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Sample records for abnormal mitotic figures

  1. Mitotic figure counts are significantly overestimated in resection specimens of invasive breast carcinomas.

    PubMed

    Lehr, Hans-Anton; Rochat, Candice; Schaper, Cornelia; Nobile, Antoine; Shanouda, Sherien; Vijgen, Sandrine; Gauthier, Arnaud; Obermann, Ellen; Leuba, Susana; Schmidt, Marcus; C, Curzio Ruegg; Delaloye, Jean-Francois; Simiantonaki, Nectaria; Schaefer, Stephan C

    2013-03-01

    Several authors have demonstrated an increased number of mitotic figures in breast cancer resection specimen when compared with biopsy material. This has been ascribed to a sampling artifact where biopsies are (i) either too small to allow formal mitotic figure counting or (ii) not necessarily taken form the proliferating tumor periphery. Herein, we propose a different explanation for this phenomenon. Biopsy and resection material of 52 invasive ductal carcinomas was studied. We counted mitotic figures in 10 representative high power fields and quantified MIB-1 immunohistochemistry by visual estimation, counting and image analysis. We found that mitotic figures were elevated by more than three-fold on average in resection specimen over biopsy material from the same tumors (20±6 vs 6±2 mitoses per 10 high power fields, P=0.008), and that this resulted in a relative diminution of post-metaphase figures (anaphase/telophase), which made up 7% of all mitotic figures in biopsies but only 3% in resection specimen (P<0.005). At the same time, the percentages of MIB-1 immunostained tumor cells among total tumor cells were comparable in biopsy and resection material, irrespective of the mode of MIB-1 quantification. Finally, we found no association between the size of the biopsy material and the relative increase of mitotic figures in resection specimen. We propose that the increase in mitotic figures in resection specimen and the significant shift towards metaphase figures is not due to a sampling artifact, but reflects ongoing cell cycle activity in the resected tumor tissue due to fixation delay. The dwindling energy supply will eventually arrest tumor cells in metaphase, where they are readily identified by the diagnostic pathologist. Taken together, we suggest that the rapidly fixed biopsy material better represents true tumor biology and should be privileged as predictive marker of putative response to cytotoxic chemotherapy.

  2. The involvement of MCT-1 oncoprotein in inducing mitotic catastrophe and nuclear abnormalities.

    PubMed

    Shih, Hung-Ju; Chu, Kang-Lin; Wu, Meng-Hsun; Wu, Pei-Hsuan; Chang, Wei-Wen; Chu, Jan-Show; Wang, Lily Hui-Ching; Takeuchi, Hideki; Ouchi, Toru; Hsu, Hsin-Ling

    2012-03-01

    Centrosome amplification and chromosome abnormality are frequently identified in neoplasia and tumorigenesis. However, the mechanisms underlying these defects remain unclear. We here identify that MCT-1 is a centrosomal oncoprotein involved in mitosis. Knockdown of MCT-1 protein results in intercellular bridging, chromosome mis-congregation, cytokinesis delay, and mitotic death. Introduction of MCT-1 oncogene into the p53 deficient cells (MCT-1-p53), the mitotic checkpoint kinases and proteins are deregulated synergistically. These biochemical alterations are accompanied with increased frequencies of cytokinesis failure, multi-nucleation, and centrosome amplification in subsequent cell cycle. As a result, the incidences of polyploidy and aneuploidy are progressively induced by prolonged cell cultivation or further promoted by sustained spindle damage on MCT-1-p53 background. These data show that the oncoprotein perturbs centrosome structure and mitotic progression, which provide the molecular aspect of chromsomal abnormality in vitro and the information for understanding the stepwise progression of tumors under oncogenic stress.

  3. The moyamoya disease susceptibility variant RNF213 R4810K (rs112735431) induces genomic instability by mitotic abnormality

    SciTech Connect

    Hitomi, Toshiaki; Habu, Toshiyuki; Kobayashi, Hatasu; Okuda, Hiroko; Harada, Kouji H.; Osafune, Kenji; Taura, Daisuke; Sone, Masakatsu; Asaka, Isao; Ameku, Tomonaga; Watanabe, Akira; Kasahara, Tomoko; Sudo, Tomomi; Shiota, Fumihiko; Hashikata, Hirokuni; Takagi, Yasushi; Morito, Daisuke; Miyamoto, Susumu; Nakao, Kazuwa; Koizumi, Akio

    2013-10-04

    Highlights: •Overexpression of RNF213 R4810K inhibited cell proliferation. •Overexpression of RNF213 R4810K had the time of mitosis 4-fold and mitotic failure. •R4810K formed a complex with MAD2 more readily than wild-type. •iPSECs from the MMD patients had elevated mitotic failure compared from the control. •RNF213 R4810K induced mitotic abnormality and increased risk of aneuploidy. -- Abstract: Moyamoya disease (MMD) is a cerebrovascular disease characterized by occlusive lesions in the Circle of Willis. The RNF213 R4810K polymorphism increases susceptibility to MMD. In the present study, we characterized phenotypes caused by overexpression of RNF213 wild type and R4810K variant in the cell cycle to investigate the mechanism of proliferation inhibition. Overexpression of RNF213 R4810K in HeLa cells inhibited cell proliferation and extended the time of mitosis 4-fold. Ablation of spindle checkpoint by depletion of mitotic arrest deficiency 2 (MAD2) did not shorten the time of mitosis. Mitotic morphology in HeLa cells revealed that MAD2 colocalized with RNF213 R4810K. Immunoprecipitation revealed an RNF213/MAD2 complex: R4810K formed a complex with MAD2 more readily than RNF213 wild-type. Desynchronized localization of MAD2 was observed more frequently during mitosis in fibroblasts from patients (n = 3, 61.0 ± 8.2%) compared with wild-type subjects (n = 6, 13.1 ± 7.7%; p < 0.01). Aneuploidy was observed more frequently in fibroblasts (p < 0.01) and induced pluripotent stem cells (iPSCs) (p < 0.03) from patients than from wild-type subjects. Vascular endothelial cells differentiated from iPSCs (iPSECs) of patients and an unaffected carrier had a longer time from prometaphase to metaphase than those from controls (p < 0.05). iPSECs from the patients and unaffected carrier had significantly increased mitotic failure rates compared with controls (p < 0.05). Thus, RNF213 R4810K induced mitotic abnormalities and increased risk of genomic instability.

  4. Abnormal mitotic spindle assembly and cytokinesis induced by D-Limonene in cultured mammalian cells.

    PubMed

    Mauro, Maurizio; Catanzaro, Irene; Naselli, Flores; Sciandrello, Giulia; Caradonna, Fabio

    2013-11-01

    D-Limonene is found widely in citrus and many other plant species; it is a major constituent of many essential oils and is used as a solvent for commercial purposes. With the discovery of its chemotherapeutic properties against cancer, it is important to investigate the biological effects of the exposure to D-Limonene and elucidate its, as yet unknown, mechanism of action. We reported here that D-Limonene is toxic in V79 Chinese hamster cells in a dose-dependent manner. Moreover, to determine the cellular target of D-Limonene, we performed morphological observations and immunocytochemical analysis and we showed that this drug has a direct effect on dividing cells preventing assembly of mitotic spindle microtubules. This affects both chromosome segregation and cytokinesis, resulting in aneuploidy that in turn can lead to cell death or genomic instability. PMID:23913329

  5. Unequal mitotic sister chromatid exchange: A rare mechanism for chromosomal abnormality resulting in duplication/deletion of chromosome 7q

    SciTech Connect

    Eydoux, P.; Ortenberg, J.; Chalifoux, N.

    1994-09-01

    We report a case of unequal mitotic chromatid exchange, which has rarely been reported as a mechanism for microscopic chromosomal anomalies. The proposita was born at 40 weeks, after an uneventful pregnancy, of parents with a negative family history. The baby was small for gestational age and had dysmorphic features, including scaphocephaly, bilateral epicanthal folds and palpebral ptosis, mild hypertelorism, hypoplasia of orbital contours, right coloboma, bulbous prominent nose, retrognathism, downturned mouth, low set posteriorly rotated ears, tapering of the limbs. bilateral Sydney creases. At 5 months, she was under the 5th percentile for height, weight and head circumference, and had a mild developmental delay. The karyotype showed an abnormality of chromosome 7 in all cells, half with a duplication and half with a deletion of the same region; 46,XX,del(7)(q33{yields}q34)/46,XX,dup(7)(q33{yields}q34). This chromosomal abnormality could be explained by an unequal chromatid exchange occuring in the first mitosis of the embryo. To our knowledge, only one such human microscopic abnormality, involving chromosome Y, has been reported to date. This type of genetic unbalance could be missed by molecular techniques.

  6. SIRT2 knockdown increases basal autophagy and prevents postslippage death by abnormally prolonging the mitotic arrest that is induced by microtubule inhibitors.

    PubMed

    Inoue, Toshiaki; Nakayama, Yuji; Li, Yanze; Matsumori, Haruka; Takahashi, Haruka; Kojima, Hirotada; Wanibuchi, Hideki; Katoh, Motonobu; Oshimura, Mitsuo

    2014-06-01

    Mitotic catastrophe, a form of cell death that occurs during mitosis and after mitotic slippage to a tetraploid state, plays important roles in the efficacy of cancer cell killing by microtubule inhibitors (MTIs). Prolonged mitotic arrest by the spindle assembly checkpoint is a well-known requirement for mitotic catastrophe, and thus for conferring sensitivity to MTIs. We previously reported that turning off spindle assembly checkpoint activation after a defined period of time is another requirement for efficient postslippage death from a tetraploid state, and we identified SIRT2, a member of the sirtuin protein family, as a regulator of this process. Here, we investigated whether SIRT2 regulates basal autophagy and whether, in that case, autophagy regulation by SIRT2 is required for postslippage death, by analogy with previous insights into SIRT1 functions in autophagy. We show, by combined knockdown of autophagy genes and SIRT2, that SIRT2 serves this function at least partially by suppressing basal autophagy levels. Notably, increased autophagy induced by rapamycin and mild starvation caused mitotic arrest for an abnormally long period of time in the presence of MTIs, and this was followed by delayed postslippage death, which was also observed in cells with SIRT2 knockdown. These results underscore a causal association among increased autophagy levels, mitotic arrest for an abnormally long period of time after exposure to MTIs, and resistance to MTIs. Although autophagy acts as a tumor suppressor mechanism, this study highlights its negative aspects, as increased autophagy may cause mitotic catastrophe malfunction. Thus, SIRT2 offers a novel target for tumor therapy. PMID:24712640

  7. Adaptive face space coding in congenital prosopagnosia: typical figural aftereffects but abnormal identity aftereffects.

    PubMed

    Palermo, Romina; Rivolta, Davide; Wilson, C Ellie; Jeffery, Linda

    2011-12-01

    People with congenital prosopagnosia (CP) report difficulty recognising faces in everyday life and perform poorly on face recognition tests. Here, we investigate whether impaired adaptive face space coding might contribute to poor face recognition in CP. To pinpoint how adaptation may affect face processing, a group of CPs and matched controls completed two complementary face adaptation tasks: the figural aftereffect, which reflects adaptation to general distortions of shape, and the identity aftereffect, which directly taps the mechanisms involved in the discrimination of different face identities. CPs displayed a typical figural aftereffect, consistent with evidence that they are able to process some shape-based information from faces, e.g., cues to discriminate sex. CPs also demonstrated a significant identity aftereffect. However, unlike controls, CPs impression of the identity of the neutral average face was not significantly shifted by adaptation, suggesting that adaptive coding of identity is abnormal in CP. In sum, CPs show reduced aftereffects but only when the task directly taps the use of face norms used to code individual identity. This finding of a reduced face identity aftereffect in individuals with severe face recognition problems is consistent with suggestions that adaptive coding may have a functional role in face recognition.

  8. Adaptive face space coding in congenital prosopagnosia: typical figural aftereffects but abnormal identity aftereffects.

    PubMed

    Palermo, Romina; Rivolta, Davide; Wilson, C Ellie; Jeffery, Linda

    2011-12-01

    People with congenital prosopagnosia (CP) report difficulty recognising faces in everyday life and perform poorly on face recognition tests. Here, we investigate whether impaired adaptive face space coding might contribute to poor face recognition in CP. To pinpoint how adaptation may affect face processing, a group of CPs and matched controls completed two complementary face adaptation tasks: the figural aftereffect, which reflects adaptation to general distortions of shape, and the identity aftereffect, which directly taps the mechanisms involved in the discrimination of different face identities. CPs displayed a typical figural aftereffect, consistent with evidence that they are able to process some shape-based information from faces, e.g., cues to discriminate sex. CPs also demonstrated a significant identity aftereffect. However, unlike controls, CPs impression of the identity of the neutral average face was not significantly shifted by adaptation, suggesting that adaptive coding of identity is abnormal in CP. In sum, CPs show reduced aftereffects but only when the task directly taps the use of face norms used to code individual identity. This finding of a reduced face identity aftereffect in individuals with severe face recognition problems is consistent with suggestions that adaptive coding may have a functional role in face recognition. PMID:21986295

  9. Preserved local but disrupted contextual figure-ground influences in an individual with abnormal function of intermediate visual areas.

    PubMed

    Brooks, Joseph L; Gilaie-Dotan, Sharon; Rees, Geraint; Bentin, Shlomo; Driver, Jon

    2012-06-01

    Visual perception depends not only on local stimulus features but also on their relationship to the surrounding stimulus context, as evident in both local and contextual influences on figure-ground segmentation. Intermediate visual areas may play a role in such contextual influences, as we tested here by examining LG, a rare case of developmental visual agnosia. LG has no evident abnormality of brain structure and functional neuroimaging showed relatively normal V1 function, but his intermediate visual areas (V2/V3) function abnormally. We found that contextual influences on figure-ground organization were selectively disrupted in LG, while local sources of figure-ground influences were preserved. Effects of object knowledge and familiarity on figure-ground organization were also significantly diminished. Our results suggest that the mechanisms mediating contextual and familiarity influences on figure-ground organization are dissociable from those mediating local influences on figure-ground assignment. The disruption of contextual processing in intermediate visual areas may play a role in the substantial object recognition difficulties experienced by LG.

  10. Diagnostic cellular abnormalities in neoplastic and non-neoplastic lesions of the epidermis: a morphological and statistical study

    PubMed Central

    Malhotra, Saurabh; Kazlouskaya, Viktoryia; Andres, Christian; Gui, Jiang; Elston, Dirk

    2013-01-01

    Background Distinguishing cellular abnormalities in reactive and malignant lesions is challenging. We compared the incidence and severity of cytological abnormalities in malignant/premalignant and benign epidermal lesions. Methods One hundred fifty-two biopsies representing 69 malignant/premalignant squamous lesions and 83 benign conditions were studied. Cytological features, including nuclear hyperchromasia, nuclear overlap (crowding), irregular nuclei, high nuclear/cytoplasmic (N/C) ratio, conspicuous nucleoli, delicate inconspicuous nucleoli, clumped chromatin, pleomorphic parakeratosis, normal and abnormal mitotic figures and necrotic keratinocytes, were evaluated and graded. Statistical analysis was performed. Results Irregular nuclei, increased N/C ratio, conspicuous single prominent nucleoli, nuclear overlap (crowding), pleomorphic parakeratosis, nuclear hyperchromasia, necrotic keratinocytes, normal and abnormal mitotic figures and coarse chromatin were seen more frequently in malignant neoplasms (p < 0.05). Abnormal mitotic figures, although uncommon (20.3%), were only noted in the malignant/premalignant group. Certain cytological features were common among both malignant and benign lesions, suggesting that they are of little value. Conclusion In the setting of an atypical cutaneous squamous proliferation, nuclear irregularity, increased N/C ratio, conspicuous nucleoli, crowding and hyperchromasia are the most useful indicators of malignancy. In contrast, mitotic figures, necrotic cells and coarse chromatin are less useful. The presence of abnormal mitotic figures is very helpful when present; however, their overall rarity limits their utility. PMID:23398548

  11. Defective control of mitotic and post-mitotic checkpoints in poly(ADP-ribose) polymerase-1(-/-) fibroblasts after mitotic spindle disruption.

    PubMed

    Halappanavar, Sabina S; Shah, Girish M

    2004-03-01

    Poly(ADP-ribose) polymerase-1 (PARP), a DNA damage-responsive nuclear enzyme present in higher eukaryotes, is well-known for its roles in protecting the genome after DNA damage. However, even without exogenous DNA damage, PARP may play a role in stabilizing the genome because cells or mice deficient in PARP exhibit various signs of genomic instability, such as tetraploidy, aneuploidy, chromosomal abnormalities and susceptibility to spontaneous carcinogenesis. Normally, cell cycle checkpoints ensure elimination of cells with genomic abnormalities. Therefore, we examined efficiency of mitotic and post-mitotic checkpoints in PARP-/- and PARP+/+ mouse embryonic fibroblasts treated with mitotic spindle disrupting agent colcemid. PARP+/+ cells, like most mammalian cells, eventually escaped from spindle disruption-induced mitotic checkpoint arrest by 60 h. In contrast, PARP-/- cells rapidly escaped from mitotic arrest within 24 h by downregulation of cyclin B1/CDK-1 kinase activity. After escaping from mitotic arrest; both the PARP genotypes arrive in G1 tetraploid state, where they face post-mitotic checkpoints which either induce apoptosis or prevent DNA endoreduplication. While all the G1 tetraploid PARP+/+ cells were eliminated by apoptosis, the majority of the G1 tetraploid PARP-/- cells became polyploid by resisting apoptosis and carrying out DNA endoreduplication. Introduction of PARP in PARP-/- fibroblasts partially increased the stringency of mitotic checkpoint arrest and fully restored susceptibility to G1 tetraploidy checkpoint-induced apoptosis; and thus prevented formation of polyploid cells. Our results suggest that PARP may serve as a guardian angel of the genome even without exogenous DNA damage through its role in mitotic and post-mitotic G1 tetraploidy checkpoints. PMID:14726664

  12. Mitotic Index is an Independent Predictor of Recurrence-Free Survival in Meningioma.

    PubMed

    Olar, Adriana; Wani, Khalida M; Sulman, Erik P; Mansouri, Alireza; Zadeh, Gelareh; Wilson, Charmaine D; DeMonte, Franco; Fuller, Gregory N; Aldape, Kenneth D

    2015-05-01

    While World Health Organization (WHO) grading of meningioma stratifies patients according to recurrence risk overall, there is substantial within-grade heterogeneity with respect to recurrence-free survival (RFS). Most meningiomas are graded according to mitotic counts per unit area on hematoxylin and eosin sections, a method potentially confounded by tumor cellularity, as well as potential limitations of accurate mitotic figure detection on routine histology. To refine mitotic figure assessment, we evaluated 363 meningiomas with phospho-histone H3 (Ser10) and determined the mitotic index (number of mitoses per 1000 tumor cells). The median mitotic indices among WHO grade I (n = 268), grade II (n = 84) and grade III (n = 11) tumors were 1, 4 and 12. Classification and regression tree analysis to categorize cut-offs identified three subgroups defined by mitotic indices of 0-2, 3-4 and ≥5, which on univariate analysis were associated with RFS (P < 0.01). In multivariate analysis, mitotic index subgrouped in this manner was significantly associated with RFS (P < 0.01) after adjustment for Simpson grade, WHO grade and MIB-1 index. Mitotic index was then examined within individual WHO grade, showing that for grade I and grade II meningiomas, mitotic index can add additional information to RFS risk. The results suggest that the use of a robust mitotic marker in meningioma could refine risk stratification. PMID:25040885

  13. Go Figure.

    ERIC Educational Resources Information Center

    Greenman, Geri

    2000-01-01

    Describes the first assignment for an intermediate oil painting class in which the students painted the human figure. Explains that the assignment involved three techniques: (1) abstract application of acrylic paint; (2) oil "Paintstiks" from Shiva; and (3) a final layer of actual oil paint. (CMK)

  14. Mitotic Spindle Disruption by Alternating Electric Fields Leads to Improper Chromosome Segregation and Mitotic Catastrophe in Cancer Cells

    PubMed Central

    Giladi, Moshe; Schneiderman, Rosa S; Voloshin, Tali; Porat, Yaara; Munster, Mijal; Blat, Roni; Sherbo, Shay; Bomzon, Zeev; Urman, Noa; Itzhaki, Aviran; Cahal, Shay; Shteingauz, Anna; Chaudhry, Aafia; Kirson, Eilon D; Weinberg, Uri; Palti, Yoram

    2015-01-01

    Tumor Treating Fields (TTFields) are low intensity, intermediate frequency, alternating electric fields. TTFields are a unique anti-mitotic treatment modality delivered in a continuous, noninvasive manner to the region of a tumor. It was previously postulated that by exerting directional forces on highly polar intracellular elements during mitosis, TTFields could disrupt the normal assembly of spindle microtubules. However there is limited evidence directly linking TTFields to an effect on microtubules. Here we report that TTFields decrease the ratio between polymerized and total tubulin, and prevent proper mitotic spindle assembly. The aberrant mitotic events induced by TTFields lead to abnormal chromosome segregation, cellular multinucleation, and caspase dependent apoptosis of daughter cells. The effect of TTFields on cell viability and clonogenic survival substantially depends upon the cell division rate. We show that by extending the duration of exposure to TTFields, slowly dividing cells can be affected to a similar extent as rapidly dividing cells. PMID:26658786

  15. Mitotic Spindle Disruption by Alternating Electric Fields Leads to Improper Chromosome Segregation and Mitotic Catastrophe in Cancer Cells.

    PubMed

    Giladi, Moshe; Schneiderman, Rosa S; Voloshin, Tali; Porat, Yaara; Munster, Mijal; Blat, Roni; Sherbo, Shay; Bomzon, Zeev; Urman, Noa; Itzhaki, Aviran; Cahal, Shay; Shteingauz, Anna; Chaudhry, Aafia; Kirson, Eilon D; Weinberg, Uri; Palti, Yoram

    2015-01-01

    Tumor Treating Fields (TTFields) are low intensity, intermediate frequency, alternating electric fields. TTFields are a unique anti-mitotic treatment modality delivered in a continuous, noninvasive manner to the region of a tumor. It was previously postulated that by exerting directional forces on highly polar intracellular elements during mitosis, TTFields could disrupt the normal assembly of spindle microtubules. However there is limited evidence directly linking TTFields to an effect on microtubules. Here we report that TTFields decrease the ratio between polymerized and total tubulin, and prevent proper mitotic spindle assembly. The aberrant mitotic events induced by TTFields lead to abnormal chromosome segregation, cellular multinucleation, and caspase dependent apoptosis of daughter cells. The effect of TTFields on cell viability and clonogenic survival substantially depends upon the cell division rate. We show that by extending the duration of exposure to TTFields, slowly dividing cells can be affected to a similar extent as rapidly dividing cells. PMID:26658786

  16. Mitotic chromosome structure and condensation.

    PubMed

    Belmont, Andrew S

    2006-12-01

    Mitotic chromosome structure has been the cell biology equivalent of a 'riddle, wrapped in a mystery, inside an enigma'. Observations that genetic knockout or knockdown of condensin subunits or topoisomerase II cause only minimal perturbation in overall chromosome condensation, together with analysis of early stages of chromosome condensation and effects produced by histone H1 depletion, suggest a need to reconsider textbook models of mitotic chromosome condensation and organization. PMID:17046228

  17. Variation in sensitivity to. gamma. -ray-induced chromosomal aberrations during the mitotic cycle of the sea urchin egg

    SciTech Connect

    Ejima, Y.; Nakamura, I.; Shiroya, T.

    1982-11-01

    Sea urchin eggs were irradiated with /sup 137/Cs ..gamma.. rays at various stages of the mitotic cycle, and chromosomal aberrations at the first postirradiation mitosis and embryonic abnormalities at later developmental stages were examined. The radiosensitivity of the eggs to both endpoints varied in parallel with the mitotic stage at the time of irradiation, suggesting a possible relationship between chromosomal damage and embryonic abnormalities.

  18. Gamma-actin is involved in regulating centrosome function and mitotic progression in cancer cells.

    PubMed

    Po'uha, Sela T; Kavallaris, Maria

    2015-01-01

    Reorganization of the actin cytoskeleton during mitosis is crucial for regulating cell division. A functional role for γ-actin in mitotic arrest induced by the microtubule-targeted agent, paclitaxel, has recently been demonstrated. We hypothesized that γ-actin plays a role in mitosis. Herein, we investigated the effect of γ-actin in mitosis and demonstrated that γ-actin is important in the distribution of β-actin and formation of actin-rich retraction fibers during mitosis. The reduced ability of paclitaxel to induce mitotic arrest as a result of γ-actin depletion was replicated with a range of mitotic inhibitors, suggesting that γ-actin loss reduces the ability of broad classes of anti-mitotic agents to induce mitotic arrest. In addition, partial depletion of γ-actin enhanced centrosome amplification in cancer cells and caused a significant delay in prometaphase/metaphase. This prolonged prometaphase/metaphase arrest was due to mitotic defects such as uncongressed and missegregated chromosomes, and correlated with an increased presence of mitotic spindle abnormalities in the γ-actin depleted cells. Collectively, these results demonstrate a previously unknown role for γ-actin in regulating centrosome function, chromosome alignment and maintenance of mitotic spindle integrity.

  19. Micromechanics of human mitotic chromosomes

    NASA Astrophysics Data System (ADS)

    Sun, Mingxuan; Kawamura, Ryo; Marko, John F.

    2011-02-01

    Eukaryote cells dramatically reorganize their long chromosomal DNAs to facilitate their physical segregation during mitosis. The internal organization of folded mitotic chromosomes remains a basic mystery of cell biology; its understanding would likely shed light on how chromosomes are separated from one another as well as into chromosome structure between cell divisions. We report biophysical experiments on single mitotic chromosomes from human cells, where we combine micromanipulation, nano-Newton-scale force measurement and biochemical treatments to study chromosome connectivity and topology. Results are in accord with previous experiments on amphibian chromosomes and support the 'chromatin network' model of mitotic chromosome structure. Prospects for studies of chromosome-organizing proteins using siRNA expression knockdowns, as well as for differential studies of chromosomes with and without mutations associated with genetic diseases, are also discussed.

  20. Theory of Mitotic Spindle Oscillations

    NASA Astrophysics Data System (ADS)

    Grill, Stephan W.; Kruse, Karsten; Jülicher, Frank

    2005-03-01

    During unequal cell division the mitotic spindle is positioned away from the center of the cell before cell cleavage. In many biological systems this repositioning is accompanied by oscillatory movements of the spindle. We present a theoretical description for mitotic spindle oscillations. We show that the cooperative attachment and detachment of cortical force generators to astral microtubules leads to spontaneous oscillations beyond a critical number of force generators. This mechanism can quantitatively describe the spindle oscillations observed during unequal division of the one cell stage Caenorhabditis elegans embryo.

  1. SIAH-1 inhibits cell growth by altering the mitotic process.

    PubMed

    Bruzzoni-Giovanelli, H; Faille, A; Linares-Cruz, G; Nemani, M; Le Deist, F; Germani, A; Chassoux, D; Millot, G; Roperch, J P; Amson, R; Telerman, A; Calvo, F

    1999-11-25

    SIAH-1, the human homologue of the drosophila seven in absentia gene, is a p53-p21Waf-1 inducible gene. We report that stable transfection with SIAH-1 of the epithelial breast cancer cell line MCF-7 blocks its growth process. The transfectants show a redistribution of SIAH-1 protein within the nucleus, more specifically to the nuclear matrix, associated to dramatic changes in cell morphology and defective mitosis. Multinucleated giant cells (2-12 nuclei in more than 50% cells) were a most striking observation associated with tubulin spindle disorganization and defective cytokinesis. There were also present at high frequency abortive mitotic figures, DNA bridges and persistance of intercellular bridges and midbodies, along with an increased expression of p21Waf-1. These results indicate that the mechanism of growth arrest induced by SIAH-1 in MCF-7 cells involves disorganization of the mitotic program, mainly during nuclei separation and cytokinesis.

  2. All about Lissajous Figures.

    ERIC Educational Resources Information Center

    Greenslade, Thomas B.

    1993-01-01

    Uses diagrams and text to illustrate the use of Lissajous figures (the figures that are traced out when two simple harmonic motions are combined at right angles to each other) in teaching basic physics concepts. Covers the mathematics of the Lissajous Figure; demonstrating Lissajous Figures; and a typical class. (ZWH)

  3. Arsenite-induced mitotic death involves stress response and is independent of tubulin polymerization

    SciTech Connect

    Taylor, B. Frazier; McNeely, Samuel C.; Miller, Heather L.; States, J. Christopher

    2008-07-15

    Arsenite, a known mitotic disruptor, causes cell cycle arrest and cell death at anaphase. The mechanism causing mitotic arrest is highly disputed. We compared arsenite to the spindle poisons nocodazole and paclitaxel. Immunofluorescence analysis of {alpha}-tubulin in interphase cells demonstrated that, while nocodazole and paclitaxel disrupt microtubule polymerization through destabilization and hyperpolymerization, respectively, microtubules in arsenite-treated cells remain comparable to untreated cells even at supra-therapeutic concentrations. Immunofluorescence analysis of {alpha}-tubulin in mitotic cells showed spindle formation in arsenite- and paclitaxel-treated cells but not in nocodazole-treated cells. Spindle formation in arsenite-treated cells appeared irregular and multi-polar. {gamma}-tubulin staining showed that cells treated with nocodazole and therapeutic concentrations of paclitaxel contained two centrosomes. In contrast, most arsenite-treated mitotic cells contained more than two centrosomes, similar to centrosome abnormalities induced by heat shock. Of the three drugs tested, only arsenite treatment increased expression of the inducible isoform of heat shock protein 70 (HSP70i). HSP70 and HSP90 proteins are intimately involved in centrosome regulation and mitotic spindle formation. HSP90 inhibitor 17-DMAG sensitized cells to arsenite treatment and increased arsenite-induced centrosome abnormalities. Combined treatment of 17-DMAG and arsenite resulted in a supra-additive effect on viability, mitotic arrest, and centrosome abnormalities. Thus, arsenite-induced abnormal centrosome amplification and subsequent mitotic arrest is independent of effects on tubulin polymerization and may be due to specific stresses that are protected against by HSP90 and HSP70.

  4. Chromosomal abnormalities associated with cyclopia and synophthalmia.

    PubMed Central

    Howard, R O

    1977-01-01

    At the present time, essentially all known facts concerning cyclopia are consistent with some chromosomal disease, including clinical features of the pregnancy (fetal wastage, prematurity, intrauterine growth retardation, maternal age factor, complications of pregnancy), the generalized developmental abnormalities, specific ocular dysgenesis, by the high incidence of chromosomal abnormality already demonstrated, and the possibility of error in those cases of cyclopia with normal chromosomes. Even if chromosomal aberrations represent only one group of several different etiologic factors leading to cyclopia, at the present time chromosomal errors would seem to be the most common cause of cyclopia now recognized. Further studies will establish or disprove a chromosomal error in those instances which are now considered to be the result of an environmental factor alone or those with apparent familial patterns of inheritance. This apparent diverse origin of cyclopia can be clarified if future cyclopic specimens are carefully investigated. The evaluation should include a careful gross and microscopic examination of all organs, including the eye, and chromosome banding studies of all organs, including the eye, and chromosome banding studies of at least two cyclopic tissues. Then the presence or absence of multiple causative factors can be better evaluated. Images FIGURE 2 A FIGURE 2 B FIGURE 1 A FIGURE 1 B FIGURE 1 C FIGURE 1 D FIGURE 1 E FIGURE 1 F FIGURE 3 A FIGURE 3 B FIGURE 4 A FIGURE 4 B FIGURE 4 C FIGURE 4 D FIGURE 5 FIGURE 6 FIGURE 7 A FIGURE 7 B PMID:418547

  5. p53 activates G₁ checkpoint following DNA damage by doxorubicin during transient mitotic arrest.

    PubMed

    Hyun, Sun-Yi; Jang, Young-Joo

    2015-03-10

    Recovery from DNA damage is critical for cell survival. The serious damage is not able to be repaired during checkpoint and finally induces cell death to prevent abnormal cell growth. In this study, we demonstrated that 8N-DNA contents are accumulated via re-replication during prolonged recovery period containing serious DNA damage in mitotic cells. During the incubation for recovery, a mitotic delay and initiation of an abnormal interphase without cytokinesis were detected. Whereas a failure of cytokinesis occurred in cells with no relation with p53/p21, re-replication is an anomalous phenomenon in the mitotic DNA damage response in p53/p21 negative cells. Cells with wild-type p53 are accumulated just prior to the initiation of DNA replication through a G₁ checkpoint after mitotic DNA damage, even though p53 does not interrupt pre-RC assembly. Finally, these cells undergo cell death by apoptosis. These data suggest that p53 activates G₁ checkpoint in response to mitotic DNA damage. Without p53, cells with mitotic DNA damage undergo re-replication leading to accumulation of damage.

  6. The influence of fixation delay on mitotic activity and flow cytometric cell cycle variables.

    PubMed

    Bergers, E; Jannink, I; van Diest, P I; Cuesta, M A; Meyer, S; van Mourik, J C; Baak, J P

    1997-01-01

    Proliferation variables such as mitotic activity and the percentage of S-phase cells have been shown to be of prognostic value in many tumors, especially in breast cancer. However, some studies reported a decrease in mitotic activity caused by delay in fixation of the tissue. In contrast, other studies showed that the identifiability of mitotic figures decreases after fixation delay, but the total number of mitotic figures and also the percentage of S-phase cells remain unchanged. Most studies have been done on small numbers of experimental tumors, thus introducing the risk of selection bias. The aim of this study was to reinvestigate the influence of fixation delay on mitotic activity and cell cycle variables assessed by flow cytometry in an adequate number of resected human tissues to reach firmer conclusions. Resection specimens of 19 and 21 cases, respectively, for the mitotic activity estimate and the flow cytometric percentage of S-phase calculation were collected directly from the operating theater using lung, breast, and intestinal cancers and normal intestinal mucosa. The tissues were cut in pieces, and from each specimen, pieces were fixed in 4% buffered formaldehyde (for mitosis counting) as well as snap frozen (for flow cytometry) immediately after excision, as well as after a fixation delay of 1, 2, 4, 6, 8, 18, and 24 hours. Moreover, during the fixation delay, one series from each specimen was kept in the refrigerator and the second at room temperature. Thus, a total of 304 (19 X 16) and 336 (21 X 16) specimens were investigated for the mitotic activity estimate and the percentage of S-phase cells calculation, respectively. With regard to the estimation of the mitotic activity, both clear and doubtful mitotic figures were registered separately, obtaining an "uncorrected" and "corrected" (for doubtful mitotic figures) mitotic activity estimate. The percentage of S-phase cells was obtained by cell cycle analysis of flow cytometric DNA-histograms. The

  7. Adenovirus Replaces Mitotic Checkpoint Controls

    PubMed Central

    Turner, Roberta L.; Groitl, Peter; Dobner, Thomas

    2015-01-01

    ABSTRACT Infection with adenovirus triggers the cellular DNA damage response, elements of which include cell death and cell cycle arrest. Early adenoviral proteins, including the E1B-55K and E4orf3 proteins, inhibit signaling in response to DNA damage. A fraction of cells infected with an adenovirus mutant unable to express the E1B-55K and E4orf3 genes appeared to arrest in a mitotic-like state. Cells infected early in G1 of the cell cycle were predisposed to arrest in this state at late times of infection. This arrested state, which displays hallmarks of mitotic catastrophe, was prevented by expression of either the E1B-55K or the E4orf3 genes. However, E1B-55K mutant virus-infected cells became trapped in a mitotic-like state in the presence of the microtubule poison colcemid, suggesting that the two viral proteins restrict entry into mitosis or facilitate exit from mitosis in order to prevent infected cells from arresting in mitosis. The E1B-55K protein appeared to prevent inappropriate entry into mitosis through its interaction with the cellular tumor suppressor protein p53. The E4orf3 protein facilitated exit from mitosis by possibly mislocalizing and functionally inactivating cyclin B1. When expressed in noninfected cells, E4orf3 overcame the mitotic arrest caused by the degradation-resistant R42A cyclin B1 variant. IMPORTANCE Cells that are infected with adenovirus type 5 early in G1 of the cell cycle are predisposed to arrest in a mitotic-like state in a p53-dependent manner. The adenoviral E1B-55K protein prevents entry into mitosis. This newly described activity for the E1B-55K protein appears to depend on the interaction between the E1B-55K protein and the tumor suppressor p53. The adenoviral E4orf3 protein facilitates exit from mitosis, possibly by altering the intracellular distribution of cyclin B1. By preventing entry into mitosis and by promoting exit from mitosis, these adenoviral proteins act to prevent the infected cell from arresting in a

  8. Microcephaly disease gene Wdr62 regulates mitotic progression of embryonic neural stem cells and brain size.

    PubMed

    Chen, Jian-Fu; Zhang, Ying; Wilde, Jonathan; Hansen, Kirk C; Lai, Fan; Niswander, Lee

    2014-05-30

    Human genetic studies have established a link between a class of centrosome proteins and microcephaly. Current studies of microcephaly focus on defective centrosome/spindle orientation. Mutations in WDR62 are associated with microcephaly and other cortical abnormalities in humans. Here we create a mouse model of Wdr62 deficiency and find that the mice exhibit reduced brain size due to decreased neural progenitor cells (NPCs). Wdr62 depleted cells show spindle instability, spindle assembly checkpoint (SAC) activation, mitotic arrest and cell death. Mechanistically, Wdr62 associates and genetically interacts with Aurora A to regulate spindle formation, mitotic progression and brain size. Our results suggest that Wdr62 interacts with Aurora A to control mitotic progression, and loss of these interactions leads to mitotic delay and cell death of NPCs, which could be a potential cause of human microcephaly.

  9. Mechanisms of Mitotic Spindle Assembly

    PubMed Central

    Petry, Sabine

    2016-01-01

    Life depends on cell proliferation and the accurate segregation of chromosomes, which are mediated by the microtubule (MT)-based mitotic spindle and ~200 essential MT-associated proteins. Yet, a mechanistic understanding of how the mitotic spindle is assembled and achieves chromosome segregation is still missing. This is mostly due to the density of MTs in the spindle, which presumably precludes their direct observation. Recent insight has been gained into the molecular building plan of the metaphase spindle using bulk and single-molecule measurements combined with computational modeling. MT nucleation was uncovered as a key principle of spindle assembly, and mechanistic details about MT nucleation pathways and their coordination are starting to be revealed. Lastly, advances in studying spindle assembly can be applied to address the molecular mechanisms of how the spindle segregates chromosomes. PMID:27145846

  10. Suppression of ectopic assembly of centriole proteins ensures mitotic spindle integrity.

    PubMed

    Shiratsuchi, Gen; Kitagawa, Daiju

    2015-01-01

    Abnormalities in maintaining the appropriate number of centrioles could be the origin of genome instability in tumor formation. Recently, we demonstrated that ectopic formation of aberrant centriole-related structures occurs even in the presence of pre-existing centrioles, leading to mitotic spindle defects and possibly contributing to tumorigenesis. PMID:27308496

  11. Axin localizes to mitotic spindles and centrosomes in mitotic cells

    SciTech Connect

    Kim, Shi-Mun; Choi, Eun-Jin; Song, Ki-Joon; Kim, Sewoon; Seo, Eunjeong; Jho, Eek-Hoon; Kee, Sun-Ho

    2009-04-01

    Wnt signaling plays critical roles in cell proliferation and carcinogenesis. In addition, numerous recent studies have shown that various Wnt signaling components are involved in mitosis and chromosomal instability. However, the role of Axin, a negative regulator of Wnt signaling, in mitosis has remained unclear. Using monoclonal antibodies against Axin, we found that Axin localizes to the centrosome and along mitotic spindles. This localization was suppressed by siRNA specific for Aurora A kinase and by Aurora kinase inhibitor. Interestingly, Axin over-expression altered the subcellular distribution of Plk1 and of phosphorylated glycogen synthase kinase (GSK3{beta}) without producing any notable changes in cellular phenotype. In the presence of Aurora kinase inhibitor, Axin over-expression induced the formation of cleavage furrow-like structures and of prominent astral microtubules lacking midbody formation in a subset of cells. Our results suggest that Axin modulates distribution of Axin-associated proteins such as Plk1 and GSK3{beta} in an expression level-dependent manner and these interactions affect the mitotic process, including cytokinesis under certain conditions, such as in the presence of Aurora kinase inhibitor.

  12. Microelasticity of Single Mitotic Chromosomes

    NASA Astrophysics Data System (ADS)

    Poirier, Michael; Eroglu, Sertac; Chatenay, Didier; Marko, John F.; Hirano, Tatsuya

    2000-03-01

    The force-extension behavior of mitotic chromosomes from the newt TVI tumor cell line was studied using micropipette manipulation and force measuring techniques. Reversible, linear elastic response was observed for extensions up to 5 times the native length; the force required to double chromosome length was 1 nanonewton (nN). For further elongations, the linear response teminates at a force plateau of 15 nN and at an extension of 20x. Beyond this extension, the chromosome breaks at elongations between 20x and 70x. These results will be compared to the similar behavior of mitotic chromosomes from explanted newt cells (Poirier, Eroglu, Chatenay and Marko, Mol. Biol. Cell, in press). Also, the effect of biochemical modifications on the elasticity was studied. Ethidium Bromide, which binds to DNA, induces up to a 10 times increase in the Young's modulus. Anti-XCAP-E, which binds to a putative chromosome folding protein, induces up to a 2 times increase in the Young's modulus. Preliminary results on the dynamical relaxation of chromosomes will also be presented. Support of this research through a Biomedical Engineering Research Grant from The Whitaker Foundation is gratefully acknowledged.

  13. OTSSP167 Abrogates Mitotic Checkpoint through Inhibiting Multiple Mitotic Kinases

    PubMed Central

    Tipton, Aaron R.; Bekier, Michael E.; Taylor, William R.; Yen, Tim J.; Liu, Song-Tao

    2016-01-01

    OTSSP167 was recently characterized as a potent inhibitor for maternal embryonic leucine zipper kinase (MELK) and is currently tested in Phase I clinical trials for solid tumors that have not responded to other treatment. Here we report that OTSSP167 abrogates the mitotic checkpoint at concentrations used to inhibit MELK. The abrogation is not recapitulated by RNAi mediated silencing of MELK in cells. Although OTSSP167 indeed inhibits MELK, it exhibits off-target activity against Aurora B kinase in vitro and in cells. Furthermore, OTSSP167 inhibits BUB1 and Haspin kinases, reducing phosphorylation at histones H2AT120 and H3T3 and causing mislocalization of Aurora B and associated chromosomal passenger complex from the centromere/kinetochore. The results suggest that OTSSP167 may have additional mechanisms of action for cancer cell killing and caution the use of OTSSP167 as a MELK specific kinase inhibitor in biochemical and cellular assays. PMID:27082996

  14. OTSSP167 Abrogates Mitotic Checkpoint through Inhibiting Multiple Mitotic Kinases.

    PubMed

    Ji, Wenbin; Arnst, Christopher; Tipton, Aaron R; Bekier, Michael E; Taylor, William R; Yen, Tim J; Liu, Song-Tao

    2016-01-01

    OTSSP167 was recently characterized as a potent inhibitor for maternal embryonic leucine zipper kinase (MELK) and is currently tested in Phase I clinical trials for solid tumors that have not responded to other treatment. Here we report that OTSSP167 abrogates the mitotic checkpoint at concentrations used to inhibit MELK. The abrogation is not recapitulated by RNAi mediated silencing of MELK in cells. Although OTSSP167 indeed inhibits MELK, it exhibits off-target activity against Aurora B kinase in vitro and in cells. Furthermore, OTSSP167 inhibits BUB1 and Haspin kinases, reducing phosphorylation at histones H2AT120 and H3T3 and causing mislocalization of Aurora B and associated chromosomal passenger complex from the centromere/kinetochore. The results suggest that OTSSP167 may have additional mechanisms of action for cancer cell killing and caution the use of OTSSP167 as a MELK specific kinase inhibitor in biochemical and cellular assays. PMID:27082996

  15. Mitotic chromosome condensation in vertebrates

    SciTech Connect

    Vagnarelli, Paola

    2012-07-15

    Work from several laboratories over the past 10-15 years has revealed that, within the interphase nucleus, chromosomes are organized into spatially distinct territories [T. Cremer, C. Cremer, Chromosome territories, nuclear architecture and gene regulation in mammalian cells, Nat. Rev. Genet. 2 (2001) 292-301 and T. Cremer, M. Cremer, S. Dietzel, S. Muller, I. Solovei, S. Fakan, Chromosome territories-a functional nuclear landscape, Curr. Opin. Cell Biol. 18 (2006) 307-316]. The overall compaction level and intranuclear location varies as a function of gene density for both entire chromosomes [J.A. Croft, J.M. Bridger, S. Boyle, P. Perry, P. Teague,W.A. Bickmore, Differences in the localization and morphology of chromosomes in the human nucleus, J. Cell Biol. 145 (1999) 1119-1131] and specific chromosomal regions [N.L. Mahy, P.E. Perry, S. Gilchrist, R.A. Baldock, W.A. Bickmore, Spatial organization of active and inactive genes and noncoding DNA within chromosome territories, J. Cell Biol. 157 (2002) 579-589] (Fig. 1A, A'). In prophase, when cyclin B activity reaches a high threshold, chromosome condensation occurs followed by Nuclear Envelope Breakdown (NEB) [1]. At this point vertebrate chromosomes appear as compact structures harboring an attachment point for the spindle microtubules physically recognizable as a primary constriction where the two sister chromatids are held together. The transition from an unshaped interphase chromosome to the highly structured mitotic chromosome (compare Figs. 1A and B) has fascinated researchers for several decades now; however a definite picture of how this process is achieved and regulated is not yet in our hands and it will require more investigation to comprehend the complete process. From a biochemical point of view a vertebrate mitotic chromosomes is composed of DNA, histone proteins (60%) and non-histone proteins (40%) [6]. I will discuss below what is known to date on the contribution of these two different classes of

  16. BRCA1 interaction of centrosomal protein Nlp is required for successful mitotic progression.

    PubMed

    Jin, Shunqian; Gao, Hua; Mazzacurati, Lucia; Wang, Yang; Fan, Wenhong; Chen, Qiang; Yu, Wei; Wang, Mingrong; Zhu, Xueliang; Zhang, Chuanmao; Zhan, Qimin

    2009-08-21

    Breast cancer susceptibility gene BRCA1 is implicated in the control of mitotic progression, although the underlying mechanism(s) remains to be further defined. Deficiency of BRCA1 function leads to disrupted mitotic machinery and genomic instability. Here, we show that BRCA1 physically interacts and colocalizes with Nlp, an important molecule involved in centrosome maturation and spindle formation. Interestingly, Nlp centrosomal localization and its protein stability are regulated by normal cellular BRCA1 function because cells containing BRCA1 mutations or silenced for endogenous BRCA1 exhibit disrupted Nlp colocalization to centrosomes and enhanced Nlp degradation. Its is likely that the BRCA1 regulation of Nlp stability involves Plk1 suppression. Inhibition of endogenous Nlp via the small interfering RNA approach results in aberrant spindle formation, aborted chromosomal segregation, and aneuploidy, which mimic the phenotypes of disrupted BRCA1. Thus, BRCA1 interaction of Nlp might be required for the successful mitotic progression, and abnormalities of Nlp lead to genomic instability.

  17. Mitotic Stress Is an Integral Part of the Oncogene-Induced Senescence Program that Promotes Multinucleation and Cell Cycle Arrest.

    PubMed

    Dikovskaya, Dina; Cole, John J; Mason, Susan M; Nixon, Colin; Karim, Saadia A; McGarry, Lynn; Clark, William; Hewitt, Rachael N; Sammons, Morgan A; Zhu, Jiajun; Athineos, Dimitris; Leach, Joshua D G; Marchesi, Francesco; van Tuyn, John; Tait, Stephen W; Brock, Claire; Morton, Jennifer P; Wu, Hong; Berger, Shelley L; Blyth, Karen; Adams, Peter D

    2015-09-01

    Oncogene-induced senescence (OIS) is a tumor suppression mechanism that blocks cell proliferation in response to oncogenic signaling. OIS is frequently accompanied by multinucleation; however, the origin of this is unknown. Here, we show that multinucleate OIS cells originate mostly from failed mitosis. Prior to senescence, mutant H-RasV12 activation in primary human fibroblasts compromised mitosis, concordant with abnormal expression of mitotic genes functionally linked to the observed mitotic spindle and chromatin defects. Simultaneously, H-RasV12 activation enhanced survival of cells with damaged mitoses, culminating in extended mitotic arrest and aberrant exit from mitosis via mitotic slippage. ERK-dependent transcriptional upregulation of Mcl1 was, at least in part, responsible for enhanced survival and slippage of cells with mitotic defects. Importantly, mitotic slippage and oncogene signaling cooperatively induced senescence and key senescence effectors p21 and p16. In summary, activated Ras coordinately triggers mitotic disruption and enhanced cell survival to promote formation of multinucleate senescent cells. PMID:26299965

  18. A mitotic kinase scaffold depleted in testicular seminomas impacts spindle orientation in germ line stem cells.

    PubMed

    Hehnly, Heidi; Canton, David; Bucko, Paula; Langeberg, Lorene K; Ogier, Leah; Gelman, Irwin; Santana, L Fernando; Wordeman, Linda; Scott, John D

    2015-09-25

    Correct orientation of the mitotic spindle in stem cells underlies organogenesis. Spindle abnormalities correlate with cancer progression in germ line-derived tumors. We discover a macromolecular complex between the scaffolding protein Gravin/AKAP12 and the mitotic kinases, Aurora A and Plk1, that is down regulated in human seminoma. Depletion of Gravin correlates with an increased mitotic index and disorganization of seminiferous tubules. Biochemical, super-resolution imaging, and enzymology approaches establish that this Gravin scaffold accumulates at the mother spindle pole during metaphase. Manipulating elements of the Gravin-Aurora A-Plk1 axis prompts mitotic delay and prevents appropriate assembly of astral microtubules to promote spindle misorientation. These pathological responses are conserved in seminiferous tubules from Gravin(-/-) mice where an overabundance of Oct3/4 positive germ line stem cells displays randomized orientation of mitotic spindles. Thus, we propose that Gravin-mediated recruitment of Aurora A and Plk1 to the mother (oldest) spindle pole contributes to the fidelity of symmetric cell division.

  19. Meiotic double-strand breaks uncover and protect against mitotic errors in the C. elegans germline.

    PubMed

    Stevens, Deanna; Oegema, Karen; Desai, Arshad

    2013-12-01

    In sexually reproducing multicellular organisms, genetic information is propagated via the germline, the specialized tissue that generates haploid gametes. The C. elegans germline generates gametes in an assembly line-like process-mitotic divisions under the control of the stem cell niche produce nuclei that, upon leaving the niche, enter into meiosis and progress through meiotic prophase [1]. Here, we characterize the effects of perturbing cell division in the mitotic region of the C. elegans germline. We show that mitotic errors result in a spindle checkpoint-dependent cell-cycle delay, but defective nuclei are eventually formed and enter meiosis. These defective nuclei are eliminated by programmed cell death during meiotic prophase. The cell death-based removal of defective nuclei does not require the spindle checkpoint but instead depends on the DNA damage checkpoint. Removal of nuclei resulting from errors in mitosis also requires Spo11, the enzyme that creates double-strand breaks to initiate meiotic recombination. Consistent with this, double-strand breaks are increased in number and persist longer in germlines with mitotic defects. These findings reveal that the process of initiating meiotic recombination inherently selects against nuclei with abnormal chromosomal content generated by mitotic errors, thereby ensuring the genomic integrity of gametes.

  20. A mitotic kinase scaffold depleted in testicular seminomas impacts spindle orientation in germ line stem cells

    PubMed Central

    Hehnly, Heidi; Canton, David; Bucko, Paula; Langeberg, Lorene K; Ogier, Leah; Gelman, Irwin; Santana, L Fernando; Wordeman, Linda; Scott, John D

    2015-01-01

    Correct orientation of the mitotic spindle in stem cells underlies organogenesis. Spindle abnormalities correlate with cancer progression in germ line-derived tumors. We discover a macromolecular complex between the scaffolding protein Gravin/AKAP12 and the mitotic kinases, Aurora A and Plk1, that is down regulated in human seminoma. Depletion of Gravin correlates with an increased mitotic index and disorganization of seminiferous tubules. Biochemical, super-resolution imaging, and enzymology approaches establish that this Gravin scaffold accumulates at the mother spindle pole during metaphase. Manipulating elements of the Gravin-Aurora A-Plk1 axis prompts mitotic delay and prevents appropriate assembly of astral microtubules to promote spindle misorientation. These pathological responses are conserved in seminiferous tubules from Gravin−/− mice where an overabundance of Oct3/4 positive germ line stem cells displays randomized orientation of mitotic spindles. Thus, we propose that Gravin-mediated recruitment of Aurora A and Plk1 to the mother (oldest) spindle pole contributes to the fidelity of symmetric cell division. DOI: http://dx.doi.org/10.7554/eLife.09384.001 PMID:26406118

  1. A mitotic kinase scaffold depleted in testicular seminomas impacts spindle orientation in germ line stem cells.

    PubMed

    Hehnly, Heidi; Canton, David; Bucko, Paula; Langeberg, Lorene K; Ogier, Leah; Gelman, Irwin; Santana, L Fernando; Wordeman, Linda; Scott, John D

    2015-01-01

    Correct orientation of the mitotic spindle in stem cells underlies organogenesis. Spindle abnormalities correlate with cancer progression in germ line-derived tumors. We discover a macromolecular complex between the scaffolding protein Gravin/AKAP12 and the mitotic kinases, Aurora A and Plk1, that is down regulated in human seminoma. Depletion of Gravin correlates with an increased mitotic index and disorganization of seminiferous tubules. Biochemical, super-resolution imaging, and enzymology approaches establish that this Gravin scaffold accumulates at the mother spindle pole during metaphase. Manipulating elements of the Gravin-Aurora A-Plk1 axis prompts mitotic delay and prevents appropriate assembly of astral microtubules to promote spindle misorientation. These pathological responses are conserved in seminiferous tubules from Gravin(-/-) mice where an overabundance of Oct3/4 positive germ line stem cells displays randomized orientation of mitotic spindles. Thus, we propose that Gravin-mediated recruitment of Aurora A and Plk1 to the mother (oldest) spindle pole contributes to the fidelity of symmetric cell division. PMID:26406118

  2. Heat shock protein inhibitors, 17-DMAG and KNK437, enhance arsenic trioxide-induced mitotic apoptosis

    SciTech Connect

    Wu Yichen; Yen Wenyen; Lee, T.-C. Yih, L.-H.

    2009-04-15

    Arsenic trioxide (ATO) has recently emerged as a promising therapeutic agent in leukemia because of its ability to induce apoptosis. However, there is no sufficient evidence to support its therapeutic use for other types of cancers. In this study, we investigated if, and how, 17-dimethylaminoethylamino-17-demethoxy-geldanamycin (17-DMAG), an antagonist of heat shock protein 90 (HSP90), and KNK437, a HSP synthesis inhibitor, potentiated the cytotoxic effect of ATO. Our results showed that cotreatment with ATO and either 17-DMAG or KNK437 significantly increased ATO-induced cell death and apoptosis. siRNA-mediated attenuation of the expression of the inducible isoform of HSP70 (HSP70i) or HSP90{alpha}/{beta} also enhanced ATO-induced apoptosis. In addition, cotreatment with ATO and 17-DMAG or KNK437 significantly increased ATO-induced mitotic arrest and ATO-induced BUBR1 phosphorylation and PDS1 accumulation. Cotreatment also significantly increased the percentage of mitotic cells with abnormal mitotic spindles and promoted metaphase arrest as compared to ATO treatment alone. These results indicated that 17-DMAG or KNK437 may enhance ATO cytotoxicity by potentiating mitotic arrest and mitotic apoptosis possibly through increased activation of the spindle checkpoint.

  3. Analysis of interchromosomal mitotic recombination.

    PubMed

    McGill, C B; Shafer, B K; Higgins, D R; Strathern, J N

    1990-07-01

    A novel synthetic locus is described that provides a simple assay system for characterizing mitotic recombinants. The locus consists of the TRP1 and HIS3 genes inserted into chromosome III of S. cerevisiae between the CRY1 and MAT loci. Defined trp1 and his3 alleles have been generated that allow the selection of interchromosomal recombinants in this interval. Trp+ or His+ recombinants can be divided into several classes based on coupling of the other alleles in the interval. The tight linkage of the CRY1 and MAT loci, combined with the drug resistance and cell type phenotypes that they respectively control, facilitates the classification of the recombinants without resorting to tetrad dissection. We present the distribution of spontaneous recombinants among the classes defined by this analysis. The data suggest that the recombination intermediate can have regions of symmetric strand exchange and that co-conversion tracts can extend over 1-3 kb. Continuous conversion tracts are favored over discontinuous tracts. The distribution among the classes defined by this analysis is altered in recombinants induced by UV irradiation.

  4. Meiotic abnormalities

    SciTech Connect

    1993-12-31

    Chapter 19, describes meiotic abnormalities. These include nondisjunction of autosomes and sex chromosomes, genetic and environmental causes of nondisjunction, misdivision of the centromere, chromosomally abnormal human sperm, male infertility, parental age, and origin of diploid gametes. 57 refs., 2 figs., 1 tab.

  5. DEK over-expression promotes mitotic defects and micronucleus formation

    PubMed Central

    Matrka, Marie C; Hennigan, Robert F; Kappes, Ferdinand; DeLay, Monica L; Lambert, Paul F; Aronow, Bruce J; Wells, Susanne I

    2015-01-01

    The DEK gene encodes a nuclear protein that binds chromatin and is involved in various fundamental nuclear processes including transcription, RNA splicing, DNA replication and DNA repair. Several cancer types characteristically over-express DEK at the earliest stages of transformation. In order to explore relevant mechanisms whereby DEK supports oncogenicity, we utilized cancer databases to identify gene transcripts whose expression patterns are tightly correlated with that of DEK. We identified an enrichment of genes involved in mitosis and thus investigated the regulation and possible function of DEK in cell division. Immunofluorescence analyses revealed that DEK dissociates from DNA in early prophase and re-associates with DNA during telophase in human keratinocytes. Mitotic cell populations displayed a sharp reduction in DEK protein levels compared to the corresponding interphase population, suggesting DEK may be degraded or otherwise removed from the cell prior to mitosis. Interestingly, DEK overexpression stimulated its own aberrant association with chromatin throughout mitosis. Furthermore, DEK co-localized with anaphase bridges, chromosome fragments, and micronuclei, suggesting a specific association with mitotically defective chromosomes. We found that DEK over-expression in both non-transformed and transformed cells is sufficient to stimulate micronucleus formation. These data support a model wherein normal chromosomal clearance of DEK is required for maintenance of high fidelity cell division and chromosomal integrity. Therefore, the overexpression of DEK and its incomplete removal from mitotic chromosomes promotes genomic instability through the generation of genetically abnormal daughter cells. Consequently, DEK over-expression may be involved in the initial steps of developing oncogenic mutations in cells leading to cancer initiation PMID:25945971

  6. DEK over-expression promotes mitotic defects and micronucleus formation.

    PubMed

    Matrka, Marie C; Hennigan, Robert F; Kappes, Ferdinand; DeLay, Monica L; Lambert, Paul F; Aronow, Bruce J; Wells, Susanne I

    2015-01-01

    The DEK gene encodes a nuclear protein that binds chromatin and is involved in various fundamental nuclear processes including transcription, RNA splicing, DNA replication and DNA repair. Several cancer types characteristically over-express DEK at the earliest stages of transformation. In order to explore relevant mechanisms whereby DEK supports oncogenicity, we utilized cancer databases to identify gene transcripts whose expression patterns are tightly correlated with that of DEK. We identified an enrichment of genes involved in mitosis and thus investigated the regulation and possible function of DEK in cell division. Immunofluorescence analyses revealed that DEK dissociates from DNA in early prophase and re-associates with DNA during telophase in human keratinocytes. Mitotic cell populations displayed a sharp reduction in DEK protein levels compared to the corresponding interphase population, suggesting DEK may be degraded or otherwise removed from the cell prior to mitosis. Interestingly, DEK overexpression stimulated its own aberrant association with chromatin throughout mitosis. Furthermore, DEK co-localized with anaphase bridges, chromosome fragments, and micronuclei, suggesting a specific association with mitotically defective chromosomes. We found that DEK over-expression in both non-transformed and transformed cells is sufficient to stimulate micronucleus formation. These data support a model wherein normal chromosomal clearance of DEK is required for maintenance of high fidelity cell division and chromosomal integrity. Therefore, the overexpression of DEK and its incomplete removal from mitotic chromosomes promotes genomic instability through the generation of genetically abnormal daughter cells. Consequently, DEK over-expression may be involved in the initial steps of developing oncogenic mutations in cells leading to cancer initiation.

  7. OECD in Figures, 2008

    ERIC Educational Resources Information Center

    OECD Publishing (NJ1), 2008

    2008-01-01

    "OECD in Figures" is a primary statistical source for key data on OECD countries, ranging from economic growth and employment to inflation, trade and environment. Information is presented in tabular form for: (1) Demography and Health; (2) Economy; (3) Energy; (4) Labour; (5) Science and Technology; (6) Environment; (7) Education; (8) Public…

  8. Craniofacial Abnormalities

    MedlinePlus

    ... of the skull and face. Craniofacial abnormalities are birth defects of the face or head. Some, like cleft ... palate, are among the most common of all birth defects. Others are very rare. Most of them affect ...

  9. Chromosome Abnormalities

    MedlinePlus

    ... decade, newer techniques have been developed that allow scientists and doctors to screen for chromosomal abnormalities without using a microscope. These newer methods compare the patient's DNA to a normal DNA ...

  10. Walking abnormalities

    MedlinePlus

    ... include: Arthritis of the leg or foot joints Conversion disorder (a psychological disorder) Foot problems (such as a ... injuries. For an abnormal gait that occurs with conversion disorder, counseling and support from family members are strongly ...

  11. Nail abnormalities

    MedlinePlus

    Beau's lines; Fingernail abnormalities; Spoon nails; Onycholysis; Leukonychia; Koilonychia; Brittle nails ... Just like the skin, the fingernails tell a lot about your health: ... the fingernail. These lines can occur after illness, injury to ...

  12. Disruption of a conserved CAP-D3 threonine alters condensin loading on mitotic chromosomes leading to chromosome hypercondensation.

    PubMed

    Bakhrebah, Muhammed; Zhang, Tao; Mann, Jeff R; Kalitsis, Paul; Hudson, Damien F

    2015-03-01

    The condensin complex plays a key role in organizing mitotic chromosomes. In vertebrates, there are two condensin complexes that have independent and cooperative roles in folding mitotic chromosomes. In this study, we dissect the role of a putative Cdk1 site on the condensin II subunit CAP-D3 in chicken DT40 cells. This conserved site has been shown to activate condensin II during prophase in human cells, and facilitate further phosphorylation by polo-like kinase I. We examined the functional significance of this phosphorylation mark by mutating the orthologous site of CAP-D3 (CAP-D3(T1403A)) in chicken DT40 cells. We show that this mutation is a gain of function mutant in chicken cells; it disrupts prophase, results in a dramatic shortening of the mitotic chromosome axis, and leads to abnormal INCENP localization. Our results imply phosphorylation of CAP-D3 acts to limit condensin II binding onto mitotic chromosomes. We present the first in vivo example that alters the ratio of condensin I:II on mitotic chromosomes. Our results demonstrate this ratio is a critical determinant in shaping mitotic chromosomes.

  13. Quantitative assessment of chromosome instability induced through chemical disruption of mitotic progression

    PubMed Central

    Markossian, Sarine; Arnaoutov, Alexei; Saba, Nakhle S.; Larionov, Vladimir; Dasso, Mary

    2016-01-01

    ABSTRACT Most solid tumors are aneuploid, carrying an abnormal number of chromosomes, and they frequently missegregate whole chromosomes in a phenomenon termed chromosome instability (CIN). While CIN can be provoked through disruption of numerous mitotic pathways, it is not clear which of these mechanisms are most critical, or whether alternative mechanisms could also contribute significantly in vivo. One difficulty in determining the relative importance of candidate CIN regulators has been the lack of a straightforward, quantitative assay for CIN in live human cells: While gross mitotic abnormalities can be detected visually, moderate levels of CIN may not be obvious, and are thus problematic to measure. To address this issue, we have developed the first Human Artificial Chromosome (HAC)-based quantitative live-cell assay for mitotic chromosome segregation in human cells. We have produced U2OS-Phoenix cells carrying the alphoidtetO-HAC encoding copies of eGFP fused to the destruction box (DB) of anaphase promoting complex/cyclosome (APC/C) substrate hSecurin and sequences encoding the tetracycline repressor fused to mCherry (TetR-mCherry). Upon HAC missegregation, daughter cells that do not obtain a copy of the HAC are GFP negative in the subsequent interphase. The HAC can also be monitored live following the TetR-mCherry signal. U2OS-Phoenix cells show low inherent levels of CIN, which can be enhanced by agents that target mitotic progression through distinct mechanisms. This assay allows direct detection of CIN induced by clinically important agents without conspicuous mitotic defects, allowing us to score increased levels of CIN that fall below the threshold required for discernable morphological disruption. PMID:27104376

  14. Moderate intensity static magnetic fields affect mitotic spindles and increase the antitumor efficacy of 5-FU and Taxol.

    PubMed

    Luo, Yan; Ji, Xinmiao; Liu, Juanjuan; Li, Zhiyuan; Wang, Wenchao; Chen, Wei; Wang, Junfeng; Liu, Qingsong; Zhang, Xin

    2016-06-01

    Microtubules are the fundamental components in mitotic spindle, which plays essential roles in cell division. It was well known that purified microtubules could be affected by static magnetic fields (SMFs) in vitro because of the diamagnetic anisotropy of tubulin. However, whether these effects lead to cell division defects was unknown. Here we find that 1T SMFs induce abnormal mitotic spindles and increase mitotic index. Synchronization experiments show that SMFs delay cell exit from mitosis and cause mitotic arrest. These mimic the cellular effects of a microtubule-targeting drug Paclitaxel (Taxol), which is frequently used in combination with 5-Fluorouracil (5-FU) and Cisplatin in cancer treatment. Using four different human cancer cell lines, HeLa, HCT116, CNE-2Z and MCF7, we find that SMFs increase the antitumor efficacy of 5-FU or 5-FU/Taxol, but not Cisplatin, which indicates that the SMF-induced combinational effects with chemodrugs are drug-specific. Our study not only reveals the effect of SMFs on microtubules to cause abnormal mitotic spindles and delay cells exit from mitosis, but also implies the potential applications of SMFs in combination with chemotherapy drugs 5-FU or 5-FU/Taxol, but not with Cisplatin in cancer treatment.

