Part I. Mutant Isolation and Gene Cloning. Isolation of DNA Structure-dependent Checkpoint Mutants in S. pombe, Rui G. Martinho and Antony M. Carr. Isolating Mutants of the Nematode Caenorhabditis elegans that are Hypersensitive to DNA-damaging Agents, Phil S. Hartman and Naoaki Ishii. Isolating DNA Repair Mutants of Drosophila melanogaster, Daryl S. Henderson. Generation, Identification, and Characterization of Repair-defective Mutants of Arabidopsis, Anne Britt and Cai-Zhong Jiang. Screening for y-ray Hypersensitive Mutants of Arabidopsis, Corinne Davies. Isolation of Mutagen-sensitive Chinese Hamster Cell Lines by Replica Plating, Margaret Zdzienicka. Strategies for Cloning Mammalian DNA Repair Genes, Larry H. Thompson. Novel Complementation Assays for DNA Repair Deficient Cells: Transient and Stable Expression of DNA Repair Genes, Lin Zeng, Alain Sarasin and Mauro Mezzina. Part II. Recognition and Removal of Inappropriate or Damaged DNA Bases. The Use of Electrophoretic Mobility Shift Assays to Study DNA Repair, Byung Joon Hwang, Vaughn Smider and Gilbert Chu. Mismatch Repair Assay, Stephanie Corrette-Bennett/ Robert S. Lahue. Analysis of Cyclobutane-pyrimidine-dimer and (6-4) Photoproduct Photolyases in Crude Extracts: Chromatographic and PCR-amplifiability assays, John Hays and Peter Hoffman. A Dot Blot Immunoassay for UV Photoproducts, Shirley McCready. Measurement of Ultraviolet Radiation-induced DNA Damage Using Specific Antibodies, Ann Stapleton. Quantification of Photoproducts in Mammalian Cell DNA Using Radioimmunoassay, David Mitchell. UV-endonuclease/ alkaline-sedimentation assay for Cyclobutane Pyrimidine Dimers in DNA from UV-irradiated Arabidopsis Plants, John B. Hays and Quishen Pang. DNA Damage Quantitation by Alkaline Gel Electrophoresis, Betsy M. Sutherland, Paula V. Bennett and John C. Sutherland. The Single Cell Gel Test (Comet Assay): A Sensitive Genotoxicity Test for the Detection of DNA Damage and Repair, G?nter Speit and AndreasHartmann.lC€