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1

Extragnathic odontogenic sinonasal myxoma with mitotic features  

PubMed Central

We present the first-ever documented evidence of mitotic figures in a case of sinonasal myxoma diagnosed in a 37 year-old gentleman. A 37 year-old gentleman was referred to the Otolaryngology clinic with left nasal discharge for six months. Preoperative images demonstrated obstruction of the left nasal airway with complete opacification of the left maxillary sinus, obscuration of the osteomeatal complex, as well as expansion and thinning of the medial wall of the maxillary antrum. The patient underwent diagnostic Funtional Endoscopic Sinus Surgery (FESS), therapeutic left Caldwell-Luc antrostomy, and revision FESS following recurrence. The patient was symptom-free at routine follow-up post-op. There has been much debate as to whether the absence of mitotic features in a specimen is absolutely necessary in order to confirm the diagnosis. We postulate that the presence of mitoses is an unusual diagnostic feature in extensive sinonasal myxoma.

Onyekwelu, O; DeZoysa, O; Watts, S

2012-01-01

2

Classification of mitotic figures with convolutional neural networks and seeded blob features  

PubMed Central

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.

Malon, Christopher D.; Cosatto, Eric

2013-01-01

3

Automated High-Throughput Quantification of Mitotic Spindle Positioning from DIC Movies of Caenorhabditis Embryos.  

PubMed

The mitotic spindle is a microtubule-based structure that elongates to accurately segregate chromosomes during anaphase. Its position within the cell also dictates the future cell cleavage plan, thereby determining daughter cell orientation within a tissue or cell fate adoption for polarized cells. Therefore, the mitotic spindle ensures at the same time proper cell division and developmental precision. Consequently, spindle dynamics is the matter of intensive research. Among the different cellular models that have been explored, the one-cell stage C. elegans embryo has been an essential and powerful system to dissect the molecular and biophysical basis of spindle elongation and positioning. Indeed, in this large and transparent cell, spindle poles (or centrosomes) can be easily detected from simple DIC microscopy by human eyes. To perform quantitative and high-throughput analysis of spindle motion, we developed a computer program ACT for Automated-Centrosome-Tracking from DIC movies of C. elegans embryos. We therefore offer an alternative to the image acquisition and processing of transgenic lines expressing fluorescent spindle markers. Consequently, experiments on large sets of cells can be performed with a simple setup using inexpensive microscopes. Moreover, analysis of any mutant or wild-type backgrounds is accessible because laborious rounds of crosses with transgenic lines become unnecessary. Last, our program allows spindle detection in other nematode species, offering the same quality of DIC images but for which techniques of transgenesis are not accessible. Thus, our program also opens the way towards a quantitative evolutionary approach of spindle dynamics. Overall, our computer program is a unique macro for the image- and movie-processing platform ImageJ. It is user-friendly and freely available under an open-source licence. ACT allows batch-wise analysis of large sets of mitosis events. Within 2 minutes, a single movie is processed and the accuracy of the automated tracking matches the precision of the human eye. PMID:24763198

Cluet, David; Stébé, Pierre-Nicolas; Riche, Soizic; Spichty, Martin; Delattre, Marie

2014-01-01

4

Automated High-Throughput Quantification of Mitotic Spindle Positioning from DIC Movies of Caenorhabditis Embryos  

PubMed Central

The mitotic spindle is a microtubule-based structure that elongates to accurately segregate chromosomes during anaphase. Its position within the cell also dictates the future cell cleavage plan, thereby determining daughter cell orientation within a tissue or cell fate adoption for polarized cells. Therefore, the mitotic spindle ensures at the same time proper cell division and developmental precision. Consequently, spindle dynamics is the matter of intensive research. Among the different cellular models that have been explored, the one-cell stage C. elegans embryo has been an essential and powerful system to dissect the molecular and biophysical basis of spindle elongation and positioning. Indeed, in this large and transparent cell, spindle poles (or centrosomes) can be easily detected from simple DIC microscopy by human eyes. To perform quantitative and high-throughput analysis of spindle motion, we developed a computer program ACT for Automated-Centrosome-Tracking from DIC movies of C. elegans embryos. We therefore offer an alternative to the image acquisition and processing of transgenic lines expressing fluorescent spindle markers. Consequently, experiments on large sets of cells can be performed with a simple setup using inexpensive microscopes. Moreover, analysis of any mutant or wild-type backgrounds is accessible because laborious rounds of crosses with transgenic lines become unnecessary. Last, our program allows spindle detection in other nematode species, offering the same quality of DIC images but for which techniques of transgenesis are not accessible. Thus, our program also opens the way towards a quantitative evolutionary approach of spindle dynamics. Overall, our computer program is a unique macro for the image- and movie-processing platform ImageJ. It is user-friendly and freely available under an open-source licence. ACT allows batch-wise analysis of large sets of mitosis events. Within 2 minutes, a single movie is processed and the accuracy of the automated tracking matches the precision of the human eye.

Cluet, David; Spichty, Martin; Delattre, Marie

2014-01-01

5

High throughput screening of natural products for anti-mitotic effects in MDA-MB-231 human breast carcinoma cells.  

PubMed

Some of the most effective anti-mitotic microtubule-binding agents, such as paclitaxel (Taxus brevifolia) were originally discovered through robust National Cancer Institute botanical screenings. In this study, a high-through put microarray format was utilized to screen 897 aqueous extracts of commonly used natural products (0.00015-0.5?mg/mL) relative to paclitaxel for anti-mitotic effects (independent of toxicity) on proliferation of MDA-MB-231 cells. The data obtained showed that less than 1.34 % of the extracts tested showed inhibitory growth (IG50 ) properties <0.0183?mg/mL. The most potent anti-mitotics (independent of toxicity) were Mandrake root (Podophyllum peltatum), Truja twigs (Thuja occidentalis), Colorado desert mistletoe (Phoradendron flavescens), Tou Gu Cao [symbol: see text] Speranskia herb (Speranskia tuberculata), Bentonite clay, Bunge root (Pulsatilla chinensis), Brucea fruit (Brucea javanica), Madder root (Rubia tinctorum), Gallnut of Chinese Sumac (Melaphis chinensis), Elecampane root (Inula Helenium), Yuan Zhi [symbol: see text] root (Polygala tenuifolia), Pagoda Tree fruit (Melia Toosendan), Stone root (Collinsonia Canadensis), and others such as American Witchhazel, Arjun, and Bladderwrack. The strongest tumoricidal herbs identified from amongst the subset evaluated for anti-mitotic properties were wild yam (Dioscorea villosa), beth root (Trillium Pendulum), and alkanet root (Lithospermum canescens). Additional data was obtained on a lesser-recognized herb: (S. tuberculata), which showed growth inhibition on BT-474 (human ductal breast carcinoma) and Ishikawa (human endometrial adenocarcinoma) cells with ability to block replicative DNA synthesis, leading to G2 arrest in MDA-MB-231 cells. In conclusion, these findings present relative potency of anti-mitotic natural plants that are effective against human breast carcinoma MDA-MB-231 cell division. PMID:24105850

Mazzio, E; Badisa, R; Mack, N; Deiab, S; Soliman, K F A

2014-06-01

6

CBFS: High Performance Feature Selection Algorithm Based on Feature Clearness  

PubMed Central

Background The goal of feature selection is to select useful features and simultaneously exclude garbage features from a given dataset for classification purposes. This is expected to bring reduction of processing time and improvement of classification accuracy. Methodology In this study, we devised a new feature selection algorithm (CBFS) based on clearness of features. Feature clearness expresses separability among classes in a feature. Highly clear features contribute towards obtaining high classification accuracy. CScore is a measure to score clearness of each feature and is based on clustered samples to centroid of classes in a feature. We also suggest combining CBFS and other algorithms to improve classification accuracy. Conclusions/Significance From the experiment we confirm that CBFS is more excellent than up-to-date feature selection algorithms including FeaLect. CBFS can be applied to microarray gene selection, text categorization, and image classification.

Seo, Minseok; Oh, Sejong

2012-01-01

7

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

PubMed

The count of mitotic cells is a critical factor in most cancer grading systems. Extracting the mitotic cell from the histopathological image is a very challenging task. In this paper, we propose an efficient technique for detecting and segmenting the mitotic cells in the high-resolution multispectral image. The proposed technique consists of three main modules: discriminative image generation, mitotic cell candidate detection and segmentation, and mitotic cell candidate classification. In the first module, a discriminative image is obtained by linear discriminant analysis using ten different spectral band images. A set of mitotic cell candidate regions is then detected and segmented by the Bayesian modeling and local-region threshold method. In the third module, a 226 dimension feature is extracted from the mitotic cell candidates and their surrounding regions. An imbalanced classification framework is then applied to perform the classification for the mitotic cell candidates in order to detect the real mitotic cells. The proposed technique has been evaluated on a publicly available dataset of 35 × 10 multispectral images, in which 224 mitotic cells are manually labeled by experts. The proposed technique is able to provide superior performance compared to the existing technique, 81.5% sensitivity rate and 33.9% precision rate in terms of detection performance, and 89.3% sensitivity rate and 87.5% precision rate in terms of segmentation performance. PMID:24608059

Lu, Cheng; Mandal, Mrinal

2014-03-01

8

The Drosophila salivary gland chromocenter contains highly polytenized subdomains of mitotic heterochromatin.  

PubMed

Peri-centromeric regions of Drosophila melanogaster chromosomes appear heterochromatic in mitotic cells and become greatly underrepresented in giant polytene chromosomes, where they aggregate into a central mass called the chromocenter. We used P elements inserted at sites dispersed throughout much of the mitotic heterochromatin to analyze the fate of 31 individual sites during polytenization. Analysis of DNA sequences flanking many of these elements revealed that middle repetitive or unique sequence DNAs frequently are interspersed with satellite DNAs in mitotic heterochromatin. All nine Y chromosome sites tested were underrepresented > 20-fold on Southern blots of polytene DNA and were rarely or never detected by in situ hybridization to salivary gland chromosomes. In contrast, nine tested insertions in autosomal centromeric heterochromatin were represented fully in salivary gland DNA, despite the fact that at least six were located proximal to known blocks of satellite DNA. The inserted sequences formed diverse, site-specific morphologies in the chromocenter of salivary gland chromosomes, suggesting that domains dispersed at multiple sites in the centromeric heterochromatin of mitotic chromosomes contribute to polytene beta-heterochromatin. We suggest that regions containing heterochromatic genes are organized into dispersed chromatin configurations that are important for their function in vivo. PMID:7713423

Zhang, P; Spradling, A C

1995-02-01

9

Extremely High-Dimensional Feature Selection via Feature Generating Samplings.  

PubMed

To select informative features on extremely high-dimensional problems, in this paper, a sampling scheme is proposed to enhance the efficiency of recently developed feature generating machines (FGMs). Note that in FGMs O(mlogr) time complexity should be taken to order the features by their scores; the entire computational cost of feature ordering will become unbearable when m is very large, for example, m > 10(11) , where m is the feature dimensionality and r is the size of the selected feature subset. To solve this problem, in this paper, we propose a feature generating sampling method, which can reduce this computational complexity to O(Gslog(G)+G(G+log(G))) while preserving the most informative features in a feature buffer, where Gs is the maximum number of nonzero features for each instance and G is the buffer size. Moreover, we show that our proposed sampling scheme can be deemed as the birth-death process based on random processes theory, which guarantees to include most of the informative features for feature selections. Empirical studies on real-world datasets show the effectiveness of the proposed sampling method. PMID:23864272

Li, Shutao; Wei, Dan

2014-06-01

10

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

PubMed

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. PMID:24204306

Yin, Yi; Petes, Thomas D

2013-10-01

11

Mitotic repression of transcription in vitro  

PubMed Central

A normal consequence of mitosis in eukaryotes is the repression of transcription. Using Xenopus egg extracts shifted to a mitotic state by the addition of purified cyclin, we have for the first time been able to reproduce a mitotic repression of transcription in vitro. Active RNA polymerase III transcription is observed in interphase extracts, but strongly repressed in extracts converted to mitosis. With the topoisomerase II inhibitor VM-26, we demonstrate that this mitotic repression of RNA polymerase III transcription does not require normal chromatin condensation. Similarly; in vitro mitotic repression of transcription does not require the presence of nucleosome structure or involve a general repressive chromatin-binding protein, as inhibition of chromatin formation with saturating amounts of non-specific DNA has no effect on repression. Instead, the mitotic repression of transcription appears to be due to phosphorylation of a component of the transcription machinery by a mitotic protein kinase, either cdc2 kinase and/or a kinase activated by it. Mitotic repression of RNA polymerase III transcription is observed both in complete mitotic cytosol and when a kinase-enriched mitotic fraction is added to a highly simplified 5S RNA transcription reaction. We present evidence that, upon depletion of cdc2 kinase, a secondary protein kinase activity remains and can mediate this in vitro mitotic repression of transcription.

1993-01-01

12

CBFS: High Performance Feature Selection Algorithm Based on Feature Clearness  

Microsoft Academic Search

BackgroundThe goal of feature selection is to select useful features and simultaneously exclude garbage features from a given dataset for classification purposes. This is expected to bring reduction of processing time and improvement of classification accuracy.MethodologyIn this study, we devised a new feature selection algorithm (CBFS) based on clearness of features. Feature clearness expresses separability among classes in a feature.

Minseok Seo; Sejong Oh

2012-01-01

13

Mitotic toxicity, sister chromatid exchange, and rec assay of pesticides  

Microsoft Academic Search

Genotoxicity of 10 pesticides (chlornitrofen, chlomethoxyfen, molinate, thiobencarb, simazine, simetryn, diazinon, iprofenfos, piperofos and oxadiazone) was studied by mitotic toxicity, sister chromatid exchange, and rec assay. The pesticides are detected frequently at high levels in the Yodo River water in Osaka, Japan, which is used for drinking water by thirteen million people. Mitotic toxicity was evaluated by mitotic index (MI)

Koichi Kuroda; Yukihiko Yamaguchi; Ginji Endo

1992-01-01

14

Data Assimilation of Highly Nonlinear Features  

NASA Astrophysics Data System (ADS)

Promising approaches to data assimilation (DA) utilizing Lagrangian flow information are investigated in systems exhibiting highly nonlinear features such as tight vortices and fronts. Optimal methods in DA only exist for strictly linear problems. Though atmospheric dynamics are certainly not linear, dynamics at the synoptic-scale are thought to at least be approximately linear over short enough time scales. Hence, much of the on-going research in the field has been aimed at implementing these optimal linear methods operationally. However, consumers of numerical weather prediction (NWP) products are often most interested in the accurate prediction of weather that is associated with strong ``features'', e.g., tropical cyclones leading to potential coastal evacuations and tight fronts and squall lines that may lead to severe weather warnings. These features usually cannot be considered linear for NWP/DA purposes because the typical errors in their prediction can grow very quickly and become the same order of magnitude as the signal itself. Linear DA methods are expected to fail in these instances. No realizable optimal methods for nonlinear state estimation exist. We examine the ability of several different ensemble-based DA methods to handle systems with strong embedded features. A barotropic model is used to model the flow generated by a simple, though chaotic, point vortex system. Highlighting limitations to the more traditional methods, we present results which suggest Lagrangian methods are more adept at managing features.

Lawson, W.; Hansen, J. A.; Emanuel, K. A.

2001-12-01

15

P2P-R protein overexpression restricts mitotic progression at prometaphase and promotes mitotic apoptosis.  

PubMed

Mitotic cells show a tenfold increase in immunoreactive P2P-R protein. During mitosis, the distribution of P2P-R protein also changes from a primary nucleolar localization in interphase cells to the periphery of chromosome in mitotic cells. These findings suggest that P2P-R might serve a functional role in mitosis. To test this possibility, human Saos2 cells were stably transfected with P2P-R DNA constructs and the biological effects of P2P-R overexpression were evaluated. Overexpression of near full-length P2P-R was found to have paradoxical effects on the relationship between proliferation and mitosis in the nine Saos2 cell clones that were studied. A significant repression in the population doubling rates was observed in all nine clones even though a significant increase in the frequency of easily detached cells with a mitotic morphology was apparent. Flow cytometric analysis confirmed that greater than two thirds of the cells with a mitotic morphology had a 4n DNA content. Confocal microscopy further established that 85% of the mitotic cell population had prometaphase characteristics suggesting that P2P-R overexpression restricts mitotic progression at prometaphase. Many cells with a mitotic morphology also showed signs of apoptosis with prominent cell surface blebs. Confocal microscopy confirmed that 25-40% of such mitotic cells were apoptotic with chromosomal abnormalities and cell surface blebbing. In association with mitotic apoptosis, P2P-R protein appears to dissociate from the periphery of chromosomes and localize in the cytoplasm and in cell surface blebs. The presence of P2P-R in cell surface blebs was confirmed by analysis of highly enriched populations of apoptotic cell surface blebs wherein Western blotting documented the presence of 250 kDa P2P-R. These results therefore suggest that P2P-R overexpression promotes both prometaphase arrest in mitosis and mitotic apoptosis. PMID:12384997

Gao, Sizhi; Scott, Robert E

2002-11-01

16

High mitotic activity of Polo-like kinase 1 is required for chromosome segregation and genomic integrity in human epithelial cells.  

PubMed

Protein kinases play key roles in regulating human cell biology, but manifold substrates and functions make it difficult to understand mechanism. We tested whether we could dissect functions of a pleiotropic mitotic kinase, Polo-like kinase 1 (Plk1), via distinct thresholds of kinase activity. We accomplished this by titrating Plk1 activity in RPE1 human epithelial cells using chemical genetics and verifying results in additional lines. We found that distinct activity thresholds are required for known functions of Plk1 including (from low to high activity) bipolar spindle formation, timely mitotic entry, and formation of a cytokinesis cleavage furrow. Subtle losses in Plk1 activity impaired chromosome congression and produced severe anaphase dysfunction characterized by poor separation of chromosome masses. These two phenotypes were separable, suggesting that they stem from distinct phosphorylation events. Impaired chromosome segregation in anaphase was the most sensitive to modest loss in Plk1 activity. Mechanistically, it was associated with unpaired sister chromatids with stretched kinetochores, suggestive of merotelic attachments. The C-terminal Polo box domain of Plk1 was required for its anaphase function, although it was dispensable for forming a bipolar spindle. The ultimate effect of partial inhibition of Plk1 was the formation of micronuclei, an increase in tetraploid progeny, and senescence. These results demonstrate that different thresholds of Plk1 activity can elicit distinct phenotypes, illustrating a general method for separating pleiotropic functions of a protein kinase even when these are executed close in time. PMID:23105120

Lera, Robert F; Burkard, Mark E

2012-12-14

17

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

PubMed Central

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.

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

2011-01-01

18

Sources and structures of mitotic crossovers that arise when BLM helicase is absent in Drosophila.  

PubMed

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

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

2014-01-01

19

Highly discriminative statistical features for email classification  

Microsoft Academic Search

This paper reports on email classification and filtering, more specifically on spam versus ham and phishing versus spam classification,\\u000a based on content features. We test the validity of several novel statistical feature extraction methods. The methods rely\\u000a on dimensionality reduction in order to retain the most informative and discriminative features. We successfully test our\\u000a methods under two schemas. The first

Juan Carlos Gomez; Erik Boiy; Marie-Francine Moens

20

Mitotic bookmarking by transcription factors  

PubMed Central

Mitosis is accompanied by dramatic changes in chromatin organization and nuclear architecture. Transcription halts globally and most sequence-specific transcription factors and co-factors are ejected from mitotic chromatin. How then does the cell maintain its transcriptional identity throughout the cell division cycle? It has become clear that not all traces of active transcription and gene repression are erased within mitotic chromatin. Many histone modifications are stable or only partially diminished throughout mitosis. In addition, some sequence-specific DNA binding factors have emerged that remain bound to select sites within mitotic chromatin, raising the possibility that they function to transmit regulatory information through the transcriptionally silent mitotic phase, a concept that has been termed “mitotic bookmarking.” Here we review recent approaches to studying potential bookmarking factors with regards to their mitotic partitioning, and summarize emerging ideas concerning the in vivo functions of mitotically bound nuclear factors.

2013-01-01

21

ControlNet features high speed  

SciTech Connect

ControlNet is a high-speed, high-capacity network providing a connection among controllers and I/O subsystems. It was designed for applications in which data integrity, determinism, high speeds, and high data capacities are required. ControlNet addresses applications needing tighter control over processes as well as demanding remote I/O or interlocked PLC applications, both discrete- and process-related. Some examples include high-speed conveyors, transfer lines, cut-to-length lines, high-speed assembly, bottling, and packaging. Process examples, or those typically requiring heavy remote analog I/O, include water/wastewater, test stands, chemical, beverage, food, marine control, and utility balance-of-plant.

McEldowney, D.

1996-11-01

22

Using High-Level Semantic Features in Video Retrieval  

Microsoft Academic Search

Extraction and utilization of high-level semantic features are critical for more effective video retrieval. However, the performance of video retrieval hasn't benefited much despite of the advances in high-level feature extraction. To make good use of high-level semantic features in video retrieval, we present a method called pointwise mutual informa- tion weighted scheme(PMIWS). The method makes a good judgment of

Wujie Zheng; Jianmin Li; Zhangzhang Si; Fuzong Lin; Bo Zhang

2006-01-01

23

Organization of the mitotic chromosome  

PubMed Central

Mitotic chromosomes are among the most recognizable structures in the cell, yet for over a century their internal organization remains largely unsolved. We applied chromosome conformation capture methods, 5C and Hi-C, across the cell cycle and revealed two alternative three-dimensional folding states of the human genome. We show that the highly compartmentalized and cell-type-specific organization described previously for non-synchronous cells is restricted to interphase. In metaphase, we identify a homogenous folding state, which is locus-independent, common to all chromosomes, and consistent among cell types, suggesting a general principle of metaphase chromosome organization. Using polymer simulations, we find that metaphase Hi-C data is inconsistent with classic hierarchical models, and is instead best described by a linearly-organized longitudinally compressed array of consecutive chromatin loops.

Naumova, Natalia; Imakaev, Maxim; Fudenberg, Geoffrey; Zhan, Ye; Lajoie, Bryan R.; Mirny, Leonid A.; Dekker, Job

2014-01-01

24

A new genetic method for isolating functionally interacting genes: high plo1(+)-dependent mutants and their suppressors define genes in mitotic and septation pathways in fission yeast.  

PubMed Central

We describe a general genetic method to identify genes encoding proteins that functionally interact with and/or are good candidates for downstream targets of a particular gene product. The screen identifies mutants whose growth depends on high levels of expression of that gene. We apply this to the plo1(+) gene that encodes a fission yeast homologue of the polo-like kinases. plo1(+) regulates both spindle formation and septation. We have isolated 17 high plo1(+)-dependent (pld) mutants that show defects in mitosis or septation. Three mutants show a mitotic arrest phenotype. Among the 14 pld mutants with septation defects, 12 mapped to known loci: cdc7, cdc15, cdc11 spg1, and sid2. One of the pld mutants, cdc7-PD1, was selected for suppressor analysis. As multicopy suppressors, we isolated four known genes involved in septation in fission yeast: spg1(+), sce3(+), cdc8(+), and rho1(+), and two previously uncharacterized genes, mpd1(+) and mpd2(+). mpd1(+) exhibits high homology to phosphatidylinositol 4-phosphate 5-kinase, while mpd2(+) resembles Saccharomyces cerevisiae SMY2; both proteins are involved in the regulation of actin-mediated processes. As chromosomal suppressors of cdc7-PD1, we isolated mutations of cdc16 that resulted in multiseptation without nuclear division. cdc16(+), dma1(+), byr3(+), byr4(+) and a truncated form of the cdc7 gene were isolated by complementation of one of these cdc16 mutations. These results demonstrate that screening for high dose-dependent mutants and their suppressors is an effective approach to identify functionally interacting genes.

Cullen, C F; May, K M; Hagan, I M; Glover, D M; Ohkura, H

2000-01-01

25

Mitotic Spindle Form and Function  

PubMed Central

The Saccharomyces cerevisiae mitotic spindle in budding yeast is exemplified by its simplicity and elegance. Microtubules are nucleated from a crystalline array of proteins organized in the nuclear envelope, known as the spindle pole body in yeast (analogous to the centrosome in larger eukaryotes). The spindle has two classes of nuclear microtubules: kinetochore microtubules and interpolar microtubules. One kinetochore microtubule attaches to a single centromere on each chromosome, while approximately four interpolar microtubules emanate from each pole and interdigitate with interpolar microtubules from the opposite spindle to provide stability to the bipolar spindle. On the cytoplasmic face, two to three microtubules extend from the spindle pole toward the cell cortex. Processes requiring microtubule function are limited to spindles in mitosis and to spindle orientation and nuclear positioning in the cytoplasm. Microtubule function is regulated in large part via products of the 6 kinesin gene family and the 1 cytoplasmic dynein gene. A single bipolar kinesin (Cin8, class Kin-5), together with a depolymerase (Kip3, class Kin-8) or minus-end-directed kinesin (Kar3, class Kin-14), can support spindle function and cell viability. The remarkable feature of yeast cells is that they can survive with microtubules and genes for just two motor proteins, thus providing an unparalleled system to dissect microtubule and motor function within the spindle machine.

Winey, Mark; Bloom, Kerry

2012-01-01

26

Unsupervised Feature Learning for High-Resolution Satellite Image Classification  

SciTech Connect

The rich data provided by high-resolution satellite imagery allow us to directly model geospatial neighborhoods by understanding their spatial and structural patterns. In this paper we explore an unsupervised feature learning approach to model geospatial neighborhoods for classification purposes. While pixel and object based classification approaches are widely used for satellite image analysis, often these approaches exploit the high-fidelity image data in a limited way. In this paper we extract low-level features to characterize the local neighborhood patterns. We exploit the unlabeled feature measurements in a novel way to learn a set of basis functions to derive new features. The derived sparse feature representation obtained by encoding the measured features in terms of the learned basis function set yields superior classification performance. We applied our technique on two challenging image datasets: ORNL dataset representing one-meter spatial resolution satellite imagery representing five land-use categories and, UCMERCED dataset consisting of 21 different categories representing sub-meter resolution overhead imagery. Our results are highly promising and, in the case of UCMERCED dataset we outperform the best results obtained for this dataset. We show that our feature extraction and learning methods are highly effective in developing a detection system that can be used to automatically scan large-scale high-resolution satellite imagery for detecting large-facility.

Cheriyadat, Anil M [ORNL

2013-01-01

27

Micromechanical studies of mitotic chromosomes  

Microsoft Academic Search

Mitotic chromosomes respond elastically to forces in the nanonewton range, a property important to transduction of stresses\\u000a used as mechanical regulatory signals during cell division. In addition to being important biologically, chromosome elasticity\\u000a can be used as a tool for investigating the folding of chromatin. This paper reviews experiments studying stretching and bending\\u000a stiffness of mitotic chromosomes, plus experiments where

John F. Marko

2008-01-01

28

High Dimensional Classification Using Features Annealed Independence Rules  

PubMed Central

Classification using high-dimensional features arises frequently in many contemporary statistical studies such as tumor classification using microarray or other high-throughput data. The impact of dimensionality on classifications is largely poorly understood. In a seminal paper, Bickel and Levina (2004) show that the Fisher discriminant performs poorly due to diverging spectra and they propose to use the independence rule to overcome the problem. We first demonstrate that even for the independence classification rule, classification using all the features can be as bad as the random guessing due to noise accumulation in estimating population centroids in high-dimensional feature space. In fact, we demonstrate further that almost all linear discriminants can perform as bad as the random guessing. Thus, it is paramountly important to select a subset of important features for high-dimensional classification, resulting in Features Annealed Independence Rules (FAIR). The conditions under which all the important features can be selected by the two-sample t-statistic are established. The choice of the optimal number of features, or equivalently, the threshold value of the test statistics are proposed based on an upper bound of the classification error. Simulation studies and real data analysis support our theoretical results and demonstrate convincingly the advantage of our new classification procedure.

Fan, Jianqing

2008-01-01

29

OVARIAN LOW-GRADE AND HIGH-GRADE SEROUS CARCINOMA: Pathogenesis, Clinicopathologic and Molecular Biologic Features, and Diagnostic Problems  

PubMed Central

Ovarian serous carcinomas have been graded using various systems. Recently, a 2-tier system in which tumors are subdivided into low-grade and high-grade has been proposed. This approach is simplistic, reproducible, and based on biologic evidence indicating that both tumors develop via different pathways. Low-grade serous carcinomas exhibit low-grade nuclei with infrequent mitotic figures. They evolve from adenofibromas or borderline tumors, have frequent mutations of the KRAS, BRAF, or ERBB2 genes, and lack TP53 mutations (Type I pathway). The progression to invasive carcinoma is a slow step-wise process. Low-grade tumors are indolent and have better outcome than high-grade tumors. In contrast, high-grade serous carcinomas have high-grade nuclei and numerous mitotic figures. Identification of a precursor lesion in the ovary has been elusive and therefore the origin of ovarian carcinoma has been described as de novo. More recently, studies have suggested that a proportion appear to originate from intraepithelial carcinoma in the fallopian tube. The development of these tumors is rapid (Type II pathway). The vast majority are characterized by TP53 mutations and lack mutations of KRAS, BRAF, or ERBB2. Although both types of serous carcinomas evolve along different pathways, rare high-grade serous carcinomas seem to arise through the Type I pathway. Immunohistochemical stains for p53, p16, and Ki-67 for distinction of low- from high-grade tumors are of limited value but can be helpful in selected instances. This review provides an update on the pathogenesis and clinicopathologic features of these two types of serous carcinomas and addresses some of the diagnostic problems that are encountered in routine practice.

Vang, Russell; Shih, Ie-Ming; Kurman, Robert J.

2009-01-01

30

Ovarian low-grade and high-grade serous carcinoma: pathogenesis, clinicopathologic and molecular biologic features, and diagnostic problems.  

PubMed

Ovarian serous carcinomas have been graded using various systems. Recently, a 2-tier system in which tumors are subdivided into low grade and high grade has been proposed. This approach is simplistic, reproducible, and based on biologic evidence indicating that both tumors develop via different pathways. Low-grade serous carcinomas exhibit low-grade nuclei with infrequent mitotic figures. They evolve from adenofibromas or borderline tumors, have frequent mutations of the KRAS, BRAF, or ERBB2 genes, and lack TP53 mutations (Type I pathway). The progression to invasive carcinoma is a slow step-wise process. Low-grade tumors are indolent and have better outcome than high-grade tumors. In contrast, high-grade serous carcinomas have high-grade nuclei and numerous mitotic figures. Identification of a precursor lesion in the ovary has been elusive and therefore the origin of ovarian carcinoma has been described as de novo. More recently, studies have suggested that a proportion seem to originate from intraepithelial carcinoma in the fallopian tube. The development of these tumors is rapid (Type II pathway). Most are characterized by TP53 mutations and lack mutations of KRAS, BRAF, or ERBB2. Although both types of serous carcinomas evolve along different pathways, rare high-grade serous carcinomas seem to arise through the Type I pathway. Immunohistochemical stains for p53, p16, and Ki-67 for distinction of low-grade from high-grade tumors are of limited value but can be helpful in selected instances. This review provides an update on the pathogenesis and clinicopathologic features of these 2 types of serous carcinomas and addresses some of the diagnostic problems that are encountered in routine practice. PMID:19700937

Vang, Russell; Shih, Ie-Ming; Kurman, Robert J

2009-09-01

31

Chromosome loops arising from intrachromosomal tethering of telomeres occur at high frequency in G1 (non-cycling) mitotic cells: Implications for telomere capture  

PubMed Central

Background To investigate potential mechanisms for telomere capture the spatial arrangement of telomeres and chromosomes was examined in G1 (non-cycling) mitotic cells with diploid or triploid genomes. This was examined firstly by directly labelling the respective short arm (p) and long arm subtelomeres (q) with different fluorophores and probing cell preparations using a number of subtelomere probe pairs, those for chromosomes 1, 3, 4, 5, 6, 7, 9, 10, 12, 17, 18, and 20. In addition some interstitial probes (CEN15, PML and SNRPN on chromosome 15) and whole chromosome paint probes (e.g. WCP12) were jointly hybridised to investigate the co-localization of interphase chromosome domains and tethered subtelomeres. Cells were prepared by omitting exposure to colcemid and hypotonic treatments. Results In these cells a specific interphase chromosome topology was detected. It was shown that the p and q telomeres of the each chromosome associate frequently (80% pairing) in an intrachromosomal manner, i.e. looped chromosomes with homologues usually widely spaced within the nucleus. This p-q tethering of the telomeres from the one chromosome was observed with large (chromosomes 3, 4, 5), medium sized (6, 7, 9, 10, 12), or small chromosomes (17, 18, 20). When triploid nuclei were probed there were three tetherings of p-q subtelomere signals representing the three widely separated looped chromosome homologues. The separate subtelomere pairings were shown to coincide with separate chromosome domains as defined by the WCP and interstitial probes. The 20% of apparently unpaired subtelomeric signals in diploid nuclei were partially documented to be pairings with the telomeres of other chromosomes. Conclusions A topology for telomeres was detected where looped chromosome homologues were present at G1 interphase. These homologues were spatially arranged with respect to one-another independently of other chromosomes, i.e. there was no chromosome order on different sides of the cell nuclei and no segregation into haploid sets was detected. The normal function of this high frequency of intrachromosomal loops is unknown but a potential role is likely in the genesis of telomere captures whether of the intrachromosomal type or between non-homologues. This intrachromosomal tethering of telomeres cannot be related to telomeric or subtelomeric sequences since these are shared in varying degree with other chromosomes. In our view, these intrachromosomal telomeric tetherings with the resulting looped chromosomes arranged in a regular topology must be important to normal cell function since non-cycling cells in G1 are far from quiescent, are in fact metabolically active, and these cells represent the majority status since only a small proportion of cells are normally dividing.

Daniel, Art; St Heaps, Luke

2004-01-01

32

High-speed digital signal normalization for feature identification  

NASA Technical Reports Server (NTRS)

A design approach for high speed normalization of digital signals was developed. A reciprocal look up table technique is employed, where a digital value is mapped to its reciprocal via a high speed memory. This reciprocal is then multiplied with an input signal to obtain the normalized result. Normalization improves considerably the accuracy of certain feature identification algorithms. By using the concept of pipelining the multispectral sensor data processing rate is limited only by the speed of the multiplier. The breadboard system was found to operate at an execution rate of five million normalizations per second. This design features high precision, a reduced hardware complexity, high flexibility, and expandability which are very important considerations for spaceborne applications. It also accomplishes a high speed normalization rate essential for real time data processing.

Ortiz, J. A.; Meredith, B. D.

1983-01-01

33

The structural mechanisms that underpin mitotic kinase activation.  

PubMed

In eukaryotic cells, the peak of protein phosphorylation occurs during mitosis, switching the activities of a significant proportion of proteins and orchestrating a wholesale reorganization of cell shape and internal architecture. Most mitotic protein phosphorylation events are catalysed by a small subset of serine/threonine protein kinases. These include members of the Cdk (cyclin-dependent kinase), Plk (Polo-like kinase), Aurora, Nek (NimA-related kinase) and Bub families, as well as Haspin, Greatwall and Mps1/TTK. There has been steady progress in resolving the structural mechanisms that regulate the catalytic activities of these mitotic kinases. From structural and biochemical perspectives, kinase activation appears not as a binary process (from inactive to active), but as a series of states that exhibit varying degrees of activity. In its lowest activity state, a mitotic kinase may exhibit diverse autoinhibited or inactive conformations. Kinase activation proceeds via phosphorylation and/or association with a binding partner. These remodel the structure into an active conformation that is common to almost all protein kinases. However, all mitotic kinases of known structure have divergent features, many of which are key to understanding their specific regulatory mechanisms. Finally, mitotic kinases are an important class of drug target, and their structural characterization has facilitated the rational design of chemical inhibitors. PMID:23863175

Dodson, Charlotte A; Haq, Tamanna; Yeoh, Sharon; Fry, Andrew M; Bayliss, Richard

2013-08-01

34

High-Resolution Urban Image Classification Using Extended Features.  

National Technical Information Service (NTIS)

High-resolution image classification poses several challenges because the typical object size is much larger than the pixel resolution. Any given pixel (spectral features at that location) by itself is not a good indicator of the object it belongs to with...

R. R. Vatsavai

2013-01-01

35

The effects of high presentation levels on consonant feature transmission.  

PubMed

The effect of high speech presentation levels on consonant recognition and feature transmission was assessed in eight participants with normal hearing. Consonant recognition in noise (0 dB signal-to-noise ratio) was measured at five overall speech levels ranging from 65 to 100 dB SPL. Consistent with the work of others, overall percent correct performance decreased as the presentation level of speech increased [e.g., G. A. Studebaker, R. L. Sherbecoe, D. M. McDaniel, and C. A. Gwaltney, J. Acoust. Soc. Am. 105(4), 2431-2444 (1999)]. Confusion matrices were analyzed in terms of relative percent information transmitted at each speech presentation level, as a function of feature. Six feature sets (voicing, place, nasality, duration, frication, and sonorance) were analyzed. Results showed the feature duration (long consonant duration fricatives) to be most affected by increases in level, while the voicing feature was relatively unaffected by increases in level. In addition, alveolar consonants were substantially affected by level, while palatal consonants were not. While the underlying mechanisms responsible for decreases in performance with level increases are unclear, an analysis of common error patterns at high levels suggests that saturation of the neural response and/or a loss of neural synchrony may play a role. PMID:16240830

Hornsby, Benjamin W Y; Trine, Timothy D; Ohde, Ralph N

2005-09-01

36

Exploiting Conversational Features to Detect High-Quality Blog Comments  

Microsoft Academic Search

\\u000a In this work, we present a method for classifying the quality of blog comments using Linear-Chain Conditional Random Fields\\u000a (CRFs). This approach is found to yield high accuracy on binary classification of high-quality comments, with conversational\\u000a features contributing strongly to the accuracy. We also present a new corpus of blog data in conversational form, complete\\u000a with user-generated quality moderation labels

Nicholas FitzGerald; Giuseppe Carenini; Gabriel Murray; Shafiq Joty

37

Type 2 NF1 deletions are highly unusual by virtue of the absence of nonallelic homologous recombination hotspots and an apparent preference for female mitotic recombination.  

PubMed

Approximately 5% of patients with neurofibromatosis type 1 (NF1) exhibit gross deletions that encompass the NF1 gene and its flanking regions. The breakpoints of the common 1.4-Mb (type 1) deletions are located within low-copy repeats (NF1-REPs) and cluster within a 3.4-kb hotspot of nonallelic homologous recombination (NAHR). Here, we present the first comprehensive breakpoint analysis of type 2 deletions, which are a second type of recurring NF1 gene deletion. Type 2 deletions span 1.2 Mb and are characterized by breakpoints located within the SUZ12 gene and its pseudogene, which closely flank the NF1-REPs. Breakpoint analysis of 13 independent type 2 deletions did not reveal any obvious hotspots of NAHR. However, an overrepresentation of polypyrimidine/polypurine tracts and triplex-forming sequences was noted in the breakpoint regions that could have facilitated NAHR. Intriguingly, all 13 type 2 deletions identified so far are characterized by somatic mosaicism, which indicates a positional preference for mitotic NAHR within the NF1 gene region. Indeed, whereas interchromosomal meiotic NAHR occurs between the NF1-REPs giving rise to type 1 deletions, NAHR during mitosis appears to occur intrachromosomally between the SUZ12 gene and its pseudogene, thereby generating type 2 deletions. Such a clear distinction between the preferred sites of mitotic versus meiotic NAHR is unprecedented in any other genomic disorder induced by the local genomic architecture. Additionally, 12 of the 13 mosaic type 2 deletions were found in females. The marked female preponderance among mosaic type 2 deletions contrasts with the equal sex distribution noted for type 1 and/or atypical NF1 deletions. Although an influence of chromatin structure was strongly suspected, no sex-specific differences in the methylation pattern exhibited by the SUZ12 gene were apparent that could explain the higher rate of mitotic recombination in females. PMID:17999360

Steinmann, Katharina; Cooper, David N; Kluwe, Lan; Chuzhanova, Nadia A; Senger, Cornelia; Serra, Eduard; Lazaro, Conxi; Gilaberte, Montserrat; Wimmer, Katharina; Mautner, Viktor-Felix; Kehrer-Sawatzki, Hildegard

2007-12-01

38

An unmet actin requirement explains the mitotic inhibition of clathrin-mediated endocytosis  

PubMed Central

Clathrin-mediated endocytosis (CME) is the major internalisation route for many different receptor types in mammalian cells. CME is shut down during early mitosis, but the mechanism of this inhibition is unclear. In this study, we show that the mitotic shutdown is due to an unmet requirement for actin in CME. In mitotic cells, membrane tension is increased and this invokes a requirement for the actin cytoskeleton to assist the CME machinery to overcome the increased load. However, the actin cytoskeleton is engaged in the formation of a rigid cortex in mitotic cells and is therefore unavailable for deployment. We demonstrate that CME can be ‘restarted’ in mitotic cells despite high membrane tension, by allowing actin to engage in endocytosis. Mitotic phosphorylation of endocytic proteins is maintained in mitotic cells with restored CME, indicating that direct phosphorylation of the CME machinery does not account for shutdown. DOI: http://dx.doi.org/10.7554/eLife.00829.001

Kaur, Satdip; Fielding, Andrew B; Gassner, Gisela; Carter, Nicholas J; Royle, Stephen J

2014-01-01

39

Additive channel-constrained metallization of high-resolution features  

Microsoft Academic Search

The patterned, selective electroless deposition of submicron metal features has been achieved on Si by using a channel-constrained technique. Chemically-amplified negative tone photoresists, exposed with UV or e-beam sources, were developed to create patterned channels for constrained, additive, metal growth on an underlying ligating self-assembled monolayer film. The process is attractive for the production of plasma etch-resistant high resolution metal

Mu-San Chen; Susan L Brandow; Walter J Dressick

2000-01-01

40

EGF Induced Centrosome Separation Promotes Mitotic Progression and Cell Survival  

PubMed Central

Summary Timely and accurate assembly of the mitotic spindle is critical for the faithful segregation of chromosomes and centrosome separation is a key step in this process. The timing of centrosome separation varies dramatically between cell types; however, the mechanisms responsible for these differences and its significance are unclear. Here, we show that activation of epidermal growth factor receptor (EGFR) signaling determines the timing of centrosome separation. Premature separation of centrosomes decreases the requirement for the major mitotic kinesin Eg5 for spindle assembly, accelerates mitosis and decreases the rate of chromosome missegregation. Importantly, EGF stimulation impacts upon centrosome separation and mitotic progression to different degrees in different cell lines. Cells with high EGFR levels fail to arrest in mitosis upon Eg5 inhibition. This has important implications for cancer therapy since cells with high centrosomal response to EGF are more susceptible to combinatorial inhibition of EGFR and Eg5.

Mardin, Balca R.; Isokane, Mayumi; Cosenza, Marco R.; Kramer, Alwin; Ellenberg, Jan; Fry, Andrew M.; Schiebel, Elmar

2014-01-01

41

Plk2 regulates mitotic spindle orientation and mammary gland development.  

PubMed

Disruptions in polarity and mitotic spindle orientation contribute to the progression and evolution of tumorigenesis. However, little is known about the molecular mechanisms regulating these processes in vivo. Here, we demonstrate that Polo-like kinase 2 (Plk2) regulates mitotic spindle orientation in the mammary gland and that this might account for its suggested role as a tumor suppressor. Plk2 is highly expressed in the mammary gland and is required for proper mammary gland development. Loss of Plk2 leads to increased mammary epithelial cell proliferation and ductal hyperbranching. Additionally, a novel role for Plk2 in regulating the orientation of the mitotic spindle and maintaining proper cell polarity in the ductal epithelium was discovered. In support of a tumor suppressor function for Plk2, loss of Plk2 increased the formation of lesions in multiparous glands. Collectively, these results demonstrate a novel role for Plk2 in regulating mammary gland development. PMID:24598160

Villegas, Elizabeth; Kabotyanski, Elena B; Shore, Amy N; Creighton, Chad J; Westbrook, Thomas F; Rosen, Jeffrey M

2014-04-01

42

A mitotic spindle-independent cleavage furrow positioning pathway  

PubMed Central

The mitotic spindle determines the cleavage furrow site during metazoan cell division1,2, but whether other mechanisms exist remains unknown. Here we identify a spindle-independent mechanism for cleavage furrow positioning in Drosophila neuroblasts. We show that early and late furrow proteins (Pavarotti, Anillin, and Myosin) are localized to the neuroblast basal cortex at anaphase onset by a Pins cortical polarity pathway, and can induce a basally-displaced furrow even in the complete absence of a mitotic spindle. Rotation or displacement of the spindle results in two furrows: an early polarity-induced basal furrow and a later spindle-induced furrow. This spindle-independent cleavage furrow mechanism may be relevant to other highly polarized mitotic cells, such as mammalian neural progenitors.

Cabernard, Clemens; Prehoda, Kenneth E.

2014-01-01

43

[Metabolism features of bacteria resistant to high concentrations of chromate].  

PubMed

Twenty strains of bacteria resistant to high concentrations of chromate were isolated from different ecological niches. They were able to reduce chromate to compounds of trivalent chromium--nonsoluble chromium hydroxide or soluble crystalline hydrates of trivalent chromium. The growth features of these microorganisms on media containing chromate at high concentrations (up to 20.0 g/l) are described. Besides chromate bacteria can reduce vanadate to compounds of V(4+) and Mo(6+) to Mo(5+). The best reduction takes place on the media where MPB. glucose or ethanol serves as the source of carbon. The growth and reduction of anion-in-study did not occur on organic acids. It was shown that tungstate, chlorate or perchlorate were not toxic for the studied bacteria up to concentrations of 10.0 g/l, however were not reduced by these microorganisms. The most active strains belong to genera Pseudomonas, Oerskovia, Bacillus, Micrococcus. PMID:23720958

Smirnova, G F; Podgorski?, V S

2013-01-01

44

Satellite cell mitotic activity in posthatch turkey skeletal muscle growth.  

PubMed

The relationship between satellite cell mitotic activity and skeletal myofiber growth was examined in Pectoralis thoracicus and Biceps femoris muscles of Large White tom turkeys (Nicholas strain) at 3, 6, 9, 18, and 26 wk of age. Mitotically active satellite cells were labeled with 5-bromo-2'-deoxyuridine (BrdU). Labeled satellite cells were identified on enzymatically isolated myofiber segments using mouse anti-BrdU followed by fluorescein-5-isothiocyanate (FITC) conjugated goat anti-mouse IgG secondary antibodies. Myofiber nuclei (satellite cell nuclei + myonuclei) were counterstained with propidium iodide (PI). Myofiber segment diameter, myofiber segment length, and number of FITC- and PI-labeled nuclei were determined for each segment. At each age interval there was an increase in myofiber diameter, suggesting that the myofibers were growing during the entire experimental period. There was an age-related (P < .001) decrease in satellite cell mitotic activity and an age-related increase (P < .001) in the cytoplasmic volume to nucleus ratio (CNR) from 3 to 26 wk of age. An early phase of myofiber growth, between 3 and 6 wk of age, was characterized by a high level of satellite cell mitotic activity and increased CNR. Between 6 and 9 wk of age, satellite cell mitotic activity decreased, but the CNR showed no change (P > .05). During a late phase of myofiber growth, beyond 9 wk of age, satellite cell mitotic activity continued to decrease and myofiber growth occurred by an increased CNR. This study demonstrated that both Pectoralis thoracicus and Biceps femoris undergo a significant late phase of growth without appreciable production of myonuclei by satellite cell proliferation. PMID:8202434

Mozdziak, P E; Schultz, E; Cassens, R G

1994-04-01

45

Mitotic force generators and chromosome segregation  

PubMed Central

The mitotic spindle uses dynamic microtubules and mitotic motors to generate the pico-Newton scale forces that are needed to drive the mitotic movements that underlie chromosome capture, alignment and segregation. Here, we consider the biophysical and molecular basis of force-generation for chromosome movements in the spindle, and, with reference to the Drosophila embryo mitotic spindle, we briefly discuss how mathematical modeling can complement experimental analysis to illuminate the mechanisms of chromosome-to-pole motility during anaphase A and spindle elongation during anaphase B.

Civelekoglu-Scholey, Gul

2010-01-01

46

Mitotic rate in melanoma: a reexamination.  

PubMed

We reexamined the relationship between mitotic rate and overall survival in more than 1,200 cases of cutaneous melanoma with long-term follow-up. Like others, we found that mitotic rate was significantly associated with survival (P < 4 x 10(-8)) and more prognostic than tumor ulceration but was not an independent prognosticator because it was significantly associated with tumor thickness and ulceration. Thus, all 3 histologic variables are interrelated; among these, tumor thickness is the most important. Although mitotic rate can be effectively categorized in 3 groups (1/mm2, 1/mm2(-4)/mm2, and > 4/mm2), the optimal way to use mitotic rate remains unclear, and even this simplification requires determining the raw number per square millimeter. Because the collective information provided by tumor thickness, mitotic rate, ulceration, patient age, and site of tumor about hard outcomes such as 5-year fatality is limited and because measuring mitotic rate requires extra time, we recommend that mitotic rate need not be part of routine reports on cutaneous melanoma. Nevertheless, mitotic rate should continued to be measured in academic centers and other sites that maintain large prospective databases on melanoma, and it should be included in further studies of prognosis and adjuvant therapies for cutaneous melanoma. PMID:17276944

Attis, Maria Gallego; Vollmer, Robin T

2007-03-01

47

Purification and Assay of Mitotic Motors  

PubMed Central

To understand how mitotic kinesins contribute to the assembly and function of the mitotic spindle, we need to purify these motors and analyze their biochemical and ultrastructural properties. Here we briefly review our use of microtubule (MT) affinity and biochemical fractionation to obtain information about the oligomeric state of native mitotic kinesin holoenzymes from eggs and early embryos. We then detail the methods we use to purify full length recombinant Drosophila embryo mitotic kinesins, using the baculovirus expression system, in sufficient yields for detailed in vitro assays. These two approaches provide complementary biochemical information on the basic properties of these key mitotic proteins, and permit assays of critical motor activities, such as MT-MT crosslinking and sliding, that are not revealed by assaying motor domain subfragments.

Tao, Li; Scholey, Jonathan

2013-01-01

48

The Kelch Protein KLHDC8B Guards against Mitotic Errors, Centrosomal Amplification, and Chromosomal Instability  

PubMed Central

The malignant cell in classical Hodgkin lymphoma (HL) is the binucleated giant Reed-Sternberg cell. Chromosomal instability and mitotic errors may contribute to HL pathogenesis; one potential mitotic regulator is the kelch protein KLHDC8B, which localizes to the midbody, is expressed during mitosis, and is mutated in a subset of familial and sporadic HL. We report that disrupting KLHDC8B function in HeLa cells, B lymphoblasts, and fibroblasts leads to significant increases in multinucleation, multipolar mitoses, failed abscission, asymmetric segregation of daughter nuclei, formation of anucleated daughter cells, centrosomal amplification, and aneuploidy. We recapitulated the major pathologic features of the Reed-Sternberg cell and concluded that KLHDC8B is essential for mitotic integrity and maintenance of chromosomal stability. The significant impact of KLHDC8B implicates the central roles of mitotic regulation and chromosomal segregation in the pathogenesis of HL and provides a novel molecular mechanism for chromosomal instability in HL.

Krem, Maxwell M.; Luo, Ping; Ing, Brandon I.; Horwitz, Marshall S.

2012-01-01

49

Highly Nonrandom Features of Synaptic Connectivity in Local Cortical Circuits  

PubMed Central

How different is local cortical circuitry from a random network? To answer this question, we probed synaptic connections with several hundred simultaneous quadruple whole-cell recordings from layer 5 pyramidal neurons in the rat visual cortex. Analysis of this dataset revealed several nonrandom features in synaptic connectivity. We confirmed previous reports that bidirectional connections are more common than expected in a random network. We found that several highly clustered three-neuron connectivity patterns are overrepresented, suggesting that connections tend to cluster together. We also analyzed synaptic connection strength as defined by the peak excitatory postsynaptic potential amplitude. We found that the distribution of synaptic connection strength differs significantly from the Poisson distribution and can be fitted by a lognormal distribution. Such a distribution has a heavier tail and implies that synaptic weight is concentrated among few synaptic connections. In addition, the strengths of synaptic connections sharing pre- or postsynaptic neurons are correlated, implying that strong connections are even more clustered than the weak ones. Therefore, the local cortical network structure can be viewed as a skeleton of stronger connections in a sea of weaker ones. Such a skeleton is likely to play an important role in network dynamics and should be investigated further.

2005-01-01

50

Centromeric Barrier Disruption Leads to Mitotic Defects in Schizosaccharomyces pombe.  

PubMed

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

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

2014-01-01

51

Centromeric Barrier Disruption Leads to Mitotic Defects in Schizosaccharomyces pombe  

PubMed Central

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-ACnp1 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.

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

2014-01-01

52

The Design of High-Level Features for Photo Quality Assessment  

Microsoft Academic Search

We propose a principled method for designing high level features forphoto quality assessment. Our resulting system can classify between high quality professional pho- tos and low quality snapshots. Instead of using the bag of low-level features approach, we first determine the per- ceptual factors that distinguish between professional photos and snapshots. Then, we design high level semantic features to measure

Yan Ke; Xiaoou Tang; Feng Jing

2006-01-01

53

Quantifying mitotic chromosome dynamics and positioning.  

