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Journal articles on the topic 'Nucleu'
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1
Vasilescu, Gabriel Dragos, Emilian Ghicioi, Sorin Simion, and Vlad Pasculescu. "Model for Forecasting the Exposure Risk of Workers to Hand-Arm Occupational Vibrations." Applied Mechanics and Materials 430 (September 2013): 276–80. http://dx.doi.org/10.4028/www.scientific.net/amm.430.276.
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This paper work presents the model for forecasting the exposure risk of workers to hand-arm occupational vibrations, which has been achieved in the PN 07 45 01 18 Project from within the framework of the NUCLEU/2012-2013 Program.This project is of national and European interest, in order to increase occupational health and safety level and to ensure sustainable environmental quality and comfort at work.
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Drumea, Petrin, Corneliu Cristescu, Catalin Dumitrescu, Iulian Dutu, and Ioana Ilie. "Research Regarding the Dynamic Behavior of Linear Hydraulic Servo-Systems." Applied Mechanics and Materials 325-326 (June 2013): 480–85. http://dx.doi.org/10.4028/www.scientific.net/amm.325-326.480.
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The paper presents the theoretical results of extensive research on the dynamic behavior of linear hydraulic motors, carried out in INOE 2000-IHP, in the framework of the NUCLEU Programmer. The research has been conducted both theoretically and experimentally, but, in this paper, is presented only the theoretical research. Theoretical research has taken place with the modern means of mathematical modeling and computer numerical simulation. The article presents some theoretical interested results obtained in the research, results that are of real scientific interest, but, also, with practical value through their use in the design of fluid power components and equipments.
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Barlas, Orhan, Ha?met A. Hana?as?, Murat ?mer, H�seyin A. ?ahin, Serra Sencer, and Murat Emre. "Do unilateral ablative lesions of the subthalamic nucleu in parkinsonian patients lead to hemiballism?" Movement Disorders 16, no. 2 (2001): 306–10. http://dx.doi.org/10.1002/mds.1051.
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Dimitrova, D. S., and D. M. Gilbert. "Regulation of mammalian replication origin usage in Xenopus egg extract." Journal of Cell Science 111, no. 19 (October 1, 1998): 2989–98. http://dx.doi.org/10.1242/jcs.111.19.2989.
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Xenopus embryos initiate replication at random closely spaced sites until a certain concentration of nuclei is achieved within the embryo, after which fewer, more specific chromosomal sites are utilized as origins. We have examined the relationship between nucleo-cytosolic ratio and origin specification when Chinese hamster ovary (CHO) cell nuclei are introduced into Xenopus egg extracts. At concentrations of intact late-G1-phase nuclei that approximate early Xenopus embryos, the entire genome was duplicated nearly 4 times faster than in culture, accompanied by a de-localization of initiation sites at the dihydrofolate reductase (DHFR) locus. As the concentration of nuclei was increased, the number of initiation sites per nucleus decreased and initiation at the DHFR locus became localized to the physiologically utilized DHFR origin. Origin specification was optimal at nuclear concentrations that approximate the Xenopus mid-blastula transition (MBT). Higher concentrations resulted in an overall inhibition of DNA synthesis. By contrast, with intact early G1-phase nuclei, replication initiated at apparently random sites at all concentrations, despite an identical relationship between nucleo-cytosolic ratio and replicon size. Furthermore, permeabilization of late-G1-phase nuclei, using newly defined conditions that preserve the overall rate of replication, eliminated site-specificity, even at nuclear concentrations optimal for DHFR origin recognition. These data show that both nucleo-cytosolic ratio and nuclear structure play important but independent roles in the regulation of replication origin usage. Nucleo-cytosolic ratio clearly influences the number of replication origins selected. However, titration of cytosolic factors is not sufficient to focus initiation to specific sites. An independent mechanism, effecting changes within G1-phase nuclei, dictates which of many potential initiation sites will function as an origin.
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Chan, Jonathan KL, Paul C. Park, and Umberto De Boni. "Association of DNAse sensitive chromatin domains with the nuclear periphery in 3T3 cells in vitro." Biochemistry and Cell Biology 78, no. 2 (April 1, 2000): 67–78. http://dx.doi.org/10.1139/o99-074.
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DNAse sensitive chromatin, putative transcriptionally competent sequences, exists either as pan-nuclear speckles in cells with nuclei which exhibit a flat geometry, or as a shell apposed to the nuclear envelope in cells with spheroidal nuclei. To test the hypothesis that DNAse sensitive chromatin is similarly associated with the nuclear periphery in cell types with a very flat geometry such as 3T3 fibroblasts, cells were subjected to hypotonic expansion to change their nuclei from a flat ellipsoid to a spheriod. This was based on the assumption that such a spatial association is not resolvable due to the interdigitation at the nuclear midplane of DNAse sensitive chromatin associated with the upper and lower nuclear surfaces. In situ nick translation was used to visualize the distribution of DNAse sensitive chromatin as a function of nuclear geometry. Both unexpanded and expanded cells exhibit DNAse sensitive chromatin as a dome at the apical side of the nucleus, i.e., that aspect of the cell facing the culture medium. The results argue for a polarized association of DNAse sensitive chromatin with the nuclear envelope and indicate that the nuclear periphery may function as a compartment for the spatial coupling of transcription and nucleo-cytoplasmic transport. Key words: nuclear organization, DNAse sensitive chromatin, hypotonic expansion, 3T3 cells.
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Leitch, Andrew R. "Higher Levels of Organization in the Interphase Nucleus of Cycling and Differentiated Cells." Microbiology and Molecular Biology Reviews 64, no. 1 (March 1, 2000): 138–52. http://dx.doi.org/10.1128/mmbr.64.1.138-152.2000.
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SUMMARY The review examines the structured organization of interphase nuclei using a range of examples from the plants, animals, and fungi. Nuclear organization is shown to be an important phenomenon in cell differentiation and development. The review commences by examining nuclei in dividing cells and shows that the organization patterns can be dynamic within the time frame of the cell cycle. When cells stop dividing, derived differentiated cells often show quite different nuclear organizations. The developmental fate of nuclei is divided into three categories. (i) The first includes nuclei that undergo one of several forms of polyploidy and can themselves change in structure during the course of development. Possible function roles of polyploidy is given. (ii) The second is nuclear reorganization without polyploidy, where nuclei reorganize their structure to form novel arrangements of proteins and chromosomes. (iii) The third is nuclear disintegration linked to programmed cell death. The role of the nucleus in this process is described. The review demonstrates that recent methods to probe nuclei for nucleic acids and proteins, as well as to examine their intranuclear distribution in vivo, has revealed much about nuclear structure. It is clear that nuclear organization can influence or be influenced by cell activity and development. However, the full functional role of many of the observed phenomena has still to be fully realized.
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Chisoi, Anca, Mariana Aşchie, and Manuela Enciu. "Morphometric Characterization of Marginal Zone Lymphoma." ARS Medica Tomitana 21, no. 1 (February 1, 2015): 17–21. http://dx.doi.org/10.1515/arsm-2015-0014.
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Abstract The morphometry in histopathology is used to characterize cell populations belonging to different tissues and to identify differences in their parameters with prognostic implications. To achieve morphometric examination were selected 6 of 8 cases identified as marginal zone lymphoma. For each case analysis was done on five fields, for each field measuring the parameters of 20 cells. The studied parameters were for cytoplasm: cytoplasmic area, maximum and minimum cytoplasmic diameter, cytoplasmic perimeter; for nucleus were measured: nuclear area, minimum and maximum nuclear diameter, nuclear perimeter, nuclear contour index, nuclear ellipticity index, nuclear irregularity index. Also the nucleo-cytoplasmic ratio was calculated in all studied cases. Marginal zone lymphoma is characterized in terms of morphometric parameters by small cytoplasmic and nuclear area, and small nucleo-cytoplasmatic ratio of about 1:1. Nuclear contour index is small, accompanied by a large ellipticity index and an small index of nuclear irregularity. Standard deviations for measured morphometric parameters are variable, having high values for cytoplasmic and nuclear area, highlighting the polymorphic nature of the cells. Morphometric aspects, with corresponding microscopic aspects of large and small lymphocyte proliferation with cleaved and uncleaved nuclei, fit this form of lymphoma in terms of clinical outcome in indolent lymphomas category.
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Foe, V. E., and B. M. Alberts. "Reversible chromosome condensation induced in Drosophila embryos by anoxia: visualization of interphase nuclear organization." Journal of Cell Biology 100, no. 5 (May 1, 1985): 1623–36. http://dx.doi.org/10.1083/jcb.100.5.1623.
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We have studied the morphology of nuclei in Drosophila embryos during the syncytial blastoderm stages. Nuclei in living embryos were viewed with differential interference-contrast optics; in addition, both isolated nuclei and fixed preparations of whole embryos were examined after staining with a DNA-specific fluorescent dye. We find that: (a) The nuclear volumes increase dramatically during interphase and then decrease during prophase of each nuclear cycle, with the magnitude of the nuclear volume increase being greatest for those cycles with the shortest interphase. (b) Oxygen deprivation of embryos produces a rapid developmental arrest that is reversible upon reaeration. During this arrest, interphase chromosomes condense against the nuclear envelope and the nuclear volumes increase dramatically. In these nuclei, individual chromosomes are clearly visible, and each condensed chromosome can be seen to adhere along its entire length to the inner surface of the swollen nuclear envelope, leaving the lumen of the nucleus devoid of DNA. (c) In each interphase nucleus the chromosomes are oriented in the "telophase configuration," with all centromeres and all telomeres at opposite poles of the nucleus; all nuclei at the embryo periphery (with the exception of the pole cell nuclei) are oriented with their centromeric poles pointing to the embryo exterior.
