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Sample records for cell nucleus division

  1. The bacterium endosymbiont of Crithidia deanei undergoes coordinated division with the host cell nucleus.

    Directory of Open Access Journals (Sweden)

    Maria Cristina Machado Motta

    Full Text Available In trypanosomatids, cell division involves morphological changes and requires coordinated replication and segregation of the nucleus, kinetoplast and flagellum. In endosymbiont-containing trypanosomatids, like Crithidia deanei, this process is more complex, as each daughter cell contains only a single symbiotic bacterium, indicating that the prokaryote must replicate synchronically with the host protozoan. In this study, we used light and electron microscopy combined with three-dimensional reconstruction approaches to observe the endosymbiont shape and division during C. deanei cell cycle. We found that the bacterium replicates before the basal body and kinetoplast segregations and that the nucleus is the last organelle to divide, before cytokinesis. In addition, the endosymbiont is usually found close to the host cell nucleus, presenting different shapes during the protozoan cell cycle. Considering that the endosymbiosis in trypanosomatids is a mutualistic relationship, which resembles organelle acquisition during evolution, these findings establish an excellent model for the understanding of mechanisms related with the establishment of organelles in eukaryotic cells.

  2. Nucleus-associated microtubules help determine the division plane of plant epidermal cells: avoidance of four-way junctions and the role of cell geometry.

    Science.gov (United States)

    Flanders, D J; Rawlins, D J; Shaw, P J; Lloyd, C W

    1990-04-01

    To investigate the spatial relationship between the nucleus and the cortical division site, epidermal cells were selected in which the separation between these two areas is large. Avoiding enzyme treatment and air drying, Datura stramonium cells were labeled with antitubulin antibodies and the three-dimensional aspect of the cytoskeletons was reconstructed using computer-aided optical sectioning. In vacuolated cells preparing for division, the nucleus migrates into the center of the cell, suspended by transvacuolar strands. These strands are now shown to contain continuous bundles of microtubules which bridge the nucleus to the cortex. These nucleus-radiating microtubules adopt different configurations in cells of different shape. In elongated cells with more or less parallel side walls, oblique strands radiating from the nucleus to the long side walls are presumably unstable, for they are progressively realigned into a transverse disc (the phragmosome) as broad, cortical, preprophase bands (PPBs) become tighter. The phragmosome and the PPB are both known predictors of the division plane and our observations indicate that they align simultaneously in elongated epidermal cells. These observations suggest another hypothesis: that the PPB may contain microtubules polymerized from the nuclear surface. In elongated cells, the majority of the radiating microtubules, therefore, come to anchor the nucleus in the transverse plane, consistent with the observed tendency of such cells to divide perpendicular to the long axis. In nonrectangular isodiametric epidermal cells, which approximate regular hexagons in section, the radial microtubular strands emanating from the nucleus tend to remain associated with the middle of each subtending cell wall. The strands are not reorganized into a single dominant transverse bar, but remain as a starlike array until mitosis. PPBs in these cells are not as tight; they may only be a sparse accumulation of microtubules, even forming along non

  3. 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.

  4. 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.

  5. 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

  6. Influence of cell geometry on division-plane positioning.

    Science.gov (United States)

    Minc, Nicolas; Burgess, David; Chang, Fred

    2011-02-01

    The spatial organization of cells depends on their ability to sense their own shape and size. Here, we investigate how cell shape affects the positioning of the nucleus, spindle and subsequent cell division plane. To manipulate geometrical parameters in a systematic manner, we place individual sea urchin eggs into microfabricated chambers of defined geometry (e.g., triangles, rectangles, and ellipses). In each shape, the nucleus is positioned at the center of mass and is stretched by microtubules along an axis maintained through mitosis and predictive of the future division plane. We develop a simple computational model that posits that microtubules sense cell geometry by probing cellular space and orient the nucleus by exerting pulling forces that scale to microtubule length. This model quantitatively predicts division-axis orientation probability for a wide variety of cell shapes, even in multicellular contexts, and estimates scaling exponents for length-dependent microtubule forces. PMID:21295701

  7. 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.

  8. 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. PMID:27505160

  9. 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.

  10. Actomyosin contractility rotates the cell nucleus

    CERN Document Server

    Kumar, Abhishek; Sumit, Madhuresh; Ramaswamy, Sriram; Shivashankar, G V

    2013-01-01

    The nucleus of the eukaryotic cell functions amidst active cytoskeletal filaments, but its response to the stresses carried by these filaments is largely unexplored. We report here the results of studies of the translational and rotational dynamics of the nuclei of single fibroblast cells, with the effects of cell migration suppressed by plating onto fibronectin-coated micro-fabricated patterns. Patterns of the same area but different shapes and/or aspect ratio were used to study the effect of cell geometry on the dynamics. On circles, squares and equilateral triangles, the nucleus undergoes persistent rotational motion, while on high-aspect-ratio rectangles of the same area it moves only back and forth. The circle and the triangle showed respectively the largest and the smallest angular speed. We show that our observations can be understood through a hydrodynamic approach in which the nucleus is treated as a highly viscous inclusion residing in a less viscous fluid of orientable filaments endowed with active...

  11. Asymmetric cell division: a persistent issue?

    OpenAIRE

    Aakre, Christopher D.; Laub, Michael T.

    2012-01-01

    Heterogeneity within a clonal population of cells can increase survival in the face of environmental stress. In a recent issue of Science, Aldridge et al. (2012) demonstrate that cell division in mycobacteria is asymmetric, producing daughter cells that differ in size, growth rate, and susceptibility to antibiotics.

  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. Physical role for the nucleus in cell migration.

    Science.gov (United States)

    Fruleux, Antoine; Hawkins, Rhoda J

    2016-09-14

    Cell migration is important for the function of many eukaryotic cells. Recently the nucleus has been shown to play an important role in cell motility. After giving an overview of cell motility mechanisms we review what is currently known about the mechanical properties of the nucleus and the connections between it and the cytoskeleton. We also discuss connections to the extracellular matrix and mechanotransduction. We identify key physical roles of the nucleus in cell migration. PMID:27406341

  14. Physical role for the nucleus in cell migration

    Science.gov (United States)

    Fruleux, Antoine; Hawkins, Rhoda J.

    2016-09-01

    Cell migration is important for the function of many eukaryotic cells. Recently the nucleus has been shown to play an important role in cell motility. After giving an overview of cell motility mechanisms we review what is currently known about the mechanical properties of the nucleus and the connections between it and the cytoskeleton. We also discuss connections to the extracellular matrix and mechanotransduction. We identify key physical roles of the nucleus in cell migration.

  15. 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.

  16. Bacterial cell division proteins as antibiotic targets

    NARCIS (Netherlands)

    T. den Blaauwen; J.M. Andreu; O. Monasterio

    2014-01-01

    Proteins involved in bacterial cell division often do not have a counterpart in eukaryotic cells and they are essential for the survival of the bacteria. The genetic accessibility of many bacterial species in combination with the Green Fluorescence Protein revolution to study localization of protein

  17. 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...

  18. Rab24 is required for normal cell division.

    Science.gov (United States)

    Militello, Rodrigo D; Munafó, Daniela B; Berón, Walter; López, Luis A; Monier, Solange; Goud, Bruno; Colombo, María I

    2013-05-01

    Rab24 is an atypical member of the Rab GTPase family whose distribution in interphase cells has been characterized; however, its function remains largely unknown. In this study, we have analyzed the distribution of Rab24 throughout cell division. We have observed that Rab24 was located at the mitotic spindle in metaphase, at the midbody during telophase and in the furrow during cytokinesis. We have also observed partial co-localization of Rab24 and tubulin and demonstrated its association to microtubules. Interestingly, more than 90% of transiently transfected HeLa cells with Rab24 presented abnormal nuclear connections (i.e., chromatin bridges). Furthermore, in CHO cells stably transfected with GFP-Rab24wt, we observed a large percentage of binucleated and multinucleated cells. In addition, these cells presented an extremely large size and multiple failures in mitosis, as aberrant spindle formation (metaphase), delayed chromosomes (telophase) and multiple cytokinesis. A marked increase in binucleated, multinucleated and multilobulated nucleus formation was observed in HeLa cells depleted of Rab24. We also present evidence that a fraction of Rab24 associates with microtubules. In addition, Rab24 knock down resulted in misalignment of chromosomes and abnormal spindle formation in metaphase leading to the appearance of delayed chromosomes during late telophase and failures in cytokinesis. Our findings suggest that an adequate level of Rab24 is necessary for normal cell division. In summary, Rab24 modulates several mitotic events, including chromosome segregation and cytokinesis, perhaps through the interaction with microtubules. PMID:23387408

  19. Suprachiasmatic Nucleus: Cell Autonomy and Network Properties

    Science.gov (United States)

    Welsh, David K.; Takahashi, Joseph S.; Kay, Steve A.

    2013-01-01

    The suprachiasmatic nucleus (SCN) is the primary circadian pacemaker in mammals. Individual SCN neurons in dispersed culture can generate independent circadian oscillations of clock gene expression and neuronal firing. However, SCN rhythmicity depends on sufficient membrane depolarization and levels of intracellular calcium and cAMP. In the intact SCN, cellular oscillations are synchronized and reinforced by rhythmic synaptic input from other cells, resulting in a reproducible topographic pattern of distinct phases and amplitudes specified by SCN circuit organization. The SCN network synchronizes its component cellular oscillators, reinforces their oscillations, responds to light input by altering their phase distribution, increases their robustness to genetic perturbations, and enhances their precision. Thus, even though individual SCN neurons can be cell-autonomous circadian oscillators, neuronal network properties are integral to normal function of the SCN. PMID:20148688

  20. Polarity in Stem Cell Division: Asymmetric Stem Cell Division in Tissue Homeostasis

    OpenAIRE

    Yamashita, Yukiko M; Yuan, Hebao; Cheng, Jun; Hunt, Alan J.

    2010-01-01

    Many adult stem cells divide asymmetrically to balance self-renewal and differentiation, thereby maintaining tissue homeostasis. Asymmetric stem cell divisions depend on asymmetric cell architecture (i.e., cell polarity) within the cell and/or the cellular environment. In particular, as residents of the tissues they sustain, stem cells are inevitably placed in the context of the tissue architecture. Indeed, many stem cells are polarized within their microenvironment, or the stem cell niche, a...

  1. Regulation of cell division in higher plants

    Energy Technology Data Exchange (ETDEWEB)

    Jacobs, T.W.

    1992-01-01

    Cell division is arguably the most fundamental of all developmental processes. In higher plants, mitotic activity is largely confined to foci of patterned cell divisions called meristems. From these perpetually embryonic tissues arise the plant's essential organs of light capture, support, protection and reproduction. Once an adequate understanding of plant cell mitotic regulation is attained, unprecedented opportunities will ensue for analyzing and genetically controlling diverse aspects of development, including plant architecture, leaf shape, plant height, and root depth. The mitotic cycle in a variety of model eukaryotic systems in under the control of a regulatory network of striking evolutionary conservation. Homologues of the yeast cdc2 gene, its catalytic product, p34, and the cyclin regulatory subunits of the MPF complex have emerged as ubiquitous mitotic regulators. We have cloned cdc2-like and cyclin genes from pea. As in other eukaryotic model systems, p34 of Pisum sativum is a subunit of a high molecular weight complex which binds the fission yeast p13 protein and displays histone H1 kinase activity in vitro. Our primary objective in this study is to gain baseline information about the regulation of this higher plant cell division control complex in non-dividing, differentiated cells as well as in synchronous and asynchronous mitotic cells. We are investigating cdc2 and cyclin expression at the levels of protein abundance, protein phosphorylation and quaternary associations.

  2. 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.

  3. 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. PMID:23248201

  4. Cell adhesion in regulation of asymmetric stem cell division

    OpenAIRE

    Yamashita, Yukiko M

    2010-01-01

    Adult stem cells inevitably communicate with their cellular neighbors within the tissues they sustain. Indeed, such communication, particularly with components of the stem cell niche, is essential for many aspects of stem cell behavior, including the maintenance of stem cell identity and asymmetric cell division. Cell adhesion mediates this communication by placing stem cells in close proximity to the signaling source and by providing a polarity cue that orients stem cells. Here, I review the...

  5. 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

  6. 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.

  7. 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

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

    International Nuclear Information System (INIS)

    Seed germination implies metabolic reactivation, synthesis of macromolecules and onset of cell division. During maize germination, meristematic tissues of embryos re-initiate cell division asynchronically. Since auxins are known to stimulate cell division, they asked how auxins might regulate cell cycle re-initiation. Embryonic tissues were incubated with and without auxins. A pulse of either 3H-thymidine or 32P-ortophosphate was given to the tissues. Mitotic indexes were determined and % of labeled mitotic cells recorded. Results indicated that meristematic cells re-initiate cell division either from G1 or G2 phases. Auxin stimulated differentially the cell division process of these cells. 32P incorporation into cytoplasmic or nucleic histones was measured. Auxins stimulated this incorporation. Active turnover of histone phosphorylation occurred simultaneously to the cell division process. It is suggested that auxins might regulate the cell cycle by phosphorylation-dephosphorylation of histones

  9. 3-(Benzodioxan-2-ylmethoxy)-2,6-difluorobenzamides bearing hydrophobic substituents at the 7-position of the benzodioxane nucleus potently inhibit methicillin-resistant Sa and Mtb cell division.

    Science.gov (United States)

    Straniero, Valentina; Pallavicini, Marco; Chiodini, Giuseppe; Zanotto, Carlo; Volontè, Luca; Radaelli, Antonia; Bolchi, Cristiano; Fumagalli, Laura; Sanguinetti, Maurizio; Menchinelli, Giulia; Delogu, Giovanni; Battah, Basem; De Giuli Morghen, Carlo; Valoti, Ermanno

    2016-09-14

    Lipophilic substituents at benzodioxane C (7) of 3-(benzodioxan-2-ylmethoxy)-2,6-difluorobenzamide improve the antibacterial activity against methicillin-resistant Staphylococcus aureus strains to MIC values in the range of 0.2-2.5 μg/mL, whereas hydrophilic substituents at the same position and modifications at the benzodioxane substructure, excepting for replacement with 2-cromanyl, are deleterious. Some of the lead compounds also exhibit good activity against Mtb. Parallel SARs to those of 3-(2-benzothiazol-2-ylmethoxy)-2,6-difluorobenzamide, well known FtsZ inhibitor, and cells alterations typical of FtsZ inhibition indicate such a protein as the target of these potent antibacterial benzodioxane-benzamides. PMID:27191617

  10. 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

  11. 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.

  12. Polarised cells, polarised views: Asymmetric cell division in hematopoietic cells.

    Directory of Open Access Journals (Sweden)

    Kim ePham

    2014-02-01

    Full Text Available It has long been recognised that alterations in cell shape and polarity play important roles in coordinating lymphocyte functions. In the last decade a new aspect of lymphocyte polarity, termed Asymmetric Cell Division (ACD, has attracted much attention. ACD has previously been shown to dictate or influence many aspects of development in model organisms such as the worm and the fly, and to be disrupted in disease. Recent observations that ACD also occurs in lymphocytes led to exciting speculations that ACD might influence lymphocyte differentiation and function, and leukaemia. However, dissecting the role that ACD might play in these activities is not straightforward, and the evidence to date for a functional role in lymphocyte fate determination has been controversial. In this review, we discuss the evidence to date for ACD in lymphocytes, and how it might influence lymphocyte fate. We also discuss current gaps in our knowledge, and suggest approaches to definitively test the physiological role of ACD in lymphocytes.

  13. 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...

  14. 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.

  15. Estimated Radiation on Mars, Hits per Cell Nucleus

    Science.gov (United States)

    2002-01-01

    This global map of Mars shows estimates for amounts of high-energy-particle cosmic radiation reaching the surface, a serious health concern for any future human exploration of the planet.The estimates are based on cosmic-radiation measurements made on the way to Mars by the Mars radiation environment experiment, an instrument on NASA's 2001 Mars Odyssey spacecraft, plus information about Mars' surface elevations from the laser altimeter instrument on NASA's Mars Global Surveyor. The areas of Mars expected to have least radiation are where elevation is lowest, because those areas have more atmosphere above them to block out some of the radiation. Earth's thick atmosphere shields us from most cosmic radiation, but Mars has a much thinner atmosphere than Earth does.Colors in the map refer to the estimated average number of times per year each cell nucleus in a human there would be hit by a high-energy cosmic ray particle. The range is generally from two hits (color-coded green), a moderate risk level, to eight hits (coded red), a high risk level.NASA's Jet Propulsion Laboratory, Pasadena, Calif. manages the 2001 Mars Odyssey and Mars Global Surveyor missions for NASA's Office of Space Science, Washington D.C. The Mars radiation environment experiment was developed by NASA's Johnson Space Center. Lockheed Martin Astronautics, Denver, is the prime contractor for Odyssey, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  16. 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.

  17. Mechanisms of daughter cell-size control during cell division.

    Science.gov (United States)

    Kiyomitsu, Tomomi

    2015-05-01

    Daughter cell size is tightly regulated during cell division. In animal cells, the position of the anaphase spindle specifies the cell cleavage site to dictate the relative size of the daughter cells. Although spindle orientation is regulated by dynein-dependent cortical pulling forces exerted on astral microtubules in many cell types, it was unclear how these forces are precisely regulated to center or displace the spindle. Recently, intrinsic signals derived from chromosomes or spindle poles have been demonstrated to regulate dynein-dependent pulling forces in symmetrically dividing cells. Unexpectedly, myosin-dependent contractile forces have also been shown to control spindle position by altering the cellular boundaries during anaphase. In this review, I discuss how dynein- and myosin-dependent forces are coordinately regulated to control daughter cell size. PMID:25548067

  18. 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.

  19. 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...

  20. 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.

  1. 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.

  2. 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.

  3. Oriented cell division shapes carnivorous pitcher leaves of Sarracenia purpurea.

    Science.gov (United States)

    Fukushima, Kenji; Fujita, Hironori; Yamaguchi, Takahiro; Kawaguchi, Masayoshi; Tsukaya, Hirokazu; Hasebe, Mitsuyasu

    2015-01-01

    Complex morphology is an evolutionary outcome of phenotypic diversification. In some carnivorous plants, the ancestral planar leaf has been modified to form a pitcher shape. However, how leaf development was altered during evolution remains unknown. Here we show that the pitcher leaves of Sarracenia purpurea develop through cell division patterns of adaxial tissues that are distinct from those in bifacial and peltate leaves, subsequent to standard expression of adaxial and abaxial marker genes. Differences in the orientation of cell divisions in the adaxial domain cause bifacial growth in the distal region and adaxial ridge protrusion in the middle region. These different growth patterns establish pitcher morphology. A computer simulation suggests that the cell division plane is critical for the pitcher morphogenesis. Our results imply that tissue-specific changes in the orientation of cell division underlie the development of a morphologically complex leaf. PMID:25774486

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

    Science.gov (United States)

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

    2016-01-01

    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. PMID:27456660

  5. 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.

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

    DEFF Research Database (Denmark)

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

    2008-01-01

    Formation of the Z ring is the first known event in bacterial cell division. However, it is not yet known how the assembly and contraction of the Z ring is regulated. Here, we identify a novel cell division factor ZapB in Escherichia coli that simultaneously stimulates Z ring assembly and cell...... division. Deletion of zapB resulted in delayed cell division and the formation of ectopic Z rings and spirals whereas overexpression of ZapB resulted in nucleoid condensation and aberrant cell divisions. Localization of ZapB to the divisome depended on FtsZ but not FtsA, ZipA or FtsI and ZapB interacted...... 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...

  8. 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.

  9. 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.

  10. 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.

  11. Biased DNA Segregation during Stem Cell Division

    OpenAIRE

    Anversa, Piero; Leri, Annarosa; Kajstura, Jan

    2012-01-01

    Adult skeletal muscle stem cells are a heterogeneous cell population characterized by a small subset of undifferentiated cells that express at high level the paired/homeodomain gene Pax7. This category of satellite cells divides predominantly by asymmetric chromatid segregation generating a daughter cell that carries the mother DNA and retains stem cell property, and a daughter cell that inherits the newly-synthesized DNA and acquires the myocyte lineage.1

  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. Physical association between a novel plasma-membrane structure and centrosome orients cell division

    Science.gov (United States)

    Negishi, Takefumi; Miyazaki, Naoyuki; Murata, Kazuyoshi; Yasuo, Hitoyoshi; Ueno, Naoto

    2016-01-01

    In the last mitotic division of the epidermal lineage in the ascidian embryo, the cells divide stereotypically along the anterior-posterior axis. During interphase, we found that a unique membrane structure invaginates from the posterior to the centre of the cell, in a microtubule-dependent manner. The invagination projects toward centrioles on the apical side of the nucleus and associates with one of them. Further, a cilium forms on the posterior side of the cell and its basal body remains associated with the invagination. A laser ablation experiment suggests that the invagination is under tensile force and promotes the posterior positioning of the centrosome. Finally, we showed that the orientation of the invaginations is coupled with the polarized dynamics of centrosome movements and the orientation of cell division. Based on these findings, we propose a model whereby this novel membrane structure orchestrates centrosome positioning and thus the orientation of cell division axis. DOI: http://dx.doi.org/10.7554/eLife.16550.001 PMID:27502556

  14. 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

  15. Size-independent symmetric division in extraordinarily long cells

    NARCIS (Netherlands)

    N. Pende; N. Leisch; H.R. Gruber-Vodicka; N.R. Heindl; J. Ott; T. den Blaauwen; S. Bulgheresi

    2014-01-01

    Two long-standing paradigms in biology are that cells belonging to the same population exhibit little deviation from their average size and that symmetric cell division is size limited. Here, ultrastructural, morphometric and immunocytochemical analyses reveal that two Gammaproteobacteria attached t

  16. 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...

  17. 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).

  18. 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

  19. 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.

  20. Microtubule networks for plant cell division.

    Science.gov (United States)

    de Keijzer, Jeroen; Mulder, Bela M; Janson, Marcel E

    2014-09-01

    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 cell plate, which is constructed by localized deposition of membrane and cell wall material. Construction starts in the centre of the cell at the locus of the mitotic spindle and continues radially towards the existing plasma membrane. Finally the membrane of the cell plate and plasma membrane fuse to form two individual plasma membranes. Two microtubule-based cytoskeletal networks, the phragmoplast and the pre-prophase band (PPB), jointly control cytokinesis in plants. The bipolar microtubule array of the phragmoplast regulates cell plate deposition towards a cortical position that is templated by the ring-shaped microtubule array of the PPB. In contrast to most animal cells, plants do not use centrosomes as foci of microtubule growth initiation. Instead, plant microtubule networks are striking examples of self-organizing systems that emerge from physically constrained interactions of dispersed microtubules. Here we will discuss how microtubule-based activities including growth, shrinkage, severing, sliding, nucleation and bundling interrelate to jointly generate the required ordered structures. Evidence mounts that adapter proteins sense the local geometry of microtubules to locally modulate the activity of proteins involved in microtubule growth regulation and severing. Many of the proteins and mechanisms involved have roles in other microtubule assemblies as well, bestowing broader relevance to insights gained from plants. PMID:25136380

  1. Activation of cell divisions in legume nodulation

    DEFF Research Database (Denmark)

    Nadzieja, Marcin

    2016-01-01

    Leguminous plants engage into symbiotic relationships with soil bacteria, rhizobia, and develop root nodules. This process initiates with recognition of bacteria derived signalling molecules called nod factors. The subsequent events lead to symbiotic infection and, occurring in parallel, de novo...... was shown to require auxin signalling. Cytokinin, in contrast, exert a negative regulation of bacterial entry into the root. During organogenesis, auxin and cytokinin maxima are known to accompany nodule primordia development and together regulate progression through the cell cycle. Moreover, application...... observations of the DR5 reporter showed activity maxima situated in pericycle and endodermis cells specifically below infection sites. Using gravitropic bending auxin responses in the pericycle could be induced, specifically on the outer side of the gravitropic bend in uninoculated plants. When conducted...

  2. 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

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

    Asami, Koji; Sekine, Katsuhisa

    2007-02-01

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

  5. Regulation of cell division in higher plants. Progress report

    Energy Technology Data Exchange (ETDEWEB)

    Jacobs, T.W.

    1992-07-01

    Cell division is arguably the most fundamental of all developmental processes. In higher plants, mitotic activity is largely confined to foci of patterned cell divisions called meristems. From these perpetually embryonic tissues arise the plant`s essential organs of light capture, support, protection and reproduction. Once an adequate understanding of plant cell mitotic regulation is attained, unprecedented opportunities will ensue for analyzing and genetically controlling diverse aspects of development, including plant architecture, leaf shape, plant height, and root depth. The mitotic cycle in a variety of model eukaryotic systems in under the control of a regulatory network of striking evolutionary conservation. Homologues of the yeast cdc2 gene, its catalytic product, p34, and the cyclin regulatory subunits of the MPF complex have emerged as ubiquitous mitotic regulators. We have cloned cdc2-like and cyclin genes from pea. As in other eukaryotic model systems, p34 of Pisum sativum is a subunit of a high molecular weight complex which binds the fission yeast p13 protein and displays histone H1 kinase activity in vitro. Our primary objective in this study is to gain baseline information about the regulation of this higher plant cell division control complex in non-dividing, differentiated cells as well as in synchronous and asynchronous mitotic cells. We are investigating cdc2 and cyclin expression at the levels of protein abundance, protein phosphorylation and quaternary associations.

  6. 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.

  7. 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.

  8. 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

  9. Zero Crossing Edge Detection and Contour Tracing for Segmentation of Cervical Cell Nucleus .

    Directory of Open Access Journals (Sweden)

    B.V. Ramesh

    1993-07-01

    Full Text Available To automate the process of screening of normal and abnormal cervical cells, there is a need for automatic segmentation of the nucleus of these cells. This paper presents an algorithm using the Laplacian of Gaussian operator and contour tracer to segment the nucleus from the background. The algorithm has been tested on different kinds of images of cervical cells.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Mitosis in diatoms: rediscovering an old model for cell division.

    Science.gov (United States)

    De Martino, Alessandra; Amato, Alberto; Bowler, Chris

    2009-08-01

    Diatoms are important protists that generate one fifth of the oxygen produced annually on earth. These aquatic organisms likely derived from a secondary endosymbiosis event, and they display peculiar genomic and structural features that reflect their chimeric origin. Diatoms were one of the first models of cell division and these early studies revealed a range of interesting features including a unique acentriolar microtubule-organising centre. Unfortunately, almost nothing is known at the molecular level, in contrast to the advances in other experimental organisms. Recently the full genome sequences of two diatoms have been annotated and molecular tools have been developed. These resources offer new possibilities to re-investigate the mechanisms of cell division in diatoms by recruiting information from more intensively studied organisms. A renaissance of the topic is further justified by the current interest in diatoms as a source of biofuels and for understanding massive diatom proliferation events in response to environmental stimuli. PMID:19572334

  15. Cell Division Behaviour in a Heterogeneous Swarm Environment

    OpenAIRE

    Erskine, Adam; Herrmann, J. Michael

    2013-01-01

    We present a system of virtual particles that interact using simple kinetic rules. It is known that heterogeneous mixtures of particles are producing particularly interesting behaviours. Here we present a two-species swarm in which a behaviour emerges that resembles cell division. We show that the dividing behaviour exists across a narrow but finite band of parameters and for a wide range of population sizes. In a two dimensional environment the swarm's characteristics and dynamism manifests ...

  16. 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

  17. 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

  18. Patterns of Stem Cell Divisions Contribute to Plant Longevity.

    Science.gov (United States)

    Burian, Agata; Barbier de Reuille, Pierre; Kuhlemeier, Cris

    2016-06-01

    The lifespan of plants ranges from a few weeks in annuals to thousands of years in trees. It is hard to explain such extreme longevity considering that DNA replication errors inevitably cause mutations. Without purging through meiotic recombination, the accumulation of somatic mutations will eventually result in mutational meltdown, a phenomenon known as Muller's ratchet. Nevertheless, the lifespan of trees is limited more often by incidental disease or structural damage than by genetic aging. The key determinants of tree architecture are the axillary meristems, which form in the axils of leaves and grow out to form branches. The number of branches is low in annual plants, but in perennial plants iterative branching can result in thousands of terminal branches. Here, we use stem cell ablation and quantitative cell-lineage analysis to show that axillary meristems are set aside early, analogous to the metazoan germline. While neighboring cells divide vigorously, axillary meristem precursors maintain a quiescent state, with only 7-9 cell divisions occurring between the apical and axillary meristem. During iterative branching, the number of branches increases exponentially, while the number of cell divisions increases linearly. Moreover, computational modeling shows that stem cell arrangement and positioning of axillary meristems distribute somatic mutations around the main shoot, preventing their fixation and maximizing genetic heterogeneity. These features slow down Muller's ratchet and thereby extend lifespan. PMID:27161504

  19. Differential Management of the Replication Terminus Regions of the Two Vibrio cholerae Chromosomes during Cell Division

    OpenAIRE

    Gaëlle Demarre; Elisa Galli; Leila Muresan; Evelyne Paly; Ariane David; Christophe Possoz; François-Xavier Barre

    2014-01-01

    The replication terminus region (Ter) of the unique chromosome of most bacteria locates at mid-cell at the time of cell division. In several species, this localization participates in the necessary coordination between chromosome segregation and cell division, notably for the selection of the division site, the licensing of the division machinery assembly and the correct alignment of chromosome dimer resolution sites. The genome of Vibrio cholerae, the agent of the deadly human disease choler...

  20. 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.

  1. 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.

  2. 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.

  3. Lessons from development: A role for asymmetric stem cell division in cancer

    OpenAIRE

    Powell, Anne E.; Shung, Chia-Yi; Saylor, Katherine W.; Müllendorf, Karin A.; Weiss, Joseph B.; Wong, Melissa H.

    2009-01-01

    Asymmetric stem cell division has emerged as a major regulatory mechanism for physiologic control of stem cell numbers. Reinvigoration of the cancer stem cell theory suggests that tumorigenesis may be regulated by maintaining the balance between asymmetric and symmetric cell division. Therefore, mutations affecting this balance could result in aberrant expansion of stem cells. Although a number of molecules have been implicated in regulation of asymmetric stem cell division, here, we highligh...

  4. 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

  5. Thermodynamic pathways to genome spatial organization in the cell nucleus.

    Science.gov (United States)

    Nicodemi, Mario; Prisco, Antonella

    2009-03-18

    The architecture of the eukaryotic genome is characterized by a high degree of spatial organization. Chromosomes occupy preferred territories correlated to their state of activity and, yet, displace their genes to interact with remote sites in complex patterns requiring the orchestration of a huge number of DNA loci and molecular regulators. Far from random, this organization serves crucial functional purposes, but its governing principles remain elusive. By computer simulations of a statistical mechanics model, we show how architectural patterns spontaneously arise from the physical interaction between soluble binding molecules and chromosomes via collective thermodynamics mechanisms. Chromosomes colocalize, loops and territories form, and find their relative positions as stable thermodynamic states. These are selected by thermodynamic switches, which are regulated by concentrations/affinity of soluble mediators and by number/location of their attachment sites along chromosomes. Our thermodynamic switch model of nuclear architecture, thus, explains on quantitative grounds how well-known cell strategies of upregulation of DNA binding proteins or modification of chromatin structure can dynamically shape the organization of the nucleus. PMID:19289043

  6. 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.

  7. Mathematical model of the cell division cycle of fission yeast

    Science.gov (United States)

    Novak, Bela; Pataki, Zsuzsa; Ciliberto, Andrea; Tyson, John J.

    2001-03-01

    Much is known about the genes and proteins controlling the cell cycle of fission yeast. Can these molecular components be spun together into a consistent mechanism that accounts for the observed behavior of growth and division in fission yeast cells? To answer this question, we propose a mechanism for the control system, convert it into a set of 14 differential and algebraic equations, study these equations by numerical simulation and bifurcation theory, and compare our results to the physiology of wild-type and mutant cells. In wild-type cells, progress through the cell cycle (G1→S→G2→M) is related to cyclic progression around a hysteresis loop, driven by cell growth and chromosome alignment on the metaphase plate. However, the control system operates much differently in double-mutant cells, wee1- cdc25Δ, which are defective in progress through the latter half of the cell cycle (G2 and M phases). These cells exhibit "quantized" cycles (interdivision times clustering around 90, 160, and 230 min). We show that these quantized cycles are associated with a supercritical Hopf bifurcation in the mechanism, when the wee1 and cdc25 genes are disabled.

  8. Omics and modeling approaches approaches for understanding regulation of asymmetric cell divisions in Arabidopsis and other angiosperm plants.

    NARCIS (Netherlands)

    Kajala, K.; Ramakrishna, A.; Fisher, A.; Bergmann, D.C.; Smet, De I.; Sozzani, R.; Weijers, D.; Brady, S.M.

    2014-01-01

    Background Asymmetric cell divisions are formative divisions that generate daughter cells of distinct identity. These divisions are coordinated by either extrinsic (‘niche-controlled’) or intrinsic regulatory mechanisms and are fundamentally important in plant development. Scope This review describe

  9. Huntingtin regulates mammary stem cell division and differentiation.

    Science.gov (United States)

    Elias, Salah; Thion, Morgane S; Yu, Hua; Sousa, Cristovao Marques; Lasgi, Charlène; Morin, Xavier; Humbert, Sandrine

    2014-04-01

    Little is known about the mechanisms of mitotic spindle orientation during mammary gland morphogenesis. Here, we report the presence of huntingtin, the protein mutated in Huntington's disease, in mouse mammary basal and luminal cells throughout mammogenesis. Keratin 5-driven depletion of huntingtin results in a decreased pool and specification of basal and luminal progenitors, and altered mammary morphogenesis. Analysis of mitosis in huntingtin-depleted basal progenitors reveals mitotic spindle misorientation. In mammary cell culture, huntingtin regulates spindle orientation in a dynein-dependent manner. Huntingtin is targeted to spindle poles through its interaction with dynein and promotes the accumulation of NUMA and LGN. Huntingtin is also essential for the cortical localization of dynein, dynactin, NUMA, and LGN by regulating their kinesin 1-dependent trafficking along astral microtubules. We thus suggest that huntingtin is a component of the pathway regulating the orientation of mammary stem cell division, with potential implications for their self-renewal and differentiation properties. PMID:24749073

  10. Chromokinesin: Kinesin superfamily regulating cell division through chromosome and spindle.

    Science.gov (United States)

    Zhong, Ai; Tan, Fu-Qing; Yang, Wan-Xi

    2016-09-01

    Material transportation is essential for appropriate cellular morphology and functions, especially during cell division. As a motor protein moving along microtubules, kinesin has several intracellular functions. Many kinesins play important roles in chromosome condensation and separation and spindle organization during the cell cycle. Some of them even can directly bind to chromosomes, as a result, these proteins are called chromokinesins. Kinesin-4 and kinesin-10 family are two major families of chromokinesin and many members can regulate some processes, both in mitosis and meiosis. Their functions have been widely studied. Here, we summarize current knowledge about known chromokinesins and introduce their intracellular features in accordance with different families. Furthermore, we have also introduced some new-found but unconfirmed kinesins which may have a relationship with chromosomes or the cell cycle. PMID:27196062

  11. Huntingtin Regulates Mammary Stem Cell Division and Differentiation

    Directory of Open Access Journals (Sweden)

    Salah Elias

    2014-04-01

    Full Text Available Little is known about the mechanisms of mitotic spindle orientation during mammary gland morphogenesis. Here, we report the presence of huntingtin, the protein mutated in Huntington’s disease, in mouse mammary basal and luminal cells throughout mammogenesis. Keratin 5-driven depletion of huntingtin results in a decreased pool and specification of basal and luminal progenitors, and altered mammary morphogenesis. Analysis of mitosis in huntingtin-depleted basal progenitors reveals mitotic spindle misorientation. In mammary cell culture, huntingtin regulates spindle orientation in a dynein-dependent manner. Huntingtin is targeted to spindle poles through its interaction with dynein and promotes the accumulation of NUMA and LGN. Huntingtin is also essential for the cortical localization of dynein, dynactin, NUMA, and LGN by regulating their kinesin 1-dependent trafficking along astral microtubules. We thus suggest that huntingtin is a component of the pathway regulating the orientation of mammary stem cell division, with potential implications for their self-renewal and differentiation properties.

