[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].

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 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.