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Dundon, Samantha E. R., Shyr-Shea Chang, Abhishek Kumar, Patricia Occhipinti, Hari Shroff, Marcus Roper, and Amy S. Gladfelter. "Clustered nuclei maintain autonomy and nucleocytoplasmic ratio control in a syncytium." Molecular Biology of the Cell 27, no. 13 (July 2016): 2000–2007. http://dx.doi.org/10.1091/mbc.e16-02-0129.
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Nuclei in syncytia found in fungi, muscles, and tumors can behave independently despite cytoplasmic translation and the homogenizing potential of diffusion. We use a dynactin mutant strain of the multinucleate fungus Ashbya gossypii with highly clustered nuclei to assess the relative contributions of nucleus and cytoplasm to nuclear autonomy. Remarkably, clustered nuclei maintain cell cycle and transcriptional autonomy; therefore some sources of nuclear independence function even with minimal cytosol insulating nuclei. In both nuclear clusters and among evenly spaced nuclei, a nucleus’ transcriptional activity dictates local cytoplasmic contents, as assessed by the localization of several cyclin mRNAs. Thus nuclear activity is a central determinant of the local cytoplasm in syncytia. Of note, we found that the number of nuclei per unit cytoplasm was identical in the mutant to that in wild-type cells, despite clustered nuclei. This work demonstrates that nuclei maintain autonomy at a submicrometer scale and simultaneously maintain a normal nucleocytoplasmic ratio across a syncytium up to the centimeter scale.
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Walters, Alison D., Kwabena Amoateng, Renjie Wang, Jian-Hua Chen, Gerry McDermott, Carolyn A. Larabell, Olivier Gadal, and Orna Cohen-Fix. "Nuclear envelope expansion in budding yeast is independent of cell growth and does not determine nuclear volume." Molecular Biology of the Cell 30, no. 1 (January 2019): 131–45. http://dx.doi.org/10.1091/mbc.e18-04-0204.
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Most cells exhibit a constant ratio between nuclear and cell volume. The mechanism dictating this constant ratio and the nuclear component(s) that scale with cell size are not known. To address this, we examined the consequences to the size and shape of the budding yeast nucleus when cell expansion is inhibited by down-regulating components of the secretory pathway. We find that under conditions where cell size increase is restrained, the nucleus becomes bilobed, with the bulk of the DNA in one lobe and the nucleolus in the other. The formation of bilobed nuclei is dependent on fatty acid and phospholipid synthesis, suggesting that it is associated with nuclear membrane expansion. Bilobed nuclei appeared predominantly after spindle pole body separation, suggesting that nuclear envelope expansion follows cell-cycle cues rather than cell size. Importantly, cells with bilobed nuclei had the same nuclear:cell volume ratio as cells with round nuclei. Therefore, the bilobed nucleus could be a consequence of continued NE expansion as cells traverse the cell cycle without an accompanying increase in nuclear volume due to the inhibition of cell growth. Our data suggest that nuclear volume is not determined by nuclear envelope availability but by one or more nucleoplasmic factors.
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Soler, A. P., K. A. Thompson, R. M. Smith, and L. Jarett. "Immunological demonstration of the accumulation of insulin, but not insulin receptors, in nuclei of insulin-treated cells." Proceedings of the National Academy of Sciences 86, no. 17 (September 1989): 6640–44. http://dx.doi.org/10.1073/pnas.86.17.6640.
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Although insulin is known to regulate nuclear-related processes, such as cell growth and gene transcription, the mechanisms involved are poorly understood. Previous studies suggested that translocation of insulin or its receptor to cell nuclei might be involved in some of these processes. The present investigation demonstrated that intact insulin, but not the insulin receptor, accumulated in nuclei of insulin-treated cells. Cell fractionation studies demonstrated that the nuclear accumulation of 125I-labeled insulin was time-, temperature-, and insulin-concentration-dependent. Electron microscopic immunocytochemistry demonstrated that the insulin that accumulated in the nucleus was immunologically intact and associated with the heterochromatin. Only 1% of the 125I-labeled insulin extracted from isolated nuclei was eluted from a Sephadex G-50 column as 125I-labeled tyrosine. Plasma membrane insulin receptors were not detected in the nucleus by immuno electron microscopy or when wheat germ agglutinin-purified extracts of the nuclei were subjected to PAGE, electrotransfer, and immunoblotting with anti-insulin receptor antibodies. These results suggested that internalized insulin dissociated from its receptor and accumulated in the nucleus without its membrane receptor. We propose that some of insulin's effects on nuclear function may be caused by the translocation of the intact and biologically active hormone to the nucleus and its binding to nuclear components in the heterochromatin.
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Woodcock, C. L., and H. Woodcock. "Nuclear matrix generation during reactivation of avian erythrocyte nuclei: an analysis of the protein traffic in cybrids." Journal of Cell Science 84, no. 1 (August 1, 1986): 105–27. http://dx.doi.org/10.1242/jcs.84.1.105.
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It has previously been shown that an internal nuclear matrix is generated during the reactivation of the chick erythrocyte nucleus in mouse L-cell cytoplasts. This experimental system has now been used to identify the major polypeptides that migrate into the nucleus during the reactivation process. Mouse L-cells were prelabelled with [35S]methionine, enucleated using cytochalasin B, and fused with 14- to 17-day embryonic chick erythrocytes. Sixteen hours post-fusion, the redistribution of the labelled proteins was examined by electron microscopic autoradiography, and two-dimensional polyacrylamide gel fluorography of the isolated nuclei was used to identify the major imported species. After allowing for cytoplasmic contamination, 15 nucleus-associated polypeptides were identified, two of which also matched with counterparts in the L-cell nuclear preparation. Five of the nucleus-associated polypeptides were tentatively identified (on the basis of one-dimensional gel matches) as nuclear matrix proteins; these five included the two that had counterparts in L-cell nuclei. The autoradiographic results showed that 16 h post-fusion, the specific activity (silver grains/unit area) of the reactivated nucleus was about half that of the cytoplasm, with no evidence for an accumulation of labelled protein at the nuclear periphery. When well-reactivated nuclei were distinguished from poorly reactivated nuclei on the basis of the extent of chromatin decondensation, it was found that their specific activities were quite similar, but because of the difference in size, the well-reactivated nuclei contained about twice as much labelled protein. Estimates of the protein traffic based upon the autoradiographic data indicated that the nuclei had increased in mass by 10–20% during the 16 h reactivation period.
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Goto, Chieko, Kentaro Tamura, Satsuki Nishimaki, Daisuke Maruyama, and Ikuko Hara-Nishimura. "The nuclear envelope protein KAKU4 determines the migration order of the vegetative nucleus and sperm cells in pollen tubes." Journal of Experimental Botany 71, no. 20 (August 10, 2020): 6273–81. http://dx.doi.org/10.1093/jxb/eraa367.
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Abstract A putative component protein of the nuclear lamina, KAKU4, modulates nuclear morphology in Arabidopsis thaliana seedlings, but its physiological significance is unknown. KAKU4 was highly expressed in mature pollen grains, each of which has a vegetative cell and two sperm cells. KAKU4 protein was highly abundant on the envelopes of vegetative nuclei and less abundant on the envelopes of sperm cell nuclei in pollen grains and elongating pollen tubes. Vegetative nuclei are irregularly shaped in wild-type pollen. However, KAKU4 deficiency caused them to become more spherical. After a pollen grain germinates, the vegetative nuclei and sperm cells enter and move along the pollen tube. In the wild type, the vegetative nucleus preceded the sperm cell nuclei in >90% of the pollen tubes, whereas, in kaku4 mutants, the vegetative nucleus preceded the sperm cell nuclei in only about half of the pollen tubes. kaku4 pollen was less competitive for fertilization than wild-type pollen after pollination. These results led us to hypothesize that the nuclear shape in vegetative cells of pollen grains affects the orderly migration of the vegetative nucleus and sperm cells in pollen tubes.
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Coverley, D., CS Downes, P. Romanowski, and RA Laskey. "Reversible effects of nuclear membrane permeabilization on DNA replication: evidence for a positive licensing factor." Journal of Cell Biology 122, no. 5 (September 1, 1993): 985–92. http://dx.doi.org/10.1083/jcb.122.5.985.
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We have investigated the mechanism which prevents reinitiation of DNA replication within a single cell cycle by exploiting the observation that intact G2 HeLa nuclei do not replicate in Xenopus egg extract, unless their nuclear membranes are first permeabilized (Leno et al., 1992). We have asked if nuclear membrane permeabilization allows escape of a negative inhibitor from the replicated nucleus or entry of a positive activator as proposed in the licensing factor hypothesis of Blow and Laskey (1988). We have distinguished these possibilities by repairing permeabilized nuclear membranes after allowing soluble factors to escape. Membrane repair of G2 nuclei reverses the effects of permeabilization arguing that escape of diffusible inhibitors is not sufficient to allow replication, but that entry of diffusible activators is required. Membrane repair has no significant effect on G1 nuclei. Pre-incubation of permeable G2 nuclei in the soluble fraction of egg extract before membrane repair allows semiconservative DNA replication of these nuclei when incubated in complete extract. Addition of the same fraction after membrane repair has no effect. Our results provide direct evidence for a positively acting "licensing" activity which is excluded form the interphase nucleus by the nuclear membrane. Nuclear membrane permeabilization and repair can be used as an assay for licensing activity which could lead to its purification and subsequent analysis of its action within the nucleus.