  12. Role of SCHIZORIZA in asymmetric cell division, cell fate segregation and specification in Arabidopsis root development

    NARCIS (Netherlands)

    Jansweijer, V.M.A.

    2013-01-01

    Multicellular organisms develop their large variety of cell types from just one single cell, the zygote. Both plants and animals use asymmetric cell division to establish a multicellular body plan How different cell and tissue types are determined, how patterns are created and maintained, and which

  13. Counting human somatic cell replications: methylation mirrors endometrial stem cell divisions.

    Science.gov (United States)

    Kim, Jung Yeon; Tavaré, Simon; Shibata, Darryl

    2005-12-01

    Cell proliferation may be altered in many diseases, but it is uncertain exactly how to measure total numbers of divisions. Although it is impossible to count every division directly, potentially total numbers of stem cell divisions since birth may be inferred from numbers of somatic errors. The idea is that divisions are surreptitiously recorded by random errors that occur during replication. To test this "molecular clock" hypothesis, epigenetic errors encoded in certain methylation patterns were counted in glands from 30 uteri. Endometrial divisions can differ among women because of differences in estrogen exposures or numbers of menstrual cycles. Consistent with an association between mitotic age and methylation, there was an age-related increase in methylation with stable levels after menopause, and significantly less methylation was observed in lean or older multiparous women. Methylation patterns were diverse and more consistent with niche rather than immortal stem cell lineages. There was no evidence for decreased stem cell survival with aging. An ability to count lifetime numbers of stem cell divisions covertly recorded by random replication errors provides new opportunities to link cell proliferation with aging and cancer. PMID:16314580

  14. Effects of brevetoxins on murine myeloma SP2/O cells: aberrant cellular division.

    Science.gov (United States)

    Han, Thomas K; Derby, Melissa; Martin, Dean F; Wright, Scott D; Dao, My Lien

    2003-01-01

    Massive deaths of manatees (Trichechus manatus latirostris) during the red tide seasons have been attributed to brevetoxins produced by the dinoflagellate Karenia brevis (formerly Ptychodiscus breve and Gymnodinium breve). Although these toxins have been found in macrophages and lymphocytes in the lung, liver, and secondary lymphoid tissues of these animals, the molecular mechanisms of brevetoxicosis have not yet been identified. To investigate the effects of brevetoxins on immune cells, a murine myeloma cell line (SP2/O) was used as a model for in vitro studies. By adding brevetoxins to cultures of the SP2/O cells at concentrations ranging from 20 to 600 ng/ml, an apparent increase in proliferation was observed at around 2 hours post challenge as compared to the unchallenged cell cultures. This was followed by a drop in cell number at around 3 hours, suggesting an aberrant effect of brevetoxins on cellular division, the cells generated at 2 hours being apparently short-lived. In situ immunochemical staining of the SP2/O cells at 1 and 2 hour post challenge showed an accumulation of the toxins in the nucleus. A 21-kDa protein was subsequently isolated from the SP2/O cells as having brevetoxin-binding properties, and immunologically identified as p21, a nuclear factor known to down-regulate cellular proliferation through inhibition of cyclin-dependent kinases. These data are the first on a possible effect of brevetoxins on the cell cycle via binding to p21, a phenomenon that needs to be further investigated and validated in normal immune cells. PMID:12745987

  15. Internal dynamics of a living cell nucleus investigated by dynamic light scattering

    Science.gov (United States)

    Suissa, M.; Place, C.; Goillot, E.; Freyssingeas, E.

    2008-08-01

    Recent progresses in cellular biology have shown that the nucleus of a living cell is a structured integration of many functional domains with a complex spatial organization. This organization, as well as molecular and biochemical processes, is time regulated. In the past years many investigations have been performed using fluorescent microscopy techniques to study the internal dynamics of the nucleus of a living cell. These investigations, however, have never focussed on the global internal dynamics of the nucleus, which is still unknown. In this article we present an original light scattering experimental device that we built to investigate this dynamics during biological processes. By means of this experimental set-up, we investigated the global dynamics of the nucleus of a living cell treated with a DNA replication inhibitor. This dynamics presents different and independent kinds of relaxation well separated in time that vary as a function of the cell cycle phases.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. From HeLa cell division to infectious diarrhoea

    Energy Technology Data Exchange (ETDEWEB)

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

    1990-09-01

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

  3. 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.

  4. 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.

  5. 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.

  6. 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. PMID:25350732

  7. 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.

  8. 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.

  9. 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.

  10. 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. PMID:27575162

  11. Asymmetric Inheritance of Mother Versus Daughter Centrosome in Stem Cell Division

    OpenAIRE

    Yamashita, Yukiko M.; Anthony P Mahowald; Perlin, Julie R.; Fuller, Margaret T.

    2007-01-01

    Adult stem cells often divide asymmetrically to produce one self-renewed stem cell and one differentiating cell, thus maintaining both populations. The asymmetric outcome of stem cell divisions can be specified by an oriented spindle and local self-renewal signals from the stem cell niche. Here we show that developmentally programmed asymmetric behavior and inheritance of mother and daughter centrosomes underlies the stereotyped spindle orientation and asymmetric outcome of stem cell division...

  12. 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.

  13. 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.

  14. 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.

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

    International Nuclear Information System (INIS)

    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

  16. Is the cell division cycle gated by a circadian clock? The case of Chlamydomonas reinhardtii

    OpenAIRE

    1995-01-01

    Circadian oscillators are known to regulate the timing of cell division in many organisms. In the case of Chlamydomonas reinhardtii, however, this conclusion has been challenged by several investigators. We have reexamined this issue and find that the division behavior of Chlamydomonas meets all the criteria for circadian rhythmicity: persistence of a cell division rhythm (a) with a period of approximately 24 h under free-running conditions, (b) that is temperature compensated, and (c) which ...

  17. Nanomolar pyrophosphate detection and nucleus staining in living cells with simple terpyridine–Zn(II) complexes

    OpenAIRE

    Duobin Chao; Shitan Ni

    2016-01-01

    Great efforts have been made to develop fluorescent probes for pyrophosphate (PPi) detection. Nucleus staining with fluorescence microscopy has been also widely investigated. But fluorescent probes for PPi detection with high sensitivity in water medium and nucleus staining with low–cost non–precious metal complexes in living cells are still challenging. Herein, we report simple terpyridine–Zn(II) complexes for selective nanomolar PPi detection over ATP and ADP in water based on aggregation i...

  18. Segrosome Complex Formation during DNA Trafficking in Bacterial Cell Division.

    Science.gov (United States)

    Oliva, María A

    2016-01-01

    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 specialized 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. PMID:27668216

  19. 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.

  20. Specific polar subpopulations of astral microtubules control spindle orientation and symmetric neural stem cell division.

    Science.gov (United States)

    Mora-Bermúdez, Felipe; Matsuzaki, Fumio; Huttner, Wieland B

    2014-01-01

    Mitotic spindle orientation is crucial for symmetric vs asymmetric cell division and depends on astral microtubules. Here, we show that distinct subpopulations of astral microtubules exist, which have differential functions in regulating spindle orientation and division symmetry. Specifically, in polarized stem cells of developing mouse neocortex, astral microtubules reaching the apical and basal cell cortex, but not those reaching the central cell cortex, are more abundant in symmetrically than asymmetrically dividing cells and reduce spindle orientation variability. This promotes symmetric divisions by maintaining an apico-basal cleavage plane. The greater abundance of apical/basal astrals depends on a higher concentration, at the basal cell cortex, of LGN, a known spindle-cell cortex linker. Furthermore, newly developed specific microtubule perturbations that selectively decrease apical/basal astrals recapitulate the symmetric-to-asymmetric division switch and suffice to increase neurogenesis in vivo. Thus, our study identifies a novel link between cell polarity, astral microtubules, and spindle orientation in morphogenesis. PMID:24996848

  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. The equatorial position of the metaphase plate ensures symmetric cell divisions.

    Science.gov (United States)

    Tan, Chia Huei; Gasic, Ivana; Huber-Reggi, Sabina P; Dudka, Damian; Barisic, Marin; Maiato, Helder; Meraldi, Patrick

    2015-01-01

    Chromosome alignment in the middle of the bipolar spindle is a hallmark of metazoan cell divisions. When we offset the metaphase plate position by creating an asymmetric centriole distribution on each pole, we find that metaphase plates relocate to the middle of the spindle before anaphase. The spindle assembly checkpoint enables this centering mechanism by providing cells enough time to correct metaphase plate position. The checkpoint responds to unstable kinetochore-microtubule attachments resulting from an imbalance in microtubule stability between the two half-spindles in cells with an asymmetric centriole distribution. Inactivation of the checkpoint prior to metaphase plate centering leads to asymmetric cell divisions and daughter cells of unequal size; in contrast, if the checkpoint is inactivated after the metaphase plate has centered its position, symmetric cell divisions ensue. This indicates that the equatorial position of the metaphase plate is essential for symmetric cell divisions. PMID:26188083

  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. 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.

  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. Heat-induced alterations in the cell nucleus

    International Nuclear Information System (INIS)

    Hyperthermia may kill eukaryotic cells and may also enhance the radiosensitivity of those cells that survive the heat treatment. Clinically, the possible use of hyperthermia as an adjuvant in the radiotherapeutic treatment of cancer needs the understanding of mechanisms that underlay heat-induced cell death and radiosensitization. By in vitro heating of established human (HeLaS3) and rodent (Ehrlich Ascites Tumor and LM fibroblast) cell lines, both killing and radiosensitization were investigated. (author). 1067 refs.; 76 figs.; 19 tabs

  7. 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.

  8. Effect of vertebroplasty filler materials on viability and gene expression of human nucleus pulposus cells.

    Science.gov (United States)

    Lazáry, Aron; Speer, Gábor; Varga, Péter Pál; Balla, Bernadett; Bácsi, Krisztián; Kósa, János P; Nagy, Zsolt; Takács, István; Lakatos, Péter

    2008-05-01

    Consequences of intradiscal cement leakage--often occurring after vertebral cement augmentation for the treatment of vertebral compression fractures--are still unknown. In this study, we have investigated the influences of vertebroplasty filler materials (polymethylmethacrylate-, calcium phosphate- and calcium sulfate-based bone cement) on isolated nucleus pulposus cells. Cell viability of cultured human nucleus pulposus cells were measured after treatment with vertebroplasty filler materials. Gene expression profile of selected genes was determined with quantitative real-time PCR. The widely used polymethylmethacrylate and calcium phosphate cement significantly decreased cell number in a dose- and time-dependent manner while calcium sulfate cement affected cell viability less. Expression of genes involved in matrix metabolism of nucleus pulposus--aggrecan, collagens, small proteoglycans--as well as important transcription factors have also significantly changed due to treatment (e.g., 2.5-fold decrease in aggrecan expression was determined in cultures due to polymethylmethacrylate treatment). Our results suggest that vertebroplasty filler materials--depending on the type of applied material--can accelerate the degeneration of nucleus pulposus cells resulting in a less flexible disc in case of intradiscal cement leakage. This process may increase the risk of a subsequent new vertebral fracture, the main complication of vertebral augmentation. PMID:18176942

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. Nanomolar pyrophosphate detection and nucleus staining in living cells with simple terpyridine–Zn(II) complexes

    Science.gov (United States)

    Chao, Duobin; Ni, Shitan

    2016-05-01

    Great efforts have been made to develop fluorescent probes for pyrophosphate (PPi) detection. Nucleus staining with fluorescence microscopy has been also widely investigated. But fluorescent probes for PPi detection with high sensitivity in water medium and nucleus staining with low–cost non–precious metal complexes in living cells are still challenging. Herein, we report simple terpyridine–Zn(II) complexes for selective nanomolar PPi detection over ATP and ADP in water based on aggregation induced emission (AIE) and intramolecular charge transfer (ICT). In addition, these terpyridine–Zn(II) complexes were successfully employed for nucleus staining in living cells. These results demonstrated simply obtained terpyridine–Zn(II) complexes are powerful tool for PPi detection and the development of PPi–related studies.

  14. Nanomolar pyrophosphate detection and nucleus staining in living cells with simple terpyridine-Zn(II) complexes.

    Science.gov (United States)

    Chao, Duobin; Ni, Shitan

    2016-01-01

    Great efforts have been made to develop fluorescent probes for pyrophosphate (PPi) detection. Nucleus staining with fluorescence microscopy has been also widely investigated. But fluorescent probes for PPi detection with high sensitivity in water medium and nucleus staining with low-cost non-precious metal complexes in living cells are still challenging. Herein, we report simple terpyridine-Zn(II) complexes for selective nanomolar PPi detection over ATP and ADP in water based on aggregation induced emission (AIE) and intramolecular charge transfer (ICT). In addition, these terpyridine-Zn(II) complexes were successfully employed for nucleus staining in living cells. These results demonstrated simply obtained terpyridine-Zn(II) complexes are powerful tool for PPi detection and the development of PPi-related studies. PMID:27198968

  15. 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

  16. 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.

  17. Computational prediction of strain-dependent diffusion of transcription factors through the cell nucleus.

    Science.gov (United States)

    Nava, Michele M; Fedele, Roberto; Raimondi, Manuela T

    2016-08-01

    Nuclear spreading plays a crucial role in stem cell fate determination. In previous works, we reported evidence of multipotency maintenance for mesenchymal stromal cells cultured on three-dimensional engineered niche substrates, fabricated via two-photon laser polymerization. We correlated maintenance of multipotency to a more roundish morphology of these cells with respect to those cultured on conventional flat substrates. To interpret these findings, here we present a multiphysics model coupling nuclear strains induced by cell adhesion to passive diffusion across the cell nucleus. Fully three-dimensional reconstructions of cultured cells were developed on the basis of confocal images: in particular, the level of nuclear spreading resulted significantly dependent on the cell localization within the niche architecture. We assumed that the cell diffusivity varies as a function of the local volumetric strain. The model predictions indicate that the higher the level of spreading of the cell, the higher the flux across the nucleus of small solutes such as transcription factors. Our results point toward nuclear spreading as a primary mechanism by which the stem cell translates its shape into a fate decision, i.e., by amplifying the diffusive flow of transcriptional activators into the nucleus. PMID:26476736

  18. 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

    2016-01-01

    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. PMID:27436908

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  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. 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...

  6. How-to-Do-It: Hands-on Activities that Relate Mendelian Genetics to Cell Division.

    Science.gov (United States)

    McKean, Heather R.; Gibson, Linda S.

    1989-01-01

    Presented is an activity designed to connect Mendelian laws with the physical processes of cell division. Included are materials production, procedures and worksheets for the meiosis-mitosis game and a genetics game. (CW)

  7. 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.

  8. 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.

  9. Monodisperse Magnetite Nanoparticles Coupled with Nuclear Localization Signal Peptide for Cell-Nucleus Targeting

    OpenAIRE

    Xu, Chenjie; Xie, Jin; Kohler, Nathan; Walsh, Edward G; Chin, Y. Eugene; Sun, Shouheng

    2008-01-01

    Functionalization of monodisperse superparamagnetic magnetite (Fe3O4) nanoparticles for cell specific targeting is crucial for cancer diagnostics and therapeutics. Targeted magnetic nanoparticles can be used to enhance the tissue contrast in magnetic resonance imaging (MRI), to improve the efficiency in anticancer drug delivery, and to eliminate tumor cells by magnetic fluid hyperthermia. Herein we report the nucleus-targeting Fe3O4 nanoparticles functionalized with protein and nuclear locali...

  10. 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.

  11. Tumor-initiating label-retaining cancer cells in human gastrointestinal cancers undergo asymmetric cell division.

    Science.gov (United States)

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

    2012-04-01

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

  12. 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.

  13. 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.

  14. Monodisperse magnetite nanoparticles coupled with nuclear localization signal peptide for cell-nucleus targeting.

    Science.gov (United States)

    Xu, Chenjie; Xie, Jin; Kohler, Nathan; Walsh, Edward G; Chin, Y Eugene; Sun, Shouheng

    2008-03-01

    Functionalization of monodisperse superparamagnetic magnetite (Fe(3)O(4)) nanoparticles for cell specific targeting is crucial for cancer diagnostics and therapeutics. Targeted magnetic nanoparticles can be used to enhance the tissue contrast in magnetic resonance imaging (MRI), to improve the efficiency in anticancer drug delivery, and to eliminate tumor cells by magnetic fluid hyperthermia. Herein we report the nucleus-targeting Fe(3)O(4) nanoparticles functionalized with protein and nuclear localization signal (NLS) peptide. These NLS-coated nanoparticles were introduced into the HeLa cell cytoplasm and nucleus, where the particles were monodispersed and non-aggregated. The success of labeling was examined and identified by fluorescence microscopy and MRI. The work demonstrates that monodisperse magnetic nanoparticles can be readily functionalized and stabilized for potential diagnostic and therapeutic applications. PMID:18080259

  15. 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.

  16. 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.

  17. Study of the mechanism of diatom cell division by means of 29Si isotope tracing

    International Nuclear Information System (INIS)

    Diatoms are delicate unicellular organisms enclosed in a silica frustule, that is made up of two valves. Multiplication of the diatoms occurs by ordinary mitotic cell division. During cell division each cell produces two daughter cells, each of them keeping one of the two valves of the mother cell and producing a new valve by absorbing the silicon present in the environment. The NanoSIMS 50 allows ion imaging to be performed on diatoms in order to determine the site of fixation of silicon. The aim of this study was to observe and compare the mechanism of the construction of the new valve after cell division. To this end, different types of diatoms have been transferred in a culture medium enriched with 29Si and after several days, the distribution of the different isotopes of silicon has been determined by NanoSIMS50 imaging. The construction of new valves has been observed and the isotopic ratio has been determined

  18. 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.

  19. 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.

  20. Direct projection from the suprachiasmatic nucleus to hypophysiotrophic corticotropin-releasing factor immunoreactive cells in the paraventricular nucleus of the hypothalamus demonstrated...

    DEFF Research Database (Denmark)

    Vrang, N.; Larsen, P.J.; Mikkelsen, J.D.

    1995-01-01

    Suprachiasmatic nucleus, paraventricular nucleus, circadian rhythms, phaseolus vulgaris-leucoagglutinin, corticotropin-releasing factor, dual immunocytochemistry......Suprachiasmatic nucleus, paraventricular nucleus, circadian rhythms, phaseolus vulgaris-leucoagglutinin, corticotropin-releasing factor, dual immunocytochemistry...

  1. System X supercomputer provides super tool for simulation of cell division

    OpenAIRE

    Trulove, Susan

    2007-01-01

    Virginia Tech researchers in computer science and biology have used the university's supercomputer, System X, to create models and algorithms that make it possible to simulate the cell cycle -- the processes leading to cell division. They have demonstrated that the new mathematical models and numerical algorithms provide powerful tools for studying the complex processes going on inside living cells.

  2. 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.

  3. Interaction of hyperthermia and radiation on the induction of division delay in Chinese hamster ovary cells

    International Nuclear Information System (INIS)

    The mitotic selection procedure for cell cycle analysis was used in the investigation of the interaction of hyperthermia and ionizing radiation on the induction and duration of division delay in Chinese hamster ovary cells. Hyperthermia (immersion in a 45 degrees C water bath) produced a blockade of cell cycle progression with a transition point in late G2-early M, approximately at the X-ray transition point (35 min prior to selection). The duration of division delay for heated cells depended on the time of immersion: 24 minutes/minute at 45 degrees C. Radiation-induced division delay occurred at a rate of 45 minutes/gray of X-irradiation. When hyperthermic exposure and X-irradiation were combined with less than 1 minute between treatments, a division delay resulted that was approximately the sum of the delays produced by the individual treatments. As the interval between treatments was increased, the overall division delay also increased beyond that which could be accounted for solely by the postponement of the second treatment. These results indicate that hyperthermia and radiation induce division delay by different mechanisms

  4. 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

  5. Cell division patterns and chromosomal segregation defects in oral cancer stem cells.

    Science.gov (United States)

    Kaseb, Hatem O; Lewis, Dale W; Saunders, William S; Gollin, Susanne M

    2016-09-01

    Oral squamous cell carcinoma (OSCC) is a serious public health problem caused primarily by smoking and alcohol consumption or human papillomavirus. The cancer stem cell (CSC) theory posits that CSCs show unique characteristics, including self-renewal and therapeutic resistance. Examining biomarkers and other features of CSCs is critical to better understanding their biology. To this end, the results show that cellular SOX2 immunostaining correlates with other CSC biomarkers in OSCC cell lines and marks the rare CSC population. To assess whether CSC division patterns are symmetrical, resulting in two CSC, or asymmetrical, leading to one CSC and one cancer cell, cell size and fluorescence intensity of mitotic cells stained with SOX2 were analyzed. Asymmetrical SOX2 distribution in ≈25% of the mitoses analyzed was detected. Chromosomal instability, some of which is caused by chromosome segregation defects (CSDs), is a feature of cancer cells that leads to altered gene copy numbers. We compare chromosomal instability (as measured by CSDs) between CSCs (SOX2+) and non-CSCs (SOX2-) from the same OSCC cell lines. CSDs were more common in non-CSCs (SOX2-) than CSCs (SOX2+) and in symmetrical CSC (SOX2+) mitotic pairs than asymmetrical CSC (SOX2+/SOX2-) mitotic pairs. CSCs showed fewer and different types of CSDs after ionizing radiation treatment than non-CSCs. Overall, these data are the first to demonstrate both symmetrical and asymmetrical cell divisions with CSDs in OSCC CSC. Further, the results suggest that CSCs may undergo altered behavior, including therapeutic resistance as a result of chromosomal instability due to chromosome segregation defects. © 2016 Wiley Periodicals, Inc. PMID:27123539

  6. Temperature gradient stimulation for cell division in C. Elegans Embryos on chip

    OpenAIRE

    Baranek, Sophie; Bezler, Alexandra; Adamczyk, Christian; Gönczy, Pierre; Renaud, Philippe

    2010-01-01

    This paper reports on a new microfluidic device for temperature stimulation of cell in in-vitro culture. Micro-electrodes in a meander shape are embedded into the microfluidic channels to generate either a temperature gradient through the culture chamber or a local heat spot under specific cells. One promising application is the control of cell di- vision rate. Here we present first results of the synchronization of cell division in a two-cell stage embryos of C. Elegans.

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

    International Nuclear Information System (INIS)

    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.

  8. 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.

  9. Protective effect of cannabidiol on hydrogen peroxide‑induced apoptosis, inflammation and oxidative stress in nucleus pulposus cells.

    Science.gov (United States)

    Chen, Jie; Hou, Chen; Chen, Xin; Wang, Dong; Yang, Pinglin; He, Xijing; Zhou, Jinsong; Li, Haopeng

    2016-09-01

    Cannabidiol, a major component of marijuana, protects nerves, and exerts antispasmodic, anti-inflammatory and anti‑anxiety effects. In the current study, the protective effect of cannabidiol was observed to prevent hydrogen peroxide (H2O2)‑induced apoptosis, inflammation and oxidative stress in nucleus pulposus cells. Nucleus pulposus cells were isolated from rats and cultured in vitro, and H2O2 was used to construct the nucleus pulposus cell model. Cell viability of the nucleus pulposus cells was assessed using a 3‑(4,5-dimethylthiazol-2-yl)-2,5‑diphenyltetrazolium bromide assay. The ratio of apoptotic cells, and caspase‑3 or cyclooxygenase‑2 (COX‑2) mRNA expression was analyzed by annexin V‑fluorescein isothiocyanate/propidium‑iodide staining and reverse transcription‑quantitative polymerase chain reaction, respectively. The quantities of interleukin (IL)‑1β and interleukin‑6 were measured using a series of assay kits. B-cell lymphoma 2 (Bcl‑2) and inducible nitric oxide synthase (iNOS) protein expression levels were analyzed using western blotting. The present study identified that cannabidiol enhanced cell viability and reduced apoptosis in H2O2‑treated nucleus pulposus cells in vitro using a lumbar disc herniation (LDH) model. In addition, cannabidiol reduced caspase‑3 gene expression and augmented the Bcl‑2 protein expression levels in the nucleus pulposus cells following H2O2 exposure. Pre‑treatment with cannabidiol suppressed the promotion of COX‑2, iNOS, IL‑1β and IL‑6 expression in the nucleus pulposus cells following H2O2 exposure. Taken together, these results suggest that cannabidiol potentially exerts its protective effect on LDH via the suppression of anti‑apoptosis, anti‑inflammation and anti‑oxidative activities in nucleus pulposus cells. PMID:27430346

  10. Expression of the wild-type p53 antioncogene induces guanine nucleotide-dependent stem cell division kinetics.

    OpenAIRE

    Sherley, J L; Stadler, P B; Johnson, D. R.

    1995-01-01

    The predominant type of cell division in adult mammals is renewal growth. Renewing stem cells in somatic tissues undergo continuous asymmetric divisions. One new daughter cell retains the division potential of the original stem cell, while the other differentiates into a functional constituent of the tissue. Disruptions of this process lead to the development of human cancers. We show that through a guanine nucleotide-dependent mechanism, the p53 antioncogene can induce exponentially dividing...

  11. Phosphorus deficiency inhibits cell division but not growth in the dinoflagellate Amphidinium carterae

    Directory of Open Access Journals (Sweden)

    Meizhen eLi

    2016-06-01

    Full Text Available Phosphorus (P is an essential nutrient element for the growth of phytoplankton. How P deficiency affects population growth and the cell division cycle in dinoflagellates has only been studied in some species, and how it affects photosynthesis and cell growth remains poorly understood. In the present study, we investigated the impact of P deficiency on the cell division cycle, the abundance of the carbon-fixing enzyme Rubisco, and other cellular characteristics in the Gymnodiniales peridinin-plastid species Amphidinium carterae. We found that under P-replete condition, the cell cycle actively progressed in the culture in a 24-hour diel cycle with daily growth rates markedly higher than the P-deficient cultures, in which cells were arrested in the G1 phase and cell size significantly enlarged. The results suggest that, as in previously studied dinoflagellates, P deficiency likely disenables A. carterae to complete DNA duplication or check-point protein phosphorylation. We further found that under P-deficient condition, overall photosystem II quantum efficiency (Fv/Fm ratio and Rubisco abundance decreased but not significantly, while cellular contents of carbon, nitrogen, and proteins increased significantly. These observations indicated that under P-deficiency, this dinoflagellate was able to continue photosynthesis and carbon fixation, such that proteins and photosynthetically fixed carbon could accumulate resulting in continued cell growth in the absence of division. This is likely an adaptive strategy thereby P-limited cells can be ready to resume the cell division cycle upon resupply of phosphorus.

  12. Symmetric cell division in pseudohyphae of the yeast Saccharomyces cerevisiae.

    OpenAIRE

    Kron, S J; Styles, C. A.; Fink, G R

    1994-01-01

    Laboratory strains of Saccharomyces cerevisiae are dimorphic; in response to nitrogen starvation they switch from a yeast form (YF) to a filamentous pseudohyphal (PH) form. Time-lapse video microscopy of dividing cells reveals that YF and PH cells differ in their cell cycles and budding polarity. The YF cell cycle is controlled at the G1/S transition by the cell-size checkpoint Start. YF cells divide asymmetrically, producing small daughters from full-sized mothers. As a result, mothers and d...

  13. 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

  14. 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

  15. 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

  16. 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

  17. 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

    2010-11-01

    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.

  18. 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 ...

  19. [Kinetics of cell division in peripheral blood lymphocytes of stainless steel welders].

    Science.gov (United States)

    Myślak, M; Kośmider, K

    1997-01-01

    Stainless steel welders are not potential occupational risk of geno- and cytotoxic exposure to chemical mutagens and carcinogens contained in welding fumes. The studies of biological activity of welding fumes evidence their cytotoxicity which depends on chromium and nickel content. In 20 stainless steel welders exposed to chromium and nickel contained in welding fumes, kinetics of cell division was assessed in the culture of peripheral blood lymphocytes. No significant differences were found in the cell division rates between the group of exposed welders and the controls. In welders who smoke, the number of cells present after 70 hrs in the third mitotic division, was reduced in comparison to smokers in the control group what may be considered as a symptom of cytotoxic effect of a combined exposure to welding fumes and tobacco smoke.

  20. Cell division licensing in the multi-chromosomal Vibrio cholerae bacterium.

    Science.gov (United States)

    Galli, Elisa; Poidevin, Mickaël; Le Bars, Romain; Desfontaines, Jean-Michel; Muresan, Leila; Paly, Evelyne; Yamaichi, Yoshiharu; Barre, François-Xavier

    2016-01-01

    Cell division must be coordinated with chromosome replication and segregation to ensure the faithful transmission of genetic information during proliferation. In most bacteria, assembly of the division apparatus, the divisome, starts with the polymerization of a tubulin homologue, FtsZ, into a ring-like structure at mid-cell, the Z-ring(1). It typically occurs at half of the cell cycle when most of the replication and segregation cycle of the unique chromosome they generally harbour is achieved(2). The chromosome itself participates in the regulation of cell division, at least in part because it serves as a scaffold to position FtsZ polymerization antagonists(3). However, about 10% of bacteria have more than one chromosome(4), which raises questions about the way they license cell division(3). For instance, the genome of Vibrio cholerae, the agent of cholera, is divided between a 3 Mbp replicon that originates from the chromosome of its mono-chromosomal ancestor, Chr1, and a 1 Mbp plasmid-derived replicon, Chr2 (ref. 5). Here, we show that Chr2 harbours binding motifs for an inhibitor of Z-ring formation, which helps accurately position the V. cholerae divisome at mid-cell and postpones its assembly to the very end of the cell cycle. PMID:27562255

  1. 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.

  2. 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.

  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. 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.

  5. miR-155 Inhibits Nucleus Pulposus Cells' Degeneration through Targeting ERK 1/2

    Science.gov (United States)

    Dai, Libing; Yao, Yicun; Qin, Shengnan; Xie, Han; Wang, Wen

    2016-01-01

    We first investigated the difference in microRNA expression between normal NP cells and degenerative NP cells using gene chip. We have found that the expression of ERK1/2 was decreased with overexpression of miR-155 in normal nucleus pulposus cell. Expression of ERK1/2 was increased with inhibition of miR-155. Overexpression or inhibition of miR-155 had no effects on the expression level of mRNA ERK1/2 in nucleus pulposus cell, which showed that miR-155 affected the expression of pERK1/2 after transcription of ERK1/2 mRNA indicating that ERK1/2 was a new target protein regulated by miR-155. In the degeneration of intervertebral disc, inhibited miR-155 decreased the expressions of extracellular main matrix collagen II and glycosaminoglycan and increased expression of ERK1/2. Taken together, our data suggested that miR-155 was the identified miRNA which regulated NP cells degenerated through directly targeting ERK1/2. PMID:27635110

  6. 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.

  7. 大鼠纹状体边缘区与杏仁核和终纹床核之间相互联系的免疫组织化学研究%THE CONNECTION AMONG THE MARGINAL DIVISION OF STRIATUM,AMYGDALOID NUCLEUS AND BED NUCLEUS OF THE STRIA TERMINALIS IN THE RAT BRAIN AS REVEALED BY IMMUNOHISTOCHEMISTRY

    Institute of Scientific and Technical Information of China (English)

    李耀宇; 舒斯云; 包新民; 吴文龙

    2000-01-01

    为了解大鼠纹状体内的神经活性物质与边缘系统重要结构杏仁核和终纹床核内相应神经活性物质之间的关系。对大鼠脑的连续冠状切片进行了P物质、降钙素基因相关肽、亮氨酸-脑啡肽、胆囊收缩素和神经元型一氧化氮合酶等的免疫细胞化学反应(ABC法)。结果证明:P物质、降钙素基因相关肽和胆囊收缩素在纹状体中主要分布在边缘区;亮氨酸-脑啡肽主要分布在苍白球,其次分布在边缘区;神经元型一氧化氮合酶则主要分布在尾壳核和边缘区。上述神经活性物质同时也集中分布在杏仁核和终纹床核,而且边缘区内的这些神经活性物质与杏仁核和终纹床核内的相同物质存在着纤维联系。本研究结果说明:边缘区与边缘系统之间存在着神经化学的相互关系,边缘区可能属于边缘系统的一部分。%To understand the relationship of neurotransmitter between the striatum and limbic system such as amygdaloid nucle-us and bed nucleus of the stria terminalis. 30 male Sprague Dawley rats were used. Immunohistochemical ABC method was per-formed to detect the expression of substance P (SP), calcitonin gene-related peptide (CGRP), leucine-enkephalin (L-enk),cholecyctokinin (CCK) and neuronal nitric oxide synthase (NOS) on seetions of the brain. Some transmitters including substanceP, calcitonin gene-related peptide and cholecyctokinin were mainly distributed at the marginal division of the striatum. Theleucine-enkephalin was mainly distributed at the globus pallidus and was secondly distributed at the marginal division of the stria-tun. The neuronal nitric oxide synthase was mainly distributed at caudate putamen and the marginal division. All these transmit-ters were not only distributed at amygdaloid nucleus and bed nucleus of the stria terminalis, but also had fibers connection amongthe amygdaloid nucleus, marginal division and bed nucleus of the stria terminalis

  8. Escherichia coli cell division protein FtsZ is a guanine nucleotide binding protein.

    OpenAIRE

    Mukherjee, A; Dai, K; Lutkenhaus, J

    1993-01-01

    FtsZ is an essential cell division protein in Escherichia coli that forms a ring structure at the division site under cell cycle control. The dynamic nature of the FtsZ ring suggests possible similarities to eukaryotic filament forming proteins such as tubulin. In this study we have determined that FtsZ is a GTP/GDP binding protein with GTPase activity. A short segment of FtsZ is homologous to a segment in tubulin believed to be involved in the interaction between tubulin and guanine nucleoti...

