Evidence of Selection against Complex Mitotic-Origin Aneuploidy during Preimplantation Development.

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Rajiv C McCoy

2015-10-01

Full Text Available Whole-chromosome imbalances affect over half of early human embryos and are the leading cause of pregnancy loss. While these errors frequently arise in oocyte meiosis, many such whole-chromosome abnormalities affecting cleavage-stage embryos are the result of chromosome missegregation occurring during the initial mitotic cell divisions. The first wave of zygotic genome activation at the 4-8 cell stage results in the arrest of a large proportion of embryos, the vast majority of which contain whole-chromosome abnormalities. Thus, the full spectrum of meiotic and mitotic errors can only be detected by sampling after the initial cell divisions, but prior to this selective filter. Here, we apply 24-chromosome preimplantation genetic screening (PGS to 28,052 single-cell day-3 blastomere biopsies and 18,387 multi-cell day-5 trophectoderm biopsies from 6,366 in vitro fertilization (IVF cycles. We precisely characterize the rates and patterns of whole-chromosome abnormalities at each developmental stage and distinguish errors of meiotic and mitotic origin without embryo disaggregation, based on informative chromosomal signatures. We show that mitotic errors frequently involve multiple chromosome losses that are not biased toward maternal or paternal homologs. This outcome is characteristic of spindle abnormalities and chaotic cell division detected in previous studies. In contrast to meiotic errors, our data also show that mitotic errors are not significantly associated with maternal age. PGS patients referred due to previous IVF failure had elevated rates of mitotic error, while patients referred due to recurrent pregnancy loss had elevated rates of meiotic error, controlling for maternal age. These results support the conclusion that mitotic error is the predominant mechanism contributing to pregnancy losses occurring prior to blastocyst formation. This high-resolution view of the full spectrum of whole-chromosome abnormalities affecting early embryos

Carbamazepine induces mitotic arrest in mammalian Vero cells

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Perez Martin, J.M.; Fernandez Freire, P.; Labrador, V.; Hazen, M.J.

2008-01-01

We reported recently that the anticonvulsant drug carbamazepine, at supratherapeutic concentrations, exerts antiproliferative effects in mammalian Vero cells, but the underlying mechanism has not been elucidated. This motivates us to examine rigorously whether growth arrest was associated with structural changes in cellular organization during mitosis. In the present work, we found that exposure of the cells to carbamazepine led to an increase in mitotic index, mainly due to the sustained block at the metaphase/anaphase boundary, with the consequent inhibition of cell proliferation. Indirect immunofluorescence, using antibodies directed against spindle apparatus proteins, revealed that mitotic arrest was associated with formation of monopolar spindles, caused by impairment of centrosome separation. The final consequence of the spindle defects induced by carbamazepine, depended on the duration of cell cycle arrest. Following the time course of accumulation of metaphase and apoptotic cells during carbamazepine treatments, we observed a causative relationship between mitotic arrest and induction of cell death. Conversely, cells released from the block of metaphase by removal of the drug, continued to progress through mitosis and resume normal proliferation. Our results show that carbamazepine shares a common antiproliferative mechanism with spindle-targeted drugs and contribute to a better understanding of the cytostatic activity previously described in Vero cells. Additional studies are in progress to extend these initial findings that define a novel mode of action of carbamazepine in cultured mammalian cells

Carbamazepine induces mitotic arrest in mammalian Vero cells

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Perez Martin, J.M.; Fernandez Freire, P.; Labrador, V. [Departamento de Biologia, Facultad de Ciencias, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Hazen, M.J. [Departamento de Biologia, Facultad de Ciencias, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain)], E-mail: mariajose.hazen@uam.es

2008-01-01

We reported recently that the anticonvulsant drug carbamazepine, at supratherapeutic concentrations, exerts antiproliferative effects in mammalian Vero cells, but the underlying mechanism has not been elucidated. This motivates us to examine rigorously whether growth arrest was associated with structural changes in cellular organization during mitosis. In the present work, we found that exposure of the cells to carbamazepine led to an increase in mitotic index, mainly due to the sustained block at the metaphase/anaphase boundary, with the consequent inhibition of cell proliferation. Indirect immunofluorescence, using antibodies directed against spindle apparatus proteins, revealed that mitotic arrest was associated with formation of monopolar spindles, caused by impairment of centrosome separation. The final consequence of the spindle defects induced by carbamazepine, depended on the duration of cell cycle arrest. Following the time course of accumulation of metaphase and apoptotic cells during carbamazepine treatments, we observed a causative relationship between mitotic arrest and induction of cell death. Conversely, cells released from the block of metaphase by removal of the drug, continued to progress through mitosis and resume normal proliferation. Our results show that carbamazepine shares a common antiproliferative mechanism with spindle-targeted drugs and contribute to a better understanding of the cytostatic activity previously described in Vero cells. Additional studies are in progress to extend these initial findings that define a novel mode of action of carbamazepine in cultured mammalian cells.

A nontranscriptional role for Oct4 in the regulation of mitotic entry

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Zhao, Rui; Deibler, Richard W.; Lerou, Paul H.; Ballabeni, Andrea; Heffner, Garrett C.; Cahan, Patrick; Unternaehrer, Juli J.; Kirschner, Marc W.; Daley, George Q.

2014-01-01

Rapid progression through the cell cycle and a very short G1 phase are defining characteristics of embryonic stem cells. This distinct cell cycle is driven by a positive feedback loop involving Rb inactivation and reduced oscillations of cyclins and cyclin-dependent kinase (Cdk) activity. In this setting, we inquired how ES cells avoid the potentially deleterious consequences of premature mitotic entry. We found that the pluripotency transcription factor Oct4 (octamer-binding transcription factor 4) plays an unappreciated role in the ES cell cycle by forming a complex with cyclin–Cdk1 and inhibiting Cdk1 activation. Ectopic expression of Oct4 or a mutant lacking transcriptional activity recapitulated delayed mitotic entry in HeLa cells. Reduction of Oct4 levels in ES cells accelerated G2 progression, which led to increased chromosomal missegregation and apoptosis. Our data demonstrate an unexpected nontranscriptional function of Oct4 in the regulation of mitotic entry. PMID:25324523

Changes in Ect2 Localization Couple Actomyosin-Dependent Cell Shape Changes to Mitotic Progression

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Matthews, Helen K.; Delabre, Ulysse; Rohn, Jennifer L.; Guck, Jochen; Kunda, Patricia; Baum, Buzz

2012-01-01

Summary As they enter mitosis, animal cells undergo profound actin-dependent changes in shape to become round. Here we identify the Cdk1 substrate, Ect2, as a central regulator of mitotic rounding, thus uncovering a link between the cell-cycle machinery that drives mitotic entry and its accompanying actin remodeling. Ect2 is a RhoGEF that plays a well-established role in formation of the actomyosin contractile ring at mitotic exit, through the local activation of RhoA. We find that Ect2 first becomes active in prophase, when it is exported from the nucleus into the cytoplasm, activating RhoA to induce the formation of a mechanically stiff and rounded metaphase cortex. Then, at anaphase, binding to RacGAP1 at the spindle midzone repositions Ect2 to induce local actomyosin ring formation. Ect2 localization therefore defines the stage-specific changes in actin cortex organization critical for accurate cell division. PMID:22898780

Radiation-induced mitotic catastrophe in PARG-deficient cells

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Ame, J.Ch.; Fouquerel, E.; Dantzer, F.; De Murcia, G.; Schreiber, V. [IREBS-FRE3211 du CNRS, Universite de Strasbourg, ESBS, Bd Sebastien Brant, BP 10413, 67412 Illkirch Cedex (France); Gauthier, L.R.; Boussin, F.D. [Laboratoire de Radiopathologie/INSERM U967, CEA-DSV-IRCM, 92265 Fontenay aux Roses, Cedex 6 (France); Biard, D. [CEA-DSV-IRCM/INSERM U935, Institut A. Lwoff-CNRS, BP 8, 94801 Villejuif cedex (France)

2009-07-01

Poly(ADP-ribosyl)ation is a post-translational modification of proteins involved in the regulation of chromatin structure, DNA metabolism, cell division and cell death. Through the hydrolysis of poly(ADP-ribose) (PAR), Poly(ADP-ribose) glyco-hydrolase (PARG) has a crucial role in the control of life-and-death balance following DNA insult. Comprehension of PARG function has been hindered by the existence of many PARG isoforms encoded by a single gene and displaying various subcellular localizations. To gain insight into the function of PARG in response to irradiation, we constitutively and stably knocked down expression of PARG isoforms in HeLa cells. PARG depletion leading to PAR accumulation was not deleterious to undamaged cells and was in fact rather beneficial, because it protected cells from spontaneous single-strand breaks and telomeric abnormalities. By contrast, PARG-deficient cells showed increased radiosensitivity, caused by defects in the repair of single- and double-strand breaks and in mitotic spindle checkpoint, leading to alteration of progression of mitosis. Irradiated PARG-deficient cells displayed centrosome amplification leading to mitotic supernumerary spindle poles, and accumulated aberrant mitotic figures, which induced either polyploidy or cell death by mitotic catastrophe. Our results suggest that PARG could be a novel potential therapeutic target for radiotherapy. (authors)

Mitotic and apoptotic activity in colorectal neoplasia.

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Kohoutova, Darina; Pejchal, Jaroslav; Bures, Jan

2018-05-18

Colorectal cancer (CRC) is third most commonly diagnosed cancer worldwide. The aim of the prospective study was to evaluate mitosis and apoptosis of epithelial cells at each stage of colorectal neoplasia. A total of 61 persons were enrolled into the study: 18 patients with non-advanced colorectal adenoma (non-a-A), 13 patients with advanced colorectal adenoma (a-A), 13 patients with CRC and 17 controls: individuals with normal findings on colonoscopy. Biopsy samples were taken from pathology (patients) and healthy mucosa (patients and healthy controls). Samples were formalin-fixed paraffin-embedded and stained with haematoxylin-eosin. Mitotic and apoptotic activity were evaluated in lower and upper part of the crypts and in the superficial compartment. Apoptotic activity was also assessed using detection of activated caspase-3. In controls, mitotic activity was present in lower part of crypts, accompanied with low apoptotic activity. Mitotic and apoptotic activity decreased (to almost zero) in upper part of crypts. In superficial compartment, increase in apoptotic activity was observed. Transformation of healthy mucosa into non-a-A was associated with significant increase of mitotic activity in lower and upper part of the crypts and with significant increase of apoptotic activity in all three compartments; p colorectal neoplasia were observed. Detection of activated caspase-3 confirmed the above findings in apoptotic activity. Significant dysregulation of mitosis and apoptosis during the progression of colorectal neoplasia, corresponding with histology, was confirmed. In patients with sporadic colorectal neoplasia, healthy mucosa does not display different mitotic and apoptotic activity compared to mucosa in healthy controls and therefore adequate endoscopic/surgical removal of colorectal neoplasia is sufficient.

Mediator can regulate mitotic entry and direct periodic transcription in fission yeast.

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Banyai, Gabor; Lopez, Marcela Davila; Szilagyi, Zsolt; Gustafsson, Claes M

2014-11-01

Cdk8 is required for correct timing of mitotic progression in fission yeast. How the activity of Cdk8 is regulated is unclear, since the kinase is not activated by T-loop phosphorylation and its partner, CycC, does not oscillate. Cdk8 is, however, a component of the multiprotein Mediator complex, a conserved coregulator of eukaryotic transcription that is connected to a number of intracellular signaling pathways. We demonstrate here that other Mediator components regulate the activity of Cdk8 in vivo and thereby direct the timing of mitotic entry. Deletion of Mediator components Med12 and Med13 leads to higher cellular Cdk8 protein levels, premature phosphorylation of the Cdk8 target Fkh2, and earlier entry into mitosis. We also demonstrate that Mediator is recruited to clusters of mitotic genes in a periodic fashion and that the complex is required for the transcription of these genes. We suggest that Mediator functions as a hub for coordinated regulation of mitotic progression and cell cycle-dependent transcription. The many signaling pathways and activator proteins shown to function via Mediator may influence the timing of these cell cycle events. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Disturbed mitotic progression and genome segregation are involved in cell transformation mediated by nano-TiO2 long-term exposure

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Huang Shing; Chueh Pinju; Lin Yunwei; Shih Tungsheng; Chuang Showmei

2009-01-01

Titanium dioxide (TiO2) nano-particles (< 100 nm in diameter) have been of interest in a wide range of applications, such as in cosmetics and pharmaceuticals because of their low toxicity. However, recent studies have shown that TiO2 nano-particles (nano-TiO2) induce cytotoxicity and genotoxicity in various lines of cultured cells as well as tumorigenesis in animal models. The biological roles of nano-TiO2 are shown to be controversial and no comprehensive study paradigm has been developed to investigate their molecular mechanisms. In this study, we showed that short-term exposure to nano-TiO2 enhanced cell proliferation, survival, ERK signaling activation and ROS production in cultured fibroblast cells. Moreover, long-term exposure to nano-TiO2 not only increased cell survival and growth on soft agar but also the numbers of multinucleated cells and micronucleus (MN) as suggested in confocal microscopy analysis. Cell cycle phase analysis showed G2/M delay and slower cell division in long-term exposed cells. Most importantly, long-term TiO2 exposure remarkably affected mitotic progression at anaphase and telophase leading to aberrant multipolar spindles and chromatin alignment/segregation. Moreover, PLK1 was demonstrated as the target for nano-TiO2 in the regulation of mitotic progression and exit. Notably, a higher fraction of sub-G1 phase population appeared in TiO2-exposed cells after releasing from G2/M synchronization. Our results demonstrate that long-term exposure to nano-TiO2 disturbs cell cycle progression and duplicated genome segregation, leading to chromosomal instability and cell transformation.

Down-regulation of tricarboxylic acid (TCA) cycle genes blocks progression through the first mitotic division in Caenorhabditis elegans embryos.

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Rahman, Mohammad M; Rosu, Simona; Joseph-Strauss, Daphna; Cohen-Fix, Orna

2014-02-18

The cell cycle is a highly regulated process that enables the accurate transmission of chromosomes to daughter cells. Here we uncover a previously unknown link between the tricarboxylic acid (TCA) cycle and cell cycle progression in the Caenorhabditis elegans early embryo. We found that down-regulation of TCA cycle components, including citrate synthase, malate dehydrogenase, and aconitase, resulted in a one-cell stage arrest before entry into mitosis: pronuclear meeting occurred normally, but nuclear envelope breakdown, centrosome separation, and chromosome condensation did not take place. Mitotic entry is controlled by the cyclin B-cyclin-dependent kinase 1 (Cdk1) complex, and the inhibitory phosphorylation of Cdk1 must be removed in order for the complex to be active. We found that following down-regulation of the TCA cycle, cyclin B levels were normal but CDK-1 remained inhibitory-phosphorylated in one-cell stage-arrested embryos, indicative of a G2-like arrest. Moreover, this was not due to an indirect effect caused by checkpoint activation by DNA damage or replication defects. These observations suggest that CDK-1 activation in the C. elegans one-cell embryo is sensitive to the metabolic state of the cell, and that down-regulation of the TCA cycle prevents the removal of CDK-1 inhibitory phosphorylation. The TCA cycle was previously shown to be necessary for the development of the early embryo in mammals, but the molecular processes affected were not known. Our study demonstrates a link between the TCA cycle and a specific cell cycle transition in the one-cell stage embryo.

Co-delivery of paclitaxel and cetuximab by nanodiamond enhances mitotic catastrophe and tumor inhibition.

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Lin, Yu-Wei; Raj, Emmanuel Naveen; Liao, Wei-Siang; Lin, Johnson; Liu, Kuang-Kai; Chen, Ting-Hua; Cheng, Hsiao-Chun; Wang, Chi-Ching; Li, Lily Yi; Chen, Chinpiao; Chao, Jui-I

2017-08-29

The poor intracellular uptake and non-specific binding of anticancer drugs into cancer cells are the bottlenecks in cancer therapy. Nanocarrier platforms provide the opportunities to improve the drug efficacy. Here we show a carbon-based nanomaterial nanodiamond (ND) that carried paclitaxel (PTX), a microtubule inhibitor, and cetuximab (Cet), a specific monoclonal antibody against epidermal growth factor receptor (EGFR), inducing mitotic catastrophe and tumor inhibition in human colorectal cancer (CRC). ND-PTX blocked the mitotic progression, chromosomal separation, and induced apoptosis in the CRC cells; however, NDs did not induce these effects. Conjugation of ND-PTX with Cet (ND-PTX-Cet) was specifically binding to the EGFR-positive CRC cells and enhanced the mitotic catastrophe and apoptosis induction. Besides, ND-PTX-Cet markedly decreased tumor size in the xenograft EGFR-expressed human CRC tumors of nude mice. Moreover, ND-PTX-Cet induced the mitotic marker protein phospho-histone 3 (Ser10) and apoptotic protein active-caspase 3 for mitotic catastrophe and apoptosis. Taken together, this study demonstrated that the co-delivery of PTX and Cet by ND enhanced the effects of mitotic catastrophe and apoptosis in vitro and in vivo, which may be applied in the human CRC therapy.

The structure of the mitotic spindle and nucleolus during mitosis in the amebo-flagellate Naegleria.

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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.

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

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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

Evidence of activity-specific, radial organization of mitotic chromosomes in Drosophila.

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Yuri G Strukov

2011-01-01

Full Text Available The organization and the mechanisms of condensation of mitotic chromosomes remain unsolved despite many decades of efforts. The lack of resolution, tight compaction, and the absence of function-specific chromatin labels have been the key technical obstacles. The correlation between DNA sequence composition and its contribution to the chromosome-scale structure has been suggested before; it is unclear though if all DNA sequences equally participate in intra- or inter-chromatin or DNA-protein interactions that lead to formation of mitotic chromosomes and if their mitotic positions are reproduced radially. Using high-resolution fluorescence microscopy of live or minimally perturbed, fixed chromosomes in Drosophila embryonic cultures or tissues expressing MSL3-GFP fusion protein, we studied positioning of specific MSL3-binding sites. Actively transcribed, dosage compensated Drosophila genes are distributed along the euchromatic arm of the male X chromosome. Several novel features of mitotic chromosomes have been observed. MSL3-GFP is always found at the periphery of mitotic chromosomes, suggesting that active, dosage compensated genes are also found at the periphery of mitotic chromosomes. Furthermore, radial distribution of chromatin loci on mitotic chromosomes was found to be correlated with their functional activity as judged by core histone modifications. Histone modifications specific to active chromatin were found peripheral with respect to silent chromatin. MSL3-GFP-labeled chromatin loci become peripheral starting in late prophase. In early prophase, dosage compensated chromatin regions traverse the entire width of chromosomes. These findings suggest large-scale internal rearrangements within chromosomes during the prophase condensation step, arguing against consecutive coiling models. Our results suggest that the organization of mitotic chromosomes is reproducible not only longitudinally, as demonstrated by chromosome-specific banding

Inhibition of the mitotic exit network in response to damaged telomeres.

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Mauricio Valerio-Santiago

Full Text Available When chromosomal DNA is damaged, progression through the cell cycle is halted to provide the cells with time to repair the genetic material before it is distributed between the mother and daughter cells. In Saccharomyces cerevisiae, this cell cycle arrest occurs at the G2/M transition. However, it is also necessary to restrain exit from mitosis by maintaining Bfa1-Bub2, the inhibitor of the Mitotic Exit Network (MEN, in an active state. While the role of Bfa1 and Bub2 in the inhibition of mitotic exit when the spindle is not properly aligned and the spindle position checkpoint is activated has been extensively studied, the mechanism by which these proteins prevent MEN function after DNA damage is still unclear. Here, we propose that the inhibition of the MEN is specifically required when telomeres are damaged but it is not necessary to face all types of chromosomal DNA damage, which is in agreement with previous data in mammals suggesting the existence of a putative telomere-specific DNA damage response that inhibits mitotic exit. Furthermore, we demonstrate that the mechanism of MEN inhibition when telomeres are damaged relies on the Rad53-dependent inhibition of Bfa1 phosphorylation by the Polo-like kinase Cdc5, establishing a new key role of this kinase in regulating cell cycle progression.

The reduction of radiation-induced mitotic delay by caffeine: a test of the cyclic AMP hypothesis

International Nuclear Information System (INIS)

Oleinick, N.L.; Brewer, E.N.; Rustad, R.C.

1978-01-01

A study has been made of the reduction in γ-radiation-induced mitotic delay by caffeine in the naturally-synchronous plasmodial slime mould. Physarum polycephalum during late G 2 and early prophase, and the results compared with those obtained with other compounds of similar structure and/or physiological function. The reduction of radiation-induced mitotic delay was related to increasing concentrations of caffeine over at least two orders of magnitude. Pre-irradiation treatment with caffeine had no detectable effect. Caffeine had to be present for most, if not all, of the post-irradiation pre-mitotic period. Other chemicals which are reported to inhibit cyclic AMP phosphodiesterase either reduce or increase radiation-induced mitotic delay. The results therefore indicate that the reduction of mitotic delay by caffeine is not a result of altered cyclic AMP levels. (UK)

The Drosophila Microtubule-Associated Protein Mars Stabilizes Mitotic Spindles by Crosslinking Microtubules through Its N-Terminal Region

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Zhang, Gang; Beati, Hamze; Nilsson, Jakob; Wodarz, Andreas

2013-01-01

Correct segregation of genetic material relies on proper assembly and maintenance of the mitotic spindle. How the highly dynamic microtubules (MTs) are maintained in stable mitotic spindles is a key question to be answered. Motor and non-motor microtubule associated proteins (MAPs) have been reported to stabilize the dynamic spindle through crosslinking adjacent MTs. Mars, a novel MAP, is essential for the early development of Drosophila embryos. Previous studies showed that Mars is required for maintaining an intact mitotic spindle but did not provide a molecular mechanism for this function. Here we show that Mars is able to stabilize the mitotic spindle in vivo. Both in vivo and in vitro data reveal that the N-terminal region of Mars functions in the stabilization of the mitotic spindle by crosslinking adjacent MTs. PMID:23593258

The Drosophila microtubule-associated protein mars stabilizes mitotic spindles by crosslinking microtubules through its N-terminal region.

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Gang Zhang

Full Text Available Correct segregation of genetic material relies on proper assembly and maintenance of the mitotic spindle. How the highly dynamic microtubules (MTs are maintained in stable mitotic spindles is a key question to be answered. Motor and non-motor microtubule associated proteins (MAPs have been reported to stabilize the dynamic spindle through crosslinking adjacent MTs. Mars, a novel MAP, is essential for the early development of Drosophila embryos. Previous studies showed that Mars is required for maintaining an intact mitotic spindle but did not provide a molecular mechanism for this function. Here we show that Mars is able to stabilize the mitotic spindle in vivo. Both in vivo and in vitro data reveal that the N-terminal region of Mars functions in the stabilization of the mitotic spindle by crosslinking adjacent MTs.

The Drosophila microtubule-associated protein mars stabilizes mitotic spindles by crosslinking microtubules through its N-terminal region.

Science.gov (United States)

Zhang, Gang; Beati, Hamze; Nilsson, Jakob; Wodarz, Andreas

2013-01-01

Correct segregation of genetic material relies on proper assembly and maintenance of the mitotic spindle. How the highly dynamic microtubules (MTs) are maintained in stable mitotic spindles is a key question to be answered. Motor and non-motor microtubule associated proteins (MAPs) have been reported to stabilize the dynamic spindle through crosslinking adjacent MTs. Mars, a novel MAP, is essential for the early development of Drosophila embryos. Previous studies showed that Mars is required for maintaining an intact mitotic spindle but did not provide a molecular mechanism for this function. Here we show that Mars is able to stabilize the mitotic spindle in vivo. Both in vivo and in vitro data reveal that the N-terminal region of Mars functions in the stabilization of the mitotic spindle by crosslinking adjacent MTs.

Histone phosphorylation during radiation-induced mitotic delay in synchronous plasmodia of Physarum polycephalum

International Nuclear Information System (INIS)

Brewer, E.N.; Oleinick, N.L.

1980-01-01

Using the nearly perfect synchrony of the mitotic stages in Physarum plasmodia, and making use of 32 P as a tracer, studies were made to define the time course of histone phosphorylation during the late G2 and prophase and the alterations in that time course accompanying radiation-induced mitotic delay. Histone H1 was phosphorylated throughout the last 2-3 hours of the mitotic cycle coincident with the early stages of chromosome condensation. H1 phosphorylation appeared to be reduced in irradiated plasmodia. It is postulated that a longer time period, i.e. the mitotic delay, may be required to obtain the same eventual level of H1-phosphate. In normal cultures, nucleosome core histones were phosphorylated late in G2 and prophase, the peak corresponding closely with the γ-transition point. In irradiated plasmodia, phosphorylation of the core histones had an extended time course similar to H1. (U.K.)

Smurf2 as a novel mitotic regulator: From the spindle assembly checkpoint to tumorigenesis

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Moore Finola E

2009-07-01

Full Text Available Abstract The execution of the mitotic program with high fidelity is dependent upon precise spatiotemporal regulation of posttranslational protein modifications. For example, the timely polyubiquitination of critical mitotic regulators by Anaphase Promoting Complex/Cyclosome (APC/C is essential for the metaphase to anaphase transition and mitotic exit. The spindle assembly checkpoint prevents unscheduled activity of APC/C-Cdc20 in early mitosis, allowing bipolar attachment of kinetochores to mitotic spindle and facilitating equal segregation of sister chromatids. The critical effector of the spindle checkpoint, Mitotic arrest deficient 2 (Mad2, is recruited to unattached kinetochores forming a complex with other regulatory proteins to efficiently and cooperatively inhibit APC/C-Cdc20. A weakened and/or dysfunctional spindle checkpoint has been linked to the development of genomic instability in both cell culture and animal models, and evidence suggests that aberrant regulation of the spindle checkpoint plays a critical role in human carcinogenesis. Recent studies have illuminated a network of both degradative and non-degradative ubiquitination events that regulate the metaphase to anaphase transition and mitotic exit. Within this context, our recent work showed that the HECT (Homologous to E6-AP C-terminus-family E3 ligase Smurf2 (Smad specific ubiquitin regulatory factor 2, known as a negative regulator of transforming growth factor-beta (TGF-β signaling, is required for a functional spindle checkpoint by promoting the functional localization and stability of Mad2. Here we discuss putative models explaining the role of Smurf2 as a new regulator in the spindle checkpoint. The dynamic mitotic localization of Smurf2 to the centrosome and other critical mitotic structures provides implications about mitotic checkpoint control dependent on various ubiquitination events. Finally, deregulated Smurf2 activity may contribute to carcinogenesis by

The effects of pulse cycloheximide treatments on the light-induced recovery of mitotic divisions in antheridial filaments of Chara vulgaris

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Maria Kwiatkowska

2014-01-01

Full Text Available Within the proliferative period of spermatogenesis in Chara vulgaris, the progression throughout successive cell divisions in antheridial filaments is greatly influenced by changes in photoperiodic conditions. The extended (4-day period of total darkness brings about cell cycle arrest in the early G2 phase. The recovery of mitosis requires about 20 hours of exposition to light. In the present study, a series of 8 pulse incubations of plants in cycloheximide (Cx; 2.5 mg/I, 2.5 h each pulse were performed within the period elapsing till the resumption of mitotic divisions. Depending on the time of treatment, the effects induced by Cx vary considerably. Within the first 10 hs of exposition to light, incubations with Cx result in the delays of mitoses; within the period between the 10th and the 17th h, mitotic divisions become blocked, and, following the 17.5 h of light-induced recovery, no influence of Cx is noticed on mitotic activity, as compared with the untreaed control plants. The obtained results provide a starting point for the characteristic of proteins synthesized during the G2 phase and a preliminary study on those mechanisms, which become engaged in the regulation of the G1-deficient cell cycle evidenced in antheridial filaments of Chara.

Comparative effects of ionizing radiation on cycle time and mitotic duration. A time-lapse cinematography study

International Nuclear Information System (INIS)

D'Hooghe, M.C.; Hemon, D.; Valleron, A.J.; Malaise, E.P.

1980-01-01

The effects of 60 Co γ rays on the length of the intermitotic period, the duration of mitosis, and the division probability of EMT6 cells have been studied in vitro using time-lapse cinematography. Irradiation increases the duration of the mitosis and of the cycle in comparable proportions: both parameters are practically doubled by a dose of 10 Gy. When daughters of irradiated cells die, the mitotic delay and lengthening of mitosis of their mother cells are longer than average. Mitotic delay and lengthening of mitosis depend on the age of cells at the moment of irradiation. The mitotic delay increases progressively when cells are irradiated during the first 8 h of their cycle (i.e., before the transition point), whereas mitosis is slightly prolonged. On the other hand, when the cells are irradiated after this transition point the mitotic delay decreases markedly, whereas the lengthening of mitosis increases sharply. These results tend to indicate that two different mechanisms are responsible for mitotic delay and prolongation of mitosis observed after irradiation

Comparative effects of ionizing radiation on cycle time and mitotic duration. A time-lapse cinematography study

Energy Technology Data Exchange (ETDEWEB)

D' Hooghe, M.C. (Institut de Recherches sur le Cancer, Lille, France); Hemon, D.; Valleron, A.J.; Malaise, E.P.

1980-03-01

The effects of /sup 60/Co ..gamma.. rays on the length of the intermitotic period, the duration of mitosis, and the division probability of EMT6 cells have been studied in vitro using time-lapse cinematography. Irradiation increases the duration of the mitosis and of the cycle in comparable proportions: both parameters are practically doubled by a dose of 10 Gy. When daughters of irradiated cells die, the mitotic delay and lengthening of mitosis of their mother cells are longer than average. Mitotic delay and lengthening of mitosis depend on the age of cells at the moment of irradiation. The mitotic delay increases progressively when cells are irradiated during the first 8 h of their cycle (i.e., before the transition point), whereas mitosis is slightly prolonged. On the other hand, when the cells are irradiated after this transition point the mitotic delay decreases markedly, whereas the lengthening of mitosis increases sharply. These results tend to indicate that two different mechanisms are responsible for mitotic delay and prolongation of mitosis observed after irradiation.

New mitotic regulators released from chromatin

Directory of Open Access Journals (Sweden)

Hideki eYokoyama

2013-12-01

Full Text Available Faithful action of the mitotic spindle segregates duplicated chromosomes into daughter cells. Perturbations of this process result in chromosome mis-segregation, leading to chromosomal instability and cancer development. Chromosomes are not simply passengers segregated by spindle microtubules but rather play a major active role in spindle assembly. The GTP bound form of the Ran GTPase (RanGTP, produced around chromosomes, locally activates spindle assembly factors. Recent studies have uncovered that chromosomes organize mitosis beyond spindle formation. They distinctly regulate other mitotic events, such as spindle maintenance in anaphase, which is essential for chromosome segregation. Furthermore, the direct function of chromosomes is not only to produce RanGTP but, in addition, to release key mitotic regulators from chromatin. Chromatin-remodeling factors and nuclear pore complex proteins, which have established functions on chromatin in interphase, dissociate from mitotic chromatin and function in spindle assembly or maintenance. Thus, chromosomes actively organize their own segregation using chromatin-releasing mitotic regulators as well as RanGTP.

Influence of novobiocin on mitotic events and radiation-induced G2-arrest

International Nuclear Information System (INIS)

Rowley, R.

1987-01-01

Novobiocin was used in CHO cells to test for an involvement of topoisomerase II activity in; 1) the induction of, and recovery from, radiation-induced G 2 -arrest and 2) progression through mitosis. Novobiocin blocked recovery from G 2 -arrest with a concentration dependency which suggested that this effect resulted from protein synthesis inhibition. Novobiocin alone, at concentrations above 500 μgml, blocked cell progression in early mitosis. The transition point was distinct from that of protein and RNA synthesis inhibitors and was the only arrest point in mitosis. A similar block was imposed by coumermycin. While this may indicate a requirement for topoisomerase II activity during chromosome condensation, it was also associated with inhibition of histone phosphorylation. Histone H3 phosphorylation is believed to be necessary for chromosome condensation and, when inhibited by novobiocin, correlates with a block in premature chromatin condensation in tsBN2 cells. The authors' data thus unite these two findings, provide an opportunity to analyse the temporal relationship between histone phosphorylation and mitotic events and suggest that topological reorganization of the chromatin is not involved in radiation-induced G 2 arrest

Delayed cell death associated with mitotic catastrophe in γ-irradiated stem-like glioma cells

International Nuclear Information System (INIS)

Firat, Elke; Gaedicke, Simone; Tsurumi, Chizuko; Esser, Norbert; Weyerbrock, Astrid; Niedermann, Gabriele

2011-01-01

Stem-like tumor cells are regarded as highly resistant to ionizing radiation (IR). Previous studies have focused on apoptosis early after irradiation, and the apoptosis resistance observed has been attributed to reduced DNA damage or enhanced DNA repair compared to non-stem tumor cells. Here, early and late radioresponse of patient-derived stem-like glioma cells (SLGCs) and differentiated cells directly derived from them were examined for cell death mode and the influence of stem cell-specific growth factors. Primary SLGCs were propagated in serum-free medium with the stem-cell mitogens epidermal growth factor (EGF) and fibroblast growth factor-2 (FGF-2). Differentiation was induced by serum-containing medium without EGF and FGF. Radiation sensitivity was evaluated by assessing proliferation, clonogenic survival, apoptosis, and mitotic catastrophe. DNA damage-associated γH2AX as well as p53 and p21 expression were determined by Western blots. SLGCs failed to apoptose in the first 4 days after irradiation even at high single doses up to 10 Gy, but we observed substantial cell death later than 4 days postirradiation in 3 of 6 SLGC lines treated with 5 or 10 Gy. This delayed cell death was observed in 3 of the 4 SLGC lines with nonfunctional p53, was associated with mitotic catastrophe and occurred via apoptosis. The early apoptosis resistance of the SLGCs was associated with lower γH2AX compared to differentiated cells, but we found that the stem-cell culture cytokines EGF plus FGF-2 strongly reduce γH2AX levels. Nonetheless, in two p53-deficient SLGC lines examined γIR-induced apoptosis even correlated with EGF/FGF-induced proliferation and mitotic catastrophe. In a line containing CD133-positive and -negative stem-like cells, the CD133-positive cells proliferated faster and underwent more γIR-induced mitotic catastrophe. Our results suggest the importance of delayed apoptosis, associated mitotic catastrophe, and cellular proliferation for γIR-induced death of

Mitotic effects of monochromatic ultraviolet radiation at 225, 265, and 280 nm on eleven stages of the cell cycle of the grasshopper neuroblast in culture. II. Changes in progression rate and cell sequence between the stage irradiated and nuclear membrane breakdown

International Nuclear Information System (INIS)

Carlson, J.G.

1976-01-01

Portions of embryos of the grasshopper, Chortophaga viridifasciata (DeGeer), were cultured in hanging drops under quartz cover slips. Immediately after exposure to 225, 265, or 280 nm radiation, microscope observations at 38 0 C were begun. The morphologically identified stage and the time after treatment of selected neuroblasts were recorded at short-time intervals until prometaphase was reached. Mitotic retardation induced by irradiation of prereplication stages (metaphase, anaphase, or early telophase) or S phase (middle or late telophase, interphase, or very early prophase) is greatest in postreplication stages (early, middle, and late prophase) and absent or minimal in stages morphologically identified as parts of S phase. Ultraviolet irradiation superimposes on the normal diversity of progression rates an additional variation factor, so that cells do not necessarily reach prometaphase in the order of their sequence at the time of treatment. This suggests the need for caution in ascribing particular radiosensitivities to substages of limited duration on the basis of the order in which they attain a subsequent stage

Micromechanics of human mitotic chromosomes

International Nuclear Information System (INIS)

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

2011-01-01

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

Quantitative phosphoproteomics reveals new roles for the protein phosphatase PP6 in mitotic cells.

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Rusin, Scott F; Schlosser, Kate A; Adamo, Mark E; Kettenbach, Arminja N

2015-10-13

Protein phosphorylation is an important regulatory mechanism controlling mitotic progression. Protein phosphatase 6 (PP6) is an essential enzyme with conserved roles in chromosome segregation and spindle assembly from yeast to humans. We applied a baculovirus-mediated gene silencing approach to deplete HeLa cells of the catalytic subunit of PP6 (PP6c) and analyzed changes in the phosphoproteome and proteome in mitotic cells by quantitative mass spectrometry-based proteomics. We identified 408 phosphopeptides on 272 proteins that increased and 298 phosphopeptides on 220 proteins that decreased in phosphorylation upon PP6c depletion in mitotic cells. Motif analysis of the phosphorylated sites combined with bioinformatics pathway analysis revealed previously unknown PP6c-dependent regulatory pathways. Biochemical assays demonstrated that PP6c opposed casein kinase 2-dependent phosphorylation of the condensin I subunit NCAP-G, and cellular analysis showed that depletion of PP6c resulted in defects in chromosome condensation and segregation in anaphase, consistent with dysregulation of condensin I function in the absence of PP6 activity. Copyright © 2015, American Association for the Advancement of Science.

Conditional mutation of Smc5 in mouse embryonic stem cells perturbs condensin localization and mitotic progression.

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Pryzhkova, Marina V; Jordan, Philip W

2016-04-15

Correct duplication of stem cell genetic material and its appropriate segregation into daughter cells are requisites for tissue, organ and organism homeostasis. Disruption of stem cell genomic integrity can lead to developmental abnormalities and cancer. Roles of the Smc5/6 structural maintenance of chromosomes complex in pluripotent stem cell genome maintenance have not been investigated, despite its important roles in DNA synthesis, DNA repair and chromosome segregation as evaluated in other model systems. Using mouse embryonic stem cells (mESCs) with a conditional knockout allele of Smc5, we showed that Smc5 protein depletion resulted in destabilization of the Smc5/6 complex, accumulation of cells in G2 phase of the cell cycle and apoptosis. Detailed assessment of mitotic mESCs revealed abnormal condensin distribution and perturbed chromosome segregation, accompanied by irregular spindle morphology, lagging chromosomes and DNA bridges. Mutation of Smc5 resulted in retention of Aurora B kinase and enrichment of condensin on chromosome arms. Furthermore, we observed reduced levels of Polo-like kinase 1 at kinetochores during mitosis. Our study reveals crucial requirements of the Smc5/6 complex during cell cycle progression and for stem cell genome maintenance. © 2016. Published by The Company of Biologists Ltd.

Prediction of X-ray induced mitotic delay and recovery of G2 cells

International Nuclear Information System (INIS)

Easton, D.M.; Schneiderman, M.H.

1987-01-01

A mathematical model is presented that predicts the delay of mitosis caused by X-irradiation of an asynchronous, exponentially growing cell culture. In the model, based on Gompertz kinetics, the driving function to generate the curves is a simple exponential decay expression. For the delayed mitotic progress curves, this function characterizes the distribution of the time required for cells to enter mitosis. (author)

LOX is a novel mitotic spindle-associated protein essential for mitosis.

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Boufraqech, Myriem; Wei, Darmood; Weyemi, Urbain; Zhang, Lisa; Quezado, Martha; Kalab, Petr; Kebebew, Electron

2016-05-17

LOX regulates cancer progression in a variety of human malignancies. It is overexpressed in aggressive cancers and higher expression of LOX is associated with higher cancer mortality. Here, we report a new function of LOX in mitosis. We show that LOX co-localizes to mitotic spindles from metaphase to telophase, and p-H3(Ser10)-positive cells harbor strong LOX staining. Further, purification of mitotic spindles from synchronized cells show that LOX fails to bind to microtubules in the presence of nocodazole, whereas paclitaxel treated samples showed enrichment in LOX expression, suggesting that LOX binds to stabilized microtubules. LOX knockdown leads to G2/M phase arrest; reduced p-H3(Ser10), cyclin B1, CDK1, and Aurora B. Moreover, LOX knockdown significantly increased sensitivity of cancer cells to chemotherapeutic agents that target microtubules. Our findings suggest that LOX has a role in cancer cell mitosis and may be targeted to enhance the activity of microtubule inhibitors for cancer therapy.

Detection of mitotic figures in thin melanomas--immunohistochemistry does not replace the careful search for mitotic figures in hematoxylin-eosin stain.

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Ottmann, Karl; Tronnier, Michael; Mitteldorf, Christina

2015-10-01

The mitotic rate is an important prognostic criterion in patients with thin melanoma ≤ 1 mm. The aim of this study was to investigate the reproducibility of the mitotic rate in thin melanoma in hematoxylin-eosin (H&E) stain and compare it with the detection of mitotic figures by immunohistochemistry. The number of mitoses stated in the routine diagnostic report in 190 pT1 melanomas was compared with the number gained from re-evaluation of H&E sections and the number detected after staining with the mitotic marker, phosphohistone H3 (PHH3). Two different approaches were used for choosing the "hot spot" for evaluation (dermal vs epidermal/dermal). Comparing routine H&E-stained slides with re-evaluation slides, the number of mitotic figures was slightly variable. However, findings did not result in a change of the tumor stage. In 34% of the tumors with dermal mitotic figures on H&E, mitoses could not be found in the corresponding PHH3 slide anymore. In 4% of the cases, stage relevant mitoses could only be found by PHH3 immunohistochemistry. This is a single center study. Immunohistochemical staining for mitotic figures does not replace a careful evaluation of H&E-stained slides. Immunohistochemical detection of mitosis is only an additional tool; the time-saving effect is therefore negligible. Copyright © 2015 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.

Mitotic phosphorylation of VCIP135 blocks p97ATPase-mediated Golgi membrane fusion

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Totsukawa, Go; Matsuo, Ayaka; Kubota, Ayano; Taguchi, Yuya; Kondo, Hisao, E-mail: hk228@med.kyushu-u.ac.jp

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.

DNA lesions induced by replication stress trigger mitotic aberration and tetraploidy development.

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Yosuke Ichijima

Full Text Available During tumorigenesis, cells acquire immortality in association with the development of genomic instability. However, it is still elusive how genomic instability spontaneously generates during the process of tumorigenesis. Here, we show that precancerous DNA lesions induced by oncogene acceleration, which induce situations identical to the initial stages of cancer development, trigger tetraploidy/aneuploidy generation in association with mitotic aberration. Although oncogene acceleration primarily induces DNA replication stress and the resulting lesions in the S phase, these lesions are carried over into the M phase and cause cytokinesis failure and genomic instability. Unlike directly induced DNA double-strand breaks, DNA replication stress-associated lesions are cryptogenic and pass through cell-cycle checkpoints due to limited and ineffective activation of checkpoint factors. Furthermore, since damaged M-phase cells still progress in mitotic steps, these cells result in chromosomal mis-segregation, cytokinesis failure and the resulting tetraploidy generation. Thus, our results reveal a process of genomic instability generation triggered by precancerous DNA replication stress.

Interlinked bistable mechanisms generate robust mitotic transitions.

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Hutter, Lukas H; Rata, Scott; Hochegger, Helfrid; Novák, Béla

2017-10-18

The transitions between phases of the cell cycle have evolved to be robust and switch-like, which ensures temporal separation of DNA replication, sister chromatid separation, and cell division. Mathematical models describing the biochemical interaction networks of cell cycle regulators attribute these properties to underlying bistable switches, which inherently generate robust, switch-like, and irreversible transitions between states. We have recently presented new mathematical models for two control systems that regulate crucial transitions in the cell cycle: mitotic entry and exit, 1 and the mitotic checkpoint. 2 Each of the two control systems is characterized by two interlinked bistable switches. In the case of mitotic checkpoint control, these switches are mutually activating, whereas in the case of the mitotic entry/exit network, the switches are mutually inhibiting. In this Perspective we describe the qualitative features of these regulatory motifs and show that having two interlinked bistable mechanisms further enhances robustness and irreversibility. We speculate that these network motifs also underlie other cell cycle transitions and cellular transitions between distinct biochemical states.

ATYPICAL MITOTIC FIGURES AND THE MITOTIC INDEX IN CERVICAL INTRAEPITHELIAL NEOPLASIA

NARCIS (Netherlands)

VANLEEUWEN, AM; PIETERS, WJLM; HOLLEMA, H; BURGER, MPM

1995-01-01

We surveyed cervical intraepithelial neoplasia (CIN) to quantify the proliferation rate and the presence of normal and atypical mitotic figures. In the cervical tissue specimens of 127 women with CIN, the area with the highest cell proliferation was identified and, at that site, the proliferation

The role of p53 in the response to mitotic spindle damage

International Nuclear Information System (INIS)

Meek, D.W.

2000-01-01

The p53 tumour suppressor protein has defined roles in G1/S and G2/M cell cycle checkpoint in response to a range of cellular stresses including DNA damage, dominant oncogene expression, hypoxia, metabolic changes and viral infection. In addition to these responses, p53 can also be activated when damage occurs to the mitotic spindle. Initially, spindle damage activates a p53-independent checkpoint which functions at the metaphase-anaphase transition and prevents cells from progressing through mitosis until the completion of spindle formation. Cells eventually escape from this block (a process termed 'mitotic slippage'), and an aberrant mitosis ensues in which sister chromatids fail to segregate properly. After a delay period, p53 responds to this mitotic failure by instituting a G1-like growth arrest, with an intact nucleus containing 4N DNA, but without the cells undergoing division. Cells lacking wild-type p53 are still able to arrest transiently at mitosis, and also fail to undergo division, underscoring that the delay in mitosis is p53-independent. However, these cells are not prevented from re-entering the cell cycle and can reduplicate their DNA unchecked, leading to polyploidy. Additionally, p53-null cells which experience spindle failure often show the appearance of micronuclei arising from poorly segregated chromosomes which have de-condensed and been enclosed in a nuclear envelope. The ability of p53 to prevent their formation suggests an additional G2 involvement which prevents nuclear breakdown prior to mitosis. The molecular mechanism by which p53 is able to sense mitotic failure is still unknown, but may be linked to the ability of p53 to regulate duplication of the centrosome, the organelle which nucleates spindle formation. (authors)

The small molecule inhibitor YK-4-279 disrupts mitotic progression of neuroblastoma cells, overcomes drug resistance and synergizes with inhibitors of mitosis.

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Kollareddy, Madhu; Sherrard, Alice; Park, Ji Hyun; Szemes, Marianna; Gallacher, Kelli; Melegh, Zsombor; Oltean, Sebastian; Michaelis, Martin; Cinatl, Jindrich; Kaidi, Abderrahmane; Malik, Karim

2017-09-10

Neuroblastoma is a biologically and clinically heterogeneous pediatric malignancy that includes a high-risk subset for which new therapeutic agents are urgently required. As well as MYCN amplification, activating point mutations of ALK and NRAS are associated with high-risk and relapsing neuroblastoma. As both ALK and RAS signal through the MEK/ERK pathway, we sought to evaluate two previously reported inhibitors of ETS-related transcription factors, which are transcriptional mediators of the Ras-MEK/ERK pathway in other cancers. Here we show that YK-4-279 suppressed growth and triggered apoptosis in nine neuroblastoma cell lines, while BRD32048, another ETV1 inhibitor, was ineffective. These results suggest that YK-4-279 acts independently of ETS-related transcription factors. Further analysis reveals that YK-4-279 induces mitotic arrest in prometaphase, resulting in subsequent cell death. Mechanistically, we show that YK-4-279 inhibits the formation of kinetochore microtubules, with treated cells showing a broad range of abnormalities including multipolar, fragmented and unseparated spindles, together leading to disrupted progression through mitosis. Notably, YK-4-279 does not affect microtubule acetylation, unlike the conventional mitotic poisons paclitaxel and vincristine. Consistent with this, we demonstrate that YK-4-279 overcomes vincristine-induced resistance in two neuroblastoma cell-line models. Furthermore, combinations of YK-4-279 with vincristine, paclitaxel or the Aurora kinase A inhibitor MLN8237/Alisertib show strong synergy, particularly at low doses. Thus, YK-4-279 could potentially be used as a single-agent or in combination therapies for the treatment of high-risk and relapsing neuroblastoma, as well as other cancers. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

The Progression and Early detection of Subclinical Atherosclerosis (PESA) study

DEFF Research Database (Denmark)

Fernández-Ortiz, Antonio; Jiménez-Borreguero, L Jesús; Peñalvo, José L

2013-01-01

The presence of subclinical atherosclerosis is a likely predictor of cardiovascular events; however, factors associated with the early stages and progression of atherosclerosis are poorly defined.......The presence of subclinical atherosclerosis is a likely predictor of cardiovascular events; however, factors associated with the early stages and progression of atherosclerosis are poorly defined....

Diverse mitotic functions of the cytoskeletal cross-linking protein Shortstop suggest a role in Dynein/Dynactin activity.

Science.gov (United States)

Dewey, Evan B; Johnston, Christopher A

2017-09-15

Proper assembly and orientation of the bipolar mitotic spindle is critical to the fidelity of cell division. Mitotic precision fundamentally contributes to cell fate specification, tissue development and homeostasis, and chromosome distribution within daughter cells. Defects in these events are thought to contribute to several human diseases. The underlying mechanisms that function in spindle morphogenesis and positioning remain incompletely defined, however. Here we describe diverse roles for the actin-microtubule cross-linker Shortstop (Shot) in mitotic spindle function in Drosophila Shot localizes to mitotic spindle poles, and its knockdown results in an unfocused spindle pole morphology and a disruption of proper spindle orientation. Loss of Shot also leads to chromosome congression defects, cell cycle progression delay, and defective chromosome segregation during anaphase. These mitotic errors trigger apoptosis in Drosophila epithelial tissue, and blocking this apoptotic response results in a marked induction of the epithelial-mesenchymal transition marker MMP-1. The actin-binding domain of Shot directly interacts with Actin-related protein-1 (Arp-1), a key component of the Dynein/Dynactin complex. Knockdown of Arp-1 phenocopies Shot loss universally, whereas chemical disruption of F-actin does so selectively. Our work highlights novel roles for Shot in mitosis and suggests a mechanism involving Dynein/Dynactin activation. © 2017 Dewey and Johnston. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

Insulin growth factors regulate the mitotic cycle in cultured rat sympathetic neuroblasts

International Nuclear Information System (INIS)

DiCicco-Bloom, E.; Black, I.B.

1988-01-01

While neuronal mitosis is uniquely restricted to early development, the underlying regulation remains to be defined. The authors have now developed a dissociated, embryonic sympathetic neuron culture system that uses fully defined medium in which cells enter the mitotic cycle. The cultured cells expressed two neuronal traits, tyrosine hydroxylase and the neuron-specific 160-kDa neurofilament subunit protein, but were devoid of glial fibrillary acidic protein, a marker for non-myelin-forming Schwann cells in ganglia. Approximately one-third of the tyrosine hydroxylase-positive cells synthesized DNA in culture, specifically incorporating [ 3 H]thymidine into their nuclei. They used this system to define factors regulating the mitotic cycle in sympathetic neuroblasts. Members of the insulin family of growth factors, including insulin and insulin-like growth factors I and II, regulated DNA synthesis in the presumptive neuroblasts. Insulin more than doubled the proportion of tyrosine hydroxylase-positive cells entering the mitotic cycle, as indicated by autoradiography of [ 3 H]thymidine incorporation into nuclei. Scintillation spectrometry was an even more sensitive index of DNA synthesis. In contrast, the trophic protein nerve growth factor exhibited no mitogenic effect, suggesting that the mitogenic action of insulin growth factors is highly specific. The observations are discussed in the context of the detection of insulin growth factors and receptors in the developing brain

Mitotic effects of monochromatic ultraviolet radiation at 225, 265, and 280 nm on eleven stages of the cell cycle of the grasshopper neuroblast in culture. I. Overall retardation from the stage irradiated to nuclear membrane breakdown

International Nuclear Information System (INIS)

Carlson, J.G.

1976-01-01

Neuroblasts of Chortophaga viridifasciata (DeGeer) in culture were exposed to different doses of 225, 265, or 280 nm ultraviolet radiations at 11 different stages and substages of the mitotic cycle and individually selected cells were timed to breakdown of the nuclear membrane. Comparisons of the effectiveness of different wavelengths on the different stages were based on the dose that reduced the cell progression rate to 67 percent of normal (D 67 ) and the slope of the regression line, i.e., the control to treated time (C/T) ratio change/erg/mm 2 at the D 67 level. Cells of the prereplication period (metaphase + anaphase + early telophase) and the S phase (middle and late telophase + interphase + very early prophase) are equally sensitive to uv and contrast sharply with the much lower sensitivity of those in the postreplication period (early and middle prophase). This can best be interpreted if chromosomal DNA is the chromophore for uv-induced mitotic retardation. Cells in the prereplication period at exposure show no wavelength effect. In the S phase all stages except middle telophase and all stages combined are significantly more sensitive to 265 and 280 nm than to 225 nm. Of the postreplication stages, early prophase is retarded significantly more by 280 than by 225 or 265 nm. The C/T ratio/erg/mm 2 is greater after exposure to 265 nm at all prereplication and replication stages, but exhibits no consistent wavelength pattern during the postreplication period. Evidence based on the orientation of the neuroblast with respect to the uv-source suggests that the chromophore for mitotic retardation does not reside within the centrosome and related structures, but may be present, at least partly, in the nucleolus

Mitotic accumulation of dimethylated lysine 79 of histone H3 is important for maintaining genome integrity during mitosis in human cells.

Science.gov (United States)

Guppy, Brent J; McManus, Kirk J

2015-02-01

The loss of genome stability is an early event that drives the development and progression of virtually all tumor types. Recent studies have revealed that certain histone post-translational modifications exhibit dynamic and global increases in abundance that coincide with mitosis and exhibit essential roles in maintaining genomic stability. Histone H2B ubiquitination at lysine 120 (H2Bub1) is regulated by RNF20, an E3 ubiquitin ligase that is altered in many tumor types. Through an evolutionarily conserved trans-histone pathway, H2Bub1 is an essential prerequisite for subsequent downstream dimethylation events at lysines 4 (H3K4me2) and 79 (H3K79me2) of histone H3. Although the role that RNF20 plays in tumorigenesis has garnered much attention, the downstream components of the trans-histone pathway, H3K4me2 and H3K79me2, and their potential contributions to genome stability remain largely overlooked. In this study, we employ single-cell imaging and biochemical approaches to investigate the spatial and temporal patterning of RNF20, H2Bub1, H3K4me2, and H3K79me2 throughout the cell cycle, with a particular focus on mitosis. We show that H2Bub1, H3K4me2, and H3K79me2 exhibit distinct temporal progression patterns throughout the cell cycle. Most notably, we demonstrate that H3K79me2 is a highly dynamic histone post-translational modification that reaches maximal abundance during mitosis in an H2Bub1-independent manner. Using RNAi and chemical genetic approaches, we identify DOT1L as a histone methyltransferase required for the mitotic-associated increases in H3K79me2. We also demonstrate that the loss of mitotic H3K79me2 levels correlates with increases in chromosome numbers and increases in mitotic defects. Collectively, these data suggest that H3K79me2 dynamics during mitosis are normally required to maintain genome stability and further implicate the loss of H3K79me2 during mitosis as a pathogenic event that contributes to the development and progression of tumors

Axin localizes to mitotic spindles and centrosomes in mitotic cells

International Nuclear Information System (INIS)

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

2009-01-01

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 (GSK3β) 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 GSK3β 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

A retinoblastoma orthologue is a major regulator of S-phase, mitotic, and developmental gene expression in Dictyostelium.

Directory of Open Access Journals (Sweden)

Kimchi Strasser

Full Text Available The retinoblastoma tumour suppressor, Rb, has two major functions. First, it represses genes whose products are required for S-phase entry and progression thus stabilizing cells in G1. Second, Rb interacts with factors that induce cell-cycle exit and terminal differentiation. Dictyostelium lacks a G1 phase in its cell cycle but it has a retinoblastoma orthologue, rblA.Using microarray analysis and mRNA-Seq transcriptional profiling, we show that RblA strongly represses genes whose products are involved in S phase and mitosis. Both S-phase and mitotic genes are upregulated at a single point in late G2 and again in mid-development, near the time when cell cycling is reactivated. RblA also activates a set of genes unique to slime moulds that function in terminal differentiation.Like its mammalian counterpart Dictyostelium, RblA plays a dual role, regulating cell-cycle progression and transcriptional events leading to terminal differentiation. In the absence of a G1 phase, however, RblA functions in late G2 controlling the expression of both S-phase and mitotic genes.

THE INFLUENCE OF CAFFEINE ON MITOTIC DIVISION AT CAPSICUM ANNUUM L.

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Elena Rosu

2006-08-01

Full Text Available The paper presents, the caffeine effects in mitotic division at Capsicum annuum L.. The treatment has determined the lessening of the mitotic index (comparative with the control variant, until mitotic division total inhibition, as well as an growth frequency of division aberation in anaphase and telophase.

Robust mitotic entry is ensured by a latching switch

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Chloe Tuck

2013-07-01

Cell cycle events are driven by Cyclin dependent kinases (CDKs and by their counter-acting phosphatases. Activation of the Cdk1:Cyclin B complex during mitotic entry is controlled by the Wee1/Myt1 inhibitory kinases and by Cdc25 activatory phosphatase, which are themselves regulated by Cdk1:Cyclin B within two positive circuits. Impairing these two feedbacks with chemical inhibitors induces a transient entry into M phase referred to as mitotic collapse. The pathology of mitotic collapse reveals that the positive circuits play a significant role in maintaining the M phase state. To better understand the function of these feedback loops during G2/M transition, we propose a simple model for mitotic entry in mammalian cells including spatial control over Greatwall kinase phosphorylation. After parameter calibration, the model is able to recapture the complex and non-intuitive molecular dynamics reported by Potapova et al. (Potapova et al., 2011. Moreover, it predicts the temporal patterns of other mitotic regulators which have not yet been experimentally tested and suggests a general design principle of cell cycle control: latching switches buffer the cellular stresses which accompany cell cycle processes to ensure that the transitions are smooth and robust.

Robust mitotic entry is ensured by a latching switch.

Science.gov (United States)

Tuck, Chloe; Zhang, Tongli; Potapova, Tamara; Malumbres, Marcos; Novák, Béla

2013-01-01

Cell cycle events are driven by Cyclin dependent kinases (CDKs) and by their counter-acting phosphatases. Activation of the Cdk1:Cyclin B complex during mitotic entry is controlled by the Wee1/Myt1 inhibitory kinases and by Cdc25 activatory phosphatase, which are themselves regulated by Cdk1:Cyclin B within two positive circuits. Impairing these two feedbacks with chemical inhibitors induces a transient entry into M phase referred to as mitotic collapse. The pathology of mitotic collapse reveals that the positive circuits play a significant role in maintaining the M phase state. To better understand the function of these feedback loops during G2/M transition, we propose a simple model for mitotic entry in mammalian cells including spatial control over Greatwall kinase phosphorylation. After parameter calibration, the model is able to recapture the complex and non-intuitive molecular dynamics reported by Potapova et al. (Potapova et al., 2011). Moreover, it predicts the temporal patterns of other mitotic regulators which have not yet been experimentally tested and suggests a general design principle of cell cycle control: latching switches buffer the cellular stresses which accompany cell cycle processes to ensure that the transitions are smooth and robust.

The FEAR protein Slk19 restricts Cdc14 phosphatase to the nucleus until the end of anaphase, regulating its participation in mitotic exit in Saccharomyces cerevisiae.

Directory of Open Access Journals (Sweden)

Ann Marie E Faust

Full Text Available In Saccharomyces cerevisiae mitosis, the protein Slk19 plays an important role in the initial release of Cdc14 phosphatase from the nucleolus to the nucleus in early anaphase, an event that is critical for proper anaphase progression. A role for Slk19 in later mitotic stages of Cdc14 regulation, however, has not been demonstrated. While investigating the role of Slk19 post-translational modification on Cdc14 regulation, we found that a triple point mutant of SLK19, slk19(3R (three lysine-to-arginine mutations, strongly affects Cdc14 localization during late anaphase and mitotic exit. Using fluorescence live-cell microscopy, we found that, similar to slk19Δ cells, slk19(3R cells exhibit no defect in spindle stability and only a mild defect in spindle elongation dynamics. Unlike slk19Δcells, however, slk19(3R cells exhibit no defect in Cdc14 release from the nucleolus to the nucleus. Instead, slk19(3R cells are defective in the timing of Cdc14 movement from the nucleus to the cytoplasm at the end of anaphase. This mutant has a novel phenotype: slk19(3R causes premature Cdc14 movement to the cytoplasm prior to, rather than concomitant with, spindle disassembly. One consequence of this premature Cdc14 movement is the inappropriate activation of the mitotic exit network, made evident by the fact that slk19(3R partially rescues a mutant of the mitotic exit network kinase Cdc15. In conclusion, in addition to its role in regulating Cdc14 release from the nucleolus to the nucleus, we found that Slk19 is also important for regulating Cdc14 movement from the nucleus to the cytoplasm at the end of anaphase.

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

Science.gov (United States)

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

2016-09-02

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.

Physical Limits on the Precision of Mitotic Spindle Positioning by Microtubule Pushing forces: Mechanics of mitotic spindle positioning.

Science.gov (United States)

Howard, Jonathon; Garzon-Coral, Carlos

2017-11-01

Tissues are shaped and patterned by mechanical and chemical processes. A key mechanical process is the positioning of the mitotic spindle, which determines the size and location of the daughter cells within the tissue. Recent force and position-fluctuation measurements indicate that pushing forces, mediated by the polymerization of astral microtubules against- the cell cortex, maintain the mitotic spindle at the cell center in Caenorhabditis elegans embryos. The magnitude of the centering forces suggests that the physical limit on the accuracy and precision of this centering mechanism is determined by the number of pushing microtubules rather than by thermally driven fluctuations. In cells that divide asymmetrically, anti-centering, pulling forces generated by cortically located dyneins, in conjunction with microtubule depolymerization, oppose the pushing forces to drive spindle displacements away from the center. Thus, a balance of centering pushing forces and anti-centering pulling forces localize the mitotic spindles within dividing C. elegans cells. © 2017 The Authors. BioEssays published by Wiley Periodicals, Inc.

