WorldWideScience

Sample records for governing cell division

  1. UKAEA Government Division Annual Review 1994-95

    International Nuclear Information System (INIS)

    1995-01-01

    This is the first annual review of the United Kingdom Atomic Energy Authority (UKAEA) Government Division. The Division was set up in April 1994 with the primary responsibility of completing the UKAEA's nuclear mission by caring for and decommissioning the radioactive facilities used in pursuit of the national nuclear programme over the past 50 years; this includes the safe disposal of the resulting radioactive waste. The progress made in the first year towards carrying out this responsibility at the lowest cost while continuing to ensure safety and protection of the environment is reported. Other responsibilities of Government Division which are reviewed include: management of the UKAEA's sites, buildings and operating facilities; oversight of the United Kingdom fusion research programme and provision for the Joint European Torus which is situated next to the Culham fusion site; and the UKAEA Constabulary. Appended to the review are a financial statement and a list of the main decommissioning tasks. (UK)

  2. Cell Division Synchronization

    Science.gov (United States)

    The report summarizes the progress in the design and construction of automatic equipment for synchronizing cell division in culture by periodic...Concurrent experiments in hypothermic synchronization of algal cell division are reported.

  3. Novel Coiled-Coil Cell Division Factor ZapB Stimulates Z Ring Assembly and Cell Division

    DEFF Research Database (Denmark)

    Ebersbach, Gitte; Galli, Elizabeth; Møller-Jensen, Jakob

    2008-01-01

    Formation of the Z ring is the first known event in bacterial cell division. However, it is not yet known how the assembly and contraction of the Z ring is regulated. Here, we identify a novel cell division factor ZapB in Escherichia coli that simultaneously stimulates Z ring assembly and cell...... division. Deletion of zapB resulted in delayed cell division and the formation of ectopic Z rings and spirals whereas overexpression of ZapB resulted in nucleoid condensation and aberrant cell divisions. Localization of ZapB to the divisome depended on FtsZ but not FtsA, ZipA or FtsI and ZapB interacted...... with FtsZ in a bacterial two-hybrid analysis. The simultaneous inactivation of FtsA and ZipA prevented Z ring assembly and ZapB localization. Time lapse microscopy showed that ZapB-GFP is present at mid-cell in a pattern very similar to that of FtsZ. Cells carrying a zapB deletion and the ftsZ84ts allele...

  4. A novel cell division factor from tobacco 2B-13 cells that induced cell division in auxin-starved tobacco BY-2 cells

    Science.gov (United States)

    Shimizu, Takashi; Eguchi, Kentaro; Nishida, Ikuo; Laukens, Kris; Witters, Erwin; van Onckelen, Harry; Nagata, Toshiyuki

    2006-06-01

    Effects of auxin as plant hormones are widespread; in fact in almost all aspects of plant growth and development auxin plays a pivotal role. Although auxin is required for propagating cell division in plant cells, its effect upon cell division is least understood. If auxin is depleted from the culture medium, cultured cells cease to divide. It has been demonstrated in this context that the addition of auxin to auxin-starved nondividing tobacco BY-2 cells induced semisynchronous cell division. On the other hand, there are some cell lines, named habituated cells, that can grow without auxin. The cause and reason for the habituated cells have not been clarified. A habituated cell line named 2B-13 is derived from the tobacco BY-2 cell line, which has been most intensively studied among plant cell lines. When we tried to find the difference between two cell lines of BY-2 and 2B-13 cells, we found that the addition of culture filtrated from the auxin-habituated 2B-13 cells induced semisynchronous cell division in auxin-starved BY-2 cells. The cell division factor (CDF) that is responsible for inducing cell division in auxin-starved BY-2 cells was purified to near-homogeneity by sequential passage through a hydroxyapatite column, a ConA Sepharose column and a Sephadex gel filtration column. The resulting purified fraction appeared as a single band of high molecular weight on sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels by silver staining and was able to induce cell division in auxin-starved BY-2 cells. Identification of the protein by MALD-TOF-MS/MS revealed that it is structurally related to P-glycoprotein from Gossypioides kirkii, which belongs to ATP-binding cassette (ABC)-transporters. The significance of CDF as a possible ABC-transporter is discussed in relationship to auxin-autotrophic growth and auxin-signaling pathway.

  5. Single-cell analysis of growth and cell division of the anaerobe Desulfovibrio vulgaris Hildenborough

    Directory of Open Access Journals (Sweden)

    Anouchka eFievet

    2015-12-01

    Full Text Available Recent years have seen significant progress in understanding basic bacterial cell cycle properties such as cell growth and cell division. While characterization and regulation of bacterial cell cycle is quite well documented in the case of fast growing aerobic model organisms, no data has been so far reported for anaerobic bacteria. This lack of information in anaerobic microorganisms can mainly be explained by the absence of molecular and cellular tools such as single cell microscopy and fluorescent probes usable for anaerobes and essential to study cellular events and/or subcellular localization of the actors involved in cell cycle.In this study, single-cell microscopy has been adapted to study for the first time, in real time, the cell cycle of a bacterial anaerobe, Desulfovibrio vulgaris Hildenborough (DvH. This single-cell analysis provides mechanistic insights into the cell division cycle of DvH, which seems to be governed by the recently discussed so-called incremental model that generates remarkably homogeneous cell sizes. Furthermore, cell division was reversibly blocked during oxygen exposure. This may constitute a strategy for anaerobic cells to cope with transient exposure to oxygen that they may encounter in their natural environment, thereby contributing to their aerotolerance. This study lays the foundation for the first molecular, single-cell assay that will address factors that cannot otherwise be resolved in bulk assays and that will allow visualization of a wide range of molecular mechanisms within living anaerobic cells.

  6. Polarity, cell division, and out-of-equilibrium dynamics control the growth of epithelial structures

    Science.gov (United States)

    Cerruti, Benedetta; Puliafito, Alberto; Shewan, Annette M.; Yu, Wei; Combes, Alexander N.; Little, Melissa H.; Chianale, Federica; Primo, Luca; Serini, Guido; Mostov, Keith E.; Celani, Antonio

    2013-01-01

    The growth of a well-formed epithelial structure is governed by mechanical constraints, cellular apico-basal polarity, and spatially controlled cell division. Here we compared the predictions of a mathematical model of epithelial growth with the morphological analysis of 3D epithelial structures. In both in vitro cyst models and in developing epithelial structures in vivo, epithelial growth could take place close to or far from mechanical equilibrium, and was determined by the hierarchy of time-scales of cell division, cell–cell rearrangements, and lumen dynamics. Equilibrium properties could be inferred by the analysis of cell–cell contact topologies, and the nonequilibrium phenotype was altered by inhibiting ROCK activity. The occurrence of an aberrant multilumen phenotype was linked to fast nonequilibrium growth, even when geometric control of cell division was correctly enforced. We predicted and verified experimentally that slowing down cell division partially rescued a multilumen phenotype induced by altered polarity. These results improve our understanding of the development of epithelial organs and, ultimately, of carcinogenesis. PMID:24145168

  7. Prokaryotic cell division: flexible and diverse

    NARCIS (Netherlands)

    den Blaauwen, T.

    2013-01-01

    Gram-negative rod-shaped bacteria have different approaches to position the cell division initiating Z-ring at the correct moment in their cell division cycle. The subsequent maturation into a functional division machine occurs in vastly different species in two steps with appreciable time in

  8. Developmental control of cell division

    NARCIS (Netherlands)

    Boxem, M. (Mike)

    2002-01-01

    During development of multicellular organisms, cell divisions need to be coordinated with the developmental program of the entire organism. Although the mechanisms that drive cells through the division cycle are well understood, very little is known about the pathways that link extracellular signals

  9. The stem cell division theory of cancer.

    Science.gov (United States)

    López-Lázaro, Miguel

    2018-03-01

    All cancer registries constantly show striking differences in cancer incidence by age and among tissues. For example, lung cancer is diagnosed hundreds of times more often at age 70 than at age 20, and lung cancer in nonsmokers occurs thousands of times more frequently than heart cancer in smokers. An analysis of these differences using basic concepts in cell biology indicates that cancer is the end-result of the accumulation of cell divisions in stem cells. In other words, the main determinant of carcinogenesis is the number of cell divisions that the DNA of a stem cell has accumulated in any type of cell from the zygote. Cell division, process by which a cell copies and separates its cellular components to finally split into two cells, is necessary to produce the large number of cells required for living. However, cell division can lead to a variety of cancer-promoting errors, such as mutations and epigenetic mistakes occurring during DNA replication, chromosome aberrations arising during mitosis, errors in the distribution of cell-fate determinants between the daughter cells, and failures to restore physical interactions with other tissue components. Some of these errors are spontaneous, others are promoted by endogenous DNA damage occurring during quiescence, and others are influenced by pathological and environmental factors. The cell divisions required for carcinogenesis are primarily caused by multiple local and systemic physiological signals rather than by errors in the DNA of the cells. As carcinogenesis progresses, the accumulation of DNA errors promotes cell division and eventually triggers cell division under permissive extracellular environments. The accumulation of cell divisions in stem cells drives not only the accumulation of the DNA alterations required for carcinogenesis, but also the formation and growth of the abnormal cell populations that characterize the disease. This model of carcinogenesis provides a new framework for understanding the

  10. Stationary Size Distributions of Growing Cells with Binary and Multiple Cell Division

    Science.gov (United States)

    Rading, M. M.; Engel, T. A.; Lipowsky, R.; Valleriani, A.

    2011-10-01

    Populations of unicellular organisms that grow under constant environmental conditions are considered theoretically. The size distribution of these cells is calculated analytically, both for the usual process of binary division, in which one mother cell produces always two daughter cells, and for the more complex process of multiple division, in which one mother cell can produce 2 n daughter cells with n=1,2,3,… . The latter mode of division is inspired by the unicellular algae Chlamydomonas reinhardtii. The uniform response of the whole population to different environmental conditions is encoded in the individual rates of growth and division of the cells. The analytical treatment of the problem is based on size-dependent rules for cell growth and stochastic transition processes for cell division. The comparison between binary and multiple division shows that these different division processes lead to qualitatively different results for the size distribution and the population growth rates.

  11. Direct interaction of FtsZ and MreB is required for septum synthesis and cell division in Escherichia coli.

    Science.gov (United States)

    Fenton, Andrew K; Gerdes, Kenn

    2013-07-03

    How bacteria coordinate cell growth with division is not well understood. Bacterial cell elongation is controlled by actin-MreB while cell division is governed by tubulin-FtsZ. A ring-like structure containing FtsZ (the Z ring) at mid-cell attracts other cell division proteins to form the divisome, an essential protein assembly required for septum synthesis and cell separation. The Z ring exists at mid-cell during a major part of the cell cycle without contracting. Here, we show that MreB and FtsZ of Escherichia coli interact directly and that this interaction is required for Z ring contraction. We further show that the MreB-FtsZ interaction is required for transfer of cell-wall biosynthetic enzymes from the lateral to the mature divisome, allowing cells to synthesise the septum. Our observations show that bacterial cell division is coupled to cell elongation via a direct and essential interaction between FtsZ and MreB.

  12. Nuclear size and cell division delay

    International Nuclear Information System (INIS)

    Bird, R.P.

    1986-01-01

    Radiation-induced division delay has been linked to damage at the nuclear envelope. Further, cells in G 2 phase are drastically arrested by high LET radiation such that single particles traversing cell nuclei may produce measurable division delay. A modest effort was initiated using two related cell lines of different size, near-diploid cells and near-tetraploid cells of Chinese hamster origin, to compare their sensitivity for radiation-induced division delay. If the nuclear surface is the critical target, then a larger nuclear cross-section presented to an alpha-particle beam should exhibit delay induced by a lesser particle fluence. Preliminary estimates of the extent of delay in asynchronous cultures following low doses of gamma-irradiation or of alpha-irradiation were made by in-situ observation of the time of onset of mitosis and by fixation and staining of cultures to determine the mitotic index as a function of time after irradiation. The basic approach to evaluating division delay will be to use Colecemid to accumulate mitotic cells over a period of time

  13. Historical Determinants of Regional Divisions of Georgia and their Implications for Territorial Governance

    Directory of Open Access Journals (Sweden)

    Mądry Cezary

    2016-06-01

    Full Text Available Georgia can be characterised by its turbulent history, centuries-old traditions, and a great ethnic diversity. This makes it necessary to include historical determinants, in addition to geopolitical and economic factors, when making a regional analysis of its territory and contemporary governance issues. Five stages of the development of the present territorial division of Georgia are distinguished. They have been identified by means of an analysis of key events (critical junctures of significance in the formation of its historical regions. Additionally, their influence at each of the three levels of the current territorial division of independent Georgia is discussed, in particular in the context of territorial governance.

  14. Asymmetric cell division of stem cells in the lung and other systems

    Directory of Open Access Journals (Sweden)

    Mohamed eBerika

    2014-07-01

    Full Text Available New insights have been added to identification, behavior and cellular properties of embryonic and tissue-specific stem cells over the last few years. The modes of stem cell division, asymmetric versus symmetric, are tightly regulated during development and regeneration. The proper choice of a stem cell to divide asymmetrically or symmetrically has great consequences for development and disease because inappropriate asymmetric division disrupts organ morphogenesis, whereas uncontrolled symmetric division induces tumorigenesis. Therefore, understanding the behavior of lung stem cells could identify innovative solutions for restoring normal morphogenesis and/or regeneration of different organs. In this concise review, we describe recent studies in our laboratory about the mode of division of lung epithelial stem cells. We also compare asymmetric cell division in the lung stem cells with other tissues in different organisms.

  15. Spatial pattern of cell geometry and cell-division orientation in zebrafish lens epithelium

    Directory of Open Access Journals (Sweden)

    Toshiaki Mochizuki

    2014-09-01

    Full Text Available Cell proliferation is a key regulator of tissue morphogenesis. We examined cell proliferation and cell division in zebrafish lens epithelium by visualizing cell-cycle phases and nuclear positions, using fluorescent-labeled geminin and histone proteins. Proliferation was low in the anterior region of lens epithelium and higher in the marginal zone anterior to the equator, suggesting that the proliferation zone, called the germinative zone, is formed in zebrafish lens. Interestingly, cell-division orientation was biased longitudinally in the anterior region, shifted from longitudinal to circumferential along the anterior–posterior axis of lens sphere, and was biased circumferentially in the peripheral region. These data suggest that cell-division orientation is spatially regulated in zebrafish lens epithelium. The Hertwig rule indicates that cells tend to divide along their long axes. Orientation of long axes and cell division were biased similarly in zebrafish lens epithelium, suggesting that cell geometry correlates with cell-division orientation. A cell adhesion molecule, E-cadherin, is expressed in lens epithelium. In a zebrafish e-cadherin mutant, the long axes and cell-division orientation were shifted more longitudinally. These data suggest that E-cadherin is required for the spatial pattern of cell geometry and cell-division orientation in zebrafish lens epithelium.

  16. Asymmetric cell division and its role in cell fate determination in the ...

    Indian Academy of Sciences (India)

    Supplementary figure 1. Light micrograph of an asymmetrically dividing T. indica cell at various time intervals. Progress over a 12 hr period, showing that the larger component does not undergo further division. (A) 0 h, cell division at an early stage. (B) 5 h, lower half of cell undergoing further division. (C) 12 h, differentiated ...

  17. Onset of cell division in maize germination: action of auxins

    International Nuclear Information System (INIS)

    de Jimenez, E.S.; Baiza, A.; Aguilar, R.

    1987-01-01

    Seed germination implies metabolic reactivation, synthesis of macromolecules and onset of cell division. During maize germination, meristematic tissues of embryos re-initiate cell division asynchronically. Since auxins are known to stimulate cell division, they asked how auxins might regulate cell cycle re-initiation. Embryonic tissues were incubated with and without auxins. A pulse of either 3 H-thymidine or 32 P-ortophosphate was given to the tissues. Mitotic indexes were determined and % of labeled mitotic cells recorded. Results indicated that meristematic cells re-initiate cell division either from G 1 or G 2 phases. Auxin stimulated differentially the cell division process of these cells. 32 P incorporation into cytoplasmic or nucleic histones was measured. Auxins stimulated this incorporation. Active turnover of histone phosphorylation occurred simultaneously to the cell division process. It is suggested that auxins might regulate the cell cycle by phosphorylation-dephosphorylation of histones

  18. Cell Division and Evolution of Biological Tissues

    Science.gov (United States)

    Rivier, Nicolas; Arcenegui-Siemens, Xavier; Schliecker, Gudrun

    A tissue is a geometrical, space-filling, random cellular network; it remains in this steady state while individual cells divide. Cell division (fragmentation) is a local, elementary topological transformation which establishes statistical equilibrium of the structure. Statistical equilibrium is characterized by observable relations (Lewis, Aboav) between cell shapes, sizes and those of their neighbours, obtained through maximum entropy and topological correlation extending to nearest neighbours only, i.e. maximal randomness. For a two-dimensional tissue (epithelium), the distribution of cell shapes and that of mother and daughter cells can be obtained from elementary geometrical and physical arguments, except for an exponential factor favouring division of larger cells, and exponential and combinatorial factors encouraging a most symmetric division. The resulting distributions are very narrow, and stationarity severely restricts the range of an adjustable structural parameter

  19. Quantitative regulation of B cell division destiny by signal strength.

    Science.gov (United States)

    Turner, Marian L; Hawkins, Edwin D; Hodgkin, Philip D

    2008-07-01

    Differentiation to Ab secreting and isotype-switched effector cells is tightly linked to cell division and therefore the degree of proliferation strongly influences the nature of the immune response. The maximum number of divisions reached, termed the population division destiny, is stochastically distributed in the population and is an important parameter in the quantitative outcome of lymphocyte responses. In this study, we further assessed the variables that regulate B cell division destiny in vitro in response to T cell- and TLR-dependent stimuli. Both the concentration and duration of stimulation were able to regulate the average maximum number of divisions undergone for each stimulus. Notably, a maximum division destiny was reached during provision of repeated saturating stimulation, revealing that an intrinsic limit to proliferation exists even under these conditions. This limit was linked directly to division number rather than time of exposure to stimulation and operated independently of the survival regulation of the cells. These results demonstrate that a B cell population's division destiny is regulable by the stimulatory conditions up to an inherent maximum value. Division destiny is a crucial parameter in regulating the extent of B cell responses and thereby also the nature of the immune response mounted.

  20. Asymmetries in Cell Division, Cell Size, and Furrowing in the Xenopus laevis Embryo.

    Science.gov (United States)

    Tassan, Jean-Pierre; Wühr, Martin; Hatte, Guillaume; Kubiak, Jacek

    2017-01-01

    Asymmetric cell divisions produce two daughter cells with distinct fate. During embryogenesis, this mechanism is fundamental to build tissues and organs because it generates cell diversity. In adults, it remains crucial to maintain stem cells. The enthusiasm for asymmetric cell division is not only motivated by the beauty of the mechanism and the fundamental questions it raises, but has also very pragmatic reasons. Indeed, misregulation of asymmetric cell divisions is believed to have dramatic consequences potentially leading to pathogenesis such as cancers. In diverse model organisms, asymmetric cell divisions result in two daughter cells, which differ not only by their fate but also in size. This is the case for the early Xenopus laevis embryo, in which the two first embryonic divisions are perpendicular to each other and generate two pairs of blastomeres, which usually differ in size: one pair of blastomeres is smaller than the other. Small blastomeres will produce embryonic dorsal structures, whereas the larger pair will evolve into ventral structures. Here, we present a speculative model on the origin of the asymmetry of this cell division in the Xenopus embryo. We also discuss the apparently coincident asymmetric distribution of cell fate determinants and cell-size asymmetry of the 4-cell stage embryo. Finally, we discuss the asymmetric furrowing during epithelial cell cytokinesis occurring later during Xenopus laevis embryo development.

  1. Cell division orientation is coupled to cell-cell adhesion by the E-cadherin/LGN complex

    NARCIS (Netherlands)

    Gloerich, Martijn; Bianchini, Julie M.; Siemers, Kathleen A.; Cohen, Daniel J.; Nelson, W. James

    2017-01-01

    Both cell-cell adhesion and oriented cell division play prominent roles in establishing tissue architecture, but it is unclear how they might be coordinated. Here, we demonstrate that the cell-cell adhesion protein E-cadherin functions as an instructive cue for cell division orientation. This is

  2. Genes involved in cell division in mycoplasmas

    Directory of Open Access Journals (Sweden)

    Frank Alarcón

    2007-01-01

    Full Text Available Bacterial cell division has been studied mainly in model systems such as Escherichia coli and Bacillus subtilis, where it is described as a complex process with the participation of a group of proteins which assemble into a multiprotein complex called the septal ring. Mycoplasmas are cell wall-less bacteria presenting a reduced genome. Thus, it was important to compare their genomes to analyze putative genes involved in cell division processes. The division and cell wall (dcw cluster, which in E. coli and B. subtilis is composed of 16 and 17 genes, respectively, is represented by only three to four genes in mycoplasmas. Even the most conserved protein, FtsZ, is not present in all mycoplasma genomes analyzed so far. A model for the FtsZ protein from Mycoplasma hyopneumoniae and Mycoplasma synoviae has been constructed. The conserved residues, essential for GTP/GDP binding, are present in FtsZ from both species. A strong conservation of hydrophobic amino acid patterns is observed, and is probably necessary for the structural stability of the protein when active. M. synoviae FtsZ presents an extended amino acid sequence at the C-terminal portion of the protein, which may participate in interactions with other still unknown proteins crucial for the cell division process.

  3. Lipid Cell Biology: A Focus on Lipids in Cell Division.

    Science.gov (United States)

    Storck, Elisabeth M; Özbalci, Cagakan; Eggert, Ulrike S

    2018-06-20

    Cells depend on hugely diverse lipidomes for many functions. The actions and structural integrity of the plasma membrane and most organelles also critically depend on membranes and their lipid components. Despite the biological importance of lipids, our understanding of lipid engagement, especially the roles of lipid hydrophobic alkyl side chains, in key cellular processes is still developing. Emerging research has begun to dissect the importance of lipids in intricate events such as cell division. This review discusses how these structurally diverse biomolecules are spatially and temporally regulated during cell division, with a focus on cytokinesis. We analyze how lipids facilitate changes in cellular morphology during division and how they participate in key signaling events. We identify which cytokinesis proteins are associated with membranes, suggesting lipid interactions. More broadly, we highlight key unaddressed questions in lipid cell biology and techniques, including mass spectrometry, advanced imaging, and chemical biology, which will help us gain insights into the functional roles of lipids.

  4. Plant cortical microtubule dynamics and cell division plane orientation

    NARCIS (Netherlands)

    Chakrabortty, Bandan

    2017-01-01

    This thesis work aimed at a better understanding of the molecular basis of oriented cell division in plant cell. As, the efficiency of plant morphogenesis depends on oriented cell division, this work should contribute towards a fundamental understanding of the molecular basis of efficient plant

  5. Overly long centrioles and defective cell division upon excess of the SAS-4-related protein CPAP.

    Science.gov (United States)

    Kohlmaier, Gregor; Loncarek, Jadranka; Meng, Xing; McEwen, Bruce F; Mogensen, Mette M; Spektor, Alexander; Dynlacht, Brian D; Khodjakov, Alexey; Gönczy, Pierre

    2009-06-23

    The centrosome is the principal microtubule organizing center (MTOC) of animal cells. Accurate centrosome duplication is fundamental for genome integrity and entails the formation of one procentriole next to each existing centriole, once per cell cycle. The procentriole then elongates to eventually reach the same size as the centriole. The mechanisms that govern elongation of the centriolar cylinder and their potential relevance for cell division are not known. Here, we show that the SAS-4-related protein CPAP is required for centrosome duplication in cycling human cells. Furthermore, we demonstrate that CPAP overexpression results in the formation of abnormally long centrioles. This also promotes formation of more than one procentriole in the vicinity of such overly long centrioles, eventually resulting in the presence of supernumerary MTOCs. This in turn leads to multipolar spindle assembly and cytokinesis defects. Overall, our findings suggest that centriole length must be carefully regulated to restrict procentriole number and thus ensure accurate cell division.

  6. Asymmetric cell division during T cell development controls downstream fate

    Science.gov (United States)

    Pham, Kim; Shimoni, Raz; Charnley, Mirren; Ludford-Menting, Mandy J.; Hawkins, Edwin D.; Ramsbottom, Kelly; Oliaro, Jane; Izon, David; Ting, Stephen B.; Reynolds, Joseph; Lythe, Grant; Molina-Paris, Carmen; Melichar, Heather; Robey, Ellen; Humbert, Patrick O.; Gu, Min

    2015-01-01

    During mammalian T cell development, the requirement for expansion of many individual T cell clones, rather than merely expansion of the entire T cell population, suggests a possible role for asymmetric cell division (ACD). We show that ACD of developing T cells controls cell fate through differential inheritance of cell fate determinants Numb and α-Adaptin. ACD occurs specifically during the β-selection stage of T cell development, and subsequent divisions are predominantly symmetric. ACD is controlled by interaction with stromal cells and chemokine receptor signaling and uses a conserved network of polarity regulators. The disruption of polarity by deletion of the polarity regulator, Scribble, or the altered inheritance of fate determinants impacts subsequent fate decisions to influence the numbers of DN4 cells arising after the β-selection checkpoint. These findings indicate that ACD enables the thymic microenvironment to orchestrate fate decisions related to differentiation and self-renewal. PMID:26370500

  7. Growth-arrest-specific protein 2 inhibits cell division in Xenopus embryos.

    Directory of Open Access Journals (Sweden)

    Tong Zhang

    Full Text Available Growth-arrest-specific 2 gene was originally identified in murine fibroblasts under growth arrest conditions. Furthermore, serum stimulation of quiescent, non-dividing cells leads to the down-regulation of gas2 and results in re-entry into the cell cycle. Cytoskeleton rearrangements are critical for cell cycle progression and cell division and the Gas2 protein has been shown to co-localize with actin and microtubules in interphase mammalian cells. Despite these findings, direct evidence supporting a role for Gas2 in the mechanism of cell division has not been reported.To determine whether the Gas2 protein plays a role in cell division, we over-expressed the full-length Gas2 protein and Gas2 truncations containing either the actin-binding CH domain or the tubulin-binding Gas2 domain in Xenopus laevis embryos. We found that both the full-length Gas2 protein and the Gas2 domain, but not the CH domain, inhibited cell division and resulted in multinucleated cells. The observation that Gas2 domain alone can arrest cell division suggests that Gas2 function is mediated by microtubule binding. Gas2 co-localized with microtubules at the cell cortex of Gas2-injected Xenopus embryos using cryo-confocal microscopy and co-sedimented with microtubules in cytoskeleton co-sedimentation assays. To investigate the mechanism of Gas2-induced cell division arrest, we showed, using a wound-induced contractile array assay, that Gas2 stabilized microtubules. Finally, electron microscopy studies demonstrated that Gas2 bundled microtubules into higher-order structures.Our experiments show that Gas2 inhibits cell division in Xenopus embryos. We propose that Gas2 function is mediated by binding and bundling microtubules, leading to cell division arrest.

  8. Asymmetric cell division requires specific mechanisms for adjusting global transcription.

    Science.gov (United States)

    Mena, Adriana; Medina, Daniel A; García-Martínez, José; Begley, Victoria; Singh, Abhyudai; Chávez, Sebastián; Muñoz-Centeno, Mari C; Pérez-Ortín, José E

    2017-12-01

    Most cells divide symmetrically into two approximately identical cells. There are many examples, however, of asymmetric cell division that can generate sibling cell size differences. Whereas physical asymmetric division mechanisms and cell fate consequences have been investigated, the specific problem caused by asymmetric division at the transcription level has not yet been addressed. In symmetrically dividing cells the nascent transcription rate increases in parallel to cell volume to compensate it by keeping the actual mRNA synthesis rate constant. This cannot apply to the yeast Saccharomyces cerevisiae, where this mechanism would provoke a never-ending increasing mRNA synthesis rate in smaller daughter cells. We show here that, contrarily to other eukaryotes with symmetric division, budding yeast keeps the nascent transcription rates of its RNA polymerases constant and increases mRNA stability. This control on RNA pol II-dependent transcription rate is obtained by controlling the cellular concentration of this enzyme. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

  9. Abnormal number cell division of human thyroid anaplastic carcinoma cell line, SW 1736

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    Keiichi Ikeda

    2015-12-01

    Full Text Available Cell division, during which a mother cell usually divides into two daughter cells during one cell cycle, is the most important physiological event of cell biology. We observed one-to-four cell division during imaging of live SW1736 human thyroid anaplastic carcinoma cells transfected with a plasmid expressing the hybrid protein of green fluorescent protein and histone 2B (plasmid eGFP-H2B. Analysis of the images revealed a mother cell divided into four daughter cells. And one of the abnormally divided daughter cells subsequently formed a dinucleate cell.

  10. Symmetric vs. asymmetric stem cell divisions: an adaptation against cancer?

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    Leili Shahriyari

    Full Text Available Traditionally, it has been held that a central characteristic of stem cells is their ability to divide asymmetrically. Recent advances in inducible genetic labeling provided ample evidence that symmetric stem cell divisions play an important role in adult mammalian homeostasis. It is well understood that the two types of cell divisions differ in terms of the stem cells' flexibility to expand when needed. On the contrary, the implications of symmetric and asymmetric divisions for mutation accumulation are still poorly understood. In this paper we study a stochastic model of a renewing tissue, and address the optimization problem of tissue architecture in the context of mutant production. Specifically, we study the process of tumor suppressor gene inactivation which usually takes place as a consequence of two "hits", and which is one of the most common patterns in carcinogenesis. We compare and contrast symmetric and asymmetric (and mixed stem cell divisions, and focus on the rate at which double-hit mutants are generated. It turns out that symmetrically-dividing cells generate such mutants at a rate which is significantly lower than that of asymmetrically-dividing cells. This result holds whether single-hit (intermediate mutants are disadvantageous, neutral, or advantageous. It is also independent on whether the carcinogenic double-hit mutants are produced only among the stem cells or also among more specialized cells. We argue that symmetric stem cell divisions in mammals could be an adaptation which helps delay the onset of cancers. We further investigate the question of the optimal fraction of stem cells in the tissue, and quantify the contribution of non-stem cells in mutant production. Our work provides a hypothesis to explain the observation that in mammalian cells, symmetric patterns of stem cell division seem to be very common.

  11. 78 FR 53194 - Advisory Group to the Internal Revenue Service Tax Exempt and Government Entities Division (TE/GE...

    Science.gov (United States)

    2013-08-28

    ... DEPARTMENT OF THE TREASURY Internal Revenue Service Advisory Group to the Internal Revenue Service Tax Exempt and Government Entities Division (TE/GE); Meeting AGENCY: Internal Revenue Service (IRS), Treasury. ACTION: Notice. SUMMARY: The Advisory Committee on Tax Exempt and Government Entities (ACT) will...

  12. Cell division cycle 20 overexpression predicts poor prognosis for patients with lung adenocarcinoma.

    Science.gov (United States)

    Shi, Run; Sun, Qi; Sun, Jing; Wang, Xin; Xia, Wenjie; Dong, Gaochao; Wang, Anpeng; Jiang, Feng; Xu, Lin

    2017-03-01

    The cell division cycle 20, a key component of spindle assembly checkpoint, is an essential activator of the anaphase-promoting complex. Aberrant expression of cell division cycle 20 has been detected in various human cancers. However, its clinical significance has never been deeply investigated in non-small-cell lung cancer. By analyzing The Cancer Genome Atlas database and using some certain online databases, we validated overexpression of cell division cycle 20 in both messenger RNA and protein levels, explored its clinical significance, and evaluated the prognostic role of cell division cycle 20 in non-small-cell lung cancer. Cell division cycle 20 expression was significantly correlated with sex (p = 0.003), histological classification (p overexpression of cell division cycle 20 was significantly associated with bigger primary tumor size (p = 0.0023), higher MKI67 level (r = 0.7618, p Overexpression of cell division cycle 20 is associated with poor prognosis in lung adenocarcinoma patients, and its overexpression can also be used to identify high-risk groups. In conclusion, cell division cycle 20 might serve as a potential biomarker for lung adenocarcinoma patients.

  13. Uncovering the link between malfunctions in Drosophila neuroblast asymmetric cell division and tumorigenesis

    Directory of Open Access Journals (Sweden)

    Kelsom Corey

    2012-11-01

    Full Text Available Abstract Asymmetric cell division is a developmental process utilized by several organisms. On the most basic level, an asymmetric division produces two daughter cells, each possessing a different identity or fate. Drosophila melanogaster progenitor cells, referred to as neuroblasts, undergo asymmetric division to produce a daughter neuroblast and another cell known as a ganglion mother cell (GMC. There are several features of asymmetric division in Drosophila that make it a very complex process, and these aspects will be discussed at length. The cell fate determinants that play a role in specifying daughter cell fate, as well as the mechanisms behind setting up cortical polarity within neuroblasts, have proved to be essential to ensuring that neurogenesis occurs properly. The role that mitotic spindle orientation plays in coordinating asymmetric division, as well as how cell cycle regulators influence asymmetric division machinery, will also be addressed. Most significantly, malfunctions during asymmetric cell division have shown to be causally linked with neoplastic growth and tumor formation. Therefore, it is imperative that the developmental repercussions as a result of asymmetric cell division gone awry be understood.

  14. Cell-Division Behavior in a Heterogeneous Swarm Environment.

    Science.gov (United States)

    Erskine, Adam; Herrmann, J Michael

    2015-01-01

    We present a system of virtual particles that interact using simple kinetic rules. It is known that heterogeneous mixtures of particles can produce particularly interesting behaviors. Here we present a two-species three-dimensional swarm in which a behavior emerges that resembles cell division. We show that the dividing behavior exists across a narrow but finite band of parameters and for a wide range of population sizes. When executed in a two-dimensional environment the swarm's characteristics and dynamism manifest differently. In further experiments we show that repeated divisions can occur if the system is extended by a biased equilibrium process to control the split of populations. We propose that this repeated division behavior provides a simple model for cell-division mechanisms and is of interest for the formation of morphological structure and to swarm robotics.

  15. Determination of cell division axes in the early embryogenesis of Caenorhabditis elegans

    OpenAIRE

    1987-01-01

    The establishment of cell division axes was examined in the early embryonic divisions of Caenorhabditis elegans. It has been shown previously that there are two different patterns of cleavage during early embryogenesis. In one set of cells, which undergo predominantly determinative divisions, the division axes are established successively in the same orientation, while division axes in the other set, which divide mainly proliferatively, have an orthogonal pattern of division. We have investig...

  16. Z ring as executor of bacterial cell division.

    Science.gov (United States)

    Dajkovic, Alex; Lutkenhaus, Joe

    2006-01-01

    It has become apparent that bacteria possess ancestors of the major eukaryotic cytoskeletal proteins. FtsZ, the ancestral homologue of tubulin, assembles into a cytoskeletal structure associated with cell division, designated the Z ring. Formation of the Z ring represents a major point of both spatial and temporal regulation of cell division. Here we discuss findings concerning the structure and the formation of the ring as well as its spatial and temporal regulation.

  17. Division of Labor in Biofilms: the Ecology of Cell Differentiation.

    Science.gov (United States)

    van Gestel, Jordi; Vlamakis, Hera; Kolter, Roberto

    2015-04-01

    The dense aggregation of cells on a surface, as seen in biofilms, inevitably results in both environmental and cellular heterogeneity. For example, nutrient gradients can trigger cells to differentiate into various phenotypic states. Not only do cells adapt physiologically to the local environmental conditions, but they also differentiate into cell types that interact with each other. This allows for task differentiation and, hence, the division of labor. In this article, we focus on cell differentiation and the division of labor in three bacterial species: Myxococcus xanthus, Bacillus subtilis, and Pseudomonas aeruginosa. During biofilm formation each of these species differentiates into distinct cell types, in some cases leading to cooperative interactions. The division of labor and the cooperative interactions between cell types are assumed to yield an emergent ecological benefit. Yet in most cases the ecological benefits have yet to be elucidated. A notable exception is M. xanthus, in which cell differentiation within fruiting bodies facilitates the dispersal of spores. We argue that the ecological benefits of the division of labor might best be understood when we consider the dynamic nature of both biofilm formation and degradation.

  18. A crucial step in cell division identified | Center for Cancer Research

    Science.gov (United States)

    When cell division doesn’t go according to plan, the resulting daughter cells can become unstable or even cancerous. A team of CCR investigators has now discovered a crucial step required for normal cell division to occur. Read more...

  19. ESCRT-III mediated cell division in Sulfolobus acidocaldarius –A reconstitution perspective

    Directory of Open Access Journals (Sweden)

    Tobias eHärtel

    2014-06-01

    Full Text Available In the framework of Synthetic Biology, it has become an intriguing question what would be the minimal representation of cell division machinery. Thus, it seems appropriate to compare how cell division is realized in different microorganisms. In particular, the cell division system of Crenarchaeota lacks certain proteins found in most bacteria and Euryarchaeota, such as FtsZ, MreB or the Min system. The Sulfolobaceae family encodes functional homologs of the eukaryotic proteins Vps4 and ESCRT-III. ESCRT-III is essential for several eukaryotic pathways, e.g. budding of intralumenal vesicles (ILVs, or cytokinesis, whereas Vps4 dissociates the ESCRT-III complex from the membrane. CdvA (Cell Division A is required for the recruitment of crenarchaeal ESCRT-III proteins to the membrane at mid-cell. The proteins polymerize and form a smaller structure during constriction. Thus, ESCRT-III mediated cell division in S. acidocaldarius shows functional analogies to the Z ring observed in prokaryotes like E. coli, which has recently begun to be reconstituted in vitro. In this short perspective, we discuss the possibility of building such an in vitro cell division system on basis of archaeal ESCRT-III.

  20. Periplasmic Acid Stress Increases Cell Division Asymmetry (Polar Aging of Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Michelle W Clark

    Full Text Available Under certain kinds of cytoplasmic stress, Escherichia coli selectively reproduce by distributing the newer cytoplasmic components to new-pole cells while sequestering older, damaged components in cells inheriting the old pole. This phenomenon is termed polar aging or cell division asymmetry. It is unknown whether cell division asymmetry can arise from a periplasmic stress, such as the stress of extracellular acid, which is mediated by the periplasm. We tested the effect of periplasmic acid stress on growth and division of adherent single cells. We tracked individual cell lineages over five or more generations, using fluorescence microscopy with ratiometric pHluorin to measure cytoplasmic pH. Adherent colonies were perfused continually with LBK medium buffered at pH 6.00 or at pH 7.50; the external pH determines periplasmic pH. In each experiment, cell lineages were mapped to correlate division time, pole age and cell generation number. In colonies perfused at pH 6.0, the cells inheriting the oldest pole divided significantly more slowly than the cells inheriting the newest pole. In colonies perfused at pH 7.50 (near or above cytoplasmic pH, no significant cell division asymmetry was observed. Under both conditions (periplasmic pH 6.0 or pH 7.5 the cells maintained cytoplasmic pH values at 7.2-7.3. No evidence of cytoplasmic protein aggregation was seen. Thus, periplasmic acid stress leads to cell division asymmetry with minimal cytoplasmic stress.

  1. The C. elegans engrailed homolog ceh-16 regulates the self-renewal expansion division of stem cell-like seam cells.

    Science.gov (United States)

    Huang, Xinxin; Tian, E; Xu, Yanhua; Zhang, Hong

    2009-09-15

    Stem cells undergo symmetric and asymmetric division to maintain the dynamic equilibrium of the stem cell pool and also to generate a variety of differentiated cells. The homeostatic mechanism controlling the choice between self-renewal and differentiation of stem cells is poorly understood. We show here that ceh-16, encoding the C. elegans ortholog of the transcription factor Engrailed, controls symmetric and asymmetric division of stem cell-like seam cells. Loss of function of ceh-16 causes certain seam cells, which normally undergo symmetric self-renewal expansion division with both daughters adopting the seam cell fate, to divide asymmetrically with only one daughter retaining the seam cell fate. The human engrailed homolog En2 functionally substitutes the role of ceh-16 in promoting self-renewal expansion division of seam cells. Loss of function of apr-1, encoding the C. elegans homolog of the Wnt signaling component APC, results in transformation of self-renewal maintenance seam cell division to self-renewal expansion division, leading to seam cell hyperplasia. The apr-1 mutation suppresses the seam cell division defect in ceh-16 mutants. Our study reveals that ceh-16 interacts with the Wnt signaling pathway to control the choice between self-renewal expansion and maintenance division and also demonstrates an evolutionarily conserved function of engrailed in promoting cell proliferation.

  2. Planar cell polarity signaling coordinates oriented cell division and cell rearrangement in clonally expanding growth plate cartilage.

    Science.gov (United States)

    Li, Yuwei; Li, Ang; Junge, Jason; Bronner, Marianne

    2017-10-10

    Both oriented cell divisions and cell rearrangements are critical for proper embryogenesis and organogenesis. However, little is known about how these two cellular events are integrated. Here we examine the linkage between these processes in chick limb cartilage. By combining retroviral-based multicolor clonal analysis with live imaging, the results show that single chondrocyte precursors can generate both single-column and multi-column clones through oriented division followed by cell rearrangements. Focusing on single column formation, we show that this stereotypical tissue architecture is established by a pivot-like process between sister cells. After mediolateral cell division, N-cadherin is enriched in the post-cleavage furrow; then one cell pivots around the other, resulting in stacking into a column. Perturbation analyses demonstrate that planar cell polarity signaling enables cells to pivot in the direction of limb elongation via this N-cadherin-mediated coupling. Our work provides new insights into the mechanisms generating appropriate tissue architecture of limb skeleton.

  3. Cell division requirement for activation of murine leukemia virus in cell culture by irradiation

    International Nuclear Information System (INIS)

    Otten, J.A.; Quarles, J.M.; Tennant, R.W.

    1976-01-01

    Actively dividing cultures of AKR mouse cells were exposed to relatively low dose-rates of γ radiation and tested for activation of endogenous leukemia viruses. Efficient and reproducible induction of virus was obtained with actively dividing cells, but cultures deprived of serum to inhibit cell division before and during γ irradiation were not activated, even when medium with serum was added immediately after irradiation. These results show that cell division was required for virus induction but that a stable intermediate similar to the state induced by halogenated pyrimidines was not formed. In actively dividing AKR cell cultures, virus activation appeared to be proportional to the dose of γ radiation; the estimated frequency of activation was 1-8 x 10 - 5 per exposed cell and the efficiency of activation was approximately 0.012 inductions per cell per rad. Other normal primary and established mouse cell cultures tested were not activated by γ radiation. The requirement of cell division for radiation and chemical activation may reflect some common mechanism for initiation of virus expression

  4. Movement of beta-irradiated epidermal basal cells to the spinous-granular layers in the absence of cell division

    International Nuclear Information System (INIS)

    Etoh, H.; Taguchi, Y.H.; Tabachnick, J.

    1975-01-01

    Guinea-pig epidermis was irradiated with 3000 rad of beta rays 1 hr after two injections of [ 3 H]thymidine 5 hr apart (labeled cells in S phase and G 2 phase) or 18 hr after injection (labeled early G 1 cells). In nonirradiated epidermis labeled basal cells divided within 24 hr with daughter cells remaining in the basal layer, and approximately 50 percent of the labeled cells moved into the spinal layer by the 3rd day. Cell division in nonirradiated epidermis diluted the number of silver grains/nucleus, and lightly labeled cells were found in the granular layer by day 7. Beta irradiation inhibited cell division but it did not slow the rate of transit (ca 8 days) of irradiated labeled cells from basal to granular layer, some of these remaining heavily labeled. Although cell division may play some role in upward movement of basal cells in normal epidermis detachment of a basal cell from the basement membrane and its transit to the granular layer is unimpaired in the absence of cell division. These findings suggest that some radioresistant metabolic function(s), not cell division, is responsible for upward movement of basal cells. (auth)

  5. Ploidy-Dependent Unreductional Meiotic Cell Division in Polyploid Wheat

    Science.gov (United States)

    Meiosis includes one round of DNA replication and two successive nuclear divisions, i.e. meiosis I (reductional) and meiosis II (equational). This specialized cell division reduces chromosomes in half and generates haploid gametes in sexual reproduction of eukaryotes. It ensures faithful transmiss...

  6. Planar cell polarity signaling coordinates oriented cell division and cell rearrangement in clonally expanding growth plate cartilage

    OpenAIRE

    Li, Yuwei; Li, Ang; Junge, Jason; Bronner, Marianne

    2017-01-01

    Both oriented cell divisions and cell rearrangements are critical for proper embryogenesis and organogenesis. However, little is known about how these two cellular events are integrated. Here we examine the linkage between these processes in chick limb cartilage. By combining retroviral-based multicolor clonal analysis with live imaging, the results show that single chondrocyte precursors can generate both single-column and multi-column clones through oriented division followed by cell rearra...

  7. Using stochastic cell division and death to probe minimal units of cellular replication

    Science.gov (United States)

    Chib, Savita; Das, Suman; Venkatesan, Soumya; Sai Narain Seshasayee, Aswin; Thattai, Mukund

    2018-03-01

    The invariant cell initiation mass measured in bacterial growth experiments has been interpreted as a minimal unit of cellular replication. Here we argue that the existence of such minimal units induces a coupling between the rates of stochastic cell division and death. To probe this coupling we tracked live and dead cells in Escherichia coli populations treated with a ribosome-targeting antibiotic. We find that the growth exponent from macroscopic cell growth or decay measurements can be represented as the difference of microscopic first-order cell division and death rates. The boundary between cell growth and decay, at which the number of live cells remains constant over time, occurs at the minimal inhibitory concentration (MIC) of the antibiotic. This state appears macroscopically static but is microscopically dynamic: division and death rates exactly cancel at MIC but each is remarkably high, reaching 60% of the antibiotic-free division rate. A stochastic model of cells as collections of minimal replicating units we term ‘widgets’ reproduces both steady-state and transient features of our experiments. Sub-cellular fluctuations of widget numbers stochastically drive each new daughter cell to one of two alternate fates, division or death. First-order division or death rates emerge as eigenvalues of a stationary Markov process, and can be expressed in terms of the widget’s molecular properties. High division and death rates at MIC arise due to low mean and high relative fluctuations of widget number. Isolating cells at the threshold of irreversible death might allow molecular characterization of this minimal replication unit.

  8. Mechanical Division of Cell-Sized Liposomes

    NARCIS (Netherlands)

    Deshpande, S.R.; Kerssemakers, J.W.J.; Dekker, C.

    2018-01-01

    Liposomes, self-assembled vesicles with a lipid-bilayer boundary similar to cell membranes, are extensively used in both fundamental and applied sciences. Manipulation of their physical properties, such as growth and division, may significantly expand their use as model systems in cellular and

  9. CD8 Memory Cells Develop Unique DNA Repair Mechanisms Favoring Productive Division.

    Science.gov (United States)

    Galgano, Alessia; Barinov, Aleksandr; Vasseur, Florence; de Villartay, Jean-Pierre; Rocha, Benedita

    2015-01-01

    Immune responses are efficient because the rare antigen-specific naïve cells are able to proliferate extensively and accumulate upon antigen stimulation. Moreover, differentiation into memory cells actually increases T cell accumulation, indicating improved productive division in secondary immune responses. These properties raise an important paradox: how T cells may survive the DNA lesions necessarily induced during their extensive division without undergoing transformation. We here present the first data addressing the DNA damage responses (DDRs) of CD8 T cells in vivo during exponential expansion in primary and secondary responses in mice. We show that during exponential division CD8 T cells engage unique DDRs, which are not present in other exponentially dividing cells, in T lymphocytes after UV or X irradiation or in non-metastatic tumor cells. While in other cell types a single DDR pathway is affected, all DDR pathways and cell cycle checkpoints are affected in dividing CD8 T cells. All DDR pathways collapse in secondary responses in the absence of CD4 help. CD8 T cells are driven to compulsive suicidal divisions preventing the propagation of DNA lesions. In contrast, in the presence of CD4 help all the DDR pathways are up regulated, resembling those present in metastatic tumors. However, this up regulation is present only during the expansion phase; i.e., their dependence on antigen stimulation prevents CD8 transformation. These results explain how CD8 T cells maintain genome integrity in spite of their extensive division, and highlight the fundamental role of DDRs in the efficiency of CD8 immune responses.

  10. Phenotypic plasticity and effects of selection on cell division symmetry in Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Uttara N Lele

    Full Text Available Aging has been demonstrated in unicellular organisms and is presumably due to asymmetric distribution of damaged proteins and other components during cell division. Whether the asymmetry-induced aging is inevitable or an adaptive and adaptable response is debated. Although asymmetric division leads to aging and death of some cells, it increases the effective growth rate of the population as shown by theoretical and empirical studies. Mathematical models predict on the other hand, that if the cells divide symmetrically, cellular aging may be delayed or absent, growth rate will be reduced but growth yield will increase at optimum repair rates. Therefore in nutritionally dilute (oligotrophic environments, where growth yield may be more critical for survival, symmetric division may get selected. These predictions have not been empirically tested so far. We report here that Escherichia coli grown in oligotrophic environments had greater morphological and functional symmetry in cell division. Both phenotypic plasticity and genetic selection appeared to shape cell division time asymmetry but plasticity was lost on prolonged selection. Lineages selected on high nutrient concentration showed greater frequency of presumably old or dead cells. Further, there was a negative correlation between cell division time asymmetry and growth yield but there was no significant correlation between asymmetry and growth rate. The results suggest that cellular aging driven by asymmetric division may not be hardwired but shows substantial plasticity as well as evolvability in response to the nutritional environment.

  11. Modelling cell division and endoreduplication in tomato fruit pericarp

    NARCIS (Netherlands)

    Apri, M.; Kromdijk, J.; Visser, de P.H.B.; Gee, de M.; Molenaar, J.

    2014-01-01

    In many developing plant tissues and organs, differentiating cells switch from the classical cell cycle to an alternative partial cycle. This partial cycle bypasses mitosis and allows for multiple rounds of genome duplication without cell division, giving rise to cells with high ploidy numbers. This

  12. INO80 Chromatin Remodeling Coordinates Metabolic Homeostasis with Cell Division

    Directory of Open Access Journals (Sweden)

    Graeme J. Gowans

    2018-01-01

    Full Text Available Adaptive survival requires the coordination of nutrient availability with expenditure of cellular resources. For example, in nutrient-limited environments, 50% of all S. cerevisiae genes synchronize and exhibit periodic bursts of expression in coordination with respiration and cell division in the yeast metabolic cycle (YMC. Despite the importance of metabolic and proliferative synchrony, the majority of YMC regulators are currently unknown. Here, we demonstrate that the INO80 chromatin-remodeling complex is required to coordinate respiration and cell division with periodic gene expression. Specifically, INO80 mutants have severe defects in oxygen consumption and promiscuous cell division that is no longer coupled with metabolic status. In mutant cells, chromatin accessibility of periodic genes, including TORC1-responsive genes, is relatively static, concomitant with severely attenuated gene expression. Collectively, these results reveal that the INO80 complex mediates metabolic signaling to chromatin to restrict proliferation to metabolically optimal states.

  13. An Equatorial Contractile Mechanism Drives Cell Elongation but not Cell Division

    Science.gov (United States)

    Denker, Elsa; Bhattachan, Punit; Deng, Wei; Mathiesen, Birthe T.; Jiang, Di

    2014-01-01

    Cell shape changes and proliferation are two fundamental strategies for morphogenesis in animal development. During embryogenesis of the simple chordate Ciona intestinalis, elongation of individual notochord cells constitutes a crucial stage of notochord growth, which contributes to the establishment of the larval body plan. The mechanism of cell elongation is elusive. Here we show that although notochord cells do not divide, they use a cytokinesis-like actomyosin mechanism to drive cell elongation. The actomyosin network forming at the equator of each notochord cell includes phosphorylated myosin regulatory light chain, α-actinin, cofilin, tropomyosin, and talin. We demonstrate that cofilin and α-actinin are two crucial components for cell elongation. Cortical flow contributes to the assembly of the actomyosin ring. Similar to cytokinetic cells, membrane blebs that cause local contractions form at the basal cortex next to the equator and participate in force generation. We present a model in which the cooperation of equatorial actomyosin ring-based constriction and bleb-associated contractions at the basal cortex promotes cell elongation. Our results demonstrate that a cytokinesis-like contractile mechanism is co-opted in a completely different developmental scenario to achieve cell shape change instead of cell division. We discuss the occurrences of actomyosin rings aside from cell division, suggesting that circumferential contraction is an evolutionally conserved mechanism to drive cell or tissue elongation. PMID:24503569

  14. Mammalian aPKC/Par polarity complex mediated regulation of epithelial division orientation and cell fate

    Energy Technology Data Exchange (ETDEWEB)

    Vorhagen, Susanne; Niessen, Carien M., E-mail: carien.niessen@uni-koeln.de

    2014-11-01

    Oriented cell division is a key regulator of tissue architecture and crucial for morphogenesis and homeostasis. Balanced regulation of proliferation and differentiation is an essential property of tissues not only to drive morphogenesis but also to maintain and restore homeostasis. In many tissues orientation of cell division is coupled to the regulation of differentiation producing daughters with similar (symmetric cell division, SCD) or differential fate (asymmetric cell division, ACD). This allows the organism to generate cell lineage diversity from a small pool of stem and progenitor cells. Division orientation and/or the ratio of ACD/SCD need to be tightly controlled. Loss of orientation or an altered ratio can promote overgrowth, alter tissue architecture and induce aberrant differentiation, and have been linked to morphogenetic diseases, cancer and aging. A key requirement for oriented division is the presence of a polarity axis, which can be established through cell intrinsic and/or extrinsic signals. Polarity proteins translate such internal and external cues to drive polarization. In this review we will focus on the role of the polarity complex aPKC/Par3/Par6 in the regulation of division orientation and cell fate in different mammalian epithelia. We will compare the conserved function of this complex in mitotic spindle orientation and distribution of cell fate determinants and highlight common and differential mechanisms in which this complex is used by tissues to adapt division orientation and cell fate to the specific properties of the epithelium.

  15. Primitive human hematopoietic cells give rise to differentially specified daughter cells upon their initial cell division.

    NARCIS (Netherlands)

    Giebel, B.; Zhang, T.; Beckmann, J.; Spanholtz, J.; Wernet, P.; Ho, A.; Punzel, M.

    2006-01-01

    It is often predicted that stem cells divide asymmetrically, creating a daughter cell that maintains the stem-cell capacity, and 1 daughter cell committed to differentiation. While asymmetric stem-cell divisions have been proven to occur in model organisms (eg, in Drosophila), it remains illusive

  16. Chromosome replication, cell growth, division and shape: a personal perspective

    Directory of Open Access Journals (Sweden)

    Arieh eZaritsky

    2015-08-01

    Full Text Available The origins of Molecular Biology and Bacterial Physiology are reviewed, from our personal standpoints, emphasizing the coupling between bacterial growth, chromosome replication and cell division, dimensions and shape. Current knowledge is discussed with historical perspective, summarizing past and present achievements and enlightening ideas for future studies. An interactive simulation program of the Bacterial Cell Division Cycle (BCD, described as The Central Dogma in Bacteriology, is briefly represented. The coupled process of transcription/translation of genes encoding membrane proteins and insertion into the membrane (so-called transertion is invoked as the functional relationship between the only two unique macromolecules in the cell, DNA and peptidoglycan embodying the nucleoid and the sacculus respectively. We envision that nucleoid complexity, defined as the weighted-mean DNA content associated with the replication terminus, is directly related to cell shape through the transertion process. Accordingly, the primary signal for cell division transmitted by DNA dynamics (replication, transcription and segregation to the peptidoglycan biosynthetic machinery is of a physico-chemical nature, eg stress in the plasma membrane, relieving nucleoid occlusion in the cell's center hence enabling the divisome to assemble and function between segregated daughter nucleoids.

  17. Formation of a cylindrical bridge in cell division

    Science.gov (United States)

    Citron, Daniel; Schmidt, Laura E.; Reichl, Elizabeth; Ren, Yixin; Robinson, Douglas; Zhang, Wendy W.

    2007-11-01

    In nature, the shape transition associated with the division of a mother cell into two daughter cells proceeds via a variety of routes. In the cylinder-thinning route, which has been observed in Dictyostelium and most animal cells, the mother cell first forms a broad bridge-like region, also known as a furrow, between two daughter cells. The furrow then rapidly evolves into a cylindrical bridge, which thins and eventually severs the mother cell into two. The fundamental mechanism underlying this division route is not understood. Recent experiments on Dictyostelium found that, while the cylinder-thinning route persists even when key actin cross-linking proteins are missing, it is disrupted by the removal of force-generating myosin-II proteins. Other measurements revealed that mutant cells lacking myosin-II have a much more uniform tension over the cell surface than wild-type cells. This suggests that tension variation may be important. Here we use a fluid model, previously shown to reproduce the thinning dynamics [Zhang & Robinson, PNAS 102, 7186 (2005)], to test this idea. Consistent with the experiments, the model shows that the cylinder formation process occurs regardless of the exact viscoelastic properties of the cell. In contrast to the experiments, a tension variation in the model hinders, rather then expedites, the cylinder formation.

  18. Cell division control by the Chromosomal Passenger Complex

    Energy Technology Data Exchange (ETDEWEB)

    Waal, Maike S. van der; Hengeveld, Rutger C.C.; Horst, Armando van der; Lens, Susanne M.A., E-mail: s.m.a.lens@umcutrecht.nl

    2012-07-15

    The Chromosomal Passenger Complex (CPC) consisting of Aurora B kinase, INCENP, Survivin and Borealin, is essential for genomic stability by controlling multiple processes during both nuclear and cytoplasmic division. In mitosis it ensures accurate segregation of the duplicated chromosomes by regulating the mitotic checkpoint, destabilizing incorrectly attached spindle microtubules and by promoting the axial shortening of chromosomal arms in anaphase. During cytokinesis the CPC most likely prevents chromosome damage by imposing an abscission delay when a chromosome bridge connects the two daughter cells. Moreover, by controlling proper cytoplasmic division, the CPC averts tetraploidization. This review describes recent insights on how the CPC is capable of conducting its various functions in the dividing cell to ensure chromosomal stability.

  19. Are There Really Animals Like That? No Cell Division.

    Science.gov (United States)

    Blackwelder, R. E.; Garoian, G. S.

    1984-01-01

    Provides examples of animals in which growth occurs without cell division. Indicates that this phenomenon (called cell constancy or eutely) is an oddity of development that has arisen independently in several animal groups. (JN)

  20. Modeling of Complex Life Cycle Prediction Based on Cell Division

    Directory of Open Access Journals (Sweden)

    Fucheng Zhang

    2017-01-01

    Full Text Available Effective fault diagnosis and reasonable life expectancy are of great significance and practical engineering value for the safety, reliability, and maintenance cost of equipment and working environment. At present, the life prediction methods of the equipment are equipment life prediction based on condition monitoring, combined forecasting model, and driven data. Most of them need to be based on a large amount of data to achieve the problem. For this issue, we propose learning from the mechanism of cell division in the organism. We have established a moderate complexity of life prediction model across studying the complex multifactor correlation life model. In this paper, we model the life prediction of cell division. Experiments show that our model can effectively simulate the state of cell division. Through the model of reference, we will use it for the equipment of the complex life prediction.

  1. FtsZ-less prokaryotic cell division as well as FtsZ- and dynamin-less chloroplast and non-photosynthetic plastid division

    Directory of Open Access Journals (Sweden)

    Shin-Ya eMiyagishima

    2014-09-01

    Full Text Available The chloroplast division machinery is a mixture of a stromal FtsZ-based complex descended from a cyanobacterial ancestor of chloroplasts and a cytosolic dynamin-related protein (DRP 5B-based complex derived from the eukaryotic host. Molecular genetic studies have shown that each component of the division machinery is normally essential for normal chloroplast division. However, several exceptions have been found. In the absence of the FtsZ ring, nonphotosynthetic plastids are able to proliferate, likely by elongation and budding. Depletion of DRP5B impairs, but does not stop chloroplast division. Chloroplasts in glaucophytes, which possesses a peptidoglycan (PG layer, divide without DRP5B. Certain parasitic eukaryotes possess nonphotosynthetic plastids of secondary endosymbiotic origin, but neither FtsZ nor DRP5B is encoded in their genomes. Elucidation of the FtsZ- and/or DRP5B-less chloroplast division mechanism will lead to a better understanding of the function and evolution of the chloroplast division machinery and the finding of the as-yet-unknown mechanism that is likely involved in chloroplast division. Recent studies have shown that FtsZ was lost from a variety of prokaryotes, many of which lost PG by regressive evolution. In addition, even some of the FtsZ-bearing bacteria are able to divide when FtsZ and PG are depleted experimentally. In some cases, alternative mechanisms for cell division, such as budding by an increase of the cell surface-to-volume ratio, are proposed. Although PG is believed to have been lost from chloroplasts other than in glaucophytes, there is some indirect evidence for the existence of PG in chloroplasts. Such information is also useful for understanding how nonphotosynthetic plastids are able to divide in FtsZ-depleted cells and the reason for the retention of FtsZ in chloroplast division. Here we summarize information to facilitate analyses of FtsZ- and/or DRP5B-less chloroplast and nonphotosynthetic plastid

  2. Interdependence of bacterial cell division and genome segregation and its potential in drug development.

    Science.gov (United States)

    Misra, Hari S; Maurya, Ganesh K; Chaudhary, Reema; Misra, Chitra S

    2018-03-01

    Cell division and genome segregation are mutually interdependent processes, which are tightly linked with bacterial multiplication. Mechanisms underlying cell division and the cellular machinery involved are largely conserved across bacteria. Segregation of genome elements on the other hand, follows different pathways depending upon its type and the functional components encoded on these elements. Small molecules, that are known to inhibit cell division and/or resolution of intertwined circular chromosome and maintenace of DNA topology have earlier been tested as antibacterial agents. The utility of such drugs in controlling bacterial infections has witnessed only partial success, possibly due to functional redundancy associated with targeted components. However, in due course, literature has grown with newer information. This review has brought forth some recent findings on bacterial cell division with special emphasis on crosstalk between cell division and genome segregation that could be explored as novel targets in drug development. Copyright © 2018 Elsevier GmbH. All rights reserved.

  3. Label-free quantitative cell division monitoring of endothelial cells by digital holographic microscopy

    Science.gov (United States)

    Kemper, Björn; Bauwens, Andreas; Vollmer, Angelika; Ketelhut, Steffi; Langehanenberg, Patrik; Müthing, Johannes; Karch, Helge; von Bally, Gert

    2010-05-01

    Digital holographic microscopy (DHM) enables quantitative multifocus phase contrast imaging for nondestructive technical inspection and live cell analysis. Time-lapse investigations on human brain microvascular endothelial cells demonstrate the use of DHM for label-free dynamic quantitative monitoring of cell division of mother cells into daughter cells. Cytokinetic DHM analysis provides future applications in toxicology and cancer research.

  4. Analytical model for macromolecular partitioning during yeast cell division

    International Nuclear Information System (INIS)

    Kinkhabwala, Ali; Khmelinskii, Anton; Knop, Michael

    2014-01-01

    Asymmetric cell division, whereby a parent cell generates two sibling cells with unequal content and thereby distinct fates, is central to cell differentiation, organism development and ageing. Unequal partitioning of the macromolecular content of the parent cell — which includes proteins, DNA, RNA, large proteinaceous assemblies and organelles — can be achieved by both passive (e.g. diffusion, localized retention sites) and active (e.g. motor-driven transport) processes operating in the presence of external polarity cues, internal asymmetries, spontaneous symmetry breaking, or stochastic effects. However, the quantitative contribution of different processes to the partitioning of macromolecular content is difficult to evaluate. Here we developed an analytical model that allows rapid quantitative assessment of partitioning as a function of various parameters in the budding yeast Saccharomyces cerevisiae. This model exposes quantitative degeneracies among the physical parameters that govern macromolecular partitioning, and reveals regions of the solution space where diffusion is sufficient to drive asymmetric partitioning and regions where asymmetric partitioning can only be achieved through additional processes such as motor-driven transport. Application of the model to different macromolecular assemblies suggests that partitioning of protein aggregates and episomes, but not prions, is diffusion-limited in yeast, consistent with previous reports. In contrast to computationally intensive stochastic simulations of particular scenarios, our analytical model provides an efficient and comprehensive overview of partitioning as a function of global and macromolecule-specific parameters. Identification of quantitative degeneracies among these parameters highlights the importance of their careful measurement for a given macromolecular species in order to understand the dominant processes responsible for its observed partitioning

  5. Molecular Programs Underlying Asymmetric Stem Cell Division and Their Disruption in Malignancy.

    Science.gov (United States)

    Mukherjee, Subhas; Brat, Daniel J

    2017-01-01

    Asymmetric division of stem cells is a highly conserved and tightly regulated process by which a single stem cell produces two unequal daughter cells. One retains its stem cell identity while the other becomes specialized through a differentiation program and loses stem cell properties. Coordinating these events requires control over numerous intra- and extracellular biological processes and signaling networks. In the initial stages, critical events include the compartmentalization of fate determining proteins within the mother cell and their subsequent passage to the appropriate daughter cell in order to direct their destiny. Disturbance of these events results in an altered dynamic of self-renewing and differentiation within the cell population, which is highly relevant to the growth and progression of cancer. Other critical events include proper asymmetric spindle assembly, extrinsic regulation through micro-environmental cues, and non-canonical signaling networks that impact cell division and fate determination. In this review, we discuss mechanisms that maintain the delicate balance of asymmetric cell division in normal tissues and describe the current understanding how some of these mechanisms are deregulated in cancer.

  6. A Bistable Circuit Involving SCARECROW-RETINOBLASTOMA Integrates Cues to Inform Asymmetric Stem Cell Division

    Science.gov (United States)

    Cruz-Ramírez, Alfredo; Díaz-Triviño, Sara; Blilou, Ikram; Grieneisen, Verônica A.; Sozzani, Rosangela; Zamioudis, Christos; Miskolczi, Pál; Nieuwland, Jeroen; Benjamins, René; Dhonukshe, Pankaj; Caballero-Pérez, Juan; Horvath, Beatrix; Long, Yuchen; Mähönen, Ari Pekka; Zhang, Hongtao; Xu, Jian; Murray, James A.H.; Benfey, Philip N.; Bako, Laszlo; Marée, Athanasius F.M.; Scheres, Ben

    2012-01-01

    SUMMARY In plants, where cells cannot migrate, asymmetric cell divisions (ACDs) must be confined to the appropriate spatial context. We investigate tissue-generating asymmetric divisions in a stem cell daughter within the Arabidopsis root. Spatial restriction of these divisions requires physical binding of the stem cell regulator SCARECROW (SCR) by the RETINOBLASTOMA-RELATED (RBR) protein. In the stem cell niche, SCR activity is counteracted by phosphorylation of RBR through a cyclinD6;1-CDK complex. This cyclin is itself under transcriptional control of SCR and its partner SHORT ROOT (SHR), creating a robust bistable circuit with either high or low SHR-SCR complex activity. Auxin biases this circuit by promoting CYCD6;1 transcription. Mathematical modeling shows that ACDs are only switched on after integration of radial and longitudinal information, determined by SHR and auxin distribution, respectively. Coupling of cell-cycle progression to protein degradation resets the circuit, resulting in a “flip flop” that constrains asymmetric cell division to the stem cell region. PMID:22921914

  7. Radiomimetic effect of cisplatin on cucumber root development: the relationship between cell division and cell growth

    Energy Technology Data Exchange (ETDEWEB)

    Dubrovsky, J. G. [Division of Experimental Biology, Center for Biological Research (CIB), PO Box 128, La Paz, BCS 23000 (Mexico)

    1993-07-01

    Cisplatin [DDP, cis-dichlorodiammine platinum (II)], a strong cytostatic and antineoplastic agent, was tested on seedlings of cucumber Cucumis sativus L. for its general effect on root development and its particular effects on root cell division and cell growth. DDP was characterized as a radiomimetic compound since both DDP (1·3 × 10{sup -5} M) and γ-irradiation (2·5-10 kGy) drastically and irreversibly stopped development of embryonic lateral root primordia (LRPs) in the radicle by inhibiting both mitotic activity and cell growth. In 20% of the LRPs of DDP-treated roots, cells did not divide at all. Dividing cells completed no more than two cell cycles. These effects were specific because when DDP was available to the roots only at the onset of cell division, cell proliferation and cell growth were similar to that produced by constant incubation. Neither DDP nor γ-irradiation affected non-meristematic cell elongation. It was concluded that cell growth of meristematic cells is closely related to cell division. However, non-meristematic cell growth is independent of DNA damage. This suggests DDP as a tool to reveal these autonomous processes in plants development and to detect tissue compartments in mature plant embryos which contain potentially non-meristematic cells. (author)

  8. Live birth potential of good morphology and vitrified blastocysts presenting abnormal cell divisions

    DEFF Research Database (Denmark)

    Azzarello, Antonino; Høst, Thomas; Hay-Schmidt, Anders

    2017-01-01

    a lower live birth rate (17.0%) than blastocyst with solely regular cell divisions (29.3%). ACDs could occur at more than one cell division in the same good morphology blastocyst. Reported as independent events, we observed ACDs occurring more frequently at the later cell cycles (1st: 1.3%; 2nd: 8.0%; 3rd...

