WorldWideScience

Sample records for cell cytoskeleton organization

  1. Membrane tension and cytoskeleton organization in cell motility

    International Nuclear Information System (INIS)

    Cell membrane shape changes are important for many aspects of normal biological function, such as tissue development, wound healing and cell division and motility. Various disease states are associated with deregulation of how cells move and change shape, including notably tumor initiation and cancer cell metastasis. Cell motility is powered, in large part, by the controlled assembly and disassembly of the actin cytoskeleton. Much of this dynamic happens in close proximity to the plasma membrane due to the fact that actin assembly factors are membrane-bound, and thus actin filaments are generally oriented such that their growth occurs against or near the membrane. For a long time, the membrane was viewed as a relatively passive scaffold for signaling. However, results from the last five years show that this is not the whole picture, and that the dynamics of the actin cytoskeleton are intimately linked to the mechanics of the cell membrane. In this review, we summarize recent findings concerning the role of plasma membrane mechanics in cell cytoskeleton dynamics and architecture, showing that the cell membrane is not just an envelope or a barrier for actin assembly, but is a master regulator controlling cytoskeleton dynamics and cell polarity. (topical review)

  2. Probing cytoplasmic organization and the actin cytoskeleton of plant cells with optical tweezers

    NARCIS (Netherlands)

    Ketelaar, T.; Honing, van der H.S.; Emons, A.M.C.

    2010-01-01

    In interphase plant cells, the actin cytoskeleton is essential for intracellular transport and organization. To fully understand how the actin cytoskeleton functions as the structural basis for cytoplasmic organization, both molecular and physical aspects of the actin organization have to be conside

  3. Cytoskeleton and Cell Motility

    CERN Document Server

    Risler, Thomas

    2011-01-01

    The present article is an invited contribution to the Encyclopedia of Complexity and System Science, Robert A. Meyers Ed., Springer New York (2009). It is a review of the biophysical mechanisms that underly cell motility. It mainly focuses on the eukaryotic cytoskeleton and cell-motility mechanisms. Bacterial motility as well as the composition of the prokaryotic cytoskeleton is only briefly mentioned. The article is organized as follows. In Section III, I first present an overview of the diversity of cellular motility mechanisms, which might at first glance be categorized into two different types of behaviors, namely "swimming" and "crawling". Intracellular transport, mitosis - or cell division - as well as other extensions of cell motility that rely on the same essential machinery are briefly sketched. In Section IV, I introduce the molecular machinery that underlies cell motility - the cytoskeleton - as well as its interactions with the external environment of the cell and its main regulatory pathways. Sec...

  4. Spatial Organization of the Cytoskeleton enhances Cargo Delivery to Specific Target Areas on the Plasma Membrane of Spherical Cells

    CERN Document Server

    Hafner, Anne E

    2016-01-01

    Intracellular transport is vital for the proper functioning and survival of a cell. Cargo (proteins, vesicles, organelles, etc.) is transferred from its place of creation to its target locations via molecular motor assisted transport along cytoskeletal filaments. The transport efficiency is strongly affected by the spatial organization of the cytoskeleton, which constitutes an inhomogeneous, complex network. In cells with a centrosome microtubules grow radially from the central microtubule organizing center towards the cell periphery whereas actin filaments form a dense meshwork, the actin cortex, underneath the cell membrane with a broad range of orientations. The emerging ballistic motion along filaments is frequently interrupted due to constricting intersection nodes or cycles of detachment and reattachment processes in the crowded cytoplasm. In order to investigate the efficiency of search strategies established by the cell's specific spatial organization of the cytoskeleton we formulate a random velocity...

  5. VISUALIZATION OF DYNAMIC ORGANIZATION OF CYTOSKELETON GELS IN LIVING CELLS BY HYBRID-SPM

    Institute of Scientific and Technical Information of China (English)

    K.Kawabata; Y.Sado; M.Nagayama; T.Nitta; K.Nemoto; Y.Koyama; H.Haga

    2003-01-01

    We succeeded in performing of hybrid Scanning Probe Microscopy (hybrid-SPM) in which mechanical-SPM and fluorescence microscopy are combined. This technique is able to measure simultaneously mechanical properties and distribution of cytoskeletons of living cells by using green fluorescent protein. We measured evolution of both local elasticity and distributions of actin stress fibers in an identical fibroblast living in physiological conditions. The SPM experiments revealed that stiffer lines develop in living cells, which correspond to actin stress fibers. The elasticity of the actin stress fibers is as high as 100 kPa. We discuss mechanical effects on the development of actin filament networks.

  6. Estrogen-dependent sushi domain containing 3 regulates cytoskeleton organization and migration in breast cancer cells.

    Science.gov (United States)

    Moy, I; Todorović, V; Dubash, A D; Coon, J S; Parker, J B; Buranapramest, M; Huang, C C; Zhao, H; Green, K J; Bulun, S E

    2015-01-15

    Aromatase inhibitors (AIs) are the standard endocrine therapy for postmenopausal breast cancer; however, currently used biomarkers, such as, estrogen receptor-alpha/progesterone receptor (ERα/PR), predict only slightly more than half of the potential responders to AI treatment. To identify novel markers of AI responsiveness, a genome-wide microarray analysis was performed using primary breast tumor samples from 50 postmenopausal women who later developed metastatic breast cancer. Sushi domain containing 3 (SUSD3) is a significantly differentially expressed gene, with 3.38-fold higher mRNA levels in AI-responsive breast tumors vs non-responders (P<0.001). SUSD3 was highly expressed in ERα-positive breast tumors and treatment with estradiol increased SUSD3 expression in ERα-positive breast cancer cells. Treatment with an antiestrogen or ERα knockdown abolished basal and estradiol-dependent SUSD3 expression. Recruitment of ERα upstream of the transcription start site of SUSD3 was demonstrated by chromatin immunoprecipitation-PCR. Flow cytometric analysis of SUSD3-knockdown cells revealed blunted estradiol effects on progression into S and M phases. SUSD3 was localized to the plasma membrane of breast cancer cells. SUSD3 knockdown decreased the appearance of actin-rich protrusions, stress fibers and large basal focal adhesions, while increasing the presence of cortical actin concomitant with a decrease in Rho and focal adhesion kinase activity. SUSD3-deficient cells demonstrated diminished cell spreading, cell-cell adhesion and motility. In conclusion, SUSD3 is a novel promoter of estrogen-dependent cell proliferation and regulator of cell-cell and cell-substrate interactions and migration in breast cancer. It may serve as a novel predictor of response to endocrine therapy and potential therapeutic target. PMID:24413080

  7. Actin cytoskeleton organization, cell surface modification and invasion rate of 5 glioblastoma cell lines differing in PTEN and p53 status

    International Nuclear Information System (INIS)

    Glioblastoma cells exhibit highly invasive behavior whose mechanisms are not yet fully understood. The present study explores the relationship between the invasion capacity of 5 glioblastoma cell lines differing in p53 and PTEN status, expression of mTOR and several other marker proteins involved in cell invasion, actin cytoskeleton organization and cell morphology. We found that two glioblastoma lines mutated in both p53 and PTEN genes (U373-MG and SNB19) exhibited the highest invasion rates through the Matrigel or collagen matrix. In DK-MG (p53wt/PTENwt) and GaMG (p53mut/PTENwt) cells, F-actin mainly occurred in the numerous stress fibers spanning the cytoplasm, whereas U87-MG (p53wt/PTENmut), U373-MG and SNB19 (both p53mut/PTENmut) cells preferentially expressed F-actin in filopodia and lamellipodia. Scanning electron microscopy confirmed the abundant filopodia and lamellipodia in the PTEN mutated cell lines. Interestingly, the gene profiling analysis revealed two clusters of cell lines, corresponding to the most (U373-MG and SNB19, i.e. p53 and PTEN mutated cells) and less invasive phenotypes. The results of this study might shed new light on the mechanisms of glioblastoma invasion. - Highlights: • We examine 5 glioblastoma lines on the invasion capacity and actin cytoskeleton. • Glioblastoma cell lines mutated in both p53 and PTEN were the most invasive. • Less invasive cells showed much less lamellipodia, but more actin stress fibers. • A mechanism for the differences in tumor cell invasion is proposed

  8. Actin cytoskeleton organization, cell surface modification and invasion rate of 5 glioblastoma cell lines differing in PTEN and p53 status

    Energy Technology Data Exchange (ETDEWEB)

    Djuzenova, Cholpon S., E-mail: djuzenova_t@ukw.de [Department of Radiation Oncology, University Hospital, Josef-Schneider-Strasse 11, D-97080 Würzburg (Germany); Fiedler, Vanessa [Department of Radiation Oncology, University Hospital, Josef-Schneider-Strasse 11, D-97080 Würzburg (Germany); Memmel, Simon [Lehrstuhl für Biotechnologie und Biophysik, Universität Würzburg, Biozentrum Am Hubland, 97070 Würzburg (Germany); Katzer, Astrid; Hartmann, Susanne [Department of Radiation Oncology, University Hospital, Josef-Schneider-Strasse 11, D-97080 Würzburg (Germany); Krohne, Georg [Elektronenmikroskopie, Biozentrum, Universität Würzburg, Am Hubland, 97070 Würzburg (Germany); Zimmermann, Heiko [Hauptabteilung Biophysik and Kryotechnologie, Fraunhofer-Institut für Biomedizinische Technik, Lehrstuhl für Molekulare und Zelluläre Biotechnologie/Nanotechnologie, Universität des Saarlandes, Ensheimer Strasse 48, 66386 St. Ingbert (Germany); Scholz, Claus-Jürgen [Interdisciplinary Center for Clinical Research, University Hospital, Versbacher Strasse 7, 97078 Würzburg (Germany); Polat, Bülent; Flentje, Michael [Department of Radiation Oncology, University Hospital, Josef-Schneider-Strasse 11, D-97080 Würzburg (Germany); and others

    2015-01-15

    Glioblastoma cells exhibit highly invasive behavior whose mechanisms are not yet fully understood. The present study explores the relationship between the invasion capacity of 5 glioblastoma cell lines differing in p53 and PTEN status, expression of mTOR and several other marker proteins involved in cell invasion, actin cytoskeleton organization and cell morphology. We found that two glioblastoma lines mutated in both p53 and PTEN genes (U373-MG and SNB19) exhibited the highest invasion rates through the Matrigel or collagen matrix. In DK-MG (p53wt/PTENwt) and GaMG (p53mut/PTENwt) cells, F-actin mainly occurred in the numerous stress fibers spanning the cytoplasm, whereas U87-MG (p53wt/PTENmut), U373-MG and SNB19 (both p53mut/PTENmut) cells preferentially expressed F-actin in filopodia and lamellipodia. Scanning electron microscopy confirmed the abundant filopodia and lamellipodia in the PTEN mutated cell lines. Interestingly, the gene profiling analysis revealed two clusters of cell lines, corresponding to the most (U373-MG and SNB19, i.e. p53 and PTEN mutated cells) and less invasive phenotypes. The results of this study might shed new light on the mechanisms of glioblastoma invasion. - Highlights: • We examine 5 glioblastoma lines on the invasion capacity and actin cytoskeleton. • Glioblastoma cell lines mutated in both p53 and PTEN were the most invasive. • Less invasive cells showed much less lamellipodia, but more actin stress fibers. • A mechanism for the differences in tumor cell invasion is proposed.

  9. Spatial constraints and the organization of the cytoskeleton

    NARCIS (Netherlands)

    Ga^rlea, I.C.

    2015-01-01

    The shape of animal cells is in controlled by a network of filamentous polymers called the cytoskeleton. The two main components of the cytoskeleton are actin filaments and microtubules. These polymers continuously reorganize in order to performed their diverse cellular functions. For example, in pr

  10. Spatial constraints and the organization of the cytoskeleton

    OpenAIRE

    Ga^rlea, I.C.

    2015-01-01

    The shape of animal cells is in controlled by a network of filamentous polymers called the cytoskeleton. The two main components of the cytoskeleton are actin filaments and microtubules. These polymers continuously reorganize in order to performed their diverse cellular functions. For example, in processes such as cell migration actin filaments grow against the membrane, creating flat protrusions called lamellipodia. The lamellipodia enable the cells to move over surfaces. Microtubules are a ...

  11. Cell Elasticity Is Regulated by the Tropomyosin Isoform Composition of the Actin Cytoskeleton

    OpenAIRE

    Jalilian, Iman; Heu, Celine; Cheng, Hong; Freittag, Hannah; Desouza, Melissa; Justine R. Stehn; Bryce, Nicole S.; Whan, Renee M.; Hardeman, Edna C.; Fath, Thomas; Schevzov, Galina; Gunning, Peter W.

    2015-01-01

    The actin cytoskeleton is the primary polymer system within cells responsible for regulating cellular stiffness. While various actin binding proteins regulate the organization and dynamics of the actin cytoskeleton, the proteins responsible for regulating the mechanical properties of cells are still not fully understood. In the present study, we have addressed the significance of the actin associated protein, tropomyosin (Tpm), in influencing the mechanical properties of cells. Tpms belong to...

  12. New insights into the structural organization of eukaryotic and prokaryotic cytoskeletons using cryo-electron tomography

    International Nuclear Information System (INIS)

    Cryo-electron tomography (cryo-ET) is an emerging imaging technology that combines the potential of three-dimensional (3-D) imaging at molecular resolution (<5 nm) with a close-to-life preservation of the specimen. In conjunction with pattern recognition techniques, it enables us to map the molecular landscape inside cells. The application of cryo-ET to intact cells provides novel insights into the structure and the spatial organization of the cytoskeleton in prokaryotic and eukaryotic cells

  13. 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.

  14. Alterations of the cytoskeleton in human cells in space proved by life-cell imaging

    OpenAIRE

    Corydon, Thoma J.; Kopp, Sascha; Wehland, Markus; Braun, Markus; Schütte, Andrea; Meyer, Tobias; Hülsing, Thomas; Oltmann, Hergen; Schmitz, Burkhard; Hemmersbach, Ruth; Grimm, Daniela

    2016-01-01

    Microgravity induces changes in the cytoskeleton. This might have an impact on cells and organs of humans in space. Unfortunately, studies of cytoskeletal changes in microgravity reported so far are obligatorily based on the analysis of fixed cells exposed to microgravity during a parabolic flight campaign (PFC). This study focuses on the development of a compact fluorescence microscope (FLUMIAS) for fast live-cell imaging under real microgravity. It demonstrates the application of the instru...

  15. Alterations of the cytoskeleton in human cells in space proved by life-cell imaging

    DEFF Research Database (Denmark)

    Corydon, Thomas J; Kopp, Sascha; Wehland, Markus; Braun, Markus; Schütte, Andreas; Mayer, Tobias; Hülsing, Thomas; Oltmann, Hergen; Schmitz, Burkhard; Hemmersbach, Ruth; Grimm, Daniela

    2016-01-01

    campaign (PFC). This study focuses on the development of a compact fluorescence microscope (FLUMIAS) for fast live-cell imaging under real microgravity. It demonstrates the application of the instrument for on-board analysis of cytoskeletal changes in FTC-133 cancer cells expressing the Lifeact-GFP marker......Microgravity induces changes in the cytoskeleton. This might have an impact on cells and organs of humans in space. Unfortunately, studies of cytoskeletal changes in microgravity reported so far are obligatorily based on the analysis of fixed cells exposed to microgravity during a parabolic flight...... protein for the visualization of F-actin during the 24(th) DLR PFC and TEXUS 52 rocket mission. Although vibration is an inevitable part of parabolic flight maneuvers, we successfully for the first time report life-cell cytoskeleton imaging during microgravity, and gene expression analysis after the 31(st...

  16. FAM83H and casein kinase I regulate the organization of the keratin cytoskeleton and formation of desmosomes.

    Science.gov (United States)

    Kuga, Takahisa; Sasaki, Mitsuho; Mikami, Toshinari; Miake, Yasuo; Adachi, Jun; Shimizu, Maiko; Saito, Youhei; Koura, Minako; Takeda, Yasunori; Matsuda, Junichiro; Tomonaga, Takeshi; Nakayama, Yuji

    2016-01-01

    FAM83H is essential for the formation of dental enamel because a mutation in the FAM83H gene causes amelogenesis imperfecta (AI). We previously reported that the overexpression of FAM83H often occurs and disorganizes the keratin cytoskeleton in colorectal cancer cells. We herein show that FAM83H regulates the organization of the keratin cytoskeleton and maintains the formation of desmosomes in ameloblastoma cells. FAM83H is expressed and localized on keratin filaments in human ameloblastoma cell lines and in mouse ameloblasts and epidermal germinative cells in vivo. FAM83H shows preferential localization to keratin filaments around the nucleus that often extend to cell-cell junctions. Alterations in the function of FAM83H by its overexpression, knockdown, or an AI-causing truncated mutant prevent the proper organization of the keratin cytoskeleton in ameloblastoma cells. Furthermore, the AI-causing mutant prevents desmosomal proteins from being localized to cell-cell junctions. The effects of the AI-causing mutant depend on its binding to and possible inhibition of casein kinase I (CK-1). The suppression of CK-1 by its inhibitor, D4476, disorganizes the keratin cytoskeleton. Our results suggest that AI caused by the FAM83H mutation is mediated by the disorganization of the keratin cytoskeleton and subsequent disruption of desmosomes in ameloblasts. PMID:27222304

  17. FAM83H and casein kinase I regulate the organization of the keratin cytoskeleton and formation of desmosomes

    Science.gov (United States)

    Kuga, Takahisa; Sasaki, Mitsuho; Mikami, Toshinari; Miake, Yasuo; Adachi, Jun; Shimizu, Maiko; Saito, Youhei; Koura, Minako; Takeda, Yasunori; Matsuda, Junichiro; Tomonaga, Takeshi; Nakayama, Yuji

    2016-01-01

    FAM83H is essential for the formation of dental enamel because a mutation in the FAM83H gene causes amelogenesis imperfecta (AI). We previously reported that the overexpression of FAM83H often occurs and disorganizes the keratin cytoskeleton in colorectal cancer cells. We herein show that FAM83H regulates the organization of the keratin cytoskeleton and maintains the formation of desmosomes in ameloblastoma cells. FAM83H is expressed and localized on keratin filaments in human ameloblastoma cell lines and in mouse ameloblasts and epidermal germinative cells in vivo. FAM83H shows preferential localization to keratin filaments around the nucleus that often extend to cell-cell junctions. Alterations in the function of FAM83H by its overexpression, knockdown, or an AI-causing truncated mutant prevent the proper organization of the keratin cytoskeleton in ameloblastoma cells. Furthermore, the AI-causing mutant prevents desmosomal proteins from being localized to cell-cell junctions. The effects of the AI-causing mutant depend on its binding to and possible inhibition of casein kinase I (CK-1). The suppression of CK-1 by its inhibitor, D4476, disorganizes the keratin cytoskeleton. Our results suggest that AI caused by the FAM83H mutation is mediated by the disorganization of the keratin cytoskeleton and subsequent disruption of desmosomes in ameloblasts. PMID:27222304

  18. Alterations of the cytoskeleton in human cells in space proved by life-cell imaging.

    Science.gov (United States)

    Corydon, Thomas J; Kopp, Sascha; Wehland, Markus; Braun, Markus; Schütte, Andreas; Mayer, Tobias; Hülsing, Thomas; Oltmann, Hergen; Schmitz, Burkhard; Hemmersbach, Ruth; Grimm, Daniela

    2016-01-01

    Microgravity induces changes in the cytoskeleton. This might have an impact on cells and organs of humans in space. Unfortunately, studies of cytoskeletal changes in microgravity reported so far are obligatorily based on the analysis of fixed cells exposed to microgravity during a parabolic flight campaign (PFC). This study focuses on the development of a compact fluorescence microscope (FLUMIAS) for fast live-cell imaging under real microgravity. It demonstrates the application of the instrument for on-board analysis of cytoskeletal changes in FTC-133 cancer cells expressing the Lifeact-GFP marker protein for the visualization of F-actin during the 24(th) DLR PFC and TEXUS 52 rocket mission. Although vibration is an inevitable part of parabolic flight maneuvers, we successfully for the first time report life-cell cytoskeleton imaging during microgravity, and gene expression analysis after the 31(st) parabola showing a clear up-regulation of cytoskeletal genes. Notably, during the rocket flight the FLUMIAS microscope reveals significant alterations of the cytoskeleton related to microgravity. Our findings clearly demonstrate the applicability of the FLUMIAS microscope for life-cell imaging during microgravity, rendering it an important technological advance in live-cell imaging when dissecting protein localization. PMID:26818711

  19. Dynamic organization of actin cytoskeleton during the polarity formation and germination of pollen protoplasts

    Institute of Scientific and Technical Information of China (English)

    XU Xia; Zl Huijun; SUN Yina; REN Haiyun

    2004-01-01

    The formation of the polarity of pollen protoplast and the dynamics of actin cytoskeleton were observed by non-fixation, Alexa-Phalloidin probing and confocal laser scanning microscopy. Our results showed that the protoplast obtained from stored pollen contained numerous crystalline fusiform bodies to constitute a storage form of actin. When dormant pollen was hydrated, the actin cytoskeleton forms a fine network spreading uniformly in the protoplast. In the process of polarity formation and germination of pollen protoplast, actin filaments marshaled slowly to the brim, and then formed multilayer continuous actin filament bundles surrounding the cortical of the protoplast. When the protoplast was exposed to actin filament-disrupting drugs, such as Latrunculin A and Cytochalasin D, continuously arranged actin bundles were disturbed and in this condition, the protoplast could not germinate. But when exposed to actin filament stabiling drug-phalliodin, the dynamics of actin filaments in the protoplasts behaved normally and the protoplasts could germinate normally. These results were also confirmed by the pharmacology experiments on pollen grains. And when Latrunculin A or Cytochalasin D was washed off, the ratio of pollen germination was resumed partly. All the results above show that the dynamic organization of the actin cytoskeleton are critical in the cell polarity formation and germination of pollen protoplast, and that the reorganization of actin cytoskeleton is mainly due to the rearrangement of actin filament arrays.

  20. Course 6: Physics of Composite Cell Membrane and Actin Based Cytoskeleton

    Science.gov (United States)

    Sackmann, E.; Bausch, A. R.; Vonna, L.

    1 Architecture of composite cell membranes 1.1 The lipid/protein bilayer is a multicomponent smectic phase with mosaic like architecture 1.2 The spectrin/actin cytoskeleton as hyperelastic cell stabilizer 1.3 The actin cortex: Architecture and function 2 Physics of the actin based cytoskeleton 2.1 Actin is a living semiflexible polymer 2.2 Actin network as viscoelastic body 2.3 Correlation between macroscopic viscoelasticity and molecular 3 Heterogeneous actin gels in cells and biological function 3.1 Manipulation of actin gels 3.2 Control of organization and function of actin cortex by cell signalling 4 Micromechanics and microrheometry of cells 5 Activation of endothelial cells: On the possibility of formation of stress fibers as phase transition of actin-network triggered by cell signalling pathways 6 On cells as adaptive viscoplastic bodies 7 Controll of cellular protrusions controlled by actin/myosin cortex

  1. Mechanism of aftered cytoskeleton organization in influenza virus infection

    International Nuclear Information System (INIS)

    The autophosphorylation was followed of cytoskeleton (CS) isolated from control chick embryo cell membranes (CS-C) and from these membranes after influenza virus adsorption (CS-V) under conditions allowing to determine the activity of a single type proteinkinase. The Ca2+ dependent calmodulin (CaM) kinase used different substrates from CS-V than did the c'AMP dependent proteinkinase. The catalytic subunit (c-subunit) of the c'AMP dependent proteinkinase added from outside phosphorylated the same polypeptides than the endogeneous c'AMP dependent proteinkinase, the further being more active than the latter. The purified influenza virus incorporated 32P in the presence of the c-subunit only. Incubation of influenza virus with the c-subunit caused morphological changes visible by electron microscopy. The pleomorphy of the particles as well as their electron transmissibility were enhanced in the result of structural alterations and rarefaction of surface spikes of the haemagglutinin and neuraminidase. The contractibility of CS isolated from normal CEC and of the CS from CEC by 15 min postinfection (p.i.) was determined according to the actomyosin ATPase activity. The ATPase activity of the cytoskeleton in the presence of the Ca2+/CaM and that in the presence of c'AMP were used as controls. The virus as well as the Ca2+/CaM increased the ATPase activity. EGTA had no effect but did not interfere with virus stimulation, while c'AMP blocked the virus-induced enhancement of the ATPase activity. (author). 3 figs., 1 tab., 36 refs

  2. Direct Cytoskeleton Forces Cause Membrane Softening in Red Blood Cells

    Science.gov (United States)

    Rodríguez-García, Ruddi; López-Montero, Iván; Mell, Michael; Egea, Gustavo; Gov, Nir S.; Monroy, Francisco

    2015-01-01

    Erythrocytes are flexible cells specialized in the systemic transport of oxygen in vertebrates. This physiological function is connected to their outstanding ability to deform in passing through narrow capillaries. In recent years, there has been an influx of experimental evidence of enhanced cell-shape fluctuations related to metabolically driven activity of the erythroid membrane skeleton. However, no direct observation of the active cytoskeleton forces has yet been reported to our knowledge. Here, we show experimental evidence of the presence of temporally correlated forces superposed over the thermal fluctuations of the erythrocyte membrane. These forces are ATP-dependent and drive enhanced flickering motions in human erythrocytes. Theoretical analyses provide support for a direct force exerted on the membrane by the cytoskeleton nodes as pulses of well-defined average duration. In addition, such metabolically regulated active forces cause global membrane softening, a mechanical attribute related to the functional erythroid deformability. PMID:26083919

  3. p38 MAPK-dependent shaping of the keratin cytoskeleton in cultured cells

    OpenAIRE

    Wöll, Stefan; Windoffer, Reinhard; Leube, Rudolf E.

    2007-01-01

    Plasticity of the resilient keratin intermediate filament cytoskeleton is an important prerequisite for epithelial tissue homeostasis. Here, the contribution of stress-activated p38 MAPK to keratin network organization was examined in cultured cells. It was observed that phosphorylated p38 colocalized with keratin granules that were rapidly formed in response to orthovanadate. The same p38p recruitment was noted during mitosis, in various stress situations and in cells producing mutant kerati...

  4. Ion Implantation Hampers Pollen Tube Growth and Disrupts Actin Cytoskeleton Organization in Pollen Tubes of Pinus thunbergii

    Institute of Scientific and Technical Information of China (English)

    LI Guoping; HUANG Qunce; YANG Lusheng; QIN Guangyong

    2008-01-01

    Pollen grains of Pinus thunbergii Parl. (Japanese black pine) were implanted with 30 keV nitrogen ion beams and the effects of nitrogen ion implantation on pollen tube growth in vitro and the organization of actin cytoskeleton in the pollen tube cell were investigated using a confocal laser scanning microscope after fluorescence labeling. Treatment with ion implanta-tion significantly blocked pollen tube growth. Confocal microscopy showed that ion implantation disrupted actin filament cytoskeleton organization in the pollen tube. It was found that there was a distinct correlation between the inhibition of pollen tube growth and the disruption of actin cytoskeleton organization, indicating that an intact actin cytoskeleton is essential for con-tinuous pollen tube elongation in Pinus thunbergii. Although the detailed mechanism for the ion-implantation-induced bioeffect still remains to be elucidated, the present study assumes that the cytoskeleton system in pollen grains may provide a key target in response to ion beam im-plantation and is involved in mediating certain subsequent cytological changes.

  5.  Oxidative stress modulates the organization of erythrocyte membrane cytoskeleton

    Directory of Open Access Journals (Sweden)

    Maria Olszewska

    2012-07-01

    Full Text Available  Background:Apart from their main role in transporting oxygen and carbon dioxide, erythrocytes play also an important role in organism antioxidative defence. Direct exposure to reactive oxygen species (ROS results in shortening of their half-life, even by 50�20The presence of glucose, being the substrate in pentose phosphate pathway (PPP cycle, is one of the factors that can have influence on the level of oxidative stress. The activity of PPP increases during oxidative stress. Glucose guarantees normal PPP functioning with the production of reductive equivalents in the amounts necessary to reproduction of glutathione – nonenzymatic free radical scavenger. In available literature there are no reports regarding the changes in protein contents of erythrocyte cytoskeleton exposed to t-butyl hydroperoxide in relation to glucose presence in incubation medium.Material/methods:Erythrocytes taken from 10 healthy subjects were used to assess the influence of generated free radicals on erythrocyte proteins and chosen parameters of oxidative stress. Erythrocytes were incubated in the solutions containing deferent concentrations of t-butyl hydroperoxide and glucose. Electrophoresis was performed on polyacrylamide gel in denaturating conditions. The contents of tryptophan in membranes was evaluated spectrofluorometrically.Results/conclusions:In vitro conditions oxidative stress leads to protein damage in erythrocyte cytoskeleton, both in proteins inside the cell as well as having contact with extracellular environment. In consequence, the amount of low-molecular proteins – mainly globin, which bind to cytoskeleton, increases. This process takes place independently of glucose presence in incubation medium. One of the element of protein cytoskeleton, tryptophan, also undergoes degradation. The decrease of its contents is higher during erythrocyte exposure to t-BOOH in environment containing glucose, what can suggest prooxidative influence of glucose in

  6. Calponin 3 regulates actin cytoskeleton rearrangement in trophoblastic cell fusion.

    Science.gov (United States)

    Shibukawa, Yukinao; Yamazaki, Natsuko; Kumasawa, Keiichi; Daimon, Etsuko; Tajiri, Michiko; Okada, Yuka; Ikawa, Masahito; Wada, Yoshinao

    2010-11-15

    Cell-cell fusion is an intriguing differentiation process, essential for placental development and maturation. A proteomic approach identified a cytoplasmic protein, calponin 3 (CNN3), related to the fusion of BeWo choriocarcinoma cells. CNN3 was expressed in cytotrophoblasts in human placenta. CNN3 gene knockdown promoted actin cytoskeletal rearrangement and syncytium formation in BeWo cells, suggesting CNN3 to be a negative regulator of trophoblast fusion. Indeed, CNN3 depletion promoted BeWo cell fusion. CNN3 at the cytoplasmic face of cytoskeleton was dislocated from F-actin with forskolin treatment and diffused into the cytoplasm in a phosphorylation-dependent manner. Phosphorylation sites were located at Ser293/296 in the C-terminal region, and deletion of this region or site-specific disruption of Ser293/296 suppressed syncytium formation. These CNN3 mutants were colocalized with F-actin and remained there after forskolin treatment, suggesting that dissociation of CNN3 from F-actin is modulated by the phosphorylation status of the C-terminal region unique to CNN3 in the CNN family proteins. The mutant missing these phosphorylation sites displayed a dominant negative effect on cell fusion, while replacement of Ser293/296 with aspartic acid enhanced syncytium formation. These results indicated that CNN3 regulates actin cytoskeleton rearrangement which is required for the plasma membranes of trophoblasts to become fusion competent. PMID:20861310

  7. Apicomplexans pulling the strings: manipulation of the host cell cytoskeleton dynamics.

    Science.gov (United States)

    Cardoso, Rita; Soares, Helena; Hemphill, Andrew; Leitão, Alexandre

    2016-07-01

    Invasive stages of apicomplexan parasites require a host cell to survive, proliferate and advance to the next life cycle stage. Once invasion is achieved, apicomplexans interact closely with the host cell cytoskeleton, but in many cases the different species have evolved distinct mechanisms and pathways to modulate the structural organization of cytoskeletal filaments. The host cell cytoskeleton is a complex network, largely, but not exclusively, composed of microtubules, actin microfilaments and intermediate filaments, all of which are modulated by associated proteins, and it is involved in diverse functions including maintenance of cell morphology and mechanical support, migration, signal transduction, nutrient uptake, membrane and organelle trafficking and cell division. The ability of apicomplexans to modulate the cytoskeleton to their own advantage is clearly beneficial. We here review different aspects of the interactions of apicomplexans with the three main cytoskeletal filament types, provide information on the currently known parasite effector proteins and respective host cell targets involved, and how these interactions modulate the host cell physiology. Some of these findings could provide novel targets that could be exploited for the development of preventive and/or therapeutic strategies. PMID:27041483

  8. Aspects of plant cell growth and the actin cytoskeleton: lessons from root hairs

    NARCIS (Netherlands)

    Ruijter, de N.C.A.

    1999-01-01

    The main topic the thesis addresses is the role of the actin cytoskeleton in the growth process of plant cells. Plant growth implies a combination of cell division and cell expansion. The cytoskeleton, which exists of microtubules and actin filaments, plays a major role in both processes. Before cel

  9. Effects of Mechanical Stretching on the Morphology and Cytoskeleton of Vaginal Fibroblasts from Women with Pelvic Organ Prolapse

    OpenAIRE

    Sumei Wang; Zhenyu Zhang; Dongyuan Lü; Qiuxiang Xu

    2015-01-01

    Mechanical load and postmenopausal hypoestrogen are risk factors for pelvic organ prolapse (POP). In this study, we applied a 0.1-Hz uniaxial cyclic mechanical stretching (CS) with 10% elongation and 10−8 M 17-β-estradiol to vaginal fibroblasts isolated from postmenopausal women with or without POP to investigate the effects of CS and estrogen on cell morphology and cytoskeletons of normal and POP fibroblasts. Under static culture condition, POP fibroblasts exhibited lower cell circularity an...

  10. The cytoskeleton significantly impacts invasive behavior of biological cells

    Science.gov (United States)

    Fritsch, Anatol; Käs, Josef; Seltman, Kristin; Magin, Thomas

    2014-03-01

    Cell migration is a key determinant of cancer metastasis and nerve regeneration. The role of the cytoskeleton for the epithelial-meschenymal transition (EMT), i.e, for invasive behavior of cells, is only partially understood. Here, we address this issue in cells lacking all keratins upon genome engineering. In contrast to prediction, keratin-free cells show a 60% higher deformability compared to less pronounced softening effects for actin depolymerization. To relate these findings with functional consequences, we use invasion and three-dimensional growth assays. These reveal higher invasiveness of keratin-free cells. This study supports the view that downregulation of keratins observed during EMT directly contributes to the migratory and invasive behavior of tumor cells. Cancer cells that effectively move through tissues are softer and more contractile than cells that stay local in tissues. Soft and contractile avoids jamming. Naturally, softness has to have its limits. So neuronal growth cones are too soft to carry large loads to move efficiently through scar tissue, which is required for nerve regeneration. In synopsis, the physical bounds that the functional modules of a moving cell experience in tissues may provide an overarching motif for novel approaches in diagnosis and therapy.

  11. Aspects of plant cell growth and the actin cytoskeleton: lessons from root hairs

    OpenAIRE

    Ruijter, de, A.

    1999-01-01

    The main topic the thesis addresses is the role of the actin cytoskeleton in the growth process of plant cells. Plant growth implies a combination of cell division and cell expansion. The cytoskeleton, which exists of microtubules and actin filaments, plays a major role in both processes. Before cell growth takes place, a new cell is formed by cell division. The orientation of the division plane most often predicts the orientation of cell expansion, and a correct positioning of the division p...