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Freyter, Benjamin M., Mutaz A. Abd Al-razaq, Anna Isermann, Anne Dietz, Omid Azimzadeh, Liesbeth Hekking, Maria Gomolka, and Claudia E. Rübe. "Nuclear Fragility in Radiation-Induced Senescence: Blebs and Tubes Visualized by 3D Electron Microscopy." Cells 11, no. 2 (January 13, 2022): 273. http://dx.doi.org/10.3390/cells11020273.
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Irreparable DNA damage following ionizing radiation (IR) triggers prolonged DNA damage response and induces premature senescence. Cellular senescence is a permanent state of cell-cycle arrest characterized by chromatin restructuring, altered nuclear morphology and acquisition of secretory phenotype, which contributes to senescence-related inflammation. However, the mechanistic connections for radiation-induced DNA damage that trigger these senescence-associated hallmarks are poorly understood. In our in vitro model of radiation-induced senescence, mass spectrometry-based proteomics was combined with high-resolution imaging techniques to investigate the interrelations between altered chromatin compaction, nuclear envelope destabilization and nucleo-cytoplasmic chromatin blebbing. Our findings confirm the general pathophysiology of the senescence-response, with disruption of nuclear lamin organization leading to extensive chromatin restructuring and destabilization of the nuclear membrane with release of chromatin fragments into the cytosol, thereby activating cGAS-STING-dependent interferon signaling. By serial block-face scanning electron microscopy (SBF-SEM) whole-cell datasets were acquired to investigate the morphological organization of senescent fibroblasts. High-resolution 3-dimensional (3D) reconstruction of the complex nuclear shape allows us to precisely visualize the segregation of nuclear blebs from the main nucleus and their fusion with lysosomes. By multi-view 3D electron microscopy, we identified nanotubular channels formed in lamin-perturbed nuclei of senescent fibroblasts; the potential role of these nucleo-cytoplasmic nanotubes for expulsion of damaged chromatin has to be examined.
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Stochaj, U., M. Osborne, T. Kurihara, and P. Silver. "A yeast protein that binds nuclear localization signals: purification localization, and antibody inhibition of binding activity." Journal of Cell Biology 113, no. 6 (June 15, 1991): 1243–54. http://dx.doi.org/10.1083/jcb.113.6.1243.
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Short stretches of amino acids, termed nuclear localization sequences (NLS), can mediate assembly of proteins into the nucleus. Proteins from the yeast, Saccharomyces cerevisiae, have been identified that specifically recognize nuclear localization peptides (Silver, P., I. Sadler, and M. A. Osborne. 1989. J. Cell Biol. 109:983-989). We now further define the role of one of these NLS-binding proteins in nuclear protein localization. The NLS-binding protein of 70-kD molecular mass can be purified from salt extracts of nuclei. Antibodies raised against the NLS-binding protein localized the protein mainly to the nucleus with minor amounts in the cytoplasm. These antibodies also inhibited the association of NLS-protein conjugates with nuclei. Incubation of nuclei with proteases coupled to agarose removed NLS-binding protein activity. Extracts enriched for NLS-binding proteins can be added back to salt or protease-treated nuclei to restore NLS-binding activity. These results suggest that the first step of nuclear protein import can be reconstituted in vitro.
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Auld, Alexander L., and Eric S. Folker. "Nucleus-dependent sarcomere assembly is mediated by the LINC complex." Molecular Biology of the Cell 27, no. 15 (August 2016): 2351–59. http://dx.doi.org/10.1091/mbc.e16-01-0021.
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Two defining characteristics of muscle cells are the many precisely positioned nuclei and the linearly arranged sarcomeres, yet the relationship between these two features is not known. We show that nuclear positioning precedes sarcomere formation. Furthermore, ZASP-GFP, a Z-line protein, colocalizes with F-actin in puncta at the cytoplasmic face of nuclei before sarcomere assembly. In embryos with mispositioned nuclei, ZASP-GFP is still recruited to the nuclei before its incorporation into sarcomeres. Furthermore, the first sarcomeres appear in positions close to the nuclei, regardless of nuclear position. These data suggest that the interaction between sarcomere proteins and nuclei is not dependent on properly positioned nuclei. Mechanistically, ZASP-GFP localization to the cytoplasmic face of the nucleus did require the linker of nucleoskeleton and cytoskeleton (LINC) complex. Muscle-specific depletion of klarsicht (nesprin) or klariod (SUN) blocked the recruitment of ZASP-GFP to the nucleus during the early stages of sarcomere assembly. As a result, sarcomeres were poorly formed and the general myofibril network was less stable, incomplete, and/or torn. These data suggest that the nucleus, through the LINC complex, is crucial for the proper assembly and stability of the sarcomere network.
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Bkaily, Ghassan, Moni Nader, Levon Avedanian, Danielle Jacques, Claudine Perrault, Dima Abdel-Samad, Pedro D'Orléans-Juste, Fernand Gobeil, and Khaled M. Hazzouri. "Immunofluorescence revealed the presence of NHE-1 in the nuclear membranes of rat cardiomyocytes and isolated nuclei of human, rabbit, and rat aortic and liver tissues." Canadian Journal of Physiology and Pharmacology 82, no. 8-9 (July 1, 2004): 805–11. http://dx.doi.org/10.1139/y04-119.
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Using immunofluorescence and 3-dimensional confocal microscopy techniques, the present study was designed to verify if NHE-1 is present at the level of the nuclear membrane in cells that are known to express this type of exchanger. Nuclei were isolated from aortic tissues of adult human, rabbit, and rats, as well as from liver tissues of human fetus, and adult rabbit and rat. In addition, cultured ventricular cardiomyocytes were isolated from 2-week-old rat. Our results showed the presence of NHE-1 in isolated nuclei of aortic vascular smooth muscle and liver of human, rabbit, and rat. NHE-1 seems to be distributed throughout the isolated nucleus and more particularly at the level of the nuclear membranes. The relative fluorescence density of NHE-1 was significantly higher (p < 0.05) in isolated liver nuclei of human, when compared with those of rabbit and rat. However, in isolated nuclei of aortic vascular smooth muscle, the relative fluorescence density of NHE-1 was significantly (p < 0.001) higher in the rabbit when compared with human and rat. In cultured rat ventricular cardiomyocytes, NHE-1 fluorescent labeling could be easily seen throughout the cell, including the nucleus, and more particularly at both the sarcolemma and the nuclear membranes. In rat cardiomyocytes, the relative fluorescence density of NHE-1 of the sarcolemma membrane, including the cytosol, was significantly lower than that of the whole nucleus (including the nuclear envelope membranes). In conclusion, our results showed that NHE-1 is present at the nuclear membranes and in the nucleoplasm and its distribution and density may depend on cell type and species used. These results suggest that nuclear membranes' NHE-1 may play a role in the modulation of intranuclear pH.Key words: NHE-1, heart, aorta, liver, nuclear membranes, nucleus.
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Nguyen, Son An, and Lanh Dang. "Application of single particle model to determine the spin and parity of levels of 59Fe nucleus." Science and Technology Development Journal 18, no. 1 (March 31, 2015): 92–101. http://dx.doi.org/10.32508/stdj.v18i1.1038.
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The spin and parity of the excited state and the ground state of nuclei are two of important properties of the nuclei quantum. However, up to now we do not have appropriate equipments to directly detetmine the spin and parity of nuclei. This paper shows the application of nuclear shell model to study the spin and parity of intermediate levels and ground state of 59Fe nucleus. Comparing to previously experimental data, this nucleus singleparticle model is suitable of the average mass and odd A nuclei.
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Oegema, K., W. F. Marshall, J. W. Sedat, and B. M. Alberts. "Two proteins that cycle asynchronously between centrosomes and nuclear structures: Drosophila CP60 and CP190." Journal of Cell Science 110, no. 14 (July 15, 1997): 1573–83. http://dx.doi.org/10.1242/jcs.110.14.1573.
