The overall objectives of the research project are to develop new selective methods in somatic cell genetics for the studies of (1) human gene mapping, (2) the regulation of gene expression, and (3) the mechanism of herpes viral transformation. The selective markers are deoxcytidine deaminanse (dCD), adenosine kinase (AK) and adenosine deminase (ADA). I have obtained a mouse cell line deficient in adenosine kinase and hybridized the mutant cells with wild-type human cells. These AK plus hybrids and their AK minus sublines will be used for mapping of human adenosin kinase gene. A mutant line of mouse fibroblast was obtained which contained about 10 percent of adenosne deaminase activity of wild-type cells. This line will be hybridized with human wild-type cells and resultant hybrid cells used for genetic analysis of human adenosine deaminanse. I found that herpes simplex virus type I (HSV-I) induced dCD activity in a mouse cell line deficient in dCD. The induced enzyme is presumably coded by the viral genome since it has different electrophoretic mobility. I will characterize this enzyme further with an immunological method. I will also transform the dCD- minsus cells with UV- inactivated virus and isolate dCD plus transformants in the HAM selective medium (hypoxanthine, aminopterin and 5 methyldeoxycytidine). Human mouse hybrids selected for the presence of human AK or ADA would be useful for human gene mapping experiments, as well as for the studies of two human diseases: hereditary hyperuricemia (gout) and a severe combined immunodeficiency disease. Studies on gene transfer mediated by HSV-I could elucidate the mechanism by which some oncogenic strains of herpes virus cause malignant transformation of mammalian cells. BIBLIOGRAPHIC REFERENCES: Chan, T.-s. and Creagan (1976): Human-mouse somatic cell hybrid lines selected for human adenosine kinase: a new selecitve method. Human Gene Mapping 3, Baltimore Conference. (in press). Chan, T-s., Model, P., Zinder, N. D. (1975). In vitro protein synthesis directed by separated transcripts of bacteriophage f1 DNA J. Mol. Biol. 99:369-382.