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Sample records for cell nucleus division

  1. Transfer of a eubacteria-type cell division site-determining factor CrMinD gene to the nucleus from the chloroplast genome in Chlamydomonas reinhardtii

    Institute of Scientific and Technical Information of China (English)

    LIU WeiZhong; HU Yong; ZHANG RunJie; ZHOU WeiWei; ZHU JiaYing; LIU XiangLin; HE YiKun

    2007-01-01

    MinD is a ubiquitous ATPase that plays a crucial role in selection of the division site in eubacteria, chloroplasts, and probably Archaea. In four green algae, Mesostigma viride, Nephroselmis olivacea, Chlorella vulgaris and Prototheca wickerhamii, MinD homologues are encoded in the plastid genome. However, in Arabidopsis, MinD is a nucleus-encoded, chloroplast-targeted protein involved in chloroplast division, which suggests that MinD has been transferred to the nucleus in higher land plants. Yet the lateral gene transfer (LGT) of MinD from plastid to nucleus during plastid evolution remains poorly understood. Here, we identified a nucleus-encoded MinD homologue from unicellular green alga Chlamydomonas reinhardtii, a basal species in the green plant lineage. Overexpression of CrMinD in wild type E. coli inhibited cell division and resulted in the filamentous cell formation, clearly demonstrated the conservation of the MinD protein during the evolution of photosynthetic eukaryotes. The transient expression of CrMinD-egfp confirmed the role of CrMinD protein in the regulation of plastid division. Searching all the published plastid genomic sequences of land plants, no MinD homologues were found, which suggests that the transfer of MinD from plastid to nucleus might have occurred before the evolution of land plants.

  2. [Cortical cytoskeletal ring in prophase II leads to correction of abnormalities of the first meiotic division and to meiotic restitution of pollen mother cell nucleus].

    Science.gov (United States)

    Shamina, N V; Zaporozhchenko, I A; Maksiutova, Iu R; Shatskaia, O A

    2007-01-01

    The deviation of prophase cytoskeletal ring formation was determined during meiotic division in 50% of pollen mother cells (PMCs) in maize haploid No 1498 (Zea mays). At prophase in both meiotic divisions the cytoskeletal ring is formed in cortical region of cytoplasm instead of perinuclear. Sometimes formation of both perinuclear and cortical rings is observed in the same cell. It has been shown that in multinucleate PMCs the cortical ring leads to the consolidation of chromosomes into common spindle and to meiotic restitution.

  3. C. elegans HAM-1 functions in the nucleus to regulate asymmetric neuroblast division.

    Science.gov (United States)

    Leung, Amy; Hua, Khang; Ramachandran, Pavitra; Hingwing, Kyla; Wu, Maria; Koh, Pei Luan; Hawkins, Nancy

    2016-02-01

    All 302 neurons in the C. elegans hermaphrodite arise through asymmetric division of neuroblasts. During embryogenesis, the C. elegans ham-1 gene is required for several asymmetric neuroblast divisions in lineages that generate both neural and apoptotic cells. By antibody staining, endogenous HAM-1 is found exclusively at the cell cortex in many cells during embryogenesis and is asymmetrically localized in dividing cells. Here we show that in transgenic embryos expressing a functional GFP::HAM-1 fusion protein, GFP expression is also detected in the nucleus, in addition to the cell cortex. Consistent with the nuclear localization is the presence of a putative DNA binding winged-helix domain within the N-terminus of HAM-1. Through a deletion analysis we determined that the C-terminus of the protein is required for nuclear localization and we identified two nuclear localization sequences (NLSs). A subcellular fractionation experiment from wild type embryos, followed by Western blotting, revealed that endogenous HAM-1 is primarily found in the nucleus. Our analysis also showed that the N-terminus is necessary for cortical localization. While ham-1 function is essential for asymmetric division in the lineage that generates the PLM mechanosensory neuron, we showed that cortical localization may not required. Thus, our results suggest that there is a nuclear function for HAM-1 in regulating asymmetric neuroblast division and that the requirement for cortical localization may be lineage dependent.

  4. 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

  5. Cell division in apicomplexan parasites.

    Science.gov (United States)

    Francia, Maria E; Striepen, Boris

    2014-02-01

    Toxoplasma gondii and Plasmodium falciparum are important human pathogens. These parasites and many of their apicomplexan relatives undergo a complex developmental process in the cells of their hosts, which includes genome replication, cell division and the assembly of new invasive stages. Apicomplexan cell cycle progression is both globally and locally regulated. Global regulation is carried out throughout the cytoplasm by diffusible factors that include cell cycle-specific kinases, cyclins and transcription factors. Local regulation acts on individual nuclei and daughter cells that are developing inside the mother cell. We propose that the centrosome is a master regulator that physically tethers cellular components and that provides spatial and temporal control of apicomplexan cell division.

  6. A FIBER APPARATUS IN THE NUCLEUS OF THE YEAST CELL

    Science.gov (United States)

    Robinow, C. F.; Marak, J.

    1966-01-01

    The structure and mode of division of the nucleus of budding yeast cells have been studied by phase-contrast microscopy during life and by ordinary microscopy after Helly fixation. The components of the nucleus were differentially stained by the Feulgen procedure, with Giemsa solution after hydrolysis, and with iron alum haematoxylin. New information was obtained in cells fixed in Helly's by directly staining them with 0.005% acid fuchsin in 1% acetic acid in water. Electron micrographs have been made of sections of cells that were first fixed with 3% glutaraldehyde, then divested of their walls with snail juice, and postfixed with osmium tetroxide. Light and electron microscopy have given concordant information about the organization of the yeast nucleus. A peripheral segment of the nucleus is occupied by relatively dense matter (the "peripheral cluster" of Mundkur) which is Feulgen negative. The greater part of the nucleus is filled with fine-grained Feulgen-positive matter of low density in which chromosomes could not be identified. Chromosomes become visible in this region under the light microscope at meiosis. In the chromatin lies a short fiber with strong affinity for acid fuchsin. The nucleus divides by elongation and constriction, and during this process the fiber becomes long and thin. Electron microscopy has resolved it into a bundle of dark-edged 150 to 180 A filaments which extends between "centriolar plaques" that are attached to the nuclear envelope. PMID:5331666

  7. Polarized Cell Division of Chlamydia trachomatis.

    Science.gov (United States)

    Abdelrahman, Yasser; Ouellette, Scot P; Belland, Robert J; Cox, John V

    2016-08-01

    Bacterial cell division predominantly occurs by a highly conserved process, termed binary fission, that requires the bacterial homologue of tubulin, FtsZ. Other mechanisms of bacterial cell division that are independent of FtsZ are rare. Although the obligate intracellular human pathogen Chlamydia trachomatis, the leading bacterial cause of sexually transmitted infections and trachoma, lacks FtsZ, it has been assumed to divide by binary fission. We show here that Chlamydia divides by a polarized cell division process similar to the budding process of a subset of the Planctomycetes that also lack FtsZ. Prior to cell division, the major outer-membrane protein of Chlamydia is restricted to one pole of the cell, and the nascent daughter cell emerges from this pole by an asymmetric expansion of the membrane. Components of the chlamydial cell division machinery accumulate at the site of polar growth prior to the initiation of asymmetric membrane expansion and inhibitors that disrupt the polarity of C. trachomatis prevent cell division. The polarized cell division of C. trachomatis is the result of the unipolar growth and FtsZ-independent fission of this coccoid organism. This mechanism of cell division has not been documented in other human bacterial pathogens suggesting the potential for developing Chlamydia-specific therapeutic treatments.

  8. Asymmetric stem cell division: lessons from Drosophila.

    Science.gov (United States)

    Wu, Pao-Shu; Egger, Boris; Brand, Andrea H

    2008-06-01

    Asymmetric cell division is an important and conserved strategy in the generation of cellular diversity during animal development. Many of our insights into the underlying mechanisms of asymmetric cell division have been gained from Drosophila, including the establishment of polarity, orientation of mitotic spindles and segregation of cell fate determinants. Recent studies are also beginning to reveal the connection between the misregulation of asymmetric cell division and cancer. What we are learning from Drosophila as a model system has implication both for stem cell biology and also cancer research.

  9. [Induced-division of neurons derived from neural stem cells].

    Science.gov (United States)

    Lin, Qiu-Xia; Que, Hai-Ping; Lu, Shuang-Hong; Liu, Shao-Jun

    2004-04-25

    In order to explore if mature neurons derived from neural stem cells have the potentiality to divide, we utilized the chemical digestion method to disperse the adult rat brain tissue into single cells, and culture them in serum-free medium. After being cultured for about eight days in vitro, the neural stem cells were induced to differentiate into neurons. The neurons were further induced to divide. Utilizing the method of serial photograph and NF-160 immunocytochemistry, the processes of division of some neurons were recorded. At the same time, PCNA+NF-160 (or Chat, GABA, GAD) double label were used to investigate if the dividing-neurons were mature ones. After the neural stem cells were induced to differentiate in vitro for eight days, they possessed the shape and character of mature neurons. The differentiated neuron had a big nucleus and one or two distinct nucleolus in the nuclear. Within the perikaryon,there were a large amount of dense and Nissl body-like structure. Several long processes emerged from various locations of the cell body. Then, EGF and bFGF were added into the medium to induce division. After two days of induced-division, neuron-like cells were observed to divide; moreover, the number of neuron-like cells in the region increased continually. Immunocytochemistry demonstrated these cells were NF-160-positive. Serial photographs of dividing-process of neuron-like cells were obtained and their daughter cells were also NF-160-positive. After PCNA+NF-160 (or Chat, GABA, GAD) double label, some cells showed brown cell plasma and black nucleus. The above-mentioned results indicate that neurons, which were previously thought to be end-differentiated, can be re-called into cell cycle under appropriate conditions. Mature neurons still have the potential to divide, proliferate and self-renew.

  10. The fencing problem and Coleochaete cell division.

    Science.gov (United States)

    Wang, Yuandi; Dou, Mingya; Zhou, Zhigang

    2015-03-01

    The findings in this study suggest that the solution of a boundary value problem for differential equation system can be used to discuss the fencing problem in mathematics and Coleochaete, a green algae, cell division. This differential equation model in parametric expression is used to simulate the two kinds of cell division process, one is for the usual case and the case with a "dead" daughter cell.

  11. 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

  12. Cell division activity during apical hook development

    NARCIS (Netherlands)

    Raz, V.; Koornneef, M.

    2001-01-01

    Growth during plant development is predominantly governed by the combined activities of cell division and cell elongation. The relative contribution of both activities controls the growth of a tissue. A fast change in growth is exhibited at the apical hypocotyl of etiolated seedlings where cells gro

  13. Control of apoptosis by asymmetric cell division.

    Directory of Open Access Journals (Sweden)

    Julia Hatzold

    2008-04-01

    Full Text Available Asymmetric cell division and apoptosis (programmed cell death are two fundamental processes that are important for the development and function of multicellular organisms. We have found that the processes of asymmetric cell division and apoptosis can be functionally linked. Specifically, we show that asymmetric cell division in the nematode Caenorhabditis elegans is mediated by a pathway involving three genes, dnj-11 MIDA1, ces-2 HLF, and ces-1 Snail, that directly control the enzymatic machinery responsible for apoptosis. Interestingly, the MIDA1-like protein GlsA of the alga Volvox carteri, as well as the Snail-related proteins Snail, Escargot, and Worniu of Drosophila melanogaster, have previously been implicated in asymmetric cell division. Therefore, C. elegans dnj-11 MIDA1, ces-2 HLF, and ces-1 Snail may be components of a pathway involved in asymmetric cell division that is conserved throughout the plant and animal kingdoms. Furthermore, based on our results, we propose that this pathway directly controls the apoptotic fate in C. elegans, and possibly other animals as well.

  14. Cell Division in the Light of Modeling.

    Science.gov (United States)

    Bellaïche, Yohanns

    2016-09-26

    Theoretical modeling is central to elucidating underlying principles of emergent properties of complex systems. In cell and developmental biology, the last 15 years have witnessed a convergence of empirical and modeling approaches for fresh perspectives. The role of cell division in coordinating size, shape, and fate in particular illustrates the ever-growing impact of modeling.

  15. An electrostatic model for biological cell division

    CERN Document Server

    Faraggi, Eshel

    2010-01-01

    Probably the most fundamental processes for biological systems is their ability to create themselves through the use of cell division and cell differentiation. In this work a simple physical model is proposed for biological cell division. The model consists of a positive ionic gradient across the cell membrane, and concentration of charge at the nodes of the spindle and on the chromosomes. A simple calculation, based on Coulomb's Law, shows that under such circumstances a chromosome will tend to break up to its constituent chromatids and that the chromatids will be separated by a distance that is an order of thirty percent of the distance between the spindle nodes. Further repulsion between the nodes will tend to stretch the cell and eventually break the cell membrane between the separated chromatids, leading to cell division. The importance of this work is in continuing the understanding of the electromagnetic basis of cell division and providing it with an analytical model. A central implication of this and...

  16. Vegetative Cell Division and Nuclear Translocation in Three Algae Species of Netrium (Zygnematales, Chlorophyta

    Directory of Open Access Journals (Sweden)

    DIAN HENDRAYANTI

    2006-03-01

    Full Text Available Three species of Netrium oblongum, N. digitus v. latum, and N. interruptum were studied for their mode in the vegetative cell division and nuclear translocation during mitosis using light and fluorescence microscopy. The process of cell division in the three species began with the prominent constriction at the chloroplast in both semicells about half way from the apex. The constriction of chloroplast was mostly visible in N. digitus v. latum. Soon after nucleus divided, septum was formed across the cell and cytokinesis occurred. Observation with fluorescence microscope showed that the movement of nucleus moved back into the center of daughter cells was not always synchronous. Division of chloroplast in N. oblongum and N. digitus v. latum were different with that of N. interruptum. Chloroplast division in two former species occured following the movement of the nucleus down semicell. However, in N. interruptum, chloroplast divided later after nucleus occupied the position at the center of the daughter cells. Cell restoration started after the completion of mitosis and cytokinesis.

  17. 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.

  18. Cell division in Corynebacterineae

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    Catriona eDonovan

    2014-04-01

    Full Text Available Bacterial cells must coordinate a number of events during the cell cycle. Spatio-temporal regulation of bacterial cytokinesis is indispensable for the production of viable, genetically identical offspring. In many rod-shaped bacteria, precise midcell assembly of the division machinery relies on inhibitory systems such as Min and Noc. In rod-shaped Actinobacteria, for example Corynebacterium glutamicum and Mycobacterium tuberculosis, the divisome assembles in the proximity of the midcell region, however more spatial flexibility is observed compared to Escherichia coli and Bacillus subtilis. Actinobacteria represent a group of bacteria that spatially regulate cytokinesis in the absence of recognizable Min and Noc homologs. The key cell division steps in E. coli and B. subtilis have been subject to intensive study and are well understood. In comparison, only a minimal set of positive and negative regulators of cytokinesis are known in Actinobacteria. Nonetheless, the timing of cytokinesis and the placement of the division septum is coordinated with growth as well as initiation of chromosome replication and segregation. We summarize here the current knowledge on cytokinesis and division site selection in the Actinobacteria suborder Corynebacterineae.

  19. Kinetics of cell division in epidermal maintenance

    CERN Document Server

    Klein, Allon M; Jones, Philip H; Simons, Benjamin D

    2007-01-01

    The rules governing cell division and differentiation are central to understanding the mechanisms of development, aging and cancer. By utilising inducible genetic labelling, recent studies have shown that the clonal population in transgenic mouse epidermis can be tracked in vivo. Drawing on these results, we explain how clonal fate data may be used to infer the rules of cell division and differentiation underlying the maintenance of adult murine tail-skin. We show that the rates of cell division and differentiation may be evaluated by considering the long-time and short-time clone fate data, and that the data is consistent with cells dividing independently rather than synchronously. Motivated by these findings, we consider a mechanism for cancer onset based closely on the model for normal adult skin. By analysing the expected changes to clonal fate in cancer emerging from a simple two-stage mutation, we propose that clonal fate data may provide a novel method for studying the earliest stages of the disease.

  20. Formative cell divisions: principal determinants of plant morphogenesis.

    Science.gov (United States)

    Smolarkiewicz, Michalina; Dhonukshe, Pankaj

    2013-03-01

    Formative cell divisions utilizing precise rotations of cell division planes generate and spatially place asymmetric daughters to produce different cell layers. Therefore, by shaping tissues and organs, formative cell divisions dictate multicellular morphogenesis. In animal formative cell divisions, the orientation of the mitotic spindle and cell division planes relies on intrinsic and extrinsic cortical polarity cues. Plants lack known key players from animals, and cell division planes are determined prior to the mitotic spindle stage. Therefore, it appears that plants have evolved specialized mechanisms to execute formative cell divisions. Despite their profound influence on plant architecture, molecular players and cellular mechanisms regulating formative divisions in plants are not well understood. This is because formative cell divisions in plants have been difficult to track owing to their submerged positions and imprecise timings of occurrence. However, by identifying a spatiotemporally inducible cell division plane switch system applicable for advanced microscopy techniques, recent studies have begun to uncover molecular modules and mechanisms for formative cell divisions. The identified molecular modules comprise developmentally triggered transcriptional cascades feeding onto microtubule regulators that now allow dissection of the hierarchy of the events at better spatiotemporal resolutions. Here, we survey the current advances in understanding of formative cell divisions in plants in the context of embryogenesis, stem cell functionality and post-embryonic organ formation.

  1. Cell Division, Differentiation and Dynamic Clustering

    CERN Document Server

    Kaneko, K; Kaneko, Kunihiko; Yomo, Tetsuya

    1993-01-01

    A novel mechanism for cell differentiation is proposed, based on the dynamic clustering in a globally coupled chaotic system. A simple model with metabolic reaction, active transport of chemicals from media, and cell division is found to show three successive stages with the growth of the number of cells; coherent growth, dynamic clustering, and fixed cell differentiation. At the last stage, disparity in activities, germ line segregation, somatic cell differentiation, and homeochaotic stability against external perturbation are found. Our results, in consistency with the experiments of the preceding paper, imply that cell differentiation can occur without a spatial pattern. From dynamical systems viewpoint, the new concept of ``open chaos" is proposed, as a novel and general scenario for systems with growing numbers of elements, also seen in economics and sociology.A

  2. Effects of Polyhydroxybutyrate Production on Cell Division

    Science.gov (United States)

    Miller, Kathleen; Rahman, Asif; Hadi, Masood Z.

    2015-01-01

    Synthetic biological engineering can be utilized to aide the advancement of improved long-term space flight. The potential to use synthetic biology as a platform to biomanufacture desired equipment on demand using the three dimensional (3D) printer on the International Space Station (ISS) gives long-term NASA missions the flexibility to produce materials as needed on site. Polyhydroxybutyrates (PHBs) are biodegradable, have properties similar to plastics, and can be produced in Escherichia coli using genetic engineering. Using PHBs during space flight could assist mission success by providing a valuable source of biomaterials that can have many potential applications, particularly through 3D printing. It is well documented that during PHB production E. coli cells can become significantly elongated. The elongation of cells reduces the ability of the cells to divide and thus to produce PHB. I aim to better understand cell division during PHB production, through the design, building, and testing of synthetic biological circuits, and identify how to potentially increase yields of PHB with FtsZ overexpression, the gene responsible for cell division. Ultimately, an increase in the yield will allow more products to be created using the 3D printer on the ISS and beyond, thus aiding astronauts in their missions.

  3. Spindle Positioning and Cell Division in Caenorhabditis elegans

    NARCIS (Netherlands)

    Voet, M. van der

    2010-01-01

    During cell division a cell duplicates its genetic material and segregates one intact copy into each daughter cell. However, cell division has many aspects in addition to the propagation of the genome. For instance, some cells divide asymmetrically, which contributes to the generation of cell divers

  4. 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...

  5. 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

  6. Mechanisms of asymmetric cell divisions in Drosophila melanogaster neuroblasts

    Directory of Open Access Journals (Sweden)

    X Jiang

    2014-04-01

    Full Text Available Stem cells possess the properties of self-renewal and differentiation, and mainly rely on two strategies for division, including symmetric and asymmetric cell divisions. In this review, we summarize the latest progress on asymmetric cell divisions in Drosophila melanogaster neuroblasts (NBs, which focus on the establishment of cell polarity, mitotic spindle orientation, the asymmetric segregation of cell fate determinants as well as cell-cycle control. Here we also introduce five major cell fate determinants, including Numb, Prospero, Brat, Miranda, and Pon, which are thought to be unequally segregated to the ganglion mother cells (GMCs and play an important role in the formation of stem cell-derived tumors

  7. (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…

  8. Nonthermal Fluctuations and Mechanics of the Active Cell Nucleus

    CERN Document Server

    Smith, K; Byrd, H; MacKintosh, F C; Kilfoil, M L

    2013-01-01

    We present direct measurements of fluctuations in the nucleus of yeast cells. While prior work has shown these fluctuations to be active and non-thermal in character, their origin and time dependence are not understood. We show that nuclear fluctuations can be quantitatively understood by uncorrelated, active force fluctuations driving a nuclear medium that is dominated by an uncondensed DNA solution, for which we perform rheological measurements on an in vitro model system under similar conditions to what is expected in the nucleus. We conclude that the eukaryotic nucleus of living cells is a nonequilibrium soft material whose fluctuations are actively driven, and are far from thermal in their time dependence.

  9. Novel coiled-coil cell division factor ZapB stimulates Z ring assembly and cell division

    DEFF Research Database (Denmark)

    Ebersbach, Gitte; Galli, Elisa; 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 are regulated. Here, we identify a novel cell division factor ZapB in Escherichia coli that simultaneously stimulates Z ring assembly and cell...

  10. Mitochondrial inheritance is mediated by microtubules in mammalian cell division.

    Science.gov (United States)

    Lawrence, Elizabeth; Mandato, Craig

    2013-11-01

    The mitochondrial network fragments and becomes uniformly dispersed within the cytoplasm when mammalian cells enter mitosis. Such morphology and distribution of mitochondria was previously thought to facilitate the stochastic inheritance of mitochondria by daughter cells. In contrast, we recently reported that mitochondria in dividing mammalian cells are inherited by an ordered mechanism of inheritance mediated by microtubules. We showed that mitochondria are progressively enriched at the cell equator and depleted at the poles throughout division. Furthermore, the mitochondrial distribution during division is dependent on microtubules, indicating an ordered inheritance strategy. The microtubule-mediated positioning of mitochondria in dividing mammalian cells may have functional consequences for cell division and/or mitochondrial inheritance.

  11. Concise Review: Asymmetric Cell Divisions in Stem Cell Biology

    Directory of Open Access Journals (Sweden)

    Florian Murke

    2015-11-01

    Full Text Available Somatic stem cells are rare cells with unique properties residing in many organs and tissues. They are undifferentiated cells responsible for tissue regeneration and homeostasis, and contain both the capacity to self-renew in order to maintain their stem cell potential and to differentiate towards tissue-specific, specialized cells. However, the knowledge about the mechanisms controlling somatic stem cell fate decisions remains sparse. One mechanism which has been described to control daughter cell fates in selected somatic stem cell systems is the process of asymmetric cell division (ACD. ACD is a tightly regulated and evolutionary conserved process allowing a single stem or progenitor cell to produce two differently specified daughter cells. In this concise review, we will summarize and discuss current concepts about the process of ACD as well as different ACD modes. Finally, we will recapitulate the current knowledge and our recent findings about ACD in human hematopoiesis.

  12. 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)

  13. Illuminating traffic control for cell-division planes.

    Science.gov (United States)

    Robatzek, Silke

    2014-01-01

    When a plant cell divides, four related proteins control the trafficking of vesicles and ensure that cargo that is normally recycled to the plasma membrane is instead re-routed to the plane of cell division.

  14. Smurfs have "fused" into the asymmetric division of stem cells

    Institute of Scientific and Technical Information of China (English)

    Steven Y. Cheng; Ying E. Zhang

    2011-01-01

    @@ The asymmetric cell division is the way in which a stem cell divides into one daughter stem cell and one differentiated daughter cell.This process is one of the key principles of developmental biology that ensures the perpetual supply of stem cells while allowing a particular cell lineage to be populated.During Drosophila oogenesis, the fate of the daughter stem cell produced from the asymmetric division of germline stem cells (GSCs) is specified by Decapentaplegic (Dpp), but the other daughter cell has almost equal access to the Dpp signal.

  15. 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...

  16. Entrainment of cell division in phytoplankton with dynamic energy budgets

    Science.gov (United States)

    Muller, Erik B.; Ananthasubramaniam, Bharath; Klanjšček, Tin; Nisbet, Roger M.

    2011-11-01

    We explore the entrainment behavior of cell division in phytoplankton in the context of Dynamic Energy Budget (DEB) theory. In particular, we explore the range of DEB and environmental parameter values within which a cell divides at regular intervals in a periodic light environment with abundant nutrients and investigate the impact of parameter values on the phase of cell division. We consider three types of cells that differ in the evolution of surface area to volume ratio during the cell cycle: cells with a constant shape (isomorphs), cells with a constant surface area (V0-morphs) and cells with a constant surface area to volume ratio (V1-morphs), the latter being the default choice in studies on the population dynamics of unicellular organisms because of its desirable mathematical implications. Only in isomorphs and V0-morphs, however, cell division can be entrained to a periodic light. Regular cell division in V1 is purely coincidental, as it depends on exact choices for parameter values. We attribute this to the fact that V1-morphs lack the negative feedback of size on the dynamics of reserves in V0-morphs and isomorphs. Because entrained isomorphs and V0-morphs divide during the dark hours in our simulations, these two shapes can represent the division behavior of phytoplankton species that complete the cell cycle during the night, such as dinoflagellates and coccolithophores. A description of the division behavior of species completing the cell cycle during the day, such as silicon dependent diatoms and cyanobacteria, requires a more complex model than used in this paper. Furthermore, we explore the robustness of our findings by randomizing model parameters and introducing unevenness in biomass separation between daughter cells during cell division. We conclude that especially the entrainment in V0-morphs is relatively insensitive to perturbations.

  17. Impact of the cell division cycle on gene circuits

    Science.gov (United States)

    Bierbaum, Veronika; Klumpp, Stefan

    2015-12-01

    In growing cells, protein synthesis and cell growth are typically not synchronous, and, thus, protein concentrations vary over the cell division cycle. We have developed a theoretical description of genetic regulatory systems in bacteria that explicitly considers the cell division cycle to investigate its impact on gene expression. We calculate the cell-to-cell variations arising from cells being at different stages in the division cycle for unregulated genes and for basic regulatory mechanisms. These variations contribute to the extrinsic noise observed in single-cell experiments, and are most significant for proteins with short lifetimes. Negative autoregulation buffers against variation of protein concentration over the division cycle, but the effect is found to be relatively weak. Stronger buffering is achieved by an increased protein lifetime. Positive autoregulation can strongly amplify such variation if the parameters are set to values that lead to resonance-like behaviour. For cooperative positive autoregulation, the concentration variation over the division cycle diminishes the parameter region of bistability and modulates the switching times between the two stable states. The same effects are seen for a two-gene mutual-repression toggle switch. By contrast, an oscillatory circuit, the repressilator, is only weakly affected by the division cycle.

  18. 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.

  19. Cell division and death inhibit glassy behaviour of confluent tissues

    CERN Document Server

    Matoz-Fernandez, D A; Sknepnek, Rastko; Barrat, J L; Henkes, S

    2016-01-01

    We investigate the effects of cell division and apopotosis on collective dynamics in two-dimensional epithelial tissues. Our model includes three key ingredients observed across many epithelia, namely cell-cell adhesion, cell death and a cell division process that depends on the surrounding environment. We show a rich non-equilibrium phase diagram depending on the ratio of cell death to cell division and on the adhesion strength. For large apopotosis rates, cells die out and the tissue disintegrates. As the death rate decreases, however, we show, consecutively, the existence of a gas-like phase, a gel-like phase, and a dense confluent (tissue) phase. Most striking is the observation that the tissue is self-melting through its own internal activity, ruling out the existence of any glassy phase.

  20. Fluidization of tissues by cell division and apoptosis.

    Science.gov (United States)

    Ranft, Jonas; Basan, Markus; Elgeti, Jens; Joanny, Jean-François; Prost, Jacques; Jülicher, Frank

    2010-12-07

    During the formation of tissues, cells organize collectively by cell division and apoptosis. The multicellular dynamics of such systems is influenced by mechanical conditions and can give rise to cell rearrangements and movements. We develop a continuum description of tissue dynamics, which describes the stress distribution and the cell flow field on large scales. In the absence of division and apoptosis, we consider the tissue to behave as an elastic solid. Cell division and apoptosis introduce stress sources that, in general, are anisotropic. By combining cell number balance with dynamic equations for the stress source, we show that the tissue effectively behaves as a viscoelastic fluid with a relaxation time set by the rates of division and apoptosis. If the system is confined in a fixed volume, it reaches a homeostatic state in which division and apoptosis balance. In this state, cells undergo a diffusive random motion driven by the stochasticity of division and apoptosis. We calculate the expression for the effective diffusion coefficient as a function of the tissue parameters and compare our results concerning both diffusion and viscosity to simulations of multicellular systems using dissipative particle dynamics.

  1. Oriented cell divisions in the extending germband of Drosophila.

    Science.gov (United States)

    da Silva, Sara Morais; Vincent, Jean-Paul

    2007-09-01

    Tissue elongation is a general feature of morphogenesis. One example is the extension of the germband, which occurs during early embryogenesis in Drosophila. In the anterior part of the embryo, elongation follows from a process of cell intercalation. In this study, we follow cell behaviour at the posterior of the extending germband. We find that, in this region, cell divisions are mostly oriented longitudinally during the fast phase of elongation. Inhibiting cell divisions prevents longitudinal deformation of the posterior region and leads to an overall reduction in the rate and extent of elongation. Thus, as in zebrafish embryos, cell intercalation and oriented cell division together contribute to tissue elongation. We also show that the proportion of longitudinal divisions is reduced when segmental patterning is compromised, as, for example, in even skipped (eve) mutants. Because polarised cell intercalation at the anterior germband also requires segmental patterning, a common polarising cue might be used for both processes. Even though, in fish embryos, both mechanisms require the classical planar cell polarity (PCP) pathway, germband extension and oriented cell divisions proceed normally in embryos lacking dishevelled (dsh), a key component of the PCP pathway. An alternative means of planar polarisation must therefore be at work in the embryonic epidermis.

  2. Incorporation of mammalian actin into microfilaments in plant cell nucleus

    Directory of Open Access Journals (Sweden)

    Paves Heiti

    2004-04-01

    Full Text Available Abstract Background Actin is an ancient molecule that shows more than 90% amino acid homology between mammalian and plant actins. The regions of the actin molecule that are involved in F-actin assembly are largely conserved, and it is likely that mammalian actin is able to incorporate into microfilaments in plant cells but there is no experimental evidence until now. Results Visualization of microfilaments in onion bulb scale epidermis cells by different techniques revealed that rhodamine-phalloidin stained F-actin besides cytoplasm also in the nuclei whereas GFP-mouse talin hybrid protein did not enter the nuclei. Microinjection of fluorescently labeled actin was applied to study the presence of nuclear microfilaments in plant cells. Ratio imaging of injected fluorescent rabbit skeletal muscle actin and phalloidin staining of the microinjected cells showed that mammalian actin was able to incorporate into plant F-actin. The incorporation occurred preferentially in the nucleus and in the perinuclear region of plant cells whereas part of plant microfilaments, mostly in the periphery of cytoplasm, did not incorporate mammalian actin. Conclusions Microinjected mammalian actin is able to enter plant cell's nucleus, whereas incorporation of mammalian actin into plant F-actin occurs preferentially in the nucleus and perinuclear area.

  3. Defect driven shapes in nematic droplets: analogies with cell division

    CERN Document Server

    Leoni, Marco; Bowick, Mark J; Marchetti, M Cristina

    2016-01-01

    Building on the striking similarity between the structure of the spindle during mitosis in living cells and nematic textures in confined liquid crystals, we use a continuum model of two-dimensional nematic liquid crystal droplets, to examine the physical aspects of cell division. The model investigates the interplay between bulk elasticity of the microtubule assembly, described as a nematic liquid crystal, and surface elasticity of the cell cortex, modelled as a bounding flexible membrane, in controlling cell shape and division. The centrosomes at the spindle poles correspond to the cores of the topological defects required to accommodate nematic order in a closed geometry. We map out the progression of both healthy bipolar and faulty multi-polar division as a function of an effective parameter that incorporates active processes and controls centrosome separation. A robust prediction, independent of energetic considerations, is that the transition from a single cell to daughters cells occurs at critical value...

  4. A mechanistic stochastic framework for regulating bacterial cell division.

    Science.gov (United States)

    Ghusinga, Khem Raj; Vargas-Garcia, Cesar A; Singh, Abhyudai

    2016-07-26

    How exponentially growing cells maintain size homeostasis is an important fundamental problem. Recent single-cell studies in prokaryotes have uncovered the adder principle, where cells add a fixed size (volume) from birth to division, irrespective of their size at birth. To mechanistically explain the adder principle, we consider a timekeeper protein that begins to get stochastically expressed after cell birth at a rate proportional to the volume. Cell-division time is formulated as the first-passage time for protein copy numbers to hit a fixed threshold. Consistent with data, the model predicts that the noise in division timing increases with size at birth. Intriguingly, our results show that the distribution of the volume added between successive cell-division events is independent of the newborn cell size. This was dramatically seen in experimental studies, where histograms of the added volume corresponding to different newborn sizes collapsed on top of each other. The model provides further insights consistent with experimental observations: the distribution of the added volume when scaled by its mean becomes invariant of the growth rate. In summary, our simple yet elegant model explains key experimental findings and suggests a mechanism for regulating both the mean and fluctuations in cell-division timing for controlling size.

  5. 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

    exhibited a synthetic sick phenotype and aberrant cell divisions. The crystal structure showed that ZapB exists as a dimer that is 100% coiled-coil. In vitro, ZapB self-assembled into long filaments and bundles. These results raise the possibility that ZapB stimulates Z ring formation directly via its......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...

  6. Ultrastructure and Membrane Traffic During Cell Division in the Marine Pennate Diatom Phaeodactylum tricornutum.

    Science.gov (United States)

    Tanaka, Atsuko; De Martino, Alessandra; Amato, Alberto; Montsant, Anton; Mathieu, Benjamin; Rostaing, Philippe; Tirichine, Leila; Bowler, Chris

    2015-11-01

    The marine pennate diatom Phaeodactylum tricornutum has become a model for diatom biology, due to its ease of culture and accessibility to reverse genetics approaches. While several features underlying the molecular mechanisms of cell division have been described, morphological analyses are less advanced than they are in other diatoms. We therefore examined cell ultrastructure changes prior to and during cytokinesis. Following chloroplast division, cleavage furrows are formed at both longitudinal ends of the cell and are accompanied by significant vesicle transport. Although neither spindle nor microtubules were observed, the nucleus appeared to be split by the furrow after duplication of the Golgi apparatus. Finally, centripetal cytokinesis was completed by fusion of the furrows. Additionally, F-actin formed a ring structure and its diameter became smaller, accompanying the ingrowing furrows. To further analyse vesicular transport during cytokinesis, we generated transgenic cells expressing yellow fluorescent protein (YFP) fusions with putative diatom orthologs of small GTPase Sec4 and t-SNARE protein SyntaxinA. Time-lapse observations revealed that SyntaxinA-YFP localization expands from both cell tips toward the center, whereas Sec4-YFP was found in the Golgi and subsequently relocalizes to the future division plane. This work provides fundamental new information about cell replication processes in P. tricornutum.

  7. On the chronology and topography of bacterial cell division.

    Science.gov (United States)

    Vicente, M; Palacios, P; Dopazo, A; Garrido, T; Pla, J; Aldea, M

    1991-01-01

    Gene products that play a role in the formation of cell septum should be expected to be endowed with a set of specific properties. In principle, septal proteins should be located at the cell envelope. The expression of division genes should ensure the synthesis of septal proteins at levels commensurate with the needs of cell division at different rates of cell duplication. We have results indicating that some fts genes located within the 2.5-min cluster in the Escherichia coli chromosome conform to these predictions.

  8. Indole prevents Escherichia coli cell division by modulating membrane potential

    OpenAIRE

    Chimerel, Catalin; Field, Christopher M.; Piñero-Fernandez, Silvia; Keyser, Ulrich F.; Summers, David K.

    2012-01-01

    Indole is a bacterial signalling molecule that blocks E. coli cell division at concentrations of 3–5 mM. We have shown that indole is a proton ionophore and that this activity is key to the inhibition of division. By reducing the electrochemical potential across the cytoplasmic membrane of E. coli, indole deactivates MinCD oscillation and prevents formation of the FtsZ ring that is a prerequisite for division. This is the first example of a natural ionophore regulating a key biological proces...

  9. Asymmetric cell division in Mycobacterium tuberculosis and its unique features.

    Science.gov (United States)

    Vijay, Srinivasan; Nagaraja, Mukkayyan; Sebastian, Jees; Ajitkumar, Parthasarathi

    2014-03-01

    Recently, several reports showed that about 80 % of mid-log phase Mycobacterium smegmatis, Mycobacterium marinum, and Mycobacterium bovis BCG cells divide symmetrically with 5-10 % deviation in the septum position from the median. However, the mode of cell division of the pathogenic mycobacterial species, Mycobacterium tuberculosis, remained unclear. Therefore, in the present study, using electron microscopy, fluorescence microscopy of septum- and nucleoid-stained live and fixed cells, and live cell time-lapse imaging, we show the occurrence of asymmetric cell division with unusually deviated septum/constriction in 20 % of the 15 % septating M. tuberculosis cells in the mid-log phase population. The remaining 80 % of the 15 % septating cells divided symmetrically but with 2-5 % deviation in the septum/constriction position, as reported for M. smegmatis, M. marinum, and M. bovis BCG cells. Both the long and the short portions of the asymmetrically dividing M. tuberculosis cells with unusually deviated septum contained nucleoids, thereby generating viable short and long cells from each asymmetric division. M. tuberculosis short cells were acid fast positive and, like the long cells, further readily underwent growth and division to generate micro-colony, thereby showing that they were neither mini cells, spores nor dormant forms of mycobacteria. The freshly diagnosed pulmonary tuberculosis patients' sputum samples, which are known for the prevalence of oxidative stress conditions, also contained short cells at the same proportion as that in the mid-log phase population. The probable physiological significance of the generation of the short cells through unusually deviated asymmetric cell division is discussed.

  10. 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.

  11. 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.

  12. A mirror-symmetric cell division that orchestrates neuroepithelial morphogenesis.

    Science.gov (United States)

    Tawk, Marcel; Araya, Claudio; Lyons, Dave A; Reugels, Alexander M; Girdler, Gemma C; Bayley, Philippa R; Hyde, David R; Tada, Masazumi; Clarke, Jonathan D W

    2007-04-12

    The development of cell polarity is an essential prerequisite for tissue morphogenesis during embryogenesis, particularly in the development of epithelia. In addition, oriented cell division can have a powerful influence on tissue morphogenesis. Here we identify a novel mode of polarized cell division that generates pairs of neural progenitors with mirror-symmetric polarity in the developing zebrafish neural tube and has dramatic consequences for the organization of embryonic tissue. We show that during neural rod formation the polarity protein Pard3 is localized to the cleavage furrow of dividing progenitors, and then mirror-symmetrically inherited by the two daughter cells. This allows the daughter cells to integrate into opposite sides of the developing neural tube. Furthermore, these mirror-symmetric divisions have powerful morphogenetic influence: when forced to occur in ectopic locations during neurulation, they orchestrate the development of mirror-image pattern formation and the consequent generation of ectopic neural tubes.

  13. Nucleus- and cell-specific gene expression in monkey thalamus.

    Science.gov (United States)

    Murray, Karl D; Choudary, Prabhakara V; Jones, Edward G

    2007-02-06

    Nuclei of the mammalian thalamus are aggregations of neurons with unique architectures and input-output connections, yet the molecular determinants of their organizational specificity remain unknown. By comparing expression profiles of thalamus and cerebral cortex in adult rhesus monkeys, we identified transcripts that are unique to dorsal thalamus or to individual nuclei within it. Real-time quantitative PCR and in situ hybridization analyses confirmed the findings. Expression profiling of individual nuclei microdissected from the dorsal thalamus revealed additional subsets of nucleus-specific genes. Functional annotation using Gene Ontology (GO) vocabulary and Ingenuity Pathways Analysis revealed overrepresentation of GO categories related to development, morphogenesis, cell-cell interactions, and extracellular matrix within the thalamus- and nucleus-specific genes, many involved in the Wnt signaling pathway. Examples included the transcription factor TCF7L2, localized exclusively to excitatory neurons; a calmodulin-binding protein PCP4; the bone extracellular matrix molecules SPP1 and SPARC; and other genes involved in axon outgrowth and cell matrix interactions. Other nucleus-specific genes such as CBLN1 are involved in synaptogenesis. The genes identified likely underlie nuclear specification, cell phenotype, and connectivity during development and their maintenance in the adult thalamus.

  14. Leishmania amazonensis Promastigotes Present Two Distinct Modes of Nucleus and Kinetoplast Segregation during Cell Cycle

    Science.gov (United States)

    da Silva, Marcelo Santos; Monteiro, Jomar Patrício; Nunes, Vinícius Santana; Vasconcelos, Elton José; Perez, Arina Marina; Freitas-Júnior, Lúcio de Holanda; Elias, Maria Carolina; Cano, Maria Isabel Nogueira

    2013-01-01

    Here, we show the morphological events associated with organelle segregation and their timing in the cell cycle of a reference strain of Leishmania (L.) amazonensis promastigotes, the main causative agent of Tegumentary leishmaniasis in the Americas. We show evidences that during the cell cycle, L. amazonensis promastigotes present two distinct modes of nucleus and kinetoplast segregation, which occur in different temporal order in different proportions of cells. We used DAPI-staining and EdU-labeling to monitor the segregation of DNA-containing organelles and DNA replication in wild-type parasites. The emergence of a new flagellum was observed using a specific monoclonal antibody. The results show that L. amazonensis cell cycle division is peculiar, with 65% of the dividing cells duplicating the kinetoplast before the nucleus, and the remaining 35% doing the opposite or duplicating both organelles concomitantly. In both cases, the new flagellum appeared during S to G2 phase in 1N1K cells and thus before the segregation of both DNA-containing organelles; however, we could not determine the exact timing of flagellar synthesis. Most of these results were confirmed by the synchronization of parasites using hydroxyurea. Altogether, our data show that during the cell cycle of L. amazonensis promastigotes, similarly to L. donovani, the segregation of nucleus and kinetoplast do not follow a specific order, especially when compared to other trypanosomatids, reinforcing the idea that this characteristic seems to be species-specific and may represent differences in cellular biology among members of the Leishmania genus. PMID:24278433

  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. Constriction and septation during cell division in caulobacters.

    Science.gov (United States)

    Poindexter, J S; Hagenzieker, J G

    1981-07-01

    Morphogenesis of the division site in caulobacters had been described as constrictive in Caulobacter spp. and septate in Asticcacaulis excentricus. However, subsequent studies of other gram-negative genera had implied that constrictive division was an artefact resulting from inadequate preservation of septa; exploration of alternatives to osmium fixation, particularly with aldehydes, was recommended. In this study, the appearance of sectioned division sites was reinvestigated in caulobacter cells prepared by 20 different procedures varying with respect to fixation agents, media, schedules, and temperatures, to dehydrating agents, and to embedding resins. Three types of division site morphogenesis were observed: constriction in C. bacteroides and C. crescentus, partial septation in C. leidyi, and complete, undivided septation in A. excentricus and A. biprosthecum. The anatomy of the division site depended on the bacterial strain, not on the method of preparation of the cells for sectioning. These studies confirm the earlier observations on osmium-fixed caulobacter cells and lead to the general conclusion that gram-negative bacteria with tapered poles probably divide by constriction, whereas septation results in blunt cell poles. A pattern of spiral, rather than circular, insertion of new envelope subunits at the cell equator is proposed as a basic developmental difference between constrictive and septate fission in gram-negative bacteria. Since caulobacter prosthecae can develop as extensions of tapered poles formed by constriction, whereas subpolar or lateral prosthecae occur in species with blunt poles resulting from septation, the site of formation of a thick septum appears unsuitable as a site of subsequent envelope outgrowth.

  17. Relevant parameters in models of cell division control

    CERN Document Server

    Grilli, Jacopo; Kennard, Andrew S; Lagomarsino, Marco Cosentino

    2016-01-01

    A recent burst of dynamic single-cell growth-division data makes it possible to characterize the stochastic dynamics of cell division control in bacteria. Different modeling frameworks were used to infer specific mechanisms from such data, but the links between frameworks are poorly explored, with relevant consequences for how well any particular mechanism can be supported by the data. Here, we describe a simple and generic framework in which two common formalisms can be used interchangeably: (i) a continuous-time division process described by a hazard function and (ii) a discrete-time equation describing cell size across generations (where the unit of time is a cell cycle). In our framework, this second process is a discrete-time Langevin equation with a simple physical analogue. By perturbative expansion around the mean initial size (or inter-division time), we show explicitly how this framework describes a wide range of division control mechanisms, including combinations of time and size control, as well a...

  18. On robustness of phase resetting to cell division under entrainment.

    Science.gov (United States)

    Ahmed, Hafiz; Ushirobira, Rosane; Efimov, Denis

    2015-12-21

    The problem of phase synchronization for a population of genetic oscillators (circadian clocks, synthetic oscillators, etc.) is considered in this paper, taking into account a cell division process and a common entrainment input in the population. The proposed analysis approach is based on the Phase Response Curve (PRC) model of an oscillator (the first order reduced model obtained for the linearized system and inputs with infinitesimal amplitude). The occurrence of cell division introduces state resetting in the model, placing it in the class of hybrid systems. It is shown that without common entraining input in all oscillators, the cell division acts as a disturbance causing phase drift, while the presence of entrainment guarantees boundedness of synchronization phase errors in the population. The performance of the obtained solutions is demonstrated via computer experiments for two different models of circadian/genetic oscillators (Neurospora׳s circadian oscillation model and the repressilator).

  19. Indole prevents Escherichia coli cell division by modulating membrane potential.

    Science.gov (United States)

    Chimerel, Catalin; Field, Christopher M; Piñero-Fernandez, Silvia; Keyser, Ulrich F; Summers, David K

    2012-07-01

    Indole is a bacterial signalling molecule that blocks E. coli cell division at concentrations of 3-5 mM. We have shown that indole is a proton ionophore and that this activity is key to the inhibition of division. By reducing the electrochemical potential across the cytoplasmic membrane of E. coli, indole deactivates MinCD oscillation and prevents formation of the FtsZ ring that is a prerequisite for division. This is the first example of a natural ionophore regulating a key biological process. Our findings have implications for our understanding of membrane biology, bacterial cell cycle control and potentially for the design of antibiotics that target the cell membrane.

  20. Oriented cell division affects the global stress and cell packing geometry of a monolayer under stretch.

    Science.gov (United States)

    Xu, Guang-Kui; Liu, Yang; Zheng, Zhaoliang

    2016-02-01

    Cell division plays a vital role in tissue morphogenesis and homeostasis, and the division plane is crucial for cell fate. For isolated cells, extensive studies show that the orientation of divisions is sensitive to cell shape and the direction of extrinsic mechanical forces. However, it is poorly understood that how the cell divides within a cell monolayer and how the local stress change, due to the division, affects the global stress of epithelial monolayers. Here, we use the vertex dynamics models to investigate the effects of division orientation on the configurations and mechanics of a cell monolayer under stretch. We examine three scenarios of the divisions: dividing along the stretch axis, dividing along the geometric long axis of cells, and dividing at a random angle. It is found that the division along the long cell axis can induce the minimal energy difference, and the global stress of the monolayer after stretch releases more rapidly in this case. Moreover, the long-axis division can result in more random cell orientations and more isotropic cell shapes within the monolayer, comparing with other two cases. This study helps understand the division orientation of cells within a monolayer under mechanical stimuli, and may shed light on linking individual cell's behaviors to the global mechanics and patterns of tissues.

  1. 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 wh

  2. Circadian clocks and cell division: What's the pacemaker?

    OpenAIRE

    Johnson, Carl Hirschie

    2010-01-01

    Evolution has selected a system of two intertwined cell cycles: the cell division cycle (CDC) and the daily (circadian) biological clock. The circadian clock keeps track of solar time and programs biological processes to occur at environmentally appropriate times. One of these processes is the CDC, which is often gated by the circadian clock. The intermeshing of these two cell cycles is probably responsible for the observation that disruption of the circadian system enhances susceptibility to...

  3. Planar cell polarity signalling controls cell division orientation during zebrafish gastrulation.

    Science.gov (United States)

    Gong, Ying; Mo, Chunhui; Fraser, Scott E

    2004-08-05

    Oriented cell division is an integral part of pattern development in processes ranging from asymmetric segregation of cell-fate determinants to the shaping of tissues. Despite proposals that it has an important function in tissue elongation, the mechanisms regulating division orientation have been little studied outside of the invertebrates Caenorhabditis elegans and Drosophila melanogaster. Here, we have analysed mitotic divisions during zebrafish gastrulation using in vivo confocal imaging and found that cells in dorsal tissues preferentially divide along the animal-vegetal axis of the embryo. Establishment of this animal-vegetal polarity requires the Wnt pathway components Silberblick/Wnt11, Dishevelled and Strabismus. Our findings demonstrate an important role for non-canonical Wnt signalling in oriented cell division during zebrafish gastrulation, and indicate that oriented cell division is a driving force for axis elongation. Furthermore, we propose that non-canonical Wnt signalling has a conserved role in vertebrate axis elongation, orienting both cell intercalation and mitotic division.

  4. Harnessing single cell sorting to identify cell division genes and regulators in bacteria.

    Directory of Open Access Journals (Sweden)

    Catherine Burke

    Full Text Available Cell division is an essential cellular process that requires an array of known and unknown proteins for its spatial and temporal regulation. Here we develop a novel, high-throughput screening method for the identification of bacterial cell division genes and regulators. The method combines the over-expression of a shotgun genomic expression library to perturb the cell division process with high-throughput flow cytometry sorting to screen many thousands of clones. Using this approach, we recovered clones with a filamentous morphology for the model bacterium, Escherichia coli. Genetic analysis revealed that our screen identified both known cell division genes, and genes that have not previously been identified to be involved in cell division. This novel screening strategy is applicable to a wide range of organisms, including pathogenic bacteria, where cell division genes and regulators are attractive drug targets for antibiotic development.

  5. Mitochondrial dynamics and inheritance during cell division, development and disease.

    Science.gov (United States)

    Mishra, Prashant; Chan, David C

    2014-10-01

    During cell division, it is critical to properly partition functional sets of organelles to each daughter cell. The partitioning of mitochondria shares some common features with that of other organelles, particularly in the use of interactions with cytoskeletal elements to facilitate delivery to the daughter cells. However, mitochondria have unique features - including their own genome and a maternal mode of germline transmission - that place additional demands on this process. Consequently, mechanisms have evolved to regulate mitochondrial segregation during cell division, oogenesis, fertilization and tissue development, as well as to ensure the integrity of these organelles and their DNA, including fusion-fission dynamics, organelle transport, mitophagy and genetic selection of functional genomes. Defects in these processes can lead to cell and tissue pathologies.

  6. 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, incl

  7. How to Foster an Understanding of Growth and Cell Division

    Science.gov (United States)

    Kruger, Dirk; Fleige, Jennifer; Riemeier, Tanja

    2006-01-01

    The study presents the frequencies of students' conceptions of growth and cell division before and after one hour of instruction. The investigation supplements qualitative results by directing attention to those conceptions which might occur most frequently to students: teachers can then concentrate their preparation on practical requirements. A…

  8. Bacterial Cell Wall Growth, Shape and Division

    NARCIS (Netherlands)

    Derouaux, A.; Terrak, M.; den Blaauwen, T.; Vollmer, W.; Remaut, H.; Fronzes, R.

    2014-01-01

    The shape of a bacterial cell is maintained by its peptidoglycan sacculus that completely surrounds the cytoplasmic membrane. During growth the sacculus is enlarged by peptidoglycan synthesis complexes that are controlled by components linked to the cytoskeleton and, in Gram-negative bacteria, by ou

  9. Nucleus pulposus cell-matrix interactions with laminins.

    Science.gov (United States)

    Gilchrist, C L; Francisco, A T; Plopper, G E; Chen, J; Setton, L A

    2011-06-20

    The cells of the nucleus pulposus (NP) region of the intervertebral disc play a critical role in this tissue's generation and maintenance, and alterations in NP cell viability, metabolism, and phenotype with aging may be key contributors to progressive disc degeneration. Relatively little is understood about the phenotype of NP cells, including their cell-matrix interactions which may modulate phenotype and survival. Our previous work has identified strong and region-specific expression of laminins and laminin cell-surface receptors in immature NP tissues, suggesting laminin cell-matrix interactions are uniquely important to the biology of NP cells. Whether these observed tissue-level laminin expression patterns reflect functional adhesion behaviors for these cells is not known. In this study, we examined NP cell-matrix interactions with specific matrix ligands, including various laminin isoforms, using quantitative assays of cell attachment, spreading, and adhesion strength. NP cells were found to attach in higher numbers and exhibited rapid cell spreading and higher resistance to detachment force on two laminin isoforms (LM-511,LM-332) identified to be uniquely expressed in the NP region, as compared to another laminin isoform (LM-111) and several other matrix ligands (collagen, fibronectin). Additionally, NP cells were found to attach in higher numbers to laminins as compared to cells isolated from the disc's annulus fibrosus region. These findings confirm that laminin and laminin receptor expression documented in NP tissues translates into unique functional NP cell adhesion behaviors that may be useful tools for in vitro cell culture and biomaterials that support NP cells.

  10. Nucleus pulposus cell-matrix interactions with laminins

    Directory of Open Access Journals (Sweden)

    CL Gilchrist

    2011-06-01

    Full Text Available The cells of the nucleus pulposus (NP region of the intervertebral disc play a critical role in this tissue’s generation and maintenance, and alterations in NP cell viability, metabolism, and phenotype with aging may be key contributors to progressive disc degeneration. Relatively little is understood about the phenotype of NP cells, including their cell-matrix interactions which may modulate phenotype and survival. Our previous work has identified strong and region-specific expression of laminins and laminin cell-surface receptors in immature NP tissues, suggesting laminin cell-matrix interactions are uniquely important to the biology of NP cells. Whether these observed tissue-level laminin expression patterns reflect functional adhesion behaviors for these cells is not known. In this study, we examined NP cell-matrix interactions with specific matrix ligands, including various laminin isoforms, using quantitative assays of cell attachment, spreading, and adhesion strength. NP cells were found to attach in higher numbers and exhibited rapid cell spreading and higher resistance to detachment force on two laminin isoforms (LM-511,LM-332 identified to be uniquely expressed in the NP region, as compared to another laminin isoform (LM-111 and several other matrix ligands (collagen, fibronectin. Additionally, NP cells were found to attach in higher numbers to laminins as compared to cells isolated from the disc’s annulus fibrosus region. These findings confirm that laminin and laminin receptor expression documented in NP tissues translates into unique functional NP cell adhesion behaviors that may be useful tools for in vitro cell culture and biomaterials that support NP cells.

  11. Balanced transcription of cell division genes in Bacillus subtilis as revealed by single cell analysis

    NARCIS (Netherlands)

    Trip, Erik Nico; Veening, Jan-Willem; Stewart, Eric J.; Errington, Jeff; Scheffers, Dirk-Jan

    2013-01-01

    Cell division in bacteria is carried out by a set of conserved proteins that all have to function at the correct place and time. A cell cycle-dependent transcriptional programme drives cell division in bacteria such as Caulobacter crescentus. Whether such a programme exists in the Gram-positive mode

  12. 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.

  13. The Asymmetric Cell Division Regulators Par3, Scribble and Pins/Gpsm2 Are Not Essential for Erythroid Development or Enucleation

    Science.gov (United States)

    Wölwer, Christina B.; Gödde, Nathan; Pase, Luke B.; Elsum, Imogen A.; Lim, Krystle Y. B.; Sacirbegovic, Faruk; Walkley, Carl R.; Ellis, Sarah; Ohno, Shigeo; Matsuzaki, Fumio; Russell, Sarah M.; Humbert, Patrick O.

    2017-01-01

    Erythroid enucleation is the process by which the future red blood cell disposes of its nucleus prior to entering the blood stream. This key event during red blood cell development has been likened to an asymmetric cell division (ACD), by which the enucleating erythroblast divides into two very different daughter cells of alternate molecular composition, a nucleated cell that will be removed by associated macrophages, and the reticulocyte that will mature to the definitive erythrocyte. Here we investigated gene expression of members of the Par, Scribble and Pins/Gpsm2 asymmetric cell division complexes in erythroid cells, and functionally tested their role in erythroid enucleation in vivo and ex vivo. Despite their roles in regulating ACD in other contexts, we found that these polarity regulators are not essential for erythroid enucleation, nor for erythroid development in vivo. Together our results put into question a role for cell polarity and asymmetric cell division in erythroid enucleation. PMID:28095473

  14. 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.

  15. DNA replication defects delay cell division and disrupt cell polarity in early Caenorhabditis elegans embryos.

    Science.gov (United States)

    Encalada, S E; Martin, P R; Phillips, J B; Lyczak, R; Hamill, D R; Swan, K A; Bowerman, B

    2000-12-15

    In early Caenorhabditis elegans embryos, asymmetric cell divisions produce descendants with asynchronous cell cycle times. To investigate the relationship between cell cycle regulation and pattern formation, we have identified a collection of embryonic-lethal mutants in which cell divisions are delayed and cell fate patterns are abnormal. In div (for division delayed) mutant embryos, embryonic cell divisions are delayed but remain asynchronous. Some div mutants produce well-differentiated cell types, but they frequently lack the endodermal and mesodermal cell fates normally specified by a transcriptional activator called SKN-1. We show that mislocalization of PIE-1, a negative regulator of SKN-1, prevents the specification of endoderm and mesoderm in div-1 mutant embryos. In addition to defects in the normally asymmetric distribution of PIE-1, div mutants also exhibit other losses of asymmetry during early embryonic cleavages. The daughters of normally asymmetric divisions are nearly equal in size, and cytoplasmic P-granules are not properly localized to germline precursors in div mutant embryos. Thus the proper timing of cell division appears to be important for multiple aspects of asymmetric cell division. One div gene, div-1, encodes the B subunit of the DNA polymerase alpha-primase complex. Reducing the function of other DNA replication genes also results in a delayed division phenotype and embryonic lethality. Thus the other div genes we have identified are likely to encode additional components of the DNA replication machinery in C. elegans.

  16. Bacterial cell division as a target for new antibiotics.

    Science.gov (United States)

    Sass, Peter; Brötz-Oesterhelt, Heike

    2013-10-01

    Bacterial resistance to currently applied antibiotics complicates the treatment of infections and demands the evaluation of new strategies to counteract multidrug-resistant bacteria. In recent years, the inhibition of the bacterial divisome, mainly by targeting the central cell division mediator FtsZ, has been recognized as a promising strategy for antibiotic attack. New antibiotics were shown to either interfere with the natural dynamics and functions of FtsZ during the cell cycle or to activate a bacterial protease to degrade FtsZ and thus bring about bacterial death in a suicidal manner. Their efficacy in animal models of infection together with resistance-breaking properties prove the potential of such drugs and validate the inhibition of bacterial cell division as an attractive approach for antibiotic intervention.

  17. Role of polarized cell divisions in zebrafish neural tube formation.

    Science.gov (United States)

    Clarke, Jon

    2009-04-01

    Development of epithelial cell polarity and morphogenesis of a central lumen are essential prerequisites for the formation of the vertebrate neural tube. In teleost fish embryos this first involves the formation of a solid neural rod structure that then undergoes a process of cavitation to form a lumen. This process is initiated from a neural plate that has a distinct organization compared to other vertebrates, and involves complex cell intercalations and rearrangements. A key element is a mode of polarized cell division that generates daughters with mirror-image apico-basal polarity. These mirror-symmetric divisions have powerful morphogenetic influence because when they occur in ectopic locations they orchestrate the development of ectopic apical and basal specializations and the development of ectopic neural tubes.

  18. 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.

  19. Microtubules contribute to maintain nucleus shape in epithelial cell monolayer

    Science.gov (United States)

    Tremblay, Dominique; Andrzejewski, Lukasz; Pelling, Andrew

    2013-03-01

    INTRODUCTION: Tissue strains can result in significant nuclear deformations and may regulate gene expression. However, the precise role of the cytoskeleton in regulating nuclear mechanics remains poorly understood. Here, we investigate the nuclear deformability of Madin-Darky canine kidney cells (MDCK) under various stretching conditions to clarify the role of the microtubules and actin network on the mechanical behavior of the nucleus. METHODS: A custom-built cell-stretching device allowing for real time imaging of MDCK nuclei was used. Cells were seeded on a silicone membrane coated with rat-tail collagen I. A nuclear stain, Hoechst-33342, was used to image nuclei during stretching. We exposed cells to a compressive and non-compressive stretching strain field of 25%. Nocodazole and cytochalasin-D were used to depolymerize the microtubules and actin network. RESULTS: Nuclei in control cells stretched more along their minor axis than major axis with a deformation of 5% and 2% respectively. This anisotropy vanished completely in microtubule-deprived cells and these cells showed a very high nuclear deformability along the minor axis when exposed to a compressive stretching strain field. CONCLUSIONS: The microtubules drive the anisotropic deformability of MDCK nuclei in a monolayer and maintain nuclear shape when exposed to compressive strain. Such intrinsic mechanical behavior indicates that microtubules are essential to maintain nuclear shape and may prevent down regulation of gene expression.