PubMed

The proper organization and segregation of chromosomes during cell division is essential to the preservation of genomic integrity. To understand the mechanisms that spatially control the arrangement and dynamics of mitotic chromosomes requires imaging assays to quantitatively resolve their positions and movements. Here, we will discuss analytical approaches to investigate the position-dependent control of mitotic chromosomes in cultured cells. These methods can be used to dissect the specific contributions of mitotic proteins to the molecular control of chromosome dynamics. J. Cell. Physiol. 229: 1301-1305, 2014. © 2014 Wiley Periodicals, Inc. PMID:24683081

Bissonette, Samantha; Stumpff, Jason

2014-10-01

54

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

PubMed Central

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

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

2008-01-01

55

A comparative evaluation of feature ranking methods for high dimensional bioinformatics data  

Microsoft Academic Search

Feature selection is an important component of data mining analysis with high dimensional data. Reducing the number of features in the dataset can have numerous pos­ itive implications, such as eliminating redundant or irrele­ vant features, decreasing development and improving the performance of classification models. In this work, four filter-based feature selection techniques are compared us­ ing a wide variety

Jason Van Hulse; Taghi M. Khoshgoftaar; Amri Napolitano

2011-01-01

56

Feature-Based Laser Scan Matching For Accurate and High Speed Mobile Robot Localization  

Microsoft Academic Search

This paper introduces an accurate and high speed pose tracking method for mobile robots based on matching of extracted features from consecutive scans. The feature extraction algorithm proposed in this paper uses a global information of the whole scan data and local information around feature points. Uncertainty of each feature is represented using covariance matrices determined due to observation and

Ali Akbar Aghamohammadi; Hamid D. Taghirad; Amir Hossein Tamjidi; E. Mihankhah

2007-01-01

57

A highly scalable incremental facial feature extraction method  

Microsoft Academic Search

Face recognition is one of the most challenging tasks in biometrics, machine vision, and pattern recognition. Methods that can dynamically extract facial features and perform online classification are especially important for real-world applications. The potentially most useful methods in these cases would include incremental learning techniques such as Incremental Principal Component Analysis (IPCA) and Incremental Discriminant Analysis (ILDA). In this

Fengxi Song; Hang Liu; David Zhang; Jing-yu Yang

2008-01-01

58

Mitotic blocking, micronucleation, and chromosome doubling by oryzalin, amiprophos-methyl, and colchicine in potato  

Microsoft Academic Search

Summary The data on mitotic blocking, induction of micronuclei, and chromosome doubling after treatments of transformed potato suspension cells with three different anti-microtubule agents oryzalin, amiprophos-methyl (APM) and colchicine are reported. The fast growing cell suspension line 413 with high mitotic activity is used, which contains various T-DNA introduced genetic markers (kanamycin resistance, ß-glucuronidase activity, hairy root phenotype, hormone autotrophy,

K. Sree Ramulu; H. A. Verhoeven; P. Dijkhuis

1991-01-01

59

A transmembrane inner nuclear membrane protein in the mitotic spindle.  

PubMed

We have recently characterized a novel transmembrane protein of the inner nuclear membrane of mammalian cells. The protein has two very interesting features. First, despite being an integral membrane protein it is able to concentrate in the membranes colocalizing with the mitotic spindle in metaphase and anaphase. Hence, the protein was named Samp1, Spindle associated membrane protein 1. Secondly, it displays a functional connection to centrosomes. This article discusses various aspects of Samp1 in relation to possible cellular function(s). PMID:21327071

Figueroa, Ricardo; Gudise, Santhosh; Larsson, Veronica; Hallberg, Einar

2010-01-01

60

High gas-liquids yield feature of small plant  

SciTech Connect

This paper discusses the gas processing plant in St. Helena Parish, Louisiana that has combined several cryogenic processes into a low volume gas processing system. By utilizing these procedures, a lower temperature has been achieved, resulting in higher liquid recovery. The plant has proven to be an economic improvement to the standard straight refrigeration processing system for low volume gas plants. Several unique features of the plant are: molecular sieve dehydration; J-T (Joule-Thomson) expansion of the refrigerated gas to achieve a lower process temperature, and the recovery of waste heat. The plant's fuel saving design utilizes exhaust heat from the inlet compressor and third-stage gas discharge temperature. The combined processes and fuel savings discussed have eliminated: glycol injection points; glycol three-phase separation; glycol reconcentration; fuel used for glycol reconcentration, and fuel used for product stabilization.

Armellini, T.J.; Baughn, M.

1985-01-07

61

High-speed, sub-15 nm feature size thermochemical nanolithography  

NASA Astrophysics Data System (ADS)

The past decade has witnessed an explosion of techniques used to pattern materials on the nano and submicrometer scale, driven by a diversity of applications, such as molecular electronics, data storage, optoelectronics, displays, and all forms of sensors. However, there are many challenges to conventional techniques as they are approaching their fundamental size limit. Here we report a nanolithography technique that allows simultaneous direct control of the local chemistry and topography of thin polymer films. Specifically, a heated atomic force microscope tip can write sub-15 nanometer hydrophilic features over a hydrophobic polymer at the rate of 1.4 millimeters per second. This method is simple, direct, extremely rapid, achievable in a range of environments, and easily adaptable to other materials systems.

Riedo, Elisa; Szoszkiewicz, Robert; Okada, Takashi; Jones, Simon; Li, Tai-De; King, William; Marder, Seth

2007-03-01

62

Physicochemical features of ultra-high viscosity alginates  

Microsoft Academic Search

The physicochemical characteristics of the ultra-high viscosity and highly biocompatible alginates extracted from Lessonia nigrescens (UHVN) and Lessonia trabeculata (UHVT) were analyzed. Fluorescence and 1H NMR spectroscopies, viscometry, and multi-angle light scattering (MALS) were used for elucidation of the chemical structure, molar mass, and coil size. The sequential structures from NMR spectroscopy showed high guluronate content for UHVT, but low

Henning Storz; Kilian J. Müller; Friederike Ehrhart; Ivan Gómez; Stephen G. Shirley; Petra Gessner; Gertraud Zimmermann; Esther Weyand; Vladimir L. Sukhorukov; Thomas Forst; Matthias M. Weber; Heiko Zimmermann; Werner-Michael Kulicke; Ulrich Zimmermann

2009-01-01

63

High manufacturability Cu multilevel interconnects featuring hybrid-NCS structure  

Microsoft Academic Search

We developed a 65-nm CMOS technology that could successfully integrate a novel porous low-k material, NCS. Using our nano-clustering technique, we obtained that NCS had a high compatibility between a very low dielectric constant and high framework strength. We successfully fabricated 11-levels Cu interconnects using hybrid-NCS structure. These interconnects had a high tolerance to the etching process and produced a

I. Sugiura; N. Misawa; S. Otsuka; N. Nishikawa; Y. Iba; F. Sugimoto; Y. Setta; H. Sakai; Y. Koura; K. Nakano; T. Karasawa; Y. Ohkura; T. Kouno; H. Watatani; Y. Nakata; Y. Mizushima; T. Suzuki; H. Kitada; N. Shimizu; S. Nakai; M. Nakaishi; S. Fukuyama; T. Nakamura; E. Yano; M. Miyajima; K. Watanabe

2005-01-01

64

Inversion Method Study on Short Wave Infrared Remote Sensing Data High Temperature Surface Feature Temperature  

Microsoft Academic Search

The short wave infrared remote sensing data element DN value is synthesis reflectance of surface features reflex and the emission energy that the emission energy can be ignored generally in terms of the normal temperature surface features, but emission energy of the high temperature surface feature is close or higher than its reflex energy value, based on this, using the

Pan Jun; Xing Li-xin; Wen Jiu-cheng; Meng Tao; Jiang Li-jun

2009-01-01

65

A mitotic recombination system for mouse chromosome 17  

PubMed Central

Mitotic recombination between homologous chromosomes is a genetic technique for mosaic analysis in model organisms. The general application of this technique in the mouse depends on establishment of effective recombination systems for individual chromosomes and reliable and sensitive methods for detection of recombination events. Here, we established a Cre/LoxP-mediated recombination system in mice for mosaic analysis of full-length chromosome 17. Cre-mediated germ-line recombination between the homologous chromosomes was observed with ?9% frequency in a progeny test. Mitotic recombination in somatic tissues was evaluated and scored in B and T lymphocytes with the aid of surface markers and fluorescent-activated cell sorting. We show that a lineage-specific Cre can induce mitotic recombination with a highly reproducible frequency of 0.5–1.0% in lymphoid progenitors. The recombination system established here allows for a simple and accurate detection and isolation of recombination events in live cells, making this system particularly attractive for mosaic analysis or mutagenesis studies in the immune system.

Sun, Lei; Wu, Xiaohui; Han, Min; Xu, Tian; Zhuang, Yuan

2008-01-01

66

Survivin deregulation in beta-tubulin mutant ovarian cancer cells underlies their compromised mitotic response to taxol.  

PubMed

Taxol is one of the most successful drugs for the treatment of cancer because of its ability to target tubulin, block cell cycle progression at mitosis, and induce apoptosis. Despite the success of Taxol, the development of drug resistance hampers its clinical applicability. Herein we report that beta-tubulin mutant, Taxol-resistant ovarian cancer cells exhibit defective mitotic response to Taxol, even at high concentrations that are sufficient to trigger apoptosis. This mitotic response-defective phenotype is independent of p53 status. We have found that survivin, the mitosis regulator and inhibitor of apoptosis protein, is deregulated in these Taxol-resistant cancer cells; Taxol fails to induce survivin levels and survivin phosphorylation in these cells, in contrast to their parental drug-sensitive counterparts. Exogenous expression of wild-type survivin is able to restore the mitotic response of the resistant cells to Taxol treatment. On the other hand, exogenous expression of dominant-negative survivin abrogates the Taxol-induced mitotic response in drug-sensitive cancer cells. We have also found that overexpression of the mitotic kinase Cdk1, which phosphorylates survivin, is unable to restore the Taxol-induced mitotic response in the resistant cells. Our results show the importance of survivin for the mitotic response in the context of Taxol resistance and provide novel insights into the mechanisms of mitotic arrest and apoptosis induced by microtubule-targeting agents. PMID:15574781

Zhou, Jun; O'brate, Aurora; Zelnak, Amelia; Giannakakou, Paraskevi

2004-12-01

67

Mitotic responses to injected extracts of larval and adult Schistosoma mansoni in Biomphalaria glabrata: effects of dose and colchicine treatment.  

PubMed

Biomphalaria glabrata snails injected with extracts of Schistosoma mansoni miracidia, mother sporocyst excretory-secretory product, cercariae, and adults, showed increased mitotic activity in histological sections of the amebocyte-producing organ (APO) relative to water-injected controls. The mitotic response was generally higher to extracts adjusted to 1.0 mg protein/ml than to a 10-fold lower concentration, although in most cases this increase was not statistically significant. Colchicine treatment prior to fixation significantly increased the number of mitotic figures in APOs of all groups of extract-injected snails, both with respect to water-injected controls and, with 1 exception, relative to matched colchicine-untreated snails. Extracts of adult worms elicited a pronounced mitotic response, suggesting that adults may share a mitogenic molecule with larvae. The high variability in counts of mitotic figures may limit the usefulness of this histological method. PMID:17436970

Sullivan, John T

2007-02-01

68

Robust linear regression model of Ki-67 for mitotic rate in gastrointestinal stromal tumors  

PubMed Central

Risk stratification of gastrointestinal stromal tumors (GISTs) by tumor size, lymph node and metastasis status is crucially affected by mitotic activity. To date, no studies have quantitatively compared mitotic activity in hematoxylin and eosin (H&E)-stained tissue sections with immunohistochemical markers, such as phosphohistone H3 (PHH3) and Ki-67. According to the TNM guidelines, the mitotic count on H&E sections and immunohistochemical PHH3-stained slides has been assessed per 50 high-power fields of 154 specimens of clinically documented GIST cases. The Ki-67-associated proliferation rate was evaluated on three digitalized hot spots using image analysis. The H&E-based mitotic rate was found to correlate significantly better with Ki-67-assessed proliferation activity than with PHH3-assessed proliferation activity (r=0.780; P<0.01). A linear regression model (analysis of variance; P<0.001) allowed reliable predictions of the H&E-associated mitoses based on the Ki-67 expression alone. Additionally, the Ki-67-associated proliferation revealed a higher and significant impact on the recurrence and metastasis rate of the GIST cases than by the classical H&E-based mitotic rate. The results of the present study indicated that the mitotic rate may be reliably and time-efficiently estimated by immunohistochemistry of Ki-67 using only three hot spots.

KEMMERLING, RALF; WEYLAND, DENIS; KIESSLICH, TOBIAS; ILLIG, ROMANA; KLIESER, ECKHARD; JAGER, TARKAN; DIETZE, OTTO; NEUREITER, DANIEL

2014-01-01

69

Physical Features of the Connecticut River Outflow During High Discharge  

Microsoft Academic Search

The outflow of the Connecticut River into eastern Long Island Sound was studied during periods of high discharge. Surface measurements as well as aerial photography were employed to determine the primary physical characteristics of the outflow and its path within Long Island Sound. The structure of the outflow at the mouth was found to approach that of the salt wedge

Richard W. Garvine

1974-01-01

70

Sound insulating element featuring high stiffness and low weight  

Microsoft Academic Search

This paper describes a new approach to the problem of combining good sound insulation with high stiffness, low weight and limited thickness. A typical application is shipboard partitions where weight and thickness are essential cost factors and where specified demands on sound insulation are made at an increasing rate. A single leaf wall will as we know under favorable conditions

S. Einarsson; J. Soederquist

1982-01-01

71

Distinctive features of corrosion cracking of high-strength steels  

Microsoft Academic Search

Experimental data on the corrosion cracking resistance of high-strength steel with a yield limit s0.2 ? 1000 MPa in 3.5 % NaCl solution are presented. It is shown that cracking resistance can be estimated by using the so-called net rated fracture stresses. Corrosion cracking in the surface layers of the metal operating in contact with the medium is explained by

V. N. Malyshev; V. V. Potapov

1995-01-01

72

Distinctive features of corrosion cracking of high-strength steels  

Microsoft Academic Search

Experimental data on the corrosion cracking resistance of high-strength steel with a yield limit Ï{sub 0.2}â 1000 MPa in 3.5% NaCl solution are presented. It is shown that cracking resistance can be estimated by using the so-called net rated fracture stresses. Corrosion cracking in the surface layers of the metal operating in contact with the medium is explained by the

V. N. Malyshev; V. V. Potapov

1994-01-01

73

Increased mitotic and proliferative activity are associated with worse prognosis in papillary tumors of the pineal region.  

PubMed

Papillary tumors of the pineal region are rare glial tumors located in the vicinity of the third ventricle, the clinical behavior of which is often aggressive. Little is known about the prognostic markers that might aid to identify patients at increased risk for recurrence. Therefore, the prognostic value of histopathologic and clinical features was examined in a series of 21 patients. Median age of the 12 male and 9 female patients was 35 years (range, 10 to 56 y). On histopathologic examination, all tumors were characterized by loose papillary structures and tumor cells forming broad perivascular pseudorosettes showing cytokeratin expression. In addition, tumors showed increased cellularity (n=4; 19%), nuclear pleomorphism (n=4; 19%), solid growth (n=11; 52%), necrosis (n=8; 38%), increased mitotic activity (?3 mitoses per 10 high-power fields [n=10; 48%]), and increased proliferation (Ki67/MIB1 index ?10% [n=8/20; 40%]). Gross total resection could be achieved in 13/21 patients (62%). Postoperatively, 13 patients received radiotherapy and 4 patients chemotherapy. Median recurrence-free survival was 66 months in 19 patients, for whom detailed follow-up information was available. Twelve patients (63%) experienced tumor progression. Three patients (16%) died of disease. Among the clinical and histopathologic features examined, only increased mitotic activity (52 [8 to 96] vs. 68 [66 to 70] mo [median [95% confidence interval

Heim, Stephanie; Beschorner, Rudi; Mittelbronn, Michel; Keyvani, Kathy; Riemenschneider, Markus J; Vajtai, Istvan; Hartmann, Christian; Acker, Till; Blümcke, Ingmar; Paulus, Werner; Hasselblatt, Martin

2014-01-01

74

Fluorescent in situ hybridization on mitotic chromosomes of mosquitoes.  

PubMed

Fluorescent in situ hybridization (FISH) is a technique routinely used by many laboratories to determine the chromosomal position of DNA and RNA probes. One important application of this method is the development of high-quality physical maps useful for improving the genome assemblies for various organisms. The natural banding pattern of polytene and mitotic chromosomes provides guidance for the precise ordering and orientation of the genomic supercontigs. Among the three mosquito genera, namely Anopheles, Aedes, and Culex, a well-established chromosome-based mapping technique has been developed only for Anopheles, whose members possess readable polytene chromosomes. As a result of genome mapping efforts, 88% of the An. gambiae genome has been placed to precise chromosome positions. Two other mosquito genera, Aedes and Culex, have poorly polytenized chromosomes because of significant overrepresentation of transposable elements in their genomes. Only 31 and 9% of the genomic supercontings have been assigned without order or orientation to chromosomes of Ae. aegypti and Cx. quinquefasciatus, respectively. Mitotic chromosome preparation for these two species had previously been limited to brain ganglia and cell lines. However, chromosome slides prepared from the brain ganglia of mosquitoes usually contain low numbers of metaphase plates. Also, although a FISH technique has been developed for mitotic chromosomes from a cell line of Ae. aegypti, the accumulation of multiple chromosomal rearrangements in cell line chromosomes makes them useless for genome mapping. Here we describe a simple, robust technique for obtaining high-quality mitotic chromosome preparations from imaginal discs (IDs) of 4th instar larvae which can be used for all three genera of mosquitoes. A standard FISH protocol is optimized for using BAC clones of genomic DNA as a probe on mitotic chromosomes of Ae. aegypti and Cx. quinquefasciatus, and for utilizing an intergenic spacer (IGS) region of ribosomal DNA (rDNA) as a probe on An. gambiae chromosomes. In addition to physical mapping, the developed technique can be applied to population cytogenetics and chromosome taxonomy/systematics of mosquitoes and other insect groups. PMID:23007640

Timoshevskiy, Vladimir A; Sharma, Atashi; Sharakhov, Igor V; Sharakhova, Maria V

2012-01-01

75

Fluorescent in situ Hybridization on Mitotic Chromosomes of Mosquitoes  

PubMed Central

Fluorescent in situ hybridization (FISH) is a technique routinely used by many laboratories to determine the chromosomal position of DNA and RNA probes. One important application of this method is the development of high-quality physical maps useful for improving the genome assemblies for various organisms. The natural banding pattern of polytene and mitotic chromosomes provides guidance for the precise ordering and orientation of the genomic supercontigs. Among the three mosquito genera, namely Anopheles, Aedes, and Culex, a well-established chromosome-based mapping technique has been developed only for Anopheles, whose members possess readable polytene chromosomes 1. As a result of genome mapping efforts, 88% of the An. gambiae genome has been placed to precise chromosome positions 2,3 . Two other mosquito genera, Aedes and Culex, have poorly polytenized chromosomes because of significant overrepresentation of transposable elements in their genomes 4, 5, 6. Only 31 and 9% of the genomic supercontings have been assigned without order or orientation to chromosomes of Ae. aegypti 7 and Cx. quinquefasciatus 8, respectively. Mitotic chromosome preparation for these two species had previously been limited to brain ganglia and cell lines. However, chromosome slides prepared from the brain ganglia of mosquitoes usually contain low numbers of metaphase plates 9. Also, although a FISH technique has been developed for mitotic chromosomes from a cell line of Ae. aegypti 10, the accumulation of multiple chromosomal rearrangements in cell line chromosomes 11 makes them useless for genome mapping. Here we describe a simple, robust technique for obtaining high-quality mitotic chromosome preparations from imaginal discs (IDs) of 4th instar larvae which can be used for all three genera of mosquitoes. A standard FISH protocol 12 is optimized for using BAC clones of genomic DNA as a probe on mitotic chromosomes of Ae. aegypti and Cx. quinquefasciatus, and for utilizing an intergenic spacer (IGS) region of ribosomal DNA (rDNA) as a probe on An. gambiae chromosomes. In addition to physical mapping, the developed technique can be applied to population cytogenetics and chromosome taxonomy/systematics of mosquitoes and other insect groups.

Timoshevskiy, Vladimir A.; Sharma, Atashi; Sharakhov, Igor V.; Sharakhova, Maria V.

2012-01-01

76

Identification of small molecule inhibitors of the mitotic kinase haspin by high-throughput screening using a homogeneous time-resolved fluorescence resonance energy transfer assay.  

PubMed

Haspin/Gsg2 is a kinase that phosphorylates histone H3 at Thr-3 (H3T3ph) during mitosis. Its depletion by RNA interference results in failure of chromosome alignment and a block in mitosis. Haspin, therefore, is a novel target for development of antimitotic agents. We report the development of a high-throughput time-resolved fluorescence resonance energy transfer (TR-FRET) kinase assay for haspin. Histone H3 peptide was used as a substrate, and a europium-labeled H3T3ph phosphospecific monoclonal antibody was used to detect phosphorylation. A library of 137632 small molecules was screened at K(m) concentrations of ATP and peptide to allow identification of diverse inhibitor types. Reconfirmation of hits and IC( 50) determinations were carried out with the TR-FRET assay and by a radiometric assay using recombinant histone H3 as the substrate. A preliminary assessment of specificity was made by testing inhibition of 2 unrelated kinases. EC( 50) values in cells were determined using a cell-based ELISA of H3T3ph. Five compounds were selected as leads based on potency and chemical structure considerations. These leads form the basis for the development of specific inhibitors of haspin that will have clear utility in basic research and possible use as starting points for development of antimitotic anticancer therapeutics. PMID:18978305

Patnaik, Debasis; Jun Xian; Glicksman, Marcie A; Cuny, Gregory D; Stein, Ross L; Higgins, Jonathan M G

2008-12-01

77

Video Retrieval Using High Level Features: Exploiting Query Matching and Confidence-Based Weighting  

Microsoft Academic Search

Recent research in video retrieval has focused on automated, high- level feature indexing on shots or frames. One important application of such indexing is to support precise video retrieval. We report on extensions of this semantic indexing on news video retrieval. First, we utilize extensive query anal- ysis to relate various high-level features and query terms by matching the tex-

Shi-yong Neo; Jin Zhao; Min-yen Kan; Tat-seng Chua

2006-01-01

78

Analysis of mitosis and anti-mitotic drug responses in tumors by in vivo microscopy and single-cell pharmacodynamics  

PubMed Central

Cancer relies upon frequent or abnormal cell division but how the tumor microenvironment affects mitotic processes in vivo remains unclear, largely due to the technical challenges of optical access, spatial resolution, and motion. We developed high-resolution in vivo microscopy methods to visualize mitosis in a murine xenograft model of human cancer. Using these methods, we determined whether the single-cell response to the anti-mitotic drug paclitaxel was the same in tumors as in cell culture; observed the impact of paclitaxel (Ptx) on the tumor response as a whole; and evaluated the single-cell pharmacodynamics of paclitaxel (by in vivo pharmacodynamic microscopy [IPDM]). Mitotic initiation was generally less frequent in tumors than in cell culture, but subsequently it proceeded normally. Paclitaxel treatment caused spindle assembly defects and mitotic arrest, followed by slippage from mitotic arrest, multinucleation and apoptosis. Compared to cell culture, the peak mitotic index in tumors exposed to paclitaxel was lower and the tumor cells survived longer after mitotic arrest, becoming multinucleated rather than dying directly from mitotic arrest. Thus, the tumor microenvironment was much less pro-apoptotic than cell culture. The morphologies associated with mitotic arrest were dose- and time-dependent, thereby providing a semi-quantitative, single-cell measure of pharmacodynamics. Although many tumor cells did not progress through Ptx-induced mitotic arrest, tumor significantly regressed in the model. Our findings demonstrate that in vivo microscopy offers a useful tool to visualize mitosis during tumor progression, drug responses, and cell fate at the single cell level.

Orth, J.D.; Kohler, R.H.; Foijer, F; Sorger, P.K.; Weissleder, R.; Mitchison, T.J.

2011-01-01

79

Rapid measurement of mitotic spindle orientation in cultured mammalian cells  

PubMed Central

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

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

2014-01-01

80

Feature Modelling of High Resolution Remote Sensing Images Considering Spatial Autocorrelation  

NASA Astrophysics Data System (ADS)

To deal with the problem of spectral variability in high resolution satellite images, this paper focuses on the analysis and modelling of spatial autocorrelation feature. The semivariograms are used to model spatial variability of typical object classes while Getis statistic is used for the analysis of local spatial autocorrelation within the neighbourhood window determined by the range information of the semivariograms. Two segmentation experiments are conducted via the Fuzzy C-Means (FCM) algorithm which incorporates both spatial autocorrelation features and spectral features, and the experimental results show that spatial autocorrelation features can effectively improve the segmentation quality of high resolution satellite images.

Chen, Y. X.; Qin, K.; Liu, Y.; Gan, S. Z.; Zhan, Y.

2012-08-01

81

Zygotic development without functional mitotic centrosomes  

Microsoft Academic Search

The centrosome is the dominant microtubule-organizing center in animal cells. At the onset of mitosis, each cell normally has two centrosomes that lie on opposite sides of the nucleus. Centrosomes nucleate the growth of microtubules and orchestrate the efficient assembly of the mitotic spindle. Recent studies in vivo and in vitro have shown that the spindle can form even in

Timothy L Megraw; Ling-Rong Kao; Thomas C Kaufman

2001-01-01

82

Phosphoproteome analysis of the human mitotic spindle  

PubMed Central

During cell division, the mitotic spindle segregates the sister chromatids into two nascent cells, such that each daughter cell inherits one complete set of chromosomes. Errors in spindle formation can result in both chromosome missegregation and cytokinesis defects and hence lead to genomic instability. To ensure the correct function of the spindle, the activity and localization of spindle associated proteins has to be tightly regulated in time and space. Reversible phosphorylation has been shown to be one of the key regulatory mechanisms for the organization of the mitotic spindle. The relatively low number of identified in vivo phosphorylation sites of spindle components, however, has hampered functional analysis of regulatory spindle networks. A more complete inventory of the phosphorylation sites of spindle-associated proteins would therefore constitute an important advance. Here, we describe the mass spectrometry-based identification of in vivo phosphorylation sites from purified human mitotic spindles. In total, 736 phosphorylation sites were identified, of which 312 could be attributed to known spindle proteins. Among these are phosphorylation sites that were previously shown to be important for the regulation of spindle-associated proteins. Importantly, this data set also comprises 279 novel phosphorylation sites of known spindle proteins for future functional studies. This inventory of spindle phosphorylation sites should thus make an important contribution to a better understanding of the molecular mechanisms that regulate the formation, function, and integrity of the mitotic spindle.

Nousiainen, Marjaana; Sillje, Herman H. W.; Sauer, Guido; Nigg, Erich A.; Korner, Roman

2006-01-01

83

Mitotic Stress and Chromosomal Instability in Cancer  

PubMed Central

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

Malumbres, Marcos

2012-01-01

84

Identification of Drosophila Mitotic Genes by Combining Co-Expression Analysis and RNA Interference  

PubMed Central

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.

Somma, Maria Patrizia; Ceprani, Francesca; Bucciarelli, Elisabetta; Naim, Valeria; De Arcangelis, Valeria; Piergentili, Roberto; Palena, Antonella; Ciapponi, Laura; Giansanti, Maria Grazia; Pellacani, Claudia; Petrucci, Romano; Cenci, Giovanni; Verni, Fiammetta; Fasulo, Barbara; Goldberg, Michael L.; Di Cunto, Ferdinando; Gatti, Maurizio

2008-01-01

85

Non-iridescent Transmissive Structural Color Filter Featuring Highly Efficient Transmission and High Excitation Purity.  

PubMed

Nanostructure based color filtering has been considered an attractive replacement for current colorant pigmentation in the display technologies, in view of its increased efficiencies, ease of fabrication and eco-friendliness. For such structural filtering, iridescence relevant to its angular dependency, which poses a detrimental barrier to the practical development of high performance display and sensing devices, should be mitigated. We report on a non-iridescent transmissive structural color filter, fabricated in a large area of 76.2 × 25.4?mm(2), taking advantage of a stack of three etalon resonators in dielectric films based on a high-index cavity in amorphous silicon. The proposed filter features a high transmission above 80%, a high excitation purity of 0.93 and non-iridescence over a range of 160°, exhibiting no significant change in the center wavelength, dominant wavelength and excitation purity, which implies no change in hue and saturation of the output color. The proposed structure may find its potential applications to large-scale display and imaging sensor systems. PMID:24815530

Shrestha, Vivek Raj; Lee, Sang-Shin; Kim, Eun-Soo; Choi, Duk-Yong

2014-01-01

86

Non-iridescent Transmissive Structural Color Filter Featuring Highly Efficient Transmission and High Excitation Purity  

NASA Astrophysics Data System (ADS)

Nanostructure based color filtering has been considered an attractive replacement for current colorant pigmentation in the display technologies, in view of its increased efficiencies, ease of fabrication and eco-friendliness. For such structural filtering, iridescence relevant to its angular dependency, which poses a detrimental barrier to the practical development of high performance display and sensing devices, should be mitigated. We report on a non-iridescent transmissive structural color filter, fabricated in a large area of 76.2 × 25.4 mm2, taking advantage of a stack of three etalon resonators in dielectric films based on a high-index cavity in amorphous silicon. The proposed filter features a high transmission above 80%, a high excitation purity of 0.93 and non-iridescence over a range of 160°, exhibiting no significant change in the center wavelength, dominant wavelength and excitation purity, which implies no change in hue and saturation of the output color. The proposed structure may find its potential applications to large-scale display and imaging sensor systems.

Shrestha, Vivek Raj; Lee, Sang-Shin; Kim, Eun-Soo; Choi, Duk-Yong

2014-05-01

87

Non-iridescent Transmissive Structural Color Filter Featuring Highly Efficient Transmission and High Excitation Purity  

PubMed Central

Nanostructure based color filtering has been considered an attractive replacement for current colorant pigmentation in the display technologies, in view of its increased efficiencies, ease of fabrication and eco-friendliness. For such structural filtering, iridescence relevant to its angular dependency, which poses a detrimental barrier to the practical development of high performance display and sensing devices, should be mitigated. We report on a non-iridescent transmissive structural color filter, fabricated in a large area of 76.2 × 25.4?mm2, taking advantage of a stack of three etalon resonators in dielectric films based on a high-index cavity in amorphous silicon. The proposed filter features a high transmission above 80%, a high excitation purity of 0.93 and non-iridescence over a range of 160°, exhibiting no significant change in the center wavelength, dominant wavelength and excitation purity, which implies no change in hue and saturation of the output color. The proposed structure may find its potential applications to large-scale display and imaging sensor systems.

Shrestha, Vivek Raj; Lee, Sang-Shin; Kim, Eun-Soo; Choi, Duk-Yong

2014-01-01

88

Mitotic errors, aneuploidy and micronuclei in Hodgkin lymphoma pathogenesis.  

PubMed

The Reed-Sternberg (RS) cell is the driving force behind Hodgkin lymphoma (HL), a unique malignancy in which the rare RS cell creates an inflammatory microenvironment that recruits a reactive tumor infiltrate. Well-known oncogenic factors such as nuclear factor kappa B (NF?B) signaling and Epstein-Barr virus infection are linked to HL pathogenesis but do not adequately explain the RS cell's key pathologic features of multi-nucleation, abnormalities of centrosome function and number and aneuploidy. Chromosomal instability is also considered a key pathway in the origin of the RS cell, though the molecular mechanisms have largely been a "black box." We demonstrated that the midbody kelch domain protein KLHDC8B protects against mitotic errors, centrosomal amplification and chromosomal instability. Here we discuss how the new findings linking KLHDC8B to mitotic integrity and faithful chromosomal segregation are providing mechanistic explanations for the origin of the RS cell and the molecular pathogenesis of chromosomal instability in HL. PMID:23713010

Krem, Maxwell M; Horwitz, Marshall S

2013-05-01

89

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

PubMed

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-?C795 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. PMID:21637791

Dayani, Yaron; Simchen, Giora; Lichten, Michael

2011-05-01

90

Comparative analysis of mitosis-specific antibodies for bulk purification of mitotic populations by fluorescence-activated cell sorting  

PubMed Central

Mitosis entails complex chromatin changes that have garnered increasing interest from biologists who study genome structure and regulation – fields that are being advanced by high-throughput sequencing (Seq) technologies. The application of such technologies to study the mitotic genome requires large numbers of highly pure mitotic cells with minimal contamination from interphase cells to ensure accurate measurements of phenomena specific to mitosis. Here, we optimized a fluorescence-activated cell sorting (FACS)-based method for isolating formaldehyde-fixed mitotic cells – at virtually 100% mitotic purity – in substantial quantities sufficient for high-throughput genomic studies. We compare several commercially available antibodies that react with mitosis-specific epitopes over a range of concentrations and cell numbers, and identify antibody MPM2 as the most robust and cost-effective.

Blobel, Gerd A.

2014-01-01

91

EGF-induced centrosome separation promotes mitotic progression and cell survival.  

PubMed

Timely and accurate assembly of the mitotic spindle is critical for the faithful segregation of chromosomes, and centrosome separation is a key step in this process. The timing of centrosome separation varies dramatically between cell types; however, the mechanisms responsible for these differences and its significance are unclear. Here, we show that activation of epidermal growth factor receptor (EGFR) signaling determines the timing of centrosome separation. Premature separation of centrosomes decreases the requirement for the major mitotic kinesin Eg5 for spindle assembly, accelerates mitosis, and decreases the rate of chromosome missegregation. Importantly, EGF stimulation impacts upon centrosome separation and mitotic progression to different degrees in different cell lines. Cells with high EGFR levels fail to arrest in mitosis upon Eg5 inhibition. This has important implications for cancer therapy because cells with high centrosomal response to EGF are more susceptible to combinatorial inhibition of EGFR and Eg5. PMID:23643362

Mardin, Balca R; Isokane, Mayumi; Cosenza, Marco R; Krämer, Alwin; Ellenberg, Jan; Fry, Andrew M; Schiebel, Elmar

2013-05-13

92

Automatic target recognition of radar HRRP based on high order central moments features  

Microsoft Academic Search

The paper addresses the problem of target recognition using High-resolution Radar Range Profiles (HRRP). A novel approach\\u000a of feature extraction and dimension reduction based on extended high order central moments is proposed in order to reduce\\u000a the dimension of range profiles. Features extracted from radar HRRPs are normalized and smoothed, and then comparative analysis\\u000a of the similar approaches is done.

Luo Si Li Shaohong; Shaohong Li

2009-01-01

93

Sternum Image Retrieval Based on High-level Semantic Information and Low-level Features  

Microsoft Academic Search

In allusion to sternum images, herein we describe a system which supports image retrieval by content. Attention is focused on high-level semantic information representation of medical images. Then a feature fusion algorithm of medical image retrieval using high-level semantic information combining low-level features is presented. A prototype system which supports query by example is designed and implemented on vista operating

Qin Chen; Xiaoying Tai

2008-01-01

94

Death through a tragedy: mitotic catastrophe.  

PubMed

Mitotic catastrophe (MC) has long been considered as a mode of cell death that results from premature or inappropriate entry of cells into mitosis and can be caused by chemical or physical stresses. Whereas it initially was depicted as the main form of cell death induced by ionizing radiation, it is today known to be triggered also by treatment with agents influencing the stability of microtubule, various anticancer drugs and mitotic failure caused by defective cell cycle checkpoints. Although various descriptions explaining MC exist, there is still no general accepted definition of this phenomenon. Here, we present evidences indicating that death-associated MC is not a separate mode of cell death, rather a process ('prestage') preceding cell death, which can occur through necrosis or apoptosis. The final outcome of MC depends on the molecular profile of the cell. PMID:18404154

Vakifahmetoglu, H; Olsson, M; Zhivotovsky, B

2008-07-01

95

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

PubMed Central

Fisetin is a natural flavonol present in edible vegetables, fruits and wine at 2–160 ?g/g concentrations and an ingredient in nutritional supplements with much higher concentrations. The compound has been reported to exert anticarcinogenic effects as well as antioxidant and anti-inflammatory activity via its ability to act as an inhibitor of cell proliferation and free radical scavenger, respectively. Our cell-based high-throughput screen for small molecules that override chemically induced mitotic arrest identified fisetin as an antimitotic compound. Fisetin rapidly compromised microtubule drug-induced mitotic block in a proteasome-dependent manner in several human cell lines. Moreover, in unperturbed human cancer cells fisetin caused premature initiation of chromosome segregation and exit from mitosis without normal cytokinesis. To understand the molecular mechanism behind these mitotic errors, we analyzed the consequences of fisetin treatment on the localization and phoshorylation of several mitotic proteins. Aurora B, Bub1, BubR1 and Cenp-F rapidly lost their kinetochore/centromere localization and others became dephosphorylated upon addition of fisetin to the culture medium. Finally, we identified Aurora B kinase as a novel direct target of fisetin. The activity of Aurora B was significantly reduced by fisetin in vitro and in cells, an effect that can explain the observed forced mitotic exit, failure of cytokinesis and decreased cell viability. In conclusion, our data propose that fisetin perturbs spindle checkpoint signaling, which may contribute to the antiproliferative effects of the compound.

Salmela, Anna-Leena; Pouwels, Jeroen; Varis, Asta; Kukkonen, Anu M.; Toivonen, Pauliina; Halonen, Pasi K.; Perala, Merja; Kallioniemi, Olli; Gorbsky, Gary J.; Kallio, Marko J.

2009-01-01

96

The relative effect of citral on mitotic microtubules in wheat roots and BY2 cells.  

PubMed

The plant volatile monoterpene citral is a highly active compound with suggested allelopathic traits. Seed germination and seedling development are inhibited in the presence of citral, and it disrupts microtubules in both plant and animal cells in interphase. We addressed the following additional questions: can citral interfere with cell division; what is the relative effect of citral on mitotic microtubules compared to interphase cortical microtubules; what is its effect on newly formed cell plates; and how does it affect the association of microtubules with ?-tubulin? In wheat seedlings, citral led to inhibition of root elongation, curvature of newly formed cell walls and deformation of microtubule arrays. Citral's effect on microtubules was both dose- and time-dependent, with mitotic microtubules appearing to be more sensitive to citral than cortical microtubules. Association of ?-tubulin with microtubules was more sensitive to citral than were the microtubules themselves. To reveal the role of disrupted mitotic microtubules in dictating aberrations in cell plates in the presence of citral, we used tobacco BY2 cells expressing GFP-Tua6. Citral disrupted mitotic microtubules, inhibited the cell cycle and increased the frequency of asymmetric cell plates in these cells. The time scale of citral's effect in BY2 cells suggested a direct influence on cell plates during their formation. Taken together, we suggest that at lower concentrations, citral interferes with cell division by disrupting mitotic microtubules and cell plates, and at higher concentrations it inhibits cell elongation by disrupting cortical microtubules. PMID:22039835

Chaimovitsh, D; Rogovoy Stelmakh, O; Altshuler, O; Belausov, E; Abu-Abied, M; Rubin, B; Sadot, E; Dudai, N

2012-03-01

97

Tissue-specific Mitotic Bookmarking by Hematopoietic Transcription Factor GATA1  

PubMed Central

Summary Tissue-specific transcription patterns are preserved throughout cell divisions to maintain lineage fidelity. We investigated whether transcription factor GATA1 plays a role in transmitting hematopoietic gene expression programs through mitosis when transcription is transiently silenced. Live cell imaging revealed that a fraction of GATA1 is retained focally within mitotic chromatin. ChIP-seq of highly purified mitotic cells uncovered that key hematopoietic regulatory genes are occupied by GATA1 in mitosis. The GATA1 co-regulators FOG1 and TAL1 dissociate from mitotic chromatin, suggesting that GATA1 functions as platform for their postmitotic recruitment. Mitotic GATA1 target genes tend to re-activate more rapidly upon entry into G1 than genes from which GATA1 dissociates. Mitosis-specific destruction of GATA1 delays reactivation selectively of genes that retain GATA1 during mitosis. These studies suggest a requirement of mitotic “bookmarking” by GATA1 for the faithful propagation of cell type-specific transcription programs through cell division.

Kadauke, Stephan; Udugama, Maheshi I.; Pawlicki, Jan M.; Achtman, Jordan C.; Jain, Deepti P.; Cheng, Yong; Hardison, Ross C.; Blobel, Gerd A.

2012-01-01

98

Higher-order structure of human mitotic chromosomes.  

PubMed

From observations on the partial disintegration of isolated human metaphase chromosomes we propose that human metaphase chromatids have a rather simple organization based on the folding and coiling of a long, regular, hollow cylindrical structure with a diameter of about 4000 A. This cylindrical structure, the unit fiber, is postulated to be a super-solenoid formed by the coiling of a 300 A solenoid, itself composed by coiling the basic string of nucleosomes. The structure of a human chromatid would thus be a hierarchy of helices, the contraction ratio of each coil, in ascending order of size, being approximately 7, 6, 40, and 5. This model appears to explain the estimated mass/unit length and accounts for many of the known features of human mitotic chromatids. PMID:266199

Bak, A L; Zeuthen, J; Crick, F H

1977-04-01

99

Prime movers: the mechanochemistry of mitotic kinesins.  

PubMed

Mitotic spindles are self-organizing protein machines that harness teams of multiple force generators to drive chromosome segregation. Kinesins are key members of these force-generating teams. Different kinesins walk directionally along dynamic microtubules, anchor, crosslink, align and sort microtubules into polarized bundles, and influence microtubule dynamics by interacting with microtubule tips. The mechanochemical mechanisms of these kinesins are specialized to enable each type to make a specific contribution to spindle self-organization and chromosome segregation. PMID:24651543

Cross, Robert A; McAinsh, Andrew

2014-04-01

100

Two Mammalian Mitotic Aurora Kinases: Who's Who?  

NSDL National Science Digital Library

Several serine-threonine kinases related to the Ipl1p kinase in budding yeast, termed aurora kinases, have been cloned recently. Their characterization revealed them to be important regulators of mitotic functions, including (i) the separation of the centrosome, (ii) assembly of the spindles, and (iii) segregation of the chromosomes. The Perspective by Descamps and Prigent delves into the latest observations on aurora kinases in humans and the specific roles of each kinase within the process of mitosis.

Simon Descamps (Universite de Rennes I;Groupe Cycle Cellulaire and Genetique et Developpement REV); Claude Prigent (Universite de Rennes I;Groupe Cycle Cellulaire and Genetique et Developpement REV)

2001-03-13

101

Using high spectral resolution spectrophotometry to study broad mineral absorption features on Mars  

NASA Technical Reports Server (NTRS)

Traditionally telescopic measurements of mineralogic absorption features have been made using relatively low to moderate (R=30-300) spectral resolution. Mineralogic absorption features tend to be broad so high resolution spectroscopy (R greater than 10,000) does not provide significant additional compositional information. Low to moderate resolution spectroscopy allows an observer to obtain data over a wide wavelength range (hundreds to thousands of wavenumbers) compared to the several wavenumber intervals that are collected using high resolution spectrometers. However, spectrophotometry at high resolution has major advantages over lower resolution spectroscopy in situations that are applicable to studies of the Martian surface, i.e., at wavelengths where relatively weak surface absorption features and atmospheric gas absorption features both occur.

Blaney, D. L.; Crisp, D.

1993-01-01

102

Mitotic spindle studied using picosecond laser scissors  

NASA Astrophysics Data System (ADS)

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

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

2006-09-01

103

Hybrid feature detection and information accumulation using high-resolution LC- MS metabolomics data  

PubMed Central

Feature detection is a critical step in the preprocessing of Liquid Chromatography – Mass Spectrometry (LC-MS) metabolomics data. Currently, the predominant approach is to detect features using noise filters and peak shape models based on the data at hand alone. Databases of known metabolites and historical data contain information that could help boost the sensitivity of feature detection, especially for low-concentration metabolites. However, utilizing such information in targeted feature detection may cause large number of false-positives because of the high levels of noise in LC-MS data. With high-resolution mass spectrometry such as Liquid Chromatograph – Fourier Transform Liquid Chromatography (LC-FTMS), high-confidence matching of peaks to known features is feasible. Here we describe a computational approach that serves two purposes. First it boosts feature detection sensitivity by using a hybrid procedure of both untargeted and targeted peak detection. New algorithms are designed to reduce the chance of false-positives by non-parametric local peak detection and filtering. Second, it can accumulate information on the concentration variation of metabolites over large number of samples, which can help find rare features and/or features with uncommon concentration in future studies. Information can be accumulated on features that are consistently found in real data even before their identities are found. We demonstrate the value of the approach in a proof-of-concept study. The method is implemented as part of the R package apLCMS at http://www.sph.emory.edu/apLCMS/.

Yu, Tianwei; Park, Youngja; Li, Shuzhao; Jones, Dean P.

2013-01-01

104

Hybrid feature detection and information accumulation using high-resolution LC-MS metabolomics data.  

PubMed

Feature detection is a critical step in the preprocessing of liquid chromatography-mass spectrometry (LC-MS) metabolomics data. Currently, the predominant approach is to detect features using noise filters and peak shape models based on the data at hand alone. Databases of known metabolites and historical data contain information that could help boost the sensitivity of feature detection, especially for low-concentration metabolites. However, utilizing such information in targeted feature detection may cause large number of false positives because of the high levels of noise in LC-MS data. With high-resolution mass spectrometry such as liquid chromatograph-Fourier transform mass spectrometry (LC-FTMS), high-confidence matching of peaks to known features is feasible. Here we describe a computational approach that serves two purposes. First it boosts feature detection sensitivity by using a hybrid procedure of both untargeted and targeted peak detection. New algorithms are designed to reduce the chance of false-positives by nonparametric local peak detection and filtering. Second, it can accumulate information on the concentration variation of metabolites over large number of samples, which can help find rare features and/or features with uncommon concentration in future studies. Information can be accumulated on features that are consistently found in real data even before their identities are found. We demonstrate the value of the approach in a proof-of-concept study. The method is implemented as part of the R package apLCMS at http://www.sph.emory.edu/apLCMS/ . PMID:23362826

Yu, Tianwei; Park, Youngja; Li, Shuzhao; Jones, Dean P

2013-03-01

105

Local-Learning-Based Feature Selection for High-Dimensional Data Analysis  

PubMed Central

This paper considers feature selection for data classification in the presence of a huge number of irrelevant features. We propose a new feature-selection algorithm that addresses several major issues with prior work, including problems with algorithm implementation, computational complexity, and solution accuracy. The key idea is to decompose an arbitrarily complex nonlinear problem into a set of locally linear ones through local learning, and then learn feature relevance globally within the large margin framework. The proposed algorithm is based on well-established machine learning and numerical analysis techniques, without making any assumptions about the underlying data distribution. It is capable of processing many thousands of features within minutes on a personal computer while maintaining a very high accuracy that is nearly insensitive to a growing number of irrelevant features. Theoretical analyses of the algorithm’s sample complexity suggest that the algorithm has a logarithmical sample complexity with respect to the number of features. Experiments on 11 synthetic and real-world data sets demonstrate the viability of our formulation of the feature-selection problem for supervised learning and the effectiveness of our algorithm.

Sun, Yijun; Todorovic, Sinisa; Goodison, Steve

2012-01-01

106

Effect of Cell Shape and Dimensionality on Spindle Orientation and Mitotic Timing  

PubMed Central

The formation and orientation of the mitotic spindle is a critical feature of mitosis. The morphology of the cell and the spatial distribution and composition of the cells' adhesive microenvironment all contribute to dictate the position of the spindle. However, the impact of the dimensionality of the cells' microenvironment has rarely been studied. In this study we present the use of a microwell platform, where the internal surfaces of the individual wells are coated with fibronectin, enabling the three-dimensional presentation of adhesive ligands to single cells cultured within the microwells. This platform was used to assess the effect of dimensionality and cell shape in a controlled microenvironment. Single HeLa cells cultured in circular microwells exhibited greater tilting of the mitotic spindle, in comparison to cells cultured in square microwells. This correlated with an increase in the time required to align the chromosomes at the metaphase plate due to prolonged activation of the spindle checkpoint in an actin dependent process. The comparison to 2D square patterns revealed that the dimensionality of cell adhesions alone affected both mitotic timings and spindle orientation; in particular the role of actin varied according to the dimensionality of the cells' microenvironment. Together, our data revealed that cell shape and the dimensionality of the cells' adhesive environment impacted on both the orientation of the mitotic spindle and progression through mitosis.

Charnley, Mirren; Anderegg, Fabian; Holtackers, Rene; Textor, Marcus; Meraldi, Patrick

2013-01-01

107

G1/S CDK is inhibited to restrain mitotic onset when DNA replication is blocked in fission yeast  

PubMed Central

Cyclin-dependent kinase (CDK) Tyr15 phosphorylation plays a major role in regulating G2/M CDKs, but the role of this phosphorylation in regulating G1/S CDKs is less clear. We have studied the regulation and function of Cdc2-Tyr15 phosphorylation in the fission yeast Schizosaccharomyces pombe G1/S CDK Cig2/Cdc2. This complex is subject to high level Cdc2-Tyr15 phosphorylation inhibiting its kinase activity in hydroxyurea-treated cells blocked in S-phase. We show that this Tyr15 phosphorylation is required to maintain efficient mitotic checkpoint arrest, because Cig2 accumulates during the block and this accumulation can advance mitotic onset. This mitotic induction operates, at least in part, through activation of the normal G2/M CDK complex Cdc13/Cdc2. Thus, Tyr15 phosphorylation of G1/S CDK complexes is important in the checkpoint control blocking mitotic onset when DNA replication is inhibited.

Zarzov, Patrick; Decottignies, Anabelle; Baldacci, Giuseppe; Nurse, Paul

2002-01-01

108

Amphiastral mitotic spindle assembly in vertebrate cells lacking centrosomes.  

PubMed

The role of centrosomes and centrioles during mitotic spindle assembly in vertebrates remains controversial. In cell-free extracts and experimentally derived acentrosomal cells, randomly oriented microtubules (MTs) self-organize around mitotic chromosomes and assemble anastral spindles. However, vertebrate somatic cells normally assemble a connected pair of polarized, astral MT arrays--termed an amphiaster ("a star on both sides")--that is formed by the splitting and separation of the microtubule-organizing center (MTOC) well before nuclear envelope breakdown (NEB). Whether amphiaster formation requires splitting of duplicated centrosomes is not known. We found that when centrosomes were removed from living vertebrate cells early in their cell cycle, an acentriolar MTOC reassembled, and, prior to NEB, a functional amphiastral spindle formed. Cytoplasmic dynein, dynactin, and pericentrin are all recruited to the interphase aMTOC, and the activity of kinesin-5 is needed for amphiaster formation. Mitosis proceeded on time and these karyoplasts divided in two. However, ~35% of aMTOCs failed to split and separate before NEB, and these entered mitosis with persistent monastral spindles. Chromatin-associated RAN-GTP--the small GTPase Ran in its GTP bound state--could not restore bipolarity to monastral spindles, and these cells exited mitosis as single daughters. Our data reveal the novel finding that MTOC separation and amphiaster formation does not absolutely require the centrosome, but, in its absence, the fidelity of bipolar spindle assembly is highly compromised. PMID:21439826

Hornick, Jessica E; Mader, Christopher C; Tribble, Emily K; Bagne, Cydney C; Vaughan, Kevin T; Shaw, Sidney L; Hinchcliffe, Edward H

2011-04-12

109

Differential Mitotic Stability of Yeast Disomes Derived from Triploid Meiosis  

PubMed Central

The frequencies of recovered disomy among the meiotic segregants of yeast (Saccharomyces cerevisiae) triploids were assessed under conditions in which all 17 yeast chromosomes were monitored simultaneously. The studies employed inbred triploids, in which all homologous centromeres were identical by descent, and single haploid testers carrying genetic markers for all 17 linkage groups. The principal results include: (1) Ascospores from triploid meiosis germinate at frequencies comparable to those from normal diploids, but most fail to produce visible colonies due to the growth-retarding effects of high multiple disomy. (2) The probability of disome formation during triploid meiosis is the same for all chromosomes; disomy for any given chromosome does not exclude simultaneous disomy for any other chromosome. (3) The 17 yeast chromosomes fall into three frequency classes in terms of disome recovery. The results support the idea that multiply disomic meiotic segregants of the triploid experience repeated, nonrandom, post-germination mitotic chromosome losses (N+1?N) and that the observed variations in individual disome recovery are wholly attributable to inherent differences in disome mitotic stability.

Campbell, Douglas; Doctor, John S.; Feuersanger, Jeane H.; Doolittle, Mark M.

1981-01-01

110

Revertant somatic mosaicism by mitotic recombination in dyskeratosis congenita.  