Phyllanthus emblica Fruit Extract Activates Spindle Assembly Checkpoint, Prevents Mitotic Aberrations and Genomic Instability in Human Colon Epithelial NCM460 Cells

Directory of Open Access Journals (Sweden)

Xihan Guo

2016-09-01

Full Text Available The fruit of Phyllanthus emblica Linn. (PE has been widely consumed as a functional food and folk medicine in Southeast Asia due to its remarkable nutritional and pharmacological effects. Previous research showed PE delays mitotic progress and increases genomic instability (GIN in human colorectal cancer cells. This study aimed to investigate the similar effects of PE by the biomarkers related to spindle assembly checkpoint (SAC, mitotic aberrations and GIN in human NCM460 normal colon epithelial cells. Cells were treated with PE and harvested differently according to the biomarkers observed. Frequencies of micronuclei (MN, nucleoplasmic bridge (NPB and nuclear bud (NB in cytokinesis-block micronucleus assay were used as indicators of GIN. Mitotic aberrations were assessed by the biomarkers of chromosome misalignment, multipolar division, chromosome lagging and chromatin bridge. SAC activity was determined by anaphase-to- metaphase ratio (AMR and the expression of core SAC gene budding uninhibited by benzimidazoles related 1 (BubR1. Compared with the control, PE-treated cells showed (1 decreased incidences of MN, NPB and NB (p < 0.01; (2 decreased frequencies of all mitotic aberration biomarkers (p < 0.01; and (3 decreased AMR (p < 0.01 and increased BubR1 expression (p < 0.001. The results revealed PE has the potential to protect human normal colon epithelial cells from mitotic and genomic damages partially by enhancing the function of SAC.

KCNK10, a Tandem Pore Domain Potassium Channel, Is a Regulator of Mitotic Clonal Expansion during the Early Stage of Adipocyte Differentiation

Directory of Open Access Journals (Sweden)

Makoto Nishizuka

2014-12-01

Full Text Available KCNK10, a member of tandem pore domain potassium channel family, gives rise to leak K+ currents. It plays important roles in stabilizing the negative resting membrane potential and in counterbalancing depolarization. We previously demonstrated that kcnk10 expression is quickly elevated during the early stage of adipogenesis of 3T3-L1 cells and that reduction of kcnk10 expression inhibits adipocyte differentiation. However, the molecular mechanism of KCNK10 in adipocyte differentiation remains unclear. Here we revealed that kcnk10 is induced by 3-isobutyl-1-methylxanthine, a cyclic nucleotide phosphodiesterase inhibitor and a potent inducer of adipogenesis, during the early stage of adipocyte differentiation. We also demonstrated that KCNK10 functions as a positive regulator of mitotic clonal expansion (MCE, a necessary process for terminal differentiation. The reduction of kcnk10 expression repressed the expression levels of CCAAT/enhancer-binding protein β (C/EBPβ and C/EBPδ as well as the phosphorylation level of Akt during the early phase of adipogenesis. In addition, knockdown of kcnk10 expression suppressed insulin-induced Akt phosphorylation. These results indicate that KCNK10 contributes to the regulation of MCE through the control of C/EBPβ and C/EBPδ expression and insulin signaling.

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

Directory of Open Access Journals (Sweden)

Cheen Fei Chin

2016-07-01

Full Text Available 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.

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

Science.gov (United States)

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

2016-02-02

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.

Increased spontaneous mitotic segregation in MMS-sensitive mutants of Saccharomyces cerevisiae

International Nuclear Information System (INIS)

Prakash, S.; Prakash, L.

1977-01-01

Methyl methanesulfonate (MMS)-sensitive mutants of Saccharomyces cerevisiae belonging to four different complementation groups, when homozygous, increase the rate of spontaneous mitotic segregation to canavanine resistance from heterozygous sensitive (can/sup r//+) diploids by 13- to 170-fold. The mms8-1 mutant is MMS and x-ray sensitive and increases the rate of spontaneous mitotic segregation 170-fold. The mms9-1 and mms13-1 mutants are sensitive to x rays and uv, respectively, in addition to MMS, and increase the rate of spontaneous mitotic segregation by 13-fold and 85-fold, respectively. The mutant mms21-1 is sensitive to MMS, x rays and uv and increases the rate of spontaneous mitotic segregation 23-fold

Revertant mosaicism in epidermolysis bullosa caused by mitotic gene conversion

NARCIS (Netherlands)

Jonkman, MF; Scheffer, H; Stulp, R; Pas, HH; Nijenhuis, Albertine; Heeres, K; Owaribe, K; Pulkkinen, L; Uitto, J

1997-01-01

Mitotic gene conversion acting as reverse mutation has not been previously demonstrated in human. We report here that the revertant mosaicism of a compound heterozygous proband with an autosomal recessive genodermatosis, generalized atrophic benign epidermolysis bullosa, is caused by mitotic gene

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Lifescience Database Archive (English)

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Full Text Available Oth.Emb.20.AllAg.Mitotic_cycle_14 dm3 TFs and others Embryo Mitotic cycle 14 SRX084...385 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Oth.Emb.20.AllAg.Mitotic_cycle_14.bed ...

File list: ALL.Emb.50.AllAg.Mitotic_cycle_14 [Chip-atlas[Archive

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File list: Pol.Emb.50.AllAg.Mitotic_cycle_12 [Chip-atlas[Archive

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File list: ALL.Emb.10.AllAg.Mitotic_cycle_14 [Chip-atlas[Archive

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File list: Oth.Emb.10.AllAg.Mitotic_cycle_13 [Chip-atlas[Archive

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File list: ALL.Emb.50.AllAg.Mitotic_cycle_12 [Chip-atlas[Archive

Lifescience Database Archive (English)

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File list: Pol.Emb.10.AllAg.Mitotic_cycle_14 [Chip-atlas[Archive

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File list: Pol.Emb.05.AllAg.Mitotic_cycle_13 [Chip-atlas[Archive

Lifescience Database Archive (English)

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Localization of latency-associated nuclear antigen (LANA) on mitotic chromosomes

Energy Technology Data Exchange (ETDEWEB)

Rahayu, Retno; Ohsaki, Eriko [Division of Virology, Department of Microbiology and Immunology, Osaka University Graduate School of Medicine, 2-2 Yamada-oka, Suita, Osaka 565-0871 (Japan); Omori, Hiroko [Central Instrumentation Laboratory Research Institute for Microbial Diseases (BIKEN), Osaka University, Osaka 565-0871 (Japan); Ueda, Keiji, E-mail: kueda@virus.med.osaka-u.ac.jp [Division of Virology, Department of Microbiology and Immunology, Osaka University Graduate School of Medicine, 2-2 Yamada-oka, Suita, Osaka 565-0871 (Japan)

2016-09-15

In latent infection of Kaposi's sarcoma-associated herpesvirus (KSHV), viral gene expression is extremely limited and copy numbers of viral genomes remain constant. Latency-associated nuclear antigen (LANA) is known to have a role in maintaining viral genome copy numbers in growing cells. Several studies have shown that LANA is localized in particular regions on mitotic chromosomes, such as centromeres/pericentromeres. We independently examined the distinct localization of LANA on mitotic chromosomes during mitosis, using super-resolution laser confocal microscopy and correlative fluorescence microscopy–electron microscopy (FM-EM) analyses. We found that the majority of LANA were not localized at particular regions such as telomeres/peritelomeres, centromeres/pericentromeres, and cohesion sites, but at the bodies of condensed chromosomes. Thus, LANA may undergo various interactions with the host factors on the condensed chromosomes in order to tether the viral genome to mitotic chromosomes and realize faithful viral genome segregation during cell division. - Highlights: • This is the first report showing LANA dots on mitotic chromosomes by fluorescent microscopy followed by electron microscopy. • LANA dots localized randomly on condensed chromosomes other than centromere/pericentromere and telomere/peritelomre. • Cellular mitotic checkpoint should not be always involved in the segregation of KSHV genomes in the latency.

Localization of latency-associated nuclear antigen (LANA) on mitotic chromosomes

International Nuclear Information System (INIS)

Rahayu, Retno; Ohsaki, Eriko; Omori, Hiroko; Ueda, Keiji

2016-01-01

In latent infection of Kaposi's sarcoma-associated herpesvirus (KSHV), viral gene expression is extremely limited and copy numbers of viral genomes remain constant. Latency-associated nuclear antigen (LANA) is known to have a role in maintaining viral genome copy numbers in growing cells. Several studies have shown that LANA is localized in particular regions on mitotic chromosomes, such as centromeres/pericentromeres. We independently examined the distinct localization of LANA on mitotic chromosomes during mitosis, using super-resolution laser confocal microscopy and correlative fluorescence microscopy–electron microscopy (FM-EM) analyses. We found that the majority of LANA were not localized at particular regions such as telomeres/peritelomeres, centromeres/pericentromeres, and cohesion sites, but at the bodies of condensed chromosomes. Thus, LANA may undergo various interactions with the host factors on the condensed chromosomes in order to tether the viral genome to mitotic chromosomes and realize faithful viral genome segregation during cell division. - Highlights: • This is the first report showing LANA dots on mitotic chromosomes by fluorescent microscopy followed by electron microscopy. • LANA dots localized randomly on condensed chromosomes other than centromere/pericentromere and telomere/peritelomre. • Cellular mitotic checkpoint should not be always involved in the segregation of KSHV genomes in the latency.

File list: His.Emb.05.AllAg.Mitotic_cycle_14 [Chip-atlas[Archive

Lifescience Database Archive (English)

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

Science.gov (United States)

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.

Interphase APC/C-Cdc20 inhibition by cyclin A2-Cdk2 ensures efficient mitotic entry

DEFF Research Database (Denmark)

Hein, Jamin B; Nilsson, Jakob

2016-01-01

Proper cell-cycle progression requires tight temporal control of the Anaphase Promoting Complex/Cyclosome (APC/C), a large ubiquitin ligase that is activated by one of two co-activators, Cdh1 or Cdc20. APC/C and Cdc20 are already present during interphase but APC/C-Cdc20 regulation during...... this window of the cell cycle, if any, is unknown. Here we show that cyclin A2-Cdk2 binds and phosphorylates Cdc20 in interphase and this inhibits APC/C-Cdc20 activity. Preventing Cdc20 phosphorylation results in pre-mature activation of the APC/C-Cdc20 and several substrates, including cyclin B1 and A2......, are destabilized which lengthens G2 and slows mitotic entry. Expressing non-degradable cyclin A2 but not cyclin B1 restores mitotic entry in these cells. We have thus uncovered a novel positive feedback loop centred on cyclin A2-Cdk2 inhibition of interphase APC/C-Cdc20 to allow further cyclin A2 accumulation...

A link between mitotic entry and membrane growth suggests a novel model for cell size control.

Science.gov (United States)

Anastasia, Steph D; Nguyen, Duy Linh; Thai, Vu; Meloy, Melissa; MacDonough, Tracy; Kellogg, Douglas R

2012-04-02

Addition of new membrane to the cell surface by membrane trafficking is necessary for cell growth. In this paper, we report that blocking membrane traffic causes a mitotic checkpoint arrest via Wee1-dependent inhibitory phosphorylation of Cdk1. Checkpoint signals are relayed by the Rho1 GTPase, protein kinase C (Pkc1), and a specific form of protein phosphatase 2A (PP2A(Cdc55)). Signaling via this pathway is dependent on membrane traffic and appears to increase gradually during polar bud growth. We hypothesize that delivery of vesicles to the site of bud growth generates a signal that is proportional to the extent of polarized membrane growth and that the strength of the signal is read by downstream components to determine when sufficient growth has occurred for initiation of mitosis. Growth-dependent signaling could explain how membrane growth is integrated with cell cycle progression. It could also control both cell size and morphogenesis, thereby reconciling divergent models for mitotic checkpoint function.

File list: ALL.Emb.10.AllAg.Mitotic_cycle_13 [Chip-atlas[Archive

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File list: ALL.Emb.05.AllAg.Mitotic_cycle_13 [Chip-atlas[Archive

Lifescience Database Archive (English)

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Mechanisms and Regulation of Mitotic Recombination in Saccharomyces cerevisiae

Science.gov (United States)

Symington, Lorraine S.; Rothstein, Rodney; Lisby, Michael

2014-01-01

Homology-dependent exchange of genetic information between DNA molecules has a profound impact on the maintenance of genome integrity by facilitating error-free DNA repair, replication, and chromosome segregation during cell division as well as programmed cell developmental events. This chapter will focus on homologous mitotic recombination in budding yeast Saccharomyces cerevisiae. However, there is an important link between mitotic and meiotic recombination (covered in the forthcoming chapter by Hunter et al. 2015) and many of the functions are evolutionarily conserved. Here we will discuss several models that have been proposed to explain the mechanism of mitotic recombination, the genes and proteins involved in various pathways, the genetic and physical assays used to discover and study these genes, and the roles of many of these proteins inside the cell. PMID:25381364

Centrosome Amplification Increases Single-Cell Branching in Post-mitotic Cells.

Science.gov (United States)

Ricolo, Delia; Deligiannaki, Myrto; Casanova, Jordi; Araújo, Sofia J

2016-10-24

Centrosome amplification is a hallmark of cancer, although we are still far from understanding how this process affects tumorigenesis [1, 2]. Besides the contribution of supernumerary centrosomes to mitotic defects, their biological effects in the post-mitotic cell are not well known. Here, we exploit the effects of centrosome amplification in post-mitotic cells during single-cell branching. We show that Drosophila tracheal cells with extra centrosomes branch more than wild-type cells. We found that mutations in Rca1 and CycA affect subcellular branching, causing tracheal tip cells to form more than one subcellular lumen. We show that Rca1 and CycA post-mitotic cells have supernumerary centrosomes and that other mutant conditions that increase centrosome number also show excess of subcellular lumen branching. Furthermore, we show that de novo lumen formation is impaired in mutant embryos with fewer centrioles. The data presented here define a requirement for the centrosome as a microtubule-organizing center (MTOC) for the initiation of subcellular lumen formation. We propose that centrosomes are necessary to drive subcellular lumen formation. In addition, centrosome amplification increases single-cell branching, a process parallel to capillary sprouting in blood vessels [3]. These results shed new light on how centrosomes can contribute to pathology independently of mitotic defects. Copyright © 2016 Elsevier Ltd. All rights reserved.

File list: His.Emb.50.AllAg.Mitotic_cycle_13-14 [Chip-atlas[Archive

Lifescience Database Archive (English)

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File list: His.Emb.20.AllAg.Mitotic_cycle_13-14 [Chip-atlas[Archive

Lifescience Database Archive (English)

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The Set1/COMPASS histone H3 methyltransferase helps regulate mitosis with the CDK1 and NIMA mitotic kinases in Aspergillus nidulans.

Science.gov (United States)

Govindaraghavan, Meera; Anglin, Sarah Lea; Osmani, Aysha H; Osmani, Stephen A

2014-08-01

Mitosis is promoted and regulated by reversible protein phosphorylation catalyzed by the essential NIMA and CDK1 kinases in the model filamentous fungus Aspergillus nidulans. Protein methylation mediated by the Set1/COMPASS methyltransferase complex has also been shown to regulate mitosis in budding yeast with the Aurora mitotic kinase. We uncover a genetic interaction between An-swd1, which encodes a subunit of the Set1 protein methyltransferase complex, with NIMA as partial inactivation of nimA is poorly tolerated in the absence of swd1. This genetic interaction is additionally seen without the Set1 methyltransferase catalytic subunit. Importantly partial inactivation of NIMT, a mitotic activator of the CDK1 kinase, also causes lethality in the absence of Set1 function, revealing a functional relationship between the Set1 complex and two pivotal mitotic kinases. The main target for Set1-mediated methylation is histone H3K4. Mutational analysis of histone H3 revealed that modifying the H3K4 target residue of Set1 methyltransferase activity phenocopied the lethality seen when either NIMA or CDK1 are partially functional. We probed the mechanistic basis of these genetic interactions and find that the Set1 complex performs functions with CDK1 for initiating mitosis and with NIMA during progression through mitosis. The studies uncover a joint requirement for the Set1 methyltransferase complex with the CDK1 and NIMA kinases for successful mitosis. The findings extend the roles of the Set1 complex to include the initiation of mitosis with CDK1 and mitotic progression with NIMA in addition to its previously identified interactions with Aurora and type 1 phosphatase in budding yeast. Copyright © 2014 by the Genetics Society of America.

Measuring mitotic spindle dynamics in budding yeast

Science.gov (United States)

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.

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Lifescience Database Archive (English)

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Lifescience Database Archive (English)

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Lifescience Database Archive (English)

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Lifescience Database Archive (English)

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Lifescience Database Archive (English)

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Lifescience Database Archive (English)

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Lifescience Database Archive (English)

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Lifescience Database Archive (English)

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Lifescience Database Archive (English)

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Lifescience Database Archive (English)

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Lifescience Database Archive (English)

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Lifescience Database Archive (English)

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Effect of bleomycin and irradiation on G2 progression

International Nuclear Information System (INIS)

Kimler, B.F.

1979-01-01

The interaction of bleomycin and x-irradiation on the induction of G 2 delay in Chinese hamster ovary cells was investigated utilizing the mitotic selection procedure for cell cycle analysis. Following the addition of BLM, the number of cells selected in mitosis remained at control level for a refractory period and then decreased. The location of the transition point, i.e., the age in G 2 at which cells become refractory to a progression blockade, was concentration-dependent, ranging from the S/G 2 boundary at low concentrations to the G 2 /M boundary at high concentrations. Depending upon the concentration of the drug used and the duration of exposure, the mitotic rate either decreased to zero or else leveled off at some intermediate value and then recovered to the control level. The duration of BLM-induced division delay was thus dependent upon the concentration used and the duration of exposure. When cells were treated with pulses of bleomycin (10-500 μg/ml) in addition to x-irradiation, the mitotic rate declined as with exposure to x-ray alone. However, the recovery from radiation-induced division delay and the subsequent reappearance of mitotic cells in the selection window was delayed until the cells had recovered from their BLM-induced division delay. This implies that, in contrast to the synergistic effects observed for cell lethality, BLM and radiation do not interact in the production of a progression blockade and the resultant division delay

Exposure of Human Lung Cancer Cells to 8-Chloro-Adenosine Induces G2/M Arrest and Mitotic Catastrophe

Directory of Open Access Journals (Sweden)

Hong-Yu Zhang

2004-11-01

Full Text Available 8-Chloro-adenosine (8-CI-Ado is a potent chemotherapeutic agent whose cytotoxicity in a variety of tumor cell lines has been widely investigated. However, the molecular mechanisms are uncertain. In this study, we found that exposure of human lung cancer cell lines A549 (p53-wt and H1299 (p53-depleted to 8-CI-Ado induced cell arrest in the G2/M phase, which was accompanied by accumulation of binucleated and polymorphonucleated cells resulting from aberrant mitosis and failed cytokinesis. Western blotting showed the loss of phosphorylated forms of Cdc2 and Cdc25C that allowed progression into mitosis. Furthermore, the increase in Ser10-phosphorylated histone H3-positive cells revealed by fluorescence-activated cell sorting suggested that the agent-targeted cells were able to exit the G2 phase and enter the M phase. Immunocytochemistry showed that microtubule and microfilament arrays were changed in exposed cells, indicating that the dynamic instability of microtubules and microfilaments was lost, which may correlate with mitotic dividing failure. Aberrant mitosis resulted in mitotic catastrophe followed by varying degrees of apoptosis, depending on the cell lines. Thus, 8-CI-Ado appears to exert its cytotoxicity toward cells in culture by inducing mitotic catastrophe.

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Lifescience Database Archive (English)

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Lifescience Database Archive (English)

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Unconventional functions of mitotic kinases in kidney tumourigenesis

Directory of Open Access Journals (Sweden)

Pauline eHascoet

2015-10-01

Full Text Available Human tumours 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 tumour types, including breast, colon and renal cell carcinoma. The Renal cell cancer (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 (Plk1, CK2, DLCK1 and Aurora kinases. In this review, we describe the non mitotic unconventional functions of these kinases in renal tumourigenesis.

Automatic Detection of Mitosis and Nuclei from Cytogenetic Images by CellProfiler Software for Mitotic Index Estimation

International Nuclear Information System (INIS)

Gonzalez, Jorge Ernesto; Romero, Ivonne; Garcia, Omar; Radl, Analia; Di Giorgio, Marina; Barquinero, Joan Francesc

2016-01-01

Mitotic Index (MI) estimation expressed as percentage of mitosis plays an important role as quality control endpoint. To this end, MI is applied to check the lot of media and reagents to be used throughout the assay and also to check cellular viability after blood sample shipping, indicating satisfactory/unsatisfactory conditions for the progression of cell culture. The objective of this paper was to apply the CellProfiler open-source software for automatic detection of mitotic and nuclei figures from digitized images of cultured human lymphocytes for MI assessment, and to compare its performance to that performed through semi-automatic and visual detection. Lymphocytes were irradiated and cultured for mitosis detection. Sets of images from cultures were analyzed visually and findings were compared with those using CellProfiler software. The CellProfiler pipeline includes the detection of nuclei and mitosis with 80% sensitivity and more than 99% specificity. We conclude that CellProfiler is a reliable tool for counting mitosis and nuclei from cytogenetic images, saves considerable time compared to manual operation and reduces the variability derived from the scoring criteria of different scorers. The CellProfiler automated pipeline achieves good agreement with visual counting workflow, i.e. it allows fully automated mitotic and nuclei scoring in cytogenetic images yielding reliable information with minimal user intervention. (authors)

Mechanism of APC/CCDC20 activation by mitotic phosphorylation.

Science.gov (United States)

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

2016-05-10

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/C(CDC20) 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/C(CDC20) 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/C(CDC20) 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.

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Lifescience Database Archive (English)

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Mitotic catastrophe is the mechanism of lethality for mutations that confer mutagen sensitivity in Aspergillus nidulans.

Science.gov (United States)

Denison, S H; May, G S

1994-01-16

We have examined the consequences of treatment with DNA-damaging agents of uvs mutants and the bimD6 mutant of Aspergillus nidulans. We first established that wild-type Aspergillus undergoes a cell cycle delay following treatment with the DNA-damaging agents methyl methanesulfonate (MMS) or ultraviolet light (UV). We have also determined that strains carrying the bimD6, uvsB110, uvsH77, uvsF201 and the uvsC114 mutations, all of which cause an increased sensitivity to DNA-damaging agents, undergo a cell-cycle delay following DNA damage. These mutations therefore do not represent nonfunctional checkpoints in Aspergillus. However, all of the mutant strains accumulated nuclear defects after a period of delay following mutagen treatment. The nuclear defects in the uvsB110 and bimD6 strains following MMS treatment were shown to be dependent on passage through mitosis after DNA damage, as the defects were prevented with benomyl. Checkpoint controls responding to DNA damage thus only temporarily halt cell-cycle progression in response to DNA damage. The conditional bimD6 mutation also results in a defective mitosis at restrictive temperatures. This mitotic defect is similar to that seen with MMS treatment at temperatures permissive for the mitotic defect. Thus the bimD gene product may perform dual roles, one in DNA repair and the other during the mitotic cell cycle in the absence of damage.

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Lifescience Database Archive (English)

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In-silico modeling of the mitotic spindle assembly checkpoint.

Directory of Open Access Journals (Sweden)

Bashar Ibrahim

2008-02-01

Full Text Available The Mitotic Spindle Assembly Checkpoint ((MSAC is an evolutionary conserved mechanism that ensures the correct segregation of chromosomes by restraining cell cycle progression from entering anaphase until all chromosomes have made proper bipolar attachments to the mitotic spindle. Its malfunction can lead to cancer.We have constructed and validated for the human (MSAC mechanism an in silico dynamical model, integrating 11 proteins and complexes. The model incorporates the perspectives of three central control pathways, namely Mad1/Mad2 induced Cdc20 sequestering based on the Template Model, MCC formation, and APC inhibition. Originating from the biochemical reactions for the underlying molecular processes, non-linear ordinary differential equations for the concentrations of 11 proteins and complexes of the (MSAC are derived. Most of the kinetic constants are taken from literature, the remaining four unknown parameters are derived by an evolutionary optimization procedure for an objective function describing the dynamics of the APC:Cdc20 complex. MCC:APC dissociation is described by two alternatives, namely the "Dissociation" and the "Convey" model variants. The attachment of the kinetochore to microtubuli is simulated by a switching parameter silencing those reactions which are stopped by the attachment. For both, the Dissociation and the Convey variants, we compare two different scenarios concerning the microtubule attachment dependent control of the dissociation reaction. Our model is validated by simulation of ten perturbation experiments.Only in the controlled case, our models show (MSAC behaviour at meta- to anaphase transition in agreement with experimental observations. Our simulations revealed that for (MSAC activation, Cdc20 is not fully sequestered; instead APC is inhibited by MCC binding.

Mitotic Figure Recognition: Agreement among Pathologists and Computerized Detector

Directory of Open Access Journals (Sweden)

Christopher Malon

2012-01-01

Full Text Available Despite the prognostic importance of mitotic count as one of the components of the Bloom – Richardson grade [3], several studies ([2, 9, 10] have found that pathologists’ agreement on the mitotic grade is fairly modest. Collecting a set of more than 4,200 candidate mitotic figures, we evaluate pathologists' agreement on individual figures, and train a computerized system for mitosis detection, comparing its performance to the classifications of three pathologists. The system’s and the pathologists’ classifications are based on evaluation of digital micrographs of hematoxylin and eosin stained breast tissue. On figures where the majority of pathologists agree on a classification, we compare the performance of the trained system to that of the individual pathologists. We find that the level of agreement of the pathologists ranges from slight to moderate, with strong biases, and that the system performs competitively in rating the ground truth set. This study is a step towards automatic mitosis count to accelerate a pathologist's work and improve reproducibility.

Disappearance of nucleosome positioning in mitotic chromatin in vivo.

Science.gov (United States)

Komura, Jun-ichiro; Ono, Tetsuya

2005-04-15

During mitosis, transcription is silenced and most transcription factors are displaced from their recognition sequences. By in vivo footprinting analysis, we have confirmed and extended previous studies showing loss of transcription factors from an RNA polymerase II promoter (c-FOS) and, for the first time, an RNA polymerase III promoter (U6) in HeLa cells. Because little was known about nucleosomal organization in mitotic chromosomes, we performed footprinting analysis for nucleosomes on these promoters in interphase and mitotic cells. During interphase, each of the promoters had a positioned nucleosome in the region intervening between proximal promoter elements and distal enhancer elements, but the strong nucleosome positioning disappeared during mitosis. Thus, the nucleosomal organization that appears to facilitate transcription in interphase cells may be lost in mitotic cells, and nucleosome positioning during mitosis does not seem to be a major component of the epigenetic mechanisms to mark genes for rapid reactivation after this phase.

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Lifescience Database Archive (English)

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Lifescience Database Archive (English)

Full Text Available InP.Emb.20.AllAg.Mitotic_cycle_11-13 dm3 Input control Embryo Mitotic cycle 11-13 S...RX645138 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/InP.Emb.20.AllAg.Mitotic_cycle_11-13.bed ...

Mitotic delay of irradiated cells and its connection with quantity of radiation injuries

International Nuclear Information System (INIS)

Lobachevskij, P.N.; Fominykh, E.V.

1989-01-01

The study is dedicated to development of mathematical approach to interpret radiation-induced mitosic delay. An assumption is made that mitotic delay is conditioned by discrete injuries distributed in cells according to stochasticity of interaction of radiation and target substance. It is supposed to consider the problem on injuries nature causing mitotic delay and to use the developed method for accounting the effect of radiation-induced mitotic delay on registered chromosomal aberration yield. 10 refs.; 2 figs.; 3 tabs

Suspension of Mitotic Activity in Dentate Gyrus of the Hibernating Ground Squirrel

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Victor I. Popov

2011-01-01

Full Text Available 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.

Mapping genes by meiotic and UV-induced mitotic recombination in Coprinus cinereus

International Nuclear Information System (INIS)

Amirkhanian, J.D.; Cowan, J.W.

1985-01-01

Three morphological mutants in Coprinus cinereus—one spontaneous (den-2) and two chemically induced (zigand sta)—were assigned to linkage groups and utilized in meiotic and mitotic mapping. Mutants den-2 and zig belong to linkage group III, den-2 being close to the centromere and about 20 map units (mu) from zig. The mutant sta in linkage group ‘G’ is at a distance of about 37 mu from ade-3. Mitotic mapping confirmed the gene order in linkage group III and provided evidence that trp-2 in linkage group ‘G’ was between the centromere and ade-3. These morphological mutants are compact in colony growth and therefore suited to high-density plating. The rarity of spontaneously occurring mitotic segregants suggests that diploids of Coprinus cinereus, heterozygous for morphoiogical markers in repuision, could serve as useful test systems for rapid screening of chemical mutagen/carcinogens via mitotic recombination studies

Automatic Detection of Mitosis and Nuclei From Cytogenetic Images by CellProfiler Software for Mitotic Index Estimation.

Science.gov (United States)

González, Jorge Ernesto; Radl, Analía; Romero, Ivonne; Barquinero, Joan Francesc; García, Omar; Di Giorgio, Marina

2016-12-01

Mitotic Index (MI) estimation expressed as percentage of mitosis plays an important role as quality control endpoint. To this end, MI is applied to check the lot of media and reagents to be used throughout the assay and also to check cellular viability after blood sample shipping, indicating satisfactory/unsatisfactory conditions for the progression of cell culture. The objective of this paper was to apply the CellProfiler open-source software for automatic detection of mitotic and nuclei figures from digitized images of cultured human lymphocytes for MI assessment, and to compare its performance to that performed through semi-automatic and visual detection. Lymphocytes were irradiated and cultured for mitosis detection. Sets of images from cultures were analyzed visually and findings were compared with those using CellProfiler software. The CellProfiler pipeline includes the detection of nuclei and mitosis with 80% sensitivity and more than 99% specificity. We conclude that CellProfiler is a reliable tool for counting mitosis and nuclei from cytogenetic images, saves considerable time compared to manual operation and reduces the variability derived from the scoring criteria of different scorers. The CellProfiler automated pipeline achieves good agreement with visual counting workflow, i.e. it allows fully automated mitotic and nuclei scoring in cytogenetic images yielding reliable information with minimal user intervention. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

The relationship between mitotic rate and depth of invasion in biopsies of malignant melanoma

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Ghasemi Basir HR

2018-03-01

Full Text Available Hamid Reza Ghasemi Basir,1,2 Pedram Alirezaei,2 Sara Ahovan,3 Abbas Moradi3 1Department of Pathology, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran; 2Psoriasis Research Center, Hamadan University of Medical Sciences, Hamadan, Iran; 3School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran Background: Malignant melanoma of the skin is a potentially lethal neoplasm that generally originates from atypical melanocytes in the dermal–epidermal junction. When the neoplasm penetrates into the dermis, several variables can affect the extent of its spread, among which depth of invasion has the most important prognostic value. Mitotic rate is another prognostic factor that reflects the biological behavior of the neoplasm.Objective: This study was designed to evaluate the probable relationship between the depth of invasion of malignant melanoma and its mitotic rate.Materials and methods: This study was performed on 50 excisional biopsy specimens that had received the diagnosis of malignant melanoma histopathologically. Tumor characteristics including Breslow thickness, Clark level, T-stage, and tumor mitotic rate were recorded.Results: We observed that at higher Clark levels and higher T-stages, and the mean mitotic rate was significantly increased. Moreover, there was a positive and significant correlation between Breslow thickness and mitotic rate. We demonstrated that one unit increase in mitotic rate was correlated with 0.8 mm increase in Breslow thickness of the tumor.Conclusion: In malignant melanoma, mitotic activity may probably indicate the depth of tumor invasion. Therefore, in incisional biopsies where depth of invasion cannot be accurately determined, the mitotic activity may be used to estimate Breslow thickness, which is necessary for planning surgical management. Keywords: melanoma, mitosis, Breslow, invasion, thickness, proliferation

Utilization during mitotic cell division of loci controlling meiotic recombination and disjunction in Drosophila melanogaster

International Nuclear Information System (INIS)

Baker, B.S.; Carpenter, A.T.C.; Ripoll, P.

1978-01-01

To inquire whether the loci identified by recombination-defective and disjunction-defective meiotic mutants in Drosophila are also utilized during mitotic cell division, the effects of 18 meiotic mutants (representing 13 loci) on mitotic chromosome stability have been examined genetically. To do this, meiotic-mutant-bearing flies heterozygous for recessive somatic cell markers were examined for the frequencies and types of spontaneous clones expressing the cell markers. In such flies, marked clones can arise via mitotic recombination, mutation, chromosome breakage, nondisjunction or chromosome loss, and clones from these different origins can be distinguished. In addition, meiotic mutants at nine loci have been examined for their effects on sensitivity to killing by uv and x rays. Mutants at six of the seven recombination-defective loci examined (mei-9, mei-41, c(3)G, mei-W68, mei-S282, mei-352, mei-218) cause mitotic chromosome instability in both sexes, whereas mutants at one locus (mei-218) do not affect mitotic chromosome stability. Thus many of the loci utilized during meiotic recombination also function in the chromosomal economy of mitotic cells

Mitotic chromosome condensation in vertebrates

International Nuclear Information System (INIS)

Vagnarelli, Paola

2012-01-01

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

Mitotic chromosome condensation in vertebrates

Energy Technology Data Exchange (ETDEWEB)

Vagnarelli, Paola, E-mail: P.Vagnarelli@ed.ac.uk

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

Induction of early differentiation as a means of cell sterilization

International Nuclear Information System (INIS)

Wangenheim, K.-H. v.

1979-01-01

Investigations in plants suggest that cytoplasmic growth during mitotic delay induces an early attainment of terminal differentiation and cessation of mitotic activity. In mammals a direct demonstration of these processes is difficult. Plants and mammals show, however, a common phenomenon: Polyploidy does not usually reduce radiosensitivity as drastically as predicted by genetical considerations and certain experimental results. In root meristems of barley it is shown that cytoplasmic growth during mitotic delay increases the amount of cytoplasma per nuclear genome to approximately the same levels in tetraploid as in diploid cells. This results in the same loss, for both ploidy levels, of meristematic cells due to early differentiation. Apparently, under usual conditions, polyploidy is unable to significantly reduce radiosensitivity because the induction of differentiation processes is more important to radiation damage than the direct effect of genetic damage. Since the same basic principles also occur in mammals, it is suggested that early differentiation, and thereby cell sterilization, are induced in mammalian cells by the same mechanism as in plants. (Auth.)

Radiation-induced mitotic and meiotic aneuploidy in the yeast Saccharomyces cerevisiae

International Nuclear Information System (INIS)

Parry, J.M.; Sharp, D.; Tippins, R.S.; Parry, E.M.

1979-01-01

A number of genetic systems are described which in yeast may be used to monitor the induction of chromosome aneuploidy during both mitotic and meiotic cell division. Using these systems the authors have been able to demonstrate the induction of both monosomic and trisomic cells in mitotically dividing cells and disomic spores in meiotically dividing cells after both UV light and X-ray exposure. (Auth.)

Neural stem cell-encoded temporal patterning delineates an early window of malignant susceptibility in Drosophila.

Science.gov (United States)

Narbonne-Reveau, Karine; Lanet, Elodie; Dillard, Caroline; Foppolo, Sophie; Chen, Ching-Huan; Parrinello, Hugues; Rialle, Stéphanie; Sokol, Nicholas S; Maurange, Cédric

2016-06-14

Pediatric neural tumors are often initiated during early development and can undergo very rapid transformation. However, the molecular basis of this early malignant susceptibility remains unknown. During Drosophila development, neural stem cells (NSCs) divide asymmetrically and generate intermediate progenitors that rapidly differentiate in neurons. Upon gene inactivation, these progeny can dedifferentiate and generate malignant tumors. Here, we find that intermediate progenitors are prone to malignancy only when born during an early window of development while expressing the transcription factor Chinmo, and the mRNA-binding proteins Imp/IGF2BP and Lin-28. These genes compose an oncogenic module that is coopted upon dedifferentiation of early-born intermediate progenitors to drive unlimited tumor growth. In late larvae, temporal transcription factor progression in NSCs silences the module, thereby limiting mitotic potential and terminating the window of malignant susceptibility. Thus, this study identifies the gene regulatory network that confers malignant potential to neural tumors with early developmental origins.

Identification of Pathways Required for the Coordination of Late Mitotic Events in Animal Cells

National Research Council Canada - National Science Library

Baumgartner, Bridget L; Harper, J. W

2005-01-01

... in genomic instability, a hallmark of cancer. In yeast, a signaling pathway has been identified, called the Mitotic Exit Network, which coordinates mitotic exit and cytokinesis with the end of anaphase...

Identification of Pathways Required for the Coordination of Late Mitotic Events in Animal Cells

National Research Council Canada - National Science Library

Baumgartner, Bridget

2004-01-01

... in genomic instability, a hallmark of cancer. In yeast, a signaling pathway has been identified, called the Mitotic Exit Network, which coordinates mitotic exit and cytokinesis with the end of anaphase...

Case of early pelviolumeral progressive muscular dystrophy associated with marked heart affection

International Nuclear Information System (INIS)

Gor'kova, N.B.; Starykh, L.M.; Karpova, L.E.

1991-01-01

A case of early pelviolumeral progressive muscular dystrophy detected in childhood and associated with marked heart affection is described. Patient underwent multimodality examination, including ECG, ultrasonography, roentgenography. It is shown that patients with progressive muscular dystrophy should receive medical supervision and treatment of both neuropathologist and therapist

Upregulation of meiosis-specific genes in lymphoma cell lines following genotoxic insult and induction of mitotic catastrophe

International Nuclear Information System (INIS)

Kalejs, Martins; Ivanov, Andrey; Plakhins, Gregory; Cragg, Mark S; Emzinsh, Dzintars; Illidge, Timothy M; Erenpreisa, Jekaterina

2006-01-01

We have previously reported that p53 mutated radioresistant lymphoma cell lines undergo mitotic catastrophe after irradiation, resulting in metaphase arrest and the generation of endopolyploid cells. A proportion of these endopolyploid cells then undergo a process of de-polyploidisation, stages of which are partially reminiscent of meiotic prophase. Furthermore, expression of meiosis-specific proteins of the cancer/testis antigens group of genes has previously been reported in tumours. We therefore investigated whether expression of meiosis-specific genes was associated with the polyploidy response in our tumour model. Three lymphoma cell lines, Namalwa, WI-L2-NS and TK6, of varying p53 status were exposed to a single 10 Gy dose of gamma radiation and their responses assessed over an extended time course. DNA flow cytometry and mitotic counts were used to assess the kinetics and extent of polyploidisation and mitotic progression. Expression of meiotic genes was analysed using RT-PCR and western blotting. In addition, localisation of the meiotic cohesin REC8 and its relation to centromeres was analysed by immunofluorescence. The principal meiotic regulator MOS was found to be significantly post-transcriptionally up-regulated after irradiation in p53 mutated but not p53 wild-type lymphoma cells. The maximum expression of MOS coincided with the maximal fraction of metaphase arrested cells and was directly proportional to both the extent of the arrest and the number of endopolyploid cells that subsequently emerged. The meiotic cohesin REC8 was also found to be up-regulated after irradiation, linking sister chromatid centromeres in the metaphase-arrested and subsequent giant cells. Finally, RT-PCR revealed expression of the meiosis-prophase genes, DMC1, STAG3, SYCP3 and SYCP1. We conclude that multiple meiotic genes are aberrantly activated during mitotic catastrophe in p53 mutated lymphoma cells after irradiation. Furthermore, we suggest that the coordinated expression

Aurora A's functions during mitotic exit: the Guess Who game

Directory of Open Access Journals (Sweden)

David eReboutier

2015-12-01

Full Text Available 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 of 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.

The MiAge Calculator: a DNA methylation-based mitotic age calculator of human tissue types.

Science.gov (United States)

Youn, Ahrim; Wang, Shuang

2018-01-01

Cell division is important in human aging and cancer. The estimation of the number of cell divisions (mitotic age) of a given tissue type in individuals is of great interest as it allows not only the study of biological aging (using a new molecular aging target) but also the stratification of prospective cancer risk. Here, we introduce the MiAge Calculator, a mitotic age calculator based on a novel statistical framework, the MiAge model. MiAge is designed to quantitatively estimate mitotic age (total number of lifetime cell divisions) of a tissue using the stochastic replication errors accumulated in the epigenetic inheritance process during cell divisions. With the MiAge model, the MiAge Calculator was built using the training data of DNA methylation measures of 4,020 tumor and adjacent normal tissue samples from eight TCGA cancer types and was tested using the testing data of DNA methylation measures of 2,221 tumor and adjacent normal tissue samples of five other TCGA cancer types. We showed that within each of the thirteen cancer types studied, the estimated mitotic age is universally accelerated in tumor tissues compared to adjacent normal tissues. Across the thirteen cancer types, we showed that worse cancer survivals are associated with more accelerated mitotic age in tumor tissues. Importantly, we demonstrated the utility of mitotic age by showing that the integration of mitotic age and clinical information leads to improved survival prediction in six out of the thirteen cancer types studied. The MiAge Calculator is available at http://www.columbia.edu/∼sw2206/softwares.htm .

Acquisition of Malay Word Recognition Skills: Lessons from Low-Progress Early Readers

Science.gov (United States)

Lee, Lay Wah; Wheldall, Kevin

2011-01-01

Malay is a consistent alphabetic orthography with complex syllable structures. The focus of this research was to investigate word recognition performance in order to inform reading interventions for low-progress early readers. Forty-six Grade 1 students were sampled and 11 were identified as low-progress readers. The results indicated that both…

Effect of caffeine on radiation-induced mitotic delay: delayed expression of G2 arrest

International Nuclear Information System (INIS)

Rowley, R.; Zorch, M.; Leeper, D.B.

1984-01-01

In the presence of 5 mM caffeine, irradiated (1.5 Gy) S and G 2 cells progressed to mitosis in register and without arrest in G 2 . Caffeine (5 mM) markedly reduced mitotic delay even after radiation doses up to 20 Gy. When caffeine was removed from irradiated (1.5 Gy) and caffeine-treated cells, a period of G 2 arrest followed, similar in length to that produced by radiation alone. The arrest expressed was independent of the duration of the caffeine treatment for exposures up to 3 hr. The similarity of the response to the cited effects of caffeine on S-phase delay suggests a common basis for delay induction in S and G 2 phases

Profiling DNA damage response following mitotic perturbations

DEFF Research Database (Denmark)

Pedersen, Ronni Sølvhøi; Karemore, Gopal; Gudjonsson, Thorkell

2016-01-01

that a broad spectrum of mitotic errors correlates with increased DNA breakage in daughter cells. Unexpectedly, we find that only a subset of these correlations are functionally linked. We identify the genuine mitosis-born DNA damage events and sub-classify them according to penetrance of the observed...

Effect of head-irradiation upon epidermal mitotic activity during wound healing in the adrenalectomized mice

International Nuclear Information System (INIS)

Kobayashi, Koshi

1977-01-01

Epidermal mitotic activity during wound healing was estimated both in the adrenalectomized, head-irradiated mice and in the adrenalectomized, non-irradiated mice, and was compared with those obtained previously from the unoperated, head-irradiated mice. It was found that head-irradiation caused a mitotic depression to a much smaller extent in the adrenalectomized mice than it did in the unoperated mice, though adrenalectomy itself had exerted a great inhibitory effect upon the mitosis induced by an injury. Whether this abscopal effect of head-irradiation upon the mitotic activity was mediated via the adrenals, and whether in the adrenalectomized mice the head-irradiation acted to increase epidermal response to injury, making the mitotic pattern of adrenalectomized mice to come near that of control mice were discussed. (auth.)

High frequency induction of mitotic recombination by ionizing radiation in Mlh1 null mouse cells

International Nuclear Information System (INIS)

Wang Qi; Ponomareva, Olga N.; Lasarev, Michael; Turker, Mitchell S.

2006-01-01

Mitotic recombination in somatic cells involves crossover events between homologous autosomal chromosomes. This process can convert a cell with a heterozygous deficiency to one with a homozygous deficiency if a mutant allele is present on one of the two homologous autosomes. Thus mitotic recombination often represents the second mutational step in tumor suppressor gene inactivation. In this study we examined the frequency and spectrum of ionizing radiation (IR)-induced autosomal mutations affecting Aprt expression in a mouse kidney cell line null for the Mlh1 mismatch repair (MMR) gene. The mutant frequency results demonstrated high frequency induction of mutations by IR exposure and the spectral analysis revealed that most of this response was due to the induction of mitotic recombinational events. High frequency induction of mitotic recombination was not observed in a DNA repair-proficient cell line or in a cell line with an MMR-independent mutator phenotype. These results demonstrate that IR exposure can initiate a process leading to mitotic recombinational events and that MMR function suppresses these events from occurring

Semaphorin-Plexin Signaling Controls Mitotic Spindle Orientation during Epithelial Morphogenesis and Repair

DEFF Research Database (Denmark)

Xia, Jingjing; Swiercz, Jakub M.; Bañón-Rodríguez, Inmaculada

2015-01-01

Morphogenesis, homeostasis, and regeneration of epithelial tissues rely on the accurate orientation of cell divisions, which is specified by the mitotic spindle axis. To remain in the epithelial plane, symmetrically dividing epithelial cells align their mitotic spindle axis with the plane. Here, we...... show that this alignment depends on epithelial cell-cell communication via semaphorin-plexin signaling. During kidney morphogenesis and repair, renal tubular epithelial cells lacking the transmembrane receptor Plexin-B2 or its semaphorin ligands fail to correctly orient the mitotic spindle, leading...... to severe defects in epithelial architecture and function. Analyses of a series of transgenic and knockout mice indicate that Plexin-B2 controls the cell division axis by signaling through its GTPase-activating protein (GAP) domain and Cdc42. Our data uncover semaphorin-plexin signaling as a central...

Effects of 5-fluorouracil on the mitotic activity of onion root tips apical meristem

Directory of Open Access Journals (Sweden)

Waldemar Lechowicz

2015-01-01

Full Text Available The effects of various concentrations of 5-FU on the mitotic activity of onion root tips apical meristem were investigated during 24-hour incubation in 5-FU and postincubation in water. The incubation in 5-FU caused a reversible inhibition of mitotic activity, and waves of the partially synchronised mitoses were observed during the period of postincubation. The most pronounced synchronisation of mitoses was obtained after incubation in 100 mg/l. 5-FU but the mitotic index of the resumed mitotic activity amounted to only one half of the control value. 5-FU was found to cause some cytological changes in meristematic cells such as enlargement of the nucleoli, change in the interphasic nuclei structure, appearance of subchromatid and chromatid aberrations and micronuclei. The effects of 5-FU on nucleic acids and the cell division cycle ace discussed and compared with the effects of 5-FUdR.

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

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Dina Dikovskaya

2015-09-01

Full Text Available 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.

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

Energy Technology Data Exchange (ETDEWEB)

Memin, Elisabeth, E-mail: molinac@mail.montclair.edu [Department of Biochemistry and Molecular Biology, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark, NJ 07103 (United States); Genzale, Megan [Department of Biochemistry and Molecular Biology, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark, NJ 07103 (United States); Crow, Marni; Molina, Carlos A. [Department of Biology and Molecular Biology, Montclair State University, Montclair, NJ, 07043 (United States)

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.

A Subpopulation of the K562 Cells Are Killed by Curcumin Treatment after G2/M Arrest and Mitotic Catastrophe.

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Macario Martinez-Castillo

Full Text Available Curcumin is extensively investigated as a good chemo-preventive agent in the development of many cancers and particularly in leukemia, including treatment of chronic myelogenous leukemia and it has been proposed as an adjuvant for leukemia therapies. Human chronic myeloid leukemia cells (K562, were treated with 20 μM of curcumin, and we found that a subpopulation of these cells were arrested and accumulate in the G2/M phase of the cell cycle. Characterization of this cell subpopulation showed that the arrested cells presented nuclear morphology changes resembling those described for mitotic catastrophe. Mitotic cells displayed abnormal chromatin organization, collapse of the mitotic spindle and abnormal chromosome segregation. Then, these cells died in an apoptosis dependent manner and showed diminution in the protein levels of BCL-2 and XIAP. Moreover, our results shown that a transient activation of the nuclear factor κB (NFκB occurred early in these cells, but decreased after 6 h of the treatment, explaining in part the diminution of the anti-apoptotic proteins. Additionally, P73 was translocated to the cell nuclei, because the expression of the C/EBPα, a cognate repressor of the P73 gene, was decreased, suggesting that apoptosis is trigger by elevation of P73 protein levels acting in concert with the diminution of the two anti-apoptotic molecules. In summary, curcumin treatment might produce a P73-dependent apoptotic cell death in chronic myelogenous leukemia cells (K562, which was triggered by mitotic catastrophe, due to sustained BAX and survivin expression and impairment of the anti-apoptotic proteins BCL-2 and XIAP.

Cell fate after mitotic arrest in different tumor cells is determined by the balance between slippage and apoptotic threshold

Energy Technology Data Exchange (ETDEWEB)

Galán-Malo, Patricia; Vela, Laura; Gonzalo, Oscar; Calvo-Sanjuán, Rubén; Gracia-Fleta, Lucía; Naval, Javier; Marzo, Isabel, E-mail: imarzo@unizar.es

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.

G1- and S-phase syntheses of histones H1 and H1o in mitotically selected CHO cells: utilization of high-performance liquid chromatography

International Nuclear Information System (INIS)

D'Anna, J.A.; Thayer, M.M.; Tobey, R.A.; Gurley, L.R.

1985-01-01

The authors have employed high-performance liquid chromatography (HPLC) to investigate the syntheses of histones H1 and H1o as synchronized cells traverse from mitosis to S phase. Chinese hamster (line CHO) cells were synchronized by mitotic selection, and, at appropriate times, they were pulse labeled for 1 h with [ 3 H]lysine. Histones H1 and H1o were extracted by blending radiolabeled and carrier cells directly in 0.83 M HC1O 4 ; the total HC1O 4 -soluble, Cl 3 CCO 2 H-precipitable proteins were then separated by a modification of an HPLC system employing three mu Bondapak reversed-phase columns. These procedures (1) produce minimally perturbed populations of synchronized proliferating cells and (2) maximize the recovery of radiolabeled histones during isolation and analysis. Measurements of rates of synthesis indicate that the rate of H1 synthesis increases as cells traverse from early to mid G1; as cells enter S phase, the rate of H1 synthesis increases an additional congruent to 22-fold and is proportional to the number of S-phase cells. In contrast to H1, the rate of H1o synthesis is nearly constant throughout G1. As cells progress into S phase, the rate of H1o synthesis increases so that it also appears to be proportional to the number of S-phase cells. Except for the first 1-2 h after mitotic selection, these results are similar to those obtained when cells are synchronized in G1 with the isoleucine deprivation procedure

Effect of colchicine on mitotic polyploidization and morphological ...

African Journals Online (AJOL)

Ajai

2012-05-15

May 15, 2012 ... to diseases and insects and reduction in fertility of flowering plants ..... soaking duration was noticed to cause the treated seeds to give low height .... Addison-. Wesley, London. Stadler J, Phillips RL, Leonard M (1989).Mitotic ...

The flavonoid eupatorin inactivates the mitotic checkpoint leading to polyploidy and apoptosis

Energy Technology Data Exchange (ETDEWEB)

Salmela, Anna-Leena [VTT Technical Research Centre of Finland, Medical Biotechnology, P.O. Box 106, Turku (Finland); Turku Graduate School of Biomedical Sciences, Turku (Finland); Turku Centre for Biotechnology, P.O. Box 123, University of Turku (Finland); Pouwels, Jeroen; Kukkonen-Macchi, Anu [VTT Technical Research Centre of Finland, Medical Biotechnology, P.O. Box 106, Turku (Finland); Waris, Sinikka; Toivonen, Pauliina [Turku Centre for Biotechnology, P.O. Box 123, University of Turku (Finland); Jaakkola, Kimmo [VTT Technical Research Centre of Finland, Medical Biotechnology, P.O. Box 106, Turku (Finland); Maeki-Jouppila, Jenni [VTT Technical Research Centre of Finland, Medical Biotechnology, P.O. Box 106, Turku (Finland); Turku Centre for Biotechnology, P.O. Box 123, University of Turku (Finland); Drug Discovery Graduate School, University of Turku (Finland); Kallio, Lila, E-mail: lila.kallio@vtt.fi [VTT Technical Research Centre of Finland, Medical Biotechnology, P.O. Box 106, Turku (Finland); Kallio, Marko J. [VTT Technical Research Centre of Finland, Medical Biotechnology, P.O. Box 106, Turku (Finland); Turku Centre for Biotechnology, P.O. Box 123, University of Turku (Finland); Centre of Excellence for Translational Genome-Scale Biology, P.O. Box 106, Academy of Finland (Finland)

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.

Cell radiosensitivity variation in synchronously-dividing root meristems of Pisum sativum L. and Zea mays L. during the mitotic cycle

International Nuclear Information System (INIS)

Gudkov, I.N.; Grodzinsky, D.M.

1982-01-01

The cell divisions in pea and maize seedling root meristems were synchronized by treatment with 0.03 per cent hydroxyurea for 24 hours. At different times after block cessation (removing seedlings from hydroxyurea), i.e. according to certain phases and subphases of the mitotic cycle, the seedlings were treated with 60 Co γ-radiation at doses from 3 to 32 Gy. Evaluation of seedling radioresistance by the survival of the main root meristem on the tenth day after irradiation led to the following sequence of cell stages in order of increasing resistance. For the pea root meristem: G 2 , M, late G 1 , early S, late S, middle S and early G 1 . For the maize root meristem: late G 2 , M, G 1 , early S, early G 2 , late S and middle S. (author)

Mitotically Active Leiomyoma of the Uterus in a Postmenopausal Breast Cancer Patient Receiving Tamoxifen

Directory of Open Access Journals (Sweden)

I-Feng Liu

2006-06-01

Conclusion: Endometrial cancer is rarely noted in breast cancer patients taking tamoxifen. Further, none have reported mitotically active leiomyoma of the uterus. From this case, endometrial proliferation and mitotically active leiomyoma of the uterus may be related to tamoxifen therapy, and should not be neglected in breast cancer patients.

Effect of tumor promoters on ultraviolet light-induced mutation and mitotic recombination in Saccharomyces cerevisiae

International Nuclear Information System (INIS)

Kunz, B.A.; Hannan, M.A.; Haynes, R.H.

1980-01-01

Recently, it has been suggested that mitotic recombination is involved in tumor promotion. On this basis, one might expect tumor promoters to be recombinagenic. D7 is a diploid strain of yeast in which both mutation and mitotic recombination can be measured. We have used this strain to assay the known tumor promoters, iodacetate, anthralin, and 12-0-tetradecanoylphorbol-13-acetate, and the cocarcinogen, catechol, for mutagenicity, recombinagenicity, and the ability to enhance ultraviolet light (UV)-induced genetic events. In the absence of preirradiation with UV, iodoacetate was found to be recombinagenic whereas catechol was mutagenic; however, in both cases, the effects were small. Iodoacetate, anthralin, and catechol potentiated UV-induced mitotic crossing-over, aberrant colony formation, and mutation, while catechol also increased UV-induced gene conversion. We were unable to detect any mutagenic or recombinagenic effect of 12-0-tetradecanoyl-phorbol-13-acetate in either whole cells or spheroplasts. Our results do not indicate any consistent correlation between tumor-promoting activity and the ability of an agent to induce mitotic recombination in yeast. However, the ability to potentiate UV-induced mutation and mitotic recombination may reflect the cocarcinogenic activity of certain promoters

The SUMO protease SENP1 is required for cohesion maintenance and mitotic arrest following spindle poison treatment

Energy Technology Data Exchange (ETDEWEB)

Era, Saho [Fondazione IFOM, Istituto FIRC di Oncologia Molecolare, IFOM-IEO campus, Via Adamello 16, 20139 Milan (Italy); Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida-Konoe, Sakyo-ku, Kyoto 606-8501 (Japan); Abe, Takuya; Arakawa, Hiroshi [Fondazione IFOM, Istituto FIRC di Oncologia Molecolare, IFOM-IEO campus, Via Adamello 16, 20139 Milan (Italy); Kobayashi, Shunsuke [Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida-Konoe, Sakyo-ku, Kyoto 606-8501 (Japan); Szakal, Barnabas [Fondazione IFOM, Istituto FIRC di Oncologia Molecolare, IFOM-IEO campus, Via Adamello 16, 20139 Milan (Italy); Yoshikawa, Yusuke; Motegi, Akira; Takeda, Shunichi [Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida-Konoe, Sakyo-ku, Kyoto 606-8501 (Japan); Branzei, Dana, E-mail: dana.branzei@ifom.eu [Fondazione IFOM, Istituto FIRC di Oncologia Molecolare, IFOM-IEO campus, Via Adamello 16, 20139 Milan (Italy)

2012-09-28

Highlights: Black-Right-Pointing-Pointer SENP1 knockout chicken DT40 cells are hypersensitive to spindle poisons. Black-Right-Pointing-Pointer Spindle poison treatment of SENP1{sup -/-} cells leads to increased mitotic slippage. Black-Right-Pointing-Pointer Mitotic slippage in SENP1{sup -/-} cells associates with apoptosis and endoreplication. Black-Right-Pointing-Pointer SENP1 counteracts sister chromatid separation during mitotic arrest. Black-Right-Pointing-Pointer Plk1-mediated cohesion down-regulation is involved in colcemid cytotoxicity. -- Abstract: SUMO conjugation is a reversible posttranslational modification that regulates protein function. SENP1 is one of the six SUMO-specific proteases present in vertebrate cells and its altered expression is observed in several carcinomas. To characterize SENP1 role in genome integrity, we generated Senp1 knockout chicken DT40 cells. SENP1{sup -/-} cells show normal proliferation, but are sensitive to spindle poisons. This hypersensitivity correlates with increased sister chromatid separation, mitotic slippage, and apoptosis. To test whether the cohesion defect had a causal relationship with the observed mitotic events, we restored the cohesive status of sister chromatids by introducing the TOP2{alpha}{sup +/-} mutation, which leads to increased catenation, or by inhibiting Plk1 and Aurora B kinases that promote cohesin release from chromosomes during prolonged mitotic arrest. Although TOP2{alpha} is SUMOylated during mitosis, the TOP2{alpha}{sup +/-} mutation had no obvious effect. By contrast, inhibition of Plk1 or Aurora B rescued the hypersensitivity of SENP1{sup -/-} cells to colcemid. In conclusion, we identify SENP1 as a novel factor required for mitotic arrest and cohesion maintenance during prolonged mitotic arrest induced by spindle poisons.

β-catenin at the centrosome: discrete pools of β-catenin communicate during mitosis and may co-ordinate centrosome functions and cell cycle progression.

Science.gov (United States)

Mbom, Bertrade C; Nelson, W James; Barth, Angela

2013-09-01

Beta-catenin is a multifunctional protein with critical roles in cell-cell adhesion, Wnt-signaling and the centrosome cycle. Whereas the roles of β-catenin in cell-cell adhesion and Wnt-signaling have been studied extensively, the mechanism(s) involving β-catenin in centrosome functions are poorly understood. β-Catenin localizes to centrosomes and promotes mitotic progression. NIMA-related protein kinase 2 (Nek2), which stimulates centrosome separation, binds to and phosphorylates β-catenin. β-Catenin interacting proteins involved in Wnt signaling such as adenomatous polyposis coli, Axin, and GSK3β, are also localized at centrosomes and play roles in promoting mitotic progression. Additionally, proteins associated with cell-cell adhesion sites, such as dynein, regulate mitotic spindle positioning. These roles of proteins at the cell cortex and Wnt signaling that involve β-catenin indicate a cross-talk between different sub-cellular sites in the cell at mitosis, and that different pools of β-catenin may co-ordinate centrosome functions and cell cycle progression. © 2013 WILEY Periodicals, Inc.

Progressive Decrease of Peripapillary Angioflow Vessel Density During Structural and Visual Field Progression in Early Primary Open-angle Glaucoma.

Science.gov (United States)

Holló, Gábor

2017-07-01

To present a case of early primary open-angle glaucoma in which retinal nerve fiber layer thickness (RNFLT), ganglion cell complex (GCC), and visual field progression were accompanied with significant progression of peripapillary angioflow vessel density (PAFD) measured with optical coherence tomographic angiography. A 68-year-old female patient who was under topical intraocular pressure (IOP) lowering medication for 20 years for ocular hypertension of the right and preperimetric primary open-angle glaucoma of the left eye (with reproducible inferotemporal and superotemporal neuroretinal rim and RNFL loss) was prospectively imaged with the AngioVue OCT for RNFLT, GCC thickness, and PAFD, and investigated with the Octopus Normal G2 visual field test on the same days at 6-month intervals for 18 months, while the IOP of the left eye escaped from control. IOP of the left eye fluctuated between 14 and 30 mm Hg in the study period. RNFLT, GCC thickness, and peripapillary PAFD all decreased significantly (linear regression analysis, P=0.030, 0.040, and 0.020, respectively), and a significant 2.1 dB/y progression was seen for a superior visual field cluster. The RNFLT, peripapillary PAFD, and visual field of the right eye remained normal and unchanged. In our case IOP elevation, glaucomatous visual field conversion, and structural progression were accompanied with significant progressive decrease of peripapillary PAFD. The simultaneous thinning of RNFLT and GCC and decrease of peripapillary PAFD suggest that PAFD may potentially be an additional indicator of early progression in primary open-angle glaucoma.

