STUDIES ON SOMATIC CELL MUTATIONS

Abstract

In order to establish a sensitive assay system for the mutagens and to understand the nature of the differences in the mutation frequency among various somatic mammalian cell lines at various genetic markers reported by many workers, we examined the frequency of the forward and reverse mutations induced by X- and UV-irradiation, by using 8-azaguanine (8AG)-sensitive cells (prototrophic CH-hai Cl 23 cells) isolated from an original Chinese hamster hai cell line and 8AG-resistant cells isolated from CH-hai Cl 23 cells. However, both the mutation systems, especially the forward mutation system used here, were less sensitive as the assay system of the mutations induced by X-rays or UV, compared with the nutritional forward mutation system used previously (Ban et al. 1976). These results underline the complexity of the study of mutagenesis using cultured mammalian cells, particularly because the induced mutation frequency in cultured cells is affected by the factors of the mutation expression time, the size of the cell inoculum, the concentration of the selective agent, etc.