  20. Superficial stellate cells of the dorsal cochlear nucleus

    Directory of Open Access Journals (Sweden)

    Pierre F. Apostolides

    2014-06-01

    Full Text Available The dorsal cochlear nucleus (DCN integrates auditory and multisensory signals at the earliest levels of auditory processing. Proposed roles for this region include sound localization in the vertical plane, head orientation to sounds of interest, and suppression of sensitivity to expected sounds. Auditory and non-auditory information streams to the DCN are refined by a remarkably complex array of inhibitory and excitatory interneurons, and the role of each cell type is gaining increasing attention. One inhibitory neuron that has been poorly appreciated to date is the superficial stellate cell. Here we review previous studies and describe new results that reveal the surprisingly rich interactions that this tiny interneuron has with its neighbors, interactions which enable it to respond to both multisensory and auditory afferents.

  1. Using Live-Cell Markers in Maize to Analyze Cell Division Orientation and Timing.

    Science.gov (United States)

    Rasmussen, Carolyn G

    2016-01-01

    Recently developed live-cell markers provide an opportunity to explore the dynamics and localization of proteins in maize, an important crop and model for monocot development. A step-by-step method is outlined for observing and analyzing the process of division in maize cells. The steps include plant growth conditions, sample preparation, time-lapse setup, and calculation of division rates.

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

    Directory of Open Access Journals (Sweden)

    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.

  3. Stem cell divisions, somatic mutations, cancer etiology, and cancer prevention.

    Science.gov (United States)

    Tomasetti, Cristian; Li, Lu; Vogelstein, Bert

    2017-03-24

    Cancers are caused by mutations that may be inherited, induced by environmental factors, or result from DNA replication errors (R). We studied the relationship between the number of normal stem cell divisions and the risk of 17 cancer types in 69 countries throughout the world. The data revealed a strong correlation (median = 0.80) between cancer incidence and normal stem cell divisions in all countries, regardless of their environment. The major role of R mutations in cancer etiology was supported by an independent approach, based solely on cancer genome sequencing and epidemiological data, which suggested that R mutations are responsible for two-thirds of the mutations in human cancers. All of these results are consistent with epidemiological estimates of the fraction of cancers that can be prevented by changes in the environment. Moreover, they accentuate the importance of early detection and intervention to reduce deaths from the many cancers arising from unavoidable R mutations.

  4. 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.

  5. FTSZ AND THE DIVISION OF PROKARYOTIC CELLS AND ORGANELLES

    OpenAIRE

    Margolin, William

    2005-01-01

    Binary fission of many prokaryotes as well as some eukaryotic organelles depends on the FtsZ protein, which self-assembles into a membrane-associated ring structure early in the division process. FtsZ is homologous to tubulin, the building block of the microtubule cytoskeleton in eukaryotes. Recent advances in genomics and cell-imaging techniques have paved the way for the remarkable progress in our understanding of fission in bacteria and organelles.

  6. The Stimulatory Effect of Notochordal Cell-Conditioned Medium in a Nucleus Pulposus Explant Culture

    NARCIS (Netherlands)

    de Vries, Stefan A H; van Doeselaar, Marina; Meij, Björn P; Tryfonidou, Marianna A; Ito, K

    2016-01-01

    Objectives: Notochordal cell-conditioned medium (NCCM) has previously shown to have a stimulatory effect on nucleus pulposus cells (NPCs) and bone marrow stromal cells (BMSCs) in alginate and pellet cultures. These culture methods provide a different environment than the nucleus pulposus (NP) tissue

  7. The Stimulatory Effect of Notochordal-Cell Conditioned Medium in a Nucleus Pulposus Explant Culture

    NARCIS (Netherlands)

    de Vries, Stefan; Doeselaar, Marina van; Meij, Björn; Tryfonidou, M; Ito, Keita

    2015-01-01

    OBJECTIVES: Notochordal cell-conditioned medium (NCCM) has previously shown to have a stimulatory effect on nucleus pulposus cells (NPCs) and bone marrow stromal cells (BMSCs) in alginate and pellet cultures. These culture methods provide a different environment than the nucleus pulposus (NP) tissue

  8. Sara endosomes and the asymmetric division of intestinal stem cells.

    Science.gov (United States)

    Montagne, Chrystelle; Gonzalez-Gaitan, Marcos

    2014-05-01

    Tissue homeostasis is maintained by adult stem cells, which self-renew and give rise to differentiating cells. The generation of daughter cells with different fates is mediated by signalling molecules coming from an external niche or being asymmetrically dispatched between the two daughters upon stem cell mitosis. In the adult Drosophila midgut, the intestinal stem cell (ISC) divides to generate a new ISC and an enteroblast (EB) differentiating daughter. Notch signalling activity restricted to the EB regulates intestinal cell fate decision. Here, we show that ISCs divide asymmetrically, and Sara endosomes in ISCs are specifically dispatched to the presumptive EB. During ISC mitosis, Notch and Delta traffic through Sara endosomes, thereby contributing to Notch signalling bias, as revealed in Sara mutants: Sara itself contributes to the control of the ISC asymmetric division. Our data uncover an intrinsic endosomal mechanism during ISC mitosis, which participates in the maintenance of the adult intestinal lineage.

  9. Dissection of Cell Division Processes in the One Cell Stage Caenorhabditis elegans Embryo by Mutational Analysis

    OpenAIRE

    Gönczy, Pierre; Schnabel, Heinke; Kaletta, Titus; Amores, Ana Duran; Hyman, Tony; Schnabel, Ralf

    1999-01-01

    To identify novel components required for cell division processes in complex eukaryotes, we have undertaken an extensive mutational analysis in the one cell stage Caenorhabditis elegans embryo. The large size and optical properties of this cell permit observation of cell division processes with great detail in live specimens by simple differential interference contrast (DIC) microscopy. We have screened an extensive collection of maternal-effect embryonic lethal mutations on chromosome III wi...

  10. A dynamic model of tomato fruit growth integrating cell division, cell growth and endoreduplication

    NARCIS (Netherlands)

    Fanwoua, J.; Visser, de P.H.B.; Heuvelink, E.; Yin, X.; Struik, P.C.; Marcelis, L.F.M.

    2013-01-01

    In this study, we developed a model of tomato (Solanum lycopersicum L.) fruit growth integrating cell division, cell growth and endoreduplication. The fruit was considered as a population of cells grouped in cell classes differing in their initial cell age and cell mass. The model describes fruit gr

  11. Replicating vesicles as models of primitive cell growth and division.

    Science.gov (United States)

    Hanczyc, Martin M; Szostak, Jack W

    2004-12-01

    Primitive cells, lacking the complex bio-machinery present in modern cells, would have had to rely on the self-organizing properties of their components and on interactions with their environment to achieve basic cellular functions such as growth and division. Many bilayer-membrane vesicles, depending on their composition and environment, can exhibit complex morphological changes such as growth, fusion, fission, budding, internal vesicle assembly and vesicle-surface interactions. The rich dynamic properties of these vesicles provide interesting models of how primitive cellular replication might have occurred in response to purely physical and chemical forces.

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

    Directory of Open Access Journals (Sweden)

    Cavalier-Smith Thomas

    2010-02-01

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

  13. Oriented cell division: new roles in guiding skin wound repair and regeneration.

    Science.gov (United States)

    Yang, Shaowei; Ma, Kui; Geng, Zhijun; Sun, Xiaoyan; Fu, Xiaobing

    2015-11-18

    Tissue morphogenesis depends on precise regulation and timely co-ordination of cell division and also on the control of the direction of cell division. Establishment of polarity division axis, correct alignment of the mitotic spindle, segregation of fate determinants equally or unequally between daughter cells, are essential for the realization of oriented cell division. Furthermore, oriented cell division is regulated by intrinsic cues, extrinsic cues and other cues, such as cell geometry and polarity. However, dysregulation of cell division orientation could lead to abnormal tissue development and function. In the present study, we review recent studies on the molecular mechanism of cell division orientation and explain their new roles in skin repair and regeneration.

  14. Desipramine and citalopram attenuate pretest swim-induced increases in prodynorphin immunoreactivity in the dorsal bed nucleus of the stria terminalis and the lateral division of the central nucleus of the amygdala in the forced swimming test.

    Science.gov (United States)

    Chung, Sung; Kim, Hee Jeong; Kim, Hyun Ju; Choi, Sun Hye; Cho, Jin Hee; Cho, Yun Ha; Kim, Dong-Hoon; Shin, Kyung Ho

    2014-10-01

    Dynorphin in the nucleus accumbens shell plays an important role in antidepressant-like effect in the forced swimming test (FST), but it is unclear whether desipramine and citalopram treatments alter prodynorphin levels in other brain areas. To explore this possibility, we injected mice with desipramine and citalopram 0.5, 19, and 23 h after a 15-min pretest swim and observed changes in prodynorphin expression before the test swim, which was conducted 24 h after the pretest swim. The pretest swim increased prodynorphin immunoreactivity in the dorsal bed nucleus of the stria terminalis (dBNST) and lateral division of the central nucleus of the amygdala (CeL). This increase in prodynorphin immunoreactivity in the dBNST and CeL was blocked by desipramine and citalopram treatments. Similar changes in prodynorphin mRNA levels were observed in the dBNST and CeL, but these changes did not reach significance. To understand the underlying mechanism, we assessed changes in phosphorylated CREB at Ser(133) (pCREB) immunoreactivity in the dBNST and central nucleus of the amygdala (CeA). Treatment with citalopram but not desipramine after the pretest swim significantly increased pCREB immunoreactivity only in the dBNST. These results suggest that regulation of prodynorphin in the dBNST and CeL before the test swim may be involved in the antidepressant-like effect of desipramine and citalopram in the FST and suggest that changes in pCREB immunoreactivity in these areas may not play an important role in the regulation of prodynorphin in the dBNST and CeA.

  15. Differentiation of adipose stem cells by nucleus pulposus cells: Configuration effect

    NARCIS (Netherlands)

    Lu, Z.F.; Zandieh Doulabi, B.; Wuisman, P.I.; Bank, R.A.; Helder, M.N.

    2007-01-01

    Degenerative disc disease (DDD) is a major cause of chronic low back pain. For mild/intermediate DDD, regeneration by injecting adipose stem cells (ASCs) into the nucleus pulposus (NP) may be considered. The goal of this study is to investigate whether NP cells can direct ASCs towards the NP phenoty

  16. Distribution of CD133 reveals glioma stem cells self-renew through symmetric and asymmetric cell divisions.

    Science.gov (United States)

    Lathia, J D; Hitomi, M; Gallagher, J; Gadani, S P; Adkins, J; Vasanji, A; Liu, L; Eyler, C E; Heddleston, J M; Wu, Q; Minhas, S; Soeda, A; Hoeppner, D J; Ravin, R; McKay, R D G; McLendon, R E; Corbeil, D; Chenn, A; Hjelmeland, A B; Park, D M; Rich, J N

    2011-09-01

    Malignant gliomas contain a population of self-renewing tumorigenic stem-like cells; however, it remains unclear how these glioma stem cells (GSCs) self-renew or generate cellular diversity at the single-cell level. Asymmetric cell division is a proposed mechanism to maintain cancer stem cells, yet the modes of cell division that GSCs utilize remain undetermined. Here, we used single-cell analyses to evaluate the cell division behavior of GSCs. Lineage-tracing analysis revealed that the majority of GSCs were generated through expansive symmetric cell division and not through asymmetric cell division. The majority of differentiated progeny was generated through symmetric pro-commitment divisions under expansion conditions and in the absence of growth factors, occurred mainly through asymmetric cell divisions. Mitotic pair analysis detected asymmetric CD133 segregation and not any other GSC marker in a fraction of mitoses, some of which were associated with Numb asymmetry. Under growth factor withdrawal conditions, the proportion of asymmetric CD133 divisions increased, congruent with the increase in asymmetric cell divisions observed in the lineage-tracing studies. Using single-cell-based observation, we provide definitive evidence that GSCs are capable of different modes of cell division and that the generation of cellular diversity occurs mainly through symmetric cell division, not through asymmetric cell division.

  17. Spatial and dynamic organization of molecular structures in the cell nucleus

    NARCIS (Netherlands)

    Brouwer, Anne-Kee

    2010-01-01

    In this thesis we attempt to provide a better understanding of the principles that underlie the spatial dynamic organization of the cell nucleus. Chapter 1 reviews the current status of knowledge about the structural and functional organization of the cell nucleus. In chapter 2, the development of a

  18. 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.

  19. Planar cell polarity planes the inconveniences of cell division into a smooth morphogenetic process.

    Science.gov (United States)

    Nechiporuk, Tamilla; Vasioukhin, Valeri

    2006-02-01

    Cell divisions are necessary, but also very disruptive for morphogenesis. Dividing cells lose many intercellular contacts and polarized features. This breaks the magnificent topology of the developing embryo and, if left unrepaired, can lead to severe tissue disorganization. A recent study demonstrated that cells use the planar cell polarity pathway to reestablish polarity and reintegrate daughter cells into developing tissue.

  20. Bacterial actin and tubulin homologs in cell growth and division.

    Science.gov (United States)

    Busiek, Kimberly K; Margolin, William

    2015-03-16

    In contrast to the elaborate cytoskeletal machines harbored by eukaryotic cells, such as mitotic spindles, cytoskeletal structures detectable by typical negative stain electron microscopy are generally absent from bacterial cells. As a result, for decades it was thought that bacteria lacked cytoskeletal machines. Revolutions in genomics and fluorescence microscopy have confirmed the existence not only of smaller-scale cytoskeletal structures in bacteria, but also of widespread functional homologs of eukaryotic cytoskeletal proteins. The presence of actin, tubulin, and intermediate filament homologs in these relatively simple cells suggests that primitive cytoskeletons first arose in bacteria. In bacteria such as Escherichia coli, homologs of tubulin and actin directly interact with each other and are crucial for coordinating cell growth and division. The function and direct interactions between these proteins will be the focus of this review.

  1. Heterogeneity in mitochondrial morphology and membrane potential is independent of the nuclear division cycle in multinucleate fungal cells.

    Science.gov (United States)

    Gerstenberger, John P; Occhipinti, Patricia; Gladfelter, Amy S

    2012-03-01

    In the multinucleate filamentous fungus Ashbya gossypii, nuclei divide asynchronously in a common cytoplasm. We hypothesize that the division cycle machinery has a limited zone of influence in the cytoplasm to promote nuclear autonomy. Mitochondria in cultured mammalian cells undergo cell cycle-specific changes in morphology and membrane potential and therefore can serve as a reporter of the cell cycle state of the cytoplasm. To evaluate if the cell cycle state of nuclei in A. gossypii can influence the adjacent cytoplasm, we tested whether local mitochondrial morphology and membrane potential in A. gossypii are associated with the division state of a nearby nucleus. We found that mitochondria exhibit substantial heterogeneity in both morphology and membrane potential within a single multinucleated cell. Notably, differences in mitochondrial morphology or potential are not associated with a specific nuclear division state. Heterokaryon mutants with a mixture of nuclei with deletions of and wild type for the mitochondrial fusion/fission genes DNM1 and FZO1 exhibit altered mitochondrial morphology and severe growth and sporulation defects. This dominant effect suggests that the gene products may be required locally near their expression site rather than diffusing widely in the cell. Our results demonstrate that mitochondrial dynamics are essential in these large syncytial cells, yet morphology and membrane potential are independent of nuclear cycle state.

  2. Connecting the dots of the bacterial cell cycle: Coordinating chromosome replication and segregation with cell division.

    Science.gov (United States)

    Hajduk, Isabella V; Rodrigues, Christopher D A; Harry, Elizabeth J

    2016-05-01

    Proper division site selection is crucial for the survival of all organisms. What still eludes us is how bacteria position their division site with high precision, and in tight coordination with chromosome replication and segregation. Until recently, the general belief, at least in the model organisms Bacillus subtilis and Escherichia coli, was that spatial regulation of division comes about by the combined negative regulatory mechanisms of the Min system and nucleoid occlusion. However, as we review here, these two systems cannot be solely responsible for division site selection and we highlight additional regulatory mechanisms that are at play. In this review, we put forward evidence of how chromosome replication and segregation may have direct links with cell division in these bacteria and the benefit of recent advances in chromosome conformation capture techniques in providing important information about how these three processes mechanistically work together to achieve accurate generation of progenitor cells.

  3. Common mechanisms regulating cell cortex properties during cell division and cell migration.

    Science.gov (United States)

    Roubinet, Chantal; Tran, Phong T; Piel, Matthieu

    2012-11-01

    Single cell morphogenesis results from a balance of forces involving internal pressure (also called turgor pressure in plants and fungi) and the plastic and dynamic outer shell of the cell. Dominated by the cell wall in plants and fungi, mechanical properties of the outer shell of animal cells arise from the cell cortex, which is mostly composed of the plasma membrane (and membrane proteins) and the underlying meshwork of actin filaments and myosin motors (and associated proteins). In this review, following Bray and White [1988; Science 239:883-889], we draw a parallel between the regulation of the cell cortex during cell division and cell migration in animal cells. Starting from the similarities in shape changes and underlying mechanical properties, we further propose that the analogy between cell division and cell migration might run deeper, down to the basic molecular mechanisms driving cell cortex remodeling. We focus our attention on how an heterogeneous and dynamic cortex can be generated to allow cell shape changes while preserving cell integrity.

  4. 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.

  5. AN ULTRASTRUCTURAL STUDY OF VEGETATIVE CELL DIVISION IN OEDOGONIUM BORISIANUM(1) (2).

    Science.gov (United States)

    Hill, G J; Machlis, L

    1968-12-01

    Vegetative cell division in Oedogonium borisianum is initiated by the formation of a 3-layered ring adjacent to the wall in the upper portion of the cell. This structure enlarges by the coalescence of vesicles. When the ring is fully developed, the parent wall splits adjacent to the ring, and the ring expands into a cylinder, which becomes the cuticle of the upper daughter cell. The lateral wall then forms between this cuticle and the plasmalemma of the cell. Concurrent with ring development and expansion, the nucleus migrates to a position in the center of the cell and karyokinesis occurs. Commencing with late telophase, evidence of transverse wall formation becomes apparent. The zone between the daughter nuclei contains a layer of microtubules in a plane parallel to the plane in which the transverse wall will develop. Subsequently a random coalescence of vesicles occurs along this plane. During the latter stages of this process, the ring expands and the plane of the transverse wall moves upward to the base of the ring cylinder. The completed transverse wall then fuses at is periphery with the newly formed lateral wall.

  6. The Cell Nucleus in Physiological and Experimentally Induced Hypometabolism

    Science.gov (United States)

    Malatesta, M.

    The main problem for manned space mission is, at present, represented by the mass penalty associated to the human presence. An efficient approach could be the induction of a hypometabolic stasis in the astronauts, thus drastically reducing the physical and psychological requirements of the crew. On the other hand, in the wild, a reduction in resource consumptions physiologi- cally occurs in certain animals which periodically enter hibernation, a hypometabolic state in which both the energy need and energy offer are kept at a minimum. During the last twelve years, we have been studying different tissues of hibernating dormice, with the aim of analyzing their features during the euthermia -hibernation-arousal cycle as well as getting insight into the mechanisms allowing adaptation to hypometabolism. We paid particular attention to the cell nucleus, as it is the site of chief metabolic functions, such as DNA replication and RNA transcription. Our observations revealed no significant modification in the basic features of cell nuclei during hibernation; however, the cell nuclei of hibernating dormice showed unusual nuclear bodies containing molecules involved in RNA pathways. Therefore, we supposed that they could represent storage/assembly sites of several factors for processing some RNA which could be slowly synthesised during hibernation and rapidly and abundantly released in early arousal in order to meet the increased metabolic needs of the cell. The nucleolus also underwent structural and molecular modifications during hibernation, maybe to continue important nucleolar functions, or, alternatively, permit a most efficient reactivation upon arousal. On the basis of the observations made in vivo , we recently tried to experimentally induce a reversible hypometabolic state in in vitro models, using cell lines derived from hibernating and non-hibernating species. By administering the synthetic opioid DADLE, we could significantly reduce both RNA transcrip- tion and

  7. Cell divisions are not essential for the direct conversion of fibroblasts into neuronal cells.

    Science.gov (United States)

    Fishman, V S; Shnayder, T A; Orishchenko, K E; Bader, M; Alenina, N; Serov, O L

    2015-01-01

    Direct lineage conversion is a promising approach for disease modeling and regenerative medicine. Cell divisions play a key role in reprogramming of somatic cells to pluripotency, however their role in direct lineage conversion is not clear. Here we used transdifferentiation of fibroblasts into neuronal cells by forced expression of defined transcription factors as a model system to study the role of cellular division in the direct conversion process. We have shown that conversion occurs in the presence of the cell cycle inhibitors aphidicolin or mimosine. Moreover, overexpression of the cell cycle activator cMyc negatively influences the process of direct conversion. Overall, our results suggest that cell divisions are not essential for the direct conversion of fibroblasts into neuronal cells.

  8. Cell nucleus - physical limitation of a quasar-galaxy association. Cell, DNA and cosmological background

    Energy Technology Data Exchange (ETDEWEB)

    Muheim, J.T. (Eidgenoessische Technische Hochschule, Zurich (Switzerland). Lab. fuer Festkoerperphysik)

    1985-03-15

    The author extends his analogy of atomic structure to cosmological structures to include the cell nucleus and DNA replication. From this the author believes that there is extraterrestrial life within 34 light years of us and that telepathy is possible within the solar system.

  9. Planar multipolar cells in the cochlear nucleus project to medial olivocochlear neurons in mouse.

    Science.gov (United States)

    Darrow, Keith N; Benson, Thane E; Brown, M Christian

    2012-05-01

    Medial olivocochlear (MOC) neurons originate in the superior olivary complex and project to the cochlea, where they act to reduce the effects of noise masking and protect the cochlea from damage. MOC neurons respond to sound via a reflex pathway; however, in this pathway the cochlear nucleus cell type that provides input to MOC neurons is not known. We investigated whether multipolar cells of the ventral cochlear nucleus have projections to MOC neurons by labeling them with injections into the dorsal cochlear nucleus. The projections of one type of labeled multipolar cell, planar neurons, were traced into the ventral nucleus of the trapezoid body, where they were observed terminating on MOC neurons (labeled in some cases by a second cochlear injection of FluoroGold). These terminations formed what appear to be excitatory synapses, i.e., containing small, round vesicles and prominent postsynaptic densities. These data suggest that cochlear nucleus planar multipolar neurons drive the MOC neuron's response to sound.

  10. Bradykinin promotes neuron-generating division of neural progenitor cells through ERK activation.

    Science.gov (United States)

    Pillat, Micheli M; Lameu, Claudiana; Trujillo, Cleber A; Glaser, Talita; Cappellari, Angélica R; Negraes, Priscilla D; Battastini, Ana M O; Schwindt, Telma T; Muotri, Alysson R; Ulrich, Henning

    2016-09-15

    During brain development, cells proliferate, migrate and differentiate in highly accurate patterns. In this context, published results indicate that bradykinin functions in neural fate determination, favoring neurogenesis and migration. However, mechanisms underlying bradykinin function are yet to be explored. Our findings indicate a previously unidentified role for bradykinin action in inducing neuron-generating division in vitro and in vivo, given that bradykinin lengthened the G1-phase of the neural progenitor cells (NPC) cycle and increased TIS21 (also known as PC3 and BTG2) expression in hippocampus from newborn mice. This role, triggered by activation of the kinin-B2 receptor, was conditioned by ERK1/2 activation. Moreover, immunohistochemistry analysis of hippocampal dentate gyrus showed that the percentage of Ki67(+) cells markedly increased in bradykinin-treated mice, and ERK1/2 inhibition affected this neurogenic response. The progress of neurogenesis depended on sustained ERK phosphorylation and resulted in ERK1/2 translocation to the nucleus in NPCs and PC12 cells, changing expression of genes such as Hes1 and Ngn2 (also known as Neurog2). In agreement with the function of ERK in integrating signaling pathways, effects of bradykinin in stimulating neurogenesis were reversed following removal of protein kinase C (PKC)-mediated sustained phosphorylation.

  11. Metabolic control of cell division in α-proteobacteria by a NAD-dependent glutamate dehydrogenase.

    Science.gov (United States)

    Beaufay, François; De Bolle, Xavier; Hallez, Régis

    2016-01-01

    Prior to initiate energy-consuming processes, such as DNA replication or cell division, cells need to evaluate their metabolic status. We have recently identified and characterized a new connection between metabolism and cell division in the α-proteobacterium Caulobacter crescentus. We showed that an NAD-dependent glutamate dehydrogenase (GdhZ) coordinates growth with cell division according to its enzymatic activity. Here we report the conserved role of GdhZ in controlling cell division in another α-proteobacterium, the facultative intracellular pathogen Brucella abortus. We also discuss the importance of amino acids as a main carbon source for α-proteobacteria.

  12. Asymmetric cell division and template DNA co-segregation in cancer stem cells

    Directory of Open Access Journals (Sweden)

    Sharon R Pine

    2014-08-01

    Full Text Available During tissue homeostasis, normal stem cells self-renew and repopulate the diverse cell types found within the tissue via a series of carefully controlled symmetric and asymmetric cell divisions. The notion that solid tumors comprise a subset of cancer stem cells with dysregulated self-renewal and excessive symmetric cell divisions has led to numerous studies aimed to elucidate the mechanisms regulating asymmetric cell division under steady-state conditions, during stem cell expansion, and in cancer. In this perspective, we focus on a type of asymmetry that can be established during asymmetric cell division, called non-random co-segregation of template DNA, which has been identified across numerous species, cell types and cancers. We discuss the role of p53 loss in maintaining self-renewal in both normal and malignant cells. We then review our current knowledge of the mechanisms underlying co-segregation of template DNA strands and the stem cell pathways associated with it in normal and cancer stem cells.

  13. Tomato fruit growth : integrating cell division, cell growth and endoreduplication by experimentation and modelling

    NARCIS (Netherlands)

    Fanwoua, J.

    2012-01-01

    Keywords: cell division, cell growth, cell endoreduplication, fruit growth, genotype, G×E interaction, model, tomato. Fruit size is a major component of fruit yield and quality of many crops. Variations in fruit size can be tremendous due to genotypic and environmental factors. The mechanisms

  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. Regulation of cell division in higher plants. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Jacobs, Thomas W.

    2000-02-29

    Research in the latter part of the grant period was divided into two parts: (1) expansion of the macromolecular tool kit for studying plant cell division; (2) experiments in which the roles played by plant cell cycle regulators were to be cast in the light of the emerging yeast and animal cell paradigm for molecular control of the mitotic cycle. The first objectives were accomplished to a very satisfactory degree. With regard to the second part of the project, we were driven to change our objectives for two reasons. First, the families of cell cycle control genes that we cloned encoded such closely related members that the prospects for success at raising distinguishing antisera against each were sufficiently dubious as to be impractical. Epitope tagging is not feasible in Pisum sativum, our experimental system, as this species is not realistically transformable. Therefore, differentiating the roles of diverse cyclins and cyclin-dependent kinases was problematic. Secondly, our procedure for generating mitotically synchronized pea root meristems for biochemical studies was far too labor intensive for the proposed experiments. We therefore shifted our objectives to identifying connections between the conserved proteins of the cell cycle engine and factors that interface it with plant physiology and development. In this, we have obtained some very exciting results.

  16. Dynamics of Tetrahymena macronuclear lamina during cell division

    Institute of Scientific and Technical Information of China (English)

    CHENBIN; ZHONGHEZHAI

    1994-01-01

    During mitosis,the nuclear lamina in higher eukaryotic cells undergoes a distinctly morphological change.It breaks down into lamin polymers or monomers at prophase.At telophase,the lamins reassemble around the condensed chromatin to form the layer of lamina.Using antiserum to mammalian lamins,we studied the dynamics of lamina during cell division in the macronuleus of Tetrahymena shanghaiensis,which divided in the way of amitosis.In contrast to those in higher animal cells,the typical perinuclear lamin distribution in the macronucleus persisted throughout the whole cell cycle.It was further found that in some synchronized cells,the lamin distribution bisplayed an unusual pattern consisting of a series of spots within the macronucleus.Using South-western hybridization,we found that the purified 66 KD lamin in Tetrahymena showed specific affinity with the telomere DNA sequence in the same species.Therefore,we propose that pattern of immunofluorescence may be due to the interaction of lamin protein with the nucleoli and the condensed chromatins in the macronucleus.

  17. Synchronization of Green Algae by Light and Dark Regimes for Cell Cycle and Cell Division Studies.

    Science.gov (United States)

    Hlavová, Monika; Vítová, Milada; Bišová, Kateřina

    2016-01-01

    A synchronous population of cells is one of the prerequisites for studying cell cycle processes such as DNA replication, nuclear and cellular division. Green algae dividing by multiple fission represent a unique single cell system enabling the preparation of highly synchronous cultures by application of a light-dark regime similar to what they experience in nature. This chapter provides detailed protocols for synchronization of different algal species by alternating light-dark cycles; all critical points are discussed extensively. Moreover, detailed information on basic analysis of cell cycle progression in such cultures is presented, including analyses of nuclear, cellular, and chloroplast divisions. Modifications of basic protocols that enable changes in cell cycle progression are also suggested so that nuclear or chloroplast divisions can be followed separately.

  18. 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.

  19. Factors affecting daughter cells' arrangement during the early bacterial divisions.

    Directory of Open Access Journals (Sweden)

    Pin-Tzu Su

    Full Text Available On agar plates, daughter cells of Escherichia coli mutually slide and align side-by-side in parallel during the first round of binary fission. This phenomenon has been previously attributed to an elastic material that restricts apparently separated bacteria from being in string. We hypothesize that the interaction between bacteria and the underneath substratum may affect the arrangement of the daughter bacteria. To test this hypothesis, bacterial division on hyaluronic acid (HA gel, as an alternative substratum, was examined. Consistent with our proposition, the HA gel differs from agar by suppressing the typical side-by-side alignments to a rare population. Examination of bacterial surface molecules that may contribute to the daughter cells' arrangement yielded an observation that, with disrupted lpp, the E. coli daughter cells increasingly formed non-typical patterns, i.e. neither sliding side-by-side in parallel nor forming elongated strings. Therefore, our results suggest strongly that the early cell patterning is affected by multiple interaction factors. With oscillatory optical tweezers, we further demonstrated that the interaction force decreased in bacteria without Lpp, a result substantiating our notion that the side-by-side sliding phenomenon directly reflects the strength of in-situ interaction between bacteria and substratum.

  20. Cell division plane orientation based on tensile stress in Arabidopsis thaliana.

    Science.gov (United States)

    Louveaux, Marion; Julien, Jean-Daniel; Mirabet, Vincent; Boudaoud, Arezki; Hamant, Olivier

    2016-07-26

    Cell geometry has long been proposed to play a key role in the orientation of symmetric cell division planes. In particular, the recently proposed Besson-Dumais rule generalizes Errera's rule and predicts that cells divide along one of the local minima of plane area. However, this rule has been tested only on tissues with rather local spherical shape and homogeneous growth. Here, we tested the application of the Besson-Dumais rule to the divisions occurring in the Arabidopsis shoot apex, which contains domains with anisotropic curvature and differential growth. We found that the Besson-Dumais rule works well in the central part of the apex, but fails to account for cell division planes in the saddle-shaped boundary region. Because curvature anisotropy and differential growth prescribe directional tensile stress in that region, we tested the putative contribution of anisotropic stress fields to cell division plane orientation at the shoot apex. To do so, we compared two division rules: geometrical (new plane along the shortest path) and mechanical (new plane along maximal tension). The mechanical division rule reproduced the enrichment of long planes observed in the boundary region. Experimental perturbation of mechanical stress pattern further supported a contribution of anisotropic tensile stress in division plane orientation. Importantly, simulations of tissues growing in an isotropic stress field, and dividing along maximal tension, provided division plane distributions comparable to those obtained with the geometrical rule. We thus propose that division plane orientation by tensile stress offers a general rule for symmetric cell division in plants.

  1. Novel insights into mammalian embryonic neural stem cell division: focus on microtubules.

    Science.gov (United States)

    Mora-Bermúdez, Felipe; Huttner, Wieland B

    2015-12-01

    During stem cell divisions, mitotic microtubules do more than just segregate the chromosomes. They also determine whether a cell divides virtually symmetrically or asymmetrically by establishing spindle orientation and the plane of cell division. This can be decisive for the fate of the stem cell progeny. Spindle defects have been linked to neurodevelopmental disorders, yet the role of spindle orientation for mammalian neurogenesis has remained controversial. Here we explore recent advances in understanding how the microtubule cytoskeleton influences mammalian neural stem cell division. Our focus is primarily on the role of spindle microtubules in the development of the cerebral cortex. We also highlight unique characteristics in the architecture and dynamics of cortical stem cells that are tightly linked to their mode of division. These features contribute to setting these cells apart as mitotic "rule breakers," control how asymmetric a division is, and, we argue, are sufficient to determine the fate of the neural stem cell progeny in mammals.

  2. 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.

  3. Shuttling of the autoantigen La between nucleus and cell surface after uv irradiation of human keratinocytes

    Energy Technology Data Exchange (ETDEWEB)

    Bachmann, M.; Chang, S.; Slor, H.; Kukulies, J.; Mueller, W.E. (Universitaet, Mainz (Germany, F.R.))

    1990-12-01

    During the past years we have established that the nuclear autoantigen La shuttles between the nucleus and the cytoplasm in tumor cells after inhibition of transcription or virus infection. We reinvestigated this shuttling using primary human keratinocytes from both healthy donors and patients with xeroderma pigmentosum. Ultraviolet irradiation resulted in both an inhibition of transcription and a translocation of La protein from the nucleus to the cytoplasm. After a prolonged inhibition of transcription La protein relocated into the nucleus and assembled with nuclear storage regions. The uv-induced shuttling included a translocation to the cell surface, where La protein colocalized with epidermal growth factor receptors.

  4. A DNA damage-induced, SOS-independent checkpoint regulates cell division in Caulobacter crescentus.

    Directory of Open Access Journals (Sweden)

    Joshua W Modell

    2014-10-01

    Full Text Available Cells must coordinate DNA replication with cell division, especially during episodes of DNA damage. The paradigm for cell division control following DNA damage in bacteria involves the SOS response where cleavage of the transcriptional repressor LexA induces a division inhibitor. However, in Caulobacter crescentus, cells lacking the primary SOS-regulated inhibitor, sidA, can often still delay division post-damage. Here we identify didA, a second cell division inhibitor that is induced by DNA damage, but in an SOS-independent manner. Together, DidA and SidA inhibit division, such that cells lacking both inhibitors divide prematurely following DNA damage, with lethal consequences. We show that DidA does not disrupt assembly of the division machinery and instead binds the essential division protein FtsN to block cytokinesis. Intriguingly, mutations in FtsW and FtsI, which drive the synthesis of septal cell wall material, can suppress the activity of both SidA and DidA, likely by causing the FtsW/I/N complex to hyperactively initiate cell division. Finally, we identify a transcription factor, DriD, that drives the SOS-independent transcription of didA following DNA damage.

  5. A DNA damage-induced, SOS-independent checkpoint regulates cell division in Caulobacter crescentus.

    Science.gov (United States)

    Modell, Joshua W; Kambara, Tracy K; Perchuk, Barrett S; Laub, Michael T

    2014-10-01

    Cells must coordinate DNA replication with cell division, especially during episodes of DNA damage. The paradigm for cell division control following DNA damage in bacteria involves the SOS response where cleavage of the transcriptional repressor LexA induces a division inhibitor. However, in Caulobacter crescentus, cells lacking the primary SOS-regulated inhibitor, sidA, can often still delay division post-damage. Here we identify didA, a second cell division inhibitor that is induced by DNA damage, but in an SOS-independent manner. Together, DidA and SidA inhibit division, such that cells lacking both inhibitors divide prematurely following DNA damage, with lethal consequences. We show that DidA does not disrupt assembly of the division machinery and instead binds the essential division protein FtsN to block cytokinesis. Intriguingly, mutations in FtsW and FtsI, which drive the synthesis of septal cell wall material, can suppress the activity of both SidA and DidA, likely by causing the FtsW/I/N complex to hyperactively initiate cell division. Finally, we identify a transcription factor, DriD, that drives the SOS-independent transcription of didA following DNA damage.

  6. 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.

  7. Arabidopsis TCP20 links regulation of growth and cell division control pathways

    OpenAIRE

    2005-01-01

    During postembryonic plant development, cell division is coupled to cell growth. There is a stringent requirement to couple these processes in shoot and root meristems. As cells pass through meristems, they transit through zones with high rates of cell growth and proliferation during organogenesis. This transition implies a need for coordinate regulation of genes underpinning these two fundamental cell functions. Here, we report a mechanism for coregulation of cell division control genes and ...

  8. Dissection of Cell Division Processes in the One Cell Stage Caenorhabditis elegans Embryo by Mutational Analysis

    Science.gov (United States)

    Gönczy, Pierre; Schnabel, Heinke; Kaletta, Titus; Amores, Ana Duran; Hyman, Tony; Schnabel, Ralf

    1999-01-01

    To identify novel components required for cell division processes in complex eukaryotes, we have undertaken an extensive mutational analysis in the one cell stage Caenorhabditis elegans embryo. The large size and optical properties of this cell permit observation of cell division processes with great detail in live specimens by simple differential interference contrast (DIC) microscopy. We have screened an extensive collection of maternal-effect embryonic lethal mutations on chromosome III with time-lapse DIC video microscopy. Using this assay, we have identified 48 mutations in 34 loci which are required for specific cell division processes in the one cell stage embryo. We show that mutations fall into distinct phenotypic classes which correspond, among others, to the processes of pronuclear migration, rotation of centrosomes and associated pronuclei, spindle assembly, chromosome segregation, anaphase spindle positioning, and cytokinesis. We have further analyzed pronuclear migration mutants by indirect immunofluorescence microscopy using antibodies against tubulin and ZYG-9, a centrosomal marker. This analysis revealed that two pronuclear migration loci are required for generating normal microtubule arrays and four for centrosome separation. All 34 loci have been mapped by deficiencies to distinct regions of chromosome III, thus paving the way for their rapid molecular characterization. Our work contributes to establishing the one cell stage C. elegans embryo as a powerful metazoan model system for dissecting cell division processes. PMID:10085292

  9. 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.

  10. 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.

  11. Splitting the cell, building the organism: Mechanisms of cell division in metazoan embryos.

    Science.gov (United States)

    Kumar, Megha; Pushpa, Kumari; Mylavarapu, Sivaram V S

    2015-07-01

    The unicellular metazoan zygote undergoes a series of cell divisions that are central to its development into an embryo. Differentiation of embryonic cells leads eventually to the development of a functional adult. Fate specification of pluripotent embryonic cells occurs during the early embryonic cleavage divisions in several animals. Early development is characterized by well-known stages of embryogenesis documented across animals--morulation, blastulation, and morphogenetic processes such as gastrulation, all of which contribute to differentiation and tissue specification. Despite this broad conservation, there exist clearly discernible morphological and functional differences across early embryonic stages in metazoans. Variations in the mitotic mechanisms of early embryonic cell divisions play key roles in governing these gross differences that eventually encode developmental patterns. In this review, we discuss molecular mechanisms of both karyokinesis (nuclear division) and cytokinesis (cytoplasmic separation) during early embryonic divisions. We outline the broadly conserved molecular pathways that operate in these two stages in early embryonic mitoses. In addition, we highlight mechanistic variations in these two stages across different organisms. We finally discuss outstanding questions of interest, answers to which would illuminate the role of divergent mitotic mechanisms in shaping early animal embryogenesis.

  12. Cell division in Escherichia coli cultures monitored at single cell resolution

    Directory of Open Access Journals (Sweden)

    Luidalepp Hannes

    2008-04-01

    Full Text Available Abstract Background A fundamental characteristic of cells is the ability to divide. To date, most parameters of bacterial cultures, including cell division, have been measured as cell population averages, assuming that all bacteria divide at a uniform rate. Results We monitored the division of individual cells in Escherichia coli cultures during different growth phases. Our experiments are based on the dilution of green fluorescent protein (GFP upon cell division, monitored by flow cytometry. The results show that the vast majority of E. coli cells in exponentially growing cultures divided uniformly. In cultures that had been in stationary phase up to four days, no cell division was observed. However, upon dilution of stationary phase culture into fresh medium, two subpopulations of cells emerged: one that started dividing and another that did not. These populations were detectable by GFP dilution and displayed different side scatter parameters in flow cytometry. Further analysis showed that bacteria in the non-growing subpopulation were not dead, neither was the difference in growth capacity reducible to differences in stationary phase-specific gene expression since we observed uniform expression of several stress-related promoters. The presence of non-growing persisters, temporarily dormant bacteria that are tolerant to antibiotics, has previously been described within growing bacterial populations. Using the GFP dilution method combined with cell sorting, we showed that ampicillin lyses growing bacteria while non-growing bacteria retain viability and that some of them restart growth after the ampicillin is removed. Thus, our method enables persisters to be monitored even in liquid cultures of wild type strains in which persister formation has low frequency. Conclusion In principle, the approaches developed here could be used to detect differences in cell division in response to different environmental conditions and in cultures of unicellular

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

    Science.gov (United States)

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

    2006-04-21

    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.

  14. Segrosome complex formation during DNA trafficking in bacterial cell division

    Directory of Open Access Journals (Sweden)

    Maria A. Oliva

    2016-09-01

    Full Text Available Bacterial extrachromosomal DNAs often contribute to virulence in pathogenic organisms or facilitate adaptation to particular environments. The transmission of genetic information from one generation to the next requires sufficient partitioning of DNA molecules to ensure that at least one copy reaches each side of the division plane and is inherited by the daughter cells. Segregation of the bacterial chromosome occurs during or after replication and probably involves a strategy in which several protein complexes participate to modify the folding pattern and distribution first of the origin domain and then of the rest of the chromosome. Low-copy number plasmids rely on specialised partitioning systems, which in some cases use a mechanism that show striking similarity to eukaryotic DNA segregation. Overall, there have been multiple systems implicated in the dynamic transport of DNA cargo to a new cellular position during the cell cycle but most seem to share a common initial DNA partitioning step, involving the formation of a nucleoprotein complex called the segrosome. The particular features and complex topologies of individual segrosomes depend on both the nature of the DNA binding protein involved and on the recognized centromeric DNA sequence, both of which vary across systems. The combination of in vivo and in vitro approaches, with structural biology has significantly furthered our understanding of the mechanisms underlying DNA trafficking in bacteria. Here, I discuss recent advances and the molecular details of the DNA segregation machinery, focusing on the formation of the segrosome complex.

  15. Probabilistic model of microbial cell growth, division, and mortality.

    Science.gov (United States)

    Horowitz, Joseph; Normand, Mark D; Corradini, Maria G; Peleg, Micha

    2010-01-01

    After a short time interval of length deltat during microbial growth, an individual cell can be found to be divided with probability Pd(t)deltat, dead with probability Pm(t)deltat, or alive but undivided with the probability 1-[Pd(t)+Pm(t)]deltat, where t is time, Pd(t) expresses the probability of division for an individual cell per unit of time, and Pm(t) expresses the probability of mortality per unit of time. These probabilities may change with the state of the population and the habitat's properties and are therefore functions of time. This scenario translates into a model that is presented in stochastic and deterministic versions. The first, a stochastic process model, monitors the fates of individual cells and determines cell numbers. It is particularly suitable for small populations such as those that may exist in the case of casual contamination of a food by a pathogen. The second, which can be regarded as a large-population limit of the stochastic model, is a continuous mathematical expression that describes the population's size as a function of time. It is suitable for large microbial populations such as those present in unprocessed foods. Exponential or logistic growth with or without lag, inactivation with or without a "shoulder," and transitions between growth and inactivation are all manifestations of the underlying probability structure of the model. With temperature-dependent parameters, the model can be used to simulate nonisothermal growth and inactivation patterns. The same concept applies to other factors that promote or inhibit microorganisms, such as pH and the presence of antimicrobials, etc. With Pd(t) and Pm(t) in the form of logistic functions, the model can simulate all commonly observed growth/mortality patterns. Estimates of the changing probability parameters can be obtained with both the stochastic and deterministic versions of the model, as demonstrated with simulated data.

  16. In situ label-free cell viability assessment of nucleus pulposus tissue.

    Science.gov (United States)

    Dittmar, Roman; van Dijk, Bart G M; van Zandvoort, Marc A M J; Ito, Keita

    2014-04-01

    Regenerative medicine approaches aiming at treating degenerating intervertebral discs, a major cause of back pain, are increasingly tested in ex-vivo disc explant models mimicking in-vivo conditions. For assessing the efficacy of regenerative therapies, cell viability is commonly measured requiring specific labels to stain cells. Here, we demonstrate and evaluate how cellular auto-fluorescence can be utilized to non-invasively assess viability in disc tissue in-situ using label-free two-photon microscopy. Live and dead bovine disc cells (0% and 100% cell viability) from the nucleus pulposus were seeded into collagen gels and auto-fluorescence was characterized. Subsequently, nucleus pulposus explants were cultured for 6 days in media with different glucose supplementation (0, 0.25, 0.5, and 1 g/L) to induce different degrees of cell death. Then, samples were split and viability was assessed using label-free two-photon microscopy and conventional staining. Results show that live and dead nucleus pulposus cells systematically emit auto-fluorescent light with distinct characteristics. Cell viability values obtained with label-free microscopy did not significantly differ from those acquired with staining. In summary, monitoring auto-fluorescence facilitates accurate cell viability assessment in nucleus tissue requiring no additional dyes. Thus, this technique may be suitable for pre-clinical testing of regenerative therapies in nucleus pulposus cultures. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:545-550, 2014.

  17. Plasma cell differentiation is coupled to division-dependent DNA hypomethylation and gene regulation.

    Science.gov (United States)

    Barwick, Benjamin G; Scharer, Christopher D; Bally, Alexander P R; Boss, Jeremy M

    2016-10-01

    The epigenetic processes that regulate antibody-secreting plasma cells are not well understood. Here, analysis of plasma cell differentiation revealed DNA hypomethylation of 10% of CpG loci that were overrepresented at enhancers. Inhibition of DNA methylation enhanced plasma cell commitment in a cell-division-dependent manner. Analysis of B cells differentiating in vivo stratified by cell division revealed a fivefold increase in mRNA transcription coupled to DNA hypomethylation. Demethylation occurred first at binding motifs for the transcription factors NF-κB and AP-1 and later at those for the transcription factors IRF and Oct-2 and was coincident with activation and differentiation gene-expression programs in a cell-division-dependent manner. These data provide mechanistic insight into cell-division-coupled transcriptional and epigenetic reprogramming and suggest that DNA hypomethylation reflects the cis-regulatory history of plasma cell differentiation.

  18. Droplet size influences division of mammalian cell factories in droplet microfluidic cultivation

    DEFF Research Database (Denmark)

    Periyannan Rajeswari, Prem Kumar; Joensson, Haakan N.; Svahn, Helene Andersson

    2017-01-01

    The potential of using droplet microfluidics for screening mammalian cell factories has been limited by the difficulty in achieving continuous cell division during cultivation in droplets. Here, we report the influence of droplet size on mammalian cell division and viability during cultivation......, making them a more suitable droplet size for 72-h cultivation. This study shows a direct correlation of microfluidic droplet size to the division and viability of mammalian cells. This highlights the importance of selecting suitable droplet size for mammalian cell factory screening assays....... in droplets. Chinese Hamster Ovary (CHO) cells, the most widely used mammalian host cells for biopharmaceuticals production were encapsulated and cultivated in 33, 180 and 320 pL droplets for 3 days. Periodic monitoring of the droplets during incubation showed that the cell divisions in 33 pL droplets stopped...

  19. MioC and GidA proteins promote cell division in E. coli

    Directory of Open Access Journals (Sweden)

    Mark eLies

    2015-05-01

    Full Text Available The well-conserved genes surrounding the E. coli replication origin, mioC and gidA, do not affect chromosome replication and have little known function. We report that mioC and gidA mutants exhibit a mild cell division inhibition phenotype, which is exacerbated by a fis deletion. Measurements replication initiation frequency, replication elongation, and chromosome segregation indicate that cell division inhibition does not involve any effects of these genes on oriC function. Division inhibition is independent of the major cell division control systems including the SOS response and nucleoid occlusion. Complementation analysis indicates that mioC and gidA affect cell division in trans, and transcriptome analysis by next-generation RNA sequencing showed that expression of a cell division septum component, YmgF, is strongly affected in both mioC and gidA mutants. Our results suggest that MioC and GidA proteins are involved in a cell division regulatory pathway, which may link DNA replication and division.

  20. Arabidopsis  SABRE and CLASP interact to stabilize cell division plane orientation and planar polarity

    OpenAIRE

    2013-01-01

    The orientation of cell division and the coordination of cell polarity within the plane of the tissue layer (planar polarity) contribute to shape diverse multicellular organisms. The root of Arabidopsis thaliana displays regularly oriented cell divisions, cell elongation and planar polarity providing a plant model system to study these processes. Here we report that the SABRE protein, which shares similarity with proteins of unknown function throughout eukaryotes, has important roles in orien...

  1. Three Dimensional Simulation Method in Early Process of Division and Growth for Tumour Cells

    Institute of Scientific and Technical Information of China (English)

    XIA Zhi-qiu; ZHAO Ting-ting

    2014-01-01

    The process of division, growth and death for tumour cell mass in the early is simulated. An integrated GUI is provided for users to set the value of each parameters, which are cell growth rates, cell mass division rates, cell mass death rates, simulate type, maximum running time, polarity and cell colour. It can display the growth process of each cell on result GUI. Also, it can display the values of each parameters for observing and analysing in current life cycle on result GUI, which are cell mass division times, cell mass death rate, cell mass division rate and cell mass growth rate. In the process of simulation, The cell growth rate is described by the approach to combine the exponential model with the linear model. In addition, a linked list data structure to store the tumour cells is used by the cellular automata for a reference to determine the position of each cell. It sets up two linked list to store the cells, one of them save the new small division cells and the other one save the big cell. That can make the painting process of cells on result GUI clearer and more organized. At last, the polarity of tumour growth is described for determining the growth direction of cells.

  2. Positive control of cell division: FtsZ is recruited by SsgB during sporulation of Streptomyces

    NARCIS (Netherlands)

    Willemse, J.; Borst, J.W.; Waal, de E.; Bisseling, T.; Wezel, van G.P.

    2011-01-01

    In bacteria that divide by binary fission, cell division starts with the polymerization of the tubulin homolog FtsZ at mid-cell to form a cell division scaffold (the Z ring), followed by recruitment of the other divisome components. The current view of bacterial cell division control starts from the

  3. Optimal architecture of differentiation cascades with asymmetric and symmetric stem cell division.

    Science.gov (United States)

    Sánchez-Taltavull, Daniel

    2016-10-21

    The role of symmetric division in stem cell biology is ambiguous. It is necessary after injuries, but if symmetric divisions occur too often, the appearance of tumours is more likely. To explore the role of symmetric and asymmetric division in cell populations, we propose a mathematical model of competition of populations, in which the stem cell expansion is controlled by fully differentiated cells. We show that there is an optimal fraction of symmetric stem cell division, which maximises the long-term survival probability of the organism. Moreover, we show the optimal number of stem cells in a tissue, and we show that number has to be small enough to reduce the probability of the appearance of advantageous malignant cells, and large enough to assure that the population will not be suppressed by stochastic fluctuations.

  4. A theory of germinal center B cell selection, division, and exit.

    Science.gov (United States)

    Meyer-Hermann, Michael; Mohr, Elodie; Pelletier, Nadége; Zhang, Yang; Victora, Gabriel D; Toellner, Kai-Michael

    2012-07-26

    High-affinity antibodies are generated in germinal centers in a process involving mutation and selection of B cells. Information processing in germinal center reactions has been investigated in a number of recent experiments. These have revealed cell migration patterns, asymmetric cell divisions, and cell-cell interaction characteristics, used here to develop a theory of germinal center B cell selection, division, and exit (the LEDA model). According to this model, B cells selected by T follicular helper cells on the basis of successful antigen processing always return to the dark zone for asymmetric division, and acquired antigen is inherited by one daughter cell only. Antigen-retaining B cells differentiate to plasma cells and leave the germinal center through the dark zone. This theory has implications for the functioning of germinal centers because compared to previous models, high-affinity antibodies appear one day earlier and the amount of derived plasma cells is considerably larger.

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

    Directory of Open Access Journals (Sweden)

    Tong Zhang

    Full Text Available BACKGROUND: 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. METHODOLOGY AND PRINCIPAL FINDINGS: 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. CONCLUSION AND SIGNIFICANCE: 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.

  6. Planar cell polarity signalling couples cell division and morphogenesis during neurulation.

    Science.gov (United States)

    Ciruna, Brian; Jenny, Andreas; Lee, Diana; Mlodzik, Marek; Schier, Alexander F

    2006-01-12

    Environmental and genetic aberrations lead to neural tube closure defects (NTDs) in 1 out of every 1,000 births. Mouse and frog models for these birth defects have indicated that Van Gogh-like 2 (Vangl2, also known as Strabismus) and other components of planar cell polarity (PCP) signalling might control neurulation by promoting the convergence of neural progenitors to the midline. Here we show a novel role for PCP signalling during neurulation in zebrafish. We demonstrate that non-canonical Wnt/PCP signalling polarizes neural progenitors along the anteroposterior axis. This polarity is transiently lost during cell division in the neural keel but is re-established as daughter cells reintegrate into the neuroepithelium. Loss of zebrafish Vangl2 (in trilobite mutants) abolishes the polarization of neural keel cells, disrupts re-intercalation of daughter cells into the neuroepithelium, and results in ectopic neural progenitor accumulations and NTDs. Remarkably, blocking cell division leads to rescue of trilobite neural tube morphogenesis despite persistent defects in convergence and extension. These results reveal a function for PCP signalling in coupling cell division and morphogenesis at neurulation and indicate a previously unrecognized mechanism that might underlie NTDs.

  7. Local 3D matrix confinement determines division axis through cell shape.

    Science.gov (United States)

    He, Lijuan; Chen, Weitong; Wu, Pei-Hsun; Jimenez, Angela; Wong, Bin Sheng; San, Angela; Konstantopoulos, Konstantinos; Wirtz, Denis

    2016-02-01

    How the division axis is determined in mammalian cells embedded in three-dimensional (3D) matrices remains elusive, despite that many types of cells divide in 3D environments. Cells on two-dimensional (2D) substrates typically round up completely to divide. Here, we show that in 3D collagen matrices, mammalian cells such as HT1080 human fibrosarcoma and MDA-MB-231 breast cancer cells exhibit division modes distinct from their Counterparts on 2D substrates, with a markedly higher fraction of cells remaining highly elongated through mitosis in 3D matrices. The long axis of elongated mitotic cells accurately predicts the division axis, independently of matrix density and cell-matrix interactions. This 3D-specific elongated division mode is determined by the local confinement produced by the matrix and the ability of cells to protrude and locally remodel the matrix via β1 integrin. Elongated division is readily recapitulated using collagen-coated microfabricated channels. Cells depleted of β1 integrin still divide in the elongated mode in microchannels, suggesting that 3D confinement is sufficient to induce the elongated cell-division phenotype.

  8. 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.

  9. CyDiv, a conserved and novel filamentous Cyanobacteria cell division protein involved in septum localization.

    Directory of Open Access Journals (Sweden)

    Dinka eMandakovic

    2016-02-01

    Full Text Available Cell division in bacteria has been studied mostly in Escherichia coli and Bacillus subtilis, model organisms for Gram-negative and Gram-positive bacteria, respectively. However, cell division in filamentous cyanobacteria is poorly understood. Here, we identified a novel protein, named CyDiv (Cyanobacterial Division, encoded by the all2320 gene in Anabaena sp. PCC 7120. We show that CyDiv plays a key role during cell division. CyDiv has been previously described only as an exclusive and conserved hypothetical protein in filamentous cyanobacteria. Using polyclonal antibodies against CyDiv, we showed that it localizes at different positions depending on cell division timing: poles, septum, in both daughter cells, but also in only one of the daughter cells. The partial deletion of CyDiv gene generates partial defects in cell division, including severe membrane instability and anomalous septum localization during late division. The inability to complete knock out CyDiv strains suggests that it is an essential gene. In silico structural protein analyses and our experimental results suggest that CyDiv is an FtsB/DivIC-like protein, and could therefore, be part of an essential late divisome complex in Anabaena sp. PCC 7120.

  10. CyDiv, a Conserved and Novel Filamentous Cyanobacterial Cell Division Protein Involved in Septum Localization

    Science.gov (United States)

    Mandakovic, Dinka; Trigo, Carla; Andrade, Derly; Riquelme, Brenda; Gómez-Lillo, Gabriela; Soto-Liebe, Katia; Díez, Beatriz; Vásquez, Mónica

    2016-01-01

    Cell division in bacteria has been studied mostly in Escherichia coli and Bacillus subtilis, model organisms for Gram-negative and Gram-positive bacteria, respectively. However, cell division in filamentous cyanobacteria is poorly understood. Here, we identified a novel protein, named CyDiv (Cyanobacterial Division), encoded by the all2320 gene in Anabaena sp. PCC 7120. We show that CyDiv plays a key role during cell division. CyDiv has been previously described only as an exclusive and conserved hypothetical protein in filamentous cyanobacteria. Using polyclonal antibodies against CyDiv, we showed that it localizes at different positions depending on cell division timing: poles, septum, in both daughter cells, but also in only one of the daughter cells. The partial deletion of CyDiv gene generates partial defects in cell division, including severe membrane instability and anomalous septum localization during late division. The inability to complete knock out CyDiv strains suggests that it is an essential gene. In silico structural protein analyses and our experimental results suggest that CyDiv is an FtsB/DivIC-like protein, and could therefore, be part of an essential late divisome complex in Anabaena sp. PCC 7120. PMID:26903973

  11. ANA detected by ELISA using nucleus of egg cell as antigen.

    Science.gov (United States)

    Hui, Liu; Shijun, Li; Yue, Ma

    2008-01-01

    Antinuclear antibodies, ANA, were usually detected with antigen of somatic cell nucleus. It has not been reported to detect ANA with egg cell nucleus as antigen. Enzyme linked immuosorbent assay, ELISA, coated with yolk was developed to detect ANA in our laboratory. A quality control test, cross absorption test, and cross antibody-induced test with yolk were performed. Results showed a good agreement between our method and IFA through measurement of the same samples from patients suspected of having rheumatic connective tissue diseases (Kappa=0.668, P=0.000). The results were not influenced by the RF and different sources of egg. CVs of inter-assay, were less than 10%. The cross absorption test was negative, as well; the ANA to somatic cell nucleus could be induced with egg cell nucleus. It is implied that there were both cross as well as overlapped Egg-ANA and Somatic-ANA. As egg nucleus, its volume was large, its purification was simple, so the better method might be established.

  12. Chromosome segregation impacts on cell growth and division site selection in Corynebacterium glutamicum.

    Science.gov (United States)

    Donovan, Catriona; Schauss, Astrid; Krämer, Reinhard; Bramkamp, Marc

    2013-01-01

    Spatial and temporal regulation of bacterial cell division is imperative for the production of viable offspring. In many rod-shaped bacteria, regulatory systems such as the Min system and nucleoid occlusion ensure the high fidelity of midcell divisome positioning. However, regulation of division site selection in bacteria lacking recognizable Min and nucleoid occlusion remains less well understood. Here, we describe one such rod-shaped organism, Corynebacterium glutamicum, which does not always place the division septum precisely at midcell. Here we now show at single cell level that cell growth and division site selection are spatially and temporally regulated by chromosome segregation. Mutants defective in chromosome segregation have more variable cell growth and aberrant placement of the division site. In these mutants, division septa constrict over and often guillotine the nucleoid, leading to nonviable, DNA-free cells. Our results suggest that chromosome segregation or some nucleoid associated factor influences growth and division site selection in C. glutamicum. Understanding growth and regulation of C. glutamicum cells will also be of importance to develop strains for industrial production of biomolecules, such as amino acids.

  13. Chromosome segregation impacts on cell growth and division site selection in Corynebacterium glutamicum.

    Directory of Open Access Journals (Sweden)

    Catriona Donovan

    Full Text Available Spatial and temporal regulation of bacterial cell division is imperative for the production of viable offspring. In many rod-shaped bacteria, regulatory systems such as the Min system and nucleoid occlusion ensure the high fidelity of midcell divisome positioning. However, regulation of division site selection in bacteria lacking recognizable Min and nucleoid occlusion remains less well understood. Here, we describe one such rod-shaped organism, Corynebacterium glutamicum, which does not always place the division septum precisely at midcell. Here we now show at single cell level that cell growth and division site selection are spatially and temporally regulated by chromosome segregation. Mutants defective in chromosome segregation have more variable cell growth and aberrant placement of the division site. In these mutants, division septa constrict over and often guillotine the nucleoid, leading to nonviable, DNA-free cells. Our results suggest that chromosome segregation or some nucleoid associated factor influences growth and division site selection in C. glutamicum. Understanding growth and regulation of C. glutamicum cells will also be of importance to develop strains for industrial production of biomolecules, such as amino acids.

