Calcium and Mitosis

Science.gov (United States)

Hepler, P.

1983-01-01

Although the mechanism of calcium regulation is not understood, there is evidence that calcium plays a role in mitosis. Experiments conducted show that: (1) the spindle apparatus contains a highly developed membrane system that has many characteristics of sarcoplasmic reticulum of muscle; (2) this membrane system contains calcium; and (3) there are ionic fluxes occurring during mitosis which can be seen by a variety of fluorescence probes. Whether the process of mitosis can be modulated by experimentally modulating calcium is discussed.

Syntheses of Quinazoline-2,4-dione Alkaloids and Analogues from Mexican Zanthoxylum Species â€

Directory of Open Access Journals (Sweden)

R. Somanathan

2004-06-01

Full Text Available Quinazolinone and quinazolinedione derivatives are of considerable interest due to their wide array of pharmacological properties. In this paper we report the synthesis of ten quinazolinediones. The previous isolation of two of these compounds, namely 1-methyl-3-(2'-phenylethyl-1H,3H-quinazoline-2,4-dione and 1-methyl-3-[2'-(4'- methoxyphenylethyl]-lH,3H-quinazoline-2,4-dione, from the seed husks of Mexican Zanthoxylum species has been reported

Solvent/oxidant-switchable synthesis of multisubstituted quinazolines and benzimidazoles via metal-free selective oxidative annulation of arylamidines.

Science.gov (United States)

Lin, Jian-Ping; Zhang, Feng-Hua; Long, Ya-Qiu

2014-06-06

A fast and simple divergent synthesis of multisubstituted quinazolines and benzimidazoles was developed from readily available amidines, via iodine(III)-promoted oxidative C(sp(3))-C(sp(2)) and C(sp(2))-N bond formation in nonpolar and polar solvents, respectively. Further selective synthesis of quinazolines in polar solvent was realized by TEMPO-catalyzed sp(3)C-H/sp(2)C-H direct coupling of the amidine with K2S2O8 as the oxidant. No metal, base, or other additives were needed.

Synthesis of Novel 3H-Quinazolin-4-ones Containing Pyrazolinone, Pyrazole and Pyrimidinone Moieties

Directory of Open Access Journals (Sweden)

Abdel-Basset M. Shokr

2003-04-01

Full Text Available The diazonium salt of 3-(4-aminophenyl-2-methyl-3H-quinazolin-4-one (2a and its 6-bromo derivative 2b reacted with some active methylene compounds, namely ethyl acetoacetate (3, ethyl cyanoacetate (4 and acetylacetone (5, to afford the corresponding hydrazono quinazolinone derivatives 6-8. Treatment of 6a,b with hydrazine hydrate or phenyl hydrazine in refluxing ethanol afforded the corresponding pyrazolin-5-one derivatives of 3H-quinazolin-4-one 9a-d. Cyclization of 7a,b with hydrazine hydrate yielded the corresponding products 10a,b. Reaction of 8a,b with phenyl hydrazine or with urea afforded the corresponding derivatives 11a,b and 12a,b, respectively. Compounds 6-12 were identified by C,H,N analysis, IR, 1H-NMR, 13C-NMR and mass spectroscopy.

Novel functions of plant cyclin-dependent kinase inhibitors, ICK1/KRP1, can act non-cell-autonomously and inhibit entry into mitosis

DEFF Research Database (Denmark)

Weinl, Christina; Marquardt, Sebastian; Kuijt, Suzanne J H

2005-01-01

numbers of cells consistent with a function of CKIs in blocking the G1-S cell cycle transition. Here, we demonstrate that at least one inhibitor from Arabidopsis, ICK1/KRP1, can also block entry into mitosis but allows S-phase progression causing endoreplication. Our data suggest that plant CKIs act...... independently from ICK1/KRP1-induced endoreplication. Strikingly, we found that endoreplicated cells were able to reenter mitosis, emphasizing the high degree of flexibility of plant cells during development. Moreover, we show that in contrast with animal CDK inhibitors, ICK1/KRP1 can move between cells...

2-([1,2,4]triazolo[1,5-c]quinazolin-2-yl-alkyl-(alkaryl-, aryl--amines and their derivatives. (3Н-quinazolin-4-ylidenhydrazides (1,3-dioxo-1,3-dihydro-2H-isoindol-2-ylalkyl-(alkaryl-, aryl-carboxylic acids: features of synthesis, modification and ant

Directory of Open Access Journals (Sweden)

Yu. V. Martynenko

2016-08-01

Full Text Available The combination of different «pharmacophore» components in one structure connected via «linker» functional groups is one of the major and justified approaches for the synthesis of new biologically active substances. In this area (3Н-quinazoline-4-ylidenhydrazides (1,3-dioxo-1,3-dihydro-2H-іsoindol-2-yl-alkyl-(aralkyl-, aryl-carboxylic acids are the most interesting compounds. They contain quinazoline and іsoindole fragments united through аlkyl, аlkaryl and аryl groups and furthermore can be used for the synthesis of new heterocycles. Aim: The purpose of this work is to find antimicrobial and antifungal agents among (3H-quinazolin-4-ylidenehydrazides (1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl-alkyl-(alkaryl-, aryl-carboxylic acids and their fused derivatives and to establish physical-chemical properties of these compounds and to correlate «structure – activity relationship» for structure optimization. Methods and results. The study of microbiological activity was conducted by disco-diffusion method on Mueller-Hinton agar on the following strains of microorganisms: gram-positive cocci (Staphylococcus aureus ATCC 25923, Enterococcus aeruginosa, E. faecalis ATCC 29212, gram-negative bacteria (Pseudomonas aeruginosa PSS27853, Escherichia coli ATCC 25922, facultative anaerobic gram-negative bacteria (Klebsiella pneumoniaе and fungi (Candida albicans ATCC 885653. Conclusion. The protected aminoacids were used to synthesize unknown (3H-quinazolin-4-ylidenehydrazides (1,3-dioxo-1,3-dihydroisoindolo-2-yl-alkyl-(alkaryl-, aryl-carboxylic acids in the reactions of nucleophilic substitution for the first time. While new [1,2,4]triazolo[1,5-c]quinazolin-2-yl-alkyl-(alkaryl-, aryl-- isoindol-1,3(2H-diones were received by heterocyclization of the last. Structure and identity have been confirmed by elemental analysis, physical and chemical methods (1H NMR spectroscopy, mass-spectrometry. Analysis of the results of microbiological study shows, that

MIIP, a cytoskeleton regulator that blocks cell migration and invasion, delays mitosis, and suppresses tumorogenesis.

Science.gov (United States)

Wang, Yingmei; Wen, Jing; Zhang, Wei

2011-02-01

The migration and invasion inhibitory protein (MIIP) was initially discovered in a yeast two-hybrid screen for proteins that interact and inhibit the migration and invasion-promoting protein insulin-like growth factor binding protein 2 (IGFBP2). Recent studies have shown that MIIP not only modulates IGFBP2 but also regulates microtubule by binding to and inhibiting HDAC6, a class 2 histone deacetylase that deacetylates α-tubulin, heat-shock protein 90 (HSP90), and cortactin. In addition, MIIP also regulates the mitosis checkpoint, another microtubule-associated process. The location of the MIIP gene in chromosomal region 1p36, a commonly deleted region in a broad spectrum of human cancers, and the observation that MIIP attenuates tumorigenesis in a mouse model suggest that it functions as a tumor-suppressor gene. This review summarizes the recent progress in characterizing this novel protein, which regulates cell migration and mitosis, two processes that rely on the highly coordinated dynamics of the microtubule and cytoskeleton systems.

Synthesis, biological evaluation and QSAR study of a series of substituted quinazolines as antimicrobial agents

Czech Academy of Sciences Publication Activity Database

Buha, V. M.; Rana, D. N.; Chhabria, M. T.; Chikhalia, K. H.; Mahajan, B. M.; Brahmkshatriya, Pathik; Shah, N. K.

2013-01-01

Roč. 22, č. 9 (2013), s. 4096-4109 ISSN 1054-2523 Institutional support: RVO:61388963 Keywords : antimicrobial agents * quantitative structure-activity relationship * genetic function approximation * quinazoline Subject RIV: CE - Biochemistry Impact factor: 1.612, year: 2012

2-([1,2,4]triazolo[1,5-c]quinazolin-2-yl-)alkyl-(alkaryl-, aryl-)-amines and their derivatives. (3Н-quinazolin-4-yliden)hydrazides (1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)alkyl-(alkaryl-, aryl-)carboxylic acids: features of synthesis, modification and ant

OpenAIRE

Yu. V. Martynenko; M. S. Kazunin; E. А. Selivanova; S. I. Kovalenko

2016-01-01

The combination of different «pharmacophore» components in one structure connected via «linker» functional groups is one of the major and justified approaches for the synthesis of new biologically active substances. In this area (3Н-quinazoline-4-yliden)hydrazides (1,3-dioxo-1,3-dihydro-2H-іsoindol-2-yl-)alkyl-(aralkyl-, aryl-)carboxylic acids are the most interesting compounds. They contain quinazoline and іsoindole fragments united through аlkyl, аlkaryl and аryl groups and furthermore can ...

Benzo[g]quinazolin-based scaffold derivatives as dual EGFR/HER2 inhibitors.

Science.gov (United States)

Ghorab, Mostafa M; Alsaid, Mansour S; Soliman, Aiten M; Al-Mishari, Abdullah A

2018-12-01

Targeting EGFR has proven to be beneficial in the treatment of several types of solid tumours. So, a series of novel 2-(4-oxo-3-(4-sulfamoylphenyl)-3,4-dihydrobenzo[g]quinazolin-2-ylthio)-N-substituted acetamide 5-19 were synthesised from the starting material 4-(2-mercapto-4-oxobenzo[g]quinazolin-3(4H)-yl) benzenesulfonamide 4, to be evaluated as dual EGFR/HER2 inhibitors. The target compounds 5-19, were screened for their cytotoxic activity against A549 lung cancer cell line. The percentage inhibition of EGFR enzyme was measured and compared with erlotinib as the reference drug. Compounds 6, 8, 10, and 16 showed excellent EGFR inhibitory activity and were further selected for screening as dual EGFR/HER2 inhibitors. The four selected compounds showed IC 50 ranging from 0.009 to 0.026 µM for EGFR and 0.021 to 0.069 µM for the HER2 enzyme. Compound 8 was found to be the most potent in this study with IC 50 0.009 and 0.021 µM for EGFR and HER2, respectively.

The terminal basal mitosis of chicken retinal Lim1 horizontal cells is not sensitive to cisplatin-induced cell cycle arrest.

Science.gov (United States)

Shirazi Fard, Shahrzad; Thyselius, Malin; All-Ericsson, Charlotta; Hallböök, Finn

2014-01-01

For proper development, cells need to coordinate proliferation and cell cycle-exit. This is mediated by a cascade of proteins making sure that each phase of the cell cycle is controlled before the initiation of the next. Retinal progenitor cells divide during the process of interkinetic nuclear migration, where they undergo S-phase on the basal side, followed by mitoses on the apical side of the neuroepithelium. The final cell cycle of chicken retinal horizontal cells (HCs) is an exception to this general cell cycle behavior. Lim1 expressing (+) horizontal progenitor cells (HPCs) have a heterogenic final cell cycle, with some cells undergoing a terminal mitosis on the basal side of the retina. The results in this study show that this terminal basal mitosis of Lim1+ HPCs is not dependent on Chk1/2 for its regulation compared to retinal cells undergoing interkinetic nuclear migration. Neither activating nor blocking Chk1 had an effect on the basal mitosis of Lim1+ HPCs. Furthermore, the Lim1+ HPCs were not sensitive to cisplatin-induced DNA damage and were able to continue into mitosis in the presence of γ-H2AX without activation of caspase-3. However, Nutlin3a-induced expression of p21 did reduce the mitoses, suggesting the presence of a functional p53/p21 response in HPCs. In contrast, the apical mitoses were blocked upon activation of either Chk1/2 or p21, indicating the importance of these proteins during the process of interkinetic nuclear migration. Inhibiting Cdk1 blocked M-phase transition both for apical and basal mitoses. This confirmed that the cyclin B1-Cdk1 complex was active and functional during the basal mitosis of Lim1+ HPCs. The regulation of the final cell cycle of Lim1+ HPCs is of particular interest since it has been shown that the HCs are able to sustain persistent DNA damage, remain in the cell cycle for an extended period of time and, consequently, survive for months.

SnapShot: Phosphoregulation of Mitosis.

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Burgess, Andrew; Vuong, Jenny; Rogers, Samuel; Malumbres, Marcos; O'Donoghue, Seán I

2017-06-15

During mitosis, a cell divides its duplicated genome into two identical daughter cells. This process must occur without errors to prevent proliferative diseases (e.g., cancer). A key mechanism controlling mitosis is the precise timing of more than 32,000 phosphorylation and dephosphorylation events by a network of kinases and counterbalancing phosphatases. The identity, magnitude, and temporal regulation of these events have emerged recently, largely from advances in mass spectrometry. Here, we show phosphoevents currently believed to be key regulators of mitosis. For an animated version of this SnapShot, please see http://www.cell.com/cell/enhanced/odonoghue2. Copyright © 2017. Published by Elsevier Inc.

TopBP1-mediated DNA processing during mitosis.

Science.gov (United States)

Gallina, Irene; Christiansen, Signe Korbo; Pedersen, Rune Troelsgaard; Lisby, Michael; Oestergaard, Vibe H

2016-01-01

Maintenance of genome integrity is crucial to avoid cancer and other genetic diseases. Thus faced with DNA damage, cells mount a DNA damage response to avoid genome instability. The DNA damage response is partially inhibited during mitosis presumably to avoid erroneous processing of the segregating chromosomes. Yet our recent study shows that TopBP1-mediated DNA processing during mitosis is highly important to reduce transmission of DNA damage to daughter cells. (1) Here we provide an overview of the DNA damage response and DNA repair during mitosis. One role of TopBP1 during mitosis is to stimulate unscheduled DNA synthesis at underreplicated regions. We speculated that such genomic regions are likely to hold stalled replication forks or post-replicative gaps, which become the substrate for DNA synthesis upon entry into mitosis. Thus, we addressed whether the translesion pathways for fork restart or post-replicative gap filling are required for unscheduled DNA synthesis in mitosis. Using genetics in the avian DT40 cell line, we provide evidence that unscheduled DNA synthesis in mitosis does not require the translesion synthesis scaffold factor Rev1 or PCNA ubiquitylation at K164, which serve to recruit translesion polymerases to stalled forks. In line with this finding, translesion polymerase η foci do not colocalize with TopBP1 or FANCD2 in mitosis. Taken together, we conclude that TopBP1 promotes unscheduled DNA synthesis in mitosis independently of the examined translesion polymerases.

Effects of copper on mitosis

Energy Technology Data Exchange (ETDEWEB)

Kostal, L

1971-01-01

The author deals with the effects of copper on mitosis. He found that a Cu concentration of 1 mg per liter is very toxic and strongly inhibits the course of mitosis in Vicia fabia. The effects of 0.5 mg and 0.25 mg Cu concentrations per liter were similar but a much weaker character.

The SUMO Pathway in Mitosis.

Science.gov (United States)

Mukhopadhyay, Debaditya; Dasso, Mary

2017-01-01

Mitosis is the stage of the cell cycle during which replicated chromosomes must be precisely divided to allow the formation of two daughter cells possessing equal genetic material. Much of the careful spatial and temporal organization of mitosis is maintained through post-translational modifications, such as phosphorylation and ubiquitination, of key cellular proteins. Here, we will review evidence that sumoylation, conjugation to the SUMO family of small ubiquitin-like modifiers, also serves essential regulatory roles during mitosis. We will discuss the basic biology of sumoylation, how the SUMO pathway has been implicated in particular mitotic functions, including chromosome condensation, centromere/kinetochore organization and cytokinesis, and what cellular proteins may be the targets underlying these phenomena.

Blocking Internalization of Phosphatidylethanolamine at Cleavage Furrow of Mitosis as a Novel Mechanism of Anti-Breast Cancer Strategy

National Research Council Canada - National Science Library

Cui, Zhen

2002-01-01

During the formation of cleavage furrow of mitosis, phosphatidylethanolamine (PE) flips from inner leaflet of the plasma membrane to the outer leaflet specifically in the furrow region near the contractile ring...

Blocking Internalization of Phosphatidylethanolamine at Cleavage Furrow of Mitosis as a Novel Mechanism of Anti-Breast-Cancer Strategy

National Research Council Canada - National Science Library

Cui, Zheng

2003-01-01

During the formation of cleavage furrow of mitosis, phosphatidylethanolamine (PE) flips from inner leaflet of the plasma membrane to the outer leaflet specifically in the furrow region near the contractile ring...

Mitosis.

Science.gov (United States)

Henderson, Paula

Cytology is the subject that is dealt with in this autoinstructional program. The process to be understood by secondary school students who are taking biology is mitosis. The material is presented to be adequate for achievers at the middle level. Knowledge of the structure of the DNA molecule and of the parts of the cell are considered as…

Regulation of mRNA translation during mitosis.

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Tanenbaum, Marvin E; Stern-Ginossar, Noam; Weissman, Jonathan S; Vale, Ronald D

2015-08-25

Passage through mitosis is driven by precisely-timed changes in transcriptional regulation and protein degradation. However, the importance of translational regulation during mitosis remains poorly understood. Here, using ribosome profiling, we find both a global translational repression and identified ~200 mRNAs that undergo specific translational regulation at mitotic entry. In contrast, few changes in mRNA abundance are observed, indicating that regulation of translation is the primary mechanism of modulating protein expression during mitosis. Interestingly, 91% of the mRNAs that undergo gene-specific regulation in mitosis are translationally repressed, rather than activated. One of the most pronounced translationally-repressed genes is Emi1, an inhibitor of the anaphase promoting complex (APC) which is degraded during mitosis. We show that full APC activation requires translational repression of Emi1 in addition to its degradation. These results identify gene-specific translational repression as a means of controlling the mitotic proteome, which may complement post-translational mechanisms for inactivating protein function.

Esters with imidazo [1,5-c] quinazoline-3,5-dione ring spectral characterization and quantum-mechanical modeling.

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Hęclik, K; Szyszkowska, A; Trzybiński, D; Woźniak, K; Klasek, A; Zarzyka, I

2017-04-01

1-phenyl-2H,6H-imidazo[1,5-c]quinazoline-3,5-dione reacts with ethyl bromoacetate under mild conditions to give 2-(ethoxycarbonylmethyl)-1-phenyl-6H-imidazo[1,5-c]quinazoline-3,5-dione (MEPIQ) and next 2,6-bis(ethoxycarbonylmethyl)-1-phenylimidazo[1,5-c]quinazoline-3,5-dione (BEPIQ). The products were isolated at high yield and identified on the basis of IR, 1 H- and 13 C-NMR, UV spectroscopy, and X-ray crystallography. Diester (BEPIQ) can be presented by 16 possible pair of enantiomers. Only one pair of them is the most stable and crystallizes which is shown crystallographic research. Based on quantum-mechanical modeling, with the use of DFT method, which conformers of mono- and diester and why they were formed was explained. It was calculated that 99.93% of the monoester (MEPIQ) is formed at position No. 2 and one pair of the monoester conformers, from six possible, has the largest share (51.63%). These results afforded to limit the number of diester conformers to eight. Unfortunately, the quantum-mechanical calculations performed that their shares are similar. Further quantum-mechanical modeling showed that conformers are able to undergo mutual transformations. As a result only one pair of diester conformers forms crystals. These conformers have substituents in trans position and these substituents are located parallel to imidazoquinazoline ring. This allows for the denser packing of the molecules in the unit cell.

Fresh WNT into the regulation of mitosis.

Science.gov (United States)

Stolz, Ailine; Bastians, Holger

2015-01-01

Canonical Wnt signaling triggering β-catenin-dependent gene expression contributes to cell cycle progression, in particular at the G1/S transition. Recently, however, it became clear that the cell cycle can also feed back on Wnt signaling at the G2/M transition. This is illustrated by the fact that mitosis-specific cyclin-dependent kinases can phosphorylate the Wnt co-receptor LRP6 to prime the pathway for incoming Wnt signals when cells enter mitosis. In addition, there is accumulating evidence that various Wnt pathway components might exert additional, Wnt-independent functions that are important for proper regulation of mitosis. The importance of Wnt pathways during mitosis was most recently enforced by the discovery of Wnt signaling contributing to the stabilization of proteins other than β-catenin, specifically at G2/M and during mitosis. This Wnt-mediated stabilization of proteins, now referred to as Wnt/STOP, might on one hand contribute to maintaining a critical cell size required for cell division and, on the other hand, for the faithful execution of mitosis itself. In fact, most recently we have shown that Wnt/STOP is required for ensuring proper microtubule dynamics within mitotic spindles, which is pivotal for accurate chromosome segregation and for the maintenance of euploidy.

Phosphorylation of the centrosomal protein, Cep169, by Cdk1 promotes its dissociation from centrosomes in mitosis.

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Mori, Yusuke; Inoue, Yoko; Taniyama, Yuki; Tanaka, Sayori; Terada, Yasuhiko

2015-12-25

Cep169 is a centrosomal protein conserved among vertebrates. In our previous reports, we showed that mammalian Cep169 interacts and collaborates with CDK5RAP2 to regulate microtubule (MT) dynamics and stabilization. Although Cep169 is required for MT regulation, its precise cellular function remains largely elusive. Here we show that Cep169 associates with centrosomes during interphase, but dissociates from these structures from the onset of mitosis, although CDK5RAP2 (Cep215) is continuously located at the centrosomes throughout cell cycle. Interestingly, treatment with purvalanol A, a Cdk1 inhibitor, nearly completely blocked the dissociation of Cep169 from centrosomes during mitosis. In addition, mass spectrometry analyses identified 7 phosphorylated residues of Cep169 corresponding to consensus phosphorylation sequence for Cdk1. These data suggest that the dissociation of Cep169 from centrosomes is controlled by Cdk1/Cyclin B during mitosis, and that Cep169 might regulate MT dynamics of mitotic spindle. Copyright © 2015 Elsevier Inc. All rights reserved.

p21 is Responsible for Ionizing Radiation-induced Bypass of Mitosis.

Science.gov (United States)

Zhang, Xu Rui; Liu, Yong Ai; Sun, Fang; Li, He; Lei, Su Wen; Wang, Ju Fang

2016-07-01

To explore the role of p21 in ionizing radiation-induced changes in protein levels during the G2/M transition and long-term G2 arrest. Protein expression levels were assessed by western blot in the human uveal melanoma 92-1 cells after treatment with ionizing radiation. Depletion of p21 was carried out by employing the siRNA technique. Cell cycle distribution was determined by flow cytometry combined with histone H3 phosphorylation at Ser28, an M-phase marker. Senescence was assessed by senescence- associated-β-galactosidase (SA-β-gal) staining combined with Ki67 staining, a cell proliferation marker. Accompanying increased p21, the protein levels of G2/M transition genes declined significantly in 92-1 cells irradiated with 5 Gy of X-rays. Furthermore, these irradiated cells were blocked at the G2 phase followed by cellular senescence. Depletion of p21 rescued radiation-induced G2 arrest as demonstrated by the upregulation of G2/M transition kinases, as well as the high expression of histone H3 phosphorylated at Ser28. Knockdown of p21 resulted in entry into mitosis of irradiated 92-1 cells. However, cells with serious DNA damage failed to undergo cytokinesis, leading to the accumulation of multinucleated cells. Our results indicated that p21 was responsible for the downregulation of G2/M transition regulatory proteins and the bypass of mitosis induced by irradiation. Downregulation of p21 by siRNA resulted in G2-arrested cells entering into mitosis with serious DNA damage. This is the first report on elucidating the role of p21 in the bypass of mitosis. Copyright © 2016 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.

Eco-efficient one-pot synthesis of quinazoline-2,4(1H,3H)-diones at room temperature in water.

Science.gov (United States)

Tian, Xin-Chuan; Huang, Xing; Wang, Dan; Gao, Feng

2014-01-01

An efficient one-pot synthesis of quinazoline-2,4(1H,3H)-diones was developed. First, the reactions of anthranilic acid derivatives with potassium cyanate afforded the corresponding urea derivatives. Then, cyclization of the urea derivatives with NaOH afforded the monosodium salts of benzoylene urea. Finally, HCl treatment afforded the desired products in near-quantitative yields. This is an eco-efficient method because all the reactions were carried out in water, and the desired products were obtained simply by filtration. The aqueous filtrate was the only waste generated from the reaction. We scaled up the reaction to 1 kg starting material, thus establishing an alternative approach for the green synthesis of quinazoline-2,4(1H,3H)-diones in the chemical and pharmaceutical industries.

Meiosis: An Overview of Key Differences from Mitosis

Science.gov (United States)

Ohkura, Hiroyuki

2015-01-01

Meiosis is the specialized cell division that generates gametes. In contrast to mitosis, molecular mechanisms and regulation of meiosis are much less understood. Meiosis shares mechanisms and regulation with mitosis in many aspects, but also has critical differences from mitosis. This review highlights these differences between meiosis and mitosis. Recent studies using various model systems revealed differences in a surprisingly wide range of aspects, including cell-cycle regulation, recombination, postrecombination events, spindle assembly, chromosome–spindle interaction, and chromosome segregation. Although a great degree of diversity can be found among organisms, meiosis-specific processes, and regulation are generally conserved. PMID:25605710

Role-Playing Mitosis.

Science.gov (United States)

Wyn, Mark A.; Stegink, Steven J.

2000-01-01

Introduces a role playing activity that actively engages students in the learning process of mitosis. Students play either chromosomes carrying information, or cells in the cell membrane. (Contains 11 references.) (Author/YDS)

Spatial Reorganization of the Endoplasmic Reticulum during Mitosis Relies on Mitotic Kinase Cyclin A in the Early Drosophila Embryo

Science.gov (United States)

Bergman, Zane J.; Mclaurin, Justin D.; Eritano, Anthony S.; Johnson, Brittany M.; Sims, Amanda Q.; Riggs, Blake

2015-01-01

Mitotic cyclin-dependent kinase with their cyclin partners (cyclin:Cdks) are the master regulators of cell cycle progression responsible for regulating a host of activities during mitosis. Nuclear mitotic events, including chromosome condensation and segregation have been directly linked to Cdk activity. However, the regulation and timing of cytoplasmic mitotic events by cyclin:Cdks is poorly understood. In order to examine these mitotic cytoplasmic events, we looked at the dramatic changes in the endoplasmic reticulum (ER) during mitosis in the early Drosophila embryo. The dynamic changes of the ER can be arrested in an interphase state by inhibition of either DNA or protein synthesis. Here we show that this block can be alleviated by micro-injection of Cyclin A (CycA) in which defined mitotic ER clusters gathered at the spindle poles. Conversely, micro-injection of Cyclin B (CycB) did not affect spatial reorganization of the ER, suggesting CycA possesses the ability to initiate mitotic ER events in the cytoplasm. Additionally, RNAi-mediated simultaneous inhibition of all 3 mitotic cyclins (A, B and B3) blocked spatial reorganization of the ER. Our results suggest that mitotic ER reorganization events rely on CycA and that control and timing of nuclear and cytoplasmic events during mitosis may be defined by release of CycA from the nucleus as a consequence of breakdown of the nuclear envelope. PMID:25689737

Synthesis and spectral studies of Pd(II) complexes with 2, 3-disubstituted quinazolin-(3H)-4-ones

International Nuclear Information System (INIS)

Prabhakar, B.; Lingaiah, P.; Laxima Reddy, K.

1991-01-01

A number of palladium(II) complexes of bidentate O-O and O-N donors, 2,3-disubstituted quinazoline-(3H)-4-ones, have been synthesized and characterized based on analytical, conductivity, magnetic, thermal, IR, electronic and PMR spectral data. The complexes of Pd(II) with ligands such as 2-(R)-3-(X)-substituted quinazoline-(3H)-4-ones, where R=methyl/phenyl and X=2'-hydroxybenzalimino (MHBQ/PHBQ), carboxymethyl (MCMQ/PCMQ), furfuralimino (MFQ/PFQ), acetamino (MAQ/PAQ), uramino (MUQ/PUQ) and thiouramino (MTUQ/PTUQ), yielded the complexes of the type [Pd(O-N) 2 ]Cl 2 and [Pd(O-O) 2 ]. The IR and PMR spectral data of the metal complexes indicate that MHQB, PHQB, MCMQ, and PCMQ act as uninegative bidentate ligands whereas MFQ, PFQ, MAQ, PAQ, MUQ, PUQ, MTUQ and PTUQ act as neutral bidentate ligands. The electronic spectral studies of these complexes indicate that they were square-planar geometry. (author). 23 refs., 2 tabs

Kinases Involved in Both Autophagy and Mitosis.

Science.gov (United States)

Li, Zhiyuan; Zhang, Xin

2017-08-31

Both mitosis and autophagy are highly regulated dynamic cellular processes and involve various phosphorylation events catalysed by kinases, which play vital roles in almost all physiological and pathological conditions. Mitosis is a key event during the cell cycle, in which the cell divides into two daughter cells. Autophagy is a process in which the cell digests its own cellular contents. Although autophagy regulation has mainly been studied in asynchronous cells, increasing evidence indicates that autophagy is in fact tightly regulated in mitosis. Here in this review, we will discuss kinases that were originally identified to be involved in only one of either mitosis or autophagy, but were later found to participate in both processes, such as CDKs (cyclin-dependent kinases), Aurora kinases, PLK-1 (polo-like kinase 1), BUB1 (budding uninhibited by benzimidazoles 1), MAPKs (mitogen-activated protein kinases), mTORC1 (mechanistic target of rapamycin complex 1), AMPK (AMP-activated protein kinase), PI3K (phosphoinositide-3 kinase) and protein kinase B (AKT). By focusing on kinases involved in both autophagy and mitosis, we will get a more comprehensive understanding about the reciprocal regulation between the two key cellular events, which will also shed light on their related therapeutic investigations.

Kinases Involved in Both Autophagy and Mitosis

Directory of Open Access Journals (Sweden)

Zhiyuan Li

2017-08-01

Full Text Available Both mitosis and autophagy are highly regulated dynamic cellular processes and involve various phosphorylation events catalysed by kinases, which play vital roles in almost all physiological and pathological conditions. Mitosis is a key event during the cell cycle, in which the cell divides into two daughter cells. Autophagy is a process in which the cell digests its own cellular contents. Although autophagy regulation has mainly been studied in asynchronous cells, increasing evidence indicates that autophagy is in fact tightly regulated in mitosis. Here in this review, we will discuss kinases that were originally identified to be involved in only one of either mitosis or autophagy, but were later found to participate in both processes, such as CDKs (cyclin-dependent kinases, Aurora kinases, PLK-1 (polo-like kinase 1, BUB1 (budding uninhibited by benzimidazoles 1, MAPKs (mitogen-activated protein kinases, mTORC1 (mechanistic target of rapamycin complex 1, AMPK (AMP-activated protein kinase, PI3K (phosphoinositide-3 kinase and protein kinase B (AKT. By focusing on kinases involved in both autophagy and mitosis, we will get a more comprehensive understanding about the reciprocal regulation between the two key cellular events, which will also shed light on their related therapeutic investigations.

Live imaging of mitosis in the developing mouse embryonic cortex.

Science.gov (United States)

Pilaz, Louis-Jan; Silver, Debra L

2014-06-04

Although of short duration, mitosis is a complex and dynamic multi-step process fundamental for development of organs including the brain. In the developing cerebral cortex, abnormal mitosis of neural progenitors can cause defects in brain size and function. Hence, there is a critical need for tools to understand the mechanisms of neural progenitor mitosis. Cortical development in rodents is an outstanding model for studying this process. Neural progenitor mitosis is commonly examined in fixed brain sections. This protocol will describe in detail an approach for live imaging of mitosis in ex vivo embryonic brain slices. We will describe the critical steps for this procedure, which include: brain extraction, brain embedding, vibratome sectioning of brain slices, staining and culturing of slices, and time-lapse imaging. We will then demonstrate and describe in detail how to perform post-acquisition analysis of mitosis. We include representative results from this assay using the vital dye Syto11, transgenic mice (histone H2B-EGFP and centrin-EGFP), and in utero electroporation (mCherry-α-tubulin). We will discuss how this procedure can be best optimized and how it can be modified for study of genetic regulation of mitosis. Live imaging of mitosis in brain slices is a flexible approach to assess the impact of age, anatomy, and genetic perturbation in a controlled environment, and to generate a large amount of data with high temporal and spatial resolution. Hence this protocol will complement existing tools for analysis of neural progenitor mitosis.

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

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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.

Poly(ADP-ribosyl)ation is recognized by ECT2 during mitosis.

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Li, Mo; Bian, Chunjing; Yu, Xiaochun

2014-01-01

Poly(ADP-ribosyl)ation is an unique posttranslational modification and required for spindle assembly and function during mitosis. However, the molecular mechanism of poly(ADP-ribose) (PAR) in mitosis remains elusive. Here, we show the evidence that PAR is recognized by ECT2, a key guanine nucleotide exchange factor in mitosis. The BRCT domain of ECT2 directly binds to PAR both in vitro and in vivo. We further found that α-tubulin is PARylated during mitosis. PARylation of α-tubulin is recognized by ECT2 and recruits ECT2 to mitotic spindle for completing mitosis. Taken together, our study reveals a novel mechanism by which PAR regulates mitosis.

Live Imaging of Mitosis in the Developing Mouse Embryonic Cortex

OpenAIRE

Pilaz, Louis-Jan; Silver, Debra L.

2014-01-01

Although of short duration, mitosis is a complex and dynamic multi-step process fundamental for development of organs including the brain. In the developing cerebral cortex, abnormal mitosis of neural progenitors can cause defects in brain size and function. Hence, there is a critical need for tools to understand the mechanisms of neural progenitor mitosis. Cortical development in rodents is an outstanding model for studying this process. Neural progenitor mitosis is commonly examined in fixe...

Imaging Mitosis in the Moss Physcomitrella patens.

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Yamada, Moé; Miki, Tomohiro; Goshima, Gohta

2016-01-01

At first glance, mitosis in plants looks quite different from that in animals. In fact, terrestrial plants have lost the centrosome during evolution, and the mitotic spindle is assembled independently of a strong microtubule organizing center. The phragmoplast is a plant-specific mitotic apparatus formed after anaphase, which expands centrifugally towards the cell cortex. However, the extent to which plant mitosis differs from that of animals at the level of the protein repertoire is uncertain, largely because of the difficulty in the identification and in vivo characterization of mitotic genes of plants. Here, we discuss protocols for mitosis imaging that can be combined with endogenous green fluorescent protein (GFP) tagging or conditional RNA interference (RNAi) in the moss Physcomitrella patens, which is an emergent model plant for cell and developmental biology. This system has potential for use in the high-throughput study of mitosis and other intracellular processes, as is being done with various animal cell lines.

Spectroscopic Investigations and DFT Calculations on 3-(Diacetylamino-2-ethyl-3H-quinazolin-4-one

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Yusuf Sert

2016-01-01

Full Text Available The theoretical and experimental vibrational frequencies of 3-(diacetylamino-2-ethyl-3H-quinazolin-4-one (2 were investigated. The experimental Laser-Raman spectrum (4000–100 cm−1 and FT-IR spectrum (4000–400 cm−1 of the newly synthesized compound were recorded in the solid phase. Both the theoretical vibrational frequencies and the optimized geometric parameters such as bond lengths and bond angles have for the first time been calculated using density functional theory (DFT/B3LYP and DFT/M06-2X quantum chemical methods with the 6-311++G(d,p basis set using Gaussian 03 software. The vibrational frequencies were assigned with the help of potential energy distribution (PED analysis using VEDA 4 software. The calculated vibrational frequencies and the optimized geometric parameters were found to be in good agreement with the corresponding reported experimental data. Also, the energies of the lowest unoccupied molecular orbital (LUMO, highest occupied molecular orbital (HOMO, and other related molecular energies for 3-(diacetylamino-2-ethyl-3H-quinazolin-4-one (2 have been investigated using the same computational methods.

Nucleocytoplasmic protein translocation during mitosis in the social amoebozoan Dictyostelium discoideum.

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O'Day, Danton H; Budniak, Aldona

2015-02-01

Mitosis is a fundamental and essential life process. It underlies the duplication and survival of all cells and, as a result, all eukaryotic organisms. Since uncontrolled mitosis is a dreaded component of many cancers, a full understanding of the process is critical. Evolution has led to the existence of three types of mitosis: closed, open, and semi-open. The significance of these different mitotic species, how they can lead to a full understanding of the critical events that underlie the asexual duplication of all cells, and how they may generate new insights into controlling unregulated cell division remains to be determined. The eukaryotic microbe Dictyostelium discoideum has proved to be a valuable biomedical model organism. While it appears to utilize closed mitosis, a review of the literature suggests that it possesses a form of mitosis that lies in the middle between truly open and fully closed mitosis-it utilizes a form of semi-open mitosis. Here, the nucleocytoplasmic translocation patterns of the proteins that have been studied during mitosis in the social amoebozoan D. discoideum are detailed followed by a discussion of how some of them provide support for the hypothesis of semi-open mitosis. © 2014 The Authors. Biological Reviews published by John Wiley & Sons Ltd on behalf of Cambridge Philosophical Society.

Promoters active in interphase are bookmarked during mitosis by ubiquitination

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Arora, Mansi; Zhang, Jie; Heine, George F.; Ozer, Gulcin; Liu, Hui-wen; Huang, Kun; Parvin, Jeffrey D.

2012-01-01

We analyzed modification of chromatin by ubiquitination in human cells and whether this mark changes through the cell cycle. HeLa cells were synchronized at different stages and regions of the genome with ubiquitinated chromatin were identified by affinity purification coupled with next-generation sequencing. During interphase, ubiquitin marked the chromatin on the transcribed regions of ∼70% of highly active genes and deposition of this mark was sensitive to transcriptional inhibition. Promoters of nearly half of the active genes were highly ubiquitinated specifically during mitosis. The ubiquitination at the coding regions in interphase but not at promoters during mitosis was enriched for ubH2B and dependent on the presence of RNF20. Ubiquitin labeling of both promoters during mitosis and transcribed regions during interphase, correlated with active histone marks H3K4me3 and H3K36me3 but not a repressive histone modification, H3K27me3. The high level of ubiquitination at the promoter chromatin during mitosis was transient and was removed within 2 h after the cells exited mitosis and entered the next cell cycle. These results reveal that the ubiquitination of promoter chromatin during mitosis is a bookmark identifying active genes during chromosomal condensation in mitosis, and we suggest that this process facilitates transcriptional reactivation post-mitosis. PMID:22941662

Tradescantia cytogenetic tests (root-tip mitosis, pollen mitosis, pollen mother-cell meiosis). A report of the US Environmental Protection Agency gene-tox program

Energy Technology Data Exchange (ETDEWEB)

Ma, T H

1982-01-01

3 kinds of cytogenetic tests for screening of environmental mutagens were established for Tradescantia, namely, root-tip mitosis, pollen mitosis, and pollen mother-cell meiosis (commonly referred to as the Tradescantia-micronucleus (Trad-MCN) test). All these tests are technically simple, inexpensive, and can yield reliable results in a relatively short time (36 to 72 h). The root-tip mitosis test is suitable only for liquid agents, while pollen mitosis is suitable for both liquid and gaseous agents. Pollen tube mitotic chromosomes are extremely sensitive to mutagens; therefore, they are good materials for detecting very low concentrations of mutagens. Both root-tip mitosis and pollen mitosis tests use chromosome and/or chromatid aberrations as end points for scoring. The Trad-MCN test is suitable for both liquid and gaseous agents. In addition, it is especially suitable for in situ monitoring of water and air pollutants. Of the 12 chemicals tested, 5-fluorouracil and 1,2-dibromoethane indicate that they are very potent mutagens based on the effective dosages used to produce a positive response. Sulfur dioxide, ethyl methanesulfonate, sodium azide, Phosdrin, and Bladex rank next in potency.

Differential Regulation of Smad3 and of the Type II Transforming Growth Factor-β Receptor in Mitosis: Implications for Signaling

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Hirschhorn, Tal; Barizilay, Lior; Smorodinsky, Nechama I.; Ehrlich, Marcelo

2012-01-01

The response to transforming growth factor-β (TGF-β) depends on cellular context. This context is changed in mitosis through selective inhibition of vesicle trafficking, reduction in cell volume and the activation of mitotic kinases. We hypothesized that these alterations in cell context may induce a differential regulation of Smads and TGF-β receptors. We tested this hypothesis in mesenchymal-like ovarian cancer cells, arrested (or not) in mitosis with 2-methoxyestradiol (2ME2). In mitosis, without TGF-β stimulation, Smad3 was phosphorylated at the C-terminus and linker regions and localized to the mitotic spindle. Phosphorylated Smad3 interacted with the negative regulators of Smad signaling, Smurf2 and Ski, and failed to induce a transcriptional response. Moreover, in cells arrested in mitosis, Smad3 levels were progressively reduced. These phosphorylations and reduction in the levels of Smad3 depended on ERK activation and Mps1 kinase activity, and were abrogated by increasing the volume of cells arrested in mitosis with hypotonic medium. Furthermore, an Mps1-dependent phosphorylation of GFP-Smad3 was also observed upon its over-expression in interphase cells, suggesting a mechanism of negative regulation which counters increases in Smad3 concentration. Arrest in mitosis also induced a block in the clathrin-mediated endocytosis of the type II TGF-β receptor (TβRII). Moreover, following the stimulation of mitotic cells with TGF-β, the proteasome-mediated attenuation of TGF-β receptor activity, the degradation and clearance of TβRII from the plasma membrane, and the clearance of the TGF-β ligand from the medium were compromised, and the C-terminus phosphorylation of Smad3 was prolonged. We propose that the reduction in Smad3 levels, its linker phosphorylation, and its association with negative regulators (observed in mitosis prior to ligand stimulation) represent a signal attenuating mechanism. This mechanism is balanced by the retention of active TGF

Students as "Humans Chromosomes" in Role-Playing Mitosis and Meiosis

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Chinnici, Joseph P.; Yue, Joyce W.; Torres, Kieron M.

2004-01-01

Students often find it challenging to understand mitosis and meiosis and determine their processes. To develop an easier way to understand these terms, students are asked to role-play mitosis and meiosis and students themselves act as human chromosomes, which help students to learn differences between mitosis and meiosis.

Genome accessibility is widely preserved and locally modulated during mitosis.

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Hsiung, Chris C-S; Morrissey, Christapher S; Udugama, Maheshi; Frank, Christopher L; Keller, Cheryl A; Baek, Songjoon; Giardine, Belinda; Crawford, Gregory E; Sung, Myong-Hee; Hardison, Ross C; Blobel, Gerd A

2015-02-01

Mitosis entails global alterations to chromosome structure and nuclear architecture, concomitant with transient silencing of transcription. How cells transmit transcriptional states through mitosis remains incompletely understood. While many nuclear factors dissociate from mitotic chromosomes, the observation that certain nuclear factors and chromatin features remain associated with individual loci during mitosis originated the hypothesis that such mitotically retained molecular signatures could provide transcriptional memory through mitosis. To understand the role of chromatin structure in mitotic memory, we performed the first genome-wide comparison of DNase I sensitivity of chromatin in mitosis and interphase, using a murine erythroblast model. Despite chromosome condensation during mitosis visible by microscopy, the landscape of chromatin accessibility at the macromolecular level is largely unaltered. However, mitotic chromatin accessibility is locally dynamic, with individual loci maintaining none, some, or all of their interphase accessibility. Mitotic reduction in accessibility occurs primarily within narrow, highly DNase hypersensitive sites that frequently coincide with transcription factor binding sites, whereas broader domains of moderate accessibility tend to be more stable. In mitosis, proximal promoters generally maintain their accessibility more strongly, whereas distal regulatory elements tend to lose accessibility. Large domains of DNA hypomethylation mark a subset of promoters that retain accessibility during mitosis and across many cell types in interphase. Erythroid transcription factor GATA1 exerts site-specific changes in interphase accessibility that are most pronounced at distal regulatory elements, but has little influence on mitotic accessibility. We conclude that features of open chromatin are remarkably stable through mitosis, but are modulated at the level of individual genes and regulatory elements. © 2015 Hsiung et al.; Published by

Spatial signals link exit from mitosis to spindle position.

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Falk, Jill Elaine; Tsuchiya, Dai; Verdaasdonk, Jolien; Lacefield, Soni; Bloom, Kerry; Amon, Angelika

2016-05-11

In budding yeast, if the spindle becomes mispositioned, cells prevent exit from mitosis by inhibiting the mitotic exit network (MEN). The MEN is a signaling cascade that localizes to spindle pole bodies (SPBs) and activates the phosphatase Cdc14. There are two competing models that explain MEN regulation by spindle position. In the 'zone model', exit from mitosis occurs when a MEN-bearing SPB enters the bud. The 'cMT-bud neck model' posits that cytoplasmic microtubule (cMT)-bud neck interactions prevent MEN activity. Here we find that 1) eliminating cMT- bud neck interactions does not trigger exit from mitosis and 2) loss of these interactions does not precede Cdc14 activation. Furthermore, using binucleate cells, we show that exit from mitosis occurs when one SPB enters the bud despite the presence of a mispositioned spindle. We conclude that exit from mitosis is triggered by a correctly positioned spindle rather than inhibited by improper spindle position.

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.

Deciphering the evolutionary history of open and closed mitosis.

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Sazer, Shelley; Lynch, Michael; Needleman, Daniel

2014-11-17

The origin of the nucleus at the prokaryote-to-eukaryote transition represents one of the most important events in the evolution of cellular organization. The nuclear envelope encircles the chromosomes in interphase and is a selectively permeable barrier between the nucleoplasm and cytoplasm and an organizational scaffold for the nucleus. It remains intact in the 'closed' mitosis of some yeasts, but loses its integrity in the 'open' mitosis of mammals. Instances of both types of mitosis within two evolutionary clades indicate multiple evolutionary transitions between open and closed mitosis, although the underlying genetic changes that influenced these transitions remain unknown. A survey of the diversity of mitotic nuclei that fall between these extremes is the starting point from which to determine the physiologically relevant characteristics distinguishing open from closed mitosis and to understand how they evolved and why they are retained in present-day organisms. The field is now poised to begin addressing these issues by defining and documenting patterns of mitotic nuclear variation within and among species and mapping them onto a phylogenic tree. Deciphering the evolutionary history of open and closed mitosis will complement cell biological and genetic approaches aimed at deciphering the fundamental organizational principles of the nucleus. Copyright © 2014 Elsevier Ltd. All rights reserved.

Rescue from replication stress during mitosis.

Science.gov (United States)

Fragkos, Michalis; Naim, Valeria

2017-04-03

Genomic instability is a hallmark of cancer and a common feature of human disorders, characterized by growth defects, neurodegeneration, cancer predisposition, and aging. Recent evidence has shown that DNA replication stress is a major driver of genomic instability and tumorigenesis. Cells can undergo mitosis with under-replicated DNA or unresolved DNA structures, and specific pathways are dedicated to resolving these structures during mitosis, suggesting that mitotic rescue from replication stress (MRRS) is a key process influencing genome stability and cellular homeostasis. Deregulation of MRRS following oncogene activation or loss-of-function of caretaker genes may be the cause of chromosomal aberrations that promote cancer initiation and progression. In this review, we discuss the causes and consequences of replication stress, focusing on its persistence in mitosis as well as the mechanisms and factors involved in its resolution, and the potential impact of incomplete replication or aberrant MRRS on tumorigenesis, aging and disease.

A QUANTUM MECHANICAL STUDY OF THE PROTONATION AND COVALENT HYDRATION OF QUINAZOLINE IN THE PRESENCE OF METAL CATIONS

Science.gov (United States)

We have investigated the protonation and reversible covalent hydration of quinazoline in the presence of Li+, Na+, and Ca2+ ions using ab initio quantum mechanical calculations at the MP2/6-31G**//HF/6-31G*level of theory. Proton affinities, enthalpies of hydration at 298.15K (DH...

Automated mitosis detection using texture, SIFT features and HMAX biologically inspired approach.

Science.gov (United States)

Irshad, Humayun; Jalali, Sepehr; Roux, Ludovic; Racoceanu, Daniel; Hwee, Lim Joo; Naour, Gilles Le; Capron, Frédérique

2013-01-01

According to Nottingham grading system, mitosis count in breast cancer histopathology is one of three components required for cancer grading and prognosis. Manual counting of mitosis is tedious and subject to considerable inter- and intra-reader variations. The aim is to investigate the various texture features and Hierarchical Model and X (HMAX) biologically inspired approach for mitosis detection using machine-learning techniques. We propose an approach that assists pathologists in automated mitosis detection and counting. The proposed method, which is based on the most favorable texture features combination, examines the separability between different channels of color space. Blue-ratio channel provides more discriminative information for mitosis detection in histopathological images. Co-occurrence features, run-length features, and Scale-invariant feature transform (SIFT) features were extracted and used in the classification of mitosis. Finally, a classification is performed to put the candidate patch either in the mitosis class or in the non-mitosis class. Three different classifiers have been evaluated: Decision tree, linear kernel Support Vector Machine (SVM), and non-linear kernel SVM. We also evaluate the performance of the proposed framework using the modified biologically inspired model of HMAX and compare the results with other feature extraction methods such as dense SIFT. The proposed method has been tested on Mitosis detection in breast cancer histological images (MITOS) dataset provided for an International Conference on Pattern Recognition (ICPR) 2012 contest. The proposed framework achieved 76% recall, 75% precision and 76% F-measure. Different frameworks for classification have been evaluated for mitosis detection. In future work, instead of regions, we intend to compute features on the results of mitosis contour segmentation and use them to improve detection and classification rate.

Synthesis and Biological Evaluation of Quinazoline-4-thiones

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Jarmila Kaustová

2003-11-01

Full Text Available Several 2,2-dimethyl-3-phenyl-1,2-dihydroquinazoline-4(3H-thiones and 2-methyl-3-phenylquinazoline-4(3H-thiones were synthesized and tested for their antimycobacterial, photosynthesis-inhibiting, and antialgal activity. Antimycobacterially active compounds were found among the 6-chloro substituted compounds. 6-Chloro-3-(4-isopropylphenyl-2-methylquinazoline-4(3H-thione exhibited higher activity than the isoniazid standard against Mycobacterium avium and M. kansasii. Most of the compounds possessed photosynthesis-inhibiting activity. 6-Chloro-2,2-dimethyl-3-phenyl-1,2-dihydroquinazoline-4(3H-thione and its 3´-chloro- and 3´,4´-dichloro analogs were most effective in the inhibition of oxygen evolution rate in spinach chloroplasts. Of compounds selected for toxicological screening, 6-chloro-3-(4-isopropylphenyl-2-methyl-quinazoline-4(3H-thione was the only one active in the brine shrimp bioassay.

Novel 2,3-Dihydro-1H-pyrrolo[3,2,1-ij]quinazolin-1-ones: Synthesis and Biological Evaluation

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Malose J. Mphahlele

2016-12-01

Full Text Available Herein we describe the synthesis and evaluation of a series of novel 2,3-dihydro-1H-pyrrolo[3,2,1-ij]quinazolin-1-ones for in vitro cytotoxicity against three human cancer cell lines as well as for potential antimalarial activity against the chloroquine-sensitive strain 3D7 of Plasmodium falciparum. The title compounds were prepared via PdCl2-mediated endo-dig cyclization of 2-aryl-8-(arylethynyl-6-bromo-2,3-dihydroquinazolin-4(1H-ones. The latter were prepared, in turn, via initial Sonogashira cross-coupling of 2-amino-5-bromo-3-iodobenzamide with aryl acetylenes followed by boric acid-mediated cyclocondensation of the intermediate 2-amino-3-(arylethynyl-5-bromobenzamides with benzaldehyde derivatives. The 2,3-dihydro-1H-pyrrolo[3,2,1-ij]quinazolin-1-ones 4a–k were evaluated for potential in vitro cytotoxicity against the breast (MCF-7, melanoma (B16 and endothelioma (sEnd.2 cell lines. All of the compounds except 4h and 4i were found to be inactive against the three cancer cell lines. Compound 4h substituted with a 4-methoxyphenyl and 4-fluorophenyl groups at the 3- and 5-positions was found to exhibit significant cytotoxicity against the three cancer cell lines. The presence of phenyl and 3-chlorophenyl groups at the 3- and 5-posiitons of the pyrroloquinazolinone 4i, on the other hand, resulted in significant cytotoxicity against vascular tumour endothelial cells (sEnd.2, but reduced activity against the melanoma (B16 and breast cancer (MCF-7 cells except at higher concentrations. The 2,3-dihydro-1H-pyrrolo[3,2,1-ij]quinazolin-1-ones 4a–l were found to be inactive against the chloroquine sensitive 3D7 strain of Plasmodium falciparum.

Automated mitosis detection using texture, SIFT features and HMAX biologically inspired approach

Directory of Open Access Journals (Sweden)

Humayun Irshad

2013-01-01

Full Text Available Context: According to Nottingham grading system, mitosis count in breast cancer histopathology is one of three components required for cancer grading and prognosis. Manual counting of mitosis is tedious and subject to considerable inter- and intra-reader variations. Aims: The aim is to investigate the various texture features and Hierarchical Model and X (HMAX biologically inspired approach for mitosis detection using machine-learning techniques. Materials and Methods: We propose an approach that assists pathologists in automated mitosis detection and counting. The proposed method, which is based on the most favorable texture features combination, examines the separability between different channels of color space. Blue-ratio channel provides more discriminative information for mitosis detection in histopathological images. Co-occurrence features, run-length features, and Scale-invariant feature transform (SIFT features were extracted and used in the classification of mitosis. Finally, a classification is performed to put the candidate patch either in the mitosis class or in the non-mitosis class. Three different classifiers have been evaluated: Decision tree, linear kernel Support Vector Machine (SVM, and non-linear kernel SVM. We also evaluate the performance of the proposed framework using the modified biologically inspired model of HMAX and compare the results with other feature extraction methods such as dense SIFT. Results: The proposed method has been tested on Mitosis detection in breast cancer histological images (MITOS dataset provided for an International Conference on Pattern Recognition (ICPR 2012 contest. The proposed framework achieved 76% recall, 75% precision and 76% F-measure. Conclusions: Different frameworks for classification have been evaluated for mitosis detection. In future work, instead of regions, we intend to compute features on the results of mitosis contour segmentation and use them to improve detection and

Linking abnormal mitosis to the acquisition of DNA damage

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Pellman, David

2012-01-01

Cellular defects that impair the fidelity of mitosis promote chromosome missegregation and aneuploidy. Increasing evidence reveals that errors in mitosis can also promote the direct and indirect acquisition of DNA damage and chromosome breaks. Consequently, deregulated cell division can devastate the integrity of the normal genome and unleash a variety of oncogenic stimuli that may promote transformation. Recent work has shed light on the mechanisms that link abnormal mitosis with the development of DNA damage, how cells respond to such affronts, and the potential impact on tumorigenesis. PMID:23229895

Antipsychotic potential of quinazoline ErbB1 inhibitors in a schizophrenia model established with neonatal hippocampal lesioning.

Science.gov (United States)

Mizuno, Makoto; Iwakura, Yuriko; Shibuya, Masako; Zheng, Yingjun; Eda, Takeyoshi; Kato, Taisuke; Takasu, Yohei; Nawa, Hiroyuki

2010-01-01

Hyper-signaling of the epidermal growth factor receptor family (ErbB) is implicated in the pathophysiology of schizophrenia. Various quinazoline inhibitors targeting ErbB1 or ErbB2 - 4 have been developed as anti-cancer agents and might be useful for antipsychotic treatment. In the present study, we used an animal model of schizophrenia established by neonatal hippocampal lesioning and evaluated the neurobehavioral consequences of ErbB1-inhibitor treatment. Subchronic administration of the ErbB1 inhibitor ZD1839 to the cerebroventricle of rats receiving neonatal hippocampal lesioning ameliorated deficits in prepulse inhibition as well as those in the latent inhibition of tone-dependent fear learning. There were no apparent adverse effects on basal learning scores or locomotor activity, however. The administration of other ErbB1 inhibitors, PD153035 and OSI-774, similarly attenuated the prepulse inhibition impairment of this animal model. In parallel, there were decreases in ErbB1 phosphorylation in animals treated with ErbB1 inhibitors. These results indicate an antipsychotic potential of quinazoline ErbB1 inhibitors. ErbB receptor tyrosine kinases may be novel therapeutic targets for schizophrenia or its related psychotic symptoms.

Mitosis-associated repression in development.

Science.gov (United States)

Esposito, Emilia; Lim, Bomyi; Guessous, Ghita; Falahati, Hanieh; Levine, Michael

2016-07-01

Transcriptional repression is a pervasive feature of animal development. Here, we employ live-imaging methods to visualize the Snail repressor, which establishes the boundary between the presumptive mesoderm and neurogenic ectoderm of early Drosophila embryos. Snail target enhancers were attached to an MS2 reporter gene, permitting detection of nascent transcripts in living embryos. The transgenes exhibit initially broad patterns of transcription but are refined by repression in the mesoderm following mitosis. These observations reveal a correlation between mitotic silencing and Snail repression. We propose that mitosis and other inherent discontinuities in transcription boost the activities of sequence-specific repressors, such as Snail. © 2016 Esposito et al.; Published by Cold Spring Harbor Laboratory Press.

Phosphorylation of CPAP by Aurora-A Maintains Spindle Pole Integrity during Mitosis

OpenAIRE

En-Ju Chou; Liang-Yi Hung; Chieh-Ju C. Tang; Wen-Bin Hsu; Hsin-Yi Wu; Pao-Chi Liao; Tang K. Tang

2016-01-01

CPAP is required for centriole elongation during S/G2 phase, but the role of CPAP in mitosis is incompletely understood. Here, we show that CPAP maintains spindle pole integrity through its phosphorylation by Aurora-A during mitosis. Depletion of CPAP induced a prolonged delay in mitosis, pericentriolar material (PCM) dispersion, and multiple mitotic abnormalities. Further studies demonstrated that CPAP directly interacts with and is phosphorylated by Aurora-A at serine 467 during mitosis. In...

Mitosis-specific phosphorylation of PML at T409 regulates spindle checkpoint.

Science.gov (United States)

Jin, J; Liu, J

2016-08-31

During mitosis, Promyelocytic leukemia nuclear bodies (PML NBs) change dramatically in morphology and composition, but little is known about function of PML in mitosis. Here, we show that PML is phosphorylated at T409 (PML p409) in a mitosis-specific manner. More importantly, PML p409 contributes to maintain the duration of pro-metaphase and regulates spindle checkpoint. Deficient PML p409 caused a shortening of pro-metaphase and challenged the nocodazole-triggered mitotic arrest. T409A mutation led to a higher frequency of misaligned chromosomes on metaphase plate, and subsequently death in late mitosis. In addition, inhibition of PML p409 repressed growth of tumor cells, suggesting that PML p409 is a potential target for cancer therapy. Collectively, our study demonstrated an important phosphorylated site of PML, which contributed to explore the role of PML in mitosis.

Identification of quinazoline based inhibitors of IRAK4 for the treatment of inflammation

Energy Technology Data Exchange (ETDEWEB)

Smith, Graham F.; Altman, Michael D.; Andresen, Brian; Baker, James; Brubaker, Jason D.; Chen, Hongmin; Chen, Yiping; Childers, Matthew; Donofrio, Anthony; Ferguson, Heidi; Fischer, Christian; Fischmann, Thierry O.; Gibeau, Craig; Hicks, Alexander; Jin, Sue; Kattar, Sam; Kleinschek, Melanie A.; Leccese, Erica; Lesburg, Charles; Li, Chaomin; Lim, Jongwon; Liu, Duan; Maclean, John K.F.; Mansoor, Faruk; Moy, Lilly Y.; Mulrooney, Erin F.; Necheva, Antoaneta S.; Presland, Jeremy; Rakhilina, Larissa; Yang, Ruojing; Torres, Luis; Zhang-Hoover, Jie; Northrup, Alan (Merck); (Oncorus); (Theravance Biopharma); (AstraZeneca); (Blueprint Medicines)

2017-06-01

Interleukin-1 receptor associated kinase 4 (IRAK4) has been implicated in IL-1R and TLR based signaling. Therefore selective inhibition of the kinase activity of this protein represents an attractive target for the treatment of inflammatory diseases. Medicinal chemistry optimization of high throughput screening (HTS) hits with the help of structure based drug design led to the identification of orally-bioavailable quinazoline based IRAK4 inhibitors with excellent pharmacokinetic profile and kinase selectivity. These highly selective IRAK4 compounds show activity in vivo via oral dosing in a TLR7 driven model of inflammation.

Cholesterol is essential for mitosis progression and its deficiency induces polyploid cell formation

International Nuclear Information System (INIS)

Fernandez, Carlos; Lobo, Maria del Val T.; Gomez-Coronado, Diego; Lasuncion, Miguel A.

2004-01-01

As an essential component of mammalian cell membranes, cells require cholesterol for proliferation, which is either obtained from plasma lipoproteins or synthesized intracellularly from acetyl-CoA. In addition to cholesterol, other non-sterol mevalonate derivatives are necessary for DNA synthesis, such as the phosphorylated forms of isopentane, farnesol, geranylgeraniol, and dolichol. The aim of the present study was to elucidate the role of cholesterol in mitosis. For this, human leukemia cells (HL-60) were incubated in a cholesterol-free medium and treated with SKF 104976, which inhibits cholesterol biosynthesis by blocking sterol 14α-demethylase, and the expression of relevant cyclins in the different phases of the cell cycle was analyzed by flow cytometry. Prolonged cholesterol starvation induced the inhibition of cytokinesis and the formation of polyploid cells, which were multinucleated and had mitotic aberrations. Supplementing the medium with cholesterol completely abolished these effects, demonstrating they were specifically due to cholesterol deficiency. This is the first evidence that cholesterol is essential for mitosis completion and that, in the absence of cholesterol, the cells fail to undergo cytokinesis, entered G1 phase at higher DNA ploidy (tetraploidy), and then progressed through S (rereplication) into G2, generating polyploid cells

Regulatory functional territory of PLK-1 and their substrates beyond mitosis.

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Kumar, Shiv; Sharma, Garima; Chakraborty, Chiranjib; Sharma, Ashish Ranjan; Kim, Jaebong

2017-06-06

Polo-like kinase 1 (PLK-1) is a well-known (Ser/Thr) mitotic protein kinase and is considered as a proto-oncogene. As hyper-activation of PLK-1 is broadly associated with poor prognosis and cancer progression, it is one of the most extensively studied mitotic kinases. During mitosis, PLK-1 regulates various cell cycle events, such as spindle pole maturation, chromosome segregation and cytokinesis. However, studies have demonstrated that the role of PLK-1 is not only restricted to mitosis, but PLK-1 can also regulate other vital events beyond mitosis, including transcription, translation, ciliogenesis, checkpoint adaptation and recovery, apoptosis, chromosomes dynamics etc. Recent reviews have tried to define the regulatory role of PLK-1 during mitosis progression and tumorigenesis, but its' functional role beyond mitosis is still largely unexplored. PLK-1 can regulate the activity of many proteins that work outside of its conventional territory. The dysregulation of these proteins can cause diseases such as Alzheimer's disease, tumorigenesis etc. and may also lead to drug resistance. Thus, in this review, we discussed the versatile role of PLK-1 and tried to collect data to validate its' functional role in cell cycle regulation apart from mitosis.

A hyperactive transcriptional state marks genome reactivation at the mitosis-G1 transition.

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Hsiung, Chris C-S; Bartman, Caroline R; Huang, Peng; Ginart, Paul; Stonestrom, Aaron J; Keller, Cheryl A; Face, Carolyne; Jahn, Kristen S; Evans, Perry; Sankaranarayanan, Laavanya; Giardine, Belinda; Hardison, Ross C; Raj, Arjun; Blobel, Gerd A

2016-06-15

During mitosis, RNA polymerase II (Pol II) and many transcription factors dissociate from chromatin, and transcription ceases globally. Transcription is known to restart in bulk by telophase, but whether de novo transcription at the mitosis-G1 transition is in any way distinct from later in interphase remains unknown. We tracked Pol II occupancy genome-wide in mammalian cells progressing from mitosis through late G1. Unexpectedly, during the earliest rounds of transcription at the mitosis-G1 transition, ∼50% of active genes and distal enhancers exhibit a spike in transcription, exceeding levels observed later in G1 phase. Enhancer-promoter chromatin contacts are depleted during mitosis and restored rapidly upon G1 entry but do not spike. Of the chromatin-associated features examined, histone H3 Lys27 acetylation levels at individual loci in mitosis best predict the mitosis-G1 transcriptional spike. Single-molecule RNA imaging supports that the mitosis-G1 transcriptional spike can constitute the maximum transcriptional activity per DNA copy throughout the cell division cycle. The transcriptional spike occurs heterogeneously and propagates to cell-to-cell differences in mature mRNA expression. Our results raise the possibility that passage through the mitosis-G1 transition might predispose cells to diverge in gene expression states. © 2016 Hsiung et al.; Published by Cold Spring Harbor Laboratory Press.

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

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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.

DNA-damage response during mitosis induces whole-chromosome missegregation.

