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At least 19 recordsLinked to original sources
PubMed1976

Laser UV microirradiation of interphase nuclei and post-treatment with caffeine. A new approach to establish the arrangement of interphase chromosomes.

Laser UV microirradiation of Chinese hamster interphase cells combined with caffeine post-treatment produced different patterns of chromosome damage in mitosis following irradiation of a small area of the nucleus that may be classified in three categories: I)intact metaphase figures, II)chromosome damage confined to a small area of the metaphase spread, III)mitotic figures with damage on all chromosomes. Category III might be the consequence of a non-localized distortion of nuclear metabolism. By contrast, category II may reflect localized DNA damage induced by microirradiation, which could not be efficiently repaired due to the effect of caffeine. If this interpretation is right, in metaphase figures of category II chromosome damage should occur only at the irradiation site. The effect might then be used to investigate neighbourhood relationships of individual chromosomes in the interphase nucleus.

Animals↗
PubMed1992

Relationship between interphase AgNOR distribution and nucleolar size in cancer cells.

We have studied the relationship between interphase nucleolar organizer region (NOR) distribution and nucleolar size in cancer cells at light-microscopical level. Thirteen cases of formalin-fixed bladder cancer and fifteen cases of methacarn-fixed tumours of different origin were used. Nucleoli of the former cases were stained by Phloxine B and of the latter by Toluidine Blue. Selective visualization of interphase NORs was obtained by carrying out the one-step silver staining reaction for AgNOR proteins (Ploton et al., 1986). The area occupied by Phloxine B- or Toluidine Blue-stained nucleoli and interphase silver-stained NORs was measured by means of an automated image analyser. Both in bladder cancers and in the other tumour lesions nucleolar and interphase AgNOR areas were linearly related (r = 0.95 and r = 0.96, respectively, P < 0.001). The close relationship between the area of nucleoli and that of silver-stained nucleolar structures was maintained even if the silver-staining procedure was prolonged beyond the optimal time length for selective interphase NOR staining. In the latter case, however, single interphase AgNORs were no longer visible within the nucleolar body which was, in fact, homogeneously stained. These data indicate that evaluation of the interphase AgNOR area has the same relevance, in tumour pathology, as whole nucleolar size measurement.

Cell Nucleolus↗
PubMed1979

Visualization of the interphase chromosomes of Ornithogalum virens and Muntiacus muntjak.

A technique for visualizing "interphase chromosomes" was applied to nuclei of the angio-spermous plant, Ornithogalum virens (2 n = 6), and the male mammal, Muntiacus munjak (2 n = 7), in an attempt to correlate the numbers of "chromosomes" visible during interphase with the respective diploid chromosome numbers. The alterations in chromosome structure observed during G1, S, and G2 periods were comparable to those previously reported in Allium cepa and Chinese hamster (CHO line) cells [33], but for technical reasons it was only possible to make accurate counts of interphase chromosomes in the G1 nuclei of O. virens. In addition, from our observations of interphase chromosomes that were pulse-labelled with tritiated thymidine and a parallel study of premature chromosome condensation (PCC) using pulse-labelled M.muntjak cells, we conclude that, although chromatin decondensation may be required for DNA synthesis, extreme chromatin decondensation can occur in the absence of DNA synthesis. Generally a morphological description of alterations in chromatin during interphase only roughly parallels the G1, S, and G2 phases defined by autoradiography following incorporation of tritiated thymidine. We suggest that both methods are valid through different ways of describing interphase.

Animals↗
PubMed1977

Different sensitivity of DNA in situ in interphase and metaphase chromatin to heat denaturation.

Heat denaturation of DNA in situ, in unbroken cells, was studied in relation to the cell cycle. DNA in metaphase cells denatured at lower temperatures (8 degrees-10 degrees C lower) than DNA in interphase cells. Among interphase cells, small differences between G1, S, and G2 cells were observed at temperatures above 90 degrees C. The difference between metaphase and interphase cells increased after short pretreatment with formaldehyde, decreased when cells were heated in the presence of 1 mM MgCl2, and was abolished by cell pretreatment with 0.5 N HCl. The results suggest that acid-soluble constituents of chromatin confer local stability to DNA and that the degree of stabilization is lower in metaphase chromosomes than in interphase nuclei. These in situ results remain in contrast to the published data showing no difference in DNA denaturation in chromatin isolated from interphase and metaphase cells. It is likely that factors exist which influence the stability of DNA in situ are associated with the super-structural organization of chromatin in intact nuclei and which are lost during chromatin isolation and solubilization. Since DNA denaturation is assayed after cell cooling, there is also a possibility that the extent of denatured DNA may be influenced by some factors that control strand separation and DNA reassociation. The different stainability of interphase vs. metaphase cells, based on the difference in stability of DNA, offers a method for determining mitotic indices by flow cytofluorometry, and a possible new parameter for sorting cells in metaphase.