  14. Asymmetric cell division of granule neuron progenitors in the external granule layer of the mouse cerebellum.

    Science.gov (United States)

    Haldipur, Parthiv; Sivaprakasam, Iswariya; Periasamy, Vinod; Govindan, Subashika; Mani, Shyamala

    2015-05-15

    The plane of division of granule neuron progenitors (GNPs) was analysed with respect to the pial surface in P0 to P14 cerebellum and the results showed that there was a significant bias towards the plane of cell division being parallel to pial surface across this developmental window. In addition, the distribution of β-Catenin in anaphase cells was analysed, which showed that there was a significant asymmetry in the distribution of β-Catenin in dividing GNPs. Further, inhibition of Sonic Hedgehog (Shh) signalling had an effect on plane of cell division. Asymmetric distribution of β-Catenin was shown to occur towards the source of a localized extracellular cue.

  15. The essential cell division protein FtsN interacts with the murein (peptidoglycan) synthase PBP1B in Escherichia coli

    NARCIS (Netherlands)

    Müller, Patrick; Ewers, C.; Bertsche, U.; Anstett, M.; Kallis, T.; Breukink, E.J.; Fraipont, Claudine; Terrak, Mohammed; Nguyen-Distèche, Martine; Vollmer, W.

    2007-01-01

    Bacterial cell division requires the coordinated action of cell division proteins and murein (peptidoglycan) synthases. Interactions involving the essential cell division protein FtsN and murein synthases were studied by affinity chromatography with membrane fraction. The murein synthases PBP1A, PBP

  16. YgbQ, a cell division protein in Escherichia coli and Vibrio cholerae, localizes in codependent fashion with FtsL to the division site

    OpenAIRE

    Buddelmeijer, Nienke; Judson, Nicholas; Boyd, Dana; Mekalanos, John J.; Beckwith, Jonathan

    2002-01-01

    YgbQ is a cell division protein in Escherichia coli and Vibrio cholerae. In E. coli the ygbQ gene was discovered as a result of a computer search of the E. coli genome designed to find potential interacting partners for cell division protein FtsL. In V. cholerae, ygbQ was identified as an essential gene by using a transposon that fuses genes to an arabinose promoter. The role of YgbQ in cell division is supported by the following. Cells depleted of YgbQ in both organisms form long filaments, ...

  17. Temperature-induced labelling of Fluo-3 AM selectively yields brighter nucleus in adherent cells

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Guixian [The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, School of Physics and TEDA Applied Physics Institute, Nankai University, Tianjin (China); Pan, Leiting, E-mail: plt@nankai.edu.cn [The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, School of Physics and TEDA Applied Physics Institute, Nankai University, Tianjin (China); Li, Cunbo; Hu, Fen; Shi, Xuechen; Lee, Imshik [The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, School of Physics and TEDA Applied Physics Institute, Nankai University, Tianjin (China); Drevenšek-Olenik, Irena [Faculty of Mathematics and Physics, University of Ljubljana, and J. Stefan Institute, Ljubljana (Slovenia); Zhang, Xinzheng; Xu, Jingjun [The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, School of Physics and TEDA Applied Physics Institute, Nankai University, Tianjin (China)

    2014-01-17

    Highlights: •We detailedly examine temperature effects of Fluo-3 AM labelling in adherent cells. •4 °C Loading and 20 °C de-esterification of Fluo-3 AM yields brighter nuclei. •Brighter nuclei labelling by Fluo-3 AM also depends on cell adhesion quality. •A qualitative model of the brighter nucleus is proposed. -- Abstract: Fluo-3 is widely used to study cell calcium. Two traditional approaches: (1) direct injection and (2) Fluo-3 acetoxymethyl ester (AM) loading, often bring conflicting results in cytoplasmic calcium ([Ca{sup 2+}]{sub c}) and nuclear calcium ([Ca{sup 2+}]{sub n}) imaging. AM loading usually yields a darker nucleus than in cytoplasm, while direct injection always induces a brighter nucleus which is more responsive to [Ca{sup 2+}]{sub n} detection. In this work, we detailedly investigated the effects of loading and de-esterification temperatures on the fluorescence intensity of Fluo-3 in response to [Ca{sup 2+}]{sub n} and [Ca{sup 2+}]{sub c} in adherent cells, including osteoblast, HeLa and BV2 cells. Interestingly, it showed that fluorescence intensity of nucleus in osteoblast cells was about two times larger than that of cytoplasm when cells were loaded with Fluo-3 AM at 4 °C and allowed a subsequent step for de-esterification at 20 °C. Brighter nuclei were also acquired in HeLa and BV2 cells using the same experimental condition. Furthermore, loading time and adhesion quality of cells had effect on fluorescence intensity. Taken together, cold loading and room temperature de-esterification treatment of Fluo-3 AM selectively yielded brighter nucleus in adherent 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. Ultrastructure and immunocytochemical characteristics of cells in the octopus cell area of the rat cochlear nucleus: comparison with multipolar cells.

    Science.gov (United States)

    Alibardi, Lorenzo

    2003-01-01

    Cells in the octopus cell area of the rat ventral cochlear nucleus have been connected to the monaural interpretation of spectral patterns of sound such as those derived from speech. This is possible by their fast onset of firing after each octopus cell and its dendrites have been contacted by many auditory fibres carrying different frequencies. The cytological characteristics that make these large cells able to perform such a function have been studied with ultrastructural immunocytochemistry for glycine, GABA and glutamate, and compared to that of other multipolar neurons of other regions of the ventral cochlear nucleus. Cells in the octopus cell area have an ultrastructure similar to large-giant D-multipolar neurons present in other areas of the cochlear nucleus, from which they differ by the presence of a larger excitatory axo-somatic synaptic input and larger mitochondria. Octopus cells are glycine and GABA negative, and glutamate positive with different degree. Large octopus cells receive more axo-somatic boutons than smaller octopus cells. Fusiform octopus cells are found sparsely within the intermediate acoustic striae. These cells are large to giant excitatory neurons (23-35 microm) with 62-85% of their irregular perimeter covered with large axo-somatic synaptic boutons. Most boutons contain round vesicles and are glycine and GABA negative but glutamate positive. The latter excitatory boutons represent about 70% of the input to octopus cells. Glycine positive boutons with flat and pleomorphic vesicles account for 9-10% of the input while GABA-ergic boutons with pleomorphic vesicles represent about 20% of the synaptic input. Other few, multipolar cells within the rat octopus cell area are surrounded by more inhibitory than excitatory terminals which contain flat and pleomorphic vesicles, a feature distinctive from that of true octopus cells. The latter resemble multipolar cells seen outside the octopus cell area that project to the contralateral inferior

  20. Planar cell polarity aligns osteoblast division in response to substrate strain.

    Science.gov (United States)

    Galea, Gabriel L; Meakin, Lee B; Savery, Dawn; Taipaleenmaki, Hanna; Delisser, Peter; Stein, Gary S; Copp, Andrew J; van Wijnen, Andre J; Lanyon, Lance E; Price, Joanna S

    2015-03-01

    Exposure of bone to dynamic strain increases the rate of division of osteoblasts and also influences the directional organization of the cellular and molecular structure of the bone tissue that they produce. Here, we report that brief exposure to dynamic substrate strain (sufficient to rapidly stimulate cell division) influences the orientation of osteoblastic cell division. The initial proliferative response to strain involves canonical Wnt signaling and can be blocked by sclerostin. However, the strain-related orientation of cell division is independently influenced through the noncanonical Wnt/planar cell polarity (PCP) pathway. Blockade of Rho-associated coiled kinase (ROCK), a component of the PCP pathway, prevents strain-related orientation of division in osteoblast-like Saos-2 cells. Heterozygous loop-tail mutation of the core PCP component van Gogh-like 2 (Vangl2) in mouse osteoblasts impairs the orientation of division in response to strain. Examination of bones from Vangl2 loop-tail heterozygous mice by µCT and scanning electron microscopy reveals altered bone architecture and disorganized bone-forming surfaces. Hence, in addition to the well-accepted role of PCP involvement in response to developmental cues during skeletal morphogenesis, our data reveal that this pathway also acts postnatally, in parallel with canonical Wnt signaling, to transduce biomechanical cues into skeletal adaptive responses. The simultaneous and independent actions of these two pathways appear to influence both the rate and orientation of osteoblast division, thus fine-tuning bone architecture to meet the structural demands of functional loading.

  1. The three-dimensional organization of telomeres in the nucleus of mammalian cells

    Directory of Open Access Journals (Sweden)

    Perrin Mathilde

    2004-06-01

    Full Text Available Abstract Background The observation of multiple genetic markers in situ by optical microscopy and their relevance to the study of three-dimensional (3D chromosomal organization in the nucleus have been greatly developed in the last decade. These methods are important in cancer research because cancer is characterized by multiple alterations that affect the modulation of gene expression and the stability of the genome. It is, therefore, essential to analyze the 3D genome organization of the interphase nucleus in both normal and cancer cells. Results We describe a novel approach to study the distribution of all telomeres inside the nucleus of mammalian cells throughout the cell cycle. It is based on 3D telomere fluorescence in situ hybridization followed by quantitative analysis that determines the telomeres' distribution in the nucleus throughout the cell cycle. This method enables us to determine, for the first time, that telomere organization is cell-cycle dependent, with assembly of telomeres into a telomeric disk in the G2 phase. In tumor cells, the 3D telomere organization is distorted and aggregates are formed. Conclusions The results emphasize a non-random and dynamic 3D nuclear telomeric organization and its importance to genomic stability. Based on our findings, it appears possible to examine telomeric aggregates suggestive of genomic instability in individual interphase nuclei and tissues without the need to examine metaphases. Such new avenues of monitoring genomic instability could potentially impact on cancer biology, genetics, diagnostic innovations and surveillance of treatment response in medicine.

  2. Differentiation of Mesenchymal Stem Cells into Nucleus Pulposus Cells In Vitro

    Institute of Scientific and Technical Information of China (English)

    Fenghua TAO; Feng LI; Guanghui LI; Feng PAN

    2008-01-01

    To find a new source of seed cells for constructing tissue-engineered intervertebral disc, nucleus pulposus (NP) cells and mesenchymal stem cells (MSCs) were isolated from New Zealand white rabbits. The nuclcus pulposus cells population was fluorescence-laelled and co-cultured with MSCs with or without direct contact. Morphological changes were observed every 12 h. Semi-quantitaive reverse transcriptase-polymerase chain reaction was performed to assess the expression levels of Sox-9, aggreacan and type Ⅱ collagen every 24 h after the co-culture. MSCs treated with direct contact rounded up and presented a ring-like appearance. The expression of marker genes was significantly increased when cells were co-cultured with direct contact for 24 h. No significant change was found after coculture without direct contact. Co-culture of NP cells and MSCs with direct contact is a reliable method for generating large amount of NP cells used for cell-based tissue engineering therapy.

  3. Mycobacterium tuberculosis CwsA overproduction modulates cell division and cell wall synthesis.

    Science.gov (United States)

    Plocinski, P; Martinez, L; Sarva, K; Plocinska, R; Madiraju, M; Rajagopalan, M

    2013-12-01

    We recently showed that two small membrane proteins of Mycobacterium tuberculosis, CwsA and CrgA, interact with each other, and that loss of CwsA in M. smegmatis is associated with defects in the cell division and cell wall synthesis processes. Here we show that CwsA overproduction also affected growth, cell division and cell shape of M. smegmatis and M. tuberculosis. CwsA overproduction in M. tuberculosis led to increased sensitivity to cefsulodin, a penicillin-binding protein (PBP) 1A/1B targeting beta (β) -lactam, but was unaffected by other β-lactams and vancomycin. A M. smegmatis cwsA overexpressing strain showed bulgy cells, increased fluorescent vancomycin staining and altered localization of Wag31-mCherry fusion protein. However, the levels of phosphorylated Wag31, important for optimal peptidoglycan synthesis and growth in mycobacteria, were not affected. Interestingly, CwsA overproduction in E. coli led to the formation of large rounded cells that eventually lysed whereas the overproduction of FtsZ along with CwsA reversed this phenotype. Together, our results emphasize that optimal levels of CwsA are required for regulated cell wall synthesis, hence maintenance of cell shape, and that CwsA likely interacts with and modulates the activities of other cell wall synthetic components including PBPs.

  4. Lin-28 promotes symmetric stem cell division and drives adaptive growth in the adult Drosophila intestine.

    Science.gov (United States)

    Chen, Ching-Huan; Luhur, Arthur; Sokol, Nicholas

    2015-10-15

    Stem cells switch between asymmetric and symmetric division to expand in number as tissues grow during development and in response to environmental changes. The stem cell intrinsic proteins controlling this switch are largely unknown, but one candidate is the Lin-28 pluripotency factor. A conserved RNA-binding protein that is downregulated in most animals as they develop from embryos to adults, Lin-28 persists in populations of adult stem cells. Its function in these cells has not been previously characterized. Here, we report that Lin-28 is highly enriched in adult intestinal stem cells in the Drosophila intestine. lin-28 null mutants are homozygous viable but display defects in this population of cells, which fail to undergo a characteristic food-triggered expansion in number and have reduced rates of symmetric division as well as reduced insulin signaling. Immunoprecipitation of Lin-28-bound mRNAs identified Insulin-like Receptor (InR), forced expression of which completely rescues lin-28-associated defects in intestinal stem cell number and division pattern. Furthermore, this stem cell activity of lin-28 is independent of one well-known lin-28 target, the microRNA let-7, which has limited expression in the intestinal epithelium. These results identify Lin-28 as a stem cell intrinsic factor that boosts insulin signaling in intestinal progenitor cells and promotes their symmetric division in response to nutrients, defining a mechanism through which Lin-28 controls the adult stem cell division patterns that underlie tissue homeostasis and regeneration.

  5. Zebrafish neural tube morphogenesis requires Scribble-dependent oriented cell divisions.

    Science.gov (United States)

    Žigman, Mihaela; Trinh, Le A; Fraser, Scott E; Moens, Cecilia B

    2011-01-11

    How control of subcellular events in single cells determines morphogenesis on the scale of the tissue is largely unresolved. The stereotyped cross-midline mitoses of progenitors in the zebrafish neural keel provide a unique experimental paradigm for defining the role and control of single-cell orientation for tissue-level morphogenesis in vivo. We show here that the coordinated orientation of individual progenitor cell division in the neural keel is the cellular determinant required for morphogenesis into a neural tube epithelium with a single straight lumen. We find that Scribble is required for oriented cell division and that its function in this process is independent of canonical apicobasal and planar polarity pathways. We identify a role for Scribble in controlling clustering of α-catenin foci in dividing progenitors. Loss of either Scrib or N-cadherin results in abnormally oriented mitoses, reduced cross-midline cell divisions, and similar neural tube defects. We propose that Scribble-dependent nascent cell-cell adhesion clusters between neuroepithelial progenitors contribute to define orientation of their cell division. Finally, our data demonstrate that while oriented mitoses of individual cells determine neural tube architecture, the tissue can in turn feed back on its constituent cells to define their polarization and cell division orientation to ensure robust tissue morphogenesis.

  6. ESCRT-III mediated cell division in Sulfolobus acidocaldarius - a reconstitution perspective.

    Science.gov (United States)

    Härtel, Tobias; Schwille, Petra

    2014-01-01

    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 vacuolar protein sorting 4 (Vps4) and endosomal sorting complex required for transport-III (ESCRT-III). ESCRT-III is essential for several eukaryotic pathways, e.g., budding of intraluminal vesicles, or cytokinesis, whereas Vps4 dissociates the ESCRT-III complex from the membrane. Cell Division A (CdvA) 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 Sulfolobus acidocaldarius shows functional analogies to the Z ring observed in prokaryotes like Escherichia 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.

  7. 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.

  8. Extracellular Matrix Ligand and Stiffness Modulate Immature Nucleus Pulposus Cell-Cell Interactions

    Science.gov (United States)

    Gilchrist, Christopher L.; Darling, Eric M.; Chen, Jun; Setton, Lori A.

    2011-01-01

    The nucleus pulposus (NP) of the intervertebral disc functions to provide compressive load support in the spine, and contains cells that play a critical role in the generation and maintenance of this tissue. The NP cell population undergoes significant morphological and phenotypic changes during maturation and aging, transitioning from large, vacuolated immature cells arranged in cell clusters to a sparse population of smaller, isolated chondrocyte-like cells. These morphological and organizational changes appear to correlate with the first signs of degenerative changes within the intervertebral disc. The extracellular matrix of the immature NP is a soft, gelatinous material containing multiple laminin isoforms, features that are unique to the NP relative to other regions of the disc and that change with aging and degeneration. Based on this knowledge, we hypothesized that a soft, laminin-rich extracellular matrix environment would promote NP cell-cell interactions and phenotypes similar to those found in immature NP tissues. NP cells were isolated from porcine intervertebral discs and cultured in matrix environments of varying mechanical stiffness that were functionalized with various matrix ligands; cellular responses to periods of culture were assessed using quantitative measures of cell organization and phenotype. Results show that soft (<720 Pa), laminin-containing extracellular matrix substrates promote NP cell morphologies, cell-cell interactions, and proteoglycan production in vitro, and that this behavior is dependent upon both extracellular matrix ligand and substrate mechanical properties. These findings indicate that NP cell organization and phenotype may be highly sensitive to their surrounding extracellular matrix environment. PMID:22087260

  9. Extracellular matrix ligand and stiffness modulate immature nucleus pulposus cell-cell interactions.

    Directory of Open Access Journals (Sweden)

    Christopher L Gilchrist

    Full Text Available The nucleus pulposus (NP of the intervertebral disc functions to provide compressive load support in the spine, and contains cells that play a critical role in the generation and maintenance of this tissue. The NP cell population undergoes significant morphological and phenotypic changes during maturation and aging, transitioning from large, vacuolated immature cells arranged in cell clusters to a sparse population of smaller, isolated chondrocyte-like cells. These morphological and organizational changes appear to correlate with the first signs of degenerative changes within the intervertebral disc. The extracellular matrix of the immature NP is a soft, gelatinous material containing multiple laminin isoforms, features that are unique to the NP relative to other regions of the disc and that change with aging and degeneration. Based on this knowledge, we hypothesized that a soft, laminin-rich extracellular matrix environment would promote NP cell-cell interactions and phenotypes similar to those found in immature NP tissues. NP cells were isolated from porcine intervertebral discs and cultured in matrix environments of varying mechanical stiffness that were functionalized with various matrix ligands; cellular responses to periods of culture were assessed using quantitative measures of cell organization and phenotype. Results show that soft (<720 Pa, laminin-containing extracellular matrix substrates promote NP cell morphologies, cell-cell interactions, and proteoglycan production in vitro, and that this behavior is dependent upon both extracellular matrix ligand and substrate mechanical properties. These findings indicate that NP cell organization and phenotype may be highly sensitive to their surrounding extracellular matrix environment.

  10. The plant cell nucleus: a true arena for the fight between plants and pathogens.

    Science.gov (United States)

    Deslandes, Laurent; Rivas, Susana

    2011-01-01

    Communication between the cytoplasm and the nucleus is a fundamental feature shared by both plant and animal cells. Cellular factors involved in the transport of macromolecules through the nuclear envelope, including nucleoporins, importins and Ran-GTP related components, are conserved among a variety of eukaryotic systems. Interestingly, mutations in these nuclear components compromise resistance signalling, illustrating the importance of nucleocytoplasmic trafficking in plant innate immunity. Indeed, spatial restriction of defence regulators by the nuclear envelope and stimulus-induced nuclear translocation constitute an important level of defence-associated gene regulation in plants. A significant number of effectors from different microbial pathogens are targeted to the plant cell nucleus. In addition, key host factors, including resistance proteins, immunity components, transcription factors and transcriptional regulators shuttle between the cytoplasm and the nucleus, and their level of nuclear accumulation determines the output of the defence response, further confirming the crucial role played by the nucleus during the interaction between plants and pathogens. Here, we discuss recent findings that situate the nucleus at the frontline of the mutual recognition between plants and invading microbes.

  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

    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...

  12. Noc protein binds to specific DNA sequences to coordinate cell division with chromosome segregation.

    Science.gov (United States)

    Wu, Ling Juan; Ishikawa, Shu; Kawai, Yoshikazu; Oshima, Taku; Ogasawara, Naotake; Errington, Jeff

    2009-07-08

    Coordination of chromosome segregation and cytokinesis is crucial for efficient cell proliferation. In Bacillus subtilis, the nucleoid occlusion protein Noc protects the chromosomes by associating with the chromosome and preventing cell division in its vicinity. Using protein localization, ChAP-on-Chip and bioinformatics, we have identified a consensus Noc-binding DNA sequence (NBS), and have shown that Noc is targeted to about 70 discrete regions scattered around the chromosome, though absent from a large region around the replication terminus. Purified Noc bound specifically to an NBS in vitro. NBSs inserted near the replication terminus bound Noc-YFP and caused a delay in cell division. An autonomous plasmid carrying an NBS array recruited Noc-YFP and conferred a severe Noc-dependent inhibition of cell division. This shows that Noc is a potent inhibitor of division, but that its activity is strictly localized by the interaction with NBS sites in vivo. We propose that Noc serves not only as a spatial regulator of cell division to protect the nucleoid, but also as a timing device with an important role in the coordination of chromosome segregation and cell division.

  13. Three-Dimensional Organization of Chromosome Territories and the Human Interphase Cell Nucleus

    NARCIS (Netherlands)

    T.A. Knoch (Tobias); C. Münkel (Christian); J. Langowski (Jörg)

    1998-01-01

    textabstractTo study the three-dimensional organization of chromosome territories and the human interphase cell nucleus we developed models which could be compared to experiments. Despite the successful linear sequencing of the human genome its 3D-organization is widely unknown. Using Monte Carl

  14. Three-dimensional organization of chromosome territories in the human interphase cell nucleus

    NARCIS (Netherlands)

    T.A. Knoch (Tobias); C. Münkel (Christian); J. Langowski (Jörg)

    1999-01-01

    markdownabstractTo study the three-dimensional organization of chromosome territories and the human interphase cell nucleus we developed models which could be compared to experiments. Despite the successful linear sequencing of the human genome its 3D-organization is widely unknown. Using Monte Carl

  15. Three-Dimensional Organization of Chromosome Territories and the Human Cell Nucleus

    NARCIS (Netherlands)

    T.A. Knoch (Tobias)

    1999-01-01

    textabstractTo study the three-dimensional organization of chromosome territories and the human interphase cell nucleus we developed models, which could be compared to experiments. Despite the successful linear sequencing of the human genome its 3D-organization is widely unknown. Using Monte Car

  16. Nucleus Retroambiguus Projections To Lumbosacral Mononeuronal Cell Groups In The Male Cat.

    NARCIS (Netherlands)

    VanderHorst, Veronique G.J.M.; Holstege, Gert

    1997-01-01

    Recently, in the female cat, nucleus retroambiguus (NRA) projections have been described as distinct motoneuronal cell groups in the lumbar enlargement, possibly involved in lordosis behavior. The present study deals with the NRA-lumbosacral pathway in the male cat. Lumbosacral injections of wheat g

  17. Nucleus retroambiguous projections to lumbosacral motoneuronal cell groups in the male cat

    NARCIS (Netherlands)

    Vanderhorst, VGJM; Holstege, G

    1997-01-01

    Recently, in the female cat, nucleus retroambiguus (NRA) projections have been described as distinct motoneuronal cell groups in the lumbar enlargement, possibly involved in lordosis behavior. The present study deals with the NRA-lumbosacral pathway in the male cat, Lumbosacral injections of wheat g

  18. Concentration Sensing by the Moving Nucleus in Cell Fate Determination: A Computational Analysis.

    Directory of Open Access Journals (Sweden)

    Varun Aggarwal

    Full Text Available During development of the vertebrate neuroepithelium, the nucleus in neural progenitor cells (NPCs moves from the apex toward the base and returns to the apex (called interkinetic nuclear migration at which point the cell divides. The fate of the resulting daughter cells is thought to depend on the sampling by the moving nucleus of a spatial concentration profile of the cytoplasmic Notch intracellular domain (NICD. However, the nucleus executes complex stochastic motions including random waiting and back and forth motions, which can expose the nucleus to randomly varying levels of cytoplasmic NICD. How nuclear position can determine daughter cell fate despite the stochastic nature of nuclear migration is not clear. Here we derived a mathematical model for reaction, diffusion, and nuclear accumulation of NICD in NPCs during interkinetic nuclear migration (INM. Using experimentally measured trajectory-dependent probabilities of nuclear turning, nuclear waiting times and average nuclear speeds in NPCs in the developing zebrafish retina, we performed stochastic simulations to compute the nuclear trajectory-dependent probabilities of NPC differentiation. Comparison with experimentally measured nuclear NICD concentrations and trajectory-dependent probabilities of differentiation allowed estimation of the NICD cytoplasmic gradient. Spatially polarized production of NICD, rapid NICD cytoplasmic consumption and the time-averaging effect of nuclear import/export kinetics are sufficient to explain the experimentally observed differentiation probabilities. Our computational studies lend quantitative support to the feasibility of the nuclear concentration-sensing mechanism for NPC fate determination in zebrafish retina.

  19. THE COMPLEX ORGANIZATION OF EUKARYOTIC CELL NUCLEUS: THE NUCLEAR BODIES (I

    Directory of Open Access Journals (Sweden)

    Cristian Campeanu

    2012-10-01

    Full Text Available Identified short time after the discovery of cells, over 300 years ago, the cell nucleus of eukaryotes continuously focused the interest of scientists, which used increasingly sophisticated research tools to clarify its complex structure and functions. The results of all these studies, especially those carried out in the second half of the past century, proved and confirmed that the eukaryotic cell nucleus is the control center of all cellular activities and also ensures the continuity of genetic information along successive generations of cells. These vital functions are the result of selective expression of genes contained in the nuclear chromatin, which is a high ordered and dynamic structure, in permanent and bilateral relations with other nuclear components. Based on these considerations, the present review aims to synthetize the latest researches and concepts about the cell nuclear territory in three distinctive parts, according to the complexity of the topic

  20. Tension-oriented cell divisions limit anisotropic tissue tension in epithelial spreading during zebrafish epiboly.

    Science.gov (United States)

    Campinho, Pedro; Behrndt, Martin; Ranft, Jonas; Risler, Thomas; Minc, Nicolas; Heisenberg, Carl-Philipp

    2013-12-01

    Epithelial spreading is a common and fundamental aspect of various developmental and disease-related processes such as epithelial closure and wound healing. A key challenge for epithelial tissues undergoing spreading is to increase their surface area without disrupting epithelial integrity. Here we show that orienting cell divisions by tension constitutes an efficient mechanism by which the enveloping cell layer (EVL) releases anisotropic tension while undergoing spreading during zebrafish epiboly. The control of EVL cell-division orientation by tension involves cell elongation and requires myosin II activity to align the mitotic spindle with the main tension axis. We also found that in the absence of tension-oriented cell divisions and in the presence of increased tissue tension, EVL cells undergo ectopic fusions, suggesting that the reduction of tension anisotropy by oriented cell divisions is required to prevent EVL cells from fusing. We conclude that cell-division orientation by tension constitutes a key mechanism for limiting tension anisotropy and thus promoting tissue spreading during EVL epiboly.

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

    Energy Technology Data Exchange (ETDEWEB)

    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 (/sup 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 ..beta..-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-/sup 3/H. MCPs are examined in flagellated and non-flagellated vesicles prepared from cells by immunoaffinity chromatography.

  2. Condensation of FtsZ filaments can drive bacterial cell division.

    Science.gov (United States)

    Lan, Ganhui; Daniels, Brian R; Dobrowsky, Terrence M; Wirtz, Denis; Sun, Sean X

    2009-01-06

    Forces are important in biological systems for accomplishing key cell functions, such as motility, organelle transport, and cell division. Currently, known force generation mechanisms typically involve motor proteins. In bacterial cells, no known motor proteins are involved in cell division. Instead, a division ring (Z-ring) consists of mostly FtsZ, FtsA, and ZipA is used to exerting a contractile force. The mechanism of force generation in bacterial cell division is unknown. Using computational modeling, we show that Z-ring formation results from the colocalization of FtsZ and FtsA mediated by the favorable alignment of FtsZ polymers. The model predicts that the Z-ring undergoes a condensation transition from a low-density state to a high-density state and generates a sufficient contractile force to achieve division. FtsZ GTP hydrolysis facilitates monomer turnover during the condensation transition, but does not directly generate forces. In vivo fluorescence measurements show that FtsZ density increases during division, in accord with model results. The mechanism is akin to van der Waals picture of gas-liquid condensation, and shows that organisms can exploit microphase transitions to generate mechanical forces.

  3. Releasing dentate nucleus cells from Purkinje cell inhibition generates output from the cerebrocerebellum.

    Directory of Open Access Journals (Sweden)

    Takahiro Ishikawa

    Full Text Available The cerebellum generates its vast amount of output to the cerebral cortex through the dentate nucleus (DN that is essential for precise limb movements in primates. Nuclear cells in DN generate burst activity prior to limb movement, and inactivation of DN results in cerebellar ataxia. The question is how DN cells become active under intensive inhibitory drive from Purkinje cells (PCs. There are two excitatory inputs to DN, mossy fiber and climbing fiber collaterals, but neither of them appears to have sufficient strength for generation of burst activity in DN. Therefore, we can assume two possible mechanisms: post-inhibitory rebound excitation and disinhibition. If rebound excitation works, phasic excitation of PCs and a concomitant inhibition of DN cells should precede the excitation of DN cells. On the other hand, if disinhibition plays a primary role, phasic suppression of PCs and activation of DN cells should be observed at the same timing. To examine these two hypotheses, we compared the activity patterns of PCs in the cerebrocerebellum and DN cells during step-tracking wrist movements in three Japanese monkeys. As a result, we found that the majority of wrist-movement-related PCs were suppressed prior to movement onset and the majority of wrist-movement-related DN cells showed concurrent burst activity without prior suppression. In a minority of PCs and DN cells, movement-related increases and decreases in activity, respectively, developed later. These activity patterns suggest that the initial burst activity in DN cells is generated by reduced inhibition from PCs, i.e., by disinhibition. Our results indicate that suppression of PCs, which has been considered secondary to facilitation, plays the primary role in generating outputs from DN. Our findings provide a new perspective on the mechanisms used by PCs to influence limb motor control and on the plastic changes that underlie motor learning in the cerebrocerebellum.

  4. 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.

  5. The multiple functions of T stellate/multipolar/chopper cells in the ventral cochlear nucleus.

    Science.gov (United States)

    Oertel, Donata; Wright, Samantha; Cao, Xiao-Jie; Ferragamo, Michael; Bal, Ramazan

    2011-06-01

    Acoustic information is brought to the brain by auditory nerve fibers, all of which terminate in the cochlear nuclei, and is passed up the auditory pathway through the principal cells of the cochlear nuclei. A population of neurons variously known as T stellate, type I multipolar, planar multipolar, or chopper cells forms one of the major ascending auditory pathways through the brainstem. T Stellate cells are sharply tuned; as a population they encode the spectrum of sounds. In these neurons, phasic excitation from the auditory nerve is made more tonic by feedforward excitation, coactivation of inhibitory with excitatory inputs, relatively large excitatory currents through NMDA receptors, and relatively little synaptic depression. The mechanisms that make firing tonic also obscure the fine structure of sounds that is represented in the excitatory inputs from the auditory nerve and account for the characteristic chopping response patterns with which T stellate cells respond to tones. In contrast with other principal cells of the ventral cochlear nucleus (VCN), T stellate cells lack a low-voltage-activated potassium conductance and are therefore sensitive to small, steady, neuromodulating currents. The presence of cholinergic, serotonergic and noradrenergic receptors allows the excitability of these cells to be modulated by medial olivocochlear efferent neurons and by neuronal circuits associated with arousal. T Stellate cells deliver acoustic information to the ipsilateral dorsal cochlear nucleus (DCN), ventral nucleus of the trapezoid body (VNTB), periolivary regions around the lateral superior olivary nucleus (LSO), and to the contralateral ventral lemniscal nuclei (VNLL) and inferior colliculus (IC). It is likely that T stellate cells participate in feedback loops through both medial and lateral olivocochlear efferent neurons and they may be a source of ipsilateral excitation of the LSO.

  6. Nonlinear optical imaging and Raman microspectrometry of the cell nucleus throughout the cell cycle.

    Science.gov (United States)

    Pliss, Artem; Kuzmin, Andrey N; Kachynski, Aliaksandr V; Prasad, Paras N

    2010-11-17

    Fundamental understanding of cellular processes at molecular level is of considerable importance in cell biology as well as in biomedical disciplines for early diagnosis of infection and cancer diseases, and for developing new molecular medicine-based therapies. Modern biophotonics offers exclusive capabilities to obtain information on molecular composition, organization, and dynamics in a cell by utilizing a combination of optical spectroscopy and optical imaging. We introduce here a combination of Raman microspectrometry, together with coherent anti-Stokes Raman scattering (CARS) and two-photon excited fluorescence (TPEF) nonlinear optical microscopy, to study macromolecular organization of the nucleus throughout the cell cycle. Site-specific concentrations of proteins, DNA, RNA, and lipids were determined in nucleoli, nucleoplasmic transcription sites, nuclear speckles, constitutive heterochromatin domains, mitotic chromosomes, and extrachromosomal regions of mitotic cells by quantitative confocal Raman microspectrometry. A surprising finding, obtained in our study, is that the local concentration of proteins does not increase during DNA compaction. We also demonstrate that postmitotic DNA decondensation is a gradual process, continuing for several hours. The quantitative Raman spectroscopic analysis was corroborated with CARS/TPEF multimodal imaging to visualize the distribution of protein, DNA, RNA, and lipid macromolecules throughout the cell cycle.

  7. 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 ...

  8. Communication Between the Cell Membrane and the Nucleus: Role of Protein Compartmentalization

    Energy Technology Data Exchange (ETDEWEB)

    Lelievre, Sophie A; Bissell, Mina J

    1998-10-21

    Understanding how the information is conveyed from outside to inside the cell is a critical challenge for all biologists involved in signal transduction. The flow of information initiated by cell-cell and cell-extracellular matrix contacts is mediated by the formation of adhesion complexes involving multiple proteins. Inside adhesion complexes, connective membrane skeleton (CMS) proteins are signal transducers that bind to adhesion molecules, organize the cytoskeleton, and initiate biochemical cascades. Adhesion complex-mediated signal transduction ultimately directs the formation of supramolecular structures in the cell nucleus, as illustrated by the establishment of multi complexes of DNA-bound transcription factors, and the redistribution of nuclear structural proteins to form nuclear subdomains. Recently, several CMS proteins have been observed to travel to the cell nucleus, suggesting a distinctive role for these proteins in signal transduction. This review focuses on the nuclear translocation of structural signal transducers of the membrane skeleton and also extends our analysis to possible translocation of resident nuclear proteins to the membrane skeleton. This leads us to envision the communication between spatially distant cellular compartments (i.e., membrane skeleton and cell nucleus) as a bidirectional flow of information (a dynamic reciprocity) based on subtle multilevel structural and biochemical equilibria. At one level, it is mediated by the interaction between structural signal transducers and their binding partners, at another level it may be mediated by the balance and integration of signal transducers in different cellular compartments.

  9. Sex and the eukaryotic cell cycle is consistent with a viral ancestry for the eukaryotic nucleus.

    Science.gov (United States)

    Bell, Philip John Livingstone

    2006-11-07

    The origin of the eukaryotic cell cycle, including mitosis, meiosis, and sex are as yet unresolved aspects of the evolution of the eukaryotes. The wide phylogenetic distribution of both mitosis and meiosis suggest that these processes are integrally related to the origin of the earliest eukaryotic cells. According to the viral eukaryogenesis (VE) hypothesis, the eukaryotes are a composite of three phylogenetically unrelated organisms: a viral lysogen that evolved into the nucleus, an archaeal cell that evolved into the eukaryotic cytoplasm, and an alpha-proteobacterium that evolved into the mitochondria. In the extended VE hypothesis presented here, the eukaryotic cell cycle arises as a consequence of the derivation of the nucleus from a lysogenic DNA virus.

  10. Mechanisms of regulating cell topology in proliferating epithelia: impact of division plane, mechanical forces, and cell memory.

    Directory of Open Access Journals (Sweden)

    Yingzi Li

    Full Text Available Regulation of cell growth and cell division has a fundamental role in tissue formation, organ development, and cancer progression. Remarkable similarities in the topological distributions were found in a variety of proliferating epithelia in both animals and plants. At the same time, there are species with significantly varied frequency of hexagonal cells. Moreover, local topology has been shown to be disturbed on the boundary between proliferating and quiescent cells, where cells have fewer sides than natural proliferating epithelia. The mechanisms of regulating these topological changes remain poorly understood. In this study, we use a mechanical model to examine the effects of orientation of division plane, differential proliferation, and mechanical forces on animal epithelial cells. We find that regardless of orientation of division plane, our model can reproduce the commonly observed topological distributions of cells in natural proliferating animal epithelia with the consideration of cell rearrangements. In addition, with different schemes of division plane, we are able to generate different frequency of hexagonal cells, which is consistent with experimental observations. In proliferating cells interfacing quiescent cells, our results show that differential proliferation alone is insufficient to reproduce the local changes in cell topology. Rather, increased tension on the boundary, in conjunction with differential proliferation, can reproduce the observed topological changes. We conclude that both division plane orientation and mechanical forces play important roles in cell topology in animal proliferating epithelia. Moreover, cell memory is also essential for generating specific topological distributions.

  11. Mechanisms of regulating cell topology in proliferating epithelia: impact of division plane, mechanical forces, and cell memory.

    Science.gov (United States)

    Li, Yingzi; Naveed, Hammad; Kachalo, Sema; Xu, Lisa X; Liang, Jie

    2012-01-01

    Regulation of cell growth and cell division has a fundamental role in tissue formation, organ development, and cancer progression. Remarkable similarities in the topological distributions were found in a variety of proliferating epithelia in both animals and plants. At the same time, there are species with significantly varied frequency of hexagonal cells. Moreover, local topology has been shown to be disturbed on the boundary between proliferating and quiescent cells, where cells have fewer sides than natural proliferating epithelia. The mechanisms of regulating these topological changes remain poorly understood. In this study, we use a mechanical model to examine the effects of orientation of division plane, differential proliferation, and mechanical forces on animal epithelial cells. We find that regardless of orientation of division plane, our model can reproduce the commonly observed topological distributions of cells in natural proliferating animal epithelia with the consideration of cell rearrangements. In addition, with different schemes of division plane, we are able to generate different frequency of hexagonal cells, which is consistent with experimental observations. In proliferating cells interfacing quiescent cells, our results show that differential proliferation alone is insufficient to reproduce the local changes in cell topology. Rather, increased tension on the boundary, in conjunction with differential proliferation, can reproduce the observed topological changes. We conclude that both division plane orientation and mechanical forces play important roles in cell topology in animal proliferating epithelia. Moreover, cell memory is also essential for generating specific topological distributions.

  12. Perturbation of nucleo-cytoplasmic transport affects size of nucleus and nucleolus in human cells.

    Science.gov (United States)

    Ganguly, Abira; Bhattacharjee, Chumki; Bhave, Madhura; Kailaje, Vaishali; Jain, Bhawik K; Sengupta, Isha; Rangarajan, Annapoorni; Bhattacharyya, Dibyendu

    2016-03-01

    Size regulation of human cell nucleus and nucleolus are poorly understood subjects. 3D reconstruction of live image shows that the karyoplasmic ratio (KR) increases by 30-80% in transformed cell lines compared to their immortalized counterpart. The attenuation of nucleo-cytoplasmic transport causes the KR value to increase by 30-50% in immortalized cell lines. Nucleolus volumes are significantly increased in transformed cell lines and the attenuation of nucleo-cytoplasmic transport causes a significant increase in the nucleolus volume of immortalized cell lines. A cytosol and nuclear fraction swapping experiment emphasizes the potential role of unknown cytosolic factors in nuclear and nucleolar size regulation.

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

    OpenAIRE

    Cavalier-Smith Thomas

    2010-01-01

    Abstract Background The transition from prokaryotes to eukaryotes was the most radical change in cell organisation since life began, with the largest ever burst of gene duplication and novelty. According to the coevolutionary theory of eukaryote origins, the fundamental innovations were the concerted origins of the endomembrane system and cytoskeleton, subsequently recruited to form the cell nucleus and coevolving mitotic apparatus, with numerous genetic eukaryotic novelties inevitable conseq...

  14. HEK293 cells express dystrophin Dp71 with nucleus-specific localization of Dp71ab.

    Science.gov (United States)

    Nishida, Atsushi; Yasuno, Sato; Takeuchi, Atsuko; Awano, Hiroyuki; Lee, Tomoko; Niba, Emma Tabe Eko; Fujimoto, Takahiro; Itoh, Kyoko; Takeshima, Yasuhiro; Nishio, Hisahide; Matsuo, Masafumi

    2016-09-01

    The dystrophin gene consists of 79 exons and encodes tissue-specific isoforms. Mutations in the dystrophin gene cause Duchenne muscular dystrophy, of which a substantial proportion of cases are complicated by non-progressive mental retardation. Abnormalities of Dp71, an isoform transcribed from a promoter in intron 62, are a suspected cause of mental retardation. However, the roles of Dp71 in human brain have not been fully elucidated. Here, we characterized dystrophin in human HEK293 cells with the neuronal lineage. Reverse transcription-PCR amplification of the full-length dystrophin transcript revealed the absence of fragments covering the 5' part of the dystrophin cDNA. In contrast, fragments covering exons 64-79 were present. The Dp71 promoter-specific exon G1 was shown spliced to exon 63. We demonstrated that the Dp71 transcript comprised two subisoforms: one lacking exon 78 (Dp71b) and the other lacking both exons 71 and 78 (Dp71ab). Western blotting of cell lysates using an antibody against the dystrophin C-terminal region revealed two bands, corresponding to Dp71b and Dp71ab. Immunohistochemical examination with the dystrophin antibody revealed scattered punctate signals in the cytoplasm and the nucleus. Western blotting revealed one band corresponding to Dp71b in the cytoplasm and two bands corresponding to Dp71b and Dp71ab in the nucleus, with Dp71b being predominant. These results indicated that Dp71ab is a nucleus-specific subisoform. We concluded that Dp71, comprising Dp71b and Dp71ab, was expressed exclusively in HEK293 cells and that Dp71ab was specifically localized to the nucleus. Our findings suggest that Dp71ab in the nucleus contributes to the diverse functions of HEK293 cells.

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

    Science.gov (United States)

    van der Ploeg, René; Verheul, Jolanda; Vischer, Norbert O E; Alexeeva, Svetlana; Hoogendoorn, Eelco; Postma, Marten; Banzhaf, Manuel; Vollmer, Waldemar; den Blaauwen, Tanneke

    2013-03-01

    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, respectively, which catalyse peptidoglycan extension and maturation. Endogenous immunolabelled PBP2 localized in the cylindrical part of the cell as well as transiently at midcell. Using the novel image analysis tool Coli-Inspector to analyse protein localization as function of the bacterial cell age, we compared PBP2 localization with that of other E. coli cell elongation and division proteins including PBP3. Interestingly, the midcell localization of the two transpeptidases overlaps in time during the early period of divisome maturation. Försters Resonance Energy Transfer (FRET) experiments revealed an interaction between PBP2 and PBP3 when both are present at midcell. A decrease in the midcell diameter is visible after 40% of the division cycle indicating that the onset of new cell pole synthesis starts much earlier than previously identified by visual inspection. The data support a new model of the division cycle in which the elongasome and divisome interact to prepare for cell division.

  16. Polarity and cell division orientation in the cleavage embryo: from worm to human

    Science.gov (United States)

    Ajduk, Anna; Zernicka-Goetz, Magdalena

    2016-01-01

    Cleavage is a period after fertilization, when a 1-cell embryo starts developing into a multicellular organism. Due to a series of mitotic divisions, the large volume of a fertilized egg is divided into numerous smaller, nucleated cells—blastomeres. Embryos of different phyla divide according to different patterns, but molecular mechanism of these early divisions remains surprisingly conserved. In the present paper, we describe how polarity cues, cytoskeleton and cell-to-cell communication interact with each other to regulate orientation of the early embryonic division planes in model animals such as Caenorhabditis elegans, Drosophila and mouse. We focus particularly on the Par pathway and the actin-driven cytoplasmic flows that accompany it. We also describe a unique interplay between Par proteins and the Hippo pathway in cleavage mammalian embryos. Moreover, we discuss the potential meaning of polarity, cytoplasmic dynamics and cell-to-cell communication as quality biomarkers of human embryos. PMID:26660321

  17. 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.

  18. DNA damage-induced translocation of S100A11 into the nucleus regulates cell proliferation

    Directory of Open Access Journals (Sweden)

    Ulbricht Tobias

    2010-12-01

    Full Text Available Abstract Background Proteins are able to react in response to distinct stress stimuli by alteration of their subcellular distribution. The stress-responsive protein S100A11 belongs to the family of multifunctional S100 proteins which have been implicated in several key biological processes. Previously, we have shown that S100A11 is directly involved in DNA repair processes at damaged chromatin in the nucleus. To gain further insight into the underlying mechanism subcellular trafficking of S100A11 in response to DNA damage was analyzed. Results We show that DNA damage induces a nucleolin-mediated translocation of S100A11 from the cytoplasm into the nucleus. This translocation is impeded by inhibition of the phosphorylation activity of PKCα. Translocation of S100A11 into the nucleus correlates with an increased cellular p21 protein level. Depletion of nucleolin by siRNA severely impairs translocation of S100A11 into the nucleus resulting in a decreased p21 protein level. Additionally, cells lacking nucleolin showed a reduced colony forming capacity. Conclusions These observations suggest that regulation of the subcellular distribution of S100A11 plays an important role in the DNA damage response and p21-mediated cell cycle control.

  19. Electrical signals polarize neuronal organelles, direct neuron migration, and orient cell division.

    Science.gov (United States)

    Yao, Li; McCaig, Colin D; Zhao, Min

    2009-09-01

    During early brain development, the axis of division of neuronal precursor cells is regulated tightly and can determine whether neurons remain in the germinal layers or migrate away. Directed neuronal migration depends on the establishment of cell polarity, and cells are polarized dynamically in response to extracellular signals. Endogenous electric fields (EFs) orient cell division and direct migration of a variety of cell types. Here, we show that cell division of cultured hippocampal cells (neuron-like cells and glial-like cells) is oriented strikingly by an applied EF, which also directs neuronal migration. Directed migration involves polarization of the leading neurite, of the microtubule-associated protein MAP-2 and of the Golgi apparatus and the centrosome, all of which reposition asymmetrically to face the cathode. Pharmacological inhibition of Rho-associated coiled-coil forming protein kinases (ROCK) and phosphoinositide 3-kinase decreased, leading neurite orientation and Golgi polarization in the neurons in response to an EF and in parallel decreased the directedness of EF-guided neuronal migration. This work demonstrates that the axis of hippocampal cell division, the establishment of neuronal polarity, the polarization of intracellular structures, and the direction of neuronal migration are all regulated by an extracellular electrical cue.

  20. Formation of tRNA granules in the nucleus of heat-induced human cells

    Energy Technology Data Exchange (ETDEWEB)

    Miyagawa, Ryu [Radioisotope Center, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032 (Japan); Department of Biological Science, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654 (Japan); Mizuno, Rie [Radioisotope Center, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032 (Japan); Watanabe, Kazunori, E-mail: watanabe@ric.u-tokyo.ac.jp [Radioisotope Center, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032 (Japan); Ijiri, Kenichi [Radioisotope Center, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032 (Japan); Department of Biological Science, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654 (Japan)

    2012-02-03

    Highlights: Black-Right-Pointing-Pointer tRNAs are tranlocated into the nucleus in heat-induced HeLa cells. Black-Right-Pointing-Pointer tRNAs form the unique granules in the nucleus. Black-Right-Pointing-Pointer tRNA ganules overlap with nuclear stress granules. -- Abstract: The stress response, which can trigger various physiological phenomena, is important for living organisms. For instance, a number of stress-induced granules such as P-body and stress granule have been identified. These granules are formed in the cytoplasm under stress conditions and are associated with translational inhibition and mRNA decay. In the nucleus, there is a focus named nuclear stress body (nSB) that distinguishes these structures from cytoplasmic stress granules. Many splicing factors and long non-coding RNA species localize in nSBs as a result of stress. Indeed, tRNAs respond to several kinds of stress such as heat, oxidation or starvation. Although nuclear accumulation of tRNAs occurs in starved Saccharomyces cerevisiae, this phenomenon is not found in mammalian cells. We observed that initiator tRNA{sup Met} (Meti) is actively translocated into the nucleus of human cells under heat stress. During this study, we identified unique granules of Meti that overlapped with nSBs. Similarly, elongator tRNA{sup Met} was translocated into the nucleus and formed granules during heat stress. Formation of tRNA granules is closely related to the translocation ratio. Then, all tRNAs may form the specific granules.

  1. Temporal properties of pattern adaptation of relay cells in the lateral geniculate nucleus of cats

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The temporal properties of pattern adaptation of relay cells induced by repeated sinusoidal drifting grating were investigated in the dorsal lateral geniculate nucleus (dLGN) of cats. The results showed that the response amplitude declined and the response latency prolonged when relay cells were pattern-adapted in dLGN, like the similar fmdings in visual cortex. However, in contrast to the result in cortex,the response phase of relay cells advanced. This implies that an inhibition with relatively long latency may participate in the pattern adaptation of dLGN cells and the adaptation in dLGN may be via a mechanism different from that of visual cortex.``

  2. MIRO1 influences the morphology and intracellular distribution of mitochondria during embryonic cell division in Arabidopsis.

    Science.gov (United States)

    Yamaoka, Shohei; Nakajima, Masaki; Fujimoto, Masaru; Tsutsumi, Nobuhiro

    2011-02-01

    Regulating the morphology and intracellular distribution of mitochondria is essential for embryo development in animals. However, the importance of such regulation is not clearly defined in plants. The evolutionarily conserved Miro proteins are known to be involved in the regulation of mitochondrial morphology and motility. We previously demonstrated that MIRO1, an Arabidopsis thaliana orthologue of the Miro protein, is required for embryogenesis. An insertional mutation in the MIRO1 gene causes arrest of embryonic cell division, leading to abortion of the embryo at an early stage. Here we investigated the role of MIRO1 in the regulation of mitochondrial behaviour in egg cells and early-stage embryos using GFP-labeled mitochondria. Two-photon laser scanning microscopy revealed that, in miro1 mutant egg cells, mitochondria are abnormally enlarged, although egg cell formation is nearly unaffected. After fertilization and subsequent zygotic cell division, the homozygous miro1 mutant two-celled embryo contained a significantly reduced number of mitochondria in its apical cell compared with the wild type, suggesting that the miro1 mutation inhibits proper intracellular distribution of mitochondria, leading to an arrest of embryonic cell division. Our findings suggest that proper mitochondrial morphology and intracellular distribution are maintained by MIRO1 and are vital for embryonic cell division.

  3. Spire, an actin nucleation factor, regulates cell division during Drosophila heart development.

    Directory of Open Access Journals (Sweden)

    Peng Xu

    Full Text Available The Drosophila dorsal vessel is a beneficial model system for studying the regulation of early heart development. Spire (Spir, an actin-nucleation factor, regulates actin dynamics in many developmental processes, such as cell shape determination, intracellular transport, and locomotion. Through protein expression pattern analysis, we demonstrate that the absence of spir function affects cell division in Myocyte enhancer factor 2-, Tinman (Tin-, Even-skipped- and Seven up (Svp-positive heart cells. In addition, genetic interaction analysis shows that spir functionally interacts with Dorsocross, tin, and pannier to properly specify the cardiac fate. Furthermore, through visualization of double heterozygous embryos, we determines that spir cooperates with CycA for heart cell specification and division. Finally, when comparing the spir mutant phenotype with that of a CycA mutant, the results suggest that most Svp-positive progenitors in spir mutant embryos cannot undergo full cell division at cell cycle 15, and that Tin-positive progenitors are arrested at cell cycle 16 as double-nucleated cells. We conclude that Spir plays a crucial role in controlling dorsal vessel formation and has a function in cell division during heart tube morphogenesis.

  4. An autoantibody is modified for use as a delivery system to target the cell nucleus: therapeutic implications.

    Science.gov (United States)

    Weisbart, R H; Stempniak, M; Harris, S; Zack, D J; Ferreri, K

    1998-10-01

    A murine monoclonal anti-dsDNA antibody was found to penetrate living cells and localize in the nucleus without pathologic effects. A single mutation in VH markedly enhanced cellular penetration. The mutant antibody was produced as recombinant Fab and single chain antibody fragments to investigate its use as a delivery system to target the cell nucleus. Complexes were made containing Fab fragments and alkaline phosphatase conjugated goat antibodies to mouse |gk chains. Fab fragments transported 305 kDa goat antibody-enzyme complexes into the nucleus in COS-7 and CHO cells. A single chain antibody cDNA was constructed by splice overlap extension PCR and expressed in COS-7 cells. Binding of the single chain antibody to dsDNA was shown by ELISA, and cellular penetration and nuclear localization were demonstrated in COS-7 and CHO cells. The single chain antibody cDNA was ligated into the expression vector, pEGFP, to produce a fusion protein with green fluorescent protein. The fusion protein penetrated COS-7 cells and localized in the cell nucleus. The single chain antibody produced during sustained expression in CHO cells re-entered antibody-producing cells and localized in the nucleus without affecting cell viability. Our results demonstrate the potential use of a modified autoantibody as a delivery system to target the cell nucleus.

  5. Cell wall growth during elongation and division : one ring to bind them?

    NARCIS (Netherlands)

    Scheffers, Dirk-Jan

    2007-01-01

    The role of the cell division protein FtsZ in bacterial cell wall (CW) synthesis is believed to be restricted to localizing proteins involved in the synthesis of the septal wall. Elsewhere, compelling evidence is provided that in Caulobacter crescentus, FtsZ plays an additional role in CW synthesis

  6. 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, respe

  7. Interaction Network among Escherichia coli Membrane Proteins Involved in Cell Division as Revealed by Bacterial Two-Hybrid Analysis

    OpenAIRE

    Karimova, Gouzel; Dautin, Nathalie; Ladant, Daniel

    2005-01-01

    Formation of the Escherichia coli division septum is catalyzed by a number of essential proteins (named Fts) that assemble into a ring-like structure at the future division site. Several of these Fts proteins are intrinsic transmembrane proteins whose functions are largely unknown. Although these proteins appear to be recruited to the division site in a hierarchical order, the molecular interactions underlying the assembly of the cell division machinery remain mostly unspecified. In the prese...

  8. Evolutionary Cell Biology of Division Mode in the Bacterial Planctomycetes-Verrucomicrobia- Chlamydiae Superphylum

    Science.gov (United States)

    Rivas-Marín, Elena; Canosa, Inés; Devos, Damien P.

    2016-01-01

    Bacteria from the Planctomycetes, Verrucomicrobia, and Chlamydiae (PVC) superphylum are exceptions to the otherwise dominant mode of division by binary fission, which is based on the interaction between the FtsZ protein and the peptidoglycan (PG) biosynthesis machinery. Some PVC bacteria are deprived of the FtsZ protein and were also thought to lack PG. How these bacteria divide is still one of the major mysteries of microbiology. The presence of PG has recently been revealed in Planctomycetes and Chlamydiae, and proteins related to PG synthesis have been shown to be implicated in the division process in Chlamydiae, providing important insights into PVC mechanisms of division. Here, we review the historical lack of observation of PG in PVC bacteria, its recent detection in two phyla and its involvement in chlamydial cell division. Based on the detection of PG-related proteins in PVC proteomes, we consider the possible evolution of the diverse division mechanisms in these bacteria. We conclude by summarizing what is known and what remains to be understood about the evolutionary cell biology of PVC division modes. PMID:28018303

  9. Evolutionary cell biology of division mode in the bacterial Planctomycetes-Verrucomicrobia-Chlamydiae superphylum

    Directory of Open Access Journals (Sweden)

    Elena Rivas-Marín

    2016-12-01

    Full Text Available Bacteria from the Planctomycetes, Verrucomicrobia and Chlamydiae (PVC superphylum are exceptions to the otherwise dominant mode of division by binary fission, which is based on the interaction between the FtsZ protein and the peptidoglycan (PG biosynthesis machinery. Some PVC bacteria are deprived of the FtsZ protein and were also thought to lack PG. How these bacteria divide is still one of the major mysteries of microbiology. The presence of PG has recently been revealed in Planctomycetes and Chlamydiae, and proteins related to PG synthesis have been shown to be implicated in the division process in Chlamydiae, providing important insights into PVC mechanisms of division. Here, we review the historical lack of observation of PG in PVC bacteria, its recent detection in two phyla and its involvement in chlamydial cell division. Based on the detection of PG-related proteins in PVC proteomes, we consider the possible evolution of the diverse division mechanisms in these bacteria. We conclude by summarizing what is known and what remains to be understood about the evolutionary cell biology of PVC division modes.

  10. Segmentation of White Blood Cells through Nucleus Mark Watershed Operations and Mean Shift Clustering

    Directory of Open Access Journals (Sweden)

    Zhi Liu

    2015-09-01

    Full Text Available This paper presents a novel method for segmentation of white blood cells (WBCs in peripheral blood and bone marrow images under different lights through mean shift clustering, color space conversion and nucleus mark watershed operation (NMWO. The proposed method focuses on obtaining seed points. First, color space transformation and image enhancement techniques are used to obtain nucleus groups as inside seeds. Second, mean shift clustering, selection of the C channel component in the CMYK model, and illumination intensity adjustment are employed to acquire WBCs as outside seeds. Third, the seeds and NMWO are employed to precisely determine WBCs and solve the cell adhesion problem. Morphological operations are further used to improve segmentation accuracy. Experimental results demonstrate that the algorithm exhibits higher segmentation accuracy and robustness compared with traditional methods.

  11. Cell Divisions Are Required for L1 Retrotransposition▿

    Science.gov (United States)

    Shi, Xi; Seluanov, Andrei; Gorbunova, Vera

    2007-01-01

    LINE-1 (L1) retrotransposons comprise a large fraction of genomic DNAs of many organisms. Many L1 elements are active and may generate potentially deleterious mutations by inserting into genes, yet little is known about the control of retrotransposition by the host. Here we examined whether retrotransposition depends on the cell cycle by using a retrotransposition assay with cultured human cells. We show that in both cancer cells and primary human fibroblasts, retrotransposition was strongly inhibited in the cells arrested in the G1, S, G2, or M stage of the cell cycle. Retrotransposition was also inhibited during cellular senescence in primary human fibroblasts. The levels of L1 transcripts were strongly reduced in arrested cells, suggesting that the reduction in L1 transcript abundance limits retrotransposition in nondividing cells. We hypothesize that inhibition of retrotransposition in nondividing cells protects somatic tissues from accumulation of deleterious mutations caused by L1 elements. PMID:17145770

  12. Stereotypical cell division orientation controls neural rod midline formation in zebrafish.

    Science.gov (United States)

    Quesada-Hernández, Elena; Caneparo, Luca; Schneider, Sylvia; Winkler, Sylke; Liebling, Michael; Fraser, Scott E; Heisenberg, Carl-Philipp

    2010-11-09

    The development of multicellular organisms is dependent on the tight coordination between tissue growth and morphogenesis. The stereotypical orientation of cell divisions has been proposed to be a fundamental mechanism by which proliferating and growing tissues take shape. However, the actual contribution of stereotypical division orientation (SDO) to tissue morphogenesis is unclear. In zebrafish, cell divisions with stereotypical orientation have been implicated in both body-axis elongation and neural rod formation, although there is little direct evidence for a critical function of SDO in either of these processes. Here we show that SDO is required for formation of the neural rod midline during neurulation but dispensable for elongation of the body axis during gastrulation. Our data indicate that SDO during both gastrulation and neurulation is dependent on the noncanonical Wnt receptor Frizzled 7 (Fz7) and that interfering with cell division orientation leads to severe defects in neural rod midline formation but not body-axis elongation. These findings suggest a novel function for Fz7-controlled cell division orientation in neural rod midline formation during neurulation.

  13. Cell cycle kinetics with supramitotic control, two cell types, and unequal division: a model of transformed embryonic cells.

    Science.gov (United States)

    Kimmel, M; Arino, O

    1991-06-01

    We develop a mathematical model of cell cycle kinetics of transformed embryonic cells. The model includes supramitotic regulation, in which decisions regarding growth control are made at a point inside the cell division cycle and their impact extends to the next decision point, located in the next division cycle. Another feature is the presence of two varieties of cells, which switch from one to the other with given transition probabilities. The third factor considered is unequal division of cells, also defined in probabilistic terms. We provide a rigorous description of the model and derivation of its equations and analyze its asymptotic properties by defining and investigating an abstract semigroup of positive linear operators in appropriate state space. The spectral properties of the semigroup yield the balanced exponential growth law for the model. To compare the model to experimental data, we derive basic pedigree statistics, beta curves, and generation time correlations. We present numerical calculations based on measurements available for the embryonic cells. We conclude that to yield the experimentally obtained pedigree statistics, switches from one cell variety to the other must be quite infrequent.