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Bakhoum, Samuel F; Kabeche, Lilian; Murnane, John P; Zaki, Bassem I; Compton, Duane A

2014-11-01

Many cancers display both structural (s-CIN) and numerical (w-CIN) chromosomal instabilities. Defective chromosome segregation during mitosis has been shown to cause DNA damage that induces structural rearrangements of chromosomes (s-CIN). In contrast, whether DNA damage can disrupt mitotic processes to generate whole chromosomal instability (w-CIN) is unknown. Here, we show that activation of the DNA-damage response (DDR) during mitosis selectively stabilizes kinetochore-microtubule (k-MT) attachments to chromosomes through Aurora-A and PLK1 kinases, thereby increasing the frequency of lagging chromosomes during anaphase. Inhibition of DDR proteins, ATM or CHK2, abolishes the effect of DNA damage on k-MTs and chromosome segregation, whereas activation of the DDR in the absence of DNA damage is sufficient to induce chromosome segregation errors. Finally, inhibiting the DDR during mitosis in cancer cells with persistent DNA damage suppresses inherent chromosome segregation defects. Thus, the DDR during mitosis inappropriately stabilizes k-MTs, creating a link between s-CIN and w-CIN. The genome-protective role of the DDR depends on its ability to delay cell division until damaged DNA can be fully repaired. Here, we show that when DNA damage is induced during mitosis, the DDR unexpectedly induces errors in the segregation of entire chromosomes, thus linking structural and numerical chromosomal instabilities. ©2014 American Association for Cancer Research.

Action of mercury in plant mitosis II

Energy Technology Data Exchange (ETDEWEB)

Lorente, R

1972-01-01

The cytological abnormalities induced by mercurochrome on mitosis and meiosis of Allium cepa are studied and the capacity of the chemical agent to induce c-mitosis is shown. Inhibition of the cytokinetic process as well as alterations of the nucleoli and pollen-mother cells (from pachytene to division II) have also been observed. These cytological effects may be ascribed to the affinity of the mercurial compounds for the thyolic groups existing in the nucleoproteins and protoplasmic proteins, with the subsequent inhibitory effect on the enzymatic mechanisms.

Foci of cyclin A2 interact with actin and RhoA in mitosis.

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Loukil, Abdelhalim; Izard, Fanny; Georgieva, Mariya; Mashayekhan, Shaereh; Blanchard, Jean-Marie; Parmeggiani, Andrea; Peter, Marion

2016-06-09

Cyclin A2 is a key player in the regulation of the cell cycle. Its degradation in mid-mitosis depends primarily on the ubiquitin-proteasome system (UPS), while autophagy also contributes. However, a fraction of cyclin A2 persists beyond metaphase. In this work, we focus on cyclin A2-rich foci detected in mitosis by high resolution imaging and analyse their movements. We demonstrate that cyclin A2 interacts with actin and RhoA during mitosis, and that cyclin A2 depletion induces a dramatic decrease in active RhoA in mitosis. Our data suggest cyclin A2 participation in RhoA activation in late mitosis.

Characterization of mitosis-specific phosphorylation of tumor-associated microtubule-associated protein.

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Hong, Kyung Uk; Kim, Hyun-Jun; Bae, Chang-Dae; Park, Joobae

2009-11-30

Tumor-associated microtubule-associated protein (TMAP), also known as cytoskeleton associated protein 2 (CKAP2), has been recently shown to be involved in the assembly and maintenance of mitotic spindle and also plays an essential role in maintaining the fidelity of chromosome segregation during mitosis. We have previously reported that TMAP is phosphorylated at multiple residues specifically during mitosis, and characterized the mechanism and functional importance of phosphorylation at one of the mitosis-specific phosphorylation residues (i.e., Thr-622). However, the phosphorylation events at the remaining mitotic phosphorylation sites of TMAP have not been fully characterized in detail. Here, we report on generation and characterization of phosphorylated Thr-578- and phosphorylated Thr-596-specific antibodies. Using the antibodies, we show that phosphorylation of TMAP at Thr-578 and Thr-596 indeed occurs specifically during mitosis. Immunofluorescent staining using the antibodies shows that these residues become phosphorylated starting at prophase and then become rapidly dephosphorylated soon after initiation of anaphase. Subtle differences in the kinetics of phosphorylation between Thr-578 and Thr-596 imply that they may be under different mechanisms of phosphorylation during mitosis. Unlike the phosphorylation-deficient mutant form for Thr-622, the mutant in which both Thr-578 and Thr-596 had been mutated to alanines did not induce significant delay in progression of mitosis. These results show that the majority of mitosis-specific phosphorylation of TMAP is limited to pre-anaphase stages and suggest that the multiple phosphorylation may not act in concert but serve diverse functions.

Autophagic flux is highly active in early mitosis and differentially regulated throughout the cell cycle.

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Li, Zhiyuan; Ji, Xinmiao; Wang, Dongmei; Liu, Juanjuan; Zhang, Xin

2016-06-28

Mitosis is a fast process that involves dramatic cellular remodeling and has a high energy demand. Whether autophagy is active or inactive during the early stages of mitosis in a naturally dividing cell is still debated. Here we aimed to use multiple assays to resolve this apparent discrepancy. Although the LC3 puncta number was reduced in mitosis, the four different cell lines we tested all have active autophagic flux in both interphase and mitosis. In addition, the autophagic flux was highly active in nocodazole-induced, double-thymidine synchronization released as well as naturally occurring mitosis in HeLa cells. Multiple autophagy proteins are upregulated in mitosis and the increased Beclin-1 level likely contributes to the active autophagic flux in early mitosis. It is interesting that although the autophagic flux is active throughout the cell cycle, early mitosis and S phase have relatively higher autophagic flux than G1 and late G2 phases, which might be helpful to degrade the damaged organelles and provide energy during S phase and mitosis.

The Functional Role of TopBP1 in DNA Maintenance at Mitosis

DEFF Research Database (Denmark)

Pedersen, Rune Troelsgaard

When cells traverse mitosis, genome integrity of the emerging daughter cells is dependent on replication of the entire genome during the preceding S-phase and accurate chromosome segregation in mitosis. Replication stress may cause cells to enter mitosis with underreplicated loci, consisting...... can lead to anaphase bridges that impair accurate chromosome segregation. The recent decade featured many advances in our understanding of how cells cope with underreplicated loci in mitosis. A major advance was the description of ultra-fine anaphase bridges (UFBs), a class of anaphase bridges...... established Saccharomyces cerevisiae as a model organism to study anaphase bridges, and we identified Dpb11/TopBP1 as a novel UFB-associated protein in yeast and avian DT40 cells, respectively. TopBP1 localized to confined areas on replication-stress induced UFBs. Upon onset of mitosis we observed a burst...

Aurora-A regulates MCRS1 function during mitosis.

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Meunier, Sylvain; Timón, Krystal; Vernos, Isabelle

2016-07-02

The mitotic spindle is made of microtubules (MTs) nucleated through different pathways involving the centrosomes, the chromosomes or the walls of pre-existing MTs. MCRS1 is a RanGTP target that specifically associates with the chromosome-driven MTs protecting them from MT depolymerases. MCRS1 is also needed for the control of kinetochore fiber (K-fiber) MT minus-ends dynamics in metaphase. Here, we investigated the regulation of MCRS1 activity in M-phase. We show that MCRS1 is phosphorylated by the Aurora-A kinase in mitosis on Ser35/36. Although this phosphorylation has no role on MCRS1 localization to chromosomal MTs and K-fiber minus-ends, we show that it regulates MCRS1 activity in mitosis. We conclude that Aurora-A activity is particularly important in the tuning of K-fiber minus-ends dynamics in mitosis.

Using a Case-Study Article to Effectively Introduce Mitosis

Science.gov (United States)

Van Hoewyk, Doug

2007-01-01

Community college students in a nonmajors biology class are introduced to mitosis by reading a case-study article that allows them to gauge how many times various parts of their bodies have been regenerated. The case-study article allows students to develop a conceptual framework of the cell cycle prior to a lecture on mitosis. (Contains 1 figure.)

ERK5 pathway regulates the phosphorylation of tumour suppressor hDlg during mitosis

Energy Technology Data Exchange (ETDEWEB)

Inesta-Vaquera, Francisco A. [Departamento de Inmunologia y Oncologia, Centro Nacional de Biotecnologia-CSIC, Campus de Cantoblanco-UAM, 28049 Madrid (Spain); Campbell, David G.; Arthur, J. Simon C. [MRC Protein Phosphorylation Unit, Sir James Black Building, School of Life Sciences, University of Dundee, Dundee DD1 5EH (United Kingdom); Cuenda, Ana, E-mail: acuenda@cnb.csic.es [Departamento de Inmunologia y Oncologia, Centro Nacional de Biotecnologia-CSIC, Campus de Cantoblanco-UAM, 28049 Madrid (Spain)

2010-08-13

Research highlights: {yields} hDlg is phosphorylated during mitosis in multiple residues. {yields} Prospho-hDlg is excluded from the midbody during mitosis. {yields} hDlg is not phosphorylated by p38{gamma} or JNK1/2 during mitosis. {yields} ERK5 pathway mediates hDlg phosphorylation in mitosis. -- Abstract: Human disc-large (hDlg) is a scaffold protein critical for the maintenance of cell polarity and adhesion. hDlg is thought to be a tumour suppressor that regulates the cell cycle and proliferation. However, the mechanism and pathways involved in hDlg regulation during these processes is still unclear. Here we report that hDlg is phosphorylated during mitosis, and we establish the identity of at least three residues phosphorylated in hDlg; some are previously unreported. Phosphorylation affects hDlg localisation excluding it from the contact point between the two daughter cells. Our results reveal a previously unreported pathway for hDlg phosphorylation in mitosis and show that ERK5 pathway mediates hDlg cell cycle dependent phosphorylation. This is likely to have important implications in the correct timely mitotic entry and mitosis progression.

ERK5 pathway regulates the phosphorylation of tumour suppressor hDlg during mitosis

International Nuclear Information System (INIS)

Inesta-Vaquera, Francisco A.; Campbell, David G.; Arthur, J. Simon C.; Cuenda, Ana

2010-01-01

Research highlights: → hDlg is phosphorylated during mitosis in multiple residues. → Prospho-hDlg is excluded from the midbody during mitosis. → hDlg is not phosphorylated by p38γ or JNK1/2 during mitosis. → ERK5 pathway mediates hDlg phosphorylation in mitosis. -- Abstract: Human disc-large (hDlg) is a scaffold protein critical for the maintenance of cell polarity and adhesion. hDlg is thought to be a tumour suppressor that regulates the cell cycle and proliferation. However, the mechanism and pathways involved in hDlg regulation during these processes is still unclear. Here we report that hDlg is phosphorylated during mitosis, and we establish the identity of at least three residues phosphorylated in hDlg; some are previously unreported. Phosphorylation affects hDlg localisation excluding it from the contact point between the two daughter cells. Our results reveal a previously unreported pathway for hDlg phosphorylation in mitosis and show that ERK5 pathway mediates hDlg cell cycle dependent phosphorylation. This is likely to have important implications in the correct timely mitotic entry and mitosis progression.

Positive Feedback Keeps Duration of Mitosis Temporally Insulated from Upstream Cell-Cycle Events.

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Araujo, Ana Rita; Gelens, Lendert; Sheriff, Rahuman S M; Santos, Silvia D M

2016-10-20

Cell division is characterized by a sequence of events by which a cell gives rise to two daughter cells. Quantitative measurements of cell-cycle dynamics in single cells showed that despite variability in G1-, S-, and G2 phases, duration of mitosis is short and remarkably constant. Surprisingly, there is no correlation between cell-cycle length and mitotic duration, suggesting that mitosis is temporally insulated from variability in earlier cell-cycle phases. By combining live cell imaging and computational modeling, we showed that positive feedback is the molecular mechanism underlying the temporal insulation of mitosis. Perturbing positive feedback gave rise to a sluggish, variable entry and progression through mitosis and uncoupled duration of mitosis from variability in cell cycle length. We show that positive feedback is important to keep mitosis short, constant, and temporally insulated and anticipate it might be a commonly used regulatory strategy to create modularity in other biological systems. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Bora and Aurora-A continue to activate Plk1 in mitosis.

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Bruinsma, Wytse; Macurek, Libor; Freire, Raimundo; Lindqvist, Arne; Medema, René H

2014-02-15

Polo-like kinase-1 (Plk1) is required for proper cell division. Activation of Plk1 requires phosphorylation on a conserved threonine in the T-loop of the kinase domain (T210). Plk1 is first phosphorylated on T210 in G2 phase by the kinase Aurora-A, in concert with its cofactor Bora. However, Bora was shown to be degraded prior to entry into mitosis, and it is currently unclear how Plk1 activity is sustained in mitosis. Here we show that the Bora-Aurora-A complex remains the major activator of Plk1 in mitosis. We show that a small amount of Aurora-A activity is sufficient to phosphorylate and activate Plk1 in mitosis. In addition, a fraction of Bora is retained in mitosis, which is essential for continued Aurora-A-dependent T210 phosphorylation of Plk1. We find that once Plk1 is activated, minimal amounts of the Bora-Aurora-A complex are sufficient to sustain Plk1 activity. Thus, the activation of Plk1 by Aurora-A may function as a bistable switch; highly sensitive to inhibition of Aurora-A in its initial activation, but refractory to fluctuations in Aurora-A activity once Plk1 is fully activated. This provides a cell with robust Plk1 activity once it has committed to mitosis.

The Biochemistry of Mitosis

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Wieser, Samuel; Pines, Jonathon

2015-01-01

In this article, we will discuss the biochemistry of mitosis in eukaryotic cells. We will focus on conserved principles that, importantly, are adapted to the biology of the organism. It is vital to bear in mind that the structural requirements for division in a rapidly dividing syncytial Drosophila embryo, for example, are markedly different from those in a unicellular yeast cell. Nevertheless, division in both systems is driven by conserved modules of antagonistic protein kinases and phosphatases, underpinned by ubiquitin-mediated proteolysis, which create molecular switches to drive each stage of division forward. These conserved control modules combine with the self-organizing properties of the subcellular architecture to meet the specific needs of the cell. Our discussion will draw on discoveries in several model systems that have been important in the long history of research on mitosis, and we will try to point out those principles that appear to apply to all cells, compared with those in which the biochemistry has been specifically adapted in a particular organism. PMID:25663668

Cancer: Mitosis Run Amok

Science.gov (United States)

Science Scope, 2005

2005-01-01

Virtually every student knows someone who has battled cancer. It is a topic that is of great interest to many students because of their personal connection to the subject. Mitosis is an important topic in a middle school unit on cells and cell processes (National Science Standards, Grades 5?8: Life Sciences: Content Standard C). Studying cancer…

Prolonged Mitosis of Neural Progenitors Alters Cell Fate in the Developing Brain.

Science.gov (United States)

Pilaz, Louis-Jan; McMahon, John J; Miller, Emily E; Lennox, Ashley L; Suzuki, Aussie; Salmon, Edward; Silver, Debra L

2016-01-06

Embryonic neocortical development depends on balanced production of progenitors and neurons. Genetic mutations disrupting progenitor mitosis frequently impair neurogenesis; however, the link between altered mitosis and cell fate remains poorly understood. Here we demonstrate that prolonged mitosis of radial glial progenitors directly alters neuronal fate specification and progeny viability. Live imaging of progenitors from a neurogenesis mutant, Magoh(+/-), reveals that mitotic delay significantly correlates with preferential production of neurons instead of progenitors, as well as apoptotic progeny. Independently, two pharmacological approaches reveal a causal relationship between mitotic delay and progeny fate. As mitotic duration increases, progenitors produce substantially more apoptotic progeny or neurons. We show that apoptosis, but not differentiation, is p53 dependent, demonstrating that these are distinct outcomes of mitotic delay. Together our findings reveal that prolonged mitosis is sufficient to alter fates of radial glia progeny and define a new paradigm to understand how mitosis perturbations underlie brain size disorders such as microcephaly. Copyright © 2016 Elsevier Inc. All rights reserved.

(E-3-Propoxymethylidene-2,3-dihydro-1H-pyrrolo[2,1-b]quinazolin-9-one monohydrate

Directory of Open Access Journals (Sweden)

Burkhon Zh Elmuradov

2010-05-01

Full Text Available The title compound, C15H16N2O2·H2O, was synthesized via the alkylation of 3-hydroxymethylidene-2,3-dihydro-1H-pyrrolo[2,1-b]quinazolin-9-one with n-propyl iodide in the presence of sodium hydroxide. The organic molecule and the water molecule both lie on a crystallographic mirror plane. In the crystal structure, intermolecular O—H...O and O—H...N hydrogen bonds link the components into extended chains along [100].

O-Linked N-Acetylglucosamine Transiently Elevates in HeLa Cells during Mitosis

Directory of Open Access Journals (Sweden)

Viktória Fisi

2018-05-01

Full Text Available O-linked N-acetylglucosamine (O-GlcNAc is a dynamic post-translational modification of serine and threonine residues on nuclear and cytoplasmic proteins. O-GlcNAc modification influences many cellular mechanisms, including carbohydrate metabolism, signal transduction and protein degradation. Multiple studies also showed that cell cycle might be modulated by O-GlcNAc. Although the role of O-GlcNAc in the regulation of some cell cycle processes such as mitotic spindle organization or histone phosphorylation is well established, the general behaviour of O-GlcNAc regulation during cell cycle is still controversial. In this study, we analysed the dynamic changes of overall O-GlcNAc levels in HeLa cells using double thymidine block. O-GlcNAc levels in G1, S, G2 and M phase were measured. We observed that O-GlcNAc levels are significantly increased during mitosis in comparison to the other cell cycle phases. However, this change could only be detected when mitotic cells were enriched by harvesting round shaped cells from the G2/M fraction of the synchronized cells. Our data verify that O-GlcNAc is elevated during mitosis, but also emphasize that O-GlcNAc levels can significantly change in a short period of time. Thus, selection and collection of cells at specific cell-cycle checkpoints is a challenging, but necessary requirement for O-GlcNAc studies.

Parkin Regulates Mitosis and Genomic Stability through Cdc20/Cdh1.

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Lee, Seung Baek; Kim, Jung Jin; Nam, Hyun-Ja; Gao, Bowen; Yin, Ping; Qin, Bo; Yi, Sang-Yeop; Ham, Hyoungjun; Evans, Debra; Kim, Sun-Hyun; Zhang, Jun; Deng, Min; Liu, Tongzheng; Zhang, Haoxing; Billadeau, Daniel D; Wang, Liewei; Giaime, Emilie; Shen, Jie; Pang, Yuan-Ping; Jen, Jin; van Deursen, Jan M; Lou, Zhenkun

2015-10-01

Mutations in the E3 ubiquitin ligase Parkin have been linked to familial Parkinson's disease. Parkin has also been implicated in mitosis through mechanisms that are unclear. Here we show that Parkin interacts with anaphase promoting complex/cyclosome (APC/C) coactivators Cdc20 and Cdh1 to mediate the degradation of several key mitotic regulators independent of APC/C. We demonstrate that ordered progression through mitosis is orchestrated by two distinct E3 ligases through the shared use of Cdc20 and Cdh1. Furthermore, Parkin is phosphorylated and activated by polo-like kinase 1 (Plk1) during mitosis. Parkin deficiency results in overexpression of its substrates, mitotic defects, genomic instability, and tumorigenesis. These results suggest that the Parkin-Cdc20/Cdh1 complex is an important regulator of mitosis. Copyright © 2015 Elsevier Inc. All rights reserved.

Comparative proteomics of mitosis and meiosis in Saccharomyces cerevisiae.

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Kumar, Ravinder; Dhali, Snigdha; Srikanth, Rapole; Ghosh, Santanu Kumar; Srivastava, Sanjeeva

2014-09-23

Precise and timely segregation of genetic material and conservation of ploidy are the two foremost requirements for survival of a eukaryotic organism. Two highly regulated cell division processes, namely mitosis and meiosis are central to achieve this objective. The modes of chromosome segregation are distinct in these two processes that generate progeny cells of equal ploidy and half the ploidy in mitosis and meiosis, respectively. Additionally, the nutritional requirement and intracellular processing of biological cue also differ in these two processes. From this, it can be envisaged that proteome of mitotic and meiotic cells will differ significantly. Therefore, identification of proteins that differ in their level of expression between mitosis and meiosis would further reveal the mechanistic detail of these processes. In the present study, we have investigated the protein expression profile of mitosis and meiosis by comparing proteome of budding yeast cultures arrested at mitotic metaphase and metaphase-I of meiosis using proteomic approach. Approximately 1000 and 2000 protein spots were visualized on 2-DE and 2D-DIGE gels respectively, out of which 14 protein spots were significant in 2-DE and 22 in 2D-DIGE (pmitosis, an up-regulation of actin cytoskeleton and its negative regulator occurs in meiosis. Mitosis and meiosis are two different types of cell division cycles with entirely different outcomes with definite biological implication for almost all eukaryotic species. In this work, we investigated, for the first time, the differential proteomic profile of Saccharomyces cerevisiae culture arrested at mitotic metaphase (M) and metaphase-I (MI) of meiosis using 2-DE and 2D-DIGE. Our findings of up-regulation of actin and its negative regulator cofilin during meiosis suggest that the rate of actin cytoskeleton turnover is more in meiosis and actin cytoskeleton may play more crucial role during meiosis compared to mitosis. Present study also suggests that actin

Distinct chromatin environment associated with phosphorylated H3S10 histone during pollen mitosis I in orchids.

Science.gov (United States)

Sharma, Santosh Kumar; Yamamoto, Maki; Mukai, Yasuhiko

2017-01-01

Pollen developmental pathway in plants involving synchronized transferal of cellular divisions from meiosis (microsporogenesis) to mitosis (pollen mitosis I/II) eventually offers a unique "meiosis-mitosis shift" at pollen mitosis I. Since the cell type (haploid microspore) and fate of pollen mitosis I differ from typical mitosis (in meristem cells), it is immensely important to analyze the chromosomal distribution of phosphorylated H3S10 histone during atypical pollen mitosis I to comprehend the role of histone phosphorylation in pollen development. We investigated the chromosomal phosphorylation of H3S10 histone during pollen mitosis I in orchids using immunostaining technique. The chromosomal distribution of H3S10ph during pollen mitosis I revealed differential pattern than that of typical mitosis in plants, however, eventually following the similar trends of mitosis in animals where H3S10 phosphorylation begins in the pericentromeric regions first, later extending to the whole chromosomes, and finally declining at anaphase/early cytokinesis (differentiation of vegetative and generative cells). The study suggests that the chromosomal distribution of H3S10ph during cell division is not universal and can be altered between different cell types encoded for diverse cellular processes. During pollen development, phosphorylation of histone might play a critical role in chromosome condensation events throughout pollen mitosis I in plants.

Maximized Inter-Class Weighted Mean for Fast and Accurate Mitosis Cells Detection in Breast Cancer Histopathology Images.

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Nateghi, Ramin; Danyali, Habibollah; Helfroush, Mohammad Sadegh

2017-08-14

Based on the Nottingham criteria, the number of mitosis cells in histopathological slides is an important factor in diagnosis and grading of breast cancer. For manual grading of mitosis cells, histopathology slides of the tissue are examined by pathologists at 40× magnification for each patient. This task is very difficult and time-consuming even for experts. In this paper, a fully automated method is presented for accurate detection of mitosis cells in histopathology slide images. First a method based on maximum-likelihood is employed for segmentation and extraction of mitosis cell. Then a novel Maximized Inter-class Weighted Mean (MIWM) method is proposed that aims at reducing the number of extracted non-mitosis candidates that results in reducing the false positive mitosis detection rate. Finally, segmented candidates are classified into mitosis and non-mitosis classes by using a support vector machine (SVM) classifier. Experimental results demonstrate a significant improvement in accuracy of mitosis cells detection in different grades of breast cancer histopathological images.

Copper-Catalyzed Domino Three-Component Approach for the Assembly of 2-Aminated Benzimidazoles and Quinazolines.

Science.gov (United States)

Tran, Lam Quang; Li, Jihui; Neuville, Luc

2015-06-19

A copper-promoted three-component synthesis of 2-aminobenzimidazoles (1) or of 2-aminoquinazolines (2) involving cyanamides, arylboronic acids, and amines has been developed. The operationally simple oxidative process, performed in the presence of K2CO3, a catalytic amount of CuCl2·2H2O, 2,2'-bipyridine, and an O2 atmosphere (1 atm), allows the rapid assembly of either benzimidazoles or quinazolines starting from aryl- or benzyl-substituted cyanamides, respectively. In this process, the copper promotes the formation of three bonds, two C-N bonds, and an additional bond resulting from C-H functionalization event.

EWSR1 regulates mitosis by dynamically influencing microtubule acetylation.

Science.gov (United States)

Wang, Yi-Long; Chen, Hui; Zhan, Yi-Qun; Yin, Rong-Hua; Li, Chang-Yan; Ge, Chang-Hui; Yu, Miao; Yang, Xiao-Ming

2016-08-17

EWSR1, participating in transcription and splicing, has been identified as a translocation partner for various transcription factors, resulting in translocation, which in turn plays crucial roles in tumorigenesis. Recent studies have investigated the role of EWSR1 in mitosis. However, the effect of EWSR1 on mitosis is poorly understood. Here, we observed that depletion of EWSR1 resulted in cell cycle arrest in the mitotic phase, mainly due to an increase in the time from nuclear envelope breakdown to metaphase, resulting in a high percentage of unaligned chromosomes and multipolar spindles. We also demonstrated that EWSR1 is a spindle-associated protein that interacts with α-tubulin during mitosis. EWSR1 depletion increased the cold-sensitivity of spindle microtubules, and decreased the rate of spindle assembly. EWSR1 regulated the level of microtubule acetylation in the mitotic spindle; microtubule acetylation was rescued in EWSR1-depleted mitotic cells following suppression of HDAC6 activity by its specific inhibitor or siRNA treatment. In summary, these results suggest that EWSR1 regulates the acetylation of microtubules in a cell cycle-dependent manner through its dynamic location on spindle MTs, and may be a novel regulator for mitosis progress independent of its translocation.

Resumption of mitosis in frozen-thawed embryos is not related to the chromosomal constitution

DEFF Research Database (Denmark)

Agerholm, Inge E; Kølvrå, Steen; Crüger, Dorthe G

2007-01-01

OBJECTIVE: To study the relation between the resumption of mitosis after thaw and chromosomal constitution in frozen-thawed embryos. In addition, to evaluate the correlation among the three parameters of resumption of mitosis after thaw, postthaw blastomere loss, and multinucleation. DESIGN: Frozen......(S): Forty IVF and/or intracytoplasmic sperm injection patients. INTERVENTION(S): Embryo thawing, morphological evaluation, and fluorescence in situ hybridization analysis for aneuploidy screening. MAIN OUTCOME MEASURE(S): Resumption of mitosis, blastomere loss, multinucleation, and chromosome enumeration....... RESULT(S): No difference was observed in the chromosomal constitution of embryos with and without resumption of mitosis. Neither was the postthaw blastomere loss connected to the chromosomal constitution. The resumption of mitosis was not associated with postthaw loss of blastomeres...

Phosphorylation of AIB1 at Mitosis Is Regulated by CDK1/CYCLIN B

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Ferrero, Macarena; Ferragud, Juan; Orlando, Leonardo; Valero, Luz; Sánchez del Pino, Manuel; Farràs, Rosa; Font de Mora, Jaime

2011-01-01

Background Although the AIB1 oncogene has an important role during the early phase of the cell cycle as a coactivator of E2F1, little is known about its function during mitosis. Methodology/Principal Findings Mitotic cells isolated by nocodazole treatment as well as by shake-off revealed a post-translational modification occurring in AIB1 specifically during mitosis. This modification was sensitive to the treatment with phosphatase, suggesting its modification by phosphorylation. Using specific inhibitors and in vitro kinase assays we demonstrate that AIB1 is phosphorylated on Ser728 and Ser867 by Cdk1/cyclin B at the onset of mitosis and remains phosphorylated until exit from M phase. Differences in the sensitivity to phosphatase inhibitors suggest that PP1 mediates dephosphorylation of AIB1 at the end of mitosis. The phosphorylation of AIB1 during mitosis was not associated with ubiquitylation or degradation, as confirmed by western blotting and flow cytometry analysis. In addition, luciferase reporter assays showed that this phosphorylation did not alter the transcriptional properties of AIB1. Importantly, fluorescence microscopy and sub-cellular fractionation showed that AIB1 phosphorylation correlated with the exclusion from the condensed chromatin, thus preventing access to the promoters of AIB1-dependent genes. Phospho-specific antibodies developed against Ser728 further demonstrated the presence of phosphorylated AIB1 only in mitotic cells where it was localized preferentially in the periphery of the cell. Conclusions Collectively, our results describe a new mechanism for the regulation of AIB1 during mitosis, whereby phosphorylation of AIB1 by Cdk1 correlates with the subcellular redistribution of AIB1 from a chromatin-associated state in interphase to a more peripheral localization during mitosis. At the exit of mitosis, AIB1 is dephosphorylated, presumably by PP1. This exclusion from chromatin during mitosis may represent a mechanism for governing the

Raptor is phosphorylated by cdc2 during mitosis.

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Dana M Gwinn

2010-02-01

Full Text Available The appropriate control of mitotic entry and exit is reliant on a series of interlocking signaling events that coordinately drive the biological processes required for accurate cell division. Overlaid onto these signals that promote orchestrated cell division are checkpoints that ensure appropriate mitotic spindle formation, a lack of DNA damage, kinetochore attachment, and that each daughter cell has the appropriate complement of DNA. We recently discovered that AMP-activated protein kinase (AMPK modulates the G2/M phase of cell cycle progression in part through its suppression of mammalian target of rapamycin (mTOR signaling. AMPK directly phosphorylates the critical mTOR binding partner raptor inhibiting mTORC1 (mTOR-raptor rapamycin sensitive mTOR kinase complex 1. As mTOR has been previously tied to mitotic control, we examined further how raptor may contribute to this process.We have discovered that raptor becomes highly phosphorylated in cells in mitosis. Utilizing tandem mass spectrometry, we identified a number of novel phosphorylation sites in raptor, and using phospho-specific antibodies demonstrated that raptor becomes phosphorylated on phospho-serine/threonine-proline sites in mitosis. A combination of site-directed mutagenesis in a tagged raptor cDNA and analysis with a series of new phospho-specific antibodies generated against different sites in raptor revealed that Serine 696 and Threonine 706 represent two key sites in raptor phosphorylated in mitosis. We demonstrate that the mitotic cyclin-dependent kinase cdc2/CDK1 is the kinase responsible for phosphorylating these sites, and its mitotic partner Cyclin B efficiently coimmunoprecipitates with raptor in mitotic cells.This study demonstrates that the key mTOR binding partner raptor is directly phosphorylated during mitosis by cdc2. This reinforces previous studies suggesting that mTOR activity is highly regulated and important for mitotic progression, and points to a direct

Apoptosis and mitosis as prognostic factors in pathologically staged N1 nonsmall cell lung cancer

International Nuclear Information System (INIS)

Komaki, Ritsuko; Fujii, Takashi; Perkins, Penny; Ro, Jae Y.; Allen, Pamela K.; Mason, Kathryn A.; Mountain, Clifton F.; Milas, Luka

1996-01-01

Purpose: This study aimed to establish whether spontaneous apoptosis or mitosis has prognostic value among patients with pathologically staged N1 nonsmall cell lung carcinoma (NSCLC) treated with surgical resection with or without adjuvant therapy. Methods and Materials: Material from 173 patients who had resections between 1970 and 1988 was analyzed for apoptosis and mitosis. There were 128 men and 45 women, with a median age of 61 years. There were 86 squamous cell carcinomas (SQ), 73 adenocarcinomas (AC), 3 large-cell carcinomas (LC), 6 SQ-AC, and 5 unclassified. Patients were observed from 2 to 209 months (median 27). Actuarial methods were used to assess survival and freedom from distant metastasis. Results: In NSCLC, apoptosis was found to range from 0.2% to 2.8% (median 1.0%) and mitosis from 0 to 1.8% (median 0.4%). Tumors having higher levels of apoptosis also had higher levels of mitosis (p = 0.001). The values of neither apoptosis nor mitosis depended on size, location, differentiation of tumors, age, performance status, or weight loss of patients. However, the values of apoptosis depended on tumor histology in that high values (greater than or equal to the median) were more frequent in SQ (49%) than in AC/LC (29%) (p 0.01). The overall survival for NSCLC patients, which was 33% at 5 years, did not depend on the level of either apoptosis or mitosis. The 5-year survival of patients having SQ was higher (43%) than that of patients having AC/LC (21%) (p = 0.03). Patients with high apoptosis showed significantly better 5-year overall (p = 0.008) and DMF (p = 0.0012) survivals in the SQ group compared to the AC/LC group. High mitosis compared to low mitosis was a significantly better predictor for 5-year survival (62% vs. 29%, respectively) (p = 0.035) in the SQ. However, high mitosis was a significantly worse 5-year DMF survival predictor compared to low mitosis: 13% vs. 56%, respectively (p = 0.05) in AC/LC. In the multivariate models for AC/LC, mitosis

Monitoring the elasticity changes of HeLa cells during mitosis by atomic force microscopy

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Jiang, Ningcheng; Wang, Yuhua; Zeng, Jinshu; Ding, Xuemei; Xie, Shusen; Yang, Hongqin

2016-10-01

Cell mitosis plays a crucial role in cell life activity, which is one of the important phases in cell division cycle. During the mitosis, the cytoskeleton micro-structure of the cell changed and the biomechanical properties of the cell may vary depending upon different mitosis stages. In this study, the elasticity property of HeLa cells during mitosis was monitored by atomic force microscopy. Also, the actin filaments in different mitosis stages of the cells were observed by confocal imaging. Our results show that the cell in anaphase is stiffer than that in metaphase and telophase. Furthermore, lots of actin filaments gathered in cells' center area in anaphase, which contributes to the rigidity of the cell in this phase. Our findings demonstrate that the nano-biomechanics of living cells could provide a new index for characterizing cell physiological states.

Centriole distribution during tripolar mitosis in Chinese hamster ovary cells

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1984-01-01

During bipolar mitosis a pair of centrioles is distributed to each cell but the activities of the two centrioles within the pair are not equivalent. The parent is normally surrounded by a cloud of pericentriolar material that serves as a microtubule-organizing center. The daughter does not become associated with pericentriolar material until it becomes a parent in the next cell cycle (Rieder, C.L., and G. G. Borisy , 1982, Biol. Cell., 44:117-132). We asked whether the microtubule-organizing activity associated with a centriole was dependent on its becoming a parent. We induced multipolar mitosis in Chinese hamster ovary cells by treatment with 0.04 micrograms/ml colcemid for 4 h. After recovery from this colcemid block, the majority of cells divided into two, but 40% divided into three and 2% divided into four. The tripolar mitotic cells were examined by antitubulin immunofluorescence and by high voltage electron microscopy of serial thick (0.25-micron) sections. The electron microscope analysis showed that centriole number was conserved and that the centrioles were distributed among the three spindle poles, generally in a 2:1:1 or 2:2:0 pattern. The first pattern shows that centriole parenting is not prerequisite for association with pole function; the second pattern indicates that centrioles per se are not required at all. However, the frequency of midbody formation and successful division was higher when centrioles were present in the 2:1:1 pattern. We suggest that the centrioles may help the proper distribution and organization of the pericentriolar cloud, which is needed for the formation of a functional spindle pole. PMID:6373793

Synthesis, molecular docking, DFT calculations and cytotoxicity activity of benzo[g]quinazoline derivatives in choline chloride-urea

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Lakshmanan, Sivalingam; Govindaraj, Dharman; Ramalakshmi, Narayanan; Antony, S. Arul

2017-12-01

Green and highly efficient one-pot three component approach for the synthesis of benzo[g]quinazoline derivatives (6a-g) using Choline chloride-urea (DES). Synthesized compounds 6b and 6g showed the most potent biological activity against A549 lung cancer cell line. Docking simulation was performed to position compounds 6b and 6g showed the greater affinity for anaplastic lymphoma kinase (ALK) receptor. Quantum chemical studies were carried out on these compounds to understand the structural features essential for activity using DFT/6-31G level of theory.

Pathologic mitoses and pathology of mitosis in tumorigenesis

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RG Steinbeck

2009-12-01

Full Text Available The gist of my hypothesis (.. is a certain abnormal chromatin constitution. Each process, which brings about this chromatin constitution, would result in the origin of a malignant tumour. Certainly, I consider irregularities with mitosis as the normal mode of the origin of an incorrectly assembled nucleus. This statement by Boveri (1914 has considered earlier observations of asymmetric divisions in human cancers (Hansemann, 1890. The hypothesis is based on the understanding of mitosis as an equational bipartition of the hereditary substance (Flemming, 1879; Roux, 1883. Latest since it was known that genes are located on chromosomes (Sturtevant, 1913, their balanced transport in anaphase appeared as a condition of correct somatic proliferation. True mitoses guarantee the constancy of terminally differentiated tissues. Politzer (1934 has performed X-ray experiments to investigate abnormal karyokinesis with regard to anomalous chromatin condensation, chromosome breakage, spindle malformation, and failure in cytokinesis. On the basis of light microscopy, further significant progress in understanding the pathology of mitosis was not possible. Tumour cases with reduced chromosome numbers seduced to the idea that mitotic activity is rather under cytoplasmic than under nuclear control (Koller, 1947.

p53 Dependent Centrosome Clustering Prevents Multipolar Mitosis in Tetraploid Cells

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Yi, Qiyi; Zhao, Xiaoyu; Huang, Yun; Ma, Tieliang; Zhang, Yingyin; Hou, Heli; Cooke, Howard J.; Yang, Da-Qing; Wu, Mian; Shi, Qinghua

2011-01-01

Background p53 abnormality and aneuploidy often coexist in human tumors, and tetraploidy is considered as an intermediate between normal diploidy and aneuploidy. The purpose of this study was to investigate whether and how p53 influences the transformation from tetraploidy to aneuploidy. Principal Findings Live cell imaging was performed to determine the fates and mitotic behaviors of several human and mouse tetraploid cells with different p53 status, and centrosome and spindle immunostaining was used to investigate centrosome behaviors. We found that p53 dominant-negative mutation, point mutation, or knockout led to a 2∼ 33-fold increase of multipolar mitosis in N/TERT1, 3T3 and mouse embryonic fibroblasts (MEFs), while mitotic entry and cell death were not significantly affected. In p53-/- tetraploid MEFs, the ability of centrosome clustering was compromised, while centrosome inactivation was not affected. Suppression of RhoA/ROCK activity by specific inhibitors in p53-/- tetraploid MEFs enhanced centrosome clustering, decreased multipolar mitosis from 38% to 20% and 16% for RhoA and ROCK, respectively, while expression of constitutively active RhoA in p53+/+ tetraploid 3T3 cells increased the frequency of multipolar mitosis from 15% to 35%. Conclusions p53 could not prevent tetraploid cells entering mitosis or induce tetraploid cell death. However, p53 abnormality impaired centrosome clustering and lead to multipolar mitosis in tetraploid cells by modulating the RhoA/ROCK signaling pathway. PMID:22076149

Mitosis Counting in Breast Cancer: Object-Level Interobserver Agreement and Comparison to an Automatic Method.

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Veta, Mitko; van Diest, Paul J; Jiwa, Mehdi; Al-Janabi, Shaimaa; Pluim, Josien P W

2016-01-01

Tumor proliferation speed, most commonly assessed by counting of mitotic figures in histological slide preparations, is an important biomarker for breast cancer. Although mitosis counting is routinely performed by pathologists, it is a tedious and subjective task with poor reproducibility, particularly among non-experts. Inter- and intraobserver reproducibility of mitosis counting can be improved when a strict protocol is defined and followed. Previous studies have examined only the agreement in terms of the mitotic count or the mitotic activity score. Studies of the observer agreement at the level of individual objects, which can provide more insight into the procedure, have not been performed thus far. The development of automatic mitosis detection methods has received large interest in recent years. Automatic image analysis is viewed as a solution for the problem of subjectivity of mitosis counting by pathologists. In this paper we describe the results from an interobserver agreement study between three human observers and an automatic method, and make two unique contributions. For the first time, we present an analysis of the object-level interobserver agreement on mitosis counting. Furthermore, we train an automatic mitosis detection method that is robust with respect to staining appearance variability and compare it with the performance of expert observers on an "external" dataset, i.e. on histopathology images that originate from pathology labs other than the pathology lab that provided the training data for the automatic method. The object-level interobserver study revealed that pathologists often do not agree on individual objects, even if this is not reflected in the mitotic count. The disagreement is larger for objects from smaller size, which suggests that adding a size constraint in the mitosis counting protocol can improve reproducibility. The automatic mitosis detection method can perform mitosis counting in an unbiased way, with substantial

Testing of mitosis and meiosis in female and male gametes

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L. F. Kurilo

2016-01-01

Full Text Available Method of quantitative evaluation of the immature germ cells, their pathology in mitosis and meiosis (in semen, embryo and fetal ovaries, of gonad biopsies or fragments of sectioned material is informative method and should be introduced into the clinical practice in andrology and gynecology and fundamental research. Quantitative analysis of mitosis and female meiosis development was initiated on experimental animals and fetal gonads from spontaneous or therapeutic abortions.

Phosphorylation of CPAP by Aurora-A Maintains Spindle Pole Integrity during Mitosis

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En-Ju Chou

2016-03-01

Full Text Available CPAP is required for centriole elongation during S/G2 phase, but the role of CPAP in mitosis is incompletely understood. Here, we show that CPAP maintains spindle pole integrity through its phosphorylation by Aurora-A during mitosis. Depletion of CPAP induced a prolonged delay in mitosis, pericentriolar material (PCM dispersion, and multiple mitotic abnormalities. Further studies demonstrated that CPAP directly interacts with and is phosphorylated by Aurora-A at serine 467 during mitosis. Interestingly, the dispersal of the PCM was effectively rescued by ectopic expression of wild-type CPAP or a phospho-mimic CPAP-S467D mutant, but not a non-phosphorylated CPAP-S467A mutant. Finally, we found that CPAP-S467D has a low affinity for microtubule binding but a high affinity for PCM proteins. Together, our results support a model wherein CPAP is required for proper mitotic progression, and phosphorylation of CPAP by Aurora-A is essential for maintaining spindle pole integrity.

A nutrient dependant switch explains mutually exclusive existence of meiosis and mitosis initiation in budding yeast.

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Wannige, C T; Kulasiri, D; Samarasinghe, S

2014-01-21

Nutrients from living environment are vital for the survival and growth of any organism. Budding yeast diploid cells decide to grow by mitosis type cell division or decide to create unique, stress resistant spores by meiosis type cell division depending on the available nutrient conditions. To gain a molecular systems level understanding of the nutrient dependant switching between meiosis and mitosis initiation in diploid cells of budding yeast, we develop a theoretical model based on ordinary differential equations (ODEs) including the mitosis initiator and its relations to budding yeast meiosis initiation network. Our model accurately and qualitatively predicts the experimentally revealed temporal variations of related proteins under different nutrient conditions as well as the diverse mutant studies related to meiosis and mitosis initiation. Using this model, we show how the meiosis and mitosis initiators form an all-or-none type bistable switch in response to available nutrient level (mainly nitrogen). The transitions to and from meiosis or mitosis initiation states occur via saddle node bifurcation. This bidirectional switch helps the optimal usage of available nutrients and explains the mutually exclusive existence of meiosis and mitosis pathways. © 2013 Elsevier Ltd. All rights reserved.

Quantitative comparison of a human cancer cell surface proteome between interphase and mitosis.

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Özlü, Nurhan; Qureshi, Mohammad H; Toyoda, Yusuke; Renard, Bernhard Y; Mollaoglu, Gürkan; Özkan, Nazlı E; Bulbul, Selda; Poser, Ina; Timm, Wiebke; Hyman, Anthony A; Mitchison, Timothy J; Steen, Judith A

2015-01-13

The cell surface is the cellular compartment responsible for communication with the environment. The interior of mammalian cells undergoes dramatic reorganization when cells enter mitosis. These changes are triggered by activation of the CDK1 kinase and have been studied extensively. In contrast, very little is known of the cell surface changes during cell division. We undertook a quantitative proteomic comparison of cell surface-exposed proteins in human cancer cells that were tightly synchronized in mitosis or interphase. Six hundred and twenty-eight surface and surface-associated proteins in HeLa cells were identified; of these, 27 were significantly enriched at the cell surface in mitosis and 37 in interphase. Using imaging techniques, we confirmed the mitosis-selective cell surface localization of protocadherin PCDH7, a member of a family with anti-adhesive roles in embryos. We show that PCDH7 is required for development of full mitotic rounding pressure at the onset of mitosis. Our analysis provided basic information on how cell cycle progression affects the cell surface. It also provides potential pharmacodynamic biomarkers for anti-mitotic cancer chemotherapy. © 2014 The Authors.

How protein kinases co-ordinate mitosis in animal cells.

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Ma, Hoi Tang; Poon, Randy Y C

2011-04-01

Mitosis is associated with profound changes in cell physiology and a spectacular surge in protein phosphorylation. To accomplish these, a remarkably large portion of the kinome is involved in the process. In the present review, we will focus on classic mitotic kinases, such as cyclin-dependent kinases, Polo-like kinases and Aurora kinases, as well as more recently characterized players such as NIMA (never in mitosis in Aspergillus nidulans)-related kinases, Greatwall and Haspin. Together, these kinases co-ordinate the proper timing and fidelity of processes including centrosomal functions, spindle assembly and microtubule-kinetochore attachment, as well as sister chromatid separation and cytokinesis. A recurrent theme of the mitotic kinase network is the prevalence of elaborated feedback loops that ensure bistable conditions. Sequential phosphorylation and priming phosphorylation on substrates are also frequently employed. Another important concept is the role of scaffolds, such as centrosomes for protein kinases during mitosis. Elucidating the entire repertoire of mitotic kinases, their functions, regulation and interactions is critical for our understanding of normal cell growth and in diseases such as cancers.

Mathematical imaging methods for mitosis analysis in live-cell phase contrast microscopy.

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Grah, Joana Sarah; Harrington, Jennifer Alison; Koh, Siang Boon; Pike, Jeremy Andrew; Schreiner, Alexander; Burger, Martin; Schönlieb, Carola-Bibiane; Reichelt, Stefanie

2017-02-15

In this paper we propose a workflow to detect and track mitotic cells in time-lapse microscopy image sequences. In order to avoid the requirement for cell lines expressing fluorescent markers and the associated phototoxicity, phase contrast microscopy is often preferred over fluorescence microscopy in live-cell imaging. However, common specific image characteristics complicate image processing and impede use of standard methods. Nevertheless, automated analysis is desirable due to manual analysis being subjective, biased and extremely time-consuming for large data sets. Here, we present the following workflow based on mathematical imaging methods. In the first step, mitosis detection is performed by means of the circular Hough transform. The obtained circular contour subsequently serves as an initialisation for the tracking algorithm based on variational methods. It is sub-divided into two parts: in order to determine the beginning of the whole mitosis cycle, a backwards tracking procedure is performed. After that, the cell is tracked forwards in time until the end of mitosis. As a result, the average of mitosis duration and ratios of different cell fates (cell death, no division, division into two or more daughter cells) can be measured and statistics on cell morphologies can be obtained. All of the tools are featured in the user-friendly MATLAB®Graphical User Interface MitosisAnalyser. Copyright © 2017. Published by Elsevier Inc.

Tripolar mitosis in human cells and embryos: occurrence, pathophysiology and medical implications.

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Kalatova, Beata; Jesenska, Renata; Hlinka, Daniel; Dudas, Marek

2015-01-01

Tripolar mitosis is a specific case of cell division driven by typical molecular mechanisms of mitosis, but resulting in three daughter cells instead of the usual count of two. Other variants of multipolar mitosis show even more mitotic poles and are relatively rare. In nature, this phenomenon was frequently observed or suspected in multiple common cancers, infected cells, the placenta, and in early human embryos with impaired pregnancy-yielding potential. Artificial causes include radiation and various toxins. Here we combine several pieces of the most recent evidence for the existence of different types of multipolar mitosis in preimplantation embryos together with a detailed review of the literature. The related molecular and cellular mechanisms are discussed, including the regulation of centriole duplication, mitotic spindle biology, centromere functions, cell cycle checkpoints, mitotic autocorrection mechanisms, and the related complicating factors in healthy and affected cells, including post-mitotic cell-cell fusion often associated with multipolar cell division. Clinical relevance for oncology and embryo selection in assisted reproduction is also briefly discussed in this context. Copyright © 2014 Elsevier GmbH. All rights reserved.

Phosphorylation of CPAP by Aurora-A Maintains Spindle Pole Integrity during Mitosis.

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Chou, En-Ju; Hung, Liang-Yi; Tang, Chieh-Ju C; Hsu, Wen-Bin; Wu, Hsin-Yi; Liao, Pao-Chi; Tang, Tang K

2016-03-29

CPAP is required for centriole elongation during S/G2 phase, but the role of CPAP in mitosis is incompletely understood. Here, we show that CPAP maintains spindle pole integrity through its phosphorylation by Aurora-A during mitosis. Depletion of CPAP induced a prolonged delay in mitosis, pericentriolar material (PCM) dispersion, and multiple mitotic abnormalities. Further studies demonstrated that CPAP directly interacts with and is phosphorylated by Aurora-A at serine 467 during mitosis. Interestingly, the dispersal of the PCM was effectively rescued by ectopic expression of wild-type CPAP or a phospho-mimic CPAP-S467D mutant, but not a non-phosphorylated CPAP-S467A mutant. Finally, we found that CPAP-S467D has a low affinity for microtubule binding but a high affinity for PCM proteins. Together, our results support a model wherein CPAP is required for proper mitotic progression, and phosphorylation of CPAP by Aurora-A is essential for maintaining spindle pole integrity. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Characterization of mitosis-specific phosphorylation of tumor-associated microtubule-associated protein

OpenAIRE

Hong, Kyung Uk; Kim, Hyun-Jun; Bae, Chang-Dae; Park, Joobae

2009-01-01

Tumor-associated microtubule-associated protein (TMAP), also known as cytoskeleton associated protein 2 (CKAP2), has been recently shown to be involved in the assembly and maintenance of mitotic spindle and also plays an essential role in maintaining the fidelity of chromosome segregation during mitosis. We have previously reported that TMAP is phosphorylated at multiple residues specifically during mitosis, and characterized the mechanism and functional importance of phosphorylation at one o...

EGF stimulates the activation of EGF receptors and the selective activation of major signaling pathways during mitosis.

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Wee, Ping; Shi, Huaiping; Jiang, Jennifer; Wang, Yuluan; Wang, Zhixiang

2015-03-01

Mitosis and epidermal growth factor (EGF) receptor (EGFR) are both targets for cancer therapy. The role of EGFR signaling in mitosis has been rarely studied and poorly understood. The limited studies indicate that the activation of EGFR and downstream signaling pathways is mostly inhibited during mitosis. However, we recently showed that EGFR is phosphorylated in response to EGF stimulation in mitosis. Here we studied EGF-induced EGFR activation and the activation of major signaling pathways downstream of EGFR during mitosis. We showed that EGFR was strongly activated by EGF during mitosis as all the five major tyrosine residues including Y992, Y1045, Y1068, Y1086, and Y1173 were phosphorylated to a level similar to that in the interphase. We further showed that the activated EGFR is able to selectively activate some downstream signaling pathways while avoiding others. Activated EGFR is able to activate PI3K and AKT2, but not AKT1, which may be responsible for the observed effects of EGF against nocodazole-induced cell death. Activated EGFR is also able to activate c-Src, c-Cbl and PLC-γ1 during mitosis. However, activated EGFR is unable to activate ERK1/2 and their downstream substrates RSK and Elk-1. While it activated Ras, EGFR failed to fully activate Raf-1 in mitosis due to the lack of phosphorylation at Y341 and the lack of dephosphorylation at pS259. We conclude that contrary to the dogma, EGFR is activated by EGF during mitosis. Moreover, EGFR-mediated cell signaling is regulated differently from the interphase to specifically serve the needs of the cell in mitosis. Copyright © 2015 Elsevier Inc. All rights reserved.

The duration of mitosis and daughter cell size are modulated by nutrients in budding yeast.

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Leitao, Ricardo M; Kellogg, Douglas R

2017-11-06

The size of nearly all cells is modulated by nutrients. Thus, cells growing in poor nutrients can be nearly half the size of cells in rich nutrients. In budding yeast, cell size is thought to be controlled almost entirely by a mechanism that delays cell cycle entry until sufficient growth has occurred in G1 phase. Here, we show that most growth of a new daughter cell occurs in mitosis. When the rate of growth is slowed by poor nutrients, the duration of mitosis is increased, which suggests that cells compensate for slow growth in mitosis by increasing the duration of growth. The amount of growth required to complete mitosis is reduced in poor nutrients, leading to a large reduction in cell size. Together, these observations suggest that mechanisms that control the extent of growth in mitosis play a major role in cell size control in budding yeast. © 2017 Leitao and Kellogg.

A mitosis-specific and R loop-driven ATR pathway promotes faithful chromosome segregation.

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Kabeche, Lilian; Nguyen, Hai Dang; Buisson, Rémi; Zou, Lee

2018-01-05

The ataxia telangiectasia mutated and Rad3-related (ATR) kinase is crucial for DNA damage and replication stress responses. Here, we describe an unexpected role of ATR in mitosis. Acute inhibition or degradation of ATR in mitosis induces whole-chromosome missegregation. The effect of ATR ablation is not due to altered cyclin-dependent kinase 1 (CDK1) activity, DNA damage responses, or unscheduled DNA synthesis but to loss of an ATR function at centromeres. In mitosis, ATR localizes to centromeres through Aurora A-regulated association with centromere protein F (CENP-F), allowing ATR to engage replication protein A (RPA)-coated centromeric R loops. As ATR is activated at centromeres, it stimulates Aurora B through Chk1, preventing formation of lagging chromosomes. Thus, a mitosis-specific and R loop-driven ATR pathway acts at centromeres to promote faithful chromosome segregation, revealing functions of R loops and ATR in suppressing chromosome instability. Copyright © 2018, American Association for the Advancement of Science.

How unfinished business from S-phase affects mitosis and beyond

DEFF Research Database (Denmark)

Mankouri, H.W.; Huttner, D.; Hickson, I.D.

2013-01-01

The eukaryotic cell cycle is conventionally viewed as comprising several discrete steps, each of which must be completed before the next one is initiated. However, emerging evidence suggests that incompletely replicated, or unresolved, chromosomes from S-phase can persist into mitosis, where...... they present a potential threat to the faithful segregation of sister chromatids. In this review, we provide an overview of the different classes of loci where this 'unfinished S-phase business' can lead to a variety of cytogenetically distinct DNA structures throughout the various steps of mitosis...

CSL protein regulates transcription of genes required to prevent catastrophic mitosis in fission yeast.

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Převorovský, Martin; Oravcová, Martina; Zach, Róbert; Jordáková, Anna; Bähler, Jürg; Půta, František; Folk, Petr

2016-11-16

For every eukaryotic cell to grow and divide, intricately coordinated action of numerous proteins is required to ensure proper cell-cycle progression. The fission yeast Schizosaccharomyces pombe has been instrumental in elucidating the fundamental principles of cell-cycle control. Mutations in S. pombe 'cut' (cell untimely torn) genes cause failed coordination between cell and nuclear division, resulting in catastrophic mitosis. Deletion of cbf11, a fission yeast CSL transcription factor gene, triggers a 'cut' phenotype, but the precise role of Cbf11 in promoting mitotic fidelity is not known. We report that Cbf11 directly activates the transcription of the acetyl-coenzyme A carboxylase gene cut6, and the biotin uptake/biosynthesis genes vht1 and bio2, with the former 2 implicated in mitotic fidelity. Cbf11 binds to a canonical, metazoan-like CSL response element (GTGGGAA) in the cut6 promoter. Expression of Cbf11 target genes shows apparent oscillations during the cell cycle using temperature-sensitive cdc25-22 and cdc10-M17 block-release experiments, but not with other synchronization methods. The penetrance of catastrophic mitosis in cbf11 and cut6 mutants is nutrient-dependent. We also show that drastic decrease in biotin availability arrests cell proliferation but does not cause mitotic defects. Taken together, our results raise the possibility that CSL proteins play conserved roles in regulating cell-cycle progression, and they could guide experiments into mitotic CSL functions in mammals.

Translocation of the papillomavirus L2/vDNA complex across the limiting membrane requires the onset of mitosis.

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Calton, Christine M; Bronnimann, Matthew P; Manson, Ariana R; Li, Shuaizhi; Chapman, Janice A; Suarez-Berumen, Marcela; Williamson, Tatum R; Molugu, Sudheer K; Bernal, Ricardo A; Campos, Samuel K

2017-05-01

The human papillomavirus type 16 (HPV16) L2 protein acts as a chaperone to ensure that the viral genome (vDNA) traffics from endosomes to the trans-Golgi network (TGN) and eventually the nucleus, where HPV replication occurs. En route to the nucleus, the L2/vDNA complex must translocate across limiting intracellular membranes. The details of this critical process remain poorly characterized. We have developed a system based on subcellular compartmentalization of the enzyme BirA and its cognate substrate to detect membrane translocation of L2-BirA from incoming virions. We find that L2 translocation requires transport to the TGN and is strictly dependent on entry into mitosis, coinciding with mitotic entry in synchronized cells. Cell cycle arrest causes retention of L2/vDNA at the TGN; only release and progression past G2/M enables translocation across the limiting membrane and subsequent infection. Microscopy of EdU-labeled vDNA reveals a rapid and dramatic shift in vDNA localization during early mitosis. At late G2/early prophase vDNA egresses from the TGN to a pericentriolar location, accumulating there through prometaphase where it begins to associate with condensed chromosomes. By metaphase and throughout anaphase the vDNA is seen bound to the mitotic chromosomes, ensuring distribution into both daughter nuclei. Mutations in a newly defined chromatin binding region of L2 potently blocked translocation, suggesting that translocation is dependent on chromatin binding during prometaphase. This represents the first time a virus has been shown to functionally couple the penetration of limiting membranes to cellular mitosis, explaining in part the tropism of HPV for mitotic basal keratinocytes.

Abnormal mitosis triggers p53-dependent cell cycle arrest in human tetraploid cells.

Science.gov (United States)

Kuffer, Christian; Kuznetsova, Anastasia Yurievna; Storchová, Zuzana

2013-08-01

Erroneously arising tetraploid mammalian cells are chromosomally instable and may facilitate cell transformation. An increasing body of evidence shows that the propagation of mammalian tetraploid cells is limited by a p53-dependent arrest. The trigger of this arrest has not been identified so far. Here we show by live cell imaging of tetraploid cells generated by an induced cytokinesis failure that most tetraploids arrest and die in a p53-dependent manner after the first tetraploid mitosis. Furthermore, we found that the main trigger is a mitotic defect, in particular, chromosome missegregation during bipolar mitosis or spindle multipolarity. Both a transient multipolar spindle followed by efficient clustering in anaphase as well as a multipolar spindle followed by multipolar mitosis inhibited subsequent proliferation to a similar degree. We found that the tetraploid cells did not accumulate double-strand breaks that could cause the cell cycle arrest after tetraploid mitosis. In contrast, tetraploid cells showed increased levels of oxidative DNA damage coinciding with the p53 activation. To further elucidate the pathways involved in the proliferation control of tetraploid cells, we knocked down specific kinases that had been previously linked to the cell cycle arrest and p53 phosphorylation. Our results suggest that the checkpoint kinase ATM phosphorylates p53 in tetraploid cells after abnormal mitosis and thus contributes to proliferation control of human aberrantly arising tetraploids.

Phosphorylation of DEPDC1 at Ser110 is required to maintain centrosome organization during mitosis.

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Chen, Dan; Ito, Satoko; Hyodo, Toshinori; Asano-Inami, Eri; Yuan, Hong; Senga, Takeshi

2017-09-15

DEPDC1 (DEP domain containing 1) is overexpressed in multiple cancers and is associated with cell cycle progression. In this report, we have investigated the expression, localization, phosphorylation and function of DEPDC1 during mitosis. DEPDC1 has two isoforms (isoform a and isoform b), and both of them are increased in mitosis and degraded once cells exit mitosis. DEPDC1a is localized to the centrosome in metaphase, whereas DEPDC1b is localized to the entire cell cortex during mitosis. DEPDC1a, but not DEPDC1b, was required for the integrity of centrosome and organization of the bipolar spindle. Mass spectrometry and biochemical analyses revealed phosphorylation of DEPDC1 at Ser110. The phosphorylation of Ser110 is essential for localization of DEPDC1a to the centrosome. Consistently, non-phosphorylation mutants of DEPDC1a did not rescue disruption of centrosome organization by depletion of endogenous DEPDC1. Our results show a novel role for DEPDC1 in maintaining centrosome integrity during mitosis for the accurate distribution of chromosomes. Copyright © 2017. Published by Elsevier Inc.

Nonanaplastic follicular cell-derived thyroid carcinoma: mitosis and necrosis in long-term follow-up.

Science.gov (United States)

Skansing, Daniel Bräuner; Londero, Stefano Christian; Asschenfeldt, Pia; Larsen, Stine Rosenkilde; Godballe, Christian

2017-06-01

Nonanaplastic follicular cell-derived thyroid carcinoma (NAFCTC) includes differentiated- (DTC) and poorly differentiated thyroid carcinoma (PDTC). DTC has an excellent prognosis, while PDTC is situated between DTC and anaplastic carcinomas. Short-term studies suggest that PDTC patients diagnosed only on tumor necrosis and/or mitosis have a prognosis similar to those diagnosed according to the TURIN proposal. The purpose of this study was to evaluate prognosis for NAFCTC based on long-term follow-up illuminating the significance of tumor necrosis and mitosis. A cohort of 225 patients with NAFCTC was followed more than 20 years. Age, sex, distant metastasis, histology, tumor size, extrathyroidal invasion, lymph node metastasis, tumor necrosis and mitosis were examined as possible prognostic factors. Median follow-up time for patients alive was 28 years (range 20-43 years). Age, distant metastasis, extrathyroidal invasion, tumor size, tumor necrosis and mitosis were independent prognostic factors in multivariate analysis for overall survival (OS). In disease specific survival (DSS) age was not significant. Using only necrosis and/or mitosis as criteria for PDTC the 5-, 10- and 20-year OS for DTC was 87, 79 and 69%, respectively. In DSS it was 95, 92 and 90%. For PDTC the 5-, 10- and 20-year OS was 57, 40 and 25%, respectively. In DSS it was 71, 55 and 48%. Tumor necrosis and mitosis are highly significant prognostic indicators in analysis of long time survival of nonanaplastic follicular cell-derived thyroid carcinoma indicating that a simplification of the actually used criteria for poorly differentiated carcinomas may be justified.

Excess free histone H3 localizes to centrosomes for proteasome-mediated degradation during mitosis in metazoans.

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Wike, Candice L; Graves, Hillary K; Wason, Arpit; Hawkins, Reva; Gopalakrishnan, Jay; Schumacher, Jill; Tyler, Jessica K

2016-08-17

The cell tightly controls histone protein levels in order to achieve proper packaging of the genome into chromatin, while avoiding the deleterious consequences of excess free histones. Our accompanying study has shown that a histone modification that loosens the intrinsic structure of the nucleosome, phosphorylation of histone H3 on threonine 118 (H3 T118ph), exists on centromeres and chromosome arms during mitosis. Here, we show that H3 T118ph localizes to centrosomes in humans, flies, and worms during all stages of mitosis. H3 abundance at the centrosome increased upon proteasome inhibition, suggesting that excess free histone H3 localizes to centrosomes for degradation during mitosis. In agreement, we find ubiquitinated H3 specifically during mitosis and within purified centrosomes. These results suggest that targeting of histone H3 to the centrosome for proteasome-mediated degradation is a novel pathway for controlling histone supply, specifically during mitosis.

Mitotic phosphorylation of VCIP135 blocks p97ATPase-mediated Golgi membrane fusion

Energy Technology Data Exchange (ETDEWEB)

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.

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...

Mitosis, double strand break repair, and telomeres: a view from the end: how telomeres and the DNA damage response cooperate during mitosis to maintain genome stability.

Science.gov (United States)

Cesare, Anthony J

2014-11-01

Double strand break (DSB) repair is suppressed during mitosis because RNF8 and downstream DNA damage response (DDR) factors, including 53BP1, do not localize to mitotic chromatin. Discovery of the mitotic kinase-dependent mechanism that inhibits DSB repair during cell division was recently reported. It was shown that restoring mitotic DSB repair was detrimental, resulting in repair dependent genome instability and covalent telomere fusions. The telomere DDR that occurs naturally during cellular aging and in cancer is known to be refractory to G2/M checkpoint activation. Such DDR-positive telomeres, and those that occur as part of the telomere-dependent prolonged mitotic arrest checkpoint, normally pass through mitosis without covalent ligation, but result in cell growth arrest in G1 phase. The discovery that suppressing DSB repair during mitosis may function primarily to protect DDR-positive telomeres from fusing during cell division reinforces the unique cooperation between telomeres and the DDR to mediate tumor suppression. © 2014 The Author. Bioessays published by WILEY Periodicals, Inc.

Synthesis and SAR of 1-acetanilide-4-aminopyrazole-substituted quinazolines: selective inhibitors of Aurora B kinase with potent anti-tumor activity.