PubMed

Revertant mosaicism is an infrequently observed phenomenon caused by spontaneous correction of a pathogenic allele. We have observed such reversions caused by mitotic recombination of mutant TERC (telomerase RNA component) alleles in six patients from four families affected by dyskeratosis congenita (DC). DC is a multisystem disorder characterized by mucocutaneous abnormalities, dystrophic nails, bone-marrow failure, lung fibrosis, liver cirrhosis, and cancer. We identified a 4 nt deletion in TERC in a family with an autosomal-dominant form of DC. In two affected brothers without bone-marrow failure, sequence analysis revealed pronounced overrepresentation of the wild-type allele in blood cells, whereas no such skewing was observed in the other tissues tested. These observations suggest that this mosaic pattern might have resulted from somatic reversion of the mutated allele to the normal allele in blood-forming cells. SNP-microarray analysis on blood DNA from the two brothers indeed showed independent events of acquired segmental isodisomy of chromosome 3q, including TERC, indicating that the reversions must have resulted from mitotic recombination events. Subsequently, after developing a highly sensitive method of detecting mosaic homozygosity, we have found four additional cases with a mosaic-reversion pattern in blood cells; these four cases are part of a cohort of 17 individuals with germline TERC mutations. This shows that revertant mosaicism is a recurrent event in DC. This finding has important implications for improving diagnostic testing and understanding the variable phenotype of DC. PMID:22341970

Jongmans, Marjolijn C J; Verwiel, Eugene T P; Heijdra, Yvonne; Vulliamy, Tom; Kamping, Eveline J; Hehir-Kwa, Jayne Y; Bongers, Ernie M H F; Pfundt, Rolph; van Emst, Liesbeth; van Leeuwen, Frank N; van Gassen, Koen L I; Geurts van Kessel, Ad; Dokal, Inderjeet; Hoogerbrugge, Nicoline; Ligtenberg, Marjolijn J L; Kuiper, Roland P

2012-03-01

111

Microtubule-dependent regulation of mitotic protein degradation.  

PubMed

Accurate cell division depends on tightly regulated ubiquitylation events catalyzed by the anaphase-promoting complex (APC/C). Among its many substrates, the APC/C triggers the degradation of proteins that stabilize the mitotic spindle, and loss or accumulation of such spindle assembly factors can result in aneuploidy and cancer. Although critical for cell division, it has remained poorly understood how the timing of spindle assembly factor degradation is established during mitosis. Here, we report that active spindle assembly factors are protected from APC/C-dependent degradation by microtubules. In contrast, those molecules that are not bound to microtubules are highly susceptible to proteolysis and turned over immediately after APC/C activation. The correct timing of spindle assembly factor degradation, as achieved by this regulatory circuit, is required for accurate spindle structure and function. We propose that the localized stabilization of APC/C substrates provides a mechanism for the selective disposal of cell-cycle regulators that have fulfilled their mitotic roles. PMID:24462202

Song, Ling; Craney, Allison; Rape, Michael

2014-01-23

112

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

PubMed

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

Halappanavar, Sabina S; Shah, Girish M

2004-03-01

113

Incremental Slow Feature Analysis: Adaptive Low-Complexity Slow Feature Updating from High-Dimensional Input Streams  

Microsoft Academic Search

We introduce here an incremental version of slow feature analysis (IncSFA), combining candid covariance-free incremental principal components analysis (CCIPCA) and covariance-free incremental minor components analysis (CIMCA). IncSFA's feature updating complexity is linear with respect to the input dimensionality, while batch SFA's (BSFA) updating complexity is cubic. IncSFA does not need to store, or even compute, any covariance matrices. The drawback

Varun Raj Kompella; Matthew Luciw; Jürgen Schmidhuber

2012-01-01

114

Mitotic Phosphorylation of Histone H3: Spatio-Temporal Regulation by Mammalian Aurora Kinases  

Microsoft Academic Search

Phosphorylation at a highly conserved serine residue (Ser-10) in the histone H3 tail is considered to be a crucial event for the onset of mitosis. This modification appears early in the G2 phase within pericentromeric heterochromatin and spreads in an ordered fashion coincident with mitotic chromosome condensation. Mu- tation of Ser-10 is essential in Tetrahymena, since it results in abnormal

Claudia Crosio; Gian Maria Fimia; Romain Loury; Masashi Kimura; Yukio Okano; Hongyi Zhou; Subrata Sen; C. David Allis; Paolo Sassone-Corsi

2002-01-01

115

A High Precision Feature Based on LBP and Gabor Theory for Face Recognition  

PubMed Central

How to describe an image accurately with the most useful information but at the same time the least useless information is a basic problem in the recognition field. In this paper, a novel and high precision feature called BG2D2LRP is proposed, accompanied with a corresponding face recognition system. The feature contains both static texture differences and dynamic contour trends. It is based on Gabor and LBP theory, operated by various kinds of transformations such as block, second derivative, direct orientation, layer and finally fusion in a particular way. Seven well-known face databases such as FRGC, AR, FERET and so on are used to evaluate the veracity and robustness of the proposed feature. A maximum improvement of 29.41% is achieved comparing with other methods. Besides, the ROC curve provides a satisfactory figure. Those experimental results strongly demonstrate the feasibility and superiority of the new feature and method.

Xia, Wei; Yin, Shouyi; Ouyang, Peng

2013-01-01

116

Mitotic activity within dermal melanocytes of benign melanocytic nevi: a study of 100 cases with clinical follow-up.  

PubMed

It is generally accepted that otherwise benign intradermal or compound melanocytic nevi may show mitotic activity within dermal melanocytes. However, it is not known whether there is any clinical significance to this finding. Our objective is to analyze and describe the clinicopathologic features of benign nevi with mitotic activity (NMA). To do this, we collected 100 consecutive NMA during the usual course of business in our private dermatopathology practice. These cases were seen between the years 2000 and 2008. We then collected clinical and pathologic data on these cases and compared the findings with 100 control nevi without mitotic activity (CN). We compared these nevi with regard to demographic features, clinical history provided by clinician, and clinical follow-up, as well as anatomic site and season of biopsy, type of nevus, and selected histologic features (ie, trauma). We also estimate the incidence of NMA and describe the amount and location of mitotic figures within the NMA. Our results indicate that the incidence of NMA is 0.91%. Most (80) NMA revealed only one mitotic figure, whereas some (20) NMA revealed more than one mitotic figure. Most NMA (89) showed mitotic activity in the upper portion of the nevus, whereas some (11) showed mitotic activity in the lower portion of the nevus. NMA patients were of younger age than the CN patients (P = 0.0019). Compared with CN, the NMA were more likely to be from the extremities (P = 0.0113) or head and neck (P = 0.0237) and less likely to be from the trunk (P < 0.001). The NMA were also more likely to show histologic features suggesting a congenital onset (P < 0.001) and were more likely to be Spitz nevi (P = 0.0185). Compared with the CN, the NMA were more often reexcised (P = 0.0073) and more often, there was residual nevus in the reexcision specimen (P = 0.13), although the latter finding was not statistically significant. Anecdotally, 2 of our NMA were identified adjacent to invasive melanomas; however, on clinical follow-up, we were unable to detect any increased incidence of melanoma. PMID:21358381

Ruhoy, Steven M; Kolker, Steven E; Murry, Todd C

2011-04-01

117

MELK is an oncogenic kinase essential for mitotic progression in basal-like breast cancer cells  

PubMed Central

Despite marked advances in breast cancer therapy, basal-like breast cancer (BBC), an aggressive subtype of breast cancer usually lacking estrogen and progesterone receptors, remains difficult to treat. In this study, we report the identification of MELK as a novel oncogenic kinase from an in vivo tumorigenesis screen using a kinome-wide open reading frames (ORFs) library. Analysis of clinical data reveals a high level of MELK overexpression in BBC, a feature that is largely dependent on FoxM1, a master mitotic transcription factor that is also found to be highly overexpressed in BBC. Ablation of MELK selectively impairs proliferation of basal-like, but not luminal breast cancer cells both in vitro and in vivo. Mechanistically, depletion of MELK in BBC cells induces caspase-dependent cell death, preceded by defective mitosis. Finally, we find that Melk is not required for mouse development and physiology. Together, these data indicate that MELK is a normally non-essential kinase, but is critical for BBC and thus represents a promising selective therapeutic target for the most aggressive subtype of breast cancer. DOI: http://dx.doi.org/10.7554/eLife.01763.001

Wang, Yubao; Lee, Young-Mi; Baitsch, Lukas; Huang, Alan; Xiang, Yi; Tong, Haoxuan; Lako, Ana; Von, Thanh; Choi, Christine; Lim, Elgene; Min, Junxia; Li, Li; Stegmeier, Frank; Schlegel, Robert; Eck, Michael J; Gray, Nathanael S; Mitchison, Timothy J; Zhao, Jean J

2014-01-01

118

Performance analysis of MSP: a feature-rich high-speed transport protocol  

Microsoft Academic Search

The performance of the multistream protocol (MSP), a feature-rich flexible transport designed to meet the needs of high-performance applications, is analyzed. The analysis is based on the processing complexity associated with performing certain protocol functions and it highlights the advantages and disadvantages of the implementation of several different protocol mechanisms, such as packet or block mode data transfer. The analysis

Thomas F. La Porta; Mischa Schwartz

1993-01-01

119

Dynamics and inherent safety features of small modular high temperature gas-cooled reactors  

Microsoft Academic Search

Investigations were made at Oak Ridge National Laboratory to characterize the dynamics and inherent safety features of various modular high temperature gas-cooled reactor (HTGR) designs. This work was sponsored by the US Nuclear Regulatory Commission's HTGR Safety Research program. The US Department of Energy (DOE) and the Gas Cooled Reactor Associates (GCRA) have sponsored studies of several modular HTGR concepts,

R. M. Harrington; S. J. Ball; J. C. Cleveland

1986-01-01

120

The Mitotic Spindle: A Self-Made Machine  

NSDL National Science Digital Library

The mitotic spindle is a highly dynamic molecular machine composed of tubulin, motors, and other molecules. It assembles around the chromosomes and distributes the duplicated genome to the daughter cells during mitosis. The biochemical and physical principles that govern the assembly of this machine are still unclear. However, accumulated discoveries indicate that chromosomes play a key role. Apparently, they generate a local cytoplasmic state that supports the nucleation and growth of microtubules. Then soluble and chromosome-associated molecular motors sort them into a bipolar array. The emerging picture is that spindle assembly is governed by a combination of modular principles and that their relative contribution may vary in different cell types and in various organisms.

E. Karsenti (EMBL;Cell Biology and Biophysics Program); I. Vernos (EMBL;Cell Biology and Biophysics Program)

2001-10-19

121

Inhibition of Cdc42 during mitotic exit is required for cytokinesis  

PubMed Central

The role of Cdc42 and its regulation during cytokinesis is not well understood. Using biochemical and imaging approaches in budding yeast, we demonstrate that Cdc42 activation peaks during the G1/S transition and during anaphase but drops during mitotic exit and cytokinesis. Cdc5/Polo kinase is an important upstream cell cycle regulator that suppresses Cdc42 activity. Failure to down-regulate Cdc42 during mitotic exit impairs the normal localization of key cytokinesis regulators—Iqg1 and Inn1—at the division site, and results in an abnormal septum. The effects of Cdc42 hyperactivation are largely mediated by the Cdc42 effector p21-activated kinase Ste20. Inhibition of Cdc42 and related Rho guanosine triphosphatases may be a general feature of cytokinesis in eukaryotes.

Atkins, Benjamin D.; Yoshida, Satoshi; Saito, Koji; Wu, Chi-Fang; Lew, Daniel J.

2013-01-01

122

Correlation between high-resolution computed tomography features and patients' characteristics in chronic obstructive pulmonary disease  

PubMed Central

BACKGROUND: During the last few decades, high-resolution computed tomography (HRCT) has come up as a new diagnostic modality to diagnose emphysematous and chronic bronchitis components of chronic obstructive pulmonary disease (COPD). The present study was undertaken to evaluate for various quantitative and qualitative HRCT features in patients with COPD, and to detect patients' characteristics that correlate with these HRCT features. MATERIALS AND METHODS: Forty male patients with COPD attending the COPD clinic at a tertiary referral hospital and postgraduate medical institute were included in the study. Various HRCT features, including tracheal index, thoracic cage ratio, sterno-aortic distance, thoracic cross-sectional area, vascular attenuation, vascular distortion, mosaic attenuation pattern, and directly visible small airways, were evaluated and correlated with patients' characteristics, including age, duration of illness, quantum of smoking, dyspnea score, quality-of-life index, and various spirometric indices. RESULTS: We found significant correlations of various quantitative and qualitative HRCT features with age, duration of illness, quantum of smoking, quality-of-life index, and the spirometric indices showing the extent of airways obstruction. CONCLUSIONS: Various quantitative and qualitative HRCT features were found to correlate with patients' characteristics, spirometric indices, and health-related quality-of-life score, suggesting that HRCT is useful not only in detecting emphysema and its various subtypes but also in predicting the extent and severity of COPD.

Gupta, Prem P.; Yadav, Rohtash; Verma, Manish; Agarwal, Dipti; Kumar, Manoj

2008-01-01

123

A PLANETARY LENSING FEATURE IN CAUSTIC-CROSSING HIGH-MAGNIFICATION MICROLENSING EVENTS  

SciTech Connect

Current microlensing follow-up observations focus on high-magnification events because of the high efficiency of planet detection. However, central perturbations of high-magnification events caused by a planet can also be produced by a very close or a very wide binary companion, and the two kinds of central perturbations are not generally distinguished without time consuming detailed modeling (a planet-binary degeneracy). Hence, it is important to resolve the planet-binary degeneracy that occurs in high-magnification events. In this paper, we investigate caustic-crossing high-magnification events caused by a planet and a wide binary companion. From this investigation, we find that because of the different magnification excess patterns inside the central caustics induced by the planet and the binary companion, the light curves of the caustic-crossing planetary-lensing events exhibit a feature that is discriminated from those of the caustic-crossing binary-lensing events, and the feature can be used to immediately distinguish between the planetary and binary companions. The planetary-lensing feature appears in the interpeak region between the two peaks of the caustic-crossings. The structure of the interpeak region for the planetary-lensing events is smooth and convex or boxy, whereas the structure for the binary-lensing events is smooth and concave. We also investigate the effect of a finite background source star on the planetary-lensing feature in the caustic-crossing high-magnification events. From this, we find that the convex-shaped interpeak structure appears in a certain range that changes with the mass ratio of the planet to the planet-hosting star.

Chung, Sun-Ju; Hwang, Kyu-Ha; Ryu, Yoon-Hyun; Lee, Chung-Uk, E-mail: sjchung@kasi.re.kr, E-mail: kyuha@kasi.re.kr, E-mail: yhryu@kasi.re.kr, E-mail: leecu@kasi.re.kr [Korea Astronomy and Space Science Institute, Hwaam-Dong, Yuseong-Gu, Daejeon 305-348 (Korea, Republic of)

2012-05-20

124

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

SciTech Connect

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.

Salmela, Anna-Leena [VTT Technical Research Centre of Finland, Medical Biotechnology, P.O. Box 106, Turku (Finland) [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)] [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)] [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)] [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) [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)] [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) [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

125

Centromere fragmentation is a common mitotic defect of S and G2 checkpoint override  

PubMed Central

DNA damaging agents, including those used in the clinic, activate cell cycle checkpoints, which blocks entry into mitosis. Given that checkpoint override results in cell death via mitotic catastrophe, inhibitors of the DNA damage checkpoint are actively being pursued as chemosensitization agents. Here we explored the effects of gemcitabine in combination with Chk1 inhibitors in a panel of pancreatic cancer cell lines and found variable abilities to override the S phase checkpoint. In cells that were able to enter mitosis, the chromatin was extensively fragmented, as assessed by metaphase spreads and Comet assay. Notably, electron microscopy and high-resolution light microscopy showed that the kinetochores and centromeres appeared to be detached from the chromatin mass, in a manner reminiscent of mitosis with unreplicated genomes (MUGs). Cell lines that were unable to override the S phase checkpoint were able to override a G2 arrest induced by the alkylator MMS or the topoisomerase II inhibitors doxorubicin or etoposide. Interestingly, checkpoint override from the topoisomerase II inhibitors generated fragmented kinetochores (MUGs) due to unreplicated centromeres. Our studies show that kinetochore and centromere fragmentation is a defining feature of checkpoint override and suggests that loss of cell viability is due in part to acentric genomes. Furthermore, given the greater efficacy of forcing cells into premature mitosis from topoisomerase II-mediated arrest as compared with gemcitabine-mediated arrest, topoisomerase II inhibitors maybe more suitable when used in combination with checkpoint inhibitors.

Beeharry, Neil; Rattner, Jerome B.; Caviston, Juliane P.; Yen, Tim

2013-01-01

126

Inherited X-chromosome inverted tandem duplication in a male traced to a grandparental mitotic error.  

PubMed Central

A male infant was referred for cytogenetic evaluation because of dysmorphic features and developmental delay. In both lymphocytes and skin fibroblasts, a modal number of 46 chromosomes was obtained with an obvious elongation of the long arm of the X chromosome (Xq+). Studies of seven members in 3 generations of this family showed that the proband's mother, sister, and maternal grandmother were phenotypically normal carriers of this abnormal X chromosome. High resolution GTG- and RBG-banding defined the extra chromatin material as an inverted duplication of Xq21----Xq24. This was supported by an approximate twofold increase in alpha-galactosidase A activity, localized to Xq21----q24, observed in the proband's lymphocytes and fibroblasts. BrdU-incorporation studies of the mother's lymphocytes showed the abnormal X to be late replicating in all 100 cells studied and normal alpha-galactosidase A levels. Cytogenetic analysis of the maternal grandmother revealed cytogenetic mosaicism with one cell line containing the abnormal X (37%), and the other, a normal female karyotype (63%). This family is instructive since: (1) it represents only the second case of a dysmorphic male demonstrating a confirmed interstitial partial Xq duplication, and (2) the origin of this familial structural rearrangement has been traced to a grandparental mitotic error. Images Fig. 1 Fig. 2

Schwartz, S; Schwartz, M F; Panny, S R; Peterson, C J; Waters, E; Cohen, M M

1986-01-01

127

An improved retinal vessel segmentation method based on high level features for pathological images.  

PubMed

Most of the retinal blood vessel segmentation approaches use low level features, resulting in segmenting non-vessel structures together with vessel structures in pathological retinal images. In this paper, a new segmentation method based on high level features is proposed which can process the structure of vessel and non-vessel independently. In this method, segmentation is done in two steps. First, using low level features segmentation is accomplished. Second, using high level features, the non-vessel components are removed. For evaluation, STARE database is used which is publicly available in this field. The results show that the proposed method has 0.9536 accuracy and 0.0191 false positive average on all images of the database and 0.9542 accuracy and 0.0236 false positive average on pathological images. Therefore, the proposed approach shows acceptable accuracy on all images compared to other state of the art methods, and the least false positive average on pathological images. PMID:25037714

Ganjee, Razieh; Azmi, Reza; Gholizadeh, Behrouz

2014-09-01

128

Force and Length in the Mitotic Spindle  

PubMed Central

The mitotic spindle assembles to a steady-state length at metaphase through the integrated action of molecular mechanisms that generate and respond to mechanical forces. While molecular mechanisms that produce force have been described, our understanding of how they integrate with each other, and with the assembly-disassembly mechanisms that regulate length, is poor. We review current understanding of the basic architecture and dynamics of the metaphase spindle, and some of the elementary force producing mechanisms. We then discuss models for force integration, and spindle length determination. We also emphasize key missing data that notably includes absolute values of forces, and how they vary as a function of position, within the spindle.

Dumont, Sophie; Mitchison, Timothy J.

2009-01-01

129

Mitotic checkpoint control and chromatin remodeling.  

PubMed

In order to maintain chromosomal stability during cell division, eukaryotic cells have evolved a number of surveillance mechanisms termed checkpoints. These checkpoints monitor the completion of essential molecular and cellular processes of one stage before entering another. The spindle checkpoint watches the bi-orientation attachment of spindle microtubules to all condensed chromosomes before initiation of nuclear division during mitosis. Histones are subject to a number of post-translational modifications during the cell cycle, which may in turn modify or facilitate cell cycle progression. Recent studies suggest that mitotic proteins including Bub1 and Sgo1 that are involved in the spindle checkpoint also play a major role in the regulation of histone modifications and chromatin remodeling. This mini-review summarizes emerging information about the new role of spindle checkpoint proteins in chromatin remodeling. PMID:22201785

Yao, Yixin; Dai, Wei

2012-01-01

130

NAD(P)H:Quinone Oxidoreductase 1 (NQO1) Localizes to the Mitotic Spindle in Human Cells  

PubMed Central

NAD(P)H:quinone oxidoreductase 1 (NQO1) is an FAD containing quinone reductase that catalyzes the 2-electron reduction of a broad range of quinones. The 2-electron reduction of quinones to hydroquinones by NQO1 is believed to be a detoxification process since this reaction bypasses the formation of the highly reactive semiquinone. NQO1 is expressed at high levels in normal epithelium, endothelium and adipocytes as well as in many human solid tumors. In addition to its function as a quinone reductase NQO1 has been shown to reduce superoxide and regulate the 20 S proteasomal degradation of proteins including p53. Biochemical studies have indicated that NQO1 is primarily located in the cytosol, however, lower levels of NQO1 have also been found in the nucleus. In these studies we demonstrate using immunocytochemistry and confocal imaging that NQO1 was found associated with mitotic spindles in cells undergoing division. The association of NQO1 with the mitotic spindles was observed in many different human cell lines including nontransformed cells (astrocytes, HUVEC) immortalized cell lines (HBMEC, 16HBE) and cancer (pancreatic adenocarcinoma, BXPC3). Confocal analysis of double-labeling experiments demonstrated co-localization of NQO1with alpha-tubulin in mitotic spindles. In studies with BxPc-3 human pancreatic cancer cells the association of NQO1 with mitotic spindles appeared to be unchanged in the presence of NQO1 inhibitors ES936 or dicoumarol suggesting that NQO1 can associate with the mitotic spindle and still retain catalytic activity. Analysis of archival human squamous lung carcinoma tissue immunostained for NQO1 demonstrated positive staining for NQO1 in the spindles of mitotic cells. The purpose of this study is to demonstrate for the first time the association of the quinone reductase NQO1 with the mitotic spindle in human cells.

Siegel, David; Kepa, Jadwiga K.; Ross, David

2012-01-01

131

Recombinogenic Conditions Influence Partner Choice in Spontaneous Mitotic Recombination  

PubMed Central

Mammalian common fragile sites are loci of frequent chromosome breakage and putative recombination hotspots. Here, we utilized Replication Slow Zones (RSZs), a budding yeast homolog of the mammalian common fragile sites, to examine recombination activities at these loci. We found that rates of URA3 inactivation of a hisG-URA3-hisG reporter at RSZ and non-RSZ loci were comparable under all conditions tested, including those that specifically promote chromosome breakage at RSZs (hydroxyurea [HU], mec1? sml1?, and high temperature), and those that suppress it (sml1? and rrm3?). These observations indicate that RSZs are not recombination hotspots and that chromosome fragility and recombination activity can be uncoupled. Results confirmed recombinogenic effects of HU, mec1? sml1?, and rrm3? and identified temperature as a regulator of mitotic recombination. We also found that these conditions altered the nature of recombination outcomes, leading to a significant increase in the frequency of URA3 inactivation via loss of heterozygosity (LOH), the type of genetic alteration involved in cancer development. Further analyses revealed that the increase was likely due to down regulation of intrachromatid and intersister (IC/IS) bias in mitotic recombination, and that RSZs exhibited greater sensitivity to HU dependent loss of IC/IS bias than non RSZ loci. These observations suggest that recombinogenic conditions contribute to genome rearrangements not only by increasing the overall recombination activity, but also by altering the nature of recombination outcomes by their effects on recombination partner choice. Similarly, fragile sites may contribute to cancer more frequently than non-fragile loci due their enhanced sensitivity to certain conditions that down-regulate the IC/IS bias rather than intrinsically higher rates of recombination.

Cauwood, James D.; Johnson, Anthony L.; Widger, Alexander; Cha, Rita S.

2013-01-01

132

Moving target feature extraction for airborne high-range resolution phased-array radar  

Microsoft Academic Search

We study the feature extraction of moving targets in the presence of temporally and spatially correlated ground clutter for airborne high-range resolution (HRR) phased-array radar. To avoid the range migration problems that occur in HRR radar data, we first divide the HRR range profiles into low-range resolution (LRR) segments. Since each LRR segment contains a sequence of HRR range bins,

Jian Li; Guoqing Liu; Nanzhi Jiang; Petre Stoica

2001-01-01

133

The Effect of High vs Low Density Barium Preparations on the Quantitative Features of Swallowing  

Microsoft Academic Search

We compared the effect of high-density and low-density barium preparations on the quantitative features of swallowing. The two barium preparations differed primarily in density but also differed somewhat in viscosity. Concurrent videofluoroscopic and manometric studies were done in nine healthy control subjects. Videofluoroscopy was recorded in the lateral projection at 30 frames\\/sec while concurrent manometry was done with five intraluminal

Wylie J. Dodds; Benson T. Massey; Mark K. Kern

1989-01-01

134

New features in Saturn's atmosphere revealed by high-resolution thermal infrared images  

NASA Technical Reports Server (NTRS)

Observations of the stratospheric IR emission structure on Saturn are presented. The high-spatial-resolution global images show a variety of new features, including a narrow equatorial belt of enhanced emission at 7.8 micron, a prominent symmetrical north polar hotspot at all three wavelengths, and a midlatitude structure which is asymmetrically brightened at the east limb. The results confirm the polar brightening and reversal in position predicted by recent models for seasonal thermal variations of Saturn's stratosphere.

Gezari, D. Y.; Mumma, M. J.; Espenak, F.; Deming, D.; Bjoraker, G.; Woods, L.; Folz, W.

1989-01-01

135

Automatic Genre Classification as a Study of the Viability of High-Level Features for Music Classification  

Microsoft Academic Search

This paper examines the potential of high-level features extracted from symbolic musical representations in re- gards to musical classification. Twenty features are im- plemented and tested by using them to classify 225 MIDI files by genre. This system differs from previous auto- matic genre classification systems, which have focused on low-level features extracted from audio data. Files are classified into

Cory McKay

2004-01-01

136

Arsenic Trioxide Suppresses Paclitaxel-Induced Mitotic Arrest  

PubMed Central

To human health, arsenic exhibits the property of a double-edged sword. Arsenic compounds such as As2O3 is effective for the treatment of relapsed/refractory acute promyelocytic leukemia, whereas chronic exposure to environmental arsenic is associated with the development of a variety of common cancers. Because As2O3 is capable of inhibiting tubulin polymerization and inducing mitotic arrest, we examined whether there existed any functional interaction between As2O3 and paclitaxel, a well-known microtubule poison. Flow cytometry and fluorescence microscopy revealed that although As2O3 alone caused a moderate level of mitotic arrest, it greatly attenuated paclitaxel-induced mitotic arrest in cells with p53 deficiency. Western blot analysis showed that As2O3 significantly blocked phosphorylation of BubR1, Cdc20, and Cdc27 in cells treated with paclitaxel, suggesting that arsenic compromised the activation of the spindle checkpoint. Our further studies revealed that the attenuation of paclitaxel-induced mitotic arrest by As2O3 resulted primarily from sluggish cell cycle progression at S phase but not enhanced mitotic exit. The clinical efficacy of taxol is associated with its ability to induce mitotic arrest and subsequent mitotic catastrophe. Our observations that As2O3 has a negative impact on the cell cycle checkpoint activation by taxol should have significant clinical implications.

Duan, Qing; Komissarova, Elena; Dai, Wei

2014-01-01

137

Determinants of Human Cyclin B1 Association with Mitotic Chromosomes  

PubMed Central

Cyclin B1–CDK1 activity is essential for mitotic entry, but questions remain regarding how the activity of this kinase is spatially regulated. Previous studies showed that the cyclin B1 subunit localizes to several compartments of a mitotic cell, including the centrosomes, mitotic spindle, kinetochores and chromosomes via distinct sequence elements. Mitotic chromosome association occurs through the unstructured N-terminal domain of cyclin B1 and is independent of CDK1 binding. Here, we use live cell imaging of human cyclin B1 fused to GFP to precisely define the sequence elements within cyclin B1 that mediate its association with condensed mitotic chromosomes. We find that a short, evolutionarily conserved N-terminal motif is required for cyclin B1 to localize to mitotic chromosomes. We further reveal a role for arginine residues within and near the destruction box sequence in the chromosome association of cyclin B1. Additionally, our data suggest that sequences further downstream in cyclin B1, such as the cytoplasmic retention sequence and the cyclin box, may negatively modulate chromosome association. Because multiple basic residues are required for cyclin B1 association with mitotic chromosomes, electrostatic interactions with DNA may facilitate cyclin B1 localization to chromosomes.

Pfaff, Kathleen L.; King, Randall W.

2013-01-01

138

Kaposi's Sarcoma-Associated Herpesvirus Latency-Associated Nuclear Antigen Interacts with Bromodomain Protein Brd4 on Host Mitotic Chromosomes  

PubMed Central

The latency-associated nuclear antigen (LANA) of Kaposi's sarcoma-associated herpesvirus (KSHV) is required for viral episome maintenance in host cells during latent infection. Two regions of the protein have been implicated in tethering LANA/viral episomes to the host mitotic chromosomes, and LANA chromosome-binding sites are subjects of high interest. Because previous studies had identified bromodomain protein Brd4 as the mitotic chromosome anchor for the bovine papillomavirus E2 protein, which tethers the viral episomes to host mitotic chromosomes (J. You, J. L. Croyle, A. Nishimura, K. Ozato, and P. M. Howley, Cell 117:349-360, 2004, and J. You, M. R. Schweiger, and P. M. Howley, J. Virol. 79:14956-14961, 2005), we examined whether KSHV LANA interacts with Brd4. We found that LANA binds Brd4 in vivo and in vitro and that the binding is mediated by a direct protein-protein interaction between the ET (extraterminal) domain of Brd4 and a carboxyl-terminal region of LANA previously implicated in chromosome binding. Brd4 associates with mitotic chromosomes throughout mitosis and demonstrates a strong colocalization with LANA and the KSHV episomes on host mitotic chromosomes. Although another bromodomain protein, RING3/Brd2, binds to LANA in a similar fashion in vitro, it is largely excluded from the mitotic chromosomes in KSHV-uninfected cells and is partially recruited to the chromosomes in KSHV-infected cells. These data identify Brd4 as an interacting protein for the carboxyl terminus of LANA on mitotic chromosomes and suggest distinct functional roles for the two bromodomain proteins RING3/Brd2 and Brd4 in LANA binding. Additionally, because Brd4 has recently been shown to have a role in transcription, we examined whether Brd4 can regulate the CDK2 promoter, which can be transactivated by LANA.

You, Jianxin; Srinivasan, Viswanathan; Denis, Gerald V.; Harrington, William J.; Ballestas, Mary E.; Kaye, Kenneth M.; Howley, Peter M.

2006-01-01

139

High-resolution digital elevation models of the Flade Iceblink feature in NE Greenland  

NASA Astrophysics Data System (ADS)

We produce a time series of high-resolution digital elevation models (DEM) to examine the recent evolution of an 8.7 km2 sub-glacial lake collapse feature near the southern summit of the 8500 km2 Flade Isblink Ice Cap (FIIC) in northeastern Greenland [Figure 1]. Visible imagery from the MODerate-resolution Imaging Spectroradiometer (MODIS) indicates the collapse occurred between August 16th and September 6th, 2011 at the site of a recurring moulin. DEMs are extracted using the NASA Ames Stereo Pipeline for the period between June 2012 and late 2013 from 0.5 m resolution along-track stereo image pairs available via the NGA commercial imagery program. The DEMs are compared to a 1996 ERS InSAR derived DEM [Palmer et al., 2010], and to a contemporary airborne laser altimeter swath flown by NASA Icebridge in mid-April 2013 to derive the volume of the feature and the uncertainties on the high-resolution DEMs. The 'mitten' shaped feature is bounded by crevasses on three sides, with a shallow ramp to the south. It is ~70 m deep, 3.7 km north-to-south and 3 km east-to-west and has a volume of ~0.3 km3. Ice penetrating radar from a nearby Icebridge mission in May 2011, indicates the ice is approximately 550 m thick and that the bed is very flat and smooth about 1 km to the southeast of the feature. The nearby bed topography, local geology and lack of recorded seismicity in the area indicate it is unlikely that the feature is the result of either subglacial volcanic activity or the collapse of a limestone karst feature below the ice cap - the neighboring Princess Elizabeth Alps are composed of 420 Ma Caledonide fold belt gneisses. The presence of recurring supraglacial meltwater streams and drainage into the feature, its rapid formation and its steep sided nature instead suggest that it formed during the rapid drainage of a sub-glacial lake - which is, as far as we are aware, the first recorded instance of such an occurrence in Greenland. Meltwater observed using 250 m resolution MODIS imagery during the extensive melt seasons of both 2010 and 2011 flows northwards into the area of the feature before disappearing - presumably down a Moulin. We use RACMO2 to provide rough estimates of the volumes involved. We monitor the elevation of the floor of the feature to see if the subglacial lake is refilling and provide gross, low-resolution estimates of hydraulic head and drainage path calculations for the region. Flade Iceblink feature from IceBridge. Michael Studdinger/NASA mike.willis@cornell.edu Flade Ice Blink as taken by Michael Studdinger/NASA

Willis, M. J.; Juntunen, T.; Porter, C. C.; Morin, P. J.

2013-12-01

140

Mitotic spindle assembly by two different pathways in vitro  

PubMed Central

We have used Xenopus egg extracts to study spindle morphogenesis in a cell-free system and have identified two pathways of spindle assembly in vitro using methods of fluorescent analogue cytochemistry. When demembranated sperm nuclei are added to egg extracts arrested in a mitotic state, individual nuclei direct the assembly of polarized microtubule arrays, which we term half-spindles; half-spindles then fuse pairwise to form bipolar spindles. In contrast, when sperm nuclei are added to extracts that are induced to enter interphase and arrested in the following mitosis, a single sperm nucleus can direct the assembly of a complete spindle. We find that microtubule arrays in vitro are strongly biased towards chromatin, but this does not depend on specific kinetochore-microtubule interactions. Indeed, although we have identified morphological and probably functional kinetochores in spindles assembled in vitro, kinetochores appear not to play an obligate role in the establishment of stable, bipolar microtubule arrays in either assembly pathway. Features of the two pathways suggest that spindle assembly involves a hierarchy of selective microtubule stabilization, involving both chromatin-microtubule interactions and antiparallel microtubule-microtubule interactions, and that fundamental molecular interactions are probably the same in both pathways. This in vitro reconstitution system should be useful for identifying the molecules regulating the generation of asymmetric microtubule arrays and for understanding spindle morphogenesis in general.

1991-01-01

141

SN 2012fr: A Type Ia Supernova with Extreme High Velocity Features and Stratefied Ejecta  

NASA Astrophysics Data System (ADS)

SN 2012fr was a luminous normal Type Ia supernova in the nearby barred spiral galaxy NGC 1365. We obtained 65 optical spectra of SN 2012fr from nine telescopes spanning four continents over a two month period beginning two days after the date of explosion. SN 2012fr exhibited extremely strong high-velocity features (HVFs) at early epochs, and exhibits the strongest HVFs amongst a sample of 58 nearby SNe Ia. Clean separation of the HVFs and photospheric velocity features (PVFs) was facilitated by the narrowness of the PVFs. This narrow line width also revealed a late velocity plateau in lines of intermediate mass elements, which did not manifest for iron group elements, thereby indicating a layering of burning products in the supernova ejecta.

Childress, Michael; Scalzo, R. A.; Sim, S.; Tucker, B. E.; Yuan, F.; Schmidt, B. P.; Supernova Project, Carnegie; PESSTO; Filippenko Supernova Group

2014-01-01

142

Detection and Mapping of Sedimentary Features on Alluvial Fans Using High-Resolution Overhead Thermal Imaging  

NASA Astrophysics Data System (ADS)

In this study we evaluate the utility of thermal imagery for revealing geomorphic features and evidence of sedimentary processes on the surfaces of alluvial fans. Prior studies of alluvial fans have made extensive use of visible imagery and traditional field-based mapping techniques to identify surface geomorphic features and sedimentary processes. Here we present a comparison of features mapped using thermal images acquired from the ground, a light aircraft (altitude ~5000 ft, resolution ~2 m/pixel) and ASTER satellite imagery (resolution 90 m/pixel), to a preexisting ground-based map of features on an example alluvial fan in Owens Valley, California. Thermal images from a light aircraft were acquired at several times of day to determine how the surface temperatures of the alluvial fan rise and fall throughout a diurnal cycle. We have also acquired thermal images of the same fan from the ground at 5 minute intervals over the course of a full diurnal cycle. ASTER thermal data also covers the Owens Valley, and was used to determine if this technique can be used from orbit at significantly lower resolution (90 m/pixel). In an arid climate with low vegetation cover, the temperature of a surface at any given time of day is a complex function of many parameters, including slope, azimuth, composition, degree of induration, and grain size. By analyzing the temperatures on the surface of an alluvial fan with comparable slopes, azimuth, and composition, we make estimates of the relative particle size or degree of induration. We utilize the fact that several sedimentary processes acting on the surface of alluvial fans sort particles by size. For example, both debris flow and channelized flow processes can form linear features of large and small clasts. Therefore, thermal imagery could be expected to reveal evidence of these processes at the surfaces of alluvial fans in the form of spatial patterns of surface thermal properties. Process-related sedimentary features, such as clast-rich and clast-poor debris flows, debris-flow levees, and the change in particle size at the toe of the fan are all clearly revealed in the aerial thermal images of the Dolomite Fan in Owens Valley, California. The locations of these features in the thermal imagery match the locations of the features as mapped using traditional ground-based field sedimentology techniques by Blair and McPherson (1998). All debris flows that are exposed at the fan surface are evident in the aerial thermal imagery, including those that have been heavily weathered and are difficult to observe in visible aerial or orbital imagery. ASTER satellite thermal image data does not show the same sedimentary features as our aerial thermal images, presumably due to the significantly poorer spatial resolution of the satellite data. Our aerial thermal imagery suggests that higher resolution satellite data from a future satellite experiment could be used to detect sedimentary processes on alluvial fans anywhere on Earth. High resolution thermal imagery from above can be used to provide preliminary reconnaissance of an alluvial fan, suggest what processes have most recently acted on the surface of the fan, and to prioritize sites for detailed study on the ground. Future work will expand our database of alluvial fans and the list of process-related surface features that can be identified with thermal imagery.

Hardgrove, C. J.; Moersch, J. E.; Whisner, S.

2008-12-01

143

Vertical circulation structure,interannual variation features and variation mechanism of western pacific subtropical high  

NASA Astrophysics Data System (ADS)

The paper investigates the vertical circulation structure of the western Pacific subtropical high (STH) and its interannual variation features in relation to East Asian subtropical summer monsoon and external thermal forcing by using the high-resolution and good-quality observations from the 1998 South China Sea Summer Monsoon Experiment (SCSMEX), the NCEP 40-year reanalysis data and relevant SST and the STH parameters. It is found that the vertical circulation structures differ greatly in features between quasi-stationary and transient components of the western Pacific STH. When rainstorms happen in the rainband of East Asian subtropical monsoon on the STH north side, the downdrafts are distinct around the ridge at a related meridian. The sinking at high (low) levels comes from the north (south) side of the STH, thereby revealing that the high is a tie between tropical and extratropical systems. The analyses of this paper suggest that the latent heat release associated with subtropical monsoon precipitation, the offshore SST and East Asian land-sea thermal contrast have a significant effect on the STH interannual anomaly. Our numer-ical experiment shows that the offshore SSTA-caused sensible heating may excite an anomalous anticyclonic circulation on the west side, which affects the intensity (area) and meridional position of the western Pacific STH.

He, Jinhai; Zhou, Bing; Wen, Min; Li, Feng

2001-07-01

144

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

SciTech Connect

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.

Komura, Jun-ichiro, E-mail: junkom@med.tohoku.ac.jp [Department of Cell Biology, Tohoku University Graduate School of Medicine, Sendai 980-8575 (Japan)] [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)] [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)] [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)] [Department of Cell Biology, Tohoku University Graduate School of Medicine, Sendai 980-8575 (Japan)

2012-03-10

145

The bipolar assembly domain of the mitotic motor kinesin-5  

PubMed Central

An outstanding unresolved question is how does the mitotic spindle utilize microtubules and mitotic motors to coordinate accurate chromosome segregation during mitosis? This process depends upon the mitotic motor, kinesin-5, whose unique bipolar architecture, with pairs of motor domains lying at opposite ends of a central rod, allows it to crosslink microtubules within the mitotic spindle and to coordinate their relative sliding during spindle assembly, maintenance and elongation. The structural basis of kinesin-5’s bipolarity is, however, unknown, as protein asymmetry has so far precluded its crystallization. Here we use electron microscopy of single molecules of kinesin-5 and its subfragments, combined with hydrodynamic analysis plus mass spectrometry, circular dichroism and site-directed spin label electron paramagnetic resonance spectroscopy, to show how a staggered antiparallel coiled-coil ‘BASS’ (bipolar assembly) domain directs the assembly of four kinesin-5 polypeptides into bipolar minifilaments.

Acar, Seyda; Carlson, David B.; Budamagunta, Madhu S.; Yarov-Yarovoy, Vladimir; Correia, John J.; Ninonuevo, Milady R.; Jia, Weitao; Tao, Li; Leary, Julie A.; Voss, John C.; Evans, James E.; Scholey, Jonathan M.

2013-01-01

146

BRD4 jump-starts transcription after mitotic silencing  

PubMed Central

The chromatin adapter BRD4 may be crucial for transmitting epigenetic information by acting as a histone acetylation-dependent gene bookmark and accelerating post-mitotic transcriptional reactivation.

2011-01-01

147

Classification of high resolution imagery based on fusion of multiscale texture features  

NASA Astrophysics Data System (ADS)

In high resolution data classification process, combining texture features with spectral bands can effectively improve the classification accuracy. However, the window size which is difficult to choose is regarded as an important factor influencing overall classification accuracy in textural classification and current approaches to image texture analysis only depend on a single moving window which ignores different scale features of various land cover types. In this paper, we propose a new method based on the fusion of multiscale texture features to overcome these problems. The main steps in new method include the classification of fixed window size spectral/textural images from 3×3 to 15×15 and comparison of all the posterior possibility values for every pixel, as a result the biggest probability value is given to the pixel and the pixel belongs to a certain land cover type automatically. The proposed approach is tested on University of Pavia ROSIS data. The results indicate that the new method improve the classification accuracy compared to results of methods based on fixed window size textural classification.

Liu, Jinxiu; Liu, Huiping; Lv, Ying; Xue, Xiaojuan

2014-03-01

148

Fully automatic 2D to 3D conversion with aid of high-level image features  

NASA Astrophysics Data System (ADS)

With the recent advent in 3D display technology, there is an increasing need for conversion of existing 2D content into rendered 3D views. We propose a fully automatic 2D to 3D conversion algorithm that assigns relative depth values to the various objects in a given 2D image/scene and generates two different views (stereo pair) using a Depth Image Based Rendering (DIBR) algorithm for 3D displays. The algorithm described in this paper creates a scene model for each image based on certain low-level features like texture, gradient and pixel location and estimates a pseudo depth map. Since the capture environment is unknown, using low-level features alone creates inaccuracies in the depth map. Using such flawed depth map for 3D rendering will result in various artifacts, causing an unpleasant viewing experience. The proposed algorithm also uses certain high-level image features to overcome these imperfections and generates an enhanced depth map for improved viewing experience. Finally, we show several 3D results generated with our algorithm in the results section.

Appia, Vikram; Batur, Umit

2014-03-01

149

Subcellular redistribution and mitotic inheritance of transition metals in proliferating mouse fibroblast cells  

PubMed Central

Synchrotron x-ray fluorescence microscopy of non-synchronized NIH 3T3 fibroblasts revealed an intriguing redistribution dynamics that defines the inheritance of trace metals during mitosis. At metaphase, the highest density areas of Zn and Cu are localized in two distinct regions adjacent to the metaphase plate. As the sister chromatids are pulled towards the spindle poles during anaphase, Zn and Cu gradually move to the center and partition into the daughter cells to yield a pair of twin pools during cytokinesis. Colocalization analyses demonstrated high spatial correlations between Zn, Cu, and S throughout all mitotic stages, while Fe showed consistently different topographies characterized by high-density spots distributed across the entire cell. Whereas the total amount of Cu remained similar compared to interphase cells, mitotic Zn levels increased almost 3-fold, suggesting a prominent physiological role that lies beyond the requirement of Zn as a cofactor in metalloproteins or messenger in signaling pathways.

McRae, Reagan; Lai, Barry; Fahrni, Christoph J.

2012-01-01

150

Aurora B Regulates MCAK at the Mitotic Centromere  

Microsoft Academic Search

Chromosome orientation and alignment within the mitotic spindle requires the Aurora B protein kinase and the mitotic centromere-associated kinesin (MCAK). Here, we report the regulation of MCAK by Aurora B. Aurora B inhibited MCAK's microtubule depolymerizing activity in vitro, and phospho-mimic (S\\/E) mutants of MCAK inhibited depolymerization in vivo. Expression of either MCAK (S\\/E) or MCAK (S\\/A) mutants increased the

Paul D Andrews; Yulia Ovechkina; Nick Morrice; Michael Wagenbach; Karen Duncan; Linda Wordeman; Jason R Swedlow

2004-01-01

151

High-resolution spectroscopy of the 3 micron emission features in NGC 7027 and IRAS 21282+5050  

NASA Technical Reports Server (NTRS)

High-resolution 3 micron spectra of NGC 7027 and IRAS 21282+5050 are presented. The well-known 3.29 micron emission feature has very similar shapes in the two objects, but a small shift is present between them. The emission features at 3.46 and 3.52 microns recently found in IRAS 21282+5050 are also present in the spectrum of NGC 7027. In addition, there may be two other weak features at 3.55 and 3.58 microns in NGC 7027. These emission features might be related to saturated hydrocarbons. The spectra provide further constraints on the origin of the 'unidentified' emission features.

Nagata, Tetsuya; Tokunaga, Alan T.; Sellgren, K.; Smith, Robert G.; Onaka, Takashi

1988-01-01

152

Integrated siRNA design based on surveying of features associated with high RNAi effectiveness  

PubMed Central

Background Short interfering RNAs have allowed the development of clean and easily regulated methods for disruption of gene expression. However, while these methods continue to grow in popularity, designing effective siRNA experiments can be challenging. The various existing siRNA design guidelines suffer from two problems: they differ considerably from each other, and they produce high levels of false-positive predictions when tested on data of independent origins. Results Using a distinctly large set of siRNA efficacy data assembled from a vast diversity of origins (the siRecords data, containing records of 3,277 siRNA experiments targeting 1,518 genes, derived from 1,417 independent studies), we conducted extensive analyses of all known features that have been implicated in increasing RNAi effectiveness. A number of features having positive impacts on siRNA efficacy were identified. By performing quantitative analyses on cooperative effects among these features, then applying a disjunctive rule merging (DRM) algorithm, we developed a bundle of siRNA design rule sets with the false positive problem well curbed. A comparison with 15 online siRNA design tools indicated that some of the rule sets we developed surpassed all of these design tools commonly used in siRNA design practice in positive predictive values (PPVs). Conclusion The availability of the large and diverse siRNA dataset from siRecords and the approach we describe in this report have allowed the development of highly effective and generally applicable siRNA design rule sets. Together with ever improving RNAi lab techniques, these design rule sets are expected to make siRNAs a more useful tool for molecular genetics, functional genomics, and drug discovery studies.

Gong, Wuming; Ren, Yongliang; Xu, Qiqi; Wang, Yejun; Lin, Dong; Zhou, Haiyan; Li, Tongbin

2006-01-01

153

Stable hZW10 kinetochore residency, mediated by hZwint-1 interaction, is essential for the mitotic checkpoint  

PubMed Central

The mitotic checkpoint is an essential surveillance mechanism that ensures high fidelity chromosome segregation during mitosis. Mitotic checkpoint function depends on numerous kinetochore proteins, including ZW10, ROD, and Zwilch (the ROD–ZW10–Zwilch complex). Through an extensive mutagenesis screen of hZW10, we have mapped the kinetochore localization domain of hZW10 as well as the hZwint-1 interaction domain. We find that hZwint-1–noninteracting mutants still localize to kinetochores. In addition, using fluorescence recovery after photobleaching, we have found that hZW10 residency at metaphase kinetochores is brief (half-time of 13 s). However, during prometaphase or at unattached kinetochores, enhanced green fluorescent protein–hZW10 becomes a stable component of the kinetochore. Moreover, we find that stable hZW10 kinetochore residency at prometaphase kinetochores is dependent on its interaction with hZwint-1, and is essential for mitotic checkpoint arrest.

Famulski, Jakub K.; Vos, Larissa; Sun, Xuejun; Chan, Gordon

2008-01-01

154

Cephalalgiaphobia as a feature of high-frequency migraine: a pilot study  

PubMed Central

Background Cephalalgiaphobia is the fear of having a headache attack during a pain-free period that may induce patients to use analgesic in the absence of pain to prevent headache and to improve their performances. This study aims at assessing if cephalalgiaphobia is related to migraine frequency or medication overuse, and if it is per se a predictor of increase in migraine frequency. Methods This is a pilot prospective cohort study on 126 consecutive migraineurs referred to a tertiary Headache Centre. A headache specialist collected data regarding migraine features, frequency and medications at baseline (T0) and 2 years later (T1). Cephalalgiaphobia was investigated at T0 and T1 through a score determined by a 4 items questionnaire. Results Moderate-high migraine frequency was associated with higher risk of cephalalgiaphobia (p?high-frequency migraine feature and may play a role in chronicization. Therefore, it should be better investigated by clinicians and treated or prevented in order to reduce the risk of disability and the increase in migraine frequency.

2013-01-01

155

High Order Linguistic Features Such as Ambiguity Processing as Relevant Diagnostic Markers for Schizophrenia  

PubMed Central

Due to the deficits of schizophrenic patients regarding the understanding of vague meanings (D. Ketteler and S. Ketteler (2010)) we develop a special test battery called HOLF (high order linguistic function test), which should be able to detect subtle linguistic performance deficits in schizophrenic patients. HOLF was presented to 40 schizophrenic patients and controls, focussing on linguistic features such as ambiguity, synonymy, hypero-/hyponymy, antinomy, and adages. Using the HOLF test battery we found that schizophrenic patients showed significant difficulties in discriminating ambiguities, hypero- and hyponymy, or synonymy compared to healthy controls. Antonyms and adages showed less significant results in comparing both groups. The more difficult a linguistic task was, the more confusion was measured in the schizophrenic group while healthy controls did not show significant problems in processing high order language tasks.

Ketteler, Daniel; Theodoridou, Anastasia; Ketteler, Simon; Jager, Matthias

2012-01-01

156

Physiological and genomic features of highly alkaliphilic hydrogen-utilizing Betaproteobacteria from a continental serpentinizing site.  

PubMed

Serpentinization, or the aqueous alteration of ultramafic rocks, results in challenging environments for life in continental sites due to the combination of extremely high pH, low salinity and lack of obvious electron acceptors and carbon sources. Nevertheless, certain Betaproteobacteria have been frequently observed in such environments. Here we describe physiological and genomic features of three related Betaproteobacterial strains isolated from highly alkaline (pH 11.6) serpentinizing springs at The Cedars, California. All three strains are obligate alkaliphiles with an optimum for growth at pH 11 and are capable of autotrophic growth with hydrogen, calcium carbonate and oxygen. The three strains exhibit differences, however, regarding the utilization of organic carbon and electron acceptors. Their global distribution and physiological, genomic and transcriptomic characteristics indicate that the strains are adapted to the alkaline and calcium-rich environments represented by the terrestrial serpentinizing ecosystems. We propose placing these strains in a new genus 'Serpentinomonas'. PMID:24845058

Suzuki, Shino; Kuenen, J Gijs; Schipper, Kira; van der Velde, Suzanne; Ishii, Shun'ichi; Wu, Angela; Sorokin, Dimitry Y; Tenney, Aaron; Meng, XianYing; Morrill, Penny L; Kamagata, Yoichi; Muyzer, Gerard; Nealson, Kenneth H

2014-01-01

157

Physiological and genomic features of highly alkaliphilic hydrogen-utilizing Betaproteobacteria from a continental serpentinizing site  

PubMed Central

Serpentinization, or the aqueous alteration of ultramafic rocks, results in challenging environments for life in continental sites due to the combination of extremely high pH, low salinity and lack of obvious electron acceptors and carbon sources. Nevertheless, certain Betaproteobacteria have been frequently observed in such environments. Here we describe physiological and genomic features of three related Betaproteobacterial strains isolated from highly alkaline (pH 11.6) serpentinizing springs at The Cedars, California. All three strains are obligate alkaliphiles with an optimum for growth at pH 11 and are capable of autotrophic growth with hydrogen, calcium carbonate and oxygen. The three strains exhibit differences, however, regarding the utilization of organic carbon and electron acceptors. Their global distribution and physiological, genomic and transcriptomic characteristics indicate that the strains are adapted to the alkaline and calcium-rich environments represented by the terrestrial serpentinizing ecosystems. We propose placing these strains in a new genus ‘Serpentinomonas’.