Genetic variation in mitotic regulatory pathway genes is associated with breast tumor grade

Science.gov (United States)

Purrington, Kristen S.; Slettedahl, Seth; Bolla, Manjeet K.; Michailidou, Kyriaki; Czene, Kamila; Nevanlinna, Heli; Bojesen, Stig E.; Andrulis, Irene L.; Cox, Angela; Hall, Per; Carpenter, Jane; Yannoukakos, Drakoulis; Haiman, Christopher A.; Fasching, Peter A.; Mannermaa, Arto; Winqvist, Robert; Brenner, Hermann; Lindblom, Annika; Chenevix-Trench, Georgia; Benitez, Javier; Swerdlow, Anthony; Kristensen, Vessela; Guénel, Pascal; Meindl, Alfons; Darabi, Hatef; Eriksson, Mikael; Fagerholm, Rainer; Aittomäki, Kristiina; Blomqvist, Carl; Nordestgaard, Børge G.; Nielsen, Sune F.; Flyger, Henrik; Wang, Xianshu; Olswold, Curtis; Olson, Janet E.; Mulligan, Anna Marie; Knight, Julia A.; Tchatchou, Sandrine; Reed, Malcolm W.R.; Cross, Simon S.; Liu, Jianjun; Li, Jingmei; Humphreys, Keith; Clarke, Christine; Scott, Rodney; Fostira, Florentia; Fountzilas, George; Konstantopoulou, Irene; Henderson, Brian E.; Schumacher, Fredrick; Le Marchand, Loic; Ekici, Arif B.; Hartmann, Arndt; Beckmann, Matthias W.; Hartikainen, Jaana M.; Kosma, Veli-Matti; Kataja, Vesa; Jukkola-Vuorinen, Arja; Pylkäs, Katri; Kauppila, Saila; Dieffenbach, Aida Karina; Stegmaier, Christa; Arndt, Volker; Margolin, Sara; Balleine, Rosemary; Arias Perez, Jose Ignacio; Pilar Zamora, M.; Menéndez, Primitiva; Ashworth, Alan; Jones, Michael; Orr, Nick; Arveux, Patrick; Kerbrat, Pierre; Truong, Thérèse; Bugert, Peter; Toland, Amanda E.; Ambrosone, Christine B.; Labrèche, France; Goldberg, Mark S.; Dumont, Martine; Ziogas, Argyrios; Lee, Eunjung; Dite, Gillian S.; Apicella, Carmel; Southey, Melissa C.; Long, Jirong; Shrubsole, Martha; Deming-Halverson, Sandra; Ficarazzi, Filomena; Barile, Monica; Peterlongo, Paolo; Durda, Katarzyna; Jaworska-Bieniek, Katarzyna; Tollenaar, Robert A.E.M.; Seynaeve, Caroline; Brüning, Thomas; Ko, Yon-Dschun; Van Deurzen, Carolien H.M.; Martens, John W.M.; Kriege, Mieke; Figueroa, Jonine D.; Chanock, Stephen J.; Lissowska, Jolanta; Tomlinson, Ian; Kerin, Michael J.; Miller, Nicola; Schneeweiss, Andreas; Tapper, William J.; Gerty, Susan M.; Durcan, Lorraine; Mclean, Catriona; Milne, Roger L.; Baglietto, Laura; dos Santos Silva, Isabel; Fletcher, Olivia; Johnson, Nichola; Van'T Veer, Laura J.; Cornelissen, Sten; Försti, Asta; Torres, Diana; Rüdiger, Thomas; Rudolph, Anja; Flesch-Janys, Dieter; Nickels, Stefan; Weltens, Caroline; Floris, Giuseppe; Moisse, Matthieu; Dennis, Joe; Wang, Qin; Dunning, Alison M.; Shah, Mitul; Brown, Judith; Simard, Jacques; Anton-Culver, Hoda; Neuhausen, Susan L.; Hopper, John L.; Bogdanova, Natalia; Dörk, Thilo; Zheng, Wei; Radice, Paolo; Jakubowska, Anna; Lubinski, Jan; Devillee, Peter; Brauch, Hiltrud; Hooning, Maartje; García-Closas, Montserrat; Sawyer, Elinor; Burwinkel, Barbara; Marmee, Frederick; Eccles, Diana M.; Giles, Graham G.; Peto, Julian; Schmidt, Marjanka; Broeks, Annegien; Hamann, Ute; Chang-Claude, Jenny; Lambrechts, Diether; Pharoah, Paul D.P.; Easton, Douglas; Pankratz, V. Shane; Slager, Susan; Vachon, Celine M.; Couch, Fergus J.

2014-01-01

Mitotic index is an important component of histologic grade and has an etiologic role in breast tumorigenesis. Several small candidate gene studies have reported associations between variation in mitotic genes and breast cancer risk. We measured associations between 2156 single nucleotide polymorphisms (SNPs) from 194 mitotic genes and breast cancer risk, overall and by histologic grade, in the Breast Cancer Association Consortium (BCAC) iCOGS study (n = 39 067 cases; n = 42 106 controls). SNPs in TACC2 [rs17550038: odds ratio (OR) = 1.24, 95% confidence interval (CI) 1.16–1.33, P = 4.2 × 10−10) and EIF3H (rs799890: OR = 1.07, 95% CI 1.04–1.11, P = 8.7 × 10−6) were significantly associated with risk of low-grade breast cancer. The TACC2 signal was retained (rs17550038: OR = 1.15, 95% CI 1.07–1.23, P = 7.9 × 10−5) after adjustment for breast cancer risk SNPs in the nearby FGFR2 gene, suggesting that TACC2 is a novel, independent genome-wide significant genetic risk locus for low-grade breast cancer. While no SNPs were individually associated with high-grade disease, a pathway-level gene set analysis showed that variation across the 194 mitotic genes was associated with high-grade breast cancer risk (P = 2.1 × 10−3). These observations will provide insight into the contribution of mitotic defects to histological grade and the etiology of breast cancer. PMID:24927736

The CRO-1 gene of Saccharomyces cerevisiae controls mitotic crossing over, chromosomal stability and sporulation

International Nuclear Information System (INIS)

Esposito, M.S.; Maleas, D.T.; Bjornstad, K.A.; Holbrook, L.L.

1987-01-01

The properties of a novel temperature-sensitive recombination-defective mutant of Saccharomyces cerevisiae, cro1-1 is described. The cro1-1 mutant is the first instance of a rec mutation that reduces drastically the rates of spontaneous mitotic crossing-over events but not those of gene conversional events. The cro1-1 mutation thus provides evidence that mitotic crossing-over is dependent upon gene products that are not essential for gene conversional events. The cro1-1 mutation also results in enhanced mitotic-chromosomal instability and MATa/MATα cro1-1/cro1-1 mutants are sporulation deficient. These phenotypes indicate that the CRO1 gene modulates mitotic chromosomal integrity and is essential for normal meiosis. The cro1-1 mutant possesses Holliday junction resolvase activity, hence its recombinational defect does not involve failure to execute this putative final recombinational step. 7 refs., 1 fig., 5 tabs

Loading of PAX3 to Mitotic Chromosomes Is Mediated by Arginine Methylation and Associated with Waardenburg Syndrome*

Science.gov (United States)

Wu, Tsu-Fang; Yao, Ya-Li; Lai, I-Lu; Lai, Chien-Chen; Lin, Pei-Lun; Yang, Wen-Ming

2015-01-01

PAX3 is a transcription factor critical to gene regulation in mammalian development. Mutations in PAX3 are associated with Waardenburg syndrome (WS), but the mechanism of how mutant PAX3 proteins cause WS remains unclear. Here, we found that PAX3 loads on mitotic chromosomes using its homeodomain. PAX3 WS mutants with mutations in homeodomain lose the ability to bind mitotic chromosomes. Moreover, loading of PAX3 on mitotic chromosomes requires arginine methylation, which is regulated by methyltransferase PRMT5 and demethylase JMJD6. Mutant PAX3 proteins that lose mitotic chromosome localization block cell proliferation and normal development of zebrafish. These results reveal the molecular mechanism of PAX3s loading on mitotic chromosomes and the importance of this localization pattern in normal development. Our findings suggest that PAX3 WS mutants interfere with the normal functions of PAX3 in a dominant negative manner, which is important to the understanding of the pathogenesis of Waardenburg syndrome. PMID:26149688

Deficiency of RITA results in multiple mitotic defects by affecting microtubule dynamics.

Science.gov (United States)

Steinhäuser, K; Klöble, P; Kreis, N-N; Ritter, A; Friemel, A; Roth, S; Reichel, J M; Michaelis, J; Rieger, M A; Louwen, F; Oswald, F; Yuan, J

2017-04-01

Deregulation of mitotic microtubule (MT) dynamics results in defective spindle assembly and chromosome missegregation, leading further to chromosome instability, a hallmark of tumor cells. RBP-J interacting and tubulin-associated protein (RITA) has been identified as a negative regulator of the Notch signaling pathway. Intriguingly, deregulated RITA is involved in primary hepatocellular carcinoma and other malignant entities. We were interested in the potential molecular mechanisms behind its involvement. We show here that RITA binds to tubulin and localizes to various mitotic MT structures. RITA coats MTs and affects their structures in vitro as well as in vivo. Tumor cell lines deficient of RITA display increased acetylated α-tubulin, enhanced MT stability and reduced MT dynamics, accompanied by multiple mitotic defects, including chromosome misalignment and segregation errors. Re-expression of wild-type RITA, but not RITA Δtub ineffectively binding to tubulin, restores the phenotypes, suggesting that the role of RITA in MT modulation is mediated via its interaction with tubulin. Mechanistically, RITA interacts with tubulin/histone deacetylase 6 (HDAC6) and its suppression decreases the binding of the deacetylase HDAC6 to tubulin/MTs. Furthermore, the mitotic defects and increased MT stability are also observed in RITA -/- mouse embryonic fibroblasts. RITA has thus a novel role in modulating MT dynamics and its deregulation results in erroneous chromosome segregation, one of the major reasons for chromosome instability in tumor cells.

Abnormal-induced theta activity supports early directed-attention network deficits in progressive MCI.

Science.gov (United States)

Deiber, Marie-Pierre; Ibañez, Vicente; Missonnier, Pascal; Herrmann, François; Fazio-Costa, Lara; Gold, Gabriel; Giannakopoulos, Panteleimon

2009-09-01

The electroencephalography (EEG) theta frequency band reacts to memory and selective attention paradigms. Global theta oscillatory activity includes a posterior phase-locked component related to stimulus processing and a frontal-induced component modulated by directed attention. To investigate the presence of early deficits in the directed attention-related network in elderly individuals with mild cognitive impairment (MCI), time-frequency analysis at baseline was used to assess global and induced theta oscillatory activity (4-6Hz) during n-back working memory tasks in 29 individuals with MCI and 24 elderly controls (EC). At 1-year follow-up, 13 MCI patients were still stable and 16 had progressed. Baseline task performance was similar in stable and progressive MCI cases. Induced theta activity at baseline was significantly reduced in progressive MCI as compared to EC and stable MCI in all n-back tasks, which were similar in terms of directed attention requirements. While performance is maintained, the decrease of induced theta activity suggests early deficits in the directed-attention network in progressive MCI, whereas this network is functionally preserved in stable MCI.

Nucleosynthesis in the early Galaxy: Progress and challenges.

Science.gov (United States)

Montes, Fernando

2015-10-01

Chemical imprints left by the first stars in the oldest stars of the Milky Way gives clues of the stellar nucleosynthesis responsible for the creation of elements heavier than iron. Recent progress in astronomical observations and in the modeling of the chemical evolution of the Galaxy have shown that multiple nucleosynthesis processes may operate at those early times. In this talk I will review some of that evidence along with the important role that nuclear reactions play in those processes. I will focus in progress in our understanding of the rapid neutron capture process (r-process) and in new results on nucleosynthesis in core-collapse supernovae and neutrino-driven winds that produce elements up to silver. I will show some examples of recent nuclear physics measurements addressing the need for better nuclear data and give an outlook of the remaining challenges and future plans to continue those measurements.

Cell radiosensitivity variation in synchronously-dividing root meristems of Pisum sativum L. and Zea mays L. during the mitotic cycle

Energy Technology Data Exchange (ETDEWEB)

Gudkov, I.N.; Grodzinsky, D.M. (AN Ukrainskoj SSR, Kiev. Inst. Fiziologii Rastenij)

1982-04-01

The cell divisions in pea and maize seedling root meristems were synchronized by treatment with 0.03 per cent hydroxyurea for 24 hours. At different times after block cessation (removing seedlings from hydroxyurea), i.e. according to certain phases and subphases of the mitotic cycle, the seedlings were treated with /sup 60/Co ..gamma..-radiation at doses from 3 to 32 Gy. Evaluation of seedling radioresistance by the survival of the main root meristem on the tenth day after irradiation led to the following sequence of cell stages in order of increasing resistance. For the pea root meristem: G/sub 2/, M, late G/sub 1/, early S, late S, middle S and early G/sub 1/. For the maize root meristem: late G/sub 2/, M, G/sub 1/, early S, early G/sub 2/, late S and middle S.

Taxane-mediated radiosensitization derives from chromosomal missegregation on tripolar mitotic spindles orchestrated by AURKA and TPX2.

Science.gov (United States)

Orth, M; Unger, K; Schoetz, U; Belka, C; Lauber, K

2018-01-04

Taxane-based radiochemotherapy is a central treatment option for various cancer entities in locally advanced stages. The therapeutic synergism of this combined modality approach due to taxane-mediated radiosensitization of cancer cells is well-known. However, the underlying molecular mechanisms remain largely elusive, and mechanism-derived predictive markers of taxane-based radiochemotherapy are currently not available. Here, we show that clinically relevant doses of Paclitaxel, the prototype taxane, stimulate a tripolar mode of mitosis leading to chromosomal missegregation and aneuploidization rather than interfering with cell cycle progression. This distinct mitotic phenotype was interlinked with Paclitaxel-mediated radiosensitization via overexpression of mitotic Aurora kinase A (AURKA) and its cofactor TPX2 whose knockdown rescued the bipolar mode of cell division and largely attenuated the radiosensitizing effects of Paclitaxel. In the cancer genome atlas (TCGA) lung adenocarcinoma cohort, high expression levels of AURKA and TPX2 were associated with specifically improved overall survival upon taxane-based radiochemotherapy, but not in case of non-taxane-based radiochemotherapy, chemo- or radiotherapy only. Thus, our data provide insights into Paclitaxel-mediated radiosensitization on a mechanistic and molecular level and identify AURKA and TPX2 as the first potential mechanism-based, predictive markers of taxane-based radiochemotherapy.

Mitotic Stress in Cancer: Tipping the Fine Balance

Indian Academy of Sciences (India)

Acer

of these molecules do not fit into the classical definition of oncogenes or tumor suppressor genes. In some cases, both over-expression and decreased expression of these genes result in mitotic arrest. Moreover, some .... The Clinical Collaborators: Dr. Arunabha Sengupta. Dr. Arun Roy. Dr. Jayanta Chakrabarty, CNCI. Prof.

Mitotic recombination induced by chemical and physical agents in the yeast Saccharomyces cerevisiae

International Nuclear Information System (INIS)

Davies, P.J.; Evans, W.E.; Parry, J.M.

1975-01-01

The treatment of diploid cultures of yeast with ultraviolet light (uv), γ-rays, nitrous acid (na) and ethyl methane sulphonate (ems) results in increases in cell death, mitotic gene conversion and crossing-over. Acridine orange (ao) treatment, in contrast, was effective only in increasing the frequency of gene conversion. The individual mutagens were effective in the order uv>na>γ-rays>ao>ems. Prior treatment of yeast cultures in starvation medium produced a significant reduction in the yield of induced gene conversion. The results have been interpreted on the basis of a general model of mitotic gene conversion which involves the post-replication repair of induced lesions involving de novo DNA synthesis without genetic exchange. In contrast mitotic crossing-over appears to involve the action of a repair system independent from excision or post-replication repair which involves genetic exchange between homologous chromosomes

Early intranasal insulin therapy halts progression of neurodegeneration: progress in Alzheimer's disease therapeutics.

Science.gov (United States)

de la Monte, Suzanne M

Evaluation of Craft S, Baker LD, Montine TJ, Minoshima S, Watson GS, Claxton A, et al. Intranasal Insulin Therapy for Alzheimer Disease and Amnestic Mild Cognitive Impairment: A Pilot Clinical Trial. Arch Neurol . 2011 Sep 12. Alzheimer's disease is associated with brain insulin deficiency and insulin resistance, similar to the problems in diabetes. If insulin could be supplied to the brain in the early stages of Alzheimer's, subsequent neurodegeneration might be prevented. Administering systemic insulin to elderly non-diabetics poses unacceptable risks of inadvertant hypoglycemia. However, intranasal delivery directs the insulin into the brain, avoiding systemic side-effects. This pilot study demonstrates both efficacy and safety of using intranasal insulin to treat early Alzheimer's and mild cognitive impairment, i.e. the precursor to Alzheimer's. Significant improvements in learning, memory, and cognition occured within a few months, but without intranasal insulin, brain function continued to deteriorate in measurable degrees. Intranasal insulin therapy holds promise for halting progression of Alzheimer's disease.

Progressively Disrupted Intrinsic Functional Connectivity of Basolateral Amygdala in Very Early Alzheimer’s Disease

Directory of Open Access Journals (Sweden)

Marion Ortner

2016-09-01

Full Text Available Abstract:Very early Alzheimer’s disease (AD - i.e., AD at stages of mild cognitive impairment (MCI and mild dementia - is characterized by progressive structural and neuropathologic changes such as atrophy or tangle deposition in medial temporal lobes, including hippocampus and entorhinal cortex but also adjacent amygdala. While progressively disrupted intrinsic connectivity of hippocampus with other brain areas has been demonstrated by many studies, amygdala connectivity was rarely investigated in AD, notwithstanding its known relevance for emotion processing and mood disturbances, which are both important in early AD. Intrinsic functional connectivity (iFC patterns of hippocampus and amygdala overlap in healthy persons. Thus, we hypothesized that increased alteration of iFC patterns along AD is not limited to the hippocampus but also concerns the amygdala, independent from atrophy. To address this hypothesis, we applied structural and functional resting-state MRI in healthy controls (CON, n=33 and patients with AD in the stages of MCI (AD-MCI, n=38 and mild dementia (AD-D, n=36. Outcome measures were voxel-based morphometry (VBM values and region of interest-based intrinsic functional connectivity maps (iFC of basolateral amygdala, which has extended cortical connectivity. Amygdala VBM values were progressively reduced in patients (CON > AD-MCI and AD-D. Amygdala iFC was progressively reduced along impairment severity (CON > AD-MCI > AD-D, particularly for hippocampus, temporal lobes, and fronto-parietal areas. Notably, decreased iFC was independent of amygdala atrophy. Results demonstrate progressively impaired amygdala intrinsic connectivity in temporal and fronto-parietal lobes independent from increasing amygdala atrophy in very early AD. Data suggest that early AD disrupts intrinsic connectivity of medial temporal lobe key regions including that of amygdala.

Loss of p120 catenin and links to mitotic alterations, inflammation, and skin cancer

DEFF Research Database (Denmark)

Perez-Moreno, Mirna; Song, Weimin; Pasolli, H Amalia

2008-01-01

Tumor formation involves epigenetic modifications and microenvironmental changes as well as cumulative genetic alterations encompassing somatic mutations, loss of heterozygosity, and aneuploidy. Here, we show that conditional targeting of p120 catenin in mice leads to progressive development...... of skin neoplasias associated with intrinsic NF-kappaB activation. We find that, similarly, squamous cell carcinomas in humans display altered p120 and activated NF-kappaB. We show that epidermal hyperproliferation arising from p120 loss can be abrogated by IkappaB kinase 2 inhibitors. Although...... this underscores the importance of this pathway, the role of NF-kappaB in hyperproliferation appears rooted in its impact on epidermal microenvironment because as p120-null keratinocytes display a growth-arrested phenotype in culture. We trace this to a mitotic defect, resulting in unstable, binucleated cells...

The Effect Of PHA And SEA On Mitotic Index Of Lymphocyte Cell Of Macaca Fasciulare

International Nuclear Information System (INIS)

Lubis, Masnelli; Iwiq-Indrawati

2003-01-01

The observation of influences of PHA (phytohemagglutinin) and SEA (staphilucoccal enterotoxin A) on mitotic index of lymphocyte of Macaca Fascicularis had been done. Half milliliters of lymphocyte cells stimulated with PHA or SEA were cultured in 10 ml RPMI + 1.0 ml Fetal Bouvine Serum (FBS ) + 0.1 ml L-glutamine + 0.15 ml PHA or 0.1 ml SEA ( 0.5 μg/ml ) + 0.1 ml Colchisin on 37 degree C for 96 hours. The result demonstrated that the frequency of mitotic index stimulated with PHA was higher than that of SEA. The average of mitotic index with PHA was 18.56 %, and with SEA was 8.3 %. (author)

Loading of PAX3 to Mitotic Chromosomes Is Mediated by Arginine Methylation and Associated with Waardenburg Syndrome.

Science.gov (United States)

Wu, Tsu-Fang; Yao, Ya-Li; Lai, I-Lu; Lai, Chien-Chen; Lin, Pei-Lun; Yang, Wen-Ming

2015-08-14

PAX3 is a transcription factor critical to gene regulation in mammalian development. Mutations in PAX3 are associated with Waardenburg syndrome (WS), but the mechanism of how mutant PAX3 proteins cause WS remains unclear. Here, we found that PAX3 loads on mitotic chromosomes using its homeodomain. PAX3 WS mutants with mutations in homeodomain lose the ability to bind mitotic chromosomes. Moreover, loading of PAX3 on mitotic chromosomes requires arginine methylation, which is regulated by methyltransferase PRMT5 and demethylase JMJD6. Mutant PAX3 proteins that lose mitotic chromosome localization block cell proliferation and normal development of zebrafish. These results reveal the molecular mechanism of PAX3s loading on mitotic chromosomes and the importance of this localization pattern in normal development. Our findings suggest that PAX3 WS mutants interfere with the normal functions of PAX3 in a dominant negative manner, which is important to the understanding of the pathogenesis of Waardenburg syndrome. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Effects of mutagen-sensitive mus mutations on spontaneous mitotic recombination in Aspergillus.

Science.gov (United States)

Zhao, P; Kafer, E

1992-04-01

Methyl methane-sulfonate (MMS)-sensitive, radiation-induced mutants of Aspergillus were shown to define nine new DNA repair genes, musK to musS. To test mus mutations for effects on mitotic recombination, intergenic crossing over was assayed between color markers and their centromeres, and intragenic recombination between two distinguishable adE alleles. Of eight mutants analyzed, four showed significant deviations from mus+ controls in both tests. Two mutations, musK and musL, reduced recombination, while musN and musQ caused increases. In contrast, musO diploids produced significantly higher levels only for intragenic recombination. Effects were relatively small, but averages between hypo- and hyperrec mus differed 15-20-fold. In musL diploids, most of the rare color segregants resulted from mitotic malsegregation rather than intergenic crossing over. This indicates that the musL gene product is required for recombination and that DNA lesions lead to chromosome loss when it is deficient. In addition, analysis of the genotypes of intragenic (ad+) recombinants showed that the musL mutation specifically reduced single allele conversion but increased complex conversion types (especially recombinants homozygous for ad+). Similar analysis revealed differences between the effects of two hyperrec mutations; musN apparently caused high levels solely of mitotic crossing over, while musQ increased various conversion types but not reciprocal crossovers. These results suggest that mitotic gene conversion and crossing over, while generally associated, are affected differentially in some of the mus strains of Aspergillus nidulans.

Rho proteins − the key regulators of cytoskeleton in the progression of mitosis and cytokinesis

Directory of Open Access Journals (Sweden)

Anna Klimaszewska

2011-11-01

Full Text Available The Rho proteins are members of the Ras superfamily of small GTPases. They are thought to be crucial regulators of multiple signal transduction pathways that influence a wide range of cellular functions, including migration, membrane trafficking, adhesion, polarity and cell shape changes. Thanks to their ability to control the assembly and organization of the actin and microtubule cytoskeletons, Rho GTPases are known to regulate mitosis and cytokinesis progression. These proteins are required for formation and rigidity of the cortex during mitotic cell rounding, mitotic spindle formation and attachment of the spindle microtubules to the kinetochore. In addition, during cytokinesis, they are involved in promoting division plane determination, contractile ring and cleavage furrow formation and abscission. They are also known as regulators of cell cycle progression at the G1/S and G2/M transition. Thus, the signal transduction pathways in which Rho proteins participate, appear to connect dynamics of actin and microtubule cytoskeletons to cell cycle progression. We review the current state of knowledge concerning the molecular mechanisms by which Rho GTPase signaling regulates remodeling of actin and microtubule cytoskeletons in order to control cell division progression.

CYTOGENETICS EFFECTS INDUCED BY NITRATE OF LEAD ON MITOTIC DIVISION AT ALLIUM CEPA L.

OpenAIRE

Silvica Padureanu

2005-01-01

The paper presents the influence of nitrate of lead upon the mitotic division of Allium cepa L. The treatment with nitrate of lead has determined the lessening of the mitotic index and the chromosomial mutations. Also nitrate of lead determined in little proportion cells autopoliploid. The experiment prowed that nitrate of lead, known as a polluting agent has a mutagenic potential on the plants.

Wnt activation followed by Notch inhibition promotes mitotic hair cell regeneration in the postnatal mouse cochlea

Science.gov (United States)

Li, Wenyan; Chen, Yan; Zhang, Shasha; Tang, Mingliang; Sun, Shan; Chai, Renjie; Li, Huawei

2016-01-01

Hair cell (HC) loss is the main cause of permanent hearing loss in mammals. Previous studies have reported that in neonatal mice cochleae, Wnt activation promotes supporting cell (SC) proliferation and Notch inhibition promotes the trans-differentiation of SCs into HCs. However, Wnt activation alone fails to regenerate significant amounts of new HCs, Notch inhibition alone regenerates the HCs at the cost of exhausting the SC population, which leads to the death of the newly regenerated HCs. Mitotic HC regeneration might preserve the SC number while regenerating the HCs, which could be a better approach for long-term HC regeneration. We present a two-step gene manipulation, Wnt activation followed by Notch inhibition, to accomplish mitotic regeneration of HCs while partially preserving the SC number. We show that Wnt activation followed by Notch inhibition strongly promotes the mitotic regeneration of new HCs in both normal and neomycin-damaged cochleae while partially preserving the SC number. Lineage tracing shows that the majority of the mitotically regenerated HCs are derived specifically from the Lgr5+ progenitors with or without HC damage. Our findings suggest that the co-regulation of Wnt and Notch signaling might provide a better approach to mitotically regenerate HCs from Lgr5+ progenitor cells. PMID:27564256

Frequencies of mutagen-induced coincident mitotic recombination at unlinked loci in Saccharomyces cerevisiae

Energy Technology Data Exchange (ETDEWEB)

Freeman, Kathryn M. [Department of Biology, College of the Holy Cross, One College Street, Worcester, MA 01610-2395 (United States); Hoffmann, George R. [Department of Biology, College of the Holy Cross, One College Street, Worcester, MA 01610-2395 (United States)]. E-mail: ghoffmann@holycross.edu

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{sup +} 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.

Cell cycle-dependent SUMO-1 conjugation to nuclear mitotic apparatus protein (NuMA)

Energy Technology Data Exchange (ETDEWEB)

Seo, Jae Sung; Kim, Ha Na; Kim, Sun-Jick; Bang, Jiyoung; Kim, Eun-A; Sung, Ki Sa [Department of Biological Sciences, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Yoon, Hyun-Joo [TissueGene Inc. 9605 Medical Center Dr., Rockville, MD 20850 (United States); Yoo, Hae Yong [Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Samsung Medical Center, Sungkyunkwan University, Seoul 135-710 (Korea, Republic of); Choi, Cheol Yong, E-mail: choicy@skku.ac.kr [Department of Biological Sciences, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

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.

Frequencies of mutagen-induced coincident mitotic recombination at unlinked loci in Saccharomyces cerevisiae

International Nuclear Information System (INIS)

Freeman, Kathryn M.; Hoffmann, George R.

2007-01-01

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, β-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

Dietary flavonoid fisetin induces a forced exit from mitosis by targeting the mitotic spindle checkpoint

Science.gov (United States)

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

A deep learning based strategy for identifying and associating mitotic activity with gene expression derived risk categories in estrogen receptor positive breast cancers.

Science.gov (United States)

Romo-Bucheli, David; Janowczyk, Andrew; Gilmore, Hannah; Romero, Eduardo; Madabhushi, Anant

2017-06-01

The treatment and management of early stage estrogen receptor positive (ER+) breast cancer is hindered by the difficulty in identifying patients who require adjuvant chemotherapy in contrast to those that will respond to hormonal therapy. To distinguish between the more and less aggressive breast tumors, which is a fundamental criterion for the selection of an appropriate treatment plan, Oncotype DX (ODX) and other gene expression tests are typically employed. While informative, these gene expression tests are expensive, tissue destructive, and require specialized facilities. Bloom-Richardson (BR) grade, the common scheme employed in breast cancer grading, has been shown to be correlated with the Oncotype DX risk score. Unfortunately, studies have also shown that the BR grade determined experiences notable inter-observer variability. One of the constituent categories in BR grading is the mitotic index. The goal of this study was to develop a deep learning (DL) classifier to identify mitotic figures from whole slides images of ER+ breast cancer, the hypothesis being that the number of mitoses identified by the DL classifier would correlate with the corresponding Oncotype DX risk categories. The mitosis detector yielded an average F-score of 0.556 in the AMIDA mitosis dataset using a 6-fold validation setup. For a cohort of 174 whole slide images with early stage ER+ breast cancer for which the corresponding Oncotype DX score was available, the distributions of the number of mitoses identified by the DL classifier was found to be significantly different between the high vs low Oncotype DX risk groups (P machine classifier trained to separate low/high Oncotype DX risk categories using the mitotic count determined by the DL classifier yielded a 83.19% classification accuracy. © 2017 International Society for Advancement of Cytometry. © 2017 International Society for Advancement of Cytometry.

The influence of serotonin on the mitotic rate in the colonic crypt epithelium and in colonic adenocarcinoma in rats.

Science.gov (United States)

Tutton, P J; Barkla, D H

1978-01-01

1. The mitotic rate in the crypts of Lieberkühn of the descending colon and in dimethylhydrazine-induced adenocarcinomata of the descending colon of rat was measured using a stathmokinetic technique. 2. Intraperitoneal injection of a small dose (10 microgram/kg) of serotonin resulted in an increase in the tumour cell mitotic rate. 3. Blockade of serotonin receptors by 2-bromolysergic acid diethylamide and depletion of tissue serotonin levels following injection of DL-6-fluorotryptophan both result in a decrease in the tumour cell mitotic rate. 4. Treatment with serotonin, 2-bromolysergic acid diethylamide and DL-6-fluorotryptophan were all without effect on the colonic crypt cell mitotic rate.

Current progress and future perspectives in the development of anti-polo-like kinase 1 therapeutic agents [version 1; referees: 4 approved

Directory of Open Access Journals (Sweden)

Jung-Eun Park

2017-06-01

Full Text Available Although significant levels of side effects are often associated with their use, microtubule-directed agents that primarily target fast-growing mitotic cells have been considered to be some of the most effective anti-cancer therapeutics. With the hope of developing new-generation anti-mitotic agents with reduced side effects and enhanced tumor specificity, researchers have targeted various proteins whose functions are critically required for mitotic progression. As one of the highly attractive mitotic targets, polo-like kinase 1 (Plk1 has been the subject of an extensive effort for anti-cancer drug discovery. To date, a variety of anti-Plk1 agents have been developed, and several of them are presently in clinical trials. Here, we will discuss the current status of generating anti-Plk1 agents as well as future strategies for designing and developing more efficacious anti-Plk1 therapeutics.

Interaction of low-dose irradiation with subsequent mutagenic treatment. Role of mitotic delay

International Nuclear Information System (INIS)

Salone, B.; Pretazzoli, V.; Bosi, A.; Olivieri, G.

1996-01-01

Experiments were carried out with human lymphocytes to test whether there was any relation between the changes that conditioning treatment can produce in cell progression or in mitotic delay induced by the challenge dose and the presence of an 'adaptive response' (AR). In experiments in which the cells were successively fixed after the challenge dose, the interaction between conditioning treatment and challenge was of the same sign for all the fixation times: therefore it is likely that modifications of the cytogenetic damage in primed cells is not a mere reflection of stage sensitivity. In experiments in which using 1 Gy as conditioning treatment we induced a drastic extension of G 2 , we did not observe any AR; therefore, even if conditioning treatment can induce modifications in the cell-cycle phases before and/or after challenge, there is probably no link between these modifications and the presence of an AR

Genetic variation in mitotic regulatory pathway genes is associated with breast tumor grade

DEFF Research Database (Denmark)

Purrington, Kristen S; Slettedahl, Seth; Bolla, Manjeet K

2014-01-01

polymorphisms (SNPs) from 194 mitotic genes and breast cancer risk, overall and by histologic grade, in the Breast Cancer Association Consortium (BCAC) iCOGS study (n = 39 067 cases; n = 42 106 controls). SNPs in TACC2 [rs17550038: odds ratio (OR) = 1.24, 95% confidence interval (CI) 1.16-1.33, P = 4.2 × 10......Mitotic index is an important component of histologic grade and has an etiologic role in breast tumorigenesis. Several small candidate gene studies have reported associations between variation in mitotic genes and breast cancer risk. We measured associations between 2156 single nucleotide......(-10)) and EIF3H (rs799890: OR = 1.07, 95% CI 1.04-1.11, P = 8.7 × 10(-6)) were significantly associated with risk of low-grade breast cancer. The TACC2 signal was retained (rs17550038: OR = 1.15, 95% CI 1.07-1.23, P = 7.9 × 10(-5)) after adjustment for breast cancer risk SNPs in the nearby FGFR2 gene...

Effect of insulin on the mitotic activity of bone marrow cells after irradiation. [Gamma radiation, rats

Energy Technology Data Exchange (ETDEWEB)

Barkalaya, A I

1976-02-01

A total of 236 white rats were given a whole-body gamma dose of 750 R. Part of the rats were given a subcutaneous insulin injection of 0.2 units/kg. After 10, 20, 30 min, 1, 2, 3, 5, 8, 10 and 12 hours the mitotic index was determined in both groups of rats in the bone marrow of the femur. The content of glucose and insulin in the blood was determined. The mitotic index was found to be higher on administering insulin. The use of insulin in radiation sickness intensifies the mitotic activity of bone marrow cells and stimulates the recovery of bone marrow hematopoiesis. 5 references.

Proteasome inhibition enhances the efficacy of volasertib-induced mitotic arrest in AML in vitro and prolongs survival in vivo.

Science.gov (United States)

Schnerch, Dominik; Schüler, Julia; Follo, Marie; Felthaus, Julia; Wider, Dagmar; Klingner, Kathrin; Greil, Christine; Duyster, Justus; Engelhardt, Monika; Wäsch, Ralph

2017-03-28

Elderly and frail patients, diagnosed with acute myeloid leukemia (AML) and ineligible to undergo intensive treatment, have a dismal prognosis. The small molecule inhibitor volasertib induces a mitotic block via inhibition of polo-like kinase 1 and has shown remarkable anti-leukemic activity when combined with low-dose cytarabine. We have demonstrated that AML cells are highly vulnerable to cell death in mitosis yet manage to escape a mitotic block through mitotic slippage by sustained proteasome-dependent slow degradation of cyclin B. Therefore, we tested whether interfering with mitotic slippage through proteasome inhibition arrests and kills AML cells more efficiently during mitosis. We show that therapeutic doses of bortezomib block the slow degradation of cyclin B during a volasertib-induced mitotic arrest in AML cell lines and patient-derived primary AML cells. In a xenotransplant mouse model of human AML, mice receiving volasertib in combination with bortezomib showed superior disease control compared to mice receiving volasertib alone, highlighting the potential therapeutic impact of this drug combination.

Plk1 inhibition causes post-mitotic DNA damage and senescence in a range of human tumor cell lines.

Directory of Open Access Journals (Sweden)

Denise L Driscoll

Full Text Available 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.

Early Statin Use and the Progression of Alzheimer Disease: A Total Population-Based Case-Control Study.

Science.gov (United States)

Lin, Feng-Cheng; Chuang, Yun-Shiuan; Hsieh, Hui-Min; Lee, Tzu-Chi; Chiu, Kuei-Fen; Liu, Ching-Kuan; Wu, Ming-Tsang

2015-11-01

The protective effect of statin on Alzheimer disease (AD) is still controversial, probably due to the debate about when to start the use of statin and the lack of any large-scale randomized evidence that actually supports the hypothesis. The purpose of this study was to examine the protective effect of early statin use on mild-to-moderate AD in the total Taiwanese population.This was a total population-based case-control study, using the total population of Taiwanese citizens seen in general medical practice; therefore, the findings can be applied to the general population. The study patients were those with newly diagnosed dementia (ICD-9 290.x) and prescribed any acetylcholinesterase inhibitors (AChEI) from the Taiwan National Health Insurance dataset in 1997 to 2008. The newly diagnosed eligible mild-to-moderate AD patients were traced from the dates of their index dates, which was defined as the first day to receive any AChEI treatment, back to 1 year (exposure period) to categorize them into AD with early statin use and without early statin use. Early statin use was defined as patients using statin before AChEI treatment. Alzheimer disease patients with early statin use were those receiving any statin treatment during the exposure period. Then, we used propensity-score-matched strategy to match these 2 groups as 1:1. The matched study patients were followed-up from their index dates. The primary outcome was the discontinuation of AChEI treatment, indicating AD progression.There were 719 mild-to-moderate AD-paired patients with early statin use and without early statin use for analyses. Alzheimer disease progression was statistically lower in AD patients with early statin use than those without (P = 0.00054). After adjusting for other covariates, mild-to-moderate AD patients with early stain use exhibited a 0.85-risk (95% CI = 0.76-0.95, P = 0.0066) to have AD progression than those without.Early statin use was significantly associated with a reduction in AD

A molecular mechanism of mitotic centrosome assembly in Drosophila

Science.gov (United States)

Conduit, Paul T; Richens, Jennifer H; Wainman, Alan; Holder, James; Vicente, Catarina C; Pratt, Metta B; Dix, Carly I; Novak, Zsofia A; Dobbie, Ian M; Schermelleh, Lothar; Raff, Jordan W

2014-01-01

Centrosomes comprise a pair of centrioles surrounded by pericentriolar material (PCM). The PCM expands dramatically as cells enter mitosis, but it is unclear how this occurs. In this study, we show that the centriole protein Asl initiates the recruitment of DSpd-2 and Cnn to mother centrioles; both proteins then assemble into co-dependent scaffold-like structures that spread outwards from the mother centriole and recruit most, if not all, other PCM components. In the absence of either DSpd-2 or Cnn, mitotic PCM assembly is diminished; in the absence of both proteins, it appears to be abolished. We show that DSpd-2 helps incorporate Cnn into the PCM and that Cnn then helps maintain DSpd-2 within the PCM, creating a positive feedback loop that promotes robust PCM expansion around the mother centriole during mitosis. These observations suggest a surprisingly simple mechanism of mitotic PCM assembly in flies. DOI: http://dx.doi.org/10.7554/eLife.03399.001 PMID:25149451

Drosophila MOF controls Checkpoint protein2 and regulates genomic stability during early embryogenesis.

Science.gov (United States)

Pushpavalli, Sreerangam N C V L; Sarkar, Arpita; Ramaiah, M Janaki; Chowdhury, Debabani Roy; Bhadra, Utpal; Pal-Bhadra, Manika

2013-01-24

In Drosophila embryos, checkpoints maintain genome stability by delaying cell cycle progression that allows time for damage repair or to complete DNA synthesis. Drosophila MOF, a member of MYST histone acetyl transferase is an essential component of male X hyperactivation process. Until recently its involvement in G2/M cell cycle arrest and defects in ionizing radiation induced DNA damage pathways was not well established. Drosophila MOF is highly expressed during early embryogenesis. In the present study we show that haplo-insufficiency of maternal MOF leads to spontaneous mitotic defects like mitotic asynchrony, mitotic catastrophe and chromatid bridges in the syncytial embryos. Such abnormal nuclei are eliminated and digested in the yolk tissues by nuclear fall out mechanism. MOF negatively regulates Drosophila checkpoint kinase 2 tumor suppressor homologue. In response to DNA damage the checkpoint gene Chk2 (Drosophila mnk) is activated in the mof mutants, there by causing centrosomal inactivation suggesting its role in response to genotoxic stress. A drastic decrease in the fall out nuclei in the syncytial embryos derived from mof¹/+; mnkp⁶/+ females further confirms the role of DNA damage response gene Chk2 to ensure the removal of abnormal nuclei from the embryonic precursor pool and maintain genome stability. The fact that mof mutants undergo DNA damage has been further elucidated by the increased number of single and double stranded DNA breaks. mof mutants exhibited genomic instability as evidenced by the occurance of frequent mitotic bridges in anaphase, asynchronous nuclear divisions, disruption of cytoskeleton, inactivation of centrosomes finally leading to DNA damage. Our findings are consistent to what has been reported earlier in mammals that; reduced levels of MOF resulted in increased genomic instability while total loss resulted in lethality. The study can be further extended using Drosophila as model system and carry out the interaction of MOF

Drosophila MOF controls Checkpoint protein2 and regulates genomic stability during early embryogenesis

Directory of Open Access Journals (Sweden)

Pushpavalli Sreerangam NCVL

2013-01-01

Full Text Available Abstract Background In Drosophila embryos, checkpoints maintain genome stability by delaying cell cycle progression that allows time for damage repair or to complete DNA synthesis. Drosophila MOF, a member of MYST histone acetyl transferase is an essential component of male X hyperactivation process. Until recently its involvement in G2/M cell cycle arrest and defects in ionizing radiation induced DNA damage pathways was not well established. Results Drosophila MOF is highly expressed during early embryogenesis. In the present study we show that haplo-insufficiency of maternal MOF leads to spontaneous mitotic defects like mitotic asynchrony, mitotic catastrophe and chromatid bridges in the syncytial embryos. Such abnormal nuclei are eliminated and digested in the yolk tissues by nuclear fall out mechanism. MOF negatively regulates Drosophila checkpoint kinase 2 tumor suppressor homologue. In response to DNA damage the checkpoint gene Chk2 (Drosophila mnk is activated in the mof mutants, there by causing centrosomal inactivation suggesting its role in response to genotoxic stress. A drastic decrease in the fall out nuclei in the syncytial embryos derived from mof1/+; mnkp6/+ females further confirms the role of DNA damage response gene Chk2 to ensure the removal of abnormal nuclei from the embryonic precursor pool and maintain genome stability. The fact that mof mutants undergo DNA damage has been further elucidated by the increased number of single and double stranded DNA breaks. Conclusion mof mutants exhibited genomic instability as evidenced by the occurance of frequent mitotic bridges in anaphase, asynchronous nuclear divisions, disruption of cytoskeleton, inactivation of centrosomes finally leading to DNA damage. Our findings are consistent to what has been reported earlier in mammals that; reduced levels of MOF resulted in increased genomic instability while total loss resulted in lethality. The study can be further extended using

Single-walled carbon nanotube-induced mitotic disruption⋆

OpenAIRE

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.

2011-01-01

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 c...

The Drosophila Microtubule-Associated Protein Mars Stabilizes Mitotic Spindles by Crosslinking Microtubules through Its N-Terminal Region

DEFF Research Database (Denmark)

Zhang, Gang; Beati, Hamze; Nilsson, Jakob

2013-01-01

Correct segregation of genetic material relies on proper assembly and maintenance of the mitotic spindle. How the highly dynamic microtubules (MTs) are maintained in stable mitotic spindles is a key question to be answered. Motor and non-motor microtubule associated proteins (MAPs) have been...

Sequential phosphorylation of GRASP65 during mitotic Golgi disassembly

Directory of Open Access Journals (Sweden)

Danming Tang

2012-09-01

GRASP65 phosphorylation during mitosis and dephosphorylation after mitosis are required for Golgi disassembly and reassembly during the cell cycle. At least eight phosphorylation sites on GRASP65 have been identified, but whether they are modified in a coordinated fashion during mitosis is so far unknown. In this study, we raised phospho-specific antibodies that recognize phosphorylated T220/T224, S277 and S376 residues of GRASP65, respectively. Biochemical analysis showed that cdc2 phosphorylates all three sites, while plk1 enhances the phosphorylation. Microscopic studies using these antibodies for double and triple labeling demonstrate sequential phosphorylation and dephosphorylation during the cell cycle. S277 and S376 are phosphorylated from late G2 phase through metaphase until telophase when the new Golgi is reassembled. T220/224 is not modified until prophase, but is highly modified from prometaphase to anaphase. In metaphase, phospho-T220/224 signal localizes on both Golgi haze and mitotic Golgi clusters that represent dispersed Golgi vesicles and Golgi remnants, respectively, while phospho-S277 and S376 labeling is more concentrated on mitotic Golgi clusters. Expression of a phosphorylation-resistant GRASP65 mutant T220A/T224A inhibited mitotic Golgi fragmentation to a much larger extent than the expression of the S277A and S376A mutants. In cytokinesis, T220/224 dephosphorylation occurs prior to that of S277, but after S376. This study provides evidence that GRASP65 is sequentially phosphorylated and dephosphorylated during mitosis at different sites to orchestrate Golgi disassembly and reassembly during cell division, with phosphorylation of the T220/224 site being most critical in the process.

Magic with moulds: Meiotic and mitotic crossing over in Neurospora ...

Indian Academy of Sciences (India)

2006-02-16

Feb 16, 2006 ... Home; Journals; Journal of Biosciences; Volume 31; Issue 1. Commentary: Magic with moulds: Meiotic and mitotic crossing over in Neurospora inversions and duplications. Durgadas P Kasbekar. Volume 31 Issue 1 March 2006 pp 3-4 ...

Fully functional global genome repair of (6-4) photoproducts and compromised transcription-coupled repair of cyclobutane pyrimidine dimers in condensed mitotic chromatin

Energy Technology Data Exchange (ETDEWEB)

Komura, Jun-ichiro, E-mail: junkom@med.tohoku.ac.jp [Department of Cell Biology, Tohoku University Graduate School of Medicine, Sendai 980-8575 (Japan); Ikehata, Hironobu [Department of Cell Biology, Tohoku University Graduate School of Medicine, Sendai 980-8575 (Japan); Mori, Toshio [Radioisotope Research Center, Nara Medical University, Kashihara, Nara 634-8521 (Japan); Ono, Tetsuya [Department of Cell Biology, Tohoku University Graduate School of Medicine, Sendai 980-8575 (Japan)

2012-03-10

During mitosis, chromatin is highly condensed, and activities such as transcription and semiconservative replication do not occur. Consequently, the condensed condition of mitotic chromatin is assumed to inhibit DNA metabolism by impeding the access of DNA-transacting proteins. However, about 40 years ago, several researchers observed unscheduled DNA synthesis in UV-irradiated mitotic chromosomes, suggesting the presence of excision repair. We re-examined this subject by directly measuring the removal of UV-induced DNA lesions by an ELISA and by a Southern-based technique in HeLa cells arrested at mitosis. We observed that the removal of (6-4) photoproducts from the overall genome in mitotic cells was as efficient as in interphase cells. This suggests that global genome repair of (6-4) photoproducts is fully functional during mitosis, and that the DNA in mitotic chromatin is accessible to proteins involved in this mode of DNA repair. Nevertheless, not all modes of DNA repair seem fully functional during mitosis. We also observed that the removal of cyclobutane pyrimidine dimers from the dihydrofolate reductase and c-MYC genes in mitotic cells was very slow. This suggests that transcription-coupled repair of cyclobutane pyrimidine dimers is compromised or non-functional during mitosis, which is probably the consequence of mitotic transcriptional repression. -- Highlights: Black-Right-Pointing-Pointer Global genome repair of (6-4) photoproducts is fully active in mitotic cells. Black-Right-Pointing-Pointer DNA in condensed mitotic chromatin does not seem inaccessible or inert. Black-Right-Pointing-Pointer Mitotic transcriptional repression may impair transcription-coupled repair.

Fully functional global genome repair of (6-4) photoproducts and compromised transcription-coupled repair of cyclobutane pyrimidine dimers in condensed mitotic chromatin

International Nuclear Information System (INIS)

Komura, Jun-ichiro; Ikehata, Hironobu; Mori, Toshio; Ono, Tetsuya

2012-01-01

During mitosis, chromatin is highly condensed, and activities such as transcription and semiconservative replication do not occur. Consequently, the condensed condition of mitotic chromatin is assumed to inhibit DNA metabolism by impeding the access of DNA-transacting proteins. However, about 40 years ago, several researchers observed unscheduled DNA synthesis in UV-irradiated mitotic chromosomes, suggesting the presence of excision repair. We re-examined this subject by directly measuring the removal of UV-induced DNA lesions by an ELISA and by a Southern-based technique in HeLa cells arrested at mitosis. We observed that the removal of (6-4) photoproducts from the overall genome in mitotic cells was as efficient as in interphase cells. This suggests that global genome repair of (6-4) photoproducts is fully functional during mitosis, and that the DNA in mitotic chromatin is accessible to proteins involved in this mode of DNA repair. Nevertheless, not all modes of DNA repair seem fully functional during mitosis. We also observed that the removal of cyclobutane pyrimidine dimers from the dihydrofolate reductase and c-MYC genes in mitotic cells was very slow. This suggests that transcription-coupled repair of cyclobutane pyrimidine dimers is compromised or non-functional during mitosis, which is probably the consequence of mitotic transcriptional repression. -- Highlights: ► Global genome repair of (6-4) photoproducts is fully active in mitotic cells. ► DNA in condensed mitotic chromatin does not seem inaccessible or inert. ► Mitotic transcriptional repression may impair transcription-coupled repair.

Human papillomavirus type 16 E7 oncoprotein engages but does not abrogate the mitotic spindle assembly checkpoint

Energy Technology Data Exchange (ETDEWEB)

Yu, Yueyang [Division of Infectious Diseases, Brigham and Women' s Hospital and Biological and Biomedical Sciences Program, Harvard Medical School, Boston, MA 02115 (United States); Munger, Karl, E-mail: kmunger@rics.bwh.harvard.edu [Division of Infectious Diseases, Brigham and Women' s Hospital and Biological and Biomedical Sciences Program, Harvard Medical School, Boston, MA 02115 (United States)

2012-10-10

The mitotic spindle assembly checkpoint (SAC) ensures faithful chromosome segregation during mitosis by censoring kinetochore-microtubule interactions. It is frequently rendered dysfunctional during carcinogenesis causing chromosome missegregation and genomic instability. There are conflicting reports whether the HPV16 E7 oncoprotein drives chromosomal instability by abolishing the SAC. Here we report that degradation of mitotic cyclins is impaired in cells with HPV16 E7 expression. RNAi-mediated depletion of Mad2 or BubR1 indicated the involvement of the SAC, suggesting that HPV16 E7 expression causes sustained SAC engagement. Mutational analyses revealed that HPV16 E7 sequences that are necessary for retinoblastoma tumor suppressor protein binding as well as sequences previously implicated in binding the nuclear and mitotic apparatus (NuMA) protein and in delocalizing dynein from the mitotic spindle contribute to SAC engagement. Importantly, however, HPV16 E7 does not markedly compromise the SAC response to microtubule poisons.

Cell synchrony techniques. I. A comparison of methods

Energy Technology Data Exchange (ETDEWEB)

Grdina, D.J.; Meistrich, M.L.; Meyn, R.E.; Johnson, T.S.; White, R.A.

1984-01-01

Selected cell synchrony techniques, as applied to asynchronous populations of Chinese hamster ovary (CHO) cells, have been compared. Aliquots from the same culture of exponentially growing cells were synchronized using mitotic selection, mitotic selection and hydroxyurea block, centrifugal elutriation, or an EPICS V cell sorter. Sorting of cells was achieved after staining cells with Hoechst 33258. After syncronization by the various methods the relative distribution of cells in G/sub 1/, S, or G/sub 2/ + M phases of the cell cycle was determined by flow cytometry. Fractions of synchronized cells obtained from each method were replated and allowed to progress through a second cell cycle. Mitotic selection gave rise to relatively pure and unperturbed early G/sub 1/ phase cells. While cell synchrony rapidly dispersed with time, cells progressed through the cell cycle in 12 hr. Sorting with the EPIC V on the modal G/sub 1/ peak yielded a relatively pure but heterogeneous G/sub 1/ population (i.e. early to late G/sub 1/). Again, synchrony dispersed with time, but cell-cycle progression required 14 hr. With centrifugal elutriation, several different cell populations synchronized throughout the cell cycle could be rapidly obtained with a purity comparable to mitotic selection and cell sorting. It was concluded that, either alone or in combination with blocking agents such as hydroxyurea, elutriation and mitotic selection were both excellent methods for synchronizing CHO cells. Cell sorting exhibited limitations in sample size and time required for synchronizing CHO cells. Its major advantage would be its ability to isolate cell populations unique with respect to selected cellular parameters. 19 references, 9 figures.

Effects of whole-body and partial-body x irradiation upon epidermal mitotic activity during wound healing in mouse skin

International Nuclear Information System (INIS)

Kobayashi, K.

1977-01-01

Mitotic activity of normal (unwounded) and wounded skin was measured in the control (nonirradiated) and whole-body or partial-body x-irradiated mouse. Higher mitotic activity in the anterior than in the posterior region of the body was found in both the normal and the wounded skin of the control mouse. Whole-body irradiation (500 R) depressed completely the mitotic activity of normal skin 2 to 4 days after irradiation. In spite of this depression in mitotic activity, a surgical incision made 1 to 3 days after irradiation could induce a burst of proliferation after an inhibition of an initial mitosis increase. When the animals were partially irradiated with 500 R 3 days before wounding, it was shown that mitosis at 24 hr after wounding was inhibited markedly by the local effect of irradiation and that mitosis also could be inhibited diversely by the abscopal effect of irradiation. Because of a close similarity of sequential mitotic patterns between whole-body-irradiated and flapped-skin-only-irradiated groups (direct irradiation), the effect of irradiation upon mitosis was considered to be primarily local. Some discussions were made concerning the possible reasons which made a difference in mitotic patterns between the head-only-irradiated group, the irradiated group including the head and other parts of the body except for the skin flap

Relationships betwen mitotic delay and the dose rate of X radiation

International Nuclear Information System (INIS)

Yi, P.N.; Rha, C.K.; Evans, H.H.; Beer, J.Z.

1994-01-01

Upon exposure of cells to radiation delivered at a continuous low dose rate, cell proliferation may be sustained with the cells exhibiting a constant doubling time that is independent of the total dose. The doubling time or mitotic delay under these conditions has been shown to depend on the dose rate in HeLa, V79 and P388F cells. Reanalysis of the data for these particular cell lines shows that there is a threshold dose rate for mitotic delay, and that above the threshold there is a linear relationship between the length of mitotic delay and the logarithm of the dose rate which is referred to as the dose-rate response. We have observed the same relationships for L5178Y (LY)-R and LY-S cells exposed to low-dose-rate radiation. The threshold dose rates for LY-R, LY-S and P388F cells are similar (0.01-0.02 Gy/h) and are much lower than for V79 and HeLa cells. The slope of the dose-rate response curve is the greatest for HeLa cells, followed in order by LY-S, V79 and P388F cells, and finally by LY-R cells. The slopes for HeLa and LY-R cells differ by a factor of 35. 20 refs., 3 figs., 1 tab

Determining local and contextual features describing appearance of difficult to identify mitotic figures

Science.gov (United States)

Gandomkar, Ziba; Brennan, Patrick C.; Mello-Thoms, Claudia

2017-03-01

Mitotic count is helpful in determining the aggressiveness of breast cancer. In previous studies, it was shown that the agreement among pathologists for grading mitotic index is fairly modest, as mitoses have a large variety of appearances and they could be mistaken for other similar objects. In this study, we determined local and contextual features that differ significantly between easily identifiable mitoses and challenging ones. The images were obtained from the Mitosis-Atypia 2014 challenge. In total, the dataset contained 453 mitotic figures. Two pathologists annotated each mitotic figure. In case of disagreement, an opinion from a third pathologist was requested. The mitoses were grouped into three categories, those recognized as "a true mitosis" by both pathologists ,those labelled as "a true mitosis" by only one of the first two readers and also the third pathologist, and those annotated as "probably a mitosis" by all readers or the majority of them. After color unmixing, the mitoses were segmented from H channel. Shape-based features along with intensity-based and textural features were extracted from H-channel, blue ratio channel and five different color spaces. Holistic features describing each image were also considered. The Kruskal-Wallis H test was used to identify significantly different features. Multiple comparisons were done using the rank-based version of Tukey-Kramer test. The results indicated that there are local and global features which differ significantly among different groups. In addition, variations between mitoses in different groups were captured in the features from HSL and LCH color space more than other ones.

Genetic control of mitotic crossing over in yeast. 2. Influence of UV irradiation

International Nuclear Information System (INIS)

Zakharov, I.A.; Marfin, S.V.; Koval'tsova, S.V.; Kasinova, G.V.

1982-01-01

UV-induced crossing-over and general mitotic segregation of the following strains of Saccharomyces cerevisiae yeasts were studied: a wild-type diploid, diploids homozygous with respect to the radiosensitivity of rad 2, rad 15, rad 54, xrs 4, rad 2 rad 54, rad 15 rad 54. Wild-type diploids rad 2 and rad 15 have a high frequency of the induced mitotic crossing-over. Diploids rad 15, rad 54 can not cause UV-induced mitotic crossing-over. Reddish-pink and reddish-pink-white colonies ratio (the first appear if the crossing-over occurs during the first after the irradiation division, the second - during the second division) is 4.8:1 for the wild type, 1.6:1 for rad 2, and 1.1:1 for rad 15. Nonreciprocal mitotic segregation of high frequency was observed for the wild type rad 2, rad 15, xrs 4, and diploids rad 54, rad 2 rad 54, rad 15 rad 54 had a lower frequency. We suppose that after UV-irradiation there exist at least three types of repair in yeast diploid cells: excision repair, prereplication recombinating repair after the excision of dimers, and post-replication recombinating repair. Rad 2 and rad 15 mutations blow the first and second types, rad 54 mutation partially block the second and third parths. It seems that xrs 4 mutation does not block the recombinating capability but somehow changes the process of recombination in such a way that much nonreciprocal products recorded as seqregants are produced [ru

Drug-induced premature chromosome condensation (PCC) protocols: cytogenetic approaches in mitotic chromosome and interphase chromatin.

Science.gov (United States)

Gotoh, Eisuke

2015-01-01

Chromosome analysis is a fundamental technique which is used in wide areas of cytogenetic study including karyotyping species, hereditary diseases diagnosis, or chromosome biology study. Chromosomes are usually prepared from mitotic cells arrested by colcemid block protocol. However, obtaining mitotic chromosomes is often hampered under several circumstances. As a result, cytogenetic analysis will be sometimes difficult or even impossible in such cases. Premature chromosome condensation (PCC) (see Note 1) is an alternative method that has proved to be a unique and useful way in chromosome analysis. Former, PCC has been achieved following cell fusion method (cell-fusion PCC) mediated either by fusogenic viruses (e.g., Sendai virus) or cell fusion chemicals (e.g., polyethylene glycol), but the cell fusion PCC has several drawbacks. The novel drug-induced PCC using protein phosphatase inhibitors was introduced about 20 years ago. This method is much simpler and easier even than the conventional mitotic chromosome preparation protocol use with colcemid block and furthermore obtained PCC index (equivalent to mitotic index for metaphase chromosome) is usually much higher than colcemid block method. Moreover, this method allows the interphase chromatin to be condensed to visualize like mitotic chromosomes. Therefore drug-induced PCC has opened the way for chromosome analysis not only in metaphase chromosomes but also in interphase chromatin. The drug-induced PCC has thus proven the usefulness in cytogenetics and other cell biology fields. For this second edition version, updated modifications/changes are supplemented in Subheadings 2, 3, and 4, and a new section describing the application of PCC in chromosome science fields is added with citation of updated references.

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

International Nuclear Information System (INIS)

Rubin, N.A.

1980-01-01

All mitotically active normal tissues in mammals investigated to date demonstrate a circadian rhythm in cell division. The murine corneal epithelium is a practical and advantageous tissue model for studying this phenomenon. In animals synchronized to a light-dark (LD) schedule, one sees predictably reproducible occurrences of peaks and troughs in the mitotic index (MI) within each 24-hour (h) period. One of the harmful effects of ionizing radiation on dividing cells is mitotic delay, reported to be a G 2 block in cells approaching mitosis. Affected cells are not killed but are inhibited from entering mitosis and are delayed for a span of time reported to be dose and cell cycle dependent. In the classical description of mitotic delay, MI of irradiated cells begins to drop in relation to the control, which is plotted as a straight line, uniform throughout the experiment. After the damage is repaired, delayed cells can enter mitosis along with other cells in the pool unaffected by the radiation, resulting in a MI higher than control levels. The span of delay and the occurrence of recovery are assumed to be constant for a given dose and tissue under similar experimental conditions. First described in asynchronously-dividing tissue culture cells, this concept is also extrapolated to the in vivo situation

Early CT signs of progressive hemorrhagic injury following acute traumatic brain injury

Energy Technology Data Exchange (ETDEWEB)

Tong, Wu-song; Zheng, Ping; Xu, Jun-fa; Guo, Yi-jun; Zeng, Jing-song; Yang, Wen-jin; Li, Gao-yi; He, Bin; Yu, Hui [Pudong New Area People' s Hospital, Department of Neurosurgery, Shanghai (China)

2011-05-15

Since progressive hemorrhagic injury (PHI) was introduced in neurosurgical literatures, several studies have been performed, the results of which have influenced doctors but do not define guidelines for the best treatment of PHI. PHI may be confirmed by a serial computerized tomography (CT) scan, and it has been shown to be associated with a fivefold increase in the risk of clinical worsening and is a significant cause of morbidity and mortality as well. So, early detection of PHI is practically important in a clinical situation. To analyze the early CT signs of progressive hemorrhagic injury following acute traumatic brain injury (TBI) and explore their clinical significances, PHI was confirmed by comparing the first and repeated CT scans. Data were analyzed and compared including times from injury to the first CT and signs of the early CT scan. Logistic regression analysis was used to show the risk factors related to PHI. A cohort of 630 TBI patients was evaluated, and there were 189 (30%) patients who suffered from PHI. For patients with their first CT scan obtained as early as 2 h post-injury, there were 116 (77.25%) cases who suffered from PHI. The differences between PHIs and non-PHIs were significant in the initial CT scans showing fracture, subarachnoid hemorrhage (SAH), brain contusion, epidural hematoma (EDH), subdural hematoma (SDH), and multiple hematoma as well as the times from injury to the first CT scan (P < 0.01). Logistic regression analysis showed that early CT scans (EDH, SDH, SAH, fracture, and brain contusion) were predictors of PHI (P < 0.01). For patients with the first CT scan obtained as early as 2 h post-injury, a follow-up CT scan should be performed promptly. If the initial CT scan shows SAH, brain contusion, and primary hematoma with brain swelling, an earlier and dynamic CT scan should be performed for detection of PHI as early as possible and the medical intervention would be enforced in time. (orig.)