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Foote, Kevin M; Mortlock, Andrew A; Heron, Nicola M; Jung, Frédéric H; Hill, George B; Pasquet, Georges; Brady, Madeleine C; Green, Stephen; Heaton, Simon P; Kearney, Sarah; Keen, Nicholas J; Odedra, Rajesh; Wedge, Stephen R; Wilkinson, Robert W

2008-03-15

A new class of 1-acetanilide-4-aminopyrazole-substituted quinazoline Aurora kinase inhibitors has been discovered possessing highly potent cellular activity. Continuous infusion into athymic mice bearing SW620 tumors of the soluble phosphate derivative 2 led to dose-proportional exposure of the des-phosphate compound 8 with a high-unbound fraction. The combination of potent cell activity and high free-drug exposure led to pharmacodynamic changes in the tumor at low doses, indicative of Aurora B-kinase inhibition and a reduction in tumor volume.

Apoptosis and mitosis in the small intestine at radiation injury

International Nuclear Information System (INIS)

Hashiguchi, Junichiro; Ito, Masahiro; Onizuka, Shinya; Sekine, Ichiro; Uchida, Shinji

1990-01-01

A single whole body irradiation was given at a dose rate of 0.298 Gy/min in 6-week-old male mice. Intestinal crypt apoptosis and mitosis cells were determined by delivering radiation doses of 0.4, 0.6, 1.0, 1.5, 2.0, 5.0, 10.0, and 20.0 Gy. The incidence of apoptosis was linearly increased in a dose-dependent manner up to 5.0 Gy, and thereafter, it was gradually decreased. There was a decreased tendency for mitosis with delivering higher radiation doses. The incidence of apoptosis rapidly increased 2 hours after irradiation with either 0.6 Gy or 2.0 Gy, and reached to the peak 4 hours later. It brought about a 18-fold and 28-fold increase for 0.6 Gy and 2.0 Gy, respectively, relative to that before irradiation. Mitosis cells decreased by half one hour after irradiation with 0.6 Gy, and then returned to the pre-irradiation value through synchronization 24 hours later. The number of cells positive to BrdU was 776 in the group of mice without irradiation and 479 in the group of mice irradiated with 2.0 Gy. (N.K.)

Nuclear envelope expansion is crucial for proper chromosomal segregation during a closed mitosis.

Science.gov (United States)

Takemoto, Ai; Kawashima, Shigehiro A; Li, Juan-Juan; Jeffery, Linda; Yamatsugu, Kenzo; Elemento, Olivier; Nurse, Paul

2016-03-15

Here, we screened a 10,371 library of diverse molecules using a drug-sensitive fission yeast strain to identify compounds which cause defects in chromosome segregation during mitosis. We identified a phosphorium-ylide-based compound Cutin-1 which inhibits nuclear envelope expansion and nuclear elongation during the closed mitosis of fission yeast, and showed that its target is the β-subunit of fatty acid synthase. A point mutation in the dehydratase domain of Fas1 conferred in vivo and in vitro resistance to Cutin-1. Time-lapse photomicrography showed that the bulk of the chromosomes were only transiently separated during mitosis, and nucleoli separation was defective. Subsequently sister chromatids re-associated leading to chromosomal mis-segregation. These segregation defects were reduced when the nuclear volume was increased and were increased when the nuclear volume was reduced. We propose that there needs to be sufficient nuclear volume to allow the nuclear elongation necessary during a closed mitosis to take place for proper chromosome segregation, and that inhibition of fatty acid synthase compromises nuclear elongation and leads to defects in chromosomal segregation. © 2016. Published by The Company of Biologists Ltd.

PICH promotes sister chromatid disjunction and co-operates with topoisomerase II in mitosis

DEFF Research Database (Denmark)

Nielsen, Christian Thomas Friberg; Huttner, Diana; Bizard, Anna H

2015-01-01

PICH is a SNF2 family DNA translocase that binds to ultra-fine DNA bridges (UFBs) in mitosis. Numerous roles for PICH have been proposed from protein depletion experiments, but a consensus has failed to emerge. Here, we report that deletion of PICH in avian cells causes chromosome structural......-193-treated cells. We propose that PICH and Topo II cooperate to prevent chromosome missegregation events in mitosis....

Evolutionary consequences of polyploidy in prokaryotes and the origin of mitosis and meiosis.

Science.gov (United States)

Markov, Alexander V; Kaznacheev, Ilya S

2016-06-08

The origin of eukaryote-specific traits such as mitosis and sexual reproduction remains disputable. There is growing evidence that both mitosis and eukaryotic sex (i.e., the alternation of syngamy and meiosis) may have already existed in the basal eukaryotes. The mating system of the halophilic archaeon Haloferax volcanii probably represents an intermediate stage between typical prokaryotic and eukaryotic sex. H. volcanii is highly polyploid, as well as many other Archaea. Here, we use computer simulation to explore genetic and evolutionary outcomes of polyploidy in amitotic prokaryotes and its possible role in the origin of mitosis, meiosis and eukaryotic sex. Modeling suggests that polyploidy can confer strong short-term evolutionary advantage to amitotic prokaryotes. However, it also promotes the accumulation of recessive deleterious mutations and the risk of extinction in the long term, especially in highly mutagenic environment. There are several possible strategies that amitotic polyploids can use in order to reduce the genetic costs of polyploidy while retaining its benefits. Interestingly, most of these strategies resemble different components or aspects of eukaryotic sex. They include asexual ploidy cycles, equalization of genome copies by gene conversion, high-frequency lateral gene transfer between relatives, chromosome exchange coupled with homologous recombination, and the evolution of more accurate chromosome distribution during cell division (mitosis). Acquisition of mitosis by an amitotic polyploid results in chromosome diversification and specialization. Ultimately, it transforms a polyploid cell into a functionally monoploid one with multiple unique, highly redundant chromosomes. Specialization of chromosomes makes the previously evolved modes of promiscuous chromosome shuffling deleterious. This can result in selective pressure to develop accurate mechanisms of homolog pairing, and, ultimately, meiosis. Emergence of mitosis and the first

Phosphorylation of SAF-A/hnRNP-U Serine 59 by Polo-Like Kinase 1 Is Required for Mitosis.

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Douglas, Pauline; Ye, Ruiqiong; Morrice, Nicholas; Britton, Sébastien; Trinkle-Mulcahy, Laura; Lees-Miller, Susan P

2015-08-01

Scaffold attachment factor A (SAF-A), also called heterogenous nuclear ribonuclear protein U (hnRNP-U), is phosphorylated on serine 59 by the DNA-dependent protein kinase (DNA-PK) in response to DNA damage. Since SAF-A, DNA-PK catalytic subunit (DNA-PKcs), and protein phosphatase 6 (PP6), which interacts with DNA-PKcs, have all been shown to have roles in mitosis, we asked whether DNA-PKcs phosphorylates SAF-A in mitosis. We show that SAF-A is phosphorylated on serine 59 in mitosis, that phosphorylation requires polo-like kinase 1 (PLK1) rather than DNA-PKcs, that SAF-A interacts with PLK1 in nocodazole-treated cells, and that serine 59 is dephosphorylated by protein phosphatase 2A (PP2A) in mitosis. Moreover, cells expressing SAF-A in which serine 59 is mutated to alanine have multiple characteristics of aberrant mitoses, including misaligned chromosomes, lagging chromosomes, polylobed nuclei, and delayed passage through mitosis. Our findings identify serine 59 of SAF-A as a new target of both PLK1 and PP2A in mitosis and reveal that both phosphorylation and dephosphorylation of SAF-A serine 59 by PLK1 and PP2A, respectively, are required for accurate and timely exit from mitosis. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

VISUALIZACIÓN DE LA MITOSIS CON EL MICROSCOPIO DE FUERZA ATÓMICA

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María de Lourdes Segura-Valdez

2008-01-01

Full Text Available En eucariontes, la división celular generalmente ocurre por medio de la mitosis. En estudios previos hemos documentado la posibilidad de estudiar la estructura celular in situ con el microscopio de fuerza atómica, con énfasis en la estructura nuclear en interfase. En este trabajo mostramos que las diferentes etapas de la mitosis pueden ser visualizadas con este instrumento, lo que abre la posibilidad de estudiar este fenómeno en el rango nanométrico.

Mitotic Transcriptional Activation: Clearance of Actively Engaged Pol II via Transcriptional Elongation Control in Mitosis.

Science.gov (United States)

Liang, Kaiwei; Woodfin, Ashley R; Slaughter, Brian D; Unruh, Jay R; Box, Andrew C; Rickels, Ryan A; Gao, Xin; Haug, Jeffrey S; Jaspersen, Sue L; Shilatifard, Ali

2015-11-05

Although it is established that some general transcription factors are inactivated at mitosis, many details of mitotic transcription inhibition (MTI) and its underlying mechanisms are largely unknown. We have identified mitotic transcriptional activation (MTA) as a key regulatory step to control transcription in mitosis for genes with transcriptionally engaged RNA polymerase II (Pol II) to activate and transcribe until the end of the gene to clear Pol II from mitotic chromatin, followed by global impairment of transcription reinitiation through MTI. Global nascent RNA sequencing and RNA fluorescence in situ hybridization demonstrate the existence of transcriptionally engaged Pol II in early mitosis. Both genetic and chemical inhibition of P-TEFb in mitosis lead to delays in the progression of cell division. Together, our study reveals a mechanism for MTA and MTI whereby transcriptionally engaged Pol II can progress into productive elongation and finish transcription to allow proper cellular division. Copyright © 2015 Elsevier Inc. All rights reserved.

The master Greatwall kinase, a critical regulator of mitosis and meiosis.

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Vigneron, Suzanne; Robert, Perle; Hached, Khaled; Sundermann, Lena; Charrasse, Sophie; Labbé, Jean-Claude; Castro, Anna; Lorca, Thierry

2016-01-01

Entry into mitosis requires the coordinated activation of various protein kinases and phosphatases that together activate sequential signaling pathways allowing entry, progression and exit of mitosis. The limiting step is thought to be the activation of the mitotic Cdk1-cyclin B kinase. However, this model has recently evolved with new data showing that in addition to the Cdk1-cyclin B complex, Greatwall (Gwl) kinase is also required to enter into and maintain mitosis. This new concept proposes that entry into mitosis is now based on the combined activation of both kinases Cdk1-cyclin B and Gwl, the former promoting massive phosphorylation of mitotic substrates and the latter inhibiting PP2A-B55 phosphatase responsible for dephosphorylation of these substrates. Activated Gwl phosphorylates both Arpp19 and ENSA, which associate and inhibit PP2A-B55. This pathway seems relatively well conserved from yeast to humans, although some differences appear based on models or techniques used. While Gwl is activated by phosphorylation, its inactivation requires dephosphorylation of critical residues. Several phosphatases such as PP1, PP2A-B55 and FCP1 are required to control the dephosphorylation and inactivation of Gwl and a properly regulated mitotic exit. Gwl has also been reported to be involved in cancer processes and DNA damage recovery. These new findings support the idea that the Gwl-Arpp19/ENSA-PP2A-B55 pathway is essential to achieve an efficient division of cells and to maintain genomic stability.

Ionic liquid mediated stereoselective synthesis of alanine linked hybrid quinazoline-4(3H)-one derivatives perturbing the malarial reductase activity in folate pathway.

Science.gov (United States)

Patel, Tarosh S; Bhatt, Jaimin D; Vanparia, Satish F; Patel, Urmila H; Dixit, Ritu B; Chudasama, Chaitanya J; Patel, Bhavesh D; Dixit, Bharat C

2017-12-15

Grimmel's method was optimized as well as modified leading to the cyclization and incorporation of alanine linked sulphonamide in 4-quinazolin-(3H)-ones. Further, the generation of heterocyclic motif at position-3 of 4-quinazolinones was explored by synthesis of imines, which unfortunately led to an isomeric mixture of stereoisomers. The hurdle of diastereomers encountered on the path was eminently rectified by development of new rapid and reproducible methodology involving the use of imidazolium based ionic liquid as solvents as well as catalyst for cyclization as well as synthesis of imines in situ at position-3 leading to procurement of single E-isomer as the target hybrid heterocyclic molecules. The purity and presence of single isomer was also confirmed by HPLC and spectroscopic techniques. Further, the synthesized sulphonamide linked 4-quinazolin-(3H)-ones hybrids were screened for their antimalarial potency rendering potent entities (4b, 4c, 4 l, 4 t and 4u). The active hybrids were progressively screened for enzyme inhibitory efficacy against presumed receptor Pf-DHFR and h-DHFR computationally as well as in vitro, proving their potency as dihydrofolate reductase inhibitors. The ADME properties of these active molecules were also predicted to enhance the knowhow of the oral bioavailability, indicating good bioavailability of the active entities. Copyright © 2017 Elsevier Ltd. All rights reserved.

Regulation of nuclear envelope dynamics via APC/C is necessary for the progression of semi-open mitosis in Schizosaccharomyces japonicus.

Science.gov (United States)

Aoki, Keita; Shiwa, Yuh; Takada, Hiraku; Yoshikawa, Hirofumi; Niki, Hironori

2013-09-01

Three types of mitosis, which are open, closed or semi-open mitosis, function in eukaryotic cells, respectively. The open mitosis involves breakage of the nuclear envelope before nuclear division, whereas the closed mitosis proceeds with an intact nuclear envelope. To understand the mechanism and significance of three types of mitotic division in eukaryotes, we investigated the process of semi-open mitosis, in which the nuclear envelope is only partially broken, in the fission yeast Schizosaccharomyces japonicus. In anaphase-promoting complex/cyclosome (APC/C) mutants of Sz. japonicus, the nuclear envelope remained relatively intact during anaphase, resulting in impaired semi-open mitosis. As a suppressor of apc2 mutant, a mutation of Oar2, which was a 3-oxoacyl-[acyl carrier protein] reductase, was obtained. The level of the Oar2, which had two destruction-box motifs recognized by APC/C, was increased in APC/C mutants. Furthermore, the defective semi-open mitosis observed in an apc2 mutant was restored by mutated oar2+. Based on these findings, we propose that APC/C regulates the dynamics of the nuclear envelope through degradation of Oar2 dependent on APC/C during the metaphase-to-anaphase transition of semi-open mitosis in Sz. japonicus. © 2013 The Authors Genes to Cells © 2013 by the Molecular Biology Society of Japan and Wiley Publishing Asia Pty Ltd.

Relocalization of human chromatin remodeling cofactor TIP48 in mitosis

International Nuclear Information System (INIS)

Sigala, Barbara; Edwards, Mina; Puri, Teena; Tsaneva, Irina R.

2005-01-01

TIP48 is a highly conserved eukaryotic AAA + protein which is an essential cofactor for several complexes involved in chromatin acetylation and remodeling, transcriptional and developmental regulation and nucleolar organization and trafficking. We show that TIP48 abundance in HeLa cells did not change during the cell cycle, nor did its distribution in various biochemical fractions. However, we observed distinct changes in the subcellular localization of TIP48 during M phase using immunofluorescence microscopy. Our studies demonstrate that in interphase cells TIP48 was found mainly in the nucleus and exhibited a distinct localization in the nuclear periphery. As the cells entered mitosis, TIP48 was excluded from the condensing chromosomes but showed association with the mitotic apparatus. During anaphase, some TIP48 was detected in the centrosome colocalizing with tubulin but the strongest staining appeared in the mitotic equator associated with the midzone central spindle. Accumulation of TIP48 in the midzone and the midbody was observed in late telophase and cytokinesis. This redeployment of TIP48 during anaphase and cytokinesis was independent of microtubule assembly. The relocation of endogenous TIP48 to the midzone/midbody under physiological conditions suggests a novel and distinct function for TIP48 in mitosis and possible involvement in the exit of mitosis

Polo-like kinase 1 inhibits DNA damage response during mitosis.

Science.gov (United States)

Benada, Jan; Burdová, Kamila; Lidak, Tomáš; von Morgen, Patrick; Macurek, Libor

2015-01-01

In response to genotoxic stress, cells protect their genome integrity by activation of a conserved DNA damage response (DDR) pathway that coordinates DNA repair and progression through the cell cycle. Extensive modification of the chromatin flanking the DNA lesion by ATM kinase and RNF8/RNF168 ubiquitin ligases enables recruitment of various repair factors. Among them BRCA1 and 53BP1 are required for homologous recombination and non-homologous end joining, respectively. Whereas mechanisms of DDR are relatively well understood in interphase cells, comparatively less is known about organization of DDR during mitosis. Although ATM can be activated in mitotic cells, 53BP1 is not recruited to the chromatin until cells exit mitosis. Here we report mitotic phosphorylation of 53BP1 by Plk1 and Cdk1 that impairs the ability of 53BP1 to bind the ubiquitinated H2A and to properly localize to the sites of DNA damage. Phosphorylation of 53BP1 at S1618 occurs at kinetochores and in cytosol and is restricted to mitotic cells. Interaction between 53BP1 and Plk1 depends on the activity of Cdk1. We propose that activity of Cdk1 and Plk1 allows spatiotemporally controlled suppression of 53BP1 function during mitosis.

Direct evidence that radiation induced micronuclei of early embryos require a mitosis for expression

International Nuclear Information System (INIS)

Mueller, W.U.; Schlusen, I.; Streffer, C.

1991-01-01

The naturally synchronous development of early mouse embryos was exploited to address the question, whether micronuclei require a mitosis for expression or whether they can be expressed in the same cell cycle, in which exposure to X-rays or caffeine took place. Experiments with 2-cell and with 4-cell embryos showed that micronulcei are expressed only if a mitosis is completed. There was no indication, even after doses up to 20 Gy, that micronuclei can be expressed before the mitosis was reached, which followed exposure. Furthermore, no nuclear fragmentation pointing to apoptosis could be detected in the cycle, in which cells were exposed. The same results were obtained when caffeine (5 mM) was used as micronucleus inducing agent. (orig.)

The mitosis-regulating and protein-protein interaction activities of astrin are controlled by aurora-A-induced phosphorylation.

Science.gov (United States)

Chiu, Shao-Chih; Chen, Jo-Mei Maureen; Wei, Tong-You Wade; Cheng, Tai-Shan; Wang, Ya-Hui Candice; Ku, Chia-Feng; Lian, Chiao-Hsuan; Liu, Chun-Chih Jared; Kuo, Yi-Chun; Yu, Chang-Tze Ricky

2014-09-01

Cells display dramatic morphological changes in mitosis, where numerous factors form regulatory networks to orchestrate the complicated process, resulting in extreme fidelity of the segregation of duplicated chromosomes into two daughter cells. Astrin regulates several aspects of mitosis, such as maintaining the cohesion of sister chromatids by inactivating Separase and stabilizing spindle, aligning and segregating chromosomes, and silencing spindle assembly checkpoint by interacting with Src kinase-associated phosphoprotein (SKAP) and cytoplasmic linker-associated protein-1α (CLASP-1α). To understand how Astrin is regulated in mitosis, we report here that Astrin acts as a mitotic phosphoprotein, and Aurora-A phosphorylates Astrin at Ser(115). The phosphorylation-deficient mutant Astrin S115A abnormally activates spindle assembly checkpoint and delays mitosis progression, decreases spindle stability, and induces chromosome misalignment. Mechanistic analyses reveal that Astrin phosphorylation mimicking mutant S115D, instead of S115A, binds and induces ubiquitination and degradation of securin, which sequentially activates Separase, an enzyme required for the separation of sister chromatids. Moreover, S115A fails to bind mitosis regulators, including SKAP and CLASP-1α, which results in the mitotic defects observed in Astrin S115A-transfected cells. In conclusion, Aurora-A phosphorylates Astrin and guides the binding of Astrin to its cellular partners, which ensures proper progression of mitosis. Copyright © 2014 the American Physiological Society.

The study of UV-spectra of the sodium (3-oxo-3,4-dihydro-2H-[1,2,4]triazino[4,3-c]quinazolin-4-ylacetate

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О. V. Kryvoshey

2016-04-01

Full Text Available Despite the potential of [1,2,4]triazino[4,3-c]quinazoline derivatives as promising bioactive compounds, their electronic spectra has not been studied. Present manuscript is aimed to the estimation of relationships of molecules structure with the nature of their UV-spectra and identifying spectral patterns of pharmacophore that determines the pharmacological activity of the substance. Mentioned information undoubtedly contributes to the development of the theory of the purposeful synthesis of organic compounds. Methods and results. UV-spectra of sodium (3-oxo-3,4-dihydro-2H-[1,2,4]triazino[4,3-c]quinazolin-4-ylacetate in different polarity solvents have been studied. It allowed to identify types of electron transitions, which were responsible of emergence of the observed absorption bands. Conclusions. It was found that the UV-spectra of the studied compounds in solvents with different polarity were characterized by three absorption bands in the range 190–227 nm, 260–284 nm and 328–348 nm. According to Braude classification the first absorption band should be classified as 1La, the second – as 1Lb, and the third band is due to p-π- conjugation in the molecule of the whole molecule structure.

MiR-210 disturbs mitotic progression through regulating a group of mitosis-related genes.

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He, Jie; Wu, Jiangbin; Xu, Naihan; Xie, Weidong; Li, Mengnan; Li, Jianna; Jiang, Yuyang; Yang, Burton B; Zhang, Yaou

2013-01-07

MiR-210 is up-regulated in multiple cancer types but its function is disputable and further investigation is necessary. Using a bioinformatics approach, we identified the putative target genes of miR-210 in hypoxia-induced CNE cells from genome-wide scale. Two functional gene groups related to cell cycle and RNA processing were recognized as the major targets of miR-210. Here, we investigated the molecular mechanism and biological consequence of miR-210 in cell cycle regulation, particularly mitosis. Hypoxia-induced up-regulation of miR-210 was highly correlated with the down-regulation of a group of mitosis-related genes, including Plk1, Cdc25B, Cyclin F, Bub1B and Fam83D. MiR-210 suppressed the expression of these genes by directly targeting their 3'-UTRs. Over-expression of exogenous miR-210 disturbed mitotic progression and caused aberrant mitosis. Furthermore, miR-210 mimic with pharmacological doses reduced tumor formation in a mouse metastatic tumor model. Taken together, these results implicate that miR-210 disturbs mitosis through targeting multi-genes involved in mitotic progression, which may contribute to its inhibitory role on tumor formation.

Expression of HSF2 decreases in mitosis to enable stress-inducible transcription and cell survival

Science.gov (United States)

Elsing, Alexandra N.; Aspelin, Camilla; Björk, Johanna K.; Bergman, Heidi A.; Himanen, Samu V.; Kallio, Marko J.; Roos-Mattjus, Pia

2014-01-01

Unless mitigated, external and physiological stresses are detrimental for cells, especially in mitosis, resulting in chromosomal missegregation, aneuploidy, or apoptosis. Heat shock proteins (Hsps) maintain protein homeostasis and promote cell survival. Hsps are transcriptionally regulated by heat shock factors (HSFs). Of these, HSF1 is the master regulator and HSF2 modulates Hsp expression by interacting with HSF1. Due to global inhibition of transcription in mitosis, including HSF1-mediated expression of Hsps, mitotic cells are highly vulnerable to stress. Here, we show that cells can counteract transcriptional silencing and protect themselves against proteotoxicity in mitosis. We found that the condensed chromatin of HSF2-deficient cells is accessible for HSF1 and RNA polymerase II, allowing stress-inducible Hsp expression. Consequently, HSF2-deficient cells exposed to acute stress display diminished mitotic errors and have a survival advantage. We also show that HSF2 expression declines during mitosis in several but not all human cell lines, which corresponds to the Hsp70 induction and protection against stress-induced mitotic abnormalities and apoptosis. PMID:25202032

Duck hepatitis B virus covalently closed circular DNA appears to survive hepatocyte mitosis in the growing liver

International Nuclear Information System (INIS)

Reaiche-Miller, Georget Y.; Thorpe, Michael; Low, Huey Chi; Qiao, Qiao; Scougall, Catherine A.; Mason, William S.; Litwin, Samuel; Jilbert, Allison R.

2013-01-01

Nucleos(t)ide analogues that inhibit hepatitis B virus (HBV) DNA replication are typically used as monotherapy for chronically infected patients. Treatment with a nucleos(t)ide analogue eliminates most HBV DNA replication intermediates and produces a gradual decline in levels of covalently closed circular DNA (cccDNA), the template for viral RNA synthesis. It remains uncertain if levels of cccDNA decline primarily through hepatocyte death, or if loss also occurs during hepatocyte mitosis. To determine if cccDNA survives mitosis, growing ducklings infected with duck hepatitis B virus (DHBV) were treated with the nucleoside analogue, Entecavir. Viremia was suppressed at least 10 5 -fold, during a period when average liver mass increased 23-fold. Analysis of the data suggested that if cccDNA synthesis was completely inhibited, at least 49% of cccDNA survived hepatocyte mitosis. However, there was a large duck-to-duck variation in cccDNA levels, suggesting that low level cccDNA synthesis may contribute to this apparent survival through mitosis. - Highlights: • The hepatitis B virus nuclear template is covalently closed circular DNA (cccDNA). • cccDNA was studied during liver growth in duck hepatitis B virus infected ducks. • Virus DNA replication and new cccDNA synthesis were inhibited with Entecavir. • At least 49% of cccDNA appeared to survive hepatocyte mitosis. • Low level virus DNA synthesis may contribute to survival of cccDNA through mitosis

Duck hepatitis B virus covalently closed circular DNA appears to survive hepatocyte mitosis in the growing liver

Energy Technology Data Exchange (ETDEWEB)

Reaiche-Miller, Georget Y.; Thorpe, Michael; Low, Huey Chi; Qiao, Qiao; Scougall, Catherine A. [School of Molecular and Biomedical Science, University of Adelaide, Adelaide, SA 5005 (Australia); Mason, William S.; Litwin, Samuel [Institute for Cancer Research, Fox Chase Cancer Center, Philadelphia, PA 19111 (United States); Jilbert, Allison R., E-mail: allison.jilbert@adelaide.edu.au [School of Molecular and Biomedical Science, University of Adelaide, Adelaide, SA 5005 (Australia)

2013-11-15

Nucleos(t)ide analogues that inhibit hepatitis B virus (HBV) DNA replication are typically used as monotherapy for chronically infected patients. Treatment with a nucleos(t)ide analogue eliminates most HBV DNA replication intermediates and produces a gradual decline in levels of covalently closed circular DNA (cccDNA), the template for viral RNA synthesis. It remains uncertain if levels of cccDNA decline primarily through hepatocyte death, or if loss also occurs during hepatocyte mitosis. To determine if cccDNA survives mitosis, growing ducklings infected with duck hepatitis B virus (DHBV) were treated with the nucleoside analogue, Entecavir. Viremia was suppressed at least 10{sup 5}-fold, during a period when average liver mass increased 23-fold. Analysis of the data suggested that if cccDNA synthesis was completely inhibited, at least 49% of cccDNA survived hepatocyte mitosis. However, there was a large duck-to-duck variation in cccDNA levels, suggesting that low level cccDNA synthesis may contribute to this apparent survival through mitosis. - Highlights: • The hepatitis B virus nuclear template is covalently closed circular DNA (cccDNA). • cccDNA was studied during liver growth in duck hepatitis B virus infected ducks. • Virus DNA replication and new cccDNA synthesis were inhibited with Entecavir. • At least 49% of cccDNA appeared to survive hepatocyte mitosis. • Low level virus DNA synthesis may contribute to survival of cccDNA through mitosis.

A new theory of the origin of cancer: quantum coherent entanglement, centrioles, mitosis, and differentiation.

Science.gov (United States)

Hameroff, Stuart R

2004-11-01

Malignant cells are characterized by abnormal segregation of chromosomes during mitosis ("aneuploidy"), generally considered a result of malignancy originating in genetic mutations. However, recent evidence supports a century-old concept that maldistribution of chromosomes (and resultant genomic instability) due to abnormalities in mitosis itself is the primary cause of malignancy rather than a mere byproduct. In normal mitosis chromosomes replicate into sister chromatids which are then precisely separated and transported into mirror-like sets by structural protein assemblies called mitotic spindles and centrioles, both composed of microtubules. The elegant yet poorly understood ballet-like movements and geometric organization occurring in mitosis have suggested guidance by some type of organizing field, however neither electromagnetic nor chemical gradient fields have been demonstrated or shown to be sufficient. It is proposed here that normal mirror-like mitosis is organized by quantum coherence and quantum entanglement among microtubule-based centrioles and mitotic spindles which ensure precise, complementary duplication of daughter cell genomes and recognition of daughter cell boundaries. Evidence and theory supporting organized quantum states in cytoplasm/nucleoplasm (and quantum optical properties of centrioles in particular) at physiological temperature are presented. Impairment of quantum coherence and/or entanglement among microtubule-based mitotic spindles and centrioles can result in abnormal distribution of chromosomes, abnormal differentiation and uncontrolled growth, and account for all aspects of malignancy. New approaches to cancer therapy and stem cell production are suggested via non-thermal laser-mediated effects aimed at quantum optical states of centrioles.

Systematic Analysis of the Crosstalk between Mitosis and DNA Damage by a Live Cell siRNA Screen

DEFF Research Database (Denmark)

Pedersen, Ronni Sølvhøi

Recent research has shown, that the biological processes of DNA replication, DNA damage, cell cycle and mitosis cannot be considered as isolated cellular functions but are mechanistically linked in many ways. For instance, when cells are exposed to replication stress and enter mitosis...... propose that this strong p53 response, which often occurs without detectable increase in DNA damage, is caused by the acute increase in chromosomal aneuploidy. Finally, our systematic approach to the DNA damage-mitosis crosstalk reveals widespread cell death in response to mitotic pertubations, showing...

Cycling with BRCA2 from DNA repair to mitosis

International Nuclear Information System (INIS)

Lee, Hyunsook

2014-01-01

Genetic integrity in proliferating cells is guaranteed by the harmony of DNA replication, appropriate DNA repair, and segregation of the duplicated genome. Breast cancer susceptibility gene BRCA2 is a unique tumor suppressor that is involved in all three processes. Hence, it is critical in genome maintenance. The functions of BRCA2 in DNA repair and homology-directed recombination (HDR) have been reviewed numerous times. Here, I will briefly go through the functions of BRCA2 in HDR and focus on the emerging roles of BRCA2 in telomere homeostasis and mitosis, then discuss how BRCA2 exerts distinct functions in a cell-cycle specific manner in the maintenance of genomic integrity. - Highlights: • BRCA2 is a multifaceted tumor suppressor and is crucial in genetic integrity. • BRCA2 exerts distinct functions in cell cycle-specific manner. • Mitotic kinases regulate diverse functions of BRCA2 in mitosis and cytokinesis

Cycling with BRCA2 from DNA repair to mitosis

Energy Technology Data Exchange (ETDEWEB)

Lee, Hyunsook, E-mail: HL212@snu.ac.kr

2014-11-15

Genetic integrity in proliferating cells is guaranteed by the harmony of DNA replication, appropriate DNA repair, and segregation of the duplicated genome. Breast cancer susceptibility gene BRCA2 is a unique tumor suppressor that is involved in all three processes. Hence, it is critical in genome maintenance. The functions of BRCA2 in DNA repair and homology-directed recombination (HDR) have been reviewed numerous times. Here, I will briefly go through the functions of BRCA2 in HDR and focus on the emerging roles of BRCA2 in telomere homeostasis and mitosis, then discuss how BRCA2 exerts distinct functions in a cell-cycle specific manner in the maintenance of genomic integrity. - Highlights: • BRCA2 is a multifaceted tumor suppressor and is crucial in genetic integrity. • BRCA2 exerts distinct functions in cell cycle-specific manner. • Mitotic kinases regulate diverse functions of BRCA2 in mitosis and cytokinesis.

Mitosis, diffusible crosslinkers, and the ideal gas law.

Science.gov (United States)

Odde, David J

2015-03-12

During mitosis, molecular motors hydrolyze ATP to generate sliding forces between adjacent microtubules and form the bipolar mitotic spindle. Lansky et al. now show that the diffusible microtubule crosslinker Ase1p can generate sliding forces between adjacent microtubules, and it does so without ATP hydrolysis. Copyright © 2015 Elsevier Inc. All rights reserved.

Seasonal temperature variations influence tapetum mitosis patterns associated with reproductive fitness.

Science.gov (United States)

Lavania, Umesh C; Basu, Surochita; Kushwaha, Jyotsana Singh; Lavania, Seshu

2014-09-01

Environmental stress in plants impacts many biological processes, including male gametogenesis, and affects several cytological mechanisms that are strongly interrelated. To understand the likely impact of rising temperature on reproductive fitness in the climate change regime, a study of tapetal mitosis and its accompanying meiosis over seasons was made to elucidate the influence of temperature change on the cytological events occurring during microsporogenesis. For this we used two species of an environmentally sensitive plant system, i.e., genus Cymbopogon Sprengel (Poaceae), namely Cymbopogon nardus (L.) Rendle var. confertiflorus (Steud.) Bor (2n = 20) and Cymbopogon jwaruncusha (Jones) Schult. (2n = 20). Both species flower profusely during extreme summer (48 °C) and mild winter (15 °C) but support low and high seed fertility, respectively, in the two seasons. We have shown that tapetal mitotic patterns over seasons entail differential behavior for tapetal mitosis. During the process of tapetum development there are episodes of endomitosis that form either (i) an endopolyploid genomically imbalanced uninucleate and multinucleate tapetum, and (or) (ii) an acytokinetic multinucleate genomically balanced tapetum, with the progression of meiosis in the accompanying sporogenous tissue. The relative frequency of occurrence of the two types of tapetum mitosis patterns is significantly different in the two seasons, and it is found to be correlated with the temperature conditions. Whereas, the former (genomically imbalanced tapetum) are prevalent during the hot summer, the latter (genomically balanced tapetum) are frequent under optimal conditions. Such a differential behaviour in tapetal mitosis vis-à-vis temperature change is also correspondingly accompanied by substantial disturbances or regularity in meiotic anaphase disjunction. Both species show similar patterns. The study underpins that tapetal mitotic behaviour per se could be a reasonable indicator to

Recent advances in the structural library of functionalized quinazoline and quinazolinone scaffolds: synthetic approaches and multifarious applications.

Science.gov (United States)

Khan, Imtiaz; Ibrar, Aliya; Abbas, Naeem; Saeed, Aamer

2014-04-09

Drug development has been a principal driving force in the rapid maturation of the field of medicinal chemistry during the past several decades. During this period, the intriguing and challenging molecular architectures of nitrogen-containing heterocycles with potential bioactive properties have received significant attention from researchers engaged in the areas of natural product synthesis and heterocyclic methodology, and constituted a continuous stimulus for development in bio(organic) chemistry. In this perspective, the current review article is an effort to summarize recent developments in the environmentally benign synthetic methods providing access to quinazoline and quinazolinone scaffolds with promising biological potential. This article also aims to discuss potential future directions on the development of more potent and specific analogues for various biological targets. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Restraint of apoptosis during mitosis through interdomain phosphorylation of caspase-2

Science.gov (United States)

Andersen, Joshua L; Johnson, Carrie E; Freel, Christopher D; Parrish, Amanda B; Day, Jennifer L; Buchakjian, Marisa R; Nutt, Leta K; Thompson, J Will; Moseley, M Arthur; Kornbluth, Sally

2009-01-01

The apoptotic initiator caspase-2 has been implicated in oocyte death, in DNA damage- and heat shock-induced death, and in mitotic catastrophe. We show here that the mitosis-promoting kinase, cdk1–cyclin B1, suppresses apoptosis upstream of mitochondrial cytochrome c release by phosphorylating caspase-2 within an evolutionarily conserved sequence at Ser 340. Phosphorylation of this residue, situated in the caspase-2 interdomain, prevents caspase-2 activation. S340 was susceptible to phosphatase 1 dephosphorylation, and an interaction between phosphatase 1 and caspase-2 detected during interphase was lost in mitosis. Expression of S340A non-phosphorylatable caspase-2 abrogated mitotic suppression of caspase-2 and apoptosis in various settings, including oocytes induced to undergo cdk1-dependent maturation. Moreover, U2OS cells treated with nocodazole were found to undergo mitotic catastrophe more readily when endogenous caspase-2 was replaced with the S340A mutant to lift mitotic inhibition. These data demonstrate that for apoptotic stimuli transduced by caspase-2, cell death is prevented during mitosis through the inhibitory phosphorylation of caspase-2 and suggest that under conditions of mitotic arrest, cdk1–cyclin B1 activity must be overcome for apoptosis to occur. PMID:19730412

Downregulation of Wip1 phosphatase modulates the cellular threshold of DNA damage signaling in mitosis

Science.gov (United States)

Macurek, Libor; Benada, Jan; Müllers, Erik; Halim, Vincentius A.; Krejčíková, Kateřina; Burdová, Kamila; Pecháčková, Sona; Hodný, Zdeněk; Lindqvist, Arne; Medema, René H.; Bartek, Jiri

2013-01-01

Cells are constantly challenged by DNA damage and protect their genome integrity by activation of an evolutionary conserved DNA damage response pathway (DDR). A central core of DDR is composed of a spatiotemporally ordered net of post-translational modifications, among which protein phosphorylation plays a major role. Activation of checkpoint kinases ATM/ATR and Chk1/2 leads to a temporal arrest in cell cycle progression (checkpoint) and allows time for DNA repair. Following DNA repair, cells re-enter the cell cycle by checkpoint recovery. Wip1 phosphatase (also called PPM1D) dephosphorylates multiple proteins involved in DDR and is essential for timely termination of the DDR. Here we have investigated how Wip1 is regulated in the context of the cell cycle. We found that Wip1 activity is downregulated by several mechanisms during mitosis. Wip1 protein abundance increases from G1 phase to G2 and declines in mitosis. Decreased abundance of Wip1 during mitosis is caused by proteasomal degradation. In addition, Wip1 is phosphorylated at multiple residues during mitosis, and this leads to inhibition of its enzymatic activity. Importantly, ectopic expression of Wip1 reduced γH2AX staining in mitotic cells and decreased the number of 53BP1 nuclear bodies in G1 cells. We propose that the combined decrease and inhibition of Wip1 in mitosis decreases the threshold necessary for DDR activation and enables cells to react adequately even to modest levels of DNA damage encountered during unperturbed mitotic progression. PMID:23255129

53BP1 and USP28 mediate p53-dependent cell cycle arrest in response to centrosome loss and prolonged mitosis.

Science.gov (United States)

Fong, Chii Shyang; Mazo, Gregory; Das, Tuhin; Goodman, Joshua; Kim, Minhee; O'Rourke, Brian P; Izquierdo, Denisse; Tsou, Meng-Fu Bryan

2016-07-02

Mitosis occurs efficiently, but when it is disturbed or delayed, p53-dependent cell death or senescence is often triggered after mitotic exit. To characterize this process, we conducted CRISPR-mediated loss-of-function screens using a cell-based assay in which mitosis is consistently disturbed by centrosome loss. We identified 53BP1 and USP28 as essential components acting upstream of p53, evoking p21-dependent cell cycle arrest in response not only to centrosome loss, but also to other distinct defects causing prolonged mitosis. Intriguingly, 53BP1 mediates p53 activation independently of its DNA repair activity, but requiring its interacting protein USP28 that can directly deubiquitinate p53 in vitro and ectopically stabilize p53 in vivo. Moreover, 53BP1 can transduce prolonged mitosis to cell cycle arrest independently of the spindle assembly checkpoint (SAC), suggesting that while SAC protects mitotic accuracy by slowing down mitosis, 53BP1 and USP28 function in parallel to select against disturbed or delayed mitosis, promoting mitotic efficiency.

Uncoupling of S phase and mitosis in cardiomyocytes and hepatocytes lacking the winged-helix transcription factor Trident

NARCIS (Netherlands)

Korver, W.; Schilham, M. W.; Moerer, P.; van den Hoff, M. J.; Dam, K.; Lamers, W. H.; Medema, R. H.; Clevers, H.

1998-01-01

In order to maintain a stable karyotype, the eukaryotic cell cycle is coordinated such that only one round of S phase precedes each mitosis, and mitosis is not initiated until DNA replication is completed. Several checkpoints and regulatory proteins have been defined in lower eukaryotes that govern

Unsuccessful mitosis in multicellular tumour spheroids.

Science.gov (United States)

Molla, Annie; Couvet, Morgane; Coll, Jean-Luc

2017-04-25

Multicellular spheroids are very attractive models in oncology because they mimic the 3D organization of the tumour cells with their microenvironment. We show here using 3 different cell types (mammary TSA/pc, embryonic kidney Hek293 and cervical cancer HeLa), that when the cells are growing as spheroids the frequency of binucleated cells is augmented as occurs in some human tumours.We therefore describe mitosis in multicellular spheroids by following mitotic markers and by time-lapse experiments. Chromosomes alignment appears to be correct on the metaphasic plate and the passenger complex is well localized on centromere. Moreover aurora kinases are fully active and histone H3 is phosphorylated on Ser 10. Consequently, the mitotic spindle checkpoint is satisfied and, anaphase proceeds as illustrated by the transfer of survivin on the spindle and by the segregation of the two lots of chromosomes. However, the segregation plane is not well defined and oscillations of the dividing cells are observed. Finally, cytokinesis fails and the absence of separation of the two daughter cells gives rise to binucleated cells.Division orientation is specified during interphase and persists throughout mitosis. Our data indicate that the cancer cells, in multicellular spheroids, lose their ability to regulate their orientation, a feature commonly encountered in tumours.Moreover, multicellular spheroid expansion is still sensitive to mitotic drugs as pactlitaxel and aurora kinase inhibitors. The spheroids thus represent a highly relevant model for studying drug efficiency in tumours.

PLK1 Activation in Late G2 Sets Up Commitment to Mitosis.

Science.gov (United States)

Gheghiani, Lilia; Loew, Damarys; Lombard, Bérangère; Mansfeld, Jörg; Gavet, Olivier

2017-06-06

Commitment to mitosis must be tightly coordinated with DNA replication to preserve genome integrity. While we have previously established that the timely activation of CyclinB1-Cdk1 in late G2 triggers mitotic entry, the upstream regulatory mechanisms remain unclear. Here, we report that Polo-like kinase 1 (Plk1) is required for entry into mitosis during an unperturbed cell cycle and is rapidly activated shortly before CyclinB1-Cdk1. We determine that Plk1 associates with the Cdc25C1 phosphatase and induces its phosphorylation before mitotic entry. Plk1-dependent Cdc25C1 phosphosites are sufficient to promote mitotic entry, even when Plk1 activity is inhibited. Furthermore, we find that activation of Plk1 during G2 relies on CyclinA2-Cdk activity levels. Our findings thus elucidate a critical role for Plk1 in CyclinB1-Cdk1 activation and mitotic entry and outline how CyclinA2-Cdk, an S-promoting factor, poises cells for commitment to mitosis. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Real-time fluorescence imaging of the DNA damage repair response during mitosis.

Science.gov (United States)

Miwa, Shinji; Yano, Shuya; Yamamoto, Mako; Matsumoto, Yasunori; Uehara, Fuminari; Hiroshima, Yukihiko; Toneri, Makoto; Murakami, Takashi; Kimura, Hiroaki; Hayashi, Katsuhiro; Yamamoto, Norio; Efimova, Elena V; Tsuchiya, Hiroyuki; Hoffman, Robert M

2015-04-01

The response to DNA damage during mitosis was visualized using real-time fluorescence imaging of focus formation by the DNA-damage repair (DDR) response protein 53BP1 linked to green fluorescent protein (GFP) (53BP1-GFP) in the MiaPaCa-2(Tet-On) pancreatic cancer cell line. To observe 53BP1-GFP foci during mitosis, MiaPaCa-2(Tet-On) 53BP1-GFP cells were imaged every 30 min by confocal microscopy. Time-lapse imaging demonstrated that 11.4 ± 2.1% of the mitotic MiaPaCa-2(Tet-On) 53BP1-GFP cells had increased focus formation over time. Non-mitotic cells did not have an increase in 53BP1-GFP focus formation over time. Some of the mitotic MiaPaCa-2(Tet-On) 53BP1-GFP cells with focus formation became apoptotic. The results of the present report suggest that DNA strand breaks occur during mitosis and undergo repair, which may cause some of the mitotic cells to enter apoptosis in a phenomenon possibly related to mitotic catastrophe. © 2014 Wiley Periodicals, Inc.

Incoming human papillomavirus type 16 genome resides in a vesicular compartment throughout mitosis.

Science.gov (United States)

DiGiuseppe, Stephen; Luszczek, Wioleta; Keiffer, Timothy R; Bienkowska-Haba, Malgorzata; Guion, Lucile G M; Sapp, Martin J

2016-05-31

During the entry process, the human papillomavirus (HPV) capsid is trafficked to the trans-Golgi network (TGN), whereupon it enters the nucleus during mitosis. We previously demonstrated that the minor capsid protein L2 assumes a transmembranous conformation in the TGN. Here we provide evidence that the incoming viral genome dissociates from the TGN and associates with microtubules after the onset of mitosis. Deposition onto mitotic chromosomes is L2-mediated. Using differential staining of an incoming viral genome by small molecular dyes in selectively permeabilized cells, nuclease protection, and flotation assays, we found that HPV resides in a membrane-bound vesicle until mitosis is completed and the nuclear envelope has reformed. As a result, expression of the incoming viral genome is delayed. Taken together, these data provide evidence that HPV has evolved a unique strategy for delivering the viral genome to the nucleus of dividing cells. Furthermore, it is unlikely that nuclear vesicles are unique to HPV, and thus we may have uncovered a hitherto unrecognized cellular pathway that may be of interest for future cell biological studies.

Study of antileishmanial activity of 2-aminobenzoyl amino acid hydrazides and their quinazoline derivatives.

Science.gov (United States)

Khattab, Sherine Nabil; Haiba, Nesreen Saied; Asal, Ahmed Mosaad; Bekhit, Adnan A; Guemei, Aida A; Amer, Adel; El-Faham, Ayman

2017-02-15

A new small library of 2-aminobenzoyl amino acid hydrazide derivatives and quinazolinones derivatives was synthesized and fully characterized by IR, NMR, and elemental analysis. The activity of the prepared compounds on the growth of Leishmania aethiopica promastigotes was evaluated. 2-Benzoyl amino acid hydrazide showed higher inhibitory effect than the quinazoline counterpart. The in vitro antipromastigote activity demonstrated that compounds 2a, 2b, 2f and 4a had IC 50 better than standard drug miltefosine and comparable activity to amphotericin B deoxycholate, which indicates their high antileishmanial activity against Leishmania. aethiopica. Among the prepared compounds; 2-amino-N-(6-hydrazinyl-6-oxohexyl)benzamide 2f (IC 50 =0.051μM) has the best activity, 154 folds more active than reference standard drug miltefosine (IC 50 =7.832μM), and half fold the activity of amphotericin B (IC 50 =0.035μM). In addition, this compound was safe and well tolerated by experimental animals orally up to 250mg/kg and parenterally up to 100mg/kg. Copyright © 2017 Elsevier Ltd. All rights reserved.

Radiation block of bone marrow cell mitoses and the effect of insulin

Energy Technology Data Exchange (ETDEWEB)

Barkalaya, A I

1976-01-01

Insulin (0.15 - 0.2 units/kg) has been administered to white rats immediately after the exposure to 750 R, at the background of hypercorticoidism. This resulted in the inhibition of the development of the post-irradiation-stress-hyperglycemia; and the mitotic index of the bone marrow cells at the time of the mitosis block was higher than in the control irradiated rats. Insulin administration at the peak of radiation sickness during hypercorticoidism levelled hyperglycemia, stimulated the mitotic activity of cells of the bone marrow and the regeneration of the latter.

Cdc15 Phosphorylates the C-terminal Domain of RNA Polymerase II for Transcription during Mitosis.

Science.gov (United States)

Singh, Amit Kumar; Rastogi, Shivangi; Shukla, Harish; Asalam, Mohd; Rath, Srikanta Kumar; Akhtar, Md Sohail

2017-03-31

In eukaryotes, the basal transcription in interphase is orchestrated through the regulation by kinases (Kin28, Bur1, and Ctk1) and phosphatases (Ssu72, Rtr1, and Fcp1), which act through the post-translational modification of the C-terminal domain (CTD) of the largest subunit of RNA polymerase II. The CTD comprises the repeated Tyr-Ser-Pro-Thr-Ser-Pro-Ser motif with potential epigenetic modification sites. Despite the observation of transcription and periodic expression of genes during mitosis with entailing CTD phosphorylation and dephosphorylation, the associated CTD specific kinase(s) and its role in transcription remains unknown. Here we have identified Cdc15 as a potential kinase phosphorylating Ser-2 and Ser-5 of CTD for transcription during mitosis in the budding yeast. The phosphorylation of CTD by Cdc15 is independent of any prior Ser phosphorylation(s). The inactivation of Cdc15 causes reduction of global CTD phosphorylation during mitosis and affects the expression of genes whose transcript levels peak during mitosis. Cdc15 also influences the complete transcription of clb2 gene and phosphorylates Ser-5 at the promoter and Ser-2 toward the 3' end of the gene. The observation that Cdc15 could phosphorylate Ser-5, as well as Ser-2, during transcription in mitosis is in contrast to the phosphorylation marks put by the kinases in interphase (G 1 , S, and G 2 ), where Cdck7/Kin28 phosphorylates Ser-5 at promoter and Bur1/Ctk1 phosphorylates Ser-2 at the 3' end of the genes. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Optimization of 2-Anilino 4-Amino Substituted Quinazolines into Potent Antimalarial Agents with Oral in Vivo Activity.

Science.gov (United States)

Gilson, Paul R; Tan, Cyrus; Jarman, Kate E; Lowes, Kym N; Curtis, Joan M; Nguyen, William; Di Rago, Adrian E; Bullen, Hayley E; Prinz, Boris; Duffy, Sandra; Baell, Jonathan B; Hutton, Craig A; Jousset Subroux, Helene; Crabb, Brendan S; Avery, Vicky M; Cowman, Alan F; Sleebs, Brad E

2017-02-09

Novel antimalarial therapeutics that target multiple stages of the parasite lifecycle are urgently required to tackle the emerging problem of resistance with current drugs. Here, we describe the optimization of the 2-anilino quinazoline class as antimalarial agents. The class, identified from publicly available antimalarial screening data, was optimized to generate lead compounds that possess potent antimalarial activity against P. falciparum parasites comparable to the known antimalarials, chloroquine and mefloquine. During the optimization process, we defined the functionality necessary for activity and improved in vitro metabolism and solubility. The resultant lead compounds possess potent activity against a multidrug resistant strain of P. falciparum and arrest parasites at the ring phase of the asexual stage and also gametocytogensis. Finally, we show that the lead compounds are orally efficacious in a 4 day murine model of malaria disease burden.

Ase1p Organizes Antiparallel Microtubule Arrays during Interphase and Mitosis in Fission YeastV⃞

OpenAIRE

Loïodice, Isabelle; Staub, Jayme; Setty, Thanuja Gangi; Nguyen, Nam-Phuong T.; Paoletti, Anne; Tran, P. T.

2005-01-01

Proper microtubule organization is essential for cellular processes such as organelle positioning during interphase and spindle formation during mitosis. The fission yeast Schizosaccharomyces pombe presents a good model for understanding microtubule organization. We identify fission yeast ase1p, a member of the conserved ASE1/PRC1/MAP65 family of microtubule bundling proteins, which functions in organizing the spindle midzone during mitosis. Using fluorescence live cell imaging, we show that ...

Polo-like kinase 1 (PLK1) and protein phosphatase 6 (PP6) regulate DNA-dependent protein kinase catalytic subunit (DNA-PKcs) phosphorylation in mitosis.

Science.gov (United States)

Douglas, Pauline; Ye, Ruiqiong; Trinkle-Mulcahy, Laura; Neal, Jessica A; De Wever, Veerle; Morrice, Nick A; Meek, Katheryn; Lees-Miller, Susan P

2014-06-25

The protein kinase activity of the DNA-PKcs (DNA-dependent protein kinase catalytic subunit) and its autophosphorylation are critical for DBS (DNA double-strand break) repair via NHEJ (non-homologous end-joining). Recent studies have shown that depletion or inactivation of DNA-PKcs kinase activity also results in mitotic defects. DNA-PKcs is autophosphorylated on Ser2056, Thr2647 and Thr2609 in mitosis and phosphorylated DNA-PKcs localize to centrosomes, mitotic spindles and the midbody. DNA-PKcs also interacts with PP6 (protein phosphatase 6), and PP6 has been shown to dephosphorylate Aurora A kinase in mitosis. Here we report that DNA-PKcs is phosphorylated on Ser3205 and Thr3950 in mitosis. Phosphorylation of Thr3950 is DNA-PK-dependent, whereas phosphorylation of Ser3205 requires PLK1 (polo-like kinase 1). Moreover, PLK1 phosphorylates DNA-PKcs on Ser3205 in vitro and interacts with DNA-PKcs in mitosis. In addition, PP6 dephosphorylates DNA-PKcs at Ser3205 in mitosis and after IR (ionizing radiation). DNA-PKcs also phosphorylates Chk2 on Thr68 in mitosis and both phosphorylation of Chk2 and autophosphorylation of DNA-PKcs in mitosis occur in the apparent absence of Ku and DNA damage. Our findings provide mechanistic insight into the roles of DNA-PKcs and PP6 in mitosis and suggest that DNA-PKcs' role in mitosis may be mechanistically distinct from its well-established role in NHEJ.

Synthesis and SAR studies of novel 2-(6-aminomethylaryl-2-aryl-4-oxo-quinazolin-3(4H)-yl)acetamide vasopressin V1b receptor antagonists.

Science.gov (United States)

Napier, Susan E; Letourneau, Jeffrey J; Ansari, Nasrin; Auld, Douglas S; Baker, James; Best, Stuart; Campbell-Wan, Leigh; Chan, Ray; Craighead, Mark; Desai, Hema; Ho, Koc-Kan; MacSweeney, Cliona; Milne, Rachel; Richard Morphy, J; Neagu, Irina; Ohlmeyer, Michael H J; Pick, Jack; Presland, Jeremy; Riviello, Chris; Zanetakos, Heather A; Zhao, Jiuqiao; Webb, Maria L

2011-06-15

Synthesis and structure-activity relationships (SAR) of a novel series of vasopressin V(1b) antagonists are described. 2-(6-Aminomethylaryl-2-aryl-4-oxo-quinazolin-3(4H)-yl)acetamide have been identified with low nanomolar affinity for the V(1b) receptor and good selectivity with respect to related receptors V(1a), V(2) and OT. Optimised compound 16 shows a good pharmacokinetic profile and activity in a mechanistic model of HPA dysfunction. Copyright © 2011 Elsevier Ltd. All rights reserved.

Effects of tyrosine kinase and phosphatase inhibitors on mitosis progression in synchronized tobacco BY-2 cells.

Science.gov (United States)

Sheremet, Ya A; Yemets, A I; Azmi, A; Vissenberg, K; Verbelen, J P; Blume, Ya B

2012-01-01

To test whether reversible tubulin phosphorylation plays any role in the process of plant mitosis the effects of inhibitors of tyrosine kinases, herbimycin A, genistein and tyrphostin AG 18, and of an inhibitor of tyrosine phosphatases, sodium orthovanadate, on microtubule organization and mitosis progression in a synchronized BY-2 culture has been investigated. It was found that treatment with inhibitors of tyrosine kinases of BY-2 cells at the G2/M transition did not lead to visible disturbances of mitotic microtubule structures, while it did reduce the frequency of their appearance. We assume that a decreased tyrosine phosphorylation level could alter the microtubule dynamic instability parameters during interphase/prophase transition. All types of tyrosine kinase inhibitors used caused a prophase delay: herbimycin A and genistein for 2 h, and tyrphostin AG18 for 1 h. Thereafter the peak of mitosis was displaced for 1 h by herbimycin A or genistein exposure, but after tyrphostin AG18 treatment the timing of the mitosis-peak was comparable to that in control cells. Enhancement of tyrosine phosphorylation induced by the tyrosine phosphatase inhibitor resulted in the opposite effect on BY-2 mitosis transition. Culture treatment with sodium orthovanadate during 1 h resulted in an accelerated start of the prophase and did not lead to the alteration in time of the mitotic index peak formation, as compared to control cells. We suppose that the reversible tyrosine phosphorylation can be involved in the regulation of interphase to M phase transition possibly through regulation of microtubule dynamics in plant cells.

TMBP200, a XMAP215 homologue of tobacco BY-2 cells, has an essential role in plant mitosis.

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Yasuhara, Hiroki; Oe, Yuki

2011-07-01

TMBP200 from tobacco BY-2 cells is a member of the highly conserved family of microtubule-associated proteins that includes Xenopus XMAP215, human TOGp, and Arabidopsis MOR1/GEM1. XMAP215 homologues have an essential role in spindle assembly and function in animals and yeast, but their role in plant mitosis is not fully clarified. Here, we show by immunoblot analysis that TMBP200 levels in synchronously cultured BY-2 cells increased when the cells entered mitosis, thus indicating that TMBP200 plays an important role in mitosis in tobacco. To investigate the role of TMBP200 in mitosis, we employed inducible RNA interference to silence TMBP200 expression in BY-2 cells. The resulting depletion of TMBP200 caused severe defects in bipolar spindle formation and resulted in the appearance of multinucleated cells with variable-sized nuclei. This finding indicates that TMBP200 has an essential role in bipolar spindle formation and function.

Transcriptional intermediary factor 1γ binds to the anaphase-promoting complex/cyclosome and promotes mitosis

DEFF Research Database (Denmark)

Sedgwick, G.G.; Townsend, K.; Martin, A.

2013-01-01

The anaphase-promoting complex/cyclosome (APC/C) is an ubiquitin ligase that functions during mitosis. Here we identify the transcriptional regulator, transcriptional intermediary factor 1γ, TIF1γ, as an APC/C-interacting protein that regulates APC/C function. TIF1γ is not a substrate for APC....../C-dependent ubiquitylation but instead, associates specifically with the APC/C holoenzyme and Cdc20 to affect APC/C activity and progression through mitosis. RNA interference studies indicate that TIF1γ knockdown results in a specific reduction in APC/C ubiquitin ligase activity, the stabilization of APC/C substrates......, and an increase in the time taken for cells to progress through mitosis from nuclear envelope breakdown to anaphase. TIF1γ knockdown cells are also characterized by the inappropriate presence of cyclin A at metaphase, and an increase in the number of cells that fail to undergo metaphase-to-anaphase transition...

Double-strand break repair-adox: Restoration of suppressed double-strand break repair during mitosis induces genomic instability.

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Terasawa, Masahiro; Shinohara, Akira; Shinohara, Miki

2014-12-01

Double-strand breaks (DSBs) are one of the severest types of DNA damage. Unrepaired DSBs easily induce cell death and chromosome aberrations. To maintain genomic stability, cells have checkpoint and DSB repair systems to respond to DNA damage throughout most of the cell cycle. The failure of this process often results in apoptosis or genomic instability, such as aneuploidy, deletion, or translocation. Therefore, DSB repair is essential for maintenance of genomic stability. During mitosis, however, cells seem to suppress the DNA damage response and proceed to the next G1 phase, even if there are unrepaired DSBs. The biological significance of this suppression is not known. In this review, we summarize recent studies of mitotic DSB repair and discuss the mechanisms of suppression of DSB repair during mitosis. DSB repair, which maintains genomic integrity in other phases of the cell cycle, is rather toxic to cells during mitosis, often resulting in chromosome missegregation and aberration. Cells have multiple safeguards to prevent genomic instability during mitosis: inhibition of 53BP1 or BRCA1 localization to DSB sites, which is important to promote non-homologous end joining or homologous recombination, respectively, and also modulation of the non-homologous end joining core complex to inhibit DSB repair. We discuss how DSBs during mitosis are toxic and the multiple safeguard systems that suppress genomic instability. © 2014 The Authors. Cancer Science published by Wiley Publishing Asia Pty Ltd on behalf of Japanese Cancer Association.

Specific primary sequence requirements for Aurora B kinase-mediated phosphorylation and subcellular localization of TMAP during mitosis.

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Kim, Hyun-Jun; Kwon, Hye-Rim; Bae, Chang-Dae; Park, Joobae; Hong, Kyung U

2010-05-15

During mitosis, regulation of protein structures and functions by phosphorylation plays critical roles in orchestrating a series of complex events essential for the cell division process. Tumor-associated microtubule-associated protein (TMAP), also known as cytoskeleton-associated protein 2 (CKAP2), is a novel player in spindle assembly and chromosome segregation. We have previously reported that TMAP is phosphorylated at multiple residues specifically during mitosis. However, the mechanisms and functional importance of phosphorylation at most of the sites identified are currently unknown. Here, we report that TMAP is a novel substrate of the Aurora B kinase. Ser627 of TMAP was specifically phosphorylated by Aurora B both in vitro and in vivo. Ser627 and neighboring conserved residues were strictly required for efficient phosphorylation of TMAP by Aurora B, as even minor amino acid substitutions of the phosphorylation motif significantly diminished the efficiency of the substrate phosphorylation. Nearly all mutations at the phosphorylation motif had dramatic effects on the subcellular localization of TMAP. Instead of being localized to the chromosome region during late mitosis, the mutants remained associated with microtubules and centrosomes throughout mitosis. However, the changes in the subcellular localization of these mutants could not be completely explained by the phosphorylation status on Ser627. Our findings suggest that the motif surrounding Ser627 ((625) RRSRRL (630)) is a critical part of a functionally important sequence motif which not only governs the kinase-substrate recognition, but also regulates the subcellular localization of TMAP during mitosis.

Chromosome Bridges Maintain Kinetochore-Microtubule Attachment throughout Mitosis and Rarely Break during Anaphase.

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Pampalona, Judit; Roscioli, Emanuele; Silkworth, William T; Bowden, Brent; Genescà, Anna; Tusell, Laura; Cimini, Daniela

2016-01-01

Accurate chromosome segregation during cell division is essential to maintain genome stability, and chromosome segregation errors are causally linked to genetic disorders and cancer. An anaphase chromosome bridge is a particular chromosome segregation error observed in cells that enter mitosis with fused chromosomes/sister chromatids. The widely accepted Breakage/Fusion/Bridge cycle model proposes that anaphase chromosome bridges break during mitosis to generate chromosome ends that will fuse during the following cell cycle, thus forming new bridges that will break, and so on. However, various studies have also shown a link between chromosome bridges and aneuploidy and/or polyploidy. In this study, we investigated the behavior and properties of chromosome bridges during mitosis, with the idea to gain insight into the potential mechanism underlying chromosome bridge-induced aneuploidy. We find that only a small number of chromosome bridges break during anaphase, whereas the rest persist through mitosis into the subsequent cell cycle. We also find that the microtubule bundles (k-fibers) bound to bridge kinetochores are not prone to breakage/detachment, thus supporting the conclusion that k-fiber detachment is not the cause of chromosome bridge-induced aneuploidy. Instead, our data suggest that while the microtubules bound to the kinetochores of normally segregating chromosomes shorten substantially during anaphase, the k-fibers bound to bridge kinetochores shorten only slightly, and may even lengthen, during anaphase. This causes some of the bridge kinetochores/chromosomes to lag behind in a position that is proximal to the cell/spindle equator and may cause the bridged chromosomes to be segregated into the same daughter nucleus or to form a micronucleus.

Anther-preferential expressing gene PMR is essential for the mitosis of pollen development in rice.

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Liu, Yaqin; Xu, Ya; Ling, Sheng; Liu, Shasha; Yao, Jialing

2017-06-01

Phenotype identification, expression examination, and function prediction declared that the anther-preferential expressing gene PMR may participate in regulation of male gametophyte development in rice. Male germline development in flowering plants produces the pair of sperm cells for double fertilization and the pollen mitosis is a key process of it. Although the structural features of male gametophyte have been defined, the molecular mechanisms regulating the mitotic cell cycle are not well elucidated in rice. Here, we reported an anther-preferential expressing gene in rice, PMR (Pollen Mitosis Relative), playing an essential role in male gametogenesis. When PMR gene was suppressed via RNAi, the mitosis of microspore was severely damaged, and the plants formed unmatured pollens containing only one or two nucleuses at the anthesis, ultimately leading to serious reduction of pollen fertility and seed-setting. The CRISPR mutants, pmr-1 and pmr-2, both showed the similar defects as the PMR-RNAi lines. Further analysis revealed that PMR together with its co-expressing genes were liable to participate in the regulation of DNA metabolism in the nucleus, and affected the activities of some enzymes related to the cell cycle. We finally discussed that unknown protein PMR contained the PHD, SWIB and Plus-3 domains and they might have coordinating functions in regulation pathway of the pollen mitosis in rice.

Phosphorylation by CK2 regulates MUS81/EME1 in mitosis and after replication stress.

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Palma, Anita; Pugliese, Giusj Monia; Murfuni, Ivana; Marabitti, Veronica; Malacaria, Eva; Rinalducci, Sara; Minoprio, Anna; Sanchez, Massimo; Mazzei, Filomena; Zolla, Lello; Franchitto, Annapaola; Pichierri, Pietro

2018-06-01

The MUS81 complex is crucial for preserving genome stability through the resolution of branched DNA intermediates in mitosis. However, untimely activation of the MUS81 complex in S-phase is dangerous. Little is known about the regulation of the human MUS81 complex and how deregulated activation affects chromosome integrity. Here, we show that the CK2 kinase phosphorylates MUS81 at Serine 87 in late-G2/mitosis, and upon mild replication stress. Phosphorylated MUS81 interacts with SLX4, and this association promotes the function of the MUS81 complex. In line with a role in mitosis, phosphorylation at Serine 87 is suppressed in S-phase and is mainly detected in the MUS81 molecules associated with EME1. Loss of CK2-dependent MUS81 phosphorylation contributes modestly to chromosome integrity, however, expression of the phosphomimic form induces DSBs accumulation in S-phase, because of unscheduled targeting of HJ-like DNA intermediates, and generates a wide chromosome instability phenotype. Collectively, our findings describe a novel regulatory mechanism controlling the MUS81 complex function in human cells. Furthermore, they indicate that, genome stability depends mainly on the ability of cells to counteract targeting of branched intermediates by the MUS81/EME1 complex in S-phase, rather than on a correct MUS81 function in mitosis.