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Both the nucleus and the centrosome are complex, dynamic structures whose architectures undergo cell cycle-specific rearrangements. CP190 and CP60 are two Drosophila proteins of unknown function that shuttle between centrosomes and nuclei in a cell cycle-dependent manner. These two proteins are associated in vitro, and localize to centrosomes in a microtubule independent manner. We injected fluorescently labeled, bacterially expressed CP190 and CP60 into living Drosophila embryos and followed their behavior during the rapid syncytial blastoderm divisions (nuclear cycles 10–13). Using quantitative 3-D wide-field fluorescence microscopy, we show that CP190 and CP60 cycle between nuclei and centrosomes asynchronously with the accumulation of CP190 leading that of CP60 both at centrosomes and in nuclei. During interphase, CP190 is found in nuclei. Immediately following nuclear envelope breakdown, CP190 localizes to centrosomes where it remains until telophase, thereafter accumulating in reforming nuclei. Unlike CP190, CP60 accumulates at centrosomes primarily during anaphase, where it remains into early interphase. During nuclear cycles 10 and 11, CP60 accumulates in nuclei simultaneous with nuclear envelope breakdown, suggesting that CP60 binds to an unknown nuclear structure that persists into mitosis. During nuclear cycles 12 and 13, CP60 accumulates gradually in nuclei during interphase, reaching peak levels just before nuclear envelope breakdown. Once in the nucleus, both CP190 and CP60 appear to form fibrous intranuclear networks that remain coherent even after nuclear envelope breakdown. The CP190 and CP60 networks do not co-localize extensively with each other or with DNA. This work provides direct evidence, in living cells, of a coherent protein network that may represent a nuclear skeleton.
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Nikulitskiy, S. I., E. G. Tyrsina, A. N. Inshakov, and N. B. Borovkova. "New method of extraction of intact nuclei from cells for flow cytometry fluorescence immunoassay." Russian Journal of Biotherapy 15, no. 2 (June 30, 2016): 76–81. http://dx.doi.org/10.17650/1726-9784-2016-15-2-76-81.
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Background. Identification of cellular proteins can be performed by indirect immunofluorescence assay using flow cytometry. However, this method allows to detect cellular proteins that are either on the cell surface or inside the cell and cannot demonstrate a protein distribution within cellular compartments, particularly in nucleus. Meanwhile, the nuclear localization of the protein of interest in many respects gives an indication of the mechanisms of its action. Therefore, the development of the protocol of extraction of nuclei suitable for analysis on a flow cytometer is able to complement the information about the localization and functional significance of many nucleus-associated proteins. Objective. The aim of this study was to develope a method for extraction, purification and stabilization of intact nuclei suitable for flow cytofluorimetry analysis. Materials and methods. In this work we studied the nuclear localization of the receptor type 1 for vascular endothelial growth factor (VEGF-R1). The A431 human cancer cell line was used as an object of the study. The quality of extracted nuclei was assessed by microscopic examination of stained smears of nuclear suspension. Expression of the receptor was determined by indirect immunofluorescence assay using flow cytometry. Results. New method was successfully applied to obtain the suspension of intact cellular nuclei that is crucial to perform further flow cytometry. Applied method revealed the presence of the receptor type 1 for vascular endothelial growth factor at the external nuclear membrane and inside of the nucleus. Interesting to note that the presence of the receptor type 1 for vascular endothelial growth factor inside ofthe nucleus was 3,8 times as much as its surface location (17,9 ± 1,04 % and 4,8 + 0,26 % respectively). Conclusions. The new method of extraction, purification and stabilization ofthe nuclei is applicable for proteins identification by flow cytometry. In combination with other methods (ICC, Western blotting, etc.) flow cytometry of intact nuclei is able to complement the information about the properties of nucleus-associated proteins.
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Merdes, A., and D. W. Cleveland. "The role of NuMA in the interphase nucleus." Journal of Cell Science 111, no. 1 (January 1, 1998): 71–79. http://dx.doi.org/10.1242/jcs.111.1.71.
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NuMA is an essential protein for the formation of spindle poles in mitosis. During interphase, NuMA is transported into the nucleus where it resides until prometaphase of the next mitotic cycle. We tested for a potential function of NuMA in interphase nuclei that were assembled from human sperm DNA using frog egg extract immunodepleted of NuMA. Despite the absence of NuMA, nuclei formed without visible changes of the chromatin structure, surrounded by an intact nuclear membrane containing pores and nuclear lamins. These nuclei were fully competent to import nuclear substrates and to replicate their DNA. By screening tissue sections of various organs, absence of NuMA from the nucleus was observed in a number of cell types, including sperm, granulocytes in the blood, and differentiated smooth and skeletal muscle fibers. Experiments on cultured myoblasts indicated that NuMA is degraded during muscle cell differentiation. The absence of NuMA in interphase nuclei of the tissues tested correlated with a non-spherical, elongated or beaded nuclear morphology, suggesting that during interphase NuMA may act as a non-essential nucleoskeletal element.
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Cejas, Romina B., Yohana C. Garay, Sofia de la Fuente, Ricardo D. Lardone, and Fernando J. Irazoqui. "Core 1 O-N-acetylgalactosamine (O-GalNAc) glycosylation in the human cell nucleus." Biological Chemistry 401, no. 9 (August 27, 2020): 1041–51. http://dx.doi.org/10.1515/hsz-2019-0448.
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AbstractGlycosylation is a very frequent post-translational modification in proteins, and the initiation of O-N-acetylgalactosamine (O-GalNAc) glycosylation has been recently described on relevant nuclear proteins. Here we evaluated the nuclear incorporation of a second sugar residue in the biosynthesis pathway of O-GalNAc glycans to yield the terminal core 1 glycan (C1G, Galβ3GalNAcαSer/Thr). Using confocal microscopy, enzymatic assay, affinity chromatography, and mass spectrometry, we analyzed intact cells, purified nuclei and soluble nucleoplasms to identify the essential factors for C1G biosynthesis in the cell nucleus. The enzyme C1GalT1 responsible for C1G synthesis was detected inside the nucleus, while catalytic activity of C1Gal-transferase was present in nucleoplasm and purified nuclei. In addition, C1G were detected in the nucleus inside of intact cells, and nuclear proteins exposing C1G were also identified. These evidences represent the first demonstration of core 1 O-GalNAc glycosylation of proteins in the human cell nucleus. These findings reveal a novel post-translational modification on nuclear proteins, with relevant repercussion in epigenetic and chemical biology areas.
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W. KAMINSKYJ, S. G., K. S. YOON, and I. B. HEATH. "Cytoskeletal interactions with post-mitotic migrating nuclei in the oyster mushroom fungus, Pleurotus ostreatus: evidence against a force-generating role for astral microtubules." Journal of Cell Science 94, no. 4 (December 1, 1989): 663–74. http://dx.doi.org/10.1242/jcs.94.4.663.
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Nuclei of Pleurotus ostreatus migrate in a highly predictable manner following conjugate mitosis at clamp connections. Parameters were determined by observations in living hyphae and these data were used to predict the living behaviour of freezesubstituted nuclei. Three of four classes of nucleus migrate immediately after telophase and move at similar speeds. Freeze-substitution electron microscopy shows that these nuclei have prominent nucleus-associated organelles (NAOs) with large astral microtubule (MT) arrays. Although the NAOs do not have a consistent position with respect to the nuclear motion, they are preferentially located near the hyphal axis. The fourth class of nucleus remains in the developing clamp until it fuses with the main hypha, whereupon it migrates to its interphase position at a rate much faster than the other classes. This class of nucleus has a small NAO and no astral MTs. Treatment of hyphae with a MTdisrupting drug, MBC, reduced the astral arrays in the first three classes but did not slow their rate of movement. Moreover, serial section analysis of drug-treated nuclei whose migration rate at the time of fixation was known showed no relationship, positive or negative, between astral MT number and rate of movement. These data suggest that astral MTs neither generate nor transduce force for post-mitotic nuclear migration in P. ostreatus. The role of astral MTs and possible mechanisms of postmitotic nuclear migration are discussed.
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Pignard, Olivier. "Strong/nuclear force in the dynamic medium of reference (DMR) theory. Nuclear deflection of light, nuclear time delay of light, and proposed experiment." Physics Essays 34, no. 4 (December 5, 2021): 517–28. http://dx.doi.org/10.4006/0836-1398-34.4.517.
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The theory of the dynamic medium of reference has already been presented in several articles [Pignard, Phys. Essays 32, 422 (2019); 33, 395 (2020); 34, 61 (2021); 34, 279 (2021)], and in particular in Pignard, Phys. Essays 32, 422 (2019). The article [Pignard, Phys. Essays 34, 279 (2021)] gives an explanation and mathematical developments of the gravitational acceleration from atomic nuclei of a massive body. General relativity considers a massive body, like the Earth or the Sun, globally, macroscopically, simply as an object of mass M (which curves space‐time). However, when one goes into details, this mass M is made up of atoms which are themselves mainly made up of nuclei of nucleons (if we neglect the mass of electrons in comparison of that of the nucleus). Thus, it is mainly the nuclei of a massive body that create the force of gravity! The dynamic medium of reference theory determines the gravitational acceleration microscopically by taking into account all the atomic nuclei that make up a massive body [Pignard, Phys. Essays 32, 422 (2019)]. This creates a strong link between gravity and the nuclear domain. This article goes further with the description of a model of the atomic nucleus. This makes it possible to establish that the strong force or nuclear force, which ensures the cohesion of the nucleus, is due to the strong acceleration of the flux of the medium which is a vector average of the flux of gravitons. This gives an expression of the nuclear force similar to the force of gravity but with a constant K ≈ 1031 m s−2, much higher than the gravitational constant G. This article shows that the functioning, the mechanism of the nucleus, makes it possible to explain the nuclear force and also to find the gravitational acceleration. From there, it is deduced that the photons are deflected by the strong acceleration due to an atom nucleus. They are also slowed down by an atom nucleus which creates a delay in their travel time which we call the nuclear time delay of light. Finally, an experiment is proposed to verify the phenomenon of nuclear deflection of light and the nuclear time delay of light.