  9. Arabidopsis brassinosteroid biosynthetic mutant dwarf7-1 exhibits slower rates of cell division and shoot induction

    Directory of Open Access Journals (Sweden)

    Schulz Burkhard

    2010-12-01

    Full Text Available Abstract Background Plant growth depends on both cell division and cell expansion. Plant hormones, including brassinosteroids (BRs, are central to the control of these two cellular processes. Despite clear evidence that BRs regulate cell elongation, their roles in cell division have remained elusive. Results Here, we report results emphasizing the importance of BRs in cell division. An Arabidopsis BR biosynthetic mutant, dwarf7-1, displayed various characteristics attributable to slower cell division rates. We found that the DWARF4 gene which encodes for an enzyme catalyzing a rate-determining step in the BR biosynthetic pathways, is highly expressed in the actively dividing callus, suggesting that BR biosynthesis is necessary for dividing cells. Furthermore, dwf7-1 showed noticeably slower rates of callus growth and shoot induction relative to wild-type control. Flow cytometric analyses of the nuclei derived from either calli or intact roots revealed that the cell division index, which was represented as the ratio of cells at the G2/M vs. G1 phases, was smaller in dwf7-1 plants. Finally, we found that the expression levels of the genes involved in cell division and shoot induction, such as PROLIFERATING CELL NUCLEAR ANTIGEN2 (PCNA2 and ENHANCER OF SHOOT REGENERATION2 (ESR2, were also lower in dwf7-1 as compared with wild type. Conclusions Taken together, results of callus induction, shoot regeneration, flow cytometry, and semi-quantitative RT-PCR analysis suggest that BRs play important roles in both cell division and cell differentiation in Arabidopsis.

  10. Tumor-Initiating Label-Retaining Cancer Cells in Human Gastrointestinal Cancers Undergo Asymmetric Cell Division

    Science.gov (United States)

    Xin, Hong-Wu; Hari, Danielle M.; Mullinax, John E.; Ambe, Chenwi M.; Koizumi, Tomotake; Ray, Satyajit; Anderson, Andrew J.; Wiegand, Gordon W.; Garfield, Susan H.; Thorgeirsson, Snorri S.; Avital, Itzhak

    2012-01-01

    Label-retaining cells (LRCs) have been proposed to represent adult tissue stem cells. LRCs are hypothesized to result from either slow cycling or asymmetric cell division (ACD). However, the stem cell nature and whether LRC undergo ACD remain controversial. Here, we demonstrate label-retaining cancer cells (LRCCs) in several gastrointestinal (GI) cancers including fresh surgical specimens. Using a novel method for isolation of live LRCC, we demonstrate that a subpopulation of LRCC is actively dividing and exhibits stem cells and pluripotency gene expression profiles. Using real-time confocal microscopic cinematography, we show live LRCC undergoing asymmetric nonrandom chromosomal cosegregation LRC division. Importantly, LRCCs have greater tumor-initiating capacity than non-LRCCs. Based on our data and that cancers develop in tissues that harbor normal-LRC, we propose that LRCC might represent a novel population of GI stem-like cancer cells. LRCC may provide novel mechanistic insights into the biology of cancer and regenerative medicine and present novel targets for cancer treatment. PMID:22331764

  11. Control of cell division and radiation injury in mouse skin

    International Nuclear Information System (INIS)

    Yamaguchi, Takeo

    1974-01-01

    The method for determining the inhibitors of cell division (chalone-adrenalin system) in the irradiated epidermis and blood was developed using the epidermis of mouse ear conch during the cure of wounds (in vivo), and the epidermis cultured for a long period (in vitro). The whole body was irradiated with 200KV, 20 mA x-rays of 96 R/min filtered by 0.5 mmCu + 0.5 mmAl. Chalone, which is a physiologically intrinsic substance to control the proliferation, inhibits the DNA synthesis. From changes in cell division with time, chalone in the epidermis is considered to inhibit each process from G 2 to M, from G 2 to S, from G 1 to S. Adrenalin is indispensable when epidermal chalone acts the inhibition of cell division. Chalone activities in the epidermis irradiated with almost lethal doses were decreased. Factors to inhibit the proliferation of the epidermis by the potentiation of chalone and adrenalin are present in sera of animals irradiated to x-rays. (Serizawa, K.)

  12. Partnerships in global health and collaborative governance: lessons learnt from the Division of Tropical and Humanitarian Medicine at the Geneva University Hospitals.

    Science.gov (United States)

    Beran, David; Aebischer Perone, Sigiriya; Alcoba, Gabriel; Bischoff, Alexandre; Bussien, Claire-Lise; Eperon, Gilles; Hagon, Olivier; Heller, Olivia; Jacquerioz Bausch, Frédérique; Perone, Nicolas; Vogel, Thomas; Chappuis, François

    2016-04-29

    In 2007 the "Crisp Report" on international partnerships increased interest in Northern countries on the way their links with Southern partners operated. Since its establishment in 2007 the Division of Tropical and Humanitarian Medicine at the Geneva University Hospitals has developed a variety of partnerships. Frameworks to assess these partnerships are needed and recent attention in the field of public management on collaborative governance may provide a useful approach for analyzing international collaborations. Projects of the Division of Tropical and Humanitarian Medicine were analyzed by collaborators within the Division using the model proposed by Emerson and colleagues for collaborative governance, which comprises different components that assess the collaborative process. International projects within the Division of Tropical and Humanitarian Medicine can be divided into four categories: Human resource development; Humanitarian response; Neglected Tropical Diseases and Noncommunicable diseases. For each of these projects there was a clear leader from the Division of Tropical and Humanitarian Medicine as well as a local counterpart. These individuals were seen as leaders both due to their role in establishing the collaboration as well as their technical expertise. Across these projects the actual partners vary greatly. This diversity means a wide range of contributions to the collaboration, but also complexity in managing different interests. A common definition of the collaborative aims in each of the projects is both a formal and informal process. Legal, financial and administrative aspects of the collaboration are the formal elements. These can be a challenge based on different administrative requirements. Friendship is part of the informal aspects and helps contribute to a relationship that is not exclusively professional. Using collaborative governance allows the complexity of managing partnerships to be presented. The framework used highlights the

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

    Directory of Open Access Journals (Sweden)

    Stefania Castagnetti

    2010-10-01

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

  14. Heparan sulfate and cell division

    Directory of Open Access Journals (Sweden)

    Porcionatto M.A.

    1999-01-01

    Full Text Available Heparan sulfate is a component of vertebrate and invertebrate tissues which appears during the cytodifferentiation stage of embryonic development. Its structure varies according to the tissue and species of origin and is modified during neoplastic transformation. Several lines of experimental evidence suggest that heparan sulfate plays a role in cellular recognition, cellular adhesion and growth control. Heparan sulfate can participate in the process of cell division in two distinct ways, either as a positive or negative modulator of cellular proliferation, or as a response to a mitogenic stimulus.

  15. Correlation between cationic lipid-based transfection and cell division

    Energy Technology Data Exchange (ETDEWEB)

    Kirchenbuechler, Inka; Kirchenbuechler, David; Elbaum, Michael, E-mail: michael@elbaum.ac.il

    2016-07-01

    We evaluate the temporal relation between protein expression by cationic lipid-mediated transfection and cell division using time lapse fluorescence microscopy. Detailed image analysis provides new insights on the single cell level while simultaneously achieving appropriate statistics. Earlier evidence by less direct methods such as flow cytometry indicates a primary route for transfection involving nuclear envelope breakdown, but also suggests the existence of a pathway independent of mitosis. We confirm and quantify both mechanisms. We found the timing for successful transfection to be unexpectedly flexible, contrary to assertions of a narrow time window. Specifically, cells dividing more than 24 h after exposure to the transfection medium express the probed protein at a comparable level to cells in a mitotic state during or shortly after transfection. This finding can have a profound impact on the guidance and development of non-viral gene delivery materials. - Highlights: • Cationic lipid-based transfection supports protein expression without cell division. • Protein expression is unrelated to cell cycle status at the time of transfection. • Time-lapse imaging provides direct evaluation without statistical averaging. • Lipoplex dissociation is a likely target for improvement of transfection efficiency.

  16. Drosophila Sulf1 is required for the termination of intestinal stem cell division during regeneration.

    Science.gov (United States)

    Takemura, Masahiko; Nakato, Hiroshi

    2017-01-15

    Stem cell division is activated to trigger regeneration in response to tissue damage. The molecular mechanisms by which this stem cell mitotic activity is properly repressed at the end of regeneration are poorly understood. Here, we show that a specific modification of heparan sulfate is crucial for regulating Drosophila intestinal stem cell (ISC) division during normal midgut homeostasis and regeneration. Loss of the extracellular heparan sulfate endosulfatase Sulf1 resulted in increased ISC division during normal homeostasis, which was caused by upregulation of mitogenic signaling including the JAK-STAT, EGFR and Hedgehog pathways. Using a regeneration model, we found that ISCs failed to properly halt division at the termination stage in Sulf1 mutants, showing that Sulf1 is required for terminating ISC division at the end of regeneration. We propose that post-transcriptional regulation of mitogen signaling by heparan sulfate structural modifications provides a new regulatory step for precise temporal control of stem cell activity during regeneration. © 2017. Published by The Company of Biologists Ltd.

  17. LocZ Is a New Cell Division Protein Involved in Proper Septum Placement in Streptococcus pneumoniae

    Science.gov (United States)

    Holečková, Nela; Molle, Virginie; Buriánková, Karolína; Benada, Oldřich; Kofroňová, Olga; Ulrych, Aleš; Branny, Pavel

    2014-01-01

    ABSTRACT How bacteria control proper septum placement at midcell, to guarantee the generation of identical daughter cells, is still largely unknown. Although different systems involved in the selection of the division site have been described in selected species, these do not appear to be widely conserved. Here, we report that LocZ (Spr0334), a newly identified cell division protein, is involved in proper septum placement in Streptococcus pneumoniae. We show that locZ is not essential but that its deletion results in cell division defects and shape deformation, causing cells to divide asymmetrically and generate unequally sized, occasionally anucleated, daughter cells. LocZ has a unique localization profile. It arrives early at midcell, before FtsZ and FtsA, and leaves the septum early, apparently moving along with the equatorial rings that mark the future division sites. Consistently, cells lacking LocZ also show misplacement of the Z-ring, suggesting that it could act as a positive regulator to determine septum placement. LocZ was identified as a substrate of the Ser/Thr protein kinase StkP, which regulates cell division in S. pneumoniae. Interestingly, homologues of LocZ are found only in streptococci, lactococci, and enterococci, indicating that this close phylogenetically related group of bacteria evolved a specific solution to spatially regulate cell division. PMID:25550321

  18. Dielectric modelling of cell division for budding and fission yeast

    International Nuclear Information System (INIS)

    Asami, Koji; Sekine, Katsuhisa

    2007-01-01

    The frequency dependence of complex permittivity or the dielectric spectrum of a system including a cell in cell division has been simulated by a numerical technique based on the three-dimensional finite difference method. Two different types of cell division characteristic of budding and fission yeast were examined. The yeast cells are both regarded as a body of rotation, and thus have anisotropic polarization, i.e. the effective permittivity of the cell depends on the orientation of the cell to the direction of an applied electric field. In the perpendicular orientation, where the rotational axis of the cell is perpendicular to the electric field direction, the dielectric spectra for both yeast cells included one dielectric relaxation and its intensity depended on the cell volume. In the parallel orientation, on the other hand, two dielectric relaxations appeared with bud growth for budding yeast and with septum formation for fission yeast. The low-frequency relaxation was shifted to a lower frequency region by narrowing the neck between the bud and the mother cell for budding yeast and by increasing the degree of septum formation for fission yeast. After cell separation, the low-frequency relaxation disappeared. The simulations well interpreted the oscillation of the relative permittivity of culture broth found for synchronous cell growth of budding yeast

  19. Regulation of the number of cell division rounds by tissue-specific transcription factors and Cdk inhibitor during ascidian embryogenesis.

    Directory of Open Access Journals (Sweden)

    Mami Kuwajima

    Full Text Available Mechanisms that regulate the number of cell division rounds during embryogenesis have remained largely elusive. To investigate this issue, we used the ascidian, which develops into a tadpole larva with a small number of cells. The embryonic cells divide 11.45 times on average from fertilization to hatching. The number of cell division rounds varies depending on embryonic lineages. Notochord and muscle consist of large postmitotic cells and stop dividing early in developing embryos. Here we show that conversion of mesenchyme to muscle cell fates by inhibition of inductive FGF signaling or mis-expression of a muscle-specific key transcription factor for muscle differentiation, Tbx6, changed the number of cell divisions in accordance with the altered fate. Tbx6 likely activates a putative mechanism to halt cell division at a specific stage. However, precocious expression of Tbx6 has no effect on progression of the developmental clock itself. Zygotic expression of a cyclin-dependent kinase inhibitor, CKI-b, is initiated in muscle and then in notochord precursors. CKI-b is possibly downstream of tissue-specific key transcription factors of notochord and muscle. In the two distinct muscle lineages, postmitotic muscle cells are generated after 9 and 8 rounds of cell division depending on lineage, but the final cell divisions occur at a similar developmental stage. CKI-b gene expression starts simultaneously in both muscle lineages at the 110-cell stage, suggesting that CKI-b protein accumulation halts cell division at a similar stage. The difference in the number of cell divisions would be due to the cumulative difference in cell cycle length. These results suggest that muscle cells do not count the number of cell division rounds, and that accumulation of CKI-b protein triggered by tissue-specific key transcription factors after cell fate determination might act as a kind of timer that measures elapsed time before cell division termination.

  20. Control of cell division and the spatial localization of assembled gene products in Caulobacter crescentus

    International Nuclear Information System (INIS)

    Nathan, P.D.

    1988-01-01

    Experiments are described that examine the role of penicillin-binding proteins (PBPs) in the regulation of cell division in Caulobacter crescentus; and the spatial localization of methyl-accepting chemotaxis proteins (MCPs) in C. crescentus swarmer and predivisional cells. In the analysis of PBP function, in vivo and in vitro assays are used to directly label C. crescentus PBPs with [ 3 H] penicillin G in wild type strain CB15, in a series of conditional cell division mutants and in new temperature sensitive cephalosporin C resistant mutants PC8002 and PC8003. 14 PBPs are characterized and a high molecular weight PBP (PBP 1B) that is required for cell division is identified. PBP 1B competes for β-lactams that induce filament formation and may be a high affinity binding protein. A second high molecular weight PBP (PBP 1C) is also associated with defective cell division. The examination of PBP patterns in synchronous swarmer cells reveals that the in vivo activity of PBP 1B and PBP 1C increases at the time that the cell division pathway is initiated. None of the PBPs, however, appear to be differentially localized in the C. crescentus cell. In the analysis of MCP localization, in vivo and in vitro assays are used to directly label C. crescentus MCPs with methyl- 3 H. MCPs are examined in flagellated and non-flagellated vesicles prepared from cells by immunoaffinity chromatography

  1. Cellular Clocks : Coupled Circadian Dispatch and Cell Division Cycles

    NARCIS (Netherlands)

    Merrow, Martha; Roenneberg, Till

    2004-01-01

    Gating of cell division by the circadian clock is well known, yet its mechanism is little understood. Genetically tractable model systems have led to new hypotheses and questions concerning the coupling of these two cellular cycles.

  2. An Improved Model of Nonuniform Coleochaete Cell Division.

    Science.gov (United States)

    Wang, Yuandi; Cong, Jinyu

    2016-08-01

    Cell division is a key biological process in which cells divide forming new daughter cells. In the present study, we investigate continuously how a Coleochaete cell divides by introducing a modified differential equation model in parametric equation form. We discuss both the influence of "dead" cells and the effects of various end-points on the formation of the new cells' boundaries. We find that the boundary condition on the free end-point is different from that on the fixed end-point; the former has a direction perpendicular to the surface. It is also shown that the outer boundaries of new cells are arc-shaped. The numerical experiments and theoretical analyses for this model to construct the outer boundary are given.

  3. Effect of anolyte on growth and division of Chinese hamster cancerous cells

    Directory of Open Access Journals (Sweden)

    saeed Mohammadzadeh

    2009-04-01

    Full Text Available Background: At present, cancer can be controlled by chemotherapy, but unfortunately, this method has strong side effects and scientist try to reduce them using different substances. 2 kinds of activated water called anolyte and catholyte have electrochemical property and antibacterial and oxidative properties respectively. The aim of this research is to study the effect of anolyte on growth and division of cancerous cells. Materials and Methods: In this research, different concentration of anolyte, 1 . 7, 2, 5,8.3 and 10 percent of anolyte and control with 2 and 5 percent of serum physiologic were added on converted cell of Chinese hamster (line b11dii-FAF28 clone 237 in 12 plastic and 15 glass flasks. After adding, converted cell was counted with the help of hoemocytometer and microscope. Data of experiment analyzed and results compared by t test, as well as using Excell software their diagrams were drawn. Results: The results indicated that anolyte had significant effect on cancer cells. In concentration of 1.7% cell division was decreased but in concentration of 8.3 %, division of cancerous cells was blocked and cells were fixed. Conclusion: Considering the low amount of sodium chloride in anolyte, it seems that, this solution (Anolyte hasn’t side effects and advers effect on the cells body.

  4. The simulation model of growth and cell divisions for the root apex with an apical cell in application to Azolla pinnata.

    Science.gov (United States)

    Piekarska-Stachowiak, Anna; Nakielski, Jerzy

    2013-12-01

    In contrast to seed plants, the roots of most ferns have a single apical cell which is the ultimate source of all cells in the root. The apical cell has a tetrahedral shape and divides asymmetrically. The root cap derives from the distal division face, while merophytes derived from three proximal division faces contribute to the root proper. The merophytes are produced sequentially forming three sectors along a helix around the root axis. During development, they divide and differentiate in a predictable pattern. Such growth causes cell pattern of the root apex to be remarkably regular and self-perpetuating. The nature of this regularity remains unknown. This paper shows the 2D simulation model for growth of the root apex with the apical cell in application to Azolla pinnata. The field of growth rates of the organ, prescribed by the model, is of a tensor type (symplastic growth) and cells divide taking principal growth directions into account. The simulations show how the cell pattern in a longitudinal section of the apex develops in time. The virtual root apex grows realistically and its cell pattern is similar to that observed in anatomical sections. The simulations indicate that the cell pattern regularity results from cell divisions which are oriented with respect to principal growth directions. Such divisions are essential for maintenance of peri-anticlinal arrangement of cell walls and coordinated growth of merophytes during the development. The highly specific division program that takes place in merophytes prior to differentiation seems to be regulated at the cellular level.

  5. Control of sporulation-specific cell division in Streptomyces coelicolor

    NARCIS (Netherlands)

    Noens, Elke

    2007-01-01

    During developmental cell division in sporulation-committed aerial hyphae of streptomycetes, up to a hundred septa are simultaneously produced, in close harmony with synchromous chromosome condensation and segregation. Several unique protein families are involved in the control of this process,

  6. Model-Based Analysis of Arabidopsis Leaf Epidermal Cells Reveals Distinct Division and Expansion Patterns for Pavement and Guard Cells1[W][OA

    Science.gov (United States)

    Asl, Leila Kheibarshekan; Dhondt, Stijn; Boudolf, Véronique; Beemster, Gerrit T.S.; Beeckman, Tom; Inzé, Dirk; Govaerts, Willy; De Veylder, Lieven

    2011-01-01

    To efficiently capture sunlight for photosynthesis, leaves typically develop into a flat and thin structure. This development is driven by cell division and expansion, but the individual contribution of these processes is currently unknown, mainly because of the experimental difficulties to disentangle them in a developing organ, due to their tight interconnection. To circumvent this problem, we built a mathematic model that describes the possible division patterns and expansion rates for individual epidermal cells. This model was used to fit experimental data on cell numbers and sizes obtained over time intervals of 1 d throughout the development of the first leaf pair of Arabidopsis (Arabidopsis thaliana). The parameters were obtained by a derivative-free optimization method that minimizes the differences between the predicted and experimentally observed cell size distributions. The model allowed us to calculate probabilities for a cell to divide into guard or pavement cells, the maximum size at which it can divide, and its average cell division and expansion rates at each point during the leaf developmental process. Surprisingly, average cell cycle duration remained constant throughout leaf development, whereas no evidence for a maximum cell size threshold for cell division of pavement cells was found. Furthermore, the model predicted that neighboring cells of different sizes within the epidermis expand at distinctly different relative rates, which could be verified by direct observations. We conclude that cell division seems to occur independently from the status of cell expansion, whereas the cell cycle might act as a timer rather than as a size-regulated machinery. PMID:21693673

  7. Cell growth and division cycle

    International Nuclear Information System (INIS)

    Darzynkiewicz, Z.

    1986-01-01

    The concept of the cell cycle in its present form was introduced more than three decades ago. Studying incorporation of DNA precursors by autoradiography, these authors observed that DNA synthesis in individual cells was discontinuous and occupied a discrete portion of the cell life (S phase). Mitotic division was seen to occur after a certain period of time following DNA replication. A distinct time interval between mitosis and DNA replication was also apparent. Thus, the cell cycle was subdivided into four consecutive phases, G/sub 1/, S, G/sub 2/, and M. The G/sub 1/ and G/sub 2/ phases represented the ''gaps'' between mitosis and the start of DNA replication, and between the end of DNA replication and the onset of mitosis, respectively. The cell cycle was defined as the interval between the midpoint of mitosis and the midpoint of the subsequent mitosis of the daughter cell(s). The authors' present knowledge on the cell cycle benefited mostly from the development of four different techniques: autoradiography, time-lapse cinematography, cell synchronization and flow cytometry. Of these, autoradiography has been the most extensively used, especially during the past two decades. By providing a means to analyse incorporation of precursors of DNA, RNA or proteins by individual cells and, in combination with various techniques of cell synchronization, autoradiography yielded most of the data fundamental to the current understanding of the cell cycle-related phenomena. Kinetics of cell progression through the cell cycle could be analysed in great detail after development of such sophisticated autoradiographic approaches as measurements of the fraction of labeled mitoses (''FLM curves'') or multiple sequential cell labelling with /sup 3/H- and /sup 14/C-TdR

  8. Chlamydia co-opts the rod shape-determining proteins MreB and Pbp2 for cell division.

    Science.gov (United States)

    Ouellette, Scot P; Karimova, Gouzel; Subtil, Agathe; Ladant, Daniel

    2012-07-01

    Chlamydiae are obligate intracellular bacterial pathogens that have extensively reduced their genome in adapting to the intracellular environment. The chlamydial genome contains only three annotated cell division genes and lacks ftsZ. How this obligate intracellular pathogen divides is uncharacterized. Chlamydiae contain two high-molecular-weight (HMW) penicillin binding proteins (Pbp) implicated in peptidoglycan synthesis, Pbp2 and Pbp3/FtsI. We show here, using HMW Pbp-specific penicillin derivatives, that both Pbp2 and Pbp3 are essential for chlamydial cell division. Ultrastructural analyses of antibiotic-treated cultures revealed distinct phenotypes: Pbp2 inhibition induced internal cell bodies within a single outer membrane whereas Pbp3 inhibition induced elongated phenotypes with little internal division. Each HMW Pbp interacts with the Chlamydia cell division protein FtsK. Chlamydiae are coccoid yet contain MreB, a rod shape-determining protein linked to Pbp2 in bacilli. Using MreB-specific antibiotics, we show that MreB is essential for chlamydial growth and division. Importantly, co-treatment with MreB-specific and Pbp-specific antibiotics resulted in the MreB-inhibited phenotype, placing MreB upstream of Pbp function in chlamydial cell division. Finally, we showed that MreB also interacts with FtsK. We propose that, in Chlamydia, MreB acts as a central co-ordinator at the division site to substitute for the lack of FtsZ in this bacterium. © 2012 Blackwell Publishing Ltd.

  9. Investigation of roles for LRR-RLKs PNL1 and PNL2 in asymmetric cell division in Arabidopsis thaliana

    OpenAIRE

    Rodriguez, Maiti Celina

    2008-01-01

    Asymmetric cell division is a vital component of plant development. It enables cell differentiation and cell diversity. A key component of asymmetric cell division is cell signaling. Signals are believed to control polarization and orientation of asymmetric divisions during stomatal development. The findings of this report suggest that PNL1 and PNL2, two LRR-RLKs found in Arabidopsis and closely related to maize PAN1 LRR-RLK, are possibly involved in the signaling events occurring during the ...

  10. The deletion of bacterial dynamin and flotillin genes results in pleiotrophic effects on cell division, cell growth and in cell shape maintenance

    Directory of Open Access Journals (Sweden)

    Dempwolff Felix

    2012-12-01

    Full Text Available Abstract Background In eukaryotic cells, dynamin and flotillin are involved in processes such as endocytosis and lipid raft formation, respectively. Dynamin is a GTPase that exerts motor-like activity during the pinching off of vesicles, while flotillins are coiled coil rich membrane proteins with no known enzymatic activity. Bacteria also possess orthologs of both classes of proteins, but their function has been unclear. Results We show that deletion of the single dynA or floT genes lead to no phenotype or a mild defect in septum formation in the case of the dynA gene, while dynA floT double mutant cells were highly elongated and irregularly shaped, although the MreB cytoskeleton appeared to be normal. DynA colocalizes with FtsZ, and the dynA deletion strain shows aberrant FtsZ rings in a subpopulation of cells. The mild division defect of the dynA deletion is exacerbated by an additional deletion in ezrA, which affects FtsZ ring formation, and also by the deletion of a late division gene (divIB, indicating that DynA affects several steps in cell division. DynA and mreB deletions generated a synthetic defect in cell shape maintenance, showing that MreB and DynA play non-epistatic functions in cell shape maintenance. TIRF microscopy revealed that FloT forms many dynamic membrane assemblies that frequently colocalize with the division septum. The deletion of dynA did not change the pattern of localization of FloT, and vice versa, showing that the two proteins play non redundant roles in a variety of cellular processes. Expression of dynamin or flotillin T in eukaryotic S2 cells revealed that both proteins assemble at the cell membrane. While FloT formed patch structures, DynA built up tubulated structures extending away from the cells. Conclusions Bacillus subtilis dynamin ortholog DynA plays a role during cell division and in cell shape maintenance. It shows a genetic link with flotillin T, with both proteins playing non-redundant functions at

  11. Effect of gamma-irradiation and colchicine on cell division and differentiation of xylem elements in citrus limon juice vesicle cultures

    International Nuclear Information System (INIS)

    Khan, Aysha; Chauhan, Y.S.

    1999-01-01

    The effects of varying doses of gamma irradiation on cell division and cytodifferentiation of tracheary elements in cultured juice vesicles of Citrus limon (L) Burmann var. Assam lemon were investigated. Low radiation doses stimulated cell division and differentiation of xylem fibres, sclereids and tracheids in explants given up to 10 Gy of gamma rays. Although cell division and cytodifferentiation of fibers and sclereids occurred in explants exposed to 150 dose of Gy radiation, the intensity of differentiation was much less than that induced by 10 Gy radiation dose. Amongst the differential elements, tracheids were more sensitive to radiation than fibres and sclereids. The requirement of cell division for differentiation of xylem cells was also studied by using different concentrations of colchicine in Citrus limon juice vesicle cultures. It was found that the low concentrations of colchicine permitted normal cell division and also resulted in normal differentiation of xylem cells; higher colchicine concentration, however, inhibited cell division as well as differentiation and resulted in an abnormal differentiation of tracheary element. A positive correlation between intensity of nucleic acid staining and cell division in both the above-mentioned experiments was qualitatively confirmed by Azur B staining test of nucleic acid. Thus, it was concluded that juice vesicle parenchyma cells go through nucleic acid synthesis, followed by cell division before differentiation. (author)

  12. 2003 Chemical Engineering Division annual technical report

    International Nuclear Information System (INIS)

    Lewis, D.; Graziano, D.; Miller, J. F.; Vandegrift, G.

    2004-01-01

    national importance. Included among them are: Advanced lithium-ion and lithium-polymer batteries for transportation and other applications, Fuel cells, including the use of an oxidative reformer with gasoline as the fuel supply, Production and storage technologies critical to the hydrogen economy, Stable nuclear waste forms suitable for storage in a geological repository, Threat attribution and training relative to radioactive dispersal devices (''dirty bombs''), and Aqueous and pyrochemical processes for the disposition of spent nuclear fuel. Other important programs are focused in superconductivity, catalysis, nanotechnology, and nuclear materials. During fiscal year 2003, CMT had an annual operating budget of approximately $36 million. Of that, more than 90% was from DOE and the remainder from other government agencies and private industry. Displayed below is an overview organization chart of the Division. A complete organization chart appears at the end of this report. In this annual report we present an overview of the technical programs together with representative highlights. The report is not intended to be comprehensive or encyclopedic, but to serve as an indication of the condition and status of the Division

  13. Microgravity effects during fertilization, cell division, development, and calcium metabolism in sea urchins

    Science.gov (United States)

    Schatten, Heide

    1996-01-01

    The overall objectives of this project are to explore the role of microgravity during fertilization, early development, cytoskeletal organization, and skeletal calcium deposition in a model development system: the sea urchin eggs and embryos. While pursuing these objectives, we have also helped to develop, test, and fly the Aquatic Research Facility (ARF) system. Cells were fixed at preselected time points to preserve the structures and organelles of interest with regards to cell biology events during development. The protocols used for the analysis of the results had been developed during the earlier part of this research and were applied for post-flight analysis using light and (immuno)fluorescence microscopy, scanning electron microscopy, and transmission electron microscopy. The structures of interest are: microtubules during fertilization, cell division, and cilia movement; microfilaments during cell surface restructuring and cell division; centrosomes and centrioles during cell division, cell differentiation, and cilia formation and movement; membranes, Golgi, endoplasmic reticulum, mitochondria, and chromosomes at all stages of development; and calcium deposits during spicule formation in late-stage embryos. In addition to further explore aspects important or living in space, several aspects of this research are also aimed at understanding diseases that affect humans on Earth which may be accelerated in space.

  14. Cell Division, a new open access online forum for and from the cell cycle community

    Directory of Open Access Journals (Sweden)

    Kaldis Philipp

    2006-04-01

    Full Text Available Abstract Cell Division is a new, open access, peer-reviewed online journal that publishes cutting-edge articles, commentaries and reviews on all exciting aspects of cell cycle control in eukaryotes. A major goal of this new journal is to publish timely and significant studies on the aberrations of the cell cycle network that occur in cancer and other diseases.

  15. A millifluidic study of cell-to-cell heterogeneity in growth-rate and cell-division capability in populations of isogenic cells of Chlamydomonas reinhardtii.

    Directory of Open Access Journals (Sweden)

    Shima P Damodaran

    Full Text Available To address possible cell-to-cell heterogeneity in growth dynamics of isogenic cell populations of Chlamydomonas reinhardtii, we developed a millifluidic drop-based device that not only allows the analysis of populations grown from single cells over periods of a week, but is also able to sort and collect drops of interest, containing viable and healthy cells, which can be used for further experimentation. In this study, we used isogenic algal cells that were first synchronized in mixotrophic growth conditions. We show that these synchronized cells, when placed in droplets and kept in mixotrophic growth conditions, exhibit mostly homogeneous growth statistics, but with two distinct subpopulations: a major population with a short doubling-time (fast-growers and a significant subpopulation of slowly dividing cells (slow-growers. These observations suggest that algal cells from an isogenic population may be present in either of two states, a state of restricted division and a state of active division. When isogenic cells were allowed to propagate for about 1000 generations on solid agar plates, they displayed an increased heterogeneity in their growth dynamics. Although we could still identify the original populations of slow- and fast-growers, drops inoculated with a single progenitor cell now displayed a wider diversity of doubling-times. Moreover, populations dividing with the same growth-rate often reached different cell numbers in stationary phase, suggesting that the progenitor cells differed in the number of cell divisions they could undertake. We discuss possible explanations for these cell-to-cell heterogeneities in growth dynamics, such as mutations, differential aging or stochastic variations in metabolites and macromolecules yielding molecular switches, in the light of single-cell heterogeneities that have been reported among isogenic populations of other eu- and prokaryotes.

  16. Xanthomonas citri MinC Oscillates from Pole to Pole to Ensure Proper Cell Division and Shape

    NARCIS (Netherlands)

    Soibelmann Glock Lorenzoni, André; Dantas, Giordanni; Bergsma, Tessa; Ferreira, Henrique; Scheffers, Dirk

    2017-01-01

    Xanthomonas citri (Xac) is the causal agent of citrus canker, a disease that affects citrus crops and causes economic impact worldwide. To further characterize cell division in this plant pathogen, we investigated the role of the protein MinC in cell division, chromosome segregation, and

  17. Inhibition of cell division in hupA hupB mutant bacteria lacking HU protein.

    OpenAIRE

    Dri, A M; Rouviere-Yaniv, J; Moreau, P L

    1991-01-01

    Escherichia coli hupA hypB double mutants that lack HU protein have severe cellular defects in cell division, DNA folding, and DNA partitioning. Here we show that the sfiA11 mutation, which alters the SfiA cell division inhibitor, reduces filamentation and production of anucleate cells in AB1157 hupA hupB strains. However, lexA3(Ind-) and sfiB(ftsZ)114 mutations, which normally counteract the effect of the SfiA inhibitor, could not restore a normal morphology to hupA hupB mutant bacteria. The...

  18. Tetracycline hypersensitivity of an ezrA mutant links GalE and TseB (YpmB to cell division

    Directory of Open Access Journals (Sweden)

    Pamela eGamba

    2015-04-01

    Full Text Available Cell division in bacteria is initiated by the polymerization of FtsZ into a ring-like structure at midcell that functions as a scaffold for the other cell division proteins. In Bacillus subtilis, the conserved cell division protein EzrA is involved in modulation of Z-ring formation and coordination of septal peptidoglycan synthesis. Here, we show that an ezrA mutant is hypersensitive to tetracycline, even when the tetracycline efflux pump TetA is present. This effect is not related to the protein translation inhibiting activity of tetracycline. Overexpression of FtsL suppresses this phenotype, which appears to be related to the intrinsic low FtsL levels in an ezrA mutant background. A transposon screen indicated that the tetracycline effect can also be suppressed by overproduction of the cell division protein ZapA. In addition, tetracycline sensitivity could be suppressed by transposon insertions in galE and the unknown gene ypmB, which was renamed tseB (tetracycline sensitivity suppressor of ezrA. GalE is an epimerase using UDP-glucose and UDP-N-acetylglucosamine as substrate. Deletion of this protein bypasses the synthetic lethality of zapA ezrA and sepF ezrA double mutations, indicating that GalE influences cell division. The transmembrane protein TseB contains an extracytoplasmic peptidase domain, and a GFP fusion shows that the protein is enriched at cell division sites. A tseB deletion causes a shorter cell phenotype, indicating that TseB plays a role in cell division. Why a deletion of ezrA renders B. subtilis cells hypersensitive for tetracycline remains unclear. We speculate that this phenomenon is related to the tendency of tetracycline analogues to accumulate into the lipid bilayer, which may destabilize certain membrane proteins.

  19. Uhrf1 controls the self-renewal versus differentiation of hematopoietic stem cells by epigenetically regulating the cell-division modes.

    Science.gov (United States)

    Zhao, Jingyao; Chen, Xufeng; Song, Guangrong; Zhang, Jiali; Liu, Haifeng; Liu, Xiaolong

    2017-01-10

    Hematopoietic stem cells (HSCs) are able to both self-renew and differentiate. However, how individual HSC makes the decision between self-renewal and differentiation remains largely unknown. Here we report that ablation of the key epigenetic regulator Uhrf1 in the hematopoietic system depletes the HSC pool, leading to hematopoietic failure and lethality. Uhrf1-deficient HSCs display normal survival and proliferation, yet undergo erythroid-biased differentiation at the expense of self-renewal capacity. Notably, Uhrf1 is required for the establishment of DNA methylation patterns of erythroid-specific genes during HSC division. The expression of these genes is enhanced in the absence of Uhrf1, which disrupts the HSC-division modes by promoting the symmetric differentiation and suppressing the symmetric self-renewal. Moreover, overexpression of one of the up-regulated genes, Gata1, in HSCs is sufficient to phenocopy Uhrf1-deficient HSCs, which show impaired HSC symmetric self-renewal and increased differentiation commitment. Taken together, our findings suggest that Uhrf1 controls the self-renewal versus differentiation of HSC through epigenetically regulating the cell-division modes, thus providing unique insights into the relationship among Uhrf1-mediated DNA methylation, cell-division mode, and HSC fate decision.

  20. The TCP4 transcription factor of Arabidopsis blocks cell division in yeast at G1 → S transition

    International Nuclear Information System (INIS)

    Aggarwal, Pooja; Padmanabhan, Bhavna; Bhat, Abhay; Sarvepalli, Kavitha; Sadhale, Parag P.; Nath, Utpal

    2011-01-01

    Highlights: → TCP4 is a class II TCP transcription factor, that represses cell division in Arabidopsis. → TCP4 expression in yeast retards cell division by blocking G1 → S transition. → Genome-wide expression studies and Western analysis reveals stabilization of cell cycle inhibitor Sic1, as possible mechanism. -- Abstract: The TCP transcription factors control important aspects of plant development. Members of class I TCP proteins promote cell cycle by regulating genes directly involved in cell proliferation. In contrast, members of class II TCP proteins repress cell division. While it has been postulated that class II proteins induce differentiation signal, their exact role on cell cycle has not been studied. Here, we report that TCP4, a class II TCP protein from Arabidopsis that repress cell proliferation in developing leaves, inhibits cell division by blocking G1 → S transition in budding yeast. Cells expressing TCP4 protein with increased transcriptional activity fail to progress beyond G1 phase. By analyzing global transcriptional status of these cells, we show that expression of a number of cell cycle genes is altered. The possible mechanism of G1 → S arrest is discussed.

  1. Fibroblasts Cultured on Nanowires Exhibit Low Motility, Impaired Cell Division, and DNA Damage

    DEFF Research Database (Denmark)

    Persson, H.; Købler, Carsten; Mølhave, Kristian

    2013-01-01

    Mouse fibroblasts cultured on 7-μm-long vertical nanowires are reported on page 4006 by C. N. Prinz and co-workers. Culturing cells on this kind of substrate interferes greatly with cell function, causing the cells to develop into widely different morphologies. The cells' division is impaired...

  2. LexA Binds to Transcription Regulatory Site of Cell Division Gene ftsZ in Toxic Cyanobacterium Microcystis aeruginosa.

    Science.gov (United States)

    Honda, Takashi; Morimoto, Daichi; Sako, Yoshihiko; Yoshida, Takashi

    2018-05-17

    Previously, we showed that DNA replication and cell division in toxic cyanobacterium Microcystis aeruginosa are coordinated by transcriptional regulation of cell division gene ftsZ and that an unknown protein specifically bound upstream of ftsZ (BpFz; DNA-binding protein to an upstream site of ftsZ) during successful DNA replication and cell division. Here, we purified BpFz from M. aeruginosa strain NIES-298 using DNA-affinity chromatography and gel-slicing combined with gel electrophoresis mobility shift assay (EMSA). The N-terminal amino acid sequence of BpFz was identified as TNLESLTQ, which was identical to that of transcription repressor LexA from NIES-843. EMSA analysis using mutant probes showed that the sequence GTACTAN 3 GTGTTC was important in LexA binding. Comparison of the upstream regions of lexA in the genomes of closely related cyanobacteria suggested that the sequence TASTRNNNNTGTWC could be a putative LexA recognition sequence (LexA box). Searches for TASTRNNNNTGTWC as a transcriptional regulatory site (TRS) in the genome of M. aeruginosa NIES-843 showed that it was present in genes involved in cell division, photosynthesis, and extracellular polysaccharide biosynthesis. Considering that BpFz binds to the TRS of ftsZ during normal cell division, LexA may function as a transcriptional activator of genes related to cell reproduction in M. aeruginosa, including ftsZ. This may be an example of informality in the control of bacterial cell division.

  3. Individuality and universality in the growth-division laws of single E. coli cells

    Science.gov (United States)

    Kennard, Andrew S.; Osella, Matteo; Javer, Avelino; Grilli, Jacopo; Nghe, Philippe; Tans, Sander J.; Cicuta, Pietro; Cosentino Lagomarsino, Marco

    2016-01-01

    The mean size of exponentially dividing Escherichia coli cells in different nutrient conditions is known to depend on the mean growth rate only. However, the joint fluctuations relating cell size, doubling time, and individual growth rate are only starting to be characterized. Recent studies in bacteria reported a universal trend where the spread in both size and doubling times is a linear function of the population means of these variables. Here we combine experiments and theory and use scaling concepts to elucidate the constraints posed by the second observation on the division control mechanism and on the joint fluctuations of sizes and doubling times. We found that scaling relations based on the means collapse both size and doubling-time distributions across different conditions and explain how the shape of their joint fluctuations deviates from the means. Our data on these joint fluctuations highlight the importance of cell individuality: Single cells do not follow the dependence observed for the means between size and either growth rate or inverse doubling time. Our calculations show that these results emerge from a broad class of division control mechanisms requiring a certain scaling form of the "division hazard rate function," which defines the probability rate of dividing as a function of measurable parameters. This "model free" approach gives a rationale for the universal body-size distributions observed in microbial ecosystems across many microbial species, presumably dividing with multiple mechanisms. Additionally, our experiments show a crossover between fast and slow growth in the relation between individual-cell growth rate and division time, which can be understood in terms of different regimes of genome replication control.

  4. Live imaging of individual cell divisions in mouse neuroepithelium shows asymmetry in cilium formation and Sonic hedgehog response

    Directory of Open Access Journals (Sweden)

    Piotrowska-Nitsche Karolina

    2012-05-01

    Full Text Available Abstract Background Primary cilia are microtubule-based sensory organelles that play important roles in developmental signaling pathways. Recent work demonstrated that, in cell culture, the daughter cell that inherits the older mother centriole generates a primary cilium and responds to external stimuli prior to its sister cell. This asynchrony in timing of cilia formation could be especially critical during development as cell divisions are required for both differentiation and maintenance of progenitor cell niches. Methods Here we integrate several fluorescent markers and use ex vivo live imaging of a single cell division within the mouse E8.5 neuroepithelium to reveal both the formation of a primary cilium and the transcriptional response to Sonic hedgehog in the daughter cells. Results We show that, upon cell division, cilia formation and the Sonic hedgehog response are asynchronous between the daughter cells. Conclusions Our results demonstrate that we can directly observe single cell divisions within the developing neuroepithelium and concomitantly monitor cilium formation or Sonic hedgehog response. We expect this method to be especially powerful in examining whether cellular behavior can lead to both differentiation and maintenance of cells in a progenitor niche.

  5. Activation of cell divisions in legume nodulation

    DEFF Research Database (Denmark)

    Nadzieja, Marcin

    organogenesis. Coordination of these two interdependent processes results in formation of nodules - bacterial accommodating structures where fixation of atmospheric nitrogen takes place. Plant hormones such as auxin and cytokinin play important roles in nodulation. In some legumes the infection process...... of auxin transport inhibitors or cytokinin alone was shown to induce cortical cell divisions in the absence of rhizobia in certain legume species. While the roles of auxin and cytokinin in nodulation have been studied extensively, the precise timing, location and means of molecular crosstalk between...

  6. Inhibition of cell division in hupA hupB mutant bacteria lacking HU protein.

    Science.gov (United States)

    Dri, A M; Rouviere-Yaniv, J; Moreau, P L

    1991-01-01

    Escherichia coli hupA hypB double mutants that lack HU protein have severe cellular defects in cell division, DNA folding, and DNA partitioning. Here we show that the sfiA11 mutation, which alters the SfiA cell division inhibitor, reduces filamentation and production of anucleate cells in AB1157 hupA hupB strains. However, lexA3(Ind-) and sfiB(ftsZ)114 mutations, which normally counteract the effect of the SfiA inhibitor, could not restore a normal morphology to hupA hupB mutant bacteria. The LexA repressor, which controls the expression of the sfiA gene, was present in hupA hupB mutant bacteria in concentrations half of those of the parent bacteria, but this decrease was independent of the specific cleavage of the LexA repressor by activated RecA protein. One possibility to account for the filamentous morphology of hupA hupB mutant bacteria is that the lack of HU protein alters the expression of specific genes, such as lexA and fts cell division genes. Images PMID:2019558

  7. A plant U-box protein, PUB4, regulates asymmetric cell division and cell proliferation in the root meristem

    NARCIS (Netherlands)

    Kinoshita, A.; Hove, ten C.A.; Tabata, R.; Yamada, M.; Shimizu, N.; Ishida, T.; Yamaguchi, K.; Shigenobu, S.; Takebayashi, Y.; Luchies, J.; Kobayashi, M.; Kurata, T.; Wada, T.; Seo, M.; Hasebe, M.; Blilou, I.; Fukuda, H.; Scheres, B.; Heidstra, R.; Kamiya, Y.; Sawa, S.

    2015-01-01

    The root meristem (RM) is a fundamental structure that is responsible for postembryonic root growth. The RM contains the quiescent center (QC), stem cells and frequently dividing meristematic cells, in which the timing and the frequency of cell division are tightly regulated. In Arabidopsis

  8. Cell division genes promote asymmetric interaction between Numb and Notch in the Drosophila CNS.

    Science.gov (United States)

    Wai, P; Truong, B; Bhat, K M

    1999-06-01

    Cell intrinsic and cell extrinsic factors mediate asymmetric cell divisions during neurogenesis in the Drosophila embryo. In the NB4-2->GMC-1->RP2/sib lineage, one of the well-studied neuronal lineages in the ventral nerve cord, the Notch (N) signaling interacts with the asymmetrically localized Numb (Nb) to specify sibling neuronal fates to daughter cells of GMC-1. In this current study, we have investigated asymmetric cell fate specifications by N and Nb in the context of cell cycle. We have used loss-of-function mutations in N and nb, cell division mutants cyclinA (cycA), regulator of cyclin A1 (rca1) and string/cdc25 phosphatase (stg), and the microtubule destabilizing agent, nocodazole, to investigate this issue. We report that the loss of cycA, rca1 or stg leads to a block in the division of GMC-1, however, this GMC-1 exclusively adopts an RP2 identity. While the loss of N leads to the specification of RP2 fates to both progeny of GMC-1 and loss of nb results in the specification of sib fates to these daughter cells, the GMC-1 in the double mutant between nb and cycA assumes a sib fate. These epistasis results indicate that both N and nb function downstream of cell division genes and that progression through cell cycle is required for the asymmetric localization of Nb. In the absence of entry to metaphase, the Nb protein prevents the N signaling from specifying sib fate to the RP2/sib precursor. These results are also consistent with our finding that the sib cell is specified as RP2 in N; nb double mutants. Finally, our results show that nocodazole-arrested GMC-1 in wild-type embryos randomly assumes either an RP2 fate or a sib fate. This suggests that microtubules are involved in mediating the antagonistic interaction between Nb and N during RP2 and sib fate specification.

  9. Radiation effects on cultured mouse embryos in relation to cell division cycle

    International Nuclear Information System (INIS)

    Domon, M.

    1982-01-01

    The authors have worked with mouse embryos in vitro asking first, what are the suitable parameters to define the radiation sensitivity of embryos, and second what is a major factor determining it. The LD 50 was adopted as a parameter of the radiation sensitivity of a population in a mouse embryo system in culture. The fertilized ova were collected into Whitten's medium at various times during the pronuclear and 2-cell stages of development. They were irradiated in chambers with X-rays at doses of 0 to 800 rads. After the embryos were cultured, a set of the lethal fractions for various X-ray doses were obtained. Regarding the radiation sensitivity variation of the embryos, the LD 50 varied from 100 to 200 rads during the pronuclear stage and from 100 to 600 rads during the 2-cell stage. The embryos during the pronuclear stage were most radioresistant at early G 2 phase, followed by an increase in the sensitivity. The embryos during the 2-cell stage were also most radioresistant at early G 2 phase and were more sensitive when they got close to either the first or the second cleavage division. Furthermore, it seems that the factor 6 of the large variation was due to the extremely long G 2 period, 14 hrs for the 2-cell embryos. That is, the pooled 2-cell embryos were in a relative sense well synchronized with G 2 phase. In contrast, the synchrony was poor during the pronuclear stage, which led to less variation of the LD 50 for the pronuclear embryos. It is concluded that during the early cleavage stages of mice, radiosensitivity is mainly governed by the content of cells of various cell cycle ages in the embryo. (Namekawa, K.)

  10. Characterization of substances that restore impaired cell division of UV-irradiated E. coli B

    International Nuclear Information System (INIS)

    Yoshiyama, Y.; Shimoii, H.; Tamura, G.

    1981-01-01

    Substances which restore impaired cell division in UV-irradiated E. coli B were surveyed among various bacteria. The active substance was found only in several genera of Gram-negative bacteria, i.e., Escherichia, Enterobacter, Salmonella and some species of Pseudomonas. The activity in the dialyzed cell extract of E. coli B/r was observed in the presence of β-NAD and was enhanced by Mg 2+ and Mn 2+ . The active substance was very labile, but the activity was protected by 1 mM dithiothreitol in the process of purification. The activity of a fraction recovered through DEAE-cellulose column chromatography was stimulated by the presence of membrane fraction. Upon treatment with lipid-degrading enzymes and proteases, the division-stimulating activity was lost or reduced. It appears that the inactivation by lipase and phospholipase A2 was due to the formation of lysophospholipids and that a proteinous substance participated in the recovery of impaired cell division of UV-irradiated E. coli B

  11. Cell division in Escherichia coli BS-12 is hypersensitive to deoxyribonucleic acid damage by ultraviolet light

    International Nuclear Information System (INIS)

    Bridges, B.A.; Mottershead, R.P.; Green, M.H.

    1977-01-01

    Escherichia coli BS-12 uvrA lon is hypersensitive to ultraviolet light. On minimal agar plates at densities in excess of about 10(7) bacteria per plate, as few as one or two photoreversible pyrimidine dimers in the entire genome are sufficient to cause inhibition of cell division. Most of the resulting filaments are unable to divide or form a viable colony. Inhibition of cell division appears to be a rapid consequence of replication of deoxyribonucleic acid containing a pyrimidine dimer. Photoreversibility of the inhibition of cell division persists indefinitely, indicating that the continued presence of the pyrimidine dimers (or the continued generation of daughter strand gaps) is necessary to maintain the division-inhibited state. In view of the kinetics for the production of filamentation by ultraviolet light and the extremely low average inducing fluence (0.03 J/m2), it is concluded that the initiating signal is not the same as that causing other inducible phenomena such as prophage induction or Weigle reactivation

  12. The United Kingdom Atomic Energy Authority Government Division's written evidence to the Trade and Industry Committee inquiry into the Government's proposals for nuclear privatisation

    International Nuclear Information System (INIS)

    1995-01-01

    Successful privatisation of the United Kingdom nuclear industry requires the best solution for the future of nuclear liabilities associated with the decommissioning of nuclear facilities and management of the resultant radioactive wastes. At least some of these liabilities will remain in the public sector. The UKAEA Government Division was brought into being in 1994 to manage the UKAEA's nuclear liabilities. The evidence presented suggests how the experience and expertise of this organisation may be valuable in deciding how public sector nuclear liabilities in general can best be handled. In particular, a number of operating principles have been established which could be successfully applied to the management of other nuclear liabilities. (UK)

  13. An archaebacterial homologue of the essential eubacterial cell division protein FtsZ.

    Science.gov (United States)

    Baumann, P; Jackson, S P

    1996-06-25

    Life falls into three fundamental domains--Archaea, Bacteria, and Eucarya (formerly archaebacteria, eubacteria, and eukaryotes,. respectively). Though Archaea lack nuclei and share many morphological features with Bacteria, molecular analyses, principally of the transcription and translation machineries, have suggested that Archaea are more related to Eucarya than to Bacteria. Currently, little is known about the archaeal cell division apparatus. In Bacteria, a crucial component of the cell division machinery is FtsZ, a GTPase that localizes to a ring at the site of septation. Interestingly, FtsZ is distantly related in sequence to eukaryotic tubulins, which also interact with GTP and are components of the eukaryotic cell cytoskeleton. By screening for the ability to bind radiolabeled nucleotides, we have identified a protein of the hyperthermophilic archaeon Pyrococcus woesei that interacts tightly and specifically with GTP. Furthermore, through screening an expression library of P. woesei genomic DNA, we have cloned the gene encoding this protein. Sequence comparisons reveal that the P. woesei GTP-binding protein is strikingly related in sequence to eubacterial FtsZ and is marginally more similar to eukaryotic tubulins than are bacterial FtsZ proteins. Phylogenetic analyses reinforce the notion that there is an evolutionary linkage between FtsZ and tubulins. These findings suggest that the archaeal cell division apparatus may be fundamentally similar to that of Bacteria and lead us to consider the evolutionary relationships between Archaea, Bacteria, and Eucarya.

  14. Amoebiasis and its effect on cell division in the midgut of the African ...

    African Journals Online (AJOL)

    cells was noted in the nidi of the ventricular regions of locusts in- fected with parasites. ... migratoria and as these tissues undergo cell division the. R eprod u ced ..... repair or possibly could have completed DNA synthesis, divi- sion and ...

  15. Control of the proportion of inner cells by asymmetric divisions and the ensuing resilience of cloned rabbit embryos

    Science.gov (United States)

    Duranthon, Véronique

    2018-01-01

    ABSTRACT Mammalian embryo cloning by nuclear transfer has a low success rate. This is hypothesized to correlate with a high variability of early developmental steps that segregate outer cells, which are fated to extra-embryonic tissues, from inner cells, which give rise to the embryo proper. Exploring the cell lineage of wild-type embryos and clones, imaged in toto until hatching, highlights the respective contributions of cell proliferation, death and asymmetric divisions to phenotypic variability. Preferential cell death of inner cells in clones, probably pertaining to the epigenetic plasticity of the transferred nucleus, is identified as a major difference with effects on the proportion of inner cell. In wild type and clones, similar patterns of outer cell asymmetric divisions are shown to be essential to the robust proportion of inner cells observed in wild type. Asymmetric inner cell division, which is not described in mice, is identified as a regulator of the proportion of inner cells and likely gives rise to resilient clones. PMID:29567671

  16. Transmission of persistent ionizing radiation-induced foci through cell division in human primary cells

    Energy Technology Data Exchange (ETDEWEB)

    Vaurijoux, Aurelie, E-mail: aurelie.vaurijoux@irsn.fr [Institut de Radioprotection et de Sureté Nucléaire (IRSN), Laboratoire de Dosimétrie Biologique, BP 17, 92262 Fontenay aux roses cedex (France); Voisin, Pascale; Freneau, Amelie [Institut de Radioprotection et de Sureté Nucléaire (IRSN), Laboratoire de Dosimétrie Biologique, BP 17, 92262 Fontenay aux roses cedex (France); Barquinero, Joan Francesc [Universitat Autònoma de Barcelona, Faculty of Biosciences, 08193 Cerdanyola del Vallès (Spain); Gruel, Gaetan [Institut de Radioprotection et de Sureté Nucléaire (IRSN), Laboratoire de Dosimétrie Biologique, BP 17, 92262 Fontenay aux roses cedex (France)

    2017-03-15

    Highlights: • Persistent IRIF do not permanently block cell proliferation. • Persistent IRIF are transmitted in part and sometimes asymmetrically to daughter cells. • IRIF differ in their nature before and after the first cell division. - Abstract: Unrepaired DNA double-strand breaks (DSBs) induced by ionizing radiation are associated with lethal effects and genomic instability. After the initial breaks and chromatin destabilization, a set of post-translational modifications of histones occurs, including phosphorylation of serine 139 of histone H2AX (γH2AX), which leads to the formation of ionizing radiation-induced foci (IRIF). DSB repair results in the disappearance of most IRIF within hours after exposure, although some remain 24 h after irradiation. Their relation to unrepaired DSBs is generally accepted but still controversial. This study evaluates the frequency and kinetics of persistent IRIF and analyzes their impact on cell proliferation. We observed persistent IRIF up to 7 days postirradiation, and more than 70% of cells exposed to 5 Gy had at least one of these persistent IRIF 24 h after exposure. Moreover we demonstrated that persistent IRIF did not block cell proliferation definitively. The frequency of IRIF was lower in daughter cells, due to asymmetric distribution of IRIF between some of them. We report a positive association between the presence of IRIF and the likelihood of DNA missegregation. Hence, the structure formed after the passage of a persistent IRI focus across the S and G2 phases may impede the correct segregation of the affected chromosome's sister chromatids. The ensuing abnormal resolution of anaphase might therefore cause the nature of IRIF in daughter-cell nuclei to differ before and after the first cell division. The resulting atypical chromosomal assembly may be lethal or result in a gene dosage imbalance and possibly enhanced genomic instability, in particular in the daughter cells.

  17. Transmission of persistent ionizing radiation-induced foci through cell division in human primary cells

    International Nuclear Information System (INIS)

    Vaurijoux, Aurelie; Voisin, Pascale; Freneau, Amelie; Barquinero, Joan Francesc; Gruel, Gaetan

    2017-01-01

    Highlights: • Persistent IRIF do not permanently block cell proliferation. • Persistent IRIF are transmitted in part and sometimes asymmetrically to daughter cells. • IRIF differ in their nature before and after the first cell division. - Abstract: Unrepaired DNA double-strand breaks (DSBs) induced by ionizing radiation are associated with lethal effects and genomic instability. After the initial breaks and chromatin destabilization, a set of post-translational modifications of histones occurs, including phosphorylation of serine 139 of histone H2AX (γH2AX), which leads to the formation of ionizing radiation-induced foci (IRIF). DSB repair results in the disappearance of most IRIF within hours after exposure, although some remain 24 h after irradiation. Their relation to unrepaired DSBs is generally accepted but still controversial. This study evaluates the frequency and kinetics of persistent IRIF and analyzes their impact on cell proliferation. We observed persistent IRIF up to 7 days postirradiation, and more than 70% of cells exposed to 5 Gy had at least one of these persistent IRIF 24 h after exposure. Moreover we demonstrated that persistent IRIF did not block cell proliferation definitively. The frequency of IRIF was lower in daughter cells, due to asymmetric distribution of IRIF between some of them. We report a positive association between the presence of IRIF and the likelihood of DNA missegregation. Hence, the structure formed after the passage of a persistent IRI focus across the S and G2 phases may impede the correct segregation of the affected chromosome's sister chromatids. The ensuing abnormal resolution of anaphase might therefore cause the nature of IRIF in daughter-cell nuclei to differ before and after the first cell division. The resulting atypical chromosomal assembly may be lethal or result in a gene dosage imbalance and possibly enhanced genomic instability, in particular in the daughter cells.

  18. Plant Cell Division Analyzed by Transient Agrobacterium-Mediated Transformation of Tobacco BY-2 Cells.

    Science.gov (United States)

    Buschmann, Henrik

    2016-01-01

    The continuing analysis of plant cell division will require additional protein localization studies. This is greatly aided by GFP-technology, but plant transformation and the maintenance of transgenic lines can present a significant technical bottleneck. In this chapter I describe a method for the Agrobacterium-mediated genetic transformation of tobacco BY-2 cells. The method allows for the microscopic analysis of fluorescence-tagged proteins in dividing cells in within 2 days after starting a coculture. This transient transformation procedure requires only standard laboratory equipment. It is hoped that this rapid method would aid researchers conducting live-cell localization studies in plant mitosis and cytokinesis.

  19. Systemic control of cell division and endoreduplication by NAA and BAP by modulating CDKs in root tip cells of Allium cepa.

    Science.gov (United States)

    Tank, Jigna G; Thaker, Vrinda S

    2014-01-01

    Molecular mechanism regulated by auxin and cytokinin during endoreduplication, cell division, and elongation process is studied by using Allium cepa roots as a model system. The activity of CDK genes modulated by auxin and cytokinin during cell division, elongation, and endoreduplication process is explained in this research work. To study the significance of auxin and cytokinin in the management of cell division and endoreduplication process in plant meristematic cells at molecular level endoreduplication was developed in root tips of Allium cepa by giving colchicine treatment. There were inhibition of vegetative growth, formation of c-tumor at root tip, and development of endoreduplicated cells after colchicine treatment. This c-tumor was further treated with NAA and BAP to reinitiate vegetative growth in roots. BAP gave positive response in reinitiation of vegetative growth of roots from center of c-tumor. However, NAA gave negative response in reinitiation of vegetative growth of roots from c-tumor. Further, CDKs gene expression analysis from normal, endoreduplicated, and phytohormone (NAA or BAP) treated root tip was done and remarkable changes in transcription level of CDK genes in normal, endoreduplicated, and phytohormones treated cells were observed.

  20. EzrA: a spectrin-like scaffold in the bacterial cell division machinery

    Directory of Open Access Journals (Sweden)

    Robert M Cleverley

    2015-01-01

    Full Text Available Much progress has been made in identifying the components of the divisome, the assembly of proteins that undertakes the vital process of cell division in bacteria. However, how the highly interdependent processes on either side of the membrane are coordinated during division is a major unresolved question. How is the degradation and synthesis of the cell wall on the outside of the cell coordinated with cytokinesis and membrane fission, which are driven from the inside of the cell by the tubulin homologue FtsZ? A possible key mediator of such coordination is the membrane protein EzrA, as it interacts both with FtsZ and the penicillin binding proteins (PBPs that synthesize peptidoglycan. Cleverley et al. [Nature Communications (2014 5, 5421] have recently solved the crystal structure of the cytoplasmic domain of B. subtilis EzrA, which points to an important scaffolding role for EzrA in the divisome. The structure resembles the eukaryotic, cytoskeletal spectrin proteins, which link actin filaments in the cytoskeleton and also connect the actin cytoskeleton to membrane-bound integrin proteins.

  1. Characterization of harpy/Rca1/emi1 mutants: patterning in the absence of cell division.

    Science.gov (United States)

    Riley, Bruce B; Sweet, Elly M; Heck, Rebecca; Evans, Adrienne; McFarland, Karen N; Warga, Rachel M; Kane, Donald A

    2010-03-01

    We have characterized mutations in the early arrest gene, harpy (hrp), and show that they introduce premature stops in the coding region of early mitotic inhibitor1 (Rca1/emi1). In harpy mutants, cells stop dividing during early gastrulation. Lineage analysis confirms that there is little change in cell number after approximately cycle-14. Gross patterning occurs relatively normally, and many organ primordia are produced on time but with smaller numbers of cells. Despite the lack of cell division, some organ systems continue to increase in cell number, suggesting recruitment from surrounding areas. Analysis of bromodeoxyuridine incorporation shows that endoreduplication continues in many cells well past the first day of development, but cells cease endoreduplication once they begin to differentiate and express cell-type markers. Despite relatively normal gross patterning, harpy mutants show several defects in morphogenesis, cell migration and differentiation resulting directly or indirectly from the arrest of cell division. Copyright (c) 2010 Wiley-Liss, Inc.

  2. Pathogenic Chlamydia Lack a Classical Sacculus but Synthesize a Narrow, Mid-cell Peptidoglycan Ring, Regulated by MreB, for Cell Division.

    Science.gov (United States)

    Liechti, George; Kuru, Erkin; Packiam, Mathanraj; Hsu, Yen-Pang; Tekkam, Srinivas; Hall, Edward; Rittichier, Jonathan T; VanNieuwenhze, Michael; Brun, Yves V; Maurelli, Anthony T

    2016-05-01

    The peptidoglycan (PG) cell wall is a peptide cross-linked glycan polymer essential for bacterial division and maintenance of cell shape and hydrostatic pressure. Bacteria in the Chlamydiales were long thought to lack PG until recent advances in PG labeling technologies revealed the presence of this critical cell wall component in Chlamydia trachomatis. In this study, we utilize bio-orthogonal D-amino acid dipeptide probes combined with super-resolution microscopy to demonstrate that four pathogenic Chlamydiae species each possess a ≤ 140 nm wide PG ring limited to the division plane during the replicative phase of their developmental cycles. Assembly of this PG ring is rapid, processive, and linked to the bacterial actin-like protein, MreB. Both MreB polymerization and PG biosynthesis occur only in the intracellular form of pathogenic Chlamydia and are required for cell enlargement, division, and transition between the microbe's developmental forms. Our kinetic, molecular, and biochemical analyses suggest that the development of this limited, transient, PG ring structure is the result of pathoadaptation by Chlamydia to an intracellular niche within its vertebrate host.

  3. Pathogenic Chlamydia Lack a Classical Sacculus but Synthesize a Narrow, Mid-cell Peptidoglycan Ring, Regulated by MreB, for Cell Division.

    Directory of Open Access Journals (Sweden)

    George Liechti

    2016-05-01

    Full Text Available The peptidoglycan (PG cell wall is a peptide cross-linked glycan polymer essential for bacterial division and maintenance of cell shape and hydrostatic pressure. Bacteria in the Chlamydiales were long thought to lack PG until recent advances in PG labeling technologies revealed the presence of this critical cell wall component in Chlamydia trachomatis. In this study, we utilize bio-orthogonal D-amino acid dipeptide probes combined with super-resolution microscopy to demonstrate that four pathogenic Chlamydiae species each possess a ≤ 140 nm wide PG ring limited to the division plane during the replicative phase of their developmental cycles. Assembly of this PG ring is rapid, processive, and linked to the bacterial actin-like protein, MreB. Both MreB polymerization and PG biosynthesis occur only in the intracellular form of pathogenic Chlamydia and are required for cell enlargement, division, and transition between the microbe's developmental forms. Our kinetic, molecular, and biochemical analyses suggest that the development of this limited, transient, PG ring structure is the result of pathoadaptation by Chlamydia to an intracellular niche within its vertebrate host.

  4. Light-dependent governance of cell shape dimensions in cyanobacteria

    Directory of Open Access Journals (Sweden)

    Beronda L Montgomery

    2015-05-01

    Full Text Available The regulation of cellular dimension is important for the function and survival of cells. Cellular dimensions, such as size and shape, are regulated throughout the life cycle of bacteria and can be adapted in response to environmental changes to fine-tune cellular fitness. Cell size and shape are generally coordinated with cell growth and division. Cytoskeletal regulation of cell shape and cell wall biosynthesis and/or deposition occurs in a range of organisms. Photosynthetic organisms, such as cyanobacteria, particularly exhibit light-dependent regulation of morphogenes and generation of reactive oxygen species and other signals that can impact cellular dimensions. Environmental signals initiate adjustments of cellular dimensions, which may be vitally important for optimizing resource acquisition and utilization or for coupling the cellular dimensions with the regulation of subcellular organization to maintain optimal metabolism. Although the involvement of cytoskeletal components in the regulation of cell shape is widely accepted, the signaling factors that regulate cytoskeletal and other distinct components involved in cell shape control, particularly in response to changes in external light cues, remain to be fully elucidated. In this review, factors impacting the inter-coordination of growth and division, the relationship between the regulation of cellular dimensions and central carbon metabolism, and consideration of the effects of specific environment signals, primarily light, on cell dimensions in cyanobacteria will be discussed. Current knowledge about the molecular bases of the light-dependent regulation of cellular dimensions and cell shape in cyanobacteria will be highlighted.

  5. CbtA toxin of Escherichia coli inhibits cell division and cell elongation via direct and independent interactions with FtsZ and MreB.

    Science.gov (United States)

    Heller, Danielle M; Tavag, Mrinalini; Hochschild, Ann

    2017-09-01

    The toxin components of toxin-antitoxin modules, found in bacterial plasmids, phages, and chromosomes, typically target a single macromolecule to interfere with an essential cellular process. An apparent exception is the chromosomally encoded toxin component of the E. coli CbtA/CbeA toxin-antitoxin module, which can inhibit both cell division and cell elongation. A small protein of only 124 amino acids, CbtA, was previously proposed to interact with both FtsZ, a tubulin homolog that is essential for cell division, and MreB, an actin homolog that is essential for cell elongation. However, whether or not the toxic effects of CbtA are due to direct interactions with these predicted targets is not known. Here, we genetically separate the effects of CbtA on cell elongation and cell division, showing that CbtA interacts directly and independently with FtsZ and MreB. Using complementary genetic approaches, we identify the functionally relevant target surfaces on FtsZ and MreB, revealing that in both cases, CbtA binds to surfaces involved in essential cytoskeletal filament architecture. We show further that each interaction contributes independently to CbtA-mediated toxicity and that disruption of both interactions is required to alleviate the observed toxicity. Although several other protein modulators are known to target FtsZ, the CbtA-interacting surface we identify represents a novel inhibitory target. Our findings establish CbtA as a dual function toxin that inhibits both cell division and cell elongation via direct and independent interactions with FtsZ and MreB.

  6. The Relationship between Cell Number, Division Behavior and Developmental Potential of Cleavage Stage Human Embryos: A Time-Lapse Study.