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. Gibberellin reactivates and maintains ovary-wall cell division causing fruit set in parthenocarpic Citrus species.

    Science.gov (United States)

    Mesejo, Carlos; Yuste, Roberto; Reig, Carmina; Martínez-Fuentes, Amparo; Iglesias, Domingo J; Muñoz-Fambuena, Natalia; Bermejo, Almudena; Germanà, M Antonietta; Primo-Millo, Eduardo; Agustí, Manuel

    2016-06-01

    Citrus is a wide genus in which most of the cultivated species and cultivars are natural parthenocarpic mutants or hybrids (i.e. orange, mandarin, tangerine, grapefruit). The autonomous increase in GA1 ovary concentration during anthesis was suggested as being the stimulus responsible for parthenocarpy in Citrus regardless of the species. To determine the exact GA-role in parthenocarpic fruit set, the following hypothesis was tested: GA triggers and maintains cell division in ovary walls causing fruit set. Obligate and facultative parthenocarpic Citrus species were used as a model system because obligate parthenocarpic Citrus sp (i.e. Citrus unshiu) have higher GA levels and better natural parthenocarpic fruit set compared to other facultative parthenocarpic Citrus (i.e. Citrus clementina). The autonomous activation of GA synthesis in C. unshiu ovary preceded cell division and CYCA1.1 up-regulation (a G2-stage cell cycle regulator) at anthesis setting a high proportion of fruits, whereas C. clementina lacked this GA-biosynthesis and CYCA1.1 up-regulation failing in fruit set. In situ hybridization experiments revealed a tissue-specific expression of GA20ox2 only in the dividing tissues of the pericarp. Furthermore, CYCA1.1 expression correlated endogenous GA1 content with GA3 treatment, which stimulated cell division and ovary growth, mostly in C. clementina. Instead, paclobutrazol (GA biosynthesis inhibitor) negated cell division and reduced fruit set. Results suggest that in parthenocarpic citrus the specific GA synthesis in the ovary walls at anthesis triggers cell division and, thus, the necessary ovary growth rate to set fruit. PMID:27095396

  19. Do Online Labs Work? An Assessment of an Online Lab on Cell Division

    Science.gov (United States)

    Gilman, Sharon L.

    2006-01-01

    Some studies show students successfully learning science through online courses. This study compared students doing an online and in-class lab exercise on cell division. Online students performed slightly but significantly better on a follow-up content quiz, however, about half those expressed a strong preference for in-class lab work.

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

    Science.gov (United States)

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

    2012-01-01

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

  1. The formation of argpyrimidine, a methylglyoxal-arginine adduct, in the nucleus of neural cells

    International Nuclear Information System (INIS)

    Methylglyoxal (MG) is an endogenous metabolite in glycolysis and forms stable adducts primarily with arginine residues of intracellular proteins. The biological role of this modification in cell function is not known. In the present study, we found that a MG-detoxification enzyme glyoxalase I (GLO1) is mainly expressed in the ventricular zone (VZ) at embryonic day 16 which neural stem and progenitor cells localize. Moreover, immunohistochemical analysis revealed that argpyrimidine, a major MG-arginine adduct, is predominantly produced in cortical plate neurons not VZ during cerebral cortex development and is exclusively located in the nucleus. Immunoblotting experiment showed that the formation of argpyrimidine occurs on some nuclear proteins of cortical neurons. To our knowledge, this is first report of the argpyrimidine formation in the nucleus of neuron. These findings suggest that GLO1, which is dominantly expressed in the embryonic VZ, reduces the intracellular level of MG and suppresses the formation of argpyrimidine in neural stem and progenitor cells. Argpyrimidine may contribute to the neural differentiation and/or the maintenance of the differentiated state via the modification of nuclear proteins.

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

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

    International Nuclear Information System (INIS)

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

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

    OpenAIRE

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

    2015-01-01

    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 ep...

  10. 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.

  11. DNA synthesis and cell division in the adult primate brain

    International Nuclear Information System (INIS)

    It is generally accepted that the adult human brain is incapable of producing new neuron. Even cursory examination of neurologic, neuropathologic, or neurobiological textbooks published during the past 50 years will testify that this belief is deeply entrenched. In his classification of cell populations on the basis of their proliferative behavior, Leblond regarded neurons of the central nervous system as belonging to a category of static, nonrenewing epithelial tissue incapable of expanding or replenishing itself. This belief, however needs to re reexamined for two major reasons: First, as reviewed below, a number of reports have provided evidence of neurogenesis in adult brain of several vertebrate species. Second, the capacity for neurogenesis in the adult primate central nervous system has never been examined by modern methods. In this article the author described recent results from an extensive autoradiographic analysis performed on twelve rhesus monkeys injected with the specific DNA precursor [3H] thymidine at ages ranging from 6 postnatal months to 17 years

  12. Characterisation of cell death inducing Phytophthora capsici CRN effectors suggests diverse activities in the host nucleus

    Directory of Open Access Journals (Sweden)

    Remco eStam

    2013-10-01

    Full Text Available Plant-Microbe interactions are complex associations that feature recognition of Pathogen Associated Molecular Patterns by the plant immune system and dampening of subsequent responses by pathogen encoded secreted effectors. With large effector repertoires now identified in a range of sequenced microbial genomes, much attention centres on understanding their roles in immunity or disease. These studies not only allow identification of pathogen virulence factors and strategies, they also provide an important molecular toolset suited for studying immunity in plants. The Phytophthora intracellular effector repertoire encodes a large class of proteins that translocate into host cells and exclusively target the host nucleus. Recent functional studies have implicated the CRN protein family as an important class of diverse effectors that target distinct subnuclear compartments and modify host cell signalling. Here, we characterised three necrosis inducing CRNs and show that there are differences in the levels of cell death. We show that only expression of CRN20_624 has an additive effect on PAMP induced cell death but not AVR3a induced ETI. Given their distinctive phenotypes, we assessed localisation of each CRN with a set of nuclear markers and found clear differences in CRN subnuclear distribution patterns. These assays also revealed that expression of CRN83_152 leads to a distinct change in nuclear chromatin organisation, suggesting a distinct series of events that leads to cell death upon over-expression. Taken together, our results suggest diverse functions carried by CRN C-termini, which can be exploited to identify novel processes that take place in the host nucleus and are required for immunity or susceptibility.

  13. Cell segmentation for division rate estimation in computerized video time-lapse microscopy

    Science.gov (United States)

    He, Weijun; Wang, Xiaoxu; Metaxas, Dimitris; Mathew, Robin; White, Eileen

    2007-02-01

    The automated estimation of cell division rate plays an important role in the evaluation of a gene function in high throughput biomedical research. Using Computerized Video Time-Lapse (CVTL) microcopy , it is possible to follow a large number of cells in their physiological conditions for several generations. However analysis of this large volume data is complicated due to cell to cell contacts in a high density population. We approach this problem by segmenting out cells or cell clusters through a learning method. The feature of a pixel is represented by the intensity and gradient information in a small surrounding sub-window. Curve evolution techniques are used to accurately find the cell or cell cluster boundary. With the assumption that the average cell size is the same in each frame, we can use the cell area to estimate the cell division rate. Our segmentation results are compared to manually-defined ground truth. Both recall and precision measures for segmentation accuracy are above 95%.

  14. ABCG2 Localizes to the Nucleus and Modulates CDH1 Expression in Lung Cancer Cells

    Directory of Open Access Journals (Sweden)

    Shu-Ching Liang

    2015-03-01

    Full Text Available Breast cancer resistance protein [BCRP/ATP-binding cassette subfamily G member 2 (ABCG2] is a member of the ATP-binding cassette transporter family. The presence of ABCG2 on the plasma membrane in many kinds of human cancer cells contributes to multidrug resistance during chemotherapy, and it has been used as the side population marker for identifying cancer stem cells in lung cancers. We report here that, in addition to the membranous form, ABCG2 proteins are also found inside the nucleus, where they bind to the E-box of CDH1 (E-cadherin promoter and regulate transcription of this gene. Increased expression of ABCG2 causes an increase of E-cadherin and attenuates cell migration, whereas knockdown of ABCG2 downregulates E-cadherin and enhances cell motility. In mice, xenografted A549 cells that have less ABCG2 are more likely to metastasize from the subcutaneous inoculation site to the internal organs. However, for the cancer cells that have already entered the blood circulation, an increased level of ABCG2, and correspondingly increased E-cadherin, may facilitate circulating cancer cells to colonize at a distant site and form a metastatic tumor. We propose a novel role for nuclear ABCG2 that functions as a transcription regulator and participates in modulation of cancer metastasis.

  15. Asymmetric division triggers cell-specific gene expression through coupled capture and stabilization of a phosphatase

    OpenAIRE

    Bradshaw, Niels; Losick, Richard

    2015-01-01

    Formation of a division septum near a randomly chosen pole during sporulation in Bacillus subtilis creates unequal sized daughter cells with dissimilar programs of gene expression. An unanswered question is how polar septation activates a transcription factor (σF) selectively in the small cell. We present evidence that the upstream regulator of σF, the phosphatase SpoIIE, is compartmentalized in the small cell by transfer from the polar septum to the adjacent cell pole where SpoIIE is protect...

  16. 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.

  17. 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

  18. 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.

  19. 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. PMID:27053678

  20. 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.

  1. Neurons and Glial Cells Are Added to the Female Rat Anteroventral Periventricular Nucleus During Puberty.

    Science.gov (United States)

    Mohr, Margaret A; Garcia, Francisca L; DonCarlos, Lydia L; Sisk, Cheryl L

    2016-06-01

    The anteroventral periventricular nucleus (AVPV) orchestrates the neuroendocrine-positive feedback response that triggers ovulation in female rodents. The AVPV is larger and more cell-dense in females than in males, and during puberty, only females develop the capacity to show a positive feedback response. We previously reported a potential new mechanism to explain this female-specific gain of function during puberty, namely a female-biased sex difference in the pubertal addition of new cells to the rat AVPV. Here we first asked whether this sex difference is due to greater cell proliferation and/or survival in females. Female and male rats received the cell birthdate marker 5-bromo-2'-deoxyuridine (BrdU; 200 mg/kg, ip) on postnatal day (P) 30; brains were collected at short and long intervals after BrdU administration to assess cell proliferation and survival, respectively. Overall, females had more BrdU-immunoreactive cells in the AVPV than did males, with no sex differences in the rate of cell attrition over time. Thus, the sex difference in pubertal addition of AVPV cells appears to be due to greater cell proliferation in females. Next, to determine the phenotype of pubertally born AVPV cells, daily BrdU injections were given to female rats on P28-56, and tissue was collected on P77 to assess colocalization of BrdU and markers for mature neurons or glia. Of the pubertally born AVPV cells, approximately 15% differentiated into neurons, approximately 19% into astrocytes, and approximately 23% into microglia. Thus, both neuro- and gliogenesis occur in the pubertal female rat AVPV and potentially contribute to maturation of female reproductive function. PMID:27145006

  2. 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.

  3. Localization of Cell Division Protein FtsQ by Immunofluorescence Microscopy in Dividing and Nondividing Cells of Escherichia coli

    Science.gov (United States)

    Buddelmeijer, Nienke; Aarsman, Mirjam E. G.; Kolk, Arend H. J.; Vicente, Miguel; Nanninga, Nanne

    1998-01-01

    The localization of cell division protein FtsQ in Escherichia coli wild-type cells was studied by immunofluorescence microscopy with specific monoclonal antibodies. FtsQ could be localized to the division site in constricting cells. FtsQ could also localize to the division site in ftsQ1(Ts) cells grown at the permissive temperature. A hybrid protein in which the cytoplasmic domain and the transmembrane domain were derived from the γ form of penicillin-binding protein 1B and the periplasmic domain was derived from FtsQ was also able to localize to the division site. This result indicates that the periplasmic domain of FtsQ determines the localization of FtsQ, as has also been concluded by others for the periplasmic domain of FtsN. Noncentral FtsQ foci were found in the area of the cell where the nucleoid resides and were therefore assumed to represent sites where the FtsQ protein is synthesized and simultaneously inserted into the cytoplasmic membrane. PMID:9829918

  4. 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...

  5. 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.

  6. Mapping and morphometric analysis of synapses and spines on fusiform cells in the dorsal cochlear nucleus.

    Science.gov (United States)

    Salloum, Rony H; Chen, Guoyou; Velet, Liliya; Manzoor, Nauman F; Elkin, Rachel; Kidd, Grahame J; Coughlin, John; Yurosko, Christopher; Bou-Anak, Stephanie; Azadi, Shirin; Gohlsch, Stephanie; Schneider, Harold; Kaltenbach, James A

    2014-01-01

    Fusiform cells are the main integrative units of the mammalian dorsal cochlear nucleus (DCN), collecting and processing inputs from auditory and other sources before transmitting information to higher levels of the auditory system. Despite much previous work describing these cells and the sources and pharmacological identity of their synaptic inputs, information on the three-dimensional organization and utltrastructure of synapses on these cells is currently very limited. This information is essential since an understanding of synaptic plasticity and remodeling and pathologies underlying disease states and hearing disorders must begin with knowledge of the normal characteristics of synapses on these cells, particularly those features that determine the strength of their influence on the various compartments of the cell. Here, we employed serial block face scanning electron microscopy (SBFSEM) followed by 3D reconstructions to map and quantitatively characterize synaptic features on DCN fusiform cells. Our results reveal a relative sparseness of synapses on the somata of fusiform cells but a dense distribution of synapses on apical and basal dendrites. Synapses on apical dendrites were smaller and more numerous than on basal dendrites. The vast majority of axosomatic terminals were found to be linked to other terminals connected by the same axon or different branches of the same axon, suggesting a high degree of divergent input to fusiform cells. The size of terminals was correlated with the number of mitochondria and with the number of active zones, which was highly correlated with the number of postsynaptic densities, suggesting that larger terminals exert more powerful influence on the cell than smaller terminals. These size differences suggest that the input to basal dendrites, most likely those from the auditory nerve, provide the most powerful sources of input to fusiform cells, while those to apical dendrites (e.g., parallel fiber) are weaker but more

  7. Mapping and Morphometric Analysis of Synapses and Spines on Fusiform Cells in the Dorsal Cochlear Nucleus.

    Directory of Open Access Journals (Sweden)

    Rony H. Salloum

    2014-09-01

    Full Text Available Fusiform cells are the main integrative units of the mammalian dorsal cochlear nucleus (DCN, collecting and processing inputs from auditory and other sources before transmitting information to higher levels of the auditory system. Despite much previous work describing these cells and the sources and pharmacological identity of their synaptic inputs, information on the 3- dimensional organization and utltrastructure of synapses on these cells is currently very limited. This information is essential since an understanding of synaptic plasticity and remodeling and pathologies underlying disease states and hearing disorders must begin with knowledge of the normal characteristics of synapses on these cells, particularly those features that determine the strength of their influence on the various compartments of the cell. Here, we employed serial block face scanning electron microscopy (SBFSEM followed by 3D reconstructions to map and quantitatively characterize synaptic features on DCN fusiform cells. Our results reveal a relative sparseness of synapses on the somata of fusiform cells but a dense distribution of synapses on apical and basal dendrites. Synapses on apical dendrites were smaller and more numerous than on basal dendrites. The vast majority of axosomatic terminals were found to be linked to other terminals connected by the same axon or different branches of the same axon, suggesting a high degree of divergent input to fusiform cells. The size of terminals was correlated with the number of mitochondria and with the number of active zones, which was highly correlated with the number of postsynaptic densities, suggesting that larger terminals exert more powerful influence on the cell than smaller terminals. These size differences suggest that the input to basal dendrites, most likely those from the auditory nerve, provide the most powerful sources of input to fusiform cells, while those to apical dendrites (e.g., parallel fiber are weaker

  8. Flat leaf formation realized by cell-division control and mutual recessive gene regulation.

    Science.gov (United States)

    Hayakawa, Yoshinori; Tachikawa, Masashi; Mochizuki, Atsushi

    2016-09-01

    Most of the land plants generally have dorsoventrally flat leaves, maximizing the surface area of both upper (adaxial) side and lower (abaxial) side. The former is specialized for light capturing for photosynthesis and the latter is specialized for gas exchange. From findings of molecular genetics, it has been considered that the coupled dynamics between tissue morphogenesis and gene regulation for cell identity is responsible for making flat leaves. The hypothesis claims that a flat leaf is generated under two assumptions, (i) two mutually recessive groups of genes specify adaxial and abaxial sides of a leaf, (ii) cell divisions are induced at the limited region in the leaf margin where both of two groups are expressed. We examined the plausibility and possibility of this hypothesis from the dynamical point of view. We studied a mathematical model where two processes are coupled, tissue morphogenesis induced by cell division and deformation, and dynamics of gene regulations. From the analysis of the model we found that the classically believed hypothesis is not sufficient to generate flat leaves with high probability. We examined several different modifications and revision of the model. Then we found that a simple additional rule of polarized cell division facilitates flat leaf formation. The result of our analysis gives prediction of possible mechanism, which can be easily verified in experiments. PMID:27287339

  9. Cell division interference in newly fertilized ovules induces stenospermocarpy in cross-pollinated citrus fruit.

    Science.gov (United States)

    Mesejo, Carlos; Muñoz-Fambuena, Natalia; Reig, Carmina; Martínez-Fuentes, Amparo; Agustí, Manuel

    2014-08-01

    Seedlessness is a highly desirable characteristic in fresh fruits. However, post-fertilization seed abortion of cross-pollinated citrus fruit is uncommon. The factors regulating stenospermocarpy in citrus are unknown. In this research, we induced stenospermocarpy interfering in newly fertilized ovule cell division. The research also elucidates the most sensitive stage for ovule/seed abortion in citrus. Experiments were conducted with 'Afourer' mandarin that cross-pollinates with several cultivars and species. Cross-pollinated fruitlets were treated with maleic hydrazide (MH), a systemic growth regulator that specifically interferes in cell division. MH reduced ovule growth rate, the number of cell layers in nucella and inhibited embryo sac expansion; moreover, the treatment increased callose accumulation in nucella and surrounding the embryo sac. Fruits developed an early-aborted seed type with an immature, soft and edible seed coat. Seed number (-80%) and seed weight (-46%) were reduced in mature fruits. MH also hampered cell division in ovary walls, mesocarp and endocarp, thus reducing daily fruitlet growth and increasing fruit abscission. Stenospermocarpy could only be induced for a short period of time in the progamic phase of fertilization, specifically, when ovules are ready to be fertilized (7 days after anthesis) to early stages of embryo sac development (14 days after anthesis). PMID:25017163

  10. 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.

  11. EphB4 localises to the nucleus of prostate cancer cells

    International Nuclear Information System (INIS)

    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. 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.

  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. 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.

  16. 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...

  17. Interplay of migratory and division forces as a generic mechanism for stem cell patterns

    Science.gov (United States)

    Hannezo, Edouard; Coucke, Alice; Joanny, Jean-François

    2016-02-01

    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.

  18. 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.

  19. 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.

  20. Niche-associated activation of rac promotes the asymmetric division of Drosophila female germline stem cells.

    Directory of Open Access Journals (Sweden)

    Wen Lu

    Full Text Available BACKGROUND: Drosophila female germline stem cells (GSCs reside adjacent to a cellular niche that secretes Bone Morphogenetic Protein (BMP ligands and anchors the GSCs through adherens junctions. The GSCs divide asymmetrically such that one daughter remains in the niche as a GSC, while the other is born away from the niche and differentiates. However, given that the BMP signal can be diffusible, it remains unclear how a local extracellular asymmetry is sufficient to result in a robust pattern of asymmetric division. METHODS AND FINDINGS: Here we show that GSCs are polarized with respect to the cellular niche. We first use a modified biosensor to demonstrate that the small GTPase Rac is asymmetrically activated within the GSC at the niche-GSC interface. Experiments using loss-of-function and gain-of-function mutations in Rac indicate that asymmetric Rac activity both localizes the microtubule binding protein Apc2 to orient one GSC centrosome at the niche-GSC interface during interphase and activates the Jun N-terminal kinase pathway to increase the ability of the GSC to respond to BMP ligands. Other processes act in concert with each function of Rac. Specifically, we demonstrate that the GSC cell cycle arrests at prometaphase if centrosomes are misoriented. CONCLUSIONS: Thus, the GSCs, an adult stem cell present in a cellular niche, have a niche-associated polarity that couples control of the division plane with increased response to an extracellular maintenance signal. Other processes work in parallel with the Rac-mediated polarity to ensure a robust pattern of asymmetric division. We suggest that all adult stem cells likely employ multiple, independently acting mechanisms to ensure asymmetric division to maintain tissue homeostasis.

  1. ASPM regulates symmetric stem cell division by tuning Cyclin E ubiquitination

    Science.gov (United States)

    Capecchi, Mario R.; Pozner, Amir

    2016-01-01

    We generate a mouse model for the human microcephaly syndrome by mutating the ASPM locus, and demonstrate a premature exhaustion of the neuronal progenitor pool due to dysfunctional self-renewal processes. Earlier studies have linked ASPM mutant progenitor excessive cell cycle exit to a mitotic orientation defect. Here, we demonstrate a mitotic orientation-independent effect of ASPM on cell cycle duration. We pinpoint the cell fate-determining factor to the length of time spent in early G1 before traversing the restriction point. Characterization of the molecular mechanism reveals an interaction between ASPM and the Cdk2/Cyclin E complex, regulating the Cyclin activity by modulating its ubiquitination, phosphorylation and localization into the nucleus, before the cell is fated to transverse the restriction point. Thus, we reveal a novel function of ASPM in mediating the tightly coordinated Ubiquitin- Cyclin E- Retinoblastoma- E2F bistable-signalling pathway controlling restriction point progression and stem cell maintenance. PMID:26581405

  2. 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.

  3. 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

  4. 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.

  5. 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.

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

    International Nuclear Information System (INIS)

    Substances which restore impaired cell division in UV-irradiated E. coli B were surveyed among various bacteria. The active substance was found only in several genera of Gram-negative bacteria, i.e., Escherichia, Enterobacter, Salmonella and some species of Pseudomonas. The activity in the dialyzed cell extract of E. coli B/r was observed in the presence of β-NAD and was enhanced by Mg2+ and Mn2+. The active substance was very labile, but the activity was protected by 1 mM dithiothreitol in the process of purification. The activity of a fraction recovered through DEAE-cellulose column chromatography was stimulated by the presence of membrane fraction. Upon treatment with lipid-degrading enzymes and proteases, the division-stimulating activity was lost or reduced. It appears that the inactivation by lipase and phospholipase A2 was due to the formation of lysophospholipids and that a proteinous substance participated in the recovery of impaired cell division of UV-irradiated E. coli B

  7. Structural and functional studies of MinD ATPase: implications for the molecular recognition of the bacterial cell division apparatus

    OpenAIRE

    Hayashi, Ikuko; Oyama, Takuji; Morikawa, Kosuke

    2001-01-01

    Proper placement of the bacterial cell division site requires the site-specific inactivation of other potential division sites. In Escherichia coli, selection of the correct mid-cell site is mediated by the MinC, MinD and MinE proteins. To clarify the functional role of the bacterial cell division inhibitor MinD, which is a membrane-associated ATPase that works as an activator of MinC, we determined the crystal structure of a Pyrococcus furiosus MinD homologue complexed with a substrate analo...

  8. 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.

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

    NARCIS (Netherlands)

    P. Gamba; E. Rietkötter; R.A. Daniel; L.W. Hamoen

    2015-01-01

    Cell division in bacteria is initiated by the polymerization of FtsZ into a ring-like structure at midcell that functions as a scaffold for the other cell division proteins. In Bacillus subtilis, the conserved cell division protein EzrA is involved in modulation of Z-ring formation and coordination

  10. Agrobacterium tumefaciens and A. rhizogenes use different proteins to transport bacterial DNA into the plant cell nucleus.

    Science.gov (United States)

    Ream, Walt

    2009-07-01

    Agrobacterium tumefaciens and A. rhizogenes transport single-stranded DNA (ssDNA; T-strands) and virulence proteins into plant cells through a type IV secretion system. DNA transfer initiates when VirD2 nicks border sequences in the tumour-inducing plasmid, attaches to the 5' end, and pilots T-strands into plant cells. Agrobacterium tumefaciens translocates ssDNA-binding protein VirE2 into plant cells where it targets T-strands into the nucleus. Some A. rhizogenes strains lack VirE2 but transfer T-strands efficiently due to the GALLS gene, which complements an A. tumefaciens virE2 mutant. VirE2 and full-length GALLS (GALLS-FL) contain nuclear localization sequences that target these proteins to the plant cell nucleus. VirE2 binds cooperatively to T-strands allowing it to move ssDNA without ATP hydrolysis. Unlike VirE2, GALLS-FL contains ATP-binding and helicase motifs similar to those in TraA, a strand transferase involved in conjugation. VirE2 may accumulate in the nucleus and pull T-strands into the nucleus using the force generated by cooperative DNA binding. GALLS-FL accumulates inside the nucleus where its predicted ATP-dependent strand transferase may pull T-strands into the nucleus. These different mechanisms for nuclear import of T-strands may affect the efficiency and quality of transgenic events in plant biotechnology applications. PMID:21255274

  11. Polar flagellar biosynthesis and a regulator of flagellar number influence spatial parameters of cell division in Campylobacter jejuni.

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    Murat Balaban

    2011-12-01

    Full Text Available Spatial and numerical regulation of flagellar biosynthesis results in different flagellation patterns specific for each bacterial species. Campylobacter jejuni produces amphitrichous (bipolar flagella to result in a single flagellum at both poles. These flagella confer swimming motility and a distinctive darting motility necessary for infection of humans to cause diarrheal disease and animals to promote commensalism. In addition to flagellation, symmetrical cell division is spatially regulated so that the divisome forms near the cellular midpoint. We have identified an unprecedented system for spatially regulating cell division in C. jejuni composed by FlhG, a regulator of flagellar number in polar flagellates, and components of amphitrichous flagella. Similar to its role in other polarly-flagellated bacteria, we found that FlhG regulates flagellar biosynthesis to limit poles of C. jejuni to one flagellum. Furthermore, we discovered that FlhG negatively influences the ability of FtsZ to initiate cell division. Through analysis of specific flagellar mutants, we discovered that components of the motor and switch complex of amphitrichous flagella are required with FlhG to specifically inhibit division at poles. Without FlhG or specific motor and switch complex proteins, cell division occurs more often at polar regions to form minicells. Our findings suggest a new understanding for the biological requirement of the amphitrichous flagellation pattern in bacteria that extend beyond motility, virulence, and colonization. We propose that amphitrichous bacteria such as Campylobacter species advantageously exploit placement of flagella at both poles to spatially regulate an FlhG-dependent mechanism to inhibit polar cell division, thereby encouraging symmetrical cell division to generate the greatest number of viable offspring. Furthermore, we found that other polarly-flagellated bacteria produce FlhG proteins that influence cell division, suggesting that

  12. 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.

  13. Formation of multinuclear cells induced by dimethyl sulfoxide: inhibition of cytokinesis and occurrence of novel nuclear division in dictyostelium cells

    OpenAIRE

    Fukui, Y.

    1980-01-01

    Our previous studies showed that 10 percent dimethyl sulfoxide (DMSO) induces the formation of actin microfilament bundles in the cell nucleus together with the dislocation of cortical microfilaments from the plasma membrane. The present study investigated the effects of DMSO on diverse activities mediated by cellular microfilaments as the second step toward assessing potential differences between nuclear and cytoplasmic actins of dictyostelium mucoroides. DMSO was found to reversibly inhibit...

  14. Regulation of cell division and expansion by sugar and auxin signaling

    Directory of Open Access Journals (Sweden)

    Lu eWang

    2013-05-01

    Full Text Available Plant growth and development are modulated by concerted actions of a variety of signaling molecules. In recent years, evidence has emerged on the roles of sugar and auxin signals in diverse aspects of plant growth and development. Here, based on recent progress of genetic analyses and gene expression profiling studies, we summarize the functional similarities, diversities and their interactions of sugar and auxin signals in regulating two major processes of plant development: cell division and cell expansion. We focus on roles of sugar and auxin signaling in both vegetative and reproductive tissues including developing seed.

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

    Directory of Open Access Journals (Sweden)

    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.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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. PMID:25760649

  2. 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.

  3. 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.

  4. 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.

  5. Hibernation as a Far-Reaching Programme for Cell Nucleus Activity Modulation

    Science.gov (United States)

    Malatesta, M.; Biggiogera, M.; Zancanaro, C.

    Maintaining part of the crew under hypometabolic conditions could help with the problems associated with long-term space missions. In the natural world, hibernators represent the most suitable model for a hypometabolic state. These animals are, in fact, able to drastically reduce all metabolic and physiological activities under adverse environmental conditions, but they can rapidly leave the depressed metabolic state as soon as the environment becomes favourable. Hibernators' cellular machinery must therefore undergo adaptive morpho-functional modifications to allow survival. Our studies on tissues of hibernating dormice revealed that the cell nucleus undergoes an important structural reorganisation during the hypometabolic period. Interestingly, despite the drastic reduction in pre-mRNA transcriptional and processing rate, cell nuclei of hibernating dormice never showed features typical of quiescence. Recent analyses revealed that pre-mRNA processing factors undergo an intranuclear redistribution which varies in different tissues. This suggests a programmed intranuclear reorganization of such molecules aimed to an efficient and rapid restoration of pre-mRNA processing upon arousal. Natural hibernation therefore appears as a highly programmed hypometabolic state rather than a simple fall of metabolic and physiological functions.

  6. 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

  7. 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.

  8. 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.

  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

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

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

    Directory of Open Access Journals (Sweden)

    Robert M Cleverley

    2015-01-01

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

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

    Science.gov (United States)

    Seirin Lee, Sungrim

    2016-07-01

    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. PMID:27086039

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

    Science.gov (United States)

    Rasmussen, Ole

    1992-01-01

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

  13. The role of a cell surface inhibitor in early signal transduction associated with the regulation of cell division and differentiation

    Science.gov (United States)

    Johnson, T. C.; Enebo, D. J.; Moos, P. J.; Fattaey, H. K.; Spooner, B. S. (Principal Investigator)

    1992-01-01

    Serum stimulation of quiescent human fibroblast cultures resulted in a hyperphosphorylation of the nuclear retinoblastoma gene susceptibility product (RB). However, serum stimulation in the presence of 9 x 10(-8) M of a purified bovine sialoglycopeptide (SGP) cell surface inhibitor abrogated the hyperphosphorylation of the RB protein and the subsequent progression of cells through the mitotic cycle. The experimental results suggest that the SGP mediated its cell cycle arrest at a site in the cell cycle that was at the time of RB phosphorylation or somewhat upstream of the modification of this regulatory protein of cell division. Both cells serum-deprived and serum stimulated in the presence of the SGP displayed only a hypophosphorylated RB protein, consistent with the SGP-mediated cell cycle arrest point being near the G1/S interface.

  14. 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.

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

    Directory of Open Access Journals (Sweden)

    Pohl Phillip I

    2011-01-01

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

  16. Descending projections from auditory cortex to excitatory and inhibitory cells in the nucleus of the brachium of the inferior colliculus

    Directory of Open Access Journals (Sweden)

    Jeffrey Garrett Mellott

    2014-10-01

    Full Text Available Descending projections from the auditory cortex (AC terminate in subcortical auditory centers from the medial geniculate nucleus (MG to the cochlear nucleus, allowing the AC to modulate the processing of acoustic information at many levels of the auditory system. The nucleus of the brachium of the inferior colliculus (NBIC is a large midbrain auditory nucleus that is a target of these descending cortical projections. The NBIC is a source of several auditory projections, including an ascending projection to the MG. This ascending projection appears to originate from both excitatory and inhibitory NBIC cells, but whether the cortical projections contact either of these cell groups is unknown. In this study, we first combined retrograde tracing and immunochemistry for glutamic acid decarboxylase (GAD, a marker of GABAergic cells to identify GABAergic and non-GABAergic NBIC projections to the MG. Our first result is that GAD-immunopositive cells constitute ~17% of the NBIC to MG projection. We then used anterograde labeling and electron microscopy to examine the AC projection to the NBIC. Our second result is that cortical boutons in the NBIC form synapses with round vesicles and asymmetric synapses, consistent with excitatory effects. Finally, we combined fluorescent anterograde labeling of corticofugal axons with immunochemistry and retrograde labeling of NBIC cells that project to the MG. These final results suggest first that AC axons contact both GAD-negative and GAD-positive NBIC cells and, second, that some of cortically-contacted cells project to the MG. Overall, the results imply that corticofugal projections can modulate both excitatory and inhibitory ascending projections from the NBIC to the auditory thalamus.

  17. Mini-F plasmid genes that couple host cell division to plasmid proliferation.

    OpenAIRE

    Ogura, T; Hiraga, S

    1983-01-01

    A mechanism for stable maintenance of plasmids, besides the replication and partition mechanisms, has been found to be specified by genes of a mini-F plasmid. An oriC plasmid carrying both a mini-F segment necessary for partition [coordinates 46.4-49.4 kilobase pairs (kb) on the F map] and another segment (42.9-43.6 kb), designated ccd (coupled cell division), is more stably maintained than are oriC plasmids carrying only the partition segment; the stability is comparable to that of the paren...

  18. 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

  19. 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

  20. Evaluation of CD24 as a marker to rapidly define the mesenchymal stem cell phenotype and its differentiation in human nucleus pulposus

    Institute of Scientific and Technical Information of China (English)

    Guan Xiaoming; Ma Xun; Zhang Li; Feng Haoyu; Ma Zhuo

    2014-01-01

    Background Recent studies have indicated that human nucleus pulposus contain mesenchymal stem cells (NP-MSCs).However,the immunophenotypic variation of NP-MSCs in vitro was unclear.The present study was conducted to address the immunophenotypic variation of mesenchymal stem cells in nucleus pulposus under continuous proliferation in vitro and show the difference between mesenchymal stem cells and nucleus pulposus cell.Methods Tissue samples were obtained from thoracolumbar burst fracture patients and degenerative disc disease patients who underwent discectomy and fusion procedures.Flow cytometric and laser scanning confocal microscope (LSCM) were used to detect the variation of mesenchymal stem cells in nucleus pulposus which were expressing CD105 and CD24 in condition with or without transforming growth factor β1 (TGF-β1).Results More than 90% of the analyzed primary cells of mesenchymal stem cells in nucleus pulposus fulfilled the general immunophenotyping criteria for MSCs,such as CD44,CD105 and CD29,but the marker of mature NP cells characterized as CD24 was negative.In continuous cultures,the proportion of mesenchymal stem cells which were expressing CD44,CD105 and CD29 in nucleus pulposus gradually decreased.The mesenchymal stem cells in nucleus pulposus cells were positive for CD105 and CD29,with slight positivity for CD44.The CD24 expression gradually increased in proliferation.Biparametric flow cytometry and laser scanning confocal microscopy confirmed the presence of cells which were expressing CD105 and CD24 independently,and only a small part of cells expressed both CD105 and CD24 simultaneously.TGF-β1 could stimulate mesenchymal stem cells in nucleus pulposus to express CD24.Conclusions Non-degenerative and degenerative NP contains mesechymal stem cells.The variation of CD24 can be used as a marker to identify the NP-MSCs differentiation into NP-like cells.