  12. Perturbation of host cell cytoskeleton by cranberry proanthocyanidins and their effect on enteric infections.

    Directory of Open Access Journals (Sweden)

    Kevin Harmidy

    Full Text Available Cranberry-derived compounds, including a fraction known as proanthocyanidins (PACs exhibit anti-microbial, anti-infective, and anti-adhesive properties against a number of disease-causing organisms. In this study, the effect of cranberry proanthocyanidins (CPACs on the infection of epithelial cells by two enteric bacterial pathogens, enteropathogenic Escherichia coli (EPEC and Salmonella Typhimurium was investigated. Immunofluorescence data showed that actin pedestal formation, required for infection by enteropathogenic Escherichia coli (EPEC, was disrupted in the presence of CPACs. In addition, invasion of HeLa cells by Salmonella Typhimurium was significantly reduced, as verified by gentamicin protection assay and immunofluorescence. CPACs had no effect on bacterial growth, nor any detectable effect on the production of bacterial effector proteins of the type III secretion system. Furthermore, CPACs did not affect the viability of host cells. Interestingly, we found that CPACs had a potent and dose-dependent effect on the host cell cytoskeleton that was evident even in uninfected cells. CPACs inhibited the phagocytosis of inert particles by a macrophage cell line, providing further evidence that actin-mediated host cell functions are disrupted in the presence of cranberry CPACs. Thus, although CPAC treatment inhibited Salmonella invasion and EPEC pedestal formation, our results suggest that this is likely primarily because of the perturbation of the host cell cytoskeleton by CPACs rather than an effect on bacterial virulence itself. These findings have significant implications for the interpretation of experiments on the effects of CPACs on bacteria-host cell interactions.

  13. Detachment of glycolytic enzymes from cytoskeleton of melanoma cells induced by calmodulin antagonists.

    Science.gov (United States)

    Glass-Marmor, L; Beitner, R

    1997-06-11

    Glycolysis, which is the primary energy source in cancer cells, is known to be controlled by allosteric regulators, as well as by reversible binding of glycolytic enzymes to cytoskeleton. We have previously found that different calmodulin antagonists decrease the levels of allosteric activators of glycolysis, and reduce ATP content and cell viability in B16 melanoma cells. Here we report of a novel, additional, mechanism of action of calmodulin antagonists in melanoma cells. We show that these drugs cause a detachment of the glycolytic enzymes, phosphofructokinase (ATP: D-fructose-6-phosphate 1-phosphotransferase, EC 2.7.1.11) and aldolase (D-fructose-1,6-bisphosphate D-glyceraldehyde-3-phosphate-lyase, EC 4.1.2.13), from cytoskeleton of B16 melanoma cells. This effect was dose- and time-dependent, and preceded the decrease in cell viability. The detachment of glycolytic enzymes from cytoskeleton would reduce the provision of local ATP, in the vicinity of the cytoskeleton-membrane and would affect cytoskeleton structure. Since the cytoskeleton is being recognized as an important modulator of cell function, proliferation, differentiation and neoplasia, detachment of the glycolytic enzymes from cytoskeleton induced by calmodulin antagonists, as well as their reported inhibitory action on cell proliferation, make these drugs most promising agents in treatment of cancer. PMID:9218707

  14. AMP-activated protein kinase induces actin cytoskeleton reorganization in epithelial cells

    Energy Technology Data Exchange (ETDEWEB)

    Miranda, Lisa; Carpentier, Sarah; Platek, Anna; Hussain, Nusrat; Gueuning, Marie-Agnes; Vertommen, Didier; Ozkan, Yurda; Sid, Brice; Hue, Louis; Courtoy, Pierre J.; Rider, Mark H. [de Duve Institute, Universite catholique de Louvain, Avenue Hippocrate, B-1200 Brussels (Belgium); Horman, Sandrine, E-mail: sandrine.horman@uclouvain.be [Institute of Experimental and Clinical Research - Pole of Cardiovascular Research, Universite catholique de Louvain, Avenue Hippocrate, B-1200 Brussels (Belgium)

    2010-06-04

    AMP-activated protein kinase (AMPK), a known regulator of cellular and systemic energy balance, is now recognized to control cell division, cell polarity and cell migration, all of which depend on the actin cytoskeleton. Here we report the effects of A769662, a pharmacological activator of AMPK, on cytoskeletal organization and signalling in epithelial Madin-Darby canine kidney (MDCK) cells. We show that AMPK activation induced shortening or radiation of stress fibers, uncoupling from paxillin and predominance of cortical F-actin. In parallel, Rho-kinase downstream targets, namely myosin regulatory light chain and cofilin, were phosphorylated. These effects resembled the morphological changes in MDCK cells exposed to hyperosmotic shock, which led to Ca{sup 2+}-dependent AMPK activation via calmodulin-dependent protein kinase kinase-{beta}(CaMKK{beta}), a known upstream kinase of AMPK. Indeed, hypertonicity-induced AMPK activation was markedly reduced by the STO-609 CaMKK{beta} inhibitor, as was the increase in MLC and cofilin phosphorylation. We suggest that AMPK links osmotic stress to the reorganization of the actin cytoskeleton.

  15. ARF6, PI3-kinase and host cell actin cytoskeleton in Toxoplasma gondii cell invasion

    International Nuclear Information System (INIS)

    Toxoplasma gondii infects a variety of different cell types in a range of different hosts. Host cell invasion by T. gondii occurs by active penetration of the host cell, a process previously described as independent of host actin polymerization. Also, the parasitophorous vacuole has been shown to resist fusion with endocytic and exocytic pathways of the host cell. ADP-ribosylation factor-6 (ARF6) belongs to the ARF family of small GTP-binding proteins. ARF6 regulates membrane trafficking and actin cytoskeleton rearrangements at the plasma membrane. Here, we have observed that ARF6 is recruited to the parasitophorous vacuole of tachyzoites of T. gondii RH strain and it also plays an important role in the parasite cell invasion with activation of PI3-kinase and recruitment of PIP2 and PIP3 to the parasitophorous vacuole of invading parasites. Moreover, it was verified that maintenance of host cell actin cytoskeleton integrity is important to parasite invasion.

  16. The actin Cytoskeleton in Root Hairs: a cell elongation device

    NARCIS (Netherlands)

    Ketelaar, T.; Emons, A.M.C.

    2009-01-01

    The actin cytoskeleton plays an important role in root hair development. It is involved in both the delivery of growth materials to the expanding tip of root hairs and the regulation of the area of tip growth. This review starts with a discussion of the techniques that are available to visualize the

  17. Effects of Mechanical Stretching on the Morphology and Cytoskeleton of Vaginal Fibroblasts from Women with Pelvic Organ Prolapse

    Directory of Open Access Journals (Sweden)

    Sumei Wang

    2015-04-01

    Full Text Available Mechanical load and postmenopausal hypoestrogen are risk factors for pelvic organ prolapse (POP. In this study, we applied a 0.1-Hz uniaxial cyclic mechanical stretching (CS with 10% elongation and 10−8 M 17-β-estradiol to vaginal fibroblasts isolated from postmenopausal women with or without POP to investigate the effects of CS and estrogen on cell morphology and cytoskeletons of normal and POP fibroblasts. Under static culture condition, POP fibroblasts exhibited lower cell circularity and higher relative fluorescence intensities (RFIs of F-actin, α-tubulin and vimentin. When cultured with CS, all fibroblasts grew perpendicular to the force and exhibited a decreased cell projection area, cell circularity and increased cell length/width ratio; normal fibroblasts exhibited increased RFIs of all three types of cytoskeleton, and POP fibroblasts exhibited a decreased RFI of F-actin and no significant differences of α-tubulin and vimentin. After being cultured with 17-β-estradiol and CS, normal fibroblasts no longer exhibited significant changes in the cell projection area and the RFIs of F-actin and α-tubulin; POP fibroblasts exhibited no significant changes in cell circularity, length/width ratio and F-actin even with the increased RFIs of α-tubulin and vimentin. These findings suggest that POP fibroblasts have greater sensitivity to and lower tolerance for mechanical stretching, and estrogen can improve the prognosis.

  18. Effects of mechanical stretching on the morphology and cytoskeleton of vaginal fibroblasts from women with pelvic organ prolapse.

    Science.gov (United States)

    Wang, Sumei; Zhang, Zhenyu; Lü, Dongyuan; Xu, Qiuxiang

    2015-01-01

    Mechanical load and postmenopausal hypoestrogen are risk factors for pelvic organ prolapse (POP). In this study, we applied a 0.1-Hz uniaxial cyclic mechanical stretching (CS) with 10% elongation and 10⁻⁸ M 17-β-estradiol to vaginal fibroblasts isolated from postmenopausal women with or without POP to investigate the effects of CS and estrogen on cell morphology and cytoskeletons of normal and POP fibroblasts. Under static culture condition, POP fibroblasts exhibited lower cell circularity and higher relative fluorescence intensities (RFIs) of F-actin, α-tubulin and vimentin. When cultured with CS, all fibroblasts grew perpendicular to the force and exhibited a decreased cell projection area, cell circularity and increased cell length/width ratio; normal fibroblasts exhibited increased RFIs of all three types of cytoskeleton, and POP fibroblasts exhibited a decreased RFI of F-actin and no significant differences of α-tubulin and vimentin. After being cultured with 17-β-estradiol and CS, normal fibroblasts no longer exhibited significant changes in the cell projection area and the RFIs of F-actin and α-tubulin; POP fibroblasts exhibited no significant changes in cell circularity, length/width ratio and F-actin even with the increased RFIs of α-tubulin and vimentin. These findings suggest that POP fibroblasts have greater sensitivity to and lower tolerance for mechanical stretching, and estrogen can improve the prognosis. PMID:25923074

  19. Reciprocal interactions between cell adhesion molecules of the immunoglobulin superfamily and the cytoskeleton in neurons

    Directory of Open Access Journals (Sweden)

    Vladimir eSytnyk

    2016-02-01

    Full Text Available Cell adhesion molecules of the immunoglobulin superfamily (IgSF including the neural cell adhesion molecule (NCAM and members of the L1 family of neuronal cell adhesion molecules play important functions in the developing nervous system by regulating formation, growth and branching of neurites and establishment of the synaptic contacts between neurons. In the mature brain, members of IgSF regulate synapse composition, function and plasticity required for learning and memory. The intracellular domains of IgSF cell adhesion molecules interact with the components of the cytoskeleton including the submembrane actin-spectrin meshwork, actin microfilaments, and microtubules. In this review, we summarize current data indicating that interactions between IgSF cell adhesion molecules and the cytoskeleton are reciprocal, and that while IgSF cell adhesion molecules regulate the assembly of the cytoskeleton, the cytoskeleton plays an important role in regulation of the functions of IgSF cell adhesion molecules. Reciprocal interactions between NCAM and L1 family members and the cytoskeleton and their role in neuronal differentiation and synapse formation are discussed in detail.

  20. Reciprocal Interactions between Cell Adhesion Molecules of the Immunoglobulin Superfamily and the Cytoskeleton in Neurons.

    Science.gov (United States)

    Leshchyns'ka, Iryna; Sytnyk, Vladimir

    2016-01-01

    Cell adhesion molecules of the immunoglobulin superfamily (IgSF) including the neural cell adhesion molecule (NCAM) and members of the L1 family of neuronal cell adhesion molecules play important functions in the developing nervous system by regulating formation, growth and branching of neurites, and establishment of the synaptic contacts between neurons. In the mature brain, members of IgSF regulate synapse composition, function, and plasticity required for learning and memory. The intracellular domains of IgSF cell adhesion molecules interact with the components of the cytoskeleton including the submembrane actin-spectrin meshwork, actin microfilaments, and microtubules. In this review, we summarize current data indicating that interactions between IgSF cell adhesion molecules and the cytoskeleton are reciprocal, and that while IgSF cell adhesion molecules regulate the assembly of the cytoskeleton, the cytoskeleton plays an important role in regulation of the functions of IgSF cell adhesion molecules. Reciprocal interactions between NCAM and L1 family members and the cytoskeleton and their role in neuronal differentiation and synapse formation are discussed in detail. PMID:26909348

  1. The Dynamic Pollen Tube Cytoskeleton: Live Cell Studies Using Actin-Binding and Microtubule-Binding Reporter Proteins

    Institute of Scientific and Technical Information of China (English)

    Alice Y. Cheung; Qiao-hong Duan; Silvia Santos Costa; Barend H.J.de Graaf; Veronica S.Di Stilio; Jose Feijo; Hen-Ming Wu

    2008-01-01

    Pollen tubes elongate within the pistil to transport sperm cells to the embryo sac for fertilization.Growth occurs exclusively at the tube apex,rendering pollen tube elongation a most dramatic polar cell growth process.A hall-mark pollen tube feature is its cytoskeleton,which comprises elaborately organized and dynamic actin microfilaments and microtubules.Pollen tube growth is dependent on the actin cytoskeleton;its organization and regulation have been exalined extensively by various approaches.including fluorescent protein labeled actin-binding proteins in live cell studies.Using the previously described GFP-NtADF1 and GFP-LIADF1, and a new actin reporter protein NtPLIM2b-GFP,we re-affirm that the predominant actin structures in elongating tobacco and lily pollen tubes are long,streaming actin cables along the pollen tube shank,and a subapical structure comprising shorter actin cables.The subapical collection of actin microfilaments undergoes dynamic changes,giving rise to the appearance of structures that range from basket-or funnel-shaped,mesh-like to a subtle ring.NtPLIM2b-GFP is used in combination with a guanine nucleotide exchange factor for the Rho GTPases,AtROP-GEF1,to illustrate the use of these actin reporter proteins to explore the linkage between the polar cell growth process and its actin cytoskeleton.Contrary to the actin cytoskeleton,microtubules appear not to play a direct role in supporting the polar cell growth process in angiosperm pollen tubes.Using a microtubule reporter protein based on the microtubule end-binding protein from Arabidopsis AtEB1,GFP-AtEB1,we show that the extensive microtubule network in elongating pollen tubes displays varying degrees of dynamics.These reporter proteins provide versatile tools to explore the functional connection between major structural and signaling components of the polar pollen tube growth process.

  2. Spaceflight and clinorotation cause cytoskeleton and mitochondria changes and increases in apoptosis in cultured cells

    Science.gov (United States)

    Schatten, H.; Lewis, M. L.; Chakrabarti, A.

    2001-01-01

    The cytoskeleton is a complex network of fibers that is sensitive to environmental factors including microgravity and altered gravitational forces. Cellular functions such as transport of cell organelles depend on cytoskeletal integrity; regulation of cytoskeletal activity plays a role in cell maintenance, cell division, and apoptosis. Here we report cytoskeletal and mitochondria alterations in cultured human lymphocyte (Jurkat) cells after exposure to spaceflight and in insect cells of Drosophila melanogaster (Schneider S-1) after exposure to conditions created by clinostat rotation. Jurkat cells were flown on the space shuttle in Biorack cassettes while Schneider S-1 cells were exposed to altered gravity forces as produced by clinostat rotation. The effects of both treatments were similar in the different cell types. Fifty percent of cells displayed effects on the microtubule network in both cell lines. Under these experimental conditions mitochondria clustering and morphological alterations of mitochondrial cristae was observed to various degrees after 4 and 48 hours of culture. Jurkat cells underwent cell divisions during exposure to spaceflight but a large number of apoptotic cells was also observed. Similar results were obtained in Schneider S-1 cells cultured under clinostat rotation. Both cell lines displayed mitochondria abnormalities and mitochondria clustering toward one side of the cells which is interpreted to be the result of microtubule disruption and failure of mitochondria transport along microtubules. The number of mitochondria was increased in cells exposed to altered gravity while cristae morphology was severely affected indicating altered mitochondria function. These results show that spaceflight as well as altered gravity produced by clinostat rotation affects microtubule and mitochondria organization and results in increases in apoptosis. Grant numbers: NAG 10-0224, NAG2-985. c 2001. Elsevier Science Ltd. All rights reserved.

  3. Retinoids and glucocorticoids have opposite effects on actin cytoskeleton rearrangement in hippocampal HT22 cells.

    Science.gov (United States)

    Hélène, Roumes; Julie, Brossaud; Aloïs, Lemelletier; Marie-Pierre, Moisan; Véronique, Pallet; Anabelle, Redonnet; Jean-Benoît, Corcuff

    2016-02-01

    A chronic excess of glucocorticoids elicits deleterious effects in the hippocampus. Conversely, retinoic acid plays a major role in aging brain plasticity. As synaptic plasticity depends on mechanisms related to cell morphology, we investigated the involvement of retinoic acid and glucocorticoids in the remodelling of the HT22 neurons actin cytoskeleton. Cells exhibited a significantly more elongated shape with retinoic acid and a rounder shape with dexamethasone; retinoic acid reversed the effects of dexamethasone. Actin expression and abundance were unchanged by retinoic acid or dexamethasone but F-actin organization was dramatically modified. Indeed, retinoic acid and dexamethasone increased (70 ± 7% and 176 ± 5%) cortical actin while retinoic acid suppressed the effect of dexamethasone (90 ± 6%). Retinoic acid decreased (-22 ± 9%) and dexamethasone increased (134 ± 16%) actin stress fibres. Retinoic acid also suppressed the effect of dexamethasone (-21 ± 7%). Spectrin is a key protein in the actin network remodelling. Its abundance was decreased by retinoic acid and increased by dexamethasone (-21 ± 11% and 52 ± 10%). However, retinoic acid did not modify the effect of dexamethasone (48 ± 7%). Calpain activity on spectrin was increased by retinoic acid and decreased by dexamethasone (26 ± 14% and -57 ± 5%); retinoic acid mildly but significantly modified the effect of dexamethasone (-44 ± 7%). The calpain inhibitor calpeptin suppressed the effects of retinoic acid and dexamethasone on cell shape and actin stress fibres remodelling but did not modify the effects on cortical actin. Retinoic acid and dexamethasone have a dramatic but mainly opposite effect on actin cytoskeleton remodelling. These effects originate, at least partly, from calpain activity. PMID:26748244

  4. Wdpcp, a PCP protein required for ciliogenesis, regulates directional cell migration and cell polarity by direct modulation of the actin cytoskeleton.

    Directory of Open Access Journals (Sweden)

    Cheng Cui

    2013-11-01

    Full Text Available Planar cell polarity (PCP regulates cell alignment required for collective cell movement during embryonic development. This requires PCP/PCP effector proteins, some of which also play essential roles in ciliogenesis, highlighting the long-standing question of the role of the cilium in PCP. Wdpcp, a PCP effector, was recently shown to regulate both ciliogenesis and collective cell movement, but the underlying mechanism is unknown. Here we show Wdpcp can regulate PCP by direct modulation of the actin cytoskeleton. These studies were made possible by recovery of a Wdpcp mutant mouse model. Wdpcp-deficient mice exhibit phenotypes reminiscent of Bardet-Biedl/Meckel-Gruber ciliopathy syndromes, including cardiac outflow tract and cochlea defects associated with PCP perturbation. We observed Wdpcp is localized to the transition zone, and in Wdpcp-deficient cells, Sept2, Nphp1, and Mks1 were lost from the transition zone, indicating Wdpcp is required for recruitment of proteins essential for ciliogenesis. Wdpcp is also found in the cytoplasm, where it is localized in the actin cytoskeleton and in focal adhesions. Wdpcp interacts with Sept2 and is colocalized with Sept2 in actin filaments, but in Wdpcp-deficient cells, Sept2 was lost from the actin cytoskeleton, suggesting Wdpcp is required for Sept2 recruitment to actin filaments. Significantly, organization of the actin filaments and focal contacts were markedly changed in Wdpcp-deficient cells. This was associated with decreased membrane ruffling, failure to establish cell polarity, and loss of directional cell migration. These results suggest the PCP defects in Wdpcp mutants are not caused by loss of cilia, but by direct disruption of the actin cytoskeleton. Consistent with this, Wdpcp mutant cochlea has normal kinocilia and yet exhibits PCP defects. Together, these findings provide the first evidence, to our knowledge, that a PCP component required for ciliogenesis can directly modulate the actin

  5. Regulation of T cell receptor signaling by the actin cytoskeleton and poroelastic cytoplasm

    OpenAIRE

    Beemiller, Peter; Krummel, Matthew F.

    2013-01-01

    The actin cytoskeleton plays essential roles in modulating T-cell activation. Most models of T-cell receptor (TCR) triggering, signalosome assembl, y and immune synapse formation invoke actin-dependent mechanisms. As T cells are constitutively motile cells, TCR triggering and signaling occur against a cytoskeletal backdrop that is constantly remodeling. While the interplay between actin dynamics and TCR signaling have been the focus of research for many years, much of the work in T cells has ...

  6. Cytoskeleton influence on normal and tangent fluctuation modes in the red blood cells

    CERN Document Server

    Rochal, S B

    2006-01-01

    We argue that the paradoxal softness of the red blood cells (RBC) in fluctuation spectra experiments is apparent. We show that the effective surface shear modulus $\\mu_s$ of the RBC obtained from fluctuation data and that measured in static deformation experiments have the same order of magnitude. A simple micromechanical model of the RBC developped for this purpose accounts for the influence of a finite-thickness cytoskeleton on the fluctuations of the composite membrane-cytoskeleton system. The spectrin network cytoskeleton with the bulk shear modulus estimated as $\\mu\\approx105\\div 165$ Pa contributes both to normal and tangent fluctuations of the system and confines the fluctuations of the lipid membrane. The ratio of mean square amplitudes of the RBC normal and tangent fluctuations $ /$ calculated in the frame of the model is 2-3 orders of magnitude smaller that it is in the free membrane with the same bending and shear moduli

  7. The effect of novel inhibitor of cyclin dependent kinases to cytoskeleton in higher plant cells

    Czech Academy of Sciences Publication Activity Database

    Pochylová, Žaneta; Cenklová, Věra; Strnad, Miroslav; Binarová, Pavla

    2005. [Cytoskeletální klub /13./. 27.04.2005-29.04.2005, Nové Město na Moravě] Keywords : inhibitor of cyclin dependent kinases * cytoskeleton * higher plant cells Subject RIV: EB - Genetics ; Molecular Biology

  8. Regulation of T cell receptor signaling by the actin cytoskeleton and poroelastic cytoplasm

    Science.gov (United States)

    Beemiller, Peter; Krummel, Matthew F.

    2013-01-01

    Summary The actin cytoskeleton plays essential roles in modulating T-cell activation. Most models of T-cell receptor (TCR) triggering, signalosome assembl, y and immune synapse formation invoke actin-dependent mechanisms. As T cells are constitutively motile cells, TCR triggering and signaling occur against a cytoskeletal backdrop that is constantly remodeling. While the interplay between actin dynamics and TCR signaling have been the focus of research for many years, much of the work in T cells has considered actin largely for its ‘scaffolding’ function. We examine the roles of the actin cytoskeleton in TCR signaling and immune synapse formation with an emphasis on how poroelasticity, an ensemble feature of actin dynamics with the cytosol, relates to how T cells respond to stimulation. PMID:24117819

  9. Regulation of T-cell receptor signaling by the actin cytoskeleton and poroelastic cytoplasm.

    Science.gov (United States)

    Beemiller, Peter; Krummel, Matthew F

    2013-11-01

    The actin cytoskeleton plays essential roles in modulating T-cell activation. Most models of T-cell receptor (TCR) triggering signalosome assembly and immune synapse formation invoke actin-dependent mechanisms. As T cells are constitutively motile cells, TCR triggering and signaling occur against a cytoskeletal backdrop that is constantly remodeling. While the interplay between actin dynamics and TCR signaling have been the focus of research for many years, much of the work in T cells has considered actin largely for its 'scaffolding' function. We examine the roles of the actin cytoskeleton in TCR signaling and immune synapse formation with an emphasis on how poroelasticity, an ensemble feature of actin dynamics with the cytosol, relates to how T cells respond to stimulation. PMID:24117819

  10. Microtubule cytoskeleton behavior in the initial steps of host cell invasion by Besnoitia besnoiti

    OpenAIRE

    REIS, Y; CORTES, H; VISEUMELO, L; FAZENDEIRO, I; Leitao, A.; SOARES, H

    2006-01-01

    Microtubule cytoskeleton behavior in the initial steps of host cell invasion by Besnoitia besnoiti Besnoitia besnoiti is a protozoan parasite responsible for bovine besnoitiosis. Indirect immunofluorescence showed that isolated B. besnoiti possesses a set of subpellicular microtubules, radiating from the apical end and extending for more than 2/3 of the cell body. Upon interaction with the host cell, B. besnoiti undergoes dramatic modifications of shape and surface, as revealed by atomic ...

  11. Preparing a discreet escape: Microsporidia reorganize host cytoskeleton prior to non-lytic exit from C. elegans intestinal cells.

    Science.gov (United States)

    Szumowski, Suzannah C; Estes, Kathleen A; Troemel, Emily R

    2012-10-01

    Intracellular pathogens commonly invade and replicate inside of intestinal cells and exit from these cells is a crucial step in pathogen transmission. For convenience, studies of intracellular pathogens are often conducted using in vitro cell culture systems, which unfortunately lack important features of polarized, intact intestinal epithelial cells. The nematode C. elegans provides a tractable system to study intracellular pathogens in vivo, where features of differentiated epithelial cells are easily visualized. In a recent paper, we used C. elegans as a host organism to study the exit strategy of Nematocida parisii, a naturally occurring intracellular pathogen in the microsporidia phylum. We showed that N. parisii remodels the C. elegans host cytoskeleton, and then exits host cells in an actin-dependent, non-lytic fashion. These findings illuminate key details about the transmission of microsporidia, which are poorly understood but ubiquitous pathogens. More generally, these findings have implications for exit strategies used by other intracellular pathogens that also infect epithelial cells. PMID:24058850

  12. Multiciliated cell basal bodies align in stereotypical patterns coordinated by the apical cytoskeleton.

    Science.gov (United States)

    Herawati, Elisa; Taniguchi, Daisuke; Kanoh, Hatsuho; Tateishi, Kazuhiro; Ishihara, Shuji; Tsukita, Sachiko

    2016-08-29

    Multiciliated cells (MCCs) promote fluid flow through coordinated ciliary beating, which requires properly organized basal bodies (BBs). Airway MCCs have large numbers of BBs, which are uniformly oriented and, as we show here, align linearly. The mechanism for BB alignment is unexplored. To study this mechanism, we developed a long-term and high-resolution live-imaging system and used it to observe green fluorescent protein-centrin2-labeled BBs in cultured mouse tracheal MCCs. During MCC differentiation, the BB array adopted four stereotypical patterns, from a clustering "floret" pattern to the linear "alignment." This alignment process was correlated with BB orientations, revealed by double immunostaining for BBs and their asymmetrically associated basal feet (BF). The BB alignment was disrupted by disturbing apical microtubules with nocodazole and by a BF-depleting Odf2 mutation. We constructed a theoretical model, which indicated that the apical cytoskeleton, acting like a viscoelastic fluid, provides a self-organizing mechanism in tracheal MCCs to align BBs linearly for mucociliary transport. PMID:27573463

  13. Live cell tracking of symmetry break in actin cytoskeleton triggered by abrupt changes in micromechanical environments.

    Science.gov (United States)

    Inoue, S; Frank, V; Hörning, M; Kaufmann, S; Yoshikawa, H Y; Madsen, J P; Lewis, A L; Armes, S P; Tanaka, M

    2015-12-01

    With the aid of stimulus-responsive hydrogel substrates composed of ABA triblock copolymer micelles, we monitored the morphological dynamics of myoblast (C2C12) cells in response to an abrupt change in the substrate elasticity by live cell imaging. The remodeling of actin cytoskeletons could be monitored by means of transient transfection with LifeAct-GFP. Dynamic changes in the orientational order of actin filaments were characterized by an order parameter, which enables one to generalize the mechanically induced actin cytoskeletons as a break of symmetry. The critical role that acto-myosin complexes play in the morphological transition was verified by the treatment of cells with myosin II inhibitor (blebbistatin) and the fluorescence localization of focal adhesion contacts. Such dynamically tunable hydrogels can be utilized as in vitro cellular micro-environments that can exert time-dependent stimuli to mechanically regulate target cells. PMID:26347909

  14. Ornithine decarboxylase and extracellular polyamines regulate microvascular sprouting and actin cytoskeleton dynamics in endothelial cells

    International Nuclear Information System (INIS)

    The polyamines are essential for cancer cell proliferation during tumorigenesis. Targeted inhibition of ornithine decarboxylase (ODC), i.e. a key enzyme of polyamine biosynthesis, by α-difluoromethylornithine (DFMO) has shown anti-neoplastic activity in various experimental models. This activity has mainly been attributed to the anti-proliferative effect of DFMO in cancer cells. Here, we provide evidence that unperturbed ODC activity is a requirement for proper microvessel sprouting ex vivo as well as the migration of primary human endothelial cells. DFMO-mediated ODC inhibition was reversed by extracellular polyamine supplementation, showing that anti-angiogenic effects of DFMO were specifically related to polyamine levels. ODC inhibition was associated with an abnormal morphology of the actin cytoskeleton during cell spreading and migration. Moreover, our data suggest that de-regulated actin cytoskeleton dynamics in DFMO treated endothelial cells may be related to constitutive activation of the small GTPase CDC42, i.e. a well-known regulator of cell motility and actin cytoskeleton remodeling. These insights into the potential role of polyamines in angiogenesis should stimulate further studies testing the combined anti-tumor effect of polyamine inhibition and established anti-angiogenic therapies in vivo.

  15. Stiffening of Red Blood Cells Induced by Disordered Cytoskeleton Structures: A Joint Theory-experiment Study

    CERN Document Server

    Lai, Lipeng; Lim, Chwee Teck; Cao, Jianshu

    2015-01-01

    The functions and elasticities of the cell are largely related to the structures of the cytoskeletons underlying the lipid bi-layer. Among various cell types, the Red Blood Cell (RBC) possesses a relatively simple cytoskeletal structure. Underneath the membrane, the RBC cytoskeleton takes the form of a two dimensional triangular network, consisting of nodes of actins (and other proteins) and edges of spectrins. Recent experiments focusing on the malaria infected RBCs (iRBCs) showed that there is a correlation between the elongation of spectrins in the cytoskeletal network and the stiffening of the iRBCs. Here we rationalize the correlation between these two observations by combining the worm-like chain (WLC) model for single spectrins and the Effective Medium Theory (EMT) for the network elasticity. We specifically focus on how the disorders in the cytoskeletal network affect its macroscopic elasticity. Analytical and numerical solutions from our model reveal that the stiffness of the membrane increases with ...

  16. Adaptive rheology and ordering of cell cytoskeleton govern matrix rigidity sensing

    Science.gov (United States)

    Gupta, Mukund; Sarangi, Bibhu Ranjan; Deschamps, Joran; Nematbakhsh, Yasaman; Callan-Jones, Andrew; Margadant, Felix; Mège, René-Marc; Lim, Chwee Teck; Voituriez, Raphaël; Ladoux, Benoît

    2015-06-01

    Matrix rigidity sensing regulates a large variety of cellular processes and has important implications for tissue development and disease. However, how cells probe matrix rigidity, and hence respond to it, remains unclear. Here, we show that rigidity sensing and adaptation emerge naturally from actin cytoskeleton remodelling. Our in vitro experiments and theoretical modelling demonstrate a biphasic rheology of the actin cytoskeleton, which transitions from fluid on soft substrates to solid on stiffer ones. Furthermore, we find that increasing substrate stiffness correlates with the emergence of an orientational order in actin stress fibres, which exhibit an isotropic to nematic transition that we characterize quantitatively in the framework of active matter theory. These findings imply mechanisms mediated by a large-scale reinforcement of actin structures under stress, which could be the mechanical drivers of substrate stiffness-dependent cell shape changes and cell polarity.

  17. Calponin 3 Regulates Actin Cytoskeleton Rearrangement in Trophoblastic Cell Fusion

    OpenAIRE

    Shibukawa, Yukinao; Yamazaki, Natsuko; Kumasawa, Keiichi; Daimon, Etsuko; Tajiri, Michiko; Okada, Yuka; Ikawa, Masahito; Wada, Yoshinao

    2010-01-01

    Cell–cell fusion is an intriguing differentiation process, essential for placental development and maturation. A proteomic approach identified a cytoplasmic protein, calponin 3 (CNN3), related to the fusion of BeWo choriocarcinoma cells. CNN3 was expressed in cytotrophoblasts in human placenta. CNN3 gene knockdown promoted actin cytoskeletal rearrangement and syncytium formation in BeWo cells, suggesting CNN3 to be a negative regulator of trophoblast fusion. Indeed, CNN3 depletion promoted Be...

  18. Simulated weightlessness changes the cytoskeleton and extracellular matrix proteins in papillary thyroid carcinoma cells.

    Science.gov (United States)

    Infanger, Manfred; Kossmehl, Peter; Shakibaei, Mehdi; Bauer, Johann; Kossmehl-Zorn, Stephanie; Cogoli, Augusto; Curcio, Francesco; Oksche, Alexander; Wehland, Markus; Kreutz, Reinhold; Paul, Martin; Grimm, Daniela

    2006-05-01

    Studies of astronauts, experimental animals, and cells have shown that, after spaceflights, the function of the thyroid is altered by low-gravity conditions. The objective of this study was to investigate the cytoskeleton and extracellular matrix (ECM) protein synthesis of papillary thyroid cancer cells grown under zero g. We investigated alterations of ONCO-DG 1 cells exposed to simulated microgravity on a three-dimensional random-positioning machine (clinostat) for 30 min, 24 h, 48 h, 72 h, and 120 h (n=6, each group). ONCO-DG 1 cells grown under microgravity exhibited early alterations of the cytoskeleton and formed multicellular spheroids. The cytoskeleton was disintegrated, and nuclei showed morphological signs of apoptosis after 30 min. At this time, vimentin was increased. Vimentin and cytokeratin were highly disorganized, and microtubules (alpha-tubulin) did not display their typical radial array. After 48 h, the cytoskeletal changes were nearly reversed. The formation of multicellular spheroids continued. In parallel, the accumulation of ECM components, such as collagen types I and III, fibronectin, chondroitin sulfate, osteopontin, and CD44, increased. The levels of both transforming growth factor beta-1 (TGF-beta(1)) and TGF-beta receptor type II proteins were elevated from 24 h until 120 h clinorotation. Gene expression of TGF-beta(1) was clearly enhanced during culture under zero g. The amount of E-cadherin was enhanced time-dependently. We suggest that simulated weightlessness rapidly affects the cytoskeleton of papillary thyroid carcinoma cells and increases the amount of ECM proteins in a time-dependent manner. PMID:16432709

  19. Stem cell cytoskeleton is slaved to active motors

    Science.gov (United States)

    Rehfeldt, Florian; Brown, Andre; Engler, Adam; Discher, Dennis

    2007-03-01

    Cells feel their physical microenvironment through their adhesion and respond to it in various ways. Indeed, matrix elasticity can even guide the differentiation of human adult mesenchymal stem cells (MSCs) [Engler et al. Cell 2006]. Sparse cultures of MSCs on elastic collagen--coated substrates that are respectively soft, stiff, or extremely stiff were shown to induce neurogenesis, myogenesis, and osteogenesis. Lineage commitment was evaluated by morphological analysis, protein expression profiles, and transcription microarrays. Differentiation could be completely blocked with a specific non-muscle myosin II (NMM II) inhibitor, suggesting that contractile motor activity is essential for the cells to sense matrix elasticity. Current studies by AFM and near-field fluorescence imaging show that NMM II inhibition in stem cells on rigid glass surfaces promotes actin-rich dendritic outgrowth resembling neurite extension. Dynamic cell studies have been conducted to elucidate the complex molecular interplay of the contractile apparatus in response to selected physical and biochemical stimuli. Additional insight is being gained by using AFM to investigate the local elasticity of the cell's cytoskeletal force sensing machinery.

  20. Live cell imaging of membrane / cytoskeleton interactions and membrane topology

    Science.gov (United States)

    Chierico, Luca; Joseph, Adrian S.; Lewis, Andrew L.; Battaglia, Giuseppe

    2014-09-01

    We elucidate the interaction between actin and specific membrane components, using real time live cell imaging, by delivering probes that enable access to components, that cannot be accessed genetically. We initially investigated the close interplay between Phosphatidylinositol 4,5-bisphosphate (PIP2) and the F-actin network. We show that, during the early stage of cell adhesion, PIP2 forms domains within the filopodia membrane. We studied these domains alongside cell spreading and observed that these very closely follow the actin tread-milling. We show that this mechanism is associated with an active transport of PIP2 rich organelles from the cell perinuclear area to the edge, along actin fibers. Finally, mapping other phospholipids and membrane components we observed that the PIP2 domains formation is correlated with sphingosine and cholesterol rafts.