Early CT signs of progressive hemorrhagic injury following acute traumatic brain injury

International Nuclear Information System (INIS)

Tong, Wu-song; Zheng, Ping; Xu, Jun-fa; Guo, Yi-jun; Zeng, Jing-song; Yang, Wen-jin; Li, Gao-yi; He, Bin; Yu, Hui

2011-01-01

Since progressive hemorrhagic injury (PHI) was introduced in neurosurgical literatures, several studies have been performed, the results of which have influenced doctors but do not define guidelines for the best treatment of PHI. PHI may be confirmed by a serial computerized tomography (CT) scan, and it has been shown to be associated with a fivefold increase in the risk of clinical worsening and is a significant cause of morbidity and mortality as well. So, early detection of PHI is practically important in a clinical situation. To analyze the early CT signs of progressive hemorrhagic injury following acute traumatic brain injury (TBI) and explore their clinical significances, PHI was confirmed by comparing the first and repeated CT scans. Data were analyzed and compared including times from injury to the first CT and signs of the early CT scan. Logistic regression analysis was used to show the risk factors related to PHI. A cohort of 630 TBI patients was evaluated, and there were 189 (30%) patients who suffered from PHI. For patients with their first CT scan obtained as early as 2 h post-injury, there were 116 (77.25%) cases who suffered from PHI. The differences between PHIs and non-PHIs were significant in the initial CT scans showing fracture, subarachnoid hemorrhage (SAH), brain contusion, epidural hematoma (EDH), subdural hematoma (SDH), and multiple hematoma as well as the times from injury to the first CT scan (P < 0.01). Logistic regression analysis showed that early CT scans (EDH, SDH, SAH, fracture, and brain contusion) were predictors of PHI (P < 0.01). For patients with the first CT scan obtained as early as 2 h post-injury, a follow-up CT scan should be performed promptly. If the initial CT scan shows SAH, brain contusion, and primary hematoma with brain swelling, an earlier and dynamic CT scan should be performed for detection of PHI as early as possible and the medical intervention would be enforced in time. (orig.)

The participation of elevated levels of cyclic GMP in the recovery from radiation-induced mitotic delay

International Nuclear Information System (INIS)

Daniel, J.W.; Oleinick, N.L.

1984-01-01

The levels of cyclic AMP and cyclic GMP have been measured in Physarum plasmodia before and after treatment with gamma-radiation, 2 mM caffeine, or combinations of the two agents compared to the length of the radiation-induced mitotic delay. Caffeine alone produces a rapid transient elevation of cyclic AMP and a slower delayed elevation of cyclic GMP. Irradiation elicits an immediate transient increase in cyclic AMP and a later cyclic GMP increase which accompanies or precedes the delayed mitosis. A composite pattern is produced by combinations of radiation and caffeine, a distinctive feature of which is an elevated level of cyclic GMP near the time of the radiation-delayed and caffeine-promoted mitosis. With pretreatment by caffeine, the least radiation-induced mitotic delay occurs when plasmodia are irradiated during the caffeine-elicited increase in cyclic GMP. The plasmodium becomes refractory to the reduction of mitotic delay by caffeine at approximately the time it becomes refractory to the further elevation of cyclic GMP by caffeine. The data support a role for cyclic AMP in the onset of and for cyclic GMP in the recovery from mitotic delay induced by ionizing radiation. (author)

Cdc20 control of cell fate during prolonged mitotic arrest

DEFF Research Database (Denmark)

Nilsson, Jakob

2011-01-01

The fate of cells arrested in mitosis by antimitotic compounds is complex but is influenced by competition between pathways promoting cell death and pathways promoting mitotic exit. As components of both of these pathways are regulated by Cdc20-dependent degradation, I hypothesize that variations...

Taxifolin enhances andrographolide-induced mitotic arrest and apoptosis in human prostate cancer cells via spindle assembly checkpoint activation.

Directory of Open Access Journals (Sweden)

Zhong Rong Zhang

Full Text Available Andrographolide (Andro suppresses proliferation and triggers apoptosis in many types of cancer cells. Taxifolin (Taxi has been proposed to prevent cancer development similar to other dietary flavonoids. In the present study, the cytotoxic and apoptotic effects of the addition of Andro alone and Andro and Taxi together on human prostate carcinoma DU145 cells were assessed. Andro inhibited prostate cancer cell proliferation by mitotic arrest and activation of the intrinsic apoptotic pathway. Although the effect of Taxi alone on DU145 cell proliferation was not significant, the combined use of Taxi with Andro significantly potentiated the anti-proliferative effect of increased mitotic arrest and apoptosis by enhancing the cleavage of poly(ADP-ribose polymerase, and caspases-7 and -9. Andro together with Taxi enhanced microtubule polymerization in vitro, and they induced the formation of twisted and elongated spindles in the cancer cells, thus leading to mitotic arrest. In addition, we showed that depletion of MAD2, a component in the spindle assembly checkpoint (SAC, alleviated the mitotic block induced by the two compounds, suggesting that they trigger mitotic arrest by SAC activation. This study suggests that the anti-cancer activity of Andro can be significantly enhanced in combination with Taxi by disrupting microtubule dynamics and activating the SAC.

Taxifolin Enhances Andrographolide-Induced Mitotic Arrest and Apoptosis in Human Prostate Cancer Cells via Spindle Assembly Checkpoint Activation

Science.gov (United States)

Wong, Matthew Man-Kin; Chiu, Sung-Kay; Cheung, Hon-Yeung

2013-01-01

Andrographolide (Andro) suppresses proliferation and triggers apoptosis in many types of cancer cells. Taxifolin (Taxi) has been proposed to prevent cancer development similar to other dietary flavonoids. In the present study, the cytotoxic and apoptotic effects of the addition of Andro alone and Andro and Taxi together on human prostate carcinoma DU145 cells were assessed. Andro inhibited prostate cancer cell proliferation by mitotic arrest and activation of the intrinsic apoptotic pathway. Although the effect of Taxi alone on DU145 cell proliferation was not significant, the combined use of Taxi with Andro significantly potentiated the anti-proliferative effect of increased mitotic arrest and apoptosis by enhancing the cleavage of poly(ADP-ribose) polymerase, and caspases-7 and -9. Andro together with Taxi enhanced microtubule polymerization in vitro, and they induced the formation of twisted and elongated spindles in the cancer cells, thus leading to mitotic arrest. In addition, we showed that depletion of MAD2, a component in the spindle assembly checkpoint (SAC), alleviated the mitotic block induced by the two compounds, suggesting that they trigger mitotic arrest by SAC activation. This study suggests that the anti-cancer activity of Andro can be significantly enhanced in combination with Taxi by disrupting microtubule dynamics and activating the SAC. PMID:23382917

Effects of polyamines and polyamine biosynthetic inhibitors on mitotic activity of Allium cepa root tips.

Science.gov (United States)

Unal, Meral; Palavan-Unsal, Narcin; Tufekci, M A

2008-03-01

The genotoxic and cytotoxic effects of exogenous polyamines (PAs), putrescine (Put), spermidine (Spd), spermine (Spm) and PA biosynthetic inhibitors, alpha-difluoromethylornithine (DFMO), cyclohexilamine (CHA), methylglioxal bis-(guanylhydrazone) (MGBG) were investigated in the root meristems of Allium cepa L. The reduction of mitotic index and the induction of chromosomal aberrations such as bridges, stickiness, c-mitotic anaphases, micronuclei, endoredupliction by PAs and PA biosynthetic inhibitors were observed and these were used as evidence of genotoxicity and cytotoxicity.

Kalanchoe tubiflora extract inhibits cell proliferation by affecting the mitotic apparatus.

Science.gov (United States)

Hsieh, Yi-Jen; Yang, Ming-Yeh; Leu, Yann-Lii; Chen, Chinpiao; Wan, Chin-Fung; Chang, Meng-Ya; Chang, Chih-Jui

2012-09-10

Kalanchoe tubiflora (KT) is a succulent plant native to Madagascar, and is commonly used as a medicinal agent in Southern Brazil. The underlying mechanisms of tumor suppression are largely unexplored. Cell viability and wound-healing were analyzed by MTT assay and scratch assay respectively. Cell cycle profiles were analyzed by FACS. Mitotic defects were analyzed by indirect immunofluoresence images. An n-Butanol-soluble fraction of KT (KT-NB) was able to inhibit cell proliferation. After a 48 h treatment with 6.75 μg/ml of KT, the cell viability was less than 50% of controls, and was further reduced to less than 10% at higher concentrations. KT-NB also induced an accumulation of cells in the G2/M phase of the cell cycle as well as an increased level of cells in the subG1 phase. Instead of disrupting the microtubule network of interphase cells, KT-NB reduced cell viability by inducing multipolar spindles and defects in chromosome alignment. KT-NB inhibits cell proliferation and reduces cell viability by two mechanisms that are exclusively involved with cell division: first by inducing multipolarity; second by disrupting chromosome alignment during metaphase. KT-NB reduced cell viability by exclusively affecting formation of the proper structure of the mitotic apparatus. This is the main idea of the new generation of anti-mitotic agents. All together, KT-NB has sufficient potential to warrant further investigation as a potential new anticancer agent candidate.

Early detection of emphysema progression

DEFF Research Database (Denmark)

Gorbunova, Vladlena; Jacobs, Sander S A M; Lo, Pechin

2010-01-01

Emphysema is one of the most widespread diseases in subjects with smoking history. The gold standard method for estimating the severity of emphysema is a lung function test, such as forced expiratory volume in first second (FEV1). However, several clinical studies showed that chest CT scans offer...... more sensitive estimates of emphysema progression. The standard CT densitometric score of emphysema is the relative area of voxels below a threshold (RA). The RA score is a global measurement and reflects the overall emphysema progression. In this work, we propose a framework for estimation of local...... emphysema progression from longitudinal chest CT scans. First, images are registered to a common system of coordinates and then local image dissimilarities are computed in corresponding anatomical locations. Finally, the obtained dissimilarity representation is converted into a single emphysema progression...

Flow cytometric analysis of mitotic cycle perturbation by chemical carcinogens in cultured epithelial cells. [Effects of benzo(a)pyrene-diol-epoxide on mitotic cycle of cultural mouse liver epithelial cells

Energy Technology Data Exchange (ETDEWEB)

Pearlman, Andrew Leonard [Univ. of California, Berkeley, CA (United States)

1978-08-01

A system for kinetic analysis of mitotic cycle perturbation by various agents was developed and applied to the study of the mitotic cycle effects and dependency of the chemical carcinogen benzo(a)pyrene-diolepoxide, DE, upon a mouse lever epithelial cell line, NMuLi. The study suggests that the targets of DE action are not confined to DNA alone but may include cytoplasmic structures as well. DE was found to affect cells located in virtually every phase of the mitotic cycle, with cells that were actively synthesizing DNA showing the strongest response. However, the resulting perturbations were not confined to S-phase alone. DE slowed traversal through S-phase by about 40% regardless of the cycle phase of the cells exposed to it, and slowed traversal through G₂M by about 50%. When added to G₁ cells, DE delayed recruitment of apparently quiescent (G₀) cells by 2 hours, and reduced the synchrony of the cohort of cells recruited into active proliferation. The kinetic analysis system consists of four elements: tissue culture methods for propagating and harvesting cell populations; an elutriation centrifugation system for bulk synchronization of cells in various phases of the mitotic cycle; a flow cytometer (FCM), coupled with appropriate staining protocols, to enable rapid analysis of the DNA distribution of any given cell population; and data reduction and analysis methods for extracting information from the DNA histograms produced by the FCM. The elements of the system are discussed. A mathematical analysis of DNA histograms obtained by FCM is presented. The analysis leads to the detailed implementation of a new modeling approach. The new modeling approach is applied to the estimation of cell cycle kinetic parameters from time series of DNA histograms, and methods for the reduction and interpretation of such series are suggested.

Regulatory dephosphorylation of CDK at G₂/M in plants: yeast mitotic phosphatase cdc25 induces cytokinin-like effects in transgenic tobacco morphogenesis.

Science.gov (United States)

Lipavská, Helena; Masková, Petra; Vojvodová, Petra

2011-05-01

During the last three decades, the cell cycle and its control by cyclin-dependent kinases (CDKs) have been extensively studied in eukaryotes. This endeavour has produced an overall picture that basic mechanisms seem to be largely conserved among all eukaryotes. The intricate regulation of CDK activities includes, among others, CDK activation by CDC25 phosphatase at G₂/M. In plants, however, studies of this regulation have lagged behind as a plant Cdc25 homologue or other unrelated phosphatase active at G₂/M have not yet been identified. Failure to identify a plant mitotic CDK activatory phosphatase led to characterization of the effects of alien cdc25 gene expression in plants. Tobacco, expressing the Schizosaccharomyces pombe mitotic activator gene, Spcdc25, exhibited morphological, developmental and biochemical changes when compared with wild type (WT) and, importantly, increased CDK dephosphorylation at G₂/M. Besides changes in leaf shape, internode length and root development, in day-neutral tobacco there was dramatically earlier onset of flowering with a disturbed acropetal floral capacity gradient typical of WT. In vitro, de novo organ formation revealed substantially earlier and more abundant formation of shoot primordia on Spcdc25 tobacco stem segments grown on shoot-inducing media when compared with WT. Moreover, in contrast to WT, stem segments from transgenic plants formed shoots even without application of exogenous growth regulator. Spcdc25-expressing BY-2 cells exhibited a reduced mitotic cell size due to a shortening of the G₂ phase together with high activity of cyclin-dependent kinase, NtCDKB1, in early S-phase, S/G₂ and early M-phase. Spcdc25-expressing tobacco ('Samsun') cell suspension cultures showed a clustered, more circular, cell phenotype compared with chains of elongated WT cells, and increased content of starch and soluble sugars. Taken together, Spcdc25 expression had cytokinin-like effects on the characteristics studied

Kinesin-8 effects on mitotic microtubule dynamics contribute to spindle function in fission yeast

Science.gov (United States)

Gergely, Zachary R.; Crapo, Ammon; Hough, Loren E.; McIntosh, J. Richard; Betterton, Meredith D.

2016-01-01

Kinesin-8 motor proteins destabilize microtubules. Their absence during cell division is associated with disorganized mitotic chromosome movements and chromosome loss. Despite recent work studying effects of kinesin-8s on microtubule dynamics, it remains unclear whether the kinesin-8 mitotic phenotypes are consequences of their effect on microtubule dynamics, their well-established motor activity, or additional, unknown functions. To better understand the role of kinesin-8 proteins in mitosis, we studied the effects of deletion of the fission yeast kinesin-8 proteins Klp5 and Klp6 on chromosome movements and spindle length dynamics. Aberrant microtubule-driven kinetochore pushing movements and tripolar mitotic spindles occurred in cells lacking Klp5 but not Klp6. Kinesin-8–deletion strains showed large fluctuations in metaphase spindle length, suggesting a disruption of spindle length stabilization. Comparison of our results from light microscopy with a mathematical model suggests that kinesin-8–induced effects on microtubule dynamics, kinetochore attachment stability, and sliding force in the spindle can explain the aberrant chromosome movements and spindle length fluctuations seen. PMID:27146110

Late A-bomb effects on proliferation and mitotic inhibition of T- and B-lymphocytes

Energy Technology Data Exchange (ETDEWEB)

Suzuki, Kazuo; Yoshimoto, Yasuhiko; Sasagawa, Sumiko; Sakatani, Tatsuichiro; Macchi, M; Fujikura, Toshio; Pirofsky, B; Hamada, Tadao

1984-11-01

In order to investigate late effects of ionization radiation and aging on T- and B-lymphocytes, mitotic ability of T- and B-lymphocytes in the peripheral blood of 266 A-bomb survivors was examined by determining the incorporation of (/sup 3/H)-thymidine. Phytohemagglutinin (PHA) and pokeweed mitogen (PWM) were used as inducers. Furthermore, mitotic inhibition of lymphocytes induced by a lymphatic inhibitor which was in part prepared from ulex seed extracts (USE) was examined. A decreased reaction of peripheral lymphocytes to PHA was seen in men exposed to 100-199 rad; a decreased reaction to PWM was seen in women exposed to more than 200 rad. According to the age group at examination, these decreased reactions were remarkable in men aged 60 years or younger and women aged 60 years or older. Among men less than 60-year-old exposed to 100-199 rad, PWM-induced mitosis of lymphocytes tended to be inhibited remarkably by USE. These results suggest the involvement of late A-bomb effects in mitotic regulation of T- and B-lymphocytes of aged A-bomb survivors.

Kaposi's sarcoma herpesvirus C-terminal LANA concentrates at pericentromeric and peri-telomeric regions of a subset of mitotic chromosomes

International Nuclear Information System (INIS)

Kelley-Clarke, Brenna; Ballestas, Mary E.; Komatsu, Takashi; Kaye, Kenneth M.

2007-01-01

The Kaposi's sarcoma-associated herpesvirus (KSHV) latency-associated nuclear antigen (LANA) tethers KSHV terminal repeat (TR) DNA to mitotic chromosomes to efficiently segregate episomes to progeny nuclei. LANA contains N- and C-terminal chromosome binding regions. We now show that C-terminal LANA preferentially concentrates to paired dots at pericentromeric and peri-telomeric regions of a subset of mitotic chromosomes through residues 996-1139. Deletions within C-terminal LANA abolished both self-association and chromosome binding, consistent with a requirement for self-association to bind chromosomes. A deletion abolishing TR DNA binding did not affect chromosome targeting, indicating LANA's localization is not due to binding its recognition sequence in chromosomal DNA. LANA distributed similarly on human and non-human mitotic chromosomes. These results are consistent with C-terminal LANA interacting with a cell factor that concentrates at pericentromeric and peri-telomeric regions of mitotic chromosomes

PRR11 regulates late-S to G2/M phase progression and induces premature chromatin condensation (PCC)

Energy Technology Data Exchange (ETDEWEB)

Zhang, Chundong; Zhang, Ying; Li, Yi; Zhu, Huifang; Wang, Yitao; Cai, Wei [Department of Biochemistry and Molecular Biology, Chongqing Medical University, Chongqing 400016 (China); Molecular Medicine and Cancer Research Center, Chongqing Medical University, Chongqing 400016 (China); Zhu, Jiang [Molecular Medicine and Cancer Research Center, Chongqing Medical University, Chongqing 400016 (China); Ozaki, Toshinori [Laboratory of DNA Damage Signaling, Chiba Cancer Center Research Institute, 666-2 Nitona, Chuohku, Chiba 260-8717 (Japan); Bu, Youquan, E-mail: buyqcn@aliyun.com [Department of Biochemistry and Molecular Biology, Chongqing Medical University, Chongqing 400016 (China); Molecular Medicine and Cancer Research Center, Chongqing Medical University, Chongqing 400016 (China)

2015-03-13

Recently, we have demonstrated that proline-rich protein 11 (PRR11) is a novel tumor-related gene product likely implicated in the regulation of cell cycle progression as well as lung cancer development. However, its precise role in cell cycle progression remains unclear. In the present study, we have further investigated the expression pattern and functional implication of PRR11 during cell cycle in detail in human lung carcinoma-derived H1299 cells. According to our immunofluorescence study, PRR11 was expressed largely in cytoplasm, the amount of PRR11 started to increase in the late S phase, and was retained until just before mitotic telophase. Consistent with those observations, siRNA-mediated knockdown of PRR11 caused a significant cell cycle arrest in the late S phase. Intriguingly, the treatment with dNTPs further augmented PRR11 silencing-mediated S phase arrest. Moreover, knockdown of PRR11 also resulted in a remarkable retardation of G2/M progression, and PRR11-knockdown cells subsequently underwent G2 phase cell cycle arrest accompanied by obvious mitotic defects such as multipolar spindles and multiple nuclei. In addition, forced expression of PRR11 promoted the premature Chromatin condensation (PCC), and then proliferation of PRR11-expressing cells was massively attenuated and induced apoptosis. Taken together, our current observations strongly suggest that PRR11, which is strictly regulated during cell cycle progression, plays a pivotal role in the regulation of accurate cell cycle progression through the late S phase to mitosis. - Highlights: • PRR11 started to increase in the late S phase and was retained until just before mitotic telophase. • PRR11-knockdown caused a significant cell cycle arrest in the late S phase and G2 phase. • The treatment with dNTPs further augmented PRR11 silencing-mediated S phase arrest. • PRR11-knockdown led to multipolar spindles and multiple nuclei. • Forced expression of PRR11 promoted the PCC and inhibited

PRR11 regulates late-S to G2/M phase progression and induces premature chromatin condensation (PCC)

International Nuclear Information System (INIS)

Zhang, Chundong; Zhang, Ying; Li, Yi; Zhu, Huifang; Wang, Yitao; Cai, Wei; Zhu, Jiang; Ozaki, Toshinori; Bu, Youquan

2015-01-01

Recently, we have demonstrated that proline-rich protein 11 (PRR11) is a novel tumor-related gene product likely implicated in the regulation of cell cycle progression as well as lung cancer development. However, its precise role in cell cycle progression remains unclear. In the present study, we have further investigated the expression pattern and functional implication of PRR11 during cell cycle in detail in human lung carcinoma-derived H1299 cells. According to our immunofluorescence study, PRR11 was expressed largely in cytoplasm, the amount of PRR11 started to increase in the late S phase, and was retained until just before mitotic telophase. Consistent with those observations, siRNA-mediated knockdown of PRR11 caused a significant cell cycle arrest in the late S phase. Intriguingly, the treatment with dNTPs further augmented PRR11 silencing-mediated S phase arrest. Moreover, knockdown of PRR11 also resulted in a remarkable retardation of G2/M progression, and PRR11-knockdown cells subsequently underwent G2 phase cell cycle arrest accompanied by obvious mitotic defects such as multipolar spindles and multiple nuclei. In addition, forced expression of PRR11 promoted the premature Chromatin condensation (PCC), and then proliferation of PRR11-expressing cells was massively attenuated and induced apoptosis. Taken together, our current observations strongly suggest that PRR11, which is strictly regulated during cell cycle progression, plays a pivotal role in the regulation of accurate cell cycle progression through the late S phase to mitosis. - Highlights: • PRR11 started to increase in the late S phase and was retained until just before mitotic telophase. • PRR11-knockdown caused a significant cell cycle arrest in the late S phase and G2 phase. • The treatment with dNTPs further augmented PRR11 silencing-mediated S phase arrest. • PRR11-knockdown led to multipolar spindles and multiple nuclei. • Forced expression of PRR11 promoted the PCC and inhibited

Hydrogen peroxide induced loss of heterozygosity correlates with replicative lifespan and mitotic asymmetry in Saccharomyces cerevisiae

Science.gov (United States)

Jackson, Erin D.; Parker, Meighan C.; Gupta, Nilin; Rodrigues, Jenny

2016-01-01

Cellular aging in Saccharomyces cerevisiae can lead to genomic instability and impaired mitotic asymmetry. To investigate the role of oxidative stress in cellular aging, we examined the effect of exogenous hydrogen peroxide on genomic instability and mitotic asymmetry in a collection of yeast strains with diverse backgrounds. We treated yeast cells with hydrogen peroxide and monitored the changes of viability and the frequencies of loss of heterozygosity (LOH) in response to hydrogen peroxide doses. The mid-transition points of viability and LOH were quantified using sigmoid mathematical functions. We found that the increase of hydrogen peroxide dependent genomic instability often occurs before a drop in viability. We previously observed that elevation of genomic instability generally lags behind the drop in viability during chronological aging. Hence, onset of genomic instability induced by exogenous hydrogen peroxide treatment is opposite to that induced by endogenous oxidative stress during chronological aging, with regards to the midpoint of viability. This contrast argues that the effect of endogenous oxidative stress on genome integrity is well suppressed up to the dying-off phase during chronological aging. We found that the leadoff of exogenous hydrogen peroxide induced genomic instability to viability significantly correlated with replicative lifespan (RLS), indicating that yeast cells’ ability to counter oxidative stress contributes to their replicative longevity. Surprisingly, this leadoff is positively correlated with an inverse measure of endogenous mitotic asymmetry, indicating a trade-off between mitotic asymmetry and cell’s ability to fend off hydrogen peroxide induced oxidative stress. Overall, our results demonstrate strong associations of oxidative stress to genomic instability and mitotic asymmetry at the population level of budding yeast. PMID:27833823

Early effects of boron neutron capture therapy on rat glioma models

International Nuclear Information System (INIS)

Nakagawa, N.; Akai, F.; Fukawa, N.; Taneda, M.; Ono, K.; Suzuki, M.

2006-01-01

Early effects of boron neutron capture therapy on malignant gliomas are characterized by reduction of the enhanced area regression of the peritumoral edema radiologically. The aim of this study is to investigate the early histological changes of tumors and inflammatory cells after BNCT in the rat brain. The rats were treated with BNCT using boronophenyialanine (BPA) 7 days after implantation of C6 glioma cells. The tumors were assessed their sizes and configurations with magnetic resonance imaging, then killed 4 days after BNCT. The mean tumor volumes were 39mm 3 in BNCT-treated group, and 138 mm 3 in the control group. In the histological examination, tumors of the BNCT group showed less pleomorphic appearance with atypical nuclei and mitotic figures, compared with the control group. Necrosis and edematous changes in the neuropile were negligible. There existed remnant tumors adjacent to the lateral ventricle. The reactions of the inflammatory cells were examined with ED-1 of macrophage marker. ED-1 positive cells and their processes were reduced in the marginal area of tumor in the BNCT group. BNCT reduce the tumor progression by suppression of the proliferation. Inhibition of the activated macrophages may reduce peritumoral edema in early phase. (author)

Cell-cycle variation in the induction of lethality and mitotic recombination after treatment with UV and nitrous acid in the yeast, Saccharomyces cerevisiae

International Nuclear Information System (INIS)

Davies, P.J.; Tippins, R.S.; Parry, J.M.

1978-01-01

Exponentially growing yeast cultures separated into discrete periods of the cell cycle by zonal rotor centrifugation show cyclic variation in both UV and nitrous acid induced cell lethality, mitotic gene conversion and mitotic crossing-over. Maximum cell survival after UV treatment was observed in the S and G2 phases of the cell cycle at a time when UV induction of both types of mitotic recombination was at a minumum. In contrast, cell inactivation by the chemical mutagen nitrous acid showed a single discrete period of sensitivity which occurred in S phase cells which are undergoing DNA synthesis. Mitotic gene conversion ahd mitotic crossing-over were induced by nitrous acid in cells at all stages of the cell cycle with a peak of induction of both events occurring at the time of maximum cell lethality. The lack of correlation observed between maximum cell survival and the maximum induction of mitotic intragenic recombination suggest that other DNA-repair mechanisms besides DNA-recombination repair are involved in the recovery of inactivated yeast cells during the cell cycle. (Auth.)

In vitro autoradiographic studies for determination of mitotic index and labelling index in biopsies of the human oral mucosa

International Nuclear Information System (INIS)

Etzbach, T.

1980-01-01

In order to find the most favourable method of incubation for in-vitro autoradiographies of biopsies of human oral mucosa, tissue biopsies were taken from oral mucosa transplants of 10 patients (7 females, 3 males) and either fixed or incubated at once. The author then investigated the mitotic index of the non-incubated tissue specimens, the mitotic index of the tissue specimens incubated in atmospheric conditions (A), and the mitotic index of the tissue specimens incubated under pressure (B). Simultaneously, autoradiographs of the incubated tissue specimens were prepared in order to determine their labelling indices. The mitotic indices of the non-incubated tissue specimen were found to differ significantly from those of the A-incubated tissue specimens. A similar difference was found between the mitotic indices of the A- and B-incubated tissue biopsies. Further, the labelling indices of A autoradiographs differed significantly from the labelling indices of B autoradiographs. The findings suggest that incubation with an excess oxygen pressure of 2 bar is the method of choice for in-vitro studies of human oral mucosa as the cells retain their specific activity and cell processes will continue unhindered. Further, the findings can be transferred to in-vivo conditions with a reasonable error rate. (orig./MG) [de

Immediate treatment with bicalutamide 150mg as adjuvant therapy significantly reduces the risk of PSA progression in early prostate cancer

DEFF Research Database (Denmark)

See, W; Iversen, P; Wirth, M

2003-01-01

To evaluate the effect of bicalutamide ('Casodex') 150mg (in addition to standard care), on the risk of prostate-specific antigen (PSA) progression, in patients with early prostate cancer.......To evaluate the effect of bicalutamide ('Casodex') 150mg (in addition to standard care), on the risk of prostate-specific antigen (PSA) progression, in patients with early prostate cancer....

[Effect of inhibitors serine/threonine protein kinases and protein phosphatases on mitosis progression of synchronized tobacco by-2 cells].

Science.gov (United States)

Sheremet, Ia A; Emets, A I; Azmi, A; Vissenberg, K; Verbelen, J-P; Blium, Ia B

2012-01-01

In order to investigate the role of various serine/ threonine protein kinases and protein phosphatases in the regulation of mitosis progression in plant cells the influence of cyclin-dependent (olomoucine) and Ca2+ -calmodulin-dependent (W7) protein kinases inhibitors, as well as protein kinase C inhibitors (H7 and staurosporine) and protein phosphatases inhibitor (okadaic acid) on mitosis progression in synchronized tobacco BY-2 cells has been studied. It was found that BY-2 culture treatment with inhibitors of cyclin dependent protein kinases and protein kinase C causes prophase delay, reduces the mitotic index and displaces of mitotic peak as compare with control cells. Inhibition of Ca2+ -calmodulin dependent protein kinases enhances the cell entry into prophase and delays their exit from mitosis. Meanwhile inhibition of serine/threonine protein phosphatases insignificantly enhances of synchronized BY-2 cells entering into all phases of mitosis.

AUTOMATED DETECTION OF MITOTIC FIGURES IN BREAST CANCER HISTOPATHOLOGY IMAGES USING GABOR FEATURES AND DEEP NEURAL NETWORKS

Directory of Open Access Journals (Sweden)

Maqlin Paramanandam

2016-11-01

Full Text Available The count of mitotic figures in Breast cancer histopathology slides is the most significant independent prognostic factor enabling determination of the proliferative activity of the tumor. In spite of the strict protocols followed, the mitotic counting activity suffers from subjectivity and considerable amount of observer variability despite being a laborious task. Interest in automated detection of mitotic figures has been rekindled with the advent of Whole Slide Scanners. Subsequently mitotic detection grand challenge contests have been held in recent years and several research methodologies developed by their participants. This paper proposes an efficient mitotic detection methodology for Hematoxylin and Eosin stained Breast cancer Histopathology Images using Gabor features and a Deep Belief Network- Deep Neural Network architecture (DBN-DNN. The proposed method has been evaluated on breast histopathology images from the publicly available dataset from MITOS contest held at the ICPR 2012 conference. It contains 226 mitoses annotated on 35 HPFs by several pathologists and 15 testing HPFs, yielding an F-measure of 0.74. In addition the said methodology was also tested on 3 slides from the MITOSIS- ATYPIA grand challenge held at the ICPR 2014 conference, an extension of MITOS containing 749 mitoses annotated on 1200 HPFs, by pathologists worldwide. This study has employed 3 slides (294 HPFs from the MITOS-ATYPIA training dataset in its evaluation and the results showed F-measures 0.65, 0.72and 0.74 for each slide. The proposed method is fast and computationally simple yet its accuracy and specificity is comparable to the best winning methods of the aforementioned grand challenges

Inhibition of the Ras-ERK pathway in mitotic COS7 cells is due to the inability of EGFR/Raf to transduce EGF signaling to downstream proteins.

Science.gov (United States)

Shi, Huaiping; Zhang, Tianying; Yi, Yongqing; Ma, Yue

2016-06-01

Although previous studies have shown that Ras-ERK signaling in mitosis is closed due to the inhibition of signal transduction, the events involved in the molecular mechanisms are still unclear. In the present study, we investigated the Ras-ERK signaling pathway in mitotic COS7 cells. The results demonstrated that treatment with epidermal growth factor (EGF) failed to increase the endocytosis of EGF-EGFR (EGF receptor) complexes in mitotic COS7 cells, although a large amount of endosomes were found in asynchronous COS7 cells. Clathrin expression levels in mitotic COS7 cells were inhibited whereas caveolin expression levels in mitotic COS7 cells were almost unaffected. Y1068 and Y1086 residues of EGFR in the mitotic COS7 cells were activated. However, Grb2 and Shc in the mitotic COS7 cells did not bind to activated EGFR. Ras activity was inhibited in the mitotic COS7 cells whereas its downstream protein, Raf, was obviously phosphorylated by EGF in mitosis. Treatment with phorbol 12-myristate 13-acetate (PMA) also increased the phosphorylation levels of Raf in the mitotic COS7 cells. Nevertheless, Raf phosphorylation in mitosis was significantly inhibited by AG1478. Lastly, activation of EGF-mediated MEK and ERK in the mitotic COS7 cells was obviously inhibited. In summary, our results suggest that the Ras-ERK pathway is inhibited in mitotic COS7 cells which may be the dual result of the difficulty in the transduction of EGF signaling by EGFR or Raf to downstream proteins.

Evaluation of F8-TNF-α in Models of Early and Progressive Metastatic Osteosarcoma

Directory of Open Access Journals (Sweden)

Bernhard Robl

2017-06-01

Full Text Available The targeted delivery of tumor necrosis factor-α (TNF-α with antibodies specific to splice isoforms of fibronectin [e.g., F8-TNF, specific to the extra-domain A (EDA domain of fibronectin] has already shown efficacy against experimental sarcomas but has not yet been investigated in orthotopic sarcomas. Here, we investigated F8-TNF in a syngeneic K7 M2–derived orthotopic model of osteosarcoma as a treatment against pulmonary metastases, the most frequent cause of osteosarcoma-related death. Immunofluorescence on human osteosarcoma tissue confirmed the presence of EDA in primary tumors (PTs as well as metastases. In mice, the efficacy of F8-TNF against PTs and early pulmonary metastases was evaluated. Intratibial PT growth was not affected by F8-TNF, yet early micrometastases were reduced possibly due to an F8-TNF–dependent attraction of pulmonary CD4+, CD8+, and natural killer cells. Furthermore, immunofluorescence revealed stronger expression of EDA in early pulmonary metastases compared with PT tissue. To study progressing pulmonary metastases, a hind limb amputation model was established, and the efficacy of F8-TNF, alone or combined with doxorubicin, was investigated. Despite the presence of EDA in metastases, no inhibition of progressive metastatic growth was detected. No significant differences in numbers of CD4+ or CD8+ cells or F4/80+ and Ly6G+ myeloid-derived cells were observed, although a strong association between metastatic growth and presence of pulmonary Ly6G+ myeloid-derived cells was detected. In summary, these findings demonstrate the potential of F8-TNF in activating the immune system and reducing early metastatic growth yet suggest a lack of efficacy of F8-TNF alone or combined with doxorubicin against progressing osteosarcoma metastases.

Evaluation of F8-TNF-α in Models of Early and Progressive Metastatic Osteosarcoma.

Science.gov (United States)

Robl, Bernhard; Botter, Sander Martijn; Boro, Aleksandar; Meier, Daniela; Neri, Dario; Fuchs, Bruno

2017-06-01

The targeted delivery of tumor necrosis factor-α (TNF-α) with antibodies specific to splice isoforms of fibronectin [e.g., F8-TNF, specific to the extra-domain A (EDA) domain of fibronectin] has already shown efficacy against experimental sarcomas but has not yet been investigated in orthotopic sarcomas. Here, we investigated F8-TNF in a syngeneic K7 M2-derived orthotopic model of osteosarcoma as a treatment against pulmonary metastases, the most frequent cause of osteosarcoma-related death. Immunofluorescence on human osteosarcoma tissue confirmed the presence of EDA in primary tumors (PTs) as well as metastases. In mice, the efficacy of F8-TNF against PTs and early pulmonary metastases was evaluated. Intratibial PT growth was not affected by F8-TNF, yet early micrometastases were reduced possibly due to an F8-TNF-dependent attraction of pulmonary CD4 + , CD8 + , and natural killer cells. Furthermore, immunofluorescence revealed stronger expression of EDA in early pulmonary metastases compared with PT tissue. To study progressing pulmonary metastases, a hind limb amputation model was established, and the efficacy of F8-TNF, alone or combined with doxorubicin, was investigated. Despite the presence of EDA in metastases, no inhibition of progressive metastatic growth was detected. No significant differences in numbers of CD4 + or CD8 + cells or F4/80 + and Ly6G + myeloid-derived cells were observed, although a strong association between metastatic growth and presence of pulmonary Ly6G + myeloid-derived cells was detected. In summary, these findings demonstrate the potential of F8-TNF in activating the immune system and reducing early metastatic growth yet suggest a lack of efficacy of F8-TNF alone or combined with doxorubicin against progressing osteosarcoma metastases. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

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

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Hitomi, Toshiaki [Department of Health and Environmental Sciences, Graduate School of Medicine, Kyoto University, Kyoto (Japan); Habu, Toshiyuki [Radiation Biology Center, Kyoto University, Kyoto (Japan); Kobayashi, Hatasu; Okuda, Hiroko; Harada, Kouji H. [Department of Health and Environmental Sciences, Graduate School of Medicine, Kyoto University, Kyoto (Japan); Osafune, Kenji [Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto (Japan); Taura, Daisuke; Sone, Masakatsu [Department of Medicine and Clinical Science, Graduate School of Medicine, Kyoto University, Kyoto (Japan); Asaka, Isao; Ameku, Tomonaga; Watanabe, Akira; Kasahara, Tomoko; Sudo, Tomomi; Shiota, Fumihiko [Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto (Japan); Hashikata, Hirokuni; Takagi, Yasushi [Department of Neurosurgery, Graduate School of Medicine, Kyoto University, Kyoto (Japan); Morito, Daisuke [Faculty of Life Sciences, Kyoto Sangyo University, Kyoto (Japan); Miyamoto, Susumu [Department of Neurosurgery, Graduate School of Medicine, Kyoto University, Kyoto (Japan); Nakao, Kazuwa [Department of Medicine and Clinical Science, Graduate School of Medicine, Kyoto University, Kyoto (Japan); Koizumi, Akio, E-mail: koizumi.akio.5v@kyoto-u.ac.jp [Department of Health and Environmental Sciences, Graduate School of Medicine, Kyoto University, Kyoto (Japan)

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.

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

International Nuclear Information System (INIS)

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

2013-01-01

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

Kalanchoe tubiflora extract inhibits cell proliferation by affecting the mitotic apparatus

Directory of Open Access Journals (Sweden)

Hsieh Yi-Jen

2012-09-01

Full Text Available Abstract Background Kalanchoe tubiflora (KT is a succulent plant native to Madagascar, and is commonly used as a medicinal agent in Southern Brazil. The underlying mechanisms of tumor suppression are largely unexplored. Methods Cell viability and wound-healing were analyzed by MTT assay and scratch assay respectively. Cell cycle profiles were analyzed by FACS. Mitotic defects were analyzed by indirect immunofluoresence images. Results An n-Butanol-soluble fraction of KT (KT-NB was able to inhibit cell proliferation. After a 48 h treatment with 6.75 μg/ml of KT, the cell viability was less than 50% of controls, and was further reduced to less than 10% at higher concentrations. KT-NB also induced an accumulation of cells in the G2/M phase of the cell cycle as well as an increased level of cells in the subG1 phase. Instead of disrupting the microtubule network of interphase cells, KT-NB reduced cell viability by inducing multipolar spindles and defects in chromosome alignment. KT-NB inhibits cell proliferation and reduces cell viability by two mechanisms that are exclusively involved with cell division: first by inducing multipolarity; second by disrupting chromosome alignment during metaphase. Conclusion KT-NB reduced cell viability by exclusively affecting formation of the proper structure of the mitotic apparatus. This is the main idea of the new generation of anti-mitotic agents. All together, KT-NB has sufficient potential to warrant further investigation as a potential new anticancer agent candidate.

Incorporation of thymidine into onion root meristematic cell nuclei in presence of hydroxyurea and its role in recovery of mitotic activity

OpenAIRE

H. Habdas

2015-01-01

Hydroxyurea treatment of onion roots induced mitotic block which was released by transfer of bulbs to water, and also to some extent by addition of cold or 3H-thymidine to hydroxyurea solutions. In presence of hydroxyurea there was noted very intense incorporation of 3H-thymidine into cell nuclei, giving labelling index of 40-70%. However, all the mitotic figures appearing in presence of hydroxyurea and 3H-thymidine were unlabelled. On the other hand, labelled mitotic figures were obtained wh...

SAP-like domain in nucleolar spindle associated protein mediates mitotic chromosome loading as well as interphase chromatin interaction

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Verbakel, Werner, E-mail: werner.verbakel@chem.kuleuven.be [Laboratory of Biomolecular Dynamics, Katholieke Universiteit Leuven, Celestijnenlaan 200G, Bus 2403, 3001 Heverlee (Belgium); Carmeliet, Geert, E-mail: geert.carmeliet@med.kuleuven.be [Laboratory of Experimental Medicine and Endocrinology, Katholieke Universiteit Leuven, Herestraat 49, Bus 902, 3000 Leuven (Belgium); Engelborghs, Yves, E-mail: yves.engelborghs@fys.kuleuven.be [Laboratory of Biomolecular Dynamics, Katholieke Universiteit Leuven, Celestijnenlaan 200G, Bus 2403, 3001 Heverlee (Belgium)

2011-08-12

Highlights: {yields} The SAP-like domain in NuSAP is a functional DNA-binding domain with preference for dsDNA. {yields} This SAP-like domain is essential for chromosome loading during early mitosis. {yields} NuSAP is highly dynamic on mitotic chromatin, as evident from photobleaching experiments. {yields} The SAP-like domain also mediates NuSAP-chromatin interaction in interphase nucleoplasm. -- Abstract: Nucleolar spindle associated protein (NuSAP) is a microtubule-stabilizing protein that localizes to chromosome arms and chromosome-proximal microtubules during mitosis and to the nucleus, with enrichment in the nucleoli, during interphase. The critical function of NuSAP is underscored by the finding that its depletion in HeLa cells results in various mitotic defects. Moreover, NuSAP is found overexpressed in multiple cancers and its expression levels often correlate with the aggressiveness of cancer. Due to its localization on chromosome arms and combination of microtubule-stabilizing and DNA-binding properties, NuSAP takes a special place within the extensive group of spindle assembly factors. In this study, we identify a SAP-like domain that shows DNA binding in vitro with a preference for dsDNA. Deletion of the SAP-like domain abolishes chromosome arm binding of NuSAP during mitosis, but is not sufficient to abrogate its chromosome-proximal localization after anaphase onset. Fluorescence recovery after photobleaching experiments revealed the highly dynamic nature of this NuSAP-chromatin interaction during mitosis. In interphase cells, NuSAP also interacts with chromatin through its SAP-like domain, as evident from its enrichment on dense chromatin regions and intranuclear mobility, measured by fluorescence correlation spectroscopy. The obtained results are in agreement with a model where NuSAP dynamically stabilizes newly formed microtubules on mitotic chromosomes to enhance chromosome positioning without immobilizing these microtubules. Interphase Nu

SAP-like domain in nucleolar spindle associated protein mediates mitotic chromosome loading as well as interphase chromatin interaction

International Nuclear Information System (INIS)

Verbakel, Werner; Carmeliet, Geert; Engelborghs, Yves

2011-01-01

Highlights: → The SAP-like domain in NuSAP is a functional DNA-binding domain with preference for dsDNA. → This SAP-like domain is essential for chromosome loading during early mitosis. → NuSAP is highly dynamic on mitotic chromatin, as evident from photobleaching experiments. → The SAP-like domain also mediates NuSAP-chromatin interaction in interphase nucleoplasm. -- Abstract: Nucleolar spindle associated protein (NuSAP) is a microtubule-stabilizing protein that localizes to chromosome arms and chromosome-proximal microtubules during mitosis and to the nucleus, with enrichment in the nucleoli, during interphase. The critical function of NuSAP is underscored by the finding that its depletion in HeLa cells results in various mitotic defects. Moreover, NuSAP is found overexpressed in multiple cancers and its expression levels often correlate with the aggressiveness of cancer. Due to its localization on chromosome arms and combination of microtubule-stabilizing and DNA-binding properties, NuSAP takes a special place within the extensive group of spindle assembly factors. In this study, we identify a SAP-like domain that shows DNA binding in vitro with a preference for dsDNA. Deletion of the SAP-like domain abolishes chromosome arm binding of NuSAP during mitosis, but is not sufficient to abrogate its chromosome-proximal localization after anaphase onset. Fluorescence recovery after photobleaching experiments revealed the highly dynamic nature of this NuSAP-chromatin interaction during mitosis. In interphase cells, NuSAP also interacts with chromatin through its SAP-like domain, as evident from its enrichment on dense chromatin regions and intranuclear mobility, measured by fluorescence correlation spectroscopy. The obtained results are in agreement with a model where NuSAP dynamically stabilizes newly formed microtubules on mitotic chromosomes to enhance chromosome positioning without immobilizing these microtubules. Interphase NuSAP-chromatin interaction

Mitotic catastrophe occurs in the absence of apoptosis in p53-null cells with a defective G1 checkpoint.

Directory of Open Access Journals (Sweden)

Michalis Fragkos

Full Text Available Cell death occurring during mitosis, or mitotic catastrophe, often takes place in conjunction with apoptosis, but the conditions in which mitotic catastrophe may exhibit features of programmed cell death are still unclear. In the work presented here, we studied mitotic cell death by making use of a UV-inactivated parvovirus (adeno-associated virus; AAV that has been shown to induce a DNA damage response and subsequent death of p53-defective cells in mitosis, without affecting the integrity of the host genome. Osteosarcoma cells (U2OSp53DD that are deficient in p53 and lack the G1 cell cycle checkpoint respond to AAV infection through a transient G2 arrest. We found that the infected U2OSp53DD cells died through mitotic catastrophe with no signs of chromosome condensation or DNA fragmentation. Moreover, cell death was independent of caspases, apoptosis-inducing factor (AIF, autophagy and necroptosis. These findings were confirmed by time-lapse microscopy of cellular morphology following AAV infection. The assays used readily revealed apoptosis in other cell types when it was indeed occurring. Taken together the results indicate that in the absence of the G1 checkpoint, mitotic catastrophe occurs in these p53-null cells predominantly as a result of mechanical disruption induced by centrosome overduplication, and not as a consequence of a suicide signal.

Feasibility of Early-Initiated Progressive Resistance Training after Total Hip Replacement

DEFF Research Database (Denmark)

Mikkelsen, Lone Ramer; Mechlenburg, Inger; Petersen, Annemette Krintel

during the exercises were measured at each training session. Isometric muscle strength was measured before and 4 weeks after the THR. Findings / Results: Pain during exercises and resting pain before and after each training session was unchanged or decreased during the 4 weeks of training. Averaged...... across exercises pain during training decreased from 3.6 (sd: 2.8) at the first session to 1.52 (sd: 1.8) VAS-mm at the last session, ptraining load increased progressively for all 4 exercises during the 4 weeks of training. For example: 2nd, 5th and 8th training session. Hip......Background: Muscle atrophy, reduced hip muscle strength and function are documented within the first weeks after Total Hip Replacement (THR). Purpose / Aim of Study: The purpose of this study was to evaluate the feasibility of early-initiated progressive resistance training (PRT) after THR...

Analysis of the Ceratitis capitata y chromosome using in situ hybridization to mitotic chromosomes

International Nuclear Information System (INIS)

Willhoeft, U.; Franz, G.

1998-01-01

In Ceratitis capitata the Y chromosome is responsible for sex-determination. We used fluorescence in situ hybridization (FISH) for cytogenetic analysis of mitotic chromosomes. FISH with the wild-type strain EgyptII and two repetitive DNA probes enabled us to differentiate between the short and the long arm of the Y chromosome and gives a much better resolution than C-banding of mitotic chromosomes. We identified the Y-chromosomal breakpoints in Y-autosome translocations using FISH. Even more complex rearrangements i.e. deletions and insertions in some translocation strains were detected by this method. A strategy for mapping the primary sex determination factor in Ceratitis capitata by FISH is presented. (author)

Action of plasma and liver extract from adult mice on the mitotic activity of young mouse liver.

Science.gov (United States)

García, A L; Inda, A M; Echave Llanos, J M

1991-06-01

Inbred C3HS male mice, standardized for periodicity analysis were used. A hundred and seventy 25 +/- 2 days old mice were injected at 16:00 hs with saline, plasma or liver extract from 27 mice 90 days old. Controls were made at 08/16, 12/20, 16/24, 08/40, 12/44, 16/48, 08/64, 12/68 and 16/72 (time of day/time post-injection). The mitotic activity of the hepatocytes and litoral cells were determined. The injection of small doses of extract and plasma inhibits the mitotic activity of hepatocytes during the first and second following days. A compensatory wave appears in the third day. The extract inhibits the mitotic activity of litoral cells in the first day of control only, whereas the plasma inhibits this variable in the second and third day.

Variation in sensitivity to #betta#-ray-induced chromosomal aberrations during the mitotic cycle of the sea urchin egg

International Nuclear Information System (INIS)

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

1982-01-01

Sea urchin eggs were irradiated with 137 Cs #betta# 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

Radiation induced mitotic delay and stimulation of growth

International Nuclear Information System (INIS)

Feldmann, A.

1974-01-01

The mechanisms responsible for the radiation induced mitotic delay and stimulation of growth are discussed in connection with the results of studies in Lemna minor and Lepidium sativum. The action of temperature seems to be of major importance. As many authors suggest that various chemical agents and slight intoxications also affect mitosis in a way similar to that induced by ionizing radiation, the radiation induced stimulation has lost its specific character and approaches might be found for further investigations of this phenomenon. (MG) [de

Progress in Early Childhood Caries and Opportunities in Research, Policy, and Clinical Management

DEFF Research Database (Denmark)

Garcia, Raul; Borrelli, Belinda; Dhar, Vineet

2015-01-01

The 2014 Early Childhood Caries Conference encompassed evidence-based reviews on the state of the science regarding early childhood carries (ECC) epidemiology, etiology, prevention, and disease management. The purpose of this paper was to discuss the work presented at the conference and identify...... means to prevent and manage ECC. Analyses of studies indicate that some approaches, such as chlorhexidine, iodine, and remineralizing agents, have not shown consistent findings in preventing ECC. However, evidence exists to yield recommendations in some areas. There are useful risk assessment indicators...... opportunities in research, policy, and clinical management that may improve early childhood caries outcomes and lower costs of care. While great progress has been made since the 1997 ECC Conference, there remains a paucity of high-quality evidence from randomized controlled trials on what are the most effective...

Comparison of staining of mitotic figures by haematoxylin and eosin-and crystal violet stains, in oral epithelial dysplasia and squamous cell carcinoma

Directory of Open Access Journals (Sweden)

Ankle Madhuri

2007-01-01

Full Text Available Mitosis of cells gives rise to tissue integrity. Defects during mitosis bring about abnormalities. Excessive proliferation of cells due to increased mitosis is one such outcome, which is the hallmark in precancer and cancer. The localization of proliferating cells or their precursors may not be obvious and easy. Establishing an easy way to distinguish these mitotic cells will help in grading and understanding their biological potential. Although immunohistochemistry is an advanced method in use, the cost and time factor makes it less feasible for many laboratories. Selective histochemical stains like toluidine blue, giemsa and crystal violet have been used in tissues including the developing brain, neural tissue and skin. Aim of the study: 1To compare the staining of mitotic cells in haematoxylin and eosin with that in crystal violet. 2To compare the number of mitotic figures present in normal oral mucosa, epithelial dysplasia and oral squamous cell carcinoma in crystal violet-stained sections with that in H and E-stained sections. Materials and Methods: Ten tissues of normal oral mucosa and 15 tissues each of oral epithelial dysplasia seen in tobacco-associated leukoplakia and squamous cell carcinoma were studied to evaluate the selectivity of 1% crystal violet for mitotic figures. The staining was compared with standard H and E staining. Statistical analysis was done using Man-Whitney U test. Results: A statistically significant increase in the mean mitotic count was observed in crystal violet-stained sections of epithelial dysplasia as compared to the H and E-stained sections ( p = 0.0327. A similar increase in the mitotic counts was noted in crystal violet-stained sections of oral squamous cell carcinoma as compared to the H and E-stained sections.( p = 0.0443. No significant difference was found in the mitotic counts determined in dysplasia or carcinoma by either the crystal violet ( p = 0.4429 or the H and E-staining techniques ( p = 0

Live-Cell Imaging Visualizes Frequent Mitotic Skipping During Senescence-Like Growth Arrest in Mammary Carcinoma Cells Exposed to Ionizing Radiation

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Suzuki, Masatoshi, E-mail: msuzuki@nagasaki-u.ac.jp [Department of Radiation Medical Sciences, Atomic Bomb Disease Institute, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki (Japan); Yamauchi, Motohiro; Oka, Yasuyoshi; Suzuki, Keiji; Yamashita, Shunichi [Department of Radiation Medical Sciences, Atomic Bomb Disease Institute, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki (Japan)

2012-06-01

Purpose: Senescence-like growth arrest in human solid carcinomas is now recognized as the major outcome of radiotherapy. This study was designed to analyze cell cycle during the process of senescence-like growth arrest in mammary carcinoma cells exposed to X-rays. Methods and Materials: Fluorescent ubiquitination-based cell cycle indicators were introduced into the human mammary carcinoma cell line MCF-7. Cell cycle was sequentially monitored by live-cell imaging for up to 5 days after exposure to 10 Gy of X-rays. Results: Live-cell imaging revealed that cell cycle transition from G2 to G1 phase without mitosis, so-called mitotic skipping, was observed in 17.1% and 69.8% of G1- and G2-irradiated cells, respectively. Entry to G1 phase was confirmed by the nuclear accumulation of mKO{sub 2}-hCdt1 as well as cyclin E, which was inversely correlated to the accumulation of G2-specific markers such as mAG-hGeminin and CENP-F. More than 90% of cells skipping mitosis were persistently arrested in G1 phase and showed positive staining for the senescent biochemical marker, which is senescence-associated ss-galactosidase, indicating induction of senescence-like growth arrest accompanied by mitotic skipping. While G2 irradiation with higher doses of X-rays induced mitotic skipping in approximately 80% of cells, transduction of short hairpin RNA (shRNA) for p53 significantly suppressed mitotic skipping, suggesting that ionizing radiation-induced mitotic skipping is associated with p53 function. Conclusions: The present study found the pathway of senescence-like growth arrest in G1 phase without mitotic entry following G2-irradiation.

Live-Cell Imaging Visualizes Frequent Mitotic Skipping During Senescence-Like Growth Arrest in Mammary Carcinoma Cells Exposed to Ionizing Radiation

International Nuclear Information System (INIS)

Suzuki, Masatoshi; Yamauchi, Motohiro; Oka, Yasuyoshi; Suzuki, Keiji; Yamashita, Shunichi

2012-01-01

Purpose: Senescence-like growth arrest in human solid carcinomas is now recognized as the major outcome of radiotherapy. This study was designed to analyze cell cycle during the process of senescence-like growth arrest in mammary carcinoma cells exposed to X-rays. Methods and Materials: Fluorescent ubiquitination-based cell cycle indicators were introduced into the human mammary carcinoma cell line MCF-7. Cell cycle was sequentially monitored by live-cell imaging for up to 5 days after exposure to 10 Gy of X-rays. Results: Live-cell imaging revealed that cell cycle transition from G2 to G1 phase without mitosis, so-called mitotic skipping, was observed in 17.1% and 69.8% of G1- and G2-irradiated cells, respectively. Entry to G1 phase was confirmed by the nuclear accumulation of mKO 2 -hCdt1 as well as cyclin E, which was inversely correlated to the accumulation of G2-specific markers such as mAG-hGeminin and CENP-F. More than 90% of cells skipping mitosis were persistently arrested in G1 phase and showed positive staining for the senescent biochemical marker, which is senescence-associated ß-galactosidase, indicating induction of senescence-like growth arrest accompanied by mitotic skipping. While G2 irradiation with higher doses of X-rays induced mitotic skipping in approximately 80% of cells, transduction of short hairpin RNA (shRNA) for p53 significantly suppressed mitotic skipping, suggesting that ionizing radiation-induced mitotic skipping is associated with p53 function. Conclusions: The present study found the pathway of senescence-like growth arrest in G1 phase without mitotic entry following G2-irradiation.

Effects of deep brain stimulation on rest tremor progression in early stage Parkinson disease.

Science.gov (United States)

Hacker, Mallory L; DeLong, Mahlon R; Turchan, Maxim; Heusinkveld, Lauren E; Ostrem, Jill L; Molinari, Anna L; Currie, Amanda D; Konrad, Peter E; Davis, Thomas L; Phibbs, Fenna T; Hedera, Peter; Cannard, Kevin R; Drye, Lea T; Sternberg, Alice L; Shade, David M; Tonascia, James; Charles, David

2018-06-29

To evaluate whether the progression of individual motor features was influenced by early deep brain stimulation (DBS), a post hoc analysis of Unified Parkinson's Disease Rating Scale-III (UPDRS-III) score (after a 7-day washout) was conducted from the 2-year DBS in early Parkinson disease (PD) pilot trial dataset. The prospective pilot trial enrolled patients with PD aged 50-75 years, treated with PD medications for 6 months-4 years, and no history of dyskinesia or other motor fluctuations, who were randomized to receive optimal drug therapy (ODT) or DBS plus ODT (DBS + ODT). At baseline and 6, 12, 18, and 24 months, all patients stopped all PD therapy for 1 week (medication and stimulation, if applicable). UPDRS-III "off" item scores were compared between the ODT and DBS + ODT groups (n = 28); items with significant between-group differences were analyzed further. UPDRS-III "off" rest tremor score change from baseline to 24 months was worse in patients receiving ODT vs DBS + ODT ( p = 0.002). Rest tremor slopes from baseline to 24 months favored DBS + ODT both "off" and "on" therapy ( p will be tested in the Food and Drug Administration-approved, phase III, pivotal, multicenter clinical trial evaluating DBS in early PD. This study provides Class II evidence that for patients with early PD, DBS may slow the progression of rest tremor. © 2018 American Academy of Neurology.

JAK2V617F mutation in chronic myeloid leukemia predicts early disease progression

International Nuclear Information System (INIS)

Pahore, Z.A.A.; Shamsi, T.S.; Taj, M.; Farzana, T.; Ansari, S.H.; Nadeem, M.; Ahmad, M.; Naz, A.

2011-01-01

Objective: To determine the association of JAK2V617F mutation along with BCR-ABL translocation or Philadelphia chromosome in chronic myeloid leukemia with early disease progression to advanced stages (accelerated phase or blast crisis) and poor outcome. Study Design: Case series. Place and Duration of Study: National Institute of Blood Diseases and Bone Marrow Transplantation, Karachi, from February 2008 to August 2009. Methodology: All the newly diagnosed cases of BCR-ABL or Philadelphia positive CML were tested for JAK2V617F mutation by Nested PCR. Demographic data, spleen size, hemoglobin levels, white blood cell and platelet counts were recorded. Independent sample t-test was used for age, haemoglobin level and spleen size. Fisher's exact test was applied to compare disease progression in JAK2V617F mutation positive and negative cases. Results: Out of 45 newly diagnosed cases of CML, 40 were in chronic phase, 01 in accelerated phase and 04 in blast crisis. JAK2V617F mutation was detected in 12 (26.7%) patients; 09 (22.5%) in chronic phase, none in accelerated phase and 03 (75%) in blast crisis. During a mean follow-up of 8 months, 03 patients in chronic phase transformed in blast crisis and 02 into accelerated phase. Overall 08 out of 11 (73%) JAK2V617F positive patients either had advanced disease or showed disease progression. Only 2 of 20 (10%) available patients, negative for the mutation, showed disease progression by transforming into blast crisis (p < 0.001). No statistically significant difference was seen in the age, spleen size, haemoglobin levels, white blood cells and platelets counts in JAK2V617F positive patients. Conclusion: JAK2V617F mutation was detected in 26.7% cases of chronic myeloid leukemia. A significant proportion of them showed early disease progression. (author)

Parameters of mitotic recombination in minute mutants of Drosophila melanogaster

International Nuclear Information System (INIS)

Ferrus, A.

1975-01-01

A sample of 16 Minutes, representing 12 loci distributed over all the chromosome arms and including 3 pairs of alleles and 4 deficiencies, has been studied with respect to several developmental and recombinational parameters. Cell marker mutants located in most of the chromosome arms were used to assess (1) spontaneous and x-ray-induced mitotic recombination frequencies of each Minute, and (2) clone sizes of the different cell marker clones. These parameters were analyzed both in the wing disc and in the abdominal histoblasts. Whereas spontaneous frequencies are not affected by the presence of the Minutes studied, the different Minutes characteristically increase the frequency of recombination clones arising after x irradiation. The recombinant clones which are M + /M + are significantly larger than clones in the same fly which retain the M + /M condition. This is particularly striking in clones in the wing disc, slightly so in clones in the tergites. The occurrence of mitotic recombination in the fourth chromosome is reported for the first time. Chaeta length and developmental delay correlates with the recombinational parameters in different ways. Possible causal interrelationships of the different traits of the Minute syndrome are discussed. (U.S.)

Pregnancy and HIV Disease Progression in an Early Infection Cohort from Five African Countries.

Science.gov (United States)

Wall, Kristin M; Rida, Wasima; Haddad, Lisa B; Kamali, Anatoli; Karita, Etienne; Lakhi, Shabir; Kilembe, William; Allen, Susan; Inambao, Mubiana; Yang, Annie H; Latka, Mary H; Anzala, Omu; Sanders, Eduard J; Bekker, Linda-Gail; Edward, Vinodh A; Price, Matt A

2017-03-01

Understanding associations between pregnancy and HIV disease progression is critical to provide appropriate counseling and care to HIV-positive women. From 2006 to 2011, women less than age 40 with incident HIV infection were enrolled in an early HIV infection cohort in Kenya, Rwanda, South Africa, Uganda, and Zambia. Time-dependent Cox models evaluated associations between pregnancy and HIV disease progression. Clinical progression was defined as a single CD4 measurement pregnancy. Among 222 women, 63 experienced clinical progression during 783.5 person-years at risk (8.0/100). Among 205 women, 87 experienced immunologic progression during 680.1 person-years at risk (12.8/100). The association between pregnancy and clinical progression was adjusted hazard ratio [aHR] = 0.7; 95% confidence interval (CI): 0.2, 1.8. The association between pregnancy and immunologic progression was aHR = 1.7; 95% CI: 0.9, 3.3. Models controlled for age; human leukocyte antigen alleles A*03:01, B*45, B*57; CD4 set point; and HIV-1 subtype. CD4 measurements before versus after pregnancies were not different. In this cohort, pregnancy was not associated with increased clinical or immunologic HIV progression. Similarly, we did not observe meaningful deleterious associations of pregnancy with CD4s. Our findings suggest that HIV-positive women may become pregnant without harmful health effects occurring during the pregnancy. Evaluation of longer-term impact of pregnancy on progression is warranted.