  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. 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.

  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. 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.

  5. 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.

  6. 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

  7. Induction of Chromosomal Aberrations at Fluences of Less Than One HZE Particle per Cell Nucleus

    Science.gov (United States)

    Hada, Megumi; Chappell, Lori J.; Wang, Minli; George, Kerry A.; Cucinotta, Francis A.

    2014-01-01

    The assumption of a linear dose response used to describe the biological effects of high LET radiation is fundamental in radiation protection methodologies. We investigated the dose response for chromosomal aberrations for exposures corresponding to less than one particle traversal per cell nucleus by high energy and charge (HZE) nuclei. Human fibroblast and lymphocyte cells where irradiated with several low doses of <0.1 Gy, and several higher doses of up to 1 Gy with O (77 keV/ (long-s)m), Si (99 keV/ (long-s)m), Fe (175 keV/ (long-s)m), Fe (195 keV/ (long-s)m) or Fe (240 keV/ (long-s)m) particles. Chromosomal aberrations at first mitosis were scored using fluorescence in situ hybridization (FISH) with chromosome specific paints for chromosomes 1, 2 and 4 and DAPI staining of background chromosomes. Non-linear regression models were used to evaluate possible linear and non-linear dose response models based on these data. Dose responses for simple exchanges for human fibroblast irradiated under confluent culture conditions were best fit by non-linear models motivated by a non-targeted effect (NTE). Best fits for the dose response data for human lymphocytes irradiated in blood tubes were a NTE model for O and a linear response model fit best for Si and Fe particles. Additional evidence for NTE were found in low dose experiments measuring gamma-H2AX foci, a marker of double strand breaks (DSB), and split-dose experiments with human fibroblasts. Our results suggest that simple exchanges in normal human fibroblasts have an important NTE contribution at low particle fluence. The current and prior experimental studies provide important evidence against the linear dose response assumption used in radiation protection for HZE particles and other high LET radiation at the relevant range of low doses.

  8. 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

  9. Enzymatically Inactive Procaspase 1 stabilizes the ASC Pyroptosome and Supports Pyroptosome Spreading during Cell Division.

    Science.gov (United States)

    Stein, Robert; Kapplusch, Franz; Heymann, Michael Christian; Russ, Susanne; Staroske, Wolfgang; Hedrich, Christian Michael; Rösen-Wolff, Angela; Hofmann, Sigrun Ruth

    2016-08-26

    Caspase-1 is a key player during the initiation of pro-inflammatory innate immune responses, activating pro-IL-1β in so-called inflammasomes. A subset of patients with recurrent febrile episodes and systemic inflammation of unknown origin harbor mutations in CASP1 encoding caspase-1. CASP1 variants result in reduced enzymatic activity of caspase-1 and impaired IL-1β secretion. The apparent paradox of reduced IL-1β secretion but systemic inflammation led to the hypothesis that CASP1 mutations may result in variable protein interaction clusters, thus activating alternative signaling pathways. To test this hypothesis, we established and characterized an in vitro system of transduced immortalized murine macrophages expressing either WT or enzymatically inactive (p.C284A) procaspase-1 fusion reporter proteins. Macrophages with variant p.C284A caspase-1 did not secrete IL-1β and exhibited reduced inflammatory cell death, referred to as pyroptosis. Caspase-1 and apoptosis-associated speck-like protein containing a CARD (ASC) formed cytosolic macromolecular complexes (so-called pyroptosomes) that were significantly increased in number and size in cells carrying the p.C284A caspase-1 variant compared with WT caspase-1. Furthermore, enzymatically inactive caspase-1 interacted with ASC longer and with increased intensity compared with WT caspase-1. Applying live cell imaging, we documented for the first time that pyroptosomes containing enzymatically inactive variant p.C284A caspase-1 spread during cell division. In conclusion, variant p.C284A caspase-1 stabilizes pyroptosome formation, potentially enhancing inflammation by two IL-1β-independent mechanisms: pyroptosomes convey an enhanced inflammatory stimulus through the recruitment of additional proteins (such as RIP2, receptor interacting protein kinase 2), which is further amplified through pyroptosome and cell division. PMID:27402835

  10. 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).

  11. 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.

  12. 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. PMID:27121010

  13. 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.

  14. 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.

  15. Cell division cycle associated 1 as a novel prognostic biomarker and therapeutic target for oral cancer.

    Science.gov (United States)

    Thang, Phung Manh; Takano, Atsushi; Yoshitake, Yoshihiro; Shinohara, Masanori; Murakami, Yoshinori; Daigo, Yataro

    2016-10-01

    Oral cavity carcinoma (OCC) is one of the most common causes of cancer-related death worldwide and has poor clinical outcome after standard therapies. Therefore, new prognostic biomarkers and therapeutic targets for OCC are urgently needed. We selected cell division cycle associated 1 (CDCA1) as a candidate OCC biomarker. Immunohistochemical analysis confirmed that CDCA1 protein was expressed in 67 of 99 OCC tissues (67.7%), but not in healthy oral epithelia. CDCA1 expression was significantly associated with poor prognosis in OCC patients (P=0.0244). Knockdown of CDCA1 by siRNAs significantly increased apoptosis of tumor cells. These data suggest that CDCA1 represents a novel prognostic biomarker and therapeutic target for OCC. PMID:27499128

  16. 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.

  17. 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.

  18. 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.

  19. Downregulation of cell division cycle 25 homolog C reduces the radiosensitivity and proliferation activity of esophageal squamous cell carcinoma.

    Science.gov (United States)

    Yin, Yachao; Dou, Xiaoyan; Duan, Shimiao; Zhang, Lei; Xu, Quanjing; Li, Hongwei; Li, Duojie

    2016-09-30

    Radiation therapy is one of the most important methods of contemporary cancer treatment. Cells in the G2 and M phases are more sensitive to radiation therapy, and cell division cycle 25 homolog C (CDC25C) is essential in shifting the cell cycle between these two phases. In this study, the knockdown of CDC25C in human esophageal squamous carcinoma EC9706 cells was mediated by transfecting shRNA against human CDC25C-subcloning into pGV248. The levels of CDC25C mRNA and protein expression were assessed by reverse transcription-polymerase chain reaction (RT-PCR) and western blotting, respectively. Moreover, cell proliferation and radiosensitivity were measured. Stable CDC25C-knockdown EC9706 cell lines were successfully established. Furthermore, the proliferation of both control and CDC25C-shRNA-EC9706 cells was inhibited after the cells were treated with increasing X-ray doses, and the proliferation of the control cells was affected more significantly (p<0.05). Moreover, cell colony formation assays allowed us to reach the same conclusion. Taken together, our experiments demonstrated that the knockdown of CDC25C can reduce both the radiotherapy sensitivity and the proliferation activity of EC9706 cells. Thus, CDC25C might be a potential biomarker for radiotherapy treatment. PMID:27188256

  20. Par1b links lumen polarity with LGN-NuMA positioning for distinct epithelial cell division phenotypes

    NARCIS (Netherlands)

    Lazaro-Dieguez, Francisco; Cohen, David; Fernandez, Dawn; Hodgson, Louis; van IJzendoorn, Sven C. D.; Muesch, Anne

    2013-01-01

    Columnar epithelia establish their luminal domains and their mitotic spindles parallel to the basal surface and undergo symmetric cell divisions in which the cleavage furrow bisects the apical domain. Hepatocyte lumina interrupt the lateral domain of neighboring cells perpendicular to two basal doma

  1. Three-dimensional organization of the human interphase nucleus.

    OpenAIRE

    Knoch, Tobias; Münkel, Christian; Waldeck, Waldemar; Langowski, Jörg

    2002-01-01

    textabstractDespite the successful linear sequencing of the human genome its three-dimensional structure is widely unknown, although it is important for gene regulation and replication. For a long time the interphase nucleus has been viewed as a 'spaghetti soup' of DNA without much internal structure, except during cell division. Only recently has it become apparent that chromosomes occupy distinct 'territories' also in interphase. Two models for the detailed folding of the 30 nm chromatin fi...

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

    DEFF Research Database (Denmark)

    Sakamori, Ryotaro; Das, Soumyashree; Yu, Shiyan;

    2012-01-01

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

  4. Spatio-temporal changes in cell division, endoreduplication and expression of cell cycle-related genes in pollinated and plant growth substances-treated ovaries of cucumber.

    Science.gov (United States)

    Fu, F Q; Mao, W H; Shi, K; Zhou, Y H; Yu, J Q

    2010-01-01

    We investigated the temporal and spatial changes in cell division, endoreduplication and expression of cell cycle-related genes in developing cucumber fruits at 0-20 days after anthesis (DAA). Cell division was intense at 0-4 DAA and then decreased until to 8 DAA. Meanwhile, endoreduplication started at 4 DAA and increased gradually to 20 DAA, accompanied by an increase in fruit weight. Cell division was mainly observed in the exocarp, while endoreduplication occurred mostly in the endocarp and pulp. Among the six cell cycle-related genes examined, two mitotic cyclin genes (CycA and CycB) and CDKB had the highest transcript levels within 2 DAA, while transcripts of two CycD3 genes and CDKA peaked at 4 DAA and 20 DAA, respectively. Naphthaleneacetic acid (NAA), N-(2-chloro-4-pyridyl)-N'-phenylurea (CPPU) and 24-epibrassinolide (EBR) all induced parthenocarpic growth as well as active cell division, and enhanced transcripts of cell cycle-related genes. In comparison, gibberellic acid (GA(3)) had little effect on the induction of parthenocarpy and transcripts of cell cycle-related genes. These results provide evidence for the important roles of cell division and endoreduplication during cucumber fruit development, and suggest the essential roles of cell cycle-related genes and plant growth substances in fruit development. PMID:20653892

  5. Amyloid domains in the cell nucleus controlled by nucleoskeletal protein lamin B1 reveal a new pathway of mercury neurotoxicity

    Directory of Open Access Journals (Sweden)

    Florian Arnhold

    2015-02-01

    Full Text Available Mercury (Hg is a bioaccumulating trace metal that globally circulates the atmosphere and waters in its elemental, inorganic and organic chemical forms. While Hg represents a notorious neurotoxicant, the underlying cellular pathways are insufficiently understood. We identify amyloid protein aggregation in the cell nucleus as a novel pathway of Hg-bio-interactions. By mass spectrometry of purified protein aggregates, a subset of spliceosomal components and nucleoskeletal protein lamin B1 were detected as constituent parts of an Hg-induced nuclear aggregome network. The aggregome network was located by confocal imaging of amyloid-specific antibodies and dyes to amyloid cores within splicing-speckles that additionally recruit components of the ubiquitin-proteasome system. Hg significantly enhances global proteasomal activity in the nucleus, suggesting that formation of amyloid speckles plays a role in maintenance of protein homeostasis. RNAi knock down showed that lamin B1 for its part regulates amyloid speckle formation and thus likewise participates in nuclear protein homeostasis. As the Hg-induced cascade of interactions between the nucleoskeleton and protein homeostasis reduces neuronal signalling, amyloid fibrillation in the cell nucleus is introduced as a feature of Hg-neurotoxicity that opens new avenues of future research. Similar to protein aggregation events in the cytoplasm that are controlled by the cytoskeleton, amyloid fibrillation of nuclear proteins may be driven by the nucleoskeleton.

  6. 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...

  7. Single-cell analysis reveals a novel uncultivated magnetotactic bacterium within the candidate division OP3.

    Science.gov (United States)

    Kolinko, Sebastian; Jogler, Christian; Katzmann, Emanuel; Wanner, Gerhard; Peplies, Jörg; Schüler, Dirk

    2012-07-01

    Magnetotactic bacteria (MTB) are a diverse group of prokaryotes that orient along magnetic fields using membrane-coated magnetic nanocrystals of magnetite (Fe(3) O(4) ) or greigite (Fe(3) S(4) ), the magnetosomes. Previous phylogenetic analysis of MTB has been limited to few cultivated species and most abundant members of natural populations, which were assigned to Proteobacteria and the Nitrospirae phyla. Here, we describe a single cell-based approach that allowed the targeted phylogenetic and ultrastructural analysis of the magnetotactic bacterium SKK-01, which was low abundant in sediments of Lake Chiemsee. Morphologically conspicuous single cells of SKK-01 were micromanipulated from magnetically collected multi-species MTB populations, which was followed by whole genome amplification and ultrastructural analysis of sorted cells. Besides intracellular sulphur inclusions, the large ovoid cells of SKK-01 harbour ∼175 bullet-shaped magnetosomes arranged in multiple chains that consist of magnetite as revealed by TEM and EDX analysis. Sequence analysis of 16 and 23S rRNA genes from amplified genomic DNA as well as fluorescence in situ hybridization assigned SKK-01 to the candidate division OP3, which so far lacks any cultivated representatives. SKK-01 represents the first morphotype that can be assigned to the OP3 group as well as the first magnetotactic member of the PVC superphylum. PMID:22003954

  8. 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.

  9. 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.

  10. Human disc cells in monolayer vs 3D culture: cell shape, division and matrix formation

    Directory of Open Access Journals (Sweden)

    Hanley Edward N

    2000-10-01

    Full Text Available Abstract Background The relationship between cell shape, proliferation, and extracellular matrix (ECM production, important aspects of cell behavior, is examined in a little-studied cell type, the human annulus cell from the intervertebral disc, during monolayer vs three-dimensional (3D culture. Results Three experimental studies showed that cells respond specifically to culture microenvironments by changes in cell shape, mitosis and ECM production: 1 Cell passages showed extensive immunohistochemical evidence of Type I and II collagens only in 3D culture. Chondroitin sulfate and keratan sulfate were abundant in both monolayer and 3D cultures. 2 Cells showed significantly greater proliferation in monolayer in the presence of platelet-derived growth factor compared to cells in 3D. 3 Cells on Matrigel™-coated monolayer substrates became rounded and formed nodular colonies, a finding absent during monolayer growth. Conclusions The cell's in vivo interactions with the ECM can regulate shape, gene expression and other cell functions. The shape of the annulus cell changes markedly during life: the young, healthy disc contains spindle shaped cells and abundant collagen. With aging and degeneration, many cells assume a strikingly different appearance, become rounded and are surrounded by unusual accumulations of ECM products. In vitro manipulation of disc cells provides an experimental window for testing how disc cells from given individuals respond when they are grown in environments which direct cells to have either spindle- or rounded-shapes. In vitro assessment of the response of such cells to platelet-derived growth factor and to Matrigel™ showed a continued influence of cell shape even in the presence of a growth factor stimulus. These findings contribute new information to the important issue of the influence of cell shape on cell behavior.

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

    NARCIS (Netherlands)

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

    2015-01-01

    The organization of cells, emerging from cell-cell interactions, can give rise to collective properties. These properties are adaptive when together cells can face environmental challenges that they separately cannot. One particular challenge that is important for microorganisms is migration. In thi

  12. 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

  13. 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.

  14. 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.

  15. PKCα translocation from mitochondria to nucleus is closely related to induction of apoptosis in gastric cancer cells

    Institute of Scientific and Technical Information of China (English)

    WU; Qiao(吴乔); LIU; Su(刘苏); DING; Liang(丁亮); YE; Xiaofeng(叶晓峰); SU; Wenjin(苏文金)

    2002-01-01

    PKCs have been implicated in the regulation of cellular differentiation, proliferation, apoptosis and signal transduction. It was demonstrated in this study that PKC? was located both at mitochondria and in cytosol in gastric cancer cell line BGC-823. Treatment of cells with 12-O-tetradecanoylphorbol-13-acetate (TPA) resulted in the translocation of PKCα from both mitochondria and cytosol to nucleus as clearly shown by laser-scanning-confocal microscopy, while the protein level of PKCα was not changed by TPA treatment as detected by Western blot. The results also revealed that TPA-induced translocation of PKCα was in close association with apoptosis induction, and such association was further affirmed by other experiments where various apoptotic stimuli and specific inhibitors of PKC were used. Taken together, these findings indicate that translocation of PKCα from both mitochondria and cytosol to nucleus in gastric cancer cell is accompanied by induction of apoptosis, and may imply a new mechanism of the potential linking between cell apoptosis and PKCα translocation.

  16. Differentiation of rat adipose tissue-derived mesenchymal stem cells towards a nucleus pulposus-like phenotype in vitro

    Institute of Scientific and Technical Information of China (English)

    XIE Li-wei; FANG Huang; CHEN An-min; LI Feng

    2009-01-01

    Objective: To differentiate rat adipose tissue-derived mesenchymal stem cells (ADSCs) into cells with a nucleus pulposus-like phenotype in vitro,so as to lay a foundation for the cell-based transplantation therapy of degenerated intervertebral discs.Methods: Rat ADSCs were isolated only from the subcutaneous inguinal region and purified by limited dilution.ADSCs of the third passages were analyzed by fluorescence activated cell sorter (FACS) to detect the cell surface markers (Sca-1,CD44,CD45,CD11b).To induce ADSCs towards a nucleus pulposus-like phenotype,ADSCs were immobilized in 3-dimensional alginate hydrogels and cultured in an inducing medium containing transforming growth factor-betal (TGF-β1) under hypoxia (2% O2),while control groups under normoxia (21% O2) in alginate beads in medium with or without the presence of TGF-β1.Semiquantitative reverse transcription polymerase chain reaction (RT-PCR) was carded out to evaluate phenotypic and biosynthetic activities in the process of differentiation.Meanwhile,Alcian blue staining were used to detect the formation of sulfated glycosaminoglycans (GAGs) in the differentiated cells.Results: The purified ADSCs were fibroblast-like and proliferated rapidly in vitro.The flow cytometry showed that ADSCs were positive for Sea-1 and CD44,negative for CD45 and CD11b.The results of RT-PCR manifested that the gene expressions of Sox-9,aggrecan and collagen Ⅱ,which were chondrocyte specific,were upregulated in medium containing TGF-β1 under hypoxia (2% O2).Likewise,gene expression of HIF-la,which was characteristics of intervertebral discs,was also upregulated.Simultaneously,Alcian blue staining exhibited the formation of many GAGs.Conclusions: The approach in our experiment is a simple and effective way to acquire a large quantity of homogenous ADSCs.Rat ADSCs can be differentiated into nucleus pulposus-like cells.ADSCs may replace bone marrow mesenchymal stem cells as a new kind of seed cells in regeneration of

  17. 3D/4D architecture of chromosomal break point regions in the cell nucleus following irradiation of normal cells and tumor cells

    International Nuclear Information System (INIS)

    The development of an effective analytical methodology for a correct description of oncogenic chromosomal aberrations is the challenge of medical radiobiology with respect to preventive therapeutic methods. Scope of the project was a better understanding of the behavior of break point regions dependent on the genome loci, the chromatin folding, the involved repair proteins and the beam quality with respect to an improvement and an efficient prognosis of the health consequences following radiation exposure. New microscopic insights in the normal cell nucleus are supposed to allow a better understanding of the spatial interactions on a molecular scale.

  18. A systematic analysis of cell cycle regulators in yeast reveals that most factors act independently of cell size to control initiation of division.

    Directory of Open Access Journals (Sweden)

    Scott A Hoose

    Full Text Available Upstream events that trigger initiation of cell division, at a point called START in yeast, determine the overall rates of cell proliferation. The identity and complete sequence of those events remain unknown. Previous studies relied mainly on cell size changes to identify systematically genes required for the timely completion of START. Here, we evaluated panels of non-essential single gene deletion strains for altered DNA content by flow cytometry. This analysis revealed that most gene deletions that altered cell cycle progression did not change cell size. Our results highlight a strong requirement for ribosomal biogenesis and protein synthesis for initiation of cell division. We also identified numerous factors that have not been previously implicated in cell cycle control mechanisms. We found that CBS, which catalyzes the synthesis of cystathionine from serine and homocysteine, advances START in two ways: by promoting cell growth, which requires CBS's catalytic activity, and by a separate function, which does not require CBS's catalytic activity. CBS defects cause disease in humans, and in animals CBS has vital, non-catalytic, unknown roles. Hence, our results may be relevant for human biology. Taken together, these findings significantly expand the range of factors required for the timely initiation of cell division. The systematic identification of non-essential regulators of cell division we describe will be a valuable resource for analysis of cell cycle progression in yeast and other organisms.

  19. 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...

  20. LIN-39/Hox triggers cell division and represses EFF-1/fusogen-dependent vulval cell fusion

    OpenAIRE

    Shemer, Gidi; Podbilewicz, Benjamin

    2002-01-01

    General mechanisms by which Hox genes establish cell fates are known. However, a few Hox effectors mediating cell behaviors have been identified. Here we found the first effector of LIN-39/HoxD4/Dfd in Caenorhabditis elegans. In specific vulval precursor cells (VPCs), LIN-39 represses early and late expression of EFF-1, a membrane protein essential for cell fusion. Repression of eff-1 is also achieved by the activity of CEH-20/Exd/Pbx, a known cofactor of Hox proteins. Unfused VPCs in lin-39(...

  1. 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.

  2. 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.

  3. 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.

  4. Ciprofloxacin Derivatives Affect Parasite Cell Division and Increase the Survival of Mice Infected with Toxoplasma gondii.

    Directory of Open Access Journals (Sweden)

    Erica S Martins-Duarte

    Full Text Available Toxoplasmosis, caused by the protozoan Toxoplasma gondii, is a worldwide disease whose clinical manifestations include encephalitis and congenital malformations in newborns. Previously, we described the synthesis of new ethyl-ester derivatives of the antibiotic ciprofloxacin with ~40-fold increased activity against T. gondii in vitro, compared with the original compound. Cipro derivatives are expected to target the parasite's DNA gyrase complex in the apicoplast. The activity of these compounds in vivo, as well as their mode of action, remained thus far uncharacterized. Here, we examined the activity of the Cipro derivatives in vivo, in a model of acute murine toxoplasmosis. In addition, we investigated the cellular effects T. gondii tachyzoites in vitro, by immunofluorescence and transmission electron microscopy (TEM. When compared with Cipro treatment, 7-day treatments with Cipro derivatives increased mouse survival significantly, with 13-25% of mice surviving for up to 60 days post-infection (vs. complete lethality 10 days post-infection, with Cipro treatment. Light microscopy examination early (6 and 24h post-infection revealed that 6-h treatments with Cipro derivatives inhibited the initial event of parasite cell division inside host cells, in an irreversible manner. By TEM and immunofluorescence, the main cellular effects observed after treatment with Cipro derivatives and Cipro were cell scission inhibition--with the appearance of 'tethered' parasites--malformation of the inner membrane complex, and apicoplast enlargement and missegregation. Interestingly, tethered daughter cells resulting from Cipro derivatives, and also Cipro, treatment did not show MORN1 cap or centrocone localization. The biological activity of Cipro derivatives against C. parvum, an apicomplexan species that lacks the apicoplast, is, approximately, 50 fold lower than that in T. gondii tachyzoites, supporting that these compounds targets the apicoplast. Our results

  5. 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; da Silva, Cristiane França; Soeiro, Maria de Nazaré C; 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 that Cipro

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

    Directory of Open Access Journals (Sweden)

    Takahito Yumoto

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

  7. 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

  8. Y-like retinal ganglion cells innervate the dorsal raphe nucleus in the Mongolian gerbil (Meriones unguiculatus.

    Directory of Open Access Journals (Sweden)

    Liju Luan

    Full Text Available BACKGROUND: The dorsal raphe nucleus (DRN of the mesencephalon is a complex multi-functional and multi-transmitter nucleus involved in a wide range of behavioral and physiological processes. The DRN receives a direct input from the retina. However little is known regarding the type of retinal ganglion cell (RGC that innervates the DRN. We examined morphological characteristics and physiological properties of these DRN projecting ganglion cells. METHODOLOGY/PRINCIPAL FINDINGS: The Mongolian gerbils are highly visual rodents with a diurnal/crepuscular activity rhythm. It has been widely used as experimental animals of various studies including seasonal affective disorders and depression. Young adult gerbils were used in the present study. DRN-projecting RGCs were identified following retrograde tracer injection into the DRN, characterized physiologically by extracellular recording and morphologically after intracellular filling. The result shows that DRN-projecting RGCs exhibit morphological characteristics typical of alpha RGCs and physiological response properties of Y-cells. Melanopsin was not detected in these RGCs and they show no evidence of intrinsic photosensitivity. CONCLUSIONS/SIGNIFICANCE: These findings suggest that RGCs with alpha-like morphology and Y-like physiology appear to perform a non-imaging forming function and thus may participate in the modulation of DRN activity which includes regulation of sleep and mood.

  9. 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.

  10. Structure of the bacterial cell division determinant GpsB and its interaction with penicillin-binding proteins.

    Science.gov (United States)

    Rismondo, Jeanine; Cleverley, Robert M; Lane, Harriet V; Großhennig, Stephanie; Steglich, Anne; Möller, Lars; Mannala, Gopala Krishna; Hain, Torsten; Lewis, Richard J; Halbedel, Sven

    2016-03-01

    Each bacterium has to co-ordinate its growth with division to ensure genetic stability of the population. Consequently, cell division and growth are tightly regulated phenomena, albeit different bacteria utilise one of several alternative regulatory mechanisms to maintain control. Here we consider GpsB, which is linked to cell growth and division in Gram-positive bacteria. ΔgpsB mutants of the human pathogen Listeria monocytogenes show severe lysis, division and growth defects due to distortions of cell wall biosynthesis. Consistent with this premise, GpsB interacts both in vitro and in vivo with the major bi-functional penicillin-binding protein. We solved the crystal structure of GpsB and the interaction interfaces in both proteins are identified and validated. The inactivation of gpsB results in strongly attenuated virulence in animal experiments, comparable in degree to classical listerial virulence factor mutants. Therefore, GpsB is essential for in vitro and in vivo growth of a highly virulent food-borne pathogen, suggesting that GpsB could be a target for the future design of novel antibacterials. PMID:26575090

  11. Different Degree in Proteasome Malfunction Has Various Effects on Root Growth Possibly through Preventing Cell Division and Promoting Autophagic Vacuolization

    OpenAIRE

    Xianyong Sheng; Qian Wei; Liping Jiang; Xue Li; Yuan Gao; Li Wang

    2012-01-01

    The ubiquitin/proteasome pathway plays a vital role in plant development. But the effects of proteasome malfunction on root growth, and the mechanism underlying this involvement remains unclear. In the present study, the effects of proteasome inhibitors on Arabidopsis root growth were studied through the analysis of the root length, and meristem size and cell length in maturation zone using FM4-64, and cell-division potential using GFP fusion cyclin B, and accumulation of ubiquitinated protei...

  12. 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.

  13. Different degree in proteasome malfunction has various effects on root growth possibly through preventing cell division and promoting autophagic vacuolization.

    Directory of Open Access Journals (Sweden)

    Xianyong Sheng

    Full Text Available The ubiquitin/proteasome pathway plays a vital role in plant development. But the effects of proteasome malfunction on root growth, and the mechanism underlying this involvement remains unclear. In the present study, the effects of proteasome inhibitors on Arabidopsis root growth were studied through the analysis of the root length, and meristem size and cell length in maturation zone using FM4-64, and cell-division potential using GFP fusion cyclin B, and accumulation of ubiquitinated proteins using immunofluorescence labeling, and autophagy activity using LysoTracker and MDC. The results indicated that lower concentration of proteasome inhibitors promoted root growth, whereas higher concentration of inhibitors had the opposite effects. The accumulation of cyclin B was linked to MG132-induced decline in meristem size, indicating that proteasome malfunction prevented cell division. Besides, MG132-induced accumulation of the ubiquitinated proteins was associated with the increasing fluorescence signal of LysoTracker and MDC in the elongation zone, revealing a link between the activation of autophagy and proteasome malfunction. These results suggest that weak proteasome malfunction activates moderate autophagy and promotes cell elongation, which compensates the inhibitor-induced reduction of cell division, resulting in long roots. Whereas strong proteasome malfunction induces severe autophagy and disturbs cell elongation, resulting in short roots.

  14. The RNA binding protein Larp1 regulates cell division, apoptosis and cell migration.

    Science.gov (United States)

    Burrows, Carla; Abd Latip, Normala; Lam, Sarah-Jane; Carpenter, Lee; Sawicka, Kirsty; Tzolovsky, George; Gabra, Hani; Bushell, Martin; Glover, David M; Willis, Anne E; Blagden, Sarah P

    2010-09-01

    The RNA binding protein Larp1 was originally shown to be involved in spermatogenesis, embryogenesis and cell-cycle progression in Drosophila. Our data show that mammalian Larp1 is found in a complex with poly A binding protein and eukaryote initiation factor 4E and is associated with 60S and 80S ribosomal subunits. A reduction in Larp1 expression by siRNA inhibits global protein synthesis rates and results in mitotic arrest and delayed cell migration. Consistent with these data we show that Larp1 protein is present at the leading edge of migrating cells and interacts directly with cytoskeletal components. Taken together, these data suggest a role for Larp1 in facilitating the synthesis of proteins required for cellular remodelling and migration. PMID:20430826

  15. Genetic cell targeting uncovers specific neuronal types and distinct subregions in the bed nucleus of the stria terminalis.

    Science.gov (United States)

    Nguyen, Amanda Q; Dela Cruz, Julie A D; Sun, Yanjun; Holmes, Todd C; Xu, Xiangmin

    2016-08-15

    The bed nucleus of the stria terminalis (BNST) plays an important role in fear, stress, and anxiety. It contains a collection of subnuclei delineated by gross cytoarchitecture features; however, there has yet to be a systematic examination of specific BNST neuronal types and their associated neurochemical makeup. The present study focuses on improved characterization of the anterior BNST based on differing molecular and chemical expression aided by mouse genetics. Specific Cre driver lines crossed with a fluorescent reporter line were used for genetic cell targeting and immunochemical staining. Using this new approach, we were able to robustly identify specific excitatory and inhibitory cell types in the BNST. The presence and distribution of excitatory neurons were firmly established; glutamatergic neurons in the anterior BNST accounted for about 14% and 31% of dorsal and ventral BNST cells, respectively. GABAergic neurons expressing different isoforms of glutamic acid decarboxylase were found to have differential subregional distributions. Almost no parvalbumin-expressing cells were found in the BNST, while somatostatin-expressing cells and calretinin-expressing cells account for modest proportions of BNST cells. In addition, vasoactive intestinal peptide-expressing axonal plexuses were prominent in the oval and juxtacapsular subregions. In addition, we discovered that corticotropin-releasing hormone-expressing cells contain GABAergic and glutamatergic subpopulations. Together, this study reveals new information on excitatory and inhibitory neurons in the BNST, which will facilitate genetic dissection and functional studies of BNST subregions. J. Comp. Neurol. 524:2379-2399, 2016. © 2016 Wiley Periodicals, Inc. PMID:26718312

  16. 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. PMID:23989670

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. Culture of nucleus pulposus cells from intervertebral disc on self-assembling KLD-12 peptide hydrogel scaffold

    International Nuclear Information System (INIS)

    KLD-12 peptide is a new self-assembling biomaterial and it has been used as cell scaffold for cartilage repair. In this study, self-assembled KLD-12 peptide nanofiber was fabricated and the biocompatibility of this scaffold for nucleus pulposus (NP) cells was evaluated. The structure of this scaffold was characterized by atomic force microscopy (AFM). This hydrogel was structurally integral and homogeneous. KLD-12 peptide was able to self-assemble into nanofibers with a diameter of 10-30 nm (mean: 13.7 ± 4.7 nm) and a length of hundreds of nanometers. Two-week culture of rabbits NP cells in this scaffold showed that the self-assembled hydrogel maintained the live cell number by 93% and the cell viability increased gradually with the culture time. The expression of type II collagen mRNA was further confirmed by reverse transcription polymerase chain reaction (RT-PCR). The expression of type II collagen was high in the hydrogel, however, type I collagen expression was observed in few cells. Furthermore, GAG content increased gradually accompanied with the extension of culture time. In conclusion, this self-assembled nanofiber scaffold provided a conducive microenvironment for NP cell to survive and proliferate in vitro.

  2. 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.

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

    Science.gov (United States)

    Livanos, Pantelis; Galatis, Basil; Apostolakos, Panagiotis

    2016-07-01

    Subsidiary cell generation in Poaceae is an outstanding example of local intercellular stimulation. An inductive stimulus emanates from the guard cell mother cells (GMCs) towards their laterally adjacent subsidiary cell mother cells (SMCs) and triggers the asymmetrical division of the latter. Indole-3-acetic acid (IAA) immunolocalization in Zea mays protoderm confirmed that the GMCs function as local sources of auxin and revealed that auxin is polarly accumulated between GMCs and SMCs in a timely-dependent manner. Besides, staining techniques showed that reactive oxygen species (ROS) exhibit a closely similar, also time-dependent, pattern of appearance suggesting ROS implication in subsidiary cell formation. This phenomenon was further investigated by using the specific NADPH-oxidase inhibitor diphenylene iodonium, the ROS scavenger N-acetyl-cysteine, menadione which leads to ROS overproduction, and H2O2. Treatments with diphenylene iodonium, N-acetyl-cysteine, and menadione specifically blocked SMC polarization and asymmetrical division. In contrast, H2O2 promoted the establishment of SMC polarity and subsequently subsidiary cell formation in "younger" protodermal areas. Surprisingly, H2O2 favored the asymmetrical division of the intervening cells of the stomatal rows leading to the creation of extra apical subsidiary cells. Moreover, H2O2 altered IAA localization, whereas synthetic auxin analogue 1-napthaleneacetic acid enhanced ROS accumulation. Combined treatments with ROS modulators along with 1-napthaleneacetic acid or 2,3,5-triiodobenzoic acid, an auxin efflux inhibitor, confirmed the crosstalk between ROS and auxin functioning during subsidiary cell generation. Collectively, our results demonstrate that ROS are critical partners of auxin during development of Z. mays stomatal complexes. The interplay between auxin and ROS seems to be spatially and temporarily regulated. PMID:26250135

  4. 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.