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

    NARCIS (Netherlands)

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

    2015-01-01

    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

  15. Polyimidazole conjugated oligonucleotides reach the nucleus of HeLa cells.

    Science.gov (United States)

    Morvan, F; Castex, C; Vivès, E; Imbach, J L

    2001-01-01

    Oligonucleotide models bearing 6, 12 or 18 histamine residues were synthesized on solid support and labeled with fluorescein. Only the oligo with 6 histamine residues showed a high uptake in HeLa cells with a nuclear localization. Experiment a 4 degrees C or with bafilomicyn A1 suggest that uptake proceeded by an endocytosis mechanism followed by a destabilization of the membrane. Once in the cytoplasm the oligo reached rapidly the nucleus.

  16. Scaling laws governing stochastic growth and division of single bacterial cells

    CERN Document Server

    Iyer-Biswas, Srividya; Henry, Jonathan T; Lo, Klevin; Burov, Stanislav; Lin, Yihan; Crooks, Gavin E; Crosson, Sean; Dinner, Aaron R; Scherer, Norbert F

    2014-01-01

    Uncovering the quantitative laws that govern the growth and division of single cells remains a major challenge. Using a unique combination of technologies that yields unprecedented statistical precision, we find that the sizes of individual Caulobacter crescentus cells increase exponentially in time. We also establish that they divide upon reaching a critical multiple ($\\approx$1.8) of their initial sizes, rather than an absolute size. We show that when the temperature is varied, the growth and division timescales scale proportionally with each other over the physiological temperature range. Strikingly, the cell-size and division-time distributions can both be rescaled by their mean values such that the condition-specific distributions collapse to universal curves. We account for these observations with a minimal stochastic model that is based on an autocatalytic cycle. It predicts the scalings, as well as specific functional forms for the universal curves. Our experimental and theoretical analysis reveals a ...

  17. Asymmetric cell division of granule neuron progenitors in the external granule layer of the mouse cerebellum

    Directory of Open Access Journals (Sweden)

    Parthiv Haldipur

    2015-07-01

    Full Text Available The plane of division of granule neuron progenitors (GNPs was analysed with respect to the pial surface in P0 to P14 cerebellum and the results showed that there was a significant bias towards the plane of cell division being parallel to pial surface across this developmental window. In addition, the distribution of β-Catenin in anaphase cells was analysed, which showed that there was a significant asymmetry in the distribution of β-Catenin in dividing GNPs. Further, inhibition of Sonic Hedgehog (Shh signalling had an effect on plane of cell division. Asymmetric distribution of β-Catenin was shown to occur towards the source of a localized extracellular cue.

  18. Label-free three-dimensional imaging of cell nucleus using third-harmonic generation microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Jian; Zheng, Wei; Wang, Zi; Huang, Zhiwei, E-mail: biehzw@nus.edu.sg [Optical Bioimaging Laboratory, Department of Biomedical Engineering, Faculty of Engineering, National University of Singapore, Singapore 117576 (Singapore)

    2014-09-08

    We report the implementation of the combined third-harmonic generation (THG) and two-photon excited fluorescence (TPEF) microscopy for label-free three-dimensional (3-D) imaging of cell nucleus morphological changes in liver tissue. THG imaging shows regular spherical shapes of normal hepatocytes nuclei with inner chromatin structures while revealing the condensation of chromatins and nuclear fragmentations in hepatocytes of diseased liver tissue. Colocalized THG and TPEF imaging provides complementary information of cell nuclei and cytoplasm in tissue. This work suggests that 3-D THG microscopy has the potential for quantitative analysis of nuclear morphology in cells at a submicron-resolution without the need for DNA staining.

  19. Asymmetric division of clonal muscle stem cells coordinates muscle regeneration in vivo.

    Science.gov (United States)

    Gurevich, David B; Nguyen, Phong Dang; Siegel, Ashley L; Ehrlich, Ophelia V; Sonntag, Carmen; Phan, Jennifer M N; Berger, Silke; Ratnayake, Dhanushika; Hersey, Lucy; Berger, Joachim; Verkade, Heather; Hall, Thomas E; Currie, Peter D

    2016-07-01

    Skeletal muscle is an example of a tissue that deploys a self-renewing stem cell, the satellite cell, to effect regeneration. Recent in vitro studies have highlighted a role for asymmetric divisions in renewing rare "immortal" stem cells and generating a clonal population of differentiation-competent myoblasts. However, this model currently lacks in vivo validation. We define a zebrafish muscle stem cell population analogous to the mammalian satellite cell and image the entire process of muscle regeneration from injury to fiber replacement in vivo. This analysis reveals complex interactions between satellite cells and both injured and uninjured fibers and provides in vivo evidence for the asymmetric division of satellite cells driving both self-renewal and regeneration via a clonally restricted progenitor pool.

  20. Asymmetric cell division of granule neuron progenitors in the external granule layer of the mouse cerebellum

    OpenAIRE

    Parthiv Haldipur; Iswariya Sivaprakasam; Vinod Periasamy; Subashika Govindan; Shyamala Mani

    2015-01-01

    ABSTRACT The plane of division of granule neuron progenitors (GNPs) was analysed with respect to the pial surface in P0 to P14 cerebellum and the results showed that there was a significant bias towards the plane of cell division being parallel to pial surface across this developmental window. In addition, the distribution of β-Catenin in anaphase cells was analysed, which showed that there was a significant asymmetry in the distribution of β-Catenin in dividing GNPs. Further, inhibition of S...

  1. Three-dimensional patterns of cell division and expansion throughout the development of Arabidopsis thaliana leaves.

    Science.gov (United States)

    Kalve, Shweta; Fotschki, Joanna; Beeckman, Tom; Vissenberg, Kris; Beemster, Gerrit T S

    2014-12-01

    Variations in size and shape of multicellular organs depend on spatio-temporal regulation of cell division and expansion. Here, cell division and expansion rates were quantified relative to the three spatial axes in the first leaf pair of Arabidopsis thaliana. The results show striking differences in expansion rates: the expansion rate in the petiole is higher than in the leaf blade; expansion rates in the lateral direction are higher than longitudinal rates between 5 and 10 days after stratification, but become equal at later stages of leaf blade development; and anticlinal expansion co-occurs with, but is an order of magnitude slower than periclinal expansion. Anticlinal expansion rates also differed greatly between tissues: the highest rates occurred in the spongy mesophyll and the lowest in the epidermis. Cell division rates were higher and continued for longer in the epidermis compared with the palisade mesophyll, causing a larger increase of palisade than epidermal cell area over the course of leaf development. The cellular dynamics underlying the effect of shading on petiole length and leaf thickness were then investigated. Low light reduced leaf expansion rates, which was partly compensated by increased duration of the growth phase. Inversely, shading enhanced expansion rates in the petiole, so that the blade to petiole ratio was reduced by 50%. Low light reduced leaf thickness by inhibiting anticlinal cell expansion rates. This effect on cell expansion was preceded by an effect on cell division, leading to one less layer of palisade cells. The two effects could be uncoupled by shifting plants to contrasting light conditions immediately after germination. This extended kinematic analysis maps the spatial and temporal heterogeneity of cell division and expansion, providing a framework for further research to understand the molecular regulatory mechanisms involved.

  2. Novel roles of plant RETINOBLASTOMA-RELATED (RBR) protein in cell proliferation and asymmetric cell division.

    Science.gov (United States)

    Desvoyes, Bénédicte; de Mendoza, Alex; Ruiz-Trillo, Iñaki; Gutierrez, Crisanto

    2014-06-01

    The retinoblastoma (Rb) protein was identified as a human tumour suppressor protein that controls various stages of cell proliferation through the interaction with members of the E2F family of transcription factors. It was originally thought to be specific to animals but plants contain homologues of Rb, called RETINOBLASTOMA-RELATED (RBR). In fact, the Rb-E2F module seems to be a very early acquisition of eukaryotes. The activity of RBR depends on phosphorylation of certain amino acid residues, which in most cases are well conserved between plant and animal proteins. In addition to its role in cell-cycle progression, RBR has been shown to participate in various cellular processes such as endoreplication, transcriptional regulation, chromatin remodelling, cell growth, stem cell biology, and differentiation. Here, we discuss the most recent advances to define the role of RBR in cell proliferation and asymmetric cell division. These and other reports clearly support the idea that RBR is used as a landing platform of a plethora of cellular proteins and complexes to control various aspects of cell physiology and plant development.

  3. Hoxb1b controls oriented cell division, cell shape and microtubule dynamics in neural tube morphogenesis.

    Science.gov (United States)

    Zigman, Mihaela; Laumann-Lipp, Nico; Titus, Tom; Postlethwait, John; Moens, Cecilia B

    2014-02-01

    Hox genes are classically ascribed to function in patterning the anterior-posterior axis of bilaterian animals; however, their role in directing molecular mechanisms underlying morphogenesis at the cellular level remains largely unstudied. We unveil a non-classical role for the zebrafish hoxb1b gene, which shares ancestral functions with mammalian Hoxa1, in controlling progenitor cell shape and oriented cell division during zebrafish anterior hindbrain neural tube morphogenesis. This is likely distinct from its role in cell fate acquisition and segment boundary formation. We show that, without affecting major components of apico-basal or planar cell polarity, Hoxb1b regulates mitotic spindle rotation during the oriented neural keel symmetric mitoses that are required for normal neural tube lumen formation in the zebrafish. This function correlates with a non-cell-autonomous requirement for Hoxb1b in regulating microtubule plus-end dynamics in progenitor cells in interphase. We propose that Hox genes can influence global tissue morphogenesis by control of microtubule dynamics in individual cells in vivo.

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

    Indian Academy of Sciences (India)

    Mani Arora; Arga Chandrashekar Anil; Karl Burgess; Jane Delany; Ehsan Mesbahi

    2015-12-01

    The prasinophytes (early diverging Chlorophyta), consisting of simple unicellular green algae, occupy a critical position at the base of the green algal tree of life, with some of its representatives viewed as the cell form most similar to the first green alga, the `ancestral green flagellate'. Relatively large-celled unicellular eukaryotic phytoflagellates (such as Tetraselmis and Scherffelia), traditionally placed in Prasinophyceae but now considered as members of Chlorodendrophyceae (core Chlorophyta), have retained some primitive characteristics of prasinophytes. These organisms share several ultrastructural features with the other core chlorophytes (Trebouxiophyceae, Ulvophyceae and Chlorophyceae). However, the role of Chlorodendrophycean algae as the evolutionary link between cellular individuality and cellular cooperation has been largely unstudied. Here, we show that clonal populations of a unicellular chlorophyte, Tetraselmis indica, consist of morphologically and ultrastructurally variant cells which arise through asymmetric cell division. These cells also differ in their physiological properties. The structural and physiological differences in the clonal cell population correlate to a certain extent with the longevity and function of cells.

  5. Endocytosis restricts Arabidopsis KNOLLE syntaxin to the cell division plane during late cytokinesis.

    Science.gov (United States)

    Boutté, Yohann; Frescatada-Rosa, Márcia; Men, Shuzhen; Chow, Cheung-Ming; Ebine, Kazuo; Gustavsson, Anna; Johansson, Lenore; Ueda, Takashi; Moore, Ian; Jürgens, Gerd; Grebe, Markus

    2010-02-03

    Cytokinesis represents the final stage of eukaryotic cell division during which the cytoplasm becomes partitioned between daughter cells. The process differs to some extent between animal and plant cells, but proteins of the syntaxin family mediate membrane fusion in the plane of cell division in diverse organisms. How syntaxin localization is kept in check remains elusive. Here, we report that localization of the Arabidopsis KNOLLE syntaxin in the plane of cell division is maintained by sterol-dependent endocytosis involving a clathrin- and DYNAMIN-RELATED PROTEIN1A-dependent mechanism. On genetic or pharmacological interference with endocytosis, KNOLLE mis-localizes to lateral plasma membranes after cell-plate fusion. Fluorescence-loss-in-photo-bleaching and fluorescence-recovery-after-photo-bleaching experiments reveal lateral diffusion of GFP-KNOLLE from the plane of division to lateral membranes. In an endocytosis-defective sterol biosynthesis mutant displaying lateral KNOLLE diffusion, KNOLLE secretory trafficking remains unaffected. Thus, restriction of lateral diffusion by endocytosis may serve to maintain specificity of syntaxin localization during late cytokinesis.

  6. 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 thaliana

  7. Transplantation of gene-modified nucleus pulposus cells reverses rabbit intervertebral disc degeneration

    Institute of Scientific and Technical Information of China (English)

    LIU Yong; LI Jian-min; HU You-gu

    2011-01-01

    Background Intervertebral disc degeneration is the main cause of low back pain. The purpose of this study was to explore potential methods for reversing the degeneration of lumbar intervertebral discs by transplantation of gene-modified nucleus pulposus cells into rabbit degenerative lumbar intervertebral discs after transfecting rabbit nucleus pulposus cells with adeno-associated virus 2 (AAV2)-mediated connective tissue growth factor (CTGF) and tissue inhibitor of metalloproteinases 1 (TIMP1) genes in vitro.Methods Computer tomography (CT)-guided percutaneous annulus fibrosus injury was performed to build degenerative lumbar intervertebral disc models in 60 New Zealand white rabbits. rAAV2-CTGF-IRES-TIMP1-transfected rabbit nucleus pulposus cells were transplanted into degenerative lumbar intervertebral discs (transplantation group),phosphate-buffered saline (PBS) was injected into degenerative lumbar intervertebral discs (degeneration control group)and normal lumbar intervertebral discs served as a blank control group. After 6, 10 and 14 weeks, the disc height index (DHI) and signal intensity in intervertebral discs were observed by X-ray and magnetic resonance imaging (MRI) analysis.The expression of CTGF and TIMP1 in nucleus pulposus tissue was determined by Western blotting analysis, the synthesis efficiency of proteoglycan was determined by a 35S-sulfate incorporation assay, and the mRNA expression of type Ⅱ collagen and proteoglycan was detected by RT-PCR.Results MRI confirmed that degenerative intervertebral discs appeared two weeks after percutaneous puncture.Transgenic nucleus pulposus cell transplantation could retard the rapid deterioration of the DHI. MRI indicated that degenerative intervertebral discs were relieved in the transplantation group compared with the degeneration control group. The expression of collagen Ⅱ mRNA and proteoglycan mRNA was significantly higher in the transplantation group and the blank control group compared with the

  8. A NAD-dependent glutamate dehydrogenase coordinates metabolism with cell division in Caulobacter crescentus.

    Science.gov (United States)

    Beaufay, François; Coppine, Jérôme; Mayard, Aurélie; Laloux, Géraldine; De Bolle, Xavier; Hallez, Régis

    2015-07-01

    Coupling cell cycle with nutrient availability is a crucial process for all living cells. But how bacteria control cell division according to metabolic supplies remains poorly understood. Here, we describe a molecular mechanism that coordinates central metabolism with cell division in the α-proteobacterium Caulobacter crescentus. This mechanism involves the NAD-dependent glutamate dehydrogenase GdhZ and the oxidoreductase-like KidO. While enzymatically active GdhZ directly interferes with FtsZ polymerization by stimulating its GTPase activity, KidO bound to NADH destabilizes lateral interactions between FtsZ protofilaments. Both GdhZ and KidO share the same regulatory network to concomitantly stimulate the rapid disassembly of the Z-ring, necessary for the subsequent release of progeny cells. Thus, this mechanism illustrates how proteins initially dedicated to metabolism coordinate cell cycle progression with nutrient availability.

  9. Lipid spirals in Bacillus subtilis and their role in cell division.

    Science.gov (United States)

    Barák, Imrich; Muchová, Katarína; Wilkinson, Anthony J; O'Toole, Peter J; Pavlendová, Nada

    2008-06-01

    The fluid mosaic model of membrane structure has been revised in recent years as it has become evident that domains of different lipid composition are present in eukaryotic and prokaryotic cells. Using membrane binding fluorescent dyes, we demonstrate the presence of lipid spirals extending along the long axis of cells of the rod-shaped bacterium Bacillus subtilis. These spiral structures are absent from cells in which the synthesis of phosphatidylglycerol is disrupted, suggesting an enrichment in anionic phospholipids. Green fluorescent protein fusions of the cell division protein MinD also form spiral structures and these were shown by fluorescence resonance energy transfer to be coincident with the lipid spirals. These data indicate a higher level of membrane lipid organization than previously observed and a primary role for lipid spirals in determining the site of cell division in bacterial cells.

  10. Division genes in Escherichia coli are expressed coordinately to cell septum requirements by gearbox promoters.

    Science.gov (United States)

    Aldea, M; Garrido, T; Pla, J; Vicente, M

    1990-11-01

    The cell division ftsQAZ cluster and the ftsZ-dependent bolA morphogene of Escherichia coli are found to be driven by gearboxes, a distinct class of promoters characterized by showing an activity that is inversely dependent on growth rate. These promoters contain specific sequences upstream from the mRNA start point, and their -10 region is essential for the inverse growth rate dependence. Gearbox promoters are essential for driving ftsQAZ and bolA gene expression so that the encoded products are synthesized at constant amounts per cell independently of cell size. This mode of regulation would be expected for the expression of proteins that either play a regulatory role in cell division or form a stoichiometric component of the septum, a structure that, independently of cell size and growth rate, is produced once per cell cycle.

  11. Coordination between chromosome replication, segregation, and cell division in Caulobacter crescentus

    DEFF Research Database (Denmark)

    Jensen, Rasmus Bugge

    2006-01-01

    , and the completely replicated terminus regions stay associated with each other after chromosome replication is completed, disassociating very late in the cell cycle shortly before the final cell division event. Invagination of the cytoplasmic membrane occurs earlier than separation of the replicated terminus regions...... and formation of separate nucleoids, which results in trapping of a chromosome on either side of the cell division septum, indicating that there is not a nucleoid exclusion phenotype.......Progression through the Caulobacter crescentus cell cycle is coupled to a cellular differentiation program. The swarmer cell is replicationally quiescent, and DNA replication initiates at the swarmer-to-stalked cell transition. There is a very short delay between initiation of DNA replication...

  12. 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.

  13. ER-mitochondria contacts couple mtDNA synthesis with mitochondrial division in human cells.

    Science.gov (United States)

    Lewis, Samantha C; Uchiyama, Lauren F; Nunnari, Jodi

    2016-07-15

    Mitochondrial DNA (mtDNA) encodes RNAs and proteins critical for cell function. In human cells, hundreds to thousands of mtDNA copies are replicated asynchronously, packaged into protein-DNA nucleoids, and distributed within a dynamic mitochondrial network. The mechanisms that govern how nucleoids are chosen for replication and distribution are not understood. Mitochondrial distribution depends on division, which occurs at endoplasmic reticulum (ER)-mitochondria contact sites. These sites were spatially linked to a subset of nucleoids selectively marked by mtDNA polymerase and engaged in mtDNA synthesis--events that occurred upstream of mitochondrial constriction and division machine assembly. Our data suggest that ER tubules proximal to nucleoids are necessary but not sufficient for mtDNA synthesis. Thus, ER-mitochondria contacts coordinate licensing of mtDNA synthesis with division to distribute newly replicated nucleoids to daughter mitochondria.

  14. Bacillus thuringiensis peptidoglycan hydrolase SleB171 involved in daughter cell separation during cell division.

    Science.gov (United States)

    Li, Hua; Hu, Penggao; Zhao, Xiuyun; Yu, Ziniu; Li, Lin

    2016-04-01

    Whole-genome analyses have revealed a putative cell wall hydrolase gene (sleB171) that constitutes an operon with two other genes (ypeBandyhcN) of unknown function inBacillus thuringiensisBMB171. The putative SleB171 protein consists of 259 amino acids and has a molecular weight of 28.3 kDa. Gene disruption ofsleB171in the BMB171 genome causes the formation of long cell chains during the vegetative growth phase and delays spore formation and spore release, although it has no significant effect on cell growth and the ultimate release of the spores. The inseparable vegetative cells were nearly restored through the complementation ofsleB171expression. Real-time quantitative polymerase chain reaction analysis revealed thatsleB171is mainly active in the vegetative growth phase, with a maximum activity at the early stationary growth phase. Western blot analysis also confirmed thatsleB171is preferentially expressed during the vegetative growth phase. These results demonstrated that SleB171 plays an essential role in the daughter cell separation during cell division.

  15. Intrinsic characteristics of Min proteins on the cell division of Helicobacter pylori.

    Science.gov (United States)

    Nishida, Yoshie; Takeuchi, Hiroaki; Morimoto, Norihito; Umeda, Akiko; Kadota, Yoshu; Kira, Mizuki; Okazaki, Ami; Matsumura, Yoshihisa; Sugiura, Tetsuro

    2016-03-01

    Helicobacter pylori divides in the human stomach resulting in persistent infections and causing various disorders. Bacterial cell division is precisely coordinated by many molecules, including FtsZ and Min proteins. However, the role of Min proteins in H. pylori division is poorly understood. We investigated the functional characteristics of Min proteins in wild-type HPK5 and five HPK5-derivative mutants using morphological and genetic approaches. All mutants showed a filamentous shape. However, the bacterial cell growth and viability of three single-gene mutants (minC, minD, minE) were similar to that of the wild-type. The coccoid form number was lowest in the minE-disruptant, indicating that MinE contributes to the coccoid form conversion during the stationary phase. Immunofluorescence microscopic observations showed that FtsZ was dispersedly distributed throughout the bacterial cell irrespective of nucleoid position in only minD-disruptants, indicating that MinD is involved in the nucleoid occlusion system. A chase assay demonstrated that MinC loss suppressed FtsZ-degradation, indicating that FtsZ degrades in a MinC-dependent manner. Molecular interactions between FtsZ and Min proteins were confirmed by immunoprecipitation (IP)-western blotting (WB), suggesting the functional cooperation of these molecules during bacterial cell division. This study describes the intrinsic characteristics of Min proteins and provides new insights into H. pylori cell division.

  16. A new role of Klumpfuss in establishing cell fate during the GMC asymmetric cell division.

    Science.gov (United States)

    Gabilondo, Hugo; Losada-Pérez, María; Monedero, Ignacio; Torres-Herráez, Arturo; Molina, Isabel; Torroja, Laura; Benito-Sipos, Jonathan

    2014-11-01

    Studies in the Drosophila embryonic NB4-2 lineage have suggested that the transcription factor Klumpfuss (Klu) functions within embryonic neuroblast lineages to differentiate between the identities of two adjacent ganglion mother cells (GMCs). However, because of the limited lineage markers available, these observations have been made only for the NB4-2 lineage. Recent findings have placed this transcription factor in the vanguard of Drosophila neural stem cell biology by demonstrating that Klu is necessary for larval neuroblast growth and self-renewal. Here, we have studied the role of klu in an incipient model in order to address basic mechanisms of neural specification: the Va system. None of the previously reported roles of Klu satisfactorily explain our observations. Unexpectedly, in this lineage, klu is necessary for differentiating between the fates of the two neurons born from a unique GMC; klu mutants produce two B-type cells, rather than one B-type (Notch-OFF) and one A-type (Notch-ON) cell. Additionally, our results demonstrate that Klu operates in the GMC and/or in the newly born neuron, but not in the neuroblast. Unlike in larval neuroblasts in which Klu is an executor of Notch signaling, we have found that Klu does not lie downstream of the Notch pathway in this cell division context.

  17. SEPT9_v1 Functions in Breast Cancer Cell Division

    Science.gov (United States)

    2012-01-01

    from FCF- and DMSO-treated (50 M; 8 h) MDCK cells stained for CENP-E, CREST and DNA (DAPI). Arrows point to misaligned chromosomes; arrowheads point...for recombi - nant proteins, and Dr. Linda Wordeman (University of Washington) for HeLa cells expressing -tubulin-GFP.We also thank Nafisa Ghori for...needle concentration) sera were dialyzed, concentrated on Microcon 50.000 MW columns (Millipore), mixed with plasmid DNA in 10 mM Hepes, 140 mM KCl, pH

  18. 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

  19. Deletion of cdvB paralogous genes of Sulfolobus acidocaldarius impairs cell division

    NARCIS (Netherlands)

    Yang, Nuan; Driessen, Arnold J.M.

    2014-01-01

    The majority of Crenarchaeota utilize the cell division system (Cdv) to divide. This system consists of three highly conserved genes, cdvA, cdvB and cdvC that are organized in an operon. CdvC is homologous to the AAA-type ATPase Vps4, involved in multivesicular body biogenesis in eukaryotes. CdvA is

  20. Coordination of peptidoglycan synthesis and outer membrane constriction during Escherichia coli cell division

    NARCIS (Netherlands)

    Gray, A.N.; Egan, A.J.F.; van 't Veer, I.L.; Verheul, J.; Colavin, A.; Koumoutsi, A.; Biboy, J.; Altelaar, A.F.M.; Damen, M.J.; Huang, K.C.; Simorre, J.P.; Breukink, E.; den Blaauwen, T.; Typas, A.; Gross, C.A.; Vollmer, W.

    2015-01-01

    To maintain cellular structure and integrity during division, Gram-negative bacteria must carefully coordinate constriction of a tripartite cell envelope of inner membrane, peptidoglycan (PG), and outer membrane (OM). It has remained enigmatic how this is accomplished. Here, we show that envelope ma

  1. Direct interactions of early and late assembling division proteins in Escherichia coli cells resolved by FRET

    NARCIS (Netherlands)

    Alexeeva, S.; Gadella (jr.), T.W.J.; Verheul, J.; Verhoeven, G.S.; den Blaauwen, T.

    2010-01-01

    The bacterial cell division machinery is organized in the so-called divisome composed of highly dynamic but low abundant interacting (membrane-bound) proteins. In order to elucidate the molecular interactions between these proteins, we developed a robust background-insensitive quantitative spectral

  2. A pseudokinase couples signaling pathways to enable asymmetric cell division in a bacterium

    Directory of Open Access Journals (Sweden)

    W. Seth Childers

    2014-12-01

    Full Text Available Bacteria face complex decisions when initiating developmental events such as sporulation, nodulation, virulence, and asymmetric cell division. These developmental decisions require global changes in genomic readout, and bacteria typically employ intricate (yet poorly understood signaling networks that enable changes in cell function. The bacterium Caulobacter crescentus divides asymmetrically to yield two functionally distinct cells: a motile, chemotactic swarmer cell, and a sessile stalked cell with replication and division capabilities. Work from several Caulobacter labs has revealed that differentiation requires concerted regulation by several two-component system (TCS signaling pathways that are differentially positioned at the poles of the predivisional cell (Figure 1. The strict unidirectional flow from histidine kinase (HK to the response regulator (RR, observed in most studied TCS, is difficult to reconcile with the notion that information can be transmitted between two or more TCS signaling pathways. In this study, we uncovered a mechanism by which daughter cell fate, which is specified by the DivJ-DivK-PleC system and effectively encoded in the phosphorylation state of the single-domain RR DivK, is communicated to the CckA-ChpT-CtrA signaling pathway that regulates more than 100 genes for polar differentiation, replication initiation and cell division. Using structural biology and biochemical findings we proposed a mechanistic basis for TCS pathway coupling in which the DivL pseudokinase is repurposed as a sensor rather than participant in phosphotransduction.

  3. Control of the meiotic cell division program in plants

    NARCIS (Netherlands)

    Wijnker, T.G.; Schnittger, A.

    2013-01-01

    While the question of why organisms reproduce sexually is still a matter of controversy, it is clear that the foundation of sexual reproduction is the formation of gametes with half the genomic DNA content of a somatic cell. This reduction in genomic content is accomplished through meiosis that, in

  4. Structural and functional classes of multipolar cells in the ventral cochlear nucleus.

    Science.gov (United States)

    Doucet, John R; Ryugo, David K

    2006-04-01

    Multipolar cells in the ventral cochlear nucleus (VCN) are a structurally and functionally diverse group of projection neurons. Understanding their role in the ascending pathway involves partitioning multipolar cells into distinct populations and determining where in the brain each sends its coded messages. In this study, we used retrograde labeling techniques in rats to identify multipolar neurons that project their axons to the ipsilateral dorsal cochlear nucleus (DCN), the contralateral CN, or both structures. Three rats received injections of biotinylated dextran amine in the ipsilateral DCN and diamidino yellow in the contralateral CN. Several radiate multipolar neurons (defined by their axonal projections to the ipsilateral DCN and their dendrites that traverse VCN isofrequency sheets) were double-labeled but over 70% were not. This result suggests two distinct populations: (1) radiate-commissural (RC) multipolar cells that project to the ipsilateral DCN and the contralateral CN, and (2) radiate multipolar cells that project exclusively (in this context) to the ipsilateral DCN. In a different group of animals, we retrogradely labeled multipolar neurons that project their axons to the contralateral CN and measured the size of their cell bodies. The mean size of this population (266 +/- 156 microm2) was significantly smaller than those of RC-multipolar cells (418 +/- 140 microm2). We conclude that the CN commissural pathway is composed of at least two components: (1) RC multipolar cells and (2) commissural multipolar cells that are small- and medium-sized neurons that project exclusively (in this context) to the contralateral CN. These results identify separate structural groups of multipolar cells that may correspond to physiological unit types described in the literature. They also provide protocols for isolating and studying different populations of multipolar cells to determine the neural mechanisms that govern their responses to sound.

  5. Building the perfect parasite: cell division in apicomplexa.

    Directory of Open Access Journals (Sweden)

    Boris Striepen

    2007-06-01

    Full Text Available Apicomplexans are pathogens responsible for malaria, toxoplasmosis, and crytposporidiosis in humans, and a wide range of livestock diseases. These unicellular eukaryotes are stealthy invaders, sheltering from the immune response in the cells of their hosts, while at the same time tapping into these cells as source of nutrients. The complexity and beauty of the structures formed during their intracellular development have made apicomplexans the darling of electron microscopists. Dramatic technological progress over the last decade has transformed apicomplexans into respectable genetic model organisms. Extensive genomic resources are now available for many apicomplexan species. At the same time, parasite transfection has enabled researchers to test the function of specific genes through reverse and forward genetic approaches with increasing sophistication. Transfection also introduced the use of fluorescent reporters, opening the field to dynamic real time microscopic observation. Parasite cell biologists have used these tools to take a fresh look at a classic problem: how do apicomplexans build the perfect invasion machine, the zoite, and how is this process fine-tuned to fit the specific niche of each pathogen in this ancient and very diverse group? This work has unearthed a treasure trove of novel structures and mechanisms that are the focus of this review.

  6. Partitioning and Exocytosis of Secretory Granules during Division of PC12 Cells

    Directory of Open Access Journals (Sweden)

    Nickolay Vassilev Bukoreshtliev

    2012-01-01

    Full Text Available The biogenesis, maturation, and exocytosis of secretory granules in interphase cells have been well documented, whereas the distribution and exocytosis of these hormone-storing organelles during cell division have received little attention. By combining ultrastructural analyses and time-lapse microscopy, we here show that, in dividing PC12 cells, the prominent peripheral localization of secretory granules is retained during prophase but clearly reduced during prometaphase, ending up with only few peripherally localized secretory granules in metaphase cells. During anaphase and telophase, secretory granules exhibited a pronounced movement towards the cell midzone and, evidently, their tracks colocalized with spindle microtubules. During cytokinesis, secretory granules were excluded from the midbody and accumulated at the bases of the intercellular bridge. Furthermore, by measuring exocytosis at the single granule level, we showed, that during all stages of cell division, secretory granules were competent for regulated exocytosis. In conclusion, our data shed new light on the complex molecular machinery of secretory granule redistribution during cell division, which facilitates their release from the F-actin-rich cortex and active transport along spindle microtubules.

  7. DipM, a new factor required for peptidoglycan remodelling during cell division in Caulobacter crescentus.

    Science.gov (United States)

    Möll, Andrea; Schlimpert, Susan; Briegel, Ariane; Jensen, Grant J; Thanbichler, Martin

    2010-07-01

    In bacteria, cytokinesis is dependent on lytic enzymes that facilitate remodelling of the cell wall during constriction. In this work, we identify a thus far uncharacterized periplasmic protein, DipM, that is required for cell division and polarity in Caulobacter crescentus. DipM is composed of four peptidoglycan binding (LysM) domains and a C-terminal lysostaphin-like (LytM) peptidase domain. It binds to isolated murein sacculi in vitro, and is recruited to the site of constriction through interaction with the cell division protein FtsN. Mutational analyses showed that the LysM domains are necessary and sufficient for localization of DipM, while its peptidase domain is essential for function. Consistent with a role in cell wall hydrolysis, DipM was found to interact with purified murein sacculi in vitro and to induce cell lysis upon overproduction. Its inactivation causes severe defects in outer membrane invagination, resulting in a significant delay between cytoplasmic compartmentalization and final separation of the daughter cells. Overall, these findings indicate that DipM is a periplasmic component of the C. crescentus divisome that facilitates remodelling of the peptidoglycan layer and, thus, coordinated constriction of the cell envelope during the division process.

  8. miR-430 regulates oriented cell division during neural tube development in zebrafish.

    Science.gov (United States)

    Takacs, Carter M; Giraldez, Antonio J

    2016-01-15

    MicroRNAs have emerged as critical regulators of gene expression. Originally shown to regulate developmental timing, microRNAs have since been implicated in a wide range of cellular functions including cell identity, migration and signaling. miRNA-430, the earliest expressed microRNA during zebrafish embryogenesis, is required to undergo morphogenesis and has previously been shown to regulate maternal mRNA clearance, Nodal signaling, and germ cell migration. The functions of miR-430 in brain morphogenesis, however, remain unclear. Herein we find that miR-430 instructs oriented cell divisions in the neural rod required for neural midline formation. Loss of miR-430 function results in mitotic spindle misorientation in the neural rod, failed neuroepithelial integration after cell division, and ectopic cell accumulation in the dorsal neural tube. We propose that miR-430, independently of canonical apicobasal and planar cell polarity (PCP) pathways, coordinates the stereotypical cell divisions that instruct neural tube morphogenesis.

  9. 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

    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......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...... damage. These results are important guidelines to the design and interpretation of experiments involving nanowire-based transfection and electrical characterization of living cells....

  10. Ion channels generating complex spikes in cartwheel cells of the dorsal cochlear nucleus.

    Science.gov (United States)

    Kim, Yuil; Trussell, Laurence O

    2007-02-01

    Cartwheel cells are glycinergic interneurons that modify somatosensory input to the dorsal cochlear nucleus. They are characterized by firing of mixtures of both simple and complex action potentials. To understand what ion channels determine the generation of these two types of spike waveforms, we recorded from cartwheel cells using the gramicidin perforated-patch technique in brain slices of mouse dorsal cochlear nucleus and applied channel-selective blockers. Complex spikes were distinguished by whether they arose directly from a negative membrane potential or later during a long depolarization. Ca(2+) channels and Ca(2+)-dependent K(+) channels were major determinants of complex spikes. Onset complex spikes required T-type and possibly R-type Ca(2+) channels and were shaped by BK and SK K(+) channels. Complex spikes arising later in a depolarization were dependent on P/Q- and L-type Ca(2+) channels as well as BK and SK channels. BK channels also contributed to fast repolarization of simple spikes. Simple spikes featured an afterdepolarization that is probably the trigger for complex spiking and is shaped by T/R-type Ca(2+) and SK channels. Fast spikes were dependent on Na(+) channels; a large persistent Na(+) current may provide a depolarizing drive for spontaneous activity in cartwheel cells. Thus the diverse electrical behavior of cartwheel cells is determined by the interaction of a wide variety of ion channels with a prominent role played by Ca(2+).

  11. Liquid Crystal Pre-Patterning for Cell Division

    Science.gov (United States)

    Hill, Nicholas; Mottram, Nigel; Lydon, John

    2005-11-01

    We are examining the hypothesis that the overall geometry of mitosis is determined by liquid-crystal pre-patterning of the cytoplasm. The identification of mitosis with liquid crystalline (LX) phases is at least 50 years old but no attempt has been made to propose a detailed theory, presumably because of the difficulties in applying a theory of liquid crystals (LCs) in a 3D geometry. In this work, we use a mathematical model (Q-tensor theory) of a nematic LC for the cytoplasm of the cell and solve this numerically to show that the geometry of the prophase and metaphase can be explained using LX phases. The pre-patterning for the spindle is regarded as a bipolar LX assembly with the centrosomes acting as LC poles (centres of LX defects). The centrosomes and the nuclear envelope are both treated as bodies submerged in the LC medium between two spherical shells (the nuclear and cell membranes). The geometries considered are novel and 3D.

  12. Thymosin Beta-4 Recombinant Adeno-associated Virus Enhances Human Nucleus Pulposus Cell Proliferation and Reduces Cell Apoptosis and Senescence

    Institute of Scientific and Technical Information of China (English)

    Yuan-Yi Wang; Qing-San Zhu; Yi-Wei Wang; Ruo-Feng Yin

    2015-01-01

    Background:Thymosin beta-4 (TB-4) is considered key roles in tissue development,maintenance and pathological processes.The study aimed to prove TB-4 positive biological function on nucleus pulposus (NP) cell apoptosis and slowing the process of cell aging while increasing the cell proliferation.Methods:TB-4 recombinant adeno-associated virus (AAV) was constructed and induced to human NP cells.Cell of same group were cultured without gene modification as controlled group.Proliferation capacity and cell apoptosis were observed during 6 passages of the cells.Morphology and expression of the TB-4 gene were documented as parameter of cell activity during cell passage.Results:NP cells with TB-4 transfection has normal TB-4 expression and exocytosis.NP cells with TB-4 transfection performed significantly higher cell activity than that at the control group in each generation.TB-4 recombinant AAV-transfected human NP cells also show slower cell aging,lower cell apoptosis and higher cell proliferation than control group.Conclusions:TB-4 can prevent NP cell apoptosis,slow NP cell aging and promote NP cell proliferation.AAV transfection technique was able to highly and stably express TB-4 in human NP cells,which may provide a new pathway for innovation in the treatment of intervertebral disc degenerative diseases.

  13. Haspin has Multiple Functions in the Plant Cell Division Regulatory Network.

    Science.gov (United States)

    Kozgunova, Elena; Suzuki, Takamasa; Ito, Masaki; Higashiyama, Tetsuya; Kurihara, Daisuke

    2016-04-01

    Progression of cell division is controlled by various mitotic kinases. In animal cells, phosphorylation of histone H3 at Thr3 by the kinase Haspin (haploid germ cell-specific nuclear protein kinase) promotes centromeric Aurora B localization to regulate chromosome segregation. However, less is known about the function of Haspin in regulatory networks in plant cells. Here, we show that inhibition of Haspin with 5-iodotubercidin (5-ITu) in Bright Yellow-2 (BY-2) cells delayed chromosome alignment. Haspin inhibition also prevented the centromeric localization of Aurora3 kinase (AUR3) and disrupted its function. This suggested that Haspin plays a role in the specific positioning of AUR3 on chromosomes in plant cells, a function conserved in animals. The results also indicated that Haspin and AUR3 are involved in the same pathway, which regulates chromosome alignment during prometaphase/metaphase. Remarkably, Haspin inhibition by 5-ITu also led to a severe cytokinesis defect, resulting in binuclear cells with a partially formed cell plate. The 5-ITu treatment did not affect microtubules, AUR1/2 or the NACK-PQR pathway; however, it did alter the distribution of actin filaments on the cell plate. Together, these results suggested that Haspin has several functions in regulating cell division in plant cells: in the localization of AUR3 on centromeres and in regulating late cell plate expansion during cytokinesis.

  14. Asymmetric B Cell Division%B细胞不对称分裂

    Institute of Scientific and Technical Information of China (English)

    王晓芳; 姜云瀚; 沈关心

    2012-01-01

    It has been mostly accepted that asymmetric cell division is important for cell diversi -ty. Asymmetric B cell division is firstly found in the study of antibody class switch . Recently, five American scientists have addressed the asymmetric division of B cells in germinal centre . The result has been published in the journal of Science (20 January 2012). Asymmetric B cell division is involved in antibody class switch and antibody affinity maturation of immunity . Although the mechanism of asymmetric B cell division remains unclear , the recent study implies that the molecules that display asymmetry distribution in the cell may play as upstream factors . Moreover, asymmetric B cell division and asymmetric segregation of antigen may have independent and synergistic actions in the process of antibody affinity maturation.%细胞的不对称分裂对于细胞多样性产生的重要性已经被大部分人所认识.B细胞的不对称分裂首先是在抗体类别转换的研究中发现的.最近,美国5科学家对B细胞在免疫发生中心中不对称分裂的原因进行了探索.结果 发表在2012年1月20日出版的中.B细胞的不对称分裂参与体液免疫的抗体类别转换和抗体亲和力成熟过程.对于其机制仍不清楚,但目前研究初步提示细胞内分子的不对称分布是其发生的上游因素.并且B细胞的不对称分裂可能与不对称抗原分离可能在抗体亲和力成熟过程中具有独立协同作用.

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

    Directory of Open Access Journals (Sweden)

    Stefania Castagnetti

    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.

  16. Folded genome as a platform for the functional compartmentalization of the eukaryotic cell nucleus

    Directory of Open Access Journals (Sweden)

    Ioudinkova E. S.

    2014-03-01

    Full Text Available In a number of recent studies a tight interconnection between the spatial organization of the eukaryotic genome and its functioning has been demonstrated. Moreover, it is becoming evident that the folded DNA by itself consti- tutes an important, if not the key, factor supporting the internal nuclear organization. In this review, we will discuss the current state of chromatin research with the special attention focused on chromosome territories, chromatin folding and dynamics, chromatin domains, transcription and replication factories. Based on this analysis we will show how interphase chromosomes define the assembly of different nuclear compartments and underlie the spatial compartmentalization of the cell nucleus.

  17. DNA lesions, inducible DNA repair, and cell division: Three key factors in mutagenesis and carcinogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Ames, B.N.; Shigenaga, M.K. [Univ. of California, Berkeley, CA (United States); Gold, L.S. [Lawrence Berkeley National Lab., CA (United States)

    1993-12-01

    DNA lesions that escape repair have a certain probability of giving rise to mutations when the cell divides. Endogenous DNA damage is high: 10{sup 6} oxidative lesions are present per rat cell. An exogenous mutagen produces an increment in lesions over the background rate of endogenous lesions. The effectiveness of a particular lesion depends on whether it is excised by a DNA repair system and the probability that it gives rise to a mutation when the cell divides. When the cell divides, an unrepaired DNA lesion has a certain probability of giving rise to a mutation. Thus, an important factor in the mutagenic effect of an exogenous agent whether it is genotoxic or non-genotoxic, is the increment it causes over the background cell division rate (mitogenesis) in cells that appear to matter most in cancer, the stem cells, which are not on their way to being discarded. Increasing their cell division rate increases by high doses of chemicals. If both the rate of DNA lesions and cell division are increased, then there will be a multiplicative effect on mutagenesis (and carcinogenesis), for example, by high doses of a mutagen that also increases mitogenesis through cell killing. The defense system against reactive electrophilic mutagens, such as the glutathione transferases, are also almost all inducible and buffer cells against increments in active forms of chemicals that can cause DNA lesions. A variety of DNA repair defense systems, almost all inducible, buffer the cell against any increment in DNA lesions. Therefore, the effect of a particular chemical insult depends on the level of each defense, which in turn depends on the past history of exposure. Exogenous agents can influence the induction and effectiveness of these defenses. Defenses can be partially disabled by lack of particular micronutrients in the diet (e.g., antioxidants).

  18. A polymerization–depolymerization model for generation of contractile force during bacterial cell division

    Indian Academy of Sciences (India)

    Biplab Ghosh; Anirban Sain

    2008-08-01

    During the last phase of cell division in bacteria, a polymeric ring forms at the division site. The ring, made of intracellular proteins, anchors to the cell wall and starts to contract. That initiates a dividing septum to close in, like the shutter of a camera, eventually guillotining the cell into two daughters. All through, the ring remains at the leading edge of the septum and seems to power its closure. It is not understood why does the ring contract. We propose a theoretical model to explain this. It is worth mentioning that a similar contraction phenomenon occurs for the actin ring in eukaryotes, but there it is due to motor proteins, which however, are absent in bacteria.

  19. Asymptotic behavior of a nonlinear functional-integral equation of cell kinetics with unequal division.

    Science.gov (United States)

    Arino, O; Kimmel, M

    1989-01-01

    A model of cell cycle kinetics is proposed, which includes unequal division of cells, and a nonlinear dependence of the fraction of cells re-entering proliferation on the total number of cells in the cycle. The model is described by a nonlinear functional-integral equation. It is analyzed using the operator semigroup theory combined with classical differential equations approach. A complete description of the asymptotic behavior of the model is provided for a relatively broad class of nonlinearities. The nonnegative solutions either tend to a stable steady state, or to zero. The simplicity of the model makes it an interesting step in the analysis of dynamics of nonlinear structure populations.

  20. Cell Division Mode Change Mediates the Regulation of Cerebellar Granule Neurogenesis Controlled by the Sonic Hedgehog Signaling

    Directory of Open Access Journals (Sweden)

    Rong Yang

    2015-11-01

    Full Text Available Symmetric and asymmetric divisions are important for self-renewal and differentiation of stem cells during neurogenesis. Although cerebellar granule neurogenesis is controlled by sonic hedgehog (SHH signaling, whether and how this process is mediated by regulation of cell division modes have not been determined. Here, using time-lapse imaging and cell culture from neuronal progenitor-specific and differentiated neuron-specific reporter mouse lines (Math1-GFP and Dcx-DsRed and Patched+/− mice in which SHH signaling is activated, we find evidence for the existence of symmetric and asymmetric divisions that are closely associated with progenitor proliferation and differentiation. While activation of the SHH pathway enhances symmetric progenitor cell divisions, blockade of the SHH pathway reverses the cell division mode change in Math1-GFP;Dcx-DsRed;Patched+/− mice by promoting asymmetric divisions or terminal neuronal symmetric divisions. Thus, cell division mode change mediates the regulation of cerebellar granule neurogenesis controlled by SHH signaling.

  1. A DNA damage checkpoint in Caulobacter crescentus inhibits cell division through a direct interaction with FtsW.

    Science.gov (United States)

    Modell, Joshua W; Hopkins, Alexander C; Laub, Michael T

    2011-06-15

    Following DNA damage, cells typically delay cell cycle progression and inhibit cell division until their chromosomes have been repaired. The bacterial checkpoint systems responsible for these DNA damage responses are incompletely understood. Here, we show that Caulobacter crescentus responds to DNA damage by coordinately inducing an SOS regulon and inhibiting the master regulator CtrA. Included in the SOS regulon is sidA (SOS-induced inhibitor of cell division A), a membrane protein of only 29 amino acids that helps to delay cell division following DNA damage, but is dispensable in undamaged cells. SidA is sufficient, when overproduced, to block cell division. However, unlike many other regulators of bacterial cell division, SidA does not directly disrupt the assembly or stability of the cytokinetic ring protein FtsZ, nor does it affect the recruitment of other components of the cell division machinery. Instead, we provide evidence that SidA inhibits division by binding directly to FtsW to prevent the final constriction of the cytokinetic ring.

  2. Cocaine exposure reorganizes cell type- and input-specific connectivity in the nucleus accumbens.

    Science.gov (United States)

    MacAskill, Andrew F; Cassel, John M; Carter, Adam G

    2014-09-01

    Repeated exposure to cocaine alters the structural and functional properties of medium spiny neurons (MSNs) in the nucleus accumbens (NAc). These changes suggest a rewiring of the NAc circuit, with an enhancement of excitatory synaptic connections onto MSNs. However, it is unknown how drug exposure alters the balance of long-range afferents onto different cell types in the NAc. Here we used whole-cell recordings, two-photon microscopy, optogenetics and pharmacogenetics to show how repeated cocaine exposure alters connectivity in the mouse NAc medial shell. Cocaine selectively enhanced amygdala innervation of MSNs expressing D1 dopamine receptors (D1-MSNs) relative to D2-MSNs. We also found that amygdala activity was required for cocaine-induced changes to behavior and connectivity. Finally, we established how heightened amygdala innervation can explain the structural and functional changes evoked by cocaine. Our findings reveal how exposure to drugs of abuse fundamentally reorganizes cell type- and input-specific connectivity in the NAc.

  3. SepG coordinates sporulation-specific cell division and nucleoid organization in Streptomyces coelicolor.

    Science.gov (United States)

    Zhang, Le; Willemse, Joost; Claessen, Dennis; van Wezel, Gilles P

    2016-04-01

    Bacterial cell division is a highly complex process that requires tight coordination between septum formation and chromosome replication and segregation. In bacteria that divide by binary fission a single septum is formed at mid-cell, a process that is coordinated by the conserved cell division scaffold protein FtsZ. In contrast, during sporulation-specific cell division in streptomycetes, up to a hundred rings of FtsZ (Z rings) are produced almost simultaneously, dividing the multinucleoid aerial hyphae into long chains of unigenomic spores. This involves the active recruitment of FtsZ by the SsgB protein, and at the same time requires sophisticated systems to regulate chromosome dynamics. Here, we show that SepG is required for the onset of sporulation and acts by ensuring that SsgB is localized to future septum sites. Förster resonance energy transfer imaging suggests direct interaction between SepG and SsgB. The beta-lactamase reporter system showed that SepG is a transmembrane protein with its central domain oriented towards the cytoplasm. Without SepG, SsgB fails to localize properly, consistent with a crucial role for SepG in the membrane localization of the SsgB-FtsZ complex. While SsgB remains associated with FtsZ, SepG re-localizes to the (pre)spore periphery. Expanded doughnut-shaped nucleoids are formed in sepG null mutants, suggesting that SepG is required for nucleoid compaction. Taken together, our work shows that SepG, encoded by one of the last genes in the conserved dcw cluster of cell division and cell-wall-related genes in Gram-positive bacteria whose function was still largely unresolved,coordinates septum synthesis and chromosome organization in Streptomyces.

  4. Primary immune system responders to nucleus pulposus cells: evidence for immune response in disc herniation

    Directory of Open Access Journals (Sweden)

    K Murai

    2010-01-01

    Full Text Available Although intervertebral disc herniation and associated sciatica is a common disease, its molecular pathogenesis is not well understood. Immune responses are thought to be involved. This study provides direct evidence that even non-degenerated nucleus pulposus (NP cells elicit immune responses. An in vitro colony forming inhibition assay demonstrated the suppressive effects of autologous spleen cells on NP cells and an in vitro cytotoxicity assay showed the positive cytotoxic effects of natural killer (NK cells and macrophages on NP cells. Non-degenerated rat NP tissues transplanted into wild type rats and immune-deficient mice demonstrated a significantly higher NP cell survival rate in immune-deficient mice. Immunohistochemical staining showed the presence of macrophages and NK cells in the transplanted NP tissues. These results suggest that even non-degenerated autologous NP cells are recognized by macrophages and NK cells, which may have an immunological function in the early phase of disc herniation. These findings contribute to understanding resorption and the inflammatory reaction to disc herniation.

  5. Modulating notochordal differentiation of human induced pluripotent stem cells using natural nucleus pulposus tissue matrix.

    Directory of Open Access Journals (Sweden)

    Yongxing Liu

    Full Text Available Human induced pluripotent stem cells (hiPSCs can differentiate into notochordal cell (NC-like cells when cultured in the presence of natural porcine nucleus pulposus (NP tissue matrix. The method promises massive production of high-quality, functional cells to treat degenerative intervertebral discs (IVDs. Based on our previous work, we further examined the effect of cell-NP matrix contact and culture medium on the differentiation, and further assessed the functional differentiation ability of the generated NC-like. The study showed that direct contact between hiPSCs and NP matrix can promote the differentiation yield, whilst both the contact and non-contact cultures can generate functional NC-like cells. The generated NC-like cells are highly homogenous regarding the expression of notochordal marker genes. A culture medium containing a cocktail of growth factors (FGF, EGF, VEGF and IGF-1 also supported the notochordal differentiation in the presence of NP matrix. The NC-like cells showed excellent functional differentiation ability to generate NP-like tissue which was rich in aggrecan and collagen type II; and particularly, the proteoglycan to collagen content ratio was as high as 12.5-17.5 which represents a phenotype close to NP rather than hyaline cartilage. Collectively, the present study confirmed the effectiveness and flexibility of using natural NP tissue matrix to direct notochordal differentiation of hiPSCs, and the potential of using the generated NC-like cells for treating IVD degeneration.

  6. Local Cell Death Changes the Orientation of Cell Division in the Developing Drosophila Wing Imaginal Disc Without Using Fat or Dachsous as Orienting Signals

    Science.gov (United States)

    Kale, Abhijit; Rimesso, Gerard; Baker, Nicholas E.

    2016-01-01

    Drosophila imaginal disc cells exhibit preferred cell division orientations according to location within the disc. These orientations are altered if cell death occurs within the epithelium, such as is caused by cell competition or by genotypes affecting cell survival. Both normal cell division orientations, and their orientations after cell death, depend on the Fat-Dachsous pathway of planar cell polarity (PCP). The hypothesis that cell death initiates a planar polarity signal was investigated. When clones homozygous for the pineapple eye (pie) mutation were made to initiate cell death, neither Dachsous nor Fat was required in pie cells for the re-orientation of nearby cells, indicating a distinct signal for this PCP pathway. Dpp and Wg were also not needed for pie clones to re-orient cell division. Cell shapes were evaluated in wild type and mosaic wing discs to assess mechanical consequences of cell loss. Although proximal wing disc cells and cells close to the dorso-ventral boundary were elongated in their preferred cell division axes in wild type discs, cell shapes in much of the wing pouch were symmetrical on average and did not predict their preferred division axis. Cells in pie mutant clones were slightly larger than their normal counterparts, consistent with mechanical stretching following cell loss, but no bias in cell shape was detected in the surrounding cells. These findings indicate that an unidentified signal influences PCP-dependent cell division orientation in imaginal discs. PMID:28030539

  7. Direct visualization of cell division using high-resolution imaging of M-phase of the cell cycle

    OpenAIRE

    Hesse, Michael; Raulf, Alexandra; Pilz, Gregor-Alexander; Haberlandt, Christian; Klein, Alexandra M; Jabs, Ronald; Zaehres, Holm; Fügemann, Christopher J.; Zimmermann, Katrin; Trebicka, Jonel; Welz, Armin; Pfeifer, Alexander; Röll, Wilhelm; Kotlikoff, Michael I.; Steinhäuser, Christian

    2012-01-01

    Current approaches to monitor and quantify cell division in live cells, and reliably distinguish between acytokinesis and endoreduplication, are limited and complicate determination of stem cell pool identities. Here we overcome these limitations by generating an in vivo reporter system using the scaffolding protein anillin fused to enhanced green fluorescent protein, to provide high spatiotemporal resolution of mitotic phase. This approach visualizes cytokinesis and midbody formation as hall...

  8. Mechanism of murine epidermal maintenance: Cell division and the Voter Model

    CERN Document Server

    Klein, Allon M; Jones, Philip H; Simons, Benjamin D

    2007-01-01

    This paper presents an interesting experimental example of voter-model statistics in biology. In recent work on mouse tail-skin, where proliferating cells are confined to a two-dimensional layer, we showed that cells proliferate and differentiate according to a simple stochastic model of cell division involving just one type of proliferating cell that may divide both symmetrically and asymmetrically. Curiously, these simple rules provide excellent predictions of the cell population dynamics without having to address their spatial distribution. Yet, if the spatial behaviour of cells is addressed by allowing cells to diffuse at random, one deduces that density fluctuations destroy tissue confluence, implying some hidden degree of spatial regulation in the physical system. To infer the mechanism of spatial regulation, we consider a two-dimensional model of cell fate that preserves the overall population dynamics. By identifying the resulting behaviour with a three-species variation of the "Voter" model, we predi...

  9. Deletion of cdvB paralogous genes of Sulfolobus acidocaldarius impairs cell division.

    Science.gov (United States)

    Yang, Nuan; Driessen, Arnold J M

    2014-03-01

    The majority of Crenarchaeota utilize the cell division system (Cdv) to divide. This system consists of three highly conserved genes, cdvA, cdvB and cdvC that are organized in an operon. CdvC is homologous to the AAA-type ATPase Vps4, involved in multivesicular body biogenesis in eukaryotes. CdvA is a unique archaeal protein that interacts with the membrane, while CdvB is homologous to the eukaryal Vps24 and forms helical filaments. Most Crenarcheota contain additional CdvB paralogs. In Sulfolobus acidocaldarius these are termed CdvB1-3. We have used a gene inactivation approach to determine the impact of these additional cdvB genes on cell division. Independent deletion mutants of these genes were analyzed for growth and protein localization. One of the deletion strains (ΔcdvB3) showed a severe growth defect on plates and delayed growth on liquid medium. It showed the formation of enlarged cells and a defect in DNA segregation. Since these defects are accompanied with an aberrant localization of CdvA and CdvB, we conclude that CdvB3 fulfills an important accessory role in cell division.

  10. Automatic detection of cell divisions (mitosis) in live-imaging microscopy images using Convolutional Neural Networks.

    Science.gov (United States)

    Shkolyar, Anat; Gefen, Amit; Benayahu, Dafna; Greenspan, Hayit

    2015-08-01

    We propose a semi-automated pipeline for the detection of possible cell divisions in live-imaging microscopy and the classification of these mitosis candidates using a Convolutional Neural Network (CNN). We use time-lapse images of NIH3T3 scratch assay cultures, extract patches around bright candidate regions that then undergo segmentation and binarization, followed by a classification of the binary patches into either containing or not containing cell division. The classification is performed by training a Convolutional Neural Network on a specially constructed database. We show strong results of AUC = 0.91 and F-score = 0.89, competitive with state-of-the-art methods in this field.

  11. Role of the Number of Microtubules in Chromosome Segregation during Cell Division

    CERN Document Server

    Bertalan, Zsolt; La Porta, Caterina A M; Zapperi, Stefano

    2015-01-01

    Faithful segregation of genetic material during cell division requires alignment of chromosomes between two spindle poles and attachment of their kinetochores to each of the poles. Failure of these complex dynamical processes leads to chromosomal instability (CIN), a characteristic feature of several diseases including cancer. While a multitude of biological factors regulating chromosome congression and bi-orientation have been identified, it is still unclear how they are integrated so that coherent chromosome motion emerges from a large collection of random and deterministic processes. Here we address this issue by a three dimensional computational model of motor-driven chromosome congression and bi-orientation during mitosis. Our model reveals that successful cell division requires control of the total number of microtubules: if this number is too small bi-orientation fails, while if it is too large not all the chromosomes are able to congress. The optimal number of microtubules predicted by our model compa...

  12. Visually guided whole cell patch clamp of mouse supraoptic nucleus neurons in cultured and acute conditions.

    Science.gov (United States)

    Stachniak, Tevye J E; Bourque, Charles W

    2006-07-01

    Recent advances in neuronal culturing techniques have supplied a new set of tools for studying neural tissue, providing effective means to study molecular aspects of regulatory elements in the supraoptic nucleus of the hypothalamus (SON). To combine molecular biology techniques with electrophysiological recording, we modified an organotypic culture protocol to permit transfection and whole cell patch-clamp recordings from SON cells. Neonatal mouse brain coronal sections containing the SON were dissected out, placed on a filter insert in culture medium, and incubated for at least 4 days to allow attachment to the insert. The SON was identifiable using gross anatomical landmarks, which remained intact throughout the culturing period. Immunohistochemical staining identified both vasopressinergic and oxytocinergic cells present in the cultures, typically appearing in well-defined clusters. Whole cell recordings from these cultures demonstrated that certain properties of the neonatal mouse SON were comparable to adult mouse magnocellular neurons. SON neurons in both neonatal cultures and acute adult slices showed similar sustained outward rectification above -60 mV and action potential broadening during evoked activity. Membrane potential, input resistance, and rapidly inactivating potassium current density (IA) were reduced in the cultures, whereas whole cell capacitance and spontaneous synaptic excitation were increased, perhaps reflecting developmental changes in cell physiology that warrant further study. The use of the outlined organotypic culturing procedures will allow the study of such electrophysiological properties of mouse SON using whole cell patch-clamp, in addition to various molecular, techniques that require longer incubation times.

  13. Direct interactions of early and late assembling division proteins in Escherichia coli cells resolved by FRET.

    Science.gov (United States)

    Alexeeva, Svetlana; Gadella, Theodorus W J; Verheul, Jolanda; Verhoeven, Gertjan S; den Blaauwen, Tanneke

    2010-07-01

    The bacterial cell division machinery is organized in the so-called divisome composed of highly dynamic but low abundant interacting (membrane-bound) proteins. In order to elucidate the molecular interactions between these proteins, we developed a robust background-insensitive quantitative spectral unmixing method for estimating FRET efficiencies at near endogenous protein levels using fluorescent protein fusions. The assembly of the division machinery of Escherichia coli occurs in two steps that are discrete in time: first the FtsZ-ring and the so-called early localizing proteins that together seem to prepare the division assembly at midcell. Subsequently, the late localizing protein complexes that contain the peptidoglycan-synthesizing proteins PBP1B and FtsI (PBP3) are recruited to the division site, which initiates septation. Physical interactions were observed between members within each group but also between the early and late localizing proteins strongly suggesting that these proteins despite their differential localization in time are linked at the molecular and functional level. Interestingly, we find FtsN, one of the latest proteins in the divisome assembly, interacting with late assembling proteins FtsI and FtsW, but also with early (proto-ring) protein ZapA. This is in line with the recently described role of FtsN in divisome stabilization including the proto-ring elements.