  15. Evidence that phosphorylation by the mitotic kinase Cdk1 promotes ICER monoubiquitination and nuclear delocalization

    SciTech Connect

    Memin, Elisabeth; Genzale, Megan; Crow, Marni; Molina, Carlos A.

    2011-10-15

    In contrast to normal prostatic cells, the transcriptional repressor Inducible cAMP Early Repressor (ICER) is undetected in the nuclei of prostate cancer cells. The molecular mechanisms for ICER abnormal expression in prostate cancer cells remained largely unknown. In this report data is presented demonstrating that ICER is phosphorylated by the mitotic kinase cdk1. Phosphorylation of ICER on a discrete residue targeted ICER to be monoubiquitinated. Different from unphosphorylated, phosphorylated and polyubiquitinated ICER, monoubiquitinated ICER was found to be cytosolic. Taken together, these results hinted on a mechanism for the observed abnormal subcellular localization of ICER in human prostate tumors.

  16. THE DIRECT ISOLATION OF THE MITOTIC APPARATUS

    PubMed Central

    Mazia, Daniel; Mitchison, J. M.; Medina, Heitor; Harris, Patricia

    1961-01-01

    A method for isolating the mitotic apparatus from dividing sea urchin eggs without the use of ethyl alcohol or of detergents is described. In the present method, the eggs are dispersed directly in a medium containing 1 M (to 1.15 M) sucrose, 0.15 M dithiodiglycol, and 0.001 M Versene at pH 6, releasing the visibly intact mitotic apparatus. The method is designed for studies of enzyme activities, lipid components, and the variables affecting the stability of the apparatus. PMID:13768661

  17. Unique genomic structure and distinct mitotic behavior of ring chromosome 21 in two unrelated cases.

    PubMed

    Zhang, H Z; Xu, F; Seashore, M; Li, P

    2012-01-01

    A ring chromosome replacing a normal chromosome could involve variable structural rearrangements and mitotic instability. However, most previously reported cases lacked further genomic characterization. High-resolution oligonucleotide array comparative genomic hybridization with single-nucleotide polymorphism typing (aCGH+SNP) was used to study 2 unrelated cases with a ring chromosome 21. Case 1 had severe myopia, hypotonia, joint hypermobility, speech delay, and dysmorphic features. aCGH detected a 1.275-Mb duplication of 21q22.12-q22.13 and a 6.731-Mb distal deletion at 21q22.2. Case 2 showed severe growth and developmental retardations, intractable seizures, and dysmorphic features. aCGH revealed a contiguous pattern of a 3.612- Mb deletion of 21q22.12-q22.2, a 4.568-Mb duplication of 21q22.2-q22.3, and a 2.243-Mb distal deletion at 21q22.3. Mitotic instability was noted in 13, 30, and 76% of in vitro cultured metaphase cells, interphase cells, and leukocyte DNA, respectively. The different phenotypes of these 2 cases are likely associated with the unique genomic structure and distinct mitotic behavior of their ring chromosome 21. These 2 cases represent a subtype of ring chromosome 21 probably involving somatic dicentric ring breakage and reunion. A cytogenomic approach is proposed for characterizing the genomic structure and mitotic instability of ring chromosome abnormalities.

  18. Rapid measurement of mitotic spindle orientation in cultured mammalian cells

    PubMed Central

    Decarreau, Justin; Driver, Jonathan; Asbury, Charles; Wordeman, Linda

    2014-01-01

    Summary Factors that influence the orientation of the mitotic spindle are important for the maintenance of stem cell populations and in cancer development. However, screening for these factors requires rapid quantification of alterations of the angle of the mitotic spindle in cultured cell lines. Here we describe a method to image mitotic cells and rapidly score the angle of the mitotic spindle using a simple MATLAB application to analyze a stack of Z-images. PMID:24633791

  19. Disruption of Mitotic Progression by Arsenic.

    PubMed

    States, J Christopher

    2015-07-01

    Arsenic is an enigmatic xenobiotic that causes a multitude of chronic diseases including cancer and also is a therapeutic with promise in cancer treatment. Arsenic causes mitotic delay and induces aneuploidy in diploid human cells. In contrast, arsenic causes mitotic arrest followed by an apoptotic death in a multitude of virally transformed cells and cancer cells. We have explored the hypothesis that these differential effects of arsenic exposure are related by arsenic disruption of mitosis and are differentiated by the target cell's ability to regulate or modify cell cycle checkpoints. Functional p53/CDKN1A axis has been shown to mitigate the mitotic block and to be essential to induction of aneuploidy. More recent preliminary data suggest that microRNA modulation of chromatid cohesion also may play a role in escape from mitotic block and in generation of chromosomal instability. Other recent studies suggest that arsenic may be useful in treatment of solid tumors when used in combination with other cytotoxic agents such as cisplatin.

  20. Mitotic Stress and Chromosomal Instability in Cancer

    PubMed Central

    Malumbres, Marcos

    2012-01-01

    Cell cycle deregulation is a common motif in human cancer, and multiple therapeutic strategies are aimed to prevent tumor cell proliferation. Whereas most current therapies are designed to arrest cell cycle progression either in G1/S or in mitosis, new proposals include targeting the intrinsic chromosomal instability (CIN, an increased rate of gain or losses of chromosomes during cell division) or aneuploidy (a genomic composition that differs from diploid) that many tumor cells display. Why tumors cells are chromosomally unstable or aneuploid and what are the consequences of these alterations are not completely clear at present. Several mitotic regulators are overexpressed as a consequence of oncogenic alterations, and they are likely to alter the proper regulation of chromosome segregation in cancer cells. In this review, we propose the relevance of TPX2, a mitotic regulator involved in the formation of the mitotic spindle, in oncogene-induced mitotic stress. This protein, as well as its partner Aurora-A, is frequently overexpressed in human cancer, and its deregulation may participate not only in chromosome numeric aberrations but also in other forms of genomic instability in cancer cells. PMID:23634259

  1. Proteomic profiling revealed the functional networks associated with mitotic catastrophe of HepG2 hepatoma cells induced by 6-bromine-5-hydroxy-4-methoxybenzaldehyde

    SciTech Connect

    Zhang Bo; Huang Bo; Guan Hua; Zhang Shimeng; Xu Qinzhi; He Xingpeng; Liu Xiaodan; Wang Yu; Shang Zengfu; Zhou Pingkun

    2011-05-01

    Mitotic catastrophe, a form of cell death resulting from abnormal mitosis, is a cytotoxic death pathway as well as an appealing mechanistic strategy for the development of anti-cancer drugs. In this study, 6-bromine-5-hydroxy-4-methoxybenzaldehyde was demonstrated to induce DNA double-strand break, multipolar spindles, sustain mitotic arrest and generate multinucleated cells, all of which indicate mitotic catastrophe, in human hepatoma HepG2 cells. We used proteomic profiling to identify the differentially expressed proteins underlying mitotic catastrophe. A total of 137 differentially expressed proteins (76 upregulated and 61 downregulated proteins) were identified. Some of the changed proteins have previously been associated with mitotic catastrophe, such as DNA-PKcs, FoxM1, RCC1, cyclin E, PLK1-pT210, 14-3-3{sigma} and HSP70. Multiple isoforms of 14-3-3, heat-shock proteins and tubulin were upregulated. Analysis of functional significance revealed that the 14-3-3-mediated signaling network was the most significantly enriched for the differentially expressed proteins. The modulated proteins were found to be involved in macromolecule complex assembly, cell death, cell cycle, chromatin remodeling and DNA repair, tubulin and cytoskeletal organization. These findings revealed the overall molecular events and functional signaling networks associated with spindle disruption and mitotic catastrophe. - Graphical abstract: Display Omitted Research highlights: > 6-bromoisovanillin induced spindle disruption and sustained mitotic arrest, consequently resulted in mitotic catastrophe. > Proteomic profiling identified 137 differentially expressed proteins associated mitotic catastrophe. > The 14-3-3-mediated signaling network was the most significantly enriched for the altered proteins. > The macromolecule complex assembly, cell cycle, chromatin remodeling and DNA repair, tubulin organization were also shown involved in mitotic catastrophe.

  2. Figuring Out Fat and Calories

    MedlinePlus

    ... I Help a Friend Who Cuts? Figuring Out Fat and Calories KidsHealth > For Teens > Figuring Out Fat ... the truth on fat and calories? What Are Fat and Calories? Fats, or lipids , are nutrients in ...

  3. The Aurora-A inhibitor MLN8237 affects multiple mitotic processes and induces dose-dependent mitotic abnormalities and aneuploidy

    PubMed Central

    Asteriti, Italia Anna; Cesare, Erica Di; Mattia, Fabiola De; Hilsenstein, Volker; Neumann, Beate; Cundari, Enrico; Lavia, Patrizia; Guarguaglini, Giulia

    2014-01-01

    Inhibition of Aurora kinase activity by small molecules is being actively investigated as a potential anti-cancer strategy. A successful therapeutic use of Aurora inhibitors relies on a comprehensive understanding of the effects of inactivating Aurora kinases on cell division, a challenging aim given the pleiotropic roles of those kinases during mitosis. Here we have used the Aurora-A inhibitor MLN8237, currently under phase-I/III clinical trials, in dose-response assays in U2OS human cancer cells synchronously proceeding towards mitosis. By following the behaviour and fate of single Aurora-inhibited cells in mitosis by live microscopy, we show that MLN8237 treatment affects multiple processes that are differentially sensitive to the loss of Aurora-A function. A role of Aurora-A in controlling the orientation of cell division emerges. MLN8237 treatment, even in high doses, fails to induce efficient elimination of dividing cells, or of their progeny, while inducing significant aneuploidy in daughter cells. The results of single-cell analyses show a complex cellular response to MLN8237 and evidence that its effects are strongly dose-dependent: these issues deserve consideration in the light of the design of strategies to kill cancer cells via inhibition of Aurora kinases. PMID:25153724

  4. Growth of breath figures

    NASA Astrophysics Data System (ADS)

    Beysens, D.; Knobler, C. M.

    1986-09-01

    Measurements are reported of the growth of breath figures, the patterns that form when a vapor is condensed onto a cold surface. Water vapor was condensed on glass slides and the pattern was studied by direct observation and light scattering as a function of the contact angle theta, flux F, degree of supersaturation ΔT, and time t. When theta=0°, a uniform layer forms whose thickness grows as t at constant F and ΔT. For theta=90°, droplets are formed; at constant F and T, the radius of an isolated droplet grows as t0.23, but, as a result of coalescences, the average droplet radius grows as t0.75. The droplet growth process is self-similar-coalescences simply rescale the distances and leave the basic droplet pattern unaltered.

  5. Making better scientific figures

    NASA Astrophysics Data System (ADS)

    Hawkins, Ed; McNeall, Doug

    2016-04-01

    In the words of the UK government chief scientific adviser "Science is not finished until it's communicated" (Walport 2013). The tools to produce good visual communication have never been so easily accessible to scientists as at the present. Correspondingly, it has never been easier to produce and disseminate poor graphics. In this presentation, we highlight some good practice and offer some practical advice in preparing scientific figures for presentation to peers or to the public. We identify common mistakes in visualisation, including some made by the authors, and offer some good reasons not to trust defaults in graphics software. In particular, we discuss the use of colour scales and share our experiences in running a social media campaign (http://tiny.cc/endrainbow) to replace the "rainbow" (also "jet", or "spectral") colour scale as the default in (climate) scientific visualisation.

  6. Plk1 Inhibition Causes Post-Mitotic DNA Damage and Senescence in a Range of Human Tumor Cell Lines

    PubMed Central

    Bowman, Doug; Shinde, Vaishali; Lasky, Kerri; Shi, Judy; Vos, Tricia; Stringer, Bradley; Amidon, Ben; D'Amore, Natalie; Hyer, Marc L.

    2014-01-01

    Plk1 is a checkpoint protein whose role spans all of mitosis and includes DNA repair, and is highly conserved in eukaryotes from yeast to man. Consistent with this wide array of functions for Plk1, the cellular consequences of Plk1 disruption are diverse, spanning delays in mitotic entry, mitotic spindle abnormalities, and transient mitotic arrest leading to mitotic slippage and failures in cytokinesis. In this work, we present the in vitro and in vivo consequences of Plk1 inhibition in cancer cells using potent, selective small-molecule Plk1 inhibitors and Plk1 genetic knock-down approaches. We demonstrate for the first time that cellular senescence is the predominant outcome of Plk1 inhibition in some cancer cell lines, whereas in other cancer cell lines the dominant outcome appears to be apoptosis, as has been reported in the literature. We also demonstrate strong induction of DNA double-strand breaks in all six lines examined (as assayed by γH2AX), which occurs either during mitotic arrest or mitotic-exit, and may be linked to the downstream induction of senescence. Taken together, our findings expand the view of Plk1 inhibition, demonstrating the occurrence of a non-apoptotic outcome in some settings. Our findings are also consistent with the possibility that mitotic arrest observed as a result of Plk1 inhibition is at least partially due to the presence of unrepaired double-strand breaks in mitosis. These novel findings may lead to alternative strategies for the development of novel therapeutic agents targeting Plk1, in the selection of biomarkers, patient populations, combination partners and dosing regimens. PMID:25365521

  7. Pb-inhibited mitotic activity in onion roots involves DNA damage and disruption of oxidative metabolism.

    PubMed

    Kaur, Gurpreet; Singh, Harminder Pal; Batish, Daizy Rani; Kohli, Ravinder Kumar

    2014-09-01

    Plant responses to abiotic stress significantly affect the development of cells, tissues and organs. However, no studies correlating Pb-induced mitotic inhibition and DNA damage and the alterations in redox homeostasis during root division per se were found in the literature. Therefore, an experiment was conducted to evaluate the impact of Pb on mitotic activity and the associated changes in the oxidative metabolism in onion roots. The cytotoxic effect of Pb on cell division was assessed in the root meristems of Allium cepa (onion). The mitotic index (MI) was calculated and chromosomal abnormalities were sought. Pb-treatment induced a dose-dependent decrease in MI in the onion root tips and caused mitotic abnormalities such as distorted metaphase, fragments, sticky chromosomes, laggards, vagrant chromosomes and bridges. Single Cell Gel Electrophoresis was also performed to evaluate Pb induced genotoxicity. It was accompanied by altered oxidative metabolism in the onion root tips suggesting the interference of Pb with the redox homeostasis during cell division. There was a higher accumulation of malondialdehyde, conjugated dienes and hydrogen peroxide, and a significant increase in the activities of superoxide dismutases, ascorbate peroxidases, guaiacol peroxidases and glutathione reductases in Pb-treated onion roots, whereas catalases activity exhibited a decreasing pattern upon Pb exposure. The study concludes that Pb-induced cytotoxicity and genotoxicity in the onion roots is mediated through ROS and is also tightly linked to the cell cycle. The exposure to higher concentrations arrested cell cycle leading to cell death, whereas different repair responses are generated at lower concentrations, thereby allowing the cell to complete the cell cycle.

  8. Measuring mitotic spindle dynamics in budding yeast

    NASA Astrophysics Data System (ADS)

    Plumb, Kemp

    In order to carry out its life cycle and produce viable progeny through cell division, a cell must successfully coordinate and execute a number of complex processes with high fidelity, in an environment dominated by thermal noise. One important example of such a process is the assembly and positioning of the mitotic spindle prior to chromosome segregation. The mitotic spindle is a modular structure composed of two spindle pole bodies, separated in space and spanned by filamentous proteins called microtubules, along which the genetic material of the cell is held. The spindle is responsible for alignment and subsequent segregation of chromosomes into two equal parts; proper spindle positioning and timing ensure that genetic material is appropriately divided amongst mother and daughter cells. In this thesis, I describe fluorescence confocal microscopy and automated image analysis algorithms, which I have used to observe and analyze the real space dynamics of the mitotic spindle in budding yeast. The software can locate structures in three spatial dimensions and track their movement in time. By selecting fluorescent proteins which specifically label the spindle poles and cell periphery, mitotic spindle dynamics have been measured in a coordinate system relevant to the cell division. I describe how I have characterised the accuracy and precision of the algorithms by simulating fluorescence data for both spindle poles and the budding yeast cell surface. In this thesis I also describe the construction of a microfluidic apparatus that allows for the measurement of long time-scale dynamics of individual cells and the development of a cell population. The tools developed in this thesis work will facilitate in-depth quantitative analysis of the non-equilibrium processes in living cells.

  9. Automatic microscopy for mitotic cell location.

    NASA Technical Reports Server (NTRS)

    Herron, J.; Ranshaw, R.; Castle, J.; Wald, N.

    1972-01-01

    Advances are reported in the development of an automatic microscope with which to locate hematologic or other cells in mitosis for subsequent chromosome analysis. The system under development is designed to perform the functions of: slide scanning to locate metaphase cells; conversion of images of selected cells into binary form; and on-line computer analysis of the digitized image for significant cytogenetic data. Cell detection criteria are evaluated using a test sample of 100 mitotic cells and 100 artifacts.

  10. Nuclear Chk1 prevents premature mitotic entry.

    PubMed

    Matsuyama, Makoto; Goto, Hidemasa; Kasahara, Kousuke; Kawakami, Yoshitaka; Nakanishi, Makoto; Kiyono, Tohru; Goshima, Naoki; Inagaki, Masaki

    2011-07-01

    Chk1 inhibits the premature activation of the cyclin-B1-Cdk1. However, it remains controversial whether Chk1 inhibits Cdk1 in the centrosome or in the nucleus before the G2-M transition. In this study, we examined the specificity of the mouse monoclonal anti-Chk1 antibody DCS-310, with which the centrosome was stained. Conditional Chk1 knockout in mouse embryonic fibroblasts reduced nuclear but not centrosomal staining with DCS-310. In Chk1(+/myc) human colon adenocarcinoma (DLD-1) cells, Chk1 was detected in the nucleus but not in the centrosome using an anti-Myc antibody. Through the combination of protein array and RNAi technologies, we identified Ccdc-151 as a protein that crossreacted with DCS-310 on the centrosome. Mitotic entry was delayed by expression of the Chk1 mutant that localized in the nucleus, although forced immobilization of Chk1 to the centrosome had little impact on the timing of mitotic entry. These results suggest that nuclear but not centrosomal Chk1 contributes to correct timing of mitotic entry.

  11. Nuclear Chk1 prevents premature mitotic entry.

    PubMed

    Matsuyama, Makoto; Goto, Hidemasa; Kasahara, Kousuke; Kawakami, Yoshitaka; Nakanishi, Makoto; Kiyono, Tohru; Goshima, Naoki; Inagaki, Masaki

    2011-07-01

    Chk1 inhibits the premature activation of the cyclin-B1-Cdk1. However, it remains controversial whether Chk1 inhibits Cdk1 in the centrosome or in the nucleus before the G2-M transition. In this study, we examined the specificity of the mouse monoclonal anti-Chk1 antibody DCS-310, with which the centrosome was stained. Conditional Chk1 knockout in mouse embryonic fibroblasts reduced nuclear but not centrosomal staining with DCS-310. In Chk1(+/myc) human colon adenocarcinoma (DLD-1) cells, Chk1 was detected in the nucleus but not in the centrosome using an anti-Myc antibody. Through the combination of protein array and RNAi technologies, we identified Ccdc-151 as a protein that crossreacted with DCS-310 on the centrosome. Mitotic entry was delayed by expression of the Chk1 mutant that localized in the nucleus, although forced immobilization of Chk1 to the centrosome had little impact on the timing of mitotic entry. These results suggest that nuclear but not centrosomal Chk1 contributes to correct timing of mitotic entry. PMID:21628425

  12. Mitotic spindle studied using picosecond laser scissors

    NASA Astrophysics Data System (ADS)

    Baker, N. M.; Botvinick, E. L.; Shi, Linda; Berns, M. B.; Wu, George

    2006-08-01

    In previous studies we have shown that the second harmonic 532 nm, from a picosecond frequency doubled Nd:YAG laser, can cleanly and selectively disrupt spindle fiber microtubules in live cells (Botvinick et al 2004, Biophys. J. 87:4303-4212). In the present study we have ablated different locations and amounts of the metaphase mitotic spindle, and followed the cells in order to observe the fate of the irradiated spindle and the ability of the cell to continue through mitosis. Cells of the rat kangaroo line (PTK2) were stably transfected by ECFP-tubulin and, using fluorescent microscopy and the automated RoboLase microscope, (Botvinick and Berns, 2005, Micros. Res. Tech. 68:65-74) brightly fluorescent individual cells in metaphase were irradiated with 0.2447 nJ/micropulse corresponding to an irradiance of 1.4496*10^7 J/(ps*cm^2) . Upon irradiation the exposed part of the mitotic spindle immediately lost fluorescence and the following events were observed in the cells over time: (1) immediate contraction of the spindle pole towards the cut, (2) recovery of connection between pole and cut microtubule, (3) completion of mitosis. This system should be very useful in studying internal cellular dynamics of the mitotic spindle.

  13. Chemically Diverse Microtubule Stabilizing Agents Initiate Distinct Mitotic Defects and Dysregulated Expression of Key Mitotic Kinases

    PubMed Central

    Rohena, Cristina C.; Peng, Jiangnan; Johnson, Tyler A.; Crews, Phillip; Mooberry, Susan L.

    2013-01-01

    Microtubule stabilizers are some of the most successful drugs used in the treatment of adult solid tumors and yet the molecular events responsible for their antimitotic actions are not well defined. The mitotic events initiated by three structurally and biologically diverse microtubule stabilizers; taccalonolide AJ, laulimalide/fijianolide B and paclitaxel were studied. These microtubule stabilizers cause the formation of aberrant, but structurally distinct mitotic spindles leading to the hypothesis that they differentially affect mitotic signaling. Each microtubule stabilizer initiated different patterns of expression of key mitotic signaling proteins. Taccalonolide AJ causes centrosome separation and disjunction failure to a much greater extent than paclitaxel or laulimalide, which is consistent with the distinct defects in expression and activation of Plk1 and Eg5 caused by each stabilizer. Localization studies revealed that TPX2 and Aurora A are associated with each spindle aster formed by each stabilizer. This suggests a common mechanism of aster formation. However, taccalonolide AJ also causes pericentrin accumulation on every spindle aster. The presence of pericentrin at every spindle aster initiated by taccalonolide AJ might facilitate the maintenance and stability of the highly focused asters formed by this stabilizer. Laulimalide and paclitaxel cause completely different patterns of expression and activation of these proteins, as well as phenotypically different spindle phenotypes. Delineating how diverse microtubule stabilizers affect mitotic signaling pathways could identify key proteins involved in modulating sensitivity and resistance to the antimitotic actions of these compounds. PMID:23399639

  14. A reconfigured pattern of MLL occupancy within mitotic chromatin promotes rapid transcriptional reactivation following mitotic exit.

    PubMed

    Blobel, Gerd A; Kadauke, Stephan; Wang, Eric; Lau, Alan W; Zuber, Johannes; Chou, Margaret M; Vakoc, Christopher R

    2009-12-25

    Mixed lineage leukemia (MLL) and its metazoan Trithorax orthologs have been linked with the epigenetic maintenance of transcriptional activity. To identify mechanisms by which MLL perpetuates active transcription in dividing cells, we investigated its role during M phase of the cell cycle. Unlike other chromatin-modifying enzymes examined, we found that MLL associates with gene promoters packaged within condensed mitotic chromosomes. Genome-wide location analysis identified a globally rearranged pattern of MLL occupancy during mitosis in a manner favoring genes that were highly transcribed during interphase. Knockdown experiments revealed that MLL retention at gene promoters during mitosis accelerates transcription reactivation following mitotic exit. MLL tethers Menin, RbBP5, and ASH2L to its occupied sites during mitosis, but is dispensable for preserving histone H3K4 methylation. These findings implicate mitotic bookmarking as a component of Trithorax-based gene regulation, which may facilitate inheritance of active gene expression states during cell division. PMID:20064463

  15. Implications of mitotic and meiotic irregularities in common beans (Phaseolus vulgaris L.).

    PubMed

    Lima, D C; Braz, G T; Dos Reis, G B; Techio, V H; Davide, L C; de F B Abreu, A

    2016-01-01

    The common bean has great social and economic importance in Brazil and is the subject of a high number of publications, especially in the fields of genetics and breeding. Breeding programs aim to increase grain yield; however, mitosis and meiosis represent under explored research areas that have a direct impact on grain yield. Therefore, the study of cell division could be another tool available to bean geneticists and breeders. The aim of this study was to investigate irregularities occurring during the cell cycle and meiosis in common bean. The common bean cultivar used was BRSMG Talismã, which owing to its high yield and grain quality is recommended for cultivation in Brazil. We classified the interphase nuclei, estimated the mitotic and meiotic index, grain pollen viability, and percentage of abnormalities in both processes. The mitotic index was 4.1%, the interphase nucleus was non-reticulated, and 19% of dividing somatic cells showed abnormal behavior. Meiosis also presented irregularities resulting in a meiotic index of 44.6%. Viability of pollen grains was 94.3%. These results indicate that the common bean cultivar BRSMG Talismã possesses repair mechanisms that compensate for changes by producing a large number of pollen grains. Another important strategy adopted by bean plants to ensure stability is the elimination of abnormal cells by apoptosis. As the common bean cultivar BRSMG Talismã is recommended for cultivation because of its good agronomic performance, it can be concluded that mitotic and meiotic irregularities have no negative influence on its grain quality and yield. PMID:27323072

  16. Three-Dimensional Lissajous Figures.

    ERIC Educational Resources Information Center

    D'Mura, John M.

    1989-01-01

    Described is a mechanically driven device for generating three-dimensional harmonic space figures with different frequencies and phase angles on the X, Y, and Z axes. Discussed are apparatus, viewing stereo pairs, equations of motion, and using space figures in classroom. (YP)

  17. Figure Analysis: An Implementation Dialogue

    ERIC Educational Resources Information Center

    Wiles, Amy M.

    2016-01-01

    Figure analysis is a novel active learning teaching technique that reinforces visual literacy. Small groups of students discuss diagrams in class in order to learn content. The instructor then gives a brief introduction and later summarizes the content of the figure. This teaching technique can be used in place of lecture as a mechanism to deliver…

  18. Mitotic arrest and toxicity in Biomphalaria glabrata (Mollusca: Pulmonata) exposed to colchicine.

    PubMed

    Sullivan, John T; Castro, Lina

    2005-09-01

    Continuous exposure of Biomphalaria glabrata snails to 0.1% colchicine resulted in a significant increase, relative to non-exposed snails, in the number of arrested mitotic figures in the amebocyte-producing organ (APO) as soon as 4 h, with peak numbers after 12 h of exposure. The number of circulating hemocytes was significantly elevated at 24 h. However, by 72 h both the number of mitotic figures in the APO and the concentration of circulating hemocytes in the hemolymph had returned to control levels. Hemocytes appeared to possess normal morphology throughout this exposure, including the formation of long filopodia with supporting rodlike structures that have been reported to contain microtubules. Snail survival decreased as a function of exposure time. Significantly fewer snails, relative to controls, survived a 48-h exposure, and only 1 out of 30 snails recovered from a 72-h exposure to 0.1% colchicine. Colchicine-exposed snails displayed intoxicated behavior, even upon removal from the colchicine solution, although no histopathology was evident in the CNS of snails exposed for 72 h.

  19. Novel insights into mitotic chromosome condensation

    PubMed Central

    Piskadlo, Ewa; Oliveira, Raquel A.

    2016-01-01

    The fidelity of mitosis is essential for life, and successful completion of this process relies on drastic changes in chromosome organization at the onset of nuclear division. The mechanisms that govern chromosome compaction at every cell division cycle are still far from full comprehension, yet recent studies provide novel insights into this problem, challenging classical views on mitotic chromosome assembly. Here, we briefly introduce various models for chromosome assembly and known factors involved in the condensation process (e.g. condensin complexes and topoisomerase II). We will then focus on a few selected studies that have recently brought novel insights into the mysterious way chromosomes are condensed during nuclear division. PMID:27508072

  20. Preventing farnesylation of the dynein adaptor Spindly contributes to the mitotic defects caused by farnesyltransferase inhibitors

    PubMed Central

    Holland, Andrew J.; Reis, Rita M.; Niessen, Sherry; Pereira, Cláudia; Andres, Douglas A.; Spielmann, H. Peter; Cleveland, Don W.; Desai, Arshad; Gassmann, Reto

    2015-01-01

    The clinical interest in farnesyltransferase inhibitors (FTIs) makes it important to understand how these compounds affect cellular processes involving farnesylated proteins. Mitotic abnormalities observed after treatment with FTIs have so far been attributed to defects in the farnesylation of the outer kinetochore proteins CENP-E and CENP-F, which are involved in chromosome congression and spindle assembly checkpoint signaling. Here we identify the cytoplasmic dynein adaptor Spindly as an additional component of the outer kinetochore that is modified by farnesyltransferase (FTase). We show that farnesylation of Spindly is essential for its localization, and thus for the proper localization of dynein and its cofactor dynactin, to prometaphase kinetochores and that Spindly kinetochore recruitment is more severely affected by FTase inhibition than kinetochore recruitment of CENP-E and CENP-F. Molecular replacement experiments show that both Spindly and CENP-E farnesylation are required for efficient chromosome congression. The identification of Spindly as a new mitotic substrate of FTase provides insight into the causes of the mitotic phenotypes observed with FTase inhibitors. PMID:25808490

  1. T-1, a mitotic arrester, alters centrosome configurations in fertilized sea urchin eggs.

    PubMed

    Itoh, T J; Schatten, H; Schatten, G; Mazia, D; Kobayashi, A; Sato, H

    1990-01-01

    T-1 induces modifications in the shape of the centrosome at division in fertilized eggs of the North American sea urchin, Lytechinus pictus. Phase contrast microscopy observations of mitotic apparatus isolated from T-1-treated (1.7-8.5 microM) eggs at first division shows that the centrosomes already begin to spread or to separate by prophase and that the mitotic spindle is barrel-shaped. When eggs are fertilized with sperm that have been preteated with T-1, the centrosomes become flattened; the spindles are of normal length. Immunofluorescence microscopy using an anti-centrosomal monoclonal antibody reveals that T-1 modifies the structure of the centrosome so that barrel-shaped spindles with broad centrosomes are observed at metaphase, rather than the expected focused poles and fusiform spindle. Higher concentrations of T-1 induce fragmentation of centrosomes, causing abnormal accumulation of microtubules in polar regions. These results indicate that T-1 directly alters centrosomal configuration from a compact structure to a flattened or a spread structure. T-1 can be classified as a new category of mitotic drugs that may prove valuable in dissecting the molecular nature of centrosomes.

  2. Post-slippage multinucleation renders cytotoxic variation in anti-mitotic drugs that target the microtubules or mitotic spindle.

    PubMed

    Zhu, Yanting; Zhou, Yuan; Shi, Jue

    2014-01-01

    One common cancer chemotherapeutic strategy is to perturb cell division with anti-mitotic drugs. Paclitaxel, the classic microtubule-targeting anti-mitotic drug, so far still outperforms the newer, more spindle-specific anti-mitotics in the clinic, but the underlying cellular mechanism is poorly understood. In this study we identified post-slippage multinucleation, which triggered extensive DNA damage and apoptosis after drug-induced mitotic slippage, contributes to the extra cytotoxicity of paclitaxel in comparison to the spindle-targeting drug, Kinesin-5 inhibitor. Based on quantitative single-cell microscopy assays, we showed that attenuation of the degree of post-slippage multinucleation significantly reduced DNA damage and apoptosis in response to paclitaxel, and that post-slippage apoptosis was likely mediated by the p53-dependent DNA damage response pathway. Paclitaxel appeared to act as a double-edge sword, capable of killing proliferating cancer cells both during mitotic arrest and after mitotic slippage by inducing DNA damage. Our results thus suggest that to predict drug response to paclitaxel and anti-mitotics in general, 2 distinct sets of bio-markers, which regulate mitotic and post-slippage cytotoxicity, respectively, may need to be considered. Our findings provide important new insight not only for elucidating the cytotoxic mechanisms of paclitaxel, but also for understanding the variable efficacy of different anti-mitotic chemotherapeutics. PMID:24694730

  3. Mitotic recombination of chromosome 17 in astrocytomas

    SciTech Connect

    James, C.D.; Carlbom, E.; Nordenskjold, M.; Collins, V.P.; Cavenee, W.K. )

    1989-04-01

    Allelic combinations at seven loci on human chromosome 17 defined by restriction fragment length polymorphisms were determined in tumor and normal tissues from 35 patients with gliomas. Loss of constitutional heterozygosity at one or more of these loci was observed in 8 of the 24 tumors displaying astrocytic differentiation and in the single primitive neuroectodermal tumor examined. The astrocytomas showing these losses included examples of each adult malignancy grade of the disease, including glioblastoma (malignancy grade IV), and seven of them demonstrated concurrent maintenance of heterozygosity for at least one chromosome 17 locus. Determination of allele dosage together with the genotypic data indicated that the tumor chromosomes 17 were derived by mitotic recombination in 7 of the 9 cases with shared homozygosity of the region 17p11.2-ptr in all cases. In contrast, tumors of oligodendrocytic, ependymal, or mixed cellular differentiation did not exhibit loss of alleles at any of the loci examined. These data suggest that the somatic attainment of homozygosity for loci on chromosome 17p is frequently associated with the oncogenesis of central nervous system tumors, particularly those showing solely astrocytic differentiation, and that mitotic recombination mapping is a useful approach towards the subregional localization of a locus whose rearrangement is involved in this disease.

  4. Cancer Facts and Figures 2014

    MedlinePlus

    ... Facts & Figures 2014 This annual report provides the estimated numbers of new cancer cases and deaths in ... and treatment. In 2014, there will be an estimated 1,665,540 new cancer cases diagnosed and ...

  5. Identification of a mitotic death signature in cancer cell lines.

    PubMed

    Sakurikar, Nandini; Eichhorn, Joshua M; Alford, Sarah E; Chambers, Timothy C

    2014-02-28

    This study examined the molecular mechanism of action of anti-mitotic drugs. The hypothesis was tested that death in mitosis occurs through sustained mitotic arrest with robust Cdk1 signaling causing complete phosphorylation of Mcl-1 and Bcl-xL, and conversely, that mitotic slippage is associated with incomplete phosphorylation of Mcl-1/Bcl-xL. The results, obtained from studying six different cancer cell lines, strongly support the hypothesis and identify for the first time a unique molecular signature for mitotic death. The findings represent an important advance in understanding anti-mitotic drug action and provide insight into cancer cell susceptibility to such drugs which has important clinical implications. PMID:24099917

  6. Identification of a mitotic death signature in cancer cell lines.

    PubMed

    Sakurikar, Nandini; Eichhorn, Joshua M; Alford, Sarah E; Chambers, Timothy C

    2014-02-28

    This study examined the molecular mechanism of action of anti-mitotic drugs. The hypothesis was tested that death in mitosis occurs through sustained mitotic arrest with robust Cdk1 signaling causing complete phosphorylation of Mcl-1 and Bcl-xL, and conversely, that mitotic slippage is associated with incomplete phosphorylation of Mcl-1/Bcl-xL. The results, obtained from studying six different cancer cell lines, strongly support the hypothesis and identify for the first time a unique molecular signature for mitotic death. The findings represent an important advance in understanding anti-mitotic drug action and provide insight into cancer cell susceptibility to such drugs which has important clinical implications.

  7. Cellular and molecular etiology of hepatocyte injury in a murine model of environmentally induced liver abnormality

    PubMed Central

    Al-Griw, M.A.; Alghazeer, R.O.; Al-Azreg, S.A.; Bennour, E.M.

    2016-01-01

    Exposures to a wide variety of environmental substances are negatively associated with many biological cell systems both in humans and rodents. Trichloroethane (TCE), a ubiquitous environmental toxicant, is used in large quantities as a dissolvent, metal degreaser, chemical intermediate, and component of consumer products. This increases the likelihood of human exposure to these compounds through dermal, inhalation and oral routes. The present in vivo study was aimed to investigate the possible cellular and molecular etiology of liver abnormality induced by early exposure to TCE using a murine model. The results showed a significant increase in liver weight. Histopathological examination revealed a TCE-induced hepatotoxicity which appeared as heavily congested central vein and blood sinusoids as well as leukocytic infiltration. Mitotic figures and apoptotic changes such as chromatin condensation and nuclear fragments were also identified. Cell death analysis demonstrates hepatocellular apoptosis was evident in the treated mice compared to control. TCE was also found to induce oxidative stress as indicated by an increase in the levels of lipid peroxidation, an oxidative stress marker. There was also a significant decrease in the DNA content of the hepatocytes of the treated groups compared to control. Agarose gel electrophoresis also provided further biochemical evidence of apoptosis by showing internucleosomal DNA fragmentation in the liver cells, indicating oxidative stress as the cause of DNA damage. These results suggest the need for a complete risk assessment of any new chemical prior to its arrival into the consumer market. PMID:27800299

  8. Ki-67 proliferation index but not mitotic thresholds integrates the molecular prognostic stratification of lower grade gliomas

    PubMed Central

    Duregon, Eleonora; Bertero, Luca; Pittaro, Alessandra; Soffietti, Riccardo; Rudà, Roberta; Trevisan, Morena; Papotti, Mauro; Ventura, Laura; Senetta, Rebecca; Cassoni, Paola

    2016-01-01

    Despite several molecular signatures for “lower grade diffuse gliomas” (LGG) have been identified, WHO grade still remains a cornerstone of treatment guidelines. Mitotic count bears a crucial role in its definition, although limited by the poor reproducibility of standard Hematoxylin & Eosin (H&E) evaluation. Phospho-histone-H3 (PHH3) and Ki-67 have been proposed as alternative assays of cellular proliferation. Therefore in the present series of 141 LGG, the molecular characterization (namely IDH status, 1p/19q co-deletion and MGMT promoter methylation) was integrated with the tumor “proliferative trait” (conventional H&E or PHH3-guided mitotic count and Ki-67 index) in term of prognosis definition. Exclusively high PHH3 and Ki-67 values were predictor of poor prognosis (log rank test, P = 0.0281 for PHH3 and P = 0.032 for Ki-67), unlike standard mitotic count. Based on Cox proportional hazard regression analyses, among all clinical (age), pathological (PHH3 and Ki-67) and molecular variables (IDH, 1p/19q codeletion and MGMT methylation) with a prognostic relevance at univariate survival analysis, only IDH expression (P = 0.001) and Ki-67 proliferation index (P = 0.027) proved to be independent prognostic factors. In addition, stratifying by IDH expression status, high Ki-67 retained its prognostic relevance uniquely in the IDH negative patient (P = 0.029) doubling their risk of death (hazard ratio = 2.27). Overall, PHH3 immunostaining is the sole reliable method with a prognostic value to highlight mitotic figures in LGG. Ki-67 proliferation index exceeds PHH3 mitotic count as a predictor of patient's prognosis, and should be integrated with molecular markers in a comprehensive grading system for LGG. PMID:27049832

  9. Ki-67 proliferation index but not mitotic thresholds integrates the molecular prognostic stratification of lower grade gliomas.

    PubMed

    Duregon, Eleonora; Bertero, Luca; Pittaro, Alessandra; Soffietti, Riccardo; Rudà, Roberta; Trevisan, Morena; Papotti, Mauro; Ventura, Laura; Senetta, Rebecca; Cassoni, Paola

    2016-04-19

    Despite several molecular signatures for "lower grade diffuse gliomas" (LGG) have been identified, WHO grade still remains a cornerstone of treatment guidelines. Mitotic count bears a crucial role in its definition, although limited by the poor reproducibility of standard Hematoxylin & Eosin (H&E) evaluation. Phospho-histone-H3 (PHH3) and Ki-67 have been proposed as alternative assays of cellular proliferation. Therefore in the present series of 141 LGG, the molecular characterization (namely IDH status, 1p/19q co-deletion and MGMT promoter methylation) was integrated with the tumor "proliferative trait" (conventional H&E or PHH3-guided mitotic count and Ki-67 index) in term of prognosis definition. Exclusively high PHH3 and Ki-67 values were predictor of poor prognosis (log rank test, P = 0.0281 for PHH3 and P = 0.032 for Ki-67), unlike standard mitotic count. Based on Cox proportional hazard regression analyses, among all clinical (age), pathological (PHH3 and Ki-67) and molecular variables (IDH, 1p/19q codeletion and MGMT methylation) with a prognostic relevance at univariate survival analysis, only IDH expression (P = 0.001) and Ki-67 proliferation index (P = 0.027) proved to be independent prognostic factors. In addition, stratifying by IDH expression status, high Ki-67 retained its prognostic relevance uniquely in the IDH negative patient (P = 0.029) doubling their risk of death (hazard ratio = 2.27). Overall, PHH3 immunostaining is the sole reliable method with a prognostic value to highlight mitotic figures in LGG. Ki-67 proliferation index exceeds PHH3 mitotic count as a predictor of patient's prognosis, and should be integrated with molecular markers in a comprehensive grading system for LGG. PMID:27049832

  10. Identification of a novel mitotic phosphorylation motif associated with protein localization to the mitotic apparatus

    SciTech Connect

    Yang, Feng; Camp, David G.; Gritsenko, Marina A.; Luo, Quanzhou; Kelly, Ryan T.; Clauss, Therese RW; Brinkley, William R.; Smith, Richard D.; Stenoien, David L.

    2007-11-16

    The chromosomal passenger complex (CPC) is a critical regulator of chromosome, cytoskeleton and membrane dynamics during mitosis. Here, we identified phosphopeptides and phosphoprotein complexes recognized by a phosphorylation specific antibody that labels the CPC using liquid chromatography coupled to mass spectrometry. A mitotic phosphorylation motif (PX{G/T/S}{L/M}[pS]P or WGL[pS]P) was identified in 11 proteins including Fzr/Cdh1 and RIC-8, two proteins with potential links to the CPC. Phosphoprotein complexes contained known CPC components INCENP, Aurora-B and TD-60, as well as SMAD2, 14-3-3 proteins, PP2A, and Cdk1, a likely kinase for this motif. Protein sequence analysis identified phosphorylation motifs in additional proteins including SMAD2, Plk3 and INCENP. Mitotic SMAD2 and Plk3 phosphorylation was confirmed using phosphorylation specific antibodies, and in the case of Plk3, phosphorylation correlates with its localization to the mitotic apparatus. A mutagenesis approach was used to show INCENP phosphorylation is required for midbody localization. These results provide evidence for a shared phosphorylation event that regulates localization of critical proteins during mitosis.

  11. Cell death during crisis is mediated by mitotic telomere deprotection.

    PubMed

    Hayashi, Makoto T; Cesare, Anthony J; Rivera, Teresa; Karlseder, Jan

    2015-06-25

    Tumour formation is blocked by two barriers: replicative senescence and crisis. Senescence is triggered by short telomeres and is bypassed by disruption of tumour-suppressive pathways. After senescence bypass, cells undergo crisis, during which almost all of the cells in the population die. Cells that escape crisis harbour unstable genomes and other parameters of transformation. The mechanism of cell death during crisis remains unexplained. Here we show that human cells in crisis undergo spontaneous mitotic arrest, resulting in death during mitosis or in the following cell cycle. This phenotype is induced by loss of p53 function, and is suppressed by telomerase overexpression. Telomere fusions triggered mitotic arrest in p53-compromised non-crisis cells, indicating that such fusions are the underlying cause of cell death. Exacerbation of mitotic telomere deprotection by partial TRF2 (also known as TERF2) knockdown increased the ratio of cells that died during mitotic arrest and sensitized cancer cells to mitotic poisons. We propose a crisis pathway wherein chromosome fusions induce mitotic arrest, resulting in mitotic telomere deprotection and cell death, thereby eliminating precancerous cells from the population.

  12. The novel murine calmodulin-binding protein Sha1 disrupts mitotic spindle and replication checkpoint functions in fission yeast.

    PubMed

    Craig, R; Norbury, C

    1998-12-18

    Entry into mitosis is normally blocked in eukaryotic cells that have not completed replicative DNA synthesis; this 'S-M' checkpoint control is fundamental to the maintenance of genomic integrity. Mutants of the fission yeast Schizosaccharomyces pombe defective in the S-M checkpoint fail to arrest the cell cycle when DNA replication is inhibited and hence attempt mitosis and cell division with unreplicated chromosomes, resulting in the 'cut' phenotype. In an attempt to identify conserved molecules involved in the S-M checkpoint we have screened a regulatable murine cDNA library in S. pombe and have identified cDNAs that induce the cut phenotype in cells arrested in S phase by hydroxyurea. One such cDNA encodes a novel protein with multiple calmodulin-binding motifs that, in addition to its effects on the S-M checkpoint, perturbed mitotic spindle functions, although spindle pole duplication was apparently normal. Both aspects of the phenotype induced by this cDNA product, which we term Sha1 (for spindle and hydroxyurea checkpoint abnormal), were suppressed by simultaneous overexpression of calmodulin. Sha1 is structurally related to the product of the Drosophila gene abnormal spindle (asp). These data suggest that calmodulin-binding protein(s) are important in the co-ordination of mitotic spindle functions with mitotic entry in fission yeast, and probably also in multicellular eukaryotes. PMID:9819352

  13. Figure analysis: An implementation dialogue.

    PubMed

    Wiles, Amy M

    2016-07-01

    Figure analysis is a novel active learning teaching technique that reinforces visual literacy. Small groups of students discuss diagrams in class in order to learn content. The instructor then gives a brief introduction and later summarizes the content of the figure. This teaching technique can be used in place of lecture as a mechanism to deliver information to students. Here, a "how to" guide is presented in the form of an in-class dialogue, displaying the difficulties in visual interpretation that some students may experience while figure analysis is being implemented in an upper-level, cell biology course. Additionally, the dialogue serves as a guide for instructors who may implement the active learning technique as they consider how to respond to students' concerns in class. © 2016 by The International Union of Biochemistry and Molecular Biology, 44(4):345-348, 2016. PMID:26892173

  14. Figure analysis: An implementation dialogue.

    PubMed

    Wiles, Amy M

    2016-07-01

    Figure analysis is a novel active learning teaching technique that reinforces visual literacy. Small groups of students discuss diagrams in class in order to learn content. The instructor then gives a brief introduction and later summarizes the content of the figure. This teaching technique can be used in place of lecture as a mechanism to deliver information to students. Here, a "how to" guide is presented in the form of an in-class dialogue, displaying the difficulties in visual interpretation that some students may experience while figure analysis is being implemented in an upper-level, cell biology course. Additionally, the dialogue serves as a guide for instructors who may implement the active learning technique as they consider how to respond to students' concerns in class. © 2016 by The International Union of Biochemistry and Molecular Biology, 44(4):345-348, 2016.

  15. The Nuclear Matrix Protein Megator Regulates Stem Cell Asymmetric Division through the Mitotic Checkpoint Complex in Drosophila Testes.

    PubMed

    Liu, Ying; Singh, Shree Ram; Zeng, Xiankun; Zhao, Jiangsha; Hou, Steven X

    2015-12-01

    In adult Drosophila testis, asymmetric division of germline stem cells (GSCs) is specified by an oriented spindle and cortically localized adenomatous coli tumor suppressor homolog 2 (Apc2). However, the molecular mechanism underlying these events remains unclear. Here we identified Megator (Mtor), a nuclear matrix protein, which regulates GSC maintenance and asymmetric division through the spindle assembly checkpoint (SAC) complex. Loss of Mtor function results in Apc2 mis-localization, incorrect centrosome orientation, defective mitotic spindle formation, and abnormal chromosome segregation that lead to the eventual GSC loss. Expression of mitotic arrest-deficient-2 (Mad2) and monopolar spindle 1 (Mps1) of the SAC complex effectively rescued the GSC loss phenotype associated with loss of Mtor function. Collectively our results define a new role of the nuclear matrix-SAC axis in regulating stem cell maintenance and asymmetric division.

  16. The Nuclear Matrix Protein Megator Regulates Stem Cell Asymmetric Division through the Mitotic Checkpoint Complex in Drosophila Testes.

    PubMed

    Liu, Ying; Singh, Shree Ram; Zeng, Xiankun; Zhao, Jiangsha; Hou, Steven X

    2015-12-01

    In adult Drosophila testis, asymmetric division of germline stem cells (GSCs) is specified by an oriented spindle and cortically localized adenomatous coli tumor suppressor homolog 2 (Apc2). However, the molecular mechanism underlying these events remains unclear. Here we identified Megator (Mtor), a nuclear matrix protein, which regulates GSC maintenance and asymmetric division through the spindle assembly checkpoint (SAC) complex. Loss of Mtor function results in Apc2 mis-localization, incorrect centrosome orientation, defective mitotic spindle formation, and abnormal chromosome segregation that lead to the eventual GSC loss. Expression of mitotic arrest-deficient-2 (Mad2) and monopolar spindle 1 (Mps1) of the SAC complex effectively rescued the GSC loss phenotype associated with loss of Mtor function. Collectively our results define a new role of the nuclear matrix-SAC axis in regulating stem cell maintenance and asymmetric division. PMID:26714316

  17. Abnormal mitosis induced by wheat-rye 1R monosomic addition lines.

    PubMed

    Fu, Shu-Lan; Yang, Man-Yu; Ren, Zheng-Long; Yan, Ben-Ju; Tang, Zong-Xiang

    2014-01-01

    Octoploid triticale were derived from common wheat (Triticum aestivum L. 'Mianyang11') × rye (Secale cereale L. 'Kustro'), and some progeny were obtained by the backcrossing of triticale with 'Mianyang11' followed by self-fertilization. In situ hybridization using rye genomic DNA and repetitive sequences pAs1 and pSc119.2 as probes was used to analyze the mitotic chromosomes of these progeny. Three wheat-rye 1R monosomic addition lines and a wheat line (12FT-1685) containing a 1R and a 1BL.1RS translocation chromosome were identified. Abnormal mitosis was observed in the two lines. During mitosis of a 1R monosomic addition line (3-8-20-1R-2), lagging chromosomes, micronuclei, chromosomal bridges, and the one pole segregation of 1R chromosome were observed. Abnormal mitotic behaviour of chromosomes was also observed in some of the self-progeny plants of lines 12FT-1685 and 3-8-20-1R-2. These progeny contained 1R chromosome or 1R chromosome arm. In addition, 4B chromosomes were absent from one of the progeny of 3-8-20-1R-2. This abnormal mitotic behaviour of chromosomes was not observed in two other 1R monosomic addition lines. These results indicate that a single 1R chromosome added to wheat might cause abnormal mitotic behaviour of both wheat and rye chromosomes and different genetic variations might occurr among the sibling 1R monosomic addition lines. PMID:24564212

  18. Abnormal mitosis induced by wheat-rye 1R monosomic addition lines.

    PubMed

    Fu, Shu-Lan; Yang, Man-Yu; Ren, Zheng-Long; Yan, Ben-Ju; Tang, Zong-Xiang

    2014-01-01

    Octoploid triticale were derived from common wheat (Triticum aestivum L. 'Mianyang11') × rye (Secale cereale L. 'Kustro'), and some progeny were obtained by the backcrossing of triticale with 'Mianyang11' followed by self-fertilization. In situ hybridization using rye genomic DNA and repetitive sequences pAs1 and pSc119.2 as probes was used to analyze the mitotic chromosomes of these progeny. Three wheat-rye 1R monosomic addition lines and a wheat line (12FT-1685) containing a 1R and a 1BL.1RS translocation chromosome were identified. Abnormal mitosis was observed in the two lines. During mitosis of a 1R monosomic addition line (3-8-20-1R-2), lagging chromosomes, micronuclei, chromosomal bridges, and the one pole segregation of 1R chromosome were observed. Abnormal mitotic behaviour of chromosomes was also observed in some of the self-progeny plants of lines 12FT-1685 and 3-8-20-1R-2. These progeny contained 1R chromosome or 1R chromosome arm. In addition, 4B chromosomes were absent from one of the progeny of 3-8-20-1R-2. This abnormal mitotic behaviour of chromosomes was not observed in two other 1R monosomic addition lines. These results indicate that a single 1R chromosome added to wheat might cause abnormal mitotic behaviour of both wheat and rye chromosomes and different genetic variations might occurr among the sibling 1R monosomic addition lines.

  19. Choreography Styles in Figure Skating

    ERIC Educational Resources Information Center

    Moormann, Peter Paul

    2006-01-01

    Fifty-eight figure skating trainers from fifteen different countries acted as volunteers in this study on choreography styles. The styles were based on reports of artistic-creative strategies in composing music, drawing, writing poems or novels, and in making dances. The prevalence of the Mozartian (at the onset the choreographer already has a…

  20. Injuries in Elite Figure Skaters.

    ERIC Educational Resources Information Center

    Brock, Robert M.; Striowski, Catherine C.

    1986-01-01

    A questionnaire was used to examine the number, nature, and etiology of injuries to 60 Canadian nationally ranked figure skaters over a one-year period. Twenty-eight of the respondents reported having a significant injury during the year. Forty-three percent of the injuries were overuse injuries. (MT)

  1. Storytelling Figures: A Pueblo Tradition.

    ERIC Educational Resources Information Center

    Kraus, Nancy

    1997-01-01

    In a collaborative unit on pueblo storytelling figures involving art, music, language arts, and physical education, a teacher describes how she helped second graders understand the Pueblo pottery tradition by reading aloud literature covering the past and present. Lists folklore, fiction, poetry, nonfiction, professional resources, videos, CDs,…

  2. Haniwa Figure of a Horse.

    ERIC Educational Resources Information Center

    Park, Tad

    1988-01-01

    Presents a lesson plan which uses a "haniwa" figure of a horse to introduce K-3 students to Japanese ceramic sculpture. Includes student objectives and background information on the Kofun Period in Japan (250-552 A.D.). Presents instructional strategies, evaluation criteria, and a photograph of the sculpture. (GEA)

  3. Cell Size Modulates Oscillation, Positioning and Length of Mitotic Spindles

    PubMed Central

    Jiang, Hongyuan

    2015-01-01

    Mitotic spindle is the main subcellular structure that accomplishes the chromosome segregation between daughter cells during cell division. However, how mitotic spindles sense and control their size, position and movement inside the cell still remains unclear. In this paper, we focus on the size effects of mitotic spindles, i.e., how cell size controls various interesting phenomena in the metaphase, such as oscillation, positioning and size limit of mitotic spindles. We systematically studied the frequency doubling phenomenon during chromosome oscillation and found that cell size can regulate the period and amplitude of chromosome oscillation. We found that the relaxation time of the positioning process increases exponentially with cell size. We also showed that the stabler microtubule-kinetochore attachments alone can directly lead to an upper limit of spindle size. Our work not only explains the existing experimental observations, but also provides some interesting predictions that can be verified or rejected by further experiments. PMID:26015263

  4. The estimate on lunar figure

    NASA Astrophysics Data System (ADS)

    Gao, B. X.

    2008-10-01

    In 1799 Laplace had discovered that the lunar three principal momentum are not in equilibrium with the Moon's current orbital and rotational state.Some authors suggested that the Moon may carry a fossil figure. Before more 3 billion years the liquid Moon was closer to the Earth and revolved faster.Then the Moon migrated outwards and revolved slow down. During the early part of this migration, the Moon was continually subjected to tidal and rotational stretching and formed into an ellipsoid. Then the Moon cooled and solidified quickly. Eventually, the solid Moon's lithosphere was stable, so that we may see the very early lunar figure. In this paper, by using the lunar libration parameters and the spherical-harmonic gravity coefficient, the length of three radii a, b, c of the ellipsoid and the Moon's figure as an equilibrium tidal have been calculated. Then three conclusions can be obtained; (1) In the beginning the Moon may be very close to the Earth, before about 3 billion years the moon may cooled and solidified, and the present Moon are in the fossil figure. (2) In the third section of this paper, we demonstrate that the tidal deformation of liquid Moon was 1.934 times then the equilibrium tide. So that if to calculating the true lunar figure by using the lunar spherical-harmonic gravity coefficients, the effects of Liquid Love number hf = 1.934must be considered. (3) According to the difference between a, b, and c, the lunar distance (1.7455×108m) and spin period 3.652day can be calculated. So that the lunar orbits period was 8.34day. Hence the Moon was locked closely into a resonance orbit in the ratio 2:1 when the Moon froze.

  5. Micromechanical study of mitotic chromosome structure

    NASA Astrophysics Data System (ADS)

    Marko, John

    2011-03-01

    Our group has developed micromanipulation techniques for study of the highly compacted mitotic form of chromosome found in eukaryote cells during cell division. Each metaphase chromosome contains two duplicate centimeter-long DNA molecules, folded up by proteins into cylindrical structures several microns in length. Native chromosomes display linear and reversible stretching behavior over a wide range of extensions (up to 5x native length for amphibian chromosomes), described by a Young modulus of about 300 Pa. Studies using DNA-cutting and protein-cutting enzymes have revealed that metaphase chromosomes behave as a network of chromatin fibers held together by protein-based isolated crosslinks. Our results are not consistent with the more classical model of loops of chromatin attached to a protein-based structural organizer or ``scaffold". In short, our experiments indicate that metaphase chromosomes can be considered to be ``gels" of chromatin; the stretching modulus of a whole chromosome is consistent with stretching of the chromatin fibers contained within it. Experiments using topoisomerases suggest that topological constraints may play an appreciable role in confining chromatin in the metaphase chromosome. Finally, recent experiments on human chromosomes will be reviewed, including results of experiments where chromosome-folding proteins are specifically depleted using siRNA methods. Supported by NSF-MCB-1022117, DMR-0715099, PHY-0852130, DMR-0520513, NCI 1U54CA143869-01 (NU-PS-OC), and the American Heart Association.

  6. Imaging protein dynamics in live mitotic cells

    PubMed Central

    Ferenz, Nick P.; Ma, Nan; Lee, Wei-Lih; Wadsworth, Patricia

    2010-01-01

    To ensure that genetic material is accurately segregated during mitosis, eukaryotic cells assemble a mitotic spindle, a dynamic structure composed of microtubules and associated regulatory, structural and motor proteins. Although much has been learned in the past decades from direct observations of live cells expressing fluorescently tagged spindle proteins, a complete understanding of spindle assembly requires a detailed analysis of the dynamic behavior of component parts. Proteins tagged with conventional fluorophores, however, make such an analysis difficult because all of the molecules are uniformly fluorescent. To alleviate this problem, we have tagged proteins with a photoactivatable variant of GFP (PA-GFP), thereby allowing one to follow the behavior of a subset of tagged molecules in the cell. Here, we describe methods to tag and express proteins with PA-GFP, locally photoactivate the recombinant protein and record the dynamic behavior of the photoactivated molecules in live cells. We provide examples of photoactivable proteins in mammalian and yeast cells to illustrate the power of this approach to examine the dynamics of spindle formation and function in diverse cells. PMID:20085816

  7. Theory in Biology: Figure 1 or Figure 7?

    PubMed

    Phillips, Rob

    2015-12-01

    The pace of modern science is staggering. The quantities of data now flowing from DNA sequencers, fluorescence and electron microscopes, mass spectrometers, and other mind-blowing instruments leave us faced with information overload. This explosion in data has brought on its heels a concomitant need for efforts at the kinds of synthesis and unification we see in theoretical physics. Often in cell biology, when theoretical modeling takes place, it is as a figure 7 reflection on experiments that have already been done, with data fitting providing a metric of success. Figure 1 theory, by way of contrast, is about living dangerously by turning our thinking into formal mathematical predictions and confronting that math with experiments that have not yet been done.

  8. Theory in Biology: Figure 1 or Figure 7?

    PubMed

    Phillips, Rob

    2015-12-01

    The pace of modern science is staggering. The quantities of data now flowing from DNA sequencers, fluorescence and electron microscopes, mass spectrometers, and other mind-blowing instruments leave us faced with information overload. This explosion in data has brought on its heels a concomitant need for efforts at the kinds of synthesis and unification we see in theoretical physics. Often in cell biology, when theoretical modeling takes place, it is as a figure 7 reflection on experiments that have already been done, with data fitting providing a metric of success. Figure 1 theory, by way of contrast, is about living dangerously by turning our thinking into formal mathematical predictions and confronting that math with experiments that have not yet been done. PMID:26584768

  9. Micromechanical-biochemical studies of mitotic chromosome elasticity and structure

    NASA Astrophysics Data System (ADS)

    Poirier, Michael Guy

    The structure of mitotic chromosomes was studied by combining micromechanical force measurements with microfluidic biochemical exposures. Our method is to use glass micropipettes attached to either end of a single chromosome to do mechanical experiments in the extracellular buffer. A third pipette can be used to locally 'spray' reactants so as to carry out dynamical mechanical-chemical experiments. The following elastic properties of mitotic chromosomes are found: Young's modulus, Y = 300 Pa; Poisson ratio, sigma = 0.1; Bending rigidity, B = 1 x 10 -22 J·m; Internal viscosity, eta' = 100 kg/m·sec; Volume fraction, ϕ = 0.7; Extensions of less than 3 times the relaxed length are linear and reversible; Extensions beyond 30 fold exhibit a force plateau at 15 nN and convert the chromosome to a disperse ghost-like state with little change in chromatin structure; Mitotic chromosomes are relatively isotropic; dsDNA cuts of at least every 3 kb cause the a mitotic chromosomes to fall apart; dsDNA cuts less frequently than every 50 kb do not affect mitotic chromosome structure. These results lead to the conclusion that mitotic chromosomes are a network crosslinked every 50 kb between which chromatin is fold by chromatin folding proteins, which are likely to be condensins.

  10. Timeless links replication termination to mitotic kinase activation.

    PubMed

    Dheekollu, Jayaraju; Wiedmer, Andreas; Hayden, James; Speicher, David; Gotter, Anthony L; Yen, Tim; Lieberman, Paul M

    2011-01-01

    The mechanisms that coordinate the termination of DNA replication with progression through mitosis are not completely understood. The human Timeless protein (Tim) associates with S phase replication checkpoint proteins Claspin and Tipin, and plays an important role in maintaining replication fork stability at physical barriers, like centromeres, telomeres and ribosomal DNA repeats, as well as at termination sites. We show here that human Tim can be isolated in a complex with mitotic entry kinases CDK1, Auroras A and B, and Polo-like kinase (Plk1). Plk1 bound Tim directly and colocalized with Tim at a subset of mitotic structures in M phase. Tim depletion caused multiple mitotic defects, including the loss of sister-chromatid cohesion, loss of mitotic spindle architecture, and a failure to exit mitosis. Tim depletion caused a delay in mitotic kinase activity in vivo and in vitro, as well as a reduction in global histone H3 S10 phosphorylation during G2/M phase. Tim was also required for the recruitment of Plk1 to centromeric DNA and formation of catenated DNA structures at human centromere alpha satellite repeats. Taken together, these findings suggest that Tim coordinates mitotic kinase activation with termination of DNA replication. PMID:21573113

  11. Timeless links replication termination to mitotic kinase activation.

    PubMed

    Dheekollu, Jayaraju; Wiedmer, Andreas; Hayden, James; Speicher, David; Gotter, Anthony L; Yen, Tim; Lieberman, Paul M

    2011-05-06

    The mechanisms that coordinate the termination of DNA replication with progression through mitosis are not completely understood. The human Timeless protein (Tim) associates with S phase replication checkpoint proteins Claspin and Tipin, and plays an important role in maintaining replication fork stability at physical barriers, like centromeres, telomeres and ribosomal DNA repeats, as well as at termination sites. We show here that human Tim can be isolated in a complex with mitotic entry kinases CDK1, Auroras A and B, and Polo-like kinase (Plk1). Plk1 bound Tim directly and colocalized with Tim at a subset of mitotic structures in M phase. Tim depletion caused multiple mitotic defects, including the loss of sister-chromatid cohesion, loss of mitotic spindle architecture, and a failure to exit mitosis. Tim depletion caused a delay in mitotic kinase activity in vivo and in vitro, as well as a reduction in global histone H3 S10 phosphorylation during G2/M phase. Tim was also required for the recruitment of Plk1 to centromeric DNA and formation of catenated DNA structures at human centromere alpha satellite repeats. Taken together, these findings suggest that Tim coordinates mitotic kinase activation with termination of DNA replication.

  12. Inhibition of Bcl-xL sensitizes cells to mitotic blockers, but not mitotic drivers

    PubMed Central

    Bennett, Ailsa; Sloss, Olivia; Topham, Caroline; Nelson, Louisa; Tighe, Anthony

    2016-01-01

    Cell fate in response to an aberrant mitosis is governed by two competing networks: the spindle assembly checkpoint (SAC) and the intrinsic apoptosis pathway. The mechanistic interplay between these two networks is obscured by functional redundancy and the ability of cells to die either in mitosis or in the subsequent interphase. By coupling time-lapse microscopy with selective pharmacological agents, we systematically probe pro-survival Bcl-xL in response to various mitotic perturbations. Concentration matrices show that BH3-mimetic-mediated inhibition of Bcl-xL synergises with perturbations that induce an SAC-mediated mitotic block, including drugs that dampen microtubule dynamics, and inhibitors targeting kinesins and kinases required for spindle assembly. By contrast, Bcl-xL inhibition does not synergize with drugs which drive cells through an aberrant mitosis by overriding the SAC. This differential effect, which is explained by compensatory Mcl-1 function, provides opportunities for patient stratification and combination treatments in the context of cancer chemotherapy. PMID:27512141

  13. Therapeutic potential of mitotic interaction between the nucleoporin Tpr and aurora kinase A.

    PubMed

    Kobayashi, Akiko; Hashizume, Chieko; Dowaki, Takayuki; Wong, Richard W

    2015-01-01

    Spindle poles are defined by centrosomes; therefore, an abnormal number or defective structural organization of centrosomes can lead to loss of spindle bipolarity and genetic integrity. Previously, we showed that Tpr (translocated promoter region), a component of the nuclear pore complex (NPC), interacts with Mad1 and dynein to promote proper chromosome segregation during mitosis. Tpr also associates with p53 to induce autophagy. Here, we report that Tpr depletion induces mitotic catastrophe and enhances the rate of tetraploidy and polyploidy. Mechanistically, Tpr interacts, via its central domain, with Aurora A but not Aurora B kinase. In Tpr-depleted cells, the expression levels, centrosomal localization and phosphorylation of Aurora A were all reduced. Surprisingly, an Aurora A inhibitor, Alisertib (MLN8237), also disrupted centrosomal localization of Tpr and induced mitotic catastrophe and cell death in a time- and dose-dependent manner. Strikingly, over-expression of Aurora A disrupted Tpr centrosomal localization only in cells with supernumerary centrosomes but not in bipolar cells. Our results highlight the mutual regulation between Tpr and Aurora A and further confirm the importance of nucleoporin function in spindle pole organization, bipolar spindle assembly, and mitosis; functions that are beyond the conventional nucleocytoplasmic transport and NPC structural roles of nucleoporins. Furthermore, the central coiled-coil domain of Tpr binds to and sequesters extra Aurora A to safeguard bipolarity. This Tpr domain merits further investigation for its ability to inhibit Aurora kinase and as a potential therapeutic agent in cancer treatment.

