Effects of ultracentrifugation on the interphase nucleus of somatic cells with special reference to the nuclear envelope-chromatin relationship

1970 ◽  
Vol 108 (3) ◽  
pp. 297-308 ◽  
Author(s):  
H. W. Beams ◽  
Shirley Mueller
Keyword(s):  
Nuclear Envelope ◽  
Special Reference ◽  
Interphase Nucleus ◽  
Somatic Cells

scholarly journals PROPHASING OF INTERPHASE NUCLEI AND INDUCTION OF NUCLEAR ENVELOPES AROUND METAPHASE CHROMOSOMES IN HELA AND CHINESE HAMSTER HOMO- AND HETEROKARYONS

1974 ◽  
Vol 62 (1) ◽  
pp. 104-113 ◽  
Author(s):  
Yoshitaka Obara ◽  
Lee S. Chai ◽  
Herbert Weinfeld ◽  
Avery A. Sandberg
Keyword(s):  
Nuclear Envelope ◽  
Hela Cells ◽  
Interphase Nucleus ◽  
Chinese Hamster ◽  
Binucleate Cell ◽  
Metaphase Chromosomes ◽  
Interphase Nuclei ◽  
Multinucleate Cells ◽  
Interphase Cells ◽  
Nuclear Envelope Formation

Fusing human HeLa metaphase cells with HeLa interphase cells resulted within 30 min in either of two phenomena in the resultant binucleate cell: either prophasing of the interphase nucleus or formation of a normal-appearing nuclear envelope around the metaphase chromosomes. The frequency of either occurrence was strongly dependent on environmental pH. At pH's of 6.6–8.0, prophasing predominated; at pH 8.5 nuclear envelope formation predominated. Additionally, the frequencies of the two events in multinucleate cells depended on the metaphase/interphase ratio. When the ratio was 0.33 nuclear envelope formation predominated; when it was 2.0 prophasing predominated. In their general features, the results with fused HeLa cells resembled those reported earlier with fused Chinese hamster Don cells. However, the results provided an indication that between pH 6.6 and 8.0 the HeLa metaphase cells possessed a much greater capacity than the Don metaphase cells to induce prophasing. Fusion of Don metaphase cells with HeLa interphase cells or of Don interphase cells with HeLa metaphase cells at pH 8.0 resulted in nuclear envelope formation or prophasing in each kind of heterokaryon. As in the homokaryons, the frequencies of the two events in the heterokaryons depended on the metaphase/interphase ratio. The statistics of prophasing and nuclear envelope formation in the homo- and heterokaryon populations were consistent with the notion that disruption or formation of the nuclear envelope depends on the balance attained between disruptive and formative processes.

scholarly journals F-actin patches nucleated on chromosomes coordinate capture by microtubules in oocyte meiosis

2018 ◽  
Author(s):  
Mariia Burdyniuk ◽  
Andrea Callegari ◽  
Masashi Mori ◽  
François Nédélec ◽  
Péter Lénárt
Keyword(s):  
Nuclear Envelope ◽  
Somatic Cells ◽  
Oocyte Nucleus ◽  
Chromosome Loss ◽  
Dependent Manner ◽  
Actin Network ◽  
Nuclear Envelope Breakdown ◽  
Oocyte Meiosis ◽  
Spindle Microtubules ◽  
Ran Gtp

AbstractCapture of each and every chromosome by spindle microtubules is essential to prevent chromosome loss and aneuploidy. In somatic cells, astral microtubules search and capture chromosomes forming lateral attachments to kinetochores. However, this mechanism alone is insufficient in large oocytes. We have previously shown that a contractile F-actin network is additionally required to collect chromosomes scattered in the 70-μm starfish oocyte nucleus. How this F-actin-driven mechanism is coordinated with microtubule capture remained unknown. Here, we show that after nuclear envelope breakdown Arp2/3-nucleated F-actin patches form around chromosomes in a Ran-GTP-dependent manner, and we propose that these structures sterically block kinetochore-microtubule attachments. Once F-actin-driven chromosome transport is complete, coordinated disassembly of these F-actin patches allows synchronous capture by microtubules. Our observations indicate that this coordination is necessary, as early capture of chromosomes by microtubules would interfere with F-actin-driven transport leading to chromosome loss and formation of aneuploid eggs.