  5. 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. PMID:27113856

  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. A Systematic Analysis of Cell Cycle Regulators in Yeast Reveals That Most Factors Act Independently of Cell Size to Control Initiation of Division

    OpenAIRE

    Scott A Hoose; Jeremy A Rawlings; Kelly, Michelle M.; M Camille Leitch; Ababneh, Qotaiba O; Robles, Juan P.; David Taylor; Hoover, Evelyn M.; Bethel Hailu; McEnery, Kayla A.; S Sabina Downing; Deepika Kaushal; Yi Chen; Alex Rife; Kirtan A Brahmbhatt

    2012-01-01

    Upstream events that trigger initiation of cell division, at a point called START in yeast, determine the overall rates of cell proliferation. The identity and complete sequence of those events remain unknown. Previous studies relied mainly on cell size changes to identify systematically genes required for the timely completion of START. Here, we evaluated panels of non-essential single gene deletion strains for altered DNA content by flow cytometry. This analysis revealed that most gene dele...

  8. 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.

  9. 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.

  10. 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. PMID:9199372

  11. 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.

  12. 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.

  13. Variations in gene and protein expression in canine chondrodystrophic nucleus pulposus cells following long-term three-dimensional culture.

    Directory of Open Access Journals (Sweden)

    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.

  14. 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.

  15. 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.

  16. 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.

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

    International Nuclear Information System (INIS)

    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

  18. On the properties and origin of the GABAB inhibitory postsynaptic potential recorded in morphologically identified projection cells of the cat dorsal lateral geniculate nucleus.

    Science.gov (United States)

    Soltesz, I; Lightowler, S; Leresche, N; Crunelli, V

    1989-01-01

    Intracellular recordings were performed from projection cells of the cat dorsal lateral geniculate nucleus in vitro to investigate the properties and origin of optic tract evoked inhibitory postsynaptic potentials mediated by GABAB receptors and their relationship to the physiologically different cell classes present in this nucleus. In all three main laminae of the dorsal lateral geniculate nucleus, stimulation of the optic tract evoked an excitatory postsynaptic potential followed by two inhibitory postsynaptic potentials. The first is a GABAA receptor mediated inhibitory postsynaptic potential since it was blocked by bicuculline, reversed in polarity following intracellular Cl- injection and had a reversal potential similar to the bicuculline sensitive hyperpolarizing effect of GABA. The second is a GABAB receptor mediated inhibitory postsynaptic potential. Its amplitude was not linearly related to membrane potential (maximal amplitude at -60 mV), it decreased when using frequencies of stimulation higher than 0.05 Hz and it was reversibly increased by addition of bicuculline to the perfusion medium. The reversal potential of GABAB inhibitory postsynaptic potentials was dependent on the extracellular K+ concentration but did not change in the presence of bicuculline or when recording with Cl- filled microelectrodes. While GABAA inhibitory postsynaptic potentials always abolished repetitive firing of projection cells, GABAB inhibitory postsynaptic potentials were able to block weak firing but unable to decrease strong activation of projection cells evoked by direct current injection. Optic tract evoked GABAB (as well as GABAA) inhibitory postsynaptic potentials could be recorded in slices which did not include the perigeniculate nucleus, thus indicating that they are generated by the interneurons of the dorsal lateral geniculate nucleus. Using intracellular injection of horseradish peroxidase, we have found that the GABAB inhibitory postsynaptic potentials are

  19. The nucleus of differentiated root plant cells: modifications induced by arbuscular mycorrhizal fungi

    Directory of Open Access Journals (Sweden)

    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.

  20. 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.

  1. The ups and downs of somatic cell nucleus transfer (SCNT) in humans

    OpenAIRE

    Fulka, Josef; Langerova, Alena; Loi, Pasqualino; Ptak, Grazyna; Albertini, David; Fulka, Helena

    2013-01-01

    Achieving successful somatic cell nuclear transfer (SCNT) in the human and subhuman primate relative to other mammals has been questioned for a variety of technical and logistical issues. Here we summarize the gradual evolution of SCNT technology from the perspective of oocyte quality and cell cycle status that has recently led to the demonstration of feasibility in the human for deriving chromosomally normal stem cells lines. With these advances in hand, prospects for therapeutic cloning mus...

  2. Phylogeography, Salinity Adaptations and Metabolic Potential of the Candidate Division KB1 Bacteria Based on a Partial Single Cell Genome.

    Science.gov (United States)

    Nigro, Lisa M; Hyde, Andrew S; MacGregor, Barbara J; Teske, Andreas

    2016-01-01

    Deep-sea hypersaline anoxic basins and other hypersaline environments contain abundant and diverse microbial life that has adapted to these extreme conditions. The bacterial Candidate Division KB1 represents one of several uncultured groups that have been consistently observed in hypersaline microbial diversity studies. Here we report the phylogeography of KB1, its phylogenetic relationships to Candidate Division OP1 Bacteria, and its potential metabolic and osmotic stress adaptations based on a partial single cell amplified genome of KB1 from Orca Basin, the largest hypersaline seafloor brine basin in the Gulf of Mexico. Our results are consistent with the hypothesis - previously developed based on (14)C incorporation experiments with mixed-species enrichments from Mediterranean seafloor brines - that KB1 has adapted its proteins to elevated intracellular salinity, but at the same time KB1 apparently imports glycine betaine; this compatible solute is potentially not limited to osmoregulation but could also serve as a carbon and energy source. PMID:27597842

  3. Fission yeast Nod1 is a component of cortical nodes involved in cell size control and division site placement.

    Directory of Open Access Journals (Sweden)

    Isabelle Jourdain

    Full Text Available Most cells enter mitosis once they have reached a defined size. In the fission yeast Schizosaccharomyces pombe, mitotic entry is orchestrated by a geometry-sensing mechanism that involves the Cdk1/Cdc2-inhibiting Wee1 kinase. The factors upstream of Wee1 gather together in interphase to form a characteristic medial and cortical belt of nodes. Nodes are also considered to be precursors of the cytokinesis contractile actomyosin ring (CAR. Here we describe a new component of the interphase nodes and cytokinesis rings, which we named Nod1. Consistent with its role in cell size control at division, nod1Δ cells were elongated and epistatic with regulators of Wee1. Through biochemical and localisation studies, we placed Nod1 in a complex with the Rho-guanine nucleotide exchange factor Gef2. Nod1 and Gef2 mutually recruited each other in nodes and Nod1 also assembles Gef2 in rings. Like gef2Δ, nod1Δ cells showed a mild displacement of their division plane and this phenotype was severely exacerbated when the parallel Polo kinase pathway was also compromised. We conclude that Nod1 specifies the division site by localising Gef2 to the mitotic cell middle. Previous work showed that Gef2 in turn anchors factors that control the spatio-temporal recruitment of the actin nucleation machinery. It is believed that the actin filaments originated from the nodes pull nodes together into a single contractile ring. Surprisingly however, we found that node proteins could form pre-ring helical filaments in a cdc12-112 mutant in which nucleation of the actin ring is impaired. Furthermore, the deletion of either nod1 or gef2 created an un-expected situation where different ring components were recruited sequentially rather than simultaneously. At later stages of cytokinesis, these various rings appeared inter-fitted rather than merged. This study brings a new slant to the understanding of CAR assembly and function.

  4. Mechanical trapping of the nucleus on micropillared surfaces inhibits the proliferation of vascular smooth muscle cells but not cervical cancer HeLa cells.

    Science.gov (United States)

    Nagayama, Kazuaki; Hamaji, Yumi; Sato, Yuji; Matsumoto, Takeo

    2015-07-16

    The interaction between cells and the extracellular matrix on a topographically patterned surface can result in changes in cell shape and many cellular functions. In the present study, we demonstrated the mechanical deformation and trapping of the intracellular nucleus using polydimethylsiloxane (PDMS)-based microfabricated substrates with an array of micropillars. We investigated the differential effects of nuclear deformation on the proliferation of healthy vascular smooth muscle cells (SMCs) and cervical cancer HeLa cells. Both types of cell spread normally in the space between micropillars and completely invaded the extracellular microstructures, including parts of their cytoplasm and their nuclei. We found that the proliferation of SMCs but not HeLa cells was dramatically inhibited by cultivation on the micropillar substrates, even though remarkable deformation of nuclei was observed in both types of cells. Mechanical testing with an atomic force microscope and a detailed image analysis with confocal microscopy revealed that SMC nuclei had a thicker nuclear lamina and greater expression of lamin A/C than those of HeLa cells, which consequently increased the elastic modulus of the SMC nuclei and their nuclear mechanical resistance against extracellular microstructures. These results indicate that the inhibition of cell proliferation resulted from deformation of the mature lamin structures, which might be exposed to higher internal stress during nuclear deformation. This nuclear stress-induced inhibition of cell proliferation occurred rarely in cancer cells with deformable nuclei. PMID:26054426

  5. 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. PMID:26876306

  6. 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.

  7. Activation of the c-fos gene in prodynorphin- and proenkephalin-expressing cells of nucleus tractus solitarius after seizures.

    Science.gov (United States)

    Kanter, R K; Erickson, J T; Millhorn, D E

    1994-10-01

    We performed studies to determine the anatomical regions and chemical phenotypes of neurons within the rat medulla oblongata activated by pentylenetetrazole-induced seizures. Activated cells were identified by their expression of the c-fos gene, detected by in situ hybridization for c-fos mRNA and immunocytochemistry for Fos protein. Activated cells were located predominantly in nucleus tractus solitarius (NTS), with c-fos mRNA appearing within 20 min after seizures (peak at 1-2 h), followed by Fos immunoreactivity visible at 1 h (peak at 2-4 h). Neither nonspecific noxious stimulation by intraperitoneal injection of saline nor brief exposure to hypoxic or hypercapnic gas mixtures to stimulate chemoreceptors reproduced this pattern of labeling. Prodynorphin or proenkephalin mRNA, detected by in situ hybridization, was colocalized with Fos immunoreactivity in many NTS cells. Thus, seizures activate neuronal pathways in the medulla oblongata which express genes for endogenous opioids. Potential long-term effects of seizures are suggested by the in situ hybridization finding that NTS prodynorphin mRNA increased 24 h after seizures compared to control levels. PMID:7957742

  8. Selective hair cell ablation and noise exposure lead to different patterns of changes in the cochlea and the cochlear nucleus.

    Science.gov (United States)

    Kurioka, Takaomi; Lee, Min Young; Heeringa, Amarins N; Beyer, Lisa A; Swiderski, Donald L; Kanicki, Ariane C; Kabara, Lisa L; Dolan, David F; Shore, Susan E; Raphael, Yehoash

    2016-09-22

    In experimental animal models of auditory hair cell (HC) loss, insults such as noise or ototoxic drugs often lead to secondary changes or degeneration in non-sensory cells and neural components, including reduced density of spiral ganglion neurons, demyelination of auditory nerve fibers and altered cell numbers and innervation patterns in the cochlear nucleus (CN). However, it is not clear whether loss of HCs alone leads to secondary degeneration in these neural components of the auditory pathway. To elucidate this issue, we investigated changes of central components after cochlear insults specific to HCs using diphtheria toxin receptor (DTR) mice expressing DTR only in HCs and exhibiting complete HC loss when injected with diphtheria toxin (DT). We showed that DT-induced HC ablation has no significant impacts on the survival of auditory neurons, central synaptic terminals, and myelin, despite complete HC loss and profound deafness. In contrast, noise exposure induced significant changes in synapses, myelin and CN organization even without loss of inner HCs. We observed a decrease of neuronal size in the auditory pathway, including peripheral axons, spiral ganglion neurons, and CN neurons, likely due to loss of input from the cochlea. Taken together, selective HC ablation and noise exposure showed different patterns of pathology in the auditory pathway and the presence of HCs is not essential for the maintenance of central synaptic connectivity and myelination. PMID:27403879

  9. 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.

  10. Differential expression of extracellular-signal-regulated kinase 5 (ERK5) in normal and degenerated human nucleus pulposus tissues and cells

    Energy Technology Data Exchange (ETDEWEB)

    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.

  11. 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.

  12. 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; Yue, Kun; Liu, Jiajia; Zhang, Bing; Li, Xugang; Ding, Zhaojun

    2016-09-01

    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

  13. 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

  14. Systemic Control of Cell Division and Endoreduplication by NAA and BAP by Modulating CDKs in Root Tip Cells of Allium cepa

    Directory of Open Access Journals (Sweden)

    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.

  15. SGT, a Hsp90β binding partner, is accumulated in the nucleus during cell apoptosis

    International Nuclear Information System (INIS)

    In this study, we reported that small glutamine-rich TPR-containing protein (SGT) interacted with not only Hsp90α but also Hsp90β. Confocal analysis showed that treatment of cells with Hsp90-specific inhibitor geldanamycin (GA) disrupted the interaction of SGT with Hsp90β and this contributed to the increase of nuclear localization of SGT in HeLa cells. The increased nuclear localization of SGT was further confirmed by the Western blotting in GA-treated HeLa cells and H1299 cells. In our previous study, SGT was found to be a new pro-apoptotic factor, so we wondered whether the sub-cellular localization of SGT was related with cell apoptosis. By confocal analysis we found that the nuclear import of SGT was significantly increased in STS-induced apoptotic HeLa cells, which implied that the sub-cellular localization of SGT was closely associated with Hsp90β and apoptosis

  16. The ClpP protease homologue is required for the transmission traits and cell division of the pathogen Legionella pneumophila

    Directory of Open Access Journals (Sweden)

    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.

  17. [The molecular organizational characteristics of the cell nucleus components at different phases of the mitotic cycle and in the resting state].

    Science.gov (United States)

    S'iakste, N I

    1992-01-01

    Data about the changes of the cell nucleus structure at different levels of its organization are summarized in the review. The data about the change of the DNA break number during the cycle and in resting state are presented and the role of the changes of the repair efficiency in this process is discussed. The changes of the chromatin protein spectrum, the chromatin structure at nucleosomal and supranucleosomal levels, the DNA superhelicity, topoisomerase activity, nuclear matrix composition and structure are discussed as well. The nucleus structure during the S-phase and mitosis and the cycle-related changes of the chromatin structure in lower eukaryotes are reviewed separately.

  18. 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.

  19. Compartmentalization and Cell Division through Molecular Discreteness and Crowding in a Catalytic Reaction Network

    Directory of Open Access Journals (Sweden)

    Atsushi Kamimura

    2014-10-01

    Full Text Available Explanation of the emergence of primitive cellular structures from a set of chemical reactions is necessary to unveil the origin of life and to experimentally synthesize protocells. By simulating a cellular automaton model with a two-species hypercycle, we demonstrate the reproduction of a localized cluster; that is, a protocell with a growth-division process emerges when the replication and degradation speeds of one species are respectively slower than those of the other species, because of overcrowding of molecules as a natural outcome of the replication. The protocell exhibits synchrony between its division process and replication of the minority molecule. We discuss the effects of the crowding molecule on the formation of primitive structures. The generality of this result is demonstrated through the extension of our model to a hypercycle with three molecular species, where a localized layered structure of molecules continues to divide, triggered by the replication of a minority molecule at the center.

  20. The cytological changes of tobacco zygote and proembryo cells induced by beta-glucosyl Yariv reagent suggest the involvement of arabinogalactan proteins in cell division and cell plate formation

    Directory of Open Access Journals (Sweden)

    Yu Miao

    2012-08-01

    Full Text Available Abstract Background In dicotyledonous plant, the first asymmetric zygotic division and subsequent several cell divisions are crucial for proembryo pattern formation and later embryo development. Arabinogalactan proteins (AGPs are a family of extensively glycosylated cell surface proteins that are thought to have important roles in various aspects of plant growth and development, including embryogenesis. Previous results from our laboratory show that AGPs are concerned with tobacco egg cell fertilization and zygotic division. However, how AGPs interact with other factors involved in zygotic division and proembryo development remains unknown. Results In this study, we used the tobacco in vitro zygote culture system and series of meticulous cell biology techniques to investigate the roles of AGPs in zygote and proembryo cell division. For the first time, we examined tobacco proembryo division patterns detailed to every cell division. The bright-field images and statistical results both revealed that with the addition of an exogenous AGPs inhibitor, beta-glucosyl Yariv (beta-GlcY reagent, the frequency of aberrant division increased remarkably in cultured tobacco zygotes and proembryos, and the cell plate specific locations of AGPs were greatly reduced after beta-GlcY treatment. In addition, the accumulations of new cell wall materials were also significantly affected by treating with beta-GlcY. Detection of cellulose components by Calcofluor white stain showed that strong fluorescence was located in the newly formed wall of daughter cells after the zygotic division of in vivo samples and the control samples from in vitro culture without beta-GlcY treatment; while there was only weak fluorescence in the newly formed cell walls with beta-GlcY treatment. Immunocytochemistry examination with JIM5 and JIM7 respectively against the low- and high-esterified pectins displayed that these two pectins located in opposite positions of zygotes and proembryos in

  1. Compartmentalization and Cell Division through Molecular Discreteness and Crowding in a Catalytic Reaction Network

    OpenAIRE

    Atsushi Kamimura; Kunihiko Kaneko

    2014-01-01

    Explanation of the emergence of primitive cellular structures from a set of chemical reactions is necessary to unveil the origin of life and to experimentally synthesize protocells. By simulating a cellular automaton model with a two-species hypercycle, we demonstrate the reproduction of a localized cluster; that is, a protocell with a growth-division process emerges when the replication and degradation speeds of one species are respectively slower than those of the other species, because of ...

  2. A fraction of neurofibromin interacts with PML bodies in the nucleus of the CCF astrocytoma cell line

    Energy Technology Data Exchange (ETDEWEB)

    Godin, Fabienne; Villette, Sandrine; Vallee, Beatrice; Doudeau, Michel; Morisset-Lopez, Severine [Centre de Biophysique Moleculaire, Centre National de la Recherche Scientifique (CNRS), UPR 4301, Universite d' Orleans et INSERM, rue Charles Sadron, 45071 Orleans Cedex 2 (France); Ardourel, Maryvonne; Hevor, Tobias [Laboratoire de Neurobiologie, Universite d' Orleans, BP 6759, 45067 Orleans Cedex 2 (France); Pichon, Chantal [Centre de Biophysique Moleculaire, Centre National de la Recherche Scientifique (CNRS), UPR 4301, Universite d' Orleans et INSERM, rue Charles Sadron, 45071 Orleans Cedex 2 (France); Benedetti, Helene, E-mail: helene.benedetti@cnrs-orleans.fr [Centre de Biophysique Moleculaire, Centre National de la Recherche Scientifique (CNRS), UPR 4301, Universite d' Orleans et INSERM, rue Charles Sadron, 45071 Orleans Cedex 2 (France)

    2012-02-24

    Highlights: Black-Right-Pointing-Pointer We validate the use of specific anti-Nf1 antibodies for immunofluorescence studies. Black-Right-Pointing-Pointer We detect Nf1 in the cytoplasm and nucleus of CCF cells. Black-Right-Pointing-Pointer We demonstrate that Nf1 partially colocalizes with PML nuclear bodies. Black-Right-Pointing-Pointer We demonstrate that there is a direct interaction between a fraction of Nf1 and the PML bodies. -- Abstract: Neurofibromatosis type 1 is a common genetic disease that causes nervous system tumors, and cognitive deficits. It is due to mutations within the NF1 gene, which encodes the Nf1 protein. Nf1 has been shown to be involved in the regulation of Ras, cAMP and actin cytoskeleton dynamics. In this study, using immunofluorescence experiments, we have shown a partial nuclear localization of Nf1 in the astrocytoma cell line: CCF and we have demonstrated that Nf1 partially colocalizes with PML (promyelocytic leukemia) nuclear bodies. A direct interaction between Nf1 and the multiprotein complex has further been demonstrated using 'in situ' proximity ligation assay (PLA).

  3. Cell-type specific oxytocin gene expression from AAV delivered promoter deletion constructs into the rat supraoptic nucleus in vivo.

    Directory of Open Access Journals (Sweden)

    Raymond L Fields

    Full Text Available The magnocellular neurons (MCNs in the hypothalamus selectively express either oxytocin (OXT or vasopressin (AVP neuropeptide genes, a property that defines their phenotypes. Here we examine the molecular basis of this selectivity in the OXT MCNs by stereotaxic microinjections of adeno-associated virus (AAV vectors that contain various OXT gene promoter deletion constructs using EGFP as the reporter into the rat supraoptic nucleus (SON. Two weeks following injection of the AAVs, immunohistochemical assays of EGFP expression from these constructs were done to determine whether the EGFP reporter co-localizes with either the OXT- or AVP-immunoreactivity in the MCNs. The results show that the key elements in the OT gene promoter that regulate the cell-type specific expression the SON are located -216 to -100 bp upstream of the transcription start site. We hypothesize that within this 116 bp domain a repressor exists that inhibits expression specifically in AVP MCNs, thereby leading to the cell-type specific expression of the OXT gene only in the OXT MCNs.

  4. β-Adrenergic activation enhances NMDA-induced current in pyramidal cells of the basolateral nucleus of amygdala

    Institute of Scientific and Technical Information of China (English)

    LIU Xinqiu; CAO Xiaohua; LI Bao-ming

    2005-01-01

    NMDA receptor (NMDA-R) in the amygdala complex is critical for both long-term potentiation (LTP) and formation of conditioned fear memory. It is reported that activation of β-adrenoceptors (β-AR) in the amygdala facilitates LTP and enhances memory consolidation. The present study examined the regulatory effect of β-AR activation on NMDA-R mediated current in pyramidal cells of the basolateral nucleus of amygdala (BLA), using whole-cell recording technique. Bath application of the β-AR agonist isoproterenol enhanced NMDA-induced current, and this facilitatory effect was blocked by co-administered propranolol, a β-AR antagonist. The facilitatory effect of isoproterenol on NMDA-induced current could not be induced when the protein kinase A (PKA) inhibitor Rp-cAMPs was added in electrode internal solution.The present results suggest that β-AR activation in the BLA could modulate NMDA-R activity directly and positively, probably via PKA.

  5. Increased number of TH-immunoreactive cells in the ventral tegmental area after deep brain stimulation of the anterior nucleus of the thalamus.

    Science.gov (United States)

    Dela Cruz, J A D; Hescham, S; Adriaanse, B; Campos, F L; Steinbusch, H W M; Rutten, B P F; Temel, Y; Jahanshahi, A

    2015-09-01

    Dopamine (DA) has been long implicated with the processes of memory. In long-term memory, the hippocampus and ventral tegmental area (VTA) use DA to enhance long-term potentiation, while prefrontal DA D1 receptors are involved in working memory. Deep brain stimulation (DBS) of specific brain areas have been shown to affect memory impairments in animal models. Here, we tested the hypothesis that DBS could reverse memory impairments by increasing the number of dopaminergic cells in the VTA. Rats received DBS at the level of the mammillothalamic tract, the anterior nucleus of the thalamus, and entorhinal cortex before euthanasia. These regions are part of the so-called memory circuit. Brain sections were processed for c-Fos and tyrosine hydroxylase (TH) immunocytochemistry in the VTA and the substantia nigra pars compacta (SNc). c-Fos, TH and c-Fos/TH immunoreactive cells were analyzed by means of stereology and confocal microscopy. Our results showed that DBS of the anterior nucleus of the thalamus induced substantial higher numbers of TH-immunoreactive cells in the VTA, while there were no significant differences between the experimental groups in the number of TH immunoreactive cells in the SNc, c-Fos immunoreactive cells and c-Fos/TH double-labeled cells in both the SNc and VTA. Our findings suggest a phenotypic switch, or neurotransmitter respecification, of DAergic cells specifically in the VTA which may be induced by DBS in the anterior nucleus of the thalamus.

  6. Immobility, inheritance and plasticity of shape of the yeast nucleus

    Directory of Open Access Journals (Sweden)

    Andrulis Erik D

    2007-11-01

    Full Text Available Abstract Background Since S. cerevisiae undergoes closed mitosis, the nuclear envelope of the daughter nucleus is continuous with that of the maternal nucleus at anaphase. Nevertheless, several constitutents of the maternal nucleus are not present in the daughter nucleus. The present study aims to identify proteins which impact the shape of the yeast nucleus and to learn whether modifications of shape are passed on to the next mitotic generation. The Esc1p protein of S. cerevisiae localizes to the periphery of the nucleoplasm, can anchor chromatin, and has been implicated in targeted silencing both at telomeres and at HMR. Results Upon increased Esc1p expression, cell division continues and dramatic elaborations of the nuclear envelope extend into the cytoplasm. These "escapades" include nuclear pores and associate with the nucleolus, but exclude chromatin. Escapades are not inherited by daughter nuclei. This exclusion reflects their relative immobility, which we document in studies of prezygotes. Moreover, excess Esc1p affects the levels of multiple transcripts, not all of which originate at telomere-proximal loci. Unlike Esc1p and the colocalizing protein, Mlp1p, overexpression of selected proteins of the inner nuclear membrane is toxic. Conclusion Esc1p is the first non-membrane protein of the nuclear periphery which – like proteins of the nuclear lamina of higher eukaryotes – can modify the shape of the yeast nucleus. The elaborations of the nuclear envelope ("escapades" which appear upon induction of excess Esc1p are not inherited during mitotic growth. The lack of inheritance of such components could help sustain cell growth when parental nuclei have acquired potentially deleterious characteristics.

  7. Effect of corticosterone and adrenalectomy on NMDA-induced cholinergic cell death in rat magnocellular nucleus basalis

    NARCIS (Netherlands)

    Abraham, [No Value; Veenema, AH; Nyakas, C; Harkany, T; Bohus, BGJ; Luiten, PGM; Ábrahám, I.

    1997-01-01

    The present study demonstrates the effects of adrenalectomy and subcutaneously administered corticosterone on N-methyl-D-aspartate-induced neurodegeneration in the cholinergic magnocellular basal nucleus of the rat, NMDA was unilaterally injected into the nucleus basalis at different plasma corticos

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

    Directory of Open Access Journals (Sweden)

    Pamela eGamba

    2015-04-01

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

  9. SDF-1/CXCR4 axis induces apoptosis of human degenerative nucleus pulposus cells via the NF-κB pathway

    Science.gov (United States)

    LIU, ZONGCHAO; MA, CHUAN; SHEN, JIELIANG; WANG, DAWU; HAO, JIE; HU, ZHENMING

    2016-01-01

    Intervertebral disc degeneration (IVDD) is a major cause of lower back pain, and increased cell apoptosis is a key characteristic of IVDD. The present study aimed to investigate the effects and mechanism of the stromal cell-derived factor-1 (SDF-1)/C-X-C motif chemokine receptor 4 (CXCR4) axis on apoptosis in human degenerative nucleus pulposus cells (NPCs). The expression levels of SDF-1 and CXCR4 in human intervertebral discs (IVD) were determined using immunohistochemistry and western blot analysis. Apoptosis of primary cultured NPCs was quantified by Annexin V/propidium iodide staining following stimulation with SDF-1 and knockdown of CXCR4 using small interfering RNA (siRNA). The association with the nuclear factor-κB (NF-κB) signaling pathway was investigated using CXCR4-siRNA and NF-κB inhibitor, pyrrolidine dithiocarbamate (PDTC), treatment. The results demonstrated that SDF-1 and its receptor, CXCR4, were upregulated in degenerative IVD samples compared with normal samples. Stimulation with SDF-1 increased the level of apoptosis in cultured NPCs, and conversely, the apoptosis level was suppressed post-transfection with CXCR4 siRNA compared with SDF-1 stimulation alone. Furthermore, SDF-1 treatment increased the level of phosphorylated NF-κB subunit P65, which was downregulated following CXCR4 siRNA and PDTC treatment. In addition, CXCR4 siRNA and PDTC inhibited the nuclear translocation of P65, which was induced by SDF-1. Taken together, SDF-1-mediated apoptosis was suppressed by NF-κB inhibition using PDTC. In conclusion, the SDF-1/CXCR4 axis promoted cell apoptosis in human degenerative NPCs via the NF-κB pathway, thus suggesting that SDF-1/CXCR signaling may be a therapeutic target for the treatment of degenerative IVD diseases. PMID:27220474

  10. Effects of age, replicative lifespan and growth rate of human nucleus pulposus cells on selecting age range for cell-based biological therapies for degenerative disc diseases.

    Science.gov (United States)

    Lee, J S; Lee, S M; Jeong, S W; Sung, Y G; Lee, J H; Kim, K W

    2016-07-01

    Autologous disc cell implantation, growth factors and gene therapy appear to be promising therapies for disc regeneration. Unfortunately, the replicative lifespan and growth kinetics of human nucleus pulposus (NP) cells related to host age are unclear. We investigated the potential relations among age, replicative lifespan and growth rate of NP cells, and determined the age range that is suitable for cell-based biological therapies for degenerative disc diseases. We used NP tissues classified by decade into five age groups: 30s, 40s, 50s, 60s and 70s. The mean cumulative population doubling level (PDL) and population doubling rate (PDR) of NP cells were assessed by decade. We also investigated correlations between cumulative PDL and age, and between PDR and age. The mean cumulative PDL and PDR decreased significantly in patients in their 60s. The mean cumulative PDL and PDR in the younger groups (30s, 40s and 50s) were significantly higher than those in the older groups (60s and 70s). There also were significant negative correlations between cumulative PDL and age, and between PDR and age. We found that the replicative lifespan and growth rate of human NP cells decreased with age. The replicative potential of NP cells decreased significantly in patients 60 years old and older. Young individuals less than 60 years old may be suitable candidates for NP cell-based biological therapies for treating degenerative disc diseases. PMID:27149303

  11. A novel human gene spindlin1,encoding a protein localized in the cell nucleus and inducing NIH3T3 cell's transformation

    Institute of Scientific and Technical Information of China (English)

    GAO Yanhong; QIN Lipeng; ZHANG Peng; CHEN Lin; YUAN Hongfeng; BAI Cixian; YAN Fang; YUE Wen; PEI Xuetao

    2004-01-01

    A novel human gene, spindlin1, recently cloned in our laboratory, is highly expressed in the tissue of ovary cancer. To study its biological function, a vector expressing green fluorescent-spindlin1 fusion protein was constructed and transfected into COS-7 and NIH3T3 cells by lipofectamine methods. The results showed that the fusion protein pEGFP-N1-spindlin1 was localized in the nucleus of COS-7 and NIH3T3 cells. NIH3T3 cells which could stably express spindlin1 as a result of RT-PCR analysis compared with the parental NIH3T3 cells displayed a complete morphological change, improved the cell growth and increased the percentage of cells in G2/M phase (12.6% vs control cells at 3.4%). Furthermore, overexpressed spindlin1 cells formed colonies in soft agar, more motile in migration assay in vitro and formed tumors in nude mice. Our findings provide direct evidence that spindlin1 gene may be a prooncogene which is associated with tumorigenesis.

  12. Three-dimensional organization of the human interphase nucleus: Experiments compared to simulations.

    OpenAIRE

    Knoch, Tobias; Münkel, Christian; Waldeck, Waldemar; Langowski, Jörg

    2000-01-01

    markdownabstractDespite the successful linear sequencing of the human genome its three-dimensional structure is widely unknown, although it is important for gene regulation and replication. For a long time the interphase nucleus has been viewed as a 'spaghetti soup' of DNA without much internal structure, except during cell division. Only recently has it become apparent that chromosomes occupy distinct 'territories' also in interphase. Two models for the detailed folding of the 30 nm chromati...

  13. A highly efficient method for generation of therapeutic quality human pluripotent stem cells by using naive induced pluripotent stem cells nucleus for nuclear transfer

    Directory of Open Access Journals (Sweden)

    Madhusudana Girija Sanal

    2014-09-01

    Full Text Available Even after several years since the discovery of human embryonic stem cells and induced pluripotent stem cells (iPSC, we are still unable to make any significant therapeutic benefits out of them such as cell therapy or generation of organs for transplantation. Recent success in somatic cell nuclear transfer (SCNT made it possible to generate diploid embryonic stem cells, which opens up the way to make high-quality pluripotent stem cells. However, the process is highly inefficient and hence expensive compared to the generation of iPSC. Even with the latest SCNT technology, we are not sure whether one can make therapeutic quality pluripotent stem cell from any patient’s somatic cells or by using oocytes from any donor. Combining iPSC technology with SCNT, that is, by using the nucleus of the candidate somatic cell which got reprogrammed to pluripotent state instead that of the unmodified nucleus of the candidate somatic cell, would boost the efficiency of the technique, and we would be able to generate therapeutic quality pluripotent stem cells. Induced pluripotent stem cell nuclear transfer (iPSCNT combines the efficiency of iPSC generation with the speed and natural reprogramming environment of SCNT. The new technique may be called iPSCNT. This technique could prove to have very revolutionary benefits for humankind. This could be useful in generating organs for transplantation for patients and for reproductive cloning, especially for childless men and women who cannot have children by any other techniques. When combined with advanced gene editing techniques (such as CRISPR-Cas system this technique might also prove useful to those who want to have healthy children but suffer from inherited diseases. The current code of ethics may be against reproductive cloning. However, this will change with time as it happened with most of the revolutionary scientific breakthroughs. After all, it is the right of every human to have healthy offspring and it is

  14. An organism arises from every nucleus.

    OpenAIRE

    Nurullah Keklikoglu

    2009-01-01

    The fact that, cloning using somatic cell nuclear transfer (SCNT) method has been performed, opened new horizons for cloning, and changed the way of our understanding and approach to cell and nucleus. The progress in cloning technology, brought the anticipation of the ability to clone an organism from each somatic cell nucleus. Therefore, the 'Cell Theory' is about to take the additional statement as "An organism arises from every nucleus". The development of gene targeting procedures which c...

  15. 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.

  16. Angular velocity and head direction signals recorded from the dorsal tegmental nucleus of gudden in the rat: implications for path integration in the head direction cell circuit.

    Science.gov (United States)

    Sharp, P E; Tinkelman, A; Cho, J

    2001-06-01

    When a rat navigates through space, head direction (HD) cells provide an ongoing signal of the rat's directional heading. It is thought that these cells rely, in part, on angular path integration of the rat's head movements. This integration requires that the HD cell system receive information about angular head movements and that this information be combined with the current directional signal, to generate the next "predicted" direction. Recent data suggest that the dorsal tegmental nucleus (DTN) may play a critical role in helping to generate the HD cell signal. To test this, recordings were made from cells in the DTN in freely moving rats. The following cell types were found: (a) "classic" HD cells, (b) angular velocity cells, and (c) cells that fired as a function of both head direction and angular velocity. Thus, DTN cells exhibit firing characteristics that are critical to the neural circuit hypothesized for generation of the HD cell signal. PMID:11439447

  17. Oriented Cell Division in the C. elegans Embryo Is Coordinated by G-Protein Signaling Dependent on the Adhesion GPCR LAT-1

    Science.gov (United States)

    Fiedler, Franziska; Sastradihardja, Tania; Binder, Claudia; Schnabel, Ralf; Kungel, Jana; Rothemund, Sven; Hennig, Christian; Schöneberg, Torsten; Prömel, Simone

    2015-01-01

    Orientation of spindles and cell division planes during development of many species ensures that correct cell-cell contacts are established, which is vital for proper tissue formation. This is a tightly regulated process involving a complex interplay of various signals. The molecular mechanisms underlying several of these pathways are still incompletely understood. Here, we identify the signaling cascade of the C. elegans latrophilin homolog LAT-1, an essential player in the coordination of anterior-posterior spindle orientation during the fourth round of embryonic cell division. We show that the receptor mediates a G protein-signaling pathway revealing that G-protein signaling in oriented cell division is not solely GPCR-independent. Genetic analyses showed that through the interaction with a Gs protein LAT-1 elevates intracellular cyclic AMP (cAMP) levels in the C. elegans embryo. Stimulation of this G-protein cascade in lat-1 null mutant nematodes is sufficient to orient spindles and cell division planes in the embryo in the correct direction. Finally, we demonstrate that LAT-1 is activated by an intramolecular agonist to trigger this cascade. Our data support a model in which a novel, GPCR-dependent G protein-signaling cascade mediated by LAT-1 controls alignment of cell division planes in an anterior-posterior direction via a metabotropic Gs-protein/adenylyl cyclase pathway by regulating intracellular cAMP levels. PMID:26505631

  18. Oriented Cell Division in the C. elegans Embryo Is Coordinated by G-Protein Signaling Dependent on the Adhesion GPCR LAT-1.