  14. Mcl-1 dynamics influence mitotic slippage and death in mitosis

    PubMed Central

    Sloss, Olivia; Topham, Caroline; Diez, Maria; Taylor, Stephen

    2016-01-01

    Microtubule-binding drugs such as taxol are frontline treatments for a variety of cancers but exactly how they yield patient benefit is unclear. In cell culture, inhibiting microtubule dynamics prevents spindle assembly, leading to mitotic arrest followed by either apoptosis in mitosis or slippage, whereby a cell returns to interphase without dividing. Myeloid cell leukaemia-1 (Mcl-1), a pro-survival member of the Bcl-2 family central to the intrinsic apoptosis pathway, is degraded during a prolonged mitotic arrest and may therefore act as a mitotic death timer. Consistently, we show that blocking proteasome-mediated degradation inhibits taxol-induced mitotic apoptosis in a Mcl-1-dependent manner. However, this degradation does not require the activity of either APC/C-Cdc20, FBW7 or MULE, three separate E3 ubiquitin ligases implicated in targeting Mcl-1 for degradation. This therefore challenges the notion that Mcl-1 undergoes regulated degradation during mitosis. We also show that Mcl-1 is continuously synthesized during mitosis and that blocking protein synthesis accelerates taxol induced death-in-mitosis. Modulating Mcl-1 levels also influences slippage; overexpressing Mcl-1 extends the time from mitotic entry to mitotic exit in the presence of taxol, while inhibiting Mcl-1 accelerates it. We suggest that Mcl-1 competes with Cyclin B1 for binding to components of the proteolysis machinery, thereby slowing down the slow degradation of Cyclin B1 responsible for slippage. Thus, modulating Mcl-1 dynamics influences both death-in-mitosis and slippage. However, because mitotic degradation of Mcl-1 appears not to be under the control of an E3 ligase, we suggest that the notion of network crosstalk is used with caution. PMID:26769847

  15. PKCι depletion initiates mitotic slippage-induced senescence in glioblastoma.

    PubMed

    Restall, Ian J; Parolin, Doris A E; Daneshmand, Manijeh; Hanson, Jennifer E L; Simard, Manon A; Fitzpatrick, Megan E; Kumar, Ritesh; Lavictoire, Sylvie J; Lorimer, Ian A J

    2015-01-01

    Cellular senescence is a tumor suppressor mechanism where cells enter a permanent growth arrest following cellular stress. Oncogene-induced senescence (OIS) is induced in non-malignant cells following the expression of an oncogene or inactivation of a tumor suppressor. Previously, we have shown that protein kinase C iota (PKCι) depletion induces cellular senescence in glioblastoma cells in the absence of a detectable DNA damage response. Here we demonstrate that senescent glioblastoma cells exhibit an aberrant centrosome morphology. This was observed in basal levels of senescence, in p21-induced senescence, and in PKCι depletion-induced senescence. In addition, senescent glioblastoma cells are polyploid, Ki-67 negative and arrest at the G1/S checkpoint, as determined by expression of cell cycle regulatory proteins. These markers are all consistent with cells that have undergone mitotic slippage. Failure of the spindle assembly checkpoint to function properly can lead to mitotic slippage, resulting in the premature exit of mitotic cells into the G1 phase of the cell cycle. Although in G1, these cells have the replicated DNA and centrosomal phenotype of a cell that has entered mitosis and failed to divide. Overall, we demonstrate that PKCι depletion initiates mitotic slippage-induced senescence in glioblastoma cells. To our knowledge, this is the first evidence of markers of mitotic slippage directly in senescent cells by co-staining for senescence-associated β-galactosidase and immunofluorescence markers in the same cell population. We suggest that markers of mitotic slippage be assessed in future studies of senescence to determine the extent of mitotic slippage in the induction of cellular senescence. PMID:26208522

  16. Mice produced by mitotic reprogramming of sperm injected into haploid parthenogenotes

    PubMed Central

    Suzuki, Toru; Asami, Maki; Hoffmann, Martin; Lu, Xin; Gužvić, Miodrag; Klein, Christoph A.; Perry, Anthony C. F.

    2016-01-01

    Sperm are highly differentiated and the activities that reprogram them for embryonic development during fertilization have historically been considered unique to the oocyte. We here challenge this view and demonstrate that mouse embryos in the mitotic cell cycle can also directly reprogram sperm for full-term development. Developmentally incompetent haploid embryos (parthenogenotes) injected with sperm developed to produce healthy offspring at up to 24% of control rates, depending when in the embryonic cell cycle injection took place. This implies that most of the first embryonic cell cycle can be bypassed in sperm genome reprogramming for full development. Remodelling of histones and genomic 5′-methylcytosine and 5′-hydroxymethylcytosine following embryo injection were distinct from remodelling in fertilization and the resulting 2-cell embryos consistently possessed abnormal transcriptomes. These studies demonstrate plasticity in the reprogramming of terminally differentiated sperm nuclei and suggest that different epigenetic pathways or kinetics can establish totipotency. PMID:27623537

  17. Mice produced by mitotic reprogramming of sperm injected into haploid parthenogenotes.

    PubMed

    Suzuki, Toru; Asami, Maki; Hoffmann, Martin; Lu, Xin; Gužvić, Miodrag; Klein, Christoph A; Perry, Anthony C F

    2016-01-01

    Sperm are highly differentiated and the activities that reprogram them for embryonic development during fertilization have historically been considered unique to the oocyte. We here challenge this view and demonstrate that mouse embryos in the mitotic cell cycle can also directly reprogram sperm for full-term development. Developmentally incompetent haploid embryos (parthenogenotes) injected with sperm developed to produce healthy offspring at up to 24% of control rates, depending when in the embryonic cell cycle injection took place. This implies that most of the first embryonic cell cycle can be bypassed in sperm genome reprogramming for full development. Remodelling of histones and genomic 5'-methylcytosine and 5'-hydroxymethylcytosine following embryo injection were distinct from remodelling in fertilization and the resulting 2-cell embryos consistently possessed abnormal transcriptomes. These studies demonstrate plasticity in the reprogramming of terminally differentiated sperm nuclei and suggest that different epigenetic pathways or kinetics can establish totipotency. PMID:27623537

  18. Mitotic Exit Control as an Evolved Complex System

    SciTech Connect

    Bosl, W; Li, R

    2005-04-25

    The exit from mitosis is the last critical decision a cell has to make during a division cycle. A complex regulatory system has evolved to evaluate the success of mitotic events and control this decision. Whereas outstanding genetic work in yeast has led to rapid discovery of a large number of interacting genes involved in the control of mitotic exit, it has also become increasingly difficult to comprehend the logic and mechanistic features embedded in the complex molecular network. Our view is that this difficulty stems in part from the attempt to explain mitotic exit control using concepts from traditional top-down engineering design, and that exciting new results from evolutionary engineering design applied to networks and electronic circuits may lend better insights. We focus on four particularly intriguing features of the mitotic exit control system: the two-stepped release of Cdc14; the self-activating nature of Tem1 GTPase; the spatial sensor associated with the spindle pole body; and the extensive redundancy in the mitotic exit network. We attempt to examine these design features from the perspective of evolutionary design and complex system engineering.

  19. Mechanical control of mitotic progression in single animal cells.

    PubMed

    Cattin, Cedric J; Düggelin, Marcel; Martinez-Martin, David; Gerber, Christoph; Müller, Daniel J; Stewart, Martin P

    2015-09-01

    Despite the importance of mitotic cell rounding in tissue development and cell proliferation, there remains a paucity of approaches to investigate the mechanical robustness of cell rounding. Here we introduce ion beam-sculpted microcantilevers that enable precise force-feedback-controlled confinement of single cells while characterizing their progression through mitosis. We identify three force regimes according to the cell response: small forces (∼5 nN) that accelerate mitotic progression, intermediate forces where cells resist confinement (50-100 nN), and yield forces (>100 nN) where a significant decline in cell height impinges on microtubule spindle function, thereby inhibiting mitotic progression. Yield forces are coincident with a nonlinear drop in cell height potentiated by persistent blebbing and loss of cortical F-actin homogeneity. Our results suggest that a buildup of actomyosin-dependent cortical tension and intracellular pressure precedes mechanical failure, or herniation, of the cell cortex at the yield force. Thus, we reveal how the mechanical properties of mitotic cells and their response to external forces are linked to mitotic progression under conditions of mechanical confinement.

  20. Loops determine the mechanical properties of mitotic chromosomes

    NASA Astrophysics Data System (ADS)

    Zhang, Yang; Heermann, Dieter W.

    2013-03-01

    In mitosis, chromosomes undergo a condensation into highly compacted, rod-like objects. Many models have been put forward for the higher-order organization of mitotic chromosomes including radial loop and hierarchical folding models. Additionally, mechanical properties of mitotic chromosomes under different conditions were measured. However, the internal organization of mitotic chromosomes still remains unclear. Here we present a polymer model for mitotic chromosomes and show how chromatin loops play a major role for their mechanical properties. The key assumption of the model is the ability of the chromatin fibre to dynamically form loops with the help of binding proteins. Our results show that looping leads to a tight compaction and significantly increases the bending rigidity of chromosomes. Moreover, our qualitative prediction of the force elongation behaviour is close to experimental findings. This indicates that the internal structure of mitotic chromosomes is based on self-organization of the chromatin fibre. We also demonstrate how number and size of loops have a strong influence on the mechanical properties. We suggest that changes in the mechanical characteristics of chromosomes can be explained by an altered internal loop structure. YZ gratefully appreciates funding by the German National Academic Foundation (Studienstiftung des deutschen Volkes) and support by the Heidelberg Graduate School for Mathematical and Computational Methods in the Sciences (HGS MathComp).

  1. Developmental abnormalities of the gonad and abnormal sex hormone concentrations in juvenile alligators from contaminated and control lakes in Florida.

    PubMed Central

    Guillette, L J; Gross, T S; Masson, G R; Matter, J M; Percival, H F; Woodward, A R

    1994-01-01

    The reproductive development of alligators from a contaminated and a control lake in central Florida was examined. Lake Apopka is adjacent to an EPA Superfund site, listed due to an extensive spill of dicofol and DDT or its metabolites. These compounds can act as estrogens. Contaminants in the lake also have been derived from extensive agricultural activities around the lake that continue today and a sewage treatment facility associated with the city of Winter Garden, Florida. We examined the hypothesis that an estrogenic contaminant has caused the current failure in recruitment of alligators on Lake Apopka. Supporting data include the following: At 6 months of age, female alligators from Lake Apopka had plasma estradiol-17 beta concentrations almost two times greater than normal females from the control lake, Lake Woodruff. The Apopka females exhibited abnormal ovarian morphology with large numbers of polyovular follicles and polynuclear oocytes. Male juvenile alligators had significantly depressed plasma testosterone concentrations comparable to levels observed in normal Lake Woodruff females but more than three times lower than normal Lake Woodruff males. Additionally, males from Lake Apopka had poorly organized testes and abnormally small phalli. The differences between lakes and sexes in plasma hormone concentrations of juvenile alligators remain even after stimulation with luteinizing hormone. Our data suggest that the gonads of juveniles from Lake Apopka have been permanently modified in ovo, so that normal steroidogenesis is not possible, and thus normal sexual maturation is unlikely. Images p680-a Figure 1. Figure 2. Figure 3. A Figure 3. B Figure 3. C Figure 4. A Figure 4. B Figure 4. C Figure 4. D Figure 5. A Figure 5. B Figure 5. C PMID:7895709

  2. Enhanced spatial resolution on figures versus grounds.

    PubMed

    Hecht, Lauren N; Cosman, Joshua D; Vecera, Shaun P

    2016-07-01

    Much is known about the cues that determine figure-ground assignment, but less is known about the consequences of figure-ground assignment on later visual processing. Previous work has demonstrated that regions assigned figural status are subjectively more shape-like and salient than background regions. The increase in subjective salience of figural regions could be caused by a number of processes, one of which may be enhanced perceptual processing (e.g., an enhanced neural representation) of figures relative to grounds. We explored this hypothesis by having observers perform a perceptually demanding spatial resolution task in which targets appeared on either figure or ground regions. To rule out a purely attentional account of figural salience, observers discriminated targets on the basis of a region's color (red or green), which was equally likely to define the figure or the ground. The results of our experiments showed that targets appearing on figures were discriminated more accurately than those appearing in ground regions. In addition, targets appearing on figures were discriminated better than those presented in regions considered figurally neutral, but targets appearing within ground regions were discriminated more poorly than those appearing in figurally neutral regions. Taken together, our findings suggest that when two regions share a contour, regions assigned as figure are perceptually enhanced, whereas regions assigned as ground are perceptually suppressed. PMID:27048441

  3. Shaping mitotic chromosomes: From classical concepts to molecular mechanisms

    PubMed Central

    Kschonsak, Marc; Haering, Christian H

    2015-01-01

    How eukaryotic genomes are packaged into compact cylindrical chromosomes in preparation for cell divisions has remained one of the major unsolved questions of cell biology. Novel approaches to study the topology of DNA helices inside the nuclei of intact cells, paired with computational modeling and precise biomechanical measurements of isolated chromosomes, have advanced our understanding of mitotic chromosome architecture. In this Review Essay, we discuss – in light of these recent insights – the role of chromatin architecture and the functions and possible mechanisms of SMC protein complexes and other molecular machines in the formation of mitotic chromosomes. Based on the information available, we propose a stepwise model of mitotic chromosome condensation that envisions the sequential generation of intra-chromosomal linkages by condensin complexes in the context of cohesin-mediated inter-chromosomal linkages, assisted by topoisomerase II. The described scenario results in rod-shaped metaphase chromosomes ready for their segregation to the cell poles. PMID:25988527

  4. Shaping mitotic chromosomes: From classical concepts to molecular mechanisms.

    PubMed

    Kschonsak, Marc; Haering, Christian H

    2015-07-01

    How eukaryotic genomes are packaged into compact cylindrical chromosomes in preparation for cell divisions has remained one of the major unsolved questions of cell biology. Novel approaches to study the topology of DNA helices inside the nuclei of intact cells, paired with computational modeling and precise biomechanical measurements of isolated chromosomes, have advanced our understanding of mitotic chromosome architecture. In this Review Essay, we discuss - in light of these recent insights - the role of chromatin architecture and the functions and possible mechanisms of SMC protein complexes and other molecular machines in the formation of mitotic chromosomes. Based on the information available, we propose a stepwise model of mitotic chromosome condensation that envisions the sequential generation of intra-chromosomal linkages by condensin complexes in the context of cohesin-mediated inter-chromosomal linkages, assisted by topoisomerase II. The described scenario results in rod-shaped metaphase chromosomes ready for their segregation to the cell poles.

  5. Hooke's figurations: a figural drawing attributed to Robert Hooke.

    PubMed

    Hunter, Matthew C

    2010-09-20

    The experimental philosopher Robert Hooke (1635-1703) is known to have apprenticed to the leading painter Peter Lely on his first arrival in London in the late 1640s. Yet the relevance of Hooke's artistic training to his mature draughtsmanship and identity has remained unclear. Shedding light on that larger interpretive problem, this article argues for the attribution to Hooke of a figural drawing now in Tate Britain (T10678). This attributed drawing is especially interesting because it depicts human subjects and bears Hooke's name functioning as an artistic signature, both highly unusual features for his draughtsmanship. From evidence of how this drawing was collected and physically placed alongside images by leading artists in the early eighteenth century, I suggest how it can offer new insight into the reception of Hooke and his graphic work in the early Enlightenment. PMID:20973449

  6. Hooke's figurations: a figural drawing attributed to Robert Hooke.

    PubMed

    Hunter, Matthew C

    2010-09-20

    The experimental philosopher Robert Hooke (1635-1703) is known to have apprenticed to the leading painter Peter Lely on his first arrival in London in the late 1640s. Yet the relevance of Hooke's artistic training to his mature draughtsmanship and identity has remained unclear. Shedding light on that larger interpretive problem, this article argues for the attribution to Hooke of a figural drawing now in Tate Britain (T10678). This attributed drawing is especially interesting because it depicts human subjects and bears Hooke's name functioning as an artistic signature, both highly unusual features for his draughtsmanship. From evidence of how this drawing was collected and physically placed alongside images by leading artists in the early eighteenth century, I suggest how it can offer new insight into the reception of Hooke and his graphic work in the early Enlightenment.

  7. Single-walled carbon nanotube-induced mitotic disruption⋆

    PubMed Central

    Sargent, L.M.; Hubbs, A.F.; Young, S.-H.; Kashon, M.L.; Dinu, C.Z.; Salisbury, J.L.; Benkovic, S.A.; Lowry, D.T.; Murray, A.R.; Kisin, E.R.; Siegrist, K.J.; Battelli, L.; Mastovich, J.; Sturgeon, J.L.; Bunker, K.L.; Shvedova, A.A.; Reynolds, S.H.

    2015-01-01

    Carbon nanotubes were among the earliest products of nanotechnology and have many potential applications in medicine, electronics, and manufacturing. The low density, small size, and biological persistence of carbon nanotubes create challenges for exposure control and monitoring and make respiratory exposures to workers likely. We have previously shown mitotic spindle aberrations in cultured primary and immortalized human airway epithelial cells exposed to 24, 48 and 96 μg/cm2 single-walled carbon nanotubes (SWCNT). To investigate mitotic spindle aberrations at concentrations anticipated in exposed workers, primary and immortalized human airway epithelial cells were exposed to SWCNT for 24–72 h at doses equivalent to 20 weeks of exposure at the Permissible Exposure Limit for particulates not otherwise regulated. We have now demonstrated fragmented centrosomes, disrupted mitotic spindles and aneuploid chromosome number at those doses. The data further demonstrated multipolar mitotic spindles comprised 95% of the disrupted mitoses. The increased multipolar mitotic spindles were associated with an increased number of cells in the G2 phase of mitosis, indicating a mitotic checkpoint response. Nanotubes were observed in association with mitotic spindle microtubules, the centrosomes and condensed chromatin in cells exposed to 0.024, 0.24, 2.4 and 24 μg/cm2 SWCNT. Three-dimensional reconstructions showed carbon nanotubes within the centrosome structure. The lower doses did not cause cytotoxicity or reduction in colony formation after 24 h; however, after three days, significant cytotoxicity was observed in the SWCNT-exposed cells. Colony formation assays showed an increased proliferation seven days after exposure. Our results show significant disruption of the mitotic spindle by SWCNT at occupationally relevant doses. The increased proliferation that was observed in carbon nanotube-exposed cells indicates a greater potential to pass the genetic damage to daughter

  8. 49 CFR Appendix - Figures to Part 38

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 1 2013-10-01 2013-10-01 false Figures to Part 38 Transportation Office of the Secretary of Transportation AMERICANS WITH DISABILITIES ACT (ADA) ACCESSIBILITY SPECIFICATIONS FOR TRANSPORTATION VEHICLES Other Vehicles and Systems Trams, and similar vehicles, and systems Pt. 38, Figures Figures to Part 38 ER28SE98.000...

  9. 49 CFR Appendix - Figures to Part 38

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 1 2012-10-01 2012-10-01 false Figures to Part 38 Transportation Office of the Secretary of Transportation AMERICANS WITH DISABILITIES ACT (ADA) ACCESSIBILITY SPECIFICATIONS FOR TRANSPORTATION VEHICLES Other Vehicles and Systems Trams, and similar vehicles, and systems Pt. 38, Figures Figures to Part 38 ER28SE98.000...

  10. 49 CFR Appendix - Figures to Part 38

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 1 2011-10-01 2011-10-01 false Figures to Part 38 Transportation Office of the Secretary of Transportation AMERICANS WITH DISABILITIES ACT (ADA) ACCESSIBILITY SPECIFICATIONS FOR TRANSPORTATION VEHICLES Other Vehicles and Systems Trams, and similar vehicles, and systems Pt. 38, Figures Figures to Part 38 ER28SE98.000...

  11. 49 CFR Appendix - Figures to Part 38

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 1 2010-10-01 2010-10-01 false Figures to Part 38 Transportation Office of the Secretary of Transportation AMERICANS WITH DISABILITIES ACT (ADA) ACCESSIBILITY SPECIFICATIONS FOR TRANSPORTATION VEHICLES Other Vehicles and Systems Trams, and similar vehicles, and systems Pt. 38, Figures Figures to Part 38 ER28SE98.000...

  12. PHOBOS Experiment: Figures and Data

    DOE Data Explorer

    The PHOBOS Collaboration

    PHOBOS consists of many silicon detectors surrounding the interaction region. With these detectors physicists can count the total number of produced particles and study the angular distributions of all the products. Physicists know from other branches of physics that a characteristic of phase transitions are fluctuations in physical observables. With the PHOBOS array they look for unusual events or fluctuations in the number of particles and angular distribution. The articles that have appeared in refereed science journals are listed here with separate links to the supporting data plots, figures, and tables of numeric data.  See also supporting data for articles in technical journals at http://www.phobos.bnl.gov/Publications/Technical/phobos_technical_publications.htm and from conference proceedings at http://www.phobos.bnl.gov/Publications/Proceedings/phobos_proceedings_publications.htm

  13. Brainhood, anthropological figure of modernity.

    PubMed

    Vidal, Fernando

    2009-02-01

    If personhood is the quality or condition of being an individual person, "brainhood" could name the quality or condition of being a brain. This ontological quality would define the "cerebral subject" that has, at least in industrialized and highly medicalized societies, gained numerous social inscriptions since the mid-20th century. This article explores the historical development of brainhood. It suggests that the brain is necessarily the location of the "modern self," and that, consequently, the cerebral subject is the anthropological figure inherent to modernity (at least insofar as modernity gives supreme value to the individual as autonomous agent of choice and initiative). It further argues that the ideology of brainhood impelled neuroscientific investigation much more than it resulted from it, and sketches how an expanding constellation of neurocultural discourses and practices embodies and sustains that ideology.

  14. The budding yeast nuclear envelope adjacent to the nucleolus serves as a membrane sink during mitotic delay.

    PubMed

    Witkin, Keren L; Chong, Yolanda; Shao, Sichen; Webster, Micah T; Lahiri, Sujoy; Walters, Alison D; Lee, Brandon; Koh, Judice L Y; Prinz, William A; Andrews, Brenda J; Cohen-Fix, Orna

    2012-06-19

    The mechanisms that dictate nuclear shape are largely unknown. Here we screened the budding yeast deletion collection for mutants with abnormal nuclear shape. A common phenotype was the appearance of a nuclear extension, particularly in mutants in DNA repair and chromosome segregation genes. Our data suggest that these mutations led to the abnormal nuclear morphology indirectly, by causing a checkpoint-induced cell-cycle delay. Indeed, delaying cells in mitosis by other means also led to the appearance of nuclear extensions, whereas inactivating the DNA damage checkpoint pathway in a DNA repair mutant reduced the fraction of cells with nuclear extensions. Formation of a nuclear extension was specific to a mitotic delay, because cells arrested in S or G2 had round nuclei. Moreover, the nuclear extension always coincided with the nucleolus, while the morphology of the DNA mass remained largely unchanged. Finally, we found that phospholipid synthesis continued unperturbed when cells delayed in mitosis, and inhibiting phospholipid synthesis abolished the formation of nuclear extensions. Our data suggest a mechanism that promotes nuclear envelope expansion during mitosis. When mitotic progression is delayed, cells sequester the added membrane to the nuclear envelope associated with the nucleolus, possibly to avoid disruption of intranuclear organization.

  15. Tooth - abnormal shape

    MedlinePlus

    Hutchinson incisors; Abnormal tooth shape; Peg teeth; Mulberry teeth; Conical teeth ... The appearance of normal teeth varies, especially the molars. ... conditions. Specific diseases can affect tooth shape, tooth ...

  16. Reconstitution of Basic Mitotic Spindles in Spherical Emulsion Droplets.

    PubMed

    Vleugel, Mathijs; Roth, Sophie; Groenendijk, Celebrity F; Dogterom, Marileen

    2016-01-01

    Mitotic spindle assembly, positioning and orientation depend on the combined forces generated by microtubule dynamics, microtubule motor proteins and cross-linkers. Growing microtubules can generate pushing forces, while depolymerizing microtubules can convert the energy from microtubule shrinkage into pulling forces, when attached, for example, to cortical dynein or chromosomes. In addition, motor proteins and diffusible cross-linkers within the spindle contribute to spindle architecture by connecting and sliding anti-parallel microtubules. In vivo, it has proven difficult to unravel the relative contribution of individual players to the overall balance of forces. Here we present the methods that we recently developed in our efforts to reconstitute basic mitotic spindles bottom-up in vitro. Using microfluidic techniques, centrosomes and tubulin are encapsulated in water-in-oil emulsion droplets, leading to the formation of geometrically confined (double) microtubule asters. By additionally introducing cortically anchored dynein, plus-end directed microtubule motors and diffusible cross-linkers, this system is used to reconstitute spindle-like structures. The methods presented here provide a starting point for reconstitution of more complete mitotic spindles, allowing for a detailed study of the contribution of each individual component, and for obtaining an integrated quantitative view of the force-balance within the mitotic spindle. PMID:27584979

  17. Dynamical modeling of syncytial mitotic cycles in Drosophila embryos

    PubMed Central

    Calzone, Laurence; Thieffry, Denis; Tyson, John J; Novak, Bela

    2007-01-01

    Immediately following fertilization, the fruit fly embryo undergoes 13 rapid, synchronous, syncytial nuclear division cycles driven by maternal genes and proteins. During these mitotic cycles, there are barely detectable oscillations in the total level of B-type cyclins. In this paper, we propose a dynamical model for the molecular events underlying these early nuclear division cycles in Drosophila. The model distinguishes nuclear and cytoplasmic compartments of the embryo and permits exploration of a variety of rules for protein transport between the compartments. Numerical simulations reproduce the main features of wild-type mitotic cycles: patterns of protein accumulation and degradation, lengthening of later cycles, and arrest in interphase 14. The model is consistent with mutations that introduce subtle changes in the number of mitotic cycles before interphase arrest. Bifurcation analysis of the differential equations reveals the dependence of mitotic oscillations on cycle number, and how this dependence is altered by mutations. The model can be used to predict the phenotypes of novel mutations and effective ranges of the unmeasured rate constants and transport coefficients in the proposed mechanism. PMID:17667953

  18. Mitotic lamin disassembly is triggered by lipid-mediated signaling.

    PubMed

    Mall, Moritz; Walter, Thomas; Gorjánácz, Mátyás; Davidson, Iain F; Nga Ly-Hartig, Thi Bach; Ellenberg, Jan; Mattaj, Iain W

    2012-09-17

    Disassembly of the nuclear lamina is a key step during open mitosis in higher eukaryotes. The activity of several kinases, including CDK1 (cyclin-dependent kinase 1) and protein kinase C (PKC), has been shown to trigger mitotic lamin disassembly, yet their precise contributions are unclear. In this study, we develop a quantitative imaging assay to study mitotic lamin B1 disassembly in living cells. We find that CDK1 and PKC act in concert to mediate phosphorylation-dependent lamin B1 disassembly during mitosis. Using ribonucleic acid interference (RNAi), we showed that diacylglycerol (DAG)-dependent PKCs triggered rate-limiting steps of lamin disassembly. RNAi-mediated depletion or chemical inhibition of lipins, enzymes that produce DAG, delayed lamin disassembly to a similar extent as does PKC inhibition/depletion. Furthermore, the delay of lamin B1 disassembly after lipin depletion could be rescued by the addition of DAG. These findings suggest that lipins activate a PKC-dependent pathway during mitotic lamin disassembly and provide evidence for a lipid-mediated mitotic signaling event.

  19. Tumor suppressor VHL functions in the control of mitotic fidelity.

    PubMed

    Hell, Michael P; Duda, Maria; Weber, Thomas C; Moch, Holger; Krek, Wilhelm

    2014-05-01

    The von Hippel-Lindau (VHL) tumor suppressor protein pVHL is commonly mutated in clear cell renal cell carcinoma (ccRCC) and has been implicated in the control of multiple cellular processes that might be linked to tumor suppression, including promoting proper spindle orientation and chromosomal stability. However, it is unclear whether pVHL exerts these mitotic regulatory functions in vivo as well. Here, we applied ischemic kidney injury to stimulate cell division in otherwise quiescent mouse adult kidneys. We show that in the short term (5.5 days after surgery), Vhl-deficient kidney cells demonstrate both spindle misorientation and aneuploidy. The spindle misorientation phenotype encompassed changes in directed cell division, which may manifest in the development of cystic lesions, whereas the aneuploidy phenotype involved the occurrence of lagging chromosomes but not chromosome bridges, indicative of mitotic checkpoint impairment. Intriguingly, in the long term (4 months after the ischemic insult), Vhl-deficient kidneys displayed a heterogeneous pattern of ccRCC precursor lesions, including cysts, clear cell-type cells, and dysplasia. Together, these data provide direct evidence for a key role of pVHL in mediating oriented cell division and faithful mitotic checkpoint function in the renal epithelium, emphasizing the importance of pVHL as a controller of mitotic fidelity in vivo.

  20. Modelling the mitotic apparatus. From the discovery of the bipolar spindle to modern concepts.

    PubMed

    Gourret, J P

    1995-06-01

    This bibliographical review of the modelling of the mitotic apparatus covers a period of one hundred and twenty years, from the discovery of the bipolar mitotic spindle up to the present day. Without attempting to be fully comprehensive, it will describe the evolution of the main ideas that have left their mark on a century of experimental and theoretical research. Fol and Bütschli's first writings date back to 1873, at a time when Schleiden and Schwann's cell theory was rapidly gaining ground throughout Germany. Both mitosis and chromosomes were to be discovered within the space of thirty years, along with the two key events in the animal and plant reproductive cycle, namely fecondation and meiosis. The mitotic pole, a term still in use to this day, was employed to describe a morphological fact which was noted as early as 1876, namely that the lines and the dots of the karyokinetic figure, with its spindle and asters, looks remarkably like the lines of force around a bar magnet. This was to lead to models designed to explain the movements of chromosomes which take place when the cell nucleus appears to cease to exist as an organelle during mitosis. The nature of those mechanisms and the origin of the forces behind the chromosomes' ordered movements were central to the debate. Auguste Prenant, in a remarkable bibliographical synthesis published in 1910, summed up the opposing viewpoints of the 'vitalists', on the one hand, who favoured the theory of contractility or extensility in spindle fibres, and of those who believed in models based on physical phenomena, on the other. The latter subdivided into two groups: some, like Bütschli, Rhumbler or Leduc, referred to diffusion, osmosis and superficial tension, whilst the others, led by Gallardo and Hartog, focussed on the laws of electromagnetism. Lillie, Kuwada and Darlington followed up this line of research. The mid-20th century was a major turning point. Most of the modelling mentioned above was criticized and

  1. Cytotoxic effects of cylindrospermopsin in mitotic and non-mitotic Vicia faba cells.

    PubMed

    Garda, Tamás; Riba, Milán; Vasas, Gábor; Beyer, Dániel; M-Hamvas, Márta; Hajdu, Gréta; Tándor, Ildikó; Máthé, Csaba

    2015-02-01

    Cylindrospermopsin (CYN) is a cyanobacterial toxin known as a eukaryotic protein synthesis inhibitor. We aimed to study its effects on growth, stress responses and mitosis of a eukaryotic model, Vicia faba (broad bean). Growth responses depended on exposure time (3 or 6d), cyanotoxin concentration, culture conditions (dark or continuous light) and V. faba cultivar ("Standard" or "ARC Egypt Cross"). At 6d of exposure, CYN had a transient stimulatory effect on root system growth, roots being possibly capable of detoxification. The toxin induced nucleus fragmentation, blebbing and chromosomal breaks indicating double stranded DNA breaks and programmed cell death. Root necrotic tissue was observed at 0.1-20 μg mL(-1) CYN that probably impeded toxin uptake into vascular tissue. Growth and cell death processes observed were general stress responses. In lateral root tip meristems, lower CYN concentrations (0.01-0.1 μg mL(-1)) induced the stimulation of mitosis and distinct mitotic phases, irrespective of culture conditions or the cultivar used. Higher cyanotoxin concentrations inhibited mitosis. Short-term exposure of hydroxylurea-synchronized roots to 5 μg mL(-1) CYN induced delay of mitosis that might have been related to a delay of de novo protein synthesis. CYN induced the formation of double, split and asymmetric preprophase bands (PPBs), in parallel with the alteration of cell division planes, related to the interference of cyanotoxin with protein synthesis, thus it was a plant- and CYN specific alteration.

  2. Mechanism of APC/CCDC20 activation by mitotic phosphorylation

    PubMed Central

    Qiao, Renping; Weissmann, Florian; Yamaguchi, Masaya; Brown, Nicholas G.; VanderLinden, Ryan; Imre, Richard; Jarvis, Marc A.; Brunner, Michael R.; Davidson, Iain F.; Litos, Gabriele; Haselbach, David; Mechtler, Karl; Stark, Holger; Schulman, Brenda A.; Peters, Jan-Michael

    2016-01-01

    Chromosome segregation and mitotic exit are initiated by the 1.2-MDa ubiquitin ligase APC/C (anaphase-promoting complex/cyclosome) and its coactivator CDC20 (cell division cycle 20). To avoid chromosome missegregation, APC/CCDC20 activation is tightly controlled. CDC20 only associates with APC/C in mitosis when APC/C has become phosphorylated and is further inhibited by a mitotic checkpoint complex until all chromosomes are bioriented on the spindle. APC/C contains 14 different types of subunits, most of which are phosphorylated in mitosis on multiple sites. However, it is unknown which of these phospho-sites enable APC/CCDC20 activation and by which mechanism. Here we have identified 68 evolutionarily conserved mitotic phospho-sites on human APC/C bound to CDC20 and have used the biGBac technique to generate 47 APC/C mutants in which either all 68 sites or subsets of them were replaced by nonphosphorylatable or phospho-mimicking residues. The characterization of these complexes in substrate ubiquitination and degradation assays indicates that phosphorylation of an N-terminal loop region in APC1 is sufficient for binding and activation of APC/C by CDC20. Deletion of the N-terminal APC1 loop enables APC/CCDC20 activation in the absence of mitotic phosphorylation or phospho-mimicking mutations. These results indicate that binding of CDC20 to APC/C is normally prevented by an autoinhibitory loop in APC1 and that its mitotic phosphorylation relieves this inhibition. The predicted location of the N-terminal APC1 loop implies that this loop controls interactions between the N-terminal domain of CDC20 and APC1 and APC8. These results reveal how APC/C phosphorylation enables CDC20 to bind and activate the APC/C in mitosis. PMID:27114510

  3. Structurally abnormal human autosomes

    SciTech Connect

    1993-12-31

    Chapter 25, discusses structurally abnormal human autosomes. This discussion includes: structurally abnormal chromosomes, chromosomal polymorphisms, pericentric inversions, paracentric inversions, deletions or partial monosomies, cri du chat (cat cry) syndrome, ring chromosomes, insertions, duplication or pure partial trisomy and mosaicism. 71 refs., 8 figs.

  4. Morphological abnormalities among lampreys

    USGS Publications Warehouse

    Manion, Patrick J.

    1967-01-01

    The experimental control of the sea lamprey (Petromyzon marinus) in the Great Lakes has required the collection of thousands of lampreys. Representatives of each life stage of the four species of the Lake Superior basin were examined for structural abnormalities. The most common aberration was the presence of additional tails. The accessory tails were always postanal and smaller than the normal tail. The point of origin varied; the extra tails occurred on dorsal, ventral, or lateral surfaces. Some of the extra tails were misshaped and curled, but others were normal in shape and pigment pattern. Other abnormalities in larval sea lampreys were malformed or twisted tails and bodies. The cause of the structural abnormalities is unknown. The presence of extra caudal fins could be genetically controlled, or be due to partial amputation or injury followed by abnormal regeneration. Few if any lampreys with structural abnormalities live to sexual maturity.

  5. Misregulation of mitotic chromosome segregation in a new type of autosomal recessive primary microcephaly.

    PubMed

    Marchal, Juan Alberto; Ghani, Mahdi; Schindler, Detlev; Gavvovidis, Ioannis; Winkler, Tina; Esquitino, Veronique; Sternberg, Nadine; Busche, Andreas; Krawitz, Peter; Hecht, Joachim; Robinson, Peter; Mundlos, Stephan; Graul-Neumann, Luitgard; Sperling, Karl; Trimborn, Marc; Neitzel, Heidemarie

    2011-09-01

    Primary autosomal recessive microcephaly (MCPH) is a congenital disorder characterized by a pronounced reduction of brain size and mental retardation. We present here a consanguineous Turkish family clinically diagnosed with MCPH and without linkage to any of the known loci (MCPH1-MCPH7). Autozygosity mapping identified a homozygous region of 15.8 Mb on chromosome 10q11.23-21.3, most likely representing a new locus for MCPH. Although we were unable to identify the underlying genetic defect after extensive molecular screening, we could delineate a possible molecular function in chromosome segregation by the characterization of mitosis in the patients' cells. Analyses of chromosome nondisjunction in T-lymphocytes and fibroblasts revealed a significantly elevated rate of nondisjunction in the patients' cells as compared to controls. Mitotic progression was further explored by immunofluorescence analyses of several chromosome and spindle associated proteins. We detected a remarkable alteration in the anaphase distribution of Aurora B and INCENP, which are key regulators of chromosome segregation. In particular, a fraction of both proteins remained abnormally loaded on chromosomes during anaphase in MCPH patients' cells while in cells of normal control subjects both proteins are completely transferred to the spindle midzone. We did not observe any other alterations regarding cell cycle progression, chromosome structure, or response to DNA damage. Our observations point towards a molecular role of the underlying gene product in the regulation of anaphase/telophase progression possibly through interaction with chromosomal passenger proteins. In addition, our findings represent further evidence for the proposed role of MCPH genes in the regulation of mitotic progression.

  6. Recommended reference figures for geophysics and geodesy

    NASA Technical Reports Server (NTRS)

    Khan, M. A.; Okeefe, J. A.

    1973-01-01

    Specific reference figures are recommended for consistent use in geophysics and geodesy. The selection of appropriate reference figure for geophysical studies suggests a relationship between the Antarctic negative gravity anomaly and the great shrinkage of the Antarctic ice cap about 4-5 million years ago. The depression of the south polar regions relative to the north polar regions makes the Southern Hemisphere flatter than the Northern Hemisphere, thus producing the third harmonic (pear-shaped) contribution to the earth's figure.

  7. Metabolic, metallic, and mitotic sources of oxidative stress in Alzheimer disease.

    PubMed

    Smith, M A; Nunomura, A; Zhu, X; Takeda, A; Perry, G

    2000-01-01

    , iron regulatory proteins 1 and 2, ceruloplasmin, and dimethylargininase, our results indicate that iron misregulation could play an important role in the pathogenesis of AD and therefore chelation therapy may be a useful therapeutic approach. Finally, we wanted to determine the proximal cause of mitochondrial abnormalities. One interesting mechanisms involves re-entry into the cell cycle, at which point organellokinesis and proliferation results in increased mitochondria. Supporting this, we have considerable in vivo and in vitro evidence for mitotic disturbances in AD and its relationship with the pathogenesis of AD. PMID:11229355

  8. Caspase-3-mediated degradation of condensin Cap-H regulates mitotic cell death.

    PubMed

    Lai, S-K; Wong, C-H; Lee, Y-P; Li, H-Y

    2011-06-01

    Mitotic death is a major form of cell death in cancer cells that have been treated with chemotherapeutic drugs. However, the mechanisms underlying this form of cell death is poorly understood. Here, we report that the loss of chromosome integrity is an important determinant of mitotic death. During prolonged mitotic arrest, caspase-3 is activated and it cleaves Cap-H, a subunit of condensin I. The depletion of Cap-H results in the loss of condensin I complex at the chromosomes, thus affecting the integrity of the chromosomes. Consequently, DNA fragmentation by caspase-activated DNase is facilitated, thus driving the cell towards mitotic death. By expressing a caspase-resistant form of Cap-H, mitotic death is abrogated and the cells are able to reenter interphase after a long mitotic delay. Taken together, we provide new insights into the molecular events that occur during mitotic death.

  9. Cell cycle regulation of the activity and subcellular localization of Plk1, a human protein kinase implicated in mitotic spindle function

    PubMed Central

    1995-01-01

    Correct assembly and function of the mitotic spindle during cell division is essential for the accurate partitioning of the duplicated genome to daughter cells. Protein phosphorylation has long been implicated in controlling spindle function and chromosome segregation, and genetic studies have identified several protein kinases and phosphatases that are likely to regulate these processes. In particular, mutations in the serine/threonine-specific Drosophila kinase polo, and the structurally related kinase Cdc5p of Saccharomyces cerevisae, result in abnormal mitotic and meiotic divisions. Here, we describe a detailed analysis of the cell cycle-dependent activity and subcellular localization of Plk1, a recently identified human protein kinase with extensive sequence similarity to both Drosophila polo and S. cerevisiae Cdc5p. With the aid of recombinant baculoviruses, we have established a reliable in vitro assay for Plk1 kinase activity. We show that the activity of human Plk1 is cell cycle regulated, Plk1 activity being low during interphase but high during mitosis. We further show, by immunofluorescent confocal laser scanning microscopy, that human Plk1 binds to components of the mitotic spindle at all stages of mitosis, but undergoes a striking redistribution as cells progress from metaphase to anaphase. Specifically, Plk1 associates with spindle poles up to metaphase, but relocalizes to the equatorial plane, where spindle microtubules overlap (the midzone), as cells go through anaphase. These results indicate that the association of Plk1 with the spindle is highly dynamic and that Plk1 may function at multiple stages of mitotic progression. Taken together, our data strengthen the notion that human Plk1 may represent a functional homolog of polo and Cdc5p, and they suggest that this kinase plays an important role in the dynamic function of the mitotic spindle during chromosome segregation. PMID:7790358

  10. Deacetylation of the mitotic checkpoint protein BubR1 at lysine 250 by SIRT2 and subsequent effects on BubR1 degradation during the prometaphase/anaphase transition.

    PubMed

    Suematsu, Tomohisa; Li, Yanze; Kojima, Hirotada; Nakajima, Koichi; Oshimura, Mitsuo; Inoue, Toshiaki

    2014-10-24

    Mitotic catastrophe, a form of cell death that occurs during mitosis and after mitotic slippage to a tetraploid state, plays an important role in the efficacy of cancer cell killing by microtubule inhibitors. Prolonged mitotic arrest at the spindle assembly checkpoint (SAC) is a well-known requirement for mitotic catastrophe and, thus, for conferring sensitivity to microtubule inhibitors. We previously reported that downregulation of SIRT2, a member of the sirtuin family of NAD+-dependent deacetylases, confers resistance to microtubule inhibitors by abnormally prolonging mitotic arrest and thus compromising the cell death pathway after mitotic slippage. Thus, turning off SAC activation after a defined period is an additional requirement for efficient post-slippage death. Here, we investigated whether SIRT2 deacetylates BubR1, which is a core component of the SAC; acetylation of BubR1 at lysine 250 (K250) during prometaphase inhibits its APC/C-dependent proteolysis and thus regulates timing in anaphase entry. We showed that SIRT2 deacetylates BubR1 K250 both in vitro and in vivo. We also found that SIRT2 knockdown leads to increased levels of BubR1 acetylation at prometaphase; however, this increase is not substantial to elevate the levels of total BubR1 or delay the transition from prometaphase to anaphase. The present study shows that SIRT2 is a deacetylase for BubR1 K250, although the abnormally prolonged SAC activation observed in SIRT2 knockdown cells is not accompanied by a change in BubR1 levels or by delayed progression from prometaphase to anaphase.

  11. Abnormal uterine bleeding.

    PubMed

    Jennings, J C

    1995-11-01

    Physicians who care for female patients cannot avoid the frequent complaint of abnormal uterine bleeding. Knowledge of the disorders that cause this problem can prevent serious consequences in many patients and improve the quality of life for many others. The availability of noninvasive and minimally invasive diagnostic studies and minimally invasive surgical treatment has revolutionized management of abnormal uterine bleeding. Similar to any other disorder, the extent to which a physician manages abnormal uterine bleeding depends on his or her own level of comfort. When limitations of either diagnostic or therapeutic capability are encountered, consultation and referral should be used to the best interest of patients.

  12. Regulation of mitotic progression by the spindle assembly checkpoint

    PubMed Central

    Lischetti, Tiziana; Nilsson, Jakob

    2015-01-01

    Equal segregation of sister chromatids during mitosis requires that pairs of kinetochores establish proper attachment to microtubules emanating from opposite poles of the mitotic spindle. The spindle assembly checkpoint (SAC) protects against errors in segregation by delaying sister separation in response to improper kinetochore–microtubule interactions, and certain checkpoint proteins help to establish proper attachments. Anaphase entry is inhibited by the checkpoint through assembly of the mitotic checkpoint complex (MCC) composed of the 2 checkpoint proteins, Mad2 and BubR1, bound to Cdc20. The outer kinetochore acts as a catalyst for MCC production through the recruitment and proper positioning of checkpoint proteins and recently there has been remarkable progress in understanding how this is achieved. Here, we highlight recent advances in our understanding of kinetochore–checkpoint protein interactions and inhibition of the anaphase promoting complex by the MCC. PMID:27308407

  13. A comprehensive model to predict mitotic division in budding yeasts

    PubMed Central

    Sutradhar, Sabyasachi; Yadav, Vikas; Sridhar, Shreyas; Sreekumar, Lakshmi; Bhattacharyya, Dibyendu; Ghosh, Santanu Kumar; Paul, Raja; Sanyal, Kaustuv

    2015-01-01

    High-fidelity chromosome segregation during cell division depends on a series of concerted interdependent interactions. Using a systems biology approach, we built a robust minimal computational model to comprehend mitotic events in dividing budding yeasts of two major phyla: Ascomycota and Basidiomycota. This model accurately reproduces experimental observations related to spindle alignment, nuclear migration, and microtubule (MT) dynamics during cell division in these yeasts. The model converges to the conclusion that biased nucleation of cytoplasmic microtubules (cMTs) is essential for directional nuclear migration. Two distinct pathways, based on the population of cMTs and cortical dyneins, differentiate nuclear migration and spindle orientation in these two phyla. In addition, the model accurately predicts the contribution of specific classes of MTs in chromosome segregation. Thus we present a model that offers a wider applicability to simulate the effects of perturbation of an event on the concerted process of the mitotic cell division. PMID:26310442

  14. A comprehensive model to predict mitotic division in budding yeasts.

    PubMed

    Sutradhar, Sabyasachi; Yadav, Vikas; Sridhar, Shreyas; Sreekumar, Lakshmi; Bhattacharyya, Dibyendu; Ghosh, Santanu Kumar; Paul, Raja; Sanyal, Kaustuv

    2015-11-01

    High-fidelity chromosome segregation during cell division depends on a series of concerted interdependent interactions. Using a systems biology approach, we built a robust minimal computational model to comprehend mitotic events in dividing budding yeasts of two major phyla: Ascomycota and Basidiomycota. This model accurately reproduces experimental observations related to spindle alignment, nuclear migration, and microtubule (MT) dynamics during cell division in these yeasts. The model converges to the conclusion that biased nucleation of cytoplasmic microtubules (cMTs) is essential for directional nuclear migration. Two distinct pathways, based on the population of cMTs and cortical dyneins, differentiate nuclear migration and spindle orientation in these two phyla. In addition, the model accurately predicts the contribution of specific classes of MTs in chromosome segregation. Thus we present a model that offers a wider applicability to simulate the effects of perturbation of an event on the concerted process of the mitotic cell division.

  15. Brownian dynamics simulation of fission yeast mitotic spindle formation

    NASA Astrophysics Data System (ADS)

    Edelmaier, Christopher

    2014-03-01

    The mitotic spindle segregates chromosomes during mitosis. The dynamics that establish bipolar spindle formation are not well understood. We have developed a computational model of fission-yeast mitotic spindle formation using Brownian dynamics and kinetic Monte Carlo methods. Our model includes rigid, dynamic microtubules, a spherical nuclear envelope, spindle pole bodies anchored in the nuclear envelope, and crosslinkers and crosslinking motor proteins. Crosslinkers and crosslinking motor proteins attach and detach in a grand canonical ensemble, and exert forces and torques on the attached microtubules. We have modeled increased affinity for crosslinking motor attachment to antiparallel microtubule pairs, and stabilization of microtubules in the interpolar bundle. We study parameters controlling the stability of the interpolar bundle and assembly of a bipolar spindle from initially adjacent spindle-pole bodies.

  16. "Jeopardy" in Abnormal Psychology.

    ERIC Educational Resources Information Center

    Keutzer, Carolin S.

    1993-01-01

    Describes the use of the board game, Jeopardy, in a college level abnormal psychology course. Finds increased student interaction and improved application of information. Reports generally favorable student evaluation of the technique. (CFR)

  17. Abnormal Uterine Bleeding

    MedlinePlus

    ... Abnormal uterine bleeding is any bleeding from the uterus (through your vagina) other than your normal monthly ... or fibroids (small and large growths) in the uterus can also cause bleeding. Rarely, a thyroid problem, ...

  18. Abnormal Uterine Bleeding FAQ

    MedlinePlus

    ... as cancer of the uterus, cervix, or vagina • Polycystic ovary syndrome How is abnormal bleeding diagnosed? Your health care ... before the fetus can survive outside the uterus. Polycystic Ovary Syndrome: A condition characterized by two of the following ...

  19. Different cell fates after mitotic slippage: From aneuploidy to polyploidy.

    PubMed

    Ohashi, Akihiro

    2016-03-01

    The molecular mechanism responsible for cell fate after mitotic slippage remains unclear. We investigated the different postmitotic effects of aneuploidy versus polyploidy using chemical inhibitors of centromere-associated protein-E (CENP-E) and kinesin family member 11 (KIF11, also known as Eg5). Aneuploidy caused substantial proteotoxic stress and DNA damage accompanied by p53-mediated postmitotic apoptosis, whereas polyploidy did not induce these antiproliferative effects. PMID:27308610

  20. Cyto-3D-print to attach mitotic cells.

    PubMed

    Castroagudin, Michelle R; Zhai, Yujia; Li, Zhi; Marnell, Michael G; Glavy, Joseph S

    2016-08-01

    The Cyto-3D-print is an adapter that adds cytospin capability to a standard centrifuge. Like standard cytospinning, Cyto-3D-print increases the surface attachment of mitotic cells while giving a higher degree of adaptability to other slide chambers than available commercial devices. The use of Cyto-3D-print is cost effective, safe, and applicable to many slide designs. It is durable enough for repeated use and made of biodegradable materials for environment-friendly disposal.

  1. Observing Mitotic Division and Dynamics in a Live Zebrafish Embryo.

    PubMed

    Percival, Stefanie M; Parant, John M

    2016-01-01

    Mitosis is critical for organismal growth and differentiation. The process is highly dynamic and requires ordered events to accomplish proper chromatin condensation, microtubule-kinetochore attachment, chromosome segregation, and cytokinesis in a small time frame. Errors in the delicate process can result in human disease, including birth defects and cancer. Traditional approaches investigating human mitotic disease states often rely on cell culture systems, which lack the natural physiology and developmental/tissue-specific context advantageous when studying human disease. This protocol overcomes many obstacles by providing a way to visualize, with high resolution, chromosome dynamics in a vertebrate system, the zebrafish. This protocol will detail an approach that can be used to obtain dynamic images of dividing cells, which include: in vitro transcription, zebrafish breeding/collecting, embryo embedding, and time-lapse imaging. Optimization and modifications of this protocol are also explored. Using H2A.F/Z-EGFP (labels chromatin) and mCherry-CAAX (labels cell membrane) mRNA-injected embryos, mitosis in AB wild-type, auroraB(hi1045) (,) and esco2(hi2865) mutant zebrafish is visualized. High resolution live imaging in zebrafish allows one to observe multiple mitoses to statistically quantify mitotic defects and timing of mitotic progression. In addition, observation of qualitative aspects that define improper mitotic processes (i.e., congression defects, missegregation of chromosomes, etc.) and improper chromosomal outcomes (i.e., aneuploidy, polyploidy, micronuclei, etc.) are observed. This assay can be applied to the observation of tissue differentiation/development and is amenable to the use of mutant zebrafish and pharmacological agents. Visualization of how defects in mitosis lead to cancer and developmental disorders will greatly enhance understanding of the pathogenesis of disease. PMID:27501381

  2. Mitotic activity in dorsal epidermis of Rana pipiens.

    NASA Technical Reports Server (NTRS)

    Garcia-Arce, H.; Mizell, S.

    1972-01-01

    Study of statistically significant rhythms of mitotic division in dorsal epidermis of frogs, Rana pipiens, exposed to a 12:12 light:dark environment for 14 days. The results include the findings that (1) male animals have a primary period of 22 hr in summer and 18 hr in winter, (2) female animals have an 18 hr period, and (3) parapinealectomy and blinding abolish the rhythm.

  3. Mitotic exit: Determining the PP2A dephosphorylation program.

    PubMed

    Pereira, Gislene; Schiebel, Elmar

    2016-08-29

    In mitotic exit, proteins that were highly phosphorylated are sequentially targeted by the phosphatase PP2A-B55, but what underlies substrate selection is unclear. In this issue, Cundell et al. (2016. J. Cell Biol http://dx.doi.org/10.1083/jcb.201606033) identify the determinants of PP2A-B55's dephosphorylation program, thereby influencing spindle disassembly, nuclear envelope reformation, and cytokinesis.

  4. 46 CFR 69.123 - Figures.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 2 2013-10-01 2013-10-01 false Figures. 69.123 Section 69.123 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) DOCUMENTATION AND MEASUREMENT OF VESSELS MEASUREMENT OF VESSELS Standard Measurement System § 69.123 Figures. EC01FE91.042 EC01FE91.043 EC01FE91.044...

  5. Evolution of the Significant Figure Rules

    ERIC Educational Resources Information Center

    Carter, Ashley R.

    2013-01-01

    Today, almost all introductory physics textbooks include standardized "rules" on how to find the number of significant figures in a calculated value. And yet, 30 years ago these rules were almost nonexistent. Why have we increased the role of significant figures in introductory classes, and should we continue this trend? A look back at…

  6. "Blessed": Musical Talent, Smartness, & Figured Identities

    ERIC Educational Resources Information Center

    Hoffman, Adria R.

    2015-01-01

    The purpose of this study is to explore smartness and talent as social constructs. Drawing on Holland et al.'s (1998) figured identities, this article explores the figuring of abilities by elucidating the voices of African American high school chorus students. Critical Race Theory (CRT) helps to unpack normalized language and practices that…

  7. Teaching Significant Figures Using a Learning Cycle.

    ERIC Educational Resources Information Center

    Guymon, E. Park; And Others

    1986-01-01

    Describes an instructional strategy based on the learning cycle for teaching the use of significant figures. Provides explanations of teaching activities for each phase of the learning cycle (exploration, invention, application). Compares this approach to teaching significant figures with the traditional textbook approach. (TW)

  8. Aero-space plane figures of merit

    NASA Technical Reports Server (NTRS)

    Hunt, James L.; Martin, John G.

    1992-01-01

    The design environment of the aerospace plane is variable rich, intricately networked and sensitivity intensive. To achieve a viable design necessitates addressing three principal elements: knowledge of the 'figures of merit' and their relationships, the synthesis procedure, and the synergistic integration of advanced technologies across the discipline spectrum. This paper focuses on the 'figures of merit' that create the design of an aerospace plane.

  9. The Development of Ambiguous Figure Perception

    ERIC Educational Resources Information Center

    Wimmer, Marina C.; Doherty, Martin J.

    2011-01-01

    Ambiguous figures have fascinated researchers for almost 200 years. The physical properties of these figures remain constant, yet two distinct interpretations are possible; these reverse (switch) from one percept to the other. The consensus is that reversal requires complex interaction of perceptual bottom-up and cognitive top-down elements. The…

  10. Figure-Associated Text Summarization and Evaluation

    PubMed Central

    Polepalli Ramesh, Balaji; Sethi, Ricky J.; Yu, Hong

    2015-01-01

    Biomedical literature incorporates millions of figures, which are a rich and important knowledge resource for biomedical researchers. Scientists need access to the figures and the knowledge they represent in order to validate research findings and to generate new hypotheses. By themselves, these figures are nearly always incomprehensible to both humans and machines and their associated texts are therefore essential for full comprehension. The associated text of a figure, however, is scattered throughout its full-text article and contains redundant information content. In this paper, we report the continued development and evaluation of several figure summarization systems, the FigSum+ systems, that automatically identify associated texts, remove redundant information, and generate a text summary for every figure in an article. Using a set of 94 annotated figures selected from 19 different journals, we conducted an intrinsic evaluation of FigSum+. We evaluate the performance by precision, recall, F1, and ROUGE scores. The best FigSum+ system is based on an unsupervised method, achieving F1 score of 0.66 and ROUGE-1 score of 0.97. The annotated data is available at figshare.com (http://figshare.com/articles/Figure_Associated_Text_Summarization_and_Evaluation/858903). PMID:25643357

  11. Feature Assignment in Perception of Auditory Figure

    ERIC Educational Resources Information Center

    Gregg, Melissa K.; Samuel, Arthur G.

    2012-01-01

    Because the environment often includes multiple sounds that overlap in time, listeners must segregate a sound of interest (the auditory figure) from other co-occurring sounds (the unattended auditory ground). We conducted a series of experiments to clarify the principles governing the extraction of auditory figures. We distinguish between auditory…

  12. Plasma surface figuring of large optical components

    NASA Astrophysics Data System (ADS)

    Jourdain, R.; Castelli, M.; Morantz, P.; Shore, P.

    2012-04-01

    Fast figuring of large optical components is well known as a highly challenging manufacturing issue. Different manufacturing technologies including: magnetorheological finishing, loose abrasive polishing, ion beam figuring are presently employed. Yet, these technologies are slow and lead to expensive optics. This explains why plasma-based processes operating at atmospheric pressure have been researched as a cost effective means for figure correction of metre scale optical surfaces. In this paper, fast figure correction of a large optical surface is reported using the Reactive Atom Plasma (RAP) process. Achievements are shown following the scaling-up of the RAP figuring process to a 400 mm diameter area of a substrate made of Corning ULE®. The pre-processing spherical surface is characterized by a 3 metres radius of curvature, 2.3 μm PVr (373nm RMS), and 1.2 nm Sq nanometre roughness. The nanometre scale correction figuring system used for this research work is named the HELIOS 1200, and it is equipped with a unique plasma torch which is driven by a dedicated tool path algorithm. Topography map measurements were carried out using a vertical work station instrumented by a Zygo DynaFiz interferometer. Figuring results, together with the processing times, convergence levels and number of iterations, are reported. The results illustrate the significant potential and advantage of plasma processing for figuring correction of large silicon based optical components.

  13. Ambiguous figures: living versus nonliving objects.

    PubMed

    Verstijnen, Ilse M; Wagemans, Johan

    2004-01-01

    Eleven series of figures were studied, each series ranging from one extreme interpretation via five ambiguous intermediates to a second extreme interpretation. Triplets consisting of an ambiguous exemplar in the middle flanked on the left and right by its two extreme interpretations were presented to large groups of subjects. The initial aim was to establish the levels of perceptual ambiguity of each exemplar in a series, and normative data on the ambiguous figures are provided for future reference and use. However, several biases were encountered and these were examined in more detail. In experiment 1 the subject's task was to compare the middle figure with the flankers and draw an arrow from the middle figure towards the flanking extreme they judged the most similar. Here, an overall preference for the left extreme was found. Therefore the instructions were reversed in experiment 2; flankers had to be compared with the middle figure. The preference for the left extreme remained for figures of living objects, but for nonliving objects the preference switched to the right extreme. To do away with any effect of the arrows, in experiment 3 subjects were divided into two groups each receiving different instructions and were asked to circle one of the extremes. However, the pattern of biases remained the same. The bias found with figures of living objects may be explained on the basis of top-down processes. For nonliving figures, an hypothesis based on bottom-up processes like neural fatigue was considered but rejected. PMID:15250659

  14. Trichomonas vaginalis: chromatin and mitotic spindle during mitosis.

    PubMed

    Gómez-Conde, E; Mena-López, R; Hernández-Jaúregui, P; González-Camacho, M; Arroyo, R

    2000-11-01

    The mitotic phases and the changes that the chromatin and mitotic microtubules undergo during mitosis in the sexually transmitted parasite Trichomonas vaginalis are described. Parasites arrested in the gap 2 phase of the cell cycle by nutrient starvation were induced to mitosis by addition of fresh whole medium. [(3)H] Thymidine labeling of trichomonad parasites for 24 h showed that parasites have at least four synchronic duplications after mitosis induction. Fixed or live and acridine orange (AO)-stained trichomonads analyzed at different times during mitosis by epifluorescence microscopy showed that mitosis took about 45 min and is divided into five stages: prophase, metaphase, early and late anaphase, early and late telophase, and cytokinesis. The AO-stained nucleus of live trichomonads showed green (DNA) and orange (RNA) fluorescence, and the nucleic acid nature was confirmed by DNase and RNase treatment, respectively. The chromatin appeared partially condensed during interphase. At metaphase, it appeared as six condensed chromosomes, as recently reported, which decondensed at anaphase and migrated to the nuclear poles at telophase. In addition, small bundles of microtubules (as hemispindles) were detected only in metaphase with the polyclonal antibody anti-Entamoeba histolytica alpha-tubulin. This antibody showed that the hemispindle and an atractophore-like structure seem to duplicate and polarize during metaphase. In conclusion, T. vaginalis mitosis involves five mitotic phases in which the chromatin undergoes different degrees of condensation, from chromosomes to decondensed chromatin, and two hemispindles that are observed only in the metaphase stage. PMID:11162363

  15. A membrane-specific tyrosinase chelate: the mitotic regulator?

    PubMed

    Kharasch, J A

    1987-06-01

    Cancer's random, reversible, unstable transitions to "normal" structures imply their functional relation. Similar random, continuous, reversible oncogene "mutational transformation" also lacks a consistent hybrid. Positing cancer's "mutationally altered genotype" leads to medically foreign causes, qualities, inducers, suppressors, immune proteins, and viruses. Its random variation, however, opposes the functionally discrete, ordered, stable, irreversible hybrid variation and single-valued transforms of molecular genetics. There, "causal mutational operators" remain unspecified; only consistent single-valued DNA base and amino acid change, as "transform operand", are made explicit. A mitotically "blocked" (normal) and "unblocked" (malignant) stem cell "phenotype", operationally constructed from microscopic data, is therefore viewed within the homeostatic context of open-system enzyme-regulatory equilibrium. This functional, stochastic field distribution between "structurally bound" and "freely dividing" stem cell number discloses their putative regulatory mitotic-blocking factor. A tyrosinase complex, interacting by Cu2+-Fe2+ chelation with a proline hydroxylase divisional enzyme near stem cell ribosomes, maintains steady-state mitotic equilibrium. Based upon familiar medical, biochemical, and energy principles this confronts cancer's pigmentary-depigmentary signs, glycolytic metabolism, elevated serum tyrosinase, defective collagen production, exposed membrane binding sites, and tyrosine's recent growth control role. PMID:3112530

  16. Mitotic Exit in the Absence of Separase Activity

    PubMed Central

    Lu, Ying

    2009-01-01

    In budding yeast, three interdigitated pathways regulate mitotic exit (ME): mitotic cyclin–cyclin-dependent kinase (Cdk) inactivation; the Cdc14 early anaphase release (FEAR) network, including a nonproteolytic function of separase (Esp1); and the mitotic exit network (MEN) driven by interaction between the spindle pole body and the bud cortex. Here, we evaluate the contributions of these pathways to ME kinetics. Reducing Cdk activity is critical for ME, and the MEN contributes strongly to ME efficiency. Esp1 contributes to ME kinetics mainly through cohesin cleavage: the Esp1 requirement can be largely bypassed if cells are provided Esp1-independent means of separating sister chromatids. In the absence of Esp1 activity, we observed only a minor ME delay consistent with a FEAR defect. Esp1 overexpression drives ME in Cdc20-depleted cells arrested in metaphase. We have found that this activity of overexpressed Esp1 depended on spindle integrity and the MEN. We defined the first quantitative measure for Cdc14 release based on colocalization with the Net1 nucleolar anchor. This measure indicates efficient Cdc14 release upon MEN activation; release driven by Esp1 in the absence of microtubules was inefficient and incapable of driving ME. We also found a novel role for the MEN: activating Cdc14 nuclear export, even in the absence of Net1. PMID:19144818

  17. SUMOylation inhibits FOXM1 activity and delays mitotic transition.

    PubMed

    Myatt, S S; Kongsema, M; Man, C W-Y; Kelly, D J; Gomes, A R; Khongkow, P; Karunarathna, U; Zona, S; Langer, J K; Dunsby, C W; Coombes, R C; French, P M; Brosens, J J; Lam, E W-F

    2014-08-21

    The forkhead box transcription factor FOXM1 is an essential effector of G2/M-phase transition, mitosis and the DNA damage response. As such, it is frequently deregulated during tumorigenesis. Here we report that FOXM1 is dynamically modified by SUMO1 but not by SUMO2/3 at multiple sites. We show that FOXM1 SUMOylation is enhanced in MCF-7 breast cancer cells in response to treatment with epirubicin and mitotic inhibitors. Mutation of five consensus conjugation motifs yielded a SUMOylation-deficient mutant FOXM1. Conversely, fusion of the E2 ligase Ubc9 to FOXM1 generated an auto-SUMOylating mutant (FOXM1-Ubc9). Analysis of wild-type FOXM1 and mutants revealed that SUMOylation inhibits FOXM1 activity, promotes translocation to the cytoplasm and enhances APC/Cdh1-mediated ubiquitination and degradation. Further, expression of the SUMOylation-deficient mutant enhanced cell proliferation compared with wild-type FOXM1, whereas the FOXM1-Ubc9 fusion protein resulted in persistent cyclin B1 expression and slowed the time from mitotic entry to exit. In summary, our findings suggest that SUMOylation attenuates FOXM1 activity and causes mitotic delay in cytotoxic drug response.