Suzuki, Shino; Kuenen, J. Gijs; Schipper, Kira; van der Velde, Suzanne; Ishii, Shun'ichi; Wu, Angela; Sorokin, Dimitry Y.; Tenney, Aaron; Meng, XianYing; Morrill, Penny L.; Kamagata, Yoichi; Muyzer, Gerard; Nealson, Kenneth H.

2014-01-01

158

Mechanism and regulation of kinesin-5, an essential motor for the mitotic spindle.  

PubMed

Mitotic cell division is the most fundamental task of all living cells. Cells have intricate and tightly regulated machinery to ensure that mitosis occurs with appropriate frequency and high fidelity. A core element of this machinery is the kinesin-5 motor protein, which plays essential roles in spindle formation and maintenance. In this review, we discuss how the structural and mechanical properties of kinesin-5 motors uniquely suit them to their mitotic role. We describe some of the small molecule inhibitors and regulatory proteins that act on kinesin-5, and discuss how these regulators may influence the process of cell division. Finally, we touch on some more recently described functions of kinesin-5 motors in non-dividing cells. Throughout, we highlight a number of open questions that impede our understanding of both this motor's function and the potential utility of kinesin-5 inhibitors. PMID:24125467

Waitzman, Joshua S; Rice, Sarah E

2014-01-01

159

Dynamic Positioning of Mitotic Spindles in Yeast:  

PubMed Central

In the budding yeast Saccharomyces cerevisiae, movement of the mitotic spindle to a predetermined cleavage plane at the bud neck is essential for partitioning chromosomes into the mother and daughter cells. Astral microtubule dynamics are critical to the mechanism that ensures nuclear migration to the bud neck. The nucleus moves in the opposite direction of astral microtubule growth in the mother cell, apparently being “pushed” by microtubule contacts at the cortex. In contrast, microtubules growing toward the neck and within the bud promote nuclear movement in the same direction of microtubule growth, thus “pulling” the nucleus toward the bud neck. Failure of “pulling” is evident in cells lacking Bud6p, Bni1p, Kar9p, or the kinesin homolog, Kip3p. As a consequence, there is a loss of asymmetry in spindle pole body segregation into the bud. The cytoplasmic motor protein, dynein, is not required for nuclear movement to the neck; rather, it has been postulated to contribute to spindle elongation through the neck. In the absence of KAR9, dynein-dependent spindle oscillations are evident before anaphase onset, as are postanaphase dynein-dependent pulling forces that exceed the velocity of wild-type spindle elongation threefold. In addition, dynein-mediated forces on astral microtubules are sufficient to segregate a 2N chromosome set through the neck in the absence of spindle elongation, but cytoplasmic kinesins are not. These observations support a model in which spindle polarity determinants (BUD6, BNI1, KAR9) and cytoplasmic kinesin (KIP3) provide directional cues for spindle orientation to the bud while restraining the spindle to the neck. Cytoplasmic dynein is attenuated by these spindle polarity determinants and kinesin until anaphase onset, when dynein directs spindle elongation to distal points in the mother and bud.

Yeh, Elaine; Yang, Charlie; Chin, Elaine; Maddox, Paul; Salmon, E. D.; Lew, Daniel J.; Bloom, Kerry

2000-01-01

160

Collecting Inexpensive High Resolution Aerial and Stereo Images of Small to Mid-Scale Geomorphic and Tectonic Features  

Microsoft Academic Search

Methods for collecting accurate, mm- to cm-scale stereoscopic aerial imagery of both small- and mid-scale geomorphic features are developed for a one-time cost of under $1500. High resolution aerial images are valuable for documenting and analyzing small- to mid-scale geomorphic and tectonic features. However, collecting images of mid-scale features such as landslides, rock glaciers, fault scarps, and cinder cones is

R. J. Wheelwright; W. S. White; J. B. Willis

2010-01-01

161

Qualitative Features of Cyclones triggering high precipitation events in the Island of Crete, Eastern Mediterranean.  

NASA Astrophysics Data System (ADS)

There are many cases where high precipitation or even worse flood events are provoked by cyclonic atmospheric circulation patterns of similar characteristics. In this study, an attempt was made to investigate the features of the cyclones related to these high precipitation events as well as possible correlation of the precipitation characteristics to these cyclones. A statistical analysis of the features of cyclones affecting Crete was performed over a 30-year period (1979-2011). The cyclones identification and characteristics were extracted with the aid of the Melbourne University automatic cyclone finding and tracking scheme (CTS) based on ERA Interim reanalysis datasets. A number of high precipitation events were defined with a threshold criterion based on a dataset of 53 daily precipitation records over the Island of Crete. Track selection was performed using as second criterion the cyclone distance from the study area. The track points of cyclones affecting Crete found to be related to specific rain events where further analyzed in terms of origination, direction and position. Average values of characteristics were also estimated such as the radius, pressure, depth and East/North velocity for the cyclones affecting Crete. The analysis was also extended concerning seasonality (winter, spring, autumn) and locality (eastern, central or western part of the study site) of the events. In all cases cyclones affecting Crete seem to originate mostly Northwest (~55%) and Southwest (~15%) of Crete having a Southeast (~55%) and Northeast (~15%) direction, correspondingly. Also for the majority of the events (>65%) cyclones are mainly attributed to the characteristics of a strong closed system of relatively long duration and track length.

Iordanidou, Vasiliki; Koutroulis, Aristeidis; Tsanis, Ioannis; Flocas, Helena

2013-04-01

162

Mos oncogene product associates with kinetochores in mammalian somatic cells and disrupts mitotic progression.  

PubMed Central

The mos protooncogene has opposing effects on cell cycle progression. It is required for reinitiation of meiotic maturation and for meiotic progression through metaphase II, yet it is an active component of cytostatic factor. mos is a potent oncogene in fibroblasts, but high levels of expression are lethal. The lethality of mos gene expression in mammalian cells could be a consequence of a blockage induced by its cytostatic factor-related activity, which may appear at high dosage in mitotic cells. We have directly tested whether expression of the Mos protein can block mitosis in mammalian cells by microinjecting a fusion protein between Escherichia coli maltose-binding protein and Xenopus c-Mos into PtK1 epithelial cells and analyzing the cells by video time-lapse and immunofluorescence microscopy. Time-course analyses showed that Mos blocked mitosis by preventing progression to a normal metaphase. Chromosomes frequently failed to attain a bipolar orientation and were found near one pole. Injection of a kinase-deficient mutant Mos had no effect on mitosis, indicating that the blockage of mitotic progression required Mos kinase activity. Antitubulin immunostaining of cells blocked by Mos showed that microtubules were present but that spindle morphology was abnormal. Immunostaining for the Mos fusion protein showed that both wild-type and kinase mutant proteins localized at the kinetochores. Our results suggest that mitotic blockage by Mos may result from an action of the Mos kinase on the kinetochores, thus increasing chromosome instability and preventing normal congression. Images

Wang, X M; Yew, N; Peloquin, J G; Vande Woude, G F; Borisy, G G

1994-01-01

163

Mitotic catastrophe and cell death induced by depletion of centrosomal proteins.  

PubMed

Mitotic catastrophe, which refers to cell death or its prologue triggered by aberrant mitosis, can be induced by a heterogeneous group of stimuli, including chromosome damage or perturbation of the mitotic apparatus. We investigated the mechanism of mitotic catastrophe and cell death induced by depletion of centrosomal proteins that perturbs microtubule organization. We transfected cells harboring wild-type or mutated p53 with siRNAs targeting Aurora A, ninein, TOG, TACC3, ?-tubulin, or pericentriolar material-1, and monitored the effects on cell death. Knockdown of Aurora A, ninein, TOG, and TACC3 led to cell death, regardless of p53 status. Knockdown of Aurora A, ninein, and TOG, led to aberrant spindle formation and subsequent cell death, which was accompanied by several features of apoptosis, including nuclear condensation and Annexin V binding in HeLa cells. During this process, cleavage of poly(ADP-ribose) polymerase-1, caspase-3, and caspase-9 was detected, but cleavage of caspase-8 was not. Cell death, monitored by time-lapse imaging, occurred during both interphase and M phase. In cells depleted of a centrosomal protein (Aurora A, ninein, or TOG), the rate of cell death was higher if the cells were cotransfected with siRNA against BubR1 or Mad2 than if they were transfected with siRNA against Bub1 or a control siRNA. These results suggest that metaphase arrest is necessary for the mitotic catastrophe and cell death caused by depletion of centrosomal proteins. Knockdown of centrosomal proteins led to increased phosphorylation of Chk2. Enhanced p-Chk2 localization was also observed at the centrosome in cells arrested in M phase, as well as in the nuclei of dying cells. Cotransfection of siRNAs against Chk2, in combination with depletion of a centrosomal protein, decreased the amount of cell death. Thus, Chk2 activity is indispensable for apoptosis after mitotic catastrophe induced by depletion of centrosomal proteins that perturbs microtubule organization. PMID:23598415

Kimura, M; Yoshioka, T; Saio, M; Banno, Y; Nagaoka, H; Okano, Y

2013-01-01

164

Bayesian Multiscale Analysis of X-Ray Jet Features in High Redshift Quasars  

NASA Astrophysics Data System (ADS)

X-ray emission of powerful quasar jets may be a result of the inverse Compton (IC) process in which the Cosmic Microwave Background (CMB) photons gain energy by interactions with the jet’s relativistic electrons. However, there is no definite evidence that IC/CMB process is responsible for the observed X-ray emission of large scale jets. A step toward understanding the X-ray emission process is to study the Radio and X-ray morphologies of the jet. We implement a sophisticated Bayesian image analysis program, Low-count Image Reconstruction and Analysis (LIRA) (Esch et al. 2004; Conners & van Dyk 2007), to analyze jet features in 11 Chandra images of high redshift quasars (z ~ 2 - 4.8). Out of the 36 regions where knots are visible in the radio jets, nine showed detectable X-ray emission. We measured the ratios of the X-ray and radio luminosities of the detected features and found that they are consistent with the CMB radiation relationship. We derived a range of the bulk lorentz factor (?) for detected jet features under the CMB jet emission model. There is no discernible trend of ? with redshift within the sample. The efficiency of the X-ray emission between the detected jet feature and the corresponding quasar also shows no correlation with redshift. This work is supported in part by the National Science Foundation REU and the Department of Defense ASSURE programs under NSF Grant no.1262851 and by the Smithsonian Institution, and by NASA Contract NAS8-39073 to the Chandra X-ray Center (CXC). This research has made use of data obtained from the Chandra Data Archive and Chandra Source Catalog, and software provided by the CXC in the application packages CIAO, ChIPS, and Sherpa. We thank Teddy Cheung for providing the VLA radio images. Connors, A., & van Dyk, D. A. 2007, Statistical Challenges in Modern Astronomy IV, 371, 101 Esch, D. N., Connors, A., Karovska, M., & van Dyk, D. A. 2004, ApJ, 610, 1213

McKeough, Kathryn; Siemiginowska, A.; Kashyap, V.; Stein, N.

2014-01-01

165

Belt-oriented RADON transform and its application to extracting features from high-resolution remotely sensed images  

NASA Astrophysics Data System (ADS)

Theory of belt-oriented RADON transform is developed, and applied to extracting features from high-resolution remote sense images. By several typical experiments it is proved that belt-oriented Radon transform is powerful in extracting belt features, but Radon transform (line-oriented Radon transform called by author) is unavailable.

Wang, Ruifu; Zhang, Jie; Huang, Jianbo; Chen, Miao; Leng, Xiuhua

2003-05-01

166

Design features of a high-intensity, cesium-sputter/plasma-sputter negative ion source  

SciTech Connect

A versatile, high-intensity, negative ion source has been designed and is now under construction which can be operated in either the cesium-sputter or plasma-sputter mode. The cesium-sputter mode can be effected by installation of a newly designed conical-geometry cesium-surface ionizer; for operation in the plasma-sputter mode, the surface ionizer is removed and either a hot-filament or RIF antenna plasma-discharge igniter is installed. A multicusp magnetic field is specifically provided confining the plasma in the radial direction when the plasma-sputter mode is selected. This arrangement allows comparison of the two modes of operation. Brief descriptions of the design features, ion optics, and anticipated performances of the two source geometries will be presented in this report.

Alton, G.D.; Mills, G.D. [Oak Ridge National Lab., TN (United States); Dellwo, J. [ORNL and Joint Institute for Heavy Ion Research, Oak Ridge, TN (United States)

1993-12-31

167

A Small Mission Featuring an Imaging X-ray Polarimeter with High Sensitivity  

NASA Technical Reports Server (NTRS)

We present a detailed description of a small mission capable of obtaining high precision and meaningful measurement of the X-ray polarization of a variety of different classes of cosmic X-ray sources. Compared to other ideas that have been suggested this experiment has demonstrated in the laboratory a number of extremely important features relevant to the ultimate selection of such a mission by a funding agency. The most important of these questions are: 1) Have you demonstrated the sensitivity to a polarized beam at the energies of interest (i.e. the energies which represent the majority (not the minority) of detected photons from the X-ray source of interest? 2) Have you demonstrated that the device's sensitivity to an unpolarized beam is really negligible and/or quantified the impact of any systematic effects upon actual measurements? We present our answers to these questions backed up by laboratory measurements and give an overview of the mission.

Weisskopf, Martin C.; Baldini, Luca; Bellazini, Ronaldo; Brez, Alessandro; Costa, Enrico; Dissley, Richard; Elsner, Ronald; Fabiani, Sergio; Matt, Giorgio; Minuti, Massimo; Mulieri, Fabio; O'Dell, Steve; Pinchera, Michelle; Ramsey, Brian; Rubini, Alda; Sgro, Carmelo; Soffitta, Paolo; Spandre, Gloria

2013-01-01

168

Leakage Reduction Effect by Multiple Cracking Feature of High Performance Fiber Reinforced Cement Composite  

NASA Astrophysics Data System (ADS)

In a kind of concrete canal, repair materials are applied for recovery of the deteriorated functions. However, due to the re-cracking of the repair material caused by the fluctuations of the crack width, there is a great possibility that the functional deterioration reoccurs after the repair. In this research, High Performance Fiber Reinforced Cement Composite (HPFRCC), which has multiple cracking feature, was evaluated as a repair material to prevent the functional deterioration after the repair. HPFRCC and mortar specimens were cracked and examined by permeability test. As a result, it was clarified that the leakage from the HPFRCC specimen was very little compared with the leakage from the mortar specimen. Moreover, it was confirmed that the leakage from the narrow cracks were gradually decreased.

Ueno, Kazuhiro; Natsuka, Isamu; Ishii, Masayuki

169

Nano features of Al/Au ultrasonic bond interface observed by high resolution transmission electron microscopy  

SciTech Connect

Nano-scale interfacial details of ultrasonic AlSi1 wire wedge bonding to a Au/Ni/Cu pad were investigated using high resolution transmission electron microscopy (HRTEM). The intermetallic phase Au{sub 8}Al{sub 3} formed locally due to diffusion and reaction activated by ultrasound at the Al/Au bond interface. Multilayer sub-interfaces roughly parallel to the wire/pad interface were observed among this phase, and interdiffusional features near the Au pad resembled interference patterns, alternately dark and bright bars. Solid-state diffusion theory cannot be used to explain why such a thick compound formed within milliseconds at room temperature. The major formation of metallurgical bonds was attributed to ultrasonic cyclic vibration.

Ji Hongjun [Harbin Institute of Technology Shenzhen Graduate School, HIT Campus, Shenzhen University Town, Xili, Shenzhen 518055 (China); State Key Laboratory of Advanced Welding Production Technology, Harbin Institute of Technology, 92, Xidazhi Street, Nangang, Harbin 150001 (China); Li Mingyu [Harbin Institute of Technology Shenzhen Graduate School, HIT Campus, Shenzhen University Town, Xili, Shenzhen 518055 (China)], E-mail: myli@hit.edu.cn; Kim, Jong-Myung; Kim, Dae-Won [Jeonnam Provincial College, Jeonnam 517-802 (Korea, Republic of); Wang Chunqing [State Key Laboratory of Advanced Welding Production Technology, Harbin Institute of Technology, 92, Xidazhi Street, Nangang, Harbin 150001 (China)

2008-10-15

170

Subresolution assist feature implementation for high-performance logic gate-level lithography  

NASA Astrophysics Data System (ADS)

This paper investigates the implementation of sub-resolution assist features (SRAFs) in high performance logic designs for the poly-gate conductor level. We will discuss the concepts used for SRAF rule generation, SRAF data preparation and what we term 'binary' optical proximity correction (OPC) to prevent catastrophic line-width problems. Lithographic process window (PW) data obtained with SRAFs will be compared to PW data obtained without SRAF. SRAM cells are shown printed with annular illumination and SRAFs, for both the 130 nm and 100 nm logic nodes as defined by the International Technology Roadmap for Semiconductors (ITRS). This study includes a comparison of the experimental results of SRAMs printed from designs corrected with rule-based OPC to those printed from designs corrected with model-based OPC.

Gabor, Allen H.; Bruce, James A.; Chu, William; Ferguson, Richard A.; Fonseca, Carlos A.; Gordon, Ronald L.; Jantzen, Kenneth R.; Khare, Mukesh; Lavin, Mark A.; Lee, Woo-Hyeong; Liebmann, Lars W.; Muller, Karl P.; Rankin, Jed H.; Varekamp, Patrick; Zach, Franz X.

2002-07-01

171

Karyotype Evolution in Tilapia: Mitotic and Meiotic Chromosome Analysis of Oreochromis Karongae and O. Niloticus × O. Karongae Hybrids  

Microsoft Academic Search

The karyotype of Oreochromis species is considered to be highly conserved, with a diploid chromosome complement of 2n = 44. Here we show, by analysis of mitotic and meiotic chromosomes, that the karyotype of O. karongae, one of the Lake Malawi ‘chambo’ species, is 2n = 38. This difference in chromosome number does not prevent the production of inter-specific hybrids

S. C. Harvey; R. Campos-Ramos; D. D. Kennedy; M. T. Ezaz; N. R. Bromage; D. K. Griffin; D. J. Penman

2002-01-01

172

Mitotic Chromosome Loss in a Disomic Haploid of SACCHAROMYCES CEREVISIAE  

PubMed Central

Experiments designed to characterize the incidence of mitotic chromosome loss in a yeast disomic haploid were performed. The selective methods employed utilize the non-mating property of strains disomic for linkage group III and heterozygous at the mating type locus. The principal findings are: (1) The frequency of spontaneous chromosome loss in the disome is of the order 10-4 per cell; this value approximates the frequency in the same population of spontaneous mitotic exchange resulting in homozygosity at the mating type locus. (2) The recovered diploids are pure clones, and thus represent unique events in the disomic haploid. (3) Of the euploid chromosomes recovered after events leading to chromosome loss, approximately 90% retain the parental marker configuration expected from segregation alone; however, the remainder are recombinant for marker genes, and are the result of mitotic exchanges in the disome, especially in regions near the centromere. The recombinant proportion significantly exceeds that expected if chromosome loss and mitotic exchange in the disome were independent events. The data are consistent with a model proposing mitotic nondisjunction as the event responsible for chromosome loss in the disomic haploid.

Campbell, D. A.; Fogel, S.; Lusnak, K.

1975-01-01

173

Robust mitotic entry is ensured by a latching switch  

PubMed Central

Summary 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.

Tuck, Chloe; Zhang, Tongli; Potapova, Tamara; Malumbres, Marcos; Novak, Bela

2013-01-01

174

Relative contributions of chromatin and kinetochores to mitotic spindle assembly  

PubMed Central

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

Loncarek, Jadranka; Kalab, Petr; Khodjakov, Alexey

2009-01-01

175

CK1 is required for a mitotic checkpoint that delays cytokinesis.  

PubMed

Failure to accurately partition genetic material during cell division causes aneuploidy and drives tumorigenesis. Cell-cycle checkpoints safeguard cells from such catastrophes by impeding cell-cycle progression when mistakes arise. FHA-RING E3 ligases, including human RNF8 and CHFR and fission yeast Dma1, relay checkpoint signals by binding phosphorylated proteins via their FHA domains and promoting ubiquitination of downstream targets. Upon mitotic checkpoint activation, S. pombe Dma1 concentrates at spindle pole bodies (SPBs) in an FHA-dependent manner and ubiquitinates Sid4, a scaffold of Polo kinase, to suspend cytokinesis. However, the kinase or kinases that phosphoprime Sid4 for Dma1-mediated ubiquitination are unknown. Here, we report that the highly conserved protein kinase CK1 transmits the signal necessary to stall cytokinesis by phosphopriming Sid4 for Dma1-mediated ubiquitination. Like Dma1, CK1 accumulates at SPBs during a mitotic arrest and associates stably with SPB components, including Sid4. Our results establish CK1 as an integral component of a mitotic, ubiquitin-mediated checkpoint pathway. PMID:24055157

Johnson, Alyssa E; Chen, Jun-Song; Gould, Kathleen L

2013-10-01

176

Twinning and mitotic crossing-over: some possibilities and their implications.  

PubMed Central

Mitotic crossing-over does occur in man and is much more frequent and important than generally assumed. Its postzygotic occurrence before an embryo differentiates into MZ twins is theoretically predicted to have disrupting effects on genomic imprinting and cis-acting sequences, with consequences ranging from early lethality to MZ twin discordance. Some predictions are at odds with classical views on twinning and include a high discordance rate of MZ twins for some genetic diseases. A review of MZ twin discordance and an attempt at explaining some of the data lead one to hypothesize both the existence of a sex differences in the rate of mitotic crossing-over and the impossibility for crossed X chromosomes to undergo inactivation. The close interrelationship of twinning and midline malformations further suggests a major role of mitotic crossing-over in the induction of the twinning process itself. The model can be tested with molecular methods and provides a new approach for the gene mapping of so-called multifactorial diseases and of rarer disorders with apparently irregular inheritance.

Cote, G B; Gyftodimou, J

1991-01-01

177

Transcriptional response to stress in the dynamic chromatin environment of cycling and mitotic cells  

PubMed Central

Heat shock factors (HSFs) are the master regulators of transcription under protein-damaging conditions, acting in an environment where the overall transcription is silenced. We determined the genomewide transcriptional program that is rapidly provoked by HSF1 and HSF2 under acute stress in human cells. Our results revealed the molecular mechanisms that maintain cellular homeostasis, including HSF1-driven induction of polyubiquitin genes, as well as HSF1- and HSF2-mediated expression patterns of cochaperones, transcriptional regulators, and signaling molecules. We characterized the genomewide transcriptional response to stress also in mitotic cells where the chromatin is tightly compacted. We found a radically limited binding and transactivating capacity of HSF1, leaving mitotic cells highly susceptible to proteotoxicity. In contrast, HSF2 occupied hundreds of loci in the mitotic cells and localized to the condensed chromatin also in meiosis. These results highlight the importance of the cell cycle phase in transcriptional responses and identify the specific mechanisms for HSF1 and HSF2 in transcriptional orchestration. Moreover, we propose that HSF2 is an epigenetic regulator directing transcription throughout cell cycle progression.

Vihervaara, Anniina; Sergelius, Christian; Vasara, Jenni; Blom, Malin A. H.; Elsing, Alexandra N.; Roos-Mattjus, Pia; Sistonen, Lea

2013-01-01

178

PLK1 Phosphorylates Mitotic Centromere-associated Kinesin and Promotes Its Depolymerase Activity*  

PubMed Central

During cell division, interaction between kinetochores and dynamic spindle microtubules governs chromosome movements. The microtubule depolymerase mitotic centromere-associated kinesin (MCAK) is a key regulator of mitotic spindle assembly and dynamics. However, the regulatory mechanisms underlying its depolymerase activity during the cell cycle remain elusive. Here, we showed that PLK1 is a novel regulator of MCAK in mammalian cells. MCAK interacts with PLK1 in vitro and in vivo. The neck and motor domain of MCAK associates with the kinase domain of PLK1. MCAK is a novel substrate of PLK1, and the phosphorylation stimulates its microtubule depolymerization activity of MCAK in vivo. Overexpression of a polo-like kinase 1 phosphomimetic mutant MCAK causes a dramatic increase in misaligned chromosomes and in multipolar spindles in mitotic cells, whereas overexpression of a nonphosphorylatable MCAK mutant results in aberrant anaphase with sister chromatid bridges, suggesting that precise regulation of the MCAK activity by PLK1 phosphorylation is critical for proper microtubule dynamics and essential for the faithful chromosome segregation. We reasoned that dynamic regulation of MCAK phosphorylation by PLK1 is required to orchestrate faithful cell division, whereas the high levels of PLK1 and MCAK activities seen in cancer cells may account for a mechanism underlying the pathogenesis of genomic instability.

Zhang, Liangyu; Shao, Hengyi; Huang, Yuejia; Yan, Feng; Chu, Youjun; Hou, Hai; Zhu, Mei; Fu, Chuanhai; Aikhionbare, Felix; Fang, Guowei; Ding, Xia; Yao, Xuebiao

2011-01-01

179

Prioritizing spatial accuracy in high-resolution fMRI data using multivariate feature weight mapping.  

PubMed

Although ultra-high-field fMRI at field strengths of 7T or above provides substantial gains in BOLD contrast-to-noise ratio, when very high-resolution fMRI is required such gains are inevitably reduced. The improvement in sensitivity provided by multivariate analysis techniques, as compared with univariate methods, then becomes especially welcome. Information mapping approaches are commonly used, such as the searchlight technique, which take into account the spatially distributed patterns of activation in order to predict stimulus conditions. However, the popular searchlight decoding technique, in particular, has been found to be prone to spatial inaccuracies. For instance, the spatial extent of informative areas is generally exaggerated, and their spatial configuration is distorted. We propose the combination of a non-parametric and permutation-based statistical framework with linear classifiers. We term this new combined method Feature Weight Mapping (FWM). The main goal of the proposed method is to map the specific contribution of each voxel to the classification decision while including a correction for the multiple comparisons problem. Next, we compare this new method to the searchlight approach using a simulation and ultra-high-field 7T experimental data. We found that the searchlight method led to spatial inaccuracies that are especially noticeable in high-resolution fMRI data. In contrast, FWM was more spatially precise, revealing both informative anatomical structures as well as the direction by which voxels contribute to the classification. By maximizing the spatial accuracy of ultra-high-field fMRI results, global multivariate methods provide a substantial improvement for characterizing structure-function relationships. PMID:24795548

Stelzer, Johannes; Buschmann, Tilo; Lohmann, Gabriele; Margulies, Daniel S; Trampel, Robert; Turner, Robert

2014-01-01

180

Reinforcement Learning on Slow Features of High-Dimensional Input Streams  

PubMed Central

Humans and animals are able to learn complex behaviors based on a massive stream of sensory information from different modalities. Early animal studies have identified learning mechanisms that are based on reward and punishment such that animals tend to avoid actions that lead to punishment whereas rewarded actions are reinforced. However, most algorithms for reward-based learning are only applicable if the dimensionality of the state-space is sufficiently small or its structure is sufficiently simple. Therefore, the question arises how the problem of learning on high-dimensional data is solved in the brain. In this article, we propose a biologically plausible generic two-stage learning system that can directly be applied to raw high-dimensional input streams. The system is composed of a hierarchical slow feature analysis (SFA) network for preprocessing and a simple neural network on top that is trained based on rewards. We demonstrate by computer simulations that this generic architecture is able to learn quite demanding reinforcement learning tasks on high-dimensional visual input streams in a time that is comparable to the time needed when an explicit highly informative low-dimensional state-space representation is given instead of the high-dimensional visual input. The learning speed of the proposed architecture in a task similar to the Morris water maze task is comparable to that found in experimental studies with rats. This study thus supports the hypothesis that slowness learning is one important unsupervised learning principle utilized in the brain to form efficient state representations for behavioral learning.

Legenstein, Robert; Wilbert, Niko; Wiskott, Laurenz

2010-01-01

181

Prioritizing spatial accuracy in high-resolution fMRI data using multivariate feature weight mapping  

PubMed Central

Although ultra-high-field fMRI at field strengths of 7T or above provides substantial gains in BOLD contrast-to-noise ratio, when very high-resolution fMRI is required such gains are inevitably reduced. The improvement in sensitivity provided by multivariate analysis techniques, as compared with univariate methods, then becomes especially welcome. Information mapping approaches are commonly used, such as the searchlight technique, which take into account the spatially distributed patterns of activation in order to predict stimulus conditions. However, the popular searchlight decoding technique, in particular, has been found to be prone to spatial inaccuracies. For instance, the spatial extent of informative areas is generally exaggerated, and their spatial configuration is distorted. We propose the combination of a non-parametric and permutation-based statistical framework with linear classifiers. We term this new combined method Feature Weight Mapping (FWM). The main goal of the proposed method is to map the specific contribution of each voxel to the classification decision while including a correction for the multiple comparisons problem. Next, we compare this new method to the searchlight approach using a simulation and ultra-high-field 7T experimental data. We found that the searchlight method led to spatial inaccuracies that are especially noticeable in high-resolution fMRI data. In contrast, FWM was more spatially precise, revealing both informative anatomical structures as well as the direction by which voxels contribute to the classification. By maximizing the spatial accuracy of ultra-high-field fMRI results, global multivariate methods provide a substantial improvement for characterizing structure-function relationships.

Buschmann, Tilo; Lohmann, Gabriele; Margulies, Daniel S.; Trampel, Robert; Turner, Robert

2014-01-01

182

Morphological features of Triassic and Late Cretaceous high-latitude radiolarian assemblages (comparative analysis)  

NASA Astrophysics Data System (ADS)

High-latitude radiolarian assemblages of Mesozoic represent particular interest for Boreal-Tethyan correlation of Mesozoic as well as for their paleobiogeography. Radiolarians are the only planktonic protists that present both in low- and high-latitude Mesozoic sections, therefore they have high importance. The aim of this work is to distinguish common and different features of Triassic and Late Cretaceous high-latitude assemblages of Radiolaria during their comparative analysis. We use material from Triassic of Omolon Massif (NE Siberia) (Bragin, Egorov, 2001) and Kotel'nyi Island (Arctic) (Bragin, Bragina, 2009; Bragin, in press) and Late Cretaceous of Western Siberia (Amon, 2000) and Kamchatka Peninsula (Vishnevskaya, 2005; Bragina, 1991). The main trends of radiolarian assemblages from these sections are: quantitative domination of some taxa, presence of characteristic high-latitude taxa that are absent or very rare in low-latitude regions, and relatively low taxonomic diversity with absence of many high taxa and many morphotypes. We made following conclusions after comparative analysis: 1. Triassic assemblages are dominated by morphotypes with bipolar main spines (Pseudostylosphaera and similar forms), and by pylomate forms (Glomeropyle). Genus Glomeropyle has bipolar distribution pattern and it is typically high-latitude taxon. Late Cretaceous assemblages are dominated by forms with bipolar three-bladed main spines (Amphisphaera, Protoxiphotractus, Stylosphaera), by prunoid morphotypes (Amphibrachium, Prunobrachium), discoid spongy forms (Orbiculiforma, Spongodiscus) by three-rayed (Paronaella, Spongotripus), four-rayed (Crucella, Histiastrum) and multirayed stauraxon forms (Pentinastrum, Multastrum). Pylomate forms (Spongopyle) are present in the Late Cretaceous high-latitude assemblages but not so common. 2. Spherical forms with spines that possess apophyses (Kahlerosphaera, Dumitricasphaera) are common for Triassic high-latitude areas, but not present in the Cretaceous assemblages. Spherical forms with hollow, commonly twisted spines (Capnuchosphaera) and with two-bladed spines (Zhamojdasphaera) are present only in the Triassic assemblages. 3. Saturnalids are present both in Triassic and Late Cretaceous high-latitude assemblages but not common. 4. Stauraxon three-rayed forms (like Paronaella) are very rare in the Triassic high-latitude assemblages but very common in the Late Cretaceous ones. Some Late Cretaceous morphotypes of this type have bipolar distribution pattern (Spongotripus). 5. Discoidal forms in the Triassic high-latitude assemblages are represented by Tetraspongodiscus - small forms with 4 radial spines. Cretaceous discoids are highly more diverse and are represented by numerous taxa with variable morphology. 6. Multicyrtoid nassellarians with longitudinal ridges are very rare in the Triassic (Whalenella), but very common in the Late Cretaceous (Pseudodictyomitra, Dictyomitra). Multicyrtoid Stichomitra-type specimens are present both in the Triassic and Cretaceous assemblages. 7. Hat-shaped and highly ornamented Nassellaria are almost absent in the high-latitude Triassic and Late Cretaceous assemblages. 8. During long evolutionary history of Radiolaria typically boreal forms strongly differ, and only morphotypes with bipolar main spines and pylomate forms retain their significance as high-latitude indicators.

Bragin, Nikita; Bragina, Liubov

2010-05-01

183

Stimulated Raman scattering as an explanation for the extreme high-velocity features of water maser emission  

Microsoft Academic Search

Extreme high-velocity features in the water maser spectra with velocity shifts of about +\\/- 900 km\\/s have recently been detected in the extragalactic water maser source, NGC 4258. We explain these extreme high-velocity features of water masers by stimulated Raman scattering in the plasma of the electron density of about 106-107\\/cu cm. For the Raman masers to occur, the brightness

Shuji Deguchi

1994-01-01

184

Extraction of Airport Features from High Resolution Satellite Imagery for Design and Risk Assessment  

NASA Technical Reports Server (NTRS)

The LPA Group, consisting of 17 offices located throughout the eastern and central United States is an architectural, engineering and planning firm specializing in the development of Airports, Roads and Bridges. The primary focus of this ARC project is concerned with assisting their aviation specialists who work in the areas of Airport Planning, Airfield Design, Landside Design, Terminal Building Planning and design, and various other construction services. The LPA Group wanted to test the utility of high-resolution commercial satellite imagery for the purpose of extracting airport elevation features in the glide path areas surrounding the Columbia Metropolitan Airport. By incorporating remote sensing techniques into their airport planning process, LPA wanted to investigate whether or not it is possible to save time and money while achieving the equivalent accuracy as traditional planning methods. The Affiliate Research Center (ARC) at the University of South Carolina investigated the use of remotely sensed imagery for the extraction of feature elevations in the glide path zone. A stereo pair of IKONOS panchromatic satellite images, which has a spatial resolution of 1 x 1 m, was used to determine elevations of aviation obstructions such as buildings, trees, towers and fence-lines. A validation dataset was provided by the LPA Group to assess the accuracy of the measurements derived from the IKONOS imagery. The initial goal of this project was to test the utility of IKONOS imagery in feature extraction using ERDAS Stereo Analyst. This goal was never achieved due to problems with ERDAS software support of the IKONOS sensor model and the unavailability of imperative sensor model information from Space Imaging. The obstacles encountered in this project pertaining to ERDAS Stereo Analyst and IKONOS imagery will be reviewed in more detail later in this report. As a result of the technical difficulties with Stereo Analyst, ERDAS OrthoBASE was used to derive aviation obstruction measurements for this project. After collecting ancillary data such as GPS locations, South Carolina Geodetic Survey and Aero Dynamics ground survey points to set up the OrthoBASE Block File, measurements were taken of the various glide path obstructions and compared to the validation dataset. This process yielded the following conclusions: The IKONOS stereo model in conjunction with Imagine OrthoBASE can provide The LPA Group with a fast and cost efficient method for assessing aviation obstructions. Also, by creating our own stereo model we achieved any accuracy better currently available commercial products.

Robinson, Chris; Qiu, You-Liang; Jensen, John R.; Schill, Steven R.; Floyd, Mike

2001-01-01

185

Evaluating feature selection strategies for high dimensional, small sample size datasets.  

PubMed

In this work, we analyze and evaluate different strategies for comparing Feature Selection (FS) schemes on High Dimensional (HD) biomedical datasets (e.g. gene and protein expression studies) with a small sample size (SSS). Additionally, we define a new feature, Robustness, specifically for comparing the ability of an FS scheme to be invariant to changes in its training data. While classifier accuracy has been the de facto method for evaluating FS schemes, on account of the curse of dimensionality problem, it might not always be the appropriate measure for HD/SSS datasets. SSS lends the dataset a higher probability of containing data that is not representative of the true distribution of the whole population. However, an ideal FS scheme must be robust enough to produce the same results each time there are changes to the training data. In this study, we employed the robustness performance measure in conjunction with classifier accuracy (measured via the K-Nearest Neighbor and Random Forest classifiers) to quantitatively compare five different FS schemes (T-test, F-test, Kolmogorov-Smirnov Test, Wilks Lambda Test and Wilcoxon Rand Sum Test) on 5 HD/SSS gene and protein expression datasets corresponding to ovarian cancer, lung cancer, bone lesions, celiac disease, and coronary heart disease. Of the five FS schemes compared, the Wilcoxon Rand Sum Test was found to outperform other FS schemes in terms of classification accuracy and robustness. Our results suggest that both classifier accuracy and robustness should be considered when deciding on the appropriate FS scheme for HD/SSS datasets. PMID:22254468

Golugula, Abhishek; Lee, George; Madabhushi, Anant

2011-01-01

186

Detailed Hydrographic Feature Extraction from High-Resolution LiDAR Data  

SciTech Connect

Detailed hydrographic feature extraction from high-resolution light detection and ranging (LiDAR) data is investigated. Methods for quantitatively evaluating and comparing such extractions are presented, including the use of sinuosity and longitudinal root-mean-square-error (LRMSE). These metrics are then used to quantitatively compare stream networks in two studies. The first study examines the effect of raster cell size on watershed boundaries and stream networks delineated from LiDAR-derived digital elevation models (DEMs). The study confirmed that, with the greatly increased resolution of LiDAR data, smaller cell sizes generally yielded better stream network delineations, based on sinuosity and LRMSE. The second study demonstrates a new method of delineating a stream directly from LiDAR point clouds, without the intermediate step of deriving a DEM. Direct use of LiDAR point clouds could improve efficiency and accuracy of hydrographic feature extractions. The direct delineation method developed herein and termed “mDn”, is an extension of the D8 method that has been used for several decades with gridded raster data. The method divides the region around a starting point into sectors, using the LiDAR data points within each sector to determine an average slope, and selecting the sector with the greatest downward slope to determine the direction of flow. An mDn delineation was compared with a traditional grid-based delineation, using TauDEM, and other readily available, common stream data sets. Although, the TauDEM delineation yielded a sinuosity that more closely matches the reference, the mDn delineation yielded a sinuosity that was higher than either the TauDEM method or the existing published stream delineations. Furthermore, stream delineation using the mDn method yielded the smallest LRMSE.

Danny L. Anderson

2012-05-01

187

Retrieval Using Texture Features in High Resolution Multi-spectral Satellite Imagery  

SciTech Connect

Texture features have long been used in remote sensing applications to represent and retrieve image regions similar to a query region. Various representations of texture have been proposed based on the Fourier power spectrum, spatial co-occurrence, wavelets, Gabor filters, etc. These representations vary in their computational complexity and their suitability for representing different region types. Much of the work done thus far has focused on panchromatic imagery at low to moderate spatial resolutions, such as images from Landsat 1-7 which have a resolution of 15-30 m/pixel, and from SPOT 1-5 which have a resolution of 2.5-20 m/pixel. However, it is not clear which texture representation works best for the new classes of high resolution panchromatic (60-100 cm/pixel) and multi-spectral (4 bands for red, green, blue, and near infra-red at 2.4-4 m/pixel) imagery. It is also not clear how the different spectral bands should be combined. In this paper, we investigate the retrieval performance of several different texture representations using multi-spectral satellite images from IKONOS. A query-by-example framework, along with a manually chosen ground truth dataset, allows different combinations of texture representations and spectral bands to be compared. We focus on the specific problem of retrieving inhabited regions from images of urban and rural scenes. Preliminary results show that (1) the use of all spectral bands improves the retrieval performance, and (2) co-occurrence, wavelet and Gabor texture features perform comparably.

Newsam, S D; Kamath, C

2004-01-22

188

BeppoSAX detection of highly ionized emission and absorption features in M81  

NASA Astrophysics Data System (ADS)

The LINER nucleus of the nearby spiral galaxy M81 was pointed by BeppoSAX, which caught it at the highest (2-10) keV flux level observed so far. The LECS, MECS and PDS data (extending over 0.1-100 keV) are used to investigate the similarities and differences between LINERs and AGNs. The continuum is well fitted by a power law of photon index ?~1.84, modified by little absorption due to cold material; signs of reflection from the optically thick material of an accretion disk are not observed. Instead, BeppoSAX detects a 6.7 keV emission line (confirming an ASCA result), and an absorption edge at ~8.6 keV. Both spectral features are consistent with being produced by iron at the same high ionization level, and possibly also with the same column density. We suggest that they come from transmission through a highly photoionized medium. The origin of the continuum emission is uncertain, since typical signatures of a standard accretion disk are absent, and the steep spectrum observed over (0.1-100) keV requires Compton scattering to dominate the X-ray emission even in a modeling via advection dominated accretion. .

Pellegrini, S.; Cappi, M.; Bassani, L.; Malaguti, G.; Palumbo, G. G. C.; Persic, M.

2001-12-01

189

Correlation between High Endothelial Vessels and Histopathological Features of Different Pigmented Lesions  

PubMed Central

Purpose: Tumor infiltrating lymphocytes are playing an important role in cutaneous melanoma being a strong prognostic parameter. Our goal was to study the presence of high endothelial vessels in correlation with the histopathological features in different pigmented skin lesions. Material and methods: our study group included 60 patients (20 cases with dysplastic nevi, 20 thin melanoma and 20 thick melanoma). For each patient we noted epidemiological and clinico-pathological characteristics including: age, gender, anatomic sites, regression, Breslow thickness, mitoses, Clark level and lymphocytic infiltration. Using immunohistochemistry staining we identified the presence of high endothelial vessels in our groups. Results: the most common localization of primary melanoma was trunk 57,5%, followed by extremities 35% and head 7,5%. We found positive MECA-79 vessels in 67% of primary melanoma samples and in 30% of dysplastic nevi. Lymphocytic infiltration was present in 80% samples of dysplastic nevi and 75% of primary melanomas. Using Kruskal Wallis non-parametric test we found a positive association between MECA-79+ vessels and different anatomic sites (p<0,01). We have also found a significant correlation between MECA-79+ vessels and the presence of regression in melanoma samples. In conclusion a better understanding of tumor microenvironment and mechanisms involved in anti-tumor response might play an important role in development of future melanoma therapeutic strategies.

AVRAM, GABRIELA; MIXICH, F.; IOANA, M.; PATRASCU, V; MONTEAGUDO, C.

2014-01-01

190

Mitotic figure recognition: agreement among pathologists and computerized detector.  

PubMed

Despite the prognostic importance of mitotic count as one of the components of the Bloom-Richardson grade, several studies have found that pathologists' agreement on the mitotic grade is fairly modest. Collecting a set of more than 4,200 candidate mitotic figures, we evaluate pathologists' agreement on individual figures, and train a computerized system for mitosis detection, comparing its performance to the classifications of three pathologists. The system's and the pathologists' classifications are based on evaluation of digital micrographs of hematoxylin and eosin stained breast tissue. On figures where the majority of pathologists agree on a classification, we compare the performance of the trained system to that of the individual pathologists. We find that the level of agreement of the pathologists ranges from slight to moderate, with strong biases, and that the system performs competitively in rating the ground truth set. This study is a step towards automatic mitosis count to accelerate a pathologist's work and improve reproducibility. PMID:21965283

Malon, Christopher; Brachtel, Elena; Cosatto, Eric; Graf, Hans Peter; Kurata, Atsushi; Kuroda, Masahiko; Meyer, John S; Saito, Akira; Wu, Shulin; Yagi, Yukako

2012-01-01

191

Differential mitotic responses to microtubule-stabilizing and -destabilizing drugs.  

PubMed

Although microtubule interacting agents inhibit spindle dynamics, thereby leading to a block in mitosis, we report that low concentrations of these drugs result in differential mitotic effects. Microtubule-stabilizing agents including Taxol, epothilone B, and discodermolide produce aneuploid populations of A549 cells in the absence of a mitotic block. Such aneuploid populations are diminished in an epothilone B-resistant cell line. In contrast, microtubule-destabilizing agents like colchicine, nocodazole, and vinblastine are unable to initiate aneuploidy. The aneuploid cells result from aberrant mitosis as multipolar spindles are induced by the stabilizing drugs, but not by destabilizing agents. The results suggest that the mechanism underlying aberrant mitosis may not be the same as that responsible for mitotic block, and that the former determines the sensitivity of cells to Taxol-like drugs. PMID:11929805

Chen, Jie-Guang; Horwitz, Susan Band

2002-04-01

192

Topoisomerase II is a structural component of mitotic chromosome scaffolds  

PubMed Central

We have obtained a polyclonal antibody that recognizes a major polypeptide component of chicken mitotic chromosome scaffolds. This polypeptide migrates in SDS PAGE with Mr 170,000. Indirect immunofluorescence and subcellular fractionation experiments confirm that it is present in both mitotic chromosomes and interphase nuclei. Two lines of evidence suggest that this protein is DNA topoisomerase II, an abundant nuclear enzyme that controls DNA topological states: anti-scaffold antibody inhibits the strand-passing activity of DNA topoisomerase II; and both anti-scaffold antibody and an independent antibody raised against purified bovine topoisomerase II recognize identical partial proteolysis fragments of the 170,000-mol-wt scaffold protein in immunoblots. Our results suggest that topoisomerase II may be an enzyme that is also a structural protein of interphase nuclei and mitotic chromosomes.

1985-01-01

193

Impaired Mitotic Progression and Preimplantation Lethality in Mice Lacking OMCG1, a New Evolutionarily Conserved Nuclear Protein†  

PubMed Central

While highly conserved through evolution, the cell cycle has been extensively modified to adapt to new developmental programs. Recently, analyses of mouse mutants revealed that several important cell cycle regulators are either dispensable for development or have a tissue- or cell-type-specific function, indicating that many aspects of cell cycle regulation during mammalian embryo development remain to be elucidated. Here, we report on the characterization of a new gene, Omcg1, which codes for a nuclear zinc finger protein. Embryos lacking Omcg1 die by the end of preimplantation development. 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.

Artus, Jerome; Vandormael-Pournin, Sandrine; Frodin, Morten; Nacerddine, Karim; Babinet, Charles; Cohen-Tannoudji, Michel

2005-01-01

194

Overlapping features between dedifferentiated liposarcoma and undifferentiated high-grade pleomorphic sarcoma.  

PubMed

Dedifferentiated liposarcoma (DDL), occurring in up to 10% of well differentiated liposarcoma cases, has similar histologic features to that of undifferentiated high-grade pleomorphic sarcoma (UHGPS); the former develops in a background of atypical lipomatous tumors/well differentiated liposarcoma, whereas the latter shows no specific line of differentiation. The retroperitoneum and thigh represent the most common anatomic locations for both the sarcomas. Despite their morphologic similarity, the issue of whether these 2 sarcomas share overlapping immunohistochemical and molecular features has not been well studied. We examined the expression of the lipogenic tumor-related markers peroxisome proliferator-activated receptor gamma (PPAR-gamma), CDK4, and MDM2 in 15 cases of DDL and 45 cases of retroperitoneal/thigh UHGPS. Patients with DDL ranged from 31 to 82 years (mean 63 y) with a male:female ratio of 5:3. Patients with UHGPS ranged from 14 to 80 years (mean 52 y) with a male:female ratio of 3:2. All 15 DDLs expressed CDK4 and MDM2 (100%), and 8 of 15 cases expressed PPAR-gamma (53%). Twenty-three of 45 (51%) UHGPS expressed at least 1 of these 3 markers. We also studied MDM2 and CDK4 gene amplification by fluorescence in situ hybridization in 28 immunohistochemically positive cases, including 5 DDLs and 23 UHGPSs. All 5 cases of DDL showed MDM2 and/or CDK4 amplification (100%), whereas 6 of 45 UHGPSs showed MDM2 and/or CDK4 amplification (13%). Our results demonstrate that (1) the lipogenic tumor markers CDK4 and MDM2 can be used as surrogate immunohistochemical markers for the diagnosis of malignant lipomatous tumors with high sensitivity; (2) approximately 26% of retroperitoneal/thigh UHGPS cases that were positive for PPAR-gamma, CDK4, or MDM2 by immunohistochemistry showed characteristic CDK4 and MDM2 gene amplification, suggesting that a subset of UHGPS cases represent DDL despite lacking histologic evidence of lipoblasts. PMID:19574885

Chung, Lawrance; Lau, Sean K; Jiang, Zhong; Loera, Sofia; Bedel, Victoria; Ji, Jianling; Weiss, Lawrence M; Chu, Peiguo G

2009-11-01

195

Universal features in the photoemission spectroscopy of high-temperature superconductors  

PubMed Central

The energy gap for electronic excitations is one of the most important characteristics of the superconducting state, as it directly reflects the pairing of electrons. In the copper–oxide high-temperature superconductors (HTSCs), a strongly anisotropic energy gap, which vanishes along high-symmetry directions, is a clear manifestation of the d-wave symmetry of the pairing. There is, however, a dramatic change in the form of the gap anisotropy with reduced carrier concentration (underdoping). Although the vanishing of the gap along the diagonal to the square Cu–O bond directions is robust, the doping dependence of the large gap along the Cu–O directions suggests that its origin might be different from pairing. It is thus tempting to associate the large gap with a second-order parameter distinct from superconductivity. We use angle-resolved photoemission spectroscopy to show that the two-gap behavior and the destruction of well-defined electronic excitations are not universal features of HTSCs, and depend sensitively on how the underdoped materials are prepared. Depending on cation substitution, underdoped samples either show two-gap behavior or not. In contrast, many other characteristics of HTSCs, such as the dome-like dependence of on doping, long-lived excitations along the diagonals to the Cu–O bonds, and an energy gap at the Brillouin zone boundary that decreases monotonically with doping while persisting above (the pseudogap), are present in all samples, irrespective of whether they exhibit two-gap behavior or not. Our results imply that universal aspects of high- superconductivity are relatively insensitive to differences in the electronic states along the Cu–O bond directions.

Zhao, Junjing; Chatterjee, Utpal; Ai, Dingfei; Hinks, David G.; Zheng, Hong; Gu, G. D.; Castellan, John-Paul; Rosenkranz, Stephan; Claus, Helmut; Norman, Michael R.; Randeria, Mohit; Campuzano, Juan Carlos

2013-01-01

196

Universal features in the photoemission spectroscopy of high-temperature superconductors.  

PubMed

The energy gap for electronic excitations is one of the most important characteristics of the superconducting state, as it directly reflects the pairing of electrons. In the copper-oxide high-temperature superconductors (HTSCs), a strongly anisotropic energy gap, which vanishes along high-symmetry directions, is a clear manifestation of the d-wave symmetry of the pairing. There is, however, a dramatic change in the form of the gap anisotropy with reduced carrier concentration (underdoping). Although the vanishing of the gap along the diagonal to the square Cu-O bond directions is robust, the doping dependence of the large gap along the Cu-O directions suggests that its origin might be different from pairing. It is thus tempting to associate the large gap with a second-order parameter distinct from superconductivity. We use angle-resolved photoemission spectroscopy to show that the two-gap behavior and the destruction of well-defined electronic excitations are not universal features of HTSCs, and depend sensitively on how the underdoped materials are prepared. Depending on cation substitution, underdoped samples either show two-gap behavior or not. In contrast, many other characteristics of HTSCs, such as the dome-like dependence of on doping, long-lived excitations along the diagonals to the Cu-O bonds, and an energy gap at the Brillouin zone boundary that decreases monotonically with doping while persisting above (the pseudogap), are present in all samples, irrespective of whether they exhibit two-gap behavior or not. Our results imply that universal aspects of high- superconductivity are relatively insensitive to differences in the electronic states along the Cu-O bond directions. PMID:24101464

Zhao, Junjing; Chatterjee, Utpal; Ai, Dingfei; Hinks, David G; Zheng, Hong; Gu, G D; Castellan, John-Paul; Rosenkranz, Stephan; Claus, Helmut; Norman, Michael R; Randeria, Mohit; Campuzano, Juan Carlos

2013-10-29

197

Etching of Silicon in HBr Plasmas for High Aspect Ratio Features  

NASA Technical Reports Server (NTRS)

Etching in semiconductor processing typically involves using halides because of the relatively fast rates. Bromine containing plasmas can generate high aspect ratio trenches, desirable for DRAM and MEMS applications, with relatively straight sidewalk We present scanning electron microscope images for silicon-etched trenches in a HBr plasma. Using a feature profile simulation, we show that the removal yield parameter, or number of neutrals removed per incident ion due to all processes (sputtering, spontaneous desorption, etc.), dictates the profile shape. We find that the profile becomes pinched off when the removal yield is a constant, with a maximum aspect ratio (AR) of about 5 to 1 (depth to height). When the removal yield decreases with increasing ion angle, the etch rate increases at the comers and the trench bottom broadens. The profiles have ARs of over 9:1 for yields that vary with ion angle. To match the experimentally observed etched time of 250 s for an AR of 9:1 with a trench width of 0.135 microns, we find that the neutral flux must be 3.336 x 10(exp 17)sq cm/s.

Hwang, Helen H.; Meyyappan, M.; Mathad, G. S.; Ranade, R.

