Reiteration of DNA complementary to a cytoplasmic non-ribosomal RNA

Experimentally induced granulomas, in guinea pigs, were fractionated into a 40,000xg pellet and supernatant, which was further fractionated into a 100,000xg pellet and supernatant. The product of in vitro amino acid incorporation by the 40,000xg pellet was tentatively identified as collagen by its high proline/leucine ratio, its digestibility by bacterial collagenase and its solubility in hot trichloroacetic acid. The 100,000xg pellet incorporated leucine much more efficiently than the 40,000xg pellet and the product was insoluble in hot trichloroacetic acid.Labeled RNA from the 40,000xg pellet formed hybrids with granuloma ($\text{C}{}_{\mathrm{o}}\text{t}\text{1}\text{2}\text{= 100–150}$) and liver ($\text{C}{}_{\mathrm{o}}\text{t}\text{1}\text{2}\text{= 8,000}$) $\text{chromatin}$ DNA, indicating that genes coding for this RNA are repeated about 100-fold in granuloma and less than 5 times in liver DNA. Under conditions of poly(A) binding, 50% of this labeled RNA is retained by filters. Digestion with ribonuclease and ribonuclease T₁, decreases binding efficiency by 75%.