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Amplification and loss of dihydrofolate reductase genes in a Chinese hamster ovary cell line

Journal Article · · Mol. Cell. Biol.; (United States)
During stepwise increases in the methotrexate concentration in culture medium, the authors selected Chinese hamster ovary cells that contained elevated dihydrofolate reductase levels which were proportional to the number of dihydrofolate reductase gene copies (i.e., gene amplification). The authors studied the dihydrofolate reductase levels in individual cells that underwent the initial steps of methotrexate resistance by using the fluorescence-activated cell sorter technique. Such cells constituted a heterogeneous population with differing dihydrofolate reductase levels, and they characteristically lost the elevated enzyme levels when they were grown in the absence of methotrexate. The progeny of individual cells with high enzyme levels behaved differently and could lose all or variable numbers of the amplified genes.
Research Organization:
Dept. of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139
OSTI ID:
5877538
Journal Information:
Mol. Cell. Biol.; (United States), Journal Name: Mol. Cell. Biol.; (United States) Vol. 1:12; ISSN MCEBD
Country of Publication:
United States
Language:
English