In situ arrangement of nor-bearing chromosomes in the interphase nucleus of Aotus trivirgatus

1984 ◽  
Vol 69 (1) ◽  
pp. 107-115
Author(s):  
C.A. Bourgeois ◽  
D. Costagliola ◽  
F. Laquerriere ◽  
F. Bard ◽  
D. Hemon ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Interphase Nucleus ◽  
Spatial Organization ◽  
Chromosome Arrangement ◽  
Diploid Complement ◽  
Nucleolus Organizing Region ◽  
Simulation Results ◽  
Experimental Values

The spatial organization of the two nucleolus-organizing region (NOR)-bearing chromosomes during interphase was studied in Aotus trivirgatus fibroblasts, using nucleoli as ultrastructural markers. Their distribution was examined by measuring the distances between them in 30 reconstructed nuclei, and comparing these experimental values with the theoretical ones obtained by simulation. Results were as follows: (1) the nucleoli are arranged in a polarized manner inside the nucleus; (2) the nucleoli are tightly bound to the nuclear envelope at two opposites sites; (3) the distance between the two nucleoli is variable, and is shorter than it would be if the two nucleoli were distributed at random. These findings indicate that the NOR-bearing chromosomes are fixed at the nuclear envelope in two opposite areas. They are also consistent with the hypothesis that each chromosome occupies a separate domain inside the nucleus. They can be interpreted according to the model in which chromosome arrangement within the interphase nucleus is based on the separation of the diploid complement into two independent haploid sets.

scholarly journals Ultrastructure of mitosis in the cowpea rust fungus Uromyces phaseoli var. Vignae.

1976 ◽  
Vol 70 (3) ◽  
pp. 592-607 ◽  
Author(s):  
I B Heath ◽  
M C Heath
Keyword(s):  
Nuclear Envelope ◽  
Interphase Nucleus ◽  
Rust Fungus ◽  
Metaphase Plate ◽  
Metaphase Chromosomes ◽  
Central Bundle ◽  
Late Telophase ◽  
Uromyces Phaseoli ◽  
Cytoplasmic Microtubules

Aspects of the ultrastructure of mitotic nuclei of the fungus Uromyces phaseoli var. vignae are described from both intercellular hyphae in the cowpea host and infection structures induced to differentiate in vitro. The interphase nucleus-associated organelle (NAO) consists of two trilamellar acircular disks connceted by an osmiophilic bar. The intranuclear spindle develops between these disks when they separate. The spindle contains pole to pole, interdigitating, chromosomal, and fragmentary microtubules arranged to form a central bundle along the surface of which lie the metaphase chromosomes. No metaphase plate is found. There are up to three microtubules per kinetochore and approximately 14 chromosomes on the haploid spindle. Telophase elongation appears to involve extension of pole to pole microtubules with no evidence for the remaining presence of interdigitating microtubules. Concomitantly, numerous cytoplasmic microtubules develop from each NAO disk where few or none are present in other phases. Reformation of the interphase NAO involves the formation of a sausage-shaped intermediate at late telophase. The nuclear envelope remains intact and the nucleolus persists throughtout division. Various aspects of the spindle and NAOs appear to be evolutionary intermediates between Ascomycetes and higher Basidiomycetes, thus supporting the theory of Basidiomycete evolution from the former group and demonstrating an encouraging correlation between mitotic characteristics and other phylogenetic markers.