  18. Daxx regulates mitotic progression and prostate cancer predisposition.

    PubMed

    Kwan, Pak Shing; Lau, Chi Chiu; Chiu, Yung Tuen; Man, Cornelia; Liu, Ji; Tang, Kai Dun; Wong, Yong Chuan; Ling, Ming-Tat

    2013-04-01

    Mitotic progression of mammalian cells is tightly regulated by the E3 ubiquitin ligase anaphase promoting complex (APC)/C. Deregulation of APC/C is frequently observed in cancer cells and is suggested to contribute to chromosome instability and cancer predisposition. In this study, we identified Daxx as a novel APC/C inhibitor frequently overexpressed in prostate cancer. Daxx interacts with the APC/C coactivators Cdc20 and Cdh1 in vivo, with the binding of Cdc20 dependent on the consensus destruction boxes near the N-terminal of the Daxx protein. Ectopic expression of Daxx, but not the D-box deleted mutant (DaxxΔD-box), inhibited the degradation of APC/Cdc20 and APC/Cdh1 substrates, leading to a transient delay in mitotic progression. Daxx is frequently upregulated in prostate cancer tissues; the expression level positively correlated with the Gleason score and disease metastasis (P = 0.027 and 0.032, respectively). Furthermore, ectopic expression of Daxx in a non-malignant prostate epithelial cell line induced polyploidy under mitotic stress. Our data suggest that Daxx may function as a novel APC/C inhibitor, which promotes chromosome instability during prostate cancer development.

  19. Trichomonas vaginalis: chromatin and mitotic spindle during mitosis.

    PubMed

    Gómez-Conde, E; Mena-López, R; Hernández-Jaúregui, P; González-Camacho, M; Arroyo, R

    2000-11-01

    The mitotic phases and the changes that the chromatin and mitotic microtubules undergo during mitosis in the sexually transmitted parasite Trichomonas vaginalis are described. Parasites arrested in the gap 2 phase of the cell cycle by nutrient starvation were induced to mitosis by addition of fresh whole medium. [(3)H] Thymidine labeling of trichomonad parasites for 24 h showed that parasites have at least four synchronic duplications after mitosis induction. Fixed or live and acridine orange (AO)-stained trichomonads analyzed at different times during mitosis by epifluorescence microscopy showed that mitosis took about 45 min and is divided into five stages: prophase, metaphase, early and late anaphase, early and late telophase, and cytokinesis. The AO-stained nucleus of live trichomonads showed green (DNA) and orange (RNA) fluorescence, and the nucleic acid nature was confirmed by DNase and RNase treatment, respectively. The chromatin appeared partially condensed during interphase. At metaphase, it appeared as six condensed chromosomes, as recently reported, which decondensed at anaphase and migrated to the nuclear poles at telophase. In addition, small bundles of microtubules (as hemispindles) were detected only in metaphase with the polyclonal antibody anti-Entamoeba histolytica alpha-tubulin. This antibody showed that the hemispindle and an atractophore-like structure seem to duplicate and polarize during metaphase. In conclusion, T. vaginalis mitosis involves five mitotic phases in which the chromatin undergoes different degrees of condensation, from chromosomes to decondensed chromatin, and two hemispindles that are observed only in the metaphase stage.

  20. A membrane-specific tyrosinase chelate: the mitotic regulator?

    PubMed

    Kharasch, J A

    1987-06-01

    Cancer's random, reversible, unstable transitions to "normal" structures imply their functional relation. Similar random, continuous, reversible oncogene "mutational transformation" also lacks a consistent hybrid. Positing cancer's "mutationally altered genotype" leads to medically foreign causes, qualities, inducers, suppressors, immune proteins, and viruses. Its random variation, however, opposes the functionally discrete, ordered, stable, irreversible hybrid variation and single-valued transforms of molecular genetics. There, "causal mutational operators" remain unspecified; only consistent single-valued DNA base and amino acid change, as "transform operand", are made explicit. A mitotically "blocked" (normal) and "unblocked" (malignant) stem cell "phenotype", operationally constructed from microscopic data, is therefore viewed within the homeostatic context of open-system enzyme-regulatory equilibrium. This functional, stochastic field distribution between "structurally bound" and "freely dividing" stem cell number discloses their putative regulatory mitotic-blocking factor. A tyrosinase complex, interacting by Cu2+-Fe2+ chelation with a proline hydroxylase divisional enzyme near stem cell ribosomes, maintains steady-state mitotic equilibrium. Based upon familiar medical, biochemical, and energy principles this confronts cancer's pigmentary-depigmentary signs, glycolytic metabolism, elevated serum tyrosinase, defective collagen production, exposed membrane binding sites, and tyrosine's recent growth control role.

  1. On the molecular mechanisms of mitotic kinase activation.

    PubMed

    Bayliss, Richard; Fry, Andrew; Haq, Tamanna; Yeoh, Sharon

    2012-11-01

    During mitosis, human cells exhibit a peak of protein phosphorylation that alters the behaviour of a significant proportion of proteins, driving a dramatic transformation in the cell's shape, intracellular structures and biochemistry. These mitotic phosphorylation events are catalysed by several families of protein kinases, including Auroras, Cdks, Plks, Neks, Bubs, Haspin and Mps1/TTK. The catalytic activities of these kinases are activated by phosphorylation and through protein-protein interactions. In this review, we summarize the current state of knowledge of the structural basis of mitotic kinase activation mechanisms. This review aims to provide a clear and comprehensive primer on these mechanisms to a broad community of researchers, bringing together the common themes, and highlighting specific differences. Along the way, we have uncovered some features of these proteins that have previously gone unreported, and identified unexplored questions for future work. The dysregulation of mitotic kinases is associated with proliferative disorders such as cancer, and structural biology will continue to play a critical role in the development of chemical probes used to interrogate disease biology and applied to the treatment of patients. PMID:23226601

  2. On the molecular mechanisms of mitotic kinase activation.

    PubMed

    Bayliss, Richard; Fry, Andrew; Haq, Tamanna; Yeoh, Sharon

    2012-11-01

    During mitosis, human cells exhibit a peak of protein phosphorylation that alters the behaviour of a significant proportion of proteins, driving a dramatic transformation in the cell's shape, intracellular structures and biochemistry. These mitotic phosphorylation events are catalysed by several families of protein kinases, including Auroras, Cdks, Plks, Neks, Bubs, Haspin and Mps1/TTK. The catalytic activities of these kinases are activated by phosphorylation and through protein-protein interactions. In this review, we summarize the current state of knowledge of the structural basis of mitotic kinase activation mechanisms. This review aims to provide a clear and comprehensive primer on these mechanisms to a broad community of researchers, bringing together the common themes, and highlighting specific differences. Along the way, we have uncovered some features of these proteins that have previously gone unreported, and identified unexplored questions for future work. The dysregulation of mitotic kinases is associated with proliferative disorders such as cancer, and structural biology will continue to play a critical role in the development of chemical probes used to interrogate disease biology and applied to the treatment of patients.

  3. On the molecular mechanisms of mitotic kinase activation

    PubMed Central

    Bayliss, Richard; Fry, Andrew; Haq, Tamanna; Yeoh, Sharon

    2012-01-01

    During mitosis, human cells exhibit a peak of protein phosphorylation that alters the behaviour of a significant proportion of proteins, driving a dramatic transformation in the cell's shape, intracellular structures and biochemistry. These mitotic phosphorylation events are catalysed by several families of protein kinases, including Auroras, Cdks, Plks, Neks, Bubs, Haspin and Mps1/TTK. The catalytic activities of these kinases are activated by phosphorylation and through protein–protein interactions. In this review, we summarize the current state of knowledge of the structural basis of mitotic kinase activation mechanisms. This review aims to provide a clear and comprehensive primer on these mechanisms to a broad community of researchers, bringing together the common themes, and highlighting specific differences. Along the way, we have uncovered some features of these proteins that have previously gone unreported, and identified unexplored questions for future work. The dysregulation of mitotic kinases is associated with proliferative disorders such as cancer, and structural biology will continue to play a critical role in the development of chemical probes used to interrogate disease biology and applied to the treatment of patients. PMID:23226601

  4. Toward automatic mitotic cell detection and segmentation in multispectral histopathological images.

    PubMed

    Lu, Cheng; Mandal, Mrinal

    2014-03-01

    The count of mitotic cells is a critical factor in most cancer grading systems. Extracting the mitotic cell from the histopathological image is a very challenging task. In this paper, we propose an efficient technique for detecting and segmenting the mitotic cells in the high-resolution multispectral image. The proposed technique consists of three main modules: discriminative image generation, mitotic cell candidate detection and segmentation, and mitotic cell candidate classification. In the first module, a discriminative image is obtained by linear discriminant analysis using ten different spectral band images. A set of mitotic cell candidate regions is then detected and segmented by the Bayesian modeling and local-region threshold method. In the third module, a 226 dimension feature is extracted from the mitotic cell candidates and their surrounding regions. An imbalanced classification framework is then applied to perform the classification for the mitotic cell candidates in order to detect the real mitotic cells. The proposed technique has been evaluated on a publicly available dataset of 35 × 10 multispectral images, in which 224 mitotic cells are manually labeled by experts. The proposed technique is able to provide superior performance compared to the existing technique, 81.5% sensitivity rate and 33.9% precision rate in terms of detection performance, and 89.3% sensitivity rate and 87.5% precision rate in terms of segmentation performance.

  5. Human Nek7-interactor RGS2 is required for mitotic spindle organization

    PubMed Central

    de Souza, Edmarcia Elisa; Hehnly, Heidi; Perez, Arina Marina; Meirelles, Gabriela Vaz; Smetana, Juliana Helena Costa; Doxsey, Stephen; Kobarg, Jörg

    2015-01-01

    The mitotic spindle apparatus is composed of microtubule (MT) networks attached to kinetochores organized from 2 centrosomes (a.k.a. spindle poles). In addition to this central spindle apparatus, astral MTs assemble at the mitotic spindle pole and attach to the cell cortex to ensure appropriate spindle orientation. We propose that cell cycle-related kinase, Nek7, and its novel interacting protein RGS2, are involved in mitosis regulation and spindle formation. We found that RGS2 localizes to the mitotic spindle in a Nek7-dependent manner, and along with Nek7 contributes to spindle morphology and mitotic spindle pole integrity. RGS2-depletion leads to a mitotic-delay and severe defects in the chromosomes alignment and congression. Importantly, RGS2 or Nek7 depletion or even overexpression of wild-type or kinase-dead Nek7, reduced γ-tubulin from the mitotic spindle poles. In addition to causing a mitotic delay, RGS2 depletion induced mitotic spindle misorientation coinciding with astral MT-reduction. We propose that these phenotypes directly contribute to a failure in mitotic spindle alignment to the substratum. In conclusion, we suggest a molecular mechanism whereupon Nek7 and RGS2 may act cooperatively to ensure proper mitotic spindle organization. PMID:25664600

  6. Human Nek7-interactor RGS2 is required for mitotic spindle organization.

    PubMed

    de Souza, Edmarcia Elisa; Hehnly, Heidi; Perez, Arina Marina; Meirelles, Gabriela Vaz; Smetana, Juliana Helena Costa; Doxsey, Stephen; Kobarg, Jörg

    2015-01-01

    The mitotic spindle apparatus is composed of microtubule (MT) networks attached to kinetochores organized from 2 centrosomes (a.k.a. spindle poles). In addition to this central spindle apparatus, astral MTs assemble at the mitotic spindle pole and attach to the cell cortex to ensure appropriate spindle orientation. We propose that cell cycle-related kinase, Nek7, and its novel interacting protein RGS2, are involved in mitosis regulation and spindle formation. We found that RGS2 localizes to the mitotic spindle in a Nek7-dependent manner, and along with Nek7 contributes to spindle morphology and mitotic spindle pole integrity. RGS2-depletion leads to a mitotic-delay and severe defects in the chromosomes alignment and congression. Importantly, RGS2 or Nek7 depletion or even overexpression of wild-type or kinase-dead Nek7, reduced γ-tubulin from the mitotic spindle poles. In addition to causing a mitotic delay, RGS2 depletion induced mitotic spindle misorientation coinciding with astral MT-reduction. We propose that these phenotypes directly contribute to a failure in mitotic spindle alignment to the substratum. In conclusion, we suggest a molecular mechanism whereupon Nek7 and RGS2 may act cooperatively to ensure proper mitotic spindle organization.

  7. Bone morphogenetic protein (BMP) signaling regulates mitotic checkpoint protein levels in human breast cancer cells.

    PubMed

    Yan, Hualong; Zhu, Songcheng; Song, Chenlin; Liu, Naifa; Kang, Jiuhong

    2012-04-01

    Aberrant expression of mitotic checkpoint genes compromises mitotic checkpoint, leads to chromosome instability and tumorigenesis. However, the cell signals that control mitotic checkpoint gene expression have not been reported so far. In the present study we show that, in human breast cancer cells, chemical inhibition of Bone morphogenetic proteins (BMPs), but not Transforming Growth Factor-β (TGF-β), abrogates the mitotic arrest induced by nocodazole. Protein expression analysis reveals that inhibition of BMP signaling dramatically down regulates protein levels of mitotic checkpoint components BUB3, Hec1, TTK and MAD2, but inhibition of TGF-β has relatively minor effect on the expression of these proteins. Activation of BMP signaling specifically up regulates BUB3, and activation of Activin A signaling globally down regulates these proteins level. Furthermore, overexpressing MAD2, TTK, BUB3 or Hec1 significantly rescues the mitotic arrest defect caused by BMP inhibition. Our results demonstrated for the first time that TGF-β family cytokines are cellular signals regulating mitotic checkpoint and perturbations in intrinsic BMP signaling could lead to suppression of mitotic checkpoint signaling by downregulating key checkpoint proteins. The results suggest a possible mechanism by which dysregulation of TGF-β signaling causes mitotic checkpoint defects and drives tumorigenesis. The finding also provides a potential and more specific strategy for cancer prevention by targeting BMP and mitotic checkpoint connection. PMID:22234345

  8. Human Nek7-interactor RGS2 is required for mitotic spindle organization.

    PubMed

    de Souza, Edmarcia Elisa; Hehnly, Heidi; Perez, Arina Marina; Meirelles, Gabriela Vaz; Smetana, Juliana Helena Costa; Doxsey, Stephen; Kobarg, Jörg

    2015-01-01

    The mitotic spindle apparatus is composed of microtubule (MT) networks attached to kinetochores organized from 2 centrosomes (a.k.a. spindle poles). In addition to this central spindle apparatus, astral MTs assemble at the mitotic spindle pole and attach to the cell cortex to ensure appropriate spindle orientation. We propose that cell cycle-related kinase, Nek7, and its novel interacting protein RGS2, are involved in mitosis regulation and spindle formation. We found that RGS2 localizes to the mitotic spindle in a Nek7-dependent manner, and along with Nek7 contributes to spindle morphology and mitotic spindle pole integrity. RGS2-depletion leads to a mitotic-delay and severe defects in the chromosomes alignment and congression. Importantly, RGS2 or Nek7 depletion or even overexpression of wild-type or kinase-dead Nek7, reduced γ-tubulin from the mitotic spindle poles. In addition to causing a mitotic delay, RGS2 depletion induced mitotic spindle misorientation coinciding with astral MT-reduction. We propose that these phenotypes directly contribute to a failure in mitotic spindle alignment to the substratum. In conclusion, we suggest a molecular mechanism whereupon Nek7 and RGS2 may act cooperatively to ensure proper mitotic spindle organization. PMID:25664600

  9. 16 CFR Figure 3 to Part 1508 - Figure 3 to Part 1508

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 2 2014-01-01 2014-01-01 false Figure 3 to Part 1508 3 Figure 3 to Part 1508 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS FIREWORKS DEVICES Multiple-tube fireworks devices. Pt. 1508, Fig. 3 Figure 3 to Part 1508...

  10. 16 CFR Figure 3 to Part 1509 - Figure 3 to Part 1509

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Figure 3 to Part 1509 3 Figure 3 to Part 1509 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS REQUIREMENTS FOR NON-FULL-SIZE BABY CRIBS Pt. 1509, Fig. 3 Figure 3 to Part 1509 EC03OC91.066...

  11. 16 CFR Figure 1 to Part 1509 - Figure 1 to Part 1509

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Figure 1 to Part 1509 1 Figure 1 to Part 1509 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS REQUIREMENTS FOR NON-FULL-SIZE BABY CRIBS Pt. 1509, Fig. 1 Figure 1 to Part 1509 EC03OC91.064...

  12. 16 CFR Figure 1 to Part 1509 - Figure 1 to Part 1509

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 2 2011-01-01 2011-01-01 false Figure 1 to Part 1509 1 Figure 1 to Part 1509 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS REQUIREMENTS FOR NON-FULL-SIZE BABY CRIBS Pt. 1509, Fig. 1 Figure 1 to Part 1509 EC03OC91.064...

  13. 16 CFR Figure 3 to Part 1508 - Figure 3 to Part 1508

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Figure 3 to Part 1508 3 Figure 3 to Part 1508 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS REQUIREMENTS FOR FULL-SIZE BABY CRIBS Pt. 1508, Fig. 3 Figure 3 to Part 1508 EC03OC91.063...

  14. 16 CFR Figure 3 to Part 1508 - Figure 3 to Part 1508

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 2 2011-01-01 2011-01-01 false Figure 3 to Part 1508 3 Figure 3 to Part 1508 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS REQUIREMENTS FOR FULL-SIZE BABY CRIBS Pt. 1508, Fig. 3 Figure 3 to Part 1508 EC03OC91.063...

  15. 16 CFR Figure 3 to Part 1509 - Figure 3 to Part 1509

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 2 2011-01-01 2011-01-01 false Figure 3 to Part 1509 3 Figure 3 to Part 1509 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS REQUIREMENTS FOR NON-FULL-SIZE BABY CRIBS Pt. 1509, Fig. 3 Figure 3 to Part 1509 EC03OC91.066...

  16. 16 CFR Figure 3 to Part 1508 - Figure 3 to Part 1508

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 16 Commercial Practices 2 2013-01-01 2013-01-01 false Figure 3 to Part 1508 3 Figure 3 to Part 1508 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS FIREWORKS DEVICES Multiple-tube fireworks devices. Pt. 1508, Fig. 3 Figure 3 to Part 1508...

  17. 16 CFR Figure 3 to Part 1508 - Figure 3 to Part 1508

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 16 Commercial Practices 2 2012-01-01 2012-01-01 false Figure 3 to Part 1508 3 Figure 3 to Part 1508 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS FIREWORKS DEVICES Multiple-tube fireworks devices. Pt. 1508, Fig. 3 Figure 3 to Part 1508...

  18. Advanced figure sensor operations and maintenance manual

    NASA Technical Reports Server (NTRS)

    Robertson, H. J.

    1972-01-01

    This manual contains procedures for installing, operating, and maintaining the optical figure sensor and its associated electronic controls. The optical figure sensor, a system of integrated components, comprises: (1) a phase measuring modified interferometer employing a single frequency 6328 A laser, and a Vidissector; (2) a two-axis automatic thermal compensation control mount; (3) a five degree of freedom manual adjustment stand; and (4) a control console. This instrument provides real time output data of optical figure errors for spherical mirrors, and is also capable of measuring aspherical mirrors if a null corrector is added.

  19. The GTPase Gem and its partner Kif9 are required for chromosome alignment, spindle length control, and mitotic progression.

    PubMed

    Andrieu, Guillaume; Quaranta, Muriel; Leprince, Corinne; Hatzoglou, Anastassia

    2012-12-01

    Within the Ras superfamily, Gem is a small GTP-binding protein that plays a role in regulating Ca(2+) channels and cytoskeletal remodeling in interphase cells. Here, we report for the first time that Gem is a spindle-associated protein and is required for proper mitotic progression. Functionally, loss of Gem leads to misaligned chromosomes and prometaphase delay. On the basis of different experimental approaches, we demonstrate that loss of Gem by RNA interference induces spindle elongation, while its enforced expression results in spindle shortening. The spindle length phenotype is generated through deregulation of spindle dynamics on Gem depletion and requires the expression of its downstream effector, the kinesin Kif9. Loss of Kif9 induces spindle abnormalities similar to those observed when Gem expression is repressed by siRNA. We further identify Kif9 as a new regulator of spindle dynamics. Kif9 depletion increases the steady-state levels of spindle α-tubulin by increasing the rate of microtubule polymerization. Overall, this study demonstrates a novel mechanism by which Gem contributes to the mitotic progression by maintaining correct spindle length through the kinesin Kif9.

  20. Determination of genotoxic effects of Imazethapyr herbicide in Allium cepa root cells by mitotic activity, chromosome aberration, and comet assay.

    PubMed

    Liman, Recep; Ciğerci, İbrahim Hakkı; Öztürk, Nur Serap

    2015-02-01

    Imazethapyr (IM) is an imidazolinone herbicide that is currently used for broad-spectrum weed control in soybean and other legume crops. In this study, cytotoxic and genotoxic effects of IM were investigated by using mitotic index (MI), mitotic phases, chromosomal abnormalities (CAs) and DNA damage on the root meristem cells of Allium cepa. In Allium root growth inhibition test, EC50 value was determined as 20 ppm, and 0.5xEC50, EC50 and 2xEC50 concentrations of IM herbicide were introduced to onion tuber roots. Distilled water and methyl methane sulfonate (MMS, 10 mg/L) were used as a negative and positive control, respectively. As A. cepa cell cycle is 24 hours, so, application process was carried out for 24, 48, 72 and 96 hours. All the applied doses decreased MIs compared to control group and these declines were found to be statistically meaningful. Analysis of the chromosomes showed that 10 ppm IM except for 48 h induced CAs but 40 ppm IM except for 72 h decreased CAs. DNA damage was found significantly higher in 20 and 40 ppm of IM compared to the control in comet assay. These results indicated that IM herbicide exhibits cytotoxic activity but not genotoxic activity (except 10 ppm) and induced DNA damage in a dose dependent manner in A. cepa root meristematic cells. PMID:25752428

  1. Influence of the circadian rhythm in cell division on radiation-induced mitotic delay in vivo

    SciTech Connect

    Rubin, N.H.

    1982-01-01

    Mitotic delay is described as a classical response to radiation; however, circadian rhythmicity in cell division in vivo has not been considered by many authors. The present study investigated the relation between fluctuations reported as mitotic delay and recovery in vivo and circadian oscillations in mitotic index in mouse corneal epithelium. One aspect involved single doses (approximately 600 rad) given to mice at different circadian stages. The normal circadian rhythm in cell division was never obliterated. Inhibition of mitosis was evident but unpredictable, ranging from 6 to 15 hr after irradiation. Recovery was evident only during the daily increase in mitotic index of controls. The classical interpretation of recovery from mitotic delay may be in an in vitro phenomenon not reflecting in vivo responses, which are apparently strongly circadian stage dependent. The second portion of the study demonstrated a dose-response effect on length of mitotic delay and, to a lesser extent, degree of recovery.

  2. [Hair shaft abnormalities].

    PubMed

    Itin, P H; Düggelin, M

    2002-05-01

    Hair shaft disorders may lead to brittleness and uncombable hair. In general the hair feels dry and lusterless. Hair shaft abnormalities may occur as localized or generalized disorders. Genetic predisposition or exogenous factors are able to produce and maintain hair shaft abnormalities. In addition to an extensive history and physical examination the most important diagnostic examination to analyze a hair shaft problem is light microscopy. Therapy of hair shaft disorders should focus to the cause. In addition, minimizing traumatic influences to hair shafts, such as dry hair with an electric dryer, permanent waves and dyes is important. A short hair style is more suitable for such patients with hair shaft disorders.

  3. Enhancement of spontaneous mitotic recombination by the meiotic mutant spo11-1 in Saccharomyces cerevisiae

    SciTech Connect

    Bruschi, C.V.; Esposito, M.S.

    1983-12-01

    Both nonreciprocal and reciprocal mitotic recombination are enhanced by the recessive mutant spo11-1, which was previously shown to affect meiosis by decreasing recombination and increasing nondisjunction. The mitotic effects are not distributed equally in all chromosomal regions. The genotypes of mitotic recombinants in spo11-1/spo11-1 diploid cells provide further evidence that widely spaced chromosomal markers undergo coincident conversion in mitosis.

  4. Past to Present: Undergrowth with Two Figures

    ERIC Educational Resources Information Center

    School Arts: The Art Education Magazine for Teachers, 2004

    2004-01-01

    This brief article describes the historical, cultural, and artistic elements of Vincent van Gogh's oil on canvas "Undergrowth with Two Figures" of 1980. The article concludes with questions for students to consider in relation to these aspects of the painting.

  5. Significant Figure Rules for General Arithmetic Functions.

    ERIC Educational Resources Information Center

    Graham, D. M.

    1989-01-01

    Provides some significant figure rules used in chemistry including the general theoretical basis; logarithms and antilogarithms; exponentiation (with exactly known exponents); sines and cosines; and the extreme value rule. (YP)

  6. Unilateral microfibrillar abnormalities in a case of asymmetric Marfan syndrome.

    PubMed Central

    Godfrey, M; Olson, S; Burgio, R G; Martini, A; Valli, M; Cetta, G; Hori, H; Hollister, D W

    1990-01-01

    The Marfan syndrome is a dominantly inherited connective-tissue disorder characterized by ocular, cardiovascular, and musculoskeletal abnormalities. Although the underlying biochemical and molecular defect(s) of this pleiotropic disease is currently unknown, we have consistently observed apparent diminished content of elastin-associated microfibrillar fibers accumulating in skin, or produced by cultured fibroblasts, from patients with the Marfan syndrome and have documented the cosegregation of these immunofluorescent abnormalities of microfibrillar fibers with the Marfan syndrome phenotype in family studies. Recently, an unusual patient has been described with unilateral phenotypic features of the Marfan syndrome, providing an unique opportunity to compare microfibrillar fibers and other connective-tissue components between the affected and nonaffected sides. In the present report, we demonstrate striking differences in apparent content of microfibrillar fibers, as determined by indirect immunofluorescence of skin and fibroblast cultures, that are revealed when multiple homologous samples derived from different sides of the patient's body are compared. In contrast, no differences in apparent content of type III collagen or in the biosynthesis and apparent structure of types I and III (pro)collagens were found. HLA types and chromosome heteromorphisms were identical in fibroblasts from both sides of the body, eliminating the formal possibility of chimerism and suggesting that a postzygotic mutation accounts for the asymmetric manifestation of the Marfan syndrome in this patient. The observation of striking decreases in microfibrillar fibers on the affected side of the body provides further evidence that abnormalities of this component of the elastic fiber system may be central to the pathogenesis and possibly the etiology of the Marfan syndrome. Images Figure 5 Figure 4 Figure 1 Figure 2 Figure 3 Figure 6 PMID:2180285

  7. The NIMA Kinase Is Required To Execute Stage-Specific Mitotic Functions after Initiation of Mitosis

    PubMed Central

    Govindaraghavan, Meera; Lad, Alisha A.

    2014-01-01

    The G2-M transition in Aspergillus nidulans requires the NIMA kinase, the founding member of the Nek kinase family. Inactivation of NIMA results in a late G2 arrest, while overexpression of NIMA is sufficient to promote mitotic events independently of cell cycle phase. Endogenously tagged NIMA-GFP has dynamic mitotic localizations appearing first at the spindle pole body and then at nuclear pore complexes before transitioning to within nuclei and the mitotic spindle and back at the spindle pole bodies at mitotic exit, suggesting that it functions sequentially at these locations. Since NIMA is indispensable for mitotic entry, it has been difficult to determine the requirement of NIMA for subaspects of mitosis. We show here that when NIMA is partially inactivated, although mitosis can be initiated, a proportion of cells fail to successfully generate two daughter nuclei. We further define the mitotic defects to show that normal NIMA function is required for the formation of a bipolar spindle, nuclear pore complex disassembly, completion of chromatin segregation, and the normal structural rearrangements of the nuclear envelope required to generate two nuclei from one. In the remaining population of cells that enter mitosis with inadequate NIMA, two daughter nuclei are generated in a manner dependent on the spindle assembly checkpoint, indicating highly penetrant defects in mitotic progression without sufficient NIMA activity. This study shows that NIMA is required not only for mitotic entry but also sequentially for successful completion of stage-specific mitotic events. PMID:24186954

  8. Delaying mitotic exit downregulates FLIP expression and strongly sensitizes tumor cells to TRAIL.

    PubMed

    Sánchez-Pérez, T; Medema, R H; López-Rivas, A

    2015-01-29

    Many of the current antitumor therapeutic strategies are based on the perturbation of the cell cycle, especially during mitosis. Antimitotic drugs trigger mitotic checkpoint activation, mitotic arrest and eventually cell death. However, mitotic slippage represents a major mechanism of resistance to these treatments. In an attempt to circumvent the process of slippage, targeting mitotic exit has been proposed as a better strategy to kill tumor cells. In this study, we show that treatments that induce mitotic checkpoint activation and mitotic arrest downregulate FLICE-like inhibitory protein (FLIP) levels and sensitize several tumor cell lines to TRAIL (tumor necrosis factor-related apoptosis-inducing ligand)-induced apoptosis. Interestingly, we also demonstrate that in absence of mitotic checkpoint activation, mitotic arrest induced either by Cdc20 knockdown or overexpression of nondegradable cyclin B is sufficient to induce both FLIP downregulation and sensitivity to TRAIL. In summary, our data suggest that a combination of antimitotic drugs targeting cyclin B degradation and TRAIL might prevent mitotic slippage and allow tumor cells to reach the threshold for apoptosis induction, thereby facilitating tumor suppression. PMID:24488010

  9. Evolution of the Significant Figure Rules

    NASA Astrophysics Data System (ADS)

    Carter, Ashley R.

    2013-09-01

    Today, almost all introductory physics textbooks include standardized "rules" on how to find the number of significant figures in a calculated value. And yet, 30 years ago these rules were almost nonexistent. Whyhave we increased the role of significant figures in introductory classes, and should we continue this trend? A look back at the evolution of significant figures over the last 300 years, from Newton to Millikan to modern authors, sheds some light on their purpose moving forward. While there is much discussion for and against their use, especially in chemistry, a review of earlier versions of the rules suggests that we have lost some items of value, most notably, a significant figure rule for angles. In addition, we have lost the emphasis that the significant figure rules were designed to calculate an approximate (not exact) precision. Now that the significant figure rules are ingrained into our introductory physics sequence, we would be wise to reiterate that these are just general "rules of thumb."

  10. Maytansinoid-antibody conjugates induce mitotic arrest by suppressing microtubule dynamic instability.

    PubMed

    Oroudjev, Emin; Lopus, Manu; Wilson, Leslie; Audette, Charlene; Provenzano, Carmela; Erickson, Hans; Kovtun, Yelena; Chari, Ravi; Jordan, Mary Ann

    2010-10-01

    Maytansine and its analogues (maytansinoids) are potent microtubule-targeted compounds that inhibit proliferation of cells at mitosis. Antibody-maytansinoid conjugates consisting of maytansinoids (DM1 and DM4) attached to tumor-specific antibodies have shown promising clinical results. To determine the mechanism by which the antibody-DM1 conjugates inhibit cell proliferation, we examined the effects of the cleavable anti-EpCAM-SPP-DM1 and uncleavable anti-EpCAM-SMCC-DM1 conjugates on MCF7 human breast tumor cells. We also examined the effects of the free maytansinoids, maytansine and S-methyl DM1 (a version of DM1 that is stable in cell culture medium), for comparison. Both the conjugates and free maytansinoids potently inhibited MCF7 cell proliferation at nanomolar and subnanomolar concentrations, respectively, by arresting the cells in mitotic prometaphase/metaphase. Arrest occurred in concert with the internalization and intracellular processing of both conjugates under conditions that induced abnormal spindle organization and suppressed microtubule dynamic instability. Microtubule depolymerization occurred only at significantly higher drug concentrations. The results indicate that free maytansinoids, antibody-maytansinoid conjugates, and their metabolites exert their potent antimitotic effects through a common mechanism involving suppression of microtubule dynamic instability.

  11. Chromosomal instability, tolerance of mitotic errors and multidrug resistance are promoted by tetraploidization in human cells

    PubMed Central

    Kuznetsova, Anastasia Y; Seget, Katarzyna; Moeller, Giuliana K; de Pagter, Mirjam S.; de Roos, Jeroen A D M; Dürrbaum, Milena; Kuffer, Christian; Müller, Stefan; Zaman, Guido J R; Kloosterman, Wigard P; Storchová, Zuzana

    2015-01-01

    Up to 80% of human cancers, in particular solid tumors, contain cells with abnormal chromosomal numbers, or aneuploidy, which is often linked with marked chromosomal instability. Whereas in some tumors the aneuploidy occurs by missegregation of one or a few chromosomes, aneuploidy can also arise during proliferation of inherently unstable tetraploid cells generated by whole genome doubling from diploid cells. Recent findings from cancer genome sequencing projects suggest that nearly 40% of tumors underwent whole genome doubling at some point of tumorigenesis, yet its contribution to cancer phenotypes and benefits for malignant growth remain unclear. Here, we investigated the consequences of a whole genome doubling in both cancerous and non-transformed p53 positive human cells. SNP array analysis and multicolor karyotyping revealed that induced whole-genome doubling led to variable aneuploidy. We found that chromosomal instability (CIN) is a frequent, but not a default outcome of whole genome doubling. The CIN phenotypes were accompanied by increased tolerance to mitotic errors that was mediated by suppression of the p53 signaling. Additionally, the expression of pro-apoptotic factors, such as iASPP and cIAP2, was downregulated. Furthermore, we found that whole genome doubling promotes resistance to a broad spectrum of chemotherapeutic drugs and stimulates anchorage-independent growth even in non-transformed p53-positive human cells. Taken together, whole genome doubling provides multifaceted benefits for malignant growth. Our findings provide new insight why genome-doubling promotes tumorigenesis and correlates with poor survival in cancer. PMID:26151317

  12. Mitotic and meiotic behavior of rye chromosomes in wheat - Psathyrostachys huashanica amphiploid x triticale progeny.

    PubMed

    Xie, Q; Kang, H; Sparkes, D L; Tao, S; Fan, X M; Xu, L; Fan, X; Sha, L; Zhang, H; Wang, Y; Zeng, J; Zhou, Y

    2013-07-24

    The dynamics of rye chromosomes during mitosis and meiosis was analyzed in a subset comprising 33 F3 lines from the cross of wheat, Psathyrostachys huashanica amphiploid (AABBDDNsNs) and hexaploid triticale (AABBRR), as visualized by genomic in situ hybridization. The results indicated that 31 of the total lines contained 4-14 rye chromosomes. Twenty-eight combinations had more rye chromosomes than the F1 hybrids, suggesting the occurrence of spontaneous quantitative increment. No P. huashanica chromosomes were detected in all of the combinations tested. Mitotic analysis showed that rye chromosomes progressed normally with the wheat counterparts without loss. However, abnormal meiosis was found in almost all lines. Similar progression between wheat and rye genomes appeared from interphase to metaphase I. It was at anaphase I that many rye univalents lagged behind those of wheat, followed by equational division. This resulted in the formation of chromosomal segments and micronuclei at telophase I or II. Micronuclei could also be generated from the immobilized univalents in the periphery of cells. Synapsis and translocations between wheat and rye genomes, chromosome bridges, and unreduced gametes were detected. Therefore, it is proposed that rye chromosome elimination may involve chromatid lagging, fragmentation and micronucleation, or the immobilization of certain univalents during meiosis instead of mitosis in the relatively advanced generations. This mechanism, together with spontaneous incremental increase of rye chromosome number, permitted the generation of various germplasms for wheat improvement.

  13. Non-anti-mitotic concentrations of taxol reduce breast cancer cell invasiveness

    SciTech Connect

    Tran, Truong-An; Gillet, Ludovic; Roger, Sebastien; Besson, Pierre; White, Edward; Le Guennec, Jean-Yves

    2009-02-06

    Taxol is widely used in breast cancer chemotherapy. Its effects are primarily attributed to its anti-mitotic activity. Microtubule perturbators also exert antimetastatic activities which cannot be explained solely by the inhibition of proliferation. Voltage-dependent sodium channels (Na{sub V}) are abnormally expressed in the highly metastatic breast cancer cell line MDA-MB-231 and not in MDA-MB-468 cell line. Inhibiting Na{sub V} activity with tetrodotoxin is responsible for an approximately 0.4-fold reduction of MDA-MB-231 cell invasiveness. In this study, we focused on the effect of a single, 2-h application of 10 nM taxol on the two cell lines MDA-MB-231 and MDA-MB-468. At this concentration, taxol had no effect on proliferation after 7 days and on migration in any cell line. However it led to a 40% reduction of transwell invasion of MDA-MB-231 cells. There was no additive effect when taxol and tetrodotoxin were simultaneously applied. Na{sub V} activity, as assessed by patch-clamp, indicates that it was changed by taxol pre-treatment. We conclude that taxol can exert anti-tumoral activities, in cells expressing Na{sub V}, at low doses that have no effect on cell proliferation. This effect might be due to a modulation of signalling pathways involving sodium channels.

  14. Extracellular Tau Paired Helical Filaments Differentially Affect Tau Pathogenic Mechanisms in Mitotic and Post-Mitotic Cells: Implications for Mechanisms of Tau Propagation in the Brain.

    PubMed

    Varghese, Merina; Santa-Maria, Ismael; Ho, Lap; Ward, Libby; Yemul, Shrishailam; Dubner, Lauren; Księżak-Reding, Hanna; Pasinetti, Giulio Maria

    2016-09-01

    The release of paired helical filaments (PHFs) from neurons into the extracellular space may contribute to the propagation of tau pathology across brain regions in Alzheimer's disease (AD) and other tauopathies. The majority of available mechanistic studies exploring the pathologic role of extracellular PHFs are conducted in proliferating cell lines. Here, we compare how extracellular PHFs induce tauopathy in mitotic cells and in post-mitotic brain neurons. In a mitotic cell line (HEK 293T), extracellular exposure to AD PHFs leads to an intracellular "aggresomal" type deposition of tau, coincidental with redistribution of dynein, a retrograde motor protein. We also observed that PHFs impaired proteasome degradation, but not autophagy. Exposure of cells to proteasome inhibitors was sufficient to induce intracellular tau aggregate formation as well as reorganization of dynein and the intermediate filament protein, vimentin. Thus, in mitotic cells, extracellular PHFs promote cellular tau aggregation, in part, by interfering with cellular proteasome degradation processes. In contrast with our observations with proliferating cells, exposure of post-mitotic primary neuronal cultures to AD PHFs did not promote "aggresomal" tau deposition, but instead resulted in a widespread accumulation of phosphorylated tau-immunoreactive swellings in neuritic processes, characterized by disturbed cytoskeletal organization of dynein and vimentin. Collectively, our observations suggest that extracellular PHFs may contribute to the propagation of tau pathology by independent mechanisms in post-mitotic and mitotic brain cells. These outcomes indicate that in addition to post-mitotic brain neurons, mitotic brain cells should also be considered as targets for therapeutic interventions to attenuate propagation of tauopathy.

  15. The p90 ribosomal S6 kinase 2 specifically affects mitotic progression by regulating the basal level, distribution and stability of mitotic spindles

    PubMed Central

    Park, Yun Yeon; Nam, Hyun-Ja; Do, Mihyang; Lee, Jae-Ho

    2016-01-01

    RSK2, also known as RPS6KA3 (ribosomal protein S6 kinase, 90 kDa, polypeptide 3), is a downstream kinase of the mitogen-activated protein kinase (MAPK) pathway, which is important in regulating survival, transcription, growth and proliferation. However, its biological role in mitotic progression is not well understood. In this study, we examined the potential involvement of RSK2 in the regulation of mitotic progression. Interestingly, depletion of RSK2, but not RSK1, caused the accumulation of mitotic cells. Time-lapse analysis revealed that mitotic duration, particularly the duration for metaphase-to-anaphase transition was prolonged in RSK2-depleted cells, suggesting activation of spindle assembly checkpoint (SAC). Indeed, more BubR1 (Bub1-related kinase) was present on metaphase plate kinetochores in RSK2-depleted cells, and depletion of BubR1 abolished the mitotic accumulation caused by RSK2 depletion, confirming BubR1-dependent SAC activation. Along with the shortening of inter-kinetochore distance, these data suggested that weakening of the tension across sister kinetochores by RSK2 depletion led to the activation of SAC. To test this, we analyzed the RSK2 effects on the stability of kinetochore–microtubule interactions, and found that RSK2-depleted cells formed less kinetochore–microtubule fibers. Moreover, RSK2 depletion resulted in the decrease of basal level of microtubule as well as an irregular distribution of mitotic spindles, which might lead to observed several mitotic progression defects such as increase in unaligned chromosomes, defects in chromosome congression and a decrease in pole-to-pole distance in these cells. Taken together, our data reveal that RSK2 affects mitotic progression by regulating the distribution, basal level and the stability of mitotic spindles. PMID:27491410

  16. The Distribution of Active Force Generators Controls Mitotic Spindle Position

    NASA Astrophysics Data System (ADS)

    Grill, Stephan W.; Howard, Jonathon; Schäffer, Erik; Stelzer, Ernst H. K.; Hyman, Anthony A.

    2003-07-01

    During unequal cell divisions a mitotic spindle is eccentrically positioned before cell cleavage. To determine the basis of the net force imbalance that causes spindle displacement in one-cell Caenorhabditis elegans embryos, we fragmented centrosomes with an ultraviolet laser. Analysis of the mean and variance of fragment speeds suggests that the force imbalance is due to a larger number of force generators pulling on astral microtubules of the posterior aster relative to the anterior aster. Moreover, activation of heterotrimeric guanine nucleotide-binding protein (G protein) α subunits is required to generate these astral forces.

  17. CamKII inhibitors reduce mitotic instability, connexon anomalies and progression of the in vivo behavioral phenotype in transgenic animals expressing a mutated Gjb1 gene.

    PubMed

    Mones, Saleh; Bordignon, Benoit; Peiretti, Franck; Landrier, Jean F; Gess, Burkhardt; Bourguignon, Jean J; Bihel, Frédéric; Fontés, Michel

    2014-01-01

    Mutation in the Gjb1 gene, coding for a connexin (Cx32), is associated with an inherited peripheral neuropathic disorder (X-linked Charcot-Marie-Tooth, CMTX). Our previous work reported that transgenic animals expressing a human Gjb1 transgene present polyploidy and abnormal over-duplication of the centrosome, suggesting a role for Gjb1 in mitotic stability. In this article, we propose mechanisms by which mutations in Gjb1 induce mitotic instability and discuss its potential relation with the CMTX phenotype. We showed that transgenic cells exhibit CamKII over-stimulation, a phenomenon that has been linked to mitotic instability (polyploidy, nuclear volume and centrosome over-duplication), that is reversed by CamKII inhibitors. We also demonstrate that connexon activity is partially restored in transgenic cells with CamKII inhibitors. Our model supports the role for Pim1, a kinase that has been associated with genomic instability in cancers, in genomic instability in Cx32 mutations. Regarding in vivo phenotype, we showed that degradation on the rotarod test in our transgenic mice is significantly lowered by treatment with a CamKII inhibitor (KN93). This effect was seen in two lines with different point mutations in GJB1, and stopping the treatment led to degradation of the phenotype. PMID:24982612

  18. Wet-Etch Figuring Optical Figuring by Controlled Application of Liquid Etchant

    SciTech Connect

    Britten, J

    2001-02-13

    WET-ETCH FIGURING (WEF) is an automated method of precisely figuring optical materials by the controlled application of aqueous etchant solution. This technology uses surface-tension-gradient-driven flow to confine and stabilize a wetted zone of an etchant solution or other aqueous processing fluid on the surface of an object. This wetted zone can be translated on the surface in a computer-controlled fashion for precise spatial control of the surface reactions occurring (e.g. chemical etching). WEF is particularly suitable for figuring very thin optical materials because it applies no thermal or mechanical stress to the material. Also, because the process is stress-free the workpiece can be monitored during figuring using interferometric metrology, and the measurements obtained can be used to control the figuring process in real-time--something that cannot be done with traditional figuring methods.

  19. Sodium azide induces mitotic recombination in Drosophila melanogaster larvae.

    PubMed

    González-César, E; Ramos-Morales, P

    1997-03-17

    Sodium azide (NaN3), a potent mutagen for bacteria and barley, was tested for somatic mutation and mitotic recombination induction in wing imaginal disc cells of Drosophila melanogaster. Comparisons were made among inversion-free flr3/mwh, inversion-heterozygous TM3, Ser/mwh, and inversion-free, high bioactivation OR(R), flr3/mwh flies. Third instar larvae were exposed chronically for 48 h to sodium azide at 0.5, 0.63, 0.75, 0.88 and 1.0 mM. The frequencies of spots per wing obtained in the three kinds of progeny scored were compared. In inversion-free flies, sodium azide induced large single and total spots at all concentrations tested, and small single and twin spots at 0.75 mM and higher concentrations. In contrast, it failed to increase the frequency of small and large single spots in inversion-heterozygous flies. In high bioactivation flies (which are inversion-free), sodium azide increased the frequency of large single spots at 0.63, 0.88 and 1.0 mM and the frequency of total spots at 0.63 mM. From the absence of genotoxic activity observed in inversion-heterozygous flies it is concluded that sodium azide induces exclusively mitotic recombination in wing somatic cells of Drosophila melanogaster larvae after chronic exposure. This recombinogenic activity is reduced in the presence of high bioactivation capacity.

  20. Unconventional Functions of Mitotic Kinases in Kidney Tumorigenesis

    PubMed Central

    Hascoet, Pauline; Chesnel, Franck; Le Goff, Cathy; Le Goff, Xavier; Arlot-Bonnemains, Yannick

    2015-01-01

    Human tumors exhibit a variety of genetic alterations, including point mutations, translocations, gene amplifications and deletions, as well as aneuploid chromosome numbers. For carcinomas, aneuploidy is associated with poor patient outcome for a large variety of tumor types, including breast, colon, and renal cell carcinoma. The Renal cell carcinoma (RCC) is a heterogeneous carcinoma consisting of different histologic types. The clear renal cell carcinoma (ccRCC) is the most common subtype and represents 85% of the RCC. Central to the biology of the ccRCC is the loss of function of the Von Hippel–Lindau gene, but is also associated with genetic instability that could be caused by abrogation of the cell cycle mitotic spindle checkpoint and may involve the Aurora kinases, which regulate centrosome maturation. Aneuploidy can also result from the loss of cell–cell adhesion and apical–basal cell polarity that also may be regulated by the mitotic kinases (polo-like kinase 1, casein kinase 2, doublecortin-like kinase 1, and Aurora kinases). In this review, we describe the “non-mitotic” unconventional functions of these kinases in renal tumorigenesis. PMID:26579493

  1. Inhibition of mitotic-specific histone phophorylation by sodium arsenite

    SciTech Connect

    Cobo, J.M.; Valdez, J.G.; Gurley, L.R.

    1994-10-01

    Synchronized cultures of Chinese hamster cells (line CHO) were used to measure the effects of 10{mu}M sodium arsenite on histone phosphorylation. This treatment caused cell proliferation to be temporarily arrested, after which the cells spontaneously resumed cell proliferation in a radiomimetric manner. Immediately following treatment, it was found that sodium arsenite affected only mitotic-specific HI and H3 phosphorylations. Neither interphase, nor mitotic, H2A and H4 phosphorylations were affected, nor was interphase HI Phosphorylation affected. The phosphorylation of HI was inhibited only in mitosis, reducing HI phosphorylation to 38.1% of control levels, which was the level of interphase HI phosphorylation. The phosphorylation of both H3 variants was inhibited in mitosis, the less hydrophobic H3 to 19% and the more hydrophobic H3 to 24% of control levels. These results suggest that sodium arsenite may inhibite cell proliferation by interfering with the cyclin B/p34{sup cdc2} histone kinase activity which is thought to play a key role in regulating the cell cycle. It has been proposed by our laboratory that HI and H3 phosphorylations play a role in restructuring interphase chromatin into metaphase chromosomes. Interference of this process by sodium arsenite may lead to structurally damaged chromosomes resulting in the increased cancer risks known to be produced by arsenic exposure from the environment.

  2. Haspin: a newly discovered regulator of mitotic chromosome behavior

    PubMed Central

    2010-01-01

    The haspins are divergent members of the eukaryotic protein kinase family that are conserved in many eukaryotic lineages including animals, fungi, and plants. Recently-solved crystal structures confirm that the kinase domain of human haspin has unusual structural features that stabilize a catalytically active conformation and create a distinctive substrate binding site. Haspin localizes predominantly to chromosomes and phosphorylates histone H3 at threonine-3 during mitosis, particularly at inner centromeres. This suggests that haspin directly regulates chromosome behavior by modifying histones, although it is likely that additional substrates will be identified in the future. Depletion of haspin by RNA interference in human cell lines causes premature loss of centromeric cohesin from chromosomes in mitosis and failure of metaphase chromosome alignment, leading to activation of the spindle assembly checkpoint and mitotic arrest. Haspin overexpression stabilizes chromosome arm cohesion. Haspin, therefore, appears to be required for protection of cohesion at mitotic centromeres. Saccharomyces cerevisiae homologues of haspin, Alk1 and Alk2, are also implicated in regulation of mitosis. In mammals, haspin is expressed at high levels in the testis, particularly in round spermatids, so it seems likely that haspin has an additional role in post-meiotic spermatogenesis. Haspin is currently the subject of a number of drug discovery efforts, and the future use of haspin inhibitors should provide new insight into the cellular functions of these kinases and help determine the utility of, for example, targeting haspin for cancer therapy. PMID:19997740

  3. Towards a quantitative understanding of mitotic spindle assembly and mechanics

    PubMed Central

    Mogilner, Alex; Craig, Erin

    2010-01-01

    The ‘simple’ view of the mitotic spindle is that it self-assembles as a result of microtubules (MTs) randomly searching for chromosomes, after which the spindle length is maintained by a balance of outward tension exerted by molecular motors on the MTs connecting centrosomes and chromosomes, and compression generated by other motors on the MTs connecting the spindle poles. This picture is being challenged now by mounting evidence indicating that spindle assembly and maintenance rely on much more complex interconnected networks of microtubules, molecular motors, chromosomes and regulatory proteins. From an engineering point of view, three design principles of this molecular machine are especially important: the spindle assembles quickly, it assembles accurately, and it is mechanically robust – yet malleable. How is this design achieved with randomly interacting and impermanent molecular parts? Here, we review recent interdisciplinary studies that have started to shed light on this question. We discuss cooperative mechanisms of spindle self-assembly, error correction and maintenance of its mechanical properties, speculate on analogy between spindle and lamellipodial dynamics, and highlight the role of quantitative approaches in understanding the mitotic spindle design. PMID:20930139

  4. Function and regulation of dynein in mitotic chromosome segregation.

    PubMed

    Raaijmakers, J A; Medema, R H

    2014-10-01

    Cytoplasmic dynein is a large minus-end-directed microtubule motor complex, involved in many different cellular processes including intracellular trafficking, organelle positioning, and microtubule organization. Furthermore, dynein plays essential roles during cell division where it is implicated in multiple processes including centrosome separation, chromosome movements, spindle organization, spindle positioning, and mitotic checkpoint silencing. How is a single motor able to fulfill this large array of functions and how are these activities temporally and spatially regulated? The answer lies in the unique composition of the dynein motor and in the interactions it makes with multiple regulatory proteins that define the time and place where dynein becomes active. Here, we will focus on the different mitotic processes that dynein is involved in, and how its regulatory proteins act to support dynein. Although dynein is highly conserved amongst eukaryotes (with the exception of plants), there is significant variability in the cellular processes that depend on dynein in different species. In this review, we concentrate on the functions of cytoplasmic dynein in mammals but will also refer to data obtained in other model organisms that have contributed to our understanding of dynein function in higher eukaryotes.

  5. Small Molecule Approach to Study the Function of Mitotic Kinesins.

    PubMed

    Al-Obaidi, Naowras; Kastl, Johanna; Mayer, Thomas U

    2016-01-01

    Mitotic motor proteins of the kinesin superfamily are critical for the faithful segregation of chromosomes and the formation of the two daughter cells during meiotic and mitotic M-phase. Of the 45 human kinesins, roughly a dozen are involved in the assembly of the bipolar spindle, alignment of chromosomes at the spindle equator, chromosome segregation, and cytokinesis. The functions of kinesins in these processes are highly diverse and include the transport of cargo molecules, sliding and bundling of microtubules, and regulation of microtubule dynamics. In light of this multitude of diverse functions and the complex functional interplay of different kinesins during M-phase, it is not surprising that one of the greatest challenges in cell biology is the functional dissection of individual motor proteins. Reversible and fast acting small molecules are powerful tools to accomplish this challenge. However, the validity of conclusions drawn from small molecule studies strictly depends on compound specificity. In this chapter, we present methods for the identification of small molecule inhibitors of a motor protein of interest. In particular, we focus on a protein-based large throughput screen to identify inhibitors of the ATPase activity of kinesins. Furthermore, we provide protocols and guidelines for secondary screens to validate hits and select for specific inhibitors. PMID:27193856

  6. On psychoanalytic figures as transference objects.

    PubMed

    Spurling, Laurence

    2003-02-01

    One of the tasks that analysts and therapists face at a certain stage in their career is how to develop a way of psychoanalytic thinking and practising of their own. To do this involves modifying or overcoming the transferences established during their training or early career. These transferences are to one's teachers or training analyst, investing them with authority and infallibility, and to received theory, which is treated as though it were dogma. The need to free oneself from such transferences has been discussed in the literature. There is, however, another kind of transference that the developing therapist also needs to resolve, which has received little attention. This is the transference made on to a key figure in the psychoanalytic tradition. Such a psychoanalytic figure will be seen as the originator of or embodiment of those theoretical ideas to which one becomes attached, and/or as standing behind one's training analyst or seminal teachers who become a representative of that figure. The value of an investigation of one's relationship to a psychoanalytic figure is that it is an excellent medium for revealing one's transference, as the figure in question is not a real person but only exists through his/her writings. The body of the paper consists of an extended example of such an analysis, that of my own transference on to the figure of Winnicott. In this example I illustrate how my evaluation of Winnicott's ideas changed from seeing them as providing answers to all my clinical questions to no longer satisfying me in some areas of my work. This change in my relationship to Winnicott's theory went hand in hand with a modification in my transference on to the figure of Winnicott, from seeing him as endowed with authority and goodness to an appreciation of him as a still sustaining figure but now with limits and flaws. In the final part of the paper several questions arising out of my analysis are posed. Can the pull of writing such an account in terms of

  7. Morphological abnormalities in elasmobranchs.

    PubMed

    Moore, A B M

    2015-08-01

    A total of 10 abnormal free-swimming (i.e., post-birth) elasmobranchs are reported from The (Persian-Arabian) Gulf, encompassing five species and including deformed heads, snouts, caudal fins and claspers. The complete absence of pelvic fins in a milk shark Rhizoprionodon acutus may be the first record in any elasmobranch. Possible causes, including the extreme environmental conditions and the high level of anthropogenic pollution particular to The Gulf, are briefly discussed.

  8. Mitotic activity and delay in fixation of tumour tissue. The influence of delay in fixation on mitotic activity of a human osteogenic sarcoma grown in athymic nude mice.

    PubMed

    Graem, N; Helweg-Larsen, K

    1979-09-01

    The purpose of the present investigation was to study the effect of delay in fixation on the mitotic activity in tumour tissue. A human osteogenic sarcoma, especially suitable for counting of mitoses, grown in athymic nude mice, was fixed with varying delay and the mitotic, prophase, metaphase and ana-telophase indices were determined. An almost exponential decline of the mitotic index was observed with a reduction to 49.4% and 15.0% after respectively 60 and 180 minutes. The proportional incidence of prophases, metaphases and ana-telophases changed so that a relative accummulation of advanced phases occured during the 180 minutes of observation. It is concluded that delay in fixation of a magnitude, which is not uncommon in routine surgical pathology, may allow the majority of mitoses to terminate, resulting in unreliable assessments of mitotic activity.

  9. Chromosome abnormalities in glioma

    SciTech Connect

    Li, Y.S.; Ramsay, D.A.; Fan, Y.S.

    1994-09-01

    Cytogenetic studies were performed in 25 patients with gliomas. An interesting finding was a seemingly identical abnormality, an extra band on the tip of the short arm of chromosome 1, add(1)(p36), in two cases. The abnormality was present in all cells from a patient with a glioblastoma and in 27% of the tumor cells from a patient with a recurrent irradiated anaplastic astrocytoma; in the latter case, 7 unrelated abnormal clones were identified except 4 of those clones shared a common change, -Y. Three similar cases have been described previously. In a patient with pleomorphic astrocytoma, the band 1q42 in both homologues of chromosome 1 was involved in two different rearrangements. A review of the literature revealed that deletion of the long arm of chromosome 1 including 1q42 often occurs in glioma. This may indicate a possible tumor suppressor gene in this region. Cytogenetic follow-up studies were carried out in two patients and emergence of unrelated clones were noted in both. A total of 124 clonal breakpoints were identified in the 25 patients. The breakpoints which occurred three times or more were: 1p36, 1p22, 1q21, 1q25, 3q21, 7q32, 8q22, 9q22, 16q22, and 22q13.

  10. [Congenital foot abnormalities].

    PubMed

    Delpont, M; Lafosse, T; Bachy, M; Mary, P; Alves, A; Vialle, R

    2015-03-01

    The foot may be the site of birth defects. These abnormalities are sometimes suspected prenatally. Final diagnosis depends on clinical examination at birth. These deformations can be simple malpositions: metatarsus adductus, talipes calcaneovalgus and pes supinatus. The prognosis is excellent spontaneously or with a simple orthopedic treatment. Surgery remains outstanding. The use of a pediatric orthopedist will be considered if malposition does not relax after several weeks. Malformations (clubfoot, vertical talus and skew foot) require specialized care early. Clubfoot is characterized by an equine and varus hindfoot, an adducted and supine forefoot, not reducible. Vertical talus combines equine hindfoot and dorsiflexion of the forefoot, which is performed in the midfoot instead of the ankle. Skew foot is suspected when a metatarsus adductus is resistant to conservative treatment. Early treatment is primarily orthopedic at birth. Surgical treatment begins to be considered after walking age. Keep in mind that an abnormality of the foot may be associated with other conditions: malposition with congenital hip, malformations with syndromes, neurological and genetic abnormalities. PMID:25524290

  11. Software systems for modeling articulated figures

    NASA Technical Reports Server (NTRS)

    Phillips, Cary B.

    1989-01-01

    Research in computer animation and simulation of human task performance requires sophisticated geometric modeling and user interface tools. The software for a research environment should present the programmer with a powerful but flexible substrate of facilities for displaying and manipulating geometric objects, yet insure that future tools have a consistent and friendly user interface. Jack is a system which provides a flexible and extensible programmer and user interface for displaying and manipulating complex geometric figures, particularly human figures in a 3D working environment. It is a basic software framework for high-performance Silicon Graphics IRIS workstations for modeling and manipulating geometric objects in a general but powerful way. It provides a consistent and user-friendly interface across various applications in computer animation and simulation of human task performance. Currently, Jack provides input and control for applications including lighting specification and image rendering, anthropometric modeling, figure positioning, inverse kinematics, dynamic simulation, and keyframe animation.

  12. Abnormal pressures as hydrodynamic phenomena

    USGS Publications Warehouse

    Neuzil, C.E.

    1995-01-01

    So-called abnormal pressures, subsurface fluid pressures significantly higher or lower than hydrostatic, have excited speculation about their origin since subsurface exploration first encountered them. Two distinct conceptual models for abnormal pressures have gained currency among earth scientists. The static model sees abnormal pressures generally as relict features preserved by a virtual absence of fluid flow over geologic time. The hydrodynamic model instead envisions abnormal pressures as phenomena in which flow usually plays an important role. This paper develops the theoretical framework for abnormal pressures as hydrodynamic phenomena, shows that it explains the manifold occurrences of abnormal pressures, and examines the implications of this approach. -from Author

  13. Timely Endocytosis of Cytokinetic Enzymes Prevents Premature Spindle Breakage during Mitotic Exit

    PubMed Central

    Onishi, Masayuki; Yeong, Foong May

    2016-01-01

    Cytokinesis requires the spatio-temporal coordination of membrane deposition and primary septum (PS) formation at the division site to drive acto-myosin ring (AMR) constriction. It has been demonstrated that AMR constriction invariably occurs only after the mitotic spindle disassembly. It has also been established that Chitin Synthase II (Chs2p) neck localization precedes mitotic spindle disassembly during mitotic exit. As AMR constriction depends upon PS formation, the question arises as to how chitin deposition is regulated so as to prevent premature AMR constriction and mitotic spindle breakage. In this study, we propose that cells regulate the coordination between spindle disassembly and AMR constriction via timely endocytosis of cytokinetic enzymes, Chs2p, Chs3p, and Fks1p. Inhibition of endocytosis leads to over accumulation of cytokinetic enzymes during mitotic exit, which accelerates the constriction of the AMR, and causes spindle breakage that eventually could contribute to monopolar spindle formation in the subsequent round of cell division. Intriguingly, the mitotic spindle breakage observed in endocytosis mutants can be rescued either by deleting or inhibiting the activities of, CHS2, CHS3 and FKS1, which are involved in septum formation. The findings from our study highlight the importance of timely endocytosis of cytokinetic enzymes at the division site in safeguarding mitotic spindle integrity during mitotic exit. PMID:27447488

  14. Metrics of Justice. A Sundial's Nomological Figuration.

    PubMed

    Behrmann, Carolin

    2015-01-01

    This paper examines a polyhedral dial from the British Museum made by the instrument maker Ulrich Schniep, and discusses the status of multifunctional scientific instruments. It discerns a multifaceted iconic meaning considering different dimensions such as scientific functionality (astronomy), the complex allegorical figure of Justice (iconography), and the representation of the sovereign (politics), the court and the Kunstkammer of Albrecht v of Bavaria. As a numen mixtum the figure of "Justicia" touches different fields that go far beyond pure astronomical measurement and represents the power of the ruler as well as the rules of economic justice.

  15. [Figures of anima in the Odyssey].

    PubMed

    Meneghello, Mauro

    2012-01-01

    Feminine characters in the Odyssey show different aspects of the archetype: Mother and Anima (C.G. Jung). From an Analytical Psychology perspective the encounters of Odysseus with goddesses: Circe, Calypso, Ino are looked at as different and successive stages of the hero's way into the inconscious, who shows himself in feminine figures, being masculine the consciousness of the hero. Nausicaa is a new, nearly-human figure of Anima who appears after the symbolic death of Odysseus and leads him to the royal couple Alcinous-Arete: in front of them all he finds his new, reborn, personality by creating and narrating his own myth.

  16. [Figures of anima in the Odyssey].

    PubMed

    Meneghello, Mauro

    2012-01-01

    Feminine characters in the Odyssey show different aspects of the archetype: Mother and Anima (C.G. Jung). From an Analytical Psychology perspective the encounters of Odysseus with goddesses: Circe, Calypso, Ino are looked at as different and successive stages of the hero's way into the inconscious, who shows himself in feminine figures, being masculine the consciousness of the hero. Nausicaa is a new, nearly-human figure of Anima who appears after the symbolic death of Odysseus and leads him to the royal couple Alcinous-Arete: in front of them all he finds his new, reborn, personality by creating and narrating his own myth. PMID:25807734

  17. Feeling Abnormal: Simulation of Deviancy in Abnormal and Exceptionality Courses.

    ERIC Educational Resources Information Center

    Fernald, Charles D.

    1980-01-01

    Describes activity in which student in abnormal psychology and psychology of exceptional children classes personally experience being judged abnormal. The experience allows the students to remember relevant research, become sensitized to the feelings of individuals classified as deviant, and use caution in classifying individuals as abnormal.…

  18. Human KIAA1018/FAN1 nuclease is a new mitotic substrate of APC/CCdh1

    PubMed Central

    Lai, Fenju; Hu, Kaishun; Wu, Yuanzhong; Tang, Jianjun; Sang, Yi; Cao, Jingying; Kang, Tiebang

    2012-01-01

    A recently identified protein, FAN1 (FANCD2-associated nuclease 1, previously known as KIAA1018), is a novel nuclease associated with monoubiquitinated FANCD2 that is required for cellular resistance against DNA interstrand crosslinking (ICL) agents. The mechanisms of FAN1 regulation have not yet been explored. Here, we provide evidence that FAN1 is degraded during mitotic exit, suggesting that FAN1 may be a mitotic substrate of the anaphase-promoting cyclosome complex (APC/C). Indeed, Cdh1, but not Cdc20, was capable of regulating the protein level of FAN1 through the KEN box and the D-box. Moreover, the up- and down-regulation of FAN1 affected the progression to mitotic exit. Collectively, these data suggest that FAN1 may be a new mitotic substrate of APC/CCdh1 that plays a key role during mitotic exit. PMID:22854063

  19. On generating cell exemplars for detection of mitotic cells in breast cancer histopathology images.

    PubMed

    Aloraidi, Nada A; Sirinukunwattana, Korsuk; Khan, Adnan M; Rajpoot, Nasir M

    2014-01-01

    Mitotic activity is one of the main criteria that pathologists use to decide the grade of the cancer. Computerised mitotic cell detection promises to bring efficiency and accuracy into the grading process. However, detection and classification of mitotic cells in breast cancer histopathology images is a challenging task because of the large intra-class variation in the visual appearance of mitotic cells in various stages of cell division life cycle. In this paper, we test the hypothesis that cells in histopathology images can be effectively represented using cell exemplars derived from sub-images of various kinds of cells in an image for the purposes of mitotic cell classification. We compare three methods for generating exemplar cells. The methods have been evaluated in terms of classification performance on the MITOS dataset. The experimental results demonstrate that eigencells combined with support vector machines produce reasonably high detection accuracy among all the methods.