  1. Form-finding of complex tensegrity structures: application to cell cytoskeleton modelling

    Science.gov (United States)

    Baudriller, Haïmad; Maurin, Bernard; Cañadas, Patrick; Montcourrier, Philippe; Parmeggiani, Andrea; Bettache, Nadir

    2006-11-01

    The ability to model the mechanical behaviour of the cell cytoskeleton as realistically as possible is a key point in understanding numerous biological mechanisms. Tensegrity systems have already demonstrated their pertinence for this purpose. However, the structures considered until now are based only on models with simplified geometry and topology compared to the true complexity of cytoskeleton architecture. The aim of this Note is to propose a form-finding method for generating nonregular tensegrity shapes of higher diversity and complexity. The process relies on the use of the dynamic relaxation method. Further improvements have made it possible to control the computed morphologies and to modify them to approach experimentally observed configurations. Various examples illustrate the use of the method and the results obtained for different cell typologies. To cite this article: H. Baudriller et al., C. R. Mecanique 334 (2006).

  2. Tether Extrusion from Red Blood Cells: Integral Proteins Unbinding from Cytoskeleton

    OpenAIRE

    Borghi, N.; Brochard-Wyart, F.

    2007-01-01

    We investigate the mechanical strength of adhesion and the dynamics of detachment of the membrane from the cytoskeleton of red blood cells (RBCs). Using hydrodynamical flows, we extract membrane tethers from RBCs locally attached to the tip of a microneedle. We monitor their extrusion and retraction dynamics versus flow velocity (i.e., extrusion force) over successive extrusion-retraction cycles. Membrane tether extrusion is carried out on healthy RBCs and ATP-depleted or -inhibited RBCs. For...

  3. Near-Critical Fluctuations and Cytoskeleton-Assisted Phase Separation Lead to Subdiffusion in Cell Membranes

    OpenAIRE

    Ehrig, Jens; Petrov, Eugene P.; Schwille, Petra

    2011-01-01

    We address the relationship between membrane microheterogeneity and anomalous subdiffusion in cell membranes by carrying out Monte Carlo simulations of two-component lipid membranes. We find that near-critical fluctuations in the membrane lead to transient subdiffusion, while membrane-cytoskeleton interaction strongly affects phase separation, enhances subdiffusion, and eventually leads to hop diffusion of lipids. Thus, we present a minimum realistic model for membrane rafts showing the featu...

  4. Oxytocin receptor ligands induce changes in cytoskeleton in neuroblastoma cells.

    Science.gov (United States)

    Bakos, Jan; Strbak, Vladimir; Paulikova, Helena; Krajnakova, Lucia; Lestanova, Zuzana; Bacova, Zuzana

    2013-07-01

    Aim of the present study was to evaluate effects of ligands of oxytocin receptors on gene expression of neurofilament proteins (nestin and microtubule-associated protein 2 (MAP2)) associated with neuronal differentiation and growth factors (brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF)) related to neuronal growth. Fluorescent staining of F-actin was used to observe morphology of cells. Co-treatment with oxytocin and oxytocin receptor antagonist--atosiban--resulted in significant increase of MAP2 gene expression in SK-N-SH cells. There was no effect of oxytocin on gene expression of growth factors BDNF and NGF. Surprisingly, oxytocin with atosiban significantly increased mRNA levels for both BDNF and NGF. Gene expression of vasopressin receptor (V1aR) significantly decreased in response to vasopressin. Atosiban decreased mRNA levels for oxytocin receptor (OXTR) and V1aR. Oxytocin significantly decreased OXTR and nestin mRNA levels and increased mRNA levels for BDNF and NGF in U-87 MG cells. The densest recruitment of F-actin filaments was observed in apical parts of filopodia in SK-N-SH cells incubated in oxytocin presence. Present data demonstrate complex role of ligands of oxytocin receptors in regulation of gene expression of intermediate filaments and thus, oxytocin might be considered as a growth factor in neuronal type of cells. PMID:23335033

  5. Decoding Cytoskeleton-Anchored and Non-Anchored Receptors from Single-Cell Adhesion Force Data.

    Science.gov (United States)

    Sariisik, Ediz; Popov, Cvetan; Müller, Jochen P; Docheva, Denitsa; Clausen-Schaumann, Hauke; Benoit, Martin

    2015-10-01

    Complementary to parameters established for cell-adhesion force curve analysis, we evaluated the slope before a force step together with the distance from the surface at which the step occurs and visualized the result in a two-dimensional density plot. This new tool allows detachment steps of long membrane tethers to be distinguished from shorter jumplike force steps, which are typical for cytoskeleton-anchored bonds. A prostate cancer cell line (PC3) immobilized on an atomic-force-microscopy sensor interacted with three different substrates: collagen-I (Col-I), bovine serum albumin, and a monolayer of bone marrow-derived stem cells (SCP1). To address PC3 cells' predominant Col-I binding molecules, an antibody-blocking β1-integrin was used. Untreated PC3 cells on Col-I or SCP1 cells, which express Col-I, predominantly showed jumps in their force curves, while PC3 cells on bovine-serum-albumin- and antibody-treated PC3 cells showed long membrane tethers. The probability density plots thus revealed that β1-integrin-specific interactions are predominately anchored to the cytoskeleton, while the nonspecific interactions are mainly membrane-anchored. Experiments with latrunculin-A-treated PC3 cells corroborated these observations. The plots thus reveal details of the anchoring of bonds to the cell and provide a better understanding of receptor-ligand interactions. PMID:26445433

  6. Fullerenol cytotoxicity in kidney cells is associated with cytoskeleton disruption, autophagic vacuole accumulation, and mitochondrial dysfunction

    International Nuclear Information System (INIS)

    Water soluble fullerenes, such as the hydroxylated fullerene, fullerenol (C60OHx), are currently under development for diagnostic and therapeutic biomedical applications in the field of nanotechnology. These molecules have been shown to undergo urinary clearance, yet there is limited data available on their renal biocompatibility. Here we examine the biological responses of renal proximal tubule cells (LLC-PK1) exposed to fullerenol. Fullerenol was found to be cytotoxic in the millimolar range, with viability assessed by the sulforhodamine B and trypan blue assays. Fullerenol-induced cell death was associated with cytoskeleton disruption and autophagic vacuole accumulation. Interaction with the autophagy pathway was evaluated in vitro by Lysotracker Red dye uptake, LC3-II marker expression and TEM. Fullerenol treatment also resulted in coincident loss of cellular mitochondrial membrane potential and ATP depletion, as measured by the Mitotracker Red dye and the luciferin-luciferase assays, respectively. Fullerenol-induced ATP depletion and loss of mitochondrial potential were partially ameliorated by co-treatment with the autophagy inhibitor, 3-methyladenine. In vitro fullerenol treatment did not result in appreciable oxidative stress, as measured by lipid peroxide and glutathione content. Based on these data, it is hypothesized that cytoskeleton disruption may be an initiating event in fullerenol cytotoxicity, leading to subsequent autophagy dysfunction and loss of mitochondrial capacity. As nanoparticle-induced cytoskeleton disruption, autophagic vacuole accumulation and mitochondrial dysfunction are commonly reported in the literature, the proposed mechanism may be relevant for a variety of nanomaterials.

  7. Role of cytoskeleton network in anisosmotic volume changes of intact and permeabilized A549 cells.

    Science.gov (United States)

    Platonova, Alexandra; Ponomarchuk, Olga; Boudreault, Francis; Kapilevich, Leonid V; Maksimov, Georgy V; Grygorczyk, Ryszard; Orlov, Sergei N

    2015-10-01

    Recently we found that cytoplasm of permeabilized mammalian cells behaves as a hydrogel displaying intrinsic osmosensitivity. This study examined the role of microfilaments and microtubules in the regulation of hydrogel osmosensitivity, volume-sensitive ion transporters, and their contribution to volume modulation of intact cells. We found that intact and digitonin-permeabilized A549 cells displayed similar rate of shrinkage triggered by hyperosmotic medium. It was significantly slowed-down in both cell preparations after disruption of actin microfilaments by cytochalasin B, suggesting that rapid water release by intact cytoplasmic hydrogel contributes to hyperosmotic shrinkage. In hyposmotic swelling experiments, disruption of microtubules by vinblastine attenuated the maximal amplitude of swelling in intact cells and completely abolished it in permeabilized cells. The swelling of intact cells also triggered ~10-fold elevation of furosemide-resistant (86)Rb+ (K+) permeability and the regulatory volume decrease (RVD), both of which were abolished by Ba2+. Interestingly, RVD and K+ permeability remained unaffected in cytocholasin/vinblastine treated cells demonstrating that cytoskeleton disruption has no direct impact on Ba2+-sensitive K+-channels involved in RVD. Our results show, for the first time, that the cytoskeleton network contributes directly to passive cell volume adjustments in anisosmotic media via the modulation of the water retained by the cytoplasmic hydrogel. PMID:26171817

  8. Impact of Simulated Microgravity on Cytoskeleton and Viscoelastic Properties of Endothelial Cell.

    Science.gov (United States)

    Janmaleki, M; Pachenari, M; Seyedpour, S M; Shahghadami, R; Sanati-Nezhad, A

    2016-01-01

    This study focused on the effects of simulated microgravity (s-μg) on mechanical properties, major cytoskeleton biopolymers, and morphology of endothelial cells (ECs). The structural and functional integrity of ECs are vital to regulate vascular homeostasis and prevent atherosclerosis. Furthermore, these highly gravity sensitive cells play a key role in pathogenesis of many diseases. In this research, impacts of s-μg on mechanical behavior of human umbilical vein endothelial cells were investigated by utilizing a three-dimensional random positioning machine (3D-RPM). Results revealed a considerable drop in cell stiffness and viscosity after 24 hrs of being subjected to weightlessness. Cortical rigidity experienced relatively immediate and significant decline comparing to the stiffness of whole cell body. The cells became rounded in morphology while western blot analysis showed reduction of the main cytoskeletal components. Moreover, fluorescence staining confirmed disorganization of both actin filaments and microtubules (MTs). The results were compared statistically among test and control groups and it was concluded that s-μg led to a significant alteration in mechanical behavior of ECs due to remodeling of cell cytoskeleton. PMID:27581365

  9. Dynamic Regulation of Activated Leukocyte Cell Adhesion Molecule–mediated Homotypic Cell Adhesion through the Actin CytoskeletonV⃞

    OpenAIRE

    Nelissen, Judith M. D. T.; Peters, Inge M.; de Grooth, Bart G.; Van Kooyk, Yvette; Figdor, Carl G.

    2000-01-01

    Restricted expression of activated leukocyte cell adhesion molecule (ALCAM) by hematopoietic cells suggests an important role in the immune system and hematopoiesis. To get insight into the mechanisms that control ALCAM-mediated adhesion we have investigated homotypic ALCAM–ALCAM interactions. Here, we demonstrate that the cytoskeleton regulates ALCAM-mediated cell adhesion because inhibition of actin polymerization by cytochalasin D (CytD) strongly induces homotypic ALCAM–ALCAM interactions....

  10. Ethanol exposure disrupts extraembryonic microtubule cytoskeleton and embryonic blastomere cell adhesion, producing epiboly and gastrulation defects

    Directory of Open Access Journals (Sweden)

    Swapnalee Sarmah

    2013-08-01

    Fetal alcohol spectrum disorder (FASD occurs when pregnant mothers consume alcohol, causing embryonic ethanol exposure and characteristic birth defects that include craniofacial, neural and cardiac defects. Gastrulation is a particularly sensitive developmental stage for teratogen exposure, and zebrafish is an outstanding model to study gastrulation and FASD. Epiboly (spreading blastomere cells over the yolk cell, prechordal plate migration and convergence/extension cell movements are sensitive to early ethanol exposure. Here, experiments are presented that characterize mechanisms of ethanol toxicity on epiboly and gastrulation. Epiboly mechanisms include blastomere radial intercalation cell movements and yolk cell microtubule cytoskeleton pulling the embryo to the vegetal pole. Both of these processes were disrupted by ethanol exposure. Ethanol effects on cell migration also indicated that cell adhesion was affected, which was confirmed by cell aggregation assays. E-cadherin cell adhesion molecule expression was not affected by ethanol exposure, but E-cadherin distribution, which controls epiboly and gastrulation, was changed. E-cadherin was redistributed into cytoplasmic aggregates in blastomeres and dramatically redistributed in the extraembryonic yolk cell. Gene expression microarray analysis was used to identify potential causative factors for early development defects, and expression of the cell adhesion molecule protocadherin-18a (pcdh18a, which controls epiboly, was significantly reduced in ethanol exposed embryos. Injecting pcdh18a synthetic mRNA in ethanol treated embryos partially rescued epiboly cell movements, including enveloping layer cell shape changes. Together, data show that epiboly and gastrulation defects induced by ethanol are multifactorial, and include yolk cell (extraembryonic tissue microtubule cytoskeleton disruption and blastomere adhesion defects, in part caused by reduced pcdh18a expression.

  11. Mechanical principle of enhancing cell-substrate adhesion via pre-tension in the cytoskeleton.

    Science.gov (United States)

    Chen, Bin; Gao, Huajian

    2010-05-19

    Motivated by our earlier study on the effect of pre-tension in gecko adhesion, here we investigate whether and how pre-tension in cytoskeleton influences cell adhesion by developing a stochastic-elasticity model of a stress fiber attached on a rigid substrate via molecular bonds. By comparing the variations in adhesion lifetime and observing the sequences of bond breaking with and without pre-tension in the stress fiber under the same applied force, we demonstrate that the effect of pre-tension is to shift the interfacial failure mode from cracklike propagation toward uniform bond failure within the contact region, thereby greatly increasing the adhesion lifetime. Since stress fibers are the primary load-bearing components of cells, as well as the basic functional units of cytoskeleton that facilitate cell adhesion, this study suggests a feasible mechanism by which cell adhesion could be actively controlled via cytoskeletal contractility and proposes that pre-tension may be a general principle in biological adhesion. PMID:20483323

  12. Mechanical Principle of Enhancing Cell-Substrate Adhesion via Pre-Tension in the Cytoskeleton

    OpenAIRE

    Chen, Bin; Gao, Huajian

    2010-01-01

    Motivated by our earlier study on the effect of pre-tension in gecko adhesion, here we investigate whether and how pre-tension in cytoskeleton influences cell adhesion by developing a stochastic-elasticity model of a stress fiber attached on a rigid substrate via molecular bonds. By comparing the variations in adhesion lifetime and observing the sequences of bond breaking with and without pre-tension in the stress fiber under the same applied force, we demonstrate that the effect of pre-tensi...

  13. Plasma membrane and cytoskeleton dynamics during single-cell wound healing.

    Science.gov (United States)

    Boucher, Eric; Mandato, Craig A

    2015-10-01

    Wounding leads not only to plasma membrane disruption, but also to compromised cytoskeleton structures. This results not only in unwarranted exchanges between the cytosol and extracellular milieu, but also in loss of tensegrity, which may further endanger the cell. Tensegrity can be described as the interplay between the tensile forces generated by the apparent membrane tension, actomyosin contraction, and the cytoskeletal structures resisting those changes (e.g., microtubules). It is responsible for the structural integrity of the cell and for its ability to sense mechanical signals. Recent reviews dealing with single-cell healing mostly focused on the molecular machineries controlling the traffic and fusion of specific vesicles, or their role in different pathologies. In this review, we aim to take a broader view of the different modes of single cell repair, while focussing on the different ways the changes in plasmalemma surface area and composition, plasmalemma tension, and cytoskeletal dynamics may influence and affect single-cell repair. PMID:26209916

  14. Stiffening of Red Blood Cells Induced by Cytoskeleton Disorders: A Joint Theory-Experiment Study.

    Science.gov (United States)

    Lai, Lipeng; Xu, Xiaofeng; Lim, Chwee Teck; Cao, Jianshu

    2015-12-01

    The functions and elasticities of the cell are largely related to the structures of the cytoskeletons underlying the lipid bilayer. Among various cell types, the red blood cell (RBC) possesses a relatively simple cytoskeletal structure. Underneath the membrane, the RBC cytoskeleton takes the form of a two-dimensional triangular network, consisting of nodes of actins (and other proteins) and edges of spectrins. Recent experiments focusing on the malaria-infected RBCs (iRBCs) show that there is a correlation between the elongation of spectrins in the cytoskeletal network and the stiffening of the iRBCs. Here we rationalize the correlation between these two observations by combining the wormlike chain model for single spectrins and the effective medium theory for the network elasticity. We specifically focus on how the disorders in the cytoskeletal network affect its macroscopic elasticity. Analytical and numerical solutions from our model reveal that the stiffness of the membrane increases with increasing end-to-end distances of spectrins, but has a nonmonotonic dependence on the variance of the end-to-end distance distributions. These predictions are verified quantitatively by our atomic force microscopy and micropipette aspiration measurements of iRBCs. The model may, from a molecular level, provide guidelines for future identification of new treatment methods for RBC-related diseases, such as malaria infection. PMID:26636940

  15. Effects of altered gravity on the cell cycle, actin cytoskeleton and proteome in Physarum polycephalum

    Science.gov (United States)

    He, Jie; Zhang, Xiaoxian; Gao, Yong; Li, Shuijie; Sun, Yeqing

    Some researchers suggest that the changes of cell cycle under the effect of microgravity may be associated with many serious adverse physiological changes. In the search for underlying mechanisms and possible new countermeasures, we used the slime mold Physarum polycephalum in which all the nuclei traverse the cell cycle in natural synchrony to study the effects of altered gravity on the cell cycle, actin cytoskeleton and proteome. In parallel, the cell cycle was analyzed in Physarum incubated (1) in altered gravity for 20 h, (2) in altered gravity for 40 h, (3) in altered gravity for 80 h, and (4) in ground controls. The cell cycle, the actin cytoskeleton, and proteome in the altered gravity and ground controls were examined. The results indicated that the duration of the G2 phase was lengthened 20 min in high aspect ratio vessel (HARV) for 20 h, and prolonged 2 h in altered gravity either for 40 h or for 80 h, whereas the duration of other phases in the cell cycle was unchanged with respect to the control. The microfilaments in G2 phase had a reduced number of fibers and a unique abnormal morphology in altered gravity for 40 h, whereas the microfilaments in other phases of cell cycle were unchanged when compared to controls. Employing classical two-dimensional electrophoresis (2-DE), we examined the effect of the altered gravity on P. polycephalum proteins. The increase in the duration of G2 phase in altered gravity for 40 h was accompanied by changes in the 2-DE protein profiles, over controls. Out of a total of 200 protein spots investigated in G2 phase, which were reproducible in repeated experiments, 72 protein spots were visually identified as specially expressed, and 11 proteins were up-regulated by 2-fold and 28 proteins were down-regulated by 2-fold over controls. Out of a total of three low-expressed proteins in G2 phase in altered gravity for 40 h, two proteins were unknown proteins, and one protein was spherulin 3b by MALDI-TOF mass spectrometry (MS

  16. Tumor metastatic promoter ABCE1 interacts with the cytoskeleton protein actin and increases cell motility.

    Science.gov (United States)

    Han, Xu; Tian, Ye; Tian, Dali

    2016-06-01

    ABCE1, a member of the ATP-binding cassette (ABC) family, is a candidate tumor metastatic promoter in lung cancer. Overexpression of ABCE1 is correlated with aggressive growth and metastasis in lung cancer cells. However, the exact mechanism remains unclear. In the present study, GST pull-down assay provided evidence of the possible interaction between ABCE1 and β-actin using GST-ABCE1 as a bait protein. Co-immunoprecipitation manifested ABCE1 formed complexes with β-actin in vivo. ABCE1 overexpression significantly increased the migration of lung cancer cells which may be attributed to the promotion of F-actin rearrangements. Taken together, these data suggest that overexpression of ABCE1 produces an obvious effect on the motility of lung cancer cells through cytoskeleton rearrangement. PMID:27109616

  17. MiR-221 influences effector functions and actin cytoskeleton in mast cells.

    Directory of Open Access Journals (Sweden)

    Ramon J Mayoral

    Full Text Available Mast cells have essential effector and immunoregulatory functions in IgE-associated allergic disorders and certain innate and adaptive immune responses, but the role of miRNAs in regulating mast cell functions is almost completely unexplored. To examine the role of the activation-induced miRNA miR-221 in mouse mast cells, we developed robust lentiviral systems for miRNA overexpression and depletion. While miR-221 favored mast cell adhesion and migration towards SCF or antigen in trans-well migration assays, as well as cytokine production and degranulation in response to IgE-antigen complexes, neither miR-221 overexpression, nor its ablation, interfered with mast cell differentiation. Transcriptional profiling of miR-221-overexpressing mast cells revealed modulation of many transcripts, including several associated with the cytoskeleton; indeed, miR-221 overexpression was associated with reproducible increases in cortical actin in mast cells, and with altered cellular shape and cell cycle in murine fibroblasts. Our bioinformatics analysis showed that this effect was likely mediated by the composite effect of miR-221 on many primary and secondary targets in resting cells. Indeed, miR-221-induced cellular alterations could not be recapitulated by knockdown of one of the major targets of miR-221. We propose a model in which miR-221 has two different roles in mast cells: in resting cells, basal levels of miR-221 contribute to the regulation of the cell cycle and cytoskeleton, a general mechanism probably common to other miR-221-expressing cell types, such as fibroblasts. Vice versa, upon induction in response to mast cell stimulation, miR-221 effects are mast cell-specific and activation-dependent, contributing to the regulation of degranulation, cytokine production and cell adherence. Our studies provide new insights into the roles of miR-221 in mast cell biology, and identify novel mechanisms that may contribute to mast cell-related pathological

  18. Actin Cytoskeleton and Golgi Involvement in Barley stripe mosaic virus Movement and Cell Wall Localization of Triple Gene Block Proteins

    Directory of Open Access Journals (Sweden)

    Hyoun-Sub Lim

    2013-03-01

    Full Text Available Barley stripe mosaic virus (BSMV induces massive actin filament thickening at the infection front of infected Nicotiana benthamiana leaves. To determine the mechanisms leading to actin remodeling, fluorescent protein fusions of the BSMV triple gene block (TGB proteins were coexpressed in cells with the actin marker DsRed: Talin. TGB ectopic expression experiments revealed that TGB3 is a major elicitor of filament thickening, that TGB2 resulted in formation of intermediate DsRed:Talin filaments, and that TGB1 alone had no obvious effects on actin filament structure. Latrunculin B (LatB treatments retarded BSMV cell-to-cell movement, disrupted actin filament organization, and dramatically decreased the proportion of paired TGB3 foci appearing at the cell wall (CW. BSMV infection of transgenic plants tagged with GFP-KDEL exhibited membrane proliferation and vesicle formation that were especially evident around the nucleus. Similar membrane proliferation occurred in plants expressing TGB2 and/or TGB3, and DsRed: Talin fluorescence in these plants colocalized with the ER vesicles. TGB3 also associated with the Golgi apparatus and overlapped with cortical vesicles appearing at the cell periphery. Brefeldin A treatments disrupted Golgi and also altered vesicles at the CW, but failed to interfere with TGB CW localization. Our results indicate that actin cytoskeleton interactions are important in BSMV cell-to-cell movement and for CW localization of TGB3.

  19. Molecular model of the microvillar cytoskeleton and organization of the brush border.

    Directory of Open Access Journals (Sweden)

    Jeffrey W Brown

    Full Text Available BACKGROUND: Brush border microvilli are approximately 1-microm long finger-like projections emanating from the apical surfaces of certain, specialized absorptive epithelial cells. A highly symmetric hexagonal array of thousands of these uniformly sized structures form the brush border, which in addition to aiding in nutrient absorption also defends the large surface area against pathogens. Here, we present a molecular model of the protein cytoskeleton responsible for this dramatic cellular morphology. METHODOLOGY/PRINCIPAL FINDINGS: The model is constructed from published crystallographic and microscopic structures reported by several groups over the last 30+ years. Our efforts resulted in a single, unique, self-consistent arrangement of actin, fimbrin, villin, brush border myosin (Myo1A, calmodulin, and brush border spectrin. The central actin core bundle that supports the microvillus is nearly saturated with fimbrin and villin cross-linkers and has a density similar to that found in protein crystals. The proposed model accounts for all major proteinaceous components, reproduces the experimentally determined stoichiometry, and is consistent with the size and morphology of the biological brush border membrane. CONCLUSIONS/SIGNIFICANCE: The model presented here will serve as a structural framework to explain many of the dynamic cellular processes occurring over several time scales, such as protein diffusion, association, and turnover, lipid raft sorting, membrane deformation, cytoskeletal-membrane interactions, and even effacement of the brush border by invading pathogens. In addition, this model provides a structural basis for evaluating the equilibrium processes that result in the uniform size and structure of the highly dynamic microvilli.

  20. Radiation Effects on the Cytoskeleton of Endothelial Cells and Endothelial Monolayer Permeability

    International Nuclear Information System (INIS)

    Purpose: To investigate the effects of radiation on the endothelial cytoskeleton and endothelial monolayer permeability and to evaluate associated signaling pathways, which could reveal potential mechanisms of known vascular effects of radiation. Methods and Materials: Cultured endothelial cells were X-ray irradiated, and actin filaments, microtubules, intermediate filaments, and vascular endothelial (VE)-cadherin junctions were examined by immunofluorescence. Permeability was determined by the passage of fluorescent dextran through cell monolayers. Signal transduction pathways were analyzed using RhoA, Rho kinase, and stress-activated protein kinase-p38 (SAPK2/p38) inhibitors by guanosine triphosphate-RhoA activation assay and transfection with RhoAT19N. The levels of junction protein expression and phosphorylation of myosin light chain and SAPK2/p38 were assessed by Western blotting. The radiation effects on cell death were verified by clonogenic assays. Results: Radiation induced rapid and persistent actin stress fiber formation and redistribution of VE-cadherin junctions in microvascular, but not umbilical vein endothelial cells, and microtubules and intermediate filaments remained unaffected. Radiation also caused a rapid and persistent increase in microvascular permeability. RhoA-guanosine triphosphatase and Rho kinase were activated by radiation and caused phosphorylation of downstream myosin light chain and the observed cytoskeletal and permeability changes. SAPK2/p38 was activated by radiation but did not influence either the cytoskeleton or permeability. Conclusion: This study is the first to show rapid activation of the RhoA/Rho kinase by radiation in endothelial cells and has demonstrated a link between this pathway and cytoskeletal remodeling and permeability. The results also suggest that the RhoA pathway might be a useful target for modulating the permeability and other effects of radiation for therapeutic gain

  1. Imaging cytoskeleton--mitochondrial membrane attachments by embedment-free electron microscopy of saponin-extracted cells.

    OpenAIRE

    Lin, A; Krockmalnic, G; Penman, S

    1990-01-01

    Embedment-free electron microscopy images the cytoskeleton and nuclear matrix, which are very difficult to visualize in conventional electron micrographs. However, to be effective, cell structures must be depleted of soluble proteins, which otherwise shroud cell architecture. Nonionic detergents effect this extraction, releasing soluble proteins but also destroying all membranes. Saponin can permeabilize plasma membranes, releasing soluble proteins while preserving many cytoplasmic membranes....

  2. Actin cytoskeleton regulation of epithelial mesenchymal transition in metastatic cancer cells.

    Directory of Open Access Journals (Sweden)

    Jay Shankar

    Full Text Available Epithelial-mesenchymal transition (EMT is associated with loss of the cell-cell adhesion molecule E-cadherin and disruption of cell-cell junctions as well as with acquisition of migratory properties including reorganization of the actin cytoskeleton and activation of the RhoA GTPase. Here we show that depolymerization of the actin cytoskeleton of various metastatic cancer cell lines with Cytochalasin D (Cyt D reduces cell size and F-actin levels and induces E-cadherin expression at both the protein and mRNA level. Induction of E-cadherin was dose dependent and paralleled loss of the mesenchymal markers N-cadherin and vimentin. E-cadherin levels increased 2 hours after addition of Cyt D in cells showing an E-cadherin mRNA response but only after 10-12 hours in HT-1080 fibrosarcoma and MDA-MB-231 cells in which E-cadherin mRNA level were only minimally affected by Cyt D. Cyt D treatment induced the nuclear-cytoplasmic translocation of EMT-associated SNAI 1 and SMAD1/2/3 transcription factors. In non-metastatic MCF-7 breast cancer cells, that express E-cadherin and represent a cancer cell model for EMT, actin depolymerization with Cyt D induced elevated E-cadherin while actin stabilization with Jasplakinolide reduced E-cadherin levels. Elevated E-cadherin levels due to Cyt D were associated with reduced activation of Rho A. Expression of dominant-negative Rho A mutant increased and dominant-active Rho A mutant decreased E-cadherin levels and also prevented Cyt D induction of E-cadherin. Reduced Rho A activation downstream of actin remodelling therefore induces E-cadherin and reverses EMT in cancer cells. Cyt D treatment inhibited migration and, at higher concentrations, induced cytotoxicity of both HT-1080 fibrosarcoma cells and normal Hs27 fibroblasts, but only induced mesenchymal-epithelial transition in HT-1080 cancer cells. Our studies suggest that actin remodelling is an upstream regulator of EMT in metastatic cancer cells.

  3. Detachment of glycolytic enzymes from cytoskeleton of Lewis lung carcinoma and colon adenocarcinoma cells induced by clotrimazole and its correlation to cell viability and morphology.

    Science.gov (United States)

    Penso, Julia; Beitner, Rivka

    2002-07-01

    Cancer cells are characterized by a high rate of glycolysis, which is their primary energy source. Glycolysis is known to be controlled by allosteric regulators, as well as by reversible binding of glycolytic enzymes to cytoskeleton. We report here that clotrimazole (l-(alpha-2-chlorotrityl)imidazole), the antifungal azole derivative, which was recently recognized as calmodulin antagonist, induced a dose-dependent detachment of the glycolytic enzymes, phosphofructokinase (ATP: D-fructose-6-phosphate 1-phosphotransferase, EC 2.7.1.11) and aldolase (D-fructose-l,6-bisphosphate D-glyceraldehyde-3-phosphate-lyase, EC 4.1.2.13), from cytoskeleton of LL/2 Lewis lung carcinoma cells and CT-26 colon adenocarcinoma cells. The detachment of glycolytic enzymes from cytoskeleton would reduce the provision of local ATP, in the vicinity of the cytoskeleton membrane, and would also affect cytoskeleton structure and cell shape. We show here that clotrimazole decreased the viability of LL/2 Lewis lung carcinoma cells and CT-26 colon adenocarcinoma cells. After 3h of incubation with clotrimazole, complete cell destruction was detected. Ultrastructural cell damage was manifested by disintegration of the outer membrane by scanning electron microscopy (SEM). The detachment of glycolytic enzymes from cytoskeleton, induced by clotrimazole, preceded the decrease in cell viability, which indicates that this is an early effect and not a result of cell death. Since the cytoskeleton is being recognized as an important modulator of cell function, proliferation, differentiation, and neoplasia, detachment of the glycolytic enzymes from cytoskeleton induced by clotrimazole, as well as its reported inhibitory action on cell proliferation, makes this drug the most promising agent in the treatment of cancer. PMID:12126931

  4. Transcriptomic effects of di-(2-ethylhexyl-phthalate in Syrian hamster embryo cells: an important role of early cytoskeleton disturbances in carcinogenesis?

    Directory of Open Access Journals (Sweden)

    Atienzar Franck

    2011-10-01

    Full Text Available Abstract Background Di-(2-ethylhexyl-phthalate (DEHP is a commonly used plasticizer in polyvinylchloride (PVC formulations and a potentially non-genotoxic carcinogen. The aim of this study was to identify genes whose level of expression is altered by DEHP by using a global wide-genome approach in Syrian hamster embryo (SHE cells, a model similar to human cells regarding their responses to this type of carcinogen. With mRNA Differential Display (DD, we analysed the transcriptional regulation of SHE cells exposed to 0, 12.5, 25 and 50 μM of DEHP for 24 hrs, conditions which induced neoplastic transformation of these cells. A real-time quantitative polymerase chain reaction (qPCR was used to confirm differential expression of genes identified by DD. Results Gene expression profiling showed 178 differentially-expressed fragments corresponding to 122 genes after tblastx comparisons, 79 up-regulated and 43 down-regulated. The genes of interest were involved in many biological pathways, including signal transduction, regulation of the cytoskeleton, xenobiotic metabolism, apoptosis, lipidogenesis, protein conformation, transport and cell cycle. We then focused particularly on genes involved in the regulation of the cytoskeleton, one of the processes occurring during carcinogenesis and in the early steps of neoplastic transformation. Twenty one cytoskeleton-related genes were studied by qPCR. The down-regulated genes were involved in focal adhesion or cell junction. The up-regulated genes were involved in the regulation of the actin cytoskeleton and this would suggest a role of cellular plasticity in the mechanism of chemical carcinogenesis. The gene expression changes identified in the present study were PPAR-independent. Conclusion This study identified a set of genes whose expression is altered by DEHP exposure in mammalian embryo cells. This is the first study that elucidates the genomic changes of DEHP involved in the organization of the

  5. The exocyst at the interface between cytoskeleton and membranes in eukaryotic cells

    Czech Academy of Sciences Publication Activity Database

    Synek, Lukáš; Sekereš, Juraj; Žárský, Viktor

    2014-01-01

    Roč. 4, JAN 2014 (2014). ISSN 1664-462X R&D Projects: GA ČR GPP501/11/P853 Institutional support: RVO:61389030 Keywords : exocyst * actin cytoskeleton * microtubule cytoskeleton Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.948, year: 2014

  6. Proteomic analysis of the action of the Mycobacterium ulcerans toxin mycolactone: targeting host cells cytoskeleton and collagen.

    Directory of Open Access Journals (Sweden)

    José B Gama

    2014-08-01

    Full Text Available Buruli ulcer (BU is a neglected tropical disease caused by Mycobacterium ulcerans. The tissue damage characteristic of BU lesions is known to be driven by the secretion of the potent lipidic exotoxin mycolactone. However, the molecular action of mycolactone on host cell biology mediating cytopathogenesis is not fully understood. Here we applied two-dimensional electrophoresis (2-DE to identify the mechanisms of mycolactone's cellular action in the L929 mouse fibroblast proteome. This revealed 20 changed spots corresponding to 18 proteins which were clustered mainly into cytoskeleton-related proteins (Dync1i2, Cfl1, Crmp2, Actg1, Stmn1 and collagen biosynthesis enzymes (Plod1, Plod3, P4ha1. In line with cytoskeleton conformational disarrangements that are observed by immunofluorescence, we found several regulators and constituents of both actin- and tubulin-cytoskeleton affected upon exposure to the toxin, providing a novel molecular basis for the effect of mycolactone. Consistent with these cytoskeleton-related alterations, accumulation of autophagosomes as well as an increased protein ubiquitination were observed in mycolactone-treated cells. In vivo analyses in a BU mouse model revealed mycolactone-dependent structural changes in collagen upon infection with M. ulcerans, associated with the reduction of dermal collagen content, which is in line with our proteomic finding of mycolactone-induced down-regulation of several collagen biosynthesis enzymes. Our results unveil the mechanisms of mycolactone-induced molecular cytopathogenesis on exposed host cells, with the toxin compromising cell structure and homeostasis by inducing cytoskeleton alterations, as well as disrupting tissue structure, by impairing the extracellular matrix biosynthesis.

  7. Proteomic analysis of the action of the Mycobacterium ulcerans toxin mycolactone: targeting host cells cytoskeleton and collagen.

