| Abstract: | A method is described for sedimenting RNA on a preparative scale in the presence of 85% formamide. It is likely that the RNA is fully denatured, since under the same conditions ribosomal RNA develops full hyperchromicity, and formaldehyde-treated and untreated ribosomal and nuclear RNA sediment in an identical manner.RNA from immature duck red blood cells was fractionated on sucrose gradients. The amount of hemoglobin mRNA and poly(A) in each fraction was measured by hybridization with complementary DNA and poly(U), respectively. We observed that hemoglobin mRNA forms aggregates in the presence of phenol, which are dispersed on formamide gradients. Nuclear RNA became more heavily aggregated, and again the aggregates were dispersed by formamide. A possible nuclear precursor of hemoglobin mRNA was identified. The molecular weight of the precursor is 6–7 × 105, three times as long as hemoglobin mRNA, and it is attached covalently to a poly(A) sequence. |
