The use of drug-resistant markers to study the hybridization of mouse fibroblasts

Abstract

When 2 clonal sublines of mouse fibroblasts lacking either guanylic acid-inosinic acid pyrophosphorylase or thymidine kinase were grown together in mixed culture for 4 days, it was possible by a selective technique to detect hybrid cells at a frequency of 1 to 5 × 10-6. These hybrid cells contained approximately double the chromosome number and the DNA, RNA, and protein/cell of the parental cells, as well as both enzymes. During cultivation for about 1 year, 2 hybrid lines have lost an average of 8 and 9 chromosomes. So far it has not been possible to increase the frequency of hybridization nor the speed of chromosome loss. © 1966.