    Directory of Open Access Journals (Sweden)

    Xiangyi Kong

    Full Text Available Day 3 cleavage embryo transfer is routine in many assisted reproductive technology centers today. Embryos are usually selected according to cell number, cell symmetry and fragmentation for transfer. Many studies have showed the relationship between cell number and embryo developmental potential. However, there is limited understanding of embryo division behavior and their association with embryo cell number and developmental potential. A retrospective and observational study was conducted to investigate how different division behaviors affect cell number and developmental potential of day 3 embryos by time-lapse imaging. Based on cell number at day 3, the embryos (from 104 IVF/intracytoplasmic sperm injection (ICSI treatment cycles, n = 799 were classified as follows: less than 5 cells (10C; n = 42. Division behavior, morphokinetic parameters and blastocyst formation rate were analyzed in 5 groups of day 3 embryos with different cell numbers. In 10C embryos increased compared to 7-8C embryos (45.8%, 33.3% vs. 11.1%, respectively. In ≥5C embryos, FR and DC significantly reduced developmental potential, whereas 10C. In NB embryos, the cell cycle elongation or shortening was the main cause for abnormally low or high cell number, respectively. After excluding embryos with abnormal division behaviors, the developmental potential, implantation rate and live birth rate of day 3 embryos increased with cell number.

  7. From centriole biogenesis to cellular function: centrioles are essential for cell division at critical developmental stages.

    Science.gov (United States)

    Rodrigues-Martins, Ana; Riparbelli, Maria; Callaini, Giuliano; Glover, David M; Bettencourt-Dias, Monica

    2008-01-01

    Centrioles are essential for the formation of cilia, flagella and centrosome organization. Abnormalities in centrosome structure and number in many cancers can be associated with aberrant cell division and genomic instability.(1,2) Canonical centriole duplication occurs in coordination with the cell division cycle, such that a single new "daughter" centriole arises next to each "mother" centriole. If destroyed, or eliminated during development, centrioles can form de novo.(3-5) Here we discuss our recent data demonstrating a molecular pathway that operates in both de novo and canonical centriole biogenesis involving SAK/PLK4, SAS-6 and SAS-4.(6) We showed that centriole biogenesis is a self-assembly process locally triggered by high SAK/PLK4 activity that may or not be associated with an existing centriole. SAS-6 acts downstream of SAK/PLK4 to organize nine precentriolar units, which we call here enatosomes, fitting together laterally and longitudinally, specifying a tube-like centriole precursor.(7,8) The identification of mutants impaired in centriole biogenesis has permitted the study of the physiological consequences of their absence in the whole organism. In Drosophila, centrioles are not necessary for somatic cell divisions.(9,10) However, we show here that mitotic abnormalities arise in syncytial SAK/PLK4-derived mutant embryos resulting in lethality. Moreover male meiosis fails in both SAK/PLK4 and DSAS-4 mutant spermatids that have no centrioles. These results show diversity in the need for centrioles in cell division. This suggests that tissue specific constraints selected for different contributions of centrosome-independent and dependent mechanisms in spindle function. This heterogeneity should be taken into account both in reaching an understanding of spindle function and when designing drugs that target cell division.

  8. An archaebacterial homologue of the essential eubacterial cell division protein FtsZ.

    OpenAIRE

    Baumann, P; Jackson, S P

    1996-01-01

    Life falls into three fundamental domains--Archaea, Bacteria, and Eucarya (formerly archaebacteria, eubacteria, and eukaryotes,. respectively). Though Archaea lack nuclei and share many morphological features with Bacteria, molecular analyses, principally of the transcription and translation machineries, have suggested that Archaea are more related to Eucarya than to Bacteria. Currently, little is known about the archaeal cell division apparatus. In Bacteria, a crucial component of the cell d...

  9. Attempt to stimulate cell division in Saccharomyces cerevisiae with weak ultraviolet light

    International Nuclear Information System (INIS)

    Quickenden, T.I.; Matich, A.J.; Pung, S.H.; Tilbury, R.N.

    1989-01-01

    Liquid cultures of the yeast Saccharomyces cerevisiae were irradiated with weak light having irradiances ranging from ca. 1 X 10(2) to 5 X 10(9) photons cm-2 s-1 and at wavelengths ranging from 200 to 700 nm. When particular care was taken to control the temperature of the cultures and the flow rate of oxygen, no evidence was obtained for stimulation of either yeast growth or division by the incident light. These results do not support the claims of early workers that very low intensity uv light can stimulate cell division in living organisms

  10. Dido3 PHD Modulates Cell Differentiation and Division

    Directory of Open Access Journals (Sweden)

    Jovylyn Gatchalian

    2013-07-01

    Full Text Available Death Inducer Obliterator 3 (Dido3 is implicated in the maintenance of stem cell genomic stability and tumorigenesis. Here, we show that Dido3 regulates the expression of stemness genes in embryonic stem cells through its plant homeodomain (PHD finger. Binding of Dido3 PHD to histone H3K4me3 is disrupted by threonine phosphorylation that triggers Dido3 translocation from chromatin to the mitotic spindle. The crystal structure of Dido3 PHD in complex with H3K4me3 reveals an atypical aromatic-cage-like binding site that contains a histidine residue. Biochemical, structural, and mutational analyses of the binding mechanism identified the determinants of specificity and affinity and explained the inability of homologous PHF3 to bind H3K4me3. Together, our findings reveal a link between the transcriptional control in embryonic development and regulation of cell division.

  11. Patterns of oriented cell division during the steady-state morphogenesis of the body column in hydra.

    Science.gov (United States)

    Shimizu, H; Bode, P M; Bode, H R

    1995-12-01

    In an adult hydra, the tissue of the body column is in a dynamic state. The epithelial cells of both layers are constantly in the mitotic cycle. As the tissue expands, it is continuously displaced along the body axis in either an apical or basal direction, but not in a circumferential direction. Using a modified whole mount method we examined the orientation of mitotic spindles to determine what role the direction of cell division plays in axial displacement. Surprisingly, the direction of cell division was found to differ in the two epithelial layers. In the ectoderm it was somewhat biased in an axial direction. In the endoderm it was strongly biased in a circumferential direction. For both layers, the directional biases occurred throughout the length of the body column, with some regional variation in its extent. As buds developed into adults, the bias in each layer increased from an almost random distribution to the distinctly different orientations of the adult. Thus, to maintain the observed axial direction of tissue displacement, rearrangement of the epithelial cells of both layers must occur continuously in the adult as well as in developing animals. How the locomotory and contractile behavior of the muscle processes of the epithelial cells may effect changes in cell shape, and thereby influence the direction of cell division in each layer, is discussed.

  12. Characterization of a null allelic mutant of the rice NAL1 gene reveals its role in regulating cell division.

    Directory of Open Access Journals (Sweden)

    Dan Jiang

    Full Text Available Leaf morphology is closely associated with cell division. In rice, mutations in Narrow leaf 1 (NAL1 show narrow leaf phenotypes. Previous studies have shown that NAL1 plays a role in regulating vein patterning and increasing grain yield in indica cultivars, but its role in leaf growth and development remains unknown. In this report, we characterized two allelic mutants of NARROW LEAF1 (NAL1, nal1-2 and nal1-3, both of which showed a 50% reduction in leaf width and length, as well as a dwarf culm. Longitudinal and transverse histological analyses of leaves and internodes revealed that cell division was suppressed in the anticlinal orientation but enhanced in the periclinal orientation in the mutants, while cell size remained unaltered. In addition to defects in cell proliferation, the mutants showed abnormal midrib in leaves. Map-based cloning revealed that nal1-2 is a null allelic mutant of NAL1 since both the whole promoter and a 404-bp fragment in the first exon of NAL1 were deleted, and that a 6-bp fragment was deleted in the mutant nal1-3. We demonstrated that NAL1 functions in the regulation of cell division as early as during leaf primordia initiation. The altered transcript level of G1- and S-phase-specific genes suggested that NAL1 affects cell cycle regulation. Heterogeneous expression of NAL1 in fission yeast (Schizosaccharomyces pombe further supported that NAL1 affects cell division. These results suggest that NAL1 controls leaf width and plant height through its effects on cell division.

  13. Template DNA-strand co-segregation and asymmetric cell division in skeletal muscle stem cells.

    Science.gov (United States)

    Shinin, Vasily; Gayraud-Morel, Barbara; Tajbakhsh, Shahragim

    2009-01-01

    Stem cells are present in all tissues and organs, and are crucial for normal regulated growth. How the pool size of stem cells and their progeny is regulated to establish the tissue prenatally, then maintain it throughout life, is a key question in biology and medicine. The ability to precisely locate stem and progenitors requires defining lineage progression from stem to differentiated cells, assessing the mode of cell expansion and self-renewal and identifying markers to assess the different cell states within the lineage. We have shown that during lineage progression from a quiescent adult muscle satellite cell to a differentiated myofibre, both symmetric and asymmetric divisions take place. Furthermore, we provide evidence that a sub-population of label retaining satellite cells co-segregate template DNA strands to one daughter cell. These findings provide a means of identifying presumed stem and progenitor cells within the lineage. In addition, asymmetric segregation of template DNA and the cytoplasmic protein Numb provides a landmark to define cell behaviour as self-renewal and differentiation decisions are being executed.

  14. Asymmetric cell division and its role in cell fate determination in the green alga Tetraselmis indica

    Digital Repository Service at National Institute of Oceanography (India)

    Arora, M.; Anil, A.C.; Burgess, K.; Delany, J.E.; Mesbahi, E.

    is a mechanism to ensure survival upon exposure to stress. Int. J. Food Microbiol. 78 19-30 De Smet I and Beeckman T 2011 Asymmetric cell division in land plants and algae: the driving force for differentiation. Nature Rev. Mol. Cell Biol. 12 177... of Prasinophytes, but are as evolved as any other green alga or land plant. These organisms share several ultrastructural features with the other core Chlorophytes (Trebouxiophyceae, Ulvophyceae and Chlorophyceae). However, the role of Chlorodendrophycean algae...

  15. Changes in the oligomerization potential of the division inhibitor UgtP co-ordinate Bacillus subtilis cell size with nutrient availability.

    Science.gov (United States)

    Chien, An-Chun; Zareh, Shannon Kian Gharabiklou; Wang, Yan Mei; Levin, Petra Anne

    2012-11-01

    How cells co-ordinate size with growth and development is a major, unresolved question in cell biology. In previous work we identified the glucosyltransferase UgtP as a division inhibitor responsible for increasing the size of Bacillus subtilis cells under nutrient-rich conditions. In nutrient-rich medium, UgtP is distributed more or less uniformly throughout the cytoplasm and concentrated at the cell poles and/or the cytokinetic ring. Under these conditions, UgtP interacts directly with FtsZ to inhibit division and increase cell size. Conversely, under nutrient-poor conditions, UgtP is sequestered away from FtsZ in punctate foci, and division proceeds unimpeded resulting in a reduction in average cell size. Here we report that nutrient-dependent changes in UgtP's oligomerization potential serve as a molecular rheostat to precisely co-ordinate B. subtilis cell size with nutrient availability. Our data indicate UgtP interacts with itself and the essential cell division protein FtsZ in a high-affinity manner influenced in part by UDP glucose, an intracellular proxy for nutrient availability. These findings support a model in which UDP-glc-dependent changes in UgtP's oligomerization potential shift the equilibrium between UgtP•UgtP and UgtP•FtsZ, fine-tuning the amount of FtsZ available for assembly into the cytokinetic ring and with it cell size. © 2012 Blackwell Publishing Ltd.

  16. A general framework for modeling growth and division of mammalian cells.

    Science.gov (United States)

    Gauthier, John H; Pohl, Phillip I

    2011-01-06

    Modeling the cell-division cycle has been practiced for many years. As time has progressed, this work has gone from understanding the basic principles to addressing distinct biological problems, e.g., the nature of the restriction point, how checkpoints operate, the nonlinear dynamics of the cell cycle, the effect of localization, etc. Most models consist of coupled ordinary differential equations developed by the researchers, restricted to deal with the interactions of a limited number of molecules. In the future, cell-cycle modeling--and indeed all modeling of complex biologic processes--will increase in scope and detail. A framework for modeling complex cell-biologic processes is proposed here. The framework is based on two constructs: one describing the entire lifecycle of a molecule and the second describing the basic cellular machinery. Use of these constructs allows complex models to be built in a straightforward manner that fosters rigor and completeness. To demonstrate the framework, an example model of the mammalian cell cycle is presented that consists of several hundred differential equations of simple mass action kinetics. The model calculates energy usage, amino acid and nucleotide usage, membrane transport, RNA synthesis and destruction, and protein synthesis and destruction for 33 proteins to give an in-depth look at the cell cycle. The framework presented here addresses how to develop increasingly descriptive models of complex cell-biologic processes. The example model of cellular growth and division constructed with the framework demonstrates that large structured models can be created with the framework, and these models can generate non-trivial descriptions of cellular processes. Predictions from the example model include those at both the molecular level--e.g., Wee1 spontaneously reactivates--and at the system level--e.g., pathways for timing-critical processes must shut down redundant pathways. A future effort is to automatically estimate

  17. Manganese(II) induces cell division and increases in superoxide dismutase and catalase activities in an aging deinococcal culture

    International Nuclear Information System (INIS)

    Chou, F.I.; Tan, S.T.

    1990-01-01

    Addition of Mn(II) at 2.5 microM or higher to stationary-phase cultures of Deinococcus radiodurans IR was found to trigger at least three rounds of cell division. This Mn(II)-induced cell division (Mn-CD) did not occur when the culture was in the exponential or death phase. The Mn-CD effect produced daughter cells proportionally reduced in size, pigmentation, and radioresistance but proportionally increased in activity and amount of the oxygen toxicity defense enzymes superoxide dismutase and catalase. In addition, the concentration of an Mn-CD-induced protein was found to remain high throughout the entire Mn-CD phase. It was also found that an untreated culture exhibited a growth curve characterized by a very rapid exponential-stationary transition and that cells which had just reached the early stationary phase were synchronous. Our results suggest the presence of an Mn(II)-sensitive mechanism for controlling cell division. The Mn-CD effect appears to be specific to the cation Mn(II) and the radioresistant bacteria, deinococci

  18. From cell differentiation to cell collectives: Bacillus subtilis uses division of labor to migrate.

    Directory of Open Access Journals (Sweden)

    Jordi van Gestel

    2015-04-01

    Full Text Available The organization of cells, emerging from cell-cell interactions, can give rise to collective properties. These properties are adaptive when together cells can face environmental challenges that they separately cannot. One particular challenge that is important for microorganisms is migration. In this study, we show how flagellum-independent migration is driven by the division of labor of two cell types that appear during Bacillus subtilis sliding motility. Cell collectives organize themselves into bundles (called "van Gogh bundles" of tightly aligned cell chains that form filamentous loops at the colony edge. We show, by time-course microscopy, that these loops migrate by pushing themselves away from the colony. The formation of van Gogh bundles depends critically on the synergistic interaction of surfactin-producing and matrix-producing cells. We propose that surfactin-producing cells reduce the friction between cells and their substrate, thereby facilitating matrix-producing cells to form bundles. The folding properties of these bundles determine the rate of colony expansion. Our study illustrates how the simple organization of cells within a community can yield a strong ecological advantage. This is a key factor underlying the diverse origins of multicellularity.

  19. From cell differentiation to cell collectives: Bacillus subtilis uses division of labor to migrate.

    Science.gov (United States)

    van Gestel, Jordi; Vlamakis, Hera; Kolter, Roberto

    2015-04-01

    The organization of cells, emerging from cell-cell interactions, can give rise to collective properties. These properties are adaptive when together cells can face environmental challenges that they separately cannot. One particular challenge that is important for microorganisms is migration. In this study, we show how flagellum-independent migration is driven by the division of labor of two cell types that appear during Bacillus subtilis sliding motility. Cell collectives organize themselves into bundles (called "van Gogh bundles") of tightly aligned cell chains that form filamentous loops at the colony edge. We show, by time-course microscopy, that these loops migrate by pushing themselves away from the colony. The formation of van Gogh bundles depends critically on the synergistic interaction of surfactin-producing and matrix-producing cells. We propose that surfactin-producing cells reduce the friction between cells and their substrate, thereby facilitating matrix-producing cells to form bundles. The folding properties of these bundles determine the rate of colony expansion. Our study illustrates how the simple organization of cells within a community can yield a strong ecological advantage. This is a key factor underlying the diverse origins of multicellularity.

  20. Division of labour in the yeast

    DEFF Research Database (Denmark)

    Wloch-Salamon, Dominika M.; Fisher, Roberta May; Regenberg, Birgitte

    2017-01-01

    . Saccharomyces cerevisiae displays several phenotypes that could be considered a division of labour, including quiescence, apoptosis and biofilm formation, but they have not been explicitly treated as such. We discuss each of these examples, using a definition of division of labour that involves phenotypic...... variation between cells within a population, cooperation between cells performing different tasks and maximization of the inclusive fitness of all cells involved. We then propose future research directions and possible experimental tests using S. cerevisiae as a model organism for understanding the genetic...... mechanisms and selective pressures that can lead to the evolution of the very first stages of a division of labour....

  1. Primary radiation damage and disturbance in cell divisions

    International Nuclear Information System (INIS)

    Kim, Jin Kyu; Lee, Yun-Jong; Kim, Jae-Hun; Petin, Vladislav G.; Nili, Mohammad

    2008-01-01

    Survived cells from a homogeneous population exposed to ionizing radiation form various colonies of different sizes and morphology on a solid nutrient medium, which appear at different time intervals after irradiation. Such a phenomenon agrees well with the modern theory of microdosimetry and classical hit-and-target models of radiobiology. According to the hit-principle, individual cells exposed to the same dose of radiation are damaged in different manners. It means that the survived cells can differ in the content of sublethal damage (hits) produced by the energy absorbed into the cell and which is not enough to give rise to effective radiation damage which is responsible for cell killing or inactivation. In diploid yeast cells, the growth rate of cells from 250 colonies of various sizes appeared at different time intervals after irradiation with 600 Gy of gamma radiation from a 60 Co isotopic source was analyzed. The survival rate after irradiation was 20%. Based on the analyses results, it was possible to categorize the clones grown from irradiated cells according to the number of sub-lesions from 1 to 4. The clones with various numbers of sub-lesions were shown to be different in their viability, radiosensitivity, sensitivity to environmental conditions, and the frequency of recombination and respiratory deficient mutations. Cells from unstable clones exhibited an enhanced radiosensitivity, and an increased portion of morphologically changed cells, nonviable cells and respiration mutants, as well. The degree of expression of the foregoing effects was higher if the number of primary sublethal lesions was greater in the originally irradiated cell. Disturbance in cell division can be characterized by cell inactivation or incorrect distribution of mitochondria between daughter cells. Thus, the suggested methodology of identification of cells with a definite number of primary sublethal lesions will promote further elucidation of the nature of primary radiation

  2. The final cut: cell polarity meets cytokinesis at the bud neck in S. cerevisiae.

    Science.gov (United States)

    Juanes, Maria Angeles; Piatti, Simonetta

    2016-08-01

    Cell division is a fundamental but complex process that gives rise to two daughter cells. It includes an ordered set of events, altogether called "the cell cycle", that culminate with cytokinesis, the final stage of mitosis leading to the physical separation of the two daughter cells. Symmetric cell division equally partitions cellular components between the two daughter cells, which are therefore identical to one another and often share the same fate. In many cases, however, cell division is asymmetrical and generates two daughter cells that differ in specific protein inheritance, cell size, or developmental potential. The budding yeast Saccharomyces cerevisiae has proven to be an excellent system to investigate the molecular mechanisms governing asymmetric cell division and cytokinesis. Budding yeast is highly polarized during the cell cycle and divides asymmetrically, producing two cells with distinct sizes and fates. Many components of the machinery establishing cell polarization during budding are relocalized to the division site (i.e., the bud neck) for cytokinesis. In this review we recapitulate how budding yeast cells undergo polarized processes at the bud neck for cell division.

  3. Pseudomonas aeruginosa Transmigrates at Epithelial Cell-Cell Junctions, Exploiting Sites of Cell Division and Senescent Cell Extrusion.

    Directory of Open Access Journals (Sweden)

    Guillaume Golovkine

    2016-01-01

    Full Text Available To achieve systemic infection, bacterial pathogens must overcome the critical and challenging step of transmigration across epithelial barriers. This is particularly true for opportunistic pathogens such as Pseudomonas aeruginosa, an agent which causes nosocomial infections. Despite extensive study, details on the mechanisms used by this bacterium to transmigrate across epithelial tissues, as well as the entry sites it uses, remain speculative. Here, using real-time microscopy and a model epithelial barrier, we show that P. aeruginosa employs a paracellular transmigration route, taking advantage of altered cell-cell junctions at sites of cell division or when senescent cells are expelled from the cell layer. Once a bacterium transmigrates, it is followed by a cohort of bacteria using the same entry point. The basal compartment is then invaded radially from the initial penetration site. Effective transmigration and propagation require type 4 pili, the type 3 secretion system (T3SS and a flagellum, although flagellum-deficient bacteria can occasionally invade the basal compartment from wounded areas. In the basal compartment, the bacteria inject the T3SS toxins into host cells, disrupting the cytoskeleton and focal contacts to allow their progression under the cells. Thus, P. aeruginosa exploits intrinsic host cell processes to breach the epithelium and invade the subcellular compartment.

  4. Cdc42 and Rab8a are critical for intestinal stem cell division, survival, and differentiation in mice

    DEFF Research Database (Denmark)

    Sakamori, Ryotaro; Das, Soumyashree; Yu, Shiyan

    2012-01-01

    The constant self renewal and differentiation of adult intestinal stem cells maintains a functional intestinal mucosa for a lifetime. However, the molecular mechanisms that regulate intestinal stem cell division and epithelial homeostasis are largely undefined. We report here that the small GTPases...... reminiscent of human microvillus inclusion disease (MVID), a devastating congenital intestinal disorder that results in severe nutrient deprivation. Further analysis revealed that Cdc42-deficient stem cells had cell division defects, reduced capacity for clonal expansion and differentiation into Paneth cells...... suggest that defects of the stem cell niche can cause MVID. This hypothesis represents a conceptual departure from the conventional view of this disease, which has focused on the affected enterocytes, and suggests stem cell-based approaches could be beneficial to infants with this often lethal condition....

  5. Prophage induction and cell division in E. coli. Pt. 3

    International Nuclear Information System (INIS)

    George, J.; Castellazzi, M.; Buttin, G.

    1975-01-01

    In E. coli K12, cell filamentation promoted by tif is enhanced by the lon mutation; in contrast, prophage induction and repair of UV-irradiated phage lambda, also promoted by tif, are not affected by lon. From a tif lon double mutant, 'revertants' having recovered the ability to divide at 41 0 were isolated, among which most (95%) had also lost heir Lon filamentous phenotype after ultraviolet (UV) irradiation. From these 95% of revertants 94% are suppressed for the whole Tif phenotype, by additional mutations that render them deficient in DNA repair, as judged from their high UV sensitivity; some have been characterized as recA mutants. 1% have recovered a control on cell division at 41% or after UV irradiation by means of secondary mutations altering neither the other phenotypic properties of tif and lon, nor the repair and recombination ability of the cells: in particular, this class of 'revertants' remains thermoinducible upon lysogenisation; the mutations which specifically supress filamentation have been mapped at two loci, sfiA and sfiB, cotransducible respectively with pyrD and leu. In the remaining 5% of revertants that still exhibit an UV-induced filamentous growth, 3% can be tentatively classified as true tif + revertants; 2% behave as tif thermodependent revertants, showing suppression of Tif (and Lon) phenotype only at 41 0 : 2 recAts have been identified in this class. Non-lysogenic tif lon sfi and tif sfi strains remain viable during prolonged growth at 41 0 . Under these conditions, tif expresses mutator properties, which can be conveniently analyzed in this sfi background. The action of tif, lon and sfi mutations is tentatively interpreted on the basis of a negative control of cell division specifically associated with DNA repair. (orig.) [de

  6. Division of labour in the yeast: Saccharomyces cerevisiae.

    Science.gov (United States)

    Wloch-Salamon, Dominika M; Fisher, Roberta M; Regenberg, Birgitte

    2017-10-01

    Division of labour between different specialized cell types is a central part of how we describe complexity in multicellular organisms. However, it is increasingly being recognized that division of labour also plays an important role in the lives of predominantly unicellular organisms. Saccharomyces cerevisiae displays several phenotypes that could be considered a division of labour, including quiescence, apoptosis and biofilm formation, but they have not been explicitly treated as such. We discuss each of these examples, using a definition of division of labour that involves phenotypic variation between cells within a population, cooperation between cells performing different tasks and maximization of the inclusive fitness of all cells involved. We then propose future research directions and possible experimental tests using S. cerevisiae as a model organism for understanding the genetic mechanisms and selective pressures that can lead to the evolution of the very first stages of a division of labour. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  7. Microbial mutagenesis and cell division

    International Nuclear Information System (INIS)

    Adler, H.I.; Carrasco, A.; Nagel, R.; Gill, J.S.; Crow, W.D.

    1982-01-01

    Our group has been pursuing three related objectives. The first of these is a study of a mechanism by which the bacterium Escherichia coli repairs radiation-induced damage. In particular, we have observed that cells of certain strains of this bacterium, mutant at the lon locus, can be restored to viability after exposure to ionizing radiation if they are incubated in a nutrient medium to which a preparation of partially purified bacterial membranes has been added. These preparations stimulate division by producing chemical alterations in the nutrient medium and simultaneously creating a highly anaerobic environment. A second objective of the group was to make use of lon mutants for a rapid, sensitive, and inexpensive assay for chemical mutagens. Cells of lon mutants form long multinucleate filaments if exposed to a variety of agents that react with DNA. These filaments can readily be observed microscopically 2 to 3 h after exposure to the suspect agent. A third objective of our group has been to make use of the oxygen reducing properties of bacterial membrane preparations to stimulate the growth of anaerobic bacteria. Our general goal is to develop basic microbiological techniques that will facilitate the application of genetic manipulation methods to important anaerobic species. To this end, we have developed a method, based on the use of membranes, that allows us to grow liquid cultures of Clostridium acetobutylicum from very small inocula to high titers without elaborate chemical or physical methods for excluding oxygen. We have also developed efficient methods for plating this bacterium that do not require the use of anaerobic incubators

  8. A specific role for the ZipA protein in cell division: stabilization of the FtsZ protein.

    Science.gov (United States)

    Pazos, Manuel; Natale, Paolo; Vicente, Miguel

    2013-02-01

    In Escherichia coli, the cell division protein FtsZ is anchored to the cytoplasmic membrane by the action of the bitopic membrane protein ZipA and the cytoplasmic protein FtsA. Although the presence of both ZipA and FtsA is strictly indispensable for cell division, an FtsA gain-of-function mutant FtsA* (R286W) can bypass the ZipA requirement for cell division. This observation casts doubts on the role of ZipA and its need for cell division. Maxicells are nucleoid-free bacterial cells used as a whole cell in vitro system to probe protein-protein interactions without the need of protein purification. We show that ZipA protects FtsZ from the ClpXP-directed degradation observed in E. coli maxicells and that ZipA-stabilized FtsZ forms membrane-attached spiral-like structures in the bacterial cytoplasm. The overproduction of the FtsZ-binding ZipA domain is sufficient to protect FtsZ from degradation, whereas other C-terminal ZipA partial deletions lacking it are not. Individual overproduction of the proto-ring component FtsA or its gain-of-function mutant FtsA* does not result in FtsZ protection. Overproduction of FtsA or FtsA* together with ZipA does not interfere with the FtsZ protection. Moreover, neither FtsA nor FtsA* protects FtsZ when overproduced together with ZipA mutants lacking the FZB domain. We propose that ZipA protects FtsZ from degradation by ClpP by making the FtsZ site of interaction unavailable to the ClpX moiety of the ClpXP protease. This role cannot be replaced by either FtsA or FtsA*, suggesting a unique function for ZipA in proto-ring stability.

  9. Nanoscale imaging of the growth and division of bacterial cells on planar substrates with the atomic force microscope

    Energy Technology Data Exchange (ETDEWEB)

    Van Der Hofstadt, M. [Institut de Bioenginyeria de Catalunya (IBEC), C/ Baldiri i Reixac 11-15, 08028 Barcelona (Spain); Hüttener, M.; Juárez, A. [Institut de Bioenginyeria de Catalunya (IBEC), C/ Baldiri i Reixac 11-15, 08028 Barcelona (Spain); Departament de Microbiologia, Universitat de Barcelona, Avinguda Diagonal 645, 08028 Barcelona (Spain); Gomila, G., E-mail: ggomila@ibecbarcelona.eu [Institut de Bioenginyeria de Catalunya (IBEC), C/ Baldiri i Reixac 11-15, 08028 Barcelona (Spain); Departament d' Electronica, Universitat de Barcelona, C/ Marti i Franqués 1, 08028 Barcelona (Spain)

    2015-07-15

    With the use of the atomic force microscope (AFM), the Nanomicrobiology field has advanced drastically. Due to the complexity of imaging living bacterial processes in their natural growing environments, improvements have come to a standstill. Here we show the in situ nanoscale imaging of the growth and division of single bacterial cells on planar substrates with the atomic force microscope. To achieve this, we minimized the lateral shear forces responsible for the detachment of weakly adsorbed bacteria on planar substrates with the use of the so called dynamic jumping mode with very soft cantilever probes. With this approach, gentle imaging conditions can be maintained for long periods of time, enabling the continuous imaging of the bacterial cell growth and division, even on planar substrates. Present results offer the possibility to observe living processes of untrapped bacteria weakly attached to planar substrates. - Highlights: • Gelatine coatings used to weakly attach bacterial cells onto planar substrates. • Use of the dynamic jumping mode as a non-perturbing bacterial imaging mode. • Nanoscale resolution imaging of unperturbed single living bacterial cells. • Growth and division of single bacteria cells on planar substrates observed.

  10. The Antibacterial Cell Division Inhibitor PC190723 Is an FtsZ Polymer-stabilizing Agent That Induces Filament Assembly and Condensation*

    OpenAIRE

    Andreu, José M.; Schaffner-Barbero, Claudia; Huecas, Sonia; Alonso, Dulce; Lopez-Rodriguez, María L.; Ruiz-Avila, Laura B.; Núñez-Ramírez, Rafael; Llorca, Oscar; Martín-Galiano, Antonio J.

    2010-01-01

    Cell division protein FtsZ can form single-stranded filaments with a cooperative behavior by self-switching assembly. Subsequent condensation and bending of FtsZ filaments are important for the formation and constriction of the cytokinetic ring. PC190723 is an effective bactericidal cell division inhibitor that targets FtsZ in the pathogen Staphylococcus aureus and Bacillus subtilis and does not affect Escherichia coli cells, which apparently binds to a zone equivalent to the binding site of ...

  11. Divisions of general practice in Australia: how do they measure up in the international context?

    Science.gov (United States)

    Smith, Judith; Sibthorpe, Beverly

    2007-07-13

    Since the late 1980s, there has been evidence of an international trend towards more organised primary care. This has taken a number of forms including the emergence of primary care organisations. Underpinning such developments is an inherent belief in evidence that suggests that well-developed primary care is associated with improved health outcomes and greater cost-effectiveness within health systems. In Australia, primary care organisations have emerged as divisions of general practice. These are professionally-led, regionally-based, and largely government-funded voluntary associations of general practitioners that seek to co-ordinate local primary care services, and improve the quality of care and health outcomes for local communities. In this paper, we examine and debate the development of divisions in the international context, using six roles of primary care organisations outlined in published research. The six roles that are used as the basis for the critique are the ability of primary care organisations to: improve health outcomes; manage demand and control costs; engage primary care physicians; enable greater integration of health services; develop more accessible services in community and primary care settings; and enable greater scrutiny and assurance of quality of primary care services. We conclude that there has been an evolutionary approach to divisions' development and they now appear embedded as geographically-based planning and development organisations within the Australian primary health care system. The Australian Government has to date been cautious in its approach to intervention in divisions' direction and performance. However, options for the next phase include: making greater use of contracts between government and divisions; introducing and extending proposed national quality targets for divisions, linked with financial or other incentives for performance; government sub-contracting with state-based organisations to act as purchasers of

  12. Evolutionary transition towards permanent chloroplasts? - Division of kleptochloroplasts in starved cells of two species of Dinophysis (Dinophyceae.

    Directory of Open Access Journals (Sweden)

    Pernille Møller Rusterholz

    Full Text Available Species within the marine toxic dinoflagellate genus Dinophysis are phagotrophic organisms that exploit chloroplasts (kleptochloroplasts from other protists to perform photosynthesis. Dinophysis spp. acquire the kleptochloroplasts from the ciliate Mesodinium rubrum, which in turn acquires the chloroplasts from a unique clade of cryptophytes. Dinophysis spp. digest the prey nuclei and all other cell organelles upon ingestion (except the kleptochloroplasts and they are therefore believed to constantly acquire new chloroplasts as the populations grow. Previous studies have, however, indicated that Dinophysis can keep the kleptochloroplasts active during long term starvation and are able to produce photosynthetic pigments when exposed to prey starvation. This indicates a considerable control over the kleptochloroplasts and the ability of Dinophysis to replicate its kleptochloroplasts was therefore re-investigated in detail in this study. The kleptochloroplasts of Dinophysis acuta and Dinophysis acuminata were analyzed using confocal microscopy and 3D bioimaging software during long term starvation experiments. The cell concentrations were monitored to confirm cell divisions and samples were withdrawn each time a doubling had occurred. The results show direct evidence of kleptochloroplastidic division and that the decreases in total kleptochloroplast volume, number of kleptochloroplasts and number of kleptochloroplast centers were not caused by dilution due to cell divisions. This is the first report of division of kleptochloroplasts in any protist without the associated prey nuclei. This indicates that Dinophysis spp. may be in a transitional phase towards possessing permanent chloroplasts, which thereby potentially makes it a key organism to understand the evolution of phototrophic protists.

  13. Regulation of the Min Cell Division Inhibition Complex by the Rcs Phosphorelay in Proteus mirabilis.

    Science.gov (United States)

    Howery, Kristen E; Clemmer, Katy M; Şimşek, Emrah; Kim, Minsu; Rather, Philip N

    2015-08-01

    A key regulator of swarming in Proteus mirabilis is the Rcs phosphorelay, which represses flhDC, encoding the master flagellar regulator FlhD4C2. Mutants in rcsB, the response regulator in the Rcs phosphorelay, hyperswarm on solid agar and differentiate into swarmer cells in liquid, demonstrating that this system also influences the expression of genes central to differentiation. To gain a further understanding of RcsB-regulated genes involved in swarmer cell differentiation, transcriptome sequencing (RNA-Seq) was used to examine the RcsB regulon. Among the 133 genes identified, minC and minD, encoding cell division inhibitors, were identified as RcsB-activated genes. A third gene, minE, was shown to be part of an operon with minCD. To examine minCDE regulation, the min promoter was identified by 5' rapid amplification of cDNA ends (5'-RACE), and both transcriptional lacZ fusions and quantitative real-time reverse transcriptase (qRT) PCR were used to confirm that the minCDE operon was RcsB activated. Purified RcsB was capable of directly binding the minC promoter region. To determine the role of RcsB-mediated activation of minCDE in swarmer cell differentiation, a polar minC mutation was constructed. This mutant formed minicells during growth in liquid, produced shortened swarmer cells during differentiation, and exhibited decreased swarming motility. This work describes the regulation and role of the MinCDE cell division system in P. mirabilis swarming and swarmer cell elongation. Prior to this study, the mechanisms that inhibit cell division and allow swarmer cell elongation were unknown. In addition, this work outlines for the first time the RcsB regulon in P. mirabilis. Taken together, the data presented in this study begin to address how P. mirabilis elongates upon contact with a solid surface. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  14. A specific role of iron in promoting meristematic cell division during adventitious root formation.

    Science.gov (United States)

    Hilo, Alexander; Shahinnia, Fahimeh; Druege, Uwe; Franken, Philipp; Melzer, Michael; Rutten, Twan; von Wirén, Nicolaus; Hajirezaei, Mohammad-Reza

    2017-07-10

    Adventitious root (AR) formation is characterized by a sequence of physiological and morphological processes and determined by external factors, including mineral nutrition, the impacts of which remain largely elusive. Morphological and anatomical evaluation of the effects of mineral elements on AR formation in leafy cuttings of Petunia hybrida revealed a striking stimulation by iron (Fe) and a promotive action of ammonium (NH4+). The optimal application period for these nutrients corresponded to early division of meristematic cells in the rooting zone and coincided with increased transcript levels of mitotic cyclins. Fe-localization studies revealed an enhanced allocation of Fe to the nuclei of meristematic cells in AR initials. NH4+ supply promoted AR formation to a lesser extent, most likely by favoring the availability of Fe. We conclude that Fe acts locally by promoting cell division in the meristematic cells of AR primordia. These results highlight a specific biological function of Fe in AR development and point to an unexploited importance of Fe for the vegetative propagation of plants from cuttings. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  15. Colocalization and interaction between elongasome and divisome during a preparative cell division phase in Escherichia coli

    NARCIS (Netherlands)

    Ploeg, van der R.; Verheul, J.; Vischer, N.O.E.; Alexeeva, S.V.; Hoogendoorn, E.; Postma, M.; Banzhaf, M.; Vollmer, W.; Blaauwen, den T.

    2013-01-01

    The rod-shaped bacterium Escherichia coli grows by insertion of peptidoglycan into the lateral wall during cell elongation and synthesis of new poles during cell division. The monofunctional transpeptidases PBP2 and PBP3 are part of specialized protein complexes called elongasome and divisome,

  16. A local maximum in gibberellin levels regulates maize leaf growth by spatial control of cell division.

    Science.gov (United States)

    Nelissen, Hilde; Rymen, Bart; Jikumaru, Yusuke; Demuynck, Kirin; Van Lijsebettens, Mieke; Kamiya, Yuji; Inzé, Dirk; Beemster, Gerrit T S

    2012-07-10

    Plant growth rate is largely determined by the transition between the successive phases of cell division and expansion. A key role for hormone signaling in determining this transition was inferred from genetic approaches and transcriptome analysis in the Arabidopsis root tip. We used the developmental gradient at the maize leaf base as a model to study this transition, because it allows a direct comparison between endogenous hormone concentrations and the transitions between dividing, expanding, and mature tissue. Concentrations of auxin and cytokinins are highest in dividing tissues, whereas bioactive gibberellins (GAs) show a peak at the transition zone between the division and expansion zone. Combined metabolic and transcriptomic profiling revealed that this GA maximum is established by GA biosynthesis in the division zone (DZ) and active GA catabolism at the onset of the expansion zone. Mutants defective in GA synthesis and signaling, and transgenic plants overproducing GAs, demonstrate that altering GA levels specifically affects the size of the DZ, resulting in proportional changes in organ growth rates. This work thereby provides a novel molecular mechanism for the regulation of the transition from cell division to expansion that controls organ growth and size. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. Colonic stem cell data are consistent with the immortal model of stem cell division under non-random strand segregation.

    Science.gov (United States)

    Walters, K

    2009-06-01

    Colonic stem cells are thought to reside towards the base of crypts of the colon, but their numbers and proliferation mechanisms are not well characterized. A defining property of stem cells is that they are able to divide asymmetrically, but it is not known whether they always divide asymmetrically (immortal model) or whether there are occasional symmetrical divisions (stochastic model). By measuring diversity of methylation patterns in colon crypt samples, a recent study found evidence in favour of the stochastic model, assuming random segregation of stem cell DNA strands during cell division. Here, the effect of preferential segregation of the template strand is considered to be consistent with the 'immortal strand hypothesis', and explore the effect on conclusions of previously published results. For a sample of crypts, it is shown how, under the immortal model, to calculate mean and variance of the number of unique methylation patterns allowing for non-random strand segregation and compare them with those observed. The calculated mean and variance are consistent with an immortal model that incorporates non-random strand segregation for a range of stem cell numbers and levels of preferential strand segregation. Allowing for preferential strand segregation considerably alters previously published conclusions relating to stem cell numbers and turnover mechanisms. Evidence in favour of the stochastic model may not be as strong as previously thought.

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

    Directory of Open Access Journals (Sweden)

    Laura Terzaghi

    2015-07-01

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

  19. Effect of microgravity environment on cell wall regeneration, cell divisions, growth, and differentiation of plants from protoplasts (7-IML-1)

    Science.gov (United States)

    Rasmussen, Ole

    1992-01-01

    The primary goal of this project is to investigate if microgravity has any influence on growth and differentiation of protoplasts. Formation of new cell walls on rapeseed protoplasts takes place within the first 24 hours after isolation. Cell division can be observed after 2-4 days and formation of cell aggregates after 5-7 days. Therefore, it is possible during the 7 day IML-1 Mission to investigate if cell wall formation, cell division, and cell differentiation are influenced by microgravity. Protoplasts of rapeseeds and carrot will be prepared shortly before launch and injected into 0.6 ml polyethylene bags. Eight bags are placed in an aluminum block inside the ESA Type 1 container. The containers are placed at 4 C in PTCU's and transferred to orbiter mid-deck. At 4 C all cell processes are slowed down, including cell wall formation. Latest access to the shuttle will be 12 hours before launch. In orbit the containers will be transferred from the PTC box to the 22 C Biorack incubator. The installation of a 1 g centrifuge in Biorack will make it possible to distinguish between effects of near weightlessness and effects caused by cosmic radiation and other space flight factors including vibrations. Parallel control experiments will be carried out on the ground. Other aspects of the experiment are discussed.

  20. Cell cycle related /sup 125/IUDR-induced-division delay

    International Nuclear Information System (INIS)

    Scheniderman, M.H.; Hofer, K.G.

    1987-01-01

    A series of experiments were run to determine if /sup 125/I-decays, in /sup 125/IUdR labeled DNA, specifically accumulated at 1, 3, 5, 7 and 9 hours after plating labeled mitotic cells caused a change in the rate or time of cell entry into mitosis. To accomplish this, a pool of labeled mitotic cells was selected in mitosis and plated in replicate flasks. /sup 125/I decays were accumulated in groups of cells by cooling (4 0 C) for 2 hours starting at the designated times. After rewarding, colcemid was added to arrest cells in mitosis. The rate of cell progression into mitosis for each cell cycle time of accumulation was determined by scoring the mitotic index of cells sampled as a function of time after addition of the colcemid. The results are summarized: (1) Decays from /sup 125/I in /sup 125/I(UdR) labeled DNA reduced the rate of cell progression into mitosis and delayed the time of initiation of mitosis. (2) The reduced rate of progression and the delayed time of initiation of mitosis were independent of the cell cycle time that /sup 125/I-decays were accumulated. (3) The reduced rate of progression after cell cycle accumulation of /sup 125/I decay was statistically indistinguishable from the corresponding controls. (4) The delayed initiation of mitosis after specific cell cycle accumulation of /sup 125/I- decays was greater than the corresponding control. The relationship of these data to DNA and non-DNA division delay target(s) is emphasized

  1. From HeLa cell division to infectious diarrhoea

    International Nuclear Information System (INIS)

    Stephen, J.; Osborne, M.P.; Spencer, A.J.; Warley, A.

    1990-01-01

    Hela S3 cells were grown in suspension both randomly and, synchronously using hydroxyurea which blocks cells at the G1/S interface. Cryosections were prepared, freeze-dried and analyzed by X-ray microanalysis. As cells moved into S and through M phases [Na] and [Cl] increased; both returned to normal levels upon re-entering G1 phase. The Na/K ratio was 1:1 in G1 phase. Infection of HeLa S3 cells in G1 phase with vaccinia virus resulted in no change in intracellular [Na]. Infection of neonatal mice with murine rotavirus was localized to villus tip enterocytes and gave rise to diarrhoea which was maximal at 72h post-infection (p.i.). Diarrhoea was preceded by ischemia of villi (18-42h p.i.) and villus shortening (maximal at 42h p.i.), and was also coincident with a dramatic regrowth of villi. At 48h p.i. a proliferative zone of electron lucent cells was observed in villus base regions. Cryosections of infected gut, taken before, during, and after infection, together with corresponding age-matched controls, were freeze-dried and analysed by X-ray microanalysis. At 48h p.i. electron lucent villus base cells were shown to be more hydrated, and, to contain higher levels of both Na and Cl and lower levels of P, S, K and Mg than corresponding control cells. These studies increase confidence in the use of X-ray microanalysis in studying biological systems, provide some insight into the process of cell division, and constitute the basis of a new concept of diarrhoeal secretion.27 references

  2. From HeLa cell division to infectious diarrhoea

    Energy Technology Data Exchange (ETDEWEB)

    Stephen, J.; Osborne, M.P.; Spencer, A.J.; Warley, A. (Univ. of Birmingham (England))

    1990-09-01

    Hela S3 cells were grown in suspension both randomly and, synchronously using hydroxyurea which blocks cells at the G1/S interface. Cryosections were prepared, freeze-dried and analyzed by X-ray microanalysis. As cells moved into S and through M phases (Na) and (Cl) increased; both returned to normal levels upon re-entering G1 phase. The Na/K ratio was 1:1 in G1 phase. Infection of HeLa S3 cells in G1 phase with vaccinia virus resulted in no change in intracellular (Na). Infection of neonatal mice with murine rotavirus was localized to villus tip enterocytes and gave rise to diarrhoea which was maximal at 72h post-infection (p.i.). Diarrhoea was preceded by ischemia of villi (18-42h p.i.) and villus shortening (maximal at 42h p.i.), and was also coincident with a dramatic regrowth of villi. At 48h p.i. a proliferative zone of electron lucent cells was observed in villus base regions. Cryosections of infected gut, taken before, during, and after infection, together with corresponding age-matched controls, were freeze-dried and analysed by X-ray microanalysis. At 48h p.i. electron lucent villus base cells were shown to be more hydrated, and, to contain higher levels of both Na and Cl and lower levels of P, S, K and Mg than corresponding control cells. These studies increase confidence in the use of X-ray microanalysis in studying biological systems, provide some insight into the process of cell division, and constitute the basis of a new concept of diarrhoeal secretion.27 references.

  3. Translational Control of Cell Division by Elongator

    Directory of Open Access Journals (Sweden)

    Fanelie Bauer

    2012-05-01

    Full Text Available Elongator is required for the synthesis of the mcm5s2 modification found on tRNAs recognizing AA-ending codons. In order to obtain a global picture of the role of Elongator in translation, we used reverse protein arrays to screen the fission yeast proteome for translation defects. Unexpectedly, this revealed that Elongator inactivation mainly affected three specific functional groups including proteins implicated in cell division. The absence of Elongator results in a delay in mitosis onset and cytokinesis defects. We demonstrate that the kinase Cdr2, which is a central regulator of mitosis and cytokinesis, is under translational control by Elongator due to the Lysine codon usage bias of the cdr2 coding sequence. These findings uncover a mechanism by which the codon usage, coupled to tRNA modifications, fundamentally contributes to gene expression and cellular functions.

  4. Auxin as an inducer of asymmetrical division generating the subsidiary cells in stomatal complexes of Zea mays.

    Science.gov (United States)

    Livanos, Pantelis; Giannoutsou, Eleni; Apostolakos, Panagiotis; Galatis, Basil

    2015-01-01

    The data presented in this work revealed that in Zea mays the exogenously added auxins indole-3-acetic acid (IAA) and 1-napthaleneacetic acid (NAA), promoted the establishment of subsidiary cell mother cell (SMC) polarity and the subsequent subsidiary cell formation, while treatment with auxin transport inhibitors 2,3,5-triiodobenzoic acid (TIBA) and 1-napthoxyacetic acid (NOA) specifically blocked SMC polarization and asymmetrical division. Furthermore, in young guard cell mother cells (GMCs) the PIN1 auxin efflux carriers were mainly localized in the transverse GMC faces, while in the advanced GMCs they appeared both in the transverse and the lateral ones adjacent to SMCs. Considering that phosphatidyl-inositol-3-kinase (PI3K) is an active component of auxin signal transduction and that phospholipid signaling contributes in the establishment of polarity, treatments with the specific inhibitor of the PI3K LY294002 were carried out. The presence of LY294002 suppressed polarization of SMCs and prevented their asymmetrical division, whereas combined treatment with exogenously added NAA and LY294002 restricted the promotional auxin influence on subsidiary cell formation. These findings support the view that auxin is involved in Z. mays subsidiary cell formation, probably functioning as inducer of the asymmetrical SMC division. Collectively, the results obtained from treatments with auxin transport inhibitors and the appearance of PIN1 proteins in the lateral GMC faces indicate a local transfer of auxin from GMCs to SMCs. Moreover, auxin signal transduction seems to be mediated by the catalytic function of PI3K.

  5. ParA and ParB coordinate chromosome segregation with cell elongation and division during Streptomyces sporulation

    Science.gov (United States)

    Donczew, Magdalena; Mackiewicz, Paweł; Wróbel, Agnieszka; Flärdh, Klas; Zakrzewska-Czerwińska, Jolanta

    2016-01-01

    In unicellular bacteria, the ParA and ParB proteins segregate chromosomes and coordinate this process with cell division and chromosome replication. During sporulation of mycelial Streptomyces, ParA and ParB uniformly distribute multiple chromosomes along the filamentous sporogenic hyphal compartment, which then differentiates into a chain of unigenomic spores. However, chromosome segregation must be coordinated with cell elongation and multiple divisions. Here, we addressed the question of whether ParA and ParB are involved in the synchronization of cell-cycle processes during sporulation in Streptomyces. To answer this question, we used time-lapse microscopy, which allows the monitoring of growth and division of single sporogenic hyphae. We showed that sporogenic hyphae stop extending at the time of ParA accumulation and Z-ring formation. We demonstrated that both ParA and ParB affect the rate of hyphal extension. Additionally, we showed that ParA promotes the formation of massive nucleoprotein complexes by ParB. We also showed that FtsZ ring assembly is affected by the ParB protein and/or unsegregated DNA. Our results indicate the existence of a checkpoint between the extension and septation of sporogenic hyphae that involves the ParA and ParB proteins. PMID:27248800

  6. Mechanical Regulation in Cell Division and in Neurotransmitter Release

    Science.gov (United States)

    Thiyagarajan, Sathish

    During their lifecycle, cells must produce forces which play important roles in several subcellular processes. Force-producing components are organized into macromolecular assemblies of proteins that are often dynamic, and are constructed or disassembled in response to various signals. The forces themselves may directly be involved in subcellular mechanics, or they may influence mechanosensing proteins either within or outside these structures. These proteins play different roles: they may ensure the stability of the force-producing structure, or they may send signals to a coupled process. The generation and sensing of subcellular forces is an active research topic, and this thesis focusses on the roles of these forces in two key areas: cell division and neurotransmitter release. The first part of the thesis deals with the effect of force on cell wall growth regulation during division in the fission yeast Schizosaccharomyces pombe, a cigar-shaped, unicellular organism. During cytokinesis, the last stage of cell division in which the cell physically divides into two, a tense cytokinetic ring anchored to the cellular membrane assembles and constricts, accompanied by the inward centripetal growth of new cell wall, called septum, in the wake of the inward-moving membrane. The contour of the septum hole maintains its circularity as it reduces in size--an indication of regulated growth. To characterize the cell wall growth process, we performed image analysis on contours of the leading edge of the septum obtained via fluorescence microscopy in the labs of our collaborators. We quantified the deviations from circularity using the edge roughness. The roughness was spatially correlated, suggestive of regulated growth. We hypothesized that the cell wall growers are mechanosensitive and respond to the force exerted by the ring. A mathematical model based on this hypothesis then showed that this leads to corrections of roughness in a curvature-dependent fashion. Thus, one of

  7. Role of cell division and self-propulsion in self-organization of 2D cell co-cultures

    Science.gov (United States)

    Das, Moumita; Dey, Supravat; Wu, Mingming; Ma, Minglin

    Self-organization of cells is a key process in developmental and cancer biology. The differential adhesion hypothesis (DAH), which assumes cells as equilibrium liquid droplets and relates the self-assembly of cells to differences in inter-cellular adhesiveness, has been very successful in explaining cellular organization during morphogenesis where neighboring cells have the same non-equilibrium properties (motility, proliferation rate). However, recently it has been experimentally shown that for a co-culture of two different cell types proliferating at different rates, the resulting spatial morphologies cannot be explained using the DAH alone. Motivated by this, we develop and study a two-dimensional model of a cell co-culture that includes cell division and self-propulsion in addition to cell-cell adhesion, and systemically study how cells with significantly different adhesion, motility, and proliferation rate dynamically organize themselves in a spatiotemporal and context-dependent manner. Our results may help to understand how differential equilibrium and non-equilibrium properties cooperate and compete leading to different morphologies during tumor development, with important consequences for invasion and metastasis

  8. In tobacco BY-2 cells xyloglucan oligosaccharides alter the expression of genes involved in cell wall metabolism, signalling, stress responses, cell division and transcriptional control.

    Science.gov (United States)

    González-Pérez, Lien; Perrotta, Lara; Acosta, Alexis; Orellana, Esteban; Spadafora, Natasha; Bruno, Leonardo; Bitonti, Beatrice M; Albani, Diego; Cabrera, Juan Carlos; Francis, Dennis; Rogers, Hilary J

    2014-10-01

    Xyloglucan oligosaccharides (XGOs) are breakdown products of XGs, the most abundant hemicelluloses of the primary cell walls of non-Poalean species. Treatment of cell cultures or whole plants with XGOs results in accelerated cell elongation and cell division, changes in primary root growth, and a stimulation of defence responses. They may therefore act as signalling molecules regulating plant growth and development. Previous work suggests an interaction with auxins and effects on cell wall loosening, however their mode of action is not fully understood. The effect of an XGO extract from tamarind (Tamarindus indica) on global gene expression was therefore investigated in tobacco BY-2 cells using microarrays. Over 500 genes were differentially regulated with similar numbers and functional classes of genes up- and down-regulated, indicating a complex interaction with the cellular machinery. Up-regulation of a putative XG endotransglycosylase/hydrolase-related (XTH) gene supports the mechanism of XGO action through cell wall loosening. Differential expression of defence-related genes supports a role for XGOs as elicitors. Changes in the expression of genes related to mitotic control and differentiation also support previous work showing that XGOs are mitotic inducers. XGOs also affected expression of several receptor-like kinase genes and transcription factors. Hence, XGOs have significant effects on expression of genes related to cell wall metabolism, signalling, stress responses, cell division and transcriptional control.

  9. Peptidoglycan architecture can specify division planes in Staphylococcus aureus.

    Science.gov (United States)

    Turner, Robert D; Ratcliffe, Emma C; Wheeler, Richard; Golestanian, Ramin; Hobbs, Jamie K; Foster, Simon J

    2010-06-15

    Division in Staphylococci occurs equatorially and on specific sequentially orthogonal planes in three dimensions, resulting, after incomplete cell separation, in the 'bunch of grapes' cluster organization that defines the genus. The shape of Staphylococci is principally maintained by peptidoglycan. In this study, we use Atomic Force Microscopy (AFM) and fluorescence microscopy with vancomycin labelling to examine purified peptidoglycan architecture and its dynamics in Staphylococcus aureus and correlate these with the cell cycle. At the presumptive septum, cells were found to form a large belt of peptidoglycan in the division plane before the centripetal formation of the septal disc; this often had a 'piecrust' texture. After division, the structures remain as orthogonal ribs, encoding the location of past division planes in the cell wall. We propose that this epigenetic information is used to enable S. aureus to divide in sequentially orthogonal planes, explaining how a spherical organism can maintain division plane localization with fidelity over many generations.

  10. Temporal controls of the asymmetric cell division cycle in Caulobacter crescentus.

    Directory of Open Access Journals (Sweden)

    Shenghua Li

    2009-08-01

    Full Text Available The asymmetric cell division cycle of Caulobacter crescentus is orchestrated by an elaborate gene-protein regulatory network, centered on three major control proteins, DnaA, GcrA and CtrA. The regulatory network is cast into a quantitative computational model to investigate in a systematic fashion how these three proteins control the relevant genetic, biochemical and physiological properties of proliferating bacteria. Different controls for both swarmer and stalked cell cycles are represented in the mathematical scheme. The model is validated against observed phenotypes of wild-type cells and relevant mutants, and it predicts the phenotypes of novel mutants and of known mutants under novel experimental conditions. Because the cell cycle control proteins of Caulobacter are conserved across many species of alpha-proteobacteria, the model we are proposing here may be applicable to other genera of importance to agriculture and medicine (e.g., Rhizobium, Brucella.

  11. Temporal controls of the asymmetric cell division cycle in Caulobacter crescentus.

    Science.gov (United States)

    Li, Shenghua; Brazhnik, Paul; Sobral, Bruno; Tyson, John J

    2009-08-01

    The asymmetric cell division cycle of Caulobacter crescentus is orchestrated by an elaborate gene-protein regulatory network, centered on three major control proteins, DnaA, GcrA and CtrA. The regulatory network is cast into a quantitative computational model to investigate in a systematic fashion how these three proteins control the relevant genetic, biochemical and physiological properties of proliferating bacteria. Different controls for both swarmer and stalked cell cycles are represented in the mathematical scheme. The model is validated against observed phenotypes of wild-type cells and relevant mutants, and it predicts the phenotypes of novel mutants and of known mutants under novel experimental conditions. Because the cell cycle control proteins of Caulobacter are conserved across many species of alpha-proteobacteria, the model we are proposing here may be applicable to other genera of importance to agriculture and medicine (e.g., Rhizobium, Brucella).

  12. Exposure of Human CD8+ T Cells to Type-2 Cytokines Impairs Division and Differentiation and Induces Limited Polarization

    Directory of Open Access Journals (Sweden)

    Annette Fox

    2018-05-01

    Full Text Available Effector CD8+ T cells generally produce type-1 cytokines and mediators of the perforin/granzyme cytolytic pathway, yet type-2-polarized CD8+ cells (Tc2 are detected in type-2 (T2 cytokine-driven diseases such as asthma. It is unclear whether T2 cytokine exposure during activation is sufficient to polarize human CD8+ T cells. To address this question, a protocol was developed for high-efficiency activation of human CD8+ T cells in which purified single cells or populations were stimulated with plate-bound anti-CD3 and anti-CD11a mAb for up to 8 days in T2 polarizing or neutral conditions, before functional analysis. Activation of CD8+ naïve T cells (TN in T2 compared with neutral conditions decreased the size of single-cell clones, although early division kinetics were equivalent, indicating an effect on overall division number. Activation of TN in T2 conditions followed by brief anti-CD3 mAb restimulation favored expression of T2 cytokines, GATA3 and Eomes, and lowered expression of type-1 cytokines, Prf1, Gzmb, T-BET, and Prdm1. However, IL-4 was only weakly expressed, and PMA and ionomycin restimulation favored IFN-γ over IL-4 expression. Activation of TN in T2 compared with neutral conditions prevented downregulation of costimulatory (CD27, CD28 and lymph-node homing receptors (CCR7 and CD95 acquisition, which typically occur during differentiation into effector phenotypes. CD3 was rapidly and substantially induced after activation in neutral, but not T2 conditions, potentially contributing to greater division and differentiation in neutral conditions. CD8+ central memory T cells (TCM were less able to enter division upon reactivation in T2 compared with neutral conditions, and were more refractory to modulating IFN-γ and IL-4 production than CD8+ TN. In summary, while activation of TN in T2 conditions can generate T2 cytokine-biased cells, IL-4 expression is weak, T2 bias is lost upon strong restimulation, differentiation, and division

  13. THE MECHANISM OF 5-AMINOURACIL-INDUCED SYNCHRONY OF CELL DIVISION IN VI CIA FABA ROOT MERISTEMS

    Science.gov (United States)

    Prensky, Wolf; Smith, Harold H.

    1965-01-01

    Cessation of mitosis was brought about in Vicia faba roots incubated for 24 hours in the thymine analogue, 5-aminouracil. Recovery of mitotic activity began 8 hours after removal from 5-aminouracil and reached a peak at 15 hours. If colchicine was added 4 hours before the peak of mitoses, up to 80 per cent of all cells accumulated in mitotic division stages. By use of single and double labeling techniques, it was shown that synchrony of cell divisions resulted from depression in the rate of DNA synthesis by 5-aminouracil, which brought about an accumulation of cells in the S phase of the cell cycle. Treatment with 5-aminouracil may have also caused a delay in the rate of exit of cells from the G2 period. It appeared to have no effect on the duration of the G1 period. When roots were removed from 5-aminouracil, DNA synthesis resumed in all cells in the S phase. Although thymidine antagonized the effects of 5-aminouracil, an exogenous supply of it was not necessary for the resumption of DNA synthesis, as shown by incorporation studies with tritiated deoxycytidine. PMID:19866644

  14. Characterization of dependencies between growth and division in budding yeast.

    Science.gov (United States)

    Mayhew, Michael B; Iversen, Edwin S; Hartemink, Alexander J

    2017-02-01

    Cell growth and division are processes vital to the proliferation and development of life. Coordination between these two processes has been recognized for decades in a variety of organisms. In the budding yeast Saccharomyces cerevisiae , this coordination or 'size control' appears as an inverse correlation between cell size and the rate of cell-cycle progression, routinely observed in G 1 prior to cell division commitment. Beyond this point, cells are presumed to complete S/G 2 /M at similar rates and in a size-independent manner. As such, studies of dependence between growth and division have focused on G 1 Moreover, in unicellular organisms, coordination between growth and division has commonly been analysed within the cycle of a single cell without accounting for correlations in growth and division characteristics between cycles of related cells. In a comprehensive analysis of three published time-lapse microscopy datasets, we analyse both intra- and inter-cycle dependencies between growth and division, revisiting assumptions about the coordination between these two processes. Interestingly, we find evidence (i) that S/G 2 /M durations are systematically longer in daughters than in mothers, (ii) of dependencies between S/G 2 /M and size at budding that echo the classical G 1 dependencies, and (iii) in contrast with recent bacterial studies, of negative dependencies between size at birth and size accumulated during the cell cycle. In addition, we develop a novel hierarchical model to uncover inter-cycle dependencies, and we find evidence for such dependencies in cells growing in sugar-poor environments. Our analysis highlights the need for experimentalists and modellers to account for new sources of cell-to-cell variation in growth and division, and our model provides a formal statistical framework for the continued study of dependencies between biological processes. © 2017 The Author(s).

  15. Exploring Middle School Students' Conceptions of the Relationship between Genetic Inheritance and Cell Division

    Science.gov (United States)

    Williams, Michelle; DeBarger, Angela Haydel; Montgomery, Beronda L.; Zhou, Xuechun; Tate, Erika

    2012-01-01

    This study examines students' understanding of the normative connections between key concepts of cell division, including both mitosis and meiosis, and underlying biological principles that are critical for an in-depth understanding of genetic inheritance. Using a structural equation modeling method, we examine middle school students'…

  16. Chemical Technology Division annual technical report, 2001

    International Nuclear Information System (INIS)

    Lewis, D.; Gay, E. C.; Miller, J. C.; Boparai, A. S.

    2002-01-01

    The Chemical Technology Division (CMT) is one of eight engineering research divisions within Argonne National Laboratory, one of the U.S. government's oldest and largest research laboratories. The University of Chicago oversees the laboratory on behalf of the U.S. Department of Energy (DOE). Argonne's mission is to conduct basic scientific research, to operate national scientific facilities, to enhance the nation's energy resources, and to develop better ways to manage environmental problems. Argonne has the further responsibility of strengthening the nation's technology base by developing innovative technology and transferring it to industry. CMT is a diverse early-stage engineering organization, specializing in the treatment of spent nuclear fuel, development of advanced electrochemical power sources, and management of both high- and low-level nuclear wastes. Although this work is often indistinguishable from basic research, our efforts are directed toward the practical devices and processes that are covered by Argonne's mission. Additionally, the Division operates the Analytical Chemistry Laboratory and Environment, Safety, and Health Analytical Chemistry services, which provide a broad range of analytical services to Argonne and other organizations. The Division is multidisciplinary. Its people have formal training as ceramists; physicists; material scientists; electrical, mechanical, chemical, and nuclear engineers; and chemists. They have experience working in academia; urban planning; and the petroleum, aluminum, and automotive industries. Their skills include catalysis, ceramics, electrochemistry, metallurgy, nuclear magnetic resonance spectroscopy, and petroleum refining, as well as the development of nuclear waste forms, batteries, and high-temperature super-conductors. The Division's wide-ranging expertise finds ready application in solving energy and environmental problems. Division personnel are frequently called on by governmental and industrial

  17. How bacterial cell division might cheat turgor pressure - a unified mechanism of septal division in Gram-positive and Gram-negative bacteria.

    Science.gov (United States)

    Erickson, Harold P

    2017-08-01

    An important question for bacterial cell division is how the invaginating septum can overcome the turgor force generated by the high osmolarity of the cytoplasm. I suggest that it may not need to. Several studies in Gram-negative bacteria have shown that the periplasm is isoosmolar with the cytoplasm. Indirect evidence suggests that this is also true for Gram-positive bacteria. In this case the invagination of the septum takes place within the uniformly high osmotic pressure environment, and does not have to fight turgor pressure. A related question is how the V-shaped constriction of Gram-negative bacteria relates to the plate-like septum of Gram-positive bacteria. I collected evidence that Gram-negative bacteria have a latent capability of forming plate-like septa, and present a model in which septal division is the basic mechanism in both Gram-positive and Gram-negative bacteria. © 2017 WILEY Periodicals, Inc.

  18. An experimental and computational framework to build a dynamic protein atlas of human cell division

    OpenAIRE

    Kavur, Marina; Kavur, Marina; Kavur, Marina; Ellenberg, Jan; Peters, Jan-Michael; Ladurner, Rene; Martinic, Marina; Kueblbeck, Moritz; Nijmeijer, Bianca; Wachsmuth, Malte; Koch, Birgit; Walther, Nike; Politi, Antonio; Heriche, Jean-Karim; Hossain, M.

    2017-01-01

    Essential biological functions of human cells, such as division, require the tight coordination of the activity of hundreds of proteins in space and time. While live cell imaging is a powerful tool to study the distribution and dynamics of individual proteins after fluorescence tagging, it has not yet been used to map protein networks due to the lack of systematic and quantitative experimental and computational approaches. Using the cell and nuclear boundaries as landmarks, we generated a 4D ...

  19. ABI domain-containing proteins contribute to surface protein display and cell division in Staphylococcus aureus.

    Science.gov (United States)

    Frankel, Matthew B; Wojcik, Brandon M; DeDent, Andrea C; Missiakas, Dominique M; Schneewind, Olaf

    2010-10-01

    The human pathogen Staphylococcus aureus requires cell wall anchored surface proteins to cause disease. During cell division, surface proteins with YSIRK signal peptides are secreted into the cross-wall, a layer of newly synthesized peptidoglycan between separating daughter cells. The molecular determinants for the trafficking of surface proteins are, however, still unknown. We screened mutants with non-redundant transposon insertions by fluorescence-activated cell sorting for reduced deposition of protein A (SpA) into the staphylococcal envelope. Three mutants, each of which harboured transposon insertions in genes for transmembrane proteins, displayed greatly reduced envelope abundance of SpA and surface proteins with YSIRK signal peptides. Characterization of the corresponding mutations identified three transmembrane proteins with abortive infectivity (ABI) domains, elements first described in lactococci for their role in phage exclusion. Mutations in genes for ABI domain proteins, designated spdA, spdB and spdC (surface protein display), diminish the expression of surface proteins with YSIRK signal peptides, but not of precursor proteins with conventional signal peptides. spdA, spdB and spdC mutants display an increase in the thickness of cross-walls and in the relative abundance of staphylococci with cross-walls, suggesting that spd mutations may represent a possible link between staphylococcal cell division and protein secretion. © 2010 Blackwell Publishing Ltd.

  20. Sporulation-specific cell division defects in ylmE mutants of Streptomyces coelicolor are rescued by additional deletion of ylmD.

    Science.gov (United States)

    Zhang, Le; Willemse, Joost; Hoskisson, Paul A; van Wezel, Gilles P

    2018-05-09

    Cell division during the reproductive phase of the Streptomyces life-cycle requires tight coordination between synchronous formation of multiple septa and DNA segregation. One remarkable difference with most other bacterial systems is that cell division in Streptomyces is positively controlled by the recruitment of FtsZ by SsgB. Here we show that deletion of ylmD (SCO2081) or ylmE (SCO2080), which lie in operon with ftsZ in the dcw cluster of actinomycetes, has major consequences for sporulation-specific cell division in Streptomyces coelicolor. Electron and fluorescence microscopy demonstrated that ylmE mutants have a highly aberrant phenotype with defective septum synthesis, and produce very few spores with low viability and high heat sensitivity. FtsZ-ring formation was also highly disturbed in ylmE mutants. Deletion of ylmD had a far less severe effect on sporulation. Interestingly, the additional deletion of ylmD restored sporulation to the ylmE null mutant. YlmD and YlmE are not part of the divisome, but instead localize diffusely in aerial hyphae, with differential intensity throughout the sporogenic part of the hyphae. Taken together, our work reveals a function for YlmD and YlmE in the control of sporulation-specific cell division in S. coelicolor, whereby the presence of YlmD alone results in major developmental defects.

  1. Sea urchin akt activity is Runx-dependent and required for post-cleavage stage cell division

    KAUST Repository

    Robertson, Anthony J.