  20. The nucleoporin ALADIN regulates Aurora A localization to ensure robust mitotic spindle formation

    PubMed Central

    Carvalhal, Sara; Ribeiro, Susana Abreu; Arocena, Miguel; Kasciukovic, Taciana; Temme, Achim; Koehler, Katrin; Huebner, Angela; Griffis, Eric R.

    2015-01-01

    The formation of the mitotic spindle is a complex process that requires massive cellular reorganization. Regulation by mitotic kinases controls this entire process. One of these mitotic controllers is Aurora A kinase, which is itself highly regulated. In this study, we show that the nuclear pore protein ALADIN is a novel spatial regulator of Aurora A. Without ALADIN, Aurora A spreads from centrosomes onto spindle microtubules, which affects the distribution of a subset of microtubule regulators and slows spindle assembly and chromosome alignment. ALADIN interacts with inactive Aurora A and is recruited to the spindle pole after Aurora A inhibition. Of interest, mutations in ALADIN cause triple A syndrome. We find that some of the mitotic phenotypes that we observe after ALADIN depletion also occur in cells from triple A syndrome patients, which raises the possibility that mitotic errors may underlie part of the etiology of this syndrome. PMID:26246606

  1. The STARD9/Kif16a kinesin associates with mitotic microtubules and regulates spindle pole assembly.

    PubMed

    Torres, Jorge Z; Summers, Matthew K; Peterson, David; Brauer, Matthew J; Lee, James; Senese, Silvia; Gholkar, Ankur A; Lo, Yu-Chen; Lei, Xingye; Jung, Kenneth; Anderson, David C; Davis, David P; Belmont, Lisa; Jackson, Peter K

    2011-12-01

    During cell division, cells form the microtubule-based mitotic spindle, a highly specialized and dynamic structure that mediates proper chromosome transmission to daughter cells. Cancer cells can show perturbed mitotic spindles and an approach in cancer treatment has been to trigger cell killing by targeting microtubule dynamics or spindle assembly. To identify and characterize proteins necessary for spindle assembly, and potential antimitotic targets, we performed a proteomic and genetic analysis of 592 mitotic microtubule copurifying proteins (MMCPs). Screening for regulators that affect both mitosis and apoptosis, we report the identification and characterization of STARD9, a kinesin-3 family member, which localizes to centrosomes and stabilizes the pericentriolar material (PCM). STARD9-depleted cells have fragmented PCM, form multipolar spindles, activate the spindle assembly checkpoint (SAC), arrest in mitosis, and undergo apoptosis. Interestingly, STARD9-depletion synergizes with the chemotherapeutic agent taxol to increase mitotic death, demonstrating that STARD9 is a mitotic kinesin and a potential antimitotic target.

  2. 78 FR 25577 - Safety Zone, Figure Eight Causeway Channel; Figure Eight Island, NC

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-02

    ... Security FR Federal Register NPRM Notice of Proposed Rulemaking A. Regulatory History and Information The... Island, NC AGENCY: Coast Guard, DHS. ACTION: Temporary final rule. SUMMARY: The Coast Guard is establishing a safety zone on the navigable waters of Figure Eight Causeway Channel, Figure Eight Island, NC...

  3. 50 CFR Figure 1 to Part 640 - Figure 1 to Part 640

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 8 2010-10-01 2010-10-01 false Figure 1 to Part 640 1 Figure 1 to Part 640 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE SPINY LOBSTER FISHERY OF THE GULF OF MEXICO AND SOUTH ATLANTIC Pt....

  4. 50 CFR Figure 1 to Part 640 - Figure 1 to Part 640

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 12 2012-10-01 2012-10-01 false Figure 1 to Part 640 1 Figure 1 to Part 640 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE SPINY LOBSTER FISHERY OF THE GULF OF MEXICO AND SOUTH ATLANTIC Pt....

  5. 50 CFR Figure 1 to Part 640 - Figure 1 to Part 640

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 10 2011-10-01 2011-10-01 false Figure 1 to Part 640 1 Figure 1 to Part 640 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE SPINY LOBSTER FISHERY OF THE GULF OF MEXICO AND SOUTH ATLANTIC Pt....

  6. Mitotic crossover promotes leukemogenesis in children born with TEL-AML1 via the generation of loss of heterozygosity at 12p.

    PubMed

    Ivanovski, Ivan; Garavelli, Livia; Djurić, Olivera; Ćirović, Aleksandar; Škorić, Dejan; Ivanovski, Petar I

    2015-01-01

    TEL-AML1 (ETV6-RUNX1) fusion gene which is formed prenatally in 1% of the newborns, is a common genetic abnormality in childhood Bcell precursor acute lymphoblastic leukemia. But only one child out of a hundred children born with this fusion gene develops leukemia (bottleneck phenomenon) later in its life, if contracts the second mutation. In other words, out of a hundred children born with TEL-AML1 only one child is at risk for leukemia development, which means that TEL-AML1 fusion gene is not sufficient for overt leukemia. There is a stringent requirement for a second genetic abnormality for leukemia development and this is the real or the ultimate cause of the leukemia bottleneck phenomenon. In most cases of TEL-AML1+ leukemia, the translocation t(12;21) is complemented with the loss of the normal TEL gene, not involved in the translocation, on the contralateral 12p. The loss of the normal TEL gene, i.e. loss of heterozygosity at 12p, occurs postnatally during the mitotic proliferation of TEL-AML1+ cell in the mitotic crossing over process. Mitotic crossing over is a very rare event with a frequency rate of 10-6 in a 10 kb region. The exploration and identification of the environmental exposure(s) that cause(s) proliferation of the TELAML1+ cell in which approximately 106 mitoses are generated to cause 12p loss of heterozygosity, i.e. TEL gene deletion, may contribute to the introduction of preventive measures for leukemia. PMID:26429121

  7. Abnormal human sex chromosome constitutions

    SciTech Connect

    1993-12-31

    Chapter 22, discusses abnormal human sex chromosome constitution. Aneuploidy of X chromosomes with a female phenotype, sex chromosome aneuploidy with a male phenotype, and various abnormalities in X chromosome behavior are described. 31 refs., 2 figs.

  8. Exercises to Improve Gait Abnormalities

    MedlinePlus

    ... Home About iChip Articles Directories Videos Resources Contact Exercises to Improve Gait Abnormalities Home » Article Categories » Exercise and Fitness Font Size: A A A A Exercises to Improve Gait Abnormalities Next Page The manner ...

  9. Abnormal ionization in sonoluminescence

    NASA Astrophysics Data System (ADS)

    Zhang, Wen-Juan; An, Yu

    2015-04-01

    Sonoluminescence is a complex phenomenon, the mechanism of which remains unclear. The present study reveals that an abnormal ionization process is likely to be present in the sonoluminescing bubble. To fit the experimental data of previous studies, we assume that the ionization energies of the molecules and atoms in the bubble decrease as the gas density increases and that the decrease of the ionization energy reaches about 60%-70% as the bubble flashes, which is difficult to explain by using previous models. Project supported by the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20120002110031) and the National Natural Science Foundation of China (Grant No. 11334005).

  10. Noise figure of hybrid optical parametric amplifiers.

    PubMed

    Marhic, Michel E

    2012-12-17

    Following a fiber optical parametric amplifier, used as a wavelength converter or in the phase-sensitive mode, by a phase-insensitive amplifier (PIA) can significantly reduce four-wave mixing between signals in broadband systems. We derive the quantum mechanical noise figures (NF) for these two hybrid configurations, and show that adding the PIA only leads to a moderate increase in NF.

  11. Data Behind the Figures in AAS Journals

    NASA Astrophysics Data System (ADS)

    Biemesderfer, Chris

    2013-01-01

    Substantial amounts of digital data are produced in the scientific enterprise, and much of it is carefully analyzed and processed. Often resulting from a good deal of intellectual effort, many of these highly-processed products are published in the scholarly literature. Many of these data - or more precisely, representations of these data - are committed to the scholarly record in the forms of figures and tables that appear within articles: the AAS journals publish more than 30,000 figures and nearly 10,000 tables each year. For more than a decade, the AAS journals have accepted machine-readable tables that provide the data behind (some of) the tables, and recently the journals have started to encourage the submission of the data behind figures. (See the related poster by Greg Schwarz.) During this time, the journals have been refining techniques for acquiring and managing the digital data that underlie figures and tables. In 2012 the AAS was awarded a grant by the US NSF so that the journals can extend the methods for providing access to these data objects, through a deeper collaboration with the VO and with organizations like DataCite, and by spearheading discussions about the formats and metadata that will best facilitate long-term data management and access. An important component of these activities is educating scientists about the importance and benefits of making such data sets available.

  12. Go Figure. HEADJAM. Teaching Guide [and Videotape].

    ERIC Educational Resources Information Center

    MATHCOUNTS Foundation, Alexandria, VA.

    The HeadJam series is comprised of six programs exploring mathematics, science, and critical thinking skills. It is an award-winning, educational videotape series for middle school students that explores multi-disciplinary skills in a highly entertaining way. The teacher's guide and 22-minute video, "Go Figure," demonstrate how math is used in the…

  13. 36 CFR Appendix - Figures to Part 1194

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Figures to Part 1194 Parks, Forests, and Public Property ARCHITECTURAL AND TRANSPORTATION BARRIERS COMPLIANCE BOARD ELECTRONIC AND INFORMATION TECHNOLOGY ACCESSIBILITY STANDARDS Information, Documentation, and Support...

  14. 36 CFR Appendix - Figures to Part 1192

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 36 Parks, Forests, and Public Property 3 2012-07-01 2012-07-01 false Figures to Part 1192 Parks, Forests, and Public Property ARCHITECTURAL AND TRANSPORTATION BARRIERS COMPLIANCE BOARD AMERICANS WITH DISABILITIES ACT (ADA) ACCESSIBILITY GUIDELINES FOR TRANSPORTATION VEHICLES Other Vehicles and Systems Trams, similar vehicles and systems. Pt....

  15. 36 CFR Appendix - Figures to Part 1194

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 36 Parks, Forests, and Public Property 3 2014-07-01 2014-07-01 false Figures to Part 1194 Parks, Forests, and Public Property ARCHITECTURAL AND TRANSPORTATION BARRIERS COMPLIANCE BOARD ELECTRONIC AND INFORMATION TECHNOLOGY ACCESSIBILITY STANDARDS Information, Documentation, and Support Information, documentation, and support. Pt. 1194,...

  16. 36 CFR Appendix - Figures to Part 1192

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 36 Parks, Forests, and Public Property 3 2013-07-01 2012-07-01 true Figures to Part 1192 Parks, Forests, and Public Property ARCHITECTURAL AND TRANSPORTATION BARRIERS COMPLIANCE BOARD AMERICANS WITH DISABILITIES ACT (ADA) ACCESSIBILITY GUIDELINES FOR TRANSPORTATION VEHICLES Other Vehicles and Systems Trams, similar vehicles and systems. Pt....

  17. 36 CFR Appendix - Figures to Part 1194

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 36 Parks, Forests, and Public Property 3 2013-07-01 2012-07-01 true Figures to Part 1194 Parks, Forests, and Public Property ARCHITECTURAL AND TRANSPORTATION BARRIERS COMPLIANCE BOARD ELECTRONIC AND INFORMATION TECHNOLOGY ACCESSIBILITY STANDARDS Information, Documentation, and Support Information, documentation, and support. Pt. 1194,...

  18. 36 CFR Appendix - Figures to Part 1194

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 36 Parks, Forests, and Public Property 3 2012-07-01 2012-07-01 false Figures to Part 1194 Parks, Forests, and Public Property ARCHITECTURAL AND TRANSPORTATION BARRIERS COMPLIANCE BOARD ELECTRONIC AND INFORMATION TECHNOLOGY ACCESSIBILITY STANDARDS Information, Documentation, and Support Information, documentation, and support. Pt. 1194,...

  19. 36 CFR Appendix - Figures to Part 1192

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 36 Parks, Forests, and Public Property 3 2014-07-01 2014-07-01 false Figures to Part 1192 Parks, Forests, and Public Property ARCHITECTURAL AND TRANSPORTATION BARRIERS COMPLIANCE BOARD AMERICANS WITH DISABILITIES ACT (ADA) ACCESSIBILITY GUIDELINES FOR TRANSPORTATION VEHICLES Other Vehicles and Systems Trams, similar vehicles and systems. Pt....

  20. Precision segmented reflector figure control system architecture.

    NASA Astrophysics Data System (ADS)

    Mettler, E.; Eldred, D.; Briggs, C.; Kiceniuk, T.; Agronin, M.

    1989-09-01

    This paper describes an advanced technology figure control system for a generic class of large space based segmented reflector telescopes. Major technology and design motivations for selection of sensing, actuation, and mechanism approaches result from the high precision and very low mass and power goals for the reflector system.

  1. 36 CFR Appendix - Figures to Part 1192

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Figures to Part 1192 Parks, Forests, and Public Property ARCHITECTURAL AND TRANSPORTATION BARRIERS COMPLIANCE BOARD AMERICANS WITH DISABILITIES ACT (ADA) ACCESSIBILITY GUIDELINES FOR TRANSPORTATION VEHICLES Other Vehicles and Systems Trams, similar vehicles and systems. Pt....

  2. 36 CFR Appendix - Figures to Part 1192

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 36 Parks, Forests, and Public Property 3 2011-07-01 2011-07-01 false Figures to Part 1192 Parks, Forests, and Public Property ARCHITECTURAL AND TRANSPORTATION BARRIERS COMPLIANCE BOARD AMERICANS WITH DISABILITIES ACT (ADA) ACCESSIBILITY GUIDELINES FOR TRANSPORTATION VEHICLES Other Vehicles and Systems Trams, similar vehicles and systems. Pt....

  3. 36 CFR Appendix - Figures to Part 1194

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 36 Parks, Forests, and Public Property 3 2011-07-01 2011-07-01 false Figures to Part 1194 Parks, Forests, and Public Property ARCHITECTURAL AND TRANSPORTATION BARRIERS COMPLIANCE BOARD ELECTRONIC AND INFORMATION TECHNOLOGY ACCESSIBILITY STANDARDS Information, Documentation, and Support Information, documentation, and support. Pt. 1194,...

  4. Adolescent Girls' Parasocial Interactions with Media Figures

    ERIC Educational Resources Information Center

    Theran, Sally A.; Newberg, Emily M.; Gleason, Tracy R.

    2010-01-01

    We examined aspects of adolescent girls' parasocial interactions in the context of typical development. Parasocial interactions are defined as symbolic, one-sided quasi-interactions between a viewer and a media figure. In total, 107 adolescent girls were examined; 94% reported engaging in parasocial interactions to some degree. Preoccupied…

  5. Participation in the Figured World of Graffiti

    ERIC Educational Resources Information Center

    Valle, Imuris; Weiss, Eduardo

    2010-01-01

    This article is based on ethnographic work with two "crews" of young graffiti artists in southern Mexico City. The crews share certain characteristics with gangs or urban tribes, but more with "communities of practice": they live in the "figured world" of graffiti, a community of practice at the local and global level. Through participation,…

  6. T'ang Dynasty Tomb Figure.

    ERIC Educational Resources Information Center

    Selle, Penny

    1988-01-01

    Uses a print of a T'ang Dynasty tomb figure to acquaint grades 10-12 students with the tools needed for developing aesthetic judgement and artistic criticism. Includes background on the artwork and instructional strategies to help students describe the object, analyze the artmaking process, and formulate their own opinions. (GEA)

  7. Teaching Significant Figures Using Age Conversions

    ERIC Educational Resources Information Center

    Crute, Thomas D.

    2005-01-01

    Some useful approaches to assist students with the uncertainty of measurement and the necessity of significant figures through age conversion exercise and activity are presented. It showed that while two people might be born on the same date, they are not born at the same instant once, it considers the birth time to an appropriate number of…

  8. Facts & Figures about Education in Alaska, 1992.

    ERIC Educational Resources Information Center

    Alaska State Dept. of Education, Juneau.

    This collection of tables presents selected facts and figures about education in Alaska. General and district school information about Alaska's 469 public schools in 54 districts and its 276 private and denominational schools is followed by tables of general student information, including average daily membership, enrollment, graduates, and…

  9. The Offerings of Fringe Figures and Migrants

    ERIC Educational Resources Information Center

    Engels-Schwarzpaul, A.-Chr.

    2015-01-01

    "The Western tradition", as passe-partout, includes fringe figures, émigrés and migrants. Rather than looking to resources at the core of the Western tradition to overcome its own blindnesses, I am more interested in its gaps and peripheries, where other thoughts and renegade knowledges take hold. It is in the contact zones with…

  10. Asymmetric spindle pole formation in CPAP-depleted mitotic cells.

    PubMed

    Lee, Miseon; Chang, Jaerak; Chang, Sunghoe; Lee, Kyung S; Rhee, Kunsoo

    2014-02-21

    CPAP is an essential component for centriole formation. Here, we report that CPAP is also critical for symmetric spindle pole formation during mitosis. We observed that pericentriolar material between the mitotic spindle poles were asymmetrically distributed in CPAP-depleted cells even with intact numbers of centrioles. The length of procentrioles was slightly reduced by CPAP depletion, but the length of mother centrioles was not affected. Surprisingly, the young mother centrioles of the CPAP-depleted cells are not fully matured, as evidenced by the absence of distal and subdistal appendage proteins. We propose that the selective absence of centriolar appendages at the young mother centrioles may be responsible for asymmetric spindle pole formation in CPAP-depleted cells. Our results suggest that the neural stem cells with CPAP mutations might form asymmetric spindle poles, which results in premature initiation of differentiation.

  11. Chondroblastoma of the temporal base with high mitotic activity.

    PubMed

    Ishikawa, Eiichi; Tsuboi, Koji; Onizawa, Kojiro; Hara, Akira; Kusakari, Jun; Noguchi, Masayuki; Nose, Tadao

    2002-11-01

    A 24-year-old man presented with a rare chondroblastoma of the temporal base manifesting as local pain accompanied by difficulty in opening the mouth. Gross total removal was achieved at initial surgery, but the tumor demonstrated rapid and destructive regrowth from a very small residual volume without definite histological malignant transformation. Growth activity estimated by MIB-1 staining increased spontaneously from 2.5% at the initial operation to 18.7% at recurrence. Further extensive radical tumor removal by surgeons from multiple disciplines was performed. The patient has been free of recurrence for 3 years without radiotherapy. Chondroblastoma of the temporal bone is widely accepted as a benign tumor and regrowth after gross total removal is very rare. However, some cases of chondroblastoma have potentially high mitotic activity.

  12. Chondroblastoma of the temporal base with high mitotic activity.

    PubMed

    Ishikawa, Eiichi; Tsuboi, Koji; Onizawa, Kojiro; Hara, Akira; Kusakari, Jun; Noguchi, Masayuki; Nose, Tadao

    2002-11-01

    A 24-year-old man presented with a rare chondroblastoma of the temporal base manifesting as local pain accompanied by difficulty in opening the mouth. Gross total removal was achieved at initial surgery, but the tumor demonstrated rapid and destructive regrowth from a very small residual volume without definite histological malignant transformation. Growth activity estimated by MIB-1 staining increased spontaneously from 2.5% at the initial operation to 18.7% at recurrence. Further extensive radical tumor removal by surgeons from multiple disciplines was performed. The patient has been free of recurrence for 3 years without radiotherapy. Chondroblastoma of the temporal bone is widely accepted as a benign tumor and regrowth after gross total removal is very rare. However, some cases of chondroblastoma have potentially high mitotic activity. PMID:12472218

  13. Substrate length requirements for efficient mitotic recombination in Saccharomyces cerevisiae.

    PubMed Central

    Jinks-Robertson, S; Michelitch, M; Ramcharan, S

    1993-01-01

    An ectopic recombination system using ura3 heteroalleles varying in size from 80 to 960 bp has been used to examine the effect of substrate length on spontaneous mitotic recombination. The ura3 heteroalleles were positioned either on nonhomologous chromosomes (heterochromosomal repeats) or as direct or inverted repeats on the same chromosome (intrachromosomal repeats). While the intrachromosomal events occur at rates at least 2 orders of magnitude greater than the corresponding heterochromosomal events, the recombination rate for each type of repeat considered separately exhibits a linear dependence on substrate length. The linear relationships allow estimation of the corresponding minimal efficient processing segments, which are approximately 250 bp regardless of the relative positions of the repeats in the yeast genome. An examination of the distribution of recombination events into simple gene conversion versus crossover events indicates that reciprocal exchange is more sensitive to substrate size than is gene conversion. PMID:8321201

  14. Mitotic Exit and Separation of Mother and Daughter Cells

    PubMed Central

    Weiss, Eric L.

    2012-01-01

    Productive cell proliferation involves efficient and accurate splitting of the dividing cell into two separate entities. This orderly process reflects coordination of diverse cytological events by regulatory systems that drive the cell from mitosis into G1. In the budding yeast Saccharomyces cerevisiae, separation of mother and daughter cells involves coordinated actomyosin ring contraction and septum synthesis, followed by septum destruction. These events occur in precise and rapid sequence once chromosomes are segregated and are linked with spindle organization and mitotic progress by intricate cell cycle control machinery. Additionally, critical parts of the mother/daughter separation process are asymmetric, reflecting a form of fate specification that occurs in every cell division. This chapter describes central events of budding yeast cell separation, as well as the control pathways that integrate them and link them with the cell cycle. PMID:23212898

  15. Aurora A's Functions During Mitotic Exit: The Guess Who Game.

    PubMed

    Reboutier, David; Benaud, Christelle; Prigent, Claude

    2015-01-01

    Until recently, the knowledge of Aurora A kinase functions during mitosis was limited to pre-metaphase events, particularly centrosome maturation, G2/M transition, and mitotic spindle assembly. However, an involvement of Aurora A in post-metaphase events was also suspected, but not clearly demonstrated due to the technical difficulty to perform the appropriate experiments. Recent developments of both an analog-specific version of Aurora A and small molecule inhibitors have led to the first demonstration that Aurora A is required for the early steps of cytokinesis. As in pre-metaphase, Aurora A plays diverse functions during anaphase, essentially participating in astral microtubules dynamics and central spindle assembly and functioning. The present review describes the experimental systems used to decipher new functions of Aurora A during late mitosis and situate these functions into the context of cytokinesis mechanisms. PMID:26734572

  16. Mitotic wavefronts mediated by mechanical signaling in early Drosophila embryos

    NASA Astrophysics Data System (ADS)

    Kang, Louis; Idema, Timon; Liu, Andrea; Lubensky, Tom

    2013-03-01

    Mitosis in the early Drosophila embryo demonstrates spatial and temporal correlations in the form of wavefronts that travel across the embryo in each cell cycle. This coordinated phenomenon requires a signaling mechanism, which we suggest is mechanical in origin. We have constructed a theoretical model that supports nonlinear wavefront propagation in a mechanically-excitable medium. Previously, we have shown that this model captures quantitatively the wavefront speed as it varies with cell cycle number, for reasonable values of the elastic moduli and damping coefficient of the medium. Now we show that our model also captures the displacements of cell nuclei in the embryo in response to the traveling wavefront. This new result further supports that mechanical signaling may play an important role in mediating mitotic wavefronts.

  17. Abnormal hematological indices in cirrhosis

    PubMed Central

    Qamar, Amir A; Grace, Norman D

    2009-01-01

    Abnormalities in hematological indices are frequently encountered in cirrhosis. Multiple causes contribute to the occurrence of hematological abnormalities. Recent studies suggest that the presence of hematological cytopenias is associated with a poor prognosis in cirrhosis. The present article reviews the pathogenesis, incidence, prevalence, clinical significance and treatment of abnormal hematological indices in cirrhosis. PMID:19543577

  18. Induction of mitotic and chromosomal abnormalities on Allium cepa cells by pesticides imidacloprid and sulfentrazone and the mixture of them.

    PubMed

    Bianchi, Jaqueline; Fernandes, Thais Cristina Casimiro; Marin-Morales, Maria Aparecida

    2016-02-01

    To evaluate the cytotoxic and genotoxic effects of low concentrations of pesticides in non-target organisms, seeds of Allium cepa were exposed for 24 h to the imidacloprid insecticide, sulfentrazone herbicide and to the mixture of them, followed by recovery periods of 48 and 72 h. Imidacloprid results indicated an indirect genotoxic effect by inducing different types of chromosome aberration (CA), mainly bridges and chromosomal adherences. Cells with micronucleus (MN) were not significant in the analyzed meristems. Moreover, the 72-h recovery tests indicated that the two lower concentrations of the insecticide (0.036 and 0.36 g L(-1)) had their genotoxic effects minimized after discontinuation of treatment, differently to the observed for the field concentration (3.6 g L(-1)). Sulfentrazone herbicide at field concentration (6 g L(-1)) caused cytotoxic effects by inducing nuclear fragmentation and inhibition of cell division. The other concentrations (0.06, 0.6 and 1.2 g L(-1)) indicated genotoxic effects for this herbicide. The concentration of 0.06 g L(-1) induced persistent effects that could be visualized both by the induction of CA in the recovery times as by the presence of MN in meristematic and F1 cells. The induction of MN by this lowest concentration was associated with the great amount of breakage, losses and chromosomal bridges. The mixture of pesticides induced genotoxic and cytotoxic effects, by reducing the MI of the cells. The chromosomal damage induced by the mixture of pesticides was not persistent to the cells, since such damage was minimized 72 h after the interruption of the exposure. PMID:26386773

  19. Induction of mitotic and chromosomal abnormalities on Allium cepa cells by pesticides imidacloprid and sulfentrazone and the mixture of them.

    PubMed

    Bianchi, Jaqueline; Fernandes, Thais Cristina Casimiro; Marin-Morales, Maria Aparecida

    2016-02-01

    To evaluate the cytotoxic and genotoxic effects of low concentrations of pesticides in non-target organisms, seeds of Allium cepa were exposed for 24 h to the imidacloprid insecticide, sulfentrazone herbicide and to the mixture of them, followed by recovery periods of 48 and 72 h. Imidacloprid results indicated an indirect genotoxic effect by inducing different types of chromosome aberration (CA), mainly bridges and chromosomal adherences. Cells with micronucleus (MN) were not significant in the analyzed meristems. Moreover, the 72-h recovery tests indicated that the two lower concentrations of the insecticide (0.036 and 0.36 g L(-1)) had their genotoxic effects minimized after discontinuation of treatment, differently to the observed for the field concentration (3.6 g L(-1)). Sulfentrazone herbicide at field concentration (6 g L(-1)) caused cytotoxic effects by inducing nuclear fragmentation and inhibition of cell division. The other concentrations (0.06, 0.6 and 1.2 g L(-1)) indicated genotoxic effects for this herbicide. The concentration of 0.06 g L(-1) induced persistent effects that could be visualized both by the induction of CA in the recovery times as by the presence of MN in meristematic and F1 cells. The induction of MN by this lowest concentration was associated with the great amount of breakage, losses and chromosomal bridges. The mixture of pesticides induced genotoxic and cytotoxic effects, by reducing the MI of the cells. The chromosomal damage induced by the mixture of pesticides was not persistent to the cells, since such damage was minimized 72 h after the interruption of the exposure.

  20. Spirometric abnormalities among welders

    SciTech Connect

    Rastogi, S.K.; Gupta, B.N.; Husain, T.; Mathur, N.; Srivastava, S. )

    1991-10-01

    A group of manual welders age group 13-60 years having a mean exposure period of 12.4 {plus minus} 1.12 years were subjected to spirometry to evaluate the prevalence of spirometric abnormalities. The welders showed a significantly higher prevalence of respiratory impairment than that observed among the unexposed controls as a result of exposure to welding gases which comprised fine particles of lead, zinc, chromium, and manganese. This occurred despite the lower concentration of the pollutants at the work place. In the expose group, the smoking welders showed a prevalence of respiratory impairment significantly higher than that observed in the nonsmoking welders. The results of the pulmonary function tests showed a predominantly restrictive type of pulmonary impairment followed by a mixed ventilatory defect among the welders. The effect of age on pulmonary impairment was not discernible. Welders exposed for over 10 years showed a prevalence of respiratory abnormalities significantly higher than those exposed for less than 10 years. Smoking also had a contributory role.

  1. Closed MAD2 (C-MAD2) is selectively incorporated into the mitotic checkpoint complex (MCC)

    PubMed Central

    Tipton, Aaron R; Tipton, Michael; Yen, Tim

    2011-01-01

    The mitotic checkpoint is a specialized signal transduction pathway that monitors kinetochore-microtubule attachment to achieve faithful chromosome segregation. MAD2 is an evolutionarily conserved mitotic checkpoint protein that exists in open (O) and closed (C) conformations. The increase of intracellular C-MAD2 level during mitosis, through O→C-MAD2 conversion as catalyzed by unattached kinetochores, is a critical signaling event for the mitotic checkpoint. However, it remains controversial whether MAD2 is an integral component of the effector of the mitotic checkpoint—the mitotic checkpoint complex (MCC). We show here that endogenous human MCC is assembled by first forming a BUBR1:BUB3:CDC20 complex in G2 and then selectively incorporating C-MAD2 during mitosis. Nevertheless, MCC can be induced to form in G1/S cells by expressing a C-conformation locked MAD2 mutant, indicating intracellular level of C-MAD2 as a major limiting factor for MCC assembly. In addition, a recombinant MCC containing C-MAD2 exhibits effective inhibitory activity toward APC/C isolated from mitotic HeLa cells, while a recombinant BUBR1:BUB3:CDC20 ternary complex is ineffective at comparable concentrations despite association with APC/C. These results help establish a direct connection between a major signal transducer (C-MAD2) and the potent effector (MCC) of the mitotic checkpoint, and provide novel insights into protein-protein interactions during assembly of a functional MCC. PMID:22037211

  2. Efficient Activation of Apoptotic Signaling during Mitotic Arrest with AK301

    PubMed Central

    Bleiler, Marina; Yeagley, Michelle; Wright, Dennis; Giardina, Charles

    2016-01-01

    Mitotic inhibitors are widely utilized chemotherapeutic agents that take advantage of mitotic defects in cancer cells. We have identified a novel class of piperazine-based mitotic inhibitors, of which AK301 is the most potent derivative identified to date (EC50 < 200 nM). Colon cancer cells arrested in mitosis with AK301 readily underwent a p53-dependent apoptosis following compound withdrawal and arrest release. This apoptotic response was significantly higher for AK301 than for other mitotic inhibitors tested (colchicine, vincristine, and BI 2536). AK301-treated cells exhibited a robust mitosis-associated DNA damage response, including ATM activation, γH2AX phosphorylation and p53 stabilization. The association between mitotic signaling and the DNA damage response was supported by the finding that Aurora B inhibition reduced the level of γH2AX staining. Confocal imaging of AK301-treated cells revealed multiple γ-tubulin microtubule organizing centers attached to microtubules, but with limited centrosome migration, raising the possibility that aberrant microtubule pulling may underlie DNA breakage. AK301 selectively targeted APC-mutant colonocytes and promoted TNF-induced apoptosis in p53-mutant colon cancer cells. Our findings indicate that AK301 induces a mitotic arrest state with a highly active DNA damage response. Together with a reversible arrest state, AK301 is a potent promoter of a mitosis-to-apoptosis transition that can target cancer cells with mitotic defects. PMID:27097159

  3. Irreversibility of mitotic exit is the consequence of systems level feedback

    PubMed Central

    López-Avilés, Sandra; Kapuy, Orsolya; Novák, Béla; Uhlmann, Frank

    2009-01-01

    The eukaryotic cell cycle comprises an ordered series of events, orchestrated by the activity of cyclin-dependent kinases (Cdks), leading from chromosome replication during S-phase to their segregation in mitosis. The unidirectionality of cell cycle transitions is fundamental for successful completion of this cycle. It is thought that irrevocable proteolytic degradation of key cell cycle regulators makes cell cycle transitions irreversible, thereby enforcing directionality1-3. Here, we have experimentally examined the contribution of cyclin proteolysis to the irreversibility of mitotic exit, the transition from high mitotic Cdk activity back to low activity in G1. We show that forced cyclin destruction in mitotic budding yeast cells efficiently drives mitotic exit events. However, these remain reversible after termination of cyclin proteolysis, with recovery of the mitotic state and cyclin levels. Mitotic exit becomes irreversible only after longer periods of cyclin degradation, due to activation of a double-negative feedback loop involving the Cdk inhibitor Sic1 (refs 4​,​5). Quantitative modelling suggests that feedback is required to maintain low Cdk activity and to prevent cyclin resynthesis. Our findings demonstrate that unidirectionality of mitotic exit is not the consequence of proteolysis but of systems level feedback required to maintain the cell cycle in a new stable state. PMID:19387440

  4. AMPK and PFKFB3 mediate glycolysis and survival in response to mitophagy during mitotic arrest.

    PubMed

    Doménech, Elena; Maestre, Carolina; Esteban-Martínez, Lorena; Partida, David; Pascual, Rosa; Fernández-Miranda, Gonzalo; Seco, Esther; Campos-Olivas, Ramón; Pérez, Manuel; Megias, Diego; Allen, Katherine; López, Miguel; Saha, Asish K; Velasco, Guillermo; Rial, Eduardo; Méndez, Raúl; Boya, Patricia; Salazar-Roa, María; Malumbres, Marcos

    2015-10-01

    Blocking mitotic progression has been proposed as an attractive therapeutic strategy to impair proliferation of tumour cells. However, how cells survive during prolonged mitotic arrest is not well understood. We show here that survival during mitotic arrest is affected by the special energetic requirements of mitotic cells. Prolonged mitotic arrest results in mitophagy-dependent loss of mitochondria, accompanied by reduced ATP levels and the activation of AMPK. Oxidative respiration is replaced by glycolysis owing to AMPK-dependent phosphorylation of PFKFB3 and increased production of this protein as a consequence of mitotic-specific translational activation of its mRNA. Induction of autophagy or inhibition of AMPK or PFKFB3 results in enhanced cell death in mitosis and improves the anti-tumoral efficiency of microtubule poisons in breast cancer cells. Thus, survival of mitotic-arrested cells is limited by their metabolic requirements, a feature with potential implications in cancer therapies aimed to impair mitosis or metabolism in tumour cells.

  5. Determinants of mitotic catastrophe on abrogation of the G2 DNA damage checkpoint by UCN-01.

    PubMed

    On, Kin Fan; Chen, Yue; Ma, Hoi Tang; Chow, Jeremy P H; Poon, Randy Y C

    2011-05-01

    Genotoxic stress such as ionizing radiation halts entry into mitosis by activation of the G(2) DNA damage checkpoint. The CHK1 inhibitor 7-hydroxystaurosporine (UCN-01) can bypass the checkpoint and induce unscheduled mitosis in irradiated cells. Precisely, how cells behave following checkpoint abrogation remains to be defined. In this study, we tracked the fates of individual cells after checkpoint abrogation, focusing in particular on whether they undergo mitotic catastrophe. Surprisingly, while a subset of UCN-01-treated cells were immediately eliminated during the first mitosis after checkpoint abrogation, about half remained viable and progressed into G(1). Both the delay of mitotic entry and the level of mitotic catastrophe were dependent on the dose of radiation. Although the level of mitotic catastrophe was specific for different cell lines, it could be promoted by extending the mitosis. In supporting this idea, weakening of the spindle-assembly checkpoint, by either depleting MAD2 or overexpressing the MAD2-binding protein p31(comet), suppressed mitotic catastrophe. Conversely, delaying of mitotic exit by depleting either p31(comet) or CDC20 tipped the balance toward mitotic catastrophe. These results underscore the interplay between the level of DNA damage and the effectiveness of the spindle-assembly checkpoint in determining whether checkpoint-abrogated cells are eliminated during mitosis.

  6. Investigating the regulation of stem and progenitor cell mitotic progression by in situ imaging.

    PubMed

    Gerhold, Abigail R; Ryan, Joël; Vallée-Trudeau, Julie-Nathalie; Dorn, Jonas F; Labbé, Jean-Claude; Maddox, Paul S

    2015-05-01

    Genome stability relies upon efficacious chromosome congression and regulation by the spindle assembly checkpoint (SAC). The study of these fundamental mitotic processes in adult stem and progenitor cells has been limited by the technical challenge of imaging mitosis in these cells in situ. Notably, how broader physiological changes, such as dietary intake or age, affect mitotic progression in stem and/or progenitor cells is largely unknown. Using in situ imaging of C. elegans adult germlines, we describe the mitotic parameters of an adult stem and progenitor cell population in an intact animal. We find that SAC regulation in germline stem and progenitor cells is distinct from that found in early embryonic divisions and is more similar to that of classical tissue culture models. We further show that changes in organismal physiology affect mitotic progression in germline stem and progenitor cells. Reducing dietary intake produces a checkpoint-dependent delay in anaphase onset, and inducing dietary restriction when the checkpoint is impaired increases the incidence of segregation errors in mitotic and meiotic cells. Similarly, developmental aging of the germline stem and progenitor cell population correlates with a decline in the rate of several mitotic processes. These results provide the first in vivo validation of models for SAC regulation developed in tissue culture systems and demonstrate that several fundamental features of mitotic progression in adult stem and progenitor cells are highly sensitive to organismal physiological changes.

  7. A Rare Stapes Abnormality

    PubMed Central

    Kanona, Hala; Virk, Jagdeep Singh; Kumar, Gaurav; Chawda, Sanjiv; Khalil, Sherif

    2015-01-01

    The aim of this study is to increase awareness of rare presentations, diagnostic difficulties alongside management of conductive hearing loss and ossicular abnormalities. We report the case of a 13-year-old female reporting progressive left-sided hearing loss and high resolution computed tomography was initially reported as normal. Exploratory tympanotomy revealed an absent stapedius tendon and lack of connection between the stapes superstructure and footplate. The footplate was fixed. Stapedotomy and stapes prosthesis insertion resulted in closure of the air-bone gap by 50 dB. A review of world literature was performed using MedLine. Middle ear ossicular discontinuity can result in significant conductive hearing loss. This can be managed effectively with surgery to help restore hearing. However, some patients may not be suitable or decline surgical intervention and can be managed safely conservatively. PMID:25628909

  8. Species-specific heterochromatin prevents mitotic chromosome segregation to cause hybrid lethality in Drosophila.

    PubMed

    Ferree, Patrick M; Barbash, Daniel A

    2009-10-01

    Postzygotic reproductive barriers such as sterility and lethality of hybrids are important for establishing and maintaining reproductive isolation between species. Identifying the causal loci and discerning how they interfere with the development of hybrids is essential for understanding how hybrid incompatibilities (HIs) evolve, but little is known about the mechanisms of how HI genes cause hybrid dysfunctions. A previously discovered Drosophila melanogaster locus called Zhr causes lethality in F1 daughters from crosses between Drosophila simulans females and D. melanogaster males. Zhr maps to a heterochromatic region of the D. melanogaster X that contains 359-bp satellite repeats, suggesting either that Zhr is a rare protein-coding gene embedded within heterochromatin, or is a locus consisting of the noncoding repetitive DNA that forms heterochromatin. The latter possibility raises the question of how heterochromatic DNA can induce lethality in hybrids. Here we show that hybrid females die because of widespread mitotic defects induced by lagging chromatin at the time during early embryogenesis when heterochromatin is first established. The lagging chromatin is confined solely to the paternally inherited D. melanogaster X chromatids, and consists predominantly of DNA from the 359-bp satellite block. We further found that a rearranged X chromosome carrying a deletion of the entire 359-bp satellite block segregated normally, while a translocation of the 359-bp satellite block to the Y chromosome resulted in defective Y segregation in males, strongly suggesting that the 359-bp satellite block specifically and directly inhibits chromatid separation. In hybrids produced from wild-type parents, the 359-bp satellite block was highly stretched and abnormally enriched with Topoisomerase II throughout mitosis. The 359-bp satellite block is not present in D. simulans, suggesting that lethality is caused by the absence or divergence of factors in the D. simulans maternal

  9. Mitotic Intragenic Recombination: A Mechanism of Survival for Several Congenital Disorders of Glycosylation

    PubMed Central

    Kane, Megan S.; Davids, Mariska; Adams, Christopher; Wolfe, Lynne A.; Cheung, Helen W.; Gropman, Andrea; Huang, Yan; Ng, Bobby G.; Freeze, Hudson H.; Adams, David R.; Gahl, William A.; Boerkoel, Cornelius F.

    2016-01-01

    Congenital disorders of glycosylation (CDGs) are disorders of abnormal protein glycosylation that affect multiple organ systems. Because most CDGs have been described in only a few individuals, our understanding of the associated phenotypes and the mechanisms of individual survival are limited. In the process of studying two siblings, aged 6 and 11 years, with MOGS-CDG and biallelic MOGS (mannosyl-oligosaccharide glucosidase) mutations (GenBank: NM_006302.2; c.[65C>A; 329G>A] p.[Ala22Glu; Arg110His]; c.[370C>T] p.[Gln124∗]), we noted that their survival was much longer than the previous report of MOGS-CDG, in a child who died at 74 days of age. Upon mutation analysis, we detected multiple MOGS genotypes including wild-type alleles in their cultured fibroblast and peripheral blood DNA. Further analysis of DNA from cultured fibroblasts of six individuals with compound heterozygous mutations of PMM2 (PMM2-CDG), MPI (MPI-CDG), ALG3 (ALG3-CDG), ALG12 (ALG12-CDG), DPAGT1 (DPAGT1-CDG), and ALG1 (ALG1-CDG) also identified multiple genotypes including wild-type alleles for each. Droplet digital PCR showed a ratio of nearly 1:1 wild-type to mutant alleles for most, but not all, mutations. This suggests that mitotic recombination contributes to the survival and the variable expressivity of individuals with compound heterozygous CDGs. This also provides an explanation for prior observations of a reduced frequency of homozygous mutations and might contribute to increased levels of residual enzyme activity in cultured fibroblasts of individuals with MPI- and PMM2-CDGs. PMID:26805780

  10. Figure correction of multilayer coated optics

    DOEpatents

    Chapman; Henry N. , Taylor; John S.

    2010-02-16

    A process is provided for producing near-perfect optical surfaces, for EUV and soft-x-ray optics. The method involves polishing or otherwise figuring the multilayer coating that has been deposited on an optical substrate, in order to correct for errors in the figure of the substrate and coating. A method such as ion-beam milling is used to remove material from the multilayer coating by an amount that varies in a specified way across the substrate. The phase of the EUV light that is reflected from the multilayer will be affected by the amount of multilayer material removed, but this effect will be reduced by a factor of 1-n as compared with height variations of the substrate, where n is the average refractive index of the multilayer.

  11. Variable-spot ion beam figuring

    NASA Astrophysics Data System (ADS)

    Wu, Lixiang; Qiu, Keqiang; Fu, Shaojun

    2016-03-01

    This paper introduces a new scheme of ion beam figuring (IBF), or rather variable-spot IBF, which is conducted at a constant scanning velocity with variable-spot ion beam collimated by a variable diaphragm. It aims at improving the reachability and adaptation of the figuring process within the limits of machine dynamics by varying the ion beam spot size instead of the scanning velocity. In contrast to the dwell time algorithm in the conventional IBF, the variable-spot IBF adopts a new algorithm, which consists of the scan path programming and the trajectory optimization using pattern search. In this algorithm, instead of the dwell time, a new concept, integral etching time, is proposed to interpret the process of variable-spot IBF. We conducted simulations to verify its feasibility and practicality. The simulation results indicate the variable-spot IBF is a promising alternative to the conventional approach.

  12. Cassini State Transitions with a Fossil Figure

    NASA Astrophysics Data System (ADS)

    Matsuyama, Isamu; Tuttle Keane, James

    2016-10-01

    The Moon has experienced large obliquity variations during Cassini state transitions which greatly impact tidal heating, and the long-term stability of polar volatiles. It has been known for centuries that the lunar rotational and tidal bulges are much larger than expected. The South Pole-Aitken basin can explain a large fraction of the excess deformation. Accounting for the contribution of this basin (and other large basins), the remaining excess deformation arises due to a fossil figure established when the Moon orbited much closer to Earth than it does today. Previous studies assume that the present, excess deformation is entirely preserved throughout Cassini state transitions. This ignores basin contributions to the excess deformation, and requires an interior with infinite rigidity. We consider Cassini state transition models that take into account basin contributions to the excess deformation, and the effect of finite rigidity on the fossil figure.

  13. Recommended Figures of Merit for Green Monopropellants

    NASA Technical Reports Server (NTRS)

    Marshall. William M.; Deans, Matthew C.

    2013-01-01

    Hydrazine propellant has historically been used as a rocket thruster monopropellant since the mid-1960s. Mission managers are well aware of its characteristics and performance. However, it is a known toxic chemical and a wide effort is underway to reduce and/or eliminate its use worldwide. Several new propellant combinations have been developed in the last few years which tout or promise to provide same or better performance as hydrazine while being "non-toxic" or "green". Yet, there is no consistent definition for what constitutes "non-toxic" or "green", and thus no good figure of merit for which to compare. This paper seeks to review the three major categories of figures of merit, and discusses how they might be used to assess the viability of a propellant.

  14. Figure and finish of grazing incidence mirrors

    SciTech Connect

    Takacs, P.Z. ); Church, E.L. . Army Armament Research, Development and Engineering Center)

    1989-08-01

    Great improvement has been made in the past several years in the quality of optical components used in synchrotron radiation (SR) beamlines. Most of this progress has been the result of vastly improved metrology techniques and instrumentation permitting rapid and accurate measurement of the surface finish and figure on grazing incidence optics. A significant theoretical effort has linked the actual performance of components used as x-ray wavelengths to their topological properties as measured by surface profiling instruments. Next-generation advanced light sources will require optical components and systems to have sub-arc second surface figure tolerances. This paper will explore the consequences of these requirements in terms of manufacturing tolerances to see if the present manufacturing state-of-the-art is capable of producing the required surfaces. 15 refs., 14 figs., 2 tabs.

  15. [The endemic goitre in figurative arts].

    PubMed

    Giampalmo, A

    1996-01-01

    For the past fifteen years the author has been collecting photografic documentation of works of figurative arts (graffiti, mosiac, engravings, paintings and sculptures) made at different times and places, in which he found mostly unintentional display of diseases or deformities that would be clearly identified in nosography in the light of today's knowledge. In this study the author intends to illustrate briefly different cases on endemic goitre - whose representation is particularly frequent in figurative arts - in chronological order, beginning with the most ancient ones and focussing on Italian portraying of the Nativity and the Passion of Christ, where the most striking infirmities and disabilities were mirrored and commonly accepted. This study whose interest lies between a scientific and a humanistic one has also importance in the field of art, and especially in relevant philological research which is of particular importance to us pathologists. At last it contribute to establish the epidemiology of some diseases and the knowledge of historical and geographical pathology.

  16. Mitotic and Meiotic Gene Conversion of Ty Elements and Other Insertions in Saccharomyces Cerevisiae

    PubMed Central

    Vincent, A.; Petes, T. D.

    1989-01-01

    We examined meiotic and mitotic gene conversion events involved in deletion of Ty elements and other insertions from the genome of the yeast Saccharomyces cerevisiae. We found that Ty elements and one other insertion were deleted by mitotic gene conversion less frequently than point mutations at the same loci. One non-Ty insertion similar in size to Ty, however, did not show this bias. Mitotic conversion events deleting insertions were more frequently associated with crossing over than those deleting point mutations. In meiosis, conversion events duplicating the element were more common than those that deleted the element for one of the loci (HIS4) examined. PMID:2547693

  17. Mitotic spindle assembly on chromatin patterns made with deep UV photochemistry.

    PubMed

    Tarnawska, Katarzyna; Pugieux, Céline; Nédélec, François

    2014-01-01

    We provide a detailed method to generate arrays of mitotic spindles in vitro. Spindles are formed in extract prepared from unfertilized Xenopus laevis eggs, which contain all the molecular ingredients of mitotic spindles. The method is based on using deep UV photochemistry to attach chromatin-coated beads on a glass surface according to a pattern of interest. The immobilized beads act as artificial chromosomes, and induce the formation of mitotic spindles in their immediate vicinity. To perform the experiment, a chamber is assembled over the chromatin pattern, Xenopus egg extract is flowed in and after incubation the spindles are imaged with a confocal microscope. PMID:24484654

  18. Mitotic spindle assembly on chromatin patterns made with deep UV photochemistry.

    PubMed

    Tarnawska, Katarzyna; Pugieux, Céline; Nédélec, François

    2014-01-01

    We provide a detailed method to generate arrays of mitotic spindles in vitro. Spindles are formed in extract prepared from unfertilized Xenopus laevis eggs, which contain all the molecular ingredients of mitotic spindles. The method is based on using deep UV photochemistry to attach chromatin-coated beads on a glass surface according to a pattern of interest. The immobilized beads act as artificial chromosomes, and induce the formation of mitotic spindles in their immediate vicinity. To perform the experiment, a chamber is assembled over the chromatin pattern, Xenopus egg extract is flowed in and after incubation the spindles are imaged with a confocal microscope.

  19. Early Expressed Clb Proteins Allow Accumulation of Mitotic Cyclin by Inactivating Proteolytic Machinery during S Phase

    PubMed Central

    Yeong, Foong May; Lim, Hong Hwa; Wang, Ya; Surana, Uttam

    2001-01-01

    Periodic accumulation and destruction of mitotic cyclins are important for the initiation and termination of M phase. It is known that both APCCdc20 and APCHct1 collaborate to destroy mitotic cyclins during M phase. Here we show that this relationship between anaphase-promoting complex (APC) and Clb proteins is reversed in S phase such that the early Clb kinases (Clb3, Clb4, and Clb5 kinases) inactivate APCHct1 to allow Clb2 accumulation. This alternating antagonism between APC and Clb proteins during S and M phases constitutes an oscillatory system that generates undulations in the levels of mitotic cyclins. PMID:11438663

  20. Plk1 puts a (Has)pin on the mitotic histone code

    PubMed Central

    Moutinho-Santos, Tatiana; Maiato, Helder

    2014-01-01

    Haspin is an atypical mitotic kinase that phosphorylates histone H3 on threonine 3 (H3T3), which is required to target Aurora B to centromeres. However, how Haspin is activated upon mitotic entry remained unknown. Two independent studies, published in Molecular Cell and in this issue of EMBO reports by Ghenoiu et al [1] and Zhou et al [2], respectively, now show that Plk1 is responsible for Haspin activation as a H3T3 kinase. These results shed light on the spatiotemporal regulation of Aurora B to ensure mitotic fidelity. PMID:24531719

  1. Plk1 puts a (Has)pin on the mitotic histone code.

    PubMed

    Moutinho-Santos, Tatiana; Maiato, Helder

    2014-03-01

    Haspin is an atypical mitotic kinase that phosphorylates histone H3 on threonine 3 (H3T3), which is required to target Aurora B to centromeres. However, how Haspin is activated upon mitotic entry remained unknown. Two independent studies, published in Molecular Cell and in this issue of EMBO reports by Ghenoiu et al and Zhou et al, respectively, now show that Plk1 is responsible for Haspin activation as a H3T3 kinase. These results shed light on the spatiotemporal regulation of Aurora B to ensure mitotic fidelity. PMID:24531719

  2. Atomic Force Microscopy to Study Mechanics of Living Mitotic Mammalian Cells

    NASA Astrophysics Data System (ADS)

    Toyoda, Yusuke; Stewart, Martin P.; Hyman, Anthony A.; Müller, Daniel J.

    2011-08-01

    While biochemical pathways within mitotic cells have been intensively studied, the mechanics of dividing cells is only poorly understood. In our recent report, an experimental system combining fluorescence and atomic force microscopy was set up to study dynamics of mitotic rounding of mammalian cells. We show that cells have a rounding pressure that increases upon mitotic entry. Using specific inhibitors or perturbations, we revealed biological processes required for force generation that underpin the cell rounding shape change during mitosis. The significance of the finding and an outlook are discussed.

  3. Karyotypic abnormalities in tumours of the pancreas.

    PubMed Central

    Bardi, G.; Johansson, B.; Pandis, N.; Mandahl, N.; Bak-Jensen, E.; Andrén-Sandberg, A.; Mitelman, F.; Heim, S.

    1993-01-01

    Short-term cultures from 20 pancreatic tumours, three endocrine and 17 exocrine, were cytogenetically analysed. All three endocrine tumours had a normal chromosome complement. Clonal chromosome aberrations were detected in 13 of the 17 exocrine tumours: simple karyotypic changes were found in five carcinomas and numerous numerical and/or structural changes in eight. When the present findings and those previously reported by our group were viewed in conjunction, the most common numerical imbalances among the 22 karyotypically abnormal pancreatic carcinomas thus available for evaluation turned out to be, in order of falling frequency, -18, -Y, +20, +7, +11 and -12. Imbalances brought about by structural changes most frequently affected chromosomes 1 (losses in 1p but especially gains of 1q), 8 (in particular 8q gains but also 8p losses), and 17 (mostly 17q gain but also loss of 17p). Chromosomal bands 1p32, 1q10, 6q21, 7p22, 8p21, 8q11, 14p11, 15q10-11, and 17q11 were the most common breakpoint sites affected by the structural rearrangements. Abnormal karyotypes were detected more frequently in poorly differentiated and anaplastic carcinomas than in moderately and well differentiated tumours. Images Figure 1 PMID:8494707

  4. Developmental alterations in centrosome integrity contribute to the post-mitotic state of mammalian cardiomyocytes.

    PubMed

    Zebrowski, David C; Vergarajauregui, Silvia; Wu, Chi-Chung; Piatkowski, Tanja; Becker, Robert; Leone, Marina; Hirth, Sofia; Ricciardi, Filomena; Falk, Nathalie; Giessl, Andreas; Just, Steffen; Braun, Thomas; Weidinger, Gilbert; Engel, Felix B

    2015-01-01

    Mammalian cardiomyocytes become post-mitotic shortly after birth. Understanding how this occurs is highly relevant to cardiac regenerative therapy. Yet, how cardiomyocytes achieve and maintain a post-mitotic state is unknown. Here, we show that cardiomyocyte centrosome integrity is lost shortly after birth. This is coupled with relocalization of various centrosome proteins to the nuclear envelope. Consequently, postnatal cardiomyocytes are unable to undergo ciliogenesis and the nuclear envelope adopts the function as cellular microtubule organizing center. Loss of centrosome integrity is associated with, and can promote, cardiomyocyte G0/G1 cell cycle arrest suggesting that centrosome disassembly is developmentally utilized to achieve the post-mitotic state in mammalian cardiomyocytes. Adult cardiomyocytes of zebrafish and newt, which are able to proliferate, maintain centrosome integrity. Collectively, our data provide a novel mechanism underlying the post-mitotic state of mammalian cardiomyocytes as well as a potential explanation for why zebrafish and newts, but not mammals, can regenerate their heart. PMID:26247711

  5. Mitotic rounding alters cell geometry to ensure efficient bipolar spindle formation.

    PubMed

    Lancaster, Oscar M; Le Berre, Maël; Dimitracopoulos, Andrea; Bonazzi, Daria; Zlotek-Zlotkiewicz, Ewa; Picone, Remigio; Duke, Thomas; Piel, Matthieu; Baum, Buzz

    2013-05-13

    Accurate animal cell division requires precise coordination of changes in the structure of the microtubule-based spindle and the actin-based cell cortex. Here, we use a series of perturbation experiments to dissect the relative roles of actin, cortical mechanics, and cell shape in spindle formation. We find that, whereas the actin cortex is largely dispensable for rounding and timely mitotic progression in isolated cells, it is needed to drive rounding to enable unperturbed spindle morphogenesis under conditions of confinement. Using different methods to limit mitotic cell height, we show that a failure to round up causes defects in spindle assembly, pole splitting, and a delay in mitotic progression. These defects can be rescued by increasing microtubule lengths and therefore appear to be a direct consequence of the limited reach of mitotic centrosome-nucleated microtubules. These findings help to explain why most animal cells round up as they enter mitosis.

  6. Phosphorylation of the proapoptotic BH3-only protein bid primes mitochondria for apoptosis during mitotic arrest.

    PubMed

    Wang, Pengbo; Lindsay, Jennefer; Owens, Thomas W; Mularczyk, Ewa J; Warwood, Stacey; Foster, Fiona; Streuli, Charles H; Brennan, Keith; Gilmore, Andrew P

    2014-05-01

    Mitosis is a moment of exquisite vulnerability for a metazoan cell. Failure to complete mitosis accurately can lead to aneuploidy and cancer initiation. Therefore, if the exit from mitosis is delayed, normal cells are usually removed by apoptosis. However, how failure to complete mitosis activates apoptosis is still unclear. Here, we demonstrate that a phosphorylated form of the BH3-only protein Bid regulates apoptosis if mitotic exit is delayed. Bid is phosphorylated on serine 66 as cells enter mitosis, and this phosphorylation is lost during the metaphase-to-anaphase transition. Cells expressing a nonphosphorylatable version of Bid or a BH3-domain mutant were resistant to mitotic-arrest-induced apoptosis. Thus, we show that Bid phosphorylation primes cells to undergo mitochondrial apoptosis if mitotic exit is delayed. Avoidance of this mechanism may explain the selective pressure for cancer cells to undergo mitotic slippage. PMID:24767991

  7. Suspension of mitotic activity in dentate gyrus of the hibernating ground squirrel.

    PubMed

    Popov, Victor I; Kraev, Igor V; Ignat'ev, Dmitri A; Stewart, Michael G

    2011-01-01

    Neurogenesis occurs in the adult mammalian hippocampus, a region of the brain important for learning and memory. Hibernation in Siberian ground squirrels provides a natural model to study mitosis as the rapid fall in body temperature in 24 h (from 35-36°C to +4-6°C) permits accumulation of mitotic cells at different stages of the cell cycle. Histological methods used to study adult neurogenesis are limited largely to fixed tissue, and the mitotic state elucidated depends on the specific phase of mitosis at the time of day. However, using an immunohistochemical study of doublecortin (DCX) and BrdU-labelled neurons, we demonstrate that the dentate gyrus of the ground squirrel hippocampus contains a population of immature cells which appear to possess mitotic activity. Our data suggest that doublecortin-labelled immature cells exist in a mitotic state and may represent a renewable pool for generation of new neurons within the dentate gyrus.

  8. Developmental alterations in centrosome integrity contribute to the post-mitotic state of mammalian cardiomyocytes.

    PubMed

    Zebrowski, David C; Vergarajauregui, Silvia; Wu, Chi-Chung; Piatkowski, Tanja; Becker, Robert; Leone, Marina; Hirth, Sofia; Ricciardi, Filomena; Falk, Nathalie; Giessl, Andreas; Just, Steffen; Braun, Thomas; Weidinger, Gilbert; Engel, Felix B

    2015-08-06

    Mammalian cardiomyocytes become post-mitotic shortly after birth. Understanding how this occurs is highly relevant to cardiac regenerative therapy. Yet, how cardiomyocytes achieve and maintain a post-mitotic state is unknown. Here, we show that cardiomyocyte centrosome integrity is lost shortly after birth. This is coupled with relocalization of various centrosome proteins to the nuclear envelope. Consequently, postnatal cardiomyocytes are unable to undergo ciliogenesis and the nuclear envelope adopts the function as cellular microtubule organizing center. Loss of centrosome integrity is associated with, and can promote, cardiomyocyte G0/G1 cell cycle arrest suggesting that centrosome disassembly is developmentally utilized to achieve the post-mitotic state in mammalian cardiomyocytes. Adult cardiomyocytes of zebrafish and newt, which are able to proliferate, maintain centrosome integrity. Collectively, our data provide a novel mechanism underlying the post-mitotic state of mammalian cardiomyocytes as well as a potential explanation for why zebrafish and newts, but not mammals, can regenerate their heart.

  9. The NOXA–MCL1–BIM axis defines lifespan on extended mitotic arrest

    PubMed Central

    Haschka, Manuel D.; Soratroi, Claudia; Kirschnek, Susanne; Häcker, Georg; Hilbe, Richard; Geley, Stephan; Villunger, Andreas; Fava, Luca L.

    2015-01-01

    Cell death on extended mitotic arrest is considered arguably most critical for the efficacy of microtubule-targeting agents (MTAs) in anticancer therapy. While the molecular machinery controlling mitotic arrest on MTA treatment, the spindle assembly checkpoint (SAC), appears well defined, the molecular components executing cell death, as well as factors connecting both networks remain poorly understood. Here we conduct a mini screen exploring systematically the contribution of individual BCL2 family proteins at single cell resolution to death on extended mitotic arrest, and demonstrate that the mitotic phosphorylation of BCL2 and BCLX represent a priming event for apoptosis that is ultimately triggered by NOXA-dependent MCL1 degradation, enabling BIM-dependent cell death. Our findings provide a comprehensive model for the initiation of apoptosis in cells stalled in mitosis and provide a molecular basis for the increased efficacy of combinatorial treatment of cancer cells using MTAs and BH3 mimetics. PMID:25922916

  10. Ictal Cardiac Ryhthym Abnormalities

    PubMed Central

    Ali, Rushna

    2016-01-01

    Cardiac rhythm abnormalities in the context of epilepsy are a well-known phenomenon. However, they are under-recognized and often missed. The pathophysiology of these events is unclear. Bradycardia and asystole are preceded by seizure onset suggesting ictal propagation into the cortex impacting cardiac autonomic function, and the insula and amygdala being possible culprits. Sudden unexpected death in epilepsy (SUDEP) refers to the unanticipated death of a patient with epilepsy not related to status epilepticus, trauma, drowning, or suicide. Frequent refractory generalized tonic-clonic seizures, anti-epileptic polytherapy, and prolonged duration of epilepsy are some of the commonly identified risk factors for SUDEP. However, the most consistent risk factor out of these is an increased frequency of generalized tonic–clonic seizures (GTC). Prevention of SUDEP is extremely important in patients with chronic, generalized epilepsy. Since increased frequency of GTCS is the most consistently reported risk factor for SUDEP, effective seizure control is the most important preventive strategy. PMID:27347227

  11. Ictal Cardiac Ryhthym Abnormalities.

    PubMed

    Ali, Rushna

    2016-01-01

    Cardiac rhythm abnormalities in the context of epilepsy are a well-known phenomenon. However, they are under-recognized and often missed. The pathophysiology of these events is unclear. Bradycardia and asystole are preceded by seizure onset suggesting ictal propagation into the cortex impacting cardiac autonomic function, and the insula and amygdala being possible culprits. Sudden unexpected death in epilepsy (SUDEP) refers to the unanticipated death of a patient with epilepsy not related to status epilepticus, trauma, drowning, or suicide. Frequent refractory generalized tonic-clonic seizures, anti-epileptic polytherapy, and prolonged duration of epilepsy are some of the commonly identified risk factors for SUDEP. However, the most consistent risk factor out of these is an increased frequency of generalized tonic-clonic seizures (GTC). Prevention of SUDEP is extremely important in patients with chronic, generalized epilepsy. Since increased frequency of GTCS is the most consistently reported risk factor for SUDEP, effective seizure control is the most important preventive strategy. PMID:27347227

  12. Communication and abnormal behaviour.

    PubMed

    Crown, S

    1979-01-01

    In this paper the similarities between normal and abnormal behaviour are emphasized and selected aspects of communication, normal and aberrant, between persons are explored. Communication in a social system may be verbal or non-verbal: one person's actions cause a response in another person. This response may be cognitive, behavioural or physiological. Communication may be approached through the individual, the social situation or social interaction. Psychoanalysis approaches the individual in terms of the coded communications of psychoneurotic symptoms or psychotic behaviour; the humanist-existential approach is concerned more with emotional expression. Both approaches emphasize the development of individual identity. The interaction between persons and their social background is stressed. Relevant are sociological concepts such as illness behaviour, stigma, labelling, institutionalization and compliance. Two approaches to social interactions are considered: the gamesplaying metaphor, e.g. back pain as a psychosocial manipulation--the 'pain game'; and the 'spiral of reciprocal perspectives' which emphasizes the interactional complexities of social perceptions. Communicatory aspects of psychological treatments are noted: learning a particular metaphor such as 'resolution' of the problem (psychotherapy), learning more 'rewarding' behaviour (learning theory) or learning authenticity or self-actualization (humanist-existential).

  13. Communication and abnormal behaviour.

    PubMed

    Crown, S

    1979-01-01

    In this paper the similarities between normal and abnormal behaviour are emphasized and selected aspects of communication, normal and aberrant, between persons are explored. Communication in a social system may be verbal or non-verbal: one person's actions cause a response in another person. This response may be cognitive, behavioural or physiological. Communication may be approached through the individual, the social situation or social interaction. Psychoanalysis approaches the individual in terms of the coded communications of psychoneurotic symptoms or psychotic behaviour; the humanist-existential approach is concerned more with emotional expression. Both approaches emphasize the development of individual identity. The interaction between persons and their social background is stressed. Relevant are sociological concepts such as illness behaviour, stigma, labelling, institutionalization and compliance. Two approaches to social interactions are considered: the gamesplaying metaphor, e.g. back pain as a psychosocial manipulation--the 'pain game'; and the 'spiral of reciprocal perspectives' which emphasizes the interactional complexities of social perceptions. Communicatory aspects of psychological treatments are noted: learning a particular metaphor such as 'resolution' of the problem (psychotherapy), learning more 'rewarding' behaviour (learning theory) or learning authenticity or self-actualization (humanist-existential). PMID:261653

  14. Abnormal uterine bleeding.

    PubMed

    Whitaker, Lucy; Critchley, Hilary O D

    2016-07-01

    Abnormal uterine bleeding (AUB) is a common and debilitating condition with high direct and indirect costs. AUB frequently co-exists with fibroids, but the relationship between the two remains incompletely understood and in many women the identification of fibroids may be incidental to a menstrual bleeding complaint. A structured approach for establishing the cause using the Fédération International de Gynécologie et d'Obstétrique (FIGO) PALM-COEIN (Polyp, Adenomyosis, Leiomyoma, Malignancy (and hyperplasia), Coagulopathy, Ovulatory disorders, Endometrial, Iatrogenic and Not otherwise classified) classification system will facilitate accurate diagnosis and inform treatment options. Office hysteroscopy and increasing sophisticated imaging will assist provision of robust evidence for the underlying cause. Increased availability of medical options has expanded the choice for women and many will no longer need to recourse to potentially complicated surgery. Treatment must remain individualised and encompass the impact of pressure symptoms, desire for retention of fertility and contraceptive needs, as well as address the management of AUB in order to achieve improved quality of life. PMID:26803558

  15. Abortion for fetal abnormality.

    PubMed

    Maclean, N E

    1979-07-25

    I wish to thank Dr. Pauline Bennett for her reply (NZ Med J, 13 June). She has demonstrated well that in dealing with sensitive difficult issues such as abortion for fetal abnormality, the one thing the doctor is not recommended to do is to speak the truth] I am prompted to write this letter for 2 reasons. Firstly, the excellent letter written by Dr. A. M. Rutherford (NZ Med J, 13 June) on the subject of abortion stated, "The most disturbing feature about the whole controversy is the 'blunting of our conscience'." When the doctors are not encouraged to be honest with patients then indeed our conscience has been blunted. Secondly, I watched Holocaust last night, and cannot refrain from stating that I see frightening parallels between our liberal abortion policy and the activities of the Nazis. As I watched the "mental patients" being herded into the shed for gassing by the polite, tidy, white coated medical staff, and then heard the compassionate, sensitive, letter of the hospital authorities to the relatives of the deceased, the parallel became obvious. The mental patients were weak, defenseless, burdensome, and uneconomic; the unborn are weak, defenseless, burdensome, and uneconomic. The hospital authority's letter was acceptable in many ways, acceptable except that its words bore no relation to the truth. It is said that the "first casualty of war is the truth". Whether that war involves the Jews, or the insane, or the unborn, the statement would seem correct.

