Paper disc estimation of radioactive RNA: Studies on the presence and elimination of metabolically generated artifacts from labeled purine and pyrimidine precursors

Abstract

Conventional usage of the filter-paper disc technique following in vivo hepatic incorporation of certain labeled pyrimidine and purine RNA precursors resulted in the presence of radioactivity on the filter disc in species other than RNA. Thus the filter paper disc technique, conventionally conducted, may be misleading. To eliminate artifacts, it is proposed that replicate filter discs be processed, one group passing through the usual cold TCA washings only, while a parallel group of replicate discs are heated for 20 min at 90°C in 5% TCA to remove RNA. True RNA radioactivity is the difference of counts from the cold TCA precipitable material and the radioactivity remaining after hot TCA extraction.