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Amplification of dihydrofolate reductase genes and their transfer to animal cells
- Institute of Bioorganic Chemistry, Academy of Sciences of the Uzbek SSR
A new subline of Chinese hamster cells BFFR3, derived from fibroblast-like cell line Blld-ii-FAF28 (431 clone), and resistant to 132 (μg/ml of metotrexate(mtx) has been described. Karyotype study has revealed the specific changes in resistant cells in the form of homogeneously stained within chromosomes 2 and 5, and at the same time single double minute chromosomes being amplified dihydrofolate reductase genes. Variation in the modal class of resistant cells is found in the process of selection, the cells with 24 chromosomes (40 %) being dominated. The transfer of drug resistance has been performed while treating mtx-sensitive FStk~ cells with DNA, isolated from resistant BFFB3 cells and the formation of colonies with low frequency (1.04-10~6) has been shown. Thus, the amplification of target-genes under action of mtx underlies variability of cell population.
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