Chromosome Synthesis

Summary

Autoradiographic studies, based on tritiated uridine incorporation into pulverized chromatin, induced in fused cells of the Chinese hamster cell line Don by treatment with ultraviolet-inactivated Sendai virus, were performed to elucidate RNA synthetic activity in pulverizations. Incorporation of uridine into pulverized nuclei was observed in nearly 80% of the pulverizations during the first 20 minutes after virus addition. However, during the last 20 minutes of a 40-minute incubation after virus addition, only 15–35% of the pulverizations were labeled. A few labeled pulverizations were believed to have synthesized RNA before the cells fused. The low incorporation of uridine was due to loss of RNA synthetic capacity and not to leakage or breakdown of the RNA during preparation of the slides.