Effect of mitomycin C on thymidine-methyl-H3 utilization by Entamoeba histolytica propagated in CLG medium.

Abstract

SYNOPSIS. Autoradiographic studies were done which tested the effect of a potent DNA inhibitor, mitomycin C (MC) on the utilization of tritium from exogenous thymidine‐methyl‐H3 (TMH3) in Entamoeba histolytica grown with Bacteroides sp. in CLG medium. Concentrations of MC (0.0002%) which inhibited growth of amebae by ca. 50%, caused an overall depression of tritium utilization by both associate cell and amebae. However, no reduction in percent cells with nuclear activity was apparent.The effect of MC on utilization of tritium in amebae propagated with Bacteroides which were prelabeled with TMH3 was also studied. The extent of labeling and percent amebae with cytoplasmic label was not appreciably depressed by MC. MC did, however, cause a depression of the percent amebae with nuclear label. This would indicate that the utilization of bacterial DNA products for nuclear DNA (reported in a previous communication) is reduced in the presence of MC. These data on the effect of MC on use of exogenous TMH3 and prelabeled Bacteroides provide some evidence that at least some of the nuclear DNA of amebae can be synthesized from the exogenously supplied isotope.Amebae grown with exogenous TMH3 and resuspended in unlabeled medium for 24–28 hrs. with and without MC had a considerable reduction of the extent of label whether MC was present or not. This suggests that the primary effect of MC is not to degrade DNA.