Extension of BrdU-dye analysis of DNA replication and sister chromatid exchange formation to in vivo systems : (in vivo, BrdU-dye, DNA replication, sister chromatid exchange)

BrdU-dye methodology was initially developed in tissue culture. Wide application of the technique for cytogenetic studies of DNA structure, replication and repair followed. Although the need for parallel in vivo studies was apparent, technical difficulties delayed the establishment of highly relevant BrdU-dye methods in intact mammals. Recently, BrdU-dye methods were adapted to in vivo rodent systems and the potential for diverse analyses of chromosome structure and function, comparable to those of in vitro analyses, demonstrated. In addition, the unique suitability of in vivo systems for studying replication kinetics and sister chromatid exchange formation in multiple tissues, inclusive of both somatic and germ cells, was shown. New in vivo protocols under development offer methodological simplicity and convenience of implementation. In vivo BrdU-dye techniques should thus afford an attractive alternative to in vitro systems for many cytogenetic studies.JAMES W. ALLEN, CHARLES F. SHULER, AND SAMUEL A. LATT, Clinical Genetics Division, Mental Retardation Program, Children's Hospital Medical Center and the Department of Pediatrics, Harvard Medical School, Boston, Massachusetts