L'utilisation de nucléosides dans l'ovaire du Grillon et ses variations au cours de l'ovogenèse

OOCYTE DEVELOPMENT AND INCORPORATION OF H3- THYMIDINE AND H3-URIDINE IN PECTINARIA (CISTENIDES) GOULDII

“…During the growth or vegetative period of oocyte development in Pcctinaria there is a lack of thymidine incorporation into the germinal vesicle, a condition that extends at least to the metaphase of the first maturation division. This response is the same as that in oocytes of the sea urchin (Ficq et al, 1963b), the starfish (Geuskens, 1963), the sand dollar (Simmel and Karnovsky, 1961) and the cricket (Favard-Sereno and Durand, 1963b).…”

“…Further indication that H 3 -uridine was incorporated into nuclear and nucleolar RNA in the present study resulted when the nucleolar label in all oocytes and part of the nuclear label in most oocytes was removed when they were submitted to RNase prior to autoradiography. Similar autoradiographs of H 3 -uridine uptake into the nuclear sap and nucleoli of oocytes have been shown in the cricket ( Favard-Sereno and Durand, 1963a), the sea urchin (Ficq et al, 1963), the starfish Geuskens, 1963) and the toad (Ficq, 1964). The failure of RNase to remove the entire nuclear label from some of the larger, single oocytes of Pectinaria may be significant since H 3 -uridine may act as a precursor for DNA.…”

“…Generally, attempts to demonstrate cytoplasmic DNA in frog oocytes by autoradiography have been unsuccessful although Ficq (1961a) did find that the cytoplasm of non-dividing follicle cells became labeled but not the oocyte cytoplasm. In the cricket oocyte, however, the uptake of thymidine by follicular cell cytoplasm was followed by the transfer of radioactive DNA into the ooplasm (Favard-Sereno and Durand, 1963b).…”

“…Most evidence indicates that H 3 -thymidine is not incorporated into the germinal vesicle of the mature oocyte (Ficq, 1961a;Favard-Sereno and Durand, 1963b;Ficq, Aiello and Scarano, 1963) although recently Holland and Giese (1965) report that both the oogonia and the pre-leptotene primary oocytes of the sea urchin synthesize DNA within the ovary. These results imply that the synthesis of DNA needed for subsequent growth and maturation of the oocytes must occur after the last oogonial division and no later than the early premeiotic changes in the oocyte nucleus.…”

“…In contrast, the uptake of RNA precursors into the maturing oocyte appears to be widespread during oogenesis. In the starfish, H 3 -uridine uptake is localized in the nucleus, nucleolus (Ficq, 1961b) and cytoplasm (Geuskens, 1963), in the nucleus and nucleolus of the sea urchin oocyte (Ficq, Aiello and Scarano, 1963) and the nuclear sap, chromosomes and cytoplasm of the cricket oocyte (Favard-Sereno and Durand, 1963a). The use of H 3 -uridine and other precursors in conjunction with various inhibitors implicates the synthesis of at least three types of RNA (m-RNA, r-RNA and t-RNA) during maturation of the starfish and sea urchin oocyte (Ficq, 1961a;.…”