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NAGAHIRO, HIDEKO, DAISUKE JIDO, and SATORU HIRENZAKI. "FORMATION OF η-MESIC NUCLEI BY (π, N) REACTION AND CHIRAL SYMMETRY FOR BARYONS." International Journal of Modern Physics E 18, no. 10 (November 2009): 2202–6. http://dx.doi.org/10.1142/s0218301309014561.
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We calculate formation spectra of η-nucleus systems in (π, N) reactions with nuclear targets, which can be performed at existing and/or forthcoming facilities, including J-PARC, in order to investigate η-nucleus interactions. Based on the N*(1535) dominance in the ηN system, η-mesic nuclei are suitable systems for study of in-medium properties of the N*(1535) baryon resonance, such as reduction of the mass difference of N and N* in nuclear medium, which affects level structure of the η and N*-hole modes. We find that clear information on the in-medium N*- and η-nucleus interactions can be obtained through the formation spectra of the η-mesic nuclei.
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Sakamoto, Kazushi, Sergio Martín, David J. Wilner, Susanne Aalto, Aaron S. Evans, and Nanase Harada. "Deeply Buried Nuclei in the Infrared-luminous Galaxies NGC 4418 and Arp 220. II. Line Forests at λ = 1.4–0.4 mm and Circumnuclear Gas Observed with ALMA." Astrophysical Journal 923, no. 2 (December 1, 2021): 240. http://dx.doi.org/10.3847/1538-4357/ac29bf.
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Abstract We present the line observations in our Atacama Millimeter-Submillimeter Array imaging spectral scan toward three deeply buried nuclei in NGC 4418 and Arp 220. We cover 67 GHz in f rest = 215–697 GHz at about 0.″2 (30, 80 pc) resolution. All the nuclei show dense line forests; we report our initial line identification using 55 species. The line velocities generally indicate gas rotation around each nucleus, tracing nuclear disks of ∼100 pc in size. We confirmed the counter-rotation of the nuclear disks in Arp 220 and that of the nuclear disk and the galactic disk in NGC 4418. While the brightest lines exceed 100 K, most of the major lines and many 13C isotopologues show absorption against even brighter continuum cores of the nuclei. The lines with higher upper-level energies, including those from vibrationally excited molecules, tend to arise from smaller areas, indicating radially varying conditions in these nuclei. The outflows from the two Arp 220 nuclei cause blueshifted line absorption below the continuum level. The absorption mostly has small spatial offsets from the continuum peaks to indicate the outflow orientations. The bipolar outflow from the western nucleus is also imaged in multiple emission lines, showing the extent of ∼1″ (400 pc). Redshifted line absorption against the nucleus of NGC 4418 indicates either an inward gas motion or a small collimated outflow slanted to the nuclear disk. We also resolved some previous confusions due to line blending and misidentification.
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Hartig, R., R. L. Shoeman, A. Janetzko, G. Tolstonog, and P. Traub. "DNA-mediated transport of the intermediate filament protein vimentin into the nucleus of cultured cells." Journal of Cell Science 111, no. 24 (December 18, 1998): 3573–84. http://dx.doi.org/10.1242/jcs.111.24.3573.
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A number of characteristic properties of intermediate filament (IF) proteins, such as nucleic acid-binding activity, affinity for histones and structural relatedness to transcription factors and nuclear matrix proteins, in conjunction with the tight association of IFs with the nucleus, suggest that these proteins might also fulfill nuclear functions in addition to their structure-organizing and -stabilizing activities in the cytoplasm. Yet, cytoplasmic IF proteins do not possess nuclear localization signals. In a search for carriers capable of transporting the IF protein vimentin into the nucleus, complexes of FITC-vimentin with various DNAs were microinjected into the cytoplasm of cultured cells and the intracellular distribution of the protein was followed by confocal laser scanning microscopy. The single-stranded oligodeoxyribonucleotides oligo(dG)25, oligo[d(GT)12G] and oligo[d(G3T2A)4G] proved to be excellent nuclear carriers for vimentin. However, in fibroblasts, fluorescence-labeled vimentin taken up by the nuclei remained undetectable with affinity-purified, polyclonal anti-vimentin antibody, whereas it was readily identifiable in the nuclei of microinjected epithelial cells in this way. Moreover, when FITC-vimentin was preinjected into fibroblasts and allowed to assemble into the endogenous vimentin filament system, it was still transferred into the nucleus by post-injected oligo(dG)25, although to a lesser extent. Superhelical circular DNAs, like pBR322, SV40 and mitochondrial DNA, were also characterized by considerable capacities for nuclear vimentin transport; these transport potentials were totally destroyed by relaxation or linearization of the DNA molecules. Nevertheless, certain linear double-stranded DNA molecules with a high affinity for vimentin IFs, such as repetitive telomere and centromere or mobile long interspersed repeat (LINE) DNA, could carry FITC-vimentin into the nucleus. This was also true for a 375 bp extrachromosomal linear DNA fragment which occurs in the cytoplasm of mouse tumor cells and which is capable of immortalizing human lymphocytes. On the basis of these results, it appears very likely that cellular and viral products of reverse transcription as well as other extrachromosomal DNAs, which are circular, superhelical and apparently shuttling between the cytoplasm and the nucleus (eccDNA), are constantly loaded with vimentin in vimentin-positive cells. Since such DNAs are considered as markers of genomic instability, it is conceivable that vimentin directly participates as an architectural, chromatin-modifying protein in recombinatorial processes set off by these DNAs in the nucleus.
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Misteli, T., and D. L. Spector. "Serine/threonine phosphatase 1 modulates the subnuclear distribution of pre-mRNA splicing factors." Molecular Biology of the Cell 7, no. 10 (October 1996): 1559–72. http://dx.doi.org/10.1091/mbc.7.10.1559.
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HeLa cell nuclei were permeabilized and reconstituted with nuclear extract to identify soluble nuclear factors which play a role in the organization of pre-mRNA splicing factors in the mammalian cell nucleus. Permeabilized nuclei reconstituted with nuclear extract were active in transcription and DNA replication and nuclear speckles containing pre-mRNA splicing factors were maintained over several hours independent of soluble nuclear components. The characteristic rounding up of nuclear speckles in response to inhibition of RNA polymerase II seen in vivo was reproduced in permeabilized cells and was strictly dependent on a catalytic activity present in the nuclear extract. By inhibitor titration experiments and sensitivity to inhibitor 2, this activity was identified as a member of the serine/threonine protein phosphatase 1 family (PP1). Interference with PP1 activity affected the distribution of pre-mRNA splicing factors in transcriptionally active, permeabilized cells, and excess PP1 activity caused increased dephosphorylation of SR proteins in nuclear speckles. These data show that the dynamic reorganization of the mammalian cell nucleus can be studied in permeabilized cells and that PP1 is involved in the rounding up of speckles as well as the overall organization of pre-mRNA splicing factors in the mammalian cell nucleus.
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Sullivan, W., J. S. Minden, and B. M. Alberts. "daughterless-abo-like, a Drosophila maternal-effect mutation that exhibits abnormal centrosome separation during the late blastoderm divisions." Development 110, no. 2 (October 1, 1990): 311–23. http://dx.doi.org/10.1242/dev.110.2.311.
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daughterless-abo-like (dal) is a maternal-effect semilethal mutation in Drosophila. The nuclear divisions of embryos derived from homozygous dal females are normal through nuclear cycle 10. However, during nuclear cycles 11, 12 and 13, a total of about half of the nuclei in each embryo either fail to divide or fuse with a neighboring nucleus during telophase. These abnormal nuclei eventually sink into the interior of the embryo, leaving their centrosomes behind on the surface. The loss of about one-half of the peripheral nuclei into the interior of the embryo results in these embryos cellularizing during nuclear cycle 14 with about one-half the normal number of cells. Surprisingly, many of these embryos develop a nearly normal larval cuticle and 8% develop to adulthood. Observations of live embryos doubly injected with tubulin and histones that have been fluorescently labeled allows nuclear and centrosomal behavior to be directly followed as the embryo develops. We find that the abnormal nuclei arise from nuclei whose centrosomes have failed to separate normally in the previous interphase. These incompletely separated centrosomes can cause a non-functional spindle to form, leading to a nuclear division failure. Alternatively, they can form an abnormal spindle with a centrosome from a neighboring nucleus, causing two nuclei to share a common spindle pole. Such nuclei with a shared centrosome will undergo telophase fusions, unequal divisions, or division failures later in mitosis. These findings have helped us to understand the function of the centrosome in the Drosophila embryo.
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BEREZHNOY, YU A., and V. YU KORDA. "DEUTERON-NUCLEUS INTERACTION AT INTERMEDIATE ENERGIES." International Journal of Modern Physics E 03, no. 01 (March 1994): 149–70. http://dx.doi.org/10.1142/s021830139400005x.
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The deuteron-nucleus interaction has been studied in the approximation where the deuteron radius and the nuclear surface diffuseness are small compared with the nuclear radius. The closed formulae have been derived for the integrated cross-sections of different deuteron-nucleus interaction processes and for differential cross-sections of the deuteron elastic scattering and the deuteron inelastic scattering with excitation of the low lying vibrational states of nuclei. It is shown that the allowance for nuclear surface diffuseness substantially influences the values of the different deuteron-nucleus reaction cross-sections.
