Reverse genetic studies of homologous DNA recombination using the chicken B-lymphocyte line, DT40

DT40 is an avian leucosis virus-transformed chicken B-lymphocyte line which exhibits high ratios of targeted to random integration of transfected DNA constructs. This efficient targeted integration may be related to the ongoi ng diversification of the variable segment of the immunoglobulin gene throu gh homologous DNA recombination-controlled gene conversion. DT40s are a con venient model system for making gene-targeted mutants. Another advantage is the relative tractability of these cells, which makes it possible to disru pt multiple genes in a single cell and to generate conditionally gene-targe ted mutants including temperature-sensitive mutants. There are strong pheno typic similarities between murine and DT40 mutants of various genes involve d in DNA recombination. These similarities confirm that the DT40 cell line is a reasonable model for the analysis of vertebrate DNA recombination, des pite obvious concerns associated with the use of a transformed cell line, w hich may have certain cell-line-specific characteristics. Here we describe our studies of homologous DNA recombination in vertebrate somatic cells usi ng reverse genetics in DT40 cells.