Single-strand breaks in DNA by 1-beta-D-arabinofuranosylcytosine and enhanced resistance frequency to N-phosphonoacetyl-L-aspartate.

1-beta-D-Arabinofuranosylcytosine (araC) caused concentration- and time--dependent single-strand breaks in SV28 cell DNA. Over the same concentration and time range, araC enhances the frequency of resistance to N-phosphonoacetyl-L-aspartate (PALA) and is also cytocidal (1). Comparison of induction of single-strand breaks by araC with its ability either to enhance the frequency of PALA-resistance or to kill cells, however, showed no obvious correlation, whether at different araC concentrations or exposure times. We conclude from these data that if there is a correlation between the ability of araC to cause single-strand breaks and either enhance PALA-resistance frequency or kill cells it is a complicated one or is masked by other events.