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Neumann, Frank R., and Paul Nurse. "Nuclear size control in fission yeast." Journal of Cell Biology 179, no. 4 (November 12, 2007): 593–600. http://dx.doi.org/10.1083/jcb.200708054.
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A long-standing biological question is how a eukaryotic cell controls the size of its nucleus. We report here that in fission yeast, nuclear size is proportional to cell size over a 35-fold range, and use mutants to show that a 16-fold change in nuclear DNA content does not influence the relative size of the nucleus. Multi-nucleated cells with unevenly distributed nuclei reveal that nuclei surrounded by a greater volume of cytoplasm grow more rapidly. During interphase of the cell cycle nuclear growth is proportional to cell growth, and during mitosis there is a rapid expansion of the nuclear envelope. When the nuclear/cell (N/C) volume ratio is increased by centrifugation or genetic manipulation, nuclear growth is arrested while the cell continues to grow; in contrast, low N/C ratios are rapidly corrected by nuclear growth. We propose that there is a general cellular control linking nuclear growth to cell size.
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Jans, D. A., L. J. Briggs, P. Jans, C. J. Froelich, G. Parasivam, S. Kumar, V. R. Sutton, and J. A. Trapani. "Nuclear targeting of the serine protease granzyme A (fragmentin-1)." Journal of Cell Science 111, no. 17 (September 1, 1998): 2645–54. http://dx.doi.org/10.1242/jcs.111.17.2645.
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Cytolytic granule-mediated target cell killing is effected in part through synergistic action of the membrane-acting protein perforin and serine proteases such as granzymes A (GrA) or B (GrB). In the present study we examine GrA cellular entry and nuclear uptake in intact mouse myeloid FDC-P1 cells exposed to perforin using confocal laser scanning microscopy, as well as reconstitute GrA nuclear uptake in vitro. GrA alone was found to be able to enter the cytoplasm of intact cells but did not accumulate in nuclei. In the presence of perforin, it specifically accumulated in the cell nuclei, with maximal levels about 2.5 times those in the cytoplasm after 2. 5 hours. In vitro, GrA accumulated in the nucleus and nucleolus maximally to levels that were four- and sixfold, respectively, those in the cytoplasm. In contrast, the active form of the apoptotic cysteine protease CPP32 did not accumulate in nuclei in vitro. Nuclear/nucleolar import of GrA in vitro was independent of ATP and not inhibitable by the non-hydrolyzable GTP analog GTPgammaS, but was dependent on exogenously added cytosol. Importantly, GrA was found to be able to accumulate in the nucleus of semi-intact cells in the presence of the nuclear envelope-permeabilizing detergent CHAPS, implying that the mechanism of nuclear accumulation was through binding to insoluble factors in the nucleus. GrB was found for the first time to be similar in this regard. The results support the contention that GrA and GrB accumulate in the nucleus through a novel nuclear import pathway, and that this is integral to induction of the nuclear changes associated with cytolytic granule-mediated apoptosis.
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Chisoi, Anca, Mariana Aşchie, and I. Poinăreanu. "Morphometric Characterization of Small Cell Lymphocytic Lymphoma." ARS Medica Tomitana 20, no. 4 (November 1, 2014): 179–83. http://dx.doi.org/10.1515/arsm-2015-0002.
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Abstract The morphometry in histopathology is used to characterize cell populations belonging to different tissues and to identify differences in their parameters with prognostic implications. To achieve morphometric examination were selected 6 of 24 cases identified as small cell lymphocytic lymphoma. For each case analysis was done on five fields, for each field measuring the parameters of 20 cells. The studied parameters were for cytoplasm: cytoplasmic area, maximum and minimum cytoplasmic diameter, cytoplasmic perimeter; for nucleus were measured: nuclear area, minimum and maximum nuclear diameter, nuclear perimeter, nuclear contour index, nuclear ellipticity index, nuclear irregularity index. Also the nucleocytoplasmic ratio was calculated in all studied cases. Small cell lymphocytic lymphoma is characterized in morphometric terms having a small cytoplasmic area (average 29.206) and also a small nuclear area (mean 28.939) having a nucleo-cytoplasmic ratio appearance suggestive for adult lymphocyte. A nuclear contour index small value (3.946), ellipticity index value also small (3.521) and small nuclear irregularity index (3.965). Standard deviations, in any of the studied morphometric categories, is around or below 1 suggesting monomorphic cell appearance. These morphometric and microscopic features characterized mainly by a small population of adult lymphocytes, monomorphic, with rounded hipercromic nuclei, dense chromatin, support the framing into indolent lymphoma group in terms of clinical outcome.
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Domínguez, Fernando, and Francisco J. Cejudo. "Identification of a nuclear-localized nuclease from wheat cells undergoing programmed cell death that is able to trigger DNA fragmentation and apoptotic morphology on nuclei from human cells." Biochemical Journal 397, no. 3 (July 13, 2006): 529–36. http://dx.doi.org/10.1042/bj20051809.
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PCD (programmed cell death) in plants presents important morphological and biochemical differences compared with apoptosis in animal cells. This raises the question of whether PCD arose independently or from a common ancestor in plants and animals. In the present study we describe a cell-free system, using wheat grain nucellar cells undergoing PCD, to analyse nucleus dismantling, the final stage of PCD. We have identified a Ca2+/Mg2+ nuclease and a serine protease localized to the nucleus of dying nucellar cells. Nuclear extracts from nucellar cells undergoing PCD triggered DNA fragmentation and other apoptotic morphology in nuclei from different plant tissues. Inhibition of the serine protease did not affect DNA laddering. Furthermore, we show that the nuclear extracts from plant cells triggered DNA fragmentation and apoptotic morphology in nuclei from human cells. The inhibition of the nucleolytic activity with Zn2+ or EDTA blocked the morphological changes of the nucleus. Moreover, nuclear extracts from apoptotic human cells triggered DNA fragmentation and apoptotic morphology in nuclei from plant cells. These results show that degradation of the nucleus is morphologically and biochemically similar in plant and animal cells. The implication of this finding on the origin of PCD in plants and animals is discussed.
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Goff, L. J., and A. W. Coleman. "The solution to the cytological paradox of isomorphy." Journal of Cell Biology 104, no. 3 (March 1, 1987): 739–48. http://dx.doi.org/10.1083/jcb.104.3.739.
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Cells with polyploid nuclei are generally larger than cells of the same organism or species with nonpolyploid nuclei. However, no such change of cell size with ploidy level is observed in those red algae which alternate isomorphic haploid with diploid generations. The results of this investigation reveal the explanation. Nuclear DNA content and other parameters were measured in cells of the filamentous red alga Griffithsia pacifica. Nuclei of the diploid generation contain twice the DNA content of those of the haploid generation. However, all cells except newly formed reproductive cells are multinucleate. The nuclei are arranged in a nearly perfect hexagonal array just beneath the cell surface. When homologous cells of the two generations are compared, although the cell size is nearly identical, each nucleus of the diploid cell is surrounded by a region of cytoplasm (a "domain") nearly twice that surrounding a haploid nucleus. Cytoplasmic domains associated with a diploid nucleus contain twice the number of plastids, and consequently twice the amount of plastid DNA, than is associated with the domain of a haploid nucleus. Thus, doubling of ploidy is reflected in doubling of the size and organelle content of the domain associated with each nucleus. However, cell size does not differ between homologous cells of the two generations, because total nuclear DNA (sum of the DNA in all nuclei in a cell) per cell does not differ. This is the solution to the cytological paradox of isomorphy.
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Rosenberger, U., M. Shakibaei, and K. Buchner. "Localization of non-conventional protein kinase C isoforms in bovine brain cell nuclei." Biochemical Journal 305, no. 1 (January 1, 1995): 269–75. http://dx.doi.org/10.1042/bj3050269.
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Using Western blotting and immunofluorescence microscopy we detected the protein kinase C isoforms delta, epsilon and zeta in isolated cell nuclei from bovine cerebral cortex. Both protein kinase C (PKC) delta and PKC epsilon are present in higher concentrations in neuronal than in glial nuclei and are located inside the nucleus and at the nuclear envelope. There they give a punctate staining in immunofluorescence microscopy. PKC zeta is also present both in the nucleoplasm and at the nuclear envelope. PKC eta could not be detected in the cell nuclei and, even in the homogenate of cerebral cortex, this isoform is present only in very low concentrations. The antibody against PKC eta bound strongly to a nucleoplasmic protein with an apparent molecular mass of 99 kDa. The localization of non-conventional PKC isoforms at the cell nucleus strongly indicates that these isoforms are directly involved in the regulation of nuclear processes.
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SURGULADZE, Nodar, Stephanie PATTON, Anna COZZI, Michael G. FRIED, and James R. CONNOR. "Characterization of nuclear ferritin and mechanism of translocation." Biochemical Journal 388, no. 3 (June 7, 2005): 731–40. http://dx.doi.org/10.1042/bj20041853.