  14. The influence of GAP-43 on orientation of cell division through G proteins.

    Science.gov (United States)

    Huang, Rui; Zhao, Junpeng; Ju, Lili; Wen, Yujun; Xu, Qunyuan

    2015-12-01

    Recent studies have shown that GAP-43 is highly expressed in horizontally dividing neural progenitor cells, and G protein complex are required for proper mitotic-spindle orientation of those progenitors in the mammalian developing cortex. In order to verify the hypothesis that GAP-43 may influence the orientation of cell division through interacting with G proteins during neurogenesis, the GAP-43 RNA from adult C57 mouse was cloned into the pEGFP-N1 vector, which was then transfected into Madin-Darby Canine Kidney (MDCK) cells cultured in a three-dimensional (3D) cell culture system. The interaction of GAP-43 with Gαi was detected by co-immunoprecipitation (co-IP), while cystogenesis of 3D morphogenesis of MDCK cells and expression of GAP-43 and Gαi were determined by immunofluorescence and Western blotting. The results showed are as follows: After being transfected by pEGFP-N1-GAP-43, GAP-43 was localized on the cell membrane and co-localized with Gαi, and this dramatically induced a defective cystogenesis in 3D morphogenesis of MDCK cells. The functional interaction between GAP-43 and Gαi proteins was proven by the co-IP assay. It can be considered from the results that the GAP-43 is involved in the orientation of cell division by interacting with Gαi and this should be an important mechanism for neurogenesis in the mammalian brain.

  15. A quantitative study of the division cycle of Caulobacter crescentus stalked cells.

    Directory of Open Access Journals (Sweden)

    Shenghua Li

    2008-01-01

    Full Text Available Progression of a cell through the division cycle is tightly controlled at different steps to ensure the integrity of genome replication and partitioning to daughter cells. From published experimental evidence, we propose a molecular mechanism for control of the cell division cycle in Caulobacter crescentus. The mechanism, which is based on the synthesis and degradation of three "master regulator" proteins (CtrA, GcrA, and DnaA, is converted into a quantitative model, in order to study the temporal dynamics of these and other cell cycle proteins. The model accounts for important details of the physiology, biochemistry, and genetics of cell cycle control in stalked C. crescentus cell. It reproduces protein time courses in wild-type cells, mimics correctly the phenotypes of many mutant strains, and predicts the phenotypes of currently uncharacterized mutants. Since many of the proteins involved in regulating the cell cycle of C. crescentus are conserved among many genera of alpha-proteobacteria, the proposed mechanism may be applicable to other species of importance in agriculture and medicine.

  16. The development of fluorescence turn-on probe for Al(III) sensing and live cell nucleus-nucleoli staining

    Science.gov (United States)

    Saini, Anoop Kumar; Sharma, Vinay; Mathur, Pradeep; Shaikh, Mobin M.

    2016-01-01

    The morphology of nucleus and nucleolus is powerful indicator of physiological and pathological conditions. The specific staining of nucleolus recently gained much attention due to the limited and expensive availability of the only existing stain “SYTO RNA-Select”. Here, a new multifunctional salen type ligand (L1) and its Al3+ complex (1) are designed and synthesized. L1 acts as a chemosensor for Al3+ whereas 1 demonstrates specific staining of nucleus as well as nucleoli. The binding of 1 with nucleic acid is probed by DNase and RNase digestion in stained cells. 1 shows an excellent photostability, which is a limitation for existing nucleus stains during long term observations. 1 is assumed to be a potential candidate as an alternative to expensive commercial dyes for nucleus and nucleoli staining. PMID:27721431

  17. Divisome and segrosome components of Deinococcus radiodurans interact through cell division regulatory proteins.

    Science.gov (United States)

    Maurya, Ganesh K; Modi, Kruti; Misra, Hari S

    2016-08-01

    The Deinococcus radiodurans genome encodes many of the known components of divisome as well as four sets of genome partitioning proteins, ParA and ParB on its multipartite genome. Interdependent regulation of cell division and genome segregation is not understood. In vivo interactions of D. radiodurans' sdivisome, segrosome and other cell division regulatory proteins expressed on multicopy plasmids were studied in Escherichia coli using a bacterial two-hybrid system and confirmed by co-immunoprecipitation with the proteins made in E. coli. Many of these showed interactions both with the self and with other proteins. For example, DrFtsA, DrFtsZ, DrMinD, DrMinC, DrDivIVA and all four ParB proteins individually formed at least homodimers, while DrFtsA interacted with DrFtsZ, DrFtsW, DrFtsE, DrFtsK and DrMinD. DrMinD also showed interaction with DrFtsW, DrFtsE and DrMinC. Interestingly, septum site determining protein, DrDivIVA showed interactions with secondary genome ParAs as well as ParB1, ParB3 and ParB4 while DrMinC interacted with ParB1 and ParB3. PprA, a pleiotropic protein recently implicated in cell division regulation, neither interacted with divisome proteins nor ParBs but interacted at different levels with all four ParAs. These results suggest the formation of independent multiprotein complexes of 'DrFts' proteins, segrosome proteins and cell division regulatory proteins, and these complexes could interact with each other through DrMinC and DrDivIVA, and PprA in D. radiodurans.

  18. FtsZ and the division of prokaryotic cells and organelles.

    Science.gov (United States)

    Margolin, William

    2005-11-01

    Binary fission of many prokaryotes as well as some eukaryotic organelles depends on the FtsZ protein, which self-assembles into a membrane-associated ring structure early in the division process. FtsZ is homologous to tubulin, the building block of the microtubule cytoskeleton in eukaryotes. Recent advances in genomics and cell-imaging techniques have paved the way for the remarkable progress in our understanding of fission in bacteria and organelles.

  19. An interplay of migratory and division forces as a generic mechanism for stem cell patterns

    CERN Document Server

    Hannezo, Edouard; Joanny, Jean-François

    2015-01-01

    In many adult tissues, stem cells and differentiated cells are not homogeneously distributed : stem cells are arranged in periodic "niches", and differentiated cells are constantly produced and migrate out of these niches. In this article, we provide a general theoretical framework to study mixtures of dividing and actively migrating particles, which we apply to biological tissues. We show in particular that the interplay between the stresses arising from active cell migration and stem cell division give rise to robust stem cell patterns. The instability of the tissue leads to spatial patterns which are either steady or oscillating in time. The wavelength of the instability has an order of magnitude consistent with the biological observations. We also discuss the implications of these results for future in vitro and in vivo experiments.

  20. Machine learning classification of cell-specific cardiac enhancers uncovers developmental subnetworks regulating progenitor cell division and cell fate specification.

    Science.gov (United States)

    Ahmad, Shaad M; Busser, Brian W; Huang, Di; Cozart, Elizabeth J; Michaud, Sébastien; Zhu, Xianmin; Jeffries, Neal; Aboukhalil, Anton; Bulyk, Martha L; Ovcharenko, Ivan; Michelson, Alan M

    2014-02-01

    The Drosophila heart is composed of two distinct cell types, the contractile cardial cells (CCs) and the surrounding non-muscle pericardial cells (PCs), development of which is regulated by a network of conserved signaling molecules and transcription factors (TFs). Here, we used machine learning with array-based chromatin immunoprecipitation (ChIP) data and TF sequence motifs to computationally classify cell type-specific cardiac enhancers. Extensive testing of predicted enhancers at single-cell resolution revealed the added value of ChIP data for modeling cell type-specific activities. Furthermore, clustering the top-scoring classifier sequence features identified novel cardiac and cell type-specific regulatory motifs. For example, we found that the Myb motif learned by the classifier is crucial for CC activity, and the Myb TF acts in concert with two forkhead domain TFs and Polo kinase to regulate cardiac progenitor cell divisions. In addition, differential motif enrichment and cis-trans genetic studies revealed that the Notch signaling pathway TF Suppressor of Hairless [Su(H)] discriminates PC from CC enhancer activities. Collectively, these studies elucidate molecular pathways used in the regulatory decisions for proliferation and differentiation of cardiac progenitor cells, implicate Su(H) in regulating cell fate decisions of these progenitors, and document the utility of enhancer modeling in uncovering developmental regulatory subnetworks.

  1. Timing of Tissue-specific Cell Division Requires a Differential Onset of Zygotic Transcription during Metazoan Embryogenesis.

    Science.gov (United States)

    Wong, Ming-Kin; Guan, Daogang; Ng, Kaoru Hon Chun; Ho, Vincy Wing Sze; An, Xiaomeng; Li, Runsheng; Ren, Xiaoliang; Zhao, Zhongying

    2016-06-10

    Metazoan development demands not only precise cell fate differentiation but also accurate timing of cell division to ensure proper development. How cell divisions are temporally coordinated during development is poorly understood. Caenorhabditis elegans embryogenesis provides an excellent opportunity to study this coordination due to its invariant development and widespread division asynchronies. One of the most pronounced asynchronies is a significant delay of cell division in two endoderm progenitor cells, Ea and Ep, hereafter referred to as E2, relative to its cousins that mainly develop into mesoderm organs and tissues. To unravel the genetic control over the endoderm-specific E2 division timing, a total of 822 essential and conserved genes were knocked down using RNAi followed by quantification of cell cycle lengths using in toto imaging of C. elegans embryogenesis and automated lineage. Intriguingly, knockdown of numerous genes encoding the components of general transcription pathway or its regulatory factors leads to a significant reduction in the E2 cell cycle length but an increase in cell cycle length of the remaining cells, indicating a differential requirement of transcription for division timing between the two. Analysis of lineage-specific RNA-seq data demonstrates an earlier onset of transcription in endoderm than in other germ layers, the timing of which coincides with the birth of E2, supporting the notion that the endoderm-specific delay in E2 division timing demands robust zygotic transcription. The reduction in E2 cell cycle length is frequently associated with cell migration defect and gastrulation failure. The results suggest that a tissue-specific transcriptional activation is required to coordinate fate differentiation, division timing, and cell migration to ensure proper development.

  2. Cell Division Mode Change Mediates the Regulation of Cerebellar Granule Neurogenesis Controlled by the Sonic Hedgehog Signaling

    OpenAIRE

    Rong Yang; Minglei Wang; Jia Wang; Xingxu Huang; Ru Yang; Wei-Qiang Gao

    2015-01-01

    Summary Symmetric and asymmetric divisions are important for self-renewal and differentiation of stem cells during neurogenesis. Although cerebellar granule neurogenesis is controlled by sonic hedgehog (SHH) signaling, whether and how this process is mediated by regulation of cell division modes have not been determined. Here, using time-lapse imaging and cell culture from neuronal progenitor-specific and differentiated neuron-specific reporter mouse lines (Math1-GFP and Dcx-DsRed) and Patche...

  3. Role of eukaryotic-like serine/threonine kinases in bacterial cell division and morphogenesis.

    Science.gov (United States)

    Manuse, Sylvie; Fleurie, Aurore; Zucchini, Laure; Lesterlin, Christian; Grangeasse, Christophe

    2016-01-01

    Bacteria possess a repertoire of versatile protein kinases modulating diverse aspects of their physiology by phosphorylating proteins on various amino acids including histidine, cysteine, aspartic acid, arginine, serine, threonine and tyrosine. One class of membrane serine/threonine protein kinases possesses a catalytic domain sharing a common fold with eukaryotic protein kinases and an extracellular mosaic domain found in bacteria only, named PASTA for 'Penicillin binding proteins And Serine/Threonine kinase Associated'. Over the last decade, evidence has been accumulating that these protein kinases are involved in cell division, morphogenesis and developmental processes in Firmicutes and Actinobacteria. However, observations differ from one species to another suggesting that a general mechanism of activation of their kinase activity is unlikely and that species-specific regulation of cell division is at play. In this review, we survey the latest research on the structural aspects and the cellular functions of bacterial serine/threonine kinases with PASTA motifs to illustrate the diversity of the regulatory mechanisms controlling bacterial cell division and morphogenesis.

  4. Cumulative number of cell divisions as a meaningful timescale for adaptive laboratory evolution of Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Dae-Hee Lee

    Full Text Available Adaptive laboratory evolution (ALE under controlled conditions has become a valuable approach for the study of the genetic and biochemical basis for microbial adaptation under a given selection pressure. Conventionally, the timescale in ALE experiments has been set in terms of number of generations. As mutations are believed to occur primarily during cell division in growing cultures, the cumulative number of cell divisions (CCD would be an alternative way to set the timescale for ALE. Here we show that in short-term ALE (up to 40-50 days, Escherichia coli, under growth rate selection pressure, was found to undergo approximately 10(11.2 total cumulative cell divisions in the population to produce a new stable growth phenotype that results from 2 to 8 mutations. Continuous exposure to a low level of the mutagen N-methyl-N'-nitro-N-nitrosoguanidine was found to accelerate this timescale and led to a superior growth rate phenotype with a much larger number of mutations as determined with whole-genome sequencing. These results would be useful for the fundamental kinetics of the ALE process in designing ALE experiments and provide a basis for its quantitative description.

  5. Solanum lycopersicum AUXIN RESPONSE FACTOR 9 regulates cell division activity during early tomato fruit development

    Science.gov (United States)

    de Jong, Maaike; Wolters-Arts, Mieke; Schimmel, Bernardus C. J.; Stultiens, Catharina L. M.; de Groot, Peter F. M.; Powers, Stephen J.; Tikunov, Yury M.; Bovy, Arnoud G.; Mariani, Celestina; Vriezen, Wim H.; Rieu, Ivo

    2015-01-01

    The transformation of the ovary into a fruit after successful completion of pollination and fertilization has been associated with many changes at transcriptomic level. These changes are part of a dynamic and complex regulatory network that is controlled by phytohormones, with a major role for auxin. One of the auxin-related genes differentially expressed upon fruit set and early fruit development in tomato is Solanum lycopersicum AUXIN RESPONSE FACTOR 9 (SlARF9). Here, the functional analysis of this ARF is described. SlARF9 expression was found to be auxin-responsive and SlARF9 mRNA levels were high in the ovules, placenta, and pericarp of pollinated ovaries, but also in other plant tissues with high cell division activity, such as the axillary meristems and root meristems. Transgenic plants with increased SlARF9 mRNA levels formed fruits that were smaller than wild-type fruits because of reduced cell division activity, whereas transgenic lines in which SlARF9 mRNA levels were reduced showed the opposite phenotype. The expression analysis, together with the phenotype of the transgenic lines, suggests that, in tomato, ARF9 negatively controls cell division during early fruit development. PMID:25883382

  6. Polycystic kidney disease: cell division without a c(l)ue?

    Science.gov (United States)

    Simons, M; Walz, G

    2006-09-01

    Polycystic kidneys are caused by an amazingly broad array of genetic mutations and manipulations. The ciliary hypothesis has evolved as the unifying concept of cystogenesis: cilia, bend by fluid flow, initiate a calcium influx that prevents cyst formation. The integrity of ciliary functions has been linked to the polycystic kidney disease gene products localizing to the cilium or the basal body/centrosome. Until recently, the signals and cellular programs located downstream of the ciliary-mediated calcium flux have remained elusive. Now, several reports point towards a role of the cilium or the basal body/centrosome complex in planar cell polarity, a pathway that orients cell in the plane of a tissue layer. First, Inversin, a protein mutated in nephronophthisis type II was found to act as a switch between the canonical and the noncanonical Wnt cascade, suggesting that beta-catenin/TCF-dependent gene transcription has to be curtailed to allow normal tubular differentiation. Second, heterozygote deletions of Bardet-Biedl syndrome proteins affect neural tube closure and disrupt the cochlear sterociliary bundles, two typical planar cell polarity defects. Third, tubular epithelial cells undergo oriented cell division during tubular elongation, along the axis of the anterior-posterior axis of the nephron. Thus, the cilium or the basal body/centrosome complex may provide the spatial cues to position the centrosome and the mitotic spindle before the next cell division. Failure to communicate this spatial information may condemn the tubular epithelial cells to proliferate and to form cysts.

  7. Matrix stiffness determines the fate of nucleus pulposus-derived stem cells.

    Science.gov (United States)

    Navaro, Yosi; Bleich-Kimelman, Nadav; Hazanov, Lena; Mironi-Harpaz, Iris; Shachaf, Yonatan; Garty, Shai; Smith, Yoav; Pelled, Gadi; Gazit, Dan; Seliktar, Dror; Gazit, Zulma

    2015-05-01

    Intervertebral disc (IVD) degeneration and consequent low-back pain present a major medical challenge. Nucleus pulposus-derived stem cells (NP-SCs) may lead to a novel therapy for this severe disease. It was recently shown that survival and function of mature NP cells are regulated in part by tissue stiffness. We hypothesized that modification of matrix stiffness will influence the ability of cultured NP-SCs to proliferate, survive, and differentiate into mature NP cells. NP-SCs were subcultured in three-dimensional matrices of varying degrees of stiffness as measured by the material's shear storage modulus. Cell survival, activity, and rate of differentiation toward the chondrogenic or osteogenic lineage were analyzed. NP-SCs were found to proliferate and differentiate in all matrices, irrespective of matrix stiffness. However, matrices with a low shear storage modulus (G' = 1 kPa) promoted significantly more proliferation and chondrogenic differentiation, whereas matrices with a high modulus (G' = 2 kPa) promoted osteogenic differentiation. Imaging performed via confocal and scanning electron microscopes validated cell survival and highlighted stiffness-dependent cell-matrix interactions. These results underscore the effect of the matrix modulus on the fate of NP-SCs. This research may facilitate elucidation of the complex cross-talk between NP-SCs and their surrounding matrix in healthy as well as pathological conditions.

  8. Dynamic interaction between actin and nesprin2 maintain the cell nucleus in a prestressed state

    Science.gov (United States)

    Kumar, Abhishek; Shivashankar, G. V.

    2016-12-01

    Mechanical coupling between the nucleus and the cytoskeleton is indispensable for direct force transduction from the extra cellular matrix (ECM) to the chromatin. Although this physical coupling has been shown to be crucial for nuclear positioning and its function, the quantification of nuclear-cytoskeleton interaction has been lacking. In this paper, using various quantitative fluorescence spectroscopy techniques, we investigate the nature of this connection. High-resolution 3D imaging shows that nesprin2G forms short linear structures along actin stress fibers (ASFs) in the apical region of the nucleus. Fluorescence recovery after photobleaching (FRAP) revealed that the alignment of nesprin2G becomes heterogeneous when cell shape is engineered from elongated rectangular shape to square using micropatterned substrates. Further, fluorescence cross-correlation spectroscopy (FCCS) revealed that actin interacts transiently with outer nuclear membrane protein nesprin2G with a time scale of 12 ms. In addition, fluorescence resonance energy transfer (FRET) experiments show that the apical ASFs and nesprin2G are in close physical proximity. This interaction is spatially heterogeneous with high FRET along the ASFs. Lastly, we show that the disruption of actin to nuclear connection by over-expression of Dominant Negative Klarsicht, ANC-1, Syne Homology (DNKASH) leads to an increase in nuclear height. These results not only reveal the characteristics of actin-nesprin2G interaction and its significance in regulating nuclear morphology, but also validate the utility of quantitative fluorescence techniques in deciphering physical connections that are essential for mechanotransduction.

  9. Toxic effects of mercury on the cell nucleus of Dictyostelium discoideum.

    Science.gov (United States)

    Boatti, Lara; Rapallo, Fabio; Viarengo, Aldo; Marsano, Francesco

    2017-02-01

    Governmental agencies (www.epa.gov/mercury) and the scientific community have reported on the high toxicity due to mercury. Indeed, exposure to mercury can cause severe injury to the central nervous system and kidney in humans. Beyond its recognized toxicity, little is known regarding the molecular mechanisms involved in the actions of this heavy metal. Mercury has been also observed to form insoluble fibrous protein aggregates in the cell nucleus. We used D. discoideum to evaluate micronuclei formation and, since mercury is able to induce oxidative stress that could bring to protein aggregation, we assessed nuclear protein carbonylation by Western Blot. We observed a significant increase in micronuclei formation and 14 carbonylated proteins were identified. Moreover, we used isotope-coded protein label (ICPL) and mass spectrometry analysis of proteins obtained by lysis of purified nuclei, before of tryptic digestion to quantify nuclear proteins affected by mercury. In particular, we examined the effects of mercury that associate a classical genotoxic assay to proteomic effects into the nucleus. The data present direct evidences for mercury genotoxicity, nuclear protein carbonylation, quantitative change in core histones, and the involvement of pseudouridine synthase in mercury toxicity. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 417-425, 2017.

  10. Retinal ganglion cell projections to the hamster suprachiasmatic nucleus, intergeniculate leaflet, and visual midbrain: bifurcation and melanopsin immunoreactivity

    Science.gov (United States)

    Morin, Lawrence P.; Blanchard, Jane H.; Provencio, Ignacio

    2003-01-01

    The circadian clock in the suprachiasmatic nucleus (SCN) receives direct retinal input via the retinohypothalamic tract (RHT), and the retinal ganglion cells contributing to this projection may be specialized with respect to direct regulation of the circadian clock. However, some ganglion cells forming the RHT bifurcate, sending axon collaterals to the intergeniculate leaflet (IGL) through which light has secondary access to the circadian clock. The present studies provide a more extensive examination of ganglion cell bifurcation and evaluate whether ganglion cells projecting to several subcortical visual nuclei contain melanopsin, a putative ganglion cell photopigment. The results showed that retinal ganglion cells projecting to the SCN send collaterals to the IGL, olivary pretectal nucleus, and superior colliculus, among other places. Melanopsin-immunoreactive (IR) ganglion cells are present in the hamster retina, and some of these cells project to the SCN, IGL, olivary pretectal nucleus, or superior colliculus. Triple-label analysis showed that melanopsin-IR cells bifurcate and project bilaterally to each SCN, but not to the other visual nuclei evaluated. The melanopsin-IR cells have photoreceptive characteristics optimal for circadian rhythm regulation. However, the presence of moderately widespread bifurcation among ganglion cells projecting to the SCN, and projection by melanopsin-IR cells to locations distinct from the SCN and without known rhythm function, suggest that this ganglion cell type is generalized, rather than specialized, with respect to the conveyance of photic information to the brain. Copyright 2003 Wiley-Liss, Inc.

  11. EphB4 localises to the nucleus of prostate cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Mertens-Walker, Inga, E-mail: inga.mertenswalker@qut.edu.au [Institute of Health and Biomedical Innovation, Queensland University of Technology, Woolloongabba, QLD (Australia); Australian Prostate Cancer Research Centre—Queensland, Translational Research Institute, 37 Kent Street, Woolloongabba 4102, QLD (Australia); Lisle, Jessica E. [Institute of Health and Biomedical Innovation, Queensland University of Technology, Woolloongabba, QLD (Australia); Australian Prostate Cancer Research Centre—Queensland, Translational Research Institute, 37 Kent Street, Woolloongabba 4102, QLD (Australia); Nyberg, William A. [Institute of Health and Biomedical Innovation, Queensland University of Technology, Woolloongabba, QLD (Australia); Stephens, Carson R. [Institute of Health and Biomedical Innovation, Queensland University of Technology, Woolloongabba, QLD (Australia); Australian Prostate Cancer Research Centre—Queensland, Translational Research Institute, 37 Kent Street, Woolloongabba 4102, QLD (Australia); Burke, Leslie [Institute of Health and Biomedical Innovation, Queensland University of Technology, Woolloongabba, QLD (Australia); Rutkowski, Raphael; Herington, Adrian C.; Stephenson, Sally-Anne [Institute of Health and Biomedical Innovation, Queensland University of Technology, Woolloongabba, QLD (Australia); Australian Prostate Cancer Research Centre—Queensland, Translational Research Institute, 37 Kent Street, Woolloongabba 4102, QLD (Australia)

    2015-04-10

    The EphB4 receptor tyrosine kinase is over-expressed in a variety of different epithelial cancers including prostate where it has been shown to be involved in survival, migration and angiogenesis. We report here that EphB4 also resides in the nucleus of prostate cancer cell lines. We used in silico methods to identify a bipartite nuclear localisation signal (NLS) in the extracellular domain and a monopartite NLS sequence in the intracellular kinase domain of EphB4. To determine whether both putative NLS sequences were functional, fragments of the EphB4 sequence containing each NLS were cloned to create EphB4NLS-GFP fusion proteins. Localisation of both NLS-GFP proteins to the nuclei of transfected cells was observed, demonstrating that EphB4 contains two functional NLS sequences. Mutation of the key amino residues in both NLS sequences resulted in diminished nuclear accumulation. As nuclear translocation is often dependent on importins we confirmed that EphB4 and importin-α can interact. To assess if nuclear EphB4 could be implicated in gene regulatory functions potential EphB4-binding genomic loci were identified using chromatin immunoprecipitation and Lef1 was confirmed as a potential target of EphB4-mediated gene regulation. These novel findings add further complexity to the biology of this important cancer-associated receptor. - Highlights: • The EphB4 protein can be found in the nucleus of prostate cancer cell lines. • EphB4 contains two functional nuclear localisation signals. • Chromatin immunoprecipitation has identified potential genome sequences to which EphB4 binds. • Lef1 is a confirmed target for EphB4-mediated gene regulation.

  12. Increased expression of stefin B in the nucleus of T98G astrocytoma cells delays caspase activation

    Directory of Open Access Journals (Sweden)

    Tao eSun

    2012-09-01

    Full Text Available Stefin B (cystatin B is an endogenous inhibitor of cysteine proteinases localized in the nucleus and the cytosol. Loss-of-function mutations in the stefin B gene (CSTB gene were reported in patients with Unverricht-Lundborg disease (EPM1. Our previous results showed that thymocytes isolated from stefin B-deficient mice are more sensitive to apoptosis induced by the protein kinase C inhibitor staurosporin (STS than the wild-type control cells. We have also shown that the increased expression of stefin B in the nucleus of T98G astrocytoma cells delayed cell cycle progression through the S phase. In the present study we examined if the nuclear or cytosolic functions of stefin B are responsible for the accelerated induction of apoptosis observed in the cells from stefin B-deficient mice. We have shown that the overexpression of stefin B in the nucleus, but not in the cytosol of astrocytoma T98G cells, delayed caspase-3 and-7 activation. Pretreatment of cells with the pan-caspase inhibitor z-Val-Ala-Asp(OMe-fluoromethylketone completely inhibited caspase activation, while treatment with the inhibitor of calpains- and papain-like cathepsins (2S,3S-trans-epoxysuccinyl-leucylamido-3-methyl-butane ethyl ester did not prevent caspase activation. We concluded that the delay of caspase activation in T98G cells overexpressing stefin B in the nucleus is independent of cathepsin inhibition.

  13. Characterization of YmgF, a 72-residue inner membrane protein that associates with the Escherichia coli cell division machinery.

    Science.gov (United States)

    Karimova, Gouzel; Robichon, Carine; Ladant, Daniel

    2009-01-01

    Formation of the Escherichia coli division septum is catalyzed by a number of essential proteins (named Fts) that assemble into a ring-like structure at the future division site. Many of these Fts proteins are intrinsic transmembrane proteins whose functions are largely unknown. In the present study, we attempted to identify a novel putative component(s) of the E. coli cell division machinery by searching for proteins that could interact with known Fts proteins. To do that, we used a bacterial two-hybrid system based on interaction-mediated reconstitution of a cyclic AMP (cAMP) signaling cascade to perform a library screening in order to find putative partners of E. coli cell division protein FtsL. Here we report the characterization of YmgF, a 72-residue integral membrane protein of unknown function that was found to associate with many E. coli cell division proteins and to localize to the E. coli division septum in an FtsZ-, FtsA-, FtsQ-, and FtsN-dependent manner. Although YmgF was previously shown to be not essential for cell viability, we found that when overexpressed, YmgF was able to overcome the thermosensitive phenotype of the ftsQ1(Ts) mutation and restore its viability under low-osmolarity conditions. Our results suggest that YmgF might be a novel component of the E. coli cell division machinery.

  14. Endosymbiosis in trypanosomatid protozoa: the bacterium division is controlled during the host cell cycle

    Science.gov (United States)

    Catta-Preta, Carolina M. C.; Brum, Felipe L.; da Silva, Camila C.; Zuma, Aline A.; Elias, Maria C.; de Souza, Wanderley; Schenkman, Sergio; Motta, Maria Cristina M.

    2015-01-01

    Mutualism is defined as a beneficial relationship for the associated partners and usually assumes that the symbiont number is controlled. Some trypanosomatid protozoa co-evolve with a bacterial symbiont that divides in coordination with the host in a way that results in its equal distribution between daughter cells. The mechanism that controls this synchrony is largely unknown, and its comprehension might provide clues to understand how eukaryotic cells evolved when acquiring symbionts that later became organelles. Here, we approached this question by studying the effects of inhibitors that affect the host exclusively in two symbiont-bearing trypanosomatids, Strigomonas culicis and Angomonas deanei. We found that inhibiting host protein synthesis using cycloheximide or host DNA replication using aphidicolin did not affect the duplication of bacterial DNA. Although the bacteria had autonomy to duplicate their DNA when host protein synthesis was blocked by cycloheximide, they could not complete cytokinesis. Aphidicolin promoted the inhibition of the trypanosomatid cell cycle in the G1/S phase, leading to symbiont filamentation in S. culicis but not in A. deanei. Treatment with camptothecin blocked the host protozoa cell cycle in the G2 phase and induced the formation of filamentous symbionts in both species. Oryzalin, which affects host microtubule polymerization, blocked trypanosomatid mitosis and abrogated symbiont division. Our results indicate that host factors produced during the cell division cycle are essential for symbiont segregation and may control the bacterial cell number. PMID:26082757

  15. Directional Notch trafficking in Sara endosomes during asymmetric cell division in the spinal cord.

    Science.gov (United States)

    Kressmann, Sabine; Campos, Claudia; Castanon, Irinka; Fürthauer, Maximilian; González-Gaitán, Marcos

    2015-03-01

    Asymmetric division of neural precursor cells contributes to the generation of a variety of neuronal types. Asymmetric division is mediated by the asymmetric inheritance of fate determinants by the two daughter cells. In vertebrates, asymmetric fate determinants, such as Par3 and Mib, are only now starting to be identified. Here we show that, during mitosis of neural precursors in zebrafish, directional trafficking of Sara endosomes to one of the daughters can function as such a determinant. In asymmetric lineages, where one daughter cell becomes a neuron (n cell) whereas the other divides again to give rise to two neurons (p cell), we found that the daughter that inherits most of the Sara endosomes acquires the p fate. Sara endosomes carry an endocytosed pool of the Notch ligand DeltaD, which is thereby itself distributed asymmetrically. Sara and Notch are both essential for cell fate assignation within asymmetric lineages. Therefore, the Sara endosome system determines the fate decision between neuronal differentiation and mitosis in asymmetric lineages and thereby contributes to controlling the number of neural precursors and differentiated neurons during neurogenesis in a vertebrate.

  16. 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

  17. Transient, afferent input-dependent, postnatal niche for neural progenitor cells in the cochlear nucleus.

    Science.gov (United States)

    Volkenstein, Stefan; Oshima, Kazuo; Sinkkonen, Saku T; Corrales, C Eduardo; Most, Sam P; Chai, Renjie; Jan, Taha A; van Amerongen, Renée; Cheng, Alan G; Heller, Stefan

    2013-08-27

    In the cochlear nucleus (CN), the first central relay of the auditory pathway, the survival of neurons during the first weeks after birth depends on afferent innervation from the cochlea. Although input-dependent neuron survival has been extensively studied in the CN, neurogenesis has not been evaluated as a possible mechanism of postnatal plasticity. Here we show that new neurons are born in the CN during the critical period of postnatal plasticity. Coincidently, we found a population of neural progenitor cells that are controlled by a complex interplay of Wnt, Notch, and TGFβ/BMP signaling, in which low levels of TGFβ/BMP signaling are permissive for progenitor proliferation that is promoted by Wnt and Notch activation. We further show that cells with activated Wnt signaling reside in the CN and that these cells have high propensity for neurosphere formation. Cochlear ablation resulted in diminishment of progenitors and Wnt/β-catenin-active cells, suggesting that the neonatal CN maintains an afferent innervation-dependent population of progenitor cells that display active canonical Wnt signaling.

  18. Influence of recipient cytoplasm cell stage on transcription in bovine nucleus transfer embryos

    DEFF Research Database (Denmark)

    Smith, Steven D.; Soloy, Eva; Kanka, Jiri

    1996-01-01

    relies upon maternally derived RNA transcripts up to the 8-cell stage, at which time it begins to transcribe its own RNA. In this experiment, RNA synthesis was detected in nucleus transfer embryos (NTE) and control embryos by pulsing with 3H-uridine, fixation, and autoradiography on semithin sections...... of maturation. Control in-vitro-produced embryos were 3H-uridine-labelled and fixed at the 2-, 4-, early 8-, and late 8-cell stages. NTE were similarly prepared at 1, 3, and 20 hr postfusion and at the 2-, 4-, and 8-cell stages. In the control embryos, RNA synthesis was absent in the 2-, 4-, and early 8-cell...... stages, whereas in all late 8-cell stages, it was present. In NTE from nonactivated (MII phase) cytoplasts, there was a sharp decline in RNA synthesis at 1 hr and 3 hr after fusion and a total absence by 20 hr after fusion. In contrast, NTE from activated (S phase) cytoplasts exhibited continued high...

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

    Science.gov (United States)

    Kong, Xiangyi; Yang, Shuting; Gong, Fei; Lu, Changfu; Zhang, Shuoping; Lu, Guangxiu; Lin, Ge

    2016-01-01

    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 division behaviors. In NB embryos, the blastocyst formation rate increased with cell number from 7.4% (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.

  20. Glucosamine protects nucleus pulposus cells and induces autophagy via the mTOR-dependent pathway.

    Science.gov (United States)

    Jiang, LiBo; Jin, YongLong; Wang, HuiRen; Jiang, YunQi; Dong, Jian

    2014-11-01

    Although glucosamine has been suggested to be effective in the treatment of osteoarthritis, its effect on disc degeneration remains unclear. We sought to explore whether glucosamine can activate autophagy in rat nucleus pulposus (NP) cells and protect cells treated with IL-1β or hydrogen peroxide (H2 O2 ). Autophagy in cells was examined by detecting for LC3, Beclin-1, m-TOR, and p70S6K, as well as by analyzing autophagosomes. To inhibit autophagy, 3-methyladenine (3-MA) was used. In the cells treated with IL-1β, the levels of Adamts-4, Mmp-13, aggrecan, and Col2a1 were analyzed by real-time PCR and immunofluorescence. Apoptosis was analyzed by TUNEL. Cell senescence under H2 O2 was revealed by SA-β-Gal staining. Glucosamine could activate autophagy in a dose-dependent manner within 24 h and inhibit the phosphorylation of m-TOR and p70S6K. Autophagy in IL-1β or H2 O2 -treated cells was increased by glucosamine. Glucosamine attenuated the decrease of aggrecan and prevented the apoptosis of the NP cells induced by IL-1β, whereas 3-MA partly reversed these effects. The percentage of SA-β-Gal-positive cells induced by H2 O2 treatment was decreased by glucosamine, accompanied by the decline of p70S6K phosphorylation. Glucosamine protects NP cells and up-regulates autophagy by inhibiting the m-TOR pathway, which might point a potential therapeutic agent for disc degeneration.

  1. 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.

  2. An imaging flow cytometric method for measuring cell division history and molecular symmetry during mitosis.

    Science.gov (United States)

    Filby, Andrew; Perucha, Esperanza; Summers, Huw; Rees, Paul; Chana, Prabhjoat; Heck, Susanne; Lord, Graham M; Davies, Derek

    2011-07-01

    Asymmetric cell division is an important mechanism for generating cellular diversity, however, techniques for measuring the distribution of fate-regulating molecules during mitosis have been hampered by a lack of objectivity, quantitation, and statistical robustness. Here we describe a novel imaging flow cytometric approach that is able to report a cells proliferative history and cell cycle position using dye dilution, pH3, and PI staining to then measure the spatial distribution of fluorescent signals during mitosis using CCD-derived imagery. Using Jurkat cells, resolution of the fluorescently labeled populations was comparable to traditional PMT based cytometers thus eliminating the need to sort cells with specific division histories for microscopy. Subdividing mitotic stages by morphology allowed us to determine the time spent in each cell cycle phase using mathematical modeling approaches. Furthermore high sample throughput allowed us to collect statistically relevant numbers of cells without the need to use blocking agents that artificially enrich for mitotic events. The fluorescent imagery was used to measure PKCζ protein and EEA-1+ endosome distribution during different mitotic phases in Jurkat cells. While telophase cells represented the favorable population for measuring asymmetry, asynchronously dividing cells spent approximately 43 seconds in this stage, explaining why they were present at such low frequencies. This necessitated the acquisition of large cell numbers. Interestingly we found that PKCζ was inherited asymmetrically in 2.5% of all telophasic events whereas endosome inheritance was significantly more symmetrical. Furthermore, molecular polarity at early mitotic phases was a poor indicator of asymmetry during telophase highlighting that, though rare, telophasic events represented the best candidates for asymmetry studies. In summary, this technique combines the spatial information afforded by fluorescence microscopy with the statistical

  3. Location of chromosomes in the nucleus of human mesenchymal stem cells.

    Science.gov (United States)

    Lavrov, A V; Voldgorn, Y I

    2011-08-01

    For evaluation of the spatial structure of chromatin in nuclei of mesenchymal SC we determined the position of centromeres and individual chromosomes in interphase nucleus of mesenchymal SC. More than 300 nuclei in 7 cultures of mesenchymal SC were analyzed. Centromeres of chromosomes 6, 8, and 11 lie at a longer (0.68, 0.67, 0.7), while centromere of chromosome 18 at a shorter radial distance (0.49). Homologues of each chromosome had different radial distances. No differences in radial distances of centromeres were detected between mesenchymal SC from the adipose tissue and BM. After passage 8, distal displacement of chromosome 6 centromere (from 0.66 to 0.72) was observed, which probably indicates aging or spontaneous differentiation of cells.

  4. A Simulation-Based Study of Dorsal Cochlear Nucleus Pyramidal Cell Firing Patterns

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Daliri

    2012-02-01

    Full Text Available A two-variable integrate and fire model is presented to study the role of transient outward potassium currents in producing temporal aspects of dorsal cochlear nucleus (DCN pyramidal cells with different profiles namely the chopper, the pauser and the buildup. This conductance based model is a reduced version of KM-LIF model (Meng & Rinzel, 2010 which captures qualitative firing features of a detailed physiological model (Kanold & Manis, 2000.For our development we benefit from transient potassium currents properties i.e.fast activation and slow inactivation to generate long latency before start of firing.We compare our minimal model outputs in response to a hyperpolarizing stimulus fallowed by a depolarizing one with the data of KM-LIF model.The results conform well to the KM-LIF model with lower complexity.

  5. 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

    activity in the intestinal epithelium, where continued cell division takes place. Furthermore, mice haploinsufficient for both Cdc42 and Rab8a in the intestine demonstrated abnormal crypt morphogenesis and epithelial transporter physiology, further supporting their functional interaction. These data...

  6. Identification of genes that are essential to restrict genome duplication to once per cell division

    Science.gov (United States)

    Vassilev, Alex; Lee, Chrissie Y.; Vassilev, Boris; Zhu, Wenge; Ormanoglu, Pinar; Martin, Scott E.; DePamphilis, Melvin L.

    2016-01-01

    Nuclear genome duplication is normally restricted to once per cell division, but aberrant events that allow excess DNA replication (EDR) promote genomic instability and aneuploidy, both of which are characteristics of cancer development. Here we provide the first comprehensive identification of genes that are essential to restrict genome duplication to once per cell division. An siRNA library of 21,584 human genes was screened for those that prevent EDR in cancer cells with undetectable chromosomal instability. Candidates were validated by testing multiple siRNAs and chemical inhibitors on both TP53+ and TP53- cells to reveal the relevance of this ubiquitous tumor suppressor to preventing EDR, and in the presence of an apoptosis inhibitor to reveal the full extent of EDR. The results revealed 42 genes that prevented either DNA re-replication or unscheduled endoreplication. All of them participate in one or more of eight cell cycle events. Seventeen of them have not been identified previously in this capacity. Remarkably, 14 of the 42 genes have been shown to prevent aneuploidy in mice. Moreover, suppressing a gene that prevents EDR increased the ability of the chemotherapeutic drug Paclitaxel to induce EDR, suggesting new opportunities for synthetic lethalities in the treatment of human cancers. PMID:27144335

  7. Ubiquitin-mediated degradation of the formin mDia2 upon completion of cell division.

    Science.gov (United States)

    DeWard, Aaron D; Alberts, Arthur S

    2009-07-24

    Formins assemble non-branched actin filaments and modulate microtubule dynamics during cell migration and cell division. At the end of mitosis formins contribute to the generation of actin filaments that form the contractile ring. Rho small GTP-binding proteins activate mammalian diaphanous-related (mDia) formins by directly binding and disrupting an intramolecular autoinhibitory mechanism. Although the Rho-regulated activation mechanism is well characterized, little is known about how formins are switched off. Here we reveal a novel mechanism of formin regulation during cytokinesis based on the following observations; 1) mDia2 is degraded at the end of mitosis, 2) mDia2 is targeted for disposal by post-translational ubiquitin modification, 3) forced expression of activated mDia2 yields binucleate cells due to failed cytokinesis, and 4) the cytokinesis block is dependent upon mDia2-mediated actin assembly as versions of mDia2 incapable of nucleating actin but that still stabilize microtubules have no effect on cytokinesis. We propose that the tight control of mDia2 expression and ubiquitin-mediated degradation is essential for the completion of cell division. Because of the many roles for formins in cell morphology, we discuss the relevance of mDia protein turnover in other processes where ubiquitin-mediated proteolysis is an essential component.

  8. Translational repression determines a neuronal potential in Drosophila asymmetric cell division.

    Science.gov (United States)

    Okabe, M; Imai, T; Kurusu, M; Hiromi, Y; Okano, H

    2001-05-01

    Asymmetric cell division is a fundamental strategy for generating cellular diversity during animal development. Daughter cells manifest asymmetry in their differential gene expression. Transcriptional regulation of this process has been the focus of many studies, whereas cell-type-specific 'translational' regulation has been considered to have a more minor role. During sensory organ development in Drosophila, Notch signalling directs the asymmetry between neuronal and non-neuronal lineages, and a zinc-finger transcriptional repressor Tramtrack69 (TTK69) acts downstream of Notch as a determinant of non-neuronal identity. Here we show that repression of TTK69 protein expression in the neuronal lineage occurs translationally rather than transcriptionally. This translational repression is achieved by a direct interaction between cis-acting sequences in the 3' untranslated region of ttk69 messenger RNA and its trans-acting repressor, the RNA-binding protein Musashi (MSI). Although msi can act downstream of Notch, Notch signalling does not affect MSI expression. Thus, Notch signalling is likely to regulate MSI activity rather than its expression. Our results define cell-type-specific translational control of ttk69 by MSI as a downstream event of Notch signalling in asymmetric cell division.

  9. Brassinosteroid signaling directs formative cell divisions and protophloem differentiation in Arabidopsis root meristems.

    Science.gov (United States)

    Kang, Yeon Hee; Breda, Alice; Hardtke, Christian S

    2017-01-15

    Brassinosteroids (BRs) trigger an intracellular signaling cascade through its receptors BR INSENSITIVE 1 (BRI1), BRI1-LIKE 1 (BRL1) and BRL3. Recent studies suggest that BR-independent inputs related to vascular differentiation, for instance root protophloem development, modulate downstream BR signaling components. Here, we report that protophloem sieve element differentiation is indeed impaired in bri1 brl1 brl3 mutants, although this effect might not be mediated by canonical downstream BR signaling components. We also found that their small meristem size is entirely explained by reduced cell elongation, which is, however, accompanied by supernumerary formative cell divisions in the radial dimension. Thus, reduced cell expansion in conjunction with growth retardation, because of the need to accommodate supernumerary formative divisions, can account for the overall short root phenotype of BR signaling mutants. Tissue-specific re-addition of BRI1 activity partially rescued subsets of these defects through partly cell-autonomous, partly non-cell-autonomous effects. However, protophloem-specific BRI1 expression essentially rescued all major bri1 brl1 brl3 root meristem phenotypes. Our data suggest that BR perception in the protophloem is sufficient to systemically convey BR action in the root meristem context.

  10. 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.

  11. CdO nanoparticle toxicity on growth, morphology, and cell division in Escherichia coli.

    Science.gov (United States)

    Hossain, Sk Tofajjen; Mukherjee, Samir Kumar

    2012-12-04

    This Article deals with the toxicological study of synthesized CdO nanoparticles (NPs) on Escherichia coli . Characterization of the CdO NPs was done by DLS, XRD, TEM, and AFM studies, and the average size of NPs was revealed as 22 ± 3 nm. The NPs showed bactericidal activity against E. coli. When NPs were added at midlog phase of growth, complete growth inhibitory concentration was found as 40 μg/mL. Bacterial cells changed morphological features to filamentous form with increasing CdO NPs exposure time, and thereafter resulted in filamentation-associated clumping. From AFM study, severe damage of the cell surface was found in CdO NPs-treated cells. CdO NPs were found to interfere with the expression level of two conserved cell division components, ftsZ and ftsQ, in E. coli at both transcriptional and translational levels. Interference of CdO NPs in proper septum formation without affecting the nucleoid segregation was also observed in confocal micrographs. The elevated intracellular oxidative stress due to CdO NPs exposure seems to be one of the reasons for the changes in cell morphology and expression of division proteins in E. coli.

  12. Regenerative and immunogenic characteristics of cultured nucleus pulposus cells from human cervical intervertebral discs.

    Directory of Open Access Journals (Sweden)

    Stefan Stich

    Full Text Available Cell-based regenerative approaches have been suggested as primary or adjuvant procedures for the treatment of degenerated intervertebral disc (IVD diseases. Our aim was to evaluate the regenerative and immunogenic properties of mildly and severely degenerated cervical nucleus pulposus (NP cells with regard to cell isolation, proliferation and differentiation, as well as to cell surface markers and co-cultures with autologous or allogeneic peripheral blood mononuclear cells (PBMC including changes in their immunogenic properties after 3-dimensional (3D-culture. Tissue from the NP compartment of 10 patients with mild or severe grades of IVD degeneration was collected. Cells were isolated, expanded with and without basic fibroblast growth factor and cultured in 3D fibrin/poly (lactic-co-glycolic acid transplants for 21 days. Real-time reverse-transcription polymerase chain reaction (RT-PCR showed the expression of characteristic NP markers ACAN, COL1A1 and COL2A1 in 2D- and 3D-culture with degeneration- and culture-dependent differences. In a 5,6-carboxyfluorescein diacetate N-succinimidyl ester-based proliferation assay, NP cells in monolayer, regardless of their grade of degeneration, did not provoke a significant proliferation response in T cells, natural killer (NK cells or B cells, not only with donor PBMC, but also with allogeneic PBMC. In conjunction with low inflammatory cytokine expression, analyzed by Cytometric Bead Array and fluorescence-activated cell sorting (FACS, a low immunogenicity can be assumed, facilitating possible therapeutic approaches. In 3D-culture, however, we found elevated immune cell proliferation levels, and there was a general trend to higher responses for NP cells from severely degenerated IVD tissue. This emphasizes the importance of considering the specific immunological alterations when including biomaterials in a therapeutic concept. The overall expression of Fas receptor, found on cultured NP cells, could have

  13. Control of patterns of symmetric cell division in the epidermal and cortical tissues of the Arabidopsis root.

    Science.gov (United States)

    Zhang, Yanwen; Iakovidis, Michail; Costa, Silvia

    2016-03-15

    Controlled cell division is central to the growth and development of all multicellular organisms. Within the proliferating zone of the Arabidopsis root, regular symmetric divisions give rise to patterns of parallel files of cells, the genetic basis of which remains unclear. We found that genotypes impaired in the TONNEAU1a (TON1a) gene display misoriented symmetric divisions in the epidermis and have no division defects in the underlying cortical tissue. The TON1a gene encodes a microtubule-associated protein. We show that in the ton1a mutant, epidermal and cortical cells do not form narrow, ring-like preprophase bands (PPBs), which are plant-specific, cytoskeletal structures that predict the position of the division plane before mitosis. The results indicate that in the cortex but not in the epidermis, division plane positioning and patterning can proceed correctly in the absence of both a functional TON1a and PPB formation. Differences between tissues in how they respond to the signals that guide symmetric division orientation during patterning might provide the basis for organised organ growth in the absence of cell movements.

  14. The planar cell polarity (PCP) protein Diversin translocates to the nucleus to interact with the transcription factor AF9

    Energy Technology Data Exchange (ETDEWEB)

    Haribaskar, Ramachandran; Puetz, Michael; Schupp, Birte; Skouloudaki, Kassiani; Bietenbeck, Andreas; Walz, Gerd [Renal Division, University Hospital Freiburg, Hugstetter Strasse 55, D-79106 Freiburg (Germany); Schaefer, Tobias, E-mail: tobias.schaefer@uniklinik-freiburg.de [Renal Division, University Hospital Freiburg, Hugstetter Strasse 55, D-79106 Freiburg (Germany)

    2009-09-11

    The planar cell polarity (PCP) pathway, a {beta}-catenin-independent branch of the Wnt signaling pathway, orients cells and their appendages with respect to the body axes. Diversin, the mammalian homolog of the Drosophila PCP protein Diego, acts as a molecular switch that blocks {beta}-catenin-dependent and promotes {beta}-catenin-independent Wnt signaling. We report now that Diversin, containing several nuclear localization signals, translocates to the nucleus, where it interacts with the transcription factor AF9. Both Diversin and AF9 block canonical Wnt signaling; however, this occurs independently of each other, and does not require nuclear Diversin. In contrast, AF9 strongly augments the Diversin-driven activation of c-Jun N-terminal kinase (JNK)-dependent gene expression in the nucleus, and this augmentation largely depends on the presence of nuclear Diversin. Thus, our findings reveal that components of the PCP cascade translocate to the nucleus to participate in transcriptional regulation and PCP signaling.

  15. Identification of mayaro virus nucleocapsid protein in nucleus of Aedes albopictus cells.

    Science.gov (United States)

    Mitchell, C; de Andrade-Rozental, A F; Souto-Padrón, T; Carvalho, M G

    1997-01-01

    The modifications in the pattern of nuclear proteins of Aedes albopictus cells in response to Mayaro virus infection were analysed early and late after infection. The viral capsid (C) protein of 34 kDa (p34) could be detected in the nuclear compartment 4 h after infection, soon after its synthesis in the cytoplasm. In addition to p34, a group of high molecular weight proteins was also present in this compartment late after infection. The exposition of infected cells to supra optimal temperature of growth modifies significantly the pattern of nuclear proteins. However, the stress condition does not inhibit the transport of p34 to the nucleus. The transport of proteins into nuclei was also followed under "in vitro' conditions by incubating radiolabeled post-mitochondrial extract of infected cells with unlabeled nuclei. Under these conditions, as observed "in vivo', a specific transport of viral C protein and of a group of proteins of high molecular weight to the nuclei was also detected. These results indicate that Mayaro virus infection modifies the nuclear protein pattern in invertebrate cells.

  16. Dysfunction of nucleus accumbens-1 activates cellular senescence and inhibits tumor cell proliferation and oncogenesis.

    Science.gov (United States)

    Zhang, Yi; Cheng, Yan; Ren, Xingcong; Hori, Tsukasa; Huber-Keener, Kathryn J; Zhang, Li; Yap, Kai Lee; Liu, David; Shantz, Lisa; Qin, Zheng-Hong; Zhang, Suping; Wang, Jianrong; Wang, Hong-Gang; Shih, Ie-Ming; Yang, Jin-Ming

    2012-08-15

    Nucleus accumbens-1 (NAC1), a nuclear factor belonging to the BTB/POZ gene family, has emerging roles in cancer. We report here that NAC1 acts as a negative regulator of cellular senescence in transformed and nontransformed cells, and dysfunction of NAC1 induces senescence and inhibits its oncogenic potential. We show that NAC1 deficiency markedly activates senescence and inhibits proliferation in tumor cells treated with sublethal doses of γ-irradiation. In mouse embryonic fibroblasts from NAC1 knockout mice, following infection with a Ras virus, NAC1-/- cells undergo significantly more senescence and are either nontransformed or less transformed in vitro and less tumorigenic in vivo when compared with NAC1+/+ cells. Furthermore, we show that the NAC1-caused senescence blunting is mediated by ΔNp63, which exerts its effect on senescence through p21, and that NAC1 activates transcription of ΔNp63 under stressful conditions. Our results not only reveal a previously unrecognized function of NAC1, the molecular pathway involved and its impact on pathogenesis of tumor initiation and development, but also identify a novel senescence regulator that may be exploited as a potential target for cancer prevention and treatment.

  17. Late assembly of the Vibrio cholerae cell division machinery postpones septation to the last 10% of the cell cycle

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    Galli, Elisa; Paly, Evelyne; Barre, François-Xavier

    2017-01-01

    Bacterial cell division is a highly regulated process, which involves the formation of a complex apparatus, the divisome, by over a dozen proteins. In the few model bacteria in which the division process was detailed, divisome assembly occurs in two distinct steps: a few proteins, including the FtsZ tubulin-like protein, form a membrane associated contractile ring, the Z-ring, at ~30% of the cell cycle. The Z-ring serves as a scaffold for the recruitment of a second series of proteins, including integral membrane and periplasmic cell wall remodelling enzymes, at ~50% of the cell cycle. Actual septation occupies most of the remaining half of the cell cycle. In contrast, we present evidence suggesting that early pre-divisional Z-rings form between 40 and 50% of the cell cycle and mature into fully assembled divisome at about 80% of the cell cycle in Vibrio cholerae. Thus, actual septation is restricted to a very short amount of time. Our results further suggest that late assembly of the divisome probably helps maintain the asymmetric polar organisation of V. cholerae cells by limiting the accumulation of a cell pole marker, HubP, at the nascent cell poles. PMID:28300142

  18. A Prophage-Encoded Small RNA Controls Metabolism and Cell Division in Escherichia coli.

    Science.gov (United States)

    Balasubramanian, Divya; Ragunathan, Preethi T; Fei, Jingyi; Vanderpool, Carin K

    2016-01-01

    Hundreds of small RNAs (sRNAs) have been identified in diverse bacterial species, and while the functions of most remain unknown, some regulate key processes, particularly stress responses. The sRNA DicF was identified over 25 years ago as an inhibitor of cell division but since then has remained uncharacterized. DicF consists of 53 nucleotides and is encoded by a gene carried on a prophage (Qin) in the genomes of many Escherichia coli strains. We demonstrated that DicF inhibits cell division via direct base pairing with ftsZ mRNA to repress translation and prevent new synthesis of the bacterial tubulin homolog FtsZ. Systems analysis using computational and experimental methods identified additional mRNA targets of DicF: xylR and pykA mRNAs, encoding the xylose uptake and catabolism regulator and pyruvate kinase, respectively. Genetic analyses showed that DicF directly base pairs with and represses translation of these targets. Phenotypes of cells expressing DicF variants demonstrated that DicF-associated growth inhibition is not solely due to repression of ftsZ, indicating that the physiological consequences of DicF-mediated regulation extend beyond effects on cell division caused by reduced FtsZ synthesis. IMPORTANCE sRNAs are ubiquitous and versatile regulators of bacterial gene expression. A number of well-characterized examples in E. coli are highly conserved and present in the E. coli core genome. In contrast, the sRNA DicF (identified over 20 years ago but remaining poorly characterized) is encoded by a gene carried on a defective prophage element in many E. coli genomes. Here, we characterize DicF in order to better understand how horizontally acquired sRNA regulators impact bacterial gene expression and physiology. Our data confirm the long-hypothesized DicF-mediated regulation of ftsZ, encoding the bacterial tubulin homolog required for cell division. We further uncover DicF-mediated posttranscriptional control of metabolic gene expression. Ectopic

  19. Characterization of novel photocrosslinked carboxymethylcellulose hydrogels for encapsulation of nucleus pulposus cells.

    Science.gov (United States)

    Reza, Anna T; Nicoll, Steven B

    2010-01-01

    Back pain is a significant clinical concern often associated with degeneration of the intervertebral disc (IVD). Tissue engineering strategies may provide a viable IVD replacement therapy; however, an ideal biomaterial scaffold has yet to be identified. One candidate material is carboxymethylcellulose (CMC), a water-soluble derivative of cellulose. In this study, 90 and 250 kDa CMC polymers were modified with functional methacrylate groups and photocrosslinked to produce hydrogels at different macromer concentrations. At 7 days, bovine nucleus pulposus (NP) cells encapsulated in these hydrogels were viable, with values for the elastic modulus ranging from 1.07 + or - 0.06 to 4.29 + or - 1.25 kPa. Three specific formulations were chosen for further study based on cell viability and mechanical integrity assessments: 4% 90 kDa, 2% 250 kDa and 3% 250 kDa CMC. The equilibrium weight swelling ratio of these formulations remained steady throughout the 2 week study (46.45 + or - 3.14, 48.55 + or - 2.91 and 42.41 + or - 3.06, respectively). The equilibrium Young's modulus of all cell-laden and cell-free control samples decreased over time, with the exception of cell-laden 3% 250 kDa CMC constructs, indicating an interplay between limited hydrolysis of interchain crosslinks and the elaboration of a functional matrix. Histological analyses of 3% 250 kDa CMC hydrogels confirmed the presence of rounded cells in lacunae and the pericellular deposition of chondroitin sulfate proteoglycan, a phenotypic NP marker. Taken together, these studies support the use of photocrosslinked CMC hydrogels as tunable biomaterials for NP cell encapsulation.

  20. Herbicide effects on freshwater benthic diatoms: Induction of nucleus alterations and silica cell wall abnormalities

    Energy Technology Data Exchange (ETDEWEB)

    Debenest, T. [Ecolab UMR 5245 (INP ENSAT, CNRS, UPS), Equipe ECOGEN, Avenue de l' Agrobiopole - BP 32607 Auzeville Tolosane, 31326 Castanet Tolosan Cedex (France); Cemagref, 50 avenue de Verdun, 33612 Cestas Cedex (France); Silvestre, J. [Ecolab UMR 5245 (INP ENSAT, CNRS, UPS), Equipe ECOGEN, Avenue de l' Agrobiopole - BP 32607 Auzeville Tolosane, 31326 Castanet Tolosan Cedex (France); Coste, M.; Delmas, F. [Cemagref, 50 avenue de Verdun, 33612 Cestas Cedex (France); Pinelli, E. [Ecolab UMR 5245 (INP ENSAT, CNRS, UPS), Equipe ECOGEN, Avenue de l' Agrobiopole - BP 32607 Auzeville Tolosane, 31326 Castanet Tolosan Cedex (France)], E-mail: pinelli@ensat.fr

    2008-06-02

    Benthic diatoms are well known bio-indicators of river pollution by nutrients (nitrogen and phosphorus). Biological indexes, based on diatom sensitivity for non-toxic pollution, have been developed to assess the water quality. Nevertheless, they are not reliable tools to detect pollution by pesticides. Many authors have suggested that toxic agents, like pesticides, induce abnormalities of the diatom cell wall (frustule). High abnormal frustule abundances have been reported in natural diatom communities sampled in streams contaminated by pesticides. However, no direct link was found between the abundances of abnormal frustules in these communities and the pesticide concentrations in stream water. In the present study, a freshwater benthic diatom community, isolated from natural biofilm and cultured under controlled conditions, was treated with a known genotoxic herbicide, maleic hydrazide (MH). Cells were exposed to three concentrations of MH (5 x 10{sup -6}, 10{sup -6}, 10{sup -7} M) for 6 h followed by a 24 h-recovery time. After MH treatments, nucleus alterations were observed: abnormal nucleus location, micronucleus, multinuclear cell or disruption of the nuclear membrane. A dose-dependent increase of nuclear alterations was observed. The difference between the control (9.65 nuclear alterations per 1000 cells observed (9.65 per mille), S.D. = 4.23) and the highest concentrations (29.40 per mille, S.D. = 8.49 for 10{sup -6} M and 35.96 per mille , S.D. = 3.71 for 5 x 10{sup -6} M) was statistically significant (Tukey test, P < 0.05). Diatoms also exhibited frustules with deformed morphology and abnormal ornamentation. Significantly increased abundances of abnormal frustules were observed for the highest concentrations (10{sup -6} and 5 x 10{sup -6} M; Tukey test, P < 0.05). These two parameters tended to increase together (Pearson correlation = 0.702, P < 0.05). The results suggest that the induction of abnormal frustules could be associated with the genotoxic

  1. Judging diatoms by their cover: variability in local elasticity of Lithodesmium undulatum undergoing cell division.

    Directory of Open Access Journals (Sweden)

    Lee Karp-Boss

    Full Text Available Unique features of diatoms are their intricate cell covers (frustules made out of hydrated, amorphous silica. The frustule defines and maintains cell shape and protects cells against grazers and pathogens, yet it must allow for cell expansion during growth and division. Other siliceous structures have also evolved in some chain-forming species as means for holding neighboring cells together. Characterization and quantification of mechanical properties of these structures are crucial for the understanding of the relationship between form and function in diatoms, but thus far only a handful of studies have addressed this issue. We conducted micro-indentation experiments, using atomic force microscopy (AFM, to examine local variations in elastic (Young's moduli of cells and linking structures in the marine, chain-forming diatom Lithodesmium undulatum. Using a fluorescent tracer that is incorporated into new cell wall components we tested the hypothesis that new siliceous structures differ in elastic modulus from their older counterparts. Results show that the local elastic modulus is a highly dynamic property. Elastic modulus of stained regions was significantly lower than that of unstained regions, suggesting that newly formed cell wall components are generally softer than the ones inherited from the parent cells. This study provides the first evidence of differentiation in local elastic properties in the course of the cell cycle. Hardening of newly formed regions may involve incorporation of additional, possibly organic, material but further studies are needed to elucidate the processes that regulate mechanical properties of the frustule during the cell cycle.

