| Abstract | A mutant cell line (BU-54) of soybean (Glycine max L. Merr) capable of growing at a high rate in liquid suspension culture in 1 mg/ml of 5-bromodeoxyuridine (BrdU) has been isolated. The BU-54 cells have an active uptake system for thymidine (dT) and BrdU, and possess dT kinase which utilizes both substrates. Cesium chloride analysis showed that the BU-54 cells incorporated very little BrdU into DNA unless 5-fluorodeoxyuridine (FdU) was present. The BU-54 showed a high degree of resistance to FdU and aminopterin. The cells also contained approximately three times more deoxythymidine monophosphate synthetase and 50 times more dihydrofolate reductase than sensitive wild type soybean cells. The results support the conclusion that the BrdU resistant line may overproduce deoxythymidine monophosphate which could result in a reduced incorporation of BrdU into cellular DNA. |
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