2002-01-01

198

Special features of a substorm during high solar wind dynamic pressure  

SciTech Connect

A substorm on July 24, 1986, exhibiting a rather unusual auroral morphology is analyzed with data from spacecraft (Viking; DMSP F6 and F7; GOES 5 and 6; three LANL geosynchronous satellites; CCE; and IMP 8). This substorm occurred during high solar wind dynamic pressure (>5 nPa). Several notable features for this substorm are: (1) the substorm onset activity was preceded by prominent auroral activations in the morning sector with spatial separations between adjacent bright regions ranging from {approximately}160 to 640 km, and their intensity was modulated at {approximately}3.2-min intervals; (2) the initial substorm activity was concentrated in the morning sector, followed by a sudden activation in the dusk sector, leaving the midnight sector relatively undisturbed, in sharp contrast to the traditional substorm development; (3) while a substorm injection was observed at a geocentric distance of {approximately}8.4 R{sub E} by CCE in association with the substorm onset, particle injections (detectable with three LANL geosynchronous satellites) and dipolarization signatures (detectable by the two GOES satellites) were not observed until subsequent intensifications; (4) timing subsequent substorm intensifications from injections at the geosynchronous altitude differed from timing intensifications based on Viking auroral images by as much as {approximately}3 min; (5) the polar cap boundary was at a significantly higher latitude than the poleward boundary delineated by detectable auroral luminosity in the auroral oval. Detailed timing analysis suggests the substorm onset to be associated with southward interplanetary magnetic field (IMF), possibly with the crossing of an IMF sector boundary (interplanetary current sheet). The dimming of auroral luminosity in the midnight region was associated with a sudden northward turning of the IMF during high solar wind dynamic pressure condition. 36 refs., 14 figs.

Lui, A.T.Y.; Ohtani, S.; Newell, P.T. [Johns Hopkins Univ., Laurel, MD (United States)] [and others] [Johns Hopkins Univ., Laurel, MD (United States); and others

1995-10-01

199

Mitotic Phosphorylation of Chromosomal Protein HMGN1 Inhibits Nuclear Import and Promotes Interaction with 14.3.3 Proteins  

PubMed Central

Progression through mitosis is associated with reversible phosphorylation of many nuclear proteins including that of the high-mobility group N (HMGN) nucleosomal binding protein family. Here we use immunofluorescence and in vitro nuclear import studies to demonstrate that mitotic phosphorylation of the nucleosomal binding domain (NBD) of the HMGN1 protein prevents its reentry into the newly formed nucleus in late telophase. By microinjecting wild-type and mutant proteins into the cytoplasm of HeLa cells and expressing these proteins in HmgN1?/? cells, we demonstrate that the inability to enter the nucleus is a consequence of phosphorylation and is not due to the presence of negative charges. Using affinity chromatography with recombinant proteins and nuclear extracts prepared from logarithmically growing or mitotically arrested cells, we demonstrate that phosphorylation of the NBD of HMGN1 promotes interaction with specific 14.3.3 isotypes. We conclude that mitotic phosphorylation of HMGN1 protein promotes interaction with 14.3.3 proteins and suggest that this interaction impedes the reentry of the proteins into the nucleus during telophase. Taken together with the results of previous studies, our results suggest a dual role for mitotic phosphorylation of HMGN1: abolishment of chromatin binding and inhibition of nuclear import.

Prymakowska-Bosak, Marta; Hock, Robert; Catez, Frederic; Lim, Jae-Hwan; Birger, Yehudit; Shirakawa, Hitoshi; Lee, Kyung; Bustin, Michael

2002-01-01

200

Microdevice having interior cavity with high aspect ratio surface features and associated methods of manufacture and use  

DOEpatents

A microdevice having interior cavity with high aspect ratio features and ultrasmooth surfaces, and associated method of manufacture and use is described. An LIGA-produced shaped bit is used to contour polish the surface of a sacrificial mandrel. The contoured sacrificial mandrel is subsequently coated with a structural material and the mandrel removed to produce microdevices having micrometer-sized surface features and sub-micrometer RMS surface roughness.

Morales, Alfredo M. (Pleasanton, CA) [Pleasanton, CA

2002-01-01

201

Evaluation of Precipitation Features in High-Frequency SSM\\/I Measurements Over Indian Land and Oceanic Regions  

Microsoft Academic Search

Evaluation of the Special Sensor Microwave Imager (SSM\\/I) precipitation features is presented from various passes over Indian oceanic and land regions under the framework of radiative transfer simulations for both emission and scattering atmospheres. There is considerable uncertainty in the interpretation of the SSM\\/I high-frequency scattering features for development of rainfall algorithms. Specifically large areas of very low emissivity regimes

Rajesh Kumar; Rakesh Mohan Gairola; Anoop Mishra; Atul Kumar Varma; Indra Mohan Lal Das

2009-01-01

202

Robustness of features for automatic target discrimination in high-resolution polarimetric SAR data  

NASA Astrophysics Data System (ADS)

We have studied the robustness of features against aspect variability for the purpose of target discrimination using polarimetric 35 Ghz ISAR data. Images at a resolution of 10 cm and 30 cm have been used for a complete aspect range of 360 degrees. The data covered four military targets: T72, ZSU23/4, T62, and BMP2. For the study we composed several feature vectors out of individual features extracted from the images. The features are divided into three categories: radiometric, geometric and polarimetric. We found that individual features show a strong variability as a function of aspect angle and cannot be used to discriminate between the targets irrespectively of the aspect angle. Using feature vectors and a maximum likelihood classifier reasonable discrimination (about 80%) between the four targets irrespective of the aspect angle was obtained at 10 cm resolution. At 30 cm resolution less significant discrimination (less than 70%) was found irrespective of the kind of feature vector used. In addition we investigated target discrimination per 30-degree aspect interval. In order to determine the aspect angle of targets we used a technique based on the Radon transformation, which gave an accuracy of about 5 degrees in aspect angle. We found that in this case good discrimination (more than 90%) was obtained at 10 cm resolution and reasonable discrimination (about 80%) at 30 cm resolution. The results are compared with analogous results from MSTAR data (30 cm resolution) of comparable targets.

van den Broek, Albertus C.; Dekker, Rob J.; Steeghs, Phillippe

2003-09-01

203

An improved high order texture features extraction method with application to pathological diagnosis of colon lesions for CT colonography  

NASA Astrophysics Data System (ADS)

Differentiation of colon lesions according to underlying pathology, e.g., neoplastic and non-neoplastic, is of fundamental importance for patient management. Image intensity based textural features have been recognized as a useful biomarker for the differentiation task. In this paper, we introduce high order texture features, beyond the intensity, such as gradient and curvature, for that task. Based on the Haralick texture analysis method, we introduce a virtual pathological method to explore the utility of texture features from high order differentiations, i.e., gradient and curvature, of the image intensity distribution. The texture features were validated on database consisting of 148 colon lesions, of which 35 are non-neoplastic lesions, using the random forest classifier and the merit of area under the curve (AUC) of the receiver operating characteristics. The results show that after applying the high order features, the AUC was improved from 0.8069 to 0.8544 in differentiating non-neoplastic lesion from neoplastic ones, e.g., hyperplastic polyps from tubular adenomas, tubulovillous adenomas and adenocarcinomas. The experimental results demonstrated that texture features from the higher order images can significantly improve the classification accuracy in pathological differentiation of colorectal lesions. The gain in differentiation capability shall increase the potential of computed tomography (CT) colonography for colorectal cancer screening by not only detecting polyps but also classifying them from optimal polyp management for the best outcome in personalized medicine.

Song, Bowen; Zhang, Guopeng; Lu, Hongbing; Wang, Huafeng; Han, Fangfang; Zhu, Wei; Liang, Zhengrong

2014-03-01

204

Rab11 endosomes contribute to mitotic spindle organization and orientation.  

PubMed

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 ?-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 ?-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

Hehnly, Heidi; Doxsey, Stephen

2014-03-10

205

Use of N-Acetylcolchamine as a Mitotic Poison.  

National Technical Information Service (NTIS)

The anti-mitotic activity of N-acetylcolchamine on Ehrlich ascites cancer cells has been studied in vivo in mice. It has been established that N-acetylcolchamine is an inhibitor of mitosis which, like colchicine, is able to block cell division at the stag...

V. I. Khmelevskii F. Y. Zusman O. V. Khmelevskii N. N. Myshkin

1969-01-01

206

Adhesion signaling by a novel mitotic substrate of src kinases  

PubMed Central

Abstract/Summary Src kinases are activated and relocalize to the cytoplasm during mitosis, but their mitotic function has remained elusive. We describe here a novel mitotic substrate of src kinases. Trask (Transmembrane and Associated with Src Kinases) is a 140kd type I transmembrane glycoprotein unrelated to currently known protein families. Src kinases phosphorylate Trask in vitro and mediate its mitotic hyperphosphorylation in vivo. Trask associates with both yes and src, is localized to the cell membrane during interphase, and undergoes cytoplasmic relocalization during mitosis. Overexpression of Trask leads to cell rounding and a loss of adhesion phenotype. Consistent with a function in cell adhesion, Trask interacts with a number of adhesion and matrix proteins including cadherins, syndecans, and the membrane-type serine protease 1 (MT-SP1), and is proteolytically cleaved by MT-SP1. Trask is unique among cell adhesion molecules in that it is under cell cycle regulation and thus links src kinases with the mitotic regulation of cell adhesion. This suggests a potential pathway by which hyperactive src kinases in tumors can deregulate adhesion signaling and mediate the metastatic phenotype.

Bhatt, Ami S.; Erdjument-Bromage, Hediye; Tempst, Paul; Craik, Charles S.; Moasser, Mark M.

2011-01-01

207

Tumor suppressor VHL functions in the control of mitotic fidelity.  

PubMed

The von Hippel-Lindau (VHL) tumor suppressor protein pVHL is commonly mutated in clear cell renal cell carcinoma (ccRCC) and has been implicated in the control of multiple cellular processes that might be linked to tumor suppression, including promoting proper spindle orientation and chromosomal stability. However, it is unclear whether pVHL exerts these mitotic regulatory functions in vivo as well. Here, we applied ischemic kidney injury to stimulate cell division in otherwise quiescent mouse adult kidneys. We show that in the short term (5.5 days after surgery), Vhl-deficient kidney cells demonstrate both spindle misorientation and aneuploidy. The spindle misorientation phenotype encompassed changes in directed cell division, which may manifest in the development of cystic lesions, whereas the aneuploidy phenotype involved the occurrence of lagging chromosomes but not chromosome bridges, indicative of mitotic checkpoint impairment. Intriguingly, in the long term (4 months after the ischemic insult), Vhl-deficient kidneys displayed a heterogeneous pattern of ccRCC precursor lesions, including cysts, clear cell-type cells, and dysplasia. Together, these data provide direct evidence for a key role of pVHL in mediating oriented cell division and faithful mitotic checkpoint function in the renal epithelium, emphasizing the importance of pVHL as a controller of mitotic fidelity in vivo. PMID:24362914

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

2014-05-01

208

The Distribution of Active Force Generators Controls Mitotic Spindle Position  

Microsoft Academic Search

During unequal cell divisions a mitotic spindle is eccentrically positioned before cell cleavage. To determine the basis of the net force imbalance that causes spindle displacement in one-cell Caenorhabditis elegans embryos, we fragmented centrosomes with an ultraviolet laser. Analysis of the mean and variance of fragment speeds suggests that the force imbalance is due to a larger number of force

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

2003-01-01

209

A mitotic transcriptional switch in polycystic kidney disease  

PubMed Central

Hepatocyte nuclear factor-1?(HNF-1?) is a transcription factor required for the expression of several renal cystic genes and whose prenatal deletion leads to polycystic kidney disease (PKD)1. We show here that inactivation of Hnf1b from postnatal day 10 onward does not elicit cystic dilations in tubules after their proliferative morphogenetic elongation is over. Cystogenic resistance is intrinsically linked to the quiescent state of cells. In fact, when Hnf1b deficient quiescent cells are forced to proliferate by an ischemiareperfusion injury, they give rise to cysts, owing to loss of oriented cell division. Remarkably, in quiescent cells, the transcription of crucial cystogenic target genes is maintained even in the absence of HNF-1?. However, their expression is lost as soon as cells proliferate and the chromatin of target genes acquires heterochromatin marks. These results unveil a previously undescribed aspect of gene regulation. It is well established that transcription is shut off during the mitotic condensation of chromatin2,3. We propose that transcription factors such as HNF-1? might be involved in reprogramming gene expression after transcriptional silencing is induced by mitotic chromatin condensation. Notably, HNF-1? remains associated with the mitotically condensed chromosomal barrels. This association suggests that HNF-1? is a bookmarking factor that is necessary for reopening the chromatin of target genes after mitotic silencing.

Verdeguer, Francisco; Corre, Stephanie Le; Fischer, Evelyne; Callens, Celine; Garbay, Serge; Doyen, Antonia; Igarashi, Peter; Terzi, Fabiola; Pontoglio, Marco

2011-01-01

210

Polarimetric contrast enhancement coefficients for perfecting high-resolution POL-SAR/SAL image feature extraction  

NASA Astrophysics Data System (ADS)

In microwave remote sensing, it is desirable to select radar antenna polarizations that maximize the contrast between two classes of scatterers or scatterer ensembles. A polarimetric radar measures complete polarization properties of a target and then provides a vector description of the resulting scattered wave through various target matrices. Several optimization procedures for the completely and partially polarized cases have been proposed based on the theory of radar polarimetry. It is the purpose of this paper to present optimization procedures for the enhancement of polarimetric contrast between two time-varying targets and to extend the procedure to two spatially incoherent image pixel targets. The targets are now characterized by the time-averaged or spatially-averaged Kronecker matrices, from which one can obtain the associated Graves and Kennaugh matrices. The Graves matrices of the targets are used to find a transmitter polarization to maximize the ratio of scattered power densities at the receiver. Using the Lagrange multiplier method, the maximization problem is cast into the form of a generalized Balois eigenvalue equation. The largest eigenvalue of the equation equals the maximal power ratio, and the optimal effective length of the transmitting antenna is proportional to the corresponding eigenvector. The Kennaugh matrices of the targets are employed to obtain the Kennaugh vectors of partially polarized scattered waves from the two targets. Each of the scattered Kennaugh vectors is decomposed into a completely polarized and an unpolarized part. It is well known that the power received from the unpolarized part is independent of the polarization characteristics of the receiving antenna. Then a receiver polarization is selected to maximize or minimize the completely polarized part scattered from the desired or the undesired target. As a numerical example, the optimal Stokes vectors of transmitting and receiving antennas are given to show the validity of the optimization procedures and how it can be applied to perfecting high resolution POL-SAR/SAL Image Feature Extraction.

Mott, Harold; Boerner, Wolfgang-Martin

1997-12-01

211

Listeria bacteriophage peptidoglycan hydrolases feature high thermoresistance and reveal increased activity after divalent metal cation substitution.  

PubMed

The ability of the bacteriophage-encoded peptidoglycan hydrolases (endolysins) to destroy Gram-positive bacteria from without makes these enzymes promising antimicrobials. Recombinant endolysins from Listeria monocytogenes phages have been shown to rapidly lyse and kill the pathogen in all environments. To determine optimum conditions regarding application of recombinant Listeria phage endolysins in food or production equipments, properties of different Listeria endolysins were studied. Optimum NaCl concentration for the amidase HPL511 was 200 nM and 300 mM for the peptidases HPL118, HPL500, and HPLP35. Unlike most other peptidoglycan hydrolases, all four enzymes exhibited highest activity at elevated pH values at around pH 8-9. Lytic activity was abolished by EDTA and could be restored by supplementation with various divalent metal cations, indicating their role in catalytic function. While substitution of the native Zn(2+) by Ca(2+) or Mn(2+) was most effective in case of HPL118, HPL500, and HPLP35, supplementation with Co(2+) and Mn(2+) resulted in an approximately 5-fold increase in HPL511 activity. Interestingly, the glutamate peptidases feature a conserved SxHxxGxAxD zinc-binding motif, which is not present in the amidases, although they also require centrally located divalent metals for activity. The endolysins HPL118, HPL511, and HPLP35 revealed a surprisingly high thermostability, with up to 35% activity remaining after 30 min incubation at 90°C. The available data suggest that denaturation at elevated temperatures is reversible and may be followed by rapid refolding into a functional state. PMID:21720825

Schmelcher, Mathias; Waldherr, Florian; Loessner, Martin J

2012-01-01

212

High-density haplotyping with microarray-based expression and single feature polymorphism markers in Arabidopsis  

PubMed Central

Expression microarrays hybridized with RNA can simultaneously provide both phenotypic (gene expression) and genotypic (marker) data. We developed two types of genetic markers from Affymetrix GeneChip expression data to generate detailed haplotypes for 148 recombinant inbred lines (RILs) derived from Arabidopsis thaliana accessions Bayreuth and Shahdara. Gene expression markers (GEMs) are based on differences in transcript levels that exhibit bimodal distributions in segregating progeny, while single feature polymorphism (SFP) markers rely on differences in hybridization to individual oligonucleotide probes. Unlike SFPs, GEMs can be derived from any type of DNA-based expression microarray. Our method identifies SFPs independent of a gene’s expression level. Alleles for each GEM and SFP marker were ascertained with GeneChip data from parental accessions as well as RILs; a novel algorithm for allele determination using RIL distributions capitalized on the high level of genetic replication per locus. GEMs and SFP markers provided robust markers in 187 and 968 genes, respectively, which allowed estimation of gene order consistent with that predicted from the Col-0 genomic sequence. Using microarrays on a population to simultaneously measure gene expression variation and obtain genotypic data for a linkage map will facilitate expression QTL analyses without the need for separate genotyping. We have demonstrated that gene expression measurements from microarrays can be leveraged to identify polymorphisms across the genome and can be efficiently developed into genetic markers that are verifiable in a large segregating RIL population. Both marker types also offer opportunities for massively parallel mapping in unsequenced and less studied species.

West, Marilyn A.L.; van Leeuwen, Hans; Kozik, Alexander; Kliebenstein, Daniel J.; Doerge, R.W.; St. Clair, Dina A.; Michelmore, Richard W.

2006-01-01

213

Static features in real-time recognition of isolated vowels at high pitch.  

PubMed

This paper addresses the problem of automatic identification of vowels uttered in isolation by female and child speakers. In this case, the magnitude spectrum of voiced vowels is sparsely sampled since only frequencies at integer multiples of F0 are significant. This impacts negatively on the performance of vowel identification techniques that either ignore pitch or rely on global shape models. A new pitch-dependent approach to vowel identification is proposed that emerges from the concept of timbre and that defines perceptual spectral clusters (PSC) of harmonic partials. A representative set of static PSC-related features are estimated and their performance is evaluated in automatic classification tests using the Mahalanobis distance. Linear prediction features and Mel-frequency cepstral coefficients (MFCC) coefficients are used as a reference and a database of five (Portuguese) natural vowel sounds uttered by 44 speakers (including 27 child speakers) is used for training and testing the Gaussian models. Results indicate that perceptual spectral cluster (PSC) features perform better than plain linear prediction features, but perform slightly worse than MFCC features. However, PSC features have the potential to take full advantage of the pitch structure of voiced vowels, namely in the analysis of concurrent voices, or by using pitch as a normalization parameter. PMID:17902873

Ferreira, Aníbal J S

2007-10-01

214

Mitotic regulation of fungal cell-to-cell connectivity through septal pores involves the NIMA kinase  

PubMed Central

Intercellular bridges are a conserved feature of multicellular organisms. In multicellular fungi, cells are connected directly via intercellular bridges called septal pores. Using Aspergillus nidulans, we demonstrate for the first time that septal pores are regulated to be opened during interphase but closed during mitosis. Septal pore–associated proteins display dynamic cell cycle–regulated locations at mature septa. Of importance, the mitotic NIMA kinase locates to forming septa and surprisingly then remains at septa throughout interphase. However, during mitosis, when NIMA transiently locates to nuclei to promote mitosis, its levels at septa drop. A model is proposed in which NIMA helps keep septal pores open during interphase and then closed when it is removed from them during mitosis. In support of this hypothesis, NIMA inactivation is shown to promote interphase septal pore closing. Because NIMA triggers nuclear pore complex opening during mitosis, our findings suggest that common cell cycle regulatory mechanisms might control septal pores and nuclear pores such that they are opened and closed out of phase to each other during cell cycle progression. The study provides insights into how and why cytoplasmically connected Aspergillus cells maintain mitotic autonomy.

Shen, Kuo-Fang; Osmani, Aysha H.; Govindaraghavan, Meera; Osmani, Stephen A.

2014-01-01

215

Comparison of Aerosol Classification from Airborne High Spectral Resolution Lidar and the CALIPSO Vertical Feature Mask  

NASA Astrophysics Data System (ADS)

The NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL-1) on the NASA B200 aircraft has acquired large datasets of aerosol extinction (532nm), backscatter (532 and 1064nm), and depolarization (532 and 1064nm) profiles during 349 science flights in 19 field missions across North America since 2006. The extinction-to-backscatter ratio ("lidar ratio"), aerosol depolarization ratios, and backscatter color ratio measurements from HSRL-1 are scale-invariant parameters that depend on aerosol type but not concentration. These four aerosol intensive parameters are combined to qualitatively classify HSRL aerosol measurements into eight separate composition types. The classification methodology uses models formed from "training cases" with known aerosol type. The remaining measurements are then compared with these models using the Mahalanobis distance. Aerosol products from the CALIPSO satellite include aerosol type information as well, which is used as input to the CALIPSO aerosol retrieval. CALIPSO aerosol types are inferred using a mix of aerosol loading-dependent parameters, estimated aerosol depolarization, and location, altitude, and surface type information. The HSRL instrument flies beneath the CALIPSO satellite orbit track, presenting the opportunity for comparisons between the HSRL aerosol typing and the CALIPSO Vertical Feature Mask Aerosol Subtype product, giving insight into the performance of the CALIPSO aerosol type algorithm. We find that the aerosol classification from the two instruments frequently agree for marine aerosols and pure dust, and somewhat less frequently for pollution and smoke. In addition, the comparison suggests that the CALIPSO polluted dust type is overly inclusive, encompassing cases of dust combined with marine aerosol as well as cases without much evidence of dust. Qualitative classification of aerosol type combined with quantitative profile measurements of aerosol backscatter and extinction has many useful applications. The HSRL products are used to apportion AOT by type and vertical location in the column, and to characterize the frequency of cases where multiple types are present in the column. Resolving scenes with multiple types in the column is not possible with passive imaging radiometer and polarimeter measurements. The HSRL aerosol type also has higher resolution than the CALIPSO layer-wise product and provides insight into the performance of CALIPSO layer separation. Information about the vertical distribution of aerosol types is useful for estimating radiative forcing, understanding aerosol lifetime and transport, and assessing the predictions of transport models. CALIPSO has been a pathfinder, providing the first long-term global data set of aerosol vertical distribution. Based on our results, a future satellite lidar similar to CALIPSO, but with the addition of polarization sensitivity at 1064 nm and the HSRL technique at 532 nm, could provide a significant advance in characterizing the vertical distribution of aerosol.

Burton, S. P.; Ferrare, R. A.; Omar, A. H.; Hostetler, C. A.; Hair, J. W.; Rogers, R.; Obland, M. D.; Butler, C. F.; Cook, A. L.; Harper, D. B.

2012-12-01

216

The high prevalence of “Soft” bipolar (II) features in atypical depression  

Microsoft Academic Search

Seventy-two percent of 86 major depressive patients with atypical features as defined by the DSM-IV and evaluated systematically were found to meet our criteria for bipolar 11 and related “soft” bipolar disorders; nearly 60% had antecedent cyclothymic or hyperthymic temperaments. The family history for bipolar disorder validated these clinical findings. Even if we limit the diagnosis of bipolar II to

G Perugi; H. S Akiskal; L Lattanzi; D Cecconi; C Mastrocinque; A Patronelli; S Vignoli; E Bemi

1998-01-01

217

Down-modulation of nucleoporin RanBP2/Nup358 impaired chromosomal alignment and induced mitotic catastrophe  

PubMed Central

Chromosomal missegregation is a common feature of many human tumors. Recent studies have indicated a link between nucleoporin RanBP2/Nup358 and chromosomal segregation during mitosis; however, the molecular details have yet to be fully established. Observed through live cell imaging and flow cytometry, here we show that RNA interference-mediated knockdown of RanBP2 induced G2/M phase arrest, metaphase catastrophe and mitotic cell death. Furthermore, RanBP2 down-modulation disrupted importin/karyopherin ?1 as well as the expression and localization of the Ran GTPase activating protein 1. We found that N-terminal of RanBP2 interacted with the N-terminal of importin ?1. Moreover, at least a portion of RanBP2 partially localizes at the centrosome during mitosis. Notably, we also found that GTPase Ran is also involved in the regulation of RanBP2–importin ?1 interaction. Overall, our results suggest that mitotic arrest and the following cell death were caused by depletion of RanBP2. Our findings point to a crucial role for RanBP2 in proper mitotic progression and faithful chromosomal segregation.

Hashizume, C; Kobayashi, A; Wong, R W

2013-01-01

218

Tumor Environmental Factors Glucose Deprivation and Lactic Acidosis Induce Mitotic Chromosomal Instability - An Implication in Aneuploid Human Tumors  

PubMed Central

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.

Zhu, Chunpeng; Hu, Xun

2013-01-01

219

High cadence spectropolarimetry of moving magnetic features observed around a pore  

NASA Astrophysics Data System (ADS)

Context. Moving magnetic features (MMFs) are small-size magnetic elements that are seen to stream out from sunspots, generally during their decay phase. Several observational results presented in the literature suggest them to be closely related to magnetic filaments that extend from the penumbra of the parent spot. Nevertheless, few observations of MMFs streaming out from spots without penumbra have been reported. The literature still lacks analyses of the physical properties of these features. Aims: We investigate physical properties of monopolar MMFs observed around a small pore that had developed penumbra in the days preceding our observations and compare our results with those reported in the literature for features observed around sunspots. Methods: We analyzed NOAA 11005 during its decay phase with data acquired at the Dunn Solar Telescope in the Fe i 617.3 nm and the Ca ii 854.2 nm spectral lines with IBIS, and in the G-band. The field of view showed monopolar MMFs of both polarities streaming out from the leading negative polarity pore of the observed active region. Combining different analyses of the data, we investigated the temporal evolution of the relevant physical quantities associated with the MMFs as well as the photospheric and chromospheric signatures of these features. Results: We show that the characteristics of the investigated MMFs agree with those reported in the literature for MMFs that stream out from spots with penumbrae. Moreover, observations of at least two of the observed features suggest them to be manifestations of emerging magnetic arches. Appendices A and B, and a movie are available in electronic form at http://www.aanda.org

Criscuoli, S.; Del Moro, D.; Giannattasio, F.; Viticchié, B.; Giorgi, F.; Ermolli, I.; Zuccarello, F.; Berrilli, F.

2012-10-01

220

Callous-Unemotional Features, Behavioral Inhibition, and Parenting: Independent Predictors of Aggression in a High-Risk Preschool Sample  

ERIC Educational Resources Information Center

A behaviorally-uninhibited temperament, callous-unemotional (CU) features, and harsh parenting have been associated with specific patterns of aggressive behavior in older children and adolescents. We tested the additive and interactive effects of these factors in predicting different types of aggressive behavior in a high-risk preschool sample.…

Kimonis, Eva R.; Frick, Paul J.; Boris, Neil W.; Smyke, Anna T.; Cornell, Amy H.; Farrell, Jamie M.; Zeanah, Charles H.

2006-01-01

221

A Mitotic Kinase TOPK Enhances Cdk1\\/cyclin B1-dependent Phosphorylation of PRC1 and Promotes Cytokinesis  

Microsoft Academic Search

A MAPKK-like mitotic kinase, TOPK, implies the formation of mitotic spindles and spindle midzone and accomplishing cytokinesis, however, its underlying mechanism remains unclear. A microtubule bundling protein, PRC1, plays a pivotal role in the formation of mitotic spindles and spindle midzone. Because of their functional resemblance, we attempted to clarify the links between these two molecules. TOPK supported mitotic advance

Yasuhito Abe; Takashi Takeuchi; Lisa Kagawa-Miki; Norifumi Ueda; Kazuhiro Shigemoto; Masaki Yasukawa; Katsumi Kito

2007-01-01

222

Dynein-like Mg2+-ATPase in mitotic spindles isolated from sea urchin embryos (Strongylocentrotus droebachiensis).  

PubMed

Two distinctly different ATPases have been reported to be endogenous to the mitotic apparatus: a Mg2+-ATPase resembling axonemal dynein, and a Ca2+-ATPase postulated to be bound in membranes. To examine the nature of the Mg2+-ATPase, we isolated membrane-free mitotic spindles from Stronglylocentrotus droebachiensis embryos by rapidly lysing these in a calcium-chelating, low-ionic-strength buffer (5 mM EGTA, 0.5 mM MgCl2, 10 mM PIPES, pH 6.8) that contained 1% Nonidet P-40. The fibrous isolated mitotic spindles closely resembled spindles in living cells, both in general morphology and in birefringence. In electron micrographs, the spindles were composed primarily of microtubules, free from membranes and highly extracted of intermicrotubular cytoplasmic ground substance. As analyzed by SDS-polyacrylamide gel electrophoresis (SDS-PAGE), the pelleted spindles contain 18% tubulin, variable amounts of actin (2-8%), and an unidentified protein of 55 kdaltons in a constant weight ratio to tubulin (1:2.5). The isolated spindles also contained two polypeptides, larger than 300 kdaltons, that comigrated with egg dynein polypeptides, and ATPase activity (0.02 mumol Pi/mg . min) that closely resembled both flagellar and egg dynein. The spindle Mg2+-ATPase showed a ratio of Ca2+-/Mg2+-ATPase = 0.85, had minimal activity in KCl and EDTA, and cleaved GTP at 35% of the rate of ATP. The Mg2+-ATPase was insensitive to ouabain or oligomycin. The spindle Mg2+-ATPase was inhibited by sodium vanadate but, like egg dynein, was less sensitive to vanadate than flagellar dynein. The spindle Mg2+-ATPase does not resemble the mitotic Ca2+-ATPase described by others. We propose that the spindle Mg2+-ATPase is egg dynein. Bound carbohydrate on the two high-molecular-weight polypeptides of both egg dynein and the spindle enzyme suggest that these proteins may normally associate with membranes in the living cell. PMID:6447705

Pratt, M M; Otter, T; Salmon, E D

1980-09-01

223

Formation of coastline features by large-scale instabilities induced by high-angle waves.  

PubMed

Along shore sediment transport that is driven by waves is generally assumed to smooth a coastline. This assumption is valid for small angles between the wave crest lines and the shore, as has been demonstrated in shoreline models. But when the angle between the waves and the shoreline is sufficiently large, small perturbations to a straight shoreline will grow. Here we use a numerical model to investigate the implications of this instability mechanism for large-scale morphology over long timescales. Our simulations show growth of coastline perturbations that interact with each other to produce large-scale features that resemble various kinds of natural landforms, including the capes and cuspate forelands observed along the Carolina coast of southeastern North America. Wind and wave data from this area support our hypothesis that such an instability mechanism could be responsible for the formation of shoreline features at spatial scales up to hundreds of kilometres and temporal scales up to millennia. PMID:11713526

Ashton, A; Murray, A B; Arnault, O

2001-11-15

224

Mitotic regulation of a TATA-binding-protein-containing complex.  

PubMed Central

The mitotic state is associated with a generalized repression of transcription. We show that mitotic repression of RNA polymerase III transcription can be reproduced by using extracts of synchronized HeLa cells. We have used this system to investigate the molecular basis of transcriptional repression during mitosis. We find a specific decrease in the activity of the TATA-binding-protein (TBP)-containing complex TFIIIB. TBP itself is hyperphosphorylated at mitosis, but this does not appear to account for the loss of TFIIIB activity. Instead, one or more TBP-associated components appear to be regulated. The data suggest that changes in the activity of TBP-associated components contribute to the coordinate repression of gene expression that occurs at mitosis.

White, R J; Gottlieb, T M; Downes, C S; Jackson, S P

1995-01-01

225

Molecular pathways regulating mitotic spindle orientation in animal cells  

PubMed Central

Orientation of the cell division axis is essential for the correct development and maintenance of tissue morphology, both for symmetric cell divisions and for the asymmetric distribution of fate determinants during, for example, stem cell divisions. Oriented cell division depends on the positioning of the mitotic spindle relative to an axis of polarity. Recent studies have illuminated an expanding list of spindle orientation regulators, and a molecular model for how cells couple cortical polarity with spindle positioning has begun to emerge. Here, we review both the well-established spindle orientation pathways and recently identified regulators, focusing on how communication between the cell cortex and the spindle is achieved, to provide a contemporary view of how positioning of the mitotic spindle occurs.

Lu, Michelle S.; Johnston, Christopher A.

2013-01-01

226

Control of the mitotic cleavage plane by local epithelial topology  

PubMed Central

SUMMARY For nearly 150 years, it has been recognized that cell shape strongly influences the orientation of the mitotic cleavage plane (e.g. Hofmeister, 1863). However, we still understand little about the complex interplay between cell shape and cleavage plane orientation in epithelia, where polygonal cell geometries emerge from multiple factors, including cell packing, cell growth, and cell division itself. Here, using mechanical simulations, we show that the polygonal shapes of individual cells can systematically bias the long axis orientations of their adjacent mitotic neighbors. Strikingly, analysis of both animal epithelia and plant epidermis confirm a robust and nearly identical correlation between local cell topology and cleavage plane orientation in vivo. Using simple mathematics, we show that this effect derives from fundamental packing constraints. Our results suggest that local epithelial topology is a key determinant of cleavage plane orientation, and that cleavage plane bias may be a widespread property of polygonal cell sheets in plants and animals.

Gibson, William T.; Veldhuis, James H.; Rubinstein, Boris; Cartwright, Heather N.; Perrimon, Norbert; Brodland, G. Wayne; Nagpal, Radhika; Gibson, Matthew C.

2012-01-01

227

The Mitotic Exit Network: new turns on old pathways.  

PubMed

In budding yeast, the Mitotic Exit Network (MEN) is a signaling pathway known to drive cells out of mitosis and promote the faithful division of cells. The MEN triggers inactivation of cyclin-dependent kinase (Cdk1), the master regulator of mitosis, and the onset of cytokinesis after segregation of the daughter nuclei. The current model of the MEN suggests that MEN activity is restricted to late anaphase and coordinated with proper alignment of the spindle pole bodies (SPBs) with the division axis. However, recent evidence suggests that MEN activity may function earlier in mitosis, prompting re-evaluation of the current model. Here we attempt to integrate this recent progress into the current view of mitotic exit. PMID:24594661

Hotz, Manuel; Barral, Yves

2014-03-01

228

Proteins related to the spindle and checkpoint mitotic emphasize the different pathogenesis of hypoplastic MDS.  

PubMed

Some studies show that alterations in expression of proteins related to mitotic spindle (AURORAS KINASE A and B) and mitotic checkpoint (CDC20 and MAD2L1) are involved in chromosomal instability and tumor progression in various solid and hematologic malignancies. This study aimed to evaluate these genes in MDS patients. The cytogenetics analysis was carried out by G-banding, AURKA and AURKB amplification was performed using FISH, and AURKA, AURKB, CDC20 and MAD2L1 gene expression was performed by qRT-PCR in 61 samples of bone marrow from MDS patients. AURKA gene amplification was observed in 10% of the cases, which also showed higher expression levels than the control group (p=0.038). Patients with normo/hypercellular BM presented significantly higher expression levels than hypocellular BM patients, but normo and hypercellular BM groups did not differ. After logistic regression analysis, our results showed that HIGH expression levels were associated with increased risk of developing normo/hypercellular MDS. It also indicated that age is associated with AURKA, CDC20 and MAD2L1 HIGH expression levels. The distinct expression of hypocellular patients emphasizes the prognostic importance of cellularity to MDS. The amplification/high expression of AURKA suggests that the increased expression of this gene may be related to the pathogenesis of disease. PMID:24314588

Heredia, Fabiola Fernandes; de Sousa, Juliana Cordeiro; Ribeiro Junior, Howard Lopes; Carvalho, Alex Fiorini; Magalhaes, Silvia Maria Meira; Pinheiro, Ronald Feitosa

2014-02-01

229

Analysis and design of a high power factor, single-stage electronic ballast with dimming feature  

Microsoft Academic Search

The analysis, design and practical consideration of a single-stage electronic ballast with a dimming feature and unity power factor are presented in this paper. The proposed single-stage ballast is the combination of a boost power converter and a half-bridge series-resonant parallel-loaded inverter. The boost semi-stage, working in the discontinuous conduction mode, functions as a power factor corrector and the inverter

T.-F. Wu; M.-C. Chiang; E.-B. Chang

1997-01-01

230

Fiber feature map based landmark initialization for highly deformable DTI registration  

PubMed Central

This paper presents a novel pipeline for the registration of diffusion tensor images (DTI) with large pathological variations to normal controls based on the use of a novel feature map derived from white matter (WM) fiber tracts. The research presented aims towards an atlas based DTI analysis of subjects with considerable brain pathologies such as tumors or hydrocephalus. In this paper, we propose a novel feature map that is robust against variations in WM fiber tract integrity and use these feature maps to determine a landmark correspondence using a 3D point correspondence algorithm. This correspondence drives a deformation field computed using Gaussian radial basis functions(RBF). This field is employed as an initialization to a standard deformable registration method like demons. We present early preliminary results on the registration of a normal control dataset to a dataset with abnormally enlarged lateral ventricles affected by fatal demyelinating Krabbe disease. The results are analyzed based on a regional tensor matching criterion and a visual assessment of overlap of major WM fiber tracts. While further evaluation and improvements are necessary, the results presented in this paper highlight the potential of our method in handling registration of subjects with severe WM pathology.

Gupta, Aditya; Toews, Matthew; Janardhana, Ravikiran; Rathi, Yogesh; Gilmore, John; Escolar, Maria; Styner, Martin

2013-01-01

231

Unilateral hypoplastic kidney - a novel highly penetrant feature of familial juvenile hyperuricaemic nephropathy  

PubMed Central

Background Familial juvenile hyperuricaemic nephropathy is a rare inherited nephropathy with genetic heterogeneity. Categorised by genetic defect, mutations in uromodulin (UMOD), renin (REN) and hepatocyte nuclear factor-1? (HNF-1?) genes as well as linkage to chromosome 2p22.1-21 have previously been identified. Knowledge of the genetics of this phenotype has provided important clues to developmental pathways in the kidney. Case presentation We report a novel phenotype, with the typical features of hyperuricemia and renal deterioration, but with the additional unexpected feature of unilateral renal hypoplasia. Mutation analyses of the existing known genes and genetic loci were negative indicating a new monogenic cause. Interestingly two cousins of the index case did not share the latter feature, suggesting a modifier gene effect. Conclusion Unilateral renal hypo/aplasia is usually sporadic and relatively common, with no genetic cause to date identified. This reported pedigree reveals the possibility that a new, unknown renal developmental gene may be implicated in the FJHN phenotype.

2014-01-01

232

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

NASA Astrophysics Data System (ADS)

Breast cancer (BCa) grading plays an important role in predicting disease aggressiveness and patient outcome. A key component of BCa grade is mitotic count, which involves quantifying the number of cells in the process of dividing (i.e. undergoing mitosis) at a specific point in time. Currently mitosis counting is done manually by a pathologist looking at multiple high power fields on a glass slide under a microscope, an extremely laborious and time consuming process. The development of computerized systems for automated detection of mitotic nuclei, while highly desirable, is confounded by the highly variable shape and appearance of mitoses. Existing methods use either handcrafted features that capture certain morphological, statistical or textural attributes of mitoses or features learned with convolutional neural networks (CNN). While handcrafted features are inspired by the domain and the particular application, the data-driven CNN models tend to be domain agnostic and attempt to learn additional feature bases that cannot be represented through any of the handcrafted features. On the other hand, CNN is computationally more complex and needs a large number of labeled training instances. Since handcrafted features attempt to model domain pertinent attributes and CNN approaches are largely unsupervised feature generation methods, there is an appeal to attempting to combine these two distinct classes of feature generation strategies to create an integrated set of attributes that can potentially outperform either class of feature extraction strategies individually. In this paper, we present a cascaded approach for mitosis detection that intelligently combines a CNN model and handcrafted features (morphology, color and texture features). By employing a light CNN model, the proposed approach is far less demanding computationally, and the cascaded strategy of combining handcrafted features and CNN-derived features enables the possibility of maximizing performance by leveraging the disconnected feature sets. Evaluation on the public ICPR12 mitosis dataset that has 226 mitoses annotated on 35 High Power Fields (HPF, x400 magnification) by several pathologists and 15 testing HPFs yielded an F-measure of 0.7345. Apart from this being the second best performance ever recorded for this MITOS dataset, our approach is faster and requires fewer computing resources compared to extant methods, making this feasible for clinical use.

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

2014-03-01

233

Mitotic clonal expansion: A synchronous process required for adipogenesis  

Microsoft Academic Search

When induced to differentiate, growth-arrested 3T3-L1 preadipocytes synchronously reenter the cell cycle and undergo mitotic clonal expansion (MCE) followed by expression of genes that produce the adipocyte phenotype. The preadipocytes traverse the G1\\/S checkpoint synchronously as evidenced by the expression\\/activation of cdk2-cyclin-E\\/A, turnover of p27\\/kip1, hyperphosphorylation of Rb, translocation of cyclin D1 from nuclei to cytoplasm and GSK-3 from cytoplasm

Qi-Qun Tang; Tamara C. Otto

2002-01-01

234

Mitotic activity in dorsal epidermis of Rana pipiens.  

NASA Technical Reports Server (NTRS)

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

Garcia-Arce, H.; Mizell, S.

1972-01-01

235

Proteomic analysis of mitotic RNA polymerase II reveals novel interactors and association with proteins dysfunctional in disease.  

PubMed

RNA polymerase II (RNAPII) transcribes protein-coding genes in eukaryotes and interacts with factors involved in chromatin remodeling, transcriptional activation, elongation, and RNA processing. Here, we present the isolation of native RNAPII complexes using mild extraction conditions and immunoaffinity purification. RNAPII complexes were extracted from mitotic cells, where they exist dissociated from chromatin. The proteomic content of native complexes in total and size-fractionated extracts was determined using highly sensitive LC-MS/MS. Protein associations with RNAPII were validated by high-resolution immunolocalization experiments in both mitotic cells and in interphase nuclei. Functional assays of transcriptional activity were performed after siRNA-mediated knockdown. We identify >400 RNAPII associated proteins in mitosis, among these previously uncharacterized proteins for which we show roles in transcriptional elongation. We also identify, as novel functional RNAPII interactors, two proteins involved in human disease, ALMS1 and TFG, emphasizing the importance of gene regulation for normal development and physiology. PMID:22199231

Möller, André; Xie, Sheila Q; Hosp, Fabian; Lang, Benjamin; Phatnani, Hemali P; James, Sonya; Ramirez, Francisco; Collin, Gayle B; Naggert, Jürgen K; Babu, M Madan; Greenleaf, Arno L; Selbach, Matthias; Pombo, Ana

2012-06-01

236

Proteomic Analysis of Mitotic RNA Polymerase II Reveals Novel Interactors and Association With Proteins Dysfunctional in Disease*  

PubMed Central

RNA polymerase II (RNAPII) transcribes protein-coding genes in eukaryotes and interacts with factors involved in chromatin remodeling, transcriptional activation, elongation, and RNA processing. Here, we present the isolation of native RNAPII complexes using mild extraction conditions and immunoaffinity purification. RNAPII complexes were extracted from mitotic cells, where they exist dissociated from chromatin. The proteomic content of native complexes in total and size-fractionated extracts was determined using highly sensitive LC-MS/MS. Protein associations with RNAPII were validated by high-resolution immunolocalization experiments in both mitotic cells and in interphase nuclei. Functional assays of transcriptional activity were performed after siRNA-mediated knockdown. We identify >400 RNAPII associated proteins in mitosis, among these previously uncharacterized proteins for which we show roles in transcriptional elongation. We also identify, as novel functional RNAPII interactors, two proteins involved in human disease, ALMS1 and TFG, emphasizing the importance of gene regulation for normal development and physiology.

Moller, Andre; Xie, Sheila Q.; Hosp, Fabian; Lang, Benjamin; Phatnani, Hemali P.; James, Sonya; Ramirez, Francisco; Collin, Gayle B.; Naggert, Jurgen K.; Babu, M. Madan; Greenleaf, Arno L.; Selbach, Matthias; Pombo, Ana

2012-01-01

237

Nottingham-defined mitotic score: comparison with visual and image cytometric phosphohistone H3 labeling indices and correlation with Oncotype DX recurrence score.  

PubMed

Prognosis of breast cancer patients has been determined traditionally by lymph node status, tumor size, and histologic grade. In recent years the Oncotype DX recurrence score (RS) assay has emerged as an expensive adjunct prognostic tool. Markers of proliferation play a large role in determination of RS, and we have shown previously that immunohistochemical expression of proliferation markers Ki-67 and phosphohistone H3 (PPH3) correlates with RS. Our current goal is comparison of the hematoxylin and eosin (H&E) mitotic score, defined by the Nottingham grading system, with anti-PPH3 mitotic figure labeling assessed by both visual and automated image analysis and correlation of mitotic score results with RS. Estrogen receptor-positive breast carcinomas from 137 patients with Oncotype DX testing were selected. A representative H&E-stained tumor section was evaluated. Mitoses were counted per 10 high-power fields and tumors graded using the Nottingham criteria by 1 pathologist in accordance with College of American Pathologists-recommended mitotic count cutoffs for a field diameter of 0.55 mm. An additional section was immunostained with PPH3 antibody. PPH3 mitotic scores were determined visually and by automated imaging system. Statistical analysis was performed using univariate tests and Spearman coefficient. There was a statistically significant positive correlation among the 3 methods of mitotic score assessment. Specifically, correlation of tumor grades obtained using visual and automated methods of assessment of mitotic activity with PPH3 stain was the strongest and most statistically significant (weighted ? value 0.84, P<0.001; Spearman coefficient 0.89, P<0.001). There was a statistically significant positive correlation between H&E mitosis score and RS (P<0.001, Spearman coefficient 0.30) and between visual PPH3 mitotic score and RS (P<0.001, Spearman coefficient 0.28). In conclusion, mitotic score by any of the 3 methods studied may be useful in assessing tumor grade, proliferation, and prognosis. PMID:22495373

Zbytek, Blazej; Cohen, Cynthia; Wang, Jason; Page, Andrew; Williams, Daron J; Adams, Amy L

2013-01-01

238

The overlooked greatwall: a new perspective on mitotic control.  

PubMed

The role of the dual specificity protein phosphatase, Cdc25, in activating the cyclin-dependent kinase-cyclin B complex (Cdk1-CycB) by overcoming the inhibitory Wee1 kinase is a long-established principle for mitotic entry. Recently, however, evidence has emerged of a regulatory network that facilitates Cdk1-CycB activity by inhibiting the form of protein phosphatase 2A having a B55 regulatory subunit (PP2A-B55). Here, I review the genetic and biochemical evidence for Greatwall kinase and its substrate Endosulphine as the key components of this previously obscure regulatory network. Not only is the inhibition of PP2A-B55 by phospho-endosulphine required to prevent dephosphorylation of Cdk1-CycB substrates until mitotic exit, but it is also required to promote Cdc25 activity and inhibit Wee1 at mitotic entry. I discuss how these alternating states of preferential PP2A-B55 or Cdk1-CycB activity can have an impact upon the regulation of Polo kinase and its ability to bind different partner proteins as mitosis progresses. PMID:22754657

Glover, David M

2012-03-01

239

Staurosporine overrides checkpoints for mitotic onset in BHK cells.  

PubMed

Under normal conditions, mammalian cells will not initiate mitosis in the presence of either unreplicated or damaged DNA. We report here that staurosporine, a tumor promoter and potent protein kinase inhibitor, can uncouple mitosis from the completion of DNA replication and override DNA damage-induced G2 delay. Syrian hamster (BHK) fibroblasts that were arrested in S phase underwent premature mitosis at concentrations as low as 1 ng/ml, with maximum activity seen at 50 ng/ml. Histone H1 kinase activity was increased to approximately one-half the level found in normal mitotic cells. Inhibition of protein synthesis during staurosporine treatment blocked premature mitosis and suppressed the increase in histone H1 kinase activity. In asynchronously growing cells, staurosporine transiently increased the mitotic index and histone H1 kinase activity but did not induce S phase cells to undergo premature mitosis, indicating a requirement for S phase arrest. Staurosporine also bypassed the cell cycle checkpoint that prevents the onset of mitosis in the presence of damaged DNA. The delay in mitotic onset resulting from gamma radiation was reduced when irradiation was followed immediately by exposure to 50 ng/ml of staurosporine. These findings indicate that inhibition of protein phosphorylation by staurosporine can override two important checkpoints for the initiation of mitosis in BHK cells. PMID:1467308

Tam, S W; Schlegel, R

1992-11-01

240

Directional instability of kinetochore motility during chromosome congression and segregation in mitotic newt lung cells: a push-pull mechanism  

Microsoft Academic Search

Most models of mitotic congression and segregation assume that only poleward pulling forces occur at kinetochores. However, there are reports for several different cell types that both mono-oriented and bi-oriented chromosomes oscillate toward and away from the pole throughout mitosis. We used new methods of high resolution video microscopy and computer-assisted tracking techniques to measure the positions over time of

Robert V. Skibbens; Victoria Petrie Skeen; E. D. Salmon

1993-01-01

241

The Spo12 protein of Saccharomyces cerevisiae: a regulator of mitotic exit whose cell cycle-dependent degradation is mediated by the anaphase-promoting complex.  

PubMed Central

The Spo12 protein plays a regulatory role in two of the most fundamental processes of biology, mitosis and meiosis, and yet its biochemical function remains elusive. In this study we concentrate on the genetic and biochemical analysis of its mitotic function. Since high-copy SPO12 is able to suppress a wide variety of mitotic exit mutants, all of which arrest with high Clb-Cdc28 activity, we speculated whether SPO12 is able to facilitate exit from mitosis when overexpressed by antagonizing mitotic kinase activity. We show, however, that Spo12 is not a potent regulator of Clb-Cdc28 activity and can function independently of either the cyclin-dependent kinase inhibitor (CDKi), Sic1, or the anaphase-promoting complex (APC) regulator, Hct1. Spo12 protein level is regulated by the APC and the protein is degraded in G1 by an Hct1-dependent mechanism. We also demonstrate that in addition to localizing to the nucleus Spo12 is a nucleolar protein. We propose a model where overexpression of Spo12 may lead to the delocalization of a small amount of Cdc14 from the nucleolus, resulting in a sufficient lowering of mitotic kinase levels to facilitate mitotic exit. Finally, site-directed mutagenesis of highly conserved residues in the Spo12 protein sequence abolishes both its mitotic suppressor activity as well as its meiotic function. This result is the first indication that Spo12 may carry out the same biochemical function in mitosis as it does in meiosis.

Shah, R; Jensen, S; Frenz, L M; Johnson, A L; Johnston, L H

2001-01-01

242

High resolution CT and histological findings in idiopathic pleuroparenchymal fibroelastosis: Features and differential diagnosis  

PubMed Central

Idiopathic pleuroparenchymal fibroelastosis (IPPFE) is a recently described clinical-pathologic entity characterized by pleural and subpleural parenchymal fibrosis, mainly in the upper lobes. As this disease is extremely rare (only 7 cases have been described in the literature to date) poorly defined cases of IPPFE can go unrecognized. The clinical course of disease is progressive and prognosis is poor, with no therapeutic options other than lung transplantation currently available, yet. The aim of this report is to describe two further cases of this rare disease, reviewing CT, clinical and histological features.

2011-01-01

243

High resolution CT and histological findings in idiopathic pleuroparenchymal fibroelastosis: features and differential diagnosis.  

PubMed

Idiopathic pleuroparenchymal fibroelastosis (IPPFE) is a recently described clinical-pathologic entity characterized by pleural and subpleural parenchymal fibrosis, mainly in the upper lobes. As this disease is extremely rare (only 7 cases have been described in the literature to date) poorly defined cases of IPPFE can go unrecognized.The clinical course of disease is progressive and prognosis is poor, with no therapeutic options other than lung transplantation currently available, yet. The aim of this report is to describe two further cases of this rare disease, reviewing CT, clinical and histological features. PMID:21861891

Piciucchi, Sara; Tomassetti, Sara; Casoni, Gianluca; Sverzellati, Nicola; Carloni, Angelo; Dubini, Alessandra; Gavelli, Giampaolo; Cavazza, Alberto; Chilosi, Marco; Poletti, Venerino

2011-01-01

244

Usual interstitial pneumonia: typical and atypical high-resolution computed tomography features.  

PubMed

The computed tomography appearances of usual interstitial pneumonia (UIP) are usually characteristic, with basal-predominant, peripheral-predominant reticular abnormality and honeycombing. Important complications that may be detected by the radiologist include pulmonary hypertension, lung cancer, and acute exacerbation. As the number of surgical lung biopsies performed for typical UIP declines, histologic findings of UIP are increasingly found in subjects with atypical computed tomographic features. Potential reasons for such discordance may include variability in pathologist interpretation, sampling error on biopsy, biopsy obtained from nonrepresentative site, coexistence of multiple pathologies within the same lung, and familial pulmonary fibrosis. Multidisciplinary diagnosis is critical in resolving these cases. PMID:24480139

Lynch, David A; Huckleberry, Jason M

2014-02-01

245

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

PubMed Central

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 bub2? 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.