  16. Maintaining Genome Stability in Defiance of Mitotic DNA Damage.

    PubMed

    Ferrari, Stefano; Gentili, Christian

    2016-01-01

    The implementation of decisions affecting cell viability and proliferation is based on prompt detection of the issue to be addressed, formulation and transmission of a correct set of instructions and fidelity in the execution of orders. While the first and the last are purely mechanical processes relying on the faithful functioning of single proteins or macromolecular complexes (sensors and effectors), information is the real cue, with signal amplitude, duration, and frequency ultimately determining the type of response. The cellular response to DNA damage is no exception to the rule. In this review article we focus on DNA damage responses in G2 and Mitosis. First, we set the stage describing mitosis and the machineries in charge of assembling the apparatus responsible for chromosome alignment and segregation as well as the inputs that control its function (checkpoints). Next, we examine the type of issues that a cell approaching mitosis might face, presenting the impact of post-translational modifications (PTMs) on the correct and timely functioning of pathways correcting errors or damage before chromosome segregation. We conclude this essay with a perspective on the current status of mitotic signaling pathway inhibitors and their potential use in cancer therapy. PMID:27493659

  17. Telomere loss: mitotic clock or genetic time bomb?

    PubMed

    Harley, C B

    1991-01-01

    The Holy Grail of gerontologists investigating cellular senescence is the mechanism responsible for the finite proliferative capacity of somatic cells. In 1973, Olovnikov proposed that cells lose a small amount of DNA following each round of replication due to the inability of DNA polymerase to fully replicate chromosome ends (telomeres) and that eventually a critical deletion causes cell death. Recent observations showing that telomeres of human somatic cells act as a mitotic clock, shortening with age both in vitro and in vivo in a replication dependent manner, support this theory's premise. In addition, since telomeres stabilize chromosome ends against recombination, their loss could explain the increased frequency of dicentric chromosomes observed in late passage (senescent) fibroblasts and provide a checkpoint for regulated cell cycle exit. Sperm telomeres are longer than somatic telomeres and are maintained with age, suggesting that germ line cells may express telomerase, the ribonucleoprotein enzyme known to maintain telomere length in immortal unicellular eukaryotes. As predicted, telomerase activity has been found in immortal, transformed human cells and tumour cell lines, but not in normal somatic cells. Telomerase activation may be a late, obligate event in immortalization since many transformed cells and tumour tissues have critically short telomeres. Thus, telomere length and telomerase activity appear to be markers of the replicative history and proliferative potential of cells; the intriguing possibility remains that telomere loss is a genetic time bomb and hence causally involved in cell senescence and immortalization.

  18. Maintaining Genome Stability in Defiance of Mitotic DNA Damage

    PubMed Central

    Ferrari, Stefano; Gentili, Christian

    2016-01-01

    The implementation of decisions affecting cell viability and proliferation is based on prompt detection of the issue to be addressed, formulation and transmission of a correct set of instructions and fidelity in the execution of orders. While the first and the last are purely mechanical processes relying on the faithful functioning of single proteins or macromolecular complexes (sensors and effectors), information is the real cue, with signal amplitude, duration, and frequency ultimately determining the type of response. The cellular response to DNA damage is no exception to the rule. In this review article we focus on DNA damage responses in G2 and Mitosis. First, we set the stage describing mitosis and the machineries in charge of assembling the apparatus responsible for chromosome alignment and segregation as well as the inputs that control its function (checkpoints). Next, we examine the type of issues that a cell approaching mitosis might face, presenting the impact of post-translational modifications (PTMs) on the correct and timely functioning of pathways correcting errors or damage before chromosome segregation. We conclude this essay with a perspective on the current status of mitotic signaling pathway inhibitors and their potential use in cancer therapy. PMID:27493659

  19. Physical Description of Mitotic Spindle Orientation During Cell Division

    NASA Astrophysics Data System (ADS)

    Jiménez-Dalmaroni, Andrea; Théry, Manuel; Racine, Victor; Bornens, Michel; Jülicher, Frank

    2009-03-01

    During cell division, the duplicated chromosomes are physically separated by the action of the mitotic spindle. The spindle is a dynamic structure of the cytoskeleton, which consists of two microtubule asters. Its orientation defines the axis along which the cell divides. Recent experiments show that the spindle orientation depends on the spatial distribution of cell adhesion sites. Here we show that the experimentally observed spindle orientation can be understood as the result of the action of cortical force generators acting on the spindle. We assume that the local activity of force generators is controlled by the spatial distribution of cell adhesion sites determined by the particular geometry of the adhesive substrate. We develop a simple physical description of the spindle mechanics, which allows us to calculate the torque acting on the spindle, as well as the energy profile and the angular distribution of spindle orientation. Our model accounts for the preferred spindle orientation, as well as the full shape of the angular distributions of spindle orientation observed in a large variety of pattern geometries. M. Th'ery, A. Jim'enez-Dalmaroni, et al., Nature 447, 493 (2007).

  20. Relative contributions of chromatin and kinetochores to mitotic spindle assembly

    PubMed Central

    Lončarek, Jadranka; Kaláb, Petr; Khodjakov, Alexey

    2009-01-01

    During mitosis and meiosis in animal cells, chromosomes actively participate in spindle assembly by generating a gradient of Ran guanosine triphosphate (RanGTP). A high concentration of RanGTP promotes microtubule nucleation and stabilization in the vicinity of chromatin. However, the relative contributions of chromosome arms and centromeres/kinetochores in this process are not known. In this study, we address this issue using cells undergoing mitosis with unreplicated genomes (MUG). During MUG, chromatin is rapidly separated from the forming spindle, and both centrosomal and noncentrosomal spindle assembly pathways are active. MUG chromatin is coated with RCC1 and establishes a RanGTP gradient. However, a robust spindle forms around kinetochores/centromeres outside of the gradient peak. When stable kinetochore microtubule attachment is prevented by Nuf2 depletion in both MUG and normal mitosis, chromatin attracts astral microtubules but cannot induce spindle assembly. These results support a model in which kinetochores play the dominant role in the chromosome-mediated pathway of mitotic spindle assembly. PMID:19805628

  1. Regulation of mitotic spindle orientation: an integrated view.

    PubMed

    di Pietro, Florencia; Echard, Arnaud; Morin, Xavier

    2016-08-01

    Mitotic spindle orientation is essential for cell fate decisions, epithelial maintenance, and tissue morphogenesis. In most animal cell types, the dynein motor complex is anchored at the cell cortex and exerts pulling forces on astral microtubules to position the spindle. Early studies identified the evolutionarily conserved Gαi/LGN/NuMA complex as a key regulator that polarizes cortical force generators. In recent years, a combination of genetics, biochemistry, modeling, and live imaging has contributed to decipher the mechanisms of spindle orientation. Here, we highlight the dynamic nature of the assembly of this complex and discuss the molecular regulation of its localization. Remarkably, a number of LGN-independent mechanisms were described recently, whereas NuMA remains central in most pathways involved in recruiting force generators at the cell cortex. We also describe the emerging role of the actin cortex in spindle orientation and discuss how dynamic astral microtubule formation is involved. We further give an overview on instructive external signals that control spindle orientation in tissues. Finally, we discuss the influence of cell geometry and mechanical forces on spindle orientation. PMID:27432284

  2. Centrin: Another target of monastrol, an inhibitor of mitotic spindle

    NASA Astrophysics Data System (ADS)

    Duan, Lian; Wang, Tong-Qing; Bian, Wei; Liu, Wen; Sun, Yue; Yang, Bin-Sheng

    2015-02-01

    Monastrol, a cell-permeable inhibitor, considered to specifically inhibit kinesin Eg5, can cause mitotic arrest and monopolar spindle formation, thus exhibiting antitumor properties. Centrin, a ubiquitous protein associated with centrosome, plays a critical role in centrosome duplication. Moreover, a correlation between centrosome amplification and cancer has been reported. In this study, it is proposed for the first time that centrin may be another target of the anticancer drug monastrol since monastrol can effectively inhibit not only the growth of the transformed Escherichia coli cells in vivo, but also the Lu3+-dependent self-assembly of EoCen in vitro. The two closely related compounds (Compounds 1 and 2) could not take the same effect. Fluorescence titration experiments suggest that four monastrols per protein is the optimum binding pattern, and the binding constants at different temperatures were obtained. Detailed thermodynamic analysis indicates that hydrophobic force is the main acting force between monastrol and centrin, and the extent of monastrol inhibition of centrin self-assembly is highly dependent upon the hydrophobic region of the protein, which is largely exposed by the binding of metal ions.

  3. Multiscale diffusion in the mitotic Drosophila melanogaster syncytial blastoderm.

    PubMed

    Daniels, Brian R; Rikhy, Richa; Renz, Malte; Dobrowsky, Terrence M; Lippincott-Schwartz, Jennifer

    2012-05-29

    Despite the fundamental importance of diffusion for embryonic morphogen gradient formation in the early Drosophila melanogaster embryo, there remains controversy regarding both the extent and the rate of diffusion of well-characterized morphogens. Furthermore, the recent observation of diffusional "compartmentalization" has suggested that diffusion may in fact be nonideal and mediated by an as-yet-unidentified mechanism. Here, we characterize the effects of the geometry of the early syncytial Drosophila embryo on the effective diffusivity of cytoplasmic proteins. Our results demonstrate that the presence of transient mitotic membrane furrows results in a multiscale diffusion effect that has a significant impact on effective diffusion rates across the embryo. Using a combination of live-cell experiments and computational modeling, we characterize these effects and relate effective bulk diffusion rates to instantaneous diffusion coefficients throughout the syncytial blastoderm nuclear cycle phase of the early embryo. This multiscale effect may be related to the effect of interphase nuclei on effective diffusion, and thus we propose that an as-yet-unidentified role of syncytial membrane furrows is to temporally regulate bulk embryonic diffusion rates to balance the multiscale effect of interphase nuclei, which ultimately stabilizes the shapes of various morphogen gradients.

  4. Variations in the association of papillomavirus E2 proteins with mitotic chromosomes

    PubMed Central

    Oliveira, Jaquelline G.; Colf, Leremy A.; McBride, Alison A.

    2006-01-01

    The E2 protein segregates episomal bovine papillomavirus (BPV) genomes to daughter cells by tethering them to mitotic chromosomes, thus ensuring equal distribution and retention of viral DNA. To date, only the BPV1 E2 protein has been shown to bind to mitotic chromosomes. We assessed the localization of 13 different animal and human E2 proteins from seven papillomavirus genera, and we show that most of them are stably bound to chromosomes throughout mitosis. Furthermore, in contrast to the random association of BPV1 E2 with mitotic chromosomes, several of these proteins appear to bind to more specific regions of mitotic chromosomes. Using human papillomavirus (HPV) type 8 E2, we show that this region is adjacent to centromeres/kinetochores. Therefore, E2 proteins from both HPV and animal papillomavirus bind to mitotic chromosomes, and there are variations in the specificity of this binding. Only the α-papillomavirus E2 proteins do not stably associate with mitotic chromatin throughout mitosis. These proteins closely associate with prophase chromosomes and bind to chromosomes in telophase but not in metaphase. However, extraction of mitotic cells before fixation results in α-E2 proteins binding to the pericentromeric region of metaphase chromosomes, as observed for HPV8 E2. We postulate that this is the authentic target of these E2 proteins but that additional factors or a specialized cellular environment is required to stabilize this association. Thus, E2-mediated tethering of viral genomes to mitotic chromosomes is a common strategy of papillomaviruses, but different viruses have evolved different variations of this theme. PMID:16415162

  5. The Structure of the Mitotic Spindle and Nucleolus during Mitosis in the Amebo-Flagellate Naegleria

    PubMed Central

    Walsh, Charles J.

    2012-01-01

    Mitosis in the amebo-flagellate Naegleria pringsheimi is acentrosomal and closed (the nuclear membrane does not break down). The large central nucleolus, which occupies about 20% of the nuclear volume, persists throughout the cell cycle. At mitosis, the nucleolus divides and moves to the poles in association with the chromosomes. The structure of the mitotic spindle and its relationship to the nucleolus are unknown. To identify the origin and structure of the mitotic spindle, its relationship to the nucleolus and to further understand the influence of persistent nucleoli on cellular division in acentriolar organisms like Naegleria, three-dimensional reconstructions of the mitotic spindle and nucleolus were carried out using confocal microscopy. Monoclonal antibodies against three different nucleolar regions and α-tubulin were used to image the nucleolus and mitotic spindle. Microtubules were restricted to the nucleolus beginning with the earliest prophase spindle microtubules. Early spindle microtubules were seen as short rods on the surface of the nucleolus. Elongation of the spindle microtubules resulted in a rough cage of microtubules surrounding the nucleolus. At metaphase, the mitotic spindle formed a broad band completely embedded within the nucleolus. The nucleolus separated into two discreet masses connected by a dense band of microtubules as the spindle elongated. At telophase, the distal ends of the mitotic spindle were still completely embedded within the daughter nucleoli. Pixel by pixel comparison of tubulin and nucleolar protein fluorescence showed 70% or more of tubulin co-localized with nucleolar proteins by early prophase. These observations suggest a model in which specific nucleolar binding sites for microtubules allow mitotic spindle formation and attachment. The fact that a significant mass of nucleolar material precedes the chromosomes as the mitotic spindle elongates suggests that spindle elongation drives nucleolar division. PMID:22493714

  6. Ion beam figuring of silicon aspheres

    NASA Astrophysics Data System (ADS)

    Demmler, Marcel; Zeuner, Michael; Luca, Alfonz; Dunger, Thoralf; Rost, Dirk; Kiontke, Sven; Krüger, Marcus

    2011-03-01

    Silicon lenses are widely used for infrared applications. Especially for portable devices the size and weight of the optical system are very important factors. The use of aspherical silicon lenses instead of spherical silicon lenses results in a significant reduction of weight and size. The manufacture of silicon lenses is more challenging than the manufacture of standard glass lenses. Typically conventional methods like diamond turning, grinding and polishing are used. However, due to the high hardness of silicon, diamond turning is very difficult and requires a lot of experience. To achieve surfaces of a high quality a polishing step is mandatory within the manufacturing process. Nevertheless, the required surface form accuracy cannot be achieved through the use of conventional polishing methods because of the unpredictable behavior of the polishing tools, which leads to an unstable removal rate. To overcome these disadvantages a method called Ion Beam Figuring can be used to manufacture silicon lenses with high surface form accuracies. The general advantage of the Ion Beam Figuring technology is a contactless polishing process without any aging effects of the tool. Due to this an excellent stability of the removal rate without any mechanical surface damage is achieved. The related physical process - called sputtering - can be applied to any material and is therefore also applicable to materials of high hardness like Silicon (SiC, WC). The process is realized through the commercially available ion beam figuring system IonScan 3D. During the process, the substrate is moved in front of a focused broad ion beam. The local milling rate is controlled via a modulated velocity profile, which is calculated specifically for each surface topology in order to mill the material at the associated positions to the target geometry. The authors will present aspherical silicon lenses with very high surface form accuracies compared to conventionally manufactured lenses.

  7. A Mathematical Model of Mitotic Exit in Budding Yeast: The Role of Polo Kinase

    PubMed Central

    Hancioglu, Baris; Tyson, John J.

    2012-01-01

    Cell cycle progression in eukaryotes is regulated by periodic activation and inactivation of a family of cyclin–dependent kinases (Cdk's). Entry into mitosis requires phosphorylation of many proteins targeted by mitotic Cdk, and exit from mitosis requires proteolysis of mitotic cyclins and dephosphorylation of their targeted proteins. Mitotic exit in budding yeast is known to involve the interplay of mitotic kinases (Cdk and Polo kinases) and phosphatases (Cdc55/PP2A and Cdc14), as well as the action of the anaphase promoting complex (APC) in degrading specific proteins in anaphase and telophase. To understand the intricacies of this mechanism, we propose a mathematical model for the molecular events during mitotic exit in budding yeast. The model captures the dynamics of this network in wild-type yeast cells and 110 mutant strains. The model clarifies the roles of Polo-like kinase (Cdc5) in the Cdc14 early anaphase release pathway and in the G-protein regulated mitotic exit network. PMID:22383977

  8. Aurora A kinase modulates actin cytoskeleton through phosphorylation of Cofilin: Implication in the mitotic process.

    PubMed

    Ritchey, Lisa; Chakrabarti, Ratna

    2014-11-01

    Aurora A kinase regulates early mitotic events through phosphorylation and activation of a variety of proteins. Specifically, Aur-A is involved in centrosomal separation and formation of mitotic spindles in early prophase. The effect of Aur-A on mitotic spindles is mediated by the modulation of microtubule dynamics and association with microtubule binding proteins. In this study we show that Aur-A exerts its effects on spindle organization through the regulation of the actin cytoskeleton. Aurora A phosphorylates Cofilin at multiple sites including S(3) resulting in the inactivation of its actin depolymerizing function. Aur-A interacts with Cofilin in early mitotic phases and regulates its phosphorylation status. Cofilin phosphorylation follows a dynamic pattern during the progression of prophase to metaphase. Inhibition of Aur-A activity induced a delay in the progression of prophase to metaphase. Aur-A inhibitor also disturbed the pattern of Cofilin phosphorylation, which correlated with the mitotic delay. Our results establish a novel function of Aur-A in the regulation of actin cytoskeleton reorganization, through Cofilin phosphorylation during early mitotic stages.

  9. AMPK regulates mitotic spindle orientation through phosphorylation of myosin regulatory light chain.

    PubMed

    Thaiparambil, Jose T; Eggers, Carrie M; Marcus, Adam I

    2012-08-01

    The proper orientation of the mitotic spindle is essential for mitosis; however, how these events unfold at the molecular level is not well understood. AMP-activated protein kinase (AMPK) regulates energy homeostasis in eukaryotes, and AMPK-null Drosophila mutants have spindle defects. We show that threonine(172) phosphorylated AMPK localizes to the mitotic spindle poles and increases when cells enter mitosis. AMPK depletion causes a mitotic delay with misoriented spindles relative to the normal division plane and a reduced number and length of astral microtubules. AMPK-depleted cells contain mitotic actin bundles, which prevent astral microtubule-actin cortex attachments. Since myosin regulatory light chain (MRLC) is an AMPK downstream target and mediates actin function, we investigated whether AMPK signals through MRLC to control spindle orientation. Mitotic levels of serine(19) phosphorylated MRLC (pMRLC(ser19)) and spindle pole-associated pMRLC(ser19) are abolished when AMPK function is compromised, indicating that AMPK is essential for pMRLC(ser19) spindle pole activity. Phosphorylation of AMPK and MRLC in the mitotic spindle is dependent upon calcium/calmodulin-dependent protein kinase kinase (CamKK) activity in LKB1-deficient cells, suggesting that CamKK regulates this pathway when LKB1 function is compromised. Taken together, these data indicate that AMPK mediates spindle pole-associated pMRLC(ser19) to control spindle orientation via regulation of actin cortex-astral microtubule attachments.

  10. Myosin-10 and actin filaments are essential for mitotic spindle function

    PubMed Central

    Woolner, Sarah; O'Brien, Lori L.; Wiese, Christiane; Bement, William M.

    2008-01-01

    Mitotic spindles are microtubule-based structures responsible for chromosome partitioning during cell division. Although the roles of microtubules and microtubule-based motors in mitotic spindles are well established, whether or not actin filaments (F-actin) and F-actin–based motors (myosins) are required components of mitotic spindles has long been controversial. Based on the demonstration that myosin-10 (Myo10) is important for assembly of meiotic spindles, we assessed the role of this unconventional myosin, as well as F-actin, in mitotic spindles. We find that Myo10 localizes to mitotic spindle poles and is essential for proper spindle anchoring, normal spindle length, spindle pole integrity, and progression through metaphase. Furthermore, we show that F-actin localizes to mitotic spindles in dynamic cables that surround the spindle and extend between the spindle and the cortex. Remarkably, although proper anchoring depends on both F-actin and Myo10, the requirement for Myo10 in spindle pole integrity is F-actin independent, whereas F-actin and Myo10 actually play antagonistic roles in maintenance of spindle length. PMID:18606852

  11. Histone deacetylase inhibitors disrupt the mitotic spindle assembly checkpoint by targeting histone and nonhistone proteins.

    PubMed

    Gabrielli, Brian; Brown, Mellissa

    2012-01-01

    Histone deacetylase inhibitors exhibit pleiotropic effects on cell functions, both in vivo and in vitro. One of the more dramatic effects of these drugs is their ability to disrupt normal mitotic division, which is a significant contributor to the anticancer properties of these drugs. The most important feature of the disrupted mitosis is that drug treatment overcomes the mitotic spindle assembly checkpoint and drives mitotic slippage, but in a manner that triggers apoptosis. The mechanism by which histone deacetylase inhibitors affect mitosis is now becoming clearer through the identification of a number of chromatin and nonchromatin protein targets that are critical to the regulation of normal mitotic progression and cell division. These proteins are directly regulated by acetylation and deacetylation, or in some cases indirectly through the acetylation of essential partner proteins. There appears to be little contribution from deacetylase inhibitor-induced transcriptional changes to the mitotic effects of these drugs. The overall mitotic phenotype of drug treatment appears to be the sum of these disrupted mechanisms. PMID:23088867

  12. Identification of Mitosis-Specific Phosphorylation in Mitotic Chromosome-Associated Proteins.

    PubMed

    Ohta, Shinya; Kimura, Michiko; Takagi, Shunsuke; Toramoto, Iyo; Ishihama, Yasushi

    2016-09-01

    During mitosis, phosphorylation of chromosome-associated proteins is a key regulatory mechanism. Mass spectrometry has been successfully applied to determine the complete protein composition of mitotic chromosomes, but not to identify post-translational modifications. Here, we quantitatively compared the phosphoproteome of isolated mitotic chromosomes with that of chromosomes in nonsynchronized cells. We identified 4274 total phosphorylation sites and 350 mitosis-specific phosphorylation sites in mitotic chromosome-associated proteins. Significant mitosis-specific phosphorylation in centromere/kinetochore proteins was detected, although the chromosomal association of these proteins did not change throughout the cell cycle. This mitosis-specific phosphorylation might play a key role in regulation of mitosis. Further analysis revealed strong dependency of phosphorylation dynamics on kinase consensus patterns, thus linking the identified phosphorylation sites to known key mitotic kinases. Remarkably, chromosomal axial proteins such as non-SMC subunits of condensin, TopoIIα, and Kif4A, together with the chromosomal periphery protein Ki67 involved in the establishment of the mitotic chromosomal structure, demonstrated high phosphorylation during mitosis. These findings suggest a novel mechanism for regulation of chromosome restructuring in mitosis via protein phosphorylation. Our study generated a large quantitative database on protein phosphorylation in mitotic and nonmitotic chromosomes, thus providing insights into the dynamics of chromatin protein phosphorylation at mitosis onset.

  13. The Mitotic Checkpoint Gene, SIL is Regulated by E2F1

    PubMed Central

    Erez, Ayelet; Chaussepied, Marie; Tina, Colaizzo-Anas; Aplan, Peter; Ginsberg, Doron; Izraeli, Shai

    2009-01-01

    The SIL gene expression is increased in multiple cancers and correlates with the expression of mitotic spindle checkpoint genes and with increased metastatic potential. SIL regulates mitotic entry, organization of the mitotic spindle and cell survival. The E2F transcription factors regulate cell cycle progression by controlling the expression of genes mediating the G1/S transition. More recently E2F has been shown to regulate mitotic spindle checkpoint genes as well. As SIL expression correlates with mitotic checkpoint genes we hypothesized that SIL is regulated by E2F. We mined raw data of published experiments and performed new experiments by modification of E2F expression in cell lines, reporter assays and chromatin immunoprecipitation. Ectopic expression or endogenous activation of E2F induced the expression of SIL, while knockdown of E2F by shRNA, downregulated SIL expression. E2F activated SIL promoter by reporter assay and bound to SIL promoter in-vivo. Taken together these data demonstrate that SIL is regulated by E2F. As SIL is essential for mitotic entry, E2F may regulate G2/M transition through the induction of SIL. Furthermore, as silencing of SIL cause apoptosis in cancer cells, these finding may have therapeutic relevance in tumors with constitutive activation of E2F. PMID:18649360

  14. Figures of merit for laser beam quality

    NASA Technical Reports Server (NTRS)

    Milster, T. D.; Walker, E. P.

    1993-01-01

    It was shown how full-width at half maximum (FWHM), full-width at 1/e(sup 2) (FW1/e(sup 2)), Strehl ratio, and encircled energy figures of merit vary with different types of aberration and measurement methods. The array sampling method and the slit-scan method are examined in detail. Our irradiance in the exit pupil of the optical system is a simple gaussian. It was found that in general the slit-scan method and the array method do not yield the same result. The width measurements for the central lobe of the diffraction pattern are very insensitive to aberration.

  15. Infrared thermal imaging figures of merit

    NASA Technical Reports Server (NTRS)

    Kaplan, Herbert

    1989-01-01

    Commercially available types of infrared thermal imaging instruments, both viewers (qualitative) and imagers (quantitative) are discussed. The various scanning methods by which thermal images (thermograms) are generated will be reviewed. The performance parameters (figures of merit) that define the quality of performance of infrared radiation thermometers will be introduced. A discussion of how these parameters are extended and adapted to define the performance of thermal imaging instruments will be provided. Finally, the significance of each of the key performance parameters of thermal imaging instruments will be reviewed and procedures currently used for testing to verify performance will be outlined.

  16. High LET radiation enhances nocodazole Induced cell death in HeLa cells through mitotic catastrophe and apoptosis.

    PubMed

    Li, Ping; Zhou, Libin; Dai, Zhongying; Jin, Xiaodong; Liu, Xinguo; Matsumoto, Yoshitaka; Furusawa, Yoshiya; Li, Qiang

    2011-01-01

    To understand how human tumor cells respond to the combined treatment with nocodazole and high LET radiation, alterations in cell cycle, mitotic disturbances and cell death were investigated in the present study. Human cervix carcinoma HeLa cells were exposed to nocodazole for 18 h immediately followed by high LET iron ion irradiation and displayed a sequence of events leading to DNA damages, mitotic aberrations, interphase restitution and endocycle as well as cell death. A prolonged mitotic arrest more than 10 h was observed following nocodazole exposure, no matter the irradiation was present or not. The occurrence of mitotic slippage following the mitotic arrest was only drug-dependent and the irradiation did not accelerate it. The amount of polyploidy cells was increased following mitotic slippage. No detectable G(2) or G(1) arrest was observed in cells upon the combined treatment and the cells reentered the cell cycle still harboring unrepaired cellular damages. This premature entry caused an increase of multipolar mitotic spindles and amplification of centrosomes, which gave rise to lagging chromosomal material, failure of cytokinesis and polyploidization. These mitotic disturbances and their outcomes confirmed the incidence of mitotic catastrophe and delayed apoptotic features displayed by TUNEL method after the combined treatment. These results suggest that the addition of high-LET iron ion irradiation to nocodazole enhanced mitotic catastrophe and delayed apoptosis in HeLa cells. These might be important cell death mechanisms involved in tumor cells in response to the treatment of antimitotic drug combined with high LET radiation.

  17. Suppression of microtubule dynamics by discodermolide by a novel mechanism is associated with mitotic arrest and inhibition of tumor cell proliferation.

    PubMed

    Honore, Stéphane; Kamath, Kathy; Braguer, Diane; Wilson, Leslie; Briand, Claudette; Jordan, Mary Ann

    2003-12-01

    Discodermolide is a new microtubule-targeted drug in Phase I clinical trials that inhibits tumor growth and induces G(2)-M cell cycle arrest. It is effective against paclitaxel-resistant cell lines and acts synergistically in combination with paclitaxel. Suppression of microtubule dynamics by microtubule-targeted drugs has been hypothesized to be responsible for their ability to inhibit mitotic progression and cell proliferation. To determine whether discodermolide blocks mitosis by an effect on microtubule dynamics, we analyzed the effects of discodermolide on microtubule dynamics in living A549 human lung cancer cells during interphase at concentrations that block mitosis and inhibit cell proliferation. We found that discodermolide (7-166 nM) significantly suppressed microtubule dynamic instability. At the IC(50) for proliferation (7 nM discodermolide, 72 h), overall dynamicity was reduced by 23%. The principal parameters of dynamic instability suppressed by discodermolide were the microtubule shortening rate and length shortened. In addition, discodermolide markedly increased the frequency of rescued catastrophes. At the discodermolide concentration that resulted in 50% of maximal mitotic block (83 nM, 20 h), most microtubules were completely non-dynamic, no anaphases occurred, and all spindles were abnormal. The dynamicity of the remaining dynamic microtubules was reduced by 62%. The results indicate that a principal mechanism of inhibition of cell proliferation and mitotic block by discodermolide is suppression of microtubule dynamics. Importantly, the results indicate significant additional stabilizing effects of discodermolide on microtubule dynamics as compared with those of paclitaxel that may in turn reflect differences in their binding sites and their effects on tubulin conformation.

  18. Haem degradation in abnormal haemoglobins.

    PubMed Central

    Brown, S B; Docherty, J C

    1978-01-01

    The coupled oxidation of certain abnormal haemoglobins leads to different bile-pigment isomer distributions from that of normal haemoglobin. The isomer pattern may be correlated with the structure of the abnormal haemoglobin in the neighbourhood of the haem pocket. This is support for haem degradation by an intramolecular reaction. PMID:708385

  19. Systemic abnormalities in liver disease

    PubMed Central

    Minemura, Masami; Tajiri, Kazuto; Shimizu, Yukihiro

    2009-01-01

    Systemic abnormalities often occur in patients with liver disease. In particular, cardiopulmonary or renal diseases accompanied by advanced liver disease can be serious and may determine the quality of life and prognosis of patients. Therefore, both hepatologists and non-hepatologists should pay attention to such abnormalities in the management of patients with liver diseases. PMID:19554648

  20. Abnormal pressure in hydrocarbon environments

    USGS Publications Warehouse

    Law, B.E.; Spencer, C.W.

    1998-01-01

    Abnormal pressures, pressures above or below hydrostatic pressures, occur on all continents in a wide range of geological conditions. According to a survey of published literature on abnormal pressures, compaction disequilibrium and hydrocarbon generation are the two most commonly cited causes of abnormally high pressure in petroleum provinces. In young (Tertiary) deltaic sequences, compaction disequilibrium is the dominant cause of abnormal pressure. In older (pre-Tertiary) lithified rocks, hydrocarbon generation, aquathermal expansion, and tectonics are most often cited as the causes of abnormal pressure. The association of abnormal pressures with hydrocarbon accumulations is statistically significant. Within abnormally pressured reservoirs, empirical evidence indicates that the bulk of economically recoverable oil and gas occurs in reservoirs with pressure gradients less than 0.75 psi/ft (17.4 kPa/m) and there is very little production potential from reservoirs that exceed 0.85 psi/ft (19.6 kPa/m). Abnormally pressured rocks are also commonly associated with unconventional gas accumulations where the pressuring phase is gas of either a thermal or microbial origin. In underpressured, thermally mature rocks, the affected reservoirs have most often experienced a significant cooling history and probably evolved from an originally overpressured system.

  1. Electrocardiograph abnormalities revealed during laparoscopy.

    PubMed

    Nijjer, Sukhjinder; Dubrey, Simon William

    2010-01-01

    This brief case presents a well patient in whom an electrocardiograph abnormality consistent with an accessory pathway was found during a routine procedure. We present the electrocardiographs, explain the underlying condition, and consider why the abnormality was revealed in this manner.

  2. Surface figure control for coated optics

    DOEpatents

    Ray-Chaudhuri, Avijit K.; Spence, Paul A.; Kanouff, Michael P.

    2001-01-01

    A pedestal optical substrate that simultaneously provides high substrate dynamic stiffness, provides low surface figure sensitivity to mechanical mounting hardware inputs, and constrains surface figure changes caused by optical coatings to be primarily spherical in nature. The pedestal optical substrate includes a disk-like optic or substrate section having a top surface that is coated, a disk-like base section that provides location at which the substrate can be mounted, and a connecting cylindrical section between the base and optics or substrate sections. The optic section has an optical section thickness.sup.2 /optical section diameter ratio of between about 5 to 10 mm, and a thickness variation between front and back surfaces of less than about 10%. The connecting cylindrical section may be attached via three spaced legs or members. However, the pedestal optical substrate can be manufactured from a solid piece of material to form a monolith, thus avoiding joints between the sections, or the disk-like base can be formed separately and connected to the connecting section. By way of example, the pedestal optical substrate may be utilized in the fabrication of optics for an extreme ultraviolet (EUV) lithography imaging system, or in any optical system requiring coated optics and substrates with reduced sensitivity to mechanical mounts.

  3. Figures of Merit for Lunar Simulants

    NASA Astrophysics Data System (ADS)

    Slane, Frederick

    The collection and analysis of lunar samples from 1969 to present has yielded large amounts of data. Published analyses give some idea of the complex nature of the regolith at all scales, rocks, soils and the smaller particulates commonly referred to as dust. Data recently acquired in support of NASA's simulant effort has markedly increased our knowledge and quantitatively demonstrates that complexity. It is anticipated that future analyses will further add to the known complexity. In an effort to communicate among the diverse technical communities performing research on or research using regolith samples and simulants, a set of Figures of Merit (FoM) have been devised. The objective is to allow consistent and concise comparative communication between researchers from multiple organizations and nations engaged in lunar exploration. This paper describes Figures of Merit in a working draft of an international standard for Lunar Simulants. The FoM methodology uses scientific understanding of the lunar samples to formulate parameters which are reproducibly quantifiable. Advanced work at NASA has evolved this effort to the point that formal definitions, supporting mathematics and functioning code have implemented the concept for testing.

  4. Feature Assignment in Perception of Auditory Figure

    PubMed Central

    Gregg, Melissa K.; Samuel, Arthur G.

    2012-01-01

    Because the environment often includes multiple sounds that overlap in time, listeners must segregate a sound of interest (the auditory figure) from other co-occurring sounds (the unattended auditory ground). We conducted a series of experiments to clarify the principles governing the extraction of auditory figures. We distinguish between auditory “objects” (relatively punctate events, such as a dog's bark) and auditory “streams” (sounds involving a pattern over time, such as a galloping rhythm). In Experiments 1 and 2, on each trial two sounds -- an object (a vowel) and a stream (a series of tones) – were presented with one target feature that could be perceptually grouped with either source. In each block of these experiments, listeners were required to attend to one of the two sounds, and report its perceived category. Across several experimental manipulations, listeners were more likely to allocate the feature to an impoverished object if the result of the grouping was a good, identifiable object. Perception of objects was quite sensitive to feature variation (noise masking), whereas perception of streams was more robust to feature variation. In Experiment 3, the number of sound sources competing for the feature was increased to three. This produced a shift toward relying more on spatial cues than on the potential contribution of the feature to an object's perceptual quality. The results support a distinction between auditory objects and streams, and provide new information about the way that the auditory world is parsed. PMID:22288691

  5. Whatever Became of Significant Figures? The Trend Toward Numerical Illiteracy.

    ERIC Educational Resources Information Center

    Anderlik, Barbara

    1980-01-01

    Discusses the problems associated with teaching uncertainties in measurements and significant figures. Appendices present an experiment on measurement that introduces uncertainty in measurement, and an exercise in significant figures. (CS)

  6. Nitrogen deficiency inhibits leaf blade growth in Lolium perenne by increasing cell cycle duration and decreasing mitotic and post-mitotic growth rates.

    PubMed

    Kavanová, Monika; Lattanzi, Fernando Alfredo; Schnyder, Hans

    2008-06-01

    Nitrogen deficiency severely inhibits leaf growth. This response was analysed at the cellular level by growing Lolium perenne L. under 7.5 mM (high) or 1 mM (low) nitrate supply, and performing a kinematic analysis to assess the effect of nitrogen status on cell proliferation and cell growth in the leaf blade epidermis. Low nitrogen supply reduced leaf elongation rate (LER) by 43% through a similar decrease in the cell production rate and final cell length. The former was entirely because of a decreased average cell division rate (0.023 versus 0.032 h(-1)) and thus longer cell cycle duration (30 versus 22 h). Nitrogen status did not affect the number of division cycles of the initial cell's progeny (5.7), and accordingly the meristematic cell number (53). Meristematic cell length was unaffected by nitrogen deficiency, implying that the division and mitotic growth rates were equally impaired. The shorter mature cell length arose from a considerably reduced post-mitotic growth rate (0.033 versus 0.049 h(-1)). But, nitrogen stress did not affect the position where elongation stopped, and increased cell elongation duration. In conclusion, nitrogen deficiency limited leaf growth by increasing the cell cycle duration and decreasing mitotic and post-mitotic elongation rates, delaying cell maturation.

  7. 50 CFR Appendix A to Part 654 - Figures

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ..., DEPARTMENT OF COMMERCE STONE CRAB FISHERY OF THE GULF OF MEXICO Pt. 654, App. A Appendix A to Part 654—Figures Figure 1—Stone Crab Claw Figure 2—Southwest Florida Seasonal Trawl Closure Figure 3—Shrimp/Stone Crab Separation Zones EC03MR91.064 EC03MR91.065 EC03MR91.066...

  8. 50 CFR Appendix A to Part 654 - Figures

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., DEPARTMENT OF COMMERCE STONE CRAB FISHERY OF THE GULF OF MEXICO Pt. 654, App. A Appendix A to Part 654—Figures Figure 1—Stone Crab Claw Figure 2—Southwest Florida Seasonal Trawl Closure Figure 3—Shrimp/Stone Crab Separation Zones EC03MR91.064 EC03MR91.065 EC03MR91.066...

  9. The biphasic interphase-mitotic polarity of cell nuclei induced under DNA replication stress seems to be correlated with Pin2 localization in root meristems of Allium cepa.

    PubMed

    Żabka, Aneta; Trzaskoma, Paweł; Winnicki, Konrad; Polit, Justyna Teresa; Chmielnicka, Agnieszka; Maszewski, Janusz

    2015-02-01

    Long-term treatment of Allium cepa seedlings with low concentration of hydroxyurea (HU) results in a disruption of cell cycle checkpoints, leading root apex meristem (RAM) cells to an abnormal organization of nuclear structures forming interphase (I) and mitotic (M) domains of chromatin at opposite poles of the nucleus. Thus far, both critical cell length and an uneven distribution of cyclin B-like proteins along the nuclear axis have been recognized as essential factors needed to facilitate the formation of biphasic interphase-mitotic (IM) cells. Two new aspects with respect to their emergence are investigated in this study. The first concerns a relationship between the polarity of increasing chromatin condensation (IM orientation) and the acropetal (base→apex) alignment of RAM cell files. The second problem involves the effects of auxin (IAA), on the frequency of IM cells. We provide evidence that there is an association between the advanced M-poles of the IM cell nuclei and the polarized accumulation sites of auxin efflux carriers (PIN2 proteins) and IAA. Furthermore, our observations reveal exclusion regions for PIN2 proteins in the microtubule-rich structures, such as preprophase bands (PPBs) and phragmoplast. The current and previous studies have prompted us to formulate a hypothetical mechanism linking PIN2-mediated unilateral localization of IAA and the induction of bipolar IM cells in HU-treated RAMs of A. cepa.

  10. PARP targeting counteracts gliomagenesis through induction of mitotic catastrophe and aggravation of deficiency in homologous recombination in PTEN-mutant glioma

    PubMed Central

    Majuelos-Melguizo, Jara; Rodríguez, María Isabel; López-Jiménez, Laura; Rodríguez-Vargas, Jose M.; Martí Martín-Consuegra, Juan M.; Serrano-Sáenz, Santiago; Gavard, Julie; Mariano Ruiz de Almodóvar, J; Javier Oliver, F

    2015-01-01

    Glioblastoma multiforme (GBM) is the most common primary brain tumour in adults and one of the most aggressive cancers. PARP-1 is a nuclear protein involved in multiple facets of DNA repair and transcriptional regulation. In this study we dissected the action of PARP inhibition in different GBM cell lines with either functional or mutated PTEN that confers resistance to diverse therapies. In PTEN mutant cells, PARP inhibition induced a severe genomic instability, exacerbated homologous recombination repair (HR) deficiency and down-regulated the Spindle Assembly Checkpoint (SAC) factor BUBR1, leading to mitotic catastrophe (MC). EGFR gene amplification also represents a signature of genetic abnormality in GBM. To more effectively target GBM cells, co-treatment with a PARP inhibitor and an EGFR blocker, erlotinib, resulted in a strong suppression of ERK1/2 activation and in vivo the combined effect elicited a robust reduction in tumour development. In conclusion, PARP inhibition targets PTEN-deficient GBM cells through accentuation of SAC repression and aggravation of HR deficiency, leading to the induction of genomic instability and eventually deriving to mitotic catastrophe (MC); the inhibition of PARP and co-treatment with an inhibitor of pro-survival pathways strongly retarded in vivo gliomagenesis. PMID:25576921

  11. The biphasic interphase-mitotic polarity of cell nuclei induced under DNA replication stress seems to be correlated with Pin2 localization in root meristems of Allium cepa.

    PubMed

    Żabka, Aneta; Trzaskoma, Paweł; Winnicki, Konrad; Polit, Justyna Teresa; Chmielnicka, Agnieszka; Maszewski, Janusz

    2015-02-01

    Long-term treatment of Allium cepa seedlings with low concentration of hydroxyurea (HU) results in a disruption of cell cycle checkpoints, leading root apex meristem (RAM) cells to an abnormal organization of nuclear structures forming interphase (I) and mitotic (M) domains of chromatin at opposite poles of the nucleus. Thus far, both critical cell length and an uneven distribution of cyclin B-like proteins along the nuclear axis have been recognized as essential factors needed to facilitate the formation of biphasic interphase-mitotic (IM) cells. Two new aspects with respect to their emergence are investigated in this study. The first concerns a relationship between the polarity of increasing chromatin condensation (IM orientation) and the acropetal (base→apex) alignment of RAM cell files. The second problem involves the effects of auxin (IAA), on the frequency of IM cells. We provide evidence that there is an association between the advanced M-poles of the IM cell nuclei and the polarized accumulation sites of auxin efflux carriers (PIN2 proteins) and IAA. Furthermore, our observations reveal exclusion regions for PIN2 proteins in the microtubule-rich structures, such as preprophase bands (PPBs) and phragmoplast. The current and previous studies have prompted us to formulate a hypothetical mechanism linking PIN2-mediated unilateral localization of IAA and the induction of bipolar IM cells in HU-treated RAMs of A. cepa. PMID:25462968

  12. Angular Figures Constrain the Perpendicular Bias in Children's Line Copying

    ERIC Educational Resources Information Center

    Davis, A.; Bruyn, B.D.; Boyles, S.

    2005-01-01

    When young children copy a vertical line that protrudes from the midpoint of a pre-drawn oblique baseline, they tend to perpendicularise this line. We measured this bias for standard figures and for symmetrical angular figures. The 5- and 6-year-old participants produced the expected bias for the standard figures. However, these same children…

  13. Poetry and the Teaching of Figurative Language Skills.

    ERIC Educational Resources Information Center

    Bush, Harold K., Jr.

    Many teachers note the importance of student ability to analyze and understand intricate uses of figurative language in reading. Research in recent years has focused on the prevalence of figures of speech in textbooks and other reading, suggesting that the fostering of figurative language skills should become a more common feature of language…

  14. Aurora kinase-induced phosphorylation excludes transcription factor RUNX from the chromatin to facilitate proper mitotic progression.

    PubMed

    Chuang, Linda Shyue Huey; Khor, Jian Ming; Lai, Soak Kuan; Garg, Shubham; Krishnan, Vaidehi; Koh, Cheng-Gee; Lee, Sang Hyun; Ito, Yoshiaki

    2016-06-01

    The Runt-related transcription factors (RUNX) are master regulators of development and major players in tumorigenesis. Interestingly, unlike most transcription factors, RUNX proteins are detected on the mitotic chromatin and apparatus, suggesting that they are functionally active in mitosis. Here, we identify key sites of RUNX phosphorylation in mitosis. We show that the phosphorylation of threonine 173 (T173) residue within the Runt domain of RUNX3 disrupts RUNX DNA binding activity during mitotic entry to facilitate the recruitment of RUNX proteins to mitotic structures. Moreover, knockdown of RUNX3 delays mitotic entry. RUNX3 phosphorylation is therefore a regulatory mechanism for mitotic entry. Cancer-associated mutations of RUNX3 T173 and its equivalent in RUNX1 further corroborate the role of RUNX phosphorylation in regulating proper mitotic progression and genomic integrity. PMID:27217562

  15. Chromosomal abnormalities in human sperm

    SciTech Connect

    Martin, R.H.

    1985-01-01

    The ability to analyze human sperm chromosome complements after penetration of zona pellucida-free hamster eggs provides the first opportunity to study the frequency and type of chromosomal abnormalities in human gametes. Two large-scale studies have provided information on normal men. We have studied 1,426 sperm complements from 45 normal men and found an abnormality rate of 8.9%. Brandriff et al. (5) found 8.1% abnormal complements in 909 sperm from 4 men. The distribution of numerical and structural abnormalities was markedly dissimilar in the 2 studies. The frequency of aneuploidy was 5% in our sample and only 1.6% in Brandriff's, perhaps reflecting individual variability among donors. The frequency of 24,YY sperm was low: 0/1,426 and 1/909. This suggests that the estimates of nondisjunction based on fluorescent Y body data (1% to 5%) are not accurate. We have also studied men at increased risk of sperm chromosomal abnormalities. The frequency of chromosomally unbalanced sperm in 6 men heterozygous for structural abnormalities varied dramatically: 77% for t11;22, 32% for t6;14, 19% for t5;18, 13% for t14;21, and 0% for inv 3 and 7. We have also studied 13 cancer patients before and after radiotherapy and demonstrated a significant dose-dependent increase of sperm chromosome abnormalities (numerical and structural) 36 months after radiation treatment.

  16. Inhibitory factors associated with anaphase-promoting complex/cylosome in mitotic checkpoint

    PubMed Central

    Braunstein, Ilana; Miniowitz, Shirly; Moshe, Yakir; Hershko, Avram

    2007-01-01

    The mitotic (or spindle assembly) checkpoint system ensures accurate chromosome segregation by preventing anaphase initiation until all chromosomes are correctly attached to the mitotic spindle. It affects the activity of the anaphase-promoting complex/cyclosome (APC/C), a ubiquitin ligase that targets inhibitors of anaphase initiation for degradation. The mechanisms by which this system regulates APC/C remain obscure. Some models propose that the system promotes sequestration of the APC/C activator Cdc20 by binding to the checkpoint proteins Mad2 and BubR1. A different model suggests that a mitotic checkpoint complex (MCC) composed of BubR1, Bub3, Cdc20, and Mad2 inhibits APC/C in mitotic checkpoint [Sudakin V, Chan GKT, Yen TJ (2001) J Cell Biol 154:925–936]. We examined this problem by using extracts from nocodazole-arrested cells that reproduce some downstream events of the mitotic checkpoint system, such as lag kinetics of the degradation of APC/C substrate. Incubation of extracts with adenosine-5′-(γ-thio)triphosphate (ATP[γS]) stabilized the checkpoint-arrested state, apparently by stable thiophosphorylation of some proteins. By immunoprecipitation of APC/C from stably checkpoint-arrested extracts, followed by elution with increased salt concentration, we isolated inhibitory factors associated with APC/C. A part of the inhibitory material consists of Cdc20 associated with BubR1 and Mad2, and is thus similar to MCC. Contrary to the original MCC hypothesis, we find that MCC disassembles upon exit from the mitotic checkpoint. Thus, the requirement of the mitotic checkpoint system for the binding of Mad2 and BubR1 to Cdc20 may be for the assembly of the inhibitory complex rather than for Cdc20 sequestration. PMID:17360335

  17. Continued Stabilization of the Nuclear Higher-Order Structure of Post-Mitotic Neurons In Vivo

    PubMed Central

    Alva-Medina, Janeth; Maya-Mendoza, Apolinar; Dent, Myrna A. R.; Aranda-Anzaldo, Armando

    2011-01-01

    Background Cellular terminal differentiation (TD) correlates with a permanent exit from the cell cycle and so TD cells become stably post-mitotic. However, TD cells express the molecular machinery necessary for cell proliferation that can be reactivated by experimental manipulation, yet it has not been reported the stable proliferation of any type of reactivated TD cells. Neurons become post-mitotic after leaving the ventricular zone. When neurons are forced to reenter the cell cycle they invariably undergo cell death. Wider evidence indicates that the post-mitotic state cannot solely depend on gene products acting in trans, otherwise mutations in the corresponding genes may lead to reentry and completion of the cell cycle in TD cells, but this has not been observed. In the interphase, nuclear DNA of metazoan cells is organized in supercoiled loops anchored to a nuclear nuclear matrix (NM). The DNA-NM interactions define a higher-order structure in the cell nucleus (NHOS). We have previously compared the NHOS of aged rat hepatocytes with that of early post-mitotic rat neurons and our results indicated that a very stable NHOS is a common feature of both senescent and post-mitotic cells in vivo. Principal Findings In the present work we compared the NHOS in rat neurons from different post-natal ages. Our results show that the trend towards further stabilization of the NHOS in neurons continues throughout post-natal life. This phenomenon occurs in absence of overt changes in the post-mitotic state and transcriptional activity of neurons, suggesting that it is independent of functional constraints. Conclusions Apparently the continued stabilization of the NHOS as a function of time is basically determined by thermodynamic and structural constraints. We discuss how the resulting highly stable NHOS of neurons may be the structural, non-genetic basis of their permanent and irreversible post-mitotic state. PMID:21731716

  18. Bcl-xL controls a switch between cell death modes during mitotic arrest

    PubMed Central

    Bah, N; Maillet, L; Ryan, J; Dubreil, S; Gautier, F; Letai, A; Juin, P; Barillé-Nion, S

    2014-01-01

    Antimitotic agents such as microtubule inhibitors (paclitaxel) are widely used in cancer therapy while new agents blocking mitosis onset are currently in development. All these agents impose a prolonged mitotic arrest in cancer cells that relies on sustained activation of the spindle assembly checkpoint and may lead to subsequent cell death by incompletely understood molecular events. We have investigated the role played by anti-apoptotic Bcl-2 family members in the fate of mitotically arrested mammary tumor cells treated with paclitaxel, or depleted in Cdc20, the activator of the anaphase promoting complex. Under these conditions, a weak and delayed mitotic cell death occurs that is caspase- and Bax/Bak-independent. Moreover, BH3 profiling assays indicate that viable cells during mitotic arrest are primed to die by apoptosis and that Bcl-xL is required to maintain mitochondrial integrity. Consistently, Bcl-xL depletion, or treatment with its inhibitor ABT-737 (but not with the specific Bcl-2 inhibitor ABT-199), during mitotic arrest converts cell response to antimitotics to efficient caspase and Bax-dependent apoptosis. Apoptotic priming under conditions of mitotic arrest relies, at least in part, on the phosphorylation on serine 62 of Bcl-xL, which modulates its interaction with Bax and its sensitivity to ABT-737. The phospho-mimetic S62D-Bcl-xL mutant is indeed less efficient than the corresponding phospho-deficient S62A-Bcl-xL mutant in sequestrating Bax and in protecting cancer cells from mitotic cell death or yeast cells from Bax-induced growth inhibition. Our results provide a rationale for combining Bcl-xL targeting to antimitotic agents to improve clinical efficacy of antimitotic strategy in cancer therapy. PMID:24922075

  19. Radmis, a Novel Mitotic Spindle Protein that Functions in Cell Division of Neural Progenitors

    PubMed Central

    Yumoto, Takahito; Nakadate, Kazuhiko; Nakamura, Yuki; Sugitani, Yoshinobu; Sugitani-Yoshida, Reiko; Ueda, Shuichi; Sakakibara, Shin-ichi

    2013-01-01

    Developmental dynamics of neural stem/progenitor cells (NSPCs) are crucial for embryonic and adult neurogenesis, but its regulatory factors are not fully understood. By differential subtractive screening with NSPCs versus their differentiated progenies, we identified the radmis (radial fiber and mitotic spindle)/ckap2l gene, a novel microtubule-associated protein (MAP) enriched in NSPCs. Radmis is a putative substrate for the E3-ubiquitin ligase, anaphase promoting complex/cyclosome (APC/C), and is degraded via the KEN box. Radmis was highly expressed in regions of active neurogenesis throughout life, and its distribution was dynamically regulated during NSPC division. In embryonic and perinatal brains, radmis localized to bipolar mitotic spindles and radial fibers (basal processes) of dividing NSPCs. As central nervous system development proceeded, radmis expression was lost in most brain regions, except for several neurogenic regions. In adult brain, radmis expression persisted in the mitotic spindles of both slowly-dividing stem cells and rapid amplifying progenitors. Overexpression of radmis in vitro induced hyper-stabilization of microtubules, severe defects in mitotic spindle formation, and mitotic arrest. In vivo gain-of-function using in utero electroporation revealed that radmis directed a reduction in NSPC proliferation and a concomitant increase in cell cycle exit, causing a reduction in the Tbr2-positive basal progenitor population and shrinkage of the embryonic subventricular zone. Besides, radmis loss-of-function by shRNAs induced the multipolar mitotic spindle structure, accompanied with the catastrophe of chromosome segregation including the long chromosome bridge between two separating daughter nuclei. These findings uncover the indispensable role of radmis in mitotic spindle formation and cell-cycle progression of NSPCs. PMID:24260314

  20. Induction of Aneuploidy, Centrosome Abnormality, Multipolar Spindle, and Multipolar Division in Cultured Mammalian Cells Exposed to an Arsenic Metabolite, Dimethylarsinate.

    PubMed

    Ochi, Takafumi

    2016-01-01

    Toxicological studies of arsenic compounds were conducted in cultured mammalian cells to investigate the effects of glutathione (GSH) depletion. Dimethylarsinate DMA(V) was not cytotoxic in cells depleted of GSH, but was found to be cytotoxic when GSH was present outside the cells. The results suggested that a reactive form of DMA(V) was generated through interaction with GSH. Dimethylarsine iodide DMI(III) was used as a model compound of DMA(III), and the biological effects were investigated. DMI(III) was about 10000 times more toxic to the cells than DMA(V). Chromosome structural aberrations and numerical changes, such as aneuploidy, were induced by DMI(III). DMA(V) induced multiple foci of the centrosome protein, γ-tubulin, which were colocalized with multipolar spindles in mitotic cells. The multiple foci coalesced into a single dot on disruption of the microtubules (MT). However, reorganization of the MT caused multiple foci of γ-tubulin, suggesting that the induction of centrosome abnormalities by DMA(V) required intact MT. Inhibition of the MT-dependent motor, kinesin, prevented formation of multiple foci of γ-tubulin, which pointed to the involvement of the MT-dependent mitotic motor, kinesin, in the maintenance of centrosome abnormalities. DMI(III) caused abnormal cytokinesis (multipolar division). In addition, DMI(III) caused morphological transformation in Syrian hamster embryo cells. Consideration of the overall process following the centrosome abnormalities caused by DMA(V) suggested a mode of cytotoxicity in which the mitotic centrosome is a critical target. PMID:27252065

  1. Figure Control of Lightweight Optical Structures

    NASA Technical Reports Server (NTRS)

    Main, John A.; Song, Haiping

    2005-01-01

    The goal of this paper is to demonstrate the use of fuzzy logic controllers in modifying the figure of a piezoceramic bimorph mirror. Non-contact electron actuation technology is used to actively control a bimorph mirror comprised two PZT-5H wafers by varying the electron flux and electron voltages. Due to electron blooming generated by the electron flux, it is difficult to develop an accurate control model for the bimorph mirror through theoretical analysis alone. The non-contact shape control system with electron flux blooming can be approximately described with a heuristic model based on experimental data. Two fuzzy logic feedback controllers are developed to control the shape of the bimorph mirror according to heuristic fuzzy inference rules generated from previous experimental results. Validation of the proposed fuzzy logic controllers is also discussed.

  2. Internal Structure and Figures of Binary Asteroids

    NASA Astrophysics Data System (ADS)

    Hestroffer, Daniel

    2005-07-01

    The goal of this proposal is to obtain very important information on the internal structure of a number of asteroids, and insight on the gravitational reaccumulation-process after a catastrophic disruptive collision. High resolutions observations with the HST/FGS interferometer are proposed to obtain high precision data for the topographic shape and size of a number of selected asteroids. Here we focus on objects with satellites, hence with known masses, so that the bulk density and porosity will be derived in the most accurate manner. This will yield plausible estimates on the internal properties of the objects, test wether they are close or not to figures of equilibrium {in terms of shape and adimensional rotational frequency}, and provide estimates of their relative density. The HST/FGS in interferometric mode is an ideal facility to carry out this program.

  3. Somatic mosaicism of expanded CAG repeats in brains of patients with dentatorubral-pallidoluysian atrophy: cellular population-dependent dynamics of mitotic instability.

    PubMed Central

    Takano, H.; Onodera, O.; Takahashi, H.; Igarashi, S.; Yamada, M.; Oyake, M.; Ikeuchi, T.; Koide, R.; Tanaka, H.; Iwabuchi, K.; Tsuji, S.

    1996-01-01

    Dentatorubral-pallidoluysian atrophy (DRPLA) is an autosomal dominant neurodegenerative disease caused by unstable expansion of a CAG repeat in the DRPLA gene. We performed detailed quantitative analysis of the size and the size distribution (range) of the expanded CAG repeats in various regions of the CNS of eight autopsied patients with DRPLA. Expanded alleles (AE) showed considerable variations in size, as well as in range, depending on the region of the CNS, whereas normal alleles did not show such variations, which indicates the occurrence of somatic mosaicism of AE in the CNS. The AE in the cerebellar cortex were consistently smaller by two to five repeat units than those in the cerebellar white matter. Moreover, the AE in the cerebral cortex were smaller by one to four repeat units than those in the cerebral white matter. These results suggest that the smaller AE in the cerebellar and cerebral cortices represent those of neuronal cells. The ranges of the AE in the cerebral cortex, cerebral white matter, and cerebellar white matter showed considerable variation ranging from 9 to 23 repeat units, whereas those in the cerebellar cortex showed little variance and were approximately 7 repeat units. The ranges of the AE in the cerebral cortex, cerebral white matter, and cerebellar white matter were much broader in patients with higher ages at death than they were in patients with lower ages at death, raising the possibility that the range of AE increases with time, as the result of mitotic instability of AE. Images Figure 1 Figure 3 Figure 4 Figure 6 PMID:8651298

  4. Potential Link between the NIMA Mitotic Kinase and Nuclear Membrane Fission during Mitotic Exit in Aspergillus nidulans

    PubMed Central

    Davies, Jonathan R.; Osmani, Aysha H.; De Souza, Colin P. C.; Bachewich, Catherine; Osmani, Stephen A.

    2004-01-01

    We have isolated TINC as a NIMA-interacting protein by using the yeast two-hybrid system and have confirmed that TINC interacts with NIMA in Aspergillus nidulans. The TINC-NIMA interaction is stabilized in the absence of phosphatase inhibitors and in the presence of kinase-inactive NIMA, suggesting that the interaction is enhanced when NIMA is not fully activated. TINC is a cytoplasmic protein. TINC homologues and a TINC-like protein (A. nidulans HETC) are conserved in other filamentous fungi. Neither deletion of tinC nor deletion of both tinC and A. nidulans hetC is lethal, but deletion of tinC does produce cold sensitivity as well as osmotic sensitivity. Expression of an amino-terminal-truncated form of TINC (ΔN-TINC) inhibits colony growth in Aspergillus and localizes to membrane-like structures within the cell. Examination of cell cycle progression in these cells reveals that they progress through multiple defective mitoses. Many cells contain large polyploid single nuclei, while some appear to have separated masses of DNA. Examination of the nuclear envelopes of cells containing more than one DNA mass reveals that both DNA masses are contained within a single nuclear envelope, indicating that nuclear membrane fission is defective. The ability of these cells to separate DNA segregation from nuclear membrane fission suggests that this coordination is normally a regulated process in A. nidulans. Additional experiments demonstrate that expression of ΔN-TINC results in premature NIMA disappearance in mitotic samples. We propose that TINC's interaction with NIMA and the cell cycle defects produced by ΔN-TINC expression suggest possible roles for TINC and NIMA during nuclear membrane fission. PMID:15590818

  5. Potential link between the NIMA mitotic kinase and nuclear membrane fission during mitotic exit in Aspergillus nidulans.

    PubMed

    Davies, Jonathan R; Osmani, Aysha H; De Souza, Colin P C; Bachewich, Catherine; Osmani, Stephen A

    2004-12-01

    We have isolated TINC as a NIMA-interacting protein by using the yeast two-hybrid system and have confirmed that TINC interacts with NIMA in Aspergillus nidulans. The TINC-NIMA interaction is stabilized in the absence of phosphatase inhibitors and in the presence of kinase-inactive NIMA, suggesting that the interaction is enhanced when NIMA is not fully activated. TINC is a cytoplasmic protein. TINC homologues and a TINC-like protein (A. nidulans HETC) are conserved in other filamentous fungi. Neither deletion of tinC nor deletion of both tinC and A. nidulans hetC is lethal, but deletion of tinC does produce cold sensitivity as well as osmotic sensitivity. Expression of an amino-terminal-truncated form of TINC (DeltaN-TINC) inhibits colony growth in Aspergillus and localizes to membrane-like structures within the cell. Examination of cell cycle progression in these cells reveals that they progress through multiple defective mitoses. Many cells contain large polyploid single nuclei, while some appear to have separated masses of DNA. Examination of the nuclear envelopes of cells containing more than one DNA mass reveals that both DNA masses are contained within a single nuclear envelope, indicating that nuclear membrane fission is defective. The ability of these cells to separate DNA segregation from nuclear membrane fission suggests that this coordination is normally a regulated process in A. nidulans. Additional experiments demonstrate that expression of DeltaN-TINC results in premature NIMA disappearance in mitotic samples. We propose that TINC's interaction with NIMA and the cell cycle defects produced by DeltaN-TINC expression suggest possible roles for TINC and NIMA during nuclear membrane fission. PMID:15590818

  6. Hyperactive mTOR pathway promotes lymphoproliferation and abnormal differentiation in autoimmune lymphoproliferative syndrome.

    PubMed

    Völkl, Simon; Rensing-Ehl, Anne; Allgäuer, Andrea; Schreiner, Elisabeth; Lorenz, Myriam Ricarda; Rohr, Jan; Klemann, Christian; Fuchs, Ilka; Schuster, Volker; von Bueren, André O; Naumann-Bartsch, Nora; Gambineri, Eleonora; Siepermann, Kathrin; Kobbe, Robin; Nathrath, Michaela; Arkwright, Peter D; Miano, Maurizio; Stachel, Klaus-Daniel; Metzler, Markus; Schwarz, Klaus; Kremer, Anita N; Speckmann, Carsten; Ehl, Stephan; Mackensen, Andreas

    2016-07-14

    Autoimmune lymphoproliferative syndrome (ALPS) is a human disorder characterized by defective Fas signaling, resulting in chronic benign lymphoproliferation and accumulation of TCRαβ(+) CD4(-) CD8(-) double-negative T (DNT) cells. Although their phenotype resembles that of terminally differentiated or exhausted T cells, lack of KLRG1, high eomesodermin, and marginal T-bet expression point instead to a long-lived memory state with potent proliferative capacity. Here we show that despite their terminally differentiated phenotype, human ALPS DNT cells exhibit substantial mitotic activity in vivo. Notably, hyperproliferation of ALPS DNT cells is associated with increased basal and activation-induced phosphorylation of serine-threonine kinases Akt and mechanistic target of rapamycin (mTOR). The mTOR inhibitor rapamycin abrogated survival and proliferation of ALPS DNT cells, but not of CD4(+) or CD8(+) T cells in vitro. In vivo, mTOR inhibition reduced proliferation and abnormal differentiation by DNT cells. Importantly, increased mitotic activity and hyperactive mTOR signaling was also observed in recently defined CD4(+) or CD8(+) precursor DNT cells, and mTOR inhibition specifically reduced these cells in vivo, indicating abnormal programming of Fas-deficient T cells before the DNT stage. Thus, our results identify the mTOR pathway as a major regulator of lymphoproliferation and aberrant differentiation in ALPS.

  7. Stimulatory Effects of Gamma Irradiation on Phytochemical Properties, Mitotic Behaviour, and Nutritional Composition of Sainfoin (Onobrychis viciifolia Scop.)

