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Ref ID : 491

Miss Raminder Chadha; Fine structure of the chromatin during the micronuclear mitotic cycle in Stylonychia mytilus Ehrenberg. Arch.Protistenk 123:406-421, 1980

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Fine structure of the chromatin during micronuclear mitotic cycle in the hypotrich Stylonychia mytilus has been studied using a synchronous population of cells. Four types of chromatin fibers of varying thickness have been observed. G1 micronucleus is characterized predominantly by the presence of type D fibers (0.12 um thick) and a fewer fibers of smaller thickness (type B- 8.28+/-0.25 nm and type A- 3.3+/-0.06 nm thick). During S phase, C type fibers about half the thickness of D type fibers make up the condensed chromatin zone of the micronucleus whereas diffused chromatin of the peripheral zone consists of type B fibers. Type B and C fibers are comparable to the chromatin fibers observed in the replication band of the macronucleus. Chromosomes in the division stages are made up of type B fibers only, which are more electron dense as compared to those in the interphase. It therefore appears that the organization of B type fibers is different at various stages of micronuclear mitotic cycle. The significance of these observations is discussed.