ABSENCE OF DIFFERENTIAL RNA SYNTHESIS BY THE X CHROMOSOMES OF COW LEUCOCYTES

Abstract

The patterns of ribonucleic acid synthesis by the two X chromosomes during mitotic interphase were studied at metaphase. Cultured cow leucocytes were pulsed with H³-uridine for 15 minutes, washed, resuspended in tracer-free medium and collected at different times after the end of the pulse. Autoradiography of the cells failed to show any significant differences in the number of grains located over the two X chromosomes. The incorporation of H³-uridine into RNA by both X chromosomes indicates that at least part of the 'inactive' X chromosome must be actively synthesizing some RNA.