Abstract
Summary
Amethopterin, a folic acid antagonist, has been found to prevent multiplication of HeLa cells in Eagle's medium containing added adenine and glycine. This inhibition can be removed by addition of thymidine or thymidylic acid. The amethopterin-induced thymine deficiency specifically results in a cessation of cell division and a disparate increase in cellular RNA and protein to DNA content. Ability of amethopterin-induced thymine deficient cultures to support viral synthesis appears to be dependent upon the type of nucleic acid contained in the virus. With DNA-containing viruses such as vaccinia and herpes simplex, viral replication is inhibited, whereas the synthesis of a RNA-containing virus such as poliovirus is not.
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