that require common facilities and equipment such as those requested here.