    Science.gov (United States)

    Gama, José B; Ohlmeier, Steffen; Martins, Teresa G; Fraga, Alexandra G; Sampaio-Marques, Belém; Carvalho, Maria A; Proença, Fernanda; Silva, Manuel T; Pedrosa, Jorge; Ludovico, Paula

    2014-08-01

    Buruli ulcer (BU) is a neglected tropical disease caused by Mycobacterium ulcerans. The tissue damage characteristic of BU lesions is known to be driven by the secretion of the potent lipidic exotoxin mycolactone. However, the molecular action of mycolactone on host cell biology mediating cytopathogenesis is not fully understood. Here we applied two-dimensional electrophoresis (2-DE) to identify the mechanisms of mycolactone's cellular action in the L929 mouse fibroblast proteome. This revealed 20 changed spots corresponding to 18 proteins which were clustered mainly into cytoskeleton-related proteins (Dync1i2, Cfl1, Crmp2, Actg1, Stmn1) and collagen biosynthesis enzymes (Plod1, Plod3, P4ha1). In line with cytoskeleton conformational disarrangements that are observed by immunofluorescence, we found several regulators and constituents of both actin- and tubulin-cytoskeleton affected upon exposure to the toxin, providing a novel molecular basis for the effect of mycolactone. Consistent with these cytoskeleton-related alterations, accumulation of autophagosomes as well as an increased protein ubiquitination were observed in mycolactone-treated cells. In vivo analyses in a BU mouse model revealed mycolactone-dependent structural changes in collagen upon infection with M. ulcerans, associated with the reduction of dermal collagen content, which is in line with our proteomic finding of mycolactone-induced down-regulation of several collagen biosynthesis enzymes. Our results unveil the mechanisms of mycolactone-induced molecular cytopathogenesis on exposed host cells, with the toxin compromising cell structure and homeostasis by inducing cytoskeleton alterations, as well as disrupting tissue structure, by impairing the extracellular matrix biosynthesis. PMID:25101965

  8. Role of cytoskeleton in cytokine production from lung alveolar epithelial cells

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Cytokines are involved in both host defense and inflammatory lung injury. Recent work from our laboratory and others has demonstrated that in addition to classical immune cells, lung alveolar epithelial cells (or pneumocytes) can also produce cytokines in response to various stimuli. This new knowledge has advanced our view of the host defense system in the lung. The regulatory mechanisms of cytokine production have been studied in great detail at various cellular and molecular levels, but the mechanisms of intracellular cytokine transport are largely unknown. Our recent studies suggest that the cytoskeleton could play an important role in mediating intracellular cytokine trafficking. This could be an important regulatory step for cytokine production. For example, lipopolyssacharide (LPS) induced tumor necrosis factor-α (TNF-α) from rat pneumocytes, which was further enhanced by a microfilament-disrupting agent. LPS also induced macrophage inflammatory protein-2(MIP-2), a chemokine for neutrophil recruitment and activation, from rat pneumocytes. This effect was enhanced by microtubule-disrupting agents. We speculate that both microfilaments and microtubules are involved in regulating cytokine transportation in pneumocytes through different mechanisms. Further investigation in on going in my laboratory. From a clinical perspective, if we understand the mechanisms regulating cytokine production and release from lung alveolar epithelial cells, we may be able to enhance or inhibit release of crucial cytokines depending on the clinical situation.

  9. Complexity of the tensegrity structure for dynamic energy and force distribution of cytoskeleton during cell spreading.

    Science.gov (United States)

    Chen, Ting-Jung; Wu, Chia-Ching; Tang, Ming-Jer; Huang, Jong-Shin; Su, Fong-Chin

    2010-01-01

    Cytoskeleton plays important roles in intracellular force equilibrium and extracellular force transmission from/to attaching substrate through focal adhesions (FAs). Numerical simulations of intracellular force distribution to describe dynamic cell behaviors are still limited. The tensegrity structure comprises tension-supporting cables and compression-supporting struts that represent the actin filament and microtubule respectively, and has many features consistent with living cells. To simulate the dynamics of intracellular force distribution and total stored energy during cell spreading, the present study employed different complexities of the tensegrity structures by using octahedron tensegrity (OT) and cuboctahedron tensegrity (COT). The spreading was simulated by assigning specific connection nodes for radial displacement and attachment to substrate to form FAs. The traction force on each FA was estimated by summarizing the force carried in sounding cytoskeletal elements. The OT structure consisted of 24 cables and 6 struts and had limitations soon after the beginning of spreading by declining energy stored in struts indicating the abolishment of compression in microtubules. The COT structure, double the amount of cables and struts than the OT structure, provided sufficient spreading area and expressed similar features with documented cell behaviors. The traction force pointed inward on peripheral FAs in the spread out COT structure. The complex structure in COT provided further investigation of various FA number during different spreading stages. Before the middle phase of spreading (half of maximum spreading area), cell attachment with 8 FAs obtained minimized cytoskeletal energy. The maximum number of 12 FAs in the COT structure was required to achieve further spreading. The stored energy in actin filaments increased as cells spread out, while the energy stored in microtubules increased at initial spreading, peaked in middle phase, and then declined as

  10. Complexity of the tensegrity structure for dynamic energy and force distribution of cytoskeleton during cell spreading.

    Directory of Open Access Journals (Sweden)

    Ting-Jung Chen

    Full Text Available Cytoskeleton plays important roles in intracellular force equilibrium and extracellular force transmission from/to attaching substrate through focal adhesions (FAs. Numerical simulations of intracellular force distribution to describe dynamic cell behaviors are still limited. The tensegrity structure comprises tension-supporting cables and compression-supporting struts that represent the actin filament and microtubule respectively, and has many features consistent with living cells. To simulate the dynamics of intracellular force distribution and total stored energy during cell spreading, the present study employed different complexities of the tensegrity structures by using octahedron tensegrity (OT and cuboctahedron tensegrity (COT. The spreading was simulated by assigning specific connection nodes for radial displacement and attachment to substrate to form FAs. The traction force on each FA was estimated by summarizing the force carried in sounding cytoskeletal elements. The OT structure consisted of 24 cables and 6 struts and had limitations soon after the beginning of spreading by declining energy stored in struts indicating the abolishment of compression in microtubules. The COT structure, double the amount of cables and struts than the OT structure, provided sufficient spreading area and expressed similar features with documented cell behaviors. The traction force pointed inward on peripheral FAs in the spread out COT structure. The complex structure in COT provided further investigation of various FA number during different spreading stages. Before the middle phase of spreading (half of maximum spreading area, cell attachment with 8 FAs obtained minimized cytoskeletal energy. The maximum number of 12 FAs in the COT structure was required to achieve further spreading. The stored energy in actin filaments increased as cells spread out, while the energy stored in microtubules increased at initial spreading, peaked in middle phase, and then

  11. Regulation of the actin cytoskeleton in Helicobacter pylori-induced migration and invasive growth of gastric epithelial cells

    Directory of Open Access Journals (Sweden)

    Rieder Gabriele

    2011-11-01

    Full Text Available Abstract Dynamic rearrangement of the actin cytoskeleton is a significant hallmark of Helicobacter pylori (H. pylori infected gastric epithelial cells leading to cell migration and invasive growth. Considering the cellular mechanisms, the type IV secretion system (T4SS and the effector protein cytotoxin-associated gene A (CagA of H. pylori are well-studied initiators of distinct signal transduction pathways in host cells targeting kinases, adaptor proteins, GTPases, actin binding and other proteins involved in the regulation of the actin lattice. In this review, we summarize recent findings of how H. pylori functionally interacts with the complex signaling network that controls the actin cytoskeleton of motile and invasive gastric epithelial cells.

  12. Computational model for the cell-mechanical response of the osteocyte cytoskeleton based on self-stabilizing tensegrity structures.

    Science.gov (United States)

    Kardas, Dieter; Nackenhorst, Udo; Balzani, Daniel

    2013-01-01

    The mechanism by which mechanical stimulation on osteocytes results in biochemical signals that initiate the remodeling process inside living bone tissue is largely unknown. Even the type of stimulation acting on these cells is not yet clearly identified. However, the cytoskeleton of osteocytes is suggested to play a major role in the mechanosensory process due to the direct connection to the nucleus. In this paper, a computational approach to model and simulate the cell structure of osteocytes based on self-stabilizing tensegrity structures is suggested. The computational model of the cell consists of the major components with respect to mechanical aspects: the integrins that connect the cell with the extracellular bone matrix, and different types of protein fibers (microtubules and intermediate filaments) that form the cytoskeleton, the membrane-cytoskeleton (microfilaments), the nucleus and the centrosome. The proposed geometrical cell models represent the cell in its physiological environment which is necessary in order to give a statement on the cell behavior in vivo. Studies on the mechanical response of osteocytes after physiological loading and in particular the mechanical response of the nucleus show that the load acting on the nucleus is rising with increasing deformation applied to the integrins. PMID:22527364

  13. Regulation of retinoschisin secretion in Weri-Rb1 cells by the F-actin and microtubule cytoskeleton.

    Directory of Open Access Journals (Sweden)

    Eiko Kitamura

    Full Text Available Retinoschisin is encoded by the gene responsible for X-linked retinoschisis (XLRS, an early onset macular degeneration that results in a splitting of the inner layers of the retina and severe loss in vision. Retinoschisin is predominantly expressed and secreted from photoreceptor cells as a homo-oligomer protein; it then associates with the surface of retinal cells and maintains the retina cellular architecture. Many missense mutations in the XLRS1 gene are known to cause intracellular retention of retinoschisin, indicating that the secretion process of the protein is a critical step for its normal function in the retina. However, the molecular mechanisms underlying retinoschisin's secretion remain to be fully elucidated. In this study, we investigated the role of the F-actin cytoskeleton in the secretion of retinoschisin by treating Weri-Rb1 cells, which are known to secrete retinoschisin, with cytochalasin D, jasplakinolide, Y-27632, and dibutyryl cGMP. Our results show that cytochalasin D and jasplakinolide inhibit retinoschisin secretion, whereas Y-27632 and dibutyryl cGMP enhance secretion causing F-actin alterations. We also demonstrate that high concentrations of taxol, which hyperpolymerizes microtubules, inhibit retinoschisin secretion. Our data suggest that retinoschisin secretion is regulated by the F-actin cytoskeleton, that cGMP or inhibition of ROCK alters F-actin structure enhancing the secretion, and that the microtubule cytoskeleton is also involved in this process.

  14. A role for the cytoskeleton in STAT5 activation in MCF7 human breast cancer cells stimulated with EGF.

    Science.gov (United States)

    Lopez-Perez, Mario; Salazar, Eduardo Perez

    2006-01-01

    A rapid increase in the tyrosine phosphorylation of signal transducers and activators of transcription (STAT) proteins has been extensively documented in cells stimulated with cytokines and growth factors. However, the mechanisms by which these transcription factors translocate to the nucleus have not been studied in detail. Our results demonstrate that stimulation of MCF7 cells with epidermal growth factor (EGF) promoted an increase in the phosphorylation of STAT5 at Tyr-694, as revealed by site-specific antibodies that recognized the phosphorylated state of this residue. In addition, EGF stimulated STAT5 nuclear translocation and an increased in STAT5 DNA binding activity. Prevention of microtubules and microfilaments polymerization induced a partial inhibition of STAT5 nuclear translocation and STAT5 DNA binding activity. However, STAT5 phosphorylation at Tyr-694 was dependent on the integrity of microtubule network and it was independent of the integrity of actin cytoskeleton. Furthermore, EGF induced the formation of the associations STAT5-tubulin and STAT5-kinesin heavy chain in a fashion dependent of cytoskeleton integrity. In summary, our results demonstrate, for the first time, that cytoskeleton plays an important role in STAT5 activation and translocation into the nucleus in MCF7 cells stimulated with EGF. PMID:16765629

  15. Quantitative analyses of the plant cytoskeleton reveal underlying organizational principles

    CERN Document Server

    Breuer, David; Sampathkumar, Arun; Hollandt, Florian; Persson, Staffan; Nikoloski, Zoran

    2015-01-01

    The actin and microtubule cytoskeletons are vital structures for cell growth and development across all species. While individual molecular mechanisms underpinning actin and microtubule dynamics have been intensively studied, principles that govern the cytoskeleton organization remain largely unexplored. Here, we captured biologically relevant characteristics of the plant cytoskeleton through a network-driven imaging-based approach allowing to quantitatively assess dynamic features of the cytoskeleton. By introducing suitable null models, we demonstrate that the plant cytoskeletal networks exhibit properties required for efficient transport, namely, short average path lengths and high robustness. We further show that these advantageous features are maintained during temporal cytoskeletal re-arrangements. Interestingly, man-made transportation networks exhibit similar properties, suggesting general laws of network organization supporting diverse transport processes. The proposed network-driven analysis can be ...

  16. Complete disintegration of the microtubular cytoskeleton precedes its auxin-mediated reconstruction in postmitotic maize root cells

    Science.gov (United States)

    Baluska, F.; Barlow, P. W.; Volkmann, D.

    1996-01-01

    The inhibitory action of 0.1 microM auxin (IAA) on maize root growth was closely associated with a rapid and complete disintegration of the microtubular (MT) cytoskeleton, as visualized by indirect immunofluorescence of tubulin, throughout the growth region. After 30 min of this treatment, only fluorescent spots were present in root cells, accumulating either around nuclei or along cell walls. Six h later, in addition to some background fluorescence, dense but partially oriented oblique or longitudinal arrays of cortical MTs (CMTs) were found in most growing cells of the root apex. After 24 h of treatment, maize roots had adapted to the auxin, as inferred from the slowly recovering elongation rate and from the reassembly of a dense and well-ordered MT cytoskeleton which showed only slight deviations from that of the control root cells. Taxol pretreatment (100 microM, 24 h) prevented not only the rapid auxin-mediated disintegration of the MT cytoskeleton but also a reorientation of the CMT arrays, from transversal to longitudinal. The only tissue to show MTs in their cells throughout the auxin treatment was the epidermis. Significant resistance of transverse CMT arrays in these cells towards auxin was confirmed using a higher auxin concentration (100 microM, 24 h). The latter auxin dose also revealed inter-tissue-specific responses to auxin: outer cortical cell files reoriented their CMTs from the transversal to longitudinal orientation, whereas inner cortical cell files lost their MTs. This high auxin-mediated response, associated with the swelling of root apices, was abolished with the pretreatment of maize root with taxol.

  17. Actin-associated protein palladin promotes tumor cell invasion by linking extracellular matrix degradation to cell cytoskeleton

    Science.gov (United States)

    von Nandelstadh, Pernilla; Gucciardo, Erika; Lohi, Jouko; Li, Rui; Sugiyama, Nami; Carpen, Olli; Lehti, Kaisa

    2014-01-01

    Basal-like breast carcinomas, characterized by unfavorable prognosis and frequent metastases, are associated with epithelial-to-mesenchymal transition. During this process, cancer cells undergo cytoskeletal reorganization and up-regulate membrane-type 1 matrix metalloproteinase (MT1-MMP; MMP14), which functions in actin-based pseudopods to drive invasion by extracellular matrix degradation. However, the mechanisms that couple matrix proteolysis to the actin cytoskeleton in cell invasion have remained unclear. On the basis of a yeast two-hybrid screen for the MT1-MMP cytoplasmic tail-binding proteins, we identify here a novel Src-regulated protein interaction between the dynamic cytoskeletal scaffold protein palladin and MT1-MMP. These proteins were coexpressed in invasive human basal-like breast carcinomas and corresponding cell lines, where they were associated in the same matrix contacting and degrading membrane complexes. The silencing and overexpression of the 90-kDa palladin isoform revealed the functional importance of the interaction with MT1-MMP in pericellular matrix degradation and mesenchymal tumor cell invasion, whereas in MT1-MMP–negative cells, palladin overexpression was insufficient for invasion. Moreover, this invasion was inhibited in a dominant-negative manner by an immunoglobulin domain–containing palladin fragment lacking the dynamic scaffold and Src-binding domains. These results identify a novel protein interaction that links matrix degradation to cytoskeletal dynamics and migration signaling in mesenchymal cell invasion. PMID:24989798

  18. Extra-nuclear signaling of progesterone receptor to breast cancer cell movement and invasion through the actin cytoskeleton.

    Directory of Open Access Journals (Sweden)

    Xiao-Dong Fu

    Full Text Available Progesterone plays a role in breast cancer development and progression but the effects on breast cancer cell movement or invasion have not been fully explored. In this study, we investigate the actions of natural progesterone and of the synthetic progestin medroxyprogesterone acetate (MPA on actin cytoskeleton remodeling and on breast cancer cell movement and invasion. In particular, we characterize the nongenomic signaling cascades implicated in these actions. T47-D breast cancer cells display enhanced horizontal migration and invasion of three-dimensional matrices in the presence of both progestins. Exposure to the hormones triggers a rapid remodeling of the actin cytoskeleton and the formation of membrane ruffles required for cell movement, which are dependent on the rapid phosphorylation of the actin-regulatory protein moesin. The extra-cellular small GTPase RhoA/Rho-associated kinase (ROCK-2 cascade plays central role in progesterone- and MPA-induced moesin activation, cell migration and invasion. In the presence of progesterone, progesterone receptor A (PRA interacts with the G protein G alpha(13, while MPA drives PR to interact with tyrosine kinase c-Src and to activate phosphatidylinositol-3 kinase, leading to the activation of RhoA/ROCK-2. In conclusion, our findings manifest that progesterone and MPA promote breast cancer cell movement via rapid actin cytoskeleton remodeling, which are mediated by moesin activation. These events are triggered by RhoA/ROCK-2 cascade through partially differing pathways by the two compounds. These results provide original mechanistic explanations for the effects of progestins on breast cancer progression and highlight potential targets to treat endocrine-sensitive breast cancers.

  19. The role of the cytoskeleton in sensing changes in gravity by nonspecialized cells

    NARCIS (Netherlands)

    Vorselen, Daan; Roos, Wouter H.; MacKintosh, Fred C.; Wuite, Gijs J. L.; van Loon, Jack J. W. A.

    2014-01-01

    A large body of evidence indicates that single cells in vitro respond to changes in gravity, and that this response might play an important role for physiological changes at the organism level during spaceflight. Gravity can lead to changes in cell proliferation, differentiation, signaling, and gene

  20. Differential gene regulation under altered gravity conditions in follicular thyroid cancer cells: relationship between the extracellular matrix and the cytoskeleton.

    Science.gov (United States)

    Ulbrich, Claudia; Pietsch, Jessica; Grosse, Jirka; Wehland, Markus; Schulz, Herbert; Saar, Katrin; Hübner, Norbert; Hauslage, Jens; Hemmersbach, Ruth; Braun, Markus; van Loon, Jack; Vagt, Nicole; Egli, Marcel; Richter, Peter; Einspanier, Ralf; Sharbati, Soroush; Baltz, Theo; Infanger, Manfred; Ma, Xiao; Grimm, Daniela

    2011-01-01

    Extracellular matrix proteins, adhesion molecules, and cytoskeletal proteins form a dynamic network interacting with signalling molecules as an adaptive response to altered gravity. An important issue is the exact differentiation between real microgravity responses of the cells or cellular reactions to hypergravity and/or vibrations. To determine the effects of real microgravity on human cells, we used four DLR parabolic flight campaigns and focused on the effects of short-term microgravity (22 s), hypergravity (1.8 g), and vibrations on ML-1 thyroid cancer cells. No signs of apoptosis or necrosis were detectable. Gene array analysis revealed 2,430 significantly changed transcripts. After 22 s microgravity, the F-actin and cytokeratin cytoskeleton was altered, and ACTB and KRT80 mRNAs were significantly upregulated after the first and thirty-first parabolas. The COL4A5 mRNA was downregulated under microgravity, whereas OPN and FN were significantly upregulated. Hypergravity and vibrations did not change ACTB, KRT-80 or COL4A5 mRNA. MTSS1 and LIMA1 mRNAs were downregulated/slightly upregulated under microgravity, upregulated in hypergravity and unchanged by vibrations. These data indicate that the graviresponse of ML-1 cells occurred very early, within the first few seconds. Downregulated MTSS1 and upregulated LIMA1 may be an adaptive mechanism of human cells for stabilizing the cytoskeleton under microgravity conditions. PMID:21865726

  1. Cytoskeleton-interacting LIM-domain protein CRP1 suppresses cell proliferation and protects from stress-induced cell death

    International Nuclear Information System (INIS)

    Members of the cysteine-rich protein (CRP) family are actin cytoskeleton-interacting LIM-domain proteins known to act in muscle cell differentiation. We have earlier found that CRP1, a founding member of this family, is transcriptionally induced by UV radiation in human diploid fibroblasts [M. Gentile, L. Latonen, M. Laiho, Cell cycle arrest and apoptosis provoked by UV radiation-induced DNA damage are transcriptionally highly divergent responses, Nucleic Acids Res. 31 (2003) 4779-4790]. Here we show that CRP1 is induced by growth-inhibitory signals, such as increased cellular density, and cytotoxic stress induced by UV radiation or staurosporine. We found that high levels of CRP1 correlate with differentiation-associated morphology towards the myofibroblast lineage and that expression of ectopic CRP1 suppresses cell proliferation. Following UV- and staurosporine-induced stresses, expression of CRP1 provides a survival advantage evidenced by decreased cellular death and increased cellular metabolic activity and attachment. Our studies identify that CRP1 is a novel stress response factor, and provide evidence for its growth-inhibitory and cytoprotective functions

  2. The cytoskeleton adaptor protein ankyrin-1 is upregulated by p53 following DNA damage and alters cell migration.

    Science.gov (United States)

    Hall, A E; Lu, W-T; Godfrey, J D; Antonov, A V; Paicu, C; Moxon, S; Dalmay, T; Wilczynska, A; Muller, P A J; Bushell, M

    2016-01-01

    The integrity of the genome is maintained by a host of surveillance and repair mechanisms that are pivotal for cellular function. The tumour suppressor protein p53 is a major component of the DNA damage response pathway and plays a vital role in the maintenance of cell-cycle checkpoints. Here we show that a microRNA, miR-486, and its host gene ankyrin-1 (ANK1) are induced by p53 following DNA damage. Strikingly, the cytoskeleton adaptor protein ankyrin-1 was induced over 80-fold following DNA damage. ANK1 is upregulated in response to a variety of DNA damage agents in a range of cell types. We demonstrate that miR-486-5p is involved in controlling G1/S transition following DNA damage, whereas the induction of the ankyrin-1 protein alters the structure of the actin cytoskeleton and sustains limited cell migration during DNA damage. Importantly, we found that higher ANK1 expression correlates with decreased survival in cancer patients. Thus, these observations highlight ANK1 as an important effector downstream of the p53 pathway. PMID:27054339

  3. Drought stress delays endosperm development and misregulates genes associated with cytoskeleton organization and grain quality proteins in developing wheat seeds.

    Science.gov (United States)

    Begcy, Kevin; Walia, Harkamal

    2015-11-01

    Drought stress is a major yield-limiting factor for wheat. Wheat yields are particularly sensitive to drought stress during reproductive development. Early seed development stage is an important determinant of seed size, one of the yield components. We specifically examined the impact of drought stress imposed during postzygotic early seed development in wheat. We imposed a short-term drought stress on plants with day-old seeds and observed that even a short-duration drought stress significantly reduced the size of developing seeds as well as mature seeds. Drought stress delayed the developmental transition from syncytial to cellularized stage of endosperm. Coincident with reduced seed size and delayed endosperm development, a subset of genes associated with cytoskeleton organization was misregulated in developing seeds under drought-stressed. Several genes linked to hormone pathways were also differentially regulated in response to drought stress in early seeds. Notably, drought stress strongly repressed the expression of wheat storage protein genes such as gliadins, glutenins and avenins as early as 3 days after pollination. Our results provide new insights on how some of the early seed developmental events are impacted by water stress, and the underlying molecular pathways that can possibly impact both grain size and quality in wheat. PMID:26475192

  4. Effect of endocrine disruptors on the cytoskeleton of MCF-7 cells

    Czech Academy of Sciences Publication Activity Database

    Kubátová, Alena; Pěknicová, Jana; Kyselová, Vendula; Buckiová, Daniela; Paleček, J.; Dráber, Pavel

    Česká republika: XXX , 2002. s. X-X. [Symposium českých reprodukčních imunologů s mezinárodní účastí/8./. 06.10.2002-09.10.2002, Žďár nad Sázavou] R&D Projects: GA ČR GA303/00/1651; GA ČR GA204/02/1373; GA MZd NJ5851 Keywords : endocrine disruptors * cytoskeleton Subject RIV: EB - Genetics ; Molecular Biology

  5. EFFECTS OF ESTETROL ON MIGRATION AND INVASION IN T47-D BREAST CANCER CELLS THROUGH THE ACTIN CYTOSKELETON

    Directory of Open Access Journals (Sweden)

    Maria Silvia eGiretti

    2014-05-01

    Full Text Available Estetrol (E4 is a natural human estrogen present at high concentrations during pregnancy. Due to its high oral bioavailability and long plasma half-life, E4 is particularly suitable for therapeutic applications. E4 acts as a selective estrogen receptor modulator, exerting estrogenic actions on the endometrium or the central nervous system, while antagonizing the actions of estradiol in the breast. We tested the effects of E4 on its own or in the presence of 17β-estradiol (E2 on T47-D estrogen receptor (ER positive breast cancer cell migration and invasion of three-dimensional matrices. E4 administration to T47-D cells weakly stimulated migration and invasion. However, E4 decreased the extent of movement and invasion induced by E2. Breast cancer cell movement requires a remodeling of the actin cytoskeleton. During exposure to E4, a weak, concentration-dependent, redistribution of actin fibers towards the cell membrane was observed. However, when E4 was added to E2, a inhibition of actin remodeling induced by E2 was seen. Estrogens stimulate ER+ breast cancer cell movement through the ezrin-radixin-moesin (ERM family of actin regulatory proteins, inducing actin and cell membrane remodeling. E4 was a weak inducer of moesin phosphorylation on Thr558, which accounts for its functional activation. In co-treatment with E2, E4 blocked the activation of this actin controller in a concentration-related fashion. These effects were obtained through recruitment of ERα. In conclusion, E4 acted as a weak estrogen on breast cancer cell cytoskeleton remodeling and movement. However, when E2 was present, E4 counteracted the stimulatory actions of E2. This contributes to the emerging hypothesis that E4 may be a naturally occurring estrogen receptor modulator in the breast.

  6. Effects of Estetrol on Migration and Invasion in T47-D Breast Cancer Cells through the Actin Cytoskeleton.

    Science.gov (United States)

    Giretti, Maria Silvia; Montt Guevara, Maria Magdalena; Cecchi, Elena; Mannella, Paolo; Palla, Giulia; Spina, Stefania; Bernacchi, Guja; Di Bello, Silvia; Genazzani, Andrea Riccardo; Genazzani, Alessandro D; Simoncini, Tommaso

    2014-01-01

    Estetrol (E4) is a natural human estrogen present at high concentrations during pregnancy. Due to its high oral bioavailability and long plasma half-life, E4 is particularly suitable for therapeutic applications. E4 acts as a selective estrogen receptor (ER) modulator, exerting estrogenic actions on the endometrium or the central nervous system, while antagonizing the actions of estradiol in the breast. We tested the effects of E4 on its own or in the presence of 17β-estradiol (E2) on T47-D ER+ breast cancer cell migration and invasion of three-dimensional matrices. E4 administration to T47-D cells weakly stimulated migration and invasion. However, E4 decreased the extent of movement and invasion induced by E2. Breast cancer cell movement requires a remodeling of the actin cytoskeleton. During exposure to E4, a weak, concentration-dependent, re-distribution of actin fibers toward the cell membrane was observed. However, when E4 was added to E2, an inhibition of actin remodeling induced by E2 was seen. Estrogens stimulate ER+ breast cancer cell movement through the ezrin-radixin-moesin family of actin regulatory proteins, inducing actin and cell membrane remodeling. E4 was a weak inducer of moesin phosphorylation on Thr(558), which accounts for its functional activation. In co-treatment with E2, E4 blocked the activation of this actin controller in a concentration-related fashion. These effects were obtained through recruitment of estrogen receptor-α. In conclusion, E4 acted as a weak estrogen on breast cancer cell cytoskeleton remodeling and movement. However, when E2 was present, E4 counteracted the stimulatory actions of E2. This contributes to the emerging hypothesis that E4 may be a naturally occurring ER modulator in the breast. PMID:24904530

  7. Silicon nanocrystals and nanodiamonds in live cells: photoluminescence characteristics, cytotoxicity and interaction with cell cytoskeleton

    Czech Academy of Sciences Publication Activity Database

    Fučíková, A.; Valenta, J.; Pelant, Ivan; Hubálek Kalbáčová, M.; Brož, A.; Rezek, Bohuslav; Kromka, Alexander; Bakaeva, Zulfiya

    2014-01-01

    Roč. 4, č. 20 (2014), s. 10334-10342. ISSN 2046-2069 R&D Projects: GA ČR(CZ) GBP108/12/G108; GA ČR GA202/09/2078 Institutional support: RVO:68378271 ; RVO:61389013 Keywords : silicon nanocrystals * nanodiamonds * live cells * photoluminescence Subject RIV: BO - Biophysics Impact factor: 3.840, year: 2014

  8. Cytoskeleton alterations induced by Geodia corticostylifera depsipeptides in breast cancer cells.

    Science.gov (United States)

    Rangel, Marisa; Prado, Marisa P; Konno, Katsuhiro; Naoki, Hideo; Freitas, José C; Machado-Santelli, Glaucia M

    2006-09-01

    Crude extracts of the marine sponge Geodia corticostylifera from Brazilian Coast have previously shown antibacterial, antifungal, cytotoxic, haemolytic and neurotoxic activities. The present work describes the isolation of the cyclic peptides geodiamolides A, B, H and I (1-4) from G. corticostylifera and their anti-proliferative effects against sea urchin eggs and human breast cancer cell lineages. Its structure-activity relationship is discussed as well. In an initial series of experiments these peptides inhibited the first cleavage of sea urchin eggs (Lytechinus variegatus). Duplication of nuclei without complete egg cell division indicated the mechanism of action might be related to microfilament disruption. Further studies showed that the geodiamolides have anti-proliferative activity against human breast cancer cell lines (T47D and MCF7). Using fluorescence techniques and confocal microscopy, we found evidence that the geodiamolides A, B, H and I act by disorganizing actin filaments of T47D and MCF7 cancer cells, in a way similar to other depsipeptides (such as jaspamide 5 and dolastatins), keeping the normal microtubule organization. Normal cells lines (primary culture human fibroblasts and BRL3A rat liver epithelial cells) were not affected by the treatment as tumor cells were, thus indicating the biomedical potential of these compounds. PMID:16843570

  9. Components and distributions of cytoskeleton network in neoplastic Hep G2cells extracted with triton X-100 and (NH4)2SO4

    Institute of Scientific and Technical Information of China (English)

    Hai Wei Zhang

    2000-01-01

    AIM To explore the components and the distributions of the cytoskeleton network in neoplastic Hep G2 cellsextracted with triton X-100 and (NH4)2SO4.METHODS Using the mouse lung adenocarcinoma cell sublines (C6/C7) with low and high metastasis as acontrol, the human hepatocellular carcinoma cell line (Hep G2) as well as the cell sublines (C6/C7) wasextracted with triton X-100 and/or (NH4)2SO4, then stained with Coomasie blue R250 or labeled withimmunoenzymatic technique to identify the cytokeratin-type or vimentin-type intermediate filamentcomponents and study the distributions of cytoskeleton comparatively.RESULTS Extracted with triton X-100 and/or (NH4)2SO4, then stained with Coomasie blue R250, the cells'cytoskeleton network were showed clearly; still it was very difficult to identify the variations of thecytoskeleton network in morphology by light microscopy when the same cells was extracted with the differentextraction above; compared with the low metastasis cells (C7), most of the high metastasis cells (C6) werelikely showed that the distribution of the cytoskeleton network was more irregular and uneven as well asgathering on one side to the cell neucleus, and so did a few of Hep G2 cells (the percentage of regular andeven distribution of cytoskeleton, C6: 8.0±1.0; C7: 84.0±2.0; Hep G2: 96.0±2.0; n = 500; x2-test,P<0.01). Moreover, extracted with triton X-100 and (NH4)2SO4, then labeled by immunoenzymatictechnique, the mouse lung adenocarcinoma sublines (C6/C7) were positive for cytokeratin antibody only, butthe hepatocellular carcinoma cell (Hep G2) was positive for both cytokeratin and vimentin antibodies.Besides these, in the same cells, the distribution of the intermediate filament network showed by theimmunoenzymatic technique was nearly keeping with that of the cytoskeleton network showed by Coomasieblue R250 stain.CONCLUSION ① It is very difficult to identify the variations of the cytoskeleton network in morphologyby light microscopy when the same

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

    Directory of Open Access Journals (Sweden)

    H. Q. Zhang

    2014-02-01

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

  11. Calponin isoforms CNN1, CNN2 and CNN3: Regulators for actin cytoskeleton functions in smooth muscle and non-muscle cells.

    Science.gov (United States)

    Liu, Rong; Jin, J-P

    2016-07-01

    Calponin is an actin filament-associated regulatory protein expressed in smooth muscle and many types of non-muscle cells. Three homologous genes, CNN1, CNN2 and CNN3, encoding calponin isoforms 1, 2, and 3, respectively, are present in vertebrate species. All three calponin isoforms are actin-binding proteins with functions in inhibiting actin-activated myosin ATPase and stabilizing the actin cytoskeleton, while each isoform executes different physiological roles based on their cell type-specific expressions. Calponin 1 is specifically expressed in smooth muscle cells and plays a role in fine-tuning smooth muscle contractility. Calponin 2 is expressed in both smooth muscle and non-muscle cells and regulates multiple actin cytoskeleton-based functions. Calponin 3 participates in actin cytoskeleton-based activities in embryonic development and myogenesis. Phosphorylation has been extensively studied for the regulation of calponin functions. Cytoskeleton tension regulates the transcription of CNN2 gene and the degradation of calponin 2 protein. This review summarizes our knowledge learned from studies over the past three decades, focusing on the evolutionary lineage of calponin isoform genes, their tissue- and cell type-specific expressions, structure-function relationships, and mechanoregulation. PMID:26970176

  12. Immunofluorescence detection of the cytoskeleton and extracellular matrix in tissue and cultured cells.

    Science.gov (United States)

    Smith-Clerc, Josiane; Hinz, Boris

    2010-01-01

    "A picture is worth a thousand words" goes the proverb. A poor picture however can be worse than saying nothing at all. This is particularly true for immunofluorescence pictures that in addition to their informative character bear an esthetic component. We here provide a panel of straightforward methods to process tissue sections and cultured cells for immunostaining of cytoskeletal elements, primarily those associated with actin filaments. We want to emphasize to the reader the fact that the choice of the processing method will have an important influence on the outcome of the immunostaining and thus on the interpretation of the results. Fixation of cultured cells with cross-linking reagents such as paraformaldehyde efficiently preserves structural elements at the expense of reduced antigenicity. The degree and timing of cell permeabilization with detergents, along with chemical cross-linking, contributes to the clarity and resolution of distinct structures but can also lead to loss of information. Fixation with organic solvents like methanol will, in most cases, better preserve antigens but will produce a higher background and impact on structural integrity. Therefore, it is recommended to test different protocols for a "new" protein or epitope - the results will pay back your investment. PMID:19960321

  13. Unveiling interactions among mitochondria, caspase-like proteases, and the actin cytoskeleton during plant programmed cell death (PCD.

