STUDIES ON RNA METABOLISM IN ACETABULARIA MEDITERRANEA .I. ISOLATION OF RNA AND LABELLING STUDIES ON RNA OF WHOLE PLANTS AND PLANT FRAGMENTS

1. 1. A method is described for the isolation of RNA from Acetabularia homogenates by precipitation with 2 M LiCl. Sucrose density-gradient centrifugation yields three major RNA species which possess approximate sedimentation coefficients of 24 S, 15 S, and 5 S, respectively. 2. 2. Studies on the kinetics of isotopic labelling disclose the existence in Acetabularia of two diverse RNA species: a rapidly labelled component sedimenting at 5 S, and a 15-S species, which incorporates [3H]uridine at a much slower rate. 3. 3. Absorbance profiles of nucleate algae reveal a striking diminution of the 15-S fraction 7 days after enucleation. The absorbance patterns of 1-month anucleate and nucleate fragments are somewhat unusual: the 24-S peak disappears in both types of fragments, and there is a reduction of the 15-S component in nucleate halves. Absorbance profiles of whole plants with caps display the same changes as 1-month nucleate algae. © 1969.