Chromosome-mediated gene transfer between closely realted strains of cultured mouse cells.

Abstract

Gene transfer between 2 closely related mouse cell lines [501-1, a chloramphenicol-resistant; hypoxanthine aminopterin and thymidine [HAT] sensitive, 8-azaguanine (AZ) resistant, hypoxanthine-guanine phosphoribosyl transferase deficient cell line and H29 cells, HAT resistant, AG resistant] was carried out, using as the vector a cell-free preparation of metaphase chromosomes and nuclei. Distinction between gene transferents and revertants of the recipient mutant phenotype was achieved by the use of a donor strain carrying a mutationally altered (8-azaguanine-resistant) hypoxanthine-guanine phosphoribosyltransferase (HPRTase; IMP:pyrophosphate phosphoribosyltransferase, EC 2.4.2.8). The transferred HPRTase gene is initially unstable; in nonselective medium, it is lost at a rate of about 0.1/cell per generation. Stabilization occurs as a rare event, with a frequency on the order of 1 .times. 10-5/cell per generation. The unstable state can be maintained for at least 200 generations through serial passages of the transferent in selective medium. Under the conditions of cultivation used in these experiments, the unstable HPRTase-positive cells are eventually replaced by the stable HPRTase-positive cells in the population.