    PubMed Central

    Mat Taha, Rosna; Lay, Ma Ma; Khalili, Mahsa

    2014-01-01

    Sainfoin (Onobrychis viciifolia Scop. Syn. Onobrychis sativa L.) is a bloat-safe forage crop with high levels of tannins, which is renowned for its medicinal qualities in grazing animals. Mutagenesis technique was applied to investigate the influence of gamma irradiation at 30, 60, 90, and 120 Gy on mitotic behavior, in vitro growth factors, phytochemical and nutritional constituents of sainfoin. Although a percentage of plant necrosis and non-growing seed were enhanced by irradiation increment, the germination speed was significantly decreased. It was observed that gamma irradiated seeds had higher value of crude protein and dry matter digestibility compared to control seeds. Toxicity of copper was reduced in sainfoin irradiated seeds at different doses of gamma rays. Anthocyanin content also decreased in inverse proportion to irradiation intensity. Accumulation of phenolic and flavonoid compounds was enhanced by gamma irradiation exposure in leaf cells. HPLC profiles differed in peak areas of the two important alkaloids, Berberine and Sanguinarine, in 120 Gy irradiated seeds compared to control seeds. There were positive correlations between irradiation dose and some abnormality divisions such as laggard chromosome, micronucleus, binucleated cells, chromosome bridge, and cytomixis. In reality, radiocytological evaluation was proven to be essential in deducing the effectiveness of gamma irradiation to induce somaclonal variation in sainfoin. PMID:25147870

  8. Atoh1 governs the migration of post-mitotic neurons that shape respiratory effectiveness at birth and chemoresponsiveness in adulthood

    PubMed Central

    Huang, Wei-Hsiang; Tupal, Srinivasan; Huang, Teng-Wei; Ward, Christopher S.; Neul, Jeffery L.; Klisch, Tiemo J.; Gray, Paul A.; Zoghbi, Huda Y.

    2012-01-01

    SUMMARY Hindbrain neuronal networks serving respiratory, proprioceptive, and arousal functions share a developmental requirement for the bHLH transcription factor Atoh1. Loss of Atoh1 in mice results in respiratory failure and neonatal lethality; however, the neuronal identity and mechanism by which Atoh1-dependent cells sustain newborn breathing remains unknown. We uncovered that selective loss of Atoh1 from the post-mitotic retrotrapezoid nucleus (RTN) neurons results in severely impaired inspiratory rhythm and pronounced neonatal death. Mice that escape neonatal death develop abnormal chemoresponsiveness as adults. Interestingly, the expression of Atoh1 in the RTN neurons is not required for their specification or maintenance, but is important for their proper localization and to establish essential connections with the preBötzinger Complex (preBötC). These results provide insights into the genetic regulation of neonatal breathing and shed light on the labile sites that might contribute to sudden death in newborn infants and altered chemoresponsiveness in adults. PMID:22958821

  9. hSNF5/INI1 inactivation is mainly associated with homozygous deletions and mitotic recombinations in rhabdoid tumors.

    PubMed

    Rousseau-Merck, M F; Versteege, I; Legrand, I; Couturier, J; Mairal, A; Delattre, O; Aurias, A

    1999-07-01

    The chromatin-remodeling hSNF5/INI1 gene has recently been shown to act as a tumor suppressor gene in rhabdoid tumors (RTs). In an attempt to further characterize the main chromosomal mechanisms involved in hSNF5/INI1 inactivation in RTs, we report here the molecular cytogenetic data obtained in 12 cell lines harboring hSNF5/INI1 mutations and/or deletions in relation to the molecular genetic analysis using polymorphic markers extended to both extremities of chromosome 22q. On the whole, mitotic recombination occurring in the proximal part of chromosome 22q, as demonstrated in five cases, and nondisjunction/duplication, highly suspected in two cases (processes leading respectively to partial or complete isodisomy), appear to be major mechanisms associated with hSNF5/INI1 inactivation. Such isodisomy accompanies each of the RTs exhibiting two cytogenetically normal chromosomes 22. This results in homozygosity for the mutation at the hSNF5/INI1 locus. An alternate mechanism accounting for hSNF5/INI1 inactivation observed in these tumors is homozygous deletion in the rhabdoid consensus region. This was observed in each of the four tumors carrying a chromosome 22q abnormality and, in particular, in the three tumors with chromosomal translocations. Only one case of our series illustrates the mutation/deletion classical model proposed for the double-hit inactivation of a tumor suppressor gene. PMID:10397258

  10. Literal and figurative interpretations are computed in equal time.

    PubMed

    McElree, B; Nordlie, J

    1999-09-01

    The time courses for constructing literal and figurative interpretations of simple propositions were measured with the response signal, speed-accuracy tradeoff procedure. No differences were found in comprehension speed for literal and figurative strings in a task that required judging whether a string of words was meaningful. Likewise, no differences were found in processing speed for nonsense and figurative strings in a task that required judging whether a string of words was literally true. Figurative strings were less likely to be judged meaningful than were literal strings and less likely to be rejected as literally true than were nonsense strings. The absence of time-course differences is inconsistent with approaches to figurative processing that contend that a figurative interpretation is computed after an anomalous literal interpretation. The time-course profiles suggest that literal and figurative interpretations are computed in equal time but that the meaning of the latter is less constrained than that of the former. PMID:12198788

  11. A figure control sensor for the Large Deployable Reflector (LDR)

    NASA Technical Reports Server (NTRS)

    Bartman, R.; Dubovitsky, S.

    1988-01-01

    A sensing and control system is required to maintain high optical figure quality in a segmented reflector. Upon detecting a deviation of the segmented surface from its ideal form, the system drives segment mounted actuators to realign the individual segments and thereby return the surface to its intended figure. When the reflector is in use, a set of figure sensors will determine positions of a number of points on the back surface of each of the reflector's segments, each sensor being assigned to a single point. By measuring the positional deviations of these points from previously established nominal values, the figure sensors provide the control system with the information required to maintain the reflector's optical figure. The optical lever, multiple wavelength interferometer, and electronic capacitive sensor, the most promising technologies for the development of the figure sensor, are illustrated. It is concluded that to select a particular implementation of the figure sensors, performance requirement will be refined and relevant technologies investigated further.

  12. A Computer Graphics Human Figure Application Of Biostereometrics

    NASA Astrophysics Data System (ADS)

    Fetter, William A.

    1980-07-01

    A study of improved computer graphic representation of the human figure is being conducted under a National Science Foundation grant. Special emphasis is given biostereometrics as a primary data base from which applications requiring a variety of levels of detail may be prepared. For example, a human figure represented by a single point can be very useful in overview plots of a population. A crude ten point figure can be adequate for queuing theory studies and simulated movement of groups. A one hundred point figure can usefully be animated to achieve different overall body activities including male and female figures. A one thousand point figure si-milarly animated, begins to be useful in anthropometrics and kinesiology gross body movements. Extrapolations of this order-of-magnitude approach ultimately should achieve very complex data bases and a program which automatically selects the correct level of detail for the task at hand. See Summary Figure 1.

  13. Ki-67 acts as a biological surfactant to disperse mitotic chromosomes.

    PubMed

    Cuylen, Sara; Blaukopf, Claudia; Politi, Antonio Z; Müller-Reichert, Thomas; Neumann, Beate; Poser, Ina; Ellenberg, Jan; Hyman, Anthony A; Gerlich, Daniel W

    2016-06-29

    Eukaryotic genomes are partitioned into chromosomes that form compact and spatially well-separated mechanical bodies during mitosis. This enables chromosomes to move independently of each other for segregation of precisely one copy of the genome to each of the nascent daughter cells. Despite insights into the spatial organization of mitotic chromosomes and the discovery of proteins at the chromosome surface, the molecular and biophysical bases of mitotic chromosome structural individuality have remained unclear. Here we report that the proliferation marker protein Ki-67 (encoded by the MKI67 gene), a component of the mitotic chromosome periphery, prevents chromosomes from collapsing into a single chromatin mass after nuclear envelope disassembly, thus enabling independent chromosome motility and efficient interactions with the mitotic spindle. The chromosome separation function of human Ki-67 is not confined within a specific protein domain, but correlates with size and net charge of truncation mutants that apparently lack secondary structure. This suggests that Ki-67 forms a steric and electrostatic charge barrier, similar to surface-active agents (surfactants) that disperse particles or phase-separated liquid droplets in solvents. Fluorescence correlation spectroscopy showed a high surface density of Ki-67 and dual-colour labelling of both protein termini revealed an extended molecular conformation, indicating brush-like arrangements that are characteristic of polymeric surfactants. Our study thus elucidates a biomechanical role of the mitotic chromosome periphery in mammalian cells and suggests that natural proteins can function as surfactants in intracellular compartmentalization.

  14. Studies on the control of mitotic activity in excised roots. I. The experimental system.

    PubMed

    WILSON, G B; MORRISON, J H; KNOBLOCH, N

    1959-05-25

    The mitotic characteristics of excised roots of the garden pea, Pisum sativum, have been studied under conditions of controlled nutrition. The excised root system was tested with regard to its ability to respond, mitotically, to various carbon sources. Sucrose, glucose, fructose, and DL-glyceraldehyde were found to support mitotic activity in excised roots, galactose and 2-deoxy-D-glucose were toxic, and mannose ineffective. Initiation of mitotic activity in the presence of glucose was inhibited by the respiratory poisons, KCN and malonic acid, the uncoupling agent, 2,4-dinitrophenol, but was not notably affected by the protein synthesis inhibitor, chloramphenicol. The glucose-induced response in mitotic activity was not affected by the carcinogen, urethan, and indeed, there is some evidence that the response was actually enhanced. The fact that KCN, malonic acid, and probably 2,4-dinitrophenol, in suitable concentrations inhibit the onset of cell division suggests that some level of operation of the Krebs' cycle is essential for commission of cells into mitosis. Likewise, failure to inhibit cells in the process of active mitosis by KCN and malonic acid is not inconsistent with the idea that there is a shift from reliance on aerobic to anaerobic respiration between antephase and active mitosis.

  15. Sources and Structures of Mitotic Crossovers That Arise When BLM Helicase Is Absent in Drosophila

    PubMed Central

    LaFave, Matthew C.; Andersen, Sabrina L.; Stoffregen, Eric P.; Holsclaw, Julie K.; Kohl, Kathryn P.; Overton, Lewis J.; Sekelsky, Jeff

    2014-01-01

    The Bloom syndrome helicase, BLM, has numerous functions that prevent mitotic crossovers. We used unique features of Drosophila melanogaster to investigate origins and properties of mitotic crossovers that occur when BLM is absent. Induction of lesions that block replication forks increased crossover frequencies, consistent with functions for BLM in responding to fork blockage. In contrast, treatment with hydroxyurea, which stalls forks, did not elevate crossovers, even though mutants lacking BLM are sensitive to killing by this agent. To learn about sources of spontaneous recombination, we mapped mitotic crossovers in mutants lacking BLM. In the male germline, irradiation-induced crossovers were distributed randomly across the euchromatin, but spontaneous crossovers were nonrandom. We suggest that regions of the genome with a high frequency of mitotic crossovers may be analogous to common fragile sites in the human genome. Interestingly, in the male germline there is a paucity of crossovers in the interval that spans the pericentric heterochromatin, but in the female germline this interval is more prone to crossing over. Finally, our system allowed us to recover pairs of reciprocal crossover chromosomes. Sequencing of these revealed the existence of gene conversion tracts and did not provide any evidence for mutations associated with crossovers. These findings provide important new insights into sources and structures of mitotic crossovers and functions of BLM helicase. PMID:24172129

  16. The effect of magnesium on mitotic spindle formation in Schizosaccharomyces pombe.

    PubMed

    Uz, Gulsen; Sarikaya, Aysegul Topal

    2016-01-01

    Magnesium (Mg2+), an essential ion for cells and biological systems, is involved in a variety of cellular processes, including the formation and breakdown of microtubules. The results of a previous investigation suggested that as cells grow the intracellular Mg2+ concentration falls, thereby stimulating formation of the mitotic spindle. In the present work, we used a Mg2+-deficient Schizosaccharomyces pombe strain GA2, in which two essential membrane Mg2+ transporter genes (homologs of ALR1 and ALR2 in Saccharomyces cerevisae) were deleted, and its parental strain Sp292, to examine the extent to which low Mg2+ concentrations can affect mitotic spindle formation. The two S. pombe strains were transformed with a plasmid carrying a GFP-α2-tubulin construct to fluorescently label microtubules. Using the free Mg2+-specific fluorescent probe mag-fura-2, we confirmed that intracellular free Mg2+ levels were lower in GA2 than in the parental strain. Defects in interphase microtubule organization, a lower percentage of mitotic spindle formation and a reduced mitotic index were also observed in the GA2 strain. Although there was interphase microtubule polymerization, the lower level of mitotic spindle formation in the Mg2+-deficient strain suggested a greater requirement for Mg2+ in this phenomenon than previously thought.

  17. Aurora B prevents delayed DNA replication and premature mitotic exit by repressing p21Cip1

    PubMed Central

    Trakala, Marianna; Fernández-Miranda, Gonzalo; Pérez de Castro, Ignacio; Heeschen, Christopher; Malumbres, Marcos

    2013-01-01

    Aurora kinase B is a critical component of the chromosomal passenger complex, which is involved in the regulation of microtubule-kinetochore attachments and cytokinesis. By using conditional knockout cells and chemical inhibition, we show here that inactivation of Aurora B results in delayed G1/S transition and premature mitotic exit. Aurora B deficiency results in delayed DNA replication in cultured fibroblasts as well as liver cells after hepatectomy. This is accompanied by increased transcription of the cell cycle inhibitor p21Cip1. Lack of Aurora B does not prevent mitotic entry but results in a premature exit from prometaphase in the presence of increased p21Cip1-Cdk1 inactive complexes. Aurora B-null cells display reduced degradation of cyclin B1, suggesting the presence of phenomenon known as adaptation to the mitotic checkpoint, previously described in yeast. Elimination of p21Cip1 rescues Cdk1 activity and prevents premature mitotic exit in Aurora B-deficient cells. These results suggest that Aurora B represses p21Cip1, preventing delayed DNA replication, Cdk inhibition and premature mitotic exit. The upregulation of p21Cip1 observed after inhibition of Aurora B may have important implications in cell cycle progression, tetraploidy, senescence or cancer therapy. PMID:23428904

  18. Plk1-dependent recruitment of gamma-tubulin complexes to mitotic centrosomes involves multiple PCM components.

    PubMed

    Haren, Laurence; Stearns, Tim; Lüders, Jens

    2009-01-01

    The nucleation of microtubules requires protein complexes containing gamma-tubulin, which are present in the cytoplasm and associate with the centrosome and with the mitotic spindle. We have previously shown that these interactions require the gamma-tubulin targeting factor GCP-WD/NEDD1, which has an essential role in spindle formation. The recruitment of additional gamma-tubulin to the centrosomes occurs during centrosome maturation at the G2/M transition and is regulated by the mitotic kinase Plk1. However, the molecular details of this important pathway are unknown and a Plk1 substrate that controls gamma-tubulin recruitment has not been identified. Here we show that Plk1 associates with GCP-WD in mitosis and Plk1 activity contributes to phosphorylation of GCP-WD. Plk1 depletion or inhibition prevents accumulation of GCP-WD at mitotic centrosomes, but GCP-WD mutants that are defective in Plk1-binding and -phosphorylation still accumulate at mitotic centrosomes and recruit gamma-tubulin. Moreover, Plk1 also controls the recruitment of other PCM proteins implicated in centrosomal gamma-tubulin attachment (Cep192/hSPD2, pericentrin, Cep215/Cdk5Rap2). Our results support a model in which Plk1-dependent recruitment of gamma-tubulin to mitotic centrosomes is regulated upstream of GCP-WD, involves multiple PCM proteins and therefore potentially multiple Plk1 substrates. PMID:19543530

  19. The non-coding RNA composition of the mitotic chromosome by 5′-tag sequencing

    PubMed Central

    Meng, Yicong; Yi, Xianfu; Li, Xinhui; Hu, Chuansheng; Wang, Ju; Bai, Ling; Czajkowsky, Daniel M.; Shao, Zhifeng

    2016-01-01

    Mitotic chromosomes are one of the most commonly recognized sub-cellular structures in eukaryotic cells. Yet basic information necessary to understand their structure and assembly, such as their composition, is still lacking. Recent proteomic studies have begun to fill this void, identifying hundreds of RNA-binding proteins bound to mitotic chromosomes. However, by contrast, there are only two RNA species (U3 snRNA and rRNA) that are known to be associated with the mitotic chromosome, suggesting that there are many mitotic chromosome-associated RNAs (mCARs) not yet identified. Here, using a targeted protocol based on 5′-tag sequencing to profile the mammalian mCAR population, we report the identification of 1279 mCARs, the majority of which are ncRNAs, including lncRNAs that exhibit greater conservation across 60 vertebrate species than the entire population of lncRNAs. There is also a significant enrichment of snoRNAs and specific SINE RNAs. Finally, ∼40% of the mCARs are presently unannotated, many of which are as abundant as the annotated mCARs, suggesting that there are also many novel ncRNAs in the mCARs. Overall, the mCARs identified here, together with the previous proteomic and genomic data, constitute the first comprehensive catalogue of the molecular composition of the eukaryotic mitotic chromosomes. PMID:27016738

  20. Co-inhibition of polo-like kinase 1 and Aurora kinases promotes mitotic catastrophe

    PubMed Central

    Li, Jingjing; Hong, Myung Jin; Chow, Jeremy P.H.; Man, Wing Yu; Mak, Joyce P.Y.; Ma, Hoi Tang; Poon, Randy Y.C.

    2015-01-01

    Mitosis is choreographed by a number of protein kinases including polo-like kinases and Aurora kinases. As these kinases are frequently dysregulated in cancers, small-molecule inhibitors have been developed for targeted anticancer therapies. Given that PLK1 and Aurora kinases possess both unique functions as well as co-regulate multiple mitotic events, whether pharmacological inhibition of these kinases together can enhance mitotic catastrophe remains an outstanding issue to be determined. Using concentrations of inhibitors that did not induce severe mitotic defects on their own, we found that both the metaphase arrest and mitotic slippage induced by inhibitors targeting Aurora A and Aurora B (MK-5108 and Barasertib respectively) were enhanced by a PLK1 inhibitor (BI 2536). We found that PLK1 is overexpressed in cells from nasopharyngeal carcinoma, a highly invasive cancer with poor prognosis, in comparison to normal nasopharyngeal epithelial cells. Nasopharyngeal carcinoma cells were more sensitive to BI 2536 as a single agent and co-inhibition with Aurora kinases than normal cells. These observations underscore the mechanism and potential benefits of targeting PLK1 and Aurora kinases to induce mitotic catastrophe in cancer cells. PMID:25871386

  1. The effect of magnesium on mitotic spindle formation in Schizosaccharomyces pombe

    PubMed Central

    Uz, Gulsen; Sarikaya, Aysegul Topal

    2016-01-01

    Abstract Magnesium (Mg2+), an essential ion for cells and biological systems, is involved in a variety of cellular processes, including the formation and breakdown of microtubules. The results of a previous investigation suggested that as cells grow the intracellular Mg2+ concentration falls, thereby stimulating formation of the mitotic spindle. In the present work, we used a Mg2+-deficient Schizosaccharomyces pombe strain GA2, in which two essential membrane Mg2+ transporter genes (homologs of ALR1 and ALR2 in Saccharomyces cerevisae) were deleted, and its parental strain Sp292, to examine the extent to which low Mg2+ concentrations can affect mitotic spindle formation. The two S. pombe strains were transformed with a plasmid carrying a GFP-α2-tubulin construct to fluorescently label microtubules. Using the free Mg2+-specific fluorescent probe mag-fura-2, we confirmed that intracellular free Mg2+ levels were lower in GA2 than in the parental strain. Defects in interphase microtubule organization, a lower percentage of mitotic spindle formation and a reduced mitotic index were also observed in the GA2 strain. Although there was interphase microtubule polymerization, the lower level of mitotic spindle formation in the Mg2+-deficient strain suggested a greater requirement for Mg2+ in this phenomenon than previously thought. PMID:27560651

  2. Phosphorylation–dephosphorylation cycle of HP1α governs accurate mitotic progression

    PubMed Central

    Chakraborty, Arindam; Prasanth, Supriya G

    2014-01-01

    Heterochromatin protein 1α (HP1α), a bona fide factor of silent chromatin, is required for establishing as well as maintaining the higher-order chromatin structure in eukaryotes. HP1α is decorated with several post-translational modifications, and many of these are critical for its cellular functions. HP1α is heavily phosphorylated; however, its physiological relevance had remained to be completely understood. We have recently demonstrated that human HP1α is a mitotic target for NDR kinase, and the phosphorylation at the hinge region of HP1α at the G2/M phase of the cell cycle is crucial for mitotic progression and Sgo1 loading at mitotic centromeres (Chakraborty et al., 2014). We now demonstrate that the dephosphorylation of HP1α within its hinge domain occurs during mitosis, specifically soon after prometaphase. In the absence of the hinge-specific HP1α phosphorylation, either as a consequence of depleting NDR1 or in cells expressing a non-phosphorylatable HP1α mutant, the cells arrest in prometaphase with several mitotic defects. In this study we show that NDR1-depleted cells expressing hinge-specific phosphomimetic HP1α mutant rescues the prometaphase arrest but displays defects in mitotic exit, suggesting that the dephosphorylation of HP1α is required for the completion of cytokinesis. Taken together, our results reveal that the phosphorylation–dephosphorylation cycle of HP1α orchestrates accurate progression of cells through mitosis. PMID:24786771

  3. UV-C irradiation delays mitotic progression by recruiting Mps1 to kinetochores.

    PubMed

    Zhang, Xiaojuan; Ling, Youguo; Wang, Wenjun; Zhang, Yanhong; Ma, Qingjun; Tan, Pingping; Song, Ting; Wei, Congwen; Li, Ping; Liu, Xuedong; Ma, Runlin Z; Zhong, Hui; Cao, Cheng; Xu, Quanbin

    2013-04-15

    The effect of UV irradiation on replicating cells during interphase has been studied extensively. However, how the mitotic cell responds to UV irradiation is less well defined. Herein, we found that UV-C irradiation (254 nm) increases recruitment of the spindle checkpoint proteins Mps1 and Mad2 to the kinetochore during metaphase, suggesting that the spindle assembly checkpoint (SAC) is reactivated. In accordance with this, cells exposed to UV-C showed delayed mitotic progression, characterized by a prolonged chromosomal alignment during metaphase. UV-C irradiation also induced the DNA damage response and caused a significant accumulation of γ-H2AX on mitotic chromosomes. Unexpectedly, the mitotic delay upon UV-C irradiation is not due to the DNA damage response but to the relocation of Mps1 to the kinetochore. Further, we found that UV-C irradiation activates Aurora B kinase. Importantly, the kinase activity of Aurora B is indispensable for full recruitment of Mps1 to the kinetochore during both prometaphase and metaphase. Taking these findings together, we propose that UV irradiation delays mitotic progression by evoking the Aurora B-Mps1 signaling cascade, which exerts its role through promoting the association of Mps1 with the kinetochore in metaphase.

  4. The KASH protein Kms2 coordinates mitotic remodeling of the spindle pole body.

    PubMed

    Wälde, Sarah; King, Megan C

    2014-08-15

    Defects in the biogenesis of the spindle pole body (SPB), the yeast centrosome equivalent, can lead to monopolar spindles and mitotic catastrophe. The KASH domain protein Kms2 and the SUN domain protein Sad1 colocalize within the nuclear envelope at the site of SPB attachment during interphase and at the spindle poles during mitosis in Schizosaccharomyces pombe. We show that Kms2 interacts with the essential SPB components Cut12 and Pcp1 and the Polo kinase Plo1. Depletion of Kms2 delays mitotic entry and leads to defects in the insertion of the SPB into the nuclear envelope, disrupting stable bipolar spindle formation. These effects are mediated in part by a delay in the recruitment of Plo1 to the SPB at mitotic entry. Plo1 activity supports mitotic SPB remodeling by driving a burst of incorporation of Cut12 and Pcp1. Thus, a fission yeast SUN-KASH complex plays an important role in supporting the remodeling of the SPB at mitotic entry.

  5. p53 deficiency enhances mitotic arrest and slippage induced by pharmacological inhibition of Aurora kinases.

    PubMed

    Marxer, M; Ma, H T; Man, W Y; Poon, R Y C

    2014-07-01

    A number of small-molecule inhibitors of Aurora kinases have been developed and are undergoing clinical trials for anti-cancer therapies. Different Aurora kinases, however, behave as very different targets: while inhibition of Aurora A (AURKA) induces a delay in mitotic exit, inhibition of Aurora B (AURKB) triggers mitotic slippage. Furthermore, while it is evident that p53 is regulated by Aurora kinase-dependent phosphorylation, how p53 may in turn regulate Aurora kinases remains mysterious. To address these issues, isogenic p53-containing and -negative cells were exposed to classic inhibitors that target both AURKA and AURKB (Alisertib and ZM447439), as well as to new generation of inhibitors that target AURKA (MK-5108), AURKB (Barasertib) individually. The fate of individual cells was then tracked with time-lapse microscopy. Remarkably, loss of p53, either by gene disruption or small interfering RNA-mediated depletion, sensitized cells to inhibition of both AURKA and AURKB, promoting mitotic arrest and slippage respectively. As the p53-dependent post-mitotic checkpoint is also important for preventing genome reduplication after mitotic slippage, these studies indicate that the loss of p53 in cancer cells represents a major opportunity for anti-cancer drugs targeting the Aurora kinases.

  6. Ki-67 acts as a biological surfactant to disperse mitotic chromosomes.

    PubMed

    Cuylen, Sara; Blaukopf, Claudia; Politi, Antonio Z; Müller-Reichert, Thomas; Neumann, Beate; Poser, Ina; Ellenberg, Jan; Hyman, Anthony A; Gerlich, Daniel W

    2016-07-14

    Eukaryotic genomes are partitioned into chromosomes that form compact and spatially well-separated mechanical bodies during mitosis. This enables chromosomes to move independently of each other for segregation of precisely one copy of the genome to each of the nascent daughter cells. Despite insights into the spatial organization of mitotic chromosomes and the discovery of proteins at the chromosome surface, the molecular and biophysical bases of mitotic chromosome structural individuality have remained unclear. Here we report that the proliferation marker protein Ki-67 (encoded by the MKI67 gene), a component of the mitotic chromosome periphery, prevents chromosomes from collapsing into a single chromatin mass after nuclear envelope disassembly, thus enabling independent chromosome motility and efficient interactions with the mitotic spindle. The chromosome separation function of human Ki-67 is not confined within a specific protein domain, but correlates with size and net charge of truncation mutants that apparently lack secondary structure. This suggests that Ki-67 forms a steric and electrostatic charge barrier, similar to surface-active agents (surfactants) that disperse particles or phase-separated liquid droplets in solvents. Fluorescence correlation spectroscopy showed a high surface density of Ki-67 and dual-colour labelling of both protein termini revealed an extended molecular conformation, indicating brush-like arrangements that are characteristic of polymeric surfactants. Our study thus elucidates a biomechanical role of the mitotic chromosome periphery in mammalian cells and suggests that natural proteins can function as surfactants in intracellular compartmentalization. PMID:27362226

  7. Dietary flavonoid fisetin induces a forced exit from mitosis by targeting the mitotic spindle checkpoint

    PubMed Central

    Salmela, Anna-Leena; Pouwels, Jeroen; Varis, Asta; Kukkonen, Anu M.; Toivonen, Pauliina; Halonen, Pasi K.; Perälä, Merja; Kallioniemi, Olli; Gorbsky, Gary J.; Kallio, Marko J.

    2009-01-01

    Fisetin is a natural flavonol present in edible vegetables, fruits and wine at 2–160 μg/g concentrations and an ingredient in nutritional supplements with much higher concentrations. The compound has been reported to exert anticarcinogenic effects as well as antioxidant and anti-inflammatory activity via its ability to act as an inhibitor of cell proliferation and free radical scavenger, respectively. Our cell-based high-throughput screen for small molecules that override chemically induced mitotic arrest identified fisetin as an antimitotic compound. Fisetin rapidly compromised microtubule drug-induced mitotic block in a proteasome-dependent manner in several human cell lines. Moreover, in unperturbed human cancer cells fisetin caused premature initiation of chromosome segregation and exit from mitosis without normal cytokinesis. To understand the molecular mechanism behind these mitotic errors, we analyzed the consequences of fisetin treatment on the localization and phoshorylation of several mitotic proteins. Aurora B, Bub1, BubR1 and Cenp-F rapidly lost their kinetochore/centromere localization and others became dephosphorylated upon addition of fisetin to the culture medium. Finally, we identified Aurora B kinase as a novel direct target of fisetin. The activity of Aurora B was significantly reduced by fisetin in vitro and in cells, an effect that can explain the observed forced mitotic exit, failure of cytokinesis and decreased cell viability. In conclusion, our data propose that fisetin perturbs spindle checkpoint signaling, which may contribute to the antiproliferative effects of the compound. PMID:19395653

  8. The effect of magnesium on mitotic spindle formation in Schizosaccharomyces pombe.

    PubMed

    Uz, Gulsen; Sarikaya, Aysegul Topal

    2016-01-01

    Magnesium (Mg2+), an essential ion for cells and biological systems, is involved in a variety of cellular processes, including the formation and breakdown of microtubules. The results of a previous investigation suggested that as cells grow the intracellular Mg2+ concentration falls, thereby stimulating formation of the mitotic spindle. In the present work, we used a Mg2+-deficient Schizosaccharomyces pombe strain GA2, in which two essential membrane Mg2+ transporter genes (homologs of ALR1 and ALR2 in Saccharomyces cerevisae) were deleted, and its parental strain Sp292, to examine the extent to which low Mg2+ concentrations can affect mitotic spindle formation. The two S. pombe strains were transformed with a plasmid carrying a GFP-α2-tubulin construct to fluorescently label microtubules. Using the free Mg2+-specific fluorescent probe mag-fura-2, we confirmed that intracellular free Mg2+ levels were lower in GA2 than in the parental strain. Defects in interphase microtubule organization, a lower percentage of mitotic spindle formation and a reduced mitotic index were also observed in the GA2 strain. Although there was interphase microtubule polymerization, the lower level of mitotic spindle formation in the Mg2+-deficient strain suggested a greater requirement for Mg2+ in this phenomenon than previously thought. PMID:27560651

  9. Co-inhibition of polo-like kinase 1 and Aurora kinases promotes mitotic catastrophe.

    PubMed

    Li, Jingjing; Hong, Myung Jin; Chow, Jeremy P H; Man, Wing Yu; Mak, Joyce P Y; Ma, Hoi Tang; Poon, Randy Y C

    2015-04-20

    Mitosis is choreographed by a number of protein kinases including polo-like kinases and Aurora kinases. As these kinases are frequently dysregulated in cancers, small-molecule inhibitors have been developed for targeted anticancer therapies. Given that PLK1 and Aurora kinases possess both unique functions as well as co-regulate multiple mitotic events, whether pharmacological inhibition of these kinases together can enhance mitotic catastrophe remains an outstanding issue to be determined. Using concentrations of inhibitors that did not induce severe mitotic defects on their own, we found that both the metaphase arrest and mitotic slippage induced by inhibitors targeting Aurora A and Aurora B (MK-5108 and Barasertib respectively) were enhanced by a PLK1 inhibitor (BI 2536). We found that PLK1 is overexpressed in cells from nasopharyngeal carcinoma, a highly invasive cancer with poor prognosis, in comparison to normal nasopharyngeal epithelial cells. Nasopharyngeal carcinoma cells were more sensitive to BI 2536 as a single agent and co-inhibition with Aurora kinases than normal cells. These observations underscore the mechanism and potential benefits of targeting PLK1 and Aurora kinases to induce mitotic catastrophe in cancer cells. PMID:25871386

  10. Greatwall dephosphorylation and inactivation upon mitotic exit is triggered by PP1.

    PubMed

    Ma, Sheng; Vigneron, Suzanne; Robert, Perle; Strub, Jean Marc; Cianferani, Sara; Castro, Anna; Lorca, Thierry

    2016-04-01

    Entry into mitosis is induced by the activation of cyclin-B-Cdk1 and Greatwall (Gwl; also known as MASTL in mammals) kinases. Cyclin-B-Cdk1 phosphorylates mitotic substrates, whereas Gwl activation promotes the phosphorylation of the small proteins Arpp19 and ENSA. Phosphorylated Arpp19 and/or ENSA bind to and inhibit PP2A comprising the B55 subunit (PP2A-B55; B55 is also known as PPP2R2A), the phosphatase responsible for cyclin-B-Cdk1 substrate dephosphorylation, allowing the stable phosphorylation of mitotic proteins. Upon mitotic exit, cyclin-B-Cdk1 and Gwl kinases are inactivated, and mitotic substrates are dephosphorylated. Here, we have identified protein phosphatase-1 (PP1) as the phosphatase involved in the dephosphorylation of the activating site (Ser875) of Gwl. Depletion of PP1 from meioticXenopusegg extracts maintains phosphorylation of Ser875, as well as the full activity of this kinase, resulting in a block of meiotic and mitotic exit. By contrast, preventing the reactivation of PP2A-B55 through the addition of a hyperactive Gwl mutant (GwlK72M) mainly affected Gwl dephosphorylation on Thr194, resulting in partial inactivation of Gwl and in the incomplete exit from mitosis or meiosis. We also show that when PP2A-B55 is fully reactivated by depleting Arpp19, this protein phosphatase is able to dephosphorylate both activating sites, even in the absence of PP1.

  11. Using in Vivo Biotinylated Ubiquitin to Describe a Mitotic Exit Ubiquitome from Human Cells *

    PubMed Central

    Min, Mingwei; Mayor, Ugo; Dittmar, Gunnar; Lindon, Catherine

    2014-01-01

    Mitotic division requires highly regulated morphological and biochemical changes to the cell. Upon commitment to exit mitosis, cells begin to remove mitotic regulators in a temporally and spatially controlled manner to bring about the changes that reestablish interphase. Ubiquitin-dependent pathways target these regulators to generate polyubiquitin-tagged substrates for degradation by the 26S proteasome. However, the lack of cell-based assays to investigate in vivo ubiquitination limits our knowledge of the identity of substrates of ubiquitin-mediated regulation in mitosis. Here we report an in vivo ubiquitin tagging system used in human cells that allows efficient purification of ubiquitin conjugates from synchronized cell populations. Coupling purification with mass spectrometry, we have identified a series of mitotic regulators targeted for polyubiquitination in mitotic exit. We show that some are new substrates of the anaphase-promoting complex/cyclosome and validate KIFC1 and RacGAP1/Cyk4 as two such targets involved respectively in timely mitotic spindle disassembly and cell spreading. We conclude that in vivo biotin tagging of ubiquitin can provide valuable information about the role of ubiquitin-mediated regulation in processes required for rebuilding interphase cells. PMID:24857844

  12. PP1 initiates the dephosphorylation of MASTL, triggering mitotic exit and bistability in human cells

    PubMed Central

    Rogers, Samuel; Fey, Dirk; McCloy, Rachael A.; Parker, Benjamin L.; Mitchell, Nicholas J.; Payne, Richard J.; Daly, Roger J.; James, David E.; Caldon, C. Elizabeth; Watkins, D. Neil; Croucher, David R.; Burgess, Andrew

    2016-01-01

    ABSTRACT Entry into mitosis is driven by the phosphorylation of thousands of substrates, under the master control of Cdk1. During entry into mitosis, Cdk1, in collaboration with MASTL kinase, represses the activity of the major mitotic protein phosphatases, PP1 and PP2A, thereby ensuring mitotic substrates remain phosphorylated. For cells to complete and exit mitosis, these phosphorylation events must be removed, and hence, phosphatase activity must be reactivated. This reactivation of phosphatase activity presumably requires the inhibition of MASTL; however, it is not currently understood what deactivates MASTL and how this is achieved. In this study, we identified that PP1 is associated with, and capable of partially dephosphorylating and deactivating, MASTL during mitotic exit. Using mathematical modelling, we were able to confirm that deactivation of MASTL is essential for mitotic exit. Furthermore, small decreases in Cdk1 activity during metaphase are sufficient to initiate the reactivation of PP1, which in turn partially deactivates MASTL to release inhibition of PP2A and, hence, create a feedback loop. This feedback loop drives complete deactivation of MASTL, ensuring a strong switch-like activation of phosphatase activity during mitotic exit. PMID:26872783

  13. Cyclin B1 overexpression induces cell death independent of mitotic arrest.

    PubMed

    Eichhorn, Joshua M; Kothari, Anisha; Chambers, Timothy C

    2014-01-01

    Microtubule inhibitors are widely used in cancer chemotherapy. These drugs characteristically induce mitotic arrest and cell death but the mechanisms linking the two are not firmly established. One of the problems is that cancer cells vary widely in their sensitivity to these agents, and thus comparison of data from different systems is difficult. To alleviate this problem we sought to molecularly induce mitotic death and study its mechanisms, by expressing non-degradable cyclin B (R42A) in HeLa cells. However, this approach failed to induce significant mitotic arrest, Cdk1 activation, or phosphorylation of anti-apoptotic Bcl-2 proteins, all characteristics of cells treated with microtubule inhibitors. Furthermore, cyclin B1-R42A induced rapid cell death, and when expressed in synchronized cells, cell death occurred in G1 phase. Decreasing the plasmid concentration reduced transfection efficiency but restored mitotic arrest and eliminated non-specific death. These results show that inappropriate overexpression of cyclin B1 causes non-specific cell death and suggest caution in its use for the study of mitotic events.

  14. Effect of caffeine and adenosine on G2 repair: mitotic delay and chromosome damage.

    PubMed

    González-Fernández, A; Hernández, P; López-Sáez, J F

    1985-04-01

    Proliferating plant cells treated during the late S period with 5-aminouracil (AU), give the typical response that DNA-damaging agents induce, characterized by: an important mitotic delay, and a potentiation of the chromosome damage by caffeine post-treatment. The study of labelled prophases, after a tritiated thymidine pulse, allowed evaluation of the mitotic delay induced by AU as well as its reversion by caffeine, while chromosome damage was estimated by the percentage of anaphases and telophases showing chromosomal aberrations. Post-treatment with adenosine alone has shown no effect on mitotic delay or chromosomal damage. However, when cells after AU were incubated in caffeine plus adenosine, the chromosome damage potentiation was abolished without affecting the caffeine action on mitotic delay. As a consequence, we postulate that caffeine could have two effects on G2 cells with damaged DNA: the first, to cancel their mitotic delay and the second to inhibit some DNA-repair pathway(s). Only this last effect could be reversed by adenosine.

  15. Phosphorylation-dephosphorylation cycle of HP1α governs accurate mitotic progression.

    PubMed

    Chakraborty, Arindam; Prasanth, Supriya G

    2014-01-01

    Heterochromatin protein 1α (HP1α), a bona fide factor of silent chromatin, is required for establishing as well as maintaining the higher-order chromatin structure in eukaryotes. HP1α is decorated with several post-translational modifications, and many of these are critical for its cellular functions. HP1α is heavily phosphorylated; however, its physiological relevance had remained to be completely understood. We have recently demonstrated that human HP1α is a mitotic target for NDR kinase, and the phosphorylation at the hinge region of HP1α at the G 2/M phase of the cell cycle is crucial for mitotic progression and Sgo1 loading at mitotic centromeres (Chakraborty et al., 2014). We now demonstrate that the dephosphorylation of HP1α within its hinge domain occurs during mitosis, specifically soon after prometaphase. In the absence of the hinge-specific HP1α phosphorylation, either as a consequence of depleting NDR1 or in cells expressing a non-phosphorylatable HP1α mutant, the cells arrest in prometaphase with several mitotic defects. In this study we show that NDR1-depleted cells expressing hinge-specific phosphomimetic HP1α mutant rescues the prometaphase arrest but displays defects in mitotic exit, suggesting that the dephosphorylation of HP1α is required for the completion of cytokinesis. Taken together, our results reveal that the phosphorylation-dephosphorylation cycle of HP1α orchestrates accurate progression of cells through mitosis.

  16. Molecular mechanism of APC/C activation by mitotic phosphorylation.

    PubMed

    Zhang, Suyang; Chang, Leifu; Alfieri, Claudio; Zhang, Ziguo; Yang, Jing; Maslen, Sarah; Skehel, Mark; Barford, David

    2016-04-27

    results reveal the mechanism for the regulation of mitotic APC/C by phosphorylation and provide a rationale for the development of selective inhibitors of this state.

  17. A case of figurate urticaria by etanercept

    PubMed Central

    Sessa, Maurizio; Sullo, Maria Giuseppa; Mascolo, Annamaria; Cimmaruta, Daniela; Romano, Francesca; Puca, Rosa Valentina; Capuano, Annalisa; Rossi, Francesco; Schiavo, Ada Lo

    2016-01-01

    Etanercept is a competitive inhibitor of tumor necrosis factor-alpha (TNF-α) a polypeptide hormone, involved in the development of the immune system, in host defense and immune surveillance. Even if the etanercept mechanism of action is not completely understood, it is supposed that it negatively modulates biological responses mediated by molecules (cytokines, adhesion molecules, or proteinases) induced or regulated by TNF. For this reason, it is widely used in the treatment of immunologicals diseases, such as rheumatoid and psoriatic arthritis, polyarticular juvenile idiopathic active, ankylosing spondylitis, and plaque psoriasis. Etanercept has a good tolerability profile. Adverse events related to skin are rare, arising usually in about 5% of patients treated with anti-TNF α. In this scenario, we describe a case of figurate urticaria arose after the re-administration of etanercept in a patient affected by psoriasis and hepatitis B. A 65-year-old man, affected by psoriasis, was hospitalized in September 2014 to the Regional Center for the treatment of psoriasis and Biological Drugs of Second University of Naples for progressive extension of psoriatic skin lesions. The laboratory analysis detected positivity for hepatitis B virus (HBV) antigens. For this reason, it was administered to him lamivudine 100 mg/die about 30 days before to start etanercept treatment. The etanercept therapy has resulted in a progressive improving of skin manifestations, and the patient decided individually to stop the therapy. Afterwards, for worsening of the psoriatic lesions, he was again hospitalized and treated with the same therapeutic schedule (lamivudine followed by etanercept). Ten days after the start of therapy, the patient showed the onset of urticarial rash. Due to this, the treatment with lamivudine and etanercept was suspended and the patient's clinical conditions improved. It is probably that immunological disorders due to etanercept therapy and HBV infection could

  18. [Genetic nature of abnormal larval development in the progeny of l(1)ts403(sbr10) females of Drosophila melanogaster].

    PubMed

    Pugacheva, O M; Mamon, L A

    2005-01-01

    In Drosophila melanogaster the small bristles (sbr) gene is vital and evolutionary conservative and controls nuclear export of mRNA. Sbr mutant alleles had a broad pleiotropic effect. High frequency of abnormal larva dying (up to 18 %) at the first instar stage in progeny of heat shock (37 degrees C, 1 h) treated mutant females is one of the most interesting l(l)ts403(sbr10) allele effects. Abnormal larvae display characteristic phenotype that involves the Malpighian tubules defect. Using interphase FISH method (fluorescence in situ hybridization), we showed that abnormal larvae had monosomy on chromosomes 2 and 3. DNA content in neuroblast interphase nuclei of abnormal larvae is 2.1 times less than in normal larvae. We suggest that abnormal larvae could be full or mosaic haploids that appeared as a result of maternal genome loss during fertilization or the mitotic division. Larvae with the same abnormalities appear in a progeny of females with different genotypes mating with males carrying compound chromosomes 2 or 3. FISH analysis showed that such larvae had monosomy only on a chromosome that is compound in paternal strain. Thus, monosomy on large autosomes may cause aspecial phenotype of abnormal larvae in D. melanogaster.

  19. Mitotic cells contract actomyosin cortex and generate pressure to round against or escape epithelial confinement.

    PubMed

    Sorce, Barbara; Escobedo, Carlos; Toyoda, Yusuke; Stewart, Martin P; Cattin, Cedric J; Newton, Richard; Banerjee, Indranil; Stettler, Alexander; Roska, Botond; Eaton, Suzanne; Hyman, Anthony A; Hierlemann, Andreas; Müller, Daniel J

    2015-11-25

    Little is known about how mitotic cells round against epithelial confinement. Here, we engineer micropillar arrays that subject cells to lateral mechanical confinement similar to that experienced in epithelia. If generating sufficient force to deform the pillars, rounding epithelial (MDCK) cells can create space to divide. However, if mitotic cells cannot create sufficient space, their rounding force, which is generated by actomyosin contraction and hydrostatic pressure, pushes the cell out of confinement. After conducting mitosis in an unperturbed manner, both daughter cells return to the confinement of the pillars. Cells that cannot round against nor escape confinement cannot orient their mitotic spindles and more likely undergo apoptosis. The results highlight how spatially constrained epithelial cells prepare for mitosis: either they are strong enough to round up or they must escape. The ability to escape from confinement and reintegrate after mitosis appears to be a basic property of epithelial cells.

  20. Mitotic cells contract actomyosin cortex and generate pressure to round against or escape epithelial confinement.

    PubMed

    Sorce, Barbara; Escobedo, Carlos; Toyoda, Yusuke; Stewart, Martin P; Cattin, Cedric J; Newton, Richard; Banerjee, Indranil; Stettler, Alexander; Roska, Botond; Eaton, Suzanne; Hyman, Anthony A; Hierlemann, Andreas; Müller, Daniel J

    2015-01-01

    Little is known about how mitotic cells round against epithelial confinement. Here, we engineer micropillar arrays that subject cells to lateral mechanical confinement similar to that experienced in epithelia. If generating sufficient force to deform the pillars, rounding epithelial (MDCK) cells can create space to divide. However, if mitotic cells cannot create sufficient space, their rounding force, which is generated by actomyosin contraction and hydrostatic pressure, pushes the cell out of confinement. After conducting mitosis in an unperturbed manner, both daughter cells return to the confinement of the pillars. Cells that cannot round against nor escape confinement cannot orient their mitotic spindles and more likely undergo apoptosis. The results highlight how spatially constrained epithelial cells prepare for mitosis: either they are strong enough to round up or they must escape. The ability to escape from confinement and reintegrate after mitosis appears to be a basic property of epithelial cells. PMID:26602832

  1. Bistability of mitotic entry and exit switches during open mitosis in mammalian cells.

    PubMed

    Hégarat, Nadia; Rata, Scott; Hochegger, Helfrid

    2016-07-01

    Mitotic entry and exit are switch-like transitions that are driven by the activation and inactivation of Cdk1 and mitotic cyclins. This simple on/off reaction turns out to be a complex interplay of various reversible reactions, feedback loops, and thresholds that involve both the direct regulators of Cdk1 and its counteracting phosphatases. In this review, we summarize the interplay of the major components of the system and discuss how they work together to generate robustness, bistability, and irreversibility. We propose that it may be beneficial to regard the entry and exit reactions as two separate reversible switches that are distinguished by differences in the state of phosphatase activity, mitotic proteolysis, and a dramatic rearrangement of cellular components after nuclear envelope breakdown, and discuss how the major Cdk1 activity thresholds could be determined for these transitions. PMID:27231150

  2. EGF-induced centrosome separation promotes mitotic progression and cell survival.

    PubMed

    Mardin, Balca R; Isokane, Mayumi; Cosenza, Marco R; Krämer, Alwin; Ellenberg, Jan; Fry, Andrew M; Schiebel, Elmar

    2013-05-13

    Timely and accurate assembly of the mitotic spindle is critical for the faithful segregation of chromosomes, and centrosome separation is a key step in this process. The timing of centrosome separation varies dramatically between cell types; however, the mechanisms responsible for these differences and its significance are unclear. Here, we show that activation of epidermal growth factor receptor (EGFR) signaling determines the timing of centrosome separation. Premature separation of centrosomes decreases the requirement for the major mitotic kinesin Eg5 for spindle assembly, accelerates mitosis, and decreases the rate of chromosome missegregation. Importantly, EGF stimulation impacts upon centrosome separation and mitotic progression to different degrees in different cell lines. Cells with high EGFR levels fail to arrest in mitosis upon Eg5 inhibition. This has important implications for cancer therapy because cells with high centrosomal response to EGF are more susceptible to combinatorial inhibition of EGFR and Eg5. PMID:23643362

  3. The post-mitotic state in neurons correlates with a stable nuclear higher-order structure.

    PubMed

    Aranda-Anzaldo, Armando

    2012-03-01

    Neurons become terminally differentiated (TD) post-mitotic cells very early during development yet they may remain alive and functional for decades. TD neurons preserve the molecular machinery necessary for DNA synthesis that may be reactivated by different stimuli but they never complete a successful mitosis. The non-reversible nature of the post-mitotic state in neurons suggests a non-genetic basis for it since no set of mutations has been able to revert it. Comparative studies of the nuclear higher-order structure in neurons and cells with proliferating potential suggest that the non-reversible nature of the post-mitotic state in neurons has a structural basis in the stability of the nuclear higher-order structure. PMID:22808316

  4. Mitotic cells contract actomyosin cortex and generate pressure to round against or escape epithelial confinement

    PubMed Central

    Sorce, Barbara; Escobedo, Carlos; Toyoda, Yusuke; Stewart, Martin P.; Cattin, Cedric J.; Newton, Richard; Banerjee, Indranil; Stettler, Alexander; Roska, Botond; Eaton, Suzanne; Hyman, Anthony A.; Hierlemann, Andreas; Müller, Daniel J.

    2015-01-01

    Little is known about how mitotic cells round against epithelial confinement. Here, we engineer micropillar arrays that subject cells to lateral mechanical confinement similar to that experienced in epithelia. If generating sufficient force to deform the pillars, rounding epithelial (MDCK) cells can create space to divide. However, if mitotic cells cannot create sufficient space, their rounding force, which is generated by actomyosin contraction and hydrostatic pressure, pushes the cell out of confinement. After conducting mitosis in an unperturbed manner, both daughter cells return to the confinement of the pillars. Cells that cannot round against nor escape confinement cannot orient their mitotic spindles and more likely undergo apoptosis. The results highlight how spatially constrained epithelial cells prepare for mitosis: either they are strong enough to round up or they must escape. The ability to escape from confinement and reintegrate after mitosis appears to be a basic property of epithelial cells. PMID:26602832

  5. p12 Tethers the Murine Leukemia Virus Pre-integration Complex to Mitotic Chromosomes

    PubMed Central

    Elis, Efrat; Ehrlich, Marcelo; Prizan-Ravid, Adi; Laham-Karam, Nihay; Bacharach, Eran

    2012-01-01

    The p12 protein of the murine leukemia virus (MLV) is a constituent of the pre-integration complex (PIC) but its function in this complex remains unknown. We developed an imaging system to monitor MLV PIC trafficking in live cells. This allowed the visualization of PIC docking to mitotic chromosomes and its release upon exit from mitosis. Docking occurred concomitantly with nuclear envelope breakdown and was impaired for PICs of viruses with lethal p12 mutations. Insertion of a heterologous chromatin binding module into p12 of one of these mutants restored PICs attachment to the chromosomes and partially rescued virus replication. Capsid dissociated from wild type PICs in mitotic cells but remained associated with PICs harboring tethering-negative p12 mutants. Altogether, these results explain, in part, MLV restriction to dividing cells and reveal a role for p12 as a factor that tethers MLV PIC to mitotic chromosomes. PMID:23300449

  6. Mitotic cells contract actomyosin cortex and generate pressure to round against or escape epithelial confinement

    NASA Astrophysics Data System (ADS)

    Sorce, Barbara; Escobedo, Carlos; Toyoda, Yusuke; Stewart, Martin P.; Cattin, Cedric J.; Newton, Richard; Banerjee, Indranil; Stettler, Alexander; Roska, Botond; Eaton, Suzanne; Hyman, Anthony A.; Hierlemann, Andreas; Müller, Daniel J.

    2015-11-01

    Little is known about how mitotic cells round against epithelial confinement. Here, we engineer micropillar arrays that subject cells to lateral mechanical confinement similar to that experienced in epithelia. If generating sufficient force to deform the pillars, rounding epithelial (MDCK) cells can create space to divide. However, if mitotic cells cannot create sufficient space, their rounding force, which is generated by actomyosin contraction and hydrostatic pressure, pushes the cell out of confinement. After conducting mitosis in an unperturbed manner, both daughter cells return to the confinement of the pillars. Cells that cannot round against nor escape confinement cannot orient their mitotic spindles and more likely undergo apoptosis. The results highlight how spatially constrained epithelial cells prepare for mitosis: either they are strong enough to round up or they must escape. The ability to escape from confinement and reintegrate after mitosis appears to be a basic property of epithelial cells.

  7. A model of DNA repeat-assembled mitotic chromosomal skeleton.

    PubMed

    Tang, Shao-Jun

    2011-01-01

    Despite intensive investigation for decades, the principle of higher-order organization of mitotic chromosomes is unclear. Here, I describe a novel model that emphasizes a critical role of interactions of homologous DNA repeats (repetitive elements; repetitive sequences) in mitotic chromosome architecture. According to the model, DNA repeats are assembled, via repeat interactions (pairing), into compact core structures that govern the arrangement of chromatins in mitotic chromosomes. Tandem repeat assemblies form a chromosomal axis to coordinate chromatins in the longitudinal dimension, while dispersed repeat assemblies form chromosomal nodes around the axis to organize chromatins in the halo. The chromosomal axis and nodes constitute a firm skeleton on which non-skeletal chromatins can be anchored, folded, and supercoiled.

  8. Mitotic Transcriptional Activation: Clearance of Actively Engaged Pol II via Transcriptional Elongation Control in Mitosis.

    PubMed

    Liang, Kaiwei; Woodfin, Ashley R; Slaughter, Brian D; Unruh, Jay R; Box, Andrew C; Rickels, Ryan A; Gao, Xin; Haug, Jeffrey S; Jaspersen, Sue L; Shilatifard, Ali

    2015-11-01

    Although it is established that some general transcription factors are inactivated at mitosis, many details of mitotic transcription inhibition (MTI) and its underlying mechanisms are largely unknown. We have identified mitotic transcriptional activation (MTA) as a key regulatory step to control transcription in mitosis for genes with transcriptionally engaged RNA polymerase II (Pol II) to activate and transcribe until the end of the gene to clear Pol II from mitotic chromatin, followed by global impairment of transcription reinitiation through MTI. Global nascent RNA sequencing and RNA fluorescence in situ hybridization demonstrate the existence of transcriptionally engaged Pol II in early mitosis. Both genetic and chemical inhibition of P-TEFb in mitosis lead to delays in the progression of cell division. Together, our study reveals a mechanism for MTA and MTI whereby transcriptionally engaged Pol II can progress into productive elongation and finish transcription to allow proper cellular division.

  9. p21 functions in a post-mitotic block checkpoint in the apoptotic response to vinblastine.

    PubMed

    Bene, Anca; Chambers, Timothy C

    2009-03-01

    We have shown previously that in KB-3 (HeLa) cells vinblastine causes downregulation of the CDK inhibitor p21 through a c-Jun regulated pathway. To test the hypothesis that p21 downregulation is necessary to alleviate a protective function, we transfected p21 in KB-3 cells and examined the apoptotic response to vinblastine. The results showed that cells overexpressing p21 were apoptosis-resistant, not through an ability of p21 to cause cell cycle arrest prior to mitotic arrest, but through altering the fate of mitotically arrested cells after drug treatment. Moreover, p21 null HCT116 cells were more prone to vinblastine-induced apoptosis relative to wild-type cells. The results provide support for a model whereby p21 downregulation promotes vinblastine-induced apoptosis by alleviating its protective function following mitotic arrest.

  10. A LCMT1-PME-1 methylation equilibrium controls mitotic spindle size.

    PubMed

    Xia, Xiaoyu; Gholkar, Ankur; Senese, Silvia; Torres, Jorge Z

    2015-01-01

    Leucine carboxyl methyltransferase-1 (LCMT1) and protein phosphatase methylesterase-1 (PME-1) are essential enzymes that regulate the methylation of the protein phosphatase 2A catalytic subunit (PP2AC). LCMT1 and PME-1 have been linked to the regulation of cell growth and proliferation, but the underlying mechanisms have remained elusive. We show here an important role for an LCMT1-PME-1 methylation equilibrium in controlling mitotic spindle size. Depletion of LCMT1 or overexpression of PME-1 led to long spindles. In contrast, depletion of PME-1, pharmacological inhibition of PME-1 or overexpression of LCMT1 led to short spindles. Furthermore, perturbation of the LCMT1-PME-1 methylation equilibrium led to mitotic arrest, spindle assembly checkpoint activation, defective cell divisions, induction of apoptosis and reduced cell viability. Thus, we propose that the LCMT1-PME-1 methylation equilibrium is critical for regulating mitotic spindle size and thereby proper cell division.

  11. A LCMT1-PME-1 methylation equilibrium controls mitotic spindle size

    PubMed Central

    Xia, Xiaoyu; Gholkar, Ankur; Senese, Silvia; Torres, Jorge Z

    2015-01-01

    Leucine carboxyl methyltransferase-1 (LCMT1) and protein phosphatase methylesterase-1 (PME-1) are essential enzymes that regulate the methylation of the protein phosphatase 2A catalytic subunit (PP2AC). LCMT1 and PME-1 have been linked to the regulation of cell growth and proliferation, but the underlying mechanisms have remained elusive. We show here an important role for an LCMT1-PME-1 methylation equilibrium in controlling mitotic spindle size. Depletion of LCMT1 or overexpression of PME-1 led to long spindles. In contrast, depletion of PME-1, pharmacological inhibition of PME-1 or overexpression of LCMT1 led to short spindles. Furthermore, perturbation of the LCMT1-PME-1 methylation equilibrium led to mitotic arrest, spindle assembly checkpoint activation, defective cell divisions, induction of apoptosis and reduced cell viability. Thus, we propose that the LCMT1-PME-1 methylation equilibrium is critical for regulating mitotic spindle size and thereby proper cell division. PMID:25839665

  12. Cohesin subunit SMC1 associates with mitotic microtubules at the spindle pole

    PubMed Central

    Wong, Richard W.; Blobel, Günter

    2008-01-01

    Accurate mitotic chromosome segregation depends on the formation of a microtubule-based bipolar spindle apparatus. We report that the cohesin subunit structural maintenance of chromosomes subunit 1 (SMC1) is recruited to microtubule-bound RNA export factor 1 (Rae1) at the mitotic spindle pole. We locate the Rae1-binding site to a 21-residue-long region, SMC1947-967 and provide several lines of evidence that phosphorylation of Ser957 and Ser966 of SMC1 stimulates binding to Rae1. Imbalances in these assembly pathways caused formation of multipolar spindles. Our data suggest that cohesin's known bundling function for chromatids in mitotic and interphase cells extends to microtubules at the spindle pole. PMID:18832153

  13. Cell fate after mitotic arrest in different tumor cells is determined by the balance between slippage and apoptotic threshold

    SciTech Connect

    Galán-Malo, Patricia; Vela, Laura; Gonzalo, Oscar; Calvo-Sanjuán, Rubén; Gracia-Fleta, Lucía; Naval, Javier; Marzo, Isabel

    2012-02-01

    Microtubule poisons and other anti-mitotic drugs induce tumor death but the molecular events linking mitotic arrest to cell death are still not fully understood. We have analyzed cell fate after mitotic arrest produced by the microtubule-destabilizing drug vincristine in a panel of human tumor cell lines showing different response to vincristine. In Jurkat, RPMI 8226 and HeLa cells, apoptosis was triggered shortly after vincristine-induced mitotic arrest. However, A549 cells, which express a great amount of Bcl-x{sub L} and undetectable amounts of Bak, underwent mitotic slippage prior to cell death. However, when Bcl-x{sub L} gene was silenced in A549 cells, vincristine induced apoptosis during mitotic arrest. Another different behavior was found in MiaPaca2 cells, where vincristine caused death by mitotic catastrophe that switched to apoptosis when cyclin B1 degradation was prevented by proteasome inhibition. Overexpression of Bcl-x{sub L} or silencing Bax and Bak expression delayed the onset of apoptosis in Jurkat and RPMI 8226 cells, enabling mitotic slippage and endoreduplication. In HeLa cells, overexpression of Bcl-x{sub L} switched cell death from apoptosis to mitotic catastrophe. Mcl-1 offered limited protection to vincristine-induced cell death and Mcl-1 degradation was not essential for vincristine-induced death. All these results, taken together, indicate that the Bcl-x{sub L}/Bak ratio and the ability to degrade cyclin B1 determine cell fate after mitotic arrest in the different tumor cell types. Highlights: ► Vincristine induces cell death by apoptosis or mitotic catastrophe. ► Apoptosis-proficient cells die by apoptosis during mitosis upon vincristine treatment. ► p53wt apoptosis-deficient cells undergo apoptosis from a G1-like tetraploid state. ► p53mt apoptosis-deficient cells can survive and divide giving rise to 8N cells.

  14. Figuring the Acceleration of the Simple Pendulum

    NASA Astrophysics Data System (ADS)

    Lieberherr, Martin

    2011-12-01

    The centripetal acceleration has been known since Huygens' (1659) and Newton's (1684) time.1,2 The physics to calculate the acceleration of a simple pendulum has been around for more than 300 years, and a fairly complete treatise has been given by C. Schwarz in this journal.3 But sentences like "the acceleration is always directed towards the equilibrium position" beside the picture of a swing on a circular arc can still be found in textbooks, as e.g. in Ref. 4. Vectors have been invented by Grassmann (1844)5 and are conveniently used to describe the acceleration in curved orbits, but acceleration is more often treated as a scalar with or without sign, as the words acceleration/deceleration suggest. The component tangential to the orbit is enough to deduce the period of the simple pendulum, but it is not enough to discuss the forces on the pendulum, as has been pointed out by Santos-Benito and A. Gras-Marti.6 A suitable way to address this problem is a nice figure with a catch for classroom discussions or homework. When I plotted the acceleration vectors of the simple pendulum in their proper positions, pictures as in Fig. 1 appeared on the screen. The endpoints of the acceleration vectors, if properly scaled, seemed to lie on a curve with a familiar shape: a cardioid. Is this true or just an illusion?

  15. Resolving the formation of modern Chladni figures

    NASA Astrophysics Data System (ADS)

    Tuan, P. H.; Tung, J. C.; Liang, H. C.; Chiang, P. Y.; Huang, K. F.; Chen, Y. F.

    2015-09-01

    The resonant spectrum of a thin plate driven with a mechanical oscillator is precisely measured to distinguish modern Chladni figures (CFs) observed at the resonant frequencies from classical CFs observed at the non-resonant frequencies. Experimental results reveal that modern CFs generally display an important characteristic of avoided crossings of nodal lines, whereas the nodal lines of classical CFs form a regular grid. The formation of modern CFs and the resonant frequency spectrum are resolved with a theoretical model that characterizes the interaction between the plate and the driving source into the inhomogeneous Kirchhoff-Love equation. The derived formula for determining resonant frequencies is shown to be exactly identical to the meromorphic function given in singular billiards that deals with the coupling strength on the transition between integrable and chaotic features. The good agreement between experimental results and theoretical predictions verifies the significant role of the strong-coupling effect in the formation of modern CFs. More importantly, it is confirmed that the apparatus for generating modern CFs can be developed to serve as an expedient system for exploring the nodal domains of chaotic wave functions as well as the physics of the strong coupling with a point scatterer.

  16. Figure skater level moderates balance training.

    PubMed

    Saunders, N W; Hanson, N J; Koutakis, P; Chaudhari, A M; Devor, S T

    2013-04-01

    It was suggested that baseline levels of postural control in figure skaters might influence the effectiveness of neuromuscular training. The aims of the present study were to investigate the baseline association of skater skill level with standard center of pressure metrics and time to stabilization, and to determine if skill level influenced the effectiveness of a 6-week neuromuscular training program. There was no main effect of skill level for any baseline center of pressure metric for either test. There was no main effect of skill level on the percent change in any metric for the single leg stance following training. However, skill level did influence landing test outcome measures. The difference in percent change of root mean squared was evident for the mediolateral (low: 24.5±16.50% vs. high: 2.42±14.99%) and anterior-posterior (low: 6.66±9.21% vs. high: - 4.03±5.91%) axes. Percent change in anterior-posterior time to stabilization also differed by skill level (low: - 0.73%±4.74 vs. high: - 5.61%±2.76). Note that this study was underpowered with 26 subjects and 14 subjects contributing to baseline and post-training assessments, respectively. Though no baseline differences in postural control were observed, compared with low skill levels, high skill levels benefitted more from training. PMID:23184479

  17. An economics figure of merit in ALPS

    SciTech Connect

    Shatilla, Y.A.

    2000-07-01

    One of the most pressing issues facing the deregulated nuclear electric power industry is its economic competitiveness when compared to other sources of electrical power. Traditionally, finding the optimum loading pattern (LP) that meets all the safety and operational objective functions and at the same time produces the most attractive economical solutions is an iterative process. This is because (a) LP search tools usually lack the capability to generate equilibrium solutions and (b) economics objective functions are hard to include in the search process. In this paper, the Westinghouse Advanced Loading Pattern Search code (ALPS) has been demonstrated to successfully find LPs that meet user-defined operational and safety as well as economics objectives. This has been made possible by the development of TULIP language that allows the integration of external procedures into the search process of the main program, ALPS. In the example given, an economic figure of merit (EFM) has been defined and included via TULIP script into the fuel management optimization problem of a three-loop Westinghouse core operating an 18-month cycle. The LPs found by ALPS exhibit a clear trend of meeting and, in some cases, exceeding the EFM objective function defined for the ALPS search process a priori.

  18. Global Phosphoproteomic Mapping of Early Mitotic Exit in Human Cells Identifies Novel Substrate Dephosphorylation Motifs.

