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Sample records for biased mitotic gene

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

    DEFF Research Database (Denmark)

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

    2014-01-01

    Mitotic index is an important component of histologic grade and has an etiologic role in breast tumorigenesis. Several small candidate gene studies have reported associations between variation in mitotic genes and breast cancer risk. We measured associations between 2156 single nucleotide polymor...

  2. Identification of Drosophila mitotic genes by combining co-expression analysis and RNA interference.

    Directory of Open Access Journals (Sweden)

    Maria Patrizia Somma

    2008-07-01

    Full Text Available RNAi screens have, to date, identified many genes required for mitotic divisions of Drosophila tissue culture cells. However, the inventory of such genes remains incomplete. We have combined the powers of bioinformatics and RNAi technology to detect novel mitotic genes. We found that Drosophila genes involved in mitosis tend to be transcriptionally co-expressed. We thus constructed a co-expression-based list of 1,000 genes that are highly enriched in mitotic functions, and we performed RNAi for each of these genes. By limiting the number of genes to be examined, we were able to perform a very detailed phenotypic analysis of RNAi cells. We examined dsRNA-treated cells for possible abnormalities in both chromosome structure and spindle organization. This analysis allowed the identification of 142 mitotic genes, which were subdivided into 18 phenoclusters. Seventy of these genes have not previously been associated with mitotic defects; 30 of them are required for spindle assembly and/or chromosome segregation, and 40 are required to prevent spontaneous chromosome breakage. We note that the latter type of genes has never been detected in previous RNAi screens in any system. Finally, we found that RNAi against genes encoding kinetochore components or highly conserved splicing factors results in identical defects in chromosome segregation, highlighting an unanticipated role of splicing factors in centromere function. These findings indicate that our co-expression-based method for the detection of mitotic functions works remarkably well. We can foresee that elaboration of co-expression lists using genes in the same phenocluster will provide many candidate genes for small-scale RNAi screens aimed at completing the inventory of mitotic proteins.

  3. Brd4 Marks Select Genes on Mitotic Chromatin and Directs Postmitotic Transcription

    OpenAIRE

    Dey, Anup; Nishiyama, Akira; Karpova, Tatiana; McNally, James; Ozato, Keiko

    2009-01-01

    On entry into mitosis, many transcription factors dissociate from chromatin, resulting in global transcriptional shutdown. During mitosis, some genes are marked to ensure the inheritance of their expression in the next generation of cells. The nature of mitotic gene marking, however, has been obscure. Brd4 is a double bromodomain protein that localizes to chromosomes during mitosis and is implicated in holding mitotic memory. In interphase, Brd4 interacts with P-TEFb and functions as a global...

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

    Science.gov (United States)

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

    2014-01-01

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

  5. Genes involved in centrosome-independent mitotic spindle assembly in Drosophila S2 cells.

    Science.gov (United States)

    Moutinho-Pereira, Sara; Stuurman, Nico; Afonso, Olga; Hornsveld, Marten; Aguiar, Paulo; Goshima, Gohta; Vale, Ronald D; Maiato, Helder

    2013-12-01

    Animal mitotic spindle assembly relies on centrosome-dependent and centrosome-independent mechanisms, but their relative contributions remain unknown. Here, we investigated the molecular basis of the centrosome-independent spindle assembly pathway by performing a whole-genome RNAi screen in Drosophila S2 cells lacking functional centrosomes. This screen identified 197 genes involved in acentrosomal spindle assembly, eight of which had no previously described mitotic phenotypes and produced defective and/or short spindles. All 197 genes also produced RNAi phenotypes when centrosomes were present, indicating that none were entirely selective for the acentrosomal pathway. However, a subset of genes produced a selective defect in pole focusing when centrosomes were absent, suggesting that centrosomes compensate for this shape defect. Another subset of genes was specifically associated with the formation of multipolar spindles only when centrosomes were present. We further show that the chromosomal passenger complex orchestrates multiple centrosome-independent processes required for mitotic spindle assembly/maintenance. On the other hand, despite the formation of a chromosome-enriched RanGTP gradient, S2 cells depleted of RCC1, the guanine-nucleotide exchange factor for Ran on chromosomes, established functional bipolar spindles. Finally, we show that cells without functional centrosomes have a delay in chromosome congression and anaphase onset, which can be explained by the lack of polar ejection forces. Overall, these findings establish the constitutive nature of a centrosome-independent spindle assembly program and how this program is adapted to the presence/absence of centrosomes in animal somatic cells.

  6. Selection and Biased Gene Conversion in a Multigene Family: Consequences of Interallelic Bias and Threshold Selection

    OpenAIRE

    Walsh, James Bruce

    1986-01-01

    In a previous paper, I investigated the interactions in a gene family of additive selection and biased gene conversion in a finite population when conversion events are rare. Here I extend my "weak-conversion limit" model by allowing biased interallelic conversion (conversion between alleles at the same locus) of arbitrary frequency and various threshold selection schemes for rare interlocus conversion events. I suggest that it is not unreasonable for gene families to experience threshold fit...

  7. Effects of the rad52 gene on recombination in Saccharomyces cerevisiae. [Comparison of. gamma. -, uv-induced meiotic and spontaneous mitotic recombination

    Energy Technology Data Exchange (ETDEWEB)

    Prakash, S.; Prakash, L.; Burke, W.; Montelone, B.A.

    1979-01-01

    Effects of the rad52 mutation in Saccharomyces cerevisiae on meiotic, ..gamma..-ray-induced, uv-induced, and spontaneous mitotic recombination were studied. The rad52/rad52 diploids undergo premeiotic DNA synthesis; sporulation occurs but inviable spores are produced. Intra- and intergenic recombination during meiosis were examined in cells transferred from sporulation medium to vegetative medium at different time intervals. No intragenic recombination was observed at the hisl-1/hisl-315 and trp5-2/trp5-48 heteroalleles. Gene-centromere recombination was also not observed in rad52/rad52 diploids. No ..gamma..-ray-induced intragenic mitotic recombination is seen in rad52/rad52 diploids and uv-induced intragenic recombination is greatly reduced. However, spontaneous mitotic recombination is not similarly affected. The RAD52 gene thus functions in recombination in meiosis and in ..gamma..-ray and uv-induced mitotic recombination but not in spontaneous mitotic recombination.

  8. Human papillomavirus type 16 E7 perturbs DREAM to promote cellular proliferation and mitotic gene expression.

    Science.gov (United States)

    DeCaprio, J A

    2014-07-31

    The study of the small DNA tumor viruses continues to provide valuable new insights into oncogenesis and fundamental biological processes. Although much has already been revealed about how the human papillomaviruses (HPVs) can transform cells and contribute to cervical and oropharyngeal cancer, there clearly is much more to learn. In this issue of Oncogene, Pang et al., doi:10.1038/onc.2013.426, demonstrate that the high-risk HPV16 E7 oncogene can promote cellular proliferation by interacting with the DREAM (DP, RB-like, E2F and MuvB) complex at two distinct phases of the cell cycle. Consistent with earlier work, HPV16 E7 can bind to the retinoblastoma tumor suppressor (RB) family member p130 (RBL2) protein and promote its proteasome-mediated destruction thereby disrupting the DREAM complex and can prevent exit from the cell cycle into quiescence. In addition, they demonstrate that HPV16 E7 can bind to MuvB core complex in association with BMYB and FOXM1 and activate gene expression during the G2 and M phase of the cell cycle. Thus, HPV16 E7 acts to prevent exit from the cell cycle entry and promotes mitotic proliferation and may account for the high levels of FOXM1 often observed in poor-risk cervical cancers. PMID:24166507

  9. Human papillomavirus type 16 E7 perturbs DREAM to promote cellular proliferation and mitotic gene expression

    Science.gov (United States)

    DeCaprio, James A.

    2014-01-01

    Study of the small DNA tumor viruses continues to provide valuable new insights into oncogenesis and fundamental biological processes. While much has already been revealed about how the human papillomaviruses (HPVs) can transform cells and contribute to cervical and oropharyngeal cancer, there clearly is much more to learn. In this issue of Oncogene, Pang et al. demonstrate that the high-risk HPV16 E7 oncogene can promote cellular proliferation by interacting with the DREAM (DP, RB-like, E2F and MuvB) complex at two distinct phases of the cell cycle (1). Consistent with earlier work, HPV16 E7 can bind to the retinoblastoma tumor suppressor (RB) family member p130 (RBL2) protein and promote its proteasome-mediated destruction thereby disrupting the DREAM complex and prevent exit from the cell cycle into quiescence. In addition, they demonstrate that HPV16 E7 can bind to MuvB core complex in association with BMYB and FOXM1 and activate gene expression during the G2 and M phase of the cell cycle. Thus, HPV16 E7 acts to prevent exit from the cell cycle entry and promotes mitotic proliferation and may account for the high levels of FOXM1 often observed in poor risk cervical cancers. PMID:24166507

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

    Science.gov (United States)

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

    2014-05-30

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

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

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    Kimchi Strasser

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

  12. Biasogram: visualization of confounding technical bias in gene expression data

    DEFF Research Database (Denmark)

    Krzystanek, Marcin; Szallasi, Zoltan Imre; Eklund, Aron Charles

    2013-01-01

    Gene expression profiles of clinical cohorts can be used to identify genes that are correlated with a clinical variable of interest such as patient outcome or response to a particular drug. However, expression measurements are susceptible to technical bias caused by variation in extraneous factor...

  13. The relationship between codon usage bias and cold resistant genes

    International Nuclear Information System (INIS)

    This research is based on synonymous codon usage which has been well-known as a feature that affects typical expression level of protein in an organism. Different organisms prefer different codons for same amino acid and this is called Codon Usage Bias (CUB). The codon usage directly affects the level or even direction of changes in protein expression in responses to environmental stimuli. Cold stress is a major abiotic factor that limits the agricultural productivity of plants. In the recent study CUB has been studied in Arabidopsis thaliana cold resistant and housekeeping genes and their homologs in rice (Oryza sativa) to understand the cold stress and housekeeping genes relation with CUB. Six cold resistant and three housekeeping genes in Arabidopsis thaliana and their homologs in rice, were subjected to CUB analysis. The three cold resistant genes (DREB1B, RCI and MYB15) showed more than 50% (52%, 61% and 66% respectively) similar codon usage bias for Arabidopsis thaliana and rice. On the other hand three cold resistant genes (MPK3, ICE1 and ZAT12) showed less than 50% (38%, 38% and 47% respectively) similar codon usage bias for Arabidopsis thaliana and rice. The three housekeeping genes (Actin, Tubulin and Ubiquitin) showed 76% similar codon usage bias for Arabidopsis thaliana and rice. This study will help to manage the plant gene expression through codon optimization under the cold stress. (author)

  14. No accelerated rate of protein evolution in male-biased Drosophila pseudoobscura genes.

    OpenAIRE

    Metta, Muralidhar; Gudavalli, Rambabu; Gibert, Jean-Michel; Schlotterer, Christian

    2006-01-01

    Sexually dimorphic traits are often subject to diversifying selection. Genes with a male-biased gene expression also are probably affected by sexual selection and have a high rate of protein evolution. We used SAGE to measure sex-biased gene expression in Drosophila pseudoobscura. Consistent with previous results from D. melanogaster, a larger number of genes were male biased (402 genes) than female biased (138 genes). About 34% of the genes changed the sex-related expression pattern between ...

  15. Hotspots of biased nucleotide substitutions in human genes.

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    Jonas Berglund

    2009-01-01

    Full Text Available Genes that have experienced accelerated evolutionary rates on the human lineage during recent evolution are candidates for involvement in human-specific adaptations. To determine the forces that cause increased evolutionary rates in certain genes, we analyzed alignments of 10,238 human genes to their orthologues in chimpanzee and macaque. Using a likelihood ratio test, we identified protein-coding sequences with an accelerated rate of base substitutions along the human lineage. Exons evolving at a fast rate in humans have a significant tendency to contain clusters of AT-to-GC (weak-to-strong biased substitutions. This pattern is also observed in noncoding sequence flanking rapidly evolving exons. Accelerated exons occur in regions with elevated male recombination rates and exhibit an excess of nonsynonymous substitutions relative to the genomic average. We next analyzed genes with significantly elevated ratios of nonsynonymous to synonymous rates of base substitution (dN/dS along the human lineage, and those with an excess of amino acid replacement substitutions relative to human polymorphism. These genes also show evidence of clusters of weak-to-strong biased substitutions. These findings indicate that a recombination-associated process, such as biased gene conversion (BGC, is driving fixation of GC alleles in the human genome. This process can lead to accelerated evolution in coding sequences and excess amino acid replacement substitutions, thereby generating significant results for tests of positive selection.

  16. Abundance of female-biased and paucity of male-biased somatically expressed genes on the mouse X-chromosome

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    Reinius Björn

    2012-11-01

    Full Text Available Abstract Background Empirical evaluations of sexually dimorphic expression of genes on the mammalian X-chromosome are needed to understand the evolutionary forces and the gene-regulatory mechanisms controlling this chromosome. We performed a large-scale sex-bias expression analysis of genes on the X-chromosome in six different somatic tissues from mouse. Results Our results show that the mouse X-chromosome is enriched with female-biased genes and depleted of male-biased genes. This suggests that feminisation as well as de-masculinisation of the X-chromosome has occurred in terms of gene expression in non-reproductive tissues. Several mechanisms may be responsible for the control of female-biased expression on chromosome X, and escape from X-inactivation is a main candidate. We confirmed escape in case of Tmem29 using RNA-FISH analysis. In addition, we identified novel female-biased non-coding transcripts located in the same female-biased cluster as the well-known coding X-inactivation escapee Kdm5c, likely transcribed from the transition-region between active and silenced domains. We also found that previously known escapees only partially explained the overrepresentation of female-biased X-genes, particularly for tissue-specific female-biased genes. Therefore, the gene set we have identified contains tissue-specific escapees and/or genes controlled by other sexually skewed regulatory mechanisms. Analysis of gene age showed that evolutionarily old X-genes (>100 myr, preceding the radiation of placental mammals are more frequently female-biased than younger genes. Conclusion Altogether, our results have implications for understanding both gene regulation and gene evolution of mammalian X-chromosomes, and suggest that the final result in terms of the X-gene composition (masculinisation versus feminisation is a compromise between different evolutionary forces acting on reproductive and somatic tissues.

  17. Abrupt onset of mutations in a developmentally regulated gene during terminal differentiation of post-mitotic photoreceptor neurons in mice.

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    Ivette M Sandoval

    Full Text Available For sensitive detection of rare gene repair events in terminally differentiated photoreceptors, we generated a knockin mouse model by replacing one mouse rhodopsin allele with a form of the human rhodopsin gene that causes a severe, early-onset form of retinitis pigmentosa. The human gene contains a premature stop codon at position 344 (Q344X, cDNA encoding the enhanced green fluorescent protein (EGFP at its 3' end, and a modified 5' untranslated region to reduce translation rate so that the mutant protein does not induce retinal degeneration. Mutations that eliminate the stop codon express a human rhodopsin-EGFP fusion protein (hRho-GFP, which can be readily detected by fluorescence microscopy. Spontaneous mutations were observed at a frequency of about one per retina; in every case, they gave rise to single fluorescent rod cells, indicating that each mutation occurred during or after the last mitotic division. Additionally, the number of fluorescent rods did not increase with age, suggesting that the rhodopsin gene in mature rod cells is less sensitive to mutation than it is in developing rods. Thus, there is a brief developmental window, coinciding with the transcriptional activation of the rhodopsin locus, in which somatic mutations of the rhodopsin gene abruptly begin to appear.

  18. Mitotic dynamics

    Institute of Scientific and Technical Information of China (English)

    唐孝威

    1996-01-01

    A new model for mitotic dynamics of eukaryotic cells is proposed. In the kinetochore mo-tor-midzone motor model two kinds of motors, the kinetochore motors and the midzone motors, play important roles in chromosome movement. Using this model the chromosome congression during prometaphase, the chromosome oscillation during metaphase and the chromatid segregation during anaphase are described in a unified way.

  19. In silico analysis of deleterious single nucleotide polymorphisms in human BUB1 mitotic checkpoint serine/threonine kinase B gene.

    Science.gov (United States)

    Akhoundi, Fatemeh; Parvaneh, Nikpour; Modjtaba, Emadi-Baygi

    2016-09-01

    One of the major challenges in the analysis of human genetic variation is to distinguish mutations that are functionally neutral from those that contribute to disease. BubR1 is a key protein mediating spindle-checkpoint activation that plays a role in the inhibition of the anaphase-promoting complex/cyclosome (APC/C), delaying the onset of anaphase and ensuring proper chromosome segregation. Owing to the importance of BUB1B gene in mitotic checkpoint a functional analysis using different in silico approaches was undertaken to explore the possible associations between genetic mutations and phenotypic variation. In this work we found that 3 nsSNPs I82N, P334L and R814H have a functional effect on protein function and stability. A literature search revealed that R814H was already implicated in human diseases. Additionally, 2 SNPs in the 5' UTR region was predicted to exhibit a pattern change in the internal ribosome entry site (IRES), and eight MicroRNA binding sites were found to be highly affected due to 3' UTR SNPs. These in silico predictions will provide useful information in selecting the target SNPs that are likely to have functional impact on the BUB1B gene. PMID:27331020

  20. p21 as a transcriptional co-repressor of S-phase and mitotic control genes.

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    Nuria Ferrándiz

    Full Text Available It has been previously described that p21 functions not only as a CDK inhibitor but also as a transcriptional co-repressor in some systems. To investigate the roles of p21 in transcriptional control, we studied the gene expression changes in two human cell systems. Using a human leukemia cell line (K562 with inducible p21 expression and human primary keratinocytes with adenoviral-mediated p21 expression, we carried out microarray-based gene expression profiling. We found that p21 rapidly and strongly repressed the mRNA levels of a number of genes involved in cell cycle and mitosis. One of the most strongly down-regulated genes was CCNE2 (cyclin E2 gene. Mutational analysis in K562 cells showed that the N-terminal region of p21 is required for repression of gene expression of CCNE2 and other genes. Chromatin immunoprecipitation assays indicated that p21 was bound to human CCNE2 and other p21-repressed genes gene in the vicinity of the transcription start site. Moreover, p21 repressed human CCNE2 promoter-luciferase constructs in K562 cells. Bioinformatic analysis revealed that the CDE motif is present in most of the promoters of the p21-regulated genes. Altogether, the results suggest that p21 exerts a repressive effect on a relevant number of genes controlling S phase and mitosis. Thus, p21 activity as inhibitor of cell cycle progression would be mediated not only by the inhibition of CDKs but also by the transcriptional down-regulation of key genes.

  1. Transcript levels of the Saccharomyes cerevisiae DNA repair gene RAD23 increase in response to UV light and in meiosis but remain constant in the mitotic cell cycle.

    Science.gov (United States)

    Madura, K; Prakash, S

    1990-08-25

    The RAD23 gene of Saccharomyces cerevisiae is required for excision-repair of UV damaged DNA. In this paper, we determine the location of the RAD23 gene in a cloned DNA fragment, identify the 1.6 kb RAD23 transcript, and examine RAD23 transcript levels in UV damaged cells, during the mitotic cell cycle, and in meiosis. The RAD23 mRNA levels are elevated 5-fold between 30 to 60 min after 37 J/m2 of UV light. RAD23 mRNA levels rise over 6-fold during meiosis at a stage coincident with high levels of genetic recombination. This response is specific to sporulation competent MATa/MAT alpha diploid cells, and is not observed in asporogenous MATa/MATa diploids. RAD23 mRNA levels, however, remain constant during the mitotic cell cycle.

  2. Dopaminergic genes predict individual differences in susceptibility to confirmation bias.

    Science.gov (United States)

    Doll, Bradley B; Hutchison, Kent E; Frank, Michael J

    2011-04-20

    The striatum is critical for the incremental learning of values associated with behavioral actions. The prefrontal cortex (PFC) represents abstract rules and explicit contingencies to support rapid behavioral adaptation in the absence of cumulative experience. Here we test two alternative models of the interaction between these systems, and individual differences thereof, when human subjects are instructed with prior information about reward contingencies that may or may not be accurate. Behaviorally, subjects are overly influenced by prior instructions, at the expense of learning true reinforcement statistics. Computational analysis found that this pattern of data is best accounted for by a confirmation bias mechanism in which prior beliefs--putatively represented in PFC--influence the learning that occurs in the striatum such that reinforcement statistics are distorted. We assessed genetic variants affecting prefrontal and striatal dopaminergic neurotransmission. A polymorphism in the COMT gene (rs4680), associated with prefrontal dopaminergic function, was predictive of the degree to which participants persisted in responding in accordance with prior instructions even as evidence against their veracity accumulated. Polymorphisms in genes associated with striatal dopamine function (DARPP-32, rs907094, and DRD2, rs6277) were predictive of learning from positive and negative outcomes. Notably, these same variants were predictive of the degree to which such learning was overly inflated or neglected when outcomes are consistent or inconsistent with prior instructions. These findings indicate dissociable neurocomputational and genetic mechanisms by which initial biases are strengthened by experience. PMID:21508242

  3. Sex-biased gene expression during head development in a sexually dimorphic stalk-eyed fly.

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    Gerald S Wilkinson

    Full Text Available Stalk-eyed flies (family Diopsidae are a model system for studying sexual selection due to the elongated and sexually dimorphic eye-stalks found in many species. These flies are of additional interest because their X chromosome is derived largely from an autosomal arm in other flies. To identify candidate genes required for development of dimorphic eyestalks and investigate how sex-biased expression arose on the novel X, we compared gene expression between males and females using oligonucleotide microarrays and RNA from developing eyestalk tissue or adult heads in the dimorphic diopsid, Teleopsis dalmanni. Microarray analysis revealed sex-biased expression for 26% of 3,748 genes expressed in eye-antennal imaginal discs and concordant sex-biased expression for 86 genes in adult heads. Overall, 415 female-biased and 482 male-biased genes were associated with dimorphic eyestalk development but not differential expression in the adult head. Functional analysis revealed that male-biased genes are disproportionately associated with growth and mitochondrial function while female-biased genes are associated with cell differentiation and patterning or are novel transcripts. With regard to chromosomal effects, dosage compensation occurs by elevated expression of X-linked genes in males. Genes with female-biased expression were more common on the X and less common on autosomes than expected, while male-biased genes exhibited no chromosomal pattern. Rates of protein evolution were lower for female-biased genes but higher for genes that moved on or off the novel X chromosome. These findings cannot be due to meiotic sex chromosome inactivation or by constraints associated with dosage compensation. Instead, they could be consistent with sexual conflict in which female-biased genes on the novel X act primarily to reduce eyespan in females while other genes increase eyespan in both sexes. Additional information on sex-biased gene expression in other tissues and

  4. CRISPR/Cas9-Mediated Gene Knock-Down in Post-Mitotic Neurons

    OpenAIRE

    Christoph Straub; Granger, Adam J.; Saulnier, Jessica L.; Sabatini, Bernardo L.

    2014-01-01

    The prokaryotic adaptive immune system CRISPR/Cas9 has recently been adapted for genome editing in eukaryotic cells. This technique allows for sequence-specific induction of double-strand breaks in genomic DNA of individual cells, effectively resulting in knock-out of targeted genes. It thus promises to be an ideal candidate for application in neuroscience where constitutive genetic modifications are frequently either lethal or ineffective due to adaptive changes of the brain. Here we use CRI...

  5. CRISPR/Cas9-mediated gene knock-down in post-mitotic neurons.

    Directory of Open Access Journals (Sweden)

    Christoph Straub

    Full Text Available The prokaryotic adaptive immune system CRISPR/Cas9 has recently been adapted for genome editing in eukaryotic cells. This technique allows for sequence-specific induction of double-strand breaks in genomic DNA of individual cells, effectively resulting in knock-out of targeted genes. It thus promises to be an ideal candidate for application in neuroscience where constitutive genetic modifications are frequently either lethal or ineffective due to adaptive changes of the brain. Here we use CRISPR/Cas9 to knock-out Grin1, the gene encoding the obligatory NMDA receptor subunit protein GluN1, in a sparse population of mouse pyramidal neurons. Within this genetically mosaic tissue, manipulated cells lack synaptic current mediated by NMDA-type glutamate receptors consistent with complete knock-out of the targeted gene. Our results show the first proof-of-principle demonstration of CRISPR/Cas9-mediated knock-down in neurons in vivo, where it can be a useful tool to study the function of specific proteins in neuronal circuits.

  6. Meiotic Interactors of a Mitotic Gene TAO3 Revealed by Functional Analysis of its Rare Variant.

    Science.gov (United States)

    Gupta, Saumya; Radhakrishnan, Aparna; Nitin, Rachana; Raharja-Liu, Pandu; Lin, Gen; Steinmetz, Lars M; Gagneur, Julien; Sinha, Himanshu

    2016-01-01

    Studying the molecular consequences of rare genetic variants has the potential to identify novel and hitherto uncharacterized pathways causally contributing to phenotypic variation. Here, we characterize the functional consequences of a rare coding variant of TAO3, previously reported to contribute significantly to sporulation efficiency variation in Saccharomyces cerevisiae During mitosis, the common TAO3 allele interacts with CBK1-a conserved NDR kinase. Both TAO3 and CBK1 are components of the RAM signaling network that regulates cell separation and polarization during mitosis. We demonstrate that the role of the rare allele TAO3(4477C) in meiosis is distinct from its role in mitosis by being independent of ACE2-a RAM network target gene. By quantitatively measuring cell morphological dynamics, and expressing the TAO3(4477C) allele conditionally during sporulation, we show that TAO3 has an early role in meiosis. This early role of TAO3 coincides with entry of cells into meiotic division. Time-resolved transcriptome analyses during early sporulation identified regulators of carbon and lipid metabolic pathways as candidate mediators. We show experimentally that, during sporulation, the TAO3(4477C) allele interacts genetically with ERT1 and PIP2, regulators of the tricarboxylic acid cycle and gluconeogenesis metabolic pathways, respectively. We thus uncover a meiotic functional role for TAO3, and identify ERT1 and PIP2 as novel regulators of sporulation efficiency. Our results demonstrate that studying the causal effects of genetic variation on the underlying molecular network has the potential to provide a more extensive understanding of the pathways driving a complex trait. PMID:27317780

  7. Meiotic Interactors of a Mitotic Gene TAO3 Revealed by Functional Analysis of its Rare Variant

    Directory of Open Access Journals (Sweden)

    Saumya Gupta

    2016-08-01

    Full Text Available Studying the molecular consequences of rare genetic variants has the potential to identify novel and hitherto uncharacterized pathways causally contributing to phenotypic variation. Here, we characterize the functional consequences of a rare coding variant of TAO3, previously reported to contribute significantly to sporulation efficiency variation in Saccharomyces cerevisiae. During mitosis, the common TAO3 allele interacts with CBK1—a conserved NDR kinase. Both TAO3 and CBK1 are components of the RAM signaling network that regulates cell separation and polarization during mitosis. We demonstrate that the role of the rare allele TAO3(4477C in meiosis is distinct from its role in mitosis by being independent of ACE2—a RAM network target gene. By quantitatively measuring cell morphological dynamics, and expressing the TAO3(4477C allele conditionally during sporulation, we show that TAO3 has an early role in meiosis. This early role of TAO3 coincides with entry of cells into meiotic division. Time-resolved transcriptome analyses during early sporulation identified regulators of carbon and lipid metabolic pathways as candidate mediators. We show experimentally that, during sporulation, the TAO3(4477C allele interacts genetically with ERT1 and PIP2, regulators of the tricarboxylic acid cycle and gluconeogenesis metabolic pathways, respectively. We thus uncover a meiotic functional role for TAO3, and identify ERT1 and PIP2 as novel regulators of sporulation efficiency. Our results demonstrate that studying the causal effects of genetic variation on the underlying molecular network has the potential to provide a more extensive understanding of the pathways driving a complex trait.

  8. Large Scale Gene Expression Meta-Analysis Reveals Tissue-Specific, Sex-Biased Gene Expression in Humans

    Science.gov (United States)

    Mayne, Benjamin T.; Bianco-Miotto, Tina; Buckberry, Sam; Breen, James; Clifton, Vicki; Shoubridge, Cheryl; Roberts, Claire T.

    2016-01-01

    The severity and prevalence of many diseases are known to differ between the sexes. Organ specific sex-biased gene expression may underpin these and other sexually dimorphic traits. To further our understanding of sex differences in transcriptional regulation, we performed meta-analyses of sex biased gene expression in multiple human tissues. We analyzed 22 publicly available human gene expression microarray data sets including over 2500 samples from 15 different tissues and 9 different organs. Briefly, by using an inverse-variance method we determined the effect size difference of gene expression between males and females. We found the greatest sex differences in gene expression in the brain, specifically in the anterior cingulate cortex, (1818 genes), followed by the heart (375 genes), kidney (224 genes), colon (218 genes), and thyroid (163 genes). More interestingly, we found different parts of the brain with varying numbers and identity of sex-biased genes, indicating that specific cortical regions may influence sexually dimorphic traits. The majority of sex-biased genes in other tissues such as the bladder, liver, lungs, and pancreas were on the sex chromosomes or involved in sex hormone production. On average in each tissue, 32% of autosomal genes that were expressed in a sex-biased fashion contained androgen or estrogen hormone response elements. Interestingly, across all tissues, we found approximately two-thirds of autosomal genes that were sex-biased were not under direct influence of sex hormones. To our knowledge this is the largest analysis of sex-biased gene expression in human tissues to date. We identified many sex-biased genes that were not under the direct influence of sex chromosome genes or sex hormones. These may provide targets for future development of sex-specific treatments for diseases.

  9. Codon Bias as a Means to Fine-Tune Gene Expression

    NARCIS (Netherlands)

    Quax, T.E.F.; Claassens, N.J.H.P.; Söll, D.; Oost, van der J.

    2015-01-01

    The redundancy of the genetic code implies that most amino acids are encoded by multiple synonymous codons. In all domains of life, a biased frequency of synonymous codons is observed at the genome level, in functionally related genes (e.g., in operons), and within single genes. Other codon bias var

  10. Genes with minimal phylogenetic information are problematic for coalescent analyses when gene tree estimation is biased.

    Science.gov (United States)

    Xi, Zhenxiang; Liu, Liang; Davis, Charles C

    2015-11-01

    The development and application of coalescent methods are undergoing rapid changes. One little explored area that bears on the application of gene-tree-based coalescent methods to species tree estimation is gene informativeness. Here, we investigate the accuracy of these coalescent methods when genes have minimal phylogenetic information, including the implementation of the multilocus bootstrap approach. Using simulated DNA sequences, we demonstrate that genes with minimal phylogenetic information can produce unreliable gene trees (i.e., high error in gene tree estimation), which may in turn reduce the accuracy of species tree estimation using gene-tree-based coalescent methods. We demonstrate that this problem can be alleviated by sampling more genes, as is commonly done in large-scale phylogenomic analyses. This applies even when these genes are minimally informative. If gene tree estimation is biased, however, gene-tree-based coalescent analyses will produce inconsistent results, which cannot be remedied by increasing the number of genes. In this case, it is not the gene-tree-based coalescent methods that are flawed, but rather the input data (i.e., estimated gene trees). Along these lines, the commonly used program PhyML has a tendency to infer one particular bifurcating topology even though it is best represented as a polytomy. We additionally corroborate these findings by analyzing the 183-locus mammal data set assembled by McCormack et al. (2012) using ultra-conserved elements (UCEs) and flanking DNA. Lastly, we demonstrate that when employing the multilocus bootstrap approach on this 183-locus data set, there is no strong conflict between species trees estimated from concatenation and gene-tree-based coalescent analyses, as has been previously suggested by Gatesy and Springer (2014).

  11. Detection bias in microarray and sequencing transcriptomic analysis identified by housekeeping genes

    OpenAIRE

    Yijuan Zhang; Oluwafemi S. Akintola; Liu, Ken J.A.; Bingyun Sun

    2015-01-01

    This work includes the original data used to discover the gene ontology bias in transcriptomic analysis conducted by microarray and high throughput sequencing (Zhang et al., 2015) [1]. In the analysis, housekeeping genes were used to examine the differential detection ability by microarray and sequencing because these genes are probably the most reliably detected. The genes included here were compiled from 15 human housekeeping gene studies. The provided tables here comprise of detailed chrom...

  12. Chromosomal redistribution of male-biased genes in mammalian evolution with two bursts of gene gain on the X chromosome.

    Directory of Open Access Journals (Sweden)

    Yong E Zhang

    Full Text Available Mammalian X chromosomes evolved under various mechanisms including sexual antagonism, the faster-X process, and meiotic sex chromosome inactivation (MSCI. These forces may contribute to nonrandom chromosomal distribution of sex-biased genes. In order to understand the evolution of gene content on the X chromosome and autosome under these forces, we dated human and mouse protein-coding genes and miRNA genes on the vertebrate phylogenetic tree. We found that the X chromosome recently acquired a burst of young male-biased genes, which is consistent with fixation of recessive male-beneficial alleles by sexual antagonism. For genes originating earlier, however, this pattern diminishes and finally reverses with an overrepresentation of the oldest male-biased genes on autosomes. MSCI contributes to this dynamic since it silences X-linked old genes but not X-linked young genes. This demasculinization process seems to be associated with feminization of the X chromosome with more X-linked old genes expressed in ovaries. Moreover, we detected another burst of gene originations after the split of eutherian mammals and opossum, and these genes were quickly incorporated into transcriptional networks of multiple tissues. Preexisting X-linked genes also show significantly higher protein-level evolution during this period compared to autosomal genes, suggesting positive selection accompanied the early evolution of mammalian X chromosomes. These two findings cast new light on the evolutionary history of the mammalian X chromosome in terms of gene gain, sequence, and expressional evolution.

  13. Characterization of codon usage bias in the dUTPase gene of duck enteritis virus

    Institute of Scientific and Technical Information of China (English)

    Lichan Zhao; Anchun Cheng; Mingshu Wang; Guiping Yuan; Mingsheng Cai

    2008-01-01

    A comparative analysis of the codon usage bias in the newly discovered dUTPase gene(Assigned Accession No.:DQ4861491 of the duck enteritis virus(DEV)and the dUTPase gene of 32 reference herpesviruses was performed.The results indicated that the DEV dUT-Pase gene encodes a protein of 477 amino acids,which includes five conserved motifs with a 3-1-2-4-5 arrangement.The codon adap-tation index(CAI),effective number of codons(ENC),and GC3s values indicated synonymous codon usage bias in the dUTPase gene of herpesviruses,and this synonymous bias was correlated with host evolution.The codon usage pattens of the DEV dUTPase gene were phylogenetically conserved and similar to that of the dUTPase genes of the avian alphaherpesvirus.Although codon usage in each micro-orgamsm was different,there were no strain-specific differences among them.Sixty-one codons in the predicted polypeptide.with a strong bias towards A and T at the third codon position,were used.Comparison of the codon usage in the dUTPase gene of different organisms revealed that there were 19 codons showing distinct codon usage differences between the DEV and Escherichia coli dUTPase genes;16 between the DEV and yeast dUTPase genes;and 15 between the DEV and human dUTPase genes.Analysis of variance(ANOVA) showed significant differences between the DEV and yeast dUTPase genes(r=0.536,P<0.01).The extent of codon usage bias in the DEV dUTPase gene was highly correlated with the gene expression level,therefore the results may provide usefu information for gene classification and functional studies.

  14. Another two genes controlling mitotic intragenic recombination and recovery from UV damage in Aspergillus nidulans IV. Genetic analysis of mitotic intragenic recombinants from uvs+/uvs+, uvsD/uvsD and uvsE/uvsE diploids

    NARCIS (Netherlands)

    Fortuin, J.J.H.

    1971-01-01

    This paper presents the results of a genetic analysis of a number of spontaneous mitotic p-aminobenzoic acid-independent recombinants from uvs+/uvs+, uvsD53/uvsD53 and uvsE82/uvsE82 diploids that are heteroallelic at the pabaA locus. Intragenic recombination in each of the three strains is largely n

  15. Transcription regulation of sex-biased genes during ontogeny in the malaria vector Anopheles gambiae.

    Directory of Open Access Journals (Sweden)

    Kalle Magnusson

    Full Text Available In Anopheles gambiae, sex-regulated genes are responsible for controlling gender dimorphism and are therefore crucial in determining the ability of female mosquitoes to transmit human malaria. The identification and functional characterization of these genes will shed light on the sexual development and maturation of mosquitoes and provide useful targets for genetic control measures aimed at reducing mosquito fertility and/or distorting the sex ratio.We conducted a genome wide transcriptional analysis of sex-regulated genes from early developmental stages through adulthood combined with functional screening of novel gonadal genes. Our results demonstrate that the male-biased genes undergo a major transcription turnover starting from larval stages to adulthood. The male biased genes at the adult stage include a significant high number of unique sequences compared to the rest of the genome. This is in contrast to female-biased genes that are much more conserved and are mainly activated during late developmental stages.The high frequency of unique sequences would indicate that male-biased genes evolve more rapidly than the rest of the genome. This finding is particularly intriguing because A. gambiae is a strictly female monogamous species suggesting that driving forces in addition to sperm competition must account for the rapid evolution of male-biased genes. We have also identified and functionally characterized a number of previously unknown A. gambiae testis- and ovary-specific genes. Two of these genes, zero population growth and a suppressor of defective silencing 3 domain of the histone deacetylase co-repressor complex, were shown to play a key role in gonad development.

  16. The Code of Silence: Widespread Associations Between Synonymous Codon Biases and Gene Function.

    Science.gov (United States)

    Supek, Fran

    2016-01-01

    Some mutations in gene coding regions exchange one synonymous codon for another, and thus do not alter the amino acid sequence of the encoded protein. Even though they are often called 'silent,' these mutations may exhibit a plethora of effects on the living cell. Therefore, they are often selected during evolution, causing synonymous codon usage biases in genomes. Comparative analyses of bacterial, archaeal, fungal, and human cancer genomes have found many links between a gene's biological role and the accrual of synonymous mutations during evolution. In particular, highly expressed genes in certain functional categories are enriched with optimal codons, which are decoded by the abundant tRNAs, thus enhancing the speed and accuracy of the translating ribosome. The set of genes exhibiting codon adaptation differs between genomes, and these differences show robust associations to organismal phenotypes. In addition to selection for translation efficiency, other distinct codon bias patterns have been found in: amino acid starvation genes, cyclically expressed genes, tissue-specific genes in animals and plants, oxidative stress response genes, cellular differentiation genes, and oncogenes. In addition, genomes of organisms harboring tRNA modifications exhibit particular codon preferences. The evolutionary trace of codon bias patterns across orthologous genes may be examined to learn about a gene's relevance to various phenotypes, or, more generally, its function in the cell. PMID:26538122

  17. Codon bias and gene ontology in holometabolous and hemimetabolous insects.

    Science.gov (United States)

    Carlini, David B; Makowski, Matthew

    2015-12-01

    The relationship between preferred codon use (PCU), developmental mode, and gene ontology (GO) was investigated in a sample of nine insect species with sequenced genomes. These species were selected to represent two distinct modes of insect development, holometabolism and hemimetabolism, with an aim toward determining whether the differences in developmental timing concomitant with developmental mode would be mirrored by differences in PCU in their developmental genes. We hypothesized that the developmental genes of holometabolous insects should be under greater selective pressure for efficient translation, manifest as increased PCU, than those of hemimetabolous insects because holometabolism requires abundant protein expression over shorter time intervals than hemimetabolism, where proteins are required more uniformly in time. Preferred codon sets were defined for each species, from which the frequency of PCU for each gene was obtained. Although there were substantial differences in the genomic base composition of holometabolous and hemimetabolous insects, both groups exhibited a general preference for GC-ending codons, with the former group having higher PCU averaged across all genes. For each species, the biological process GO term for each gene was assigned that of its Drosophila homolog(s), and PCU was calculated for each GO term category. The top two GO term categories for PCU enrichment in the holometabolous insects were anatomical structure development and cell differentiation. The increased PCU in the developmental genes of holometabolous insects may reflect a general strategy to maximize the protein production of genes expressed in bursts over short time periods, e.g., heat shock proteins. J. Exp. Zool. (Mol. Dev. Evol.) 324B: 686-698, 2015. © 2015 Wiley Periodicals, Inc. PMID:26498580

  18. The SFP1 gene product of Saccharomyces cerevisiae regulates G2/M transitions during the mitotic cell cycle and DNA-damage response

    International Nuclear Information System (INIS)

    In eukaryotic cells, checkpoint pathways arrest cell-cycle progression if a particular event has failed to complete appropriately or if an important intracellular structure is defective or damaged. Saccharomyces cerevisiae strains that lack the SFP1 gene fail to arrest at the G2 DNA-damage checkpoint in response to genomic injury, but maintain their ability to arrest at the replication and spindle-assembly checkpoints. sfp1D mutants are characterized by a premature entrance into mitosis during a normal (undamaged) cell cycle, while strains that overexpress Sfp1p exhibit delays in G2. Sfp1p therefore acts as a repressor of the G2/M transition, both in the normal cell cycle and in the G2 checkpoint pathway. Sfp1 is a nuclear protein with two Cys2His2 zinc-finger domains commonly found in transcription factors. We propose that Sfp1p regulates the expression of gene products involved in the G2/M transition during the mitotic cell cycle and the DNA-damage response. In support of this model, overexpression of Sfp1p induces the expression of the PDS1 gene, which is known to encode a protein that regulates the G2 checkpoint. (author)

  19. Positional bias of general and tissue-specific regulatory motifs in mouse gene promoters

    Directory of Open Access Journals (Sweden)

    Farré Domènec

    2007-12-01

    Full Text Available Abstract Background The arrangement of regulatory motifs in gene promoters, or promoter architecture, is the result of mutation and selection processes that have operated over many millions of years. In mammals, tissue-specific transcriptional regulation is related to the presence of specific protein-interacting DNA motifs in gene promoters. However, little is known about the relative location and spacing of these motifs. To fill this gap, we have performed a systematic search for motifs that show significant bias at specific promoter locations in a large collection of housekeeping and tissue-specific genes. Results We observe that promoters driving housekeeping gene expression are enriched in particular motifs with strong positional bias, such as YY1, which are of little relevance in promoters driving tissue-specific expression. We also identify a large number of motifs that show positional bias in genes expressed in a highly tissue-specific manner. They include well-known tissue-specific motifs, such as HNF1 and HNF4 motifs in liver, kidney and small intestine, or RFX motifs in testis, as well as many potentially novel regulatory motifs. Based on this analysis, we provide predictions for 559 tissue-specific motifs in mouse gene promoters. Conclusion The study shows that motif positional bias is an important feature of mammalian proximal promoters and that it affects both general and tissue-specific motifs. Motif positional constraints define very distinct promoter architectures depending on breadth of expression and type of tissue.

  20. Biased Immunoglobulin Light Chain Gene Usage in the Shark.

    Science.gov (United States)

    Iacoangeli, Anna; Lui, Anita; Naik, Ushma; Ohta, Yuko; Flajnik, Martin; Hsu, Ellen

    2015-10-15

    This study of a large family of κ L chain clusters in nurse shark completes the characterization of its classical Ig gene content (two H chain isotypes, μ and ω, and four L chain isotypes, κ, λ, σ, and σ-2). The shark κ clusters are minigenes consisting of a simple VL-JL-CL array, where V to J recombination occurs over an ~500-bp interval, and functional clusters are widely separated by at least 100 kb. Six out of ~39 κ clusters are prerearranged in the germline (germline joined). Unlike the complex gene organization and multistep assembly process of Ig in mammals, each shark Ig rearrangement, somatic or in the germline, appears to be an independent event localized to the minigene. This study examined the expression of functional, nonproductive, and sterile transcripts of the κ clusters compared with the other three L chain isotypes. κ cluster usage was investigated in young sharks, and a skewed pattern of split gene expression was observed, one similar in functional and nonproductive rearrangements. These results show that the individual activation of the spatially distant κ clusters is nonrandom. Although both split and germline-joined κ genes are expressed, the latter are prominent in young animals and wane with age. We speculate that, in the shark, the differential activation of the multiple isotypes can be advantageously used in receptor editing.

  1. The MuvB complex sequentially recruits B-Myb and FoxM1 to promote mitotic gene expression.

    Science.gov (United States)

    Sadasivam, Subhashini; Duan, Shenghua; DeCaprio, James A

    2012-03-01

    Cell cycle progression is dependent on two major waves of gene expression. Early cell cycle gene expression occurs during G1/S to generate factors required for DNA replication, while late cell cycle gene expression begins during G2 to prepare for mitosis. Here we demonstrate that the MuvB complex-comprised of LIN9, LIN37, LIN52, LIN54, and RBBP4-serves an essential role in three distinct transcription complexes to regulate cell cycle gene expression. The MuvB complex, together with the Rb-like protein p130, E2F4, and DP1, forms the DREAM complex during quiescence and represses expression of both early and late genes. Upon cell cycle entry, the MuvB complex dissociates from p130/DREAM, binds to B-Myb, and reassociates with the promoters of late genes during S phase. MuvB and B-Myb are required for the subsequent recruitment of FoxM1 to late gene promoters during G2. The MuvB complex remains bound to FoxM1 during peak late cell cycle gene expression, while B-Myb binding is lost when it undergoes phosphorylation-dependent, proteasome-mediated degradation during late S phase. Our results reveal a novel role for the MuvB complex in recruiting B-Myb and FoxM1 to promote late cell cycle gene expression and in regulating cell cycle gene expression from quiescence through mitosis. PMID:22391450

  2. The MuvB complex sequentially recruits B-Myb and FoxM1 to promote mitotic gene expression

    Science.gov (United States)

    Sadasivam, Subhashini; Duan, Shenghua; DeCaprio, James A.

    2012-01-01

    Cell cycle progression is dependent on two major waves of gene expression. Early cell cycle gene expression occurs during G1/S to generate factors required for DNA replication, while late cell cycle gene expression begins during G2 to prepare for mitosis. Here we demonstrate that the MuvB complex—comprised of LIN9, LIN37, LIN52, LIN54, and RBBP4—serves an essential role in three distinct transcription complexes to regulate cell cycle gene expression. The MuvB complex, together with the Rb-like protein p130, E2F4, and DP1, forms the DREAM complex during quiescence and represses expression of both early and late genes. Upon cell cycle entry, the MuvB complex dissociates from p130/DREAM, binds to B-Myb, and reassociates with the promoters of late genes during S phase. MuvB and B-Myb are required for the subsequent recruitment of FoxM1 to late gene promoters during G2. The MuvB complex remains bound to FoxM1 during peak late cell cycle gene expression, while B-Myb binding is lost when it undergoes phosphorylation-dependent, proteasome-mediated degradation during late S phase. Our results reveal a novel role for the MuvB complex in recruiting B-Myb and FoxM1 to promote late cell cycle gene expression and in regulating cell cycle gene expression from quiescence through mitosis. PMID:22391450

  3. Loss of CCDC6, the first identified RET partner gene, affects pH2AX S139 levels and accelerates mitotic entry upon DNA damage.

    Directory of Open Access Journals (Sweden)

    Francesco Merolla

    Full Text Available CCDC6 was originally identified in chimeric genes caused by chromosomal translocation involving the RET proto-oncogene in some thryoid tumors mostly upon ionizing radiation exposure. Recognised as a pro-apoptotic phosphoprotein that negatively regulates CREB1-dependent transcription, CCDC6 is an ATM substrate that is responsive to genotoxic stress. Here we report that following genotoxic stress, loss or inactivation of CCDC6 in cancers that carry the CCDC6 fusion, accelerates the dephosphorylation of pH2AX S139, resulting in defective G2 arrest and premature mitotic entry. Moreover, we show that CCDC6 depleted cells appear to repair DNA damaged in a shorter time compared to controls, based on reporter assays in cells. High-troughput proteomic screening predicted the interaction between the CCDC6 gene product and the catalytic subunit of Serin-Threonin Protein Phosphatase 4 (PP4c recently identified as the evolutionarily conserved pH2AX S139 phosphatase that is activated upon DNA Damage. We describe the interaction between CCDC6 and PP4c and we report the modulation of PP4c enzymatic activity in CCDC6 depleted cells. We discuss the functional significance of CCDC6-PP4c interactions and hypothesize that CCDC6 may act in the DNA Damage Response by negatively modulating PP4c activity. Overall, our data suggest that in primary tumours the loss of CCDC6 function could influence genome stability and thereby contribute to carcinogenesis.

  4. The MuvB complex sequentially recruits B-Myb and FoxM1 to promote mitotic gene expression

    OpenAIRE

    Sadasivam, Subhashini; Duan, Shenghua; DeCaprio, James A.

    2012-01-01

    Gene expression is tightly regulated during cell cycle progression. DeCaprio and colleagues now provide a comprehensive model of the MuvB complex's dynamic control of cell cycle gene expression from quiescence through mitosis. They find that MuvB sequentially recruits B-Myb and then FoxM1 to gene promoters during G2/M. The study provides a definitive description of MuvB's central role as a part of three distinct transcription complexes in the coordinated expression of a large number of genes ...

  5. Biased distribution of DNA uptake sequences towards genome maintenance genes

    DEFF Research Database (Denmark)

    Davidsen, T.; Rodland, E.A.; Lagesen, K.;

    2004-01-01

    Repeated sequence signatures are characteristic features of all genomic DNA. We have made a rigorous search for repeat genomic sequences in the human pathogens Neisseria meningitidis, Neisseria gonorrhoeae and Haemophilus influenzae and found that by far the most frequent 9-10mers residing within...... in these organisms. Pasteurella multocida also displayed high frequencies of a putative DUS identical to that previously identified in H. influenzae and with a skewed distribution towards genome maintenance genes, indicating that this bacterium might be transformation competent under certain conditions....