UV-induced mitotic recombination and its dependence on photoreactivation and liquid holding in the rad6-1 mutant of Saccharomyces cerevisiae

International Nuclear Information System (INIS)

Haladus, E.; Zuk, J.

1980-01-01

Spontaneous and UV-induced mitotic recombination was compared in diploids homozygous for rad6-1 mutation and in the wild-type strain carrying heterozygous markers for detecting gene conversion (hom 2-1, hom 2-2) and crossing over (ade 1, ade 2). Diploids homozygous for rad6-1 mutation were characterised by an elevated level of spontaneous and UV-induced mitotic recombination, particularly the intergenic events. Exposure of UV-irradiated strains to visible light resulted in an increased survival and decreased level of mitotic recombination. Liquid holding (LH) differentially affected frequency of mitotic intergenic and intragenic recombination in mutant and wild-type strains, being without any significant effect on cell survival. In a mutant strain intragenic recombination is significantly increased, intergenic only slightly. In the wild-type strain intragenic recombination is slightly decreased but intergenic is not changed by LH. Visible light applied after LH had no effect on survival and mitotic recombination in the wild type, while in the mutant strain photoreactivability of survival was fully preserved and accompanied by a decrease in the frequency of intragenic and intergenic recombination. The results suggest that metabolic pathways responsible for restoring cell survival are independent of or only partly overlapping with those concerning recombination events. (orig.) [de

Early depletion of proliferating B cells of germinal center in rapidly progressive simian immunodeficiency virus infection

International Nuclear Information System (INIS)

Zhang Zhiqiang; Casimiro, Danilo R.; Schleif, William A.; Chen, Minchun; Citron, Michael; Davies, Mary-Ellen; Burns, Janine; Liang, Xiaoping; Fu, Tong-Ming; Handt, Larry; Emini, Emilio A.; Shiver, John W.

2007-01-01

Lack of virus specific antibody response is commonly observed in both HIV-1-infected humans and SIV-infected monkeys with rapid disease progression. However, the mechanisms underlying this important observation still remain unclear. In a titration study of a SIVmac239 viral stock, three out of six animals with viral inoculation rapidly progressed to AIDS within 5 months. Unexpectedly, there was no obvious depletion of CD4 + T cells in both peripheral and lymph node (LN) compartments in these animals. Instead, progressive depletion of proliferating B cells and disruption of the follicular dendritic cell (FDC) network in germinal centers (GC) was evident in the samples collected at as early as 20 days after viral challenge. This coincided with undetectable, or weak and transient, virus-specific antibody responses over the course of infection. In situ hybridization of SIV RNA in the LN samples revealed a high frequency of SIV productively infected cells and large amounts of accumulated viral RNA in the GCs in these animals. Early severe depletion of GC proliferating B cells and disruption of the FDC network may thus result in an inability to mount a virus-specific antibody response in rapid progressors, which has been shown to contribute to accelerated disease progression of SIV infection

Rac1-dependent recruitment of PAK2 to G 2 phase centrosomes and their roles in the regulation of mitotic entry

DEFF Research Database (Denmark)

May, Martin; Schelle, Ilona; Brakebusch, Cord Herbert

2014-01-01

-GTPases Rac/Cdc42. In this study, Rac1 (but not RhoA or Cdc42) is presented to associate with the centrosomes from early G 2 phase until prometaphase in a cell cycle-dependent fashion, as evidenced by western blot analysis of prepared centrosomes and by immunolabeling. PAK associates with the G 2/M......-phase centrosomes in a Rac1-dependent fashion. Furthermore, specific inhibition of Rac1 by C. difficile toxinB-catalyzed glucosylation or by knockout results in inhibited activation of PAK1/2, Aurora A, and the CyclinB/Cdk1 complex in late G 2 phase/prophase and delayed mitotic entry. Inhibition of PAK activation...

Incorporation of thymidine into onion root meristematic cell nuclei in presence of hydroxyurea and its role in recovery of mitotic activity

International Nuclear Information System (INIS)

Habdas, H.

1977-01-01

Hydroxyurea treatment of onion roots induced mitotic block which was released by transfer of bulbs to water, and also to some extent by addition of cold or 3 H-thymidine to hydroxyurea solutions. In presence of hydroxyurea there was noted very intense incorporation of 3 H-thymidine into cell nuclei, giving labelling index of 40-70%. However, all the mitotic figures appearing in presence of hydroxyurea and 3 H-thymidine were unlabelled. On the other hand, labelled mitotic figures were obtained when roots incubated with 3 H-thymidine in presence of hydroxyurea had been transferred to water. Incorporation of 3 H-uridine was unaffected by hydroxyurea. The results show that hydroxyurea arrests onion root meristematic cells, either in the S phase and the G 2 phase. Enhanced incorporation of 3 H-thymidine in the presence of hydroxyurea, and release by added thymidine of the mitotic block indicate that hydroxyurea induces in onion root meristematic cells a particular shortage of thymidylate. (author)

A central region in the minor capsid protein of papillomaviruses facilitates viral genome tethering and membrane penetration for mitotic nuclear entry.

Directory of Open Access Journals (Sweden)

Inci Aydin

2017-05-01

Full Text Available Incoming papillomaviruses (PVs depend on mitotic nuclear envelope breakdown to gain initial access to the nucleus for viral transcription and replication. In our previous work, we hypothesized that the minor capsid protein L2 of PVs tethers the incoming vDNA to mitotic chromosomes to direct them into the nascent nuclei. To re-evaluate how dynamic L2 recruitment to cellular chromosomes occurs specifically during prometaphase, we developed a quantitative, microscopy-based assay for measuring the degree of chromosome recruitment of L2-EGFP. Analyzing various HPV16 L2 truncation-mutants revealed a central chromosome-binding region (CBR of 147 amino acids that confers binding to mitotic chromosomes. Specific mutations of conserved motifs (IVAL286AAAA, RR302/5AA, and RTR313EEE within the CBR interfered with chromosomal binding. Moreover, assembly-competent HPV16 containing the chromosome-binding deficient L2(RTR313EEE or L2(IVAL286AAAA were inhibited for infection despite their ability to be transported to intracellular compartments. Since vDNA and L2 were not associated with mitotic chromosomes either, the infectivity was likely impaired by a defect in tethering of the vDNA to mitotic chromosomes. However, L2 mutations that abrogated chromatin association also compromised translocation of L2 across membranes of intracellular organelles. Thus, chromatin recruitment of L2 may in itself be a requirement for successful penetration of the limiting membrane thereby linking both processes mechanistically. Furthermore, we demonstrate that the association of L2 with mitotic chromosomes is conserved among the alpha, beta, gamma, and iota genera of Papillomaviridae. However, different binding patterns point to a certain variance amongst the different genera. Overall, our data suggest a common strategy among various PVs, in which a central region of L2 mediates tethering of vDNA to mitotic chromosomes during cell division thereby coordinating membrane

Ste12/Fab1 phosphatidylinositol-3-phosphate 5-kinase is required for nitrogen-regulated mitotic commitment and cell size control.

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David Cobley

Full Text Available Tight coupling of cell growth and cell cycle progression enable cells to adjust their rate of division, and therefore size, to the demands of proliferation in varying nutritional environments. Nutrient stress promotes inhibition of Target Of Rapamycin Complex 1 (TORC1 activity. In fission yeast, reduced TORC1 activity advances mitotic onset and switches growth to a sustained proliferation at reduced cell size. A screen for mutants, that failed to advance mitosis upon nitrogen stress, identified a mutant in the PIKFYVE 1-phosphatidylinositol-3-phosphate 5-kinase fission yeast homolog Ste12. Ste12PIKFYVE deficient mutants were unable to advance the cell cycle to reduce cell size after a nitrogen downshift to poor nitrogen (proline growth conditions. While it is well established that PI(3,5P2 signalling is required for autophagy and that Ste12PIKFYVE mutants have enlarged vacuoles (yeast lysosomes, neither a block to autophagy or mutants that independently have enlarged vacuoles had any impact upon nitrogen control of mitotic commitment. The addition of rapamycin to Ste12PIKFYVE deficient mutants reduced cell size at division to suggest that Ste12PIKFYVE possibly functions upstream of TORC1. ste12 mutants display increased Torin1 (TOR inhibitor sensitivity. However, no major impact on TORC1 or TORC2 activity was observed in the ste12 deficient mutants. In summary, Ste12PIKFYVE is required for nitrogen-stress mediated advancement of mitosis to reduce cell size at division.

Radiation and biophysical studies on cells and viruses. Progress report, February 29, 1974--March 31, 1975

International Nuclear Information System (INIS)

Cole, A.

Progress is reported on the following research projects: sedimentation analysis of chromosome components from interphase and mitotic chromosomes; electron microscopy of mitotic chromosomes; radiosensitive site analysis using short range particle beams; studies on nucleoproteins and DNA; RBE and OER for double strand breaks and single strand breaks of DNA irradiated with 241 Am alpha particles; use of 241 Am alpha particle track-ends to study the location of radiosensitive sites; gamma irradiation of nucleoprotein model systems; assembly of new equipment for the analysis of DNA size distributions; cell rejoining of DNA breaks induced by various radiations; studies on cell transformation induced by gamma radiation; localization of cellular sites for DNA breakage using labeled specific antibodies; and semiconductor properties of melanins related to preferential killing of melanoma cells. (U.S.)

[Genetic control of mitotic crossing-over in yeasts. III. Induction by 8-methoxypsoralen and long-wave UV irradiation (lambda=365 nm)].

Science.gov (United States)

Fedorova, I V; Marfin, S V

1982-02-01

The lethal effect of 8-methoxypsoralen (8-MOP) plus 365 nm light has been studied in haploid radiosensitive strains of Saccharomyces cerevisiae. The diploid of wild type and the diploid homozygous for the rad2 mutation (this mutation blocks the excision of UV-induced pyrimidine dimers) were more resistant to the lethal effect of 8-MOP plus 365 nm light than the haploid of wild type and rad2 haploid, respectively. The diploid homozygous for rad54 mutation (the mutation blocks the repair of double-strand breaks in DNA) was more sensitive than haploid rad54. The method of repeated irradiation allowed to study the capacity of radiosensitive diploids to remove monoadducts induced by 8-MOP in DNA. This process was very effective in diploids of wild type and in the rad54 rad54 diploid, while the rad2 rad2 diploid was characterized by nearly complete absence of monoadduct excision. The study of mitotic crossing over and mitotic segregation in yeast diploids, containing a pair of complementing alleles of the ade2 gene (red/pink) has shown a very high recombinogenic effect of 8-MOP plus 365 nm light. The rad2 mutation slightly increased the frequency of mitotic segregation and mitotic crossing over. The rad54 mutation decreased the frequency of mitotic segregation and entirely suppressed mitotic crossing over. The method of repeated irradiation showed that the cross-links, but not monoadducts, are the main cause of high recombinogenic effect of 8-MOP plus 365 nm light. The possible participation of different repair systems in recombinational processes induced by 8-MOP in yeast cells is discussed.

Aurora-B Mediated ATM Serine 1403 Phosphorylation Is Required For Mitotic ATM Activation and the Spindle Checkpoint

OpenAIRE

Yang, Chunying; Tang, Xi; Guo, Xiaojing; Niikura, Yohei; Kitagawa, Katsumi; Cui, Kemi; Wong, Stephen T.C.; Fu, Li; Xu, Bo

2011-01-01

The ATM kinase plays a critical role in the maintenance of genetic stability. ATM is activated in response to DNA damage and is essential for cell cycle checkpoints. Here, we report that ATM is activated in mitosis in the absence of DNA damage. We demonstrate that mitotic ATM activation is dependent on the Aurora-B kinase and that Aurora-B phosphorylates ATM on serine 1403. This phosphorylation event is required for mitotic ATM activation. Further, we show that loss of ATM function results in...

Inhibition of mitotic-specific histone phophorylation by sodium arsenite

Energy Technology Data Exchange (ETDEWEB)

Cobo, J.M. [Universidad de Alcala de Henares, Madrid (Spain); Valdez, J.G.; Gurley, L.R. [Los Alamos National Lab., NM (United States)

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.

Early post-treatment pseudo-progression amongst glioblastoma multiforme patients treated with radiotherapy and temozolomide: a retrospective analysis

International Nuclear Information System (INIS)

Gunjur, Ashray; Lau, Eddie; Taouk, Yamna; Ryan, Gail

2011-01-01

To evaluate the incidence and impact of early post-chemoradiation (cRT) 'pseudoprogression' (PsPD) amongst glioblastoma multiforme (GBM) patients treated with the current standard of care – 60 Gy conformal radiotherapy with concurrent low-dose temozolomide, followed by six cycles of high-dose temozolomide (the 'Stupp protocol'). Clinical notes and radiology reports for GBM patients treated as per the Stupp protocol were reviewed. PsPD was defined as apparent radiological progression on the first post-cRT scan, with further imaging within 3 months being stable or improving, while true early progression (ePD) was confirmed by continued progression in the subsequent 3 months following the first post-cRT scan. Of the 68 patients evaluated, 14 (21%) and 27 (40%) experienced PsPD and ePD, respectively; 3/14 (21%) patients experiencing PsPD and 14/27(52%), ePD were symptomatic for progression on first post-cRT follow-up (P = 0.096 for difference). Median survival for patients with ePD, PsPD and neither were 10.4, 27.4 and 13.0 months, respectively (P = 0.003 for ePD vs. PsPD, P = 0.19 for neither vs. PsPD groups). These data confirm a significant incidence of PsPD in post-cRT GBM patients, associated with improved median survival compared with those with neither ePD nor PsPD (not statistically significant). It appears likely that PsPD actually represents tumour response, conflicting with the traditional notion that increase in lesion size on contrast-enhanced imaging represents disease progression. Early post-cRT imaging should thus be interpreted with caution. Accompanying clinical symptoms are more commonly associated with ePD, but do not reliably distinguish PsPD from ePD.

Subjective cognitive concerns and neuropsychiatric predictors of progression to the early clinical stages of Alzheimer disease.

Science.gov (United States)

Donovan, Nancy J; Amariglio, Rebecca E; Zoller, Amy S; Rudel, Rebecca K; Gomez-Isla, Teresa; Blacker, Deborah; Hyman, Bradley T; Locascio, Joseph J; Johnson, Keith A; Sperling, Reisa A; Marshall, Gad A; Rentz, Dorene M

2014-12-01

To examine neuropsychiatric and neuropsychological predictors of progression from normal to early clinical stages of Alzheimer disease (AD). From a total sample of 559 older adults from the Massachusetts Alzheimer's Disease Research Center longitudinal cohort, 454 were included in the primary analysis: 283 with clinically normal cognition (CN), 115 with mild cognitive impairment (MCI), and 56 with subjective cognitive concerns (SCC) but no objective impairment, a proposed transitional group between CN and MCI. Two latent cognitive factors (memory-semantic, attention-executive) and two neuropsychiatric factors (affective, psychotic) were derived from the Alzheimer's Disease Centers' Uniform Data Set neuropsychological battery and Neuropsychiatric Inventory brief questionnaire. Factors were analyzed as predictors of time to progression to a worse diagnosis using a Cox proportional hazards regression model with backward elimination. Covariates included baseline diagnosis, gender, age, education, prior depression, antidepressant medication, symptom duration, and interaction terms. Higher/better memory-semantic factor score predicted lower hazard of progression (hazard ratio [HR] = 0.4 for 1 standard deviation [SD] increase, p factor score predicted higher hazard (HR = 1.3 for one SD increase, p = 0.01). No other predictors were significant in adjusted analyses. Using diagnosis as a sole predictor of transition to MCI, the SCC diagnosis carried a fourfold risk of progression compared with CN (HR = 4.1, p factors as significant predictors of more rapid progression from normal to early stages of cognitive decline and highlight the subgroup of cognitively normal elderly with SCC as those with elevated risk of progression to MCI. Copyright © 2014 American Association for Geriatric Psychiatry. Published by Elsevier Inc. All rights reserved.

Inhibition of progression of androgen-dependent prostate LNCaP tumors to androgen independence in SCID mice by oral caffeine and voluntary exercise.

Science.gov (United States)

Zheng, Xi; Cui, Xiao-Xing; Huang, Mou-Tuan; Liu, Yue; Wagner, George C; Lin, Yong; Shih, Weichung Joe; Lee, Mao-Jung; Yang, Chung S; Conney, Allan H

2012-01-01

The effect of oral caffeine or voluntary running wheel exercise (RW) alone or in combination on the progression of human androgen-dependent LNCaP prostate tumors to androgen independence in male severe combined immunodeficiency mice was determined. The mice were injected subcutaneously with LNCaP cells, and when the tumors reached a moderate size, the mice were surgically castrated and treated with caffeine (0.40 mg/ml drinking water) or RW alone or in combination for 42 days. We found that caffeine administration or RW inhibited the progression and growth of androgen-dependent LNCaP tumors to androgen independence, and a combination of the 2 regimens was more effective than the individual regimens alone. The ratios of the percent mitotic cells/caspase-3 positive cells in tumors from the caffeine-treated, RW-treated, or combination-treated mice were decreased by 34%, 38%, and 52%, respectively. Caffeine treatment increased the percentage of mitotic tumor cells undergoing apoptosis (lethal mitosis) whereas RW inhibited the increase in interleukin-6 that occurred during the progression of LNCaP tumors from androgen dependence to androgen independence. Our results indicate that oral administration of caffeine in combination with voluntary exercise may be an effective strategy for the prevention of prostate cancer progression from androgen dependence to androgen independence.

The effect of mitotic inhibitors on DNA strand size and radiation-associated break repair in Down syndrome fibroblasts

International Nuclear Information System (INIS)

Woods, W.G.; Steiner, M.E.; Kalvonjian, S.L.

1985-01-01

The effect of mitotic inhibitors on formation and repair of DNA breaks was studied in cultured fibroblasts from patients with Down syndrome in order to investigate the hypothesis that the karyotyping procedure itself may play a role in the increased chromosome breakage seen in these cells after gamma radiation exposure. Using the nondenaturing elution and alkaline elution techniques to examine fibroblasts from Down syndrome patients and from controls, no specific abnormalities in Down syndrome cells could be detected after exposure to mitotic inhibitors, including rate and extent of elution of DNA from filters as well as repair of radiation-induced DNA breaks. In both normal and Down syndrome cell strains, however, exposure to mitotic inhibitors was associated with a decrease in cellular DNA strand size, suggesting the presence of drug-induced DNA strand breaks. The mechanism of increased chromosome sensitivity of Down syndrome cells to gamma radiation remains unknown. (orig.)

Preferential Phosphorylation on Old Histones during Early Mitosis in Human Cells.

Science.gov (United States)

Lin, Shu; Yuan, Zuo-Fei; Han, Yumiao; Marchione, Dylan M; Garcia, Benjamin A

2016-07-15

How histone post-translational modifications (PTMs) are inherited through the cell cycle remains poorly understood. Canonical histones are made in the S phase of the cell cycle. Combining mass spectrometry-based technologies and stable isotope labeling by amino acids in cell culture, we question the distribution of multiple histone PTMs on old versus new histones in synchronized human cells. We show that histone PTMs can be grouped into three categories according to their distributions. Most lysine mono-methylation and acetylation PTMs are either symmetrically distributed on old and new histones or are enriched on new histones. In contrast, most di- and tri-methylation PTMs are enriched on old histones, suggesting that the inheritance of different PTMs is regulated distinctly. Intriguingly, old and new histones are distinct in their phosphorylation status during early mitosis in the following three human cell types: HeLa, 293T, and human foreskin fibroblast cells. The mitotic hallmark H3S10ph is predominantly associated with old H3 at early mitosis and becomes symmetric with the progression of mitosis. This same distribution was observed with other mitotic phosphorylation marks, including H3T3/T6ph, H3.1/2S28ph, and H1.4S26ph but not S28/S31ph on the H3 variant H3.3. Although H3S10ph often associates with the neighboring Lys-9 di- or tri-methylations, they are not required for the asymmetric distribution of Ser-10 phosphorylation on the same H3 tail. Inhibition of the kinase Aurora B does not change the distribution despite significant reduction of H3S10ph levels. However, K9me2 abundance on the new H3 is significantly reduced after Aurora B inhibition, suggesting a cross-talk between H3S10ph and H3K9me2. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Preferential Phosphorylation on Old Histones during Early Mitosis in Human Cells*

Science.gov (United States)

Lin, Shu; Yuan, Zuo-Fei; Han, Yumiao; Marchione, Dylan M.; Garcia, Benjamin A.

2016-01-01

How histone post-translational modifications (PTMs) are inherited through the cell cycle remains poorly understood. Canonical histones are made in the S phase of the cell cycle. Combining mass spectrometry-based technologies and stable isotope labeling by amino acids in cell culture, we question the distribution of multiple histone PTMs on old versus new histones in synchronized human cells. We show that histone PTMs can be grouped into three categories according to their distributions. Most lysine mono-methylation and acetylation PTMs are either symmetrically distributed on old and new histones or are enriched on new histones. In contrast, most di- and tri-methylation PTMs are enriched on old histones, suggesting that the inheritance of different PTMs is regulated distinctly. Intriguingly, old and new histones are distinct in their phosphorylation status during early mitosis in the following three human cell types: HeLa, 293T, and human foreskin fibroblast cells. The mitotic hallmark H3S10ph is predominantly associated with old H3 at early mitosis and becomes symmetric with the progression of mitosis. This same distribution was observed with other mitotic phosphorylation marks, including H3T3/T6ph, H3.1/2S28ph, and H1.4S26ph but not S28/S31ph on the H3 variant H3.3. Although H3S10ph often associates with the neighboring Lys-9 di- or tri-methylations, they are not required for the asymmetric distribution of Ser-10 phosphorylation on the same H3 tail. Inhibition of the kinase Aurora B does not change the distribution despite significant reduction of H3S10ph levels. However, K9me2 abundance on the new H3 is significantly reduced after Aurora B inhibition, suggesting a cross-talk between H3S10ph and H3K9me2. PMID:27226594

Different test systems in Aspergillus nidulans for the evaluation of mitotic gene conversion, crossing-over and non-disjunction

International Nuclear Information System (INIS)

De Bertoldi, M.; Griselli, M.; Consiglio Nazionale delle Ricerche, Pisa; Barale, R.

1980-01-01

The wide variety of the genetic alterations produced by environmental mutagens has increased the necessity of using experimental microorganisms to reveal the induction of such genetic events with short-term tests. Aspergillus nidulans, because of its well-developed genetic system and the availability of morphological markers seay to score, can be profitably used in mutagen testing. The constitution of particular diploid strains of A. nidulans able to detect the induction of mitotic gene conversion, mitotic crossing-over and mitotic non-disjunction with selective procedures are described and validated with standard mutagens: methyl methanesulphonate and UV radiation (lacking a specific genetic activity), benomyl and p-fluorophenylalanine (with a specific genetic activity). The possibility of using mammalian metabolic activation of promutagens in A. nidulans in vitro was tested with cyclophosphamide, with positive results in all the tested genetic systems. A method that increases the sensitivity of conidia to mutagenic treatments is described; its application appeared to be particularly useful in experiments on crossing-over and non-disjunction. (orig.)

A method for determining the biological effectiveness of ionizing radiation by evaluating the mitotic inhibition of Ehrlich ascites tumor cells

International Nuclear Information System (INIS)

Merkle, K.

1977-03-01

The mitotic response of mouse ascites tumor cells to in vivo 60 Co γ-irradiation (50, 100, 200, and 300 rad) was investigated on the fourth day after inoculation at 1 hour postirradiation. In the dose range applied the relationship between the mitotic index (MI) and the gamma dose (D, in rad) could be represented by MI = -35,07 lg D + 105,57. (author)

Early and progressive impairment of spinal blood flow-glucose metabolism coupling in motor neuron degeneration of ALS model mice.

Science.gov (United States)

Miyazaki, Kazunori; Masamoto, Kazuto; Morimoto, Nobutoshi; Kurata, Tomoko; Mimoto, Takahumi; Obata, Takayuki; Kanno, Iwao; Abe, Koji

2012-03-01

The exact mechanism of selective motor neuron death in amyotrophic lateral sclerosis (ALS) remains still unclear. In the present study, we performed in vivo capillary imaging, directly measured spinal blood flow (SBF) and glucose metabolism, and analyzed whether if a possible flow-metabolism coupling is disturbed in motor neuron degeneration of ALS model mice. In vivo capillary imaging showed progressive decrease of capillary diameter, capillary density, and red blood cell speed during the disease course. Spinal blood flow was progressively decreased in the anterior gray matter (GM) from presymptomatic stage to 0.80-fold of wild-type (WT) mice, 0.61 at early-symptomatic, and 0.49 at end stage of the disease. Local spinal glucose utilization (LSGU) was transiently increased to 1.19-fold in anterior GM at presymptomatic stage, which in turn progressively decreased to 0.84 and 0.60 at early-symptomatic and end stage of the disease. The LSGU/SBF ratio representing flow-metabolism uncoupling (FMU) preceded the sequential pathological changes in the spinal cord of ALS mice and was preferentially found in the affected region of ALS. The present study suggests that this early and progressive FMU could profoundly involve in the whole disease process as a vascular factor of ALS pathology, and could also be a potential target for therapeutic intervention of ALS.

INFLUENCE OF SUMIDAN ON MITOTIC DIVISION IN TRIGONELLA FOENUM GRAECUM L. SPECIES

Directory of Open Access Journals (Sweden)

Florina Mihaela Axente

2006-08-01

Full Text Available : This paper includes the cytogenetic effects induced by sumidan insectofungicide in meristematic cells of Trigonella foenum graecum L. root tips. The increase of pesticide concentration determined the decrease of mitotic index, while the frequency and the type of chromosome aberrations are much greater in treated variants, comparatively with control.

Beneficial effects of hydrogen-rich saline on early burn-wound progression in rats.

Directory of Open Access Journals (Sweden)

Song Xue Guo

Full Text Available Deep burn wounds undergo a dynamic process known as wound progression that results in a deepening and extension of the initial burn area. The zone of stasis is more likely to develop more severe during wound progression in the presence of hypoperfusion. Hydrogen has been reported to alleviate injury triggered by ischaemia/reperfusion and burns in various organs by selectively quenching oxygen free radicals. The aim of this study was to investigate the possible protective effects of hydrogen against early burn-wound progression.Deep-burn models were established through contact with a boiled, rectangular, brass comb for 20 s. Fifty-six Sprague-Dawley rats were randomly divided into sham, burn plus saline, and burn plus hydrogen-rich saline (HS groups with sacrifice and analysis at various time windows (6 h, 24 h, 48 h post burn. Indexes of oxidative stress, apoptosis and autophagy were measured in each group. The zone of stasis was evaluated using immunofluorescence staining, ELISA, and Western blot to explore the underlying effects and mechanisms post burn.The burn-induced increase in malondialdehyde was markedly reduced with HS, while the activities of endogenous antioxidant enzymes were significantly increased. Moreover, HS treatment attenuated increases in apoptosis and autophagy postburn in wounds, according to the TUNEL staining results and the expression analysis of Bax, Bcl-2, caspase-3, Beclin-1 and Atg-5 proteins. Additionally, HS lowered the level of myeloperoxidase and expression of TNF-α, IL-1β, and IL-6 in the zone of stasis while augmenting IL-10. The elevated levels of Akt phosphorylation and NF-κB p65 expression post burn were also downregulated by HS management.Hydrogen can attenuate early wound progression following deep burn injury. The beneficial effect of hydrogen was mediated by attenuating oxidative stress, which inhibited apoptosis and inflammation, and the Akt/NF-κB signalling pathway may be involved in regulating the

Isolation of a dinoflagellate mitotic cyclin by functional complementation in yeast

International Nuclear Information System (INIS)

Bertomeu, Thierry; Morse, David

2004-01-01

Dinoflagellates are parasite with permanently condensed chromosomes that lack histones and whose nuclear membrane remains intact during mitosis. These unusual nuclear characters have suggested that the typical cell cycle regulators might be slightly different than those in more typical eukaryotes. To test this, a cyclin has been isolated from the dinoflagellate Gonyaulax polyedra by functional complementation in cln123 mutant yeast. This GpCyc1 sequence contains two cyclin domains in its C-terminal region and a degradation box typical of mitotic cyclins. Similar to other dinoflagellate genes, GpCyc1 has a high copy number, with ∼5000 copies found in the Gonyaulax genome. An antibody raised against the N-terminal region of the GpCYC1 reacts with a 68 kDa protein on Western blots that is more abundant in cell cultures enriched for G2-phase cells than in those containing primarily G1-phase cells, indicating its cellular level follows a pattern expected for a mitotic cyclin. This is the first report of a cell cycle regulator cloned and sequenced from a dinoflagellate, and our results suggest control of the dinoflagellate cell cycle will be very similar to that of other organisms

Abnormal early cleavage events predict early embryo demise: sperm oxidative stress and early abnormal cleavage.

Science.gov (United States)

Burruel, Victoria; Klooster, Katie; Barker, Christopher M; Pera, Renee Reijo; Meyers, Stuart

2014-10-13

Human embryos resulting from abnormal early cleavage can result in aneuploidy and failure to develop normally to the blastocyst stage. The nature of paternal influence on early embryo development has not been directly demonstrated although many studies have suggested effects from spermatozoal chromatin packaging, DNA damage, centriolar and mitotic spindle integrity, and plasma membrane integrity. The goal of this study was to determine whether early developmental events were affected by oxidative damage to the fertilizing sperm. Survival analysis was used to compare patterns of blastocyst formation based on P2 duration. Kaplan-Meier survival curves demonstrate that relatively few embryos with short (P2 times reached blastocysts, and the two curves diverged beginning on day 4, with nearly all of the embryos with longer P2 times reaching blastocysts by day 6 (p < .01). We determined that duration of the 2nd to 3rd mitoses were sensitive periods in the presence of spermatozoal oxidative stress. Embryos that displayed either too long or too short cytokineses demonstrated an increased failure to reach blastocyst stage and therefore survive for further development. Although paternal-derived gene expression occurs later in development, this study suggests a specific role in early mitosis that is highly influenced by paternal factors.

Dietary Sodium Modulation of Aldosterone Activation and Renal Function During the Progression of Experimental Heart Failure Miller: Dietary Sodium and Early Heart Failure

Science.gov (United States)

Miller, Wayne L.; Borgeson, Daniel D.; Grantham, J. Aaron; Luchner, Andreas; Redfield, Margaret M.; Burnett, John C.

2015-01-01

Aims Aldosterone activation is central to the sodium-fluid retention that marks the progression of heart failure (HF). The actions of dietary sodium restriction, a mainstay in HF management, on cardiorenal and neuroendocrine adaptations during the progression of HF are poorly understood. The study aim was to assess the role of dietary sodium during the progression of experimental HF. Methods and Results Experimental HF was produced in a canine model by rapid right ventricular pacing which evolves from early mild HF to overt, severe HF. Dogs were fed one of three diets: 1) high sodium [250 mEq (5.8 grams) per day, n=6]; 2) standard sodium [58 mEq (1.3 grams) per day, n=6]; and 3) sodium restriction [11 mEq (0.25 grams) per day, n=6]. During the 38 day study hemodynamics, renal function, renin activity (PRA), and aldosterone were measured. Changes in hemodynamics at 38 days were similar in all three groups, as were changes in renal function. Aldosterone activation was demonstrated in all three groups, however, dietary sodium restriction, in contrast to high sodium, resulted in early (10 days) activation of PRA and aldosterone. High sodium demonstrated significant suppression of aldosterone activation over the course of HF progression. Conclusions Excessive dietary sodium restriction particularly in early stage HF results in early aldosterone activation, while normal and excess sodium intake are associated with delayed or suppressed activation. These findings warrant evaluation in humans to determine if dietary sodium manipulation, particularly during early stage HF, may have a significant impact on neuroendocrine disease progression. PMID:25823360

Observations of the first postirradiation division of HeLa cells following continuous or fractionated exposure to γ rays

International Nuclear Information System (INIS)

Mitchell, J.B.; Bedford, J.S.; Bailey, S.M.

1979-01-01

The first postirradiation division of synchronized S3 HeLa cells was studied using both continuous and fractionated irradiation treatments. Synchronized HeLa cells continuously irradiated at a dose rate of 37 rad/hr eventually accumulate in mitosis. If the continuous irradiation is stopped before the cells enter G2 or even after they have progressed for a limited time into the G2 arrest that develops, very little subsequent accumulation of cells in mitosis occurs. If they progress for a longer time into the G2 arrest, then some mitotic accumulation does occur after the irradiation is stopped. When synchronized cells were allowed to progress through G1 and S before the irradiation was started, very little cell division occurred during subsequent continuous irradiation and extensive mitotic accumulation was observed. Thus, for continuous irradiation of HeLa cells, the dose received by a cell during G2 or a G2 delay apparently determines whether it will be able to divide if it reaches mitosis. Arguing against the notion that continuous irradiation during G2 is required to produce a mitotic accumulation was the result of an expriment which showed that a similar effect was obtained using two acute doses: the first to produce a G2 delay and the second to give the necessary dose during the delay. The first dose alone resulted in little mitotic accumulation. The time of delivery of the second dose during the G2 delay affected the extent of mitotic accumulation observed. There was less mitotic accumulation when second acute doses were given early or at intermediate times during the delay than when they were given late during the G2 delay. An accumulation of cells in mitosis was also observed by using a combination of low-dose-rate irradiation to induce a G2 delay, followed immediately by an acute dose of either 500 or 1000 rad. The low-dose-rate treatment alone resulted in no mitotic accumulation

Changes in corneal sensitivity following cross-linking for progressive early-stage keratoconus

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Anelise de Medeiros Lago

2014-04-01

Full Text Available Purpose: To evaluate changes in corneal sensitivity following corneal cross-linking (CXL in patients with progressive earlier stage keratoconus. Methods: Thirty-eight eyes of 19 patients (11 women, 8 men were included in a prospective, nonrandomized clinical study. The mean patient age was 22 years (range, 18-26 years. Inclusion criteria were early stage bilateral progressive keratoconus, a transparent cornea, and a thickness of ≥440 µm in the thinnest area of the cornea. Using the Cochet-Bonnet esthesiometer, central corneal sensitivity was measured before surgery, 7 days after surgery, and once a month thereafter until recovery of baseline preoperative levels. Central corneal sensitivity >40 mm was considered normal. Results: Corneal sensitivity gradually returned to preoperative levels in all treated eyes. The mean central corneal sensitivity was 52.2, 24.0, 38.2, 42.5, 50.0, and 52.5 mm before surgery, 7 days after surgery, and at 1, 2, 3, and 4 months after surgery, respectively. Normal levels of corneal sensation, but not baseline (preoperative levels, were observed 2 months after surgery. The preoperative levels were observed 3 months after surgery. Conclusions: Our results suggest that central corneal sensitivity can be decreased for as long as 3 months after CXL for progressive earlier stage keratoconus.

Effect of AC magnetic fields on ultraviolet light-induced mutation and mitotic recombination in Saccharomyces cerevisiae

International Nuclear Information System (INIS)

Ager, D.D.; Radul, J.A.

1994-01-01

The ability of 60-Hz magnetic fields to induce genetic damage in Saccharomyces cerevisiae was studied. The frequencies of induced mutation, gene conversion, and reciprocal mitotic crossing over were measured for exposures to 1-millitesla magnetic fields alone or in combination with various preliminary exposures to 254-nm ultraviolet light at intensities of 2-50 J/m 2 . These experiments were performed using a repair-proficient strain as well as a strain incapable of excising ultraviolet-induced thymine dimers. Magnetic field exposures did not induce mutation, gene conversion, or reciprocal mitotic crossing over in either of these strains, nor did the fields influence the frequencies of ultraviolet-induced genetic events. 32 refs., 4 tabs

Adolescent Deviant Peer Clustering as an Amplifying Mechanism Underlying the Progression from Early Substance Use to Late Adolescent Dependence

Science.gov (United States)

Van Ryzin, Mark J.; Dishion, Thomas J.

2014-01-01

Background: Early substance use co-occurs with youths' self-organization into deviant peer groups in which substance use is central to social interaction. We hypothesized that the social dynamics of deviant peer groups amplify the risk of progressing from early use to later dependence, and that this influence occurs over and above escalations…

The Role Of The Integrated, Thematic Project To Learning Progress Of The Child In The Early Period

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Aida Cornelia Stoian

2016-12-01

Full Text Available In this study, we have proposed to present you the results of an empirical research in order to identify the positive aspects of the integrated, thematic project in learning progress of children in preschool. Using the observation method, we analyzed children's results regarding the objectives in the respect to the objectives in the grid. Children's progress in learning represents the confirmation and affirmation of the role of this integrated, thematic project in supporting the early learning child.

Effect of 60-Hz magnetic fields on ultraviolet light-induced mutation and mitotic recombination in Saccharomyces cerevisiae.

Science.gov (United States)

Ager, D D; Radul, J A

1992-12-01

The purpose of this study was to examine the effect of extremely low frequency (ELF) magnetic fields on the induction of genetic damage. In general, mutational studies involving ELF magnetic fields have proven negative. However, studies examining sister-chromatid exchange and chromosome aberrations have yielded conflicting results. In this study, we have examined whether 60-Hz magnetic fields are capable of inducing mutation or mitotic recombination in the yeast Saccharomyces cerevisiae. In addition we determined whether magnetic fields were capable of altering the genetic response of S. cerevisiae to UV (254 nm). We measured the frequencies of induced mutation, gene conversion and reciprocal mitotic crossing-over for exposures to magnetic fields alone (1 mT) or in combination with various UV exposures (2-50 J/m2). These experiments were performed using a repair-proficient strain (RAD+), as well as a strain of yeast (rad3) which is incapable of excising UV-induced thymine dimers. Magnetic field exposures did not induce mutation, gene conversion or reciprocal mitotic crossing-over in either of these strains, nor did the fields influence the frequencies of UV-induced genetic events.

Discrimination of bromodeoxyuridine labelled and unlabelled mitotic cells in flow cytometric bromodeoxyuridine/DNA analysis

DEFF Research Database (Denmark)

Jensen, P O; Larsen, J K; Christensen, I J

1994-01-01

Bromodeoxyuridine (BrdUrd) labelled and unlabelled mitotic cells, respectively, can be discriminated from interphase cells using a new method, based on immunocytochemical staining of BrdUrd and flow cytometric four-parameter analysis of DNA content, BrdUrd incorporation, and forward and orthogona...

Anti-mitotic potential of 7-diethylamino-3(2′-benzoxazolyl)-coumarin in 5-fluorouracil-resistant human gastric cancer cell line SNU620/5-FU

International Nuclear Information System (INIS)

Kim, Nam Hyun; Kim, Su-Nam; Oh, Joa Sub; Lee, Seokjoon; Kim, Yong Kee

2012-01-01

Highlights: ► DBC exerts antiproliferative potential against 5FU-resistant human gastric cancer cells. ► This effect is mediated by destabilization of microtubules and subsequent mitotic arrest. ► DBC enhances apoptosis via caspase activation and downregulation of antiapoptotic genes. -- Abstract: In this study, we investigate an anti-mitotic potential of the novel synthetic coumarin-based compound, 7-diethylamino-3(2′-benzoxazolyl)-coumarin, in 5-fluorouracil-resistant human gastric cancer cell line SNU-620-5FU and its parental cell SNU-620. It exerts the anti-proliferative effects with similar potencies against both cancer cells, which is mediated by destabilization of microtubules and subsequent mitotic arrest. Furthermore, this compound enhances caspase-dependent apoptotic cell death via decreased expression of anti-apoptotic genes. Taken together, our data strongly support anti-mitotic potential of 7-diethylamino-3(2′-benzoxazolyl)-coumarin against drug-resistant cancer cells which will prompt us to further develop as a novel microtubule inhibitor for drug-resistant cancer chemotherapy.

A study on β-defensin-2 and histatin-5 as a diagnostic marker of early childhood caries progression

Directory of Open Access Journals (Sweden)

Anna Jurczak

2015-01-01

Full Text Available BACKGROUND: Recently, a continuous growth of interest has been observed in antimicrobial peptides (AMPs in the light of an alarming increase in resistance of bacteria and fungi against antibiotics. AMPs are used as biomarkers in diagnosis and monitoring of oral cavity pathologies. Therefore, the determination of specific protein profiles in children diagnosed with early childhood caries (ECC might be a basis for effective screening tests and specialized examinations which may enable progression of disease METHODS: The objective of the studies was to determine the role of histatin-5 and β-defensing-2 as a diagnostic marker of early childhood caries progression. In this work, results of concentration determination of two salivary proteins (histatin-5 and β-defensin-2 were presented. In addition, bacterial profiles from dental plaque in various stages of ECC and control were marked. The assessment of alteration in the concentration of these two proteins in a study group of children with various stages of ECC and a control group consisting of children with no symptoms was performed by enzyme-linked immunosorbent assays RESULTS: The statistical analysis showed a significant increase in the concentration of histatin-5 and β-defensin-2 in the study group compared to the control group and correlated with the progression of the disease CONCLUSIONS: The confirmation of concentration changes in these proteins during the progression of dental caries may discover valuable disease progression biomarkers

Early energy deficit in Huntington disease: identification of a plasma biomarker traceable during disease progression.

Directory of Open Access Journals (Sweden)

Fanny Mochel

Full Text Available Huntington disease (HD is a fatal neurodegenerative disorder, with no effective treatment. The pathogenic mechanisms underlying HD has not been elucidated, but weight loss, associated with chorea and cognitive decline, is a characteristic feature of the disease that is accessible to investigation. We, therefore, performed a multiparametric study exploring body weight and the mechanisms of its loss in 32 presymptomatic carriers and HD patients in the early stages of the disease, compared to 21 controls. We combined this study with a multivariate statistical analysis of plasma components quantified by proton nuclear magnetic resonance ((1H NMR spectroscopy. We report evidence of an early hypermetabolic state in HD. Weight loss was observed in the HD group even in presymptomatic carriers, although their caloric intake was higher than that of controls. Inflammatory processes and primary hormonal dysfunction were excluded. (1H NMR spectroscopy on plasma did, however, distinguish HD patients at different stages of the disease and presymptomatic carriers from controls. This distinction was attributable to low levels of the branched chain amino acids (BCAA, valine, leucine and isoleucine. BCAA levels were correlated with weight loss and, importantly, with disease progression and abnormal triplet repeat expansion size in the HD1 gene. Levels of IGF1, which is regulated by BCAA, were also significantly lower in the HD group. Therefore, early weight loss in HD is associated with a systemic metabolic defect, and BCAA levels may be used as a biomarker, indicative of disease onset and early progression. The decreased plasma levels of BCAA may correspond to a critical need for Krebs cycle energy substrates in the brain that increased metabolism in the periphery is trying to provide.

Airborne urban particles (Milan winter-PM2.5) cause mitotic arrest and cell death: Effects on DNA, mitochondria, AhR binding and spindle organization

Energy Technology Data Exchange (ETDEWEB)

Gualtieri, Maurizio [Applied Cell Biology and Particles Effects, Department of Environmental Science, University Milano-Bicocca, Piazza della Scienza 1, 20126 Milano (Italy); Division of Environmental Medicine, Norwegian Institute of Public Health, P.O. Box 4404 Nydalen, N-0403 Oslo (Norway); Ovrevik, Johan [Division of Environmental Medicine, Norwegian Institute of Public Health, P.O. Box 4404 Nydalen, N-0403 Oslo (Norway); Mollerup, Steen [Section for Toxicology, National Institute of Occupational Health, N-0033 Oslo (Norway); Asare, Nana [Division of Environmental Medicine, Norwegian Institute of Public Health, P.O. Box 4404 Nydalen, N-0403 Oslo (Norway); Longhin, Eleonora [Applied Cell Biology and Particles Effects, Department of Environmental Science, University Milano-Bicocca, Piazza della Scienza 1, 20126 Milano (Italy); Dahlman, Hans-Jorgen [Division of Environmental Medicine, Norwegian Institute of Public Health, P.O. Box 4404 Nydalen, N-0403 Oslo (Norway); Camatini, Marina [Applied Cell Biology and Particles Effects, Department of Environmental Science, University Milano-Bicocca, Piazza della Scienza 1, 20126 Milano (Italy); Centre Research POLARIS, Department of Environmental Science, University Milano-Bicocca, Piazza della Scienza 1, 20126 Milano (Italy); Holme, Jorn A., E-mail: jorn.holme@fhi.no [Division of Environmental Medicine, Norwegian Institute of Public Health, P.O. Box 4404 Nydalen, N-0403 Oslo (Norway)

2011-08-01

Highlights: {yields} PM2.5 induces mitotic arrest in BEAS-2B cells. {yields} PM2.5 induces DNA damage and activates DNA damage response. {yields} AhR regulated genes (Cyp1A1, Cyp1B1 and AhRR) are upregulated after PM exposure. {yields} Mitotic spindle assembly is perturbed in PM exposed cells. - Abstract: Airborne particulate matter (PM) is considered to be an important contributor to lung diseases. In the present study we report that Milan winter-PM2.5 inhibited proliferation in human bronchial epithelial cells (BEAS-2B) by inducing mitotic arrest. The cell cycle arrest was followed by an increase in mitotic-apoptotic cells, mitotic slippage and finally an increase in 'classical' apoptotic cells. Exposure to winter-PM10 induced only a slight effect which may be due to the presence of PM2.5 in this fraction while pure combustion particles failed to disturb mitosis. Fewer cells expressing the mitosis marker phospho-histone H3 compared to cells with condensed chromosomes, suggest that PM2.5 induced premature mitosis. PM2.5 was internalized into the cells and often localized in laminar organelles, although particles without apparent plasma membrane covering were also seen. In PM-containing cells mitochondria and lysosomes were often damaged, and in mitotic cells fragmented chromosomes often appeared. PM2.5 induced DNA strands breaks and triggered a DNA-damage response characterized by increased phosphorylation of ATM, Chk2 and H2AX; as well as induced a marked increase in expression of the aryl hydrocarbon receptor (AhR)-regulated genes, CYP1A1, CYP1B1 and AhRR. Furthermore, some disturbance of the organization of microtubules was indicated. It is hypothesized that the induced mitotic arrest and following cell death was due to a premature chromosome condensation caused by a combination of DNA, mitochondrial and spindle damage.

The UK’s Modern Slavery Legislation: An Early Assessment of Progress

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Gary Craig

2017-06-01

Full Text Available In 2015, the Westminster UK government introduced a Modern Slavery Act described by its proponents as ‘world-leading’. This description was challenged at the time both inside and outside the UK. Two years on, it is possible to make a preliminary assessment of  progress with the Act and its two counterparts in Scotland and Northern Ireland. This article reviews the origins of discussions about modern slavery in the UK, describes the process leading to the passage of the Modern Slavery Act(s and attempts an early evaluation of its effectiveness. It concludes that much remains to be done to ensure that they achieve their goal of abolishing slavery in the UK.

Critical Importance of Protein 4.1 in Centrosome and Mitotic Spindle Aberrations in Breast Cancer Pathogenesis

National Research Council Canada - National Science Library

Krauss, Sharon W

2006-01-01

We proposed to test the novel hypothesis that protein 4.1 is of critical importance to centrosome and mitotic spindle aberrations that directly impact aspects of breast cancer pathogenesis. We characterized...

Radiation and biophysical studies on cells and viruses. Progress report, 1 April 1975--31 March 1976

International Nuclear Information System (INIS)

Cole, A.; Ansevin, A.T.; Corry, P.M.; Humphrey, R.M.

1976-01-01

Progress is reported on the following research projects: studies on organization of chromosomes using sedimentation analysis, electron microscopy, and radiosensitive site analysis; studies on organization of nucleoproteins and DNA using thermal denaturation experiments; distribution of radiosensitive sites in mitotic and intraphase CHO cells using track and alpha particle irradiation; gamma ray and particle irradiation studies of cellular and nucleoprotein damage; and studies of semiconductor properties of biomolecules and applications to melanin-containing cells

Oocyte formation by mitotically-active germ cells purified from ovaries of reproductive age women

Science.gov (United States)

White, Yvonne A. R.; Woods, Dori C.; Takai, Yasushi; Ishihara, Osamu; Seki, Hiroyuki; Tilly, Jonathan L.

2012-01-01

Germline stem cells that produce oocytes in vitro and fertilization-competent eggs in vivo have been identified in and isolated from adult mouse ovaries. Here we describe and validate a FACS-based protocol that can be used with adult mouse ovaries and human ovarian cortical tissue to purify rare mitotically-active cells that exhibit a gene expression profile consistent with primitive germ cells. Once established in vitro, these cells can be expanded for months and spontaneously generate 35–50 µm oocytes, as determined by morphology, gene expression and attainment of haploid (1n) status. Injection of the human germline cells, engineered to stably express GFP, into human ovarian cortical biopsies leads to formation of follicles containing GFP-positive oocytes 1–2 weeks after xenotransplantation into immunodeficient female mice. Thus, ovaries of reproductive-age women, like adult mice, possess rare mitotically-active germ cells that can be propagated in vitro as well as generate oocytes in vitro and in vivo. PMID:22366948

Oocyte formation by mitotically active germ cells purified from ovaries of reproductive-age women.

Science.gov (United States)

White, Yvonne A R; Woods, Dori C; Takai, Yasushi; Ishihara, Osamu; Seki, Hiroyuki; Tilly, Jonathan L

2012-02-26

Germline stem cells that produce oocytes in vitro and fertilization-competent eggs in vivo have been identified in and isolated from adult mouse ovaries. Here we describe and validate a fluorescence-activated cell sorting-based protocol that can be used with adult mouse ovaries and human ovarian cortical tissue to purify rare mitotically active cells that have a gene expression profile that is consistent with primitive germ cells. Once established in vitro, these cells can be expanded for months and can spontaneously generate 35- to 50-μm oocytes, as determined by morphology, gene expression and haploid (1n) status. Injection of the human germline cells, engineered to stably express GFP, into human ovarian cortical biopsies leads to formation of follicles containing GFP-positive oocytes 1-2 weeks after xenotransplantation into immunodeficient female mice. Thus, ovaries of reproductive-age women, similar to adult mice, possess rare mitotically active germ cells that can be propagated in vitro as well as generate oocytes in vitro and in vivo.

PLK1 regulation of PCNT cleavage ensures fidelity of centriole separation during mitotic exit.

Science.gov (United States)

Kim, Jaeyoun; Lee, Kwanwoo; Rhee, Kunsoo

2015-12-09

Centrioles are duplicated and segregated in close link to the cell cycle. During mitosis, daughter centrioles are disengaged and eventually separated from mother centrioles. New daughter centrioles may be generated only after centriole separation. Therefore, centriole separation is considered a licensing step for centriole duplication. It was previously known that separase specifically cleaves pericentrin (PCNT) during mitotic exit. Here we report that PCNT has to be phosphorylated by PLK1 to be a suitable substrate of separase. Phospho-resistant mutants of PCNT are not cleaved by separase and eventually inhibit centriole separation. Furthermore, phospho-mimetic PCNT mutants rescue centriole separation even in the presence of a PLK1 inhibitor. On the basis on these results, we propose that PLK1 phosphorylation is a priming step for separase-mediated cleavage of PCNT and eventually for centriole separation. PLK1 phosphorylation of PCNT provides an additional layer of regulatory mechanism to ensure the fidelity of centriole separation during mitotic exit.

DNA Strand Breaks in Mitotic Germ Cells of Caenorhabditis elegans Evaluated by Comet Assay

Science.gov (United States)

Park, Sojin; Choi, Seoyun; Ahn, Byungchan

2016-01-01

DNA damage responses are important for the maintenance of genome stability and the survival of organisms. Such responses are activated in the presence of DNA damage and lead to cell cycle arrest, apoptosis, and DNA repair. In Caenorhabditis elegans, double-strand breaks induced by DNA damaging agents have been detected indirectly by antibodies against DSB recognizing proteins. In this study we used a comet assay to detect DNA strand breaks and to measure the elimination of DNA strand breaks in mitotic germline nuclei of C. elegans. We found that C. elegans brc-1 mutants were more sensitive to ionizing radiation and camptothecin than the N2 wild-type strain and repaired DNA strand breaks less efficiently than N2. This study is the first demonstration of direct measurement of DNA strand breaks in mitotic germline nuclei of C. elegans. This newly developed assay can be applied to detect DNA strand breaks in different C. elegans mutants that are sensitive to DNA damaging agents. PMID:26903030

Body composition during early infancy and developmental progression from 1 to 5 years of age

DEFF Research Database (Denmark)

Abera, Mubarek; Tesfaye, Markos; Admassu, Bitiya

2018-01-01

aimed to examine the relation between fat mass (FM) or fat-free mass (FFM) tissues at birth and their accretion during early infancy, and later developmental progression. In a birth cohort from Ethiopia, 455 children who have BC measurement at birth and 416 who have standardised rate of BC growth during...... variables was examined using linear-mixed regression model. The finding revealed that FFM at birth was positively associated with global developmental progression from 1 to 5 years (β=1·75; 95 % CI 0·11, 3·39) and from 4 to 5 years (β=1·34; 95 % CI 0·23, 2·44) in the adjusted model. Furthermore, the rate...... of postnatal FFM tissue accretion was positively associated with development at 1 year of age (β=0·50; 95 % CI 0·01, 0·99). Neither fetal nor postnatal FM showed a significant association. In conclusion, fetal, rather than postnatal, FFM tissue accretion was associated with developmental progression...

Developmental Vitamin D (DVD) Deficiency Reduces Nurr1 and TH Expression in Post-mitotic Dopamine Neurons in Rat Mesencephalon.

Science.gov (United States)

Luan, Wei; Hammond, Luke Alexander; Cotter, Edmund; Osborne, Geoffrey William; Alexander, Suzanne Adele; Nink, Virginia; Cui, Xiaoying; Eyles, Darryl Walter

2018-03-01

Developmental vitamin D (DVD) deficiency has been proposed as an important risk factor for schizophrenia. Our previous study using Sprague Dawley rats found that DVD deficiency disrupted the ontogeny of mesencephalic dopamine neurons by decreasing the mRNA level of a crucial differentiation factor of dopamine cells, the nuclear receptor related 1 protein (Nurr1). However, it remains unknown whether this reflects a reduction in dopamine cell number or in Nurr1 expression. It is also unclear if any particular subset of developing dopamine neurons in the mesencephalon is selectively affected. In this study, we employed state-of-the-art spinning disk confocal microscopy optimized for the imaging of tissue sections and 3D segmentation to assess post-mitotic dopamine cells on a single-cell basis in the rat mesencephalon at embryonic day 15. Our results showed that DVD deficiency did not alter the number, morphology, or positioning of post-mitotic dopamine cells. However, the ratio of Nurr1+TH+ cells in the substantia nigra pars compacta (SNc) compared with the ventral tegmental area (VTA) was increased in DVD-deficient embryos. In addition, the expression of Nurr1 in immature dopamine cells and mature dopamine neurons in the VTA was decreased in DVD-deficient group. Tyrosine hydroxylase was selectively reduced in SNc of DVD-deficient mesencephalon. We conclude that DVD deficiency induced early alterations in mesencephalic dopamine development may in part explain the abnormal dopamine-related behaviors found in this model. Our findings may have broader implications for how certain environmental risk factors for schizophrenia may shape the ontogeny of dopaminergic systems and by inference increase the risk of schizophrenia.

Trisomy of the Dscr1 gene suppresses early progression of pancreatic intraepithelial neoplasia driven by oncogenic Kras

International Nuclear Information System (INIS)

Lee, Jang Choon; Shin, Jimin; Baek, Kwan-Hyuck

2013-01-01

Highlights: •A single extra copy of Dscr1 restrains progression of PanIN-1A to PanIN-1B lesions. •Dscr1 trisomy attenuates calcineurin–NFAT pathway in neoplastic ductal epithelium. •Dscr1 trisomy leads to upregulation of p15 INK4b in neoplastic ductal epithelium. •A single extra copy of Dscr1 reduces epithelial proliferation in early PanIN lesions. •Dscr1 trisomy may protect Down syndrome individuals from pancreatic cancer. -- Abstract: Individuals with Down syndrome exhibit remarkably reduced incidence of most solid tumors including pancreatic cancer. Multiple mechanisms arising from the genetic complexity underlying Down syndrome has been suggested to contribute to such a broad cancer protection. In this study, utilizing a genetically engineered mouse model of pancreatic cancer, we demonstrate that trisomy of the Down syndrome critical region-1 (Dscr1), an endogenous calcineurin inhibitor localized on chromosome 21, suppresses the progression of pancreatic intraepithelial neoplasia-1A (PanIN-1A) to PanIN-1B lesions without affecting the initiation of PanIN lesions mediated by oncogenic Kras G12D . In addition, we show that Dscr1 trisomy attenuates nuclear localization of nuclear factor of activated T-cells (NFAT) accompanied by upregulation of the p15 Ink4b tumor suppressor and reduction of cell proliferation in early PanIN lesions. Our data suggest that attenuation of calcineurin–NFAT signaling in neoplastic pancreatic ductal epithelium by a single extra copy of Dscr1 is sufficient to inhibit the progression of early PanIN lesions driven by oncogenic Kras, and thus may be a potential mechanism underlying reduced incidence of pancreatic cancer in Down syndrome individuals

Mitotic control of human papillomavirus genome-containing cells is regulated by the function of the PDZ-binding motif of the E6 oncoprotein

Science.gov (United States)

Marsh, Elizabeth K.; Delury, Craig P.; Davies, Nicholas J.; Weston, Christopher J.; Miah, Mohammed A.L.; Banks, Lawrence; Parish, Joanna L.

2017-01-01

The function of a conserved PDS95/DLG1/ZO1 (PDZ) binding motif (E6 PBM) at the C-termini of E6 oncoproteins of high-risk human papillomavirus (HPV) types contributes to the development of HPV-associated malignancies. Here, using a primary human keratinocyte-based model of the high-risk HPV18 life cycle, we identify a novel link between the E6 PBM and mitotic stability. In cultures containing a mutant genome in which the E6 PBM was deleted there was an increase in the frequency of abnormal mitoses, including multinucleation, compared to cells harboring the wild type HPV18 genome. The loss of the E6 PBM was associated with a significant increase in the frequency of mitotic spindle defects associated with anaphase and telophase. Furthermore, cells carrying this mutant genome had increased chromosome segregation defects and they also exhibited greater levels of genomic instability, as shown by an elevated level of centromere-positive micronuclei. In wild type HPV18 genome-containing organotypic cultures, the majority of mitotic cells reside in the suprabasal layers, in keeping with the hyperplastic morphology of the structures. However, in mutant genome-containing structures a greater proportion of mitotic cells were retained in the basal layer, which were often of undefined polarity, thus correlating with their reduced thickness. We conclude that the ability of E6 to target cellular PDZ proteins plays a critical role in maintaining mitotic stability of HPV infected cells, ensuring stable episome persistence and vegetative amplification. PMID:28061478

Mitotic control of human papillomavirus genome-containing cells is regulated by the function of the PDZ-binding motif of the E6 oncoprotein.

Science.gov (United States)

Marsh, Elizabeth K; Delury, Craig P; Davies, Nicholas J; Weston, Christopher J; Miah, Mohammed A L; Banks, Lawrence; Parish, Joanna L; Higgs, Martin R; Roberts, Sally

2017-03-21

The function of a conserved PDS95/DLG1/ZO1 (PDZ) binding motif (E6 PBM) at the C-termini of E6 oncoproteins of high-risk human papillomavirus (HPV) types contributes to the development of HPV-associated malignancies. Here, using a primary human keratinocyte-based model of the high-risk HPV18 life cycle, we identify a novel link between the E6 PBM and mitotic stability. In cultures containing a mutant genome in which the E6 PBM was deleted there was an increase in the frequency of abnormal mitoses, including multinucleation, compared to cells harboring the wild type HPV18 genome. The loss of the E6 PBM was associated with a significant increase in the frequency of mitotic spindle defects associated with anaphase and telophase. Furthermore, cells carrying this mutant genome had increased chromosome segregation defects and they also exhibited greater levels of genomic instability, as shown by an elevated level of centromere-positive micronuclei. In wild type HPV18 genome-containing organotypic cultures, the majority of mitotic cells reside in the suprabasal layers, in keeping with the hyperplastic morphology of the structures. However, in mutant genome-containing structures a greater proportion of mitotic cells were retained in the basal layer, which were often of undefined polarity, thus correlating with their reduced thickness. We conclude that the ability of E6 to target cellular PDZ proteins plays a critical role in maintaining mitotic stability of HPV infected cells, ensuring stable episome persistence and vegetative amplification.

Influence of irradiation at different stages of mitotic cycle upon production of sister chromatid exchanges in cultured Chinese hamster cells

International Nuclear Information System (INIS)

Antoshina, M.M.; Poryadkova, N.A.; Luchnik, N.V.

1982-01-01

Frequency of sister chromatid exchanges (SCE) and microexchanges in Chinese hamster cells has been studied by means of the method of differential staining of chromatids on irradiation at different stages of the mitotic cycle. It is shown that the irradiation enhances frequency of SCE and microexchanges if it is carried out before the end of DNA replication synthesis. Comparison of frequency depenedence of radiation-induced microexchanges and SCE at different stages of the mitotic cycle results in the conclusion that the microexchanges are none other than small SCE

Number of nuclei, mitotic activity and cell length in Cladophora sp thallus treated with cadmium and chromium

Directory of Open Access Journals (Sweden)

Monika Krajewska

2014-01-01

Full Text Available Cladophora sp., a fresh water, filamentous, multi-nucleate alga growing 16 days in the presence of cadmium and chromium at concentrations 10-4 10-8M was the subject of the experiment. Chromium ions reduced the number of nuclei and mitotic activity, and disturbed the correlation between cell length and number of nuclei, more than cadmium ions. Moreover, both tested metals caused the disappearance of cells with numerous nuclei with time of the culture. Only during the first (1-4 days of culture for both metals the concentration of 10-4M and especially of 10-8M increased the number of nuclei, mitotic index and the length of cells. Apical cells were more sensitive to metals than other thallus cells.