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Ferritin, normally considered a cytoplasmic iron-storage protein, is also found in cell nuclei. It is an established fact that H-ferritin is the major form of nuclear ferritin, but little is known about the roles of ferritin in nuclei or about the mechanisms that control its appearance within the nuclear volume. In the present study, we show that, for human SW1088 astrocytoma cells, the nuclear and cytoplasmic forms of H-ferritin are products of the same mRNA. Histochemical and biochemical evidence is presented showing that ferritin is distributed non-randomly within the nuclear volume and that it preferentially associates with heterochromatin. Both cytoplasmic and nuclear populations of H-ferritin contain mixtures of non- and O-glycosylated forms, but the nuclear population is enriched in O-glycosylated forms. Cells treated with alloxan, a potent inhibitor of O-glycosylation, contained significantly less nuclear ferritin compared with cells grown in control media. Alloxan inhibited the reappearance of H-ferritin in nuclei of cells released from conditions of iron depletion, but did not prevent its disappearance from nuclei of cells undergoing iron depletion. These results suggest that O-glycosylation accompanies the transfer of ferritin from the cytoplasm to the nucleus, but does not influence the reverse process. The picture that emerges is one in which ferritin translocation between the cytoplasm and the nucleus is post-translationally regulated and responds to environmental and nutritional cues.
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Chang, Wakam, Eric S. Folker, Howard J. Worman, and Gregg G. Gundersen. "Emerin organizes actin flow for nuclear movement and centrosome orientation in migrating fibroblasts." Molecular Biology of the Cell 24, no. 24 (December 15, 2013): 3869–80. http://dx.doi.org/10.1091/mbc.e13-06-0307.
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In migrating fibroblasts, rearward movement of the nucleus orients the centrosome toward the leading edge. Nuclear movement results from coupling rearward-moving, dorsal actin cables to the nucleus by linear arrays of nesprin-2G and SUN2, termed transmembrane actin-associated nuclear (TAN) lines. A-type lamins anchor TAN lines, prompting us to test whether emerin, a nuclear membrane protein that interacts with lamins and TAN line proteins, contributes to nuclear movement. In fibroblasts depleted of emerin, nuclei moved nondirectionally or completely failed to move. Consistent with these nuclear movement defects, dorsal actin cable flow was nondirectional in cells lacking emerin. TAN lines formed normally in cells lacking emerin and were coordinated with the erratic nuclear movements, although in 20% of the cases, TAN lines slipped over immobile nuclei. Myosin II drives actin flow, and depletion of myosin IIB, but not myosin IIA, showed similar nondirectional nuclear movement and actin flow as in emerin-depleted cells. Myosin IIB specifically coimmunoprecipitated with emerin, and emerin depletion prevented myosin IIB localization near nuclei. These results show that emerin functions with myosin IIB to polarize actin flow and nuclear movement in fibroblasts, suggesting a novel function for the nuclear envelope in organizing directional actin flow and cytoplasmic polarity.
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Xu, Xiaoping, Meirong Ji, Bobin Chen, and Guowei Lin. "Analysis on Characteristics of Dysplasia in 345 Patients with Myelodysplastic Syndrome." Blood 112, no. 11 (November 16, 2008): 5100. http://dx.doi.org/10.1182/blood.v112.11.5100.5100.
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Abstract Objective To investigate the characteristics of dysplasia in myelodysplastic syndrome (MDS). Methods Collect 716 samples of adult patients with abnormal blood routine but unclear cause between July 04, 2003 and March 14, 2007. Based on the gold standard of WHO MDS classification, all cases were detected on cytomorphological observation, cytochemical stain, bone marrow pathological study, cytogenetics, flow cytometry, and ect. The bone marrow cytological study on some abnormal hematopoietic cells has a diagnostic value to determine clonal or non-clonal diseases and assess sensitivity and specificity. Results In the complicated various dysplasia of hematopoietic cells, the following characteristics can be the main basis of cytomorphological diagnosis: One of granular Auer bodies, micronucleus (MN), or nuclear budding; Erythroid nuclear budding; Megakaryocytes presented in peripheral blood; Myeloblast or prorubricyte exhibited in peripheral blood; ringed sideroblasts>1%. The subordinate basis of cytomorphological diagnosis was as follows: Granular pseudo Pelger-H≥et anomaly, hard nucleus segmentation, unsynchronous development of nuclei, ring-shaped nuclei, and aggregation of nuclear chromatin. Erythroid multi-nuclei, odd nucleus, mother-daughter nucleus, nuclear fragmentation, vacuole, and anisocytosis; micromegakaryocytes. Conclusion Cytomorphologic is the base for the diagnosis of MDS, however, it presents certain limit, especially cytomorphological change does not possess specificity for early MDS, hereby, it requires to combine other detection methods.
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Malviya, Anant N., and Christian Klein. "Mechanism regulating nuclear calcium signalingThis paper is one of a selection of papers published in this Special Issue, entitled The Nucleus: A Cell Within A Cell." Canadian Journal of Physiology and Pharmacology 84, no. 3-4 (March 2006): 403–22. http://dx.doi.org/10.1139/y05-130.
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Although the outer nuclear membrane is continuous with the endoplasmic reticulum, it is possible to isolate nuclei both intact and free from endoplasmic reticulum contaminants. The outer and the inner nuclear membranes can be purified free from cross-contamination. Evidence in support of autonomous regulation of nuclear calcium signaling relies upon the investigations with isolated nuclei. Mechanisms for generating calcium signaling in the nucleus have been identified. Two calcium transporting systems, an ATP-dependant nuclear Ca2+-ATPase and an IP4-mediated inositol 1,3,4,5-tetrakisphosphate receptor, are located on the outer nuclear membrane. Thus, ATP and IP4, depending on external free calcium concentrations, are responsible for filling the nuclear envelope calcium pool. The inositol 1,4,5-trisphosphate receptor is located on the inner nuclear membrane with its ligand binding domain facing toward the nucleoplasm. Likewise, the ryanodine receptor is located on the inner nuclear membrane and its ligand cADP-ribose is generated within the nucleus. A 120 kDa protein fragment of nuclear PLC-γ1 is stimulated in vivo by epidermal growth factor nuclear signaling coincident with the time course of nuclear membrane epidermal growth factor receptor activation. Stimulated 120 kDa protein fragment interacts with PIKE, a nuclear GTPase, and together they form a complex with PI[3]kinase serving as a module for nuclear PI[3]K stimulation. Thus, the nucleus has its own IP3 generating system.
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Gao, X. P., and J. Y. Li. "Nuclear division in the marine dinoflagellate Oxyrrhis marina." Journal of Cell Science 85, no. 1 (September 1, 1986): 161–75. http://dx.doi.org/10.1242/jcs.85.1.161.
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The nuclear division of Oxyrrhis marina is a very distinct one among the mitoses of dinoflagellates that have been studies. Using synchronized populations, we have investigated the ultrastructural changes in this nuclear division. In interphase, nuclei can be classified into two groups on the basis of the shapes of the chromosomes. Y- and U-shaped chromosomes have been observed in both types of interphase nuclei. By prophase the nucleus becomes oval, many nuclear plaques appear on the nuclear envelope, and many microtubules radiate from these nuclear plaques within the nucleus. Metaphase can be identified by the characteristic arrangement of the chromosomes; an equatorial metaphase plate is absent. As in many higher organisms, anaphase includes two stages: anaphase A and anaphase B. During anaphase A the nucleus does not apparently elongate and the chromosomes migrate towards the poles by a combination of the shortening of the chromosome-associated microtubules and the elongation of those located between daughter chromosomes. During anaphase B the nucleus elongates to about twice its former length. This elongation may result from growth of the interzonal nuclear envelope. Dividing nucleoli are associated with microtubules, which suggests that microtubules may play an active role in the division of the nucleolus. The evolution of mitosis and the phylogenetic relationships between Oxyrrhis, typical dinoflagellates and Syndinium are discussed.
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Cao, Y., M. Ekstrom, and R. F. Pettersson. "Characterization of the nuclear translocation of acidic fibroblast growth factor." Journal of Cell Science 104, no. 1 (January 1, 1993): 77–87. http://dx.doi.org/10.1242/jcs.104.1.77.
Full textAbstract:
The subcellular localization of human acidic FGF (aFGF; FGF-1) expressed to high levels by using a bacteriophage T7 RNA polymerase-driven vaccinia virus expression system was studied in BHK21 and HeLa cells. Acidic FGF was detected by immunoblotting or immunofluorescence using an affinity-purified rabbit polyclonal antibody. The nuclei of most transfected cells, but not nuclei of control cells, were strongly immunoreactive. The nuclear accumulation of aFGF was confirmed by subcellular fractionation and immunoblotting, indicating that about 50% of the expressed protein was located in the nuclei at 12 h after transfection. It has previously been reported that a putative N-terminal nuclear localization sequence (NLS) in aFGF is required for full mitogenic activity (Imamura et al., Science 249, 1567–1570, 1990). We found that deletion of the first 27 residues including the putative NLS did not prevent the nuclear translocation of aFGF in either cell type. This observation suggests that the putative NLS sequence is not essential for targeting aFGF to the cell nucleus. To analyze further the mechanism of nuclear import, purified aFGF was microinjected into the cytoplasm of growing BHK21 cells under various conditions. In chilled (4 degrees C) or ATP-depleted cells, the injected aFGF entered the nucleus with similar efficiency to that in control cells at 37 degrees C. This suggests that aFGF, which has a molecular mass of only 16,500, enters the cell nucleus by free diffusion, and possibly becomes trapped by binding to some nuclear structures. When added exogenously to growing BHK21 cells, aFGF was not localized to the nucleus. Instead, a punctate staining pattern in the cytosol was observed, reminiscent of that in the endosomal-lysosomal compartments. In addition, a diffuse extracellular surface-staining was evident. This result demonstrates that receptor-mediated endocytosis of aFGF does not result in its translocation to the nucleus, as has been reported for basic FGF.