    2013-03-25

    In animal development following the initial cleavage stage of embryogenesis, the cell cycle becomes dependent on intercellular signaling and controlled by the genomically encoded ontogenetic program. Runx transcription factors are critical regulators of metazoan developmental signaling, and we have shown that the sea urchin Runx gene runt-1, which is globally expressed during early embryogenesis, functions in support of blastula stage cell proliferation and expression of the mitogenic genes pkc1, cyclinD, and several wnts. To obtain a more comprehensive list of early runt-1 regulatory targets, we screened a Strongylocentrotus purpuratus microarray to identify genes mis-expressed in mid-blastula stage runt-1 morphants. This analysis showed that loss of Runx function perturbs the expression of multiple genes involved in cell division, including the pro-growth and survival kinase Akt (PKB), which is significantly underexpressed in runt-1 morphants. Further genomic analysis revealed that Akt is encoded by two genes in the S. purpuratus genome, akt-1 and akt-2, both of which contain numerous canonical Runx target sequences. The transcripts of both genes accumulate several fold during blastula stage, contingent on runt-1 expression. Inhibiting Akt expression or activity causes blastula stage cell cycle arrest, whereas overexpression of akt-1 mRNA rescues cell proliferation in runt-1 morphants. These results indicate that post-cleavage stage cell division requires Runx-dependent expression of akt.

  2. Sea urchin akt activity is Runx-dependent and required for post-cleavage stage cell division

    KAUST Repository

    Robertson, Anthony J.; Coluccio, Alison; Jensen, Sarah; Rydlizky, Katarina; Coffman, James A.

    2013-01-01

    In animal development following the initial cleavage stage of embryogenesis, the cell cycle becomes dependent on intercellular signaling and controlled by the genomically encoded ontogenetic program. Runx transcription factors are critical regulators of metazoan developmental signaling, and we have shown that the sea urchin Runx gene runt-1, which is globally expressed during early embryogenesis, functions in support of blastula stage cell proliferation and expression of the mitogenic genes pkc1, cyclinD, and several wnts. To obtain a more comprehensive list of early runt-1 regulatory targets, we screened a Strongylocentrotus purpuratus microarray to identify genes mis-expressed in mid-blastula stage runt-1 morphants. This analysis showed that loss of Runx function perturbs the expression of multiple genes involved in cell division, including the pro-growth and survival kinase Akt (PKB), which is significantly underexpressed in runt-1 morphants. Further genomic analysis revealed that Akt is encoded by two genes in the S. purpuratus genome, akt-1 and akt-2, both of which contain numerous canonical Runx target sequences. The transcripts of both genes accumulate several fold during blastula stage, contingent on runt-1 expression. Inhibiting Akt expression or activity causes blastula stage cell cycle arrest, whereas overexpression of akt-1 mRNA rescues cell proliferation in runt-1 morphants. These results indicate that post-cleavage stage cell division requires Runx-dependent expression of akt.

  3. Exposure to Sub-lethal 2,4-Dichlorophenoxyacetic Acid Arrests Cell Division and Alters Cell Surface Properties in Escherichia coli

    Science.gov (United States)

    Bhat, Supriya V.; Kamencic, Belma; Körnig, André; Shahina, Zinnat; Dahms, Tanya E. S.

    2018-01-01

    Escherichia coli is a robust, easily adaptable and culturable bacterium in vitro, and a model bacterium for studying the impact of xenobiotics in the environment. We have used correlative atomic force – laser scanning confocal microscopy (AFM-LSCM) to characterize the mechanisms of cellular response to the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). One of the most extensively used herbicides world-wide, 2,4-D is known to cause hazardous effects in diverse non-target organisms. Sub-lethal concentrations of 2,4-D caused DNA damage in E. coli WM1074 during short exposure periods which increased significantly over time. In response to 2,4-D, FtsZ and FtsA relocalized within seconds, coinciding with the complete inhibition of cell septation and cell elongation. Exposure to 2,4-D also resulted in increased activation of the SOS response. Changes to cell division were accompanied by concomitant changes to surface roughness, elasticity and adhesion in a time-dependent manner. This is the first study describing the mechanistic details of 2,4-D at sub-lethal levels in bacteria. Our study suggests that 2,4-D arrests E. coli cell division within seconds after exposure by disrupting the divisome complex, facilitated by dissipation of membrane potential. Over longer exposures, 2,4-D causes filamentation as a result of an SOS response to oxidative stress induced DNA damage. PMID:29472899

  4. An automated image analysis framework for segmentation and division plane detection of single live Staphylococcus aureus cells which can operate at millisecond sampling time scales using bespoke Slimfield microscopy

    Science.gov (United States)

    Wollman, Adam J. M.; Miller, Helen; Foster, Simon; Leake, Mark C.

    2016-10-01

    Staphylococcus aureus is an important pathogen, giving rise to antimicrobial resistance in cell strains such as Methicillin Resistant S. aureus (MRSA). Here we report an image analysis framework for automated detection and image segmentation of cells in S. aureus cell clusters, and explicit identification of their cell division planes. We use a new combination of several existing analytical tools of image analysis to detect cellular and subcellular morphological features relevant to cell division from millisecond time scale sampled images of live pathogens at a detection precision of single molecules. We demonstrate this approach using a fluorescent reporter GFP fused to the protein EzrA that localises to a mid-cell plane during division and is involved in regulation of cell size and division. This image analysis framework presents a valuable platform from which to study candidate new antimicrobials which target the cell division machinery, but may also have more general application in detecting morphologically complex structures of fluorescently labelled proteins present in clusters of other types of cells.

  5. Functional redundancy of division specific penicillin-binding proteins in Bacillus subtilis.

    Science.gov (United States)

    Sassine, Jad; Xu, Meizhu; Sidiq, Karzan R; Emmins, Robyn; Errington, Jeff; Daniel, Richard A

    2017-10-01

    Bacterial cell division involves the dynamic assembly of a diverse set of proteins that coordinate the invagination of the cell membrane and synthesis of cell wall material to create the new cell poles of the separated daughter cells. Penicillin-binding protein PBP 2B is a key cell division protein in Bacillus subtilis proposed to have a specific catalytic role in septal wall synthesis. Unexpectedly, we find that a catalytically inactive mutant of PBP 2B supports cell division, but in this background the normally dispensable PBP 3 becomes essential. Phenotypic analysis of pbpC mutants (encoding PBP 3) shows that PBP 2B has a crucial structural role in assembly of the division complex, independent of catalysis, and that its biochemical activity in septum formation can be provided by PBP 3. Bioinformatic analysis revealed a close sequence relationship between PBP 3 and Staphylococcus aureus PBP 2A, which is responsible for methicillin resistance. These findings suggest that mechanisms for rescuing cell division when the biochemical activity of PBP 2B is perturbed evolved prior to the clinical use of β-lactams. © 2017 The Authors. Molecular Microbiology published by John Wiley & Sons Ltd.

  6. Robustness of the division symmetry in Escherichia coli and functional consequences of symmetry breaking

    International Nuclear Information System (INIS)

    Gupta, Abhishekh; Lloyd-Price, Jason; Oliveira, Samuel M D; Yli-Harja, Olli; Muthukrishnan, Anantha-Barathi; Ribeiro, Andre S

    2014-01-01

    The morphological symmetry of the division process of Escherichia coli is well-known. Recent studies verified that, in optimal growth conditions, most divisions are symmetric, although there are exceptions. We investigate whether such morphological asymmetries in division introduce functional asymmetries between sister cells, and assess the robustness of the symmetry in division to mild chemical stresses and sub-optimal temperatures. First, we show that the difference in size between daughter cells at birth is positively correlated to the difference between the numbers of fluorescent protein complexes inherited from the parent cell. Next, we show that the degree of symmetry in division observed in optimal conditions is robust to mild acidic shift and to mild oxidative stress, but not to sub-optimal temperatures, in that the variance of the difference between the sizes of sister cells at birth is minimized at 37 °C. This increased variance affects the functionality of the cells in that, at sub-optimal temperatures, larger/smaller cells arising from asymmetric divisions exhibit faster/slower division times than the mean population division time, respectively. On the other hand, cells dividing faster do not do so at the cost of morphological symmetry in division. Finally we show that at suboptimal temperatures the mean distance between the nucleoids increases, explaining the increased variance in division. We conclude that the functionality of E. coli cells is not immune to morphological asymmetries at birth, and that the effectiveness of the mechanism responsible for ensuring the symmetry in division weakens at sub-optimal temperatures. (paper)

  7. Deliberate ROS production and auxin synergistically trigger the asymmetrical division generating the subsidiary cells in Zea mays stomatal complexes.

    Science.gov (United States)

    Livanos, Pantelis; Galatis, Basil; Apostolakos, Panagiotis

    2016-07-01

    Subsidiary cell generation in Poaceae is an outstanding example of local intercellular stimulation. An inductive stimulus emanates from the guard cell mother cells (GMCs) towards their laterally adjacent subsidiary cell mother cells (SMCs) and triggers the asymmetrical division of the latter. Indole-3-acetic acid (IAA) immunolocalization in Zea mays protoderm confirmed that the GMCs function as local sources of auxin and revealed that auxin is polarly accumulated between GMCs and SMCs in a timely-dependent manner. Besides, staining techniques showed that reactive oxygen species (ROS) exhibit a closely similar, also time-dependent, pattern of appearance suggesting ROS implication in subsidiary cell formation. This phenomenon was further investigated by using the specific NADPH-oxidase inhibitor diphenylene iodonium, the ROS scavenger N-acetyl-cysteine, menadione which leads to ROS overproduction, and H2O2. Treatments with diphenylene iodonium, N-acetyl-cysteine, and menadione specifically blocked SMC polarization and asymmetrical division. In contrast, H2O2 promoted the establishment of SMC polarity and subsequently subsidiary cell formation in "younger" protodermal areas. Surprisingly, H2O2 favored the asymmetrical division of the intervening cells of the stomatal rows leading to the creation of extra apical subsidiary cells. Moreover, H2O2 altered IAA localization, whereas synthetic auxin analogue 1-napthaleneacetic acid enhanced ROS accumulation. Combined treatments with ROS modulators along with 1-napthaleneacetic acid or 2,3,5-triiodobenzoic acid, an auxin efflux inhibitor, confirmed the crosstalk between ROS and auxin functioning during subsidiary cell generation. Collectively, our results demonstrate that ROS are critical partners of auxin during development of Z. mays stomatal complexes. The interplay between auxin and ROS seems to be spatially and temporarily regulated.

  8. Loss of CDKC;2 increases both cell division and drought tolerance in Arabidopsis thaliana.

    Science.gov (United States)

    Zhao, Lina; Li, Yaqiong; Xie, Qi; Wu, Yaorong

    2017-09-01

    Drought stress is one of the abiotic stresses that limit plant growth and agricultural productivity. To further understand the mechanism of drought tolerance and identify the genes involved in this process, a genetic screen for altered drought response was conducted in Arabidopsis. One mutant with enhanced drought tolerance was isolated and named Arabidopsis drought tolerance mutant 1 (atdtm1), which has larger lateral organs, prolonged growth duration, increased relative water content and a reduced leaf stomatal density compared with the wild type. The loss of AtDTM1 increases cell division during leaf development. The phenotype is caused by the loss of a T-DNA tagged gene encoding CYCLIN-DEPENDENT KINASE C;2 (CDKC;2), which functions in the regulation of transcription by influencing the phosphorylation status of RNA polymerase II (Pol II). Here, we show that CDKC;2 affects the transcription of downstream genes such as cell cycle genes and genes involved in stomatal development, resulting in altered plant organ size as well as drought tolerance of the plant. These results reveal the crucial role of CDKC;2 in modulating both cell division and the drought response in Arabidopsis. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

  9. The interplay of structural and relational governance in innovation alliances

    NARCIS (Netherlands)

    Garbade, P.J.P.; Omta, S.W.F.; Fortuin, F.T.J.M.

    2016-01-01

    The present paper aims to extend the discussion in the governance literature about whether structural and relational governance mechanisms complement or substitute each other in innovation alliances. Where structural governance mechanisms refer to the division of tasks within the alliance and to

  10. Termination of T cell priming relies on a phase of unresponsiveness promoting disengagement from APCs and T cell division.

    Science.gov (United States)

    Bohineust, Armelle; Garcia, Zacarias; Beuneu, Hélène; Lemaître, Fabrice; Bousso, Philippe

    2018-05-07

    T cells are primed in secondary lymphoid organs by establishing stable interactions with antigen-presenting cells (APCs). However, the cellular mechanisms underlying the termination of T cell priming and the initiation of clonal expansion remain largely unknown. Using intravital imaging, we observed that T cells typically divide without being associated to APCs. Supporting these findings, we demonstrate that recently activated T cells have an intrinsic defect in establishing stable contacts with APCs, a feature that was reflected by a blunted capacity to stop upon T cell receptor (TCR) engagement. T cell unresponsiveness was caused, in part, by a general block in extracellular calcium entry. Forcing TCR signals in activated T cells antagonized cell division, suggesting that T cell hyporesponsiveness acts as a safeguard mechanism against signals detrimental to mitosis. We propose that transient unresponsiveness represents an essential phase of T cell priming that promotes T cell disengagement from APCs and favors effective clonal expansion. © 2018 Bohineust et al.

  11. Fibroblasts Cultured on Nanowires Exhibit Low Motility, Impaired Cell Division, and DNA Damage

    DEFF Research Database (Denmark)

    Persson, H.; Købler, Carsten; Mølhave, Kristian

    2013-01-01

    beam milling and scanning electron microscopy, highly curved but intact nuclear membranes are observed, showing no direct contact between the nanowires and the DNA. The nanowires possibly induce cellular stress and high respiration rates, which trigger the formation of ROS, which in turn results in DNA......Nanowires are commonly used as tools for interfacing living cells, acting as biomolecule-delivery vectors or electrodes. It is generally assumed that the small size of the nanowires ensures a minimal cellular perturbation, yet the effects of nanowires on cell migration and proliferation remain...... largely unknown. Fibroblast behaviour on vertical nanowire arrays is investigated, and it is shown that cell motility and proliferation rate are reduced on nanowires. Fibroblasts cultured on long nanowires exhibit failed cell division, DNA damage, increased ROS content and respiration. Using focused ion...

  12. Division of tongue tie: review of practice through a tertiary paediatric otorhinolaryngology service.

    LENUS (Irish Health Repository)

    Glynn, R W

    2012-10-01

    Recent NICE guidance declared that evidence regarding surgical division of tongue tie was adequate to support the use of the procedure, provided that normal arrangements are in place for consent, audit and clinical governance. This work aimed to carry out a retrospective review of those patients who have previously undergone tongue tie division through a tertiary paediatric otorhinolaryngology service. We further aimed to identify the referral patterns, indications for, and outcomes following, division.

  13. The SPOR Domain, a Widely Conserved Peptidoglycan Binding Domain That Targets Proteins to the Site of Cell Division.

    Science.gov (United States)

    Yahashiri, Atsushi; Jorgenson, Matthew A; Weiss, David S

    2017-07-15

    Sporulation-related repeat (SPOR) domains are small peptidoglycan (PG) binding domains found in thousands of bacterial proteins. The name "SPOR domain" stems from the fact that several early examples came from proteins involved in sporulation, but SPOR domain proteins are quite diverse and contribute to a variety of processes that involve remodeling of the PG sacculus, especially with respect to cell division. SPOR domains target proteins to the division site by binding to regions of PG devoid of stem peptides ("denuded" glycans), which in turn are enriched in septal PG by the intense, localized activity of cell wall amidases involved in daughter cell separation. This targeting mechanism sets SPOR domain proteins apart from most other septal ring proteins, which localize via protein-protein interactions. In addition to SPOR domains, bacteria contain several other PG-binding domains that can exploit features of the cell wall to target proteins to specific subcellular sites. Copyright © 2017 American Society for Microbiology.

  14. Inhibition of Cell Survival by Curcumin Is Associated with Downregulation of Cell Division Cycle 20 (Cdc20) in Pancreatic Cancer Cells.

    Science.gov (United States)

    Zhang, Yu; Xue, Ying-Bo; Li, Hang; Qiu, Dong; Wang, Zhi-Wei; Tan, Shi-Sheng

    2017-02-04

    Pancreatic cancer is one of the most aggressive human tumors in the United States. Curcumin, a polyphenol derived from the Curcuma longa plant, has been reported to exert its antitumor activity in pancreatic cancer. However, the molecular mechanisms of curcumin-mediated tumor suppressive function have not been fully elucidated. In the current study, we explore whether curcumin exhibits its anti-cancer function through inhibition of oncoprotein cell division cycle 20 (Cdc20) in pancreatic cancer cells. We found that curcumin inhibited cell growth, enhanced apoptosis, induced cell cycle arrest and retarded cell invasion in pancreatic cancer cells. Moreover, we observed that curcumin significantly inhibited the expression of Cdc20 in pancreatic cancer cells. Furthermore, our results demonstrated that overexpression of Cdc20 enhanced cell proliferation and invasion, and abrogated the cytotoxic effects induced by curcumin in pancreatic cancer cells. Consistently, downregulation of Cdc20 promoted curcumin-mediated anti-tumor activity. Therefore, our findings indicated that inhibition of Cdc20 by curcumin could be useful for the treatment of pancreatic cancer patients.

  15. Parkin suppresses Drp1-independent mitochondrial division

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Madhuparna, E-mail: mroy17@jhmi.edu; Itoh, Kie, E-mail: kito5@jhmi.edu; Iijima, Miho, E-mail: miijima@jhmi.edu; Sesaki, Hiromi, E-mail: hsesaki@jhmi.edu

    2016-07-01

    The cycle of mitochondrial division and fusion disconnect and reconnect individual mitochondria in cells to remodel this energy-producing organelle. Although dynamin-related protein 1 (Drp1) plays a major role in mitochondrial division in cells, a reduced level of mitochondrial division still persists even in the absence of Drp1. It is unknown how much Drp1-mediated mitochondrial division accounts for the connectivity of mitochondria. The role of a Parkinson’s disease-associated protein—parkin, which biochemically and genetically interacts with Drp1—in mitochondrial connectivity also remains poorly understood. Here, we quantified the number and connectivity of mitochondria using mitochondria-targeted photoactivatable GFP in cells. We show that the loss of Drp1 increases the connectivity of mitochondria by 15-fold in mouse embryonic fibroblasts (MEFs). While a single loss of parkin does not affect the connectivity of mitochondria, the connectivity of mitochondria significantly decreased compared with a single loss of Drp1 when parkin was lost in the absence of Drp1. Furthermore, the loss of parkin decreased the frequency of depolarization of the mitochondrial inner membrane that is caused by increased mitochondrial connectivity in Drp1-knockout MEFs. Therefore, our data suggest that parkin negatively regulates Drp1-indendent mitochondrial division. -- Highlights: •A Drp1-mediated mechanism accounts for ∼95% of mitochondrial division. •Parkin controls the connectivity of mitochondria via a mechanism that is independent of Drp1. •In the absence of Drp1, connected mitochondria transiently depolarize. •The transient depolarization is independent of calcium signaling and uncoupling protein 2.

  16. Parkin suppresses Drp1-independent mitochondrial division

    International Nuclear Information System (INIS)

    Roy, Madhuparna; Itoh, Kie; Iijima, Miho; Sesaki, Hiromi

    2016-01-01

    The cycle of mitochondrial division and fusion disconnect and reconnect individual mitochondria in cells to remodel this energy-producing organelle. Although dynamin-related protein 1 (Drp1) plays a major role in mitochondrial division in cells, a reduced level of mitochondrial division still persists even in the absence of Drp1. It is unknown how much Drp1-mediated mitochondrial division accounts for the connectivity of mitochondria. The role of a Parkinson’s disease-associated protein—parkin, which biochemically and genetically interacts with Drp1—in mitochondrial connectivity also remains poorly understood. Here, we quantified the number and connectivity of mitochondria using mitochondria-targeted photoactivatable GFP in cells. We show that the loss of Drp1 increases the connectivity of mitochondria by 15-fold in mouse embryonic fibroblasts (MEFs). While a single loss of parkin does not affect the connectivity of mitochondria, the connectivity of mitochondria significantly decreased compared with a single loss of Drp1 when parkin was lost in the absence of Drp1. Furthermore, the loss of parkin decreased the frequency of depolarization of the mitochondrial inner membrane that is caused by increased mitochondrial connectivity in Drp1-knockout MEFs. Therefore, our data suggest that parkin negatively regulates Drp1-indendent mitochondrial division. -- Highlights: •A Drp1-mediated mechanism accounts for ∼95% of mitochondrial division. •Parkin controls the connectivity of mitochondria via a mechanism that is independent of Drp1. •In the absence of Drp1, connected mitochondria transiently depolarize. •The transient depolarization is independent of calcium signaling and uncoupling protein 2.

  17. Dynamic single-cell NAD(P)H measurement reveals oscillatory metabolism throughout the E. coli cell division cycle.

    Science.gov (United States)

    Zhang, Zheng; Milias-Argeitis, Andreas; Heinemann, Matthias

    2018-02-01

    Recent work has shown that metabolism between individual bacterial cells in an otherwise isogenetic population can be different. To investigate such heterogeneity, experimental methods to zoom into the metabolism of individual cells are required. To this end, the autofluoresence of the redox cofactors NADH and NADPH offers great potential for single-cell dynamic NAD(P)H measurements. However, NAD(P)H excitation requires UV light, which can cause cell damage. In this work, we developed a method for time-lapse NAD(P)H imaging in single E. coli cells. Our method combines a setup with reduced background emission, UV-enhanced microscopy equipment and optimized exposure settings, overall generating acceptable NAD(P)H signals from single cells, with minimal negative effect on cell growth. Through different experiments, in which we perturb E. coli's redox metabolism, we demonstrated that the acquired fluorescence signal indeed corresponds to NAD(P)H. Using this new method, for the first time, we report that intracellular NAD(P)H levels oscillate along the bacterial cell division cycle. The developed method for dynamic measurement of NAD(P)H in single bacterial cells will be an important tool to zoom into metabolism of individual cells.

  18. Management Data Used to Manage the Defense Logistics Agency Supply Management Division of the Defense Business Operations Fund

    National Research Council Canada - National Science Library

    1994-01-01

    The Defense Logistics Agency Supply Management Division (the Division) of the Defense Business Operations Fund provides supplies and logistics services to DoD Components and other (Government agencies...

  19. Representative Democracy in Australian Local Government

    Directory of Open Access Journals (Sweden)

    Colin Hearfield

    2009-01-01

    Full Text Available In an assessment of representative democracy in Australian local government, this paper considers long-run changes in forms of political representation, methods of vote counting, franchise arrangements, numbers of local government bodies and elected representatives, as well as the thorny question of constitutional recognition. This discussion is set against the background of ongoing tensions between the drive for economic efficiency and the maintenance of political legitimacy, along with more deep-seated divisions emerging from the legal relationship between local and state governments and the resultant problems inherent in local government autonomy versus state intervention.

  20. BioClips of symmetric and asymmetric cell division.

    Science.gov (United States)

    Lu, Fong-Mei; Eliceiri, Kevin W; White, John G

    2007-05-01

    Animations have long been used as tools to illustrate complex processes in such diverse fields as mechanical engineering, astronomy, bacteriology and physics. Animations in biology hold particular educational promise for depicting complex dynamic processes, such as photosynthesis, motility, viral replication and cellular respiration, which cannot be easily explained using static two-dimensional images. However, these animations have often been restrictive in scope, having been created for a specific classroom or research audience. In recent years, a new type of animation has emerged called the BioClip (http://www.bioclips.com) that strives to present science in an interactive multimedia format, which is, at once, informative and entertaining, by combining animations, text descriptions and music in one portable cross-platform document. In the present article, we illustrate the educational value of this new electronic resource by reviewing in depth two BioClips our group has created which describe the processes of symmetric and asymmetric cell division (http://www.wormclassroom.org/cb/bioclip).

  1. 2002 Chemical Engineering Division annual report

    International Nuclear Information System (INIS)

    Lewis, D.; Graziano, D.; Miller, J. F.

    2003-01-01

    The Chemical Engineering Division is one of eight engineering research divisions within Argonne National Laboratory, one of the U.S. government's oldest and largest research laboratories. The University of Chicago oversees the laboratory on behalf of the U.S. Department of Energy (DOE). Argonne's mission is to conduct basic scientific research, to operate national scientific facilities, to enhance the nation's energy resources, and to develop better ways to manage environmental problems. Argonne has the further responsibility of strengthening the nation's technology base by developing innovative technology and transferring it to industry. The Division is a diverse early-stage engineering organization, specializing in the treatment of spent nuclear fuel, development of advanced electrochemical power sources, and management of both high- and low-level nuclear wastes. Although this work is often indistinguishable from basic research, our efforts are directed toward the practical devices and processes that are covered by Argonne's mission. Additionally, the Division operates the Analytical Chemistry Laboratory; Environment, Safety, and Health Analytical Chemistry services; and Dosimetry and Radioprotection services, which provide a broad range of analytical services to Argonne and other organizations. The Division is multidisciplinary. Its people have formal training as ceramists; physicists; material scientists; electrical, mechanical, chemical, and nuclear engineers; and chemists. They have experience working in academia; urban planning; and the petroleum, aluminum, and automotive industries. Their skills include catalysis, ceramics, electrochemistry, metallurgy, nuclear magnetic resonance spectroscopy, and petroleum refining, as well as the development of nuclear waste forms, batteries, and high-temperature superconductors. Our wide-ranging expertise finds ready application in solving energy and environmental problems. Division personnel are frequently called on by

  2. An Aminopropyl Carbazole Derivative Induces Neurogenesis by Increasing Final Cell Division in Neural Stem Cells.

    Science.gov (United States)

    Shin, Jae-Yeon; Kong, Sun-Young; Yoon, Hye Jin; Ann, Jihyae; Lee, Jeewoo; Kim, Hyun-Jung

    2015-07-01

    P7C3 and its derivatives, 1-(3,6-dibromo-9H-carbazol-9-yl)-3-(p-tolylamino)propan-2-ol (1) and N-(3-(3,6-dibromo-9H-carbazol-9-yl)-2-hydroxypropyl)-N-(3-methoxyphenyl)-4-methylbenzenesulfonamide (2), were previously reported to increase neurogenesis in rat neural stem cells (NSCs). Although P7C3 is known to increase neurogenesis by protecting newborn neurons, it is not known whether its derivatives also have protective effects to increase neurogenesis. In the current study, we examined how 1 induces neurogenesis. The treatment of 1 in NSCs increased numbers of cells in the absence of epidermal growth factor (EGF) and fibroblast growth factor 2 (FGF2), while not affecting those in the presence of growth factors. Compound 1 did not induce astrocytogenesis during NSC differentiation. 5-Bromo-2'-deoxyuridine (BrdU) pulsing experiments showed that 1 significantly enhanced BrdU-positive neurons. Taken together, our data suggest that 1 promotes neurogenesis by the induction of final cell division during NSC differentiation.

  3. Multi-isotope imaging mass spectrometry quantifies stem cell division and metabolism.

    Science.gov (United States)

    Steinhauser, Matthew L; Bailey, Andrew P; Senyo, Samuel E; Guillermier, Christelle; Perlstein, Todd S; Gould, Alex P; Lee, Richard T; Lechene, Claude P

    2012-01-15

    Mass spectrometry with stable isotope labels has been seminal in discovering the dynamic state of living matter, but is limited to bulk tissues or cells. We developed multi-isotope imaging mass spectrometry (MIMS) that allowed us to view and measure stable isotope incorporation with submicrometre resolution. Here we apply MIMS to diverse organisms, including Drosophila, mice and humans. We test the 'immortal strand hypothesis', which predicts that during asymmetric stem cell division chromosomes containing older template DNA are segregated to the daughter destined to remain a stem cell, thus insuring lifetime genetic stability. After labelling mice with (15)N-thymidine from gestation until post-natal week 8, we find no (15)N label retention by dividing small intestinal crypt cells after a four-week chase. In adult mice administered (15)N-thymidine pulse-chase, we find that proliferating crypt cells dilute the (15)N label, consistent with random strand segregation. We demonstrate the broad utility of MIMS with proof-of-principle studies of lipid turnover in Drosophila and translation to the human haematopoietic system. These studies show that MIMS provides high-resolution quantification of stable isotope labels that cannot be obtained using other techniques and that is broadly applicable to biological and medical research.

  4. (1) The Relationship of Protein Expression and Cell Division, (2) 3D Imaging of Cells Using Digital Holography, and (3) General Chemistry Enrollment at University of Michigan

    Science.gov (United States)

    Matz, Rebecca L.

    2012-01-01

    Chapter 1: The role of cell division in protein expression is important to understand in order to guide the development of better nonviral gene delivery materials that can transport DNA to the nucleus with high efficiency for a variety of cell types, particularly when nondividing cells are targets of gene therapy. We evaluated the relationship…

  5. LocZ is a new cell division protein involved in proper septum placement in Streptococcus pneumoniae

    Czech Academy of Sciences Publication Activity Database

    Holečková, Nela; Doubravová, Linda; Massidda, Orietta; Molle, Virginie; Buriánková, Karolína; Benada, Oldřich; Kofroňová, Olga; Ulrych, Aleš; Branny, Pavel

    2015-01-01

    Roč. 6, č. 1 (2015), s. 1-13 ISSN 2150-7511 R&D Projects: GA ČR GAP207/12/1568; GA ČR GAP302/12/0256 Institutional support: RVO:61388971 Keywords : cell division * septum placement * Streptococcus pneumoniae Subject RIV: EE - Microbiology, Virology Impact factor: 6.975, year: 2015

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

    DEFF Research Database (Denmark)

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

    2011-01-01

    The cell division cycle and mitosis of intra-erythrocytic (IE) Plasmodium falciparum are poorly understood aspects of parasite development which affect malaria molecular pathogenesis. Specifically, the timing of the multiple gap (G), DNA synthesis (S) and chromosome separation (M) phases of paras......The cell division cycle and mitosis of intra-erythrocytic (IE) Plasmodium falciparum are poorly understood aspects of parasite development which affect malaria molecular pathogenesis. Specifically, the timing of the multiple gap (G), DNA synthesis (S) and chromosome separation (M) phases...... of parasite mitosis are not well defined, nor whether genome divisions are immediately followed by cleavage of the nuclear envelope. Curiously, daughter merozoite numbers do not follow the geometric expansion expected from equal numbers of binary divisions, an outcome difficult to explain using the standard...

  7. SecA is required for membrane targeting of the cell division protein DivIVA in vivo

    Directory of Open Access Journals (Sweden)

    Sven eHalbedel

    2014-02-01

    Full Text Available The conserved protein DivIVA is involved in different morphogenetic processes in Gram-positive bacteria. In Bacillus subtilis, the protein localises to the cell division site and cell poles, and functions as a scaffold for proteins that regulate division site selection, and for proteins that are required for sporulation. To identify other proteins that bind to DivIVA, we performed an in vivo cross-linking experiment. A possible candidate that emerged was the secretion motor ATPase SecA. SecA mutants have been described that inhibit sporulation, and since DivIVA is necessary for sporulation, we examined the localisation of DivIVA in these mutants. Surprisingly, DivIVA was delocalised, suggesting that SecA is required for DivIVA targeting. To further corroborate this, we performed SecA depletion and inhibition experiments, which provided further indications that DivIVA localisation depends on SecA. Cell fractionation experiments showed that SecA is important for binding of DivIVA to the cell membrane. This was unexpected since DivIVA does not contain a signal sequence, and is able to bind to artificial lipid membranes in vitro without support of other proteins. SecA is required for protein secretion and membrane insertion, and therefore its role in DivIVA localisation is likely indirect. Possible alternative roles of SecA in DivIVA folding and/or targeting are discussed.

  8. Stochastic modeling of cell growth with symmetric or asymmetric division

    Science.gov (United States)

    Marantan, Andrew; Amir, Ariel

    2016-07-01

    We consider a class of biologically motivated stochastic processes in which a unicellular organism divides its resources (volume or damaged proteins, in particular) symmetrically or asymmetrically between its progeny. Assuming the final amount of the resource is controlled by a growth policy and subject to additive and multiplicative noise, we derive the recursive integral equation describing the evolution of the resource distribution over subsequent generations and use it to study the properties of stable resource distributions. We find conditions under which a unique stable resource distribution exists and calculate its moments for the class of affine linear growth policies. Moreover, we apply an asymptotic analysis to elucidate the conditions under which the stable distribution (when it exists) has a power-law tail. Finally, we use the results of this asymptotic analysis along with the moment equations to draw a stability phase diagram for the system that reveals the counterintuitive result that asymmetry serves to increase stability while at the same time widening the stable distribution. We also briefly discuss how cells can divide damaged proteins asymmetrically between their progeny as a form of damage control. In the appendixes, motivated by the asymmetric division of cell volume in Saccharomyces cerevisiae, we extend our results to the case wherein mother and daughter cells follow different growth policies.

  9. Cell division and density of symbiotic Chlorella variabilis of the ciliate Paramecium bursaria is controlled by the host's nutritional conditions during early infection process.

    Science.gov (United States)

    Kodama, Yuuki; Fujishima, Masahiro

    2012-10-01

    The association of ciliate Paramecium bursaria with symbiotic Chlorella sp. is a mutualistic symbiosis. However, both the alga-free paramecia and symbiotic algae can still grow independently and can be reinfected experimentally by mixing them. Effects of the host's nutritional conditions against the symbiotic algal cell division and density were examined during early reinfection. Transmission electron microscopy revealed that algal cell division starts 24 h after mixing with alga-free P. bursaria, and that the algal mother cell wall is discarded from the perialgal vacuole membrane, which encloses symbiotic alga. Labelling of the mother cell wall with Calcofluor White Stain, a cell-wall-specific fluorochrome, was used to show whether alga had divided or not. Pulse labelling of alga-free P. bursaria cells with Calcofluor White Stain-stained algae with or without food bacteria for P. bursaria revealed that the fluorescence of Calcofluor White Stain in P. bursaria with bacteria disappeared within 3 days after mixing, significantly faster than without bacteria. Similar results were obtained both under constant light and dark conditions. This report is the first describing that the cell division and density of symbiotic algae of P. bursaria are controlled by the host's nutritional conditions during early infection. © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd.

  10. Chemical Technology Division Annual Report 2000

    International Nuclear Information System (INIS)

    Lewis, D.; Gay, E. C.; Miller, J. F.; Einziger, R. E.; Green, D. W.

    2001-01-01

    The Chemical Technology Division (CMT) is one of eight engineering research divisions within Argonne National Laboratory (ANL), one of the U.S. government's oldest and largest research laboratories. The University of Chicago oversees the laboratory on behalf of the U.S. Department of Energy (DOE). Argonne's mission is to conduct basic scientific research, to operate national scientific facilities, to enhance the nation's energy resources, and to develop better ways to manage environmental problems. Argonne has the further responsibility of strengthening the nation's technology base through developing industrial technology and transferring that technology to industry. The Chemical Technology Division is a diverse early-stage engineering organization, specializing in the treatment of spent nuclear fuel, development of advanced power sources, and management of both high- and low-level nuclear wastes. Although this work is often indistinguishable from basic research, our efforts are directed toward the practical devices and processes that are covered by ANL's mission. Additionally, the Division operates the Analytical Chemistry Laboratory, which provides a broad range of analytical services to ANL and other organizations. The Division is multi-disciplinary. Its people have formal training as ceramists; physicists; material scientists; electrical, mechanical, chemical, and nuclear engineers; and chemists. They have experience working in academia, urban planning, and the petroleum, aluminum, and automotive industries. Their skills include catalysis, ceramics, electrochemistry, metallurgy, nuclear magnetic resonance spectroscopy, and petroleum refining, as well as the development of nuclear waste forms, batteries, and high-temperature superconductors. In this annual report we present an overview of the technical programs together with representative highlights. The report is not intended to be comprehensive or encyclopedic, but to serve as an indication of the condition

  11. Brief Report: Interleukin-17A-Dependent Asymmetric Stem Cell Divisions Are Increased in Human Psoriasis: A Mechanism Underlying Benign Hyperproliferation.

    Science.gov (United States)

    Charruyer, Alexandra; Fong, Stephen; Vitcov, Giselle G; Sklar, Samuel; Tabernik, Leah; Taneja, Monica; Caputo, Melinda; Soeung, Catherine; Yue, Lili; Uchida, Yoshi; Arron, Sarah T; Horton, Karen M; Foster, Robert D; Sano, Shigetoshi; North, Jeffrey P; Ghadially, Ruby

    2017-08-01

    The balance between asymmetric and symmetric stem cell (SC) divisions is key to tissue homeostasis, and dysregulation of this balance has been shown in cancers. We hypothesized that the balance between asymmetric cell divisions (ACDs) and symmetric cell divisions (SCDs) would be dysregulated in the benign hyperproliferation of psoriasis. We found that, while SCDs were increased in squamous cell carcinoma (SCC) (human and murine), ACDs were increased in the benign hyperproliferation of psoriasis (human and murine). Furthermore, while sonic hedgehog (linked to human cancer) and pifithrinα (p53 inhibitor) promoted SCDs, interleukin (IL)-1α and amphiregulin (associated with benign epidermal hyperproliferation) promoted ACDs. While there was dysregulation of the ACD:SCD ratio, no change in SC frequency was detected in epidermis from psoriasis patients, or in human keratinocytes treated with IL-1α or amphiregulin. We investigated the mechanism whereby immune alterations of psoriasis result in ACDs. IL17 inhibitors are effective new therapies for psoriasis. We found that IL17A increased ACDs in human keratinocytes. Additionally, studies in the imiquimod-induced psoriasis-like mouse model revealed that ACDs in psoriasis are IL17A-dependent. In summary, our studies suggest an association between benign hyperproliferation and increased ACDs. This work begins to elucidate the mechanisms by which immune alteration can induce keratinocyte hyperproliferation. Altogether, this work affirms that a finely tuned balance of ACDs and SCDs is important and that manipulating this balance may constitute an effective treatment strategy for hyperproliferative diseases. Stem Cells 2017;35:2001-2007. © 2017 AlphaMed Press.

  12. PASTA repeats of the protein kinase StkP interconnect cell constriction and separation of Streptococcus pneumoniae.

    Science.gov (United States)

    Zucchini, Laure; Mercy, Chryslène; Garcia, Pierre Simon; Cluzel, Caroline; Gueguen-Chaignon, Virginie; Galisson, Frédéric; Freton, Céline; Guiral, Sébastien; Brochier-Armanet, Céline; Gouet, Patrice; Grangeasse, Christophe

    2018-02-01

    Eukaryotic-like serine/threonine kinases (eSTKs) with extracellular PASTA repeats are key membrane regulators of bacterial cell division. How PASTA repeats govern eSTK activation and function remains elusive. Using evolution- and structural-guided approaches combined with cell imaging, we disentangle the role of each PASTA repeat of the eSTK StkP from Streptococcus pneumoniae. While the three membrane-proximal PASTA repeats behave as interchangeable modules required for the activation of StkP independently of cell wall binding, they also control the septal cell wall thickness. In contrast, the fourth and membrane-distal PASTA repeat directs StkP localization at the division septum and encompasses a specific motif that is critical for final cell separation through interaction with the cell wall hydrolase LytB. We propose a model in which the extracellular four-PASTA domain of StkP plays a dual function in interconnecting the phosphorylation of StkP endogenous targets along with septal cell wall remodelling to allow cell division of the pneumococcus.

  13. Cell cycle regulation in human embryonic stem cells: links to adaptation to cell culture.

    Science.gov (United States)

    Barta, Tomas; Dolezalova, Dasa; Holubcova, Zuzana; Hampl, Ales

    2013-03-01

    Cell cycle represents not only a tightly orchestrated mechanism of cell replication and cell division but it also plays an important role in regulation of cell fate decision. Particularly in the context of pluripotent stem cells or multipotent progenitor cells, regulation of cell fate decision is of paramount importance. It has been shown that human embryonic stem cells (hESCs) show unique cell cycle characteristics, such as short doubling time due to abbreviated G1 phase; these properties change with the onset of differentiation. This review summarizes the current understanding of cell cycle regulation in hESCs. We discuss cell cycle properties as well as regulatory machinery governing cell cycle progression of undifferentiated hESCs. Additionally, we provide evidence that long-term culture of hESCs is accompanied by changes in cell cycle properties as well as configuration of several cell cycle regulatory molecules.

  14. Tomato leaf curl Yunnan virus-encoded C4 induces cell division through enhancing stability of Cyclin D 1.1 via impairing NbSKη -mediated phosphorylation in Nicotiana benthamiana

    Science.gov (United States)

    Mei, Yuzhen; Yang, Xiuling; Huang, Changjun

    2018-01-01

    The whitefly-transmitted geminiviruses induce severe developmental abnormalities in plants. Geminivirus-encoded C4 protein functions as one of viral symptom determinants that could induce abnormal cell division. However, the molecular mechanism by which C4 contributes to cell division induction remains unclear. Here we report that tomato leaf curl Yunnan virus (TLCYnV) C4 interacts with a glycogen synthase kinase 3 (GSK3)/SHAGGY-like kinase, designed NbSKη, in Nicotiana benthamiana. Pro32, Asn34 and Thr35 of TLCYnV C4 are critical for its interaction with NbSKη and required for C4-induced typical symptoms. Interestingly, TLCYnV C4 directs NbSKη to the membrane and reduces the nuclear-accumulation of NbSKη. The relocalization of NbSKη impairs phosphorylation dependent degradation on its substrate-Cyclin D1.1 (NbCycD1;1), thereby increasing the accumulation level of NbCycD1;1 and inducing the cell division. Moreover, NbSKη-RNAi, 35S::NbCycD1;1 transgenic N. benthamiana plants have the similar phenotype as 35S::C4 transgenic N. benthamiana plants on callus-like tissue formation resulted from abnormal cell division induction. Thus, this study provides new insights into mechanism of how a viral protein hijacks NbSKη to induce abnormal cell division in plants. PMID:29293689

  15. Insights into the Mechanisms of Chloroplast Division

    Directory of Open Access Journals (Sweden)

    Yamato Yoshida

    2018-03-01

    Full Text Available The endosymbiosis of a free-living cyanobacterium into an ancestral eukaryote led to the evolution of the chloroplast (plastid more than one billion years ago. Given their independent origins, plastid proliferation is restricted to the binary fission of pre-existing plastids within a cell. In the last 25 years, the structure of the supramolecular machinery regulating plastid division has been discovered, and some of its component proteins identified. More recently, isolated plastid-division machineries have been examined to elucidate their structural and mechanistic details. Furthermore, complex studies have revealed how the plastid-division machinery morphologically transforms during plastid division, and which of its component proteins play a critical role in generating the contractile force. Identifying the three-dimensional structures and putative functional domains of the component proteins has given us hints about the mechanisms driving the machinery. Surprisingly, the mechanisms driving plastid division resemble those of mitochondrial division, indicating that these division machineries likely developed from the same evolutionary origin, providing a key insight into how endosymbiotic organelles were established. These findings have opened new avenues of research into organelle proliferation mechanisms and the evolution of organelles.

  16. Mode division multiplexing over 19-cell hollow-core photonic bandgap fibre by employing integrated mode multiplexer

    NARCIS (Netherlands)

    Chen, H.; Uden, van R.G.H.; Okonkwo, C.M.; Jung, Y.; Wheeler, N.V.; Fokoua, E.N.; Baddela, N.; Petrovich, M.N.; Poletti, F.; Richardson, D.J.; Raz, O.; Waardt, de H.; Koonen, A.M.J.

    2014-01-01

    A photonic integrated mode coupler based on silicon-on-insulator is employed for mode division multiplexing (MDM) over a 193 m 19-cell hollow-core photonic bandgap fibre (HC-PBGF) with a -3 dB bandwidth >120 nm. Robust MDM transmissions using LP01 and LP11 modes, and two degenerate LP11 modes (LP11a

  17. Cell division arrest by gamma-irradiation in photoautotrophic suspension culture of Euphorbia characias: maintenance of photosynthetic capacity and overaccumulation of sucrose

    International Nuclear Information System (INIS)

    Chagvardieff, P.; Dimon, B.; Carrier, P.; Triantaphylides, C.

    1989-01-01

    Gamma-irradiation (250 Gy) applied to photoautotrophic cell suspensions of Euphorbia characias L. in the exponential growth phase led to the arrest of cell division and to a subsequent overaccumulation of sucrose and dry matter. From the fourth day of culture, the chlorophyll content and gross photosynthesis were not depressed by gamma-treatment nor by sugar accumulation. In both cultures, no difference was observed between oxygen uptake in the light at CO 2 saturating concentration and in the dark, suggesting that no change in energy-dissipative reactions took place after irradiation. A slight increase in oxygen uptake in both light and dark was observed in irradiated cells during the first four days. However, in the absence of limiting factors, the photosynthetic capacities of the dividing and irradiated non-dividing photoautotrophic cells were identical but higher than that of the non-dividing cells in the stationary growth phase. This suggests that gamma-irradiation arrests cell division by a mechanism different to that occurring in stationary-phase cultures. This may be of value in investigating the metabolism of secondary products. (author)

  18. Site-directed fluorescence labeling reveals a revised N-terminal membrane topology and functional periplasmic residues in the Escherichia coli cell division protein FtsK.

    Science.gov (United States)

    Berezuk, Alison M; Goodyear, Mara; Khursigara, Cezar M

    2014-08-22

    In Escherichia coli, FtsK is a large integral membrane protein that coordinates chromosome segregation and cell division. The N-terminal domain of FtsK (FtsKN) is essential for division, and the C terminus (FtsKC) is a well characterized DNA translocase. Although the function of FtsKN is unknown, it is suggested that FtsK acts as a checkpoint to ensure DNA is properly segregated before septation. This may occur through modulation of protein interactions between FtsKN and other division proteins in both the periplasm and cytoplasm; thus, a clear understanding of how FtsKN is positioned in the membrane is required to characterize these interactions. The membrane topology of FtsKN was initially determined using site-directed reporter fusions; however, questions regarding this topology persist. Here, we report a revised membrane topology generated by site-directed fluorescence labeling. The revised topology confirms the presence of four transmembrane segments and reveals a newly identified periplasmic loop between the third and fourth transmembrane domains. Within this loop, four residues were identified that, when mutated, resulted in the appearance of cellular voids. High resolution transmission electron microscopy of these voids showed asymmetric division of the cytoplasm in the absence of outer membrane invagination or visible cell wall ingrowth. This uncoupling reveals a novel role for FtsK in linking cell envelope septation events and yields further evidence for FtsK as a critical checkpoint of cell division. The revised topology of FtsKN also provides an important platform for future studies on essential interactions required for this process. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  19. A Report on the Survey of Public Relations Division/AEJ Members on Licensing Public Relations Practitioners.

    Science.gov (United States)

    Tennant, Frank A.

    The licensing of public relations practitioners by government has long been controversial. A survey was conducted of members of the public relations division of the Association for Education in Journalism under the auspices of the division's committee on professional freedom and responsibility. One-hundred and sixty-one questionnaires were mailed…

  20. C. elegans GATA factors EGL-18 and ELT-6 function downstream of Wnt signaling to maintain the progenitor fate during larval asymmetric divisions of the seam cells.

    Science.gov (United States)

    Gorrepati, Lakshmi; Thompson, Kenneth W; Eisenmann, David M

    2013-05-01

    The C. elegans seam cells are lateral epithelial cells arrayed in a single line from anterior to posterior that divide in an asymmetric, stem cell-like manner during larval development. These asymmetric divisions are regulated by Wnt signaling; in most divisions, the posterior daughter in which the Wnt pathway is activated maintains the progenitor seam fate, while the anterior daughter in which the Wnt pathway is not activated adopts a differentiated hypodermal fate. Using mRNA tagging and microarray analysis, we identified the functionally redundant GATA factor genes egl-18 and elt-6 as Wnt pathway targets in the larval seam cells. EGL-18 and ELT-6 have previously been shown to be required for initial seam cell specification in the embryo. We show that in larval seam cell asymmetric divisions, EGL-18 is expressed strongly in the posterior seam-fated daughter. egl-18 and elt-6 are necessary for larval seam cell specification, and for hypodermal to seam cell fate transformations induced by ectopic Wnt pathway overactivation. The TCF homolog POP-1 binds a site in the egl-18 promoter in vitro, and this site is necessary for robust seam cell expression in vivo. Finally, larval overexpression of EGL-18 is sufficient to drive expression of a seam marker in other hypodermal cells in wild-type animals, and in anterior hypodermal-fated daughters in a Wnt pathway-sensitized background. These data suggest that two GATA factors that are required for seam cell specification in the embryo independently of Wnt signaling are reused downstream of Wnt signaling to maintain the progenitor fate during stem cell-like divisions in larval development.

  1. Nuclear and cell division in Bacillus subtilis. Antibiotic-induced morphological changes

    NARCIS (Netherlands)

    van Iterson, W.; Aten, J. A.

    1976-01-01

    Incubation of Bacillus subtilis after outgrowth from spores in the presence of four different antibiotics in two different concentrations, showed that septation can occur without termination of nuclear division. Septation is then only partially uncoupled from the normal division cycle. Observations

  2. Does cadastral division of area-based ecosystem services obstruct comprehensive management?

    DEFF Research Database (Denmark)

    Vejre, H.; Vesterager, J. P.; Andersen, P. S.

    2015-01-01

    Management of ecological entities in agricultural landscapes is often challenged by a complex ownership structure governed by a cadastral system dictated by agricultural interests and historical land use practices. The cadastral division is suspected to obstruct the deliverance of ecosystem servi...

  3. Composition and Dynamics of the Nucleolinus, a Link between the Nucleolus and Cell Division Apparatus in Surf Clam (Spisula) Oocytes*

    Science.gov (United States)

    Alliegro, Mark C.; Hartson, Steven; Alliegro, Mary Anne

    2012-01-01

    The nucleolinus is a little-known cellular structure, discovered over 150 years ago (Agassiz, L. (1857) Contributions to the Natural History of the United States of America, First Monograph, Part IIL, Little, Brown and Co., Boston) and thought by some investigators in the late 19th to mid-20th century to function in the formation of the centrosomes or spindle. A role for the nucleolinus in formation of the cell division apparatus has recently been confirmed in oocytes of the surf clam, Spisula solidissima (Alliegro, M. A., Henry, J. J., and Alliegro, M. C. (2010) Proc. Natl. Acad. Sci. U.S.A. 107, 13718–13723). However, we know so little about the composition and dynamics of this compartment, it is difficult to construct mechanistic hypotheses or even to be sure that prior reports were describing analogous structures in the cells of mammals, amphibians, plants, and other organisms where it was observed. Surf clam oocytes are an attractive model to approach this problem because the nucleolinus is easily visible by light microscopy, making it accessible by laser microsurgery as well as isolation by common cell fractionation techniques. In this report, we analyze the macromolecular composition of isolated Spisula nucleolini and examine the relationship of this structure to the nucleolus and cell division apparatus. Analysis of nucleolinar RNA and protein revealed a set of molecules that overlaps with but is nevertheless distinct from the nucleolus. The proteins identified were primarily ones involved in nucleic acid metabolism and cell cycle regulation. Monoclonal antibodies generated against isolated nucleolini revealed centrosomal forerunners in the oocyte cytoplasm. Finally, induction of damage to the nucleolinus by laser microsurgery altered the trafficking of α- and γ-tubulin after fertilization. These observations strongly support a role for the nucleolinus in cell division and represent our first clues regarding mechanism. PMID:22219192

  4. Composition and dynamics of the nucleolinus, a link between the nucleolus and cell division apparatus in surf clam (Spisula) oocytes.

    Science.gov (United States)

    Alliegro, Mark C; Hartson, Steven; Alliegro, Mary Anne

    2012-02-24

    The nucleolinus is a little-known cellular structure, discovered over 150 years ago (Agassiz, L. (1857) Contributions to the Natural History of the United States of America, First Monograph, Part IIL, Little, Brown and Co., Boston) and thought by some investigators in the late 19th to mid-20th century to function in the formation of the centrosomes or spindle. A role for the nucleolinus in formation of the cell division apparatus has recently been confirmed in oocytes of the surf clam, Spisula solidissima (Alliegro, M. A., Henry, J. J., and Alliegro, M. C. (2010) Proc. Natl. Acad. Sci. U.S.A. 107, 13718-13723). However, we know so little about the composition and dynamics of this compartment, it is difficult to construct mechanistic hypotheses or even to be sure that prior reports were describing analogous structures in the cells of mammals, amphibians, plants, and other organisms where it was observed. Surf clam oocytes are an attractive model to approach this problem because the nucleolinus is easily visible by light microscopy, making it accessible by laser microsurgery as well as isolation by common cell fractionation techniques. In this report, we analyze the macromolecular composition of isolated Spisula nucleolini and examine the relationship of this structure to the nucleolus and cell division apparatus. Analysis of nucleolinar RNA and protein revealed a set of molecules that overlaps with but is nevertheless distinct from the nucleolus. The proteins identified were primarily ones involved in nucleic acid metabolism and cell cycle regulation. Monoclonal antibodies generated against isolated nucleolini revealed centrosomal forerunners in the oocyte cytoplasm. Finally, induction of damage to the nucleolinus by laser microsurgery altered the trafficking of α- and γ-tubulin after fertilization. These observations strongly support a role for the nucleolinus in cell division and represent our first clues regarding mechanism.

  5. Emp is a component of the nuclear matrix of mammalian cells and undergoes dynamic rearrangements during cell division

    International Nuclear Information System (INIS)

    Bala, Shashi; Kumar, Ajay; Soni, Shivani; Sinha, Sudha; Hanspal, Manjit

    2006-01-01

    Emp, originally detected in erythroblastic islands, is expressed in numerous cell types and tissues suggesting a functionality not limited to hematopoiesis. To study the function of Emp in non-hematopoietic cells, an epitope-tagged recombinant human Emp was expressed in HEK cells. Preliminary studies revealed that Emp partitioned into both the nuclear and Triton X-100-insoluble cytoskeletal fractions in approximately a 4:1 ratio. In this study, we report investigations of Emp in the nucleus. Sequential extractions of interphase nuclei showed that recombinant Emp was present predominantly in the nuclear matrix. Immunofluorescence microscopy showed that Emp was present in typical nuclear speckles enriched with the spliceosome assembly factor SC35 and partially co-localized with actin staining. Coimmunoprecipitation and GST-pull-down assays confirmed the apparent close association of Emp with nuclear actin. During mitosis, Emp was detected at the mitotic spindle/spindle poles, as well as in the contractile ring during cytokinesis. These results suggest that Emp undergoes dynamic rearrangements within the nuclear architecture that are correlated with cell division

  6. Asymmetric T lymphocyte division in the initiation of adaptive immune responses.

    Science.gov (United States)

    Chang, John T; Palanivel, Vikram R; Kinjyo, Ichiko; Schambach, Felix; Intlekofer, Andrew M; Banerjee, Arnob; Longworth, Sarah A; Vinup, Kristine E; Mrass, Paul; Oliaro, Jane; Killeen, Nigel; Orange, Jordan S; Russell, Sarah M; Weninger, Wolfgang; Reiner, Steven L

    2007-03-23

    A hallmark of mammalian immunity is the heterogeneity of cell fate that exists among pathogen-experienced lymphocytes. We show that a dividing T lymphocyte initially responding to a microbe exhibits unequal partitioning of proteins that mediate signaling, cell fate specification, and asymmetric cell division. Asymmetric segregation of determinants appears to be coordinated by prolonged interaction between the T cell and its antigen-presenting cell before division. Additionally, the first two daughter T cells displayed phenotypic and functional indicators of being differentially fated toward effector and memory lineages. These results suggest a mechanism by which a single lymphocyte can apportion diverse cell fates necessary for adaptive immunity.

  7. Targeting the Wolbachia cell division protein FtsZ as a new approach for antifilarial therapy.

    Directory of Open Access Journals (Sweden)

    Zhiru Li

    2011-11-01

    Full Text Available The use of antibiotics targeting the obligate bacterial endosymbiont Wolbachia of filarial parasites has been validated as an approach for controlling filarial infection in animals and humans. Availability of genomic sequences for the Wolbachia (wBm present in the human filarial parasite Brugia malayi has enabled genome-wide searching for new potential drug targets. In the present study, we investigated the cell division machinery of wBm and determined that it possesses the essential cell division gene ftsZ which was expressed in all developmental stages of B. malayi examined. FtsZ is a GTPase thereby making the protein an attractive Wolbachia drug target. We described the molecular characterization and catalytic properties of Wolbachia FtsZ. We also demonstrated that the GTPase activity was inhibited by the natural product, berberine, and small molecule inhibitors identified from a high-throughput screen. Furthermore, berberine was also effective in reducing motility and reproduction in B. malayi parasites in vitro. Our results should facilitate the discovery of selective inhibitors of FtsZ as a novel anti-symbiotic approach for controlling filarial infection. NOTE: The nucleotide sequences reported in this paper are available in GenBank™ Data Bank under the accession number wAlB-FtsZ (JN616286.

  8. Division of Labor

    KAUST Repository

    Oke, Muse; Zaher, Manal S.; Hamdan, Samir

    2014-01-01

    The first assignment of DNA polymerases at the eukaryotic replication fork was possible after the in vitro reconstitution of the simian virus 40 (SV40) replication system. In this system, DNA polymerase α (Pol α) provides both leading and lagging strands with RNA-DNA primers that are extended by DNA polymerase δ (Pol δ). Extrapolating the architecture of the replication fork from the SV40 model system to an actual eukaryotic cell has been challenged by the discovery of a third DNA polymerase in Saccharomyces cerevisiae, DNA polymerase ε (Pol ε). A division of labor has been proposed for the eukaryotic replication fork whereby Pol ε replicates the leading strand and Pol δ replicates the lagging strand. However, an alternative model of unequal division of labor in which Pol δ can still participate in leading-strand synthesis is plausible.

  9. Division of Labor

    KAUST Repository

    Oke, Muse

    2014-09-12

    The first assignment of DNA polymerases at the eukaryotic replication fork was possible after the in vitro reconstitution of the simian virus 40 (SV40) replication system. In this system, DNA polymerase α (Pol α) provides both leading and lagging strands with RNA-DNA primers that are extended by DNA polymerase δ (Pol δ). Extrapolating the architecture of the replication fork from the SV40 model system to an actual eukaryotic cell has been challenged by the discovery of a third DNA polymerase in Saccharomyces cerevisiae, DNA polymerase ε (Pol ε). A division of labor has been proposed for the eukaryotic replication fork whereby Pol ε replicates the leading strand and Pol δ replicates the lagging strand. However, an alternative model of unequal division of labor in which Pol δ can still participate in leading-strand synthesis is plausible.

  10. A Resistance-Nodulation-Cell Division Family Xenobiotic Efflux Pump in an Obligate Anaerobe, Porphyromonas gingivalis

    OpenAIRE

    Ikeda, Takeshi; Yoshimura, Fuminobu

    2002-01-01

    Porphyromonas gingivalis, a gram-negative obligate anaerobe, contains two homologs of an Escherichia coli resistance-nodulation-cell division-type multidrug exporter gene, acrB, in putative operons, together with homologs of membrane fusion protein gene acrA and outer membrane channel gene tolC. MIC determination and accumulation assays with mutants with disruptions of one or more genes showed that one cluster, named xepCAB, pumped out multiple agents including rifampin, puromycin, and ethidi...

  11. Deficiency of RgpG Causes Major Defects in Cell Division and Biofilm Formation, and Deficiency of LytR-CpsA-Psr Family Proteins Leads to Accumulation of Cell Wall Antigens in Culture Medium by Streptococcus mutans.

    Science.gov (United States)

    De, Arpan; Liao, Sumei; Bitoun, Jacob P; Roth, Randy; Beatty, Wandy L; Wu, Hui; Wen, Zezhang T

    2017-09-01

    Streptococcus mutans is known to possess rhamnose-glucose polysaccharide (RGP), a major cell wall antigen. S. mutans strains deficient in rgpG , encoding the first enzyme of the RGP biosynthesis pathway, were constructed by allelic exchange. The rgpG deficiency had no effect on growth rate but caused major defects in cell division and altered cell morphology. Unlike the coccoid wild type, the rgpG mutant existed primarily in chains of swollen, "squarish" dividing cells. Deficiency of rgpG also causes significant reduction in biofilm formation ( P cell envelope biogenesis, were constructed using the rgpG mutant. There were no major differences in growth rates between the wild-type strain and the rgpG brpA and rgpG psr double mutants, but the growth rate of the rgpG brpA psr triple mutant was reduced drastically ( P cells with multiple asymmetric septa. When analyzed by immunoblotting, the rgpG mutant displayed major reductions in cell wall antigens compared to the wild type, while little or no signal was detected with the double and triple mutants and the brpA and psr single mutants. These results suggest that RgpG in S. mutans plays a critical role in cell division and biofilm formation and that BrpA and Psr may be responsible for attachment of cell wall antigens to the cell envelope. IMPORTANCE Streptococcus mutans , a major etiological agent of human dental caries, produces rhamnose-glucose polysaccharide (RGP) as the major cell wall antigen. This study provides direct evidence that deficiency of RgpG, the first enzyme of the RGP biosynthesis pathway, caused major defects in cell division and morphology and reduced biofilm formation by S. mutans , indicative of a significant role of RGP in cell division and biofilm formation in S. mutans These results are novel not only in S. mutans , but also other streptococci that produce RGP. This study also shows that the LytR-CpsA-Psr family proteins BrpA and Psr in S. mutans are involved in attachment of RGP and probably

  12. Serine/Threonine Protein Phosphatase PstP of Mycobacterium tuberculosis Is Necessary for Accurate Cell Division and Survival of Pathogen*

    Science.gov (United States)

    Sharma, Aditya K.; Arora, Divya; Singh, Lalit K.; Gangwal, Aakriti; Sajid, Andaleeb; Molle, Virginie; Singh, Yogendra; Nandicoori, Vinay Kumar

    2016-01-01

    Protein phosphatases play vital roles in phosphorylation-mediated cellular signaling. Although there are 11 serine/threonine protein kinases in Mycobacterium tuberculosis, only one serine/threonine phosphatase, PstP, has been identified. Although PstP has been biochemically characterized and multiple in vitro substrates have been identified, its physiological role has not yet been elucidated. In this study, we have investigated the impact of PstP on cell growth and survival of the pathogen in the host. Overexpression of PstP led to elongated cells and partially compromised survival. We find that depletion of PstP is detrimental to cell survival, eventually leading to cell death. PstP depletion results in elongated multiseptate cells, suggesting a role for PstP in regulating cell division events. Complementation experiments performed with PstP deletion mutants revealed marginally compromised survival, suggesting that all of the domains, including the extracellular domain, are necessary for complete rescue. On the other hand, the catalytic activity of PstP is absolutely essential for the in vitro growth. Mice infection experiments establish a definitive role for PstP in pathogen survival within the host. Depletion of PstP from established infections causes pathogen clearance, indicating that the continued presence of PstP is necessary for pathogen survival. Taken together, our data suggest an important role for PstP in establishing and maintaining infection, possibly via the modulation of cell division events. PMID:27758870

  13. Can complex cellular processes be governed by simple linear rules?

    Science.gov (United States)

    Selvarajoo, Kumar; Tomita, Masaru; Tsuchiya, Masa

    2009-02-01

    Complex living systems have shown remarkably well-orchestrated, self-organized, robust, and stable behavior under a wide range of perturbations. However, despite the recent generation of high-throughput experimental datasets, basic cellular processes such as division, differentiation, and apoptosis still remain elusive. One of the key reasons is the lack of understanding of the governing principles of complex living systems. Here, we have reviewed the success of perturbation-response approaches, where without the requirement of detailed in vivo physiological parameters, the analysis of temporal concentration or activation response unravels biological network features such as causal relationships of reactant species, regulatory motifs, etc. Our review shows that simple linear rules govern the response behavior of biological networks in an ensemble of cells. It is daunting to know why such simplicity could hold in a complex heterogeneous environment. Provided physical reasons can be explained for these phenomena, major advancement in the understanding of basic cellular processes could be achieved.

  14. Behavior of centrosomes during fertilization and cell division in mouse oocytes and in sea urchin eggs

    Science.gov (United States)

    Schatten, Heide; Schatten, Gerald; Balczon, Ron; Simerly, Calvin; Mazia, Daniel

    1986-01-01

    The behavior of centrosomes during the stages of fertilization and cell division in mouse oocytes and in sea urchin eggs was monitored in an immunofluorescence microscope, using autoimmune centrosomal antiserum derived from a patient with scleroderma to label the centrosomal material. These observations showed that centrosomes reproduce during the interphase and aggregate and separate during cell mitosis. Results supported the hypothesis of Mazia (1984), who proposed that centrosomes are 'flexible bodies'. It was also found that, while the sea urchin centrosomes are paternally inherited as was initially proposed by Bovery (1904), the mouse centrosomes are of maternal origin.

  15. Division delay after low x-ray doses and treatment with cyclohexionide

    International Nuclear Information System (INIS)

    Schneiderman, M.H.; Braby, L.A.; Roesch, W.C.

    1977-01-01

    Radiation-induced division delay of Chinese hamster ovary cells located in G 2 , and in G 2 between the cycloheximide and x-ray transition points, was measured by the mitotic cell selection technique. The mitotic yield (number of mitotic cells after treatment expressed as a fraction of the control) decreased with increasing radiation dose (4.5 to 34 rad). However, either because some cells were not delayed or because delayed cells recovered rapidly, the mitotic yield did not fall to zero. When cycloheximide was combined with radiation to prevent repair of the radiation damage, only cells which were past the cycloheximide transition point and not delayed by the radiation were selected. The location of the transition points determined from the combined drug plus low-dose radiation (4.5 to 34 rad) experiments indicate a dose-dependent relationship, with more cells delayed as the dose was increased. In addition, the transition point for cells treated with cycloheximide plus 150 rad of x rays was closer to division than the 150 rad of x rays alone. These results are discussed in light of a recent model for radiation-induced division delay proposed by Dewey and Highfield

  16. Transfer of unstable chromosomal aberrations in human peripheral lymphocytes at cell division and their significance for the aberration frequency

    International Nuclear Information System (INIS)

    Stephan, G.; Chang Tsangpi.

    1986-04-01

    In 48 h cultures, the fraction of human lymphocytes in 2nd mitosis was found to be between 0 and 42.5% (mean value 8.7%). The X-ray exposure from irradiating with 2 Gy resulted in a cell cycle delay which varied from donor to donor. A loss of nearly 50% of dicentric chromosomes and acentric fragments from unstable chromosomes occurred at cell division, while centric rings were not impeded. When dicentric chromosomes, or acentric fragments are found in 2nd mitosis, they show a characteristic differential staining, which means that chromatides at cell division fall free and are replicated in daughter cells. When plotting dose effect curves of dicentric chromosomes, up to 20% of 2nd mitosis fractions have little influence on the aberration rate. This may be additionally verified as part of the 'biological dosimetry' in a person with 24% of 2nd mitosis. When the rates of dicentric chromosomes exclusively evaluated from 1st mitosis after irradiation with 2.0 Gy were related to the donors age, no age-dependent sensitivity to radiation could be observed. Aberration rates which deviate from person to person are comparable to the results achieved by conventional staining methods. (orig./MG) [de

  17. Determining the control networks regulating stem cell lineages in colonic crypts

    OpenAIRE

    Yang, J; Axelrod, DE; Komarova, NL

    2017-01-01

    The question of stem cell control is at the center of our understanding of tissue functioning, both in healthy and cancerous conditions. It is well accepted that cellular fate decisions (such as divisions, differentiation, apoptosis) are orchestrated by a network of regulatory signals emitted by different cell populations in the lineage and the surrounding tissue. The exact regulatory network that governs stem cell lineages in a given tissue is usually unknown. Here we propose an algorithm to...

  18. Chemical Technology Division annual technical report, 2001

    International Nuclear Information System (INIS)

    Lewis, D.; Gay, E. C.; Miller, J. C.; Boparai, A. S.

    2002-01-01

    The Chemical Technology Division (CMT) is one of eight engineering research divisions within Argonne National Laboratory, one of the U.S. government's oldest and largest research laboratories. The University of Chicago oversees the laboratory on behalf of the U.S. Department of Energy (DOE). Argonne's mission is to conduct basic scientific research, to operate national scientific facilities, to enhance the nation's energy resources, and to develop better ways to manage environmental problems. Argonne has the further responsibility of strengthening the nation's technology base by developing innovative technology and transferring it to industry. CMT is a diverse early-stage engineering organization, specializing in the treatment of spent nuclear fuel, development of advanced electrochemical power sources, and management of both high- and low-level nuclear wastes. Although this work is often indistinguishable from basic research, our efforts are directed toward the practical devices and processes that are covered by Argonne's mission. Additionally, the Division operates the Analytical Chemistry Laboratory and Environment, Safety, and Health Analytical Chemistry services, which provide a broad range of analytical services to Argonne and other organizations. The Division is multidisciplinary. Its people have formal training as ceramists; physicists; material scientists; electrical, mechanical, chemical, and nuclear engineers; and chemists. They have experience working in academia; urban planning; and the petroleum, aluminum, and automotive industries. Their skills include catalysis, ceramics, electrochemistry, metallurgy, nuclear magnetic resonance spectroscopy, and petroleum refining, as well as the development of nuclear waste forms, batteries, and high-temperature superconductors

  19. Structural and functional characterizations of SsgB, a conserved activator of developmental cell division in morphologically complex actinomycetes.