Progress in nucleic acid research and molecular biology

International Nuclear Information System (INIS)

Cohn, W.E.; Moldave, K.

1988-01-01

Complementary Use of Chemical Modification and Site-Directed Mutagenesis to Probe Structure-Activity Relationships in Enzymes. Mechanisms of the Antiviral Action of Inteferons. Modulation of Cellular Genes by Oncogenes. DNA Damage Produced by Ionizing Radiation in Mammalian Cells: Identities, Mechanisms of Formation, and Reparability. Human Ferritin Gene Expression. Molecular Biology of the Insulin Receptor. Cap-Binding Proteins of Eukaryotic Messenger RNA: Functions in Initiation and Control of Translation. Physical Monitoring of Meiotic and Mitotic Recombination in Yeast. Early Signals Underlying the Induction of the c-fos and c-myc Genes in Quiescent Fibroblasts: Studies with Bombesin and Other Growth Factors. Each chapter includes references

[Conservative treatment of idiopathic scoliosis with effective braces: early response to trunk asymmetry may avoid curvature progress].

Science.gov (United States)

Matussek, J; Dingeldey, E; Wagner, F; Rezai, G; Nahr, K

2014-07-01

Vertical posture of the growing child requires minute central nervous control mechanisms in order to maintain symmetry of the torso in its various activities. Scoliosis describes a constant deviation in the frontal, transverse and sagittal planes from the dynamic symmetry of the trunk. Early intervention with effective bracing, physiotherapy and sports can reverse curve progression during growth spurts, once these are identified in screening. Modern braces have a derotating and reducing effect (mirror effect) on asymmetric body volumes, thus influencing the growing torso and restoring lasting symmetry. Recent data support the use of braces to reverse progressing scoliosis.

Early career choices and successful career progression in surgery in the UK: prospective cohort studies

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Richards Jennifer MJ

2010-11-01

Full Text Available Abstract Background Changes to the structure of medical training worldwide require doctors to decide on their career specialty at an increasingly early stage after graduation. We studied trends in career choices for surgery, and the eventual career destinations, of UK graduates who declared an early preference for surgery. Methods Postal questionnaires were sent, at regular time intervals after qualification, to all medical qualifiers from all UK medical schools in selected qualification years between 1974 and 2005. They were sent in the first year after qualification, at year three and five years after qualification, and at longer time intervals thereafter. Results Responses were received from 27 749 of 38 280 doctors (73% at year one, 23 468 of 33151 (71% at year three, and 17 689 of 24 870 (71% at year five. Early career preferences showed that surgery has become more popular over the past two decades. Looking forward from early career choice, 60% of respondents (64% of men, 48% of women with a first preference for a surgical specialty at year one eventually worked in surgery (p Conclusions Surgery is a popular specialty choice in the UK. The great majority of doctors who progressed in a surgical career made an early and definitive decision to do so.

Mitotic defects lead to pervasive aneuploidy and accompany loss of RB1 activity in mouse LmnaDhe dermal fibroblasts.

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C Herbert Pratt

2011-03-01

Full Text Available Lamin A (LMNA is a component of the nuclear lamina and is mutated in several human diseases, including Emery-Dreifuss muscular dystrophy (EDMD; OMIM ID# 181350 and the premature aging syndrome Hutchinson-Gilford progeria syndrome (HGPS; OMIM ID# 176670. Cells from progeria patients exhibit cell cycle defects in both interphase and mitosis. Mouse models with loss of LMNA function have reduced Retinoblastoma protein (RB1 activity, leading to aberrant cell cycle control in interphase, but how mitosis is affected by LMNA is not well understood.We examined the cell cycle and structural phenotypes of cells from mice with the Lmna allele, Disheveled hair and ears (Lmna(Dhe. We found that dermal fibroblasts from heterozygous Lmna(Dhe (Lmna(Dhe/+ mice exhibit many phenotypes of human laminopathy cells. These include severe perturbations to the nuclear shape and lamina, increased DNA damage, and slow growth rates due to mitotic delay. Interestingly, Lmna(Dhe/+ fibroblasts also had reduced levels of hypophosphorylated RB1 and the non-SMC condensin II-subunit D3 (NCAP-D3, a mitosis specific centromere condensin subunit that depends on RB1 activity. Mitotic check point control by mitotic arrest deficient-like 1 (MAD2L1 also was perturbed in Lmna(Dhe/+ cells. Lmna(Dhe/+ fibroblasts were consistently aneuploid and had higher levels of micronuclei and anaphase bridges than normal fibroblasts, consistent with chromosome segregation defects.These data indicate that RB1 may be a key regulator of cellular phenotype in laminopathy-related cells, and suggest that the effects of LMNA on RB1 include both interphase and mitotic cell cycle control.

Mitotic Defects Lead to Pervasive Aneuploidy and Accompany Loss of RB1 Activity in Mouse LmnaDhe Dermal Fibroblasts

Science.gov (United States)

Pratt, C. Herbert; Curtain, Michelle; Donahue, Leah Rae; Shopland, Lindsay S.

2011-01-01

Background Lamin A (LMNA) is a component of the nuclear lamina and is mutated in several human diseases, including Emery-Dreifuss muscular dystrophy (EDMD; OMIM ID# 181350) and the premature aging syndrome Hutchinson-Gilford progeria syndrome (HGPS; OMIM ID# 176670). Cells from progeria patients exhibit cell cycle defects in both interphase and mitosis. Mouse models with loss of LMNA function have reduced Retinoblastoma protein (RB1) activity, leading to aberrant cell cycle control in interphase, but how mitosis is affected by LMNA is not well understood. Results We examined the cell cycle and structural phenotypes of cells from mice with the Lmna allele, Disheveled hair and ears (LmnaDhe). We found that dermal fibroblasts from heterozygous LmnaDhe (LmnaDhe/+) mice exhibit many phenotypes of human laminopathy cells. These include severe perturbations to the nuclear shape and lamina, increased DNA damage, and slow growth rates due to mitotic delay. Interestingly, LmnaDhe/+ fibroblasts also had reduced levels of hypophosphorylated RB1 and the non-SMC condensin II-subunit D3 (NCAP-D3), a mitosis specific centromere condensin subunit that depends on RB1 activity. Mitotic check point control by mitotic arrest deficient-like 1 (MAD2L1) also was perturbed in LmnaDhe /+ cells. LmnaDhe /+ fibroblasts were consistently aneuploid and had higher levels of micronuclei and anaphase bridges than normal fibroblasts, consistent with chromosome segregation defects. Conclusions These data indicate that RB1 may be a key regulator of cellular phenotype in laminopathy-related cells, and suggest that the effects of LMNA on RB1 include both interphase and mitotic cell cycle control. PMID:21464947

Functional characterisation and drug target validation of a mitotic kinesin-13 in Trypanosoma brucei.

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Kuan Yoow Chan

2010-08-01

Full Text Available Mitotic kinesins are essential for faithful chromosome segregation and cell proliferation. Therefore, in humans, kinesin motor proteins have been identified as anti-cancer drug targets and small molecule inhibitors are now tested in clinical studies. Phylogenetic analyses have assigned five of the approximately fifty kinesin motor proteins coded by Trypanosoma brucei genome to the Kinesin-13 family. Kinesins of this family have unusual biochemical properties because they do not transport cargo along microtubules but are able to depolymerise microtubules at their ends, therefore contributing to the regulation of microtubule length. In other eukaryotic genomes sequenced to date, only between one and three Kinesin-13s are present. We have used immunolocalisation, RNAi-mediated protein depletion, biochemical in vitro assays and a mouse model of infection to study the single mitotic Kinesin-13 in T. brucei. Subcellular localisation of all five T. brucei Kinesin-13s revealed distinct distributions, indicating that the expansion of this kinesin family in kinetoplastids is accompanied by functional diversification. Only a single kinesin (TbKif13-1 has a nuclear localisation. Using active, recombinant TbKif13-1 in in vitro assays we experimentally confirm the depolymerising properties of this kinesin. We analyse the biological function of TbKif13-1 by RNAi-mediated protein depletion and show its central role in regulating spindle assembly during mitosis. Absence of the protein leads to abnormally long and bent mitotic spindles, causing chromosome mis-segregation and cell death. RNAi-depletion in a mouse model of infection completely prevents infection with the parasite. Given its essential role in mitosis, proliferation and survival of the parasite and the availability of a simple in vitro activity assay, TbKif13-1 has been identified as an excellent potential drug target.

Serum carotenoids reduce progression of early atherosclerosis in the carotid artery wall among Eastern Finnish men.

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Jouni Karppi

Full Text Available BACKGROUND: Several previous epidemiologic studies have shown that high blood levels of carotenoids may be protective against early atherosclerosis, but results have been inconsistent. We assessed the association between atherosclerotic progression, measured by intima-media thickness of the common carotid artery wall, and serum levels of carotenoids. METHODS: We studied the effect of carotenoids on progression of early atherosclerosis in a population-based study. The association between concentrations of serum carotenoids, and intima-media thickness of the common carotid artery wall was explored in 840 middle-aged men (aged 46-65 years from Eastern Finland. Ultrasonography of the common carotid arteries were performed at baseline and 7-year follow-up. Serum levels of carotenoids were analyzed at baseline. Changes in mean and maximum intima media thickness of carotid artery wall were related to baseline serum carotenoid levels in covariance analyses adjusted for covariates. RESULTS: In a covariance analysis with adjustment for age, ultrasound sonographer, maximum intima media thickness, examination year, body mass index, systolic blood pressure, smoking, physical activity, serum LDL cholesterol, family history of coronary heart disease, antihypertensive medication and serum high sensitivity C-reactive protein, 7-year change in maximum intima media thickness was inversely associated with lycopene (p = 0.005, α-carotene (p = 0.002 and β-carotene (p = 0.019, respectively. CONCLUSIONS: The present study shows that high serum concentrations of carotenoids may be protective against early atherosclerosis.

Protein Biomarkers for Early Detection of Pancreatic Ductal Adenocarcinoma: Progress and Challenges.

Science.gov (United States)

Root, Alex; Allen, Peter; Tempst, Paul; Yu, Kenneth

2018-03-07

Approximately 75% of patients with pancreatic ductal adenocarcinoma are diagnosed with advanced cancer, which cannot be safely resected. The most commonly used biomarker CA19-9 has inadequate sensitivity and specificity for early detection, which we define as Stage I/II cancers. Therefore, progress in next-generation biomarkers is greatly needed. Recent reports have validated a number of biomarkers, including combination assays of proteins and DNA mutations; however, the history of translating promising biomarkers to clinical utility suggests that several major hurdles require careful consideration by the medical community. The first set of challenges involves nominating and verifying biomarkers. Candidate biomarkers need to discriminate disease from benign controls with high sensitivity and specificity for an intended use, which we describe as a two-tiered strategy of identifying and screening high-risk patients. Community-wide efforts to share samples, data, and analysis methods have been beneficial and progress meeting this challenge has been achieved. The second set of challenges is assay optimization and validating biomarkers. After initial candidate validation, assays need to be refined into accurate, cost-effective, highly reproducible, and multiplexed targeted panels and then validated in large cohorts. To move the most promising candidates forward, ideally, biomarker panels, head-to-head comparisons, meta-analysis, and assessment in independent data sets might mitigate risk of failure. Much more investment is needed to overcome these challenges. The third challenge is achieving clinical translation. To moonshot an early detection test to the clinic requires a large clinical trial and organizational, regulatory, and entrepreneurial know-how. Additional factors, such as imaging technologies, will likely need to improve concomitant with molecular biomarker development. The magnitude of the clinical translational challenge is uncertain, but interdisciplinary

Protein Biomarkers for Early Detection of Pancreatic Ductal Adenocarcinoma: Progress and Challenges

Directory of Open Access Journals (Sweden)

Alex Root

2018-03-01

Full Text Available Approximately 75% of patients with pancreatic ductal adenocarcinoma are diagnosed with advanced cancer, which cannot be safely resected. The most commonly used biomarker CA19-9 has inadequate sensitivity and specificity for early detection, which we define as Stage I/II cancers. Therefore, progress in next-generation biomarkers is greatly needed. Recent reports have validated a number of biomarkers, including combination assays of proteins and DNA mutations; however, the history of translating promising biomarkers to clinical utility suggests that several major hurdles require careful consideration by the medical community. The first set of challenges involves nominating and verifying biomarkers. Candidate biomarkers need to discriminate disease from benign controls with high sensitivity and specificity for an intended use, which we describe as a two-tiered strategy of identifying and screening high-risk patients. Community-wide efforts to share samples, data, and analysis methods have been beneficial and progress meeting this challenge has been achieved. The second set of challenges is assay optimization and validating biomarkers. After initial candidate validation, assays need to be refined into accurate, cost-effective, highly reproducible, and multiplexed targeted panels and then validated in large cohorts. To move the most promising candidates forward, ideally, biomarker panels, head-to-head comparisons, meta-analysis, and assessment in independent data sets might mitigate risk of failure. Much more investment is needed to overcome these challenges. The third challenge is achieving clinical translation. To moonshot an early detection test to the clinic requires a large clinical trial and organizational, regulatory, and entrepreneurial know-how. Additional factors, such as imaging technologies, will likely need to improve concomitant with molecular biomarker development. The magnitude of the clinical translational challenge is uncertain, but

Uncovering SUMOylation Dynamics during Cell-Cycle Progression Reveals FoxM1 as a Key Mitotic SUMO Target Protein

DEFF Research Database (Denmark)

Schimmel, Joost; Eifler, Karolin; Sigurdsson, Jón Otti

2014-01-01

Loss of small ubiquitin-like modification (SUMOylation) in mice causes genomic instability due to the missegregation of chromosomes. Currently, little is known about the identity of relevant SUMO target proteins that are involved in this process and about global SUMOylation dynamics during cell......-cycle progression. We performed a large-scale quantitative proteomics screen to address this and identified 593 proteins to be SUMO-2 modified, including the Forkhead box transcription factor M1 (FoxM1), a key regulator of cell-cycle progression and chromosome segregation. SUMOylation of FoxM1 peaks during G2 and M...... relieving FoxM1 autorepression. Cells deficient for FoxM1 SUMOylation showed increased levels of polyploidy. Our findings contribute to understanding the role of SUMOylation during cell-cycle progression....

Trisomy of the Dscr1 gene suppresses early progression of pancreatic intraepithelial neoplasia driven by oncogenic Kras

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Lee, Jang Choon; Shin, Jimin; Baek, Kwan-Hyuck, E-mail: khbaek@skku.edu

2013-10-11

Highlights: •A single extra copy of Dscr1 restrains progression of PanIN-1A to PanIN-1B lesions. •Dscr1 trisomy attenuates calcineurin–NFAT pathway in neoplastic ductal epithelium. •Dscr1 trisomy leads to upregulation of p15{sup INK4b} in neoplastic ductal epithelium. •A single extra copy of Dscr1 reduces epithelial proliferation in early PanIN lesions. •Dscr1 trisomy may protect Down syndrome individuals from pancreatic cancer. -- Abstract: Individuals with Down syndrome exhibit remarkably reduced incidence of most solid tumors including pancreatic cancer. Multiple mechanisms arising from the genetic complexity underlying Down syndrome has been suggested to contribute to such a broad cancer protection. In this study, utilizing a genetically engineered mouse model of pancreatic cancer, we demonstrate that trisomy of the Down syndrome critical region-1 (Dscr1), an endogenous calcineurin inhibitor localized on chromosome 21, suppresses the progression of pancreatic intraepithelial neoplasia-1A (PanIN-1A) to PanIN-1B lesions without affecting the initiation of PanIN lesions mediated by oncogenic Kras{sup G12D}. In addition, we show that Dscr1 trisomy attenuates nuclear localization of nuclear factor of activated T-cells (NFAT) accompanied by upregulation of the p15{sup Ink4b} tumor suppressor and reduction of cell proliferation in early PanIN lesions. Our data suggest that attenuation of calcineurin–NFAT signaling in neoplastic pancreatic ductal epithelium by a single extra copy of Dscr1 is sufficient to inhibit the progression of early PanIN lesions driven by oncogenic Kras, and thus may be a potential mechanism underlying reduced incidence of pancreatic cancer in Down syndrome individuals.

Promyelocytic leukemia bodies tether to early endosomes during mitosis.

Science.gov (United States)

Palibrk, Vuk; Lång, Emma; Lång, Anna; Schink, Kay Oliver; Rowe, Alexander D; Bøe, Stig Ove

2014-01-01

During mitosis the nuclear envelope breaks down, leading to potential interactions between cytoplasmic and nuclear components. PML bodies are nuclear structures with tumor suppressor and antiviral functions. Early endosomes, on the other hand, are cytoplasmic vesicles involved in transport and growth factor signaling. Here we demonstrate that PML bodies form stable interactions with early endosomes immediately following entry into mitosis. The 2 compartments remain stably associated throughout mitosis and dissociate in the cytoplasm of newly divided daughter cells. We also show that a minor subset of PML bodies becomes anchored to the mitotic spindle poles during cell division. The study demonstrates a stable mitosis-specific interaction between a cytoplasmic and a nuclear compartment.

Detection of mitotic nuclei in breast histopathology images using localized ACM and Random Kitchen Sink based classifier.

Science.gov (United States)

Beevi, K Sabeena; Nair, Madhu S; Bindu, G R

2016-08-01

The exact measure of mitotic nuclei is a crucial parameter in breast cancer grading and prognosis. This can be achieved by improving the mitotic detection accuracy by careful design of segmentation and classification techniques. In this paper, segmentation of nuclei from breast histopathology images are carried out by Localized Active Contour Model (LACM) utilizing bio-inspired optimization techniques in the detection stage, in order to handle diffused intensities present along object boundaries. Further, the application of a new optimal machine learning algorithm capable of classifying strong non-linear data such as Random Kitchen Sink (RKS), shows improved classification performance. The proposed method has been tested on Mitosis detection in breast cancer histological images (MITOS) dataset provided for MITOS-ATYPIA CONTEST 2014. The proposed framework achieved 95% recall, 98% precision and 96% F-score.

Effects of Mutagen-Sensitive Mus Mutations on Spontaneous Mitotic Recombination in Aspergillus

OpenAIRE

Zhao, P.; Kafer, E.

1992-01-01

Methyl methane-sulfonate (MMS)-sensitive, radiation-induced mutants of Aspergillus were shown to define nine new DNA repair genes, musK to musS. To test mus mutations for effects on mitotic recombination, intergenic crossing over was assayed between color markers and their centromeres, and intragenic recombination between two distinguishable adE alleles. Of eight mutants analyzed, four showed significant deviations from mus(+) controls in both tests. Two mutations, musK and musL, reduced reco...

CYR61 and TAZ Upregulation and Focal Epithelial to Mesenchymal Transition May Be Early Predictors of Barrett's Esophagus Malignant Progression.

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Joana Cardoso

Full Text Available Barrett's esophagus is the major risk factor for esophageal adenocarcinoma. It has a low but non-neglectable risk, high surveillance costs and no reliable risk stratification markers. We sought to identify early biomarkers, predictive of Barrett's malignant progression, using a meta-analysis approach on gene expression data. This in silico strategy was followed by experimental validation in a cohort of patients with extended follow up from the Instituto Português de Oncologia de Lisboa de Francisco Gentil EPE (Portugal. Bioinformatics and systems biology approaches singled out two candidate predictive markers for Barrett's progression, CYR61 and TAZ. Although previously implicated in other malignancies and in epithelial-to-mesenchymal transition phenotypes, our experimental validation shows for the first time that CYR61 and TAZ have the potential to be predictive biomarkers for cancer progression. Experimental validation by reverse transcriptase quantitative PCR and immunohistochemistry confirmed the up-regulation of both genes in Barrett's samples associated with high-grade dysplasia/adenocarcinoma. In our cohort CYR61 and TAZ up-regulation ranged from one to ten years prior to progression to adenocarcinoma in Barrett's esophagus index samples. Finally, we found that CYR61 and TAZ over-expression is correlated with early focal signs of epithelial to mesenchymal transition. Our results highlight both CYR61 and TAZ genes as potential predictive biomarkers for stratification of the risk for development of adenocarcinoma and suggest a potential mechanistic route for Barrett's esophagus neoplastic progression.

Influence of radiation (Co60) in pre-implant rabbit embryos: effect on mitotic index and embryonic pole malformations

International Nuclear Information System (INIS)

Approbato, M.S.; Moura, K.K.V.O.; Florencio, R.S.; Cunha Junior, C.; Garcia, R.; Faria, R.S.; Benedetti, L.N.; Goulart, F.B.

1995-01-01

We studied the effect of ionizing irradiation on 12 New Zealand rabbits (65 embryos), at three different times: at match time (zero hour), two days after and four days after, with two different irradiation doses: five c Gy and ten c Gy. Six rabbits (36 blastocysts) were used as controls. the matching instant was the zero hour. Exactly six days after (± 60 minutes) the embryos of each rabbit was picked up by flushing the uterus with culture media. the embryos were fixed in methanol for 48 hours, and colored with acid Mayer hematoxylin. The following embryo parameters were studied: mitotic index; embryonic pole malformations. There were no gross abnormalities of embryo pole. The mitotic index were altered both by the time and doses. (author)

Cdk1 Activates Pre-Mitotic Nuclear Envelope Dynein Recruitment and Apical Nuclear Migration in Neural Stem cells

Science.gov (United States)

Baffet, Alexandre D.; Hu, Daniel J.; Vallee, Richard B.

2015-01-01

Summary Dynein recruitment to the nuclear envelope is required for pre-mitotic nucleus-centrosome interactions in nonneuronal cells, and for apical nuclear migration in neural stem cells. In each case, dynein is recruited to the nuclear envelope (NE) specifically during G2, via two nuclear pore-mediated mechanisms involving RanBP2-BicD2 and Nup133-CENP-F. The mechanisms responsible for cell cycle control of this behavior are unknown. We now find that Cdk1 serves as a direct master controller for NE dynein recruitment in neural stem cells and HeLa cells. Cdk1 phosphorylates conserved sites within RanBP2 and activates BicD2 binding and early dynein recruitment. Late recruitment is triggered by a Cdk1-induced export of CENP-F from the nucleus. Forced NE targeting of BicD2 overrides Cdk1 inhibition, fully rescuing dynein recruitment and nuclear migration in neural stem cells. These results reveal how NE dynein recruitment is cell cycle regulated, and identify the trigger mechanism for apical nuclear migration in the brain. PMID:26051540

Science as an early driver of policy: child labor reform in the early Progressive Era, 1870-1900.

Science.gov (United States)

Perera, Frederica

2014-10-01

Scientific evidence is an increasingly important driver of social and environmental policy concerning child health. This trend began earlier than generally recognized. The child labor reform movement of the Gilded Age and early Progressive Era reflected not only moral and economic forces but also the dramatic advances during the later decades of the 19th century in scientific knowledge concerning children's biological and psychological vulnerability to environmental and psychosocial stressors. The growing importance of scientific information in shaping policy concerning children's health between 1870 and 1900 is illustrated by the events leading up to and following the New York State Child Labor Law of 1886. Child labor reform during this period was a critical step in the development of a science-based as well as a value-driven movement to protect children's environmental health and well-being that continues today.

Carbon-ion beam irradiation kills X-ray-resistant p53-null cancer cells by inducing mitotic catastrophe.

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Napapat Amornwichet

Full Text Available BACKGROUND AND PURPOSE: To understand the mechanisms involved in the strong killing effect of carbon-ion beam irradiation on cancer cells with TP53 tumor suppressor gene deficiencies. MATERIALS AND METHODS: DNA damage responses after carbon-ion beam or X-ray irradiation in isogenic HCT116 colorectal cancer cell lines with and without TP53 (p53+/+ and p53-/-, respectively were analyzed as follows: cell survival by clonogenic assay, cell death modes by morphologic observation of DAPI-stained nuclei, DNA double-strand breaks (DSBs by immunostaining of phosphorylated H2AX (γH2AX, and cell cycle by flow cytometry and immunostaining of Ser10-phosphorylated histone H3. RESULTS: The p53-/- cells were more resistant than the p53+/+ cells to X-ray irradiation, while the sensitivities of the p53+/+ and p53-/- cells to carbon-ion beam irradiation were comparable. X-ray and carbon-ion beam irradiations predominantly induced apoptosis of the p53+/+ cells but not the p53-/- cells. In the p53-/- cells, carbon-ion beam irradiation, but not X-ray irradiation, markedly induced mitotic catastrophe that was associated with premature mitotic entry with harboring long-retained DSBs at 24 h post-irradiation. CONCLUSIONS: Efficient induction of mitotic catastrophe in apoptosis-resistant p53-deficient cells implies a strong cancer cell-killing effect of carbon-ion beam irradiation that is independent of the p53 status, suggesting its biological advantage over X-ray treatment.

Effect of radiation on the early period of gametogenesis in Tilapia mossambika Peters

International Nuclear Information System (INIS)

Chmilevskij, D.A.; Ivojlov, A.A.

1978-01-01

Tilapia mossambica Peters larvae 10 days after hatching were X-irradiated at 350 R, and the number of germinative cells at different stages of development was followed. In the control, 10-day larvae possessed primordial germ cells and gonia; 15-day larvae had mostly gonia; in 20-day larvae some gonia were entering early prophase of meiosis; 25-day larvae possessed gonia and early meiotic prophase oocytes; and 30-day larvae had oogonia, oocytes at early prophase and at the previtellogenesis stage. After the irradiation, 13- and 14-day larvae showed some mitotic disturbances; however the mass death of germ cells was observed after their entering the pachytene stage in fishes 25 days old

A Learning Progression for Elementary Students' Functional Thinking

Science.gov (United States)

Stephens, Ana C.; Fonger, Nicole; Strachota, Susanne; Isler, Isil; Blanton, Maria; Knuth, Eric; Murphy Gardiner, Angela

2017-01-01

In this article we advance characterizations of and supports for elementary students' progress in generalizing and representing functional relationships as part of a comprehensive approach to early algebra. Our learning progressions approach to early algebra research involves the coordination of a curricular framework and progression, an…

Precommitment low-level Neurog3 expression defines a long-lived mitotic endocrine-biased progenitor pool that drives production of endocrine-committed cells

Science.gov (United States)

Bechard, Matthew E.; Bankaitis, Eric D.; Hipkens, Susan B.; Ustione, Alessandro; Piston, David W.; Yang, Yu-Ping; Magnuson, Mark A.; Wright, Christopher V.E.

2016-01-01

The current model for endocrine cell specification in the pancreas invokes high-level production of the transcription factor Neurogenin 3 (Neurog3) in Sox9+ bipotent epithelial cells as the trigger for endocrine commitment, cell cycle exit, and rapid delamination toward proto-islet clusters. This model posits a transient Neurog3 expression state and short epithelial residence period. We show, however, that a Neurog3TA.LO cell population, defined as Neurog3 transcriptionally active and Sox9+ and often containing nonimmunodetectable Neurog3 protein, has a relatively high mitotic index and prolonged epithelial residency. We propose that this endocrine-biased mitotic progenitor state is functionally separated from a pro-ductal pool and endows them with long-term capacity to make endocrine fate-directed progeny. A novel BAC transgenic Neurog3 reporter detected two types of mitotic behavior in Sox9+ Neurog3TA.LO progenitors, associated with progenitor pool maintenance or derivation of endocrine-committed Neurog3HI cells, respectively. Moreover, limiting Neurog3 expression dramatically increased the proportional representation of Sox9+ Neurog3TA.LO progenitors, with a doubling of its mitotic index relative to normal Neurog3 expression, suggesting that low Neurog3 expression is a defining feature of this cycling endocrine-biased state. We propose that Sox9+ Neurog3TA.LO endocrine-biased progenitors feed production of Neurog3HI endocrine-committed cells during pancreas organogenesis. PMID:27585590

Effect of propolis on mitotic and cellular proliferation indices in human blood lymphocytes

International Nuclear Information System (INIS)

Montoro, A.; Almonacid, M.; Villaescusa, J.; Barquinero, J.; Barrios, L.; Verdu, G.; Perez, J.

2006-01-01

The study of the frequency of chromosomal aberrations per cell is the tool used in Biological dosimetry studies. Using dose-effect calibration curve obtained in our laboratory, we can evaluate the radioprotector effect of the EEP (ethanolic extract of propolis) in cultures in vitro. Propolis is the generic name for resinous substance collected by honeybees. The results showed a reduction in chromosomal aberrations's frequency of up to 50 %. The following study consisted of analyzing human peripheral blood lymphocytes exposed to 2 Gy γ rays, in presence and absence of EEP, the change in the frequency of chromosome aberrations was analysed with biological dosimetry. The protection against the formation of dicentric and ring was dose-dependent, but there seemed to be a maximum protection, i.e. a further increase in the concentration of EEP does not show additional protection. This work studies the effect of the EEP of the cellular cycle using the mitotic and cellular proliferation index, as an alternative for the screening cytostatic activity. The results indicate that the lymphocytes which were cultures in presence of EEP exhibited a significant and dependent-concentration decrease in mitotic index and proliferation kinetics. The possible mechanisms involved in the radioprotective influence of EEP are discussed. (authors)

Effect of propolis on mitotic and cellular proliferation indices in human blood lymphocytes

Energy Technology Data Exchange (ETDEWEB)

Montoro, A.; Almonacid, M.; Villaescusa, J. [Valencia Hospital Univ. la Fe, Servicio de Proteccion Radiologica (Spain); Barquinero, J. [Barcelona Univ. Autonom, Servicio de Dosimetria Biologica, Unidad de Antropologia, Dept. de Biologia Animal, Vegetal y Ecologia, barcelona (Spain); Barrios, L. [Barcelona Univ. Autonoma, Dept. de Biologia Celular y Fisiologia. Unidad de Biologia Celular (Spain); Verdu, G. [Valencia Univ. Politecnica, Dept. de Ingenieria Quimica y Nuclear (Spain); Perez, J. [Hospital la Fe, Seccion de Radiofisica, Servicio de Radioterapia, valencia (Spain)

2006-07-01

The study of the frequency of chromosomal aberrations per cell is the tool used in Biological dosimetry studies. Using dose-effect calibration curve obtained in our laboratory, we can evaluate the radioprotector effect of the EEP (ethanolic extract of propolis) in cultures in vitro. Propolis is the generic name for resinous substance collected by honeybees. The results showed a reduction in chromosomal aberrations's frequency of up to 50 %. The following study consisted of analyzing human peripheral blood lymphocytes exposed to 2 Gy {gamma} rays, in presence and absence of EEP, the change in the frequency of chromosome aberrations was analysed with biological dosimetry. The protection against the formation of dicentric and ring was dose-dependent, but there seemed to be a maximum protection, i.e. a further increase in the concentration of EEP does not show additional protection. This work studies the effect of the EEP of the cellular cycle using the mitotic and cellular proliferation index, as an alternative for the screening cytostatic activity. The results indicate that the lymphocytes which were cultures in presence of EEP exhibited a significant and dependent-concentration decrease in mitotic index and proliferation kinetics. The possible mechanisms involved in the radioprotective influence of EEP are discussed. (authors)

A gene encoding the major beta tubulin of the mitotic spindle in Physarum polycephalum plasmodia

Energy Technology Data Exchange (ETDEWEB)

Burland, T.G.; Paul, E.C.A.; Oetliker, M.; Dove, W.F.

1988-03-01

The multinucleate plasmodium of Physarum polycephalum is unusual among eucaryotic cells in that it uses tubulins only in mitotic-spindle microtubules; cytoskeletal, flagellar, and centriolar microtubules are absent in this cell type. The authors identified a ..beta..-tubulin cDNA clone, ..beta..105, which is shown to correspond to the transcript of the betC ..beta..-tubulin locus and to encode ..beta..2 tubulin, the ..beta.. tubulin expressed specifically in the plasmodium and used exclusively in the mitotic spindle. Physarum amoebae utilize tubulins in the cytoskeleton, centrioles, and flagella, in addition to the mitotic spindle. Sequence analysis shows that ..beta..2 tubulin is only 83% identical to the two ..beta.. tubulins expressed in amoebae. This compares with 70 to 83% identity between Physarum ..beta..2 tubulin and the ..beta.. tubulins of yeasts, fungi, alga, trypanosome, fruit fly, chicken, and mouse. On the other hand, Physarum ..beta..2 tubulin is no more similar to, for example, Aspergillus ..beta.. tubulins than it is to those of Drosophila melanogaster or mammals. Several eucaryotes express at least one widely diverged ..beta.. tubulin as well as one or more ..beta.. tubulins that conform more closely to a consensus ..beta..-tubulin sequence. The authors suggest that ..beta..-tubulins diverge more when their expression pattern is restricted, especially when this restriction results in their use in fewer functions. This divergence among ..beta.. tubulins could have resulted through neutral drift. For example, exclusive use of Physarum ..beta..2 tubulin in the spindle may have allowed more amino acid substitutions than would be functionally tolerable in the ..beta.. tubulins that are utilized in multiple microtubular organelles. Alternatively, restricted use of ..beta.. tubulins may allow positive selection to operate more freely to refine ..beta..-tubulin function.

Genome-wide high-resolution mapping of UV-induced mitotic recombination events in Saccharomyces cerevisiae.

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Yi Yin

2013-10-01

Full Text Available In the yeast Saccharomyces cerevisiae and most other eukaryotes, mitotic recombination is important for the repair of double-stranded DNA breaks (DSBs. Mitotic recombination between homologous chromosomes can result in loss of heterozygosity (LOH. In this study, LOH events induced by ultraviolet (UV light are mapped throughout the genome to a resolution of about 1 kb using single-nucleotide polymorphism (SNP microarrays. UV doses that have little effect on the viability of diploid cells stimulate crossovers more than 1000-fold in wild-type cells. In addition, UV stimulates recombination in G1-synchronized cells about 10-fold more efficiently than in G2-synchronized cells. Importantly, at high doses of UV, most conversion events reflect the repair of two sister chromatids that are broken at approximately the same position whereas at low doses, most conversion events reflect the repair of a single broken chromatid. Genome-wide mapping of about 380 unselected crossovers, break-induced replication (BIR events, and gene conversions shows that UV-induced recombination events occur throughout the genome without pronounced hotspots, although the ribosomal RNA gene cluster has a significantly lower frequency of crossovers.

53BP1 nuclear bodies form around DNA lesions generated by mitotic transmission of chromosomes under replication stress

DEFF Research Database (Denmark)

Lukas, Claudia; Savic, Velibor; Bekker-Jensen, Simon

2011-01-01

stress increases the frequency of chromosomal lesions that are transmitted to daughter cells. Throughout G1, these lesions are sequestered in nuclear compartments marked by p53-binding protein 1 (53BP1) and other chromatin-associated genome caretakers. We show that the number of such 53BP1 nuclear bodies...... increases after genetic ablation of BLM, a DNA helicase associated with dissolution of entangled DNA. Conversely, 53BP1 nuclear bodies are partially suppressed by knocking down SMC2, a condensin subunit required for mechanical stability of mitotic chromosomes. Finally, we provide evidence that 53BP1 nuclear...... bodies shield chromosomal fragile sites sequestered in these compartments against erosion. Together, these data indicate that restoration of DNA or chromatin integrity at loci prone to replication problems requires mitotic transmission to the next cell generations....

EFHC1, a protein mutated in juvenile myoclonic epilepsy, associates with the mitotic spindle through its N-terminus

International Nuclear Information System (INIS)

Nijs, Laurence de; Lakaye, Bernard; Coumans, Bernard; Leon, Christine; Ikeda, Takashi; Delgado-Escueta, Antonio V.; Grisar, Thierry; Chanas, Grazyna

2006-01-01

A novel gene, EFHC1, mutated in juvenile myoclonic epilepsy (JME) encodes a protein with three DM10 domains of unknown function and one putative EF-hand motif. To study the properties of EFHC1, we expressed EGFP-tagged protein in various cell lines. In interphase cells, the fusion protein was present in the cytoplasm and in the nucleus with specific accumulation at the centrosome. During mitosis EGFP-EFHC1 colocalized with the mitotic spindle, especially at spindle poles and with the midbody during cytokinesis. Using a specific antibody, we demonstrated the same distribution of the endogenous protein. Deletion analyses revealed that the N-terminal region of EFHC1 is crucial for the association with the mitotic spindle and the midbody. Our results suggest that EFHC1 could play an important role during cell division

Early-progressive dilated cardiomyopathy in a family with Becker muscular dystrophy related to a novel frameshift mutation in the dystrophin gene exon 27.

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Tsuda, Takeshi; Fitzgerald, Kristi; Scavena, Mena; Gidding, Samuel; Cox, Mary O; Marks, Harold; Flanigan, Kevin M; Moore, Steven A

2015-03-01

We report a family in which two male siblings with Becker muscular dystrophy (BMD) developed severe dilated cardiomyopathy (DCM) and progressive heart failure (HF) at age 11 years; one died at age 14 years while awaiting heart transplant and the other underwent left ventricular assist device implantation at the same age. Genetic analysis of one sibling showed a novel frameshift mutation in exon 27 of Duchenne muscular dystrophy (DMD) gene (c.3779_3785delCTTTGGAinsGG), in which seven base pairs are deleted and two are inserted. Although this predicts an amino-acid substitution and premature termination (p.Thr1260Argfs*8), muscle biopsy dystrophin immunostaining instead indicates that the mutation is more likely to alter splicing. Despite relatively preserved skeletal muscular performance, both the siblings developed progressive HF secondary to early-onset DCM. In addition, their 7-year-old nephew with delayed gross motor development, mild proximal muscle weakness and markedly elevated serum creatine kinase level (>13 000 IU l(-1)) at 16 months was recently demonstrated to have the familial DMD mutation. Here, we report a novel genotype of BMD with early-onset DCM and progressive lethal HF during early adolescence.

Benefits of early intervention in the progression of cardiovascular disease - role of renin-angiotensin system blockade

International Nuclear Information System (INIS)

Jaffary, M.H.

2002-01-01

Atherosclerosis is a slowly progressive process. It begins early, progresses insidiously for many years, remains asymptotic and by the time it manifests as coronary artery disease or stroke, the atherosclerotic burden is immense. The question in that why does it remain asymptotic for so long? The answer lies in the fact that blood vessels are able to accommodate huge amount of plaque before the lumen becomes compromised. It is only when the plaque burden becomes severe that the lumen of the vessels becomes clogged and the symptoms start appearing. In fact the atherosclerotic process begins after the first decade of life. More so in the recent years when the fast food culture has prevailed along with significant changes in life style with decreased physical activity and increasing trend towards obesity. The process progresses steadily over the third and fourth decade of life and beyond. The fatty streaks grow to form fibrous plaques which may narrow or occlude the arterial lumen. Complex lesions may become unstable and rupture, leading to acute coronary events such as unstable angina, myocardial infarction and stroke. (author)

Early Magnetic Resonance Detection of Natalizumab-Related Progressive Multifocal Leukoencephalopathy in a Patient with Multiple Sclerosis

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Guglielmo Manenti

2013-01-01

Full Text Available Diagnosis of progressive multifocal leukoencephalopathy is usually based on the clinical presentation, on the demonstration of the brain lesions at the magnetic resonance imaging examination, and on the detection of the JC virus DNA in the cerebrospinal fluid with high sensitive polymerase chain reaction. The role of magnetic resonance imaging specifically in natalizumab-associated progressive multifocal leukoencephalopathy is strengthening, and it is gaining importance not only as an irreplaceable diagnostic tool but also as a surveillance and risk stratifying tool in treated patients. While other imaging techniques such as computed tomography lack sensitivity and specificity, magnetic resonance performed with morphological and functional sequences offers clinicians the possibility to early identify the stage of the disease and the emergence of an immune reconstitution inflammatory syndrome after natalizumab blood removal plasmapheresis.

Exclusion of NFAT5 from mitotic chromatin resets its nucleo-cytoplasmic distribution in interphase.

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Anaïs Estrada-Gelonch

Full Text Available BACKGROUND: The transcription factor NFAT5 is a major inducer of osmoprotective genes and is required to maintain the proliferative capacity of cells exposed to hypertonic stress. In response to hypertonicity, NFAT5 translocates to the nucleus, binds to regulatory regions of osmoprotective genes and activates their transcription. Besides stimulus-specific regulatory mechanisms, the activity of transcription factors in cycling cells is also regulated by the passage through mitosis, when most transcriptional processes are downregulated. It was not known whether mitosis could be a point of control for NFAT5. METHODOLOGY/PRINCIPAL FINDINGS: Using confocal microscopy we observed that NFAT5 was excluded from chromatin during mitosis in both isotonic and hypertonic conditions. Analysis of NFAT5 deletions showed that exclusion was mediated by the carboxy-terminal domain (CTD. NFAT5 mutants lacking this domain showed constitutive binding to mitotic chromatin independent of tonicity, which caused them to localize in the nucleus and remain bound to chromatin in the subsequent interphase without hypertonic stimulation. We analyzed the contribution of the CTD, DNA binding, and nuclear import and export signals to the subcellular localization of this factor. Our results indicated that cytoplasmic localization of NFAT5 in isotonic conditions required both the exclusion from mitotic DNA and active nuclear export in interphase. Finally, we identified several regions within the CTD of NFAT5, some of them overlapping with transactivation domains, which were separately capable of causing its exclusion from mitotic chromatin. CONCLUSIONS/SIGNIFICANCE: Our results reveal a multipart mechanism regulating the subcellular localization of NFAT5. The transactivating module of NFAT5 switches its function from an stimulus-specific activator of transcription in interphase to an stimulus-independent repressor of binding to DNA in mitosis. This mechanism, together with export

Reductions in Radiographic Progression in Early Rheumatoid Arthritis Over Twenty-Five Years: Changing Contribution From Rheumatoid Factor in Two Multicenter UK Inception Cohorts.

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Carpenter, Lewis; Norton, Sam; Nikiphorou, Elena; Jayakumar, Keeranur; McWilliams, Daniel F; Rennie, Kirsten L; Dixey, Josh; Kiely, Patrick; Walsh, David Andrew; Young, Adam

2017-12-01

To assess the 5-year progression of erosions and joint space narrowing (JSN) and their associations with rheumatoid factor (RF) status in 2 large, multicenter, early rheumatoid arthritis cohorts, spanning 25 years. Radiographic joint damage was recorded using the Sharp/van der Heijde (SHS) method in the Early Rheumatoid Arthritis Study (ERAS), 1986-2001, and the Early Rheumatoid Arthritis Network (ERAN), 2002-2013. Mixed-effects negative binomial regression estimated changes in radiographic damage over 5 years, including erosions and JSN, separately. RF, along with age, sex, and baseline markers of disease activity were controlled for. A total of 1,216 patients from ERAS and 446 from ERAN had radiographic data. Compared to ERAS, ERAN patients had a lower mean total SHS score at baseline (ERAN 6.2 versus ERAS 10.5; P < 0.001) and mean annual rate of change (ERAN 2.5 per year versus ERAS 6.9 per year; P < 0.001). Seventy-four percent of ERAS and 27% of ERAN patients progressed ≥5 units. Lower scores at baseline in ERAN were largely driven by reductions in JSN (ERAS 3.9 versus ERAN 1.2; P < 0.001), along with erosions (ERAS 1.9 versus ERAN 0.8; P < 0.001). RF was associated with greater progression in each cohort, but the absolute difference in mean annual rate of change for RF-positive patients was substantially higher for ERAS (RF positive 8.6 versus RF negative 5.1; P < 0.001), relative to ERAN (RF positive 2.0 versus RF negative 1.9; P = 0.855). Radiographic progression was shown to be significantly reduced between the 2 cohorts, and was associated with lower baseline damage and other factors, including changes in early disease-modifying antirheumatic drug use. The impact of RF status as a prognostic marker of clinically meaningful change in radiographic progression has markedly diminished in the context of more modern treatment. © 2017, American College of Rheumatology.

The kinetochore proteins CENP-E and CENP-F directly and specifically interact with distinct BUB mitotic checkpoint Ser/Thr kinases.

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Ciossani, Giuseppe; Overlack, Katharina; Petrovic, Arsen; Huis In 't Veld, Pim J; Koerner, Carolin; Wohlgemuth, Sabine; Maffini, Stefano; Musacchio, Andrea

2018-05-10

The segregation of chromosomes during cell division relies on the function of the kinetochores, protein complexes that physically connect chromosomes with microtubules of the spindle. The metazoan proteins, centromere protein E (CENP-E) and CENP-F, are components of a fibrous layer of mitotic kinetochores named the corona. Several of their features suggest that CENP-E and CENP-F are paralogs: they are very large (comprising approximately 2700 and 3200 residues, respectively), contain abundant predicted coiled-coil structures, are C-terminally prenylated, and are endowed with microtubule-binding sites at their termini. Moreover, CENP-E contains an ATP-hydrolyzing motor domain that promotes microtubule plus end-directed motion. Here, we show that both CENP-E and CENP-F are recruited to mitotic kinetochores independently of the main corona constituent, the Rod-Zwilch-ZW10 (RZZ) complex. We identified specific interactions of CENP-F and CENP-E with budding uninhibited by benzimidazole 1 (BUB1) and BUB1-related (BUBR1) mitotic checkpoint Ser/Thr kinases, respectively, paralogous proteins involved in mitotic checkpoint control and chromosome alignment. Whereas BUBR1 was dispensable for kinetochore localization of CENP-E, BUB1 was stringently required for CENP-F localization. Through biochemical reconstitution, we demonstrated that the CENP-E-BUBR1 and CENP-F-BUB1 interactions are direct and require similar determinants, a dimeric coiled-coil in CENP-E or CENP-F and a kinase domain in BUBR1 or BUB1. Our findings are consistent with the existence of structurally similar BUB1-CENP-F and BUBR1-CENP-E complexes, supporting the notion that CENP-E and CENP-F are evolutionarily related. Published under license by The American Society for Biochemistry and Molecular Biology, Inc.

Induction of mitotic recombination by UV and diepoxybutane and its enhancement by hydroxyurea in Saccharomyces cerevisae

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Zaborowska, D.; Swietlinska, Z.; Zuk, J. (Polska Akademia Nauk, Warsaw. Inst. Biochemii i Biofizyki)

1983-04-01

Mitotic inter- and intra-genic recombination was induced by UV-irradiation and treatment with diepoxybutane (DEB) in 2 heteroallelic diploid strains of Saccharomyces cerevisiae SBTD and D7. Induction of the events tested was strongly potentiated by plating of mutagen-treated cells on growth media containing 0.03 M hydroxyurea (HU).

p53-independent early and late apoptosis is mediated by ceramide after exposure of tumor cells to photon or carbon ion irradiation

International Nuclear Information System (INIS)

Alphonse, Gersende; Maalouf, Mira; Battiston-Montagne, Priscillia; Ardail, Dominique; Beuve, Michaël; Rousson, Robert; Taucher-Scholz, Gisela; Fournier, Claudia; Rodriguez-Lafrasse, Claire

2013-01-01

To determine whether ceramide is responsible for the induction of p53-independent early or late apoptosis in response to high- and low-Linear-Energy-Transfer (LET) irradiation. Four cell lines displaying different radiosensitivities and p53-protein status were irradiated with photons or 33.4 or 184 keV/μm carbon ions. The kinetics of ceramide production was quantified by fluorescent microscopy or High-Performance-Liquid-Chromatogaphy and the sequence of events leading to apoptosis by flow cytometry. Regardless of the p53-status, both low and high-LET irradiation induced an early ceramide production in radiosensitive cells and late in the radioresistant. This production strongly correlated with the level of early apoptosis in radiosensitive cells and delayed apoptosis in the radioresistant ones, regardless of radiation quality, tumor type, radiosensitivity, or p53-status. Inhibition of caspase activity or ceramide production showed that, for both types of radiation, ceramide is essential for the initiation of early apoptosis in radiosensitive cells and late apoptosis following mitotic catastrophe in radioresistant cells. Ceramide is a determining factor in the onset of early and late apoptosis after low and high-LET irradiation and is the mediator of the p53-independent-apoptotic pathway. We propose that ceramide is the molecular bridge between mitotic catastrophe and the commitment phase of delayed apoptosis in response to irradiation

FUNCTIONAL OUTCOMES OF HIP ARTHROSCOPY IN AN ACTIVE DUTY MILITARY POPULATION UTILIZING A CRITERION-BASED EARLY WEIGHT BEARING PROGRESSION.

Science.gov (United States)

Shaw, K Aaron; Jacobs, Jeremy M; Evanson, J Richard; Pniewski, Josh; Dickston, Michelle L; Mueller, Terry; Bojescul, John A

2017-10-01

Hip arthroscopy allows surgeons to address intra-articular pathology of the hip while avoiding more invasive open surgical dislocation. However the post-operative rehabilitation protocols have varied greatly in the literature, with many having prolonged periods of limited motion and weight bearing. The purpose of this study was to describe a criterion-based early weight bearing protocol following hip arthroscopy and investigate functional outcomes in the subjects who were active duty military. Active duty personnel undergoing hip arthroscopy for symptomatic femoroacetabular impingement were prospectively assessed in a controlled environment for the ability to incorporate early postoperative weight-bearing with the following criteria: no increased pain complaint with weight bearing and normalized gait pattern. Modified Harris Hip (HHS) and Hip Outcome score (HOS) were performed preoperatively and at six months post-op. Participants were progressed with a standard hip arthroscopy protocol. Hip flexion was limited to not exceed 90 degrees for the first three weeks post-op, with progression back to running beginning at three months. Final discharge was dependent upon the ability to run two miles at military specified pace and do a single leg broad jump within six inches of the contralateral leg without an increase in pain. Eleven participants met inclusion criteria over the study period. Crutch use was discontinued at an average of five days following surgery based on established weight bearing criteria. Only one participant required continued crutch use at 15 days. Participants' functional outcome was improved postoperatively, as demonstrated by significant increases in HOS and HHS. At the six month follow up, eight of 11 participants were able to take and complete a full Army Physical Fitness Test. Following completion of the early weight bearing rehabilitation protocol, 81% of participants were able to progress to full weight bearing by four days post

Phosphorylation of mitogen-activated protein kinase (MAPK) is required for cytokinesis and progression of cell cycle in tobacco BY-2 cells.

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Ma, Zhaowu; Yu, Guanghui

2010-02-15

The role of mitogen-activated protein kinase (MAPK) in plant cytokinesis remains largely uncharacterized. To elucidate its role, tobacco Bright Yellow-2 (BY-2) cells have been synchronized using a two-step procedure, and the different phases of the cell cycle identified by Histone 4 gene expression and the mitotic index. MAPK expression was analyzed by semi-quantitative (SQ) RT-PCR and protein gel blot analysis for phosphorylated MAPK during cell cycle progression. The SQ RT-PCR analysis indicated that MAPK expression is lower in mitosis than in interphase (G1, G2 and S). However, the amount of phosphorylated MAPK remained stable throughout the cell cycle, indicating that MAPK activity is predominantly regulated at the post-translational level and that phosphorylation of MAPK plays an important role in mitosis. Application of the specific MAPK phosphorylation inhibitor U0126 revealed that while U0126 treatment decreases the phosphorylation of MAPK and the progression from telophase to early cytokinesis is significantly inhibited. The formation of the phragmoplast is also negatively affected at this stage. These results demonstrate that MAPK phosphorylation is involved in the formation of the cell plate within the phragmoplast during cytokinesis and that MAPK predominantly functions during the cytokinesis stage of the cell cycle in tobacco BY-2 cells. Copyright 2009 Elsevier GmbH. All rights reserved.

Significance and outcome of nuclear anaplasia and mitotic index in prostatic adenocarcinomas.

Science.gov (United States)

Kır, Gozde; Sarbay, Billur Cosan; Gumus, Eyup

2016-10-01

The Gleason grading system measures architectural differentiation and disregards nuclear atypia and the cell proliferation index. Several studies have reported that nuclear grade and mitotic index (MI) are prognostically useful. This study included 232 radical prostatectomy specimens. Nuclear anaplasia (NA) was determined on the basis of nucleomegali (at least 20µm); vesicular chromatin; eosinophilic macronucleoli, nuclear lobulation, and irregular thickened nuclear membranei. The proportion of area of NA was recorded in each tumor in 10% increments. The MI was defined as the number of mitotic figures in 10 consecutive high-power fields (HPF). In univariate analysis, significant differences included associations between biochemical prostate-specific antigen recurrence (BCR) and Gleason score, extraprostatic extension, positive surgical margin, the presence of high-pathologic stage, NA≥10% of tumor area, MI≥3/10 HPF, and preoperative prostate-specific antigen. In a stepwise Cox regression model, a positive surgical margin, the presence of a NA≥10% of tumor area, and a MI of≥3/10 HPF were independent predictors of BCR after radical prostatectomy. NA≥10% of tumor area appeared to have a stronger association with outcome than MI≥3/10 HPF, as still associated with BCR when Gleason score was in the model. The results of our study showed that, in addition to the conventional Gleason grading system, NA, and MI are useful prognostic parameters while evaluating long-term prognosis in prostatic adenocarcinoma. Copyright © 2016 Elsevier Inc. All rights reserved.

Torin1-mediated TOR kinase inhibition reduces Wee1 levels and advances mitotic commitment in fission yeast and HeLa cells.

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Atkin, Jane; Halova, Lenka; Ferguson, Jennifer; Hitchin, James R; Lichawska-Cieslar, Agata; Jordan, Allan M; Pines, Jonathon; Wellbrock, Claudia; Petersen, Janni

2014-03-15

The target of rapamycin (TOR) kinase regulates cell growth and division. Rapamycin only inhibits a subset of TOR activities. Here we show that in contrast to the mild impact of rapamycin on cell division, blocking the catalytic site of TOR with the Torin1 inhibitor completely arrests growth without cell death in Schizosaccharomyces pombe. A mutation of the Tor2 glycine residue (G2040D) that lies adjacent to the key Torin-interacting tryptophan provides Torin1 resistance, confirming the specificity of Torin1 for TOR. Using this mutation, we show that Torin1 advanced mitotic onset before inducing growth arrest. In contrast to TOR inhibition with rapamycin, regulation by either Wee1 or Cdc25 was sufficient for this Torin1-induced advanced mitosis. Torin1 promoted a Polo and Cdr2 kinase-controlled drop in Wee1 levels. Experiments in human cell lines recapitulated these yeast observations: mammalian TOR (mTOR) was inhibited by Torin1, Wee1 levels declined and mitotic commitment was advanced in HeLa cells. Thus, the regulation of the mitotic inhibitor Wee1 by TOR signalling is a conserved mechanism that helps to couple cell cycle and growth controls.

The role of model organisms in the history of mitosis research.

Science.gov (United States)

Yanagida, Mitsuhiro

2014-09-02

Mitosis is a cell-cycle stage during which condensed chromosomes migrate to the middle of the cell and segregate into two daughter nuclei before cytokinesis (cell division) with the aid of a dynamic mitotic spindle. The history of mitosis research is quite long, commencing well before the discovery of DNA as the repository of genetic information. However, great and rapid progress has been made since the introduction of recombinant DNA technology and discovery of universal cell-cycle control. A large number of conserved eukaryotic genes required for the progression from early to late mitotic stages have been discovered, confirming that DNA replication and mitosis are the two main events in the cell-division cycle. In this article, a historical overview of mitosis is given, emphasizing the importance of diverse model organisms that have been used to solve fundamental questions about mitosis. Copyright © 2014 Cold Spring Harbor Laboratory Press; all rights reserved.

STAG2 and Rad21 mammalian mitotic cohesins are implicated in meiosis

OpenAIRE

Prieto, Ignacio; Pezzi, Nieves; Buesa, José M.; Kremer, Leonor; Barthelemy, Isabel; Carreiro, Candelas; Roncal, Fernando; Martínez, Alicia; Gómez, Lucio; Fernández, Raúl; Martínez-A, Carlos; Barbero, José L.

2002-01-01

STAG/SA proteins are specific cohesin complex subunits that maintain sister chromatid cohesion in mitosis and meiosis. Two members of this family, STAG1/SA1 and STAG2/SA2,‡ are classified as mitotic cohesins, as they are found in human somatic cells and in Xenopus laevis as components of the cohesinSA1 and cohesinSA2 complexes, in which the shared subunits are Rad21/SCC1, SMC1 and SMC3 proteins. A recently reported third family member, STAG3, is germinal cell-specific and is a subunit of the ...

Intracranial solitary fibrous tumors/hemangiopericytomas: first report of malignant progression.

Science.gov (United States)

Apra, Caroline; Mokhtari, Karima; Cornu, Philippe; Peyre, Matthieu; Kalamarides, Michel

2018-06-01

OBJECTIVE Meningeal solitary fibrous tumors/hemangiopericytomas (MSFTs/HPCs) are rare intracranial tumors resembling meningiomas. Their classification was redefined in 2016 by the World Health Organization (WHO) as benign Grade I fibrohyaline type, intermediate Grade II hypercellular type, and malignant highly mitotic Grade III. This grouping is based on common histological features and identification of a common NAB2-STAT6 fusion. METHODS The authors retrospectively identified 49 cases of MSFT/HPC. Clinical data were obtained from the medical records, and all cases were analyzed according to this new 2016 WHO grading classification in order to identify malignant transformations. RESULTS Recurrent surgery was performed in 18 (37%) of 49 patients. Malignant progression was identified in 5 (28%) of these 18 cases, with 3 Grade I and 2 Grade II tumors progressing to Grade III, 3-13 years after the initial surgery. Of 31 Grade III tumors treated in this case series, 16% (5/31) were proved to be malignant progressions from lower-grade tumors. CONCLUSIONS Low-grade MSFTs/HPCs can transform into higher grades as shown in this first report of such progression. This is a decisive argument in favor of a common identity for MSFT and meningeal HPC. High-grade MSFTs/HPCs tend to recur more often and be associated with reduced overall survival. Malignant progression could be one mechanism explaining some recurrences or metastases, and justifying long-term follow-up, even for patients with Grade I tumors.

Induction of mitotic recombination by UV and diepoxybutane and its enhancement by hydroxyurea in Saccharomyces cerevisae

International Nuclear Information System (INIS)

Zaborowska, D.; Swietlinska, Z.; Zuk, J.

1983-01-01

Mitotic inter- and intra-genic recombination was induced by UV-irradiation and treatment with diepoxybutane (DEB) in 2 heteroallelic diploid strains of Saccharomyces cerevisiae SBTD and D7. Induction of the events tested was strongly potentiated by plating of mutagen-treated cells on growth media containing 0.03 M hydroxyurea (HU). (orig.)

Early disease progression in patients with localized natural killer/T-cell lymphoma treated with concurrent chemoradiotherapy.

Science.gov (United States)

Yamaguchi, Motoko; Suzuki, Ritsuro; Kim, Seok Jin; Ko, Young Hyeh; Oguchi, Masahiko; Asano, Naoko; Miyazaki, Kana; Terui, Yasuhiko; Kubota, Nobuko; Maeda, Takeshi; Kobayashi, Yukio; Amaki, Jun; Soejima, Toshinori; Saito, Bungo; Shimoda, Emiko; Fukuhara, Noriko; Tsukamoto, Norifumi; Shimada, Kazuyuki; Choi, Ilseung; Utsumi, Takahiko; Ejima, Yasuo; Kim, Won Seog; Katayama, Naoyuki

2018-03-30

Prognosis of patients with localized nasal extranodal natural killer/T-cell lymphoma, nasal type (ENKL) has been improved by non-anthracycline-containing treatments such as concurrent chemoradiotherapy (CCRT). However, some patients experience early disease progression. To clarify the clinical features and outcomes of these patients, data from 165 patients with localized nasal ENKL who were diagnosed between 2000 and 2013 at 31 institutes in Japan and who received radiotherapy with dexamethasone, etoposide, ifosfamide, and carboplatin (RT-DeVIC) were retrospectively analyzed. Progression of disease within 2 years after diagnosis (POD24) was used as the definition of early progression. An independent dataset of 60 patients with localized nasal ENKL who received CCRT at Samsung Medical Center was used in the validation analysis. POD24 was documented in 23% of patients who received RT-DeVIC and in 25% of patients in the validation cohort. Overall survival (OS) from risk-defining events of the POD24 group was inferior to that of the reference group in both cohorts (P < .00001). In the RT-DeVIC cohort, pretreatment elevated levels of serum soluble interleukin-2 receptor (sIL-2R), lactate dehydrogenase, C-reactive protein, and detectable Epstein-Barr virus DNA in peripheral blood were associated with POD24. In the validation cohort, no pretreatment clinical factor associated with POD24 was identified. Our study indicates that POD24 is a strong indicator of survival in localized ENKL, despite the different CCRT regimens adopted. In the treatment of localized nasal ENKL, POD24 is useful for identifying patients who have unmet medical needs. © 2018 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.

Induced mitotic gynogenesis in common carp (Cyprinus carpio L.), optimizing irradiation dose of X- and gamma-ray

International Nuclear Information System (INIS)

Yousefian, M.; Amirinia, C.; Bercsenyi, M.; Horvath, L.

1997-01-01

Mitotic gynogenesis was induced in common carp, Cyprinus carpio L., in hatchery and laboratory conditions, using 60Co gamma-ray and X-ray for inactivation of sperm DNA and a subsequent heat shock for inducing endomitosis. The parameter examined was the dose of irradiation in the range of 70-140 Krad. Carp spermatozoa irradiated by 70-100 Krad doses showed higher motility and fertilization ability than the ones irradiated by 110-140 Krad. Sperm treated with doses of 70-90 Krad showed the same fertility rate, but lower survival rate at embryo stage compared with 100 Krad. The shock temperature and duration applied in these experiments for restoration of diploidy level were 40 degrees C plus/minus 0.1 and 2 min., respectively. The highest frequency of mitotic gynogenetic larvae was achieved by 100 Krad 60Co gamma ray at 34 min. after fertilization, - up to 12.2 percent (at 23 degrees C incubating temperature)

Combined small-molecule inhibition accelerates the derivation of functional, early-born, cortical neurons from human pluripotent stem cells

Science.gov (United States)

Qi, Yuchen; Zhang, Xin-Jun; Renier, Nicolas; Wu, Zhuhao; Atkin, Talia; Sun, Ziyi; Ozair, M. Zeeshan; Tchieu, Jason; Zimmer, Bastian; Fattahi, Faranak; Ganat, Yosif; Azevedo, Ricardo; Zeltner, Nadja; Brivanlou, Ali H.; Karayiorgou, Maria; Gogos, Joseph; Tomishima, Mark; Tessier-Lavigne, Marc; Shi, Song-Hai; Studer, Lorenz

2017-01-01

Considerable progress has been made in converting human pluripotent stem cells (hPSCs) into functional neurons. However, the protracted timing of human neuron specification and functional maturation remains a key challenge that hampers the routine application of hPSC-derived lineages in disease modeling and regenerative medicine. Using a combinatorial small-molecule screen, we previously identified conditions for the rapid differentiation of hPSCs into peripheral sensory neurons. Here we generalize the approach to central nervous system (CNS) fates by developing a small-molecule approach for accelerated induction of early-born cortical neurons. Combinatorial application of 6 pathway inhibitors induces post-mitotic cortical neurons with functional electrophysiological properties by day 16 of differentiation, in the absence of glial cell co-culture. The resulting neurons, transplanted at 8 days of differentiation into the postnatal mouse cortex, are functional and establish long-distance projections, as shown using iDISCO whole brain imaging. Accelerated differentiation into cortical neuron fates should facilitate hPSC-based strategies for disease modeling and cell therapy in CNS disorders. PMID:28112759

The effects of early hypo- and hyperthyroidism on the development of rat cerebellar cortex. III. Kinetics of cell proliferation in the external granular layer.

