The present project embraces the following aims: (1) To gain a general understanding of the biochemical and genetic mechanisms controlling the synthesis, repair and recombination of DNA. (2) To establish the function of genes that are essential for the continuation of DNA replication after it is initiated. (3) To elucidate the role of phage and host functions in the mechanism by which the monomer DNA of early T4 replicative stage is converted into the concotemer DNA of the late replicative stage. (4) To shed light on the mechanism by which growth factors initiate DNA synthesis in mammalian cells. (5) To comparatively study the control of deoxyribonucleotide biosynthesis in normal mammalian cells and their chemical transformed counterparts.