Mode of Action of Flucytosine in Aspergillus Species
The mode of action of flucytosine (5-FC, 5-fluorocytosine) in Aspergillus fumigatus and Aspergillus niger was studied. Pyrimidines, purines and nucleosides were found to have an antagonistic effect on 5-FC activity and evidence for a common purine-pyrimidine uptake system was found. Only a small amount, 7 to 17 per cent, of 5-FC taken up by the aspergilli was incorporated in RNA and none was incorporated in DNA. DNA content of cells grown in the presence of 5-FC was from 4 to 10 times that of control cells. These data are not compatible with the scheme proposed for the mode of action of 5-FC in yeasts and it is suggested that 5-FC in the Aspergilli may inhibit DNA synthesis.
KeywordsAspergillus Pyrimidine Thymidine Purine Nucleoside
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