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Lauder, J M

1977-04-22

The effects of early hypo- and hyperthyroidism on the rates of cell acquisition and proliferation have been studied in the external granular layer (EGL) of the developing rat cerebellar cortex at 10 days of age using quantitative autoradiographic methods. Both altered thyroid states reduce the rate of cell acquisition in the EGL, but appear to do so for different reasons. Hyperthyroidism shortens the average length of the cell cycle by decreasing the duration of the pre-DNA synthetic phase (G1), indicating that excess thyroxine may exert a direct effect on the EGL. This action involves the early onset of neuronal differentiation (cessation of proliferation)46 which presumably leads to the observed decrease in the rate of cell acquisition (increased doubling time). Such differentiating cells do not, however, leave the proliferative zone or the EGL prematurely, resulting in a reduced labeling index, mitotic index, and growth fraction as non-dividing cells dilute the proliferating cell population. Hypothyroidism, on the other hand, leads to no significant change in the length of the cell cycle or in the mitotic index, but causes a decreased labeling index and growth fraction, as well as a reduced rate of cell acquisition (increased doubling time). No significant change in the amount of cell death in the EGL could be found to explain this apparent discrepancy between the rate of cell proliferation (cell cycle length) and cell acqusiition. The answer to this puzzle appears to lie in the mitotic index, which is not affected to the same extent as the labeling index, although it is also slightly reduced. If cells were to remain longer in mitosis, this could result in a decreased labeling index and growth fraction but nearly normal mitotic index and cell cycle length (as measured using the % labeled mitoses method), since those cells dropping out of the cycling population would be counted as mitoses...

Tissue inhibitor of metalloproteinase-4 is elevated in early-stage breast cancers with accelerated progression and poor clinical course.

Science.gov (United States)

Liss, Michaelann; Sreedhar, Nandhini; Keshgegian, Albert; Sauter, Guido; Chernick, Michael R; Prendergast, George C; Wallon, U Margaretha

2009-09-01

An increasing number of breast cancer patients are diagnosed with small, localized, early-stage tumors. These patients are typically thought to have a good prognosis for long-term disease-free survival, but epidemiological studies indicate that up to 30% may have a recurrence within 3 to 5 years of diagnosis. Identifying patients with a high risk of recurrence and/or progression is important because they could be more aggressively treated at diagnosis to improve their chances for disease-free survival. Recent evidence suggests that elevated levels of the matrix metalloproteinase inhibitor, tissue inhibitor of metalloproteinase (TIMP)-4, are associated with malignant progression of ductal carcinoma in situ, a precancerous lesion. To examine the association of TIMP-4 with survival outcomes, we conducted a retrospective immunohistochemical analysis of 314 cases from patients with early-stage disease, defined as tumors smaller than 2 cm and no spread to lymph nodes (tumor-node-metastasis staging: T1N0MX). We found that tumors with elevated levels of TIMP-4 were correlated with a reduced probability of long-term disease-free survival, especially in patients with estrogen receptor-negative tumors. Our findings prompt further evaluation of TIMP-4 as a simple prognostic marker that may help identify patients with early-stage breast cancer who could benefit from more aggressive treatment at diagnosis.

Science as an Early Driver of Policy: Child Labor Reform in the Early Progressive Era, 1870–1900

Science.gov (United States)

2014-01-01

Scientific evidence is an increasingly important driver of social and environmental policy concerning child health. This trend began earlier than generally recognized. The child labor reform movement of the Gilded Age and early Progressive Era reflected not only moral and economic forces but also the dramatic advances during the later decades of the 19th century in scientific knowledge concerning children’s biological and psychological vulnerability to environmental and psychosocial stressors. The growing importance of scientific information in shaping policy concerning children’s health between 1870 and 1900 is illustrated by the events leading up to and following the New York State Child Labor Law of 1886. Child labor reform during this period was a critical step in the development of a science-based as well as a value-driven movement to protect children’s environmental health and well-being that continues today. PMID:25121809

Characteristic of muscle involvement evaluated by CT scans in early stages of progressive muscular dystrophy

International Nuclear Information System (INIS)

Arai, Yumi

1993-01-01

Muscle CT scans were performed in order to compare the characteristic distribution of progressive muscle involvement in the early stages of Duchenne type (DMD) and Fukuyama type muscular dystrophy (FCMD). Muscle images at the levels of the 3rd lumbar vertebra, thigh and calf were assessed by visual inspection, and mean CT numbers calculated for individual muscles were statistically analysed. On visual inspection, intramuscular low density areas and muscular atrophy were observed in the muscles of older patients with either disease. These changes were, however, more extensive at thigh level in DMD, and at calf level in FCMD. Nevertheless, the mean CT numbers of muscles in which only slight changes were grossly visible on CT scans displayed progressive decreases with increasing age. Moreover, a significant negative relationship was recognizable between age and mean CT number in almost all muscles examined. Comparison of the slopes of the regression lines revealed that the so-called selective pattern of muscle involvement characteristic of the symptomatic stage had already partially manifested in the preclinical or early stages of both diseases. In FCMD, the rates of decrease in CT numbers were extremely rapid for calf muscles as compared with those in DMD, indicating that this is one reason for FCMD patients never becoming ambulatory. However, for almost all of the other muscles, the CT numbers in FCMD decreased in parallel with the corresponding CT numbers in DMD; thus, these diseases displayed a similarity in the pattern of muscle involvement, despite their different pathogenetic mechanisms and inheritance patterns. (author)

Relative cataractogenic effects of X rays, fission-spectrum neutrons, and 56Fe particles: A comparison with mitotic effects

International Nuclear Information System (INIS)

Riley, E.F.; Lindgren, A.L.; Andersen, A.L.; Miller, R.C.; Ainsworth, E.J.

1991-01-01

The eyes of Sprague-Dawley rats were irradiated with doses of 2.5-10 Gy 250-kVp X rays, 1.25-2.25 Gy fission-spectrum neutrons (approximately 0.85 MeV), or 0.1-2.0 Gy 600-MeV/A 56Fe particles. Lens opacifications were evaluated for 51-61 weeks following X and neutron irradiations and for 87 weeks following X and 56Fe-particle irradiations. Average stage of opacification was determined relative to time after irradiation, and the time required for 50% of the irradiated lenses to achieve various stages (T50) was determined as a function of radiation dose. Data from two experiments were combined in dose-effect curves as T50 experimental values taken as percentages of the respective T50 control values (T50-% control). Simple exponential curves best describe dose responsiveness for both high-LET radiations. For X rays, a shallow dose-effect relationship (shoulder) up to 4.5 Gy was followed at higher doses by a steeper exponential dose-effect relationship. As a consequence, RBE values for the high-LET radiations are dose dependent. Dose-effect curves for cataracts were compared to those for mitotic abnormalities observed when quiescent lens epithelial cells were stimulated mechanically to proliferate at various intervals after irradiation. Neutrons were about 1.6-1.8 times more effective than 56Fe particles for inducing both cataracts and mitotic abnormalities. For stage 1 and 2 cataracts, the X-ray Dq was 10-fold greater and the D0 was similar to those for mitotic abnormalities initially expressed after irradiation

Phosphohistone-H3 (PHH3) is prognostic relevant in Merkel cell carcinomas but Merkel cell polyomavirus is a more powerful prognostic factor than AJCC clinical stage, PHH3, Ki-67 or mitotic indices.

Science.gov (United States)

Iwasaki, Takeshi; Matsushita, Michiko; Nonaka, Daisuke; Kato, Masako; Nagata, Keiko; Murakami, Ichiro; Hayashi, Kazuhiko

2015-08-01

Merkel cell carcinomas (MCCs) associated with Merkel cell polyomavirus (MCPyV) have better prognosis than those without MCPyV. The relationship between mitotic index (MI) and MCC outcome has remained elusive because of the difficulty in differentiating mitotic cells from apoptotic ones. We evaluated the role of phosphohistone-H3 (PHH3) (Ser10), a new mitotic count biomarker, in MCPyV-positive or -negative MCC patients, and assessed its prognostic value in comparison to Ki-67 labeling index or MI using hematoxylin and eosin (HE) staining. We compared the prognostic value of PHH3 mitotic index with that of MI by HE in 19 MCPyV-positive and 9 MCPyV-negative MCC patients. PHH3-positive immunoreactivity was mostly observed in mitotic figures. Multivariate analysis significantly showed that MCPyV status (HR, 0.004; 95% CI 0.0003-0.058) and the American Joint Committee of Cancer (AJCC) stage (HR, 5.02; 95% CI 1.23-20.51) were observed as significantly independent prognostic factors for OS. PHH3-positive cell counts/10 HPF was a slightly significant independent prognostic factor for OS (HR, 4.96; 95% CI 0.93-26.55). PHH3-positive MI and MCPyV status in MCC patients are useful in prognostication, although MCPyV-infection is a more powerful prognostic factor in MCCs than the AJCC scheme on proliferation or mitotic indices. © 2015 Japanese Society of Pathology and Wiley Publishing Asia Pty Ltd.

A Critical Role of TET1/2 Proteins in Cell-Cycle Progression of Trophoblast Stem Cells

Directory of Open Access Journals (Sweden)

Stephanie Chrysanthou

2018-04-01

Full Text Available Summary: The ten-eleven translocation (TET proteins are well known for their role in maintaining naive pluripotency of embryonic stem cells. Here, we demonstrate that, jointly, TET1 and TET2 also safeguard the self-renewal potential of trophoblast stem cells (TSCs and have partially redundant roles in maintaining the epithelial integrity of TSCs. For the more abundantly expressed TET1, we show that this is achieved by binding to critical epithelial genes, notably E-cadherin, which becomes hyper-methylated and downregulated in the absence of TET1. The epithelial-to-mesenchymal transition phenotype of mutant TSCs is accompanied by centrosome duplication and separation defects. Moreover, we identify a role of TET1 in maintaining cyclin B1 stability, thereby acting as facilitator of mitotic cell-cycle progression. As a result, Tet1/2 mutant TSCs are prone to undergo endoreduplicative cell cycles leading to the formation of polyploid trophoblast giant cells. Taken together, our data reveal essential functions of TET proteins in the trophoblast lineage. : TET proteins are well known for their role in pluripotency. Here, Hemberger and colleagues show that TET1 and TET2 are also critical for maintaining the epithelial integrity of trophoblast stem cells. TET1/2 ensure mitotic cell-cycle progression by stabilizing cyclin B1 and by regulating centrosome organization. These insights reveal the importance of TET proteins beyond their role in epigenome remodeling. Keywords: TET proteins, trophoblast stem cells, cell cycle, endoreduplication, self-renewal, mitosis, trophoblast giant cells, differentiation

Progression of brain atrophy in the early stages of Parkinson's disease: a longitudinal tensor-based morphometry study in de novo patients without cognitive impairment.

Science.gov (United States)

Tessa, Carlo; Lucetti, Claudio; Giannelli, Marco; Diciotti, Stefano; Poletti, Michele; Danti, Sabrina; Baldacci, Filippo; Vignali, Claudio; Bonuccelli, Ubaldo; Mascalchi, Mario; Toschi, Nicola

2014-08-01

The presence of brain atrophy and its progression in early Parkinson's disease (PD) are still a matter of debate, particularly in patients without cognitive impairment. The aim of this longitudinal study was to assess whether PD patients who remain cognitively intact develop progressive atrophic changes in the early stages of the disease. For this purpose, we employed high-resolution T1-weighted MR imaging to compare 22 drug-naïve de novo PD patients without cognitive impairment to 17 age-matched control subjects, both at baseline and at three-year follow-up. We used tensor-based morphometry to explore the presence of atrophic changes at baseline and to compute yearly atrophy rates, after which we performed voxel-wise group comparisons using threshold-free cluster enhancement. At baseline, we did not observe significant differences in regional atrophy in PD patients with respect to control subjects. In contrast, PD patients showed significantly higher yearly atrophy rates in the prefrontal cortex, anterior cingulum, caudate nucleus, and thalamus when compared to control subjects. Our results indicate that even cognitively preserved PD patients show progressive cortical and subcortical atrophic changes in regions related to cognitive functions and that these changes are already detectable in the early stages of the disease. Copyright © 2014 Wiley Periodicals, Inc.

Radiation-induced mitotic and meiotic aneuploidy in the yeast Saccharomyces cerevisiae.

Science.gov (United States)

Parry, J M; Sharp, D; Tippins, R S; Parry, E M

1979-06-01

A number of genetic systems are described which in yeast may be used to monitor the induction of chromosome aneuploidy during both mitotic and meiotic cell division. Using these systems we have been able to demonstrate the induction of both monosomic and trisomic cells in mitotically dividing cells and disomic spores in meiotically dividing cells after both UV light and X-ray exposure. The frequency of UV-light-induced monosomic colonies were reduced by post-treatment with photoreactivity light and both UV-light- and X-ray-induced monosomic colonies were reduced by liquid holding post-treatment under non-nutrient conditions. Both responses indicate an involvement of DNA-repair mechanisms in the removal of lesions which may lead to monosomy in yeast. This was further confirmed by the response of an excision-defective yeast strain which showed considerably increased sensitivity to the induction of monosomic colonies by UV-light treatment at low doses. Yeast cultures irradiated at different stages of growth showed variation in their responses to both UV-light and X-rays, cells at the exponential phase of growth show maximum sensitivity to the induction of monosomic colonies at low doses whereas stationary phase cultures showed maximum induction of monosomic colonies at high does. The frequencies of X-ray-induced chromosome aneuploidy during meiosis leading to the production of disomic spores was shown to be dependent upon the stage of meiosis at which the yeast cells were exposed to radiation. Cells which had proceeded beyond the DNA synthetic stage of meiosis were shown to produce disomic spores at considerably lower radiation doses than those cells which had only recently been inoculated into sporulation medium. The results obtained suggest that the yeast sustem may be suitable for the study of sensitivities of the various stages of meiotic cell division to the induction of chromosome aneuploidy after radiation exposure.

Automatic analysis of dividing cells in live cell movies to detect mitotic delays and correlate phenotypes in time.

Science.gov (United States)

Harder, Nathalie; Mora-Bermúdez, Felipe; Godinez, William J; Wünsche, Annelie; Eils, Roland; Ellenberg, Jan; Rohr, Karl

2009-11-01

Live-cell imaging allows detailed dynamic cellular phenotyping for cell biology and, in combination with small molecule or drug libraries, for high-content screening. Fully automated analysis of live cell movies has been hampered by the lack of computational approaches that allow tracking and recognition of individual cell fates over time in a precise manner. Here, we present a fully automated approach to analyze time-lapse movies of dividing cells. Our method dynamically categorizes cells into seven phases of the cell cycle and five aberrant morphological phenotypes over time. It reliably tracks cells and their progeny and can thus measure the length of mitotic phases and detect cause and effect if mitosis goes awry. We applied our computational scheme to annotate mitotic phenotypes induced by RNAi gene knockdown of CKAP5 (also known as ch-TOG) or by treatment with the drug nocodazole. Our approach can be readily applied to comparable assays aiming at uncovering the dynamic cause of cell division phenotypes.

Spousal Recollections of Early Signs of Primary Progressive Aphasia

Science.gov (United States)

Pozzebon, Margaret; Douglas, Jacinta; Ames, David

2018-01-01

Background: Although primary progressive aphasia (PPA) is characterized by progressive loss of language and communication skills, knowledge about the earliest emerging signs announcing the onset of this condition is limited. Aims: To explore spousal recollections regarding the earliest signs of PPA and to compare the nature of the earliest…

Glaucoma Monitoring in a Clinical Setting Glaucoma Progression Analysis vs Nonparametric Progression Analysis in the Groningen Longitudinal Glaucoma Study

NARCIS (Netherlands)

Wesselink, Christiaan; Heeg, Govert P.; Jansonius, Nomdo M.

Objective: To compare prospectively 2 perimetric progression detection algorithms for glaucoma, the Early Manifest Glaucoma Trial algorithm (glaucoma progression analysis [GPA]) and a nonparametric algorithm applied to the mean deviation (MD) (nonparametric progression analysis [NPA]). Methods:

Role of DNA Methylation in Altering Gene Expression During the Early Stages of Human Breast Cancer Progression in the MCF10AT Xenograft Model

National Research Council Canada - National Science Library

Christman, Judith

2004-01-01

...) Collect microdissected tissue representative of each of the morphologically different stages of early breast cancer progression in the MCFlOAT model to obtain RNA and DNA for miroarray analysis...

Variations in DNA synthesis and mitotic indices in hepatocytes and sinusoid litoral cells of adult intact male mouse along a circadian time span.

Science.gov (United States)

Surur, J M; Moreno, F R; Badrán, A F; Llanos, J M

1985-01-01

Variations of DNA synthesis (DNAS) and mitotic indices along a circadian time span are described in the hepatocyte and sinusoid litoral cell populations of adult intact male mouse liver. Standardized (light from 0600 to 1800) mice were killed in groups of six to nine animals, every 2-4 hr along a circadian time span. Hepatocytes show significant peaks in the synthesis of DNA and the mitotic activity at 0200 and 1400, respectively. These results correspond to those previously described by us in young immature liver, regenerating liver and hepatomas. The phase differences between these peaks and the differences between their absolute values are discussed. Also considered are the practical consequences of our findings for experimental design. The curve of DNA synthesis of sinusoid litoral cells show a peak at 0200. The mitotic index show a bimodal waveform with peaks at 0800 and 2000. The existence of four different cell populations composing the so called sinusoid litoral cells and also the migration into and out of the liver of some macrophages considered as litoral (Kupffer) cells in our counts, makes interpretation of the curves somewhat complicated and deserves further analysis.

Human SGT interacts with Bag-6/Bat-3/Scythe and cells with reduced levels of either protein display persistence of few misaligned chromosomes and mitotic arrest

International Nuclear Information System (INIS)

Winnefeld, Marc; Grewenig, Annabel; Schnoelzer, Martina; Spring, Herbert; Knoch, Tobias A.; Gan, Eugene C.; Rommelaere, Jean; Cziepluch, Celina

2006-01-01

The human small glutamine-rich TPR-containing protein (hSGT) is essential for cell division since RNA-interference-mediated strong reduction of hSGT protein levels causes mitotic arrest (M. Winnefeld, J. Rommelaere, and C. Cziepluch, The human small glutamine-rich TPR-containing protein is required for progress through cell division, Exp. Cell Res. 293 (2004), 43-57). Analysis of HeLa cells expressing a histone 2A-YFP fusion protein revealed the continuous presence of few mislocalized chromosomes close to the spindle poles as possible cause for hSGT depletion-dependent prometaphase arrest. Cells unable to rescue these mislocalized chromosomes into the metaphase plate died at this stage through apoptosis. In order to address hSGT function at the molecular level, mass spectrometry analysis of proteins which co-immunoprecipitated with Flag-tagged hSGT was performed. Thereby, Hsp70 and Bag-6/Bat-3/Scythe were identified as novel hSGT interaction partners while interaction with Hsc70 was confirmed. Results obtained with truncated versions of the hSGT protein revealed that Bag-6/Bat-3/Scythe and Hsp70 or Hsc70 were independently able to form complexes with hSGT. Interaction of hSGT with Hsc70, Hsp70 or Bag-6/Bat-3/Scythe was demonstrated in prometaphase, thereby suggesting a possible role for complexes containing hSGT and distinct (co)-chaperones during mitosis. Finally, cells from populations with reduced levels of Bag-6/Bat-3/Scythe also displayed persistence of mislocalized chromosomes and mitotic arrest, which strongly indicated that hSGT-Bag-6/Bat-3/Scythe complexes could be directly or indirectly required for complete chromosome congression

Sonic hedgehog-expressing basal cells are general post-mitotic precursors of functional taste receptor cells

Science.gov (United States)

Miura, Hirohito; Scott, Jennifer K.; Harada, Shuitsu; Barlow, Linda A.

2014-01-01

Background Taste buds contain ~60 elongate cells and several basal cells. Elongate cells comprise three functional taste cell types: I - glial cells, II - bitter/sweet/umami receptor cells, and III - sour detectors. Although taste cells are continuously renewed, lineage relationships among cell types are ill-defined. Basal cells have been proposed as taste bud stem cells, a subset of which express Sonic hedgehog (Shh). However, Shh+ basal cells turnover rapidly suggesting that Shh+ cells are precursors of some or all taste cell types. Results To fate map Shh-expressing cells, mice carrying ShhCreERT2 and a high (CAG-CAT-EGFP) or low (R26RLacZ) efficiency reporter allele were given tamoxifen to activate Cre in Shh+ cells. Using R26RLacZ, lineage-labeled cells occur singly within buds, supporting a post-mitotic state for Shh+ cells. Using either reporter, we show that Shh+ cells differentiate into all three taste cell types, in proportions reflecting cell type ratios in taste buds (I > II > III). Conclusions Shh+ cells are not stem cells, but are post-mitotic, immediate precursors of taste cells. Shh+ cells differentiate into each of the three taste cell types, and the choice of a specific taste cell fate is regulated to maintain the proper ratio within buds. PMID:24590958

Loss of SYNJ1 dual phosphatase activity leads to early onset refractory seizures and progressive neurological decline

DEFF Research Database (Denmark)

Hardies, Katia; Cai, Yiying; Jardel, Claude

2016-01-01

SYNJ1 encodes a polyphosphoinositide phosphatase, synaptojanin 1, which contains two consecutive phosphatase domains and plays a prominent role in synaptic vesicle dynamics. Autosomal recessive inherited variants in SYNJ1 have previously been associated with two different neurological diseases...... with intractable epilepsy and tau pathology. We performed whole exome or genome sequencing in three independent sib pairs with early onset refractory seizures and progressive neurological decline, and identified novel segregating recessive SYNJ1 defects. A homozygous missense variant resulting in an amino acid...

Control of the mitotic exit network during meiosis

Science.gov (United States)

Attner, Michelle A.; Amon, Angelika

2012-01-01

The mitotic exit network (MEN) is an essential GTPase signaling pathway that triggers exit from mitosis in budding yeast. We show here that during meiosis, the MEN is dispensable for exit from meiosis I but contributes to the timely exit from meiosis II. Consistent with a role for the MEN during meiosis II, we find that the signaling pathway is active only during meiosis II. Our analysis further shows that MEN signaling is modulated during meiosis in several key ways. Whereas binding of MEN components to spindle pole bodies (SPBs) is necessary for MEN signaling during mitosis, during meiosis MEN signaling occurs off SPBs and does not require the SPB recruitment factor Nud1. Furthermore, unlike during mitosis, MEN signaling is controlled through the regulated interaction between the MEN kinase Dbf20 and its activating subunit Mob1. Our data lead to the conclusion that a pathway essential for vegetative growth is largely dispensable for the specialized meiotic divisions and provide insights into how cell cycle regulatory pathways are modulated to accommodate different modes of cell division. PMID:22718910

Mitotic chromosome transmission fidelity mutants in Saccharomyces cerevisiae

International Nuclear Information System (INIS)

Spencer, F.; Gerring, S.L.; Connelly, C.; Hieter, P.

1990-01-01

The authors have isolated 136 independent EMS-induced mutations in haploid yeast strains that exhibit decreased chromosome transmission fidelity in mitosis. Eight-five percent of the mutations are recessive and 15% are partially dominant. Complementation analysis between MATa and MATα isolates identifies 11 chromosome transmission fidelity (CTF) complementation groups, the largest of which is identical to CHL1. For 49 independent mutations, no corresponding allele has been recovered in the opposite mating type. The initial screen monitored the stability of a centromere-linked color marker on a nonessential yeast chromosome fragment; the mitotic inheritance of natural yeast chromosome III is also affected by the ctf mutations. Of the 136 isolates identified, seven were inviable at 37 degree and five were inviable at 11 degree. In all cases tested, these temperature conditional lethalities cosegregated with the chromosome instability phenotype. Five additional complementation groups (ctf12 through ctf16) have been defined by complementation analysis of the mutations causing inviability at 37 degree. All of the mutant strains showed normal sensitivity to ultraviolet and γ-irradiation

Sport and early osteoarthritis: the role of sport in aetiology, progression and treatment of knee osteoarthritis.

Science.gov (United States)

Vannini, F; Spalding, T; Andriolo, L; Berruto, M; Denti, M; Espregueira-Mendes, J; Menetrey, J; Peretti, G M; Seil, R; Filardo, G

2016-06-01

Sports activities are considered favourable for general health; nevertheless, a possible influence of sports practice on the development of early osteoarthritis (OA) is a cause for concern. A higher incidence of OA in knees and ankles of former high-impact sports players than in those of the normal population has been shown and it is still debatable whether the cause is either to be recognized generically in the higher number of injuries or in a joint overload. The possibility to address knee OA in its early phases may be strictly connected to the modification of specific extrinsic or intrinsic factors, related to the patient in order to save the joint from further disease progression; these include sport practice, equipment and load. Non-surgical therapies such as continuative muscles reinforce and training play a strong role in the care of athletes with early OA, particularly if professional. There is an overall agreement on the need of an early restoring of a proper meniscal, ligament and cartilage integrity in order to protect the knee and resume sports safely, whereas alignment is a point still strongly debatable especially for professional athletes. Remaining questions still to be answered are the risks of different sports in relation to one another, although an actual protective effect of low-impact sports, such as walking, swimming or cycling, has been recognized on the appearance or worsening of OA, the effect of continuing or ceasing to practice a sport on the natural history of early OA, and even following appropriate treatment is still unknown.

Distinct pools of cdc25C are phosphorylated on specific TP sites and differentially localized in human mitotic cells.

Directory of Open Access Journals (Sweden)

Celine Franckhauser

Full Text Available BACKGROUND: The dual specificity phosphatase cdc25C was the first human cdc25 family member found to be essential in the activation of cdk1/cyclin B1 that takes place at the entry into mitosis. Human cdc25C is phosphorylated on Proline-dependent SP and TP sites when it becomes active at mitosis and the prevalent model is that this phosphorylation/activation of cdc25C would be part of an amplification loop with cdk1/cyclin B1. METHODOLOGY/PRINCIPAL FINDINGS: Using highly specific antibodies directed against cdc25C phospho-epitopes, pT67 and pT130, we show here that these two phospho-forms of cdc25C represent distinct pools with differential localization during human mitosis. Phosphorylation on T67 occurs from prophase and the cdc25C-pT67 phospho-isoform closely localizes with condensed chromosomes throughout mitosis. The phospho-T130 form of cdc25C arises in late G2 and associates predominantly with centrosomes from prophase to anaphase B where it colocalizes with Plk1. As shown by immunoprecipitation of each isoform, these two phospho-forms are not simultaneously phosphorylated on the other mitotic TP sites or associated with one another. Phospho-T67 cdc25C co-precipitates with MPM2-reactive proteins while pT130-cdc25C is associated with Plk1. Interaction and colocalization of phosphoT130-cdc25C with Plk1 demonstrate in living cells, that the sequence around pT130 acts as a true Polo Box Domain (PBD binding site as previously identified from in vitro peptide screening studies. Overexpression of non-phosphorylatable alanine mutant forms for each isoform, but not wild type cdc25C, strongly impairs mitotic progression showing the functional requirement for each site-specific phosphorylation of cdc25C at mitosis. CONCLUSIONS/SIGNIFICANCE: These results show for the first time that in human mitosis, distinct phospho-isoforms of cdc25C exist with different localizations and interacting partners, thus implying that the long-standing model of a cdc25C

Effect of copper intrauterine device vs. injectable contraceptive on serum hormone levels and cell mitotic activity in endometrium

Directory of Open Access Journals (Sweden)

Ebtesam Moustafa Kamal

2013-09-01

Conclusion: Either copper intrauterine device or injectable contraceptive usage for more than 9 months results in significant decrease in endometrial proliferative or cell mitotic activity. While copper IUD has no effect on serum estradiol or progesterone levels, DMPA usage increased serum progesterone level with no effect on serum estradiol.

Identification of Conserved MEL-28/ELYS Domains with Essential Roles in Nuclear Assembly and Chromosome Segregation.

Science.gov (United States)

Gómez-Saldivar, Georgina; Fernandez, Anita; Hirano, Yasuhiro; Mauro, Michael; Lai, Allison; Ayuso, Cristina; Haraguchi, Tokuko; Hiraoka, Yasushi; Piano, Fabio; Askjaer, Peter

2016-06-01

Nucleoporins are the constituents of nuclear pore complexes (NPCs) and are essential regulators of nucleocytoplasmic transport, gene expression and genome stability. The nucleoporin MEL-28/ELYS plays a critical role in post-mitotic NPC reassembly through recruitment of the NUP107-160 subcomplex, and is required for correct segregation of mitotic chromosomes. Here we present a systematic functional and structural analysis of MEL-28 in C. elegans early development and human ELYS in cultured cells. We have identified functional domains responsible for nuclear envelope and kinetochore localization, chromatin binding, mitotic spindle matrix association and chromosome segregation. Surprisingly, we found that perturbations to MEL-28's conserved AT-hook domain do not affect MEL-28 localization although they disrupt MEL-28 function and delay cell cycle progression in a DNA damage checkpoint-dependent manner. Our analyses also uncover a novel meiotic role of MEL-28. Together, these results show that MEL-28 has conserved structural domains that are essential for its fundamental roles in NPC assembly and chromosome segregation.

[Stability in association of the peripheral material with mitotic chromosomes].

Science.gov (United States)

Kosykh, M I; Chentsov, Iu S

2002-01-01

The localization of nucleolar proteins (fibrillarin and B-23), and of the protein of interphase nuclear matrix (NMP-65) was studied in the perichromosomal material (CM) after of short hypotonic treatment (15% solution of Henks medium) on cultured pig embryonic kidney cells, followed by restoration of isotonic conditions. It is shown that during hypotonic shock the mitotic chromosomes demonstrate reversible swelling, but their periphery is bounded with a rim of PCM, containing antibodies to fibrillarin and NMP-65, but not to B-23. After returning the cells to the initial isotonic medium, all the three proteins can be detected again on the periphery of chromosomes. It suggests the existence of different stability in the association of free proteins with chromosome bodies. Besides, B-23 and fibrillarin could be visualized in residual nucleoli after a complete extraction of histones and DNA from nuclei.

JMJD5 (Jumonji Domain-containing 5) Associates with Spindle Microtubules and Is Required for Proper Mitosis.

Science.gov (United States)

He, Zhimin; Wu, Junyu; Su, Xiaonan; Zhang, Ye; Pan, Lixia; Wei, Huimin; Fang, Qiang; Li, Haitao; Wang, Da-Liang; Sun, Fang-Lin

2016-02-26

Precise mitotic spindle assembly is a guarantee of proper chromosome segregation during mitosis. Chromosome instability caused by disturbed mitosis is one of the major features of various types of cancer. JMJD5 has been reported to be involved in epigenetic regulation of gene expression in the nucleus, but little is known about its function in mitotic process. Here we report the unexpected localization and function of JMJD5 in mitotic progression. JMJD5 partially accumulates on mitotic spindles during mitosis, and depletion of JMJD5 results in significant mitotic arrest, spindle assembly defects, and sustained activation of the spindle assembly checkpoint (SAC). Inactivating SAC can efficiently reverse the mitotic arrest caused by JMJD5 depletion. Moreover, JMJD5 is found to interact with tubulin proteins and associate with microtubules during mitosis. JMJD5-depleted cells show a significant reduction of α-tubulin acetylation level on mitotic spindles and fail to generate enough interkinetochore tension to satisfy the SAC. Further, JMJD5 depletion also increases the susceptibility of HeLa cells to the antimicrotubule agent. Taken together, these results suggest that JMJD5 plays an important role in regulating mitotic progression, probably by modulating the stability of spindle microtubules. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Integrin-Targeted Hybrid Fluorescence Molecular Tomography/X-ray Computed Tomography for Imaging Tumor Progression and Early Response in Non-Small Cell Lung Cancer

Directory of Open Access Journals (Sweden)

Xiaopeng Ma

2017-01-01

Full Text Available Integrins play an important role in tumor progression, invasion and metastasis. Therefore we aimed to evaluate a preclinical imaging approach applying ανβ3 integrin targeted hybrid Fluorescence Molecular Tomography/X-ray Computed Tomography (FMT-XCT for monitoring tumor progression as well as early therapy response in a syngeneic murine Non-Small Cell Lung Cancer (NSCLC model. Lewis Lung Carcinomas were grown orthotopically in C57BL/6 J mice and imaged in-vivo using a ανβ3 targeted near-infrared fluorescence (NIRF probe. ανβ3-targeted FMT-XCT was able to track tumor progression. Cilengitide was able to substantially block the binding of the NIRF probe and suppress the imaging signal. Additionally mice were treated with an established chemotherapy regimen of Cisplatin and Bevacizumab or with a novel MEK inhibitor (Refametinib for 2 weeks. While μCT revealed only a moderate slowdown of tumor growth, ανβ3 dependent signal decreased significantly compared to non-treated mice already at one week post treatment. ανβ3 targeted imaging might therefore become a promising tool for assessment of early therapy response in the future.

Mitotic chromosome loss in a radiation-sensitive strain of the yeast Saccharomyces cerevisiae

International Nuclear Information System (INIS)

Mortimer, R.K.; Contopoulou, R.; Schild, D.

1981-01-01

Cells of Saccharomyces cerevisiae with mutations in the RAD52 gene have previously been shown to be defective in meiotic and mitotic recombination, in sporulation, and in repair of radiation-induced damage to DNA. In this study we show that diploid cells homozygous for rad52 lose chromosomes at high frequencies and that these frequencies of loss can be increased dramatically by exposure of these cells to x-rays. Genetic analyses of survivors of x-ray treatment demonstrate that chromosome loss events result in the conversion of diploid cells to cells with near haploid chromosome numbers

Transient phosphorylation of tumor associated microtubule associated protein (TMAP)/cytoskeleton associated protein 2 (CKAP2) at Thr-596 during early phases of mitosis.

Science.gov (United States)

Hong, Kyung Uk; Choi, Yong-Bock; Lee, Jung-Hwa; Kim, Hyun-Jun; Kwon, Hye-Rim; Seong, Yeon-Sun; Kim, Heung Tae; Park, Joobae; Bae, Chang-Dae; Hong, Kyeong-Man

2008-08-31

Tumor associated microtubule associated protein (TMAP), also known as cytoskeleton associated protein 2 (CKAP2) is a mitotic spindle-associated protein whose expression is cell cycle-regulated and also frequently deregulated in cancer cells. Two monoclonal antibodies (mAbs) against TMAP/CKAP2 were produced: B-1-13 and D-12-3. Interestingly, the reactivity of mAb D-12-3 to TMAP/CKAP2 was markedly decreased specifically in mitotic cell lysate. The epitope mapping study showed that mAb D-12-3 recognizes the amino acid sequence between 569 and 625 and that phosphorylation at T596 completely abolishes the reactivity of the antibody, suggesting that the differential reactivity originates from the phosphorylation status at T596. Immunofluorescence staining showed that mAb D-12-3 fails to detect TMAP/CKAP2 in mitotic cells between prophase and metaphase, but the staining becomes evident again in anaphase, suggesting that phosphorylation at T596 occurs transiently during early phases of mitosis. These results suggest that the cellular functions of TMAP/CKAP2 might be regulated by timely phosphorylation and dephosphorylation during the course of mitosis.

Pretreatment advanced lung cancer inflammation index (ALI) for predicting early progression in nivolumab-treated patients with advanced non-small cell lung cancer.

Science.gov (United States)

Shiroyama, Takayuki; Suzuki, Hidekazu; Tamiya, Motohiro; Tamiya, Akihiro; Tanaka, Ayako; Okamoto, Norio; Nakahama, Kenji; Taniguchi, Yoshihiko; Isa, Shun-Ichi; Inoue, Takako; Imamura, Fumio; Atagi, Shinji; Hirashima, Tomonori

2018-01-01

Programmed death-ligand 1 (PD-L1) expression status is inadequate for indicating nivolumab in patients with non-small cell lung cancer (NSCLC). Because the baseline advanced lung cancer inflammation index (ALI) is reportedly associated with patient outcomes, we investigated whether the pretreatment ALI is prognostic in NSCLC patients treated with nivolumab. We retrospectively reviewed the medical records of all patients treated with nivolumab for advanced NSCLC between December 2015 and May 2016 at three Japanese institutes. Multivariate logistic regression and Cox proportional hazards models were used to assess the impact of the pretreatment ALI (and other inflammation-related parameters) on progression-free survival (PFS) and early progression (i.e., within 8 weeks after starting nivolumab). A total of 201 patients were analyzed; their median age was 68 years (range, 27-87 years), 67% were men, and 24% had an Eastern Cooperative Oncology Group (ECOG) performance status of 2 or higher. An ECOG performance status ≥2, serum albumin ALI ALI ALI was found to be a significant independent predictor of early progression in patients with advanced NSCLC receiving nivolumab, and may help identify patients likely to benefit from continued nivolumab treatment in routine clinical practice. © 2017 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.

Change of mitotic behavior and ultra structure of 'Fuju' (Citrus reticulata Blanco) stem-apex clones after space flight

International Nuclear Information System (INIS)

Wu Rujian; Huang Jinghao; Wen Shouxing; Cai Zijian; Luo Tuyan; Chen Liangfeng; Wang Zhouwen

2011-01-01

By using conventional squash stain technique and ultrathin sectioning technique, the effects of space flight on mitotic behavior and ultrastructure were studied in the shoot apical meristem of 'Fuju' (Citrus reticulata Blanco), which had been carried by China's seed-breeding satellite, Shijian-8. The results showed that space flight had effect on the mutagenesis of stem-apical meristem. Abnormal mitosis with various degrees had been detected in 13 mutant clones, of which mitotic aberrations in clone '08004' were significantly higher than the others. The aberration rate of numerical abnormalities of chromosomes at metaphase, lagging chromosome, micronucleus, C-spindle, S-spindle and polyarch spindle in the clone '08004' was 0.34%, 0.669%, 0.86%, 0.17%, 1.20% and 1.03%, respectively. The ultrastructure of mesophyll cell in most clones was unchanged, but nucleus chromatin agglutination, chloroplast thylakoid disintegrated, autophagosome appeared, cell vacuolated, plasmolysis and the formation of apoptotic body were found in the clone '08004', suggesting that programmed cell death (PCD) Nevertheless, no change in the mitochondrial structure was observed until terminal phase of PCD. (authors)

Radiation induced asymmetries in mitotic recombination: evidence for a directional bias in the formation of asymmetric hybrid DNA in yeast

International Nuclear Information System (INIS)

Friedman, L.R.; Sobell, H.M.

We have examined radiation-induced mitotic recombination using two alleles (his1-36, his1-49) in the his1 gene. When the haploid containing his1-36 is irradiated with varying doses of γ rays and then mated with the unirradiated strain containing his1-49, analyses of the selected prototrophs show them to be primarily + +/+ 49. If, on the other hand, the haploid strain containing his1-49 is the irradiated parent, the prototrophic diploids are primarily + +/36 +. In control experiments, where either both strains are irradiated or not irradiated, no such asymmetries are found. These data indicate that the irradiated haploid chromosome tends to be the recipient of genetic information. We interpret these results as indicating a directional bias in the formation of hybrid DNA in radiation-induced mitotic recombination, and discuss these results in terms of current models of genetic recombination

Influence of the radiation (Co60) in pre-implants rabbit embryos: effect on atypic mitotic index and embryo pole development

International Nuclear Information System (INIS)

Approbato, Mario S.; Oliveira Moura, Katia K.V. de; Souza Florencio, Rodopiano de; Garcia, Ricardo; Faria, Renato S.; Benedetti, Leonardo N.; Goulart, Flamarion B.

1995-01-01

We studied the effect of ionizing irradiation on 12 New Zealand rabbits (65 embryos), at three different times: at match time (zero hour), two days after and four days after, with two different irradiation doses: five c Gy and ten c Gy. Six rabbits (36 blastocysts) were used as controls. the matching instant was the zero hour. Exactly six days after (± 60 minutes) the embryos of each rabbit was picked up by flushing the uterus with culture media. the embryos were fixed in methanol for 48 hours, and colored with acid Mayer hematoxylin. The following embryo parameters were studied: embryo pole development; percentage of abnormal mitotic figures. irradiation time was associated with lower scores of embryo pole development, but not with irradiation dose. There were no gross abnormalities of embryo pole. The abnormal mitotic cells was affected both by the time and dose of irradiation. (author)

Deficient expression of DNA repair enzymes in early progression to sporadic colon cancer

Science.gov (United States)

2012-01-01

Background Cancers often arise within an area of cells (e.g. an epithelial patch) that is predisposed to the development of cancer, i.e. a "field of cancerization" or "field defect." Sporadic colon cancer is characterized by an elevated mutation rate and genomic instability. If a field defect were deficient in DNA repair, DNA damages would tend to escape repair and give rise to carcinogenic mutations. Purpose To determine whether reduced expression of DNA repair proteins Pms2, Ercc1 and Xpf (pairing partner of Ercc1) are early steps in progression to colon cancer. Results Tissue biopsies were taken during colonoscopies of 77 patients at 4 different risk levels for colon cancer, including 19 patients who had never had colonic neoplasia (who served as controls). In addition, 158 tissue samples were taken from tissues near or within colon cancers removed by resection and 16 tissue samples were taken near tubulovillous adenomas (TVAs) removed by resection. 568 triplicate tissue sections (a total of 1,704 tissue sections) from these tissue samples were evaluated by immunohistochemistry for 4 DNA repair proteins. Substantially reduced protein expression of Pms2, Ercc1 and Xpf occurred in field defects of up to 10 cm longitudinally distant from colon cancers or TVAs and within colon cancers. Expression of another DNA repair protein, Ku86, was infrequently reduced in these areas. When Pms2, Ercc1 or Xpf were reduced in protein expression, then either one or both of the other two proteins most often had reduced protein expression as well. The mean inner colon circumferences, from 32 resections, of the ascending, transverse and descending/sigmoid areas were measured as 6.6 cm, 5.8 cm and 6.3 cm, respectively. When combined with other measurements in the literature, this indicates the approximate mean number of colonic crypts in humans is 10 million. Conclusions The substantial deficiencies in protein expression of DNA repair proteins Pms2, Ercc1 and Xpf in about 1 million

X-ray- and TEM-induced mitotic recombination in Drosophila melanogaster: Unequal and sister-strand recombination

International Nuclear Information System (INIS)

Becker, H.J.

1975-01-01

Twin mosaic spots of dark-apricot and light-apricot ommatidia were found in the eyes of wsup(a)/wsup(a) females, of wsup(a) males, of females homozygous for In(1)sc 4 , wsup(a) and of attached-X females homozygous for wsup(a). The flies were raised from larvae which had been treated with 1,630 R of X-rays at the age of 48-52 hours. An additional group of wsup(a)/wsup(a) females and wsup(a) males came from larvae that had been fed with triethylene melamine (TEM) at the age of 22-24 hours. The twin spots apparently were the result of induced unequal mitotic recombination, i.e. from unequal sister-strand recombination in the males and from unequal sister-strand recombination as well as, possibly, unequal recombination between homologous strands in the females. That is, a duplication resulted in wsup(a)Dpwsup(a)/wsup(a) dark-apricto ommatidia and the corresponding deficiency in an adjacent area of wsup(a)/Dfwsup(a) light-apricot ommatidia. In an additional experiment sister-strand mitotic recombination in the ring-X chromosome of ring-X/rod-X females heterozygous for w and wsup(co) is believed to be the cause for X-ray induced single mosaic spots that show the phenotype of the rod-X marker. (orig.) [de

Mitotic and meiotic chromosomes of a southern Brazilian population of Boophilus microplus (Acari, Ixodidae

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Rosane Nunes Garcia

Full Text Available Using conventional staining with acetic orcein and C-banding techniques it was investigated constitutive heterochromatin chromosomal polymorphisms and the mitotic and the meiotic behavior of male and female chromosomes of Boophilus microplus (Canestrini, 1887. Some differences were detected in the population of southern Brazil as compared to the data of other authors for populations in other latitudes. The differences being mainly concerned with the distribution of constitutive centromeric heterochromatin and variation in the length of heterochromatic blocks in the pericentromeric regions of some chromosome pairs.

Discrimination of bromodeoxyuridine labelled and unlabelled mitotic cells in flow cytometric bromodeoxyuridine/DNA analysis

DEFF Research Database (Denmark)

Jensen, P O; Larsen, J K; Christensen, I J

1994-01-01

Bromodeoxyuridine (BrdUrd) labelled and unlabelled mitotic cells, respectively, can be discriminated from interphase cells using a new method, based on immunocytochemical staining of BrdUrd and flow cytometric four-parameter analysis of DNA content, BrdUrd incorporation, and forward and orthogonal...... light scatter. The method was optimized using the human leukemia cell lines HL-60 and K-562. Samples of 10(5) ethanol-fixed cells were treated with pepsin/HCl and stained as a nuclear suspension with anti-BrdUrd antibody, FITC-conjugated secondary antibody, and propidium iodide. Labelled mitoses could...

Serial Derotational Casting in Idiopathic and Non-Idiopathic Progressive Early-Onset Scoliosis.

Science.gov (United States)

Gussous, Yazeed M; Tarima, Sergey; Zhao, Shi; Khan, Safdar; Caudill, Angela; Sturm, Peter; Hammerberg, Kim W

2015-05-01

Serial derotational casting has been used as a definitive treatment or as delaying strategy in progressive idiopathic (IS) and non-idiopathic (NIS) early-onset scoliosis (EOS). Retrospective chart and radiographic review of patients who underwent serial casting for progressive EOS between 2005 and 2012 at a single institution. A total of 74 consecutive patients entered serial cast treatment. Twenty-eight were currently being casted, 30 completed cast treatment and were converted to thoracolumbosacral orthosis (TLSO), 9 were treated surgically, 6 were lost to follow-up, and 1 had no further treatment. The researchers diagnosed IS in 41 patients; 33 had NIS. At presentation the IS group had an average Cobb angle (CA) of 49° and a rib vertebral angle difference (RVAD) of 37°. The NIS group had a CA of 51° (p = .69) and RVAD of 37° (p = .94). In patients currently being casted, 19 IS patients had a decreased CA, from 47° to 27°. The 9 NIS patients had a decreased CA, from 62° to 57° (p = .0002). Cobb angle improvement was significantly better in IS (p = .0005). In the TLSO group the 17 IS patients had a decreased average CA, from 46° to 18°, after serial casting and the 13 NIS patients decreased CA from 42° to 32°. Patients with IS had better improvement in CA than the NIS group (p Casting initiated before age 2 years yielded better curve correction for IS (p casting than NIS patients. Casting in IS patients before age 24 months yielded better curve correction. Patients who required surgery had a higher age and Cobb angle at presentation than those who transitioned to a TLSO. The surgical group was observed for a similar duration of time and there was no significant statistical difference. Although RVAD is a predictor of progression in infantile IS, it did not show a predictive value in the response to casting of either the IS or NIS groups. Copyright © 2015 Scoliosis Research Society. Published by Elsevier Inc. All rights reserved.

Research progress in early diagnosis of Alzheimer's disease

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Meng-sha SUN

2018-04-01

Full Text Available Alzheimer's disease (AD is a kind of central nervous system degenerative disease with higher incidence, which has been paid increasing attention. The pathogenesis is not yet clear though it has been studied a lot. The existing theories focused on amyloid β-protein (Aβ deposit, hyperphosphorylation of tau and cholinergic neuronal loss. There is mainly symptomatic treatment which cannot reverse disease course. So early diagnosis is particularly important for prevention and treatment of AD. The article will review recent advances in the studies of early diagnosis of AD. It may help accurately diagnose the process from mild cognitive impairment (MCI to early AD and give advice on prevention and treatment. DOI: 10.3969/j.issn.1672-6731.2018.03.011

Erratum to: On the Progression and Stability of Adolescent Identity Formation. A Five-Wave Longitudinal Study in Early-to-Middle and Middle-to-Late Adolescence

NARCIS (Netherlands)

Meeus, Wim; van de Schoot, Rens; Keijsers, Loes; Schwartz, S.J.; Branje, Susan

2014-01-01

This article corrects: On the Progression and Stability of Adolescent Identity Formation: A Five-Wave Longitudinal Study in Early-to-Middle and Middle-to-Late Adolescence Vol. 81, Issue 5, 1565–1581,

Early progressive encephalopathy in boys and MECP2 mutations.

Science.gov (United States)

Kankirawatana, P; Leonard, H; Ellaway, C; Scurlock, J; Mansour, A; Makris, C M; Dure, L S; Friez, M; Lane, J; Kiraly-Borri, C; Fabian, V; Davis, M; Jackson, J; Christodoulou, J; Kaufmann, W E; Ravine, D; Percy, A K

2006-07-11

MECP2 mutations mainly occur in females with Rett syndrome. Mutations have been described in 11 boys with progressive encephalopathy: seven of nine with affected sisters and two de novo. The authors report four de novo occurrences: three pathogenic and one potentially pathogenic. Common features include failure to thrive, respiratory insufficiency, microcephaly, and abnormal motor control. MECP2 mutations should be assessed in boys with progressive encephalopathy and one or more of respiratory insufficiency, abnormal movements or tone, and intractable seizures.

Propagation of damage in the rat brain following sarin exposure: Differential progression of early processes

Energy Technology Data Exchange (ETDEWEB)

Lazar, Shlomi; Egoz, Inbal; Brandeis, Rachel; Chapman, Shira; Bloch-Shilderman, Eugenia; Grauer, Ettie, E-mail: ettieg@iibr.gov.il

2016-11-01

Sarin is an irreversible organophosphate cholinesterase inhibitor and a highly toxic warfare agent. Following the overt, dose-dependent signs (e.g. tremor, hyper secretion, seizures, respiratory depression and eventually death), brain damage is often reported. The goal of the present study was to characterize the early histopathological and biochemical events leading to this damage. Rats were exposed to 1LD50 of sarin (80 μg/kg, i.m.). Brains were removed at 1, 2, 6, 24 and 48 h and processed for analysis. Results showed that TSPO (translocator protein) mRNA increased at 6 h post exposure while TSPO receptor density increased only at 24 h. In all brain regions tested, bax mRNA decreased 1 h post exposure followed by an increase 24 h later, with only minor increase in bcl2 mRNA. At this time point a decrease was seen in both anti-apoptotic protein Bcl2 and pro-apoptotic Bax, followed by a time and region specific increase in Bax. An immediate elevation in ERK1/2 activity with no change in JNK may indicate an endogenous “first response” mechanism used to attenuate the forthcoming apoptosis. The time dependent increase in the severity of brain damage included an early bi-phasic activation of astrocytes, a sharp decrease in intact neuronal cells, a time dependent reduction in MAP2 and up to 15% of apoptosis. Thus, neuronal death is mostly due to necrosis and severe astrocytosis. The data suggests that timing of possible treatments should be determined by early events following exposure. For example, the biphasic changes in astrocytes activity indicate a possible beneficial effects of delayed anti-inflammatory intervention. - Highlights: • The severity of brain damage post 1LD50 sarin exposure is time dependent. • Sarin induce differential progression of early processes in the rat brain. • Potential treatments should be timed according to early events following exposure. • The biphasic astrocytes activity suggests a delay in anti-inflammatory intervention.

Propagation of damage in the rat brain following sarin exposure: Differential progression of early processes

International Nuclear Information System (INIS)

Lazar, Shlomi; Egoz, Inbal; Brandeis, Rachel; Chapman, Shira; Bloch-Shilderman, Eugenia; Grauer, Ettie

2016-01-01

Sarin is an irreversible organophosphate cholinesterase inhibitor and a highly toxic warfare agent. Following the overt, dose-dependent signs (e.g. tremor, hyper secretion, seizures, respiratory depression and eventually death), brain damage is often reported. The goal of the present study was to characterize the early histopathological and biochemical events leading to this damage. Rats were exposed to 1LD50 of sarin (80 μg/kg, i.m.). Brains were removed at 1, 2, 6, 24 and 48 h and processed for analysis. Results showed that TSPO (translocator protein) mRNA increased at 6 h post exposure while TSPO receptor density increased only at 24 h. In all brain regions tested, bax mRNA decreased 1 h post exposure followed by an increase 24 h later, with only minor increase in bcl2 mRNA. At this time point a decrease was seen in both anti-apoptotic protein Bcl2 and pro-apoptotic Bax, followed by a time and region specific increase in Bax. An immediate elevation in ERK1/2 activity with no change in JNK may indicate an endogenous “first response” mechanism used to attenuate the forthcoming apoptosis. The time dependent increase in the severity of brain damage included an early bi-phasic activation of astrocytes, a sharp decrease in intact neuronal cells, a time dependent reduction in MAP2 and up to 15% of apoptosis. Thus, neuronal death is mostly due to necrosis and severe astrocytosis. The data suggests that timing of possible treatments should be determined by early events following exposure. For example, the biphasic changes in astrocytes activity indicate a possible beneficial effects of delayed anti-inflammatory intervention. - Highlights: • The severity of brain damage post 1LD50 sarin exposure is time dependent. • Sarin induce differential progression of early processes in the rat brain. • Potential treatments should be timed according to early events following exposure. • The biphasic astrocytes activity suggests a delay in anti-inflammatory intervention.

Early embryonic chromosome instability results in stable mosaic pattern in human tissues.

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Hasmik Mkrtchyan

Full Text Available The discovery of copy number variations (CNV in the human genome opened new perspectives on the study of the genetic causes of inherited disorders and the aetiology of common diseases. Here, a single-cell-level investigation of CNV in different human tissues led us to uncover the phenomenon of mitotically derived genomic mosaicism, which is stable in different cell types of one individual. The CNV mosaic ratios were different between the 10 individuals studied. However, they were stable in the T lymphocytes, immortalized B lymphoblastoid cells, and skin fibroblasts analyzed in each individual. Because these cell types have a common origin in the connective tissues, we suggest that mitotic changes in CNV regions may happen early during embryonic development and occur only once, after which the stable mosaic ratio is maintained throughout the differentiated tissues. This concept is further supported by a unique study of immortalized B lymphoblastoid cell lines obtained with 20 year difference from two subjects. We provide the first evidence of somatic mosaicism for CNV, with stable variation ratios in different cell types of one individual leading to the hypothesis of early embryonic chromosome instability resulting in stable mosaic pattern in human tissues. This concept has the potential to open new perspectives in personalized genetic diagnostics and can explain genetic phenomena like diminished penetrance in autosomal dominant diseases. We propose that further genomic studies should focus on the single-cell level, to better understand the aetiology of aging and diseases mediated by somatic mutations.

Description of load progression and pain response during progressive resistance training early after total hip arthroplasty

DEFF Research Database (Denmark)

Mikkelsen, Lone R; Petersen, Annemette K; Mechlenburg, Inger

2016-01-01

events during the initial four weeks of training. RESULTS: The majority of patients experienced only moderate hip pain during exercise (range in median across exercises and sessions: 5-35 mm Visual Analog Scale) and mild pain at rest (median: 1-18 mm Visual Analog Scale), both of which decreased over...... time ( p training load (67%-166 % across exercises, p training sessions, short term pain response (an increase >20 mm Visual Analog Scale) occurred in 13 patients in 24 training sessions. CONCLUSION: Progressive resistance......OBJECTIVE: To describe a progressive resistance training intervention implemented shortly after total hip arthroplasty, including a detailed description of load progression, pain response and adverse events to the training. DESIGN: Secondary analyses of data from the intervention group...

Protein synthesis rate measured with l-[1-11C]tyrosine positron emission tomography correlates with mitotic activity and MIB-1 antibody-detected proliferation in human soft tissue sarcomas

International Nuclear Information System (INIS)

Plaat, B.; Mastik, M.; Molenaar, W.; Kole, A.; Vaalburg, W.; Hoekstra, H.

1999-01-01

Protein synthesis rate (PSR) can be assessed in vivo using positron emission tomography with l-[1- 11 C]tyrosine (TYR-PET). Biological activity of soft tissue sarcomas (STS) can be measured in vitro by the mitotic rate and number of proliferating cells. In STS the grade of malignancy, in which the mitotic index plays a major role, is considered to be the major standard in predicting biological tumour behaviour. This study was designed to test the validity of TYR-PET in relation to different histopathological features. In 21 patients with untreated STS, the PSR was measured using TYR-PET. The number of mitoses was counted and tumours were graded according to the grading system of Coindre et al. (Cancer 1986; 58:306-309). Proliferative activity was assessed by immunohistological detection of the Ki-67 nuclear antigen using MIB-1 monoclonal antibody. To test the association between the PSR and these tumour parameters, a correlation analysis was performed. A significant (P<0.05) correlation was found between PSR and the Ki-67 proliferation index (R = 0.54), and between PSR and mitotic rate (R = 0.64). There was no correlation between PSR and tumour grade. The present study in malignant soft tissue tumours relates in vivo tumour metabolism as established with TYR-PET to tumour activity measured in vitro and indicates that the non-invasive method of TYR-PET can estimate the mitotic and proliferative activity in STS. (orig.)

Override of the radiation-induced mitotic block in human tumour cells by methylxanthines and its relationship to the potentiation of cytotoxicity

International Nuclear Information System (INIS)

Musk, S.R.R.; Steel, G.G.

1990-01-01

Caffeine, theophylline, theobromine and paraxanthine, were tested for ability to override mitotic block induced by ionizing radiation in the human bladder carcinoma cell line RT112. All were found to partially override the block, at a concentration of 1mM in the order caffeine > theophylline > theobromine = paraxanthine. At a concentration of 1 mM only caffeine was found to potentiate cell killing as well as causing block override; at higher concentrations all had a significant effect on survival but little or no further influence on the degree of block override. It is concluded that override of a mitotic block is not in itself sufficient to cause increased killing when irradiated cells are incubated in the presence of caffeine, and that caffeine exerts its potentiating effect by directly inhibiting repair of damage in DNA or by causing override of radiation-induced inhibition of DNA synthesis. (author)

Override of the radiation-induced mitotic block in human tumour cells by methylxanthines and its relationship to the potentiation of cytotoxicity

Energy Technology Data Exchange (ETDEWEB)

Musk, S.R.R.; Steel, G.G. (Institute of Cancer Research, Sutton (UK). Surrey Branch)

1990-06-01

Caffeine, theophylline, theobromine and paraxanthine, were tested for ability to override mitotic block induced by ionizing radiation in the human bladder carcinoma cell line RT112. All were found to partially override the block, at a concentration of 1mM in the order caffeine > theophylline > theobromine = paraxanthine. At a concentration of 1 mM only caffeine was found to potentiate cell killing as well as causing block override; at higher concentrations all had a significant effect on survival but little or no further influence on the degree of block override. It is concluded that override of a mitotic block is not in itself sufficient to cause increased killing when irradiated cells are incubated in the presence of caffeine, and that caffeine exerts its potentiating effect by directly inhibiting repair of damage in DNA or by causing override of radiation-induced inhibition of DNA synthesis. (author).

Early life exposure to permethrin: a progressive animal model of Parkinson's disease.

Science.gov (United States)

Nasuti, Cinzia; Brunori, Gloria; Eusepi, Piera; Marinelli, Lisa; Ciccocioppo, Roberto; Gabbianelli, Rosita

Oxidative stress, alpha-synuclein changes, mitochondrial complex I defects and dopamine loss, observed in the striatum of rats exposed to the pesticide permethrin in early life, could represent neuropathological hallmarks of Parkinson's disease (PD). Nevertheless, an animal model of PD should also fulfill criteria of face and predictive validities. This study was designed to: 1) verify dopaminergic status in the striatum and substantia nigra pars compacta; 2) recognize non-motor symptoms; 3) investigate the time-course development of motor disabilities; 4) assess L-Dopa effectiveness on motor symptoms in rats previously exposed to permethrin in early life. The permethrin-treated group received 34mg/kg daily of permethrin from postnatal day 6 to 21, whereas the age-matched control group was administered with the vehicle only. At adolescent age, the permethrin-treated group showed decreased levels of dopamine in the striatum, loss of dopaminergic neurons in the substantia nigra pars compacta and cognitive impairments. Motor coordination defects appeared at adult age (150days old) in permethrin-treated rats on rotarod and beam walking tasks, whereas no differences between the treated and control groups were detected on the foot print task. Predictive validity was evaluated by testing the ability of L-Dopa (5, 10 or 15mg/kg, os) to restore the postural instability in permethrin-treated rats (150days old) tested in a beam walking task. The results revealed full reversal of motor deficits starting from 10mg/kg of L-Dopa. The overall results indicate that this animal model replicates the progressive, time-dependent nature of the neurodegenerative process in Parkinson's disease. Copyright © 2016 Elsevier Inc. All rights reserved.