Use of unstable chromosome aberrations for biological dosimetry after the first postirradiation mitosis

International Nuclear Information System (INIS)

Doloy, M.T.; Malarbet, J.L.; Guedeney, G.; Bourguignon, M.; Leroy, A.; Reillaudou, M.; Masse, R.

1991-01-01

The loss of unstable chromosome aberrations after the first postirradiation mitosis makes their use difficult in radiation dosimetry. We describe here a method which, in a cell population observed at this stage, allows retrospective estimation of the frequencies of the unstable aberrations induced at the time of irradiation, and their use as a dosimeter. The laws controlling the behavior of unstable aberrations during mitosis were defined from a large-scale experiment on irradiated human lymphocytes. For cells undergoing the first, second, or third mitosis after irradiation, relationships were determined between the frequency, at irradiation time, of acentric fragments not arising from formation of dicentrics or rings, and the ratio of dicentrics and centric rings appearing without acentric fragments to the total number of dicentrics plus rings. On the basis of this ratio, the method described here provides an assessment of the postirradiation mitotic activity in a cell population. This assessment permitted estimation of the cell distribution and frequency of dicentrics plus centric rings, and of the frequency of acentric fragments at the time of irradiation. The use of this method for retrospective dosimetry after whole-body irradiation under various conditions of exposure is illustrated

[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.

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.

Characteristics of the Emotional and Behavioral Reactions of Rats under Chronic Stress Immobilization During Treatment with 5-R-thio-tetrazol [1,5-c] quinazoline Derivatives

Directory of Open Access Journals (Sweden)

О. Y. Tozyuk

2013-10-01

Full Text Available Hypokinesia can reduce physical performance and impair human health, which is evident by significant morphofunctional changes in the body. To correct these abnormalities and prevent their occurrence actoprotectors are used in hospitals. In previous studies [Stepanyuk G.I, 2012] we found that 5-R-thio-tetrazol [1,5-c] quinasoline derivatives quite clearly improved physical performance of rats according to swimming test. In terms of actoprotective activity compound-leader КВ-28 (sodium 2-( tetrazol [1,5-с] quinazolin -5- ylthioacetate for certain predominated over reference compound bemityl. WORK OBJECTIVE. To describe the influence of course administration of sodium 2-( tetrazol [1,5-с] quinazolin -5- ylthio acetate in comparison with bemityl on the behavioral reactions of rats under 18-day hypokinesia. RESEARCH MATERIALS AND METHODS. Chronic stress immobilization was modeled by keeping rats in small wooden cases for 16 hours / day for 18 days. Animals were divided into 4 groups of 6 animals in each: I - intact animals, II - rats stressed with hypokinesia without correction (control, III and IV - hypokinetic rats who one-time within 18 days take daily intraperitoneally КВ -28 (1,7 mg/kg and bemityl (32 mg/kg at doses equal to their ED50 according to swimming test. Orientative-searching and emotional activity were assessed by neuroethological "open field" test [Buresh, 1991] on the 4th, 12th and 18th day of experiment, that accordingly characterize the stage of anxiety, resistance and exhaustion of general adaptation syndrome [Stefanov, 2001]. To analyze the behavior the following neurophysiological indices were used: horizontal motor activity (number of the crossed squares, vertical activity (number of racks, number of examined holes and autonomic balance: number of washings (grooming and defecation acts (number of boluses and urinations. Duration of observation was 3 min. RESULTS AND THEIR DISCUSSION. In the course of the experiment a

Remodeling of bovine oviductal epithelium by mitosis of secretory cells.

Science.gov (United States)

Ito, Sayaka; Kobayashi, Yoshihiko; Yamamoto, Yuki; Kimura, Koji; Okuda, Kiyoshi

2016-11-01

Two types of oviductal epithelial cells, secretory and ciliated, play crucial roles in the first days after fertilization in mammals. Secretory cells produce various molecules promoting embryo development, while ciliated cells facilitate transport of oocytes and zygotes by ciliary beating. The proportions of the two cell types change during the estrous cycle. The proportion of ciliated cells on the oviductal luminal surface is abundant at the follicular phase, whereas the proportion of secretory cells gradually increases with the formation of the corpus luteum. In the present study, we hypothesize that the proportions of ciliated and secretory epithelial cells are regulated by mitosis. The proportion of the cells being positive for FOXJ1 (a ciliated cell marker) or Ki67 (a mitosis marker) in epithelial cells during the estrous cycle were immunohistochemically examined. Ki67 and FOXJ1 or PAX8 (a secretory cell marker), were double-stained to clarify which types of epithelial cells undergo mitosis. In the ampulla, the percentage of FOXJ1-positive cells was highest at the day of ovulation (Day 0) and decreased by about 50 % by Days 8-12, while in the isthmus it did not change during the estrous cycle. The proportion of Ki67-positive cells was highest at around the time of ovulation in both the ampulla and isthmus. All the Ki67-positive cells were PAX8-positive and FOXJ1-negative in both the ampulla and isthmus. These findings suggest that epithelial remodeling, which is regulated by differentiation and/or proliferation of secretory cells of the oviduct, provides the optimal environment for gamete transport, fertilization and embryonic development.

2-(2-Oxo-1,4-dihydro-2H-quinazolin-3-yl)- and 2-(2,2-dioxo-1,4-dihydro-2H-2lambda6-benzo[1,2,6]thiadiazin-3-yl)-N-hydroxy-acetamides as potent and selective peptide deformylase inhibitors.

Science.gov (United States)

Apfel, C; Banner, D W; Bur, D; Dietz, M; Hubschwerlen, C; Locher, H; Marlin, F; Masciadri, R; Pirson, W; Stalder, H

2001-06-07

Potent, selective, and structurally new inhibitors of the Fe(II) enzyme Escherichia coli peptide deformylase (PDF) were obtained by rational optimization of the weakly binding screening hit (5-chloro-2-oxo-1,4-dihydro-2H-quinazolin-3-yl)-acetic acid hydrazide (1). Three-dimensional structural information, gathered from Ni-PDF complexed with 1, suggested the preparation of two series of related hydroxamic acid analogues, 2-(2-oxo-1,4-dihydro-2H-quinazolin-3-yl)-N-hydroxy-acetamides (A) and 2-(2,2-dioxo-1,4-dihydro-2H-2lambda(6)-benzo[1,2,6]thiadiazin-3-yl)-N-hydroxy-acetamides (B), among which potent PDF inhibitors (37, 42, and 48) were identified. Moreover, two selected compounds, one from each series, 36 and 41, showed good selectivity for PDF over several endoproteases including matrix metalloproteases. However, these compounds showed only weak antibacterial activity.

TopBP1 is required at mitosis to reduce transmission of DNA damage to G1 daughter cells

DEFF Research Database (Denmark)

Pedersen, Rune Troelsgaard; Kruse, Thomas; Nilsson, Jakob

2015-01-01

mitotic entry. In early mitosis, TopBP1 marks sites of and promotes unscheduled DNA synthesis. Moreover, TopBP1 is required for focus formation of the structure-selective nuclease and scaffold protein SLX4 in mitosis. Persistent TopBP1 foci transition into 53BP1 nuclear bodies (NBs) in G1 and precise...... temporal depletion of TopBP1 just before mitotic entry induced formation of 53BP1 NBs in the next cell cycle, showing that TopBP1 acts to reduce transmission of DNA damage to G1 daughter cells. Based on these results, we propose that TopBP1 maintains genome integrity in mitosis by controlling chromatin...

Requirements of cyclin a for mitosis are independent of its subcellular localization.

Science.gov (United States)

Dienemann, Axel; Sprenger, Frank

2004-06-22

Cyclin A (CycA), the only essential mitotic cyclin in Drosophila, is cytoplasmic during interphase and accumulates in the nucleus during prophase. We show that interphase localization is mediated by Leptomycin B (LMB)-sensitive nuclear export. This is a feature shared with human CyclinB1, and it is assumed that nuclear accumulation is necessary for mitotic entry. Here, we tested if the unique mitotic function of CycA requires nuclear accumulation. We fused subcellular localization signals to CycA and tested their mitotic capability. Surprisingly, nuclear accumulation was not required, and even a membrane-tethered form of CycA was able to induce mitosis. We noted that Cyclin B (CycB) protein disappears prematurely in CycA mutants, reminiscent of rca1 mutants. Rca1 is an inhibitor of Fizzy-related-APC/C activity, and in rca1 mutants, mitotic cyclins are degraded in G2 of the 16(th) embryonic cell cycle. Overexpression of Rca1 can restore mitosis in CycA mutants, indicating that the mitotic failure of CycA mutants is caused by premature activation of the APC/C. The essential mitotic function of CycA is therefore not the activation of numerous mitotic substrates by Cdk1-dependent phosphorylation. Rather, CycA-dependent kinase activity is required to inhibit one inhibitor of mitosis, the Fzr protein.

Possible mechanisms of chromosomal aberrations: VII. Comparative dynamics of sister chromatid disjunction and realization of radiation-induced chromosomal aberrations during mitosis

International Nuclear Information System (INIS)

Lebedeva, L.I.; Akhmamet'eva, E.M.

1994-01-01

An increase in radiation-induced chromosomal aberrations during c-metaphase sister chromatid disjunction was demonstrated in murine bone marrow cells exposed to a total γ-irradiation at 0.5 Gy. Caffeine (Cf) treatment during mitosis partially suppressed the chromatid disjunction rate and increased the number of radiation-induced aberrations in this mitosis. Nalidixic acid (NA) treatment of c-metaphase cells completely suppressed chromatid disjunction and the realization of induced aberrations. Topoisomerase 2 was assumed to be involved during mitosis in both processes

Novel functions for the endocytic regulatory proteins MICAL-L1 and EHD1 in mitosis.

Science.gov (United States)

Reinecke, James B; Katafiasz, Dawn; Naslavsky, Naava; Caplan, Steve

2015-01-01

During interphase, recycling endosomes mediate the transport of internalized cargo back to the plasma membrane. However, in mitotic cells, recycling endosomes are essential for the completion of cytokinesis, the last phase of mitosis that promotes the physical separation the two daughter cells. Despite recent advances, our understanding of the molecular determinants that regulate recycling endosome dynamics during cytokinesis remains incomplete. We have previously demonstrated that Molecule Interacting with CasL Like-1 (MICAL-L1) and C-terminal Eps15 Homology Domain protein 1 (EHD1) coordinately regulate receptor transport from tubular recycling endosomes during interphase. However, their potential roles in controlling cytokinesis had not been addressed. In this study, we show that MICAL-L1 and EHD1 regulate mitosis. Depletion of either protein resulted in increased numbers of bi-nucleated cells. We provide evidence that bi-nucleation in MICAL-L1- and EHD1-depleted cells is a consequence of impaired recycling endosome transport during late cytokinesis. However, depletion of MICAL-L1, but not EHD1, resulted in aberrant chromosome alignment and lagging chromosomes, suggesting an EHD1-independent function for MICAL-L1 earlier in mitosis. Moreover, we provide evidence that MICAL-L1 and EHD1 differentially influence microtubule dynamics during early and late mitosis. Collectively, our new data suggest several unanticipated roles for MICAL-L1 and EHD1 during the cell cycle. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Synthesis, characterization, and anticancer activity of new quinazoline derivatives against MCF-7 cells.

Science.gov (United States)

Faraj, Fadhil Lafta; Zahedifard, Maryam; Paydar, Mohammadjavad; Looi, Chung Yeng; Abdul Majid, Nazia; Ali, Hapipah Mohd; Ahmad, Noraini; Gwaram, Nura Suleiman; Abdulla, Mahmood Ameen

2014-01-01

Two new synthesized and characterized quinazoline Schiff bases 1 and 2 were investigated for anticancer activity against MCF-7 human breast cancer cell line. Compounds 1 and 2 demonstrated a remarkable antiproliferative effect, with an IC50 value of 6.246×10(-6) mol/L and 5.910×10(-6) mol/L, respectively, after 72 hours of treatment. Most apoptosis morphological features in treated MCF-7 cells were observed by AO/PI staining. The results of cell cycle analysis indicate that compounds did not induce S and M phase arrest in cell after 24 hours of treatment. Furthermore, MCF-7 cells treated with 1 and 2 subjected to apoptosis death, as exhibited by perturbation of mitochondrial membrane potential and cytochrome c release as well as increase in ROS formation. We also found activation of caspases-3/7, -8, and -9 in compounds 1 and 2. Moreover, inhibition of NF-κB translocation in MCF-7 cells treated by compound 1 significantly exhibited the association of extrinsic apoptosis pathway. Acute toxicity results demonstrated the nontoxic nature of the compounds in mice. Our results showed significant activity towards MCF-7 cells via either intrinsic or extrinsic mitochondrial pathway and are potential candidate for further in vivo and clinical breast cancer studies.

Experimental study of mutagenous and mitosis modifying activity of silver nanoparticles

Directory of Open Access Journals (Sweden)

B. S. Kirbik

2015-01-01

Full Text Available Mutagenous and mitosis modifying impact of silver nanoparticles has been studied on outbred mice. Nanoparticles were of round shape with dimensions of 5-50 nm, size of generated organic shell of 2-5 nm, the quantity in 1 mcm3 makes 120-270. Metaphasic analysis of mice bone marrow cells was used as a testing technique. The frequency of chromosome aberrations and mitotic index of preparations were accounted. During single intraperitoneal administration of the agent in the dose of 250 mcg/kg the silver nanoparticles demonstrated mitosis stimulating activity. No mutagenous effect of silver nanoparticles by daily administration for 4 days of 25 mcg/kg and single administration in the dose of 250 mcg/kg has been registered, but there is statistically insignificant tendency of aberrant metaphases increase. Consequently silver nanoparticles in the investigated doses demonstrated no mutagenous activity and can be considered safe for mammalian cells.

Kindlin1 regulates microtubule function to ensure normal mitosis.

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Patel, Hitesh; Stavrou, Ifigeneia; Shrestha, Roshan L; Draviam, Viji; Frame, Margaret C; Brunton, Valerie G

2016-08-01

Loss of Kindlin 1 (Kin1) results in the skin blistering disorder Kindler Syndrome (KS), whose symptoms also include skin atrophy and reduced keratinocyte proliferation. Kin1 binds to integrins to modulate their activation and more recently it has been shown to regulate mitotic spindles and cell survival in a Plk1-dependent manner. Here we report that short-term Kin1 deletion in mouse skin results in impaired mitosis, which is associated with reduced acetylated tubulin (ac-tub) levels and cell proliferation. In cells, impaired mitosis and reduced ac-tub levels are also accompanied by reduced microtubule stability, all of which are rescued by HDAC6 inhibition. The ability of Kin1 to regulate HDAC6-dependent cellular ac-tub levels is dependent on its phosphorylation by Plk1. Taken together, these data define a novel role for Kin1 in microtubule acetylation and stability and offer a mechanistic insight into how certain KS phenotypes, such as skin atrophy and reduced cell proliferation, arise. © The Author (2016). Published by Oxford University Press on behalf of Journal of Molecular Cell Biology, IBCB, SIBS, CAS.

Human geminin promotes pre-RC formation and DNA replication by stabilizing CDT1 in mitosis

DEFF Research Database (Denmark)

Ballabeni, Andrea; Melixetian, Marina; Zamponi, Raffaella

2004-01-01

-mediated degradation by inhibiting its ubiquitination. In particular, Geminin ensures basal levels of CDT1 during S phase and its accumulation during mitosis. Consistently, inhibition of Geminin synthesis during M phase leads to impairment of pre-RC formation and DNA replication during the following cell cycle....... Moreover, we show that inhibition of CDK1 during mitosis, and not Geminin depletion, is sufficient for premature formation of pre-RCs, indicating that CDK activity is the major mitotic inhibitor of licensing in human cells. Taken together with recent data from our laboratory, our results demonstrate...

The roles of cohesins in mitosis, meiosis, and human health and disease

Science.gov (United States)

Brooker, Amanda S.; Berkowitz, Karen M.

2015-01-01

Summary Mitosis and meiosis are essential processes that occur during development. Throughout these processes, cohesion is required to keep the sister chromatids together until their separation at anaphase. Cohesion is created by multi-protein subunit complexes called cohesins. Although the subunits differ slightly in mitosis and meiosis, the canonical cohesin complex is composed of four subunits that are quite diverse. The cohesin complexes are also important for DNA repair, gene expression, development, and genome integrity. Here we provide an overview of the roles of cohesins during these different events, as well as their roles in human health and disease, including the cohesinopathies. Although the exact roles and mechanisms of these proteins are still being elucidated, this review will serve as a guide for the current knowledge of cohesins. PMID:24906316

Centrosomes split in the presence of impaired DNA integrity during mitosis

NARCIS (Netherlands)

Hut, HMJ; Lemstra, W; Blaauw, EH; van Cappellen, GWA; Kampinga, HH; Sibon, OCM

A well-established function of centrosomes is their role in accomplishing a successful mitosis that gives rise to a pair of identical daughter cells. We recently showed that DNA replication defects and DNA damage in Drosophila embryos trigger centrosomal changes, but it remained unclear whether

Assessment of algorithms for mitosis detection in breast cancer histopathology images

NARCIS (Netherlands)

Veta, M.; Diest, van P.J.; Willems, S.M.; Wang, Haibo; Madabhushi, A. (Anant); Cruz-Roa, A. (Angel); González, F.; Larsen, A.B.L. (Anders); Vestergaard, J.S. (Jacob); Dahl, A.B. (Anders); Ciresan, D.C. (Dan); Schmidhuber, J.; Giusti, A. (Alessandro); Gambardella, L.M. (Luca); Tek, F. Boray; Walter, Th. (Thomas); Wang, Ching-Wei; Kondo, Satoshi; Matuszewski, B.J. (Bogdan); Precioso, F. (Frederic); Snell, V. (Violet); Kittler, Josef; de Campos, Teofilo E.; Khan, Adnan M.; Rajpoot, Nasir M.; Arkoumani, Evdokia; Lacle, Miangela M.; Viergever, M.A.; Pluim, J.P.W.

2015-01-01

The proliferative activity of breast tumors, which is routinely estimated by counting of mitotic figures in hematoxylin and eosin stained histology sections, is considered to be one of the most important prognostic markers. However, mitosis counting is laborious, subjective and may suffer from low

Assessment of algorithms for mitosis detection in breast cancer histopathology images

DEFF Research Database (Denmark)

Veta, Mitko; van Diest, Paul J.; Willems, Stefan M.

2014-01-01

The proliferative activity of breast tumors, which is routinely estimated by counting of mitotic figures in hematoxylin and eosin stained histology sections, is considered to be one of the most important prognostic markers. However, mitosis counting is laborious, subjective and may suffer from lo...

Role of substrate concentration in mitosis and hyphal extension of Aspergillus

DEFF Research Database (Denmark)

Müller, Christian; Spohr, Anders Bendsen; Nielsen, Jens

2000-01-01

The filamentous fungi Aspergillus oryzae and A. niger grow by apical extension of multinucleate hyphae that are subdivided into compartments by cross-walls called septa. Submerged cultivation, image analysis, and fluorescence microscopy were used to study the role of the carbon source on mitosis...

Clathrin is spindle-associated but not essential for mitosis.

Directory of Open Access Journals (Sweden)

Joana Borlido

Full Text Available Clathrin is a multimeric protein involved in vesicle coat assembly. Recently clathrin distribution was reported to change during the cell cycle and was found to associate with the mitotic spindle. Here we test whether the recruitment of clathrin to the spindle is indicative of a critical functional contribution to mitosis.Previously a chicken pre-B lymphoma cell line (DKO-R was developed in which the endogenous clathrin heavy chain alleles were replaced with the human clathrin heavy chain under the control of a tetracycline-regulatable promoter. Receptor-mediated and fluid-phase endocytosis were significantly inhibited in this line following clathrin knockout, and we used this to explore the significance of clathrin heavy chain expression for cell cycle progression. We confirmed using confocal microscopy that clathrin colocalised with tubulin at mitotic spindles. Using a propidium iodide flow cytometric assay we found no statistical difference in the cell cycle distribution of the knockout cells versus the wild-type. Additionally, we showed that the ploidy and the recovery kinetics following cell cycle arrest with nocodazole were unchanged by repressing clathrin heavy chain expression.We conclude that the association of clathrin with the mitotic spindle and the contribution of clathrin to endocytosis are evolutionarily conserved. However we find that the contribution of clathrin to mitosis is less robust and dependent on cellular context. In other cell-lines silencing RNA has been used by others to knockdown clathrin expression resulting in an increase in the mitotic index of the cells. We show an effect on the G2/M phase population of clathrin knockdown in HEK293 cells but show that repressing clathrin expression in the DKO-R cell-line has no effect on the size of this population. Consequently this work highlights the need for a more detailed molecular understanding of the recruitment and function of clathrin at the spindle, since the

INPP5E Preserves Genomic Stability through Regulation of Mitosis.

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Sierra Potchanant, Elizabeth A; Cerabona, Donna; Sater, Zahi Abdul; He, Ying; Sun, Zejin; Gehlhausen, Jeff; Nalepa, Grzegorz

2017-03-15

The partially understood phosphoinositide signaling cascade regulates multiple aspects of cellular metabolism. Previous studies revealed that INPP5E, the inositol polyphosphate-5-phosphatase that is mutated in the developmental disorders Joubert and MORM syndromes, is essential for the function of the primary cilium and maintenance of phosphoinositide balance in nondividing cells. Here, we report that INPP5E further contributes to cellular homeostasis by regulating cell division. We found that silencing or genetic knockout of INPP5E in human and murine cells impairs the spindle assembly checkpoint, centrosome and spindle function, and maintenance of chromosomal integrity. Consistent with a cell cycle regulatory role, we found that INPP5E expression is cell cycle dependent, peaking at mitotic entry. INPP5E localizes to centrosomes, chromosomes, and kinetochores in early mitosis and shuttles to the midzone spindle at mitotic exit. Our findings identify the previously unknown, essential role of INPP5E in mitosis and prevention of aneuploidy, providing a new perspective on the function of this phosphoinositide phosphatase in health and development. Copyright © 2017 Sierra Potchanant et al.

Dysregulation of the mitosis-meiosis switch in testicular carcinoma in situ

DEFF Research Database (Denmark)

Jørgensen, Anne; Nielsen, John E; Almstrup, Kristian

2013-01-01

, except in spermatocytic seminoma (not derived from CIS). In conclusion, this study indicates that meiosis signalling is dysregulated in CIS cells and that a key regulator of the mitosis-meiosis switch, DMRT1, is expressed in 'early-stage' CIS cells but is down-regulated with further invasive...

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

Science.gov (United States)

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.

Meeting report--Getting Into and Out of Mitosis.

Science.gov (United States)

Mchedlishvili, Nunu; Jonak, Katarzyna; Saurin, Adrian T

2015-11-15

The Company of Biologists Workshop 'Getting Into and Out of Mitosis' was held 10-13 May 2015 at Wiston House in West Sussex, UK. The workshop brought together researchers from wide-ranging disciplines and provided a forum to discuss their latest work on the control of cell division from mitotic entry to exit. This report highlights the main topics and summarises the discussion around the key themes and questions that emerged from the meeting. © 2015. Published by The Company of Biologists Ltd.

Regularity of mitosis in different varieties of winter bread wheat under the action of herbicides

Directory of Open Access Journals (Sweden)

Tatyana Eugenivna KOPYTCHUK

2012-05-01

Full Text Available The influence of the most widespread herbicides on winter wheat in Ukraine was studied by anaphase test. Treatment with herbicides reduced the germination of the seeds and disturbed the regularity of mitosis in all varieties of wheat. The range of violations of mitosis was demonstrated by the formation of chromosomal aberrations and dysfunctions of cell cytoskeleton which occurred while processing herbicides. Varietal differences between investigated wheat by sensitivity to herbicides were discovered. The most resistant to herbicides was variety Fantasya Odesskaya, and the most sensitive – Nikoniya, while the most harmful herbicide for wheat was Napalm.

Elimination of radiation-induced chromosome damages in human peripheral blood lymphocyte cultures. 2. The frequency of aberrations in the first-fifth post-irradiation mitosis

International Nuclear Information System (INIS)

Pyatkin, E.K.; Pokrovskaya, V.N.; Nugis, V.Yu.

1982-01-01

The number of chromosome aberrations in 1.-5. mitoses cultivated from lymphocyte PHA of peripheric man blood after gamma irradiation in vitro in 1e5; 3 and 6 Gy has been determined. For all the doses, as the cells passed 1. and successive postradiation divisiops, observed was the decrease in the number of aberrant metaphases and all the aberrations of the chromosomal typee at that their elimination rate increases with the dose increase. No considerable differences in the frequency of pair fragments in 1.-4. mitosis after irradiation in 1,5 Gy dose, in 1.-3. mitoses after irradiation in 3 Gy dose and in 1.-2. mitoses after irradiation in 6 Gy dose were found. In lymphocyte cultures irradiated in 3 and 6 Gy doses the number of dicentries in 2. mitosis was approximately 2 times smaller than in 1. mitosis and in 3. mitosis two times smaller than in 2. mitosis. In 1. mitosis almost all the dicentrics have accompanying pair fragments in 2. and 3. mitoses a share of the dicentrics without fragments constituted about 30-70 %, and in 4.-5. mitoses amounted to 95-100 %. The reduction of the number of irregular chromosomes in the process of cell passing of 1. and successive postradiation mitosis was noted only during lymphocyte investigation irradiated in 6 Gy. At 1,5 and 3 Gy doses these aberration frequency in 1.-5. and 1.-4. mitoses were nearly the same

Parkin Regulates Mitosis and Genomic Stability through Cdc20/Cdh1

NARCIS (Netherlands)

Lee, S.B.; Kim, J.J.; Nam, H.J.; Gao, B.; Yin, P.; Qin, B.; Yi, S.Y.; Ham, H.; Evans, D.; Kim, S.H.; Zhang, J.; Deng, M.; Liu, T.; Zhang, H.; Billadeau, D.D.; Wang, L.; Giaime, E.; Shen, J.; Pang, Y.P.; Jen, J.; Deursen, J.M.A. van; Lou, Z.

2015-01-01

Mutations in the E3 ubiquitin ligase Parkin have been linked to familial Parkinson's disease. Parkin has also been implicated in mitosis through mechanisms that are unclear. Here we show that Parkin interacts with anaphase promoting complex/cyclosome (APC/C) coactivators Cdc20 and Cdh1 to mediate

Phospho-Bcl-xL(Ser62) influences spindle assembly and chromosome segregation during mitosis.

Science.gov (United States)

Wang, Jianfang; Beauchemin, Myriam; Bertrand, Richard

2014-01-01

Functional analysis of a series of phosphorylation mutants reveals that Bcl-xL(Ser62Ala) influences cell entry into anaphase and mitotic exit in taxol-exposed cells compared with cells expressing wild-type Bcl-xL or a series of other phosphorylation mutants, an effect that appears to be independent of its anti-apoptotic activity. During normal mitosis progression, Bcl-xL(Ser62) is strongly phosphorylated by PLK1 and MAPK14/SAPKp38α at the prometaphase, metaphase, and the anaphase boundaries, while it is de-phosphorylated at telophase and cytokinesis. Phospho-Bcl-xL(Ser62) localizes in centrosomes with γ-tubulin and in the mitotic cytosol with some spindle-assembly checkpoint signaling components, including PLK1, BubR1, and Mad2. In taxol- and nocodazole-exposed cells, phospho-Bcl-xL(Ser62) also binds to Cdc20- Mad2-, BubR1-, and Bub3-bound complexes, while Bcl-xL(Ser62Ala) does not. Silencing Bcl-xL expression and expressing the phosphorylation mutant Bcl-xL(Ser62Ala) lead to an increased number of cells harboring mitotic spindle defects including multipolar spindle, chromosome lagging and bridging, aneuploidy with micro-, bi-, or multi-nucleated cells, and cells that fail to resolve undergo mitosis within 6 h. Together, the data indicate that during mitosis, Bcl-xL(Ser62) phosphorylation impacts on spindle assembly and chromosome segregation, influencing chromosome stability. Observations of mitotic cells harboring aneuploidy with micro-, bi-, or multi-nucleated cells, and cells that fail to resolve undergo mitosis within 6 h were also made with cells expressing the phosphorylation mutant Bcl-xL(Ser49Ala) and dual mutant Bcl-xL(Ser49/62Ala).

Tau excess impairs mitosis and kinesin-5 function, leading to aneuploidy and cell death.

Science.gov (United States)

Bougé, Anne-Laure; Parmentier, Marie-Laure

2016-03-01

In neurodegenerative diseases such as Alzheimer's disease (AD), cell cycle defects and associated aneuploidy have been described. However, the importance of these defects in the physiopathology of AD and the underlying mechanistic processes are largely unknown, in particular with respect to the microtubule (MT)-binding protein Tau, which is found in excess in the brain and cerebrospinal fluid of affected individuals. Although it has long been known that Tau is phosphorylated during mitosis to generate a lower affinity for MTs, there is, to our knowledge, no indication that an excess of this protein could affect mitosis. Here, we studied the effect of an excess of human Tau (hTau) protein on cell mitosis in vivo. Using the Drosophila developing wing disc epithelium as a model, we show that an excess of hTau induces a mitotic arrest, with the presence of monopolar spindles. This mitotic defect leads to aneuploidy and apoptotic cell death. We studied the mechanism of action of hTau and found that the MT-binding domain of hTau is responsible for these defects. We also demonstrate that the effects of hTau occur via the inhibition of the function of the kinesin Klp61F, the Drosophila homologue of kinesin-5 (also called Eg5 or KIF11). We finally show that this deleterious effect of hTau is also found in other Drosophila cell types (neuroblasts) and tissues (the developing eye disc), as well as in human HeLa cells. By demonstrating that MT-bound Tau inhibits the Eg5 kinesin and cell mitosis, our work provides a new framework to consider the role of Tau in neurodegenerative diseases. © 2016. Published by The Company of Biologists Ltd.

Shape Transformation of the Nuclear Envelope during Closed Mitosis.

Science.gov (United States)

Zhu, Qian; Zheng, Fan; Liu, Allen P; Qian, Jin; Fu, Chuanhai; Lin, Yuan

2016-11-15

The nuclear envelope (NE) in lower eukaryotes such as Schizosaccharomyces pombe undergoes large morphology changes during closed mitosis. However, which physical parameters are important in governing the shape evolution of the NE, and how defects in the dividing chromosomes/microtubules are reflected in those parameters, are fundamental questions that remain unresolved. In this study, we show that improper separation of chromosomes in genetically deficient cells leads to membrane tethering or asymmetric division in contrast to the formation of two equal-sized daughter nuclei in wild-type cells. We hypothesize that the poleward force is transmitted to the nuclear membrane through its physical contact with the separated sister chromatids at the two spindle poles. A theoretical model is developed to predict the morphology evolution of the NE where key factors such as the work done by the poleward force and bending and surface energies stored in the membrane have been taken into account. Interestingly, the predicted phase diagram, summarizing the dependence of nuclear shape on the size of the load transmission regions, and the pole-to-pole distance versus surface area relationship all quantitatively agree well with our experimental observations, suggesting that this model captures the essential physics involved in closed mitosis. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

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)

Elimination of radiation-induced chromosomal damages in numan peripheral blood lymphocyte cultures. 1. The frequency of aberrations in the first and second mitosis

International Nuclear Information System (INIS)

Pyatkin, E.K.; Nugis, V.Yu.

1981-01-01

A comparative analysis of chromosomal aberrations in the first and second mitosis of cultivated human peripheral blood lymphocytes after gamma irradiation in vitro at 1-5 Gy doses has been made. Irradiated blood lymphocytes were incubated for 58 to 66 h at 37 deg with PGA and BDU (20 μg /ml). The first, second and third postradiation mitosises were identified using the distinguishing staining of sister chromatids. The share of the cells in the first mitosis fluctuated from 32 to 77 %, in the second - from 23 to 68 %, and the third - from 0 to 9 %. At all radiation doses significant differences in the frequency of the aberration cells passing the first and second mitosises were revealed as well as in the total number of chromosomal aberrations in all the cells. The frequency of pair fragments and dicentrics chromosomes in the first mitosis was on the average 1.6 and 2 times as high as in the second one, respectively. In the first mitosis almost all dicentric chromosomes occurred with accompanying pair fragments, and in the second mitosis the share of dicentric chromosomes without accompanying fragments was 25 to 50 %. The distribution of the dicentric chromosomes in the cells in the first and second mitosis did not differ from Poison distribution for the 2 to 5 Gy dose range

Cascaded ensemble of convolutional neural networks and handcrafted features for mitosis detection

Science.gov (United States)

Wang, Haibo; Cruz-Roa, Angel; Basavanhally, Ajay; Gilmore, Hannah; Shih, Natalie; Feldman, Mike; Tomaszewski, John; Gonzalez, Fabio; Madabhushi, Anant

2014-03-01

Breast cancer (BCa) grading plays an important role in predicting disease aggressiveness and patient outcome. A key component of BCa grade is mitotic count, which involves quantifying the number of cells in the process of dividing (i.e. undergoing mitosis) at a specific point in time. Currently mitosis counting is done manually by a pathologist looking at multiple high power fields on a glass slide under a microscope, an extremely laborious and time consuming process. The development of computerized systems for automated detection of mitotic nuclei, while highly desirable, is confounded by the highly variable shape and appearance of mitoses. Existing methods use either handcrafted features that capture certain morphological, statistical or textural attributes of mitoses or features learned with convolutional neural networks (CNN). While handcrafted features are inspired by the domain and the particular application, the data-driven CNN models tend to be domain agnostic and attempt to learn additional feature bases that cannot be represented through any of the handcrafted features. On the other hand, CNN is computationally more complex and needs a large number of labeled training instances. Since handcrafted features attempt to model domain pertinent attributes and CNN approaches are largely unsupervised feature generation methods, there is an appeal to attempting to combine these two distinct classes of feature generation strategies to create an integrated set of attributes that can potentially outperform either class of feature extraction strategies individually. In this paper, we present a cascaded approach for mitosis detection that intelligently combines a CNN model and handcrafted features (morphology, color and texture features). By employing a light CNN model, the proposed approach is far less demanding computationally, and the cascaded strategy of combining handcrafted features and CNN-derived features enables the possibility of maximizing performance by

Continuation of mitosis after selective laser microbeam destruction of the centriolar region

Energy Technology Data Exchange (ETDEWEB)

Berns, N.W.; Richardson, S.M.

1977-12-01

The centriole regions of prophase PTK2 cells were irradiated with a laser microbeam. Cells continued through mitosis normally. Ultrastructural analysis revealed either an absence of centrioles or severely damaged centrioles at the irradiated poles. Microtubules appeared to focus into pericentriolar cloud material.

Continuation of mitosis after selective laser microbeam destruction of the centriolar region

International Nuclear Information System (INIS)

Berns, N.W.; Richardson, S.M.

1977-01-01

The centriole regions of prophase PTK2 cells were irradiated with a laser microbeam. Cells continued through mitosis normally. Ultrastructural analysis revealed either an absence of centrioles or severely damaged centrioles at the irradiated poles. Microtubules appeared to focus into pericentriolar cloud material

The G2/M DNA damage checkpoint inhibits mitosis through Tyr15 phosphorylation of p34cdc2 in Aspergillus nidulans.

Science.gov (United States)

Ye, X S; Fincher, R R; Tang, A; Osmani, S A

1997-01-02

It is possible to cause G2 arrest in Aspergillus nidulans by inactivating either p34cdc2 or NIMA. We therefore investigated the negative control of these two mitosis-promoting kinases after DNA damage. DNA damage caused rapid Tyr15 phosphorylation of p34cdc2 and transient cell cycle arrest but had little effect on the activity of NIMA. Dividing cells deficient in Tyr15 phosphorylation of p34cdc2 were sensitive to both MMS and UV irradiation and entered lethal premature mitosis with damaged DNA. However, non-dividing quiescent conidiospores of the Tyr15 mutant strain were not sensitive to DNA damage. The UV and MMS sensitivity of cells unable to tyrosine phosphorylate p34cdc2 is therefore caused by defects in DNA damage checkpoint regulation over mitosis. Both the nimA5 and nimT23 temperature-sensitive mutations cause an arrest in G2 at 42 degrees C. Addition of MMS to nimT23 G2-arrested cells caused a marked delay in their entry into mitosis upon downshift to 32 degrees C and this delay was correlated with a long delay in the dephosphorylation and activation of p34cdc2. Addition of MMS to nimA5 G2-arrested cells caused inactivation of the H1 kinase activity of p34cdc2 due to an increase in its Tyr15 phosphorylation level and delayed entry into mitosis upon return to 32 degrees C. However, if Tyr15 phosphorylation of p34cdc2 was prevented then its H1 kinase activity was not inactivated upon MMS addition to nimA5 G2-arrested cells and they rapidly progressed into a lethal mitosis upon release to 32 degrees C. Thus, Tyr15 phosphorylation of p34cdc2 in G2 arrests initiation of mitosis after DNA damage in A. nidulans.

Novel 2-phenyl-3-{4’-[N-(4”-aminophenylcarbamoyl]-phenyl}-quinazoline-4(3Hone-6-sulphonic acidbased mono azo reactive dyes

Directory of Open Access Journals (Sweden)

DIVYESH R. PATEL

2011-02-01

Full Text Available A series of new heterocyclic mono azo reactive dyes 7a–m were prepared by diazotization of 2-phenyl-3-{4’-[N-(4”-aminophenylcarbamoyl]-phenyl}-quinazoline-4(3H-one-6-sulphonic acid (3 and coupling with various cyanurated coupling components 6a–m and their dyeing performance on silk, wool and cotton fibres was assessed. These dyes were found to give a variety of colour shades with very good depth and levelness on the fibres. All the compounds were identified by conventional method (IR and 1H-NMR and elemental analyses. The percentage dye bath exhaustion on different fibres was reasonably good and acceptable. The dyed fibre showed moderate to very good fastness to light, washing and rubbing.

The Role of Drosophila Merlin in the Control of Mitosis Exit and Development

National Research Council Canada - National Science Library

Chang, Long-Sheng

2007-01-01

To better understand the mechanism by which Merlin functions as a tumor suppressor we have shown that mutations in the Drosophila Merlin gene lead to increased mitosis and alter the duration of the G2...

Planar Cell Polarity Breaks the Symmetry of PAR Protein Distribution prior to Mitosis in Drosophila Sensory Organ Precursor Cells.

Science.gov (United States)

Besson, Charlotte; Bernard, Fred; Corson, Francis; Rouault, Hervé; Reynaud, Elodie; Keder, Alyona; Mazouni, Khalil; Schweisguth, François

2015-04-20

During development, cell-fate diversity can result from the unequal segregation of fate determinants at mitosis. Polarization of the mother cell is essential for asymmetric cell division (ACD). It often involves the formation of a cortical domain containing the PAR complex proteins Par3, Par6, and atypical protein kinase C (aPKC). In the fly notum, sensory organ precursor cells (SOPs) divide asymmetrically within the plane of the epithelium and along the body axis to generate two distinct cells. Fate asymmetry depends on the asymmetric localization of the PAR complex. In the absence of planar cell polarity (PCP), SOPs divide with a random planar orientation but still asymmetrically, showing that PCP is dispensable for PAR asymmetry at mitosis. To study when and how the PAR complex localizes asymmetrically, we have used a quantitative imaging approach to measure the planar polarization of the proteins Bazooka (Baz, fly Par3), Par6, and aPKC in living pupae. By using imaging of functional GFP-tagged proteins with image processing and computational modeling, we find that Baz, Par6, and aPKC become planar polarized prior to mitosis in a manner independent of the AuroraA kinase and that PCP is required for the planar polarization of Baz, Par6, and aPKC during interphase. This indicates that a "mitosis rescue" mechanism establishes asymmetry at mitosis in PCP mutants. This study therefore identifies PCP as the initial symmetry-breaking signal for the planar polarization of PAR proteins in asymmetrically dividing SOPs. Copyright © 2015 Elsevier Ltd. All rights reserved.

Dance of the Chromosomes: A Kinetic Learning Approach to Mitosis and Meiosis

Science.gov (United States)

Kreiser, Brian; Hairston, Rosalina

2007-01-01

Understanding mitosis and meiosis is fundamental to understanding the basics of Mendelian inheritance, yet many students find these concepts challenging or confusing. Here we present a visually and physically stimulating activity using minimal supplies to supplement traditional instruction in order to engage the students and facilitate…

Induction of mitosis in the cultured rabbit lens initiated by the addition of insulin to medium KEI-4

Energy Technology Data Exchange (ETDEWEB)

Reddan, J R; Unakar, N J; Harding, C V; Bagchi, M; Saldana, G

1975-01-01

The epithelium of lenses cultured in KEI-4, a completely defined medium formulated with specific reference to the biochemistry and physiology of the rabbit lens, exhibits a pattern of cell division similar to that noted for the organ in situ. Initial fluctuations in mitotic activity occurred in the area of the germinative zone during the first 24 hr of culture. Mitosis decreased at 1 hr, was extremely low at 3 hr and returned to values comparable for lens in vivo by 22 hr. The precipitous drop in mitosis noted at 3 hr is in part attributable to the isolation of the lens from adjoining tissue. The addition of insulin to KEI-4 triggers a parasynchronous burst of DNA synthesis throughout the central lens epithelium. The activation requires the intact hormone; neither proinsulin nor the A and/or B chains of insulin, nor glucagon nor zinc chloride can initiate mitosis. The gamma-globulin-rich fraction of rabbit serum can also stimulate mitosis. The addition of dibutyryl adenosine 3':5' cyclic monophosphate (DBeAMP) plus theophylline to KEI-4-insulin inhibits mitosis and prevents the cells from entering the synthetic phase of the cell cycle. Theophylline alone or DBeAMP alone brings about a 90 percent reduction in the insulin-induced mitotic responses. Lenses exposed to insulin show a marked increase in RNA synthesis and also exhibit an increased binding of tritiated actinomycin D at 1 and 3 hr of culture relative to KEI-4 controls. The hormone apparently activates the genome including those genes governing cell division. The system is amenable for long-term culture of the mammalian lens and since the constituents of the medium are known it should be possible to determine the factor(s) in the medium which, in conjunction with insulin, are needed for the induction of cell division.

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 importance of G1/S-border and mitosis in the fixation

International Nuclear Information System (INIS)

Iliakis, G.; Nuesse, M.

1983-01-01

The ability of synchronized Ehrlich ascites tumour cells to repair PLD was measured by introducing delays in their progression through the cell cycle either in the same phase as that where the irradiation was given or in a subsequent phase. Cells were incubated for this purpose either in balanced salt solution which nonspecifically delayed progression in all cell cycle phases or with 0.5 μg/ml aphidicolin which delayed cells in S-phase. Cells which had been delayed in their progression through the cell cycle were able to repair PLD irrespective of the phase at which they were held. In cases where the delay in the progression through the cell cycle was introduced in a phase subsequent to that of the exposure to irradiation, repair of PLD was observed only if the cells had not passed the G1/S-border or mitosis. Based on these results, the importance of G1/S-border and mitosis in the fixation of PLD is suggested. (orig.)

Cdk1-cyclin B1-mediated phosphorylation of tumor-associated microtubule-associated protein/cytoskeleton-associated protein 2 in mitosis.

Science.gov (United States)

Hong, Kyung Uk; Kim, Hyun-Jun; Kim, Hyo-Sil; Seong, Yeon-Sun; Hong, Kyeong-Man; Bae, Chang-Dae; Park, Joobae

2009-06-12

During mitosis, establishment of structurally and functionally sound bipolar spindles is necessary for maintaining the fidelity of chromosome segregation. Tumor-associated microtubule-associated protein (TMAP), also known as cytoskeleton-associated protein 2 (CKAP2), is a mitotic spindle-associated protein whose level is frequently up-regulated in various malignancies. Previous reports have suggested that TMAP is a potential regulator of mitotic spindle assembly and dynamics and that it is required for chromosome segregation to occur properly. So far, there have been no reports on how its mitosis-related functions are regulated. Here, we report that TMAP is hyper-phosphorylated at the C terminus specifically during mitosis. At least four different residues (Thr-578, Thr-596, Thr-622, and Ser-627) were responsible for the mitosis-specific phosphorylation of TMAP. Among these, Thr-622 was specifically phosphorylated by Cdk1-cyclin B1 both in vitro and in vivo. Interestingly, compared with the wild type, a phosphorylation-deficient mutant form of TMAP, in which Thr-622 had been replaced with an alanine (T622A), induced a significant increase in the frequency of metaphase cells with abnormal bipolar spindles, which often displayed disorganized, asymmetrical, or narrow and elongated morphologies. Formation of these abnormal bipolar spindles subsequently resulted in misalignment of metaphase chromosomes and ultimately caused a delay in the entry into anaphase. Moreover, such defects resulting from the T622A mutation were associated with a decrease in the rate of protein turnover at spindle microtubules. These findings suggest that Cdk1-cyclin B1-mediated phosphorylation of TMAP is important for and contributes to proper regulation of microtubule dynamics and establishment of functional bipolar spindles during mitosis.

Cdk1-Cyclin B1-mediated Phosphorylation of Tumor-associated Microtubule-associated Protein/Cytoskeleton-associated Protein 2 in Mitosis*

Science.gov (United States)

Uk Hong, Kyung; Kim, Hyun-Jun; Kim, Hyo-Sil; Seong, Yeon-Sun; Hong, Kyeong-Man; Bae, Chang-Dae; Park, Joobae

2009-01-01

During mitosis, establishment of structurally and functionally sound bipolar spindles is necessary for maintaining the fidelity of chromosome segregation. Tumor-associated microtubule-associated protein (TMAP), also known as cytoskeleton-associated protein 2 (CKAP2), is a mitotic spindle-associated protein whose level is frequently up-regulated in various malignancies. Previous reports have suggested that TMAP is a potential regulator of mitotic spindle assembly and dynamics and that it is required for chromosome segregation to occur properly. So far, there have been no reports on how its mitosis-related functions are regulated. Here, we report that TMAP is hyper-phosphorylated at the C terminus specifically during mitosis. At least four different residues (Thr-578, Thr-596, Thr-622, and Ser-627) were responsible for the mitosis-specific phosphorylation of TMAP. Among these, Thr-622 was specifically phosphorylated by Cdk1-cyclin B1 both in vitro and in vivo. Interestingly, compared with the wild type, a phosphorylation-deficient mutant form of TMAP, in which Thr-622 had been replaced with an alanine (T622A), induced a significant increase in the frequency of metaphase cells with abnormal bipolar spindles, which often displayed disorganized, asymmetrical, or narrow and elongated morphologies. Formation of these abnormal bipolar spindles subsequently resulted in misalignment of metaphase chromosomes and ultimately caused a delay in the entry into anaphase. Moreover, such defects resulting from the T622A mutation were associated with a decrease in the rate of protein turnover at spindle microtubules. These findings suggest that Cdk1-cyclin B1-mediated phosphorylation of TMAP is important for and contributes to proper regulation of microtubule dynamics and establishment of functional bipolar spindles during mitosis. PMID:19369249

Proteomic analysis of polyribosomes identifies splicing factors as potential regulators of translation during mitosis.

Science.gov (United States)

Aviner, Ranen; Hofmann, Sarah; Elman, Tamar; Shenoy, Anjana; Geiger, Tamar; Elkon, Ran; Ehrlich, Marcelo; Elroy-Stein, Orna

2017-06-02

Precise regulation of mRNA translation is critical for proper cell division, but little is known about the factors that mediate it. To identify mRNA-binding proteins that regulate translation during mitosis, we analyzed the composition of polysomes from interphase and mitotic cells using unbiased quantitative mass-spectrometry (LC-MS/MS). We found that mitotic polysomes are enriched with a subset of proteins involved in RNA processing, including alternative splicing and RNA export. To demonstrate that these may indeed be regulators of translation, we focused on heterogeneous nuclear ribonucleoprotein C (hnRNP C) as a test case and confirmed that it is recruited to elongating ribosomes during mitosis. Then, using a combination of pulsed SILAC, metabolic labeling and ribosome profiling, we showed that knockdown of hnRNP C affects both global and transcript-specific translation rates and found that hnRNP C is specifically important for translation of mRNAs that encode ribosomal proteins and translation factors. Taken together, our results demonstrate how proteomic analysis of polysomes can provide insight into translation regulation under various cellular conditions of interest and suggest that hnRNP C facilitates production of translation machinery components during mitosis to provide daughter cells with the ability to efficiently synthesize proteins as they enter G1 phase. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

Asymmetrical distribution of the transcriptionally competent NORs in mitosis

Czech Academy of Sciences Publication Activity Database

Kalmárová, Markéta; Kováčik, Lubomír; Popov, Alexey; Testillano, P. S.; Smirnov, Evgeny

2008-01-01

Roč. 163, č. 1 (2008), s. 40-44 ISSN 1047-8477 R&D Projects: GA ČR(CZ) GA304/06/1691 Grant - others:Wellcome Trust(XE) 075834/04/Z; GA MŠk(CZ) LC535; GA ČR(CZ) GA304/06/1662; C.S.I.C.(ES) CS-ES2007-8/16 Program:LC Institutional research plan: CEZ:AV0Z50110509 Keywords : mitosis * NORs * asymmetry Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 4.059, year: 2008

Heterologous expression of mammalian Plk1 in Drosophila reveals divergence from Polo during late mitosis

International Nuclear Information System (INIS)

Pearson, John; Godinho, Susana A.; Tavares, Alvaro; Glover, David M.

2006-01-01

Drosophila Polo kinase is the founder member of a conserved kinase family required for multiple stages of mitosis. We assessed the ability of mouse Polo-like kinase 1 (Plk1) to perform the multiple mitotic functions of Polo kinase, by expressing a Plk1-GFP fusion in Drosophila. Consistent with the previously reported localization of Polo kinase, Plk1-GFP was strongly localized to centrosomes and recruited to the centromeric regions of condensing chromosomes during early mitosis. However, in contrast to a functional Polo-GFP fusion, Plk1-GFP failed to localize to the central spindle midzone in both syncytial embryo mitosis and the conventional mitoses of cellularized embryos and S2 cells. Moreover, unlike endogenous Polo kinase and Polo-GFP, Plk1-GFP failed to associate with the contractile ring. Expression of Plk1-GFP enhanced the lethality of hypomorphic polo mutants and disrupted the organization of the actinomyosin cytoskeleton in a dominant-negative manner. Taken together, our results suggest that endogenous Polo kinase has specific roles in regulating actinomyosin rearrangements during Drosophila mitoses that its mammalian counterpart, Plk1, cannot fulfill. Consistent with this hypothesis, we observed defects in the cortical recruitment of myosin and myosin regulatory light chain in Polo deficient cells

INDEKS MITOSIS UJUNG AKAR KECAMBAH CABE BESAR (Capsicum annuum L. SETELAH PERLAKUAN SUSPENSI Trichoderma sp.

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PetroneLa Deno Raja

2016-06-01

Full Text Available Penelitian ini bertujuan untuk mengetahui indeks mitosis ujung akar kecambah cabe besar (Capsicum annuum L. setelah perlakuan suspensi Trichoderma sp. Penelitian ini dilakukan di laboratorium Struktur Perkembangan Tumbuhan Jurusan Biologi FMIPA, Universitas Udayana dari Oktober 2013-November 2013. Metode yang digunakan adalah metode squash, biji cabe untuk kontrol direndam dalam air ± 6 jam, untuk perlakuan biji setelah direndam air, direndam lagi dalam suspensi Trichoderma sp. 10-7 selama ± 6 jam, selanjutnya dikecambahkan. Ujung akar kecambah 2 mm dipotong, difiksasi dalam larutan farmer ± 2-24 jam, dihidrolisis dalam larutan 3N HCL ± 2-5 menit dan kemudian pewarnaan dengan aceto orcein ± 5 menit. Pengamatan dilakukan dengan mikroskop binokuler, data pembelahan tiap fase mitosis dihitung (%, dicatat dan difoto, dan dianalisis dengan menggunakan uji paired T tes.Hasil penelitian menunjukkan bahwa Trichoderma sp. berpengaruh terhadap indeks mitosis sel ujung akar Capsicum annuum L.,  pada fase metafase berbeda nyata antara kontrol dan perlakuan, sedangkan pada fase profase, anafase dan telofase berbeda tidak nyata.  Pada perlakuan persentase fase profase, metafase, anafase dan telofase (77,14%; 12,96 %; 5,88 % dan 5,23 % lebih tinggi dari kontrol (66,40 %; 5,44 %; 4,96 % dan 4,66 %.

Profiling the Interaction Mechanism of Quinoline/Quinazoline Derivatives as MCHR1 Antagonists: An in Silico Method

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Mingwei Wu

2014-09-01

Full Text Available Melanin concentrating hormone receptor 1 (MCHR1, a crucial regulator of energy homeostasis involved in the control of feeding and energy metabolism, is a promising target for treatment of obesity. In the present work, the up-to-date largest set of 181 quinoline/quinazoline derivatives as MCHR1 antagonists was subjected to both ligand- and receptor-based three-dimensional quantitative structure–activity (3D-QSAR analysis applying comparative molecular field analysis (CoMFA and comparative molecular similarity indices analysis (CoMSIA. The optimal predictable CoMSIA model exhibited significant validity with the cross-validated correlation coefficient (Q2 = 0.509, non-cross-validated correlation coefficient (R2ncv = 0.841 and the predicted correlation coefficient (R2pred = 0.745. In addition, docking studies and molecular dynamics (MD simulations were carried out for further elucidation of the binding modes of MCHR1 antagonists. MD simulations in both water and lipid bilayer systems were performed. We hope that the obtained models and information may help to provide an insight into the interaction mechanism of MCHR1 antagonists and facilitate the design and optimization of novel antagonists as anti-obesity agents.

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.

Mitosis detection in breast cancer histological images An ICPR 2012 contest

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Ludovic Roux

2013-01-01

Full Text Available Introduction: In the framework of the Cognitive Microscope (MICO project, we have set up a contest about mitosis detection in images of H and E stained slides of breast cancer for the conference ICPR 2012. Mitotic count is an important parameter for the prognosis of breast cancer. However, mitosis detection in digital histopathology is a challenging problem that needs a deeper study. Indeed, mitosis detection is difficult because mitosis are small objects with a large variety of shapes, and they can thus be easily confused with some other objects or artefacts present in the image. We added a further dimension to the contest by using two different slide scanners having different resolutions and producing red-green-blue (RGB images, and a multi-spectral microscope producing images in 10 different spectral bands and 17 layers Z-stack. 17 teams participated in the study and the best team achieved a recall rate of 0.7 and precision of 0.89. Context: Several studies on automatic tools to process digitized slides have been reported focusing mainly on nuclei or tubule detection. Mitosis detection is a challenging problem that has not yet been addressed well in the literature. Aims: Mitotic count is an important parameter in breast cancer grading as it gives an evaluation of the aggressiveness of the tumor. However, consistency, reproducibility and agreement on mitotic count for the same slide can vary largely among pathologists. An automatic tool for this task may help for reaching a better consistency, and at the same time reducing the burden of this demanding task for the pathologists. Subjects and Methods: Professor Frιdιrique Capron team of the pathology department at Pitiι-Salpκtriθre Hospital in Paris, France, has selected a set of five slides of breast cancer. The slides are stained with H and E. They have been scanned by three different equipments: Aperio ScanScope XT slide scanner, Hamamatsu NanoZoomer 2.0-HT slide scanner and 10 bands

Bora and Aurora-A continue to activate Plk1 in mitosis

Czech Academy of Sciences Publication Activity Database

Bruinsma, W.; Macůrek, Libor; Freire, R.; Lindqvist, A.; Medema, R.H.

2014-01-01

Roč. 127, č. 4 (2014), s. 801-811 ISSN 0021-9533 R&D Projects: GA ČR GA13-18392S Grant - others:Ministerio de Economía y Competitividad(ES) SAF2010-22357; CONSOLIDER-Ingenio(NL) CDS2007-0015 Keywords : Aurora-A * Bora * Mitosis * Plk1 Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 5.432, year: 2014

Thrombopoietin-induced Polyploidization of Bone Marrow Megakaryocytes Is Due to a Unique Regulatory Mechanism in Late Mitosis

Science.gov (United States)

Nagata, Yuka; Muro, Yoshinao; Todokoro, Kazuo

1997-01-01

Megakaryocytes undergo a unique differentiation program, becoming polyploid through repeated cycles of DNA synthesis without concomitant cell division. However, the mechanism underlying this polyploidization remains totally unknown. It has been postulated that polyploidization is due to a skipping of mitosis after each round of DNA replication. We carried out immunohistochemical studies on mouse bone marrow megakaryocytes during thrombopoietin- induced polyploidization and found that during this process megakaryocytes indeed enter mitosis and progress through normal prophase, prometaphase, metaphase, and up to anaphase A, but not to anaphase B, telophase, or cytokinesis. It was clearly observed that multiple spindle poles were formed as the polyploid megakaryocytes entered mitosis; the nuclear membrane broke down during prophase; the sister chromatids were aligned on a multifaced plate, and the centrosomes were symmetrically located on either side of each face of the plate at metaphase; and a set of sister chromatids moved into the multiple centrosomes during anaphase A. We further noted that the pair of spindle poles in anaphase were located in close proximity to each other, probably because of the lack of outward movement of spindle poles during anaphase B. Thus, the reassembling nuclear envelope may enclose all the sister chromatids in a single nucleus at anaphase and then skip telophase and cytokinesis. These observations clearly indicate that polyploidization of megakaryocytes is not simply due to a skipping of mitosis, and that the megakaryocytes must have a unique regulatory mechanism in anaphase, e.g., factors regulating anaphase such as microtubule motor proteins might be involved in this polyploidization process. PMID:9334347

Creating a Double-Spring Model to Teach Chromosome Movement during Mitosis & Meiosis

Science.gov (United States)

Luo, Peigao

2012-01-01

The comprehension of chromosome movement during mitosis and meiosis is essential for understanding genetic transmission, but students often find this process difficult to grasp in a classroom setting. I propose a "double-spring model" that incorporates a physical demonstration and can be used as a teaching tool to help students understand this…

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.

Breast cancer mitosis detection in histopathological images with spatial feature extraction

Science.gov (United States)

Albayrak, Abdülkadir; Bilgin, Gökhan

2013-12-01

In this work, cellular mitosis detection in histopathological images has been investigated. Mitosis detection is very expensive and time consuming process. Development of digital imaging in pathology has enabled reasonable and effective solution to this problem. Segmentation of digital images provides easier analysis of cell structures in histopathological data. To differentiate normal and mitotic cells in histopathological images, feature extraction step is very crucial step for the system accuracy. A mitotic cell has more distinctive textural dissimilarities than the other normal cells. Hence, it is important to incorporate spatial information in feature extraction or in post-processing steps. As a main part of this study, Haralick texture descriptor has been proposed with different spatial window sizes in RGB and La*b* color spaces. So, spatial dependencies of normal and mitotic cellular pixels can be evaluated within different pixel neighborhoods. Extracted features are compared with various sample sizes by Support Vector Machines using k-fold cross validation method. According to the represented results, it has been shown that separation accuracy on mitotic and non-mitotic cellular pixels gets better with the increasing size of spatial window.

Synthesis of Bioactive 2-(Arylaminothiazolo[5,4-f]-quinazolin-9-ones via the Hügershoff Reaction or Cu- Catalyzed Intramolecular C-S Bond Formation

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Damien Hédou

2016-06-01

Full Text Available A library of thirty eight novel thiazolo[5,4-f]quinazolin-9(8H-one derivatives (series 8, 10, 14 and 17 was prepared via the Hügershoff reaction and a Cu catalyzed intramolecular C-S bond formation, helped by microwave-assisted technology when required. The efficient multistep synthesis of the key 6-amino-3-cyclopropylquinazolin-4(3H-one (3 has been reinvestigated and performed on a multigram scale from the starting 5-nitroanthranilic acid. The inhibitory potency of the final products was evaluated against five kinases involved in Alzheimer’s disease and showed that some molecules of the 17 series described in this paper are particularly promising for the development of novel multi-target inhibitors of kinases.

Effects of radiation and porphyrin on mitosis and chromosomes in human hematopoietic cell lines

International Nuclear Information System (INIS)

Tan, J.C.; Huang, C.C.; Fiel, R.J.

1976-01-01

The effect on mitosis of a human hematopoietic cell line RPMI-1788 treated with a metal chelate (Zn ++ ) of meso-tetra (p-carboxyphenyl) porphine (Zn-TCPP) alone at various concentrations or in combination with gamma-irradiation at various doses were studied. The results showed that both Zn-TCPP and radiation were effective in interfering with normal mitosis and that the effect of radiation was relatively more effective. Data also suggest interacting effects between Zn-TCPP and gamma-irradiation. At low doses of radiation, Zn-TCPP potentiated the effect of radiation. The reverse seemed to be true at a high dose of radiation. The effects of two porphyrins (Zn-TCPP and hematoporphyrin) and radiation on chromosomes were also studied. Chromosomal aberrations characteristic of radiation were observed. The porphyrins were found not to be effective chromosome-breaking agents under the experimental conditions tested

Mto2 multisite phosphorylation inactivates non-spindle microtubule nucleation complexes during mitosis

Science.gov (United States)

Borek, Weronika E.; Groocock, Lynda M.; Samejima, Itaru; Zou, Juan; de Lima Alves, Flavia; Rappsilber, Juri; Sawin, Kenneth E.

2015-01-01

Microtubule nucleation is highly regulated during the eukaryotic cell cycle, but the underlying molecular mechanisms are largely unknown. During mitosis in fission yeast Schizosaccharomyces pombe, cytoplasmic microtubule nucleation ceases simultaneously with intranuclear mitotic spindle assembly. Cytoplasmic nucleation depends on the Mto1/2 complex, which binds and activates the γ-tubulin complex and also recruits the γ-tubulin complex to both centrosomal (spindle pole body) and non-centrosomal sites. Here we show that the Mto1/2 complex disassembles during mitosis, coincident with hyperphosphorylation of Mto2 protein. By mapping and mutating multiple Mto2 phosphorylation sites, we generate mto2-phosphomutant strains with enhanced Mto1/2 complex stability, interaction with the γ-tubulin complex and microtubule nucleation activity. A mutant with 24 phosphorylation sites mutated to alanine, mto2[24A], retains interphase-like behaviour even in mitotic cells. This provides a molecular-level understanding of how phosphorylation ‘switches off' microtubule nucleation complexes during the cell cycle and, more broadly, illuminates mechanisms regulating non-centrosomal microtubule nucleation. PMID:26243668

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

Analysis of structural and numerical chromosomal aberrations at the first and second mitosis after X irradiation of two-cell mouse embryos

International Nuclear Information System (INIS)

Weissenborn, U.; Streffer, C.

1989-01-01

Two-cell mouse embryos were X-irradiated in the late G2 phase in vivo. The first and second postradiation mitoses were analyzed for chromosomal anomalies. The majority of structural aberrations visible at the first mitosis after irradiation were chromatid breaks and chromatid gaps; only a few interchanges and dicentrics were observed. The aberration frequency resulted in a dose-effect relationship which was well described by a linear model. At the second mitosis 29% of the structural aberrations of the first mitosis were counted; the aberration quality changed only slightly. It is discussed whether these aberrations are to be considered new, derived, or unchanged transmitted aberrations. Contrary to the results obtained after irradiation of one-cell embryos, little chromosome loss was induced by radiation in two-cell embryos

The spatio-temporal dynamics of PKA activity profile during mitosis and its correlation to chromosome segregation

Science.gov (United States)

Vandame, Pauline; Spriet, Corentin; Trinel, Dave; Gelaude, Armance; Caillau, Katia; Bompard, Coralie; Biondi, Emanuele; Bodart, Jean-François

2014-01-01

The cyclic adenosine monophosphate dependent kinase protein (PKA) controls a variety of cellular processes including cell cycle regulation. Here, we took advantages of genetically encoded FRET-based biosensors, using an AKAR-derived biosensor to characterize PKA activity during mitosis in living HeLa cells using a single-cell approach. We measured PKA activity changes during mitosis. HeLa cells exhibit a substantial increase during mitosis, which ends with telophase. An AKAREV T>A inactive form of the biosensor and H89 inhibitor were used to ascertain for the specificity of the PKA activity measured. On a spatial point of view, high levels of activity near to chromosomal plate during metaphase and anaphase were detected. By using the PKA inhibitor H89, we assessed the role of PKA in the maintenance of a proper division phenotype. While this treatment in our hands did not impaired cell cycle progression in a drastic manner, inhibition of PKA leads to a dramatic increase in chromososme misalignement on the spindle during metaphase that could result in aneuploidies. Our study emphasizes the insights that can be gained with genetically encoded FRET-based biosensors, which enable to overcome the shortcomings of classical methologies and unveil in vivo PKA spatiotemporal profiles in HeLa cells. PMID:25485503

The spatio-temporal dynamics of PKA activity profile during mitosis and its correlation to chromosome segregation.