  6. Gene network and pathway analysis of mice with conditional ablation of Dicer in post-mitotic neurons.

    Directory of Open Access Journals (Sweden)

    Véronique Dorval

    Full Text Available BACKGROUND: The small non-protein-coding microRNAs (miRNAs have emerged as critical regulators of neuronal differentiation, identity and survival. To date, however, little is known about the genes and molecular networks regulated by neuronal miRNAs in vivo, particularly in the adult mammalian brain. METHODOLOGY/PRINCIPAL FINDINGS: We analyzed whole genome microarrays from mice lacking Dicer, the enzyme responsible for miRNA production, specifically in postnatal forebrain neurons. A total of 755 mRNA transcripts were significantly (P<0.05, FDR<0.25 misregulated in the conditional Dicer knockout mice. Ten genes, including Tnrc6c, Dnmt3a, and Limk1, were validated by real time quantitative RT-PCR. Upregulated transcripts were enriched in nonneuronal genes, which is consistent with previous studies in vitro. Microarray data mining showed that upregulated genes were enriched in biological processes related to gene expression regulation, while downregulated genes were associated with neuronal functions. Molecular pathways associated with neurological disorders, cellular organization and cellular maintenance were altered in the Dicer mutant mice. Numerous miRNA target sites were enriched in the 3'untranslated region (3'UTR of upregulated genes, the most significant corresponding to the miR-124 seed sequence. Interestingly, our results suggest that, in addition to miR-124, a large fraction of the neuronal miRNome participates, by order of abundance, in coordinated gene expression regulation and neuronal maintenance. CONCLUSIONS/SIGNIFICANCE: Taken together, these results provide new clues into the role of specific miRNA pathways in the regulation of brain identity and maintenance in adult mice.

  7. Oxytocin receptor gene and racial ingroup bias in empathy-related brain activity.

    Science.gov (United States)

    Luo, Siyang; Li, Bingfeng; Ma, Yina; Zhang, Wenxia; Rao, Yi; Han, Shihui

    2015-04-15

    The human brain responds more strongly to racial ingroup than outgroup individuals' pain. This racial ingroup bias varies across individuals and has been attributed to social experiences. What remains unknown is whether the racial ingroup bias in brain activity is associated with a genetic polymorphism. We investigated genetic associations of racial ingroup bias in the brain activity to racial ingroup and outgroup faces that received painful or non-painful stimulations by scanning A/A and G/G homozygous of the oxytocin receptor gene polymorphism (OXTR rs53576) using functional MRI. We found that G/G compared to A/A individuals showed stronger activity in the anterior cingulate and supplementary motor area (ACC/SMA) in response to racial ingroup members' pain, whereas A/A relative to G/G individuals exhibited greater activity in the nucleus accumbens (NAcc) in response to racial outgroup members' pain. Moreover, the racial ingroup bias in ACC/SMA activity positively predicted participants' racial ingroup bias in implicit attitudes and NAcc activity to racial outgroup individuals' pain negatively predicted participants' motivations to reduce racial outgroup members' pain. Our results suggest that the two variants of OXTR rs53576 are associated with racial ingroup bias in brain activities that are linked to implicit attitude and altruistic motivation, respectively. PMID:25637390

  8. Sex-biased gene expression in dioecious garden asparagus (Asparagus officinalis).

    Science.gov (United States)

    Harkess, Alex; Mercati, Francesco; Shan, Hong-Yan; Sunseri, Francesco; Falavigna, Agostino; Leebens-Mack, Jim

    2015-08-01

    Sex chromosomes have evolved independently in phylogenetically diverse flowering plant lineages. The genes governing sex determination in dioecious species remain unknown, but theory predicts that the linkage of genes influencing male and female function will spur the origin and early evolution of sex chromosomes. For example, in an XY system, the origin of an active Y may be spurred by the linkage of female suppressing and male promoting genes. Garden asparagus (Asparagus officinalis) serves as a model for plant sex chromosome evolution, given that it has recently evolved an XX/XY sex chromosome system. In order to elucidate the molecular basis of gender differences and sex determination, we used RNA-sequencing (RNA-Seq) to identify differentially expressed genes between female (XX), male (XY) and supermale (YY) individuals. We identified 570 differentially expressed genes, and showed that significantly more genes exhibited male-biased than female-biased expression in garden asparagus. In the context of anther development, we identified genes involved in pollen microspore and tapetum development that were specifically expressed in males and supermales. Comparative analysis of genes in the Arabidopsis thaliana, Zea mays and Oryza sativa anther development pathways shows that anther sterility in females probably occurs through interruption of tapetum development before microspore meiosis.

  9. Sex-biased gene expression in dioecious garden asparagus (Asparagus officinalis).

    Science.gov (United States)

    Harkess, Alex; Mercati, Francesco; Shan, Hong-Yan; Sunseri, Francesco; Falavigna, Agostino; Leebens-Mack, Jim

    2015-08-01

    Sex chromosomes have evolved independently in phylogenetically diverse flowering plant lineages. The genes governing sex determination in dioecious species remain unknown, but theory predicts that the linkage of genes influencing male and female function will spur the origin and early evolution of sex chromosomes. For example, in an XY system, the origin of an active Y may be spurred by the linkage of female suppressing and male promoting genes. Garden asparagus (Asparagus officinalis) serves as a model for plant sex chromosome evolution, given that it has recently evolved an XX/XY sex chromosome system. In order to elucidate the molecular basis of gender differences and sex determination, we used RNA-sequencing (RNA-Seq) to identify differentially expressed genes between female (XX), male (XY) and supermale (YY) individuals. We identified 570 differentially expressed genes, and showed that significantly more genes exhibited male-biased than female-biased expression in garden asparagus. In the context of anther development, we identified genes involved in pollen microspore and tapetum development that were specifically expressed in males and supermales. Comparative analysis of genes in the Arabidopsis thaliana, Zea mays and Oryza sativa anther development pathways shows that anther sterility in females probably occurs through interruption of tapetum development before microspore meiosis. PMID:25817071

  10. 8p22 MTUS1 gene product ATIP3 is a novel anti-mitotic protein underexpressed in invasive breast carcinoma of poor prognosis.

    Directory of Open Access Journals (Sweden)

    Sylvie Rodrigues-Ferreira

    Full Text Available BACKGROUND: Breast cancer is a heterogeneous disease that is not totally eradicated by current therapies. The classification of breast tumors into distinct molecular subtypes by gene profiling and immunodetection of surrogate markers has proven useful for tumor prognosis and prediction of effective targeted treatments. The challenge now is to identify molecular biomarkers that may be of functional relevance for personalized therapy of breast tumors with poor outcome that do not respond to available treatments. The Mitochondrial Tumor Suppressor (MTUS1 gene is an interesting candidate whose expression is reduced in colon, pancreas, ovary and oral cancers. The present study investigates the expression and functional effects of MTUS1 gene products in breast cancer. METHODS AND FINDINGS: By means of gene array analysis, real-time RT-PCR and immunohistochemistry, we show here that MTUS1/ATIP3 is significantly down-regulated in a series of 151 infiltrating breast cancer carcinomas as compared to normal breast tissue. Low levels of ATIP3 correlate with high grade of the tumor and the occurrence of distant metastasis. ATIP3 levels are also significantly reduced in triple negative (ER- PR- HER2- breast carcinomas, a subgroup of highly proliferative tumors with poor outcome and no available targeted therapy. Functional studies indicate that silencing ATIP3 expression by siRNA increases breast cancer cell proliferation. Conversely, restoring endogenous levels of ATIP3 expression leads to reduced cancer cell proliferation, clonogenicity, anchorage-independent growth, and reduces the incidence and size of xenografts grown in vivo. We provide evidence that ATIP3 associates with the microtubule cytoskeleton and localizes at the centrosomes, mitotic spindle and intercellular bridge during cell division. Accordingly, live cell imaging indicates that ATIP3 expression alters the progression of cell division by promoting prolonged metaphase, thereby leading to a

  11. Accelerated rates of protein evolution in barley grain and pistil biased genes might be legacy of domestication.

    Science.gov (United States)

    Shi, Tao; Dimitrov, Ivan; Zhang, Yinling; Tax, Frans E; Yi, Jing; Gou, Xiaoping; Li, Jia

    2015-10-01

    Traits related to grain and reproductive organs in grass crops have been under continuous directional selection during domestication. Barley is one of the oldest domesticated crops in human history. Thus genes associated with the grain and reproductive organs in barley may show evidence of dramatic evolutionary change. To understand how artificial selection contributes to protein evolution of biased genes in different barley organs, we used Digital Gene Expression analysis of six barley organs (grain, pistil, anther, leaf, stem and root) to identify genes with biased expression in specific organs. Pairwise comparisons of orthologs between barley and Brachypodium distachyon, as well as between highland and lowland barley cultivars mutually indicated that grain and pistil biased genes show relatively higher protein evolutionary rates compared with the median of all orthologs and other organ biased genes. Lineage-specific protein evolutionary rates estimation showed similar patterns with elevated protein evolution in barley grain and pistil biased genes, yet protein sequences generally evolve much faster in the lowland barley cultivar. Further functional annotations revealed that some of these grain and pistil biased genes with rapid protein evolution are related to nutrient biosynthesis and cell cycle/division. Our analyses provide insights into how domestication differentially shaped the evolution of genes specific to different organs of a crop species, and implications for future functional studies of domestication genes.

  12. The impact of selection, gene conversion, and biased sampling on the assessment of microbial demography

    OpenAIRE

    Lapierre, Marguerite; Blin, Camille; Lambert, Amaury; Achaz, Guillaume; Eduardo P C Rocha

    2016-01-01

    International audience Recent studies have linked demographic changes and epidemiological patterns in bacterial populations using coalescent-based approaches. We identified 26 studies using skyline plots and found that 21 inferred overall population expansion. This surprising result led us to analyze the impact of natural selection, recombination (gene conversion), and sampling biases on demographic inference using skyline plots and site frequency spectra (SFS). Forward simulations based o...

  13. Bacterial mitotic machineries

    DEFF Research Database (Denmark)

    Gerdes, Kenn; Møller-Jensen, Jakob; Ebersbach, Gitte;

    2004-01-01

    Here, we review recent progress that yields fundamental new insight into the molecular mechanisms behind plasmid and chromosome segregation in prokaryotic cells. In particular, we describe how prokaryotic actin homologs form mitotic machineries that segregate DNA before cell division. Thus, the P...

  14. Mitotic spindle perturbations

    NARCIS (Netherlands)

    Tame, Mihoko Amy

    2016-01-01

    Microtubules are major components of the cytoskeleton and form the bipolar spindle apparatus during mitosis. The mitotic spindle consists of highly dynamic microtubule polymers that are under constant modulation, controlled by multiple motor proteins and microtubule-associated proteins. This tight s

  15. Bacterial mitotic machineries

    DEFF Research Database (Denmark)

    Gerdes, Kenn; Møller-Jensen, Jakob; Ebersbach, Gitte;

    2004-01-01

    Here, we review recent progress that yields fundamental new insight into the molecular mechanisms behind plasmid and chromosome segregation in prokaryotic cells. In particular, we describe how prokaryotic actin homologs form mitotic machineries that segregate DNA before cell division. Thus, the Par...

  16. Untangling the Contributions of Sex-Specific Gene Regulation and X-Chromosome Dosage to Sex-Biased Gene Expression in Caenorhabditis elegans.

    Science.gov (United States)

    Kramer, Maxwell; Rao, Prashant; Ercan, Sevinc

    2016-09-01

    Dosage compensation mechanisms equalize the level of X chromosome expression between sexes. Yet the X chromosome is often enriched for genes exhibiting sex-biased, i.e., imbalanced expression. The relationship between X chromosome dosage compensation and sex-biased gene expression remains largely unexplored. Most studies determine sex-biased gene expression without distinguishing between contributions from X chromosome copy number (dose) and the animal's sex. Here, we uncoupled X chromosome dose from sex-specific gene regulation in Caenorhabditis elegans to determine the effect of each on X expression. In early embryogenesis, when dosage compensation is not yet fully active, X chromosome dose drives the hermaphrodite-biased expression of many X-linked genes, including several genes that were shown to be responsible for hermaphrodite fate. A similar effect is seen in the C. elegans germline, where X chromosome dose contributes to higher hermaphrodite X expression, suggesting that lack of dosage compensation in the germline may have a role in supporting higher expression of X chromosomal genes with female-biased functions in the gonad. In the soma, dosage compensation effectively balances X expression between the sexes. As a result, somatic sex-biased expression is almost entirely due to sex-specific gene regulation. These results suggest that lack of dosage compensation in different tissues and developmental stages allow X chromosome copy number to contribute to sex-biased gene expression and function.

  17. Transfer RNA gene numbers may not be completely responsible for the codon usage bias in asparagine, isoleucine, phenylalanine, and tyrosine in the high expression genes in bacteria.

    Science.gov (United States)

    Satapathy, Siddhartha Sankar; Dutta, Malay; Buragohain, Alak Kumar; Ray, Suvendra Kumar

    2012-08-01

    It is generally believed that the effect of translational selection on codon usage bias is related to the number of transfer RNA genes in bacteria, which is more with respect to the high expression genes than the whole genome. Keeping this in the background, we analyzed codon usage bias with respect to asparagine, isoleucine, phenylalanine, and tyrosine amino acids. Analysis was done in seventeen bacteria with the available gene expression data and information about the tRNA gene number. In most of the bacteria, it was observed that codon usage bias and tRNA gene number were not in agreement, which was unexpected. We extended the study further to 199 bacteria, limiting to the codon usage bias in the two highly expressed genes rpoB and rpoC which encode the RNA polymerase subunits β and β', respectively. In concordance with the result in the high expression genes, codon usage bias in rpoB and rpoC genes was also found to not be in agreement with tRNA gene number in many of these bacteria. Our study indicates that tRNA gene numbers may not be the sole determining factor for translational selection of codon usage bias in bacterial genomes.

  18. Mitotic chromosome condensation in vertebrates

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-07-15

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

  19. Is GC bias in the nuclear genome of the carnivorous plant Utricularia driven by ROS-based mutation and biased gene conversion?

    Science.gov (United States)

    Ibarra-Laclette, Enrique; Albert, Victor A; Herrera-Estrella, Alfredo; Herrera-Estrella, Luis

    2011-11-01

    At less than 90 Mbp, the tiny nuclear genome of the carnivorous bladderwort plant Utricularia is an attractive model system for studying molecular evolutionary processes leading to genome miniaturization. Recently, we reported that expression of genes encoding DNA repair and reactive oxygen species (ROS) detoxification enzymes is highest in Utricularia traps, and we argued that ROS mutagenic action correlates with the high nucleotide substitution rates observed in the Utricularia plastid, mitochondrial, and nuclear genomes. Here, we extend our analysis of 100 nuclear genes from Utricularia and related asterid eudicots to examine nucleotide substitution biases and their potential correlation with ROS-induced DNA lesions. We discovered an unusual bias toward GC nucleotides, most prominently in transition substitutions at the third position of codons, which are presumably silent with respect to adaptation. Given the general tendency of biased gene conversion to drive GC bias, and of ROS to induce double strand breaks requiring recombinational repair, we propose that some of the unusual features of the bladderwort and its genome may be more reflective of these nonadaptive processes than of natural selection. PMID:22057327

  20. Tissue Specificity and Sex-Specific Regulatory Variation Permit the Evolution of Sex-Biased Gene Expression.

    Science.gov (United States)

    Dean, Rebecca; Mank, Judith E

    2016-09-01

    Genetic correlations between males and females are often thought to constrain the evolution of sexual dimorphism. However, sexually dimorphic traits and the underlying sexually dimorphic gene expression patterns are often rapidly evolving. We explore this apparent paradox by measuring the genetic correlation in gene expression between males and females (Cmf) across broad evolutionary timescales, using two RNA-sequencing data sets spanning multiple populations and multiple species. We find that unbiased genes have higher Cmf than sex-biased genes, consistent with intersexual genetic correlations constraining the evolution of sexual dimorphism. However, we found that highly sex-biased genes (both male and female biased) also had higher tissue specificity, and unbiased genes had greater expression breadth, suggesting that pleiotropy may constrain the breakdown of intersexual genetic correlations. Finally, we show that genes with high Cmf showed some degree of sex-specific changes in gene expression in males and females. Together, our results suggest that genetic correlations between males and females may be less important in constraining the evolution of sex-biased gene expression than pleiotropy. Sex-specific regulatory variation and tissue specificity may resolve the paradox of widespread sex bias within a largely shared genome.

  1. Biased gene fractionation and dominant gene expression among the subgenomes of Brassica rapa.

    Directory of Open Access Journals (Sweden)

    Feng Cheng

    Full Text Available Polyploidization, both ancient and recent, is frequent among plants. A "two-step theory" was proposed to explain the meso-triplication of the Brassica "A" genome: Brassica rapa. By accurately partitioning of this genome, we observed that genes in the less fractioned subgenome (LF were dominantly expressed over the genes in more fractioned subgenomes (MFs: MF1 and MF2, while the genes in MF1 were slightly dominantly expressed over the genes in MF2. The results indicated that the dominantly expressed genes tended to be resistant against gene fractionation. By re-sequencing two B. rapa accessions: a vegetable turnip (VT117 and a Rapid Cycling line (L144, we found that genes in LF had less non-synonymous or frameshift mutations than genes in MFs; however mutation rates were not significantly different between MF1 and MF2. The differences in gene expression patterns and on-going gene death among the three subgenomes suggest that "two-step" genome triplication and differential subgenome methylation played important roles in the genome evolution of B. rapa.

  2. An improved, bias-reduced probabilistic functional gene network of baker's yeast, Saccharomyces cerevisiae.

    Directory of Open Access Journals (Sweden)

    Insuk Lee

    Full Text Available BACKGROUND: Probabilistic functional gene networks are powerful theoretical frameworks for integrating heterogeneous functional genomics and proteomics data into objective models of cellular systems. Such networks provide syntheses of millions of discrete experimental observations, spanning DNA microarray experiments, physical protein interactions, genetic interactions, and comparative genomics; the resulting networks can then be easily applied to generate testable hypotheses regarding specific gene functions and associations. METHODOLOGY/PRINCIPAL FINDINGS: We report a significantly improved version (v. 2 of a probabilistic functional gene network of the baker's yeast, Saccharomyces cerevisiae. We describe our optimization methods and illustrate their effects in three major areas: the reduction of functional bias in network training reference sets, the application of a probabilistic model for calculating confidences in pair-wise protein physical or genetic interactions, and the introduction of simple thresholds that eliminate many false positive mRNA co-expression relationships. Using the network, we predict and experimentally verify the function of the yeast RNA binding protein Puf6 in 60S ribosomal subunit biogenesis. CONCLUSIONS/SIGNIFICANCE: YeastNet v. 2, constructed using these optimizations together with additional data, shows significant reduction in bias and improvements in precision and recall, in total covering 102,803 linkages among 5,483 yeast proteins (95% of the validated proteome. YeastNet is available from http://www.yeastnet.org.

  3. Biased exonization of transposed elements in duplicated genes: A lesson from the TIF-IA gene

    Directory of Open Access Journals (Sweden)

    Shomron Noam

    2007-11-01

    Full Text Available Abstract Background Gene duplication and exonization of intronic transposed elements are two mechanisms that enhance genomic diversity. We examined whether there is less selection against exonization of transposed elements in duplicated genes than in single-copy genes. Results Genome-wide analysis of exonization of transposed elements revealed a higher rate of exonization within duplicated genes relative to single-copy genes. The gene for TIF-IA, an RNA polymerase I transcription initiation factor, underwent a humanoid-specific triplication, all three copies of the gene are active transcriptionally, although only one copy retains the ability to generate the TIF-IA protein. Prior to TIF-IA triplication, an Alu element was inserted into the first intron. In one of the non-protein coding copies, this Alu is exonized. We identified a single point mutation leading to exonization in one of the gene duplicates. When this mutation was introduced into the TIF-IA coding copy, exonization was activated and the level of the protein-coding mRNA was reduced substantially. A very low level of exonization was detected in normal human cells. However, this exonization was abundant in most leukemia cell lines evaluated, although the genomic sequence is unchanged in these cancerous cells compared to normal cells. Conclusion The definition of the Alu element within the TIF-IA gene as an exon is restricted to certain types of cancers; the element is not exonized in normal human cells. These results further our understanding of the delicate interplay between gene duplication and alternative splicing and of the molecular evolutionary mechanisms leading to genetic innovations. This implies the existence of purifying selection against exonization in single copy genes, with duplicate genes free from such constrains.

  4. The relationship between third-codon position nucleotide content, codon bias, mRNA secondary structure and gene expression in the drosophilid alcohol dehydrogenase genes Adh and Adhr.

    Science.gov (United States)

    Carlini, D B; Chen, Y; Stephan, W

    2001-01-01

    To gain insights into the relationship between codon bias, mRNA secondary structure, third-codon position nucleotide distribution, and gene expression, we predicted secondary structures in two related drosophilid genes, Adh and Adhr, which differ in degree of codon bias and level of gene expression. Individual structural elements (helices) were inferred using the comparative method. For each gene, four types of randomization simulations were performed to maintain/remove codon bias and/or to maintain or alter third-codon position nucleotide composition (N3). In the weakly expressed, weakly biased gene Adhr, the potential for secondary structure formation was found to be much stronger than in the highly expressed, highly biased gene Adh. This is consistent with the observation of approximately equal G and C percentages in Adhr ( approximately 31% across species), whereas in Adh the N3 distribution is shifted toward C (42% across species). Perturbing the N3 distribution to approximately equal amounts of A, G, C, and T increases the potential for secondary structure formation in Adh, but decreases it in Adhr. On the other hand, simulations that reduce codon bias without changing N3 content indicate that codon bias per se has only a weak effect on the formation of secondary structures. These results suggest that, for these two drosophilid genes, secondary structure is a relatively independent, negative regulator of gene expression. Whereas the degree of codon bias is positively correlated with level of gene expression, strong individual secondary structural elements may be selected for to retard mRNA translation and to decrease gene expression. PMID:11606539

  5. Biased Gene Fractionation and Dominant Gene Expression among the Subgenomes of Brassica rapa

    OpenAIRE

    Feng Cheng; Jian Wu; Lu Fang; Silong Sun; Bo Liu; Ke Lin; Guusje Bonnema; Xiaowu Wang

    2012-01-01

    Polyploidization, both ancient and recent, is frequent among plants. A ‘‘two-step theory’’ was proposed to explain the meso-triplication of the Brassica ‘‘A’’ genome: Brassica rapa. By accurately partitioning of this genome, we observed that genes in the less fractioned subgenome (LF) were dominantly expressed over the genes in more fractioned subgenomes (MFs: MF1 and MF2), while the genes in MF1 were slightly dominantly expressed over the genes in MF2. The results indicated that the dominant...

  6. Common sources of bias in gene-lifestyle interaction studies of cardiometabolic disease

    DEFF Research Database (Denmark)

    Oskari Kilpeläinen, Tuomas

    2013-01-01

    The role of gene x lifestyle interactions in the development of cardiometabolic diseases is often highlighted, but very few robustly replicated examples of interactions exist in the literature. The slow pace of discoveries may largely be due to interaction effects being generally small in magnitude...... and/or more complex than initially thought. However, the progress may also be hindered by the poor accuracy in large-scale epidemiological studies to estimate the true interaction effect sizes. Often, this bias tends to underestimate the interaction effect, leading to inadequate statistical power...

  7. Exploring codon context bias for synthetic gene design of a thermostable invertase in Escherichia coli.

    Science.gov (United States)

    Pek, Han Bin; Klement, Maximilian; Ang, Kok Siong; Chung, Bevan Kai-Sheng; Ow, Dave Siak-Wei; Lee, Dong-Yup

    2015-01-01

    Various isoforms of invertases from prokaryotes, fungi, and higher plants has been expressed in Escherichia coli, and codon optimisation is a widely-adopted strategy for improvement of heterologous enzyme expression. Successful synthetic gene design for recombinant protein expression can be done by matching its translational elongation rate against heterologous host organisms via codon optimization. Amongst the various design parameters considered for the gene synthesis, codon context bias has been relatively overlooked compared to individual codon usage which is commonly adopted in most of codon optimization tools. In addition, matching the rates of transcription and translation based on secondary structure may lead to enhanced protein folding. In this study, we evaluated codon context fitness as design criterion for improving the expression of thermostable invertase from Thermotoga maritima in Escherichia coli and explored the relevance of secondary structure regions for folding and expression. We designed three coding sequences by using (1) a commercial vendor optimized gene algorithm, (2) codon context for the whole gene, and (3) codon context based on the secondary structure regions. Then, the codon optimized sequences were transformed and expressed in E. coli. From the resultant enzyme activities and protein yield data, codon context fitness proved to have the highest activity as compared to the wild-type control and other criteria while secondary structure-based strategy is comparable to the control. Codon context bias was shown to be a relevant parameter for enhancing enzyme production in Escherichia coli by codon optimization. Thus, we can effectively design synthetic genes within heterologous host organisms using this criterion. PMID:26047917

  8. Genome-wide analysis reveals diverged patterns of codon bias, gene expression, and rates of sequence evolution in Picea gene families

    OpenAIRE

    De La Torre, Amanda R; Lin, Yao-Cheng; van de Peer, Yves; Pär K Ingvarsson

    2015-01-01

    The recent sequencing of several gymnosperm genomes has greatly facilitated studying the evolution of their genes and gene families. In this study, we examine the evidence for expression-mediated selection in the first two fully sequenced representatives of the gymnosperm plant clade (Picea abies and Picea glauca). We use genome-wide estimates of gene expression (> 50,000 expressed genes) to study the relationship between gene expression, codon bias, rates of sequence divergence, protein l...

  9. Genetic clusters and sex-biased gene flow in a unicolonial Formica ant

    Directory of Open Access Journals (Sweden)

    Chapuisat Michel

    2009-03-01

    Full Text Available Abstract Background Animal societies are diverse, ranging from small family-based groups to extraordinarily large social networks in which many unrelated individuals interact. At the extreme of this continuum, some ant species form unicolonial populations in which workers and queens can move among multiple interconnected nests without eliciting aggression. Although unicoloniality has been mostly studied in invasive ants, it also occurs in some native non-invasive species. Unicoloniality is commonly associated with very high queen number, which may result in levels of relatedness among nestmates being so low as to raise the question of the maintenance of altruism by kin selection in such systems. However, the actual relatedness among cooperating individuals critically depends on effective dispersal and the ensuing pattern of genetic structuring. In order to better understand the evolution of unicoloniality in native non-invasive ants, we investigated the fine-scale population genetic structure and gene flow in three unicolonial populations of the wood ant F. paralugubris. Results The analysis of geo-referenced microsatellite genotypes and mitochondrial haplotypes revealed the presence of cryptic clusters of genetically-differentiated nests in the three populations of F. paralugubris. Because of this spatial genetic heterogeneity, members of the same clusters were moderately but significantly related. The comparison of nuclear (microsatellite and mitochondrial differentiation indicated that effective gene flow was male-biased in all populations. Conclusion The three unicolonial populations exhibited male-biased and mostly local gene flow. The high number of queens per nest, exchanges among neighbouring nests and restricted long-distance gene flow resulted in large clusters of genetically similar nests. The positive relatedness among clustermates suggests that kin selection may still contribute to the maintenance of altruism in unicolonial

  10. Expression of the Saccharomyces cerevisiae DNA repair gene RAD6 that encodes a ubiquitin conjugating enzyme, increases in response to DNA damage and in meiosis but remains constant during the mitotic cell cycle.

    Science.gov (United States)

    Madura, K; Prakash, S; Prakash, L

    1990-02-25

    The RAD6 gene of Saccharomyces cerevisiae encodes a ubiquitin-conjugating (E2) enzyme and is required for the repair of damaged DNA, mutagenesis, and sporulation. Here, we report our studies on the regulation of RAD6 gene expression after UV damage, during the mitotic cell cycle, in meiosis, and following heat shock and starvation. RAD6 mRNA levels became elevated in cells exposed to UV light, and at all UV doses the increase in mRNA levels was rapid and occurred within 30 min after exposure to UV. RAD6 mRNA levels also increased in sporulating MATa/MAT alpha cells, and the period of maximal accumulation of RAD6 mRNA during meiosis is coincident with the time during which recombination occurs. However, RAD6 mRNA levels showed no periodic fluctuation in the mitotic cell cycle, were not elevated upon heat shock, and fell in cells in the stationary phase of growth. These observations suggest that RAD6 activity is required throughout the cell cycle rather than being restricted to a specific stage, and that during meiosis, high levels of RAD6 activity may be needed at a stage coincident with genetic recombination. The observation that RAD6 transcription is not induced by heat and starvation, treatments that activate stress responses, suggests that the primary role of RAD6 is in the repair of damaged DNA rather than in adapting cells to stress situations.

  11. Is there a close relationship between synonymous codon bias and codon-anticodon binding strength in human genes?

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Synonymous codon bias has been examined in 78 human genes (19967 codons) and measured by relative synonymous codon usage (RSCU). Relative frequencies of all kinds of dinucleotides in 2,3 or 3,4 codon positions have been calculated, and codon-anticodon binding strength has been estimated by the stacking energies of codon-anticodon bases in Watson-Crick pairs. The data show common features in synonymous codon bias for all codon families in human genes: all C-ending codons, which possess the strongest co-don-anticodon binding energies, are the most favored codons in almost all codon families, and those codons with medium codon-anticodon binding energies are avoided. Data analysis suggests that besides isochore and genome signature , codon-anticodon binding strength may be closely related to syn-onymous codon choice in human genes. The join-effect of these factors on human genes results in the common features in codon bias.

  12. Biased perception about gene technology: How perceived naturalness and affect distort benefit perception.

    Science.gov (United States)

    Siegrist, Michael; Hartmann, Christina; Sütterlin, Bernadette

    2016-01-01

    In two experiments, the participants showed biased responses when asked to evaluate the benefits of gene technology. They evaluated the importance of additional yields in corn fields due to a newly introduced variety, which would increase a farmer's revenues. In one condition, the newly introduced variety was described as a product of traditional breeding; in the other, it was identified as genetically modified (GM). The two experiments' findings showed that the same benefits were perceived as less important for a farmer when these were the result of GM crops compared with traditionally bred crops. Mediation analyses suggest that perceived naturalness and the affect associated with the technology per se influence the interpretation of the new information. The lack of perceived naturalness of gene technology seems to be the reason for the participants' perceived lower benefits of a new corn variety in the gene technology condition compared with the perceptions of the participants assigned to the traditional breeding condition. The strategy to increase the acceptance of gene technology by introducing plant varieties that better address consumer and producer needs may not work because people discount its associated benefits. PMID:26505287

  13. Biased Gene Fractionation and Dominant Gene Expression among the Subgenomes of Brassica rapa

    NARCIS (Netherlands)

    Cheng, F.; Wu, J.; Fang, L.; Sun, S.; Liu, B.; Lin, K.; Bonnema, A.B.; Wang, Xiaowu

    2012-01-01

    Polyploidization, both ancient and recent, is frequent among plants. A ‘‘two-step theory’’ was proposed to explain the meso-triplication of the Brassica ‘‘A’’ genome: Brassica rapa. By accurately partitioning of this genome, we observed that genes in the less fractioned subgenome (LF) were dominantl

  14. Expression profiling of 519 kinase genes in matched malignant peripheral nerve sheath tumor/plexiform neurofibroma samples is discriminatory and identifies mitotic regulators BUB1B, PBK and NEK2 as overexpressed with transformation.

    Science.gov (United States)

    Stricker, Thomas P; Henriksen, Kammi J; Tonsgard, James H; Montag, Anthony G; Krausz, Thomas N; Pytel, Peter

    2013-07-01

    About 50% of all malignant peripheral nerve sheath tumors (MPNSTs) arise as neurofibromatosis type 1 associated lesions. In those patients malignant peripheral nerve sheath tumors are thought to arise through malignant transformation of a preexisting plexiform neurofibroma. The molecular changes associated with this transformation are still poorly understood. We sought to test the hypothesis that dysregulation of expression of kinases contributes to this malignant transformation. We analyzed expression of all 519 kinase genes in the human genome using the nanostring nCounter system. Twelve cases of malignant peripheral nerve sheath tumor arising in a background of preexisting plexiform neurofibroma were included. Both components were separately sampled. Statistical analysis compared global changes in expression levels as well as changes observed in the pairwise comparison of samples taken from the same surgical specimen. Immunohistochemical studies were performed on tissue array slides to confirm expression of selected proteins. The expression pattern of kinase genes can separate malignant peripheral nerve sheath tumors and preexisting plexiform neurofibromas. The majority of kinase genes is downregulated rather than overexpressed with malignant transformation. The patterns of expression changes are complex without simple recurring alteration. Pathway analysis demonstrates that differentially expressed kinases are enriched for kinases involved in the direct regulation of mitosis, and several of these show increased expression in malignant peripheral nerve sheath tumors. Immunohistochemical studies for the mitotic regulators BUB1B, PBK and NEK2 confirm higher expression levels at the protein level. These results suggest that the malignant transformation of plexiform neurofibroma is associated with distinct changes in the expression of kinase genes. The patterns of these changes are complex and heterogeneous. There is no single unifying alteration. Kinases involved

  15. Molecular mechanisms of DNA recombination: testing mitotic and meiotic models

    International Nuclear Information System (INIS)

    A hyperhaploid n + 1 strain of Saccharomyces cerevisiae (LBL1) disomic for chromosome VII was employed to isolate hyper-rec and hypo-rec mutations affecting spontaneous mitotic gene conversion and intergenic recombination. The genotype of LBL1 permits simultaneous and independent identification of rec mutations that enhance or diminish gene conversion and those that enhance or diminish intergenic recombination. Five phenotypic groups of rec mutants were isolated following ultraviolet light mutagenesis. Rec mutations that simultaneously abolish or enhance both classes of recombinational events were detected. These results demonstrate that gene conversion and intergenic recombination are under joint genetic control in mitotic cells. Conversion-specific and intergenic recombination-specific rec mutants were also recovered. Their properties indicate that conversion and intergenic recombination are separable pheonomena dependent upon discrete REC genes. The rec mutants isolated in LBL1 provide a method to test molecular models of mitotic and meiotic recombination

  16. Brown and polar bear Y chromosomes reveal extensive male-biased gene flow within brother lineages.

    Science.gov (United States)

    Bidon, Tobias; Janke, Axel; Fain, Steven R; Eiken, Hans Geir; Hagen, Snorre B; Saarma, Urmas; Hallström, Björn M; Lecomte, Nicolas; Hailer, Frank

    2014-06-01

    Brown and polar bears have become prominent examples in phylogeography, but previous phylogeographic studies relied largely on maternally inherited mitochondrial DNA (mtDNA) or were geographically restricted. The male-specific Y chromosome, a natural counterpart to mtDNA, has remained underexplored. Although this paternally inherited chromosome is indispensable for comprehensive analyses of phylogeographic patterns, technical difficulties and low variability have hampered its application in most mammals. We developed 13 novel Y-chromosomal sequence and microsatellite markers from the polar bear genome and screened these in a broad geographic sample of 130 brown and polar bears. We also analyzed a 390-kb-long Y-chromosomal scaffold using sequencing data from published male ursine genomes. Y chromosome evidence support the emerging understanding that brown and polar bears started to diverge no later than the Middle Pleistocene. Contrary to mtDNA patterns, we found 1) brown and polar bears to be reciprocally monophyletic sister (or rather brother) lineages, without signals of introgression, 2) male-biased gene flow across continents and on phylogeographic time scales, and 3) male dispersal that links the Alaskan ABC islands population to mainland brown bears. Due to female philopatry, mtDNA provides a highly structured estimate of population differentiation, while male-biased gene flow is a homogenizing force for nuclear genetic variation. Our findings highlight the importance of analyzing both maternally and paternally inherited loci for a comprehensive view of phylogeographic history, and that mtDNA-based phylogeographic studies of many mammals should be reevaluated. Recent advances in sequencing technology render the analysis of Y-chromosomal variation feasible, even in nonmodel organisms. PMID:24667925

  17. Sex− and species−biased gene flow in a spotted eagle hybrid zone

    Directory of Open Access Journals (Sweden)

    Väli Ülo

    2011-04-01

    Full Text Available Abstract Background Recent theoretical and empirical work points toward a significant role for sex-chromosome linked genes in the evolution of traits that induce reproductive isolation and for traits that evolve under influence of sexual selection. Empirical studies including recently diverged (Pleistocene, short-lived avian species pairs with short generation times have found that introgression occurs on the autosomes but not on the Z-chromosome. Here we study genetic differentiation and gene flow in the long-lived greater spotted eagle (Aquila clanga and lesser spotted eagle (A. pomarina, two species with comparatively long generation times. Results Our data suggest that there is a directional bias in migration rates between hybridizing spotted eagles in eastern Europe. We find that a model including post divergence gene flow fits our data best for both autosomal and Z-chromosome linked loci but, for the Z-chromosome, the rate is reduced in the direction from A. pomarina to A. clanga. Conclusions The fact that some introgression still occurs on the Z-chromosome between these species suggests that the differentiation process is in a more premature phase in our study system than in previously studied avian species pairs and that could be explained by a shorter divergence time and/or a longer average generation time in the spotted eagles. The results are in agreement with field observations and provide further insight into the role of sex-linked loci for the build-up of barriers to gene flow among diverging populations and species.

  18. Analysis of interchromosomal mitotic recombination.

    Science.gov (United States)

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

    1990-07-01

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

  19. Changes in base composition bias of nuclear and mitochondrial genes in lice (Insecta: Psocodea).

    Science.gov (United States)

    Yoshizawa, Kazunori; Johnson, Kevin P

    2013-12-01

    While it is well known that changes in the general processes of molecular evolution have occurred on a variety of timescales, the mechanisms underlying these changes are less well understood. Parasitic lice ("Phthiraptera") and their close relatives (infraorder Nanopsocetae of the insect order Psocodea) are a group of insects well known for their unusual features of molecular evolution. We examined changes in base composition across parasitic lice and bark lice. We identified substantial differences in percent GC content between the clade comprising parasitic lice plus closely related bark lice (=Nanopsocetae) versus all other bark lice. These changes occurred for both nuclear and mitochondrial protein coding and ribosomal RNA genes, often in the same direction. To evaluate whether correlations in base composition change also occurred within lineages, we used phylogenetically controlled comparisons, and in this case few significant correlations were identified. Examining more constrained sites (first/second codon positions and rRNA) revealed that, in comparison to the other bark lice, the GC content of parasitic lice and close relatives tended towards 50 % either up from less than 50 % GC or down from greater than 50 % GC. In contrast, less constrained sites (third codon positions) in both nuclear and mitochondrial genes showed less of a consistent change of base composition in parasitic lice and very close relatives. We conclude that relaxed selection on this group of insects is a potential explanation of the change in base composition for both mitochondrial and nuclear genes, which could lead to nucleotide frequencies closer to random expectation (i.e., 50 % GC) in the absence of any mutation bias. Evidence suggests this relaxed selection arose once in the non-parasitic common ancestor of Phthiraptera + Nanopsocetae and is not directly related to the evolution of the parasitism in lice. PMID:24233690

  20. Differential effect of aneuploidy on the X chromosome and genes with sex-biased expression in Drosophila.

    Science.gov (United States)

    Sun, Lin; Johnson, Adam F; Li, Jilong; Lambdin, Aaron S; Cheng, Jianlin; Birchler, James A

    2013-10-01

    Global analysis of gene expression via RNA sequencing was conducted for trisomics for the left arm of chromosome 2 (2L) and compared with the normal genotype. The predominant response of genes on 2L was dosage compensation in that similar expression occurred in the trisomic compared with the diploid control. However, the male and female trisomic/normal expression ratio distributions for 2L genes differed in that females also showed a strong peak of genes with increased expression and males showed a peak of reduced expression relative to the opposite sex. For genes in other autosomal regions, the predominant response to trisomy was reduced expression to the inverse of the altered chromosomal dosage (2/3), but a minor peak of increased expression in females and further reduced expression in males were also found, illustrating a sexual dimorphism for the response to aneuploidy. Moreover, genes with sex-biased expression as revealed by comparing amounts in normal males and females showed responses of greater magnitude to trisomy 2L, suggesting that the genes involved in dosage-sensitive aneuploid effects also influence sex-biased expression. Each autosomal chromosome arm responded to 2L trisomy similarly, but the ratio distributions for X-linked genes were distinct in both sexes, illustrating an X chromosome-specific response to aneuploidy.

  1. Genes: Interactions with Language on Three Levels—Inter-Individual Variation, Historical Correlations and Genetic Biasing

    Science.gov (United States)

    Dediu, Dan

    The complex inter-relationships between genetics and linguistics encompass all four scales highlighted by the contributions to this book and, together with cultural transmission, the genetics of language holds the promise to offer a unitary understanding of this fascinating phenomenon. There are inter-individual differences in genetic makeup which contribute to the obvious fact that we are not identical in the way we understand and use language and, by studying them, we will be able to both better treat and enhance ourselves. There are correlations between the genetic configuration of human groups and their languages, reflecting the historical processes shaping them, and there also seem to exist genes which can influence some characteristics of language, biasing it towards or against certain states by altering the way language is transmitted across generations. Besides the joys of pure knowledge, the understanding of these three aspects of genetics relevant to language will potentially trigger advances in medicine, linguistics, psychology or the understanding of our own past and, last but not least, a profound change in the way we regard one of the emblems of being human: our capacity for language.

  2. Y-chromosomal diversity in Haiti and Jamaica: contrasting levels of sex-biased gene flow.

    Science.gov (United States)

    Simms, Tanya M; Wright, Marisil R; Hernandez, Michelle; Perez, Omar A; Ramirez, Evelyn C; Martinez, Emanuel; Herrera, Rene J

    2012-08-01

    Although previous studies have characterized the genetic structure of populations from Haiti and Jamaica using classical and autosomal STR polymorphisms, the patrilineal influences that are present in these countries have yet to be explored. To address this lacuna, the current study aims to investigate, for the first time, the potential impact of different ancestral sources, unique colonial histories, and distinct family structures on the paternal profile of both groups. According to previous reports examining populations from the Americas, island-specific demographic histories can greatly impact population structure, including various patterns of sex-biased gene flow. Also, given the contrasting autosomal profiles provided in our earlier study (Simms et al.: Am J Phys Anthropol 142 (2010) 49-66), we hypothesize that the degree and directionality of gene flow from Europeans, Africans, Amerindians, and East Asians are dissimilar in the two countries. To test this premise, 177 high-resolution Y-chromosome binary markers and 17 Y-STR loci were typed in Haiti (n = 123) and Jamaica (n = 159) and subsequently utilized for phylogenetic comparisons to available reference collections encompassing Africa, Europe, Asia (East and South), and the New World. Our results reveal that both studied populations exhibit a predominantly South-Saharan paternal component, with haplogroups A1b-V152, A3-M32, B2-M182, E1a-M33, E1b1a-M2, E2b-M98, and R1b2-V88 comprising 77.2% and 66.7% of the Haitian and Jamaican paternal gene pools, respectively. Yet, European derived chromosomes (i.e., haplogroups G2a*-P15, I-M258, R1b1b-M269, and T-M184) were detected at commensurate levels in Haiti (20.3%) and Jamaica (18.9%), whereas Y-haplogroups indicative of Chinese [O-M175 (3.8%)] and Indian [H-M69 (0.6%) and L-M20 (0.6%)] ancestry were restricted to Jamaica. PMID:22576450

  3. Male- and Female-Biased Gene Expression of Olfactory-Related Genes in the Antennae of Asian Corn Borer, Ostrinia furnacalis (Guenée) (Lepidoptera: Crambidae).

    Science.gov (United States)

    Zhang, Tiantao; Coates, Brad S; Ge, Xing; Bai, Shuxiong; He, Kanglai; Wang, Zhenying

    2015-01-01

    The Asian corn borer (ACB), Ostrinia furnacalis (Guenée), is a destructive pest insect of cultivated corn crops, for which antennal-expressed receptors are important to detect olfactory cues for mate attraction and oviposition. Few olfactory related genes were reported in ACB, so we sequenced and characterized the transcriptome of male and female O. furnacalis antennae. Non-normalized male and female O. furnacalis antennal cDNA libraries were sequenced on the Illumina HiSeq 2000 and assembled into a reference transcriptome. Functional gene annotations identified putative olfactory-related genes; 56 odorant receptors (ORs), 23 odorant binding proteins (OBPs), and 10 CSPs. RNA-seq estimates of gene expression respectively showed up- and down-regulation of 79 and 30 genes in female compared to male antennae, which included up-regulation of 8 ORs and 1 PBP gene in male antennae as well as 3 ORs in female antennae. Quantitative real-time RT-PCR analyses validated strong male antennal-biased expression of OfurOR3, 4, 6, 7, 8, 11, 12, 13 and 14 transcripts, whereas OfurOR17 and 18 were specially expressed in female antennae. Sex-biases gene expression described here provides important insight in gene functionalization, and provides candidate genes putatively involved in environmental perception, host plant attraction, and mate recognition. PMID:26062030

  4. Male- and Female-Biased Gene Expression of Olfactory-Related Genes in the Antennae of Asian Corn Borer, Ostrinia furnacalis (Guenee (Lepidoptera: Crambidae.

    Directory of Open Access Journals (Sweden)

    Tiantao Zhang

    Full Text Available The Asian corn borer (ACB, Ostrinia furnacalis (Guenée, is a destructive pest insect of cultivated corn crops, for which antennal-expressed receptors are important to detect olfactory cues for mate attraction and oviposition. Few olfactory related genes were reported in ACB, so we sequenced and characterized the transcriptome of male and female O. furnacalis antennae. Non-normalized male and female O. furnacalis antennal cDNA libraries were sequenced on the Illumina HiSeq 2000 and assembled into a reference transcriptome. Functional gene annotations identified putative olfactory-related genes; 56 odorant receptors (ORs, 23 odorant binding proteins (OBPs, and 10 CSPs. RNA-seq estimates of gene expression respectively showed up- and down-regulation of 79 and 30 genes in female compared to male antennae, which included up-regulation of 8 ORs and 1 PBP gene in male antennae as well as 3 ORs in female antennae. Quantitative real-time RT-PCR analyses validated strong male antennal-biased expression of OfurOR3, 4, 6, 7, 8, 11, 12, 13 and 14 transcripts, whereas OfurOR17 and 18 were specially expressed in female antennae. Sex-biases gene expression described here provides important insight in gene functionalization, and provides candidate genes putatively involved in environmental perception, host plant attraction, and mate recognition.

  5. Cell-type-specific repression by methyl-CpG-binding protein 2 is biased toward long genes.

    Science.gov (United States)

    Sugino, Ken; Hempel, Chris M; Okaty, Benjamin W; Arnson, Hannah A; Kato, Saori; Dani, Vardhan S; Nelson, Sacha B

    2014-09-17

    Mutations in methyl-CpG-binding protein 2 (MeCP2) cause Rett syndrome and related autism spectrum disorders (Amir et al., 1999). MeCP2 is believed to be required for proper regulation of brain gene expression, but prior microarray studies in Mecp2 knock-out mice using brain tissue homogenates have revealed only subtle changes in gene expression (Tudor et al., 2002; Nuber et al., 2005; Jordan et al., 2007; Chahrour et al., 2008). Here, by profiling discrete subtypes of neurons we uncovered more dramatic effects of MeCP2 on gene expression, overcoming the "dilution problem" associated with assaying homogenates of complex tissues. The results reveal misregulation of genes involved in neuronal connectivity and communication. Importantly, genes upregulated following loss of MeCP2 are biased toward longer genes but this is not true for downregulated genes, suggesting MeCP2 may selectively repress long genes. Because genes involved in neuronal connectivity and communication, such as cell adhesion and cell-cell signaling genes, are enriched among longer genes, their misregulation following loss of MeCP2 suggests a possible etiology for altered circuit function in Rett syndrome. PMID:25232122

  6. Micromechanics of human mitotic chromosomes

    International Nuclear Information System (INIS)

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

  7. Biased hypermutation occurred frequently in a gene inserted into the IC323 recombinant measles virus during its persistence in the brains of nude mice

    Energy Technology Data Exchange (ETDEWEB)

    Otani, Sanae [Department of Virology and Graduate School of Medicine, Osaka City University, 1-4-3 Asahimachi, Abeno-ku, Osaka 545-8585 (Japan); Department of Pediatrics, Graduate School of Medicine, Osaka City University, Osaka (Japan); Ayata, Minoru, E-mail: maverick@med.osaka-cu.ac.jp [Department of Virology and Graduate School of Medicine, Osaka City University, 1-4-3 Asahimachi, Abeno-ku, Osaka 545-8585 (Japan); Takeuchi, Kaoru [Laboratory of Environmental Microbiology, Division of Biomedical Science, Faculty of Medicine, University of Tsukuba, Ibaraki (Japan); Takeda, Makoto [Department of Virology 3, National Institute of Infectious Diseases, Tokyo (Japan); Shintaku, Haruo [Department of Pediatrics, Graduate School of Medicine, Osaka City University, Osaka (Japan); Ogura, Hisashi [Department of Virology and Graduate School of Medicine, Osaka City University, 1-4-3 Asahimachi, Abeno-ku, Osaka 545-8585 (Japan)

    2014-08-15

    Measles virus (MV) is the causative agent of measles and its neurological complications, subacute sclerosing panencephalitis (SSPE) and measles inclusion body encephalitis (MIBE). Biased hypermutation in the M gene is a characteristic feature of SSPE and MIBE. To determine whether the M gene is the preferred target of hypermutation, an additional transcriptional unit containing a humanized Renilla reniformis green fluorescent protein (hrGFP) gene was introduced into the IC323 MV genome, and nude mice were inoculated intracerebrally with the virus. Biased hypermutation occurred in the M gene and also in the hrGFP gene when it was inserted between the leader and the N gene, but not between the H and L gene. These results indicate that biased hypermutation is usually found in a gene whose function is not essential for viral proliferation in the brain and that the location of a gene in the MV genome can affect its mutational frequency. - Highlights: • Wild-type MV can cause persistent infections in nude mice. • Biased hypermutation occurred in the M gene. • Biased hypermutation occurred in an inessential gene inserted between the leader and the N gene.