  2. Accelerated cell divisions drive the outgrowth of the regenerating spinal cord in axolotls

    Science.gov (United States)

    Rost, Fabian; Albors, Aida Rodrigo; Mazurov, Vladimir; Brusch, Lutz; Deutsch, Andreas

    2016-01-01

    Axolotls are unique in their ability to regenerate the spinal cord. However, the mechanisms that underlie this phenomenon remain poorly understood. Previously, we showed that regenerating stem cells in the axolotl spinal cord revert to a molecular state resembling embryonic neuroepithelial cells and functionally acquire rapid proliferative divisions (Rodrigo Albors et al., 2015). Here, we refine the analysis of cell proliferation in space and time and identify a high-proliferation zone in the regenerating spinal cord that shifts posteriorly over time. By tracking sparsely-labeled cells, we also quantify cell influx into the regenerate. Taking a mathematical modeling approach, we integrate these quantitative datasets of cell proliferation, neural stem cell activation and cell influx, to predict regenerative tissue outgrowth. Our model shows that while cell influx and neural stem cell activation play a minor role, the acceleration of the cell cycle is the major driver of regenerative spinal cord outgrowth in axolotls. DOI: http://dx.doi.org/10.7554/eLife.20357.001 PMID:27885987

  3. 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.

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

    Science.gov (United States)

    Damodaran, Shima P; Eberhard, Stephan; Boitard, Laurent; Rodriguez, Jairo Garnica; Wang, Yuxing; Bremond, Nicolas; Baudry, Jean; Bibette, Jérôme; Wollman, Francis-André

    2015-01-01

    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.

  5. Egf Signaling Directs Neoblast Repopulation by Regulating Asymmetric Cell Division in Planarians.

    Science.gov (United States)

    Lei, Kai; Thi-Kim Vu, Hanh; Mohan, Ryan D; McKinney, Sean A; Seidel, Chris W; Alexander, Richard; Gotting, Kirsten; Workman, Jerry L; Sánchez Alvarado, Alejandro

    2016-08-22

    A large population of proliferative stem cells (neoblasts) is required for physiological tissue homeostasis and post-injury regeneration in planarians. Recent studies indicate that survival of a few neoblasts after sublethal irradiation results in the clonal expansion of the surviving stem cells and the eventual restoration of tissue homeostasis and regenerative capacity. However, the precise mechanisms regulating the population dynamics of neoblasts remain largely unknown. Here, we uncovered a central role for epidermal growth factor (EGF) signaling during in vivo neoblast expansion mediated by Smed-egfr-3 (egfr-3) and its putative ligand Smed-neuregulin-7 (nrg-7). Furthermore, the EGF receptor-3 protein localizes asymmetrically on the cytoplasmic membrane of neoblasts, and the ratio of asymmetric to symmetric cell divisions decreases significantly in egfr-3(RNAi) worms. Our results not only provide the first molecular evidence of asymmetric stem cell divisions in planarians, but also demonstrate that EGF signaling likely functions as an essential regulator of neoblast clonal expansion.

  6. 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.

  7. Regulation of cell divisions and differentiation by MALE STERILITY32 is required for anther development in maize.

    Science.gov (United States)

    Moon, Jihyun; Skibbe, David; Timofejeva, Ljudmilla; Wang, Chung-Ju Rachel; Kelliher, Timothy; Kremling, Karl; Walbot, Virginia; Cande, William Zacheus

    2013-11-01

    Male fertility in flowering plants relies on proper division and differentiation of cells in the anther, a process that gives rise to four somatic layers surrounding central germinal cells. The maize gene male sterility32 (ms32) encodes a basic helix-loop-helix (bHLH) transcription factor, which functions as an important regulator of both division and differentiation during anther development. After the four somatic cell layers are generated properly through successive periclinal divisions, in the ms32 mutant, tapetal precursor cells fail to differentiate, and, instead, undergo additional periclinal divisions to form extra layers of cells. These cells become vacuolated and expand, and lead to failure in pollen mother cell development. ms32 expression is specific to the pre-meiotic anthers and is distributed initially broadly in the four lobes, but as the anther develops, its expression becomes restricted to the innermost somatic layer, the tapetum. The ms32-ref mac1-1 double mutant is unable to form tapetal precursors and also exhibits excessive somatic proliferation leading to numerous, disorganized cell layers, suggesting a synergistic interaction between ms32 and mac1. Altogether, our results show that MS32 is a major regulator in maize anther development that promotes tapetum differentiation and inhibits periclinal division once a tapetal cell is specified.

  8. Crystal structure of the Z-ring associated cell division protein ZapC from Escherichia coli.

    Science.gov (United States)

    Ortiz, Cristina; Kureisaite-Ciziene, Danguole; Schmitz, Florian; McLaughlin, Stephen H; Vicente, Miguel; Löwe, Jan

    2015-12-21

    Bacterial cell division involves a contractile ring that organises downstream proteins at the division site and which contains the tubulin homologue FtsZ. ZapC has been discovered as a non-essential regulator of FtsZ. It localises to the septal ring and deletion of zapC leads to a mild phenotype, while overexpression inhibits cell division. Interference with cell division is facilitated by an interaction with FtsZ. Here, we present the 2.9 Å crystal structure of ZapC from Escherichia coli. ZapC forms a dimer and comprises two domains that belong to the Royal superfamily of which many members bind methylated arginines or lysines. ZapC contains an N-terminal chromo-like domain and a Tudor-like C-terminal domain. We show by ITC that ZapC binds the C-terminal tail of FtsZ.

  9. HHV-8 encoded LANA-1 alters the higher organization of the cell nucleus

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    Klein George

    2007-04-01

    Full Text Available Abstract The latency-associated nuclear antigen (LANA-1 of Human Herpes Virus 8 (HHV-8, alternatively called Kaposi Sarcoma Herpes Virus (KSHV is constitutively expressed in all HHV-8 infected cells. LANA-1 accumulates in well-defined foci that co-localize with the viral episomes. We have previously shown that these foci are tightly associated with the borders of heterochromatin 1. We have also shown that exogenously expressed LANA-1 causes an extensive re-organization of Hoechst 33248 DNA staining patterns of the nuclei in non-HHV-8 infected cells 2. Here we show that this effect includes the release of the bulk of DNA from heterochromatic areas, in both human and mouse cells, without affecting the overall levels of heterochromatin associated histone H3 lysine 9 tri-methylation (3MK9H3. The release of DNA from the heterochromatic chromocenters in LANA-1 transfected mouse cells co-incides with the dispersion of the chromocenter associated methylcytosin binding protein 2 (MECP2. The localization of 3MK9H3 to the remnants of the chromocenters remains unaltered. Moreover, exogeneously expressed LANA-1 leads to the relocation of the chromocenters to the nuclear periphery, indicating extensive changes in the positioning of the chromosomal domains in the LANA-1 harboring interphase nucleus. Using a series of deletion mutants we have shown that the chromatin rearranging effects of LANA-1 require the presence of a short (57 amino acid region that is located immediately upstream of the internal acidic repeats. This sequence lies within the previously mapped binding site to histone methyltransferase SUV39H1. We suggest that the highly concentrated LANA-1, anchored to the host genome in the nuclear foci of latently infected cells and replicated through each cell generation, may function as "epigenetic modifier". The induction of histone modification in adjacent host genes may lead to altered gene expression, thereby contributing to the viral oncogenesis.

  10. Periodic mechanical stress activates EGFR-dependent Rac1 mitogenic signals in rat nucleus pulpous cells via ERK1/2.

    Science.gov (United States)

    Gao, Gongming; Shen, Nan; Jiang, Xuefeng; Sun, Huiqing; Xu, Nanwei; Zhou, Dong; Nong, Luming; Ren, Kewei

    2016-01-15

    The mitogenic effects of periodic mechanical stress on nucleus pulpous cells have been studied extensively but the mechanisms whereby nucleus pulpous cells sense and respond to mechanical stimulation remain a matter of debate. We explored this question by performing cell culture experiments in our self-developed periodic stress field and perfusion culture system. Under periodic mechanical stress, rat nucleus pulpous cell proliferation was significantly increased (p mechanical stress-induced nucleus pulpous cell proliferation (p mechanical stress (p mechanical stress (p mechanical stress promotes nucleus pulpous cell proliferation in part through the EGFR-Rac1-ERK1/2 signaling pathway, which links these three important signaling molecules into a mitogenic cascade.

  11. Positioning of polarity formation by extracellular signaling during asymmetric cell division.

    Science.gov (United States)

    Seirin Lee, Sungrim

    2016-07-07

    Anterior-posterior (AP) polarity formation of cell membrane proteins plays a crucial role in determining cell asymmetry, which ultimately generates cell diversity. In Caenorhabditis elegans, a single fertilized egg cell (P0), its daughter cell (P1), and the germline precursors (P2 and P3 cells) form two exclusive domains of different PAR proteins on the membrane along the anterior-posterior axis. However, the phenomenon of polarity reversal has been observed in which the axis of asymmetric cell division of the P2 and P3 cells is formed in an opposite manner to that of the P0 and P1 cells. The extracellular signal MES-1/SRC-1 has been shown to induce polarity reversal, but the detailed mechanism remains elusive. Here, using a mathematical model, I explore the mechanism by which MES-1/SRC-1 signaling can induce polarity reversal and ultimately affect the process of polarity formation. I show that a positive correlation between SRC-1 and the on-rate of PAR-2 is the essential mechanism underlying polarity reversal, providing a mathematical basis for the orientation of cell polarity patterns.

  12. Computational prediction of Mycoplasma hominis proteins targeting in nucleus of host cell and their implication in prostate cancer etiology.

    Science.gov (United States)

    Khan, Shahanavaj; Zakariah, Mohammed; Palaniappan, Sellappan

    2016-08-01

    Cancer has long been assumed to be a genetic disease. However, recent evidence supports the enigmatic connection of bacterial infection with the growth and development of various types of cancers. The cause and mechanism of the growth and development of prostate cancer due to Mycoplasma hominis remain unclear. Prostate cancer cells are infected and colonized by enteroinvasive M. hominis, which controls several factors that can affect prostate cancer growth in susceptible persons. We investigated M. hominis proteins targeting the nucleus of host cells and their implications in prostate cancer etiology. Many vital processes are controlled in the nucleus, where the proteins targeting M. hominis may have various potential implications. A total of 29/563 M. hominis proteins were predicted to target the nucleus of host cells. These include numerous proteins with the capability to alter normal growth activities. In conclusion, our results emphasize that various proteins of M. hominis targeted the nucleus of host cells and were involved in prostate cancer etiology through different mechanisms and strategies.

  13. Oriented cell divisions and cellular morphogenesis in the zebrafish gastrula and neurula: a time-lapse analysis.

    Science.gov (United States)

    Concha, M L; Adams, R J

    1998-03-01

    We have taken advantage of the optical transparency of zebrafish embryos to investigate the patterns of cell division, movement and shape during early stages of development of the central nervous system. The surface-most epiblast cells of gastrula and neurula stage embryos were imaged and analysed using a computer-based, time-lapse acquisition system attached to a differential interference contrast (DIC) microscope. We find that the onset of gastrulation is accompanied by major changes in cell behaviour. Cells collect into a cohesive sheet, apparently losing independent motility and integrating their behaviour to move coherently over the yolk in a direction that is the result of two influences: towards the vegetal pole in the movements of epiboly and towards the dorsal midline in convergent movements that strengthen throughout gastrulation. Coincidentally, the plane of cell division becomes aligned to the surface plane of the embryo and oriented in the anterior-posterior (AP) direction. These behaviours begin at the blastoderm margin and propagate in a gradient towards the animal pole. Later in gastrulation, cells undergo increasingly mediolateral-directed elongation and autonomous convergence movements towards the dorsal midline leading to an enormous extension of the neural axis. Around the equator and along the dorsal midline of the gastrula, persistent AP orientation of divisions suggests that a common mechanism may be involved but that neither oriented cell movements nor shape can account for this alignment. When the neural plate begins to differentiate, there is a gradual transition in the direction of cell division from AP to the mediolateral circumference (ML). ML divisions occur in both the ventral epidermis and dorsal neural plate. In the neural plate, ML becomes the predominant orientation of division during neural keel and nerve rod stages and, from late neural keel stage, divisions are concentrated at the dorsal midline and generate bilateral progeny

  14. Mechanics of kinetochore microtubules and their interactions with chromosomes during cell division

    Science.gov (United States)

    Nazockdast, Ehssan; Fürthauer, Sebastian; Redemann, Stephanie; Baumgart, Johannes; Lindow, Norbert; Kratz, Andrea; Prohaska, Steffen; Müller-Reichert, Thomas; Shelley, Michael

    2016-11-01

    The accurate segregation of chromosomes, and subsequent cell division, in Eukaryotic cells is achieved by the interactions of an assembly of microtubules (MTs) and motor-proteins, known as the mitotic spindle. We use a combination of our computational platform for simulating cytoskeletal assemblies and our structural data from high-resolution electron tomography of the mitotic spindle, to study the kinetics and mechanics of MTs in the spindle, and their interactions with chromosomes during chromosome segregation in the first cell division in C.elegans embryo. We focus on kinetochore MTs, or KMTs, which have one end attached to a chromosome. KMTs are thought to be a key mechanical component in chromosome segregation. Using exploratory simulations of MT growth, bending, hydrodynamic interactions, and attachment to chromosomes, we propose a mechanical model for KMT-chromosome interactions that reproduces observed KMT length and shape distributions from electron tomography. We find that including detailed hydrodynamic interactions between KMTs is essential for agreement with the experimental observations.

  15. The nucleus of endothelial cell as a sensor of blood flow direction

    Directory of Open Access Journals (Sweden)

    Eugene Tkachenko

    2013-08-01

    Hemodynamic shear stresses cause endothelial cells (ECs to polarize in the plane of the flow. Paradoxically, under strong shear flows, ECs disassemble their primary cilia, common sensors of shear, and thus must use an alternative mechanism of sensing the strength and direction of flow. In our experiments in microfluidic perfusion chambers, confluent ECs developed planar cell polarity at a rate proportional to the shear stress. The location of Golgi apparatus and microtubule organizing center was biased to the upstream side of the nucleus, i.e. the ECs polarized against the flow. These in vitro results agreed with observations in murine blood vessels, where EC polarization against the flow was stronger in high flow arteries than in veins. Once established, flow-induced polarization persisted over long time intervals without external shear. Transient destabilization of acto-myosin cytoskeleton by inhibition of myosin II or depolymerization of actin promoted polarization of EC against the flow, indicating that an intact acto-myosin cytoskeleton resists flow-induced polarization. These results suggested that polarization was induced by mechanical displacement of EC nuclei downstream under the hydrodynamic drag. This hypothesis was confirmed by the observation that acute application of a large hydrodynamic force to ECs resulted in an immediate downstream displacement of nuclei and was sufficient to induce persistent polarization. Taken together, our data indicate that ECs can sense the direction and strength of blood flow through the hydrodynamic drag applied to their nuclei.

  16. Completion of cell division is associated with maximum telomerase activity in naturally synchronized cultures of the green alga Desmodesmus quadricauda.

    Science.gov (United States)

    Ševčíková, Tereza; Bišová, Kateřina; Fojtová, Miloslava; Lukešová, Alena; Hrčková, Kristýna; Sýkorová, Eva

    2013-03-18

    Telomerase maintains the ends of eukaryotic chromosomes, and its activity is an important parameter correlating with the proliferative capacity of cells. We have investigated cell cycle-specific changes in telomerase activity using cultures of Desmodesmus quadricauda, a model alga naturally synchronized by light/dark entrainment. A quantitative telomerase assay revealed high activity in algal cultures, with slight changes during the light period. Significantly increased telomerase activity was observed at the end of the dark phase, when cell division was complete. In contrast to other models, a natural separation between nuclear and cellular division typical for the cell cycle in D. quadricauda made this observation possible.

  17. DGCR8 Localizes to the Nucleus as well as Cytoplasmic Structures in Mammalian Spermatogenic Cells and Epididymal Sperm

    Directory of Open Access Journals (Sweden)

    Akane Nakano

    2013-01-01

    Full Text Available The localization of DGCR8 in spermatogenic cells and sperm from rat and mouse was studied by immunofluorescence and immunoelectron microscopy. Spermatogenic cells from these species yielded similar DGCR8 localization pattern. Immunofluorescence microscopy results showed that DGCR8 localized to both the cytoplasm and nucleus. In the cytoplasm, diffuse cytosolic and discrete granular staining was observed. Dual staining showed that DGCR8 colocalized to the granules with MAEL (a nuage marker. In the nucleus of spermatocytes, both the nucleoli and nucleoplasm were stained, whereas in the nucleus of early spermatids small spots were stained. In late spermatids, DGCR8 localized to the tip of their head and to small granules (neck granules of the neck cytoplasm. The neck granules were also observed in the neck of epididymal sperm. Immunoelectron microscopy results showed that DGCR8 localized to nuage structures. Moreover, DGCR8 localized to nonnuage structures in late spermatids. DGCR8 also localized to the nucleolus and euchromatin in spermatocytes and round spermatids and to small granules in the nucleus of late spermatids. The results suggest that in spermatogenic cells DGCR8 localizes not only to the nuclei but also to the cytoplasmic structures such as nuage and nonnuage structures. Furthermore, DGCR8 seems to be imported into the egg with neck granules in sperm during fertilization.

  18. Inhibition of phenylpropanoid biosynthesis increases cell wall digestibility, protoplast isolation, and facilitates sustained cell division in American elm (Ulmus americana

    Directory of Open Access Journals (Sweden)

    Jones A Maxwell P

    2012-05-01

    Full Text Available Abstract Background Protoplast technologies offer unique opportunities for fundamental research and to develop novel germplasm through somatic hybridization, organelle transfer, protoclonal variation, and direct insertion of DNA. Applying protoplast technologies to develop Dutch elm disease resistant American elms (Ulmus americana L. was proposed over 30 years ago, but has not been achieved. A primary factor restricting protoplast technology to American elm is the resistance of the cell walls to enzymatic degradation and a long lag phase prior to cell wall re-synthesis and cell division. Results This study suggests that resistance to enzymatic degradation in American elm was due to water soluble phenylpropanoids. Incubating tobacco (Nicotiana tabacum L. leaf tissue, an easily digestible species, in aqueous elm extract inhibits cell wall digestion in a dose dependent manner. This can be mimicked by p-coumaric or ferulic acid, phenylpropanoids known to re-enforce cell walls. Culturing American elm tissue in the presence of 2-aminoindane-2-phosphonic acid (AIP; 10-150 μM, an inhibitor of phenylalanine ammonia lyase (PAL, reduced flavonoid content, decreased tissue browning, and increased isolation rates significantly from 11.8% (±3.27 in controls to 65.3% (±4.60. Protoplasts isolated from callus grown in 100 μM AIP developed cell walls by day 2, had a division rate of 28.5% (±3.59 by day 6, and proliferated into callus by day 14. Heterokaryons were successfully produced using electrofusion and fused protoplasts remained viable when embedded in agarose. Conclusions This study describes a novel approach of modifying phenylpropanoid biosynthesis to facilitate efficient protoplast isolation which has historically been problematic for American elm. This isolation system has facilitated recovery of viable protoplasts capable of rapid cell wall re-synthesis and sustained cell division to form callus. Further, isolated protoplasts survived

  19. Activity of cells in the lateral vestibular nucleus as a function of head position

    Science.gov (United States)

    Fujita, Y.; Rosenberg, Jay; Segundo, J. P.

    1968-01-01

    1. The spike activity of cells in the lateral vestibular nucleus was recorded in cats anaesthetized with pentobarbital sodium. Natural labyrinthine stimulation was applied by fixing the animal at different positions reached through roations about a longitudinal or transverse axis. 2. The majority of cells responded to rotations only about the longitudinal axis. Two types of response were found. The first was characterized by a transient change in activity which occurred only during the movement. The second type had an initial transient component and a subsequent steady component that persisted as long as the head remained fixed. 3. The interspike interval means, standard deviations, histograms and autocorrelograms of the steady response components of cells sensitive to lateral tilt were calculated. In every cell the relation between the head position with respect to gravity and the mean interspike interval of the steady discharge showed two main features. (a) `Directional sensitivity': the mean interval increased following rotation in one sense, and decreased following rotation in the other. In twenty-two out of thirty-three cells, the mean increased when the recording side was raised. The remaining cells showed the opposite relation. (b) `Multivaluedness': each particular position is associated with several different values of mean interval and these values had a relatively wide scatter. The curve that resulted from joining points in the order in which they occurred during the experiment was either closed, open, or combined closed and open portions. 4. The standard deviations, histograms and autocorrelograms also showed directional sensitivity and multivaluedness with respect to position. Several types of interspike interval histograms and autocorrelograms characterized lateral vestibular activity. The forms of the histogram and the autocorrelogram of the discharge from each cell usually remained unchanged during stimulation. 5. The extensive spread of the

  20. A model for the Escherichia coli FtsB/FtsL/FtsQ cell division complex

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    Lagos Rosalba

    2011-06-01

    Full Text Available Abstract Background Bacterial division is produced by the formation of a macromolecular complex in the middle of the cell, called the divisome, formed by more than 10 proteins. This process can be divided into two steps, in which the first is the polymerization of FtsZ to form the Z ring in the cytoplasm, and then the sequential addition of FtsA/ZipA to anchor the ring at the cytoplasmic membrane, a stage completed by FtsEX and FtsK. In the second step, the formation of the peptidoglycan synthesis machinery in the periplasm takes place, followed by cell division. The proteins involved in connecting both steps in cell division are FtsQ, FtsB and FtsL, and their interaction is a crucial and conserved event in the division of different bacteria. These components are small bitopic membrane proteins, and their specific function seems to be mainly structural. The purpose of this study was to obtain a structural model of the periplasmic part of the FtsB/FtsL/FtsQ complex, using bioinformatics tools and experimental data reported in the literature. Results Two oligomeric models for the periplasmic region of the FtsB/FtsL/FtsQ E. coli complex were obtained from bioinformatics analysis. The FtsB/FtsL subcomplex was modelled as a coiled-coil based on sequence information and several stoichiometric possibilities. The crystallographic structure of FtsQ was added to this complex, through protein-protein docking. Two final structurally-stable models, one trimeric and one hexameric, were obtained. The nature of the protein-protein contacts was energetically favourable in both models and the overall structures were in agreement with the experimental evidence reported. Conclusions The two models obtained for the FtsB/FtsL/FtsQ complex were stable and thus compatible with the in vivo periplasmic complex structure. Although the hexameric model 2:2:2 has features that indicate that this is the most plausible structure, the ternary complex 1:1:1 cannot be discarded

  1. 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.

  2. Molecular Insights into Division of Single Human Cancer Cells in On-Chip Transparent Microtubes

    Science.gov (United States)

    2016-01-01

    In vivo, mammalian cells proliferate within 3D environments consisting of numerous microcavities and channels, which contain a variety of chemical and physical cues. External environments often differ between normal and pathological states, such as the unique spatial constraints that metastasizing cancer cells experience as they circulate the vasculature through arterioles and narrow capillaries, where they can divide and acquire elongated cylindrical shapes. While metastatic tumors cause most cancer deaths, factors impacting early cancer cell proliferation inside the vasculature and those that can promote the formation of secondary tumors remain largely unknown. Prior studies investigating confined mitosis have mainly used 2D cell culture systems. Here, we mimic aspects of metastasizing tumor cells dividing inside blood capillaries by investigating single-cell divisions of living human cancer cells, trapped inside 3D rolled-up, transparent nanomembranes. We assess the molecular effects of tubular confinement on key mitotic features, using optical high- and super-resolution microscopy. Our experiments show that tubular confinement affects the morphology and dynamics of the mitotic spindle, chromosome arrangements, and the organization of the cell cortex. Moreover, we reveal that membrane blebbing and/or associated processes act as a potential genome-safety mechanism, limiting the extent of genomic instability caused by mitosis in confined circumstances, especially in tubular 3D microenvironments. Collectively, our study demonstrates the potential of rolled-up nanomembranes for gaining molecular insights into key cellular events occurring in tubular 3D microenvironments in vivo. PMID:27267364

  3. Heterogeneity, Cell Biology and Tissue Mechanics of Pseudostratified Epithelia: Coordination of Cell Divisions and Growth in Tightly Packed Tissues.

    Science.gov (United States)

    Strzyz, P J; Matejcic, M; Norden, C

    2016-01-01

    Pseudostratified epithelia (PSE) are tightly packed proliferative tissues that are important precursors of the development of diverse organs in a plethora of species, invertebrate and vertebrate. PSE consist of elongated epithelial cells that are attached to the apical and basal side of the tissue. The nuclei of these cells undergo interkinetic nuclear migration (IKNM) which leads to all mitotic events taking place at the apical surface of the epithelium. In this review, we discuss the intricacies of proliferation in PSE, considering cell biological, as well as the physical aspects. First, we summarize the principles governing the invariability of apical nuclear migration and apical cell division as well as the importance of apical mitoses for tissue proliferation. Then, we focus on the mechanical and structural features of these tissues. Here, we discuss how the overall architecture of pseudostratified tissues changes with increased cell packing. Lastly, we consider possible mechanical cues resulting from these changes and their potential influence on cell proliferation.

  4. 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.

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

    Science.gov (United States)

    Li, Zhiru; Garner, Amanda L; Gloeckner, Christian; Janda, Kim D; Carlow, Clotilde K

    2011-11-01

    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).

  6. The Type IVa Pilus Machinery Is Recruited to Sites of Future Cell Division.

    Science.gov (United States)

    Carter, Tyson; Buensuceso, Ryan N C; Tammam, Stephanie; Lamers, Ryan P; Harvey, Hanjeong; Howell, P Lynne; Burrows, Lori L

    2017-01-31

    Type IVa pili (T4aP) are ubiquitous microbial appendages used for adherence, twitching motility, DNA uptake, and electron transfer. Many of these functions depend on dynamic assembly and disassembly of the pilus by a megadalton-sized, cell envelope-spanning protein complex located at the poles of rod-shaped bacteria. How the T4aP assembly complex becomes integrated into the cell envelope in the absence of dedicated peptidoglycan (PG) hydrolases is unknown. After ruling out the potential involvement of housekeeping PG hydrolases in the installation of the T4aP machinery in Pseudomonas aeruginosa, we discovered that key components of inner (PilMNOP) and outer (PilQ) membrane subcomplexes are recruited to future sites of cell division. Midcell recruitment of a fluorescently tagged alignment subcomplex component, mCherry-PilO, depended on PilQ secretin monomers-specifically, their N-terminal PG-binding AMIN domains. PilP, which connects PilO to PilQ, was required for recruitment, while PilM, which is structurally similar to divisome component FtsA, was not. Recruitment preceded secretin oligomerization in the outer membrane, as loss of the PilQ pilotin PilF had no effect on localization. These results were confirmed in cells chemically blocked for cell division prior to outer membrane invagination. The hub protein FimV and a component of the polar organelle coordinator complex-PocA-were independently required for midcell recruitment of PilO and PilQ. Together, these data suggest an integrated, energy-efficient strategy for the targeting and preinstallation-rather than retrofitting-of the T4aP system into nascent poles, without the need for dedicated PG-remodeling enzymes.

  7. Entropyomics as the Blueprint of the Logic of Normal Cell Division and Malignancy

    Directory of Open Access Journals (Sweden)

    Kambiz Afrasiabi

    2011-01-01

    Full Text Available Problem statement: In this article I propose a blueprint based on one of the most fundamental laws governing the known universe, namely the second law of thermodynamics and I present support for its central role in initiation of mitosis and relationship of the other sub cellular compartments and their organization. Approach: Life is considered to be the most sophisticated antientropy machinery ever born on the face of the universe as far as its power to minimize the speed of rise in entropy is concerned, however we all get old, sick and die because it is not possible to stop the rise in entropy based on the nature of the known universe. Results: Lack of understanding of the scientific foundation of logic of the normal cell division has surrounded us by darkness and has made analysis of an ever increasing and explosive amount of information originating from whole genome sequencing, genomics, exonomics, proteomics and metabolomics more problematic. Clearly this understanding is the prerequisite for understanding of pathological states of cell division including malignancy. Conclusion/Recommendations: The main approach to this problem is calculation of the free energy of the master regulator proteins of the intracellular communication network of the cancer stem cell and its normal counterpart which in turn could get identified by the available mathematical models that could identify master regulator proteins of the intracellular communication network and deciphering the difference by spectrophotometry at a given wavelength of light and identification of higher absorbance in the malignant counterpart and designing epigenetic or homologous recombination mediated methodology using nanotechology as a delivery mechanism targeting transcription of mRNAs which would lead to protein products with a normal free energy for that cell lineage / higher free energy compared with its malignant counterpart and by doing so we could convert the

  8. The Type IVa Pilus Machinery Is Recruited to Sites of Future Cell Division

    Science.gov (United States)

    Carter, Tyson; Buensuceso, Ryan N. C.; Tammam, Stephanie; Lamers, Ryan P.; Harvey, Hanjeong

    2017-01-01

    ABSTRACT Type IVa pili (T4aP) are ubiquitous microbial appendages used for adherence, twitching motility, DNA uptake, and electron transfer. Many of these functions depend on dynamic assembly and disassembly of the pilus by a megadalton-sized, cell envelope-spanning protein complex located at the poles of rod-shaped bacteria. How the T4aP assembly complex becomes integrated into the cell envelope in the absence of dedicated peptidoglycan (PG) hydrolases is unknown. After ruling out the potential involvement of housekeeping PG hydrolases in the installation of the T4aP machinery in Pseudomonas aeruginosa, we discovered that key components of inner (PilMNOP) and outer (PilQ) membrane subcomplexes are recruited to future sites of cell division. Midcell recruitment of a fluorescently tagged alignment subcomplex component, mCherry-PilO, depended on PilQ secretin monomers—specifically, their N-terminal PG-binding AMIN domains. PilP, which connects PilO to PilQ, was required for recruitment, while PilM, which is structurally similar to divisome component FtsA, was not. Recruitment preceded secretin oligomerization in the outer membrane, as loss of the PilQ pilotin PilF had no effect on localization. These results were confirmed in cells chemically blocked for cell division prior to outer membrane invagination. The hub protein FimV and a component of the polar organelle coordinator complex—PocA—were independently required for midcell recruitment of PilO and PilQ. Together, these data suggest an integrated, energy-efficient strategy for the targeting and preinstallation—rather than retrofitting—of the T4aP system into nascent poles, without the need for dedicated PG-remodeling enzymes. PMID:28143978

  9. ParA encoded on chromosome II of Deinococcus radiodurans binds to nucleoid and inhibits cell division in Escherichia coli

    Indian Academy of Sciences (India)

    Vijaya Kumar Charaka; Kruti P Mehta; H S Misra

    2013-09-01

    Bacterial genome segregation and cell division has been studied mostly in bacteria harbouring single circular chromosome and low-copy plasmids. Deinococcus radiodurans, a radiation-resistant bacterium, harbours multipartite genome system. Chromosome I encodes majority of the functions required for normal growth while other replicons encode mostly the proteins involved in secondary functions. Here, we report the characterization of putative P-loop ATPase (ParA2) encoded on chromosome II of D. radiodurans. Recombinant ParA2 was found to be a DNA-binding ATPase. E. coli cells expressing ParA2 showed cell division inhibition and mislocalization of FtsZ-YFP and those expressing ParA2-CFP showed multiple CFP foci formation on the nucleoid. Although, in trans expression of ParA2 failed to complement SlmA loss per se, it could induce unequal cell division in slmAminCDE double mutant. These results suggested that ParA2 is a nucleoid-binding protein, which could inhibits cell division in E. coli by affecting the correct localization of FtsZ and thereby cytokinesis. Helping slmAminCDE mutant to produce minicells, a phenotype associated with mutations in the `Min’ proteins, further indicated the possibility of ParA2 regulating cell division by bringing nucleoid compaction at the vicinity of septum growth.

  10. A pulse-chase strategy for EdU labelling assay is able to rapidly quantify cell division orientation.

    Science.gov (United States)

    Yin, Xiaofeng; Tsukaya, Hirokazu

    2016-09-01

    Measurement of the direction of cell division is an important, yet difficult, task to analyse how a plant organ acquires its final shape from an initially small group of cells. We introduce a method that rapidly and easily quantifies cell division direction and is applicable to all plant species. A pulse-chase strategy for 5-ethynyl-2'-deoxyuridine (EdU) labelling assay was established and was shown to be successful for leaves of Arabidopsis thaliana (Arabidopsis) and Juncus prismatocarpus. By optimization of the pulse and chase periods, most of the signals obtained were sets of daughter nuclei. For Arabidopsis, the optimal time was a 45-min pulse and a 7-h chase. For J. prismatocarpus, the optimal time was a 2-h pulse and a 13.5-h chase. The positions of the daughter nuclei were used to quantify cell division direction in the Arabidopsis leaf primordia. Overall, cell division along the proximal-distal axis was more frequent than along the medial-lateral axis. In petiole, major vein, minor vein and margin areas, the major cell division direction seemed to be coincident with the direction of auxin flow. The advantages of our method over the few methods used previously are discussed. We anticipate that it will provide opportunities to study plant development in the near future.

  11. ParA encoded on chromosome II of Deinococcus radiodurans binds to nucleoid and inhibits cell division in Escherichia coli.

    Science.gov (United States)

    Charaka, Vijaya Kumar; Mehta, Kruti P; Misra, H S

    2013-09-01

    Bacterial genome segregation and cell division has been studied mostly in bacteria harbouring single circular chromosome and low-copy plasmids. Deinococcus radiodurans, a radiation-resistant bacterium, harbours multipartite genome system. Chromosome I encodes majority of the functions required for normal growth while other replicons encode mostly the proteins involved in secondary functions. Here, we report the characterization of putative P-loop ATPase (ParA2) encoded on chromosome II of D. radiodurans. Recombinant ParA2 was found to be a DNA-binding ATPase. E. coli cells expressing ParA2 showed cell division inhibition and mislocalization of FtsZ-YFP and those expressing ParA2-CFP showed multiple CFP foci formation on the nucleoid. Although, in trans expression of ParA2 failed to complement SlmA loss per se, it could induce unequal cell division in slmAminCDE double mutant. These results suggested that ParA2 is a nucleoid-binding protein, which could inhibits cell division in E. coli by affecting the correct localization of FtsZ and thereby cytokinesis. Helping slmAminCDE mutant to produce minicells, a phenotype associated with mutations in the 'Min' proteins, further indicated the possibility of ParA2 regulating cell division by bringing nucleoid compaction at the vicinity of septum growth.

  12. Effect of capric, lauric and alpha-linolenic acids on the division time distributions of single cells of Staphylococcus aureus.

    Science.gov (United States)

    Sado Kamdem, S; Guerzoni, M E; Baranyi, J; Pin, C

    2008-11-30

    The effect of non-inhibitory concentrations of capric, lauric and alpha-linolenic acids (C10:0, C12:0 and C18:3 respectively) on the division time distribution of single cells of Staphylococcus aureus was evaluated at pH 7 and pH 5. The effect of the initial cell concentration on the lag time of growing cell populations was also assessed. The statistical properties of the division times (defined as the time interval from birth to next binary fission for a single cell) were studied using the method of Elfwing et al. [Elfwing, A., Le Marc, Y., Baranyi, J., Ballagi, A., 2004. Observing the growth and division of large number of individual bacteria using image analysis. Applied and Environmental Microbiology 70, 675-678]. The division times were significantly longer in the presence of free fatty acids than in the control. Shorter division intervals were detected at pH 7 than at pH 5 in the control experiment and in the presence of C10:0. However, both C12:0 and C18:3 slowed down the growth, regardless of the pH. The observed division time distributions were used to simulate growth curves from different inoculum sizes using the stochastic birth process described by Pin and Baranyi [Pin, C., Baranyi, J., 2006. Kinetics of single cells: observation and modelling of a stochastic process. Applied and Environmental Microbiology 72, 2163-2169]. The output of the simulation results were compared with observed data. The lag times fitted to simulated growth curves were in good agreement with those fitted to growth curves measured by plate counts. The averaged out effect of the population masked the effect of the free fatty acids and pH on the division times of single cells.

  13. Chordoma-derived cell line U-CH1-N recapitulates the biological properties of notochordal nucleus pulposus cells.

    Science.gov (United States)

    Fujita, Nobuyuki; Suzuki, Satoshi; Watanabe, Kota; Ishii, Ken; Watanabe, Ryuichi; Shimoda, Masayuki; Takubo, Keiyo; Tsuji, Takashi; Toyama, Yoshiaki; Miyamoto, Takeshi; Horiuchi, Keisuke; Nakamura, Masaya; Matsumoto, Morio

    2016-08-01

    Intervertebral disc degeneration proceeds with age and is one of the major causes of lumbar pain and degenerative lumbar spine diseases. However, studies in the field of intervertebral disc biology have been hampered by the lack of reliable cell lines that can be used for in vitro assays. In this study, we show that a chordoma-derived cell line U-CH1-N cells highly express the nucleus pulposus (NP) marker genes, including T (encodes T brachyury transcription factor), KRT19, and CD24. These observations were further confirmed by immunocytochemistry and flow cytometry. Reporter analyses showed that transcriptional activity of T was enhanced in U-CH1-N cells. Chondrogenic capacity of U-CH1-N cells was verified by evaluating the expression of extracellular matrix (ECM) genes and Alcian blue staining. Of note, we found that proliferation and synthesis of chondrogenic ECM proteins were largely dependent on T in U-CH1-N cells. In accordance, knockdown of the T transcripts suppressed the expression of PCNA, a gene essential for DNA replication, and SOX5 and SOX6, the master regulators of chondrogenesis. On the other hand, the CD24-silenced cells showed no reduction in the mRNA expression level of the chondrogenic ECM genes. These results suggest that U-CH1-N shares important biological properties with notochordal NP cells and that T plays crucial roles in maintaining the notochordal NP cell-like phenotype in this cell line. Taken together, our data indicate that U-CH1-N may serve as a useful tool in studying the biology of intervertebral disc. © 2016 The Authors. Journal of Orthopaedic Research Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 34:1341-1350, 2016.

  14. The three-dimensional architecture of the notochordal nucleus pulposus: novel observations on cell structures in the canine intervertebral disc.

    Science.gov (United States)

    Hunter, Christopher J; Matyas, John R; Duncan, Neil A

    2003-03-01

    Cells from the nucleus pulposus of young ( 5 years) non-chondrodystrophoid dogs were studied using routine histology, confocal laser scanning microscopy and transmission electron microscopy. The architecture of cell structures--from the tissue scale down to subcellular scale--was reported. Clusters of notochordal cells were observed in young nuclei pulposi, ranging from 10 to 426 cells each. These clusters resisted mechanical disruption and showed evidence of cell-cell signalling via gap junctions. Cells (30-40 microm in diameter) within the clusters had a physaliferous appearance, containing numerous large inclusions which ranged from 1 to 20 microm in diameter. The inclusions were surrounded by a dense actin cortex but were not contained by a lipid bilayer. The contents of the inclusions were determined not to be predominantly carbohydrate or neutral lipid as assessed by histochemical staining, but the exact composition of the contents remained uncertain. There were striking differences in the cell architecture of young vs. old nuclei pulposi, with a loss of both cell clusters and physaliferous cells during ageing. These observations demonstrate unique cell structures, which may influence our understanding of the differences between notochordal and chondrocytic cells in the nucleus pulposus. Such differences could have substantial impact upon how we think about development, degeneration and repair of the intervertebral disc.

  15. [On the effect of Chinese lacquer upon the cell division of root tip of Allium cepa].

    Science.gov (United States)

    Xing, H; Liang, W

    1997-01-01

    Chinese Lacquer, as a fine coating, has been studied and applied for thousands years. The allergic reaction in Chinese Lacquer on the human skin has also been known early. The reaction of Chinese Lacquer on mitosis of cell in plant meristem have not been reported yet and was carefully studied in this paper. The result showed that Chinese Lacquer induced severe abnormality of mitotic division in Allium cepa root tips. This was more obvious in the anaphase and telophase, especially in the former phase laggard chromosomes, chromosome bridges, acentric fragments and polypolar distribution could be seen frequently. A lot of polynuclear bodies were observed in the telophase. Therefore, we think that the Chinese Lacquer can be used as a plant cell mutagen, and suggest geneticists and physiologists to do more researches on the effects of Chinese Lacquer at the genetic variation, metabolism etc.

  16. Influence of hydroxyurea on cell divisions and microtubular cytoskeleton in Allium cepa root meristem

    Directory of Open Access Journals (Sweden)

    H. Q. Zhang

    2014-01-01

    Full Text Available In onion roots, hydroxyurea (HU causes a gradual depression of mitotic activity which ceases after 24-36 hrs. The effect is reversible; divisions begin after several hours of recovery and after 12-14 hrs about 90% cells undergo mitosis. Mitotic activity commences in the distal region of the apical meristem, and as a wave it spreads towards the apex. In the roots treated with HU for a short time, the tubulin immunofluorescence method reveals normal arrays of microtubules (MTs. After 36 hrs of HU treatment there are only cortical and endocytoplasmatic MTs. In the recovering roots, preprophase bands (PB mitotic spindles and phragmoplasts appear. Some PBs are split into two parallel rings. These abnormal PBs mostly occur in elongated cells. Apart from this, HU does not appear to have any significant influence on microtubular organization.

  17. Fruit illumination stimulates cell division but has no detectable effect on fruit size in tomato (Solanum lycopersicum).

    Science.gov (United States)

    Okello, Robert C O; Heuvelink, Ep; de Visser, Pieter H B; Lammers, Michiel; de Maagd, Ruud A; Marcelis, Leo F M; Struik, Paul C

    2015-05-01

    Light affects plant growth through assimilate availability and signals regulating development. The effects of light on growth of tomato fruit were studied using cuvettes with light-emitting diodes providing white, red or blue light to individual tomato trusses for different periods during daytime. Hypotheses tested were as follows: (1) light-grown fruits have stronger assimilate sinks than dark-grown fruits, and (2) responses depend on light treatment provided, and fruit development stage. Seven light treatments [dark, 12-h white, 24-h white, 24-h red and 24-h blue light, dark in the first 24 days after anthesis (DAA) followed by 24-h white light until breaker stage, and its reverse] were applied. Observations were made between anthesis and breaker stage at fruit, cell and gene levels. Fruit size and carbohydrate content did not respond to light treatments while cell division was strongly stimulated at the expense of cell expansion by light. The effects of light on cell number and volume were independent of the combination of light color and intensity. Increased cell division and decreased cell volume when fruits were grown in the presence of light were not clearly corroborated by the expression pattern of promoters and inhibitors of cell division and expansion analyzed in this study, implying a strong effect of posttranscriptional regulation. Results suggest the existence of a complex homeostatic regulatory system for fruit growth in which reduced cell division is compensated by enhanced cell expansion.

  18. High Antioxidant Activity Facilitates Maintenance of Cell Division in Leaves of Drought Tolerant Maize Hybrids

    Science.gov (United States)

    Avramova, Viktoriya; AbdElgawad, Hamada; Vasileva, Ivanina; Petrova, Alexandra S.; Holek, Anna; Mariën, Joachim; Asard, Han; Beemster, Gerrit T. S.

    2017-01-01

    We studied the impact of drought on growth regulation in leaves of 13 maize varieties with different drought sensitivity and geographic origins (Western Europe, Egypt, South Africa) and the inbred line B73. Combining kinematic analysis of the maize leaf growth zone with biochemical measurements at a high spatial resolution allowed us to examine the correlation between the regulation of the cellular processes cell division and elongation, and the molecular redox-regulation in response to drought. Moreover, we demonstrated differences in the response of the maize lines to mild and severe levels of water deficit. Kinematic analysis indicated that drought tolerant lines experienced less impact on leaf elongation rate due to a smaller reduction of cell production, which, in turn, was due to a smaller decrease of meristem size and number of cells in the leaf meristem. Clear differences in growth responses between the groups of lines with different geographic origin were observed in response to drought. The difference in drought tolerance between the Egyptian hybrids was significantly larger than between the European and South-African hybrids. Through biochemical analyses, we investigated whether antioxidant activity in the growth zone, contributes to the drought sensitivity differences. We used a hierarchical clustering to visualize the patterns of lipid peroxidation, H2O2 and antioxidant concentrations, and enzyme activities throughout the growth zone, in response to stress. The results showed that the lines with different geographic region used different molecular strategies to cope with the stress, with the Egyptian hybrids responding more at the metabolite level and African and the European hybrids at the enzyme level. However, drought tolerance correlated with both, higher antioxidant levels throughout the growth zone and higher activities of the redox-regulating enzymes CAT, POX, APX, and GR specifically in leaf meristems. These findings provide evidence for a link

  19. The adhesion GPCR latrophilin - a novel signaling cascade in oriented cell division and anterior-posterior polarity.

    Science.gov (United States)

    Winkler, Jana; Prömel, Simone

    2016-01-01

    Although several signaling pathways in oriented cell division have been well characterized such as delta/notch inductions or wnt/frizzled-based anterior-posterior polarity, there is strong evidence for additional signal pathways controlling early anterior-posterior polarity decisions. The homolog of the adhesion G protein-coupled receptor latrophilin, LAT-1 has been identified as a receptor essential for oriented cell division in an anterior-posterior direction of specific blastomeres in the early C. elegans embryo. We recently conducted a study aiming at clarifying the signals involved in LAT-1 function. We identified a Gs protein/adenylyl cyclase/cAMP pathway in vitro and demonstrated its physiological relevance in oriented cell division. By interaction with a Gs protein LAT-1 elevates cAMP levels. These data indicate that G-protein signaling in oriented cell division is not solely GPCR-independent. This commentary will discuss our findings in the context of the current knowledge of mechanisms controlling oriented cell division and anterior-posterior polarity. Further, we identify open questions which need to be addressed in the future.

  20. Identification of a Novel Nucleus Protein Involved in the Regulation of Urokinase in 95D Cells

    Institute of Scientific and Technical Information of China (English)

    Chang TONG; Li TAN; Ping LI; Yun-Song ZHU

    2005-01-01

    The urokinase-type plasminogen activator (uPA) plays an important role in cellular invasion.By using the downstream part of a 74 bp DNA region called the cooperation mediator (COM) of the uPA promoter as a bait sequence in the yeast one-hybrid screen, a gene called PBK1 was previously cloned from the cDNA library of the 95D lung cancer cell strain. In this study, the intracellular distribution of PBK1 was studied by using the transient transfection of pEGFP-C3-PBK1, and PBK1 was found to be localized in the nucleus. Co-transfection of pEGFP-C3-PBK1 and the deletion mutants of the pGL3-uPA promoter indicated that PBK1 can increase the uPA promoter activity by about 25% and this effect is uPA enhancer-dependent.Western blotting and Enzyme-linked immunoadsordent assay further confirmed that PBK1 can upregulate the expression of uPA. Our results suggest that PBK1 is involved in the regulation of uPA expression, which might provide a new clue to further understanding the regulation mechanism of uPA expression.

  1. Inflammatory Kinetics and Efficacy of Anti-inflammatory Treatments on Human Nucleus Pulposus Cells

    Science.gov (United States)

    Walter, Benjamin A; Purmessur, Devina; Likhitpanichkul, Morakot; Weinberg, Alan; Cho, Samuel K.; Qureshi, Sheeraz A.; Hecht, Andrew C.; Iatridis, James C.

    2015-01-01

    Study Design Human nucleus pulposus (NP) cell culture study investigating response to tumor necrosis factor-α (TNFα), effectiveness of clinically available anti-inflammatory drugs, and interactions between pro-inflammatory cytokines. Objective To characterize the kinetic response of pro-inflammatory cytokines released by human NP cells to TNFα stimulation and the effectiveness of multiple anti-inflammatories with 3 sub-studies: Timecourse, Same-time blocking, Delayed blocking. Summary of Background Data Chronic inflammation is a key component of painful intervertebral disc (IVD) degeneration. Improved efficacy of anti-inflammatories requires better understanding of how quickly NP cells produce pro-inflammatory cytokines and which pro-inflammatory mediators are most therapeutically advantageous to target. Methods Degenerated human NP cells (n=10) were cultured in alginate with or without TNFα (10ng/mL). Cells were incubated with one of four anti-inflammatories (anti-IL-6 receptor/atlizumab, IL-1 receptor anatagonist, anti-TNFα/infliximab and sodium pentosan polysulfate/PPS) in two blocking-studies designed to determine how intervention timing influences drug efficacy. Cell viability, protein and gene expression for IL-1β, IL-6 & IL-8 were assessed. Results Timecourse: TNFα substantially increased the amount of IL-6, IL-8 & IL-1β, with IL-1β and IL-8 reaching equilibrium within ~72 hours (IL-1β: 111±40pg/mL, IL-8: 8478±957pg/mL), and IL-6 not reaching steady state after 144 hours (1570±435 pg/mL). Anti-TNFα treatment was most effective at reducing the expression of all cytokines measured when added at the same time as TNFα stimulation. Similar trends were observed when drugs were added 72 hours after TNFα stimulation, however, no anti-inflammatories significantly reduced cytokine levels compared to TNF control. Conclusion IL-1β, IL-6 and IL-8 were expressed at different rates and magnitudes suggesting different roles for these cytokines in disease

  2. Arabidopsis CAP regulates the actin cytoskeleton necessary for plant cell elongation and division.

    Science.gov (United States)

    Barrero, Roberto A; Umeda, Masaaki; Yamamura, Saburo; Uchimiya, Hirofumi

    2002-01-01

    An Arabidopsis cDNA (AtCAP1) that encodes a predicted protein of 476 amino acids highly homologous with the yeast cyclase-associated protein (CAP) was isolated. Expression of AtCAP1 in the budding yeast CAP mutant was able to rescue defects such as abnormal cell morphology and random budding pattern. The C-terminal domain, 158 amino acids of AtCAP1 possessing in vitro actin binding activity, was needed for the regulation of cytoskeleton-related defects of yeast. Transgenic plants overexpressing AtCAP1 under the regulation of a glucocorticoid-inducible promoter showed different levels of AtCAP1 accumulation related to the extent of growth abnormalities, in particular size reduction of leaves as well as petioles. Morphological alterations in leaves were attributable to decreased cell size and cell number in both epidermal and mesophyll cells. Tobacco suspension-cultured cells (Bright Yellow 2) overexpressing AtCAP1 exhibited defects in actin filaments and were unable to undergo mitosis. Furthermore, an immunoprecipitation experiment suggested that AtCAP1 interacted with actin in vivo. Therefore, AtCAP1 may play a functional role in actin cytoskeleton networking that is essential for proper cell elongation and division.

  3. Requirement of cell nucleus for Sindbis virus replication in cultured Aedes albopictus cells.

    Science.gov (United States)

    Erwin, C; Brown, D T

    1983-02-01

    The ability of Sindbis virus to grow in enucleated BHK-21 (vertebrate) and Aedes albopictus (invertebrate) cells was tested to determine the dependence of this virus upon nuclear function in these two phylogenetically unrelated hosts. Although both cell types could be demonstrated to produce viable cytoplasts (enucleated cells) which produced virus-specific antigen subsequent to infection. BHK cytoplasts produced a significant number of progeny virions, whereas mosquito cytoplasts did not. The production of vesicular stomatitis virus in mosquito cells was not significantly reduced by enucleation. That such a host function was not essential for vesicular stomatitis virus growth in insect cells is supported by the observation that the production of this virus by mosquito cells is not actinomycin D sensitive. This result agrees with a previously published report in which it was shown that Sindbis virus maturation in invertebrate cells is inhibited by actinomycin D, indicating a possible requirement for host cell nuclear function (Scheefers-Borchel et al., Virology, 110:292-301, 1981).

  4. Mechanisms of organelle division and inheritance and their implications regarding the origin of eukaryotic cells

    OpenAIRE

    Kuroiwa, Tsuneyoshi

    2010-01-01

    Mitochondria and plastids have their own DNAs and are regarded as descendants of endosymbiotic prokaryotes. Organellar DNAs are not naked in vivo but are associated with basic proteins to form DNA-protein complexes (called organelle nuclei). The concept of organelle nuclei provides a new approach to explain the origin, division, and inheritance of organelles. Organelles divide using organelle division rings (machineries) after organelle-nuclear division. Organelle division machineries are a c...

  5. Microcystin quota, cell division and microcystin net production of precultured Microcystis aeruginosa CYA 228 (Chroococcales, Cyanophyceae) under field conditions

    DEFF Research Database (Denmark)

    Lyck, S.; Christoffersen, K.

    2003-01-01

    The relationship between the specific cell division rate (mu(c)), the specific microcystin (mcyst) production rate (mu(mcyst)) and the cellular content of mcyst (Q(mcyst)) was investigated during growth of Microcystis aeruginosa strain CYA 228 cells in the field (microcosms), and the results were...

  6. Cortical excitatory neurons become protected from cell division during neurogenesis in an Rb family-dependent manner.

    Science.gov (United States)

    Oshikawa, Mio; Okada, Kei; Nakajima, Kazunori; Ajioka, Itsuki

    2013-06-01

    Cell cycle dysregulation leads to abnormal proliferation and cell death in a context-specific manner. Cell cycle progression driven via the Rb pathway forces neurons to undergo S-phase, resulting in cell death associated with the progression of neuronal degeneration. Nevertheless, some Rb- and Rb family (Rb, p107 and p130)-deficient differentiating neurons can proliferate and form tumors. Here, we found in mouse that differentiating cerebral cortical excitatory neurons underwent S-phase progression but not cell division after acute Rb family inactivation in differentiating neurons. However, the differentiating neurons underwent cell division and proliferated when Rb family members were inactivated in cortical progenitors. Differentiating neurons generated from Rb(-/-); p107(-/-); p130(-/-) (Rb-TKO) progenitors, but not acutely inactivated Rb-TKO differentiating neurons, activated the DNA double-strand break (DSB) repair pathway without increasing trimethylation at lysine 20 of histone H4 (H4K20), which has a role in protection against DNA damage. The activation of the DSB repair pathway was essential for the cell division of Rb-TKO differentiating neurons. These results suggest that newly born cortical neurons from progenitors become epigenetically protected from DNA damage and cell division in an Rb family-dependent manner.

  7. Absence of nucleoid occlusion effector Noc impairs formation of orthogonal FtsZ rings during Staphylococcus aureus cell division.

    Science.gov (United States)

    Veiga, Helena; Jorge, Ana M; Pinho, Mariana G

    2011-06-01

    The Gram-positive pathogen Staphylococcus aureus divides by synthesizing the septum in three orthogonal planes over three consecutive division cycles. This process has to be tightly coordinated with chromosome segregation to avoid bisection of the nucleoid by the septum. Here we show that deletion of the nucleoid occlusion effector Noc in S. aureus results in the formation of Z-rings over the nucleoid, as well as in DNA breaks, indicating that Noc has an important role as an antiguillotine checkpoint that prevents septa from forming over the DNA. Furthermore, Noc deleted cells show multiple Z-rings which are no longer placed in perpendicular planes. We propose that the axis of chromosome segregation has a role in determining the placement of the division septum. This is achieved via the action of Noc which restricts the placement of the division septum to one of an infinite number of potential division planes that exist in S. aureus.

  8. Neuronal cell death in the arcuate nucleus of the medulla oblongata in stillbirth.

    Science.gov (United States)

    Folkerth, Rebecca D; Zanoni, Sallie; Andiman, Sarah E; Billiards, Saraid S

    2008-02-01

    The hypothesis that unexplained stillbirth arises in a similar manner as the sudden infant death syndrome (SIDS) is based in part on shared neuropathologic features between the two entities, including hypoxic-ischemic lesions such as white matter and brainstem gliosis, as well as aplasia or hypoplasia of the arcuate nucleus on the ventral surface of the medulla. The arcuate nucleus is the putative homologue of the respiratory chemosensory region at the ventral medullary surface in animals that is involved in central chemosensitivity. To determine arcuate nucleus pathology in stillbirth, and its co-occurrence with evidence of hypoxia-ischemia, we reviewed brain specimens from the archives of our hospitals from 22 consecutive stillbirths from 22 to 41 gestational weeks. Explained causes of death (n=17) included nuchal cord, acute chorioamnionitis, placental abruption, and fetal glomerulosclerosis; 5 cases were unexplained. In 12 brains, we observed nuclear karyorrhexis and/or pyknosis with cytoplasmic hypereosinophilia in neurons in the arcuate nucleus in both explained (n=8) and unexplained (n=4) cases (54.5% of total cases). Three additional cases had arcuate aplasia (n=1) or hypoplasia (n=2) (13.6% of total cases); one of the latter cases also had neuronal necrosis in the hypoplastic arcuate. The degree of gliosis in the region of the arcuate nucleus was variable across all cases, without statistically significant differences between groups with and without arcuate nucleus necrosis. Other lesions in association with (n=14) and without (n=8) arcuate nucleus abnormalities were diffuse cerebral white matter gliosis, periventricular leukomalacia (PVL), and neuronal necrosis in the hippocampus, basal ganglia, thalamus, basis pontis, and brainstem tegmentum. In 16/20 (80.0%) cases (with or without histologic necrosis of the arcuate), immunostaining with caspase-3 demonstrated positive neurons. Our findings suggest that neuronal pathology in the arcuate nucleus may be

  9. Flow cytometric quantification of T cell proliferation and division kinetics in woodchuck model of hepatitis B.

    Science.gov (United States)

    Gujar, Shashi A; Michalak, Tomasz I

    2005-01-01

    Woodchucks infected with woodchuck hepatitis virus (WHV) represent the closest natural animal model to study the immunopathogenesis of liver injury caused by essentially noncytopathic, highly human specific hepatitis B virus (HBV). The importance of antiviral T cell response in induction of hepatitis and in control of HBV replication has been demonstrated. However, the understanding of how these responses contribute to the development of different immunomorphological forms of liver disease and their outcomes remain elusive. In this study, we established and standardized a flow cytometry assay using peripheral blood mononuclear cells labeled with carboxyfluorescein diacetate succinimidyl ester (CFSE) to assess WHV-specific and mitogen-driven T lymphocyte proliferative responses in woodchucks. The assay is of significantly greater sensitivity than the adenine incorporation assay currently used when applied to measure either WHV-specific T cell responses in acute (P measuring cell division rates. The study shows that woodchuck PBMC labeled with CFSE exhibit light scatter and fluorescence profiles compatible to those of human PBMC, allowing quantitation and deconvolution of the flow cytometric data by applying the existing analytical softwares. The availability of this novel assay should facilitate a more precise and comprehensive evaluation of hepadnavirus-specific and generalized T cell responses in experimental WHV hepatitis.

  10. Design, synthesis and antibacterial activity of cinnamaldehyde derivatives as inhibitors of the bacterial cell division protein FtsZ.

    Science.gov (United States)

    Li, Xin; Sheng, Juzheng; Huang, Guihua; Ma, Ruixin; Yin, Fengxin; Song, Di; Zhao, Can; Ma, Shutao

    2015-06-05

    In an attempt to discover potential antibacterial agents against the increasing bacterial resistance, novel cinnamaldehyde derivatives as FtsZ inhibitors were designed, synthesized and evaluated for their antibacterial activity against nine significant pathogens using broth microdilution method, and their cell division inhibitory activity against four representative strains. In the in vitro antibacterial activity, the newly synthesized compounds generally displayed better efficacy against Staphylococcus aureus ATCC25923 than the others. In particular, compounds 3, 8 and 10 exerted superior or comparable activity to all the reference drugs. In the cell division inhibitory activity, all the compounds showed the same trend as their in vitro antibacterial activity, exhibiting better activity against S. aureus ATCC25923 than the other strains. Additionally, compounds 3, 6, 7 and 8 displayed potent cell division inhibitory activity with an MIC value of below 1 μg/mL, over 256-fold better than all the reference drugs.

  11. The planar cell polarity protein Strabismus promotes Pins anterior localization during asymmetric division of sensory organ precursor cells in Drosophila.

    Science.gov (United States)

    Bellaïche, Yohanns; Beaudoin-Massiani, Olivia; Stuttem, Isabella; Schweisguth, François

    2004-01-01

    Cell fate diversity is generated in part by the unequal segregation of cell-fate determinants during asymmetric cell division. In the Drosophila bristle lineage, the sensory organ precursor (pI) cell is polarized along the anteroposterior (AP) axis by Frizzled (Fz) receptor signaling. We show here that Fz localizes at the posterior apical cortex of the pI cell prior to mitosis, whereas Strabismus (Stbm) and Prickle (Pk), which are also required for AP polarization of the pI cell, co-localize at the anterior apical cortex. Thus, asymmetric localization of Fz, Stbm and Pk define two opposite cortical domains prior to mitosis of the pI cell. At mitosis, Stbm forms an anterior crescent that overlaps with the distribution of Partner of Inscuteable (Pins) and Discs-large (Dlg), two components of the anterior Dlg-Pins-Galphai complex that regulates the localization of cell-fate determinants. At prophase, Stbm promotes the anterior localization of Pins. By contrast, Dishevelled (Dsh) acts antagonistically to Stbm by excluding Pins from the posterior cortex. We propose that the Stbm-dependent recruitment of Pins at the anterior cortex of the pI cell is a novel read-out of planar cell polarity.