    Directory of Open Access Journals (Sweden)

    Antje Müller

    2015-10-01

    Full Text Available Orientation of spindles and cell division planes during development of many species ensures that correct cell-cell contacts are established, which is vital for proper tissue formation. This is a tightly regulated process involving a complex interplay of various signals. The molecular mechanisms underlying several of these pathways are still incompletely understood. Here, we identify the signaling cascade of the C. elegans latrophilin homolog LAT-1, an essential player in the coordination of anterior-posterior spindle orientation during the fourth round of embryonic cell division. We show that the receptor mediates a G protein-signaling pathway revealing that G-protein signaling in oriented cell division is not solely GPCR-independent. Genetic analyses showed that through the interaction with a Gs protein LAT-1 elevates intracellular cyclic AMP (cAMP levels in the C. elegans embryo. Stimulation of this G-protein cascade in lat-1 null mutant nematodes is sufficient to orient spindles and cell division planes in the embryo in the correct direction. Finally, we demonstrate that LAT-1 is activated by an intramolecular agonist to trigger this cascade. Our data support a model in which a novel, GPCR-dependent G protein-signaling cascade mediated by LAT-1 controls alignment of cell division planes in an anterior-posterior direction via a metabotropic Gs-protein/adenylyl cyclase pathway by regulating intracellular cAMP levels.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1991-12-01

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

  20. SDF‑1/CXCR4 axis induces apoptosis of human degenerative nucleus pulposus cells via the NF‑κB pathway.

    Science.gov (United States)

    Liu, Zongchao; Ma, Chuan; Shen, Jieliang; Wang, Dawu; Hao, Jie; Hu, Zhenming

    2016-07-01

    Intervertebral disc degeneration (IVDD) is a major cause of lower back pain, and increased cell apoptosis is a key characteristic of IVDD. The present study aimed to investigate the effects and mechanism of the stromal cell‑derived factor‑1 (SDF‑1)/C‑X‑C motif chemokine receptor 4 (CXCR4) axis on apoptosis in human degenerative nucleus pulposus cells (NPCs). The expression levels of SDF‑1 and CXCR4 in human intervertebral discs (IVD) were determined using immunohistochemistry and western blot analysis. Apoptosis of primary cultured NPCs was quantified by Annexin V/propidium iodide staining following stimulation with SDF‑1 and knockdown of CXCR4 using small interfering RNA (siRNA). The association with the nuclear factor‑κB (NF‑κB) signaling pathway was investigated using CXCR4‑siRNA and NF‑κB inhibitor, pyrrolidine dithiocarbamate (PDTC), treatment. The results demonstrated that SDF‑1 and its receptor, CXCR4, were upregulated in degenerative IVD samples compared with normal samples. Stimulation with SDF‑1 increased the level of apoptosis in cultured NPCs, and conversely, the apoptosis level was suppressed post‑transfection with CXCR4 siRNA compared with SDF‑1 stimulation alone. Furthermore, SDF‑1 treatment increased the level of phosphorylated NF‑κB subunit P65, which was downregulated following CXCR4 siRNA and PDTC treatment. In addition, CXCR4 siRNA and PDTC inhibited the nuclear translocation of P65, which was induced by SDF‑1. Taken together, SDF‑1‑mediated apoptosis was suppressed by NF‑κB inhibition using PDTC. In conclusion, the SDF‑1/CXCR4 axis promoted cell apoptosis in human degenerative NPCs via the NF‑κB pathway, thus suggesting that SDF‑1/CXCR signaling may be a therapeutic target for the treatment of degenerative IVD diseases. PMID:27220474

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-09-01

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

  2. [Transport of newly synthesized rRNA from the nucleus to the cytoplasm in freely suspended cells of parsley (Petroselinum sativum)].

    Science.gov (United States)

    Seitz, U; Seitz, U

    1972-06-01

    A rapidly labelled rRNA precursor can be detected in callus cells of Petroselinum sativum grown on a liquid synthetic medium. Its molecular weight has been calculated to be 2.3×10(6). This value agrees with that of the rRNA precursor from other plant material. In order to follow the synthesis and processing of rRNA in time and to correlate single steps in this process with cell organelles it was necessary to obtain pure fractions of nuclei and ribosomes. The isolation method for nuclei is given in detail. The nucleic acids are separated on polyacrylamide gels of low acrylamide concentration. Pulse-chase experiments show that the rRNA precursor is split into two fragments within the nucleus: an 18S and a 25S component. The 18S RNA leaves the nucleus rapidly. It is already found quantitatively in the ribosomal fraction after 30-60 min chase. At that time the 25S RNA is still within the nucleus; it appears much later in the ribosomes. Since the increase in ribosomal label occurs simultaneously with the decrease in nuclear label, it is concluded that there is no degradation of 18S RNA within the nucleus. Apparently there are two distinct transport mechanisms with different kinetics for the two RNA components. PMID:24477955

  3. Membrane-to-nucleus signaling links insulin-like growth factor-1- and stem cell factor-activated pathways.

    Directory of Open Access Journals (Sweden)

    Yujiro Hayashi

    Full Text Available Stem cell factor (mouse: Kitl, human: KITLG and insulin-like growth factor-1 (IGF1, acting via KIT and IGF1 receptor (IGF1R, respectively, are critical for the development and integrity of several tissues. Autocrine/paracrine KITLG-KIT and IGF1-IGF1R signaling are also activated in several cancers including gastrointestinal stromal tumors (GIST, the most common sarcoma. In murine gastric muscles, IGF1 promotes Kitl-dependent development of interstitial cells of Cajal (ICC, the non-neoplastic counterpart of GIST, suggesting cooperation between these pathways. Here, we report a novel mechanism linking IGF1-IGF1R and KITLG-KIT signaling in both normal and neoplastic cells. In murine gastric muscles, the microenvironment for ICC and GIST, human hepatic stellate cells (LX-2, a model for cancer niches, and GIST cells, IGF1 stimulated Kitl/KITLG protein and mRNA expression and promoter activity by activating several signaling pathways including AKT-mediated glycogen synthase kinase-3β inhibition (GSK3i. GSK3i alone also stimulated Kitl/KITLG expression without activating mitogenic pathways. Both IGF1 and GSK3i induced chromatin-level changes favoring transcriptional activation at the Kitl promoter including increased histone H3/H4 acetylation and H3 lysine (K 4 methylation, reduced H3K9 and H3K27 methylation and reduced occupancy by the H3K27 methyltransferase EZH2. By pharmacological or RNA interference-mediated inhibition of chromatin modifiers we demonstrated that these changes have the predicted impact on KITLG expression. KITLG knock-down and immunoneutralization inhibited the proliferation of GIST cells expressing wild-type KIT, signifying oncogenic autocrine/paracrine KITLG-KIT signaling. We conclude that membrane-to-nucleus signaling involving GSK3i establishes a previously unrecognized link between the IGF1-IGF1R and KITLG-KIT pathways, which is active in both physiologic and oncogenic contexts and can be exploited for therapeutic purposes.

  4. Membrane-to-nucleus signaling links insulin-like growth factor-1- and stem cell factor-activated pathways.

    Science.gov (United States)

    Hayashi, Yujiro; Asuzu, David T; Gibbons, Simon J; Aarsvold, Kirsten H; Bardsley, Michael R; Lomberk, Gwen A; Mathison, Angela J; Kendrick, Michael L; Shen, K Robert; Taguchi, Takahiro; Gupta, Anu; Rubin, Brian P; Fletcher, Jonathan A; Farrugia, Gianrico; Urrutia, Raul A; Ordog, Tamas

    2013-01-01

    Stem cell factor (mouse: Kitl, human: KITLG) and insulin-like growth factor-1 (IGF1), acting via KIT and IGF1 receptor (IGF1R), respectively, are critical for the development and integrity of several tissues. Autocrine/paracrine KITLG-KIT and IGF1-IGF1R signaling are also activated in several cancers including gastrointestinal stromal tumors (GIST), the most common sarcoma. In murine gastric muscles, IGF1 promotes Kitl-dependent development of interstitial cells of Cajal (ICC), the non-neoplastic counterpart of GIST, suggesting cooperation between these pathways. Here, we report a novel mechanism linking IGF1-IGF1R and KITLG-KIT signaling in both normal and neoplastic cells. In murine gastric muscles, the microenvironment for ICC and GIST, human hepatic stellate cells (LX-2), a model for cancer niches, and GIST cells, IGF1 stimulated Kitl/KITLG protein and mRNA expression and promoter activity by activating several signaling pathways including AKT-mediated glycogen synthase kinase-3β inhibition (GSK3i). GSK3i alone also stimulated Kitl/KITLG expression without activating mitogenic pathways. Both IGF1 and GSK3i induced chromatin-level changes favoring transcriptional activation at the Kitl promoter including increased histone H3/H4 acetylation and H3 lysine (K) 4 methylation, reduced H3K9 and H3K27 methylation and reduced occupancy by the H3K27 methyltransferase EZH2. By pharmacological or RNA interference-mediated inhibition of chromatin modifiers we demonstrated that these changes have the predicted impact on KITLG expression. KITLG knock-down and immunoneutralization inhibited the proliferation of GIST cells expressing wild-type KIT, signifying oncogenic autocrine/paracrine KITLG-KIT signaling. We conclude that membrane-to-nucleus signaling involving GSK3i establishes a previously unrecognized link between the IGF1-IGF1R and KITLG-KIT pathways, which is active in both physiologic and oncogenic contexts and can be exploited for therapeutic purposes. PMID:24116170

  5. Effect of microRNA-21 on the proliferation of human degenerated nucleus pulposus by targeting programmed cell death 4

    Directory of Open Access Journals (Sweden)

    B. Chen

    2016-01-01

    Full Text Available This study aims to explore the effect of microRNA-21 (miR-21 on the proliferation of human degenerated nucleus pulposus (NP by targeting programmed cell death 4 (PDCD4 tumor suppressor. NP tissues were collected from 20 intervertebral disc degeneration (IDD patients, and from 5 patients with traumatic spine fracture. MiR-21 expressions were tested. NP cells from IDD patients were collected and divided into blank control group, negative control group (transfected with miR-21 negative sequences, miR-21 inhibitor group (transfected with miR-21 inhibitors, miR-21 mimics group (transfected with miR-21 mimics and PDCD4 siRNA group (transfected with PDCD4 siRNAs. Cell growth was estimated by Cell Counting Kit-8; PDCD4, MMP-2,MMP-9 mRNA expressions were evaluated by qRT-PCR; PDCD4, c-Jun and p-c-Jun expressions were tested using western blot. In IDD patients, the expressions of miR-21 and PDCD4 mRNA were respectively elevated and decreased (both P<0.05. The miR-21 expressions were positively correlated with Pfirrmann grades, but negatively correlated with PDCD4 mRNA (both P<0.001. In miR-21 inhibitor group, cell growth, MMP-2 and MMP-9 mRNA expressions, and p-c-Jun protein expressions were significantly lower, while PDCD4 mRNA and protein expressions were higher than the other groups (all P<0.05. These expressions in the PDCD4 siRNA and miR-21 mimics groups was inverted compared to that in the miR-21 inhibitor group (all P<0.05. MiR-21 could promote the proliferation of human degenerated NP cells by targeting PDCD4, increasing phosphorylation of c-Jun protein, and activating AP-1-dependent transcription of MMPs, indicating that miR-21 may be a crucial biomarker in the pathogenesis of IDD.

  6. Reversal of morphine-induced cell-type-specific synaptic plasticity in the nucleus accumbens shell blocks reinstatement.

    Science.gov (United States)

    Hearing, Matthew C; Jedynak, Jakub; Ebner, Stephanie R; Ingebretson, Anna; Asp, Anders J; Fischer, Rachel A; Schmidt, Clare; Larson, Erin B; Thomas, Mark John

    2016-01-19

    Drug-evoked plasticity at excitatory synapses on medium spiny neurons (MSNs) of the nucleus accumbens (NAc) drives behavioral adaptations in addiction. MSNs expressing dopamine D1 (D1R-MSN) vs. D2 receptors (D2R-MSN) can exert antagonistic effects in drug-related behaviors, and display distinct alterations in glutamate signaling following repeated exposure to psychostimulants; however, little is known of cell-type-specific plasticity induced by opiates. Here, we find that repeated morphine potentiates excitatory transmission and increases GluA2-lacking AMPA receptor expression in D1R-MSNs, while reducing signaling in D2-MSNs following 10-14 d of forced abstinence. In vivo reversal of this pathophysiology with optogenetic stimulation of infralimbic cortex-accumbens shell (ILC-NAc shell) inputs or treatment with the antibiotic, ceftriaxone, blocked reinstatement of morphine-evoked conditioned place preference. These findings confirm the presence of overlapping and distinct plasticity produced by classes of abused drugs within subpopulations of MSNs that may provide targetable molecular mechanisms for future pharmacotherapies. PMID:26739562

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-01-20

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

  8. Cell Biological Mechanisms of Activity-Dependent Synapse to Nucleus Translocation of CRTC1 in Neurons

    Directory of Open Access Journals (Sweden)

    Toh Hean eCh'ng

    2015-09-01

    Full Text Available Previous studies have revealed a critical role for CREB-regulated transcriptional coactivator (CRTC1 in regulating neuronal gene expression during learning and memory. CRTC1 localizes to synapses but undergoes activity-dependent nuclear translocation to regulate the transcription of CREB target genes. Here we investigate the long-distance retrograde transport of CRTC1 in hippocampal neurons. We show that local elevations in calcium, triggered by activation of synaptic glutamate receptors and L-type voltage-gated calcium channels, initiate active, dynein-mediated retrograde transport of CRTC1 along microtubules. We identify a nuclear localization signal within CRTC1, and characterize three conserved serine residues whose dephosphorylation is required for nuclear import. Domain analysis reveals that the amino-terminal third of CRTC1 contains all of the signals required for regulated nucleocytoplasmic trafficking. We fuse this region to Dendra2 to generate a reporter construct and perform live-cell imaging coupled with local uncaging of glutamate and photoconversion to characterize the dynamics of stimulus-induced retrograde transport and nuclear accumulation.

  9. Cell biological mechanisms of activity-dependent synapse to nucleus translocation of CRTC1 in neurons

    Science.gov (United States)

    Ch'ng, Toh Hean; DeSalvo, Martina; Lin, Peter; Vashisht, Ajay; Wohlschlegel, James A.; Martin, Kelsey C.

    2015-01-01

    Previous studies have revealed a critical role for CREB-regulated transcriptional coactivator (CRTC1) in regulating neuronal gene expression during learning and memory. CRTC1 localizes to synapses but undergoes activity-dependent nuclear translocation to regulate the transcription of CREB target genes. Here we investigate the long-distance retrograde transport of CRTC1 in hippocampal neurons. We show that local elevations in calcium, triggered by activation of glutamate receptors and L-type voltage-gated calcium channels, initiate active, dynein-mediated retrograde transport of CRTC1 along microtubules. We identify a nuclear localization signal within CRTC1, and characterize three conserved serine residues whose dephosphorylation is required for nuclear import. Domain analysis reveals that the amino-terminal third of CRTC1 contains all of the signals required for regulated nucleocytoplasmic trafficking. We fuse this region to Dendra2 to generate a reporter construct and perform live-cell imaging coupled with local uncaging of glutamate and photoconversion to characterize the dynamics of stimulus-induced retrograde transport and nuclear accumulation. PMID:26388727

  10. Temporal coding by cochlear nucleus bushy cells in DBA/2J mice with early onset hearing loss.

    Science.gov (United States)

    Wang, Yong; Manis, Paul B

    2006-12-01

    The bushy cells of the anterior ventral cochlear nucleus (AVCN) preserve or improve the temporal coding of sound information arriving from auditory nerve fibers (ANF). The critical cellular mechanisms entailed in this process include the specialized nerve terminals, the endbulbs of Held, and the membrane conductance configuration of the bushy cell. In one strain of mice (DBA/2J), an early-onset hearing loss can cause a reduction in neurotransmitter release probability, and a smaller and slower spontaneous miniature excitatory postsynaptic current (EPSC) at the endbulb synapse. In the present study, by using a brain slice preparation, we tested the hypothesis that these changes in synaptic transmission would degrade the transmission of timing information from the ANF to the AVCN bushy neuron. We show that the electrical excitability of bushy cells in hearing-impaired old DBA mice was different from that in young, normal-hearing DBA mice. We found an increase in the action potential (AP) firing threshold with current injection; a larger AP afterhyperpolarization; and an increase in the number of spikes produced by large depolarizing currents. We also tested the temporal precision of bushy cell responses to high-frequency stimulation of the ANF. The standard deviation of spikes (spike jitter) produced by ANF-evoked excitatory postsynaptic potentials (EPSPs) was largely unaffected in old DBA mice. However, spike entrainment during a 100-Hz volley of EPSPs was significantly reduced. This was not a limitation of the ability of bushy cells to fire APs at this stimulus frequency, because entrainment to trains of current pulses was unaffected. Moreover, the decrease in entrainment is not attributable to increased synaptic depression. Surprisingly, the spike latency was 0.46 ms shorter in old DBA mice, and was apparently attributable to a faster conduction velocity, since the evoked excitatory postsynaptic current (EPSC) latency was shorter in old DBA mice as well. We also

  11. IFT88 plays a cilia- and PCP-independent role in controlling oriented cell divisions during vertebrate embryonic development.

    Science.gov (United States)

    Borovina, Antonia; Ciruna, Brian

    2013-10-17

    The role for cilia in establishing planar cell polarity (PCP) is contentious. Although knockdown of genes known to function in ciliogenesis has been reported to cause PCP-related morphogenesis defects in zebrafish, genetic mutations affecting intraflagellar transport (IFT) do not show PCP phenotypes despite the requirement for IFT in cilia formation. This discrepancy has been attributed to off-target effects of antisense morpholino oligonucleotide (MO) injection, confounding maternal effects in zygotic mutant embryos, or an inability to distinguish between cilia-dependent versus cilia-independent protein functions. To determine the role of cilia in PCP, we generated maternal + zygotic IFT88 (MZift88) mutant zebrafish embryos, which never form cilia. We clearly demonstrate that cilia are not required to establish PCP. Rather, IFT88 plays a cilia-independent role in controlling oriented cell divisions at gastrulation and neurulation. Our results have important implications for the interpretation of cilia gene function in normal development and in disease.

  12. DNA damage in stem cells activates p21, inhibits p53, and induces symmetric self-renewing divisions.

    Science.gov (United States)

    Insinga, Alessandra; Cicalese, Angelo; Faretta, Mario; Gallo, Barbara; Albano, Luisa; Ronzoni, Simona; Furia, Laura; Viale, Andrea; Pelicci, Pier Giuseppe

    2013-03-01

    DNA damage leads to a halt in proliferation owing to apoptosis or senescence, which prevents transmission of DNA alterations. This cellular response depends on the tumor suppressor p53 and functions as a powerful barrier to tumor development. Adult stem cells are resistant to DNA damage-induced apoptosis or senescence, however, and how they execute this response and suppress tumorigenesis is unknown. We show that irradiation of hematopoietic and mammary stem cells up-regulates the cell cycle inhibitor p21, a known target of p53, which prevents p53 activation and inhibits p53 basal activity, impeding apoptosis and leading to cell cycle entry and symmetric self-renewing divisions. p21 also activates DNA repair, limiting DNA damage accumulation and self-renewal exhaustion. Stem cells with moderate DNA damage and diminished self-renewal persist after irradiation, however. These findings suggest that stem cells have evolved a unique, p21-dependent response to DNA damage that leads to their immediate expansion and limits their long-term survival.

  13. The influence of the slowing of Earth's rotation: A hypothesis to explain cell division synchrony under different day duration in earlier and later evolved unicellular algae

    Science.gov (United States)

    Costas, E.; González-Gil, S.; López-Rodas, V.; Aguilera, A.

    1996-03-01

    Every year the Earth's rotation period is reduced, mainly due to the tidal drag of the moon. The length of day increases continuously by about 1 h every 200 million years. The period of rotation around the Sun remains constant; hence, the length of the year remains constant, so years acquire progressively fewer days. Many unicellular algae show rhythmicity in their cell division cycle. If primitive algae evolved under a shorter day duration, then it is possible that the early-evolved algae had to synchronize their cell division cycle to shorter lengths of day than did later-evolved algae. We tested this hypothesis by growing Cyanobacteria, Dinophyceae, Prasinophyceae, Bacillariophyceae and Conjugatophyceae (evolutionary appearance probably in this order) at 8∶8 h light-dark cycles (LD), 10∶10 LD, and 12∶12 LD, at 20 or 27°C. Cyanobacteria synchronized their cell division cycles optimally at 8∶8 h LD, Dinophyceae and Prasinophyceae at 10∶10 h LD, and Conjugatophyceae and Bacillariophyceae at 12∶12 h LD. The synchrony of cell division was scarcely affected by temperature. Results suggested that the early evolved unicellular autotrophic organisms such as the Cyanobacteria synchronized their cell division cycle under a shorter day duration than later-evolved unicellular algae, and these traits may have been conserved by quiescent genes up to the present day.

  14. A gibberellin-induced nuclease is localized in the nucleus of wheat aleurone cells undergoing programmed cell death

    OpenAIRE

    Domínguez, Fernándo; Moreno Onorato, Francisco Javier; Cejudo Fernández, Francisco Javier

    2003-01-01

    The aleurone layer of cereal grains undergoes a gibberellin-regulated process of programmed cell death (PCD) following germination. We have applied a combination of ultrastructural and biochemical approaches to analyze aleurone PCD in intact wheat grains. The terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay revealed that PCD was initiated in aleurone cells proximal to the embryo and then extended to distal cells. DNA fragmentation and terminal deoxynucleotidyl trans...

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

    Directory of Open Access Journals (Sweden)

    Tolliday Nicola J

    2006-06-01

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

  16. Lyme disease and relapsing fever Borrelia elongate through zones of peptidoglycan synthesis that mark division sites of daughter cells.

    Science.gov (United States)

    Jutras, Brandon Lyon; Scott, Molly; Parry, Bradley; Biboy, Jacob; Gray, Joe; Vollmer, Waldemar; Jacobs-Wagner, Christine

    2016-08-16

    Agents that cause Lyme disease, relapsing fever, leptospirosis, and syphilis belong to the phylum Spirochaetae-a unique lineage of bacteria most known for their long, spiral morphology. Despite the relevance to human health, little is known about the most fundamental aspects of spirochete growth. Here, using quantitative microscopy to track peptidoglycan cell-wall synthesis, we found that the Lyme disease spirochete Borrelia burgdorferi displays a complex pattern of growth. B. burgdorferi elongates from discrete zones that are both spatially and temporally regulated. In addition, some peptidoglycan incorporation occurs along the cell body, with the notable exception of a large region at the poles. Newborn cells inherit a highly active zone of peptidoglycan synthesis at midcell that contributes to elongation for most of the cell cycle. Concomitant with the initiation of nucleoid separation and cell constriction, second and third zones of elongation are established at the 1/4 and 3/4 cellular positions, marking future sites of division for the subsequent generation. Positioning of elongation zones along the cell is robust to cell length variations and is relatively precise over long distances (>30 µm), suggesting that cells ‟sense" relative, as opposed to absolute, cell length to establish zones of peptidoglycan synthesis. The transition from one to three zones of peptidoglycan growth during the cell cycle is also observed in relapsing fever Borrelia. However, this mode of growth does not extend to representative species from other spirochetal genera, suggesting that this distinctive growth mode represents an evolutionary divide in the spirochete phylum. PMID:27506799

  17. From Meiosis to Mitosis: The Astonishing Flexibility of Cell Division Mechanisms in Early Mammalian Development.

    Science.gov (United States)

    Bury, L; Coelho, P A; Glover, D M

    2016-01-01

    The execution of female meiosis and the establishment of the zygote is arguably the most critical stage of mammalian development. The egg can be arrested in the prophase of meiosis I for decades, and when it is activated, the spindle is assembled de novo. This spindle must function with the highest of fidelity and yet its assembly is unusually achieved in the absence of conventional centrosomes and with minimal influence of chromatin. Moreover, its dramatic asymmetric positioning is achieved through remarkable properties of the actin cytoskeleton to ensure elimination of the polar bodies. The second meiotic arrest marks a uniquely prolonged metaphase eventually interrupted by egg activation at fertilization to complete meiosis and mark a period of preparation of the male and female pronuclear genomes not only for their entry into the mitotic cleavage divisions but also for the imminent prospect of their zygotic expression. PMID:27475851

  18. Efficient Subcellular Targeting to the Cell Nucleus of Quantum Dots Densely Decorated with a Nuclear Localization Sequence Peptide.

    Science.gov (United States)

    Maity, Amit Ranjan; Stepensky, David

    2016-01-27

    Organelle-targeted drug delivery can enhance the efficiency of the intracellularly acting drugs and reduce their toxicity. We generated core-shell type CdSe-ZnS quantum dots (QDs) densely decorated with NLS peptidic targeting residues using a 3-stage decoration approach and investigated their endocytosis and nuclear targeting efficiencies. The diameter of the generated QDs increased following the individual decoration stages (16.3, 18.9, and 21.9 nm), the ζ-potential became less negative (-33.2, -17.5, and -11.9 mV), and characteristic changes appeared in the FTIR spectra following decoration with the linker and NLS peptides. Quantitative analysis of the last decoration stage revealed that 37.9% and 33.2% of the alkyne-modified NLS groups that were added to the reaction mix became covalently attached or adsorbed to the QDs surface, respectively. These numbers correspond to 63.6 and 55.7 peptides conjugated or adsorbed to a single QD (the surface density of 42 and 37 conjugated and adsorbed peptides per 1000 nm(2) of the QDs surface), which is higher than in the majority of previous studies that reported decoration efficiencies of formulations intended for nuclear-targeted drug delivery. QDs decorated with NLS peptides undergo more efficient endocytosis, as compared to other investigated QDs formulations, and accumulated to a higher extent in the cell nucleus or in close vicinity to it (11.9%, 14.6%, and 56.1% of the QDs endocytosed by an average cell for the QD-COOH, QD-azide, and QD-NLS formulations, respectively). We conclude that dense decoration of QDs with NLS residues increased their endocytosis and led to their nuclear targeting (preferential accumulation in the cells nuclei or in close vicinity to them). The experimental system and research tools that were used in this study allow quantitative investigation of the mechanisms that govern the QDs nuclear targeting and their dependence on the formulation properties. These findings will contribute to the

  19. Knockdown of dystrophin Dp71 impairs PC12 cells cycle: localization in the spindle and cytokinesis structures implies a role for Dp71 in cell division.

    Directory of Open Access Journals (Sweden)

    Marcela Villarreal-Silva

    Full Text Available The function of dystrophin Dp71 in neuronal cells remains to be established. Previously, we revealed the involvement of this protein in both nerve growth factor (NGF-induced neuronal differentiation and cell adhesion by isolation and characterization of PC12 neuronal cells with depleted levels of Dp71. In this work, a novel phenotype of Dp71-knockdown cells was characterized, which is their delayed growth rate. Cell cycle analyses revealed an altered behavior of Dp71-depleted cells, which consists of a delay in G0/G1 transition and an increase in apoptosis during nocodazole-induced mitotic arrest. Dp71 associates with lamin B1 and β-dystroglycan, proteins involved in aspects of the cell division cycle; therefore, we compared the distribution of Dp71 with that of lamin B1 and β-dystroglycan in PC12 cells at mitosis and cytokinesis by means of immunofluorescence and confocal microscopy analysis. All of these three proteins exhibited a similar immunostaining pattern, localized at mitotic spindle, cleavage furrow, and midbody. It is noteworthy that a drastic decreased staining in mitotic spindle, cleavage furrow, and midbody was observed for both lamin B1 and β-dystroglycan in Dp71-depleted cells. Furthermore, we demonstrated the interaction of Dp71 with lamin B1 in PC12 cells by immunoprecipitation and pull-down assays, and importantly, we revealed that knockdown of Dp71 expression caused a marked reduction in lamin B1 levels and altered localization of the nuclear envelope protein emerin. Our data indicate that Dp71 is a component of the mitotic spindle and cytokinesis multi-protein apparatuses that might modulate the cell division cycle by affecting lamin B1 and β-dystroglycan levels.

  20. Enteral peptide formulas inhibit radiation induced enteritis and apoptosis in intestinal epithelial cells and suppress the expression and function of Alzheimer's and cell division control gene products

    International Nuclear Information System (INIS)

    Studies have shown that patients receiving enteral peptide formulas prior to irradiation have a significantly reduced incidence of enteritis and express a profound increase in intestinal cellularity. Two conceptual approaches were taken to describe this response. First was the evaluation in changes in programmed intestinal cell death and secondly the evaluation of a gene product controlling cell division cycling. This study provided a relationship between the ratio of cell death to cell formulations. The results indicate that in the canine and murine models, irradiation induces expression of the Alzheimer's gene in intestinal crypt cells, while the incidence of apoptosis in apical cells is significantly increased. The use of peptide enteral formulations suppresses the expression of the Alzheimer's gene in crypt cells, while apoptosis is eliminated in the apical cells of the intestine. Concomitantly, enteral peptide formulations suppress the function of the CK-II gene product in the basal and baso-lateral cells of the intestine. These data indicate that although the mitotic index is significantly reduced in enterocytes, this phenomenon alone is not sufficient to account for the peptide-induced radio-resistance of the intestine. The data also indicate a significant reduction of normal apoptosis in the upper lateral and apical cells of the intestinal villi. Thus, the ratio of cell death to cell replacement is significantly decreased resulting in an increase in villus height and hypertrophy of the apical villus cells. Thus, peptide solutions should be considered as an adjunct treatment both in radio- and chemotherapy

  1. Cell division in the unicellular microalga Dunaliella viridis depends on phosphorylation of extracellular signal-regulated kinases (ERKs).

    Science.gov (United States)

    Jiménez, Carlos; Cossío, Belén R; Rivard, Christopher J; Berl, Tomás; Capasso, Juan M

    2007-01-01

    In mammalian cells, MAPKs are involved in both stress response (JNK and p38 pathways) and cell proliferation and differentiation [extracellular signal-regulated kinase (ERK)] through protein kinase cascades. Exposure of Dunaliella viridis cell cultures to PD98059, a very specific inhibitor of the ERK signalling pathway, resulted in a total arrest of cell proliferation and a complete dephosphorylation of ERK. As shown by flow cytometry analysis of propidium iodide-stained cells, PD98059 stopped mitosis at the G(2) phase after the S phase has been completed. Multiple physiological parameters such as cell motility and reducing power generation (NADPH) clearly indicate that the treated cells are wholly viable. Exposure of D. viridis to environmental stresses that impair cell division, such as hyperosmotic shock, nitrogen starvation, or sublethal UV irradiation, caused a marked decrease in the phospho-ERK levels as detected by western blot. Two 400 bp polynucleotides from D. viridis with high homologies to published sequences of ERK1 and ERK2 were cloned, sequenced, and submitted to GenBank. Northern blot analysis revealed two mRNA bands of approximately 1.9 kb, consistent with the expected size of ERK proteins ( approximately 40 kDa). Sequence analysis showed that they contained several mitogen-activated protein kinase (MAPK) conserved domains, including II, III, VIb, VII, and the double phosphorylation motif. Interestingly, in D. viridis, this motif was T*DY* instead of the canonic T*EY*. Based on this finding, ERK plant sequences can be divided into two groups, one termed the T*DY* branch and the other termed the T*EY* branch. The molecular and functional data presented here suggest that ERK is a very ancient signalling pathway and that it was already present in the last common ancestor of all eukaryotic cells. PMID:17220513

  2. Construction of a tissue engineered intervertebral disc with high biological activity using an allogeneic intervertebral disc supplemented with transfected nucleus pulposus cells expressing exogenous dopamine beta-hydroxylase.

    Science.gov (United States)

    Bai, M; Wang, Y H; Yin, H P; Li, S W

    2015-09-09

    This study addressed the in vitro construction and biological activity of tissue engineered intervertebral discs with exogenous human dopamine beta-hydroxylase (DBH) nucleus pulposus cells. pSNAV2.0-DBH expression plasmids were utilized to enhance the survival rates of intervertebral disc tissue cells. Various concentrations of transfected nucleus pulposus cells were injected into the discs, and DBH mRNA expression was determined using polymerase chain reaction amplification. Polysaccharide content and total collagen protein content in the engineered disc nucleus pulposus tissue were determined. The visible fluorescence intensities of the 1 x 10(5) and 1 x 10(6) groups vs the 1 x 10(4) group were significantly increased (P 0.05) at 7 days after injection. DBH mRNA expression could be detected in the all but the EGFP control group at 14 days culture. No significant difference was observed in the protein content between the 1 x 10(4) and the control groups at various times, while the protein content was significantly higher in the 1 x 10(5) vs the control and the 1 x 10(4) groups at 7-, 14-, and 21-day cultures. These results demonstrate that a tissue engineered intervertebral disc with high biological activity can be constructed by utilizing allogeneic intervertebral discs stored in liquid nitrogen and a 1 x 10(5) transfected nucleus pulposus cell complex with in vitro culture for 14 days. This model can be used in animal experiments to study the biological activity of the engineered discs.

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

    Directory of Open Access Journals (Sweden)

    Lisa M Nigro

    2016-08-01

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

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

    DEFF Research Database (Denmark)

    Jensen, Rasmus Bugge

    2006-01-01

    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...

  5. Dynamic FtsA and FtsZ localization and outer membrane alterations during polar growth and cell division in Agrobacterium tumefaciens

    OpenAIRE

    Zupan, John R.; Cameron, Todd A.; Anderson-Furgeson, James; Zambryski, Patricia C.