    Science.gov (United States)

    Xu, Qingping; Traag, Bjørn A; Willemse, Joost; McMullan, Daniel; Miller, Mitchell D; Elsliger, Marc-André; Abdubek, Polat; Astakhova, Tamara; Axelrod, Herbert L; Bakolitsa, Constantina; Carlton, Dennis; Chen, Connie; Chiu, Hsiu-Ju; Chruszcz, Maksymilian; Clayton, Thomas; Das, Debanu; Deller, Marc C; Duan, Lian; Ellrott, Kyle; Ernst, Dustin; Farr, Carol L; Feuerhelm, Julie; Grant, Joanna C; Grzechnik, Anna; Grzechnik, Slawomir K; Han, Gye Won; Jaroszewski, Lukasz; Jin, Kevin K; Klock, Heath E; Knuth, Mark W; Kozbial, Piotr; Krishna, S Sri; Kumar, Abhinav; Marciano, David; Minor, Wladek; Mommaas, A Mieke; Morse, Andrew T; Nigoghossian, Edward; Nopakun, Amanda; Okach, Linda; Oommachen, Silvya; Paulsen, Jessica; Puckett, Christina; Reyes, Ron; Rife, Christopher L; Sefcovic, Natasha; Tien, Henry J; Trame, Christine B; van den Bedem, Henry; Wang, Shuren; Weekes, Dana; Hodgson, Keith O; Wooley, John; Deacon, Ashley M; Godzik, Adam; Lesley, Scott A; Wilson, Ian A; van Wezel, Gilles P

    2009-09-11

    SsgA-like proteins (SALPs) are a family of homologous cell division-related proteins that occur exclusively in morphologically complex actinomycetes. We show that SsgB, a subfamily of SALPs, is the archetypal SALP that is functionally conserved in all sporulating actinomycetes. Sporulation-specific cell division of Streptomyces coelicolor ssgB mutants is restored by introduction of distant ssgB orthologues from other actinomycetes. Interestingly, the number of septa (and spores) of the complemented null mutants is dictated by the specific ssgB orthologue that is expressed. The crystal structure of the SsgB from Thermobifida fusca was determined at 2.6 A resolution and represents the first structure for this family. The structure revealed similarities to a class of eukaryotic "whirly" single-stranded DNA/RNA-binding proteins. However, the electro-negative surface of the SALPs suggests that neither SsgB nor any of the other SALPs are likely to interact with nucleotide substrates. Instead, we show that a conserved hydrophobic surface is likely to be important for SALP function and suggest that proteins are the likely binding partners.

  20. Structural and Functional Characterizations of SsgB, a Conserved Activator of Developmental Cell Division in Morphologically Complex Actinomycetes*

    Science.gov (United States)

    Xu, Qingping; Traag, Bjørn A.; Willemse, Joost; McMullan, Daniel; Miller, Mitchell D.; Elsliger, Marc-André; Abdubek, Polat; Astakhova, Tamara; Axelrod, Herbert L.; Bakolitsa, Constantina; Carlton, Dennis; Chen, Connie; Chiu, Hsiu-Ju; Chruszcz, Maksymilian; Clayton, Thomas; Das, Debanu; Deller, Marc C.; Duan, Lian; Ellrott, Kyle; Ernst, Dustin; Farr, Carol L.; Feuerhelm, Julie; Grant, Joanna C.; Grzechnik, Anna; Grzechnik, Slawomir K.; Han, Gye Won; Jaroszewski, Lukasz; Jin, Kevin K.; Klock, Heath E.; Knuth, Mark W.; Kozbial, Piotr; Krishna, S. Sri; Kumar, Abhinav; Marciano, David; Minor, Wladek; Mommaas, A. Mieke; Morse, Andrew T.; Nigoghossian, Edward; Nopakun, Amanda; Okach, Linda; Oommachen, Silvya; Paulsen, Jessica; Puckett, Christina; Reyes, Ron; Rife, Christopher L.; Sefcovic, Natasha; Tien, Henry J.; Trame, Christine B.; van den Bedem, Henry; Wang, Shuren; Weekes, Dana; Hodgson, Keith O.; Wooley, John; Deacon, Ashley M.; Godzik, Adam; Lesley, Scott A.; Wilson, Ian A.; van Wezel, Gilles P.

    2009-01-01

    SsgA-like proteins (SALPs) are a family of homologous cell division-related proteins that occur exclusively in morphologically complex actinomycetes. We show that SsgB, a subfamily of SALPs, is the archetypal SALP that is functionally conserved in all sporulating actinomycetes. Sporulation-specific cell division of Streptomyces coelicolor ssgB mutants is restored by introduction of distant ssgB orthologues from other actinomycetes. Interestingly, the number of septa (and spores) of the complemented null mutants is dictated by the specific ssgB orthologue that is expressed. The crystal structure of the SsgB from Thermobifida fusca was determined at 2.6 Å resolution and represents the first structure for this family. The structure revealed similarities to a class of eukaryotic “whirly” single-stranded DNA/RNA-binding proteins. However, the electro-negative surface of the SALPs suggests that neither SsgB nor any of the other SALPs are likely to interact with nucleotide substrates. Instead, we show that a conserved hydrophobic surface is likely to be important for SALP function and suggest that proteins are the likely binding partners. PMID:19567872

  1. Effect of chronic fractionated low-dose gamma irradiation on division potential of human embryonic cells in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Masami; Suzuki, Masao; Suzuki, Keiji; Watanabe, Kimiko (Yokohama City Univ. (Japan). Faculty of Medicine); Nakano, Kazushiro

    1991-12-01

    We investigated the in vitro phenotypic transformation of human embryo (HE) cells that were repeatedly irradiated (7.5 cGy once a week) throughout their life-span. Irradiation was repeated until the cells had accumulated 195 cGy (equivalent to the 26th passage). Samples of cells were assayed for survival by colony formation, as well as for mutation at the hypoxanthine guanine phosphoribosyl transferase (HGPRT) locus and for transformation by focus formation. The life-span (mean number of population doublings) of multiply irradiated cells with a total dose of 97.5 cGy was slightly but significantly prolonged over that of controls. After HE cells had accumulated 195 cGy, the maximum number of divisions increased to 130-160% of the number in non-irradiated control cells. Transformed foci were not observed until cells had accumulated 97.5 cGy, and then increased with the increasing accumulation of radiation. However, no cells showed immortality or expressed a malignant phenotype in vitro. (author).

  2. Energy Division annual progress report for period ending September 30, 1992

    Energy Technology Data Exchange (ETDEWEB)

    Counce, D.M.; Wolff, P.P. [eds.

    1993-04-01

    Energy Division`s mission is to provide innovative solutions to energy and related Issues of national and global importance through interdisciplinary research and development. Its goals and accomplishments are described in this annual progress report for FY 1992. Energy Division`s total expenditures in FY 1992 were $42.8 million. The work is supported by the US Department of Energy, the US Department of Defense, many other federal agencies, and some private organizations. Disciplines of the 116.5 technical staff members include engineering, social sciences, physical and life sciences, and mathematics and statistics. The division`s programmatic activities cover three main areas: (1) analysis and assessment, (2) energy conservation technologies, and (3) military transportation systems. Analysis and assessment activities involve energy and resource analysis, preparation of environmental assessments and impact statements, research on waste management, technology transfer, analysis of energy and environmental needs in developing countries, and civilian transportation analysis. Energy conservation technologies focus on electric power systems, building envelopes (walls, foundations, roofs, attics, and materials), and methods to improve energy efficiency in existing buildings. Military transportation systems conduct research for sponsors within the US military to improve the efficiency of military deployment, scheduling, and transportation coordination. Much of Energy Division`s research is valuable to other organizations as well as to sponsors. This information is disseminated by the staff`s involvement in professional and trade organizations and workshops; joint research with universities and private-sector firms; collaboration with state and local governments; presentation of work at conferences; and publication of research results in journals, reports, and conference proceedings.

  3. Comparative effects of 60Co γ-rays and neon and helium ions on cycle duration and division probability of EMT 6 cells. A time-lapse cinematography study

    International Nuclear Information System (INIS)

    Collyn-d'Hooghe, M.; Hemon, D.; Gilet, R.

    1981-01-01

    Exponentially growing cultures of EMT 6 cells were irradiated in vitro with neon ions, helium ions or 60 Co γ-rays. Time-lapse cinematography allowed the determination, for individual cells, of cycle duration, success of the mitotic division and the age of the cell at the moment of irradiation. Irradiation induced a significant mitotic delay increasing proportionally with the delivered dose. Using mitotic delay as an endpoint, the r.b.e. for neon ions with respect to 60 Co γ-rays was 3.3 +- 0.2 while for helium ions it was 1.2 +- 0.1. Mitotic delay was greatest in those cells that had progressed furthest in their cycle at the time of irradiation. No significant mitotic delay was observed in the post-irradiation generation. Division probability was significantly reduced by irradiation both in the irradiated and in the post-irradiated generation. The reduction in division probability obtained with 3 Gy of neon ions was similar to that obtained after irradiation with 6 Gy of helium ions or 60 Co γ-rays. (author)

  4. Comparative effects of 60Co gamma-rays and neon and helium ions on cycle duration and division probability of EMT 6 cells. A time-lapse cinematography study.

    Science.gov (United States)

    Collyn-d'Hooghe, M; Hemon, D; Gilet, R; Curtis, S B; Valleron, A J; Malaise, E P

    1981-03-01

    Exponentially growing cultures of EMT 6 cells were irradiated in vitro with neon ions, helium ions or 60Co gamma-rays. Time-lapse cinematography allowed the determination, for individual cells, of cycle duration, success of the mitotic division and the age of the cell at the moment of irradiation. Irradiation induced a significant mitotic delay increasing proportionally with the delivered dose. Using mitotic delay as an endpoint, the r.b.e. for neon ions with respect to 60Co gamma-rays was 3.3 +/- 0.2 while for helium ions it was 1.2 +/- 0.1. Mitotic delay was greatest in those cells that had progressed furthest in their cycle at the time of irradiation. No significant mitotic delay was observed in the post-irradiation generation. Division probability was significantly reduced by irradiation both in the irradiated and in the post-irradiated generation. The reduction in division probability obtained with 3 Gy of neon ions was similar to that obtained after irradiation with 6 Gy of helium ions or 60Co gamma-rays.

  5. The role of genes controlling the replication and cell division in the repair of radiation damage in Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Zhestyanikov, V D; Svetlova, M P; Tomilin, N V; Savel' eva, G E [AN SSSR, Leningrad. Inst. Tsitologii

    1975-01-01

    Mutations in genes controlling the replication (dnaEsup(ts), dnaBsup(ts), dnaGsup(ts) and cell division (lon) in Escherichia coli prevent the rejoining of the gamma radiation-induced single-strand breaks (dnaE in combination with polA1 mutation and dnaG at the restrictive temperature) and effective postreplication DNA repair in UV-irradiated cells (dnaG at the non-permissive temperature and lon mutation) and decrease the survival of UV- and gamma-irradiated bacteria.

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

    International Nuclear Information System (INIS)

    Rubin, N.A.

    1980-01-01

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

  7. Casein kinase II is required for proper cell division and acts as a negative regulator of centrosome duplication in Caenorhabditis elegans embryos

    Directory of Open Access Journals (Sweden)

    Jeffrey C. Medley

    2017-01-01

    Full Text Available Centrosomes are the primary microtubule-organizing centers that orchestrate microtubule dynamics during the cell cycle. The correct number of centrosomes is pivotal for establishing bipolar mitotic spindles that ensure accurate segregation of chromosomes. Thus, centrioles must duplicate once per cell cycle, one daughter per mother centriole, the process of which requires highly coordinated actions among core factors and modulators. Protein phosphorylation is shown to regulate the stability, localization and activity of centrosome proteins. Here, we report the function of Casein kinase II (CK2 in early Caenorhabditis elegans embryos. The catalytic subunit (KIN-3/CK2α of CK2 localizes to nuclei, centrosomes and midbodies. Inactivating CK2 leads to cell division defects, including chromosome missegregation, cytokinesis failure and aberrant centrosome behavior. Furthermore, depletion or inhibiting kinase activity of CK2 results in elevated ZYG-1 levels at centrosomes, restoring centrosome duplication and embryonic viability to zyg-1 mutants. Our data suggest that CK2 functions in cell division and negatively regulates centrosome duplication in a kinase-dependent manner.

  8. Disorganization of cell division of methicillin-resistant Staphylococcus aureus by methanolic extract from Phyllanthus columnaris stem bark

    Energy Technology Data Exchange (ETDEWEB)

    Adnalizawati, A. Siti Noor; Nazlina, I. [School of Biosciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Yaacob, W. A. [School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia)

    2013-11-27

    The in vitro activity of methanolic extract from Phyllanthus columnaris stem bark was studied against Methicillin-resistant Staphylococcus aureus (MRSA) ATCC 43300 and MRSA BM1 (clinical strain) using time-kill curves in conjunction with scanning and transmission electron microscopy. The extract showed more markedly bactericidal activity in MRSA BM1 clinical strain within less than 4 h by 6.25-12.5 mg/mL and within 6 h by 1.56 mg/mL. Scanning electron microscopy of MRSA BM1 revealed distortion of cell whilst transmission electron microscopy revealed disruption in cell wall division.

  9. Disorganization of cell division of methicillin-resistant Staphylococcus aureus by methanolic extract from Phyllanthus columnaris stem bark

    International Nuclear Information System (INIS)

    Adnalizawati, A. Siti Noor; Nazlina, I.; Yaacob, W. A.

    2013-01-01

    The in vitro activity of methanolic extract from Phyllanthus columnaris stem bark was studied against Methicillin-resistant Staphylococcus aureus (MRSA) ATCC 43300 and MRSA BM1 (clinical strain) using time-kill curves in conjunction with scanning and transmission electron microscopy. The extract showed more markedly bactericidal activity in MRSA BM1 clinical strain within less than 4 h by 6.25-12.5 mg/mL and within 6 h by 1.56 mg/mL. Scanning electron microscopy of MRSA BM1 revealed distortion of cell whilst transmission electron microscopy revealed disruption in cell wall division

  10. Bulletin of the Division of Electrical Engineering, 1987-1988, volume 3, number 2

    Science.gov (United States)

    1988-05-01

    A report is provided on the activities of the Division of Electrical Engineering of the National Research Council of Canada. The Division engages in the development of standards and test procedures, and undertakes applied research in support of Canadian industry, government departments, and universities. Technology transfer and collaborative research continue to grow in importance as focuses of Division activities. The Division is comprised of three sections: the Laboratory for Biomedical Engineering, the Laboratory for Electromagnetic and Power Engineering, and the Laboratory for Intelligent Systems. An agreement has been reached to commercially exploit the realtime multiprocessor operating system Harmony. The dielectrics group has made contract research agreements with industry from both Canada and the United States. The possibility of employing a new advanced laser vision camera, which can be mounted on a robot arm in a variety of industrial applications is being explored. Potential short-term spinoffs related to intelligent wheelchairs are being sought as part of the new interlaboratory program which has as its long-term objective the development of a mobile robot for health care applications. A program in applied artificial intelligence has been established. Initiatives in collaboration with outside groups include proposals for major institutes in areas ranging from police and security research to rehabilitation research, programs to enhance Canadian industrial competence working with the Canadian Manufacturers' Association and other government departments, and approaches to the utilization of existing facilities which will make them more valuable without significant financial expenditures.

  11. Is Longitudinal Division in Rod-Shaped Bacteria a Matter of Swapping Axis?

    Directory of Open Access Journals (Sweden)

    Tanneke den Blaauwen

    2018-05-01

    Full Text Available The morphology of bacterial species shows a wealth of variation from star-shaped to spherical and rod- to spiral-shaped, to mention a few. Their mode of growth and division is also very diverse and flexible ranging from polar growth and lateral surface increase to midcell expansion and from perpendicular to longitudinal asymmetric division. Gammaproteobacterial rod-shaped species such as Escherchia coli divide perpendicularly and grow in length, whereas the genetically very similar rod-shaped symbiotic Thiosymbion divide longitudinally, and some species even divide asynchronously while growing in width. The ovococcal Streptococcus pneumoniae also lengthens and divides perpendicularly, yet it is genetically very different from E. coli. Are these differences as dramatic as is suggested by visual inspection, or can they all be achieved by subtle variation in the regulation of the same protein complexes that synthesize the cell envelope? Most bacteria rely on the cytoskeletal polymer FtsZ to organize cell division, but only a subset of species use the actin homolog MreB for length growth, although some of them are morphologically not that different. Poles are usually negative determinant for cell division. Curved cell poles can be inert or active with respect to peptidoglycan synthesis, can localize chemotaxis and other sensing proteins or other bacterial equipment, such as pili, depending on the species. But what is actually the definition of a pole? This review discusses the possible common denominators for growth and division of distinct and similar bacterial species.

  12. Contribution of the Pmra Promoter to Expression of Genes in the Escherichia coli mra Cluster of Cell Envelope Biosynthesis and Cell Division Genes

    Science.gov (United States)

    Mengin-Lecreulx, Dominique; Ayala, Juan; Bouhss, Ahmed; van Heijenoort, Jean; Parquet, Claudine; Hara, Hiroshi

    1998-01-01

    Recently, a promoter for the essential gene ftsI, which encodes penicillin-binding protein 3 of Escherichia coli, was precisely localized 1.9 kb upstream from this gene, at the beginning of the mra cluster of cell division and cell envelope biosynthesis genes (H. Hara, S. Yasuda, K. Horiuchi, and J. T. Park, J. Bacteriol. 179:5802–5811, 1997). Disruption of this promoter (Pmra) on the chromosome and its replacement by the lac promoter (Pmra::Plac) led to isopropyl-β-d-thiogalactopyranoside (IPTG)-dependent cells that lysed in the absence of inducer, a defect which was complemented only when the whole region from Pmra to ftsW, the fifth gene downstream from ftsI, was provided in trans on a plasmid. In the present work, the levels of various proteins involved in peptidoglycan synthesis and cell division were precisely determined in cells in which Pmra::Plac promoter expression was repressed or fully induced. It was confirmed that the Pmra promoter is required for expression of the first nine genes of the mra cluster: mraZ (orfC), mraW (orfB), ftsL (mraR), ftsI, murE, murF, mraY, murD, and ftsW. Interestingly, three- to sixfold-decreased levels of MurG and MurC enzymes were observed in uninduced Pmra::Plac cells. This was correlated with an accumulation of the nucleotide precursors UDP–N-acetylglucosamine and UDP–N-acetylmuramic acid, substrates of these enzymes, and with a depletion of the pool of UDP–N-acetylmuramyl pentapeptide, resulting in decreased cell wall peptidoglycan synthesis. Moreover, the expression of ftsZ, the penultimate gene from this cluster, was significantly reduced when Pmra expression was repressed. It was concluded that the transcription of the genes located downstream from ftsW in the mra cluster, from murG to ftsZ, is also mainly (but not exclusively) dependent on the Pmra promoter. PMID:9721276

  13. Thermosensitive mutant of Bacillus subtilis deficient in uracil and cell division

    Energy Technology Data Exchange (ETDEWEB)

    Nagai, K; Some, H; Tamura, G

    1976-01-01

    Thermonsensitive division mutants were derived from Bacillus subtilis Marburg 168 thy trp/sub 2/ by means of membrane filtration after nitrosoguanidine mutagenesis. Among them, ts42 requiring uracil for normal growth at 48/sup 0/C was investigated. In the absence of uracil, the mutant cells grew normally at 37/sup 0/C and stopped dividing after temperature shift to 48/sup 0/C resulting in filaments of two to four times length of normal rods. The total cell number after the temperature shift increased two to three fold in 90 min and remained constant thereafter. The viable count after the temperature shift to 48/sup 0/C, increased 1.5 to 2 fold in initial 60 min and then decreased exponentially. A rapid restoration of colony forming ability was shown when the mutant cells were shifted back to the permissive temperature after 120 to 180 min of incubation at 48/sup 0/C or when uracil was introduced to the culture at 48/sup 0/C. This recovery of viability was partly observed even in the presence of chloramphenicol. The synthesis of RNA of this mutant was shown to decline 20 min after the temperature shift to 48/sup 0/C whereas the syntheses of DNA and protein proceeded for more than 80 min at that temperature. No newly isolated uracil requiring mutants formed filaments in the medium lacking uracil or showed growth pattern like ts42.

  14. Stochastic Individual-Based Modeling of Bacterial Growth and Division Using Flow Cytometry

    Directory of Open Access Journals (Sweden)

    Míriam R. García

    2018-01-01

    Full Text Available A realistic description of the variability in bacterial growth and division is critical to produce reliable predictions of safety risks along the food chain. Individual-based modeling of bacteria provides the theoretical framework to deal with this variability, but it requires information about the individual behavior of bacteria inside populations. In this work, we overcome this problem by estimating the individual behavior of bacteria from population statistics obtained with flow cytometry. For this objective, a stochastic individual-based modeling framework is defined based on standard assumptions during division and exponential growth. The unknown single-cell parameters required for running the individual-based modeling simulations, such as cell size growth rate, are estimated from the flow cytometry data. Instead of using directly the individual-based model, we make use of a modified Fokker-Plank equation. This only equation simulates the population statistics in function of the unknown single-cell parameters. We test the validity of the approach by modeling the growth and division of Pediococcus acidilactici within the exponential phase. Estimations reveal the statistics of cell growth and division using only data from flow cytometry at a given time. From the relationship between the mother and daughter volumes, we also predict that P. acidilactici divide into two successive parallel planes.

  15. Sonic hedgehog signaling regulates mode of cell division of early cerebral cortex progenitors and increases astrogliogenesis

    Directory of Open Access Journals (Sweden)

    Geissy LL Araújo

    2014-03-01

    Full Text Available The morphogen Sonic Hedgehog (SHH plays a critical role in the development of different tissues. In the central nervous system, SHH is well known to contribute to the patterning of the spinal cord and separation of the brain hemispheres. In addition, it has recently been shown that SHH signaling also contributes to the patterning of the telencephalon and establishment of adult neurogenic niches. In this work, we investigated whether SHH signaling influences the behavior of neural progenitors isolated from the dorsal telencephalon, which generate excitatory neurons and macroglial cells in vitro. We observed that SHH increases proliferation of cortical progenitors and generation of astrocytes, whereas blocking SHH signaling with cyclopamine has opposite effects. In both cases, generation of neurons did not seem to be affected. However, cell survival was broadly affected by blockade of SHH signaling. SHH effects were related to three different cell phenomena: mode of cell division, cell cycle length and cell growth. Together, our data in vitro demonstrate that SHH signaling controls cell behaviors that are important for proliferation of cerebral cortex progenitors, as well as differentiation and survival of neurons and astroglial cells.

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

    International Nuclear Information System (INIS)

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

    1979-01-01

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

  17. CDKL5 localizes at the centrosome and midbody and is required for faithful cell division.

    Science.gov (United States)

    Barbiero, Isabella; Valente, Davide; Chandola, Chetan; Magi, Fiorenza; Bergo, Anna; Monteonofrio, Laura; Tramarin, Marco; Fazzari, Maria; Soddu, Silvia; Landsberger, Nicoletta; Rinaldo, Cinzia; Kilstrup-Nielsen, Charlotte

    2017-07-24

    The cyclin-dependent kinase-like 5 (CDKL5) gene has been associated with rare neurodevelopmental disorders characterized by the early onset of seizures and intellectual disability. The CDKL5 protein is widely expressed in most tissues and cells with both nuclear and cytoplasmic localization. In post-mitotic neurons CDKL5 is mainly involved in dendritic arborization, axon outgrowth, and spine formation while in proliferating cells its function is still largely unknown. Here, we report that CDKL5 localizes at the centrosome and at the midbody in proliferating cells. Acute inactivation of CDKL5 by RNA interference (RNAi) leads to multipolar spindle formation, cytokinesis failure and centrosome accumulation. At the molecular level, we observed that, among the several midbody components we analyzed, midbodies of CDKL5-depleted cells were devoid of HIPK2 and its cytokinesis target, the extrachromosomal histone H2B phosphorylated at S14. Of relevance, expression of the phosphomimetic mutant H2B-S14D, which is capable of overcoming cytokinesis failure in HIPK2-defective cells, was sufficient to rescue spindle multipolarity in CDKL5-depleted cells. Taken together, these results highlight a hitherto unknown role of CDKL5 in regulating faithful cell division by guaranteeing proper HIPK2/H2B functions at the midbody.

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

    International Nuclear Information System (INIS)

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

    1978-01-01

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

  19. Chemical dissection of the cell cycle: probes for cell biology and anti-cancer drug development.

    Science.gov (United States)

    Senese, S; Lo, Y C; Huang, D; Zangle, T A; Gholkar, A A; Robert, L; Homet, B; Ribas, A; Summers, M K; Teitell, M A; Damoiseaux, R; Torres, J Z

    2014-10-16

    Cancer cell proliferation relies on the ability of cancer cells to grow, transition through the cell cycle, and divide. To identify novel chemical probes for dissecting the mechanisms governing cell cycle progression and cell division, and for developing new anti-cancer therapeutics, we developed and performed a novel cancer cell-based high-throughput chemical screen for cell cycle modulators. This approach identified novel G1, S, G2, and M-phase specific inhibitors with drug-like properties and diverse chemotypes likely targeting a broad array of processes. We further characterized the M-phase inhibitors and highlight the most potent M-phase inhibitor MI-181, which targets tubulin, inhibits tubulin polymerization, activates the spindle assembly checkpoint, arrests cells in mitosis, and triggers a fast apoptotic cell death. Importantly, MI-181 has broad anti-cancer activity, especially against BRAF(V600E) melanomas.

  20. Israel: the Division before Peace

    Directory of Open Access Journals (Sweden)

    Ferran Izquierdo Brichs

    2000-01-01

    Full Text Available The process of the Middle East peace negotiations at the beginning of the 1990s has its roots in the changes in the international system and in Israeli society. The end of the Cold War, the Gulf War in 1990-1991 and globalization forced all the region’s actors to resituate themselves within the new international context. However, Israeli society neither experienced the international changes in the same way as its neighbors nor did it undergo the same evolutionduring the conflict with the Arabs. Because of this, the debate over peace and the future of the occupied territories became a factor for political and ideological division. Influencing this debate were revised conceptions on security, the economy, and the role Israel should play in the world. The Middle East peace talks began because the strongest side in the conflict, Israel’s Labor government, came to perceive that the maintenance of the status quo was negative forits interests. From the Israeli point of view, the conflict had long been considered a zero-sum game despite the Palestinian’s compromises since the construction of the Palestinian State involved handing over part of the territory claimed by the Jews. Recent changes in the perceptions of Israeli’s own interests, though, led some sectors of Jewish society to re-think and diminish the supposed incompatibility between Palestine nationalism and Zionism, which then opened the doors towards peace. For the Labor government, the territorial occupation of all Palestine was no longer a central objective. In fact, the basic interests of the Labor party’s policies shifted due to the globalization of the international system. For Likud and the Zionist revisionists, however, the occupation and the colonization of Eretz Israel still form the basic ideology of the State –of its reason for being– for which even today both are associated with the national interest, together with Israel’s very survival. Seen this way, Israel

  1. Lymph Node Metastases and Prognosis in Left Upper Division Non-Small Cell Lung Cancers: The Impact of Interlobar Lymph Node Metastasis.

    Directory of Open Access Journals (Sweden)

    Hiroaki Kuroda

    Full Text Available Left upper division segmentectomy is one of the major pulmonary procedures; however, it is sometimes difficult to completely dissect interlobar lymph nodes. We attempted to clarify the prognostic importance of hilar and mediastinal nodes, especially of interlobar lymph nodes, in patients with primary non-small cell lung cancer (NSCLC located in the left upper division.We retrospectively studied patients with primary left upper lobe NSCLC undergoing surgical pulmonary resection (at least lobectomy with radical lymphadenectomy. The representative evaluation of therapeutic value from the lymph node dissection was determined using Sasako's method. This analysis was calculated by multiplying the frequency of metastasis to the station and the 5-year survival rate of the patients with metastasis to the station.We enrolled 417 patients (237 men, 180 women. Tumors were located in the lingular lobe and at the upper division of left upper lobe in 69 and 348 patients, respectively. The pathological nodal statuses were pN0 in 263 patients, pN1 in 70 patients, and pN2 in 84 patients. Lymph nodes #11 and #7 were significantly correlated with differences in node involvement in patients with left upper lobe NSCLC. Among those with left upper division NSCLC, the 5-year overall survival in pN1 was 31.5% for #10, 39.3% for #11, and 50.4% for #12U. The involvement of node #11 was 1.89-fold higher in the anterior segment than that in the apicoposterior segment. The therapeutic index of estimated benefit from lymph node dissection for #11 was 3.38, #4L was 1.93, and the aortopulmonary window was 4.86 in primary left upper division NSCLC.Interlobar node involvement is not rare in left upper division NSCLC, occurring in >20% cases. Furthermore, dissection of interlobar nodes was found to be beneficial in patients with left upper division NSCLC.

  2. Polyploid tumour cells elicit paradiploid progeny through depolyploidizing divisions and regulated autophagic degradation.

    Science.gov (United States)

    Erenpreisa, Jekaterina; Salmina, Kristine; Huna, Anda; Kosmacek, Elizabeth A; Cragg, Mark S; Ianzini, Fiorenza; Anisimov, Alim P

    2011-07-01

    'Neosis' describes the process whereby p53 function-deficient tumour cells undergo self-renewal after genotoxic damage apparently via senescing ETCs (endopolyploid tumour cells). We previously reported that autophagic digestion and extrusion of DNA occurs in ETC and subsequently revealed that self-renewal transcription factors are also activated under these conditions. Here, we further studied this phenomenon in a range of cell lines after genotoxic damage induced by gamma irradiation, ETO (etoposide) or PXT (paclitaxel) treatment. These experiments revealed that chromatin degradation by autophagy was compatible with continuing mitotic activity in ETC. While the actively polyploidizing primary ETC produced early after genotoxic insult activated self-renewal factors throughout the polygenome, the secondary ETC restored after failed multipolar mitosis underwent subnuclei differentiation. As such, only a subset of subnuclei continued to express OCT4 and NANOG, while those lacking these factors stopped DNA replication and underwent degradation and elimination through autophagy. The surviving subnuclei sequestered nascent cytoplasm to form subcells, while being retained within the confines of the old ETC. Finally, the preformed paradiploid subcells became released from their linking chromosome bridges through autophagy and subsequently began cell divisions. These data show that 'neotic' ETC resulting from genotoxically damaged p53 function-deficient tumour cells develop through a heteronuclear system differentiating the polyploid genome into rejuvenated 'viable' subcells (which provide mitotically propagating paradiploid descendents) and subnuclei, which become degraded and eliminated by autophagy. The whole process reduces aneuploidy in descendants of ETC.

  3. Metabolism and the Control of Cell Fate Decisions and Stem Cell Renewal

    Science.gov (United States)

    Ito, Kyoko; Ito, Keisuke

    2016-01-01

    Although the stem cells of various tissues remain in the quiescent state to maintain their undifferentiated state, they also undergo cell divisions as required, and if necessary, even a single stem cell is able to provide for lifelong tissue homeostasis. Stem cell populations are precisely controlled by the balance between their symmetric and asymmetric divisions, with their division patterns determined by whether the daughter cells involved retain their self-renewal capacities. Recent studies have reported that metabolic pathways and the distribution of mitochondria are regulators of the division balance of stem cells and that metabolic defects can shift division balance toward symmetric commitment, which leads to stem cell exhaustion. It has also been observed that in asymmetric division, old mitochondria, which are central metabolic organelles, are segregated to the daughter cell fated to cell differentiation, whereas in symmetric division, young and old mitochondria are equally distributed between both daughter cells. Thus, metabolism and mitochondrial biology play important roles in stem cell fate decisions. As these decisions directly affect tissue homeostasis, understanding their regulatory mechanisms in the context of cellular metabolism is critical. PMID:27482603

  4. Development and Application of a Two-Tier Multiple-Choice Diagnostic Test for High School Students' Understanding of Cell Division and Reproduction

    Science.gov (United States)

    Sesli, Ertugrul; Kara, Yilmaz

    2012-01-01

    This study involved the development and application of a two-tier diagnostic test for measuring students' understanding of cell division and reproduction. The instrument development procedure had three general steps: defining the content boundaries of the test, collecting information on students' misconceptions, and instrument development.…

  5. Division site selection in Escherichia coli involves dynamic redistribution of Min proteins within coiled structures that extend between the two cell poles

    Science.gov (United States)

    Shih, Yu-Ling; Le, Trung; Rothfield, Lawrence

    2003-06-01

    The MinCDE proteins of Escherichia coli are required for proper placement of the division septum at midcell. The site selection process requires the rapid oscillatory redistribution of the proteins from pole to pole. We report that the three Min proteins are organized into extended membrane-associated coiled structures that wind around the cell between the two poles. The pole-to-pole oscillation of the proteins reflects oscillatory changes in their distribution within the coiled structure. We also report that the E. coli MreB protein, which is required for maintaining the rod shape of the cell, also forms extended coiled structures, which are similar to the MreB structures that have previously been reported in Bacillus subtilis. The MreB and MinCDE coiled arrays do not appear identical. The results suggest that at least two functionally distinct cytoskeletal-like elements are present in E. coli and that structures of this type can undergo dynamic changes that play important roles in division site placement and possibly other aspects of the life of the cell.

  6. Simulation of E. coli gene regulation including overlapping cell cycles, growth, division, time delays and noise.

    Directory of Open Access Journals (Sweden)

    Ruoyu Luo

    Full Text Available Due to the complexity of biological systems, simulation of biological networks is necessary but sometimes complicated. The classic stochastic simulation algorithm (SSA by Gillespie and its modified versions are widely used to simulate the stochastic dynamics of biochemical reaction systems. However, it has remained a challenge to implement accurate and efficient simulation algorithms for general reaction schemes in growing cells. Here, we present a modeling and simulation tool, called 'GeneCircuits', which is specifically developed to simulate gene-regulation in exponentially growing bacterial cells (such as E. coli with overlapping cell cycles. Our tool integrates three specific features of these cells that are not generally included in SSA tools: 1 the time delay between the regulation and synthesis of proteins that is due to transcription and translation processes; 2 cell cycle-dependent periodic changes of gene dosage; and 3 variations in the propensities of chemical reactions that have time-dependent reaction rates as a consequence of volume expansion and cell division. We give three biologically relevant examples to illustrate the use of our simulation tool in quantitative studies of systems biology and synthetic biology.

  7. Chemical Biodynamics Division. Annual report 1979

    Energy Technology Data Exchange (ETDEWEB)

    1980-08-01

    The Chemical Biodynamics Division of LBL continues to conduct basic research on the dynamics of living cells and on the interaction of radiant energy with organic matter. Many aspects of this basic research are related to problems of environmental and health effects of fossil fuel combustion, solar energy conversion and chemical/ viral carcinogenesis.

  8. Optical code division multiple access fundamentals and applications

    CERN Document Server

    Prucnal, Paul R

    2005-01-01

    Code-division multiple access (CDMA) technology has been widely adopted in cell phones. Its astonishing success has led many to evaluate the promise of this technology for optical networks. This field has come to be known as Optical CDMA (OCDMA). Surveying the field from its infancy to the current state, Optical Code Division Multiple Access: Fundamentals and Applications offers the first comprehensive treatment of OCDMA from technology to systems.The book opens with a historical perspective, demonstrating the growth and development of the technologies that would eventually evolve into today's

  9. Determining Regulatory Networks Governing the Differentiation of Embryonic Stem Cells to Pancreatic Lineage

    Science.gov (United States)

    Banerjee, Ipsita

    2009-03-01

    Knowledge of pathways governing cellular differentiation to specific phenotype will enable generation of desired cell fates by careful alteration of the governing network by adequate manipulation of the cellular environment. With this aim, we have developed a novel method to reconstruct the underlying regulatory architecture of a differentiating cell population from discrete temporal gene expression data. We utilize an inherent feature of biological networks, that of sparsity, in formulating the network reconstruction problem as a bi-level mixed-integer programming problem. The formulation optimizes the network topology at the upper level and the network connectivity strength at the lower level. The method is first validated by in-silico data, before applying it to the complex system of embryonic stem (ES) cell differentiation. This formulation enables efficient identification of the underlying network topology which could accurately predict steps necessary for directing differentiation to subsequent stages. Concurrent experimental verification demonstrated excellent agreement with model prediction.

  10. Induction of prophage lambda during the division cycle of Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Worsey, M J; Wilkins, B M [Leicester Univ. (UK). Dept. of Genetics

    1975-01-01

    When synchronous populations of Escherichia coli B/r (lambda) were exposed to low doses of ultraviolet light, the yield of infective centres varied with cell age. The yield was highest if the lysogenic bacteria were irradiated at a time which coincides approximately with the termination of rounds of DNA replication and it was lowest when dividing cells were irradiated. No such variation was detected following either irradiation of excision-defective lysogenic cells or thermal induction of lambda cI857 prophage in irradiated bacteria. It is suggested that the variation reflects a relationship between prophage induction and inhibition of cell division. This hypothesis is supported by data showing that irradiation-promoted induction and curtailed division in E. coli K12 dnaA mutants which were dividing in the absence of DNA replication.

  11. Induction of prophage lambda during the division cycle of Escherichia coli

    International Nuclear Information System (INIS)

    Worsey, M.J.; Wilkins, B.M.

    1975-01-01

    When synchronous populations of Escherichia coli B/r (lambda) were exposed to low doses of ultraviolet light, the yield of infective centres varied with cell age. The yield was highest if the lysogenic bacteria were irradiated at a time which coincides approximately with the termination of rounds of DNA replication and it was lowest when dividing cells were irradiated. No such variation was detected following either irradiation of excision-defective lysogenic cells or thermal induction of lambda cI857 prophage in irradiated bacteria. It is suggested that the variation reflects a relationship between prophage induction and inhibition of cell division. This hypothesis is supported by data showing that irradiation-promoted induction and curtailed division in E. coli K12 dnaA mutants which were dividing in the absence of DNA replication. (orig.) [de

  12. Identification of proteins likely to be involved in morphogenesis, cell division, and signal transduction in Planctomycetes by comparative genomics.

    Science.gov (United States)

    Jogler, Christian; Waldmann, Jost; Huang, Xiaoluo; Jogler, Mareike; Glöckner, Frank Oliver; Mascher, Thorsten; Kolter, Roberto

    2012-12-01

    Members of the Planctomycetes clade share many unusual features for bacteria. Their cytoplasm contains membrane-bound compartments, they lack peptidoglycan and FtsZ, they divide by polar budding, and they are capable of endocytosis. Planctomycete genomes have remained enigmatic, generally being quite large (up to 9 Mb), and on average, 55% of their predicted proteins are of unknown function. Importantly, proteins related to the unusual traits of Planctomycetes remain largely unknown. Thus, we embarked on bioinformatic analyses of these genomes in an effort to predict proteins that are likely to be involved in compartmentalization, cell division, and signal transduction. We used three complementary strategies. First, we defined the Planctomycetes core genome and subtracted genes of well-studied model organisms. Second, we analyzed the gene content and synteny of morphogenesis and cell division genes and combined both methods using a "guilt-by-association" approach. Third, we identified signal transduction systems as well as sigma factors. These analyses provide a manageable list of candidate genes for future genetic studies and provide evidence for complex signaling in the Planctomycetes akin to that observed for bacteria with complex life-styles, such as Myxococcus xanthus.

  13. ALIX and ESCRT-III coordinately control cytokinetic abscission during germline stem cell division in vivo.

    Directory of Open Access Journals (Sweden)

    Åsmund H Eikenes

    2015-01-01

    Full Text Available Abscission is the final step of cytokinesis that involves the cleavage of the intercellular bridge connecting the two daughter cells. Recent studies have given novel insight into the spatiotemporal regulation and molecular mechanisms controlling abscission in cultured yeast and human cells. The mechanisms of abscission in living metazoan tissues are however not well understood. Here we show that ALIX and the ESCRT-III component Shrub are required for completion of abscission during Drosophila female germline stem cell (fGSC division. Loss of ALIX or Shrub function in fGSCs leads to delayed abscission and the consequent formation of stem cysts in which chains of daughter cells remain interconnected to the fGSC via midbody rings and fusome. We demonstrate that ALIX and Shrub interact and that they co-localize at midbody rings and midbodies during cytokinetic abscission in fGSCs. Mechanistically, we show that the direct interaction between ALIX and Shrub is required to ensure cytokinesis completion with normal kinetics in fGSCs. We conclude that ALIX and ESCRT-III coordinately control abscission in Drosophila fGSCs and that their complex formation is required for accurate abscission timing in GSCs in vivo.

  14. Applied Chemistry Division progress report for the period 1990-1992

    International Nuclear Information System (INIS)

    Bharadwaj, S.R.; Kishore, K.; Ramshesh, V.

    1993-01-01

    The report covers the research and development (R and D) activities of the Applied Chemistry Division for the period January 1990 to December, 1992. R and D programmes of the Division are formulated to study the chemical aspects related to nuclear power plants and heavy water plants. The Division also gives consultancy to DAE units and outside agencies on water chemistry problems. The thrust areas of the Division's R and D programmes are : decontamination of nuclear facilities, metal water interaction of the materials used in PHT system, chemistry of soluble poisons, biofouling and its control in cooling water circuits, and treatment of cooling waters. Other major R and D activities are in the areas of: solid state reactions and high temperature thermodynamics, primary coolant water chemistry, speciation studies in metal amine systems, high temperature aqueous radiation chemistry. The Division was engaged in studies in novel areas such as dental implants, remote sealing of pipes in MS pipes, and cold fusion. The Division also designed and fabricated instruments like the Knudsen cell mass spectrometer, calorimeters and developed required software. All these R and D activities are reported in the form of individual summaries. A list of publications from the Division and a list of the staff members of the Division are given at the end of the report. (author). tabs., figs., appendices

  15. PDK1 Is a Regulator of Epidermal Differentiation that Activates and Organizes Asymmetric Cell Division

    Directory of Open Access Journals (Sweden)

    Teruki Dainichi

    2016-05-01

    Full Text Available Asymmetric cell division (ACD in a perpendicular orientation promotes cell differentiation and organizes the stratified epithelium. However, the upstream cues regulating ACD have not been identified. Here, we report that phosphoinositide-dependent kinase 1 (PDK1 plays a critical role in establishing ACD in the epithelium. Production of phosphatidyl inositol triphosphate (PIP3 is localized to the apical side of basal cells. Asymmetric recruitment of atypical protein kinase C (aPKC and partitioning defective (PAR 3 is impaired in PDK1 conditional knockout (CKO epidermis. PDK1CKO keratinocytes do not undergo calcium-induced activation of aPKC or IGF1-induced activation of AKT and fail to differentiate. PDK1CKO epidermis shows decreased expression of Notch, a downstream effector of ACD, and restoration of Notch rescues defective expression of differentiation-induced Notch targets in vitro. We therefore propose that PDK1 signaling regulates the basal-to-suprabasal switch in developing epidermis by acting as both an activator and organizer of ACD and the Notch-dependent differentiation program.

  16. Informal caregivers’ views on the division of responsibilities between themselves and professionals : a scoping review

    NARCIS (Netherlands)

    Wittenberg, Yvette; Kwekkeboom, Rick; Staaks, Janneke; Verhoeff, Arnoud; de Boer, Alice

    2017-01-01

    This scoping review focuses on the views of informal caregivers regarding the division of care responsibilities between citizens, governments and professionals and the question of to what extent professionals take these views into account during collaboration with them. In Europe, the normative

  17. Characterization of the minimum domain required for targeting budding yeast myosin II to the site of cell division

    Directory of Open Access Journals (Sweden)

    Tolliday Nicola J

    2006-06-01

    Full Text Available Abstract Background All eukaryotes with the exception of plants use an actomyosin ring to generate a constriction force at the site of cell division (cleavage furrow during mitosis and meiosis. The structure and filament forming abilities located in the C-terminal or tail region of one of the main components, myosin II, are important for localising the molecule to the contractile ring (CR during cytokinesis. However, it remains poorly understood how myosin II is recruited to the site of cell division and how this recruitment relates to myosin filament assembly. Significant conservation between species of the components involved in cytokinesis, including those of the CR, allows the use of easily genetically manipulated organisms, such as budding yeast (Saccharomyces cerevisiae, in the study of cytokinesis. Budding yeast has a single myosin II protein, named Myo1. Unlike most other class II myosins, the tail of Myo1 has an irregular coiled coil. In this report we use molecular genetics, biochemistry and live cell imaging to characterize the minimum localisation domain (MLD of budding yeast Myo1. Results We show that the MLD is a small region in the centre of the tail of Myo1 and that it is both necessary and sufficient for localisation of Myo1 to the yeast bud neck, the pre-determined site of cell division. Hydrodynamic measurements of the MLD, purified from bacteria or yeast, show that it is likely to exist as a trimer. We also examine the importance of a small region of low coiled coil forming probability within the MLD, which we call the hinge region. Removal of the hinge region prevents contraction of the CR. Using fluorescence recovery after photobleaching (FRAP, we show that GFP-tagged MLD is slightly more dynamic than the GFP-tagged full length molecule but less dynamic than the GFP-tagged Myo1 construct lacking the hinge region. Conclusion Our results define the intrinsic determinant for the localization of budding yeast myosin II and show

  18. Impact of government incentives in the profitability of green energy production using fuel cells in Colombia.

    Directory of Open Access Journals (Sweden)

    Bernardo A. Potosí-Guerrero

    2016-07-01

    Full Text Available Fuel cells are a technological alternative to produce green energy, however, high costs make fuel cell a non-profitable option. This paper analyses the impact of the Colombian government incentives in the profitability of fuel cells. The analysis is based on the total operation cost of the fuel cell in three representative applications: residential, office and building elevator. The economic viability of fuel cell generation in those cases is contrasted with classical solutions like diesel generators and standard grid to provide a reference framework. Such results enable to evaluate the effectiveness of the Colombian government incentives in promoting the use of fuel cells over other less environmental-friendly options such as diesel generators. Finally, new incentives are proposed by subsidies offered by other countries with higher fuel cell penetration into their electric market. All the analyses are supported in simulations performed with a mathematical model parameterized using the characteristics of commercial devices.

  19. Fine-tuning of actin dynamics by the HSPB8-BAG3 chaperone complex facilitates cytokinesis and contributes to its impact on cell division.

    Science.gov (United States)

    Varlet, Alice Anaïs; Fuchs, Margit; Luthold, Carole; Lambert, Herman; Landry, Jacques; Lavoie, Josée N

    2017-07-01

    The small heat shock protein HSPB8 and its co-chaperone BAG3 are proposed to regulate cytoskeletal proteostasis in response to mechanical signaling in muscle cells. Here, we show that in dividing cells, the HSPB8-BAG3 complex is instrumental to the accurate disassembly of the actin-based contractile ring during cytokinesis, a process required to allow abscission of daughter cells. Silencing of HSPB8 markedly decreased the mitotic levels of BAG3 in HeLa cells, supporting its crucial role in BAG3 mitotic functions. Cells depleted of HSPB8 were delayed in cytokinesis, remained connected via a disorganized intercellular bridge, and exhibited increased incidence of nuclear abnormalities that result from failed cytokinesis (i.e., bi- and multi-nucleation). Such phenotypes were associated with abnormal accumulation of F-actin at the intercellular bridge of daughter cells at telophase. Remarkably, the actin sequestering drug latrunculin A, like the inhibitor of branched actin polymerization CK666, normalized F-actin during cytokinesis and restored proper cell division in HSPB8-depleted cells, implicating deregulated actin dynamics as a cause of abscission failure. Moreover, this HSPB8-dependent phenotype could be corrected by rapamycin, an autophagy-promoting drug, whereas it was mimicked by drugs impairing lysosomal function. Together, the results further support a role for the HSPB8-BAG3 chaperone complex in quality control of actin-based structure dynamics that are put under high tension, notably during cell cytokinesis. They expand a so-far under-appreciated connection between selective autophagy and cellular morphodynamics that guide cell division.

  20. Kinetics of human lymphocyte division and chromosomal radiosensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Bianchi, N O; Bianchi, M S; Larramendy, M [Instituto Multidisciplinario de Biologia Celular, La Plata (Argentinia)

    1979-12-01

    Human blood from normal donors was irradiated with 200 R during the G/sub 0/ phase, and the X-ray sensitivity of early and late dividing lymphocytes in culture was expressed as percentage of induced dicentrics. Cells in first or subsequent divisions were individualized by BrdU-Giemsa techniques. Lymphocytes in the first division at 40, 44 and 72 h after the start of culture had a lower sensitivity to radiation than lymphocytes making their first division at 48, 52 and 56 h. It was observed that: (a) the combination of radiation followed by BrdU did not increase the clastoyenic action of X-rays, (b)X-rays in the dose and duration used in our cultures did not increase the frequency of SCEs, and (c) minor changes in culture conditions probably influenced the frequency of SCEs.

  1. Lymph Node Metastases and Prognosis in Left Upper Division Non-Small Cell Lung Cancers: The Impact of Interlobar Lymph Node Metastasis

    Science.gov (United States)

    Kuroda, Hiroaki; Sakao, Yukinori; Mun, Mingyon; Uehara, Hirofumi; Nakao, Masayuki; Matsuura, Yousuke; Mizuno, Tetsuya; Sakakura, Noriaki; Motoi, Noriko; Ishikawa, Yuichi; Yatabe, Yasushi; Nakagawa, Ken; Okumura, Sakae

    2015-01-01

    Background Left upper division segmentectomy is one of the major pulmonary procedures; however, it is sometimes difficult to completely dissect interlobar lymph nodes. We attempted to clarify the prognostic importance of hilar and mediastinal nodes, especially of interlobar lymph nodes, in patients with primary non-small cell lung cancer (NSCLC) located in the left upper division. Methods We retrospectively studied patients with primary left upper lobe NSCLC undergoing surgical pulmonary resection (at least lobectomy) with radical lymphadenectomy. The representative evaluation of therapeutic value from the lymph node dissection was determined using Sasako’s method. This analysis was calculated by multiplying the frequency of metastasis to the station and the 5-year survival rate of the patients with metastasis to the station. Results We enrolled 417 patients (237 men, 180 women). Tumors were located in the lingular lobe and at the upper division of left upper lobe in 69 and 348 patients, respectively. The pathological nodal statuses were pN0 in 263 patients, pN1 in 70 patients, and pN2 in 84 patients. Lymph nodes #11 and #7 were significantly correlated with differences in node involvement in patients with left upper lobe NSCLC. Among those with left upper division NSCLC, the 5-year overall survival in pN1 was 31.5% for #10, 39.3% for #11, and 50.4% for #12U. The involvement of node #11 was 1.89-fold higher in the anterior segment than that in the apicoposterior segment. The therapeutic index of estimated benefit from lymph node dissection for #11 was 3.38, #4L was 1.93, and the aortopulmonary window was 4.86 in primary left upper division NSCLC. Conclusions Interlobar node involvement is not rare in left upper division NSCLC, occurring in >20% cases. Furthermore, dissection of interlobar nodes was found to be beneficial in patients with left upper division NSCLC. PMID:26247881

  2. Cell proliferation alterations in Chlorella cells under stress conditions

    International Nuclear Information System (INIS)

    Rioboo, Carmen; O'Connor, Jose Enrique; Prado, Raquel; Herrero, Concepcion; Cid, Angeles

    2009-01-01

    Very little is known about growth and proliferation in relation to the cell cycle regulation of algae. The lack of knowledge is even greater when referring to the potential toxic effects of pollutants on microalgal cell division. To assess the effect of terbutryn, a triazine herbicide, on the proliferation of the freshwater microalga Chlorella vulgaris three flow cytometric approaches were used: (1) in vivo cell division using 5-,6-carboxyfluorescein diacetate succinimidyl ester (CFSE) staining was measured, (2) the growth kinetics were determined by cytometric cell counting and (3) cell viability was evaluated with the membrane-impermeable double-stranded nucleic acid stain propidium iodide (PI). The results obtained in the growth kinetics study using CFSE to identify the microalgal cell progeny were consistent with those determined by cytometric cell counting. In all C. vulgaris cultures, each mother cell had undergone only one round of division through the 96 h of assay and the cell division occurred during the dark period. Cell division of the cultures exposed to the herbicide was asynchronous. Terbutryn altered the normal number of daughter cells (4 autospores) obtained from each mother cell. The number was only two in the cultures treated with 250 nM. The duration of the lag phase after the exposure to terbutryn could be dependent on the existence of a critical cell size to activate cytoplasmic division. Cell size, complexity and fluorescence of chlorophyll a of the microalgal cells presented a marked light/dark (day/night) cycle, except in the non-dividing 500 nM cultures, where terbutryn arrested cell division at the beginning of the cycle. Viability results showed that terbutryn has an algastatic effect in C. vulgaris cells at this concentration. The rapid and precise determination of cell proliferation by CFSE staining has allowed us to develop a model for assessing both the cell cycle of C. vulgaris and the in vivo effects of pollutants on growth and

  3. Cell proliferation alterations in Chlorella cells under stress conditions

    Energy Technology Data Exchange (ETDEWEB)

    Rioboo, Carmen [Laboratorio de Microbiologia, Facultad de Ciencias, Universidad de A Coruna, Campus da Zapateira s/n, 15008 A Coruna (Spain); O' Connor, Jose Enrique [Laboratorio de Citomica, Unidad Mixta de Investigacion CIPF-UVEG, Centro de Investigacion Principe Felipe, Avda. Autopista del Saler, 16, 46013 Valencia (Spain); Prado, Raquel; Herrero, Concepcion [Laboratorio de Microbiologia, Facultad de Ciencias, Universidad de A Coruna, Campus da Zapateira s/n, 15008 A Coruna (Spain); Cid, Angeles, E-mail: cid@udc.es [Laboratorio de Microbiologia, Facultad de Ciencias, Universidad de A Coruna, Campus da Zapateira s/n, 15008 A Coruna (Spain)

    2009-09-14

    Very little is known about growth and proliferation in relation to the cell cycle regulation of algae. The lack of knowledge is even greater when referring to the potential toxic effects of pollutants on microalgal cell division. To assess the effect of terbutryn, a triazine herbicide, on the proliferation of the freshwater microalga Chlorella vulgaris three flow cytometric approaches were used: (1) in vivo cell division using 5-,6-carboxyfluorescein diacetate succinimidyl ester (CFSE) staining was measured, (2) the growth kinetics were determined by cytometric cell counting and (3) cell viability was evaluated with the membrane-impermeable double-stranded nucleic acid stain propidium iodide (PI). The results obtained in the growth kinetics study using CFSE to identify the microalgal cell progeny were consistent with those determined by cytometric cell counting. In all C. vulgaris cultures, each mother cell had undergone only one round of division through the 96 h of assay and the cell division occurred during the dark period. Cell division of the cultures exposed to the herbicide was asynchronous. Terbutryn altered the normal number of daughter cells (4 autospores) obtained from each mother cell. The number was only two in the cultures treated with 250 nM. The duration of the lag phase after the exposure to terbutryn could be dependent on the existence of a critical cell size to activate cytoplasmic division. Cell size, complexity and fluorescence of chlorophyll a of the microalgal cells presented a marked light/dark (day/night) cycle, except in the non-dividing 500 nM cultures, where terbutryn arrested cell division at the beginning of the cycle. Viability results showed that terbutryn has an algastatic effect in C. vulgaris cells at this concentration. The rapid and precise determination of cell proliferation by CFSE staining has allowed us to develop a model for assessing both the cell cycle of C. vulgaris and the in vivo effects of pollutants on growth and

  4. Mitotic Spindle Asymmetry: A Wnt/PCP-Regulated Mechanism Generating Asymmetrical Division in Cortical Precursors

    Directory of Open Access Journals (Sweden)

    Delphine Delaunay

    2014-01-01

    Full Text Available The regulation of asymmetric cell division (ACD during corticogenesis is incompletely understood. We document that spindle-size asymmetry (SSA between the two poles occurs during corticogenesis and parallels ACD. SSA appears at metaphase and is maintained throughout division, and we show it is necessary for proper neurogenesis. Imaging of spindle behavior and division outcome reveals that neurons preferentially arise from the larger-spindle pole. Mechanistically, SSA magnitude is controlled by Wnt7a and Vangl2, both members of the Wnt/planar cell polarity (PCP-signaling pathway, and relayed to the cell cortex by P-ERM proteins. In vivo, Vangl2 and P-ERM downregulation promotes early cell-cycle exit and prevents the proper generation of late-born neurons. Thus, SSA is a core component of ACD that is conserved in invertebrates and vertebrates and plays a key role in the tight spatiotemporal control of self-renewal and differentiation during mammalian corticogenesis.

  5. Tissue Engineering Stem Cells - An e-Governance Strategy.

    Science.gov (United States)

    Grange, Simon

    2011-01-01

    The rules of governance are changing. They are necessarily becoming more stringent as interventions offered to treat conditions carry unpredictable side effects, often associated with novel therapeutic vectors. The clinical relevance of this relates to the obligations of those involved in research, to ensure the best protection for subjects whilst encouraging the development of the field. Existing evidence supports the concept of e-Governance both in operational health research and more broadly in the strategic domain of policy formation. Building on the impact of the UK Comprehensive Research Network and recent EU Directives, it is now possible to focus on the issues of regulation for cell therapies in musculoskeletal science through the development of the Advanced Therapeutic Medicinal Products (ATMP) category of research products. This article reviews the framework that has borne this and the need for more detailed Virtual Research Integration and Collaboration (VRIC) systems to ensure regulatory compliance. Technology research and development plans must develop in close association between tissue engineering and treating clinicians. The scope of this strategy relates to the handling of human tissues the transport and storage of specimens in accordance with current EU directives and the Human Tissue Authority (HTA) regulations.

  6. Identification of Wnt Pathway Target Genes Regulating the Division and Differentiation of Larval Seam Cells and Vulval Precursor Cells in Caenorhabditis elegans.

    Science.gov (United States)

    Gorrepati, Lakshmi; Krause, Michael W; Chen, Weiping; Brodigan, Thomas M; Correa-Mendez, Margarita; Eisenmann, David M

    2015-06-05

    The evolutionarily conserved Wnt/β-catenin signaling pathway plays a fundamental role during metazoan development, regulating numerous processes including cell fate specification, cell migration, and stem cell renewal. Wnt ligand binding leads to stabilization of the transcriptional effector β-catenin and upregulation of target gene expression to mediate a cellular response. During larval development of the nematode Caenorhabditis elegans, Wnt/β-catenin pathways act in fate specification of two hypodermal cell types, the ventral vulval precursor cells (VPCs) and the lateral seam cells. Because little is known about targets of the Wnt signaling pathways acting during larval VPC and seam cell differentiation, we sought to identify genes regulated by Wnt signaling in these two hypodermal cell types. We conditionally activated Wnt signaling in larval animals and performed cell type-specific "mRNA tagging" to enrich for VPC and seam cell-specific mRNAs, and then used microarray analysis to examine gene expression compared to control animals. Two hundred thirty-nine genes activated in response to Wnt signaling were identified, and we characterized 50 genes further. The majority of these genes are expressed in seam and/or vulval lineages during normal development, and reduction of function for nine genes caused defects in the proper division, fate specification, fate execution, or differentiation of seam cells and vulval cells. Therefore, the combination of these techniques was successful at identifying potential cell type-specific Wnt pathway target genes from a small number of cells and at increasing our knowledge of the specification and behavior of these C. elegans larval hypodermal cells. Copyright © 2015 Gorrepati et al.

  7. Yeast casein kinase 2 governs morphology, biofilm formation, cell wall integrity, and host cell damage of Candida albicans.

    Science.gov (United States)

    Jung, Sook-In; Rodriguez, Natalie; Irrizary, Jihyun; Liboro, Karl; Bogarin, Thania; Macias, Marlene; Eivers, Edward; Porter, Edith; Filler, Scott G; Park, Hyunsook

    2017-01-01

    The regulatory networks governing morphogenesis of a pleomorphic fungus, Candida albicans are extremely complex and remain to be completely elucidated. This study investigated the function of C. albicans yeast casein kinase 2 (CaYck2p). The yck2Δ/yck2Δ strain displayed constitutive pseudohyphae in both yeast and hyphal growth conditions, and formed enhanced biofilm under non-biofilm inducing condition. This finding was further supported by gene expression analysis of the yck2Δ/yck2Δ strain which showed significant upregulation of UME6, a key transcriptional regulator of hyphal transition and biofilm formation, and cell wall protein genes ALS3, HWP1, and SUN41, all of which are associated with morphogenesis and biofilm architecture. The yck2Δ/yck2Δ strain was hypersensitive to cell wall damaging agents and had increased compensatory chitin deposition in the cell wall accompanied by an upregulation of the expression of the chitin synthase genes, CHS2, CHS3, and CHS8. Absence of CaYck2p also affected fungal-host interaction; the yck2Δ/yck2Δ strain had significantly reduced ability to damage host cells. However, the yck2Δ/yck2Δ strain had wild-type susceptibility to cyclosporine and FK506, suggesting that CaYck2p functions independently from the Ca+/calcineurin pathway. Thus, in C. albicans, Yck2p is a multifunctional kinase that governs morphogenesis, biofilm formation, cell wall integrity, and host cell interactions.

  8. Effects of the Scientific Argumentation Based Learning Process on Teaching the Unit of Cell Division and Inheritance to Eighth Grade Students

    Science.gov (United States)

    Balci, Ceyda; Yenice, Nilgun

    2016-01-01

    The aim of this study is to analyse the effects of scientific argumentation based learning process on the eighth grade students' achievement in the unit of "cell division and inheritance". It also deals with the effects of this process on their comprehension about the nature of scientific knowledge, their willingness to take part in…

  9. How cells grow and divide: mathematical analysis confirms demand for the cell cycle

    International Nuclear Information System (INIS)

    Kwon, Hyun Woong; Choi, M Y

    2012-01-01

    Eukaryotes usually grow through cell growth and division. How cells grow and divide is essential to life because too small or too large cells cannot function well. In order for an organism to survive even under a condition where cell growth and division processes are independent of each other, cells must have an appropriate growth factor, growth rate and division rate. To determine them, we derive a time evolution equation for the size distribution of cells from the master equation describing changes in the cell size due to growth and in the total number of cells due to division. It is found that long-time behaviors of moments of the size distribution divide the parameter space, consisting of the growth factor and the ratio of the division rate to the growth rate, into infinitely many regions. Examining the properties of each region, we conclude that growth with a small growth factor may be disastrous; this demonstrates the demand for the cell cycle consisting of coordinated growth and division processes. (paper)

  10. Informal caregivers' views on the division of responsibilities between themselves and professionals: A scoping review.

    Science.gov (United States)

    Wittenberg, Yvette; Kwekkeboom, Rick; Staaks, Janneke; Verhoeff, Arnoud; de Boer, Alice

    2017-12-18

    This scoping review focuses on the views of informal caregivers regarding the division of care responsibilities between citizens, governments and professionals and the question of to what extent professionals take these views into account during collaboration with them. In Europe, the normative discourse on informal care has changed. Retreating governments and decreasing residential care increase the need to enhance the collaboration between informal caregivers and professionals. Professionals are assumed to adequately address the needs and wishes of informal caregivers, but little is known about informal caregivers' views on the division of care responsibilities. We performed a scoping review and searched for relevant studies published between 2000 and September 1, 2016 in seven databases. Thirteen papers were included, all published in Western countries. Most included papers described research with a qualitative research design. Based on the opinion of informal caregivers, we conclude that professionals do not seem to explicitly take into account the views of informal caregivers about the division of responsibilities during their collaboration with them. Roles of the informal caregivers and professionals are not always discussed and the division of responsibilities sometimes seems unclear. Acknowledging the role and expertise of informal caregivers seems to facilitate good collaboration, as well as attitudes such as professionals being open and honest, proactive and compassionate. Inflexible structures and services hinder good collaboration. Asking informal caregivers what their opinion is about the division of responsibilities could improve clarity about the care that is given by both informal caregivers and professionals and could improve their collaboration. Educational programs in social work, health and allied health professions should put more emphasis on this specific characteristic of collaboration. © 2017 The Authors. Health and Social Care in the

  11. N-acylated peptides derived from human lactoferricin perturb organization of cardiolipin and phosphatidylethanolamine in cell membranes and induce defects in Escherichia coli cell division.

    Directory of Open Access Journals (Sweden)

    Dagmar Zweytick

    Full Text Available Two types of recently described antibacterial peptides derived from human lactoferricin, either nonacylated or N-acylated, were studied for their different interaction with membranes of Escherichia coli in vivo and in model systems. Electron microscopy revealed striking effects on the bacterial membrane as both peptide types induced formation of large membrane blebs. Electron and fluorescence microscopy, however demonstrated that only the N-acylated peptides partially induced the generation of oversized cells, which might reflect defects in cell-division. Further a different distribution of cardiolipin domains on the E. coli membrane was shown only in the presence of the N-acylated peptides. The lipid was distributed over the whole bacterial cell surface, whereas cardiolipin in untreated and nonacylated peptide-treated cells was mainly located at the septum and poles. Studies with bacterial membrane mimics, such as cardiolipin or phosphatidylethanolamine revealed that both types of peptides interacted with the negatively charged lipid cardiolipin. The nonacylated peptides however induced segregation of cardiolipin into peptide-enriched and peptide-poor lipid domains, while the N-acylated peptides promoted formation of many small heterogeneous domains. Only N-acylated peptides caused additional severe effects on the main phase transition of liposomes composed of pure phosphatidylethanolamine, while both peptide types inhibited the lamellar to hexagonal phase transition. Lipid mixtures of phosphatidylethanolamine and cardiolipin revealed anionic clustering by all peptide types. However additional strong perturbation of the neutral lipids was only seen with the N-acylated peptides. Nuclear magnetic resonance demonstrated different conformational arrangement of the N-acylated peptide in anionic and zwitterionic micelles revealing possible mechanistic differences in their action on different membrane lipids. We hypothesized that both peptides kill

  12. A Strategic Governance Review for Multi-Organizational Systems of Education, Training, and Professional Development

    National Research Council Canada - National Science Library

    Daley, Glenn

    2003-01-01

    .... Because of the division of financial responsibility, command authority, and workforce planning within DoD, the effectiveness of the system depends on its capacity for governance of the organizations...

  13. Making sense of Wnt signaling – linking hair cell regeneration to development

    Directory of Open Access Journals (Sweden)

    Lina eJansson

    2015-03-01

    Full Text Available Wnt signaling is a highly conserved pathway crucial for development and homeostasis of multicellular organisms. Secreted Wnt ligands bind Frizzled receptors to regulate diverse processes such as axis patterning, cell division, and cell fate specification. They also serve to govern self-renewal of somatic stem cells in several adult tissues. The complexity of the pathway can be attributed to the myriad of Wnt and Frizzled combinations as well as its diverse context-dependent functions. In the developing mouse inner ear, Wnt signaling plays diverse roles, including specification of the otic placode and patterning of the otic vesicle. At later stages, its activity governs sensory hair cell specification, cell cycle regulation, and hair cell orientation. In regenerating sensory organs from non-mammalian species, Wnt signaling can also regulate the extent of proliferative hair cell regeneration. This review describes the current knowledge of the roles of Wnt signaling and Wnt-responsive cells in hair cell development and regeneration. We also discuss possible future directions and the potential application and limitation of Wnt signaling in augmenting hair cell regeneration.

  14. Dissecting the role of conformational change and membrane binding by the bacterial cell division regulator MinE in the stimulation of MinD ATPase activity.

    Science.gov (United States)

    Ayed, Saud H; Cloutier, Adam D; McLeod, Laura J; Foo, Alexander C Y; Damry, Adam M; Goto, Natalie K

    2017-12-15

    The bacterial cell division regulators MinD and MinE together with the division inhibitor MinC localize to the membrane in concentrated zones undergoing coordinated pole-to-pole oscillation to help ensure that the cytokinetic division septum forms only at the mid-cell position. This dynamic localization is driven by MinD-catalyzed ATP hydrolysis, stimulated by interactions with MinE's anti-MinCD domain. This domain is buried in the 6-β-stranded MinE "closed" structure, but is liberated for interactions with MinD, giving rise to a 4-β-stranded "open" structure through an unknown mechanism. Here we show that MinE-membrane interactions induce a structural change into a state resembling the open conformation. However, MinE mutants lacking the MinE membrane-targeting sequence stimulated higher ATP hydrolysis rates than the full-length protein, indicating that binding to MinD is sufficient to trigger this conformational transition in MinE. In contrast, conformational change between the open and closed states did not affect stimulation of ATP hydrolysis rates in the absence of membrane binding, although the MinD-binding residue Ile-25 is critical for this conformational transition. We therefore propose an updated model where MinE is brought to the membrane through interactions with MinD. After stimulation of ATP hydrolysis, MinE remains bound to the membrane in a state that does not catalyze additional rounds of ATP hydrolysis. Although the molecular basis for this inhibited state is unknown, previous observations of higher-order MinE self-association may explain this inhibition. Overall, our findings have general implications for Min protein oscillation cycles, including those that regulate cell division in bacterial pathogens. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  15. E-Division semiannual report. Progress report, June 1--December 31, 1977. [Electronics and Instrumentation Division, LASL

    Energy Technology Data Exchange (ETDEWEB)

    Kelley, P.A. (comp.)