  8. Cdc20 control of cell fate during prolonged mitotic arrest

    DEFF Research Database (Denmark)

    Nilsson, Jakob

    2011-01-01

    The fate of cells arrested in mitosis by antimitotic compounds is complex but is influenced by competition between pathways promoting cell death and pathways promoting mitotic exit. As components of both of these pathways are regulated by Cdc20-dependent degradation, I hypothesize that variations...... in Cdc20 protein levels, rather than mutations in checkpoint genes, could affect cell fate during prolonged mitotic arrest. This hypothesis is supported by experiments where manipulation of Cdc20 levels affects the response to antimitotic compounds. The observed differences in Cdc20 levels between cell...

  9. Mitotic Exit Control as an Evolved Complex System

    Energy Technology Data Exchange (ETDEWEB)

    Bosl, W; Li, R

    2005-04-25

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

  10. Nucleotide composition bias and codon usage trends of gene populations in Mycoplasma capricolum subsp. capricolum and M. agalactiae

    Indian Academy of Sciences (India)

    Xiao-Xia Ma; Yu-Ping Feng; Jia-Ling Bai; De-Rong Zhang; Xin-Shi Lin; Zhong-Ren Ma

    2015-06-01

    Because of the low GC content of the gene population, amino acids of the two mycoplasmas tend to be encoded by synonymous codons with an A or T end. Compared with the codon usage of ovine, Mycoplasma capricolum and M. agalactiae tend to select optimal codons, which are rare codons in ovine. Due to codon usage pattern caused by genes with key biological functions, the overall codon usage trends represent a certain evolutionary direction in the life cycle of the two mycoplasmas. The overall codon usage trends of a gene population of M. capricolum subsp. capricolum can be obviously separated from other mycoplasmas, and the overall codon usage trends of M. agalactiae are highly similar to those of M. bovis. These results partly indicate the independent evolution of the two mycoplasmas without the limits of the host cell’s environment. The GC and AT skews estimate nucleotide composition bias at different positions of nucleotide triplets and the protein consideration caused by the nucleotide composition bias at codon positions 1 and 2 largely take part in synonymous codon usage patterns of the two mycoplasmas. The correlation between the codon adaptation index and codon usage variation indicates that the effect of codon usage on gene expression in M. capricolum subsp. capricolum is opposite to that of M. agalactiae, further suggesting independence of the evolutionary process influencing the overall codon usage trends of gene populations of mycoplasmas.

  11. Differential gene expression and mitotic cell analysis of the drought tolerant soybean (Glycine max L. Merrill Fabales, Fabaceae cultivar MG/BR46 (Conquista under two water deficit induction systems

    Directory of Open Access Journals (Sweden)

    Polyana K. Martins

    2008-01-01

    Full Text Available Drought cause serious yield losses in soybean (Glycine max, roots being the first plant organ to detect the water-stress signals triggering defense mechanisms. We used two drought induction systems to identify genes differentially expressed in the roots of the drought-tolerant soybean cultivar MG/BR46 (Conquista and characterize their expression levels during water deficit. Soybean plants grown in nutrient solution hydroponically and in sand-pots were submitted to water stress and gene expression analysis was conducted using the differential display (DD and real time polymerase chain reaction (PCR techniques. Three differentially expressed mRNA transcripts showed homology to the Antirrhinum majus basic helix-loop-helix transcription factor bHLH, the Arabidopsis thaliana phosphatidylinositol transfer protein PITP and the auxin-independent growth regulator 1 (axi 1. The hydroponic experiments showed that after 100 min outside the nutrient solution photosynthesis completely stopped, stomata closed and leaf temperature rose. Both stress induction treatments produced significant decrease in the mitotic indices of root cells. Axi 1, PITP and bHLH were not only differentially expressed during dehydration in the hydroponics experiments but also during induced drought in the pot experiments. Although, there were differences between the two sets of experiments in the time at which up or down regulation occurred, the expression pattern of all three transcripts was related. Similar gene expression and cytological analysis results occurred in both systems, suggesting that hydroponics could be used to simulate drought detection by roots growing in soil and thus facilitate rapid and easy root sampling.

  12. Dynamic, Sex-Differential STAT5 and BCL6 Binding to Sex-Biased, Growth Hormone-Regulated Genes in Adult Mouse Liver

    OpenAIRE

    Zhang, Yijing; Laz, Ekaterina V.; Waxman, David J.

    2012-01-01

    Sex-dependent pituitary growth hormone (GH) secretory patterns determine the sex-biased expression of >1,000 genes in mouse and rat liver, affecting lipid and drug metabolism, inflammation, and disease. A fundamental biological question is how robust differential expression can be achieved for hundreds of sex-biased genes simply based on the GH input signal pattern: pulsatile GH stimulation in males versus near-continuous GH exposure in females. STAT5 is an essential transcriptional mediator ...

  13. Impact of bias discrepancy and amino acid usage on estimates of the effective number of codons used in a gene, and a test for selection on codon usage

    DEFF Research Database (Denmark)

    Fuglsang, Anders

    2007-01-01

    The effective number of codons (Nc) used in a gene is one of the most commonly used measures of synonymous codon usage bias, owing much of its popularity to the fact that it is species independent and that simulation studies have shown that it is less dependent of gene length than other measures....... literature that exists for Buchnera sp. APS and Borrelia burgdorferi....

  14. Chromosome-biased binding and gene regulation by the Caenorhabditis elegans DRM complex.

    Directory of Open Access Journals (Sweden)

    Tomoko M Tabuchi

    2011-05-01

    Full Text Available DRM is a conserved transcription factor complex that includes E2F/DP and pRB family proteins and plays important roles in development and cancer. Here we describe new aspects of DRM binding and function revealed through genome-wide analyses of the Caenorhabditis elegans DRM subunit LIN-54. We show that LIN-54 DNA-binding activity recruits DRM to promoters enriched for adjacent putative E2F/DP and LIN-54 binding sites, suggesting that these two DNA-binding moieties together direct DRM to its target genes. Chromatin immunoprecipitation and gene expression profiling reveals conserved roles for DRM in regulating genes involved in cell division, development, and reproduction. We find that LIN-54 promotes expression of reproduction genes in the germline, but prevents ectopic activation of germline-specific genes in embryonic soma. Strikingly, C. elegans DRM does not act uniformly throughout the genome: the DRM recruitment motif, DRM binding, and DRM-regulated embryonic genes are all under-represented on the X chromosome. However, germline genes down-regulated in lin-54 mutants are over-represented on the X chromosome. We discuss models for how loss of autosome-bound DRM may enhance germline X chromosome silencing. We propose that autosome-enriched binding of DRM arose in C. elegans as a consequence of germline X chromosome silencing and the evolutionary redistribution of germline-expressed and essential target genes to autosomes. Sex chromosome gene regulation may thus have profound evolutionary effects on genome organization and transcriptional regulatory networks.

  15. Synonymous codon usage bias in plant mitochondrial genes is associated with intron number and mirrors species evolution.

    Directory of Open Access Journals (Sweden)

    Wenjing Xu

    Full Text Available Synonymous codon usage bias (SCUB is a common event that a non-uniform usage of codons often occurs in nearly all organisms. We previously found that SCUB is correlated with both intron number and exon position in the plant nuclear genome but not in the plastid genome; SCUB in both nuclear and plastid genome can mirror the evolutionary specialization. However, how about the rules in the mitochondrial genome has not been addressed. Here, we present an analysis of SCUB in the mitochondrial genome, based on 24 plant species ranging from algae to land plants. The frequencies of NNA and NNT (A- and T-ending codons are higher than those of NNG and NNC, with the strongest preference in bryophytes and the weakest in land plants, suggesting an association between SCUB and plant evolution. The preference for NNA and NNT is more evident in genes harboring a greater number of introns in land plants, but the bias to NNA and NNT exhibits even among exons. The pattern of SCUB in the mitochondrial genome differs in some respects to that present in both the nuclear and plastid genomes.

  16. Synonymous Codon Usage Bias in the Plastid Genome is Unrelated to Gene Structure and Shows Evolutionary Heterogeneity.

    Science.gov (United States)

    Qi, Yueying; Xu, Wenjing; Xing, Tian; Zhao, Mingming; Li, Nana; Yan, Li; Xia, Guangmin; Wang, Mengcheng

    2015-01-01

    Synonymous codon usage bias (SCUB) is the nonuniform usage of codons, occurring often in nearly all organisms. Our previous study found that SCUB is correlated with intron number, is unequal among exons in the plant nuclear genome, and mirrors evolutionary specialization. However, whether this rule exists in the plastid genome has not been addressed. Here, we present an analysis of SCUB in the plastid genomes of 25 species from lower to higher plants (algae, bryophytes, pteridophytes, gymnosperms, and spermatophytes). We found NNA and NNT (A- and T-ending codons) are preferential in the plastid genomes of all plants. Interestingly, this preference is heterogeneous among taxonomies of plants, with the strongest preference in bryophytes and the weakest in pteridophytes, suggesting an association between SCUB and plant evolution. In addition, SCUB frequencies are consistent among genes with varied introns and among exons, indicating that the bias of NNA and NNT is unrelated to either intron number or exon position. Further, SCUB is associated with DNA methylation-induced conversion of cytosine to thymine in the vascular plants but not in algae or bryophytes. These data demonstrate that these SCUB profiles in the plastid genome are distinctly different compared with the nuclear genome.

  17. Sex bias in copy number variation of olfactory receptor gene family depends on ethnicity

    OpenAIRE

    Farideh eShadravan

    2013-01-01

    Gender plays a pivotal role in the human genetic identity and is also manifested in many genetic disorders particularly mental retardation. In this study its effect on copy number variation (CNV), known to cause genetic disorders was explored. As the olfactory receptor (OR) repertoire comprises the largest human gene family, it was selected for this study, which was carried out within and between three populations, derived from 150 individuals from the 1000 Genome Project. Analysis of 3872 CN...

  18. PICH promotes mitotic chromosome segregation

    DEFF Research Database (Denmark)

    Nielsen, Christian Thomas Friberg; Hickson, Ian D

    2016-01-01

    PICH is an SNF2-family DNA translocase that appears to play a role specifically in mitosis. Characterization of PICH in human cells led to the initial discovery of "ultra-fine DNA bridges" (UFBs) that connect the 2 segregating DNA masses in the anaphase of mitosis. These bridge structures, which...... arise from specific regions of the genome, are a normal feature of anaphase but had escaped detection previously because they do not stain with commonly used DNA dyes. Nevertheless, UFBs are important for genome maintenance because defects in UFB resolution can lead to cytokinesis failure. We reported...... recently that PICH stimulates the unlinking (decatenation) of entangled DNA by Topoisomerase IIα (Topo IIα), and is important for the resolution of UFBs. We also demonstrated that PICH and Topo IIα co-localize at the rDNA (rDNA). In this Extra View article, we discuss the mitotic roles of PICH and explore...

  19. D-subgenome bias of Xcm resistance genes in tetraploid Gossypium (cotton) suggests that polyploid formation has created novel avenues for evolution.

    Science.gov (United States)

    Wright, R J; Thaxton, P M; El-Zik, K M; Paterson, A H

    1998-08-01

    A detailed RFLP map was used to determine the chromosomal locations and subgenomic distributions of cotton (Gossypium) genes/QTLs that confer resistance to the bacterial blight pathogen, Xanthomonas campestris pv. malvacearum (Xcm). Genetic mapping generally corroborated classic predictions regarding the number and dosage effects of genes conferring Xcm resistance. One recessive allele (b6) was a noteworthy exception to the genetic dominance of most plant resistance alleles. This recessive allele appeared to uncover additional QTLs from both resistant and ostensibly susceptible genotypes, some of which corresponded in location to resistance (R)-genes effective against other Xcm races. One putatively "defeated" resistance allele (B3) reduced severity of Xcm damage by "virulent" races. Among the six resistance genes derived from tetraploid cottons, five (83%) mapped to D-subgenome chromosomes-if each subgenome were equally likely to evolve new R-gene alleles, this level of bias would occur in only about 1.6% of cases. Possible explanations of this bias include biogeographic factors, differences in evolutionary rates between subgenomes, gene conversion or other intergenomic exchanges that escaped detection by genetic mapping, or other factors. A significant D-subgenome bias of Xcm resistance genes may suggest that polyploid formation has offered novel avenues for phenotypic response to selection.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-02-01

    Microtubule poisons and other anti-mitotic drugs induce tumor death but the molecular events linking mitotic arrest to cell death are still not fully understood. We have analyzed cell fate after mitotic arrest produced by the microtubule-destabilizing drug vincristine in a panel of human tumor cell lines showing different response to vincristine. In Jurkat, RPMI 8226 and HeLa cells, apoptosis was triggered shortly after vincristine-induced mitotic arrest. However, A549 cells, which express a great amount of Bcl-x{sub L} and undetectable amounts of Bak, underwent mitotic slippage prior to cell death. However, when Bcl-x{sub L} gene was silenced in A549 cells, vincristine induced apoptosis during mitotic arrest. Another different behavior was found in MiaPaca2 cells, where vincristine caused death by mitotic catastrophe that switched to apoptosis when cyclin B1 degradation was prevented by proteasome inhibition. Overexpression of Bcl-x{sub L} or silencing Bax and Bak expression delayed the onset of apoptosis in Jurkat and RPMI 8226 cells, enabling mitotic slippage and endoreduplication. In HeLa cells, overexpression of Bcl-x{sub L} switched cell death from apoptosis to mitotic catastrophe. Mcl-1 offered limited protection to vincristine-induced cell death and Mcl-1 degradation was not essential for vincristine-induced death. All these results, taken together, indicate that the Bcl-x{sub L}/Bak ratio and the ability to degrade cyclin B1 determine cell fate after mitotic arrest in the different tumor cell types. Highlights: ► Vincristine induces cell death by apoptosis or mitotic catastrophe. ► Apoptosis-proficient cells die by apoptosis during mitosis upon vincristine treatment. ► p53wt apoptosis-deficient cells undergo apoptosis from a G1-like tetraploid state. ► p53mt apoptosis-deficient cells can survive and divide giving rise to 8N cells.

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

    Science.gov (United States)

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

    2015-08-14

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

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

    Science.gov (United States)

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

    2015-01-01

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

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

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    Rajiv C McCoy

    2015-10-01

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

  4. Recombination Rate Variation Modulates Gene Sequence Evolution Mainly via GC-Biased Gene Conversion, Not Hill-Robertson Interference, in an Avian System.

    Science.gov (United States)

    Bolívar, Paulina; Mugal, Carina F; Nater, Alexander; Ellegren, Hans

    2016-01-01

    The ratio of nonsynonymous to synonymous substitution rates (ω) is often used to measure the strength of natural selection. However, ω may be influenced by linkage among different targets of selection, that is, Hill-Robertson interference (HRI), which reduces the efficacy of selection. Recombination modulates the extent of HRI but may also affect ω by means of GC-biased gene conversion (gBGC), a process leading to a preferential fixation of G:C ("strong," S) over A:T ("weak," W) alleles. As HRI and gBGC can have opposing effects on ω, it is essential to understand their relative impact to make proper inferences of ω. We used a model that separately estimated S-to-S, S-to-W, W-to-S, and W-to-W substitution rates in 8,423 avian genes in the Ficedula flycatcher lineage. We found that the W-to-S substitution rate was positively, and the S-to-W rate negatively, correlated with recombination rate, in accordance with gBGC but not predicted by HRI. The W-to-S rate further showed the strongest impact on both dN and dS. However, since the effects were stronger at 4-fold than at 0-fold degenerated sites, likely because the GC content of these sites is farther away from its equilibrium, ω slightly decreases with increasing recombination rate, which could falsely be interpreted as a consequence of HRI. We corroborated this hypothesis analytically and demonstrate that under particular conditions, ω can decrease with increasing recombination rate. Analyses of the site-frequency spectrum showed that W-to-S mutations were skewed toward high, and S-to-W mutations toward low, frequencies, consistent with a prevalent gBGC-driven fixation bias.

  5. The removal of multiplicative, systematic bias allows integration of breast cancer gene expression datasets – improving meta-analysis and prediction of prognosis

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    Pepper Stuart D

    2008-09-01

    Full Text Available Abstract Background The number of gene expression studies in the public domain is rapidly increasing, representing a highly valuable resource. However, dataset-specific bias precludes meta-analysis at the raw transcript level, even when the RNA is from comparable sources and has been processed on the same microarray platform using similar protocols. Here, we demonstrate, using Affymetrix data, that much of this bias can be removed, allowing multiple datasets to be legitimately combined for meaningful meta-analyses. Results A series of validation datasets comparing breast cancer and normal breast cell lines (MCF7 and MCF10A were generated to examine the variability between datasets generated using different amounts of starting RNA, alternative protocols, different generations of Affymetrix GeneChip or scanning hardware. We demonstrate that systematic, multiplicative biases are introduced at the RNA, hybridization and image-capture stages of a microarray experiment. Simple batch mean-centering was found to significantly reduce the level of inter-experimental variation, allowing raw transcript levels to be compared across datasets with confidence. By accounting for dataset-specific bias, we were able to assemble the largest gene expression dataset of primary breast tumours to-date (1107, from six previously published studies. Using this meta-dataset, we demonstrate that combining greater numbers of datasets or tumours leads to a greater overlap in differentially expressed genes and more accurate prognostic predictions. However, this is highly dependent upon the composition of the datasets and patient characteristics. Conclusion Multiplicative, systematic biases are introduced at many stages of microarray experiments. When these are reconciled, raw data can be directly integrated from different gene expression datasets leading to new biological findings with increased statistical power.

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

    Science.gov (United States)

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

    2015-01-01

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

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

    Science.gov (United States)

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

    1997-01-01

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

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

    Science.gov (United States)

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

    2011-01-01

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

  9. Continued stabilization of the nuclear higher-order structure of post-mitotic neurons in vivo.

    Directory of Open Access Journals (Sweden)

    Janeth Alva-Medina

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

  10. 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

    2015-11-01

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

  11. Is GC bias in the nuclear genome of the carnivorous plant Utricularia driven by ROS-based mutation and biased gene conversion?

    OpenAIRE

    Ibarra-Laclette, Enrique; Albert, Victor A.; Herrera-Estrella, Alfredo; Herrera-Estrella, Luis

    2011-01-01

    At less than 90 Mbp, the tiny nuclear genome of the carnivorous bladderwort plant Utricularia is an attractive model system for studying molecular evolutionary processes leading to genome miniaturization. Recently, we reported that expression of genes encoding DNA repair and reactive oxygen species (ROS) detoxification enzymes is highest in Utricularia traps, and we argued that ROS mutagenic action correlates with the high nucleotide substitution rates observed in the Utricularia plastid, mit...

  12. New mitotic regulators released from chromatin

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    Hideki eYokoyama

    2013-12-01

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

  13. Male-biased aganglionic megacolon in the TashT mouse line due to perturbation of silencer elements in a large gene desert of chromosome 10.

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    Karl-F Bergeron

    2015-03-01

    Full Text Available Neural crest cells (NCC are a transient migratory cell population that generates diverse cell types such as neurons and glia of the enteric nervous system (ENS. Via an insertional mutation screen for loci affecting NCC development in mice, we identified one line-named TashT-that displays a partially penetrant aganglionic megacolon phenotype in a strong male-biased manner. Interestingly, this phenotype is highly reminiscent of human Hirschsprung's disease, a neurocristopathy with a still unexplained male sex bias. In contrast to the megacolon phenotype, colonic aganglionosis is almost fully penetrant in homozygous TashT animals. The sex bias in megacolon expressivity can be explained by the fact that the male ENS ends, on average, around a "tipping point" of minimal colonic ganglionosis while the female ENS ends, on average, just beyond it. Detailed analysis of embryonic intestines revealed that aganglionosis in homozygous TashT animals is due to slower migration of enteric NCC. The TashT insertional mutation is localized in a gene desert containing multiple highly conserved elements that exhibit repressive activity in reporter assays. RNAseq analyses and 3C assays revealed that the TashT insertion results, at least in part, in NCC-specific relief of repression of the uncharacterized gene Fam162b; an outcome independently confirmed via transient transgenesis. The transcriptional signature of enteric NCC from homozygous TashT embryos is also characterized by the deregulation of genes encoding members of the most important signaling pathways for ENS formation-Gdnf/Ret and Edn3/Ednrb-and, intriguingly, the downregulation of specific subsets of X-linked genes. In conclusion, this study not only allowed the identification of Fam162b coding and regulatory sequences as novel candidate loci for Hirschsprung's disease but also provides important new insights into its male sex bias.

  14. Neurons That Underlie Drosophila melanogaster Reproductive Behaviors: Detection of a Large Male-Bias in Gene Expression in fruitless-Expressing Neurons

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    Nicole R. Newell

    2016-08-01

    Full Text Available Male and female reproductive behaviors in Drosophila melanogaster are vastly different, but neurons that express sex-specifically spliced fruitless transcripts (fru P1 underlie these behaviors in both sexes. How this set of neurons can generate such different behaviors between the two sexes is an unresolved question. A particular challenge is that fru P1-expressing neurons comprise only 2–5% of the adult nervous system, and so studies of adult head tissue or whole brain may not reveal crucial differences. Translating Ribosome Affinity Purification (TRAP identifies the actively translated pool of mRNAs from fru P1-expressing neurons, allowing a sensitive, cell-type-specific assay. We find four times more male-biased than female-biased genes in TRAP mRNAs from fru P1-expressing neurons. This suggests a potential mechanism to generate dimorphism in behavior. The male-biased genes may direct male behaviors by establishing cell fate in a similar context of gene expression observed in females. These results suggest a possible global mechanism for how distinct behaviors can arise from a shared set of neurons.

  15. Neurons That Underlie Drosophila melanogaster Reproductive Behaviors: Detection of a Large Male-Bias in Gene Expression in fruitless-Expressing Neurons

    Science.gov (United States)

    Newell, Nicole R.; New, Felicia N.; Dalton, Justin E.; McIntyre, Lauren M.; Arbeitman, Michelle N.

    2016-01-01

    Male and female reproductive behaviors in Drosophila melanogaster are vastly different, but neurons that express sex-specifically spliced fruitless transcripts (fru P1) underlie these behaviors in both sexes. How this set of neurons can generate such different behaviors between the two sexes is an unresolved question. A particular challenge is that fru P1-expressing neurons comprise only 2–5% of the adult nervous system, and so studies of adult head tissue or whole brain may not reveal crucial differences. Translating Ribosome Affinity Purification (TRAP) identifies the actively translated pool of mRNAs from fru P1-expressing neurons, allowing a sensitive, cell-type-specific assay. We find four times more male-biased than female-biased genes in TRAP mRNAs from fru P1-expressing neurons. This suggests a potential mechanism to generate dimorphism in behavior. The male-biased genes may direct male behaviors by establishing cell fate in a similar context of gene expression observed in females. These results suggest a possible global mechanism for how distinct behaviors can arise from a shared set of neurons. PMID:27247289

  16. Experimentally increased codon bias in the Drosophila Adh gene leads to an increase in larval, but not adult, alcohol dehydrogenase activity.

    Science.gov (United States)

    Hense, Winfried; Anderson, Nathan; Hutter, Stephan; Stephan, Wolfgang; Parsch, John; Carlini, David B

    2010-02-01

    Although most amino acids can be encoded by more than one codon, the synonymous codons are not used with equal frequency. This phenomenon is known as codon bias and appears to be a universal feature of genomes. The translational selection hypothesis posits that the use of optimal codons, which match the most abundant species of isoaccepting tRNAs, results in increased translational efficiency and accuracy. Previous work demonstrated that the experimental reduction of codon bias in the Drosophila alcohol dehydrogenase (Adh) gene led to a significant decrease in ADH protein expression. In this study we performed the converse experiment: we replaced seven suboptimal leucine codons that occur naturally in the Drosophila melanogaster Adh gene with the optimal codon. We then compared the in vivo ADH activities imparted by the wild-type and mutant alleles. The introduction of optimal leucine codons led to an increase in ADH activity in third-instar larvae. In adult flies, however, the introduction of optimal codons led to a decrease in ADH activity. There is no evidence that other selectively constrained features of the Adh gene, or its rate of transcription, were altered by the synonymous replacements. These results are consistent with translational selection for codon bias being stronger in the larval stage and suggest that there may be a selective conflict over optimal codon usage between different developmental stages.

  17. Neurons That Underlie Drosophila melanogaster Reproductive Behaviors: Detection of a Large Male-Bias in Gene Expression in fruitless-Expressing Neurons.

    Science.gov (United States)

    Newell, Nicole R; New, Felicia N; Dalton, Justin E; McIntyre, Lauren M; Arbeitman, Michelle N

    2016-01-01

    Male and female reproductive behaviors in Drosophila melanogaster are vastly different, but neurons that express sex-specifically spliced fruitless transcripts (fru P1) underlie these behaviors in both sexes. How this set of neurons can generate such different behaviors between the two sexes is an unresolved question. A particular challenge is that fru P1-expressing neurons comprise only 2-5% of the adult nervous system, and so studies of adult head tissue or whole brain may not reveal crucial differences. Translating Ribosome Affinity Purification (TRAP) identifies the actively translated pool of mRNAs from fru P1-expressing neurons, allowing a sensitive, cell-type-specific assay. We find four times more male-biased than female-biased genes in TRAP mRNAs from fru P1-expressing neurons. This suggests a potential mechanism to generate dimorphism in behavior. The male-biased genes may direct male behaviors by establishing cell fate in a similar context of gene expression observed in females. These results suggest a possible global mechanism for how distinct behaviors can arise from a shared set of neurons. PMID:27247289

  18. Radmis, a novel mitotic spindle protein that functions in cell division of neural progenitors.

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    Takahito Yumoto

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

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

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    Dina Dikovskaya

    2015-09-01

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

  20. Oncogenic KRAS triggers MAPK-dependent errors in mitosis and MYC-dependent sensitivity to anti-mitotic agents.

    Science.gov (United States)

    Perera, David; Venkitaraman, Ashok R

    2016-07-14

    Oncogenic KRAS induces cell proliferation and transformation, but little is known about its effects on cell division. Functional genetic screens have recently revealed that cancer cell lines expressing oncogenic KRAS are sensitive to interference with mitosis, but neither the mechanism nor the uniformity of anti-mitotic drug sensitivity connected with mutant KRAS expression are yet clear. Here, we report that acute expression of oncogenic KRAS in HeLa cells induces mitotic delay and defects in chromosome segregation through mitogen-activated protein kinase (MAPK) pathway activation and de-regulated expression of several mitosis-related genes. These anomalies are accompanied by increased sensitivity to anti-mitotic agents, a phenotype dependent on the transcription factor MYC and its downstream target anti-apoptotic protein BCL-XL. Unexpectedly, we find no correlation between KRAS mutational status or MYC expression levels and anti-mitotic drug sensitivity when surveying a large database of anti-cancer drug responses. However, we report that the co-existence of KRAS mutations and high MYC expression predicts anti-mitotic drug sensitivity. Our findings reveal a novel function of oncogenic KRAS in regulating accurate mitotic progression and suggest new avenues to therapeutically target KRAS-mutant tumours and stratify patients in ongoing clinical trials of anti-mitotic drugs.

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

    Science.gov (United States)

    Uz, Gulsen; Sarikaya, Aysegul Topal

    2016-01-01

    Magnesium (Mg2+), an essential ion for cells and biological systems, is involved in a variety of cellular processes, including the formation and breakdown of microtubules. The results of a previous investigation suggested that as cells grow the intracellular Mg2+ concentration falls, thereby stimulating formation of the mitotic spindle. In the present work, we used a Mg2+-deficient Schizosaccharomyces pombe strain GA2, in which two essential membrane Mg2+ transporter genes (homologs of ALR1 and ALR2 in Saccharomyces cerevisae) were deleted, and its parental strain Sp292, to examine the extent to which low Mg2+ concentrations can affect mitotic spindle formation. The two S. pombe strains were transformed with a plasmid carrying a GFP-α2-tubulin construct to fluorescently label microtubules. Using the free Mg2+-specific fluorescent probe mag-fura-2, we confirmed that intracellular free Mg2+ levels were lower in GA2 than in the parental strain. Defects in interphase microtubule organization, a lower percentage of mitotic spindle formation and a reduced mitotic index were also observed in the GA2 strain. Although there was interphase microtubule polymerization, the lower level of mitotic spindle formation in the Mg2+-deficient strain suggested a greater requirement for Mg2+ in this phenomenon than previously thought. PMID:27560651

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

    Science.gov (United States)

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

    2016-07-14

    Eukaryotic genomes are partitioned into chromosomes that form compact and spatially well-separated mechanical bodies during mitosis. This enables chromosomes to move independently of each other for segregation of precisely one copy of the genome to each of the nascent daughter cells. Despite insights into the spatial organization of mitotic chromosomes and the discovery of proteins at the chromosome surface, the molecular and biophysical bases of mitotic chromosome structural individuality have remained unclear. Here we report that the proliferation marker protein Ki-67 (encoded by the MKI67 gene), a component of the mitotic chromosome periphery, prevents chromosomes from collapsing into a single chromatin mass after nuclear envelope disassembly, thus enabling independent chromosome motility and efficient interactions with the mitotic spindle. The chromosome separation function of human Ki-67 is not confined within a specific protein domain, but correlates with size and net charge of truncation mutants that apparently lack secondary structure. This suggests that Ki-67 forms a steric and electrostatic charge barrier, similar to surface-active agents (surfactants) that disperse particles or phase-separated liquid droplets in solvents. Fluorescence correlation spectroscopy showed a high surface density of Ki-67 and dual-colour labelling of both protein termini revealed an extended molecular conformation, indicating brush-like arrangements that are characteristic of polymeric surfactants. Our study thus elucidates a biomechanical role of the mitotic chromosome periphery in mammalian cells and suggests that natural proteins can function as surfactants in intracellular compartmentalization. PMID:27362226

  3. p53 deficiency enhances mitotic arrest and slippage induced by pharmacological inhibition of Aurora kinases.

    Science.gov (United States)

    Marxer, M; Ma, H T; Man, W Y; Poon, R Y C

    2014-07-01

    A number of small-molecule inhibitors of Aurora kinases have been developed and are undergoing clinical trials for anti-cancer therapies. Different Aurora kinases, however, behave as very different targets: while inhibition of Aurora A (AURKA) induces a delay in mitotic exit, inhibition of Aurora B (AURKB) triggers mitotic slippage. Furthermore, while it is evident that p53 is regulated by Aurora kinase-dependent phosphorylation, how p53 may in turn regulate Aurora kinases remains mysterious. To address these issues, isogenic p53-containing and -negative cells were exposed to classic inhibitors that target both AURKA and AURKB (Alisertib and ZM447439), as well as to new generation of inhibitors that target AURKA (MK-5108), AURKB (Barasertib) individually. The fate of individual cells was then tracked with time-lapse microscopy. Remarkably, loss of p53, either by gene disruption or small interfering RNA-mediated depletion, sensitized cells to inhibition of both AURKA and AURKB, promoting mitotic arrest and slippage respectively. As the p53-dependent post-mitotic checkpoint is also important for preventing genome reduplication after mitotic slippage, these studies indicate that the loss of p53 in cancer cells represents a major opportunity for anti-cancer drugs targeting the Aurora kinases.

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

    Science.gov (United States)

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

    2016-06-29

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

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

    Science.gov (United States)

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

    2016-09-01

    In latent infection of Kaposi's sarcoma-associated herpesvirus (KSHV), viral gene expression is extremely limited and copy numbers of viral genomes remain constant. Latency-associated nuclear antigen (LANA) is known to have a role in maintaining viral genome copy numbers in growing cells. Several studies have shown that LANA is localized in particular regions on mitotic chromosomes, such as centromeres/pericentromeres. We independently examined the distinct localization of LANA on mitotic chromosomes during mitosis, using super-resolution laser confocal microscopy and correlative fluorescence microscopy-electron microscopy (FM-EM) analyses. We found that the majority of LANA were not localized at particular regions such as telomeres/peritelomeres, centromeres/pericentromeres, and cohesion sites, but at the bodies of condensed chromosomes. Thus, LANA may undergo various interactions with the host factors on the condensed chromosomes in order to tether the viral genome to mitotic chromosomes and realize faithful viral genome segregation during cell division. PMID:27254595

  6. Disruption of Mitotic Progression by Arsenic.

    Science.gov (United States)

    States, J Christopher

    2015-07-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-03-01

    Frequencies of coincident genetic events were measured in strain D7 of Saccharomyces cerevisiae. This diploid strain permits the detection of mitotic gene conversion involving the trp5-12 and trp5-27 alleles, mitotic crossing-over and gene conversion leading to the expression of the ade2-40 and ade2-119 alleles as red and pink colonies, and reversion of the ilv1-92 allele. The three genes are on different chromosomes, and one might expect that coincident (simultaneous) genetic alterations at two loci would occur at frequencies predicted by those of the single alterations acting as independent events. Contrary to this expectation, we observed that ade2 recombinants induced by bleomycin, {beta}-propiolactone, and ultraviolet radiation occur more frequently among trp5 convertants than among total colonies. This excess among trp5 recombinants indicates that double recombinants are more common than expected for independent events. No similar enrichment was found among Ilv{sup +} revertants. The possibility of an artifact in which haploid yeasts that mimic mitotic recombinants are generated by a low frequency of cryptic meiosis has been excluded. Several hypotheses that can explain the elevated incidence of coincident mitotic recombination have been evaluated, but the cause remains uncertain. Most evidence suggests that the excess is ascribable to a subset of the population being in a recombination-prone state.

  8. RBPJ, the major transcriptional effector of Notch signaling, remains associated with chromatin throughout mitosis, suggesting a role in mitotic bookmarking.

    Directory of Open Access Journals (Sweden)

    Robert J Lake

    2014-03-01

    Full Text Available Mechanisms that maintain transcriptional memory through cell division are important to maintain cell identity, and sequence-specific transcription factors that remain associated with mitotic chromatin are emerging as key players in transcriptional memory propagation. Here, we show that the major transcriptional effector of Notch signaling, RBPJ, is retained on mitotic chromatin, and that this mitotic chromatin association is mediated through the direct association of RBPJ with DNA. We further demonstrate that RBPJ binds directly to nucleosomal DNA in vitro, with a preference for sites close to the entry/exit position of the nucleosomal DNA. Genome-wide analysis in the murine embryonal-carcinoma cell line F9 revealed that roughly 60% of the sites occupied by RBPJ in asynchronous cells were also occupied in mitotic cells. Among them, we found that a fraction of RBPJ occupancy sites shifted between interphase and mitosis, suggesting that RBPJ can be retained on mitotic chromatin by sliding on DNA rather than disengaging from chromatin during mitotic chromatin condensation. We propose that RBPJ can function as a mitotic bookmark, marking genes for efficient transcriptional activation or repression upon mitotic exit. Strikingly, we found that sites of RBPJ occupancy were enriched for CTCF-binding motifs in addition to RBPJ-binding motifs, and that RBPJ and CTCF interact. Given that CTCF regulates transcription and bridges long-range chromatin interactions, our results raise the intriguing hypothesis that by collaborating with CTCF, RBPJ may participate in establishing chromatin domains and/or long-range chromatin interactions that could be propagated through cell division to maintain gene expression programs.

  9. Akt Inhibitor A-443654 Interferes with Mitotic Progression by Regulating Aurora A Kinase Expression

    Directory of Open Access Journals (Sweden)

    Xuesong Liu

    2008-08-01

    Full Text Available Both Akt and Aurora A kinase have been shown to be important targets for intervention for cancer therapy. We report here that Compound A (A-443654, a specific Akt inhibitor, interferes with mitotic progression and bipolar spindle formation. Compound A induces G2/M accumulation, defects in centrosome separation, and formation of either monopolar arrays or disorganized spindles. On the basis of gene expression array studies, we identified Aurora A as one of the genes regulated transcriptionally by Akt inhibitors including Compound A. Inhibition of the phosphatidylinositol 3-kinase (PI3K/Akt pathway, either by PI3K inhibitor LY294002 or by Compound A, dramatically inhibits the promoter activity of Aurora A, whereas the mammalian target of rapamycin inhibitor has little effect, suggesting that Akt might be responsible for up-regulating Aurora A for mitotic progression. Further analysis of the Aurora A promoter region indicates that the Ets element but not the Sp1 element is required for Compound A-sensitive transcriptional control of Aurora A. Overexpression of Aurora A in cells treated with Compound A attenuates the mitotic arrest and the defects in bipolar spindle formation induced by Akt inhibition. Our studies suggest that that Akt may promote mitotic progression through the transcriptional regulation of Aurora A.

  10. T-Cell Expression Cloning of Porphyromonas gingivalis Genes Coding for T Helper-Biased Immune Responses during Infection

    OpenAIRE

    Gonçalves, Reginaldo B.; Leshem, Onir; Bernards, Karen; Webb, John R; Stashenko, Philip P.; Campos-Neto, Antonio

    2006-01-01

    Exposure of the mouse oral cavity to Porphyromonas gingivalis results in the development of gingivitis and periapical bone loss, which apparently are associated with a Th1 response to bacterial antigens. We have used this infection model in conjunction with direct T-cell expression cloning to identify bacterial antigens that induce a preferential or biased T helper response during the infectious process. A P. gingivalis-specific CD4 T-cell line derived from mice at 3 weeks postchallenge was u...

  11. Measuring mitotic spindle dynamics in budding yeast

    Science.gov (United States)

    Plumb, Kemp

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

  12. The Mechanics of Mitotic Cell Rounding

    OpenAIRE

    Stewart, Martin

    2012-01-01

    During mitosis, adherent animal cells undergo a drastic shape change, from essentially flat to round, in a process known as mitotic cell rounding (MCR). The aim of this thesis was to critically examine the physical and biological basis of MCR. The experimental part of this thesis employed a combined optical microscope-atomic force microscope (AFM) setup in conjunction with flat tipless cantilevers to analyze cell mechanics, shape and volume. To this end, two AFM assays were developed: the ...

  13. Nuclear Chk1 prevents premature mitotic entry.

    Science.gov (United States)

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

    2011-07-01

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

  14. Nuclear Chk1 prevents premature mitotic entry.

    Science.gov (United States)

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

    2011-07-01

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

  15. Involvement of CNOT3 in mitotic progression through inhibition of MAD1 expression

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Akinori [Division of Oncology, Department of Cancer Biology, Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo 108-8639 (Japan); Kikuguchi, Chisato [Cell Signal Unit, Okinawa Institute of Science and Technology, Kunigami, Okinawa 904-0412 (Japan); Morita, Masahiro; Shimodaira, Tetsuhiro; Tokai-Nishizumi, Noriko; Yokoyama, Kazumasa; Ohsugi, Miho; Suzuki, Toru [Division of Oncology, Department of Cancer Biology, Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo 108-8639 (Japan); Yamamoto, Tadashi, E-mail: tyamamot@ims.u-tokyo.ac.jp [Division of Oncology, Department of Cancer Biology, Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo 108-8639 (Japan); Cell Signal Unit, Okinawa Institute of Science and Technology, Kunigami, Okinawa 904-0412 (Japan)

    2012-03-09

    Highlights: Black-Right-Pointing-Pointer CNOT3 depletion increases the mitotic index. Black-Right-Pointing-Pointer CNOT3 inhibits the expression of MAD1. Black-Right-Pointing-Pointer CNOT3 destabilizes the MAD1 mRNA. Black-Right-Pointing-Pointer MAD1 knockdown attenuates the CNOT3 depletion-induced mitotic arrest. -- Abstract: The stability of mRNA influences the dynamics of gene expression. The CCR4-NOT complex, the major deadenylase in mammalian cells, shortens the mRNA poly(A) tail and contributes to the destabilization of mRNAs. The CCR4-NOT complex plays pivotal roles in various physiological functions, including cell proliferation, apoptosis, and metabolism. Here, we show that CNOT3, a subunit of the CCR4-NOT complex, is involved in the regulation of the spindle assembly checkpoint, suggesting that the CCR4-NOT complex also plays a part in the regulation of mitosis. CNOT3 depletion increases the population of mitotic-arrested cells and specifically increases the expression of MAD1 mRNA and its protein product that plays a part in the spindle assembly checkpoint. We showed that CNOT3 depletion stabilizes the MAD1 mRNA, and that MAD1 knockdown attenuates the CNOT3 depletion-induced increase of the mitotic index. Basing on these observations, we propose that CNOT3 is involved in the regulation of the spindle assembly checkpoint through its ability to regulate the stability of MAD1 mRNA.

  16. A Novel Pathway that Coordinates Mitotic Exit with Spindle Position

    OpenAIRE

    Nelson, Scott A.; Cooper, John A.

    2007-01-01

    In budding yeast, the spindle position checkpoint (SPC) delays mitotic exit until the mitotic spindle moves into the neck between the mother and bud. This checkpoint works by inhibiting the mitotic exit network (MEN), a signaling cascade initiated and controlled by Tem1, a small GTPase. Tem1 is regulated by a putative guanine exchange factor, Lte1, but the function and regulation of Lte1 remains poorly understood. Here, we identify novel components of the checkpoint that operate upstream of L...

  17. Left-right symmetry breaking in mice by left-right dynein may occur via a biased chromatid segregation mechanism, without directly involving the Nodal gene

    Directory of Open Access Journals (Sweden)

    Stephan eSauer

    2012-11-01

    Full Text Available Ever since cloning the classic iv mutation identified the ‘left-right dynein’ (lrd gene in mice, most research on body laterality determination has focused on its function in motile cilia at the node embryonic organizer. This model is attractive, as it links chirality of cilia architecture to asymmetry development. However, lrd is also expressed in blastocysts and embryonic stem cells, where it was shown to bias the segregation of recombined sister chromatids away from each other in mitosis. These data suggested that lrd is part of a cellular mechanism that recognizes and selectively segregates sister chromatids based on their replication history: old ‘Watson’ vs. old ‘Crick’ strands. We previously proposed that the mouse left-right axis is established via an asymmetric cell division prior to/or during gastrulation. In this model, left-right dynein selectively segregates epigenetically differentiated sister chromatids harboring a hypothetical ‘left-right axis development 1’ (‘lra1’ gene during the left-right axis establishing cell division. Here, asymmetry development would be ultimately governed by the chirality of the cytoskeleton and the DNA molecule. Our model predicts that randomization of chromatid segregation in lrd mutants should produce embryos with 25% situs solitus, 25% situs inversus, and 50% embryonic death due to heterotaxia and isomerism. Here we confirmed this prediction by using two distinct lrd mutant alleles. Other than lrd, thus far Nodal gene is the most upstream function implicated in visceral organs laterality determination. We next tested whether the Nodal gene constitutes the lra1 gene hypothesized in the model by testing mutant’s effect on 50% embryonic lethality observed in lrd mutants. Since Nodal mutation did not suppress lethality, we conclude that Nodal is not equivalent to the lra1 gene. In summary, we describe the origin of 50% lethality in lrd mutant mice not yet explained by any other

  18. Novel insights into mitotic chromosome condensation

    Science.gov (United States)

    Piskadlo, Ewa; Oliveira, Raquel A.

    2016-01-01

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

  19. Molecular analysis of T-cell receptor beta genes in cutaneous T-cell lymphoma reveals Jbeta1 bias.

    Science.gov (United States)

    Morgan, Suzanne M; Hodges, Elizabeth; Mitchell, Tracey J; Harris, Susan; Whittaker, Sean J; Smith, John L

    2006-08-01

    Molecular characterization of T-cell receptor junctional region sequences in cutaneous T-cell lymphoma had not been previously reported. We have examined in detail the features of the T-cell receptor beta (TCRB) gene rearrangements in 20 individuals with well-defined stages of cutaneous T-cell lymphoma (CTCL) comprising 10 cases with early-stage mycosis fungoides (MF) and 10 cases with late-stage MF or Sezary syndrome. Using BIOMED-2 PCR primers, we detected a high frequency of clonally rearranged TCR gamma and TCRB genes (17/20 and 15/20 cases, respectively). We carried out sequencing analysis of each complete clonal variable (V)beta-diversity (D)beta-joining(J)beta fingerprint generated by PCR amplification, and determined the primary structure of the Vbeta-Dbeta-Jbeta junctional regions. We observed considerable diversity in the T-cell receptor Vbeta gene usage and complementarity-determining region 3 loops. Although we found that TCRB gene usage in CTCL and normal individuals share common features, our analysis also revealed preferential usage of Jbeta1 genes in all cases with advanced stages of disease.

  20. Analysis of phylogeny and codon usage bias and relationship of GC content, amino acid composition with expression of the structural nif genes.

    Science.gov (United States)

    Mondal, Sunil Kanti; Kundu, Sudip; Das, Rabindranath; Roy, Sujit

    2016-08-01

    Bacteria and archaea have evolved with the ability to fix atmospheric dinitrogen in the form of ammonia, catalyzed by the nitrogenase enzyme complex which comprises three structural genes nifK, nifD and nifH. The nifK and nifD encodes for the beta and alpha subunits, respectively, of component 1, while nifH encodes for component 2 of nitrogenase. Phylogeny based on nifDHK have indicated that Cyanobacteria is closer to Proteobacteria alpha and gamma but not supported by the tree based on 16SrRNA. The evolutionary ancestor for the different trees was also different. The GC1 and GC2% analysis showed more consistency than GC3% which appeared to below for Firmicutes, Cyanobacteria and Euarchaeota while highest in Proteobacteria beta and clearly showed the proportional effect on the codon usage with a few exceptions. Few genes from Firmicutes, Euryarchaeota, Proteobacteria alpha and delta were found under mutational pressure. These nif genes with low and high GC3% from different classes of organisms showed similar expected number of codons. Distribution of the genes and codons, based on codon usage demonstrated opposite pattern for different orientation of mirror plane when compared with each other. Overall our results provide a comprehensive analysis on the evolutionary relationship of the three structural nif genes, nifK, nifD and nifH, respectively, in the context of codon usage bias, GC content relationship and amino acid composition of the encoded proteins and exploration of crucial statistical method for the analysis of positive data with non-constant variance to identify the shape factors of codon adaptation index.

  1. Synonymous Codon Usage Bias and Overexpression of a Synthetic Gene Encoding Interferon α2b in Yeast

    Institute of Scientific and Technical Information of China (English)

    Bin FANG; Bu-feng LIANG; Guang-yuan HE

    2007-01-01

    To achieve higher level expression of Interferon α2b (IFN-α2b) in methylotrophic yeast (Pichia pastoris), a cDNA fragment coding for the mature IFN-α2b was designed and synthesized based on the synonymous codon bias of P. pastoris and optimized G+C content. The synthetic IFN-α2b was inserted into the secreted expression vector pPICZαA, and then integrated into P. pastoris GS115 genome by electroporation. Multi-copy integrants in the Mut+ recombinant P. pastoris strain were screened by high concentrations of Zeocin. 120 hours culturing allowed expression of the IFN-α2b transformant up to 810 mg/L as detected by SDS-PAGE and quantitative methods. In addition, Western blot analysis showed that the recombinant proteins had immunogenicity. The significant antiviral activity of the recombinant IFN-α2b protein was verified by WISH/ VSV system, which was 3.3×105 IU/mL.

  2. Cell death by mitotic catastrophe: a molecular definition

    NARCIS (Netherlands)

    Castedo, M.; Perfettini, J.-L.; Roumier, T.; Andreau, K.; Medema, R.H.; Kroemer, G.

    2004-01-01

    The current literature is devoid of a clearcut definition of mitotic catastrophe, a type of cell death that occurs during mitosis. Here, we propose that mitotic catastrophe results from a combination of deficient cell-cycle checkpoints (in particular the DNA structure checkpoints and the spindle ass

  3. Mitotic spindle assembly: May the force be with you

    NARCIS (Netherlands)

    Heesbeen, R.G.H.P. van

    2015-01-01

    The research described in this thesis is focused on multiple pathways required for assembly of a bipolar mitotic spindle. Proper assembly of a bipolar mitotic spindle is essential for the generation of stable kinetochore-microtubule attachments and correct segregation of the sister chromatids. Defec

  4. Random mitotic activities across human embryonic stem cell colonies.

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Q.; Duggan, R.; Dasa, S.; Li, F.; Chen, L. (Biosciences Division)

    2010-08-01

    A systemic and quantitative study was performed to examine whether different levels of mitotic activities, assessed by the percentage of S-phase cells at any given time point, existed at different physical regions of human embryonic stem (hES) cell colonies at 2, 4, 6 days after cell passaging. Mitotically active cells were identified by the positive incorporation of 5-bromo-2-deoxyuridine (BrdU) within their newly synthesized DNA. Our data indicated that mitotically active cells were often distributed as clusters randomly across the colonies within the examined growth period, presumably resulting from local deposition of newly divided cells. This latter notion was further demonstrated by the confined growth of enhanced green florescence protein (EGFP) expressing cells amongst non-GFP expressing cells. Furthermore, the overall percentage of mitotically active cells remained constantly at about 50% throughout the 6-day culture period, indicating mitotic activities of hES cell cultures were time-independent under current growth conditions.

