Non-linkage of Induced Mutations in Chinese Hamster Cells

The relatively rapid loss of human chromosomes from human-rodent somatic cell hybrids has allowed the determination of linkage relationships between several human genes^1–4. Cells that have segregated out most of the human chromosomes are analysed for the presence or absence of particular human gene products; when two gene products are always found to be retained together, they are assumed to be linked. Little has been done to extend these genetic techniques to cell hybrids formed between two different mutants of the same cell line. A linkage analysis would provide a valuable means of interpreting the gene function altered in such mutants. The principal obstacle to such an approach has been the fact that homospecific cell hybrids are rather stable, losing chromosomes at only a low rate^5–7. Nevertheless, by using suitably marked strains, it is possible to select rare segregants from a homospecific hybrid population^7,8. I have applied such a system to test for linkage between several chemically induced mutations in a Chinese hamster cell line.