    1978-03-01

    The status of the programs and projects of the Electronics Division is reported for the period of June through December 1977. The presentation is divided into three sections: Research, Engineering Support, and Technical Services. Each of these sections presents the activities and accomplishments of the corresponding branch within the Division. The primary goal of the Research and Development branch is to advance technology for future applications. The primary goal of the Engineering Support branch is to apply advanced technology to laboratory and material problems. The primary goal of the Technical Services branch is to provide a technical base and support for Laboratory programs. These goals are reflected in this report. Among the subject areas included are the following: radiation detectors, temperature monitoring, electromagnetic probing, Josephson junction switching devices, fiber optics, high-temperature electronics, HVAC systems, microprocessors, fuel cell-powered vehicles, laser fusion.

  16. Computational Fair Division

    DEFF Research Database (Denmark)

    Branzei, Simina

    Fair division is a fundamental problem in economic theory and one of the oldest questions faced through the history of human society. The high level scenario is that of several participants having to divide a collection of resources such that everyone is satisfied with their allocation -- e.g. two...... heirs dividing a car, house, and piece of land inherited. The literature on fair division was developed in the 20th century in mathematics and economics, but computational work on fair division is still sparse. This thesis can be seen as an excursion in computational fair division divided in two parts....... The first part tackles the cake cutting problem, where the cake is a metaphor for a heterogeneous divisible resource such as land, time, mineral deposits, and computer memory. We study the equilibria of classical protocols and design an algorithmic framework for reasoning about their game theoretic...

  17. The Antibacterial Cell Division Inhibitor PC190723 Is an FtsZ Polymer-stabilizing Agent That Induces Filament Assembly and Condensation*

    Science.gov (United States)

    Andreu, José M.; Schaffner-Barbero, Claudia; Huecas, Sonia; Alonso, Dulce; Lopez-Rodriguez, María L.; Ruiz-Avila, Laura B.; Núñez-Ramírez, Rafael; Llorca, Oscar; Martín-Galiano, Antonio J.

    2010-01-01

    Cell division protein FtsZ can form single-stranded filaments with a cooperative behavior by self-switching assembly. Subsequent condensation and bending of FtsZ filaments are important for the formation and constriction of the cytokinetic ring. PC190723 is an effective bactericidal cell division inhibitor that targets FtsZ in the pathogen Staphylococcus aureus and Bacillus subtilis and does not affect Escherichia coli cells, which apparently binds to a zone equivalent to the binding site of the antitumor drug taxol in tubulin (Haydon, D. J., Stokes, N. R., Ure, R., Galbraith, G., Bennett, J. M., Brown, D. R., Baker, P. J., Barynin, V. V., Rice, D. W., Sedelnikova, S. E., Heal, J. R., Sheridan, J. M., Aiwale, S. T., Chauhan, P. K., Srivastava, A., Taneja, A., Collins, I., Errington, J., and Czaplewski, L. G. (2008) Science 312, 1673–1675). We have found that the benzamide derivative PC190723 is an FtsZ polymer-stabilizing agent. PC190723 induced nucleated assembly of Bs-FtsZ into single-stranded coiled protofilaments and polymorphic condensates, including bundles, coils, and toroids, whose formation could be modulated with different solution conditions. Under conditions for reversible assembly of Bs-FtsZ, PC190723 binding reduced the GTPase activity and induced the formation of straight bundles and ribbons, which was also observed with Sa-FtsZ but not with nonsusceptible Ec-FtsZ. The fragment 2,6-difluoro-3-methoxybenzamide also induced Bs-FtsZ bundling. We propose that polymer stabilization by PC190723 suppresses in vivo FtsZ polymer dynamics and bacterial division. The biochemical action of PC190723 on FtsZ parallels that of the microtubule-stabilizing agent taxol on the eukaryotic structural homologue tubulin. Both taxol and PC190723 stabilize polymers against disassembly by preferential binding to each assembled protein. It is yet to be investigated whether both ligands target structurally related assembly switches. PMID:20212044

  18. Dnmt1-dependent Chk1 pathway suppression is protective against neuron division.

    Science.gov (United States)

    Oshikawa, Mio; Okada, Kei; Tabata, Hidenori; Nagata, Koh-Ichi; Ajioka, Itsuki

    2017-09-15

    Neuronal differentiation and cell-cycle exit are tightly coordinated, even in pathological situations. When pathological neurons re-enter the cell cycle and progress through the S phase, they undergo cell death instead of division. However, the mechanisms underlying mitotic resistance are mostly unknown. Here, we have found that acute inactivation of retinoblastoma (Rb) family proteins (Rb, p107 and p130) in mouse postmitotic neurons leads to cell death after S-phase progression. Checkpoint kinase 1 (Chk1) pathway activation during the S phase prevented the cell death, and allowed the division of cortical neurons that had undergone acute Rb family inactivation, oxygen-glucose deprivation (OGD) or in vivo hypoxia-ischemia. During neurogenesis, cortical neurons became protected from S-phase Chk1 pathway activation by the DNA methyltransferase Dnmt1, and underwent cell death after S-phase progression. Our results indicate that Chk1 pathway activation overrides mitotic safeguards and uncouples neuronal differentiation from mitotic resistance. © 2017. Published by The Company of Biologists Ltd.

  19. Governance and the geography of authority: modalities of authorisation and the transnational governing of climate change

    OpenAIRE

    Harriet Bulkeley

    2012-01-01

    Within debates about the emergence and nature of governance, it has become commonplace to debate the whereabouts and possibilities of authority. Traditionally, authority is conceived as a property of some actor or institution and is regarded as divisible over time and space. Drawing on theories of power, in which it is regarded as constitutive of social relations, this paper proposes an alternative account of authority in which it is seen as one form of power that can be enacted towards three...

  20. On infinitely divisible semimartingales

    DEFF Research Database (Denmark)

    Basse-O'Connor, Andreas; Rosiński, Jan

    2015-01-01

    to non Gaussian infinitely divisible processes. First we show that the class of infinitely divisible semimartingales is so large that the natural analog of Stricker's theorem fails to hold. Then, as the main result, we prove that an infinitely divisible semimartingale relative to the filtration generated...... by a random measure admits a unique decomposition into an independent increment process and an infinitely divisible process of finite variation. Consequently, the natural analog of Stricker's theorem holds for all strictly representable processes (as defined in this paper). Since Gaussian processes...... are strictly representable due to Hida's multiplicity theorem, the classical Stricker's theorem follows from our result. Another consequence is that the question when an infinitely divisible process is a semimartingale can often be reduced to a path property, when a certain associated infinitely divisible...

  1. A mechanism for ParB-dependent waves of ParA, a protein related to DNA segregation during cell division in prokaryotes

    DEFF Research Database (Denmark)

    Hunding, Axel; Gerdes, Kenn; Charbon, Gitte Ebersbach

    2003-01-01

    in an autocatalytic process. We discuss this mechanism in relation to recent models for MinDE oscillations in E.coli and to microtubule degradation in mitosis. The study points to an ancestral role for the presented pattern types in generating bipolarity in prokaryotes and eukaryotes.......Prokaryotic plasmids encode partitioning (par) loci involved in segregation of DNA to daughter cells at cell division. A functional fusion protein consisting of Walker-type ParA ATPase and green fluorescent protein (Gfp) oscillates back and forth within nucleoid regions with a wave period of about...

  2. Modification of radiation-induced division delay by caffeine analogues and dibutyryl cyclic AMP

    Energy Technology Data Exchange (ETDEWEB)

    Kimler, B.F.; Leeper, D.B.; Snyder, M.H.; Rowley, R.; Schneiderman, M.H. (Thomas Jefferson Univ., Philadelphia, PA (USA). Hospital)

    1982-01-01

    The mitotic selection procedure for cell cycle analysis was utilized to investigate the concentration-dependent modification of x-radiation-induced division delay in Chinese hamster ovary (CHO) cells by methyl xanthines (caffeine, theophylline, and theobromine) and by dibutyryl cyclic AMP. The methyl xanthines (concentrations from 0.5 to 1000 ..mu..g/ml) all reduced radiation-induced division delay with the effect being linear between approximately 100 and 1000 ..mu..g/ml. After doses of 100-300 rad, delay was reduced by 75, 94 or 83 per cent at 1000 ..mu..g/ml for each drug, respectively. However, the addition of dibutyryl cyclic AMP had an opposite effect: radiation-induced delay was increased by the concentration range of 0.3 to 300 ..mu..g/ml. These results indicate that in mammalian cells the control of cell cycle progression and the modification of radiation-induced division delay are not simply related to intracellular levels of cyclic AMP. Rather, there appear to be at least two competing mechanisms which are differentially affected by caffeine analogues or by direct addition of dibutyryl cyclic AMP. The direct effect of caffeine and the methyl xanthines on membrane calcium permeability is considered.

  3. Modification of radiation-induced division delay by caffeine analogues and dibutyryl cyclic AMP

    International Nuclear Information System (INIS)

    Kimler, B.F.; Leeper, D.B.; Snyder, M.H.; Rowley, R.; SChneiderman, M.H.

    1982-01-01

    The mitotic selection procedure for cell cycle analysis was utilized to investigate the concentration-dependent modification of x-radiation-induced division delay in Chinese hamster ovary (CHO) cells by methyl xanthines (caffeine, theophylline, and theobromine) and by dibutyryl cyclic AMP. The methyl xanthines (concentrations from 0.5 to 1000 μg/ml) all reduced radiation-induced division delay with the effect being linear between approximately 100 and 1000 μg/ml. After doses of 100-300 rad, delay was reduced by 75, 94 or 83 per cent at 1000 μg/ml for each drug, respectively. However, the addition of dibutyryl cyclic AMP had an opposite effect: radiation-induced delay was increased by the concentration range of 0.3 to 300 μg/ml. These results indicate that in mammalian cells the control of cell cycle progression and the modification of radiation-induced division delay are not simply related to intracellular levels of cyclic AMP. Rather, there appear to be at least two competing mechanisms which are differentially affected by caffeine analogues or by direct addition of dibutyryl cyclic AMP. The direct effect of caffeine and the methyl xanthines on membrane calcium permeability is considered. (author)

  4. Chemical Technology Division. Annual technical report, 1995

    Energy Technology Data Exchange (ETDEWEB)

    Laidler, J.J.; Myles, K.M.; Green, D.W.; McPheeters, C.C.

    1996-06-01

    Highlights of the Chemical Technology (CMT) Division`s activities during 1995 are presented. In this period, CMT conducted research and development in the following areas: (1) electrochemical technology, including advanced batteries and fuel cells; (2) methods for treatment of hazardous waste and mixed hazardous/radioactive waste; (3) the reaction of nuclear waste glass and spent fuel under conditions expected for an unsaturated repository; (4) processes for separating and recovering selected elements from waste streams, concentrating low-level radioactive waste streams with advanced evaporator technology, and producing {sup 99}Mo from low-enriched uranium; (5) electrometallurgical treatment of different types of spent nuclear fuel in storage at Department of Energy sites; and (6) physical chemistry of selected materials in environments simulating those of fission and fusion energy systems.

  5. Division of Finance Homepage

    Science.gov (United States)

    Top Department of Administration logo Alaska Department of Administration Division of Finance Search Search the Division of Finance site DOF State of Alaska Finance Home Content Area Accounting Charge Cards You are here Administration / Finance Division of Finance Updates IRIS Expenditure Object Codes

  6. Advances in nickel hydrogen technology at Yardney Battery Division

    Science.gov (United States)

    Bentley, J. G.; Hall, A. M.

    1987-01-01

    The current major activites in nickel hydrogen technology being addressed at Yardney Battery Division are outlined. Five basic topics are covered: an update on life cycle testing of ManTech 50 AH NiH2 cells in the LEO regime; an overview of the Air Force/industry briefing; nickel electrode process upgrading; 4.5 inch cell development; and bipolar NiH2 battery development.

  7. The legislative consequences of internal conflict and inter-party divisions

    Directory of Open Access Journals (Sweden)

    Matthias Haber

    2015-06-01

    Full Text Available Governments must respond quickly to pressing economic and societal problems. However, institutional rules, public opinion and unanticipated world events often delay the legislative process. Building on theories of legislative decision-making and intra-party politics, this paper shows that the speed at which bills pass is also driven by the governing party’s internal cohesiveness and its ideological distance to the opposition. Governing parties that are internally divided have greater difficulty in forming the legislative majorities necessary to pass laws quickly, especially if their preferences are further away from the opposition. I test these hypotheses using a novel collection of laws passed in the UK Parliament and conference speeches given by Labour and Conservative party members over a 10-year period. I use automated text classification techniques to determine the relative location of actors’ preferences and the level of intra-party disagreement. I then predict the duration of lawmaking based on the government’s recent internal level of conflict and its distance to the opposition. The results complement mounting evidence that parties’ internal policy divisions hold important implications for parties’ performance in government.

  8. The effect of caffeine on radiation-induced division delay

    International Nuclear Information System (INIS)

    Snyder, M.H.; Kimler, B.F.; Leeper, D.B.

    1977-01-01

    Caffeine (100 μg/ml) was added to monolayer cultures of Chinese hamster ovary cells coincident with 60 Co γ-irradiation (75 to 300 rad). The results indicated that caffeine (at concentrations that did not perturb cell-cycle progression as monitored by the mitotic selection technique) exerted a protective effect against radiation-induced division delay. This protection consisted of an increase in the number of cells that were refractory to the radiation insult, as well as a decrease in the average time that non-refractory cells were delayed before they recovered their ability to progress through the cell cycle. (U.K.)

  9. Argonne Physics Division Colloquium

    Science.gov (United States)

    [Argonne Logo] [DOE Logo] Physics Division Home News Division Information Contact PHY Org Chart Physics Division Colloquium Auditorium, Building 203, Argonne National Laboratory Fridays at 11:00 AM 2017 : Sereres Johnston 15 Sep 2017 Joint Physics and Materials Science Colloquium J. C. Séamus Davis, Cornell

  10. Involvement of YODA and mitogen activated protein kinase 6 in Arabidopsis post-embryogenic root development through auxin up-regulation and cell division plane orientation

    Czech Academy of Sciences Publication Activity Database

    Smékalová, V.; Luptovčiak, I.; Komis, G.; Šamajová, O.; Ovečka, M.; Doskočilová, A.; Takáč, T.; Vadovič, P.; Novák, Ondřej; Pechan, T.; Ziemann, A.; Košútová, P.; Šamaj, J.

    2014-01-01

    Roč. 203, č. 4 (2014), s. 1175-1193 ISSN 0028-646X R&D Projects: GA MŠk(CZ) LO1204 Institutional support: RVO:61389030 Keywords : Arabidopsis * cell division plane * MAP65-1 Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 7.672, year: 2014

  11. The garlic allelochemical diallyl disulfide affects tomato root growth by influencing cell division, phytohormone balance and expansin gene expression

    Directory of Open Access Journals (Sweden)

    Fang Cheng

    2016-08-01

    Full Text Available Diallyl disulfide (DADS is a volatile organosulfur compound derived from garlic (Allium sativum L., and it is known as an allelochemical responsible for the strong allelopathic potential of garlic. The anticancer properties of DADS have been studied in experimental animals and various types of cancer cells, but to date, little is known about its mode of action as an allelochemical at the cytological level. The current research presents further studies on the effects of DADS on tomato (Solanum lycopersicum L. seed germination, root growth, mitotic index and cell size in root meristem, as well as the phytohormone levels and expression profile of auxin biosynthesis genes (FZYs, auxin transport genes (SlPINs and expansin genes (EXPs in tomato root. The results showed a biphasic, dose-dependent effect on tomato seed germination and root growth under different DADS concentrations. Lower concentrations (0.01-0.62 mM of DADS significantly promoted root growth, whereas higher levels (6.20-20.67 mM showed inhibitory effects. Cytological observations showed that the cell length of root meristem was increased and that the mitotic activity of meristematic cells in seedling root tips was enhanced at lower concentrations of DADS. In contrast, DADS at higher concentrations inhibited root growth by affecting both the length and division activity of meristematic cells. However, the cell width of the root meristem was not affected. Additionally, DADS increased the IAA and ZR contents of seedling roots in a dose-dependent manner. The influence on IAA content may be mediated by the up-regulation of FZYs and PINs. Further investigation into the underlying mechanism revealed that the expression levels of tomato EXPs were significantly affected by DADS. The expression levels of EXPB2 and beta-expansin precursor were increased after 3 d, and those of EXP1, EXPB3 and EXLB1 were increased after 5 d of DADS treatment (0.41 mM. This result suggests that tomato root growth

  12. Modification of cell volume and proliferative capacity of Pseudokirchneriella subcapitata cells exposed to metal stress

    International Nuclear Information System (INIS)

    Machado, Manuela D.; Soares, Eduardo V.

    2014-01-01

    Highlights: •Metals induce morphological alterations on P. subcapitata. •Algal cell cycle consists: mother cell growth; cell division, with two nucleus divisions; release of four autospores. •Cu(II) and Cr(VI) arrest cell growth before the first nuclear division. •Cd(II) arrests cell growth after the second nuclear division but before the cytokinesis. •The approach used can be useful in the elucidation of different modes of action of pollutants. -- Abstract: The impact of metals (Cd, Cr, Cu and Zn) on growth, cell volume and cell division of the freshwater alga Pseudokirchneriella subcapitata exposed over a period of 72 h was investigated. The algal cells were exposed to three nominal concentrations of each metal: low (closed to 72 h-EC 10 values), intermediate (closed to 72 h-EC 50 values) and high (upper than 72 h-EC 90 values). The exposure to low metal concentrations resulted in a decrease of cell volume. On the contrary, for the highest metal concentrations an increase of cell volume was observed; this effect was particularly notorious for Cd and less pronounced for Zn. Two behaviours were found when algal cells were exposed to intermediate concentrations of metals: Cu(II) and Cr(VI) induced a reduction of cell volume, while Cd(II) and Zn(II) provoked an opposite effect. The simultaneous nucleus staining and cell image analysis, allowed distinguishing three phases in P. subcapitata cell cycle: growth of mother cell; cell division, which includes two divisions of the nucleus; and, release of four autospores. The exposure of P. subcapitata cells to the highest metal concentrations resulted in the arrest of cell growth before the first nucleus division [for Cr(VI) and Cu(II)] or after the second nucleus division but before the cytokinesis (release of autospores) when exposed to Cd(II). The different impact of metals on algal cell volume and cell-cycle progression, suggests that different toxicity mechanisms underlie the action of different metals

  13. Nuclear materials transportation workshops: USDOE outreach to local governments

    International Nuclear Information System (INIS)

    1987-01-01

    To provide direct outreach to local governments, the Transportation Management Division of the United States Department of Energy asked the Urban Consortium and its Energy Task Force to assemble representatives for two workshops focusing on the transport of nuclear materials. The first session, for jurisdictions east of the Mississippi River, was held in New Orleans on May 5--6, 1988; the second was conducted on June 6--7, 1988 in Denver for jurisdictions to the west. Twenty local government professionals with management or operational responsibility for hazardous materials transportation within their jurisdictions were selected to attend each workshop. The discussions identified five major areas of concern to local government professionals; coordination; training; information resources; marking and placarding; and responder resources. Integrated federal, state, and local levels of government emerged as a priority coordination issue along with the need for expanded availability of training and training resources for first-reponders

  14. The influence of arachidonic acid metabolites on cell division in the intestinal epithelium and in colonic tumors.

    Science.gov (United States)

    Petry, F M; Tutton, P J; Barkla, D H

    1984-09-01

    Various metabolites of arachidonic acid are now known to influence cell division. In this paper the effects on cell proliferation of arachidonic acid, some inhibitors of arachidonic acid metabolism and some analogs of arachidonic acid metabolites is described. The epithelial cell proliferation rate in the jejunum, in the descending colon and in dimethylhydrazine-induced tumors of rat colon was measured using a stathmokinetic technique. Administration of arachidonic acid resulted in retardation of cell proliferation in each of the tissues examined. A cyclooxygenase inhibitor (Flurbiprofen) prevented this effect of arachidonic acid in the jejunal crypts and in colonic tumors, but not in colonic crypts. In contrast, inhibitors of both cyclooxygenase and lipoxygenase (Benoxaprofen and BW755c) prevented the effect of arachidonic acid in the colonic crypts and reduced its effect on colonic tumours but did not alter its effect on the jejunum. An inhibitor of thromoboxane A2 synthetase (U51,605) was also able to prevent the inhibitory effect of arachidonic acid on colonic tumors. Treatment with 16,16-dimethyl PGE2 inhibited cell proliferation in jejunal crypts and in colonic tumors, as did a thromboxane A2 mimicking agent, U46619. Nafazatrom, an agent that stimulates prostacyclin synthesis and inhibits lypoxygenase, promoted cell proliferation in the jejunal crypts and colonic crypts, but inhibited cell proliferation in colonic tumours.

  15. Tissue Engineering Stem Cells – An e-Governance Strategy

    Science.gov (United States)

    Grange, Simon

    2011-01-01

    The rules of governance are changing. They are necessarily becoming more stringent as interventions offered to treat conditions carry unpredictable side effects, often associated with novel therapeutic vectors. The clinical relevance of this relates to the obligations of those involved in research, to ensure the best protection for subjects whilst encouraging the development of the field. Existing evidence supports the concept of e-Governance both in operational health research and more broadly in the strategic domain of policy formation. Building on the impact of the UK Comprehensive Research Network and recent EU Directives, it is now possible to focus on the issues of regulation for cell therapies in musculoskeletal science through the development of the Advanced Therapeutic Medicinal Products (ATMP) category of research products. This article reviews the framework that has borne this and the need for more detailed Virtual Research Integration and Collaboration (VRIC) systems to ensure regulatory compliance. Technology research and development plans must develop in close association between tissue engineering and treating clinicians. The scope of this strategy relates to the handling of human tissues the transport and storage of specimens in accordance with current EU directives and the Human Tissue Authority (HTA) regulations. PMID:21886693

  16. The central dogma of cell biology.

    Science.gov (United States)

    Cooper, S

    1981-06-01

    The Continuum Model proposes that preparations for DNA synthesis occur continuously during all phases of the division cycle. Various stimuli activate cell proliferation by changing the rate of initiator (protein) synthesis. Cell division does not initiate any process regulating cell proliferation. Cell division is the end of a process and the beginning of nothing. The alternative model which has cell proliferation regulated in the G1 phase of the division cycle is reexamined and the two types of evidence for this model, G1-variability and G1-arrest are shown to be compatible with the Continuum Model. Here, the Continuum Model is generalized to produce a new look at the logic of the division cycle in prokaryotes and eukaryotes. This new view, the Central Dogma of Cell Biology, is presented and two predictions are made. I propose that (i) cell division does not have any regulatory function, and (ii) that DNA synthesis may, indeed, have some affect on the synthesis of initiator.

  17. Divisible ℤ-modules

    Directory of Open Access Journals (Sweden)

    Futa Yuichi

    2016-03-01

    Full Text Available In this article, we formalize the definition of divisible ℤ-module and its properties in the Mizar system [3]. We formally prove that any non-trivial divisible ℤ-modules are not finitely-generated.We introduce a divisible ℤ-module, equivalent to a vector space of a torsion-free ℤ-module with a coefficient ring ℚ. ℤ-modules are important for lattice problems, LLL (Lenstra, Lenstra and Lovász base reduction algorithm [15], cryptographic systems with lattices [16] and coding theory [8].

  18. Progress report of Applied Physics Division. July 1984 - June 1985

    International Nuclear Information System (INIS)

    2004-01-01

    The activities of the Division during 1984/85 were again directed towards the general program objectives of the past two years. A shift in emphasis resulted in some organization changes. The increased importance of nuclear safeguards research in the Government's support for the International Atomic Energy Agency program has prompted a re-arrangement of the nuclear physics and science activities. Dr JR. Bird holds the responsibility for the Nuclear Science Section comprising the Nuclear Applications Group, Biomedical and Reactor Applications Group and the Neutron Scattering Group. The newly formed Safeguards and Nuclear Physics Section is headed by Dr J.W. Boldeman and includes the Safeguards Group and Nuclear Physics Group. The organization of the remainder of the Division is unchanged. The work on the electronic properties of hydrogen in silicon has been particularly rewarding and the plasma physics studies received recognition with an IAEA sponsored workshop on Compact Torus Research held in Sydney in March 1985 (author)

  19. Progress report of Applied Physics Division. July 1984 - June 1985

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    The activities of the Division during 1984/85 were again directed towards the general program objectives of the past two years. A shift in emphasis resulted in some organization changes. The increased importance of nuclear safeguards research in the Government's support for the International Atomic Energy Agency program has prompted a re-arrangement of the nuclear physics and science activities. Dr JR. Bird holds the responsibility for the Nuclear Science Section comprising the Nuclear Applications Group, Biomedical and Reactor Applications Group and the Neutron Scattering Group. The newly formed Safeguards and Nuclear Physics Section is headed by Dr J.W. Boldeman and includes the Safeguards Group and Nuclear Physics Group. The organization of the remainder of the Division is unchanged. The work on the electronic properties of hydrogen in silicon has been particularly rewarding and the plasma physics studies received recognition with an IAEA sponsored workshop on Compact Torus Research held in Sydney in March 1985 (author)

  20. Cancer vaccine enhanced, non-tumor-reactive CD8(+) T cells exhibit a distinct molecular program associated with "division arrest anergy".

    Science.gov (United States)

    Beyer, Marc; Karbach, Julia; Mallmann, Michael R; Zander, Thomas; Eggle, Daniela; Classen, Sabine; Debey-Pascher, Svenja; Famulok, Michael; Jäger, Elke; Schultze, Joachim L

    2009-05-15

    Immune-mediated tumor rejection relies on fully functional T-cell responses and neutralization of an adverse tumor microenvironment. In clinical trials, we detected peptide-specific but non-tumor-reactive and therefore not fully functional CD8(+) T cells post-vaccination against tumor antigens. Understanding the molecular mechanisms behind nontumor reactivity will be a prerequisite to overcome this CD8(+) T-cell deviation. We report that these non-tumor-reactive CD8(+) T cells are characterized by a molecular program associated with hallmarks of "division arrest anergy." Non-tumor-reactive CD8(+) T cells are characterized by coexpression of CD7, CD25, and CD69 as well as elevated levels of lck(p505) and p27(kip1). In vivo quantification revealed high prevalence of non-tumor-reactive CD8(+) T cells with increased levels during cancer vaccination. Furthermore, their presence was associated with a trend toward shorter survival. Dynamics and frequencies of non-target-reactive CD8(+) T cells need to be further addressed in context of therapeutic vaccine development in cancer, chronic infections, and autoimmune diseases.

  1. Mammary Stem Cell Self-Renewal Is Regulated by Slit2/Robo1 Signaling through SNAI1 and mINSC

    Directory of Open Access Journals (Sweden)

    Mimmi S. Ballard

    2015-10-01

    Full Text Available Tissue homeostasis requires somatic stem cell maintenance; however, mechanisms regulating this process during organogenesis are not well understood. Here, we identify asymmetrically renewing basal and luminal stem cells in the mammary end bud. We demonstrate that SLIT2/ROBO1 signaling regulates the choice between self-renewing asymmetric cell divisions (ACDs and expansive symmetric cell divisions (SCDs by governing Inscuteable (mInsc, a key member of the spindle orientation machinery, through the transcription factor Snail (SNAI1. Loss of SLIT2/ROBO1 signaling increases SNAI1 in the nucleus. Overexpression of SNAI1 increases mInsc expression, an effect that is inhibited by SLIT2 treatment. Increased mInsc does not change cell proliferation in the mammary gland (MG but instead causes more basal cap cells to divide via SCD, at the expense of ACD, leading to more stem cells and larger outgrowths. Together, our studies provide insight into how the number of mammary stem cells is regulated by the extracellular cue SLIT2.

  2. CORPORATE GOVERNANCE IN INDIA: AN ANALYSIS

    Directory of Open Access Journals (Sweden)

    Meghna Thapar

    2017-03-01

    Full Text Available Corporate governance is a process, relation and mechanism set up for the corporations and firms based on certain guidelines and principles by which a company is controlled and directed. The principles provided in the system ensure that the company is governed in a way that it is able to set and achieve its goals and objectives in the context of the social, regulatory and market environment, and is able to maximize profits and also benefit those whose interest is involved in it, in the long run. The division and distribution of rights and responsibilities among different participants in the corporation (such as the board of directors, managers, shareholders, creditors, auditors, regulators, and other stakeholders and inclusion of the rules and procedures for making decisions in corporate affairs are identified with the help of Corporate Governance mechanism and guidelines. The need to make corporate governance in India transparent was felt after the high profile corporate governance failure scams like the stock market scam, the UTI scam, Ketan Parikh scam, Satyam scam, which were severely criticized by the shareholders. Thus, Corporate Governance is not just company administration but more than that and includes monitoring the actions, policies, practices, and decisions of corporations, their agents, and affected stakeholders thereby ensuring fair, efficient and transparent functioning of the corporate management system. By this paper, the authors intend to examine the concept of corporate governance in India with regard to the provisions of corporate governance under the Companies Act 2013. The paper will highlight the importance and need of corporate governance in India. We will also discuss the important case laws which contributed immensely in the emergence of corporate governance in India.

  3. Characterization of a putative spindle assembly checkpoint kinase Mps1, suggests its involvement in cell division, morphogenesis and oxidative stress tolerance in Candida albicans.

    Directory of Open Access Journals (Sweden)

    Mohan Kamthan

    Full Text Available In Saccharomyces cerevisiae MPS1 is one of the major protein kinase that governs the spindle checkpoint pathway. The S. cerevisiae structural homolog of opportunistic pathogen Candida albicans CaMPS1, is indispensable for the cell viability. The essentiality of Mps1 was confirmed by Homozygote Trisome test. To determine its biological function in this pathogen conditional mutant was generated through regulatable MET3 promoter. Examination of heterozygous and conditional (+Met/Cys mps1 mutants revealed a mitosis specific arrest phenotype, where mutants showed large buds with undivided nuclei. Flowcytometry analysis revealed abnormal ploidy levels in mps1 mutant. In presence of anti-microtubule drug Nocodazole, mps1 mutant showed a dramatic loss of viability suggesting a role of Mps1 in Spindle Assembly Checkpoint (SAC activation. These mutants were also defective in microtubule organization. Moreover, heterozygous mutant showed defective in-vitro yeast to hyphae morphological transition. Growth defect in heterozygous mutant suggest haploinsufficiency of this gene. qRT PCR analysis showed around 3 fold upregulation of MPS1 in presence of serum. This expression of MPS1 is dependent on Efg1 and is independent of other hyphal regulators like Ras1 and Tpk2. Furthermore, mps1 mutants were also sensitive to oxidative stress. Heterozygous mps1 mutant did not undergo morphological transition and showed 5-Fold reduction in colony forming units in response to macrophage. Thus, the vital checkpoint kinase, Mps1 besides cell division also has a role in morphogenesis and oxidative stress tolerance, in this pathogenic fungus.

  4. Government-industry conference on airborne radioiodine

    International Nuclear Information System (INIS)

    Burchsted, C.A.

    1975-01-01

    The Working Group on Airborne Radioiodine met at AEC Headquarters on March 28, 1974. Dr. Alex Perge gave the introduction for the Division of Waste Management and Transportation, noting the Commission hopes that private industry will take a bigger share in the future in funding and initiating needed research; that there should be a greater effort in the direction of reducing the quantity of material that becomes contaminated as an avenue toward reducing the airborne radioiodine problem, and toward reducing the waste generated to a form suitable for direct storage; and that the Commission must ensure valid bases for future regulations governing airborne releases and contamination. Dr. First discussed the background of the review committee and its outgrowth from the earlier organization meeting. He noted that its function will be the coordination of efforts concerned with the radioiodine problem and the dissemination of information and research data. A major objective of this meeting was to identify subjects for discussion at the Government-Industry Conference of Adsorbers and Adsorbents which will be held in conjunction with the 13th AEC Air Cleaning Conference in August. Mr. Dempsey noted that the gaseous effluent program had been inherited by WMT from the Division of Operational Safety, and that an important function of these continuing meetings of the Working Group will be to guide WMT in the expenditure of funds and assignment of research related to the radioiodine problem. (U.S.)

  5. Somatic mosaicism in families with hemophilia B: 11% of germline mutations originate within a few cell divisions post-fertilization

    Energy Technology Data Exchange (ETDEWEB)

    Knoell, A.; Ketterling, R.P.; Vielhaber, E. [Mayo Clinic/Foundation, Rochester, MN (United States)] [and others

    1994-09-01

    Previous molecular estimates of mosaicism in the dystrophin and other genes generally have focused on the transmission of the mutated allele to two or more children by an individual without the mutation in leukocyte DNA. We have analyzed 414 families with hemophilia B by direct genomic sequencing and haplotype analysis, and have deduced the origin of mutation in 56 families. There was no origin individual who transmitted a mutant allele to more than one child. However, somatic mosaicism was detected by sequence analysis of four origin individuals (3{female} and 1{male}). The sensitivity of this analysis is typically one part in ten. In one additional female who had close to a 50:50 ratio of mutant to normal alleles, three of four noncarrier daughters inherited the haplotype associated with the mutant allele. This highlights a caveat in molecular analysis: a presumptive carrier in a family with sporadic disease does not necessarily have a 50% probability of transmitting the mutant allele to her offspring. After eliminating those families in which mosaicism could not be detected because of a total gene deletion or absence of DNA from a deduced origin individual, 5 of 43 origin individuals exhibited somatic mosaicism at a level that reflects a mutation within the first few cell divisions after fertilization. In one patient, analysis of cervical scrapings and buccal mucosa confirm the generalized distribution of somatic mutation. Are the first few cell divisions post-fertilization highly mutagenic, or do mutations at later divisions also give rise to somatic mosaicism? To address this question, DNA from origin individuals are being analyzed to detect somatic mosaicism at a sensitivity of 1:1000. Single nucleotide primer extension (SNuPE) has been utilized in eight families to date and no mosaicism has been detected. When the remaining 30 samples are analyzed, it will be possible to compare the frequency of somatic mosaicism at 0.1-10% with that of {ge}10%.

  6. 29 CFR 825.401 - Filing a complaint with the Federal Government.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 3 2010-07-01 2010-07-01 false Filing a complaint with the Federal Government. 825.401 Section 825.401 Labor Regulations Relating to Labor (Continued) WAGE AND HOUR DIVISION, DEPARTMENT OF LABOR OTHER LAWS THE FAMILY AND MEDICAL LEAVE ACT OF 1993 Enforcement Mechanisms § 825.401 Filing a...

  7. Phylogeography, salinity adaptations and metabolic potential of the Candidate Division KB1 Bacteria based on a partial single cell genome.

    Directory of Open Access Journals (Sweden)

    Lisa M Nigro

    2016-08-01

    Full Text Available Deep-sea hypersaline anoxic basins (DHABs and other hypersaline environments contain abundant and diverse microbial life that has adapted to these extreme conditions. The bacterial Candidate Division KB1 represents one of several uncultured groups that has been consistently observed in hypersaline microbial diversity studies. Here we report the phylogeography of KB1, its phylogenetic relationships to Candidate Division OP1 Bacteria, and its potential metabolic and osmotic stress adaptations based on a partial single cell amplified genome (SAG of KB1 from Orca Basin, the largest hypersaline seafloor brine basin in the Gulf of Mexico. Our results are consistent with the hypothesis – previously developed based on 14C incorporation experiments with mixed-species enrichments from Mediterranean seafloor brines - that KB1 has adapted its proteins to elevated intracellular salinity, but at the same time KB1 apparently imports glycine betaine; this compatible solute is potentially not limited to osmoregulation but could also serve as a carbon and energy source.

  8. High-Quality Draft Single-Cell Genome Sequence Belonging to the Archaeal Candidate Division SA1, Isolated from Nereus Deep in the Red Sea

    KAUST Repository

    Ngugi, David; Stingl, Ulrich

    2018-01-01

    Candidate division SA1 encompasses a phylogenetically coherent archaeal group ubiquitous in deep hypersaline anoxic brines around the globe. Recently, the genome sequences of two cultivated representatives from hypersaline soda lake sediments were published. Here, we present a single-cell genome sequence from Nereus Deep in the Red Sea that represents a putatively novel family within SA1.

  9. High-Quality Draft Single-Cell Genome Sequence Belonging to the Archaeal Candidate Division SA1, Isolated from Nereus Deep in the Red Sea

    KAUST Repository

    Ngugi, David

    2018-05-09

    Candidate division SA1 encompasses a phylogenetically coherent archaeal group ubiquitous in deep hypersaline anoxic brines around the globe. Recently, the genome sequences of two cultivated representatives from hypersaline soda lake sediments were published. Here, we present a single-cell genome sequence from Nereus Deep in the Red Sea that represents a putatively novel family within SA1.

  10. YeeV is an Escherichia coli toxin that inhibits cell division by targeting the cytoskeleton proteins, FtsZ and MreB.

    Science.gov (United States)

    Tan, Qian; Awano, Naoki; Inouye, Masayori

    2011-01-01

    Toxin-antitoxin (TA) systems of free-living bacteria have recently demonstrated that these toxins inhibit cell growth by targeting essential functions of cellular metabolism. Here we show that YeeV toxin inhibits cell division, leads to a change in morphology and lysis of Escherichia coli cells. YeeV interacts with two essential cytoskeleton proteins, FtsZ and MreB. Purified YeeV inhibits both the GTPase activity and the GTP-dependent polymerization of FtsZ. YeeV also inhibits ATP-dependent polymerization of MreB. Truncated C-terminal deletions of YeeV result in elongation of cells, and a deletion of the first 15 amino acids from the N-terminus of YeeV caused lemon-shaped cell formation. The YeeV toxin is distinct from other well-studied toxins: it directs the binding of two cytoskeletal proteins and inhibits FtsZ and MreB simultaneously. © 2010 Blackwell Publishing Ltd.

  11. Moving epithelia: Tracking the fate of mammalian limbal epithelial stem cells.

    Science.gov (United States)

    Di Girolamo, Nick

    2015-09-01

    Lineage tracing allows the destiny of a stem cell (SC) and its progeny to be followed through time. In order to track their long-term fate, SC must be permanently marked to discern their distribution, division, displacement and differentiation. This information is essential for unravelling the mysteries that govern their replenishing activity while they remain anchored within their niche microenvironment. Modern-day lineage tracing uses inducible genetic recombination to illuminate cells within embryonic, newborn and adult tissues, and the advent of powerful high-resolution microscopy has enabled the behaviour of labelled cells to be monitored in real-time in a living organism. The simple structural organization of the mammalian cornea, including its accessibility and transparency, renders it the ideal tissue to study SC fate using lineage tracing assisted by non-invasive intravital microscopy. Despite more than a century of research devoted to understanding how this tissue is maintained and repaired, many limitations and controversies continue to plague the field, including uncertainties about the specificity of current SC markers, the number of SC within the cornea, their mode of division, their location, and importantly the signals that dictate cell migration. This communication will highlight historical discoveries as well as recent developments in the corneal SC field; more specifically how the progeny of these cells are mobilised to replenish this dynamic tissue during steady-state, disease and transplantation. Also discussed is how insights gleaned from animal studies can be used to advance our knowledge of the fundamental mechanisms that govern modelling and remodelling of the human cornea in health and disease. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Experimental Facilities Division/User Program Division technical progress report 1999-2000

    International Nuclear Information System (INIS)

    2001-01-01

    In October 1999, the two divisions of the Advanced Photon Source (APS), the Accelerator Systems Division (ASD) and the Experimental Facilities Division (XFD), were reorganized into four divisions (see high-level APS organizational chart, Fig. 1.1). In addition to ASD and XFD, two new divisions were created, the APS Operations Division (AOD), to oversee APS operations, and the User Program Division (UPD), to serve the APS user community by developing and maintaining the highest quality user technical and administration support. Previous XFD Progress Reports (ANL/APS/TB-30 and ANL/APS/TB-34) covered a much broader base, including APS user administrative support and what was previously XFD operations (front ends, interlocks, etc.) This Progress Report summarizes the main scientific and technical activities of XFD, and the technical support, research and development (R and D) activities of UPD from October 1998 through November 2000. The report is divided into four major sections, (1) Introduction, (2) SRI-CAT Beamlines, Technical Developments, and Scientific Applications, (3) User Technical Support, and (4) Major Plans for the Future. Sections 2 and 3 describe the technical activities and research accomplishments of the XFD and UPD personnel in supporting the synchrotron radiation instrumentation (SRI) collaborative access team (CAT) and the general APS user community. Also included in this report is a comprehensive list of publications (Appendix 1) and presentations (Appendix 2) by XFD and UPD staff during the time period covered by this report. The organization of section 2, SRI CAT Beamlines, Technical Developments, and Scientific Applications has been made along scientific techniques/disciplines and not ''geographical'' boundaries of the sectors in which the work was performed. Therefore items under the subsection X-ray Imaging and Microfocusing could have been (and were) performed on several different beamlines by staff in different divisions. The management of

  13. Division of atomic physics

    International Nuclear Information System (INIS)

    Kroell, S.

    1994-01-01

    The Division of Atomic Physics, Lund Institute of Technology (LTH), is responsible for the basic physics teaching in all subjects at LTH and for specialized teaching in Optics, Atomic Physics, Atomic and Molecular Spectroscopy and Laser Physics. The Division has research activities in basic and applied optical spectroscopy, to a large extent based on lasers. It is also part of the Physics Department, Lund University, where it forms one of eight divisions. Since the beginning of 1980 the research activities of our division have been centred around the use of lasers. The activities during the period 1991-1992 is described in this progress reports

  14. Technical activities, 1990: Surface Science Division

    International Nuclear Information System (INIS)

    Powell, C.J.

    1991-05-01

    The report summarizes technical activities and accomplishments of the NIST Surface Science Division during Fiscal Year 1990. Overviews are presented of the Division and of its three constituent groups: Surface Dynamical Processes, Thin Films and Interfaces, and Surface Spectroscopies and Standards. These overviews are followed by reports of selected technical accomplishments during the year. A summary is given of Division outputs and interactions that includes lists of publications, talks, committee assignments, seminars (including both Division seminars and Interface Science seminars arranged through the Division), conferences organized, and a standard reference material certified. Finally, lists are given of Division staff and of guest scientists who have worked in the Division during the past year

  15. Microtubule networks for plant cell division

    NARCIS (Netherlands)

    Keijzer, de Jeroen; Mulder, B.M.; Janson, M.E.

    2014-01-01

    During cytokinesis the cytoplasm of a cell is divided to form two daughter cells. In animal cells, the existing plasma membrane is first constricted and then abscised to generate two individual plasma membranes. Plant cells on the other hand divide by forming an interior dividing wall, the so-called

  16. Detection of chromosomal aberrations by fluorescence in situ hybridization in the first three postirradiation divisions of human lymphocytes

    International Nuclear Information System (INIS)

    Boei, J.J.W.A.; Vermeulen, S.; Natarajan, A.T.

    1996-01-01

    Chromosomal aberrations in human lymphocytes were analyzed by fluorescence in situ hybridization (FISH) in the first 3 postirradiation (0 and 2 Gy) divisions. Cells were grown in the presence of BrdU, collected at different sampling times (47, 70 and 91 h) and analyzed using an alphoid centromeric probe and PCR amplified DNA libraries for chromosomes 2 and 8. Following differential staining of sister chromatids, the analyzed cells were identified to be either in the first, second or third mitosis after irradiation. The frequencies of both dicentrics and fragments showed a reduction of about 50% after each cell generation, whereas translocations were more persistent. Cells within the same postirradiation division showed higher aberration frequencies when derived from later sampling times, indicating a delay in progression of aberrant cells. As a result, the frequencies for dicentrics and fragments remained rather constant at different sampling times if the cell cycle parameter was not taken into account. Thus, the average generation time of the lymphocytes had a clear effect on the obtained aberration frequencies. The described method allows the study of the persistence of chromosome damage using the FISH technique during 3 subsequent cell divisions in vitro

  17. Chemical Technology Division, Annual technical report, 1991

    Energy Technology Data Exchange (ETDEWEB)

    1992-03-01

    Highlights of the Chemical Technology (CMT) Division`s activities during 1991 are presented. In this period, CMT conducted research and development in the following areas: (1) electrochemical technology, including advanced batteries and fuel cells; (2) technology for fluidized-bed combustion and coal-fired magnetohydrodynamics; (3) methods for treatment of hazardous and mixed hazardous/radioactive waste; (4) the reaction of nuclear waste glass and spent fuel under conditions expected for an unsaturated repository; (5) processes for separating and recovering transuranic elements from nuclear waste streams; (6) recovery processes for discharged fuel and the uranium blanket in the Integral Fast Reactor (IFR); (7) processes for removal of actinides in spent fuel from commercial water-cooled nuclear reactors and burnup in IFRs; and (8) physical chemistry of selected materials in environments simulating those of fission and fusion energy systems. The Division also conducts basic research in catalytic chemistry associated with molecular energy resources; chemistry of superconducting oxides and other materials of interest with technological application; interfacial processes of importance to corrosion science, catalysis, and high-temperature superconductivity; and the geochemical processes involved in water-rock interactions occurring in active hydrothermal systems. In addition, the Analytical Chemistry Laboratory in CMT provides a broad range of analytical chemistry support services to the technical programs at Argonne National Laboratory (ANL).

  18. PDV2 has a dosage effect on chloroplast division in Arabidopsis.

    Science.gov (United States)

    Chang, Ning; Sun, Qingqing; Li, Yiqiong; Mu, Yajuan; Hu, Jinglei; Feng, Yue; Liu, Xiaomin; Gao, Hongbo

    2017-03-01

    PDV2 has a dosage effect on chloroplast division in Arabidopsis thaliana , but this effect may vary in different plants. Chloroplasts have to be divided as plants grow to maintain an optimized number in the cell. Chloroplasts are divided by protein complexes across the double membranes from the stroma side to the cytosolic side. PDV2 is a chloroplast division protein on the chloroplast outer membrane. It recruits the dynamin-related GTPase ARC5 to the division site. The C-terminus of PDV2 and the C-terminus of ARC6 interact in the intermembrane space, which is important for the localization of PDV2. Previously, it was shown that overexpression of PDV2 can increase the division of chloroplasts in Arabidopsis and moss, so the authors concluded that PDV2 determines the rate of chloroplast division in land plants. PDV2 was also shown to inhibit the GTPase activity of ARC5 by in vitro experiment. These results look to be contradictory. Here, we identified a null allele of PDV2 in Arabidopsis and studied plants with different levels of PDV2. Our results suggested that the chloroplast division phenotype in Arabidopsis is sensitive to the level of PDV2, while this is not the case for ARC6. The level of PDV2 protein is reduced sharply in fast-growing leaves, while the level of ARC6 is not. The levels of PDV2 and ARC6 in several other plant species at different developmental stages were also investigated. The results indicated that their expression pattern varies in different species. Thus, PDV2 is an important positive factor of chloroplast division with an apparent dosage effect in Arabidopsis, but this effect for different chloroplast division proteins in different plants may vary.

  19. The cell wall and cell division gene cluster in the Mra operon of Pseudomonas aeruginosa: cloning, production, and purification of active enzymes.

    Science.gov (United States)

    Azzolina, B A; Yuan, X; Anderson, M S; El-Sherbeini, M

    2001-04-01

    We have cloned the Pseudomonas aeruginosa cell wall biosynthesis and cell division gene cluster that corresponds to the mra operon in the 2-min region of the Escherichia coli chromosome. The organization of the two chromosomal regions in P. aeruginosa and E. coli is remarkably similar with the following gene order: pbp3/pbpB, murE, murF, mraY, murD, ftsW, murG, murC, ddlB, ftsQ, ftsA, ftsZ, and envA/LpxC. All of the above P. aeruginosa genes are transcribed from the same strand of DNA with very small, if any, intragenic regions, indicating that these genes may constitute a single operon. All five amino acid ligases, MurC, MurD, MurE, MurF, and DdlB, in addition to MurG and MraY were cloned in expression vectors. The four recombinant P. aeruginosa Mur ligases, MurC, MurD, MurE, and MurF were overproduced in E. coli and purified as active enzymes. Copyright 2001 Academic Press.

  20. A parasitic nematode releases cytokinin that controls cell division and orchestrates feeding site formation in host plants.

    Science.gov (United States)

    Siddique, Shahid; Radakovic, Zoran S; De La Torre, Carola M; Chronis, Demosthenis; Novák, Ondřej; Ramireddy, Eswarayya; Holbein, Julia; Matera, Christiane; Hütten, Marion; Gutbrod, Philipp; Anjam, Muhammad Shahzad; Rozanska, Elzbieta; Habash, Samer; Elashry, Abdelnaser; Sobczak, Miroslaw; Kakimoto, Tatsuo; Strnad, Miroslav; Schmülling, Thomas; Mitchum, Melissa G; Grundler, Florian M W

    2015-10-13

    Sedentary plant-parasitic cyst nematodes are biotrophs that cause significant losses in agriculture. Parasitism is based on modifications of host root cells that lead to the formation of a hypermetabolic feeding site (a syncytium) from which nematodes withdraw nutrients. The host cell cycle is activated in an initial cell selected by the nematode for feeding, followed by activation of neighboring cells and subsequent expansion of feeding site through fusion of hundreds of cells. It is generally assumed that nematodes manipulate production and signaling of the plant hormone cytokinin to activate cell division. In fact, nematodes have been shown to produce cytokinin in vitro; however, whether the hormone is secreted into host plants and plays a role in parasitism remained unknown. Here, we analyzed the spatiotemporal activation of cytokinin signaling during interaction between the cyst nematode, Heterodera schachtii, and Arabidopsis using cytokinin-responsive promoter:reporter lines. Our results showed that cytokinin signaling is activated not only in the syncytium but also in neighboring cells to be incorporated into syncytium. An analysis of nematode infection on mutants that are deficient in cytokinin or cytokinin signaling revealed a significant decrease in susceptibility of these plants to nematodes. Further, we identified a cytokinin-synthesizing isopentenyltransferase gene in H. schachtii and show that silencing of this gene in nematodes leads to a significant decrease in virulence due to a reduced expansion of feeding sites. Our findings demonstrate the ability of a plant-parasitic nematode to synthesize a functional plant hormone to manipulate the host system and establish a long-term parasitic interaction.

  1. The cell cycle of the planctomycete Gemmata obscuriglobus with respect to cell compartmentalization

    Directory of Open Access Journals (Sweden)

    Fuerst John A

    2009-01-01

    Full Text Available Abstract Background Gemmata obscuriglobus is a distinctive member of the divergent phylum Planctomycetes, all known members of which are peptidoglycan-less bacteria with a shared compartmentalized cell structure and divide by a budding process. G. obscuriglobus in addition shares the unique feature that its nucleoid DNA is surrounded by an envelope consisting of two membranes forming an analogous structure to the membrane-bounded nucleoid of eukaryotes and therefore G. obscuriglobus forms a special model for cell biology. Draft genome data for G. obscuriglobus as well as complete genome sequences available so far for other planctomycetes indicate that the key bacterial cell division protein FtsZ is not present in these planctomycetes, so the cell division process in planctomycetes is of special comparative interest. The membrane-bounded nature of the nucleoid in G. obscuriglobus also suggests that special mechanisms for the distribution of this nuclear body to the bud and for distribution of chromosomal DNA might exist during division. It was therefore of interest to examine the cell division cycle in G. obscuriglobus and the process of nucleoid distribution and nuclear body formation during division in this planctomycete bacterium via light and electron microscopy. Results Using phase contrast and fluorescence light microscopy, and transmission electron microscopy, the cell division cycle of G. obscuriglobus was determined. During the budding process, the bud was formed and developed in size from one point of the mother cell perimeter until separation. The matured daughter cell acted as a new mother cell and started its own budding cycle while the mother cell can itself initiate budding repeatedly. Fluorescence microscopy of DAPI-stained cells of G. obscuriglobus suggested that translocation of the nucleoid and formation of the bud did not occur at the same time. Confocal laser scanning light microscopy applied to cells stained for membranes as

  2. E-Division activities report

    International Nuclear Information System (INIS)

    Barschall, H.H.

    1984-07-01

    E (Experimental Physics) Division carries out basic and applied research in atomic and nuclear physics, in materials science, and in other areas related to the missions of the Laboratory. Some of the activities are cooperative efforts with other divisions of the Laboratory, and, in a few cases, with other laboratories. Many of the experiments are directly applicable to problems in weapons and energy, some have only potential applied uses, and others are in pure physics. This report presents abstracts of papers published by E (Experimental Physics) Division staff members between July 1983 and June 1984. In addition, it lists the members of the scientific staff of the division, including visitors and students, and some of the assignments of staff members on scientific committees. A brief summary of the budget is included

  3. Progress report of Applied Physics Division. 1 October 1980 - 30 June 1981. Acting Division Chief - Dr. J. Parry

    International Nuclear Information System (INIS)

    2004-01-01

    In September 1980, the Commission approved a reorganization of Physics Division, Engineering Research Division and Instrumentation and Control Division to form two new research divisions to be known as Applied Physics Division and Nuclear Technology Division. The Applied Physics Division will be responsible for applied science programs, particularly those concerned with nuclear techniques. The Division is organized as four sections with the following responsibilities: (1) Nuclear Applications and Energy Studies Section. Program includes studies in nuclear physics, nuclear applications, ion implantation and neutron scattering. (2) Semiconductor and Radiation Physics Section. Studies in semiconductor radiation detectors, radiation standards and laser applications. (3) Electronic Systems Section. This includes systems analysis, digital systems, instrument design, project instrumentation and instrument maintenance. (4) Fusion Physics Section. This covers work carried out by staff currently attached to university groups (author)

  4. Lunatic fringe-mediated Notch signaling regulates adult hippocampal neural stem cell maintenance.

    Science.gov (United States)

    Semerci, Fatih; Choi, William Tin-Shing; Bajic, Aleksandar; Thakkar, Aarohi; Encinas, Juan Manuel; Depreux, Frederic; Segil, Neil; Groves, Andrew K; Maletic-Savatic, Mirjana

    2017-07-12

    Hippocampal neural stem cells (NSCs) integrate inputs from multiple sources to balance quiescence and activation. Notch signaling plays a key role during this process. Here, we report that Lunatic fringe ( Lfng), a key modifier of the Notch receptor, is selectively expressed in NSCs. Further, Lfng in NSCs and Notch ligands Delta1 and Jagged1, expressed by their progeny, together influence NSC recruitment, cell cycle duration, and terminal fate. We propose a new model in which Lfng-mediated Notch signaling enables direct communication between a NSC and its descendants, so that progeny can send feedback signals to the 'mother' cell to modify its cell cycle status. Lfng-mediated Notch signaling appears to be a key factor governing NSC quiescence, division, and fate.

  5. Division Quilts: A Measurement Model

    Science.gov (United States)

    Pratt, Sarah S.; Lupton, Tina M.; Richardson, Kerri

    2015-01-01

    As teachers seek activities to assist students in understanding division as more than just the algorithm, they find many examples of division as fair sharing. However, teachers have few activities to engage students in a quotative (measurement) model of division. Efraim Fischbein and his colleagues (1985) defined two types of whole-number…

  6. 75 FR 67433 - Waiver of Restriction on Assistance to the Government of Saudi Arabia

    Science.gov (United States)

    2010-11-02

    ... DEPARTMENT OF STATE [Public Notice: 7220] Waiver of Restriction on Assistance to the Government of Saudi Arabia Pursuant to Section 7041 of the Department of State, Foreign Operations, and Related Programs Appropriations Act, 2010 (Division F, Pub. L. 111-117) (``the Act''), I hereby determine that it...

  7. Instrumentation and Controls Division progress report for the period July 1, 1986 to June 30, 1988

    International Nuclear Information System (INIS)

    Klobe, L.E.

    1988-12-01

    The Instrumentation and Controls (IandC) Division of Oak Ridge National Laboratory (ORNL) performs basic and applied instrumentation and controls research, development and design engineering, specialized instrument design and fabrication, and maintenance services for instruments, electronics, and computers. The IandC Division is one of the largest RandD organizations of its type among government laboratories, and it exists as the result of an organizational strategy to integrate ORNL's instrumentation and controls-related disciplines into one dedicated functional organization to increase the Laboratory's expertise and capabilities in these rapidly expanding, innovative areas of technology. The Division participates in the programs and projects of ORNL by applying its expertise and capabilities in concert with other divisions to perform basic research and mission-oriented technology development. Many of the Division's RandD tasks that are a part of a larger ORNL program are of sufficient scope that the IandC effort constitutes a separate program element with direct funding and management responsibility within the Division. The activities of IandC include performance of an RandD task in IandC facilities, the participation of from one of many IandC engineers and scientists in a multidisciplinary team working in a specific research area or development project, design and fabrication of a special instrument or instrumentation system, or a few hours of maintenance service. In its support and maintenance work, the role of the IandC Division is to provide a level of expertise appropriate to complete a job successfully at minimum overall cost and time schedule---a role which involves IandC in almost all ORNL activities

  8. Instrumentation and Controls Division progress report for the period July 1, 1986 to June 30, 1988

    Energy Technology Data Exchange (ETDEWEB)

    Klobe, L.E. (ed.)

    1988-12-01

    The Instrumentation and Controls (IandC) Division of Oak Ridge National Laboratory (ORNL) performs basic and applied instrumentation and controls research, development and design engineering, specialized instrument design and fabrication, and maintenance services for instruments, electronics, and computers. The IandC Division is one of the largest RandD organizations of its type among government laboratories, and it exists as the result of an organizational strategy to integrate ORNL's instrumentation and controls-related disciplines into one dedicated functional organization to increase the Laboratory's expertise and capabilities in these rapidly expanding, innovative areas of technology. The Division participates in the programs and projects of ORNL by applying its expertise and capabilities in concert with other divisions to perform basic research and mission-oriented technology development. Many of the Division's RandD tasks that are a part of a larger ORNL program are of sufficient scope that the IandC effort constitutes a separate program element with direct funding and management responsibility within the Division. The activities of IandC include performance of an RandD task in IandC facilities, the participation of from one of many IandC engineers and scientists in a multidisciplinary team working in a specific research area or development project, design and fabrication of a special instrument or instrumentation system, or a few hours of maintenance service. In its support and maintenance work, the role of the IandC Division is to provide a level of expertise appropriate to complete a job successfully at minimum overall cost and time schedule---a role which involves IandC in almost all ORNL activities.

  9. Comparison of Concussion Rates Between NCAA Division I and Division III Men's and Women's Ice Hockey Players.

    Science.gov (United States)

    Rosene, John M; Raksnis, Bryan; Silva, Brie; Woefel, Tyler; Visich, Paul S; Dompier, Thomas P; Kerr, Zachary Y

    2017-09-01

    Examinations related to divisional differences in the incidence of sports-related concussions (SRC) in collegiate ice hockey are limited. To compare the epidemiologic patterns of concussion in National Collegiate Athletic Association (NCAA) ice hockey by sex and division. Descriptive epidemiology study. A convenience sample of men's and women's ice hockey teams in Divisions I and III provided SRC data via the NCAA Injury Surveillance Program during the 2009-2010 to 2014-2015 academic years. Concussion counts, rates, and distributions were examined by factors including injury activity and position. Injury rate ratios (IRRs) and injury proportion ratios (IPRs) with 95% confidence intervals (CIs) were used to compare concussion rates and distributions, respectively. Overall, 415 concussions were reported for men's and women's ice hockey combined. The highest concussion rate was found in Division I men (0.83 per 1000 athlete-exposures [AEs]), followed by Division III women (0.78/1000 AEs), Division I women (0.65/1000 AEs), and Division III men (0.64/1000 AEs). However, the only significant IRR was that the concussion rate was higher in Division I men than Division III men (IRR = 1.29; 95% CI, 1.02-1.65). The proportion of concussions from checking was higher in men than women (28.5% vs 9.4%; IPR = 3.02; 95% CI, 1.63-5.59); however, this proportion was higher in Division I women than Division III women (18.4% vs 1.8%; IPR = 10.47; 95% CI, 1.37-79.75). The proportion of concussions sustained by goalkeepers was higher in women than men (14.2% vs 2.9%; IPR = 4.86; 95% CI, 2.19-10.77), with findings consistent within each division. Concussion rates did not vary by sex but differed by division among men. Checking-related concussions were less common in women than men overall but more common in Division I women than Division III women. Findings highlight the need to better understand the reasons underlying divisional differences within men's and women's ice hockey and the

  10. Enteral peptide formulas inhibit radiation induced enteritis and apoptosis in intestinal epithelial cells and suppress the expression and function of Alzheimer's and cell division control gene products

    International Nuclear Information System (INIS)

    Cope, F.O.; Issinger, O.G.; McArdle, A.H.; Shapiro, J.; Tomei, L.D.

    1991-01-01

    Studies have shown that patients receiving enteral peptide formulas prior to irradiation have a significantly reduced incidence of enteritis and express a profound increase in intestinal cellularity. Two conceptual approaches were taken to describe this response. First was the evaluation in changes in programmed intestinal cell death and secondly the evaluation of a gene product controlling cell division cycling. This study provided a relationship between the ratio of cell death to cell formulations. The results indicate that in the canine and murine models, irradiation induces expression of the Alzheimer's gene in intestinal crypt cells, while the incidence of apoptosis in apical cells is significantly increased. The use of peptide enteral formulations suppresses the expression of the Alzheimer's gene in crypt cells, while apoptosis is eliminated in the apical cells of the intestine. Concomitantly, enteral peptide formulations suppress the function of the CK-II gene product in the basal and baso-lateral cells of the intestine. These data indicate that although the mitotic index is significantly reduced in enterocytes, this phenomenon alone is not sufficient to account for the peptide-induced radio-resistance of the intestine. The data also indicate a significant reduction of normal apoptosis in the upper lateral and apical cells of the intestinal villi. Thus, the ratio of cell death to cell replacement is significantly decreased resulting in an increase in villus height and hypertrophy of the apical villus cells. Thus, peptide solutions should be considered as an adjunct treatment both in radio- and chemotherapy

  11. Modelling of post-irradiation accelerated repopulation in squamous cell carcinomas

    International Nuclear Information System (INIS)

    Marcu, L; Doorn, T van; Olver, I

    2004-01-01

    The mechanisms postulated to be responsible for the accelerated repopulation of squamous cell carcinomas during radiotherapy are the loss of asymmetry of stem cell division, acceleration of stem cell division, abortive division and/or recruitment of the non-cycling cell with proliferative capacity. Although accelerated repopulation was observed with recruitment and accelerated cell cycles, it was not sufficient to cause an observable change to the survival curve. However, modelling the loss of asymmetry in stem cell division has reshaped the curve with a 'growth' shoulder. Cell recruitment was not found to be a major contributor to accelerated tumour repopulation. A more significant contribution was provided through the multiplication of surviving tumour stem cells during radiotherapy, by reducing their cell cycle time, and due to loss of asymmetry of stem cell division

  12. Chlamydia trachomatis protein CT009 is a structural and functional homolog to the key morphogenesis component RodZ and interacts with division septal plane localized MreB

    OpenAIRE

    Kemege, Kyle E.; Hickey, John M.; Barta, Michael L.; Wickstrum, Jason; Balwalli, Namita; Lovell, Scott; Battaile, Kevin P.; Hefty, P. Scott

    2014-01-01

    Cell division in Chlamydiae is poorly understood as apparent homologs to most conserved bacterial cell division proteins are lacking and presence of elongation (rod shape) associated proteins indicate non-canonical mechanisms may be employed. The rod-shape determining protein MreB has been proposed as playing a unique role in chlamydial cell division. In other organisms, MreB is part of an elongation complex that requires RodZ for proper function. A recent study reported that the protein enco...

  13. Chemical Technology Division annual technical report, 1985

    International Nuclear Information System (INIS)

    1986-04-01

    Highlights of the Chemical Technology (CMT) Division's activities during 1985 are presented. In this period, CMT conducted research and development in areas that include the following: (1) advanced batteries - mainly lithium-alloy/metal sulfide and sodium/sulfur; (2) advanced fuel cells with molten carbonate or solid oxide electrolytes; (3) corrosion-protective coatings for high-strength steel; (4) coal utilization, including the heat and seed recovery technology for coal-fired magnetohydrodynamics plants and the technology for fluidized-bed combustion; (5) methodologies for recovery of energy from municipal waste; (6) nuclear technology related to waste management, the recovery processes for discharged fuel and the uranium blanket in a sodium-cooled fast reactor, and proof of breeding in a light water breeder reactor; and (7) physical chemistry of selected materials in environments simulating those of fission and fusion energy systems. The Division also has a program in basic chemistry research in the areas of catalytic hydrogenation and catalytic oxidation; materials chemistry for associated and ordered solutions at high temperatures; interfacial processes of importance to corrosion science, surface science, and catalysis; the thermochemistry of zeolites and related silicates; and the geochemical processes responsible for trace-element migration within the earth's crust. The Division continued to be the major user of the technical support provided by the Analytical Chemistry Laboratory at ANL

  14. Chemical Technology Division annual technical report, 1994

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-06-01

    Highlights of the Chemical Technology (CMT) Division`s activities during 1994 are presented. In this period, CMT conducted research and development in the following areas: (1) electrochemical technology, including advanced batteries and fuel cells; (2) technology for fluidized-bed combustion; (3) methods for treatment of hazardous waste and mixed hazardous/radioactive waste; (4) the reaction of nuclear waste glass and spent fuel under conditions expected for an unsaturated repository; (5) processes for separating and recovering transuranic elements from waste streams, concentrating radioactive waste streams with advanced evaporator technology, and producing {sup 99}Mo from low-enriched uranium for medical applications; (6) electrometallurgical treatment of the many different types of spent nuclear fuel in storage at Department of Energy sites; and (8) physical chemistry of selected materials in environments simulating those of fission and fusion energy systems. The Division also conducts basic research in catalytic chemistry associated with molecular energy resources and novel ceramic precursors; materials chemistry of superconducting oxides, electrified metal/solution interfaces, molecular sieve structures, and impurities in scrap copper and steel; and the geochemical processes involved in mineral/fluid interfaces and water-rock interactions occurring in active hydrothermal systems. In addition, the Analytical Chemistry Laboratory in CMT provides a broad range of analytical chemistry support services to the technical programs at Argonne National Laboratory (ANL).

  15. Dose dependency of the frequency of micronucleated binucleated clone cells and of division related median clone sizes difference. Pt. 2

    International Nuclear Information System (INIS)

    Hagemann, G,; Kreczik, A.; Treichel, M.

    1996-01-01

    Following irradiation of the progenitor cells the clone growth of CHO cells decreases as a result of cell losses. Lethally acting expressions of micronuclei are produced by heritable lethal mutations. The dependency of the frequency of micronucleated binucleated clone cells and of the median clone sizes difference on the radiation dose was measured and compared to non-irradiated controls. Using the cytokinesis-block-micronucleus-method binucleated cells with micronuclei were counted as ratio of all binucleated cells within a clone size distribution. This ratio (shortened: micronucleus yield) was determined for all clone size distributions, which had been exposed to different irradiation doses and incubation times. The micronucleus yields were compared to the corresponding median clone sizes differences. The micronucleus yield is linearly dependent on the dose and is independent of the incubation time. The same holds true for the division related median clone sizes difference, which as a result is also linearly dependent on the micronucleus yield. Due to the inevitably errors of the cell count of micronucleated binucleated cells, an automatic measurement of the median clone sizes differences is the preferred method for evaluation of cellular radiation sensitivity for heritable lethal mutations. This value should always be determined in addition, if clone survival fractions are used as predictive test because it allows for an estimation of the remission probability of surviving cells. (orig.) [de

  16. Division site positioning in bacteria: one size does not fit all.

    Directory of Open Access Journals (Sweden)

    Leigh Graham Monahan

    2014-02-01

    Full Text Available Spatial regulation of cell division in bacteria has been a focus of research for decades. It has been well studied in two model rod-shaped organisms, Escherichia coli and Bacillus subtilis, with the general belief that division site positioning occurs as a result of the combination of two negative regulatory systems, Min and nucleoid occlusion. These systems influence division by preventing the cytokinetic Z ring from forming anywhere other than midcell. However, evidence is accumulating for the existence of additional mechanisms that are involved in controlling Z ring positioning both in these organisms and in several other bacteria. In some cases the decision of where to divide is solved by variations on a common evolutionary theme, and in others completely different proteins and mechanisms are involved. Here we review the different ways bacteria solve the problem of finding the right place to divide. It appears that a one-size-fits-all model does not apply, and that individual species have adapted a division-site positioning mechanism that best suits their lifestyle, environmental niche and mode of growth to ensure equal partitioning of DNA for survival of the next generation.