  5. Species-Level Para- and Polyphyly in DNA Barcode Gene Trees: Strong Operational Bias in European Lepidoptera

    Science.gov (United States)

    Mutanen, Marko; Kivelä, Sami M.; Vos, Rutger A.; Doorenweerd, Camiel; Ratnasingham, Sujeevan; Hausmann, Axel; Huemer, Peter; Dincă, Vlad; van Nieukerken, Erik J.; Lopez-Vaamonde, Carlos; Vila, Roger; Aarvik, Leif; Decaëns, Thibaud; Efetov, Konstantin A.; Hebert, Paul D. N.; Johnsen, Arild; Karsholt, Ole; Pentinsaari, Mikko; Rougerie, Rodolphe; Segerer, Andreas; Tarmann, Gerhard; Zahiri, Reza; Godfray, H. Charles J.

    2016-01-01

    The proliferation of DNA data is revolutionizing all fields of systematic research. DNA barcode sequences, now available for millions of specimens and several hundred thousand species, are increasingly used in algorithmic species delimitations. This is complicated by occasional incongruences between species and gene genealogies, as indicated by situations where conspecific individuals do not form a monophyletic cluster in a gene tree. In two previous reviews, non-monophyly has been reported as being common in mitochondrial DNA gene trees. We developed a novel web service “Monophylizer” to detect non-monophyly in phylogenetic trees and used it to ascertain the incidence of species non-monophyly in COI (a.k.a. cox1) barcode sequence data from 4977 species and 41,583 specimens of European Lepidoptera, the largest data set of DNA barcodes analyzed from this regard. Particular attention was paid to accurate species identification to ensure data integrity. We investigated the effects of tree-building method, sampling effort, and other methodological issues, all of which can influence estimates of non-monophyly. We found a 12% incidence of non-monophyly, a value significantly lower than that observed in previous studies. Neighbor joining (NJ) and maximum likelihood (ML) methods yielded almost equal numbers of non-monophyletic species, but 24.1% of these cases of non-monophyly were only found by one of these methods. Non-monophyletic species tend to show either low genetic distances to their nearest neighbors or exceptionally high levels of intraspecific variability. Cases of polyphyly in COI trees arising as a result of deep intraspecific divergence are negligible, as the detected cases reflected misidentifications or methodological errors. Taking into consideration variation in sampling effort, we estimate that the true incidence of non-monophyly is ∼23%, but with operational factors still being included. Within the operational factors, we separately assessed the

  6. An in vivo model of mitotic cell death and Ras/MAPK signaling

    International Nuclear Information System (INIS)

    Full text: We have created the first and only existing tissue-model of mitotic cell death using the nematode C. elegans. We are able to measure radiation sensitivity in C. elegans by microscopically scoring the percentage of radiation-induced abnormal vulvae. We have found that these abnormalities are due to the death of the vulva cells after their third (and final) division, consistent with post-mitotic cell death. In C. elegans the Ras/MAPK signaling pathway is primarily responsible for the development of the hermaphrodite vulva, and is highly conserved to the mammalian Ras/MAPK pathway. We began by studying the effects of radiation on worm strains with mild loss-of-function (lof) mutations in components of the Ras/MAPK pathway. While the mutant strains that we studied have no abnormalities in normal vulva development, we found that all were radiosensitive, with increased radiation-induced vulval abnormalities as compared to wild-type worms. We therefore wanted to see if overexpression of the Ras/MAPK pathway would confer radioresistance in our system, so we irradiated a gain-of-function (gof) EGFR mutant worm strain. We found that this strain was radioresistant, with less radiation-induced vulval abnormalities than wild-type worms. We have concluded that the Ras/MAPK pathway protects against mitotic cell death in C. elegans. We wanted to better understand the downstream effectors of Ras/MAPK signaling that facilitate protection from mitotic cell death. Since mitotic cell death is due to DNA damage, we hypothesized that worm strains with mutations in the DNA damage response pathway should also be sensitive to mitotic cell death. We have begun analyzing worms with mutations in cell cycle checkpoint genes and DNA damage sensor genes, and have found that all of the strains tested thus far are highly radiosensitive. We plan to genetically cross gain-of-function Ras/MAPK mutants and loss-of-function checkpoint or damage response mutants, and determine the linearity of

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-03-10

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

  8. Lack of increases in methylation at three CpG-rich genomic loci in non-mitotic adult tissues during aging

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    Kanel Gary C

    2007-07-01

    Full Text Available Abstract Background Cell division occurs during normal human development and aging. Despite the likely importance of cell division to human pathology, it has been difficult to infer somatic cell mitotic ages (total numbers of divisions since the zygote because direct counting of lifetime numbers of divisions is currently impractical. Here we attempt to infer relative mitotic ages with a molecular clock hypothesis. Somatic genomes may record their mitotic ages because greater numbers of replication errors should accumulate after greater numbers of divisions. Mitotic ages will vary between cell types if they divide at different times and rates. Methods Age-related increases in DNA methylation at specific CpG sites (termed "epigenetic molecular clocks" have been previously observed in mitotic human epithelium like the intestines and endometrium. These CpG rich sequences or "tags" start unmethylated and potentially changes in methylation during development and aging represent replication errors. To help distinguish between mitotic versus time-associated changes, DNA methylation tag patterns at 8–20 CpGs within three different genes, two on autosomes and one on the X-chromosome were measured by bisulfite sequencing from heart, brain, kidney and liver of autopsies from 21 individuals of different ages. Results Levels of DNA methylation were significantly greater in adult compared to fetal or newborn tissues for two of the three examined tags. Consistent with the relative absence of cell division in these adult tissues, there were no significant increases in tag methylation after infancy. Conclusion Many somatic methylation changes at certain CpG rich regions or tags appear to represent replication errors because this methylation increases with chronological age in mitotic epithelium but not in non-mitotic organs. Tag methylation accumulates differently in different tissues, consistent with their expected genealogies and mitotic ages. Although

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

    International Nuclear Information System (INIS)

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

  10. SYNONYMOUS CONDON USAGE BIAS AND OVEREXPRESSION OF A SYNTHETIC xynB GENE FROM Aspergillus niger NL-1 IN Pichia pastoris

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    Fei Li, Shiyi Yang,

    2012-02-01

    Full Text Available To further improve the expression level of recombinant xylanase in Pichia pastoris, the xynB gene, encoding the mature peptide from Aspergillus niger NL-1, was designed and synthesized based on the synonymous condon bias of P. pastoris and optimized G+C content. 155 nucleotides were changed, and the GC content decreased from 57.7% to 43.6%. The synthetic xynB was inserted into the pPICZaA and then integrated into P. pastoris GS115. The activity of the recombinant xylanase reached 1414.7 U/mL, induced with 0.8% methanol after 14-day cultivation at a temperature of 28oC in shake flasks, which was 267% higher than that of the native gene. Furthermore, the maximum xylanase activity of 20424.2 U/mL was obtained by high-density fermentation in a 5-L fermenter, which was the highest xylanase expression in P. pastoris yet reported. The recombinant xylanase had its optimal activity at a pH of 5.0 and temperature of 50oC. The recombinant xylanase was stable over a pH range of 4.5 to 8.0. Thus, this report provides an industrial means to produce the recombinant xylanase in P. pastoris.

  11. Mitotic Catastrophe的研究进展%Progress in Mitotic Catastrophe

    Institute of Scientific and Technical Information of China (English)

    张博; 周平坤

    2007-01-01

    细胞死亡是多细胞生物生命过程中重要的生理或病理现象,可分为坏死和程序性细胞死亡,而后者根据死亡细胞的形态学和发生机制的不同又可分为凋亡、自吞噬和mitotic catastrophe,其中mitotic catastrophe是近年来才被揭示报道,是指细胞在有丝分裂过程中死亡的现象,是一种发生在细胞有丝分裂期由于异常的细胞分裂而导致的细胞死亡,它常常伴随着细胞有丝分裂检查点的异常和基因或纺锤体结构的损伤而发生.现对mitotic catastrophe及相关的调控机制进行综述.

  12. Cdc14 Early Anaphase Release, FEAR, Is Limited to the Nucleus and Dispensable for Efficient Mitotic Exit.

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    Christopher M Yellman

    Full Text Available Cdc14 phosphatase is a key regulator of exit from mitosis, acting primarily through antagonism of cyclin-dependent kinase, and is also thought to be important for meiosis. Cdc14 is released from its sequestration site in the nucleolus in two stages, first by the non-essential Cdc Fourteen Early Anaphase Release (FEAR pathway and later by the essential Mitotic Exit Network (MEN, which drives efficient export of Cdc14 to the cytoplasm. We find that Cdc14 is confined to the nucleus during early mitotic anaphase release, and during its meiosis I release. Proteins whose degradation is directed by Cdc14 as a requirement for mitotic exit (e.g. the B-type cyclin, Clb2, remain stable during mitotic FEAR, a result consistent with Cdc14 being restricted to the nucleus and not participating directly in mitotic exit. Cdc14 released by the FEAR pathway has been proposed to have a wide variety of activities, all of which are thought to promote passage through anaphase. Proposed functions of FEAR include stabilization of anaphase spindles, resolution of the rDNA to allow its segregation, and priming of the MEN so that mitotic exit can occur promptly and efficiently. We tested the model for FEAR functions using the FEAR-deficient mutation net1-6cdk. Our cytological observations indicate that, contrary to the current model, FEAR is fully dispensable for timely progression through a series of anaphase landmarks and mitotic exit, although it is required for timely rDNA segregation. The net1-6cdk mutation suppresses temperature-sensitive mutations in MEN genes, suggesting that rather than activating mitotic exit, FEAR either inhibits the MEN or has no direct effect upon it. One interpretation of this result is that FEAR delays MEN activation to ensure that rDNA segregation occurs before mitotic exit. Our findings clarify the distinction between FEAR and MEN-dependent Cdc14 activities and will help guide emerging quantitative models of this cell cycle transition.

  13. Over expression of a synthetic gene encoding interferon lambda using relative synonymous codon usage bias in Escherichia coli.

    Science.gov (United States)

    Akhtar, Hashaam; Akhtar, Samar; Jan, Syed Umer; Khan, Azka; Zaidi, Najam us Sahar Sadaf; Qadri, Ishtiaq

    2013-11-01

    Interferon Lambda (IFN-λ) is a type III interferon which belongs to a novel family of cytokines and possesses antiviral and antitumor properties. It is unique in its own class of cytokines; because of the specificity towards its heterodimer receptors and its structural similarities with cytokines of other classes. This renders IFN-λ a better choice for the treatment against many diseases including viral hepatitis and human coronavirus (HCoV-EMC). The present study describes a computational approach known as relative synonymous codon usage (RSCU); used to enhance the expression of IFN-λ protein in a eukaryotic expression system. Manually designed and commercially synthesized IFN-λ gene was cloned into pET-22b expression plasmid under the control of inducible T7-lac promoter. Maximum levels of IFN-λ expression was observed with 0.4 mM IPTG in transformed E. coli incubated for 4 hours in LB medium. Higher concentrations of IPTG had no or negative effect on the expression of IFN-λ. This synthetically over expressed IFN-λ can be tested as a targeted treatment option for viral hepatitis after purification. PMID:24191324

  14. Male- and Female-Biased Gene Expression of Olfactory-Related Genes in the Antennae of Asian Corn Borer, Ostrinia furnacalis (Guenée) (Lepidoptera: Crambidae)

    OpenAIRE

    Zhang, Tiantao; Coates, Brad S.; Ge, Xing; Bai, Shuxiong; He, Kanglai; Wang, Zhenying

    2015-01-01

    The Asian corn borer (ACB), Ostrinia furnacalis (Guenée), is a destructive pest insect of cultivated corn crops, for which antennal-expressed receptors are important to detect olfactory cues for mate attraction and oviposition. Few olfactory related genes were reported in ACB, so we sequenced and characterized the transcriptome of male and female O. furnacalis antennae. Non-normalized male and female O. furnacalis antennal cDNA libraries were sequenced on the Illumina HiSeq 2000 and assembled...

  15. Biased Allostery.

    Science.gov (United States)

    Edelstein, Stuart J; Changeux, Jean-Pierre

    2016-09-01

    G-protein-coupled receptors (GPCRs) constitute a large group of integral membrane proteins that transduce extracellular signals from a wide range of agonists into targeted intracellular responses. Although the responses can vary depending on the category of G-proteins activated by a particular receptor, responses were also found to be triggered by interactions of the receptor with β-arrestins. It was subsequently discovered that for the same receptor molecule (e.g., the β-adrenergic receptor), some agonists have a propensity to specifically favor responses by G-proteins, others by β-arrestins, as has now been extensively studied. This feature of the GPCR system is known as biased agonism and is subject to various interpretations, including agonist-induced conformational change versus selective stabilization of preexisting active conformations. Here, we explore a complete allosteric framework for biased agonism based on alternative preexisting conformations that bind more strongly, but nonexclusively, either G-proteins or β-arrestins. The framework incorporates reciprocal effects among all interacting molecules. As a result, G-proteins and β-arrestins are in steric competition for binding to the cytoplasmic surface of either the G-protein-favoring or β-arrestin-favoring GPCR conformation. Moreover, through linkage relations, the strength of the interactions of G-proteins or β-arrestins with the corresponding active conformation potentiates the apparent affinity for the agonist, effectively equating these two proteins to allosteric modulators. The balance between response alternatives can also be influenced by the physiological concentrations of either G-proteins or β-arrestins, as well as by phosphorylation or interactions with positive or negative allosteric modulators. The nature of the interactions in the simulations presented suggests novel experimental tests to distinguish more fully among alternative mechanisms. PMID:27602718

  16. T cell receptor Vβ gene bias in rheumatoid arthritis%类风湿关节炎T细胞受体Vβ基因的表达

    Institute of Scientific and Technical Information of China (English)

    张卓莉; 董怡; 张国柱

    2002-01-01

    目的通过对T细胞受体(TCR)的表达进行研究,探讨类风湿关节炎的发病机制.方法应用半定量的逆转录多聚酶链反应(RT-PCR)分析类风湿关节炎、骨关节炎、截肢病人滑膜和外周血中T细胞受体Vβ基因(TCR Vβ1-TCR Vβ24)的使用情况,经基因扫描分析确定其表达水平.结果类风湿关节炎、骨关节炎及截肢病人的滑膜组织与外周血表达绝大多数的Vβ基因;类风湿关节炎病人滑膜组织中Vβ基因的使用呈现更明显的不均衡状态;Vβ6、 Vβ17与Vβ22为优势亚群.其中以Vβ17增高最为显著.结论类风湿关节炎病人滑膜组织中Vβ基因的表达无限制性,但是存在明显的不均衡性.某些特定Vβ基因的选择性扩增支持类风湿关节炎为抗原或超抗原驱动的免疫过程.%Objectives To explore the pathogenesis of rheumatoid arthritis (RA) by studying the expression of T cell receptors (TCRs).Methods T cell receptor Vβ (TCR Vβ) gene usage and expression were analyzed from synovial membrane and peripheral blood of 8 RA patients, 2 osteoarthritis patients and 2 accident amputees. The complementary determining region 3 (CDR3) of 25 TCR Vβ subfamily genes in unselected T cell populations were amplified semi-quantitatively by reverse transcription-polymerase chain reaction (RT-PCR). The products were further studied by genescan for frequency of Vβ usage.Results The numbers of Vβ subfamilies expressed by T cells from RA peripheral blood and synovial membrane were not significantly restricted. More importantly, biasedgene expression in RA synovium was observed and Vβ6, Vβ17, and Vβ22 genes were the predominant subfamilies. It was noteworthy that the expression of Vβ17 in RA synovium was significantly increased. Conclusion Our data were consistent with the hypothesis that several antigen or superantigen-driven processes may be involved in the pathogenesis of RA.

  17. Population genetic structure of the African elephant in Uganda based on variation at mitochondrial and nuclear loci: evidence for male-biased gene flow.

    Science.gov (United States)

    Nyakaana, S; Arctander, P

    1999-07-01

    A drastic decline has occurred in the size of the Uganda elephant population in the last 40 years, exacerbated by two main factors; an increase in the size of the human population and poaching for ivory. One of the attendant consequences of such a decline is a reduction in the amount of genetic diversity in the surviving populations due to increased effects of random genetic drift. Information about the amount of genetic variation within and between the remaining populations is vital for their future conservation and management. The genetic structure of the African elephant in Uganda was examined using nucleotide variation of mitochondrial control region sequences and four nuclear microsatellite loci in 72 individuals from three localities. Eleven mitochondrial DNA (mtDNA) haplotypes were observed, nine of which were geographically localized. We found significant genetic differentiation between the three populations at the mitochondrial locus while three out of the four microsatellite loci differentiated KV and QE, one locus differentiated KV and MF and no loci differentiated MF and QE. Expected heterozygosity at the four loci varied between 0.51 and 0.84 while nucleotide diversity at the mitochondrial locus was 1.4%. Incongruent patterns of genetic variation within and between populations were revealed by the two genetic systems, and we have explained these in terms of the differences in the effective population sizes of the two genomes and male-biased gene flow between populations.

  18. Mitotic Diversity in Homeostatic Human Interfollicular Epidermis

    Directory of Open Access Journals (Sweden)

    Katharina Nöske

    2016-01-01

    Full Text Available Despite decades of skin research, regulation of proliferation and homeostasis in human epidermis is still insufficiently understood. To address the role of mitoses in tissue regulation, we utilized human long-term skin equivalents and systematically assessed mitoses during early epidermal development and long-term epidermal regeneration. We now demonstrate four different orientations: (1 horizontal, i.e., parallel to the basement membrane (BM and suggestive of symmetric divisions; (2 oblique with an angle of 45°–70°; or (3 perpendicular, suggestive of asymmetric division. In addition, we demonstrate a fourth substantial fraction of suprabasal mitoses, many of which are committed to differentiation (Keratin K10-positive. As verified also for normal human skin, this spatial mitotic organization is part of the regulatory program of human epidermal tissue homeostasis. As a potential marker for asymmetric division, we investigated for Numb and found that it was evenly spread in almost all undifferentiated keratinocytes, but indeed asymmetrically distributed in some mitoses and particularly frequent under differentiation-repressing low-calcium conditions. Numb deletion (stable knockdown by CRISPR/Cas9, however, did not affect proliferation, neither in a three-day follow up study by life cell imaging nor during a 14-day culture period, suggesting that Numb is not essential for the general control of keratinocyte division.

  19. Timeless links replication termination to mitotic kinase activation.

    Science.gov (United States)

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

    2011-05-06

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

  20. Timeless links replication termination to mitotic kinase activation.

    Directory of Open Access Journals (Sweden)

    Jayaraju Dheekollu

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

  1. SMC1B is present in mammalian somatic cells and interacts with mitotic cohesin proteins.

    Science.gov (United States)

    Mannini, Linda; Cucco, Francesco; Quarantotti, Valentina; Amato, Clelia; Tinti, Mara; Tana, Luigi; Frattini, Annalisa; Delia, Domenico; Krantz, Ian D; Jessberger, Rolf; Musio, Antonio

    2015-01-01

    Cohesin is an evolutionarily conserved protein complex that plays a role in many biological processes: it ensures faithful chromosome segregation, regulates gene expression and preserves genome stability. In mammalian cells, the mitotic cohesin complex consists of two structural maintenance of chromosome proteins, SMC1A and SMC3, the kleisin protein RAD21 and a fourth subunit either STAG1 or STAG2. Meiotic paralogs in mammals were reported for SMC1A, RAD21 and STAG1/STAG2 and are called SMC1B, REC8 and STAG3 respectively. It is believed that SMC1B is only a meiotic-specific cohesin member, required for sister chromatid pairing and for preventing telomere shortening. Here we show that SMC1B is also expressed in somatic mammalian cells and is a member of a mitotic cohesin complex. In addition, SMC1B safeguards genome stability following irradiation whereas its ablation has no effect on chromosome segregation. Finally, unexpectedly SMC1B depletion impairs gene transcription, particularly at genes mapping to clusters such as HOX and PCDHB. Genome-wide analyses show that cluster genes changing in expression are enriched for cohesin-SMC1B binding.

  2. A mitotic recombination map proximal to the APC locus on chromosome 5q and assessment of influences on colorectal cancer risk

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    Clark Susan

    2009-06-01

    Full Text Available Abstract Background Mitotic recombination is important for inactivating tumour suppressor genes by copy-neutral loss of heterozygosity (LOH. Although meiotic recombination maps are plentiful, little is known about mitotic recombination. The APC gene (chr5q21 is mutated in most colorectal tumours and its usual mode of LOH is mitotic recombination. Methods We mapped mitotic recombination boundaries ("breakpoints" between the centromere (~50 Mb and APC (~112 Mb in early colorectal tumours. Results Breakpoints were non-random, with the highest frequency between 65 Mb and 75 Mb, close to a low copy number repeat region (68–71 Mb. There were, surprisingly, few breakpoints close to APC, contrary to expectations were there constraints on tumorigenesis caused by uncovering recessive lethal alleles or if mitotic recombination were mechanistically favoured by a longer residual chromosome arm. The locations of mitotic and meiotic recombination breakpoints were correlated, suggesting that the two types of recombination are influenced by similar processes, whether mutational or selective in origin. Breakpoints were also associated with higher local G+C content. The recombination and gain/deletion breakpoint maps on 5q were not, however, associated, perhaps owing to selective constraints on APC dosage in early colorectal tumours. Since polymorphisms within the region of frequent mitotic recombination on 5q might influence the frequency of LOH, we tested the 68–71 Mb low copy number repeat and nearby tagSNPs, but no associations with colorectal cancer risk were found. Conclusion LOH on 5q is non-random, but local factors do not greatly influence the rate of LOH at APC or explain inter differential susceptibility to colorectal tumours.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-08-01

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

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1981-09-01

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

  6. "Artificial mitotic spindle" generated by dielectrophoresis and protein micropatterning supports bidirectional transport of kinesin-coated beads.

    Science.gov (United States)

    Uppalapati, Maruti; Huang, Ying-Ming; Aravamuthan, Vidhya; Jackson, Thomas N; Hancock, William O

    2011-01-01

    The mitotic spindle is a dynamic assembly of microtubules and microtubule-associated proteins that controls the directed movement of chromosomes during cell division. Because proper segregation of the duplicated genome requires that each daughter cell receives precisely one copy of each chromosome, numerous overlapping mechanisms have evolved to ensure that every chromosome is transported to the cell equator during metaphase. However, due to the inherent redundancy in this system, cellular studies using gene knockdowns or small molecule inhibitors have an inherent limit in defining the sufficiency of precise molecular mechanisms as well as quantifying aspects of their mechanical performance. Thus, there exists a need for novel experimental approaches that reconstitute important aspects of the mitotic spindle in vitro. Here, we show that by microfabricating Cr electrodes on quartz substrates and micropatterning proteins on the electrode surfaces, AC electric fields can be used to assemble opposed bundles of aligned and uniformly oriented microtubules as found in the mitotic spindle. By immobilizing microtubule ends on each electrode, analogous to anchoring at centrosomes, solutions of motor or microtubule binding proteins can be introduced and their resulting dynamics analyzed. Using this "artificial mitotic spindle" we show that beads functionalized with plus-end kinesin motors move in an oscillatory manner analogous to the movements of chromosomes and severed chromosome arms during metaphase. Hence, features of directional instability, an established characteristic of metaphase chromosome dynamics, can be reconstituted in vitro using a pair of uniformly oriented microtubule bundles and a plus-end kinesin functionalized bead.

  7. Molecular origin of mitotic aneuploidies in preimplantation embryos.

    Science.gov (United States)

    Mantikou, Eleni; Wong, Kai Mee; Repping, Sjoerd; Mastenbroek, Sebastiaan

    2012-12-01

    Mitotic errors are common in human preimplantation embryos. The occurrence of mitotic errors is highest during the first three cleavages after fertilization and as a result about three quarters of human preimplantation embryos show aneuploidies and are chromosomally mosaic at day three of development. The origin of these preimplantation mitotic aneuploidies and the molecular mechanisms involved are being discussed in this review. At later developmental stages the mitotic aneuploidy rate is lower. Mechanisms such as cell arrest, apoptosis, active correction of the aneuploidies and preferential allocation of the aneuploid cells to the extra-embryonic tissues could underlie this lower rate. Understanding the mechanisms that cause mitotic aneuploidies in human preimplantation embryos and the way human preimplantation embryos deal with these aneuploidies might lead to ways to limit the occurrence of aneuploidies, in order to ultimately increase the quality of embryos and with that the likelihood of a successful pregnancy in IVF/ICSI. This article is part of a Special Issue entitled: Molecular Genetics of Human Reproductive Failure. PMID:22771499

  8. Robust mitotic entry is ensured by a latching switch

    Directory of Open Access Journals (Sweden)

    Chloe Tuck

    2013-07-01

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

  9. The Emerging Nexus of Active DNA Demethylation and Mitochondrial Oxidative Metabolism in Post-Mitotic Neurons

    Directory of Open Access Journals (Sweden)

    Huan Meng

    2014-12-01

    Full Text Available The variable patterns of DNA methylation in mammals have been linked to a number of physiological processes, including normal embryonic development and disease pathogenesis. Active removal of DNA methylation, which potentially regulates neuronal gene expression both globally and gene specifically, has been recently implicated in neuronal plasticity, learning and memory processes. Model pathways of active DNA demethylation involve ten-eleven translocation (TET methylcytosine dioxygenases that are dependent on oxidative metabolites. In addition, reactive oxygen species (ROS and oxidizing agents generate oxidative modifications of DNA bases that can be removed by base excision repair proteins. These potentially link the two processes of active DNA demethylation and mitochondrial oxidative metabolism in post-mitotic neurons. We review the current biochemical understanding of the DNA demethylation process and discuss its potential interaction with oxidative metabolism. We then summarise the emerging roles of both processes and their interaction in neural plasticity and memory formation and the pathophysiology of neurodegeneration. Finally, possible therapeutic approaches for neurodegenerative diseases are proposed, including reprogramming therapy by global DNA demethylation and mitohormesis therapy for locus-specific DNA demethylation in post-mitotic neurons.

  10. The effects of X-rays on the mitotic activity of mouse epidermis

    Energy Technology Data Exchange (ETDEWEB)

    Knowlton, N.P. Jr.; Hempelmann, L.H.; Hoffman, J.G.

    1949-04-19

    This report describes a simplified technique of obtaining the mitotic index of mouse skin and indicates the surprising sensitivity of the mitotic activity of mouse epithelium to the effects of x-rays.

  11. Action study of mumio preparation on mitotic index by autoradiography way

    International Nuclear Information System (INIS)

    In this chapter author made conclusion that leading of mumio preparation raise the mitotic activity and promote of rapid passing by cells mitotic cycle that lead to rapid partition and raising of quantity cells in hemopoietic organs

  12. Awareness Reduces Racial Bias

    OpenAIRE

    Pope, Devin G.; Price, Joseph; Wolfers, Justin

    2014-01-01

    Can raising awareness of racial bias subsequently reduce that bias? We address this question by exploiting the widespread media attention highlighting racial bias among professional basketball referees that occurred in May 2007 following the release of an academic study. Using new data, we confirm that racial bias persisted in the years after the study's original sample, but prior to the media coverage. Subsequent to the media coverage though, the bias completely disappeared. We examine poten...

  13. SBDS expression and localization at the mitotic spindle in human myeloid progenitors.

    Directory of Open Access Journals (Sweden)

    Claudia Orelio

    Full Text Available BACKGROUND: Shwachman-Diamond Syndrome (SDS is a hereditary disease caused by mutations in the SBDS gene. SDS is clinically characterized by pancreatic insufficiency, skeletal abnormalities and bone marrow dysfunction. The hematologic abnormalities include neutropenia, neutrophil chemotaxis defects, and an increased risk of developing Acute Myeloid Leukemia (AML. Although several studies have suggested that SBDS as a protein plays a role in ribosome processing/maturation, its impact on human neutrophil development and function remains to be clarified. METHODOLOGY/PRINCIPAL FINDINGS: We observed that SBDS RNA and protein are expressed in the human myeloid leukemia PLB-985 cell line and in human hematopoietic progenitor cells by quantitative RT-PCR and Western blot analysis. SBDS expression is downregulated during neutrophil differentiation. Additionally, we observed that the differentiation and proliferation capacity of SDS-patient bone marrow hematopoietic progenitor cells in a liquid differentiation system was reduced as compared to control cultures. Immunofluorescence analysis showed that SBDS co-localizes with the mitotic spindle and in vitro binding studies reveal a direct interaction of SBDS with microtubules. In interphase cells a perinuclear enrichment of SBDS protein which co-localized with the microtubule organizing center (MTOC was observed. Also, we observed that transiently expressed SDS patient-derived SBDS-K62 or SBDS-C84 mutant proteins could co-localize with the MTOC and mitotic spindle. CONCLUSIONS/SIGNIFICANCE: SBDS co-localizes with the mitotic spindle, suggesting a role for SBDS in the cell division process, which corresponds to the decreased proliferation capacity of SDS-patient bone marrow CD34(+ hematopoietic progenitor cells in our culture system and also to the neutropenia in SDS patients. A role in chromosome missegregation has not been clarified, since similar spatial and time-dependent localization is observed when

  14. Arabidopsis COPPER MODIFIED RESISTANCE1/PATRONUS1 is essential for growth adaptation to stress and required for mitotic onset control.

    Science.gov (United States)

    Juraniec, Michal; Heyman, Jefri; Schubert, Veit; Salis, Pietrino; De Veylder, Lieven; Verbruggen, Nathalie

    2016-01-01

    The mitotic checkpoint (MC) guards faithful sister chromatid segregation by monitoring the attachment of spindle microtubules to the kinetochores. When chromosome attachment errors are detected, MC delays the metaphase-to-anaphase transition through the inhibition of the anaphase-promoting complex/cyclosome (APC/C) ubiquitin ligase. In contrast to yeast and mammals, our knowledge on the proteins involved in MC in plants is scarce. Transient synchronization of root tips as well as promoter-reporter gene fusions were performed to analyze temporal and spatial expression of COPPER MODIFIED RESISTANCE1/PATRONUS1 (CMR1/PANS1) in developing Arabidopsis thaliana seedlings. Functional analysis of the gene was carried out, including CYCB1;2 stability in CMR1/PANS1 knockout and overexpressor background as well as metaphase-anaphase chromosome status. CMR1/PANS1 is transcriptionally active during M phase. Its deficiency provokes premature cell cycle exit and in consequence a rapid consumption of the number of meristematic cells in particular under stress conditions that are known to affect spindle microtubules. Root growth impairment is correlated with a failure to delay the onset of anaphase, resulting in anaphase bridges and chromosome missegregation. CMR1/PANS1 overexpression stabilizes the mitotic CYCB1;2 protein. Likely, CMR1/PANS1 coordinates mitotic cell cycle progression by acting as an APC/C inhibitor and plays a key role in growth adaptation to stress.

  15. Tumor environmental factors glucose deprivation and lactic acidosis induce mitotic chromosomal instability--an implication in aneuploid human tumors.

    Directory of Open Access Journals (Sweden)

    Chunyan Dai

    Full Text Available Mitotic chromosomal instability (CIN plays important roles in tumor progression, but what causes CIN is incompletely understood. In general, tumor CIN arises from abnormal mitosis, which is caused by either intrinsic or extrinsic factors. While intrinsic factors such as mitotic checkpoint genes have been intensively studied, the impact of tumor microenvironmental factors on tumor CIN is largely unknown. We investigate if glucose deprivation and lactic acidosis--two tumor microenvironmental factors--could induce cancer cell CIN. We show that glucose deprivation with lactic acidosis significantly increases CIN in 4T1, MCF-7 and HCT116 scored by micronuclei, or aneuploidy, or abnormal mitosis, potentially via damaging DNA, up-regulating mitotic checkpoint genes, and/or amplifying centrosome. Of note, the feature of CIN induced by glucose deprivation with lactic acidosis is similar to that of aneuploid human tumors. We conclude that tumor environmental factors glucose deprivation and lactic acidosis can induce tumor CIN and propose that they are potentially responsible for human tumor aneuploidy.

  16. BIFURCATION ANALYSIS OF A MITOTIC MODEL OF FROG EGGS

    Institute of Scientific and Technical Information of China (English)

    吕金虎; 张子范; 张锁春

    2003-01-01

    The mitotic model of frog eggs established by Borisuk and Tyson is qualitatively analyzed. The existence and stability of its steady states are further discussed. Furthermore, the bifurcation of above model is further investigated by using theoretical analysis and numerical simulations. At the same time, the numerical results of Tyson are verified by theoretical analysis.

  17. Rab11 endosomes contribute to mitotic spindle organization and orientation.

    Science.gov (United States)

    Hehnly, Heidi; Doxsey, Stephen

    2014-03-10

    During interphase, Rab11-GTPase-containing endosomes recycle endocytic cargo. However, little is known about Rab11 endosomes in mitosis. Here, we show that Rab11 localizes to the mitotic spindle and regulates dynein-dependent endosome localization at poles. We found that mitotic recycling endosomes bind γ-TuRC components and associate with tubulin in vitro. Rab11 depletion or dominant-negative Rab11 expression disrupts astral microtubules, delays mitosis, and redistributes spindle pole proteins. Reciprocally, constitutively active Rab11 increases astral microtubules, restores γ-tubulin spindle pole localization, and generates robust spindles. This suggests a role for Rab11 activity in spindle pole maturation during mitosis. Rab11 depletion causes misorientation of the mitotic spindle and the plane of cell division. These findings suggest a molecular mechanism for the organization of astral microtubules and the mitotic spindle through Rab11-dependent control of spindle pole assembly and function. We propose that Rab11 and its associated endosomes cocontribute to these processes through retrograde transport to poles by dynein. PMID:24561039

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

    Science.gov (United States)

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

    2016-01-01

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

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

    Science.gov (United States)

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

    2012-09-17

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

  20. File list: ALL.Emb.10.AllAg.Mitotic_cycle_12 [Chip-atlas[Archive

    Lifescience Database Archive (English)

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    Lifescience Database Archive (English)

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    Lifescience Database Archive (English)

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

    Directory of Open Access Journals (Sweden)

    Elena Rosu

    2006-08-01

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

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

    Science.gov (United States)

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

    2015-02-01

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

  20. Mechanism of APC/CCDC20 activation by mitotic phosphorylation.

    Science.gov (United States)

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

    2016-05-10

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

  1. Paclitaxel-induced microtubule stabilization causes mitotic block and apoptotic-like cell death in a paclitaxel-sensitive strain of Saccharomyces cerevisiae

    OpenAIRE

    Foland, Travis B.; Dentler, William L.; SUPRENANT, KATHY A.; Gupta, Mohan L.; Himes, Richard H.

    2005-01-01

    Wild-type Saccharomyces cerevisiae tubulin does not bind the anti-mitotic microtubule stabilizing agent paclitaxel. Previously, we introduced mutations into the S. cerevisiae gene for β-tubulin that imparted paclitaxel binding to the protein, but the mutant strain was not sensitive to paclitaxel and other microtubule-stabilizing agents, due to the multiple ABC transporters in the membranes of budding yeast. Here, we introduced the mutated β-tubulin gene into a S. cerevisiae strain with dimini...

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

    Science.gov (United States)

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

    2011-06-01

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

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

    Science.gov (United States)

    Craig, R; Norbury, C

    1998-12-18

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

  4. Mitotic Origins of Chromosomal Instability in Colorectal Cancer

    OpenAIRE

    Dalton, W. Brian; Yang, Vincent W.

    2007-01-01

    Mitosis is a crucial part of the cell cycle. A successful mitosis requires the proper execution of many complex cellular behaviors. Thus, there are many points at which mitosis may be disrupted. In cancer cells, chronic disruption of mitosis can lead to unequal segregation of chromosomes, a phenomenon known as chromosomal instability. A majority of colorectal tumors suffer from this instability, and recent studies have begun to reveal the specific ways in which mitotic defects promote chromos...

  5. A Genetic Map of DICTYOSTELIUM DISCOIDEUM Based on Mitotic Recombination

    OpenAIRE

    Welker, Dennis L.; Williams, Keith L.

    1982-01-01

    A genetic map of the cellular slime mold Dictyostelium discoideum is presented in which 42 loci are ordered on five of the seven linkage groups. Although most of the loci were ordered using standing mitotic crossing-over techniques in which recessive selective markers were employed, use was also made of unselected recombined haploid strains. Consistent with cytological studies in which the chromosomes appear to be acrocentric, only a single arm has been found for each of the five linkage grou...

  6. Mitotic exit: Determining the PP2A dephosphorylation program.

    Science.gov (United States)

    Pereira, Gislene; Schiebel, Elmar

    2016-08-29

    In mitotic exit, proteins that were highly phosphorylated are sequentially targeted by the phosphatase PP2A-B55, but what underlies substrate selection is unclear. In this issue, Cundell et al. (2016. J. Cell Biol http://dx.doi.org/10.1083/jcb.201606033) identify the determinants of PP2A-B55's dephosphorylation program, thereby influencing spindle disassembly, nuclear envelope reformation, and cytokinesis. PMID:27551057

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

    Science.gov (United States)

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

    2016-08-01

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

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

    Science.gov (United States)

    Kharasch, J A

    1987-06-01

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

  9. Daxx regulates mitotic progression and prostate cancer predisposition.

    Science.gov (United States)

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

    2013-04-01

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

  10. SUMOylation inhibits FOXM1 activity and delays mitotic transition.

    Science.gov (United States)

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

    2014-08-21

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

  11. Analysis of the ORF1a Gene Codon Bias Disparity in Different PRRSV Strains%不同PRRSV毒株间ORF1a基因密码子偏爱性差异分析

    Institute of Scientific and Technical Information of China (English)

    招丽婵; 邓雨修; 王东东; 苏润环; 李春梅; 徐贵娟; 宋延华

    2009-01-01

    Cluster analysis of the codon usage bias of 29 PRRSV ORF1a gene was performed by using bioinformatics software including Codon W, EMBOSS, CIMMine, ClustalX and TreeView. Correlation analysis for CAI, CBI, Fop, Nc, Length, GC3s and GC content showed that there existed disparity in ORF1a gene codon usage bias of different PRRSV strains, especially when comparing strain Lelystad, LV4.2.1, VR-2332, RespPRRS MLV with highly pathogenic PRRSV ones isolated from China. Cluster analysis of the ORF1a gene condon usage frequency demonstrated that the highly pathogenic PRRSV strains were more closely related to each other than to CC-1, NVSL-97-7895, CH-1a, RespPRRS MLV, LV4.2.1 and Lelystad virus strains, which was compatible to the amino acid sequences phylogenetic analysis result. In summary, it can be concluded that the codon usage bias of the PRRSV ORF1a gene was highly correlated with the virus genetic diversity of PRRSV strains.%运用Codon W、ClustalX、TreeView软件及EMBOSS(The European Molecular Biology Open Software Suite)、CIMMiner在线分析软件对选取的29株PRRSV ORF1a基因进行密码子偏爱性聚类分析.CAI、CBI、Fop、Nc、GC3s和GC含量、基因长度等相关性分析显示PRRSV各毒株编码的ORF1a基因密码子偏爱性各有差异,其中Lelystad virus、LV4.2.1、VR-2332、RespPRRS MLV与国内分离的高致病性PRRSV变异株之间差异较大.密码子使用概率聚类分析表明CC-1、NVSL-97-7895、CH-1a、BespPRRS MLV、LV4.2.1、Lelystad virus 与高致病性PRRSV变异株距离较远,而国内分离株相互间的聚类距离则较接近,此结果与基于氨基酸序列比对构建的系统进化树图谱基本一致.由此可见,PRRSV病毒ORF1a基因密码子使用偏爱性的差别与病毒的遗传多样性密切相关.

  12. APC/C-Cdh1-dependent anaphase and telophase progression during mitotic slippage

    Directory of Open Access Journals (Sweden)

    Toda Kazuhiro

    2012-02-01

    Full Text Available Abstract Background The spindle assembly checkpoint (SAC inhibits anaphase progression in the presence of insufficient kinetochore-microtubule attachments, but cells can eventually override mitotic arrest by a process known as mitotic slippage or adaptation. This is a problem for cancer chemotherapy using microtubule poisons. Results Here we describe mitotic slippage in yeast bub2Δ mutant cells that are defective in the repression of precocious telophase onset (mitotic exit. Precocious activation of anaphase promoting complex/cyclosome (APC/C-Cdh1 caused mitotic slippage in the presence of nocodazole, while the SAC was still active. APC/C-Cdh1, but not APC/C-Cdc20, triggered anaphase progression (securin degradation, separase-mediated cohesin cleavage, sister-chromatid separation and chromosome missegregation, in addition to telophase onset (mitotic exit, during mitotic slippage. This demonstrates that an inhibitory system not only of APC/C-Cdc20 but also of APC/C-Cdh1 is critical for accurate chromosome segregation in the presence of insufficient kinetochore-microtubule attachments. Conclusions The sequential activation of APC/C-Cdc20 to APC/C-Cdh1 during mitosis is central to accurate mitosis. Precocious activation of APC/C-Cdh1 in metaphase (pre-anaphase causes mitotic slippage in SAC-activated cells. For the prevention of mitotic slippage, concomitant inhibition of APC/C-Cdh1 may be effective for tumor therapy with mitotic spindle poisons in humans.

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

    Science.gov (United States)

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

    2015-01-01

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

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

    Science.gov (United States)

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

    2015-01-01

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

  15. PUL21a-Cyclin A2 interaction is required to protect human cytomegalovirus-infected cells from the deleterious consequences of mitotic entry.

    Directory of Open Access Journals (Sweden)

    Martin Eifler

    2014-10-01

    Full Text Available Entry into mitosis is accompanied by dramatic changes in cellular architecture, metabolism and gene expression. Many viruses have evolved cell cycle arrest strategies to prevent mitotic entry, presumably to ensure sustained, uninterrupted viral replication. Here we show for human cytomegalovirus (HCMV what happens if the viral cell cycle arrest mechanism is disabled and cells engaged in viral replication enter into unscheduled mitosis. We made use of an HCMV mutant that, due to a defective Cyclin A2 binding motif in its UL21a gene product (pUL21a, has lost its ability to down-regulate Cyclin A2 and, therefore, to arrest cells at the G1/S transition. Cyclin A2 up-regulation in infected cells not only triggered the onset of cellular DNA synthesis, but also promoted the accumulation and nuclear translocation of Cyclin B1-CDK1, premature chromatin condensation and mitotic entry. The infected cells were able to enter metaphase as shown by nuclear lamina disassembly and, often irregular, metaphase spindle formation. However, anaphase onset was blocked by the still intact anaphase promoting complex/cyclosome (APC/C inhibitory function of pUL21a. Remarkably, the essential viral IE2, but not the related chromosome-associated IE1 protein, disappeared upon mitotic entry, suggesting an inherent instability of IE2 under mitotic conditions. Viral DNA synthesis was impaired in mitosis, as demonstrated by the abnormal morphology and strongly reduced BrdU incorporation rates of viral replication compartments. The prolonged metaphase arrest in infected cells coincided with precocious sister chromatid separation and progressive fragmentation of the chromosomal material. We conclude that the Cyclin A2-binding function of pUL21a contributes to the maintenance of a cell cycle state conducive for the completion of the HCMV replication cycle. Unscheduled mitotic entry during the course of the HCMV replication has fatal consequences, leading to abortive infection and

  16. On commercial media bias

    OpenAIRE

    Germano, Fabrizio

    2008-01-01

    Within the spokes model of Chen and Riordan (2007) that allows for non-localized competition among arbitrary numbers of media outlets, we quantify the effect of concentration of ownership on quality and bias of media content. A main result shows that too few commercial outlets, or better, too few separate owners of commercial outlets can lead to substantial bias in equilibrium. Increasing the number of outlets (commercial and non-commercial) tends to bring down this bias; but the strong...

  17. Bias aware Kalman filters

    DEFF Research Database (Denmark)

    Drecourt, J.-P.; Madsen, H.; Rosbjerg, Dan

    2006-01-01

    This paper reviews two different approaches that have been proposed to tackle the problems of model bias with the Kalman filter: the use of a colored noise model and the implementation of a separate bias filter. Both filters are implemented with and without feedback of the bias into the model state...... are illustrated on a simple one-dimensional groundwater problem. The results show that the presented filters outperform the standard Kalman filter and that the implementations with bias feedback work in more general conditions than the implementations without feedback. 2005 Elsevier Ltd. All rights reserved....

  18. Interpretation biases in paranoia.

    Science.gov (United States)

    Savulich, George; Freeman, Daniel; Shergill, Sukhi; Yiend, Jenny

    2015-01-01

    Information in the environment is frequently ambiguous in meaning. Emotional ambiguity, such as the stare of a stranger, or the scream of a child, encompasses possible good or bad emotional consequences. Those with elevated vulnerability to affective disorders tend to interpret such material more negatively than those without, a phenomenon known as "negative interpretation bias." In this study we examined the relationship between vulnerability to psychosis, measured by trait paranoia, and interpretation bias. One set of material permitted broadly positive/negative (valenced) interpretations, while another allowed more or less paranoid interpretations, allowing us to also investigate the content specificity of interpretation biases associated with paranoia. Regression analyses (n=70) revealed that trait paranoia, trait anxiety, and cognitive inflexibility predicted paranoid interpretation bias, whereas trait anxiety and cognitive inflexibility predicted negative interpretation bias. In a group comparison those with high levels of trait paranoia were negatively biased in their interpretations of ambiguous information relative to those with low trait paranoia, and this effect was most pronounced for material directly related to paranoid concerns. Together these data suggest that a negative interpretation bias occurs in those with elevated vulnerability to paranoia, and that this bias may be strongest for material matching paranoid beliefs. We conclude that content-specific biases may be important in the cause and maintenance of paranoid symptoms.

  19. A Model of DNA Repeat-Assembled Mitotic Chromosomal Skeleton

    OpenAIRE

    Shao-Jun Tang

    2011-01-01

    Despite intensive investigation for decades, the principle of higher-order organization of mitotic chromosomes is unclear. Here, I describe a novel model that emphasizes a critical role of interactions of homologous DNA repeats (repetitive elements; repetitive sequences) in mitotic chromosome architecture. According to the model, DNA repeats are assembled, via repeat interactions (pairing), into compact core structures that govern the arrangement of chromatins in mitotic chromosomes. Tandem r...

  20. New multi-purpose high copy number vector with greater mitotic stability for diverse applications in fission yeast Schizosaccharomyces pombe.

    Science.gov (United States)

    Verma, Hemant Kumar; Singh, Jagmohan

    2012-11-01

    We have constructed a pUC19-based multipurpose ATG vector in Schizosaccharomyces pombe with higher copy number and mitotic stability possible with commonly used vectors. The vector, having an NdeI site in its polylinker to provide ATG site for expression, carries a greatly truncated version of URA3 gene, URA3m, of Saccharomyces cerevisiae as a selection marker. In addition, it contains the mat2P-right flank region (mat2P-RF) of S. pombe as an autonomous replicating sequence (ARS) and a polylinker with wider choice of restriction sites. While URA3m confers an increase in plasmid copy number up to 200 copies/cell, mat2P-RF imparts greater mitotic stability than the standard ars1 element of S. pombe. Finally, the vector also includes the transcription termination signal of the nmt1 gene (Tnmt1). This basic vector should serve as a versatile tool for studies of gene function in S. pombe.

  1. Acrylamide effects on kinesin-related proteins of the mitotic/meiotic spindle

    International Nuclear Information System (INIS)

    The microtubule (MT) motor protein kinesin is a vital component of cells and organs expressing acrylamide (ACR) toxicity. As a mechanism of its potential carcinogenicity, we determined whether kinesins involved in cell division are inhibited by ACR similar to neuronal kinesin [Sickles, D.W., Brady, S.T., Testino, A.R., Friedman, M.A., and Wrenn, R.A. (1996). Direct effect of the neurotoxicant acrylamide on kinesin-based microtubule motility. Journal of Neuroscience Research 46, 7-17.] Kinesin-related genes were isolated from rat testes [Navolanic, P.M., and Sperry, A.O. (2000). Identification of isoforms of a mitotic motor in mammalian spermatogenesis. Biology of Reproduction 62, 1360-1369.], their kinesin-like proteins expressed in bacteria using recombinant DNA techniques and the effects of ACR, glycidamide (GLY) and propionamide (a non-neurotoxic metabolite) on the function of two of the identified kinesin motors were tested. KIFC5A MT bundling activity, required for mitotic spindle formation, was measured in an MT-binding assay. Both ACR and GLY caused a similar concentration-dependent reduction in the binding of MT; concentrations of 100 μM ACR or GLY reduced its activity by 60%. KRP2 MT disassembling activity was assayed using the quantity of tubulin disassembled from taxol-stabilized MT. Both ACR and GLY inhibited KRP2-induced MT disassembly. GLY was substantially more potent; significant reductions of 60% were achieved by 500 μM, a comparable inhibition by ACR required a 5 mM concentration. Propionamide had no significant effect on either kinesin, except KRP2 at 10 mM. This is the first report of ACR inhibition of a mitotic/meiotic motor protein. ACR (or GLY) inhibition of kinesin may be an alternative mechanism to DNA adduction in the production of cell division defects and potential carcinogenicity. We conclude that ACR may act on multiple kinesin family members and produce toxicities in organs highly dependent on microtubule-based functions

  2. Sequential phosphorylation of GRASP65 during mitotic Golgi disassembly

    Directory of Open Access Journals (Sweden)

    Danming Tang

    2012-09-01

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

  3. Microtubule Dynamics and Oscillating State for Mitotic Spindle

    CERN Document Server

    Rashid-Shomali, Safura

    2010-01-01

    We present a physical mechanism that can cause the mitotic spindle to oscillate. The driving force for this mechanism emerges from the polymerization of astral microtubules interacting with the cell cortex. We show that Brownian ratchet model for growing microtubules reaching the cell cortex, mediate an effective mass to the spindle body and therefore force it to oscillate. We compare the predictions of this mechanism with the previous mechanisms which were based on the effects of motor proteins. Finally we combine the effects of microtubules polymerization and motor proteins, and present the detailed phase diagram for possible oscillating states.