    Directory of Open Access Journals (Sweden)

    Christina E N Lord

    Full Text Available Aponogeton madagascariensis produces perforations over its leaf surface via programmed cell death (PCD. PCD begins between longitudinal and transverse veins at the center of spaces regarded as areoles, and continues outward, stopping several cells from these veins. The gradient of PCD that exists within a single areole of leaves in an early stage of development was used as a model to investigate cellular dynamics during PCD. Mitochondria have interactions with a family of proteases known as caspases, and the actin cytoskeleton during metazoan PCD; less is known regarding these interactions during plant PCD. This study employed the actin stain Alexa Fluor 488 phalloidin, the actin depolymerizer Latrunculin B (Lat B, a synthetic caspase peptide substrate and corresponding specific inhibitors, as well as the mitochondrial pore inhibitor cyclosporine A (CsA to analyze the role of these cellular constituents during PCD. Results depicted that YVADase (caspase-1 activity is higher during the very early stages of perforation formation, followed by the bundling and subsequent breakdown of actin. Actin depolymerization using Lat B caused no change in YVADase activity. In vivo inhibition of YVADase activity prevented PCD and actin breakdown, therefore substantiating actin as a likely substrate for caspase-like proteases (CLPs. The mitochondrial pore inhibitor CsA significantly decreased YVADase activity, and prevented both PCD and actin breakdown; therefore suggesting the mitochondria as a possible trigger for CLPs during PCD in the lace plant. To our knowledge, this is the first in vivo study using either caspase-1 inhibitor (Ac-YVAD-CMK or CsA, following which the actin cytoskeleton was examined. Overall, our findings suggest the mitochondria as a possible upstream activator of YVADase activity and implicate these proteases as potential initiators of actin breakdown during perforation formation via PCD in the lace plant.

  14. The Drosophila IKK-related kinase (Ik2 and Spindle-F proteins are part of a complex that regulates cytoskeleton organization during oogenesis

    Directory of Open Access Journals (Sweden)

    Shaanan Boaz

    2008-09-01

    Full Text Available Abstract Background IkappaB kinases (IKKs regulate the activity of Rel/NF-kappaB transcription factors by targeting their inhibitory partner proteins, IkappaBs, for degradation. The Drosophila genome encodes two members of the IKK family. Whereas the first is a kinase essential for activation of the NF-kappaB pathway, the latter does not act as IkappaB kinase. Instead, recent findings indicate that Ik2 regulates F-actin assembly by mediating the function of nonapoptotic caspases via degradation of DIAP1. Also, it has been suggested that ik2 regulates interactions between the minus ends of the microtubules and the actin-rich cortex in the oocyte. Since spn-F mutants display oocyte defects similar to those of ik2 mutant, we decided to investigate whether Spn-F could be a direct regulatory target of Ik2. Results We found that Ik2 binds physically to Spn-F, biomolecular interaction analysis of Spn-F and Ik2 demonstrating that both proteins bind directly and form a complex. We showed that Ik2 phosphorylates Spn-F and demonstrated that this phosphorylation does not lead to Spn-F degradation. Ik2 is localized to the anterior ring of the oocyte and to punctate structures in the nurse cells together with Spn-F protein, and both proteins are mutually required for their localization. Conclusion We conclude that Ik2 and Spn-F form a complex, which regulates cytoskeleton organization during Drosophila oogenesis and in which Spn-F is the direct regulatory target for Ik2. Interestingly, Ik2 in this complex does not function as a typical IKK in that it does not direct SpnF for degradation following phosphorylation.

  15. A Dual Role for Melatonin in Medaka Ovulation: Ensuring Prostaglandin Synthesis and Actin Cytoskeleton Rearrangement in Follicular Cells.

    Science.gov (United States)

    Ogiwara, Katsueki; Takahashi, Takayuki

    2016-03-01

    Understanding the direct effects of melatonin on vertebrate ovulation remains a challenge. The present study provides the first characterization of the role of melatonin in ovulation using the teleost medaka. The melatonin receptor antagonist luzindole inhibited in vitro follicle ovulation. In the preovulatory follicles, arylalkylamineN-acetyltransferase 1a and hydroxyindole-O-methyltransferase 2, the enzymes responsible for melatonin synthesis, were expressed in the granulosa cells throughout the 24 h spawning cycle. The granulosa cells of the follicle also expressed the melatonin receptor 1a-a. An in vitro characterization study using medaka OLHNI-2 cells revealed that melatonin and luzindole act as an agonist and an antagonist, respectively, of the melatonin receptor. The intracellular cAMP levels in these cells were reduced after melatonin treatment. The expression of cytosolic phospholipase A2 group 4a (Pla2g4a), the enzyme producing arachidonic acid (cyclooxygenase-2 substrate), was inhibited in the granulosa cells in luzindole-treated follicles. Follicular prostaglandin E2levels and in vitro follicle ovulation were suppressed in follicles isolated at 12 h prior to ovulation and incubated with the Pla2g4a inhibitor AACOCF3. The G-actin:F-actin ratios in follicular cells increased with approaching ovulation, but this increase was suppressed after luzindole treatment. The phosphorylation of moesin, an ezrin-radixin-moesin protein, was inhibited in the follicular cells in luzindole-treated follicles. These results indicate a dual role for melatonin in medaka ovulation: melatonin ensures prostaglandin E2synthesis throughout the spawning cycle and induces actin cytoskeleton rearrangement in the follicular cells at ovulation. PMID:26864196

  16. Chaperonin filaments: The archael cytoskeleton

    Energy Technology Data Exchange (ETDEWEB)

    Trent, J.D.; Kagawa, H.K.; Yaoi, Takuro; Olle, E.; Zaluzec, N.J.

    1997-08-01

    Chaperonins are multi-subunit double-ring complexed composed of 60-kDa proteins that are believed to mediate protein folding in vivo. The chaperonins in the hyperthermophilic archaeon Sulfolobus shibatae are composed of the organism`s two most abundant proteins, which represent 4% of its total protein and have an intracellular concentration of {ge} 3.0 mg/ml. At concentrations of 1.0 mg/ml, purified chaperonin proteins aggregate to form ordered filaments. Filament formation, which requires Mg{sup ++} and nucleotide binding (not hydrolysis), occurs at physiological temperatures under conditions suggesting filaments may exist in vivo. If the estimated 4,600 chaperonins per cell, formed filaments in vivo, they could create a matrix of filaments that would span the diameter of an average S. shibatae cell 100 times. Direct observations of unfixed, minimally treated cells by intermediate voltage electron microscopy (300 kV) revealed an intracellular network of filaments that resembles chaperonin filaments produced in vitro. The hypothesis that the intracellular network contains chaperonins is supported by immunogold analyses. The authors propose that chaperonin activity may be regulated in vivo by filament formation and that chaperonin filaments may serve a cytoskeleton-like function in archaea and perhaps in other prokaryotes.

  17. Effects of Endogenous Signals and Fusarium oxysporum on the Mechanism Regulating Genistein Synthesis and Accumulation in Yellow Lupine and Their Impact on Plant Cell Cytoskeleton

    Directory of Open Access Journals (Sweden)

    Magda Formela

    2014-08-01

    Full Text Available The aim of the study was to examine cross-talk interactions of soluble sugars (sucrose, glucose and fructose and infection caused by Fusarium oxysporum f.sp. lupini on the synthesis of genistein in embryo axes of Lupinus luteus L.cv. Juno. Genistein is a free aglycone, highly reactive and with the potential to inhibit fungal infection and development of plant diseases. As signal molecules, sugars strongly stimulated accumulation of isoflavones, including genistein, and the expression of the isoflavonoid biosynthetic genes. Infection significantly enhanced the synthesis of genistein and other isoflavone aglycones in cells of embryo axes of yellow lupine with high endogenous sugar levels. The activity of β-glucosidase, the enzyme that releases free aglycones from their glucoside bindings, was higher in the infected tissues than in the control ones. At the same time, a very strong generation of the superoxide anion radical was observed in tissues with high sugar contents already in the initial stage of infection. During later stages after inoculation, a strong generation of semiquinone radicals was observed, which level was relatively higher in tissues deficient in sugars than in those with high sugar levels. Observations of actin and tubulin cytoskeletons in cells of infected embryo axes cultured on the medium with sucrose, as well as the medium without sugar, showed significant differences in their organization.

  18. Patterning and lifetime of plasma membrane-localized cellulose synthase is dependent on actin organization in Arabidopsis interphase cells

    NARCIS (Netherlands)

    Sampathkumar, A.; Gutierrez, R.; McFarlane, H.E.; Bringmann, M.; Lindeboom, J.J.; Emons, A.M.C.; Samuels, L.; Ketelaar, T.; Ehrhardt, D.W.; Persson, S.

    2013-01-01

    The actin and microtubule cytoskeletons regulate cell shape across phyla, from bacteria to metazoans. In organisms with cell walls, the wall acts as a primary constraint of shape, and generation of specific cell shape depends on cytoskeletal organization for wall deposition and/or cell expansion. In

  19. Impact of Concanavalin-A-Mediated Cytoskeleton Disruption on Low-Density Lipoprotein Receptor-Related Protein-1 Internalization and Cell Surface Expression in Glioblastomas

    Science.gov (United States)

    Nanni, Samuel Burke; Pratt, Jonathan; Beauchemin, David; Haidara, Khadidja; Annabi, Borhane

    2016-01-01

    The low-density lipoprotein receptor-related protein 1 (LRP-1) is a multiligand endocytic receptor, which plays a pivotal role in controlling cytoskeleton dynamics during cancer cell migration. Its rapid endocytosis further allows efficient clearance of extracellular ligands. Concanavalin-A (ConA) is a lectin used to trigger in vitro physiological cellular processes, including cytokines secretion, nitric oxide production, and T-lymphocytes activation. Given that ConA exerts part of its effects through cytoskeleton remodeling, we questioned whether it affected LRP-1 expression, intracellular trafficking, and cell surface function in grade IV U87 glioblastoma cells. Using flow cytometry and confocal microscopy, we found that loss of the cell surface 600-kDa mature form of LRP-1 occurs upon ConA treatment. Consequently, internalization of the physiological α2-macroglobulin and the synthetic angiopep-2 ligands of LRP-1 was also decreased. Silencing of known mediators of ConA, such as the membrane type-1 matrix metalloproteinase, and the Toll-like receptors (TLR)-2 and TLR-6 was unable to rescue ConA-mediated LRP-1 expression decrease, implying that the loss of LRP-1 was independent of cell surface relayed signaling. The ConA-mediated reduction in LRP-1 expression was emulated by the actin cytoskeleton-disrupting agent cytochalasin-D, but not by the microtubule inhibitor nocodazole, and required both lysosomal- and ubiquitin-proteasome system-mediated degradation. Our study implies that actin cytoskeleton integrity is required for proper LRP-1 cell surface functions and that impaired trafficking leads to specialized compartmentation and degradation. Our data also strengthen the biomarker role of cell surface LRP-1 functions in the vectorized transport of therapeutic angiopep bioconjugates into brain cancer cells.

  20. Correlated light and electron microscopy observations of the uterine epithelial cell actin cytoskeleton using fluorescently labeled resin-embedded sections.

    Science.gov (United States)

    Moore, Chad L; Cheng, Delfine; Shami, Gerald J; Murphy, Christopher R

    2016-05-01

    In order to perform correlative light and electron microscopy (CLEM) more precisely, we have modified existing specimen preparation protocols allowing fluorescence retention within embedded and sectioned tissue, facilitating direct observation across length scales. We detail a protocol which provides a precise correlation accuracy using accessible techniques in biological specimen preparation. By combining a pre-embedding uranyl acetate staining step with the progressive lowering of temperature (PLT) technique, a methacrylate embedded tissue specimen is ultrathin sectioned and mounted onto a TEM finder grid for immediate viewing in the confocal and electron microscope. In this study, the protocol is applied to rat uterine epithelial cells in vivo during early pregnancy. Correlative overlay data was used to track changes in filamentous actin that occurs in these cells from fertilization (Day 1) to implantation on Day 6 as part of the plasma membrane transformation, a process essential in the development of uterine receptivity in the rat. CLEM confirmed that the actin cytoskeleton is disrupted as apical microvilli are progressively lost toward implantation, and revealed the thick and continuous terminal web is replaced by a thinner and irregular actin band, with individually distinguishable filaments connecting actin meshworks which correspond with remaining plasma membrane protrusions. PMID:26930006

  1. Host Cell Invasion by Toxoplasma gondii Is Temporally Regulated by the Host Microtubule Cytoskeleton ▿ †

    OpenAIRE

    Sweeney, Kristin R.; Morrissette, Naomi S.; LaChapelle, Stephanie; Blader, Ira J.

    2010-01-01

    Toxoplasma gondii is an obligate intracellular protozoan parasite that invades and replicates within most nucleated cells of warm-blooded animals. The basis for this wide host cell tropism is unknown but could be because parasites invade host cells using distinct pathways and/or repertoires of host factors. Using synchronized parasite invasion assays, we found that host microtubule disruption significantly reduces parasite invasion into host cells early after stimulating parasite invasion but...

  2. Actin Cytoskeleton Manipulation by Effector Proteins Secreted by Diarrheagenic Escherichia coli Pathotypes

    Directory of Open Access Journals (Sweden)

    Fernando Navarro-Garcia

    2013-01-01

    Full Text Available The actin cytoskeleton is a dynamic structure necessary for cell and tissue organization, including the maintenance of epithelial barriers. Disruption of the epithelial barrier coincides with alterations of the actin cytoskeleton in several disease states. These disruptions primarily affect the paracellular space, which is normally regulated by tight junctions. Thereby, the actin cytoskeleton is a common and recurring target of bacterial virulence factors. In order to manipulate the actin cytoskeleton, bacteria secrete and inject toxins and effectors to hijack the host cell machinery, which interferes with host-cell pathways and with a number of actin binding proteins. An interesting model to study actin manipulation by bacterial effectors is Escherichia coli since due to its genome plasticity it has acquired diverse genetic mobile elements, which allow having different E. coli varieties in one bacterial species. These E. coli pathotypes, including intracellular and extracellular bacteria, interact with epithelial cells, and their interactions depend on a specific combination of virulence factors. In this paper we focus on E. coli effectors that mimic host cell proteins to manipulate the actin cytoskeleton. The study of bacterial effector-cytoskeleton interaction will contribute not only to the comprehension of the molecular causes of infectious diseases but also to increase our knowledge of cell biology.

  3. Protein kinase C delta-mediated cytoskeleton remodeling is involved in aloe-emodin-induced photokilling of human lung cancer cells.

    Science.gov (United States)

    Chang, Wen-Te; You, Bang-Jau; Yang, Wen-Hui; Wu, Chi-Yu; Bau, Da-Tian; Lee, Hong-Zin

    2012-09-01

    Photodynamic therapy is becoming a widely accepted form of cancer treatment using a photosensitizing agent and light. Our previous study has demonstrated that photoactivated aloe-emodin induced anoikis and changes in cell morphology, which were in part mediated through its effect on cytoskeleton in lung carcinoma H460 cells. However, the molecular mechanisms of these photoactivated aloe-emodin-induced changes remain unknown. The present study demonstrated that the expression of protein kinase Cδ (PKCδ) was triggered by aloe-emodin and irradiation in H460 cells. Furthermore, the photoactivated aloe-emodin-induced cell death and translocation of PKCδ from the cytosol to the nucleus was found to be significantly inhibited by rottlerin, a PKCδ-selective inhibitor. Western blot analysis demonstrated that rottlerin also reversed the decrease in protein expression of cytoskeleton-related proteins, such as rat sarcoma (RAS), ras homolog gene family member A (RHO), p38, heat shock protein 27 (HSP27), focal adhesion kinase (FAK), α-actinin and tubulin, induced by photoactivated aloe-emodin. Our findings suggest that the regulation of cytoskeleton-related proteins mediated by PKCδ may be the mechanisms for the protective effects of rottlerin against the photoactivated aloe-emodin induced H460 cell death. PMID:22993309

  4. Nanostructured Organic Solar Cells

    DEFF Research Database (Denmark)

    Radziwon, Michal Jędrzej; Rubahn, Horst-Günter; Madsen, Morten

    Recent forecasts for alternative energy generation predict emerging importance of supporting state of art photovoltaic solar cells with their organic equivalents. Despite their significantly lower efficiency, number of application niches are suitable for organic solar cells. This work reveals...... the principles of bulk heterojunction organic solar cells fabrication as well as summarises major differences in physics of their operation....

  5. Dictyostelium Dock180-related RacGEFs Regulate the Actin Cytoskeleton during Cell Motility

    OpenAIRE

    Para, Alessia; Krischke, Miriam; Merlot, Sylvain; Shen, Zhouxin; Oberholzer, Michael; Lee, Susan; Briggs, Steven; Firtel, Richard A.

    2009-01-01

    Cell motility of amoeboid cells is mediated by localized F-actin polymerization that drives the extension of membrane protrusions to promote forward movements. We show that deletion of either of two members of the Dictyostelium Dock180 family of RacGEFs, DockA and DockD, causes decreased speed of chemotaxing cells. The phenotype is enhanced in the double mutant and expression of DockA or DockD complements the reduced speed of randomly moving DockD null cells' phenotype, suggesting that DockA ...

  6. Chaetoglobosin A preferentially induces apoptosis in chronic lymphocytic leukemia cells by targeting the cytoskeleton

    DEFF Research Database (Denmark)

    Knudsen, Peter Boldsen; Hanna, B.; Ohl, S.;

    2013-01-01

    family that showed preferential induction of apoptosis in CLL cells, even under culture conditions that mimic lymphoid tissues. In vitro testing of 89 CLL cases revealed effective targeting of CLL cells by Chaetoglobosin A, independent of bad prognosis characteristics, like 17p deletion or TP53 mutation...... novel drugs that target CLL cells also in protective microenvironments, we performed a fungal extract screen using cocultures of primary CLL cells with bone marrow-derived stromal cells. A metabolite produced by Penicillium aquamarinium was identified as Chaetoglobosin A, a member of the cytochalasan...... treatment with PI3K and BTK inhibitors, suggesting this compound as a novel potential drug for CLL.Leukemia accepted article preview online, 27 November 2013. doi:10.1038/leu.2013.360....

  7. Shear-induced reorganization of renal proximal tubule cell actin cytoskeleton and apical junctional complexes.

    Science.gov (United States)

    Duan, Yi; Gotoh, Nanami; Yan, Qingshang; Du, Zhaopeng; Weinstein, Alan M; Wang, Tong; Weinbaum, Sheldon

    2008-08-12

    In this study, we demonstrate that fluid shear stress (FSS)-induced actin cytoskeletal reorganization and junctional formation in renal epithelial cells are nearly completely opposite the corresponding changes in vascular endothelial cells (ECs) [Thi MM et al. (2004) Proc Natl Acad Sci USA 101:16483-16488]. Mouse proximal tubule cells (PTCs) were subjected to 5 h of FSS (1 dyn/cm(2)) to investigate the dynamic responses of the cytoskeletal distribution of filamentous actin (F-actin), ZO-1, E-cadherin, vinculin, and paxillin to FSS. Immunofluorescence analysis revealed that FSS caused basal stress fiber disruption, more densely distributed peripheral actin bands (DPABs), and the formation of both tight junctions (TJs) and adherens junctions (AJs). A dramatic reinforcement of vinculin staining was found at the cell borders as well as the cell interior. These responses were abrogated by the actin-disrupting drug, cytochalasin D. To interpret these results, we propose a "junctional buttressing" model for PTCs in which FSS enables the DPABs, TJs, and AJs to become more tightly connected. In contrast, in the "bumper-car" model for ECs, all junctional connections were severely disrupted by FSS. This "junctional buttressing" model explains why a FSS of only 1/10 of that used in the EC study can cause a similarly dramatic, cytoskeletal response in these tall, cuboidal epithelial cells; and why junctional buttressing between adjacent cells may benefit renal epithelium in maximizing flow-activated, brush border-dependent, transcellular salt and water reabsorption. PMID:18685100

  8. Identification of cytoskeleton-associated proteins essential for lysosomal stability and survival of human cancer cells

    DEFF Research Database (Denmark)

    Groth-Pedersen, Line; Aits, Sonja; Corcelle-Termeau, Elisabeth;

    2012-01-01

    Microtubule-disturbing drugs inhibit lysosomal trafficking and induce lysosomal membrane permeabilization followed by cathepsin-dependent cell death. To identify specific trafficking-related proteins that control cell survival and lysosomal stability, we screened a molecular motor siRNA library in...... human MCF7 breast cancer cells. SiRNAs targeting four kinesins (KIF11/Eg5, KIF20A, KIF21A, KIF25), myosin 1G (MYO1G), myosin heavy chain 1 (MYH1) and tropomyosin 2 (TPM2) were identified as effective inducers of non-apoptotic cell death. The cell death induced by KIF11, KIF21A, KIF25, MYH1 or TPM2 si......, MYH1, TPM2), increased dextran accumulation (KIF20A), or reduced autophagic flux (MYO1G, MYH1). Importantly, all seven siRNAs also killed human cervix cancer (HeLa) and osteosarcoma (U-2-OS) cells and sensitized cancer cells to other lysosome-destabilizing treatments, i.e. photo-oxidation, siramesine...

  9. CADM1 controls actin cytoskeleton assembly and regulates extracellular matrix adhesion in human mast cells.

    Directory of Open Access Journals (Sweden)

    Elena P Moiseeva

    Full Text Available CADM1 is a major receptor for the adhesion of mast cells (MCs to fibroblasts, human airway smooth muscle cells (HASMCs and neurons. It also regulates E-cadherin and alpha6beta4 integrin in other cell types. Here we investigated a role for CADM1 in MC adhesion to both cells and extracellular matrix (ECM. Downregulation of CADM1 in the human MC line HMC-1 resulted not only in reduced adhesion to HASMCs, but also reduced adhesion to their ECM. Time-course studies in the presence of EDTA to inhibit integrins demonstrated that CADM1 provided fast initial adhesion to HASMCs and assisted with slower adhesion to ECM. CADM1 downregulation, but not antibody-dependent CADM1 inhibition, reduced MC adhesion to ECM, suggesting indirect regulation of ECM adhesion. To investigate potential mechanisms, phosphotyrosine signalling and polymerisation of actin filaments, essential for integrin-mediated adhesion, were examined. Modulation of CADM1 expression positively correlated with surface KIT levels and polymerisation of cortical F-actin in HMC-1 cells. It also influenced phosphotyrosine signalling and KIT tyrosine autophosphorylation. CADM1 accounted for 46% of surface KIT levels and 31% of F-actin in HMC-1 cells. CADM1 downregulation resulted in elongation of cortical actin filaments in both HMC-1 cells and human lung MCs and increased cell rigidity of HMC-1 cells. Collectively these data suggest that CADM1 is a key adhesion receptor, which regulates MC net adhesion, both directly through CADM1-dependent adhesion, and indirectly through the regulation of other adhesion receptors. The latter is likely to occur via docking of KIT and polymerisation of cortical F-actin. Here we propose a stepwise model of adhesion with CADM1 as a driving force for net MC adhesion.

  10. The geodiamolide H, derived from Brazilian sponge Geodia corticostylifera, regulates actin cytoskeleton, migration and invasion of breast cancer cells cultured in three-dimensional environment.

    Science.gov (United States)

    Freitas, Vanessa M; Rangel, Marisa; Bisson, Letícia F; Jaeger, Ruy G; Machado-Santelli, Gláucia M

    2008-09-01

    We are investigating effects of the depsipeptide geodiamolide H, isolated from the Brazilian sponge Geodia corticostylifera, on cancer cell lines grown in 3D environment. As shown previously geodiamolide H disrupts actin cytoskeleton in both sea urchin eggs and breast cancer cell monolayers. We used a normal mammary epithelial cell line MCF 10A that in 3D assay results formation of polarized spheroids. We also used cell lines derived from breast tumors with different degrees of differentiation: MCF7 positive for estrogen receptor and the Hs578T, negative for hormone receptors. Cells were placed on top of Matrigel. Spheroids obtained from these cultures were treated with geodiamolide H. Control and treated samples were analyzed by light and confocal microscopy. Geodiamolide H dramatically affected the poorly differentiated and aggressive Hs578T cell line. The peptide reverted Hs578T malignant phenotype to polarized spheroid-like structures. MCF7 cells treated by geodiamolide H exhibited polarization compared to controls. Geodiamolide H induced striking phenotypic modifications in Hs578T cell line and disruption of actin cytoskeleton. We investigated effects of geodiamolide H on migration and invasion of Hs578T cells. Time-lapse microscopy showed that the peptide inhibited migration of these cells in a dose-dependent manner. Furthermore invasion assays revealed that geodiamolide H induced a 30% decrease on invasive behavior of Hs578T cells. Our results suggest that geodiamolide H inhibits migration and invasion of Hs578T cells probably through modifications in actin cytoskeleton. The fact that normal cell lines were not affected by treatment with geodiamolide H stimulates new studies towards therapeutic use for this peptide. PMID:18330887

  11. Effect of the ulcerogenic agents ethanol, acetylsalicylic acid and taurocholate on actin cytoskeleton and cell motility in cultured rat gastric mucosal cells

    Institute of Scientific and Technical Information of China (English)

    Siamak Bidel; Harri Mustonen; Giti Khalighi-Sikaroudi; Eero Lehtonen; Pauli Puolakkainen; Tuula Kiviluoto; Eero Kivilaakso

    2005-01-01

    AIM: To assess the effects of ulcerogenic agents on actin cytoskeleton and cell motility and the contribution of oxidative stress.METHODS: Rat gastric mucosal cell monolayers were cultured on coverslips. The cells were exposed, with or without allopurinol (2 mmol/L), for 15 min to ethanol (10-150 mL/L), ASA (1-20 mmol/L) or taurocholate (1-20 mmol/L), then the cells were processed for actin and vinculin staining. Cell migration after wounding was also measured.RESULTS: Exposure to 10 mL/L ethanol caused divergence of zonula adherens-associated actin bundles of adjacent cells and decreased rate of migration. These actions were opposed by xanthine oxidase inhibitor allopurinol. Exposure to 50 mL/L ethanol induced degradation and divergence of zonula adherens-associated vinculin from adjacent cells,which was, again, partially reverted by allopurinol. With 1 mmol/L ASA actin filaments became shorter and thicker.However, higher concentrations (10, 20 mmol/L) of ASA returned microfilaments thinner and longer, and decreased rate of migration. Zonula adherens-associated actin bundles were moderately distorted with 10 mmol/L ASA and with 10 mmol/L taurocholate. Exposure to taurocholate provoked changes resembling those of ASA. Taurocholate 5-20 mmol/L decreased the rate of migration dose dependently. The effects of ASA and taurocholate were not prevented by allopurinol.CONCLUSION: All ulcerogenic agents decreased the rate of migration dose dependently and induced divergence of zonula adherens-associated actin bundles of adjacent cells.In addition, ethanol and ASA caused degradation of actin cytoskeleton. Oxidative stress seems to underlie ethanol,but not ASA or taurocholate, induced cytoskeletal damage.

  12. STIM1-cytoskeleton cross-talk in mast cell degranulation and chemotaxis

    Czech Academy of Sciences Publication Activity Database

    Dráber, Petr

    Southampton, 2011. [International Mast Cell and Basophil Meeting 2011 in partnership to the COST Annual Conference on Mast Cells and Basophils 2011. Southampton (GB), 24.11.2011-25.11.2011] R&D Projects: GA ČR GA301/09/1826; GA ČR GAP302/10/1759 Institutional research plan: CEZ:AV0Z50520514 Keywords : STIM1 * chemotaxe * žírná buňka Subject RIV: EB - Genetics ; Molecular Biology

  13. Cytoskeleton proteins previously considered exclusive to Ganglion Cells are transiently expressed by all retinal neuronal precursors

    OpenAIRE

    Canto-Soler M Valeria; McNally Minda; Gutierrez Christian

    2011-01-01

    Abstract Background Understanding the mechanisms governing cell fate specification remains one of the main challenges in the study of retinal development. In this context, molecular markers that identify specific cell types become crucial tools for the analysis and interpretation of these phenomena. In studies using the developing chick retina, expression of the mid-size neurofilament (NF-M) and a chick-specific microtubule associated protein recognized by the RA4 antibody (MAP(RA4)), have be...

  14. Identification of cytoskeleton-associated proteins essential for lysosomal stability and survival of human cancer cells.

    Science.gov (United States)

    Groth-Pedersen, Line; Aits, Sonja; Corcelle-Termeau, Elisabeth; Petersen, Nikolaj H T; Nylandsted, Jesper; Jäättelä, Marja

    2012-01-01

    Microtubule-disturbing drugs inhibit lysosomal trafficking and induce lysosomal membrane permeabilization followed by cathepsin-dependent cell death. To identify specific trafficking-related proteins that control cell survival and lysosomal stability, we screened a molecular motor siRNA library in human MCF7 breast cancer cells. SiRNAs targeting four kinesins (KIF11/Eg5, KIF20A, KIF21A, KIF25), myosin 1G (MYO1G), myosin heavy chain 1 (MYH1) and tropomyosin 2 (TPM2) were identified as effective inducers of non-apoptotic cell death. The cell death induced by KIF11, KIF21A, KIF25, MYH1 or TPM2 siRNAs was preceded by lysosomal membrane permeabilization, and all identified siRNAs induced several changes in the endo-lysosomal compartment, i.e. increased lysosomal volume (KIF11, KIF20A, KIF25, MYO1G, MYH1), increased cysteine cathepsin activity (KIF20A, KIF25), altered lysosomal localization (KIF25, MYH1, TPM2), increased dextran accumulation (KIF20A), or reduced autophagic flux (MYO1G, MYH1). Importantly, all seven siRNAs also killed human cervix cancer (HeLa) and osteosarcoma (U-2-OS) cells and sensitized cancer cells to other lysosome-destabilizing treatments, i.e. photo-oxidation, siramesine, etoposide or cisplatin. Similarly to KIF11 siRNA, the KIF11 inhibitor monastrol induced lysosomal membrane permeabilization and sensitized several cancer cell lines to siramesine. While KIF11 inhibitors are under clinical development as mitotic blockers, our data reveal a new function for KIF11 in controlling lysosomal stability and introduce six other molecular motors as putative cancer drug targets. PMID:23071517

  15. Continuous-Wave Stimulated Emission Depletion Microscope for Imaging Actin Cytoskeleton in Fixed and Live Cells

    Directory of Open Access Journals (Sweden)

    Bhanu Neupane

    2015-09-01

    Full Text Available Stimulated emission depletion (STED microscopy provides a new opportunity to study fine sub-cellular structures and highly dynamic cellular processes, which are challenging to observe using conventional optical microscopy. Using actin as an example, we explored the feasibility of using a continuous wave (CW-STED microscope to study the fine structure and dynamics in fixed and live cells. Actin plays an important role in cellular processes, whose functioning involves dynamic formation and reorganization of fine structures of actin filaments. Frequently used confocal fluorescence and STED microscopy dyes were employed to image fixed PC-12 cells (dyed with phalloidin- fluorescein isothiocyante and live rat chondrosarcoma cells (RCS transfected with actin-green fluorescent protein (GFP. Compared to conventional confocal fluorescence microscopy, CW-STED microscopy shows improved spatial resolution in both fixed and live cells. We were able to monitor cell morphology changes continuously; however, the number of repetitive analyses were limited primarily by the dyes used in these experiments and could be improved with the use of dyes less susceptible to photobleaching. In conclusion, CW-STED may disclose new information for biological systems with a proper characteristic length scale. The challenges of using CW-STED microscopy to study cell structures are discussed.

  16. Comparison of the cell cytoskeleton in migratory and stationary chick fibroblasts

    DEFF Research Database (Denmark)

    Badley, R A; Couchman, J R; Rees, D A

    1980-01-01

    The organization of the principal cytoskeletal components (actin, tubulin and 10 nm filament protein) have been compared by immunofluorescence microscopy in two populations of chick heart fibroblasts, previously shown to be adapted respectively for rapid, directed migration or adhesion and growth...

  17. Disruption of spectrin-like cytoskeleton in differentiating keratinocytes by PKCδ activation is associated with phosphorylated adducin.

    Directory of Open Access Journals (Sweden)

    Kong-Nan Zhao

    Full Text Available Spectrin is a central component of the cytoskeletal protein network in a variety of erythroid and non-erythroid cells. In keratinocytes, this protein has been shown to be pericytoplasmic and plasma membrane associated, but its characteristics and function have not been established in these cells. Here we demonstrate that spectrin increases dramatically in amount and is assembled into the cytoskeleton during differentiation in mouse and human keratinocytes. The spectrin-like cytoskeleton was predominantly organized in the granular and cornified layers of the epidermis and disrupted by actin filament inhibitors, but not by anti-mitotic drugs. When the cytoskeleton was disrupted PKCδ was activated by phosphorylation on Thr505. Specific inhibition of PKCδ(Thr505 activation with rottlerin prevented disruption of the spectrin-like cytoskeleton and the associated morphological changes that accompany differentiation. Rottlerin also inhibited specific phosphorylation of the PKCδ substrate adducin, a cytoskeletal protein. Furthermore, knock-down of endogenous adducin affected not only expression of adducin, but also spectrin and PKCδ, and severely disrupted organization of the spectrin-like cytoskeleton and cytoskeletal distribution of both adducin and PKCδ. These results demonstrate that organization of a spectrin-like cytoskeleton is associated with keratinocytes differentiation, and disruption of this cytoskeleton is mediated by either PKCδ(Thr505 phosphorylation associated with phosphorylated adducin or due to reduction of endogenous adducin, which normally connects and stabilizes the spectrin-actin complex.

  18. Cadmium toxicity: Effects on cytoskeleton, vesicular trafficking and cell wall construction

    OpenAIRE

    Wan, Lichuan; Zhang, Haiyan

    2012-01-01

    Cadmium is a well-known environmental pollutant with distinctly toxic effects on plants. It can displace certain essential metals from a wealth of metalloproteins, and thus disturb many normal physiological processes and cause severe developmental aberrant. The harmful effects of cadmium stress include, but are not limited to: reactive oxygen species overproduction, higher lipid hydroperoxide contents, and chloroplast structure change, which may lead to cell death. Plants have developed diver...

  19. Cell proliferation, cell shape, and microtubule and cellulose microfibril organization of tobacco BY-2 cells are not altered by exposure to near weightlessness in space.

    Science.gov (United States)

    Sieberer, Björn J; Kieft, Henk; Franssen-Verheijen, Tiny; Emons, Anne Mie C; Vos, Jan W

    2009-11-01

    The microtubule cytoskeleton and the cell wall both play key roles in plant cell growth and division, determining the plant's final stature. At near weightlessness, tubulin polymerizes into microtubules in vitro, but these microtubules do not self-organize in the ordered patterns observed at 1g. Likewise, at near weightlessness cortical microtubules in protoplasts have difficulty organizing into parallel arrays, which are required for proper plant cell elongation. However, intact plants do grow in space and therefore should have a normally functioning microtubule cytoskeleton. Since the main difference between protoplasts and plant cells in a tissue is the presence of a cell wall, we studied single, but walled, tobacco BY-2 suspension-cultured cells during an 8-day space-flight experiment on board of the Soyuz capsule and the International Space Station during the 12S mission (March-April 2006). We show that the cortical microtubule density, ordering and orientation in isolated walled plant cells are unaffected by near weightlessness, as are the orientation of the cellulose microfibrils, cell proliferation, and cell shape. Likely, tissue organization is not essential for the organization of these structures in space. When combined with the fact that many recovering protoplasts have an aberrant cortical microtubule cytoskeleton, the results suggest a role for the cell wall, or its production machinery, in structuring the microtubule cytoskeleton. PMID:19756725

  20. Role of surface nickel content on human cell cytoskeleton formation on Nitinol

    OpenAIRE

    W. Chrzanowski; Szade, J.; Hart, A. D.; Armitage, D. A.; Dalby, M. J.; Knowles, J. C.

    2009-01-01

    Cell activity on an implant surface can be modulated by cues such as topography, chemistry or stiffness(1,2). For Ni-Ti alloy this is achieved mainly by alteration in chemistry. However, high nickel concentrations may be a concern in the use Nitinol on a larger scale. Current reports on Nitinol bring contradictory data(3-5) suggesting that high nickel content is not particularly dangerous and nickel-titanium alloys are safe to be used. On the other hand it was shown that nickel has a toxic ef...