Cell Division↗
PubMed1992

Effects of cryopreservation on survival and development of interphase- and mitotic-stage 1-cell mouse embryos.

The effects of cryopreservation with 1,2-propanediol on two groups of 1-cell mouse embryos were studied in terms of survival after thawing, growth in vitro until the blastocyst stage and development in vivo assessed by the number of implantations and living fetuses. The two groups were divided according to different stages in the cell cycle: cells in (i) interphase with two distinct pronuclei or (ii) mitosis just prior to the first cleavage division. Zygotes in the interphase stage proved to be more resistant to freezing and thawing procedures, showing a significantly higher survival rate after thawing than zygotes in mitosis (78.5 versus 61.3%, P < 0.05). Blastocyst formation was similar in the two experimental groups: 72.7% for interphase and 60.8% for mitosis (P = 0.06), but for both groups fewer blastocysts formed when compared with the control group (86.7%) (P < or = 0.01). The implantation rates were not statistically different: 54.2% for the interphase cells and 47.4% for the control group and 44.0% for the mitotic cells and 49.4% for the control group. The formation of living fetuses was similar between the experimental and control groups: 36.5% for the interphase group (40.0% for its control group) and 22.6% for the mitotic group (38.8% for its control group). We conclude that freezing embryos during nuclear division is detrimental for their survival after thawing.

Animals↗
PubMed1975

Interphase chromosome arrangement in Anopheles atroparvus.

The arrangement of chromosomes in interphase nuclei of Anopheles atroparvus has been inferred from an analysis of: 1. The early stages of mitosis as seen following Quinacrine staining, and 2. The reversible effects on the chromatin pattern obtained following the treatment of living cells with various NaCl solutions, and the following conclusions have been reached: (a) The chromatin is connected to the nuclear membrane, (b) Homologous chromosomes show close side-by-side somatic pairing, (c) The long arms of the sex chromosomes form a fluorescent peripheral body, (d) The autosomes are strongly reflexed at the centromeres, (e) The autosomal centromeric regions are polarized towards the peripheral body, (f) The telomeric regions of all the autosomes are closely apposed.--A ring-shaped pattern of interphase chromatin is constantly and reversibly induced by NaCl 0.15 to 0.18 M solutions.--These relationships indicate a peripheral arrangement of the interphase somatic complement.--The distribution of the chromosomes in polytene nuclei and at the beginning of meiosis resembles that suggested above for somatic interphase cells. This distribution may apply more widely in the Diptera.

Animals↗
PubMed2026

Live dynamics of induced cell-cell fusion between mitotic and interphasic cells.

The cell cycle is tightly regulated by checkpoint mechanisms that ensure faithful duplication and segregation of the genome. Here, we induced cell-cell fusion between mitotic and interphase cells to study how nuclei from different cell cycle stages behave in a shared cytoplasm. We found that mitosis is a dominant cell cycle state: the mitotic cytoplasm can drive interphase nuclei into mitosis, whereas, in high ratios of interphase versus mitotic nuclei, fusion forced mitotic nuclei to exit mitosis. Both outcomes represent checkpoint override events with impactful consequences. Interphase nuclei forced into mitosis form aberrant mitotic spindles, show partially condensed DNA and ultimately undergo mitotic catastrophe. Conversely, forced mitotic exit resulted in reformation of nuclear envelope membranes around condensed chromosomes, forming nuclei with a defective nuclear import machinery. Altogether, cell-cell fusion revealed the consequences of checkpoint override, forcing nuclei through untimely cell cycle transitions, and highlight how cell-cell fusion experiments can be a powerful system to study how competing cytoplasmic states are integrated in a shared cytoplasm, such as in muscle, placenta formation and in cancer.

Cell cycle↗
PubMed1977

Orientation of interphase chromosomes as detected by Giemsa C-bands.

The orientation of Giemsa C-bands has been studied in mitotic and interphase cells of Allium cepa. A sativum and of Aloe vera. The C-bands in these three species are located at the telomeres, secondary constriction region of the nucleolar chromosomes and the centromeric regions, respectively. Observations in A. cepa and Aloe indicate clearly that the interphase chromosomes are non-random in their orientation and possibly maintain their telophase configuration through the attachment of telomeres and perhaps of kinetochores with the nuclear membrane. Electron micrographs of onion cells also reveal that certain heterochromatic segments are associated with the nuclear membrane.--The nucleolar interstitial C-bands in A. sativum remain free in the nucleoplasm and may come close to each other due to heterochromatic attraction. Such a heterochromatic attraction is also evident between telomeric regions and between centromeres. However, a two by two attachment could not be noticed. A diagrammatic representation of the orientation of interphase chromosomes has been presented.