    2013-01-01

    Growth and cell division in rod-shaped bacteria have been primarily studied in species that grow predominantly by peptidoglycan (PG) synthesis along the length of the cell. Rhizobiales species, however, predominantly grow by PG synthesis at a single pole. Here we characterize the dynamic localization of several Agrobacterium tumefaciens components during the cell cycle. First, the lipophilic dye FM 4-64 predominantly stains the outer membranes of old poles versus growing poles. In cells about...

  6. The WD40 repeat protein NEDD1 functions in microtubule organization during cell division in Arabidopsis thaliana.

    Science.gov (United States)

    Zeng, C J Tracy; Lee, Y-R Julie; Liu, Bo

    2009-04-01

    Although cells of flowering plants lack a structurally defined microtubule-organizing center like the centrosome, organization of the spindles and phragmoplasts in mitosis is known to involve the evolutionarily conserved gamma-tubulin complex. We have investigated the function of Arabidopsis thaliana NEDD1, a WD40 repeat protein related to the animal NEDD1/GCP-WD protein, which interacts with the gamma-tubulin complex. The NEDD1 protein decorates spindle microtubules (MTs) preferentially toward spindle poles and phragmoplast MTs toward their minus ends. A T-DNA insertional allele of the single NEDD1 gene was isolated and maintained in heterozygous sporophytes, and NEDD1's function in cell division was analyzed in haploid microspores produced by the heterozygote. In approximately half of the dividing microspores exhibiting aberrant MT organization, spindles were no longer restricted to the cell periphery and became abnormally elongated. After mitosis, MTs aggregated between reforming nuclei but failed to appear in a bipolar configuration. Consequently, defective microspores did not form a continuous cell plate, and two identical nuclei were produced with no differentiation into generative and vegetative cells. Our results support the notion that the plant NEDD1 homolog plays a critical role in MT organization during mitosis, and its function is likely linked to that of the gamma-tubulin complex. PMID:19383896

  7. The cyanobacterial cell division factor Ftn6 contains an N-terminal DnaD-like domain

    Directory of Open Access Journals (Sweden)

    Saguez Cyril

    2009-08-01

    Full Text Available Abstract Background DNA replication and cell cycle as well as their relationship have been extensively studied in the two model organisms E. coli and B. subtilis. By contrast, little is known about these processes in cyanobacteria, even though they are crucial to the biosphere, in utilizing solar energy to renew the oxygenic atmosphere and in producing the biomass for the food chain. Recent studies have allowed the identification of several cell division factors that are specifics to cyanobacteria. Among them, Ftn6 has been proposed to function in the recruitment of the crucial FtsZ proteins to the septum or the subsequent Z-ring assembly and possibly in chromosome segregation. Results In this study, we identified an as yet undescribed domain located in the conserved N-terminal region of Ftn6. This 77 amino-acids-long domain, designated here as FND (Ftn6 N-Terminal Domain, exhibits striking sequence and structural similarities with the DNA-interacting module, listed in the PFAM database as the DnaD-like domain (pfam04271. We took advantage of the sequence similarities between FND and the DnaD-like domains to construct a homology 3D-model of the Ftn6 FND domain from the model cyanobacterium Synechocystis PCC6803. Mapping of the conserved residues exposed onto the FND surface allowed us to identify a highly conserved area that could be engaged in Ftn6-specific interactions. Conclusion Overall, similarities between FND and DnaD-like domains as well as previously reported observations on Ftn6 suggest that FND may function as a DNA-interacting module thereby providing an as yet missing link between DNA replication and cell division in cyanobacteria. Consistently, we also showed that Ftn6 is involved in tolerance to DNA damages generated by UV rays.

  8. Spindle formation and microtubule organization during first division in reconstructed rat embryos produced by somatic cell nuclear transfer.

    Science.gov (United States)

    Tomioka, Ikuo; Mizutani, Eiji; Yoshida, Tomoyuki; Sugawara, Atsushi; Inai, Kentaro; Sasada, Hiroshi; Sato, Eimei

    2007-08-01

    The present study was conducted to demonstrate the spindle formation and behavior of chromosomes and microtubules during first division in reconstructed rat embryos produced by somatic cell nuclear transfer (SCNT) with cumulus cell nuclei. To demonstrate the effect of oocyte aging after ovulation on the cleavage of SCNT embryos, micromanipulation was carried out 11, 15 and 18 h after injection of hCG. SCNT oocytes were activated by incubation in culture medium supplemented with 5 microM ionomycin for 5 min followed by treatment with 2 mM 6-dimethylaminopurine (6-DMAP) in mR1ECM for 2-3 h. For immunocytochemical observation, the SCNT embryos were incubated with monoclonal anti-alpha-tubulin antibody and then fluorescein isothiocyanate (FITC)-conjugated goat anti-mouse IgG. Cleavage rates were significantly higher for oocytes collected after 15 and 18 h rather than for those collected 11 h after injection of hCG (56 and 53%, respectively vs. 28%; P<0.05). Premature chromosome condensation occurred before activation of the SCNT oocytes, but adequate spindle formation was only rarely observed. The distribution of microtubules in SCNT embryos after activation was different from those of fertilized and parthenogenic oocytes, i.e., a dense microtubule organization shaped like a ring was observed. Eighteen to 20 h post-activation, most SCNT embryos were in the 2-cell stage, but no nucleoli were clearly visible, which was quite different from the fertilized oocytes. In addition, first division with and without small cellular bodies containing DNA was observed in the rat SCNT embryos in some cases. The present study suggests that reorganization of transferred nuclei in rat SCNT embryos may be inadequate in terms of formation of the mitotic assembly and nucleolar reorganization. PMID:17446658

  9. The Garlic Allelochemical Diallyl Disulfide Affects Tomato Root Growth by Influencing Cell Division, Phytohormone Balance and Expansin Gene Expression.

    Science.gov (United States)

    Cheng, Fang; Cheng, Zhihui; Meng, Huanwen; Tang, Xiangwei

    2016-01-01

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

  10. The Garlic Allelochemical Diallyl Disulfide Affects Tomato Root Growth by Influencing Cell Division, Phytohormone Balance and Expansin Gene Expression

    Science.gov (United States)

    Cheng, Fang; Cheng, Zhihui; Meng, Huanwen; Tang, Xiangwei

    2016-01-01

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

  11. Neurons of human nucleus accumbens

    Directory of Open Access Journals (Sweden)

    Sazdanović Maja

    2011-01-01

    Full Text Available Background/Aim. Nucleus accumbens is a part of the ventral striatum also known as a drug active brain region, especially related with drug addiction. The aim of the study was to investigate the Golgi morphology of the nucleus accumbens neurons. Methods. The study was performed on the frontal and sagittal sections of 15 human brains by the Golgi Kopsch method. We classified neurons in the human nucleus accumbens according to their morphology and size into four types: type I - fusiform neurons; type II - fusiform neurons with lateral dendrite, arising from a part of the cell body; type III - pyramidal-like neuron; type IV - multipolar neuron. The medium spiny neurons, which are mostly noted regarding to the drug addictive conditions of the brain, correspond to the type IV - multipolar neurons. Results. Two regions of human nucleus accumbens could be clearly recognized on Nissl and Golgi preparations each containing different predominant neuronal types. Central part of nucleus accumbens, core region, has a low density of impregnated neurons with predominant type III, pyramidal-like neurons, with spines on secondary branches and rare type IV, multipolar neurons. Contrary to the core, peripheral region, shell of nucleus, has a high density of impregnated neurons predominantly contained of type I and type IV - multipolar neurons, which all are rich in spines on secondary and tertiary dendritic branches. Conclusion. Our results indicate great morphological variability of human nucleus accumbens neurons. This requires further investigations and clarifying clinical significance of this important brain region.

  12. Low-concentration uranium enters the HepG2 cell nucleus rapidly and induces cell stress response.

    Science.gov (United States)

    Guéguen, Yann; Suhard, David; Poisson, Clémentine; Manens, Line; Elie, Christelle; Landon, Géraldine; Bouvier-Capely, Céline; Rouas, Caroline; Benderitter, Marc; Tessier, Christine

    2015-12-25

    This study aimed to compare the cell stress effects of low and high uranium concentrations and relate them to its localization, precipitate formation, and exposure time. The time-course analysis shows that uranium appears in cell nuclei as a soluble form within 5 min of exposure, and quickly induces expression of antioxidant and DNA repair genes. On the other hand, precipitate formations began at the very beginning of exposure at the 300-μM concentration, but took longer to appear at lower concentrations. Adaptive response might occur at low concentrations but are overwhelmed at high concentrations, especially when uranium precipitates are abundant.

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

    International Nuclear Information System (INIS)

    Highlights: •Metals induce morphological alterations on P. subcapitata. •Algal cell cycle consists: mother cell growth; cell division, with two nucleus divisions; release of four autospores. •Cu(II) and Cr(VI) arrest cell growth before the first nuclear division. •Cd(II) arrests cell growth after the second nuclear division but before the cytokinesis. •The approach used can be useful in the elucidation of different modes of action of pollutants. -- Abstract: The impact of metals (Cd, Cr, Cu and Zn) on growth, cell volume and cell division of the freshwater alga Pseudokirchneriella subcapitata exposed over a period of 72 h was investigated. The algal cells were exposed to three nominal concentrations of each metal: low (closed to 72 h-EC10 values), intermediate (closed to 72 h-EC50 values) and high (upper than 72 h-EC90 values). The exposure to low metal concentrations resulted in a decrease of cell volume. On the contrary, for the highest metal concentrations an increase of cell volume was observed; this effect was particularly notorious for Cd and less pronounced for Zn. Two behaviours were found when algal cells were exposed to intermediate concentrations of metals: Cu(II) and Cr(VI) induced a reduction of cell volume, while Cd(II) and Zn(II) provoked an opposite effect. The simultaneous nucleus staining and cell image analysis, allowed distinguishing three phases in P. subcapitata cell cycle: growth of mother cell; cell division, which includes two divisions of the nucleus; and, release of four autospores. The exposure of P. subcapitata cells to the highest metal concentrations resulted in the arrest of cell growth before the first nucleus division [for Cr(VI) and Cu(II)] or after the second nucleus division but before the cytokinesis (release of autospores) when exposed to Cd(II). The different impact of metals on algal cell volume and cell-cycle progression, suggests that different toxicity mechanisms underlie the action of different metals studied

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

    Energy Technology Data Exchange (ETDEWEB)

    Machado, Manuela D. [Bioengineering Laboratory-CIETI, Chemical Engineering Department, ISEP-School of Engineering of Polytechnic Institute of Porto, Rua Dr António Bernardino de Almeida, 431, 4200-072 Porto (Portugal); IBB-Institute for Biotechnology and Bioengineering, Centre for Biological Engineering, Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Soares, Eduardo V., E-mail: evs@isep.ipp.pt [Bioengineering Laboratory-CIETI, Chemical Engineering Department, ISEP-School of Engineering of Polytechnic Institute of Porto, Rua Dr António Bernardino de Almeida, 431, 4200-072 Porto (Portugal); IBB-Institute for Biotechnology and Bioengineering, Centre for Biological Engineering, Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal)

    2014-02-15

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

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

    Science.gov (United States)

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

    2015-01-01

    Sedentary plant-parasitic cyst nematodes are biotrophs that cause significant losses in agriculture. Parasitism is based on modifications of host root cells that lead to the formation of a hypermetabolic feeding site (a syncytium) from which nematodes withdraw nutrients. The host cell cycle is activated in an initial cell selected by the nematode for feeding, followed by activation of neighboring cells and subsequent expansion of feeding site through fusion of hundreds of cells. It is generally assumed that nematodes manipulate production and signaling of the plant hormone cytokinin to activate cell division. In fact, nematodes have been shown to produce cytokinin in vitro; however, whether the hormone is secreted into host plants and plays a role in parasitism remained unknown. Here, we analyzed the spatiotemporal activation of cytokinin signaling during interaction between the cyst nematode, Heterodera schachtii, and Arabidopsis using cytokinin-responsive promoter:reporter lines. Our results showed that cytokinin signaling is activated not only in the syncytium but also in neighboring cells to be incorporated into syncytium. An analysis of nematode infection on mutants that are deficient in cytokinin or cytokinin signaling revealed a significant decrease in susceptibility of these plants to nematodes. Further, we identified a cytokinin-synthesizing isopentenyltransferase gene in H. schachtii and show that silencing of this gene in nematodes leads to a significant decrease in virulence due to a reduced expansion of feeding sites. Our findings demonstrate the ability of a plant-parasitic nematode to synthesize a functional plant hormone to manipulate the host system and establish a long-term parasitic interaction. PMID:26417108

  16. 3′ UTR-Dependent, miR-92-Mediated Restriction of Tis21 Expression Maintains Asymmetric Neural Stem Cell Division to Ensure Proper Neocortex Size

    Directory of Open Access Journals (Sweden)

    Ji-Feng Fei

    2014-04-01

    Full Text Available Mammalian neocortex size primarily reflects the number and mode of divisions of neural stem and progenitor cells. Cortical stem cells (apical progenitors switching from symmetric divisions, which expand their population, to asymmetric divisions, which generate downstream neuronal progenitors (basal progenitors, start expressing Tis21, a so-called antiproliferative/prodifferentiative gene. Tis21 encodes a small (17.5 kDa, functionally poorly characterized protein and a relatively large (2 kb, highly conserved 3′ UTR. Here, we show that mice lacking the Tis21 3′ UTR develop a microcephalic neocortex with fewer neurons, notably in the upper layers. This reflects a progressive decrease in basal progenitors, which in turn is due to a fraction of apical progenitors prematurely switching from asymmetric self-renewing to symmetric self-consuming divisions. This switch is caused by the markedly increased Tis21 protein level resulting from lack of microRNA-, notably miR-92-, dependent restriction of Tis21 expression. Our data show that a premature onset of consumptive neural stem cell divisions can lead to microcephaly.

  17. Hsp70 protects mitotic cells against heat-induced centrosome damage and division abnormalities

    NARCIS (Netherlands)

    Hut, HMJ; Kampinga, HH; Sibon, OCM

    2005-01-01

    The effect of heat shock on centrosomes has been mainly studied in interphase cells. Centrosomes play a key role in proper segregation of DNA during mitosis. However, the direct effect and consequences of heat shock on mitotic cells and a possible cellular defense system against proteotoxic stress d

  18. Divisions of Identified Parvalbumin-Expressing Basket Cells during Working Memory-Guided Decision Making.

    Science.gov (United States)

    Lagler, Michael; Ozdemir, A Tugrul; Lagoun, Sabria; Malagon-Vina, Hugo; Borhegyi, Zsolt; Hauer, Romana; Jelem, Anna; Klausberger, Thomas

    2016-09-21

    Parvalbumin-expressing basket cells tightly control cortical networks and fire remarkably stereotyped during network oscillations and simple behaviors. How can these cells support multifaceted situations with different behavioral options and complex temporal sequences? We recorded from identified parvalbumin-expressing basket cells in prefrontal cortex of freely moving rats performing a multidimensional delayed cue-matching-to-place task, juxtacellularly filled recorded neurons for unequivocal histological identification, and determined their activity during temporally structured task episodes, associative working-memory, and stimulus-guided choice behavior. We show that parvalbumin-expressing basket cells do not fire homogenously, but individual cells were recruited or inhibited during different task episodes. Firing of individual basket cells was correlated with amount of presynaptic VIP (vasoactive intestinal polypeptide)-expressing GABAergic input. Together with subsets of pyramidal neurons, activity of basket cells differentiated for sequential actions and stimulus-guided choice behavior. Thus, interneurons of the same cell type can be recruited into different neuronal ensembles with distinct firing patterns to support multi-layered cognitive computations. PMID:27593181

  19. Contribution of soft substrates to malignancy and tumor suppression during colon cancer cell division.

    Directory of Open Access Journals (Sweden)

    Morgane Rabineau

    Full Text Available In colon cancer, a highly aggressive disease, progression through the malignant sequence is accompanied by increasingly numerous chromosomal rearrangements. To colonize target organs, invasive cells cross several tissues of various elastic moduli. Whether soft tissue increases malignancy or in contrast limits invasive colon cell spreading remains an open question. Using polyelectrolyte multilayer films mimicking microenvironments of various elastic moduli, we revealed that human SW480 colon cancer cells displayed increasing frequency in chromosomal segregation abnormalities when cultured on substrates with decreasing stiffness. Our results show that, although decreasing stiffness correlates with increased cell lethality, a significant proportion of SW480 cancer cells did escape from the very soft substrates, even when bearing abnormal chromosome segregation, achieve mitosis and undergo a new cycle of replication in contrast to human colonic HCoEpiC cells which died on soft substrates. This observation opens the possibility that the ability of cancer cells to overcome defects in chromosome segregation on very soft substrates could contribute to increasing chromosomal rearrangements and tumor cell aggressiveness.

  20. Actin microfilaments are associated with the migrating nucleus and the cell cortex in the green alga Micrasterias. Studies on living cells.

    Science.gov (United States)

    Meindl, U; Zhang, D; Hepler, P K

    1994-07-01

    Rhodamine-phalloidin or FITC-phalloidin has been injected in small amounts into living, developing cells of Micrasterias denticulata and the stained microfilaments visualized by confocal laser scanning microscopy. The results reveal that two different actin filament systems are present in a growing cell: a cortical actin network that covers the inner surface of the cell and is extended far into the tips of the lobes in both the growing and the nongrowing semicell; it is also associated with the surface of the chloroplast. The second actin system ensheathes the nucleus at the isthmus-facing side during nuclear migration. Its arrangement corresponds to that of the microtubule system that has been described in earlier electron microscopic investigations. The spatial correspondence between the distribution of actin filaments and microtubules suggests a cooperation between both cytoskeleton elements in generating the motive force for nuclear migration. The function of the cortical actin network is not yet clear. It may be involved in processes like transport and fusion of secretory vesicles and may also function in shaping and anchoring the chloroplast. PMID:7983159

  1. Functional expression of P2 purinoceptors in a primary neuroglial cell culture of the rat arcuate nucleus.

    Science.gov (United States)

    Pollatzek, Eric; Hitzel, Norma; Ott, Daniela; Raisl, Katrin; Reuter, Bärbel; Gerstberger, Rüdiger

    2016-07-01

    The arcuate nucleus (ARC) plays an important role in the hypothalamic control of energy homeostasis. Expression of various purinoceptor subtypes in the rat ARC and physiological studies suggest a modulatory function of P2 receptors within the neuroglial ARC circuitry. A differentiated mixed neuronal and glial microculture was therefore established from postnatal rat ARC, revealing neuronal expression of ARC-specific transmitters involved in food intake regulation (neuropeptide Y (NPY), proopiomelanocortin (POMC), tyrosine hydroxylase (TH)). Some NPYergic neurons cosynthesized TH, while POMC and TH expression proved to be mutually exclusive. Stimulation with the general purinoceptor agonists 2-methylthioadenosine-5'triphosphate (2-MeSATP) and ATP but not the P2X1/P2X3 receptor subtype agonist α,β-methyleneadenosine-5'triphosphate (α,β-meATP) induced intracellular calcium signals in ARC neurons and astrocytes. Some 5-10% each of 2-MeSATP responsive neurons expressed POMC, NYP or TH. Supporting the calcium imaging data, radioligand binding studies to hypothalamic membranes showed high affinity for 2-MeSATP, ATP but not α,β-meATP to displace [α-(35)S]deoxyadenosine-5'thiotriphosphate ([(35)S]dATPαS) from P2 receptors. Repetitive superfusion with equimolar 2-MeSATP allowed categorization of ARC cells into groups with a high or low (LDD) degree of purinoceptor desensitization, the latter allowing further receptor characterization. Calcium imaging experiments performed at 37°C vs. room temperature showed further reduction of desensitization. Agonist-mediated intracellular calcium signals were suppressed in all LDD neurons but only 25% of astrocytes in the absence of extracellular calcium, suggestive of metabotropic P2Y receptor expression in the majority of ARC astrocytes. The highly P2Y1-selective receptor agonists MRS2365 and 2-methylthioadenosine-5'diphosphate (2-MeSADP) activated 75-85% of all 2-MeSATP-responsive ARC astrocytes. Taking into consideration the

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

    CERN Document Server

    Wollman, Adam J M; Foster, Simon; Leake, Mark C

    2016-01-01

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

  3. Dynamics and Regulation of Actin Cytoskeleton in Plant Cells

    Institute of Scientific and Technical Information of China (English)

    Ren Haiyun

    2007-01-01

    @@ The actin cytoskeleton constituted of globular actin (G-actin) is a ubiquitous component of eukaryotic cells and plays crucial roles in diverse physiological processes in plant cells, such as cytoplasmic streaming, organelle and nucleus positioning, cell morphogenesis, cell division, tip growth, etc.

  4. Interaction with DNA and different effect on the nucleus of cancer cells for copper(II) complexes of N-benzyl di(pyridylmethyl)amine.

    Science.gov (United States)

    Chen, Qiu-Yun; Fu, Hai-Jian; Zhu, Wei-Hua; Qi, Yan; Ma, Zheng-Ping; Zhao, Kai-Di; Gao, Jing

    2011-05-01

    Three new copper(II) complexes of N-benzyl di(pyridylmethyl)amine (phdpa) were synthesized and characterized by spectroscopic methods. The interaction between CT-DNA and the complexes was studied by UV and fluorescence titration methods. It was found that the complex [(phdpa)Cu(H(2)O)Ac)](Ac), with the non-planar aromatic heterocyclic ring ligand (phdpa), showed good anticancer properties and could cause the fragmentation of the nucleus, although its interaction with CT-DNA was weaker than that of 1,10-phenanthroline (phen)-based copper(II) complexes. The anticancer activities of copper(II) complexes with phdpa and phen based ligands are correlated to their binding constants with DNA, but phen-based copper(II) complexes did not cause the nucleus fragmentation of HeLa cells. [(phdpa)Cu(H(2)O)Ac)](Ac) can noticeably decrease the oxygen content of a culture solution and of HeLa cells, which make it a new nucleus and oxygen related anticancer copper(II) complex. Information obtained here would be helpful in the design of new antitumor complexes in oxidative therapy.

  5. C. elegans nucleostemin is required for larval growth and germline stem cell division.

    Directory of Open Access Journals (Sweden)

    Michelle M Kudron

    Full Text Available The nucleolus has shown to be integral for many processes related to cell growth and proliferation. Stem cells in particular are likely to depend upon nucleolus-based processes to remain in a proliferative state. A highly conserved nucleolar factor named nucleostemin is proposed to be a critical link between nucleolar function and stem-cell-specific processes. Currently, it is unclear whether nucleostemin modulates proliferation by affecting ribosome biogenesis or by another nucleolus-based activity that is specific to stem cells and/or highly proliferating cells. Here, we investigate nucleostemin (nst-1 in the nematode C. elegans, which enables us to examine nst-1 function during both proliferation and differentiation in vivo. Like mammalian nucleostemin, the NST-1 protein is localized to the nucleolus and the nucleoplasm; however, its expression is found in both differentiated and proliferating cells. Global loss of C. elegans nucleostemin (nst-1 leads to a larval arrest phenotype due to a growth defect in the soma, while loss of nst-1 specifically in the germ line causes germline stem cells to undergo a cell cycle arrest. nst-1 mutants exhibit reduced levels of rRNAs, suggesting defects in ribosome biogenesis. However, NST-1 is generally not present in regions of the nucleolus where rRNA transcription and processing occurs, so this reduction is likely secondary to a different defect in ribosome biogenesis. Transgenic studies indicate that NST-1 requires its N-terminal domain for stable expression and both its G1 GTPase and intermediate domains for proper germ line function. Our data support a role for C. elegans nucleostemin in cell growth and proliferation by promoting ribosome biogenesis.

  6. A SAP domain-containing protein shuttles between the nucleus and cell membranes and plays a role in adhesion and migration in D. discoideum

    Directory of Open Access Journals (Sweden)

    Jessica S. Kelsey

    2013-02-01

    The AmpA protein reduces cell adhesion, thereby influencing cell migration in Dictyostelium. To understand how ampA influences cell migration, second site suppressors of an AmpA overexpressing cell line were created by REMI mutagenesis. Mutant candidates were identified by their ability to suppress the large plaques that the AmpA overexpressing cells form on bacterial lawns as a result of their increased rate of migration. One suppressor gene, sma, encodes an uncharacterized protein, which contains a SAP DNA-binding domain and a PTEN-like domain. Using sma gene knockouts and Sma-mRFP expressing cell lines, a role for sma in influencing cell migration was uncovered. Knockouts of the sma gene in a wild-type background enhanced chemotaxis. An additional role for Sma in influencing cell–cell adhesion was also demonstrated. Sma protein transitions between cytosolic and nuclear localizations as a function of cell density. In growing cells migrating to folic acid it is localized to regions of actin polymerization and absent from the nucleus. A role for Sma in influencing ampA mRNA levels is also demonstrated. Sma additionally appears to be involved in ampA pathways regulating cell size, actin polymerization, and cell substrate adhesion. We present insights to the SAP domain-containing group of proteins in Dictyostelium and provide evidence of a role for a SAP domain-containing protein shuttling from the nucleus to sites of actin polymerization during chemotaxis to folic acid and influencing the efficiency of migration.

  7. Sensory mother cell division is specifically affected in a Cyclin-A mutant of Drosophila melanogaster.

    OpenAIRE

    Ueda, R; Togashi, S; Takahisa, M; Tsurumura, S; Mikuni, M; Kondo, K.(Yamagata University, Yamagata, 992-8510, Japan); Miyake, T

    1992-01-01

    Cyclin proteins are one of the important components of the mechanism regulating mitosis in eukaryotic cells. We isolated a Drosophila Cyclin-A mutant in which the progenitor cells of the peripheral nervous system (the sensory mother cells) do not divide properly, causing the loss and other abnormalities of mechanosensory organs in the adult fly. Sequence analysis of the mutant genome reveals that a P element is inserted into the first intron of the Cyclin-A gene. A 13 kb wild-type genomic DNA...

  8. Oriented Cell Division in the C. elegans Embryo Is Coordinated by G-Protein Signaling Dependent on the Adhesion GPCR LAT-1

    OpenAIRE

    Antje Müller; Jana Winkler; Franziska Fiedler; Tania Sastradihardja; Claudia Binder; Ralf Schnabel; Jana Kungel; Sven Rothemund; Christian Hennig; Torsten Schöneberg; Simone Prömel

    2015-01-01

    Orientation of spindles and cell division planes during development of many species ensures that correct cell-cell contacts are established, which is vital for proper tissue formation. This is a tightly regulated process involving a complex interplay of various signals. The molecular mechanisms underlying several of these pathways are still incompletely understood. Here, we identify the signaling cascade of the C. elegans latrophilin homolog LAT-1, an essential player in the coordination of a...

  9. Function and regulation of Aurora/Ipl1p kinase family in cell division

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    During mitosis, the parent cell distributes its genetic materials equally into two daughter cells through chromosome segregation, a complex movements orchestrated by mitotic kinases and its effector proteins.Faithful chromosome segregation and cytokinesis ensure that each daughter cell receives a full copy of genetic materials of parent cell. Defects in these processes can lead to aneuploidy or polyploidy. Aurora/Ipl1p fanily,a class of conserved serine/threonine kinases, plays key roles in chromosome segregation and cytokinesis.This article highlights the function and regulation of Aurora/Ipl1p family in mitosis and provides potential links between aberrant regulation of Aurora/Ipl1p kinases and pathogenesis of human cancer.

  10. Redefining Langerhans Cell Histiocytosis as a Myeloid Dysplasia and Identifying B | Division of Cancer Prevention

    Science.gov (United States)

    DESCRIPTION (provided by applicant): Redefining Langerhans Cell Histiocytosis as a Myeloid Dysplasia and Identifying Biomarkers for Early Detection and Risk Assessment. This application addresses Program Announcement PA-09-197: Biomarkers for Early Detection of Hematopoietic Malignancies (R01). The overall aim of this project is to identify novel biomarkers that may be used to diagnose and treat patients with Langerhans Cell Histiocytosis (LCH). LCH occurs with similar frequency as other rare malignancies including Hodgkin's lymphoma and AML. |

  11. Dynamics of pre-replication complex proteins during the cell division cycle.

    OpenAIRE

    Prasanth, Supriya G.; Méndez, Juan; Prasanth, Kannanganattu V.; Stillman, Bruce

    2004-01-01

    Replication of the human genome every time a cell divides is a highly coordinated process that ensures accurate and efficient inheritance of the genetic information. The molecular mechanism that guarantees that many origins of replication fire only once per cell-cycle has been the area of intense research. The origin recognition complex (ORC) marks the position of replication origins in the genome and serves as the landing pad for the assembly of a multiprotein, pre-replicative complex (pre-R...

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

    Science.gov (United States)

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

    2015-06-05

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

  13. LGH00031, a novel ortho-quinonoid inhibitor of cell division cycle 25B, inhibits human cancer cells via ROS generation

    Institute of Scientific and Technical Information of China (English)

    Yu-bo ZHOU; Xu FENG; Li-na WANG; Jun-qing DU; Yue-yang ZHOU; Hai-ping YU; Yi ZANG; Jing-ya LI; Jia LI

    2009-01-01

    Aim: To discover novel cell division cycle 25 (CDC25) B inhibitors and elucidate the mechanisms of inhibition in cancer cells. Methods: Cell growth inhibition was detected by MTT assay, the cell cycle was analyzed by flow cytometry, and protein expression and phosphorylation was examined by Western blot analysis. Results: LGH00031 inhibited CDC25B irreversibly in vitro in a dose-dependent manner, and impaired the proliferation of tumor cell lines. In synchronized HeLa cells, LGH00031 delayed the cell cycle progression at the G2/M phase. LGH00031 increased cyclin-dependent kinase 1 (CDK1) tyrosine 15 phosphorylation and cyclin B1 protein level. The activity of LGH00031 against CDC25B in vitro relied on the existence of 1, 4-dithiothreitol (DTT) or dihydrolipoic acid and oxygen. The oxygen free radical scavenger catalase and superoxide dismutase reduced the inactivation of CDC25 by LGH00031, confirming that reactive oxygen species (ROS) mediate the inactivation process in vitro. LGH00031 accelerated cellular ROS production in a dose-dependent manner, and N-acetyl cysteine (NAC) markedly decreased the ROS production induced by LGH00031.Correspondingly, the LGH00031-induced decrease in cell viability and cell cycle arrest, cyclin B1 protein level, and phosphorylation of CDK1 tyrosine 15 were also rescued by NAC that decreased ROS pro-duction. Conclusion: The activity of LGH00031 at the molecular and cellular level is mediated by ROS.

  14. Three-Dimensional Organization of Chromosome Territories and the Human Cell Nucleus: Comparison between simulated Parameters and Experiments

    NARCIS (Netherlands)

    T.A. Knoch (Tobias)

    2000-01-01

    textabstractDespite the successful linear sequencing of the human genome its three-dimensional structure is widely unknown, although it is important for gene regulation and replication. For a long time the interphase nucleus has been viewed as a 'spaghetti soup' of DNA without much internal stru

  15. A decrease in the addition of new cells in the nucleus accumbens and prefrontal cortex between puberty and adulthood in male rats.

    Science.gov (United States)

    Staffend, Nancy A; Mohr, Margaret A; DonCarlos, Lydia L; Sisk, Cheryl L

    2014-06-01

    Adolescence involves shifts in social behaviors, behavioral flexibility, and adaptive risk-taking that coincide with structural remodeling of the brain. We previously showed that new cells are added to brain regions associated with sexual behaviors, suggesting that cytogenesis may be a mechanism for acquiring adult-typical behaviors during adolescence. Whether pubertal cell addition occurs in brain regions associated with behavioral flexibility or motivation and whether these patterns differ between pubertal and adult animals had not been determined. Therefore, we assessed patterns of cell proliferation or survival in the prefrontal cortex and nucleus accumbens. Pubertal and adult male rats were given injections of bromo-deoxyuridine (BrdU). To assess cell proliferation, half of the animals from each group were sacrificed 24 h following the last injection. The remaining animals were sacrificed at Day 30 following the last injection to evaluate cell survival. Adult animals had significantly lower densities of BrdU-immunoreactive (ir) cells in the prefrontal cortex, irrespective of post-BrdU survival time, whereas in the nucleus accumbens, adult animals had a lower density of BrdU-ir cells at the short survival time; however, the density of BrdU-ir cells was equivalent in pubertal and adult animals at the longer survival time. These data provide evidence that cell addition during puberty may contribute to the remodeling of brain regions associated with behavioral flexibility and motivation, and this cell addition continues into adulthood, albeit at lower levels. Higher levels of cell proliferation or survival in younger animals may reflect a higher level of plasticity, possibly contributing to the dynamic remodeling of the pubertal brain. PMID:24339170

  16. Eukaryotic checkpoints are absent in the cell division cycle of Entamoeba histolytica

    Indian Academy of Sciences (India)

    Sulagna Banerjee; Suchismita Das; Anuradha Lohia

    2002-11-01

    Fidelity in transmission of genetic characters is ensured by the faithful duplication of the genome, followed by equal segregation of the genetic material in the progeny. Thus, alternation of DNA duplication (S-phase) and chromosome segregation during the M-phase are hallmarks of most well studied eukaryotes. Several rounds of genome reduplication before chromosome segregation upsets this cycle and leads to polyploidy. Polyploidy is often witnessed in cells prior to differentiation, in embryonic cells or in diseases such as cancer. Studies on the protozoan parasite, Entamoeba histolytica suggest that in its proliferative phase, this organism may accumulate polyploid cells. It has also been shown that although this organism contains sequence homologs of genes which are known to control the cell cycle of most eukaryotes, these genes may be structurally altered and their equivalent function yet to be demonstrated in amoeba. The available information suggests that surveillance mechanisms or ‘checkpoints’ which are known to regulate the eukaryotic cell cycle may be absent or altered in E. histolytica.

  17. Nuclear localization of P-glycoprotein is responsible for protection of the nucleus from doxorubicin in the resistant LoVo cell line.

    Science.gov (United States)

    Szaflarski, Witold; Sujka-Kordowska, Patrycja; Januchowski, Radosław; Wojtowicz, Karolina; Andrzejewska, Małgorzata; Nowicki, Michał; Zabel, Maciej

    2013-07-01

    The high expression of P-glycoprotein (P-gp) belongs to one of the most important factors causing multidrug-resistant (MDR) of cancer cells. P-gp is primarily associated with plasma membrane; however, small fraction of that protein is present in the nuclear envelope. Such phenomenon is observed in cancer cells and may result in the selection of MDR cells as the secondary tumor and/or resistant metastasis that significantly shorten patient survival rate. Here, we confirmed nuclear localization of P-gp in resistant LoVo cells and demonstrated its impact on doxorubicin efflux from the nucleus to cytoplasm. Furthermore, we showed that P-gp located at the nuclear envelope might have a different glycoside chain when compared to the form located in the cytoplasm. It suggests that the glycoside chain plays a role in the intracellular trafficking of P-gp and may decide about the destination place in the cell. PMID:23602050

  18. Nuclear localization of P-glycoprotein is responsible for protection of the nucleus from doxorubicin in the resistant LoVo cell line.

