A characterization of the ribonucleic acid and ribosomes of the Myxomycete Physarum rigidum

Plasmodium of Physarum rigidum A was grown in axenic shake culture at 24[degrees]C in a soluble semi-defined medium. Aliquots were removed at 24 hour intervals and measured for dry weight, protein and RNA content. By day 13, the maximum values were reached. These were 85.0, 51.0 and 8.3 mg, respectively, per 50 ml of media. Extracts were made in a pH 7.4 buffer containing 0.01 M Mg[raised ++] ions, and the S[degrees][lowered 20] value of the ribosomes was determined to be 79.6. The magnesium concentration was lowered and the S[lowered 20] values of the subunits were determined to be 37.6 and 57.5 respectively. The sedimentation values of phenol purified total RNA were obtained using the analytical ultracentrifuge and absorption optics. The boundaries found had S[degrees][lowered 20] values of 5.1, 17.7 and 26.8. The nucleotide composition of the total RNA and ribosomal RNA was determined on multiple samples by chromatography on AG1-X8 formate resin following alkaline hydrolysis. The total RNA content of guanylic, cytidylic, adenylic, and uridylic acids respectively is 33.67[plus-minus]0.99, 18.82[plus-minus]0.60, 24.09[plus-minus]0.70, and 23.42[plus-minus]0.36. The corresponding composition of ribosomal RNA is 31.62[plus-minus]1.18, 19.33[plus-minus]1.29, 26.25[plus-minus]0.42, and 22.80[plus-minus]0.67.