On the Progression and Stability of Adolescent Identity Formation : A Five-Wave Longitudinal Study in Early-to-Middle and Middle-to-Late Adolescence

NARCIS (Netherlands)

Meeus, W.H.J.|info:eu-repo/dai/nl/070442215; Van de Schoot, R.|info:eu-repo/dai/nl/304833207; Keijsers, L.|info:eu-repo/dai/nl/304836206; Schwartz, S.; Branje, S.J.T.|info:eu-repo/dai/nl/192657860

2010-01-01

This study examined identity development in a 5-wave study of 923 early-to-middle and 390 middle-to-late adolescents thereby covering the ages of 12–20. Systematic evidence for identity progression was found: The number of diffusions, moratoriums, and searching moratoriums (a newly obtained status)

Cremophor EL stimulates mitotic recombination in uvsH//uvsH diploid strain of Aspergillus nidulans

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Cleverson Busso

2004-03-01

Full Text Available Cremophor EL is a solubilizer and emulsifier agent used in the pharmaceutical and foodstuff industries. The solvent is the principal constituent of paclitaxel's clinical formulation vehicle. Since mitotic recombination plays a crucial role in multistep carcinogenesis, the study of the recombinagenic potential of chemical compounds is of the utmost importance. In our research genotoxicity of cremophor EL has been studied by using an uvsH//uvsH diploid strain of Aspergillus nidulans. Since it spends a great part of its cell cycle in the G2period, this fungus is a special screening system for the study of mitotic recombination induced by chemical substances. Homozygotization Indexes (HI for paba and bi markers from heterozygous B211//A837 diploid strain were determined for the evaluation of the recombinagenic effect of cremophor EL. It has been shown that cremophor EL induces increase in mitotic crossing-over events at nontoxic concentrations (0.05 and 0.075% v/v.Cremofor EL (CEL é um solubilizante e emulsificante amplamente utilizado nas indústrias farmacêuticas e de gêneros alimentícios. É o principal veículo empregado nas formulações clínicas do antineoplásico paclitaxel. Considerando-se que a recombinação mitótica desempenha importante função no processo de carcinogênese, o estudo de substâncias químicas com potencial recombinagênico assume importância crucial, no sentido de se detectar aquelas que eventualmente possam atuar como promotoras de neoplasias. A genotoxicidade do cremofor EL foi estudada no presente trabalho, utilizando-se uma linhagem diplóide uvsH//uvsH de Aspergillus nidulans. Neste fungo as células vegetativas comumente repousam no período G2 do ciclo celular, facilitando a ocorrência da recombinação mitótica. O efeito recombinagênico do CEL foi avaliado através da determinação dos Índices de Homozigotização para os marcadores nutricionais paba e bi do diplóide heterozigoto B211//A837. Os

Inducible nucleotide excision repair (NER) of UV-induced cyclobutane pyrimidine dimers in the cell cycle of the budding yeast Saccharomyces cerevisiae: evidence that inducible NER is confined to the G1 phase of the mitotic cell cycle

International Nuclear Information System (INIS)

Scott, A.D.; Waters, R.

1997-01-01

We previously reported on an inducible component of nucleotide excision repair in Saccharomyces cerevisiae that is controlled by the RAD16 gene. Here we describe a study of this event at the MAT alpha and HML alpha mating-type loci and on the transcribed (TS) and nontranscribed (NTS) strands of the RAD16 gene. Events were examined at various stages of the mitotic cycle in cells synchronised by centrifugal elutriation. Repair of cyclobutane pyrimidine dimers (CPDs) following a single UV dose does not vary significantly in different stages of the mitotic cell cycle. CPDs are removed more rapidly from the transcriptionally active MAT alpha locus than from the silent HML alpha locus, and the TS of RAD16 is repaired faster than the NTS in all stages of the cycle following a single UV irradiation. Enhanced excision of CPDs at MAT alpha and HML alpha can be induced only in the G1 and early S stages of the cell cycle. Here prior irradiation of cells with 25 J/m 2 enhances the removal of CPDs following a second UV dose of 70 J/m 2 . The level of enhancement of repair does not differ significantly between MAT alpha and HML alpha in G1. Enhanced removal of CPDs is absent when cells receive the inducing dose in late S or G2/M. Repair of CPDs in both strands of RAD16 is similarly enhanced only if cells receive the initial irradiation in G1 and early S. The level of enhanced removal of CPDs is not significantly different in the TS and NTS of RAD16 either in asynchronous cells or in cells preirradiated in G1 and early S. It has been shown by others that UV-induced expression of RAD16 remains at high levels if cells are held in G1 by treatment with alpha factor. Therefore the increase in RAD16 transcript levels in G1 may be responsible for the ability to enhance NER solely in this stage of the cell cycle

[Intragenic mitotic recombination induced by ultraviolet and gamma rays in radiosensitive mutants of Saccharomyces cerevisiae yeasts].

Science.gov (United States)

Zakharov, I A; Kasinova, G V; Koval'tsova, S V

1983-01-01

The effect of UV- and gamma-irradiation on the survival and intragenic mitotic recombination (gene conversion) of 5 radiosensitive mutants was studied in comparison with the wild type. The level of spontaneous conversion was similar for RAD, rad2 and rad15, mutations xrs2 and xrs4 increasing and rad54 significantly decreasing it. The frequency of conversion induced by UV-light was greater in rad2, rad15 and xrs2 mutants and lower in xrs4, as compared to RAD. Gamma-irradiation caused induction of gene conversion with an equal frequency in RAD, rad2, rad15. Xrs2 and xrs4 mutations slightly decreased gamma-induced conversion. In rad54 mutant, UV-and gamma-induced conversion was practically absent. In the wild type yeast, a diploid strain is more resistant than a haploid, whereas in rad54 a diploid strain has the same or an increased sensitivity, as compared to a haploid strain (the "inverse ploidy effect"). This effect and also the block of induced mitotic recombination caused by rad54 indicate the presence in the yeast Saccharomyces cerevisiae of repair pathways of UV- and gamma-induced damages acting in diploid cells and realised by recombination. The data obtained as a result of many years' investigation of genetic effects in radiosensitive mutants of yeast are summarised and considered.

The fidelity of synaptonemal complex assembly is regulated by a signaling mechanism that controls early meiotic progression.

Science.gov (United States)

Silva, Nicola; Ferrandiz, Nuria; Barroso, Consuelo; Tognetti, Silvia; Lightfoot, James; Telecan, Oana; Encheva, Vesela; Faull, Peter; Hanni, Simon; Furger, Andre; Snijders, Ambrosius P; Speck, Christian; Martinez-Perez, Enrique

2014-11-24

Proper chromosome segregation during meiosis requires the assembly of the synaptonemal complex (SC) between homologous chromosomes. However, the SC structure itself is indifferent to homology, and poorly understood mechanisms that depend on conserved HORMA-domain proteins prevent ectopic SC assembly. Although HORMA-domain proteins are thought to regulate SC assembly as intrinsic components of meiotic chromosomes, here we uncover a key role for nuclear soluble HORMA-domain protein HTP-1 in the quality control of SC assembly. We show that a mutant form of HTP-1 impaired in chromosome loading provides functionality of an HTP-1-dependent checkpoint that delays exit from homology search-competent stages until all homolog pairs are linked by the SC. Bypassing of this regulatory mechanism results in premature meiotic progression and licensing of homology-independent SC assembly. These findings identify nuclear soluble HTP-1 as a regulator of early meiotic progression, suggesting parallels with the mode of action of Mad2 in the spindle assembly checkpoint. Copyright © 2014 Elsevier Inc. All rights reserved.

Identification of probable early-onset biomarkers for tuberculosis disease progression.

Directory of Open Access Journals (Sweden)

Jayne S Sutherland

Full Text Available Determining what constitutes protective immunity to TB is critical for the development of improved diagnostics and vaccines. The comparison of the immune system between contacts of TB patients, who later develop TB disease (progressors, versus contacts who remain healthy (non-progressors, allows for identification of predictive markers of TB disease. This study provides the first comprehensive analysis of the immune system of progressors and non-progressors using a well-characterised TB case-contact (TBCC platform in The Gambia, West Africa. 22 progressors and 31 non-progressors were analysed at recruitment, 3 months and 18 months (time to progression: median[IQR] of 507[187-714] days. Immunophenotyping of PBMC, plasma cytokine levels and RT-MLPA analysis of whole blood-derived RNA was performed to capture key immune system parameters. At recruitment, progressors had lower PBMC proportions of CD4+ T cells, NKT cells and B cells relative to non-progressors. Analysis of the plasma showed higher levels of IL-18 in progressors compared to non-progressors and analysis of the RNA showed significantly lower gene expression of Bcl2 but higher CCR7 in progressors compared to non-progressors. This study shows several markers that may predict the onset of active TB at a very early stage after infection. Once these markers have been validated in larger studies, they provide avenues to prospectively identify people at risk of developing TB, a key issue in the testing of new TB vaccines.

Extending the Range of a BEV - Early Progress

Energy Technology Data Exchange (ETDEWEB)

Meyer, John; Agathocleous, Nicos; Kang, SH; Vespa, Tony

2015-09-30

The 2015 BEV Kia Soul is available with either a Positive Temperature Coefficient (PTC) heater only or an air-source R134a heat pump with PTC heater combination. Hanon, HATCI, and NREL are jointly, with financial support from the DoE, working towards extending the driving range of the heat pump vehicle. This presentation will focus on the early findings of the project, including test data of the baseline vehicle, early data from a modified vehicle, and range extension goals of the project.

Protein synthesis rate measured with l-[1-{sup 11}C]tyrosine positron emission tomography correlates with mitotic activity and MIB-1 antibody-detected proliferation in human soft tissue sarcomas

Energy Technology Data Exchange (ETDEWEB)

Plaat, B.; Mastik, M.; Molenaar, W. [Department of Pathology, University Hospital Groningen (Netherlands); Kole, A.; Vaalburg, W. [PET Centre, University Hospital Groningen (Netherlands); Hoekstra, H. [Department of Surgical Oncology, University Hospital Groningen (Netherlands)

1999-04-29

Protein synthesis rate (PSR) can be assessed in vivo using positron emission tomography with l-[1-{sup 11}C]tyrosine (TYR-PET). Biological activity of soft tissue sarcomas (STS) can be measured in vitro by the mitotic rate and number of proliferating cells. In STS the grade of malignancy, in which the mitotic index plays a major role, is considered to be the major standard in predicting biological tumour behaviour. This study was designed to test the validity of TYR-PET in relation to different histopathological features. In 21 patients with untreated STS, the PSR was measured using TYR-PET. The number of mitoses was counted and tumours were graded according to the grading system of Coindre et al. (Cancer 1986; 58:306-309). Proliferative activity was assessed by immunohistological detection of the Ki-67 nuclear antigen using MIB-1 monoclonal antibody. To test the association between the PSR and these tumour parameters, a correlation analysis was performed. A significant (P<0.05) correlation was found between PSR and the Ki-67 proliferation index (R = 0.54), and between PSR and mitotic rate (R = 0.64). There was no correlation between PSR and tumour grade. The present study in malignant soft tissue tumours relates in vivo tumour metabolism as established with TYR-PET to tumour activity measured in vitro and indicates that the non-invasive method of TYR-PET can estimate the mitotic and proliferative activity in STS. (orig.) With 2 figs., 2 tabs., 30 refs.

Structure of a Blinkin-BUBR1 complex reveals an interaction crucial for kinetochore-mitotic checkpoint regulation via an unanticipated binding Site

DEFF Research Database (Denmark)

Bolanos-Garcia, Victor M; Lischetti, Tiziana; Matak-Vinković, Dijana

2011-01-01

The maintenance of genomic stability relies on the spindle assembly checkpoint (SAC), which ensures accurate chromosome segregation by delaying the onset of anaphase until all chromosomes are properly bioriented and attached to the mitotic spindle. BUB1 and BUBR1 kinases are central for this proc...

Genetical control of mitotic crossing over in yeast

International Nuclear Information System (INIS)

Fedorova, I.V.; Marfin, A.B.

1982-01-01

Lethal effect of 8 methoxypsoralen (8-MOP) and long-wave ultraviolet radiation (LUR) on diploid and haploid radiosensitive strains of yeast LSaccharomyces cerevisiae has been studied. It is shown that wild type diploids and homozygous with respect to locus rad 2 is considerably more stable than corresponding haploids, while diploid homozygous with respect to rad 54 locus is more sensitive than haploid. Use of the method of repeated irradiation permitted to study capability of radiosensitive diploids to remove 8 MOP-induced DNA photodamages-monoadducts. This process proceeds effectively in the wild type strain and rad 54 rad 54 diploid and was absent in rad 2 rad 2 diploid. Very strong recombinogenous effect of 8-MOP and LUR was discovered when studying mitotic segregation and crossing-over. It is also shown that rad 2 mutation increases slightly and rad 54 mutation decreases sharply frequency of recombination events in yeast cells. It is established by means of the repeated irradiation method that the main contribution to the 8 MOP and LUR recombinogenous effect is made with DNA sutures induced with these agents. Possible participation of different repair systems in the recombination processes induced with 8 MOP and LUR in yeast cells is discussed

Measuring cell cycle progression kinetics with metabolic labeling and flow cytometry.

Science.gov (United States)

Fleisig, Helen; Wong, Judy

2012-05-22

Precise control of the initiation and subsequent progression through the various phases of the cell cycle are of paramount importance in proliferating cells. Cell cycle division is an integral part of growth and reproduction and deregulation of key cell cycle components have been implicated in the precipitating events of carcinogenesis. Molecular agents in anti-cancer therapies frequently target biological pathways responsible for the regulation and coordination of cell cycle division. Although cell cycle kinetics tend to vary according to cell type, the distribution of cells amongst the four stages of the cell cycle is rather consistent within a particular cell line due to the consistent pattern of mitogen and growth factor expression. Genotoxic events and other cellular stressors can result in a temporary block of cell cycle progression, resulting in arrest or a temporary pause in a particular cell cycle phase to allow for instigation of the appropriate response mechanism. The ability to experimentally observe the behavior of a cell population with reference to their cell cycle progression stage is an important advance in cell biology. Common procedures such as mitotic shake off, differential centrifugation or flow cytometry-based sorting are used to isolate cells at specific stages of the cell cycle. These fractionated, cell cycle phase-enriched populations are then subjected to experimental treatments. Yield, purity and viability of the separated fractions can often be compromised using these physical separation methods. As well, the time lapse between separation of the cell populations and the start of experimental treatment, whereby the fractionated cells can progress from the selected cell cycle stage, can pose significant challenges in the successful implementation and interpretation of these experiments. Other approaches to study cell cycle stages include the use of chemicals to synchronize cells. Treatment of cells with chemical inhibitors of key

Comprehensive Identification of SUMO2/3 Targets and Their Dynamics during Mitosis

DEFF Research Database (Denmark)

Schou, Julie; Kelstrup, Christian D; Hayward, Daniel G

2014-01-01

During mitosis large alterations in cellular structures occur rapidly, which to a large extent is regulated by post-translational modification of proteins. Modification of proteins with the small ubiquitin-related protein SUMO2/3 regulates mitotic progression, but few mitotic targets have been...... identified so far. To deepen our understanding of SUMO2/3 during this window of the cell cycle, we undertook a comprehensive proteomic characterization of SUMO2/3 modified proteins in mitosis and upon mitotic exit. We developed an efficient tandem affinity purification strategy of SUMO2/3 modified proteins...... from mitotic cells. Combining this purification strategy with cell synchronization procedures and quantitative mass spectrometry allowed for the mapping of numerous novel targets and their dynamics as cells progressed out of mitosis. This identified RhoGDIα as a major SUMO2/3 modified protein...

Effect of 2,4-D and isoproturon on chromosomal disturbances during mitotic division in root tip cells of Triticum aestivum L.

Science.gov (United States)

Kumar, Sanjay

2010-01-01

The widespread use of the herbicides for weed control and crop productivity in modern agriculture exert a threat on economically important crops by way of cytological damage to the cells of the crop plant or side effects, if any, induced by the herbicides. In the present communication, author describes the effects of 2,4-D and Isoproturon on chromosomal morphology in mitotic cells of Triticum aestivum L. The wheat seedlings were treated with range of concentrations (50-1200 ppm) of 2,4-D and Isoproturon for 72 h at room temperature. In the mitotic cells, twelve distinct chromosome structure abnormalities were observed over control. The observed irregularities were stickiness, c-mitosis, multipolar chromosomes with or without spindles, fragments and bridges, lagging chromosomes, unequal distribution of chromosomes, over contracted chromosomes, unoriented chromosomes, star shaped arrangement of the chromosomes, increased cell size and failure of cell plate formation. The abnormalities like stickiness, fragments, bridges, lagging or dysjunction, unequal distribution and over contracted chromosomes meet frequently.

Abrupt onset of mutations in a developmentally regulated gene during terminal differentiation of post-mitotic photoreceptor neurons in mice.

Directory of Open Access Journals (Sweden)

Ivette M Sandoval

Full Text Available For sensitive detection of rare gene repair events in terminally differentiated photoreceptors, we generated a knockin mouse model by replacing one mouse rhodopsin allele with a form of the human rhodopsin gene that causes a severe, early-onset form of retinitis pigmentosa. The human gene contains a premature stop codon at position 344 (Q344X, cDNA encoding the enhanced green fluorescent protein (EGFP at its 3' end, and a modified 5' untranslated region to reduce translation rate so that the mutant protein does not induce retinal degeneration. Mutations that eliminate the stop codon express a human rhodopsin-EGFP fusion protein (hRho-GFP, which can be readily detected by fluorescence microscopy. Spontaneous mutations were observed at a frequency of about one per retina; in every case, they gave rise to single fluorescent rod cells, indicating that each mutation occurred during or after the last mitotic division. Additionally, the number of fluorescent rods did not increase with age, suggesting that the rhodopsin gene in mature rod cells is less sensitive to mutation than it is in developing rods. Thus, there is a brief developmental window, coinciding with the transcriptional activation of the rhodopsin locus, in which somatic mutations of the rhodopsin gene abruptly begin to appear.

Radiographic assessment of disease progression in rheumatoid arthritis patients undergoing early disease-modifying anti-rheumatic drug treatment

International Nuclear Information System (INIS)

Wick, M.C.

2002-04-01

Rheumatoid arthritis (RA) is a common systemic disease predominantly involving the joints. Since the pathogenesis, etiology and pathophysiological mechanisms of RA have only been partially elucidated, a definitive therapy has not been established. Precise diagnosis and follow-up therapy requires objective quantification, and radiological analyses are considered to be the most appropriate method. The aim of this study was to retrospectively determine the time-dependent progression of joint damage in patients with pharmacologically-treated RA, and to determine which therapeutic agents demonstrate the highest efficacy. Outpatient records, laboratory values, therapy schemes and radiographs from hands and feet of 150 RA patients were collected, analyzed and statistically evaluated. Radiographs were quantified using the Larsen score and supportively using the 'RheumaCoach-Rheumatology' computer software. Our observations reveal that radiologically-detectable damage is most pronounced during the first year of disease, while mitigated and generally progressing linearly thereafter. Overall Larsen scores linearly increased from year 0 to 10 (r=0.853), during which the mean Larsen score increased 7.93 ± 0.76 per year. During the first year, RA progression was similar regardless of the medication administered (gold-compounds, AU; chloroquine, CQ; methotrexate, MTX; sulfasalazine SSZ). While MTX and CQ treatment showed no difference when examined as mean 5-year increment of Larsen score, AU and SSZ showed up to 3 fold higher RA progression compared with MTX. The Larsen score in year 1 did not correlate with that of years 2 to 5. In contrast, Larsen scores in year 2 were linearly related to each of the subsequent 3 years. Despite similar ESR values in various medication groups, cumulative ESR correlated with RA progression, and its reduction with therapeutic efficacy. In conclusion, this study found that, (i) early DMARD-treated RA progressed more rapidly during the first than

The 3' untranslated region of the cyclin B mRNA is not sufficient to enhance the synthesis of cyclin B during a mitotic block in human cells.

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Dominik Schnerch

Full Text Available Antimitotic agents are frequently used to treat solid tumors and hematologic malignancies. However, one major limitation of antimitotic approaches is mitotic slippage, which is driven by slow degradation of cyclin B during a mitotic block. The extent to which cyclin B levels decline is proposed to be governed by an equilibrium between cyclin B synthesis and degradation. It was recently shown that the 3' untranslated region (UTR of the murine cyclin B mRNA contributes to the synthesis of cyclin B during mitosis in murine cells. Using a novel live-cell imaging-based technique allowing us to study synthesis and degradation of cyclin B simultaneously at the single cell level, we tested here the role of the human cyclin B 3'UTR in regulating cyclin B synthesis during mitosis in human cells. We observed that the cyclin B 3'UTR was not sufficient to enhance cyclin B synthesis in human U2Os, HeLa or hTERT RPE-1 cells. A better understanding of how the equilibrium of cyclin B is regulated in mitosis may contribute to the development of improved therapeutic approaches to prevent mitotic slippage in cancer cells treated with antimitotic agents.

Induction of high mitotic index in Petunia suspension cultures by sequential treatment with aphidicolin and colchicine.

Science.gov (United States)

Guri, A; Zelcer, A; Izhar, S

1984-12-01

Significantly higher than normal mitotic index (MI) values were induced in Petunia cell suspensions following treatments with colchicine, aphidicolin, drastic medium replacement, or a sequential application of aphidicolin and colchicine. This last treatment yielded the highest MI values: cells incubated with 30 μg/ml aphidicolin for 18 h, then cultured in drug-free medium for 8 h and finally exposed to 0.1% colchicine for 8 additional hours exhibited MI of 62.8% and 65.7% respectively, for the two cell lines in study.

Progress in rheumatology in the early 21st century

Directory of Open Access Journals (Sweden)

E. L. Nasonov

2014-01-01

Full Text Available Rheumatoid arthritis (RA, juvenile arthritis, spondyloarthritis, including psoriatic arthritis, systemic lupus erythematosus (SLE, and other systemic connective tissue diseases, are the most severe chronic immunoinflammatory rheumatic diseases (IIRDs that affect as high as 10% of the population. Substantial progress has been made in the treatment of IIRDs in the 21st century. The current Treat to Target (T2T strategy for RA is to achieve remission as soon as possible. The main treatment goal is to improve quality of life, by controlling the symptoms of the disease, by preventing joint destruction and dysfunction, and by maintaining social possibilities. The most important way to achieve this goal is to inhibit inflammation and to evaluate the efficiency of treatment, by using the standardized activity indices and by choosing the appropriate treatment option. The widespread use of biological agents in combination with standard disease-modifying antirheumatic drugs could substantially enhance therapeutic effectiveness. A new class of medicaments (chemically synthesized small molecular weight agents to treat RA has appeared. The point of their application is tyrosine kinases, primarily Janus kinase (JAK. The new era in the treatment of SLE and other IIRDs is associated with the design of the new class of drugs Р BLyS inhibitors. In the coming years, the main lines of researches by Russian rheumatologists will be to elaborate a strategy to prevent IIRDs; to introduce innovative methods for their early diagnosis and treatment (biological agents, JAK inhibitors, and other cell signaling molecules and for the prediction of the outcomes of the most severe forms of IIRD; to realize the concept of personified medicine (to investigate the prognostic biomarkers of the efficiency and safety of targeted therapy, to reduce the risk of infectious complications, cardiovascular diseases, cancer, osteoporotic fractures, and other comorbidities.

3'-Deoxy-3'-18F-fluorothymidine positron emission tomography as an early predictor of disease progression in patients with advanced and metastatic pancreatic cancer

International Nuclear Information System (INIS)

Challapalli, Amarnath; Barwick, Tara; Merchant, Shairoz; Pearson, Rachel A.; Howell, Elizabeth C.; Maxwell, Ross J.; Mauri, Francesco; Sumpter, Katherine; Aboagye, Eric O.; Sharma, Rohini

2015-01-01

3'-Deoxy-3'- 18 F-fluorothymidine (FLT) positron emission tomography (PET) has limited utility in abdominal imaging due to high physiological hepatic uptake of tracer. We evaluated FLT PET/CT combined with a temporal-intensity information-based voxel-clustering approach termed kinetic spatial filtering (FLT PET/CT KSF ) for early prediction of response and survival outcomes in locally advanced and metastatic pancreatic cancer patients receiving gemcitabine-based chemotherapy. Dynamic FLT PET/CT data were collected before and 3 weeks after the first cycle of chemotherapy. Changes in tumour FLT PET/CT variables were determined. The primary end point was RECIST 1.1 response on contrast-enhanced CT after 3 months of therapy. Twenty patients were included. Visual distinction between tumours and normal pancreas was seen in FLT PET KSF images. All target lesions (>2 cm), including all primary pancreatic tumours, were visualised. Of the 11 liver metastases, 3 (<2 cm) were not visible after kinetic filtering. Of the 20 patients, 7 progressed (35 %). Maximum standardised uptake value at 60 min post-injection (SUV 60,max ) significantly increased in patients with disease progression (p = 0.04). Receiver-operating characteristic curve analysis indicated that a threshold of SUV 60,max increase of ≥ 12 % resulted in sensitivity, specificity and positive predictive value (PPV) of 71, 100 and 100 %, respectively [area under the curve (AUC) 0.90, p = 0.0001], to predict patients with disease progression. Changes in SUV 60,max were not predictive of survival. FLT PET/CT detected changes in proliferation, with early increase in SUV 60,max predicting progressive disease with a high specificity and PPV. Therefore, FLT PET/CT could be used as an early response biomarker for gemcitabine-based chemotherapy, to select a poor prognostic group who may benefit from novel therapeutic agents in advanced and metastatic pancreatic cancer. (orig.)

Maintaining Genome Stability in Defiance of Mitotic DNA Damage

Science.gov (United States)

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

Phosphorylation and disassembly of intermediate filaments in mitotic cells

International Nuclear Information System (INIS)

Chou, Yinghao; Rosevear, E.; Goldman, R.D.

1989-01-01

As baby hamster kidney (BHK-21) cells enter mitosis, networks of intermediate filaments (IFs) are transformed into cytoplasmic aggregates of protofilaments. Coincident with this morphological change, the phosphate content of vimentin increases from 0.3 mol of P i per mol of protein in interphase to 1.9 mol of P i per mol of protein in mitosis. A similar increase in phosphate content is observed with desmin, from 0.5 mol of P i per mol of protein to 1.5 mol of P i per mol of protein. Fractionation of mitotic cell lysates by hydroxylapatite column chromatography reveals the presence of two IF protein kinase activities, designated as IF protein kinase I and IF protein kinase II. Comparison of two-dimensional 32 P-labeled phosphopeptide maps of vimentin and desmin phosphorylated in vivo in mitosis, and in vitro using partially purified kinase fractions, reveals extensive similarity in the two sets of phosphorylation sites. Phosphorylation of in vitro polymerized IFs by IF protein kinase II induces complete disassembly as determined by negative-stain electron microscopy. The results support the idea that the disassembly of IFs in mitosis is regulated by the phosphorylation of its subunit proteins

Warts phosphorylates mud to promote pins-mediated mitotic spindle orientation in Drosophila, independent of Yorkie.

Science.gov (United States)

Dewey, Evan B; Sanchez, Desiree; Johnston, Christopher A

2015-11-02

Multicellular animals have evolved conserved signaling pathways that translate cell polarity cues into mitotic spindle positioning to control the orientation of cell division within complex tissue structures. These oriented cell divisions are essential for the development of cell diversity and the maintenance of tissue homeostasis. Despite intense efforts, the molecular mechanisms that control spindle orientation remain incompletely defined. Here, we describe a role for the Hippo (Hpo) kinase complex in promoting Partner of Inscuteable (Pins)-mediated spindle orientation. Knockdown of Hpo, Salvador (Sav), or Warts (Wts) each result in a partial loss of spindle orientation, a phenotype previously described following loss of the Pins-binding protein Mushroom body defect (Mud). Similar to orthologs spanning yeast to mammals, Wts kinase localizes to mitotic spindle poles, a prominent site of Mud localization. Wts directly phosphorylates Mud in vitro within its C-terminal coiled-coil domain. This Mud coiled-coil domain directly binds the adjacent Pins-binding domain to dampen the Pins/Mud interaction, and Wts-mediated phosphorylation uncouples this intramolecular Mud interaction. Loss of Wts prevents cortical Pins/Mud association without affecting Mud accumulation at spindle poles, suggesting phosphorylation acts as a molecular switch to specifically activate cortical Mud function. Finally, loss of Wts in Drosophila imaginal disc epithelial cells results in diminished cortical Mud and defective planar spindle orientation. Our results provide new insights into the molecular basis for dynamic regulation of the cortical Pins/Mud spindle positioning complex and highlight a novel link with an essential, evolutionarily conserved cell proliferation pathway. Copyright © 2015 Elsevier Ltd. All rights reserved.

cAMP Signaling Regulates Histone H3 Phosphorylation and Mitotic Entry Through a Disruption of G2 Progression

OpenAIRE

Rodriguez-Collazo, Pedro; Snyder, Sara K.; Chiffer, Rebecca C.; Bressler, Erin A.; Voss, Ty C.; Anderson, Eric P.; Genieser, Hans-Gottfried; Smith, Catharine L.

2008-01-01

cAMP signaling is known to have significant effects on cell growth, either inhibitory or stimulatory depending on the cell type. Study of cAMP-induced growth inhibition in mammalian somatic cells has focused mainly on the combined role of protein kinase A (PKA) and mitogen-activated protein (MAP) kinases in regulation of progression through the G1 phase of the cell cycle. Here we show that cAMP signaling regulates histone H3 phosphorylation in a cell cycle-dependent fashion, increasing it in ...

Factors influencing career progress for early stage clinician-scientists in emerging Asian academic medical centres: a qualitative study in Singapore

Science.gov (United States)

Yoon, Sungwon; Koh, Woon-Puay; Ong, Marcus E H; Thumboo, Julian

2018-01-01

Objectives To explore the factors that influence career progress for early stage clinician-scientists and to identify ways to mitigate these factors in the context of emerging Asian academic medical centres (AMCs). Design Qualitative interviews and thematic data analysis based on grounded theory. Setting and participants Five focus group interviews comprising 29 early career clinician-scientists who have received their first national-level career development award in Singapore. Results Clinical priorities represented an overarching concern with many reporting the difficulty in delineating responsibilities between clinical care and research. Additionally, there was a prevailing perception of the lack of support for research at the institutional level. Participants tended to identify mentors through their own efforts in a relatively haphazard manner, often owing to the dearth of role models and perceived inadequacy of reward systems for mentoring. Support from mentors was thought to be limited in terms of targeted scientific guidance and long-term commitments to the relationship. Most of the participants expressed concerns about how they could secure the next level of funding with diminishing confidence. Notably, the work-life balance was neither conceptualised as a ‘barrier’ to successful pursuit of research career nor was it translated into the reason for leaving the dual clinical-research career pathway. Conclusions Results revealed specific limitations presented by the research environment in newly emerging Asian AMCs. To retain a vibrant clinician-scientist workforce, additional measures are needed, aiming to improve institutional culture of research, build mentoring networks, adopt effective tools for tracking career progress and provide a clear and viable career progression path for clinician-scientist. Further research might explore the cross-cultural differences in managing work-life balance in academic medicine. PMID:29502093

Factors influencing career progress for early stage clinician-scientists in emerging Asian academic medical centres: a qualitative study in Singapore.

Science.gov (United States)

Yoon, Sungwon; Koh, Woon-Puay; Ong, Marcus E H; Thumboo, Julian

2018-03-03

To explore the factors that influence career progress for early stage clinician-scientists and to identify ways to mitigate these factors in the context of emerging Asian academic medical centres (AMCs). Qualitative interviews and thematic data analysis based on grounded theory. Five focus group interviews comprising 29 early career clinician-scientists who have received their first national-level career development award in Singapore. Clinical priorities represented an overarching concern with many reporting the difficulty in delineating responsibilities between clinical care and research. Additionally, there was a prevailing perception of the lack of support for research at the institutional level. Participants tended to identify mentors through their own efforts in a relatively haphazard manner, often owing to the dearth of role models and perceived inadequacy of reward systems for mentoring. Support from mentors was thought to be limited in terms of targeted scientific guidance and long-term commitments to the relationship. Most of the participants expressed concerns about how they could secure the next level of funding with diminishing confidence. Notably, the work-life balance was neither conceptualised as a 'barrier' to successful pursuit of research career nor was it translated into the reason for leaving the dual clinical-research career pathway. Results revealed specific limitations presented by the research environment in newly emerging Asian AMCs. To retain a vibrant clinician-scientist workforce, additional measures are needed, aiming to improve institutional culture of research, build mentoring networks, adopt effective tools for tracking career progress and provide a clear and viable career progression path for clinician-scientist. Further research might explore the cross-cultural differences in managing work-life balance in academic medicine. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All

Perfusion of surgical cavity wall enhancement in early post-treatment MR imaging may stratify the time-to-progression in glioblastoma.

Directory of Open Access Journals (Sweden)

Ji Eun Park

Full Text Available To determine if perfusion in surgical cavity wall enhancement (SCWE obtained in early post-treatment MR imaging can stratify time-to-progression (TTP in glioblastoma.This study enrolled 60 glioblastoma patients with more than 5-mm-thick SCWEs as detected on contrast-enhanced MR imaging after concurrent chemoradiation therapy. Two independent readers categorized the shape and perfusion state of SCWEs as nodular or non-nodular and as having positive or negative perfusion compared with the contralateral grey matter on arterial spin labeling (ASL. The perfusion fraction on ASL within the contrast-enhancing lesion was calculated. The independent predictability of TTP was analyzed using the Kaplan-Meier method and Cox proportional hazards modelling.The perfusion fraction was higher in the non-progression group, significantly for reader 2 (P = 0.03 and borderline significantly for reader 1 (P = 0.08. A positive perfusion state and (P = 0.02 a higher perfusion fraction of the SCWE were found to become an independent predictor of longer TTP (P = 0.001 for reader 1 and P < 0.001 for reader 2. The contrast enhancement pattern did not become a TTP predictor.Assessment of perfusion in early post-treatment MR imaging can stratify TTP in patients with glioblastoma for adjuvant temozolomide therapy. Positive perfusion in SCWEs can become a predictor of a longer TTP.

Polyploidy and Mitotic Cell Death Are Two Distinct HIV-1 Vpr-Driven Outcomes in Renal Tubule Epithelial Cells.

Science.gov (United States)

Payne, Emily H; Ramalingam, Dhivya; Fox, Donald T; Klotman, Mary E

2018-01-15

Prior studies have found that HIV, through the Vpr protein, promotes genome reduplication (polyploidy) in infection-surviving epithelial cells within renal tissue. However, the temporal progression and molecular regulation through which Vpr promotes polyploidy have remained unclear. Here we define a sequential progression to Vpr-mediated polyploidy in human renal tubule epithelial cells (RTECs). We found that as in many cell types, Vpr first initiates G 2 cell cycle arrest in RTECs. We then identified a previously unreported cascade of Vpr-dependent events that lead to renal cell survival and polyploidy. Specifically, we found that a fraction of G 2 -arrested RTECs reenter the cell cycle. Following this cell cycle reentry, two distinct outcomes occur. Cells that enter complete mitosis undergo mitotic cell death due to extra centrosomes and aberrant division. Conversely, cells that abort mitosis undergo endoreplication to become polyploid. We further show that multiple small-molecule inhibitors of the phosphatidylinositol 3-kinase-related kinase (PIKK) family, including those that target ATR, ATM, and mTOR, indirectly prevent Vpr-mediated polyploidy by preventing G 2 arrest. In contrast, an inhibitor that targets DNA-dependent protein kinase (DNA-PK) specifically blocks the Vpr-mediated transition from G 2 arrest to polyploidy. These findings outline a temporal, molecularly regulated path to polyploidy in HIV-positive renal cells. IMPORTANCE Current cure-focused efforts in HIV research aim to elucidate the mechanisms of long-term persistence of HIV in compartments. The kidney is recognized as one such compartment, since viral DNA and mRNA persist in the renal tissues of HIV-positive patients. Further, renal disease is a long-term comorbidity in the setting of HIV. Thus, understanding the regulation and impact of HIV infection on renal cell biology will provide important insights into this unique HIV compartment. Our work identifies mechanisms that distinguish

Developing and validating a predictive model for stroke progression

OpenAIRE

Craig, L.E.; Wu, Olivia; Gilmour, H.; Barber, M.; Langhorne, P.

2011-01-01

Background: Progression is believed to be a common and important complication in acute stroke, and has been associated with increased mortality and morbidity. Reliable identification of predictors of early neurological deterioration could potentially benefit routine clinical care. The aim of this study was to identify predictors of early stroke progression using two independent patient cohorts. \\ud \\ud Methods: Two patient cohorts were used for this study – the first cohort formed the trainin...

Dysregulation of mitotic machinery genes precedes genome instability during spontaneous pre-malignant transformation of mouse ovarian surface epithelial cells

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Ulises Urzúa

2016-10-01

Full Text Available Abstract Background Based in epidemiological evidence, repetitive ovulation has been proposed to play a role in the origin of ovarian cancer by inducing an aberrant wound rupture-repair process of the ovarian surface epithelium (OSE. Accordingly, long term cultures of isolated OSE cells undergo in vitro spontaneous transformation thus developing tumorigenic capacity upon extensive subcultivation. In this work, C57BL/6 mouse OSE (MOSE cells were cultured up to passage 28 and their RNA and DNA copy number profiles obtained at passages 2, 5, 7, 10, 14, 18, 23, 25 and 28 by means of DNA microarrays. Gene ontology, pathway and network analyses were focused in passages earlier than 20, which is a hallmark of malignancy in this model. Results At passage 14, 101 genes were up-regulated in absence of significant DNA copy number changes. Among these, the top-3 enriched functions (>30 fold, adj p < 0.05 comprised 7 genes coding for centralspindlin, chromosome passenger and minichromosome maintenance protein complexes. The genes Ccnb1 (Cyclin B1, Birc5 (Survivin, Nusap1 and Kif23 were the most recurrent in over a dozen GO terms related to the mitotic process. On the other hand, Pten plus the large non-coding RNAs Malat1 and Neat1 were among the 80 down-regulated genes with mRNA processing, nuclear bodies, ER-stress response and tumor suppression as relevant terms. Interestingly, the earliest discrete segmental aneuploidies arose by passage 18 in chromosomes 7, 10, 11, 13, 15, 17 and 19. By passage 23, when MOSE cells express the malignant phenotype, the dysregulated gene expression repertoire expanded, DNA imbalances enlarged in size and covered additional loci. Conclusion Prior to early aneuploidies, overexpression of genes coding for the mitotic apparatus in passage-14 pre-malignant MOSE cells indicate an increased proliferation rate suggestive of replicative stress. Concomitant down-regulation of nuclear bodies and RNA processing related genes

Accumulation of senescent cells in mitotic tissue of aging primates.

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Jeyapalan, Jessie C; Ferreira, Mark; Sedivy, John M; Herbig, Utz

2007-01-01

Cellular senescence, a stress induced growth arrest of somatic cells, was first documented in cell cultures over 40 years ago, however its physiological significance has only recently been demonstrated. Using novel biomarkers of cellular senescence we examined whether senescent cells accumulate in tissues from baboons of ages encompassing the entire lifespan of this species. We show that dermal fibroblasts, displaying markers of senescence such as telomere damage, active checkpoint kinase ATM, high levels of heterochromatin proteins and elevated levels of p16, accumulate in skin biopsies from baboons with advancing age. The number of dermal fibroblasts containing damaged telomeres reaches a value of over 15% of total fibroblasts, whereas 80% of cells contain high levels of the heterochromatin protein HIRA. In skeletal muscle, a postmitotic tissue, only a small percentage of myonuclei containing damaged telomeres were detected regardless of animal age. The presence of senescent cells in mitotic tissues might therefore be a contributing factor to aging and age related pathology and provides further evidence that cellular senescence is a physiological event.

ADAPTATION AND PROGRESS THROUGH CHANGE MANAGEMENT

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Gabriela MEHEDINTU

2016-12-01

Full Text Available The technological progress, digitization and the explosion of information significantly change how individuals, the business environment, and society act, develop and add value. New, interdisciplinary approaches, constantly adapted and sustainable both at the micro and the macro levels are required. Within a company, change management is a systematic element of the strategic business process and involves the early identification of the opportunity of the employees’ development, courage, commitment and flexibility; under no circumstances should it be seen as a risk and instability factor, as it may be considered in the early stages. The example presented in this article proves that the openness to change and continuous improvement develops advantages, optimizes processes and sustains long-term progress.

Study on severe fuel damage and in-vessel melt progression

International Nuclear Information System (INIS)

Kim, Hee Dong; Kim, Sang Baik; Lee, Gyu Jung

1992-06-01

In-vessel core melt progression describes the progression of the state of a reactor core from core uncovery up to reactor vessel melt through in uncovered accidents or through temperature stabilization in accidents recovered by core reflooding. Melt progression can be thought as two parts; early melt progression and late melt progression. Early phase of core melt progression includes the progression of core material melting and relocation, which mostly consist of metallic materials. On the other hand, the late phase of core melt progression involves ceramic material melt and relocation to the lower plenum and heat-up the reactor vessel lower head. A large number of information are available for the early melt progression through experiments such as SFD, DF, FLHT test and utilized in the severe accident analysis codes. However, understanding of the late phase melt progression phenomenology is based primary on TMI-2 core examinations and not much experimental information is available. Especilally, the great uncertainties exist in vessel failure mode, melt composition, mass, and temperature. Further research is planned to perform to reduce the uncertainties in understanding of core melt down accidents as parts of long term melt progression research program. A study on the core melt progression at KAERI has been being performed through the Severe Accident Research Program with USNRC. KAERI staff had participated in the PBF SFD experiments at INEL and analyses of experiments were performed using SCDAP code. Experiments of core melt program have not been carried out at KAERI yet. It is planned that further research on core melt down accidents will be performed, which is related to design of future generations of nuclear reactors as parts of long-term project for improvement of nuclear reactor safety. (Author)

Effect of disease stage on progression of hydroxychloroquine retinopathy.

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Marmor, Michael F; Hu, Julia

2014-09-01

Hydroxychloroquine sulfate retinopathy can progress after the drug is stopped. It is not clear how this relates to the stage of retinopathy or whether early screening with modern imaging technology can prevent progression and visual loss. To determine the relationship between progression of retinopathy and the severity of disease using objective data from optical coherence tomography and assess the value of early screening for the toxic effects of hydroxychloroquine. Clinical findings in patients with hydroxychloroquine retinopathy were monitored with repeated anatomical and functional examinations for 13 to 40 months after the drug was stopped in a referral practice in a university medical center. Eleven patients participated, with the severity of toxic effects categorized as early (patchy parafoveal damage shown on field or objective testing), moderate (a 50%-100% parafoveal ring of optical coherence tomography thinning but intact retinal pigment epithelium), and severe (visible bull's-eye damage). Visual acuity, white 10-2 visual field pattern density plots, fundus autofluorescence, spectral-density optical coherence tomography cross sections, thickness (from cube diagrams), and ellipsoid zone length. Visual acuity and visual fields showed no consistent change. Fundus autofluorescence showed little or no change except in severe cases in which the bull's-eye damage expanded progressively. Optical coherence tomography cross sections showed little visible change in early and moderate cases but progressive foveal thinning (approximately 7 μm/y) and loss of ellipsoid zone (in the range of 100 μm/y) in severe cases, which was confirmed by quantitative measurements. The measurements also showed some foveal thinning (approximately 4 μm/y) and deepening of parafoveal loss in moderate cases, but the breadth of the ellipsoid zone remained constant in both early and moderate cases. A few cases showed a suggestion of ellipsoid zone improvement. Patients with

Effect of uvs1, uvs2 and xrs mutations on the radiosensitivity and the induced mitotic recombination frequency in diploid yeast cells

International Nuclear Information System (INIS)

Suslova, N.G.; Fedorova, I.V.; Zheleznyakova, N.Yu.

1975-01-01

The influence of the loci of radiosensitivity uvs1, uvs2, and xrs in the homozygous state at the diploid level on the sensitivity to UV and ionizing radiation and induced mitotic recombination was studied in the yeast Sacch. cerevisiae. Hypersensitivity to UV irradiation was detected in the diploids uvs2 uvs2 xrs xrs in comparision with the corresponding control. The diploid uvs1 uvs1 uvs2 uvs2 does not differ in UV sensitivity from the diploid uvs1 uvs1 UVS2 UVS2. These facts demonstrate that the uvs1 and uvs2 mutations, on the one hand, and the xrs mutations, on the other, normally control different pathways of elimination of UV-induced damages. It was shown that the diploid uvs2 uvs2 xrs3 xrs3 is far more sensitive to the lethal action of x rays than the control diploid UVS2 UVS2 xrs3 xrs3. Consequently, the mutations uvs2 and xrs3 block different modes of repair of damages induced by ionizing radiation. In all the double-mutant diploids, the frequency of mitotic recombination induced by UV rays increases sharply in comparison with that of the radioresistant diploids UVS UVS XRS XRS and the UV-sensitive diploids uvs2 uvs2 XRS XRS. Possible causes of the observed phenomenon are discussed. It was established that in a diploid homozygous for the loci uvs2 xrs5, the frequency of mitotic recombination induced by x rays increases extremely sharply. This fact confirms the hypothesis that the gene product of the locus uvs2 participates in the repair of DNA after the action of ionizing radiation. (author)

The SFP1 gene product of Saccharomyces cerevisiae regulates G2/M transitions during the mitotic cell cycle and DNA-damage response

International Nuclear Information System (INIS)

Xu, Z.; Norris, D.

1998-01-01

In eukaryotic cells, checkpoint pathways arrest cell-cycle progression if a particular event has failed to complete appropriately or if an important intracellular structure is defective or damaged. Saccharomyces cerevisiae strains that lack the SFP1 gene fail to arrest at the G2 DNA-damage checkpoint in response to genomic injury, but maintain their ability to arrest at the replication and spindle-assembly checkpoints. sfp1D mutants are characterized by a premature entrance into mitosis during a normal (undamaged) cell cycle, while strains that overexpress Sfp1p exhibit delays in G2. Sfp1p therefore acts as a repressor of the G2/M transition, both in the normal cell cycle and in the G2 checkpoint pathway. Sfp1 is a nuclear protein with two Cys2His2 zinc-finger domains commonly found in transcription factors. We propose that Sfp1p regulates the expression of gene products involved in the G2/M transition during the mitotic cell cycle and the DNA-damage response. In support of this model, overexpression of Sfp1p induces the expression of the PDS1 gene, which is known to encode a protein that regulates the G2 checkpoint. (author)

3'-Deoxy-3'-{sup 18}F-fluorothymidine positron emission tomography as an early predictor of disease progression in patients with advanced and metastatic pancreatic cancer

Energy Technology Data Exchange (ETDEWEB)

Challapalli, Amarnath; Barwick, Tara; Merchant, Shairoz [Imperial College London (ICL), Department of Surgery and Cancer, London (United Kingdom); Pearson, Rachel A.; Howell, Elizabeth C.; Maxwell, Ross J. [Newcastle University, Northern Institute for Cancer Research, Newcastle (United Kingdom); Mauri, Francesco [Imperial College Healthcare NHS Trust, Department of Pathology, London (United Kingdom); Sumpter, Katherine [Northern Centre for Cancer Care, Newcastle Upon Tyne Hospitals NHS Foundation Trust, London (United Kingdom); Aboagye, Eric O. [Imperial College London (ICL), Department of Surgery and Cancer, London (United Kingdom); ICL, Hammersmith Hospital, Department of Surgery and Cancer, London (United Kingdom); Sharma, Rohini [ICL, Department of Investigative Medicine, London (United Kingdom)

2015-05-01

3'-Deoxy-3'-{sup 18}F-fluorothymidine (FLT) positron emission tomography (PET) has limited utility in abdominal imaging due to high physiological hepatic uptake of tracer. We evaluated FLT PET/CT combined with a temporal-intensity information-based voxel-clustering approach termed kinetic spatial filtering (FLT PET/CT{sub KSF}) for early prediction of response and survival outcomes in locally advanced and metastatic pancreatic cancer patients receiving gemcitabine-based chemotherapy. Dynamic FLT PET/CT data were collected before and 3 weeks after the first cycle of chemotherapy. Changes in tumour FLT PET/CT variables were determined. The primary end point was RECIST 1.1 response on contrast-enhanced CT after 3 months of therapy. Twenty patients were included. Visual distinction between tumours and normal pancreas was seen in FLT PET{sub KSF} images. All target lesions (>2 cm), including all primary pancreatic tumours, were visualised. Of the 11 liver metastases, 3 (<2 cm) were not visible after kinetic filtering. Of the 20 patients, 7 progressed (35 %). Maximum standardised uptake value at 60 min post-injection (SUV{sub 60,max}) significantly increased in patients with disease progression (p = 0.04). Receiver-operating characteristic curve analysis indicated that a threshold of SUV{sub 60,max} increase of ≥ 12 % resulted in sensitivity, specificity and positive predictive value (PPV) of 71, 100 and 100 %, respectively [area under the curve (AUC) 0.90, p = 0.0001], to predict patients with disease progression. Changes in SUV{sub 60,max} were not predictive of survival. FLT PET/CT detected changes in proliferation, with early increase in SUV{sub 60,max} predicting progressive disease with a high specificity and PPV. Therefore, FLT PET/CT could be used as an early response biomarker for gemcitabine-based chemotherapy, to select a poor prognostic group who may benefit from novel therapeutic agents in advanced and metastatic pancreatic cancer. (orig.)

Lipid raft disarrangement as a result of neuropathological progresses: a novel strategy for early diagnosis?

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Marin, R; Rojo, J A; Fabelo, N; Fernandez, C E; Diaz, M

2013-08-15

Lipid rafts are the preferential site of numerous membrane signaling proteins which are involved in neuronal functioning and survival. These proteins are organized in multiprotein complexes, or signalosomes, in close contact with lipid classes particularly represented in lipid rafts (i.e. cholesterol, sphingolipids and saturated fatty acids), which may contribute to physiological responses leading to neuroprotection. Increasing evidence indicates that alteration of lipid composition in raft structures as a consequence of neuropathologies, such as Alzheimer's disease (AD) and Parkinson's disease (PD), causes a dramatic increase in lipid raft order. These phenomena may correlate with perturbation of signalosome activities, likely contributing to neurodegenerative progression. Interestingly, significant disruption of stable raft microenvironments has been already observed in the first stages of either AD or PD, suggesting that these alterations may represent early events in the neuropathological development. In this regard, the search for biochemical markers, such as specific metabolic products altered in the brain at the first steps of the disease, presently represents an important challenge for early diagnostic strategies. Alterations of these biomarkers may be reflected in either plasma or cerebrospinal fluid, thus representing a potential strategy to predict an accurate diagnosis. We propose that pathologically-linked lipid raft markers may be interesting candidates to be explored at this level, although it has not been studied so far to what extent alteration of different signalosome components may be reflected in peripheral fluids. In this mini-review, we will discuss on relevant aspects of lipid rafts that contribute to the modulation of neuropathological events related to AD and PD. An interesting hypothesis is that anomalies on raft biomarkers measured at peripheral fluids might mirror the lipid raft pathology observed in early stages of AD and PD. Copyright

Planning ideology and geographic thought in the early twentieth century: Charles Whitnall's progressive era park designs for socialist Milwaukee.

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Platt, Lorne A

2010-01-01

As Milwaukee’s chief park planner in the early to mid-twentieth century, Charles Whitnall responded to the various underlying ideologies of the period within which he worked. His preference for parks was a political and physical response to and remedy for the industrialized and heavily congested city he called home. By examining the Progressive Era discourse associated with planning, this article situates Whitnall’s work within the political, aesthetic, and environmental contexts of geographic thought that influenced his plans for Milwaukee. In promoting a physical awareness associated with the natural features of the region and responding to the sociopolitical framework of contemporaries such as Ebenezer Howard, Whitnall incorporated a sense of compassion within his planning. He responded to the preexisting beer gardens of Pabst and Schlitz, as well as Olmsted-designed park spaces, by advocating for decentralization as part of a broader socialist agenda that had swept through Milwaukee during the early 1900s.

KSHV cell attachment sites revealed by ultra sensitive tyramide signal amplification (TSA) localize to membrane microdomains that are up-regulated on mitotic cells.

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Garrigues, H Jacques; Rubinchikova, Yelena E; Rose, Timothy M

2014-03-01

Cell surface structures initiating attachment of Kaposi's sarcoma-associated herpesvirus (KSHV) were characterized using purified hapten-labeled virions visualized by confocal microscopy with a sensitive fluorescent enhancement using tyramide signal amplification (TSA). KSHV attachment sites were present in specific cellular domains, including actin-based filopodia, lamellipodia, ruffled membranes, microvilli and intercellular junctions. Isolated microdomains were identified on the dorsal surface, which were heterogeneous in size with a variable distribution that depended on cellular confluence and cell cycle stage. KSHV binding domains ranged from scarce on interphase cells to dense and continuous on mitotic cells, and quantitation of bound virus revealed a significant increase on mitotic compared to interphase cells. KSHV also bound to a supranuclear domain that was distinct from microdomains in confluent and interphase cells. These results suggest that rearrangement of the cellular membrane during mitosis induces changes in cell surface receptors implicated in the initial attachment stage of KSHV entry. Copyright © 2014 Elsevier Inc. All rights reserved.

Perturbation of Incenp function impedes anaphase chromatid movements and chromosomal passenger protein flux at centromeres.

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Ahonen, Leena J; Kukkonen, Anu M; Pouwels, Jeroen; Bolton, Margaret A; Jingle, Christopher D; Stukenberg, P Todd; Kallio, Marko J

2009-02-01

Incenp is an essential mitotic protein that, together with Aurora B, Survivin, and Borealin, forms the core of the chromosomal passenger protein complex (CPC). The CPC regulates various mitotic processes and functions to maintain genomic stability. The proper subcellular localization of the CPC and its full catalytic activity require the presence of each core subunit in the complex. We have investigated the mitotic tasks of the CPC using a function blocking antibody against Incenp microinjected into cells at different mitotic phases. This method allowed temporal analysis of CPC functions without perturbation of complex assembly or activity prior to injection. We have also studied the dynamic properties of Incenp and Aurora B using fusion protein photobleaching. We found that in early mitotic cells, Incenp and Aurora B exhibit dynamic turnover at centromeres, which is prevented by the anti-Incenp antibody. In these cells, the loss of centromeric CPC turnover is accompanied by forced mitotic exit without the execution of cytokinesis. Introduction of anti-Incenp antibody into early anaphase cells causes abnormalities in sister chromatid separation through defects in anaphase spindle functions. In summary, our data uncovers new mitotic roles for the CPC in anaphase and proposes that CPC turnover at centromeres modulates spindle assembly checkpoint signaling.

X-ray induction of mitotic and meiotic chromosome aberrations

International Nuclear Information System (INIS)

Yao, K.T.S.

1980-01-01

In 1964 six pairs of rat kangaroo (Potorous tridactylis) were obtained from Australia. The tissues of these animals were used to initiate cell lines. Since this species has a low chromosome number of six pairs, each pair with its own distinctive morphology, it is particularly favorable for cytogenetic research. In cell cultures derived from the corneal endothelial tissues of one animal there emerged a number of haploid cells. The number of haploid cells in the cultures reached as high as 20% of the total mitotic configurations. The in vitro diploid and haploid mixture cell cultures could be a resemblance or a coincidence to the mixture existence of the diploid primary spermatocytes and the haploid secondary spermatocytes (gametes) in the in vivo testicular tissues of the male animals. It would be interesting to compare reactions of the haploid and diploid cell mixture, either in the cultures or in the testes, to x-ray exposure. Two other studies involving x-ray effects on Chinese hamster oocyte maturation and meiotic chromosomes and the x-ray induction of Chinese hamster spermatocyte meiotic chromosome aberrations have been done in this laboratory. A review of these three studies involving diploid and haploid chromosomes may lead to further research in the x-ray induction of chromosome aberrations

Detection of ATM germline variants by the p53 mitotic centrosomal localization test in BRCA1/2-negative patients with early-onset breast cancer.

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Prodosmo, Andrea; Buffone, Amelia; Mattioni, Manlio; Barnabei, Agnese; Persichetti, Agnese; De Leo, Aurora; Appetecchia, Marialuisa; Nicolussi, Arianna; Coppa, Anna; Sciacchitano, Salvatore; Giordano, Carolina; Pinnarò, Paola; Sanguineti, Giuseppe; Strigari, Lidia; Alessandrini, Gabriele; Facciolo, Francesco; Cosimelli, Maurizio; Grazi, Gian Luca; Corrado, Giacomo; Vizza, Enrico; Giannini, Giuseppe; Soddu, Silvia

2016-09-06

Variant ATM heterozygotes have an increased risk of developing cancer, cardiovascular diseases, and diabetes. Costs and time of sequencing and ATM variant complexity make large-scale, general population screenings not cost-effective yet. Recently, we developed a straightforward, rapid, and inexpensive test based on p53 mitotic centrosomal localization (p53-MCL) in peripheral blood mononuclear cells (PBMCs) that diagnoses mutant ATM zygosity and recognizes tumor-associated ATM polymorphisms. Fresh PBMCs from 496 cancer patients were analyzed by p53-MCL: 90 cases with familial BRCA1/2-positive and -negative breast and/or ovarian cancer, 337 with sporadic cancers (ovarian, lung, colon, and post-menopausal breast cancers), and 69 with breast/thyroid cancer. Variants were confirmed by ATM sequencing. A total of seven individuals with ATM variants were identified, 5/65 (7.7 %) in breast cancer cases of familial breast and/or ovarian cancer and 2/69 (2.9 %) in breast/thyroid cancer. No variant ATM carriers were found among the other cancer cases. Excluding a single case in which both BRCA1 and ATM were mutated, no p53-MCL alterations were observed in BRCA1/2-positive cases. These data validate p53-MCL as reliable and specific test for germline ATM variants, confirm ATM as breast cancer susceptibility gene, and highlight a possible association with breast/thyroid cancers.

A SEL1L mutation links a canine progressive early-onset cerebellar ataxia to the endoplasmic reticulum-associated protein degradation (ERAD machinery.

Directory of Open Access Journals (Sweden)

Kaisa Kyöstilä

Full Text Available Inherited ataxias are characterized by degeneration of the cerebellar structures, which results in progressive motor incoordination. Hereditary ataxias occur in many species, including humans and dogs. Several mutations have been found in humans, but the genetic background has remained elusive in dogs. The Finnish Hound suffers from an early-onset progressive cerebellar ataxia. We have performed clinical, pathological, and genetic studies to describe the disease phenotype and to identify its genetic cause. Neurological examinations on ten affected dogs revealed rapidly progressing generalized cerebellar ataxia, tremors, and failure to thrive. Clinical signs were present by the age of 3 months, and cerebellar shrinkage was detectable through MRI. Pathological and histological examinations indicated cerebellum-restricted neurodegeneration. Marked loss of Purkinje cells was detected in the cerebellar cortex with secondary changes in other cortical layers. A genome-wide association study in a cohort of 31 dogs mapped the ataxia gene to a 1.5 Mb locus on canine chromosome 8 (p(raw = 1.1x10(-7, p(genome = 7.5x10(-4. Sequencing of a functional candidate gene, sel-1 suppressor of lin-12-like (SEL1L, revealed a homozygous missense mutation, c.1972T>C; p.Ser658Pro, in a highly conserved protein domain. The mutation segregated fully in the recessive pedigree, and a 10% carrier frequency was indicated in a population cohort. SEL1L is a component of the endoplasmic reticulum (ER-associated protein degradation (ERAD machinery and has not been previously associated to inherited ataxias. Dysfunctional protein degradation is known to cause ER stress, and we found a significant increase in expression of nine ER stress responsive genes in the cerebellar cortex of affected dogs, supporting the pathogenicity of the mutation. Our study describes the first early-onset neurodegenerative ataxia mutation in dogs, establishes an ERAD-mediated neurodegenerative

Novel Mad2-targeting miR-493-3p controls mitotic fidelity and cancer cells' sensitivity to paclitaxel.

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Tambe, Mahesh; Pruikkonen, Sofia; Mäki-Jouppila, Jenni; Chen, Ping; Elgaaen, Bente Vilming; Straume, Anne Hege; Huhtinen, Kaisa; Cárpen, Olli; Lønning, Per Eystein; Davidson, Ben; Hautaniemi, Sampsa; Kallio, Marko J

2016-03-15

The molecular pathways that contribute to the proliferation and drug response of cancer cells are highly complex and currently insufficiently characterized. We have identified a previously unknown microRNA-based mechanism that provides cancer cells means to stimulate tumorigenesis via increased genomic instability and, at the same time, evade the action of clinically utilized microtubule drugs. We demonstrate miR-493-3p to be a novel negative regulator of mitotic arrest deficient-2 (MAD2), an essential component of the spindle assembly checkpoint that monitors the fidelity of chromosome segregation. The microRNA targets the 3' UTR of Mad2 mRNA thereby preventing translation of the Mad2 protein. In cancer cells, overexpression of miR-493-3p induced a premature mitotic exit that led to increased frequency of aneuploidy and cellular senescence in the progeny cells. Importantly, excess of the miR-493-3p conferred resistance of cancer cells to microtubule drugs. In human neoplasms, miR-493-3p and Mad2 expression alterations correlated with advanced ovarian cancer forms and high miR-493-3p levels were associated with reduced survival of ovarian and breast cancer patients with aggressive tumors, especially in the paclitaxel therapy arm. Our results suggest that intratumoral profiling of miR-493-3p and Mad2 levels can have diagnostic value in predicting the efficacy of taxane chemotherapy.

Preemptive mechanical ventilation can block progressive acute lung injury.

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Sadowitz, Benjamin; Jain, Sumeet; Kollisch-Singule, Michaela; Satalin, Joshua; Andrews, Penny; Habashi, Nader; Gatto, Louis A; Nieman, Gary

2016-02-04

Mortality from acute respiratory distress syndrome (ARDS) remains unacceptable, approaching 45% in certain high-risk patient populations. Treating fulminant ARDS is currently relegated to supportive care measures only. Thus, the best treatment for ARDS may lie with preventing this syndrome from ever occurring. Clinical studies were examined to determine why ARDS has remained resistant to treatment over the past several decades. In addition, both basic science and clinical studies were examined to determine the impact that early, protective mechanical ventilation may have on preventing the development of ARDS in at-risk patients. Fulminant ARDS is highly resistant to both pharmacologic treatment and methods of mechanical ventilation. However, ARDS is a progressive disease with an early treatment window that can be exploited. In particular, protective mechanical ventilation initiated before the onset of lung injury can prevent the progression to ARDS. Airway pressure release ventilation (APRV) is a novel mechanical ventilation strategy for delivering a protective breath that has been shown to block progressive acute lung injury (ALI) and prevent ALI from progressing to ARDS. ARDS mortality currently remains as high as 45% in some studies. As ARDS is a progressive disease, the key to treatment lies with preventing the disease from ever occurring while it remains subclinical. Early protective mechanical ventilation with APRV appears to offer substantial benefit in this regard and may be the prophylactic treatment of choice for preventing ARDS.