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

    Science.gov (United States)

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

    2016-08-01

    The Cyto-3D-print is an adapter that adds cytospin capability to a standard centrifuge. Like standard cytospinning, Cyto-3D-print increases the surface attachment of mitotic cells while giving a higher degree of adaptability to other slide chambers than available commercial devices. The use of Cyto-3D-print is cost effective, safe, and applicable to many slide designs. It is durable enough for repeated use and made of biodegradable materials for environment-friendly disposal. PMID:26464272

  5. Analysis of Codon Bias of NAD-ME Gene in Amaranthus hypochondriacus%籽粒苋苹果酸酶(NAD-ME)基因密码子偏好性分析

    Institute of Scientific and Technical Information of China (English)

    李平; 白云风; 冯瑞云; 王原媛; 张维锋

    2011-01-01

    遗传密码子是生命信息的基本遗传单位,每种氨基酸对应1~6个同义密码子.特定物种在长期进化中形成了适应自身基因组环境的密码子使用偏性.运用CHIPS、CUSP和CodonW程序分析自主克隆的籽粒苋NAD-ME基因的密码子偏好性,并与马铃薯等7种植物的ME基因密码子偏好性进行比较,以期为该基因在作物遗传改良中选择合适的受体植物提供依据.结果表明,籽粒苋NAD-ME基因偏好于以A或T结尾的密码子,其它几种被比较作物的ME基因也有同样的趋势,但双子叶植物的偏好性更强.基于NAD-ME基因的密码子使用偏性的系统聚类分析表明,籽粒苋与马铃薯、拟南芥、葡萄、蓖麻、毛果杨等双子叶植物聚为1类,玉米和高粱这2个单子叶植物聚为1类,预示籽粒苋NAD-ME基因更适合导入马铃薯等双子叶植物.对籽粒苋NAD-ME基因的密码子偏好性与大肠杆菌和酵母的基因组密码子偏好性进行比较,发现均存在差异,与大肠杆菌的差异高于酵母,表明酵母表达系统要优于大肠杆菌表达系统.若要进一步提高籽粒苋NAD-ME基因在大肠杆菌或酵母中的表达水平,尚需对其密码子进行优化.%Due to the degeneracy of genetic codon, most amino acids are coded by more than one codon (synonymous codons).Nucleotide coding sequences of many organisms exhibit significant codon bias, that is, unequal usage of synonymous codons.In this paper, coding sequence of NAD-dependent malic enzyme (NAD-ME) gene of Amaranthus hypochondriacus was analyzed by Codon W, CHIPS (Condon heterozygosity in a protein coding sequence) and CUSP (Create a codon usage table)programs for identifying codon bias and selecting appropriate expression systems.The results showed that NAD-ME gene of A.hypochondriacus was bias toward the synonymous codons with A and T at the third codon position.The phylogenic analysis suggested that NAD-ME gene of A.hypochondriacus was evolutionarily

  6. Political bias is tenacious.

    Science.gov (United States)

    Ditto, Peter H; Wojcik, Sean P; Chen, Eric Evan; Grady, Rebecca Hofstein; Ringel, Megan M

    2015-01-01

    Duarte et al. are right to worry about political bias in social psychology but they underestimate the ease of correcting it. Both liberals and conservatives show partisan bias that often worsens with cognitive sophistication. More non-liberals in social psychology is unlikely to speed our convergence upon the truth, although it may broaden the questions we ask and the data we collect.

  7. A comprehensive characterization of the nuclear microRNA repertoire of post-mitotic neurons

    Directory of Open Access Journals (Sweden)

    Sharof Abdumalikovich Khudayberdiev

    2013-11-01

    Full Text Available MicroRNAs (miRNAs are small non-coding RNAs with important functions in the development and plasticity of post-mitotic neurons. In addition to the well-described cytoplasmic function of miRNAs in post-transcriptional gene regulation, recent studies suggested that miRNAs could also be involved in transcriptional and post-transcriptional regulatory processes in the nuclei of proliferating cells. However, whether miRNAs localize to and function within the nucleus of post-mitotic neurons is unknown. Using a combination of microarray hybridization and small RNA deep sequencing, we identified a specific subset of miRNAs which are enriched in the nuclei of neurons. Nuclear enrichment of specific candidate miRNAs (miR-25 and miR-92a could be independently validated by Northern blot, quantitative real-time PCR (qRT-PCR and fluorescence in situ hybridization (FISH. By cross-comparison to published reports, we found that nuclear accumulation of miRNAs might be linked to a down-regulation of miRNA expression during in vitro development of cortical neurons. Importantly, by generating a comprehensive isomiR profile of the nuclear and cytoplasmic compartment, we found a significant overrepresentation of guanine nucleotides at the 3’ terminus of nuclear-enriched isomiRs, suggesting the presence of neuron-specific mechanisms involved in miRNA nuclear localization. In conclusion, our results provide a starting point for future studies addressing the nuclear function of specific miRNAs and the detailed mechanisms underlying subcellular localization of miRNAs in neurons and possibly other polarized cell types.

  8. Odorant receptor (OR) gene choice is biased and non-clonal in two olfactory placode cell lines, and OR RNA is nuclear prior to differentiation of these lines

    OpenAIRE

    Pathak, N; Johnson, P; Getman, M.; Lane, R. P.

    2008-01-01

    We have investigated two clonal mouse olfactory placode (OP) cell lines as a model system for studying endogenous odorant receptor (OR) regulation. Both lines can be differentiated into bipolar neurons with transcriptional profiles consistent with mature sensory neurons. We show that single cells exhibit monogenic OR expression like sensory neurons in vivo. Monogenic OR expression is established in undifferentiated cells and persists through differentiation, but OR gene choice is not a clonal...

  9. Meiotic recombination intermediates are resolved with minimal crossover formation during return-to-growth, an analogue of the mitotic cell cycle.

    Directory of Open Access Journals (Sweden)

    Yaron Dayani

    2011-05-01

    Full Text Available Accurate segregation of homologous chromosomes of different parental origin (homologs during the first division of meiosis (meiosis I requires inter-homolog crossovers (COs. These are produced at the end of meiosis I prophase, when recombination intermediates that contain Holliday junctions (joint molecules, JMs are resolved, predominantly as COs. JM resolution during the mitotic cell cycle is less well understood, mainly due to low levels of inter-homolog JMs. To compare JM resolution during meiosis and the mitotic cell cycle, we used a unique feature of Saccharomyces cerevisiae, return to growth (RTG, where cells undergoing meiosis can be returned to the mitotic cell cycle by a nutritional shift. By performing RTG with ndt80 mutants, which arrest in meiosis I prophase with high levels of interhomolog JMs, we could readily monitor JM resolution during the first cell division of RTG genetically and, for the first time, at the molecular level. In contrast to meiosis, where most JMs resolve as COs, most JMs were resolved during the first 1.5-2 hr after RTG without producing COs. Subsequent resolution of the remaining JMs produced COs, and this CO production required the Mus81/Mms4 structure-selective endonuclease. RTG in sgs1-ΔC795 mutants, which lack the helicase and Holliday junction-binding domains of this BLM homolog, led to a substantial delay in JM resolution; and subsequent JM resolution produced both COs and NCOs. Based on these findings, we suggest that most JMs are resolved during the mitotic cell cycle by dissolution, an Sgs1 helicase-dependent process that produces only NCOs. JMs that escape dissolution are mostly resolved by Mus81/Mms4-dependent cleavage that produces both COs and NCOs in a relatively unbiased manner. Thus, in contrast to meiosis, where JM resolution is heavily biased towards COs, JM resolution during RTG minimizes CO formation, thus maintaining genome integrity and minimizing loss of heterozygosity.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-10-01

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

  11. Integrin-linked kinase regulates interphase and mitotic microtubule dynamics.

    Directory of Open Access Journals (Sweden)

    Simin Lim

    Full Text Available Integrin-linked kinase (ILK localizes to both focal adhesions and centrosomes in distinct multiprotein complexes. Its dual function as a kinase and scaffolding protein has been well characterized at focal adhesions, where it regulates integrin-mediated cell adhesion, spreading, migration and signaling. At the centrosomes, ILK regulates mitotic spindle organization and centrosome clustering. Our previous study showed various spindle defects after ILK knockdown or inhibition that suggested alteration in microtubule dynamics. Since ILK expression is frequently elevated in many cancer types, we investigated the effects of ILK overexpression on microtubule dynamics. We show here that overexpressing ILK in HeLa cells was associated with a shorter duration of mitosis and decreased sensitivity to paclitaxel, a chemotherapeutic agent that suppresses microtubule dynamics. Measurement of interphase microtubule dynamics revealed that ILK overexpression favored microtubule depolymerization, suggesting that microtubule destabilization could be the mechanism behind the decreased sensitivity to paclitaxel, which is known to stabilize microtubules. Conversely, the use of a small molecule inhibitor selective against ILK, QLT-0267, resulted in suppressed microtubule dynamics, demonstrating a new mechanism of action for this compound. We further show that treatment of HeLa cells with QLT-0267 resulted in higher inter-centromere tension in aligned chromosomes during mitosis, slower microtubule regrowth after cold depolymerization and the presence of a more stable population of spindle microtubules. These results demonstrate that ILK regulates microtubule dynamics in both interphase and mitotic cells.

  12. Analysis of Codon Bias of MC1R Gene in Pig (Sus scrofa)%猪黑皮质素受体1基因密码子偏好分析

    Institute of Scientific and Technical Information of China (English)

    肖红卫; 刘西梅; 郑新民; 华文君; 李莉; 张立苹; 毕延震; 华再东

    2013-01-01

    遗传密码子是生命信息的基本遗传单位,每种氨基酸对应1~6个同义密码子。特定物种在长期进化中形成了适应自身基因环境的密码子使用偏好。运用CHIPS、CUPS和CodonW程序分析猪黑皮质素受体1基因密码子偏好,并与牛、羊、小鼠、人等多种动物的黑皮质素受体1基因密码子偏好进行比较,以期为转基因动物育种提供依据。结果表明,猪偏好使用以C、G结尾的密码子(96.88%),且在整个编码区序列中G+C含量(67.81%)大于A+T(32.19%),该基因在猪体内表达水平很高(CAI=0.849),并且发现,猪的密码子偏好性与牛、犬等动物类似,明显不同于鲀、雀、獾、大猩猩等动物。要实现目的基因在猪MC1R基因中进行定点整合并成功表达和尽可能地提高其表达量,需对目的基因的部分密码子进行改造。%Genetic codon is the basic hereditary unit of life information , and each amino acid is corresponding to 1~6 synony-mous codons.Specific organisms formed codon bias in long -term evolution to adapt their genetic environment .In this paper, the codon bias of MC1R gene in the pig was analyzed by Codon W , CHIPS and CUSP programs , and it was compared with that in vari-ous animals, such as cattle, sheep, mice, human etc., so as to provide a basis for transgenic animals breeding .The results showed that the pig preferred to use the codons ending with C and G (96.88%), the content of G+C (67.81%) was higher than that of A+T (32.19%) in the whole coding sequence , and MC1R gene in the pig had very high expression level (CAI=0.849).It was also found that the codon usage bias of the pig was similar to that of cattle , dog and so on , while it was obviously different from that of Takifugu rubripes, Taeniopygia guttata, Sarcophilus harrisii, Gorilla gorilla etc..In order to realize the site-specific integration of target gene into pig MC1R gene as well as its

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

    Science.gov (United States)

    Graem, N; Helweg-Larsen, K

    1979-09-01

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

  14. The progression of the intra-erythrocytic cell cycle of Plasmodium falciparum and the role of the centriolar plaques in asynchronous mitotic division during schizogony

    DEFF Research Database (Denmark)

    Arnot, David E; Ronander, Elena; Bengtsson, Dominique C

    2011-01-01

    model of cell cycle regulation. Using controlled synchronisation techniques, confocal microscopy to visualise key organelles and fluorescence in situ hybridization (FISH) to follow the movements and replication of genes and telomeres, we have re-analysed the timing and progression of mitotic events...

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

    Directory of Open Access Journals (Sweden)

    Yi Yin

    2013-10-01

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

  16. Detection Biases in Bluffing

    OpenAIRE

    Holm, Håkan J.

    2008-01-01

    Beliefs in signals that reveal lies or truths are widespread. These signals may lead to a truth or lie detection bias if the probability that such a signal is perceived by the receiver is contingent on the truth value of the sender’s message. Such detection biases are analyzed theoretically in a bluffing game. The detection bias shrinks the equilibrium set to a unique non-pooling equilibrium, in which the better a player is at detecting lies the more often the opponent player will lie. With p...

  17. INFLUENCE OF SODIUM METABISULPHITE (E 223) ON MITOTIC DIVISION IN CALENDULA OFFICINALIS L.s

    OpenAIRE

    Romeo-Cristian Marc; Gabriela Capraru

    2008-01-01

    This paper presents the cytogenetic effects induced by sodium metabisulphite (E 223) (a food additive used as preservative) in meristematic cells of Calendula officinalis L. root tips. The treatment has determined the lessening of the mitotic index (comparative with the control variant), until mitotic division total inhibition, as well as a growth frequency of division aberration in anaphase and telophase.

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

    Science.gov (United States)

    Po'uha, Sela T; Kavallaris, Maria

    2015-01-01

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

  19. Par1b induces asymmetric inheritance of plasma membrane domains via LGN-dependent mitotic spindle orientation in proliferating hepatocytes

    NARCIS (Netherlands)

    Slim, Christiaan L; Lázaro-Diéguez, Francisco; Bijlard, Marjolein; Toussaint, Mathilda J M; de Bruin, Alain; Du, Quansheng; Müsch, Anne; van Ijzendoorn, Sven C D

    2013-01-01

    The development and maintenance of polarized epithelial tissue requires a tightly controlled orientation of mitotic cell division relative to the apical polarity axis. Hepatocytes display a unique polarized architecture. We demonstrate that mitotic hepatocytes asymmetrically segregate their apical p

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

    Science.gov (United States)

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

    2014-01-01

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

  1. Simulating publication bias

    DEFF Research Database (Denmark)

    Paldam, Martin

    censoring: selection by the size of estimate; SR3 selects the optimal combination of fit and size; and SR4 selects the first satisficing result. The last four SRs are steered by priors and result in bias. The MST and the FAT-PET have been developed for detection and correction of such bias. The simulations...... are made by data variation, while the model is the same. It appears that SR0 generates narrow funnels much at odds with observed funnels, while the other four funnels look more realistic. SR1 to SR4 give the mean a substantial bias that confirms the prior causing the bias. The FAT-PET MRA works well...

  2. Introduction to Unconscious Bias

    Science.gov (United States)

    Schmelz, Joan T.

    2010-05-01

    We all have biases, and we are (for the most part) unaware of them. In general, men and women BOTH unconsciously devalue the contributions of women. This can have a detrimental effect on grant proposals, job applications, and performance reviews. Sociology is way ahead of astronomy in these studies. When evaluating identical application packages, male and female University psychology professors preferred 2:1 to hire "Brian” over "Karen” as an assistant professor. When evaluating a more experienced record (at the point of promotion to tenure), reservations were expressed four times more often when the name was female. This unconscious bias has a repeated negative effect on Karen's career. This talk will introduce the concept of unconscious bias and also give recommendations on how to address it using an example for a faculty search committee. The process of eliminating unconscious bias begins with awareness, then moves to policy and practice, and ends with accountability.

  3. Publication bias in situ

    Directory of Open Access Journals (Sweden)

    Phillips Carl V

    2004-08-01

    Full Text Available Abstract Background Publication bias, as typically defined, refers to the decreased likelihood of studies' results being published when they are near the null, not statistically significant, or otherwise "less interesting." But choices about how to analyze the data and which results to report create a publication bias within the published results, a bias I label "publication bias in situ" (PBIS. Discussion PBIS may create much greater bias in the literature than traditionally defined publication bias (the failure to publish any result from a study. The causes of PBIS are well known, consisting of various decisions about reporting that are influenced by the data. But its impact is not generally appreciated, and very little attention is devoted to it. What attention there is consists largely of rules for statistical analysis that are impractical and do not actually reduce the bias in reported estimates. PBIS cannot be reduced by statistical tools because it is not fundamentally a problem of statistics, but rather of non-statistical choices and plain language interpretations. PBIS should be recognized as a phenomenon worthy of study – it is extremely common and probably has a huge impact on results reported in the literature – and there should be greater systematic efforts to identify and reduce it. The paper presents examples, including results of a recent HIV vaccine trial, that show how easily PBIS can have a large impact on reported results, as well as how there can be no simple answer to it. Summary PBIS is a major problem, worthy of substantially more attention than it receives. There are ways to reduce the bias, but they are very seldom employed because they are largely unrecognized.

  4. Australia's Bond Home Bias

    OpenAIRE

    Mishra, Anil V; Umaru B. Conteh

    2014-01-01

    This paper constructs the float adjusted measure of home bias and explores the determinants of bond home bias by employing the International Monetary Fund's high quality dataset (2001 to 2009) on cross-border bond investment. The paper finds that Australian investors' prefer investing in countries with higher economic development and more developed bond markets. Exchange rate volatility appears to be an impediment for cross-border bond investment. Investors prefer investing in countries with ...

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

    Directory of Open Access Journals (Sweden)

    Moore Finola E

    2009-07-01

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

  6. Gender Bias in Tax Systems

    OpenAIRE

    Janet Gale Stotsky

    1996-01-01

    This paper examines the nature of gender bias in tax systems. Gender bias takes both explicit and implicit forms. Explicit gender bias is found in many personal income tax systems. Several countries, especially those in Western Europe, have undertaken to eliminate explicit gender bias in recent years. It is more difficult to identify implicit gender bias, since this depends in large part on value judgments as to desirable social and economic behavior. Implicit gender bias has also been a targ...

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

    Directory of Open Access Journals (Sweden)

    Napapat Amornwichet

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

  8. Mitotic recombination in callus of Arabidopsis thaliana (L.) Heynh. after fast-neutron treatment

    International Nuclear Information System (INIS)

    A threefold heterozygote plant, with marker genes as, py and er linked on chromosome 2, was used as material for this study. Six-week-old callus from leaves of this plant was irradiated with 15, 20 and 30 Gy of fast neutrons. A normal segregation was observed in the F2 progenies of about 65% of the callus-derived plants. On the other hand, a statistically significant deviation from the expected ratio of 3:1 was found in progenies of 17 other callus-derived plants. Only wild-type plants were observed in progenies of two plants from irradiated callus. Similar wild-type plants were present, at much higher frequencies than expected, in progenies of 15 other plants from irradiated callus. The mitotic recombination between the er gene and centromere in callus cells could be a reason for the appearance of only wild-type forms in progenies of callus-derived plants. These and other results presented in the paper suggest that fast-neutron irradiation may significantly increase the level of somatic crossing-over in callus cells. (author)

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

    Directory of Open Access Journals (Sweden)

    David eReboutier

    2015-12-01

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

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

    Science.gov (United States)

    Reboutier, David; Benaud, Christelle; Prigent, Claude

    2015-01-01

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

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

    Science.gov (United States)

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

    2014-02-21

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

  12. Cytoplasmic flows as signatures for the mechanics of mitotic positioning

    CERN Document Server

    Nazockdast, Ehssan; Needleman, Daniel; Shelley, Michael

    2015-01-01

    The proper positioning of the mitotic spindle is crucial for asymmetric cell division and generating cell diversity during development. Proper position in the single-cell embryo of Caenorhabditis elegans is achieved initially by the migration and rotation of the pronuclear complex (PNC) and its two associated centrosomal arrays of microtubules (MTs). We present here the first systematic theoretical study of how these $O(1000)$ centrosomal microtubules (MTs) interact through the immersing cytoplasm, the cell periphery and PNC, and with each other, to achieve proper position. This study is made possible through our development of a highly efficient and parallelized computational framework that accounts explicitly for long-ranged hydrodynamic interactions (HIs) between the MTs, while also capturing their flexibility, dynamic instability, and interactions with molecular motors and boundaries. First, we show through direct simulation that previous estimates of the PNC drag coefficient, based on either ignoring or ...

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    Lifescience Database Archive (English)

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

    Lifescience Database Archive (English)

    Full Text Available ALL.Emb.50.AllAg.Mitotic_cycle_13-14 dm3 All antigens Embryo Mitotic cycle 13-14 SR...X084384 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/ALL.Emb.50.AllAg.Mitotic_cycle_13-14.bed ...

  4. File list: Pol.Emb.50.AllAg.Mitotic_cycle_8-9 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Emb.50.AllAg.Mitotic_cycle_8-9 dm3 RNA polymerase Embryo Mitotic cycle 8-9 http...://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Pol.Emb.50.AllAg.Mitotic_cycle_8-9.bed ...

  5. File list: Pol.Emb.50.AllAg.Mitotic_cycle_11-13 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Emb.50.AllAg.Mitotic_cycle_11-13 dm3 RNA polymerase Embryo Mitotic cycle 11-13 ...http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Pol.Emb.50.AllAg.Mitotic_cycle_11-13.bed ...

  6. File list: InP.Emb.10.AllAg.Mitotic_cycle_12 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available InP.Emb.10.AllAg.Mitotic_cycle_12 dm3 Input control Embryo Mitotic cycle 12 SRX7500...69 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/InP.Emb.10.AllAg.Mitotic_cycle_12.bed ...

  7. File list: ALL.Emb.50.AllAg.Mitotic_cycle_8-9 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ALL.Emb.50.AllAg.Mitotic_cycle_8-9 dm3 All antigens Embryo Mitotic cycle 8-9 SRX084...383 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/ALL.Emb.50.AllAg.Mitotic_cycle_8-9.bed ...

  8. File list: NoD.Emb.05.AllAg.Mitotic_cycle_12-14 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available NoD.Emb.05.AllAg.Mitotic_cycle_12-14 dm3 No description Embryo Mitotic cycle 12-14 ...http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/NoD.Emb.05.AllAg.Mitotic_cycle_12-14.bed ...

  9. File list: InP.Emb.20.AllAg.Mitotic_cycle_11-13 [Chip-atlas[Archive

    Lifescience Database Archive (English)

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

  10. File list: Pol.Emb.10.AllAg.Mitotic_cycle_7-9 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Emb.10.AllAg.Mitotic_cycle_7-9 dm3 RNA polymerase Embryo Mitotic cycle 7-9 http...://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Pol.Emb.10.AllAg.Mitotic_cycle_7-9.bed ...

  11. File list: His.Emb.50.AllAg.Mitotic_cycle_11-13 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available His.Emb.50.AllAg.Mitotic_cycle_11-13 dm3 Histone Embryo Mitotic cycle 11-13 SRX6451...30,SRX645124,SRX645116,SRX645108,SRX645127,SRX645112,SRX645120 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/His.Emb.50.AllAg.Mitotic_cycle_11-13.bed ...

  12. File list: His.Emb.05.AllAg.Mitotic_cycle_11-13 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available His.Emb.05.AllAg.Mitotic_cycle_11-13 dm3 Histone Embryo Mitotic cycle 11-13 SRX6451...08,SRX645116,SRX645127,SRX645124,SRX645130,SRX645112,SRX645120 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/His.Emb.05.AllAg.Mitotic_cycle_11-13.bed ...

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

    Lifescience Database Archive (English)

    Full Text Available His.Emb.20.AllAg.Mitotic_cycle_13-14 dm3 Histone Embryo Mitotic cycle 13-14 http://...dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/His.Emb.20.AllAg.Mitotic_cycle_13-14.bed ...

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

    Lifescience Database Archive (English)

    Full Text Available Pol.Emb.50.AllAg.Mitotic_cycle_13-14 dm3 RNA polymerase Embryo Mitotic cycle 13-14 ...http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Pol.Emb.50.AllAg.Mitotic_cycle_13-14.bed ...

  15. File list: Pol.Emb.05.AllAg.Mitotic_cycle_11-13 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Emb.05.AllAg.Mitotic_cycle_11-13 dm3 RNA polymerase Embryo Mitotic cycle 11-13 ...http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Pol.Emb.05.AllAg.Mitotic_cycle_11-13.bed ...

  16. File list: DNS.Emb.20.AllAg.Mitotic_cycle_12-14 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available DNS.Emb.20.AllAg.Mitotic_cycle_12-14 dm3 DNase-seq Embryo Mitotic cycle 12-14 http:...//dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/DNS.Emb.20.AllAg.Mitotic_cycle_12-14.bed ...

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

    Lifescience Database Archive (English)

    Full Text Available InP.Emb.50.AllAg.Mitotic_cycle_14 dm3 Input control Embryo Mitotic cycle 14 SRX6451...40,SRX750075,SRX645139 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/InP.Emb.50.AllAg.Mitotic_cycle_14.bed ...

  18. File list: InP.Emb.50.AllAg.Mitotic_cycle_8-9 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available InP.Emb.50.AllAg.Mitotic_cycle_8-9 dm3 Input control Embryo Mitotic cycle 8-9 http:...//dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/InP.Emb.50.AllAg.Mitotic_cycle_8-9.bed ...

  19. File list: NoD.Emb.20.AllAg.Mitotic_cycle_7-9 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available NoD.Emb.20.AllAg.Mitotic_cycle_7-9 dm3 No description Embryo Mitotic cycle 7-9 http...://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/NoD.Emb.20.AllAg.Mitotic_cycle_7-9.bed ...

  20. File list: InP.Emb.50.AllAg.Mitotic_cycle_12-14 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available InP.Emb.50.AllAg.Mitotic_cycle_12-14 dm3 Input control Embryo Mitotic cycle 12-14 h...ttp://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/InP.Emb.50.AllAg.Mitotic_cycle_12-14.bed ...

  1. File list: DNS.Emb.50.AllAg.Mitotic_cycle_11-13 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available DNS.Emb.50.AllAg.Mitotic_cycle_11-13 dm3 DNase-seq Embryo Mitotic cycle 11-13 http:...//dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/DNS.Emb.50.AllAg.Mitotic_cycle_11-13.bed ...

  2. File list: InP.Emb.50.AllAg.Mitotic_cycle_7-9 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available InP.Emb.50.AllAg.Mitotic_cycle_7-9 dm3 Input control Embryo Mitotic cycle 7-9 SRX64...5137 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/InP.Emb.50.AllAg.Mitotic_cycle_7-9.bed ...

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

    Lifescience Database Archive (English)

    Full Text Available InP.Emb.05.AllAg.Mitotic_cycle_13 dm3 Input control Embryo Mitotic cycle 13 SRX7500...81,SRX750070 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/InP.Emb.05.AllAg.Mitotic_cycle_13.bed ...

  4. File list: InP.Emb.50.AllAg.Mitotic_cycle_13 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available InP.Emb.50.AllAg.Mitotic_cycle_13 dm3 Input control Embryo Mitotic cycle 13 SRX7500...81,SRX750070 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/InP.Emb.50.AllAg.Mitotic_cycle_13.bed ...

  5. File list: Unc.Emb.05.AllAg.Mitotic_cycle_11-13 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Unc.Emb.05.AllAg.Mitotic_cycle_11-13 dm3 Unclassified Embryo Mitotic cycle 11-13 ht...tp://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Unc.Emb.05.AllAg.Mitotic_cycle_11-13.bed ...

  6. File list: DNS.Emb.05.AllAg.Mitotic_cycle_12-14 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available DNS.Emb.05.AllAg.Mitotic_cycle_12-14 dm3 DNase-seq Embryo Mitotic cycle 12-14 http:...//dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/DNS.Emb.05.AllAg.Mitotic_cycle_12-14.bed ...

  7. File list: InP.Emb.10.AllAg.Mitotic_cycle_8-9 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available InP.Emb.10.AllAg.Mitotic_cycle_8-9 dm3 Input control Embryo Mitotic cycle 8-9 http:...//dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/InP.Emb.10.AllAg.Mitotic_cycle_8-9.bed ...

  8. File list: Unc.Emb.05.AllAg.Mitotic_cycle_13-14 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Unc.Emb.05.AllAg.Mitotic_cycle_13-14 dm3 Unclassified Embryo Mitotic cycle 13-14 ht...tp://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Unc.Emb.05.AllAg.Mitotic_cycle_13-14.bed ...

  9. File list: Pol.Emb.10.AllAg.Mitotic_cycle_11-13 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Emb.10.AllAg.Mitotic_cycle_11-13 dm3 RNA polymerase Embryo Mitotic cycle 11-13 ...http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Pol.Emb.10.AllAg.Mitotic_cycle_11-13.bed ...

  10. File list: InP.Emb.20.AllAg.Mitotic_cycle_14 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available InP.Emb.20.AllAg.Mitotic_cycle_14 dm3 Input control Embryo Mitotic cycle 14 SRX6451...40,SRX750075,SRX645139 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/InP.Emb.20.AllAg.Mitotic_cycle_14.bed ...

  11. File list: Pol.Emb.50.AllAg.Mitotic_cycle_7-9 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Emb.50.AllAg.Mitotic_cycle_7-9 dm3 RNA polymerase Embryo Mitotic cycle 7-9 http...://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Pol.Emb.50.AllAg.Mitotic_cycle_7-9.bed ...

  12. File list: Unc.Emb.50.AllAg.Mitotic_cycle_12-14 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Unc.Emb.50.AllAg.Mitotic_cycle_12-14 dm3 Unclassified Embryo Mitotic cycle 12-14 ht...tp://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Unc.Emb.50.AllAg.Mitotic_cycle_12-14.bed ...

  13. File list: ALL.Emb.20.AllAg.Mitotic_cycle_12-14 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ALL.Emb.20.AllAg.Mitotic_cycle_12-14 dm3 All antigens Embryo Mitotic cycle 12-14 SR...X647436,SRX647437,SRX647440,SRX647442,SRX647441,SRX647443 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/ALL.Emb.20.AllAg.Mitotic_cycle_12-14.bed ...

  14. File list: Pol.Emb.20.AllAg.Mitotic_cycle_11-13 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Emb.20.AllAg.Mitotic_cycle_11-13 dm3 RNA polymerase Embryo Mitotic cycle 11-13 ...http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Pol.Emb.20.AllAg.Mitotic_cycle_11-13.bed ...

  15. File list: Pol.Emb.05.AllAg.Mitotic_cycle_13-14 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Emb.05.AllAg.Mitotic_cycle_13-14 dm3 RNA polymerase Embryo Mitotic cycle 13-14 ...http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Pol.Emb.05.AllAg.Mitotic_cycle_13-14.bed ...

  16. File list: Pol.Emb.05.AllAg.Mitotic_cycle_8-9 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Emb.05.AllAg.Mitotic_cycle_8-9 dm3 RNA polymerase Embryo Mitotic cycle 8-9 http...://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Pol.Emb.05.AllAg.Mitotic_cycle_8-9.bed ...

  17. File list: His.Emb.05.AllAg.Mitotic_cycle_13-14 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available His.Emb.05.AllAg.Mitotic_cycle_13-14 dm3 Histone Embryo Mitotic cycle 13-14 http://...dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/His.Emb.05.AllAg.Mitotic_cycle_13-14.bed ...

  18. File list: InP.Emb.05.AllAg.Mitotic_cycle_13-14 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available InP.Emb.05.AllAg.Mitotic_cycle_13-14 dm3 Input control Embryo Mitotic cycle 13-14 h...ttp://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/InP.Emb.05.AllAg.Mitotic_cycle_13-14.bed ...

  19. File list: NoD.Emb.10.AllAg.Mitotic_cycle_7-9 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available NoD.Emb.10.AllAg.Mitotic_cycle_7-9 dm3 No description Embryo Mitotic cycle 7-9 http...://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/NoD.Emb.10.AllAg.Mitotic_cycle_7-9.bed ...

  20. File list: Oth.Emb.20.AllAg.Mitotic_cycle_7-9 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.Emb.20.AllAg.Mitotic_cycle_7-9 dm3 TFs and others Embryo Mitotic cycle 7-9 http...://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Oth.Emb.20.AllAg.Mitotic_cycle_7-9.bed ...

  1. File list: Pol.Emb.20.AllAg.Mitotic_cycle_8-9 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Emb.20.AllAg.Mitotic_cycle_8-9 dm3 RNA polymerase Embryo Mitotic cycle 8-9 http...://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Pol.Emb.20.AllAg.Mitotic_cycle_8-9.bed ...

  2. File list: NoD.Emb.05.AllAg.Mitotic_cycle_11-13 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available NoD.Emb.05.AllAg.Mitotic_cycle_11-13 dm3 No description Embryo Mitotic cycle 11-13 ...http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/NoD.Emb.05.AllAg.Mitotic_cycle_11-13.bed ...

  3. File list: Unc.Emb.50.AllAg.Mitotic_cycle_11-13 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Unc.Emb.50.AllAg.Mitotic_cycle_11-13 dm3 Unclassified Embryo Mitotic cycle 11-13 ht...tp://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Unc.Emb.50.AllAg.Mitotic_cycle_11-13.bed ...

  4. File list: ALL.Emb.05.AllAg.Mitotic_cycle_13-14 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ALL.Emb.05.AllAg.Mitotic_cycle_13-14 dm3 All antigens Embryo Mitotic cycle 13-14 SR...X084384 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/ALL.Emb.05.AllAg.Mitotic_cycle_13-14.bed ...

  5. File list: Oth.Emb.05.AllAg.Mitotic_cycle_8-9 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.Emb.05.AllAg.Mitotic_cycle_8-9 dm3 TFs and others Embryo Mitotic cycle 8-9 SRX0...84383 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Oth.Emb.05.AllAg.Mitotic_cycle_8-9.bed ...

  6. File list: InP.Emb.05.AllAg.Mitotic_cycle_12 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available InP.Emb.05.AllAg.Mitotic_cycle_12 dm3 Input control Embryo Mitotic cycle 12 SRX7500...69 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/InP.Emb.05.AllAg.Mitotic_cycle_12.bed ...

  7. File list: InP.Emb.10.AllAg.Mitotic_cycle_12-14 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available InP.Emb.10.AllAg.Mitotic_cycle_12-14 dm3 Input control Embryo Mitotic cycle 12-14 h...ttp://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/InP.Emb.10.AllAg.Mitotic_cycle_12-14.bed ...

  8. File list: InP.Emb.20.AllAg.Mitotic_cycle_12-14 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available InP.Emb.20.AllAg.Mitotic_cycle_12-14 dm3 Input control Embryo Mitotic cycle 12-14 h...ttp://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/InP.Emb.20.AllAg.Mitotic_cycle_12-14.bed ...

  9. File list: DNS.Emb.05.AllAg.Mitotic_cycle_11-13 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available DNS.Emb.05.AllAg.Mitotic_cycle_11-13 dm3 DNase-seq Embryo Mitotic cycle 11-13 http:...//dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/DNS.Emb.05.AllAg.Mitotic_cycle_11-13.bed ...

  10. File list: Oth.Emb.20.AllAg.Mitotic_cycle_11-13 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.Emb.20.AllAg.Mitotic_cycle_11-13 dm3 TFs and others Embryo Mitotic cycle 11-13 ...http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Oth.Emb.20.AllAg.Mitotic_cycle_11-13.bed ...

  11. File list: ALL.Emb.50.AllAg.Mitotic_cycle_12-14 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ALL.Emb.50.AllAg.Mitotic_cycle_12-14 dm3 All antigens Embryo Mitotic cycle 12-14 SR...X647436,SRX647440,SRX647442,SRX647441,SRX647443,SRX647437 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/ALL.Emb.50.AllAg.Mitotic_cycle_12-14.bed ...

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

    Lifescience Database Archive (English)

    Full Text Available InP.Emb.50.AllAg.Mitotic_cycle_12 dm3 Input control Embryo Mitotic cycle 12 SRX7500...69 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/InP.Emb.50.AllAg.Mitotic_cycle_12.bed ...

  13. In-silico modeling of the mitotic spindle assembly checkpoint.

    Directory of Open Access Journals (Sweden)

    Bashar Ibrahim

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

  14. Expression of regulators of mitotic fidelity are associated with intercellular heterogeneity and chromosomal instability in primary breast cancer

    DEFF Research Database (Denmark)

    Roylance, Rebecca; Endesfelder, David; Jamal-Hanjani, Mariam;

    2014-01-01

    , as determined by centromeric FISH and defined by modal centromere deviation, was analysed. Significantly poorer clinical outcome was observed in patients with high AURKA expression levels. Expression of SURVIVIN was elevated in ER-negative relative to ER-positive breast cancer. Both AURKA and SURVIVIN increased...... expression were significantly associated with breast cancer grade. There was a significant association between increased CIN and both increased AURKA and SURVIVIN expression. AURKA gene amplification was also associated with increased CIN. To our knowledge this is the largest study assessing CIN status...... in parallel with the expression of the mitotic regulators AURKA and SURVIVIN. These data suggest that elevated expression of AURKA and SURVIVIN, together with AURKA gene amplification, are associated with increased CIN in breast cancer, and may be used as a proxy for CIN in breast cancer samples...

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

    Directory of Open Access Journals (Sweden)

    Ivan Ivanovski

    2015-11-01

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

  16. Association of Mitotic Regulation Pathway Polymorphisms with Pancreatic Cancer Risk and Outcome

    Science.gov (United States)

    Couch, Fergus J.; Wang, Xianshu; Bamlet, William R.; de Andrade, Mariza; Petersen, Gloria M.; McWilliams, Robert R.

    2009-01-01

    Background Mitosis is a highly regulated process that serves to ensure the fidelity of cell division. Disruption of mitotic regulators leading to aneuploidy and polyploidy is commonly observed in cancer cells. Single nucleotide polymorphisms (SNPs) in regulators of mitosis may promote chromosome mis-segregation and influence pancreatic cancer and/or survival. Methods Thirty four SNPs, previously associated with breast cancer risk, from 33 genes involved in regulation of mitosis, were investigated for associations with pancreatic cancer risk in 1,143 Caucasian patients with pancreatic adenocarcinoma and 1,097 unaffected controls from the Mayo Clinic. Associations with survival from pancreatic cancer were also assessed using 1,030 pancreatic cancer cases with known outcome. Results Two SNPs in the APC (rs2431238) and NIN (rs10145182) loci, out of 34 examined, were significantly associated with pancreatic cancer risk (p=0.035 and p=0.038, respectively). Further analyses of individuals categorized by smoking and BMI identified several SNPs displaying significant associations (p<0.05) with pancreatic cancer risk, including APC rs2431238 in individuals with high body mass index (BMI≥30) (p=0.031) and NIN rs10145182 in ever smokers (p=0.01). In addition, survival analyses detected significant associations between SNPs in EIF3S10 and overall survival (p=0.009), SNPs from five genes and survival in resected cancer cases (p<0.05), and SNPs from two other genes (p<0.05) and survival of locally advanced cancer cases. Conclusion Common variation in genes encoding regulators of mitosis may independently influence pancreatic cancer susceptibility and survival. PMID:20056645

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

    Science.gov (United States)

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

    2011-05-01

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

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

    Science.gov (United States)

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

    2015-05-01

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

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

    Science.gov (United States)

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

    2012-06-19

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

  20. Measuring Agricultural Bias

    DEFF Research Database (Denmark)

    Jensen, Henning Tarp; Robinson, Sherman; Tarp, Finn

    The measurement issue is the key issue in the literature on trade policy-induced agri-cultural price incentive bias. This paper introduces a general equilibrium effective rate of protection (GE-ERP) measure, which extends and generalizes earlier partial equilibrium nominal protection measures....... For the 15 sample countries, the results indicate that the agricultural price incentive bias, which was generally perceived to exist during the 1980s, was largely eliminated during the 1990s. The results also demonstrate that general equilibrium effects and country-specific characteristics - including trade...... shares and intersectoral linkages - are crucial for determining the sign and magnitude of trade policy bias. The GE-ERP measure is therefore uniquely suited to capture the full impact of trade policies on agricultural price incentives. A Monte Carlo procedure confirms that the results are robust...

  1. Meiotic and Mitotic Cell Cycle Mutants Involved in Gametophyte Development in Arabidopsis

    Institute of Scientific and Technical Information of China (English)

    Jingjing Liu; Li-Jia Qu

    2008-01-01

    The alternation between diploid and haploid generations is fundamentalin the life cycles of both animals and plants.The meiotic cell cycle is common to both animals and plants gamete formation, but in animals the products of meiosis are gametes,whereas for most plants,subsequent mitotic cell cycles are needed for their formation. Clarifying the regulatory mechanisms of mitotic cell cycle progression during gametophyte development will help understanding of sexual reproduction in plants.Many mutants defective in gametophyte development and,in particular,many meiotic and mitotic cell cycle mutants in Arabidopsis male and female gametophyte development were identified through both forward and reverse genetics approaches.

  2. Candidate SNP Markers of Gender-Biased Autoimmune Complications of Monogenic Diseases Are Predicted by a Significant Change in the Affinity of TATA-Binding Protein for Human Gene Promoters

    Science.gov (United States)

    Ponomarenko, Mikhail P.; Arkova, Olga; Rasskazov, Dmitry; Ponomarenko, Petr; Savinkova, Ludmila; Kolchanov, Nikolay

    2016-01-01

    Some variations of human genome [for example, single nucleotide polymorphisms (SNPs)] are markers of hereditary diseases and drug responses. Analysis of them can help to improve treatment. Computer-based analysis of millions of SNPs in the 1000 Genomes project makes a search for SNP markers more targeted. Here, we combined two computer-based approaches: DNA sequence analysis and keyword search in databases. In the binding sites for TATA-binding protein (TBP) in human gene promoters, we found candidate SNP markers of gender-biased autoimmune diseases, including rs1143627 [cachexia in rheumatoid arthritis (double prevalence among women)]; rs11557611 [demyelinating diseases (thrice more prevalent among young white women than among non-white individuals)]; rs17231520 and rs569033466 [both: atherosclerosis comorbid with related diseases (double prevalence among women)]; rs563763767 [Hughes syndrome-related thrombosis (lethal during pregnancy)]; rs2814778 [autoimmune diseases (excluding multiple sclerosis and rheumatoid arthritis) underlying hypergammaglobulinemia in women]; rs72661131 and rs562962093 (both: preterm delivery in pregnant diabetic women); and rs35518301, rs34166473, rs34500389, rs33981098, rs33980857, rs397509430, rs34598529, rs33931746, rs281864525, and rs63750953 (all: autoimmune diseases underlying hypergammaglobulinemia in women). Validation of these predicted candidate SNP markers using the clinical standards may advance personalized medicine. PMID:27092142

  3. Measuring agricultural policy bias

    DEFF Research Database (Denmark)

    Jensen, Henning Tarp; Robinson, Sherman; Tarp, Finn

    2010-01-01

    Measurement is a key issue in the literature on price incentive bias induced by trade policy. We introduce a general equilibrium measure of the relative effective rate of protection, which generalizes earlier protection measures. For our fifteen sample countries, results indicate...... protection measure is therefore uniquely suited to capture the full impact of trade policies on relative agricultural price incentives....

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

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Nam Hyun [Department of Pharmacology, Kwandong University College of Medicine, Gangneung 210-701 (Korea, Republic of); Kim, Su-Nam [KIST Gangneung Institute, Gangneung 210-340 (Korea, Republic of); Oh, Joa Sub [College of Pharmacy, Dankook University, Cheonan 330-714 (Korea, Republic of); Lee, Seokjoon [Department of Basic Science, Kwandong University College of Medicine, Gangneung 210-701 (Korea, Republic of); Kim, Yong Kee, E-mail: yksnbk@sookmyung.ac.kr [College of Pharmacy, Sookmyung Women' s University, Seoul 140-742 (Korea, Republic of)

    2012-02-24

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

  5. Genotoxic profile of inhibitors of topoisomerases I (camptothecin) and II (etoposide) in a mitotic recombination and sex-chromosome loss somatic eye assay of Drosophila melanogaster.

    Science.gov (United States)

    Sortibrán, América Nitxin Castañeda; Téllez, María Guadalupe Ordaz; Rodríguez-Arnaiz, Rosario

    2006-04-30

    Genotoxic carcinogens which interact with DNA may produce double-strand breaks as normal intermediates of homologous mitotic recombination, and may give rise to structural chromosome aberrations and inter-chromosomal deletion-recombination. The genotoxic profile of two inhibitors of DNA topoisomerases were evaluated using an in vivo somatic w/w+ eye assay of Drosophila melanogaster for the detection of loss of heterozygosity (LOH) by homologous mitotic recombination, intra-chromosomal recombination and structural chromosomal aberrations. We studied camptothecin (CPT) as a topoisomerase-I-interactive agent and etoposide (ETOP) as a topoisomerase II inhibitor. These drugs act by stabilizing a ternary complex consisting of topoisomerases covalently linked to DNA at single-strand or at double-strand breaks, thereby preventing the relegation step of the breakage/rejoining reaction mediated by the enzyme. The genotoxic profiles were determined from the appearance of eye tissue in adult flies, in which LOH and expression of the reporter gene white produced light clones. The results demonstrated that both compounds were significantly genotoxic, with CPT being more effective than ETOP. Inter-chromosomal mitotic recombination was the major mechanism responsible for the induction of light spots by both compounds in XX females. Loss of the ring X chromosome (rX), was significantly enhanced by CPT, and this topoisomerase blocker also produced intra-chromosomal recombination (XY males). PMID:16529987

  6. Mitotic delay following inhibition by 5'-fluorodeoxyuridine of S-phase in Physarum is not due to delay in termination of S-phase.

    Science.gov (United States)

    Kauffman, S A; Shymko, R M

    1982-02-01

    It has been known for several years that inhibition by 5'-fluorodeoxyuridine (FdUrd) of DNA synthesis in plasmodia of Physarum polycephalum delays subsequent nuclear mitosis. To test whether this delay is due to delay in the termination of S-phase, we blocked DNA synthesis with FdUrd + uridine for 3 h at different stages of S-phase, and in plasmodia with different cycle times. The results show that in short-cycling plasmodia the delay in mitosis can be as long as 9 h, despite little delay in termination of S-phase, and is longest when plasmodia are blocked in early S-phase. In plasmodia with long cycle times, no mitotic delay following 3 h inhibition by FdUrd of S-phase is observed. Our results suggest that mitotic delay after pulses of FdUrd is not due to delay in termination of S-phase, which therefore does not appear to 'gate' entry into a G2 period of fixed length. The fact that delay is longest after FdUrd blocks in early S-phase suggests that normal progress through S-phase, not its termination, is critical for the timing of the subsequent mitosis. This may reflect an obligate coupling between replication and transcription of specific genes needed for progress toward mitosis. The lack of mitotic delay in long-cycling plasmodia shows that S-phase-coupled processes need not act as 'timers' if other processes become rate-limiting.

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

    Science.gov (United States)

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

    2013-05-13

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

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

    Science.gov (United States)

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

    2016-08-01

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

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

    Science.gov (United States)

    Harley, C B

    1991-01-01

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

  10. Maintaining Genome Stability in Defiance of Mitotic DNA Damage

    Science.gov (United States)

    Ferrari, Stefano; Gentili, Christian

    2016-01-01

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

  11. Centromeric barrier disruption leads to mitotic defects in Schizosaccharomyces pombe.

    Science.gov (United States)

    Gaither, Terilyn L; Merrett, Stephanie L; Pun, Matthew J; Scott, Kristin C

    2014-04-01

    Centromeres are cis-acting chromosomal domains that direct kinetochore formation, enabling faithful chromosome segregation and preserving genome stability. The centromeres of most eukaryotic organisms are structurally complex, composed of nonoverlapping, structurally and functionally distinct chromatin subdomains, including the specialized core chromatin that underlies the kinetochore and pericentromeric heterochromatin. The genomic and epigenetic features that specify and preserve the adjacent chromatin subdomains critical to centromere identity are currently unknown. Here we demonstrate that chromatin barriers regulate this process in Schizosaccharomyces pombe. Reduced fitness and mitotic chromosome segregation defects occur in strains that carry exogenous DNA inserted at centromere 1 chromatin barriers. Abnormal phenotypes are accompanied by changes in the structural integrity of both the centromeric core chromatin domain, containing the conserved CENP-A(Cnp1) protein, and the flanking pericentric heterochromatin domain. Barrier mutant cells can revert to wild-type growth and centromere structure at a high frequency after the spontaneous excision of integrated exogenous DNA. Our results reveal a previously undemonstrated role for chromatin barriers in chromosome segregation and in the prevention of genome instability. PMID:24531725

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

    Science.gov (United States)

    Ferrari, Stefano; Gentili, Christian

    2016-01-01

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

  13. A chemical tool box defines mitotic and interphase roles for Mps1 kinase

    OpenAIRE

    Lan, Weijie; Don W Cleveland

    2010-01-01

    In this issue, three groups (Hewitt et al. 2010. J. Cell Biol. doi:10.1083/jcb.201002133; Maciejowski et al. 2010. J. Cell Biol. doi:10.1083/jcb.201001050; Santaguida et al. 2010. J. Cell Biol. doi:10.1083/jcb.201001036) use chemical inhibitors to analyze the function of the mitotic checkpoint kinase Mps1. These studies demonstrate that Mps1 kinase activity ensures accurate chromosome segregation through its recruitment to kinetochores of mitotic checkpoint proteins, formation of interphase a...

