Mutation of human lymphoblasts by methylnitrosourea |
| |
Authors: | W.G. Thilly J.G. DeLuca H. Hoppe B.W. Penman |
| |
Affiliation: | Department of Nutrition and Food Science, Massachusetts Institute of Technology, Cambridge, Mass. 02139 U.S.A. |
| |
Abstract: | The lag in phenotype expression of methylnitrosourea(MNU)-induced mutation to 6-thioguanine (6TG) resistance has been studied in a diploid human lymphoblastoid cell line. We find that a considerable period (8–12 days) elapses before new mutants appear in treated cultures; after 2 weeks, however, a stable maximum fraction is attained, as would be expected for a genetic mutation. We present preliminary data linking this phenotypic lag to the slow degradation rate of hypoxanthine-guanine phosphoribosyl transferase (HGPRT) and to an apparent requirement for very low (<0.2% normal) cellular HGPRT content in order for cells to be resistant to 10 μg 6TG/ml. A series of reconstruction experiments are presented, the results of which support the conclusion that selective pressures in the assay procedure do not bias the quantitative estimates of induced mutant fraction. |
| |
Keywords: | HGPRT hypoxanthine-guanine-phosphoribosyl transferase MNNG methylnitrosonitroguanidine MNU methylnitrosourea PBS phosphate-buffered saline PRPP phosphoribosylpyrophosphate 6TG 6-thioguanine |
本文献已被 ScienceDirect 等数据库收录! |