  1. Membrane-Cytoskeleton Dynamics in the Course of Mast Cell Activation

    Czech Academy of Sciences Publication Activity Database

    Dráber, Pavel; Dráber, Petr

    2015-01-01

    Roč. 1220, č. 1 (2015), s. 219-237. ISSN 1064-3745 R&D Projects: GA ČR GA204/09/1777; GA ČR(CZ) GA14-09807S; GA ČR(CZ) GA14-00703S; GA ČR(CZ) GBP302/12/G101; GA MŠk LC545; GA MŠk LD12073; GA MŠk(CZ) LD13015; GA AV ČR KAN200520701; GA AV ČR(CZ) M200520901 Institutional support: RVO:68378050 Keywords : mast cells * plasma membrane * actin Subject RIV: EB - Genetics ; Molecular Biology

  2. Overexpression of amyloid precursor protein inhibits neurite outgrowth and disrupts cytoskeleton in N2a cells

    Institute of Scientific and Technical Information of China (English)

    王泽芬; 王建枝

    2004-01-01

    @@ There is considerable evidence suggesting that altered metabolism of β-amyloid precursor protein (APP) and accumulation of its β-amyloid (Aβ) fragment are key features of Alzheimer's disease (AD). APP is a type Ⅰ integral membrane protein and consists of 695-770 amino acids encoded by differentially spliced mRNAs transcribed from a single gene located on human chromosome 21.1 The 695-amino acid APP is expressed preferentially in the brain. Aβ, the major component of senile plaques, is derived by proteolytic processing of APP by β-and γ-secretase and is constitutively released from most cells.

  3. Porcine reproductive and respiratory syndrome virus (PRRSV infection spreads by cell-to-cell transfer in cultured MARC-145 cells, is dependent on an intact cytoskeleton, and is suppressed by drug-targeting of cell permissiveness to virus infection

    Directory of Open Access Journals (Sweden)

    Rowland Raymond RR

    2006-11-01

    Full Text Available Abstract Background Porcine reproductive and respiratory syndrome virus (PRRSV is the etiologic agent of PRRS, causing widespread chronic infections which are largely uncontrolled by currently available vaccines or other antiviral measures. Cultured monkey kidney (MARC-145 cells provide an important tool for the study of PRRSV replication. For the present study, flow cytometric and fluorescence antibody (FA analyses of PRRSV infection of cultured MARC-145 cells were carried out in experiments designed to clarify viral dynamics and the mechanism of viral spread. The roles of viral permissiveness and the cytoskeleton in PRRSV infection and transmission were examined in conjunction with antiviral and cytotoxic drugs. Results Flow cytometric and FA analyses of PRRSV antigen expression revealed distinct primary and secondary phases of MARC-145 cell infection. PRRSV antigen was randomly expressed in a few percent of cells during the primary phase of infection (up to about 20–22 h p.i., but the logarithmic infection phase (days 2–3 p.i., was characterized by secondary spread to clusters of infected cells. The formation of secondary clusters of PRRSV-infected cells preceded the development of CPE in MARC-145 cells, and both primary and secondary PRRSV infection were inhibited by colchicine and cytochalasin D, demonstrating a critical role of the cytoskeleton in viral permissiveness as well as cell-to-cell transmission from a subpopulation of cells permissive for free virus to secondary targets. Cellular expression of actin also appeared to correlate with PRRSV resistance, suggesting a second role of the actin cytoskeleton as a potential barrier to cell-to-cell transmission. PRRSV infection and cell-to-cell transmission were efficiently suppressed by interferon-γ (IFN-γ, as well as the more-potent experimental antiviral agent AK-2. Conclusion The results demonstrate two distinct mechanisms of PRRSV infection: primary infection of a relatively small

  4. The cytoskeleton proteins and LH-regulated steroidogenesis in porcine luteal cells

    Energy Technology Data Exchange (ETDEWEB)

    Gregoraszczuk, Ewa L.; Slomczynska, Maria [Uniwersytet Jagiellonski, Cracow (Poland)

    1996-12-31

    The involvement of microtubules (MT) and microflilaments (MF) in LH-regulation of luteal cell stereoidogenesis was assessed at the middle stage of corpus luteum development. The influence microtubule- and microfilament-altering agents on basal and LH-stimulated progesterone (P4) production and secretion into the incubation medium was determined by RIA. LH-stimulated P4 production was 2.5 times higher than in the control cultures. Cytochalasis B (Cyt B) was without effect on basal P4 synthesis but increased the basal fraction of P4 secreted into the incubation medium, while colchicine (Col) increased both basal P4 synthesis and the fraction of P4 secreted into the incubation medium. LH-stimulated progesterone synthesis was reduced by Col, but the fraction secreted into the incubation medium increased. Cyt B had no effect on LH-stimulated synthesis but it decreased the fraction of P4 secreted into the incubation medium. Our findings demonstrate significant differences in the effect of Cyt B and Col on steroidogenesis in corpus luteum. We conclude that microtubules play an important role in the process of LH-stimulated P4 synthesis, while microfilaments act in the process of basal and LH-stimulated P4 secretion. (author). 23 refs, 4 figs.

  5. Actin cytoskeleton-dependent pathways for ADMA-induced NF-κB activation and TGF-β high expression in human renal glomerular endothelial cells

    Institute of Scientific and Technical Information of China (English)

    Liyan Wang; Dongliang Zhang; Junfang Zheng; Yiduo Feng; Yu Zhang; Wenhu Liu

    2012-01-01

    Asymmetric dimethylarginine (ADMA),an endogenous nitric oxide synthase inhibitor,is considered to be an independent risk factor in the progression of chronic kidney diseases (CKD).It can induce kidney fibrosis by increasing transforming growth factor (TGF)-β1 expression,but its molecular mechanism is unclear.The aim of the present study was to investigate the role of actin cytoskeleton in ADMA-induced TGF-β1 high expression in human renal glomerular endothelial cells (HRGECs).The structure of stress fibers was visualized by immunofluorescence,nuclear factor-κB (NF-κB) DNA-binding activity was assessed by an electrophoretic mobility shift assay and TGF-β1 expression was assessed by western blot analysis.Results showed that ADMA induced the assembly of stress fibers,DNA binding of NF-κB,and increasing expression of TGF-β1.When the dynamics of actin cytoskeleton was perturbed by the actin-depolymerizing agent cytochalasin D and the actin-stabilizing agent jasplakinolide,or ablation of stress fiber bundles by the nicotineamide adenine dinucleotide phosphate oxidase inhibitor apocynin and p38 mitogen-activated protein kinase inhibitor SB203580,ADMA-induced DNA binding of NF-κB and TGF-β1 expression were inhibited.These results revealed an actin cytoskeleton-dependent mechanism in ADMA-induced NF-κB activation and TGF-β1 high expression in HRGECs.The specific targeting of the actin cytoskeleton may be a useful strategy to prevent ADMA-activated kidney fibrosis in CKD.

  6. Hypothyroidism decreases proinsulin gene expression and the attachment of its mRNA and eEF1A protein to the actin cytoskeleton of INS-1E cells

    Directory of Open Access Journals (Sweden)

    F. Goulart-Silva

    2011-10-01

    Full Text Available The actions of thyroid hormone (TH on pancreatic beta cells have not been thoroughly explored, with current knowledge being limited to the modulation of insulin secretion in response to glucose, and beta cell viability by regulation of pro-mitotic and pro-apoptotic factors. Therefore, the effects of TH on proinsulin gene expression are not known. This led us to measure: a proinsulin mRNA expression, b proinsulin transcripts and eEF1A protein binding to the actin cytoskeleton, c actin cytoskeleton arrangement, and d proinsulin mRNA poly(A tail length modulation in INS-1E cells cultured in different media containing: i normal fetal bovine serum - FBS (control; ii normal FBS plus 1 µM or 10 nM T3, for 12 h, and iii FBS depleted of TH for 24 h (Tx. A decrease in proinsulin mRNA content and attachment to the cytoskeleton were observed in hypothyroid (Tx beta cells. The amount of eEF1A protein anchored to the cytoskeleton was also reduced in hypothyroidism, and it is worth mentioning that eEF1A is essential to attach transcripts to the cytoskeleton, which might modulate their stability and rate of translation. Proinsulin poly(A tail length and cytoskeleton arrangement remained unchanged in hypothyroidism. T3 treatment of control cells for 12 h did not induce any changes in the parameters studied. The data indicate that TH is important for proinsulin mRNA expression and translation, since its total amount and attachment to the cytoskeleton are decreased in hypothyroid beta cells, providing evidence that effects of TH on carbohydrate metabolism also include the control of proinsulin gene expression.

  7. Purification of an 80,000-dalton protein that is a component of the isolated microvillus cytoskeleton, and its localization in nonmuscle cells

    OpenAIRE

    1983-01-01

    The microvillus cytoskeleton, isolated from chicken intestinal epithelial cell brush borders, is known to contain five major protein components, the 110,000-dalton polypeptide, villin (95,000 daltons), fimbrin (68,000 daltons), actin (43,000 daltons), and calmodulin (17,000 daltons). In this paper we describe our first step in studying the minor components of the isolated core. We have so far identified and purified an 80,000-dalton polypeptide that was present in the isolated structure in ap...

  8. Cyanamide mode of action during inhibition of onion (Allium cepa L.) root growth involves disturbances in cell division and cytoskeleton formation.

    Science.gov (United States)

    Soltys, Dorota; Rudzińska-Langwald, Anna; Kurek, Wojciech; Gniazdowska, Agnieszka; Sliwinska, Elwira; Bogatek, Renata

    2011-09-01

    Cyanamide is an allelochemical produced by hairy vetch (Vicia villosa Roth.). Its phyotoxic effect on plant growth was examined on roots of onion (Allium cepa L.) bulbs. Water solution of cyanamide (2-10 mM) restricted growth of onion roots in a dose-dependent manner. Treatment of onion roots with cyanamide resulted in a decrease in root growth rate accompanied by a decrease in accumulation of fresh and dry weight. The inhibitory effect of cyanamide was reversed by its removal from the environment, but full recovery was observed only for tissue treated with this chemical at low concentration (2-6 mM). Cytological observations of root tip cells suggest that disturbances in cell division may explain the strong cyanamide allelopathic activity. Moreover, in cyanamide-treated onion the following changes were detected: reduction of mitotic cells, inhibition of proliferation of meristematic cells and cell cycle, and modifications of cytoskeleton arrangement. PMID:21573814

  9. Growth dynamics and cytoskeleton organization during stem maturation and gravity-induced stem bending in Zea mays L

    Science.gov (United States)

    Collings, D. A.; Winter, H.; Wyatt, S. E.; Allen, N. S.; Davies, E. (Principal Investigator)

    1998-01-01

    Characterization of gravitropic bending in the maize stem pulvinus, a tissue that functions specifically in gravity responses, demonstrates that the pulvinus is an ideal system for studying gravitropism. Gravistimulation during the second of three developmental phases of the pulvinus induces a gradient of cell elongation across the non-growing cells of the pulvinus, with the most elongation occurring on the lower side. This cell elongation is spatially and temporally separated from normal internodal cell elongation. The three characterized growth phases in the pulvinus correspond closely to a specialized developmental sequence in which structural features typical of cells not fully matured are retained while cell maturation occurs in surrounding internodal and nodal tissue. For example, the lignification of supporting tissue and rearrangement of transverse microtubules to oblique that occur in the internode when cell elongation ceases are delayed for up to 10 d in the adjacent cells of the pulvinus, and only occurs as a pulvinus loses its capacity to respond to gravistimulation. Gravistimulation does not modify this developmental sequence. Neither wall lignification nor rearrangement of transverse microtubules occurs in the rapidly elongating lower side or non-responsive upper side of the pulvinus until the pulvinus loses the capacity to bend further. Gravistimulation does, however, lead to the formation of putative pit fields within the expanding cells of the pulvinus.

  10. BCR and its mutants, the reciprocal t(9;22)-associated ABL/BCR fusion proteins, differentially regulate the cytoskeleton and cell motility

    International Nuclear Information System (INIS)

    The reciprocal (9;22) translocation fuses the bcr (breakpoint cluster region) gene on chromosome 22 to the abl (Abelson-leukemia-virus) gene on chromosome 9. Depending on the breakpoint on chromosome 22 (the Philadelphia chromosome – Ph+) the derivative 9+ encodes either the p40(ABL/BCR) fusion transcript, detectable in about 65% patients suffering from chronic myeloid leukemia, or the p96(ABL/BCR) fusion transcript, detectable in 100% of Ph+ acute lymphatic leukemia patients. The ABL/BCRs are N-terminally truncated BCR mutants. The fact that BCR contains Rho-GEF and Rac-GAP functions strongly suggest an important role in cytoskeleton modeling by regulating the activity of Rho-like GTPases, such as Rho, Rac and cdc42. We, therefore, compared the function of the ABL/BCR proteins with that of wild-type BCR. We investigated the effects of BCR and ABL/BCRs i.) on the activation status of Rho, Rac and cdc42 in GTPase-activation assays; ii.) on the actin cytoskeleton by direct immunofluorescence; and iii) on cell motility by studying migration into a three-dimensional stroma spheroid model, adhesion on an endothelial cell layer under shear stress in a flow chamber model, and chemotaxis and endothelial transmigration in a transwell model with an SDF-1α gradient. Here we show that both ABL/BCRs lost fundamental functional features of BCR regarding the regulation of small Rho-like GTPases with negative consequences on cell motility, in particular on the capacity to adhere to endothelial cells. Our data presented here describe for the first time an analysis of the biological function of the reciprocal t(9;22) ABL/BCR fusion proteins in comparison to their physiological counterpart BCR

  11. BCR and its mutants, the reciprocal t(9;22-associated ABL/BCR fusion proteins, differentially regulate the cytoskeleton and cell motility

    Directory of Open Access Journals (Sweden)

    Puccetti Elena

    2006-11-01

    Full Text Available Abstract Background The reciprocal (9;22 translocation fuses the bcr (breakpoint cluster region gene on chromosome 22 to the abl (Abelson-leukemia-virus gene on chromosome 9. Depending on the breakpoint on chromosome 22 (the Philadelphia chromosome – Ph+ the derivative 9+ encodes either the p40(ABL/BCR fusion transcript, detectable in about 65% patients suffering from chronic myeloid leukemia, or the p96(ABL/BCR fusion transcript, detectable in 100% of Ph+ acute lymphatic leukemia patients. The ABL/BCRs are N-terminally truncated BCR mutants. The fact that BCR contains Rho-GEF and Rac-GAP functions strongly suggest an important role in cytoskeleton modeling by regulating the activity of Rho-like GTPases, such as Rho, Rac and cdc42. We, therefore, compared the function of the ABL/BCR proteins with that of wild-type BCR. Methods We investigated the effects of BCR and ABL/BCRs i. on the activation status of Rho, Rac and cdc42 in GTPase-activation assays; ii. on the actin cytoskeleton by direct immunofluorescence; and iii on cell motility by studying migration into a three-dimensional stroma spheroid model, adhesion on an endothelial cell layer under shear stress in a flow chamber model, and chemotaxis and endothelial transmigration in a transwell model with an SDF-1α gradient. Results Here we show that both ABL/BCRs lost fundamental functional features of BCR regarding the regulation of small Rho-like GTPases with negative consequences on cell motility, in particular on the capacity to adhere to endothelial cells. Conclusion Our data presented here describe for the first time an analysis of the biological function of the reciprocal t(9;22 ABL/BCR fusion proteins in comparison to their physiological counterpart BCR.

  12. Sensor potency of the moonlighting enzyme-decorated cytoskeleton: the cytoskeleton as a metabolic sensor

    Directory of Open Access Journals (Sweden)

    Norris Vic

    2013-02-01

    Full Text Available Abstract Background There is extensive evidence for the interaction of metabolic enzymes with the eukaryotic cytoskeleton. The significance of these interactions is far from clear. Presentation of the hypothesis In the cytoskeletal integrative sensor hypothesis presented here, the cytoskeleton senses and integrates the general metabolic activity of the cell. This activity depends on the binding to the cytoskeleton of enzymes and, depending on the nature of the enzyme, this binding may occur if the enzyme is either active or inactive but not both. This enzyme-binding is further proposed to stabilize microtubules and microfilaments and to alter rates of GTP and ATP hydrolysis and their levels. Testing the hypothesis Evidence consistent with the cytoskeletal integrative sensor hypothesis is presented in the case of glycolysis. Several testable predictions are made. There should be a relationship between post-translational modifications of tubulin and of actin and their interaction with metabolic enzymes. Different conditions of cytoskeletal dynamics and enzyme-cytoskeleton binding should reveal significant differences in local and perhaps global levels and ratios of ATP and GTP. The different functions of moonlighting enzymes should depend on cytoskeletal binding. Implications of the hypothesis The physical and chemical effects arising from metabolic sensing by the cytoskeleton would have major consequences on cell shape, dynamics and cell cycle progression. The hypothesis provides a framework that helps the significance of the enzyme-decorated cytoskeleton be determined.

  13. Microfluidic devices for the study of actin cytoskeleton in constricted environments: Evidence for podosome formation in endothelial cells exposed to a confined slit.

    Science.gov (United States)

    Spuul, Pirjo; Chi, Pei-Yin; Billottet, Clotilde; Chou, Chia-Fu; Génot, Elisabeth

    2016-02-01

    The study of cell behavior in constricted environment is particularly relevant to our understanding of the mechanisms of cell invasion. In this regard, microfluidic systems offer promising platforms as microfabricated fluidic chips provide well-controlled physical, chemical and confined environments to study cell phenotype and behavior. Here, we report a fast and effective manufacturing process of user-friendly microfluidic chips ideally suited for quantitative live cell analysis in combination with immunofluorescence microscopy. The chip body, made of polydimethylsiloxane, is composed of two incubation chambers connected by one rectangular intermediate entry channel which provides access to a series of transversal slits where the observation can be made. The height of the slit is designed to be slightly smaller than that of the cells under study. To validate the chip performance, we analyzed the reorganization of the cytoskeleton of endothelial cells under various degree of spatial confinement. We illustrate how the constricted environment affects endothelial cell behavior in inducing the formation of podosomes. Moreover, the process was stimulated further when the surface of the slit was coated with a thin layer of fibronectin. The study demonstrates the suitability of this technological process for cost-effective fabrication of custom-made single-use chips for biological applications. PMID:26342258

  14. One isoform of Arg/Abl2 tyrosine kinase is nuclear and the other seven cytosolic isoforms differently modulate cell morphology, motility and the cytoskeleton

    Energy Technology Data Exchange (ETDEWEB)

    Bianchi, Cristina; Torsello, Barbara; Di Stefano, Vitalba; Zipeto, Maria A.; Facchetti, Rita; Bombelli, Silvia; Perego, Roberto A., E-mail: roberto.perego@unimib.it

    2013-08-01

    The non-receptor tyrosine kinase Abelson related gene (Arg/Abl2) regulates cell migration and morphogenesis by modulating the cytoskeleton. Arg promotes actin-based cell protrusions and spreading, and inhibits cell migration by attenuating stress fiber formation and contractility via activation of the RhoA inhibitor, p190RhoGAP, and by regulating focal adhesion dynamics also via CrkII phosphorylation. Eight full-length Arg isoforms with different N- and C-termini are endogenously expressed in human cells. In this paper, the eight Arg isoforms, subcloned in the pFLAG-CMV2 vector, were transfected in COS-7 cells in order to study their subcellular distribution and role in cell morphology, migration and cytoskeletal modulation. The transfected 1BSCTS Arg isoform has a nuclear distribution and phosphorylates CrkII in the nucleus, whilst the other isoforms are detected in the cytoplasm. The 1BLCTL, 1BSCTL, 1ASCTS isoforms were able to significantly decrease stress fibers, induce cell shrinkage and filopodia-like protrusions with a significant increase in p190RhoGAP phosphorylation. In contrast, 1ALCTL, 1ALCTS, 1ASCTL and 1BLCTS isoforms do not significantly decrease stress fibers and induce the formation of retraction tail-like protrusions. The 1BLCTL and 1ALCTL isoforms have different effects on cell migration and focal adhesions. All these data may open new perspectives to study the mechanisms of cell invasiveness. -Highlights: • Each of the eight Arg isoforms was transfected in COS-7 cells. • Only the 1BSCTS Arg isoform has a nuclear distribution in transfected cells. • The cytoplasmic isoforms and F-actin colocalize cortically and in cell protrusions. • Arg isoforms differently phosphorylate p190RhoGAP and CrkII. • Arg isoforms differently modulate stress fibers, cell protrusions and motility.

  15. A spatiotemporal characterization method for the dynamic cytoskeleton.

    Science.gov (United States)

    Alhussein, Ghada; Shanti, Aya; Farhat, Ilyas A H; Timraz, Sara B H; Alwahab, Noaf S A; Pearson, Yanthe E; Martin, Matthew N; Christoforou, Nicolas; Teo, Jeremy C M

    2016-05-01

    The significant gap between quantitative and qualitative understanding of cytoskeletal function is a pressing problem; microscopy and labeling techniques have improved qualitative investigations of localized cytoskeleton behavior, whereas quantitative analyses of whole cell cytoskeleton networks remain challenging. Here we present a method that accurately quantifies cytoskeleton dynamics. Our approach digitally subdivides cytoskeleton images using interrogation windows, within which box-counting is used to infer a fractal dimension (Df ) to characterize spatial arrangement, and gray value intensity (GVI) to determine actin density. A partitioning algorithm further obtains cytoskeleton characteristics from the perinuclear, cytosolic, and periphery cellular regions. We validated our measurement approach on Cytochalasin-treated cells using transgenically modified dermal fibroblast cells expressing fluorescent actin cytoskeletons. This method differentiates between normal and chemically disrupted actin networks, and quantifies rates of cytoskeletal degradation. Furthermore, GVI distributions were found to be inversely proportional to Df , having several biophysical implications for cytoskeleton formation/degradation. We additionally demonstrated detection sensitivity of differences in Df and GVI for cells seeded on substrates with varying degrees of stiffness, and coated with different attachment proteins. This general approach can be further implemented to gain insights on dynamic growth, disruption, and structure of the cytoskeleton (and other complex biological morphology) due to biological, chemical, or physical stimuli. © 2016 Wiley Periodicals, Inc. PMID:27015595

  16. Cytoskeleton and Early Development in Fucoid Algae

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Cell polarization and asymmetric cell divisions play important roles during development in many multicellular eukaryotes.Fucoid algae have a long history as models for studying early developmental processes, probably because of the ease with which zygotes can be observed and manipulated in the laboratory. This review discusses cell polarization and asymmetric cell divisions in fucoid algal zygotes with an emphasis on the roles played by the cytoskeleton.

  17. Cascade Organic Solar Cells

    KAUST Repository

    Schlenker, Cody W.

    2011-09-27

    We demonstrate planar organic solar cells consisting of a series of complementary donor materials with cascading exciton energies, incorporated in the following structure: glass/indium-tin-oxide/donor cascade/C 60/bathocuproine/Al. Using a tetracene layer grown in a descending energy cascade on 5,6-diphenyl-tetracene and capped with 5,6,11,12-tetraphenyl- tetracene, where the accessibility of the π-system in each material is expected to influence the rate of parasitic carrier leakage and charge recombination at the donor/acceptor interface, we observe an increase in open circuit voltage (Voc) of approximately 40% (corresponding to a change of +200 mV) compared to that of a single tetracene donor. Little change is observed in other parameters such as fill factor and short circuit current density (FF = 0.50 ± 0.02 and Jsc = 2.55 ± 0.23 mA/cm2) compared to those of the control tetracene-C60 solar cells (FF = 0.54 ± 0.02 and Jsc = 2.86 ± 0.23 mA/cm2). We demonstrate that this cascade architecture is effective in reducing losses due to polaron pair recombination at donor-acceptor interfaces, while enhancing spectral coverage, resulting in a substantial increase in the power conversion efficiency for cascade organic photovoltaic cells compared to tetracene and pentacene based devices with a single donor layer. © 2011 American Chemical Society.

  18. The role of the cytoskeleton in cellular force generation in 2D and 3D environments

    International Nuclear Information System (INIS)

    To adhere and migrate, cells generate forces through the cytoskeleton that are transmitted to the surrounding matrix. While cellular force generation has been studied on 2D substrates, less is known about cytoskeletal-mediated traction forces of cells embedded in more in vivo-like 3D matrices. Recent studies have revealed important differences between the cytoskeletal structure, adhesion, and migration of cells in 2D and 3D. Because the cytoskeleton mediates force, we sought to directly compare the role of the cytoskeleton in modulating cell force in 2D and 3D. MDA-MB-231 cells were treated with agents that perturbed actin, microtubules, or myosin, and analyzed for changes in cytoskeletal organization and force generation in both 2D and 3D. To quantify traction stresses in 2D, traction force microscopy was used; in 3D, force was assessed based on single cell-mediated collagen fibril reorganization imaged using confocal reflectance microscopy. Interestingly, even though previous studies have observed differences in cell behaviors like migration in 2D and 3D, our data indicate that forces generated on 2D substrates correlate with forces within 3D matrices. Disruption of actin, myosin or microtubules in either 2D or 3D microenvironments disrupts cell-generated force. These data suggest that despite differences in cytoskeletal organization in 2D and 3D, actin, microtubules and myosin contribute to contractility and matrix reorganization similarly in both microenvironments

  19. The role of the cytoskeleton in cellular force generation in 2D and 3D environments

    Science.gov (United States)

    Kraning-Rush, Casey M.; Carey, Shawn P.; Califano, Joseph P.; Smith, Brooke N.; Reinhart-King, Cynthia A.

    2011-02-01

    To adhere and migrate, cells generate forces through the cytoskeleton that are transmitted to the surrounding matrix. While cellular force generation has been studied on 2D substrates, less is known about cytoskeletal-mediated traction forces of cells embedded in more in vivo-like 3D matrices. Recent studies have revealed important differences between the cytoskeletal structure, adhesion, and migration of cells in 2D and 3D. Because the cytoskeleton mediates force, we sought to directly compare the role of the cytoskeleton in modulating cell force in 2D and 3D. MDA-MB-231 cells were treated with agents that perturbed actin, microtubules, or myosin, and analyzed for changes in cytoskeletal organization and force generation in both 2D and 3D. To quantify traction stresses in 2D, traction force microscopy was used; in 3D, force was assessed based on single cell-mediated collagen fibril reorganization imaged using confocal reflectance microscopy. Interestingly, even though previous studies have observed differences in cell behaviors like migration in 2D and 3D, our data indicate that forces generated on 2D substrates correlate with forces within 3D matrices. Disruption of actin, myosin or microtubules in either 2D or 3D microenvironments disrupts cell-generated force. These data suggest that despite differences in cytoskeletal organization in 2D and 3D, actin, microtubules and myosin contribute to contractility and matrix reorganization similarly in both microenvironments.

  20. Dispersion relations of cytoskeleton dynamics

    Directory of Open Access Journals (Sweden)

    Wang R

    2016-01-01

    Full Text Available Ru Wang,1,2 Lei Lei,3 Shamira Sridharan,1,3 Yingxiao Wang,3 Alex J Levine,4,5 Gabriel Popescu,1,3,6 1Quantitative Light Imaging Laboratory, Beckman Institute for Advanced Science and Technology, 2Department of Mechanical Science and Engineering, 3Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL, 4Department of Chemistry and Biochemistry, 5Department of Physics and Astronomy, University of California, Los Angeles, CA, 6Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA Abstract: While it is well known that the cytoskeleton plays a fundamental role in maintaining cell shape, performing cell division, and intracellular transport, its spatiotemporal dynamics are insufficiently understood. The dispersion relation, which is fundamental for understanding the connection between spatial and temporal scales of a dynamic system, was employed here for the first time to study the activity of actin and microtubules. Using green fluorescence protein for time-lapse imaging of the cytoskeleton, we showed that the dispersion relation can distinguish between diffusive and active transport of actin and microtubule filaments. Our analysis revealed that along the filaments, the transport was deterministic, as one might expect as the result of the active polymerization process, while across the filaments diffusion was dominant. Furthermore, using drugs to block the polymerization–depolymerization of both actin and microtubules, we measured that the transport immediately became diffusive, as expected. However, unexpectedly, our results indicated that within a few minutes from blocking its polymerization, actin recovered an active transport component. This deterministic component vanished upon treatment with nocodazole, indicating that fragments of actin were actively transported along microtubules. Because it provides information over broad temporal and spatial scales

  1. Cytoskeleton as an Emerging Target of Anthrax Toxins

    Directory of Open Access Journals (Sweden)

    Jean-Nicolas Tournier

    2012-02-01

    Full Text Available Bacillus anthracis, the agent of anthrax, has gained virulence through its exotoxins produced by vegetative bacilli and is composed of three components forming lethal toxin (LT and edema toxin (ET. So far, little is known about the effects of these toxins on the eukaryotic cytoskeleton. Here, we provide an overview on the general effects of toxin upon the cytoskeleton architecture. Thus, we shall discuss how anthrax toxins interact with their receptors and may disrupt the interface between extracellular matrix and the cytoskeleton. We then analyze what toxin molecular effects on cytoskeleton have been described, before discussing how the cytoskeleton may help the pathogen to corrupt general cell processes such as phagocytosis or vascular integrity.

  2. Subcortical cytoskeleton periodicity throughout the nervous system.

    Science.gov (United States)

    D'Este, Elisa; Kamin, Dirk; Velte, Caroline; Göttfert, Fabian; Simons, Mikael; Hell, Stefan W

    2016-01-01

    Superresolution fluorescence microscopy recently revealed a ~190 nm periodic cytoskeleton lattice consisting of actin, spectrin, and other proteins underneath the membrane of cultured hippocampal neurons. Whether the periodic cytoskeleton lattice is a structural feature of all neurons and how it is modified when axons are ensheathed by myelin forming glial cells is not known. Here, STED nanoscopy is used to demonstrate that this structure is a commonplace of virtually all neuron types in vitro. To check how the subcortical meshwork is modified during myelination, we studied sciatic nerve fibers from adult mice. Periodicity of both actin and spectrin was uncovered at the internodes, indicating no substantial differences between unmyelinated and myelinated axons. Remarkably, the actin/spectrin pattern was also detected in glial cells such as cultured oligodendrocyte precursor cells. Altogether our work shows that the periodic subcortical cytoskeletal meshwork is a fundamental characteristic of cells in the nervous system and is not a distinctive feature of neurons, as previously thought. PMID:26947559

  3. Harmonizing HeLa cell cytoskeleton behavior by multi-Ti oxide phased nanostructure synthesized through ultrashort pulsed laser

    Science.gov (United States)

    Chinnakkannu Vijayakumar, Chandramouli; Venkatakrishnan, Krishnan; Tan, Bo

    2015-10-01

    Knowledge about cancer cell behavior on heterogeneous nanostructures is relevant for developing a distinct biomaterial that can actuate cancer cells. In this manuscript, we have demonstrated a harmonized approach of forming multi Ti-oxide phases in a nanostructure (MTOP nanostructure) for its unique cancer cell controlling behavior.Conventionally, single phases of TiO2 are used for targeted therapy and as drug carrier systems.In this research, we have shown a biomaterial that can control HeLa cells diligently using a combination of TiO, Ti3O and TiO2 phases when compared to fibroblast (NIH3T3) cells.MTOP-nanostructures are generated by varying the ionization energy in the vapor plume of the ultrashort pulse laser; this interaction with the material allows accurate tuning and composition of phases within the nanostructure. In addition, the lattice spacing of MTOP-nanostructures was analyzed as shown by HR-TEM investigations. An FESEM investigation of MTOP-nanostructures revealed a greater reduction of HeLa cells relative to fibroblast cells. Altered cell adhesion was followed by modulation of HeLa cell architecture with a significant reduction of actin stress fibers.The intricate combination of MTOP-nanostructures renders a biomaterial that can precisely alter HeLa cell but not fibroblast cell behavior, filling a void in the research for a biomaterial to modulate cancer cell behavior.

  4. MAPK uncouples cell cycle progression from cell spreading and cytoskeletal organization in cycling cells

    OpenAIRE

    Margadant, Coert; Cremers, Lobke; Sonnenberg, Arnoud; Boonstra, Johannes

    2012-01-01

    Integrin-mediated cytoskeletal tension supports growth-factor-induced proliferation, and disruption of the actin cytoskeleton in growth factor-stimulated cells prevents the re-expression of cyclin D and cell cycle re-entry from quiescence. In contrast to cells that enter the cell cycle from G0, cycling cells continuously express cyclin D, and are subject to major cell shape changes during the cell cycle. Here, we investigated the cell cycle requirements for cytoskeletal tension and cell sprea...

  5. Nanostructures for Organic Solar Cells

    DEFF Research Database (Denmark)

    Goszczak, Arkadiusz Jarosław

    2016-01-01

    The experimental work in this thesis is focused on the fabrication of nanostructures that can be implemented in organic solar cell (OSC) architecture for enhancement of the device performance. Solar devices made from organic material are gaining increased attention, compared to their inorganic...... for organic solar cell applications, opening new patterning possibilities....

  6. Fluorescence staining of the actin cytoskeleton in living cells with 7-nitrobenz-2-oxa-1,3-diazole-phallacidin.

    OpenAIRE

    Barak, L S; Yocum, R R; Nothnagel, E A; Webb, W W

    1980-01-01

    An active fluorescent derivative of the actin-binding mushroom toxin phallacidin has been synthesized. Convenient methods were developed to stain actin cytoskeletal structures in living and fixed cultured animal cells and actively streaming algal cells. Actin binding specificity was demonstrated by competitive binding experiments and comparative staining of well-known structures. Large populations of living animal cells in culture were readily stained by using a relatively mild lysolecithin p...

  7. Effects of an antimitotic drug on mechanical behaviours of the cytoskeleton in distinct grades of colon cancer cells.

    Science.gov (United States)

    Seyedpour, S M; Pachenari, M; Janmaleki, M; Alizadeh, M; Hosseinkhani, H

    2015-04-13

    Biomechanical behaviours of cells change during cancer progression due to alterations in the main cytoskeletal proteins. Microtubules play a vital role in mitosis and in supporting the integrity of the cell due to their ability to withstand high compressive loads. Accordingly, microtubule-targeting agents (MTAs) have become one of the most promising classes of drugs in cancer therapy. This study evaluated changes in visco-elastic parameters induced by an appropriate concentration of an antimitotic drug in two different grades of colon cancer cells. Actin microfilaments and microtubules contents in the cells were evaluated by Western blot analysis and fluorescence intensity calculation. Micropipette aspiration experiments showed that the MTA had distinct mechanical effects on different cell lines. The more aggressive the cells, the greater the reduction in elasticity and viscosity. Invasive cells had a higher initial instantaneous Young's modulus than primary cells, but this reduced to approximately one half of the values for primary cells after 48 h of drug treatment. A considerable association was seen between the changes in mechanical properties and the microtubule to F-actin microfilament content ratio, which decreased with MTA treatment. PMID:25678199

  8. Components of the cytoskeleton in the retinal pigmented epithelium of the chick

    OpenAIRE

    1985-01-01

    The retinal pigmented epithelium (RPE) is a simple cuboidal epithelium with apical processes which, unlike many epithelia, do not extend freely into a lumen but rather interdigitate closely with the outer segments of the neural retina. To determine whether this close association was reflected in the cytoskeletal organization of the RPE, we studied the components of the cytoskeleton of the RPE and their localization in the body of the cell and in the apical processes. By relative mobility on S...