  17. Modes of overinitiation, dnaA gene expression, and inhibition of cell division in a novel cold-sensitive hda mutant of Escherichia coli.

    Science.gov (United States)

    Fujimitsu, Kazuyuki; Su'etsugu, Masayuki; Yamaguchi, Yoko; Mazda, Kensaku; Fu, Nisi; Kawakami, Hironori; Katayama, Tsutomu

    2008-08-01

    The chromosomal replication cycle is strictly coordinated with cell cycle progression in Escherichia coli. ATP-DnaA initiates replication, leading to loading of the DNA polymerase III holoenzyme. The DNA-loaded form of the beta clamp subunit of the polymerase binds the Hda protein, which promotes ATP-DnaA hydrolysis, yielding inactive ADP-DnaA. This regulation is required to repress overinitiation. In this study, we have isolated a novel cold-sensitive hda mutant, the hda-185 mutant. The hda-185 mutant caused overinitiation of chromosomal replication at 25 degrees C, which most likely led to blockage of replication fork progress. Consistently, the inhibition of colony formation at 25 degrees C was suppressed by disruption of the diaA gene, an initiation stimulator. Disruption of the seqA gene, an initiation inhibitor, showed synthetic lethality with hda-185 even at 42 degrees C. The cellular ATP-DnaA level was increased in an hda-185-dependent manner. The cellular concentrations of DnaA protein and dnaA mRNA were comparable at 25 degrees C to those in a wild-type hda strain. We also found that multiple copies of the ribonucleotide reductase genes (nrdAB or nrdEF) or dnaB gene repressed overinitiation. The cellular levels of dATP and dCTP were elevated in cells bearing multiple copies of nrdAB. The catalytic site within NrdA was required for multicopy suppression, suggesting the importance of an active form of NrdA or elevated levels of deoxyribonucleotides in inhibition of overinitiation in the hda-185 cells. Cell division in the hda-185 mutant was inhibited at 25 degrees C in a LexA regulon-independent manner, suggesting that overinitiation in the hda-185 mutant induced a unique division inhibition pathway.

  18. Modes of Overinitiation, dnaA Gene Expression, and Inhibition of Cell Division in a Novel Cold-Sensitive hda Mutant of Escherichia coli▿

    Science.gov (United States)

    Fujimitsu, Kazuyuki; Su'etsugu, Masayuki; Yamaguchi, Yoko; Mazda, Kensaku; Fu, Nisi; Kawakami, Hironori; Katayama, Tsutomu

    2008-01-01

    The chromosomal replication cycle is strictly coordinated with cell cycle progression in Escherichia coli. ATP-DnaA initiates replication, leading to loading of the DNA polymerase III holoenzyme. The DNA-loaded form of the β clamp subunit of the polymerase binds the Hda protein, which promotes ATP-DnaA hydrolysis, yielding inactive ADP-DnaA. This regulation is required to repress overinitiation. In this study, we have isolated a novel cold-sensitive hda mutant, the hda-185 mutant. The hda-185 mutant caused overinitiation of chromosomal replication at 25°C, which most likely led to blockage of replication fork progress. Consistently, the inhibition of colony formation at 25°C was suppressed by disruption of the diaA gene, an initiation stimulator. Disruption of the seqA gene, an initiation inhibitor, showed synthetic lethality with hda-185 even at 42°C. The cellular ATP-DnaA level was increased in an hda-185-dependent manner. The cellular concentrations of DnaA protein and dnaA mRNA were comparable at 25°C to those in a wild-type hda strain. We also found that multiple copies of the ribonucleotide reductase genes (nrdAB or nrdEF) or dnaB gene repressed overinitiation. The cellular levels of dATP and dCTP were elevated in cells bearing multiple copies of nrdAB. The catalytic site within NrdA was required for multicopy suppression, suggesting the importance of an active form of NrdA or elevated levels of deoxyribonucleotides in inhibition of overinitiation in the hda-185 cells. Cell division in the hda-185 mutant was inhibited at 25°C in a LexA regulon-independent manner, suggesting that overinitiation in the hda-185 mutant induced a unique division inhibition pathway. PMID:18502852

  19. Asymmetric division and differential gene expression during a bacterial developmental program requires DivIVA.

    Directory of Open Access Journals (Sweden)

    Prahathees Eswaramoorthy

    2014-08-01

    Full Text Available Sporulation in the bacterium Bacillus subtilis is a developmental program in which a progenitor cell differentiates into two different cell types, the smaller of which eventually becomes a dormant cell called a spore. The process begins with an asymmetric cell division event, followed by the activation of a transcription factor, σF, specifically in the smaller cell. Here, we show that the structural protein DivIVA localizes to the polar septum during sporulation and is required for asymmetric division and the compartment-specific activation of σF. Both events are known to require a protein called SpoIIE, which also localizes to the polar septum. We show that DivIVA copurifies with SpoIIE and that DivIVA may anchor SpoIIE briefly to the assembling polar septum before SpoIIE is subsequently released into the forespore membrane and recaptured at the polar septum. Finally, using super-resolution microscopy, we demonstrate that DivIVA and SpoIIE ultimately display a biased localization on the side of the polar septum that faces the smaller compartment in which σF is activated.

  20. Breaking down the barriers to commercialization of fuel cells in transportation through Government - industry R&D programs

    Energy Technology Data Exchange (ETDEWEB)

    Chalk, S.G. [Dept. of Energy, Washington, DC (United States); Venkateswaran, S.R. [Energetics, Inc., Columbia, MD (United States)

    1996-12-31

    PEM fuel cell technology is rapidly emerging as a viable propulsion alternative to the internal combustion engine. Fuel cells offer the advantages of low emissions, high efficiency, fuel flexibility, quiet and continuous operation, and modularity. Over the last decade, dramatic advances have been achieved in the performance and cost of PEM fuel cell technologies for automotive applications. However, significant technical barriers remain to making fuel cell propulsion systems viable alternatives to the internal combustion engine. This paper focuses on the progress achieved and remaining technical barriers while highlighting Government-industry R&D efforts that are accelerating fuel cell technology toward commercialization.

  1. 77 FR 40586 - Coastal Programs Division

    Science.gov (United States)

    2012-07-10

    ... DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration Coastal Programs Division AGENCY: Coastal Programs Division, Office of Ocean and Coastal Resource Management, National Ocean.... FOR FURTHER INFORMATION CONTACT: Kerry Kehoe, Coastal Programs Division (NORM/3), Office of Ocean and...

  2. Biology Division progress report for the period of October 1, 1986--September 30, 1988

    Energy Technology Data Exchange (ETDEWEB)

    1988-09-01

    The Biology Division of the Oak Ridge National Laboratory is one component of the Department of Energy's intramural program in life sciences. Accordingly, /approximately/75% of the Division's total budget is derived from the Department of Energy through its Office of Health and Environmental Research. With respect to experimental biology, the congressionally mandated mission of this Office is to study adverse health effects of energy production and utilization. Within this stated broad mission, common themes among the research programs of the Biology Division are interactions of animals, cells, and molecules with their respective environments. Investigations focus on genetic and somatic effects of radiation and chemicals. Goals include identification and quantification of these effects, elucidation of pathways by which the effects are expressed, assessment of risks associated with radiation and chemical exposures, and establishment of strategies for extrapolation of risk data from animals to humans. Concurrent basic studies in genetics, biochemistry, molecular biology, and cell biology illuminate normal life processes as prerequisites to comprehending mutagenic and carcinogenic effects of environmental agents.

  3. Origin and evolution of binucleated cells and binucleated cells with micronuclei in cisplatin-treated CHO cultures.

    Science.gov (United States)

    Rodilla, V

    1993-08-01

    It has recently been described that cisplatin is an agent able to induce binucleated cells (BC) in cultured CHO cells. Both the origin and the significance of those cells within a population are unknown although several hypothesis have been suggested such as blocking of cytokinesis or cell fusion. Using interval photography we have found that at least two mechanisms are involved in the production of BC. These cells can arise in a culture as a result of an incomplete process of cell division, i.e. karyokinesis with incomplete cytokinesis or as a result of the mitotic division of a pre-existent BC. The mitotic division of a BC can give rise to different types of daughter cells. These BC sometimes enter mitosis but fail to divide and as a consequence they remain BC. When the process of division is successful (in the vast majority of cases), the results that have been found are either two mononucleated cells or one mononucleated and one binucleated cell. The possible implications and significance of BC and BC with micronuclei in a given population are discussed.

  4. Biology Division progress report for period of October 1, 1988--September 30, 1989

    Energy Technology Data Exchange (ETDEWEB)

    1990-02-01

    The Biology Division of the Oak Ridge National Laboratory is one component of the Department of Energy's intramural program in life sciences. With respect to experimental biology, the congressionally mandated mission of this Office is to study adverse health effects of energy production and utilization. Within this stated broad mission, common themes among the research programs of the Biology Division are interactions of animals, cells, and molecules with their respective environments. Investigations focus on genetic and somatic effects of radiation and chemicals. Goals include identification and quantification of these effects, elucidation of pathways by which the effects are expressed, assessment of risks associated with radiation and chemical exposures, and establishment of strategies for extrapolation of risk data from animals to humans. Concurrent basic studies in genetics, biochemistry, molecular biology, and cell biology illuminate normal life processes as prerequisites to comprehending mutagenic and carcinogenic effects of environmental agents. This Progress Report is intended to provide both broad perspectives of the Division's research programs and synopses of recent achievements. Readers are invited to contact individual principal investigators for more detailed information, including reprints of publications. 120 refs.

  5. Theoretical Division progress report

    International Nuclear Information System (INIS)

    Cooper, N.G.

    1979-04-01

    This report presents highlights of activities in the Theoretical (T) Division from October 1976-January 1979. The report is divided into three parts. Part I presents an overview of the Division: its unique function at the Los Alamos Scientific Laboratory (LASL) and within the scientific community as a whole; the organization of personnel; the main areas of research; and a survey of recent T-Division initiatives. This overview is followed by a survey of the 13 groups within the Division, their main responsibilities, interests, and expertise, consulting activities, and recent scientific accomplisments. The remainder of the report, Parts II and III, is devoted to articles on selected research activities. Recent efforts on topics of immediate interest to energy and weapons programs at LASL and elsewhere are described in Part II, Major National Programs. Separate articles present T-Divison contributions to weapons research, reactor safety and reactor physics research, fusion research, laser isotope separation, and other energy research. Each article is a compilation of independent projects within T Division, all related to but addressing different aspects of the major program. Part III is organized by subject discipline, and describes recent scientific advances of fundamental interest. An introduction, defining the scope and general nature of T-Division efforts within a given discipline, is followed by articles on the research topics selected. The reporting is done by the scientists involved in the research, and an attempt is made to communicate to a general audience. Some data are given incidentally; more technical presentations of the research accomplished may be found among the 47 pages of references. 110 figures, 5 tables

  6. Fusion energy division computer systems network

    International Nuclear Information System (INIS)

    Hammons, C.E.

    1980-12-01

    The Fusion Energy Division of the Oak Ridge National Laboratory (ORNL) operated by Union Carbide Corporation Nuclear Division (UCC-ND) is primarily involved in the investigation of problems related to the use of controlled thermonuclear fusion as an energy source. The Fusion Energy Division supports investigations of experimental fusion devices and related fusion theory. This memo provides a brief overview of the computing environment in the Fusion Energy Division and the computing support provided to the experimental effort and theory research

  7. 78 FR 23903 - Proposed Information Collection; Comment Request; Quarterly Summary of State and Local Government...

    Science.gov (United States)

    2013-04-23

    ... Cheryl Lee, Chief, State Finance and Tax Statistics Branch, Governments Division, U.S. Census Bureau... economic research and comparative studies of governmental finances. Tax collection data are used to measure...) ways to enhance the quality, utility, and clarity of the information to be collected; and (d) ways to...

  8. Division of Information Technology - Overview

    International Nuclear Information System (INIS)

    Szlachciak, J.

    2008-01-01

    Full text: The Division of Information Technology continued its service-oriented activities in 2007. Our main duty was a day-to-day support to all units in the Institute in IT related matters. One of our tasks was the acquiring, configuration and delivery of new computer equipment to our users. We prepared technical specification for several biddings and we verified bids received from the point of view of correctness. Due to financial support from our government, we purchased about one-fourth of our existing computer equipment. This hardware has partially replaced the old units and partially supported our new staff. Implemented at the end of 2006 the Scientific Activity Database has continued its operation and has been extended by several useful reports and fields containing important information. We started preliminary activities related to implementation of video conferencing services in our Institute. Apart of taking part in seminars and consulting several companies, we have managed to transmit a few scientific seminars from Warsaw to our department in Lodz. (author)

  9. Comparison of tumor biology of two distinct cell sub-populations in lung cancer stem cells.

    Science.gov (United States)

    Wang, Jianyu; Sun, Zhiwei; Liu, Yongli; Kong, Liangsheng; Zhou, Shixia; Tang, Junlin; Xing, Hongmei Rosie

    2017-11-14

    Characterization of the stem-like properties of cancer stem cells (CSCs) remain indirect and qualitative, especially the ability of CSCs to undergo asymmetric cell division for self renewal and differentiation, a unique property of cells of stem origin. It is partly due to the lack of stable cellular models of CSCs. In this study, we developed a new approach for CSC isolation and purification to derive a CSC-enriched cell line (LLC-SE). By conducting five consecutive rounds of single cell cloning using the LLC-SE cell line, we obtained two distinct sub-population of cells within the Lewis lung cancer CSCs that employed largely symmetric division for self-renewal (LLC-SD) or underwent asymmetric division for differentiation (LLC-ASD). LLC-SD and LLC-ASD cell lines could be stably passaged in culture and be distinguished by cell morphology, stem cell marker, spheroid formation and subcutaneous tumor initiation efficiency, as well as orthotopic lung tumor growth, progression and survival. The ability LLC-ASD cells to undergo asymmetric division was visualized and quantified by the asymmetric segregation of labeled BrdU and NUMB to one of the two daughter cells in anaphase cell division. The more stem-like LLC-SD cells exhibited higher capacity for tumorigenesis and progression and shorter survival. As few as 10 LLC-SD could initiate subcutaneous tumor growth when transplanted to the athymic mice. Collectively, these observations suggest that the SD-type of cells appear to be on the top of the hierarchical order of the CSCs. Furthermore, they have lead to generated cellular models of CSC self-renewal for future mechanistic investigations.

  10. Symmetry breaking in human neuroblastoma cells

    Science.gov (United States)

    Izumi, Hideki; Kaneko, Yasuhiko

    2014-01-01

    Asymmetric cell division (ACD) is a characteristic of cancer stem cells, which exhibit high malignant potential. However, the cellular mechanisms that regulate symmetric (self-renewal) and asymmetric cell divisions are mostly unknown. Using human neuroblastoma cells, we found that the oncosuppressor protein tripartite motif containing 32 (TRIM32) positively regulates ACD. PMID:27308367

  11. Chemical Engineering Division annual technical report, 1980

    International Nuclear Information System (INIS)

    Burris, L.; Webster, D.S.; Barney, D.L.; Cafasso, F.A.; Steindler, M.J.

    1981-06-01

    Highlights of the Chemical Engineering (CEN) Division's activities during 1980 are presented. In this period, CEN conducted research and development in the following areas: (1) rechargeable lithium-aluminum/iron sulfide batteries for electric vehicles and other applications; (2) ambient-temperature batteries - improved lead-acid, nickel/zinc, and nickel/iron - for electric vehicles; (3) energy-efficient industrial electrochemical processes; (4) molten carbonate fuel cells for use by electric utilities; (5) coal technology, mainly fluidized-bed combustion of coal in the presence of SO 2 sorbent of limestone; (6) heat- and seed-recovery technology for open-cycle magnetohydrodynamic systems; (7) solar energy collectors and thermal energy storage; (8) fast breeder reactor chemistry research - chemical support of reactor safety studies, chemistry of irradiated fuels, and sodium technology; (9) fuel cycle technology - management of nuclear wastes, reprocessing of nuclear fuels, and proof-of-breeding studies for the Light Water Breeder Reactor; and (10) magnetic fusion research - systems analysis and engineering experimentation, materials research, and neutron dosimetry and damage analysis. The CEN Division also has a basic energy sciences program, which includes experimental and theoretical research on (1) the catalytic hydrogenation of carbon monoxide and methanol homologation, (2) the thermodynamic properties of a wide variety of inorganic and organic materials, (3) significant mechanisms for the formation of atmospheric sulfate and nitrogen-bearing aerosols, (4) processes occurring at electrodes and in electrolytes, and (5) the physical properties of salt vapors. In addition, the Division operated the Central Analytical Chemistry Laboratory

  12. Chemical Technology Division annual technical report 1989

    International Nuclear Information System (INIS)

    1990-03-01

    Highlights of the Chemical Technology (CMT) Division's activities during 1989 are presented. In this period, CMT conducted research and development in the following areas: (1) electrochemical technology, including high-performance batteries (mainly lithium/iron sulfide and sodium/metal chloride), aqueous batteries (lead-acid and nickel/iron), and advanced fuel cells with molten carbonate and solid oxide electrolytes: (2) coal utilization, including the heat and seed recovery technology for coal-fired magnetohydrodynamics plants and the technology for fluidized-bed combustion; (3) methods for recovery of energy from municipal waste and techniques for treatment of hazardous organic waste; (4) nuclear technology related to a process for separating and recovering transuranic elements from nuclear waste and for producing 99 Mo from low-enriched uranium targets, the recovery processes for discharged fuel and the uranium blanket in a sodium-cooled fast reactor (the Integral Fast Reactor), and waste management; and (5) physical chemistry of selected materials in environments simulating those of fission and fusion energy systems. The Division also has a program in basic chemistry research in the areas of fluid catalysis for converting small molecules to desired products; materials chemistry for superconducting oxides and associated and ordered solutions at high temperatures; interfacial processes of importance to corrosion science, high-temperature superconductivity, and catalysis; and the geochemical processes responsible for trace-element migration within the earth's crust. The Division continued to be administratively responsible for and the major user of the Analytical Chemistry Laboratory at Argonne National Laboratory (ANL)

  13. Chemical Technology Division annual technical report, 1988

    International Nuclear Information System (INIS)

    1989-05-01

    Highlights of the Chemical Technology (CMT) Divisions's activities during 1988 are presented. In this period, CMT conducted research and development in the following areas: (1) high-performance batteries (mainly lithium-alloy/metal sulfide, sodium/metal chloride, and sodium/sulfur); (2) aqueous batteries (lead-acid, nickel/iron, etc.); (3) advanced fuel cells with molten carbonate or solid oxide electrolytes; (4) coal utilization, including the heat and seed recovery technology for coal-fired magnetohydrodynamics plants and the technology for fluidized-bed combustion; (5) methods for recovery of energy from municipal waste and techniques for treatment of hazardous chemical water; (6) nuclear technology related to a process for separating and recovering transuranic elements from nuclear waste and for producing /sup 99/Mo from low-enriched uranium targets, the recovery processes for discharged fuel and the uranium blanket in a sodium-cooled fast reactor, and waste management; and (7) physical chemistry of selected materials in environments simulating those of fission and fusion energy systems. The Division also has a program in basic chemistry research in the areas of fluid catalysis for converting small molecules to desired products; materials chemistry for superconducting oxides and associated and ordered solutions at high temperatures; interfacial processes of importance to corrosion science, high-temperature superconductivity, and catalysis; and the geochemical processes responsible for trace-element migration within the earth's crust. The Division continued to be the major user of the technical support provided by the Analytical Chemistry Laboratory at ANL. 53 figs., 16 tabs

  14. Variety in intracellular diffusion during the cell cycle

    DEFF Research Database (Denmark)

    Selhuber-Unkel, C.; Yde, P.; Berg-Sørensen, Kirstine

    2009-01-01

    During the cell cycle, the organization of the cytoskeletal network undergoes dramatic changes. In order to reveal possible changes of the viscoelastic properties in the intracellular space during the cell cycle we investigated the diffusion of endogenous lipid granules within the fission yeast...... Schizosaccharomyces Pombe using optical tweezers. The cell cycle was divided into interphase and mitotic cell division, and the mitotic cell division was further subdivided in its stages. During all stages of the cell cycle, the granules predominantly underwent subdiffusive motion, characterized by an exponent...... a that is also linked to the viscoelastic moduli of the cytoplasm. The exponent a was significantly smaller during interphase than during any stage of the mitotic cell division, signifying that the cytoplasm was more elastic during interphase than during division. We found no significant differences...

  15. 49 CFR 1242.03 - Made by accounting divisions.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 9 2010-10-01 2010-10-01 false Made by accounting divisions. 1242.03 Section 1242... accounting divisions. The separation shall be made by accounting divisions, where such divisions are maintained, and the aggregate of the accounting divisions reported for the quarter and for the year. ...

  16. Effect of low-dose-rate irradiation on the division potential of cells in vitro. V. Human skin fibroblasts from donors with a high risk of cancer

    International Nuclear Information System (INIS)

    Diatloff, C.; Macieira-Coelho, A.

    1979-01-01

    Skin fibroblasts from normal donors, donors with ataxia-telanglectasia or Fanconi's anemia, and from 1 cancer patient were treated with repeated γ radiation at about 16 rads per hour. The remaining division potential of all fibroblasts, except for the Fanconi's anemia cells, was reduced to different extents by radiation. The growth potential of Fanconl's anemia cells was increased in all the irradiated cultures. The increase was 54% in the group that survived the longest. These results were identical to those obtained with fibroblasts from certain species that have a high probability of transformation

  17. 76 FR 31017 - Advisory Group to the Internal Revenue Service Tax Exempt and Government Entities Division (TE/GE...

    Science.gov (United States)

    2011-05-27

    ... Government Accountability Office (GAO) Report to Congressional Requesters Entitled ``Social Security... site. Indian Tribal Governments: --Supplemental Report on the Implementation of Tribal Economic Development Bonds Under the American Recovery and Reinvestment Act of 2009. --Survey of Issues Requiring...

  18. Chemical Technology Division annual technical report, 1993

    Energy Technology Data Exchange (ETDEWEB)

    Battles, J.E.; Myles, K.M.; Laidler, J.J.; Green, D.W.

    1994-04-01

    Chemical Technology (CMT) Division this period, conducted research and development in the following areas: advanced batteries and fuel cells; fluidized-bed combustion and coal-fired magnetohydrodynamics; treatment of hazardous waste and mixed hazardous/radioactive waste; reaction of nuclear waste glass and spent fuel under conditions expected for an unsaturated repository; separating and recovering transuranic elements, concentrating radioactive waste streams with advanced evaporators, and producing {sup 99}Mo from low-enriched uranium; recovering actinide from IFR core and blanket fuel in removing fission products from recycled fuel, and disposing removal of actinides in spent fuel from commercial water-cooled nuclear reactors; and physical chemistry of selected materials in environments simulating those of fission and fusion energy systems. The Division also conducts basic research in catalytic chemistry associated with molecular energy resources and novel ceramic precursors; materials chemistry of superconducting oxides, electrified metal/solution interfaces, molecular sieve structures, thin-film diamond surfaces, effluents from wood combustion, and molten silicates; and the geochemical processes involved in water-rock interactions. The Analytical Chemistry Laboratory in CMT also provides a broad range of analytical chemistry support.

  19. Chemical Technology Division annual technical report, 1993

    International Nuclear Information System (INIS)

    Battles, J.E.; Myles, K.M.; Laidler, J.J.; Green, D.W.

    1994-04-01

    Chemical Technology (CMT) Division this period, conducted research and development in the following areas: advanced batteries and fuel cells; fluidized-bed combustion and coal-fired magnetohydrodynamics; treatment of hazardous waste and mixed hazardous/radioactive waste; reaction of nuclear waste glass and spent fuel under conditions expected for an unsaturated repository; separating and recovering transuranic elements, concentrating radioactive waste streams with advanced evaporators, and producing 99 Mo from low-enriched uranium; recovering actinide from IFR core and blanket fuel in removing fission products from recycled fuel, and disposing removal of actinides in spent fuel from commercial water-cooled nuclear reactors; and physical chemistry of selected materials in environments simulating those of fission and fusion energy systems. The Division also conducts basic research in catalytic chemistry associated with molecular energy resources and novel ceramic precursors; materials chemistry of superconducting oxides, electrified metal/solution interfaces, molecular sieve structures, thin-film diamond surfaces, effluents from wood combustion, and molten silicates; and the geochemical processes involved in water-rock interactions. The Analytical Chemistry Laboratory in CMT also provides a broad range of analytical chemistry support

  20. 2017 T Division Lightning Talks

    Energy Technology Data Exchange (ETDEWEB)

    Ramsey, Marilyn Leann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Abeywardhana, Jayalath AMM [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Adams, Colin Mackenzie [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Adams, Luke Clyde [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Carter, Austin Lewis [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Ducru, Pablo Philippe [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Duignan, Thomas John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Gifford, Brendan Joel [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hills, Benjamin Hale [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hoffman, Kentaro Jack [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Khair, Adnan Ibne [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kochanski, Kelly Anne Pribble [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Ledwith, Patrick John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Leveillee, Joshua Anthony [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lewis, Sina Genevieve [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Ma, Xiaoyu [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Merians, Hugh Drake [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Moore, Bryan Alexander [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Nijjar, Parmeet Kaur [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Oles, Vladyslav [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Olszewski, Maciej W. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Philipbar, Brad Montgomery [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Reisner, Andrew Ray [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Roberts, David Benjamin [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Rufa, Dominic Antonio [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Sifain, Andrew E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Smith, Justin Steven [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Smith, Lauren Taylor Wisbey [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Svolos, Lampros [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Thibault, Joshua Ryan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Ushijima-Mwesigwa, Hayato Montezuma [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Weaver, Claire Marie [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Witzen, Wyatt Andrew [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Zentgraf, Sabine Silvia [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Alred, John Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-10-06

    All members of the T Division Community, students, staff members, group leaders, division management, and other interested individuals are invited to come and support the following student(s) as they present their Lightning Talks.

  1. Division: The Sleeping Dragon

    Science.gov (United States)

    Watson, Anne

    2012-01-01

    Of the four mathematical operators, division seems to not sit easily for many learners. Division is often described as "the odd one out". Pupils develop coping strategies that enable them to "get away with it". So, problems, misunderstandings, and misconceptions go unresolved perhaps for a lifetime. Why is this? Is it a case of "out of sight out…

  2. E-Division activities report

    International Nuclear Information System (INIS)

    Barschall, H.H.

    1979-07-01

    This report describes some of the activities in E (Experimental Physics) Division during the past year. E-Division carries out research and development in areas related to the missions of the Laboratory. Many of the activities are in pure and applied atomic and nuclear physics. In addition, this report describes work on accelerators, radiation damage, microwaves, and plasma diagnostics

  3. Podcast: The Electronic Crimes Division

    Science.gov (United States)

    Sept 26, 2016. Chris Lukas, the Special Agent in Charge of the Electronic Crimes Division within the OIG's Office of Investigations talks about computer forensics, cybercrime in the EPA and his division's role in criminal investigations.

  4. Mammalian neurogenesis requires Treacle-Plk1 for precise control of spindle orientation, mitotic progression, and maintenance of neural progenitor cells.

    Directory of Open Access Journals (Sweden)

    Daisuke Sakai

    Full Text Available The cerebral cortex is a specialized region of the brain that processes cognitive, motor, somatosensory, auditory, and visual functions. Its characteristic architecture and size is dependent upon the number of neurons generated during embryogenesis and has been postulated to be governed by symmetric versus asymmetric cell divisions, which mediate the balance between progenitor cell maintenance and neuron differentiation, respectively. The mechanistic importance of spindle orientation remains controversial, hence there is considerable interest in understanding how neural progenitor cell mitosis is controlled during neurogenesis. We discovered that Treacle, which is encoded by the Tcof1 gene, is a novel centrosome- and kinetochore-associated protein that is critical for spindle fidelity and mitotic progression. Tcof1/Treacle loss-of-function disrupts spindle orientation and cell cycle progression, which perturbs the maintenance, proliferation, and localization of neural progenitors during cortical neurogenesis. Consistent with this, Tcof1(+/- mice exhibit reduced brain size as a consequence of defects in neural progenitor maintenance. We determined that Treacle elicits its effect via a direct interaction with Polo-like kinase1 (Plk1, and furthermore we discovered novel in vivo roles for Plk1 in governing mitotic progression and spindle orientation in the developing mammalian cortex. Increased asymmetric cell division, however, did not promote increased neuronal differentiation. Collectively our research has therefore identified Treacle and Plk1 as novel in vivo regulators of spindle fidelity, mitotic progression, and proliferation in the maintenance and localization of neural progenitor cells. Together, Treacle and Plk1 are critically required for proper cortical neurogenesis, which has important implications in the regulation of mammalian brain size and the pathogenesis of congenital neurodevelopmental disorders such as microcephaly.

  5. Division of Integrity and Materials

    International Nuclear Information System (INIS)

    Zdarek, J.

    1995-01-01

    The organization structure is described of the Division of Integrity and Materials, Institute of Nuclear Research plc, Rez, and the main fields of their activities given. Listed are the major research projects of the Division in 1994. (Z.S.)

  6. 2016 T Division Lightning Talks

    Energy Technology Data Exchange (ETDEWEB)

    Ramsey, Marilyn Leann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Adams, Luke Clyde [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Ferre, Gregoire Robing [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Grantcharov, Vesselin [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Iaroshenko, Oleksandr [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Krishnapriyan, Aditi [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Kurtakoti, Prajvala Kishore [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Le Thien, Minh Quan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Lim, Jonathan Ng [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Low, Thaddeus Song En [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Lystrom, Levi Aaron [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Ma, Xiaoyu [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Nguyen, Hong T. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Pogue, Sabine Silvia [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Orandle, Zoe Ann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Reisner, Andrew Ray [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Revard, Benjamin Charles [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Roy, Julien [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Sandor, Csanad [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Slavkova, Kalina Polet [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Weichman, Kathleen Joy [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Wu, Fei [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Yang, Yang [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division

    2016-11-29

    These are the slides for all of the 2016 T Division lightning talks. There are 350 pages worth of slides from different presentations, all of which cover different topics within the theoretical division at Los Alamos National Laboratory (LANL).

  7. Analytical Chemistry Division's sample transaction system

    International Nuclear Information System (INIS)

    Stanton, J.S.; Tilson, P.A.

    1980-10-01

    The Analytical Chemistry Division uses the DECsystem-10 computer for a wide range of tasks: sample management, timekeeping, quality assurance, and data calculation. This document describes the features and operating characteristics of many of the computer programs used by the Division. The descriptions are divided into chapters which cover all of the information about one aspect of the Analytical Chemistry Division's computer processing

  8. Asymmetric cell division and Notch signaling specify dopaminergic neurons in Drosophila.

    Directory of Open Access Journals (Sweden)

    Murni Tio

    Full Text Available In Drosophila, dopaminergic (DA neurons can be found from mid embryonic stages of development till adulthood. Despite their functional involvement in learning and memory, not much is known about the developmental as well as molecular mechanisms involved in the events of DA neuronal specification, differentiation and maturation. In this report we demonstrate that most larval DA neurons are generated during embryonic development. Furthermore, we show that loss of function (l-o-f mutations of genes of the apical complex proteins in the asymmetric cell division (ACD machinery, such as inscuteable and bazooka result in supernumerary DA neurons, whereas l-o-f mutations of genes of the basal complex proteins such as numb result in loss or reduction of DA neurons. In addition, when Notch signaling is reduced or abolished, additional DA neurons are formed and conversely, when Notch signaling is activated, less DA neurons are generated. Our data demonstrate that both ACD and Notch signaling are crucial mechanisms for DA neuronal specification. We propose a model in which ACD results in differential Notch activation in direct siblings and in this context Notch acts as a repressor for DA neuronal specification in the sibling that receives active Notch signaling. Our study provides the first link of ACD and Notch signaling in the specification of a neurotransmitter phenotype in Drosophila. Given the high degree of conservation between Drosophila and vertebrate systems, this study could be of significance to mechanisms of DA neuronal differentiation not limited to flies.

  9. Optical Code-Division Multiple-Access and Wavelength Division Multiplexing: Hybrid Scheme Review

    OpenAIRE

    P. Susthitha Menon; Sahbudin Shaari; Isaac A.M. Ashour; Hesham A. Bakarman

    2012-01-01

    Problem statement: Hybrid Optical Code-Division Multiple-Access (OCDMA) and Wavelength-Division Multiplexing (WDM) have flourished as successful schemes for expanding the transmission capacity as well as enhancing the security for OCDMA. However, a comprehensive review related to this hybrid system are lacking currently. Approach: The purpose of this paper is to review the literature on OCDMA-WDM overlay systems, including our hybrid approach of one-dimensional coding of SAC OCDMA with WDM si...

  10. Chemical Technology Division annual technical report 1997

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-06-01

    The Chemical Technology (CMT) Division is a diverse technical organization with principal emphases in environmental management and development of advanced energy sources. The Division conducts research and development in three general areas: (1) development of advanced power sources for stationary and transportation applications and for consumer electronics, (2) management of high-level and low-level nuclear wastes and hazardous wastes, and (3) electrometallurgical treatment of spent nuclear fuel. The Division also performs basic research in catalytic chemistry involving molecular energy resources, mechanisms of ion transport in lithium battery electrolytes, and the chemistry of technology-relevant materials and electrified interfaces. In addition, the Division operates the Analytical Chemistry Laboratory, which conducts research in analytical chemistry and provides analytical services for programs at Argonne National Laboratory (ANL) and other organizations. Technical highlights of the Division`s activities during 1997 are presented.

  11. Lightning Talks 2015: Theoretical Division

    Energy Technology Data Exchange (ETDEWEB)

    Shlachter, Jack S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-11-25

    This document is a compilation of slides from a number of student presentations given to LANL Theoretical Division members. The subjects cover the range of activities of the Division, including plasma physics, environmental issues, materials research, bacterial resistance to antibiotics, and computational methods.

  12. Chemical technology division: Annual technical report 1987

    International Nuclear Information System (INIS)

    1988-05-01

    Highlights of the Chemical Technology (CMT) Division's activities during 1987 are presented. In this period, CMT conducted research and development in the following areas: (1) high-performance batteries--mainly lithium-alloy/metal sulfide and sodium/sulfur; (2) aqueous batteries (lead-acid, nickel/iron, etc.); (3) advanced fuel cells with molten carbonate or solid oxide electrolytes; (4) coal utilization, including the heat and seed recovery technology for coal-fired magnetohydrodynamics plants and the technology for fluidized-bed combustion; (5) methods for the electromagnetic continuous casting of steel sheet and for the purification of ferrous scrap; (6) methods for recovery of energy from municipal waste and techniques for treatment of hazardous organic waste; (7) nuclear technology related to a process for separating and recovering transuranic elements from nuclear waste, the recovery processes for discharged fuel and the uranium blanket in a sodium-cooled fast reactor, and waste management; and (8) physical chemistry of selected materials in environments simulating those of fission and fusion energy systems. The Division also has a program in basic chemistry research in the areas of fluid catalysis for converting small molecules to desired products; materials chemistry for liquids and vapors at high temperatures; interfacial processes of importance to corrosion science, high-temperature superconductivity, and catalysis; the thermochemistry of various minerals; and the geochemical processes responsible for trace-element migration within the earth's crust. The Division continued to be the major user of the technical support provided by the Analytical Chemistry Laboratory at ANL. 54 figs., 9 tabs

  13. Chemical Technology Division annual technical report 1989

    Energy Technology Data Exchange (ETDEWEB)

    1990-03-01

    Highlights of the Chemical Technology (CMT) Division's activities during 1989 are presented. In this period, CMT conducted research and development in the following areas: (1) electrochemical technology, including high-performance batteries (mainly lithium/iron sulfide and sodium/metal chloride), aqueous batteries (lead-acid and nickel/iron), and advanced fuel cells with molten carbonate and solid oxide electrolytes: (2) coal utilization, including the heat and seed recovery technology for coal-fired magnetohydrodynamics plants and the technology for fluidized-bed combustion; (3) methods for recovery of energy from municipal waste and techniques for treatment of hazardous organic waste; (4) nuclear technology related to a process for separating and recovering transuranic elements from nuclear waste and for producing {sup 99}Mo from low-enriched uranium targets, the recovery processes for discharged fuel and the uranium blanket in a sodium-cooled fast reactor (the Integral Fast Reactor), and waste management; and (5) physical chemistry of selected materials in environments simulating those of fission and fusion energy systems. The Division also has a program in basic chemistry research in the areas of fluid catalysis for converting small molecules to desired products; materials chemistry for superconducting oxides and associated and ordered solutions at high temperatures; interfacial processes of importance to corrosion science, high-temperature superconductivity, and catalysis; and the geochemical processes responsible for trace-element migration within the earth's crust. The Division continued to be administratively responsible for and the major user of the Analytical Chemistry Laboratory at Argonne National Laboratory (ANL).

  14. Chemical technology division: Annual technical report 1987

    Energy Technology Data Exchange (ETDEWEB)

    1988-05-01

    Highlights of the Chemical Technology (CMT) Division's activities during 1987 are presented. In this period, CMT conducted research and development in the following areas: (1) high-performance batteries--mainly lithium-alloy/metal sulfide and sodium/sulfur; (2) aqueous batteries (lead-acid, nickel/iron, etc.); (3) advanced fuel cells with molten carbonate or solid oxide electrolytes; (4) coal utilization, including the heat and seed recovery technology for coal-fired magnetohydrodynamics plants and the technology for fluidized-bed combustion; (5) methods for the electromagnetic continuous casting of steel sheet and for the purification of ferrous scrap; (6) methods for recovery of energy from municipal waste and techniques for treatment of hazardous organic waste; (7) nuclear technology related to a process for separating and recovering transuranic elements from nuclear waste, the recovery processes for discharged fuel and the uranium blanket in a sodium-cooled fast reactor, and waste management; and (8) physical chemistry of selected materials in environments simulating those of fission and fusion energy systems. The Division also has a program in basic chemistry research in the areas of fluid catalysis for converting small molecules to desired products; materials chemistry for liquids and vapors at high temperatures; interfacial processes of importance to corrosion science, high-temperature superconductivity, and catalysis; the thermochemistry of various minerals; and the geochemical processes responsible for trace-element migration within the earth's crust. The Division continued to be the major user of the technical support provided by the Analytical Chemistry Laboratory at ANL. 54 figs., 9 tabs.

  15. Chemical Technology Division annual technical report, 1986

    International Nuclear Information System (INIS)

    1987-06-01

    Highlights of the Chemical Technology (CMT) Division's activities during 1986 are presented. In this period, CMT conducted research and development in areas that include the following: (1) high-performance batteries - mainly lithium-alloy/metal sulfide and sodium/sulfur; (2) aqueous batteries (lead-acid, nickel/iron, etc.); (3) advanced fuel cells with molten carbonate or solid oxide electrolytes; (4) coal utilization, including the heat and seed recovery technology for coal-fired magnetohydrodynamics plants, the technology for fluidized-bed combustion, and a novel concept for CO 2 recovery from fossil fuel combustion; (5) methods for recovery of energy from municipal waste; (6) methods for the electromagnetic continuous casting of steel sheet; (7) techniques for treatment of hazardous waste such as reactive metals and trichloroethylenes; (8) nuclear technology related to waste management, a process for separating and recovering transuranic elements from nuclear waste, and the recovery processes for discharged fuel and the uranium blanket in a sodium-cooled fast reactor; and (9) physical chemistry of selected materials in environments simulating those of fission and fusion energy systems. The Division also has a program in basic chemistry research in the areas of catalytic hydrogenation and catalytic oxidation; materials chemistry for associated and ordered solutions at high temperatures; interfacial processes of importance to corrosion science, surface science, and catalysis; the thermochemistry of zeolites and related silicates; and the geochemical processes responsible for trace-element migration within the earth's crust. The Division continued to be the major user of the technical support provided by the Analytical Chemistry Laboratory at ANL. 127 refs., 71 figs., 8 tabs

  16. Wp³yw podatku od spadków i darowizn na kszta³towanie siê dochodów w³asnych gminy na przyk³adzie wybranych gmin/The impact of inheritance and gift tax on the formation of local government revenue with selected local governments as an example

    OpenAIRE

    Daria Królak

    2014-01-01

    The purpose of this article is to examine how strong impact on local government revenues has an inheritance and gift tax. The author presents three different classifications of local government revenues: statutory and two classifications taken from Beata Guziejewska’s and Krystyna Piotrowska-Marczak’s books. The analysis shows that the inheritance and gift tax, mentioned in the statutory division as a local government income, has a marginal impact on revenue’s formation. However, in the case ...

  17. Visualization of candidate division OP3 cocci in limonene-degrading methanogenic cultures

    DEFF Research Database (Denmark)

    Rotaru, Amelia-Elena; Schauer, Regina; Probian, Christina

    2012-01-01

    Members of candidate division OP3 were detected in 16S rRNA gene clone libraries from methanogenic enrichment cultures that utilized limonene as a carbon and energy source. We developed probes for the visualization of OP3 cells. In situ hybridization experiments with newly designed OP3-specific...

  18. Bridging the Timescales of Single-Cell and Population Dynamics

    Science.gov (United States)

    Jafarpour, Farshid; Wright, Charles S.; Gudjonson, Herman; Riebling, Jedidiah; Dawson, Emma; Lo, Klevin; Fiebig, Aretha; Crosson, Sean; Dinner, Aaron R.; Iyer-Biswas, Srividya

    2018-04-01

    How are granular details of stochastic growth and division of individual cells reflected in smooth deterministic growth of population numbers? We provide an integrated, multiscale perspective of microbial growth dynamics by formulating a data-validated theoretical framework that accounts for observables at both single-cell and population scales. We derive exact analytical complete time-dependent solutions to cell-age distributions and population growth rates as functionals of the underlying interdivision time distributions, for symmetric and asymmetric cell division. These results provide insights into the surprising implications of stochastic single-cell dynamics for population growth. Using our results for asymmetric division, we deduce the time to transition from the reproductively quiescent (swarmer) to the replication-competent (stalked) stage of the Caulobacter crescentus life cycle. Remarkably, population numbers can spontaneously oscillate with time. We elucidate the physics leading to these population oscillations. For C. crescentus cells, we show that a simple measurement of the population growth rate, for a given growth condition, is sufficient to characterize the condition-specific cellular unit of time and, thus, yields the mean (single-cell) growth and division timescales, fluctuations in cell division times, the cell-age distribution, and the quiescence timescale.

  19. A Stochastic Model of the Yeast Cell Cycle Reveals Roles for Feedback Regulation in Limiting Cellular Variability.

    Science.gov (United States)

    Barik, Debashis; Ball, David A; Peccoud, Jean; Tyson, John J

    2016-12-01

    The cell division cycle of eukaryotes is governed by a complex network of cyclin-dependent protein kinases (CDKs) and auxiliary proteins that govern CDK activities. The control system must function reliably in the context of molecular noise that is inevitable in tiny yeast cells, because mistakes in sequencing cell cycle events are detrimental or fatal to the cell or its progeny. To assess the effects of noise on cell cycle progression requires not only extensive, quantitative, experimental measurements of cellular heterogeneity but also comprehensive, accurate, mathematical models of stochastic fluctuations in the CDK control system. In this paper we provide a stochastic model of the budding yeast cell cycle that accurately accounts for the variable phenotypes of wild-type cells and more than 20 mutant yeast strains simulated in different growth conditions. We specifically tested the role of feedback regulations mediated by G1- and SG2M-phase cyclins to minimize the noise in cell cycle progression. Details of the model are informed and tested by quantitative measurements (by fluorescence in situ hybridization) of the joint distributions of mRNA populations in yeast cells. We use the model to predict the phenotypes of ~30 mutant yeast strains that have not yet been characterized experimentally.

  20. A Stochastic Model of the Yeast Cell Cycle Reveals Roles for Feedback Regulation in Limiting Cellular Variability.

    Directory of Open Access Journals (Sweden)

    Debashis Barik

    2016-12-01

    Full Text Available The cell division cycle of eukaryotes is governed by a complex network of cyclin-dependent protein kinases (CDKs and auxiliary proteins that govern CDK activities. The control system must function reliably in the context of molecular noise that is inevitable in tiny yeast cells, because mistakes in sequencing cell cycle events are detrimental or fatal to the cell or its progeny. To assess the effects of noise on cell cycle progression requires not only extensive, quantitative, experimental measurements of cellular heterogeneity but also comprehensive, accurate, mathematical models of stochastic fluctuations in the CDK control system. In this paper we provide a stochastic model of the budding yeast cell cycle that accurately accounts for the variable phenotypes of wild-type cells and more than 20 mutant yeast strains simulated in different growth conditions. We specifically tested the role of feedback regulations mediated by G1- and SG2M-phase cyclins to minimize the noise in cell cycle progression. Details of the model are informed and tested by quantitative measurements (by fluorescence in situ hybridization of the joint distributions of mRNA populations in yeast cells. We use the model to predict the phenotypes of ~30 mutant yeast strains that have not yet been characterized experimentally.

  1. Division of household tasks and financial management

    NARCIS (Netherlands)

    Antonides, G.

    2011-01-01

    Both the standard economic model and bargaining theory make predictions about financial management and the division of household labor between household partners. Using a large Internet survey, we have tested several predictions about task divisions reported by Dutch household partners. The division

  2. Real-time tracking of cell cycle progression during CD8+ effector and memory T-cell differentiation.

    Science.gov (United States)

    Kinjyo, Ichiko; Qin, Jim; Tan, Sioh-Yang; Wellard, Cameron J; Mrass, Paulus; Ritchie, William; Doi, Atsushi; Cavanagh, Lois L; Tomura, Michio; Sakaue-Sawano, Asako; Kanagawa, Osami; Miyawaki, Atsushi; Hodgkin, Philip D; Weninger, Wolfgang

    2015-02-24

    The precise pathways of memory T-cell differentiation are incompletely understood. Here we exploit transgenic mice expressing fluorescent cell cycle indicators to longitudinally track the division dynamics of individual CD8(+) T cells. During influenza virus infection in vivo, naive T cells enter a CD62L(intermediate) state of fast proliferation, which continues for at least nine generations. At the peak of the anti-viral immune response, a subpopulation of these cells markedly reduces their cycling speed and acquires a CD62L(hi) central memory cell phenotype. Construction of T-cell family division trees in vitro reveals two patterns of proliferation dynamics. While cells initially divide rapidly with moderate stochastic variations of cycling times after each generation, a slow-cycling subpopulation displaying a CD62L(hi) memory phenotype appears after eight divisions. Phenotype and cell cycle duration are inherited by the progeny of slow cyclers. We propose that memory precursors cell-intrinsically modulate their proliferative activity to diversify differentiation pathways.

  3. Energy and Environmental Systems Division 1981 research review

    International Nuclear Information System (INIS)

    1982-04-01

    To effectively manage the nation's energy and natural resources, government and industry leaders need accurate information regarding the performance and economics of advanced energy systems and the costs and benefits of public-sector initiatives. The Energy and Environmental Systems Division (EES) of Argonne National Laboratory conducts applied research and development programs that provide such information through systems analysis, geophysical field research, and engineering studies. During 1981, the division: analyzed the production economics of specific energy resources, such as biomass and tight sands gas; developed and transferred to industry economically efficient techniques for addressing energy-related resource management and environmental protection problems, such as the reclamation of strip-mined land; determined the engineering performance and cost of advanced energy-supply and pollution-control systems; analyzed future markets for district heating systems and other emerging energy technologies; determined, in strategic planning studies, the availability of resources needed for new energy technologies, such as the imported metals used in advanced electric-vehicle batteries; evaluated the effectiveness of strategies for reducing scarce-fuel consumption in the transportation sector; identified the costs and benefits of measures designed to stabilize the financial condition of US electric utilities; estimated the costs of nuclear reactor shutdowns and evaluated geologic conditions at potential sites for permanent underground storage of nuclear waste; evaluated the cost-effectiveness of environmental regulations, particularly those affecting coal combustion; and identified the environmental effects of energy technologies and transportation systems

  4. E-Division activities report

    International Nuclear Information System (INIS)

    Barschall, H.H.

    1981-07-01

    This report describes some of the activities in E (Experimental Physics) Division during the past year. E-Division carries out research and development in areas related to the missions of the Laboratory. Many of the activities are in pure and applied atomic and nuclear physics and in material science. In addition this report describes work on accelerators, microwaves, plasma diagnostics, determination of atmospheric oxygen and of nitrogen in tissue

  5. Chemical Sciences Division: Annual report 1992

    International Nuclear Information System (INIS)

    1993-10-01

    The Chemical Sciences Division (CSD) is one of twelve research Divisions of the Lawrence Berkeley Laboratory, a Department of Energy National Laboratory. The CSD is composed of individual groups and research programs that are organized into five scientific areas: Chemical Physics, Inorganic/Organometallic Chemistry, Actinide Chemistry, Atomic Physics, and Physical Chemistry. This report describes progress by the CSD for 1992. Also included are remarks by the Division Director, a description of work for others (United States Office of Naval Research), and appendices of the Division personnel and an index of investigators. Research reports are grouped as Fundamental Interactions (Photochemical and Radiation Sciences, Chemical Physics, Atomic Physics) or Processes and Techniques (Chemical Energy, Heavy-Element Chemistry, and Chemical Engineering Sciences)

  6. Regional control of Drosophila gut stem cell proliferation: EGF establishes GSSC proliferative set point & controls emergence from quiescence.

    Science.gov (United States)

    Strand, Marie; Micchelli, Craig A

    2013-01-01

    Adult stem cells vary widely in their rates of proliferation. Some stem cells are constitutively active, while others divide only in response to injury. The mechanism controlling this differential proliferative set point is not well understood. The anterior-posterior (A/P) axis of the adult Drosophila midgut has a segmental organization, displaying physiological compartmentalization and region-specific epithelia. These distinct midgut regions are maintained by defined stem cell populations with unique division schedules, providing an excellent experimental model with which to investigate this question. Here, we focus on the quiescent gastric stem cells (GSSCs) of the acidic copper cell region (CCR), which exhibit the greatest period of latency between divisions of all characterized gut stem cells, to define the molecular basis of differential stem cell activity. Our molecular genetic analysis demonstrates that the mitogenic EGF signaling pathway is a limiting factor controlling GSSC proliferation. We find that under baseline conditions, when GSSCs are largely quiescent, the lowest levels of EGF ligands in the midgut are found in the CCR. However, acute epithelial injury by enteric pathogens leads to an increase in EGF ligand expression in the CCR and rapid expansion of the GSSC lineage. Thus, the unique proliferative set points for gut stem cells residing in physiologically distinct compartments are governed by regional control of niche signals along the A/P axis.

  7. Regional control of Drosophila gut stem cell proliferation: EGF establishes GSSC proliferative set point & controls emergence from quiescence.

    Directory of Open Access Journals (Sweden)

    Marie Strand

    Full Text Available Adult stem cells vary widely in their rates of proliferation. Some stem cells are constitutively active, while others divide only in response to injury. The mechanism controlling this differential proliferative set point is not well understood. The anterior-posterior (A/P axis of the adult Drosophila midgut has a segmental organization, displaying physiological compartmentalization and region-specific epithelia. These distinct midgut regions are maintained by defined stem cell populations with unique division schedules, providing an excellent experimental model with which to investigate this question. Here, we focus on the quiescent gastric stem cells (GSSCs of the acidic copper cell region (CCR, which exhibit the greatest period of latency between divisions of all characterized gut stem cells, to define the molecular basis of differential stem cell activity. Our molecular genetic analysis demonstrates that the mitogenic EGF signaling pathway is a limiting factor controlling GSSC proliferation. We find that under baseline conditions, when GSSCs are largely quiescent, the lowest levels of EGF ligands in the midgut are found in the CCR. However, acute epithelial injury by enteric pathogens leads to an increase in EGF ligand expression in the CCR and rapid expansion of the GSSC lineage. Thus, the unique proliferative set points for gut stem cells residing in physiologically distinct compartments are governed by regional control of niche signals along the A/P axis.

  8. Comparative proteome analysis between C . briggsae embryos and larvae reveals a role of chromatin modification proteins in embryonic cell division

    KAUST Repository

    An, Xiaomeng

    2017-06-21

    Caenorhabditis briggsae has emerged as a model for comparative biology against model organism C. elegans. Most of its cell fate specifications are completed during embryogenesis whereas its cell growth is achieved mainly in larval stages. The molecular mechanism underlying the drastic developmental changes is poorly understood. To gain insights into the molecular changes between the two stages, we compared the proteomes between the two stages using iTRAQ. We identified a total of 2,791 proteins in the C. briggsae embryos and larvae, 247 of which undergo up- or down-regulation between the two stages. The proteins that are upregulated in the larval stages are enriched in the Gene Ontology categories of energy production, protein translation, and cytoskeleton; whereas those upregulated in the embryonic stage are enriched in the categories of chromatin dynamics and posttranslational modification, suggesting a more active chromatin modification in the embryos than in the larva. Perturbation of a subset of chromatin modifiers followed by cell lineage analysis suggests their roles in controlling cell division pace. Taken together, we demonstrate a general molecular switch from chromatin modification to metabolism during the transition from C. briggsae embryonic to its larval stages using iTRAQ approach. The switch might be conserved across metazoans.

  9. Details Matter: Noise and Model Structure Set the Relationship between Cell Size and Cell Cycle Timing

    Directory of Open Access Journals (Sweden)

    Felix Barber

    2017-11-01

    Full Text Available Organisms across all domains of life regulate the size of their cells. However, the means by which this is done is poorly understood. We study two abstracted “molecular” models for size regulation: inhibitor dilution and initiator accumulation. We apply the models to two settings: bacteria like Escherichia coli, that grow fully before they set a division plane and divide into two equally sized cells, and cells that form a bud early in the cell division cycle, confine new growth to that bud, and divide at the connection between that bud and the mother cell, like the budding yeast Saccharomyces cerevisiae. In budding cells, delaying cell division until buds reach the same size as their mother leads to very weak size control, with average cell size and standard deviation of cell size increasing over time and saturating up to 100-fold higher than those values for cells that divide when the bud is still substantially smaller than its mother. In budding yeast, both inhibitor dilution or initiator accumulation models are consistent with the observation that the daughters of diploid cells add a constant volume before they divide. This “adder” behavior has also been observed in bacteria. We find that in bacteria an inhibitor dilution model produces adder correlations that are not robust to noise in the timing of DNA replication initiation or in the timing from initiation of DNA replication to cell division (the C+D period. In contrast, in bacteria an initiator accumulation model yields robust adder correlations in the regime where noise in the timing of DNA replication initiation is much greater than noise in the C + D period, as reported previously (Ho and Amir, 2015. In bacteria, division into two equally sized cells does not broaden the size distribution.

  10. Energy Technology Division research summary 2001

    International Nuclear Information System (INIS)

    2001-01-01

    The Energy Technology Division provides materials and engineering technology support to a wide range of programs important to the U.S. Department of Energy. As shown on the preceding page, the Division is organized into eight sections, four with concentrations in the materials area and four in engineering technology. Materials expertise includes fabrication, mechanical properties, corrosion, friction and lubrication, and irradiation effects. Our major engineering strengths are in heat and mass flow, sensors and instrumentation, nondestructive testing, transportation, and electromechanics and superconductivity applications. The Division Safety Coordinator, Environmental Compliance Officer, Quality Assurance Representative, Financial Administrator, and Communication Coordinator report directly to the Division Director. The Division Director is personally responsible for cultural diversity and is a member of the Laboratory-wide Cultural Diversity Advisory Committee. This Overview highlights some major ET research areas. Research related to the operational safety of commercial light water nuclear reactors (LWRs) for the U.S. Nuclear Regulatory Commission (NRC) remains a significant area of interest for the Division. We currently have programs on environmentally assisted cracking, steam generator integrity, and the integrity of high-burnup fuel during loss-of-coolant accidents. The bulk of the NRC research work is carried out by three ET sections: Corrosion and Mechanics of Materials; Irradiation Performance; and Sensors, Instrumentation, and Nondestructive Evaluation

  11. The 1988 Leti Division progress report

    International Nuclear Information System (INIS)

    Anon.

    1988-01-01

    The 1988 progress report of the CEA's LETI Division (Division of Electronics, Technology and Instrumentation, France) is presented. The missions of LETI Division involve military and nuclear applications of electronics and fundamental research. The research programs developed in 1988 are the following: materials and components, non-volatile silicon memories, silicon-over-insulator, integrated circuits technologies, common experimental laboratory (opened to the European community), mass memories, photodetectors, micron sensors and flat screens [fr

  12. A generalised age- and phase-structured model of human tumour cell populations both unperturbed and exposed to a range of cancer therapies.

    Science.gov (United States)

    Basse, Britta; Ubezio, Paolo

    2007-07-01

    We develop a general mathematical model for a population of cells differentiated by their position within the cell division cycle. A system of partial differential equations governs the kinetics of cell densities in certain phases of the cell division cycle dependent on time t (hours) and an age-like variable tau (hours) describing the time since arrival in a particular phase of the cell division cycle. Transition rate functions control the transfer of cells between phases. We first obtain a theoretical solution on the infinite domain -infinity infinity. We then assume that age distributions at time t=0 are known and write our solution in terms of these age distributions on t=0. In practice, of course, these age distributions are unknown. All is not lost, however, because a cell line before treatment usually lies in a state of asynchronous balanced growth where the proportion of cells in each phase of the cell cycle remain constant. We assume that an unperturbed cell line has four distinct phases and that the rate of transition between phases is constant within a short period of observation ('short' relative to the whole history of the tumour growth) and we show that under certain conditions, this is equivalent to exponential growth or decline. We can then gain expressions for the age distributions. So, in short, our approach is to assume that we have an unperturbed cell line on t cell line is exposed to cancer therapy. This corresponds to a change in the transition rate functions and perhaps incorporation of additional phases of the cell cycle. We discuss a number of these cancer therapies and applications of the model.

  13. Energy Technology Division research summary - 1999.

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-03-31

    The Energy Technology Division provides materials and engineering technology support to a wide range of programs important to the US Department of Energy. As shown on the preceding page, the Division is organized into ten sections, five with concentrations in the materials area and five in engineering technology. Materials expertise includes fabrication, mechanical properties, corrosion, friction and lubrication, and irradiation effects. Our major engineering strengths are in heat and mass flow, sensors and instrumentation, nondestructive testing, transportation, and electromechanics and superconductivity applications. The Division Safety Coordinator, Environmental Compliance Officers, Quality Assurance Representative, Financial Administrator, and Communication Coordinator report directly to the Division Director. The Division Director is personally responsible for cultural diversity and is a member of the Laboratory-wide Cultural Diversity Advisory Committee. The Division's capabilities are generally applied to issues associated with energy production, transportation, utilization, or conservation, or with environmental issues linked to energy. As shown in the organization chart on the next page, the Division reports administratively to the Associate Laboratory Director (ALD) for Energy and Environmental Science and Technology (EEST) through the General Manager for Environmental and Industrial Technologies. While most of our programs are under the purview of the EEST ALD, we also have had programs funded under every one of the ALDs. Some of our research in superconductivity is funded through the Physical Research Program ALD. We also continue to work on a number of nuclear-energy-related programs under the ALD for Engineering Research. Detailed descriptions of our programs on a section-by-section basis are provided in the remainder of this book.

  14. Cell division factors from crown gall tumors: a strategy for structural elucidation

    International Nuclear Information System (INIS)

    Manning, K.S.

    1985-01-01

    Mitogenic compounds present in extracts of Vinca rosea crown gall tumor tissue were investigated. An isolation procedure, consisting of solvent partitions and reverse phase chromatography, has yielded a group of isomeric compounds which show activity in the tobacco pith bioassay. Initial characterizations revealed an unsaturated base, a sugar residue, a β-linked glucose, an allylic alcohol, and two methyl groups. A two part strategy of mass spectrometry (MS) in combination with proton nuclear magnetic resonance ( 1 H NMR) was envisioned. The aglycone structure would be determined by MS and the regiochemical relationships among the structural units would be defined by 1 H NMR data. The utility of this approach was demonstrated by the structure assignment of a specific inhibitor of β-D-glucuronidase, 2(S)-carboxy-3(R),4(R),5(S)-trihydroxypiperidine. The relative stereochemistry of the hydroxyls was revealed by 1 H NMR and the absolute configuration was deduced by a comparison of Cotton effects with a model compound. The use of 1 H NMR to establish regiochemical relationships was investigated. Terpenes containing quaternary carbons and methyl groups were excellent models for the regiochemical problems presented by the mitogenic factors. This 1 H NMR spectroscopy has been applied to the cell division factor structure problem. These data, with information from two dimensional nOe experiments, have defined some of the regio-relationships among the structural units present in the isolated factors

  15. Physics division annual report 2006.

    Energy Technology Data Exchange (ETDEWEB)

    Glover, J.; Physics

    2008-02-28

    This report highlights the activities of the Physics Division of Argonne National Laboratory in 2006. The Division's programs include the operation as a national user facility of ATLAS, the Argonne Tandem Linear Accelerator System, research in nuclear structure and reactions, nuclear astrophysics, nuclear theory, investigations in medium-energy nuclear physics as well as research and development in accelerator technology. The mission of nuclear physics is to understand the origin, evolution and structure of baryonic matter in the universe--the core of matter, the fuel of stars, and the basic constituent of life itself. The Division's research focuses on innovative new ways to address this mission.

  16. Division of Analytical Chemistry, 1998

    DEFF Research Database (Denmark)

    Hansen, Elo Harald

    1999-01-01

    The article recounts the 1998 activities of the Division of Analytical Chemistry (DAC- formerly the Working Party on Analytical Chemistry, WPAC), which body is a division of the Federation of European Chemical Societies (FECS). Elo Harald Hansen is the Danish delegate, representing The Danish...... Chemical Society/The Society for Analytical Chemistry....

  17. Current programmes of Metallurgy Division (1991)

    International Nuclear Information System (INIS)

    1991-01-01

    Current research and development programmes of the Metallurgy Division are listed under the headings: 1)Thrust Areas, 2)High Temperature Materials Section, 3)Chemical Metallurgy Section, 4)Metallurgical Thermochemistry Section, 5)Physical Metallurgy Section, 6)Mechanical Metallurgy Section, 7)Corrosion Metallurgy Section, 8)Electrochemical Science and Technology Section, 9)Ceramics Section, and 10)Fabrication and Maintenance Group. A list of equipment in the Division and a list of sciientific personnel of the Division are also given. (M.G.B.)

  18. Cell division and endoreduplication play important roles in stem swelling of tuber mustard (Brassica juncea Coss. var. tumida Tsen et Lee).

    Science.gov (United States)

    Shi, H; Wang, L L; Sun, L T; Dong, L L; Liu, B; Chen, L P

    2012-11-01

    We investigated spatio-temporal variations in cell division and the occurrence of endoreduplication in cells of tuber mustard stems during development. Cells in the stem had 8C nuclei (C represents DNA content of a two haploid genome), since it is an allotetraploid species derived from diploid Brassica rapa (AA) and B. nigra (BB), thus indicating the occurrence of endoreduplication. Additionally, we observed a dynamic change of cell ploidy in different regions of the swollen stems, with a decrease in 4C proportion in P4-1 and a sharp increase in 8C cells that became the dominant cell type (86.33% at most) in the inner pith cells. Furthermore, cDNAs of 14 cell cycle genes and four cell expansion genes were cloned and their spatial transcripts analysed in order to understand their roles in stem development. The expression of most cell cycle genes peaked in regions of the outer pith (P2 or P3), some genes regulating S/G2 and G2/M (BjCDKB1;2, BjCYCB1;1 and BjCYCB1;2) significantly decrease in P5 and P6, while G1/S regulators (BjE2Fa, BjE2Fb and BjE2Fc) showed a relative high expression level in the inner pith (P5) where cells were undergoing endoreduplication. Coincidentally, BjXTH1and BjXTH2 were exclusively expressed in the endoreduplicated cells. Our results suggest that cells of outer pith regions (P2 and P3) mainly divide for cell proliferation, while cells of the inner pith expand through endoreduplication. Endoreduplication could trigger expression of BjXTH1 and BjXTH2 and thus function in cell expansion of the pith tissue. © 2012 German Botanical Society and The Royal Botanical Society of the Netherlands.

  19. Structure and function of stem cell pools in mammalian cell renewal systems

    International Nuclear Information System (INIS)

    Fliedner, T.M.; Nothdurft, W.

    1979-01-01

    Stem cells play a key-role in the maintenance of the equilibrium between cell loss and cell production in cell renewal systems as well as in the understanding of the radiation pathophysiology of mammalian organisms. The integrity of mammalian organisms with the need to maintain a constant ''millieu interior'' is depending on the normal functioning of cell renewal systems, especially those of epithelial surfaces and blood cell forming organs. All cell renewal systems of bodies have a very similar functional structure consisting of functional, proliferative - amplifying and stem cell compartments. They differ in transit and cell cycle times and in the number of amplification division - aside from the difference in their functional and biochemical make-up. The stem cell pools are providing the cells capable of differentiation without depleting their own kind. This can be achieved by symmetrical or assymmetrical stem cell division. In normal steady state, 50% of the stem cell division remain in the stem cell pool, while the other 50% leave it to differentiate, proliferate and mature, hemopoietic system is distributed throughout bodies. This is an important factor in the radiation biology of mammalian organisms since the loss of function in one area can be compensated for by more production in other areas, and locally depleted sites can be reseeded with the stem cells migrating in from blood. (Yamashita, S.)

  20. STUDIES ON THE MATURATION OF MYELOBLASTS INTO MYELOCYTES AND ON AMITOTIC CELL DIVISION IN THE PERIPHERAL BLOOD IN SUBACUTE MYELOBLASTIC LEUCEMIA.

    Science.gov (United States)

    Sabin, F R; Austrian, C R; Cunningham, R S; Doan, C A

    1924-11-30

    1. Myeloblasts can be discriminated in the supravital technique by the great numbers of tiny mitochondria in the cytoplasm and the absence of any other vitally stainable substance. 2. There are three stages in the maturation of myelocytes. 3. These three phases can be correlated with three types of the oxidase reaction. 4. One case of myeloblastic leucemia showed such an amount of an abnormal type of amitosis as to suggest the disordered cell division of neoplasms. 5. In this case transfusions were correlated with a maturation of myeloblasts into myelocytes, with an increase of the oxidase reaction, and with an increase in amitosis.

  1. Quality of worklife and productivity in drilling in Atomic Minerals Division

    International Nuclear Information System (INIS)

    Singh, Rajendra.

    1992-01-01

    The existing trend of drilling output in Atomic Minerals Division has been briefly discussed and human resources and its bearing on productivity in our drilling efforts emphasised. Remedial measures concerning the human resources development including creation of cells at regional and zonal levels have been suggested to give effective shape to all aspects of quality of worklife and productivity. (author)

  2. Progress report - Health Sciences Division - 1985 July 01 -December 31

    International Nuclear Information System (INIS)

    1986-02-01

    This progress report contains a topical summary of major research in the Health Sciences Division. Separate reports are included for each of the following branches: Dosimetric Research, Environmental Research, Radiation Biology, and Medical. Some of the aspects discussed include measurement and application of environmental isotopes, dosimetry and employee monitoring, environmental processes of radioisotope transport, the effects of ionizing radiation on living cells (cancer, hyperthermia, DNA, etc.), and statistics of hospital procedures

  3. Chemical and Laser Sciences Division annual report 1989

    International Nuclear Information System (INIS)

    Haines, N.

    1990-06-01

    The Chemical and Laser Sciences Division Annual Report includes articles describing representative research and development activities within the Division, as well as major programs to which the Division makes significant contributions

  4. Chemical Technology Division annual technical report, 1986

    Energy Technology Data Exchange (ETDEWEB)

    1987-06-01

    Highlights of the Chemical Technology (CMT) Division's activities during 1986 are presented. In this period, CMT conducted research and development in areas that include the following: (1) high-performance batteries - mainly lithium-alloy/metal sulfide and sodium/sulfur; (2) aqueous batteries (lead-acid, nickel/iron, etc.); (3) advanced fuel cells with molten carbonate or solid oxide electrolytes; (4) coal utilization, including the heat and seed recovery technology for coal-fired magnetohydrodynamics plants, the technology for fluidized-bed combustion, and a novel concept for CO/sub 2/ recovery from fossil fuel combustion; (5) methods for recovery of energy from municipal waste; (6) methods for the electromagnetic continuous casting of steel sheet; (7) techniques for treatment of hazardous waste such as reactive metals and trichloroethylenes; (8) nuclear technology related to waste management, a process for separating and recovering transuranic elements from nuclear waste, and the recovery processes for discharged fuel and the uranium blanket in a sodium-cooled fast reactor; and (9) physical chemistry of selected materials in environments simulating those of fission and fusion energy systems. The Division also has a program in basic chemistry research in the areas of catalytic hydrogenation and catalytic oxidation; materials chemistry for associated and ordered solutions at high temperatures; interfacial processes of importance to corrosion science, surface science, and catalysis; the thermochemistry of zeolites and related silicates; and the geochemical processes responsible for trace-element migration within the earth's crust. The Division continued to be the major user of the technical support provided by the Analytical Chemistry Laboratory at ANL. 127 refs., 71 figs., 8 tabs.