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Kono, T., J. Carroll, K. Swann, and D. G. Whittingham. "Nuclei from fertilized mouse embryos have calcium-releasing activity." Development 121, no. 4 (April 1, 1995): 1123–28. http://dx.doi.org/10.1242/dev.121.4.1123.
Full textAbstract:
During mammalian fertilization, the sperm triggers a series of intracellular Ca2+ oscillations which initiate oocyte activation and the formation of pronuclei. Oocyte activation can be induced artificially by a variety of chemical and physical stimuli which elevate intracellular calcium. We show that the transfer of nuclei from 1- and 2-cell-stage fertilized mouse embryos to unfertilized oocytes stimulates the completion of meiosis and the formation of pronuclei. Nuclei from embryos that had developed to the 4-cell stage did not stimulate meiotic resumption. The ability to cause oocyte activation was specific to nuclei transferred from fertilized embryos as nuclei from parthenogenetic embryos or cytoplasts from fertilized or parthenogenetic embryos did not induce activation. Nucleus-induced oocyte activation was associated with the generation of intracellular Ca2+ transients, which were seen after nuclear envelope breakdown of the transferred nuclei. Treatment of the oocyte with the intracellular Ca2+ chelator, BAPTA, prior to nuclear transfer inhibited intracellular Ca2+ transients and oocyte activation. The specific Ca(2+)-releasing activity of the nucleus was not caused by sperm-induced protein synthesis since similar activity was present in nuclei originating from embryos exposed to cycloheximide throughout fertilization. The specific ability of nuclei from fertilized embryos to stimulate Ca2+ transients and oocyte activation was also found in nuclei from embryos parthenogenetically activated by the injection of a partially purified cytosolic sperm factor. The results suggest that the fertilizing sperm introduces Ca(2+)-releasing activity which becomes associated with the nucleus of early mammalian embryos.
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Maeda, Yasutaka, Hiroko Yanagimachi, Hiroyuki Tateno, Noriko Usui, and R. Yanagimachi. "Decondensation of the mouse sperm nucleus within the interphase nucleus." Zygote 6, no. 1 (February 1998): 39–45. http://dx.doi.org/10.1017/s0967199400005062.
Full textAbstract:
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.
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Kerr, Sylvia Joann. "Nuclear behavior during sporulation of the true slime mold Didymium nigripes." Canadian Journal of Botany 66, no. 4 (April 1, 1988): 687–93. http://dx.doi.org/10.1139/b88-099.
Full textAbstract:
Nuclear behavior during sporulation of the true slime mold Didymium nigripes Fries includes extensive episodes of nuclear degeneration of a magnitude not previously suspected, two mitotic divisions, and changes in nuclear morphology. Nuclear and nucleolar diameter are reduced and up to 60% of the nuclei present at the onset of sporulation degenerate. Didymium nigripes possesses nuclei of several ploidy levels throughout its life cycle, and ratios of these nuclear size classes change in random fashion during sporulation, presumably as a result of nuclear degeneration. This study demonstrates that the end result of nuclear degeneration is not the elimination of a single size class of nucleus.
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Hoffmann, Bernd, Sabine E. Eckert, Sven Krappmann, and Gerhard H. Braus. "Sexual Diploids of Aspergillus nidulans Do Not Form by Random Fusion of Nuclei in the Heterokaryon." Genetics 157, no. 1 (January 1, 2001): 141–47. http://dx.doi.org/10.1093/genetics/157.1.141.
Full textAbstract:
Abstract The sexual stage of Aspergillus (Emericella) nidulans consists of cleistothecia containing asci, each with eight ascospores. The fungus completes the sexual cycle in a homokaryotic or a heterokaryotic mycelium, respectively. The common assumption for the last 50 years was that different nuclear types are not distinguishable when sexual development is initiated. When cultured on a medium limited for glucose supplemented with 2% sorbitol, sexual development of A. nidulans is slowed and intact tetrads can be isolated. Through tetrad analysis we found that unlike haploid nuclei fuse preferentially to the prezygotic diploid nucleus. When heterokaryons are formed between nuclei of different genetic backgrounds, then recombinant asci derived from opposite nuclei are formed exclusively. Strains in the same heterokaryon compatibility group with moderate differences in their genetic backgrounds can discriminate between the nuclei of a heterokaryon and preferentially form a hybrid diploid nucleus, resulting in 85% recombinant tetrads. A. nidulans strains that differ at only a single genetic marker fuse the haploid nuclei at random for formation of diploid nuclei during meiosis. These results argue for a genetically determined “relative heterothallism” of nuclear recognition within a heterokaryon and a specific recruitment of different nuclei for karyogamy when available.
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Maher, P. A. "Nuclear Translocation of fibroblast growth factor (FGF) receptors in response to FGF-2." Journal of Cell Biology 134, no. 2 (July 15, 1996): 529–36. http://dx.doi.org/10.1083/jcb.134.2.529.
Full textAbstract:
Members of the FGF family of growth factors localize to the nuclei in a variety of different cell types. To determine whether FGF receptors are also present within nuclei and if this localization is regulated by FGFs, nuclei were prepared from quiescent and FGF-2-treated Swiss 3T3 fibroblasts and examined for the presence of FGF receptors by immunoblotting with an antibody produced against the extracellular domain of FGF receptor-1 (FGFR-1). Little or no FGFR-1 is detected in nuclei prepared from quiescent cells. When cells are treated with FGF-2, however, there is a time- and dose-dependent increase in the association of FGFR-1 immunoreactivity with the nucleus. In contrast, treatment with either EGF or 10% serum does not increase the association of FGFR-1 with the nucleus. When cell surface proteins are labeled with biotin, a biotinylated FGFR-1 is detected in the nuclear fraction prepared from FGF-2-treated, but not untreated, cells indicating that the nuclear-associated FGFR-1 immunoreactivity derives from the cell surface. The presence of FGFR-1 in the nuclei of FGF-2-treated cells was confirmed by immunostaining with a panel of different FGFR-1 antibodies, including one directed against the COOH-terminal domain of the protein. Fractionation of nuclei from FGF-2-treated cells indicates that nuclear FGFR-1 is localized to the nuclear matrix, suggesting that the receptor may play a role in regulating gene activity.
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Yanagi, A., and K. Hiwatashi. "Intracellular positional control of survival or degeneration of nuclei during conjugation in Paramecium caudatum." Journal of Cell Science 79, no. 1 (November 1, 1985): 237–46. http://dx.doi.org/10.1242/jcs.79.1.237.
Full textAbstract:
The survival or degeneration of nuclei produced after meiosis in Paramecium caudatum depends upon their position in the cytoplasm. The surviving nucleus lies in the paroral region, which is the region around the cytostome. In this study, this was confirmed by quantitative measurements of the location of surviving nuclei in both stained and living conjugating cells. Observation of nuclear behaviour in living cells shows that there is an active mechanism for localizing one of the four meiotic products into the paroral region after the second meiotic division. When this mechanism is inhibited by vinblastine, none of the four nuclei gets into the paroral region and all of them become pycnotic, before degenerating. The results show that migration into the paroral region is essential for survival of the nucleus and that microtubules are involved in this nuclear migration.
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Rose, A. M., P. B. Joyce, A. K. Hopper, and N. C. Martin. "Separate information required for nuclear and subnuclear localization: additional complexity in localizing an enzyme shared by mitochondria and nuclei." Molecular and Cellular Biology 12, no. 12 (December 1992): 5652–58. http://dx.doi.org/10.1128/mcb.12.12.5652-5658.1992.
Full textAbstract:
The TRM1 gene of Saccharomyces cerevisiae codes for a tRNA modification enzyme, N2,N2-dimethylguanosine-specific tRNA methyltransferase (m2(2)Gtase), shared by mitochondria and nuclei. Immunofluorescent staining at the nuclear periphery demonstrates that m2(2)Gtase localizes at or near the nuclear membrane. In determining sequences necessary for targeting the enzyme to nuclei and mitochondria, we found that information required to deliver the enzyme to the nucleus is not sufficient for its correct subnuclear localization. We also determined that mislocalizing the enzyme from the nucleus to the cytoplasm does not destroy its biological function. This change in location was caused by altering a sequence similar to other known nuclear targeting signals (KKSKKKRC), suggesting that shared enzymes are likely to use the same import pathway as proteins that localize only to the nucleus. As with other well-characterized mitochondrial proteins, the mitochondrial import of the shared methyltransferase depends on amino-terminal amino acids, and removal of the first 48 amino acids prevents its import into mitochondria. While this truncated protein is still imported into nuclei, the immunofluorescent staining is uniform throughout rather than at the nuclear periphery, a staining pattern identical to that described for a fusion protein consisting of the first 213 amino acids of m2(2)Gtase in frame with beta-galactosidase. As both of these proteins together contain the entire m2(2)Gtase coding region, the information necessary for association with the nuclear periphery must be more complex than the short linear sequence necessary for nuclear localization.