    Science.gov (United States)

    Szaflarski, Witold; Sujka-Kordowska, Patrycja; Januchowski, Radosław; Wojtowicz, Karolina; Andrzejewska, Małgorzata; Nowicki, Michał; Zabel, Maciej

    2013-07-01

    The high expression of P-glycoprotein (P-gp) belongs to one of the most important factors causing multidrug-resistant (MDR) of cancer cells. P-gp is primarily associated with plasma membrane; however, small fraction of that protein is present in the nuclear envelope. Such phenomenon is observed in cancer cells and may result in the selection of MDR cells as the secondary tumor and/or resistant metastasis that significantly shorten patient survival rate. Here, we confirmed nuclear localization of P-gp in resistant LoVo cells and demonstrated its impact on doxorubicin efflux from the nucleus to cytoplasm. Furthermore, we showed that P-gp located at the nuclear envelope might have a different glycoside chain when compared to the form located in the cytoplasm. It suggests that the glycoside chain plays a role in the intracellular trafficking of P-gp and may decide about the destination place in the cell.

  19. Impact of Bep or Carboplatin Chemotherapy on Testicular Function and Sperm Nucleus of Subjects with Testicular Germ Cell Tumor.

    Science.gov (United States)

    Ghezzi, Marco; Berretta, Massimiliano; Bottacin, Alberto; Palego, Pierfrancesco; Sartini, Barbara; Cosci, Ilaria; Finos, Livio; Selice, Riccardo; Foresta, Carlo; Garolla, Andrea

    2016-01-01

    Young males have testicular germ cells tumors (TGCT) as the most common malignancy and its incidence is increasing in several countries. Besides unilateral orchiectomy (UO), the treatment of TGCT may include surveillance, radiotherapy, or chemotherapy (CT), basing on tumor histology and stage of disease. It is well known that both radio and CT may have negative effects on testicular function, affecting spermatogenesis, and sex hormones. Many reports investigated these aspects in patients treated with bleomycin, etoposide, and cisplatin (BEP), after UO. In contrast no data are available on the side effects of carboplatin treatment in these patients. We included in this study 212 consecutive subjects who undergone to sperm banking at our Andrology and Human Reproduction Unit after UO for TGCT. Hundred subjects were further treated with one or more BEP cycles (BEP-group), 54 with carboplatin (CARB group), and 58 were just surveilled (S-group). All patients were evaluated for seminal parameters, sperm aneuploidy, sperm DNA, sex hormones, volume of the residual testis at baseline (T0) and after 12 (T1) and 24 months (T2) from UO or end of CT. Seminal parameters, sperm aneuploidies, DNA status, gonadic hormones, and testicular volume at baseline were not different between groups. At T1, we observed a significant reduction of sperm concentration and sperm count in the BEP group versus baseline and versus both Carb and S-group. A significant increase of sperm aneuploidies was present at T1 in the BEP group. Similarly, the same group at 1 had altered sperm DNA integrity and fragmentation compared with baseline, S-group and Carb group. These alterations were persistent after 2 years from the end of BEP treatment. Despite a slight improvement at T2, the BEP group had still higher percentages of sperm aneuploidies than other groups. No impairment of sperm aneuploidies and DNA status were observed in the Carb group both after 1 and 2 years from the end of treatment. Despite

  20. IMPACT OF BEP OR CARBOPLATIN CHEMOTHERAPY ON TESTICULAR FUNCTION AND SPERM NUCLEUS OF SUBJECTS WITH TESTICULAR GERM CELL TUMOR

    Directory of Open Access Journals (Sweden)

    Marco eGhezzi

    2016-05-01

    Full Text Available Young males have testicular germ cells tumours (TGCT as the most common malignancy and its incidence is increasing in several countries. Besides unilateral orchiectomy (UO, the treatment of TGCT may include surveillance, radiotherapy or chemotherapy (CT, basing on tumour histology and stage of disease. It is well known that both radio and CT may have negative effects on testicular function, affecting spermatogenesis and sex hormones. Many reports investigated these aspects in patients treated with bleomycin, etoposide and cisplatin (BEP, after UO. In contrast no data are available on the side effects of carboplatin treatment in these patients. We included in this study 212 consecutive subjects who undergone to sperm banking at our Andrology and Human Reproduction Unit after UO for TGCT. Hundred subjects were further treated with one or more BEP cycles (BEP-group, 54 with carboplatin (Carb group and 58 were just surveilled (S-group. All patients were evaluated for seminal parameters, sperm aneuploidy, sperm DNA, sex hormones, volume of the residual testis at baseline (T0 and after 12 (T1 and 24 months (T2 from UO or end of CT. Seminal parameters, sperm aneuploidies, DNA status, gonadic hormones and testicular volume at baseline were not different between groups. At T1 we observed a significant reduction of sperm concentration and sperm count in the BEP group versus baseline and versus both Carb and S- group. A significant increase of sperm aneuploidies was present at T1 in the BEP group. Similarly, the same group at 1 had altered sperm DNA integrity and fragmentation compared with baseline, S group and Carb group. These alterations were persistent after two years from the end of BEP treatment. Despite a slight improvement at T2, the BEP group had still higher percentages of sperm aneuploidies than other groups. No impairment of sperm aneuploidies and DNA status were observed in the Carb group both after one and two years from the end of treatment

  1. Amaranth lunasin-like peptide internalizes into the cell nucleus and inhibits chemical carcinogen-induced transformation of NIH-3T3 cells.

    Science.gov (United States)

    Maldonado-Cervantes, Enrique; Jeong, Hyung Jin; León-Galván, Fabiola; Barrera-Pacheco, Alberto; De León-Rodríguez, Antonio; González de Mejia, Elvira; de Lumen, Ben O; Barba de la Rosa, Ana P

    2010-09-01

    Because an unbalanced diet is an important risk factor for several illnesses, interest has increased in finding novel health-promoting foods. Amaranth produces seeds that not only have substantial nutritional properties but that also contain phytochemical compounds as rutin and nicotiflorin and peptides with antihypertensive and anticarcinogenic activities. We report that a cancer-preventive peptide in amaranth has activities similar to those of soybean lunasin. The amaranth lunasin-like peptide, however, requires less time than the soybean lunasin to internalize into the nucleus of NIH-3T3 cells, and inhibits histone acetylation (H(3) and H(4) in a 70 and 77%, respectively). The amaranth lunasin-like peptide inhibited the transformation of NIH-3T3 cells to cancerous foci. The open reading frame (ORF) of amaranth lunasin corresponds to a bifunctional inhibitor/lipid-transfer protein (LTP). LTPs are a family of proteins that in plants are implicated in different functions, albeit all linked to developmental processes and biotic and abiotic stress resistance. Our results open new intriguing questions about the function of lunasin in plants and support that amaranth is a food alternative containing natural peptides with health-promoting benefits.

  2. In vivo robustness analysis of cell division cycle genes in Saccharomyces cerevisiae.

    Directory of Open Access Journals (Sweden)

    Hisao Moriya

    2006-07-01

    Full Text Available Intracellular biochemical parameters, such as the expression level of gene products, are considered to be optimized so that a biological system, including the parameters, works effectively. Those parameters should have some permissible range so that the systems have robustness against perturbations, such as noise in gene expression. However, little is known about the permissible range in real cells because there has been no experimental technique to test it. In this study, we developed a genetic screening method, named "genetic tug-of-war" (gTOW that evaluates upper limit copy numbers of genes in a model eukaryote Saccharomyces cerevisiae, and we applied it for 30 cell-cycle related genes (CDC genes. The experiment provided unique quantitative data that could be used to argue the system-level properties of the cell cycle such as robustness and fragility. The data were used to evaluate the current computational model, and refinements to the model were suggested.

  3. Treatment with IL-2 and IL-12 inhibits tumour cell division in SL2 lymphoma

    NARCIS (Netherlands)

    Masztalerz, A; Van Luyn, M; Werner, N; Molema, G; Everse, LA; Den Otter, W

    2004-01-01

    We examined which mechanism plays a dominant role in the rejection of solid SL2 lymphoma treated with locally applied IL-2 and /or IL-12. This treatment resulted in about 80% cures. There was a moderate influx of leukocytes in the tissue surrounding tumours; yet these cells failed to invade the soli

  4. The special case of hepatocytes : unique tissue architecture calls for a distinct mode of cell division

    NARCIS (Netherlands)

    Slim, Christiaan L; van IJzendoorn, Sven C D; Lázaro-Diéguez, Francisco; Müsch, Anne

    2014-01-01

    Columnar epithelia (e.g., kidney, intestine) and hepatocytes embody the two major organizational phenotypes of non-stratified epithelial cells. Columnar epithelia establish their apical and basal domains at opposing poles and organize in monolayered cysts and tubules, in which their apical surfaces

  5. Factors Influencing Academic Performance of Students Enrolled in a Lower Division Cell Biology Core Course

    Science.gov (United States)

    Soto, Julio G.; Anand, Sulekha

    2009-01-01

    Students' performance in two semesters of our Cell Biology course was examined for this study. Teaching strategies, behaviors, and pre-course variables were analyzed with respect to students' performance. Pre-semester and post-semester surveys were administered to ascertain students' perceptions about class difficulty, amount of study and effort…

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

    Science.gov (United States)

    Sesli, Ertugrul; Kara, Yilmaz

    2012-01-01

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

  7. Functional analysis of CedA based on its structure: residues important in binding of DNA and RNA polymerase and in the cell division regulation.

    Science.gov (United States)

    Abe, Yoshito; Fujisaki, Naoki; Miyoshi, Takanori; Watanabe, Noriko; Katayama, Tsutomu; Ueda, Tadashi

    2016-02-01

    DnaAcos, a mutant of the initiator DnaA, causes overinitiation of chromosome replication in Escherichia coli, resulting in inhibition of cell division. CedA was found to be a multi-copy suppressor which represses the dnaAcos inhibition of cell division. However, functional mechanism of CedA remains elusive except for previously indicated possibilities in binding to DNA and RNA polymerase. In this study, we searched for the specific sites of CedA in binding of DNA and RNA polymerase and in repression of cell division inhibition. First, DNA sequence to which CedA preferentially binds was determined. Next, the several residues and β4 region in CedA C-terminal domain was suggested to specifically interact with the DNA. Moreover, we found that the flexible N-terminal region was required for tight binding to longer DNA as well as interaction with RNA polymerase. Based on these results, several cedA mutants were examined in ability for repressing dnaAcos cell division inhibition. We found that the N-terminal region was dispensable and that Glu32 in the C-terminal domain was required for the repression. These results suggest that CedA has multiple roles and residues with different functions are positioned in the two regions.

  8. Molecular Evolution of Cell Division Proteins FtsA, FtsL, and FtsZ in Bacteria: A Phylogenetic Analysis

    Directory of Open Access Journals (Sweden)

    Rohini, K.

    2010-01-01

    Full Text Available In the past 16s rRNA gene sequencing has been used to find out the evolutionary pattern and the phylogenetic relationship among bacteria. Despite its accuracy, 16S rRNA gene sequence analysis lacks widespread use beyond the large reference laboratories because of technical and cost considerations. The rapid development of the field of proteomics has now been very helpful in finding the phylogenetic relationship of microorganisms. An attempt has been made in this study to find out the molecular evolution of three cell division proteins FtsZ, FtsA and FtsL among certain bacteria and possibility of studying their phylogenetic relationship using various proteomics databases and tools. For the present study various economically and medically important bacteria were selected. The amino acid residue sequence of the three cell division proteins FtsZ, FtsA and FtsL were retrieved from UniprotKB database. The sequences thus obtained for each cell division protein were subjected to Multiple Sequence analysis in ClustalW database. The molecular evolution and phylogenetic study has been performed using TreeDomViwer. The study clearly revealed that the cell division proteins do follow a definitive evolutionary pattern and is based on gram staining character rather than the morphology. The present study has also clearly shown that the important conserved protein sequences can be very useful to study the phylogeny of bacteria.

  9. Insights into nucleotide recognition by cell division protein FtsZ from a mant-GTP competition assay and molecular dynamics

    NARCIS (Netherlands)

    C. Schaffner-Barbero; R. Gil-Redondo; L.B. Ruiz-Avila; S. Huecas; T. Läppchen; T. den Blaauwen; J.F. Diaz; A. Morreale; J.M. Andreu

    2010-01-01

    Essential cell division protein FtsZ forms the bacterial cytokinetic ring and is a target for new antibiotics. FtsZ monomers bind GTP and assemble into filaments. Hydrolysis to GDP at the association interface between monomers leads to filament disassembly. We have developed a homogeneous competitio

  10. In silico prediction of escherichia coli proteins targeting the host cell nucleus, with special reference to their role in colon cancer etiology.

    Science.gov (United States)

    Khan, Abdul Arif

    2014-06-01

    The potential role of Escherichia coli in the development of colorectal carcinoma (CRC) has been investigated in many studies. Although the exact mechanism is not clear, chronic inflammation caused by E. coli and other related events are suggested as possible causes behind E. coli-induced colon cancer. It has been found that CRC cells, but not normal cells, are colonized by an intracellular form of E. coli. We predicted nuclear targeting of bacterial proteins in the host cell through computational tools nuclear localization signal (NLS) mapper and balanced subcellular localization predictor (BaCeILo). During intracellular E. coli residence, such targeting is highly likely and may have a possible role in colon cancer etiology. We observed that several gene expression-associated proteins of E. coli can migrate to the host nucleus during intracellular infections. This situation provides an opportunity for competitive interaction of host and pathogen proteins with similar cellular substrates, thereby increasing the chances of development of colon cancer. Moreover, the results indicated that proteins localized in the membrane of E. coli mostly act as secretary proteins in host cells. No exact correlation was observed between NLS prediction and nuclear localization prediction by BaCeILo. This is partly because of a number of reasons, including that only 30% of nuclear proteins carry NLS and that proteins <40 kDa molecular weight can passively target the host nucleus. This study concludes that detection of gene expression-specific E. coli proteins and their targeting of the nucleus may have a profound impact on CRC etiology. PMID:24611522

  11. IFT88 Plays a Cilia- and PCP-Independent Role in Controlling Oriented Cell Divisions during Vertebrate Embryonic Development

    Directory of Open Access Journals (Sweden)

    Antonia Borovina

    2013-10-01

    Full Text Available The role for cilia in establishing planar cell polarity (PCP is contentious. Although knockdown of genes known to function in ciliogenesis has been reported to cause PCP-related morphogenesis defects in zebrafish, genetic mutations affecting intraflagellar transport (IFT do not show PCP phenotypes despite the requirement for IFT in cilia formation. This discrepancy has been attributed to off-target effects of antisense morpholino oligonucleotide (MO injection, confounding maternal effects in zygotic mutant embryos, or an inability to distinguish between cilia-dependent versus cilia-independent protein functions. To determine the role of cilia in PCP, we generated maternal + zygotic IFT88 (MZift88 mutant zebrafish embryos, which never form cilia. We clearly demonstrate that cilia are not required to establish PCP. Rather, IFT88 plays a cilia-independent role in controlling oriented cell divisions at gastrulation and neurulation. Our results have important implications for the interpretation of cilia gene function in normal development and in disease.

  12. 微柱对细胞核形态影响的研究%Studys on Effects of Micropillars on Cell Nucleus Shapes

    Institute of Scientific and Technical Information of China (English)

    安燕飞; 王进义

    2015-01-01

    目的::探讨微柱对3种细胞细胞核形态的影响。方法:在高度10μm,直径18μm,间距15μm 的 PDMS 微柱上分别培养3种细胞(表皮细胞、内皮细胞和成纤维细胞),24 h 后对其细胞核形态参数包括平均面积、周长、纵横比以及圆度值进行测量,并与其在平面上的相应值进行比较分析。结果:微柱上表皮细胞和内皮细胞的细胞核变形明显,核平均面积较平面上小很多,出现了弯月形和哑铃形;而成纤维细胞核则变形较小,仍为椭圆形,只是纵横比增大。结论:本实验采用的微柱尺度会使得3种细胞有不同程度的细胞核变形。%Objective:Effects of micropillar on cell nucleus shapes of three different kinds of cells was discussed.Methods:First, these three different kinds of cells(epithelial cell,fibroblast and endothelial cell)were cultured on an array of PDMS micropillars which were 10 μm in height,18 μm in diameter and 15 μm in edge to edge spacing.Then,a quantitative and comparative analysis of the cell nucleus shapes was given by measuring the average area,aspect ratio and their circularity of the cells both on the micropillars and on the flat substrate.Results:Distinct nuclear deformation such as crescent,and dumbbell was observed of epithelial cells and endothelial cells on the micropillar substrate and their nuclear average areas were much smaller than that of the the cells on the flat substrate,when nucleus shape of fibroblasts was still in oval but just with a larger aspect ratio.Conclusion:Different degree of nuclear deformation would be induced by the micropillars that we used in this paper.

  13. Cytoskeleton, endoplasmic reticulum and nucleus alterations in CHO-K1 cell line after Crotalus durissus terrificus (South American rattlesnake venom treatment

    Directory of Open Access Journals (Sweden)

    B. P. Tamieti

    2007-01-01

    Full Text Available Snake venoms are toxic to a variety of cell types. However, the intracellular damages and the cell death fate induced by venom are unclear. In the present work, the action of the South American rattlesnake Crotalus durissus terrificus venom on CHO-K1 cell line was analyzed. The cells CHO-K1 were incubated with C. d. terrificus venom (10, 50 and 100g/ml for 1 and 24 hours, and structural alterations of actin filaments, endoplasmic reticulum and nucleus were assessed using specific fluorescent probes and agarose gel electrophoresis for DNA fragmentation. Significant structural changes were observed in all analyzed structures. DNA fragmentation was detected suggesting that, at the concentrations used, the venom induced apoptosis.

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

    Directory of Open Access Journals (Sweden)

    Hiroaki Kuroda

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

  15. Modeling of the dynamic pole-to-pole oscillations of the min proteins in bacterial cell division: The effect of an external field

    CERN Document Server

    Modchang, C; Triampo, W; Ngamsaad, W; Nuttawut, N; Tang, I M; Lenbury, Y; Modchang, Charin; Kanthang, Paisan; Triampo, Wannapong; Ngamsaad, Waipot; Nuttawut, Narin; Lenbury, Yongwimol

    2004-01-01

    One of the most important steps in the developmental process of the bacteria cell at the cellular level is the determination of the middle of the cell and the proper placement of the septum, these being essential to the division of the cell. In E. coli, this step depends on the proteins MinC, MinD, and MinE. Exposure to a constant electric field may cause the bacteria cell division mechanism to change, resulting in an abnormal cytokinesis. To see the effects of an external field e.g., an electric or magnetic field on this process, we have solved a set of deterministic reaction diffusion equations, which incorporate the influence of an electric field. We have found some changes in the dynamics of the oscillations of the min proteins from pole to pole. The numerical results show some interesting effects, which are qualitatively in good agreement with some experimental results.

  16. Insulin Phosphorylates Tyrosine Residue 464 of Tub and Translocates Tubby into the Nucleus in HIRcB Cells

    OpenAIRE

    Kim, Jin Wook; Kim, Hyeon Soo; Kim, Sang Dae; Park, Jung Yul

    2014-01-01

    Background The tubby protein has a motif that might be relevant for its action in the insulin signaling pathway. Previous studies have indicated that tubby undergoes phosphorylation on tyrosine residues in response to several stimuli and is known to localize in the nucleus as well as in the plasma membrane. However, the relationship between phosphorylation and nuclear translocation is not well understood. Here, we report that insulin directly phosphorylates tubby, which translocates into the ...

  17. Penetration of short fluorescence-labeled peptides into the nucleus in HeLa cells and in vitro specific interaction of the peptides with deoxyribooligonucleotides and DNA.

    Science.gov (United States)

    Fedoreyeva, L I; Kireev, I I; Khavinson, V Kh; Vanyushin, B F

    2011-11-01

    Marked fluorescence in cytoplasm, nucleus, and nucleolus was observed in HeLa cells after incubation with each of several fluorescein isothiocyanate-labeled peptides (epithalon, Ala-Glu-Asp-Gly; pinealon, Glu-Asp-Arg; testagen, Lys-Glu-Asp-Gly). This means that short biologically active peptides are able to penetrate into an animal cell and its nucleus and, in principle they may interact with various components of cytoplasm and nucleus including DNA and RNA. It was established that various initial (intact) peptides differently affect the fluorescence of the 5,6-carboxyfluorescein-labeled deoxyribooligonucleotides and DNA-ethidium bromide complexes. The Stern-Volmer constants characterizing the degree of fluorescence quenching of various single- and double-stranded fluorescence-labeled deoxyribooligonucleotides with short peptides used were different depending on the peptide primary structures. This indicates the specific interaction between short biologically active peptides and nucleic acid structures. On binding to them, the peptides discriminate between different nucleotide sequences and recognize even their cytosine methylation status. Judging from corresponding constants of the fluorescence quenching, the epithalon, pinealon, and bronchogen (Ala-Glu-Asp-Leu) bind preferentially with deoxyribooligonucleotides containing CNG sequence (CNG sites are targets for cytosine DNA methylation in eukaryotes). Epithalon, testagen, and pinealon seem to preferentially bind with CAG- but bronchogen with CTG-containing sequences. The site-specific interactions of peptides with DNA can control epigenetically the cell genetic functions, and they seem to play an important role in regulation of gene activity even at the earliest stages of life origin and in evolution.

  18. Macaque accessory optic system: I. Definition of the medial terminal nucleus

    International Nuclear Information System (INIS)

    The organization of the accessory optic system (AOS) has been studied in the macaque monkey following intravitreal injections of tritiated amino acids in one eye. Retinal projections to the dorsal (DTN) and the lateral (LTN) terminal nuclei are identical to those previously described in other primate species. We observed an additional group of retinorecipient cells of the AOS, located between the cerebral peduncle and the substantia nigra, which we define as the interstitial nucleus of the superior fasiculus, medial fibers. In this report, we focus our attention on the medial terminal nucleus (MTN). Although a ventral division of this nucleus (MTNv) was not observed in the macaque, the retina projects to a group of cells in the midbrain reticular formation (MRF), which we argue to be homologous to the dorsal division of the MTN (MTNd). To provide evidence in support of this homology, the retinal projection to the MTNv and MTNd was also examined in 21 additional species from 11 orders of mammals including carnivores, marsupials, lagomorphs, rodents, bats, insectivores, tree shrews, hyraxes, pholidotes, edentates, and five additional species of primates. Whereas the retina projects to both ventral and dorsal divisions in all species studied, in haplorhine primates only the projection to the MTNd is conserved. The relative topological position of the MTNd in the MRF, dorsomedial to the substantia nigra and ventrolateral to the red nucleus, remains constant throughout the mammals. The trajectory of fiber paths innervating the MTNd is also similar in all species. In addition, the MTNd has comparable afferent and efferent connections with retina, pretectum, and vestibular nuclei in all species thus far studied. These results support the unequivocal conclusion that the MTNd is an unvarying feature of the mammalian AOS

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

    Science.gov (United States)

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

    2014-08-22

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

  20. A trisubstituted benzimidazole cell division inhibitor with efficacy against Mycobacterium tuberculosis.

    Directory of Open Access Journals (Sweden)

    Susan E Knudson

    Full Text Available Trisubstituted benzimidazoles have demonstrated potency against Gram-positive and Gram-negative bacterial pathogens. Previously, a library of novel trisubstituted benzimidazoles was constructed for high throughput screening, and compounds were identified that exhibited potency against M. tuberculosis H37Rv and clinical isolates, and were not toxic to Vero cells. A new series of 2-cyclohexyl-5-acylamino-6-N, N-dimethylaminobenzimidazoles derivatives has been developed based on SAR studies. Screening identified compounds with potency against M. tuberculosis. A lead compound from this series, SB-P17G-A20, was discovered to have an MIC of 0.16 µg/mL and demonstrated efficacy in the TB murine acute model of infection based on the reduction of bacterial load in the lungs and spleen by 1.73 ± 0.24 Log10 CFU and 2.68 ± Log10 CFU, respectively, when delivered at 50 mg/kg by intraperitoneal injection (IP twice daily (bid. The activity of SB-P17G-A20 was determined to be concentration dependent and to have excellent stability in mouse and human plasma, and liver microsomes. Together, these studies demonstrate that SB-P17G-A20 has potency against M. tuberculosis clinical strains with varying susceptibility and efficacy in animal models of infection, and that trisubstituted benzimidazoles continue to be a platform for the development of novel inhibitors with efficacy.

  1. Learning Cell Biology as a Team: A Project-Based Approach to Upper-Division Cell Biology

    Science.gov (United States)

    Wright, Robin; Boggs, James

    2002-01-01

    To help students develop successful strategies for learning how to learn and communicate complex information in cell biology, we developed a quarter-long cell biology class based on team projects. Each team researches a particular human disease and presents information about the cellular structure or process affected by the disease, the cellular…

  2. CEH-20/Pbx and UNC-62/Meis function upstream of rnt-1/Runx to regulate asymmetric divisions of the C. elegans stem-like seam cells

    Directory of Open Access Journals (Sweden)

    Samantha Hughes

    2013-06-01

    Caenorhabditis elegans seam cells divide in the stem-like mode throughout larval development, with the ability to both self-renew and produce daughters that differentiate. Seam cells typically divide asymmetrically, giving rise to an anterior daughter that fuses with the hypodermis and a posterior daughter that proliferates further. Previously we have identified rnt-1 (a homologue of the mammalian cancer-associated stem cell regulator Runx as being an important regulator of seam development, acting to promote proliferation; rnt-1 mutants have fewer seam cells whereas overexpressing rnt-1 causes seam cell hyperplasia. We isolated the interacting CEH-20/Pbx and UNC-62/Meis TALE-class transcription factors during a genome-wide RNAi screen for novel regulators of seam cell number. Animals lacking wild type CEH-20 or UNC-62 display seam cell hyperplasia, largely restricted to the anterior of the worm, whereas double mutants have many additional seam cells along the length of the animal. The cellular basis of the hyperplasia involves the symmetrisation of normally asymmetric seam cell divisions towards the proliferative stem-like fate. The hyperplasia is completely suppressed in rnt-1 mutants, and rnt-1 is upregulated in ceh-20 and unc-62 mutants, suggesting that CEH-20 and UNC-62 function upstream of rnt-1 to limit proliferative potential to the appropriate daughter cell. In further support of this we find that CEH-20 is asymmetrically localised in seam daughters following an asymmetric division, being predominantly restricted to anterior nuclei whose fate is to differentiate. Thus, ceh-20 and unc-62 encode crucial regulators of seam cell division asymmetry, acting via rnt-1 to regulate the balance between proliferation and differentiation.

  3. An extract of Uncaria tomentosa inhibiting cell division and NF-kappa B activity without inducing cell death.

    Science.gov (United States)

    Akesson, Christina; Lindgren, Hanna; Pero, Ronald W; Leanderson, Tomas; Ivars, Fredrik

    2003-12-01

    Previous reports have demonstrated that extracts of the plant Uncaria tomentosa inhibit tumor cell proliferation and inflammatory responses. We have confirmed that C-Med 100, a hot water extract of this plant, inhibits tumor cell proliferation albeit with variable efficiency. We extend these findings by showing that this extract also inhibits proliferation of normal mouse T and B lymphocytes and that the inhibition is not caused by toxicity or by induction of apoptosis. Further, the extract did not interfere with IL-2 production nor IL-2 receptor signaling. Since there was no discrete cell cycle block in C-Med 100-treated cells, we propose that retarded cell cycle progression caused the inhibition of proliferation. Collectively, these data suggested interference with a common pathway controlling cell growth and cell cycle progression. Indeed, we provide direct evidence that C-Med 100 inhibits nuclear factor kappa B (NF-kappa B) activity and propose that this at least partially causes the inhibition of proliferation.

  4. DL-alpha-difluoromethylarginine inhibits intracellular Trypanosoma cruzi multiplication by affecting cell division but not trypomastigote-amastigote transformation.

    Science.gov (United States)

    Yakubu, M A; Basso, B; Kierszenbaum, F

    1992-06-01

    DL-alpha-difluoromethylarginine (DFMA), a specific, irreversible inhibitor of arginine decarboxylase (ADC), decreases the capacity of Trypanosoma cruzi to invade and multiply within different types of mammalian host cells in vitro. In this work we found that inhibition of intracellular growth results from selective impairment of amastigote division without appreciable alteration of the capacity of the invading trypomastigotes to transform into the replicative amastigote form. Addition of agmatine, the product of arginine decarboxylation, reversed the inhibitory effect of DFMA. Inhibition of ornithine decarboxylase activity by DL-alpha-difluoromethylornithine present in the medium prior to and during infection did not affect trypomastigote transformation or amastigote replication and did not change the magnitude of the inhibitory effect of DFMA on parasite multiplication. Hence, neither polyamine synthesis via the ornithine decarboxylase pathway nor salvage of host cell polyamines by T. cruzi appeared to be a likely explanation for the normal rate of parasite transformation that was seen in the presence of DFMA. Two clones of T. cruzi, TMSU-1 and TMSU-2, were tested for their degrees of sensitivity to the inhibitory effects of DFMA. Both trypomastigote association with (i.e., binding to and penetration of) myoblasts, and intracellular amastigote multiplication by either clone were found to be significantly (P less than 0.05) but not completely inhibited by DFMA. Therefore, the partial inhibition of T. cruzi infectivity and replication caused by DFMA is unlikely to represent a composite of effects of the drug on DFMA-sensitive and insensitive clones.(ABSTRACT TRUNCATED AT 250 WORDS)

  5. Treatment of peritoneal carcinomatosis by targeted delivery of the radio-labeled tumor homing peptide bi-DTPA-[F3]2 into the nucleus of tumor cells.

    Directory of Open Access Journals (Sweden)

    Enken Drecoll

    Full Text Available BACKGROUND: Alpha-particle emitting isotopes are effective novel tools in cancer therapy, but targeted delivery into tumors is a prerequisite of their application to avoid toxic side effects. Peritoneal carcinomatosis is a widespread dissemination of tumors throughout the peritoneal cavity. As peritoneal carcinomatosis is fatal in most cases, novel therapies are needed. F3 is a tumor homing peptide which is internalized into the nucleus of tumor cells upon binding to nucleolin on the cell surface. Therefore, F3 may be an appropriate carrier for alpha-particle emitting isotopes facilitating selective tumor therapies. PRINCIPAL FINDINGS: A dimer of the vascular tumor homing peptide F3 was chemically coupled to the alpha-emitter (213Bi ((213Bi-DTPA-[F3](2. We found (213Bi-DTPA-[F3](2 to accumulate in the nucleus of tumor cells in vitro and in intraperitoneally growing tumors in vivo. To study the anti-tumor activity of (213Bi-DTPA-[F3](2 we treated mice bearing intraperitoneally growing xenograft tumors with (213Bi-DTPA-[F3](2. In a tumor prevention study between the days 4-14 after inoculation of tumor cells 6x1.85 MBq (50 microCi of (213Bi-DTPA-[F3](2 were injected. In a tumor reduction study between the days 16-26 after inoculation of tumor cells 6x1.85 MBq of (213Bi-DTPA-[F3](2 were injected. The survival time of the animals was increased from 51 to 93.5 days in the prevention study and from 57 days to 78 days in the tumor reduction study. No toxicity of the treatment was observed. In bio-distribution studies we found (213Bi-DTPA-[F3](2 to accumulate in tumors but only low activities were found in control organs except for the kidneys, where (213Bi-DTPA-[F3](2 is found due to renal excretion. CONCLUSIONS/SIGNIFICANCE: In conclusion we report that (213Bi-DTPA-[F3](2 is a novel tool for the targeted delivery of alpha-emitters into the nucleus of tumor cells that effectively controls peritoneal carcinomatosis in preclinical models and may also be

  6. The Yb body, a major site for Piwi-associated RNA biogenesis and a gateway for Piwi expression and transport to the nucleus in somatic cells.

    Science.gov (United States)

    Qi, Hongying; Watanabe, Toshiaki; Ku, Hsueh-Yen; Liu, Na; Zhong, Mei; Lin, Haifan

    2011-02-01

    Despite exciting progress in understanding the Piwi-interacting RNA (piRNA) pathway in the germ line, less is known about this pathway in somatic cells. We showed previously that Piwi, a key component of the piRNA pathway in Drosophila, is regulated in somatic cells by Yb, a novel protein containing an RNA helicase-like motif and a Tudor-like domain. Yb is specifically expressed in gonadal somatic cells and regulates piwi in somatic niche cells to control germ line and somatic stem cell self-renewal. However, the molecular basis of the regulation remains elusive. Here, we report that Yb recruits Armitage (Armi), a putative RNA helicase involved in the piRNA pathway, to the Yb body, a cytoplasmic sphere to which Yb is exclusively localized. Moreover, co-immunoprecipitation experiments show that Yb forms a complex with Armi. In Yb mutants, Armi is dispersed throughout the cytoplasm, and Piwi fails to enter the nucleus and is rarely detectable in the cytoplasm. Furthermore, somatic piRNAs are drastically diminished, and soma-expressing transposons are desilenced. These observations indicate a crucial role of Yb and the Yb body in piRNA biogenesis, possibly by regulating the activity of Armi that controls the entry of Piwi into the nucleus for its function. Finally, we discovered putative endo-siRNAs in the flamenco locus and the Yb dependence of their expression. These observations further implicate a role for Yb in transposon silencing via both the piRNA and endo-siRNA pathways. PMID:21106531

  7. Differentiation of adipose-derived stem cells toward nucleus pulposuslike cells induced by hypoxia and a three-dimensional chitosan-alginate gel scaffold in vitro

    Institute of Scientific and Technical Information of China (English)

    Zhang Zhicheng; Li Fang; Tian Haiquan; Guan Kai; Zhao Guangmin; Shan Jianlin; Ren Dajiang

    2014-01-01

    Background Injectable three-dimensional (3D) scaffolds have the advantages of fluidity and moldability to fill irregularshaped defects,simple incorporation of bioactive factors,and limited surgical invasiveness.Adipose-derived stem cells (ADSCs) are multipotent and can be differentiated toward nucleus pulposus (NP)-Iike cells.A hypoxic environment may be important for differentiation to NP-like cells because the intervertebral disc is an avascular tissue.Hence,we investigated the induction effects of hypoxia and an injectable 3D chitosan-alginate (C/A) gel scaffold on ADSCs.Methods The C/A gel scaffold consisted of medical-grade chitosan and alginate.Gel porosity was calculated by liquid displacement method.Pore microstructure was analyzed by light and scanning electron microscopy.ADSCs were isolated and cultured by conventional methods.Passage 2 BrdU-labeled ADSCs we