2012-01-01

246

TPPII promotes genetic instability by allowing the escape from apoptosis of cells with activated mitotic checkpoints.  

PubMed

Overexpression of TPPII correlates with accelerated growth and the appearance of centrosome and chromosome aberrations, suggesting that the activity of this enzyme may be critical for the induction and/or maintenance of genetic instability in malignant cells. We now find that the length of mitosis and of the entire cell cycle is significantly reduced in TPPII overexpressing HEK293 cells compared to untransfected and control transfected cells. Functional TPPII knockdown by shRNA interference caused a significant slowdown in cell growth and the accumulation of cells that delayed or failed to complete mitosis. TPPII overexpressing cells evade mitotic arrest induced by spindle poisons and display high levels of polyploidy despite the constitutively high expression of major components of the spindle checkpoint. TPPII overexpression correlated with upregulation of IAPs and with resistance to mitochondria dependent apoptosis induced by p53 stabilization. Thus, TPPII appears to promote malignant cell growth by allowing exit from mitosis and the survival of cells with severe mitotic spindle damage. PMID:16762321

Stavropoulou, Vaia; Vasquez, Vanessa; Cereser, Biancastella; Freda, Elio; Masucci, Maria G

2006-07-28

247

Semi-automatic methodologies for landslide features extraction: new opportunities but also challenges from high resolution topography  

NASA Astrophysics Data System (ADS)

In recent years new remotely sensed technologies, such as airborne and terrestrial laser scanner, have improved the detail, and the quality of topographic data with notable advantages over traditional survey techniques (Tarolli et al., 2009). A new generation of high resolution (?3 m) Digital Terrain Models (DTMs) are now available for different areas, and widely used by researchers, offering new opportunities for the scientific community. These data call for the development of the new generation of methodologies for objective extraction of geomorphic features, such as channel heads, channel networks, landslide scars, etc. A high resolution DTM, for example, is able to detect in detail the divergence/convergence areas related to unchannelized/channelized processes respect to a coarse DTM. In last few years different studies used the landform curvature as a useful measure for the interpretation of dominant landform processes (Tarolli and Dalla Fontana, 2009). Curvature has been used to analyze landslide morphology and distribution, and to objectively extract the channel network. In this work, we test the performances of some of these new methodologies for geomorphic features extraction, in order to provide a semi-automatic method to recognize landslide scars in a complex mountainous terrain. The analysis has been carried out using a very high resolution DTM (0.5 m), and different sizes of the moving window for the landform curvature calculation. Statistical dispersion measures (standard deviation, interquartile range, mean and median absolute deviation), and probability plots (quantile-quantile plot) were adopted to objectively define the thresholds of curvature for landslide features extraction. The study was conducted on a study area located in the Eastern Italian Alps, where recent accurate field surveys by DGPS on landslide scars, and a high quality set of airborne laser scanner elevation data are available. The results indicate that curvature maps derived by small moving window sizes are not so representative of local morphology. They do not explore a sufficient range at which landslide features occur. The curvature maps derived by larger moving window sizes overcome this problem, resulting more appropriate for the extraction of surveyed features. The results of our work highlight the capability, but also the challenges of adopted analysis in automated methodologies for geomorphic feature extraction. References Tarolli, P., J R. Arrowsmith, and E. R. Vivoni (2009), Understanding earth surface processes from remotely sensed digital terrain models, Geomorphology, doi:10.1016/j.geomorph.2009.07.005. Tarolli, P., and G. Dalla Fontana (2009), Hillslope-to-valley transition morphology: new opportunities from high resolution DTMs, Geomorphology, doi:10.1016/j.geomorph.2009.02.006.

Tarolli, P.; Sofia, G.; Dalla Fontana, G.

2009-12-01

248

High-resolution spectra of solar magnetic features. II - Magnetic fields of umbral brightenings  

NASA Technical Reports Server (NTRS)

The spectra of Fe I and Fe II Zeeman-sensitive lines enhanced by video processing of CCD images are considered. The magnetic-field variation within umbras is obtained from the nearly complete Zeeman splitting of the Stokes I profile. It is shown that small brightenings within umbrae have magnetic fields nearly equal to or slightly smaller than that of the darker surroundings; these features are also nearly at rest with respect to their surroundings. It is noted that the absence of significant motions in umbral dots implies that radiation transports most of the energy at and immediately below the surface. The small size of the dots implies that, if convective plumes transport energy below the surface of sunspot umbrae, they should have both a lateral extent and a depth of their upper boundary comparable to or smaller than the size of the dot.

Lites, Bruce W.; Bida, Thomas A.; Johannesson, A.; Scharmer, G. B.

1991-01-01

249

High prevalence of infantile encephalitic beriberi with overlapping features of Leigh's disease.  

PubMed

Infantile encephalitic beriberi (IEBB) is a rare form of thiamine deficiency and is poorly described. A proportion of Leigh's disease (LD) patients have similar clinical picture and response to thiamine as beriberi, leading to confusion in diagnosis and management. Data on IEBB and LD is scarce and status of thiamine deficiency in India is controversial. We report several infants with life-threatening respiratory and central nervous system symptoms that overlap between IEBB and LD. Majority had low erythrocyte transketolase levels and responded dramatically to thiamine supplementation suggesting a diagnosis of IEBB. However, presence of characteristic lesions on brain imaging and residual damage in several patients on follow-up does not rule out LD completely. Our study highlights the importance of thiamine deficiency in India, especially in the breast-feds and its overlapping features with LD. Awareness of this common mode of presentation may save patients' lives by early diagnosis and timely thiamine supplementation. PMID:18467350

Rao, S Narasimha; Mani, Shalini; Madap, Karuna; Kumar, M V Kranthi; Singh, Lalji; Chandak, Giriraj Ratan

2008-10-01

250

Brochothrix thermosphacta bacteriophages feature heterogeneous and highly mosaic genomes and utilize unique prophage insertion sites.  

PubMed

Brochothrix belongs to the low-GC branch of Gram-positive bacteria (Firmicutes), closely related to Listeria, Staphylococcus, Clostridium, and Bacillus. Brochothrix thermosphacta is a nonproteolytic food spoilage organism, adapted to growth in vacuum-packaged meats. We report the first genome sequences and characterization of Brochothrix bacteriophages. Phage A9 is a myovirus with an 89-nm capsid diameter and a 171-nm contractile tail; it belongs to the Spounavirinae subfamily and shares significant homologies with Listeria phage A511, Staphylococcus phage Twort, and others. The A9 unit genome is 127 kb long with 11-kb terminal redundancy; it encodes 198 proteins and 6 tRNAs. Phages BL3 and NF5 are temperate siphoviruses with a head diameter of 56 to 59 nm. The BL3 tail is 270 nm long, whereas NF5 features a short tail of only 94 nm. The NF5 genome (36.95 kb) encodes 57 gene products, BL3 (41.52 kb) encodes 65 products, and both are arranged in life cycle-specific modules. Surprisingly, BL3 and NF5 show little relatedness to Listeria phages but rather demonstrate relatedness to lactococcal phages. Peptide mass fingerprinting of viral proteins indicate programmed -1 translational frameshifts in the NF5 capsid and the BL3 major tail protein. Both NF5 and BL3 feature circularly permuted, terminally redundant genomes, packaged by a headful mechanism, and integrases of the serine (BL3) and tyrosine (NF5) types. They utilize unique target sequences not previously described: BL3 inserts into the 3' end of a RNA methyltransferase, whereas NF5 integrates into the 5'-terminal part of a putative histidinol-phosphatase. Interestingly, both genes are reconstituted by phage sequence. PMID:20709901

Kilcher, Samuel; Loessner, Martin J; Klumpp, Jochen

2010-10-01

251

The high frequency and clinical feature of seronegative myasthenia gravis in Southern China.  

PubMed

Anti-acetylcholine receptor antibodies (anti-AChR-Ab) are responsible for the failure of neuromuscular junction in myasthenia gravis (MG). Some anti-AChR-Ab-seronegative MG patients have anti-muscle-specific tyrosine kinase antibodies (anti-MuSk-Ab). Here, the anti-AChR-Ab was tested in 250 MG outpatients from Southern China. While anti-MuSk-Ab was tested in 66 patients who had no anti-AChR-Ab in blood serum, but none of them was positive. The antibodies were measured by a radioimmunoprecipitation assay. The frequency of anti-AChR-Ab was 51.2 %. The percentage of anti-AChR-Ab in ocular type was lower than generalized type (44.9 vs. 66.2 %, P = 0.002). Seronegative MG was characterized by a lower percentage of thymoma than seropositive patients (P = 0.013). It seemed to be less severe in seronegative MG than seropositive MG in these 250 patients. In ocular type, seronegative MG mainly manifesting blepharoptosis but seldom diplopia or eyeball fixation related to ocular movement disability (P = 0.016). While in generalized type, seronegative MG was characterized by a lower percentage of bulbar muscle involvements than seropositive patients (P = 0.005). Logistic regression analysis revealed that bulbar weakness was affected by the existence of anti-AChR antibodies (OR = 3.524, P = 0.015). Besides, seronegative MG tended to be characterized by a lower percentage of neck extensor involvement, but this did not reach significance. The percentage of anti-AChR antibodies was much lower than other countries. Seronegative MG has characteristic clinical features that are different from features of the remaining seropositive MG. This emphasises the predictive value of anti-AChR antibodies analysis in MG patients. PMID:22829131

Feng, Hui-Yu; Wang, Hai-Yan; Liu, Wei-Bin; He, Xue-Tao; Huang, Xin; Luo, Chuan-Ming; Li, Yan

2013-06-01

252

Callous-unemotional features, behavioral inhibition, and parenting: independent predictors of aggression in a high-risk preschool sample  

Microsoft Academic Search

A behaviorally-uninhibited temperament, callous-unemotional (CU) features, and harsh parenting have been associated with specific patterns of aggressive behavior in older children and adolescents. We tested the additive and interactive effects of these factors in predicting different types of aggressive behavior in a high-risk preschool sample. Forty-nine preschoolers and their parents registering for Head Start programs were recruited for participation. Behavioral

Eva R. Kimonis; Paul J. Frick; Neil W. Boris; Anna T. Smyke; Amy H. Cornell; Jamie M. Farrell; Charles H. Zeanah

2006-01-01

253

High-resolution multibeam mapping and submersible surveys of topographic features in the northwestern Gulf of Mexico  

USGS Publications Warehouse

The Flower Garden Banks National Marine Sanctuary (FGBNMS) and the USGS Pacific Seafloor Mapping Project mapped about 2000 km2 of the northwestern Gulf of Mexico continental shelf during June 2002, using a Kongsberg Simrad EM1000 multibeam echosounder. Mapping focused on select topographic highs thave hae been idetnnfied as biological features warranting protection from oil and gas activities by the Minerals Management Service (MMS). The base maps will be used for all future ROV and submersible missions.

Hickerson, E. L.; Schmahl, G. P.; Weaver, D. C.; Gardner, J. V.

2003-01-01

254

Contrasting roles of condensin I and condensin II in mitotic chromosome formation  

PubMed Central

In vertebrates, two condensin complexes exist, condensin I and condensin II, which have differing but unresolved roles in organizing mitotic chromosomes. To dissect accurately the role of each complex in mitosis, we have made and studied the first vertebrate conditional knockouts of the genes encoding condensin I subunit CAP-H and condensin II subunit CAP-D3 in chicken DT40 cells. Live-cell imaging reveals highly distinct segregation defects. CAP-D3 (condensin II) knockout results in masses of chromatin-containing anaphase bridges. CAP-H (condensin I)-knockout anaphases have a more subtle defect, with chromatids showing fine chromatin fibres that are associated with failure of cytokinesis and cell death. Super-resolution microscopy reveals that condensin-I-depleted mitotic chromosomes are wider and shorter, with a diffuse chromosome scaffold, whereas condensin-II-depleted chromosomes retain a more defined scaffold, with chromosomes more stretched and seemingly lacking in axial rigidity. We conclude that condensin II is required primarily to provide rigidity by establishing an initial chromosome axis around which condensin I can arrange loops of chromatin.

Green, Lydia C.; Kalitsis, Paul; Chang, Tsz M.; Cipetic, Miri; Kim, Ji Hun; Marshall, Owen; Turnbull, Lynne; Whitchurch, Cynthia B.; Vagnarelli, Paola; Samejima, Kumiko; Earnshaw, William C.; Choo, K. H. Andy; Hudson, Damien F.

2012-01-01

255

Outcrossing, mitotic recombination, and life-history trade-offs shape genome evolution in Saccharomyces cerevisiae  

PubMed Central

We carried out a population genomic survey of Saccharomyces cerevisiae diploid isolates and find that many budding yeast strains have high levels of genomic heterozygosity, much of which is likely due to outcrossing. We demonstrate that variation in heterozygosity among strains is correlated with a life-history trade-off that involves how readily yeast switch from asexual to sexual reproduction under nutrient stress. This trade-off is reflected in a negative relationship between sporulation efficiency and pseudohyphal development and correlates with variation in the expression of RME1, a transcription factor with pleiotropic effects on meiosis and filamentous growth. Selection for alternate life-history strategies in natural versus human-associated environments likely contributes to differential maintenance of genomic heterozygosity through its effect on the frequency that yeast lineages experience sexual cycles and hence the opportunity for inbreeding. In addition to elevated levels of heterozygosity, many strains exhibit large genomic regions of loss-of-heterozygosity (LOH), suggesting that mitotic recombination has a significant impact on genetic variation in this species. This study provides new insights into the roles that both outcrossing and mitotic recombination play in shaping the genome architecture of Saccharomyces cerevisiae. This study also provides a unique case where stark differences in the genomic distribution of genetic variation among individuals of the same species can be largely explained by a life-history trade-off.

Magwene, Paul M.; Kay?kc?, Omur; Granek, Joshua A.; Reininga, Jennifer M.; Scholl, Zackary; Murray, Debra

2011-01-01

256

TPX2 regulates the localization and activity of Eg5 in the mammalian mitotic spindle  

PubMed Central

Mitotic spindle assembly requires the regulated activity of numerous spindle-associated proteins. In mammalian cells, the Kinesin-5 motor Eg5 interacts with the spindle assembly factor TPX2, but how this interaction contributes to spindle formation and function is not established. Using bacterial artificial chromosome technology, we generated cells expressing TPX2 lacking the Eg5 interaction domain. Spindles in these cells were highly disorganized with multiple spindle poles. The TPX2–Eg5 interaction was required for kinetochore fiber formation and contributed to Eg5 localization to spindle microtubules but not spindle poles. Microinjection of the Eg5-binding domain of TPX2 resulted in spindle elongation, indicating that the interaction of Eg5 with TPX2 reduces motor activity. Consistent with this possibility, we found that TPX2 reduced the velocity of Eg5-dependent microtubule gliding, inhibited microtubule sliding, and resulted in the accumulation of motor on microtubules. These results establish a novel function of TPX2 in regulating the location and activity of the mitotic motor Eg5.

Ma, Nan; Titus, Janel; Gable, Alyssa; Ross, Jennifer L.

2011-01-01

257

Speaker Verification Using Support Vector Machines and High-Level Features  

Microsoft Academic Search

High-level characteristics such as word usage, pronunciation, phonotactics, prosody, etc., have seen a resurgence for automatic speaker recognition over the last several years. With the availability of many conversation sides per speaker in current corpora, high-level systems now have the amount of data needed to sufficiently characterize a speaker. Although a significant amount of work has been done in finding

William M. Campbell; Joseph P. Campbell; Terry P. Gleason; Douglas A. Reynolds; Wade Shen

2007-01-01

258

Risk factors for psychosis in an ultra high-risk group: psychopathology and clinical features  

Microsoft Academic Search

The identification of individuals at high risk of developing a psychotic disorder has long been a goal of clinicians because it is thought that early treatment of this group may prevent onset of the disorder. However, little is known of predictive factors of psychosis, even within a high-risk group. This study followed up 104 young people thought to be at

Alison R Yung; Lisa J Phillips; Hok Pan Yuen; Patrick D McGorry

2004-01-01

259

Mechanisms of Mitotic Cell Death Induced by Chemotherapy Mediated G2 Checkpoint Abrogation  

Microsoft Academic Search

The novel concept of anticancer treatment termed ''G2 checkpoint abrogation'' aims to target p53-deficient tumor cells and is currently explored in clinical trials. The anticancer drug UCN-01 is used to abrogate a DNA damage-induced G2 cell cycle arrest leading to mitotic entry and subsequent cell death, which is poorly defined as ''mitotic cell death'' or ''mitotic catastrophe.'' We show here

Celia Vogel; Christian Hager; Holger Bastians

2007-01-01

260

Mitotic Histone H3 Phosphorylation by Vaccinia-Related Kinase 1 in Mammalian Cells  

Microsoft Academic Search

Mitotic chromatin condensation is essential for cell division in eukaryotes. Posttranslational modification of the N-terminal tail of histone proteins, particularly by phosphorylation by mitotic histone kinases, may facilitate this process. In mammals, aurora B is believed to be the mitotic histone H3 Ser10 kinase; however, it is not sufficient to phosphorylate H3 Ser10 with aurora B alone. We show that

Tae-Hong Kang; Do-Young Park; Yoon Ha Choi; Kyung-Jin Kim; Ho Sup Yoon; Kyong-Tai Kim

2007-01-01

261

Features of the structure and properties of high-speed steels after laser treatment  

Microsoft Academic Search

1.Depending upon the nature of the processes occurring in high-speed steels in laser treatment, their hardness may be higher or lower than the hardness obtained both directly after through hardening and after the standard heat treatment (harden and triple temper at 560°C).2.In the zone formed as the result of rapid laser tempering the hardness of the high-speed steels decreases from

V. S. D'yachenko

1985-01-01

262

MOVING MAGNETIC FEATURES AROUND AR 10930 FROM HIGH-RESOLUTION DATA OBSERVED BY HINODE/SOT  

SciTech Connect

We investigate the origin, configuration, and evolution of moving magnetic features (MMFs) in the moat and penumbra regions of NOAA AR 10930 using Hinode/SOT filtergrams and magnetograms. We differentiate MMFs into four types in terms of the location of first appearance and the source of initial flux. The main results are summed up as follows: (1) 50% of the MMFs are produced from or within the penumbra, while 50% are produced within the moat. The MMFs formed in the penumbra normally move outward along radial directions. The MMFs formed in the moat have more dispersed directions of motion. The average speed of most MMFs decreases radially. (2) About 63% of moat fluxes are input by flux emergences. Newly emerged MMFs are normally smaller in size. In their rise phase, they gain flux by adding newly emerging flux or merging other elements, and in the decline phase they lose flux by flux cancellation or fragmentation. The MMFs that are fragments separated from penumbra or other magnetic elements usually have larger flux and longer lifetime. They start their decay process once they are formed. Frequent merging and flux cancellation between MMFs are the dominant factors in MMFs' evolution. (3) Cancellations between opposite-polarity magnetic elements are responsible for most of the low chromospheric bright points. Bipole emergence and MMFs' severance from the penumbra also produce bright points. Elongated or horn-shaped micro-filaments may appear during the separation or cancellation process between magnetic elements.

Li Xiaobo; Zhang Hongqi, E-mail: xiaobo_li_naoc@yahoo.com [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

2013-07-01

263

Deciphering global signal features of high-throughput array data from cancers.  

PubMed

Normalization of array data relies on the assumption that most genes are not altered, which means that the signals for different samples should be scaled to have similar median or average values. However, accumulating evidence suggests that gene expression could be widely up-regulated in cancers. Our previous results and subsequent findings have shown that violation of the assumption led to erroneous interpretation of microarray data. To decipher the global signal features of microarray data from cancer samples, we empirically evaluated a large collection of gene and miRNA expression profiles and copy-number variation arrays. Our results showed that, at the transcriptomic level, genes and miRNAs are widely over-expressed in a large proportion of cancers. In contrast, at the genomic level, global raw signal intensities for methylation and copy number variation show negligible differences between cancer and normal samples. These results force us to re-evaluate the proper use of normalization procedures under different experimental conditions and for different array platforms. PMID:24695970

Wu, Deng; Kang, Juanjuan; Huang, Yan; Li, Xiang; Wang, Xiansong; Huang, Dan; Wang, Yuting; Li, Bin; Hao, Dapeng; Gu, Qi; Tang, Nelson; Li, Kongning; Guo, Zheng; Li, Xia; Xu, Jianzhen; Wang, Dong

2014-06-01

264

Sequence composition similarities with the 7SL RNA are highly predictive of functional genomic features  

PubMed Central

Transposable elements derived from the 7SL RNA gene, such as Alu elements in primates, have had remarkable success in several mammalian lineages. The results presented here show a broad spectrum of functions for genomic segments that display sequence composition similarities with the 7SL RNA gene. Using thoroughly documented loci, we report that DNaseI-hypersensitive sites can be singled out in large genomic sequences by an assessment of sequence composition similarities with the 7SL RNA gene. We apply a root word frequency approach to illustrate a distinctive relationship between the sequence of the 7SL RNA gene and several classes of functional genomic features that are not presumed to be of transposable origin. Transposable elements that show noticeable similarities with the 7SL sequence include Alu sequences, as expected, but also long terminal repeats and the 5?-untranslated regions of long interspersed repetitive elements. In sequences masked for repeated elements, we find, when using the 7SL RNA gene as query sequence, distinctive similarities with promoters, exons and distal gene regulatory regions. The latter being the most notoriously difficult to detect, this approach may be useful for finding genomic segments that have regulatory functions and that may have escaped detection by existing methods.

Paquet, Yanick; Anderson, Alan

2010-01-01

265

Immersion scatterometry for improved feature resolution and high speed acquisition of resist profiles  

NASA Astrophysics Data System (ADS)

Specular-mode spectroscopic scatterometry is currently being used as an in-line metrology tool for wafer-to-wafer process monitoring and control in lithography and etch processes. Experimental real-time, in situ demonstrations of critical dimension monitoring and control have been made for reactive ion etching. There have been no similar demonstrations of real-time control in the critical step of resist development. In this paper, we will show the results of a simulation study on the use of scatterometry in an immersion mode both to improve resolution and to act as a real-time monitor for photoresist topography evolution during development. We have performed realistic simulations of the experimental performance by using Prolith to generate developing resist profiles vs. time and a rigorous couple wave algorithm (RCWA) simulator (modified to include the immersion ambient) to generate simulated scatterometry data. We have examined several modes of operation of the proposed measurement including specular and 1st order scattered modes using spectroscopic ellipsometry and reflectometry. For our simulations, we have used pure water to approximate the developer refractive index. We have created realistic simulation data by adding appropriate amounts of random noise to perfect simulations, and then used regression analysis to extract profiles from these data. Water immersion increases feature shape resolution for small period gratings by increasing the scattering into real diffracted modes.

Terry, Fred L., Jr.; Bendik, Joseph J.

2005-05-01

266

A Selective Overview of Variable Selection in High Dimensional Feature Space  

PubMed Central

High dimensional statistical problems arise from diverse fields of scientific research and technological development. Variable selection plays a pivotal role in contemporary statistical learning and scientific discoveries. The traditional idea of best subset selection methods, which can be regarded as a specific form of penalized likelihood, is computationally too expensive for many modern statistical applications. Other forms of penalized likelihood methods have been successfully developed over the last decade to cope with high dimensionality. They have been widely applied for simultaneously selecting important variables and estimating their effects in high dimensional statistical inference. In this article, we present a brief account of the recent developments of theory, methods, and implementations for high dimensional variable selection. What limits of the dimensionality such methods can handle, what the role of penalty functions is, and what the statistical properties are rapidly drive the advances of the field. The properties of non-concave penalized likelihood and its roles in high dimensional statistical modeling are emphasized. We also review some recent advances in ultra-high dimensional variable selection, with emphasis on independence screening and two-scale methods.

Fan, Jianqing

2010-01-01

267

Deltex-1 Activates Mitotic Signaling and Proliferation and Increases the Clonogenic and Invasive Potential of U373 and LN18 Glioblastoma Cells and Correlates with Patient Survival  

PubMed Central

Glioblastoma (GBM) is a highly malignant primary tumor of the central nervous system originating in glial cells. GBM results in more years of life lost than any other cancer type. Low levels of Notch receptor expression correlates with prolonged survival in various high grade gliomas independent of other markers. Different downstream pathways of Notch receptors have been identified. We tested if the Notch/Deltex pathway, which is distinct from the canonical, CSL-mediated pathway, has a role in GBM. We show that the alternative or non-canonical Notch pathway functioning through Deltex1 (DTX1) mediates key features of glioblastoma cell aggressiveness. For example, DTX1 activates the RTK/PI3K/PKB and the MAPK/ERK mitotic pathways and induces anti-apoptotic Mcl-1. The clonogenic and growth potential of established glioma cells correlated with DTX1 levels. Microarray gene expression analysis further identified a DTX1-specific, MAML1-independent transcriptional program - including microRNA-21- which is functionally linked to the changes in tumor cell aggressiveness. Over-expression of DTX1 increased cell migration and invasion correlating to ERK activation, miR-21 levels and endogenous Notch levels. In contrast to high and intermediate expressors, patients with low DTX1 levels have a more favorable prognosis. The alternative Notch pathway via DTX1 appears to be an oncogenic factor in glioblastoma and these findings offer new potential therapeutic targets.

Huber, Roland M.; Rajski, Michal; Sivasankaran, Balasubramanian; Moncayo, Gerald; Hemmings, Brian A.; Merlo, Adrian

2013-01-01

268

Deltex-1 activates mitotic signaling and proliferation and increases the clonogenic and invasive potential of U373 and LN18 glioblastoma cells and correlates with patient survival.  

PubMed

Glioblastoma (GBM) is a highly malignant primary tumor of the central nervous system originating in glial cells. GBM results in more years of life lost than any other cancer type. Low levels of Notch receptor expression correlates with prolonged survival in various high grade gliomas independent of other markers. Different downstream pathways of Notch receptors have been identified. We tested if the Notch/Deltex pathway, which is distinct from the canonical, CSL-mediated pathway, has a role in GBM. We show that the alternative or non-canonical Notch pathway functioning through Deltex1 (DTX1) mediates key features of glioblastoma cell aggressiveness. For example, DTX1 activates the RTK/PI3K/PKB and the MAPK/ERK mitotic pathways and induces anti-apoptotic Mcl-1. The clonogenic and growth potential of established glioma cells correlated with DTX1 levels. Microarray gene expression analysis further identified a DTX1-specific, MAML1-independent transcriptional program - including microRNA-21- which is functionally linked to the changes in tumor cell aggressiveness. Over-expression of DTX1 increased cell migration and invasion correlating to ERK activation, miR-21 levels and endogenous Notch levels. In contrast to high and intermediate expressors, patients with low DTX1 levels have a more favorable prognosis. The alternative Notch pathway via DTX1 appears to be an oncogenic factor in glioblastoma and these findings offer new potential therapeutic targets. PMID:23451269

Huber, Roland M; Rajski, Michal; Sivasankaran, Balasubramanian; Moncayo, Gerald; Hemmings, Brian A; Merlo, Adrian

2013-01-01

269

Working hard for recovery: mitotic kinases in the DNA damage checkpoint  

PubMed Central

Cell division in mitosis is tightly regulated via a group of protein kinases. Activation of these mitotic kinases is inhibited by the DNA damage checkpoint that arrests the cell cycle in interphase and prevents mitotic entry. Interestingly, it has been shown that the DNA damage checkpoint is feedback regulated by several mitotic kinases. These kinases are reactivated from checkpoint arrest to deactivate the checkpoint and restart cell cycle progression, thereby allowing the cell to recover from the DNA damage checkpoint. The emerging role of mitotic kinases in the DNA damage pathway provides important insights into cancer progression and treatment.

2013-01-01

270

Large Erosional Features on the Cascadia Accretionary Wedge Imaged with New High-Resolution Multibeam Bathymetry and Seismic Datasets  

NASA Astrophysics Data System (ADS)

Utilizing new high resolution multibeam bathymetric data along with chirp sub-bottom and multichannel seismic reflection (MCS) data, we identified remarkable erosional features on the toe of the Cascadia accretionary wedge near Willapa Canyon, offshore Washington, USA. Bathymetric data was compiled from the Cascadia Open-Access Seismic Transects (COAST) cruise and from the site survey cruise for the Cascadia Initiative. These features loosely resemble slope failures of the frontal thrust, but can be distinguished from such failures by several key features: They incise the crest of the frontal thrust and encompass the landward limb; They have floors below the level of the abyssal plain, similar to plunge pool morphology; They show no evidence of landslide blocks at the base of the slope indicative of block sliding. The features where likely formed during the latest Pleistocene based on post event deposition, cross-cutting relationships with Juan de Fuca Channel and the Willapa Channel levees and wave field, and post event slip on the frontal thrust of the Cascadia accretionary prism. The Holocene levees of both Willapa Channel and Juan de Fuca Channel overlap these older features, and clearly place an upper bound on the age of the erosional features in the latest Pleistocene. A lower bound is estimated from a sub-bottom profile that images ~30 meters of post scour sediment fill. Using existing literature of Holocene and Pleistocene sedimentation rates we estimate a lower age bound between ~23,000 - 56,000 y.b.p. We also map a fault scarp within the erosional feature, with ~60 m of vertical offset. Using multi-channel seismic reflection profiles from the COAST cruise we interpret this scarp as the surface expression of the landward vergent frontal thrust fault. The apparent short duration of the erosional event along the seaward margin of the accretionary wedge, coupled with the presence of the fresh fault scarp within the erosion zone, are indicative of a dormant feature with significant time required to develop the scarp after cessation of the causative process. Based on morphology, dissimilarity with other submarine features, and available age constraints, we infer that these features were most likely formed during the glacial lake outpouring in the Pacific Northwest known as the Missoula floods which occurred 13,000-19,500 y.b.p. The features themselves bear a strong resemblance to 'coulees' formed during the same glacial events onshore, and the outpourings through Willapa Channel are consistent with previous inferences of the deposition of Missoula Flood deposits in Escanaba Trough. If this timing is correct, the slip rate along the Cascadia frontal thrust can be estimated using fault geometry and scarp height as 2.8 - 4.1 mm/yr.

Beeson, J. W.; Goldfinger, C.

2013-12-01

271

MYC High Level Gene Amplification Is a Distinctive Feature of Angiosarcomas after Irradiation or Chronic Lymphedema  

PubMed Central

Angiosarcomas (AS) are rare vascular malignancies that arise either de novo as primary tumors or secondary to irradiation or chronic lymphedema. The cytogenetics of angiosarcomas are poorly characterized. We applied array-comparative genomic hybridization as a screening method to identify recurrent alterations in 22 cases. Recurrent genetic alterations were identified only in secondary but not in primary AS. The most frequent recurrent alterations were high level amplifications on chromosome 8q24.21 (50%), followed by 10p12.33 (33%) and 5q35.3 (11%). Fluorescence in situ hybridization analysis in 28 primary and 33 secondary angiosarcomas (31 tumors secondary to irradiation, 2 tumors secondary to chronic lymphedema) confirmed high level amplification of MYC on chromosome 8q24.21 as a recurrent genetic alteration found exclusively in 55% of AS secondary to irradiation or chronic lymphedema, but not in primary AS. Amplification of MYC did not predispose to high grade morphology or increased cell turnover. In conclusion, despite their identical morphology, secondary AS are genetically different from primary AS and are characterized by a high frequency of high level amplifications of MYC. This finding may have implications both for the diagnosis and treatment of these tumors.

Manner, Johanna; Radlwimmer, Bernhard; Hohenberger, Peter; Mossinger, Katharina; Kuffer, Stefan; Sauer, Christian; Belharazem, Djeda; Zettl, Andreas; Coindre, Jean-Michel; Hallermann, Christian; Hartmann, Jorg Thomas; Katenkamp, Detlef; Katenkamp, Kathrin; Schoffski, Patrick; Sciot, Raf; Wozniak, Agnieszka; Lichter, Peter; Marx, Alexander; Strobel, Philipp

2010-01-01

272

Mitochondrial genome regulates mitotic fidelity by maintaining centrosomal homeostasis.  

PubMed

Centrosomes direct spindle morphogenesis to assemble a bipolar mitotic apparatus to enable error-free chromosome segregation and preclude chromosomal instability (CIN). Amplified centrosomes, a hallmark of cancer cells, set the stage for CIN, which underlies malignant transformation and evolution of aggressive phenotypes. Several studies report CIN and a tumorigenic and/or aggressive transformation in mitochondrial DNA (mtDNA)-depleted cells. Although several nuclear-encoded proteins are implicated in centrosome duplication and spindle organization, the involvement of mtDNA encoded proteins in centrosome amplification (CA) remains elusive. Here we show that disruption of mitochondrial function by depletion of mtDNA induces robust CA and mitotic aberrations in osteosarcoma cells. We found that overexpression of Aurora A, Polo-like kinase 4 (PLK4), and Cyclin E was associated with emergence of amplified centrosomes. Supernumerary centrosomes in rho0 (mtDNA-depleted) cells resulted in multipolar mitoses bearing "real" centrosomes with paired centrioles at the multiple poles. This abnormal phenotype was recapitulated by inhibition of respiratory complex I in parental cells, suggesting a role for electron transport chain (ETC) in maintaining numeral centrosomal homeostasis. Furthermore, rho0 cells displayed a decreased proliferative capacity owing to a G 2/M arrest. Downregulation of nuclear-encoded p53 in rho0 cells underscores the importance of mitochondrial and nuclear genome crosstalk and may perhaps underlie the observed mitotic aberrations. By contrast, repletion of wild-type mtDNA in rho0 cells (cybrid) demonstrated a much lesser extent of CA and spindle multipolarity, suggesting partial restoration of centrosomal homeostasis. Our study provides compelling evidence to implicate the role of mitochondria in regulation of centrosome duplication, spindle architecture, and spindle pole integrity. PMID:24799670

Donthamsetty, Shashikiran; Brahmbhatt, Meera; Pannu, Vaishali; Rida, Padmashree Cg; Ramarathinam, Sujatha; Ogden, Angela; Cheng, Alice; Singh, Keshav K; Aneja, Ritu

2014-07-01

273

Stimulated Raman scattering as an explanation for the extreme high-velocity features of water maser emission  

NASA Astrophysics Data System (ADS)

Extreme high-velocity features in the water maser spectra with velocity shifts of about +/- 900 km/s have recently been detected in the extragalactic water maser source, NGC 4258. We explain these extreme high-velocity features of water masers by stimulated Raman scattering in the plasma of the electron density of about 106-107/cu cm. For the Raman masers to occur, the brightness temperature of the original masers must be greater than about 1016-1019 K (depending on the maser beam solid angles, etc.), and the amplification path length of the maser must be about 3 x 1014 cm. We show that the frequency-downshifted (Stokes) photons are produced by the backward scattering and that upshifted (anti-Stokes) photons are created by interacting intersecting masers in the plasma. The intensity of the upshifted component is slightly lower than the intensity of the downshifted component. Time variations of upshifted and downshifted features must be independent. A crucial test for the Raman maser model is proposed.

Deguchi, Shuji

1994-01-01

274

High-Definition Optical Coherence Tomography Features of Primary Vitreoretinal Lymphoma  

PubMed Central

Primary vitreoretinal lymphoma is a high-grade in-traocular malignancy that presents as a vitritis with creamy subretinal lesions. In cases where the vitritis is dense, the characteristic subretinal lesions can be dif-ficult to see on clinical examination. Novel high-definition imaging techniques that allow for deeper penetration through opaque media could have diagnostic utility in such cases. The authors present a case of a patient who presented with a dense vitritis that precluded visualization of fundus details. Spectral-domain optical coherence tomography using high-definition raster imaging demonstrated subretinal deposits along with outer retinal atrophy. These findings were suggestive of primary vitreoretinal lymphoma and prompted diagnostic vitrectomy. Pathological examination of the vitreous specimen confirmed the diagnosis of primary vitreoretinal lymphoma.

Forooghian, Farzin; Merkur, Andrew B.; White, Valerie A.; Shen, Defen; Chan, Chi-Chao

2012-01-01

275

DNAshape: a method for the high-throughput prediction of DNA structural features on a genomic scale.  

PubMed

We present a method and web server for predicting DNA structural features in a high-throughput (HT) manner for massive sequence data. This approach provides the framework for the integration of DNA sequence and shape analyses in genome-wide studies. The HT methodology uses a sliding-window approach to mine DNA structural information obtained from Monte Carlo simulations. It requires only nucleotide sequence as input and instantly predicts multiple structural features of DNA (minor groove width, roll, propeller twist and helix twist). The results of rigorous validations of the HT predictions based on DNA structures solved by X-ray crystallography and NMR spectroscopy, hydroxyl radical cleavage data, statistical analysis and cross-validation, and molecular dynamics simulations provide strong confidence in this approach. The DNAshape web server is freely available at http://rohslab.cmb.usc.edu/DNAshape/. PMID:23703209

Zhou, Tianyin; Yang, Lin; Lu, Yan; Dror, Iris; Dantas Machado, Ana Carolina; Ghane, Tahereh; Di Felice, Rosa; Rohs, Remo

2013-07-01

276

Precise ego-localization in urban areas using Laserscanner and high accuracy feature maps  

Microsoft Academic Search

Robust ego-localization is an essential technology for future intelligent vehicles and cooperative applications. In this paper a new localization algorithm based on IBEO AS Laserscanners and high accuracy digital maps is proposed. Algorithms to create accurate grid maps with Laserscanners and the extraction of static objects used as landmarks for ego-localization is introduced. The key problem in landmark navigation in

Thorsten Weiss; Nico Kaempchen; K. Dietmayer

2005-01-01

277

Dosimetric features and kinetic analysis of thermoluminescence from ultra-high molecular weight polyethylene  

Microsoft Academic Search

Thermoluminescence (TL) from beta irradiated ultra-high molecular weight polyethylene has been studied for measurements between 30 and 200 °C. An aliquot studied in this work produced TL glow curves consisting of two peaks, the main peak at 88 °C and a weaker intensity peak at 148 °C for heating at 1 °C s?1 following an excitation dose of 215 Gy.

M L Chithambo

2012-01-01

278

Mapping electrodynamic features of the high-latitude ionosphere from localized observations - Technique  

Microsoft Academic Search

This paper describes a novel procedure for mapping high-latitude electric fields and currents and their associated magnetic variations, using sets of localized observational data derived from different types of measurements. The technique provides a formalism for incorporating simultaneously such different classes of data as electric fields from radars and satellites, electric currents from radars, and magnetic perturbations at the ground

A. D. Richmond; Y. Kamide

1988-01-01

279

Intermittency feature of shear stress fluctuation in high-Reynolds-number turbulence  

Microsoft Academic Search

Instantaneous shear stress fluctuations are considered for high-Reynolds-number (up to Rlambda~104) turbulent flow field using the concept of maximum norm. The maximum norm is defined as the largest change within a box of a given size. We have applied this technique to a variety of flow fields and a wide range of Reynolds numbers. Results indicated that the maximum norm

Yoshiyuki Tsuji; Brindesh Dhruva

1999-01-01

280

Domain-Specific Feature Modeling for High Integrity Vehicle Control System Functional Design  

Microsoft Academic Search

Vehicle control system development is a complex process, involving multiple stages and multiple groups in different disciplines. Constructing a high-integrity configuration for a product with a large number of control functions is very challenging in current practice because of lacking effective modeling methods to capture and maintain the individually-developed functions and their relations in the configurations for a large variety

Shige Wang

2010-01-01

281

Mapping electrodynamic features of the high-latitude ionosphere from localized observations - Technique  

NASA Technical Reports Server (NTRS)

This paper describes a novel procedure for mapping high-latitude electric fields and currents and their associated magnetic variations, using sets of localized observational data derived from different types of measurements. The technique provides a formalism for incorporating simultaneously such different classes of data as electric fields from radars and satellites, electric currents from radars, and magnetic perturbations at the ground and at satellite heights; the technique also uses available statistical information on the averages and variances of electrodynamic fields. The technique provides a more rigorous way of quantitatively estimating high-latitude electric field and current patterns than other methods and has a capability to quantify the errors in the mapped fields, based on the distribution of available data, their errors, and the statistical variances of the fields. The technique is illustrated by an application to a substorm which was analyzed by Kamide et al. (1982) by an earlier technique.

Richmond, A. D.; Kamide, Y.

1988-01-01

282

Study of High/Low Amplitude Wave Trains in CR Intensity and Associated Solar Features  

NASA Astrophysics Data System (ADS)

Cosmic Ray intensity data for a period of over a decade (i.e., 1989-1990) from various neutron-monitoring stations; situated at different latitudes, have been investigated for the high/low amplitude anisotropic wave train events (HAE/LAE). It has been found that the diurnal phase of cosmic ray anisotropy appears to be indep endent of amplitude, as no synchronization in variations is seen between them for ma jority of the HAE/LAE cases. However, the phase of the semi-diurnal anisotropy for HAE has been found to shift towards later hours for all the events. The geomagnetic activity index Ap has been observed to remain low during the period of each HAE/LAE. The possible phenomenon to cause such high/low amplitude anisotropic wave trains has been proposed to appear on the back of the visible side of the Sun.

Dubey, S. K.; Kumar, Santosh; Kathal, B.K.; Richharia, M.K.

2003-07-01

283

High Performance Transistors Featured in an Aggressively Scaled 45nm Bulk CMOS Technology  

Microsoft Academic Search

An aggressively scaled high performance 45 nm bulk CMOS technology targeting graphic, gaming, wireless and digital home applications is presented. Through innovative utilization and integration of advanced stressors, thermal processes and other technology elements, at aggressively scaled 45 nm design ground rules, core NFET and PFET realized world leading drive currents of 1150 and 785 uA\\/um at 100 nA\\/um off

Z. Luo; N. Rovedo; S. Ong; B. Phoong; M. Eller; H. Utomo; C. Ryou; H. Wang; R. Stierstorfer; L. Clevenger; S. Kim; J. Toomey; D. Sciacca; J. Li; W. Wille; L. Zhao; L. Teo; T. Dyer; S. Fang; J. Yan; O. Kwon; J. Holt; J. Han; V. Chan; T. K. J. Yuan; H. Lee; S. Lee; A. Vayshenker; Z. Yang; C. Tian; H. Ng; H. Shang; M. Hierlemann; J. Ku; J. Sudijono; M. Ieong

2007-01-01

284

Features of brittle damages and hydrogen impregnation of high-pressure boiler tube metal  

Microsoft Academic Search

A significant number of failures encountered in high-pressure steam boilers of thermal electric power stations are caused by damage of the tubes of the steam superheaters, which are made of 20, 12Kh1MF, 12Kh2MFSR and 12Kh18N10T steels. A statistical analysis made by the authors determined that a large number of the failures result from the action of hydrogen on the tubes.

A. B. Vainman; O. D. Smiyan; So I. Girnyi; N. P. Kostyuchenko; A. V. Vasilik; R. K. Melekhov

1988-01-01

285

Extraction of Features from High-resolution 3D LiDaR Point-cloud Data  

NASA Astrophysics Data System (ADS)

Airborne and tripod-based LiDaR scans are capable of producing new insight into geologic features by providing high-quality 3D measurements of the landscape. High-resolution LiDaR is a promising method for studying slip on faults, erosion, and other landscape-altering processes. LiDaR scans can produce up to several billion individual point returns associated with the reflection of a laser from natural and engineered surfaces; these point clouds are typically used to derive a high-resolution digital elevation model (DEM). Currently, there exist only few methods that can support the analysis of the data at full resolution and in the natural 3D perspective in which it was collected by working directly with the points. We are developing new algorithms for extracting features from LiDaR scans, and present method for determining the local curvature of a LiDaR data set, working directly with the individual point returns of a scan. Computing the curvature enables us to rapidly and automatically identify key features such as ridge-lines, stream beds, and edges of terraces. We fit polynomial surface patches via a moving least squares (MLS) approach to local point neighborhoods, determining curvature values for each point. The size of the local point neighborhood is defined by a user. Since both terrestrial and airborne LiDaR scans suffer from high noise, we apply additional pre- and post-processing smoothing steps to eliminate unwanted features. LiDaR data also captures objects like buildings and trees complicating greatly the task of extracting reliable curvature values. Hence, we use a stochastic approach to determine whether a point can be reliably used to estimate curvature or not. Additionally, we have developed a graph-based approach to establish connectivities among points that correspond to regions of high curvature. The result is an explicit description of ridge-lines, for example. We have applied our method to the raw point cloud data collected as part of the GeoEarthScope B-4 project on a section of the San Andreas Fault (Segment SA09). This section provides an excellent test site for our method as it exposes the fault clearly, contains few extraneous structures, and exhibits multiple dry stream-beds that have been off-set by motion on the fault.

Keller, P.; Kreylos, O.; Hamann, B.; Kellogg, L. H.; Cowgill, E. S.; Yikilmaz, M. B.; Hering-Bertram, M.; Hagen, H.

2008-12-01

286

Fusion of symbolic and feature information for high-level object recognition  

NASA Astrophysics Data System (ADS)

In this paper, we present an algorithm which uses symbolic as well as physical labels on the edges and surfaces to constrain the scene-model matching process. Symbolic labels are used to distinguish between curved and planar objects, occluding edges, background surface, etc. These are used along with physical labels such as distances and angles to prune the matching graph. This paper describes a real time object recognition environment that integrates the pruning method described above with low level image processing and high level object recognition algorithms. Results are reported for synthetic and real range images. Our results show that inclusion of symbolic labels improves the accuracy and efficiency of matching.

Shrikhande, Neelima; Getzinger, Jim

1993-04-01

287

Very compact, high-stability electrostatic actuator featuring contact-free self-limiting displacement  

DOEpatents

A compact electrostatic actuator is disclosed for microelectromechanical (MEM) applications. The actuator utilizes stationary and moveable electrodes, with the stationary electrodes being formed on a substrate and the moveable electrodes being supported above the substrate on a frame. The frame provides a rigid structure which allows the electrostatic actuator to be operated at high voltages (up to 190 Volts) to provide a relatively large actuation force compared to conventional electrostatic comb actuators which are much larger in size. For operation at its maximum displacement, the electrostatic actuator is relatively insensitive to the exact value of the applied voltage and provides a self-limiting displacement.

Rodgers, M. Steven (Albuquerque, NM); Miller, Samuel L. (Albuquerque, NM)

2003-01-01

288

The Features of Carbon Nanotubes Grown in High Isostatic Pressure Apparatus from the Nanodiamond Powder  

NASA Astrophysics Data System (ADS)

Multiwalled carbon nanotubes were synthesized in high isostatic pressure (HIP) apparatus in nitrogen at 1650 °C and 2 MPa. The synthesis was performed with nanodiamonds as a precursor of carbon and with ferrocene as a catalyst. Transmission electron microscopy studies demonstrate that the product of the synthesis contains carbon nanotubes filled with iron-based nanoparticles. It was established that in the most of the cases these nanoparticles represent themselves iron carbide Fe3C (cementite). Several times we observed pure iron (?- and ?-Fe) inside the nanotubes. The orientation of the iron and iron carbide particles with respect to the nanotubes axes was investigated.

Buranova, Yu. S.; Kulnitskiy, B. A.; Perezhogin, I. A.; Bagramov, R. H.; Dubitsky, G. A.; Blank, V. D.

2013-05-01

289

NuMA is required for the organization of microtubules into aster-like mitotic arrays  

PubMed Central

NuMA (Nuclear protein that associates with the Mitotic Apparatus) is a 235-kD intranuclear protein that accumulates at the pericentrosomal region of the mitotic spindle in vertebrate cells. To determine if NuMA plays an active role in organizing the microtubules at the polar region of the mitotic spindle, we have developed a cell free system for the assembly of mitotic asters derived from synchronized cultured cells. Mitotic asters assembled in this extract are composed of microtubules arranged in a radial array that contain NuMA concentrated at the central core. The organization of microtubules into asters in this cell free system is dependent on NuMA because immunodepletion of NuMA from the extract results in randomly dispersed microtubules instead of organized mitotic asters, and addition of the purified recombinant NuMA protein to the NuMA-depleted extract fully reconstitutes the organization of the microtubules into mitotic asters. Furthermore, we show that NuMA is phosphorylated upon mitotic aster assembly and that NuMA is only required in the late stages of aster assembly in this cell free system consistent with the temporal accumulation of NuMA at the polar ends of the mitotic spindle in vivo. These results, in combination with the phenotype observed in vivo after the prevention of NuMA from targeting onto the mitotic spindle by antibody microinjection, suggest that NuMA plays a functional role in the organization of the microtubules of the mitotic spindle.

1995-01-01

290

The essential mitotic peptidyl-prolyl isomerase Pin1 binds and regulates mitosis-specific phosphoproteins  

PubMed Central

Phosphorylation of mitotic proteins on the Ser/Thr-Pro motifs has been shown to play an important role in regulating mitotic progression. Pin1 is a novel essential peptidyl–prolyl isomerase (PPIase) that inhibits entry into mitosis and is also required for proper progression through mitosis, but its substrate(s) and function(s) remain to be determined. Here we report that in both human cells and Xenopus extracts, Pin1 interacts directly with a subset of mitotic phosphoproteins on phosphorylated Ser/Thr-Pro motifs in a phosphorylation-dependent and mitosis-specific manner. Many of these Pin1-binding proteins are also recognized by the monoclonal antibody MPM-2, and they include the important mitotic regulators Cdc25, Myt1, Wee1, Plk1, and Cdc27. The importance of this Pin1 interaction was tested by constructing two Pin1 active site point mutants that fail to bind a phosphorylated Ser/Thr-Pro motif in mitotic phosphoproteins. Wild-type, but not mutant, Pin1 inhibits both mitotic division in Xenopus embryos and entry into mitosis in Xenopus extracts. We have examined the interaction between Pin1 and Cdc25 in detail. Pin1 not only binds the mitotic form of Cdc25 on the phosphorylation sites important for its activity in vitro and in vivo, but it also inhibits its activity, offering one explanation for the ability of Pin1 to inhibit mitotic entry. In a separate paper, we have shown that Pin1 is a phosphorylation-dependent PPIase that can recognize specifically the phosphorylated Ser/Thr-Pro bonds present in mitotic phosphoproteins. Thus, Pin1 likely acts as a general regulator of mitotic proteins that have been phosphorylated by Cdc2 and other mitotic kinases.

Shen, Minhui; Stukenberg, P. Todd; Kirschner, Marc W.; Lu, Kun Ping

1998-01-01

291

Collecting Inexpensive High Resolution Aerial and Stereo Images of Small- to Mid-Scale Geomorphic and Tectonic Features  

NASA Astrophysics Data System (ADS)

Methods for collecting accurate, mm- to cm-scale stereoscopic aerial imagery of both small- and mid-scale geomorphic features are developed for a one-time cost of under $1500. High resolution aerial images are valuable for documenting and analyzing small- to mid-scale geomorphic and tectonic features. However, collecting images of mid-scale features such as landslides, rock glaciers, fault scarps, and cinder cones is expensive and makes studies that rely on high resolution repeat imagery prohibitive for undergraduate geology departments with limited budgets. In addition to cost, collecting images of smaller scale geomorphic features such as gravel bars is often impeded by overhanging vegetation or other features in the immediate environment that make impractical the collection of aerial images using standard airborne techniques. The methods provide high resolution stereo photos suitable for image processing and stereographic analysis; the images are potentially suitable for change analyses, velocity tracking, and construction of lidar-resolution digital elevation models. We developed two techniques. The technique suitable for small-scale features (such as gravel bars) utilizes two Nikon D3000 digital single-lens reflex (DSLR) cameras attached to a system of poles that suspends the cameras at a height of 4 meters with a variable camera separation of 0.6 to 0.9 m. The poles are oriented such that they do not appear in the photographs. The cameras are simultaneously remotely activated to collect stereo pairs at a resolution of 64 pixels/cm2 (pixel length is 1.2 mm). Ground control on the images is provided by pegs placed 5 meters apart, GPS positioning, and a meter-stick included in each photograph. Initial photo data gathered of a gravel bar on the Henry’s Fork of the Snake River, north of Rexburg, Idaho is sharp and readily segmented using the MatLab-based CLASTS image processing algorithm. The technique developed for imaging mid-scale features (such as cinder cones) consists of a tethered weather balloon with a gimbal that keeps the camera oriented vertically. A single DSLR camera is suspended at an elevation of approximately 45 m. The camera is operated via a radio-controlled apparatus that enables the user to view the area being photographed prior to activating the shutter. The balloon is physically moved to capture the second image of the stereo pair. Resolution of the images is 3600 pixels/m2 (pixel length is 1.6 cm). The techniques demonstrate that collecting high-resolution stereographic aerial photographs can be accomplished on a limited budget. The techniques and equipment will be used to collect repeat images for several multi-year studies, including monitoring gravel bar evolution, vector tracking of landslide and rock glacier motion, and monitoring fault scarp and cinder cone degradation.

Wheelwright, R. J.; White, W. S.; Willis, J. B.

