MOLECULAR-WEIGHT OF RIBOSOMAL-RNA PRECURSOR MOLECULES AND THEIR PROCESSING IN HIGHER-PLANT CELLS

  • 1 January 1979
    • journal article
    • research article
    • Vol. 34  (3-4) , 253-258
Abstract
Actively dividing callus cells of higher plants (Petroselinum crispum, Daucus carota, Acer pseudoplatanus) were used to detect the primary gene product of rDNA in vivo. Parsley and carrot cells were labeled with [32P]orthophosphate. Under non-denaturing conditions, in both cases, only 1 high MW rRNA precursor was present on polyacrylamide gels. Its MW did not exceed 2.5 .times. 106 dalton. Under denaturing conditions, 2.0-2.1 .times. 106 dalton were determined on formamide gels. This rRNA precursor was already present after a labeling period of 5-10 min. In labeled parsley cells mature rRNA (25S and 18S) arrived in the cytoplasm 45 min after onset of incubation. In A. pseudoplatanus incubated with [3H] uridine 2 rapidly labeled components did emerge from polyacrylamide gels without formamide; their MW were 2.3 and 3.2-3.4 .times. 106 dalton. After electrophoresis in formamide, the larger component disappeared, indicating that it would be an intermolecular aggregate of different RNA. There was no evidence for the existence of rRNA precursors exceeding the MW of 2.5 .times. 106 dalton.