  12. Interaction of Mouse Pem Protein and Cell Division Cycle 37 Homolog

    Institute of Scientific and Technical Information of China (English)

    Fen GUO; Yue-Qin LI; Shi-Qian LI; Zhi-Wen LUO; Xin ZHANG; Dong-Sheng TANG; Tian-Hong ZHOU

    2005-01-01

    Mouse Pem, a homeobox gene, encodes a protein consisting of 210 amino acid residues. To study the function of mouse Pem protein, we used the yeast two-hybrid system to screen the library of 7-day mouse embryo with full-length mouse Pem eDNA. Fifty-two colonies were obtained after 1.57×108 colonies were screened by nutrition limitation and β-galactosidase assay. Seven individual insert fragments were obtained from the library, and three of them were identified, one of which was confirmed to be the cell division cycle 37 (Cdc37) homolog gene by sequencing. The interaction between mouse Pem and Cdc37homolog was then confirmed by glutathione S-transferase pull-down assay, and the possible interaction model was suggested.

  13. Studies on the cortical morphogenesis during cell division in Halteria grandinella (Muller, 1773) (Ciliophora, Oligotrichida)

    Science.gov (United States)

    Song, Weibo

    1993-06-01

    Morphogenesis during cell division was investigated in oligotrichous ciliate, Halteria grandinella utilizing protargol impregnated specimens. The cortical morphogenetical pattern of Halteria grandinella is generally similar to that given by Fauré-Fremiet. The proter inherits the parental adoral zone of membranelles (AZM) apparently unchanged; in the opisthe the oral primordium develops de novo from a single. AZM-anlage; somatic cirri for both the proter and opisthe are separately differentiated from 10 (seldom 9) cirral primordia that originate de novo from 10 latitudinal developmental analagen. The anlage of paroral membrane of opisthe forms just to the right of the posterior end of the oral primordium. Each streak of cirral primordia develops 4 groups of basal body pairs: both of the anterior two consist of only one pair of basal bodies, on the contrary, each of the last two groups has 2 basal body pairs.

  14. Mesenchymal stem cells regulate mechanical properties of human degenerated nucleus pulposus cells through SDF-1/CXCR4/AKT axis.

    Science.gov (United States)

    Liu, Ming-Han; Bian, Bai-Shi-Jiao; Cui, Xiang; Liu, Lan-Tao; Liu, Huan; Huang, Bo; Cui, You-Hong; Bian, Xiu-Wu; Zhou, Yue

    2016-08-01

    Transplantation of mesenchymal stem cells (MSCs) into the degenerated intervertebral disc (IVD) has shown promise for decelerating or arresting IVD degeneration. Cellular mechanical properties play crucial roles in regulating cell-matrix interactions, potentially reflecting specific changes that occur based on cellular phenotype and behavior. However, the effect of co-culturing of MSCs with nucleus pulposus cells (NPCs) on the mechanical properties of NPCs remains unknown. In our study, we demonstrated that co-culture of degenerated NPCs with MSCs resulted in significantly decreased mechanical moduli (elastic modulus, relaxed modulus, and instantaneous modulus) and increased biological activity (proliferation and expression of matrix genes) in degenerated NPCs, but not normal NPCs. SDF-1, CXCR4 ligand, was highly expressed in MSCs when co-cultured with degenerated NPCs. Inhibition of SDF-1 using CXCR4 antagonist AMD3100 or knocking-down CXCR4 in degenerated NPCs abolished the MSCs-induced decrease in the mechanical moduli and increased biological activity of degenerated NPCs, suggesting a crucial role for SDF-1/CXCR4 signaling. AKT and FAK inhibition attenuated the MSCs- or SDF-1-induced decrease in the mechanical moduli of degenerated NPCs. In conclusion, it was demonstrated in vitro that MSCs regulate the mechanical properties of degenerated NPCs through SDF-1/CXCR4/AKT signaling. These findings highlight a possible mechanical mechanism for MSCs-induced modulation with degenerated NPCs, which may be applicable to MSCs-based therapy for disc degeneration.

  15. Rate maintenance of cell division in Escherichia coli B/r: analysis of a simple nutritional shift-down.

    OpenAIRE

    Zaritsky, A; Helmstetter, C E

    1992-01-01

    A competitive (nonmetabolizable) inhibitor of glucose uptake, alpha-methylglucoside, was used to limit the growth of Escherichia coli. Cell division during such a nutritional shift-down was studied in batch cultures and with the "baby-machine" technique. Following a brief delay, the rate of division was maintained for 60 to 70 min in batch cultures and for an extended period in the baby machine. Decreases in cell size were due, in part, to a possible reduction in the mass per chromosome origi...

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

    OpenAIRE

    Fenton, Andrew K.; Gerdes, Kenn

    2013-01-01

    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...

  17. Can notochordal cells promote bone marrow stromal cell potential for nucleus pulposus enrichment? A simplified in vitro system.

    Science.gov (United States)

    Potier, Esther; Ito, Keita

    2014-12-01

    Bone marrow stromal cells (BMSCs) have shown promising potential to stop intervertebral disc degeneration in several animal models. In order to restore a healthy state, though, this potential should be further stimulated. Notochordal cells (NCs), influential in disc development, have been shown to stimulate BMSC differentiation, but it is unclear how this effect will translate in an environment where resident disc cells (nucleus pulposus cells [NPCs]) could also influence BMSCs. The goal of this study was, therefore, to evaluate the effects of NCs on BMSCs when cocultured with NPCs, in a simplified 3D in vitro system. Bovine BMSCs and NPCs were mixed (Mix) and seeded into alginate beads. Using culture inserts, the Mix was then cocultured with porcine NCs (alginate beads) and compared to coculture with empty beads or porcine skin fibroblasts (SFs, alginate beads). NPCs alone were also cocultured with NCs, and BMSCs alone cultured under chondrogenic conditions. The effects of coculture conditions on cell viability, matrix production (proteoglycan and collagen), and gene expression of disc markers (aggrecan, type II collagen, and SOX9) were assessed after 4 weeks of culture. The NC phenotype and gene expression profile were also analyzed. Coculture with NCs did not significantly influence cell viability, proteoglycan production, or disc marker gene expression of the Mix. When compared to NPCs, the Mix produced the same amount of proteoglycan and displayed a higher expression of disc marker, indicating a stimulation of the BMSCs (and/or NPCs) in the Mix. Additionally, during the 4 weeks of culture, the NC phenotype changed drastically (morphology, gene expression profile). These results show that NCs might not be as stimulatory for BMSCs in an NPC-rich environment, as believed from individual cultures. This absence of effects could be explained by a mild stimulation provided by (de)differentiating NCs and the costimulation of BMSCs and NPCs by each other.

  18. 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.

  19. Regulation of transcription of cell division genes in the Escherichia coli dcw cluster.

    Science.gov (United States)

    Vicente, M; Gomez, M J; Ayala, J A

    1998-04-01

    The Escherichia coli dcw cluster contains cell division genes, such as the phylogenetically ubiquitous ftsZ, and genes involved in peptidoglycan synthesis. Transcription in the cluster proceeds in the same direction as the progress of the replication fork along the chromosome. Regulation is exerted at the transcriptional and post-transcriptional levels. The absence of transcriptional termination signals may, in principle, allow extension of the transcripts initiated at the up-stream promoter (mraZ1p) even to the furthest down-stream gene (envA). Complementation tests suggest that they extend into ftsW in the central part of the cluster. In addition, the cluster contains other promoters individually regulated by cis- and trans-acting signals. Dissociation of the expression of the ftsZ gene, located after ftsQ and A near the 3' end of the cluster, from its natural regulatory signals leads to an alteration in the physiology of cell division. The complexities observed in the regulation of gene expression in the cluster may then have an important biological role. Among them, LexA-binding SOS boxes have been found at the 5' end of the cluster, preceding promoters which direct the expression of ftsI (coding for PBP3, the penicillin-binding protein involved in septum formation). A gearbox promoter, ftsQ1p, forms part of the signals regulating the transcription of ftsQ, A and Z. It is an inversely growth-dependent mechanism driven by RNA polymerase containing sigma s, the factor involved in the expression of stationary phase-specific genes. Although the dcw cluster is conserved to a different extent in a variety of bacteria, the regulation of gene expression, the presence or absence of individual genes, and even the essentiality of some of them, show variations in the phylogenetic scale which may reflect adaptation to specific life cycles.

  20. κ-Opioid receptor in the nucleus is a novel prognostic factor of esophageal squamous cell carcinoma.

    Science.gov (United States)

    Zhang, Yong-Fa; Xu, Qing-Xia; Liao, Lian-Di; Xu, Xiu-E; Wu, Jian-Yi; Shen, Jian; Wu, Zhi-Yong; Shen, Jin-Hui; Li, En-Min; Xu, Li-Yan

    2013-09-01

    Opioid receptors, members of the G-protein-coupled receptor superfamily, appear to be involved in cancer progression. However, the expression and significance of opioid receptors in esophageal squamous cell carcinoma (ESCC) remain unclear. In this study, we demonstrated by flow cytometry that μ, δ, and κ-opioid receptors (MOR, DOR, and KOR) are expressed to various degrees in ESCC cell lines. The KOR protein was further examined by several methods in ESCC cell lines and tissues. Immunocytochemical staining localized KOR to the cell membrane in KYSE180 cells and the nucleus in EC109 cells, whereas no signal or weak staining of the cytoplasm was observed in KYSE150 cells. The expression of KOR was confirmed in ESCC cells by Western blotting. Furthermore, immunohistochemistry staining showed that KOR was up-regulated in ESCC tissues compared with nontumorous esophageal epithelium (P = .004, χ(2) test). Moreover, high nuclear KOR expression was significantly correlated with lymph node metastasis in 256 ESCC cases (R = 0.144; P = .030, Kendall τB test). Patients with high nuclear KOR expression in ESCC had a significantly poorer prognosis (P = .001, log-rank test). Multivariate Cox analysis revealed that KOR in the nucleus was an independent prognostic factor (hazard ratio, 1.789; 95% confidence interval, 1.177-2.720; P = .006). Our results suggest that KOR is involved in the carcinogenesis or progression of ESCC and that nuclear KOR may be indicative of prognosis.

  1. Roles of Cell Division and Gene Transcription in the Methylation of CpG Islands

    Science.gov (United States)

    Bender, Christina M.; Gonzalgo, Mark L.; Gonzales, Felicidad A.; Nguyen, Carvell T.; Robertson, Keith D.; Jones, Peter A.

    1999-01-01

    De novo methylation of CpG islands within the promoters of eukaryotic genes is often associated with their transcriptional repression, yet the methylation of CpG islands located downstream of promoters does not block transcription. We investigated the kinetics of mRNA induction, demethylation, and remethylation of the p16 promoter and second-exon CpG islands in T24 cells after 5-aza-2′-deoxycytidine (5-Aza-CdR) treatment to explore the relationship between CpG island methylation and gene transcription. The rates of remethylation of both CpG islands were associated with time but not with the rate of cell division, and remethylation of the p16 exon 2 CpG island occurred at a higher rate than that of the p16 promoter. We also examined the relationship between the remethylation of coding sequence CpG islands and gene transcription. The kinetics of remethylation of the p16 exon 2, PAX-6 exon 5, c-ABL exon 11, and MYF-3 exon 3 loci were examined following 5-Aza-CdR treatment because these genes contain exonic CpG islands which are hypermethylated in T24 cells. Remethylation occurred most rapidly in the p16, PAX-6, and c-ABL genes, shown to be transcribed prior to drug treatment. These regions also exhibited higher levels of remethylation in single-cell clones and subclones derived from 5-Aza-CdR-treated T24 cells. Our data suggest that de novo methylation is not restricted to the S phase of the cell cycle and that transcription through CpG islands does not inhibit their remethylation. PMID:10490608

  2. Integrin-mediated interactions with extracellular matrix proteins for nucleus pulposus cells of the human intervertebral disc.

    Science.gov (United States)

    Bridgen, D T; Gilchrist, C L; Richardson, W J; Isaacs, R E; Brown, C R; Yang, K L; Chen, J; Setton, L A

    2013-10-01

    The extracellular matrix (ECM) of the human intervertebral disc is rich in molecules that interact with cells through integrin-mediated attachments. Porcine nucleus pulposus (NP) cells have been shown to interact with laminin (LM) isoforms LM-111 and LM-511 through select integrins that regulate biosynthesis and cell attachment. Since human NP cells lose many phenotypic characteristics with age, attachment and interaction with the ECM may be altered. Expression of LM-binding integrins was quantified for human NP cells using flow cytometry. The cell-ECM attachment mechanism was determined by quantifying cell attachment to LM-111, LM-511, or type II collagen after functionally blocking specific integrin subunits. Human NP cells express integrins β1, α3, and α5, with over 70% of cells positive for each subunit. Blocking subunit β1 inhibited NP cell attachment to all substrates. Blocking subunits α1, α2, α3, and α5 simultaneously, but not individually, inhibits NP cell attachment to laminins. While integrin α6β1 mediated porcine NP cell attachment to LM-111, we found integrins α3, α5, and β1 instead contributed to human NP cell attachment. These findings identify integrin subunits that may mediate interactions with the ECM for human NP cells and could be used to promote cell attachment, survival, and biosynthesis in cell-based therapeutics.

  3. Novel role of phosphorylation-dependent interaction between FtsZ and FipA in mycobacterial cell division.

    Directory of Open Access Journals (Sweden)

    Kamakshi Sureka

    Full Text Available The bacterial divisome is a multiprotein complex. Specific protein-protein interactions specify whether cell division occurs optimally, or whether division is arrested. Little is known about these protein-protein interactions and their regulation in mycobacteria. We have investigated the interrelationship between the products of the Mycobacterium tuberculosis gene cluster Rv0014c-Rv0019c, namely PknA (encoded by Rv0014c and FtsZ-interacting protein A, FipA (encoded by Rv0019c and the products of the division cell wall (dcw cluster, namely FtsZ and FtsQ. M. smegmatis strains depleted in components of the two gene clusters have been complemented with orthologs of the respective genes of M. tuberculosis. Here we identify FipA as an interacting partner of FtsZ and FtsQ and establish that PknA-dependent phosphorylation of FipA on T77 and FtsZ on T343 is required for cell division under oxidative stress. A fipA knockout strain of M. smegmatis is less capable of withstanding oxidative stress than the wild type and showed elongation of cells due to a defect in septum formation. Localization of FtsQ, FtsZ and FipA at mid-cell was also compromised. Growth and survival defects under oxidative stress could be functionally complemented by fipA of M. tuberculosis but not its T77A mutant. Merodiploid strains of M. smegmatis expressing the FtsZ(T343A showed inhibition of FtsZ-FipA interaction and Z ring formation under oxidative stress. Knockdown of FipA led to elongation of M. tuberculosis cells grown in macrophages and reduced intramacrophage growth. These data reveal a novel role of phosphorylation-dependent protein-protein interactions involving FipA, in the sustenance of mycobacterial cell division under oxidative stress.

  4. Quantitative phase imaging of cell division in yeast cells and E.coli using digital holographic microscopy

    Science.gov (United States)

    Pandiyan, Vimal Prabhu; John, Renu

    2015-12-01

    Digital holographic microscope (DHM) is an emerging quantitative phase imaging technique with unique imaging scales and resolutions leading to multitude of applications. DHM is promising as a novel investigational and applied tool for cell imaging, studying the morphology and real time dynamics of cells and a number of related applications. The use of numerical propagation and computational digital optics offer unique flexibility to tune the depth of focus, and compensate for image aberrations. In this work, we report imaging the dynamics of cell division in E.coli and yeast cells using a DHM platform. We demonstrate 3-D and depth imaging as well as reconstruction of phase profiles of E.coli and yeast cells using the system. We record a digital hologram of E.coli and yeast cells and reconstruct the image using Fresnel propagation algorithm. We also use aberration compensation algorithms for correcting the aberrations that are introduced by the microscope objective in the object path using linear least square fitting techniques. This work demonstrates the strong potential of a DHM platform in 3-D live cell imaging, fast clinical quantifications and pathological applications.

  5. Akt is transferred to the nucleus of cells treated with apoptin, and it participates in apoptin-induced cell death

    DEFF Research Database (Denmark)

    Bay, GH; Kroczak, TJ; Ande, SR;

    2007-01-01

    . Downstream of PI3-K, Akt is activated and translocated to the nucleus together with apoptin. Direct interaction between apoptin and Akt is documented. Co-expression of nuclear Akt significantly potentiates cell death induced by apoptin. Thus, apoptin-facilitated nuclear Akt, in contrast to when in its...

  6. Structure-function analysis of the extracellular domain of the pneumococcal cell division site positioning protein MapZ.

    Science.gov (United States)

    Manuse, Sylvie; Jean, Nicolas L; Guinot, Mégane; Lavergne, Jean-Pierre; Laguri, Cédric; Bougault, Catherine M; VanNieuwenhze, Michael S; Grangeasse, Christophe; Simorre, Jean-Pierre

    2016-06-27

    Accurate placement of the bacterial division site is a prerequisite for the generation of two viable and identical daughter cells. In Streptococcus pneumoniae, the positive regulatory mechanism involving the membrane protein MapZ positions precisely the conserved cell division protein FtsZ at the cell centre. Here we characterize the structure of the extracellular domain of MapZ and show that it displays a bi-modular structure composed of two subdomains separated by a flexible serine-rich linker. We further demonstrate in vivo that the N-terminal subdomain serves as a pedestal for the C-terminal subdomain, which determines the ability of MapZ to mark the division site. The C-terminal subdomain displays a patch of conserved amino acids and we show that this patch defines a structural motif crucial for MapZ function. Altogether, this structure-function analysis of MapZ provides the first molecular characterization of a positive regulatory process of bacterial cell division.

  7. Structure-function analysis of the extracellular domain of the pneumococcal cell division site positioning protein MapZ

    Science.gov (United States)

    Manuse, Sylvie; Jean, Nicolas L.; Guinot, Mégane; Lavergne, Jean-Pierre; Laguri, Cédric; Bougault, Catherine M.; Vannieuwenhze, Michael S.; Grangeasse, Christophe; Simorre, Jean-Pierre

    2016-06-01

    Accurate placement of the bacterial division site is a prerequisite for the generation of two viable and identical daughter cells. In Streptococcus pneumoniae, the positive regulatory mechanism involving the membrane protein MapZ positions precisely the conserved cell division protein FtsZ at the cell centre. Here we characterize the structure of the extracellular domain of MapZ and show that it displays a bi-modular structure composed of two subdomains separated by a flexible serine-rich linker. We further demonstrate in vivo that the N-terminal subdomain serves as a pedestal for the C-terminal subdomain, which determines the ability of MapZ to mark the division site. The C-terminal subdomain displays a patch of conserved amino acids and we show that this patch defines a structural motif crucial for MapZ function. Altogether, this structure-function analysis of MapZ provides the first molecular characterization of a positive regulatory process of bacterial cell division.

  8. Evolution of the chloroplast division machinery

    Institute of Scientific and Technical Information of China (English)

    Hongbo GAO; Fuli GAO

    2011-01-01

    Chloroplasts are photosynthetic organelles derived from endosymbiotic cyanobacteria during evolution.Dramatic changes occurred during the process of the formation and evolution of chloroplasts,including the large-scale gene transfer from chloroplast to nucleus.However,there are still many essential characters remaining.For the chloroplast division machinery,FtsZ proteins,Ftn2,SulA and part of the division site positioning system- MinD and MinE are still conserved.New or at least partially new proteins,such as FtsZ family proteins FtsZl and ARC3,ARC6H,ARC5,PDV1,PDV2 and MCD1,were introduced for the division of chloroplasts during evolution.Some bacterial cell division proteins,such as FtsA,MreB,Ftn6,FtsW and Ftsl,probably lost their function or were gradually lost.Thus,the chloroplast division machinery is a dynamically evolving structure with both conservation and innovation.

  9. Nuclear envelope dynamics during plant cell division suggest common mechanisms between kingdoms.

    Science.gov (United States)

    Graumann, Katja; Evans, David E

    2011-05-01

    Behaviour of the NE (nuclear envelope) during open mitosis has been explored extensively in metazoans, but lack of native markers has limited similar investigations in plants. In the present study, carried out using living synchronized tobacco BY-2 suspension cultures, the non-functional NE marker LBR (lamin B receptor)-GFP (green fluorescent protein) and two native, functional NE proteins, AtSUN1 [Arapidopsis thaliana SUN (Sad1/UNC84) 1] and AtSUN2, we provide evidence that the ER (endoplasmic reticulum)-retention theory for NE membranes is applicable in plants. We also observe two apparently unique plant features: location of the NE-membrane components in close proximity to chromatin throughout division, and spatially distinct reformation of the NE commencing at the chromatin surface facing the spindle poles and concluding at the surface facing the cell plate. Mobility of the proteins was investigated in the interphase NE, during NE breakdown and reformation, in the spindle membranes and the cell plate. A role for AtSUN2 in nuclear envelope breakdown is suggested.

  10. Expression of a begomoviral DNAβ gene in transgenic Nicotiana plants induced abnormal cell division

    Institute of Scientific and Technical Information of China (English)

    CUI Xiao-feng; LI Yun-qin; HU Dong-wei; ZHOU Xue-ping

    2005-01-01

    An increasing number of monopartite begomoviruses are being identified that a satellite molecule (DNAβ) is required to induce typical symptoms in host plants. DNAβ encodes a single gene (termed βC1) encoded in the complementary-sense. We have produced transgenic Nicotiana benthamiana and N. tabacum plants expressing theβC1 gene of a DNAβ associated with Tomato yellow leaf curl China virus (TYLCCNV), under the control of the Cauliflower mosaic virus 35S promoter. Transgenic plants expressing βC1 showed severe developmental abnormalities in both species. Microscopic analysis of sections of both transgenic and non-transgenic N. tabacum leaves showed abnormal outgrowths of transgenic N. tabacum to be due to disorganized cell division (hyperplasia) of spongy and palisade parenchyma. Immuno-gold labeling of sections with a polyclonal antibody against the βC1 protein showed that the βC1 protein accumulated in the nuclei of cells. The possible biological function of the βC1 protein was discussed.

  11. Strigolactones inhibit caulonema elongation and cell division in the moss Physcomitrella patens.

    Directory of Open Access Journals (Sweden)

    Beate Hoffmann

    Full Text Available In vascular plants, strigolactones (SLs are known for their hormonal role and for their role as signal molecules in the rhizosphere. SLs are also produced by the moss Physcomitrella patens, in which they act as signaling factors for controlling filament extension and possibly interaction with neighboring individuals. To gain a better understanding of SL action at the cellular level, we investigated the effect of exogenously added molecules (SLs or analogs in moss growth media. We used the previously characterized Ppccd8 mutant that is deficient in SL synthesis and showed that SLs affect moss protonema extension by reducing caulonema cell elongation and mainly cell division rate, both in light and dark conditions. Based on this effect, we set up bioassays to examine chemical structure requirements for SL activity in moss. The results suggest that compounds GR24, GR5, and 5-deoxystrigol are active in moss (as in pea, while other analogs that are highly active in the control of pea branching show little activity in moss. Interestingly, the karrikinolide KAR1, which shares molecular features with SLs, did not have any effect on filament growth, even though the moss genome contains several genes homologous to KAI2 (encoding the KAR1 receptor and no canonical homologue to D14 (encoding the SL receptor. Further studies should investigate whether SL signaling pathways have been conserved during land plant evolution.

  12. Strigolactones inhibit caulonema elongation and cell division in the moss Physcomitrella patens.

    Science.gov (United States)

    Hoffmann, Beate; Proust, Hélène; Belcram, Katia; Labrune, Cécile; Boyer, François-Didier; Rameau, Catherine; Bonhomme, Sandrine

    2014-01-01

    In vascular plants, strigolactones (SLs) are known for their hormonal role and for their role as signal molecules in the rhizosphere. SLs are also produced by the moss Physcomitrella patens, in which they act as signaling factors for controlling filament extension and possibly interaction with neighboring individuals. To gain a better understanding of SL action at the cellular level, we investigated the effect of exogenously added molecules (SLs or analogs) in moss growth media. We used the previously characterized Ppccd8 mutant that is deficient in SL synthesis and showed that SLs affect moss protonema extension by reducing caulonema cell elongation and mainly cell division rate, both in light and dark conditions. Based on this effect, we set up bioassays to examine chemical structure requirements for SL activity in moss. The results suggest that compounds GR24, GR5, and 5-deoxystrigol are active in moss (as in pea), while other analogs that are highly active in the control of pea branching show little activity in moss. Interestingly, the karrikinolide KAR1, which shares molecular features with SLs, did not have any effect on filament growth, even though the moss genome contains several genes homologous to KAI2 (encoding the KAR1 receptor) and no canonical homologue to D14 (encoding the SL receptor). Further studies should investigate whether SL signaling pathways have been conserved during land plant evolution.

  13. Toxoplasma exports dense granule proteins beyond the vacuole to the host cell nucleus and rewires the host genome expression.

    Science.gov (United States)

    Bougdour, Alexandre; Tardieux, Isabelle; Hakimi, Mohamed-Ali

    2014-03-01

    Toxoplasma gondii is the most widespread apicomplexan parasite and occupies a large spectrum of niches by infecting virtually any warm-blooded animals. As an obligate intracellular parasite, Toxoplasma has evolved a repertoire of strategies to fine-tune the cellular environment in an optimal way to promote growth and persistence in host tissues hence increasing the chance to be transmitted to new hosts. Short and long-term intracellular survival is associated with Toxoplasma ability to both evade the host deleterious immune defences and to stimulate a beneficial immune balance by governing host cell gene expression. It is only recently that parasite proteins responsible for driving these transcriptional changes have been identified. While proteins contained in the apical secretory Rhoptry organelle have already been identified as bona fide secreted effectors that divert host signalling pathways, recent findings revealed that dense granule proteins should be added to the growing list of effectors as they reach the host cell cytoplasm and nucleus and target various host cell pathways in the course of cell infection. Herein, we emphasize on a novel subfamily of dense granule residentproteins, exemplified with the GRA16 and GRA24 members we recently discovered as both are exported beyond the vacuole-containing parasites and reach the host cell nucleus to reshape the host genome expression.

  14. Ciprofloxacin Derivatives Affect Parasite Cell Division and Increase the Survival of Mice Infected with Toxoplasma gondii

    Science.gov (United States)

    Martins-Duarte, Erica S.; Dubar, Faustine; Lawton, Philippe; França da Silva, Cristiane; C. Soeiro, Maria de Nazaré; de Souza, Wanderley; Biot, Christophe; Vommaro, Rossiane C.

    2015-01-01

    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 show

  15. Investigating the Molecular Mechanism of TSO1 Function in Arabidopsis cell division and meristem development

    Energy Technology Data Exchange (ETDEWEB)

    Zhongchi Liu

    2004-10-01

    Unlike animals, plants are constantly exposed to environmental mutagens including ultraviolet light and reactive oxygen species. Further, plant cells are totipotent with highly plastic developmental programs. An understanding of molecular mechanisms underlying the ability of plants to monitor and repair its DNA and to eliminate damaged cells are of great importance. Previously we have identified two genes, TSO1 and TSO2, from a flowering plant Arabidopsis thaliana. Mutations in these two genes cause callus-like flowers, fasciated shoot apical meristems, and abnormal cell division, indicating that TSO1 and TSO2 may encode important cell cycle regulators. Previous funding from DOE led to the molecular cloning of TSO1, which was shown to encode a novel nuclear protein with two CXC domains suspected to bind DNA. This DOE grant has allowed us to characterize and isolate TSO2 that encodes the small subunit of the ribonucleotide reductase (RNR). RNR comprises two large subunits (R1) an d two small subunits (R2), catalyzes a rate-limiting step in the production of deoxyribonucleotides needed for DNA replication and repair. Previous studies in yeast and mammals indicated that defective RNR often led to cell cycle arrest, growth retardation and p53-dependent apoptosis while abnormally elevated RNR activities led to higher mutation rates. Subsequently, we identified two additional R2 genes, R2A and R2B in the Arabidopsis genome. Using reverse genetics, mutations in R2A and R2B were isolated, and double and triple mutants among the three R2 genes (TSO2, R2A and R2B) were constructed and analyzed. We showed that Arabidopsis tso2 mutants, with reduced dNTP levels, were more sensitive to UV-C. While r2a or r2b single mutants did not exhibit any phenotypes, tso2 r2b double mutants were embryonic lethal and tso2 r2a double mutants were seedling lethal indicating redundant functions among the three R2 genes. Furthermore, tso2 r2a double mutants exhibited increased DNA dam age

  16. 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.

  17. Exclusive multipotency and preferential asymmetric divisions in post-embryonic neural stem cells of the fish retina.

    Science.gov (United States)

    Centanin, Lázaro; Ander, Janina-J; Hoeckendorf, Burkhard; Lust, Katharina; Kellner, Tanja; Kraemer, Isabel; Urbany, Cedric; Hasel, Eva; Harris, William A; Simons, Benjamin D; Wittbrodt, Joachim

    2014-09-01

    The potency of post-embryonic stem cells can only be addressed in the living organism, by labeling single cells after embryonic development and following their descendants. Recently, transplantation experiments involving permanently labeled cells revealed multipotent neural stem cells (NSCs) of embryonic origin in the medaka retina. To analyze whether NSC potency is affected by developmental progression, as reported for the mammalian brain, we developed an inducible toolkit for clonal labeling and non-invasive fate tracking. We used this toolkit to address post-embryonic stem cells in different tissues and to functionally differentiate transient progenitor cells from permanent, bona fide stem cells in the retina. Using temporally controlled clonal induction, we showed that post-embryonic retinal NSCs are exclusively multipotent and give rise to the complete spectrum of cell types in the neural retina. Intriguingly, and in contrast to any other vertebrate stem cell system described so far, long-term analysis of clones indicates a preferential mode of asymmetric cell division. Moreover, following the behavior of clones before and after external stimuli, such as injuries, shows that NSCs in the retina maintained the preference for asymmetric cell division during regenerative responses. We present a comprehensive analysis of individual post-embryonic NSCs in their physiological environment and establish the teleost retina as an ideal model for studying adult stem cell biology at single cell resolution.

  18. Formation of cadherin-expressing brain nuclei in diencephalic alar plate divisions.

    Science.gov (United States)

    Yoon, M S; Puelles, L; Redies, C

    2000-11-01

    During the formation of brain nuclei, the vertebrate neural tube is partitioned into distinct embryonic divisions. In this study, the expression of three members of the cadherin family of adhesion molecules (cadherin-6B, cadherin-7, and R-cadherin) was mapped to study the differentiation of gray matter in the division so that diencephalic alar plate of chicken embryos from embryonic day 3 (E3) to E10. At early stages of development (E3-E4), each cadherin is expressed in restricted regions of the diencephalic wall of the neural tube. The borders of some of the expression domains coincide with divisional boundaries. As the mantle layer is formed and increases in thickness from E4 to E8, morphologically discernible aggregates of cells appear that express the three cadherins differentially. These aggregates represent the anlagen of specific diencephalic brain nuclei, e.g., the lateroanterior nucleus, the ventral geniculate nucleus, the nucleus rotundus, the perirotundic area, the principal precommissural nucleus, and the lateral spiriform nucleus. Most of the cadherin-expressing diencephalic nuclei studied in this work apparently derive from a single embryonic division and remain there. The divisional boundaries are replaced gradually by the borders of cadherin-expressing brain nuclei. The current results support the idea that cadherins confer differential adhesiveness to developing structures of gray matter in the diencephalic alar plate. Moreover, they suggest that each cadherin plays a role in the formation of specific brain nuclei within the diencephalic divisions.

  19. Chemical Topography of Efferent Projections from the Median Preoptic Nucleus to Pontine Monoaminergic Cell Groups in the Rat

    Science.gov (United States)

    Zardetto-Smith, Andrea M.; Johnson, Alan Kim

    1995-01-01

    This study examined efferent output from the median preoptic nucleus (MNPO) to pontine noradrenergic and serotonergic cell groups using an anterograde tracing technique (Phaseolus vulgaris leucoagglutinin, PHA-L) combined with glucose oxidase immunocytochemistry to serotonin (5-HT) or to dopamine-beta-hydroxylase (DBH). Injections of PHA-L into the ventral MNPO resulted in moderate axonal labeling within the region of the B7 and B8 serotonergic groups in the dorsal raphe. PHA-L labeled fibers and punctate processes were observed in close apposition to many of the 5-HT immunoreactive neurons in these regions. In contrast, sparse terminal labeling was found within the B5 group in the raphe pontis nucleus, and only trace fiber labeling observed in the B3 and B6 groups. Efferents from the MNPO also provided moderate innervation to the A6 and A7 noradrenergic groups. PHA-L labeled punctate processes were found most frequently in close apposition to DBH-immunoreactive neurons at mid- to caudal levels of the locus coeruleus. Some labeled axons were also present within the A7 and A5 groups. Additionally, a close apposition between labeled MNPO efferents and 5-HT fibers within the lateral parabrachial nucleus was observed. The results indicate the MNPO provides a topographic innervation of monoaminergic groups in the upper brainstem.

  20. Well-posedness and asynchronous exponential growth of solutions of a two-phase cell division model

    Directory of Open Access Journals (Sweden)

    Meng Bai

    2010-04-01

    Full Text Available In this article we study a two-phase cell division model. The cells of the two different phases have different growth rates. We mainly consider the model of equal mitosis. By using the semigroup theory, we prove that this model is well-posed in suitable function spaces and its solutions have the property of asynchronous exponential growth as time approaches infinity. The corresponding model of asymmetric mitosis is also studied and similar results are obtained.

  1. A role for katanin in plant cell division: microtubule organization in dividing root cells of fra2 and lue1Arabidopsis thaliana mutants.

    Science.gov (United States)

    Panteris, Emmanuel; Adamakis, Ioannis-Dimosthenis S; Voulgari, Georgia; Papadopoulou, Galini

    2011-07-01

    Severing of microtubules by katanin has proven to be crucial for cortical microtubule organization in elongating and differentiating plant cells. On the contrary, katanin is currently not considered essential during cell division in plants as it is in animals. However, defects in cell patterning have been observed in katanin mutants, implying a role for it in dividing plant cells. Therefore, microtubule organization was studied in detail by immunofluorescence in dividing root cells of fra2 and lue1 katanin mutants of Arabidopsis thaliana. In both, early preprophase bands consisted of poorly aligned microtubules, prophase spindles were multipolar, and the microtubules of expanding phragmoplasts were elongated, bended toward and connected to the surface of daughter nuclei. Accordingly, severing by katanin seems to be necessary for the proper organization of these microtubule arrays. In both fra2 and lue1, metaphase/anaphase spindles and initiating phragmoplasts exhibited typical organization. However, they were obliquely oriented more frequently than in the wild type. It is proposed that this oblique orientation may be due to prophase spindle multipolarity and results in a failure of the cell plate to follow the predetermined division plane, during cytokinesis, producing oblique cell walls in the roots of both mutants. It is therefore concluded that, like in animal cells, katanin is important for plant cell division, influencing the organization of several microtubule arrays. Moreover, failure in microtubule severing indirectly affects the orientation of the division plane.

  2. Stereological analysis of the mediodorsal thalamic nucleus in schizophrenia: volume, neuron number, and cell types

    DEFF Research Database (Denmark)

    Dorph-Petersen, Karl-Anton; Pierri, Joseph N; Sun, Zhuoxin

    2004-01-01

    The mediodorsal thalamic nucleus (MD) is the principal relay nucleus for the prefrontal cortex, a brain region thought to be dysfunctional in schizophrenia. Several, but not all, postmortem studies of the MD in schizophrenia have reported decreased volume and total neuronal number. However......, it is not clear whether the findings are specific for schizophrenia nor is it known which subtypes of thalamic neurons are affected. We studied the left MD in 11 subjects with schizophrenia, 9 control subjects, and 12 subjects with mood disorders. Based on morphological criteria, we divided the neurons into two...... subclasses, presumably corresponding to projection neurons and local circuit neurons. We estimated MD volume and the neuron number of each subclass using methods based on modern unbiased stereological principles. We also estimated the somal volumes of each subclass using a robust, but biased, approach...

  3. Structural reorganization of the bacterial cell-division protein FtsZ from Staphylococcus aureus.

    Science.gov (United States)

    Matsui, Takashi; Yamane, Junji; Mogi, Nobuyuki; Yamaguchi, Hiroto; Takemoto, Hiroshi; Yao, Min; Tanaka, Isao

    2012-09-01

    FtsZ is a key molecule in bacterial cell division. In the presence of GTP, it polymerizes into tubulin-like protofilaments by head-to-tail association. Protofilaments of FtsZ seem to adopt a straight or a curved conformation in relation to the bound nucleotide. However, although several bacterial and archaeal FtsZ structures have been determined, all of the structures reported previously are considered to have a curved conformation. In this study, structures of FtsZ from Staphylococcus aureus (SaFtsZ) were determined in apo, GDP-bound and inhibitor-complex forms and it was found that SaFtsZ undergoes marked conformational changes. The accumulated evidence suggests that the GDP-bound structure has the features of the straight form. The structural change between the curved and straight forms shows intriguing similarity to the eukaryotic cytoskeletal protein tubulin. Furthermore, the structure of the apo form showed an unexpectedly large conformational change in the core region. FtsZ has also been recognized as a novel target for antibacterial drugs. The structure of the complex with the inhibitor PC190723, which has potent and selective antistaphylococcal activity, indicated that the inhibitor binds at the cleft between the two subdomains.

  4. Single-cell spatial reconstruction reveals global division of labour in the mammalian liver.

    Science.gov (United States)

    Bahar Halpern, Keren; Shenhav, Rom; Matcovitch-Natan, Orit; Tóth, Beáta; Lemze, Doron; Golan, Matan; Massasa, Efi E; Baydatch, Shaked; Landen, Shanie; Moor, Andreas E; Brandis, Alexander; Giladi, Amir; Stokar-Avihail, Avigail; David, Eyal; Amit, Ido; Itzkovitz, Shalev

    2017-02-16

    The mammalian liver consists of hexagon-shaped lobules that are radially polarized by blood flow and morphogens. Key liver genes have been shown to be differentially expressed along the lobule axis, a phenomenon termed zonation, but a detailed genome-wide reconstruction of this spatial division of labour has not been achieved. Here we measure the entire transcriptome of thousands of mouse liver cells and infer their lobule coordinates on the basis of a panel of zonated landmark genes, characterized with single-molecule fluorescence in situ hybridization. Using this approach, we obtain the zonation profiles of all liver genes with high spatial resolution. We find that around 50% of liver genes are significantly zonated and uncover abundant non-monotonic profiles that peak at the mid-lobule layers. These include a spatial order of bile acid biosynthesis enzymes that matches their position in the enzymatic cascade. Our approach can facilitate the reconstruction of similar spatial genomic blueprints for other mammalian organs.

  5. Asymmetric cell division and Notch signaling specify dopaminergic neurons in Drosophila.

    Science.gov (United States)

    Tio, Murni; Toh, Joanne; Fang, Wanru; Blanco, Jorge; Udolph, Gerald

    2011-01-01

    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.

  6. SU-E-T-494: Influence of Proton Track-Cell Nucleus Incidence Angle On Relative Biological Effectiveness

    Energy Technology Data Exchange (ETDEWEB)

    Pater, P; Backstrom, G; Enger, S; Seuntjens, J; El Naqa, I [McGill University, Montreal, Quebec (Canada); Villegas, F; Ahnesjo, A [Uppsala University, Uppsala (Sweden)

    2015-06-15

    Purpose: To explain a Monte Carlo (MC) simulation artifact whereby differences in relative biological effectiveness (RBE) in the induction of initial double strand breaks are observed as a function of the proton track incidence angles in a geometric cell nucleus model. Secondly, to offer an alternative isotropic irradiation procedure to mitigate this effect. Methods: MC tracks of 1 MeV protons were generated in an event-by-event mode. They were overlaid on a cylindrical model of a cell nucleus containing 6×109 nucleotide base pairs. The tracks incidence angle θ with respect to the cell nucleus’s axis was varied in 10 degrees intervals, each time generating one hundred fractions of ∼2 Gy. Strand breaks were scored in the modeled DNA sugar-phosphate groups and further sub-classified into single or double strand breaks (ssbs or dsbs). For each angle, an RBE for the induction of initial dsbs with reference to Co-60 was calculated. Results: Our results show significant angular dependencies of RBE, with maximum values for incidence angles parallel to the nucleus central axis. Further examination shows that the higher cross-sections for the creation of dsbs is due to the preferential alignment of tracks with geometrical sub-parts of the cell nucleus model, especially the nucleosomes containing the sugar-phosphate groups. To alleviate the impact of this simulation artifact, an average RBE was calculated with a procedure based on a weighted sampling of the angular data. Conclusion: This work demonstrates a possible numerical artifact in estimated RBE if the influence of the particle incidence angle is not correctly taken into account. A correction procedure is presented to better conform the simulations to real-life experimental conditions. We would like to acknowledge support from the Fonds de recherche du Quebec Sante (FRQS), from the CREATE Medical Physics Research Training Network grant (number 432290) of NSERC, support from NSERC under grants RGPIN 397711-11 and

  7. The effect of extracellular pH on matrix turnover by cells of the bovine nucleus pulposus

    OpenAIRE

    Razaq, Sajjad; Wilkins, Robert J.; Urban, Jill P. G.

    2003-01-01

    It has long been known that very acidic conditions can be found in degenerate discs. The effect of these acid conditions on matrix turnover are, however, unknown. This study aimed to examine the effect of acidity on production of matrix components and on agents which break down the matrix in order to gain insight into the effect of pathological values of pH on matrix turnover. Cells were isolated from the nucleus of bovine discs and from bovine articular cartilage, embedded in alginate beads ...

  8. 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.

  9. A Vivens Ex Vivo Study on the Synergistic Effect of Electrolysis and Freezing on the Cell Nucleus.

    Science.gov (United States)

    Lugnani, Franco; Zanconati, Fabrizio; Marcuzzo, Thomas; Bottin, Cristina; Mikus, Paul; Guenther, Enric; Klein, Nina; Rubinsky, Liel; Stehling, Michael K; Rubinsky, Boris

    2015-01-01

    Freezing-cryosurgery, and electrolysis-electrochemical therapy (EChT), are two important minimally invasive surgery tissue ablation technologies. Despite major advantages they also have some disadvantages. Cryosurgery cannot induce cell death at high subzero freezing temperatures and requires multiple freeze thaw cycles, while EChT requires high concentrations of electrolytic products-which makes it a lengthy procedure. Based on the observation that freezing increases the concentration of solutes (including products of electrolysis) in the frozen region and permeabilizes the cell membrane to these products, this study examines the hypothesis that there could be a synergistic effect between freezing and electrolysis in their use together for tissue ablation. Using an animal model we refer to as vivens ex vivo, which may be of value in reducing the use of animals for experiments, combined with a Hematoxylin stain of the nucleus, we show that there are clinically relevant protocols in which the cell nucleus appears intact when electrolysis and freezing are used separately but is affected by certain combinations of electrolysis and freezing.

  10. A Vivens Ex Vivo Study on the Synergistic Effect of Electrolysis and Freezing on the Cell Nucleus

    Science.gov (United States)

    Lugnani, Franco; Zanconati, Fabrizio; Marcuzzo, Thomas; Bottin, Cristina; Mikus, Paul; Guenther, Enric; Klein, Nina; Rubinsky, Liel; Stehling, Michael K.; Rubinsky, Boris

    2015-01-01

    Freezing—cryosurgery, and electrolysis—electrochemical therapy (EChT), are two important minimally invasive surgery tissue ablation technologies. Despite major advantages they also have some disadvantages. Cryosurgery cannot induce cell death at high subzero freezing temperatures and requires multiple freeze thaw cycles, while EChT requires high concentrations of electrolytic products—which makes it a lengthy procedure. Based on the observation that freezing increases the concentration of solutes (including products of electrolysis) in the frozen region and permeabilizes the cell membrane to these products, this study examines the hypothesis that there could be a synergistic effect between freezing and electrolysis in their use together for tissue ablation. Using an animal model we refer to as vivens ex vivo, which may be of value in reducing the use of animals for experiments, combined with a Hematoxylin stain of the nucleus, we show that there are clinically relevant protocols in which the cell nucleus appears intact when electrolysis and freezing are used separately but is affected by certain combinations of electrolysis and freezing. PMID:26695185

  11. Mutations Decreasing Intrinsic β-Lactam Resistance Are Linked to Cell Division in the Nosocomial Pathogen Acinetobacter baumannii.

    Science.gov (United States)

    Knight, Daniel; Dimitrova, Daniela D; Rudin, Susan D; Bonomo, Robert A; Rather, Philip N

    2016-06-01

    Transposon mutagenesis was used to identify novel determinants of intrinsic β-lactam resistance in Acinetobacter baumannii An EZ-Tn5 transposon insertion in a gene corresponding to the A1S_0225 sequence resulted in a 4-fold decrease in resistance to ampicillin, cefotaxime, imipenem, and ceftriaxone but did not alter resistance to other classes of antibiotics. Based on this phenotype, the gene was designated blhA (β-lactam hypersusceptibility). The blhA::EZ-Tn5 mutation conferred a similar phenotype in A. baumannii strain ATCC 17978. The wild-type blhA gene complemented the blhA::EZTn5 insertion and restored β-lactam resistance levels back to wild-type levels. The blhA mutation also increased β-lactam susceptibility in an adeB adeJ double mutant, indicating that the blhA mutation acted independently of these efflux systems to mediate susceptibility. In addition, mRNA levels for the blaOXA and blaADC β-lactamase genes were not altered by the blhA mutation. The blhA mutation resulted in a prominent cell division and morphological defect, with cells exhibiting a highly elongated phenotype, combined with large bulges in some cells. The blhA gene is unique to Acinetobacter and likely represents a novel gene involved in cell division. Three additional mutations, in zipA, zapA, and ftsK, each of which encode predicted cell division proteins, also conferred increased β-lactam susceptibility, indicating a common link between cell division and intrinsic β-lactam resistance in A. baumannii.

  12. 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.

  13. Organization and transcription of the division cell wall (dcw) cluster in Neisseria gonorrhoeae.

    Science.gov (United States)

    Francis, F; Ramirez-Arcos, S; Salimnia, H; Victor, C; Dillon, J R

    2000-06-27

    A cluster of genes involved in cell division and cell wall (dcw) biosynthesis was identified in Neisseria gonorrhoeae using genomic analysis and through verification of gene order by polymerase chain reaction (PCR) analysis. The gonococcal dcw cluster consists of 17 genes, in the order 5'-mraZ-mraW-ftsI-murE-hyp1-murF- mraY-hyp2-murD-ftsW-murG-murC-ddl -ft sQ-ftsA-ftsZ-hyp3-3'. The gene organization of the dcw cluster of N. gonorrhoeae is more similar to that observed in Gram-negative rods such as Escherichia coli and Haemophilus influenzae than in Gram-positive bacteria. The cluster is characterized by several intergenic spaces. Compared with E. coli, two genes, ftsL and envA, are absent in the gonococcal dcw cluster and three hypothetical genes are novel to the cluster. The cluster is flanked by two transcriptional terminators consisting of paired neisserial uptake sequences and also includes four internal terminators, three of which are paired neisserial uptake sequences. We also found that a repeated sequence on the gonococcal genome, commonly called a Correia element, acts as the fourth transcriptional terminator. All termination sequences were shown to be fully functional by using reverse transcription PCR experiments. Transcriptional start sites upstream of ftsQ, ftsA and ftsZ were determined by primer extension and six promoters were identified; three promoters were located upstream of ftsZ in the intergenic space, two were upstream of ftsA within ftsQ and one was upstream of ftsQ within ddl. Some of these promoters were preferentially used under anaerobic conditions. The location of these promoters differed from those described in E. coli indicating dissimilar transcriptional regulation.

  14. Phylogeny of nucleus medianus of the posterior tubercle in rayfinned fishes.

    Science.gov (United States)

    Northcutt, R Glenn

    2009-03-01

    The brains of ray-finned fishes form a morphocline of increasing complexity, from cladistians through teleosts. This is particularly apparent in the posterior tubercle of the diencephalon. In cladistians, the posterior tubercle consists of a periventricular nucleus and a migrated nucleus medianus that is fused across the midline. In more advanced ray-finned fishes, such as gars and bowfins, the posterior tubercle comprises numerous additional migrated nuclei, termed the preglomerular complex, in addition to a more well developed nucleus medianus. In teleosts, the most derived ray-finned fishes, there is an even more elaborate preglomerular complex, but there is no recognizable nucleus medianus. In an attempt to explain the variation in the posterior tubercle of the diencephalon in ray-finned fishes, the immunohistochemistry and connections of nucleus medianus were examined in cladistians, gars and bowfins. In each of these taxa, nucleus medianus exhibits large numbers of calretinin-positive neurons and has ascending projections that terminate in several divisions of the pallium. Although teleosts, such as goldfish, also exhibit numerous cell groups in the posterior tubercle that are rich in calretinin, none of these cell groups has connections that are comparable to those of nucleus medianus in non-teleost ray-finned fishes. It is possible, therefore, that nucleus medianus was lost with the origin of teleosts.

  15. Carbofuran alters centrosome and spindle organization, and delays cell division in oocytes and mitotic cells.

    Science.gov (United States)

    Cinar, Ozgur; Semiz, Olcay; Can, Alp

    2015-04-01

    Although many countries banned of its usage, carbofuran (CF) is still one of the most commonly used carbamate derivative insecticides against insects and nematodes in agriculture and household, threatening the human and animal health by contaminating air, water, and food. Our goal was to evaluate the potential toxic effects of CF on mammalian oocytes besides mitotic cells. Caspase-dependent apoptotic pathway was assessed by immunofluorescence and western blot techniques. Alterations in the meiotic spindle formation after CF exposure throughout the in vitro maturation of mice oocyte-cumulus complexes (COCs) were analyzed by using a 3D confocal laser microscope. Maturation efficiency and kinetics were assessed by direct observation of the COCs. Results indicated that the number of TUNEL-positive cells increased in CF-exposed groups, particularly higher doses (>250 µM) in a dose-dependent fashion. The ratio of anticleaved caspase-3 labeled cells in those groups positively correlated with TUNEL-positivity. Western blot analysis confirmed a significant increase in active caspase-3 activity. CF caused a dose-dependent accumulation of oocytes at prometaphase-I (PM-I) of meiosis. Partial loss of spindle microtubules (MTs) was noted, which consequently gave rise to a diamond shape spindle. Aberrant pericentrin foci were noted particularly in PM-I and metaphase-I (M-I) stages. Conclusively, CF (1) induces programmed cell death in a dose-dependent manner, and (2) alters spindle morphology most likely through a mechanism that interacts with MT assembly and/or disorientation of pericentriolar proteins. Overall, data suggest that CF could give rise to aneuploidy or cell death in higher doses, therefore reduce fertilization and implantation rates.

  16. New insights into FtsZ rearrangements during the cell division of Escherichia coli from single-molecule localization microscopy of fixed cells.

    Science.gov (United States)

    Vedyaykin, Alexey D; Vishnyakov, Innokentii E; Polinovskaya, Vasilisa S; Khodorkovskii, Mikhail A; Sabantsev, Anton V

    2016-06-01

    FtsZ - a prokaryotic tubulin homolog - is one of the central components of bacterial division machinery. At the early stage of cytokinesis FtsZ forms the so-called Z-ring at mid-cell that guides septum formation. Many approaches were used to resolve the structure of the Z-ring, however, researchers are still far from consensus on this question. We utilized single-molecule localization microscopy (SMLM) in combination with immunofluorescence staining to visualize FtsZ in Esherichia coli fixed cells that were grown under slow and fast growth conditions. This approach allowed us to obtain images of FtsZ structures at different stages of cell division and accurately measure Z-ring dimensions. Analysis of these images demonstrated that Z-ring thickness increases during constriction, starting at about 70 nm at the beginning of division and increasing by approximately 25% half-way through constriction.

  17. Correlative Analysis on the Relationship between PMI and DNA Degradation of Cell Nucleus in Human Different Tissues

    Institute of Scientific and Technical Information of China (English)

    SHU Xiji; LIU Yaling; REN Liang; HE Fanggang; ZHOU Hongyan; LIU Lijiang; LIU Liang

    2005-01-01

    To determining the postmortem interval (PMI) through quantitative analysis of the DNA degradation of cell nucleus in human brain and spleen by using image analysis technique (IAT). The brain and spleen tissues from 32 cadavers with known PMI were collected, subjected to cell smear every 1 h within the first 5-36 h after death, stained by Feulgen-Van's staining, Three indices reflecting DNA in brain cells (astrocytes) and splenic lymphocytes, including integral optical density (IOD), average optical density (AOD), average gray (AG) were measured by employing the mage analysis instrument. The results showed that IOD and AOD declined and AG increased with the prolongation of dead time within 5-36 h. A correlation between the PMI and gray parameters (IOD,AOD and AG) was identified and the corresponding regression equation was obtained. The parameters (IOD,AOD and AG) were proved to be effective quantitative indicators for accurate estimation of PMI within 5-36 h after death.

  18. Self-organization and advective transport in the cell polarity formation for asymmetric cell division.

    Science.gov (United States)

    Seirin Lee, Sungrim; Shibata, Tatsuo

    2015-10-07

    Anterior-Posterior (AP) polarity formation of cell membrane proteins plays a crucial role in determining cell asymmetry, which depends not only on the several genetic process but also biochemical and biophysical interactions. The mechanism of AP formation of Caenorhabditis elegans embryo is characterized into the three processes: (i) membrane association and dissociation of posterior and anterior proteins, (ii) diffusion into the membrane and cytosol, and (iii) active cortical and cytoplasmic flows induced by the contraction of the acto-myosin cortex. We explored the mechanism of symmetry breaking and AP polarity formation using self-recruitment model of posterior proteins. We found that the AP polarity pattern is established over wide range in the total mass of polarity proteins and the diffusion ratio in the cytosol to the membrane. We also showed that the advective transport in both membrane and cytosol during the establishment phase affects optimal time interval of establishment and positioning of the posterior domain, and plays a role to increase the robustness in the AP polarity formation by reducing the number of posterior domains for the sensitivity of initial conditions. We also demonstrated that a proper ratio of the total mass to cell size robustly regulate the length scale of the posterior domain.

  19. Growth and cell-division in extensive (XDR) and extremely drug resistant (XXDR) tuberculosis strains: transmission and atomic force observation.

    Science.gov (United States)

    Farnia, Parissa; Mohammad, Reza Masjedi; Merza, Muayad Aghali; Tabarsi, Payam; Zhavnerko, Gennadii Konstantinovich; Ibrahim, Tengku Azmi; Kuan, Ho Oi; Ghanavei, Jalladein; Farnia, Poopak; Ranjbar, Reza; Poleschuyk, Nikolai Nikolaevich; Titov, Leonid Petrovich; Owlia, Parviz; Kazampour, Mehadi; Setareh, Mohammad; Sheikolslami, Muaryam; Migliori, Giovanni Battista; Velayati, Ali Akbar

    2010-09-30

    The ultra-structure of Mycobacterium tuberculosis (MTB) was examined by transmission electronic (TEM)) and atomic force microscopy (AFM). The study was performed to describe the morphology of susceptible, multidrug-resistant (MDR), extensively drug-resistant (XDR) and extremely drug-resistant tuberculosis isolates (XXDR-TB) during their exponential growth phase. Four types of cell division were observed and described. While three of them (symmetrical, asymmetrical and branching type) occurred in all isolates studied, the fourth one (adapted type) was seen only in XDR and XXDR-TB bacilli. In the fourth type of cell division, a rod shaped mother cell produced a small round shape bacillus (0.3-0.5 μm). These round cells were different from buds or polar division, but similar to terminal endospores without showing the typing heat resistance. Based on the present observation, we suggest that XDR-and XXDR-TB bacilli accommodate changes helping them to overcome the hostile environment. Viewed under AFM, the other frequently detected shapes in MTB isolates were oval, V, Y and multi-branching filaments. These shape variation confirmed pleomorphic phenomena in MTB populations and the specific features of pan-resistant strains.

  20. Kinetics of low threshold calcium channels of relay cells in cat lateral geniculate nucleus

    Institute of Scientific and Technical Information of China (English)

    罗茀荪; S.M.Sherman

    1996-01-01

    Kinetics of the low threshold T-type Ca2+ channel is studied with single electrode voltage damp technique on brain slices of the cat lateral geniculate nucleus (LGN). Space damp is dramatically improved by blocking various K+ and Na+ channels, decreasing Ca2+ current and selecting proper holding potentials. Results from this study are similar to those obtained from acutely dissociated LGN neurons of the rat, indicating that the kinetics of T-Ca2+ channels of the cat LGN neurons is the same as that of the rat LGN. The result reported previously on the cat LGN may result from a defect in space damp.

  1. Implications of intravital imaging of murine germinal centres on the control of B cell selection and division

    Directory of Open Access Journals (Sweden)

    Sebastian C. Binder

    2016-12-01

    Full Text Available Intravital imaging of antibody optimization in germinal centre (GC reactions hasset a new dimension in the understanding of the humoral immune response duringthe last decade. The inclusion of spatio-temporal cellular dynamics inthe research on GCs required analysis with agent-based mathematical models.Here, we integrate the available intravital imaging data from various researchgroups and incorporate these into a quantitative mathematical model ofGC reactions and antibody affinity maturation. Interestingly, the integrationof data concerning the spatial organisation of GCs and B cell motility allows to drawconclusions on the strength of the selection pressure and the controlof B cell division by T follicular helper cells.

  2. Actin related protein complex subunit 1b controls sperm release, barrier integrity and cell division during adult rat spermatogenesis.

    Science.gov (United States)

    Kumar, Anita; Dumasia, Kushaan; Deshpande, Sharvari; Gaonkar, Reshma; Balasinor, N H

    2016-08-01

    Actin remodeling is a vital process for signaling, movement and survival in all cells. In the testes, extensive actin reorganization occurs at spermatid-Sertoli cell junctions during sperm release (spermiation) and at inter Sertoli cell junctions during restructuring of the blood testis barrier (BTB). During spermiation, tubulobulbar complexes (TBCs), rich in branched actin networks, ensure recycling of spermatid-Sertoli cell junctional molecules. Similar recycling occurs during BTB restructuring around the same time as spermiation occurs. Actin related protein 2/3 complex is an essential actin nucleation and branching protein. One of its subunits, Arpc1b, was earlier found to be down-regulated in an estrogen-induced rat model of spermiation failure. Also, Arpc1b was found to be estrogen responsive through estrogen receptor beta in seminiferous tubule culture. Here, knockdown of Arpc1b by siRNA in adult rat testis led to defects in spermiation caused by failure in TBC formation. Knockdown also compromised BTB integrity and caused polarity defects of mature spermatids. Apart from these effects pertaining to Sertoli cells, Arpc1b reduction perturbed ability of germ cells to enter G2/M phase thus hindering cell division. In summary, Arpc1b, an estrogen responsive gene, is a regulator of spermiation, mature spermatid polarity, BTB integrity and cell division during adult spermatogenesis.

  3. Divergence and transcriptional analysis of the division cell wall (dcw) gene cluster in Neisseria spp.

    Science.gov (United States)

    Snyder, Lori A S; Shafer, William M; Saunders, Nigel J

    2003-01-01

    Three of the 18 open reading frames in the division and cell wall synthesis cluster of the pathogenic Neisseria spp. are not present in the clusters of other bacterial species. The region containing two of these, dcaB and dcaC, displays interstrain and interspecies variability uncharacteristic of such clusters. 3' of dcaB is a Correia repeat enclosed element (CREE), which is only present in some strains. It has been suggested that this CREE is a transcriptional terminator, although we demonstrate otherwise. A gearbox-like promoter within this CREE is active in Escherichia coli but not in Neisseria meningitidis. There is an active promoter 5' of dcaC, although its sequence is not conserved. The presence of similarly located promoters has not been demonstrated in other species. In Neisseria lactamica, this promoter involves another dcw-associated CREE, the first demonstration of active promoter generation at the 5' end of this common intergenic, apparently mobile, element. Upstream of this promoter is an inverted pair of neisserial uptake signal sequences, which are commonly considered to be transcriptional terminators. It has been proposed to terminate transcription in this location, although we have demonstrated transcript extending through this uptake signal sequence. dcaC contains a 108 bp tandem repeat, which is present in different copy numbers in the neisserial strains examined. This investigation reveals extensive sequence variation, disputes the presence of transcriptional terminators and identifies active internal promoters in this normally highly conserved cluster of essential genes, and addresses the transcriptional activity of two common neisserial intergenic components.