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

    OpenAIRE

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

    2006-01-01

    The E2 protein segregates episomal bovine papillomavirus (BPV) genomes to daughter cells by tethering them to mitotic chromosomes, thus ensuring equal distribution and retention of viral DNA. To date, only the BPV1 E2 protein has been shown to bind to mitotic chromosomes. We assessed the localization of 13 different animal and human E2 proteins from seven papillomavirus genera, and we show that most of them are stably bound to chromosomes throughout mitosis. Furthermore, in contrast to the ra...

  15. Dovitinib induces mitotic defects and activates the G2 DNA damage checkpoint

    OpenAIRE

    Man, Wing Yu; Mak, Joyce PY; Poon, Randy YC

    2013-01-01

    Dovitinib (TKI258; formerly CHIR-258) is an orally bioavailable inhibitor of multiple receptor tyrosine kinases. Interestingly, Dovitinib triggered a G2/M arrest in cancer cell lines from diverse origins including HeLa, nasopharyngeal carcinoma, and hepatocellular carcinoma. Single-cell analysis revealed that Dovitinib promoted a delay in mitotic exit in a subset of cells, causing the cells to undergo mitotic slippage. Higher concentrations of Dovitinib induced a G2 arrest similar to the G2 D...

  16. Effects of the rad52 gene on recombination in Saccharomyces cerevisiae

    International Nuclear Information System (INIS)

    Effects of the rad52 mutation in Saccharomyces cerevisiae on meiotic, γ-ray-induced, uv-induced, and spontaneous mitotic recombination were studied. The rad52/rad52 diploids undergo premeiotic DNA synthesis; sporulation occurs but inviable spores are produced. Intra- and intergenic recombination during meiosis were examined in cells transferred from sporulation medium to vegetative medium at different time intervals. No intragenic recombination was observed at the hisl-1/hisl-315 and trp5-2/trp5-48 heteroalleles. Gene-centromere recombination was also not observed in rad52/rad52 diploids. No γ-ray-induced intragenic mitotic recombination is seen in rad52/rad52 diploids and uv-induced intragenic recombination is greatly reduced. However, spontaneous mitotic recombination is not similarly affected. The RAD52 gene thus functions in recombination in meiosis and in γ-ray and uv-induced mitotic recombination but not in spontaneous mitotic recombination

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

    Science.gov (United States)

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

    2016-09-01

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

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

    Science.gov (United States)

    Hyun, Sun-Yi; Jang, Young-Joo

    2015-03-10

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

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

    Science.gov (United States)

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

    2012-08-01

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

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

    Science.gov (United States)

    Ritchey, Lisa; Chakrabarti, Ratna

    2014-11-01

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

  1. Temperature trend biases

    Science.gov (United States)

    Venema, Victor; Lindau, Ralf

    2016-04-01

    In an accompanying talk we show that well-homogenized national dataset warm more than temperatures from global collections averaged over the region of common coverage. In this poster we want to present auxiliary work about possible biases in the raw observations and on how well relative statistical homogenization can remove trend biases. There are several possible causes of cooling biases, which have not been studied much. Siting could be an important factor. Urban stations tend to move away from the centre to better locations. Many stations started inside of urban areas and are nowadays more outside. Even for villages the temperature difference between the centre and edge can be 0.5°C. When a city station moves to an airport, which often happened around WWII, this takes the station (largely) out of the urban heat island. During the 20th century the Stevenson screen was established as the dominant thermometer screen. This screen protected the thermometer much better against radiation than earlier designs. Deficits of earlier measurement methods have artificially warmed the temperatures in the 19th century. Newer studies suggest we may have underestimated the size of this bias. Currently we are in a transition to Automatic Weather Stations. The net global effect of this transition is not clear at this moment. Irrigation on average decreases the 2m-temperature by about 1 degree centigrade. At the same time, irrigation has increased significantly during the last century. People preferentially live in irrigated areas and weather stations serve agriculture. Thus it is possible that there is a higher likelihood that weather stations are erected in irrigated areas than elsewhere. In this case irrigation could lead to a spurious cooling trend. In the Parallel Observations Science Team of the International Surface Temperature Initiative (ISTI-POST) we are studying influence of the introduction of Stevenson screens and Automatic Weather Stations using parallel measurements

  2. Mitotic evolution of Plasmodium falciparum shows a stable core genome but recombination in antigen families.

    Directory of Open Access Journals (Sweden)

    Selina E R Bopp

    Full Text Available Malaria parasites elude eradication attempts both within the human host and across nations. At the individual level, parasites evade the host immune responses through antigenic variation. At the global level, parasites escape drug pressure through single nucleotide variants and gene copy amplification events conferring drug resistance. Despite their importance to global health, the rates at which these genomic alterations emerge have not been determined. We studied the complete genomes of different Plasmodium falciparum clones that had been propagated asexually over one year in the presence and absence of drug pressure. A combination of whole-genome microarray analysis and next-generation deep resequencing (totaling 14 terabases revealed a stable core genome with only 38 novel single nucleotide variants appearing in seventeen evolved clones (avg. 5.4 per clone. In clones exposed to atovaquone, we found cytochrome b mutations as well as an amplification event encompassing the P. falciparum multidrug resistance associated protein (mrp1 on chromosome 1. We observed 18 large-scale (>1 kb on average deletions of telomere-proximal regions encoding multigene families, involved in immune evasion (9.5×10(-6 structural variants per base pair per generation. Six of these deletions were associated with chromosomal crossovers generated during mitosis. We found only minor differences in rates between genetically distinct strains and between parasites cultured in the presence or absence of drug. Using these derived mutation rates for P. falciparum (1.0-9.7×10(-9 mutations per base pair per generation, we can now model the frequency at which drug or immune resistance alleles will emerge under a well-defined set of assumptions. Further, the detection of mitotic recombination events in var gene families illustrates how multigene families can arise and change over time in P. falciparum. These results will help improve our understanding of how P. falciparum

  3. Assessing Bias in Search Engines.

    Science.gov (United States)

    Mowshowitz, Abbe; Kawaguchi, Akira

    2002-01-01

    Addresses the measurement of bias in search engines on the Web, defining bias as the balance and representation of items in a collection retrieved from a database for a set of queries. Assesses bias by measuring the deviation from the ideal of the distribution produced by a particular search engine. (Author/LRW)

  4. Test Bias and the Elimination of Racism

    Science.gov (United States)

    Sedlacek, William E.

    1977-01-01

    Three types of test bias are discussed: content bias, atmosphere bias, and use bias. Use bias is considered the most important. Tests reflect the bias in society, and eliminating test bias means eliminating racism and sexism in society. A six-stage model to eliminate racism and sexism is presented. (Author)

  5. The transcription factor ERG recruits CCR4-NOT to control mRNA decay and mitotic progression.

    Science.gov (United States)

    Rambout, Xavier; Detiffe, Cécile; Bruyr, Jonathan; Mariavelle, Emeline; Cherkaoui, Majid; Brohée, Sylvain; Demoitié, Pauline; Lebrun, Marielle; Soin, Romuald; Lesage, Bart; Guedri, Katia; Beullens, Monique; Bollen, Mathieu; Farazi, Thalia A; Kettmann, Richard; Struman, Ingrid; Hill, David E; Vidal, Marc; Kruys, Véronique; Simonis, Nicolas; Twizere, Jean-Claude; Dequiedt, Franck

    2016-07-01

    Control of mRNA levels, a fundamental aspect in the regulation of gene expression, is achieved through a balance between mRNA synthesis and decay. E26-related gene (Erg) proteins are canonical transcription factors whose previously described functions are confined to the control of mRNA synthesis. Here, we report that ERG also regulates gene expression by affecting mRNA stability and identify the molecular mechanisms underlying this function in human cells. ERG is recruited to mRNAs via interaction with the RNA-binding protein RBPMS, and it promotes mRNA decay by binding CNOT2, a component of the CCR4-NOT deadenylation complex. Transcriptome-wide mRNA stability analysis revealed that ERG controls the degradation of a subset of mRNAs highly connected to Aurora signaling, whose decay during S phase is necessary for mitotic progression. Our data indicate that control of gene expression by mammalian transcription factors may follow a more complex scheme than previously anticipated, integrating mRNA synthesis and degradation. PMID:27273514

  6. The fission yeast protein p73res2 is an essential component of the mitotic MBF complex and a master regulator of meiosis.

    OpenAIRE

    Ayté, J; Leis, J F; DeCaprio, J A

    1997-01-01

    Depending on environmental conditions, Schizosaccharomyces pombe can remain in the stationary phase or enter into either premitotic or premeiotic DNA synthesis. This decision point is known as Start. In the mitotic cell cycle, regulation of G1/S-specific gene expression is dependent upon the MBF (Mlu1 binding factor) complex, known to contain p85cdc10 and p72res1. Here we demonstrate that p73res2 controls cell cycle progression via its participation in the MBF complex, interacting directly wi...

  7. Bias of genetic trend of genomic predictions based on both real dairy cattle and simulated data

    DEFF Research Database (Denmark)

    Ma, Peipei; Lund, Mogens Sandø; Nielsen, Ulrik Sander;

    population. In simulated data, there was no bias when the test animals were unselected cows. When the G matrix was derived from genotypes of causal genes, the bias was reduced. The results suggest that the main reasons for causing the bias of the prediction trends are the selection of bulls and bull dams......This study investigated the phenomenon of bias in the trend of genomic predictions and attempted to find the reason and solution for this bias. The data used in this study include Danish Jersey data and simulation data. In Jersey data, the bias was reduced when cows were included in the reference...

  8. File list: ALL.Emb.50.AllAg.Mitotic_cycle_7-9 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ALL.Emb.50.AllAg.Mitotic_cycle_7-9 dm3 All antigens Embryo Mitotic cycle 7-9 SRX645...111,SRX645115,SRX645103,SRX645123,SRX645107,SRX645137,SRX645099,SRX645119 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/ALL.Emb.50.AllAg.Mitotic_cycle_7-9.bed ...

  9. File list: ALL.Emb.05.AllAg.Mitotic_cycle_7-9 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ALL.Emb.05.AllAg.Mitotic_cycle_7-9 dm3 All antigens Embryo Mitotic cycle 7-9 SRX645...103,SRX645115,SRX645099,SRX645107,SRX645111,SRX645119,SRX645123,SRX645137 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/ALL.Emb.05.AllAg.Mitotic_cycle_7-9.bed ...

  10. File list: ALL.Emb.10.AllAg.Mitotic_cycle_7-9 [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ALL.Emb.10.AllAg.Mitotic_cycle_7-9 dm3 All antigens Embryo Mitotic cycle 7-9 SRX645...103,SRX645115,SRX645111,SRX645119,SRX645123,SRX645107,SRX645137,SRX645099 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/ALL.Emb.10.AllAg.Mitotic_cycle_7-9.bed ...

  11. Mitosis Phase Enrichment with Identification of Mitotic Centromere-Associated Kinesin As a Therapeutic Target in Castration-Resistant Prostate Cancer

    Science.gov (United States)

    Sircar, Kanishka; Huang, Heng; Hu, Limei; Liu, Yuexin; Dhillon, Jasreman; Cogdell, David; Aprikian, Armen; Efstathiou, Eleni; Navone, Nora; Troncoso, Patricia; Zhang, Wei

    2012-01-01

    The recently described transcriptomic switch to a mitosis program in castration-resistant prostate cancer (CRPC) suggests that mitotic proteins may be rationally targeted at this lethal stage of the disease. In this study, we showed upregulation of the mitosis-phase at the protein level in our cohort of 51 clinical CRPC cases and found centrosomal aberrations to also occur preferentially in CRPC compared with untreated, high Gleason–grade hormone-sensitive prostate cancer (P<0.0001). Expression profiling of chemotherapy-resistant CRPC samples (n = 25) was performed, and the results were compared with data from primary chemotherapy-naïve CRPC (n = 10) and hormone-sensitive prostate cancer cases (n = 108). Our results showed enrichment of mitosis-phase genes and pathways, with progression to both castration-resistant and chemotherapy-resistant disease. The mitotic centromere-associated kinesin (MCAK) was identified as a novel mitosis-phase target in prostate cancer that was overexpressed in multiple CRPC gene-expression datasets. We found concordant gene expression of MCAK between our parent and murine CRPC xenograft pairs and increased MCAK protein expression with clinical progression of prostate cancer to a castration-resistant disease stage. Knockdown of MCAK arrested the growth of prostate cancer cells suggesting its utility as a potential therapeutic target. PMID:22363599

  12. Mitosis phase enrichment with identification of mitotic centromere-associated kinesin as a therapeutic target in castration-resistant prostate cancer.

    Directory of Open Access Journals (Sweden)

    Kanishka Sircar

    Full Text Available The recently described transcriptomic switch to a mitosis program in castration-resistant prostate cancer (CRPC suggests that mitotic proteins may be rationally targeted at this lethal stage of the disease. In this study, we showed upregulation of the mitosis-phase at the protein level in our cohort of 51 clinical CRPC cases and found centrosomal aberrations to also occur preferentially in CRPC compared with untreated, high Gleason-grade hormone-sensitive prostate cancer (P<0.0001. Expression profiling of chemotherapy-resistant CRPC samples (n = 25 was performed, and the results were compared with data from primary chemotherapy-naïve CRPC (n = 10 and hormone-sensitive prostate cancer cases (n = 108. Our results showed enrichment of mitosis-phase genes and pathways, with progression to both castration-resistant and chemotherapy-resistant disease. The mitotic centromere-associated kinesin (MCAK was identified as a novel mitosis-phase target in prostate cancer that was overexpressed in multiple CRPC gene-expression datasets. We found concordant gene expression of MCAK between our parent and murine CRPC xenograft pairs and increased MCAK protein expression with clinical progression of prostate cancer to a castration-resistant disease stage. Knockdown of MCAK arrested the growth of prostate cancer cells suggesting its utility as a potential therapeutic target.

  13. The Exon Junction Complex Controls the Efficient and Faithful Splicing of a Subset of Transcripts Involved in Mitotic Cell-Cycle Progression.

    Science.gov (United States)

    Fukumura, Kazuhiro; Wakabayashi, Shunichi; Kataoka, Naoyuki; Sakamoto, Hiroshi; Suzuki, Yutaka; Nakai, Kenta; Mayeda, Akila; Inoue, Kunio

    2016-01-01

    The exon junction complex (EJC) that is deposited onto spliced mRNAs upstream of exon-exon junctions plays important roles in multiple post-splicing gene expression events, such as mRNA export, surveillance, localization, and translation. However, a direct role for the human EJC in pre-mRNA splicing has not been fully understood. Using HeLa cells, we depleted one of the EJC core components, Y14, and the resulting transcriptome was analyzed by deep sequencing (RNA-Seq) and confirmed by RT-PCR. We found that Y14 is required for efficient and faithful splicing of a group of transcripts that is enriched in short intron-containing genes involved in mitotic cell-cycle progression. Tethering of EJC core components (Y14, eIF4AIII or MAGOH) to a model reporter pre-mRNA harboring a short intron showed that these core components are prerequisites for the splicing activation. Taken together, we conclude that the EJC core assembled on pre-mRNA is critical for efficient and faithful splicing of a specific subset of short introns in mitotic cell cycle-related genes. PMID:27490541

  14. Impaired mitotic progression and preimplantation lethality in mice lacking OMCG1, a new evolutionarily conserved nuclear protein

    DEFF Research Database (Denmark)

    Artus, Jérôme; Vandormael-Pournin, Sandrine; Frödin, Morten;

    2005-01-01

    . In vitro cultured Omcg1-null blastocysts exhibit a dramatic reduction in the total cell number, a high mitotic index, and the presence of abnormal mitotic figures. Importantly, we found that Omcg1 disruption results in the lengthening of M phase rather than in a mitotic block. We show that the mitotic...... delay in Omcg1-/- embryos is associated with neither a dysfunction of the spindle checkpoint nor abnormal global histone modifications. Taken together, these results suggest that Omcg1 is an important regulator of the cell cycle in the preimplantation embryo....

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-08-12

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

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

    Science.gov (United States)

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

    2015-01-01

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

  17. Effect of caffeine and adenosine on G2 repair: mitotic delay and chromosome damage.

    Science.gov (United States)

    González-Fernández, A; Hernández, P; López-Sáez, J F

    1985-04-01

    Proliferating plant cells treated during the late S period with 5-aminouracil (AU), give the typical response that DNA-damaging agents induce, characterized by: an important mitotic delay, and a potentiation of the chromosome damage by caffeine post-treatment. The study of labelled prophases, after a tritiated thymidine pulse, allowed evaluation of the mitotic delay induced by AU as well as its reversion by caffeine, while chromosome damage was estimated by the percentage of anaphases and telophases showing chromosomal aberrations. Post-treatment with adenosine alone has shown no effect on mitotic delay or chromosomal damage. However, when cells after AU were incubated in caffeine plus adenosine, the chromosome damage potentiation was abolished without affecting the caffeine action on mitotic delay. As a consequence, we postulate that caffeine could have two effects on G2 cells with damaged DNA: the first, to cancel their mitotic delay and the second to inhibit some DNA-repair pathway(s). Only this last effect could be reversed by adenosine.

  18. The KASH protein Kms2 coordinates mitotic remodeling of the spindle pole body.

    Science.gov (United States)

    Wälde, Sarah; King, Megan C

    2014-08-15

    Defects in the biogenesis of the spindle pole body (SPB), the yeast centrosome equivalent, can lead to monopolar spindles and mitotic catastrophe. The KASH domain protein Kms2 and the SUN domain protein Sad1 colocalize within the nuclear envelope at the site of SPB attachment during interphase and at the spindle poles during mitosis in Schizosaccharomyces pombe. We show that Kms2 interacts with the essential SPB components Cut12 and Pcp1 and the Polo kinase Plo1. Depletion of Kms2 delays mitotic entry and leads to defects in the insertion of the SPB into the nuclear envelope, disrupting stable bipolar spindle formation. These effects are mediated in part by a delay in the recruitment of Plo1 to the SPB at mitotic entry. Plo1 activity supports mitotic SPB remodeling by driving a burst of incorporation of Cut12 and Pcp1. Thus, a fission yeast SUN-KASH complex plays an important role in supporting the remodeling of the SPB at mitotic entry.

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

    Science.gov (United States)

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

    2015-09-25

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

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

    Science.gov (United States)

    Stevens, Deanna; Oegema, Karen; Desai, Arshad

    2013-12-01

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

  1. UV-C irradiation delays mitotic progression by recruiting Mps1 to kinetochores.

    Science.gov (United States)

    Zhang, Xiaojuan; Ling, Youguo; Wang, Wenjun; Zhang, Yanhong; Ma, Qingjun; Tan, Pingping; Song, Ting; Wei, Congwen; Li, Ping; Liu, Xuedong; Ma, Runlin Z; Zhong, Hui; Cao, Cheng; Xu, Quanbin

    2013-04-15

    The effect of UV irradiation on replicating cells during interphase has been studied extensively. However, how the mitotic cell responds to UV irradiation is less well defined. Herein, we found that UV-C irradiation (254 nm) increases recruitment of the spindle checkpoint proteins Mps1 and Mad2 to the kinetochore during metaphase, suggesting that the spindle assembly checkpoint (SAC) is reactivated. In accordance with this, cells exposed to UV-C showed delayed mitotic progression, characterized by a prolonged chromosomal alignment during metaphase. UV-C irradiation also induced the DNA damage response and caused a significant accumulation of γ-H2AX on mitotic chromosomes. Unexpectedly, the mitotic delay upon UV-C irradiation is not due to the DNA damage response but to the relocation of Mps1 to the kinetochore. Further, we found that UV-C irradiation activates Aurora B kinase. Importantly, the kinase activity of Aurora B is indispensable for full recruitment of Mps1 to the kinetochore during both prometaphase and metaphase. Taking these findings together, we propose that UV irradiation delays mitotic progression by evoking the Aurora B-Mps1 signaling cascade, which exerts its role through promoting the association of Mps1 with the kinetochore in metaphase.

  2. Molecular mechanism of APC/C activation by mitotic phosphorylation.

    Science.gov (United States)

    Zhang, Suyang; Chang, Leifu; Alfieri, Claudio; Zhang, Ziguo; Yang, Jing; Maslen, Sarah; Skehel, Mark; Barford, David

    2016-04-27

    results reveal the mechanism for the regulation of mitotic APC/C by phosphorylation and provide a rationale for the development of selective inhibitors of this state.

  3. Inhibition of Survivin and Aurora B Kinase Sensitizes Mesothelioma Cells by Enhancing Mitotic Arrests

    International Nuclear Information System (INIS)

    Purpose: Survivin, a member of the inhibitor of apoptosis gene family, has also been shown to regulate mitosis. It binds Aurora B kinase and the inner centromere protein to form the chromosome passenger complex. Both Aurora B and survivin are overexpressed in many tumors. In this study, we examined whether irradiation affected survivin and Aurora B expression in mesothelioma cells, and how inhibition of these molecules affected radiosensitivity. Methods and Materials: ZM447439 and survivin antisense oligonucleotides were used to inhibit survivin and Aurora B kinase respectively. Western blot was performed to determine the expression of survivin, Aurora B, phosphorylated-histone H3 (Ser 10), and caspase cleavage. Multinucleated cells were counted using flow cytometry, and cell survival after treatment was determined using clonogenic assay. Results: At 3-Gy irradiation an increase was observed in levels of survivin and Aurora B as well as the kinase activity of Aurora B, with an increase in G2/M phase. The radiation-induced upregulation of these molecules was effectively attenuated by antisense oligonucleotides against survivin and a small-molecule inhibitor of Aurora B, ZM447439. Dual inhibition of survivin and Aurora B synergistically radiosensitized mesothelioma cells with a dose enhancement ratio of 2.55. This treatment resulted in increased formation of multinucleated cells after irradiation but did not increase levels of cleaved caspase 3. Conclusion: Inhibition of survivin and Aurora B induces mitotic cell arrest in mesothelioma cells after irradiation. These two proteins may be potential therapeutic targets for the enhancement of radiotherapy in malignant pleural mesothelioma

  4. HDAC1 inactivation induces mitotic defect and caspase-independent autophagic cell death in liver cancer.

    Directory of Open Access Journals (Sweden)

    Hong Jian Xie

    Full Text Available Histone deacetylases (HDACs are known to play a central role in the regulation of several cellular properties interlinked with the development and progression of cancer. Recently, HDAC1 has been reported to be overexpressed in hepatocellular carcinoma (HCC, but its biological roles in hepatocarcinogenesis remain to be elucidated. In this study, we demonstrated overexpression of HDAC1 in a subset of human HCCs and liver cancer cell lines. HDAC1 inactivation resulted in regression of tumor cell growth and activation of caspase-independent autophagic cell death, via LC3B-II activation pathway in Hep3B cells. In cell cycle regulation, HDAC1 inactivation selectively induced both p21(WAF1/Cip1 and p27(Kip1 expressions, and simultaneously suppressed the expression of cyclin D1 and CDK2. Consequently, HDAC1 inactivation led to the hypophosphorylation of pRb in G1/S transition, and thereby inactivated E2F/DP1 transcription activity. In addition, we demonstrated that HDAC1 suppresses p21(WAF1/Cip1 transcriptional activity through Sp1-binding sites in the p21(WAF1/Cip1 promoter. Furthermore, sustained suppression of HDAC1 attenuated in vitro colony formation and in vivo tumor growth in a mouse xenograft model. Taken together, we suggest the aberrant regulation of HDAC1 in HCC and its epigenetic regulation of gene transcription of autophagy and cell cycle components. Overexpression of HDAC1 may play a pivotal role through the systemic regulation of mitotic effectors in the development of HCC, providing a particularly relevant potential target in cancer therapy.

  5. AtPPR2, an Arabidopsis pentatricopeptide repeat protein, binds to plastid 23S rRNA and plays an important role in the first mitotic division during gametogenesis and in cell proliferation during embryogenesis

    OpenAIRE

    Lu, Yuqing; Li, Cong; Wang, Hai; Chen, Hao; Berg, Howard; Xia, Yiji

    2011-01-01

    Pentatricopeptide repeat (PPR) proteins are mainly involved in regulating post-transcriptional processes in mitochondria and plastids, including chloroplasts. Mutations in the Arabidopsis PPR2 gene have previously been found to cause defects in seed development and reduced transmission through male and female gametophytes. However, the exact function of AtPPR2 has not been defined. We found that a loss-of-function mutation of AtPPR2 leads to arrest of the first mitotic division during both ma...

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

    Science.gov (United States)

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

    1999-07-01

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

  7. Generation of large homozygous chromosomal segments by mitotic recombination during lymphomagenesis in F{sub 1} hybrid mice

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Doo-Pyo; Mori, Nobuko; Umesako, Seiichi; Okumoto, Masaaki [Osaka Prefectural Univ., Sakai (Japan). Research Inst. for Advanced Science and Technology; Kubo, Kihei; Tsugawa, Naomi [Osaka Prefectural Univ., Sakai (Japan). Graduate School of Agriculture and Biological Sciences; Song, Chang-Woo [Korea Research Inst. of Chemical Technology, Taejon (Korea, Republic of)

    2002-06-01

    The loss of heterozygosity (LOH) has been reported in numerous neoplasms in both human and animals, and has often been observed in chromosomal regions, which contain tumor-suppressor genes. We previously found frequent LOH on chromosomes 4, 12 and 19 in radiation-induced lymphomas from (BALB/cHeA x STS/A)F{sub 1} hybrid mice by allelotype analysis at polymorphic microsatellite loci. In this study, to elucidate the nature of allelic losses, we refined the loss regions on chromosomes 4, 12 and 19 of the tumors from the F{sub 1} mice and then analyzed them cytogenetically. The results represent evidence of a wide range of allelic losses owing to mitotic recombination on chromosomes 4 and 19 in the tumors, possibly reflecting functional losses of putative tumor-suppressor genes. It is suggested that the generation of these large homozygous chromosomal segments probably containing the affected genes is one of the genetic alterations responsible for tumorigenesis. (author)

  8. A Model of DNA Repeat-Assembled Mitotic Chromosomal Skeleton

    Directory of Open Access Journals (Sweden)

    Shao-Jun Tang

    2011-09-01

    Full Text Available Despite intensive investigation for decades, the principle of higher-order organization of mitotic chromosomes is unclear. Here, I describe a novel model that emphasizes a critical role of interactions of homologous DNA repeats (repetitive elements; repetitive sequences in mitotic chromosome architecture. According to the model, DNA repeats are assembled, via repeat interactions (pairing, into compact core structures that govern the arrangement of chromatins in mitotic chromosomes. Tandem repeat assemblies form a chromosomal axis to coordinate chromatins in the longitudinal dimension, while dispersed repeat assemblies form chromosomal nodes around the axis to organize chromatins in the halo. The chromosomal axis and nodes constitute a firm skeleton on which non-skeletal chromatins can be anchored, folded, and supercoiled.

  9. A model of DNA repeat-assembled mitotic chromosomal skeleton.

    Science.gov (United States)

    Tang, Shao-Jun

    2011-01-01

    Despite intensive investigation for decades, the principle of higher-order organization of mitotic chromosomes is unclear. Here, I describe a novel model that emphasizes a critical role of interactions of homologous DNA repeats (repetitive elements; repetitive sequences) in mitotic chromosome architecture. According to the model, DNA repeats are assembled, via repeat interactions (pairing), into compact core structures that govern the arrangement of chromatins in mitotic chromosomes. Tandem repeat assemblies form a chromosomal axis to coordinate chromatins in the longitudinal dimension, while dispersed repeat assemblies form chromosomal nodes around the axis to organize chromatins in the halo. The chromosomal axis and nodes constitute a firm skeleton on which non-skeletal chromatins can be anchored, folded, and supercoiled.

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

    DEFF Research Database (Denmark)

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

    2015-01-01

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

  11. Mitotic cells contract actomyosin cortex and generate pressure to round against or escape epithelial confinement

    Science.gov (United States)

    Sorce, Barbara; Escobedo, Carlos; Toyoda, Yusuke; Stewart, Martin P.; Cattin, Cedric J.; Newton, Richard; Banerjee, Indranil; Stettler, Alexander; Roska, Botond; Eaton, Suzanne; Hyman, Anthony A.; Hierlemann, Andreas; Müller, Daniel J.

    2015-11-01

    Little is known about how mitotic cells round against epithelial confinement. Here, we engineer micropillar arrays that subject cells to lateral mechanical confinement similar to that experienced in epithelia. If generating sufficient force to deform the pillars, rounding epithelial (MDCK) cells can create space to divide. However, if mitotic cells cannot create sufficient space, their rounding force, which is generated by actomyosin contraction and hydrostatic pressure, pushes the cell out of confinement. After conducting mitosis in an unperturbed manner, both daughter cells return to the confinement of the pillars. Cells that cannot round against nor escape confinement cannot orient their mitotic spindles and more likely undergo apoptosis. The results highlight how spatially constrained epithelial cells prepare for mitosis: either they are strong enough to round up or they must escape. The ability to escape from confinement and reintegrate after mitosis appears to be a basic property of epithelial cells.

  12. p12 tethers the murine leukemia virus pre-integration complex to mitotic chromosomes.

    Directory of Open Access Journals (Sweden)

    Efrat Elis

    2012-12-01

    Full Text Available The p12 protein of the murine leukemia virus (MLV is a constituent of the pre-integration complex (PIC but its function in this complex remains unknown. We developed an imaging system to monitor MLV PIC trafficking in live cells. This allowed the visualization of PIC docking to mitotic chromosomes and its release upon exit from mitosis. Docking occurred concomitantly with nuclear envelope breakdown and was impaired for PICs of viruses with lethal p12 mutations. Insertion of a heterologous chromatin binding module into p12 of one of these mutants restored PICs attachment to the chromosomes and partially rescued virus replication. Capsid dissociated from wild type PICs in mitotic cells but remained associated with PICs harboring tethering-negative p12 mutants. Altogether, these results explain, in part, MLV restriction to dividing cells and reveal a role for p12 as a factor that tethers MLV PIC to mitotic chromosomes.

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

    Science.gov (United States)

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

    2012-03-01

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

  14. Bistability of mitotic entry and exit switches during open mitosis in mammalian cells.

    Science.gov (United States)

    Hégarat, Nadia; Rata, Scott; Hochegger, Helfrid

    2016-07-01

    Mitotic entry and exit are switch-like transitions that are driven by the activation and inactivation of Cdk1 and mitotic cyclins. This simple on/off reaction turns out to be a complex interplay of various reversible reactions, feedback loops, and thresholds that involve both the direct regulators of Cdk1 and its counteracting phosphatases. In this review, we summarize the interplay of the major components of the system and discuss how they work together to generate robustness, bistability, and irreversibility. We propose that it may be beneficial to regard the entry and exit reactions as two separate reversible switches that are distinguished by differences in the state of phosphatase activity, mitotic proteolysis, and a dramatic rearrangement of cellular components after nuclear envelope breakdown, and discuss how the major Cdk1 activity thresholds could be determined for these transitions. PMID:27231150

  15. Gene

    Data.gov (United States)

    U.S. Department of Health & Human Services — Gene integrates information from a wide range of species. A record may include nomenclature, Reference Sequences (RefSeqs), maps, pathways, variations, phenotypes,...

  16. Codon Bias Patterns of E. coli’s Interacting Proteins

    OpenAIRE

    Dilucca, Maddalena; Cimini, Giulio; Semmoloni, Andrea; Deiana, Antonio; Giansanti, Andrea

    2015-01-01

    Synonymous codons, i.e., DNA nucleotide triplets coding for the same amino acid, are used differently across the variety of living organisms. The biological meaning of this phenomenon, known as codon usage bias, is still controversial. In order to shed light on this point, we propose a new codon bias index, CompAI, that is based on the competition between cognate and near-cognate tRNAs during translation, without being tuned to the usage bias of highly expressed genes. We perform a genome-wid...

  17. Measuring nonlocal Lagrangian peak bias

    CERN Document Server

    Biagetti, Matteo; Desjacques, Vincent; Paranjape, Aseem

    2013-01-01

    In the Lagrangian approach to halo clustering, nonlocal bias can be generated either in the initial conditions or by the subsequent gravitational motions. Here, we investigate nonlocal Lagrangian bias contributions involving gradients of the linear density field, for which we have predictions from the excursion set peak formalism. We reformulate this approach in order to explicitly take into account the variable describing the crossing of the collapse barrier. This enables us to write down a bias expansion which includes all the bias terms, including the nonlocal ones. Having checked that the model furnishes a reasonable fit to the halo mass function, we extend the 1-point cross-correlation technique of Musso, Paranjape & Sheth (2012) to bias contributions that are chi-squared distributed. We validate the method with numerical realizations of peaks of Gaussian random fields before applying it to N-body simulations. We focus on the lowest (quadratic) order nonlocal bias factors predicted by the excursion s...

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

    Science.gov (United States)

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

    2013-03-01

    Several authors have demonstrated an increased number of mitotic figures in breast cancer resection specimen when compared with biopsy material. This has been ascribed to a sampling artifact where biopsies are (i) either too small to allow formal mitotic figure counting or (ii) not necessarily taken form the proliferating tumor periphery. Herein, we propose a different explanation for this phenomenon. Biopsy and resection material of 52 invasive ductal carcinomas was studied. We counted mitotic figures in 10 representative high power fields and quantified MIB-1 immunohistochemistry by visual estimation, counting and image analysis. We found that mitotic figures were elevated by more than three-fold on average in resection specimen over biopsy material from the same tumors (20±6 vs 6±2 mitoses per 10 high power fields, P=0.008), and that this resulted in a relative diminution of post-metaphase figures (anaphase/telophase), which made up 7% of all mitotic figures in biopsies but only 3% in resection specimen (Pmitotic figures in resection specimen. We propose that the increase in mitotic figures in resection specimen and the significant shift towards metaphase figures is not due to a sampling artifact, but reflects ongoing cell cycle activity in the resected tumor tissue due to fixation delay. The dwindling energy supply will eventually arrest tumor cells in metaphase, where they are readily identified by the diagnostic pathologist. Taken together, we suggest that the rapidly fixed biopsy material better represents true tumor biology and should be privileged as predictive marker of putative response to cytotoxic chemotherapy.

  19. Two success-biased social learning strategies.

    Science.gov (United States)

    Baldini, Ryan

    2013-06-01

    I compare the evolutionary dynamics of two success-biased social learning strategies, which, by definition, use the success of others to inform one's social learning decisions. The first, "Compare Means", causes a learner to adopt cultural variants with highest mean payoff in her sample. The second, "Imitate the Best", causes a learner to imitate the single most successful individual in her sample. I summarize conditions under which each strategy performs well or poorly, and investigate their evolution via a gene-culture coevolutionary model. Despite the adaptive appeal of these strategies, both encounter conditions under which they systematically perform worse than simply imitating at random. Compare Means performs worst when the optimal cultural variant is usually at high frequency, while Imitate the Best performs worst when suboptimal variants sometimes produce high payoffs. The extent to which it is optimal to use success-biased social learning depends strongly on the payoff distributions and environmental conditions that human social learners face.

  20. Theoretical investigation of exchange bias

    Institute of Scientific and Technical Information of China (English)

    Xiong Zhi-Jie; Wang Huai-Yu; Ding Ze-Jun

    2007-01-01

    The exchange bias of bilayer magnetic films consisting of ferromagnetic (FM) and antiferromagnetic (AFM) layers in an uncompensated case is studied by use of the many-body Green's function method of quantum statistical theory.The effects of the layer thickness and temperature and the interfacial coupling strength on the exchange bias HE are investigated. The dependence of the exchange bias HE on the FM layer thickness and temperature is qualitatively in agreement with experimental results. When temperature varies, both the coercivity HC and HE decrease with the temperature increasing. For each FM thickness, there exists a least AFM thickness in which the exchange bias occurs,which is called pinning thickness.

  1. Eukaryotic evolutionary transitions are associated with extreme codon bias in functionally-related proteins.

    Directory of Open Access Journals (Sweden)

    Nicholas J Hudson

    Full Text Available Codon bias in the genome of an organism influences its phenome by changing the speed and efficiency of mRNA translation and hence protein abundance. We hypothesized that differences in codon bias, either between-species differences in orthologous genes, or within-species differences between genes, may play an evolutionary role. To explore this hypothesis, we compared the genome-wide codon bias in six species that occupy vital positions in the Eukaryotic Tree of Life. We acquired the entire protein coding sequences for these organisms, computed the codon bias for all genes in each organism and explored the output for relationships between codon bias and protein function, both within- and between-lineages. We discovered five notable coordinated patterns, with extreme codon bias most pronounced in traits considered highly characteristic of a given lineage. Firstly, the Homo sapiens genome had stronger codon bias for DNA-binding transcription factors than the Saccharomyces cerevisiae genome, whereas the opposite was true for ribosomal proteins--perhaps underscoring transcriptional regulation in the origin of complexity. Secondly, both mammalian species examined possessed extreme codon bias in genes relating to hair--a tissue unique to mammals. Thirdly, Arabidopsis thaliana showed extreme codon bias in genes implicated in cell wall formation and chloroplast function--which are unique to plants. Fourthly, Gallus gallus possessed strong codon bias in a subset of genes encoding mitochondrial proteins--perhaps reflecting the enhanced bioenergetic efficiency in birds that co-evolved with flight. And lastly, the G. gallus genome had extreme codon bias for the Ciliary Neurotrophic Factor--which may help to explain their spontaneous recovery from deafness. We propose that extreme codon bias in groups of genes that encode functionally related proteins has a pathway-level energetic explanation.

  2. Information environment, behavioral biases, and home bias in analysts’ recommendations

    DEFF Research Database (Denmark)

    Farooq, Omar; Taouss, Mohammed

    2012-01-01

    Can information environment of a firm explain home bias in analysts’ recommendations? Can the extent of agency problems explain optimism difference between foreign and local analysts? This paper answers these questions by documenting the effect of information environment on home bias in analysts’...

  3. 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.

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

    Directory of Open Access Journals (Sweden)

    Gang Zhang

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

  5. Natural product Celastrol destabilizes tubulin heterodimer and facilitates mitotic cell death triggered by microtubule-targeting anti-cancer drugs.

    Directory of Open Access Journals (Sweden)

    Hakryul Jo

    Full Text Available BACKGROUND: Microtubule drugs are effective anti-cancer agents, primarily due to their ability to induce mitotic arrest and subsequent cell death. However, some cancer cells are intrinsically resistant or acquire a resistance. Lack of apoptosis following mitotic arrest is thought to contribute to drug resistance that limits the efficacy of the microtubule-targeting anti-cancer drugs. Genetic or pharmacological agents that selectively facilitate the apoptosis of mitotic arrested cells present opportunities to strengthen the therapeutic efficacy. METHODOLOGY AND PRINCIPAL FINDINGS: We report a natural product Celastrol targets tubulin and facilitates mitotic cell death caused by microtubule drugs. First, in a small molecule screening effort, we identify Celastrol as an inhibitor of neutrophil chemotaxis. Subsequent time-lapse imaging analyses reveal that inhibition of microtubule-mediated cellular processes, including cell migration and mitotic chromosome alignment, is the earliest events affected by Celastrol. Disorganization, not depolymerization, of mitotic spindles appears responsible for mitotic defects. Celastrol directly affects the biochemical properties of tubulin heterodimer in vitro and reduces its protein level in vivo. At the cellular level, Celastrol induces a synergistic apoptosis when combined with conventional microtubule-targeting drugs and manifests an efficacy toward Taxol-resistant cancer cells. Finally, by time-lapse imaging and tracking of microtubule drug-treated cells, we show that Celastrol preferentially induces apoptosis of mitotic arrested cells in a caspase-dependent manner. This selective effect is not due to inhibition of general cell survival pathways or mitotic kinases that have been shown to enhance microtubule drug-induced cell death. CONCLUSIONS AND SIGNIFICANCE: We provide evidence for new cellular pathways that, when perturbed, selectively induce the apoptosis of mitotic arrested cancer cells, identifying a

  6. Bias in clinical intervention research

    DEFF Research Database (Denmark)

    Gluud, Lise Lotte

    2006-01-01

    Research on bias in clinical trials may help identify some of the reasons why investigators sometimes reach the wrong conclusions about intervention effects. Several quality components for the assessment of bias control have been suggested, but although they seem intrinsically valid, empirical...

  7. Mammalian neurogenesis requires Treacle-Plk1 for precise control of spindle orientation, mitotic progression, and maintenance of neural progenitor cells.

    Directory of Open Access Journals (Sweden)

    Daisuke Sakai

    Full Text Available The cerebral cortex is a specialized region of the brain that processes cognitive, motor, somatosensory, auditory, and visual functions. Its characteristic architecture and size is dependent upon the number of neurons generated during embryogenesis and has been postulated to be governed by symmetric versus asymmetric cell divisions, which mediate the balance between progenitor cell maintenance and neuron differentiation, respectively. The mechanistic importance of spindle orientation remains controversial, hence there is considerable interest in understanding how neural progenitor cell mitosis is controlled during neurogenesis. We discovered that Treacle, which is encoded by the Tcof1 gene, is a novel centrosome- and kinetochore-associated protein that is critical for spindle fidelity and mitotic progression. Tcof1/Treacle loss-of-function disrupts spindle orientation and cell cycle progression, which perturbs the maintenance, proliferation, and localization of neural progenitors during cortical neurogenesis. Consistent with this, Tcof1(+/- mice exhibit reduced brain size as a consequence of defects in neural progenitor maintenance. We determined that Treacle elicits its effect via a direct interaction with Polo-like kinase1 (Plk1, and furthermore we discovered novel in vivo roles for Plk1 in governing mitotic progression and spindle orientation in the developing mammalian cortex. Increased asymmetric cell division, however, did not promote increased neuronal differentiation. Collectively our research has therefore identified Treacle and Plk1 as novel in vivo regulators of spindle fidelity, mitotic progression, and proliferation in the maintenance and localization of neural progenitor cells. Together, Treacle and Plk1 are critically required for proper cortical neurogenesis, which has important implications in the regulation of mammalian brain size and the pathogenesis of congenital neurodevelopmental disorders such as microcephaly.

  8. Investigation of the role of four mitotic septins and chitin synthase 2 for cytokinesis in Kluyveromyces lactis.

    Science.gov (United States)

    Rippert, Dorthe; Heinisch, Jürgen J

    2016-09-01

    Septins are key components of the cell division machinery from yeast to humans. The model yeast Saccharomyces cerevisiae has five mitotic septins, Cdc3, Cdc10, Cdc11, Cdc12, and Shs1. Here we characterized the five orthologs from the genetically less-redundant milk yeast Kluyveromyces lactis. We found that except for KlSHS1 all septin genes are essential. Klshs1 deletions displayed temperature-sensitive growth and morphological defects. Heterologous complementation analyses revealed that all five K. lactis genes encode functional orthologs of their S. cerevisiae counterparts. Fluorophore-tagged versions of the K. lactis septins localized to a ring at the incipient bud site and split into two separate rings at the bud neck later in cytokinesis. One of the key proteins recruited to the bud neck by septins in S. cerevisiae is the chitin synthase Chs2, which synthesizes the primary septum. KlCHS2 was found to be essential and deletions showed cytokinetic defects upon spore germination. KlChs2-GFP also localized to the bud neck and to punctate structures in K. lactis. We conclude that cytokinesis in K. lactis is similar to S. cerevisiae and chimeric septin complexes are fully functional in both yeasts. In contrast to some S. cerevisiae strains, KlChs2 and KlCdc10 were found to be essential. PMID:27422440

  9. Inhibition of Plk1 and Cyclin B1 expression results in panobinostat-induced G₂ delay and mitotic defects.

    Science.gov (United States)

    Prystowsky, Michael; Feeney, Katherine; Kawachi, Nicole; Montagna, Cristina; Willmott, Michelle; Wasson, Christopher; Antkowiak, Maciej; Loudig, Olivier; Parish, Joanna

    2013-01-01

    The development of clinically useful histone deacetylase inhibitors has expanded greatly. In a preclinical study, we showed that panobinostat (LBH589) inhibits cell cycle progression of human head and neck squamous cell carcinoma (HNSCC) cell lines at G₂/M and an associated decrease in expression of particular genes required for passage through G₂ and mitosis. In this study we sought to analyse the mechanistic underpinnings of panobinostat-induced growth arrest. HNSCC cell lines were synchronised and progression through mitosis monitored. We demonstrate that panobinostat causes a marked G₂ delay and mitotic defects. A loss of G₂-specific Plk1 and Cyclin B1 expression and co-incident increase in p21(Waf1/Cip1) expression is also shown. Furthermore, we show a significant loss of E2F1 recruitment to the promoters of these genes in response to panobinostat treatment. These data provide mechanistic evidence of panobinostat-induced cell cycle arrest and highlight its potential as a chemotherapeutic agent for HNSCC.

  10. 人类1号染色体可变剪接与普通剪接基因同义密码子的使用分析I.同义密码子偏爱使用分析%Synonymous Codon Usage of Both Alternatively and Commonly Spliced Genes in Human Chromosome 1 I:Synonymous Codon Usage Bias Analysis

    Institute of Scientific and Technical Information of China (English)

    陈学平; 武耀廷; 郭家明; 张成; 马飞

    2004-01-01

    It is already clear that alternative splicing has an extremely important role in expanding the protein diversity. Comparative study of the codon usage patterns of alternatively and commonly spliced genes may thereby be necessary. In this paper, the patterns of codon usage bias of two kinds of human genes, alternatively spliced genes and commonly spliced genes, were formulated through analyzing 344 non-redundant protein coding sequences from alternatively spliced genes (188183 codons) and 386 from commonly spliced genes (223116 codons) in human chromosome 1. Overall codon usage data analysis indicated that the alternatively spliced genes showed a stronger codon usage bias than commonly spliced genes. Very extensive heterogeneity of G+C content in silent third codon position (GC3s) was evident among these genes, and GC3s content of alternatively spliced genes was higher than that of commonly spliced genes. G- or C-ending codons were more abundant in alternatively spliced genes than commonly spliced genes in human chromosome 1. The causation of differences created could be explained by pre-mRNA structural characteristics of alternatively spliced genes influencing their codon usage bias.%人类1号染色体可变剪接(选择性剪接)基因344非冗余蛋白质编码序列(188183密码子)和普通剪接(非可变剪接)基因的386蛋白质编码序列(223116密码子)被用于研究人类密码子使用偏爱模式.全部密码子使用数据分析表明,人类可变剪接基因密码子的偏爱水平显著高于普通剪接基因.在人类1号染色体基因中,密码子第三位置的G+C含量有很大的异质性(0.24~0.95),并且可变剪接基因密码子第三位置平均G+C含量(64.66%)大于普通剪接基因(59.97%).Nc值对GC3s图显示密码子偏爱使用除了受核苷酸组成制约外,其它的因子可能也影响密码子的使用变化.此外,可变剪接基因中以G 或C结尾的密码子比普通剪接基因出现的频率高.密码子使

  11. The Ki-67 and RepoMan mitotic phosphatases assemble via an identical, yet novel mechanism.

    Science.gov (United States)

    Kumar, Ganesan Senthil; Gokhan, Ezgi; De Munter, Sofie; Bollen, Mathieu; Vagnarelli, Paola; Peti, Wolfgang; Page, Rebecca

    2016-01-01

    Ki-67 and RepoMan have key roles during mitotic exit. Previously, we showed that Ki-67 organizes the mitotic chromosome periphery and recruits protein phosphatase 1 (PP1) to chromatin at anaphase onset, in a similar manner as RepoMan (Booth et al., 2014). Here we show how Ki-67 and RepoMan form mitotic exit phosphatases by recruiting PP1, how they distinguish between distinct PP1 isoforms and how the assembly of these two holoenzymes are dynamically regulated by Aurora B kinase during mitosis. Unexpectedly, our data also reveal that Ki-67 and RepoMan bind PP1 using an identical, yet novel mechanism, interacting with a PP1 pocket that is engaged only by these two PP1 regulators. These findings not only show how two distinct mitotic exit phosphatases are recruited to their substrates, but also provide immediate opportunities for the design of novel cancer therapeutics that selectively target the Ki-67:PP1 and RepoMan:PP1 holoenzymes. PMID:27572260

  12. The selective inhibition of protein phosphatase-1 results in mitotic catastrophe and impaired tumor growth.

    Science.gov (United States)

    Winkler, Claudia; De Munter, Sofie; Van Dessel, Nele; Lesage, Bart; Heroes, Ewald; Boens, Shannah; Beullens, Monique; Van Eynde, Aleyde; Bollen, Mathieu

    2015-12-15

    The serine/threonine protein phosphatase-1 (PP1) complex is a key regulator of the cell cycle. However, the redundancy of PP1 isoforms and the lack of specific inhibitors have hampered studies on the global role of PP1 in cell cycle progression in vertebrates. Here, we show that the overexpression of nuclear inhibitor of PP1 (NIPP1; also known as PPP1R8) in HeLa cells culminated in a prometaphase arrest, associated with severe spindle-formation and chromosome-congression defects. In addition, the spindle assembly checkpoint was activated and checkpoint silencing was hampered. Eventually, most cells either died by apoptosis or formed binucleated cells. The NIPP1-induced mitotic arrest could be explained by the inhibition of PP1 that was titrated away from other mitotic PP1 interactors. Consistent with this notion, the mitotic-arrest phenotype could be rescued by the overexpression of PP1 or the inhibition of the Aurora B kinase, which acts antagonistically to PP1. Finally, we demonstrate that the overexpression of NIPP1 also hampered colony formation and tumor growth in xenograft assays in a PP1-dependent manner. Our data show that the selective inhibition of PP1 can be used to induce cancer cell death through mitotic catastrophe. PMID:26542020

  13. Classification of mitotic figures with convolutional neural networks and seeded blob features

    Directory of Open Access Journals (Sweden)

    Christopher D Malon

    2013-01-01

    Full Text Available Background: The mitotic figure recognition contest at the 2012 International Conference on Pattern Recognition (ICPR challenges a system to identify all mitotic figures in a region of interest of hematoxylin and eosin stained tissue, using each of three scanners (Aperio, Hamamatsu, and multispectral. Methods: Our approach combines manually designed nuclear features with the learned features extracted by convolutional neural networks (CNN. The nuclear features capture color, texture, and shape information of segmented regions around a nucleus. The use of a CNN handles the variety of appearances of mitotic figures and decreases sensitivity to the manually crafted features and thresholds. Results : On the test set provided by the contest, the trained system achieves F1 scores up to 0.659 on color scanners and 0.589 on multispectral scanner. Conclusions : We demonstrate a powerful technique combining segmentation-based features with CNN, identifying the majority of mitotic figures with a fair precision. Further, we show that the approach accommodates information from the additional focal planes and spectral bands from a multi-spectral scanner without major redesign.