Science.gov (United States)

Vandame, Pauline; Spriet, Corentin; Trinel, Dave; Gelaude, Armance; Caillau, Katia; Bompard, Coralie; Biondi, Emanuele; Bodart, Jean-François

2014-01-01

The cyclic adenosine monophosphate dependent kinase protein (PKA) controls a variety of cellular processes including cell cycle regulation. Here, we took advantages of genetically encoded FRET-based biosensors, using an AKAR-derived biosensor to characterize PKA activity during mitosis in living HeLa cells using a single-cell approach. We measured PKA activity changes during mitosis. HeLa cells exhibit a substantial increase during mitosis, which ends with telophase. An AKAREV T>A inactive form of the biosensor and H89 inhibitor were used to ascertain for the specificity of the PKA activity measured. On a spatial point of view, high levels of activity near to chromosomal plate during metaphase and anaphase were detected. By using the PKA inhibitor H89, we assessed the role of PKA in the maintenance of a proper division phenotype. While this treatment in our hands did not impaired cell cycle progression in a drastic manner, inhibition of PKA leads to a dramatic increase in chromososme misalignement on the spindle during metaphase that could result in aneuploidies. Our study emphasizes the insights that can be gained with genetically encoded FRET-based biosensors, which enable to overcome the shortcomings of classical methologies and unveil in vivo PKA spatiotemporal profiles in HeLa cells.

TopBP1 is required at mitosis to reduce transmission of DNA damage to G1 daughter cells

Science.gov (United States)

Pedersen, Rune Troelsgaard; Kruse, Thomas; Nilsson, Jakob

2015-01-01

Genome integrity is critically dependent on timely DNA replication and accurate chromosome segregation. Replication stress delays replication into G2/M, which in turn impairs proper chromosome segregation and inflicts DNA damage on the daughter cells. Here we show that TopBP1 forms foci upon mitotic entry. In early mitosis, TopBP1 marks sites of and promotes unscheduled DNA synthesis. Moreover, TopBP1 is required for focus formation of the structure-selective nuclease and scaffold protein SLX4 in mitosis. Persistent TopBP1 foci transition into 53BP1 nuclear bodies (NBs) in G1 and precise temporal depletion of TopBP1 just before mitotic entry induced formation of 53BP1 NBs in the next cell cycle, showing that TopBP1 acts to reduce transmission of DNA damage to G1 daughter cells. Based on these results, we propose that TopBP1 maintains genome integrity in mitosis by controlling chromatin recruitment of SLX4 and by facilitating unscheduled DNA synthesis. PMID:26283799

Design, synthesis, molecular docking and anticonvulsant evaluation of novel 6-iodo-2-phenyl-3-substituted-quinazolin-4(3H-ones

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Mohamed-Kamal Ibrahim

2015-12-01

Full Text Available A new series of 6-iodo-2-phenyl-3-substituted-quinazolin-4(3H-one (5–12a–b derivatives were synthesized, evaluated for their anticonvulsant activity against pentylenetetrazole (PTZ-induced seizures and maximal electroshock test and compared with the reference drugs phenobarbital sodium and methaqualone. The neurotoxicity was assessed using rotarod test. The molecular docking was performed for all the synthesized compounds to assess their binding affinities to GABA-A receptor in order to rationalize their anticonvulsant activities in a qualitative way. The data obtained from the molecular modeling were correlated with those obtained from the biological screening. Compounds 9a, 9b, 12a and 7a showed the highest anticonvulsant activities of this series with relatively low neurotoxicity and low toxicity in the median lethal dose test when compared with the reference drugs. The obtained results proved that the most active compounds could be a useful model for future design, adaptation and investigation to construct more active analogs.

RECQ5 Helicase Cooperates with MUS81 Endonuclease in Processing Stalled Replication Forks at Common Fragile Sites during Mitosis

DEFF Research Database (Denmark)

Di Marco, Stefano; Hasanova, Zdenka; Kanagaraj, Radhakrishnan

2017-01-01

The MUS81-EME1 endonuclease cleaves late replication intermediates at common fragile sites (CFSs) during early mitosis to trigger DNA-repair synthesis that ensures faithful chromosome segregation. Here, we show that these DNA transactions are promoted by RECQ5 DNA helicase in a manner dependent...... on its Ser727 phosphorylation by CDK1. Upon replication stress, RECQ5 associates with CFSs in early mitosis through its physical interaction with MUS81 and promotes MUS81-dependent mitotic DNA synthesis. RECQ5 depletion or mutational inactivation of its ATP-binding site, RAD51-interacting domain...

How-to-Do-It: Hands-on Activity for Mitosis, Meiosis and the Fundamentals of Heredity.

Science.gov (United States)

Taylor, Mark F.

1988-01-01

Described is an exercise which uses inexpensive and easy-to-make materials to demonstrate the basic fundamentals of heredity. Discusses two approaches using a hypothetical insert to demonstrate inheritance, mitosis, meiosis, and genotypic and phenotypic frequencies. (CW)

Population control of resident and immigrant microglia by mitosis and apoptosis.

Science.gov (United States)

Wirenfeldt, Martin; Dissing-Olesen, Lasse; Anne Babcock, Alicia; Nielsen, Marianne; Meldgaard, Michael; Zimmer, Jens; Azcoitia, Iñigo; Leslie, Robert Graham Quinton; Dagnaes-Hansen, Frederik; Finsen, Bente

2007-08-01

Microglial population expansion occurs in response to neural damage via processes that involve mitosis and immigration of bone marrow-derived cells. However, little is known of the mechanisms that regulate clearance of reactive microglia, when microgliosis diminishes days to weeks later. We have investigated the mechanisms of microglial population control in a well-defined model of reactive microgliosis in the mouse dentate gyrus after perforant pathway axonal lesion. Unbiased stereological methods and flow cytometry demonstrate significant lesion-induced increases in microglial numbers. Reactive microglia often occurred in clusters, some having recently incorporated bromodeoxyuridine, showing that proliferation had occurred. Annexin V labeling and staining for activated caspase-3 and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling showed that apoptotic mechanisms participate in dissolution of the microglial response. Using bone marrow chimeric mice, we found that the lesion-induced proliferative capacity of resident microglia superseded that of immigrant microglia, whereas lesion-induced kinetics of apoptosis were comparable. Microglial numbers and responses were severely reduced in bone marrow chimeric mice. These results broaden our understanding of the microglial response to neural damage by demonstrating that simultaneously occurring mitosis and apoptosis regulate expansion and reduction of both resident and immigrant microglial cell populations.

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

Science.gov (United States)

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

Localization of spindle checkpoint proteins in cells undergoing mitosis with unreplicated genomes.

Science.gov (United States)

Johnson, Mary Kathrine; Cooksey, Amanda M; Wise, Dwayne A

2008-11-01

CHO cells can be arrested with hydoxyurea at the beginning of the DNA synthesis phase of the cell cycle. Subsequent treatment with the xanthine, caffeine, induces cells to bypass the S-phase checkpoint and enter unscheduled mitosis [Schlegel and Pardee,1986, Science 232:1264-1266]. These treated cells build a normal spindle and distribute kinetochores, unattached to chromosomes, to their daughter cells [Brinkley et al.,1988, Nature 336:251-254; Zinkowski et al.,1991, J Cell Biol 113:1091-1110; Wise and Brinkley,1997, Cell Motil Cytoskeleton 36:291-302; Balczon et al.,2003, Chromosoma 112:96-102]. To investigate how these cells distribute kinetochores to daughter cells, we analyzed the spindle checkpoint components, Mad2, CENP-E, and the 3F3 phosphoepitope, using immunofluorescence and digital microscopy. Even though the kinetochores were unpaired and DNA was fragmented, the tension, alignment, and motor components of the checkpoint were found to be present and localized as predicted in prometaphase and metaphase. This unusual mitosis proves that a cell can successfully localize checkpoint proteins and divide even when kinetochores are unpaired and fragmented. (c) 2008 Wiley-Liss, Inc.

Regulators of alternative polyadenylation operate at the transition from mitosis to meiosis.

Science.gov (United States)

Shan, Lingjuan; Wu, Chan; Chen, Di; Hou, Lei; Li, Xin; Wang, Lixia; Chu, Xiao; Hou, Yifeng; Wang, Zhaohui

2017-02-20

In the sexually reproductive organisms, gametes are produced by meiosis following a limited mitotic amplification. However, the intrinsic program switching cells from mitotic to meiotic cycle is unclear. Alternative polyadenylation (APA) is a highly conserved means of gene regulation and is achieved by the RNA 3'-processing machinery to generate diverse 3'UTR profiles. In Drosophila spermatogenesis, we observed distinct profiles of transcriptome-wide 3'UTR between mitotic and meiotic cells. In mutant germ cells stuck in mitosis, 3'UTRs of hundreds of genes were consistently shifted. Remarkably, altering the levels of multiple 3'-processing factors disrupted germline's progression to meiosis, indicative of APA's active role in this transition. An RNA-binding protein (RBP) Tut could directly bind 3'UTRs of 3'-processing factors whose expressions were repressed in the presence of Tut-containing complex. Further, we demonstrated that this RBP complex could execute the repression post-transcriptionally by recruiting CCR4/Twin of deadenylation complex. Thus, we propose that an RBP complex regulates the dynamic APA profile to promote the mitosis-to-meiosis transition. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Water droplet excess free energy determined by cluster mitosis using guided molecular dynamics

Science.gov (United States)

Lau, Gabriel V.; Hunt, Patricia A.; Müller, Erich A.; Jackson, George; Ford, Ian J.

2015-12-01

Atmospheric aerosols play a vital role in affecting climate by influencing the properties and lifetimes of clouds and precipitation. Understanding the underlying microscopic mechanisms involved in the nucleation of aerosol droplets from the vapour phase is therefore of great interest. One key thermodynamic quantity in nucleation is the excess free energy of cluster formation relative to that of the saturated vapour. In our current study, the excess free energy is extracted for clusters of pure water modelled with the TIP4P/2005 intermolecular potential using a method based on nonequilibrium molecular dynamics and the Jarzynski relation. The change in free energy associated with the "mitosis" or division of a cluster of N water molecules into two N/2 sub-clusters is evaluated. This methodology is an extension of the disassembly procedure used recently to calculate the excess free energy of argon clusters [H. Y. Tang and I. J. Ford, Phys. Rev. E 91, 023308 (2015)]. Our findings are compared to the corresponding excess free energies obtained from classical nucleation theory (CNT) as well as internally consistent classical theory (ICCT). The values of the excess free energy that we obtain with the mitosis method are consistent with CNT for large cluster sizes but for the smallest clusters, the results tend towards ICCT; for intermediate sized clusters, we obtain values between the ICCT and CNT predictions. Furthermore, the curvature-dependent surface tension which can be obtained by regarding the clusters as spherical droplets of bulk density is found to be a monotonically increasing function of cluster size for the studied range. The data are compared to other values reported in the literature, agreeing qualitatively with some but disagreeing with the values determined by Joswiak et al. [J. Phys. Chem. Lett. 4, 4267 (2013)] using a biased mitosis approach; an assessment of the differences is the main motivation for our current study.

Regulation of mitosis-meiosis transition by the ubiquitin ligase β-TrCP in male germ cells.

Science.gov (United States)

Nakagawa, Tadashi; Zhang, Teng; Kushi, Ryo; Nakano, Seiji; Endo, Takahiro; Nakagawa, Makiko; Yanagihara, Noriko; Zarkower, David; Nakayama, Keiko

2017-11-15

The mitosis-meiosis transition is essential for spermatogenesis. Specific and timely downregulation of the transcription factor DMRT1, and consequent induction of Stra8 expression, is required for this process in mammals, but the molecular mechanism has remained unclear. Here, we show that β-TrCP, the substrate recognition component of an E3 ubiquitin ligase complex, targets DMRT1 for degradation and thereby controls the mitosis-meiosis transition in mouse male germ cells. Conditional inactivation of β-TrCP2 in male germ cells of β-TrCP1 knockout mice resulted in sterility due to a lack of mature sperm. The β-TrCP-deficient male germ cells did not enter meiosis, but instead underwent apoptosis. The induction of Stra8 expression was also attenuated in association with the accumulation of DMRT1 at the Stra8 promoter in β-TrCP-deficient testes. DMRT1 contains a consensus β-TrCP degron sequence that was found to bind β-TrCP. Overexpression of β-TrCP induced the ubiquitylation and degradation of DMRT1. Heterozygous deletion of Dmrt1 in β-TrCP-deficient spermatogonia increased meiotic cells with a concomitant reduction of apoptosis. Collectively, our data indicate that β-TrCP regulates the transition from mitosis to meiosis in male germ cells by targeting DMRT1 for degradation. © 2017. Published by The Company of Biologists Ltd.

Dll1 maintains quiescence of adult neural stem cells and segregates asymmetrically during mitosis.

Science.gov (United States)

Kawaguchi, Daichi; Furutachi, Shohei; Kawai, Hiroki; Hozumi, Katsuto; Gotoh, Yukiko

2013-01-01

Stem cells often divide asymmetrically to produce one stem cell and one differentiating cell, thus maintaining the stem cell pool. Although neural stem cells (NSCs) in the adult mouse subventricular zone have been suggested to divide asymmetrically, intrinsic cell fate determinants for asymmetric NSC division are largely unknown. Stem cell niches are important for stem cell maintenance, but the niche for the maintenance of adult quiescent NSCs has remained obscure. Here we show that the Notch ligand Delta-like 1 (Dll1) is required to maintain quiescent NSCs in the adult mouse subventricular zone. Dll1 protein is induced in activated NSCs and segregates to one daughter cell during mitosis. Dll1-expressing cells reside in close proximity to quiescent NSCs, suggesting a feedback signal for NSC maintenance by their sister cells and progeny. Our data suggest a model in which NSCs produce their own niche cells for their maintenance through asymmetric Dll1 inheritance at mitosis.

Mitosis counting in breast cancer : object-level interobserver agreement and comparison to an automatic method

NARCIS (Netherlands)

Veta, M.; van Diest, P.J.; Jiwa, M.; Al-Janabi, S.; Pluim, J.P.W.

2016-01-01

BACKGROUND: Tumor proliferation speed, most commonly assessed by counting of mitotic figures in histological slide preparations, is an important biomarker for breast cancer. Although mitosis counting is routinely performed by pathologists, it is a tedious and subjective task with poor

Mitosis Counting in Breast Cancer : Object-Level Interobserver Agreement and Comparison to an Automatic Method

NARCIS (Netherlands)

Veta, Mitko; van Diest, Paul J; Jiwa, Mehdi; Al-Janabi, Shaimaa; Pluim, JPW

2016-01-01

BACKGROUND: Tumor proliferation speed, most commonly assessed by counting of mitotic figures in histological slide preparations, is an important biomarker for breast cancer. Although mitosis counting is routinely performed by pathologists, it is a tedious and subjective task with poor

A thermodynamic approach to the 'mitosis/apoptosis' ratio in cancer

Science.gov (United States)

Lucia, Umberto; Ponzetto, Antonio; Deisboeck, Thomas S.

2015-10-01

Cancer can be considered as an open, complex, (bio-thermo)dynamic and self-organizing system. Consequently, an entropy generation approach has been employed to analyze its mitosis/apoptosis ratio. Specifically, a novel thermodynamic anticancer strategy is suggested, based on the variation of entropy generation caused by the application of external fields, for example electro-magnetic fields, for therapeutic purposes. Eventually, this innovative approach could support conventional therapies, particularly for inoperable tumors or advanced stages of cancer, when larger tumor burden is diagnosed, and therapeutic options are often limited.

A comparison of G2 phase radiation-induced chromatid break kinetics using calyculin-PCC with those obtained using colcemid block.

Science.gov (United States)

Bryant, Peter E; Mozdarani, Hossein

2007-09-01

To study the possible influence of cell-cycle delay on cells reaching mitosis during conventional radiation-induced chromatid break experiments using colcemid as a blocking agent, we have compared the chromatid break kinetics following a single dose of gamma rays (0.75 Gy) in metaphase CHO cells using calyculin-induced premature chromosome condensation (PCC), with those using colcemid block. Calyculin-induced PCC causes very rapid condensation of G2 cell chromosomes without the need for a cell to progress to mitosis, hence eliminating any effect of cell-cycle checkpoint on chromatid break frequency. We found that the kinetics of the exponential first-order decrease in chromatid breaks with time after irradiation was similar (not significantly different) between the two methods of chromosome condensation. However, use of the calyculin-PCC technique resulted in a slightly increased rate of disappearance of chromatid breaks and thus higher frequencies of breaks at 1.5 and 2.5 h following irradiation. We also report on the effect of the nucleoside analogue ara A on chromatid break kinetics using the two chromosome condensation techniques. Ara A treatment of cells abrogated the decrease in chromatid breaks with time, both using the calyculin-PCC and colcemid methods. We conclude that cell-cycle delay may be a factor determining the absolute frequency of chromatid breaks at various times following irradiation of cells in G2 phase but that the first-order disappearance of chromatid breaks with time and its abrogation by ara A are not significantly influenced by the G2 checkpoint.

Plant WEE1 kinase is cell cycle regulated and removed at mitosis via the 26S proteasome machinery

Science.gov (United States)

Cook, Gemma S.; Grønlund, Anne Lentz; Siciliano, Ilario; Spadafora, Natasha; Amini, Maryam; Herbert, Robert J.; Bitonti, M. Beatrice; Graumann, Katja; Francis, Dennis; Rogers, Hilary J.

2013-01-01

In yeasts and animals, premature entry into mitosis is prevented by the inhibitory phosphorylation of cyclin-dependent kinase (CDK) by WEE1 kinase, and, at mitosis, WEE1 protein is removed through the action of the 26S proteasome. Although in higher plants WEE1 function has been confirmed in the DNA replication checkpoint, Arabidopsis wee1 insertion mutants grow normally, and a role for the protein in the G2/M transition during an unperturbed plant cell cycle is yet to be confirmed. Here data are presented showing that the inhibitory effect of WEE1 on CDK activity in tobacco BY-2 cell cultures is cell cycle regulated independently of the DNA replication checkpoint: it is high during S-phase but drops as cells traverse G2 and enter mitosis. To investigate this mechanism further, a yeast two-hybrid screen was undertaken to identify proteins interacting with Arabidopsis WEE1. Three F-box proteins and a subunit of the proteasome complex were identified, and bimolecular fluorescence complementation confirmed an interaction between AtWEE1 and the F-box protein SKP1 INTERACTING PARTNER 1 (SKIP1). Furthermore, the AtWEE1–green fluorescent protein (GFP) signal in Arabidopsis primary roots treated with the proteasome inhibitor MG132 was significantly increased compared with mock-treated controls. Expression of AtWEE1–YFPC (C-terminal portion of yellow fluorescent protein) or AtWEE1 per se in tobacco BY-2 cells resulted in a premature increase in the mitotic index compared with controls, whereas co-expression of AtSKIP1–YFPN negated this effect. These data support a role for WEE1 in a normal plant cell cycle and its removal at mitosis via the 26S proteasome. PMID:23536609

Discovery of potent and selective cytotoxic activity of new quinazoline-ureas against TMZ-resistant glioblastoma multiforme (GBM).

Science.gov (United States)

Elkamhawy, Ahmed; Viswanath, Ambily Nath Indu; Pae, Ae Nim; Kim, Hyeon Young; Heo, Jin-Chul; Park, Woo-Kyu; Lee, Chong-Ock; Yang, Heekyoung; Kim, Kang Ho; Nam, Do-Hyun; Seol, Ho Jun; Cho, Heeyeong; Roh, Eun Joo

2015-10-20

Herein, we report new quinazoline-urea based compounds with potent cytotoxic activities against TMZ-resistant glioblastoma multiforme (GBM) cells. Low micromolar IC₅₀ values were exhibited over a panel of three primary GBM patient-derived cell cultures belonging to proneural (GBM-1), mesenchymal (GBM-2), and classical (GBM-3) subtypes. Eight compounds showed excellent selectivity indices for GBM cells comparing to a normal astrocyte cell line. In JC-1 assay, analogues 11, 12, 20, 22, and 24 exerted promising rates of mPTP opening induction towards proneural GBM subtype. Compounds 11, 20, and 24 bound to the translocator protein 18 kDa (TSPO) in submicromolar range using [(3)H] PK-11195 binding affinity assay. A homology model was built and docked models of 11, 12, 20, 22 and 24 were generated for describing their plausible binding modes in TSPO. In 3D clonogenic assay, compound 20 manifested potent tumoricidal effects on TMZ-resistant GBM cells even at submicromolar concentrations. In addition, CYP450 and hERG assays presented a safe toxicity profile of 20. Taken as a whole, this report presents compound 20 as a potent, selective and safe GBM cytotoxic agent which constitutes a promising direction against TMZ-resistant GBM. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Nucleolus disassembly in mitosis and apoptosis: dynamic redistribution of phosphorylated-c-Myc, fibrillarin and Ki-67

Directory of Open Access Journals (Sweden)

C Soldani

2009-06-01

Full Text Available The nucleolus may undergo disassembly either reversibly during mitosis, or irreversibly in apoptosis, thus allowing the redistribution of the nucleolar proteins.We investigated here by immunocytochemistry the fate of three representative proteins, namely phosphorylated c-Myc, fibrillarin and Ki-67, and found that they behave independently in both processes: they relocate in distinct compartments during mitosis, whereas during apoptosis they may either be cleaved (Ki-67 or be extruded into the cytoplasm with a different kinetics and following an ordered, non chaotic program. The separation of these nucleolar proteins which occurs in early apoptotic nuclei continues also in the cytoplasm, and culminates in the final formation of apoptotic blebs containing different nucleolar proteins: this evidence confirms that the apoptotic bodies may be variable in size, content and surface reactivity, and include heterogeneous aggregates of nuclear proteins and/or nucleic acids.

Control of mitosis in Physarum polycephalum. The effect of lowering the DNA: mass ratio by uv irradiation

International Nuclear Information System (INIS)

Sudbery, P.E.; Grant, W.D.

1975-01-01

A model for the control of mitosis is presented and, along with four other models described previously, is tested by the response of Physarum polycephalum to uv irradiation. Plasmodia were irradiated following the second mitosis (M II) after fusion of microplasmodia. As shown by other authors, the onset of the next mitosis (M III) was delayed but the period M III-M IV was shortened relative to control plasmodia. It is shown that the period M III-M IV cannot be shortened beyond a minimum of 6 h despite increasing doses of uv. This minimum length is shown to be relatively independent of growth rate. If conditions were such that the length of M III-M IV was shortened to this minimum value the length of M IV-M V was also shorter than the corresponding control period. If the period M II-M IV was longer than the minimum following irradiation then the length of M IV-M V was not shortened. It is argued that only the latter situation allows models to be tested and it is shown how the observed result is consistent with only two of the five models considered. A further test compared the length of M III-M IV under these conditions with that predicted from the amount of DNA destroyed by the uv. This result was consistent only with the same two models

PGRMC1 participates in late events of bovine granulosa cells mitosis and oocyte meiosis.

Science.gov (United States)

Terzaghi, L; Tessaro, I; Raucci, F; Merico, V; Mazzini, G; Garagna, S; Zuccotti, M; Franciosi, F; Lodde, V

2016-08-02

Progesterone Receptor Membrane Component 1 (PGRMC1) is expressed in both oocyte and ovarian somatic cells, where it is found in multiple cellular sub-compartments including the mitotic spindle apparatus. PGRMC1 localization in the maturing bovine oocytes mirrors its localization in mitotic cells, suggesting a possible common action in mitosis and meiosis. To test the hypothesis that altering PGRMC1 activity leads to similar defects in mitosis and meiosis, PGRMC1 function was perturbed in cultured bovine granulosa cells (bGC) and maturing oocytes and the effect on mitotic and meiotic progression assessed. RNA interference-mediated PGRMC1 silencing in bGC significantly reduced cell proliferation, with a concomitant increase in the percentage of cells arrested at G2/M phase, which is consistent with an arrested or prolonged M-phase. This observation was confirmed by time-lapse imaging that revealed defects in late karyokinesis. In agreement with a role during late mitotic events, a direct interaction between PGRMC1 and Aurora Kinase B (AURKB) was observed in the central spindle at of dividing cells. Similarly, treatment with the PGRMC1 inhibitor AG205 or PGRMC1 silencing in the oocyte impaired completion of meiosis I. Specifically the ability of the oocyte to extrude the first polar body was significantly impaired while meiotic figures aberration and chromatin scattering within the ooplasm increased. Finally, analysis of PGRMC1 and AURKB localization in AG205-treated oocytes confirmed an altered localization of both proteins when meiotic errors occur. The present findings demonstrate that PGRMC1 participates in late events of both mammalian mitosis and oocyte meiosis, consistent with PGRMC1's localization at the mid-zone and mid-body of the mitotic and meiotic spindle.

Arrest of irradiated G1, S, or G2 cells at mitosis using nocodazole promotes repair of potentially lethal damage

International Nuclear Information System (INIS)

Iliakis, G.; Nuesse, M.

1984-01-01

The ability of synchronized Ehrlich ascites tumor cells, irradiated in G1, S, and G2 phases, to repair potentially lethal damage when arrested at mitosis by using 0.4 μg/ml nocodazole, a specific inhibitor of microtubule polymerization, has been studied. Cells irradiated in these phases were found to repair potentially lethal damage at mitosis. The extent of this repair was similar to that observed for cells irradiated at the same stages in the cell cycle but allowed to repair potentially lethal damage by incubating in balanced salt solution for 6 hr after X irradiation

The G2/M DNA damage checkpoint inhibits mitosis through Tyr15 phosphorylation of p34cdc2 in Aspergillus nidulans.

OpenAIRE

Ye, X S; Fincher, R R; Tang, A; Osmani, S A

1997-01-01

It is possible to cause G2 arrest in Aspergillus nidulans by inactivating either p34cdc2 or NIMA. We therefore investigated the negative control of these two mitosis-promoting kinases after DNA damage. DNA damage caused rapid Tyr15 phosphorylation of p34cdc2 and transient cell cycle arrest but had little effect on the activity of NIMA. Dividing cells deficient in Tyr15 phosphorylation of p34cdc2 were sensitive to both MMS and UV irradiation and entered lethal premature mitosis with damaged DN...

Replication stress activates DNA repair synthesis in mitosis

DEFF Research Database (Denmark)

Minocherhomji, Sheroy; Ying, Songmin; Bjerregaard, Victoria A

2015-01-01

Oncogene-induced DNA replication stress has been implicated as a driver of tumorigenesis. Many chromosomal rearrangements characteristic of human cancers originate from specific regions of the genome called common fragile sites (CFSs). CFSs are difficult-to-replicate loci that manifest as gaps...... into mitotic prophase triggers the recruitment of MUS81 to CFSs. The nuclease activity of MUS81 then promotes POLD3-dependent DNA synthesis at CFSs, which serves to minimize chromosome mis-segregation and non-disjunction. We propose that the attempted condensation of incompletely duplicated loci in early...... mitosis serves as the trigger for completion of DNA replication at CFS loci in human cells. Given that this POLD3-dependent mitotic DNA synthesis is enhanced in aneuploid cancer cells that exhibit intrinsically high levels of chromosomal instability (CIN(+)) and replicative stress, we suggest...

iDermatoPath - a novel software tool for mitosis detection in H&E-stained tissue sections of malignant melanoma.

Science.gov (United States)

Andres, C; Andres-Belloni, B; Hein, R; Biedermann, T; Schäpe, A; Brieu, N; Schönmeyer, R; Yigitsoy, M; Ring, J; Schmidt, G; Harder, N

2017-07-01

Malignant Melanoma (MM) is characterized by a growing incidence and a high malignant potential. Besides well-defined prognostic factors such as tumour thickness and ulceration, the Mitotic Rate (MR) was included in the AJCC recommendations for diagnosis and treatment of MM. In daily routine, the identification of a single mitosis can be difficult on haematoxylin and eosin slides alone. Several studies showed a big inter- and intra-individual variability in detecting the MR in MM even by very experienced investigators, thus raising the question for a computer-assisted method. The objective was to develop a software system for mitosis detection in MM on H&E slides based on machine learning for diagnostic support. We developed a computer-aided staging support system based on image analysis and machine learning on the basis of 59 MM specimens. Our approach automatically detects tumour regions, identifies mitotic nuclei and classifies them with respect to their diagnostic relevance. A convenient user interface enables the investigator to browse through the proposed mitoses for fast and efficient diagnosing. A quantitative evaluation on manually labelled ground truth data revealed that the tumour region detection yields a medium spatial overlap index (dice coefficient) of 0.72. For the mitosis detection, we obtained high accuracies of above 83%. On the technical side, the developed iDermatoPath software tool provides a novel approach for mitosis detection in MM, which can be further improved using more training data such as dermatopathologist annotations. On the practical side, a first evaluation of the clinical utility was positive, albeit this approach provides most benefit for difficult cases in a research setting. Assuming all slides to be digitally processed and reported in the near future, this method could become a helpful additional tool for the pathologist. © 2017 European Academy of Dermatology and Venereology.

PCTAIRE1 phosphorylates p27 and regulates mitosis in cancer cells.

Science.gov (United States)

Yanagi, Teruki; Krajewska, Maryla; Matsuzawa, Shu-ichi; Reed, John C

2014-10-15

PCTAIRE1 is distant relative of the cyclin-dependent kinase family that has been implicated in spermatogenesis and neuronal development, but it has not been studied in cancer. Here, we report that PCTAIRE1 is expressed in prostate, breast, and cervical cancer cells, where its RNAi-mediated silencing causes growth inhibition with aberrant mitosis due to defects in centrosome dynamics. PCTAIRE1 was not similarly involved in proliferation of nontransformed cells, including diploid human IMR-90 fibroblasts. Through yeast two-hybrid screening, we identified tumor suppressor p27 as a PCTAIRE1 interactor. In vitro kinase assays showed PCTAIRE1 phosphorylates p27 at Ser10. PCTAIRE1 silencing modulated Ser10 phosphorylation on p27 and led to its accumulation in cancer cells but not in nontransformed cells. In a mouse xenograft model of PPC1 prostate cancer, conditional silencing of PCTAIRE1 restored p27 protein expression and suppressed tumor growth. Mechanistic studies in HeLa cells showed that PCTAIRE1 phosphorylates p27 during the S and M phases of the cell cycle. Notably, p27 silencing was sufficient to rescue cells from mitotic arrest caused by PCTAIRE1 silencing. Clinically, PCTAIRE1 was highly expressed in primary breast and prostate tumors compared with adjacent normal epithelial tissues. Together our findings reveal an unexpected role for PCTAIRE1 in regulating p27 stability, mitosis, and tumor growth, suggesting PCTAIRE1 as a candidate cancer therapeutic target. ©2014 American Association for Cancer Research.

Dbf4-dependent kinase and the Rtt107 scaffold promote Mus81-Mms4 resolvase activation during mitosis.

Science.gov (United States)

Princz, Lissa N; Wild, Philipp; Bittmann, Julia; Aguado, F Javier; Blanco, Miguel G; Matos, Joao; Pfander, Boris

2017-03-01

DNA repair by homologous recombination is under stringent cell cycle control. This includes the last step of the reaction, disentanglement of DNA joint molecules (JMs). Previous work has established that JM resolving nucleases are activated specifically at the onset of mitosis. In case of budding yeast Mus81-Mms4, this cell cycle stage-specific activation is known to depend on phosphorylation by CDK and Cdc5 kinases. Here, we show that a third cell cycle kinase, Cdc7-Dbf4 (DDK), targets Mus81-Mms4 in conjunction with Cdc5-both kinases bind to as well as phosphorylate Mus81-Mms4 in an interdependent manner. Moreover, DDK-mediated phosphorylation of Mms4 is strictly required for Mus81 activation in mitosis, establishing DDK as a novel regulator of homologous recombination. The scaffold protein Rtt107, which binds the Mus81-Mms4 complex, interacts with Cdc7 and thereby targets DDK and Cdc5 to the complex enabling full Mus81 activation. Therefore, Mus81 activation in mitosis involves at least three cell cycle kinases, CDK, Cdc5 and DDK Furthermore, tethering of the kinases in a stable complex with Mus81 is critical for efficient JM resolution. © 2017 The Authors. Published under the terms of the CC BY NC ND 4.0 license.

Centrioles: active players or passengers during mitosis?

Science.gov (United States)

Debec, Alain; Sullivan, William; Bettencourt-Dias, Monica

2010-07-01

Centrioles are cylinders made of nine microtubule (MT) triplets present in many eukaryotes. Early studies, where centrosomes were seen at the poles of the mitotic spindle led to their coining as "the organ for cell division". However, a variety of subsequent observational and functional studies showed that centrosomes might not always be essential for mitosis. Here we review the arguments in this debate. We describe the centriole structure and its distribution in the eukaryotic tree of life and clarify its role in the organization of the centrosome and cilia, with an historical perspective. An important aspect of the debate addressed in this review is how centrioles are inherited and the role of the spindle in this process. In particular, germline inheritance of centrosomes, such as their de novo formation in parthenogenetic species, poses many interesting questions. We finish by discussing the most likely functions of centrioles and laying out new research avenues.

Mitosis delay in cells of the root meristem of pea seedlings in S and G2-phases when irradiated with gamma-rays

International Nuclear Information System (INIS)

Gudkov, I.N.; Zezina, N.V.

1976-01-01

Irradiation (800 rads) of pea seedlings, synchronized by a 24-hr treatment with 0.03% hydroxyurea, at the stage of G 1 →S, induced a 12-hr delay of mitosis peak; an 8-hr delay, in the early S-phase; a 4-hr delay, in the middle of S-phase; a 10-hr delay in the late S- and a 14-16-hr delay, in G 2 -phase. The number of cells having chromosome aberrations at the mitosis peak was similar in all the phases under study

From equator to pole: splitting chromosomes in mitosis and meiosis

Science.gov (United States)

Duro, Eris

2015-01-01

During eukaryotic cell division, chromosomes must be precisely partitioned to daughter cells. This relies on a mechanism to move chromosomes in defined directions within the parental cell. While sister chromatids are segregated from one another in mitosis and meiosis II, specific adaptations enable the segregation of homologous chromosomes during meiosis I to reduce ploidy for gamete production. Many of the factors that drive these directed chromosome movements are known, and their molecular mechanism has started to be uncovered. Here we review the mechanisms of eukaryotic chromosome segregation, with a particular emphasis on the modifications that ensure the segregation of homologous chromosomes during meiosis I. PMID:25593304

Regulatory Control of the Resolution of DNA Recombination Intermediates during Meiosis and Mitosis

OpenAIRE

Matos, Joao; Blanco, Miguel G.; Maslen, Sarah; Skehel, J. Mark; West, Stephen C.

2011-01-01

The efficient and timely resolution of DNA recombination intermediates is essential for bipolar chromosome segregation. Here, we show that the specialized chromosome segregation patterns of meiosis and mitosis, which require the coordination of recombination with cell-cycle progression, are achieved by regulating the timing of activation of two crossover-promoting endonucleases. In yeast meiosis, Mus81-Mms4 and Yen1 are controlled by phosphorylation events that lead to their sequential activa...

[Tripartite motif-containing protein 34 (TRIM34) colocalized with micronuclei chromosome and hampers its movement to equatorial plate during the metaphase stage of mitosis].

Science.gov (United States)

Sun, Dakang; An, Xinye; Ji, Bing; Cheng, Yanli; Gao, Honglian; Tian, Mingming

2016-06-01

Objective To examine whether tripartite motif-containing protein 34 (TRIM34) is colocalized with micronuclei and investigate the influence on the movement of micronuclei chromosome in mitosis. Methods The eukaryotic expression vector TRIM34-pEGFP-N3 was constructed, identified and then transfected into HEK293T cells. With 4', 6-diamidino-2-phenylindole 2HCI (DAPI) staining, the colocalization between TRIM34 and micronuclei was observed under a fluorescence microscope. Moreover, MitoTracker(R)Deep Red was used to identify the colocalization between the complex of TRIM34-micronulei and mitochondria under a confocal microscope. Finally, the effect of TRIM34 on the movement of micronuclei chromosome in mitosis was examined. Results DNA sequencing confirmed that the vector TRIM34-pEGFP-N3 was constructed successfully. A fluorescence microscope revealed that TRIM34 could be colocalized with micronuclei in HEK293T cells transfected with TRIM34-pEGFP-N3. In the same manner, a confocal microscope distinctly showed that TRIM34 was colocalized with micronuclei similarly in appearance. However, there was no distinguished colocalization relationship between the complex of TRIM34-micronulei and mitochondria. Interestingly, the micronuclei chromosome conjugated with TRIM34 was hardly transferred to equatorial plate during the metaphase stage of mitosis. Conclusion TRIM34 is colocalized with micronuclei chromosome and hampers its movement to equatorial plate in mitosis.

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

Przebieg mitozy w korzeniach siewek pszenicy pod wpływem rubidu [Course of mitosis in root seedlings of Triticum aestivum L. under the influence of rubidium

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Kazimierz Olech

2015-06-01

Full Text Available The depresion of mitosis as a result of rubidium action illustrated by the lower frequency of mitosis was found in an investigation made on roots of wheat seedlings grown on a nutrient medium which the total amount of potassium or a half of it was replaced by rubidium. The lower mitotic activity was caused by limited number of nuclei beginning prophase and by a prolonged duration of metaphase.

Late division kinetics in relation to modification of protein synthesis in mouse eggs blocked in the G2 phase after X-irradiation; and comment

International Nuclear Information System (INIS)

Grinfeld, S.; Gilles, J.; Jacquet, P.; Baugnet-Mahieu, L.; Rowley, R.

1987-01-01

Mouse zygotes (BALB/c blocked in the G 2 phase of the first cell cycle after X-irradiation were allowed to develop in culture medium. Delayed cleavage occurred at the same time in embryos exposed to 1 or 2 Gy and late division coincided with the second division in controls. Two dimensional electrophoresis showed that blocked irradiated embryos underwent the same modifications in protein synthesis as control embryos of the same age, except during first mitosis, for three polypeptide sets of 30, 35 and 45 kilodaltons molecular weight. The most remarkable difference between them was the appearance in cleaving controls of three spots at 35 kilodaltons that were absent in blocked irradiated embryos. It is assumed that blocked embryos 'missed' some signal necessary for cell division, but remained ready to cleave when a second signal occurred. Eggs from the BALB/c strain were particularly susceptible to this effect of X-irradiation but it was also found in eggs from other strains, irradiated with much higher doses. The accompanying comment by Rowley discusses the point of interruption of the control mechanism and the nature of the lesions involved. (author)

Mitosis can drive cell cannibalism through entosis

Science.gov (United States)

Durgan, Joanne; Tseng, Yun-Yu; Hamann, Jens C; Domart, Marie-Charlotte; Collinson, Lucy; Overholtzer, Michael; Florey, Oliver

2017-01-01

Entosis is a form of epithelial cell cannibalism that is prevalent in human cancer, typically triggered by loss of matrix adhesion. Here, we report an alternative mechanism for entosis in human epithelial cells, driven by mitosis. Mitotic entosis is regulated by Cdc42, which controls mitotic morphology. Cdc42 depletion enhances mitotic deadhesion and rounding, and these biophysical changes, which depend on RhoA activation and are phenocopied by Rap1 inhibition, permit subsequent entosis. Mitotic entosis occurs constitutively in some human cancer cell lines and mitotic index correlates with cell cannibalism in primary human breast tumours. Adherent, wild-type cells can act efficiently as entotic hosts, suggesting that normal epithelia may engulf and kill aberrantly dividing neighbours. Finally, we report that Paclitaxel/taxol promotes mitotic rounding and subsequent entosis, revealing an unconventional activity of this drug. Together, our data uncover an intriguing link between cell division and cannibalism, of significance to both cancer and chemotherapy. DOI: http://dx.doi.org/10.7554/eLife.27134.001 PMID:28693721

Cdc42 is not essential for filopodium formation, directed migration, cell polarization, and mitosis in fibroblastoid cells

DEFF Research Database (Denmark)

Czuchra, Aleksandra; Wu, Xunwei; Meyer, Hannelore

2005-01-01

of Cdc42 did not affect filopodium or lamellipodium formation and had no significant influence on the speed of directed migration nor on mitosis. Cdc42-deficient cells displayed a more elongated cell shape and had a reduced area. Furthermore, directionality during migration and reorientation of the Golgi...

Golgi twins in late mitosis revealed by genetically encoded tags for live cell imaging and correlated electron microscopy

NARCIS (Netherlands)

Gaietta, Guido M; Giepmans, Ben N G; Deerinck, Thomas J; Smith, W Bryan; Ngan, Lucy; Llopis, Juan; Adams, Stephen R; Tsien, Roger Y; Ellisman, Mark H

2006-01-01

Combinations of molecular tags visible in light and electron microscopes become particularly advantageous in the analysis of dynamic cellular components like the Golgi apparatus. This organelle disassembles at the onset of mitosis and, after a sequence of poorly understood events, reassembles after

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

Progesterone Receptor Membrane Component 1 (PGRMC1 in cell division: its role in bovine granulosa cells mitosis

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Laura Terzaghi

2015-07-01

Full Text Available The present studies were aimed to assess Progesterone Receptor Membrane Component-1 (PGRMC1 role in regulating bovine granulosa cells (bGC mitosis. First, we performed immunofluorescence studies on in vitro cultured bGC collected from antral follicles, which showed that PGRMC1 localizes to the spindle apparatus in mitotic cells. Then, to evaluate PGRMC1 effect on cell proliferation we silenced its expression with RNA interference technique (RNAi. Quantitative RT-PCR and immunoblotting confirmed down-regulation of PGRMC1 expression, when compared to CTRL-RNAi treated bGC (p<0.05. After 72h of culture, PGRMC1 silencing determined a lower growth rate (p<0.05 and a higher percentage of cells arrested at G2/M phase as assessed by flowcytometry (p<0.05. Accordingly, live imaging studies revealed more aberrant mitosis and a delayed M-phase in PGRMC1-RNAi treated cells compared to CTRL-RNAi group (p<0.05. These data confirmed that PGRMC1 is directly involved in bGC mitosis and ongoing preliminary studies are aimed to elucidate its putative mechanisms of action. Since PGRMC1 is a membrane protein, we hypothesize its possible involvement in vesicular trafficking and endocytosis, which is in turn an important process to assure proper cell division. To assess this hypothesis, we have preliminarily conducted immunofluorescence and in situ proximity ligation assay experiments that showed PGRMC1 co-localization and direct interaction with clathrin. This is important since clathrin is an essential protein for both endosomes formation, and cell division acting directly on the spindle apparatus. Thus our studies set the stage for analysis aimed to further characterize PGRMC1’s mechanism of action in mitotic cell.

Regulation of mitosis by the NIMA kinase involves TINA and its newly discovered partner, An-WDR8, at spindle pole bodies

Science.gov (United States)

Shen, Kuo-Fang; Osmani, Stephen A.

2013-01-01

The NIMA kinase is required for mitotic nuclear pore complex disassembly and potentially controls other mitotic-specific events. To investigate this possibility, we imaged NIMA–green fluorescent protein (GFP) using four-dimensional spinning disk confocal microscopy. At mitosis NIMA-GFP locates to spindle pole bodies (SPBs), which contain Cdk1/cyclin B, followed by Aurora, TINA, and the BimC kinesin. NIMA promotes NPC disassembly in a spatially regulated manner starting near SPBs. NIMA is also required for TINA, a NIMA-interacting protein, to locate to SPBs during initiation of mitosis, and TINA is then necessary for locating NIMA back to SPBs during mitotic progression. To help expand the NIMA-TINA pathway, we affinity purified TINA and found it to uniquely copurify with An-WDR8, a WD40-domain protein conserved from humans to plants. Like TINA, An-WDR8 accumulates within nuclei during G2 but disperses from nuclei before locating to mitotic SPBs. Without An-WDR8, TINA levels are greatly reduced, whereas TINA is necessary for mitotic targeting of An-WDR8. Finally, we show that TINA is required to anchor mitotic microtubules to SPBs and, in combination with An-WDR8, for successful mitosis. The findings provide new insights into SPB targeting and indicate that the mitotic microtubule-anchoring system at SPBs involves WDR8 in complex with TINA. PMID:24152731

Population control of resident and immigrant microglia by mitosis and apoptosis

DEFF Research Database (Denmark)

Wirenfeldt, Martin; Dissing-Olesen, Lasse; Babcock, Alicia

2007-01-01

microglia often occurred in clusters, some having recently incorporated bromodeoxyuridine, showing that proliferation had occurred. Annexin V labeling and staining for activated caspase-3 and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling showed that apoptotic mechanisms participate...... in dissolution of the microglial response. Using bone marrow chimeric mice, we found that the lesion-induced proliferative capacity of resident microglia superseded that of immigrant microglia, whereas lesion-induced kinetics of apoptosis were comparable. Microglial numbers and responses were severely reduced...... in bone marrow chimeric mice. These results broaden our understanding of the microglial response to neural damage by demonstrating that simultaneously occurring mitosis and apoptosis regulate expansion and reduction of both resident and immigrant microglial cell populations....

An efficient, block-by-block algorithm for inverting a block tridiagonal, nearly block Toeplitz matrix

International Nuclear Information System (INIS)

Reuter, Matthew G; Hill, Judith C

2012-01-01

We present an algorithm for computing any block of the inverse of a block tridiagonal, nearly block Toeplitz matrix (defined as a block tridiagonal matrix with a small number of deviations from the purely block Toeplitz structure). By exploiting both the block tridiagonal and the nearly block Toeplitz structures, this method scales independently of the total number of blocks in the matrix and linearly with the number of deviations. Numerical studies demonstrate this scaling and the advantages of our method over alternatives.

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

Phospho-H1 Decorates the Inter-chromatid Axis and Is Evicted along with Shugoshin by SET during Mitosis.

Science.gov (United States)

Krishnan, Swathi; Smits, Arne H; Vermeulen, Michiel; Reinberg, Danny

2017-08-17

Precise control of sister chromatid separation during mitosis is pivotal to maintaining genomic integrity. Yet, the regulatory mechanisms involved are not well understood. Remarkably, we discovered that linker histone H1 phosphorylated at S/T18 decorated the inter-chromatid axial DNA on mitotic chromosomes. Sister chromatid resolution during mitosis required the eviction of such H1S/T18ph by the chaperone SET, with this process being independent of and most likely downstream of arm-cohesin dissociation. SET also directed the disassembly of Shugoshins in a polo-like kinase 1-augmented manner, aiding centromere resolution. SET ablation compromised mitotic fidelity as evidenced by unresolved sister chromatids with marked accumulation of H1S/T18ph and centromeric Shugoshin. Thus, chaperone-assisted eviction of linker histones and Shugoshins is a fundamental step in mammalian mitotic progression. Our findings also elucidate the functional implications of the decades-old observation of mitotic linker histone phosphorylation, serving as a paradigm to explore the role of linker histones in bio-signaling processes. Copyright © 2017 Elsevier Inc. All rights reserved.

Self-organization of intracellular gradients during mitosis

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Fuller Brian G

2010-01-01

Full Text Available Abstract Gradients are used in a number of biological systems to transmit spatial information over a range of distances. The best studied are morphogen gradients where information is transmitted over many cell lengths. Smaller mitotic gradients reflect the need to organize several distinct events along the length of the mitotic spindle. The intracellular gradients that characterize mitosis are emerging as important regulatory paradigms. Intracellular gradients utilize intrinsic auto-regulatory feedback loops and diffusion to establish stable regions of activity within the mitotic cytosol. We review three recently described intracellular mitotic gradients. The Ran GTP gradient with its elaborate cascade of nuclear transport receptors and cargoes is the best characterized, yet the dynamics underlying the robust gradient of Ran-GTP have received little attention. Gradients of phosphorylation have been observed on Aurora B kinase substrates both before and after anaphase onset. In both instances the phosphorylation gradient appears to result from a soluble gradient of Aurora B kinase activity. Regulatory properties that support gradient formation are highlighted. Intracellular activity gradients that regulate localized mitotic events bare several hallmarks of self-organizing biologic systems that designate spatial information during pattern formation. Intracellular pattern formation represents a new paradigm in mitotic regulation.

Cdk1 Phosphorylates Drosophila Sas-4 to Recruit Polo to Daughter Centrioles and Convert Them to Centrosomes.

Science.gov (United States)

Novak, Zsofia A; Wainman, Alan; Gartenmann, Lisa; Raff, Jordan W

2016-06-20

Centrosomes and cilia are organized by a centriole pair comprising an older mother and a younger daughter. Centriole numbers are tightly regulated, and daughter centrioles (which assemble in S phase) cannot themselves duplicate or organize centrosomes until they have passed through mitosis. It is unclear how this mitotic "centriole conversion" is regulated, but it requires Plk1/Polo kinase. Here we show that in flies, Cdk1 phosphorylates the conserved centriole protein Sas-4 during mitosis. This creates a Polo-docking site that helps recruit Polo to daughter centrioles and is required for the subsequent recruitment of Asterless (Asl), a protein essential for centriole duplication and mitotic centrosome assembly. Point mutations in Sas-4 that prevent Cdk1 phosphorylation or Polo docking do not block centriole disengagement during mitosis, but block efficient centriole conversion and lead to embryonic lethality. These observations can explain why daughter centrioles have to pass through mitosis before they can duplicate and organize a centrosome. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

Nonperiodic activity of the human anaphase-promoting complex-Cdh1 ubiquitin ligase results in continuous DNA synthesis uncoupled from mitosis

DEFF Research Database (Denmark)

Lukas, C; Kramer, E R; Peters, J M

2000-01-01

, in Saccharomyces cerevisiae and Drosophila spp., triggers exit from mitosis and during G(1) prevents unscheduled DNA replication. In this study we investigated the importance of periodic oscillation of the APC-Cdh1 activity for the cell cycle progression in human cells. We show that conditional interference...

The multiple roles of Bub1 in chromosome segregation during mitosis and meiosis

Energy Technology Data Exchange (ETDEWEB)

Marchetti, Francesco; Venkatachalam, Sundaresan

2009-06-19

Aneuploidy, any deviation from an exact multiple of the haploid number of chromosomes, is a common occurrence in cancer and represents the most frequent chromosomal disorder in newborns. Eukaryotes have evolved mechanisms to assure the fidelity of chromosome segregation during cell division that include a multiplicity of checks and controls. One of the main cell division control mechanisms is the spindle assembly checkpoint (SAC) that monitors the proper attachment of chromosomes to spindle fibers and prevents anaphase until all kinetochores are properly attached. The mammalian SAC is composed by at least 14 evolutionary-conserved proteins that work in a coordinated fashion to monitor the establishment of amphitelic attachment of all chromosomes before allowing cell division to occur. Among the SAC proteins, the budding uninhibited by benzimidazole protein 1 (Bub1), is a highly conserved protein of prominent importance for the proper functioning of the SAC. Studies have revealed many roles for Bub1 in both mitosis and meiosis, including the localization of other SAC proteins to the kinetochore, SAC signaling, metaphase congression and the protection of the sister chromatid cohesion. Recent data show striking sex specific differences in the response to alterations in Bub1 activity. Proper Bub1 functioning is particularly important during oogenesis in preventing the generation of aneuploid gametes that can have detrimental effects on the health status of the fetus and the newborn. These data suggest that Bub1 is a master regulator of SAC and chromosomal segregation in both mitosis and meiosis. Elucidating its many essential functions in regulating proper chromosome segregation can have important consequences for preventing tumorigenesis and developmental abnormalities.

Atypical growth, abonormal mitosis and polyploidy induced by ethyl-mercury-chloride

Energy Technology Data Exchange (ETDEWEB)

Kostoff, D

1940-01-01

Experiments were performed to study the effect of ethyl mercury chloride upon the atypical growths of plants. Seeds of peas, flax, rye, and wheat were treated with 2% ethyl mercury chloride. The fungicide suppressed the development of the seedlings. Cytological studies revealed that the fungicide had also significantly affected the procedure of mitosis in most of the treated seedlings. The chromosomes did not become arranged into a proper equatorial plate when the nucleus membrane and the nucleolei disappeared, but occupied a position similar to that which they had during the prophase. The chromosomes split, then the centromeres divided so that from each one chromosome, two chromosomes originated, situated side by side without polar separation, chiefly due to the absence of normal achromatic figures. Thus, chromosome division without cell division takes place.

Adhesion of axolemmal fragments to Schwann cells: a signal- and target-specific process closely linked to axolemmal induction of Schwann cell mitosis

International Nuclear Information System (INIS)

Sobue, G.; Pleasure, D.

1985-01-01

Radioiodinated rat CNS axolemmal fragments adhered to cultured rat Schwann cells by a time-, temperature-, and concentration-dependent process independent of extracellular ionized calcium. Adhesion showed target and signal specificity; axolemmal fragments adhered to endoneurial or dermal fibroblasts to a much lesser extent than to Schwann cells, and plasma membrane fragments from skeletal muscle, erythrocytes, or PNS myelin adhered to Schwann cells to a lesser extent than did axolemmal fragments. Brief trypsinization removed 94 to 97% of bound radioactivity from Schwann cells previously incubated with 125 I-axolemmal fragments for up to 24 hr, indicating that adhesion was largely a surface phenomenon rather than the result of rapid internalization of axolemmal fragments by the Schwann cells. When adhesion was compared to the axolemmal mitogenic response of Schwann cells, the concentration of axolemmal fragments yielding half-maximal adhesion was the same as the concentration producing half-maximal stimulation of Schwann cell mitosis. Trypsin digestion, homogenization, or heating of axolemmal fragments before application to cultured Schwann cells diminished adhesion and axolemmal fragment-induced stimulation of Schwann cell mitosis in a parallel fashion. Whereas adhesion of axolemmal fragments to the surfaces of the cultured Schwann cells reached completion within 4 hr in this assay system, induction of Schwann cell mitosis by the fragments required contact with Schwann cells for a minimum of 6 to 8 hr and reached a maximum when the axolemmal fragments had adhered to the Schwann cells for 24 hr or more

Expression of progesterone receptor membrane component-2 within the immature rat ovary and its role in regulating mitosis and apoptosis of spontaneously immortalized granulosa cells.

Science.gov (United States)

Griffin, Daniel; Liu, Xiufang; Pru, Cindy; Pru, James K; Peluso, John J

2014-08-01

Progesterone receptor membrane component 2 (Pgrmc2) mRNA was detected in the immature rat ovary. By 48 h after eCG, Pgrmc2 mRNA levels decreased by 40% and were maintained at 48 h post-hCG. Immunohistochemical studies detected PGRMC2 in oocytes and ovarian surface epithelial, interstitial, thecal, granulosa, and luteal cells. PGRMC2 was also present in spontaneously immortalized granulosa cells, localizing to the cytoplasm of interphase cells and apparently to the mitotic spindle of cells in metaphase. Interestingly, PGRMC2 levels appeared to decrease during the G1 stage of the cell cycle. Moreover, overexpression of PGRMC2 suppressed entry into the cell cycle, possibly by binding the p58 form of cyclin dependent kinase 11b. Conversely, Pgrmc2 small interfering RNA (siRNA) treatment increased the percentage of cells in G1 and M stage but did not increase the number of cells, which was likely due to an increase in apoptosis. Depleting PGRMC2 did not inhibit cellular (3)H-progesterone binding, but attenuated the ability of progesterone to suppress mitosis and apoptosis. Taken together these studies suggest that PGRMC2 affects granulosa cell mitosis by acting at two specific stages of the cell cycle. First, PGRMC2 regulates the progression from the G0 into the G1 stage of the cell cycle. Second, PGRMC2 appears to localize to the mitotic spindle, where it likely promotes the final stages of mitosis. Finally, siRNA knockdown studies indicate that PGRMC2 is required for progesterone to slow the rate of granulosa cell mitosis and apoptosis. These findings support a role for PGRMC2 in ovarian follicle development. © 2014 by the Society for the Study of Reproduction, Inc.

An integrated overview of spatiotemporal organization and regulation in mitosis in terms of the proteins in the functional supercomplexes

Directory of Open Access Journals (Sweden)

Yueyuan eZheng

2014-10-01

Full Text Available Eukaryotic cells may divide via the critical cellular process of cell division/mitosis, resulting in two daughter cells with the same genetic information. A large number of dedicated proteins are involved in this process and spatiotemporally assembled into three distinct super-complex structures/organelles, including the centrosome/spindle pole body, kinetochore/centromere and cleavage furrow/midbody/bud neck, so as to precisely modulate the cell division/mitosis events of chromosome alignment, chromosome segregation and cytokinesis in an orderly fashion. In recent years, many efforts have been made to identify the protein components and architecture of these subcellular organelles, aiming to uncover the organelle assembly pathways, determine the molecular mechanisms underlying the organelle functions, and thereby provide new therapeutic strategies for a variety of diseases. However, the organelles are highly dynamic structures, making it difficult to identify the entire components. Here, we review the current knowledge of the identified protein components governing the organization and functioning of organelles, especially in human and yeast cells, and discuss the multi-localized protein components mediating the communication between organelles during cell division.

The FANC pathway and BLM collaborate during mitosis to prevent micro-nucleation and chromosome abnormalities.

Science.gov (United States)

Naim, Valeria; Rosselli, Filippo

2009-06-01

Loss-of-function of caretaker genes characterizes a group of cancer predisposition diseases that feature cellular hypersensitivity to DNA damage and chromosome fragility; this group includes Fanconi anaemia and Bloom syndrome. The products of the 13 FANC genes (mutated in Fanconi anaemia), which constitute the 'FANC' pathway, and BLM (the RecQ helicase mutated in Bloom syndrome) are thought to collaborate during the S phase of the cell cycle, preventing chromosome instability. Recently, BLM has been implicated in the completion of sister chromatid separation during mitosis, a complex process in which precise regulation and execution is crucial to preserve genomic stability. Here we show for the first time a role for the FANC pathway in chromosome segregation during mitotic cell division. FANCD2, a key component of the pathway, localizes to discrete spots on mitotic chromosomes. FANCD2 chromosomal localization is responsive to replicative stress and specifically targets aphidicolin (APH)-induced chromatid gaps and breaks. Our data indicate that the FANC pathway is involved in rescuing abnormal anaphase and telophase (ana-telophase) cells, limiting aneuploidy and reducing chromosome instability in daughter cells. We further address a cooperative role for the FANC pathway and BLM in preventing micronucleation, through FANC-dependent targeting of BLM to non-centromeric abnormal structures induced by replicative stress. We reveal new crosstalk between FANC and BLM proteins, extending their interaction beyond the S-phase rescue of damaged DNA to the safeguarding of chromosome stability during mitosis.

The phosphorylation-dependent regulation of nuclear SREBP1 during mitosis links lipid metabolism and cell growth

Science.gov (United States)

Bengoechea-Alonso, Maria Teresa; Ericsson, Johan

2016-01-01

ABSTRACT The SREBP transcription factors are major regulators of lipid metabolism. Disturbances in lipid metabolism are at the core of several health issues facing modern society, including cardiovascular disease, obesity and diabetes. In addition, the role of lipid metabolism in cancer cell growth is receiving increased attention. Transcriptionally active SREBP molecules are unstable and rapidly degraded in a phosphorylation-dependent manner by Fbw7, a ubiquitin ligase that targets several cell cycle regulatory proteins for degradation. We have previously demonstrated that active SREBP1 is stabilized during mitosis. We have now delineated the mechanisms involved in the stabilization of SREBP1 in mitotic cells. This process is initiated by the phosphorylation of a specific serine residue in nuclear SREBP1 by the mitotic kinase Cdk1. The phosphorylation of this residue creates a docking site for a separate mitotic kinase, Plk1. Plk1 interacts with nuclear SREBP1 in mitotic cells and phosphorylates a number of residues in the C-terminal domain of the protein, including a threonine residue in close proximity of the Fbw7 docking site in SREBP1. The phosphorylation of these residues by Plk1 blocks the interaction between SREBP1 and Fbw7 and attenuates the Fbw7-dependent degradation of nuclear SREBP1 during cell division. Inactivation of SREBP1 results in a mitotic defect, suggesting that SREBP1 could regulate cell division. We propose that the mitotic phosphorylation and stabilization of nuclear SREBP1 during cell division provides a link between lipid metabolism and cell proliferation. Thus, the current study provides additional support for the emerging hypothesis that SREBP-dependent lipid metabolism may be important for cell growth. PMID:27579997

Model-based investigation of the circadian clock and cell cycle coupling in mouse embryonic fibroblasts: Prediction of RevErb-α up-regulation during mitosis.

Science.gov (United States)

Traynard, Pauline; Feillet, Céline; Soliman, Sylvain; Delaunay, Franck; Fages, François

2016-11-01

Experimental observations have put in evidence autonomous self-sustained circadian oscillators in most mammalian cells, and proved the existence of molecular links between the circadian clock and the cell cycle. Some mathematical models have also been built to assess conditions of control of the cell cycle by the circadian clock. However, recent studies in individual NIH3T3 fibroblasts have shown an unexpected acceleration of the circadian clock together with the cell cycle when the culture medium is enriched with growth factors, and the absence of such acceleration in confluent cells. In order to explain these observations, we study a possible entrainment of the circadian clock by the cell cycle through a regulation of clock genes around the mitosis phase. We develop a computational model and a formal specification of the observed behavior to investigate the conditions of entrainment in period and phase. We show that either the selective activation of RevErb-α or the selective inhibition of Bmal1 transcription during the mitosis phase, allow us to fit the experimental data on both period and phase, while a uniform inhibition of transcription during mitosis seems incompatible with the phase data. We conclude on the arguments favoring the RevErb-α up-regulation hypothesis and on some further predictions of the model. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

p-TSA-promoted syntheses of 5H-benzo[h] thiazolo[2,3-b]quinazoline and indeno[1,2-d] thiazolo[3,2-a]pyrimidine analogs: molecular modeling and in vitro antitumor activity against hepatocellular carcinoma.

Science.gov (United States)

Keshari, Amit K; Singh, Ashok K; Raj, Vinit; Rai, Amit; Trivedi, Prakruti; Ghosh, Balaram; Kumar, Umesh; Rawat, Atul; Kumar, Dinesh; Saha, Sudipta

2017-01-01

In our efforts to address the rising incidence of hepatocellular carcinoma (HCC), we have made a commitment to the synthesis of novel molecules to combat Hep-G2 cells. A facile and highly efficient one-pot, multicomponent reaction has been successfully devised utilizing a p -toluenesulfonic acid ( p -TSA)-catalyzed domino Knoevenagel/Michael/intramolecular cyclization approach for the synthesis of novel 5H-benzo[h]thiazolo[2,3-b]quinazoline and indeno[1,2-d] thiazolo[3,2-a]pyrimidine analogs bearing a bridgehead nitrogen atom. This domino protocol constructed one new ring by the concomitant formation of multiple bonds (C-C, C-N, and C=N) involving multiple steps without the use of any metal catalysts in one-pot, with all reactants effi-ciently exploited. All the newly synthesized compounds were authenticated by means of Fourier transform infrared spectroscopy, liquid chromatography-mass spectrometry, proton nuclear magnetic resonance spectroscopy, and carbon-13 nuclear magnetic resonance spectroscopy, together with elemental analysis, and their antitumor activity was evaluated in vitro on a Hep-G2 human cancer cell line by sulforhodamine B assay. Computational molecular modeling studies were carried out on cancer-related targets, including interleukin-2, interleukin-6, Caspase-3, and Caspase-8. Two compounds (4A and 6A) showed growth inhibitory activity comparable to the positive control Adriamycin, with growth inhibition of 50% <10 μg/mL. The results of the comprehensive structure-activity relationship study confirmed the assumption that two or more electronegative groups on the phenyl ring attached to the thiazolo[2,3-b]quinazoline system showed the optimum effect. The in silico simulations suggested crucial hydrogen bond and π-π stacking interactions, with a good ADMET (absorption, distribution, metabolism, excretion, and toxicity) profile and molecular dynamics, in order to explore the molecular targets of HCC which were in complete agreement with the in

Water droplet excess free energy determined by cluster mitosis using guided molecular dynamics

Energy Technology Data Exchange (ETDEWEB)

Lau, Gabriel V.; Müller, Erich A.; Jackson, George [Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Hunt, Patricia A. [Department of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Ford, Ian J. [Department of Physics and Astronomy and London Centre for Nanotechnology, University College London, Gower Street, London WC1E 6BT (United Kingdom)

2015-12-28

Atmospheric aerosols play a vital role in affecting climate by influencing the properties and lifetimes of clouds and precipitation. Understanding the underlying microscopic mechanisms involved in the nucleation of aerosol droplets from the vapour phase is therefore of great interest. One key thermodynamic quantity in nucleation is the excess free energy of cluster formation relative to that of the saturated vapour. In our current study, the excess free energy is extracted for clusters of pure water modelled with the TIP4P/2005 intermolecular potential using a method based on nonequilibrium molecular dynamics and the Jarzynski relation. The change in free energy associated with the “mitosis” or division of a cluster of N water molecules into two N/2 sub-clusters is evaluated. This methodology is an extension of the disassembly procedure used recently to calculate the excess free energy of argon clusters [H. Y. Tang and I. J. Ford, Phys. Rev. E 91, 023308 (2015)]. Our findings are compared to the corresponding excess free energies obtained from classical nucleation theory (CNT) as well as internally consistent classical theory (ICCT). The values of the excess free energy that we obtain with the mitosis method are consistent with CNT for large cluster sizes but for the smallest clusters, the results tend towards ICCT; for intermediate sized clusters, we obtain values between the ICCT and CNT predictions. Furthermore, the curvature-dependent surface tension which can be obtained by regarding the clusters as spherical droplets of bulk density is found to be a monotonically increasing function of cluster size for the studied range. The data are compared to other values reported in the literature, agreeing qualitatively with some but disagreeing with the values determined by Joswiak et al. [J. Phys. Chem. Lett. 4, 4267 (2013)] using a biased mitosis approach; an assessment of the differences is the main motivation for our current study.