2010-12-01

292

Features of Daily Variation in Cosmic Ray Intensity During High/Low Amplitude Events  

NASA Astrophysics Data System (ADS)

A detailed study has been conducted on the long-term changes in the diurnal, semi-diurnal and tri-diurnal anisotropy of cosmic rays in terms of the high/low amplitude anisotropic wave train events (HAE/LAE) during the period 1981--94 using the neutron monitor data from the Deep River neutron monitoring station. In all, 38 HAE and 28 LAE cases have been studied. An inter-comparison of the first three harmonics during these events has been made so as to understand the basic reason causing the occurrence of these types of events. It has been observed that the phase of diurnal anisotropy shifts towards earlier hours for HAEs; similarly, it shifts towards earlier hours as compared to the 18-Hr direction for LAEs. Semi-diurnal anisotropy phase is found to remain statistically the same for both HAE as well as for LAE. Further, tri-diurnal anisotropy phase is found to be evenly distributed for both types of events. The interplanetary magnetic field (IMF) and solar wind plasma (SWP) parameters during these events are also investigated. It has also been observed that HAE/LAEs are weakly dependent on high-speed solar wind velocity.

Mishra, Rajesh K.; Agarwal Mishra, Rekha

2005-07-01

293

Novel digital diffractive tags integrating anti-counterfeiting, tamper-evident, and high-density WORM data storage features  

NASA Astrophysics Data System (ADS)

Embossed holographic tags for security and anti-counterfeiting applications are being used by industry since many years. However, such elements are not very effective since the detector is usually the human eye, and provides therefore around 80% effective counterfeiting protection of the tag. We present a novel holographic anticounterfeiting technology which provides 99.999% protection against tag counterfeiting. Horus Technologies develops such holographic tags, which include several layers of increasingly secure optical features, from standard visual holographic patterns and OVIDs (Optical Variable Imaging Devices), to micro-holographic text, down to covert features such as encrypted high resolution holographic 1d, 2d and 3d bar codes. We also demonstrate the potential of providing anti-tamper functionality on the same tag, for packaging security (especially for medical packaging). Finally, we demonstrate that more than 1Mb/square mm of digital data can be stored and encrypted on these same tags. A specific low cost laser based reader is developed to read the various security feature of such hybrid universal holographic tags. We also present a way to change and update the encrypted data in the tag in a similar way to RFID tags. Finally, we show a cost effective technique to replicate these structures in volume by roll-to-toll embossing, and even direct by glass molding within the package itself (bottle, vial, etc,..).

Boisdur, Enrick; Kress, Bernard

2010-04-01

294

Vibrationally highly excited acetylene as studied by dispersed fluorescence and stimulated emission pumping spectroscopy: Vibrational assignment of the feature states  

SciTech Connect

The dispersed fluorescence (DF) and stimulated emission pumping (SEP) spectra of acetylene originating from single rovibronic levels of the {ital {tilde A}} {sup 1}{ital A}{sub {ital u}} state were measured with resolutions of 30 and 0.5 cm{sup {minus}1}, respectively, in order to examine the vibrational level structure of the electronic ground {ital {tilde X}} {sup 1}{Sigma}{sup +}{sub {ital g}} state. The SEP spectra revealed that the number of vibrational levels under each peak in the DF spectra increases with vibrational energy from a single vibrational level below 8000 cm{sup {minus}1} to as many as ten vibrational levels above 16 500 cm{sup {minus}1}. Taking account of the fact that a peak in the DF spectrum in the high energy region is composed of more than one level, a DF peak is called a {ital feature} {ital state} (or a feature). In the DF spectra from two {ital trans}-bending levels ({ital v}{sub 3}=2 and 3) of the {ital {tilde A}} state a total of 140 DF features between 5 700 and 21 200 cm{sup {minus}1} were detected and long progressions in the {ital trans} bend ({ital v}{sup {double prime}}{sub 4}=6 --18) and CC stretch ({ital v}{sup }{sub 2}=0 --6) were identified.

Yamanouchi, K.; Ikeda, N.; Tsuchiya, S. (Department of Pure and Applied Sciences, The University of Tokyo, Komaba, Meguroku, Tokyo (153 Japan)); Jonas, D.M.; Lundberg, J.K.; Adamson, G.W.; Field, R.W. (Department of Chemistry and George R. Harrison Spectroscopy Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts, (USA))

1991-11-01

295

Mitotic Internalization of Planar Cell Polarity Proteins Preserves Tissue Polarity  

PubMed Central

Planar cell polarity (PCP) is the collective polarization of cells along the epithelial plane, a process best understood in the terminally differentiated Drosophila wing. Proliferative tissues such as mammalian skin also display PCP, but the mechanisms that preserve tissue polarity during proliferation are not understood. During mitosis, asymmetrically-distributed PCP components risk mislocalisation or unequal inheritance, which could have profound consequences on the long-range propagation of polarity. Here, we show that when mouse epidermal basal progenitors divide, PCP components are selectively internalized into endosomes, which are inherited equally by daughter cells. Following mitosis, PCP proteins are recycled to the cell surface where asymmetry is re-established by a process reliant upon neighbouring PCP. A cytoplasmic dileucine motif governs mitotic internalization of atypical cadherin Celsr1, which recruits Vang2 and Fzd6 to endosomes. Moreover, embryos transgenic for a Celsr1 that cannot mitotically internalize, exhibit perturbed hair follicle angling, a hallmark of defective PCP. This underscores the physiological relevance and importance of this novel mechanism for regulating polarity during cell division.

Devenport, Danelle; Oristian, Daniel; Heller, Evan; Fuchs, Elaine

2011-01-01

296

Evaluating putative mechanisms of the mitotic spindle checkpoint  

PubMed Central

The mitotic spindle checkpoint halts the cell cycle until all chromosomes are attached to the mitotic spindles. Evidence suggests that the checkpoint prevents cell-cycle progression by inhibiting the activity of the APC-Cdc20 complex, but the precise mechanism underlying this inhibition is not yet known. Here, we use mathematical modeling to compare several mechanisms that could account for this inhibition. We describe the interplay between the capacities to strongly inhibit cell-cycle progression before spindle attachment on one hand and to rapidly resume cell-cycle progression once the last kinetochore is attached on the other hand. We find that inhibition that is restricted to the kinetochore region is not sufficient for supporting both requirements when realistic diffusion constants are considered. A mechanism that amplifies the checkpoint signal through autocatalyzed inhibition is also insufficient. In contrast, amplifying the signal through the release of a diffusible inhibitory complex can support reliable checkpoint function. Our results suggest that the design of the spindle checkpoint network is limited by physical constraints imposed by realistic diffusion constants and the relevant spatial and temporal dimensions where computation is performed.

Doncic, Andreas; Ben-Jacob, Eshel; Barkai, Naama

2005-01-01

297

LEM-4 promotes rapid dephosphorylation of BAF during mitotic exit  

PubMed Central

The transitions between the successive cell cycle stages depend on reversible protein phosphorylation events. The phosphorylation state of every protein within a cell is strictly determined by spatiotemporally controlled kinase and phosphatase activities. Nuclear disassembly and reassembly during open mitosis in higher eukaryotic cells is one such process that is tightly regulated by the reversible phosphorylation of key proteins. However, little is known about the regulation of these mitotic events. In particular, although kinase function during entry into mitosis is better studied, very little is known about how proteins are dephosphorylated to allow nuclear reformation at the end of mitosis. We have identified LEM?4, a conserved protein of the nuclear envelope, as an essential coordinator of kinase and phosphatase activities during mitotic exit. Inhibition of VRK?1 kinase and promotion of a PP2A phosphatase complex by LEM?4 tightly regulate the phosphorylation state of BAF, an essential player of nuclear reformation at the end of mitosis. Here I offer extended comments on the contribution of LEM?4 in the regulation of protein phosphorylation and nuclear reformation.

2013-01-01

298

LEM-4 promotes rapid dephosphorylation of BAF during mitotic exit.  

PubMed

The transitions between the successive cell cycle stages depend on reversible protein phosphorylation events. The phosphorylation state of every protein within a cell is strictly determined by spatiotemporally controlled kinase and phosphatase activities. Nuclear disassembly and reassembly during open mitosis in higher eukaryotic cells is one such process that is tightly regulated by the reversible phosphorylation of key proteins. However, little is known about the regulation of these mitotic events. In particular, although kinase function during entry into mitosis is better studied, very little is known about how proteins are dephosphorylated to allow nuclear reformation at the end of mitosis. We have identified LEM?4, a conserved protein of the nuclear envelope, as an essential coordinator of kinase and phosphatase activities during mitotic exit. Inhibition of VRK?1 kinase and promotion of a PP2A phosphatase complex by LEM?4 tightly regulate the phosphorylation state of BAF, an essential player of nuclear reformation at the end of mitosis. Here I offer extended comments on the contribution of LEM?4 in the regulation of protein phosphorylation and nuclear reformation. PMID:23211644

Gorjánácz, Mátyás

2013-01-01

299

Towards a quantitative understanding of mitotic spindle assembly and mechanics  

PubMed Central

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

Mogilner, Alex; Craig, Erin

2010-01-01

300

Analysis and modeling of mitotic spindle orientations in three dimensions.  

PubMed

The orientation of the mitotic spindle determines the relative size and position of the daughter cells and influences the asymmetric inheritance of localized cell fate determinants. The onset of mammalian neurogenesis, for example, coincides with changes in spindle orientation. To address the functional implications of this and related phenomena, precise methods for determining the orientation of the mitotic spindle in complex tissues are needed. Here, we present methodology for the analysis of spindle orientation in 3D. Our method allows statistical analysis and modeling of spindle orientation and involves two parameters for horizontal and vertical bias that can unambiguously describe the distribution of spindle orientations in an experimental sample. We find that 3D analysis leads to systematically different results from 2D analysis and, surprisingly, truly random spindle orientations do not result in equal numbers of horizontal and vertical orientations. We show that our method can describe the distribution of spindle orientation angles under different biological conditions. As an example of biological application we demonstrate that the adapter protein Inscuteable (mInsc) can actively promote vertical spindle orientation in apical progenitors during mouse neurogenesis. PMID:24381158

Jüschke, Christoph; Xie, Yunli; Postiglione, Maria Pia; Knoblich, Juergen A

2014-01-21

301

Analysis and modeling of mitotic spindle orientations in three dimensions  

PubMed Central

The orientation of the mitotic spindle determines the relative size and position of the daughter cells and influences the asymmetric inheritance of localized cell fate determinants. The onset of mammalian neurogenesis, for example, coincides with changes in spindle orientation. To address the functional implications of this and related phenomena, precise methods for determining the orientation of the mitotic spindle in complex tissues are needed. Here, we present methodology for the analysis of spindle orientation in 3D. Our method allows statistical analysis and modeling of spindle orientation and involves two parameters for horizontal and vertical bias that can unambiguously describe the distribution of spindle orientations in an experimental sample. We find that 3D analysis leads to systematically different results from 2D analysis and, surprisingly, truly random spindle orientations do not result in equal numbers of horizontal and vertical orientations. We show that our method can describe the distribution of spindle orientation angles under different biological conditions. As an example of biological application we demonstrate that the adapter protein Inscuteable (mInsc) can actively promote vertical spindle orientation in apical progenitors during mouse neurogenesis.

Juschke, Christoph; Xie, Yunli; Postiglione, Maria Pia; Knoblich, Juergen A.

2014-01-01

302

Inhibition of mitotic-specific histone phophorylation by sodium arsenite  

SciTech Connect

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.

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

303

A novel non-linear recursive filter design for extracting high rate pulse features in nuclear medicine imaging and spectroscopy.  

PubMed

Applications in imaging and spectroscopy rely on pulse processing methods for appropriate data generation. Often, the particular method utilized does not highly impact data quality, whereas in some scenarios, such as in the presence of high count rates or high frequency pulses, this issue merits extra consideration. In the present study, a new approach for pulse processing in nuclear medicine imaging and spectroscopy is introduced and evaluated. The new non-linear recursive filter (NLRF) performs nonlinear processing of the input signal and extracts the main pulse characteristics, having the powerful ability to recover pulses that would ordinarily result in pulse pile-up. The filter design defines sampling frequencies lower than the Nyquist frequency. In the literature, for systems involving NaI(Tl) detectors and photomultiplier tubes (PMTs), with a signal bandwidth considered as 15 MHz, the sampling frequency should be at least 30 MHz (the Nyquist rate), whereas in the present work, a sampling rate of 3.3 MHz was shown to yield very promising results. This was obtained by exploiting the known shape feature instead of utilizing a general sampling algorithm. The simulation and experimental results show that the proposed filter enhances count rates in spectroscopy. With this filter, the system behaves almost identically as a general pulse detection system with a dead time considerably reduced to the new sampling time (300 ns). Furthermore, because of its unique feature for determining exact event times, the method could prove very useful in time-of-flight PET imaging. PMID:22964063

Sajedi, Salar; Kamal Asl, Alireza; Ay, Mohammad R; Farahani, Mohammad H; Rahmim, Arman

2013-06-01

304

DE/ISIS conjunction comparisons of high-latitude electron density features  

NASA Technical Reports Server (NTRS)

This paper presents a comparison between the ISIS-1 and -2 topside sounder measurements of electron number density, N(e), with the in situ ion and N(e) measurements by the Langmuir probe aboard the Dynamics Explorer 2 (DE 2) during four high-latitude ISIS/DE magnetic field-aligned conjunctions. The ISIS-derived N(e) values, even at the greatest distance from the sounder, were found to agree with the Langmuir probe measurements to within about 30 percent over a density range of more than two decades on three of the four comparisons; the fourth comparison which included data with strong N(e) irregularities, showed a difference of 60 percent.

Hoegy, Walter R.; Benson, Robert F.

1988-01-01

305

Experimental investigation of primary and secondary features in high-mach-number shock-bubble interaction.  

PubMed

Experiments to study the compression and unstable evolution of an isolated soap-film bubble containing helium, subjected to a strong planar shock wave (M=2.95) in ambient nitrogen, have been performed in a vertical shock tube of square internal cross section using planar laser diagnostics. The early phase of the interaction process is dominated by the formation of a primary vortex ring due to the baroclinic source of vorticity deposited during the shock-bubble interaction, and the mass transfer from the body of the bubble to the vortex ring. The late time (long after shock interaction) study reveals the presence of a secondary baroclinic source of vorticity at high Mach number which is responsible for the formation of counterrotating secondary and tertiary vortex rings and the subsequent larger rate of elongation of the bubble. PMID:17358611

Ranjan, Devesh; Niederhaus, John; Motl, Bradley; Anderson, Mark; Oakley, Jason; Bonazza, Riccardo

2007-01-12

306

Microstructure features of high-entropy equiatomic cast AlCrFeCoNiCu alloys  

NASA Astrophysics Data System (ADS)

The structural and phase transformations that take place in the cast high-entropy equiatomic alloy AlCrFeCoNiCu after solidification, homogenizing heat treatment, and cooling have been studied. Analytical transmission microscopy, scanning electron microscopy, X-ray energy dispersive spectroscopy, and X-ray diffraction analysis were used to conduct the studies. The elastic modulus, nano-, and microhardness have been measured. The alloy decomposition has been found to occur with the precipitation of no less than six nanoscale phases with different morphologies, structures ( A2, B2, L12), and chemical compositions. All the nanophases are multicomponent solid solutions enriched with several elements, which indicates the pronounced elemental and phase nanomodulation over the alloy volume.

Ivchenko, M. V.; Pushin, V. G.; Uksusnikov, A. N.; Wanderka, N.

2013-06-01

307

Transmission electron microscopy specimen preparation perpendicular to the long axis of high aspect ratio features  

SciTech Connect

A new variation of transmission electron microscopy (TEM) specimen preparation is introduced. By thinning a tall high aspect ratio structure perpendicular to the long dimension (i.e., from the side) rather than from perpendicular to the short dimension (either the top or the bottom), it is possible to obtain a more uniformly thin TEM specimen over the entire long dimension of the structure. This article will describe the rational for this variation in specimen preparation. The necessary modifications of four different specimen preparation methods (in situ lift-out, traditional H-bar, ex situ lift-out, and tripod polishing) will be discussed and images of specimens obtained by both of these first two methods will be shown. Additional potential advantages and other applications of this specimen preparation method will be covered.

Irwin, R. B.; Anciso, A.; Jones, P. J.; Glenn, A. L.; Williams, B. L.; Sridhar, S.; Arshad, S. [TT-PEG PFA Laboratory, Texas Instruments, 13536 North Central Expressway, Mail Stop 947, Dallas, Texas 75243 (United States); MAKE Process Characterization Laboratory, Texas Instruments, 13121 TI Blvd., Mail Stop 347, Dallas, Texas 75243 (United States); Analog Technology Development, Texas Instruments, 13121 North Central Expressway, Mail Stop 364, Dallas, Texas 75243 (United States); DFAB Product Engineering, Texas Instruments, 13536 North Central Expressway, Mail Stop 947, Dallas, Texas 75243 (United States)

2009-11-15

308

General Features of Quantum Creep in High-{ital T}{sub {ital c}} Superconductors  

SciTech Connect

Measurements of the relaxation rate Q(T) of superconducting currents have been performed on a carefully selected set of {ital dirty} and {ital clean} high-T{sub c} superconductors for temperatures T down to 100 mK and magnetic fields up to 7 T. The extrapolated relaxation rates Q(0) for the dirty compounds indicate that the viscosity experienced by a tunneling vortex segment is grossly underestimated by the standard Bardeen-Stephen theory. For the clean compounds a universal value Q(0){congruent} 0.022 is found at 1 T, implying that the number of superconducting charge carriers involved in the tunneling of a vortex segment is {congruent}14 . {copyright} {ital 1998} {ital The American Physical Society}

Hoekstra, A.F.; Griessen, R.; Testa, A.M.; el Fattahi, J. [Institute COMPAS and Faculty of Physics and Astronomy, Vrije Universiteit, Amsterdam (The Netherlands)] [Institute COMPAS and Faculty of Physics and Astronomy, Vrije Universiteit, Amsterdam (The Netherlands); Testa, A.M. [ICMAT-CNR, Area della Ricerca di Roma, Rome (Italy)] [ICMAT-CNR, Area della Ricerca di Roma, Rome (Italy)

1998-05-01

309

Acinic cell carcinoma of minor salivary gland showing features of high-grade transformation  

PubMed Central

Introduction: Acinic cell carcinoma (AciCC) of salivary gland is a relatively infrequent tumor. Though known for its low-grade behavior, its unpredictable element of recurrence and malignancy should never be ignored. Case Report: A male patient with complaints of pain and swelling in the left jaw region since a year was operated based on the computed tomography (CT) and incisional biopsy report. Histopathology (routine staining, special staining, immunostaining and electron microscopy) of the excised specimen revealed it to be a variant of AciCC from minor salivary gland. Discussion: To the best of our knowledge, this is the first case of AciCC showing propensity for high-grade transformation (HGT), arising from minor salivary gland, being reported. The rarity of such variants and the importance of various investigative techniques in the diagnosis of such cases are discussed.

Ilayaraja, Vadivel; Prasad, H; Anuthama, Krishnamurthy; Sruthi, Ranganath

2014-01-01

310

Experimental Investigation of Primary and Secondary Features in High-Mach-Number Shock-Bubble Interaction  

NASA Astrophysics Data System (ADS)

Experiments to study the compression and unstable evolution of an isolated soap-film bubble containing helium, subjected to a strong planar shock wave (M=2.95) in ambient nitrogen, have been performed in a vertical shock tube of square internal cross section using planar laser diagnostics. The early phase of the interaction process is dominated by the formation of a primary vortex ring due to the baroclinic source of vorticity deposited during the shock-bubble interaction, and the mass transfer from the body of the bubble to the vortex ring. The late time (long after shock interaction) study reveals the presence of a secondary baroclinic source of vorticity at high Mach number which is responsible for the formation of counterrotating secondary and tertiary vortex rings and the subsequent larger rate of elongation of the bubble.

Ranjan, Devesh; Niederhaus, John; Motl, Bradley; Anderson, Mark; Oakley, Jason; Bonazza, Riccardo

2007-01-01

311

Features of highly structured equatorial plasma irregularities deduced from CHAMP observations  

NASA Astrophysics Data System (ADS)

In this study five years of CHAMP (Challenging Mini-satellite Payload) fluxgate magnetometer (FGM) data is used to investigate the characteristics of Equatorial Plasma Bubbles (EPBs). We filtered the FGM data by using band-passes with four different cut-off periods to get the EPBs with different maximum spatial scale sizes in the meridional plane ranging from 76-608 km. Associated with the EPB observations at about 400 km, the typical altitude of CHAMP during the year 2000-2005, we also investigate the post-sunset equatorial vertical plasma drift data from ROCSAT-1 (Republic of China Satellite 1). Since the height of the F-layer is highly correlated with the vertical plasma drift and solar flux, we sorted the ROCSAT-1 data into different groups by F10.7. From the integrated vertical drift we have estimated the post-sunset uplift of the ionosphere. By comparing the properties of EPB occurrence for different scale sizes with the global distribution of plasma vertical uplift, we have found that EPBs reaching higher altitudes are more structured than those which are sampled by CHAMP near the top side of the depleted fluxtube. Such a result is in accord with 3-D model simulations (Aveiro and Hysell, 2010). Small-scale EPB structures are observed by CHAMP when the irregularities reach apex heights of 800 km and more. Such events are encountered primarily in the Brazilian sector during the months around November, when the post-sunset vertical plasma drift is high.

Xiong, C.; Lühr, H.; Ma, S. Y.; Stolle, C.; Fejer, B. G.

2012-08-01

312

Design features of high-intensity medium-energy superconducting heavy-ion Linac.  

SciTech Connect

The proposed Rare Isotope Accelerator (RIA) requires the construction of a cw 1.4 GV superconducting (SC) linac that is capable of producing 400 kW beams of all ions from protons at 900 MeV to uranium at 400 MeV/u. The design of such a linac was outlined at the previous Linac conference. This linac will accelerate multiple-charge-states (multi-q) of the heaviest ion beams, for which the beam current is limited by ion-source performance. The linac consists of two different types of accelerating and focusing lattice: for uranium below {approx}85 MeV/u the focusing is provided by SC solenoids installed in cryostats with the SC resonators while in the high-beta section the focusing elements are located outside of the cryostats. A detailed design has been developed for the focusing-accelerating lattice of the linac. Beam dynamics studies have been performed with the goal of optimization of the linac structure in order to reduce a possible effective emittance growth of the multi-q uranium beam. A wide tuning range of the accelerating and focusing fields is required for acceleration of the variety of ions with different charge-to-mass ratios to the highest possible energy in single charge state mode. The focusing must be retuned for different ion masses to avoid resonance coupling between the transverse and longitudinal motions. Any visible impact of this coupling on the formation of beam halo must be avoided due to the high beam power.

Ostroumov, P. N.

2002-09-20

313

Why do granites stand out as high elevation features of the landscape ?  

NASA Astrophysics Data System (ADS)

We propose a simple mechanism to explain why granitic igneous intrusions, despite being denser than the rocks they usually intrude, stand out as topographic highs in the landscape. This mechanism is predicted to be far more important than hardness or erodibility variations in many cases. We derived a very simple expression for the relationship between isostatically-driven surface uplift and erosion rates as a function of surface rock density that implies that the denser the surface rocks the faster the isostatic rebound. Using a surface process model coupled to a flexural isostatic model, we show how variations in surface rock density may result in substantial differential isostatic rebound and thus surface uplift rate and topography. We demonstrate that the contribution of this isostatic effect can be distinguished from that arising from the stronger resistance of denser rocks to erosion by estimating the enhanced rate of erosion predicted by our theory through variations in cooling ages from low temperature thermochonometers. We illustrate our proposition through a large number of examples where variations in surface rock density may have led to differential uplift and topography, including various granitic intrusions, but also the exhumation of denser rocks such as basaltic intrusions or gneiss domes or the emergence of continental areas from below sea level at the transition between the subduction and collision phases at active plate margins. Predicted steady-state surface topography in an area intruded by four dense granites that appear as topographic highs. Note that the granites have the same resistance to erosion than the surrounding rocks; they are denser.

Braun, J.; Murray, K. E.; Reiners, P. W.; Simon-Labric, T.

2013-12-01

314

Resonant nanocluster technology—from optical coding and high quality security features to biochips  

NASA Astrophysics Data System (ADS)

Metal clusters deposited on a substrate and positioned at a nanometric distance from a wave-reflecting layer act as nanoresonators able to receive, store and transmit energy within the visible and infrared range of the spectrum. Among the unique effects of these metal nanocluster assemblies are high local field enhancement and nanoscale resonant behaviour driving optical absorption in the visible and infrared range of the spectrum. In these types of devices and sensors the precise nanometric assembly coupling the local field surrounding a cluster is critical for allowing resonance with other elements interacting with this field. In particular, the cluster-mirror distance or the cluster-fluorophore distance gives rise to a variety of enhancement phenomena (e.g. resonant-enhanced fluorescence, REF). Depending on the desired application this 'resonance' distance is tuned from 5 up to 500 nm. High-throughput transducers using metal cluster resonance technology are based on surface enhancement of light absorption by metal clusters (surface-enhanced absorption, SEA). These devices can be used for detection of biorecognition binding as well as structural changes in nucleic acids, proteins or any polymer. The optical property made use of in the analytical application of metal cluster films is so-called anomalous absorption. An absorbing film of clusters is positioned 10-400 nm from an electromagnetic wave-reflecting layer. At a well-defined mirror-cluster distance the reflected electromagnetic field has the same phase at the position of the absorbing cluster as the incident field. This feedback mechanism strongly enhances the effective cluster absorption coefficient. These systems are characterized by a narrow reflection minimum whose spectral position shifts sensitively with interlayer thickness, because a given cluster-mirror distance and wavelength defines the optimum phase.

Bauer, G.; Hassmann, J.; Walter, H.; Haglmüller, J.; Mayer, C.; Schalkhammer, T.

2003-12-01

315

Pathological features of invasive breast cancer associated with a high risk of local recurrence after tumour excision and radical radiotherapy.  

PubMed Central

The histological slides of 273 breast cancer patients, treated by local excision and radiotherapy and followed up for 2-6 years, were reviewed in search of factors predictive of local recurrence. Local recurrence was found to be most closely related to the combination of a high proportion of intraduct carcinoma and extensive necrosis (comedocarcinoma). This latter group of 18 patients had a local recurrence rate of 50%. These patients are of particular interest since they form a small group with readily identifiable histological features. Images fig. 2

Bulman, A. S.; Lindley, R. P.; Parsons, P.; Ellis, H.

1988-01-01

316

Dosimetric features and kinetic analysis of thermoluminescence from ultra-high molecular weight polyethylene  

NASA Astrophysics Data System (ADS)

Thermoluminescence (TL) from beta irradiated ultra-high molecular weight polyethylene has been studied for measurements between 30 and 200 °C. An aliquot studied in this work produced TL glow curves consisting of two peaks, the main peak at 88 °C and a weaker intensity peak at 148 °C for heating at 1 °C s-1 following an excitation dose of 215 Gy. The position of the main peak is poorly reproducible for heating rates of 0.2 and 0.6 °C s-1 investigated with the peak position decreasing when the sample is freshly irradiated and the TL re-measured. The said change in peak position is however less of an effect for measurements made at 1 °C s-1 with the peak position being fairly reproducible in this case. Further measurements of the dosimetric properties of ultra-high molecular weight polyethylene showed that its dose response is linear from 26 Gy to about 161 Gy but exhibits slower growth in intensity with dose from about 860 Gy after regions of sub- and supra-linearity in between. If the TL is not measured immediately after irradiation, the signal fades with the delay approximately exponentially. In addition, a number of tests including phosphorescence analysis showed the possibility that the order of kinetics might not be unique but sensitive to several factors including measurement temperature. Thus for instance, the dependence of the peak position on the stop temperature in the partial heating procedure Tm - Tstop implied first-order kinetics but analysis of the geometrical factor ?g for the same set of data gave ?g = 0.46 ± 0.03 a value corresponding to characteristics somewhat intermediate between first and second order. In comparison, the results of analysis of the phosphorescence recorded at several temperatures on the rising edge of the main peak were only in agreement for measurements at 40 °C with general-order analysis suggesting second-order kinetics apply as did TL-like transformation of the monotonic phosphorescence decay. Both results were also consistent with an additional finding that the time dependence of the isothermal decay at 40 °C was consistent with second-order kinetics. Analysis of the TL for the activation energy using the initial rise method, variable heating rate procedure, TL-like transformation of phosphorescence and the peak shape estimates, produced a self-consistent set of values equal to 0.76 ±0.05 eV, 0.66±0.03 eV, 0.77±0.06 eV and values of the order of 0.8 eV, respectively. The kinetic parameters found in this study compare favourably with literature values.

Chithambo, M. L.

2012-08-01

317

Capillary-Driven Reflow of Thin Copper Films with Submicron, High Aspect Ratio Features  

NASA Astrophysics Data System (ADS)

Conventional sputtering techniques are no longer sufficient for the fabrication of interconnects as trench widths enter the submicron regime and aspect ratios become greater than 1:1. The goal of this thesis is to investigate Cu as a potential interconnect metal for use in integrated circuit technology. Since sputtering is well established in the integrated circuit industry, we have used current sputtering technology as our deposition technique of choice. An alternative approach to modify the nonconformal deposition profiles obtained by sputtering is to reflow (planarize by capillary-driven surface diffusion) the metal film during a post-deposition anneal. In particular, reflow is performed for thin Cu films deposited on refractory metal barrier layers (Mo, Ta, and W) at temperatures <= 500^circC. With a goal of developing and understanding a post-deposition reflow process for Cu, we have studied the following topics. Chapter 1 introduces relevant current concepts in ultra-large scale integration for interconnect technology to motivate the approaches described in this thesis. Chapter 2 investigates several techniques to improve the initial Cu coverage obtained from a magnetron sputtering source. This was found to be necessary since thin Cu films agglomerate on many underlayers. Chapter 3 describes an investigation of the atomic transport mechanism during reflow of Cu films, to understand the kinetics of reflow and measure the appropriate kinetic constants. Extensive transmission electron microscope (TEM) work was done to examine reflowed profiles and to relate the extent of reflow to the microstructure of the Cu films. Hot-stage TEM experiments were performed to observe dynamically the reflow of a very low aspect ratio film. Chapter 4 develops a finite-element model to study surface diffusion mediated reflow in high aspect ratio trenches. We have considered (i) reflow of typical continuum, as-deposited profiles from a magnetron sputtering source, (ii) reflow of continuum profiles including an anisotropic surface energy and (iii) reflow with the inclusion of grain boundaries. We also discuss some limitations of a post-deposition reflow process, and we make recommendations to facilitate the ability to reflow Cu in high aspect ratio trenches. Finally, Chapter 5 examines a microwave annealing technique to reflow Cu films.

Brain, Ruth Amy

318

Freeform mirror fabrication and metrology using a high performance test CGH and advanced alignment features  

NASA Astrophysics Data System (ADS)

The metrology of mirrors with an off-axis aspheric or freeform shape can be based on optical testing using a Computer Generated Hologram as wavefront matching element in an interferometric setup. Since the setup can be understood as optical system consisting of multiple elements with six degrees of freedom each, the accuracy strongly depends on the alignment of the surface under test with respect to the transmission element of the interferometer and the micro optics of the CGH. A novel alignment approach for the relative positioning of the mirror and CGH in six degrees of freedom is reported. In the presented work, a proper alignment is achieved by illuminating alignment elements outside the Clear Aperture (CA) of the optical surface with the help of auxiliary holograms next to the test CGH on the substrate. The peripheral holograms on the CGH substrate are used to generate additional phase maps in the interferogram, that indicate positioning errors. Since the reference spheres represent the coordinate system of the mirror and are measured in the same precision as the optical surface, the registration and shape has to be appropriate to embody the mirrors coordinate system. The alignment elements on the mirror body are diamond machined using freeform turning or micro milling processes in the same machine setup used for the mirror manufacturing. The differences between the turning and milling of alignment lenses is discussed. The novel approach is applied to correct the shape error of a freeform mirror using ultra precision machining. The absolute measurement of the quality of freeform mirror shapes including tilt and optical power is possible using the presented alignment concept. For a better understanding, different metrology methods for aspheres and freeforms are reviewed. To verify the novel method of alignment and the measurement results, the freeform surface is also characterized using ultra high accuracy 2½D profilometry. The results of the different techniques for the absolute measurement of freeforms are compared.

Scheiding, Sebastian; Beier, Matthias; Zeitner, Uwe-Detlef; Risse, Stefan; Gebhardt, Andreas

2013-03-01

319

High Susceptibility for Enterovirus Infection and Virus Excretion Features in Tunisian Patients with Primary Immunodeficiencies  

PubMed Central

To estimate the susceptibility to enterovirus infection and the frequency of long-term poliovirus excreters in Tunisian patients with primary immunodeficiencies (PIDs), enteroviruses were assessed in stool specimens of 82 patients with humoral, combined, and other PIDs. Isolated viruses were typed and intratyped by standard molecular techniques, and the whole VP1 region of poliovirus isolates was sequenced. Polioviruses were detected in 6 patients; all isolates were vaccine related. Five patients rapidly stopped excretion; one excreted a poliovirus type 1 isolate for several months, and the isolate accumulated up to 14 mutations in the VP1 region. Nonpolio enteroviruses were identified in 6 patients; 4 of them kept excreting the same strain for more than 6 months. The rate of enterovirus infection was 13.4% of the PID patients and 20.7% of those with an IgG defect; it greatly exceeded the rates generally found in Tunisian supposed-immunocompetent individuals (4.1% during the study period; P = 0.001 and P < 0.0001, respectively). Interestingly, patients with combined immunodeficiencies were at a higher risk for enterovirus infection than those with an exclusively B cell defect. A major histocompatibility complex (MHC) class II antigen expression defect was found in 54% of enterovirus-positive patients and in the unique long-term poliovirus excreter. The study results also suggest that substitutive immunoglobulin therapy may help clearance of a poliovirus infection and that most PID patients have the ability to stop poliovirus excretion within a limited period. However, the high susceptibility of these patients to enterovirus infection reinforces the need for enhanced surveillance of these patients until the use of oral poliovirus vaccine (OPV) is stopped.

Driss, Nadia; Ben-Mustapha, Imen; Mellouli, Fethi; Ben Yahia, Ahlem; Touzi, Henda; Bejaoui, Mohamed; Ben Ghorbel, Mohamed; Barbouche, Mohamed-Ridha

2012-01-01

320

EFFECTS OF GIBBERELLIN, KINETIN, THIOUREA, AND PHOTOMORPHOGENIC RADIATION ON MITOTIC ACTIVITY IN DORMANT LETTUCE SEED  

Microsoft Academic Search

The effects of several germination-stimulating agents on mitotic ; activity in radicles of nongerminated lettuce seeds were studied using conditions ; near the upper limits of temperatures permitting germination. Under appropriate ; conditions where gibberellin, kinetin, thiourea, and red light could stimulate ; germination, only kinetin stimulated mitotic activity. Kinetin can be considered ; a true cell division factor in

A. H. Haber; H. J. Luippold

1960-01-01

321

MIX1: An Essential Component of the C. elegans Mitotic Machinery Executes X Chromosome Dosage Compensation  

Microsoft Academic Search

We show that a functional component of the C. elegans mitotic machinery regulates X chromosome gene expression. This protein, MIX-1, is a member of the dosage compensation complex that associates specifically with hermaphrodite X chromosomes to reduce their gene expression during interphase. MIX-1 also associates with all mitotic chromosomes to ensure their proper segregation. Both dosage compensation and mitosis are

Jason D Lieb; Michael R Albrecht; Pao-Tien Chuang; Barbara J Meyer

1998-01-01

322

GeoNet: Nonlinear filtering and geodesic minimization principles for geomorphic feature extraction from high resolution topographic data  

NASA Astrophysics Data System (ADS)

The detection of channel networks and the localization of channel heads from digital terrain model (DTM) data are fundamental to the accurate modeling of water, sediment, and other environmental fluxes in a watershed. With the availability of high resolution topographic data obtained by airborne laser mapping, the direct detection of geomorphic features such as channels is now possible, instead of indirect inference using derived quantities such as slope and drainage area. At the same time, the impressive resolution of lidar data comes with a price: new tools are needed for the automatic and objective extraction of geomorphic features from the enormous amount of information contained in such DTMs. The GeoNet software package carries out the automatic extraction of channel networks, channel heads and channel morphology from high-resolution topographic data. Pre-processing of the data is performed through nonlinear filtering, via partial differential equations, which removes small scale variability while enhancing features of interest. The form of this filtering is such that it behaves as linear diffusion at low elevation gradients, while it arrests diffusion as the gradients become large. Channel detection is performed by solving an eikonal equation through the fast marching algorithm. Channels are thus detected as curves of minimal cost, or geodesics, where the cost is defined in physically meaningful terms using local geomorphic attributes derived from the DTM. GeoNet is now at its third release as free software. This talk will focus on the technical aspects of the software and in particular on the new improved performance of its latest release.

Passalacqua, P.; Stark, C. P.; Sangireddy, H.

2011-12-01

323

The Role of Calcium in the Mitotic Stimulation of Rat Thymocytes by Detergents, Agmatine and Poly-L-Lysine.  

National Technical Information Service (NTIS)

Low concentrations of the detergents cetyltrimethyl ammonium bromide, dodecyl sodium sulphate, and Triton X-100 stimulate mitotic activity in rat thymocyte populations maintained in vitro. These compounds have no mitotic effect on cells maintained in calc...

J. F. Whitfield A. D. Perris R. Youdale

1968-01-01

324

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

PubMed Central

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

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

2012-01-01

325

Preparing a cell for nuclear envelope breakdown: Spatio-temporal control of phosphorylation during mitotic entry.  

PubMed

Chromosome segregation requires the ordered separation of the newly replicated chromosomes between the two daughter cells. In most cells, this requires nuclear envelope (NE) disassembly during mitotic entry and its reformation at mitotic exit. Nuclear envelope breakdown (NEB) results in the mixture of two cellular compartments. This process is controlled through phosphorylation of multiple targets by cyclin-dependent kinase 1 (Cdk1)-cyclin B complexes as well as other mitotic enzymes. Experimental evidence also suggests that nucleo-cytoplasmic transport of critical cell cycle regulators such as Cdk1-cyclin B complexes or Greatwall, a kinase responsible for the inactivation of PP2A phosphatases, plays a major role in maintaining the boost of mitotic phosphorylation thus preventing the potential mitotic collapse derived from NEB. These data suggest the relevance of nucleo-cytoplasmic transport not only to communicate cytoplasmic and nuclear compartments during interphase, but also to prepare cells for the mixture of these two compartments during mitosis. PMID:24889070

Alvarez-Fernández, Mónica; Malumbres, Marcos

2014-08-01

326

Beyond Taxanes: A Review of Novel Agents That Target Mitotic Tubulin and Microtubules, Kinases, and Kinesins  

PubMed Central

Until recently, development of chemotherapeutic agents that target mitosis has centered on inhibiting the mitotic spindle through interactions with microtubules. The taxanes, while significantly advancing the treatment of many types of cancer, suffer from problems of hematopoeitic and neurologic toxicities, development of resistance, and an inconvenient formulation. Novel microtubule inhibitors currently in clinical testing and in clinical use have the main advantage of overcoming resistance. Still, they have side effects related to the inhibition of microtubules in normal host cells. Novel anti-mitotics, which target the mitotic spindle through interactions with non-microtubule mitotic mediators like mitotic kinases and kinesins, have been identified and are now in clinical testing. They offer the prospect of surmounting more of the problems inherent with taxanes and the hope of improving upon their broad antitumor efficacy. This review will concentrate on novel agents in later clinical development that target both the spindle microtubule and non-microtubule constituents of mitosis.

Harrison, Michael R.; Holen, Kyle D.; Liu, Glenn

2010-01-01

327

Mitotic rate in melanoma: prognostic value of immunostaining and computer-assisted image analysis  

PubMed Central

The prognostic value of mitotic rate in melanoma is increasingly recognized, particularly in thin melanoma where the presence or absence of a single mitosis/mm2 can change staging from T1a to T1b. Still, accurate mitotic rate calculation (mitoses/mm2) on hematoxylin and eosin (H&E)-stained sections can be challenging. Anti-monoclonal mitotic protein-2 (MPM-2) and anti-phosphohistone H3 (PHH3) are two antibodies reported to be more mitosis-specific than other markers of proliferation such as Ki-67. We used light microscopy and computer-assisted image analysis software to quantify MPM-2 and PHH3 staining in melanoma. We then compared mitotic rates by each method to conventional H&E-based mitotic rate for correlation with clinical outcomes. Our study included primary tissues from 190 non-consecutive cutaneous melanoma patients who were prospectively enrolled at New York University Langone Medical Center with information on age, gender, and primary tumor characteristics. Mitotic rate was quantified manually by light microscopy of corresponding H&E, MPM-2, and PHH3-stained sections. Computer-assisted image analysis was then used to quantify immunolabeled mitoses on the previously examined PHH3 and MPM-2 slides. We then analyzed the association between mitotic rate and both progression-free and melanoma-specific survival. Univariate analysis of PHH3 found significant correlation between increased PHH3 mitotic rate and decreased progression-free survival (P=0.04). Computer-assisted image analysis enhanced the correlation of PHH3 mitotic rate with progression-free survival (P=0.02). Regardless of detection method, neither MPM-2 nor PHH3 offered significant advantage over conventional H&E determination of mitotic rate.

Hale, Christopher S.; Qian, Meng; Ma, Michelle W.; Scanlon, Patrick; Berman, Russell S.; Shapiro, Richard L.; Pavlick, Anna C.; Shao, Yongzhao; Polsky, David; Osman, Iman; Darvishian, Farbod

2012-01-01

328

IC261, a specific inhibitor of the protein kinases casein kinase 1-delta and -epsilon, triggers the mitotic checkpoint and induces p53-dependent postmitotic effects.  

PubMed

The p53-targeted kinases casein kinase 1delta (CK1delta) and casein kinase 1epsilon (CK1epsilon) have been proposed to be involved in regulating DNA repair and chromosomal segregation. Recently, we showed that CK1delta localizes to the spindle apparatus and the centrosomes in cells with mitotic failure caused by DNA-damage prior to mitotic entry. We provide here evidence that 3-[(2,4,6-trimethoxyphenyl)methylidenyl]-indolin-2-one (IC261), a novel inhibitor of CK1delta and CK1epsilon, triggers the mitotic checkpoint control. At low micromolar concentrations IC261 inhibits cytokinesis causing a transient mitotic arrest. Cells containing active p53 arrest in the postmitotic G1 phase by blockage of entry into the S phase. Cells with non-functional p53 undergo postmitotic replication developing an 8N DNA content. The increase of DNA content is accompanied by a high amount of micronucleated and apoptotic cells. Immunfluorescence images show that at low concentrations IC261 leads to centrosome amplification causing multipolar mitosis. Our data are consistent with a role for CK1delta and CK1epsilon isoforms in regulating key aspects of cell division, possibly through the regulation of centrosome or spindle function during mitosis. PMID:11103931

Behrend, L; Milne, D M; Stöter, M; Deppert, W; Campbell, L E; Meek, D W; Knippschild, U

2000-11-01

329

Positron annihilation spectroscopy and small angle neutron scattering characterization of nanostructural features in high-nickel model reactor pressure vessel steels  

Microsoft Academic Search

Irradiation embrittlement in nuclear reactor pressure vessel steels results from the hardening by a high number density of nanometer scale features. In steels with more than ?0.10% Cu, the dominant features are often Cu-rich precipitates typically alloyed with Mn, Ni and Si. At low-Cu and low-to-intermediate Ni levels, so-called matrix hardening features are believed to be vacancy-solute cluster complexes, or

Stephen C. Glade; Brian D. Wirth; G. Robert Odette; P. Asoka-Kumar

2006-01-01

330

Positron annihilation spectroscopy and small angle neutron scattering characterization of nanostructural features in high-nickel model reactor pressure vessel steels  

Microsoft Academic Search

Irradiation embrittlement in nuclear reactor pressure vessel steels results from the hardening by a high number density of nanometer scale features. In steels with more than ≈0.10% Cu, the dominant features are often Cu-rich precipitates typically alloyed with Mn, Ni and Si. At low-Cu and low-to-intermediate Ni levels, so-called matrix hardening features are believed to be vacancy-solute cluster complexes, or

Stephen C. Glade; Brian D. Wirth; G. Robert Odette; P. Asoka-Kumar

2006-01-01

331

A Genetic Map of DICTYOSTELIUM DISCOIDEUM Based on Mitotic Recombination  

PubMed Central

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 groups studied. The mating-type locus, matA, has been located in the tsgE-sprA interval on linkage group I on the basis of studies on diploids formed between strains of opposite mating type that have escaped from vegetative incompatibility.

Welker, Dennis L.; Williams, Keith L.

1982-01-01

332

THE NUCLEOLI IN MITOTIC DIVISIONS OF MAMMALIAN CELLS IN VITRO  

PubMed Central

In a number of mammalian cell strains nucleoli persisted through mitosis. This phenomenon was especially pronounced in several cell lines derived from Chinese hamster tissues. All the methods employed, including radioautography with tritiated uridine, cytochemical stains (methyl green-pyronin and azure B), fluorescent microscopy (coriphosphine O), ribonuclease digestion, and electron microscopy, demonstrated that the bodies identified as persistent nucleoli in the mitotic stages had the same characteristics as did the nucleoli in the interphase. Persistent nucleoli may attach to the chromosomes or may be free in the cytoplasm. In cells where no persistent nucleoli as such were noted, nucleolar material was observed to attach to the chromosomes in shapeless masses which moved with the chromosomes during anaphase. At least a portion of the nucleolar material was included in the daughter nuclei, presumably for immediate use for protein synthesis after cell division.

Hsu, T. C.; Arrighi, Frances E.; Klevecz, Robert R.; Brinkley, B. R.

1965-01-01

333

Mitotic wnt signaling promotes protein stabilization and regulates cell size.  

PubMed

Canonical Wnt signaling is thought to regulate cell behavior mainly by inducing ?-catenin-dependent transcription of target genes. In proliferating cells Wnt signaling peaks in the G2/M phase of the cell cycle, but the significance of this "mitotic Wnt signaling" is unclear. Here we introduce Wnt-dependent stabilization of proteins (Wnt/STOP), which is independent of ?-catenin and peaks during mitosis. We show that Wnt/STOP plays a critical role in protecting proteins, including c-MYC, from GSK3-dependent polyubiquitination and degradation. Wnt/STOP signaling increases cellular protein levels and cell size. Wnt/STOP, rather than ?-catenin signaling, is the dominant mode of Wnt signaling in several cancer cell lines, where it is required for cell growth. We propose that Wnt/STOP signaling slows down protein degradation as cells prepare to divide. PMID:24837680

Acebron, Sergio P; Karaulanov, Emil; Berger, Birgit S; Huang, Ya-Lin; Niehrs, Christof

2014-05-22

334

Mitotic Exit and Separation of Mother and Daughter Cells  

PubMed Central

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

Weiss, Eric L.

2012-01-01

335

High-resolution PFPE-based molding techniques for nanofabrication of high-pattern density, sub-20 nm features: a fundamental materials approach.  

PubMed

Several perfluoropolyether (PFPE)-based elastomers for high-resolution replica molding applications are explored. The modulus of the elastomeric materials was increased through synthetic and additive approaches while maintaining relatively low surface tension values (<25 mN/m). Using large area (>4 in.(2)) master templates, we experimentally show the relationship between mold resolution and material properties such as modulus and surface tension for materials used in this study. A composite mold approach was used to form flexible molds out of stiff, high modulus materials that allow for replication of sub-20 nm post structures. Sub-100 nm line grating master templates, formed using e-beam lithography, were used to determine the experimental stability of the molding materials. It was observed that as the feature spacing decreased, high modulus PFPE tetramethacrylate (TMA) composite molds were able to effectively replicate the nanograting structures without cracking or tear-out defects that typically occur with high modulus elastomers. PMID:20178369

Williams, Stuart S; Retterer, Scott; Lopez, Rene; Ruiz, Ricardo; Samulski, Edward T; DeSimone, Joseph M

2010-04-14

336

High-Resolution PFPE-based Molding Techniques for Nanofabrication of High-Pattern Density, Sub-20nm Features: A Fundamental Materials Approach  

SciTech Connect

Several perfluoropolyether (PFPE)-based elastomers for high-resolution replica molding applications are explored. The modulus of the elastomeric materials was increased through synthetic and additive approaches while maintaining relatively low surface tension values (<25 mN/m). Using large area (>4 in.{sup 2}) master templates, we experimentally show the relationship between mold resolution and material properties such as modulus and surface tension for materials used in this study. A composite mold approach was used to form flexible molds out of stiff, high modulus materials that allow for replication of sub-20 nm post structures. Sub-100 nm line grating master templates, formed using e-beam lithography, were used to determine the experimental stability of the molding materials. It was observed that as the feature spacing decreased, high modulus PFPE tetramethacrylate (TMA) composite molds were able to effectively replicate the nanograting structures without cracking or tear-out defects that typically occur with high modulus elastomers.

Williams, Stuart S.; Retterer, Scott; Lopez, Rene; Ruiz, Ricardo; Samulski, Edward T.; DeSimone, Joseph M.

2010-01-01

337

Chronic sputum production: correlations between clinical features and findings on high resolution computed tomographic scanning of the chest.  

PubMed Central

BACKGROUND: There are few published data on the correlation between the clinical findings in subjects with chronic sputum production and the appearances on high resolution computed tomographic (HRCT) scans of the chest. METHODS: HRCT scanning of the chest was performed on 40 subjects with chronic sputum production. Three readers independently reported the scans for the presence or absence of bronchiectasis and the extent of bronchiectasis on the basis of the percentage of involved bronchi in each lobe. Relationships were sought between these findings and the clinical history, physical examination, and laboratory investigations. RESULTS: HRCT scanning showed that 27 subjects had bronchiectasis. Of the clinical features only the continual production of purulent sputum and childhood pertussis were associated with bronchiectasis. There was a positive correlation between the extent of bronchiectasis and dyspnoea, and a negative correlation with forced expiratory volume in one second but not with forced vital capacity. CONCLUSIONS: These results indicate that, in subjects with chronic sputum production, only a few clinical features show any correlation with the presence or extent of bronchiectasis as visualised on HRCT scans.

Smith, I. E.; Jurriaans, E.; Diederich, S.; Ali, N.; Shneerson, J. M.; Flower, C. D.

1996-01-01

338

Epidemiological features of hepatitis B and C infection in a high risk population: results of screening programs  

PubMed Central

Aim The aim of this study was to report the epidemiological features of HBV & HCV infection in an Iranian high risk population. Background Hepatitis B and hepatitis C infections are worldwide serious public health problems. Iran has an intermediate prevalence of infection and a screening program was started in 2010 among high risk individuals. Patients and methods This cross-sectional study was conducted on 4455 new patients during two past years. Demographic information, age, gender, occupational status, medical history, history of vaccination against HBV, high risk exposure and laboratory findings were collected for each patient. Then distribution of demographic and risk factors was evaluated in each type of hepatitis. Results The mean age of patients was 45.6±17.3 years. More than two-thirds of the diagnosed cases were infected with HBV. 74% of patients were carriers of hepatitis virus. 60% of patients had no symptoms at diagnosis. Illicit intravenous drug use was most common high risk exposure in patients under study (n=366, 8.2%). High risk behaviors including illicit intravenous drug use and unprotected sex were relatively higher in patients infected with hepatitis C compared to patients with hepatitis B infection. Conclusion Findings of this study suggest that illicit intravenous drug use, contact with an infected household member and unprotected sex are the most common high risk exposure in Iranian patients infected with viral hepatitis. Therefore, preventive strategies such as health education, vaccination and screening programs should be directed to these groups. The results also show that a majority of patients have no symptoms at the time of diagnosis, therefore periodic screening tests in high risk groups is required.

Noori, Simin; Gol-Mohamadi, Ali; Sarbazi, Mohammad Reza; Farsar, Ahmad Reza

2013-01-01

339

Mapping the Organization of Axis of Motion Selective Features in Human Area MT Using High-Field fMRI  

PubMed Central

Functional magnetic resonance imaging (fMRI) at high magnetic fields has made it possible to investigate the columnar organization of the human brain in vivo with high degrees of accuracy and sensitivity. Until now, these results have been limited to the organization principles of early visual cortex (V1). While the middle temporal area (MT) has been the first identified extra-striate visual area shown to exhibit a columnar organization in monkeys, evidence of MT's columnar response properties and topographic layout in humans has remained elusive. Research using various approaches suggests similar response properties as in monkeys but failed to provide direct evidence for direction or axis of motion selectivity in human area MT. By combining state of the art pulse sequence design, high spatial resolution in all three dimensions (0.8 mm isotropic), optimized coil design, ultrahigh field magnets (7 Tesla) and novel high resolution cortical grid sampling analysis tools, we provide the first direct evidence for large-scale axis of motion selective feature organization in human area MT closely matching predictions from topographic columnar-level simulations.

De Martino, Federico; van de Moortele, Pierre-Francois; Feinberg, David; Adriany, Gregor; Chaimow, Denis; Shmuel, Amir; Ugurbil, Kamil; Yacoub, Essa

2011-01-01

340

Partial inhibition of Cdk1 in G 2 phase overrides the SAC and decouples mitotic events.  

