[RNA synthesis in bone marrow hematopoietic stem cells]

The effect of inhibitors of DNA-dependent RNA synthesis (sibiromycin and actinomycin D) and radio toxic doses of 3H-uridine on the bone marrow stem hemopoietic cells in adult mice was studied by means of spleen colonies. The short-term in vitro preincubation of the bone marrow cell suspension with the antibiotics and 3H-uridine resulted in the practically complete inhibition of colony formation. The bone marrow stem hemopoietic cells incorporated 3H-uridine intensively. In the normal adult animals the number of stem cells with the high level of RNA synthesis attained 40% whereas the rest 60% of cells were capable to activate the ribonucleic metabolism upon their in vitro preincubation.