procollagen messenger ribonucleic acid ( mrna ) was isolated from the calvaria of 15-day-old chick embryos by chromatographing total rna over oligo ( dt ) -cellulose two times , and then fractionating the twice-bound rna on 85 % me2so/0-20 % sucrose gradients .
C0035696
messenger ribonucleic acid
C0035668
rna