  14. Hsp70 protects mitotic cells against heat-induced centrosome damage and division abnormalities

    NARCIS (Netherlands)

    Hut, HMJ; Kampinga, HH; Sibon, OCM

    2005-01-01

    The effect of heat shock on centrosomes has been mainly studied in interphase cells. Centrosomes play a key role in proper segregation of DNA during mitosis. However, the direct effect and consequences of heat shock on mitotic cells and a possible cellular defense system against proteotoxic stress d

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

    DEFF Research Database (Denmark)

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

    1994-01-01

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

  16. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-01-03

    Highlights: •NuMA is modified by SUMO-1 in a cell cycle-dependent manner. •NuMA lysine 1766 is the primary target site for SUMOylation. •SUMOylation-deficient NuMA induces multiple spindle poles during mitosis. •SUMOylated NuMA induces microtubule bundling. -- Abstract: Covalent conjugation of proteins with small ubiquitin-like modifier 1 (SUMO-1) plays a critical role in a variety of cellular functions including cell cycle control, replication, and transcriptional regulation. Nuclear mitotic apparatus protein (NuMA) localizes to spindle poles during mitosis, and is an essential component in the formation and maintenance of mitotic spindle poles. Here we show that NuMA is a target for covalent conjugation to SUMO-1. We find that the lysine 1766 residue is the primary NuMA acceptor site for SUMO-1 conjugation. Interestingly, SUMO modification of endogenous NuMA occurs at the entry into mitosis and this modification is reversed after exiting from mitosis. Knockdown of Ubc9 or forced expression of SENP1 results in impairment of the localization of NuMA to mitotic spindle poles during mitosis. The SUMOylation-deficient NuMA mutant is defective in microtubule bundling, and multiple spindles are induced during mitosis. The mitosis-dependent dynamic SUMO-1 modification of NuMA might contribute to NuMA-mediated formation and maintenance of mitotic spindle poles during mitosis.

  18. Influence of sodium phosphate (E 339) on mitotic division in Calendula officinalis L.

    OpenAIRE

    Romeo-Cristian Marc; Gabriela Capraru

    2008-01-01

    This paper includes the cytogenetic effects induced by sodium phosphate (E 339) food additive in meristematic cells of Calendula officinalis L. root tips. The increase of food additive concentration determined the decrease of mitotic index, while the frequency and the type of chromosome aberrations are much greater in treated variants, comparatively with control.

  19. Observer reliability in assessment of mitotic activity and MIB-1-determined proliferation rate in pediatric sarcomas

    NARCIS (Netherlands)

    Molenaar, W M; Plaat, B E; Berends, E R; te Meerman, G J

    2000-01-01

    In hematoxylin-eosin-stained sections of 20 pediatric sarcomas the mitotic index was assessed by four experienced pathologists and four less-experienced observers without prior instructions. In adjacent sections immunolabeled for MIB-1, the proliferation index was assessed as the estimated percentag

  20. A mitotic SKAP isoform regulates spindle positioning at astral microtubule plus ends.

    Science.gov (United States)

    Kern, David M; Nicholls, Peter K; Page, David C; Cheeseman, Iain M

    2016-05-01

    The Astrin/SKAP complex plays important roles in mitotic chromosome alignment and centrosome integrity, but previous work found conflicting results for SKAP function. Here, we demonstrate that SKAP is expressed as two distinct isoforms in mammals: a longer, testis-specific isoform that was used for the previous studies in mitotic cells and a novel, shorter mitotic isoform. Unlike the long isoform, short SKAP rescues SKAP depletion in mitosis and displays robust microtubule plus-end tracking, including localization to astral microtubules. Eliminating SKAP microtubule binding results in severe chromosome segregation defects. In contrast, SKAP mutants specifically defective for plus-end tracking facilitate proper chromosome segregation but display spindle positioning defects. Cells lacking SKAP plus-end tracking have reduced Clasp1 localization at microtubule plus ends and display increased lateral microtubule contacts with the cell cortex, which we propose results in unbalanced dynein-dependent cortical pulling forces. Our work reveals an unappreciated role for the Astrin/SKAP complex as an astral microtubule mediator of mitotic spindle positioning. PMID:27138257

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

    Science.gov (United States)

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

    2012-01-01

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

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

    Science.gov (United States)

    Salmela, Anna-Leena; Pouwels, Jeroen; Kukkonen-Macchi, Anu; Waris, Sinikka; Toivonen, Pauliina; Jaakkola, Kimmo; Mäki-Jouppila, Jenni; Kallio, Lila; Kallio, Marko J

    2012-03-10

    The spindle assembly checkpoint (SAC) is a conserved mechanism that ensures the fidelity of chromosome distribution in mitosis by preventing anaphase onset until the correct bipolar microtubule-kinetochore attachments are formed. Errors in SAC function may contribute to tumorigenesis by inducing numerical chromosome anomalies (aneuploidy). On the other hand, total disruption of SAC can lead to massive genomic imbalance followed by cell death, a phenomena that has therapeutic potency. We performed a cell-based high-throughput screen with a compound library of 2000 bioactives for novel SAC inhibitors and discovered a plant-derived phenolic compound eupatorin (3',5-dihydroxy-4',6,7-trimethoxyflavone) as an anti-mitotic flavonoid. The premature override of the microtubule drug-imposed mitotic arrest by eupatorin is dependent on microtubule-kinetochore attachments but not interkinetochore tension. Aurora B kinase activity, which is essential for maintenance of normal SAC signaling, is diminished by eupatorin in cells and in vitro providing a mechanistic explanation for the observed forced mitotic exit. Eupatorin likely has additional targets since eupatorin treatment of pre-mitotic cells causes spindle anomalies triggering a transient M phase delay followed by impaired cytokinesis and polyploidy. Finally, eupatorin potently induces apoptosis in multiple cancer cell lines and suppresses cancer cell proliferation in organotypic 3D cell culture model.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-03-10

    The spindle assembly checkpoint (SAC) is a conserved mechanism that ensures the fidelity of chromosome distribution in mitosis by preventing anaphase onset until the correct bipolar microtubule-kinetochore attachments are formed. Errors in SAC function may contribute to tumorigenesis by inducing numerical chromosome anomalies (aneuploidy). On the other hand, total disruption of SAC can lead to massive genomic imbalance followed by cell death, a phenomena that has therapeutic potency. We performed a cell-based high-throughput screen with a compound library of 2000 bioactives for novel SAC inhibitors and discovered a plant-derived phenolic compound eupatorin (3 Prime ,5-dihydroxy-4 Prime ,6,7-trimethoxyflavone) as an anti-mitotic flavonoid. The premature override of the microtubule drug-imposed mitotic arrest by eupatorin is dependent on microtubule-kinetochore attachments but not interkinetochore tension. Aurora B kinase activity, which is essential for maintenance of normal SAC signaling, is diminished by eupatorin in cells and in vitro providing a mechanistic explanation for the observed forced mitotic exit. Eupatorin likely has additional targets since eupatorin treatment of pre-mitotic cells causes spindle anomalies triggering a transient M phase delay followed by impaired cytokinesis and polyploidy. Finally, eupatorin potently induces apoptosis in multiple cancer cell lines and suppresses cancer cell proliferation in organotypic 3D cell culture model.

  4. Gauchos and ochos: a Wee1-Cdk tango regulating mitotic entry

    Directory of Open Access Journals (Sweden)

    Enders Greg H

    2010-05-01

    Full Text Available Abstract The kinase Wee1 has been recognized for a quarter century as a key inhibitor of Cyclin dependent kinase 1 (Cdk1 and mitotic entry in eukaryotes. Nonetheless, Wee1 regulation is not well understood and its large amino-terminal regulatory domain (NRD has remained largely uncharted. Evidence has accumulated that cyclin B/Cdk1 complexes reciprocally inhibit Wee1 activity through NRD phosphorylation. Recent studies have identified the first functional NRD elements and suggested that vertebrate cyclin A/Cdk2 complexes also phosphorylate the NRD. A short NRD peptide, termed the Wee box, augments the activity of the Wee1 kinase domain. Cdk1/2-mediated phosphorylation of the Wee box (on T239 antagonizes kinase activity. A nearby region harbors a conserved RxL motif (RxL1 that promotes cyclin A/Cdk2 binding and T239 phosphorylation. Mutation of either T239 or RxL1 bolsters the ability of Wee1 to block mitotic entry, consistent with negative regulation of Wee1 through these sites. The region in human somatic Wee1 that encompasses RxL1 also binds Crm1, directing Wee1 export from the nucleus. These studies have illuminated important aspects of Wee1 regulation and defined a specific molecular pathway through which cyclin A/Cdk2 complexes foster mitotic entry. The complexity, speed, and importance of regulation of mitotic entry suggest that there is more to be learned.

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

    Directory of Open Access Journals (Sweden)

    Victor I. Popov

    2011-01-01

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

  6. Tests for sex-biased dispersal using bi-parentally inherited genetic markers.

    OpenAIRE

    Goudet J.; Perrin N.; Waser P.

    2002-01-01

    Understanding why dispersal is sex-biased in many taxa is still a major concern in evolutionary ecology. Dispersal tends to be male-biased in mammals and female-biased in birds, but counter-examples exist and little is known about sex bias in other taxa. Obtaining accurate measures of dispersal in the field remains a problem. Here we describe and compare several methods for detecting sex-biased dispersal using bi-parentally inherited, codominant genetic markers. If gene flow is restricted amo...

  7. Codon Bias and Mutability in HIV Sequences

    CERN Document Server

    Waelbroeck, H

    1997-01-01

    A survey of the patterns of synonymous codon preferences in the HIV env gene reveals a relation between the codon bias and the mutability requirements in different regions in the protein. At hypervariable regions in $gp120$, one finds a greater proportion of codons that tend to mutate non-synonymously, but to a target that is similar in hydrophobicity and volume. We argue that this strategy results from a compromise between the selective pressure placed on the virus by the induced immune response, which favours amino acid substitutions in the complementarity determining regions, and the negative selection against missense mutations that violate structural constraints of the env protein.

  8. Cellular and molecular effects of 1GeV/n iron ion exposure on post-mitotic human neurons

    Science.gov (United States)

    Guida, Peter; Vazquez, Marcelo E.; Guida, Peter; Kim, Angela

    During space travel, astronauts will be exposed to high energy, high atomic number (HZE) radiation. The potential for damage to cells of the central nervous system following exposure to HZE particle radiation has been characterized as a potential critical risk. Unfortunately, there are very few working model systems of human neurons and as a result, data describing the effects of HZE radiation on them is scarce. To begin risk assessment studies, we utilized an in vitro model consisting of terminally differentiated, post-mitotic human neurons (hNT cells). Previous studies have shown that transplantation of these cells into numerous rodent models of neurological diseases has resulted in successful mitigation of the related disorders, thereby demonstrating their functional relevance. Following exposure of these cells to 1GeV/n Fe ions at the NASA Space Radiation Laboratory, we measured the induction and repair of DNA damage (as revealed by g-H2AX foci), cytotoxicity, gene expression changes, and the induction of apoptosis and its pharmacological reduction. Fluorescence microscopy techniques revealed that there was a dose-dependent induction of g- H2AX foci in hNT cells, with a peak effect 4 hours after exposure (which is significantly longer than for reports using mitotic cells). DNA repair was evident in that the levels of g-H2AX foci were reduced to those in unirradiated cells by 24 hours post-irradiation. Cytotoxicity was also induced in a dose-dependent manner as detected by the fluorescent-based Live/Dead assay. Analysis of the status of the apoptosis-inducing gene p53 showed that the levels of this protein increased significantly 4-8 hours after exposure to Fe ions. By 3 days post-irradiation, annexin V staining demonstrated a dose-dependent induction of apoptosis in the hNT cells. Pre-treatment with two different concentrations of the growth factor TGF-b were effective in reducing the levels of Fe ion-induced apoptosis to statistically significant degrees.

  9. Administrative bias in South Africa

    Directory of Open Access Journals (Sweden)

    E S Nwauche

    2005-01-01

    Full Text Available This article reviews the interpretation of section 6(2(aii of the Promotion of Administrative Justice Act which makes an administrator “biased or reasonably suspected of bias” a ground of judicial review. In this regard, the paper reviews the determination of administrative bias in South Africa especially highlighting the concept of institutional bias. The paper notes that inspite of the formulation of the bias ground of review the test for administrative bias is the reasonable apprehension test laid down in the case of President of South Africa v South African Rugby Football Union(2 which on close examination is not the same thing. Accordingly the paper urges an alternative interpretation that is based on the reasonable suspicion test enunciated in BTR Industries South Africa (Pty Ltd v Metal and Allied Workers Union and R v Roberts. Within this context, the paper constructs a model for interpreting the bias ground of review that combines the reasonable suspicion test as interpreted in BTR Industries and R v Roberts, the possibility of the waiver of administrative bias, the curative mechanism of administrative appeal as well as some level of judicial review exemplified by the jurisprudence of article 6(1 of the European Convention of Human Rights, especially in the light of the contemplation of the South African Magistrate Court as a jurisdictional route of judicial review.

  10. Cognitive Bias in Systems Verification

    Science.gov (United States)

    Larson, Steve

    2012-01-01

    Working definition of cognitive bias: Patterns by which information is sought and interpreted that can lead to systematic errors in decisions. Cognitive bias is used in diverse fields: Economics, Politics, Intelligence, Marketing, to name a few. Attempts to ground cognitive science in physical characteristics of the cognitive apparatus exceed our knowledge. Studies based on correlations; strict cause and effect is difficult to pinpoint. Effects cited in the paper and discussed here have been replicated many times over, and appear sound. Many biases have been described, but it is still unclear whether they are all distinct. There may only be a handful of fundamental biases, which manifest in various ways. Bias can effect system verification in many ways . Overconfidence -> Questionable decisions to deploy. Availability -> Inability to conceive critical tests. Representativeness -> Overinterpretation of results. Positive Test Strategies -> Confirmation bias. Debiasing at individual level very difficult. The potential effect of bias on the verification process can be managed, but not eliminated. Worth considering at key points in the process.

  11. Gender bias in academic recruitment

    DEFF Research Database (Denmark)

    Abramo, Giovanni; D’Angelo, Ciriaco Andrea; Rosati, Francesco

    2016-01-01

    It is well known that women are underrepresented in the academic systems of many countries. Gender discrimination is one of the factors that could contribute to this phenomenon. This study considers a recent national academic recruitment campaign in Italy, examining whether women are subject...... to more or less bias than men. The findings show that no gender-related differences occur among the candidates who benefit from positive bias, while among those candidates affected by negative bias, the incidence of women is lower than that of men. Among the factors that determine success in a competition...

  12. Performance of 181 chemicals in a Drosophila assay predominantly monitoring interchromosomal mitotic recombination.

    Science.gov (United States)

    Vogel, E W; Nivard, M J

    1993-01-01

    An evaluation is presented of the effects of 181 chemicals in the (white/white+) (w/w+) eye mosaic assay, an in vivo short-term test measuring genetic damage in somatic cells of Drosophila after treatment of larvae. The genetic principle of this system is loss of heterozygosity for the wild-type reporter gene w+, an event predominantly resulting from homologous interchromosomal mitotic recombination between the two X chromosomes of female genotypes. The w/w+ eye mosaic test detects a broad spectrum of DNA modifications, since all distinct classes of genotoxins are monitored. Non-DNA-reactive chemicals are in principle not detected by this system. Occasional positive responses obtained for chemicals such as amitrole, ethionine and hexachloeroethane are probably not related to the mechanism responsible for their tumorigenicity. The principle outcome of this analysis is the necessity for classification of responses into three categories. (i) Positive, '++'. The 92 chemicals (Tables II and III) falling into this category were clearly recombinagenic in the assay, meaning that dose-response relations were obtained (or could have been established as was evident from the strong responses obtained at one or two exposure doses). Among the 92 chemicals were 49 promutagens including volatile chemicals such as vinyl bromide and vinyl chloride. (ii) Marginally positive, '+w'. The definition of a weakly positive response is the absence of a dose-response relationship due to the fact that a weak but reproducible effect, in most cases no more than a doubling of the spontaneous clone frequency, is inherently related to toxicity. The 40 chemicals (Tables IV and V) belonging to this category mainly represented four distinct types. (a) Procarcinogens, such as 2-acetylaminofluorene, dibenz[a,h]anthracene, p-dimethylaminoazobenzene, 2-naphthylamine and safrole, for which metabolic conversion was the apparent problem in the assay. (b) Electrophilic chemicals of high nucleophilic

  13. Loss of function of the Drosophila Ninein-related centrosomal protein Bsg25D causes mitotic defects and impairs embryonic development.

    Science.gov (United States)

    Kowanda, Michelle; Bergalet, Julie; Wieczorek, Michal; Brouhard, Gary; Lécuyer, Éric; Lasko, Paul

    2016-01-01

    The centrosome-associated proteins Ninein (Nin) and Ninein-like protein (Nlp) play significant roles in microtubule stability, nucleation and anchoring at the centrosome in mammalian cells. Here, we investigate Blastoderm specific gene 25D (Bsg25D), which encodes the only Drosophila protein that is closely related to Nin and Nlp. In early embryos, we find that Bsg25D mRNA and Bsg25D protein are closely associated with centrosomes and astral microtubules. We show that sequences within the coding region and 3'UTR of Bsg25D mRNAs are important for proper localization of this transcript in oogenesis and embryogenesis. Ectopic expression of eGFP-Bsg25D from an unlocalized mRNA disrupts microtubule polarity in mid-oogenesis and compromises the distribution of the axis polarity determinant Gurken. Using total internal reflection fluorescence microscopy, we show that an N-terminal fragment of Bsg25D can bind microtubules in vitro and can move along them, predominantly toward minus-ends. While flies homozygous for a Bsg25D null mutation are viable and fertile, 70% of embryos lacking maternal and zygotic Bsg25D do not hatch and exhibit chromosome segregation defects, as well as detachment of centrosomes from mitotic spindles. We conclude that Bsg25D is a centrosomal protein that, while dispensable for viability, nevertheless helps ensure the integrity of mitotic divisions in Drosophila. PMID:27422905

  14. Cognitive biases and language universals

    CERN Document Server

    Baronchelli, Andrea; Puglisi, Andrea

    2013-01-01

    Language universals have been longly attributed to an innate Universal Grammar. An alternative explanation states that linguistic universals emerged independently in every language in response to shared cognitive, though non language-specific, biases. A computational model has recently shown how this could be the case, focusing on the paradigmatic example of the universal properties of color naming patterns, and producing results in accurate agreement with the experimental data. Here we investigate thoroughly the role of a cognitive bias in the framework of this model. We study how, and to what extent, the structure of the bias can influence the corresponding linguistic universal patterns. We show also that the cultural history of a group of speakers introduces population-specific constraints that act against the uniforming pressure of the cognitive bias, and we clarify the interplay between these two forces. We believe that our simulations can help to shed light on the possible mechanisms at work in the evol...

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

    DEFF Research Database (Denmark)

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

    2013-01-01

    reported to stabilize the dynamic spindle through crosslinking adjacent MTs. Mars, a novel MAP, is essential for the early development of Drosophila embryos. Previous studies showed that Mars is required for maintaining an intact mitotic spindle but did not provide a molecular mechanism for this function....... Here we show that Mars is able to stabilize the mitotic spindle in vivo. Both in vivo and in vitro data reveal that the N-terminal region of Mars functions in the stabilization of the mitotic spindle by crosslinking adjacent MTs....

  16. Analysis of tag-position bias in MPSS technology

    Directory of Open Access Journals (Sweden)

    Rattray Magnus

    2006-04-01

    Full Text Available Abstract Background Massively Parallel Signature Sequencing (MPSS technology was recently developed as a high-throughput technology for measuring the concentration of mRNA transcripts in a sample. It has previously been observed that the position of the signature tag in a transcript (distance from 3' end can affect the measurement, but this effect has not been studied in detail. Results We quantify the effect of tag-position bias in Classic and Signature MPSS technology using published data from Arabidopsis, rice and human. We investigate the relationship between measured concentration and tag-position using nonlinear regression methods. The observed relationship is shown to be broadly consistent across different data sets. We find that there exist different and significant biases in both Classic and Signature MPSS data. For Classic MPSS data, genes with tag-position in the middle-range have highest measured abundance on average while genes with tag-position in the high-range, far from the 3' end, show a significant decrease. For Signature MPSS data, high-range tag-position genes tend to have a flatter relationship between tag-position and measured abundance. Thus, our results confirm that the Signature MPSS method fixes a substantial problem with the Classic MPSS method. For both Classic and Signature MPSS data there is a positive correlation between measured abundance and tag-position for low-range tag-position genes. Compared with the effects of mRNA length and number of exons, tag-position bias seems to be more significant in Arabadopsis. The tag-position bias is reflected both in the measured abundance of genes with a significant tag count and in the proportion of unexpressed genes identified. Conclusion Tag-position bias should be taken into consideration when measuring mRNA transcript abundance using MPSS technology, both in Classic and Signature MPSS methods.

  17. Human papillomavirus type 16 E7 perturbs DREAM to promote cellular proliferation and mitotic gene expression

    OpenAIRE

    DeCaprio, James A.

    2013-01-01

    Study of the small DNA tumor viruses continues to provide valuable new insights into oncogenesis and fundamental biological processes. While much has already been revealed about how the human papillomaviruses (HPVs) can transform cells and contribute to cervical and oropharyngeal cancer, there clearly is much more to learn. In this issue of Oncogene, Pang et al. demonstrate that the high-risk HPV16 E7 oncogene can promote cellular proliferation by interacting with the DREAM (DP, RB-like, E2F ...

  18. Preferences, country bias, and international trade

    NARCIS (Netherlands)

    S. Roy (Santanu); J.M.A. Viaene (Jean-Marie)

    1998-01-01

    textabstractAnalyzes international trade where consumer preferences exhibit country bias. Why country biases arise; How trade can occur in the presence of country bias; Implication for the pattern of trade and specialization.

  19. The intentionality bias and schizotypy

    OpenAIRE

    Moore, James W.; Pope, A.

    2014-01-01

    The “intentionality bias” refers to our automatic tendency to judge other people's actions to be intentional. In this experiment we extended research on this effect in two key ways. First, we developed a novel nonlinguistic task for assessing the intentionality bias. This task used video stimuli of ambiguous movements. Second, we investigated the relationship between the strength of this bias and schizotypy (schizophrenia-like symptoms in healthy individuals). Our results showed that the inte...

  20. The estimation method of GPS instrumental biases

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A model of estimating the global positioning system (GPS) instrumental biases and the methods to calculate the relative instrumental biases of satellite and receiver are presented. The calculated results of GPS instrumental biases, the relative instrumental biases of satellite and receiver, and total electron content (TEC) are also shown. Finally, the stability of GPS instrumental biases as well as that of satellite and receiver instrumental biases are evaluated, indicating that they are very stable during a period of two months and a half.

  1. Political infants? Developmental origins of the negativity bias.

    Science.gov (United States)

    Kinzler, Katherine D; Vaish, Amrisha

    2014-06-01

    The negativity bias in human cognition emerges in infancy and continues throughout childhood. To fully understand the relationship between differences in attention to negative stimuli and variance in political ideologies, it is critical to consider human development and the process by which early individual differences in negativity unfold and are shaped by both genes and environment.

  2. Bias and design in software specifications

    Science.gov (United States)

    Straub, Pablo A.; Zelkowitz, Marvin V.

    1990-01-01

    Implementation bias in a specification is an arbitrary constraint in the solution space. Presented here is a model of bias in software specifications. Bias is defined in terms of the specification process and a classification of the attributes of the software product. Our definition of bias provides insight into both the origin and the consequences of bias. It also shows that bias is relative and essentially unavoidable. Finally, we describe current work on defining a measure of bias, formalizing our model, and relating bias to software defects.

  3. Silencing erythropoietin receptor on glioma cells reinforces efficacy of temozolomide and X-rays through senescence and mitotic catastrophe.

    Science.gov (United States)

    Pérès, Elodie A; Gérault, Aurélie N; Valable, Samuel; Roussel, Simon; Toutain, Jérôme; Divoux, Didier; Guillamo, Jean-Sébastien; Sanson, Marc; Bernaudin, Myriam; Petit, Edwige

    2015-02-10

    Hypoxia-inducible genes may contribute to therapy resistance in glioblastoma (GBM), the most aggressive and hypoxic brain tumours. It has been recently reported that erythropoietin (EPO) and its receptor (EPOR) are involved in glioma growth. We now investigated whether EPOR signalling may modulate the efficacy of the GBM current treatment based on chemotherapy (temozolomide, TMZ) and radiotherapy (X-rays). Using RNA interference, we showed on glioma cell lines (U87 and U251) that EPOR silencing induces a G2/M cell cycle arrest, consistent with the slowdown of glioma growth induced by EPOR knock-down. In vivo, we also reported that EPOR silencing combined with TMZ treatment is more efficient to delay tumour recurrence and to prolong animal survival compared to TMZ alone. In vitro, we showed that EPOR silencing not only increases the sensitivity of glioma cells to TMZ as well as X-rays but also counteracts the hypoxia-induced chemo- and radioresistance. Silencing EPOR on glioma cells exposed to conventional treatments enhances senescence and induces a robust genomic instability that leads to caspase-dependent mitotic death by increasing the number of polyploid cells and cyclin B1 expression. Overall these data suggest that EPOR could be an attractive target to overcome therapeutic resistance toward ionising radiation or temozolomide.

  4. A time-series method for automated measurement of changes in mitotic and interphase duration from time-lapse movies.

    Directory of Open Access Journals (Sweden)

    Frederic D Sigoillot

    Full Text Available BACKGROUND: Automated time-lapse microscopy can visualize proliferation of large numbers of individual cells, enabling accurate measurement of the frequency of cell division and the duration of interphase and mitosis. However, extraction of quantitative information by manual inspection of time-lapse movies is too time-consuming to be useful for analysis of large experiments. METHODOLOGY/PRINCIPAL FINDINGS: Here we present an automated time-series approach that can measure changes in the duration of mitosis and interphase in individual cells expressing fluorescent histone 2B. The approach requires analysis of only 2 features, nuclear area and average intensity. Compared to supervised learning approaches, this method reduces processing time and does not require generation of training data sets. We demonstrate that this method is as sensitive as manual analysis in identifying small changes in interphase or mitotic duration induced by drug or siRNA treatment. CONCLUSIONS/SIGNIFICANCE: This approach should facilitate automated analysis of high-throughput time-lapse data sets to identify small molecules or gene products that influence timing of cell division.

  5. The evolution of social learning rules: payoff-biased and frequency-dependent biased transmission.

    Science.gov (United States)

    Kendal, Jeremy; Giraldeau, Luc-Alain; Laland, Kevin

    2009-09-21

    Humans and other animals do not use social learning indiscriminately, rather, natural selection has favoured the evolution of social learning rules that make selective use of social learning to acquire relevant information in a changing environment. We present a gene-culture coevolutionary analysis of a small selection of such rules (unbiased social learning, payoff-biased social learning and frequency-dependent biased social learning, including conformism and anti-conformism) in a population of asocial learners where the environment is subject to a constant probability of change to a novel state. We define conditions under which each rule evolves to a genetically polymorphic equilibrium. We find that payoff-biased social learning may evolve under high levels of environmental variation if the fitness benefit associated with the acquired behaviour is either high or low but not of intermediate value. In contrast, both conformist and anti-conformist biases can become fixed when environment variation is low, whereupon the mean fitness in the population is higher than for a population of asocial learners. Our examination of the population dynamics reveals stable limit cycles under conformist and anti-conformist biases and some highly complex dynamics including chaos. Anti-conformists can out-compete conformists when conditions favour a low equilibrium frequency of the learned behaviour. We conclude that evolution, punctuated by the repeated successful invasion of different social learning rules, should continuously favour a reduction in the equilibrium frequency of asocial learning, and propose that, among competing social learning rules, the dominant rule will be the one that can persist with the lowest frequency of asocial learning. PMID:19501102

  6. Paramutation: a heritable change in gene expression by allelic interactions in trans

    NARCIS (Netherlands)

    M. Stam

    2009-01-01

    Epigenetic gene regulation involves the stable propagation of gene activity states through mitotic, and sometimes even meiotic, cell divisions without changes in DNA sequence. Paramutation is an epigenetic phenomenon involving changes in gene expression that are stably transmitted through mitosis as

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

    DEFF Research Database (Denmark)

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

    1994-01-01

    Bromodeoxyuridine (BrdUrd) labelled and unlabelled mitotic cells, respectively, can be discriminated from interphase cells using a new method, based on immunocytochemical staining of BrdUrd and flow cytometric four-parameter analysis of DNA content, BrdUrd incorporation, and forward and orthogonal...... light scatter. The method was optimized using the human leukemia cell lines HL-60 and K-562. Samples of 10(5) ethanol-fixed cells were treated with pepsin/HCl and stained as a nuclear suspension with anti-BrdUrd antibody, FITC-conjugated secondary antibody, and propidium iodide. Labelled mitoses could...... fluorescence distribution. This interpretation was supported by experiments using mitotic arrest, fluorescence activated cell sorting and microscopy, and comparison with an alternative flow cytometric method for discrimination of mitoses....

  8. Mitotic stopwatch for the blast fungus Magnaporthe oryzae during invasion of rice cells.

    Science.gov (United States)

    Jones, Kiersun; Jenkinson, Cory B; Borges Araújo, Maíra; Zhu, Jie; Kim, Rebecca Y; Kim, Dong Won; Khang, Chang Hyun

    2016-08-01

    To study nuclear dynamics of Magnaporthe oryzae, we developed a novel mitotic reporter strain with GFP-NLS (localized in nuclei during interphase but in the cytoplasm during mitosis) and H1-tdTomato (localized in nuclei throughout the cell cycle). Time-lapse confocal microscopy of the reporter strain during host cell invasion provided several new insights into nuclear division and migration in M. oryzae: (i) mitosis lasts about 5min; (ii) mitosis is semi-closed; (iii) septal pores are closed during mitosis; and (iv) a nucleus exhibits extreme constriction (approximately from 2μm to 0.5μm), elongation (over 5μm), and long migration (over 16μm). Our observations raise new questions about mechanisms controlling the mitotic dynamics, and the answers to these questions may result in new means to prevent fungal proliferation without negatively affecting the host cell cycle. PMID:27321562

  9. The CUL3-KLHL18 ligase regulates mitotic entry and ubiquitylates Aurora-A.

    Science.gov (United States)

    Moghe, Saili; Jiang, Fei; Miura, Yoshie; Cerny, Ronald L; Tsai, Ming-Ying; Furukawa, Manabu

    2012-02-15

    The cullin-RING family of ubiquitin ligases regulates diverse cellular functions, such as cell cycle control, via ubiquitylation of specific substrates. CUL3 targets its substrates through BTB proteins. Here we show that depletion of CUL3 and the BTB protein KLHL18 causes a delay in mitotic entry. Centrosomal activation of Aurora-A, a kinase whose activity is required for entry into mitosis, is also delayed in depleted cells. Moreover, we identify Aurora-A as a KLHL18-interacting partner. Overexpression of KLHL18 and CUL3 promotes Aurora-A ubiquitylation in vivo, and the CUL3-KLHL18-ROC1 ligase ubiquitylates Aurora-A in vitro. Our study reveals that the CUL3-KLHL18 ligase is required for timely entry into mitosis, as well as for the activation of Aurora-A at centrosomes. We propose that the CUL3-KLHL18 ligase regulates mitotic entry through an Aurora-A-dependent pathway.

  10. The CUL3-KLHL18 ligase regulates mitotic entry and ubiquitylates Aurora-A

    Directory of Open Access Journals (Sweden)

    Saili Moghe

    2012-02-01

    The cullin-RING family of ubiquitin ligases regulates diverse cellular functions, such as cell cycle control, via ubiquitylation of specific substrates. CUL3 targets its substrates through BTB proteins. Here we show that depletion of CUL3 and the BTB protein KLHL18 causes a delay in mitotic entry. Centrosomal activation of Aurora-A, a kinase whose activity is required for entry into mitosis, is also delayed in depleted cells. Moreover, we identify Aurora-A as a KLHL18-interacting partner. Overexpression of KLHL18 and CUL3 promotes Aurora-A ubiquitylation in vivo, and the CUL3-KLHL18-ROC1 ligase ubiquitylates Aurora-A in vitro. Our study reveals that the CUL3-KLHL18 ligase is required for timely entry into mitosis, as well as for the activation of Aurora-A at centrosomes. We propose that the CUL3-KLHL18 ligase regulates mitotic entry through an Aurora-A-dependent pathway.

  11. Mitotic fidelity requires transgenerational action of a testis-restricted HP1.

    Science.gov (United States)

    Levine, Mia T; Vander Wende, Helen M; Malik, Harmit S

    2015-07-07

    Sperm-packaged DNA must undergo extensive reorganization to ensure its timely participation in embryonic mitosis. Whereas maternal control over this remodeling is well described, paternal contributions are virtually unknown. In this study, we show that Drosophila melanogaster males lacking Heterochromatin Protein 1E (HP1E) sire inviable embryos that undergo catastrophic mitosis. In these embryos, the paternal genome fails to condense and resolve into sister chromatids in synchrony with the maternal genome. This delay leads to a failure of paternal chromosomes, particularly the heterochromatin-rich sex chromosomes, to separate on the first mitotic spindle. Remarkably, HP1E is not inherited on mature sperm chromatin. Instead, HP1E primes paternal chromosomes during spermatogenesis to ensure faithful segregation post-fertilization. This transgenerational effect suggests that maternal control is necessary but not sufficient for transforming sperm DNA into a mitotically competent pronucleus. Instead, paternal action during spermiogenesis exerts post-fertilization control to ensure faithful chromosome segregation in the embryo.

  12. Mitotic Exit Function of Polo-like Kinase Cdc5 Is Dependent on Sequential Activation by Cdk1

    Directory of Open Access Journals (Sweden)

    Jose-Antonio Rodriguez-Rodriguez

    2016-05-01

    Full Text Available To complete mitosis, Saccharomyces cerevisiae needs to activate the mitotic phosphatase Cdc14. Two pathways contribute to Cdc14 regulation: FEAR (Cdc14 early anaphase release and MEN (mitotic exit network. Cdc5 polo-like kinase was found to be an important mitotic exit component. However, its specific role in mitotic exit regulation and its involvement in Cdc14 release remain unclear. Here, we provide insight into the mechanism by which Cdc5 contributes to the timely release of Cdc14. Our genetic and biochemical data indicate that Cdc5 acts in parallel with MEN during anaphase. This MEN-independent Cdc5 function requires active separase and activation by Cdk1-dependent phosphorylation. Cdk1 first phosphorylates Cdc5 to activate it in early anaphase, and then, in late anaphase, further phosphorylation of Cdc5 by Cdk1 is needed to promote its MEN-related functions.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-10-10

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

  14. Comparison of the protective action of glutathione and cysteamine on radiation-induced mitotic delay in cultured S-5 cells.

    Science.gov (United States)

    Kawasaki, S; Kobayashi, M; Hashimoto, H; Nakanishi, T

    1979-06-01

    The protective effect of glutathione (GSH) and cysteamine (MEA) on radiation-induced mitotic delay in cultured mammalian L-5 cells was studied. Cells treated with 20 mM of GSH during irradiation with 2 Gy (200 rad) showed faster recovery of the mitotic index than control cells irradiated without chemical treatment; however, GSH had no effect on mitotic delay time. Inhibition of mitosis was observed with 80, 100, and 120 mM of GSH. Cells treated with 5 mM of MEA during irradiation also showed faster recovery of the mitotic index than the controls, but in addition the delay time was shortened. Progression of G2-phase cells treated with 5-fluorouracil to mitosis after irradiation was protected by MEA but not by GSH. Progression of S-phase cells labeled with 3H-thymidine to mitosis was accelerated by both agents during irradiation.

  15. The forces that center the mitotic spindle in the C. elegans embryo

    OpenAIRE

    Garzon-Coral, Carlos

    2015-01-01

    The precise positioning of the mitotic spindle to the cell center during mitosis is a fundamental process for chromosome segregation and the division plane definition. Despite its importance, the mechanism for spindle centering remains elusive. To study this mechanism, the dynamic of the microtubules was characterized at the bulk and at the cortex in the C. elegans embryo. Then, this dynamic was correlated to the centering forces of the spindle that were studied by applying calibrated magneti...

  16. Mitotic Spindle Positioning in Saccharomyces cerevisiae Is Accomplished by Antagonistically Acting Microtubule Motor Proteins

    OpenAIRE

    Cottingham, Frank R.; Hoyt, M. Andrew

    1997-01-01

    Proper positioning of the mitotic spindle is often essential for cell division and differentiation processes. The asymmetric cell division characteristic of budding yeast, Saccharomyces cerevisiae, requires that the spindle be positioned at the mother–bud neck and oriented along the mother–bud axis. The single dynein motor encoded by the S. cerevisiae genome performs an important but nonessential spindle-positioning role. We demonstrate that kinesin-related Kip3p makes a major contribution to...

  17. Costunolide causes mitotic arrest and enhances radiosensitivity in human hepatocellular carcinoma cells

    International Nuclear Information System (INIS)

    This work aimed to investigate the effect of costunolide, a sesquiterpene lactone isolated from Michelia compressa, on cell cycle distribution and radiosensitivity of human hepatocellular carcinoma (HCC) cells. The assessment used in this study included: cell viability assay, cell cycle analysis by DNA histogram, expression of phosphorylated histone H3 (Ser 10) by flow cytometer, mitotic index by Liu's stain and morphological observation, mitotic spindle alignment by immunofluorescence of alpha-tubulin, expression of cell cycle-related proteins by Western blotting, and radiation survival by clonogenic assay. Our results show that costunolide reduced the viability of HA22T/VGH cells. It caused a rapid G2/M arrest at 4 hours shown by DNA histogram. The increase in phosphorylated histone H3 (Ser 10)-positive cells and mitotic index indicates costunolide-treated cells are arrested at mitosis, not G2, phase. Immunofluorescence of alpha-tubulin for spindle formation further demonstrated these cells are halted at metaphase. Costunolide up-regulated the expression of phosphorylated Chk2 (Thr 68), phosphorylated Cdc25c (Ser 216), phosphorylated Cdk1 (Tyr 15) and cyclin B1 in HA22T/VGH cells. At optimal condition causing mitotic arrest, costunolide sensitized HA22T/VGH HCC cells to ionizing radiation with sensitizer enhancement ratio up to 1.9. Costunolide could reduce the viability and arrest cell cycling at mitosis in hepatoma cells. Logical exploration of this mitosis-arresting activity for cancer therapeutics shows costunolide enhanced the killing effect of radiotherapy against human HCC cells

  18. Interaction of the Betapapillomavirus E2 Tethering Protein with Mitotic Chromosomes▿

    OpenAIRE

    Sekhar, Vandana; Reed, Shawna C.; Alison A McBride

    2009-01-01

    During persistent papillomavirus infection, the viral E2 protein tethers the viral genome to the host cell chromosomes, ensuring maintenance and segregation of the viral genome during cell division. However, E2 proteins from different papillomaviruses interact with distinct chromosomal regions and targets. The tethering mechanism has been best characterized for bovine papillomavirus type 1 (BPV1), where the E2 protein tethers the viral genome to mitotic chromosomes in complex with the cellula...

  19. Mitotic Kinesin-Like Protein 2 Binds and Colocalizes with Papillomavirus E2 during Mitosis▿

    OpenAIRE

    Yu, Ting; Peng, Yu-Cai; Androphy, Elliot J.

    2006-01-01

    MKlp2 is a kinesin-like motor protein of the central mitotic spindle required for completion of cytokinesis. Papillomavirus E2 is a sequence specific DNA binding protein that regulates viral transcription and replication and is responsible for partitioning viral episomes into daughter cells during cell division. We demonstrate that MKlp2 specifically associates with the E2 protein during mitosis. Using chromatin immunoprecipitation, we show viral genomes are in complex with MKlp2 only within ...

  20. c-Mos forces the mitotic cell cycle to undergo meiosis II to produce haploid gametes

    OpenAIRE

    Tachibana, Kazunori; Tanaka, Daisuke; Isobe, Tomohiro; Kishimoto, Takeo

    2000-01-01

    The meiotic cycle reduces ploidy through two consecutive M phases, meiosis I and meiosis II, without an intervening S phase. To maintain ploidy through successive generations, meiosis must be followed by mitosis after the recovery of diploidy by fertilization. However, the coordination from meiotic to mitotic cycle is still unclear. Mos, the c-mos protooncogene product, is a key regulator of meiosis in vertebrates. In contrast to the previous observation that Mos f...

  1. Costunolide causes mitotic arrest and enhances radiosensitivity in human hepatocellular carcinoma cells

    Directory of Open Access Journals (Sweden)

    Chen Chih-Jen

    2011-05-01

    Full Text Available Abstract Purpose This work aimed to investigate the effect of costunolide, a sesquiterpene lactone isolated from Michelia compressa, on cell cycle distribution and radiosensitivity of human hepatocellular carcinoma (HCC cells. Methods The assessment used in this study included: cell viability assay, cell cycle analysis by DNA histogram, expression of phosphorylated histone H3 (Ser 10 by flow cytometer, mitotic index by Liu's stain and morphological observation, mitotic spindle alignment by immunofluorescence of alpha-tubulin, expression of cell cycle-related proteins by Western blotting, and radiation survival by clonogenic assay. Results Our results show that costunolide reduced the viability of HA22T/VGH cells. It caused a rapid G2/M arrest at 4 hours shown by DNA histogram. The increase in phosphorylated histone H3 (Ser 10-positive cells and mitotic index indicates costunolide-treated cells are arrested at mitosis, not G2, phase. Immunofluorescence of alpha-tubulin for spindle formation further demonstrated these cells are halted at metaphase. Costunolide up-regulated the expression of phosphorylated Chk2 (Thr 68, phosphorylated Cdc25c (Ser 216, phosphorylated Cdk1 (Tyr 15 and cyclin B1 in HA22T/VGH cells. At optimal condition causing mitotic arrest, costunolide sensitized HA22T/VGH HCC cells to ionizing radiation with sensitizer enhancement ratio up to 1.9. Conclusions Costunolide could reduce the viability and arrest cell cycling at mitosis in hepatoma cells. Logical exploration of this mitosis-arresting activity for cancer therapeutics shows costunolide enhanced the killing effect of radiotherapy against human HCC cells.

  2. Prognostic value of mitotic index and Bcl2 expression in male breast cancer.

    OpenAIRE

    Lacle, M.M.; van der Pol, C.C.; Witkamp, A. J.; van der Wall, E.; van Diest, P.J.

    2013-01-01

    The incidence of male breast cancer (MBC) is rising. Current treatment regimens for MBC are extrapolated from female breast cancer (FBC), based on the assumption that FBC prognostic features and therapeutic targets can be extrapolated to MBC. However, there is yet little evidence that prognostic features that have been developed and established in FBC are applicable to MBC as well. In a recent study on FBC, a combination of mitotic index and Bcl2 expression proved to be of strong prognostic v...

  3. Caspase-Mediated Specific Cleavage of BubR1 Is a Determinant of Mitotic Progression

    OpenAIRE

    Kim, Mijin; Murphy, Katie; Liu, Fang; Parker, Sharon E.; Dowling, Melissa L.; Baff, Wesley; Kao, Gary D.

    2007-01-01

    The fidelity of chromosomal duplication is monitored by cell cycle checkpoints operational during mitosis. One such cell cycle delay is invoked by microtubule-targeting agents such as nocodazole or paclitaxel (Taxol) and is mediated by mitotic checkpoint proteins that include BubR1. Relatively little is known about the regulation of expression and stability of BubR1 (or other checkpoint proteins) and how these factors dictate the durability of the cell cycle delay. We report here that treatme...

  4. Hair cell recovery in mitotically blocked cultures of the bullfrog saccule

    OpenAIRE

    Baird, Richard A.; Burton, Miriam D.; Fashena, David S.; Naeger, Rebecca A.

    2000-01-01

    Hair cells in many nonmammalian vertebrates are regenerated by the mitotic division of supporting cell progenitors and the differentiation of the resulting progeny into new hair cells and supporting cells. Recent studies have shown that nonmitotic hair cell recovery after aminoglycoside-induced damage can also occur in the vestibular organs. Using hair cell and supporting cell immunocytochemical markers, we have used confocal and electron microscopy to examine the fate...

  5. The proteolysis of mitotic cyclins in mammalian cells persists from the end of mitosis until the onset of S phase.

    OpenAIRE

    Brandeis, M.; Hunt, T

    1996-01-01

    We have studied how the cell cycle-specific oscillations of mitotic B-type cyclins are generated in mouse fibroblasts. A reporter enzyme comprising the N-terminus of a B-type cyclin fused to bacterial chloramphenicol acetyl transferase (CAT) was degraded at the end of mitosis like endogenous cyclins. Point mutations in the destruction box of this construct completely abolished its mitotic instability. When the destructible reporter was driven by the cyclin B2 promoter, CAT activity mimicked t...

  6. Cloning of four cycling from maize indicates that higher plants have three structurally distinct groups of mitotic cyclins

    OpenAIRE

    Renaudin, J P; Colasanti, J; RIME, Hélène; Z. Yuan; Sundaresan, V.

    1994-01-01

    While a large number of cyclins have been described in animals and yeasts, very limited information is available regarding cyclins in plants. We describe here the isolation of cDNA clones encoding four putative mitotic cyclins from maize. All four cyclins were able to induce maturation of Xenopus oocytes, demonstrating that they can act as mitotic cyclins in this system. Northern analysis showed that all four cyclins were expressed only in actively dividing tissues and organs, with a stronger...

  7. Conditional Mutations in the Mitotic Chromosome Binding Function of the Bovine Papillomavirus Type 1 E2 Protein

    OpenAIRE

    Zheng, Peng-Sheng; Brokaw, Jane; Alison A McBride

    2005-01-01

    The papillomavirus E2 protein is required for viral transcriptional regulation, DNA replication and genome segregation. We have previously shown that the E2 transactivator protein and BPV1 genomes are associated with mitotic chromosomes; E2 links the genomes to cellular chromosomes to ensure efficient segregation to daughter nuclei. The transactivation domain of the E2 protein is necessary and sufficient for association of the E2 protein with mitotic chromosomes. To determine which residues o...

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

    International Nuclear Information System (INIS)

    Highlights: ► SENP1 knockout chicken DT40 cells are hypersensitive to spindle poisons. ► Spindle poison treatment of SENP1−/− cells leads to increased mitotic slippage. ► Mitotic slippage in SENP1−/− cells associates with apoptosis and endoreplication. ► SENP1 counteracts sister chromatid separation during mitotic arrest. ► Plk1-mediated cohesion down-regulation is involved in colcemid cytotoxicity. -- Abstract: SUMO conjugation is a reversible posttranslational modification that regulates protein function. SENP1 is one of the six SUMO-specific proteases present in vertebrate cells and its altered expression is observed in several carcinomas. To characterize SENP1 role in genome integrity, we generated Senp1 knockout chicken DT40 cells. SENP1−/− cells show normal proliferation, but are sensitive to spindle poisons. This hypersensitivity correlates with increased sister chromatid separation, mitotic slippage, and apoptosis. To test whether the cohesion defect had a causal relationship with the observed mitotic events, we restored the cohesive status of sister chromatids by introducing the TOP2α+/− mutation, which leads to increased catenation, or by inhibiting Plk1 and Aurora B kinases that promote cohesin release from chromosomes during prolonged mitotic arrest. Although TOP2α is SUMOylated during mitosis, the TOP2α+/− mutation had no obvious effect. By contrast, inhibition of Plk1 or Aurora B rescued the hypersensitivity of SENP1−/− cells to colcemid. In conclusion, we identify SENP1 as a novel factor required for mitotic arrest and cohesion maintenance during prolonged mitotic arrest induced by spindle poisons.