  9. Yersinia outer proteins E, H, P, and T differentially target the cytoskeleton and inhibit phagocytic capacity of dendritic cells

    Czech Academy of Sciences Publication Activity Database

    Adkins, Irena; Köberle, M.; Gröbner, S.; Bohn, E.; Autenrieth, I. B.; Borgmann, S.

    2007-01-01

    Roč. 297, - (2007), s. 235-244. ISSN 1438-4221 Institutional research plan: CEZ:AV0Z50200510 Keywords : yersinia * yops * dendritic cells Subject RIV: EC - Immunology Impact factor: 2.524, year: 2007

  10. Differential Gene Regulation under Altered Gravity Conditions in Follicular Thyroid Cancer Cells: Relationship between the Extracellular Matrix and the Cytoskeleton

    OpenAIRE

    Ulbrich, Claudia; Pietsch, Jessica; Grosse, Jirka; Wehland, Markus; Schulz, Herbert; Saar, Katrin; Hübner, Norbert; Hauslage, Jens; Hemmersbach, Ruth; Braun, Markus; van Loon, Jack; Vagt, Nicole; EGLI, Marcel; Richter, Peter; Einspanier, Ralf

    2013-01-01

    Extracellular matrix proteins, adhesion molecules, and cytoskeletal proteins form a dynamic network interacting with signalling molecules as an adaptive response to altered gravity. An important issue is the exact differentiation between real microgravity responses of the cells or cellular reactions to hypergravity and/or vibrations. To determine the effects of real microgravity on human cells, we used four DLR parabolic flight campaigns and focused on the effects of short-term microgravity (...

  11. Probing the effect of elevated cholesterol on the mechanical properties of membrane-cytoskeleton by optical tweezers

    Science.gov (United States)

    Rajkumar, Arun S.; Muley, Ajit; Chatterjee, Suvro; Jaffar Ali, B. M.

    2010-08-01

    The composition of the cell membrane and the surrounding physiological factors determine the nature and dynamics of membrane-cytoskeleton coupling. Mechanical strength of a cell is mainly derived from such coupling. In this article, we investigate the effect of extra cellular cholesterol on the membrane-cytoskelaton connectivity of single cell endothelium and consequent remodeling of its mechanical properties. Using optical tweezers as a force probe, we have measured membrane stiffness (km), membrane microviscosity (ηeff ) and the two-dimensional shear modulus (G'(f)) as a function of extracellular cholesterol in the range of 0.1mM to 6mM. We find that membrane stiffness and shear modulus are dependent on cholesterol-induced membrane-cytoskeletal organization. Further, by disrupting the membranecytoskeletal connectivity with Cytochalasin D, an actin delpolymerizing molecule, we recover pure membrane behaviour devoid of any cytoskeleton attachment. However, behaviour of ηeff was found to be unaffected by disruption of membrane-cytoskeleton organization. We infer that cholesterol is playing a distinct role in modulating membrane organization and membrane-cytoskeleton connectivity independently. We further discuss implications of our approach in characterizing cellular mechanics.

  12. Reciprocal regulation of actin cytoskeleton remodelling and cell migration by Ca2+ and Zn2+: role of TRPM2 channels.

    Science.gov (United States)

    Li, Fangfang; Abuarab, Nada; Sivaprasadarao, Asipu

    2016-05-15

    Cell migration is a fundamental feature of tumour metastasis and angiogenesis. It is regulated by a variety of signalling molecules including H2O2 and Ca(2+) Here, we asked whether the H2O2-sensitive transient receptor potential melastatin 2 (TRPM2) Ca(2+) channel serves as a molecular link between H2O2 and Ca(2+) H2O2-mediated activation of TRPM2 channels induced filopodia formation, loss of actin stress fibres and disassembly of focal adhesions, leading to increased migration of HeLa and prostate cancer (PC)-3 cells. Activation of TRPM2 channels, however, caused intracellular release of not only Ca(2+) but also of Zn(2+) Intriguingly, elevation of intracellular Zn(2+) faithfully reproduced all of the effects of H2O2, whereas Ca(2+) showed opposite effects. Interestingly, H2O2 caused increased trafficking of Zn(2+)-enriched lysosomes to the leading edge of migrating cells, presumably to impart polarisation of Zn(2+) location. Thus, our results indicate that a reciprocal interplay between Ca(2+) and Zn(2+) regulates actin remodelling and cell migration; they call for a revision of the current notion that implicates an exclusive role for Ca(2+) in cell migration. PMID:27068538

  13. Mechanics of membrane-cytoskeleton attachment in Paramecium

    Science.gov (United States)

    Campillo, C.; Jerber, J.; Fisch, C.; Simoes-Betbeder, M.; Dupuis-Williams, P.; Nassoy, P.; Sykes, C.

    2012-12-01

    In this paper we assess the role of the protein MKS1 (Meckel syndrome type 1) in the cortical membrane mechanics of the ciliated protist Paramecium. This protein is known to be crucial in the process of cilium formation, and we investigate its putative role in membrane-cytoskeleton attachment. Therefore, we compare cells where the gene coding for MKS1 is silenced to wild-type cells. We found that scanning electron microscopy observation of the cell surface reveals a cup-like structure in wild-type cells that is lost in silenced cells. Since this structure is based on the underlying cytoskeleton, one hypothesis to explain this observation is a disruption of membrane attachment to the cytoskeleton in the absence of MKS1 that should affect plasma membrane mechanics. We test this by probing the mechanics of wild-type and silenced cells by micropipette aspiration. Strikingly, we observe that, at the same aspiration pressure, the membrane of silenced cells is easily aspirated by the micropipette whereas that of wild-type cells enters only at a moderate velocity, an effect that suggests a detachment of the membrane from the underlying cytoskeleton in silenced cells. We quantify this detachment by measuring the deformation of the cell cortex and the rate of cell membrane entry in the micropipette. This study offers a new perspective for the characterization of membrane-cytoskeleton attachment in protists and paves the way for a better understanding of the role of membrane-cortex attachment in cilium formation.

  14. Mechanics of membrane–cytoskeleton attachment in Paramecium

    International Nuclear Information System (INIS)

    In this paper we assess the role of the protein MKS1 (Meckel syndrome type 1) in the cortical membrane mechanics of the ciliated protist Paramecium. This protein is known to be crucial in the process of cilium formation, and we investigate its putative role in membrane–cytoskeleton attachment. Therefore, we compare cells where the gene coding for MKS1 is silenced to wild-type cells. We found that scanning electron microscopy observation of the cell surface reveals a cup-like structure in wild-type cells that is lost in silenced cells. Since this structure is based on the underlying cytoskeleton, one hypothesis to explain this observation is a disruption of membrane attachment to the cytoskeleton in the absence of MKS1 that should affect plasma membrane mechanics. We test this by probing the mechanics of wild-type and silenced cells by micropipette aspiration. Strikingly, we observe that, at the same aspiration pressure, the membrane of silenced cells is easily aspirated by the micropipette whereas that of wild-type cells enters only at a moderate velocity, an effect that suggests a detachment of the membrane from the underlying cytoskeleton in silenced cells. We quantify this detachment by measuring the deformation of the cell cortex and the rate of cell membrane entry in the micropipette. This study offers a new perspective for the characterization of membrane–cytoskeleton attachment in protists and paves the way for a better understanding of the role of membrane–cortex attachment in cilium formation. (paper)

  15. Apical Invasion of Intestinal Epithelial Cells by Salmonella typhimurium Requires Villin to Remodel the Brush Border Actin Cytoskeleton

    OpenAIRE

    Lhocine, Nouara; Arena, Ellen T.; Bomme, Perrine; Ubelmann, Florent; Prévost, Marie-Christine; Robine, Sylvie; Sansonetti, Philippe J.

    2015-01-01

    Summary Salmonella invasion of intestinal epithelial cells requires extensive, though transient, actin modifications at the site of bacterial entry. The actin-modifying protein villin is present in the brush border where it participates in the constitution of microvilli and in epithelial restitution after damage through its actin-severing activity. We investigated a possible role for villin in Salmonella invasion. The absence of villin, which is normally located at the bacterial entry site, l...

  16. Proteomic analysis of the action of the Mycobacterium ulcerans toxin mycolactone: targeting host cells cytoskeleton and collagen.

    OpenAIRE

    Gama, José B.; Steffen Ohlmeier; Martins, Teresa G.; Fraga, Alexandra G.; Belém Sampaio-Marques; Carvalho, Maria A.; Fernanda Proença; Silva, Manuel T.; Jorge Pedrosa; Paula Ludovico

    2014-01-01

    Buruli ulcer (BU) is a neglected tropical disease caused by Mycobacterium ulcerans. The tissue damage characteristic of BU lesions is known to be driven by the secretion of the potent lipidic exotoxin mycolactone. However, the molecular action of mycolactone on host cell biology mediating cytopathogenesis is not fully understood. Here we applied two-dimensional electrophoresis (2-DE) to identify the mechanisms of mycolactone's cellular action in the L929 mouse fibroblast proteome. This reveal...

  17. Proteomic Analysis of the Action of the Mycobacterium ulcerans Toxin Mycolactone: Targeting Host Cells Cytoskeleton and Collagen

    OpenAIRE

    Gama, José B.; Ohlmeier, S.; Martins, Teresa G.; Fraga, Alexandra G.; Marques, Belém Sampaio; Carvalho, M. Alice; Proença, M. Fernanda R. P.; Silva, Manuel T.; Pedrosa, Jorge; Ludovico, Paula

    2014-01-01

    Buruli ulcer (BU) is a neglected tropical disease caused by Mycobacterium ulcerans. The tissue damage characteristic of BU lesions is known to be driven by the secretion of the potent lipidic exotoxin mycolactone. However, the molecular action of mycolactone on host cell biology mediating cytopathogenesis is not fully understood. Here we applied two-dimensional electrophoresis (2-DE) to identify the mechanisms of mycolactone's cellular action in the L929 mouse fibroblast proteome. This reveal...

  18. Quantitative phospho-proteomics reveals the Plasmodium merozoite triggers pre-invasion host kinase modification of the red cell cytoskeleton.

    Science.gov (United States)

    Zuccala, Elizabeth S; Satchwell, Timothy J; Angrisano, Fiona; Tan, Yan Hong; Wilson, Marieangela C; Heesom, Kate J; Baum, Jake

    2016-01-01

    The invasive blood-stage malaria parasite - the merozoite - induces rapid morphological changes to the target erythrocyte during entry. However, evidence for active molecular changes in the host cell that accompany merozoite invasion is lacking. Here, we use invasion inhibition assays, erythrocyte resealing and high-definition imaging to explore red cell responses during invasion. We show that although merozoite entry does not involve erythrocyte actin reorganisation, it does require ATP to complete the process. Towards dissecting the ATP requirement, we present an in depth quantitative phospho-proteomic analysis of the erythrocyte during each stage of invasion. Specifically, we demonstrate extensive increased phosphorylation of erythrocyte proteins on merozoite attachment, including modification of the cytoskeletal proteins beta-spectrin and PIEZO1. The association with merozoite contact but not active entry demonstrates that parasite-dependent phosphorylation is mediated by host-cell kinase activity. This provides the first evidence that the erythrocyte is stimulated to respond to early invasion events through molecular changes in its membrane architecture. PMID:26830761

  19. The cytoskeleton as a novel therapeutic target for old neurodegenerative disorders.

    Science.gov (United States)

    Eira, Jessica; Silva, Catarina Santos; Sousa, Mónica Mendes; Liz, Márcia Almeida

    2016-06-01

    Cytoskeleton defects, including alterations in microtubule stability, in axonal transport as well as in actin dynamics, have been characterized in several unrelated neurodegenerative conditions. These observations suggest that defects of cytoskeleton organization may be a common feature contributing to neurodegeneration. In line with this hypothesis, drugs targeting the cytoskeleton are currently being tested in animal models and in human clinical trials, showing promising effects. Drugs that modulate microtubule stability, inhibitors of posttranslational modifications of cytoskeletal components, specifically compounds affecting the levels of tubulin acetylation, and compounds targeting signaling molecules which regulate cytoskeleton dynamics, constitute the mostly addressed therapeutic interventions aiming at preventing cytoskeleton damage in neurodegenerative disorders. In this review, we will discuss in a critical perspective the current knowledge on cytoskeleton damage pathways as well as therapeutic strategies designed to revert cytoskeleton-related defects mainly focusing on the following neurodegenerative disorders: Alzheimer's Disease, Parkinson's Disease, Huntington's Disease, Amyotrophic Lateral Sclerosis and Charcot-Marie-Tooth Disease. PMID:27095262

  20. Stem cell organization in Arabidopsis

    OpenAIRE

    Wendrich, J.R.

    2016-01-01

    Growth of plant tissues and organs depends on continuous production of new cells, by niches of stem cells. Stem cells typically divide to give rise to one differentiating daughter and one non-differentiating daughter. This constant process of self-renewal ensures that the niches of stem cells or meristems stay active throughout plant-life. Specification of stem cells occurs very early during development of the emrbyo and they are maintained during later stages. The Arabidopsis embryo is a hig...

  1. Rho proteins − the key regulators of cytoskeleton in the progression of mitosis and cytokinesis

    Directory of Open Access Journals (Sweden)

    Anna Klimaszewska

    2011-11-01

    Full Text Available The Rho proteins are members of the Ras superfamily of small GTPases. They are thought to be crucial regulators of multiple signal transduction pathways that influence a wide range of cellular functions, including migration, membrane trafficking, adhesion, polarity and cell shape changes. Thanks to their ability to control the assembly and organization of the actin and microtubule cytoskeletons, Rho GTPases are known to regulate mitosis and cytokinesis progression. These proteins are required for formation and rigidity of the cortex during mitotic cell rounding, mitotic spindle formation and attachment of the spindle microtubules to the kinetochore. In addition, during cytokinesis, they are involved in promoting division plane determination, contractile ring and cleavage furrow formation and abscission. They are also known as regulators of cell cycle progression at the G1/S and G2/M transition. Thus, the signal transduction pathways in which Rho proteins participate, appear to connect dynamics of actin and microtubule cytoskeletons to cell cycle progression. We review the current state of knowledge concerning the molecular mechanisms by which Rho GTPase signaling regulates remodeling of actin and microtubule cytoskeletons in order to control cell division progression.

  2. Actin Cytoskeleton Contributes to the Elastic Modulus of Embryonic Tendon During Early Development

    Science.gov (United States)

    Schiele, Nathan R.; von Flotow, Friedrich; Tochka, Zachary L.; Hockaday, Laura A.; Marturano, Joseph E.; Thibodeau, Jeffrey J.; Kuo, Catherine K.

    2016-01-01

    Tendon injuries are common and heal poorly. Strategies to regenerate or replace injured tendons are challenged by an incomplete understanding of normal tendon development. Our previous study showed that embryonic tendon elastic modulus increases as a function of developmental stage. Inhibition of enzymatic collagen crosslink formation abrogated increases in tendon elastic modulus at late developmental stages, but did not affect increases in elastic modulus of early stage embryonic tendons. Here, we aimed to identify potential contributors to the mechanical properties of these early stage embryonic tendons. We characterized tendon progenitor cells in early stage embryonic tendons, and the influence of actin cytoskeleton disruption on tissue elastic modulus. Cells were closely packed in embryonic tendons, and did not change in density during early development. We observed an organized network of actin filaments that seemed contiguous between adjacent cells. The actin filaments exhibited a crimp pattern with a period and amplitude that matched the crimp of collagen fibers at each developmental stage. Chemical disruption of the actin cytoskeleton decreased tendon tissue elastic modulus, measured by atomic force microscopy. Our results demonstrate that early developmental stage embryonic tendons possess a well organized actin cytoskeleton network that contributes significantly to tendon tissue mechanical properties. PMID:25721681

  3. Hypothyroidism decreases proinsulin gene expression and the attachment of its mRNA and eEF1A protein to the actin cytoskeleton of INS-1E cells

    OpenAIRE

    Goulart-Silva, F.; C. Serrano-Nascimento; Nunes, M.T.

    2011-01-01

    The actions of thyroid hormone (TH) on pancreatic beta cells have not been thoroughly explored, with current knowledge being limited to the modulation of insulin secretion in response to glucose, and beta cell viability by regulation of pro-mitotic and pro-apoptotic factors. Therefore, the effects of TH on proinsulin gene expression are not known. This led us to measure: a) proinsulin mRNA expression, b) proinsulin transcripts and eEF1A protein binding to the actin cytoskeleton, c) actin cyto...

  4. Effects of oriented substrates on cell morphology,the cell cycle,and the cytoskeleton in Ros 17/2.8 cells

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Absence of gravity or microgravity influences the cellular functions of bone forming osteoblasts.The underlying mechanism,however,of cellular sensing and responding to the gravity vector is poorly understood.This work quantified the impact of vector-directional gravity on the biological responses of Ros 17/2.8 cells grown on upward-,downward-or edge-on-oriented substrates.Cell morphology and nuclear translocation,cell proliferation and the cell cycle,and cytoskeletal reorganization were found to vary significantly in the three orientations.All of the responses were duration-dependent.These results provide a new insight into understanding how osteoblasts respond to static vector-directional gravity.

  5. Regulation of actin cytoskeleton architecture by Eps8 and Abi1

    Directory of Open Access Journals (Sweden)

    Miller Jeffrey R

    2005-10-01

    Full Text Available Abstract Background The actin cytoskeleton participates in many fundamental processes including the regulation of cell shape, motility, and adhesion. The remodeling of the actin cytoskeleton is dependent on actin binding proteins, which organize actin filaments into specific structures that allow them to perform various specialized functions. The Eps8 family of proteins is implicated in the regulation of actin cytoskeleton remodeling during cell migration, yet the precise mechanism by which Eps8 regulates actin organization and remodeling remains elusive. Results Here, we show that Eps8 promotes the assembly of actin rich filopodia-like structures and actin cables in cultured mammalian cells and Xenopus embryos, respectively. The morphology of actin structures induced by Eps8 was modulated by interactions with Abi1, which stimulated formation of actin cables in cultured cells and star-like structures in Xenopus. The actin stars observed in Xenopus animal cap cells assembled at the apical surface of epithelial cells in a Rac-independent manner and their formation was accompanied by recruitment of N-WASP, suggesting that the Eps8/Abi1 complex is capable of regulating the localization and/or activity of actin nucleators. We also found that Eps8 recruits Dishevelled to the plasma membrane and actin filaments suggesting that Eps8 might participate in non-canonical Wnt/Polarity signaling. Consistent with this idea, mis-expression of Eps8 in dorsal regions of Xenopus embryos resulted in gastrulation defects. Conclusion Together, these results suggest that Eps8 plays multiple roles in modulating actin filament organization, possibly through its interaction with distinct sets of actin regulatory complexes. Furthermore, the finding that Eps8 interacts with Dsh and induced gastrulation defects provides evidence that Eps8 might participate in non-canonical Wnt signaling to control cell movements during vertebrate development.

  6. Inverted organic photovoltaic cells.

    Science.gov (United States)

    Wang, Kai; Liu, Chang; Meng, Tianyu; Yi, Chao; Gong, Xiong

    2016-05-21

    The advance in lifestyle, modern industrialization and future technological revolution are always at high expense of energy consumption. Unfortunately, there exist serious issues such as limited storage, high cost and toxic contamination in conventional fossil fuel energy sources. Instead, solar energy represents a renewable, economic and green alternative in the future energy market. Among the photovoltaic technologies, organic photovoltaics (OPVs) demonstrate a cheap, flexible, clean and easy-processing way to convert solar energy into electricity. However, OPVs with a conventional device structure are still far away from industrialization mainly because of their short lifetime and the energy-intensive deposition of top metal electrode. To address the stability and cost issue simultaneously, an inverted device structure has been introduced into OPVs, bridging laboratory research with practical application. In this review, recent progress in device structures, working mechanisms, functions and advances of each component layer as well their correlations with the efficiency and stability of inverted OPVs are reviewed and illustrated. PMID:27087582

  7. Severe disruption of the cytoskeleton and immunologically relevant surface molecules in a human macrophageal cell line in microgravity-Results of an in vitro experiment on board of the Shenzhou-8 space mission

    Science.gov (United States)

    Paulsen, Katrin; Tauber, Svantje; Goelz, Nadine; Simmet, Dana Michaela; Engeli, Stephanie; Birlem, Maria; Dumrese, Claudia; Karer, Anissja; Hunziker, Sandra; Biskup, Josefine; Konopasek, Shalimar; Suh, Durie; Hürlimann, Eva; Signer, Christoph; Wang, Anna; Sang, Chen; Grote, Karl-Heinrich; Zhuang, Fengyuan; Ullrich, Oliver

    2014-01-01

    During spaceflight the immune system is one of the most affected systems of the human body. During the SIMBOX (Science in Microgravity Box) mission on Shenzhou-8, we investigated microgravity-associated long-term alterations in macrophageal cells, the most important effector cells of the immune system. We analyzed the effect of long-term microgravity on the cytoskeleton and immunologically relevant surface molecules. Human U937 cells were differentiated into a macrophageal phenotype and exposed to microgravity or 1g on a reference centrifuge on-orbit for 5 days. After on-orbit fixation, the samples were analyzed with immunocytochemical staining and confocal microscopy after landing. The unmanned Shenzhou-8 spacecraft was launched on board a Long March 2F (CZ-2F) rocket from the Jiuquan Satellite Launch Center (JSLC) and landed after a 17-day-mission. We found a severely disturbed actin cytoskeleton, disorganized tubulin and distinctly reduced expression of CD18, CD36 and MHC-II after the 5 days in microgravity. The disturbed cytoskeleton, the loss of surface receptors for bacteria recognition, the activation of T lymphocytes, the loss of an important scavenger receptor and of antigen-presenting molecules could represent a dysfunctional macrophage phenotype. This phenotype in microgravity would be not capable of migrating or recognizing and attacking pathogens, and it would no longer activate the specific immune system, which could be investigated in functional assays. Obviously, the results have to be interpreted with caution as the model system has some limitations and due to numerous technical and biological restrictions (e.g. 23 °C and no CO2 supply during in-flight incubation). All parameter were carefully pre-tested on ground. Therefore, the experiment could be adapted to the experimental conditions available on Shenzhou-8.

  8. Estrogen mediated protection of cytoskeleton against oxidative stress

    Directory of Open Access Journals (Sweden)

    Darshini A Ganatra

    2013-01-01

    Interpretation & conclusions: Our findings showed that E 2 helped in preventing deteriorating effect of H 2 O 2 , inhibited cell death, apoptosis and depolymerisation of cytoskeletal proteins in LECs. However, the exact mechanism by which estrogen renders this protection to cytoskeleton of lens epithelial cells remains to be determined.

  9. Organic and hybrid solar cells

    CERN Document Server

    Huang, Hui

    2014-01-01

    This book delivers a comprehensive evaluation of organic and hybrid solar cells and identifies their fundamental principles and numerous applications. Great attention is given to the charge transport mechanism, donor and acceptor materials, interfacial materials, alternative electrodes, device engineering and physics, and device stability. The authors provide an industrial perspective on the future of photovoltaic technologies.

  10. Cytoskeleton dynamics: Fluctuations within the network

    International Nuclear Information System (INIS)

    Out-of-equilibrium systems, such as the dynamics of a living cytoskeleton (CSK), are inherently noisy with fluctuations arising from the stochastic nature of the underlying biochemical and molecular events. Recently, such fluctuations within the cell were characterized by observing spontaneous nano-scale motions of an RGD-coated microbead bound to the cell surface [Bursac et al., Nat. Mater. 4 (2005) 557-561]. While these reported anomalous bead motions represent a molecular level reorganization (remodeling) of microstructures in contact with the bead, a precise nature of these cytoskeletal constituents and forces that drive their remodeling dynamics are largely unclear. Here, we focused upon spontaneous motions of an RGD-coated bead and, in particular, assessed to what extent these motions are attributable to (i) bulk cell movement (cell crawling), (ii) dynamics of focal adhesions, (iii) dynamics of lipid membrane, and/or (iv) dynamics of the underlying actin CSK driven by myosin motors

  11. Foot-and-mouth disease virus, but not bovine enterovirus, targets the host cell cytoskeleton, via the non-structural protein 3Cpro

    DEFF Research Database (Denmark)

    Armer, Hannah; Moffat, Katy; Wileman, Thomas;

    2008-01-01

    Foot-and-mouth disease virus (FMDV), a member of the Picornaviridae, is a pathogen of cloven-hoofed animals and causes a disease of major economic importance. Picornavirus-infected cells show changes in cell morphology and rearrangement of cytoplasmic membranes, which are a consequence of virus...... replication. We show here, by confocal immunofluorescence and electron microscopy, that the changes in morphology of FMDV-infected cells involve changes in the distribution of microtubule and intermediate filament components during infection. Despite the continued presence of centrosomes in infected cells......, there is a loss of tethering of microtubules to the microtubule organizing center (MTOC) region. Loss of labeling for -tubulin, but not pericentrin, from the MTOC suggests a targeting of -tubulin (or associated proteins) rather than a total breakdown in MTOC structure. The identity of the FMDV protein...

  12. Enriched inorganic compounds in diesel exhaust particles induce mitogen-activated protein kinase activation, cytoskeleton instability, and cytotoxicity in human bronchial epithelial cells.

    Science.gov (United States)

    Seriani, Robson; Junqueira, Mara S; Carvalho-Sousa, Claudia E; Arruda, Alessandra C T; Martinez, Diana; Alencar, Adriano M; Garippo, Ana L; Brito, Jôse Mara; Martins, Milton A; Saldiva, Paulo H N; Negri, Elnara M; Mauad, Thais; Macchione, Mariangela

    2015-04-01

    This study assessed the effects of the diesel exhaust particles on ERK and JNK MAPKs activation, cell rheology (viscoelasticity), and cytotoxicity in bronchial epithelial airway cells (BEAS-2B). Crude DEP and DEP after extraction with hexane (DEP/HEX) were utilized. The partial reduction of some DEP/HEX organics increased the biodisponibility of many metallic elements. JNK and ERK were activated simultaneously by crude DEP with no alterations in viscoelasticity of the cells. Mitochondrial activity, however, revealed a decrease through the MTT assay. DEP/HEX treatment increased viscoelasticity and cytotoxicity (membrane damage), and also activated JNK. Our data suggest that the greater bioavailability of metals could be involved in JNK activation and, consequently, in the reduction of fiber coherence and increase in the viscoelasticity and cytotoxicity of BEAS cells. The adverse findings detected after exposure to crude DEP and to DEP/HEX reflect the toxic potential of diesel compounds. Considering the fact that the cells of the respiratory epithelium are the first line of defense between the body and the environment, our data contribute to a better understanding of the pathways leading to respiratory cell injury and provide evidence for the onset of or worsening of respiratory diseases caused by inorganic compounds present in DEP. PMID:25769681

  13. Curcumin inhibits cellular condensation and alters microfilament organization during chondrogenic differentiation of limb bud mesenchymal cells.

    Science.gov (United States)

    Kim, Dong Kyun; Kim, Song Ja; Kang, Shin Sung; Jin, Eun Jung

    2009-09-30

    Curcumin is a well known natural polyphenol product isolated from the rhizome of the plant Curcuma longa, anti-inflammatory agent for arthritis by inhibiting synthesis of inflammatory prostaglandins. However, the mechanisms by which curcumin regulates the functions of chondroprogenitor, such as proliferation, precartilage condensation, cytoskeletal organization or overall chondrogenic behavior, are largely unknown. In the present report, we investigated the effects and signaling mechanism of curcumin on the regulation of chondrogenesis. Treating chick limb bud mesenchymal cells with curcumin suppressed chondrogenesis by stimulating apoptotic cell death. It also inhibited reorganization of the actin cytoskeleton into a cortical pattern concomitant with rounding of chondrogenic competent cells and down-regulation of integrin beta1 and focal adhesion kinase (FAK) phosphorylation. Curcumin suppressed the phosphorylation of Akt leading to Akt inactivation. Activation of Akt by introducing a myristoylated, constitutively active form of Akt reversed the inhibitory actions of curcumin during chondrogenesis. In summary, for the first time, we describe biological properties of curcumin during chondrogenic differentiation of chick limb bud mesenchymal cells. Curcumin suppressed chondrogenesis by stimulating apoptotic cell death and down-regulating integrin-mediated reorganization of actin cytoskeleton via modulation of Akt signaling. PMID:19478554

  14. Neuronal migration disorders: Focus on the cytoskeleton and epilepsy.

    Science.gov (United States)

    Stouffer, Melissa A; Golden, Jeffrey A; Francis, Fiona

    2016-08-01

    A wide spectrum of focal, regional, or diffuse structural brain abnormalities, collectively known as malformations of cortical development (MCDs), frequently manifest with intellectual disability (ID), epilepsy, and/or autistic spectrum disorder (ASD). As the acronym suggests, MCDs are perturbations of the normal architecture of the cerebral cortex and hippocampus. The pathogenesis of these disorders remains incompletely understood; however, one area that has provided important insights has been the study of neuronal migration. The amalgamation of human genetics and experimental studies in animal models has led to the recognition that common genetic causes of neurodevelopmental disorders, including many severe epilepsy syndromes, are due to mutations in genes regulating the migration of newly born post-mitotic neurons. Neuronal migration genes often, though not exclusively, code for proteins involved in the function of the cytoskeleton. Other cellular processes, such as cell division and axon/dendrite formation, which similarly depend on cytoskeletal functions, may also be affected. We focus here on how the susceptibility of the highly organized neocortex and hippocampus may be due to their laminar organization, which involves the tight regulation, both temporally and spatially, of gene expression, specialized progenitor cells, the migration of neurons over large distances and a birthdate-specific layering of neurons. Perturbations in neuronal migration result in abnormal lamination, neuronal differentiation defects, abnormal cellular morphology and circuit formation. Ultimately this results in disorganized excitatory and inhibitory activity leading to the symptoms observed in individuals with these disorders. PMID:26299390

  15. Mechanics of membrane-cytoskeleton attachment in Paramecium

    OpenAIRE

    Campillo, Clément; Jerber, Julie; Fisch, Cathy; Simoes-Betbeder, Maria; Dupuis-Williams, Pascale; Nassoy, Pierre; Sykes, Cécile

    2012-01-01

    International audience In this paper we assess the role of the protein MKS1 (Meckel syndrome type 1) in the cortical membrane mechanics of the ciliated protist Paramecium. This protein is known to be crucial in the process of cilium formation, and we investigate its putative role in membrane-cytoskeleton attachment. Therefore, we compare cells where the gene coding for MKS1 is silenced to wild-type cells. We found that scanning electron microscopy observation of the cell surface reveals a ...

  16. Interfacial models of nerve fiber cytoskeleton.

    OpenAIRE

    Malev, V V; Gromov, D B; Komissarchik YaYu; Brudnaya, M S

    1992-01-01

    A new approach, basing on a resemblance between cytoskeleton structures associated with plasma membranes and interfacial layers of coexisting phases, is proposed. In particular, a lattice model, similar to those of the theory of surface properties of pure liquids and nonelectrolyte solutions (Ono, S., and S. Kondo. 1960. Handbuch der Physik.), has been developed to describe nerve fiber cytoskeleton. The preliminary consideration of the model shows the existence of submembrane cytoskeleton hav...

  17. The plant actin cytoskeleton responds to signals from microbe-associated molecular patterns.

    Directory of Open Access Journals (Sweden)

    Jessica L Henty-Ridilla

    Full Text Available Plants are constantly exposed to a large and diverse array of microbes; however, most plants are immune to the majority of potential invaders and susceptible to only a small subset of pathogens. The cytoskeleton comprises a dynamic intracellular framework that responds rapidly to biotic stresses and supports numerous fundamental cellular processes including vesicle trafficking, endocytosis and the spatial distribution of organelles and protein complexes. For years, the actin cytoskeleton has been assumed to play a role in plant innate immunity against fungi and oomycetes, based largely on static images and pharmacological studies. To date, however, there is little evidence that the host-cell actin cytoskeleton participates in responses to phytopathogenic bacteria. Here, we quantified the spatiotemporal changes in host-cell cytoskeletal architecture during the immune response to pathogenic and non-pathogenic strains of Pseudomonas syringae pv. tomato DC3000. Two distinct changes to host cytoskeletal arrays were observed that correspond to distinct phases of plant-bacterial interactions i.e. the perception of microbe-associated molecular patterns (MAMPs during pattern-triggered immunity (PTI and perturbations by effector proteins during effector-triggered susceptibility (ETS. We demonstrate that an immediate increase in actin filament abundance is a conserved and novel component of PTI. Notably, treatment of leaves with a MAMP peptide mimic was sufficient to elicit a rapid change in actin organization in epidermal cells, and this actin response required the host-cell MAMP receptor kinase complex, including FLS2, BAK1 and BIK1. Finally, we found that actin polymerization is necessary for the increase in actin filament density and that blocking this increase with the actin-disrupting drug latrunculin B leads to enhanced susceptibility of host plants to pathogenic and non-pathogenic bacteria.

  18. Nanostructured Inverted Organic Photovoltaic Cells

    Science.gov (United States)

    Thomas, Michael

    Organic photovoltaic cells (OPVs)are promising devices for inexpensive power generation from sunlight. Organic semiconductors, the basic materials for OPVs, can be fabricated using a broad range of fabrication technologies from vapor deposition to solution processing. Upon light absorption, a strongly bound exciton is generated which can diffuse to a donor-acceptor heterojunction. At this interface it can be dissociated into free charge carriers which can be collected by the device electrodes. A major challenge for OPVs are short exciton diffusion lengths of up to 20 nm. Morphology engineering is required in order to harvest the exciton before it recombines and improve OPV performance. This work focuses on the study of nanostructured morphologies for use in inverted architecture OPVs. Glancing angle deposition (GLAD)is employed to fabricate nanocolumnar acceptor films. Through combining these nanostructured C60 films with a conjugated polymer donor P3CBT and a small molecule 3-Q, inverted OPVs are fabricated with the goal to analyze effect of morphology engineering on device performance. A major challenge was that C60 were found to be soluble in most commonly used organic solvents such as dichlorobenzene or chloroform. Although this challenge has limited the donor choice and therefore has limited device performance, a significant effect of morphology engineering could be observed. All GLAD structured C60 OPVs outperformed state of the art architectures such as planar films and bulk heterojunctions fabricated with the same materials. For P3CBT in particular the GLAD structured devices exhibited a twofold increase in power conversion efficiency compared with bulk heterojunctions and a fourfold increase compared with planar devices. In a further study, the acceptor materials PTCDA and C60 were co-evaporated into a single film. PTCDA is stable against non-polar organic solvents while C60 provides a high electron mobility. Nanocolumnar acceptor blended PTCDA:C60 films

  19. Chaperonin Polymers in Archaea: The Cytoskeleton of Prokaryotes?

    Science.gov (United States)

    Trent, J. D.; Kagawa, H. K.; Zaluzec, N. J.

    1997-07-01

    Chaperonins are protein complexes that play a critical role in folding nascent polypeptides under normal conditions and refolding damaged proteins under stress conditions. In all organisms these complexes are composed of evolutionarily conserved 60-kDa proteins arranged in double-ring structures with between 7 and 9 protein subunits per ring. These double ring structures are assumed to be the functional units in vivo, although they have never been observed inside cells. Here the authors show that the purified chaperonin from the hyperthermophilic archaeon Sulfolobus shibatae, which is closely related to chaperonins in eukaryotes, has a double ring structure at low concentrations (0.1 mg/ml), but at more physiological concentrations, the rings stack end to end to form polymers. The polymers are stable at physiological temperatures (75 C) and closely resemble structures observed inside unfixed S. shibatae cells. The authors suggest that in vivo chaperonin activity may be regulated by polymerization and that chaperonin polymers may act as a cytoskeleton-like structure in archaea and bacteria.

  20. Functions of the intermediate filament cytoskeleton in the eye lens

    OpenAIRE

    Song, Shuhua; Landsbury, Andrew; Dahm, Ralf; Liu, Yizhi; Zhang, Qingjiong; Quinlan, Roy A.

