Development of highly accurate analyzing system for radiation-induced chromosomal aberrations and mutations. Use of the chromosome painting method and transgenic systems

Aiming at a development of high-speed autoanalyzing system for radiation-induced chromosomal aberrations, development of a cell accumulation method for lymphocytes in metaphase was conducted in the first stage of this research. And a study on the establishment of screening techniques for mutants and analysis of the altered base sequences of mutants was made in the second stage. The optimum conditions for accumulation of lymphocytes in metaphase were investigated using six kinds of mitogenic agents and the combined use of PHA-M, PWM and SBA resulted in a higher mitotic rate than the respective single use and other combinations of them. In vitro x-ray exposure experiment revealed that a chromosome painting method using a DNA probe (Gibco BRL) is able to detect even a translocation and an insertion and it is more effective for monitoring chromosomal aberrations than the differential staining methods. Further, the characteristics of mutations induced by γ-ray exposure on E. coli gpt gene as a reporter gene were analyzed by DNA sequencer. For AS52 cell, a hamster transgenic cell with the gene, a large deletion was generated in 15 of 21 cells by the exposure. (M.N.)