Decondensation of the mouse sperm nucleus within the interphase nucleus

Zygote ◽  
1998 ◽  
Vol 6 (1) ◽  
pp. 39-45 ◽  
Author(s):  
Yasutaka Maeda ◽  
Hiroko Yanagimachi ◽  
Hiroyuki Tateno ◽  
Noriko Usui ◽  
R. Yanagimachi
Keyword(s):  
Nuclear Envelope ◽  
Interphase Nucleus ◽  
Sperm Nucleus ◽  
Interphase Nuclei ◽  
Mouse Sperm ◽  
Immature Oocytes ◽  
Nuclear Envelope Breakdown ◽  
Germinal Vesicles ◽  
Sperm Nuclei ◽  
Mouse Eggs

SummarySperm nuclei incorporated into the cytoplasm (ooplasm) of fertilised mouse eggs at the pronuclear stage remain condensed, whereas those injected into male or female pronuclei decondense. Similarly, sperm nuclei injected into germinal vesicles of immature oocytes or the nuclei of 2-cell embryos decondense, while those entering the cytoplasm of these oocytes / embryos do not. These facts seem to suggest that factors necessary for the decondensation of sperm nucleus are present in interphase nuclei and are released into the ooplasm during nuclear envelope breakdown. Nucleoplasmin, which is synthesised in the cytoplasm and accumulated within the nucleus, is likely a major candidate for these factors.

scholarly journals 23REPROGRAMMING MAMMALIAN CELLS IN XENOPUS EGG EXTRACTS: ROLE OF EMBRYONIC LAMIN B3

2004 ◽  
Vol 16 (2) ◽  
pp. 134
Author(s):  
R. Alberio ◽  
K.H.S. Campbell
Keyword(s):  
Dna Replication ◽  
Nuclear Envelope ◽  
Somatic Cells ◽  
Nuclear Transplantation ◽  
Heterologous System ◽  
Fetal Fibroblasts ◽  
Egg Extracts ◽  
Xenopus Egg ◽  
Xenopus Egg Extracts

The generation of animals by nuclear transplantation has demonstrated that a fully differentiated cell can be reversed into totipotency when transferred into an oocyte. Identification of oocyte specific molecules responsible for the reprogramming of somatic cells may contribute to the understanding of cell differentiation and embryo development. We have developed a heterologous system to investigate the effect of lamin B3, a major component of Xenopus laevis egg cytoplasm, on DNA replication of mammalian somatic cells. Bovine fetal fibroblasts were arrested at G1/S by incubation in aphidicolin for 18h. After permeabilization with digitonin, the cells were incubated in either (1) lamin B3 depleted, or (2) whole Xenopus egg extracts (1000 cells μL−1 extract) supplemented with an energy regenerating system for a period of 3h at 21°C. Xenopus lamin B3-depleted egg extracts were prepared by three rounds of incubation with Dynabeads coated with a mouse monoclonal lamin B3 antibody (mAbLB3). Immunodepletion was confirmed by western blotting. Purified lamin B3 was obtained by dialysis of the beads after immunodepletion, and the purified lamin B3 was used for rescue experiments. DNA replication of cells incubated in the extracts was assessed by adding 25μM Biotin-11-dUTP for 3h. After treatment cells were fixed in 70% methanol at −20°C and incubated in mAbLB3 for 30min at 37°C. This was followed by incubation in FITC-conjugated sheep anti-mouse antibody and in 5mgmL−1 Texas Red-conjugated Streptavidin for 40min at 37°C. After three hours’ incubation in egg extracts, DNA replication was detected in 60% of cells and more than 95% of cells were lamin B3 positive. In contrast, DNA replication in immunodepleted extracts was significantly lower (P≤0.01, by one-way ANOVA) than in cells incubated in whole extracts and was coincident with the few lamin B3-positive cells observed. More than 95% of cells were lamin B3-negative and did not replicate DNA. When purified lamin B3 was re-added to depleted extracts, DNA replication was detected in 60% of cells. DNA synthesis resumed in 93% of control cells 3h after release from aphidicolin into culture medium at 39°C. These experiments show that somatic nuclei, which possess a nuclear envelope with somatic variants of lamins, are able to synthesize DNA in egg extracts only when Xenopus lamin B3 is incorporated into the nuclear envelope. This heterologous system provides new information on the role of an embryonic molecule, namely Xenopus lamin B3, in the reprogramming of DNA replication of somatic cells incubated in egg environment. These results open new questions as to whether embryonic lamins also exist in mammals, and whether failure in development of cloned animals is in part due to abnormal or incomplete replacement of somatic variants of proteins with their embryonic counterparts.