MLL/WDR5 Complex Regulates Kif2A Localization to Ensure Chromosome Congression and Proper Spindle Assembly during Mitosis.

Science.gov (United States)

Ali, Aamir; Veeranki, Sailaja Naga; Chinchole, Akash; Tyagi, Shweta

2017-06-19

Mixed-lineage leukemia (MLL), along with multisubunit (WDR5, RbBP5, ASH2L, and DPY30) complex catalyzes the trimethylation of H3K4, leading to gene activation. Here, we characterize a chromatin-independent role for MLL during mitosis. MLL and WDR5 localize to the mitotic spindle apparatus, and loss of function of MLL complex by RNAi results in defects in chromosome congression and compromised spindle formation. We report interaction of MLL complex with several kinesin and dynein motors. We further show that the MLL complex associates with Kif2A, a member of the Kinesin-13 family of microtubule depolymerase, and regulates the spindle localization of Kif2A during mitosis. We have identified a conserved WDR5 interaction (Win) motif, so far unique to the MLL family, in Kif2A. The Win motif of Kif2A engages in direct interactions with WDR5 for its spindle localization. Our findings highlight a non-canonical mitotic function of MLL complex, which may have a direct impact on chromosomal stability, frequently compromised in cancer. Copyright © 2017 Elsevier Inc. All rights reserved.

The roles of BDNF, pCREB and Wnt3a in the latent period preceding activation of progenitor cell mitosis in the adult dentate gyrus by fluoxetine.

Directory of Open Access Journals (Sweden)

Scarlett B Pinnock

2010-10-01

Full Text Available The formation of new neurons continues into adult life in the dentate gyrus of the rat hippocampus, as in many other species. Neurogenesis itself turns out to be highly labile, and is regulated by a number of factors. One of these is the serotoninergic system: treatment with drugs (such as the SSRI fluoxetine markedly stimulates mitosis in the progenitor cells of the dentate gyrus. But this process has one remarkable feature: it takes at least 14 days of continuous treatment to be effective. This is despite the fact that the pharmacological action of fluoxetine occurs within an hour or so of first administration. This paper explores the role of BDNF in this process, using the effect of a Trk antagonist (K252a on the labelling of progenitor cells with the mitosis marker Ki67 and the associated expression of pCREB and Wnt3a. These experiments show that (i Fluoxetine increased Ki67 counts, as well as pCREB and Wnt3a expression in the dentate gyrus. The action of fluoxetine on the progenitor cells and on pCREB (but not Wnt3a depends upon Trk receptor activation, since it was prevented by icv infusion of K252a. (ii These receptors are required for both the first 7 days of fluoxetine action, during which no apparent change in progenitor mitosis occurs, as well as the second 7 days. Increased pCREB was always associated with progenitor cell mitosis, but Wnt3a expression may be necessary but not sufficient for increased progenitor cell proliferation. These results shed new light on the action of fluoxetine on neurogenesis in the adult dentate gyrus, and have both clinical and experimental interest.

Crystal structure of 4-methylsulfanyl-2-phenylquinazoline

Directory of Open Access Journals (Sweden)

Mohammed B. Alshammari

2014-08-01

Full Text Available In the title compound, C15H12N2S, the methylthioquinazoline group is planar with the methyl C displaced by only 0.116 (3 Å from the plane of the quinazoline moiety. The dihedral angle between the phenyl ring and the quinazoline ring system is 13.95 (5°. In the crystal, each molecule is linked by π–π stacking between to two adjacent inversion-related molecules. On one side, the inverted quinazoline groups interact with a centroid–centroid distance of 3.7105 (9 Å. On the other side, the quinazoline group interacts with the pyrimidine and phenyl rings of the second neighbour with centroid–centroid distances of 3.5287 (8 and 3.8601 (9 Å, respectively.

Cdk1-Cyclin B1-mediated Phosphorylation of Tumor-associated Microtubule-associated Protein/Cytoskeleton-associated Protein 2 in Mitosis*

OpenAIRE

Uk Hong, Kyung; Kim, Hyun-Jun; Kim, Hyo-Sil; Seong, Yeon-Sun; Hong, Kyeong-Man; Bae, Chang-Dae; Park, Joobae

2009-01-01

During mitosis, establishment of structurally and functionally sound bipolar spindles is necessary for maintaining the fidelity of chromosome segregation. Tumor-associated microtubule-associated protein (TMAP), also known as cytoskeleton-associated protein 2 (CKAP2), is a mitotic spindle-associated protein whose level is frequently up-regulated in various malignancies. Previous reports have suggested that TMAP is a potential regulator of mitotic spindle assembly and dynamics and that it is re...

Analysis of Block OMP using Block RIP

OpenAIRE

Wang, Jun; Li, Gang; Zhang, Hao; Wang, Xiqin

2011-01-01

Orthogonal matching pursuit (OMP) is a canonical greedy algorithm for sparse signal reconstruction. When the signal of interest is block sparse, i.e., it has nonzero coefficients occurring in clusters, the block version of OMP algorithm (i.e., Block OMP) outperforms the conventional OMP. In this paper, we demonstrate that a new notion of block restricted isometry property (Block RIP), which is less stringent than standard restricted isometry property (RIP), can be used for a very straightforw...

Structural Exploration of Quinazolin-4(3H)-ones as Anticonvulsants: Rational Design, Synthesis, Pharmacological Evaluation, and Molecular Docking Studies.

Science.gov (United States)

Ugale, Vinod G; Bari, Sanjay B

2016-11-01

Anticonvulsants effective against multiple seizures are of wide interest as antiepileptic drugs, especially if active against pharmaco-resistant seizures. Herein, we synthesized 16 different, rationally designed 2-((6,7-dimethoxy-4-oxo-2-phenylquinazolin-3(4H)-yl)amino)-N-(substituted phenyl)acetamides and screened for anticonvulsant activities through in vivo experiments. Compound 4d emerged as prototype with excellent anti-seizure action in mice against electroshock, chemically induced and pharmaco-resistant 6-Hz seizure models with no symptoms of neurotoxicity and hepatotoxicity (ED 50  = 23.5 mg/kg, MES, mice, i.p.; ED 50  = 32.6 mg/kg, scPTZ, mice, i.p.; ED 50  = 45.2 mg/kg, 6-Hz, mice, i.p.; TD 50  = 325.9 mg/kg, mice, i.p.). In addition, investigation of compound 4l in mice for its pharmacological profile proved it as safer anticonvulsant, devoid of the side effects such as motor dysfunction and hepatotoxicity of classical antiepileptic drugs (ED 50  = 26.1 mg/kg, MES, mice, i.p.; ED 50  = 79.4 mg/kg, scPTZ, mice, i.p.; TD 50  = 361.2 mg/kg, mice, i.p.). We also predicted physiochemical and pharmacokinetic properties of structurally optimized quinazolin-4(3H)-ones by a computational protocol. A combination of in vivo anticonvulsant profile, ex vivo toxicity, and in silico studies suggested that the synthesized compounds may be useful as broad-spectrum anti-seizure drug candidates with favorable pharmacokinetic parameters. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

31 CFR 595.301 - Blocked account; blocked property.

Science.gov (United States)

2010-07-01

... (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY TERRORISM SANCTIONS REGULATIONS General Definitions § 595.301 Blocked account; blocked property. The terms blocked account and blocked...

The duration of G1, S, G2, and mitosis at four different temperatures in Zea mays L. as measured with 3H-thymidine

International Nuclear Information System (INIS)

Verma, R.S.

1980-01-01

The effect of different temperatures on the duration of nuclear cycle in Zea mays (single cross hybrid 'Seneca 60') root meristem cells, was studied with autoradiographic techniques and it was shown that all component phases of the nuclear cycle are shortened by an increase in temperature from 20 to 35 0 C. The durations of total nuclear cycle at 20, 25, 30, and 35 0 C were 16.5, 9.9, 7.0, and 4.4 hours respectively while the durations of mitosis were 2.68, 1.10, 0.83, and 0.43 hours respectively. 85 - 90 percent of the nuclear cycle is required for interphase, while the remaining 10 - 15 percent of the cycle is occupied by mitosis. The mean mitotic indices at 20, 25, 30, and 35 0 C were 9.8, 9.1, 5.3, and 4.9 percent respectively. (author)

Role of endothelial permeability hotspots and endothelial mitosis in determining age-related patterns of macromolecule uptake by the rabbit aortic wall near branch points.

Science.gov (United States)

Chooi, K Yean; Comerford, Andrew; Cremers, Stephanie J; Weinberg, Peter D

2016-07-01

Transport of macromolecules between plasma and the arterial wall plays a key role in atherogenesis. Scattered hotspots of elevated endothelial permeability to macromolecules occur in the aorta; a fraction of them are associated with dividing cells. Hotspots occur particularly frequently downstream of branch points, where lesions develop in young rabbits and children. However, the pattern of lesions varies with age, and can be explained by similar variation in the pattern of macromolecule uptake. We investigated whether patterns of hotspots and mitosis also change with age. Evans' Blue dye-labeled albumin was injected intravenously into immature or mature rabbits and its subsequent distribution in the aortic wall around intercostal branch ostia examined by confocal microscopy and automated image analysis. Mitosis was detected by immunofluorescence after adding 5-bromo-2-deoxiuridine to drinking water. Hotspots were most frequent downstream of branches in immature rabbits, but a novel distribution was observed in mature rabbits. Neither pattern was explained by mitosis. Hotspot uptake correlated spatially with the much greater non-hotspot uptake (p hotspots were considered. The pattern of hotspots changes with age. The data are consistent with there being a continuum of local permeabilities rather than two distinct mechanisms. The distribution of the dye, which binds to elastin and collagen, was similar to that of non-binding tracers and to lesions apart from a paucity at the lateral margins of branches that can be explained by lower levels of fibrous proteins in those regions. Copyright © 2016. Published by Elsevier Ireland Ltd.

Nerve Blocks

Science.gov (United States)

... News Physician Resources Professions Site Index A-Z Nerve Blocks A nerve block is an injection to ... the limitations of Nerve Block? What is a Nerve Block? A nerve block is an anesthetic and/ ...

Liver fatty acid binding protein is the mitosis-associated polypeptide target of a carcinogen in rat hepatocytes

International Nuclear Information System (INIS)

Bassuk, J.A.; Tsichlis, P.N.; Sorof, S.

1987-01-01

Hepatocytes in normal rat liver were found previously to contain a cytoplasmic 14,000-dalton polypeptide (p14) that is associated with mitosis and is the principal early covalent target of activated metabolites of the carcinogen N-2-fluorenylacetamide (2-acetylaminofluorene). The level of immunohistochemically detected p14 was low when growth activity of hepatocytes was low, was markedly elevated during mitosis in normal and regenerating livers, but was very high throughout interphase during proliferation of hyperplastic and malignant hepatocytes induced in rat liver by a carcinogen (N-2-fluorenylacetamide or 3'-methyl-4-dimethylaminoazobenzene). The authors report here that p14 is the liver fatty acid binding protein. The nucleotide sequence of p14 cDNA clones, isolated by screening a rat liver cDNA library in bacteriophage λgt11 using p14 antiserum, was completely identical to part of the sequence reported for liver fatty acid binding protein. Furthermore, the two proteins shared the following properties: size of mRNA, amino acid composition, molecular size according to NaDodSO 4 gel electrophoresis, and electrophoretic mobilities in a Triton X-100/acetic acid/urea gel. The two polypeptides bound oleic acid similarly. Finally, identical elevations of cytoplasmic immunostain were detected specifically in mitotic hepatocytes with either antiserum. The collected findings are suggestive that liver fatty acid binding protein may carry ligands that promote hepatocyte division and may transport certain activated chemical carcinogens

Testing block subdivision algorithms on block designs

Science.gov (United States)

Wiseman, Natalie; Patterson, Zachary

2016-01-01

Integrated land use-transportation models predict future transportation demand taking into account how households and firms arrange themselves partly as a function of the transportation system. Recent integrated models require parcels as inputs and produce household and employment predictions at the parcel scale. Block subdivision algorithms automatically generate parcel patterns within blocks. Evaluating block subdivision algorithms is done by way of generating parcels and comparing them to those in a parcel database. Three block subdivision algorithms are evaluated on how closely they reproduce parcels of different block types found in a parcel database from Montreal, Canada. While the authors who developed each of the algorithms have evaluated them, they have used their own metrics and block types to evaluate their own algorithms. This makes it difficult to compare their strengths and weaknesses. The contribution of this paper is in resolving this difficulty with the aim of finding a better algorithm suited to subdividing each block type. The proposed hypothesis is that given the different approaches that block subdivision algorithms take, it's likely that different algorithms are better adapted to subdividing different block types. To test this, a standardized block type classification is used that consists of mutually exclusive and comprehensive categories. A statistical method is used for finding a better algorithm and the probability it will perform well for a given block type. Results suggest the oriented bounding box algorithm performs better for warped non-uniform sites, as well as gridiron and fragmented uniform sites. It also produces more similar parcel areas and widths. The Generalized Parcel Divider 1 algorithm performs better for gridiron non-uniform sites. The Straight Skeleton algorithm performs better for loop and lollipop networks as well as fragmented non-uniform and warped uniform sites. It also produces more similar parcel shapes and patterns.

Origin of the cell nucleus, mitosis and sex: roles of intracellular coevolution.

Science.gov (United States)

Cavalier-Smith, Thomas

2010-02-04

The transition from prokaryotes to eukaryotes was the most radical change in cell organisation since life began, with the largest ever burst of gene duplication and novelty. According to the coevolutionary theory of eukaryote origins, the fundamental innovations were the concerted origins of the endomembrane system and cytoskeleton, subsequently recruited to form the cell nucleus and coevolving mitotic apparatus, with numerous genetic eukaryotic novelties inevitable consequences of this compartmentation and novel DNA segregation mechanism. Physical and mutational mechanisms of origin of the nucleus are seldom considered beyond the long-standing assumption that it involved wrapping pre-existing endomembranes around chromatin. Discussions on the origin of sex typically overlook its association with protozoan entry into dormant walled cysts and the likely simultaneous coevolutionary, not sequential, origin of mitosis and meiosis. I elucidate nuclear and mitotic coevolution, explaining the origins of dicer and small centromeric RNAs for positionally controlling centromeric heterochromatin, and how 27 major features of the cell nucleus evolved in four logical stages, making both mechanisms and selective advantages explicit: two initial stages (origin of 30 nm chromatin fibres, enabling DNA compaction; and firmer attachment of endomembranes to heterochromatin) protected DNA and nascent RNA from shearing by novel molecular motors mediating vesicle transport, division, and cytoplasmic motility. Then octagonal nuclear pore complexes (NPCs) arguably evolved from COPII coated vesicle proteins trapped in clumps by Ran GTPase-mediated cisternal fusion that generated the fenestrated nuclear envelope, preventing lethal complete cisternal fusion, and allowing passive protein and RNA exchange. Finally, plugging NPC lumens by an FG-nucleoporin meshwork and adopting karyopherins for nucleocytoplasmic exchange conferred compartmentation advantages. These successive changes took place

Cellular Tug-of-War: Forces at Work and DNA Stretching in Mitosis

Science.gov (United States)

Griffin, Brian; Kilfoil, Maria L.

2013-03-01

In the microscopic world of the cell dominated by thermal noise, a cell must be able to successfully segregate its DNA with high fidelity in order to pass its genetic information on to its progeny. In this process of mitosis in eukaryotes, driving forces act on the cytoskeleton-based architecture called the mitotic spindle to promote this division. Our preliminary data demonstrates that the dynamics of this process in yeast cells is universal. Moreover, the dynamics suggest an increasing load as the chromosomes are pulled apart. To investigate this, we use three-dimensional imaging to track the dynamics of the poles of this architecture and the points of attachment to chromosomes simultaneously and with high spatial resolution. We analyze the relative motions of chromosomes as they are organized before segregation and as they are pulled apart, using this data to investigate the force-response behavior of this cytoskeleton-chromosome polymer system.

Non-coding RNAs enter mitosis: functions, conservation and implications

Directory of Open Access Journals (Sweden)

Kai Toshie

2011-02-01

Full Text Available Abstract Nuage (or commonly known as chromatoid body in mammals is a conserved germline-specific organelle that has been linked to the Piwi-interacting RNA (piRNA pathway. piRNAs are a class of gonadal-specific RNAs that are ~23-29 nucleotides in length and protect genome stability by repressing the expression of deleterious retrotransposons. More recent studies in Drosophila have implicated the piRNA pathway in other functions including canalization of embryonic development, regulation of maternal gene expression and telomere protection. We have recently shown that Vasa (known as Mouse Vasa Homolog in mouse, a nuage component, plays a mitotic role in promoting chromosome condensation and segregation by facilitating robust chromosomal localization of condensin I in the Drosophila germline. Vasa functions together with Aubergine (a PIWI family protein and Spindle-E/mouse TDRD-9, two other nuage components that are involved in the piRNA pathway, therefore providing a link between the piRNA pathway and mitotic chromosome condensation. Here, we propose and discuss possible models for the role of Vasa and the piRNA pathway during mitosis. We also highlight relevant studies implicating mitotic roles for RNAs and/or nuage in other model systems and their implications for cancer development.

The effect of oleander glycosides on the germination of pollen grains and the mitosis of the generative nucleus in Tradescantia bracteata Small and Allium cepa L.

Directory of Open Access Journals (Sweden)

J. A. Tarkowska

2015-01-01

Full Text Available The effect of water solution of a mixture of glycosides from oleander (Nerium oleander L. on the germination of pollen grains and on the mitosis of the generative nucleus in Tradescantia bracteata Small and Allium cepa L. has been studied. An inhibition of the germination and of the growth of pollen tubes was observed, proportionally to the concentration of glycosides. The pollen grains of A. cepa are more sensitive. The disturbances in mitosis lead to the formation of two or more uneven-sized doughter nuclei, or to the formation of restitution nuclei. These anomalies are more numerous in T. bracteata. From these results d t appears that pollen grains of A. cepa are characterized by a generally high physiological sensitivity and a small mitotic sensitivity, wheras for T. bracteata the opposite is true.

Precise and economic FIB/SEM for CLEM: with 2 nm voxels through mitosis.

Science.gov (United States)

Luckner, Manja; Wanner, Gerhard

2018-05-23

A portfolio is presented documenting economic, high-resolution correlative focused ion beam scanning electron microscopy (FIB/SEM) in routine, comprising: (i) the use of custom-labeled slides and coverslips, (ii) embedding of cells in thin, or ultra-thin resin layers for correlative light and electron microscopy (CLEM) and (iii) the claim to reach the highest resolution possible with FIB/SEM in xyz. Regions of interest (ROIs) defined in light microscope (LM), can be relocated quickly and precisely in SEM. As proof of principle, HeLa cells were investigated in 3D context at all stages of the cell cycle, documenting ultrastructural changes during mitosis: nuclear envelope breakdown and reassembly, Golgi degradation and reconstitution and the formation of the midzone and midbody.

Lamin A reassembly at the end of mitosis is regulated by its SUMO-interacting motif

Energy Technology Data Exchange (ETDEWEB)

Moriuchi, Takanobu; Kuroda, Masaki; Kusumoto, Fumiya; Osumi, Takashi; Hirose, Fumiko, E-mail: fhirose@sci.u-hyogo.ac.jp

2016-03-01

Modification of proteins with small ubiquitin-related modifier (SUMO; SUMOylation) is involved in the regulation of various biological processes. Recent studies have demonstrated that noncovalent associations between SUMOylated proteins and co-operative proteins containing SUMO-interacting motifs (SIMs) are important for the spatiotemporal organization of many protein complexes. In this study, we demonstrate that interactions between lamin A, a major component of the nuclear lamina, and SUMO isoforms are dependent on one of the four SIMs (SIM3) resided in lamin A polypeptide in vitro. Live cell imaging and immunofluorescence staining showed that SIM3 is required for accumulation of lamin A on the chromosomes during telophase, and subsequent evaluation of a panel of deletion mutants determined that a 156-amino acid region spanning the carboxyl-terminal Ig-fold domain of lamin A is sufficient for this accumulation. Notably, mutation of SIM3 abrogated the dephosphorylation of mitosis-specific phosphorylation at Ser-22 of lamin A, which normally occurs during telophase, and the subsequent nuclear lamina reorganization. Furthermore, expression of a conjugation-defective SUMO2 mutant, which was previously shown to inhibit endogenous SUMOylation in a dominant-negative manner, also impaired the accumulation of wild type lamin A on telophase chromosomes. These findings suggest that interactions between SIM3 of lamin A and a putative SUMO2-modified protein plays an important role in the reorganization of the nuclear lamina at the end of mitosis. - Highlights: • Lamin A interacts with SUMO2 via a SUMO-interacting motif (SIM) in the Ig domain. • SIM3 of lamin A is responsible for chromosomal accumulation during telophase. • A 156-aa region spanning the Ig domain is sufficient for chromosomal accumulation. • Accumulation of lamin A is required for timely dephosphorylation on chromosomes. • A putative SUMO2-modified protein may mediate chromosomal accumulation of lamin

Lamin A reassembly at the end of mitosis is regulated by its SUMO-interacting motif

International Nuclear Information System (INIS)

Moriuchi, Takanobu; Kuroda, Masaki; Kusumoto, Fumiya; Osumi, Takashi; Hirose, Fumiko

2016-01-01

Modification of proteins with small ubiquitin-related modifier (SUMO; SUMOylation) is involved in the regulation of various biological processes. Recent studies have demonstrated that noncovalent associations between SUMOylated proteins and co-operative proteins containing SUMO-interacting motifs (SIMs) are important for the spatiotemporal organization of many protein complexes. In this study, we demonstrate that interactions between lamin A, a major component of the nuclear lamina, and SUMO isoforms are dependent on one of the four SIMs (SIM3) resided in lamin A polypeptide in vitro. Live cell imaging and immunofluorescence staining showed that SIM3 is required for accumulation of lamin A on the chromosomes during telophase, and subsequent evaluation of a panel of deletion mutants determined that a 156-amino acid region spanning the carboxyl-terminal Ig-fold domain of lamin A is sufficient for this accumulation. Notably, mutation of SIM3 abrogated the dephosphorylation of mitosis-specific phosphorylation at Ser-22 of lamin A, which normally occurs during telophase, and the subsequent nuclear lamina reorganization. Furthermore, expression of a conjugation-defective SUMO2 mutant, which was previously shown to inhibit endogenous SUMOylation in a dominant-negative manner, also impaired the accumulation of wild type lamin A on telophase chromosomes. These findings suggest that interactions between SIM3 of lamin A and a putative SUMO2-modified protein plays an important role in the reorganization of the nuclear lamina at the end of mitosis. - Highlights: • Lamin A interacts with SUMO2 via a SUMO-interacting motif (SIM) in the Ig domain. • SIM3 of lamin A is responsible for chromosomal accumulation during telophase. • A 156-aa region spanning the Ig domain is sufficient for chromosomal accumulation. • Accumulation of lamin A is required for timely dephosphorylation on chromosomes. • A putative SUMO2-modified protein may mediate chromosomal accumulation of lamin

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

Science.gov (United States)

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.

Cutaneous Sensory Block Area, Muscle-Relaxing Effect, and Block Duration of the Transversus Abdominis Plane Block

DEFF Research Database (Denmark)

Støving, Kion; Rothe, Christian; Rosenstock, Charlotte V

2015-01-01

BACKGROUND AND OBJECTIVES: The transversus abdominis plane (TAP) block is a widely used nerve block. However, basic block characteristics are poorly described. The purpose of this study was to assess the cutaneous sensory block area, muscle-relaxing effect, and block duration. METHODS: Sixteen...... healthy volunteers were randomized to receive an ultrasound-guided unilateral TAP block with 20 mL 7.5 mg/mL ropivacaine and placebo on the contralateral side. Measurements were performed at baseline and 90 minutes after performing the block. Cutaneous sensory block area was mapped and separated...... into a medial and lateral part by a vertical line through the anterior superior iliac spine. We measured muscle thickness of the 3 lateral abdominal muscle layers with ultrasound in the relaxed state and during maximal voluntary muscle contraction. The volunteers reported the duration of the sensory block...

31 CFR 594.301 - Blocked account; blocked property.

Science.gov (United States)

2010-07-01

... (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY GLOBAL TERRORISM SANCTIONS REGULATIONS General Definitions § 594.301 Blocked account; blocked property. The terms blocked account and...

Rab5 GTPase controls chromosome alignment through Lamin disassembly and relocation of the NuMA-like protein Mud to the poles during mitosis

Science.gov (United States)

Capalbo, Luisa; D'Avino, Pier Paolo; Archambault, Vincent; Glover, David M.

2011-01-01

The small GTPase Rab5 is a conserved regulator of membrane trafficking; it regulates the formation of early endosomes, their transport along microtubules, and the fusion to the target organelles. Although several members of the endocytic pathway were recently implicated in spindle organization, it is unclear whether Rab5 has any role during mitosis. Here, we describe that Rab5 is required for proper chromosome alignment during Drosophila mitoses. We also found that Rab5 associated in vivo with nuclear Lamin and mushroom body defect (Mud), the Drosophila counterpart of nuclear mitotic apparatus protein (NuMA). Consistent with this finding, Rab5 was required for the disassembly of the nuclear envelope at mitotic entry and the accumulation of Mud at the spindle poles. Furthermore, Mud depletion caused chromosome misalignment defects that resembled the defects of Rab5 RNAi cells, and double-knockdown experiments indicated that the two proteins function in a linear pathway. Our results indicate a role for Rab5 in mitosis and reinforce the emerging view of the contributions made by cell membrane dynamics to spindle function. PMID:21987826

Seed priming with iron and zinc in bread wheat: effects in germination, mitosis and grain yield.

Science.gov (United States)

Reis, Sara; Pavia, Ivo; Carvalho, Ana; Moutinho-Pereira, José; Correia, Carlos; Lima-Brito, José

2018-07-01

Currently, the biofortification of crops like wheat with micronutrients such as iron (Fe) and zinc (Zn) is extremely important due to the deficiencies of these micronutrients in the human diet and in soils. Agronomic biofortification with Fe and Zn can be done through different exogenous strategies such as soil application, foliar spraying, and seed priming. However, the excess of these micronutrients can be detrimental to the plants. Therefore, in the last decade, a high number of studies focused on the evaluation of their phytotoxic effects to define the best strategies for biofortification of bread wheat. In this study, we investigated the effects of seed priming with different dosages (1 mg L -1 to 8 mg L -1 ) of Fe and/or Zn in germination, mitosis and yield of bread wheat cv. 'Jordão' when compared with control. Overall, our results showed that: micronutrient dosages higher than 4 mg L -1 negatively affect the germination; Fe and/or Zn concentrations higher than 2 mg L -1 significantly decrease the mitotic index and increase the percentage of dividing cells with anomalies; treatments performed with 8 mg L -1 of Fe and/or 8 mg L -1 Zn caused negative effects in germination, mitosis and grain yield. Moreover, seed priming with 2 mg L -1 Fe + 2 mg L -1 Zn has been shown to be non-cytotoxic, ensuring a high rate of germination (80%) and normal dividing cells (90%) as well as improving tillering and grain yield. This work revealed that seed priming with Fe and Zn micronutrients constitutes a useful and alternative approach for the agronomic biofortification of bread wheat.

Aurora B kinase inhibition in mitosis: strategies for optimising the use of aurora kinase inhibitors such as AT9283.

Science.gov (United States)

Curry, Jayne; Angove, Hayley; Fazal, Lynsey; Lyons, John; Reule, Matthias; Thompson, Neil; Wallis, Nicola

2009-06-15

Aurora kinases play a key role in regulating mitotic division and are attractive oncology targets. AT9283, a multi-targeted kinase inhibitor with potent activity against Aurora A and B kinases, inhibited growth and survival of multiple solid tumor cell lines and was efficacious in mouse xenograft models. AT9283-treatment resulted in endoreduplication and ablation of serine-10 histone H3 phosphorylation in both cells and tumor samples, confirming that in these models it acts as an Aurora B kinase inhibitor. In vitro studies demonstrated that exposure to AT9283 for one complete cell cycle committed an entire population of p53 checkpoint-compromised cells (HCT116) to multinucleation and death whereas treatment of p53 checkpoint-competent cells (HMEC, A549) for a similar length of time led to a reversible arrest of cells with 4N DNA. Further studies in synchronized cell populations suggested that exposure to AT9283 during mitosis was critical for optimal cytotoxicity. We therefore investigated ways in which these properties might be exploited to optimize the efficacy and therapeutic index of Aurora kinase inhibitors for p53 checkpoint compromised tumors in vivo. Combining Aurora B kinase inhibition with paclitaxel, which arrests cells in mitosis, in a xenograft model resulted in promising efficacy without additional toxicity. These findings have implications for optimizing the efficacy of Aurora kinase inhibitors in clinical practice.

Chinese hamster ovary cell mitosis and its response to ionizing radiation: A morphological analysis of the living cell

International Nuclear Information System (INIS)

Carlson, J.G.

1989-01-01

Repeated microscopic observations of exponentially growing Chinese hamster ovary cells were made and the times and mitotic stages were recorded in control and irradiated cultures at 37 degree C. As determined by autoradiography, the time from the end of S phase to early prophase (the G2 phase) was 46 min, to breakdown of the nuclear envelope was 91 min, and to restoration of the nuclear envelope was 116 min. The time spent in morphologically distinguishable phases of mitosis and the effects of 0.5, 1.0, 1.5, 2.0, and 4.0 Gy of gamma or X radiation on cells at each phase were determined. Affected cells were found to be delayed without or with reversion to an earlier mitotic stage before recovering and advancing through mitosis. Cells were timed in the five steps comprising delay with reversion: inertia, cessation I, regression, cessation II, and reprogression. No cells treated in late prophase, i.e., within 8-10 min of nuclear envelope breakdown, were delayed by the doses used; therefore the critical or transition point must be situated in middle prophase. Cells irradiated in this stage were not delayed by 0.5 or 1.0 Gy, but suffered a dose-dependent delay with or without reversion after 1.5, 2.0, and 4.0 Gy. Cells irradiated in early prophase and very late interphase responded similarly, but a greater percentage of the latter reverted

["Habitual" left branch block alternating with 2 "disguised" bracnch block].

Science.gov (United States)

Lévy, S; Jullien, G; Mathieu, P; Mostefa, S; Gérard, R

1976-10-01

Two cases of alternating left bundle branch block and "masquerading block" (with left bundle branch morphology in the stnadard leads and right bundle branch block morphology in the precordial leads) were studied by serial tracings and his bundle electrocardiography. In case 1 "the masquerading" block was associated with a first degree AV block related to a prolongation of HV interval. This case is to our knowledge the first cas of alternating bundle branch block in which his bundle activity was recorded in man. In case 2, the patient had atrial fibrilation and His bundle recordings were performed while differents degrees of left bundle branch block were present: The mechanism of the alternation and the concept of "masquerading" block are discussed. It is suggested that this type of block represents a right bundle branch block associated with severe lesions of the "left system".

Novel Microtubule-Stabilizing Reagents

National Research Council Canada - National Science Library

Bulinski, Chloe J

2005-01-01

... [1]. Taxanes are widely used to halt breast tumors, because they block mitosis and metastasis, and promote apoptosis, though some breast cancers are unpredictably refractory to taxanes, even at levels...

Fission yeast cells undergo nuclear division in the absence of spindle microtubules.

Directory of Open Access Journals (Sweden)

Stefania Castagnetti

2010-10-01

Full Text Available Mitosis in eukaryotic cells employs spindle microtubules to drive accurate chromosome segregation at cell division. Cells lacking spindle microtubules arrest in mitosis due to a spindle checkpoint that delays mitotic progression until all chromosomes have achieved stable bipolar attachment to spindle microtubules. In fission yeast, mitosis occurs within an intact nuclear membrane with the mitotic spindle elongating between the spindle pole bodies. We show here that in fission yeast interference with mitotic spindle formation delays mitosis only briefly and cells proceed to an unusual nuclear division process we term nuclear fission, during which cells perform some chromosome segregation and efficiently enter S-phase of the next cell cycle. Nuclear fission is blocked if spindle pole body maturation or sister chromatid separation cannot take place or if actin polymerization is inhibited. We suggest that this process exhibits vestiges of a primitive nuclear division process independent of spindle microtubules, possibly reflecting an evolutionary intermediate state between bacterial and Archeal chromosome segregation where the nucleoid divides without a spindle and a microtubule spindle-based eukaryotic mitosis.

MiR-509-3-5p causes aberrant mitosis and anti-proliferative effect by suppression of PLK1 in human lung cancer A549 cells

International Nuclear Information System (INIS)

Wang, Xian-Hui; Lu, Yao; Liang, Jing-Jing; Cao, Ji-Xiang; Jin, Ya-Qiong; An, Guo-Shun; Ni, Ju-Hua; Jia, Hong-Ti; Li, Shu-Yan

2016-01-01

MicroRNAs (miRNAs) are potent post-transcriptional regulators of gene expression and play roles in DNA damage response (DDR). PLK1 is identified as a modulator of DNA damage checkpoint. Although down-regulation of PLK1 by certain microRNAs has been reported, little is known about the interplay between PLK1 and miR-509-3-5p in DDR. Here we have demonstrated that miR-509-3-5p repressed PLK1 expression by targeting PLK1 3′-UTR, thereby causing mitotic aberration and growth arrest of human lung cancer A549 cells. Repression of PLK1 by miR-509-3-5p was further evidenced by over-expression of miR-509-3-5p in A549, HepG2 and HCT116p53 −/− cancer cells, in which PLK1 protein was suppressed. Consistently, miR-509-3-5p was stimulated, while PLK1 protein was down-regulated in A549 cells exposed to CIS and ADR, suggesting that suppression of PLK1 by miR-509-3-5p is a component of CIS/ADR-induced DDR pathway. Flow cytometry and immunofluorescence labeling showed that over-expression of miR-509-3-5p in A549 induced G2/M arrest and aberrant mitosis characterized by abnormal bipolar mitotic spindles, condensed chromosomes, lagging DNA and chromosome bridges. In addition, over-expression of miR-509-3-5p markedly blocked A549 cell proliferation and sensitized the cells to CIS and ADR treatment. Taken together, miR-509-3-5p is a feasible suppressor for cancer by targeting PLK1. Our data may provide aid in potential design of combined chemotherapy and in our better understanding of the roles of microRNAs in response to DNA damage. - Highlights: • MiR-509-3-5p represses PLK1 expression by targeting PLK1 3ГЉВ№-UTR. • Expression of miR-509-3-5p is induced and PLK1 repressed upon DNA damage. • Overexpression of miR-509-3-5p induces G2/M arrest and aberrant mitosis. • MiR-509-3-5p inhibits cell proliferation and sensitizes cells to DNA damage agents.

Histochemical applications of x-ray microanalysis: the simultaneous assessment of mitosis and cell death

International Nuclear Information System (INIS)

Bowen, I.D.; Lewis, G.H.

1980-01-01

The principles of x-ray microanalytical histochemistry are reviewed. The use of labelling and precipitation techniques are examined, and particular attention is paid to the localization of enzymatic activity. A new method is described for the simultaneous assessment of mitosis as represented by the incorporation of ( 3 H) thymidine, and cell death as represented by the localization of free acid phosphatase, in the same tissue section. The thymidine incorporation is demonstrated by the appearance of topographically and microanalytically detectable silver grains in an overlying emulsion and the cell lysis associated acid phosphatase activity is detected optically and microanalytically by means of a bromine-rich azo dye deposited as a result of coupling naphthol AS BI, enzymatically released from naphthyl AS BI phosphoric acid, with diazotized 2,5-dibromoaniline

E-Block: A Tangible Programming Tool with Graphical Blocks

Directory of Open Access Journals (Sweden)

Danli Wang

2013-01-01

Full Text Available This paper designs a tangible programming tool, E-Block, for children aged 5 to 9 to experience the preliminary understanding of programming by building blocks. With embedded artificial intelligence, the tool defines the programming blocks with the sensors as the input and enables children to write programs to complete the tasks in the computer. The symbol on the programming block's surface is used to help children understanding the function of each block. The sequence information is transferred to computer by microcomputers and then translated into semantic information. The system applies wireless and infrared technologies and provides user with feedbacks on both screen and programming blocks. Preliminary user studies using observation and user interview methods are shown for E-Block's prototype. The test results prove that E-Block is attractive to children and easy to learn and use. The project also highlights potential advantages of using single chip microcomputer (SCM technology to develop tangible programming tools for children.

Discovery of new natural products by application of X-hitting, a novel algorithm for automated comparison of full UV-spectra, combined with structural determination by NMR spectroscophy

DEFF Research Database (Denmark)

Larsen, Thomas Ostenfeld; Petersen, Bent O.; Duus, Jens Øllgaard

2005-01-01

X-hitting, a newly developed algorithm for automated comparison of UV data, has been used for the tracking of two novel spiro-quinazoline metabolites, lapatins A (1)andB(2), in a screening study targeting quinazolines. The structures of 1 and 2 were elucidated by analysis of spectroscopic data...

G2 block in Chinese hamster cells induced by x-irradiation, hyperthermia, cycloheximide, or actinomycin-D

International Nuclear Information System (INIS)

Dewey, W.C.; Highfield, D.P.

1976-01-01

The entry of cells into mitosis was monitored by shaking off mitotic cells from monolayer cultures. The location in G 2 of the x-ray transition point (TP), beyond which the cells were not delayed by x irradiation moved closer to mitosis as the dose was increased, i.e., at 10 min before prophase for 100 to 200 rad, and at 19 min for 30 to 60 rad. Treatment with cycloheximide (CH, 20 μg/ml) at the time of irradiation (50 to 100 rad) shifted the TP for x irradiation by 5 to 9 min toward mitosis. Calculations from these shifts in TP with radiation dose indicated that the logarithm of both the fraction of cells in G 2 not delayed by irradiation and the fraction beyond the TP for CH (located at 26 min before phophase for 5 to 50 μg/ml) not delayed by irradiation decreased linearly with dose (anti D 0 of 30 rad). Furthermore, inhibition of protein synthesis by CH, with or without a simultaneous treatment with actinomycin D (AMD), prevented repair of damage causing mitotic delay for a period of time equal to the duration of the CH treatment

E-Block: A Tangible Programming Tool with Graphical Blocks

OpenAIRE

Danli Wang; Yang Zhang; Shengyong Chen

2013-01-01

This paper designs a tangible programming tool, E-Block, for children aged 5 to 9 to experience the preliminary understanding of programming by building blocks. With embedded artificial intelligence, the tool defines the programming blocks with the sensors as the input and enables children to write programs to complete the tasks in the computer. The symbol on the programming block's surface is used to help children understanding the function of each block. The sequence information is transfer...

Cellular responses to a prolonged delay in mitosis are determined by a DNA damage response controlled by Bcl-2 family proteins.

Science.gov (United States)

Colin, Didier J; Hain, Karolina O; Allan, Lindsey A; Clarke, Paul R

2015-03-01

Anti-cancer drugs that disrupt mitosis inhibit cell proliferation and induce apoptosis, although the mechanisms of these responses are poorly understood. Here, we characterize a mitotic stress response that determines cell fate in response to microtubule poisons. We show that mitotic arrest induced by these drugs produces a temporally controlled DNA damage response (DDR) characterized by the caspase-dependent formation of γH2AX foci in non-apoptotic cells. Following exit from a delayed mitosis, this initial response results in activation of DDR protein kinases, phosphorylation of the tumour suppressor p53 and a delay in subsequent cell cycle progression. We show that this response is controlled by Mcl-1, a regulator of caspase activation that becomes degraded during mitotic arrest. Chemical inhibition of Mcl-1 and the related proteins Bcl-2 and Bcl-xL by a BH3 mimetic enhances the mitotic DDR, promotes p53 activation and inhibits subsequent cell cycle progression. We also show that inhibitors of DDR protein kinases as well as BH3 mimetics promote apoptosis synergistically with taxol (paclitaxel) in a variety of cancer cell lines. Our work demonstrates the role of mitotic DNA damage responses in determining cell fate in response to microtubule poisons and BH3 mimetics, providing a rationale for anti-cancer combination chemotherapies.

Origin of the cell nucleus, mitosis and sex: roles of intracellular coevolution

Directory of Open Access Journals (Sweden)

Cavalier-Smith Thomas

2010-02-01

Full Text Available Abstract Background The transition from prokaryotes to eukaryotes was the most radical change in cell organisation since life began, with the largest ever burst of gene duplication and novelty. According to the coevolutionary theory of eukaryote origins, the fundamental innovations were the concerted origins of the endomembrane system and cytoskeleton, subsequently recruited to form the cell nucleus and coevolving mitotic apparatus, with numerous genetic eukaryotic novelties inevitable consequences of this compartmentation and novel DNA segregation mechanism. Physical and mutational mechanisms of origin of the nucleus are seldom considered beyond the long-standing assumption that it involved wrapping pre-existing endomembranes around chromatin. Discussions on the origin of sex typically overlook its association with protozoan entry into dormant walled cysts and the likely simultaneous coevolutionary, not sequential, origin of mitosis and meiosis. Results I elucidate nuclear and mitotic coevolution, explaining the origins of dicer and small centromeric RNAs for positionally controlling centromeric heterochromatin, and how 27 major features of the cell nucleus evolved in four logical stages, making both mechanisms and selective advantages explicit: two initial stages (origin of 30 nm chromatin fibres, enabling DNA compaction; and firmer attachment of endomembranes to heterochromatin protected DNA and nascent RNA from shearing by novel molecular motors mediating vesicle transport, division, and cytoplasmic motility. Then octagonal nuclear pore complexes (NPCs arguably evolved from COPII coated vesicle proteins trapped in clumps by Ran GTPase-mediated cisternal fusion that generated the fenestrated nuclear envelope, preventing lethal complete cisternal fusion, and allowing passive protein and RNA exchange. Finally, plugging NPC lumens by an FG-nucleoporin meshwork and adopting karyopherins for nucleocytoplasmic exchange conferred compartmentation

PSK, a biological response modifier, modifies p53 expression, mitosis and apoptosis in X-ray irradiated mouse embryos. Possible cellular mechanism of the anti-teratogenic effect

International Nuclear Information System (INIS)

Kagohashi, Yukiko; Naora, Hiroyuki; Otani, Hiroki

2002-01-01

We previously showed that PSK, a biological response modifier, suppressed X-ray irradiation induced ocular anomalies in mouse embryos. In the present study, in mouse embryos irradiated at E7.5, PSK, when administered immediately after irradiation, suppressed mitosis and increased apoptosis as compared with embryos not treated with PSK at 12 hrs after irradiation. In the irradiated embryos, p53, which is normally expressed at a high level in early embryos, increased at 6 hrs and decreased at 12 hrs after irradiation. In the irradiated and PSK-treated embryos, the p53 level did not change at 6 hrs, increased at 12 hrs and decreased at 24 hrs after irradiation. This timing of PSK-induced delayed increase of p53 coincided with that of the PSK-induced decrease in mitosis and increase in apoptosis. These results suggested that PSK modified the p53 level and affected cell proliferation and apoptosis, which might contribute to the suppression of teratogenesis. (author)

JNK Controls the Onset of Mitosis in Planarian Stem Cells and Triggers Apoptotic Cell Death Required for Regeneration and Remodeling

Science.gov (United States)

Almuedo-Castillo, María; Crespo, Xenia; Seebeck, Florian; Bartscherer, Kerstin; Salò, Emili; Adell, Teresa

2014-01-01

Regeneration of lost tissues depends on the precise interpretation of molecular signals that control and coordinate the onset of proliferation, cellular differentiation and cell death. However, the nature of those molecular signals and the mechanisms that integrate the cellular responses remain largely unknown. The planarian flatworm is a unique model in which regeneration and tissue renewal can be comprehensively studied in vivo. The presence of a population of adult pluripotent stem cells combined with the ability to decode signaling after wounding enable planarians to regenerate a complete, correctly proportioned animal within a few days after any kind of amputation, and to adapt their size to nutritional changes without compromising functionality. Here, we demonstrate that the stress-activated c-jun–NH2–kinase (JNK) links wound-induced apoptosis to the stem cell response during planarian regeneration. We show that JNK modulates the expression of wound-related genes, triggers apoptosis and attenuates the onset of mitosis in stem cells specifically after tissue loss. Furthermore, in pre-existing body regions, JNK activity is required to establish a positive balance between cell death and stem cell proliferation to enable tissue renewal, remodeling and the maintenance of proportionality. During homeostatic degrowth, JNK RNAi blocks apoptosis, resulting in impaired organ remodeling and rescaling. Our findings indicate that JNK-dependent apoptotic cell death is crucial to coordinate tissue renewal and remodeling required to regenerate and to maintain a correctly proportioned animal. Hence, JNK might act as a hub, translating wound signals into apoptotic cell death, controlled stem cell proliferation and differentiation, all of which are required to coordinate regeneration and tissue renewal. PMID:24922054

RPL41, a Small Ribosomal Peptide Deregulated in Tumors, Is Essential for Mitosis and Centrosome Integrity

Directory of Open Access Journals (Sweden)

Shan Wang

2010-03-01

Full Text Available Ribosomal large subunit protein RPL41 is a basic (positively charged peptide consisting of only 25 amino acids. An antisense-based functional screening revealed that the down-regulation of RPL41 led to an anchorage-independent growth of NIH3T3 cells in soft agar plates. RPL41 depletion with gene-specific small interfering RNA also resulted in malignant transformation of NIH3T3 cells including increased tumor growth in mice. RPL41 deletion was detected in 59% of tumor cell lines by fluorescence in situ hybridization analyses and RPL41 down-regulation in 75% of primary breast cancers by real-time quantitative reverse transcription-polymerase chain reaction. These studies suggest a tumor suppression role for RPL41. By mass spectrometry, RPL41 was associated with several cytoskeleton components including tubulin β, γ, and myosin IIA, which was confirmed by Western blot analysis on both cellular lysis and individually in vitro-expressed proteins. RPL41 also bound directly to polymerized tubulins. Cells overexpressing a GFP-RPL41 were resistant to nocodazole-induced microtubule depolymerization. A synthetic RPL41 induced cellular α-tubulin acetylation and G2/M cell cycle arrest. These results indicate a stabilizing role of RPL41 on microtubule. Microtubule spindles are essential for chromosome segregation during mitosis. Cells with RPL41 knock-down showed abnormal spindles, frequent failure of cytokinesis, and formation of polynuclear cells. In interphase cells, RPL41-depleted cells had premature splitting of centrosome. Our results provide evidence that RPL41 is a microtubule-associated protein essential for functional spindles and for the integrity of centrosome and that the abnormal mitosis and disrupted centrosome associated with the RPL41 down-regulation may be related to malignant transformation.

Cytogenetic analysis of the first two mitosis in seedling root meristems of stored for a long period seeds of Crepis tectorum populations subjected to chronic irradiation in 30-km zone of Chernobyl

International Nuclear Information System (INIS)

Grinikh, L.I.; Shevchenko, V.V.

1994-01-01

Seeds of Crepis tectorum natural populations 1 and 3 subjected to chronic irradiation in 1986 during 4 months in 30-kilometers zone of Chernobyl were stored for 6 years in a laboratory. In analysis of chromosome aberrations in the first tetraploid cells was made as it was done in 1987 just after finishing of a dromant period of seeds. By extrapolation from the data obtained by studing cells of the second colchicine mitosis to the cells of the previous mitosis from which they derived it was shown that the frequency of chromaid type aberrations in the early dividing cells after 6 year storage remained at the level which was observed just after finishing of a dormant period

The PP2AB56 phosphatase promotes the association of Cdc20 with APC/C in mitosis.

Science.gov (United States)

Lee, Sun Joo; Rodriguez-Bravo, Veronica; Kim, Hyunjung; Datta, Sutirtha; Foley, Emily A

2017-05-15

PP2A comprising B56 regulatory subunit isoforms (PP2A B56 ) is a serine/threonine phosphatase essential for mitosis. At the kinetochore, PP2A B56 both stabilizes microtubule binding and promotes silencing of the spindle assembly checkpoint (SAC) through its association with the SAC protein BubR1. Cells depleted of the B56 regulatory subunits of PP2A are delayed in activation of Cdc20-containing APC/C (APC/C Cdc20 ), which is an essential step for mitotic exit. It has been hypothesized that this delay arises from increased production of the mitotic checkpoint complex (MCC), an APC/C Cdc20 inhibitor formed at unattached kinetochores through SAC signaling. In contrast to this prediction, we show that depletion of B56 subunits does not increase the amount or stability of the MCC. Rather, delays in APC/C Cdc20 activation in B56-depleted cells correlate with impaired Cdc20 binding to APC/C. Stimulation of APC/C Cdc20 assembly does not require binding between PP2A B56 and BubR1, and thus this contribution of PP2A B56 towards mitotic exit is distinct from its functions at kinetochores. PP2A B56 associates with APC/C constitutively in a BubR1-independent manner. A mitotic phosphorylation site on Cdc20, known to be a substrate of PP2A B56 , modulates APC/C Cdc20 assembly. These results elucidate the contributions of PP2A B56 towards completion of mitosis. © 2017. Published by The Company of Biologists Ltd.

Centrioles are freed from cilia by severing prior to mitosis.

Science.gov (United States)

Parker, Jeremy D K; Hilton, Laura K; Diener, Dennis R; Rasi, M Qasim; Mahjoub, Moe R; Rosenbaum, Joel L; Quarmby, Lynne M

2010-07-01

Cilia are necessary for normal tissue development and homeostasis and are generally present during interphase, but not in mitosis. The precise mechanism of premitotic ciliary loss has been controversial, with data supporting either sequential disassembly through the transition zone or, alternatively, a severing event at the base of the cilia. Here we show by live cell imaging and immunofluorescence microscopy that resorbing flagella of Chlamydomonas leave remnants associated with the mother cell wall. We postulated that the remnants are the product of severing of doublet microtubules between the basal bodies and the flagellar transition zone, thereby freeing the centrioles to participate in spindle organization. We show via TEM that flagellar remnants are indeed flagellar transition zones encased in vesicles derived from the flagellar membrane. This transition zone vesicle can be lodged within the cell wall or it can be expelled into the environment. This process is observable in Chlamydomonas, first because the released flagellar remnants can remain associated with the cell by virtue of attachments to the cell wall, and second because the Chlamydomonas transition zone is particularly rich with electron-dense structure. However, release of basal bodies for spindle-associated function is likely to be conserved among the eukaryotes. 2010 Wiley-Liss, Inc.

Unique properties of multiple tandem copies of the M26 recombination hotspot in mitosis and meiosis in Schizosaccharomyces pombe.

Science.gov (United States)

Steiner, Walter W; Recor, Chelsea L; Zakrzewski, Bethany M

2016-11-15

The M26 hotspot of the fission yeast Schizosaccharomyces pombe is one of the best-characterized eukaryotic hotspots of recombination. The hotspot requires a seven bp sequence, ATGACGT, that serves as a binding site for the Atf1-Pcr1 transcription factor, which is also required for activity. The M26 hotspot is active in meiosis but not mitosis and is active in some but not all chromosomal contexts and not on a plasmid. A longer palindromic version of M26, ATGACGTCAT, shows significantly greater activity than the seven bp sequence. Here, we tested whether the properties of the seven bp sequence were also true of the longer sequence by placing one, two, or three copies of the sequence into the ade6 gene, where M26 was originally discovered. These constructs were tested for activity when located on a plasmid or on a chromosome in mitosis and meiosis. We found that two copies of the 10bp M26 motif on a chromosome were significantly more active for meiotic recombination than one, but no further increase was observed with three copies. However, three copies of M26 on a chromosome created an Atf1-dependent mitotic recombination hotspot. When located on a plasmid, M26 also appears to behave as a mitotic recombination hotspot; however, this behavior most likely results from Atf1-dependent inter-allelic complementation between the plasmid and chromosomal ade6 alleles. Copyright © 2016 Elsevier B.V. All rights reserved.

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.

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.

Poly(ferrocenylsilane)-block-Polylactide Block Copolymers

NARCIS (Netherlands)

Roerdink, M.; van Zanten, Thomas S.; Hempenius, Mark A.; Zhong, Zhiyuan; Feijen, Jan; Vancso, Gyula J.

2007-01-01

A PFS/PLA block copolymer was studied to probe the effect of strong surface interactions on pattern formation in PFS block copolymer thin films. Successful synthesis of PFS-b-PLA was demonstrated. Thin films of these polymers show phase separation to form PFS microdomains in a PLA matrix, and

Molecular networks linked by Moesin drive remodeling of the cell cortex during mitosis

Science.gov (United States)

Roubinet, Chantal; Decelle, Barbara; Chicanne, Gaëtan; Dorn, Jonas F.; Payrastre, Bernard; Payre, François; Carreno, Sébastien

2011-01-01

The cortical mechanisms that drive the series of mitotic cell shape transformations remain elusive. In this paper, we identify two novel networks that collectively control the dynamic reorganization of the mitotic cortex. We demonstrate that Moesin, an actin/membrane linker, integrates these two networks to synergize the cortical forces that drive mitotic cell shape transformations. We find that the Pp1-87B phosphatase restricts high Moesin activity to early mitosis and down-regulates Moesin at the polar cortex, after anaphase onset. Overactivation of Moesin at the polar cortex impairs cell elongation and thus cytokinesis, whereas a transient recruitment of Moesin is required to retract polar blebs that allow cortical relaxation and dissipation of intracellular pressure. This fine balance of Moesin activity is further adjusted by Skittles and Pten, two enzymes that locally produce phosphoinositol 4,5-bisphosphate and thereby, regulate Moesin cortical association. These complementary pathways provide a spatiotemporal framework to explain how the cell cortex is remodeled throughout cell division. PMID:21969469

Unconventional actin conformations localize on intermediate filaments in mitosis

International Nuclear Information System (INIS)

Hubert, Thomas; Vandekerckhove, Joel; Gettemans, Jan

2011-01-01

Research highlights: → Unconventional actin conformations colocalize with vimentin on a cage-like structure in metaphase HEK 293T cells. → These conformations are detected with the anti-actin antibodies 1C7 ('lower dimer') and 2G2 ('nuclear actin'), but not C4 (monomeric actin). → Mitotic unconventional actin cables are independent of filamentous actin or microtubules. → Unconventional actin colocalizes with vimentin on a nocodazole-induced perinuclear dense mass of cables. -- Abstract: Different structural conformations of actin have been identified in cells and shown to reside in distinct subcellular locations of cells. In this report, we describe the localization of actin on a cage-like structure in metaphase HEK 293T cells. Actin was detected with the anti-actin antibodies 1C7 and 2G2, but not with the anti-actin antibody C4. Actin contained in this structure is independent of microtubules and actin filaments, and colocalizes with vimentin. Taking advantage of intermediate filament collapse into a perinuclear dense mass of cables when microtubules are depolymerized, we were able to relocalize actin to such structures. We hypothesize that phosphorylation of intermediate filaments at mitosis entry triggers the recruitment of different actin conformations to mitotic intermediate filaments. Storage and partition of the nuclear actin and antiparallel 'lower dimer' actin conformations between daughter cells possibly contribute to gene transcription and transient actin filament dynamics at G1 entry.

Effect of paclitaxel (TAXOL) alone and in combination with radiation on the gastrointestinal mucosa

International Nuclear Information System (INIS)

Mason, K.A.; Milas, L.; Peters, L.J.

1995-01-01

Paclitaxel is a potentially useful drug for augmenting the cytotoxic action of radiotherapy because it has independent cytotoxic activity against certain cancers and blocks cells in the radiosensitive mitotic phase of the cell cycle. However, all rapidly proliferating tissues, both normal and neoplastic, may be affected by this therapeutic strategy. The aim of this study was to define the in vivo response of rapidly dividing cells of the small bowel mucosa in mice to paclitaxel given alone and in combination with radiation. Paclitaxel blocked jejunal crypt cells in mitosis and induced apoptosis in a dose-dependent manner. Fractionating the paclitaxel dose over 1-4 days did not result in any greater accumulation of mitotically blocked cells than did a single dose. Mitosis peaked 2-4 h after paclitaxel and returned to near normal by 24 h. Apoptosis lagged several hours behind mitosis and peaked about 6 h later than mitosis. Despite these kinetic perturbations, there was little or no enhancement of radiation effect when single doses were delivered 2-4 h after paclitaxel administration. The maximum sensitizer enhancement ratio of 1.07 observed after a single paclitaxel dose of 40 mg/kg is consistent with independent crypt cell killing. Conversely, when radiation was given 24 h after paclitaxel, a significant protective effect of the drug (SER 0.89-0.92), most probably due to a regenerative overshoot induced by paclitaxel, was observed. Stem cells of the jejunal mucosa determining radiation response were not radiosensitized by paclitaxel with the drug concentrations and dose deliver schedules used, although additive cytotoxicity was observed with the highest drug dose. A radioprotective effect was observed when radiation was given 24 h after paclitaxel administration. 33 refs., 4 figs., 3 tabs

Block and sub-block boundary strengthening in lath martensite

NARCIS (Netherlands)

Du, C.; Hoefnagels, J.P.M.; Vaes, R.; Geers, M.G.D.

2016-01-01

Well-defined uniaxial micro-tensile tests were performed on lath martensite single block specimens and multi-block specimens with different number of block boundaries parallel to the loading direction. Detailed slip trace analyses consistently revealed that in the {110}<111> slip system with the

On the Eigenvalues and Eigenvectors of Block Triangular Preconditioned Block Matrices

KAUST Repository

Pestana, Jennifer

2014-01-01

Block lower triangular matrices and block upper triangular matrices are popular preconditioners for 2×2 block matrices. In this note we show that a block lower triangular preconditioner gives the same spectrum as a block upper triangular preconditioner and that the eigenvectors of the two preconditioned matrices are related. © 2014 Society for Industrial and Applied Mathematics.

Powder wastes confinement block and manufacturing process of this block

International Nuclear Information System (INIS)

Dagot, L.; Brunel, G.

1996-01-01

This invention concerns a powder wastes containment block and a manufacturing process of this block. In this block, the waste powder is encapsulated in a thermo hardening polymer as for example an epoxy resin, the encapsulated resin being spread into cement. This block can contain between 45 and 55% in mass of wastes, between 18 and 36% in mass of polymer and between 14 and 32% in mass of cement. Such a containment block can be used for the radioactive wastes storage. (O.M.). 4 refs

Blocked Randomization with Randomly Selected Block Sizes

Directory of Open Access Journals (Sweden)

Jimmy Efird

2010-12-01

Full Text Available When planning a randomized clinical trial, careful consideration must be given to how participants are selected for various arms of a study. Selection and accidental bias may occur when participants are not assigned to study groups with equal probability. A simple random allocation scheme is a process by which each participant has equal likelihood of being assigned to treatment versus referent groups. However, by chance an unequal number of individuals may be assigned to each arm of the study and thus decrease the power to detect statistically significant differences between groups. Block randomization is a commonly used technique in clinical trial design to reduce bias and achieve balance in the allocation of participants to treatment arms, especially when the sample size is small. This method increases the probability that each arm will contain an equal number of individuals by sequencing participant assignments by block. Yet still, the allocation process may be predictable, for example, when the investigator is not blind and the block size is fixed. This paper provides an overview of blocked randomization and illustrates how to avoid selection bias by using random block sizes.

Population Blocks.

Science.gov (United States)

Smith, Martin H.

1992-01-01

Describes an educational game called "Population Blocks" that is designed to illustrate the concept of exponential growth of the human population and some potential effects of overpopulation. The game material consists of wooden blocks; 18 blocks are painted green (representing land), 7 are painted blue (representing water); and the remaining…

Stress induced by premature chromatin condensation triggers chromosome shattering and chromothripsis at DNA sites still replicating in micronuclei or multinucleate cells when primary nuclei enter mitosis.

Science.gov (United States)

Terzoudi, Georgia I; Karakosta, Maria; Pantelias, Antonio; Hatzi, Vasiliki I; Karachristou, Ioanna; Pantelias, Gabriel

2015-11-01

Combination of next-generation DNA sequencing, single nucleotide polymorphism array analyses and bioinformatics has revealed the striking phenomenon of chromothripsis, described as complex genomic rearrangements acquired in a single catastrophic event affecting one or a few chromosomes. Via an unproven mechanism, it is postulated that mechanical stress causes chromosome shattering into small lengths of DNA, which are then randomly reassembled by DNA repair machinery. Chromothripsis is currently examined as an alternative mechanism of oncogenesis, in contrast to the present paradigm that considers a stepwise development of cancer. While evidence for the mechanism(s) underlying chromosome shattering during cancer development remains elusive, a number of hypotheses have been proposed to explain chromothripsis, including ionizing radiation, DNA replication stress, breakage-fusion-bridge cycles, micronuclei formation and premature chromosome compaction. In the present work, we provide experimental evidence on the mechanistic basis of chromothripsis and on how chromosomes can get locally shattered in a single catastrophic event. Considering the dynamic nature of chromatin nucleoprotein complex, capable of rapid unfolding, disassembling, assembling and refolding, we first show that chromatin condensation at repairing or replicating DNA sites induces the mechanical stress needed for chromosome shattering to ensue. Premature chromosome condensation is then used to visualize the dynamic nature of interphase chromatin and demonstrate that such mechanical stress and chromosome shattering can also occur in chromosomes within micronuclei or asynchronous multinucleate cells when primary nuclei enter mitosis. Following an aberrant mitosis, chromosomes could find themselves in the wrong place at the wrong time so that they may undergo massive DNA breakage and rearrangement in a single catastrophic event. Specifically, our results support the hypothesis that premature chromosome

Wound-induced endogenous jasmonates stunt plant growth by inhibiting mitosis.

Directory of Open Access Journals (Sweden)

Yi Zhang

Full Text Available When plants are repeatedly injured their growth is stunted and the size of organs such as leaves is greatly reduced. The basis of this effect is not well-understood however, even though it reduces yield of crops injured by herbivory, and produces dramatic effects exemplified in ornamental bonsai plants. We have investigated the genetic and physiological basis of this "bonsai effect" by repeatedly wounding leaves of the model plant Arabidopsis. This treatment stunted growth by 50% and increased the endogenous content of jasmonate (JA, a growth inhibitor, by seven-fold. Significantly, repeated wounding did not stunt the growth of the leaves of mutants unable to synthesise JA, or unable to respond to JA including coi1, jai3, myc2, but not jar1. The stunted growth did not result from reduced cell size, but resulted instead from reduced cell number, and was associated with reduced expression of CycB1;2. Wounding caused systemic disappearance of constitutively expressed JAZ1::GUS. Wounding also activates plant immunity. We show that a gene, 12-oxo-phytodienoate reductase, which catalyses a step in JA biosynthesis, and which we confirm is not required for defence, is however required for wound-induced stunting. Our data suggest that intermediates in the JA biosynthetic pathway activate defence, but a primary function of wound-induced JA is to stunt growth through the suppression of mitosis.

Wound-induced endogenous jasmonates stunt plant growth by inhibiting mitosis.

Science.gov (United States)

Zhang, Yi; Turner, John G

2008-01-01

When plants are repeatedly injured their growth is stunted and the size of organs such as leaves is greatly reduced. The basis of this effect is not well-understood however, even though it reduces yield of crops injured by herbivory, and produces dramatic effects exemplified in ornamental bonsai plants. We have investigated the genetic and physiological basis of this "bonsai effect" by repeatedly wounding leaves of the model plant Arabidopsis. This treatment stunted growth by 50% and increased the endogenous content of jasmonate (JA), a growth inhibitor, by seven-fold. Significantly, repeated wounding did not stunt the growth of the leaves of mutants unable to synthesise JA, or unable to respond to JA including coi1, jai3, myc2, but not jar1. The stunted growth did not result from reduced cell size, but resulted instead from reduced cell number, and was associated with reduced expression of CycB1;2. Wounding caused systemic disappearance of constitutively expressed JAZ1::GUS. Wounding also activates plant immunity. We show that a gene, 12-oxo-phytodienoate reductase, which catalyses a step in JA biosynthesis, and which we confirm is not required for defence, is however required for wound-induced stunting. Our data suggest that intermediates in the JA biosynthetic pathway activate defence, but a primary function of wound-induced JA is to stunt growth through the suppression of mitosis.

Minimum description length block finder, a method to identify haplotype blocks and to compare the strength of block boundaries.

Science.gov (United States)

Mannila, H; Koivisto, M; Perola, M; Varilo, T; Hennah, W; Ekelund, J; Lukk, M; Peltonen, L; Ukkonen, E

2003-07-01

We describe a new probabilistic method for finding haplotype blocks that is based on the use of the minimum description length (MDL) principle. We give a rigorous definition of the quality of a segmentation of a genomic region into blocks and describe a dynamic programming algorithm for finding the optimal segmentation with respect to this measure. We also describe a method for finding the probability of a block boundary for each pair of adjacent markers: this gives a tool for evaluating the significance of each block boundary. We have applied the method to the published data of Daly and colleagues. The results expose some problems that exist in the current methods for the evaluation of the significance of predicted block boundaries. Our method, MDL block finder, can be used to compare block borders in different sample sets, and we demonstrate this by applying the MDL-based method to define the block structure in chromosomes from population isolates.

Effect of Paclitaxel (Taxol) alone and in combination with radiation on the gastrointestinal mucosa

International Nuclear Information System (INIS)

Mason, Kathryn Ann; Milas, Luka; Peters, Lester J.

