(CIT): Dr. Samuel Wilson, Deputy Director NIEHS and Head, Enzymology Section, Laboratory of Structural Biology, NIEHS describes his studies of the base excision repair enzyme, beta polymerase. From protein purification in the 1970's through gene cloning in the 1980's, crystallography in the 1990's to current studies of its actions in living cells, he provides first hand obstervations and commentary on the close linkage of development of technology to scientific progress in studies of DNA repair The DNA Repair Interest Group is concerned with all forms of DNA damage and repair. As a major defense against environmental damage to cells DNA repair is present in all organisms examined including bacteria, yeast, drosophila, fish, amphibians, rodents and humans. The members of the DNA Repair Interest Group perform research in areas including DNA repair enzymology and fine structure, mutagenesis, gene and cell cycle regulation, protein structure, and human disease.