    PubMed

    McCloy, Rachael A; Parker, Benjamin L; Rogers, Samuel; Chaudhuri, Rima; Gayevskiy, Velimir; Hoffman, Nolan J; Ali, Naveid; Watkins, D Neil; Daly, Roger J; James, David E; Lorca, Thierry; Castro, Anna; Burgess, Andrew

    2015-08-01

    Entry into mitosis is driven by the coordinated phosphorylation of thousands of proteins. For the cell to complete mitosis and divide into two identical daughter cells it must regulate dephosphorylation of these proteins in a highly ordered, temporal manner. There is currently a lack of a complete understanding of the phosphorylation changes that occur during the initial stages of mitotic exit in human cells. Therefore, we performed a large unbiased, global analysis to map the very first dephosphorylation events that occur as cells exit mitosis. We identified and quantified the modification of >16,000 phosphosites on >3300 unique proteins during early mitotic exit, providing up to eightfold greater resolution than previous studies. The data have been deposited to the ProteomeXchange with identifier PXD001559. Only a small fraction (∼ 10%) of phosphorylation sites were dephosphorylated during early mitotic exit and these occurred on proteins involved in critical early exit events, including organization of the mitotic spindle, the spindle assembly checkpoint, and reformation of the nuclear envelope. Surprisingly this enrichment was observed across all kinase consensus motifs, indicating that it is independent of the upstream phosphorylating kinase. Therefore, dephosphorylation of these sites is likely determined by the specificity of phosphatase/s rather than the activity of kinase/s. Dephosphorylation was significantly affected by the amino acids at and surrounding the phosphorylation site, with several unique evolutionarily conserved amino acids correlating strongly with phosphorylation status. These data provide a potential mechanism for the specificity of phosphatases, and how they co-ordinate the ordered events of mitotic exit. In summary, our results provide a global overview of the phosphorylation changes that occur during the very first stages of mitotic exit, providing novel mechanistic insight into how phosphatase/s specifically regulate this critical

  19. Condensin I-mediated mitotic chromosome assembly requires association with chromokinesin KIF4A.

    PubMed

    Takahashi, Motoko; Wakai, Toshifumi; Hirota, Toru

    2016-09-01

    The chromokinesin KIF4A has been implicated in shaping mitotic chromosomes, but its functional relationship to condensin complexes remains controversial. Here, we found that, in mitosis, KIF4A associates with condensin I but not with condensin II. Mutational analyses indicated that the enrichment of condensin I to chromosomal axes depends on its association with KIF4A in a way that likely involves its motor activity. Remarkably, this interaction is required for condensin I to confer physiological properties to chromosomes. These observations provide an insight into how condensin I is enriched at chromosomal axes and underscore the significance of axial structure in organizing mitotic chromosomes. PMID:27633014

  20. The morphology and symptom history of the Achilles tendons of figure skaters: an observational study

    PubMed Central

    Perry, Mark; Tillett, Eleanor; Mitchell, Sophie; Maffulli, Nicola; Morrissey, Dylan

    2012-01-01

    Summary This cross-sectional study assessed the prevalence of Achilles tendinopathy symptoms and ultrasound (US) abnormalities in male and female ice skaters, and compared this to age-matched controls. The 20 skaters of mean (sd) age 17.3 (7.9) were recruited from British figure skating clubs. The 17 non-skaters of mean age 18.0 (3.7) were recruited from a secondary school and university. Each group had 12 females. All participants completed a questionnaire, and Achilles tendons were ultrasound-scanned for thickening, hypoechoic areas, paratenon blurring and neovascularization. Skaters experienced significantly more lifetime symptoms (p=0.012) than the control group but there were no differences in present symptoms. Mid-tendon longitudinal thickness and the coefficient of variation (CoV) for longitudinal tendon thickness were significantly greater in the skaters (p=0.001 and p=0.017 respectively). No other ultrasound abnormalities were detected in either group. Figure skaters may be at a greater risk of Achilles tendon problems than the general population and have adaptive changes in their tendons. PMID:23738283

  1. Kidney transplantation in abnormal bladder

    PubMed Central

    Mishra, Shashi K.; Muthu, V.; Rajapurkar, Mohan M.; Desai, Mahesh R.

    2007-01-01

    Structural urologic abnormalities resulting in dysfunctional lower urinary tract leading to end stage renal disease may constitute 15% patients in the adult population and up to 20-30% in the pediatric population. A patient with an abnormal bladder, who is approaching end stage renal disease, needs careful evaluation of the lower urinary tract to plan the most satisfactory technical approach to the transplant procedure. Past experience of different authors can give an insight into the management and outcome of these patients. This review revisits the current literature available on transplantation in abnormal bladder and summarizes the clinical approach towards handling this group of difficult transplant patients. We add on our experience as we discuss the various issues. The outcome of renal transplant in abnormal bladder is not adversely affected when done in a reconstructed bladder. Correct preoperative evaluation, certain technical modification during transplant and postoperative care is mandatory to avoid complications. Knowledge of the abnormal bladder should allow successful transplantation with good outcome. PMID:19718334

  2. Lighting, backlighting and watercolor illusions and the laws of figurality.

    PubMed

    Pinna, Baingio; Reeves, Adam

    2006-01-01

    We report some novel 'lighting' and 'backlighting' effects in plane figures similar to those which induce the 'watercolor illusion', that is, figures made with outlines composed of juxtaposed parallel lines varying in brightness and chromatic color. These new effects show 'illumination' as an emergent percept, and show how arrangements of 'dark and light' along the boundaries of various plane figures model the volume and strengthen the illusion of depth. To account for these various effects we propose several phenomenological 'laws of figurality' to add to the Gestalt laws of organization and figure-ground segregation. We offer a set of meta-laws which are speculative but which serve to integrate and organize the phenomenological laws. These laws indicate how luminance gradient profiles across boundary contours define both the 3D appearance of figures and the properties of the light reflected from their volumetric shapes.

  3. Induced rates of mitotic crossing over and possible mitotic gene conversion per wing anlage cell in Drosophila melanogaster by X rays and fission neutrons

    SciTech Connect

    Ayaki, T.; Fujikawa, K.; Ryo, H.; Itoh, T.; Kondo, S. )

    1990-09-01

    As a model for chromosome aberrations, radiation-induced mitotic recombination of mwh and flr genes in Drosophila melanogaster strain (mwh +/+ flr) was quantitatively studied. Fission neutrons were five to six times more effective than X rays per unit dose in producing either crossover-mwh/flr twins and mwh singles-or flr singles, indicating that common processes are involved in the production of crossover and flr singles. The X-ray-induced rate/wing anlage cell/Gy for flr singles was 1 X 10(-5), whereas that of crossover was 2 x 10(-4); the former and the latter rate are of the same order of magnitude as those of gene conversion and crossover in yeast, respectively. Thus, we conclude that proximal-marker flr singles induced in the transheterozygote are gene convertants. Using the model based on yeast that recombination events result from repair of double-strand breaks or gaps, we propose that mitotic recombination in the fly is a secondary result of recombinational DNA repair. Evidence for recombinational misrepair in the fly is given. The relative ratio of radiation-induced mitotic crossover to spontaneous meiotic crossover is one order of magnitude higher in the fly than in yeast and humans.

  4. Spatial reorganization of the endoplasmic reticulum during mitosis relies on mitotic kinase cyclin A in the early Drosophila embryo.

    PubMed

    Bergman, Zane J; Mclaurin, Justin D; Eritano, Anthony S; Johnson, Brittany M; Sims, Amanda Q; Riggs, Blake

    2015-01-01

    Mitotic cyclin-dependent kinase with their cyclin partners (cyclin:Cdks) are the master regulators of cell cycle progression responsible for regulating a host of activities during mitosis. Nuclear mitotic events, including chromosome condensation and segregation have been directly linked to Cdk activity. However, the regulation and timing of cytoplasmic mitotic events by cyclin:Cdks is poorly understood. In order to examine these mitotic cytoplasmic events, we looked at the dramatic changes in the endoplasmic reticulum (ER) during mitosis in the early Drosophila embryo. The dynamic changes of the ER can be arrested in an interphase state by inhibition of either DNA or protein synthesis. Here we show that this block can be alleviated by micro-injection of Cyclin A (CycA) in which defined mitotic ER clusters gathered at the spindle poles. Conversely, micro-injection of Cyclin B (CycB) did not affect spatial reorganization of the ER, suggesting CycA possesses the ability to initiate mitotic ER events in the cytoplasm. Additionally, RNAi-mediated simultaneous inhibition of all 3 mitotic cyclins (A, B and B3) blocked spatial reorganization of the ER. Our results suggest that mitotic ER reorganization events rely on CycA and that control and timing of nuclear and cytoplasmic events during mitosis may be defined by release of CycA from the nucleus as a consequence of breakdown of the nuclear envelope.

  5. Complex patterns of abnormal heartbeats

    NASA Technical Reports Server (NTRS)

    Schulte-Frohlinde, Verena; Ashkenazy, Yosef; Goldberger, Ary L.; Ivanov, Plamen Ch; Costa, Madalena; Morley-Davies, Adrian; Stanley, H. Eugene; Glass, Leon

    2002-01-01

    Individuals having frequent abnormal heartbeats interspersed with normal heartbeats may be at an increased risk of sudden cardiac death. However, mechanistic understanding of such cardiac arrhythmias is limited. We present a visual and qualitative method to display statistical properties of abnormal heartbeats. We introduce dynamical "heartprints" which reveal characteristic patterns in long clinical records encompassing approximately 10(5) heartbeats and may provide information about underlying mechanisms. We test if these dynamics can be reproduced by model simulations in which abnormal heartbeats are generated (i) randomly, (ii) at a fixed time interval following a preceding normal heartbeat, or (iii) by an independent oscillator that may or may not interact with the normal heartbeat. We compare the results of these three models and test their limitations to comprehensively simulate the statistical features of selected clinical records. This work introduces methods that can be used to test mathematical models of arrhythmogenesis and to develop a new understanding of underlying electrophysiologic mechanisms of cardiac arrhythmia.

  6. Beyond captions: linking figures with abstract sentences in biomedical articles.

    PubMed

    Bockhorst, Joseph P; Conroy, John M; Agarwal, Shashank; O'Leary, Dianne P; Yu, Hong

    2012-01-01

    Although figures in scientific articles have high information content and concisely communicate many key research findings, they are currently under utilized by literature search and retrieval systems. Many systems ignore figures, and those that do not typically only consider caption text. This study describes and evaluates a fully automated approach for associating figures in the body of a biomedical article with sentences in its abstract. We use supervised methods to learn probabilistic language models, hidden Markov models, and conditional random fields for predicting associations between abstract sentences and figures. Three kinds of evidence are used: text in abstract sentences and figures, relative positions of sentences and figures, and the patterns of sentence/figure associations across an article. Each information source is shown to have predictive value, and models that use all kinds of evidence are more accurate than models that do not. Our most accurate method has an F1-score of 69% on a cross-validation experiment, is competitive with the accuracy of human experts, has significantly better predictive accuracy than state-of-the-art methods and enables users to access figures associated with an abstract sentence with an average of 1.82 fewer mouse clicks. A user evaluation shows that human users find our system beneficial. The system is available at http://FigureItOut.askHERMES.org.

  7. [Emotion Disorders and Abnormal Perspiration].

    PubMed

    Umeda, Satoshi

    2016-08-01

    This article reviewed the relationship between emotional disorders and abnormal perspiration. First, I focused on local brain areas related to emotional processing, and summarized the functions of the emotional network involving those local areas. Functional disorders followed by the damage in the amygdala, orbitofrontal cortex, and insular cortex were reviewed, including related abnormal perspiration. I then addressed the mechanisms of how autonomic disorders influence emotional processing. Finally, possible future directions for integrated understanding of the connection between neural activities and bodily reactions were discussed. PMID:27503817

  8. [Emotion Disorders and Abnormal Perspiration].

    PubMed

    Umeda, Satoshi

    2016-08-01

    This article reviewed the relationship between emotional disorders and abnormal perspiration. First, I focused on local brain areas related to emotional processing, and summarized the functions of the emotional network involving those local areas. Functional disorders followed by the damage in the amygdala, orbitofrontal cortex, and insular cortex were reviewed, including related abnormal perspiration. I then addressed the mechanisms of how autonomic disorders influence emotional processing. Finally, possible future directions for integrated understanding of the connection between neural activities and bodily reactions were discussed.

  9. Figures and First Years: Examining first-year Calculus I student ability to incorporate figures into technical reports

    NASA Astrophysics Data System (ADS)

    Antonacci, Nathan; Rogers, Michael; Pfaff, Thomas

    This three-year study focused on first-year Calculus I students and their abilities to incorporate figures into technical reports. Students were handed guidelines as part of their Multidisciplinary Sustainability Education Module meant to aid them in crafting effective figures. Figure-specific questionnaires were added in the class to gain insight into the quantitative literacy skills students possessed both before starting their course and after its completion. Reviews of the figures in 78 technical reports written by 106 students showed repeated failure to refer to figures in discussion sections and use them in evidence-based arguments. Analysis of quantitative literacy skills revealed that the students could both read and interpret figures, suggesting that issues with literacy were not the main contributor to the sub-par graphs.

  10. Trivalent dimethylarsenic compound induces histone H3 phosphorylation and abnormal localization of Aurora B kinase in HepG2 cells

    SciTech Connect

    Suzuki, Toshihide; Miyazaki, Koichi; Kita, Kayoko; Ochi, Takafumi

    2009-12-15

    Trivalent dimethylarsinous acid [DMA(III)] has been shown to induce mitotic abnormalities, such as centrosome abnormality, multipolar spindles, multipolar division, and aneuploidy, in several cell lines. In order to elucidate the mechanisms underlying these mitotic abnormalities, we investigated DMA(III)-mediated changes in histone H3 phosphorylation and localization of Aurora B kinase, which is a key molecule in cell mitosis. DMA(III) caused the phosphorylation of histone H3 (ser10) and was distributed predominantly in mitotic cells, especially in prometaphase cells. By contrast, most of the phospho-histone H3 was found to be localized in interphase cells after treatment with inorganic arsenite [iAs(III)], suggesting the involvement of a different pathway in phosphorylation. DMA(III) activated Aurora B kinase and slightly activated ERK MAP kinase. Phosphorylation of histone H3 by DMA(III) was effectively reduced by ZM447439 (Aurora kinase inhibitor) and slightly reduced by U0126 (MEK inhibitor). By contrast, iAs(III)-dependent histone H3 phosphorylation was markedly reduced by U0126. Aurora B kinase is generally localized in the midbody during telophase and plays an important role in cytokinesis. However, in some cells treated with DMA(III), Aurora B was not localized in the midbody of telophase cells. These findings suggested that DMA(III) induced a spindle abnormality, thereby activating the spindle assembly checkpoint (SAC) through the Aurora B kinase pathway. In addition, cytokinesis was not completed because of the abnormal localization of Aurora B kinase by DMA(III), thereby resulting in the generation of multinucleated cells. These results provide insight into the mechanism of arsenic tumorigenesis.

  11. BOOK REVIEW: Relativistic Figures of Equilibrium

    NASA Astrophysics Data System (ADS)

    Mars, M.

    2009-08-01

    Compact fluid bodies in equilibrium under its own gravitational field are abundant in the Universe and a proper treatment of them can only be carried out using the full theory of General Relativity. The problem is of enormous complexity as it involves two very different regimes, namely the interior and the exterior of the fluid, coupled through the surface of the body. This problem is very challenging both from a purely theoretical point of view, as well as regarding the obtaining of realistic models and the description of their physical properties. It is therefore an excellent piece of news that the book 'Relativistic Figures of Equilibrium' by R Meinel, M Ansorg, A Kleinwächter, G Neugebauer and D Petroff has been recently published. This book approaches the topic in depth and its contents will be of interest to a wide range of scientists working on gravitation, including theoreticians in general relativity, mathematical physicists, astrophysicists and numerical relativists. This is an advanced book that intends to present some of the present-day results on this topic. The most basic results are presented rather succinctly, and without going into the details, of their derivations. Although primarily not intended to serve as a textbook, the presentation is nevertheless self-contained and can therefore be of interest both for experts on the field as well as for anybody wishing to learn more about rotating self-gravitating compact bodies in equilibrium. It should be remarked, however, that this book makes a rather strong selection of topics and concentrates fundamentally on presenting the main results obtained by the authors during their research in this field. The book starts with a chapter where the fundamental aspects of rotating fluids in equilibrium, including its thermodynamic properties, are summarized. Of particular interest are the so-called mass-shedding limit, which is the limit where the body is rotating so fast that it is on the verge of starting

  12. Electrocardiograph abnormalities in intracerebral hemorrhage.

    PubMed

    Takeuchi, Satoru; Nagatani, Kimihiro; Otani, Naoki; Wada, Kojiro; Mori, Kentaro

    2015-12-01

    This study investigated the prevalence and type of electrocardiography (ECG) abnormalities, and their possible association with the clinical/radiological findings in 118 consecutive patients with non-traumatic, non-neoplastic intracerebral hemorrhage (ICH). ECG frequently demonstrates abnormalities in patients with ischemic stroke and subarachnoid hemorrhage, but little is known of ECG changes in ICH patients. Clinical and radiological information was retrospectively reviewed. ECG recordings that were obtained within 24 hours of the initial hemorrhage were analyzed. Sixty-six patients (56%) had one or more ECG abnormalities. The most frequent was ST depression (24%), followed by left ventricular hypertrophy (20%), corrected QT interval (QTc) prolongation (19%), and T wave inversion (19%). The logistic regression analysis demonstrated the following: insular involvement was an independent predictive factor of ST depression (p<0.001; odds ratio OR 10.18; 95% confidence interval [CI] 2.84-36.57); insular involvement (p<0.001; OR 23.98; 95% CI 4.91-117.11) and presence of intraventricular hemorrhage (p<0.001; OR 8.72; 95% CI 2.69-28.29) were independent predictive factors of QTc prolongation; deep hematoma location (p<0.001; OR 19.12; 95% CI 3.82-95.81) and hematoma volume >30 ml (p=0.001; OR 6.58; 95% CI 2.11-20.46) were independent predictive factors of T wave inversion. We demonstrate associations between ECG abnormalities and detailed characteristics of ICH.

  13. Involvement of CNOT3 in mitotic progression through inhibition of MAD1 expression

    SciTech Connect

    Takahashi, Akinori; Kikuguchi, Chisato; Morita, Masahiro; Shimodaira, Tetsuhiro; Tokai-Nishizumi, Noriko; Yokoyama, Kazumasa; Ohsugi, Miho; Suzuki, Toru; Yamamoto, Tadashi

    2012-03-09

    Highlights: Black-Right-Pointing-Pointer CNOT3 depletion increases the mitotic index. Black-Right-Pointing-Pointer CNOT3 inhibits the expression of MAD1. Black-Right-Pointing-Pointer CNOT3 destabilizes the MAD1 mRNA. Black-Right-Pointing-Pointer MAD1 knockdown attenuates the CNOT3 depletion-induced mitotic arrest. -- Abstract: The stability of mRNA influences the dynamics of gene expression. The CCR4-NOT complex, the major deadenylase in mammalian cells, shortens the mRNA poly(A) tail and contributes to the destabilization of mRNAs. The CCR4-NOT complex plays pivotal roles in various physiological functions, including cell proliferation, apoptosis, and metabolism. Here, we show that CNOT3, a subunit of the CCR4-NOT complex, is involved in the regulation of the spindle assembly checkpoint, suggesting that the CCR4-NOT complex also plays a part in the regulation of mitosis. CNOT3 depletion increases the population of mitotic-arrested cells and specifically increases the expression of MAD1 mRNA and its protein product that plays a part in the spindle assembly checkpoint. We showed that CNOT3 depletion stabilizes the MAD1 mRNA, and that MAD1 knockdown attenuates the CNOT3 depletion-induced increase of the mitotic index. Basing on these observations, we propose that CNOT3 is involved in the regulation of the spindle assembly checkpoint through its ability to regulate the stability of MAD1 mRNA.

  14. Novel insights into the mechanisms of mitotic spindle assembly by NEK kinases

    PubMed Central

    Prosser, Suzanna L.; O'Regan, Laura; Fry, Andrew M.

    2016-01-01

    ABSTRACT The mitotic spindle is the apparatus upon which chromosomes are segregated during cell division. We have discovered new roles for two members of the NIMA-related kinase (NEK) family in different molecular processes of spindle assembly. Moreover, loss of these proteins leads to segregation errors that drive cancer progression. PMID:27314078

  15. The Ki-67 and RepoMan mitotic phosphatases assemble via an identical, yet novel mechanism

    PubMed Central

    Kumar, Ganesan Senthil; Gokhan, Ezgi; De Munter, Sofie; Bollen, Mathieu; Vagnarelli, Paola; Peti, Wolfgang; Page, Rebecca

    2016-01-01

    Ki-67 and RepoMan have key roles during mitotic exit. Previously, we showed that Ki-67 organizes the mitotic chromosome periphery and recruits protein phosphatase 1 (PP1) to chromatin at anaphase onset, in a similar manner as RepoMan (Booth et al., 2014). Here we show how Ki-67 and RepoMan form mitotic exit phosphatases by recruiting PP1, how they distinguish between distinct PP1 isoforms and how the assembly of these two holoenzymes are dynamically regulated by Aurora B kinase during mitosis. Unexpectedly, our data also reveal that Ki-67 and RepoMan bind PP1 using an identical, yet novel mechanism, interacting with a PP1 pocket that is engaged only by these two PP1 regulators. These findings not only show how two distinct mitotic exit phosphatases are recruited to their substrates, but also provide immediate opportunities for the design of novel cancer therapeutics that selectively target the Ki-67:PP1 and RepoMan:PP1 holoenzymes. DOI: http://dx.doi.org/10.7554/eLife.16539.001 PMID:27572260

  16. Mitotic progression becomes irreversible in prometaphase and collapses when Wee1 and Cdc25 are inhibited

    PubMed Central

    Potapova, Tamara A.; Sivakumar, Sushama; Flynn, Jennifer N.; Li, Rong; Gorbsky, Gary J.

    2011-01-01

    Mitosis requires precise coordination of multiple global reorganizations of the nucleus and cytoplasm. Cyclin-dependent kinase 1 (Cdk1) is the primary upstream kinase that directs mitotic progression by phosphorylation of a large number of substrate proteins. Cdk1 activation reaches the peak level due to positive feedback mechanisms. By inhibiting Cdk chemically, we showed that, in prometaphase, when Cdk1 substrates approach the peak of their phosphorylation, cells become capable of proper M-to-G1 transition. We interfered with the molecular components of the Cdk1-activating feedback system through use of chemical inhibitors of Wee1 and Myt1 kinases and Cdc25 phosphatases. Inhibition of Wee1 and Myt1 at the end of the S phase led to rapid Cdk1 activation and morphologically normal mitotic entry, even in the absence of G2. Dampening Cdc25 phosphatases simultaneously with Wee1 and Myt1 inhibition prevented Cdk1/cyclin B kinase activation and full substrate phosphorylation and induced a mitotic “collapse,” a terminal state characterized by the dephosphorylation of mitotic substrates without cyclin B proteolysis. This was blocked by the PP1/PP2A phosphatase inhibitor, okadaic acid. These findings suggest that the positive feedback in Cdk activation serves to overcome the activity of Cdk-opposing phosphatases and thus sustains forward progression in mitosis. PMID:21325631

  17. The Ki-67 and RepoMan mitotic phosphatases assemble via an identical, yet novel mechanism.

    PubMed

    Kumar, Ganesan Senthil; Gokhan, Ezgi; De Munter, Sofie; Bollen, Mathieu; Vagnarelli, Paola; Peti, Wolfgang; Page, Rebecca

    2016-01-01

    Ki-67 and RepoMan have key roles during mitotic exit. Previously, we showed that Ki-67 organizes the mitotic chromosome periphery and recruits protein phosphatase 1 (PP1) to chromatin at anaphase onset, in a similar manner as RepoMan (Booth et al., 2014). Here we show how Ki-67 and RepoMan form mitotic exit phosphatases by recruiting PP1, how they distinguish between distinct PP1 isoforms and how the assembly of these two holoenzymes are dynamically regulated by Aurora B kinase during mitosis. Unexpectedly, our data also reveal that Ki-67 and RepoMan bind PP1 using an identical, yet novel mechanism, interacting with a PP1 pocket that is engaged only by these two PP1 regulators. These findings not only show how two distinct mitotic exit phosphatases are recruited to their substrates, but also provide immediate opportunities for the design of novel cancer therapeutics that selectively target the Ki-67:PP1 and RepoMan:PP1 holoenzymes. PMID:27572260

  18. The selective inhibition of protein phosphatase-1 results in mitotic catastrophe and impaired tumor growth.

    PubMed

    Winkler, Claudia; De Munter, Sofie; Van Dessel, Nele; Lesage, Bart; Heroes, Ewald; Boens, Shannah; Beullens, Monique; Van Eynde, Aleyde; Bollen, Mathieu

    2015-12-15

    The serine/threonine protein phosphatase-1 (PP1) complex is a key regulator of the cell cycle. However, the redundancy of PP1 isoforms and the lack of specific inhibitors have hampered studies on the global role of PP1 in cell cycle progression in vertebrates. Here, we show that the overexpression of nuclear inhibitor of PP1 (NIPP1; also known as PPP1R8) in HeLa cells culminated in a prometaphase arrest, associated with severe spindle-formation and chromosome-congression defects. In addition, the spindle assembly checkpoint was activated and checkpoint silencing was hampered. Eventually, most cells either died by apoptosis or formed binucleated cells. The NIPP1-induced mitotic arrest could be explained by the inhibition of PP1 that was titrated away from other mitotic PP1 interactors. Consistent with this notion, the mitotic-arrest phenotype could be rescued by the overexpression of PP1 or the inhibition of the Aurora B kinase, which acts antagonistically to PP1. Finally, we demonstrate that the overexpression of NIPP1 also hampered colony formation and tumor growth in xenograft assays in a PP1-dependent manner. Our data show that the selective inhibition of PP1 can be used to induce cancer cell death through mitotic catastrophe. PMID:26542020

  19. Frequencies of mutagen-induced coincident mitotic recombination at unlinked loci in Saccharomyces cerevisiae.

    PubMed

    Freeman, Kathryn M; Hoffmann, George R

    2007-03-01

    Frequencies of coincident genetic events were measured in strain D7 of Saccharomyces cerevisiae. This diploid strain permits the detection of mitotic gene conversion involving the trp5-12 and trp5-27 alleles, mitotic crossing-over and gene conversion leading to the expression of the ade2-40 and ade2-119 alleles as red and pink colonies, and reversion of the ilv1-92 allele. The three genes are on different chromosomes, and one might expect that coincident (simultaneous) genetic alterations at two loci would occur at frequencies predicted by those of the single alterations acting as independent events. Contrary to this expectation, we observed that ade2 recombinants induced by bleomycin, beta-propiolactone, and ultraviolet radiation occur more frequently among trp5 convertants than among total colonies. This excess among trp5 recombinants indicates that double recombinants are more common than expected for independent events. No similar enrichment was found among Ilv(+) revertants. The possibility of an artifact in which haploid yeasts that mimic mitotic recombinants are generated by a low frequency of cryptic meiosis has been excluded. Several hypotheses that can explain the elevated incidence of coincident mitotic recombination have been evaluated, but the cause remains uncertain. Most evidence suggests that the excess is ascribable to a subset of the population being in a recombination-prone state. PMID:17156798

  20. Dynamic Phosphorylation of HP1α Regulates Mitotic Progression in Human Cells

    PubMed Central

    Chakraborty, Arindam; Prasanth, Kannanganattu V.; Prasanth, Supriya G.

    2014-01-01

    Heterochromatin protein 1α (HP1α), a key player in the establishment and maintenance of higher-order chromatin regulates key cellular processes, including metaphase chromatid cohesion and centromere organization. However, how HP1α controls these processes is not well understood. Here we demonstrate that post-translational modifications of HP1α dictate its mitotic functions. HP1α is constitutively phosphorylated within its N-terminus whereas phosphorylation within the hinge domain occurs preferentially at G2/M phase of the cell cycle. The hinge-phosphorylated form of HP1α specifically localizes to kinetochores during early mitosis and this phosphorylation mediated by NDR1 kinase is required for mitotic progression and for Sgo1 binding to mitotic centromeres. Cells lacking NDR kinase show loss of mitosis-specific phosphorylation of HP1α leading to prometaphase arrest. Our results reveal that NDR kinase catalyzes the hinge-specific phosphorylation of human HP1α during G2/M in vivo and this orchestrates accurate chromosome alignment and mitotic progression. PMID:24619172

  1. The flavonoid eupatorin inactivates the mitotic checkpoint leading to polyploidy and apoptosis.

    PubMed

    Salmela, Anna-Leena; Pouwels, Jeroen; Kukkonen-Macchi, Anu; Waris, Sinikka; Toivonen, Pauliina; Jaakkola, Kimmo; Mäki-Jouppila, Jenni; Kallio, Lila; Kallio, Marko J

    2012-03-10

    The spindle assembly checkpoint (SAC) is a conserved mechanism that ensures the fidelity of chromosome distribution in mitosis by preventing anaphase onset until the correct bipolar microtubule-kinetochore attachments are formed. Errors in SAC function may contribute to tumorigenesis by inducing numerical chromosome anomalies (aneuploidy). On the other hand, total disruption of SAC can lead to massive genomic imbalance followed by cell death, a phenomena that has therapeutic potency. We performed a cell-based high-throughput screen with a compound library of 2000 bioactives for novel SAC inhibitors and discovered a plant-derived phenolic compound eupatorin (3',5-dihydroxy-4',6,7-trimethoxyflavone) as an anti-mitotic flavonoid. The premature override of the microtubule drug-imposed mitotic arrest by eupatorin is dependent on microtubule-kinetochore attachments but not interkinetochore tension. Aurora B kinase activity, which is essential for maintenance of normal SAC signaling, is diminished by eupatorin in cells and in vitro providing a mechanistic explanation for the observed forced mitotic exit. Eupatorin likely has additional targets since eupatorin treatment of pre-mitotic cells causes spindle anomalies triggering a transient M phase delay followed by impaired cytokinesis and polyploidy. Finally, eupatorin potently induces apoptosis in multiple cancer cell lines and suppresses cancer cell proliferation in organotypic 3D cell culture model.

  2. Developmental alterations in centrosome integrity contribute to the post-mitotic state of mammalian cardiomyocytes

    PubMed Central

    Zebrowski, David C; Vergarajauregui, Silvia; Wu, Chi-Chung; Piatkowski, Tanja; Becker, Robert; Leone, Marina; Hirth, Sofia; Ricciardi, Filomena; Falk, Nathalie; Giessl, Andreas; Just, Steffen; Braun, Thomas; Weidinger, Gilbert; Engel, Felix B

    2015-01-01

    Mammalian cardiomyocytes become post-mitotic shortly after birth. Understanding how this occurs is highly relevant to cardiac regenerative therapy. Yet, how cardiomyocytes achieve and maintain a post-mitotic state is unknown. Here, we show that cardiomyocyte centrosome integrity is lost shortly after birth. This is coupled with relocalization of various centrosome proteins to the nuclear envelope. Consequently, postnatal cardiomyocytes are unable to undergo ciliogenesis and the nuclear envelope adopts the function as cellular microtubule organizing center. Loss of centrosome integrity is associated with, and can promote, cardiomyocyte G0/G1 cell cycle arrest suggesting that centrosome disassembly is developmentally utilized to achieve the post-mitotic state in mammalian cardiomyocytes. Adult cardiomyocytes of zebrafish and newt, which are able to proliferate, maintain centrosome integrity. Collectively, our data provide a novel mechanism underlying the post-mitotic state of mammalian cardiomyocytes as well as a potential explanation for why zebrafish and newts, but not mammals, can regenerate their heart. DOI: http://dx.doi.org/10.7554/eLife.05563.001 PMID:26247711

  3. The flavonoid eupatorin inactivates the mitotic checkpoint leading to polyploidy and apoptosis

    SciTech Connect

    Salmela, Anna-Leena; Pouwels, Jeroen; Kukkonen-Macchi, Anu; Waris, Sinikka; Toivonen, Pauliina; Jaakkola, Kimmo; Maeki-Jouppila, Jenni; Kallio, Lila; Kallio, Marko J.

    2012-03-10

    The spindle assembly checkpoint (SAC) is a conserved mechanism that ensures the fidelity of chromosome distribution in mitosis by preventing anaphase onset until the correct bipolar microtubule-kinetochore attachments are formed. Errors in SAC function may contribute to tumorigenesis by inducing numerical chromosome anomalies (aneuploidy). On the other hand, total disruption of SAC can lead to massive genomic imbalance followed by cell death, a phenomena that has therapeutic potency. We performed a cell-based high-throughput screen with a compound library of 2000 bioactives for novel SAC inhibitors and discovered a plant-derived phenolic compound eupatorin (3 Prime ,5-dihydroxy-4 Prime ,6,7-trimethoxyflavone) as an anti-mitotic flavonoid. The premature override of the microtubule drug-imposed mitotic arrest by eupatorin is dependent on microtubule-kinetochore attachments but not interkinetochore tension. Aurora B kinase activity, which is essential for maintenance of normal SAC signaling, is diminished by eupatorin in cells and in vitro providing a mechanistic explanation for the observed forced mitotic exit. Eupatorin likely has additional targets since eupatorin treatment of pre-mitotic cells causes spindle anomalies triggering a transient M phase delay followed by impaired cytokinesis and polyploidy. Finally, eupatorin potently induces apoptosis in multiple cancer cell lines and suppresses cancer cell proliferation in organotypic 3D cell culture model.

  4. The selective inhibition of protein phosphatase-1 results in mitotic catastrophe and impaired tumor growth.

    PubMed

    Winkler, Claudia; De Munter, Sofie; Van Dessel, Nele; Lesage, Bart; Heroes, Ewald; Boens, Shannah; Beullens, Monique; Van Eynde, Aleyde; Bollen, Mathieu

    2015-12-15

    The serine/threonine protein phosphatase-1 (PP1) complex is a key regulator of the cell cycle. However, the redundancy of PP1 isoforms and the lack of specific inhibitors have hampered studies on the global role of PP1 in cell cycle progression in vertebrates. Here, we show that the overexpression of nuclear inhibitor of PP1 (NIPP1; also known as PPP1R8) in HeLa cells culminated in a prometaphase arrest, associated with severe spindle-formation and chromosome-congression defects. In addition, the spindle assembly checkpoint was activated and checkpoint silencing was hampered. Eventually, most cells either died by apoptosis or formed binucleated cells. The NIPP1-induced mitotic arrest could be explained by the inhibition of PP1 that was titrated away from other mitotic PP1 interactors. Consistent with this notion, the mitotic-arrest phenotype could be rescued by the overexpression of PP1 or the inhibition of the Aurora B kinase, which acts antagonistically to PP1. Finally, we demonstrate that the overexpression of NIPP1 also hampered colony formation and tumor growth in xenograft assays in a PP1-dependent manner. Our data show that the selective inhibition of PP1 can be used to induce cancer cell death through mitotic catastrophe.

  5. Direct preparation protocol to obtain mitotic chromosomes from canine mammary tumors.

    PubMed

    Morais, C S D; Affonso, P R A M; Bitencourt, J A; Wenceslau, A A

    2015-12-29

    Currently, mammary neoplasms in female canines are a serious problem in veterinary clinics. In addition, the canine species is an excellent disease model for human oncology because of the biological and genetic similarities between the species. Cytogenetics has allowed further study of the characterization of neoplasms in canines. We hypothesized that the use of a direct preparation protocol for mitotic chromosome analysis would provide a simple and low cost protocol for use in all laboratories. The objective of this method is to display in a few hours of dividing cells just like the time of collection since cell division in tissue can be obtained. Ten female canines with the spontaneous occurrence of mammary neoplasia were used to test a pioneering direct preparation protocol to obtain mitotic chromosomes. The excised breast tumor tissue fragments were subjected to the protocol consisting of treatment with colchicine, treatment with hypotonic solution, and fixation. Mitotic chromosomes were absent in cell suspensions of only two samples among the 10 materials analyzed, based on the analysis of five blades for each preparation obtained. So, the cell suspension obtained allowed for the observation of eight tissue samples viable for cytogenetic analysis, five of which had excellent numbers of mitotic chromosomes. However, the technique was unsuccessful in producing high-quality cell suspensions because of inadequate condensation and scattering of chromosomes. While adjustments to methodological procedures are needed, this protocol represents a low cost and simplified method to study the cytogenetics of canine tumors.

  6. Monoclonal antibody CC-3 recognizes phosphoproteins in interphase and mitotic cells.

    PubMed

    Thibodeau, A; Vincent, M

    1991-07-01

    Among a library of monoclonal antibodies (mAbs) recognizing developmental markers in the chick embryo, mAb CC-3 was selected because of its differential immunostaining of mitotic cells. The intracellular distribution of the CC-3 antigen (CC-3a) throughout the cell cycle was visualized by immunolocalization. In interphase cells CC-3a resided in the nucleus and was arranged in distinct extranucleolar clusters. At prophase, the nuclear reactivity of CC-3a considerably increased and subsequently extended to the cytoplasm at metaphase. From metaphase through anaphase, most of the reactivity was associated with the mitotic apparatus. During cytokinesis CC-3a was detected in the mid-body and also in discrete speckles dispersed throughout the cytoplasm. The initial interphase pattern was then restored in the two daughter nuclei. Immunoblot analysis demonstrated that a 255-kDa phosphoprotein was present only in the interphase nucleus and that a complete new set of phosphoproteins accounted for the mitotic cell reactivity. The binding of CC-3 was dependent on the phosphorylation of its antigens. CC-3a is an evolutionary conserved molecule; it is present in such phylogenetically distant species as Drosophila and humans. Furthermore, the unique behavior of CC-3 on sections of normal, embryonic, and regenerative tissue and in cell culture immunostaining make it a reliable tool to identify mitotic foci.

  7. The deubiquitinating enzyme complex BRISC is required for proper mitotic spindle assembly in mammalian cells

    PubMed Central

    Yan, Kaowen; Li, Li; Wang, Xiaojian; Hong, Ruisha; Zhang, Ying; Yang, Hua; Lin, Ming; Zhang, Sha; He, Qihua; Zheng, Duo; Tang, Jun; Yin, Yuxin

    2015-01-01

    Deubiquitinating enzymes (DUBs) negatively regulate protein ubiquitination and play an important role in diverse physiological processes, including mitotic division. The BRCC36 isopeptidase complex (BRISC) is a DUB that is specific for lysine 63–linked ubiquitin hydrolysis; however, its biological function remains largely undefined. Here, we identify a critical role for BRISC in the control of mitotic spindle assembly in cultured mammalian cells. BRISC is a microtubule (MT)-associated protein complex that predominantly localizes to the minus ends of K-fibers and spindle poles and directly binds to MTs; importantly, BRISC promotes the assembly of functional bipolar spindle by deubiquitinating the essential spindle assembly factor nuclear mitotic apparatus (NuMA). The deubiquitination of NuMA regulates its interaction with dynein and importin-β, which are required for its function in spindle assembly. Collectively, these results uncover BRISC as an important regulator of the mitotic spindle assembly and cell division, and have important implications for the development of anticancer drugs targeting BRISC. PMID:26195665

  8. Bub1 kinase activity drives error correction and mitotic checkpoint control but not tumor suppression

    PubMed Central

    Ricke, Robin M.; Jeganathan, Karthik B.; Malureanu, Liviu; Harrison, Andrew M.

    2012-01-01

    The mitotic checkpoint protein Bub1 is essential for embryogenesis and survival of proliferating cells, and bidirectional deviations from its normal level of expression cause chromosome missegregation, aneuploidy, and cancer predisposition in mice. To provide insight into the physiological significance of this critical mitotic regulator at a modular level, we generated Bub1 mutant mice that lack kinase activity using a knockin gene-targeting approach that preserves normal protein abundance. In this paper, we uncover that Bub1 kinase activity integrates attachment error correction and mitotic checkpoint signaling by controlling the localization and activity of Aurora B kinase through phosphorylation of histone H2A at threonine 121. Strikingly, despite substantial chromosome segregation errors and aneuploidization, mice deficient for Bub1 kinase activity do not exhibit increased susceptibility to spontaneous or carcinogen-induced tumorigenesis. These findings provide a unique example of a modular mitotic activity orchestrating two distinct networks that safeguard against whole chromosome instability and reveal the differential importance of distinct aneuploidy-causing Bub1 defects in tumor suppression. PMID:23209306

  9. A mitotic SKAP isoform regulates spindle positioning at astral microtubule plus ends.

    PubMed

    Kern, David M; Nicholls, Peter K; Page, David C; Cheeseman, Iain M

    2016-05-01

    The Astrin/SKAP complex plays important roles in mitotic chromosome alignment and centrosome integrity, but previous work found conflicting results for SKAP function. Here, we demonstrate that SKAP is expressed as two distinct isoforms in mammals: a longer, testis-specific isoform that was used for the previous studies in mitotic cells and a novel, shorter mitotic isoform. Unlike the long isoform, short SKAP rescues SKAP depletion in mitosis and displays robust microtubule plus-end tracking, including localization to astral microtubules. Eliminating SKAP microtubule binding results in severe chromosome segregation defects. In contrast, SKAP mutants specifically defective for plus-end tracking facilitate proper chromosome segregation but display spindle positioning defects. Cells lacking SKAP plus-end tracking have reduced Clasp1 localization at microtubule plus ends and display increased lateral microtubule contacts with the cell cortex, which we propose results in unbalanced dynein-dependent cortical pulling forces. Our work reveals an unappreciated role for the Astrin/SKAP complex as an astral microtubule mediator of mitotic spindle positioning. PMID:27138257

  10. Cell cycle-dependent SUMO-1 conjugation to nuclear mitotic apparatus protein (NuMA)

    SciTech Connect

    Seo, Jae Sung; Kim, Ha Na; Kim, Sun-Jick; Bang, Jiyoung; Kim, Eun-A; Sung, Ki Sa; Yoon, Hyun-Joo; Yoo, Hae Yong; Choi, Cheol Yong

    2014-01-03

    Highlights: •NuMA is modified by SUMO-1 in a cell cycle-dependent manner. •NuMA lysine 1766 is the primary target site for SUMOylation. •SUMOylation-deficient NuMA induces multiple spindle poles during mitosis. •SUMOylated NuMA induces microtubule bundling. -- Abstract: Covalent conjugation of proteins with small ubiquitin-like modifier 1 (SUMO-1) plays a critical role in a variety of cellular functions including cell cycle control, replication, and transcriptional regulation. Nuclear mitotic apparatus protein (NuMA) localizes to spindle poles during mitosis, and is an essential component in the formation and maintenance of mitotic spindle poles. Here we show that NuMA is a target for covalent conjugation to SUMO-1. We find that the lysine 1766 residue is the primary NuMA acceptor site for SUMO-1 conjugation. Interestingly, SUMO modification of endogenous NuMA occurs at the entry into mitosis and this modification is reversed after exiting from mitosis. Knockdown of Ubc9 or forced expression of SENP1 results in impairment of the localization of NuMA to mitotic spindle poles during mitosis. The SUMOylation-deficient NuMA mutant is defective in microtubule bundling, and multiple spindles are induced during mitosis. The mitosis-dependent dynamic SUMO-1 modification of NuMA might contribute to NuMA-mediated formation and maintenance of mitotic spindle poles during mitosis.

  11. Mitotic phosphorylation of VCIP135 blocks p97ATPase-mediated Golgi membrane fusion

    SciTech Connect

    Totsukawa, Go; Matsuo, Ayaka; Kubota, Ayano; Taguchi, Yuya; Kondo, Hisao

    2013-04-05

    Highlights: •VCIP135 is mitotically phosphorylated on Threonine-760 and Serine-767 by Cdc2. •Phosphorylated VCIP135 does not bind to p97ATPase. •The phosphorylation of VCIP135 inhibits p97ATPase-mediated Golgi membrane fusion. -- Abstract: In mammals, the Golgi apparatus is disassembled early mitosis and reassembled at the end of mitosis. For Golgi disassembly, membrane fusion needs to be blocked. Golgi biogenesis requires two distinct p97ATPase-mediated membrane fusion, the p97/p47 and p97/p37 pathways. We previously reported that p47 phosphorylation on Serine-140 and p37 phosphorylation on Serine-56 and Threonine-59 result in mitotic inhibition of the p97/p47 and the p97/p37 pathways, respectively [11,14]. In this study, we show another mechanism of mitotic inhibition of p97-mediated Golgi membrane fusion. We clarified that VCIP135, an essential factor in both p97 membrane fusion pathways, is phosphorylated on Threonine-760 and Serine-767 by Cdc2 at mitosis and that this phosphorylated VCIP135 does not bind to p97. An in vitro Golgi reassembly assay revealed that VCIP135(T760E, S767E), which mimics mitotic phosphorylation, caused no cisternal regrowth. Our results indicate that the phosphorylation of VCIP135 on Threonine-760 and Serine-767 inhibits p97-mediated Golgi membrane fusion at mitosis.

  12. Regulation of Mitotic Cytoskeleton Dynamics and Cytokinesis by Integrin-Linked Kinase in Retinoblastoma Cells

    PubMed Central

    Sharma, Manju; Assi, Kiran; Salh, Baljinder; Cox, Michael E.; Mills, Julia

    2014-01-01

    During cell division integrin-linked kinase (ILK) has been shown to regulate microtubule dynamics and centrosome clustering, processes involved in cell cycle progression, and malignant transformation. In this study, we examine the effects of downregulating ILK on mitotic function in human retinoblastoma cell lines. These retinal cancer cells, caused by the loss of function of two gene alleles (Rb1) that encode the retinoblastoma tumour suppressor, have elevated expression of ILK. Here we show that inhibition of ILK activity results in a concentration-dependent increase in nuclear area and multinucleated cells. Moreover, inhibition of ILK activity and expression increased the accumulation of multinucleated cells over time. In these cells, aberrant cytokinesis and karyokinesis correlate with altered mitotic spindle organization, decreased levels of cortical F-actin and centrosome de-clustering. Centrosome de-clustering, induced by ILK siRNA, was rescued in FLAG-ILK expressing Y79 cells as compared to those expressing FLAG-tag alone. Inhibition of ILK increased the proportion of cells exhibiting mitotic spindles and caused a significant G2/M arrest as early as 24 hours after exposure to QLT-0267. Live cell analysis indicate ILK downregulation causes an increase in multipolar anaphases and failed cytokinesis (bipolar and multipolar) of viable cells. These studies extend those indicating a critical function for ILK in mitotic cytoskeletal organization and describe a novel role for ILK in cytokinesis of Rb deficient cells. PMID:24911651

  13. Regulation of mitotic cytoskeleton dynamics and cytokinesis by integrin-linked kinase in retinoblastoma cells.

    PubMed

    Sikkema, William K A; Strikwerda, Arend; Sharma, Manju; Assi, Kiran; Salh, Baljinder; Cox, Michael E; Mills, Julia

    2014-01-01

    During cell division integrin-linked kinase (ILK) has been shown to regulate microtubule dynamics and centrosome clustering, processes involved in cell cycle progression, and malignant transformation. In this study, we examine the effects of downregulating ILK on mitotic function in human retinoblastoma cell lines. These retinal cancer cells, caused by the loss of function of two gene alleles (Rb1) that encode the retinoblastoma tumour suppressor, have elevated expression of ILK. Here we show that inhibition of ILK activity results in a concentration-dependent increase in nuclear area and multinucleated cells. Moreover, inhibition of ILK activity and expression increased the accumulation of multinucleated cells over time. In these cells, aberrant cytokinesis and karyokinesis correlate with altered mitotic spindle organization, decreased levels of cortical F-actin and centrosome de-clustering. Centrosome de-clustering, induced by ILK siRNA, was rescued in FLAG-ILK expressing Y79 cells as compared to those expressing FLAG-tag alone. Inhibition of ILK increased the proportion of cells exhibiting mitotic spindles and caused a significant G2/M arrest as early as 24 hours after exposure to QLT-0267. Live cell analysis indicate ILK downregulation causes an increase in multipolar anaphases and failed cytokinesis (bipolar and multipolar) of viable cells. These studies extend those indicating a critical function for ILK in mitotic cytoskeletal organization and describe a novel role for ILK in cytokinesis of Rb deficient cells. PMID:24911651

  14. Miniaturization of mitotic index cell-based assay using "wall-less" plate technology.

    PubMed

    Le Guezennec, Xavier; Phong, Mark; Nor, Liyana; Kim, Namyong

    2014-03-01

    The use of microscopic imaging for the accurate assessment of cells in mitosis is hampered by the round morphology of mitotic cells, which renders them poorly adherent and highly susceptible to loss during the washing stage of cell-based assays. Here, to circumvent these limitations, we make use of DropArray, a recent technology that allows high retention of weakly adherent cells and suspension cells. DropArray offers the competitive advantage of maintaining the classic high throughput format of microtiter plates while reducing classic microwell volume by up to 90% by using a drop format. Here, we present a mitotic index cell-based assay using the mitosis marker phospho histone H3 at serine 10 on a DropArray 384-well plate format. Dose-response curve analysis of the mitotic index assay with an antimitotic drug (docetaxel) on DropArray is presented that shows an effective dosage compared to previous established results similar to those obtained with conventional microtiter plates. The mitotic index assay with DropArray showed a Z-factor >0.6. Our results validate DropArray as a suitable platform for high throughput screening for compounds affecting mitosis or the cell cycle. PMID:24611478

  15. Changes after irradiation in the number of mitotic cells and apoptotic fragments in growing mouse hair follicles and in the width of their hairs

    SciTech Connect

    Geng, L.; Potten, C.S. )

    1990-07-01

    The hair follicle or its differentiated product, the hair, which represents the linear historical record of the follicular proliferative activity, could provide a biological dosimeter of value for dose distribution determinations after accidental exposure. Here we present some further studies on irradiated mouse hair follicles and hair, and discuss the difficulties in obtaining similar data for humans. The incidence of cell death in the follicles has been shown elsewhere to be maximum 12 h after irradiation, and it increases with dose. Here we confirm that doses of 0.2-0.4 Gy can be readily detected. We show here that there is only a little more cell death in the larger follicles even though they contain many more cells and mitotic figures. About one-third of all the dead cell fragments in a follicle can be seen in a good longitudinal follicle section. Mitotic activity declines progressively with dose in the large follicles, which start with more mitotic cells, showing the dose-dependent changes most readily. The dead cells are morphologically identical to apoptotic cells at the level of the light microscope, and they fragment into several bodies, the number of which increases with dose. The total number of apoptotic bodies or fragments in whole large follicles increases almost 100-fold over a range of 1.3 Gy (from 0.2 to 1.5 Gy) and about tenfold over the range 0.2-0.5 Gy. The estimated number of dead (apoptotic) cells increases about sevenfold over the same 1.3-Gy range. The width of the middle portion of the broadest, awl, hairs measured 12 days after irradiation decreases with increasing dose. About 80% of the hairs show an obvious reduction in width after 2 Gy and the effects of a dose of about 1 Gy can be detected. The width of the hair is reduced by 10-14% per Gy. A comparison has been made between BDF1 (black) and BALB-c (albino) mice.

  16. 16 CFR Figure 8 to Part 1610 - Brush

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Brush 8 Figure 8 to Part 1610 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FLAMMABLE FABRICS ACT REGULATIONS STANDARD FOR THE FLAMMABILITY OF CLOTHING TEXTILES Pt.1610, Fig. 8 Figure 8 to Part 1610—Brush ER25MR08.007...

  17. 16 CFR Figure 9 to Part 1610 - Brushing Device Template

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Brushing Device Template 9 Figure 9 to Part 1610 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FLAMMABLE FABRICS ACT REGULATIONS STANDARD FOR THE FLAMMABILITY OF CLOTHING TEXTILES Pt.1610, Fig. 9 Figure 9 to Part 1610—Brushing...

  18. 16 CFR Figure 9 to Part 1610 - Brushing Device Template

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 2 2011-01-01 2011-01-01 false Brushing Device Template 9 Figure 9 to Part 1610 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FLAMMABLE FABRICS ACT REGULATIONS STANDARD FOR THE FLAMMABILITY OF CLOTHING TEXTILES Pt.1610, Fig. 9 Figure 9 to Part 1610—Brushing...

  19. 16 CFR Figure 6 to Part 1610 - Igniter

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 2 2011-01-01 2011-01-01 false Igniter 6 Figure 6 to Part 1610 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FLAMMABLE FABRICS ACT REGULATIONS STANDARD FOR THE FLAMMABILITY OF CLOTHING TEXTILES Pt.1610, Fig. 6 Figure 6 to Part 1610—Igniter ER20OC08.001...

  20. 16 CFR Figure 8 to Part 1610 - Brush

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 2 2011-01-01 2011-01-01 false Brush 8 Figure 8 to Part 1610 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FLAMMABLE FABRICS ACT REGULATIONS STANDARD FOR THE FLAMMABILITY OF CLOTHING TEXTILES Pt.1610, Fig. 8 Figure 8 to Part 1610—Brush ER25MR08.007...

  1. 16 CFR Figure 7 to Part 1610 - Brushing Device

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 2 2011-01-01 2011-01-01 false Brushing Device 7 Figure 7 to Part 1610 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FLAMMABLE FABRICS ACT REGULATIONS STANDARD FOR THE FLAMMABILITY OF CLOTHING TEXTILES Pt.1610, Fig. 7 Figure 7 to Part 1610—Brushing Device ER25MR08.006...

  2. 16 CFR Figure 6 to Part 1610 - Igniter

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Igniter 6 Figure 6 to Part 1610 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FLAMMABLE FABRICS ACT REGULATIONS STANDARD FOR THE FLAMMABILITY OF CLOTHING TEXTILES Pt.1610, Fig. 6 Figure 6 to Part 1610—Igniter ER20OC08.001...

  3. 16 CFR Figure 7 to Part 1610 - Brushing Device

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Brushing Device 7 Figure 7 to Part 1610 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FLAMMABLE FABRICS ACT REGULATIONS STANDARD FOR THE FLAMMABILITY OF CLOTHING TEXTILES Pt.1610, Fig. 7 Figure 7 to Part 1610—Brushing Device ER25MR08.006...

  4. 16 CFR Figure 2 to Part 1508 - Headform Probe

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 2 2014-01-01 2014-01-01 false Headform Probe 2 Figure 2 to Part 1508 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS FIREWORKS DEVICES Multiple-tube fireworks devices. Pt. 1508, Fig. 2 Figure 2 to Part 1508—Headform...

  5. 40 CFR Appendix B to Subpart D of... - Figures

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 21 2013-07-01 2013-07-01 false Figures B Appendix B to Subpart D of Part 89 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED... Provisions Pt. 89, Subpt. D, App. B Appendix B to Subpart D of Part 89—Figures EC01MR92.000 EC01MR92.001...

  6. 40 CFR Appendix B to Subpart D of... - Figures

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 21 2013-07-01 2013-07-01 false Figures B Appendix B to Subpart D of Part 91 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED.... D, App. B Appendix B to Subpart D of Part 91—Figures ER04OC96.013 ER04OC96.014...

  7. 40 CFR Figure B-1 to Subpart B of... - Example

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 6 2012-07-01 2012-07-01 false Example B Figure B-1 to Subpart B of Part 53 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED... of Automated Methods for SO2, CO, O3, and NO2 Pt. 53, Subpt. B, Fig. B-1 Figure B-1 to Subpart B...

  8. 40 CFR Appendix B to Subpart E of... - Figures

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 21 2013-07-01 2013-07-01 false Figures B Appendix B to Subpart E of Part 90 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED... Procedures Pt. 90, Subpt. E, App. B Appendix B to Subpart E of Part 90—Figures EC01MR92.087...

  9. 40 CFR Appendix B to Subpart D of... - Figures

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 21 2013-07-01 2013-07-01 false Figures B Appendix B to Subpart D of Part 90 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED... Provisions Pt. 90, Subpt. D, App. B Appendix B to Subpart D of Part 90—Figures EC01MR92.085 EC01MR92.086...

  10. 40 CFR Figure B-1 to Subpart B of... - Example

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 6 2013-07-01 2013-07-01 false Example B Figure B-1 to Subpart B of Part 53 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED... of Automated Methods for SO2, CO, O3, and NO2 Pt. 53, Subpt. B, Fig. B-1 Figure B-1 to Subpart B...

  11. 40 CFR Figure B-1 to Subpart B of... - Example

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 6 2014-07-01 2014-07-01 false Example B Figure B-1 to Subpart B of Part 53 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED... of Automated Methods for SO2, CO, O3, and NO2 Pt. 53, Subpt. B, Fig. B-1 Figure B-1 to Subpart B...

  12. 16 CFR Figure 6 to Part 1203 - Field of Vision

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Field of Vision 6 Figure 6 to Part 1203 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT SAFETY ACT REGULATIONS SAFETY STANDARD FOR BICYCLE HELMETS Pt. 1203, Fig. 6 Figure 6 to Part 1203—Field of Vision ER10MR98.006...

  13. 16 CFR Figure 6 to Part 1203 - Field of Vision

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 2 2011-01-01 2011-01-01 false Field of Vision 6 Figure 6 to Part 1203 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT SAFETY ACT REGULATIONS SAFETY STANDARD FOR BICYCLE HELMETS Pt. 1203, Fig. 6 Figure 6 to Part 1203—Field of Vision ER10MR98.006...

  14. 16 CFR Figure 6 to Part 1203 - Field of Vision

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 16 Commercial Practices 2 2012-01-01 2012-01-01 false Field of Vision 6 Figure 6 to Part 1203 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT SAFETY ACT REGULATIONS SAFETY STANDARD FOR BICYCLE HELMETS Pt. 1203, Fig. 6 Figure 6 to Part 1203—Field of Vision ER10MR98.006...

  15. 16 CFR Figure 6 to Part 1203 - Field of Vision

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 2 2014-01-01 2014-01-01 false Field of Vision 6 Figure 6 to Part 1203 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT SAFETY ACT REGULATIONS SAFETY STANDARD FOR BICYCLE HELMETS Pt. 1203, Fig. 6 Figure 6 to Part 1203—Field of Vision ER10MR98.006...

  16. 16 CFR Figure 6 to Part 1203 - Field of Vision

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 16 Commercial Practices 2 2013-01-01 2013-01-01 false Field of Vision 6 Figure 6 to Part 1203 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT SAFETY ACT REGULATIONS SAFETY STANDARD FOR BICYCLE HELMETS Pt. 1203, Fig. 6 Figure 6 to Part 1203—Field of Vision ER10MR98.006...

  17. Distinguishing between Realistic and Fantastical Figures in Iran

    ERIC Educational Resources Information Center

    Davoodi, Telli; Corriveau, Kathleen H.; Harris, Paul L.

    2016-01-01

    Children in the United States come to distinguish historical from fictional story figures between the ages of 3 and 5 years, guided by the plausibility of the story events surrounding the figure (Corriveau, Kim, Schwalen, & Harris, 2009; Woolley & Cox, 2007). However, U.S. children vary in their reactions to stories that include…

  18. 16 CFR Figure 9 to Part 1203 - Impact Test Apparatus

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 2 2011-01-01 2011-01-01 false Impact Test Apparatus 9 Figure 9 to Part 1203 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT SAFETY ACT REGULATIONS SAFETY STANDARD FOR BICYCLE HELMETS Pt. 1203, Fig. 9 Figure 9 to Part 1203—Impact Test Apparatus...

  19. 16 CFR Figure 9 to Part 1203 - Impact Test Apparatus

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Impact Test Apparatus 9 Figure 9 to Part 1203 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT SAFETY ACT REGULATIONS SAFETY STANDARD FOR BICYCLE HELMETS Pt. 1203, Fig. 9 Figure 9 to Part 1203—Impact Test Apparatus...

  20. 50 CFR Figure 10 to Part 223 - Flounder TED

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 10 2012-10-01 2012-10-01 false Flounder TED 10 Figure 10 to Part 223 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE MARINE MAMMALS THREATENED MARINE AND ANADROMOUS SPECIES Pt. 223, Fig. 10 Figure 10...

  1. 50 CFR Figures 1-2 to Part 223 - [Reserved

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 10 2012-10-01 2012-10-01 false 1 Figures 1-2 to Part 223 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE MARINE MAMMALS THREATENED MARINE AND ANADROMOUS SPECIES Figures 1-2 to Part 223...

  2. 50 CFR Figure 3 to Part 223 - Matagorda TED

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 9 2011-10-01 2011-10-01 false Matagorda TED 3 Figure 3 to Part 223 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE MARINE MAMMALS THREATENED MARINE AND ANADROMOUS SPECIES Pt. 223, Fig. 3 Figure 3...

  3. 50 CFR Figure 11 to Part 223 - [Reserved

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 9 2011-10-01 2011-10-01 false 11 Figure 11 to Part 223 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE MARINE MAMMALS THREATENED MARINE AND ANADROMOUS SPECIES Figure 11 to Part 223...

  4. 50 CFR Figure 4 to Part 223 - Georgia TED

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 9 2011-10-01 2011-10-01 false Georgia TED 4 Figure 4 to Part 223 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE MARINE MAMMALS THREATENED MARINE AND ANADROMOUS SPECIES Pt. 223, Fig. 4 Figure 4...

  5. 50 CFR Figures 1-2 to Part 223 - [Reserved

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 9 2011-10-01 2011-10-01 false 1 Figures 1-2 to Part 223 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE MARINE MAMMALS THREATENED MARINE AND ANADROMOUS SPECIES Figures 1-2 to Part 223...

  6. 50 CFR Figure 10 to Part 223 - Flounder TED

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 9 2011-10-01 2011-10-01 false Flounder TED 10 Figure 10 to Part 223 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE MARINE MAMMALS THREATENED MARINE AND ANADROMOUS SPECIES Pt. 223, Fig. 10 Figure 10...

  7. 50 CFR Figure 4 to Part 223 - Georgia TED

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 10 2012-10-01 2012-10-01 false Georgia TED 4 Figure 4 to Part 223 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE MARINE MAMMALS THREATENED MARINE AND ANADROMOUS SPECIES Pt. 223, Fig. 4 Figure 4...

  8. 50 CFR Figure 3 to Part 223 - Matagorda TED

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 10 2012-10-01 2012-10-01 false Matagorda TED 3 Figure 3 to Part 223 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE MARINE MAMMALS THREATENED MARINE AND ANADROMOUS SPECIES Pt. 223, Fig. 3 Figure 3...

  9. Protocol Analysis of Aptitude Differences in Figural Analogy Problem Representation.

    ERIC Educational Resources Information Center

    Schiano, Diane J.

    Individual differences in performance on figural analogy tests are usually attributed to quantitative differences in processing parameters rather than to qualitative differences in the formation and use of representations. Yet aptitude-related differences in categorizing standardized figural analogy problems between high and low scorers have been…

  10. Interpreting Children's Human Figure Drawings: Basic Guidelines for School Counselors

    ERIC Educational Resources Information Center

    Foley, Yuehong Chen; Mullis, Fran

    2008-01-01

    The literature was reviewed and summarized to provide common interpretations of human figure drawings. Basic guidelines for interpreting human figure drawings (i.e., face and head, body, arms and hands, and legs and feet) are presented. Expectations for students at different developmental levels (ages 1 1/2 through adolescence) are identified, and…

  11. 16 CFR Figures 3 and 4 to Subpart... - Test Specimens

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 16 Commercial Practices 2 2012-01-01 2012-01-01 false Test Specimens 3 Figures 3 and 4 to Subpart A of Part 1201 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT SAFETY ACT... Figures 3 and 4 to Subpart A of Part 1201—Test Specimens EC03OC91.006...

  12. Activation of Conventional Meaning during the Processing of Figurative Language.

    ERIC Educational Resources Information Center

    Turner, Nigel; Katz, Albert

    Two studies investigated the processing of familiar and unfamiliar figurative language. Subjects read paragraphs containing figurative sentences (proverbs in study 1 and metaphors in study 2) or literal controls; later subjects were given a cued recall test designed to test their memory for contextually inappropriate meanings (a literal cue for a…

  13. Dynamic Reaction Figures: An Integrative Vehicle for Understanding Chemical Reactions

    ERIC Educational Resources Information Center

    Schultz, Emeric

    2008-01-01

    A highly flexible learning tool, referred to as a dynamic reaction figure, is described. Application of these figures can (i) yield the correct chemical equation by simply following a set of menu driven directions; (ii) present the underlying "mechanism" in chemical reactions; and (iii) help to solve quantitative problems in a number of different…

  14. 47 CFR Figure 1 to Subpart N of... - Measurement Site

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 1 2011-10-01 2011-10-01 false Measurement Site 1 Figure 1 to Subpart N of Part 2 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL FREQUENCY ALLOCATIONS AND RADIO... Position Indicating Radiobeacons (EPIRBs) Pt. 2, Subpt. N, Fig. 1 Figure 1 to Subpart N of Part...

  15. Determination of Visual Figure and Ground in Dynamically Deforming Shapes

    ERIC Educational Resources Information Center

    Barenholtz, Elan; Feldman, Jacob

    2006-01-01

    Figure/ground assignment--determining which part of the visual image is foreground and which background--is a critical step in early visual analysis, upon which much later processing depends. Previous research on the assignment of figure and ground to opposing sides of a contour has almost exclusively involved static geometric factors--such as…

  16. 16 CFR Figure 2 to Part 1511 - Small Parts Gage

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 2 2014-01-01 2014-01-01 false Small Parts Gage 2 Figure 2 to Part 1511 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS REQUIREMENTS FOR PACIFIERS Pt.1511, Fig. 2 Figure 2 to Part 1511—Small Parts Gage EC03OC91.069...

  17. 16 CFR Figure 2 to Subpart A of... - Test Frame

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Test Frame 2 Figure 2 to Subpart A of Part 1201 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT SAFETY ACT REGULATIONS SAFETY STANDARD FOR ARCHITECTURAL GLAZING MATERIALS The Standard Pt. 1201, Subpt. A, Fig. 2 Figure 2...

  18. 16 CFR Figure 1 to Part 1511 - Pacifier Test Fixture

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 16 Commercial Practices 2 2013-01-01 2013-01-01 false Pacifier Test Fixture 1 Figure 1 to Part 1511 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS REQUIREMENTS FOR PACIFIERS Pt. 1511, Fig. 1 Figure 1 to Part 1511—Pacifier Test Fixture...

  19. 16 CFR Figure 7 to Part 1610 - Brushing Device

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 16 Commercial Practices 2 2013-01-01 2013-01-01 false Brushing Device 7 Figure 7 to Part 1610 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FLAMMABLE FABRICS ACT REGULATIONS STANDARD FOR THE FLAMMABILITY OF CLOTHING TEXTILES Pt. 1610, Fig. 7 Figure 7 to Part 1610—Brushing Device ER25MR08.006...

  20. 16 CFR Figure 1 to Part 1203 - Anatomical Planes

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 16 Commercial Practices 2 2012-01-01 2012-01-01 false Anatomical Planes 1 Figure 1 to Part 1203 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT SAFETY ACT REGULATIONS SAFETY STANDARD FOR BICYCLE HELMETS Pt. 1203, Fig. 1 Figure 1 to Part 1203—Anatomical Planes ER10MR98.001...