Azure Stains↗
PubMed1979

The similarity of DNA sequences remaining bound to scaffold upon nuclease treatment of interphase nuclei and metaphase chromosomes.

The fragments of DNA attached to protein skeleton of interphase nuclei or metaphase chromosomes were obtained. Both the method involving restriction endonuclease treatment/1,2/and a novel procedure based on mild staphylococcal nuclease digestion were used. In the latter case, DNA fragments remaining bound to nuclei or chromosomes are not enriched in satellite but only in abundant middle repetitive DNA. The shorter the fragments of attached DNA, the higher the content of middle repetitive DNA in the fraction. It has a slightly higher density in a CsCl gradient comparing to the main DNA. The yield of attached DNA, its distribution in a CsCl density gradient, and its renaturation properties are essentially the same for interphase and metaphase chromosomes. The average size of DNA loops was found to be equal to approximately 60 kb for both metaphase chromosomes and interphase nuclei. The conclusion has been drawn that the bulk of attachment sites of DNP fibrils to axial chromosomal structures remains unchanged during the cell cycle.

Animals↗
PubMedDate not supplied

[Rheological studies of interphase adsorption layers of lysozyme at phase separation liquid boundaries].

Rheological studies of thin layers of biopolymers provide a principally new approach to the studies of the structure and functions of biomembranes. Rheological properties of interphase adsorption layers of lysozyme at different concentrations, temperatures and at the border with various carbohydrates. The values of moduli of fast elastic deformation E1s, slow elastic deformation E2s, equilibrium module of elasticity Es, viscosity of elastic aftereffect, plastic viscosity eta 0s and eta s for the interphase layers of lysozyme at liquid borders show that the interphase adsorption layers were solidlike, and the moduli of dimeric structure evaluated as volume ones correspond to the characteristics of normal elastomeres.

Adsorption↗
PubMed1976

[C- and Q-chromatin of the experimentally condensed human interphase chromosomes].

Condensed interphase chromosomes of the cultured human lymphocytes obtained by the fusion of interphase and metaphase cells were studied using C- and Q-bands techniques. The appearance and localization of the constitutive heterochromatin blocks on condensed chromosomes at G1-period were the same as on the metaphase ones. These characters were used for a group and individual identification of some chromosomes condensed at G1-period and for a study of the association of the constitutive heterochromatin blocks in the interphase nuclei. The fluorescent analysis of the chromosomes condensed at G1-period detected some bright fluorescent blocks of the constitutive heterochromatin.

Cell Division↗
PubMed1979

The grasshopper X chromosome. I. States of condensation and the nuclear envelope at G1, S and G2 of premeiotic interphase and at early meiotic prophase.

The sub-stages of spermatocyte interphase (G1, S and G2) have been identified in the grasshopper Brachystola magna using E.M. autoradiography and serial thin sectioning techniques. The X chromosome occupies a nuclear envelope bound compartment separate from an autosome compartment during G1 and S. At G2 the X compartment is resolved by coalescence of the membranes enveloping the X chromosome and autosome compartments.--At G1 and S, the compartmentalized X chromatin is laced with nuclear membrane material. This X chromatin associated membrane decreases in amount as the cell passes through G2 and enters early meiotic prophase. There are at least 2 and possibly 3 states of condensation of the heterochromatic X during premeiotic interphase and early meiotic prophase correlated with the presence or absence of membrane material associated with the chromatin.--The X chromatin replicates asynchronously with autosomal euchromatin and synchronously with autosomal heterochromatin associated with nucleoli. The X chromatin replication appears to be associated with the nuclear membrane.--The observations indicate that the nuclear membrane is involved with X chromosome condensation and may be implicated in asynchronous X chromosome replication as well.

Animals↗
PubMed1978

Number of nucleoli in Ehrlich tumor cells during interphase.

Fractions of mouse Ehrlich ascites tumor cell populations with a high percentage of cell either in early or in late interphase were separated by centrifugation on ficoll gradients. Nucleoli were studied by light or electron microscopy in these cell subpopulations. It was shown that, in these cells, the number of nucleoli per nucleus does not vary significantly during interphase. This result is discussed and an anlysis of the relationships between the number and the volume of the nucleoli in these cells is present.

Animals↗
PubMed1978

Structure of interphase nuclei in relation to the cell cycle. Chromatin organization in mouse L cells temperature-sensitive for DNA replication.

