Informational molecules in amoebae studies of template utilization by the DNA polymerase activities of Amoeba...

Studies have shown that certain strain-specific characters of large, free-living amoebae may be influenced by the microinjection of non-homologous low molecular weight RNAs. To investigate the mechanisms involved in 'information' transfer, the template preferences of partially purified DNA polymerase activities isolated from Amoeba discoides have been studied. After passage through Sephadex G-200, DNA polymerase activities from whole homogenates could utilize both 'activated' calf thymus DNA and the synthetic ribohomopolymer poly rA oligo d(pT)10 as templates. Fractionation using different saturations of (NH4)2SO4 showed that there was no detectable poly A d(pT)10-directed DNA polymerase activity in the extra-mitochondrial cytoplasm, and the ability to utilize this template appeared to be located in the nuclei. Nuclear protein passed through short (30 cm) columns of Sephadex G-200 showed DNA polymerase activities which could use both synthetic and natural RNA as templates, but little activity was detected when using longer (70 cm) columns, although DNA-directed DNA polymerase activities were more clearly defined. Use of DEAE-cellulose only revealed a low (1--3%) activity with poly A d(pT)10 compared to the activity observed using 'activated' calf thymus DNS. DNA polymerase activities of amoebae showed a response to added RNA templates which depended on the purity of the enzyme preparation, and the possibility that these enzymes are involved in 'information' transfer cannot be ruled out.