[Chromatin structure and chromosomes on preparations of interphase nuclear derivatives after removal of nuclear envelopes. I. Method of preparation and morphology of residual nuclei in human leukocytes and intestinal epitheliocytes of Chironomus].
Demin SIu.AbstractA method of a stage by stage dismantling of the cell nucleus by a 0.5-5 min resuspending cells in physiological media containing 0.05 and 0.5% of non-ionic detergent Triton X-100 is first described. Depending on the detergent concentration and cell incubation time a suspension was obtained consisting of either practically undamaged nuclei with removed envelopes, cytoplasm-free mitotic figures and isolated envelopes gradually spreading interphase chromatin associated with nucleoplasm proteins. The article describes a technique to make from such a suspension preparations of spread and flattened derivatives of nucleus and mitotic chromosomes to use for optical microscopic research. This method allows to reveal perichromatin components of the nucleus and mitotic chromosome to study structure of chromonemic net and nucleoli of diploid nuclei of human leucocytes and non-polytenic nuclei of chironomus epitheliocytes and the discoidal structure of polynemic (low-polytenic) chromosomes from the midgut epithelium cells of chironomus larvae. An attempt was made to use the obtained preparations of flattened unenveloped nuclei in order to distinguish between human leucocytes according to the structure of their chromonemic net and silver-stained nucleolus, and to find out the manner of impregnation of argyrophilic nucleoplasm proteins. The partially isolated chironomus polynemic chromosomes have morphological manifestations of unproportional endoreduplication, local compactization of chromomers and physical association between a nucleolus and numerous of distant chromosome loci. We failed, however, to find any homology in the band pattern of such polynemic chromosomes and polytenic chromosomes of larval salivary gland cells. Individuality of chromosomes in polynemic nuclei was not so obvious due to a developed network of intra- and interchromosomal ectopic contacts. The discussion touches upon the mechanisms of isolation of nuclear envelopes and ways to restore the original shape of the unenveloped nucleus in the used hydrodynamic system with fading detergent activity. Prospects are mapped out to use this technique in the structural studies of interphase nuclei and mitotic and polynemic chromosomes.
Tsitologiia.Tsitologiia.1997;39(2-3):253-63.
A method of a stage by stage dismantling of the cell nucleus by a 0.5-5 min resuspending cells in physiological media containing 0.05 and 0.5% of non-ionic detergent Triton X-100 is first described. Depending on the detergent concentration and cell incubation time a suspension was obtained consistin
Chromosomal isolabelling caused by three rounds of synthesis in late replicating regions.
Wolff S, Bodycote J, Rodin B.AbstractIsolabelling only occurs in CHO cells that have been allowed to replicate for more than 2 but less than 3 cell divisions in the presence of BrdU. The isolabelling is confined to late replicating regions of the chromosomes. The staining patterns obtained indicate that BrdU was incorporated three times in these regions and that the isolabelling did not come from the segregation of label in polynemic chromosomes.
Chromosoma.Chromosoma.1978 Nov 22;69(2):179-83.
Isolabelling only occurs in CHO cells that have been allowed to replicate for more than 2 but less than 3 cell divisions in the presence of BrdU. The isolabelling is confined to late replicating regions of the chromosomes. The staining patterns obtained indicate that BrdU was incorporated three time
X-ray and UV-induced chromatid aberrations: evidence for polynemic chromosomes?
Bender MA, Bedford JS, Griggs HG, Merz T.AbstractIkushima and Wolff have recently interpreted both their observation of chromatid aberrations in second and third mitoses following X-irradiation and the production of chromatid type chromosomal aberrations by UV light administered during the G1 phase of the cell cycle in terms of a polyneme model of eukaryote chromosome structure. They were led to do so, however, largely because of their X-ray data, which the interpreted as evidence for the induction of sub-chromosomal lesions (by G1 irradiation; sub-chromatid for G2 irradiation) which appear as chromatid type aberrations only in later divisions. We here report data from similar X-ray experiments in which synchronized Chinese hamster tissue culture cells were irradiated in either G1 or G2 and then scored for chromatid aberrations in their first, second and third post-irradiation mitoses. Our results do not show the effect reported by Ikushima and Wolff. We conclude that all of the data available of aberration production is compatible with a simple mononeme model of eukaryote chromosome structure.
Mutation research.Mutat Res.1975 May;28(2):191-7.
Ikushima and Wolff have recently interpreted both their observation of chromatid aberrations in second and third mitoses following X-irradiation and the production of chromatid type chromosomal aberrations by UV light administered during the G1 phase of the cell cycle in terms of a polyneme model of
... structural parameters. This has not yet been achieved.Although emphasis in this review has been placed on uninemic and polynemic models, alternatives, such as a bineme, for example, remain. It is clear, moreover, that the 0 ...
These chromosomes sometimes become even larger than polynemic giant salivary gland chromosomes. The largest chromosome having a length upto 1 mm has been observed in urodele amphibian. The chromosomes seem to ...