Independence of Centriole Formation and Dna Synthesis

Abstract

The temporal relationship between cell cycle events and centriole duplication was investigated electron microscopically in L cells synchronized by mechanically selecting mitotic cells . The two mature centrioles which each cell received at telophase migrated together from the side of the telophase nucleus distal to the stem body around to a region of the cytoplasm near the stem body and then into a groovelike indention in the early Gl nucleus, where they were found throughout interphase . Procentrioles appeared in association with each mature centriole at times varying from 4 to 12 h after mitosis . Since S phase was found to begin on the average about 9 h after mitotic selection, it appeared that cells generated procentrioles late in Gt or early in S . During prophase, the two centriolar duplexes migrated to opposite sides of the nucleus and the daughter centrioles elongated to the mature length . To ascertain whether any aspect of centriolar duplication was contingent upon nuclear DNA synthesis, arabinosyl cytosine was added to mitotic cells at a concentration which inhibited cellular DNA synthesis by more than 99 % . Though cells were thus prevented from entering S phase, the course of procentriole formation was not detectibly affected . However, cells were inhibited from proceeding to the next mitosis, and the centriolar elongation and migration normally associated with prophase did not occur.

Centriole behavior in early mitosis of rat kangaroo cells (PTK2)

“…Such movement in P T K 2 cells is associated with an extensive array of microtubules which extend radially about the duplexes. These arrays, however, are less extensive than those associated with the duplexes in interphase (Rattner and Phillips, 1973). Therefore, the initiation of centriolar movement m a y correspond with a general reorganization of the cellular microtubular network.…”

The spindle pole body of Schizosaccharomyces pombe enters and leaves the nuclear envelope as the cell cycle proceeds.

“…In some cells, like budding yeast (Byers, 1981b) and cultured cell from vertebrates (Rattner and Phillips, 1973), centrosome duplication begins in late G1 or at about the onset of S phase. The single centrosome that was inherited at mitosis/cytokinesis serves as a site next to which a new centrosome assembles (Cleveland, 1963;Rieder and Borisy, 1982).…”

Centrioles in the cell cycle. I. Epithelial cells.

“…At the beginning of the G, period, during the G2 period, and in nonciliated cells in the Go period, one of the centrioles is situated perpendicular to the substrate. On the whole, it takes a mature centriole a cycle and a half to form in PE cells.The behavior of centrioles in the cell cycle has been described in a number of works (13,21,22,24,29,30), but the majority of authors have confined themselves to a description of some individual cycle phases rather than making a comprehensive analysis of all the periods of interphase and mitosis . The emphasis in these works is on the location of centrioles in the cell and on the time of their duplication, whereas the interaction between interphase centrioles and cytoplasmic microtubules and the dynamics of all centrosome structures are hardly mentioned .…”