Mutant lines of mouse L cells, TS A1S9, and TS C1, show temperature-sensitive (TS) DNA synthesis and cell division when shifted from 34 degrees to 38.5 degrees C. With TS A1S9 the decline in DNA synthesis begins after 6-8 h at 38.5 degrees C and is most marked at about 24 h. Most cells in S, G2, or M at temperature upshift complete one mitosis and accumulate in the subsequent interphase at G1 or early S as a result of expression of a primary defect, failure of elongation of newly made small DNA fragments. Heat inactivation of TS C1 cells is more rapid; they fail to complete the interphase in progress at temperature upshift and accumulate at late S or G2. Inhibition of both cell types is reversible on return to 34 degrees C. Cell and nuclear growth continues during inhibition of replication. Expression of both TS mutations leads to a marked change in gross organization of chromatin as revealed by electron microscopy. Nuclei of wild-type cells at 34 degrees and 38.5 degrees C and mutant cells at 34 degrees C show a range of aggregation of condensed chromatin from small dispersed bodies to large discrete clumps, with the majority in an intermediate state. In TS cells at 38.5 degrees C, condensed chromatin bodies in the central nuclear region become disaggregated into small clumps dispersed through the nucleus. Morphometric estimation of volume of condensed chromatin indicates that this process is not due to complete decondensation of chromatin fibrils, but rather involves dispersal of large condensed chromatin bodies into finer aggregates and loosening of fibrils within the aggregates. The dispersed condition is reversed in nuclei which resume DNA synthesis when TS cells are downshifted from 38.5 degrees to 34 degrees C. The morphological observations are consistent with the hypothesis that condensed chromatin normally undergoes an ordered cycle of transient, localized disaggregation and reaggregation associated with replication. In temperature-inactivated mutants, normal progressive disaggregation presumably occurs, but subsequent lack of chromatin replication prevents reaggregation.

Cell Count↗
PubMed1978

Immunocytochemical localization of the major polypeptides of the nuclear pore complex-lamina fraction. Interphase and mitotic distribution.

This laboratory has previously isolated a fraction from rat liver nuclei consisting of nuclear pore complexes associated with the proteinaceous lamina which underlies the inner nuclear membrane. Using protein eluted from sodium dodecyl sulfate (SDS) gels, we have prepared antibodies in chickens to each of the three predominant pore complex-lamina bands. Ouchterlony double diffusion analysis shows that each of these individual bands cross-reacts strongly with all three antisera. In immunofluorescence localization performed on tissue culture cells with these antibodies, we obtain a pattern of intense staining at the periphery of the interphase nucleus, with little or no cytoplasmic reaction. Electron microscope immunoperoxidase staining of rat liver nuclei with these antibodies labels exclusively the nuclear periphery. Furthermore, reaction occurs in areas which contain the lamina, but not at the pore complexes. While our isolation procedure extracts the internal contents of nuclei completely, semiquantitative Ouchterlony analysis shows that it releases negligible amounts of these lamina antigens. Considered together, our results indicate that these three bands represent major components of a peripheral nuclear lamina, and are not structural elements of an internal "nuclear protein matrix." Fluorescence microscopy shows that the perinuclear interphase localization of these lamina proteins undergoes dramatic changes during mitosis. Concomitant with nuclear envelope disassembly in prophase, these antigens assume a diffuse localization throughout the cell. This distribution persists until telophase, when the antigens become progressively and completely localized at the surface of the daughter chromosome masses. We propose that the lamina is a biological polymer which can undergo reversible disassembly during mitosis.

Cell Cycle↗
PubMed1978

The nature of the Ag-staining of nucleolus organizer regions. Electron- and light-microscopic studies on human cells in interphase, mitosis, and meiosis.

Electron micrographs reveal that the Ag-stainable substance is located on the outside of NOR's or around them but not in the chromosomes themselves. In association figures, the Ag-positive material lies between the acrocentric chromosomes. Light-microscopic studies show that the Ag stainability of the nucleolus in interphase is correlated with the function of the NOR, as seen from inactive and activated lymphocytes. Much more Ag-positive material is seen in prophase than in meta- and anaphase. It starts to increase again in late telophase. In male meiosis the NOR's remain Ag-positive until pachytene. First and second metaphase figures are negative. Experiments using RNase, TCA, and trypsin indicate that the Ag-stainable substance is an acidic protein. The precipitation of Ag granules in interphase nuclei seen in the electron microscope is greatest over the fibrillar component of the nucleolus. The most likely interpretation is that the Ag-stainable material is a component of ribonucleic protein accumulating around active NOR's. In mitosis some of this material remains at the NOR's. In first meiosis it is completely removed before diakinesis.

Animals↗