title: Size heterogeneity of ribosomal RNA in eukaryote evolution--2. rRNA molecular weights in species containing discontinuous large ribosomal subunit RNA.
abstract: 1. The molecular weights and the integrity of the principal rRNA species derived from the large and small ribosomal subunit (respectively, L-rRNA and S-rRNA) of several species of Protostomia and Protozoa have been investigated. 2. Using gel electrophoresis in formamide, the molecular weights of protostomian L-rRNA species have been found to range from 1.30 X 10(6) (Annelida) to 1.61 X 10(6) (Diptera); those of the S-rRNA's cover the range 0.65 X 10(6) (Annelida)-0.81 X 10(6) (Diptera). 3. Both rRNA components have incurred extensive changes among the Protozoa; the L-rRNA ranges in weight from 1.35 X 10(6) (T. pyriformis) to 1.57 X 10(6) (A. castellanii) and the S-rRNA from 0.70 X 10(6) of T. pyriformis to 0.85 X 10(6) of A. castellanii and E. gracilis. 4. The L-rRNA components of all the species investigated are discontinuous molecules endowed with a latent median break; depending on whether the nick is located at the centre of the L-rRNA chain, or lies off-centre, the molecular weight of the S-rRNA equals that of either both, or only one, of the two fragments composing the L-rRNA.
mesh_terms: D000818:Animals; D002477:Cells / Q000032:analysis*; D004591:Electrophoresis, Polyacrylamide Gel; D056890:Eukaryota; D005057:Eukaryotic Cells / Q000032:analysis*; D046911:Macromolecular Substances; D008970:Molecular Weight; D010271:Parasites; D012335:RNA, Ribosomal / Q000032:analysis*; D013045:Species Specificity
chemical_list: D046911:Macromolecular Substances; D012335:RNA, Ribosomal