Species of DNA polymerases Alpha, Beta, and Gamma from cultured human fibroblasts and HeLa cells will be fractionated and studied with regard to fidelity, catalytic properties, and function. Particular emphasis will be put upon changes that occur during late passage numbers of fibroblasts or during growth to confluence. Antibody studies will be carried out for the Alpha-species, in order to attempt to design affintiy columns for purification and to understand the significance and commonalities of the various Alpha-subspecies. The human polymerases will be tested upon various substrates in order to ascertain their role in DNA repair and to identify factors that may work with the polymerases in this capacity. E. coli DNA polymerases will also be studied. A new species of polymerase I that appears after recA induction will be characterized and the activities of polymerases II and III upon various damaged substrates will be ascertained.