  4. Characterization of the tight junction protein ZO-2 localized at the nucleus of epithelial cells.

    Science.gov (United States)

    Jaramillo, Blanca Estela; Ponce, Arturo; Moreno, Jacqueline; Betanzos, Abigail; Huerta, Miriam; Lopez-Bayghen, Esther; Gonzalez-Mariscal, Lorenza

    2004-07-01

    ZO-2 is a MAGUK protein that in confluent epithelial sheets localizes at tight junctions (TJ) whereas in sparse cultures accumulates in clusters at the nucleus. Here, we have characterized several nuclear properties of ZO-2. We observe that ZO-2 is present in the nuclear matrix and co-immunoprecipitates with lamin B(1) and actin from the nuclei of sparse cultures. We show that ZO-2 presents several NLS at its amino region, that when deleted, diminish the nuclear import of the ZO-2 amino segment and impair the ability of the region to regulate the transcriptional activity of promoters controlled by AP-1. Several RS repeats are detected in the ZO-2 amino segment, however, their deletion does not preclude the display of a speckled nuclear pattern. ZO-2 displays two putative NES. However, only the second one appears to be functional, as when conjugated to ovalbumin (OV), it is able to translocate this protein from the nucleus to the cytoplasm in a leptomycin B-sensitive way.

  5. Extracellular matrix production by nucleus pulposus and bone marrow stem cells in response to altered oxygen and glucose microenvironments.

    Science.gov (United States)

    Naqvi, Syeda M; Buckley, Conor T

    2015-12-01

    Bone marrow (BM) stem cells may be an ideal source of cells for intervertebral disc (IVD) regeneration. However, the harsh biochemical microenvironment of the IVD may significantly influence the biological and metabolic vitality of injected stem cells and impair their repair potential. This study investigated the viability and production of key matrix proteins by nucleus pulposus (NP) and BM stem cells cultured in the typical biochemical microenvironment of the IVD consisting of altered oxygen and glucose concentrations. Culture-expanded NP cells and BM stem cells were encapsulated in 1.5% alginate and ionically crosslinked to form cylindrical hydrogel constructs. Hydrogel constructs were maintained under different glucose concentrations (1, 5 and 25 mM) and external oxygen concentrations (5 and 20%). Cell viability was measured using the Live/Dead® assay and the production of sulphated glycosaminoglycans (sGAG), and collagen was quantified biochemically and histologically. For BM stem cells, IVD-like micro-environmental conditions (5 mM glucose and 5% oxygen) increased the accumulation of sGAG and collagen. In contrast, low glucose conditions (1 mM glucose) combined with 5% external oxygen concentration promoted cell death, inhibiting proliferation and the accumulation of sGAG and collagen. NP-encapsulated alginate constructs were relatively insensitive to oxygen concentration or glucose condition in that they accumulated similar amounts of sGAG under all conditions. Under IVD-like microenvironmental conditions, NP cells were found to have a lower glucose consumption rate compared with BM cells and may in fact be more suitable to adapt and sustain the harsh microenvironmental conditions. Considering the highly specialised microenvironment of the central NP, these results indicate that IVD-like concentrations of low glucose and low oxygen are critical and influential for the survival and biological behaviour of stem cells. Such findings may promote and accelerate

  6. Spatial and Temporal Quantitative Analysis of Cell Division and Elongation Rate in Growing Wheat Leaves under Saline Conditions

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Leaf growth in grasses is determined by the cell division and elongation rates, with the duration of cell elongation being one of the processes that is the most sensitive to salinity. Our objective was to investigate the distribution profiles of cell production, cell length and the duration of cell elongation in the growing zone of the wheat leaf during the steady growth phase. Plants were grown in loamy soil with or without 120 mmol/L NaCl in a growth chamber, and harvested at day 3 after leaf 4 emerged. Results show that the elongation rate of leaf 4 was reduced by 120 mmol/L NaCl during the steady growth phase. The distribution profile of the lengths of abaxial epidermal cells of leaf 4 during the steady growth stage shows a sigmoidal pattern along the leaf axis for both treatments. Although salinity did not affect or even increased the length of the epidermal cells in some locations in the growth zone compared to the control treatment, the final length of the epidermal cells was reduced by 14% at 120 mmol/L NaCl. Thus, we concluded that the observed reduction in the leaf elongation rate derived in part from the reduced cell division rate and either the shortened cell elongation zone or shortened duration of cell elongation. This suggests that more attention should be paid to the effects of salinity on those properties of cell production and the period of cell maturation that are related to the properties of cell wall.

  7. Generation of high-producing cell lines by overexpression of cell division cycle 25 homolog A in Chinese hamster ovary cells.

    Science.gov (United States)

    Lee, Kyoung Ho; Tsutsui, Tomomi; Honda, Kohsuke; Asano, Ryutaro; Kumagai, Izumi; Ohtake, Hisao; Omasa, Takeshi

    2013-12-01

    To improve the efficiency of conventional gene amplification systems, the effect of cell cycle modification during the gene amplification process on IgG production was investigated in Chinese hamster ovary (CHO) cells. The full-length cDNA of CHO cell division cycle 25 homolog A (Cdc25A) was introduced into CHO DG44 cells and the effects of CDC25A overexpression on the cell cycle, transgene copy number and IgG productivity were examined. Both wild-type and mutated CDC25A-overexpressing CHO cells showed a rapid increase in transgene copy number compared with mock cells during the gene amplification process, in both cell pools and individual clones. High-producing clones were obtained with high frequency in CDC25A-overexpressing cell pools. The specific production rate of the isolated clone CHO SD-S23 was up to 2.9-fold higher than that of mock cells in the presence of 250 nM methotrexate (MTX). Cell cycle analysis revealed that the G2 to M phase transition rate was increased ∼1.5-fold in CDC25A-overexpressing CHO cells under MTX treatment. Our results show the improvement of conventional gene amplification systems via cell cycle engineering at an early stage of cell line development.

  8. Block copolymer micelles target Auger electron radiotherapy to the nucleus of HER2-positive breast cancer cells.

    Science.gov (United States)

    Hoang, Bryan; Reilly, Raymond M; Allen, Christine

    2012-02-13

    Intracellular trafficking of Auger electron emitting radionuclides to perinuclear and nuclear regions of cells is critical to realizing their full therapeutic potential. In the present study, block copolymer micelles (BCMs) were labeled with the Auger electron emitter indium-111 ((111)In) and loaded with the radiosensitizer methotrexate. HER2 specific antibodies (trastuzumab fab) and nuclear localization signal (NLS; CGYGPKKKRKVGG) peptides were conjugated to the surface of the BCMs to direct uptake in HER2 expressing cells and subsequent localization in the cell nucleus. Cell uptake and intracellular distribution of the multifunctional BCMs were evaluated in a panel of breast cancer cell lines with different levels of HER2 expression. Indeed cell uptake was found to be HER2 density dependent, confirming receptor-mediated internalization of the BCMs. Importantly, conjugation of NLS peptides to the surface of BCMs was found to result in a significant increase in nuclear uptake of the radionuclide (111)In. Successful nuclear targeting was shown to improve the antipoliferative effect of the Auger electrons as measured by clonogenic assays. In addition, a significant radiation enhancement effect was observed by concurrent delivery of low-dose MTX and (111)In in all breast cancer cell lines evaluated.

  9. Properties of fiber cell plasma membranes isolated from the cortex and nucleus of the porcine eye lens.

    Science.gov (United States)

    Mainali, Laxman; Raguz, Marija; O'Brien, William J; Subczynski, Witold K

    2012-04-01

    The organization and physical properties of the lipid bilayer portion of intact cortical and nuclear fiber cell plasma membranes isolated from the eye lenses of two-year-old pigs were studied using electron paramagnetic resonance (EPR) spin-labeling. Membrane fluidity, hydrophobicity, and the oxygen transport parameter (OTP) were assessed from the EPR spectra of precisely positioned spin labels. Intact cortical and nuclear membranes, which include membrane proteins, were found to contain three distinct lipid environments. These lipid environments were termed the bulk lipid domain, boundary lipid domain, and trapped lipid domain (lipids in protein aggregates). The amount of boundary and trapped lipids was greater in intact nuclear membranes than in cortical membranes. The properties of intact membranes were compared with the organization and properties of lens lipid membranes made of the total lipid extracts from the lens cortex or nucleus. In cortical lens lipid membranes, only one homogenous environment was detected, which was designated as a bulk lipid domain (phospholipid bilayer saturated with cholesterol). Lens lipid membranes prepared from the lens nucleus possessed two domains, assigned as a bulk lipid domain and a cholesterol bilayer domain (CBD). In intact nuclear membranes, it was difficult to discriminate the CBD, which was clearly detected in nuclear lens lipid membranes, because the OTP measured in the CBD is the same as in the domain formed by trapped lipids. The two domains unique to intact membranes-namely, the domain formed by boundary lipids and the domain formed by trapped lipids-were most likely formed due to the presence of membrane proteins. It is concluded that formation of rigid and practically impermeable domains is enhanced in the lens nucleus, indicating changes in membrane composition that may help to maintain low oxygen concentration in this lens region.

  10. ftsZ gene and plastid division

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Plastid is one of the most important cellular organelles, the normal division process of plastid is essential for the differentiation and development of plant cells. For a long time, morphological observations and genetic analyses to special mutants are the major research fields of plastid division, but the molecular mechanisms underlying plastid division are largely unknown. Because of the endosymbiotic origin, plastid division might have mechanisms in common with those involved in bacterial cell division. It has been proved that several prokaryotic cell division genes also participate in the plastid division. Recently, the mechanisms of prokaryotic cell division have been well documented, which provides a valuable paradigm for understanding the plastid division mechanisms. In plants, the functional analyses of ftsZ, a key gene involved both in bacteria and plastid division, have established the solid foundation for people to understand the plastid division in molecular level. In this paper we will make a review for the research history and progress of plastid division.

  11. A new loss-of-function allele 28y reveals a role of ARGONAUTE1 in limiting asymmetric division of stomatal lineage ground cell

    Institute of Scientific and Technical Information of China (English)

    Kezhen Yangy; Min Jiangy; Jie Le

    2014-01-01

    In Arabidopsis thaliana L., stomata are produced through a series of divisions including asymmetric and symmetric divisions. Asymmetric entry division of meristemoid mother cellproduces two daughter cells, the smal er meristemoid and the larger sister cell, a stomatal lineage ground cell(SLGC). Stomatal lineage ground cells can differentiate into epidermal pavement cells but have the potential to divide asymmetrical y, spacing divisions, to create satel ite meristemoids. Peptide ligands and TOO MANY MOUTHS (TMM) and ERECTA family receptors regulate the initiation of stomatal lineages, activity, and orientation of spacing divisions. Here, we reported that a natural mutant 28y displayed an increased stomatal density and index. Using map-based cloning, we identified mutation in ARGONAUTE1 (AGO1) as the cause of 28y phenotypes. Time-lapse tracing of stomatal lineage cells reveals that stomatal overproduction in 28y is caused by the excessive asymmetric spacing division of SLGCs.Further genetic results demonstrated that AGO1 acts down-stream of TMM and negatively regulates the SPCH transcripts, but in a brassinosteroid-independent manner. Upregulation of AGAMOUS-LIKE16 (AGL16) in 28y mutants suggests that AGO1 is required to restrict AGL16-mediated stomatal spacing divisions, an miRNA pathway in addition to ligand-receptor signaling modules.

  12. Asymmetry of chromosome Replichores renders the DNA translocase activity of FtsK essential for cell division and cell shape maintenance in Escherichia coli.

    Science.gov (United States)

    Lesterlin, Christian; Pages, Carine; Dubarry, Nelly; Dasgupta, Santanu; Cornet, François

    2008-12-01

    Bacterial chromosomes are organised as two replichores of opposite polarity that coincide with the replication arms from the ori to the ter region. Here, we investigated the effects of asymmetry in replichore organisation in Escherichia coli. We show that large chromosome inversions from the terminal junction of the replichores disturb the ongoing post-replicative events, resulting in inhibition of both cell division and cell elongation. This is accompanied by alterations of the segregation pattern of loci located at the inversion endpoints, particularly of the new replichore junction. None of these defects is suppressed by restoration of termination of replication opposite oriC, indicating that they are more likely due to the asymmetry of replichore polarity than to asymmetric replication. Strikingly, DNA translocation by FtsK, which processes the terminal junction of the replichores during cell division, becomes essential in inversion-carrying strains. Inactivation of the FtsK translocation activity leads to aberrant cell morphology, strongly suggesting that it controls membrane synthesis at the division septum. Our results reveal that FtsK mediates a reciprocal control between processing of the replichore polarity junction and cell division.

  13. Asymmetry of chromosome Replichores renders the DNA translocase activity of FtsK essential for cell division and cell shape maintenance in Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Christian Lesterlin

    2008-12-01

    Full Text Available Bacterial chromosomes are organised as two replichores of opposite polarity that coincide with the replication arms from the ori to the ter region. Here, we investigated the effects of asymmetry in replichore organisation in Escherichia coli. We show that large chromosome inversions from the terminal junction of the replichores disturb the ongoing post-replicative events, resulting in inhibition of both cell division and cell elongation. This is accompanied by alterations of the segregation pattern of loci located at the inversion endpoints, particularly of the new replichore junction. None of these defects is suppressed by restoration of termination of replication opposite oriC, indicating that they are more likely due to the asymmetry of replichore polarity than to asymmetric replication. Strikingly, DNA translocation by FtsK, which processes the terminal junction of the replichores during cell division, becomes essential in inversion-carrying strains. Inactivation of the FtsK translocation activity leads to aberrant cell morphology, strongly suggesting that it controls membrane synthesis at the division septum. Our results reveal that FtsK mediates a reciprocal control between processing of the replichore polarity junction and cell division.

  14. Universal Protein Distributions in a Model of Cell Growth and Division

    CERN Document Server

    Brenner, Naama; Osmanovic, Dino; Rabin, Yitzhak; Salman, Hanna; Stein, D L

    2015-01-01

    Protein distributions measured under a broad set of conditions in bacteria and yeast exhibit a universal skewed shape, with variances depending quadratically on means. For bacteria these properties are reproduced by protein accumulation and division dynamics across generations. We present a stochastic growth-and-division model with feedback which captures these observed properties. The limiting copy number distribution is calculated exactly, and a single parameter is found to determine the distribution shape and the variance-to-mean relation. Estimating this parameter from bacterial temporal data reproduces the measured universal distribution shape with high accuracy, and leads to predictions for future experiments.

  15. Dihydroartemisinin (DHA) treatment causes an arrest of cell division and apoptosis in rat embryonic erythroblasts in whole embryo culture.

    Science.gov (United States)

    Posobiec, Lorraine M; Clark, Robert L; Bushdid, Paul B; Laffan, Susan B; Wang, Kai-Fen; White, Tacey E K

    2013-12-01

    Within 24 hr after oral administration of the antimalarial artesunate to rats on Day 10 or 11 postcoitum (pc), there is depletion of embryonic erythroblasts (EEbs), leading to embryo malformation and death. The proximate agent is dihydroartemisinin (DHA), the primary metabolite. We investigated the causes of EEb depletion by evaluating effects of DHA on EEbs in whole embryo culture (WEC). Rat embryos cultured starting on Day 9 pc were treated with 1 or 7 μM DHA for 24 hr starting after 19 hr of culture (∼Day 10 pc) and for 2 to 12 hr starting after 43 hr of culture (∼Day 11 pc). DHA effects indicating the depletion of EEbs were paling of the visceral yolk sac and reductions in visible blood cells, H&E-stained normal (Type II or III) EEbs, and dividing (BrdU-stained) EEbs. DHA-induced abnormal cell division was indicated by increases in symmetric and asymmetric binuclear cells. DHA-induced apoptosis was indicated by increases in TUNEL- and Caspase-3-positive cells and EEbs with fragmented nuclei. In addition, although the overall number of EEbs was decreasing, DHA caused increases in the numbers of circulating early-stage (Type I or earlier) EEbs that could not be accounted for by cell division, suggesting the release of new, less sensitive erythroblasts from the yolk sac. In summary, treatment of Day 10 or 11 pc rat embryos with DHA in WEC resulted in defective and arrested cell division in EEbs followed by apoptosis, suggesting a mechanism for their depletion after artesunate treatment in vivo.

  16. 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.

  17. A novel group of pumilio mutations affects the asymmetric division of germline stem cells in the Drosophila ovary.

    Science.gov (United States)

    Lin, H; Spradling, A C

    1997-06-01

    Germline stem cells play a pivotal role in gametogenesis; yet little is known about how they are formed, how they divide to self-renew, and how these processes are genetically controlled. Here we describe the self-renewing asymmetric division of germline stem cells in the Drosophila ovarian germline, as marked by the spectrosome, a cytoplasmic structure rich in membrane skeletal proteins. The ontogeny of the spectrosome marks the lineage of germline stem cells. We identified two new groups of mutations in which the divisional asymmetry is disrupted. The first, which we refer to as ovarette (ovt) mutations, was shown to correspond to a novel class of mutations in the pumilio locus. Since pumilio is known to posttranscriptionally repress the expression of target genes at earlier stages of germ cell development, our results suggest that a similar activity is needed to maintain germ line stem cells. We have also identified a second and novel gene, piwi, whose mutations abolish germline stem cell division.

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

    Directory of Open Access Journals (Sweden)

    Anthony J. Robertson

    2013-03-01

    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.

  19. One pot synthesis of highly luminescent polyethylene glycol anchored carbon dots functionalized with a nuclear localization signal peptide for cell nucleus imaging.

    Science.gov (United States)

    Yang, Lei; Jiang, Weihua; Qiu, Lipeng; Jiang, Xuewei; Zuo, Daiying; Wang, Dongkai; Yang, Li

    2015-04-14

    Strong blue fluorescent polyethylene glycol (PEG) anchored carbon nitride dots (CDs@PEG) with a high quantum yield (QY) of 75.8% have been synthesized by a one step hydrothermal treatment. CDs with a diameter of ca. 6 nm are well dispersed in water and present a graphite-like structure. Photoluminescence (PL) studies reveal that CDs display excitation-dependent behavior and are stable under various test conditions. Based on the as-prepared CDs, we designed novel cell nucleus targeting imaging carbon dots functionalized with a nuclear localization signal (NLS) peptide. The favourable biocompatibilities of CDs and NLS modified CDs (NLS-CDs) are confirmed by in vitro cytotoxicity assays. Importantly, intracellular localization experiments in MCF7 and A549 cells demonstrate that NLS-CDs could be internalized in the nucleus and show blue light, which indicates that CDs may serve as cell nucleus imaging probes.

  20. 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.

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

    Science.gov (United States)

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

    2013-11-01

    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.

  2. Intervertebral disc repair with activated nucleus pulposus cell transplantation: a three-year, prospective clinical study of its safety

    Directory of Open Access Journals (Sweden)

    J Mochida

    2015-03-01

    Full Text Available Degeneration of the lumbar intervertebral discs is irreversible, with no treatment currently available. Building upon experimental studies that demonstrated the importance of the nucleus pulposus (NP in preserving disc structure, we demonstrated that reinsertion of NP cells slowed further disc degeneration and that direct cell-to-cell contact co-culture with mesenchymal stromal cells (MSCs significantly upregulated the viability of NP cells in basic and pre-clinical studies in vitro and in vivo using animal models and human cells. Here, we report a 3-year result of a prospective clinical study, aimed to assess the safety and efficacy of activated NP cell transplantation in the degenerate lumbar intervertebral disc. Candidates were 9 patients aged 20-29 years who had Pfirrmann’s grade III disc degeneration at the level adjacent to the level scheduled for posterior lumbar intervertebral fusion. Viable NP cells from the fused disc were co-cultured in direct contact with autologous bone marrow-derived MSCs. One million activated NP cells were transplanted into the degenerated disc adjacent to the fused level at 7 d after the first fusion surgery. No adverse effects were observed during the 3-year follow-up period. Magnetic resonance imaging did not show any detrimental effects to the transplanted discs and revealed a mild improvement in 1 case. No cases reported any low back pain. Our clinical study confirmed the safety of activated NP cell transplantation, and the findings suggest the minimal efficacy of this treatment to slow the further degeneration of human intervertebral discs.

  3. Genetic Activation of Hedgehog Signaling Unbalances the Rate of Neural Stem Cell Renewal by Increasing Symmetric Divisions

    Directory of Open Access Journals (Sweden)

    Julien Ferent

    2014-08-01

    Full Text Available In the adult brain, self-renewal is essential for the persistence of neural stem cells (NSCs throughout life, but its regulation is still poorly understood. One NSC can give birth to two NSCs or one NSC and one transient progenitor. A correct balance is necessary for the maintenance of germinal areas, and understanding the molecular mechanisms underlying NSC division mode is clearly important. Here, we report a function of the Sonic Hedgehog (SHH receptor Patched in the direct control of long-term NSC self-renewal in the subependymal zone. We show that genetic conditional activation of SHH signaling in adult NSCs leads to their expansion and the depletion of their direct progeny. These phenotypes are associated in vitro with an increase in NSC symmetric division in a process involving NOTCH signaling. Together, our results demonstrate a tight control of adult neurogenesis and NSC renewal driven by Patched.

  4. Intrinsic disorder of the bacterial cell division protein ZipA: coil-to-brush conformational transition.

    Science.gov (United States)

    López-Montero, Iván; López-Navajas, Pilar; Mingorance, Jesús; Rivas, Germán; Vélez, Marisela; Vicente, Miguel; Monroy, Francisco

    2013-08-01

    The full-length ZipA protein from Escherichia coli, one of the essential elements of the cell division machinery, was studied in a surface model built as adsorbed monolayers. The interplay between lateral packing and molecular conformation was probed using a combined methodology based on the scaling analysis of the surface pressure isotherms and ellipsometry measurements of the monolayer thickness. The observed behavior is compatible with the one expected for an intrinsically disordered and highly flexible protein that is preferentially structured in a random coil conformation. At low grafting densities, ZipA coils organize in a mushroom-like regime, whereas a coil-to-brush transition occurs on increasing lateral packing. The structural results suggest a functional scenario in which ZipA acts as a flexible tether anchoring bacterial proto-ring elements to the membrane during the earlier stages of division.

  5. The fenestrin antigen in submembrane skeleton of the ciliate Tetrahymena thermophila is proposed as a marker of cell polarity during cell division and in oral replacement.

    Science.gov (United States)

    Kaczanowska, Janina; Joachimiak, Ewa; Kiersnowska, Mauryla; Krzywicka, Anna; Golinska, Krystyna; Kaczanowski, Andrzej

    2003-07-01

    Tetrahymena thermophila cells have two types of polarized morphogenesis: divisional morphogenesis and oral reorganization (OR). The aim of this research is the analysis of cortical patterns of immunostaining during cell division and in OR using previously characterized antibodies against fenestrin and epiplasm B proteins. During cell division, the anarchic field of basal body proliferation of the new developing oral apparatus (AF) showed concomitant strong binding of the fenestrin antigen and withdrawal of a signal of the epiplasm B antigen. At a specific stage, the fenestrin antigen also appeared as a character of the anterior cortex pole, with a co-localized decrease in the detected epiplasm B antigen. The fenestrin antigen also showed a polarity of duplicating basal bodies in ciliary rows. Indirect immunofluorescence and immunogold labeling experiments were performed in the absence and presence of an inhibitor of activity of serine/threonine kinases, 6-dimethylaminopurine (6-DMAP) as an inducer of the oral replacement process. In the presence of 6-DMAP, one class of cells started OR, and some others were trapped and affected in cell division. Both types of cells showed an instability of oral structures and formed enlarged primordial oral fields. These anarchic fields (AFs) bind the fenestrin antigen, with disappearance of epiplasmic antigen staining. Only one protein (about 64 kDa) is detected in western blots by the anti-fenestrin antibody and it accumulated in 6-DMAP-treated cells that are involved in uncompleted morphogenetic activity. At a defined stage of oral development, both during cell division and in OR, the fenestrin antigen served as a marker of polarity of the cell of the anterior pole character.

  6. Cell directional migration and oriented division on three-dimensional laser-induced periodic surface structures on polystyrene.

    Science.gov (United States)

    Wang, Xuefeng; Ohlin, Christian A; Lu, Qinghua; Hu, Jun

    2008-05-01

    The extracellular matrix in animal tissues usually provides a three-dimensional structural support to cells in addition to performing various other important functions. In the present study, wavy submicrometer laser-irradiated periodic surface structures (LIPSS) were produced on a smooth polystyrene film by polarized laser irradiation with a wavelength of 266 nm. Rat C6 glioma cells exhibited directional migration and oriented division on laser-irradiated polystyrene, which was parallel to the direction of LIPSS. However, rat C6 glioma cells on smooth polystyrene moved in a three-step invasion cycle, with faster migration speed than that on laser-irradiated polystyrene. In addition, focal adhesions examined by immunostaining focal adhesion kinase in human epithelial carcinoma HeLa cells were punctuated on smooth polystyrene, whereas dash-like on laser-irradiated polystyrene. We hypothesized that LIPSS on laser-irradiated polystyrene acted as an anisotropic and persistent mechanical stimulus to guide cell anisotropic spreading, migration and division through focal adhesions.

  7. Transient calcium-dependent potassium current in magnocellular neurosecretory cells of the rat supraoptic nucleus.

    Science.gov (United States)

    Bourque, C W

    1988-03-01

    1. Magnocellular neurosecretory neurones were impaled in the supraoptic nucleus of perfused explants of rat hypothalamus. Membrane currents were studied at 35 degrees C using the single-microelectrode voltage-clamp technique. 2. Depolarizing voltage steps applied from -100 mV evoked a transient outward current (TOC) from a threshold of -75 mV. From this potential, the amplitude of the current increased non-linearly with voltage. 3. Following its activation TOC reached a peak within 7 ms and subsequently decayed monotonically with a time constant of 30 ms. This time constant did not vary significantly with voltage between -75 and -55 mV. 4. The TOC showed complete steady-state inactivation at potentials positive to -55 mV. Inactivation was removed by hyperpolarization, with a mid-point near -80 mV. The removal of inactivation followed a complex time course with distinct fast (tens of milliseconds) and slow (hundreds of milliseconds) components. 5. Tail current measurements revealed that the TOC equilibrium potential (ETOC) lies near -97 mV in the presence of 3 mM [K+]o. Increasing [K+]o caused a decrease of TOC amplitude and a shift in ETOC of 57 mV/log [K+]o. The TOC is therefore predominantly a K+ current. 6. The TOC was unaffected by tetraethylammonium (up to 12 mM) but was reversibly reduced by 4-aminopyridine (ca. 50% block at 1.0 mM) and dendrotoxin (ca. 50% block at 4 nM). 7. The TOC was strongly inhibited (greater than 70%) by adding Co2+ or Mn2+ (1-3 mM) or Cd2+ (50-400 microM) to Ca-containing solutions, or by removal of Ca2+ from the perfusate. These effects were not accompanied by detectable changes in threshold voltage. The amplitude of TOC was also depressed by the organic Ca2+ channel blocker methoxyverapamil (D600). Finally replacement of Ca2+ by Ba2+ in the perfusate completely and reversibly abolished the TOC. 8. These findings suggest that neurosecretory neurones of the rat supraoptic nucleus display a transient K+ current which is strongly

  8. RNA helicase Belle (DDX3) is essential for male germline stem cell maintenance and division in Drosophila.

    Science.gov (United States)

    Kotov, Alexei A; Olenkina, Oxana M; Kibanov, Mikhail V; Olenina, Ludmila V

    2016-06-01

    The present study showed that RNA helicase Belle (DDX3) was required intrinsically for mitotic progression and survival of germline stem cells (GSCs) and spermatogonial cells in the Drosophila melanogaster testes. We found that deficiency of Belle in the male germline resulted in a strong germ cell loss phenotype. Early germ cells are lost through cell death, whereas somatic hub and cyst cell populations are maintained. The observed phenotype is related to that of the human Sertoli Cell-Only Syndrome caused by the loss of DBY (DDX3) expression in the human testes and results in a complete lack of germ cells with preservation of somatic Sertoli cells. We found the hallmarks of mitotic G2 delay in early germ cells of the larval testes of bel mutants. Both mitotic cyclins, A and B, are markedly reduced in the gonads of bel mutants. Transcription levels of cycB and cycA decrease significantly in the testes of hypomorph bel mutants. Overexpression of Cyclin B in the germline partially rescues germ cell survival, mitotic progression and fertility in the bel-RNAi knockdown testes. Taken together, these results suggest that a role of Belle in GSC maintenance and regulation of early germ cell divisions is associated with the expression control of mitotic cyclins.

  9. Asymmetry of Chromosome Replichores Renders the DNA Translocase Activity of FtsK Essential for Cell Division and Cell Shape Maintenance in Escherichia coli

    OpenAIRE

    Christian Lesterlin; Carine Pages; Nelly Dubarry; Santanu Dasgupta; François Cornet

    2008-01-01

    Bacterial chromosomes are organised as two replichores of opposite polarity that coincide with the replication arms from the ori to the ter region. Here, we investigated the effects of asymmetry in replichore organisation in Escherichia coli. We show that large chromosome inversions from the terminal junction of the replichores disturb the ongoing post-replicative events, resulting in inhibition of both cell division and cell elongation. This is accompanied by alterations of the segregation p...

  10. Aminopropyltransferases involved in polyamine biosynthesis localize preferentially in the nucleus of plant cells.

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    Borja Belda-Palazón

    Full Text Available Plant aminopropyltransferases consist of a group of enzymes that transfer aminopropyl groups derived from decarboxylated S-adenosyl-methionine (dcAdoMet or dcSAM to propylamine acceptors to produce polyamines, ubiquitous metabolites with positive charge at physiological pH. Spermidine synthase (SPDS uses putrescine as amino acceptor to form spermidine, whereas spermine synthase (SPMS and thermospermine synthase (TSPMS use spermidine as acceptor to synthesize the isomers spermine and thermospermine respectively. In previous work it was shown that both SPDS1 and SPDS2 can physically interact with SPMS although no data concerning the subcellular localization was reported. Here we study the subcellular localization of these enzymes and their protein dimer complexes with gateway-based Bimolecular Fluorescence Complementation (BiFC binary vectors. In addition, we have characterized the molecular weight of the enzyme complexes by gel filtration chromatography with in vitro assembled recombinant enzymes and with endogenous plant protein extracts. Our data suggest that aminopropyltransferases display a dual subcellular localization both in the cytosol and nuclear enriched fractions, and they assemble preferably as dimers. The BiFC transient expression data suggest that aminopropyltransferase heterodimer complexes take place preferentially inside the nucleus.

  11. Cell division in Apicomplexan parasites is organized by a homolog of the striated rootlet fiber of algal flagella.

    Science.gov (United States)

    Francia, Maria E; Jordan, Carly N; Patel, Jay D; Sheiner, Lilach; Demerly, Jessica L; Fellows, Justin D; de Leon, Jessica Cruz; Morrissette, Naomi S; Dubremetz, Jean-François; Striepen, Boris

    2012-01-01

    Apicomplexa are intracellular parasites that cause important human diseases including malaria and toxoplasmosis. During host cell infection new parasites are formed through a budding process that parcels out nuclei and organelles into multiple daughters. Budding is remarkably flexible in output and can produce two to thousands of progeny cells. How genomes and daughters are counted and coordinated is unknown. Apicomplexa evolved from single celled flagellated algae, but with the exception of the gametes, lack flagella. Here we demonstrate that a structure that in the algal ancestor served as the rootlet of the flagellar basal bodies is required for parasite cell division. Parasite striated fiber assemblins (SFA) polymerize into a dynamic fiber that emerges from the centrosomes immediately after their duplication. The fiber grows in a polarized fashion and daughter cells form at its distal tip. As the daughter cell is further elaborated it remains physically tethered at its apical end, the conoid and polar ring. Genetic experiments in Toxoplasma gondii demonstrate two essential components of the fiber, TgSFA2 and 3. In the absence of either of these proteins cytokinesis is blocked at its earliest point, the initiation of the daughter microtubule organizing center (MTOC). Mitosis remains unimpeded and mutant cells accumulate numerous nuclei but fail to form daughter cells. The SFA fiber provides a robust spatial and temporal organizer of parasite cell division, a process that appears hard-wired to the centrosome by multiple tethers. Our findings have broader evolutionary implications. We propose that Apicomplexa abandoned flagella for most stages yet retained the organizing principle of the flagellar MTOC. Instead of ensuring appropriate numbers of flagella, the system now positions the apical invasion complexes. This suggests that elements of the invasion apparatus may be derived from flagella or flagellum associated structures.

  12. Heat shock proteins IbpA and IbpB are required for NlpI-participated cell division in Escherichia coli.

    Science.gov (United States)

    Tao, Jing; Sang, Yu; Teng, Qihui; Ni, Jinjing; Yang, Yi; Tsui, Stephen Kwok-Wing; Yao, Yu-Feng

    2015-01-01

    Lipoprotein NlpI of Escherichia coli is involved in the cell division, virulence, and bacterial interaction with eukaryotic host cells. To elucidate the functional mechanism of NlpI, we examined how NlpI affects cell division and found that induction of NlpI inhibits nucleoid division and halts cell growth. Consistent with these results, the cell division protein FtsZ failed to localize at the septum but diffused in the cytosol. Elevation of NlpI expression enhanced the transcription and the outer membrane localization of the heat shock protein IbpA and IbpB. Deletion of either ibpA or ibpB abolished the effects of NlpI induction, which could be restored by complementation. The C-terminus of NlpI is critical for the enhancement in IbpA and IbpB production, and the N-terminus of NlpI is required for the outer membrane localization of NlpI, IbpA, and IbpB. Furthermore, NlpI physically interacts with IbpB. These results indicate that over-expression of NlpI can interrupt the nucleoids division and the assembly of FtsZ at the septum, mediated by IbpA/IbpB, suggesting a role of the NlpI/IbpA/IbpB complex in the cell division.

  13. Heat shock proteins IbpA and IbpB are required for NlpI-participated cell division in Escherichia coli

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    Jing eTao

    2015-02-01

    Full Text Available Lipoprotein NlpI of Escherichia coli is involved in the cell division, virulence and bacterial interaction with eukaryotic host cells. To elucidate the functional mechanism of NlpI, we examined how NlpI affects cell division and found that induction of NlpI inhibits nucleoid division and halts cell growth. Consistent with these results, the cell division protein FtsZ failed to localize at the septum but diffused in the cytosol. Elevation of NlpI expression enhanced the transcription and the outer membrane localization of the heat shock protein IbpA and IbpB. Deletion of either ibpA or ibpB abolished the effects of NlpI induction, which could be restored by complementation. The C-terminus of NlpI is critical for the enhancement in IbpA and IbpB production, and the N-terminus of NlpI is required for the outer membrane localization of NlpI, IbpA, and IbpB. Furthermore, NlpI physically interacts with IbpB. These results indicate that over-expression of NlpI can interrupt the nucleoids division and the assembly of FtsZ at the septum, mediated by IbpA/IbpB, suggesting a role of the NlpI/IbpA/IbpB complex in the cell division.

  14. Characterization of the ftsZ cell division gene of Neisseria gonorrhoeae: expression in Escherichia coli and N. gonorrhoeae.

    Science.gov (United States)

    Salimnia, H; Radia, A; Bernatchez, S; Beveridge, T J; Dillon, J R

    2000-01-01

    We cloned the cell division gene ftsZ of the gram-negative coccus Neisseria gonorrhoeae (Ng) strain CH811, characterized it genetically and phenotypically, and studied its localization in N. gonorrhoeae and Escherichia coli (Ec). The 1,179-bp ORF of ftsZ(Ng) encodes a protein with a predicted molecular mass of 41.5 kDa. Protein sequence alignments indicate that FtsZ(Ng) is similar to other FtsZ proteins and contains the conserved GTP binding motif. FtsZ homologues were identified in several N. gonorrhoeae strains and in Neisseria lactamica, Neisseria sicca, Neisseria polysaccharae and Neisseria cinerea either by Western blot or by PCR-Southern blot analysis. Attempts to inactivate the ftsZ(Ng) on the chromosome failed, indicating that it is essential for gonococcal growth. FtsZ(Ng) was synthesized in an in vitro transcription/translation system and was shown to be 43 kDa, the same size as in Western blots. Expression of the ftsZ(Ng) gene from nongonococcal promoters resulted in a filamentous phenotype in E. coli. Under controlled expression, the FtsZ(Ng)-GFP fusion protein localized at the mid-cell division site in E. coli. E. coli expressing high levels of the FtsZ(Ng)-GFP fusion protein formed filaments and exhibited different fluorescent structures including helices, spiral tubules extending from pole to pole, and regularly spaced dots or bands that did not localize at the middle of the cell. Expression of the FtsZ(Ng)-GFP fusion protein in N. gonorrhoeae resulted in abnormal cell division as shown by electron microscopy. FtsZ(Ng)-GFP fusions were also expressed in a gonococcal background using a unique shuttle vector.

  15. An examination of nucleus accumbens cell firing during extinction and reinstatement of water reinforcement behavior in rats.

    Science.gov (United States)

    Hollander, Jonathan A; Ijames, Stephanie G; Roop, Richard G; Carelli, Regina M

    2002-03-08

    Electrophysiological recording procedures were used to examine nucleus accumbens (Acb) cell firing in rats (n = 13) during water reinforcement sessions consisting of three phases. During phase one (maintenance), a lever press resulted in water reinforcement (fixed ratio 1; 0.05 ml/press) paired with an auditory stimulus (0.5 s). Of 128 Acb neurons recorded during maintenance, 40 cells (31%) exhibited one of three types of neuronal firing patterns described previously [J. Neurosci. 14 (12) (1994) 7735-7746; J. Neurosci. 20 (11) (2000) 4255-4266]. Briefly, Acb neurons exhibited increases in firing rate within seconds preceding the reinforced response (type PR) or increases (type RFe) or decreases (type RFi) in activity seconds following response completion. In phase two (extinction), subsequent lever pressing had no programmed consequences (i.e., water reinforcement and the auditory stimulus were not presented). After 30 min of no responding, animals were given water reinforcement/auditory stimulus 'primes' to reestablish lever pressing behavior during the third phase (reinstatement). Results indicated that all types of phasic neurons (PR, RFe and RFi) exhibited an attenuated firing rate during extinction, and in some cases recovery of patterned discharges were observed during reinstatement. No significant changes in cell firing were observed for any cell type during presentation of the stimulus prime used to reestablish operant responding following extinction. These findings are discussed in terms of how Acb neurons process information related to 'natural' reinforcers versus drugs of abuse.

  16. Variations in gene and protein expression in canine chondrodystrophic nucleus pulposus cells following long-term three-dimensional culture.

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    Munetaka Iwata

    Full Text Available Intervertebral disc (IVD degeneration greatly affects quality of life. The nucleus pulposus (NP of chondrodystrophic dog breeds (CDBs is similar to the human NP, because the cells disappear with age and are replaced by fibrochondrocyte-like cells. However, because IVD develops as early as within the first year of life, we used canines as a model to investigate in vitro the mechanisms underlying IVD degeneration. Specifically, we evaluated the potential of a three-dimensional (3D culture of healthy NP as an in vitro model system to investigate the mechanisms of IVD degeneration. Agarose hydrogels were populated with healthy NP cells from beagles after performing magnetic resonance imaging, and mRNA expression profiles and pericellular extracellular matrix (ECM protein distribution were determined. After 25 days of 3D culture, there was a tendency for redifferentiation into the native NP phenotype, and mRNA levels of Col2A1, COMP, and CK18 were not significantly different from those of freshly isolated cells. Our findings suggest that long-term 3D culture promoted chondrodystrophic NP redifferentiation through reconstruction of the pericellular microenvironment. Further, lipopolysaccharide (LPS induced expression of TNF-α, MMP3, MMP13, VEGF, and PGES mRNA in the 3D cultures, creating a molecular milieu that mimics that of degenerated NP. These results suggest that this in vitro model represents a reliable and cost-effective tool for evaluating new therapies for disc degeneration.

  17. 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.

  18. Systemic Control of Cell Division and Endoreduplication by NAA and BAP by Modulating CDKs in Root Tip Cells of Allium cepa

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    Jigna G. Tank

    2014-01-01

    Full Text Available 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.

  19. A P-Loop NTPase Regulates Quiescent Center Cell Division and Distal Stem Cell Identity through the Regulation of ROS Homeostasis in Arabidopsis Root

    Science.gov (United States)

    Yu, Qianqian; Tian, Huiyu; Liu, Jiajia; Zhang, Bing; Li, Xugang; Ding, Zhaojun

    2016-01-01

    Reactive oxygen species (ROS) are recognized as important regulators of cell division and differentiation. The Arabidopsis thaliana P-loop NTPase encoded by APP1 affects root stem cell niche identity through its control of local ROS homeostasis. The disruption of APP1 is accompanied by a reduction in ROS level, a rise in the rate of cell division in the quiescent center (QC) and the promotion of root distal stem cell (DSC) differentiation. Both the higher level of ROS induced in the app1 mutant by exposure to methyl viologen (MV), and treatment with hydrogen peroxide (H2O2) rescued the mutant phenotype, implying that both the increased rate of cell division in the QC and the enhancement in root DSC differentiation can be attributed to a low level of ROS. APP1 is expressed in the root apical meristem cell mitochondria, and its product is associated with ATP hydrolase activity. The key transcription factors, which are defining root distal stem niche, such as SCARECROW (SCR) and SHORT ROOT (SHR) are both significantly down-regulated at both the transcriptional and protein level in the app1 mutant, indicating that SHR and SCR are important downstream targets of APP1-regulated ROS signaling to control the identity of root QC and DSCs. PMID:27583367

  20. The ClpP protease homologue is required for the transmission traits and cell division of the pathogen Legionella pneumophila

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    Zhang Qin-fen

    2010-02-01

    Full Text Available Abstract Background Legionella pneumophila, the intracellular bacterial pathogen that causes Legionnaires' disease, exhibit characteristic transmission traits such as elevated stress tolerance, shortened length and virulence during the transition from the replication phase to the transmission phase. ClpP, the catalytic core of the Clp proteolytic complex, is widely involved in many cellular processes via the regulation of intracellular protein quality. Results In this study, we showed that ClpP was required for optimal growth of L. pneumophila at high temperatures and under several other stress conditions. We also observed that cells devoid of clpP exhibited cell elongation, incomplete cell division and compromised colony formation. Furthermore, we found that the clpP-deleted mutant was more resistant to sodium stress and failed to proliferate in the amoebae host Acanthamoeba castellanii. Conclusions The data present in this study illustrate that the ClpP protease homologue plays an important role in the expression of transmission traits and cell division of L. pneumophila, and further suggest a putative role of ClpP in virulence regulation.

  1. A conserved DNA damage response pathway responsible for coupling the cell division cycle to the circadian and metabolic cycles.

    Science.gov (United States)

    Chen, Zheng; McKnight, Steven L

    2007-12-01

    The circadian clock drives endogenous oscillations of cellular and physiological processes with a periodicity of approximately 24 h. Progression of the cell division cycle (CDC) has been found to be coupled to the circadian clock, and it has been postulated that gating of the CDC by the circadian cycle may have evolved to protect DNA from the mutagenic effects of ultraviolet light. When grown under nutrient-limiting conditions in a chemostat, prototrophic strains of budding yeast, Saccharomyces cerevisiae, adopt a robust metabolic cycle of ultradian dimensions that temporally compartmentalizes essential cellular events. The CDC is gated by this yeast metabolic cycle (YMC), with DNA replication strictly segregated away from the oxidative phase when cells are actively respiring. Mutants impaired in such gating allow DNA replication to take place during the respiratory phase of the YMC and have been found to suffer significantly elevated rates of spontaneous mutation. Analogous to the circadian cycle, the YMC also employs the conserved DNA checkpoint kinase Rad53/Chk2 to facilitate coupling with the CDC. These studies highlight an evolutionarily conserved mechanism that seems to confine cell division to particular temporal windows to prevent DNA damage. We hypothesize that DNA damage itself might constitute a "zeitgeber", or time giver, for both the circadian cycle and the metabolic cycle. We discuss these findings in the context of a unifying theme underlying the circadian and metabolic cycles, and explore the relevance of cell cycle gating to human diseases including cancer.

  2. Trisomy 18: studies of the parent and cell division of origin and the effect of aberrant recombination on nondisjunction

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, J.M.; Harvey, J.F.; Jacobs, P.A. [Salisbury District Hospital (United Kingdom); Morton, N.E. [CRC Epidemiology Research Group, Southampton (United Kingdom)

    1995-03-01

    We have studied the mechanism of origin of 63 cases of trisomy 18. In 2 the additional chromosome was paternal in origin, and in the remaining 61 it was maternal in origin. Both paternal cases were attributable to a postzygotic mitotic (PZM) error. Among the 54 maternal cases for which the cell division of error was established, only 16 were attributable to an error at the first meiotic division (mat MI), whereas no fewer than 35 were due an error at the second meiotic division (mat MII), the remaining 3 being the result of a PZM error involving the maternal chromosome 18. A standard map of chromosome 18 was constructed and compared with the nondisjunctional map. Approximately one-third of the mat MI errors were associated with complete absence of recombination, whereas in the remaining two-thirds and in all the mat MII errors recombination in the nondisjoined chromosomes appeared to be normal. All the maternal errors were associated with an increased maternal age, although this reached significance only for the mat MII category of nondisjunction. Our observations on chromosome 18 are compared with those on other chromosomes for which there are comparable data. 37 refs., 7 tabs.

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

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    Yu Zhang

    2017-02-01

    Full Text Available 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.

  4. Characterization of inner membrane protein YciB in Escherichia coli: YciB interacts with cell elongation and division proteins.

    Science.gov (United States)

    Li, Gaochi; Badaluddin, Noor Afiza; Kitakawa, Madoka

    2015-11-01

    The function of inner membrane protein YciB in Escherichia coli has not been identified. In this study, the membrane topology of the protein that contains five transmembrane domains was clarified. YciB was found to interact with various proteins involved in cell elongation and cell division using a bacterial two-hybrid system. It was also found that the deletion mutant of yciB is susceptible to the low osmolarity. These observations together with previous reports indicate that YciB is involved in synthesis of the cell envelope by interacting with cell elongation and cell division complexes.

  5. The nucleus of differentiated root plant cells: modifications induced by arbuscular mycorrhizal fungi

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    G Lingua

    2009-12-01

    Full Text Available The nuclei of plant cells show marked differences in chromatin organisation, related to their DNA content, which ranges from the type with large strands of condensed chromatin (reticulate or chromonematic nuclei to one with mostly decondensed chromatin (chromocentric or diffuse nuclei. A loosening of the chromatin structure generally occurs in actively metabolising cells, such as differentiating and secretory cells, in relation to their high transcriptional activity. Endoreduplication may occur, especially in plants with a small genome, which increases the availability of nuclear templates, the synthesis of DNA, and probably regulates gene expression. Here we describe structural and quantitative changes of the chromatin and their relationship with transcription that occur in differentiated cells following an increase of their metabolism. The nuclei of root cortical cells of three plants with different 2C DNA content (Allium porrum, Pisum sativum and Lycopersicon esculentm and their modifications induced by arbuscular mycorrhization, which strongly increase the metabolic activity of colonised cells, are taken as examples.

  6. The RNA-binding protein TIAR is translocated from the nucleus to the cytoplasm during Fas-mediated apoptotic cell death.

    OpenAIRE

    Taupin, J L; Tian, Q.; Kedersha, N; Robertson, M.; Anderson, P

    1995-01-01

    We have determined the structure, intracellular localization, and tissue distribution of TIAR, a TIA-1-related RNA-binding protein. Two related isoforms of TIAR, migrating at 42 and 50 kDa, are expressed in primate cells. Unlike TIA-1, which is found in the granules of cytotoxic lymphocytes, TIAR is concentrated in the nucleus of hematopoietic and nonhematopoietic cells. Because TIAR can trigger DNA fragmentation in permeabilized thymocytes, it is a candidate effector of apoptotic cell death....

  7. Machine learning classification of cell-specific cardiac enhancers uncovers developmental subnetworks regulating progenitor cell division and cell fate specification

    OpenAIRE

    Ahmad, Shaad M.; Busser, Brian W; Huang, Di; Cozart, Elizabeth J.; Michaud, Sébastien; Zhu, Xianmin; Jeffries, Neal; Aboukhalil, Anton; Bulyk, Martha L.; Ovcharenko, Ivan; Michelson, Alan M.

    2014-01-01

    The Drosophila heart is composed of two distinct cell types, the contractile cardial cells (CCs) and the surrounding non-muscle pericardial cells (PCs), development of which is regulated by a network of conserved signaling molecules and transcription factors (TFs). Here, we used machine learning with array-based chromatin immunoprecipitation (ChIP) data and TF sequence motifs to computationally classify cell type-specific cardiac enhancers. Extensive testing of predicted enhancers at single-c...

  8. Division of labor: subsets of dorsal-appendage-forming cells control the shape of the entire tube.

    Science.gov (United States)

    Boyle, Michael J; French, Rachael L; Cosand, K Amber; Dorman, Jennie B; Kiehart, Daniel P; Berg, Celeste A

    2010-10-01

    The function of an organ relies on its form, which in turn depends on the individual shapes of the cells that create it and the interactions between them. Despite remarkable progress in the field of developmental biology, how cells collaborate to make a tissue remains an unsolved mystery. To investigate the mechanisms that determine organ structure, we are studying the cells that form the dorsal appendages (DAs) of the Drosophila melanogaster eggshell. These cells consist of two differentially patterned subtypes: roof cells, which form the outward-facing roof of the lumen, and floor cells, which dive underneath the roof cells to seal off the floor of the tube. In this paper, we present three lines of evidence that reveal a further stratification of the DA-forming epithelium. Laser ablation of only a few cells in the anterior of the region causes a disproportionately severe shortening of the appendage. Genetic alteration through the twin peaks allele of tramtrack69 (ttk(twk)), a female-sterile mutation that leads to severely shortened DAs, causes no such shortening when removed from a majority of the DA-forming cells, but rather, produces short appendages only when removed from cells in the very anterior of the tube-forming tissue. Additionally we show that heterotrimeric G-protein function is required for DA morphogenesis. Like TTK69, Gbeta 13F is not required in all DA-forming follicle cells but only in the floor and leading roof cells. The different phenotypes that result from removal of Gbeta 13F from each region demonstrate a striking division of function between different DA-forming cells. Gbeta mutant floor cells are unable to control the width of the appendage while Gbeta mutant leading roof cells fail to direct the elongation of the appendage and the convergent-extension of the roof-cell population.

  9. Computational analysis of mammalian cell division gated by a circadian clock: quantized cell cycles and cell size control.

    Science.gov (United States)

    Zámborszky, Judit; Hong, Christian I; Csikász Nagy, Attila

    2007-12-01

    Cell cycle and circadian rhythms are conserved from cyanobacteria to humans with robust cyclic features. Recently, molecular links between these two cyclic processes have been discovered. Core clock transcription factors, Bmal1 and Clock (Clk), directly regulate Wee1 kinase, which inhibits entry into the mitosis. We investigate the effect of this connection on the timing of mammalian cell cycle processes with computational modeling tools. We connect a minimal model of circadian rhythms, which consists of transcription-translation feedback loops, with a modified mammalian cell cycle model from Novak and Tyson (2004). As we vary the mass doubling time (MDT) of the cell cycle, stochastic simulations reveal quantized cell cycles when the activity of Wee1 is influenced by clock components. The quantized cell cycles disappear in the absence of coupling or when the strength of this link is reduced. More intriguingly, our simulations indicate that the circadian clock triggers critical size control in the mammalian cell cycle. A periodic brake on the cell cycle progress via Wee1 enforces size control when the MDT is quite different from the circadian period. No size control is observed in the absence of coupling. The issue of size control in the mammalian system is debatable, whereas it is well established in yeast. It is possible that the size control is more readily observed in cell lines that contain circadian rhythms, since not all cell types have a circadian clock. This would be analogous to an ultradian clock intertwined with quantized cell cycles (and possibly cell size control) in yeast. We present the first coupled model between the mammalian cell cycle and circadian rhythms that reveals quantized cell cycles and cell size control influenced by the clock.

  10. Mathematical models of tissue stem and transit target cell divisions and the risk of radiation- or smoking-associated cancer.

    Science.gov (United States)

    Little, Mark P; Hendry, Jolyon H

    2017-02-01

    There is compelling biological data to suggest that cancer arises from a series of mutations in single target cells, resulting in defects in cell renewal and differentiation processes which lead to malignancy. Because much mutagenic damage is expressed following cell division, more-rapidly renewing tissues could be at higher risk because of the larger number of cell replications. Cairns suggested that renewing tissues may reduce cancer risk by partitioning the dividing cell populations into lineages comprising infrequently-dividing long-lived stem cells and frequently-dividing short-lived daughter transit cells. We develop generalizations of three recent cancer-induction models that account for the joint maintenance and renewal of stem and transit cells, also competing processes of partially transformed cell proliferation and differentiation/apoptosis. We are particularly interested in using these models to separately assess the probabilities of mutation and development of cancer associated with "spontaneous" processes and with those linked to a specific environmental mutagen, specifically ionizing radiation or cigarette smoking. All three models demonstrate substantial variation in cancer risks, by at least 20 orders of magnitude, depending on the assumed number of critical mutations required for cancer, and the stem-cell and transition-cell mutation rates. However, in most cases the conditional probabilities of cancer being mutagen-induced range between 7-96%. The relative risks associated with mutagen exposure compared to background rates are also stable, ranging from 1.0-16.0. Very few cancers, generally Little difference is made to relative risks if competing processes of proliferation and differentiation in the partially transformed stem and transit cell population are allowed for, nor is any difference made if one assumes that transit cells require an extra mutation to confer malignancy from the number required by stem cells. The probability of a cancer

  11. Bicarbonate-sensing soluble adenylyl cyclase is present in the cell cytoplasm and nucleus of multiple shark tissues.

    Science.gov (United States)

    Roa, Jinae N; Tresguerres, Martin

    2017-01-01

    The enzyme soluble adenylyl cyclase (sAC) is directly stimulated by bicarbonate (HCO3(-)) to produce the signaling molecule cyclic adenosine monophosphate (cAMP). Because sAC and sAC-related enzymes are found throughout phyla from cyanobacteria to mammals and they regulate cell physiology in response to internal and external changes in pH, CO2, and HCO3(-), sAC is deemed an evolutionarily conserved acid-base sensor. Previously, sAC has been reported in dogfish shark and round ray gill cells, where they sense and counteract blood alkalosis by regulating the activity of V-type H(+)- ATPase. Here, we report the presence of sAC protein in gill, rectal gland, cornea, intestine, white muscle, and heart of leopard shark Triakis semifasciata Co-expression of sAC with transmembrane adenylyl cyclases supports the presence of cAMP signaling microdomains. Furthermore, immunohistochemistry on tissue sections, and western blots and cAMP-activity assays on nucleus-enriched fractions demonstrate the presence of sAC protein in and around nuclei. These results suggest that sAC modulates multiple physiological processes in shark cells, including nuclear functions.

  12. Qualitative and quantitative characteristics of the extracellular DNA delivered to the nucleus of a living cell

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    Bogachev Sergei S

    2006-10-01

    Full Text Available Abstract Background The blood plasma and other intertissue fluids usually contain a certain amount of DNA, getting there due to a natural cell death in the organism. Cells of this organism can capture the extracellular DNA, whereupon it is delivered to various cell compartments. It is hypothesized that the extracellular DNA is involved in the transfer of genetic information and its fixation in the genome of recipient cell. Results The existence of an active flow of extracellular DNA into the cell is demonstrated using human breast adenocarcinoma (MCF-7 cells as a recipient culture. The qualitative state of the DNA fragments delivered to the main cell compartments (cytoplasm and interchromosomal fraction was assessed. The extracellular DNA delivered to the cell is characterized quantitatively. Conclusion It is demonstrated that the extracellular DNA fragments in several minutes reach the nuclear space, where they are processed so that their linear size increases from about 500 bp to 10,000 bp. The amount of free extracellular DNA fragments simultaneously present in the nuclear space may reach up to 2% of the haploid genome. Using individual DNA fragments with a known molecular weight and sequence as an extracellular DNA, it is found that these fragments degrade instantly in the culture liquid in the absence of a competitor DNA and are delivered into the cell as degradants. When adding a sufficient amount of competitor DNA, the initial undegraded molecules of the DNA fragments with the known molecular weight and sequence are detectable both in the cytoplasm and nuclear space only at the zero point of experiments. The labeled precursor α-dNTP*, added to culture medium, was undetectable inside the cell in all the experiments.

  13. AHP6 inhibits cytokinin signaling to regulate the orientation of pericycle cell division during lateral root initiation.

    Directory of Open Access Journals (Sweden)

    Sofia Moreira

    Full Text Available In Arabidopsis thaliana, lateral roots (LRs initiate from anticlinal cell divisions of pericycle founder cells. The formation of LR primordia is regulated antagonistically by the phytohormones cytokinin and auxin. It has previously been shown that cytokinin has an inhibitory effect on the patterning events occurring during LR formation. However, the molecular players involved in cytokinin repression are still unknown. In a similar manner to protoxylem formation in Arabidopsis roots, in which AHP6 (ARABIDOPSIS HISTIDINE PHOSPHOTRANSFER PROTEIN 6 acts as a cytokinin inhibitor, we reveal that AHP6 also functions as a cytokinin repressor during early stages of LR development. We show that AHP6 is expressed at different developmental stages during LR formation and is required for the correct orientation of cell divisions at the onset of LR development. Moreover, we demonstrate that AHP6 influences the localization of the auxin efflux carrier PIN1, which is necessary for patterning the LR primordia. In summary, we show that the inhibition of cytokinin signaling through AHP6 is required to establish the correct pattern during LR initiation.

  14. Van Gogh and Frizzled act redundantly in the Drosophila sensory organ precursor cell to orient its asymmetric division.

    Directory of Open Access Journals (Sweden)

    José-Eduardo Gomes

    Full Text Available Drosophila sensory organ precursor cells (SOPs divide asymmetrically along the anterior-posterior (a-p body axis to generate two different daughter cells. Planar Cell Polarity (PCP regulates the a-p orientation of the SOP division. The localization of the PCP proteins Van Gogh (Vang and Frizzled (Fz define anterior and posterior apical membrane domains prior to SOP division. Here, we investigate the relative contributions of Vang, Fz and Dishevelled (Dsh, a membrane-associated protein acting downstream of Fz, in orienting SOP polarity. Genetic and live imaging analyses suggest that Dsh restricts the localization of a centrosome-attracting activity to the anterior cortex and that Vang is a target of Dsh in this process. Using a clone border assay, we provide evidence that the Vang and fz genes act redundantly in SOPs to orient its polarity axis in response to extrinsic local PCP cues. Additionally, we find that the activity of Vang is dispensable for the non-autonomous polarizing activity of fz. These observations indicate that both Vang and Fz act as cues for downstream effectors orienting the planar polarity axis of dividing SOPs.

  15. Differential expression of extracellular-signal-regulated kinase 5 (ERK5) in normal and degenerated human nucleus pulposus tissues and cells

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    Liang, Weiguo, E-mail: liangweiguo@tom.com [Guangzhou Institute of Traumatic Surgery, The Fourth Affiliated Hospital of Medical College, Jinan University, Guangzhou 510220 (China); Fang, Dejian [Guangzhou Institute of Traumatic Surgery, The Fourth Affiliated Hospital of Medical College, Jinan University, Guangzhou 510220 (China); Ye, Dongping [Guangzhou Institute of Traumatic Surgery, The Fourth Affiliated Hospital of Medical College, Jinan University, Guangzhou 510220 (China); School of Pathology and Laboratory Medicine, University of Western Australia, Crawley, Western Australia 6009 (Australia); Zou, Longqiang; Shen, Yan; Dai, Libing [Guangzhou Institute of Traumatic Surgery, The Fourth Affiliated Hospital of Medical College, Jinan University, Guangzhou 510220 (China); Xu, Jiake, E-mail: jiake.xu@uwa.edu.au [Guangzhou Institute of Traumatic Surgery, The Fourth Affiliated Hospital of Medical College, Jinan University, Guangzhou 510220 (China); School of Pathology and Laboratory Medicine, University of Western Australia, Crawley, Western Australia 6009 (Australia)

    2014-07-11

    Highlights: • ERK5 involved in NP cells. • ERK5 involved in NP tissue. • It was important modulator. - Abstract: Extracellular-signal-regulated kinase 5 (ERK5) is a member of the mitogen-activated protein kinase (MAPK) family and regulates a wide variety of cellular processes such as proliferation, differentiation, necrosis, apoptosis and degeneration. However, the expression of ERK5 and its role in degenerated human nucleus pulposus (NP) is hitherto unknown. In this study, we observed the differential expression of ERK5 in normal and degenerated human nucleus pulposus tissues by using immunohistochemical staining and Western blot. Treatment of NP cells with Pro-inflammatory cytokine, TNF-α decreased ERK5 gene expression as well as NP marker gene expression; including the type II collagen and aggrecan. Suppression of ERK5 gene expression in NP cells by ERK5 siRNA resulted in decreased gene expression of type II collagen and aggrecan. Furthermore, inhibition of ERK5 activation by BIX02188 (5 μM) decreased the gene expression of type II collagen and aggrecan in NP cells. Our results document the expression of ERK5 in degenerated nucleus pulposus tissues, and suggest a potential involvement of ERK5 in human degenerated nucleus pulposus.

  16. 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