| Popis: |
Autoradiographic experiments were performed to localize and follow the different types of RNA (s-RNA, r-RNA, m-RNA) synthesized during the maturation of the oocyte. Similar results were obtained on the two different species studied (sea urchin, Xenopus). Incorporation of 3H-cytidine and 3H-uridine is observed in a preferential manner in the nucleolus and is inhibited by actinomycin D but not by puromycin. The latter, on the other hand, inhibits the incorporation of 5-methylcytosine observed in the cytoplasm (s-RNA). After maturation, the oocyte ribosomes are completely inactive. Puromycin inhibits 80% of the incorporation of phenylalanine into the oocyte proteins, while actinomycin has no effect on the synthesis of these proteins during growth. Nevertheless, actinomycin given during oogenesis seems to have an effect on the cleavage of the eggs, at the time of fertilization. These results are discussed and hypothesis proposed, to try and explain the role of this highly active RNA which is seen in the germinal vesicle of the oocytes, and the significance of the inertness of the ribosomes in the mature egg. |