  9. Promotion of mitotic catastrophe via activation of PTEN by paclitaxel with supplement of mulberry water extract in bladder cancer cells

    OpenAIRE

    Nien-Cheng Chen; Charng-Cherng Chyau; Yi-Ju Lee; Hsien-Chun Tseng; Fen-Pi Chou

    2016-01-01

    Paclitaxel is a mitotic inhibitor used in cancer chemotherapy. Mulberry fruit is rich in phenolic compounds and flavonoids and exhibits chemopreventive activities. In this study, mulberry water extract (MWE) was used as a supplement to synergize with the effects of paclitaxel in the treatment of the TSGH 8301 human bladder cancer cell line. Treatment with paclitaxel combined with MWE (paclitaxel/MWE) enhanced the cytotoxicity of paclitaxel and induced severe G2/M arrest, mitotic catastrophe a...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-09-28

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

  11. Cdk1 orders mitotic events through coordination of a chromosome-associated phosphatase switch.

    Science.gov (United States)

    Qian, Junbin; Beullens, Monique; Huang, Jin; De Munter, Sofie; Lesage, Bart; Bollen, Mathieu

    2015-01-01

    RepoMan is a scaffold for signalling by mitotic phosphatases at the chromosomes. During (pro)metaphase, RepoMan-associated protein phosphatases PP1 and PP2A-B56 regulate the chromosome targeting of Aurora-B kinase and RepoMan, respectively. Here we show that this task division is critically dependent on the phosphorylation of RepoMan by protein kinase Cyclin-dependent kinase 1 (Cdk1), which reduces the binding of PP1 but facilitates the recruitment of PP2A-B56. The inactivation of Cdk1 in early anaphase reverses this phosphatase switch, resulting in the accumulation of PP1-RepoMan to a level that is sufficient to catalyse its own chromosome targeting in a PP2A-independent and irreversible manner. Bulk-targeted PP1-RepoMan also inactivates Aurora B and initiates nuclear-envelope reassembly through dephosphorylation-mediated recruitment of Importin β. Bypassing the Cdk1 regulation of PP1-RepoMan causes the premature dephosphorylation of its mitotic-exit substrates in prometaphase. Hence, the regulation of RepoMan-associated phosphatases by Cdk1 is essential for the timely dephosphorylation of their mitotic substrates. PMID:26674376

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

    Directory of Open Access Journals (Sweden)

    Mauricio Valerio-Santiago

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

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

    Science.gov (United States)

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

    1990-01-01

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

  14. Dovitinib induces mitotic defects and activates the G2 DNA damage checkpoint.

    Science.gov (United States)

    Man, Wing Yu; Mak, Joyce P Y; Poon, Randy Y C

    2014-01-01

    Dovitinib (TKI258; formerly CHIR-258) is an orally bioavailable inhibitor of multiple receptor tyrosine kinases. Interestingly, Dovitinib triggered a G2 /M arrest in cancer cell lines from diverse origins including HeLa, nasopharyngeal carcinoma, and hepatocellular carcinoma. Single-cell analysis revealed that Dovitinib promoted a delay in mitotic exit in a subset of cells, causing the cells to undergo mitotic slippage. Higher concentrations of Dovitinib induced a G2 arrest similar to the G2 DNA damage checkpoint. In support of this, DNA damage was triggered by Dovitinib as revealed by γ-H2AX and comet assays. The mitotic kinase CDK1 was found to be inactivated by phosphorylation in the presence of Dovitinib. Furthermore, the G2 arrest could be overcome by abrogation of the G2 DNA damage checkpoint using small molecule inhibitors of CHK1 and WEE1. Finally, Dovitinib-mediated G2 cell cycle arrest and subsequent cell death could be promoted after DNA damage repair was disrupted by inhibitors of poly(ADP-ribose) polymerases. These results are consistent with the recent finding that Dovitinib can also target topoisomerases. Collectively, these results suggest additional directions for use of Dovitinib, in particular with agents that target the DNA damage checkpoint.

  15. BubR1 is modified by sumoylation during mitotic progression.

    Science.gov (United States)

    Yang, Feikun; Hu, Liyan; Chen, Cheng; Yu, Jianxiu; O'Connell, Christopher B; Khodjakov, Alexey; Pagano, Michele; Dai, Wei

    2012-02-10

    BubR1 functions as a crucial component that monitors proper chromosome congression and mitotic timing during cell division. We investigated molecular regulation of BubR1 and found that BubR1 was modified by an unknown post-translation mechanism during the cell cycle, resulting in a significant mobility shift on denaturing gels. We termed it BubR1-M as the nature of modification was not characterized. Extended (>24 h) treatment of HeLa cells with a microtubule disrupting agent including nocodazole and taxol or release of mitotic shake-off cells into fresh medium induced BubR1-M. BubR1-M was derived from neither phosphorylation nor acetylation. Ectopic expression coupled with pulling down analyses showed that BubR1-M was derived from SUMO modification. Mutation analysis revealed that lysine 250 was a crucial site for sumoylation. Significantly, compared with the wild-type control, ectopic expression of a sumoylation-deficient mutant of BubR1 induced chromosomal missegregation and mitotic delay. Combined, our study identifies a new type of post-translational modification that is essential for BubR1 function during mitosis.

  16. PKR is activated by cellular dsRNAs during mitosis and acts as a mitotic regulator.

    Science.gov (United States)

    Kim, Yoosik; Lee, Jung Hyun; Park, Jong-Eun; Cho, Jun; Yi, Hyerim; Kim, V Narry

    2014-06-15

    dsRNA-dependent protein kinase R (PKR) is a ubiquitously expressed enzyme well known for its roles in immune response. Upon binding to viral dsRNA, PKR undergoes autophosphorylation, and the phosphorylated PKR (pPKR) regulates translation and multiple signaling pathways in infected cells. Here, we found that PKR is activated in uninfected cells, specifically during mitosis, by binding to dsRNAs formed by inverted Alu repeats (IRAlus). While PKR and IRAlu-containing RNAs are segregated in the cytosol and nucleus of interphase cells, respectively, they interact during mitosis when nuclear structure is disrupted. Once phosphorylated, PKR suppresses global translation by phosphorylating the α subunit of eukaryotic initiation factor 2 (eIF2α). In addition, pPKR acts as an upstream kinase for c-Jun N-terminal kinase and regulates the levels of multiple mitotic factors such as cyclins A and B and Polo-like kinase 1 and phosphorylation of histone H3. Disruption of PKR activation via RNAi or expression of a transdominant-negative mutant leads to misregulation of the mitotic factors, delay in mitotic progression, and defects in cytokinesis. Our study unveils a novel function of PKR and endogenous dsRNAs as signaling molecules during the mitosis of uninfected cells.

  17. PP1-mediated moesin dephosphorylation couples polar relaxation to mitotic exit.

    Science.gov (United States)

    Kunda, Patricia; Rodrigues, Nelio T L; Moeendarbary, Emadaldin; Liu, Tao; Ivetic, Aleksandar; Charras, Guillaume; Baum, Buzz

    2012-02-01

    Animal cells undergo dramatic actin-dependent changes in shape as they progress through mitosis; they round up upon mitotic entry and elongate during chromosome segregation before dividing into two [1-3]. Moesin, the sole Drosophila ERM-family protein [4], plays a critical role in this process, through the construction of a stiff, rounded metaphase cortex [5-7]. At mitotic exit, this rigid cortex must be dismantled to allow for anaphase elongation and cytokinesis through the loss of the active pool of phospho-Thr559moesin from cell poles. Here, in an RNA interference (RNAi) screen for phosphatases involved in the temporal and spatial control of moesin, we identify PP1-87B RNAi as having elevated p-moesin levels and reduced cortical compliance. In mitosis, RNAi-induced depletion of PP1-87B or depletion of a conserved noncatalytic PP1 phosphatase subunit Sds22 leads to defects in p-moesin clearance from cell poles at anaphase, a delay in anaphase elongation, together with defects in bipolar anaphase relaxation and cytokinesis. Importantly, similar cortical defects are seen at anaphase following the expression of a constitutively active, phosphomimetic version of moesin. These data reveal a new role for the PP1-87B/Sds22 phosphatase, an important regulator of the metaphase-anaphase transition, in coupling moesin-dependent cell shape changes to mitotic exit.

  18. The α isoform of topoisomerase II is required for hypercompaction of mitotic chromosomes in human cells.

    Science.gov (United States)

    Farr, Christine J; Antoniou-Kourounioti, Melissa; Mimmack, Michael L; Volkov, Arsen; Porter, Andrew C G

    2014-04-01

    As proliferating cells transit from interphase into M-phase, chromatin undergoes extensive reorganization, and topoisomerase (topo) IIα, the major isoform of this enzyme present in cycling vertebrate cells, plays a key role in this process. In this study, a human cell line conditional null mutant for topo IIα and a derivative expressing an auxin-inducible degron (AID)-tagged version of the protein have been used to distinguish real mitotic chromosome functions of topo IIα from its more general role in DNA metabolism and to investigate whether topo IIβ makes any contribution to mitotic chromosome formation. We show that topo IIβ does contribute, with endogenous levels being sufficient for the initial stages of axial shortening. However, a significant effect of topo IIα depletion, seen with or without the co-depletion of topo IIβ, is the failure of chromosomes to hypercompact when delayed in M-phase. This requires much higher levels of topo II protein and is impaired by drugs or mutations that affect enzyme activity. A prolonged delay at the G2/M border results in hyperefficient axial shortening, a process that is topo IIα-dependent. Rapid depletion of topo IIα has allowed us to show that its function during late G2 and M-phase is truly required for shaping mitotic chromosomes.

  19. Effect of Various Doses of Nicotine on Mitotic Index in Esophageal Mucosa

    Directory of Open Access Journals (Sweden)

    S. Khajeh Jahromi

    2016-07-01

    Full Text Available Introduction & Objective: Nicotine could directly act as a cancer promoter. The purpose of this study was to evaluate effects of nicotine on mitotic index in esophagus epithelium. Materials & Methods: In the present study 30 adult male mice were used. Animals were ran-domly divided into three groups. Group A or the control group received vehicle, groups B and C received nicotine intraperitoneally at doses of 0.2 and 0.4 mg/kg once daily for 14 days, re-spectively. Evaluations were made using kI-67 immunohistochemistry and Hematoxilin& Eo-sin for proliferative activity and morphometric study on esophagus mucosa, respectively. Results: Administration of nicotine in group C, showed a significant increase (P<0.05 in KI-67 index 34.15±2.50vs. 10.41±1.4 compared with the control subjects. The other parameters such as epithelial height, lamina propria, muscular mucosa and mucosa height in nicotine- treated groups were not affected. Nicotine at dose of 0.2 mg/kg did not change the mitotic in-dex in epithelium when compared with the control group. Conclusion: This study indicates nicotine at dose of 0.4 mg/kg increases mitotic activity in basal cells in esophagus epithelium. (Sci J Hamadan Univ Med Sci 2016; 23 (2:126-133

  20. Dovitinib induces mitotic defects and activates the G2 DNA damage checkpoint.

    Science.gov (United States)

    Man, Wing Yu; Mak, Joyce P Y; Poon, Randy Y C

    2014-01-01

    Dovitinib (TKI258; formerly CHIR-258) is an orally bioavailable inhibitor of multiple receptor tyrosine kinases. Interestingly, Dovitinib triggered a G2 /M arrest in cancer cell lines from diverse origins including HeLa, nasopharyngeal carcinoma, and hepatocellular carcinoma. Single-cell analysis revealed that Dovitinib promoted a delay in mitotic exit in a subset of cells, causing the cells to undergo mitotic slippage. Higher concentrations of Dovitinib induced a G2 arrest similar to the G2 DNA damage checkpoint. In support of this, DNA damage was triggered by Dovitinib as revealed by γ-H2AX and comet assays. The mitotic kinase CDK1 was found to be inactivated by phosphorylation in the presence of Dovitinib. Furthermore, the G2 arrest could be overcome by abrogation of the G2 DNA damage checkpoint using small molecule inhibitors of CHK1 and WEE1. Finally, Dovitinib-mediated G2 cell cycle arrest and subsequent cell death could be promoted after DNA damage repair was disrupted by inhibitors of poly(ADP-ribose) polymerases. These results are consistent with the recent finding that Dovitinib can also target topoisomerases. Collectively, these results suggest additional directions for use of Dovitinib, in particular with agents that target the DNA damage checkpoint. PMID:24238094

  1. Hair cell recovery in mitotically blocked cultures of the bullfrog saccule

    Science.gov (United States)

    Baird, R. A.; Burton, M. D.; Fashena, D. S.; Naeger, R. A.

    2000-01-01

    Hair cells in many nonmammalian vertebrates are regenerated by the mitotic division of supporting cell progenitors and the differentiation of the resulting progeny into new hair cells and supporting cells. Recent studies have shown that nonmitotic hair cell recovery after aminoglycoside-induced damage can also occur in the vestibular organs. Using hair cell and supporting cell immunocytochemical markers, we have used confocal and electron microscopy to examine the fate of damaged hair cells and the origin of immature hair cells after gentamicin treatment in mitotically blocked cultures of the bullfrog saccule. Extruding and fragmenting hair cells, which undergo apoptotic cell death, are replaced by scar formations. After losing their bundles, sublethally damaged hair cells remain in the sensory epithelium for prolonged periods, acquiring supporting cell-like morphology and immunoreactivity. These modes of damage appear to be mutually exclusive, implying that sublethally damaged hair cells repair their bundles. Transitional cells, coexpressing hair cell and supporting cell markers, are seen near scar formations created by the expansion of neighboring supporting cells. Most of these cells have morphology and immunoreactivity similar to that of sublethally damaged hair cells. Ultrastructural analysis also reveals that most immature hair cells had autophagic vacuoles, implying that they originated from damaged hair cells rather than supporting cells. Some transitional cells are supporting cells participating in scar formations. Supporting cells also decrease in number during hair cell recovery, supporting the conclusion that some supporting cells undergo phenotypic conversion into hair cells without an intervening mitotic event.

  2. Positive feedback promotes mitotic exit via the APC/C-Cdh1-separase-Cdc14 axis in budding yeast.

    Science.gov (United States)

    Hatano, Yuhki; Naoki, Koike; Suzuki, Asuka; Ushimaru, Takashi

    2016-10-01

    The mitotic inhibitor securin is degraded via the ubiquitin ligase anaphase-promoting complex/cyclosome (APC/C)-Cdc20 after anaphase onset. This triggers activation of the mitotic protease separase and thereby sister chromatid separation. However, only a proportion of securin molecules are degraded at metaphase-anaphase transition and the remaining molecules are still present in anaphase. The roles of securin and separase in late mitosis remain elusive. Here, we show that securin still inhibits separase to repress mitotic exit in anaphase in budding yeast. APC/C-Cdh1-mediated securin degradation at telophase further liberated separase, which promotes Cdc14 release and mitotic exit. Separase executed these events via its proteolytic action and that in the Cdc14 early release (FEAR) network. Cdc14 release further activated APC/C-Cdh1 in the manner of a positive feedback loop. Thus, the positive feedback promotes mitotic exit via the APC/C-Cdh1-separase-Cdc14 axis. This study shows the importance of the two-step degradation mode of securin and the role of separase in mitotic exit.

  3. Positive feedback promotes mitotic exit via the APC/C-Cdh1-separase-Cdc14 axis in budding yeast.

    Science.gov (United States)

    Hatano, Yuhki; Naoki, Koike; Suzuki, Asuka; Ushimaru, Takashi

    2016-10-01

    The mitotic inhibitor securin is degraded via the ubiquitin ligase anaphase-promoting complex/cyclosome (APC/C)-Cdc20 after anaphase onset. This triggers activation of the mitotic protease separase and thereby sister chromatid separation. However, only a proportion of securin molecules are degraded at metaphase-anaphase transition and the remaining molecules are still present in anaphase. The roles of securin and separase in late mitosis remain elusive. Here, we show that securin still inhibits separase to repress mitotic exit in anaphase in budding yeast. APC/C-Cdh1-mediated securin degradation at telophase further liberated separase, which promotes Cdc14 release and mitotic exit. Separase executed these events via its proteolytic action and that in the Cdc14 early release (FEAR) network. Cdc14 release further activated APC/C-Cdh1 in the manner of a positive feedback loop. Thus, the positive feedback promotes mitotic exit via the APC/C-Cdh1-separase-Cdc14 axis. This study shows the importance of the two-step degradation mode of securin and the role of separase in mitotic exit. PMID:27418100

  4. Thyroid hormone receptor interacting protein 13 (TRIP13) AAA-ATPase is a novel mitotic checkpoint-silencing protein.

    Science.gov (United States)

    Wang, Kexi; Sturt-Gillespie, Brianne; Hittle, James C; Macdonald, Dawn; Chan, Gordon K; Yen, Tim J; Liu, Song-Tao

    2014-08-22

    The mitotic checkpoint (or spindle assembly checkpoint) is a fail-safe mechanism to prevent chromosome missegregation by delaying anaphase onset in the presence of defective kinetochore-microtubule attachment. The target of the checkpoint is the E3 ubiquitin ligase anaphase-promoting complex/cyclosome. Once all chromosomes are properly attached and bioriented at the metaphase plate, the checkpoint needs to be silenced. Previously, we and others have reported that TRIP13 AAA-ATPase binds to the mitotic checkpoint-silencing protein p31(comet). Here we show that endogenous TRIP13 localizes to kinetochores. TRIP13 knockdown delays metaphase-to-anaphase transition. The delay is caused by prolonged presence of the effector for the checkpoint, the mitotic checkpoint complex, and its association and inhibition of the anaphase-promoting complex/cyclosome. These results suggest that TRIP13 is a novel mitotic checkpoint-silencing protein. The ATPase activity of TRIP13 is essential for its checkpoint function, and interference with TRIP13 abolished p31(comet)-mediated mitotic checkpoint silencing. TRIP13 overexpression is a hallmark of cancer cells showing chromosomal instability, particularly in certain breast cancers with poor prognosis. We suggest that premature mitotic checkpoint silencing triggered by TRIP13 overexpression may promote cancer development.

  5. High frequency, cell type-specific visualization of fluorescent-tagged genomic sites in interphase and mitotic cells of living Arabidopsis plants

    Directory of Open Access Journals (Sweden)

    van der Winden Johannes

    2010-01-01

    Full Text Available Abstract Background Interphase chromosome organization and dynamics can be studied in living cells using fluorescent tagging techniques that exploit bacterial operator/repressor systems and auto-fluorescent proteins. A nuclear-localized Repressor Protein-Fluorescent Protein (RP-FP fusion protein binds to operator repeats integrated as transgene arrays at defined locations in the genome. Under a fluorescence microscope, the tagged sites appear as bright fluorescent dots in living cells. This technique has been used successfully in plants, but is often hampered by low expression of genes encoding RP-FP fusion proteins, perhaps owing to one or more gene silencing mechanisms that are prevalent in plant cells. Results We used two approaches to overcome this problem. First, we tested mutations in four factors involved in different types of gene silencing and/or epigenetic modifications for their effects on nuclear fluorescence. Only mutations in DDM1, a chromatin remodelling ATPase involved in repeat-induced heterochromatin formation and DNA methylation, released silencing of the RP-FP fusion protein. This result suggested that the operator repeats can trigger silencing of the adjacent gene encoding the RP-FP fusion protein. In the second approach, we transformed the tagged lines with a second T-DNA encoding the RP-FP fusion protein but lacking operator repeats. This strategy avoided operator repeat-induced gene silencing and increased the number of interphase nuclei displaying fluorescent dots. In a further extension of the technique, we show that green fluorescent-tagged sites can be visualized on moving mitotic chromosomes stained with red fluorescent-labelled histone H2B. Conclusions The results illustrate the propensity of operator repeat arrays to form heterochromatin that can silence the neighbouring gene encoding the RP-FP fusion protein. Supplying the RP-FP fusion protein in trans from a second T-DNA largely alleviates this problem. Depending

  6. The Truth and Bias Model of Judgment

    Science.gov (United States)

    West, Tessa V.; Kenny, David A.

    2011-01-01

    We present a new model for the general study of how the truth and biases affect human judgment. In the truth and bias model, judgments about the world are pulled by 2 primary forces, the truth force and the bias force, and these 2 forces are interrelated. The truth and bias model differentiates force and value, where the force is the strength of…

  7. Measurement Bias Detection through Factor Analysis

    Science.gov (United States)

    Barendse, M. T.; Oort, F. J.; Werner, C. S.; Ligtvoet, R.; Schermelleh-Engel, K.

    2012-01-01

    Measurement bias is defined as a violation of measurement invariance, which can be investigated through multigroup factor analysis (MGFA), by testing across-group differences in intercepts (uniform bias) and factor loadings (nonuniform bias). Restricted factor analysis (RFA) can also be used to detect measurement bias. To also enable nonuniform…

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

    International Nuclear Information System (INIS)

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

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

    Directory of Open Access Journals (Sweden)

    Esser Norbert

    2011-06-01

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

  10. Auxin/AID versus conventional knockouts: distinguishing the roles of CENP-T/W in mitotic kinetochore assembly and stability

    Science.gov (United States)

    Wood, Laura; Booth, Daniel G.; Vargiu, Giulia; Ohta, Shinya; deLima Alves, Flavia; Samejima, Kumiko; Fukagawa, Tatsuo; Rappsilber, Juri; Earnshaw, William C.

    2016-01-01

    Most studies using knockout technologies to examine protein function have relied either on shutting off transcription (conventional conditional knockouts with tetracycline-regulated gene expression or gene disruption) or destroying the mature mRNA (RNAi technology). In both cases, the target protein is lost at a rate determined by its intrinsic half-life. Thus, protein levels typically fall over at least 1–3 days, and cells continue to cycle while exposed to a decreasing concentration of the protein. Here we characterise the kinetochore proteome of mitotic chromosomes isolated from a cell line in which the essential kinetochore protein CENP-T is present as an auxin-inducible degron (AID) fusion protein that is fully functional and able to support the viability of the cells. Stripping of the protein from chromosomes in early mitosis via targeted proteasomal degradation reveals the dependency of other proteins on CENP-T for their maintenance in kinetochores. We compare these results with the kinetochore proteome of conventional CENP-T/W knockouts. As the cell cycle is mostly formed from G1, S and G2 phases a gradual loss of CENP-T/W levels is more likely to reflect dependencies associated with kinetochore assembly pre-mitosis and upon entry into mitosis. Interestingly, a putative super-complex involving Rod-Zw10-zwilch (RZZ complex), Spindly, Mad1/Mad2 and CENP-E requires the function of CENP-T/W during kinetochore assembly for its stable association with the outer kinetochore, but once assembled remains associated with chromosomes after stripping of CENP-T during mitosis. This study highlights the different roles core kinetochore components may play in the assembly of kinetochores (upon entry into mitosis) versus the maintenance of specific components (during mitosis). PMID:26791246

  11. Bias in Dynamic Monte Carlo Alpha Calculations

    Energy Technology Data Exchange (ETDEWEB)

    Sweezy, Jeremy Ed [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Nolen, Steven Douglas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Adams, Terry R. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Trahan, Travis John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-02-06

    A 1/N bias in the estimate of the neutron time-constant (commonly denoted as α) has been seen in dynamic neutronic calculations performed with MCATK. In this paper we show that the bias is most likely caused by taking the logarithm of a stochastic quantity. We also investigate the known bias due to the particle population control method used in MCATK. We conclude that this bias due to the particle population control method is negligible compared to other sources of bias.

  12. Minimum Bias Trigger in ATLAS

    International Nuclear Information System (INIS)

    Since the restart of the LHC in November 2009, ATLAS has collected inelastic pp collisions to perform first measurements on charged particle densities. These measurements will help to constrain various models describing phenomenologically soft parton interactions. Understanding the trigger efficiencies for different event types are therefore crucial to minimize any possible bias in the event selection. ATLAS uses two main minimum bias triggers, featuring complementary detector components and trigger levels. While a hardware based first trigger level situated in the forward regions with 2.2 < |η| < 3.8 has been proven to select pp-collisions very efficiently, the Inner Detector based minimum bias trigger uses a random seed on filled bunches and central tracking detectors for the event selection. Both triggers were essential for the analysis of kinematic spectra of charged particles. Their performance and trigger efficiency measurements as well as studies on possible bias sources will be presented. We also highlight the advantage of these triggers for particle correlation analyses. (author)

  13. Perception bias in route choice

    NARCIS (Netherlands)

    Vreeswijk, J.D.; Thomas, T.; Berkum, van E.C.; Arem, van B.

    2014-01-01

    Travel time is probably one of the most studied attributes in route choice. Recently, perception of travel time received more attention as several studies have shown its importance in explaining route choice behavior. In particular, travel time estimates by travelers appear to be biased against non-

  14. Microturbulence measurements during divertor biasing

    International Nuclear Information System (INIS)

    The application of a bias voltage to a neutralization plate of the upper divertor with respect to the vacuum chamber in the Tokamak de Varennes (TdeV) influences the plasma well inside the separatrix. In particular, the unbiased Ohmic poloidal rotation edge velocity measured by visible spectroscopy is found to be in the electron diamagnetic drift direction (2-3 km/s) and increases by a factor of two for Vbias = 100 V. This coincides with a major reduction of the microturbulence signal at low frequencies (50 kHz -1 -1), as determined from coherent laser scattering measurements. One possible explanation is that the turbulence signal is simply Doppler shifted to frequencies outside the accessible range. This scenario is, however, difficult to reconcile with some observations. Another explanation invokes a reduction of the turbulence level. The variation of the turbulence signal as a function of the applied bias voltage can indeed be reproduced with a theoretical model based on radial and poloidal decorrelation mechanisms, the latter corresponding to poloidal velocity shear stabilization. This model also explains the observed steepening of the k-spectrum decay during biasing. Biasing also modifies the electron density profile inside the separatrix. These changes of nabla ne cannot explain the behaviour of microturbulence behaviour, when explained in terms of stabilization, would agree with the plasma maintaining a steeper electron density gradient. (author). 17 refs, 9 figs

  15. Attentional bias in math anxiety

    Science.gov (United States)

    Rubinsten, Orly; Eidlin, Hili; Wohl, Hadas; Akibli, Orly

    2015-01-01

    Cognitive theory from the field of general anxiety suggests that the tendency to display attentional bias toward negative information results in anxiety. Accordingly, the current study aims to investigate whether attentional bias is involved in math anxiety (MA) as well (i.e., a persistent negative reaction to math). Twenty seven participants (14 with high levels of MA and 13 with low levels of MA) were presented with a novel computerized numerical version of the well established dot probe task. One of six types of prime stimuli, either math related or typically neutral, was presented on one side of a computer screen. The prime was preceded by a probe (either one or two asterisks) that appeared in either the prime or the opposite location. Participants had to discriminate probe identity (one or two asterisks). Math anxious individuals reacted faster when the probe was at the location of the numerical related stimuli. This suggests the existence of attentional bias in MA. That is, for math anxious individuals, the cognitive system selectively favored the processing of emotionally negative information (i.e., math related words). These findings suggest that attentional bias is linked to unduly intense MA symptoms. PMID:26528208

  16. Attentional Bias in Math Anxiety

    Directory of Open Access Journals (Sweden)

    Orly eRubinsten

    2015-10-01

    Full Text Available Cognitive theory from the field of general anxiety suggests that the tendency to display attentional bias toward negative information results in anxiety. Accordingly, the current study aims to investigate whether attentional bias is involved in math anxiety as well (i.e., a persistent negative reaction to math. Twenty seven participants (14 with high levels of math anxiety and 13 with low levels of math anxiety were presented with a novel computerized numerical version of the well established dot probe task. One of 6 types of prime stimuli, either math related or typically neutral, were presented on one side of a computer screen. The prime was preceded by a probe (either one or two asterisks that appeared in either the prime or the opposite location. Participants had to discriminate probe identity (one or two asterisks. Math anxious individuals reacted faster when the probe was at the location of the numerical related stimuli. This suggests the existence of attentional bias in math anxiety. That is, for math anxious individuals, the cognitive system selectively favored the processing of emotionally negative information (i.e., math related words. These findings suggest that attentional bias is linked to unduly intense math anxiety symptoms.

  17. Stereotype Formation : Biased by Association

    NARCIS (Netherlands)

    Le Pelley, Mike E.; Reimers, Stian J.; Calvini, Guglielmo; Spears, Russell; Beesley, Tom; Murphy, Robin A.

    2010-01-01

    We propose that biases in attitude and stereotype formation might arise as a result of learned differences ill the extent its which social groups have previously been predictive elf behavioral or physical properties Experiments 1 and 2 demonstrate that differences in the experienced predictiveness o

  18. Attentional bias in math anxiety.

    Science.gov (United States)

    Rubinsten, Orly; Eidlin, Hili; Wohl, Hadas; Akibli, Orly

    2015-01-01

    Cognitive theory from the field of general anxiety suggests that the tendency to display attentional bias toward negative information results in anxiety. Accordingly, the current study aims to investigate whether attentional bias is involved in math anxiety (MA) as well (i.e., a persistent negative reaction to math). Twenty seven participants (14 with high levels of MA and 13 with low levels of MA) were presented with a novel computerized numerical version of the well established dot probe task. One of six types of prime stimuli, either math related or typically neutral, was presented on one side of a computer screen. The prime was preceded by a probe (either one or two asterisks) that appeared in either the prime or the opposite location. Participants had to discriminate probe identity (one or two asterisks). Math anxious individuals reacted faster when the probe was at the location of the numerical related stimuli. This suggests the existence of attentional bias in MA. That is, for math anxious individuals, the cognitive system selectively favored the processing of emotionally negative information (i.e., math related words). These findings suggest that attentional bias is linked to unduly intense MA symptoms.

  19. Condensin-mediated chromosome organization and gene regulation

    Directory of Open Access Journals (Sweden)

    Alyssa Christine Lau

    2015-01-01

    Full Text Available In many organisms sexual fate is determined by a chromosome-based method which entails a difference in sex chromosome-linked gene dosage. Consequently, a gene regulatory mechanism called dosage compensation equalizes X-linked gene expression between the sexes. Dosage compensation initiates as cells transition from pluripotency to differentiation. In C. elegans, dosage compensation is achieved by the dosage compensation complex (DCC binding to both X chromosomes in hermaphrodites to downregulate gene expression by two fold. The DCC contains a subcomplex (condensin IDC similar to the evolutionarily conserved condensin complexes which play a fundamental role in chromosome dynamics during mitosis. Therefore, mechanisms related to mitotic chromosome condensation are hypothesized to mediate dosage compensation. Consistent with this hypothesis, monomethylation of histone H4 lysine 20 (H4K20 is increased, whereas acetylation of histone H4 lysine 16 (H4K16 is decreased, both on mitotic chromosomes and on interphase dosage compensated X chromosomes in worms. These observations suggest that interphase dosage compensated X chromosomes maintain some characteristics associated with condensed mitotic chromosome. This chromosome state is stably propagated from one cell generation to the next. In this review we will speculate on how the biochemical activities of condensin can achieve both mitotic chromosome compaction and gene repression.

  20. Lysine-specific demethylase-1 (LSD1) is compartmentalized at nuclear chromocenters in early post-mitotic cells of the olfactory sensory neuronal lineage.

    Science.gov (United States)

    Kilinc, Seda; Savarino, Alyssa; Coleman, Julie H; Schwob, James E; Lane, Robert P

    2016-07-01

    Mammalian olfaction depends on the development of specialized olfactory sensory neurons (OSNs) that each express one odorant receptor (OR) protein from a large family of OR genes encoded in the genome. The lysine-specific demethylase-1 (LSD1) protein removes activating H3K4 or silencing H3K9 methylation marks at gene promoters and is required for proper OR regulation. We show that LSD1 protein exhibits variable organization within nuclei of developing OSNs, and tends to consolidate into a single dominant compartment at the edges of chromocenters within nuclei of early post-mitotic cells of the mouse olfactory epithelium (MOE). Using an immortalized cell line derived from developing olfactory placode, we show that consolidation of LSD1 appears to be cell-cycle regulated, with a peak occurrence in early G1. LSD1 co-compartmentalizes with CoREST, a protein known to collaborate with LSD1 to carry out a variety of chromatin-modifying functions. We show that LSD1 compartments co-localize with 1-3 OR loci at the exclusion of most OR genes, and commonly associate with Lhx2, a transcription factor involved in OR regulation. Together, our data suggests that LSD1 is sequestered into a distinct nuclear space that might restrict a histone-modifying function to a narrow developmental time window and/or range of OR gene targets. PMID:26947098

  1. A model for codon position bias in RNA editing

    CERN Document Server

    Liu, T; Liu, Tsunglin; Bundschuh, Ralf

    2005-01-01

    RNA editing can be crucial for the expression of genetic information via inserting, deleting, or substituting a few nucleotides at specific positions in an RNA sequence. Within coding regions in an RNA sequence, editing usually occurs with a certain bias in choosing the positions of the editing sites. In the mitochondrial genes of {\\it Physarum polycephalum}, many more editing events have been observed at the third codon position than at the first and second, while in some plant mitochondria the second codon position dominates. Here we propose an evolutionary model that explains this bias as the basis of selection at the protein level. The model predicts a distribution of the three positions rather close to the experimental observation in {\\it Physarum}. This suggests that the codon position bias in {\\it Physarum} is mainly a consequence of selection at the protein level.

  2. Bias Adjusted Precipitation Threat Scores

    Directory of Open Access Journals (Sweden)

    F. Mesinger

    2008-04-01

    Full Text Available Among the wide variety of performance measures available for the assessment of skill of deterministic precipitation forecasts, the equitable threat score (ETS might well be the one used most frequently. It is typically used in conjunction with the bias score. However, apart from its mathematical definition the meaning of the ETS is not clear. It has been pointed out (Mason, 1989; Hamill, 1999 that forecasts with a larger bias tend to have a higher ETS. Even so, the present author has not seen this having been accounted for in any of numerous papers that in recent years have used the ETS along with bias "as a measure of forecast accuracy".

    A method to adjust the threat score (TS or the ETS so as to arrive at their values that correspond to unit bias in order to show the model's or forecaster's accuracy in extit{placing} precipitation has been proposed earlier by the present author (Mesinger and Brill, the so-called dH/dF method. A serious deficiency however has since been noted with the dH/dF method in that the hypothetical function that it arrives at to interpolate or extrapolate the observed value of hits to unit bias can have values of hits greater than forecast when the forecast area tends to zero. Another method is proposed here based on the assumption that the increase in hits per unit increase in false alarms is proportional to the yet unhit area. This new method removes the deficiency of the dH/dF method. Examples of its performance for 12 months of forecasts by three NCEP operational models are given.

  3. A study of the low level radiation effect on the mitotic index of the basal cells in the buccal pouch of hamsters

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Byung Cheol; You, Dong Soo [Dept. of Oral and Maxillofacial Radiology, College of Dentistry, Seoul National University, Seoul (Korea, Republic of)

    1993-08-15

    The purpose of this study was to investigate the defects of the low level irradiation on the mitotic index of the basal cells in the buccal pouch of hamsters (golden hamster: APG strain). After colchicine was administrated to the hamsters through the intraperitoneal, the low level radiation (5461 mR) was exposed in the buccal pouch of hamsters. The mitotic index of the basal cells was estimated 2 hours after irradiation. The results were as follows: 1. The mean mitotic index of the control group was 4.32. 2. The mean mitotic index of the irradiated group was 2.46. 3. T-test of data in the irradiated group showed significant difference from the mitotic endex in the control group. These results suggested the lowered mitotic index of the irradiated group resulted from the low level irradiation.

  4. Computerized video time lapse study of cell cycle delay and arrest, mitotic catastrophe, apoptosis and clonogenic survival in irradiated 14-3-3sigma and CDKN1A (p21) knockout cell lines.

    Science.gov (United States)

    Chu, Kenneth; Teele, Noella; Dewey, Michael W; Albright, Norman; Dewey, William C

    2004-09-01

    Computerized video time lapse (CVTL) microscopy was used to observe cellular events induced by ionizing radiation (10-12 Gy) in nonclonogenic cells of the wild-type HCT116 colorectal carcinoma cell line and its three isogenic derivative lines in which p21 (CDKN1A), 14-3-3sigma or both checkpoint genes (double-knockout) had been knocked out. Cells that fused after mitosis or failed to complete mitosis were classified together as cells that underwent mitotic catastrophe. Seventeen percent of the wild-type cells and 34-47% of the knockout cells underwent mitotic catastrophe to enter generation 1 with a 4N content of DNA, i.e., the same DNA content as irradiated cells arrested in G(2) at the end of generation 0. Radiation caused a transient division delay in generation 0 before the cells divided or underwent mitotic catastrophe. Compared with the division delay for wild-type cells that express CDKN1A and 14-3-3sigma, knocking out CDKN1A reduced the delay the most for cells irradiated in G(1) (from approximately 15 h to approximately 3- 5 h), while knocking out 14-3-3sigma reduced the delay the most for cells irradiated in late S and G(2) (from approximately 18 h to approximately 3-4 h). However, 27% of wild-type cells and 17% of 14-3-3sigma(-/-) cells were arrested at 96 h in generation 0 compared with less than 1% for CDKN1A(-/-) and double-knockout cells. Thus expression of CDKN1A is necessary for the prolonged delay or arrest in generation 0. Furthermore, CDKN1A plays a crucial role in generation 1, greatly inhibiting progression into subsequent generations of both diploid cells and polyploid cells produced by mitotic catastrophe. Thus, in CDKN1A-deficient cell lines, a series of mitotic catastrophe events occurred to produce highly polyploid progeny during generations 3 and 4. Most importantly, the polyploid progeny produced by mitotic catastrophe events did not die sooner than the progeny of dividing cells. Death was identified as loss of cell movement, i

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

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    Hsieh Yi-Jen

    2012-09-01

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

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

    Science.gov (United States)

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

    2016-01-01

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

  7. Study on the radioprotective effect of cystamine and mexamine during two subsequent mitotic cycles

    Energy Technology Data Exchange (ETDEWEB)

    Sidorov, V.P. (Vsesoyuznyj Nauchno-ssledovatel' skij Inst. I Khimizatsii Lesnogo Khozyajstva, Pushkino (USSR))

    The radioprotective agents were found to be effective in relation to chromosomal aberrations occuring during both the first and the second mitotic cycles. It was shown that the radioprotective effect of cystamine and mexamine is completely removed by the effect of the inhibitor of DNA synthesis, 5-aminouracil. It is suggested that the radioprotective effect of the protective agents is realized through the formation of complexes between the radioprotective agent and the genetically active loci of chromosome DNA rather than through the reduction of radiation-induced DNA lesions.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-10-15

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

  9. Bursa of Fabricius--mitotic index in the follicles of immunized and non-immunized chicks (Gallus domesticus).

    Science.gov (United States)

    Betti, F; Borella, M I

    1979-01-01

    The mitotic index in the cortical compartment of the follicles of the bursa of Fabricius from chicks immunized with sheep red blood cells (SRBC) is always higher when compaired with non-immunized ones. This mitotic index reachs its maximum 6 days after the SRBC injection, coincident with the highest serum antibody titer. The mitotic activity in the cortex of the follicles of the bursa of Fabricius is always higher than that of the medulla during the postembryonic development of chickens (PROCHAZKA, RODAK, KREJCI 1967). Otherwise it is almost established that the cortex is a zone of continuous lymphocyte proliferation, not occuring the same with the medulla. In addition these bursal histological structures are considered as 2 distinct compartments (GROSSI et al. 1974). The purpose of this paper is to study the response in the mitotic index of the cortical and medullary compartments of the follicles of the bursa of immunized and non-immunized chicks. To correlate possible changes in the mitotic index with circulating antibody levels, the serum antibody titer from the same birds was also recorded.

  10. Cell death, chromosome damage and mitotic delay in normal human, ataxia telangiectasia and retinoblastoma fibroblasts after x-irradiation.

    Science.gov (United States)

    Zampetti-Bosseler, F; Scott, D

    1981-05-01

    We recently showed (Scott and Zampetti-Bosseler 1980) that X-ray sensitive mouse lymphoma cells sustain more chromosome damage, mitotic delay and spindle defects than X-ray resistant cells. We proposed that (a) chromosome aberrations contribute much more to lethality than spindle defects, and (b) that DNA lesions are less effectively repaired in the sensitive cells and give rise to more G2 mitotic delay and chromosome aberrations. Our present results on human fibroblasts with reported differential sensitivity to ionizing radiation (i.e. normal donors and patients with ataxia telangiectasia and retinoblastoma) support the first hypothesis since we observed a positive correlation between chromosome aberration frequencies and cell killing and no induced spindle defects. Our second hypothesis is however not substantiated since X-ray sensitive fibroblasts from the ataxia patient suffered less mitotic delay than cells from normal donors. A common lesion for mitotic delay and chromosome aberrations can still be assumed by adopting the hypothesis of Painter and Young (1981) that the defect in ataxia cells is not in repair but in a failure of DNA damage to initiate mitotic delay. In contrast to other reports, we found the retinoblastoma cells to be of normal radiation sensitivity (cell killing and aberration).

  11. Glycogen synthase kinase 3 β activity is required for hBora/Aurora A-mediated mitotic entry.

    Science.gov (United States)

    Lee, Yu-Cheng; Liao, Po-Chi; Liou, Yih-Cherng; Hsiao, Michael; Huang, Chi-Ying; Lu, Pei-Jung

    2013-03-15

    The synthesis and degradation of hBora is important for the regulation of mitotic entry and exist. In G 2 phase, hBora can complex with Aurora A to activate Plk1 and control mitotic entry. However, whether the post-translational modification of hBora is relevant to the mitotic entry still unclear. Here, we used the LC-MS/MS phosphopeptide mapping assay to identify 13 in vivo hBora phosphorylation sites and characterized that GSK3β can interact with hBora and phosphorylate hBora at Ser274 and Ser278. Pharmacological inhibitors of GSK3β reduced the retarded migrating band of hBora in cells and diminished the phosphorylation of hBora by in vitro kinase assay. Moreover, as well as in GSK3β activity-inhibited cells, specific knockdown of GSK3β by shRNA and S274A/S278 hBora mutant-expressing cells also exhibited the reduced Plk1 activation and a delay in mitotic entry. It suggests that GSK3β activity is required for hBora-mediated mitotic entry through Ser274 and Ser278 phosphorylation.

  12. Reduction of UV-induced mitotic delay by caffeine in BUdR-substituted plasmodia of Physarum polycephalum.

    Science.gov (United States)

    Jayasree, P R; Nair, V R

    1993-02-01

    Chromosomal DNA of the synchronously mitotic plasmodia of P. polycephalum was substituted with 5-bromo-2'-deoxyuridine, by growing the plasmodia during S phase, on a medium containing this nucleoside analog. A strong synergism was observed between bromodeoxyuridine and UV-irradiation, in late G2-irradiated plasmodia in that, the mitotic delay obtained in them was much more than a simple sum of the delays induced by these two agents individually. It was also observed that the mitotic delay in this system is reduced significantly by different concentrations of caffeine applied immediately after irradiation and there was a stage specificity in this effect. The reduction in mitotic delay was maximum (80%) in those plasmodia irradiated 20-30 min before control metaphase, when mitogenic factors also reach their maximum activity in this system. It is proposed that the mitotic delay reducing effect of caffeine is due to its ability to promote the activity of the mitogenic factors, largely independent of the system which is responsible for monitoring the state of the chromosomal DNA.

  13. Prolonged mitotic arrest induces a caspase-dependent DNA damage response at telomeres that determines cell survival.

    Science.gov (United States)

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

    2016-05-27

    A delay in the completion of metaphase induces a stress response that inhibits further cell proliferation or induces apoptosis. This response is thought to protect against genomic instability and is important for the effects of anti-mitotic cancer drugs. Here, we show that mitotic arrest induces a caspase-dependent DNA damage response (DDR) at telomeres in non-apoptotic cells. This pathway is under the control of Mcl-1 and other Bcl-2 family proteins and requires caspase-9, caspase-3/7 and the endonuclease CAD/DFF40. The gradual caspase-dependent loss of the shelterin complex protein TRF2 from telomeres promotes a DDR that involves DNA-dependent protein kinase (DNA-PK). Suppression of mitotic telomere damage by enhanced expression of TRF2, or the inhibition of either caspase-3/7 or DNA-PK during mitotic arrest, promotes subsequent cell survival. Thus, we demonstrate that mitotic stress is characterised by the sub-apoptotic activation of a classical caspase pathway, which promotes telomere deprotection, activates DNA damage signalling, and determines cell fate in response to a prolonged delay in mitosis.

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

    Science.gov (United States)

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

    2016-06-01

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

  15. Prolonged mitotic arrest induces a caspase-dependent DNA damage response at telomeres that determines cell survival.

    Science.gov (United States)

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

    2016-01-01

    A delay in the completion of metaphase induces a stress response that inhibits further cell proliferation or induces apoptosis. This response is thought to protect against genomic instability and is important for the effects of anti-mitotic cancer drugs. Here, we show that mitotic arrest induces a caspase-dependent DNA damage response (DDR) at telomeres in non-apoptotic cells. This pathway is under the control of Mcl-1 and other Bcl-2 family proteins and requires caspase-9, caspase-3/7 and the endonuclease CAD/DFF40. The gradual caspase-dependent loss of the shelterin complex protein TRF2 from telomeres promotes a DDR that involves DNA-dependent protein kinase (DNA-PK). Suppression of mitotic telomere damage by enhanced expression of TRF2, or the inhibition of either caspase-3/7 or DNA-PK during mitotic arrest, promotes subsequent cell survival. Thus, we demonstrate that mitotic stress is characterised by the sub-apoptotic activation of a classical caspase pathway, which promotes telomere deprotection, activates DNA damage signalling, and determines cell fate in response to a prolonged delay in mitosis. PMID:27230693

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

    Directory of Open Access Journals (Sweden)

    Zhong Rong Zhang

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

  17. Belief bias and relational reasoning.

    Science.gov (United States)

    Roberts, Maxwell J; Sykes, Elizabeth D A

    2003-01-01

    When people evaluate categorical syllogisms, they tend to reject unbelievable conclusions and accept believable ones irrespective of their validity. Typically, this effect is particularly marked for invalid conclusions that are possible, but do not necessarily follow, given the premises. However, smaller believability effects can also be detected for other types of conclusion. Three experiments are reported here, in which an attempt was made to determine whether belief bias effects can manifest themselves on the relational inference task. Subjects evaluated the validity of conclusions such as William the Conqueror was king after the Pyramids were built (temporal task) or Manchester is north of Bournemouth (spatial task) with respect to their premises. All of the major findings for equivalent categorical syllogism tasks were replicated. However, the overall size of the main effect of believability appears to be related to task presentation, a phenomenon not previously identified for categorical syllogisms and which current theories of belief bias have difficulty explaining.

  18. A quantum exchange bias model

    International Nuclear Information System (INIS)

    The origin of the exchange bias phenomenon is investigated on the basis of a quantum mechanical model. In particular, the mechanisms that determine the magnetic structure in the vicinity of an antiferromagnetic-ferromagnetic interface are reexamined. This way we establish how the breaking of translational invariance modifies quantum spin fluctuations. It is found that non-uniform fluctuations induce uncompensated spins in the antiferromagnet, which in turn give rise to a dipole field that couples to the magnetization of the ferromagnet. This coupling yields an exchange bias field that is of the order of magnitude of the one observed experimentally. A net surface magnetization should also be experimentally observable in a clean antiferromagnetic surface

  19. Opinion Dynamics with Confirmation Bias

    CERN Document Server

    Allahverdyan, A E

    2014-01-01

    Background: Confirmation bias is the tendency to acquire or evaluate new information in a way that is consistent with one's preexisting beliefs. It is omnipresent in psychology, economics, and even scientific practices. Prior theoretical research of this phenomenon has mainly focused on its economic implications possibly missing its potential connections with broader notions of cognitive science. Methodology/Principal Findings: We formulate a (non-Bayesian) model for revising subjective probabilistic opinion of a confirmationally-biased agent in the light of a persuasive opinion. The revision rule ensures that the agent does not react to persuasion that is either far from his current opinion or coincides with it. We demonstrate that the model accounts for the basic phenomenology of the social judgment theory, and allows to study various phenomena such as cognitive dissonance and boomerang effect. The model also displays the order of presentation effect|when consecutively exposed to two opinions, the preferenc...

  20. Probability biases as Bayesian inference

    Directory of Open Access Journals (Sweden)

    Andre; C. R. Martins

    2006-11-01

    Full Text Available In this article, I will show how several observed biases in human probabilistic reasoning can be partially explained as good heuristics for making inferences in an environment where probabilities have uncertainties associated to them. Previous results show that the weight functions and the observed violations of coalescing and stochastic dominance can be understood from a Bayesian point of view. We will review those results and see that Bayesian methods should also be used as part of the explanation behind other known biases. That means that, although the observed errors are still errors under the be understood as adaptations to the solution of real life problems. Heuristics that allow fast evaluations and mimic a Bayesian inference would be an evolutionary advantage, since they would give us an efficient way of making decisions. %XX In that sense, it should be no surprise that humans reason with % probability as it has been observed.