1995-01-01

Purpose: Paclitaxel is a potentially useful drug for augmenting the cytotoxic action of radiotherapy because it has independent cytotoxic activity against certain cancers and blocks cells in the radiosensitive mitotic phase of the cell cycle. However, all rapidly proliferating tissues, both normal and neoplastic, may be affected by this therapeutic strategy. The aim of this study was to define the in vivo response of rapidly dividing cells of the small bowel mucosa to paclitaxel given alone and in combination with radiation. Methods and Materials: Mice were given single IV doses of 10 or 40 mg/kg paclitaxel or four doses of 10 mg/kg paclitaxel at 6, 12, or 24 h intervals. The kinetics of mitotic arrest and apoptosis in jejunal crypts of mice at 1-24 h after treatment were defined histologically. An in vivo stem cell microcolony assay was used to assess the radiosensitizing potential of paclitaxel when radiation was delivered at the peak of mitosis and at 24 h after drug treatment. Results: Paclitaxel blocked jejunal crypt cells in mitosis and induced apoptosis in a dose-dependent manner. Fractionating the paclitaxel dose over 1-4 days did not result in any greater accumulation of mitotically blocked cells than did a single dose. Mitosis peaked 2-4 h after paclitaxel and returned to near normal by 24 h. Apoptosis lagged several hours behind mitosis and peaked about 6 h later than mitosis. Despite these kinetic perturbations, there was little or no enhancement of radiation effect when single doses were delivered 2-4 h after paclitaxel administration. The maximum sensitizer enhancement ratio of 1.07 observed after a single paclitaxel dose of 40 mg/kg is consistent with independent crypt cell killing. Conversely, when radiation was given 24 h after paclitaxel, a significant protective effect of the drug (SER 0.89-0.92), most probably due to a regenerative overshoot induced by paclitaxel, was observed. Conclusion: Stem cells of the jejunal mucosa determining radiation

A plant cyclin B2 is degraded early in mitosis and its ectopic expression shortens G2-phase and alleviates the DNA-damage checkpoint

Czech Academy of Sciences Publication Activity Database

Weingartner, M.; Pelayo, H. R.; Binarová, Pavla; Zwerger, K.; Melikant, B.; Torre, C.; Heberle-Bors, E.; Bogre, L.

2003-01-01

Roč. 116, č. 3 (2003), s. 487-498 ISSN 0021-9533 R&D Projects: GA MŠk LN00A081 Grant - others:GA Ministerio de Ciencia y Tecnologia(ES) BMC2001-2195; Biotechnology and Biological Science Research Council(AU) 111/P133340 Institutional research plan: CEZ:AV0Z5020903 Keywords : cyclin B * mitosis * checkpoint Subject RIV: EE - Microbiology, Virology Impact factor: 7.250, year: 2003

Mutations in genes encoding condensin complex proteins cause microcephaly through decatenation failure at mitosis.

Science.gov (United States)

Martin, Carol-Anne; Murray, Jennie E; Carroll, Paula; Leitch, Andrea; Mackenzie, Karen J; Halachev, Mihail; Fetit, Ahmed E; Keith, Charlotte; Bicknell, Louise S; Fluteau, Adeline; Gautier, Philippe; Hall, Emma A; Joss, Shelagh; Soares, Gabriela; Silva, João; Bober, Michael B; Duker, Angela; Wise, Carol A; Quigley, Alan J; Phadke, Shubha R; Wood, Andrew J; Vagnarelli, Paola; Jackson, Andrew P

2016-10-01

Compaction of chromosomes is essential for accurate segregation of the genome during mitosis. In vertebrates, two condensin complexes ensure timely chromosome condensation, sister chromatid disentanglement, and maintenance of mitotic chromosome structure. Here, we report that biallelic mutations in NCAPD2, NCAPH, or NCAPD3, encoding subunits of these complexes, cause microcephaly. In addition, hypomorphic Ncaph2 mice have significantly reduced brain size, with frequent anaphase chromatin bridge formation observed in apical neural progenitors during neurogenesis. Such DNA bridges also arise in condensin-deficient patient cells, where they are the consequence of failed sister chromatid disentanglement during chromosome compaction. This results in chromosome segregation errors, leading to micronucleus formation and increased aneuploidy in daughter cells. These findings establish "condensinopathies" as microcephalic disorders, with decatenation failure as an additional disease mechanism for microcephaly, implicating mitotic chromosome condensation as a key process ensuring mammalian cerebral cortex size. © 2016 Martin et al.; Published by Cold Spring Harbor Laboratory Press.

CS2164, a novel multi-target inhibitor against tumor angiogenesis, mitosis and chronic inflammation with anti-tumor potency.

Science.gov (United States)

Zhou, You; Shan, Song; Li, Zhi-Bin; Xin, Li-Jun; Pan, De-Si; Yang, Qian-Jiao; Liu, Ying-Ping; Yue, Xu-Peng; Liu, Xiao-Rong; Gao, Ji-Zhou; Zhang, Jin-Wen; Ning, Zhi-Qiang; Lu, Xian-Ping

2017-03-01

Although inhibitors targeting tumor angiogenic pathway have provided improvement for clinical treatment in patients with various solid tumors, the still very limited anti-cancer efficacy and acquired drug resistance demand new agents that may offer better clinical benefits. In the effort to find a small molecule potentially targeting several key pathways for tumor development, we designed, discovered and evaluated a novel multi-kinase inhibitor, CS2164. CS2164 inhibited the angiogenesis-related kinases (VEGFR2, VEGFR1, VEGFR3, PDGFRα and c-Kit), mitosis-related kinase Aurora B and chronic inflammation-related kinase CSF-1R in a high potency manner with the IC 50 at a single-digit nanomolar range. Consequently, CS2164 displayed anti-angiogenic activities through suppression of VEGFR/PDGFR phosphorylation, inhibition of ligand-dependent cell proliferation and capillary tube formation, and prevention of vasculature formation in tumor tissues. CS2164 also showed induction of G2/M cell cycle arrest and suppression of cell proliferation in tumor tissues through the inhibition of Aurora B-mediated H3 phosphorylation. Furthermore, CS2164 demonstrated the inhibitory effect on CSF-1R phosphorylation that led to the suppression of ligand-stimulated monocyte-to-macrophage differentiation and reduced CSF-1R + cells in tumor tissues. The in vivo animal efficacy studies revealed that CS2164 induced remarkable regression or complete inhibition of tumor growth at well-tolerated oral doses in several human tumor xenograft models. Collectively, these results indicate that CS2164 is a highly selective multi-kinase inhibitor with potent anti-tumor activities against tumor angiogenesis, mitosis and chronic inflammation, which may provide the rationale for further clinical assessment of CS2164 as a therapeutic agent in the treatment of cancer. © 2016 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.

Generalized Block Failure

DEFF Research Database (Denmark)

Jönsson, Jeppe

2015-01-01

Block tearing is considered in several codes as a pure block tension or a pure block shear failure mechanism. However in many situations the load acts eccentrically and involves the transfer of a substantial moment in combination with the shear force and perhaps a normal force. A literature study...... shows that no readily available tests with a well-defined substantial eccentricity have been performed. This paper presents theoretical and experimental work leading towards generalized block failure capacity methods. Simple combination of normal force, shear force and moment stress distributions along...... yield lines around the block leads to simple interaction formulas similar to other interaction formulas in the codes....

The DNA-dependent protein kinase: a multifunctional protein kinase with roles in DNA double strand break repair and mitosis

Science.gov (United States)

Jette, Nicholas; Lees-Miller, Susan P.

2015-01-01

The DNA-dependent protein kinase (DNA-PK) is a serine/threonine protein kinase composed of a large catalytic subunit (DNA-PKcs) and the Ku70/80 heterodimer. Over the past two decades, significant progress has been made in elucidating the role of DNA-PK in non-homologous end joining (NHEJ), the major pathway for repair of ionizing radiation-induced DNA double strand breaks in human cells and recently, additional roles for DNA-PK have been reported. In this review, we will describe the biochemistry, structure and function of DNA-PK, its roles in DNA double strand break repair and its newly described roles in mitosis and other cellular processes. PMID:25550082

Epidural block

Science.gov (United States)

... page: //medlineplus.gov/ency/patientinstructions/000484.htm Epidural block - pregnancy To use the sharing features on this page, please enable JavaScript. An epidural block is a numbing medicine given by injection (shot) ...

Defects in Histone H3.3 Phosphorylation and ATRX Recruitment to Misaligned Chromosomes during Mitosis Contribute to the Development of Pediatric Glioblastomas

Science.gov (United States)

2015-09-01

aneuploidy. 2. Keywords: aneuploidy, ATRX, cell cycle, chromosome missegregation, CRISPR /Cas9, DAXX, glioblastoma, histone H3.3, microinjection, mitosis...histone H3.3 with mutant constructs. We have switched from shRNA hairpins to CRISPR /Cas9 gene editing to silence both alleles of H3.3 (and an H3.3...plasmids against H3F3B. Both plasmids had the Cas9 gene and a soluble GFP reporter. The CRISPR guide sequence in one of these plasmids was 100% match

Predictability of blocking

International Nuclear Information System (INIS)

Tosi, E.; Ruti, P.; Tibaldi, S.; D'Andrea, F.

1994-01-01

Tibaldi and Molteni (1990, hereafter referred to as TM) had previously investigated operational blocking predictability by the ECMWF model and the possible relationships between model systematic error and blocking in the winter season of the Northern Hemisphere, using seven years of ECMWF operational archives of analyses and day 1 to 10 forecasts. They showed that fewer blocking episodes than in the real atmosphere were generally simulated by the model, and that this deficiency increased with increasing forecast time. As a consequence of this, a major contribution to the systematic error in the winter season was shown to derive from the inability of the model to properly forecast blocking. In this study, the analysis performed in TM for the first seven winter seasons of the ECMWF operational model is extended to the subsequent five winters, during which model development, reflecting both resolution increases and parametrisation modifications, continued unabated. In addition the objective blocking index developed by TM has been applied to the observed data to study the natural low frequency variability of blocking. The ability to simulate blocking of some climate models has also been tested

Homogeneous bilateral block shifts

Indian Academy of Sciences (India)

Douglas class were classified in [3]; they are unilateral block shifts of arbitrary block size (i.e. dim H(n) can be anything). However, no examples of irreducible homogeneous bilateral block shifts of block size larger than 1 were known until now.

Detection block

International Nuclear Information System (INIS)

Bezak, A.

1987-01-01

A diagram is given of a detection block used for monitoring burnup of nuclear reactor fuel. A shielding block is an important part of the detection block. It stabilizes the fuel assembly in the fixing hole in front of a collimator where a suitable gamma beam is defined for gamma spectrometry determination of fuel burnup. The detector case and a neutron source case are placed on opposite sides of the fixing hole. For neutron measurement for which the water in the tank is used as a moderator, the neutron detector-fuel assembly configuration is selected such that neutrons from spontaneous fission and neutrons induced with the neutron source can both be measured. The patented design of the detection block permits longitudinal travel and rotation of the fuel assembly to any position, and thus more reliable determination of nuclear fuel burnup. (E.S.). 1 fig

Antagonism between the dynein and Ndc80 complexes at kinetochores controls the stability of kinetochore-microtubule attachments during mitosis.

Science.gov (United States)

Amin, Mohammed A; McKenney, Richard J; Varma, Dileep

2018-04-20

Chromosome alignment and segregation during mitosis require kinetochore-microtubule (kMT) attachments that are mediated by the molecular motor dynein and the kMT-binding complex Ndc80. The Rod-ZW10-Zwilch (RZZ) complex is central to this coordination as it has an important role in dynein recruitment and has recently been reported to have a key function in the regulation of stable kMT attachments in Caenorhabditis elegans besides its role in activating the spindle assembly checkpoint (SAC). However, the mechanism by which these protein complexes control kMT attachments to drive chromosome motility during early mitosis is still unclear. Here, using in vitro total internal reflection fluorescence microscopy, we observed that higher concentrations of Ndc80 inhibited dynein binding to MTs, providing evidence that Ndc80 and dynein antagonize each other's function. High-resolution microscopy and siRNA-mediated functional disruption revealed that severe defects in chromosome alignment induced by depletion of dynein or the dynein adapter Spindly are rescued by codepletion of the RZZ component Rod in human cells. Interestingly, rescue of the chromosome alignment defects was independent of Rod function in SAC activation and was accompanied by a remarkable restoration of stable kMT attachments. Furthermore, the chromosome alignment rescue depended on the plus-end-directed motility of centromere protein E (CENP-E) because cells codepleted of CENP-E, Rod, and dynein could not establish stable kMT attachments or align their chromosomes properly. Our findings support the idea that dynein may control the function of the Ndc80 complex in stabilizing kMT attachments directly by interfering with Ndc80-MT binding or indirectly by controlling the Rod-mediated inhibition of Ndc80. © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.

Hypothetical physicochemical mechanisms of some intracellular processes: The hydrate hypothesis of mitosis and DNA replication

International Nuclear Information System (INIS)

Kadyshevich, E.A.; Ostrovskii, V.E.

2007-01-01

A DNA replication, mitosis, and binary fission hydrate hypothesis (MRH hypothesis) allowing non-trivial explanations for the physicochemical mechanisms of some intracellular processes is proposed. The hypothesis has a thermodynamic basis and is initiated by original experimental calorimetric and kinetic studies of the behavior of functional organic polymer and monomer substances in highly concentrated aqueous solutions. Experimental data demonstrating the occurrence of a short-range ordering in concentrated aqueous solutions of such substances are included. Hypothetical simple non-enzymatic unified mechanisms for the natural processes of DNA local unwinding preceding the start of duplication, DNA replication, formation and disappearance of the protein bonds between sister chromatids in the centromere region of eukaryotic DNA and in the centromere-like region of prokaryotic DNA, moving of daughter chromosomes apart to the opposite sides of cells in late anaphase, and formation of the nuclear envelopes in telophase and intracellular membranes between the newly formed nuclei in cytokinesis are formulated. The nature of a number of other intracellular phenomena is discussed

Cell cycle and cell death are not necessary for appressorium formation and plant infection in the fungal plant pathogen Colletotrichum gloeosporioides

Directory of Open Access Journals (Sweden)

Barhoom Sima

2008-02-01

Full Text Available Abstract Background In order to initiate plant infection, fungal spores must germinate and penetrate into the host plant. Many fungal species differentiate specialized infection structures called appressoria on the host surface, which are essential for successful pathogenic development. In the model plant pathogen Magnaporthe grisea completion of mitosis and autophagy cell death of the spore are necessary for appressoria-mediated plant infection; blocking of mitosis prevents appressoria formation, and prevention of autophagy cell death results in non-functional appressoria. Results We found that in the closely related plant pathogen Colletotrichum gloeosporioides, blocking of the cell cycle did not prevent spore germination and appressoria formation. The cell cycle always lagged behind the morphogenetic changes that follow spore germination, including germ tube and appressorium formation, differentiation of the penetrating hypha, and in planta formation of primary hyphae. Nuclear division was arrested following appressorium formation and was resumed in mature appressoria after plant penetration. Unlike in M. grisea, blocking of mitosis had only a marginal effect on appressoria formation; development in hydroxyurea-treated spores continued only for a limited number of cell divisions, but normal numbers of fully developed mature appressoria were formed under conditions that support appressoria formation. Similar results were also observed in other Colletotrichum species. Spores, germ tubes, and appressoria retained intact nuclei and remained viable for several days post plant infection. Conclusion We showed that in C. gloeosporioides the differentiation of infection structures including appressoria precedes mitosis and can occur without nuclear division. This phenomenon was also found to be common in other Colletotrichum species. Spore cell death did not occur during plant infection and the fungus primary infection structures remained viable

DFT and 3D-QSAR Studies of Anti-Cancer Agents m-(4-Morpholinoquinazolin-2-yl) Benzamide Derivatives for Novel Compounds Design

Science.gov (United States)

Zhao, Siqi; Zhang, Guanglong; Xia, Shuwei; Yu, Liangmin

2018-06-01

As a group of diversified frameworks, quinazolin derivatives displayed a broad field of biological functions, especially as anticancer. To investigate the quantitative structure-activity relationship, 3D-QSAR models were generated with 24 quinazolin scaffold molecules. The experimental and predicted pIC50 values for both training and test set compounds showed good correlation, which proved the robustness and reliability of the generated QSAR models. The most effective CoMFA and CoMSIA were obtained with correlation coefficient r 2 ncv of 1.00 (both) and leave-one-out coefficient q 2 of 0.61 and 0.59, respectively. The predictive abilities of CoMFA and CoMSIA were quite good with the predictive correlation coefficients ( r 2 pred ) of 0.97 and 0.91. In addition, the statistic results of CoMFA and CoMSIA were used to design new quinazolin molecules.

Noninvasive three-dimensional live imaging methodology for the spindles at meiosis and mitosis

Science.gov (United States)

Zheng, Jing-gao; Huo, Tiancheng; Tian, Ning; Chen, Tianyuan; Wang, Chengming; Zhang, Ning; Zhao, Fengying; Lu, Danyu; Chen, Dieyan; Ma, Wanyun; Sun, Jia-lin; Xue, Ping

2013-05-01

The spindle plays a crucial role in normal chromosome alignment and segregation during meiosis and mitosis. Studying spindles in living cells noninvasively is of great value in assisted reproduction technology (ART). Here, we present a novel spindle imaging methodology, full-field optical coherence tomography (FF-OCT). Without any dye labeling and fixation, we demonstrate the first successful application of FF-OCT to noninvasive three-dimensional (3-D) live imaging of the meiotic spindles within the mouse living oocytes at metaphase II as well as the mitotic spindles in the living zygotes at metaphase and telophase. By post-processing of the 3-D dataset obtained with FF-OCT, the important morphological and spatial parameters of the spindles, such as short and long axes, spatial localization, and the angle of meiotic spindle deviation from the first polar body in the oocyte were precisely measured with the spatial resolution of 0.7 μm. Our results reveal the potential of FF-OCT as an imaging tool capable of noninvasive 3-D live morphological analysis for spindles, which might be useful to ART related procedures and many other spindle related studies.

Synthesis of amylose-block-polystyrene rod-coil block copolymers

NARCIS (Netherlands)

Loos, Katja; Stadler, Reimund

1997-01-01

In the present communication we demonstrate the synthesis of a hybrid block copolymer based on the combination of a biopolymer (amylose) with a synthetic block (polystyrene). To obtain such materials, amino-functionalized polymers were modified with maltoheptaose moieties that serve as initiators

Paravertebral Block Plus Thoracic Wall Block versus Paravertebral Block Alone for Analgesia of Modified Radical Mastectomy: A Retrospective Cohort Study.

Directory of Open Access Journals (Sweden)

Nai-Liang Li

Full Text Available Paravertebral block placement was the main anesthetic technique for modified radical mastectomy in our hospital until February 2014, when its combination with blocks targeting the pectoral musculature was initiated. We compared the analgesic effects of paravertebral blocks with or without blocks targeting the pectoral musculature for modified radical mastectomy.We retrospectively collected data from a single surgeon and anesthesiologist from June 1, 2012, to May 31, 2015. Intraoperative sedatives and analgesic requirements, time to the first analgesic request, postoperative analgesic doses, patient satisfaction, and complications were compared.Fifty-four patients received a paravertebral block alone (PECS 0, and 46 received a paravertebral block combined with blocks targeting the pectoral musculature (PECS 1. The highest intraoperative effect-site concentration of propofol was significantly lower in the PECS 1 group than in the PECS 0 group [2.3 (1.5, 2.8 vs 2.5 (1.5, 4 μg/mL, p = 0.0014]. The intraoperative rescue analgesic dose was significantly lower in the PECS 1 group [0 (0, 25 vs 0 (0, 75 mg of ketamine, p = 0.0384]. Furthermore, the PECS 1 group had a significantly longer time to the first analgesic request [636.5 (15, 720 vs 182.5 (14, 720 min, p = 0.0001]. After further adjustment for age, body mass index, American Society of Anesthesiologists Physical Status classification, chronic pain history, incidence of a superficial cervical plexus block placement, and operation duration, blocks targeting the pectoral musculature were determined to be the only significant factor (hazard ratio, 0.36; 95% confidence interval, 0.23-0.58; p < 0.0001. Very few patients used potent analgesics including morphine and ketorolac; the cumulative use of morphine or ketorolac was similar in the study groups. However, the incidence of all analgesic use, namely morphine, ketorolac, acetaminophen, and celecoxib, was significantly lower in the PECS 1 group [3

Influence of anchor block size on the thickness of adsorbed block copolymer layers

NARCIS (Netherlands)

Belder, G.F; ten Brinke, G.; Hadziioannou, G

1997-01-01

We present surface force data on three different polystyrene/poly(2-vinylpyridine) block copolymers (PS/P2VP) with a fixed size of the nonadsorbing PS block but widely varying sizes of the adsorbing P2VP block. With respect to the sizes of the two blocks, they range from moderately to highly

Combined KHFAC + DC nerve block without onset or reduced nerve conductivity after block

Science.gov (United States)

Franke, Manfred; Vrabec, Tina; Wainright, Jesse; Bhadra, Niloy; Bhadra, Narendra; Kilgore, Kevin

2014-10-01

Objective. Kilohertz frequency alternating current (KHFAC) waveforms have been shown to provide peripheral nerve conductivity block in many acute and chronic animal models. KHFAC nerve block could be used to address multiple disorders caused by neural over-activity, including blocking pain and spasticity. However, one drawback of KHFAC block is a transient activation of nerve fibers during the initiation of the nerve block, called the onset response. The objective of this study is to evaluate the feasibility of using charge balanced direct current (CBDC) waveforms to temporarily block motor nerve conductivity distally to the KHFAC electrodes to mitigate the block onset-response. Approach. A total of eight animals were used in this study. A set of four animals were used to assess feasibility and reproducibility of a combined KHFAC + CBDC block. A following randomized study, conducted on a second set of four animals, compared the onset response resulting from KHFAC alone and combined KHFAC + CBDC waveforms. To quantify the onset, peak forces and the force-time integral were measured during KHFAC block initiation. Nerve conductivity was monitored throughout the study by comparing muscle twitch forces evoked by supra-maximal stimulation proximal and distal to the block electrodes. Each animal of the randomized study received at least 300 s (range: 318-1563 s) of cumulative dc to investigate the impact of combined KHFAC + CBDC on nerve viability. Main results. The peak onset force was reduced significantly from 20.73 N (range: 18.6-26.5 N) with KHFAC alone to 0.45 N (range: 0.2-0.7 N) with the combined CBDC and KHFAC block waveform (p conductivity was observed after application of the combined KHFAC + CBDC block relative to KHFAC waveforms. Significance. The distal application of CBDC can significantly reduce or even completely prevent the KHFAC onset response without a change in nerve conductivity.

Abdominal wall blocks in adults

DEFF Research Database (Denmark)

Børglum, Jens; Gögenür, Ismail; Bendtsen, Thomas F

2016-01-01

been introduced with success. Future research should also investigate the effect of specific abdominal wall blocks on neuroendocrine and inflammatory stress response after surgery.  Summary USG abdominal wall blocks in adults are commonplace techniques today. Most abdominal wall blocks are assigned......Purpose of review Abdominal wall blocks in adults have evolved much during the last decade; that is, particularly with the introduction of ultrasound-guided (USG) blocks. This review highlights recent advances of block techniques within this field and proposes directions for future research.......  Recent findings Ultrasound guidance is now considered the golden standard for abdominal wall blocks in adults, even though some landmark-based blocks are still being investigated. The efficiency of USG transversus abdominis plane blocks in relation to many surgical procedures involving the abdominal wall...

Comparative study between ultrasound guided TAP block and paravertebral block in upper abdominal surgeries

Directory of Open Access Journals (Sweden)

Ruqaya M Elsayed Goda

2017-01-01

Conclusion: We concluded that ultrasound guided transverses abdominis plane block and thoracic paravertebral block were safe and effective anesthetic technique for upper abdominal surgery with longer and potent postoperative analgesia in thoracic paravertebral block than transverses abdominis block.

Fermion-scalar conformal blocks

Energy Technology Data Exchange (ETDEWEB)

Iliesiu, Luca [Joseph Henry Laboratories, Princeton University,Washington Road, Princeton, NJ 08544 (United States); Kos, Filip [Department of Physics, Yale University,217 Prospect Street, New Haven, CT 06520 (United States); Poland, David [Department of Physics, Yale University,217 Prospect Street, New Haven, CT 06520 (United States); School of Natural Sciences, Institute for Advanced Study,1 Einstein Dr, Princeton, New Jersey 08540 (United States); Pufu, Silviu S. [Joseph Henry Laboratories, Princeton University,Washington Road, Princeton, NJ 08544 (United States); Simmons-Duffin, David [School of Natural Sciences, Institute for Advanced Study,1 Einstein Dr, Princeton, New Jersey 08540 (United States); Yacoby, Ran [Joseph Henry Laboratories, Princeton University,Washington Road, Princeton, NJ 08544 (United States)

2016-04-13

We compute the conformal blocks associated with scalar-scalar-fermion-fermion 4-point functions in 3D CFTs. Together with the known scalar conformal blocks, our result completes the task of determining the so-called ‘seed blocks’ in three dimensions. Conformal blocks associated with 4-point functions of operators with arbitrary spins can now be determined from these seed blocks by using known differential operators.

Block Cipher Analysis

DEFF Research Database (Denmark)

Miolane, Charlotte Vikkelsø

ensurethat no attack violatesthe securitybounds specifiedbygeneric attack namely exhaustivekey search and table lookup attacks. This thesis contains a general introduction to cryptography with focus on block ciphers and important block cipher designs, in particular the Advanced Encryption Standard(AES...... on small scale variants of AES. In the final part of the thesis we present a new block cipher proposal Present and examine its security against algebraic and differential cryptanalysis in particular....

Main-chain supramolecular block copolymers.

Science.gov (United States)

Yang, Si Kyung; Ambade, Ashootosh V; Weck, Marcus

2011-01-01

Block copolymers are key building blocks for a variety of applications ranging from electronic devices to drug delivery. The material properties of block copolymers can be tuned and potentially improved by introducing noncovalent interactions in place of covalent linkages between polymeric blocks resulting in the formation of supramolecular block copolymers. Such materials combine the microphase separation behavior inherent to block copolymers with the responsiveness of supramolecular materials thereby affording dynamic and reversible materials. This tutorial review covers recent advances in main-chain supramolecular block copolymers and describes the design principles, synthetic approaches, advantages, and potential applications.

Ultrasound guided supraclavicular block.

LENUS (Irish Health Repository)

Hanumanthaiah, Deepak

2013-09-01

Ultrasound guided regional anaesthesia is becoming increasingly popular. The supraclavicular block has been transformed by ultrasound guidance into a potentially safe superficial block. We reviewed the techniques of performing supraclavicular block with special focus on ultrasound guidance.

Adductor Canal Block versus Femoral Nerve Block and Quadriceps Strength

DEFF Research Database (Denmark)

Jæger, Pia Therese; Nielsen, Zbigniew Jerzy Koscielniak; Henningsen, Lene Marianne

2013-01-01

: The authors hypothesized that the adductor canal block (ACB), a predominant sensory blockade, reduces quadriceps strength compared with placebo (primary endpoint, area under the curve, 0.5-6 h), but less than the femoral nerve block (FNB; secondary endpoint). Other secondary endpoints were...

Asymmetric PS-block-(PS-co-PB)-block-PS block copolymers: morphology formation and deformation behaviour

International Nuclear Information System (INIS)

Adhikari, Rameshwar; Huy, Trinh An; Buschnakowski, Matthias; Michler, Goerg H; Knoll, Konrad

2004-01-01

Morphology formation and deformation behaviour of asymmetric styrene/butadiene triblock copolymers (total polystyrene (PS) content ∼70%) consisting of PS outer blocks held apart by a styrene-co-butadiene random copolymer block (PS-co-PB) each were investigated. The techniques used were differential scanning calorimetry, transmission electron microscopy, uniaxial tensile testing and Fourier-transform infrared spectroscopy. A significant shift of the phase behaviour relative to that of a neat symmetric triblock copolymer was observed, which can be attributed to the asymmetric architecture and the presence of PS-co-PB as a soft block. The mechanical properties and the microdeformation phenomena were mainly controlled by the nature of their solid-state morphology. Independent of morphology type, the soft phase was found to deform to a significantly higher degree of orientation when compared with the hard phase

Adductor canal block versus femoral nerve block for analgesia after total knee arthroplasty

DEFF Research Database (Denmark)

Jaeger, Pia; Zaric, Dusanka; Fomsgaard, Jonna Storm

2013-01-01

Femoral nerve block (FNB), a commonly used postoperative pain treatment after total knee arthroplasty (TKA), reduces quadriceps muscle strength essential for mobilization. In contrast, adductor canal block (ACB) is predominately a sensory nerve block. We hypothesized that ACB preserves quadriceps...

Suramin blocks interaction between human FGF1 and FGFR2 D2 domain and reduces downstream signaling activity

Energy Technology Data Exchange (ETDEWEB)

Wu, Zong-Sian, E-mail: gary810426@hotmail.com [Department of Chemistry, National Tsing Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China); Liu, Che Fu, E-mail: s9823002@m98.nthu.edu.tw [Department of Chemistry, National Tsing Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China); Fu, Brian, E-mail: brianfu9@gmail.com [Northwood High School, Irvine, CA (United States); Chou, Ruey-Hwang, E-mail: rhchou@mail.cmu.edu.tw [Graduate Institute of Cancer Biology and Center for Molecular Medicine, China Medical University, No.91, Hsueh-Shih Road, Taichung 40402, Taiwan (China); Department of Biotechnology, Asia University, Taiwan (China); Yu, Chin, E-mail: cyu.nthu@gmail.com [Department of Chemistry, National Tsing Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China)

2016-09-02

The extracellular portion of the human fibroblast growth factor receptor2 D2 domain (FGFR2 D2) interacts with human fibroblast growth factor 1 (hFGF1) to activate a downstream signaling cascade that ultimately affects mitosis and differentiation. Suramin is an antiparasiticdrug and a potent inhibitor of FGF-induced angiogenesis. Suramin has been shown to bind to hFGF1, and might block the interaction between hFGF1 and FGFR2 D2. Here, we titrated hFGF1 with FGFR2 D2 and suramin to elucidate their interactions using the detection of NMR. The docking results of both hFGF1-FGFR2 D2 domain and hFGF1-suramin complex were superimposed. The results indicate that suramin blocks the interaction between hFGF1 and FGFR2 D2. We used the PyMOL software to show the hydrophobic interaction of hFGF1-suramin. In addition, we used a Water-soluble Tetrazolium salts assay (WST1) to assess hFGF1 bioactivity. The results will be useful for the development of new antimitogenic activity drugs. - Highlights: • The interfacial residues on hFGF1-FGFR2 D2 and hFGF1-Suramin contact surface were mapped by {sup 1}H-{sup 15}N HSQC experiments. • hFGF1-FGFR2 D2 and hFGF1-Suramin complex models were generated from NMR restraints by using HADDOCK program. • We analyzed hFGF1-Suramin complex models and found the interaction between hFGF1-Suramin is hydrophobic. • The bioactivity of the hFGF1-FGFR2 D2 and hFGF1-Suramin complex was studied by using WST1 assay.

Suramin blocks interaction between human FGF1 and FGFR2 D2 domain and reduces downstream signaling activity

International Nuclear Information System (INIS)

Wu, Zong-Sian; Liu, Che Fu; Fu, Brian; Chou, Ruey-Hwang; Yu, Chin

2016-01-01

The extracellular portion of the human fibroblast growth factor receptor2 D2 domain (FGFR2 D2) interacts with human fibroblast growth factor 1 (hFGF1) to activate a downstream signaling cascade that ultimately affects mitosis and differentiation. Suramin is an antiparasiticdrug and a potent inhibitor of FGF-induced angiogenesis. Suramin has been shown to bind to hFGF1, and might block the interaction between hFGF1 and FGFR2 D2. Here, we titrated hFGF1 with FGFR2 D2 and suramin to elucidate their interactions using the detection of NMR. The docking results of both hFGF1-FGFR2 D2 domain and hFGF1-suramin complex were superimposed. The results indicate that suramin blocks the interaction between hFGF1 and FGFR2 D2. We used the PyMOL software to show the hydrophobic interaction of hFGF1-suramin. In addition, we used a Water-soluble Tetrazolium salts assay (WST1) to assess hFGF1 bioactivity. The results will be useful for the development of new antimitogenic activity drugs. - Highlights: • The interfacial residues on hFGF1-FGFR2 D2 and hFGF1-Suramin contact surface were mapped by "1H-"1"5N HSQC experiments. • hFGF1-FGFR2 D2 and hFGF1-Suramin complex models were generated from NMR restraints by using HADDOCK program. • We analyzed hFGF1-Suramin complex models and found the interaction between hFGF1-Suramin is hydrophobic. • The bioactivity of the hFGF1-FGFR2 D2 and hFGF1-Suramin complex was studied by using WST1 assay.

Block That Pain!

Science.gov (United States)

Skip Navigation Bar Home Current Issue Past Issues Block That Pain! Past Issues / Fall 2007 Table of ... contrast, most pain relievers used for surgical procedures block activity in all types of neurons. This can ...

Bundle Branch Block

Science.gov (United States)

... known cause. Causes can include: Left bundle branch block Heart attacks (myocardial infarction) Thickened, stiffened or weakened ... myocarditis) High blood pressure (hypertension) Right bundle branch block A heart abnormality that's present at birth (congenital) — ...

A 2D/3D image analysis system to track fluorescently labeled structures in rod-shaped cells: application to measure spindle pole asymmetry during mitosis.

Science.gov (United States)

Schmitter, Daniel; Wachowicz, Paulina; Sage, Daniel; Chasapi, Anastasia; Xenarios, Ioannis; Simanis; Unser, Michael

2013-01-01

The yeast Schizosaccharomyces pombe is frequently used as a model for studying the cell cycle. The cells are rod-shaped and divide by medial fission. The process of cell division, or cytokinesis, is controlled by a network of signaling proteins called the Septation Initiation Network (SIN); SIN proteins associate with the SPBs during nuclear division (mitosis). Some SIN proteins associate with both SPBs early in mitosis, and then display strongly asymmetric signal intensity at the SPBs in late mitosis, just before cytokinesis. This asymmetry is thought to be important for correct regulation of SIN signaling, and coordination of cytokinesis and mitosis. In order to study the dynamics of organelles or large protein complexes such as the spindle pole body (SPB), which have been labeled with a fluorescent protein tag in living cells, a number of the image analysis problems must be solved; the cell outline must be detected automatically, and the position and signal intensity associated with the structures of interest within the cell must be determined. We present a new 2D and 3D image analysis system that permits versatile and robust analysis of motile, fluorescently labeled structures in rod-shaped cells. We have designed an image analysis system that we have implemented as a user-friendly software package allowing the fast and robust image-analysis of large numbers of rod-shaped cells. We have developed new robust algorithms, which we combined with existing methodologies to facilitate fast and accurate analysis. Our software permits the detection and segmentation of rod-shaped cells in either static or dynamic (i.e. time lapse) multi-channel images. It enables tracking of two structures (for example SPBs) in two different image channels. For 2D or 3D static images, the locations of the structures are identified, and then intensity values are extracted together with several quantitative parameters, such as length, width, cell orientation, background fluorescence and

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

Directory of Open Access Journals (Sweden)

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.

The conversion of centrioles to centrosomes: essential coupling of duplication with segregation.

Science.gov (United States)

Wang, Won-Jing; Soni, Rajesh Kumar; Uryu, Kunihiro; Tsou, Meng-Fu Bryan

2011-05-16

Centrioles are self-reproducing organelles that form the core structure of centrosomes or microtubule-organizing centers (MTOCs). However, whether duplication and MTOC organization reflect innate activities of centrioles or activities acquired conditionally is unclear. In this paper, we show that newly formed full-length centrioles had no inherent capacity to duplicate or to organize pericentriolar material (PCM) but acquired both after mitosis through a Plk1-dependent modification that occurred in early mitosis. Modified centrioles initiated PCM recruitment in G1 and segregated equally in mitosis through association with spindle poles. Conversely, unmodified centrioles segregated randomly unless passively tethered to modified centrioles. Strikingly, duplication occurred only in centrioles that were both modified and disengaged, whereas unmodified centrioles, engaged or not, were "infertile," indicating that engagement specifically blocks modified centrioles from reduplication. These two requirements, centriole modification and disengagement, fully exclude unlimited duplication in one cell cycle. We thus uncovered a Plk1-dependent mechanism whereby duplication and segregation are coupled to maintain centriole homeostasis.

A randomized trial comparing surgeon-administered intraoperative transversus abdominis plane block with anesthesiologist-administered transcutaneous block.

Science.gov (United States)

Narasimhulu, D M; Scharfman, L; Minkoff, H; George, B; Homel, P; Tyagaraj, K

2018-04-27

Injection of local anesthetic into the transversus abdominis plane (TAP block) decreases systemic morphine requirements after abdominal surgery. We compared intraoperative surgeon-administered TAP block (surgical TAP) to anesthesiologist-administered transcutaneous ultrasound-guided TAP block (conventional TAP) for post-cesarean analgesia. We hypothesized that surgical TAP blocks would take less time to perform than conventional TAP blocks. We performed a randomized trial, recruiting 41 women undergoing cesarean delivery under neuraxial anesthesia, assigning them to either surgical TAP block (n=20) or conventional TAP block (n=21). Time taken to perform the block was the primary outcome, while postoperative pain scores and 24-hour opioid requirements were secondary outcomes. Student's t-test was used to compare block time and Kruskal-Wallis test opioid consumption and pain-scores. Time taken to perform the block (2.4 vs 12.1 min, P consumption (P=0.17) and postoperative pain scores at 4, 8, 24 and 48 h were not significantly different between the groups. Surgical TAP blocks are feasible and less time consuming than conventional TAP blocks, while providing comparable analgesia after cesarean delivery. Copyright © 2018 Elsevier Ltd. All rights reserved.

Thinking Outside the Block: An Innovative Alternative to 4X4 Block Scheduling.

Science.gov (United States)

Frank, Myra

2002-01-01

Introduces a 4x1 block scheduling method that was developed as an alternative to 4x4 block scheduling. Schedules Fridays for summer school, test preparation, and enrichment and elective courses. Includes suggestions on how to alleviate drawbacks of the 4x1 block schedule. (YDS)

Distribution of short block copolymer chains in Binary Blends of Block Copolymers Having Hydrogen Bonding

Science.gov (United States)

Kwak, Jongheon; Han, Sunghyun; Kim, Jin Kon

2014-03-01

A binary mixture of two block copolymers whose blocks are capable of forming the hydrogen bonding allows one to obtain various microdomains that could not be expected for neat block copolymer. For instance, the binary blend of symmetric polystyrene-block-poly(2-vinylpyridine) copolymer (PS-b-P2VP) and polystyrene-block-polyhydroxystyrene copolymer (PS-b-PHS) blends where the hydrogen bonding occurred between P2VP and PHS showed hexagonally packed (HEX) cylindrical and body centered cubic (BCC) spherical microdomains. To know the exact location of short block copolymer chains at the interface, we synthesized deuterated polystyrene-block-polyhydroxystyrene copolymer (dPS-b-PHS) and prepared a binary mixture with PS-b-P2VP. We investigate, via small angle X-ray scattering (SAXS) and neutron reflectivity (NR), the exact location of shorter dPS block chain near the interface of the microdomains.

Minimum Description Length Block Finder, a Method to Identify Haplotype Blocks and to Compare the Strength of Block Boundaries

OpenAIRE

Mannila, H.; Koivisto, M.; Perola, M.; Varilo, T.; Hennah, W.; Ekelund, J.; Lukk, M.; Peltonen, L.; Ukkonen, E.

2003-01-01

We describe a new probabilistic method for finding haplotype blocks that is based on the use of the minimum description length (MDL) principle. We give a rigorous definition of the quality of a segmentation of a genomic region into blocks and describe a dynamic programming algorithm for finding the optimal segmentation with respect to this measure. We also describe a method for finding the probability of a block boundary for each pair of adjacent markers: this gives a tool for evaluating the ...

The wild tapered block bootstrap

DEFF Research Database (Denmark)

Hounyo, Ulrich

In this paper, a new resampling procedure, called the wild tapered block bootstrap, is introduced as a means of calculating standard errors of estimators and constructing confidence regions for parameters based on dependent heterogeneous data. The method consists in tapering each overlapping block...... of the series first, the applying the standard wild bootstrap for independent and heteroscedastic distrbuted observations to overlapping tapered blocks in an appropriate way. Its perserves the favorable bias and mean squared error properties of the tapered block bootstrap, which is the state-of-the-art block......-order asymptotic validity of the tapered block bootstrap as well as the wild tapered block bootstrap approximation to the actual distribution of the sample mean is also established when data are assumed to satisfy a near epoch dependent condition. The consistency of the bootstrap variance estimator for the sample...

Dynamin inhibitors induce caspase-mediated apoptosis following cytokinesis failure in human cancer cells and this is blocked by Bcl-2 overexpression

Directory of Open Access Journals (Sweden)

Braithwaite Antony W

2011-06-01

Full Text Available Abstract Background The aim of both classical (e.g. taxol and targeted anti-mitotic agents (e.g. Aurora kinase inhibitors is to disrupt the mitotic spindle. Such compounds are currently used in the clinic and/or are being tested in clinical trials for cancer treatment. We recently reported a new class of targeted anti-mitotic compounds that do not disrupt the mitotic spindle, but exclusively block completion of cytokinesis. This new class includes MiTMAB and OcTMAB (MiTMABs, which are potent inhibitors of the endocytic protein, dynamin. Like other anti-mitotics, MiTMABs are highly cytotoxic and possess anti-proliferative properties, which appear to be selective for cancer cells. The cellular response following cytokinesis failure and the mechanistic pathway involved is unknown. Results We show that MiTMABs induce cell death specifically following cytokinesis failure via the intrinsic apoptotic pathway. This involves cleavage of caspase-8, -9, -3 and PARP, DNA fragmentation and membrane blebbing. Apoptosis was blocked by the pan-caspase inhibitor, ZVAD, and in HeLa cells stably expressing the anti-apoptotic protein, Bcl-2. This resulted in an accumulation of polyploid cells. Caspases were not cleaved in MiTMAB-treated cells that did not enter mitosis. This is consistent with the model that apoptosis induced by MiTMABs occurs exclusively following cytokinesis failure. Cytokinesis failure induced by cytochalasin B also resulted in apoptosis, suggesting that disruption of this process is generally toxic to cells. Conclusion Collectively, these data indicate that MiTMAB-induced apoptosis is dependent on both polyploidization and specific intracellular signalling components. This suggests that dynamin and potentially other cytokinesis factors are novel targets for development of cancer therapeutics.

Paroxysmal atrioventricular block: Electrophysiological mechanism of phase 4 conduction block in the His-Purkinje system: A comparison with phase 3 block.

Science.gov (United States)

Shenasa, Mohammad; Josephson, Mark E; Wit, Andrew L

2017-11-01

Paroxysmal atrioventricular (A-V) block is relatively rare, and due to its transient nature, it is often under recognized. It is often triggered by atrial, junctional, or ventricular premature beats, and occurs in the presence of a diseased His-Purkinje system (HPS). Here, we present a 45-year-old white male who was admitted for observation due to recurrent syncope and near-syncope, who had paroxysmal A-V block. The likely cellular electrophysiological mechanisms(s) of paroxysmal A-V block and its differential diagnosis and management are discussed. Continuous electrocardiographic monitoring was done while the patient was in the cardiac unit. Multiple episodes of paroxysmal A-V block were documented in this case. All episodes were initiated and terminated with atrial/junctional premature beats. The patient underwent permanent pacemaker implantation and has remained asymptomatic since then. Paroxysmal A-V block is rare and often causes syncope or near-syncope. Permanent pacemaker implantation is indicated according to the current guidelines. Paroxysmal A-V block occurs in the setting of diseased HPS and is bradycardia-dependent. The detailed electrophysiological mechanisms, which involve phase 4 diastolic depolarization, and differential diagnosis are discussed. © 2017 Wiley Periodicals, Inc.

Designers Block 2002

DEFF Research Database (Denmark)

Dickson, Thomas

2002-01-01

Artiklen indleder med: ved siden aaf Londons etablerede designmesse '100% Design', er der vokset et undergrundsmiljø af designudstillinger op. Det dominerende og mest kendte initiativ er Designers Block, der i år udstillede to steder i byen. Designers Block er et mere uformelt udstillingsforum...

NLRP3 activation and mitosis are mutually exclusive events coordinated by NEK7, a new inflammasome component.

Science.gov (United States)

Shi, Hexin; Wang, Ying; Li, Xiaohong; Zhan, Xiaoming; Tang, Miao; Fina, Maggy; Su, Lijing; Pratt, David; Bu, Chun Hui; Hildebrand, Sara; Lyon, Stephen; Scott, Lindsay; Quan, Jiexia; Sun, Qihua; Russell, Jamie; Arnett, Stephanie; Jurek, Peter; Chen, Ding; Kravchenko, Vladimir V; Mathison, John C; Moresco, Eva Marie Y; Monson, Nancy L; Ulevitch, Richard J; Beutler, Bruce

2016-03-01

The NLRP3 inflammasome responds to microbes and danger signals by processing and activating proinflammatory cytokines, including interleukin 1β (IL-1β) and IL-18. We found here that activation of the NLRP3 inflammasome was restricted to interphase of the cell cycle by NEK7, a serine-threonine kinase previously linked to mitosis. Activation of the NLRP3 inflammasome required NEK7, which bound to the leucine-rich repeat domain of NLRP3 in a kinase-independent manner downstream of the induction of mitochondrial reactive oxygen species (ROS). This interaction was necessary for the formation of a complex containing NLRP3 and the adaptor ASC, oligomerization of ASC and activation of caspase-1. NEK7 promoted the NLRP3-dependent cellular inflammatory response to intraperitoneal challenge with monosodium urate and the development of experimental autoimmune encephalitis in mice. Our findings suggest that NEK7 serves as a cellular switch that enforces mutual exclusivity of the inflammasome response and cell division.

Zika Virus Disrupts Phospho-TBK1 Localization and Mitosis in Human Neuroepithelial Stem Cells and Radial Glia

Directory of Open Access Journals (Sweden)

Marco Onorati

2016-09-01

Full Text Available The mechanisms underlying Zika virus (ZIKV-related microcephaly and other neurodevelopment defects remain poorly understood. Here, we describe the derivation and characterization, including single-cell RNA-seq, of neocortical and spinal cord neuroepithelial stem (NES cells to model early human neurodevelopment and ZIKV-related neuropathogenesis. By analyzing human NES cells, organotypic fetal brain slices, and a ZIKV-infected micrencephalic brain, we show that ZIKV infects both neocortical and spinal NES cells as well as their fetal homolog, radial glial cells (RGCs, causing disrupted mitoses, supernumerary centrosomes, structural disorganization, and cell death. ZIKV infection of NES cells and RGCs causes centrosomal depletion and mitochondrial sequestration of phospho-TBK1 during mitosis. We also found that nucleoside analogs inhibit ZIKV replication in NES cells, protecting them from ZIKV-induced pTBK1 relocalization and cell death. We established a model system of human neural stem cells to reveal cellular and molecular mechanisms underlying neurodevelopmental defects associated with ZIKV infection and its potential treatment.

Opportunities for measuring DNA synthesis time by quantitative autoradiography

International Nuclear Information System (INIS)

Vasileva, D.

1980-01-01

DNA sysntesis time (Tsub(s)) in cells of the canine erythropoiesis and myelopoiesis pools was determined by quantitative autoradiography according to Doermer. In contrast to mitosis labelling for Tsub(s) estimation as so far applied, this technique uses well-differentiated cells. After blocking endogeneous DNA synthesis with 5-fluorodeoxyuridine, its further course becomes dependent on exogeneous supply of thymidine, in the form of 14 C-thymidine. From incroporation of the latter into the individual cell within a definite time span (3-7 min) and taking into account its total amount, Tsub(s) may be calculated. The data thus obtained were found to agree with Tsub(s) values as estimated from the labelled mitosis curve

Zeatin is indispensable for the G2-M transition in tobacco BY-2 cells.

Science.gov (United States)

Laureys, F; Dewitte, W; Witters, E; Van Montagu, M; Inzé, D; Van Onckelen, H

1998-04-10

The importance of N6-isoprenoid cytokinins in the G2-M transition of Nicotiana tabacum BY-2 cells was investigated. Both cytokinin biosynthesis and entry in mitosis were partially blocked by application at early or late G2 of lovastatin (10 microM), an inhibitor of mevalonic acid synthesis. LC-MS/MS quantification of endogenous cytokinins proved that lovastatin affects cytokinin biosynthesis by inhibiting HMG-CoA reductase. Out of eight different aminopurines and a synthetic auxin tested for their ability to override lovastatin inhibition of mitosis, only zeatin was active. Our data point to a key role for a well-defined cytokinin (here, zeatin) in the G2-M transition of tobacco BY-2 cells.

Arthroscopic medial meniscus trimming or repair under nerve blocks: Which nerves should be blocked?

Science.gov (United States)

Taha, AM; Abd-Elmaksoud, AM

2016-01-01

Background: This study aimed to determine the role of the sciatic and obturator nerve blocks (in addition to femoral block) in providing painless arthroscopic medial meniscus trimming/repair. Materials and Methods: One hundred and twenty patients with medial meniscus tear, who had been scheduled to knee arthroscopy, were planned to be included in this controlled prospective double-blind study. The patients were randomly allocated into three equal groups; FSO, FS, and FO. The femoral, sciatic, and obturator nerves were blocked in FSO groups. The femoral and sciatic nerves were blocked in FS group, while the femoral and obturator nerves were blocked in FO group. Intraoperative pain and its causative surgical maneuver were recorded. Results: All the patients (n = 7, 100%) in FO group had intraoperative pain. The research was terminated in this group but completed in FS and FSO groups (40 patients each). During valgus positioning of the knee for surgical management of the medial meniscus tear, the patients in FS group experienced pain more frequently than those in FSO group (P = 0.005). Conclusion: Adding a sciatic nerve block to the femoral nerve block is important for painless knee arthroscopy. Further adding of an obturator nerve block may be needed when a valgus knee position is required to manage the medial meniscus tear. PMID:27375382

Coastal protection using topological interlocking blocks

Science.gov (United States)

Pasternak, Elena; Dyskin, Arcady; Pattiaratchi, Charitha; Pelinovsky, Efim

2013-04-01

The coastal protection systems mainly rely on the self-weight of armour blocks to ensure its stability. We propose a system of interlocking armour blocks, which form plate-shape assemblies. The shape and the position of the blocks are chosen in such a way as to impose kinematic constraints that prevent the blocks from being removed from the assembly. The topological interlocking shapes include simple convex blocks such as platonic solids, the most practical being tetrahedra, cubes and octahedra. Another class of topological interlocking blocks is so-called osteomorphic blocks, which form plate-like assemblies tolerant to random block removal (almost 25% of blocks need to be removed for the assembly to loose integrity). Both classes require peripheral constraint, which can be provided either by the weight of the blocks or post-tensioned internal cables. The interlocking assemblies provide increased stability because lifting one block involves lifting (and bending) the whole assembly. We model the effect of interlocking by introducing an equivalent additional self-weight of the armour blocks. This additional self-weight is proportional to the critical pressure needed to cause bending of the interlocking assembly when it loses stability. Using beam approximation we find an equivalent stability coefficient for interlocking. It is found to be greater than the stability coefficient of a structure with similar blocks without interlocking. In the case when the peripheral constraint is provided by the weight of the blocks and for the slope angle of 45o, the effective stability coefficient for a structure of 100 blocks is 33% higher than the one for a similar structure without interlocking. Further increase in the stability coefficient can be reached by a specially constructed peripheral constraint system, for instance by using post-tension cables.

Nalbuphine as an adjuvant to 0.25% levobupivacaine in ultrasound-guided supraclavicular block provided prolonged sensory block and similar motor block durations (RCT).

Science.gov (United States)

Abdelhamid, Bassant Mohamed; Omar, Heba

2018-05-28

Prolonged postoperative analgesia with early motor recovery for early rehabilitation is a challenge in regional block. The purpose of this study is to evaluate the effect of adding 20 mg nalbuphine to 25 ml of 0.25% levobupivacaine in supraclavicular brachial plexus block. One hundred thirty-five (135) patients scheduled for hand and forearm surgeries with supraclavicular block were randomly allocated into three equal groups. Group L received 25 ml of 0.5% levobupivacaine + 1 ml normal saline; group H received 25 ml of 0.25% levobupivacaine + 1 ml normal saline; and group N received 25 ml of 0.25% levobupivacaine + 1 ml (20 mg) nalbuphine. Onset time and duration of sensory and motor block, and time to first analgesic dose were recorded. Sensory block onset was comparable between the three groups. Motor block onset in group L and group N was comparable (13.16 ± 3.07 and 13.84 ± 3.05 min, respectively) and was shorter than that in group H (15.71 ± 2 0.91 min). Sensory block duration in group L and group N was comparable (522.22 ± 69.57 and 533.78 ± 66.03 min, respectively) and was longer than that in group H (342.67 ± 92.80 min). Motor block duration in group N and group H was comparable (272.00 ± 59.45 and 249.78 ± 66.01 min, respectively) and was shorter than that in group L (334.67 ± 57.90 min). Time to first analgesic dose was significantly longer in group N (649.78 ± 114.76 min) than that of group L and group H (575.56 ± 96.85 and 375.56 ± 84.49 min, respectively) and longer in group L when compared to group H. Adding 20 mg nalbuphine to 25 ml of 0.25% levobupivacaine in supraclavicular block provided prolonged duration of sensory block with similar duration of motor block.

The Cell Cycle Timing of Centromeric Chromatin Assembly in Drosophila Meiosis Is Distinct from Mitosis Yet Requires CAL1 and CENP-C

Science.gov (United States)

Gorgescu, Walter; Tang, Jonathan; Costes, Sylvain V.; Karpen, Gary H.

2012-01-01

CENP-A (CID in flies) is the histone H3 variant essential for centromere specification, kinetochore formation, and chromosome segregation during cell division. Recent studies have elucidated major cell cycle mechanisms and factors critical for CENP-A incorporation in mitosis, predominantly in cultured cells. However, we do not understand the roles, regulation, and cell cycle timing of CENP-A assembly in somatic tissues in multicellular organisms and in meiosis, the specialized cell division cycle that gives rise to haploid gametes. Here we investigate the timing and requirements for CID assembly in mitotic tissues and male and female meiosis in Drosophila melanogaster, using fixed and live imaging combined with genetic approaches. We find that CID assembly initiates at late telophase and continues during G1 phase in somatic tissues in the organism, later than the metaphase assembly observed in cultured cells. Furthermore, CID assembly occurs at two distinct cell cycle phases during male meiosis: prophase of meiosis I and after exit from meiosis II, in spermatids. CID assembly in prophase I is also conserved in female meiosis. Interestingly, we observe a novel decrease in CID levels after the end of meiosis I and before meiosis II, which correlates temporally with changes in kinetochore organization and orientation. We also demonstrate that CID is retained on mature sperm despite the gross chromatin remodeling that occurs during protamine exchange. Finally, we show that the centromere proteins CAL1 and CENP-C are both required for CID assembly in meiosis and normal progression through spermatogenesis. We conclude that the cell cycle timing of CID assembly in meiosis is different from mitosis and that the efficient propagation of CID through meiotic divisions and on sperm is likely to be important for centromere specification in the developing zygote. PMID:23300382

Approximate design theory for a simple block design with random block effects

OpenAIRE

Christof, Karin

1985-01-01

Approximate design theory for a simple block design with random block effects / K. Christof ; F. Pukelsheim. - In: Linear statistical inference / ed. by T. Calinski ... - Berlin u. a. : Springer, 1985. - S. 20-28. - (Lecture notes in statistics ; 35)

Positioning of the NOR-bearing chromosomes in relation to nucleoli in daughter cells after mitosis.

Science.gov (United States)

Kalmárová, M; Smirnov, E; Kovácik, L; Popov, A; Raska, I

2008-01-01

It is known that chromosomes occupy non-random positions in the cell nucleus. However, it is not clear to what extent their nuclear positions, together with their neighborhood, are conserved in daughter cells. To address specific aspects of this problem, we used the model of the chromosomes carrying ribosomal genes that are organized in clusters termed Nucleolus Organizer Regions (NORs). We compared the association of chosen NOR-bearing chromosomes (NOR-chromosomes) with nucleoli, as well as the numbers of nucleoli, in the pairs of daughter cells, and established how frequently the daughter cells had equal numbers of the homologs of certain NOR-chromosomes associated with individual nucleoli. The daughter cells typically had different numbers of nucleoli. At the same time, using immuno-FISH with probes for chromosomes 14 and 15 in HeLa cells, we found that the cell pairs with identical combinations appeared significantly more frequently than predicted by the random model. Thus, although the total number of chromosomes associated with nucleoli is variable, our data indicate that the position of the NOR-bearing chromosomes in relation to nucleoli is partly conserved through mitosis.

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.

Mad2 binding to Mad1 and Cdc20, rather than oligomerization, is required for the spindle checkpoint

DEFF Research Database (Denmark)

Sironi, L; Melixetian, M; Faretta, M

2001-01-01

Mad2 is a key component of the spindle checkpoint, a device that controls the fidelity of chromosome segregation in mitosis. The ability of Mad2 to form oligomers in vitro has been correlated with its ability to block the cell cycle upon injection into Xenopus embryos. Here we show that Mad2 forms...

Solving block linear systems with low-rank off-diagonal blocks is easily parallelizable

Energy Technology Data Exchange (ETDEWEB)

Menkov, V. [Indiana Univ., Bloomington, IN (United States)

1996-12-31

An easily and efficiently parallelizable direct method is given for solving a block linear system Bx = y, where B = D + Q is the sum of a non-singular block diagonal matrix D and a matrix Q with low-rank blocks. This implicitly defines a new preconditioning method with an operation count close to the cost of calculating a matrix-vector product Qw for some w, plus at most twice the cost of calculating Qw for some w. When implemented on a parallel machine the processor utilization can be as good as that of those operations. Order estimates are given for the general case, and an implementation is compared to block SSOR preconditioning.

Rolling block mazes are PSPACE-complete

NARCIS (Netherlands)

Buchin, K.; Buchin, M.

2012-01-01

In a rolling block maze, one or more blocks lie on a rectangular board with square cells. In most mazes, the blocks have size k × m × n where k, m, n are integers that determine the size of the block in terms of units of the size of the board cells. The task of a rolling block maze is to roll a

A PMT-Block test bench

International Nuclear Information System (INIS)

Adragna, P.; Antonaki, A.

2006-01-01

The front-end electronics of the ATLAS hadronic calorimeter (Tile Cal) is housed in a unit, called PMT-Block. The PMT-Block is a compact instrument comprising a light mixer, a PMT together with its divider and a 3-in-1 card, which provides shaping, amplification and integration for the signals. This instrument needs to be qualified before being assembled on the detector. A PMT-Block test bench has been developed for this purpose. This test bench is a system which allows fast, albeit accurate enough, measurements of the main properties of a complete PMT-Block. The system, both hardware and software, and the protocol used for the PMT-Blocks characterization are described in detail in this report. The results obtained in the test of about 10 000 PMT-Blocks needed for the instrumentation of the ATLAS (LHC-CERN) hadronic Tile Calorimeter are also reported

A PMT-Block test bench

Energy Technology Data Exchange (ETDEWEB)

Adragna, P [Dipartimento di Fisica ' E.Fermi' , Universita di Pisa and Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, Largo B. Pontecorvo 3, Pisa 56127 (Italy); Universita degli studi di Siena, via Roma 56, 53100 Siena (Italy); Antonaki, A [Institute of Accelerating Systems and Applications, P.O. Box 17214, Athens 10024 (Greece); National Capodistrian University of Athens, 30 Panepistimiou st., Athens 10679 (Greece)] (and others)

2006-08-01

The front-end electronics of the ATLAS hadronic calorimeter (Tile Cal) is housed in a unit, called PMT-Block. The PMT-Block is a compact instrument comprising a light mixer, a PMT together with its divider and a 3-in-1 card, which provides shaping, amplification and integration for the signals. This instrument needs to be qualified before being assembled on the detector. A PMT-Block test bench has been developed for this purpose. This test bench is a system which allows fast, albeit accurate enough, measurements of the main properties of a complete PMT-Block. The system, both hardware and software, and the protocol used for the PMT-Blocks characterization are described in detail in this report. The results obtained in the test of about 10 000 PMT-Blocks needed for the instrumentation of the ATLAS (LHC-CERN) hadronic Tile Calorimeter are also reported.

Masquerading bundle branch block as a presenting manifestation of complete atrioventricular block that caused syncope.

Science.gov (United States)

Jiao, Zhenyu; Tian, Ying; Yang, Xinchun; Liu, Xingpeng

2017-10-01

A 59-year-old male patient was admitted with the main complaints of stuffiness and shortness of breath. An ECG from precordial leads on admission showed masquerading bundle branch block. Syncope frequently occurred after admission. During syncope episodes, ECG telemetry showed that the syncope was caused by intermittent complete atrioventricular block, with the longest RR interval lasting for 4.36 s. At the gap of syncope, ECG showed complete right bundle branch block accompanied by alternation of left anterior fascicular block and left posterior fascicular block. The patient was implanted with a dual-chamber permanent pacemaker. Follow-up of 9 months showed no reoccurrence of syncope.

Backfilling of deposition tunnels, block alternative

International Nuclear Information System (INIS)

Keto, P.; Roennqvist, P.-E.

2007-03-01

This report presents a preliminary process description of backfilling the deposition tunnels with pre-compacted blocks consisting of a mixture of bentonite and ballast (30:70). The process was modified for the Finnish KBS-3V type repository assuming that the amount of spent fuel canisters disposed of yearly is 40. Backfilling blocks (400 x 300 x 300 mm) are prepared in a block production plant with a hydraulic press with an estimated production capacity of 840 blocks per day. Some of the blocks are modified further to fit the profile of the tunnel roof. Prior to the installation of the blocks, the deposition tunnel floor is levelled with a mixture of bentonite and ballast (15:85). The blocks are placed in the tunnel with a modified reach truck. Centrifugal pellet throwing equipment is used to fill the gap between the blocks and the rock surface with bentonite pellets. Based on a preliminary assessment, the average dry density achieved with block backfill is sufficient to fulfil the criteria set for the backfill in order to ensure long-term safety and radiation protection. However, there are uncertainties concerning saturation, homogenisation, erosion, piping and self-healing of the block backfill that need to be studied further with laboratory and field tests. In addition, development efforts and testing concerning block manufacturing and installation are required to verify the technical feasibility of the concept. (orig.)

Emplacement of small and large buffer blocks

International Nuclear Information System (INIS)

Saari, H.; Nikula, M.; Suikki, M.

2010-05-01

The report describes emplacement of a buffer structure encircling a spent fuel canister to be deposited in a vertical hole. The report deals with installability of various size blocks and with an emplacement gear, as well as evaluates the achieved quality of emplacement and the time needed for installing the buffer. Two block assembly of unequal size were chosen for examination. A first option involved small blocks, the use of which resulted in a buffer structure consisting of small sector blocks 200 mm in height. A second option involved large blocks, resulting in a buffer structure which consists of eight blocks. In these tests, the material chosen for both block options was concrete instead of bentonite. The emplacement test was a three-phase process. A first phase included stacking a two meter high buffer structure with small blocks for ensuring the operation of test equipment and blocks. A second phase included installing buffer structures with both block options to a height matching that of a canister-encircling cylindrical component. A third phase included testing also the installability of blocks to be placed above the canister by using small blocks. In emplacement tests, special attention was paid to the installability of blocks as well as to the time required for emplacement. Lifters for both blocks worked well. Due to the mass to be lifted, the lifter for large blocks had a more heavy-duty frame structure (and other lifting gear). The employed lifters were suspended in the tests on a single steel wire rope. Stacking was managed with both block sizes at adequate precision and stacked-up towers were steady. The stacking of large blocks was considerably faster. Therefore it is probably that the overall handling of the large blocks will be more convenient at a final disposal site. From the standpoint of reliability in lifting, the small blocks were safer to install above the canister. In large blocks, there are strict shape-related requirements which are

Comparative study between ultrasound guided tap block and paravertebral block in upper abdominal surgeries. Randomized controlled trial

Directory of Open Access Journals (Sweden)

Ruqaya M. Elsayed

2017-01-01

Conclusion: We concluded that ultrasound guided transversus abdominis plane block and thoracic paravertebral block were safe and effective anesthetic technique for upper abdominal surgery with longer and potent postoperative analgesia in thoracic paravertebral block than transversus abdominis block.

Ionization of amphiphilic acidic block copolymers.

Science.gov (United States)

Colombani, Olivier; Lejeune, Elise; Charbonneau, Céline; Chassenieux, Christophe; Nicolai, Taco

2012-06-28

The ionization behavior of an amphiphilic diblock copolymer poly(n-butyl acrylate(50%)-stat-acrylic acid(50%))(100)-block-poly(acrylic acid)(100) (P(nBA(50%)-stat-AA(50%))(100)-b-PAA(100), DH50) and of its equivalent triblock copolymer P(nBA(50%)-stat-AA(50%))(100)-b-PAA(200)-b-P(nBA(50%)-stat-AA(50%))(100) (TH50) were studied by potentiometric titration either in pure water or in 0.5 M NaCl. These polymers consist of a hydrophilic acidic block (PAA) connected to a hydrophobic block, P(nBA(50%)-stat-AA(50%))(100), whose hydrophobic character has been mitigated by copolymerization with hydrophilic units. We show that all AA units, even those in the hydrophobic block could be ionized. However, the AA units within the hydrophobic block were less acidic than those in the hydrophilic block, resulting in the preferential ionization of the latter block. The preferential ionization of PAA over that of P(nBA(50%)-stat-AA(50%))(100) was stronger at higher ionic strength. Remarkably, the covalent bonds between the PAA and P(nBA(50%)-stat-AA(50%))(100) blocks in the diblock or the triblock did not affect the ionization of each block, although the self-association of the block copolymers into spherical aggregates modified the environment of the PAA blocks compared to when PAA was molecularly dispersed.

