RAPIDLY LABELED NUCLEAR AND CYTOPLASMIC RENAL RNA

Much of the RNA in mouse kidneys is not recovered when they are extracted with phenol-SDS at 60°C. Better recovery is achieved by extracting in hypertonic buffer with phenol-SDS, chloroform, and isoamyl alcohol after treatment with DNase. 1. Among the polydisperse RNA in the renal nuclei are small amounts of 45S RNA and large amounts of 32S RNA; the latter first appear when 18S RNA is detectable in the cytoplasm 10 min after administration of undine-H(3). 2. In the cytoplasm rapidly labeled 18S RNA is transported as part of a 45S particle to which mRNA is attached. 3. Compared to HeLa cells in culture, normal mouse kidney is poor in the polydisperse nuclear precursors of rRNA and rich in the cytoplasmic polydisperse RNA that sediments like mRNA.