Spatial Structure of Cytoplasmic Actin Filaments with Special Reference to the Association with Nuclear Envelope.

2012 ◽  
Vol 18 (S2) ◽  
pp. 62-63
Author(s):  
J. Uskura ◽  
S. Minakata
Keyword(s):  
Spatial Structure ◽  
Nuclear Envelope ◽  
Special Reference ◽  
Actin Filaments ◽  
Cytoplasmic Actin

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.

scholarly journals Anaphase onset in vertebrate somatic cells is controlled by a checkpoint that monitors sister kinetochore attachment to the spindle.

1994 ◽  
Vol 127 (5) ◽  
pp. 1301-1310 ◽  
Author(s):  
C L Rieder ◽  
A Schultz ◽  
R Cole ◽  
G Sluder
Keyword(s):  
Nuclear Envelope ◽  
Somatic Cells ◽  
Checkpoint Control ◽  
Average Interval ◽  
Nuclear Envelope Breakdown ◽  
Anaphase Onset ◽  
Sister Kinetochore ◽  
Chromosome Motion

To test the popular but unproven assumption that the metaphase-anaphase transition in vertebrate somatic cells is subject to a checkpoint that monitors chromosome (i.e., kinetochore) attachment to the spindle, we filmed mitosis in 126 PtK1 cells. We found that the time from nuclear envelope breakdown to anaphase onset is linearly related (r2 = 0.85) to the duration the cell has unattached kinetochores, and that even a single unattached kinetochore delays anaphase onset. We also found that anaphase is initiated at a relatively constant 23-min average interval after the last kinetochore attaches, regardless of how long the cell possessed unattached kinetochores. From these results we conclude that vertebrate somatic cells possess a metaphase-anaphase checkpoint control that monitors sister kinetochore attachment to the spindle. We also found that some cells treated with 0.3-0.75 nM Taxol, after the last kinetochore attached to the spindle, entered anaphase and completed normal poleward chromosome motion (anaphase A) up to 3 h after the treatment--well beyond the 9-48-min range exhibited by untreated cells. The fact that spindle bipolarity and the metaphase alignment of kinetochores are maintained in these cells, and that the chromosomes move poleward during anaphase, suggests that the checkpoint monitors more than just the attachment of microtubules at sister kinetochores or the metaphase alignment of chromosomes. Our data are most consistent with the hypothesis that the checkpoint monitors an increase in tension between kinetochores and their associated microtubules as biorientation occurs.

scholarly journals STRUCTURE IN NUCLEATED ERYTHROCYTES

1961 ◽  
Vol 9 (3) ◽  
pp. 671-687 ◽  
Author(s):  
Howard G. Davies
Keyword(s):  
Electron Microscopy ◽  
Nuclear Envelope ◽  
Light Microscope ◽  
Phase Contrast ◽  
Somatic Cells ◽  
Chemical Substance ◽  
Feulgen Staining ◽  
Nuclear Pores ◽  
Specific Absorption ◽  
Static Pictures

The structure of the nucleated erythrocyte of frog and chicken has been investigated by electron microscopy and correlated with the distribution of haemoglobin and DNA-containing material determined by haem absorption and Feulgen staining in the light microscope. The nuclei of both species are found to contain haemoglobin which is continuous with the haemoglobin in the cytoplasm through holes or pores in the nuclear envelope. In addition the nucleus of the frog erythrocyte sometimes contains a single invagination which is lined by the nuclear envelope. The structure of the nuclear envelope and the pores and the organisation of the nucleus are similar to those already described for other somatic cells. Erythrocytes differ from the cells previously studied in that a continuity, via the nuclear pores, of chemical substance in the interior of the nucleus and in the cytoplasm can be directly demonstrated. This is due to the fact that the cytoplasm of erythrocytes is simple, consisting predominantly of haemoglobin, and that haemoglobin is easily recognised by its specific absorption. The static pictures obtained by electron microscopy have been supplemented by observations in phase-contrast of the changes in refraction of the cell contents due to the diffusion of the haemoglobin from the nucleus into the cytoplasm during haemolysis.

Sign in / Sign up

Export Citation Format

Share Document