Integral-fuel blocks

International Nuclear Information System (INIS)

Cunningham, C.; Simpkin, S.D.

1975-01-01

A prismatic moderator block is described which has fuel-containing channels and coolant channels disposed parallel to each other and to edge faces of the block. The coolant channels are arranged in rows on an equilateral triangular lattice pattern and the fuel-containing channels are disposed in a regular lattice pattern with one fuel-containing channel between and equidistant from each of the coolant channels in each group of three mutually adjacent coolant channels. The edge faces of the block are parallel to the rows of coolant channels and the channels nearest to each edge face are disposed in two rows parallel thereto, with one of the rows containing only coolant channels and the other row containing only fuel-containing channels. (Official Gazette)

Comparison of the Effect of Continuous Femoral Nerve Block and Adductor Canal Block after Primary Total Knee Arthroplasty.

Science.gov (United States)

Seo, Seung Suk; Kim, Ok Gul; Seo, Jin Hyeok; Kim, Do Hoon; Kim, Youn Gu; Park, Beyoung Yun

2017-09-01

This study aimed to compare the effects of femoral nerve block and adductor canal block on postoperative pain, quadriceps strength, and walking ability after primary total knee arthroplasty. Between November 2014 and February 2015, 60 patients underwent primary total knee arthroplasty. Thirty patients received femoral nerve block and the other 30 received adductor canal block for postoperative pain control. Before spinal anesthesia, the patients received nerve block via a catheter (20 mL 0.75% ropivacaine was administered initially, followed by intermittent bolus injection of 10 mL 0.2% ropivacaine every 6 hours for 3 days). The catheters were maintained in the exact location of nerve block in 24 patients in the femoral nerve block group and in 19 patients in the adductor canal block group. Data collection was carried out from these 43 patients. To evaluate postoperative pain control, the numerical rating scale scores at rest and 45° flexion of the knee were recorded. To evaluate quadriceps strength, manual muscle testing was performed. Walking ability was assessed using the Timed Up and Go test. We also evaluated analgesic consumption and complications of peripheral nerve block. No significant intergroup difference was observed in the numerical rating scale scores at rest and 45° flexion of the knee on postoperative days 1, 2, 3, and 7. The adductor canal block group had significantly greater quadriceps strength than did the femoral nerve block group, as assessed by manual muscle testing on postoperative days 1, 2, and 3. The 2 groups showed no difference in walking ability on postoperative day 1, but on postoperative days 2, 3, walking ability was significantly better in the adductor canal block group than in the femoral nerve block group. No significant intergroup difference was observed in analgesic consumption. The groups showed no difference in postoperative pain control. Adductor canal block was superior to femoral nerve block in preserving quadriceps

Powered Explicit Guidance Modifications and Enhancements for Space Launch System Block-1 and Block-1B Vehicles

Science.gov (United States)

Von der Porten, Paul; Ahmad, Naeem; Hawkins, Matt; Fill, Thomas

2018-01-01

NASA is currently building the Space Launch System (SLS) Block-1 launch vehicle for the Exploration Mission 1 (EM-1) test flight. NASA is also currently designing the next evolution of SLS, the Block-1B. The Block-1 and Block-1B vehicles will use the Powered Explicit Guidance (PEG) algorithm (of Space Shuttle heritage) for closed loop guidance. To accommodate vehicle capabilities and design for future evolutions of SLS, modifications were made to PEG for Block-1 to handle multi-phase burns, provide PEG updated propulsion information, and react to a core stage engine out. In addition, due to the relatively low thrust-to-weight ratio of the Exploration Upper Stage (EUS) and EUS carrying out Lunar Vicinity and Earth Escape missions, certain enhancements to the Block-1 PEG algorithm are needed to perform Block-1B missions to account for long burn arcs and target translunar and hyperbolic orbits. This paper describes the design and implementation of modifications to the Block-1 PEG algorithm as compared to Space Shuttle. Furthermore, this paper illustrates challenges posed by the Block-1B vehicle and the required PEG enhancements. These improvements make PEG capable for use on the SLS Block-1B vehicle as part of the Guidance, Navigation, and Control (GN&C) System.

Building Curriculum during Block Play

Science.gov (United States)

Andrews, Nicole

2015-01-01

Blocks are not just for play! In this article, Nicole Andrews describes observing the interactions of three young boys enthusiastically engaged in the kindergarten block center of their classroom, using blocks in a building project that displayed their ability to use critical thinking skills, physics exploration, and the development of language…

Region 9 Census Block 2010

Science.gov (United States)

Geography:The TIGER Line Files are feature classes and related database files (.) that are an extract of selected geographic and cartographic information from the U.S. Census Bureau's Master Address File / Topologically Integrated Geographic Encoding and Referencing (MAF/TIGER) Database (MTDB). The MTDB represents a seamless national file with no overlaps or gaps between parts, however, each TIGER Line File is designed to stand alone as an independent data set, or they can be combined to cover the entire nation. Census Blocks are statistical areas bounded on all sides by visible features, such as streets, roads, streams, and railroad tracks, and/or by non visible boundaries such as city, town, township, and county limits, and short line-of-sight extensions of streets and roads. Census blocks are relatively small in area; for example, a block in a city bounded by streets. However, census blocks in remote areas are often large and irregular and may even be many square miles in area. A common misunderstanding is that data users think census blocks are used geographically to build all other census geographic areas, rather all other census geographic areas are updated and then used as the primary constraints, along with roads and water features, to delineate the tabulation blocks. As a result, all 2010 Census blocks nest within every other 2010 Census geographic area, so that Census Bureau statistical data can be tabulated at the block level and aggregated up t

Various semiclassical limits of torus conformal blocks

Energy Technology Data Exchange (ETDEWEB)

Alkalaev, Konstantin [I.E. Tamm Department of Theoretical Physics, P.N. Lebedev Physical Institute,Leninsky ave. 53, Moscow, 119991 (Russian Federation); Department of General and Applied Physics, Moscow Institute of Physics and Technology,Institutskiy per. 7, Dolgoprudnyi, Moscow region, 141700 (Russian Federation); Geiko, Roman [Mathematics Department, National Research University Higher School of Economics,Usacheva str. 6, Moscow, 119048 (Russian Federation); Rappoport, Vladimir [I.E. Tamm Department of Theoretical Physics, P.N. Lebedev Physical Institute,Leninsky ave. 53, Moscow, 119991 (Russian Federation); Department of Quantum Physics, Institute for Information Transmission Problems,Bolshoy Karetny per. 19, Moscow, 127994 (Russian Federation)

2017-04-12

We study four types of one-point torus blocks arising in the large central charge regime. There are the global block, the light block, the heavy-light block, and the linearized classical block, according to different regimes of conformal dimensions. It is shown that the blocks are not independent being connected to each other by various links. We find that the global, light, and heavy-light blocks correspond to three different contractions of the Virasoro algebra. Also, we formulate the c-recursive representation of the one-point torus blocks which is relevant in the semiclassical approximation.

Common blocks for ASQS(12

Directory of Open Access Journals (Sweden)

Lorenzo Milazzo

1997-05-01

Full Text Available An ASQS(v is a particular Steiner system featuring a set of v vertices and two separate families of blocks, B and G, whose elements have a respective cardinality of 4 and 6. It has the property that any three vertices of X belong either to a B-block or to a G-block. The parameter cb is the number of common blocks in two separate ASQSs, both defined on the same set of vertices X . In this paper it is shown that cb ≤ 29 for any pair of ASQSs(12.

Pectoral nerve block (Pecs block) with sedation for breast conserving surgery without general anesthesia.

Science.gov (United States)

Moon, Eun-Jin; Kim, Seung-Beom; Chung, Jun-Young; Song, Jeong-Yoon; Yi, Jae-Woo

2017-09-01

Most regional anesthesia in breast surgeries is performed as postoperative pain management under general anesthesia, and not as the primary anesthesia. Regional anesthesia has very few cardiovascular or pulmonary side-effects, as compared with general anesthesia. Pectoral nerve block is a relatively new technique, with fewer complications than other regional anesthesia. We performed Pecs I and Pec II block simultaneously as primary anesthesia under moderate sedation with dexmedetomidine for breast conserving surgery in a 49-year-old female patient with invasive ductal carcinoma. Block was uneventful and showed no complications. Thus, Pecs block with sedation could be an alternative to general anesthesia for breast surgeries.

49 CFR 236.708 - Block.

Science.gov (United States)

2010-10-01

... 49 Transportation 4 2010-10-01 2010-10-01 false Block. 236.708 Section 236.708 Transportation... OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES Definitions § 236.708 Block. A length of track of defined limits, the use of which by trains is governed by block signals, cab signals, or both. ...

Ultrasound-Guided Single-Injection Infraclavicular Block Versus Ultrasound-Guided Double-Injection Axillary Block: A Noninferiority Randomized Controlled Trial.

Science.gov (United States)

Boivin, Ariane; Nadeau, Marie-Josée; Dion, Nicolas; Lévesque, Simon; Nicole, Pierre C; Turgeon, Alexis F

2016-01-01

Single-injection ultrasound-guided infraclavicular block is a simple, reliable, and effective technique. A simplified double-injection ultrasound-guided axillary block technique with a high success rate recently has been described. It has the advantage of being performed in a superficial and compressible location, with a potentially improved safety profile. However, its effectiveness in comparison with single-injection infraclavicular block has not been established. We hypothesized that the double-injection ultrasound-guided axillary block would show rates of complete sensory block at 30 minutes noninferior to the single-injection ultrasound-guided infraclavicular block. After approval by our research ethics committee and written informed consent, adults undergoing distal upper arm surgery were randomized to either group I, ultrasound-guided single-injection infraclavicular block, or group A, ultrasound-guided double-injection axillary block. In group I, 30 mL of 1.5% mepivacaine was injected posterior to the axillary artery. In group A, 25 mL of 1.5% mepivacaine was injected posteromedial to the axillary artery, after which 5 mL was injected around the musculocutaneous nerve. Primary outcome was the rate of complete sensory block at 30 minutes. Secondary outcomes were the onset of sensory and motor blocks, surgical success rates, performance times, and incidence of complications. All outcomes were assessed by a blinded investigator. The noninferiority of the double-injection ultrasound-guided axillary block was considered if the limits of the 90% confidence intervals (CIs) were within a 10% margin of the rate of complete sensory block of the infraclavicular block. At 30 minutes, the rate of complete sensory block was 79% in group A (90% CI, 71%-85%) compared with 91% in group I (90% CI, 85%-95%); the upper limit of CI of group A is thus included in the established noninferiority margin of 10%. The rate of complete sensory block was lower in group A (proportion

Block copolymer battery separator

Science.gov (United States)

Wong, David; Balsara, Nitash Pervez

2016-04-26

The invention herein described is the use of a block copolymer/homopolymer blend for creating nanoporous materials for transport applications. Specifically, this is demonstrated by using the block copolymer poly(styrene-block-ethylene-block-styrene) (SES) and blending it with homopolymer polystyrene (PS). After blending the polymers, a film is cast, and the film is submerged in tetrahydrofuran, which removes the PS. This creates a nanoporous polymer film, whereby the holes are lined with PS. Control of morphology of the system is achieved by manipulating the amount of PS added and the relative size of the PS added. The porous nature of these films was demonstrated by measuring the ionic conductivity in a traditional battery electrolyte, 1M LiPF.sub.6 in EC/DEC (1:1 v/v) using AC impedance spectroscopy and comparing these results to commercially available battery separators.

Atrial Fibrillation, Atrioventricular Blocks and Bundle Branch Blocks in Hemodialysis Patients

OpenAIRE

Mandic, Ante; Tomic, Monika; Petrov, Bozo; Romic, Zeljko

2012-01-01

Atrial fibrillation is one of the most frequent arrhythmias diagnosed in clinical practice and it is also relatively common in dialysis patients. Atrioventricular and intraventricular conduction disturbances are less investigated in hemodialysis patients and data about their prevalence are insufficient. The objective of this study was to determine the prevalence of atrial fibrillation, atrioventricular blocks and bundle branch blocks in hemodialysis patients and to analyze different clinical ...

Strength and deformability of hollow concrete blocks: correlation of block and cylindrical sample test results

Directory of Open Access Journals (Sweden)

C. S. Barbosa

Full Text Available This paper deals with correlations among mechanical properties of hollow blocks and those of concrete used to make them. Concrete hollow blocks and test samples were moulded with plastic consistency concrete, to assure the same material in all cases, in three diferente levels of strength (nominally 10 N/mm², 20 N/mm² and 30 N/mm². The mechanical properties and structural behaviour in axial compression and tension tests were determined by standard tests in blocks and cylinders. Stress and strain analyses were made based on concrete’s modulus of elasticity obtained in the sample tests as well as on measured strain in the blocks’ face-shells and webs. A peculiar stress-strain analysis, based on the superposition of effects, provided an estimation of the block load capacity based on its deformations. In addition, a tentative method to preview the block deformability from the concrete mechanical properties is described and tested. This analysis is a part of a broader research that aims to support a detailed structural analysis of blocks, prisms and masonry constructions.

Reversible chronic acquired complete atrioventricular block.

Science.gov (United States)

Rakovec, P; Milcinski, G; Voga, G; Korsic, L

1982-01-01

The return of atrioventricular conduction is reported in a case after nearly four years of complete acquired heart block. After recovery from atrioventricular block, right bundle branch block persisted, but P-R interval and H-V interval were normal. Three months later a relapse of second degree infranodal atrioventricular block was noted. A short review of similar cases from the literature is given.

Compaction of bentonite blocks. Development of techniques for production of blocks with different shapes and sizes

International Nuclear Information System (INIS)

Johannesson, Lars-Erik; Boergesson, Lennart

1998-09-01

In this report useful techniques for producing both smaller blocks manageable by man (10-15 kg) and larger blocks which need special equipment for handling (weight up to 600 kg) are described. Tests for producing blocks with a weight of approximately 10 kg were carried out at Hoeganaes Bjuf AB in Bjuv. This industry is normally producing refractory bricks and other refractory products. The plant has facilities for handling large volumes of clay. It also has machines suitable for producing uniaxially compacted blocks. Tests performed at the plant show that it is possible to compact blocks with good quality. The best quality was reached with a coarsely ground bentonite at a water ratio of 17 %. The compaction rate was high and performed with lubricated form and stepwise loading. Tests, in order to find a technique for producing larger blocks with a diameter of the same size as a deposition hole (about 1.65 m), were also made. The technique was developed in a smaller scale (250 mm). Ring-shaped blocks with the same outer diameter and with an inner diameter of about 156 mm were also compacted. The compaction was made with vacuum in the form. The outer surface of the form was conical and most of the tests were performed with a lubricated form. Tests were performed with different water ratios of the bentonite. All the blocks had a good quality. In consequence of the good test results a form with a 1000 mm diameter was constructed and a number of compaction tests were performed. The same technique was used as for the smaller blocks. The compaction pressure in most tests was 100 MPa (maximum compaction load 80.000 kN). The tests were performed at HYDROWELD in Ystad in a press with a maximum capacity of 300.000 kN. All tests were performed with MX-80. Most of the blocks had a good quality. A small damage close to the upper surface of all blocks was observed but is considered to be of no importance for the possibility to handle the blocks and is not affecting the properties

Compaction of bentonite blocks. Development of techniques for production of blocks with different shapes and sizes

Energy Technology Data Exchange (ETDEWEB)

Johannesson, Lars-Erik; Boergesson, Lennart [Clay Technology AB, Lund (Sweden)

1998-09-01

In this report useful techniques for producing both smaller blocks manageable by man (10-15 kg) and larger blocks which need special equipment for handling (weight up to 600 kg) are described. Tests for producing blocks with a weight of approximately 10 kg were carried out at Hoeganaes Bjuf AB in Bjuv. This industry is normally producing refractory bricks and other refractory products. The plant has facilities for handling large volumes of clay. It also has machines suitable for producing uniaxially compacted blocks. Tests performed at the plant show that it is possible to compact blocks with good quality. The best quality was reached with a coarsely ground bentonite at a water ratio of 17 %. The compaction rate was high and performed with lubricated form and stepwise loading. Tests, in order to find a technique for producing larger blocks with a diameter of the same size as a deposition hole (about 1.65 m), were also made. The technique was developed in a smaller scale (250 mm). Ring-shaped blocks with the same outer diameter and with an inner diameter of about 156 mm were also compacted. The compaction was made with vacuum in the form. The outer surface of the form was conical and most of the tests were performed with a lubricated form. Tests were performed with different water ratios of the bentonite. All the blocks had a good quality. In consequence of the good test results a form with a 1000 mm diameter was constructed and a number of compaction tests were performed. The same technique was used as for the smaller blocks. The compaction pressure in most tests was 100 MPa (maximum compaction load 80.000 kN). The tests were performed at HYDROWELD in Ystad in a press with a maximum capacity of 300.000 kN. All tests were performed with MX-80. Most of the blocks had a good quality. A small damage close to the upper surface of all blocks was observed but is considered to be of no importance for the possibility to handle the blocks and is not affecting the properties

Bullet-Block Science Video Puzzle

Science.gov (United States)

Shakur, Asif

2015-01-01

A science video blog, which has gone viral, shows a wooden block shot by a vertically aimed rifle. The video shows that the block hit dead center goes exactly as high as the one shot off-center. (Fig. 1). The puzzle is that the block shot off-center carries rotational kinetic energy in addition to the gravitational potential energy. This leads a…

Cellient™ automated cell block versus traditional cell block preparation: a comparison of morphologic features and immunohistochemical staining.

Science.gov (United States)

Wagner, David G; Russell, Donna K; Benson, Jenna M; Schneider, Ashley E; Hoda, Rana S; Bonfiglio, Thomas A

2011-10-01

Traditional cell block (TCB) sections serve as an important diagnostic adjunct to cytologic smears but are also used today as a reliable preparation for immunohistochemical (IHC) studies. There are many ways to prepare a cell block and the methods continue to be revised. In this study, we compare the TCB with the Cellient™ automated cell block system. Thirty-five cell blocks were obtained from 16 benign and 19 malignant nongynecologic cytology specimens at a large university teaching hospital and prepared according to TCB and Cellient protocols. Cell block sections from both methods were compared for possible differences in various morphologic features and immunohistochemical staining patterns. In the 16 benign cases, no significant morphologic differences were found between the TCB and Cellient cell block sections. For the 19 malignant cases, some noticeable differences in the nuclear chromatin and cellularity were identified, although statistical significance was not attained. Immunohistochemical or special stains were performed on 89% of the malignant cases (17/19). Inadequate cellularity precluded full evaluation in 23% of Cellient cell block IHC preparations (4/17). Of the malignant cases with adequate cellularity (13/17), the immunohistochemical staining patterns from the different methods were identical in 53% of cases. The traditional and Cellient cell block sections showed similar morphologic and immunohistochemical staining patterns. The only significant difference between the two methods concerned the lower overall cell block cellularity identified during immunohistochemical staining in the Cellient cell block sections. Copyright © 2010 Wiley-Liss, Inc.

Compatibilization of low-density polyethylene/polystyrene blends by segmented EB(PS-block-EB)(n) block copolymers

NARCIS (Netherlands)

Kroeze, E; ten Brinke, G.; Hadziioannou, G

Hydrogenated segmented poly[butadiene-block-(styrene-block-butadiene)(n)] block copolymers, which were developed by use of a polymeric iniferter technique, were tested on their compatibilizing effectiveness for (10/90) LDPE/PS blends. They were found to be effective compatibilizers for this mixture,

Light extraction block with curved surface

Science.gov (United States)

Levermore, Peter; Krall, Emory; Silvernail, Jeffrey; Rajan, Kamala; Brown, Julia J.

2016-03-22

Light extraction blocks, and OLED lighting panels using light extraction blocks, are described, in which the light extraction blocks include various curved shapes that provide improved light extraction properties compared to parallel emissive surface, and a thinner form factor and better light extraction than a hemisphere. Lighting systems described herein may include a light source with an OLED panel. A light extraction block with a three-dimensional light emitting surface may be optically coupled to the light source. The three-dimensional light emitting surface of the block may includes a substantially curved surface, with further characteristics related to the curvature of the surface at given points. A first radius of curvature corresponding to a maximum principal curvature k.sub.1 at a point p on the substantially curved surface may be greater than a maximum height of the light extraction block. A maximum height of the light extraction block may be less than 50% of a maximum width of the light extraction block. Surfaces with cross sections made up of line segments and inflection points may also be fit to approximated curves for calculating the radius of curvature.

2-Methyl-3-(2-methylphenyl-4-oxo-3,4-dihydroquinazolin-8-yl 4-bromobenzene-1-sulfonate

Directory of Open Access Journals (Sweden)

Edward R. T. Tiekink

2012-03-01

Full Text Available The title molecule, C22H17BrN2O4S, has a twisted U shape, the dihedral angle between the quinazolin-4-one and bromobenzene ring systems being 46.25 (8°. In order to avoid steric clashes with adjacent substituents on the quinazolin-4-one ring, the N-bound tolyl group occupies an orthogonal position [dihedral angle = 89.59 (8°]. In the crystal, molecules are connected into a three-dimensional architecture by C—H...O interactions, with the ketone O atom accepting two such bonds and a sulfonate O atom one.

Contributions of hard and soft blocks in the self-healing of metal-ligand-containing block copolymers

NARCIS (Netherlands)

Bose, Ranjita K.; Enke, Marcel; Grande, Antonio M.; Zechel, Stefan; Schacher, Felix H.; Hager, Martin D.; Garcia, Santiago J.; Schubert, Ulrich S.; van der Zwaag, Sybrand

2017-01-01

The main aim of this work is to study the respective contribution of the hard and soft blocks of a metal-ligand containing block copolymer to the self-healing behavior. To this aim, different block copolymers containing terpyridine were synthesized using reversible addition-fragmentation chain

Evolutionary conservation and network structure characterize genes of phenotypic relevance for mitosis in human.

Directory of Open Access Journals (Sweden)

Marek Ostaszewski

Full Text Available The impact of gene silencing on cellular phenotypes is difficult to establish due to the complexity of interactions in the associated biological processes and pathways. A recent genome-wide RNA knock-down study both identified and phenotypically characterized a set of important genes for the cell cycle in HeLa cells. Here, we combine a molecular interaction network analysis, based on physical and functional protein interactions, in conjunction with evolutionary information, to elucidate the common biological and topological properties of these key genes. Our results show that these genes tend to be conserved with their corresponding protein interactions across several species and are key constituents of the evolutionary conserved molecular interaction network. Moreover, a group of bistable network motifs is found to be conserved within this network, which are likely to influence the network stability and therefore the robustness of cellular functioning. They form a cluster, which displays functional homogeneity and is significantly enriched in genes phenotypically relevant for mitosis. Additional results reveal a relationship between specific cellular processes and the phenotypic outcomes induced by gene silencing. This study introduces new ideas regarding the relationship between genotype and phenotype in the context of the cell cycle. We show that the analysis of molecular interaction networks can result in the identification of genes relevant to cellular processes, which is a promising avenue for future research.

Sequential activities of Dynein, Mud and Asp in centrosome-spindle coupling maintain centrosome number upon mitosis.

Science.gov (United States)

Bosveld, Floris; Ainslie, Anna; Bellaïche, Yohanns

2017-10-15

Centrosomes nucleate microtubules and are tightly coupled to the bipolar spindle to ensure genome integrity, cell division orientation and centrosome segregation. While the mechanisms of centrosome-dependent microtubule nucleation and bipolar spindle assembly have been the focus of numerous works, less is known about the mechanisms ensuring the centrosome-spindle coupling. The conserved NuMA protein (Mud in Drosophila ) is best known for its role in spindle orientation. Here, we analyzed the role of Mud and two of its interactors, Asp and Dynein, in the regulation of centrosome numbers in Drosophila epithelial cells. We found that Dynein and Mud mainly initiate centrosome-spindle coupling prior to nuclear envelope breakdown (NEB) by promoting correct centrosome positioning or separation, while Asp acts largely independently of Dynein and Mud to maintain centrosome-spindle coupling. Failure in the centrosome-spindle coupling leads to mis-segregation of the two centrosomes into one daughter cell, resulting in cells with supernumerary centrosomes during subsequent divisions. Altogether, we propose that Dynein, Mud and Asp operate sequentially during the cell cycle to ensure efficient centrosome-spindle coupling in mitosis, thereby preventing centrosome mis-segregation to maintain centrosome number. © 2017. Published by The Company of Biologists Ltd.

Contributions of hard and soft blocks in the self-healing of metal-ligand-containing block copolymers

NARCIS (Netherlands)

Bose, R.K.; Enke, Marcel; Grande, A.M.; Zechel, Stefan; Schacher, Felix H.; Hager, Martin D.; Garcia Espallargas, Santiago J.; Schubert, Ulrich S.; van der Zwaag, S.

2017-01-01

The main aim of this work is to study the respective contribution of the hard and soft blocks of a metal-ligand containing block copolymer to the self-healing behavior. To this aim, different block copolymers containing terpyridine were synthesized using reversible addition-fragmentation chain

Blending of styrene-block-butadiene-block-styrene copolymer with sulfonated vinyl aromatic polymers

NARCIS (Netherlands)

Ruggeri, Giacomo; Passaglia, Elisa; Giorgi, Ivan; Picchioni, Francesco; Aglietto, Mauro

2001-01-01

Different polymers containing sulfonic groups attached to the phenyl rings were prepared by sulfonation of polystyrene (PS) and styrene-block-(ethylene-co-1-butene)-block-styrene (SEBS). The sulfonation degree (SD) was varied between 1 and 20 mol% of the styrene units. Polyphase materials containing

Comparison of the Cellient(™) automated cell block system and agar cell block method.

Science.gov (United States)

Kruger, A M; Stevens, M W; Kerley, K J; Carter, C D

2014-12-01

To compare the Cellient(TM) automated cell block system with the agar cell block method in terms of quantity and quality of diagnostic material and morphological, histochemical and immunocytochemical features. Cell blocks were prepared from 100 effusion samples using the agar method and Cellient system, and routinely sectioned and stained for haematoxylin and eosin and periodic acid-Schiff with diastase (PASD). A preliminary immunocytochemical study was performed on selected cases (27/100 cases). Sections were evaluated using a three-point grading system to compare a set of morphological parameters. Statistical analysis was performed using Fisher's exact test. Parameters assessing cellularity, presence of single cells and definition of nuclear membrane, nucleoli, chromatin and cytoplasm showed a statistically significant improvement on Cellient cell blocks compared with agar cell blocks (P cell groups, PASD staining or the intensity or clarity of immunocytochemical staining. A discrepant immunocytochemistry (ICC) result was seen in 21% (13/63) of immunostains. The Cellient technique is comparable with the agar method, with statistically significant results achieved for important morphological features. It demonstrates potential as an alternative cell block preparation method which is relevant for the rapid processing of fine needle aspiration samples, malignant effusions and low-cellularity specimens, where optimal cell morphology and architecture are essential. Further investigation is required to optimize immunocytochemical staining using the Cellient method. © 2014 John Wiley & Sons Ltd.

Two injection digital block versus single subcutaneous palmar injection block for finger lacerations.

Science.gov (United States)

Okur, O M; Şener, A; Kavakli, H Ş; Çelik, G K; Doğan, N Ö; Içme, F; Günaydin, G P

2017-12-01

We aimed to compare two digital nerve block techniques in patients due to traumatic digital lacerations. This was a randomized-controlled study designed prospectively in the emergency department of a university-based training and research hospital. Randomization was achieved by sealed envelopes. Half of the patients were randomised to traditional (two-injection) digital nerve block technique while single-injection digital nerve block technique was applied to the other half. Score of pain due to anesthetic infiltration and suturing, onset time of total anesthesia, need for an additional rescue injection were the parameters evaluated with both groups. Epinephrin added lidocaine hydrochloride preparation was used for the anesthetic application. Visual analog scale was used for the evaluation of pain scores. Outcomes were compared by using Mann-Whitney U test and Student t-test. Fifty emergency department patients ≥18 years requiring digital nerve block were enrolled in the study. Mean age of the patients was 33 (min-max: 19-86) and 39 (78 %) were male. No statistically significant difference was found between the two groups in terms of our main parameters; anesthesia pain score, suturing pain score, onset time of total anesthesia and rescue injection need. Single injection volar digital nerve block technique is a suitable alternative for digital anesthesias in emergency departments.

Related Drupal Nodes Block

NARCIS (Netherlands)

Van der Vegt, Wim

2010-01-01

Related Drupal Nodes Block This module exposes a block that uses Latent Semantic Analysis (Lsa) internally to suggest three nodes that are relevant to the node a user is viewing. This module performs three tasks. 1) It periodically indexes a Drupal site and generates a Lsa Term Document Matrix.

Application of multi-block methods in cement production

DEFF Research Database (Denmark)

Svinning, K.; Høskuldsson, Agnar

2008-01-01

distribution and the two last blocks the superficial microstructure analysed by differential thermo gravimetric analysis. The multi-block method is used to identify the role of each part. The score vectors of each block can be analysed separately or together with score vectors of other blocks. Stepwise......Compressive strength at 1 day of Portland cement as a function of the microstructure of cement was statistically modelled by application of multi-block regression method. The observation X-matrix was partitioned into four blocks, the first block representing the mineralogy, the second particle size...... regression is used to find minimum number of variables of each block. The multi-block method proved useful in determining the modelling strength of each data block and finding minimum number of variables within each data block....

Right bundle branch block

DEFF Research Database (Denmark)

Bussink, Barbara E; Holst, Anders Gaarsdal; Jespersen, Lasse

2013-01-01

AimsTo determine the prevalence, predictors of newly acquired, and the prognostic value of right bundle branch block (RBBB) and incomplete RBBB (IRBBB) on a resting 12-lead electrocardiogram in men and women from the general population.Methods and resultsWe followed 18 441 participants included...... in the Copenhagen City Heart Study examined in 1976-2003 free from previous myocardial infarction (MI), chronic heart failure, and left bundle branch block through registry linkage until 2009 for all-cause mortality and cardiovascular outcomes. The prevalence of RBBB/IRBBB was higher in men (1.4%/4.7% in men vs. 0.......5%/2.3% in women, P block was associated with significantly...

Isostatic compression of buffer blocks. Middle scale

International Nuclear Information System (INIS)

Ritola, J.; Pyy, E.

2012-01-01

Manufacturing of buffer components using isostatic compression method has been studied in small scale in 2008 (Laaksonen 2010). These tests included manufacturing of buffer blocks using different bentonite materials and different compression pressures. Isostatic mould technology was also tested, along with different methods to fill the mould, such as vibration and partial vacuum, as well as a stepwise compression of the blocks. The development of manufacturing techniques has continued with small-scale (30 %) blocks (diameter 600 mm) in 2009. This was done in a separate project: Isostatic compression, manufacturing and testing of small scale (D = 600 mm) buffer blocks. The research on the isostatic compression method continued in 2010 in a project aimed to test and examine the isostatic manufacturing process of buffer blocks at 70 % scale (block diameter 1200 to 1300 mm), and the aim was to continue in 2011 with full-scale blocks (diameter 1700 mm). A total of nine bentonite blocks were manufactured at 70 % scale, of which four were ring-shaped and the rest were cylindrical. It is currently not possible to manufacture full-scale blocks, because there is no sufficiently large isostatic press available. However, such a compression unit is expected to be possible to use in the near future. The test results of bentonite blocks, produced with an isostatic pressing method at different presses and at different sizes, suggest that the technical characteristics, for example bulk density and strength values, are somewhat independent of the size of the block, and that the blocks have fairly homogenous characteristics. Water content and compression pressure are the two most important properties determining the characteristics of the compressed blocks. By adjusting these two properties it is fairly easy to produce blocks at a desired density. The commonly used compression pressure in the manufacturing of bentonite blocks is 100 MPa, which compresses bentonite to approximately

Isostatic compression of buffer blocks. Middle scale

Energy Technology Data Exchange (ETDEWEB)

Ritola, J.; Pyy, E. [VTT Technical Research Centre of Finland, Espoo (Finland)

2012-01-15

Manufacturing of buffer components using isostatic compression method has been studied in small scale in 2008 (Laaksonen 2010). These tests included manufacturing of buffer blocks using different bentonite materials and different compression pressures. Isostatic mould technology was also tested, along with different methods to fill the mould, such as vibration and partial vacuum, as well as a stepwise compression of the blocks. The development of manufacturing techniques has continued with small-scale (30 %) blocks (diameter 600 mm) in 2009. This was done in a separate project: Isostatic compression, manufacturing and testing of small scale (D = 600 mm) buffer blocks. The research on the isostatic compression method continued in 2010 in a project aimed to test and examine the isostatic manufacturing process of buffer blocks at 70 % scale (block diameter 1200 to 1300 mm), and the aim was to continue in 2011 with full-scale blocks (diameter 1700 mm). A total of nine bentonite blocks were manufactured at 70 % scale, of which four were ring-shaped and the rest were cylindrical. It is currently not possible to manufacture full-scale blocks, because there is no sufficiently large isostatic press available. However, such a compression unit is expected to be possible to use in the near future. The test results of bentonite blocks, produced with an isostatic pressing method at different presses and at different sizes, suggest that the technical characteristics, for example bulk density and strength values, are somewhat independent of the size of the block, and that the blocks have fairly homogenous characteristics. Water content and compression pressure are the two most important properties determining the characteristics of the compressed blocks. By adjusting these two properties it is fairly easy to produce blocks at a desired density. The commonly used compression pressure in the manufacturing of bentonite blocks is 100 MPa, which compresses bentonite to approximately

Uniaxial backfill block compaction

International Nuclear Information System (INIS)

Koskinen, V.

2012-05-01

The main parts of the project were: to make a literature survey of the previous uniaxial compaction experiments; do uniaxial compaction tests in laboratory scale; and do industrial scale production tests. Object of the project was to sort out the different factors affecting the quality assurance chain of the backfill block uniaxial production and solve a material sticking to mould problem which appeared during manufacturing the blocks of bentonite and cruched rock mixture. The effect of mineralogical and chemical composition on the long term functionality of the backfill was excluded from the project. However, the used smectite-rich clays have been tested for mineralogical consistency. These tests were done in B and Tech OY according their SOPs. The objective of the Laboratory scale tests was to find right material- and compaction parameters for the industrial scale tests. Direct comparison between the laboratory scale tests and industrial scale tests is not possible because the mould geometry and compaction speed has a big influence for the compaction process. For this reason the selected material parameters were also affected by the previous compaction experiments. The industrial scale tests were done in summer of 2010 in southern Sweden. Blocks were done with uniaxial compaction. A 40 tons of the mixture of bentonite and crushed rock blocks and almost 50 tons of Friedland-clay blocks were compacted. (orig.)

Impression block with orientator

International Nuclear Information System (INIS)

Brilin, V I; Ulyanova, O S

2015-01-01

Tool review, namely the impression block, applied to check the shape and size of the top of fish as well as to determine the appropriate tool for fishing operation was realized. For multiple application and obtaining of the impress depth of 3 cm and more, the standard volumetric impression blocks with fix rods are used. However, the registered impress of fish is not oriented in space and the rods during fishing are in the extended position. This leads to rods deformation and sinking due to accidental impacts of impression block over the borehole irregularity and finally results in faulty detection of the top end of fishing object in hole. The impression blocks with copy rods and fixed magnetic needle allow estimating the object configuration and fix the position of magnetic needle determining the position of the top end of object in hole. However, the magnetic needle fixation is realized in staged and the rods are in extended position during fishing operations as well as it is in standard design. The most efficient tool is the impression block with copy rods which directs the examined object in the borehole during readings of magnetic needles data from azimuth plate and averaging of readings. This significantly increases the accuracy of fishing toll direction. The rods during fishing are located in the body and extended only when they reach the top of fishing object

Phrenic nerve block caused by interscalene brachial plexus block: breathing effects of different sites of injection.

Science.gov (United States)

Bergmann, Lars; Martini, Stefan; Kesselmeier, Miriam; Armbruster, Wolf; Notheisen, Thomas; Adamzik, Michael; Eichholz, Rϋdiger

2016-07-29

Interscalene brachial plexus (ISB) block is often associated with phrenic nerve block and diaphragmatic paresis. The goal of our study was to test if the anterior or the posterior ultrasound guided approach of the ISB is associated with a lower incidence of phrenic nerve blocks and impaired lung function. This was a prospective, randomized and single-blinded study of 84 patients scheduled for elective shoulder surgery who fullfilled the inclusion and exclusion critereria. Patients were randomized in two groups to receive either the anterior (n = 42) or the posterior (n = 42) approach for ISB. Clinical data were recorded. In both groups patients received ISB with a total injection volume of 15 ml of ropivacaine 1 %. Spirometry was conducted at baseline (T0) and 30 min (T30) after accomplishing the block. Changes in spirometrical variables between T0 and T30 were investigated by Wilcoxon signed-rank test for each puncture approach. The temporal difference between the posterior and the anterior puncture approach groups were again analyzed by the Wilcoxon-Mann-Whitney test. The spirometric results showed a significant decrease in vital capacity, forced expiratory volume per second, and maximum nasal inspiratory breathing after the Interscalene brachial plexus block; indicating a phrenic nerve block (p Wilcoxon signed-rank). A significant difference in the development of the spirometric parameters between the anterior and the posterior group could not be identified (Wilcoxon-Mann-Whitney test). Despite the changes in spirometry, no cases of dyspnea were reported. A different site of injection (anterior or posterior) did not show an effect in reducing the cervical block spread of the local anesthetic and the incidence of phrenic nerve blocks during during ultrasound guided Interscalene brachial plexus block. Clinical breathing effects of phrenic nerve blocks are, however, usually well compensated, and subjective dyspnea did not occur in our patients. German

49 CFR 236.804 - Signal, block.

Science.gov (United States)

2010-10-01

... 49 Transportation 4 2010-10-01 2010-10-01 false Signal, block. 236.804 Section 236.804 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Signal, block. A roadway signal operated either automatically or manually at the entrance to a block. ...

Toward Composable Hardware Agnostic Communications Blocks Lessons Learned

Science.gov (United States)

2016-11-01

block-by-block level or on a multi- block level. In the block-by-block pushback approach, queues between each block are small and blocks processing data...medium access, and physical layers of the waveform has limited our ability to take advantage of technology advances in signal processing , rate...pro- cessing functions, and application processing functions as shown in Figure 1 [1]. Transceiver functions are functions associated with transmitting

Micellar aggregates of amylose-block-polystyrene rod-coil block copolymers in water and THF

NARCIS (Netherlands)

Loos, Katja; Böker, Alexander; Zettl, Heiko; Zhang, Mingfu; Krausch, Georg; Müller, Axel H.E.; Boker, A.; Zhang, A.F.

2005-01-01

Amylose-block-polystyrenes with various block copolymer compositions were investigated in water and in THF solution. Fluorescence correlation spectroscopy, dynamic light, scattering (DLS), and asymmetric flow field-flow fractionation with multiangle light scattering detection indicate the presence

A comparison of oblique subcostal transversus abdominis plane block versus thoracic paravertebral block for postoperative analgesia after open cholecystectomy

Directory of Open Access Journals (Sweden)

Ghada Kamhawy

2017-10-01

Full Text Available Background: A major challenge in the postoperative period is pain management which, if not adequately controlled, may contribute to patient discomfort and decreased patient satisfaction, and possibly increased morbidity and mortality. Both Thoracic paravertebral block and oblique subcostal transversus abdominis plane block can be used as analgesic techniques for abdominal surgeries. Our aim in this research was comparison of cumulative 24-h post-operative morphine consumption between ultrasound-guided oblique subcostal transversus abdominis plane block and ultrasound-guided thoracic paravertebral block in patients who underwent an open cholecystectomy under general anesthesia. Patients and methods: This study was performed on 46 patients who underwent open cholecystectomy under general anesthesia. All patients were randomly allocated alternatively to one of two equal groups to either undergo ultrasound-guided unilateral oblique subcostal transversus abdominis plane block Group (I or to undergo ultrasound-guided unilateral thoracic paravertebral block Group (II. Both groups were subjected to a similar analgesic regimen in the immediate post-operative period that involved intravenous patient-controlled morphine analgesia which was used in both groups. Results: The total morphine consumption in the first postoperative 24 h was lower in thoracic paravertebral block Group (II (9.9 mg in thoracic paravertebral block group vs. 15.4 mg in oblique subcostal transversus abdominis plane block Group (I with p < 0.001. The mean time of first request of analgesia in Group (I was 248.7 min compared to 432.1 for Group (II with p < 0.001. Conclusions: Both ultrasound-guided oblique subcostal transversus abdominis plain block and single injection ultrasound guided thoracic paravertebral block are effective analgesic techniques for upper abdominal surgeries and reduces postoperative opioid requirements. However, thoracic paravertebral block is more

Habitat Blocks and Wildlife Corridors

Data.gov (United States)

Vermont Center for Geographic Information — Habitat blocks are areas of contiguous forest and other natural habitats that are unfragmented by roads, development, or agriculture. Vermonts habitat blocks are...

Recursion Relations for Conformal Blocks

CERN Document Server

Penedones, João; Yamazaki, Masahito

2016-09-12

In the context of conformal field theories in general space-time dimension, we find all the possible singularities of the conformal blocks as functions of the scaling dimension $\\Delta$ of the exchanged operator. In particular, we argue, using representation theory of parabolic Verma modules, that in odd spacetime dimension the singularities are only simple poles. We discuss how to use this information to write recursion relations that determine the conformal blocks. We first recover the recursion relation introduced in 1307.6856 for conformal blocks of external scalar operators. We then generalize this recursion relation for the conformal blocks associated to the four point function of three scalar and one vector operator. Finally we specialize to the case in which the vector operator is a conserved current.

Block-Parallel Data Analysis with DIY2

Energy Technology Data Exchange (ETDEWEB)

Morozov, Dmitriy [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Peterka, Tom [Argonne National Lab. (ANL), Argonne, IL (United States)

2017-08-30

DIY2 is a programming model and runtime for block-parallel analytics on distributed-memory machines. Its main abstraction is block-structured data parallelism: data are decomposed into blocks; blocks are assigned to processing elements (processes or threads); computation is described as iterations over these blocks, and communication between blocks is defined by reusable patterns. By expressing computation in this general form, the DIY2 runtime is free to optimize the movement of blocks between slow and fast memories (disk and flash vs. DRAM) and to concurrently execute blocks residing in memory with multiple threads. This enables the same program to execute in-core, out-of-core, serial, parallel, single-threaded, multithreaded, or combinations thereof. This paper describes the implementation of the main features of the DIY2 programming model and optimizations to improve performance. DIY2 is evaluated on benchmark test cases to establish baseline performance for several common patterns and on larger complete analysis codes running on large-scale HPC machines.

Assessment of exit block following pulmonary vein isolation: far-field capture masquerading as entrance without exit block.

Science.gov (United States)

Vijayaraman, Pugazhendhi; Dandamudi, Gopi; Naperkowski, Angela; Oren, Jess; Storm, Randle; Ellenbogen, Kenneth A

2012-10-01

Complete electrical isolation of pulmonary veins (PVs) remains the cornerstone of ablation therapy for atrial fibrillation. Entrance block without exit block has been reported to occur in 40% of the patients. Far-field capture (FFC) can occur during pacing from the superior PVs to assess exit block, and this may appear as persistent conduction from PV to left atrium (LA). To facilitate accurate assessment of exit block. Twenty consecutive patients with symptomatic atrial fibrillation referred for ablation were included in the study. Once PV isolation (entrance block) was confirmed, pacing from all the bipoles on the Lasso catheter was used to assess exit block by using a pacing stimulus of 10 mA at 2 ms. Evidence for PV capture without conduction to LA was necessary to prove exit block. If conduction to LA was noticed, pacing output was decreased until there was PV capture without conduction to LA or no PV capture was noted to assess for far-field capture in both the upper PVs. All 20 patients underwent successful isolation (entrance block) of all 76 (4 left common PV) veins: mean age 58 ± 9 years; paroxysmal atrial fibrillation 40%; hypertension 70%, diabetes mellitus 30%, coronary artery disease 15%; left ventricular ejection fraction 55% ± 10%; LA size 42 ± 11 mm. Despite entrance block, exit block was absent in only 16% of the PVs, suggesting persistent PV to LA conduction. FFC of LA appendage was noted in 38% of the left superior PVs. FFC of the superior vena cava was noted in 30% of the right superior PVs. The mean pacing threshold for FFC was 7 ± 4 mA. Decreasing pacing output until only PV capture (loss of FFC) is noted was essential to confirm true exit block. FFC of LA appendage or superior vena cava can masquerade as persistent PV to LA conduction. A careful assessment for PV capture at decreasing pacing output is essential to exclude FFC. Copyright © 2012 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Atrioventricular block, ECG tracing (image)

Science.gov (United States)

... an abnormal rhythm (arrhythmia) called an atrioventricular (AV) block. P waves show that the top of the ... wave (and heart contraction), there is an atrioventricular block, and a very slow pulse (bradycardia).

Quadratus Lumborum Block Versus Transversus Abdominis Plane Block for Postoperative Pain After Cesarean Delivery: A Randomized Controlled Trial.

Science.gov (United States)

Blanco, Rafael; Ansari, Tarek; Riad, Waleed; Shetty, Nanda

Effective postoperative analgesia after cesarean delivery enhances early recovery, ambulation, and breastfeeding. In a previous study, we established the effectiveness of the quadratus lumborum block in providing pain relief after cesarean delivery compared with patient-controlled analgesia (morphine). In the current study, we hypothesized that this method would be equal to or better than the transversus abdominis plane block with regard to pain relief and its duration of action after cesarean delivery. Between April 2015 and August 2015, we randomized 76 patients scheduled for elective cesarean delivery under spinal anesthesia to receive the quadratus lumborum block or the transversus abdominis plane block for postoperative pain relief. This trial was registered prospectively (NCT 02489851) [corrected]. Patients in the quadratus lumborum block group used significantly less morphine than the transversus abdominis plane block group (P consumption and demands than transversus abdominis plane blocks after cesarean section. This effect was observed up to 48 hours postoperatively.

[THE TECHNOLOGY "CELL BLOCK" IN CYTOLOGICAL PRACTICE].

Science.gov (United States)

Volchenko, N N; Borisova, O V; Baranova, I B

2015-08-01

The article presents summary information concerning application of "cell block" technology in cytological practice. The possibilities of implementation of various modern techniques (immune cytochemnical analysis. FISH, CISH, polymerase chain reaction) with application of "cell block" method are demonstrated. The original results of study of "cell block" technology made with gelatin, AgarCyto and Shadon Cyoblock set are presented. The diagnostic effectiveness of "cell block" technology and common cytological smear and also immune cytochemical analysis on samples of "cell block" technology and fluid cytology were compared. Actually application of "cell block" technology is necessary for ensuring preservation of cell elements for subsequent immune cytochemical and molecular genetic analysis.

21 CFR 520.1448a - Monensin blocks.

Science.gov (United States)

2010-04-01

...) Limitations. Block to be fed free choice to pasture cattle (slaughter, stocker, feeder, and dairy and beef.... Blocks to be fed free choice to pasture cattle (slaughter, stocker, feeder, and dairy and beef.... Blocks to be fed free choice to pasture cattle (slaughter, stocker, and feeder). Provide at least 1 block...

Approximating the imbibition and absorption behavior of a distribution of matrix blocks by an equivalent spherical block

International Nuclear Information System (INIS)

Zimmerman, R.W.; Bodvarsson, G.S.

1994-03-01

A theoretical study is presented of the effect of matrix block shape and matrix block size distribution on liquid imbibition and solute absorption in a fractured rock mass. It is shown that the behavior of an individual irregularly-shaped matrix block can be modeled with reasonable accuracy by using the results for a spherical matrix block, if one uses an effective radius a = 3V/A, where V is the volume of the block and A is its surface area. In the early-time regime of matrix imbibition, it is shown that a collection of blocks of different sizes can be modeled by a single equivalent block, with an equivalent radius of -1 > -1 , where the average is taken on a volumetrically-weighted basis. In an intermediate time regime, it is shown for the case where the radii are normally distributed that the equivalent radius is reasonably well approximated by the mean radius . In the long-time limit, where no equivalent radius can be rigorously defined, an asymptotic expression is derived for the cumulative diffusion as a function of the mean and the standard deviation of the radius distribution function

Application of interconnected porous hydroxyapatite ceramic block for onlay block bone grafting in implant treatment: A case report.

Science.gov (United States)

Ohta, Kouji; Tada, Misato; Ninomiya, Yoshiaki; Kato, Hiroki; Ishida, Fumi; Abekura, Hitoshi; Tsuga, Kazuhiro; Takechi, Masaaki

2017-12-01

Autogenous block bone grafting as treatment for alveolar ridge atrophy has various disadvantages, including a limited availability of sufficiently sized and shaped grafts, donor site morbidity and resorption of the grafted bone. As a result, interconnected porous hydroxyapatite ceramic (IP-CHA) materials with high porosity have been developed and used successfully in orthopedic cases. To the best of the author's knowledge, this is the first report of clinical application of an IP-CHA block for onlay grafting for implant treatment in a patient with horizontal alveolar atrophy. The present study performed onlay block grafting using an IP-CHA block to restore bone volume for implant placement in the alveolar ridge area without collecting autogenous bone. Dental X-ray findings revealed that the border of the IP-CHA block became increasingly vague over the 3-year period, whereas CT scanning revealed that the gap between the block and bone had a smooth transition, indicating that IP-CHA improved the process of integration with host bone. In follow-up examinations over a period of 5 years, the implants and superstructures had no problems. An IP-CHA block may be useful as a substitute for onlay block bone grafting in implant treatment.

Ultrasound guided TAP block versus ultrasound guided caudal block for pain relief in children undergoing lower abdominal surgeries

Directory of Open Access Journals (Sweden)

Wafaa Mohamed Alsadek

2015-04-01

Conclusion: TAP block and caudal block under ultrasound guidance proved to be safe with no recorded complications either intra or postoperatively. Patient and parent satisfaction was markedly observed in case of TAP block.

Naming Block Structures: A Multimodal Approach

Science.gov (United States)

Cohen, Lynn; Uhry, Joanna

2011-01-01

This study describes symbolic representation in block play in a culturally diverse suburban preschool classroom. Block play is "multimodal" and can allow children to experiment with materials to represent the world in many forms of literacy. Combined qualitative and quantitative data from seventy-seven block structures were collected and analyzed.…

21 CFR 882.5070 - Bite block.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Bite block. 882.5070 Section 882.5070 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Therapeutic Devices § 882.5070 Bite block. (a) Identification. A bite block...

Using Interference to Block RFID Tags

DEFF Research Database (Denmark)

Krigslund, Rasmus; Popovski, Petar; Pedersen, Gert Frølund

We propose a novel method to block RFID tags from responding, using intentional interference. We focus on the experimental evaluation, where we impose interference on the download and uplink, respectively. The results are positive, where modulated CCI shows most effective to block a tag.......We propose a novel method to block RFID tags from responding, using intentional interference. We focus on the experimental evaluation, where we impose interference on the download and uplink, respectively. The results are positive, where modulated CCI shows most effective to block a tag....

Pectoralis-serratus interfascial plane block vs thoracic paravertebral block for unilateral radical mastectomy with axillary evacuation.

Science.gov (United States)

Hetta, Diab Fuad; Rezk, Khalid Mohammed

2016-11-01

The aim of this study was to evaluate the analgesic efficacy and safety of pectoralis-serratus interfascial plane block in comparison with thoracic paravertebral block for postmastectomy pain. A prospective randomized controlled study. Tertiary center, university hospital. Sixty-four adult women, American Society of Anesthesiologists physical status classes I, II, and III, scheduled for unilateral modified radical mastectomy with axillary evacuation. Patients were randomized to receive either pectoralis-serratus interfascial plane block, PS group (n=32), or thoracic paravertebral block, PV group (n=32). Twenty-four-hour morphine consumption and the time to rescue analgesic were recorded. The pain intensity evaluated by visual analog scale (VAS) score at 0, 2, 4, 8, 16, and 24hours postoperatively was also recorded. The median (interquartile range) postoperative 24-hour morphine consumption was significantly increased in PS group in comparison to PV group (PS vs PV), 20 mg (16-23 mg) vs 12 mg (10-14 mg) (Pplane block was safe and easy to perform and decreased intensity of postmastectomy pain, but it was inferior to thoracic paravertebral block. Copyright © 2016 Elsevier Inc. All rights reserved.

Ground reaction curve based upon block theory

International Nuclear Information System (INIS)

Yow, J.L. Jr.; Goodman, R.E.

1985-09-01

Discontinuities in a rock mass can intersect an excavation surface to form discrete blocks (keyblocks) which can be unstable. Once a potentially unstable block is identified, the forces affecting it can be calculated to assess its stability. The normal and shear stresses on each block face before displacement are calculated using elastic theory and are modified in a nonlinear way by discontinuity deformations as the keyblock displaces. The stresses are summed into resultant forces to evaluate block stability. Since the resultant forces change with displacement, successive increments of block movement are examined to see whether the block ultimately becomes stable or fails. Two-dimensional (2D) and three-dimensional (3D) analytic models for the stability of simple pyramidal keyblocks were evaluated. Calculated stability is greater for 3D analyses than for 2D analyses. Calculated keyblock stability increases with larger in situ stress magnitudes, larger lateral stress ratios, and larger shear strengths. Discontinuity stiffness controls blocks displacement more strongly than it does stability itself. Large keyblocks are less stable than small ones, and stability increases as blocks become more slender

Strength and deformability of hollow concrete blocks: correlation of block and cylindrical sample test results

OpenAIRE

Barbosa, C. S.; Hanai, J.B.

2009-01-01

This paper deals with correlations among mechanical properties of hollow blocks and those of concrete used to make them. Concrete hollow blocks and test samples were moulded with plastic consistency concrete, to assure the same material in all cases, in three diferente levels of strength (nominally 10 N/mm², 20 N/mm² and 30 N/mm²). The mechanical properties and structural behaviour in axial compression and tension tests were determined by standard tests in blocks and cylinders. Stress and str...

Encoders for block-circulant LDPC codes

Science.gov (United States)

Divsalar, Dariush (Inventor); Abbasfar, Aliazam (Inventor); Jones, Christopher R. (Inventor); Dolinar, Samuel J. (Inventor); Thorpe, Jeremy C. (Inventor); Andrews, Kenneth S. (Inventor); Yao, Kung (Inventor)

2009-01-01

Methods and apparatus to encode message input symbols in accordance with an accumulate-repeat-accumulate code with repetition three or four are disclosed. Block circulant matrices are used. A first method and apparatus make use of the block-circulant structure of the parity check matrix. A second method and apparatus use block-circulant generator matrices.

How to block and tackle the face.

Science.gov (United States)

Zide, B M; Swift, R

1998-03-01

Regional blocking techniques as noted in dentistry, anesthesia, and anatomy texts may result in inconsistent and imperfect analgesia when needed for facial aesthetic surgery. The advent of laser facial surgery and more complicated aesthetic facial procedures has thus increased the demand for anesthesia support. Surgeons should know a fail-safe method of nerve blocks. Fresh cadaver dissections are used to demonstrate a series of eight regional nerve-blocking routes. This sequence of bilateral blocks will routinely provide profound full facial anesthesia. Certain groupings of blocks are effective for perioral or periorbital laser surgery.

Amphiphilic block copolymers for drug delivery.

Science.gov (United States)

Adams, Monica L; Lavasanifar, Afsaneh; Kwon, Glen S

2003-07-01

Amphiphilic block copolymers (ABCs) have been used extensively in pharmaceutical applications ranging from sustained-release technologies to gene delivery. The utility of ABCs for delivery of therapeutic agents results from their unique chemical composition, which is characterized by a hydrophilic block that is chemically tethered to a hydrophobic block. In aqueous solution, polymeric micelles are formed via the association of ABCs into nanoscopic core/shell structures at or above the critical micelle concentration. Upon micellization, the hydrophobic core regions serve as reservoirs for hydrophobic drugs, which may be loaded by chemical, physical, or electrostatic means, depending on the specific functionalities of the core-forming block and the solubilizate. Although the Pluronics, composed of poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide), are the most widely studied ABC system, copolymers containing poly(L-amino acid) and poly(ester) hydrophobic blocks have also shown great promise in delivery applications. Because each ABC has unique advantages with respect to drug delivery, it may be possible to choose appropriate block copolymers for specific purposes, such as prolonging circulation time, introduction of targeting moieties, and modification of the drug-release profile. ABCs have been used for numerous pharmaceutical applications including drug solubilization/stabilization, alteration of the pharmacokinetic profile of encapsulated substances, and suppression of multidrug resistance. The purpose of this minireview is to provide a concise, yet detailed, introduction to the use of ABCs and polymeric micelles as delivery agents as well as to highlight current and past work in this area. Copyright 2003 Wiley-Liss, Inc. and the American Pharmacists Association

Which Ultrasound-Guided Sciatic Nerve Block Strategy Works Faster? Prebifurcation or Separate Tibial-Peroneal Nerve Block? A Randomized Clinical Trial.

Science.gov (United States)

Faiz, Seyed Hamid Reza; Imani, Farnad; Rahimzadeh, Poupak; Alebouyeh, Mahmoud Reza; Entezary, Saeed Reza; Shafeinia, Amineh

2017-08-01

Peripheral nerve block is an accepted method in lower limb surgeries regarding its convenience and good tolerance by the patients. Quick performance and fast sensory and motor block are highly demanded in this method. The aim of the present study was to compare 2 different methods of sciatic and tibial-peroneal nerve block in lower limb surgeries in terms of block onset. In this clinical trial, 52 candidates for elective lower limb surgery were randomly divided into 2 groups: sciatic nerve block before bifurcation (SG; n = 27) and separate tibial-peroneal nerve block (TPG; n = 25) under ultrasound plus nerve stimulator guidance. The mean duration of block performance, as well as complete sensory and motor block, was recorded and compared between the groups. The mean duration of complete sensory block in the SG and TPG groups was 35.4 ± 4.1 and 24.9 ± 4.2 minutes, respectively, which was significantly lower in the TPG group (P = 0.001). The mean duration of complete motor block in the SG and TPG groups was 63.3 ± 4.4 and 48.4 ± 4.6 minutes, respectively, which was significantly lower in the TPG group (P = 0.001). No nerve injuries, paresthesia, or other possible side effects were reported in patients. According to the present study, it seems that TPG shows a faster sensory and motor block than SG.

Harmony of spinning conformal blocks

Energy Technology Data Exchange (ETDEWEB)

Schomerus, Volker [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Theory Group; Sobko, Evgeny [Stockholm Univ. (Sweden); Nordita, Stockholm (Sweden); Isachenkov, Mikhail [Weizmann Institute of Science, Rehovoth (Israel). Dept. of Particle Physics and Astrophysics

2016-12-07

Conformal blocks for correlation functions of tensor operators play an increasingly important role for the conformal bootstrap programme. We develop a universal approach to such spinning blocks through the harmonic analysis of certain bundles over a coset of the conformal group. The resulting Casimir equations are given by a matrix version of the Calogero-Sutherland Hamiltonian that describes the scattering of interacting spinning particles in a 1-dimensional external potential. The approach is illustrated in several examples including fermionic seed blocks in 3D CFT where they take a very simple form.

PEO-related block copolymer surfactants

DEFF Research Database (Denmark)

Mortensen, K.

2001-01-01

Non-ionic block copolymer systems based on hydrophilic poly(ethylene oxide) and more hydrophobic co-polymer blocks are used intensively in a variety of industrial and personal applications. A brief description on the applications is presented. The physical properties of more simple model systems...... of such PEG-based block copolymers in aqueous suspensions are reviewed. Based on scattering experiments using either X-ray or neutrons, the phase behavior is characterized, showing that the thermo-reversible gelation is a result of micellar ordering into mesoscopic crystalline phases of cubic, hexagonal...

Harmony of spinning conformal blocks

Energy Technology Data Exchange (ETDEWEB)

Schomerus, Volker [DESY Hamburg, Theory Group,Notkestraße 85, 22607 Hamburg (Germany); Sobko, Evgeny [Nordita and Stockholm University,Roslagstullsbacken 23, SE-106 91 Stockholm (Sweden); Isachenkov, Mikhail [Department of Particle Physics and Astrophysics, Weizmann Institute of Science,Rehovot 7610001 (Israel)

2017-03-15

Conformal blocks for correlation functions of tensor operators play an increasingly important role for the conformal bootstrap programme. We develop a universal approach to such spinning blocks through the harmonic analysis of certain bundles over a coset of the conformal group. The resulting Casimir equations are given by a matrix version of the Calogero-Sutherland Hamiltonian that describes the scattering of interacting spinning particles in a 1-dimensional external potential. The approach is illustrated in several examples including fermionic seed blocks in 3D CFT where they take a very simple form.

Metallo-supramolecular block copolymer micelles

NARCIS (Netherlands)

Gohy, J.M.W.

2009-01-01

Supramolecular copolymers have become of increasing interest in recent years in the search for new materials with tunable properties. In particular, metallo-supramolecular block copolymers in which metal-ligand complexes are introduced in block copolymer architectures, have known important progress,

Inferior alveolar nerve block: Alternative technique.

Science.gov (United States)

Thangavelu, K; Kannan, R; Kumar, N Senthil

2012-01-01

Inferior alveolar nerve block (IANB) is a technique of dental anesthesia, used to produce anesthesia of the mandibular teeth, gingivae of the mandible and lower lip. The conventional IANB is the most commonly used the nerve block technique for achieving local anesthesia for mandibular surgical procedures. In certain cases, however, this nerve block fails, even when performed by the most experienced clinician. Therefore, it would be advantageous to find an alternative simple technique. The objective of this study is to find an alternative inferior alveolar nerve block that has a higher success rate than other routine techniques. To this purpose, a simple painless inferior alveolar nerve block was designed to anesthetize the inferior alveolar nerve. This study was conducted in Oral surgery department of Vinayaka Mission's dental college Salem from May 2009 to May 2011. Five hundred patients between the age of 20 years and 65 years who required extraction of teeth in mandible were included in the study. Out of 500 patients 270 were males and 230 were females. The effectiveness of the IANB was evaluated by using a sharp dental explorer in the regions innervated by the inferior alveolar, lingual, and buccal nerves after 3, 5, and 7 min, respectively. This study concludes that inferior alveolar nerve block is an appropriate alternative nerve block to anesthetize inferior alveolar nerve due to its several advantages.

Diaphragm-Sparing Nerve Blocks for Shoulder Surgery.

Science.gov (United States)

Tran, De Q H; Elgueta, Maria Francisca; Aliste, Julian; Finlayson, Roderick J

Shoulder surgery can result in significant postoperative pain. Interscalene brachial plexus blocks (ISBs) constitute the current criterion standard for analgesia but may be contraindicated in patients with pulmonary pathology due to the inherent risk of phrenic nerve block and symptomatic hemidiaphragmatic paralysis. Although ultrasound-guided ISB with small volumes (5 mL), dilute local anesthetic (LA) concentrations, and LA injection 4 mm lateral to the brachial plexus have been shown to reduce the risk of phrenic nerve block, no single intervention can decrease its incidence below 20%. Ultrasound-guided supraclavicular blocks with LA injection posterolateral to the brachial plexus may anesthetize the shoulder without incidental diaphragmatic dysfunction, but further confirmatory trials are required. Ultrasound-guided C7 root blocks also seem to offer an attractive, diaphragm-sparing alternative to ISB. However, additional large-scale studies are needed to confirm their efficacy and to quantify the risk of periforaminal vascular breach. Combined axillary-suprascapular nerve blocks may provide adequate postoperative analgesia for minor shoulder surgery but do not compare favorably to ISB for major surgical procedures. One intriguing solution lies in the combined use of infraclavicular brachial plexus blocks and suprascapular nerve blocks. Theoretically, the infraclavicular approach targets the posterior and lateral cords, thus anesthetizing the axillary nerve (which supplies the anterior and posterior shoulder joint), as well as the subscapular and lateral pectoral nerves (both of which supply the anterior shoulder joint), whereas the suprascapular nerve block anesthetizes the posterior shoulder. Future randomized trials are required to validate the efficacy of combined infraclavicular-suprascapular blocks for shoulder surgery.

Brief reports: a clinical evaluation of block characteristics using one milliliter 2% lidocaine in ultrasound-guided axillary brachial plexus block.

LENUS (Irish Health Repository)

O'Donnell, Brian

2010-09-01

We report onset and duration of ultrasound-guided axillary brachial plexus block using 1 mL of 2% lidocaine with 1:200,000 epinephrine per nerve (total local anesthetic volume 4 mL). Block performance time, block onset time, duration of surgery, and block duration were measured. Seventeen consecutive patients were recruited. The mean (SD) block performance and onset times were 271 (67.9) seconds and 9.7 (3.7) minutes, respectively. Block duration was 160.8 (30.7) minutes. All operations were performed using regional anesthesia alone. The duration of anesthesia obtained is sufficient for most ambulatory hand surgery.