RAPIDLY LABELED FRACTIONS OF RIBONUCLEIC ACID IN BACILLUS MEGATERIUM

Abstract

B. megaterium strain KM proto-plasts, labeled with uridine or guanine for 1 to 10 min., were shocked osmotically and centrifuged, and the resulting pellet, presumably com -posed of cell membranes and nuclear material, was extracted with cold buffer-magnesium chloride (0.01 [image])-azide. The most rapidly labeled ribonucleic acid (RNA) seen was in the extract, largely in ultracentrif-ugal particles. It showed turnover in pulse experiments. The deoxy-ribonucleic acid (DNA) also appeared in this fraction, but the RNA-containing particles were not destroyed by removal of the DNA with deoxyribonuclease. Results are discussed in terms of possible nucleo-cytoplasmic RNA transfer. The principal ribosomal and soluble RNA fractions were also separated by ultracentrifugation for 2 hours. The supernatant fraction incorporated uridine and guanine more rapidly than the pellet fraction.