PubMed

Entry and progression through mitosis has traditionally been linked directly to the activity of cyclin-dependent kinase 1 (Cdk1). In this study we utilized low doses of the Cdk1-specific inhibitor, RO3306 from early G 2 phase onwards. Addition of low doses of RO3306 in G 2 phase induced minor chromosome congression and segregation defects. In contrast, mild doses of RO3306 during G 2 phase resulted in cells entering an aberrant mitosis, with cells fragmenting centrosomes and failing to fully disassemble the nuclear envelope. Cells often underwent cytokinesis and metaphase simultaneously, despite the presence of an active spindle assembly checkpoint, which prevented degradation of cyclin B1 and securin, resulting in the random partitioning of whole chromosomes. This highly aberrant mitosis produced a significant increase in the proportion of viable polyploid cells present up to 3 days post-treatment. Furthermore, cells treated with medium doses of RO3306 were only able to reach the threshold of Cdk1 substrate phosphorylation required to initiate nuclear envelope breakdown, but failed to reach the levels of phosphorylation required to correctly complete pro-metaphase. Treatment with low doses of Okadaic acid, which primarily inhibits PP2A, rescued the mitotic defects and increased the number of cells that completed a normal mitosis. This supports the current model that PP2A is the primary phosphatase that counterbalances the activity of Cdk1 during mitosis. Taken together these results show that continuous and subtle disruption of Cdk1 activity from G 2 phase onwards has deleterious consequences on mitotic progression by disrupting the balance between Cdk1 and PP2A. PMID:24626186

McCloy, Rachael A; Rogers, Samuel; Caldon, C Elizabeth; Lorca, Thierry; Castro, Anna; Burgess, Andrew

2014-05-01

341

High-grade gliomas in children.  

PubMed

High-grade gliomas (HGGs) are malignant tumors and typically include glioblastoma multiforme and anaplastic astrocytoma subtypes. Brainstem gliomas and ependymomas are separate entities with respect to clinical presentation, treatment, prognosis, and outcome in comparison with supratentorial HGGs. In children, these tumors account for 3% to 7% of newly diagnosed brain tumors and 20% of all diagnoses of pediatric supratentorial brain tumors. These neoplasms are highly proliferative and mitotically active and of glial origin. This article reviews clinical, diagnostic, and pathologic features of HGG and current treatments and potential future therapies specific to pediatric patients with HGGs. PMID:22748663

Cage, Tene A; Mueller, Sabine; Haas-Kogan, Daphne; Gupta, Nalin

2012-07-01

342

High sensitivity optical fiber temperature sensor based on the temperature cross-sensitivity feature of RI-sensitive device  

NASA Astrophysics Data System (ADS)

Considerable part of optical fiber refractive index (RI) sensors suffer from the drawback of cross-sensitivity to temperature because of the thermo-optic effect of materials. In this paper, we propose a straightforward method to utilize the temperature cross-sensitivity feature of an optical fiber RI-sensitive device and thus got a high sensitivity temperature sensor. The sensor consists of a single mode fiber-multimode fiber core(MMFC)-single mode fiber structural refractometer encapsulated into a deionized water-filled cylindrical aluminum alloy shell. Benefiting from the larger thermo-optic coefficient difference between water and MMFC compared with the general cladding and core, the wavelength of transmitted spectrum presents enhanced shift when the ambient temperature change and thus get a higher temperature sensitivity. Experimental results show that the enhanced temperature sensitivity is about 358 pm/°C, which is almost 30 times that of the inherent temperature sensitivity.

Sun, Hao; Hu, Manli; Rong, Qiangzhou; Du, Yanying; Yang, Hangzhou; Qiao, Xueguang

2014-07-01

343

Analogues to features and processes of a high-level radioactive waste repository proposed for Yucca Mountain, Nevada  

USGS Publications Warehouse

Natural analogues are defined for this report as naturally occurring or anthropogenic systems in which processes similar to those expected to occur in a nuclear waste repository are thought to have taken place over time periods of decades to millennia and on spatial scales as much as tens of kilometers. Analogues provide an important temporal and spatial dimension that cannot be tested by laboratory or field-scale experiments. Analogues provide one of the multiple lines of evidence intended to increase confidence in the safe geologic disposal of high-level radioactive waste. Although the work in this report was completed specifically for Yucca Mountain, Nevada, as the proposed geologic repository for high-level radioactive waste under the U.S. Nuclear Waste Policy Act, the applicability of the science, analyses, and interpretations is not limited to a specific site. Natural and anthropogenic analogues have provided and can continue to provide value in understanding features and processes of importance across a wide variety of topics in addressing the challenges of geologic isolation of radioactive waste and also as a contribution to scientific investigations unrelated to waste disposal. Isolation of radioactive waste at a mined geologic repository would be through a combination of natural features and engineered barriers. In this report we examine analogues to many of the various components of the Yucca Mountain system, including the preservation of materials in unsaturated environments, flow of water through unsaturated volcanic tuff, seepage into repository drifts, repository drift stability, stability and alteration of waste forms and components of the engineered barrier system, and transport of radionuclides through unsaturated and saturated rock zones.

Simmons, Ardyth M., Los Alamos National Laboratory, Los Alamos, New Mexico; Stuckless, John S., U.S. Geological Survey, Denver, Colorado; with a Foreword by Abraham Van Luik, U.S. Department of Energy

2010-01-01

344

Control of high oceanic features and subduction channel on earthquake ruptures along the Chile-Peru subduction zone  

NASA Astrophysics Data System (ADS)

We discuss the earthquake rupture behavior along the Chile-Peru subduction zone in terms of the buoyancy of the subducting high oceanic features (HOF's), and the effect of the interplay between HOF and subduction channel thickness on the degree of interplate coupling. We show a strong relation between subduction of HOF's and earthquake rupture segments along the Chile-Peru margin, elucidating how these subducting features play a key role in seismic segmentation. Within this context, the extra increase of normal stress at the subduction interface is strongly controlled by the buoyancy of HOF's which is likely caused by crustal thickening and mantle serpentinization beneath hotspot ridges and fracture zones, respectively. Buoyancy of HOF's provide an increase in normal stress estimated to be as high as 10-50 MPa. This significant increase of normal stress will enhance seismic coupling across the subduction interface and hence will affect the seismicity. In particular, several large earthquakes (Mw ? 7.5) have occurred in regions characterized by subduction of HOF's including fracture zones (e.g., Nazca, Challenger and Mocha), hotspot ridges (e.g., Nazca, Iquique, and Juan Fernández) and the active Nazca-Antarctic spreading center. For instance, the giant 1960 earthquake (Mw = 9.5) is coincident with the linear projections of the Mocha Fracture Zone and the buoyant Chile Rise, while the active seismic gap of north Chile spatially correlates with the subduction of the Iquique Ridge. Further comparison of rupture characteristics of large underthrusting earthquakes and the locations of subducting features provide evidence that HOF's control earthquake rupture acting as both asperities and barriers. This dual behavior can be partially controlled by the subduction channel thickness. A thick subduction channel smooths the degree of coupling caused by the subducted HOF which allows lateral earthquake rupture propagation. This may explain why the 1960 rupture propagates through six major fracture zones, and ceased near the Mocha Fracture Zone in the north and at the Chile Rise in the south (regions characterized by a thin subduction channel). In addition, the thin subduction channel (north of the Juan Fernández Ridge) reflects a heterogeneous frictional behavior of the subduction interface which appears to be mainly controlled by the subduction of HOF's.

Contreras-Reyes, Eduardo; Carrizo, Daniel

2011-05-01

345

Contribution of High Resolution Microwave and Optical Remote Sensing Observations in Detecting and Monitoring Ocean Coastal Features  

NASA Astrophysics Data System (ADS)

Synthetic Aperture Radar SAR satellite sensors have demonstrated their ability to observe ocean features related to dynamical processes Because of the high resolution of available SAR sensors circulation details and small-scale processes can be detected that are not observable by other sensors more frequently used for ocean research such as the NOAA AVHRR and the ORBVIEW2 SeaWiFS In contrast to these LANDSAT-TM thermal and optical channels can be used to observe sea surface temperatures surface layer ocean color upwelled radiance as well as sun glint reflected radiance patterns of surface roughness at a spatial resolution comparable to that of SAR Several examples of TM images obtained in 1997-2003 over the Argentine coastal ocean region where selected from an extensive data set These images were analyzed and compared with a series of SAR images acquired over the same region by the ERS satellites and in some cases near coincident with the TM data This time period allowed the examination of the seasonal cycles as well as interesting episodic events of different ocean processes including currents fronts upwellings algal blooms eddies internal waves and bathymetry signatures Due in situ observations are scarce over this region some of these processes have been documented for first time helping to improve our understanding of some dynamical and biological aspects Therefore it can be concluded that high resolution optical thermal and microwave data have the ability of providing consistent and complementary high-resolution

Gagliardini, D. A.

346

Alterations in the mitotic index of Allium cepa induced by infusions of Pluchea sagittalis submitted to three different cultivation systems.  

PubMed

We evaluated the antiproliferative effect of infusions from Pluchea sagittalis using the Allium cepa test. Infusions in three concentrations (2.5, 5, and 25 g dm-3) of leaves cultivated in three environments (in vitro, acclimatized growth chamber, and field) were used. Six onion bulbs were used for each of the eight treatments, and the mitotic index was obtained from 6000 cells per treatment. In conclusion, leaf infusions of P. sagittalis cultivated in the field have a high antiproliferative activity, as well as the cultivation system influences the antiproliferative potential. PMID:21152759

Rossato, Liana V; Tedesco, Solange B; Laughinghouse, Haywood D; Farias, Júlia G; Nicoloso, Fernando T

2010-12-01

347

Role of High-Level and Low-level Features in Semi-Automated Retrieval and Generation of Multimedia Presentations. Information Systems.  

National Technical Information Service (NTIS)

In this article we argue that for the automatic generation of adaptive multimedia presentations we are in need of expandable, adaptable style descriptions which provide both high-level conceptual and low-level feature extraction information. Only the comb...

E. J. Pauwels F. M. Nack H. L. Hardman M. A. Windhouwer M. W. J. H. Huijberts

2001-01-01

348

Prognostic factors in gastric cancer: the value of vascular invasion, mitotic rate and lymphoplasmacytic infiltration.  

PubMed

A retrospective analysis of 321 gastric cancer patients was made to assess the prognostic value of TNM classification, tumour differentiation, Laurén classification, proliferative rate, inflammatory reaction and tumour invasion in vascular or neural structures of the gastric wall. The TNM classification showed the strongest correlation with survival in univariate and multivariate analyses (P < 0.0001). The invasion in lymphatic or vascular system and Laurén classification were also independent prognosticators in multivariate analysis (P < 0.05). In univariate analysis, the WHO-grade, the size and the location of the tumour and perinueral invasion were significant prognostic factors (P < 0.01), as were the infiltration of lymphocytes and plasma cells in the tumour (P < 0.05). On the other hand, the mitotic indices reflecting the proliferative activity of the tumour cells showed no significant correlation with the prognosis. The results indicate that the prognostic power of the TNM classification can be further increased by assessment of the above special histological features in gastric cancer. PMID:8795580

Setälä, L P; Kosma, V M; Marin, S; Lipponen, P K; Eskelinen, M J; Syrjänen, K J; Alhava, E M

1996-09-01

349

Lip-Reading Aids Word Recognition Most in Moderate Noise: A Bayesian Explanation Using High-Dimensional Feature Space  

PubMed Central

Watching a speaker's facial movements can dramatically enhance our ability to comprehend words, especially in noisy environments. From a general doctrine of combining information from different sensory modalities (the principle of inverse effectiveness), one would expect that the visual signals would be most effective at the highest levels of auditory noise. In contrast, we find, in accord with a recent paper, that visual information improves performance more at intermediate levels of auditory noise than at the highest levels, and we show that a novel visual stimulus containing only temporal information does the same. We present a Bayesian model of optimal cue integration that can explain these conflicts. In this model, words are regarded as points in a multidimensional space and word recognition is a probabilistic inference process. When the dimensionality of the feature space is low, the Bayesian model predicts inverse effectiveness; when the dimensionality is high, the enhancement is maximal at intermediate auditory noise levels. When the auditory and visual stimuli differ slightly in high noise, the model makes a counterintuitive prediction: as sound quality increases, the proportion of reported words corresponding to the visual stimulus should first increase and then decrease. We confirm this prediction in a behavioral experiment. We conclude that auditory-visual speech perception obeys the same notion of optimality previously observed only for simple multisensory stimuli.

Ross, Lars A.; Foxe, John J.; Parra, Lucas C.

2009-01-01

350

Design and operating features of the high-level waste vitrification system for the West Valley demonstration project  

SciTech Connect

A liquid-fed joule-heated ceramic melter system is the reference process for immobilization of the high-level liquid waste in the US and several foreign countries. This system has been under development for over ten years at Pacific Northwest Laboratory and other national laboratories operated for the US Department of Energy. Pacific Northwest Laboratory contributed to this research through its Nuclear Waste Treatment Program and used applicable data to design and test melters and related systems using remote handling of simulated radioactive wastes. This report describes the equipment designed in support of the high-level waste vitrification program at West Valley, New York. Pacific Northwest Laboratory worked closely with West Valley Nuclear Services Company to design a liquid-fed ceramic melter, a liquid waste preparation and feed tank and pump, an off-gas treatment scrubber, and an enclosed turntable for positioning the waste canisters. Details of these designs are presented including the rationale for the design features and the alternatives considered.

Siemens, D.H.; Beary, M.M.; Barnes, S.M.; Berger, D.N.; Brouns, R.A.; Chapman, C.C.; Jones, R.M.; Peters, R.D.; Peterson, M.E.

1986-03-01

351

Temporal bone histopathological features of a worker who received high doses of radiation in a criticality accident: a case report.  

PubMed

In 1999, three workers received high doses of radiation in a small Japanese plant while they were preparing fuel for an experimental reactor. This criticality accident at melting point was caused by the addition of too much uranium enriched to a relatively high level, causing a 'criticality' (a limited uncontrolled nuclear chain reaction), which continued intermittently for 20 h. The three workers concerned were hospitalized, two in a critical condition. The first worker died 12 weeks later, and the second worker 7 months later. The third worker is in a healthy condition. We report on the temporal bone histopathological features of the second worker. Our temporal bone study revealed: 1) the large loss of bone marrow tissue with a small number of myelocytes remaining in the mastoid bone and the abundance of fatty tissue in the mastoid bone, 2) inflammation of the mucosal layer of the middle ear and the mastoid air cells, 3) mild degeneration of the spiral ganglions and the sensory hair cells of the cochlea, 4) mild degenerative changes of sensory hair cells of the semicircular canals and otolith organs, and 5) vestibular ganglions and geniculate ganglions were well preserved. PMID:21162658

Kaga, Kimitaka; Maeshima, Arafumi; Tsuzuku, Toshihiro; Kondo, Kenji; Morizono, Tetsuo

2011-04-01

352

Mitotic Crossing over and Nondisjunction in Translocation Heterozygotes of Aspergillus  

PubMed Central

To analyze mitotic recombination in translocation heterozygotes of A. nidulans two sets of well-marked diploids were constructed, homo- or heterozygous for the reciprocal translocations T1(IL;VIIR) or T2(IL;VIIIR) and heterozygous for selective markers on IL. It was found that from all translocation heterozygotes some of the expected mitotic crossover types could be selected. Such crossovers are monosomic for one translocated segment and trisomic for the other and recovery depends on the relative viabilities of these unbalanced types. The obtained segregants show characteristically reduced growth rates and conidiation dependent on sizes and types of mono- and trisomic segments, and all spontaneously produce normal diploid sectors. Such secondary diploid types either arose in one step of compensating crossing over in the other involved arm, or—more conspicuously—in two steps of nondisjunction via a trisomic intermediate.—In both of the analyzed translocations the segments translocated to IL were extremely long, while those translocated from IL were relatively short. The break in I for T1(I;VII) was located distal to the main selective marker in IL, while that of T2(I;VIII) had been mapped proximal but closely linked to it. Therefore, as expected, the selected primary crossover from the two diploids with T2( I;VIII) in coupling or in repulsion to the selective marker, showed the same chromosomal imbalance and poor growth. These could however be distinguished visually because they spontaneously produced different trisomic intermediates in the next step, in accordance with the different arrangement of the aneuploid segments. On the other hand, from diploids heterozygous for T1( I;VII) mitotic crossovers could only be selected when the selective markers were in coupling with the translocation; these crossovers were relatively well-growing and produced frequent secondary segregants of the expected trisomic, 2n+VII, type. For both translocations it was impossible to recover the reciprocal crossover types (which would be trisomic for the distal segments of I and monosomic for most of groups VII or VIII) presumably because these were too inviable to form conidia.—In addition to the selected segregants of expected types a variety of unexpected ones were isolated. The conditions of selection used favour visual detection of aneuploid types, even if these produce only a few conidial heads and are not at a selective advantage. For T2(I;VIII) these "non-selected" unbalanced segregants were mainly "reciprocal" crossovers of the same phenotype and imbalance as the selected ones. For T1(I;VII) two quite different types were obtained, both possibly originating with loss of the small VII–I translocation chromosome. One was isolated when the selective marker in repulsion to T1(I;VII) was used and, without being homo- or hemizygous for the selective marker, it produced stable sectors homozygous for this marker. The other was obtained from both coupling and repulsion diploids and showed a near-diploid genotype; it produced practically only haploid stable sectors of the type expected from monosomics, 2n–1 for the short translocation chromosome.

Kafer, Etta

1976-01-01

353

Biological features of core networks that result from a high-fat diet in hepatic and pulmonary tissues in mammary tumour-bearing, obesity-resistant mice.  

PubMed

We previously demonstrated that the chronic consumption of a high-fat diet (HFD) promotes lung and liver metastases of 4T1 mammary carcinoma cells in obesity-resistant BALB/c mice. To examine early transcriptional responses to tumour progression in the liver and lungs of HFD-fed mice, 4-week-old female BALB/c mice were divided into four groups: sham-injected, control diet (CD)-fed; sham-injected, HFD-fed (SH); 4T1 cell-injected, CD-fed (TC); 4T1 cell-injected, HFD-fed (TH). Following 16 weeks of either a CD or HFD, 4T1 cells were injected into the mammary fat pads of mice in the TC and TH groups and all mice were continuously fed identical diets. At 14 d post-injection, RNA was isolated from hepatic and pulmonary tissues for microarray analysis of mRNA expression. Functional annotation and core network analyses were conducted for the TH/SH Unique gene set. Inflammation in hepatic tissues and cell mitosis in pulmonary tissues were the most significant biological functions in the TH/SH Unique gene set. The biological core networks of the hepatic TH/SH Unique gene set were characterised as those genes involved in the activation of acute inflammatory responses (Orm1, Lbp, Hp and Cfb), disordered lipid metabolism and deregulated cell cycle progression. Networks of the pulmonary Unique gene set displayed the deregulation of cell cycle progression (Cdc20, Cdk1 and Bub1b). These HFD-influenced alterations may have led to favourable conditions for the formation of both pro-inflammatory and pro-mitotic microenvironments in the target organs that promote immune cell infiltration and differentiation, as well as the infiltration and proliferation of metastatic tumour cells. PMID:23234678

Kim, Eun Ji; Oh, Hea Young; Heo, Hyoung-Sam; Hong, Ji Eun; Jung, Sung-Jae; Lee, Ki Won; Park, Jong Hoon; Hur, Cheol-Goo; Park, Jung Han Yoon

2013-07-28

354

Geophysical investigations of the Southeast Tyrrhenian Sea (Italy): volcanic features of the Palinuro Seamount enhanced by high resolution DTM  

NASA Astrophysics Data System (ADS)

The Palinuro Seamount is a volcanic edifice located in the southeastern Tyrrhenian Sea, the small extensional back-arc basin in the Central Mediterranean Sea. Although several geophysical studies have been performed in the Tyrrhenian Sea, the Palinuro Seamount has not yet been subjected to intensive geophysical exploration, despite its global extension, thus representing the less known Seamount of the area. Previous studies on this Seamount focused on volcanic products, magnetic profiles, single beam data and, recentely, multibeam swath batimetry describing, the latter two, the general physiographic asset of the volcanic complex. On November 2007, a geophysical survey was performed by IAMC-CNR research institute (Naples, Italy) in the southeastern Tyrrhenian Sea within the "Aeolian_2007" cruise onboard the Urania oceanographic vessel. During the second Leg of the survey, detailed multibeam data acquisition was carried out in order to obtain high resolution DTM of the major Seamounts in the study area. Here we report a new, very high resolution Digital Terrain Model (DTM) of the Palinuro Seamount, resulting by multibeam swath bathymetric data. More than 1.000 squared Km of new high resolution multibeam sonar data have been processed and interpreted from IAMC - CNR of Naples. The processed bathymetric data of the seamount cover a depth range -3200 / -84 meters and unreported topographic features were detected both below 1000 m in depth and at the summit. The DEM evidences a global extension larger than that expected, characterized by a roughly elliptical shape extending about 55 km along E-W and 25 km in the N-S direction. The morphology reveals a very articulated summit consisting in a group of overlapped and/or coalescent volcanic cones inside collapsed calderas. Relic domes of calderic collapses are identifiable both in the western and in the central sectors of the Palinuro Seamount.

Passaro, S.; Milano, G.; Sprovieri, M.; Marsella, E.; Ruggieri, S.

2009-04-01

355

Segregation of recessive phenotypes in somatic cell hybrids role of mitotic recombination, gene inactivation, and chromosome nondisjunction  

SciTech Connect

Somatic cell hybrids heterozygous at the emetine resistance locus (emt/sup r//emt/sup +/) or the chromate resistance locus (chr/sup r//chr/sup +/) are known to segregate the recessive drug resistance phenotype at high frequency. The authors have examined mechanisms of segregation in Chinese hamster cell hybrids heterozygous at these two loci, both of which map to the long arm of Chinese hamster chromosome 2. To allow the fate of chromosomal arms through the segregation process, our hybrids were also heterozygous at the mtx (methotrexate resistance) locus on the short arm of chromosome 2 and carried cytogenetically marked chromosomes with either a short-arm deletion 2p/sup -/) or a long-arm addition (2q/sup +/). Karotype and phenotype analysis of emetine- or chromate-resistant segregants from such hybrids allowed us to distinguish four potential segregation mechanisms: (i) loss of the emt/sup +/ - or chr/sup +/-bearing chromosome; (ii) mitotic recombination between the centromere and the emt or chr loci giving rise to homozygous resistant segregants; (iii) inactivation of the emt/sup +/ or chr/sup +/ alleles; and (iv) loss of the emt/sup +/ - or chr/sup +/-bearing chromosome with duplication of the homologous chromosome carrying the emt/sup r/ or chr/sup r/ allele. Of 48 independent segregants examined, only 9 (20%) arose by simple chromosome loss. Two segregants (4%) were consistent with a gene inactivation mechanism, but because of their rarity, other mechanisms such as mutation or submicroscopic deletion could not be excluded. Twenty-one segregants (44%) arose by either mitotic recombination or chromosome loss and duplication; the two mechanisms were not distinguishable in that experiment. Finally, in hybrids allowing these two mechanisms to be distinguished, 15 segregants (31%) arose by chromosome loss and duplication, and none arose by mitotic recombination.

Campbell, C.E.; Worton, R.G.

1981-04-01

356

Association of Chromosome Loss with Centromere-Adjacent Mitotic Recombination in a Yeast Disomic Haploid  

PubMed Central

Experiments designed to characterize the association between disomic chromosome loss and centromere-adjacent mitotic recombination were performed. Mitotic gene convertants were selected at two heteroallelic sites on the left arm of disomic chromosome III and tested for coincident chromosome loss. The principal results are: (1) Disomic chromosome loss is markedly enhanced (nearly 40-fold) over basal levels among mitotic gene convertants selected to arise close to the centromere; no such enhancement is observed among convertants selected to arise relatively far from the centromere. (2) Chromosome loss is primarily associated with proximal allele conversion at the centromere-adjacent site, and many of these convertants are reciprocally recombined in the adjacent proximal interval. (3) Partial aneuploid exceptions provisionally identified as carrying left arm telocentrics have been found. A testable model is proposed suggesting that centromere involvement in genetic recombination may precipitate segregational disfunction leading to mitotic chromosome loss.

Campbell, D. A.; Fogel, S.

1977-01-01

357

Identification and Characterization of Components of the Mitotic Spindle Checkpoint Pathway in Fission Yeast.  

National Technical Information Service (NTIS)

During anaphase of mitosis, sister chromatids are separated by the dynamic mitotic spindle. Failure to equally distribute the chromosomal DNA can lead to genetic loss and aneuploidy. In eukaryotic cells, the spindle assembly checkpoint monitors the attach...

S. C. Kadura S. Sazer

2001-01-01

358

Identification and Characterization of Components of the Mitotic Spindle Checkpoint Pathway in Fission Yeast.  

National Technical Information Service (NTIS)

During anaphase of mitosis, sister chromatids are separated by the mitotic spindle. The spindle assembly checkpoint protects the integrity of the genome by initiating a cell cycle delay if chromosomes are not property attached to the spindle. Cells lackin...

S. Kadura S. Sazer

2003-01-01

359

Identification and Characterization of Components of the Mitotic Spindle Checkpoint Pathway Using Fission Yeast.  

National Technical Information Service (NTIS)

During anaphase of mitosis, sister chromatids are separated by the mitotic spindle. The spindle assembly checkpoint protects the integrity of the genome by initiating a cell cycle delay if chromosomes are not properly attached to the spindle. Cells lackin...

S. Kadura S. Sazar

2002-01-01

360

Phosphorylation of the Proapoptotic BH3-Only Protein Bid Primes Mitochondria for Apoptosis during Mitotic Arrest  

PubMed Central

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

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

2014-01-01

361

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

PubMed Central

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.

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

2011-01-01

362

Inhibition of a Mitotic Motor Protein: Where, How, and Conformational Consequences  

SciTech Connect

We report here the first inhibitor-bound structure of a mitotic motor protein. The 1.9 {angstrom} resolution structure of the motor domain of KSP, bound with the small molecule monastrol and Mg{sup 2+} {center_dot} ADP, reveals that monastrol confers inhibition by 'induced-fitting' onto the protein some 12 {angstrom} away from the catalytic center of the enzyme, resulting in the creation of a previously non-existing binding pocket. The structure provides new insights into the biochemical and mechanical mechanisms of the mitotic motor domain. Inhibition of KSP provides a novel mechanism to arrest mitotic spindle formation, a target of several approved and investigative anti-cancer agents. The structural information gleaned from this novel pocket offers a new angle for the design of anti-mitotic agents.

Yan, Youwei; Sardana, Vinod; Xu, Bei; Homnick, Carl; Halczenko, Wasyl; Buser, Carolyn A.; Schaber, Michael; Hartman, George D.; Huber, Hans E.; Kuo, Lawrence C. (Merck)

2010-11-16

363

Phosphorylation of Lte1 by Cdk prevents polarized growth during mitotic arrest in S. cerevisiae  

PubMed Central

Lte1 is known as a regulator of mitotic progression in budding yeast. Here we demonstrate phosphorylation-dependent inhibition of polarized bud growth during G2/M by Lte1. Cla4 activity first localizes Lte1 to the polarity cap and thus specifically to the bud. This localization is a prerequisite for subsequent Clb–Cdk-dependent phosphorylation of Lte1 and its relocalization to the entire bud cortex. There, Lte1 interferes with activation of the small GTPases, Ras and Bud1. The inhibition of Bud1 prevents untimely polarization until mitosis is completed and Cdc14 phosphatase is released. Inhibition of Bud1 and Ras depends on Lte1’s GEF-like domain, which unexpectedly inhibits these small G proteins. Thus, Lte1 has dual functions for regulation of mitotic progression: it both induces mitotic exit and prevents polarized growth during mitotic arrest, thereby coupling cell cycle progression and morphological development.

Spanos, Adonis; Jensen, Sanne; Sedgwick, Steven G.

2010-01-01

364

High resolution PFPE-based molding High resolution PFPE-based molding High resolution PFPE-based molding techniques for nanofabrication of high pattern density sub-20 nm features: A fundamental materials approach  

SciTech Connect

ABSTRACT. Described herein is the development and investigation of PFPE-based elastomers for high resolution replica molding applications. The modulus of the elastomeric materials was increased through synthetic and additive approaches while maintaining relatively low surface energies (<25 mN/m). Using practically relevant large area master templates, we show that the resolution of the molds is strongly dependant upon the elastomeric mold modulus. A composite mold approach was used to form flexible molds out of stiff, high modulus materials that allow for replication of sub-20 nm post structures. Sub-100 nm line grating master templates, formed using e-beam lithography, were used to determine the experimental stability of the molding materials. It was observed that as the feature spacing decreased, high modulus composite molds were able to effectively replicate the nano-grating structures without cracking or tear-out defects that typically occur with high modulus elastomers.

Williams, Stuart S [University of North Carolina, Chapel Hill; Samulski, Edward [University of North Carolina, Chapel Hill; Lopez, Renee [University of North Carolina, Chapel Hill; Ruiz, Ricardo [Hitachi; DeSimone, Joseph [University of North Carolina, Chapel Hill; Retterer, Scott T [ORNL

2010-01-01

365

From The Cover: Evaluating putative mechanisms of the mitotic spindle checkpoint  

Microsoft Academic Search

The mitotic spindle checkpoint halts the cell cycle until all chromosomes are attached to the mitotic spindles. Evidence suggests that the checkpoint prevents cell-cycle progression by inhibiting the activity of the APC-Cdc20 complex, but the precise mechanism underlying this inhibition is not yet known. Here, we use mathematical modeling to compare several mechanisms that could account for this inhibition. We

Andreas Doncic; Eshel Ben-Jacob; Naama Barkai

2005-01-01

366

CtBPs promote mitotic fidelity through their activities in the cell nucleus  

Microsoft Academic Search

CtBPs form NADH-sensitive chromatin-modifying complexes, which link cellular metabolism to gene transcription. They also function in the cytoplasm to regulate Golgi fissioning; their inhibition can consequently cause a Golgi-dependent checkpoint in G2. We have recently identified a novel role of CtBPs in the maintenance of mitotic fidelity; inhibition of CtBP synthesis resulting in reduced association of aurora B with mitotic

C N Birts; L M Bergman; J P Blaydes

2011-01-01

367

In vitro root induction in weedy amaranthus species to obtain mitotic chromosomes  

Microsoft Academic Search

Summary  Mitotic chromosome analysis has proven to be an important tool in monitoring the potential for genetic exchange among related\\u000a plant species. One major obstacle to using mitotic chromosome analysis in any species is obtaining large numbers of clear,\\u000a well-spread metaphase chromosomes necessary to perform cytological techniques such as chromosome banding and fluorescent in situ hybridization. The ability to obtain good

Tatiana C. Tatum; Robert Skirvin; Patrick J. Tranel; Margaret Norton

2005-01-01

368

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

PubMed Central

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

Walsh, Charles J.

2012-01-01

369

Differential Requirements for DNA Replication in the Activation of Mitotic Checkpoints in Saccharomyces cerevisiae  

Microsoft Academic Search

Checkpoints prevent inaccurate chromosome segregation by inhibiting cell division when errors in mitotic processes are encountered. We used a temperature-sensitive mutation, dbf4, to examine the requirement for DNA replication in establishing mitotic checkpoint arrest. We used g-irradiation to induce DNA damage and hydroxyurea to limit deoxyribonucleotides in cells deprived of DBF4 function to investigate the requirement for DNA replication in

PENNY A. TAVORMINA; YANCHANG WANG; DANIEL J. BURKE

1997-01-01

370

Deficiency in SNM1 Abolishes an Early Mitotic Checkpoint Induced by Spindle Stress  

Microsoft Academic Search

Spindle poisons represent an important class of anticancer drugs that act by interfering with microtubule polymerization and dynamics and thereby induce mitotic checkpoints and apoptosis. Here we show that mammalian SNM1 functions in an early mitotic stress checkpoint that is distinct from the well-characterized spindle checkpoint that regulates the metaphase-to-anaphase transition. Specifically, we found that compared to wild-type cells, Snm1-deficient

Shamima Akhter; Christopher T. Richie; J. M. Deng; E. Brey; X. Zhang; C. Patrick; Richard R. Behringer; Randy J. Legerski

2004-01-01

371

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

Microsoft Academic Search

Recently, it has been suggested that mitotic recombination is involved in tumor promotion. On this basis, one might expect tumor promoters to be recombinagenic. D7 is a diploid strain of yeast in which both mutation and mitotic recombination can be measured. We have used this strain to assay the known tumor promoters, iodacetate, anthralin, and 12-0-tetradecanoylphorbol-13-acetate, and the cocarcinogen, catechol,

Bernard A. Kunz; Mohammed A. Hannan; R. H. Haynes

1980-01-01

372

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

Microsoft Academic Search

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

Kathryn M. Freeman; George R. Hoffmann

2007-01-01

373

The Prp19 Complex Directly Functions in Mitotic Spindle Assembly  

PubMed Central

The conserved Prp19 (pre-RNA processing 19) complex is required for pre-mRNA splicing in eukaryotic nuclei. Recent RNAi screens indicated that knockdown of Prp19 complex subunits strongly delays cell proliferation. Here we show that knockdown of the smallest subunit, BCAS2/Spf27, destabilizes the entire complex and leads to specific mitotic defects in human cells. These could result from splicing failures in interphase or reflect a direct function of the complex in open mitosis. Using Xenopus extracts, in which cell cycle progression and spindle formation can be reconstituted in vitro, we tested Prp19 complex functions during a complete cell cycle and directly in open mitosis. Strikingly, immunodepletion of the complex either before or after interphase significantly reduces the number of intact spindles, and increases the percentage of spindles with lower microtubule density and impaired metaphase alignment of chromosomes. Our data identify the Prp19 complex as the first spliceosome subcomplex that directly contributes to mitosis in vertebrates independently of its function in interphase.

Hofmann, Jennifer C.; Tegha-Dunghu, Justus; Drager, Stefanie; Will, Cindy L.; Luhrmann, Reinhard; Gruss, Oliver J.

2013-01-01

374

Poleward microtubule flux mitotic spindles assembled in vitro  

PubMed Central

In the preceding paper we described pathways of mitotic spindle assembly in cell-free extracts prepared from eggs of Xenopus laevis. Here we demonstrate the poleward flux of microtubules in spindles assembled in vitro, using a photoactivatable fluorescein covalently coupled to tubulin and multi-channel fluorescence videomicroscopy. After local photoactivation of fluorescence by UV microbeam, we observed poleward movement of fluorescein-marked microtubules at a rate of 3 microns/min, similar to rates of chromosome movement and spindle elongation during prometaphase and anaphase. This movement could be blocked by the addition of millimolar AMP-PNP but was not affected by concentrations of vanadate up to 150 microM, suggesting that poleward flux may be driven by a microtubule motor similar to kinesin. In contrast to previous results obtained in vivo (Mitchison, T. J. 1989. J. Cell Biol. 109:637-652), poleward flux in vitro appears to occur independently of kinetochores or kinetochore microtubules, and therefore may be a general property of relatively stable microtubules within the spindle. We find that microtubules moving towards poles are dynamic structures, and we have estimated the average half-life of fluxing microtubules in vitro to be between approximately 75 and 100 s. We discuss these results with regard to the function of poleward flux in spindle movements in anaphase and prometaphase.

1991-01-01

375

The Prp19 complex directly functions in mitotic spindle assembly.  

PubMed

The conserved Prp19 (pre-RNA processing 19) complex is required for pre-mRNA splicing in eukaryotic nuclei. Recent RNAi screens indicated that knockdown of Prp19 complex subunits strongly delays cell proliferation. Here we show that knockdown of the smallest subunit, BCAS2/Spf27, destabilizes the entire complex and leads to specific mitotic defects in human cells. These could result from splicing failures in interphase or reflect a direct function of the complex in open mitosis. Using Xenopus extracts, in which cell cycle progression and spindle formation can be reconstituted in vitro, we tested Prp19 complex functions during a complete cell cycle and directly in open mitosis. Strikingly, immunodepletion of the complex either before or after interphase significantly reduces the number of intact spindles, and increases the percentage of spindles with lower microtubule density and impaired metaphase alignment of chromosomes. Our data identify the Prp19 complex as the first spliceosome subcomplex that directly contributes to mitosis in vertebrates independently of its function in interphase. PMID:24069358

Hofmann, Jennifer C; Tegha-Dunghu, Justus; Dräger, Stefanie; Will, Cindy L; Lührmann, Reinhard; Gruss, Oliver J

2013-01-01

376

A dynamic, mitotic-like mechanism for bacterial chromosome segregation.  

PubMed

The mechanisms that mediate chromosome segregation in bacteria are poorly understood. Despite evidence of dynamic movement of chromosome regions, to date, mitotic-like mechanisms that act on the bacterial chromosome have not been demonstrated. Here we provide evidence that the Vibrio cholerae ParAI and ParBI proteins are components of an apparatus that pulls the origin region of the large V. cholerae chromosome to the cell pole and anchors it there. ParBI interacts with a conserved origin-proximal, centromere-like site (parSI) that, following chromosome replication, segregates asymmetrically from one pole to the other. While segregating, parSI stretches far away from neighboring chromosomal loci. ParAI forms a dynamic band that extends from the pole to the segregating ParBI/parSI complex. Movement of ParBI/parSI across the cell occurs in concert with ParAI retraction. Deletion of parAI disrupts proper origin localization and segregation dynamics, and parSI no longer separates from nearby regions. These data suggest that ParAI forms a dynamic structure that pulls the ParBI-bound chromosome to the pole in a process analogous to anaphase of eukaryotic mitosis. PMID:17158745

Fogel, Michael A; Waldor, Matthew K

2006-12-01

377

EAM-based high-speed 100-km OFDM transmission featuring tolerant modulator operation enabled using SSII cancellation.  

PubMed

In this study, a technique was developed to compensate for nonlinear distortion through cancelling subcarrier-to-subcarrier intermixing interference (SSII) in an electroabsorption modulator (EAM)-based orthogonal frequency-division multiplexing (OFDM) transmission system. The nonlinear distortion to be compensated for is induced by both EAM nonlinearity and fiber dispersion. Because an OFDM signal features an inherently high peak-to-average power ratio, a trade-off exists between the optical modulation index (OMI) and modulator nonlinearity. Therefore, the nonlinear distortion limits the operational tolerance of the bias voltage and the driving power to a small region. After applying the proposed SSII cancellation, the OMI of an OFDM signal was increased yielding only a small increment of nonlinear distortion, and the tolerance region of the operational conditions was also increased. By employing the proposed scheme, this study successfully demonstrates 50-Gbps OFDM transmission over 100-km dispersion-uncompensated single-mode fiber based on a single 10-GHz EAM. PMID:24977559

Chen, Hsing-Yu; Wei, Chia-Chien; Lu, I-Cheng; Chen, Yu-Chao; Chu, Hsuan-Hao; Chen, Jyehong

2014-06-16

378

Feature Indeterminacy and Feature Resolution.  

ERIC Educational Resources Information Center

Presents a theory of feature representation that accounts for feature indeterminacy and feature resolution within the lexical functional grammar (LFG) framework. The representations discussed, together with minimal extensions of LFG's description language, enable a simple and intuitive characterization of both these phenomena. (Author/VWL)

Dalrymple, Mary; Kaplan, Ronald M.

2000-01-01

379

Cellular analyses of the mitotic region in the Caenorhabditis elegans adult germ line.  

PubMed

The Caenorhabditis elegans germ line provides a model for understanding how signaling from a stem cell niche promotes continued mitotic divisions at the expense of differentiation. Here we report cellular analyses designed to identify germline stem cells within the germline mitotic region of adult hermaphrodites. Our results support several conclusions. First, all germ cells within the mitotic region are actively cycling, as visualized by bromodeoxyuridine (BrdU) labeling. No quiescent cells were found. Second, germ cells in the mitotic region lose BrdU label uniformly, either by movement of labeled cells into the meiotic region or by dilution, probably due to replication. No label-retaining cells were found in the mitotic region. Third, the distal tip cell niche extends processes that nearly encircle adjacent germ cells, a phenomenon that is likely to anchor the distal-most germ cells within the niche. Fourth, germline mitoses are not oriented reproducibly, even within the immediate confines of the niche. We propose that germ cells in the distal-most rows of the mitotic region serve as stem cells and more proximal germ cells embark on the path to differentiation. We also propose that C. elegans adult germline stem cells are maintained by proximity to the niche rather than by programmed asymmetric divisions. PMID:16672375

Crittenden, Sarah L; Leonhard, Kimberly A; Byrd, Dana T; Kimble, Judith

2006-07-01

380

Dual function microtubule- and mitochondria-associated proteins mediate mitotic cell death  

PubMed Central

Background Survival and evolution of aneuploid cells after an asymmetric segregation of chromosomes at mitosis may be the common initiating event and underlying cause of the genetic diversity and adaptability of cancers. We hypothesize that mechanisms exist to detect impending aneuploidy and prevent it before completion of an aberrant mitosis. Methods The distribution of isoforms of C19ORF5, an interactive partner with mitochondria-associated LRPPRC and tumor suppressor RASSF1A, state of spindle microtubules and mitochondrial aggregation was analyzed in synchronized mitotic cells and cells stalled in mitosis after treatment with paclitaxel. Results C19ORF5 distributed broadly across the mitotic spindle and reversibly accumulated during reversible mitotic arrest. Prolonged stabilization of microtubules caused an accumulation of a C19ORF5 product with dual MAP and MtAP properties that caused irreversible aggregation of mitochondria and death of mitotic cells. Conclusion Dual function microtubule-associated (MAP) and mitochondria-associated (MtAP) proteins generated by prolonged mitotic arrest trigger mitochondrial-induced mitotic cell death. This is a potential mechanism to prevent minimal survivable aneuploidy resulting from an aberrant cell division and cancers in general at their earliest common origin.

Liu, Leyuan; Xie, Rui; Yang, Chaofeng; McKeehan, Wallace L.

2011-01-01

381

The Mitotic Checkpoint Gene, SIL is Regulated by E2F1  

PubMed Central

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

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

2009-01-01

382

An unusual DNA binding compound, S23906, induces mitotic catastrophe in cultured human cells.  

PubMed

The biochemical pathways that lead cells to mitotic catastrophe are not well understood. To identify these pathways, we have taken an approach of treating cells with a novel genotoxic compound and characterizing whether cells enter mitotic catastrophe or not. S23906 is a novel acronycine derivative that forms adducts with the N2 residue of guanine in the minor groove of the DNA helix and destabilizes base pairing to cause helix opening. We observed, in HeLa and HT-29 cells, that S23906 induced gamma-H2AX and activated checkpoint kinase 1, as did bleomycin, camptothecin, and cisplatin, when tested under equi-toxic conditions. S23906 also induced cyclin E1 protein, although this activity was not required for cytotoxicity because knock down of cyclin E1 by RNA interference did not affect the number of dead cells after treatment. Cyclin B1 levels first decreased and then increased after treatment with S23906. Cyclin B1 was associated with Cdk1 kinase activity, which correlated with an increase in the number of mitotic cells. By 32 h after treatment, at least 20% of the cells entered mitotic catastrophe as determined by microscopy. Suppression of the DNA checkpoint response by co-treatment with caffeine increased the number of cells in mitosis. These results suggest that mitotic catastrophe is one of the cellular responses to S23906 and that mitotic catastrophe may be a common cellular response to many different types of DNA damage. PMID:19758748

Cahuzac, Nathalie; Studény, Aurélie; Marshall, Kris; Versteege, Isabella; Wetenhall, Kate; Pfeiffer, Bruno; Léonce, Stéphane; Hickman, John A; Pierré, Alain; Golsteyn, Roy M

2010-03-28

383

Serum high mobility group box-1 (HMGB1) is closely associated with the clinical and pathologic features of gastric cancer  

PubMed Central

Background High mobility group box-1 (HMGB1) is a newly recognized factor regulating cancer cell tumorigenesis, expansion and invasion. We investigated the correlation between the serum HMGB1 levels and the clinical and pathologic features of gastric cancer and evaluated the validity of HMGB1 as a potential biomarker for the early diagnosis of gastric cancer. Methods A total of 227 subjects were classified into 5 disease groups according to the 'gastritis-dysplasia-carcinoma' sequence of gastric carcinogenesis and their serum levels of HMGB1 were analyzed by an enzyme-linked immunosorbent assay (ELISA) method. Clinical parameters, International Union Against Cancer (UICC) TNM stage, cancer size, differentiation or lymphatic invasion, vascular or perineural invasion and prognosis were used as analysis variables. Results The serum HMGB1 levels were significantly different among disease groups (ANOVA, p < 0.05) and HMGB1 levels tended to increase according to the progression of gastric carcinogenesis. Serum HMGB1 levels were significantly associated with depth of invasion, lymph node metastasis, tumor size, and poor prognosis (p < 0.05). However, HMGB1 levels were not associated with patient gender or age, differentiation of tumor cells, or lymphatic, vascular and perineural invasion, or the existence of distant metastasis in advanced cancer (p > 0.05). The sensitivity and specificity of serum HMGB1 was 71% and 67% (cut-off value of 5 ng/ml) for the diagnosis of early gastric cancer, and 70% and 64% (cut-off value of 4 ng/ml) for the diagnosis of high-risk lesions, respectively. These values were greater than those for carcinoembryonic antigen (CEA) (30–40% of sensitivity). Conclusion HMGB1 appears to be a useful serological biomarker for early diagnosis as well as evaluating the tumorigenesis, stage, and prognosis of gastric cancer.

Chung, Hye Won; Lee, Sang-Guk; Kim, Heejung; Hong, Duck Jin; Chung, Jae Bock; Stroncek, David; Lim, Jong-Baeck

2009-01-01

384

Mapping epibenthic assemblages and their relations to sedimentary features in shallow-water, high-energy environments  

NASA Astrophysics Data System (ADS)

Knowledge of spatial relationships among benthic biota and sedimentary features in shallow-water (<30 m) high-energy environments has been severely limited by sampling technology. We describe and report tests of a SCUBA-diving mapping method specifically for this region. Underwater acoustic location is used to achieve meter-scale resolution over kilometer-scale regions of the sea floor. A triad of acoustic transponders is bottom-mounted at known positions, 300-500 m apart. Transported by underwater personal vehicles, SCUBA-divers map the bed using hand-held acoustic receivers that record ranges to the transponders. The mean error of acoustic fixes was 2.4±1.2 m in a 0.5 km×1.0 km test area. Dense assemblages of epibenthic animals were mapped relative to sediment texture and bedforms off the exposed south coast of Martha's Vineyard Island, Massachusetts, USA. Surveys one month apart within a 0.6 km×0.6 km area (8-12 m depth) revealed 100-m-scale patches of the tube worm Spiophanes bombyx (?30,000 m -2) in fine sand and of the sand dollar Echinarachnius parma (?55 m -2) in coarse sand. Raised mud patches that, together with fine sand, occurred in two shore-perpendicular belts are likely exposed, ancient marsh deposits. Depth gradients of sand-ripple geometry indicated that ripples in deeper areas were not in equilibrium with wave conditions monitored during surveys; i.e., they were relict ripples. Thus, sand dollars in some areas may have had >1 month to rework surficial sands since their transformation by physical processes. Linear regressions of ripple characteristics against sand dollar or tube worm densities were not significant, although such relationships would be highly dependent on temporal scale. The survey method described here can be used at more frequent intervals to explore such interactions between epibenthic animals and sediment-transport dynamics.

Sisson, John D.; Shimeta, Jeff; Zimmer, Cheryl Ann; Traykovski, Peter

2002-03-01

385

Low specific nitrate uptake rate: A common feature of high-nutrient, low-chlorophyll marine ecosystems  

SciTech Connect

The authors have searched for common features of three high-nutrient, low-chlorophyll (HNLC) regions of interest - the Southern Ocean, the eastern equatorial Pacific, and Station P in the northeast Pacific. In each of these areas, the rates of specific NO{sub 3} uptake, whether normalized to particulate organic nitrogen (PON) or chlorophyll, are low compared to coastal upwelling systems with comparable nutrient concentrations. When maximum values of NO{sub 3} concentration and maximum values of PON-specific {sup 15}NO{sub 3} uptake, V{sup 15}NO{sub 3} track for the coastal systems, and a low V{sup 15}NO{sub 3} track for the three HNLC regions which have V{sup 15}NO{sub 3} values consistent with oligotrophic regions and so are functionally oligotrophic. These values of V{sup 15}NO{sub 3} are too low to allow biomass accumulation and the formation of blooms of diatoms. One possible reason for the lack of high V{sup 15}NO{sub 3} values in the HNLC regions is that seeding of the large, fast-growing, fast-sinking diatoms is inadequate and primarily due to the lack of a bottom or other recirculation system to assure a supply of these diatoms to the surface regions. Grazing control limits biomass development and may function to hold V{sup 15}NO{sub 3} to low values resulting in conditions certain to appear as HNLC. Comparison with model results suggests that deep mixed layers in the Southern Ocean and at Station P may limit V{sup 15}NO{sub 3} and that in much of the eastern equatorial Pacific NO{sub 3} concentrations are too low for VNO{sub 3} to develop to coastal upwelling values.

Dugdale, R.C.; Wilkerson, F.P. (Univ. of Southern California, Los Angeles (United States))

1991-12-01

386

Morphological Features of Cell Blocks Prepared from Residual Liqui-PREP Samples Can Distinguish between High-Grade Squamous Intraepithelial Lesions and Squamous Cell Carcinomas  

Microsoft Academic Search

Objective: To evaluate the diagnostic value and compare morphological features of cell block sections of high-grade squamous intraepithelial lesions (HSIL) and squamous cell carcinomas (SCC). Study Design: A total of 135 cell blocks were prepared from residual Liqui-PREP samples. Of these, 43 biopsy-confirmed cases (24 HSIL and 19 SCC) were reviewed. Morphological features determined included cell clusters, epithelial-stromal interface, stromal

Qingzhu Wei; Jianghuan Liu; Zhixiong Zhang; Qiao Yang; Tong Zhao

2011-01-01

387

Coordinated Observations of Aeolian Features from the Mars Exploration Rovers (MER) and the Mars Express High Resolution Stereo Camera and Other Orbiters  

NASA Technical Reports Server (NTRS)

Surface features associated with aeolian (wind) processes at the Mars Exploration Rover (MER) landing sites for Spirit (Gusev crater) and Opportunity (Sinus Meridiani) were observed from the surface and from orbit through coordinated observations by the rovers and the Mars Express orbiter High Resolution Stereo Camera and compared with features seen in other orbiter data and with wind vectors predicted by a numerical mesoscale model of the atmosphere.

Greeley, R.; Thompson, S. D.; Whelley, P. L.; Squyres, S.; Neukum, G.; Arvidson, R.; Malin, M.; Kuzmin, R.; Christensen, P.; Rafkin, S.

2004-01-01

388

Anthropometric features and body composition of young athletes practicing karate at a high and medium competitive level.  

PubMed

The aim of the study was to examine the anthropometric features and body composition of athletes practising karate at a high and medium competitive level. Our study was carried out on a sample of 35 subjects practising karate and aged from 16.0 to 32.5 years. This sample was divided into two groups: group 1 ( n=14 elite athletes) and group 2 ( n=21 amateur athletes). Various anthropometric measurements were taken (weight, height both standing and sitting, diameters, circumferences and skinfold thickness) from which different anthropometric indices were calculated (body mass index, Scelic and Grant indices, arm muscle circumference and area), and the somatotype was then determined. The body composition of each subject was assessed using the skinfold technique and the Jackson-Pollock (J-P) and Sloan-Weir (S-W) equations. The two groups of athletes showed very similar measurements regarding anthropometric characteristics. Only the Scelix index presented a significantly different value in the two groups (49.6+/-1.3 for group 1 vs. 51.1+/-1.3 for group 2; p<0.01). Group 1 showed a mesomorphic-ectomorphic somatotype, while the amateur athletes presented a balanced mesomorphic type. Moreover, a lower percentage of fat mass was more frequent in the first group (J-P=8.1+/-2.4%; S-W=8.9+/-3.3%) than in the second one (J-P=9.8+/-1.6%; S-W=11.2+/-3.7%), although the differences between the two groups were not significant. We conclude that group 1 is characterized by a slightly prominent vertical development of the skeletal frame. This could be an anthropometric characteristic that is best suited to meet the specific functional requirements of this sport. Moreover, both groups of athletes are characterized by a low percentage of fat mass, particularly the elite group. PMID:14618456

Giampietro, M; Pujia, A; Bertini, I

2003-10-01

389

MYCN-mediated overexpression of mitotic spindle regulatory genes and loss of p53-p21 function jointly support the survival of tetraploid neuroblastoma cells.  

PubMed

High-risk neuroblastomas often harbor structural chromosomal alterations, including amplified MYCN, and usually have a near-di/tetraploid DNA index, but the mechanisms creating tetraploidy remain unclear. Gene-expression analyses revealed that certain MYCN/MYC and p53/pRB-E2F target genes, especially regulating mitotic processes, are strongly expressed in near-di/tetraploid neuroblastomas. Using a functional RNAi screening approach and live-cell imaging, we identified a group of genes, including MAD2L1, which after knockdown induced mitotic-linked cell death in MYCN-amplified and TP53-mutated neuroblastoma cells. We found that MYCN/MYC-mediated overactivation of the metaphase-anaphase checkpoint synergizes with loss of p53-p21 function to prevent arrest or apoptosis of tetraploid neuroblastoma cells. PMID:23186832

Gogolin, Sina; Batra, Richa; Harder, Nathalie; Ehemann, Volker; Paffhausen, Tobias; Diessl, Nicolle; Sagulenko, Vitaliya; Benner, Axel; Gade, Stephan; Nolte, Ingo; Rohr, Karl; König, Rainer; Westermann, Frank

2013-04-30