[The centriolar cycle in polykaryons formed in the fusion of heterophasic cells].
In this work we studied the centriolar cycle in fused cells containing heterophasic nuclei. Embryonic pig kidney cells were double-labeled with 3H- and 14C-thymidine and fused using a PEG-DMSO-serum method (Manandkhar et al., 1991). Fused cells containing nuclei at various cell cycle periods were selected after embedding in epon on the basis of isotope marking. Ultrastructure of centrioles was studied in serial ultrathin sections of selected cells. Centrioles of cells fused at different interphase periods showed a tendency to become synchronized in a manner similar to that of the nuclei. The G1-cell partners suppressed replication of S-centrioles or induced disorientation of centrioles of G2-diplosomes. In G1-S fused dikaryons, procentriole formation in G1-centrioles was not observed. This indicates the absence in the S-cell partner of an excess of a factor which could induce replication of the G1-centriole. However, G2-cell partner stimulated procentriole formation in G1- or unreplicated early S-centrioles. Asynchronous replication of G1-, S- and G2- centrioles was observed in some G1-S, G1-G2 and S-G2 fused cells. Heterophasic cellular environment containing mixed cell cycle factors appears to be responsible for the opposite effects on the structure of centrioles. In oocytes or early embryonic cells, due to the presence of a large amount of centriolar precursor material, centriolar replication cycle can proceed independently of the synthetic activity controlled by the nucleus.(ABSTRACT TRUNCATED AT 250 WORDS)
Manandkhar
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Onishchenko
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D000818:Animals; D002459:Cell Fusion; D002460:Cell Line; D002478:Cells, Cultured / Q000648:ultrastructure; D002502:Centrioles / Q000648:ultrastructure*; D004622:Embryo, Mammalian; D006822:Hybrid Cells / Q000648:ultrastructure*; D007399:Interphase; D008854:Microscopy, Electron; D016196:S Phase; D013552:Swine
Tsentrioliarnyĭ tsikl v polikarionakh, obrazuiushchikhsia pri sliianii geterofaznykh kletok.