  5. Division of Information Technology - Overview

    International Nuclear Information System (INIS)

    Szlachciak, J.

    2007-01-01

    I have a great pleasure to introduce the youngest division in our Institute, namely the Division of Information Technology. The division was created in 2005, but this is the first time when it reports its activities. The main purpose of creation was a better management of al IT activities in different departments, lowering IT costs and increase security over all computer systems used be the Institute. Although we have started with small human resources, we have received a big support from other departments. Special thanks go to the Department of Detectors and Nuclear Electronics. Our division handles many service-oriented activities. In daily work we answer many IT-related questions and deliver our help in order to solve hardware and software problems. The style of our work can be described as a result-oriented one. Here is the list of our biggest achievements: · construction of the server room; · implementation of two electronic bank systems; · development of the dynamic hardware and software inventory system; · development of the Scientific Activity Database. (author)

  6. CALCULUS FROM THE PAST: MULTIPLE DELAY SYSTEMS ARISING IN CANCER CELL MODELLING

    KAUST Repository

    WAKE, G. C.; BYRNE, H. M.

    2013-01-01

    Nonlocal calculus is often overlooked in the mathematics curriculum. In this paper we present an interesting new class of nonlocal problems that arise from modelling the growth and division of cells, especially cancer cells, as they progress through the cell cycle. The cellular biomass is assumed to be unstructured in size or position, and its evolution governed by a time-dependent system of ordinary differential equations with multiple time delays. The system is linear and taken to be autonomous. As a result, it is possible to reduce its solution to that of a nonlinear matrix eigenvalue problem. This method is illustrated by considering case studies, including a model of the cell cycle developed recently by Simms, Bean and Koeber. The paper concludes by explaining how asymptotic expressions for the distribution of cells across the compartments can be determined and used to assess the impact of different chemotherapeutic agents. Copyright © 2013 Australian Mathematical Society.

  7. An examination of the stretching practices of Division I and Division III college football programs in the midwestern United States.

    Science.gov (United States)

    Judge, Lawrence W; Craig, Bruce; Baudendistal, Steve; Bodey, Kimberly J

    2009-07-01

    Research supports the use of preactivity warm-up and stretching, and the purpose of this study was to determine whether college football programs follow these guidelines. Questionnaires designed to gather demographic, professional, and educational information, as well as specific pre- and postactivity practices, were distributed via e-mail to midwestern collegiate programs from NCAA Division I and III conferences. Twenty-three male coaches (12 from Division IA schools and 11 from Division III schools) participated in the study. Division I schools employed certified strength coaches (CSCS; 100%), whereas Division III schools used mainly strength coordinators (73%), with only 25% CSCS. All programs used preactivity warm-up, with the majority employing 2-5 minutes of sport-specific jogging/running drills. Pre stretching (5-10 minutes) was performed in 19 programs (91%), with 2 (9%) performing no pre stretching. Thirteen respondents used a combination of static/proprioceptive neuromuscular facilitation/ballistic and dynamic flexibility, 5 used only dynamic flexibility, and 1 used only static stretching. All 12 Division I coaches used stretching, whereas only 9 of the 11 Division III coaches did (p = 0.22). The results indicate that younger coaches did not use pre stretching (p = 0.30). The majority of the coaches indicated that they did use post stretching, with 11 of the 12 Division I coaches using stretching, whereas only 5 of the 11 Division III coaches used stretching postactivity (p = 0.027). Divisional results show that the majority of Division I coaches use static-style stretching (p = 0.049). The results of this study indicate that divisional status, age, and certification may influence how well research guidelines are followed. Further research is needed to delineate how these factors affect coaching decisions.

  8. Algorithm development and simulation outcomes for hypoxic head and neck cancer radiotherapy using a Monte Carlo cell division model

    International Nuclear Information System (INIS)

    Harriss, W.M.; Bezak, E.; Yeoh, E.

    2010-01-01

    Full text: A temporal Monte Carlo tumour model, 'Hyp-RT'. sim ulating hypoxic head and neck cancer has been updated and extended to model radiothcrapy. The aim is to providc a convenient radiobio logical tool for clinicians to evaluate radiotherapy treatment schedules based on many individual tumour properties including oxygenation. FORTRAN95 and JA YA havc been utilised to develop the efficient algorithm, which can propagate 108 cells. Epithelial cell kill is affected by dose, oxygenation and proliferativc status. Accelerated repopulation (AR) has been modelled by increasing the symmetrical stem cell division probability, and reoxygenation (ROx) has been modelled using random incremental boosts of oxygen to the cell po ulation throughout therapy. Results The stem cell percentage and the degree of hypoxia dominate tumour growth rate. For conventional radiotherapy. 15-25% more dose was required for a hypox ic versus oxic tumours, depending on the time of AR onset (0-3 weeks after thc start of treatment). ROx of hypoxic tumours resulted in tumoUJ: sensitisation and therefore a dose reduction, of up to 35%, varying with the time of onset. Fig. I shows results for all combinations of AR and ROx onset times for the moderate hypoxia case. Conclusions In hypoxic tumours, accelerated repopulation and reoxy genation affect ccll kill in the same manner as when the effects are modelled individually. however the degree of the effect is altered and therefore the combined result is difficult to predict. providing evidence for the usefulness of computer models. Simulations have quantitatively

  9. Energy Technology Division research summary 2004

    International Nuclear Information System (INIS)

    Poeppel, R. B.; Shack, W. J.

    2004-01-01

    The Energy Technology (ET) Division provides materials and engineering technology support to a wide range of programs important to the US Department of Energy (DOE). The Division's capabilities are generally applied to technical issues associated with energy systems, biomedical engineering, transportation, and homeland security. Research related to the operational safety of commercial light water nuclear reactors (LWRs) for the US Nuclear Regulatory Commission (NRC) remains another significant area of interest for the Division. The pie chart below summarizes the ET sources of funding for FY 2004

  10. 1998 Chemical Technology Division Annual Technical Report.

    Energy Technology Data Exchange (ETDEWEB)

    Ackerman, J.P.; Einziger, R.E.; Gay, E.C.; Green, D.W.; Miller, J.F.

    1999-08-06

    The Chemical Technology (CMT) Division is a diverse technical organization with principal emphases in environmental management and development of advanced energy sources. The Division conducts research and development in three general areas: (1) development of advanced power sources for stationary and transportation applications and for consumer electronics, (2) management of high-level and low-level nuclear wastes and hazardous wastes, and (3) electrometallurgical treatment of spent nuclear fuel. The Division also performs basic research in catalytic chemistry involving molecular energy resources, mechanisms of ion transport in lithium battery electrolytes, and the chemistry of technology-relevant materials. In addition, the Division operates the Analytical Chemistry Laboratory, which conducts research in analytical chemistry and provides analytical services for programs at Argonne National Laboratory (ANL) and other organizations. Technical highlights of the Division's activities during 1998 are presented.

  11. Chemical Technology Division annual technical report 1997

    International Nuclear Information System (INIS)

    1998-06-01

    The Chemical Technology (CMT) Division is a diverse technical organization with principal emphases in environmental management and development of advanced energy sources. The Division conducts research and development in three general areas: (1) development of advanced power sources for stationary and transportation applications and for consumer electronics, (2) management of high-level and low-level nuclear wastes and hazardous wastes, and (3) electrometallurgical treatment of spent nuclear fuel. The Division also performs basic research in catalytic chemistry involving molecular energy resources, mechanisms of ion transport in lithium battery electrolytes, and the chemistry of technology-relevant materials and electrified interfaces. In addition, the Division operates the Analytical Chemistry Laboratory, which conducts research in analytical chemistry and provides analytical services for programs at Argonne National Laboratory (ANL) and other organizations. Technical highlights of the Division's activities during 1997 are presented

  12. Flagellation of Pseudomonas aeruginosa in newly divided cells

    Science.gov (United States)

    Zhao, Kun; Lee, Calvin; Anda, Jaime; Wong, Gerard

    2015-03-01

    For monotrichous bacteria, Pseudomonas aeruginosa, after cell division, one daughter cell inherits the old flagellum from its mother cell, and the other grows a new flagellum during or after cell division. It had been shown that the new flagellum grows at the distal pole of the dividing cell when the two daughter cells haven't completely separated. However, for those daughter cells who grow new flagella after division, it still remains unknown at which pole the new flagellum will grow. Here, by combining our newly developed bacteria family tree tracking techniques with genetic manipulation method, we showed that for the daughter cell who did not inherit the old flagellum, a new flagellum has about 90% chances to grow at the newly formed pole. We proposed a model for flagellation of P. aeruginosa.

  13. Cell lineages of the embryo of the nematode Caenorhabditis elegans.

    Science.gov (United States)

    Deppe, U; Schierenberg, E; Cole, T; Krieg, C; Schmitt, D; Yoder, B; von Ehrenstein, G

    1978-01-01

    Embryogenesis of the free-living soil nematode Caenorhabditis elegans produces a juvenile having about 550 cells at hatching. We have determined the lineages of 182 cells by tracing the divisions of individual cells in living embryos. An invariant pattern of cleavage divisions of the egg generates a set of stem cells. These stem cells are the founders of six stem cell lineages. Each lineage has its own clock--i.e., an autonomous rhythm of synchronous cell divisions. The rhythms are maintained in spite of extensive cellular rearrangement. The rate and the orientation of the cell divisions of the cell lineages are essentially invariant among individuals. Thus, the destiny of cells seems to depend primarily on their lineage history. The anterior position of the site of origin of the stem cells in the egg relates to the rate of the cell cycle clock, suggesting intracellular preprogramming of the uncleaved egg. We used a technique that allows normal embryogenesis, from the fertilized egg to hatching, outside the parent under a cover glass. Embryogenesis was followed microscopically with Nomarski interference optics and high-resolution video recording.

  14. 'Good Governance' dan 'Governability'

    Directory of Open Access Journals (Sweden)

    - Pratikno

    2005-03-01

    Full Text Available The article endeavors to trace the outset of governance concept, its dominant meanings and discourse, and its implication towards governability. The central role of government in the governing processes has predominantly been adopted. The concept of governance was emerged precisely in the context of the failure of government as key player in regulation, economic redistribution and political participation. Governance is therefore aimed to emphasize pattern of governing which are based both on democratic mechanism and sound development management. However, practices of such good governance concept –which are mainly adopted and promoted by donor states and agencies– tend to degrade state and/or government authority and legitimacy. Traditional function of the state as sole facilitator of equal societal, political and legal membership among citizens has been diminished. The logic of fair competition has been substituted almost completely by the logic of free competition in nearly all sectors of public life. The concept and practices of good governance have resulted in decayed state authority and failed state which in turn created a condition for "ungovernability". By promoting democratic and humane governance, the article accordingly encourages discourse to reinstall and bring the idea of accountable state back in.

  15. Energy Division progress report, fiscal years 1994--1995

    Energy Technology Data Exchange (ETDEWEB)

    Moser, C.I. [ed.

    1996-06-01

    At ORNL, the Energy Division`s mission is to provide innovative solutions to energy and related issues of national and global importance through interdisciplinary research and development. Its goals and accomplishments are described in this progress report for FY 1994 and FY 1995. The Division`s expenditures in FY 1995 totaled 44.9 million. Sixty percent of the divisions work was supported by the US DOE. Other significant sponsors include the US DOT, the US DOD, other federal agencies, and some private organizations. The Division`s programmatic activities cover three main areas: (1) analysis and assessment, (2) transportation systems, and (3) energy use and delivery technologies. Analysis and assessment activities involve energy and resource analysis, preparation of environmental assessments and impact statements, and impact statements, research on emergency preparedness, analysis of energy and environmental needs in developing countries, and transportation analysis. Transportation systems research seeks to improve the quality of both civilian and military transportation efforts. Energy use and delivery technologies focus on building equipment, building envelopes, (walls, roofs, attics, and materials), improvement of energy efficiency in buildings, and electric power systems.

  16. Plant cells without detectable plastids are generated in the crumpled leaf mutant of Arabidopsis thaliana.

    Science.gov (United States)

    Chen, Yuling; Asano, Tomoya; Fujiwara, Makoto T; Yoshida, Shigeo; Machida, Yasunori; Yoshioka, Yasushi

    2009-05-01

    Plastids are maintained in cells by proliferating prior to cell division and being partitioned to each daughter cell during cell division. It is unclear, however, whether cells without plastids are generated when plastid division is suppressed. The crumpled leaf (crl) mutant of Arabidopsis thaliana is a plastid division mutant that displays severe abnormalities in plastid division and plant development. We show that the crl mutant contains cells lacking detectable plastids; this situation probably results from an unequal partitioning of plastids to each daughter cell. Our results suggest that crl has a partial defect in plastid expansion, which is suggested to be important in the partitioning of plastids to daughter cells when plastid division is suppressed. The absence of cells without detectable plastids in the accumulation and replication of chloroplasts 6 (arc6) mutant, another plastid division mutant of A. thaliana having no significant defects in plant morphology, suggests that the generation of cells without detectable plastids is one of the causes of the developmental abnormalities seen in crl plants. We also demonstrate that plastids with trace or undetectable amounts of chlorophyll are generated from enlarged plastids by a non-binary fission mode of plastid replication in both crl and arc6.

  17. Digital Arithmetic: Division Algorithms

    DEFF Research Database (Denmark)

    Montuschi, Paolo; Nannarelli, Alberto

    2017-01-01

    Division is one of the basic arithmetic operations supported by every computer system. The operation can be performed and implemented by either hardware or software, or by a combination of the two. Although division is not as frequent as addition and multiplication, nowadays, most processors impl...... significant hardware resources and is more suitable for software implementation on the existing multiply units. The purpose of this entry is to provide an introductory survey using a presentation style suitable for the interested non-specialist readers as well....

  18. Power Dissipation in Division

    DEFF Research Database (Denmark)

    Liu, Wei; Nannarelli, Alberto

    2008-01-01

    A few classes of algorithms to implement division in hardware have been used over the years: division by digit-recurrence, by reciprocal approximation by iterative methods and by polynomial approximation. Due to the differences in the algorithms, a comparison among their implementation in terms o...... of performance and precision is sometimes hard to make. In this work, we use power dissipation and energy consumption as metrics to compare among those different classes of algorithms. There are no previous works in the literature presenting such a comparison....

  19. Important projects of the Division

    International Nuclear Information System (INIS)

    2008-01-01

    In this chapter important projects of the Division for Radiation Safety, NPP Decommissioning and Radwaste Management of the VUJE, a. s. are presented. Division for Radiation Safety, NPP Decommissioning and Radwaste Management has successfully carried out variety of significant projects. The most significant projects that were realised, are implemented and possible future projects are introduced in the following part of presentation.

  20. The analysis of the regional self-governing units forests in selected European countries

    Directory of Open Access Journals (Sweden)

    Barbora Lišková

    2013-01-01

    Full Text Available The article focuses on identification, analysis, description and comparison of the regional self-governing units (RSGU forests in selected European countries. The analysis deals not only with forests in the ownership of basic regional self-governing units such as villages but also with forests of higher regional self-governing unit such as regions or federated states. The identification and description of this type of ownership is not overly published in the Czech Republic. The published foreign overall studies and summaries state mainly the division into forests in public and private ownership. This article is created on the basis of the selection of relevant information sources according to corresponding key words. The methods of analysis of available literary sources, conspectus, comparison and interpretation were used to deal with the topic. The quantity of information is higher and more available within basic regional self-governing units than with higher regional self-governing units. On the basis of obtained information it can be stated that the share of forest ownership in the observed countries varies ranging from zero share in the ownership to fifty per cent share in Germany.

  1. The transcriptomes of two heritable cell types illuminate the circuit governing their differentiation.

    Directory of Open Access Journals (Sweden)

    Brian B Tuch

    2010-08-01

    Full Text Available The differentiation of cells into distinct cell types, each of which is heritable for many generations, underlies many biological phenomena. White and opaque cells of the fungal pathogen Candida albicans are two such heritable cell types, each thought to be adapted to unique niches within their human host. To systematically investigate their differences, we performed strand-specific, massively-parallel sequencing of RNA from C. albicans white and opaque cells. With these data we first annotated the C. albicans transcriptome, finding hundreds of novel differentially-expressed transcripts. Using the new annotation, we compared differences in transcript abundance between the two cell types with the genomic regions bound by a master regulator of the white-opaque switch (Wor1. We found that the revised transcriptional landscape considerably alters our understanding of the circuit governing differentiation. In particular, we can now resolve the poor concordance between binding of a master regulator and the differential expression of adjacent genes, a discrepancy observed in several other studies of cell differentiation. More than one third of the Wor1-bound differentially-expressed transcripts were previously unannotated, which explains the formerly puzzling presence of Wor1 at these positions along the genome. Many of these newly identified Wor1-regulated genes are non-coding and transcribed antisense to coding transcripts. We also find that 5' and 3' UTRs of mRNAs in the circuit are unusually long and that 5' UTRs often differ in length between cell-types, suggesting UTRs encode important regulatory information and that use of alternative promoters is widespread. Further analysis revealed that the revised Wor1 circuit bears several striking similarities to the Oct4 circuit that specifies the pluripotency of mammalian embryonic stem cells. Additional characteristics shared with the Oct4 circuit suggest a set of general hallmarks characteristic of

  2. Activity report of Reactor Physics Division : 1990

    International Nuclear Information System (INIS)

    Mohanakrishnan, P.

    1991-01-01

    The major Research and Development and Project activities carried out during the year 1990 in Reactor Physics Division are presented in the form of summaries in this report. The various activities are organised under the following areas : (1) Nuclear Data Evaluation, Processing and Validation, (2) Core Physics and Analysis, (3) Reactor Kinetics and Safety Analysis, (4) Noise Analysis, and (5) Radiation Transport and Shielding. FBTR was restarted in July 1990 and the power was raised upto 500 kW. A number of low power physics experiments on reactivity coefficients, kinetics and noise, neutron flux and gamma dose in B cells, were performed, which are discussed in this report. (author). figs., tabs

  3. E-Division semiannual report. Progress report, June 1--December 31, 1977

    International Nuclear Information System (INIS)

    Kelley, P.A.

    1978-03-01

    The status of the programs and projects of the Electronics Division is reported for the period of June through December 1977. The presentation is divided into three sections: Research, Engineering Support, and Technical Services. Each of these sections presents the activities and accomplishments of the corresponding branch within the Division. The primary goal of the Research and Development branch is to advance technology for future applications. The primary goal of the Engineering Support branch is to apply advanced technology to laboratory and material problems. The primary goal of the Technical Services branch is to provide a technical base and support for Laboratory programs. These goals are reflected in this report. Among the subject areas included are the following: radiation detectors, temperature monitoring, electromagnetic probing, Josephson junction switching devices, fiber optics, high-temperature electronics, HVAC systems, microprocessors, fuel cell-powered vehicles, laser fusion

  4. Changes in radiosensitivity of V-79 cells accompanying growth and cell division

    International Nuclear Information System (INIS)

    Lehnert, S.

    1975-01-01

    The X-ray survival curve for asynchronous Chinese hamster V-79 cells at 17 to 20 hr after plating when cells are irradiated as microclones of two to four cells differs from the survival curve seen at short times after plating, when single cells are irradiated, in having higher D 0 (300 rad vs 160 rad) and negligible extrapolation number. As a consequence of the difference in D 0 the difference in survival between single cells and clones increases with increasing dose. Transient cyclic changes in survival occur at early times after plating and are probably related to partial synchronization induced by trypsinization. In addition there is a progressive increase in survival which develops with increasing time after plating, as the number of cells in the clones increases. Decrease in radiosensitivity with increasing number of cells irradiated is also observed for synchronous cells when cells at corresponding points in the cell cycle are irradiated. Accumulation and repair of sublethal damage is demonstrable in cells irradiated at short times after plating, but cannot be shown at 20 hr after plating when cells are irradiated as microclones. (U.S.)

  5. Stationary infinitely divisible processes

    DEFF Research Database (Denmark)

    Barndorff-Nielsen, Ole E.

    Several recent strands of work has led to the consideration of various types of continuous time stationary and infinitely divisible processes. A review of these types, with some new results, is presented.......Several recent strands of work has led to the consideration of various types of continuous time stationary and infinitely divisible processes. A review of these types, with some new results, is presented....

  6. Chemical Technology Division annual technical report, 1994

    International Nuclear Information System (INIS)

    1995-06-01

    Highlights of the Chemical Technology (CMT) Division's activities during 1994 are presented. In this period, CMT conducted research and development in the following areas: (1) electrochemical technology, including advanced batteries and fuel cells; (2) technology for fluidized-bed combustion; (3) methods for treatment of hazardous waste and mixed hazardous/radioactive waste; (4) the reaction of nuclear waste glass and spent fuel under conditions expected for an unsaturated repository; (5) processes for separating and recovering transuranic elements from waste streams, concentrating radioactive waste streams with advanced evaporator technology, and producing 99 Mo from low-enriched uranium for medical applications; (6) electrometallurgical treatment of the many different types of spent nuclear fuel in storage at Department of Energy sites; and (8) physical chemistry of selected materials in environments simulating those of fission and fusion energy systems. The Division also conducts basic research in catalytic chemistry associated with molecular energy resources and novel ceramic precursors; materials chemistry of superconducting oxides, electrified metal/solution interfaces, molecular sieve structures, and impurities in scrap copper and steel; and the geochemical processes involved in mineral/fluid interfaces and water-rock interactions occurring in active hydrothermal systems. In addition, the Analytical Chemistry Laboratory in CMT provides a broad range of analytical chemistry support services to the technical programs at Argonne National Laboratory (ANL)

  7. Chemical Technology Division, Annual technical report, 1991

    International Nuclear Information System (INIS)

    1992-03-01

    Highlights of the Chemical Technology (CMT) Division's activities during 1991 are presented. In this period, CMT conducted research and development in the following areas: (1) electrochemical technology, including advanced batteries and fuel cells; (2) technology for fluidized-bed combustion and coal-fired magnetohydrodynamics; (3) methods for treatment of hazardous and mixed hazardous/radioactive waste; (4) the reaction of nuclear waste glass and spent fuel under conditions expected for an unsaturated repository; (5) processes for separating and recovering transuranic elements from nuclear waste streams; (6) recovery processes for discharged fuel and the uranium blanket in the Integral Fast Reactor (IFR); (7) processes for removal of actinides in spent fuel from commercial water-cooled nuclear reactors and burnup in IFRs; and (8) physical chemistry of selected materials in environments simulating those of fission and fusion energy systems. The Division also conducts basic research in catalytic chemistry associated with molecular energy resources; chemistry of superconducting oxides and other materials of interest with technological application; interfacial processes of importance to corrosion science, catalysis, and high-temperature superconductivity; and the geochemical processes involved in water-rock interactions occurring in active hydrothermal systems. In addition, the Analytical Chemistry Laboratory in CMT provides a broad range of analytical chemistry support services to the technical programs at Argonne National Laboratory (ANL)

  8. Chemical Technology Division, Annual technical report, 1991

    Energy Technology Data Exchange (ETDEWEB)

    1992-03-01

    Highlights of the Chemical Technology (CMT) Division's activities during 1991 are presented. In this period, CMT conducted research and development in the following areas: (1) electrochemical technology, including advanced batteries and fuel cells; (2) technology for fluidized-bed combustion and coal-fired magnetohydrodynamics; (3) methods for treatment of hazardous and mixed hazardous/radioactive waste; (4) the reaction of nuclear waste glass and spent fuel under conditions expected for an unsaturated repository; (5) processes for separating and recovering transuranic elements from nuclear waste streams; (6) recovery processes for discharged fuel and the uranium blanket in the Integral Fast Reactor (IFR); (7) processes for removal of actinides in spent fuel from commercial water-cooled nuclear reactors and burnup in IFRs; and (8) physical chemistry of selected materials in environments simulating those of fission and fusion energy systems. The Division also conducts basic research in catalytic chemistry associated with molecular energy resources; chemistry of superconducting oxides and other materials of interest with technological application; interfacial processes of importance to corrosion science, catalysis, and high-temperature superconductivity; and the geochemical processes involved in water-rock interactions occurring in active hydrothermal systems. In addition, the Analytical Chemistry Laboratory in CMT provides a broad range of analytical chemistry support services to the technical programs at Argonne National Laboratory (ANL).

  9. Bioethical ambition, political opportunity and the European governance of patenting: the case of human embryonic stem cell science.

    Science.gov (United States)

    Salter, Brian; Salter, Charlotte

    2013-12-01

    Scientific progress in the life sciences is dependent on the governance of tensions between the economic potential of the innovation and the cultural response from society. Ownership of the scientific innovation through patenting is a necessary part of the realization of its economic value yet, in the case of human embryonic stem cell (hESC) science, ownership of the human body and human life may offend fundamental cultural values. In the case of transnational patenting governance by the European Patent Office (EPO) and the European Union (EU), cross-national cultural conflict in the field of hESC science has produced a political demand for a form of governance that can incorporate ethical as well as economic judgements in its decision making. This paper explores how bioethics has responded to this opportunity to establish itself as a form of expert authority for the negotiation and resolution of the cultural conflict. In so doing, it shows how the political struggle that has accompanied this bid for new governance territory has been influenced both by the political tensions between the EPO and EU systems of patenting governance and the resistance of competing experts in law and science to a bioethical presence. Copyright © 2012 Elsevier Ltd. All rights reserved.

  10. Differential transcriptome analysis between Populus and its synthesized allotriploids driven by second-division restitution.

    Science.gov (United States)

    Cheng, Shiping; Huang, Zhen; Li, Yun; Liao, Ting; Suo, Yujing; Zhang, Pingdong; Wang, Jun; Kang, Xiangyang

    2015-12-01

    In this report, we compared transcriptomic differences between a synthetic Populus section Tacamahaca triploid driven by second-division restitution and its parents using a high-throughput RNA-seq method. A total of 4,080 genes were differentially expressed between the high-growth vigor allotriploids (SDR-H) and their parents, and 719 genes were non-additively expressed in SDR-H. Differences in gene expression between the allotriploid and male parent were more significant than those between the allotriploid and female parent, which may be caused by maternal effects. We observed 3,559 differentially expressed genes (DEGs) between the SDR-H and male parent. Notably, the genes were mainly involved in metabolic process, cell proliferation, DNA methylation, cell division, and meristem and developmental growth. Among the 1,056 DEGs between SDR-H and female parent, many genes were associated with metabolic process and carbon utilization. In addition, 1,789 DEGs between high- and low-growth vigor allotriploid were mainly associated with metabolic process, auxin poplar transport, and regulation of meristem growth. Our results indicated that the higher poplar ploidy level can generate extensive transcriptomic diversity compared with its parents. Overall, these results increased our understanding of the driving force for phenotypic variation and adaptation in allopolyploids driven by second-division restitution. © 2015 Institute of Botany, Chinese Academy of Sciences.

  11. Earth Sciences Division collected abstracts: 1979

    International Nuclear Information System (INIS)

    Henry, A.L.; Schwartz, L.L.

    1980-01-01

    This report is a compilation of abstracts of papers, internal reports, and talks presented during 1979 at national and international meetings by members of the Earth Sciences Division, Lawrence Livermore Laboratory. The arrangement is alphabetical (by author). For a given report, a bibliographic reference appears under the name of each coauthor, but the abstract iself is given only under the name of the first author or the first Earth Sciences Division author. A topical index at the end of the report provides useful cross references, while indicating major areas of research interest in the Earth Sciences Division

  12. Chemical Sciences Division annual report 1994

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-06-01

    The division is one of ten LBL research divisions. It is composed of individual research groups organized into 5 scientific areas: chemical physics, inorganic/organometallic chemistry, actinide chemistry, atomic physics, and chemical engineering. Studies include structure and reactivity of critical reaction intermediates, transients and dynamics of elementary chemical reactions, and heterogeneous and homogeneous catalysis. Work for others included studies of superconducting properties of high-{Tc} oxides. In FY 1994, the division neared completion of two end-stations and a beamline for the Advanced Light Source, which will be used for combustion and other studies. This document presents summaries of the studies.

  13. Global constitutionalism, applied to global health governance: uncovering legitimacy deficits and suggesting remedies.

    Science.gov (United States)

    Ooms, Gorik; Hammonds, Rachel

    2016-12-03

    Global constitutionalism is a way of looking at the world, at global rules and how they are made, as if there was a global constitution, empowering global institutions to act as a global government, setting rules which bind all states and people. This essay employs global constitutionalism to examine how and why global health governance, as currently structured, has struggled to advance the right to health, a fundamental human rights obligation enshrined in the International Covenant on Economic, Social and Cultural Rights. It first examines the core structure of the global health governance architecture, and its evolution since the Second World War. Second, it identifies the main constitutionalist principles that are relevant for a global constitutionalism assessment of the core structure of the global health governance architecture. Finally, it applies these constitutionalist principles to assess the core structure of the global health governance architecture. Leading global health institutions are structurally skewed to preserve high incomes countries' disproportionate influence on transnational rule-making authority, and tend to prioritise infectious disease control over the comprehensive realisation of the right to health. A Framework Convention on Global Health could create a classic division of powers in global health governance, with WHO as the law-making power in global health governance, a global fund for health as the executive power, and the International Court of Justice as the judiciary power.

  14. Symbiotic Cell Differentiation and Cooperative Growth in Multicellular Aggregates.

    Directory of Open Access Journals (Sweden)

    Jumpei F Yamagishi

    2016-10-01

    Full Text Available As cells grow and divide under a given environment, they become crowded and resources are limited, as seen in bacterial biofilms and multicellular aggregates. These cells often show strong interactions through exchanging chemicals, as evident in quorum sensing, to achieve mutualism and division of labor. Here, to achieve stable division of labor, three characteristics are required. First, isogenous cells differentiate into several types. Second, this aggregate of distinct cell types shows better growth than that of isolated cells without interaction and differentiation, by achieving division of labor. Third, this cell aggregate is robust with respect to the number distribution of differentiated cell types. Indeed, theoretical studies have thus far considered how such cooperation is achieved when the ability of cell differentiation is presumed. Here, we address how cells acquire the ability of cell differentiation and division of labor simultaneously, which is also connected with the robustness of a cell society. For this purpose, we developed a dynamical-systems model of cells consisting of chemical components with intracellular catalytic reaction dynamics. The reactions convert external nutrients into internal components for cellular growth, and the divided cells interact through chemical diffusion. We found that cells sharing an identical catalytic network spontaneously differentiate via induction from cell-cell interactions, and then achieve division of labor, enabling a higher growth rate than that in the unicellular case. This symbiotic differentiation emerged for a class of reaction networks under the condition of nutrient limitation and strong cell-cell interactions. Then, robustness in the cell type distribution was achieved, while instability of collective growth could emerge even among the cooperative cells when the internal reserves of products were dominant. The present mechanism is simple and general as a natural consequence of

  15. Structure and functional regulation of RipA, a mycobacterial enzyme essential for daughter cell separation.

    Science.gov (United States)

    Ruggiero, Alessia; Marasco, Daniela; Squeglia, Flavia; Soldini, Silvia; Pedone, Emilia; Pedone, Carlo; Berisio, Rita

    2010-09-08

    Cell separation depends on cell-wall hydrolases that cleave the peptidoglycan layer connecting daughter cells. In Mycobacterium tuberculosis, this process is governed by the predicted endopeptidase RipA. In the absence of this enzyme, the bacterium is unable to divide and exhibits an abnormal phenotype. We here report the crystal structure of a relevant portion of RipA, containing its catalytic-domain and an extra-domain of hitherto unknown function. The structure clearly demonstrates that RipA is produced as a zymogen, which needs to be activated to achieve cell-division. Bacterial cell-wall degradation assays and proteolysis experiments strongly suggest that activation occurs via proteolytic processing of a fully solvent exposed loop identified in the crystal structure. Indeed, proteolytic cleavage at this loop produces an activated form, consisting of the sole catalytic domain. Our work provides the first evidence of self-inhibition in cell-disconnecting enzymes and opens a field for the design of novel antitubercular therapeutics. Copyright © 2010 Elsevier Ltd. All rights reserved.

  16. Ciprofloxacin Derivatives Affect Parasite Cell Division and Increase the Survival of Mice Infected with Toxoplasma gondii.

    Directory of Open Access Journals (Sweden)

    Erica S Martins-Duarte

    Full Text Available Toxoplasmosis, caused by the protozoan Toxoplasma gondii, is a worldwide disease whose clinical manifestations include encephalitis and congenital malformations in newborns. Previously, we described the synthesis of new ethyl-ester derivatives of the antibiotic ciprofloxacin with ~40-fold increased activity against T. gondii in vitro, compared with the original compound. Cipro derivatives are expected to target the parasite's DNA gyrase complex in the apicoplast. The activity of these compounds in vivo, as well as their mode of action, remained thus far uncharacterized. Here, we examined the activity of the Cipro derivatives in vivo, in a model of acute murine toxoplasmosis. In addition, we investigated the cellular effects T. gondii tachyzoites in vitro, by immunofluorescence and transmission electron microscopy (TEM. When compared with Cipro treatment, 7-day treatments with Cipro derivatives increased mouse survival significantly, with 13-25% of mice surviving for up to 60 days post-infection (vs. complete lethality 10 days post-infection, with Cipro treatment. Light microscopy examination early (6 and 24h post-infection revealed that 6-h treatments with Cipro derivatives inhibited the initial event of parasite cell division inside host cells, in an irreversible manner. By TEM and immunofluorescence, the main cellular effects observed after treatment with Cipro derivatives and Cipro were cell scission inhibition--with the appearance of 'tethered' parasites--malformation of the inner membrane complex, and apicoplast enlargement and missegregation. Interestingly, tethered daughter cells resulting from Cipro derivatives, and also Cipro, treatment did not show MORN1 cap or centrocone localization. The biological activity of Cipro derivatives against C. parvum, an apicomplexan species that lacks the apicoplast, is, approximately, 50 fold lower than that in T. gondii tachyzoites, supporting that these compounds targets the apicoplast. Our results

  17. Theoretical Division annual report, FY 1975

    International Nuclear Information System (INIS)

    Carruthers, P.A.

    1976-02-01

    This report presents an overview of the activities in the Theoretical Division and a summary of research highlights during FY 1975. It is intended to inform a wide audience about the theoretical work of the LASL and, therefore, contains introductory material which places recent advances in a broader context. The report is organized into two special interest reports: reactor safety research and the Advanced Research Committee, and 11 reports from the T-Division group leaders on the work of their respective groups. Main interests and responsibilities are outlined including the relationship of the group's work to the work of other T-Division groups and other divisions at the Laboratory. The description of research highlights for FY 1975 explains in a fairly simple, straightforward manner the major recent advances and their significance. Each group report is followed by a publication list for FY 1975 (330 references) and a list of talks given outside the Laboratory (140 references). 29 figures

  18. Status and Outlook for the U.S. Non-Automotive Fuel Cell Industry: Impacts of Government Policies and Assessment of Future Opportunities

    Energy Technology Data Exchange (ETDEWEB)

    Greene, David L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Duleep, K. G. [ICF International, Fairfax, VA (United States); Upreti, Girish [Univ. of Tennessee, Knoxville, TN (United States)

    2011-05-15

    Non-Automotive Fuel Cell Industry, Government Policy and Future Opportunities. Fuel cells (FCs)are considered essential future energy technologies by developed and developing economies alike. Several countries, including the United States, Japan, Germany,and South Korea have established publicly funded R&D and market transformation programs to develop viable domestic FC industries for both automotive and nonautomotive applications.

  19. The History of Metals and Ceramics Division

    Energy Technology Data Exchange (ETDEWEB)

    Craig, D.F.

    1999-01-01

    The division was formed in 1946 at the suggestion of Dr. Eugene P. Wigner to attack the problem of the distortion of graphite in the early reactors due to exposure to reactor neutrons, and the consequent radiation damage. It was called the Metallurgy Division and assembled the metallurgical and solid state physics activities of the time which were not directly related to nuclear weapons production. William A. Johnson, a Westinghouse employee, was named Division Director in 1946. In 1949 he was replaced by John H Frye Jr. when the Division consisted of 45 people. He was director during most of what is called the Reactor Project Years until 1973 and his retirement. During this period the Division evolved into three organizational areas: basic research, applied research in nuclear reactor materials, and reactor programs directly related to a specific reactor(s) being designed or built. The Division (Metals and Ceramics) consisted of 204 staff members in 1973 when James R. Weir, Jr., became Director. This was the period of the oil embargo, the formation of the Energy Research and Development Administration (ERDA) by combining the Atomic Energy Commission (AEC) with the Office of Coal Research, and subsequent formation of the Department of Energy (DOE). The diversification process continued when James O. Stiegler became Director in 1984, partially as a result of the pressure of legislation encouraging the national laboratories to work with U.S. industries on their problems. During that time the Division staff grew from 265 to 330. Douglas F. Craig became Director in 1992.

  20. Theoretical physics division

    International Nuclear Information System (INIS)

    Anon.

    1980-01-01

    Research activities of the theoretical physics division for 1979 are described. Short summaries are given of specific research work in the following fields: nuclear structure, nuclear reactions, intermediate energy physics, elementary particles [fr

  1. Atmospheric and Geophysical Sciences Division: Program report, FY 1987

    International Nuclear Information System (INIS)

    1988-05-01

    In 1988 the Atmospheric and Geophysical Sciences Division began its 15th year as a division. As the Division has grown over the years, its modeling capabilities have expanded to include a broad range of time and space scales ranging from hours to years, and from kilometers to global, respectively. For this report, we have chosen to show a subset of results from several projects to illustrate the breadth, depth, and diversity of the modeling activities that are a major part of the Division's research, development, and application efforts. In addition, the recent reorganization of the Division, including the merger of another group with the Division, is described, and the budget, personnel, models, and publications are reviewed. 95 refs., 26 figs., 2 tabs

  2. Couples’ Attitudes, Childbirth, and the Division of Labor

    NARCIS (Netherlands)

    Jansen, Miranda; Liefbroer, Aart C.

    2006-01-01

    In this article, the authors examine effects of partners’ attitudes on the timing of the birth of a first child, the division of domestic labor, the division of child care, and the division of paid labor of couples. They use data from the Panel Study of Social Integration in the Netherlands, which

  3. Radioactive Waste and Clean-up Division

    International Nuclear Information System (INIS)

    Collard, G.

    2001-01-01

    The main objectives of the Radioactive Waste and Clean-up division of SCK-CEN are outlined. The division's programme consists of research, development and demonstration projects and aims to contribute to the objectives of Agenda 21 on sustainable development in the field of radioactive waste and rehabilitation of radioactively contaminated sites

  4. Energy Technology Division research summary -- 1994

    Energy Technology Data Exchange (ETDEWEB)

    1994-09-01

    Research funded primarily by the NRC is directed toward assessing the roles of cyclic fatigue, intergranular stress corrosion cracking, and irradiation-assisted stress corrosion cracking on failures in light water reactor (LWR) piping systems, pressure vessels, and various core components. In support of the fast reactor program, the Division has responsibility for fuel-performance modeling and irradiation testing. The Division has major responsibilities in several design areas of the proposed International Thermonuclear Experimental Reactor (ITER). The Division supports the DOE in ensuring safe shipment of nuclear materials by providing extensive review of the Safety Analysis Reports for Packaging (SARPs). Finally, in the nuclear area they are investigating the safe disposal of spent fuel and waste. In work funded by DOE`s Energy Efficiency and Renewable Energy, the high-temperature superconductivity program continues to be a major focal point for industrial interactions. Coatings and lubricants developed in the division`s Tribology Section are intended for use in transportation systems of the future. Continuous fiber ceramic composites are being developed for high-performance heat engines. Nondestructive testing techniques are being developed to evaluate fiber distribution and to detect flaws. A wide variety of coatings for corrosion protection of metal alloys are being studied. These can increase lifetimes significant in a wide variety of coal combustion and gasification environments.

  5. Queen pheromones: The chemical crown governing insect social life

    DEFF Research Database (Denmark)

    Holman, Luke

    2010-01-01

    Group-living species produce signals that alter the behavior and even the physiology of their social partners. Social insects possess especially sophisticated chemical communication systems that govern every aspect of colony life, including the defining feature of eusociality: reproductive division...... of labor. Current evidence hints at the central importance of queen pheromones, but progress has been hindered by the fact that such pheromones have only been isolated in honeybees. In a pair of papers on the ant Lasius niger, we identified and investigated a queen pheromone regulating worker sterility...... with other studies, these results indicate that queen pheromones are honest signals of quality that simultaneously regulate multiple social behaviors....

  6. Atmospheric and Geophysical Sciences Division Program Report, 1988--1989

    Energy Technology Data Exchange (ETDEWEB)

    1990-06-01

    In 1990, the Atmospheric and Geophysical Sciences Division begins its 17th year as a division. As the Division has grown over the years, its modeling capabilities have expanded to include a broad range of time and space scales ranging from hours to decades and from local to global. Our modeling is now reaching out from its atmospheric focus to treat linkages with the oceans and the land. In this report, we describe the Division's goal and organizational structure. We also provide tables and appendices describing the Division's budget, personnel, models, and publications. 2 figs., 1 tab.

  7. Reversal of an Epigenetic Switch Governing Cell Chaining in Bacillus subtilis by Protein Instability

    Science.gov (United States)

    Chai, Yunrong; Kolter, Roberto; Losick, Richard

    2010-01-01

    Bacillus subtilis forms long chains of cells during growth and biofilm formation. Cell separation is mediated by autolysins, whose genes are under the negative control of a heteromeric complex composed of the proteins SinR and SlrR. Formation of the SinR•SlrR complex is governed by a self-reinforcing, double-negative feedback loop in which SinR represses the gene for SlrR and SlrR, by forming the SinR•SlrR complex, titrates SinR and prevents it from repressing slrR. The loop is a bistable switch and exists in a SlrRLOW state in which autolysin genes are on, and a SlrRHIGH state in which autolysin genes are repressed by SinR•SlrR. Cells in the SlrRLOW state are driven into the SlrRHIGH state by SinI, an antirepressor that binds to and inhibits SinR. However, the mechanism by which cells in the SlrRHIGH state revert back to the SlrRLOW state is unknown. We report that SlrR is proteolytically unstable and present evidence that self-cleavage via a LexA-like autopeptidase and ClpC contribute to its degradation. Cells producing a self-cleavage-resistant mutant of SlrR exhibited more persistent chaining during growth and yielded biofilms with enhanced structural complexity. We propose that degradation of SlrR allows cells to switch from the SlrRHIGH to the SlrRLOW state. PMID:20923420

  8. The intrusive growth of initial cells in re-arangement of cells in cambium of Tilia cordata Mill.

    Directory of Open Access Journals (Sweden)

    Wiesław Włoch

    2014-01-01

    Full Text Available In the cambium of linden producing wood with short period of grain inclination change (2-4 years, the intensive reorientation of cells takes place. This is possible mainly through an intrusive growth of cell ends from one radial file entering space between tangential walls of neighboring file and through unequal periclinal divisions that occur in the "initial surface". The intrusive growth is located on the longitudinal edge of a fusiform cell close to the end, and causes deviation of cell ends in a neighbouring file from the initial surface. Unequal periclinal division divides a cell with a deviated end into two derivatives, unequal in size. The one of them, which inherits the deviated end, leaves the initial surface becoming a xylem or phloem mother cell. This means that the old end is eliminated. The intensity of intrusive growth and unequal periclinal divisions is decisive for the velocity of cambial cell reorientation. The oriented intrusive growth occurs only in the initial cells. For that reason, changes in cell-ends position do not occur within one packet of cells but are distinct between neighbouring packets.

  9. Dynamic ubiquitin signaling in cell cycle regulation.

    Science.gov (United States)

    Gilberto, Samuel; Peter, Matthias

    2017-08-07

    The cell division cycle is driven by a collection of enzymes that coordinate DNA duplication and separation, ensuring that genomic information is faithfully and perpetually maintained. The activity of the effector proteins that perform and coordinate these biological processes oscillates by regulated expression and/or posttranslational modifications. Ubiquitylation is a cardinal cellular modification and is long known for driving cell cycle transitions. In this review, we emphasize emerging concepts of how ubiquitylation brings the necessary dynamicity and plasticity that underlie the processes of DNA replication and mitosis. New studies, often focusing on the regulation of chromosomal proteins like DNA polymerases or kinetochore kinases, are demonstrating that ubiquitylation is a versatile modification that can be used to fine-tune these cell cycle events, frequently through processes that do not involve proteasomal degradation. Understanding how the increasing variety of identified ubiquitin signals are transduced will allow us to develop a deeper mechanistic perception of how the multiple factors come together to faithfully propagate genomic information. Here, we discuss these and additional conceptual challenges that are currently under study toward understanding how ubiquitin governs cell cycle regulation. © 2017 Gilberto and Peter.

  10. Biology Division progress report, October 1, 1991--September 30, 1993

    Energy Technology Data Exchange (ETDEWEB)

    Hartman, F.C.; Cook, J.S.

    1993-10-01

    This Progress Report summarizes the research endeavors of the Biology Division of the Oak Ridge National Laboratory during the period October 1, 1991, through September 30, 1993. The report is structured to provide descriptions of current activities and accomplishments in each of the Division`s major organizational units. Lists of information to convey the entire scope of the Division`s activities are compiled at the end of the report.

  11. Radix-16 Combined Division and Square Root Unit

    DEFF Research Database (Denmark)

    Nannarelli, Alberto

    2011-01-01

    Division and square root, based on the digitrecurrence algorithm, can be implemented in a combined unit. Several implementations of combined division/square root units have been presented mostly for radices 2 and 4. Here, we present a combined radix-16 unit obtained by overlapping two radix-4...... result digit selection functions, as it is normally done for division only units. The latency of the unit is reduced by retiming and low power methods are applied as well. The proposed unit is compared to a radix-4 combined division/square root unit, and to a radix-16 unit, obtained by cascading two...

  12. Materials Sciences Division 1990 annual report

    Energy Technology Data Exchange (ETDEWEB)

    1990-12-31

    This report is the Materials Sciences Division`s annual report. It contains abstracts describing materials research at the National Center for Electron Microscopy, and for research groups in metallurgy, solid-state physics, materials chemistry, electrochemical energy storage, electronic materials, surface science and catalysis, ceramic science, high tc superconductivity, polymers, composites, and high performance metals.

  13. Earth Sciences Division, collected abstracts-1977

    International Nuclear Information System (INIS)

    Quitiquit, W.A.; Ledbetter, G.P.; Henry, A.L.

    1978-01-01

    This report is a compilation of abstracts of papers, internal reports, and talks presented during 1977 at national and international meetings by members of the Earth Sciences Division, Lawrence Livermore Laboratory. It is arranged alphabetically by author and includes a cross-reference by subject indicating the areas of research interest of the Earth Sciences Division

  14. Parallel optoelectronic trinary signed-digit division

    Science.gov (United States)

    Alam, Mohammad S.

    1999-03-01

    The trinary signed-digit (TSD) number system has been found to be very useful for parallel addition and subtraction of any arbitrary length operands in constant time. Using the TSD addition and multiplication modules as the basic building blocks, we develop an efficient algorithm for performing parallel TSD division in constant time. The proposed division technique uses one TSD subtraction and two TSD multiplication steps. An optoelectronic correlator based architecture is suggested for implementation of the proposed TSD division algorithm, which fully exploits the parallelism and high processing speed of optics. An efficient spatial encoding scheme is used to ensure better utilization of space bandwidth product of the spatial light modulators used in the optoelectronic implementation.

  15. An APC:WNT counter-current-like mechanism regulates cell division along the colonic crypt axis: a mechanism that explains how APC mutations induce proliferative abnormalities that drive colon cancer development.

    Directory of Open Access Journals (Sweden)

    Bruce M Boman

    2013-11-01

    Full Text Available APC normally down-regulates WNT signaling in human colon, and APC mutations cause proliferative abnormalities in premalignant crypts leading to colon cancer, but the mechanisms are unclear at the level of spatial and functional organization of the crypt. Accordingly, we postulated a counter-current-like mechanism based on gradients of factors (APC;WNT that regulate colonocyte proliferation along the crypt axis. During crypt renewal, stem cells (SCs at the crypt bottom generate non-SC daughter cells that proliferate and differentiate while migrating upwards. The APC concentration is low at the crypt bottom and high at the top (where differentiated cells reside. WNT signaling, in contrast, is high at the bottom (where SCs reside and low at the top. Given that WNT and APC gradients are counter to one another, we hypothesized that a counter-current-like mechanism exists. Since both APC and WNT signaling components (e.g. survivin are required for mitosis, this mechanism establishes a zone in the lower crypt where conditions are optimal for maximal cell division and mitosis orientation (symmetric versus asymmetric. APC haploinsufficiency diminishes the APC gradient, shifts the proliferative zone upwards, and increases symmetric division, which causes SC overpopulation. In homozygote mutant crypts, these changes are exacerbated. Thus, APC-mutation-induced changes in the counter-current-like mechanism cause expansion of proliferative populations (SCs, rapidly-proliferating cells during tumorigenesis. We propose this mechanism also drives crypt fission, functions in the crypt cycle, and underlies adenoma development. Novel chemoprevention approaches designed to normalize the two gradients and readjust the proliferative zone downwards, might thwart progression of these premalignant changes.

  16. Radiochemistry Division annual progress report : 1992

    International Nuclear Information System (INIS)

    Natarajan, V.; Godbole, S.V.; Iyer, R.H.

    1994-01-01

    The research and development activities of the Radiochemistry Division during 1992 are briefly described in the form of individual summaries grouped under the headings: 1) Nuclear Chemistry, 2) Actinide Chemistry, 3) Spectroscopy, and 4) Instrumentation. A list of publications numbering 95 by the scientific staff of the Division is also included in the report. (author). 35 figs., 56 tabs

  17. Physics division. Progress report, January 1, 1995--December 31, 1996

    International Nuclear Information System (INIS)

    Stewart, M.; Bacon, D.S.; Aine, C.J.; Bartsch, R.R.

    1997-10-01

    This issue of the Physics Division Progress Report describes progress and achievements in Physics Division research during the period January 1, 1995-December 31, 1996. The report covers the five main areas of experimental research and development in which Physics Division serves the needs of Los Alamos National Laboratory and the nation in applied and basic sciences: (1) biophysics, (2) hydrodynamic physics, (3) neutron science and technology, (4) plasma physics, and (5) subatomic physics. Included in this report are a message from the Division Director, the Physics Division mission statement, an organizational chart, descriptions of the research areas of the five groups in the Division, selected research highlights, project descriptions, the Division staffing and funding levels for FY95-FY97, and a list of publications and presentations

  18. Physics division. Progress report, January 1, 1995--December 31, 1996

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, M.; Bacon, D.S.; Aine, C.J.; Bartsch, R.R. [eds.] [comps.] [and others

    1997-10-01

    This issue of the Physics Division Progress Report describes progress and achievements in Physics Division research during the period January 1, 1995-December 31, 1996. The report covers the five main areas of experimental research and development in which Physics Division serves the needs of Los Alamos National Laboratory and the nation in applied and basic sciences: (1) biophysics, (2) hydrodynamic physics, (3) neutron science and technology, (4) plasma physics, and (5) subatomic physics. Included in this report are a message from the Division Director, the Physics Division mission statement, an organizational chart, descriptions of the research areas of the five groups in the Division, selected research highlights, project descriptions, the Division staffing and funding levels for FY95-FY97, and a list of publications and presentations.

  19. Nuclear Chemistry Division annual report FY83

    International Nuclear Information System (INIS)

    Struble, G.

    1983-01-01

    The purpose of the annual reports of the Nuclear Chemistry Division is to provide a timely summary of research activities pursued by members of the Division during the preceding year. Throughout, details are kept to a minimum; readers desiring additional information are encouraged to read the referenced documents or contact the authors. The Introduction presents an overview of the Division's scientific and technical programs. Next is a section of short articles describing recent upgrades of the Division's major facilities, followed by sections highlighting scientific and technical advances. These are grouped under the following sections: nuclear explosives diagnostics; geochemistry and environmental sciences; safeguards technology and radiation effect; and supporting fundamental science. A brief overview introduces each section. Reports on research supported by a particular program are generally grouped together in the same section. The last section lists the scientific, administrative, and technical staff in the Division, along with visitors, consultants, and postdoctoral fellows. It also contains a list of recent publications and presentations. Some contributions to the annual report are classified and only their abstracts are included in this unclassified portion of the report (UCAR-10062-83/1); the full article appears in the classified portion (UCAR-10062-83/2)

  20. The ACS-NUCL Division 50th Anniversary: Introduction

    Energy Technology Data Exchange (ETDEWEB)

    Hobart, David E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-01-10

    The ACS Division of Nuclear Chemistry and Technology was initiated in 1955 as a subdivision of the Division of Industrial and Engineering Chemistry. Probationary divisional status was lifted in 1965. The Division’s first symposium was held in Denver in 1964 and it is fitting that we kicked-off the 50th Anniversary in Denver in the spring of 2015. Listed as a small ACS Division with only about 1,000 members, NUCL’s impact over the past fifty years has been remarkable. National ACS meetings have had many symposia sponsored or cosponsored by NUCL that included Nobel Laureates, U.S. Senators, other high-ranking officials and many students as speakers. The range of subjects has been exceptional as are the various prestigious awards established by the Division. Of major impact has been the past 30 years of the NUCL Nuclear Chemistry Summer Schools to help fill the void of qualified nuclear scientists and technicians. In celebrating the 50th Anniversary we honor the past, celebrate the present and shape the future of the Division and nuclear science and technology. To celebrate this auspicious occasion a commemorative lapel pin has been designed for distribution to NUCL Division members.

  1. 24 CFR 4.36 - Action by the Ethics Law Division.

    Science.gov (United States)

    2010-04-01

    ... violation is material, the Ethics Law Division shall consider the following factors, as applicable: (1) The... 24 Housing and Urban Development 1 2010-04-01 2010-04-01 false Action by the Ethics Law Division... the Ethics Law Division. (a) After review of the Inspector General's report, the Ethics Law Division...

  2. In vitro expansion of the mammary stem/progenitor cell population by xanthosine treatment

    Directory of Open Access Journals (Sweden)

    Choudhary Ratan K

    2012-06-01

    Full Text Available Abstract Background Mammary stem cells are critical for growth and maintenance of the mammary gland and therefore are of considerable interest for improving productivity and efficiency of dairy animals. Xanthosine treatment has been demonstrated to promote expansion of putative mammary stem cells in vivo, and hepatic and hair follicle stem cells in vitro. In the latter, xanthosine promoted the symmetrical division of hepatic and hair follicle stem cells. The objective of this study was to determine if treating primary cultures of bovine mammary epithelial cells (MEC with xanthosine increases the stem/progenitor cell population by promoting symmetrical division of mammary stem cells. Results In vitro treatment with xanthosine increased the population of MEC during the exponential phase of cell growth, reducing the doubling time from 86 h in control cultures to 60 h in xanthosine-treated cultures. The bromodeoxyuridine (BrdU labeling index and the proportion of MEC in S-phase both were increased by xanthosine treatment, indicating that increased cell accretion was due to increased cell proliferation. Analysis of daughter-pairs indicated that xanthosine promoted a shift from asymmetric to symmetric cell division. Moreover, the 30 % increase in symmetric cell division was concomitant with an increase in the proportion of MEC that were positive for a putative stem cell marker (FNDC3B and a trend toward increased telomerase activity. These results suggest that xanthosine treatment in vitro can increase cell proliferation, promote symmetric cell division and enhance stem/progenitor cell activity. Conclusions Xanthosine treatment increased the proliferation rate of bovine MEC in vitro. This was likely to be mediated by an increase in the proportion of stem/progenitor cells in the MEC population due to promotion of symmetrical stem cell division by xanthosine.

  3. Pavement cells and the topology puzzle.

    Science.gov (United States)

    Carter, Ross; Sánchez-Corrales, Yara E; Hartley, Matthew; Grieneisen, Verônica A; Marée, Athanasius F M

    2017-12-01

    D'Arcy Thompson emphasised the importance of surface tension as a potential driving force in establishing cell shape and topology within tissues. Leaf epidermal pavement cells grow into jigsaw-piece shapes, highly deviating from such classical forms. We investigate the topology of developing Arabidopsis leaves composed solely of pavement cells. Image analysis of around 50,000 cells reveals a clear and unique topological signature, deviating from previously studied epidermal tissues. This topological distribution is established early during leaf development, already before the typical pavement cell shapes emerge, with topological homeostasis maintained throughout growth and unaltered between division and maturation zones. Simulating graph models, we identify a heuristic cellular division rule that reproduces the observed topology. Our parsimonious model predicts how and when cells effectively place their division plane with respect to their neighbours. We verify the predicted dynamics through in vivo tracking of 800 mitotic events, and conclude that the distinct topology is not a direct consequence of the jigsaw piece-like shape of the cells, but rather owes itself to a strongly life history-driven process, with limited impact from cell-surface mechanics. © 2017. Published by The Company of Biologists Ltd.

  4. Streptomyces sporulation - Genes and regulators involved in bacterial cell differentiation

    OpenAIRE

    Larsson, Jessica

    2010-01-01

    Streptomycetes are Gram-positive bacteria with a complex developmental life cycle. They form spores on specialized cells called aerial hyphae, and this sporulation involves alterations in growth, morphogenesis and cell cycle processes like cell division and chromosome segregation. Understanding the developmental mechanisms that streptomycetes have evolved for regulating for example cell division is of general interest in bacterial cell biology. It can also be valuable in the design of new dru...

  5. Lead from the center. How to manage divisions dynamically.

    Science.gov (United States)

    Raynor, M E; Bower, J L

    2001-05-01

    Conventional wisdom holds that a company's divisions should be given almost total autonomy--especially under conditions of uncertainty--because they are closer to emerging technologies, customers, and competitors than corporate headquarters could ever be. But research from Michael Raynor and Joseph Bower suggests that the corporate office should be more, not less, directive in turbulent markets. Rapid changes in an industry make it difficult to predict where and when synergies among divisions might emerge. With so many possibilities and such uncertainty, companies can't afford to sacrifice their ability to flexibly execute business strategy. Corporate headquarters must play an active role in defining the scope of division-level strategy, the authors say, so that divisions do not act in ways that undermine opportunities to collaborate in the future. But neither can companies afford to sacrifice the competitiveness of their divisions as stand-alone businesses. In creating corporate-level strategic flexibility, a corporate office must balance the need for divisional autonomy now with the potential need for cooperation in the future. Through an examination of four corporations--Sprint, WPP, Teradyne, and Viacom--the authors challenge traditional approaches to diversification in which a company's divisions are either related (they share resources and collaborate) or unrelated (they compete for resources and operate as stand-alone businesses). They argue that companies should adopt a dynamic approach to cooperation among divisions, enabling varying degrees of relatedness between divisions depending on strategic circumstances. The authors offer four tactics to help executives manage divisions dynamically.

  6. Reactor Engineering Division Material for World Wide Web Pages

    International Nuclear Information System (INIS)

    1996-01-01

    This document presents the home page of the Reactor Engineering Division of Argonne National Laboratory. This WWW site describes the activities of the Division, an introduction to its wide variety of programs and samples of the results of research by people in the division

  7. Using single cell cultivation system for on-chip monitoring of the interdivision timer in Chlamydomonas reinhardtii cell cycle

    Directory of Open Access Journals (Sweden)

    Soloviev Mikhail

    2010-09-01

    Full Text Available Abstract Regulation of cell cycle progression in changing environments is vital for cell survival and maintenance, and different regulation mechanisms based on cell size and cell cycle time have been proposed. To determine the mechanism of cell cycle regulation in the unicellular green algae Chlamydomonas reinhardtii, we developed an on-chip single-cell cultivation system that allows for the strict control of the extracellular environment. We divided the Chlamydomonas cell cycle into interdivision and division phases on the basis of changes in cell size and found that, regardless of the amount of photosynthetically active radiation (PAR and the extent of illumination, the length of the interdivision phase was inversely proportional to the rate of increase of cell volume. Their product remains constant indicating the existence of an 'interdivision timer'. The length of the division phase, in contrast, remained nearly constant. Cells cultivated under light-dark-light conditions did not divide unless they had grown to twice their initial volume during the first light period. This indicates the existence of a 'commitment sizer'. The ratio of the cell volume at the beginning of the division phase to the initial cell volume determined the number of daughter cells, indicating the existence of a 'mitotic sizer'.

  8. Medical Sciences Division report for 1993

    Energy Technology Data Exchange (ETDEWEB)

    1993-12-31

    This year`s Medical Sciences Division (MSD) Report is organized to show how programs in our division contribute to the core competencies of Oak Ridge Institute for Science and Education (ORISE). ORISE`s core competencies in education and training, environmental and safety evaluation and analysis, occupational and environmental health, and enabling research support the overall mission of the US Department of Energy (DOE).

  9. Medical Sciences Division report for 1993

    International Nuclear Information System (INIS)

    1993-01-01

    This year's Medical Sciences Division (MSD) Report is organized to show how programs in our division contribute to the core competencies of Oak Ridge Institute for Science and Education (ORISE). ORISE's core competencies in education and training, environmental and safety evaluation and analysis, occupational and environmental health, and enabling research support the overall mission of the US Department of Energy (DOE)

  10. Pre-disposition and epigenetics govern variation in bacterial survival upon stress.

    Directory of Open Access Journals (Sweden)

    Ming Ni

    Full Text Available Bacteria suffer various stresses in their unpredictable environment. In response, clonal populations may exhibit cell-to-cell variation, hypothetically to maximize their survival. The origins, propagation, and consequences of this variability remain poorly understood. Variability persists through cell division events, yet detailed lineage information for individual stress-response phenotypes is scarce. This work combines time-lapse microscopy and microfluidics to uniformly manipulate the environmental changes experienced by clonal bacteria. We quantify the growth rates and RpoH-driven heat-shock responses of individual Escherichia coli within their lineage context, stressed by low streptomycin concentrations. We observe an increased variation in phenotypes, as different as survival from death, that can be traced to asymmetric division events occurring prior to stress induction. Epigenetic inheritance contributes to the propagation of the observed phenotypic variation, resulting in three-fold increase of the RpoH-driven expression autocorrelation time following stress induction. We propose that the increased permeability of streptomycin-stressed cells serves as a positive feedback loop underlying this epigenetic effect. Our results suggest that stochasticity, pre-disposition, and epigenetic effects are at the source of stress-induced variability. Unlike in a bet-hedging strategy, we observe that cells with a higher investment in maintenance, measured as the basal RpoH transcriptional activity prior to antibiotic treatment, are more likely to give rise to stressed, frail progeny.

  11. Relevance of the nuclear division cycle to radiosensitivity in yeast

    International Nuclear Information System (INIS)

    Brunborg, G.; Williamson, D.H.

    1978-01-01

    To investigate whether the nuclear division cycle could be related to cycle-specific changes in repair of ionizing radiation damage, we have determined the survival curves after γ-irradiation of samples taken frequently from synchronously dividing cultures of Saccharomyces cerevisiae cells. Survival was low in G1 and increased during S, reaching a maximum around the end of the S phase, which was maintained in G2. The shape of the survival curves for samples taken from later stages revealed a rapid cycle-specific drop in the radioresistance of individual cells. A simple model was formulated on the assumption that survival is greatly enhanced by the action of an enzymatic repair mechanism which requires duplicated but unsegregated DNA as a substrate. (orig.) [de

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

    Directory of Open Access Journals (Sweden)

    Maria Kwiatkowska

    2014-01-01

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

  13. 15 CFR 950.8 - Satellite Data Services Division (SDSD).

    Science.gov (United States)

    2010-01-01

    ... 15 Commerce and Foreign Trade 3 2010-01-01 2010-01-01 false Satellite Data Services Division (SDSD... THE ENVIRONMENTAL DATA SERVICE ENVIRONMENTAL DATA AND INFORMATION § 950.8 Satellite Data Services Division (SDSD). The Satellite Data Services Division of the EDIS National Climatic Center provides...

  14. Division of Agriculture

    Science.gov (United States)

    Department of Natural Resources logo, color scheme Department of Natural Resources Division of Agriculture Search Search DNR's site DNR State of Alaska Toggle main menu visibility Agriculture Home Programs Asset Disposals Alaska Caps Progam Board of Agriculture & Conservation Farm To School Program Grants

  15. Publications - Geospatial Data | Alaska Division of Geological &

    Science.gov (United States)

    from rocks collected in the Richardson mining district, Big Delta Quadrangle, Alaska: Alaska Division Island 2009 topography: Alaska Division of Geological & Geophysical Surveys Miscellaneous Publication , Geologic map of portions of the Livengood B-3, B-4, C-3, and C-4 quadrangles, Tolovana mining district

  16. Biology Division progress report, October 1, 1993--September 30, 1995

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-10-01

    This Progress Report summarizes the research endeavors of the Biology Division of the Oak Ridge National Laboratory during the period October 1, 1993, through September 30, 1995. The report is structured to provide descriptions of current activities and accomplishments in each of the Division`s major organizational units. Lists of information to convey the entire scope of the Division`s activities are compiled at the end of the report. Attention is focused on the following research activities: molecular, cellular, and cancer biology; mammalian genetics and development; genome mapping program; and educational activities.

  17. Mechanistic insights of the Min oscillator via cell-free reconstitution and imaging

    Science.gov (United States)

    Mizuuchi, Kiyoshi; Vecchiarelli, Anthony G.

    2018-05-01

    The MinD and MinE proteins of Escherichia coli self-organize into a standing-wave oscillator on the membrane to help align division at mid-cell. When unleashed from cellular confines, MinD and MinE form a spectrum of patterns on artificial bilayers—static amoebas, traveling waves, traveling mushrooms, and bursts with standing-wave dynamics. We recently focused our cell-free studies on bursts because their dynamics recapitulate many features of Min oscillation observed in vivo. The data unveiled a patterning mechanism largely governed by MinE regulation of MinD interaction with membrane. We proposed that the MinD to MinE ratio on the membrane acts as a toggle switch between MinE-stimulated recruitment and release of MinD from the membrane. In this review, we summarize cell-free data on the Min system and expand upon a molecular mechanism that provides a biochemical explanation as to how these two ‘simple’ proteins can form the remarkable spectrum of patterns.

  18. An APC:WNT Counter-Current-Like Mechanism Regulates Cell Division Along the Human Colonic Crypt Axis: A Mechanism That Explains How APC Mutations Induce Proliferative Abnormalities That Drive Colon Cancer Development

    Science.gov (United States)

    Boman, Bruce M.; Fields, Jeremy Z.

    2013-01-01

    APC normally down-regulates WNT signaling in human colon, and APC mutations cause proliferative abnormalities in premalignant crypts leading to colon cancer, but the mechanisms are unclear at the level of spatial and functional organization of the crypt. Accordingly, we postulated a counter-current-like mechanism based on gradients of factors (APC;WNT) that regulate colonocyte proliferation along the crypt axis. During crypt renewal, stem cells (SCs) at the crypt bottom generate non-SC daughter cells that proliferate and differentiate while migrating upwards. The APC concentration is low at the crypt bottom and high at the top (where differentiated cells reside). WNT signaling, in contrast, is high at the bottom (where SCs reside) and low at the top. Given that WNT and APC gradients are counter to one another, we hypothesized that a counter-current-like mechanism exists. Since both APC and WNT signaling components (e.g., survivin) are required for mitosis, this mechanism establishes a zone in the lower crypt where conditions are optimal for maximal cell division and mitosis orientation (symmetric versus asymmetric). APC haploinsufficiency diminishes the APC gradient, shifts the proliferative zone upwards, and increases symmetric division, which causes SC overpopulation. In homozygote mutant crypts, these changes are exacerbated. Thus, APC-mutation-induced changes in the counter-current-like mechanism cause expansion of proliferative populations (SCs, rapidly proliferating cells) during tumorigenesis. We propose this mechanism also drives crypt fission, functions in the crypt cycle, and underlies adenoma development. Novel chemoprevention approaches designed to normalize the two gradients and readjust the proliferative zone downwards, might thwart progression of these premalignant changes. PMID:24224156

  19. Biology and Medicine Division: Annual report 1986

    International Nuclear Information System (INIS)

    1987-04-01

    The Biology and Medicine Division continues to make important contributions in scientific areas in which it has a long-established leadership role. For 50 years the Division has pioneered in the application of radioisotopes and charged particles to biology and medicine. There is a growing emphasis on cellular and molecular applications in the work of all the Division's research groups. The powerful tools of genetic engineering, the use of recombinant products, the analytical application of DNA probes, and the use of restriction fragment length polymorphic DNA are described and proposed for increasing use in the future

  20. Biology and Medicine Division: Annual report 1986

    Energy Technology Data Exchange (ETDEWEB)

    1987-04-01

    The Biology and Medicine Division continues to make important contributions in scientific areas in which it has a long-established leadership role. For 50 years the Division has pioneered in the application of radioisotopes and charged particles to biology and medicine. There is a growing emphasis on cellular and molecular applications in the work of all the Division's research groups. The powerful tools of genetic engineering, the use of recombinant products, the analytical application of DNA probes, and the use of restriction fragment length polymorphic DNA are described and proposed for increasing use in the future.