Changes in RNA Synthesis Following Transfer of Sarcoma 180 Ascites Cells from the Mouse to Synthetic Medium1

RNA synthesis in Sarcoma 180 ascites cells growing in vivo in mice was compared to RNA synthesis in Sarcoma 180 cells following transfer to synthetic medium. Following radioactive labeling of Sarcoma 180 cells, RNA was extracted with phenol and fractionated on methylated bovine serum albumin columns. The cells appeared to experience a nutritional shift with resulting cessation of ribosomal RNA synthesis following transfer to syn thetic medium. Pulse-labeling experiments with transferred cells demonstrated the synthesis of a rapidly labeled, high molecular weight RNA fraction which did not appear to be ribosomal RNA precursor. Comparisons of base compositions showed that ribo somal RNA synthesis in ascitic cells 15 hr after transfer to syn thetic media was still different to that observed following growth ¿wvivo.