    2009-01-01

    Intermediate filaments (IFs) are a key component of the cytoskeleton in virtually all vertebrate cells, including those of the lens of the eye. IFs help integrate individual cells into their respective tissues. This Review focuses on the lens-specific IF proteins beaded filament structural proteins 1 and 2 (BFSP1 and BFSP2) and their role in lens physiology and disease. Evidence generated in studies in both mice and humans suggests a critical role for these proteins and their filamentous poly...

  1. Two new isoforms of the human hepatoma-derived growth factor interact with components of the cytoskeleton.

    Science.gov (United States)

    Nüße, Jessica; Mirastschijski, Ursula; Waespy, Mario; Oetjen, Janina; Brandes, Nadine; Rebello, Osmond; Paroni, Federico; Kelm, Sørge; Dietz, Frank

    2016-05-01

    Hepatoma-derived growth factor (HDGF) is involved in diverse, apparently unrelated processes, such as cell proliferation, apoptosis, DNA-repair, transcriptional control, ribosome biogenesis and cell migration. Most of the interactions of HDGF with diverse molecules has been assigned to the hath region of HDGF. In this study we describe two previously unknown HDGF isoforms, HDGF-B and HDGF-C, generated via alternative splicing with structurally unrelated N-terminal regions of their hath region, which is clearly different from the well described isoform, HDGF-A. In silico modeling revealed striking differences near the PHWP motif, an essential part of the binding site for glycosaminoglycans and DNA/RNA. This observation prompted the hypothesis that these isoforms would have distinct interaction patterns with correspondingly diverse roles on cellular processes. Indeed, we discovered specific associations of HDGF-B and HDGF-C with cytoskeleton elements, such as tubulin and dynein, suggesting previously unknown functions of HDGF in retrograde transport, site directed localization and/or cytoskeleton organization. In contrast, the main isoform HDGF-A does not interact directly with the cytoskeleton, but via RNA with messenger ribonucleoprotein (mRNP) complexes. In summary, the discovery of HDGF splice variants with their discrete binding activities and subcellular distributions opened new avenues for understanding its biological function and importance. PMID:26845719

  2. STED Nanoscopy Reveals the Ubiquity of Subcortical Cytoskeleton Periodicity in Living Neurons

    Directory of Open Access Journals (Sweden)

    Elisa D’Este

    2015-03-01

    Full Text Available In the axons of cultured hippocampal neurons, actin forms various structures, including bundles, patches (involved in the preservation of neuronal polarity, and a recently reported periodic ring-like structure. Nevertheless, the overlaying organization of actin in neurons and in the axon initial segment (AIS is still unclear, due mainly to a lack of adequate imaging methods. By harnessing live-cell stimulated emission depletion (STED nanoscopy and the fluorescent probe SiR-Actin, we show that the periodic subcortical actin structure is in fact present in both axons and dendrites. The periodic cytoskeleton organization is also found in the peripheral nervous system, specifically at the nodes of Ranvier. The actin patches in the AIS co-localize with pre-synaptic markers. Cytosolic actin organization strongly depends on the developmental stage and subcellular localization. Altogether, the results of this study reveal unique neuronal cytoskeletal features.

  3. Regulation of cell–cell adhesion by the cadherin–catenin complex

    OpenAIRE

    Nelson, W. James

    2008-01-01

    Ca2+-dependent cell–cell adhesion is regulated by the cadherin family of cell adhesion proteins. Cadherins form trans-interactions on opposing cell surfaces which result in weak cell–cell adhesion. Stronger cell–cell adhesion occurs by clustering of cadherins and through changes in the organization of the actin cytoskeleton. Although cadherins were thought to bind directly to the actin cytoskeleton through cytoplasmic proteins, termed α- and β-catenin, recent studies with purified proteins in...

  4. MICAL, the Flavoenzyme Participating in Cytoskeleton Dynamics

    Directory of Open Access Journals (Sweden)

    Daniela Zucchini

    2013-03-01

    Full Text Available MICAL (from the Molecule Interacting with CasL indicates a family of recently discovered cytosolic, multidomain proteins, which uniquely couple an N-terminal FAD-containing monooxygenase-like domain to typical calponine homology, LIM and coiled-coil protein-interaction modules. Genetic and cell biology approaches have demonstrated an essential role of the catalytic activity of the monooxygenase-like domain in transducing the signal initiated by semaphorins interaction with their plexin receptors, which results in local actin cytoskeleton disassembly as part of fundamental processes that include differentiation, migration and cell-cell contacts in neuronal and non-neuronal cell types. This review focuses on the structure-function relations of the MICAL monooxygenase-like domain as they are emerging from the available in vitro studies on mouse, human and Drosophila MICAL forms that demonstrated a NADPH-dependent actin depolymerizing activity of MICAL. With Drosophila MICAL forms, actin depolymerization was demonstrated to be associated to conversion of Met44 to methionine sulfone through a postulated hydroxylating reaction. Arguments supporting the concept that MICAL effect on F-actin may be reversible will be discussed.

  5. Cytoskeleton, cytoskeletal interactions, and vascular endothelial function

    Directory of Open Access Journals (Sweden)

    Wang J

    2012-12-01

    Full Text Available Jingli Wang,1 Michael E Widlansky1,21Department of Medicine, Cardiovascular Medicine Division, 2Department of Pharmacology, Medical College of Wisconsin, Milwaukee, Wisconsin, USAAbstract: Far from being inert, the vascular endothelium is a critical regulator of vascular function. While the endothelium participates in autocrine, paracrine, and endocrine signaling, it also transduces mechanical signals from the cell surface involving key cell structural elements. In this review, we discuss the structure of the vascular endothelium and its relationship to traditional cardiovascular risk factors and clinical cardiovascular events. Further, we review the emerging evidence that cell structural elements, including the glycocalyx, intercellular junctions, and cytoskeleton elements, help the endothelium to communicate with its environment to regulate vascular function, including vessel permeability and signal transduction via nitric oxide bioavailability. Further work is necessary to better delineate the regulatory relationships between known key regulators of vascular function and endothelial cell structural elements.Keywords: endothelium, shear stress, eNOS, cardiovascular risk factors, glycocalyx

  6. Aging changes in organs - tissue - cells

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/004012.htm Aging changes in organs - tissue - cells To use the ... lose some function as you age during adulthood. Aging changes occur in all of the body's cells, ...

  7. Semitransparent organic solar cells with organic wavelength dependent reflectors

    NARCIS (Netherlands)

    Galagan, Y.O.; Debije, M.G.; Blom, P.W.M.

    2011-01-01

    Semitransparent organic solar cells employing solution-processable organic wavelength dependent reflectors of chiral nematic (cholesteric) liquid crystals are demonstrated. The cholesteric liquid crystal (CLC) reflects only in a narrow band of the solar spectrum and remains transparent for the remai

  8. Formation of compact myelin is required for maturation of the axonal cytoskeleton

    Science.gov (United States)

    Brady, S. T.; Witt, A. S.; Kirkpatrick, L. L.; de Waegh, S. M.; Readhead, C.; Tu, P. H.; Lee, V. M.

    1999-01-01

    Although traditional roles ascribed to myelinating glial cells are structural and supportive, the importance of compact myelin for proper functioning of the nervous system can be inferred from mutations in myelin proteins and neuropathologies associated with loss of myelin. Myelinating Schwann cells are known to affect local properties of peripheral axons (de Waegh et al., 1992), but little is known about effects of oligodendrocytes on CNS axons. The shiverer mutant mouse has a deletion in the myelin basic protein gene that eliminates compact myelin in the CNS. In shiverer mice, both local axonal features like phosphorylation of cytoskeletal proteins and neuronal perikaryon functions like cytoskeletal gene expression are altered. This leads to changes in the organization and composition of the axonal cytoskeleton in shiverer unmyelinated axons relative to age-matched wild-type myelinated fibers, although connectivity and patterns of neuronal activity are comparable. Remarkably, transgenic shiverer mice with thin myelin sheaths display an intermediate phenotype indicating that CNS neurons are sensitive to myelin sheath thickness. These results indicate that formation of a normal compact myelin sheath is required for normal maturation of the neuronal cytoskeleton in large CNS neurons.

  9. The cytoskeleton of Drosophila-derived Schneider line-1 and Kc23 cells undergoes significant changes during long-term culture

    Science.gov (United States)

    Schatten, H.; Hedrick, J.; Chakrabarti, A.

    1998-01-01

    Insect cell cultures derived from Drosophila melanogaster are increasingly being used as an alternative system to mammalian cell cultures, as they are amenable to genetic manipulation. Although Drosophila cells are an excellent tool for the study of genes and expression of proteins, culture conditions have to be considered in the interpretation of biochemical results. Our studies indicate that significant differences occur in cytoskeletal structure during the long-term culture of the Drosophila-derived cell lines Schneider Line-1 (S1) and Kc23. Scanning, transmission-electron, and immunofluorescence microscopy studies reveal that microfilaments, microtubules, and centrosomes become increasingly different during the culture of these cells from 24 h to 7-14 days. Significant cytoskeletal changes are observed at the cell surface where actin polymerizes into microfilaments, during the elongation of long microvilli. Additionally, long protrusions develop from the cell surface; these protrusions are microtubule-based and establish contact with neighboring cells. In contrast, the microtubule network in the interior of the cells becomes disrupted after four days of culture, resulting in altered transport of mitochondria. Microtubules and centrosomes are also affected in a small percent of cells during cell division, indicating an instability of centrosomes. Thus, the cytoskeletal network of microfilaments, microtubules, and centrosomes is affected in Drosophila cells during long-term culture. This implies that gene regulation and post-translational modifications are probably different under different culture conditions.

  10. Protein kinase C, focal adhesions and the regulation of cell migration

    DEFF Research Database (Denmark)

    Fogh, Betina S; Multhaupt, Hinke A B; Couchman, John Robert

    2014-01-01

    Cell adhesion to extracellular matrix is a complex process involving protrusive activity driven by the actin cytoskeleton, engagement of specific receptors, followed by signaling and cytoskeletal organization. Thereafter, contractile and endocytic/recycling activities may facilitate migration and...

  11. From filaments to function:The role of the plant actin cytoskeleton in pathogen perception, signaling and immunity

    Institute of Scientific and Technical Information of China (English)

    Katie Porter; Brad Day

    2016-01-01

    The eukaryotic actin cytoskeleton is required for numerous cellular processes, including cell shape, develop-ment and movement, gene expression and signal transduc-tion, and response to biotic and abiotic stress. In recent years, research in both plants and animal systems have described a function for actin as the ideal surveillance platform, linking the function and activity of primary physiological processes to the immune system. In this review, we will highlight recent advances that have defined the regulation and breadth of function of the actin cytoskeleton as a network required for defense signaling following pathogen infection. Coupled with an overview of recent work demonstrating specific targeting of the plant actin cytoskeleton by a diversity of pathogens, including bacteria, fungi and viruses, we will highlight the importance of actin as a key signaling hub in plants, one that mediates surveillance of cellular homeostasis and the activa-tion of specific signaling responses following pathogen perception. B4ased on the studies highlighted herein, we propose a working model that posits changes in actin filament organization is in and of itself a highly specific signal, which induces, regulates and physically directs stimulus-specific signaling processes, most importantly, those associated with response to pathogens.

  12. Simulations of the erythrocyte cytoskeleton at large deformation. II. Micropipette aspiration.

    OpenAIRE

    Discher, D. E.; Boal, D H; Boey, S K

    1998-01-01

    Coarse-grained molecular models of the erythrocyte membrane's spectrin cytoskeleton are presented in Monte Carlo simulations of whole cells in micropipette aspiration. The nonlinear chain elasticity and sterics revealed in more microscopic cytoskeleton models (developed in a companion paper; Boey et al., 1998. Biophys. J. 75:1573-1583) are faithfully represented here by two- and three-body effective potentials. The number of degrees of freedom of the system are thereby reduced to a range that...

  13. Combined effect of cortical cytoskeleton and transmembrane proteins on domain formation in biomembranes

    Science.gov (United States)

    Sikder, Md. Kabir Uddin; Stone, Kyle A.; Kumar, P. B. Sunil; Laradji, Mohamed

    2014-08-01

    We investigate the combined effects of transmembrane proteins and the subjacent cytoskeleton on the dynamics of phase separation in multicomponent lipid bilayers using computer simulations of a particle-based implicit solvent model for lipid membranes with soft-core interactions. We find that microphase separation can be achieved by the protein confinement by the cytoskeleton. Our results have relevance to the finite size of lipid rafts in the plasma membrane of mammalian cells.

  14. Combined effect of cortical cytoskeleton and transmembrane proteins on domain formation in biomembranes

    DEFF Research Database (Denmark)

    Sikder, K. U.; Stone, K. A.; Kumar, P. B. S.;

    2014-01-01

    We investigate the combined effects of transmembrane proteins and the subjacent cytoskeleton on the dynamics of phase separation in multicomponent lipid bilayers using computer simulations of a particle-based implicit solvent model for lipid membranes with soft-core interactions. We find that...... microphase separation can be achieved by the protein confinement by the cytoskeleton. Our results have relevance to the finite size of lipid rafts in the plasma membrane of mammalian cells. (C) 2014 AIP Publishing LLC....

  15. Exploring nanoscale properties of organic solar cells

    OpenAIRE

    Mönch, Tobias

    2015-01-01

    The demand for electrical energy is steadily increasing. Highly efficient organic solar cells based on mixed, strongly absorbing organic molecules convert sunlight into electricity and, thus, have the potential to contribute to the worlds energy production. The continuous development of new materials during the last decades lead to a swift increase of power conversion efficiencies (PCE) of organic solar cells, recently reaching 12%. Despite these breakthroughs, the usage of highly complex...

  16. Acute and chronic effects of exposure to a 1-mT magnetic field on the cytoskeleton, stress proteins, and proliferation of astroglial cells in culture

    International Nuclear Information System (INIS)

    This paper reports the effects of exposure to static, sinusoidal (50 Hz), and combined static/sinusoidal magnetic fields on cultured astroglial cells. Confluent primary cultures of astroglial cells were exposed to a 1-mT sinusoidal, static, or combined magnetic field for 1 h. In another experiment, cells were exposed to the combined magnetic field for 1, 2, and 4 h. The hsp25, hsp60, hsp70, actin, and glial fibrillary acidic protein contents of the astroglial cells were determined by immunoblotting 24 h after exposure. No significant differences were seen between control and exposed cells with respect to their contents of these proteins, neither were any changes in cell morphology observed. In a third experiment to determine the effect of a chronic (11-day) exposure to a combined 1-mT static/sinusoidal magnetic field on the proliferation of cultured astroglial cells, no significant differences were seen between control, sham-exposed, or exposed cells. These results suggest that exposure to 1-mT sinusoidal, static, or combined magnetic fields has no significant effects on the stress, cytoskeletal protein levels in, or proliferation of cultured astroglial cells

  17. 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.

  18. Organic Based Solar Cells with Morphology Control

    DEFF Research Database (Denmark)

    Andersen, Thomas Rieks

    Microscopy and as solar cells in a blend with PCBM. It was concluded that these particles did not show a potential large enough for continuous work due to a high material loss and low efficiency when applied in solar cells. The second method to achieve was preparation of pre-arranged morphology organic......The field of organic solar cells has in the last years gone through an impressive development with efficiencies reported up to 12 %. For organic solar cells to take the leap from primarily being a laboratory scale technology to being utilized as renewable energy source, several issues need to be...... nanoparticles consisting of a blend of donor and acceptor in an aqueous dispersion, thereby addressing two of the issues remaining in the field of organic solar cells. This approach was used on six different polymers, which all had the ability to prepare aqueous nanoparticle inks. The morphology of the...

  19. On the role of the plasmodial cytoskeleton in facilitating intelligent behavior in slime mold Physarum polycephalum.

    Science.gov (United States)

    Mayne, Richard; Adamatzky, Andrew; Jones, Jeff

    2015-01-01

    The plasmodium of slime mold Physarum polycephalum behaves as an amorphous reaction-diffusion computing substrate and is capable of apparently 'intelligent' behavior. But how does intelligence emerge in an acellular organism? Through a range of laboratory experiments, we visualize the plasmodial cytoskeleton-a ubiquitous cellular protein scaffold whose functions are manifold and essential to life-and discuss its putative role as a network for transducing, transmitting and structuring data streams within the plasmodium. Through a range of computer modeling techniques, we demonstrate how emergent behavior, and hence computational intelligence, may occur in cytoskeletal communications networks. Specifically, we model the topology of both the actin and tubulin cytoskeletal networks and discuss how computation may occur therein. Furthermore, we present bespoke cellular automata and particle swarm models for the computational process within the cytoskeleton and observe the incidence of emergent patterns in both. Our work grants unique insight into the origins of natural intelligence; the results presented here are therefore readily transferable to the fields of natural computation, cell biology and biomedical science. We conclude by discussing how our results may alter our biological, computational and philosophical understanding of intelligence and consciousness. PMID:26478782

  20. Organic solar cells fundamentals, devices, and upscaling

    CERN Document Server

    Rand, Barry P

    2014-01-01

    Solution-Processed DonorsB. Burkhart, B. C. ThompsonSmall-Molecule and Vapor-Deposited Organic Photovoltaics R. R. Lunt, R. J. HolmesAcceptor Materials for Solution-Processed Solar Cells Y. HeInterfacial Layers R. Po, C. Carbonera, A. BernardiElectrodes in Organic Photovoltaic Cells S. Yoo, J.-Y. Lee, H. Kim, J. LeeTandem and Multi-Junction Organic Solar Cells J. Gilot, R. A. J. JanssenBulk Heterojunction Morphology Control and Characterization T. Wang, D. G. LidzeyOptical Modeling and Light Management

  1. Generation of functional organs from stem cells

    Directory of Open Access Journals (Sweden)

    Liu Yunying

    2013-01-01

    Full Text Available Abstract We are now well entering the exciting era of stem cells. Potential stem cell therapy holds great promise for the treatment of many diseases such as stroke, traumatic brain injury, Alzheimer’s disease, Parkinson’s disease, amyotrophic lateral-sclerosis, myocardial infarction, muscular dystrophy, diabetes, and etc. It is generally believed that transplantation of specific stem cells into the injured tissue to replace the lost cells is an effective way to repair the tissue. In fact, organ transplantation has been successfully practiced in clinics for liver or kidney failure. However, the severe shortage of donor organs has been a major obstacle for the expansion of organ transplantation programs. Toward that direction, generation of transplantable organs using stem cells is a desirable approach for organ replacement and would be of great interest for both basic and clinical scientists. Here we review recent progress in the field of organ generation using various methods including single adult tissue stem cells, a blastocyst complementation system, tissue decellularization/recellularization and a combination of stem cells and tissue engineering.

  2. Organic fuel cell methods and apparatus

    Science.gov (United States)

    Vamos, Eugene (Inventor); Surampudi, Subbarao (Inventor); Narayanan, Sekharipuram R. (Inventor); Frank, Harvey A. (Inventor); Halpert, Gerald (Inventor); Olah, George A. (Inventor); Prakash, G. K. Surya (Inventor)

    2008-01-01

    A liquid organic, fuel cell is provided which employs a solid electrolyte membrane. An organic fuel, such as a methanol/water mixture, is circulated past an anode of a cell while oxygen or air is circulated past a cathode of the cell. The cell solid electrolyte membrane is preferably fabricated from Nafion.TM.. Additionally, a method for improving the performance of carbon electrode structures for use in organic fuel cells is provided wherein a high surface-area carbon particle/Teflon.TM.-binder structure is immersed within a Nafion.TM./methanol bath to impregnate the electrode with Nafion.TM.. A method for fabricating an anode for use in a organic fuel cell is described wherein metal alloys are deposited onto the electrode in an electro-deposition solution containing perfluorooctanesulfonic acid. A fuel additive containing perfluorooctanesulfonic acid for use with fuel cells employing a sulfuric acid electrolyte is also disclosed. New organic fuels, namely, trimethoxymethane, dimethoxymethane, and trioxane are also described for use with either conventional or improved fuel cells.

  3. Fabrication and Characterization of Organic Solar Cells

    OpenAIRE

    Yengel, Emre

    2010-01-01

    Bulk heterojunction organic solar cells have recently drawn tremendous attention because of their technological advantages for actualization of large-area and cost effective fabrication. Two important criteria of these cells are efficiency and cost. The research in this dissertation focuses on the enhancement of these criteria with two different approaches. In the first approach, power conversion efficiency of organic photovoltaic devices is enhanced by introducing Deoxyribonucleic acids DNA ...

  4. Membrane Organization and Dynamics in Cell Polarity

    OpenAIRE

    Orlando, Kelly; Guo, Wei

    2009-01-01

    The establishment and maintenance of cell polarity is important to a wide range of biological processes ranging from chemotaxis to embryogenesis. An essential feature of cell polarity is the asymmetric organization of proteins and lipids in the plasma membrane. In this article, we discuss how polarity regulators such as small GTP-binding proteins and phospholipids spatially and kinetically control vesicular trafficking and membrane organization. Conversely, we discuss how membrane trafficking...

  5. Organic fuel cells and fuel cell conducting sheets

    Science.gov (United States)

    Masel, Richard I.; Ha, Su; Adams, Brian

    2007-10-16

    A passive direct organic fuel cell includes an organic fuel solution and is operative to produce at least 15 mW/cm.sup.2 when operating at room temperature. In additional aspects of the invention, fuel cells can include a gas remover configured to promote circulation of an organic fuel solution when gas passes through the solution, a modified carbon cloth, one or more sealants, and a replaceable fuel cartridge.

  6. Organic solar cells: Going green

    Science.gov (United States)

    Luo, Guoping; Wu, Hongbin

    2016-02-01

    High-performance polymer solar cells are normally processed with halogenated solvents, which are toxic and hazardous. Now, high power-conversion efficiency in bulk-heterojunction devices is achieved by using a non-toxic hydrocarbon solvent through an environmentally friendly processing route.

  7. Fullerene based organic solar cells

    NARCIS (Netherlands)

    Popescu, Lacramioara Mihaela

    2008-01-01

    The direct conversion of the sunlight into electricity is the most elegant process to generate environmentally-friendly renewable energy. Plastic solar cells offer the prospect of flexible, lightweight, lower cost of manufacturing, and hopefully an efficient way to produce electricity from sunlight.

  8. Polysaccharide-capped silver Nanoparticles inhibit biofilm formation and eliminate multi-drug-resistant bacteria by disrupting bacterial cytoskeleton with reduced cytotoxicity towards mammalian cells

    Science.gov (United States)

    Sanyasi, Sridhar; Majhi, Rakesh Kumar; Kumar, Satish; Mishra, Mitali; Ghosh, Arnab; Suar, Mrutyunjay; Satyam, Parlapalli Venkata; Mohapatra, Harapriya; Goswami, Chandan; Goswami, Luna

    2016-01-01

    Development of effective anti-microbial therapeutics has been hindered by the emergence of bacterial strains with multi-drug resistance and biofilm formation capabilities. In this article, we report an efficient green synthesis of silver nanoparticle (AgNP) by in situ reduction and capping with a semi-synthetic polysaccharide-based biopolymer (carboxymethyl tamarind polysaccharide). The CMT-capped AgNPs were characterized by UV, DLS, FE-SEM, EDX and HR-TEM. These AgNPs have average particle size of ~20–40 nm, and show long time stability, indicated by their unchanged SPR and Zeta-potential values. These AgNPs inhibit growth and biofilm formation of both Gram positive (B. subtilis) and Gram negative (E. coli and Salmonella typhimurium) bacterial strains even at concentrations much lower than the minimum inhibitory concentration (MIC) breakpoints of antibiotics, but show reduced or no cytotoxicity against mammalian cells. These AgNPs alter expression and positioning of bacterial cytoskeletal proteins FtsZ and FtsA. CMT-capped AgNPs can effectively block growth of several clinical isolates and MDR strains representing different genera and resistant towards multiple antibiotics belonging to different classes. We propose that the CMT-capped AgNPs can have potential bio-medical application against multi-drug-resistant microbes with minimal cytotoxicity towards mammalian cells. PMID:27125749

  9. Polysaccharide-capped silver Nanoparticles inhibit biofilm formation and eliminate multi-drug-resistant bacteria by disrupting bacterial cytoskeleton with reduced cytotoxicity towards mammalian cells

    Science.gov (United States)

    Sanyasi, Sridhar; Majhi, Rakesh Kumar; Kumar, Satish; Mishra, Mitali; Ghosh, Arnab; Suar, Mrutyunjay; Satyam, Parlapalli Venkata; Mohapatra, Harapriya; Goswami, Chandan; Goswami, Luna

    2016-04-01

    Development of effective anti-microbial therapeutics has been hindered by the emergence of bacterial strains with multi-drug resistance and biofilm formation capabilities. In this article, we report an efficient green synthesis of silver nanoparticle (AgNP) by in situ reduction and capping with a semi-synthetic polysaccharide-based biopolymer (carboxymethyl tamarind polysaccharide). The CMT-capped AgNPs were characterized by UV, DLS, FE-SEM, EDX and HR-TEM. These AgNPs have average particle size of ~20–40 nm, and show long time stability, indicated by their unchanged SPR and Zeta-potential values. These AgNPs inhibit growth and biofilm formation of both Gram positive (B. subtilis) and Gram negative (E. coli and Salmonella typhimurium) bacterial strains even at concentrations much lower than the minimum inhibitory concentration (MIC) breakpoints of antibiotics, but show reduced or no cytotoxicity against mammalian cells. These AgNPs alter expression and positioning of bacterial cytoskeletal proteins FtsZ and FtsA. CMT-capped AgNPs can effectively block growth of several clinical isolates and MDR strains representing different genera and resistant towards multiple antibiotics belonging to different classes. We propose that the CMT-capped AgNPs can have potential bio-medical application against multi-drug-resistant microbes with minimal cytotoxicity towards mammalian cells.

  10. Polysaccharide-capped silver Nanoparticles inhibit biofilm formation and eliminate multi-drug-resistant bacteria by disrupting bacterial cytoskeleton with reduced cytotoxicity towards mammalian cells.

    Science.gov (United States)

    Sanyasi, Sridhar; Majhi, Rakesh Kumar; Kumar, Satish; Mishra, Mitali; Ghosh, Arnab; Suar, Mrutyunjay; Satyam, Parlapalli Venkata; Mohapatra, Harapriya; Goswami, Chandan; Goswami, Luna

    2016-01-01

    Development of effective anti-microbial therapeutics has been hindered by the emergence of bacterial strains with multi-drug resistance and biofilm formation capabilities. In this article, we report an efficient green synthesis of silver nanoparticle (AgNP) by in situ reduction and capping with a semi-synthetic polysaccharide-based biopolymer (carboxymethyl tamarind polysaccharide). The CMT-capped AgNPs were characterized by UV, DLS, FE-SEM, EDX and HR-TEM. These AgNPs have average particle size of ~20-40 nm, and show long time stability, indicated by their unchanged SPR and Zeta-potential values. These AgNPs inhibit growth and biofilm formation of both Gram positive (B. subtilis) and Gram negative (E. coli and Salmonella typhimurium) bacterial strains even at concentrations much lower than the minimum inhibitory concentration (MIC) breakpoints of antibiotics, but show reduced or no cytotoxicity against mammalian cells. These AgNPs alter expression and positioning of bacterial cytoskeletal proteins FtsZ and FtsA. CMT-capped AgNPs can effectively block growth of several clinical isolates and MDR strains representing different genera and resistant towards multiple antibiotics belonging to different classes. We propose that the CMT-capped AgNPs can have potential bio-medical application against multi-drug-resistant microbes with minimal cytotoxicity towards mammalian cells. PMID:27125749

  11. The Role of Molecular Microtubule Motors and the Microtubule Cytoskeleton in Stress Granule Dynamics

    Directory of Open Access Journals (Sweden)

    Kristen M. Bartoli

    2011-01-01

    Full Text Available Stress granules (SGs are cytoplasmic foci that appear in cells exposed to stress-induced translational inhibition. SGs function as a triage center, where mRNAs are sorted for storage, degradation, and translation reinitiation. The underlying mechanisms of SGs dynamics are still being characterized, although many key players have been identified. The main components of SGs are stalled 48S preinitiation complexes. To date, many other proteins have also been found to localize in SGs and are hypothesized to function in SG dynamics. Most recently, the microtubule cytoskeleton and associated motor proteins have been demonstrated to function in SG dynamics. In this paper, we will discuss current literature examining the function of microtubules and the molecular microtubule motors in SG assembly, coalescence, movement, composition, organization, and disassembly.

  12. Post-polymerization crosstalk between the actin cytoskeleton and microtubule network.

    Science.gov (United States)

    Joo, E Emily; Yamada, Kenneth M

    2016-05-01

    Cellular cytoskeletal systems play many pivotal roles in living organisms by controlling cell shape, division, and migration, which ultimately govern morphology, physiology, and functions of animals. Although the cytoskeletal systems are distinct and play different roles, there is growing evidence that these diverse cytoskeletal systems coordinate their functions with each other. This coordination between cytoskeletal systems, often termed cytoskeletal crosstalk, has been identified when the dynamic state of one individual system affects the other system. In this review, we briefly describe some well-established examples of crosstalk between cytoskeletal systems and then introduce a newly discovered form of crosstalk between the actin cytoskeleton and microtubule network that does not appear to directly alter polymerization or depolymerization of either system. The biological impact and possible significance of this post-polymerization crosstalk between actin and microtubules will be discussed in detail. PMID:27058810

  13. Studies on the mechanisms of activation of potassium efflux and receptor-cytoskeleton association by aggregated immunoglobulin E-receptor complexes on rat basophilic leukemia cells

    International Nuclear Information System (INIS)

    Evidence for the activation of an outwardly-directed K+ permeability pathway was obtained by studying changes in plasma membrane potential that result from the aggregation of immunoglobulin E-complexes on rat basophilic leukemia cells. With the potential-sensitive dye, bisoxonol, we observe that activation by multivalent antigen causes membrane depolarization that is followed by a return towards the resting potential that we term repolarization. The depolarization response may reflect a Ca2+ influx pathway, and it exhibits the same antigen-dose dependence and temperature dependence as the degranulation response. The polarization phase of the membrane potential response is selectively inhibited by the K+ channel blockers quinidine and Ba2+ in parallel with their inhibition of the degranulation response, suggesting an important role for a K+ efflux pathway in antigen-stimulated degranulation. 86Rb+ efflux measurements were used to characterize the K+ permeability pathways responsible for the repolarization response

  14. Porcine reproductive and respiratory syndrome virus (PRRSV) infection spreads by cell-to-cell transfer in cultured MARC-145 cells, is dependent on an intact cytoskeleton, and is suppressed by drug-targeting of cell permissiveness to virus infection

    OpenAIRE

    Rowland Raymond RR; Ward-Demo Pam; Said Suleman; Wong Grace HW; Duman Richard G; Cafruny William A; Nelson Eric A

    2006-01-01

    Abstract Background Porcine reproductive and respiratory syndrome virus (PRRSV) is the etiologic agent of PRRS, causing widespread chronic infections which are largely uncontrolled by currently available vaccines or other antiviral measures. Cultured monkey kidney (MARC-145) cells provide an important tool for the study of PRRSV replication. For the present study, flow cytometric and fluorescence antibody (FA) analyses of PRRSV infection of cultured MARC-145 cells were carried out in experime...

  15. Immunolocation of mitochondria-rich cells in epidermis of the common toad, Bufo bufo L

    DEFF Research Database (Denmark)

    Spies, Ingrid B.M.

    Adult toads, skin, flask-shaped cells, cytoskeleton, keratin expression, immunohistochemistry, differentiation.......Adult toads, skin, flask-shaped cells, cytoskeleton, keratin expression, immunohistochemistry, differentiation....

  16. The effects of 60Co γ-ray irradiation on the cytoskeleton of mouse peritoneal macrophages and human peripheral blood monocytes in vitro

    International Nuclear Information System (INIS)

    The whole mount cell electron microscopy in combination with selective extraction method for preparing cytoskeletal framework was applied. Cy toskeleton prepared by Triton X-100 treatment of mouse peritoneal macrophages and human peripheral blood monocytes appeared in electron microscopy as a highly organized and interconnected three-dimensional matrix of different fibrous elements. Since such cytoskeletons are open membrane-free system, individual fibrous organizations can be identified by specific antibodies. An indirect immunogold procedure using monoclonal anti-tubulin or anti-actin antibodies was applied to visualize tubulin-or actin-containing structures. The three-dimensional visualization of Triton X-100 resistant cytoskeletons had been used to demonstrate that different doses of 60Co γ-ray caused a distinctive and reproducible alterations of the cytoskeletons of intact mouse peritoneal macrophages and human peripheral blood monocytes in vitro. The results showed that there were some similar alterations with those caused by cytochalasin B and by colchicine. From these observations and other workers' studies, it's likely that 60Co γ-ray irradiation may inhibit cytoplasmic microtubule and microfilament assembling

  17. Rearrangements of microtubule cytoskeleton in stomatal closure of Arabidopsis induced by nitric oxide

    Institute of Scientific and Technical Information of China (English)

    ZHANG YongMei; WU ZhongYi; WANG XueChen; YU Rong

    2008-01-01

    NO (nitric oxide), known as a key signal molecule in plant, plays important roles in regulation of stomatal movement. In this study, microtubule dynamics and its possible mechanism in the NO signal pathway were investigated. The results were as follows: (ⅰ) In vivo stomatal aperture assays revealed that both vinblastine (microtubule-disrupting drug) and SNP (exogenous NO donor) prevented stomatal opening in the light, and vinblastine even could enhance the inhibitory effect of SNP, whereas taxol (a microtubule-stabilizing agent) was able to reduce this effect; (ⅱ) microtubules in the opening Arabi-dopsis guard cells expressing GFP:α-tubulin-6 (AtGFP:α-tubulin-6) were organized in parallel, straight and dense bundles, radiating from the ventral side to the dorsal side, and most of them were localized perpendicularly to the ventral wall; (ⅲ) under the same environmental conditions, treated with SNP for 30 min, the radial arrays of microtubules in guard cells began to break down, twisted partially and be-came oblique or exhibited a random pattern; (ⅳ) furthermore, the involvement of cytosolic Ca2+ in this event was tested. Stomatal aperture assays revealed that BAPTA-AM (a chelator of Ca2+) greatly sup-pressed the effect of NO on stomatal closure; however, it did not show the same function on stomatal closure induced by vinblastine. When BAPTA-AM was added to the SNP-pretreated solution, the SNP-induced disordered microtubulue cytoskeleton in guard cells underwent rearrangement in a time-dependent manner. After 30 min of treatment with BAPTA-AM, the cortical microtubules resumed the original radial distribution, almost the same as the control. All this indicates that NO may promote rearrangement of microtubule cytoskeleton via elevation of [Ca2+]cyt (free Ca2+ concentration in the cy-toplasm), finally leading to stomatal closure.

  18. Organic electrolyte for nonaqueous cells

    Energy Technology Data Exchange (ETDEWEB)

    Blomgren, G.E.; Leger, V.Z.

    1989-02-28

    A nonaqueous electrolyte solution, for nonaqueous cells is described comprising a solute dissolved in a solvent, the solvent comprising at least one diether in which two oxygen atoms are separated by two carbon atoms in the sequence O/sub 1/C/sub 1/C/sub 2/O/sub 2/ and in which two or three contiguous atoms of the sequence are contained in a ring system of five, six or seven members in which the remaining ring atoms are carbon, or carbon and hetero atoms. When the oxygen atom O/sub 1/ or O/sub 2/, or oxygen atoms O/sub 1/ and O/sub 2/, are not included in the ring structure, a methyl group is bonded to the oxygen atom or atoms. The electrolyte solution contains at least one cosolvent selected from the group consisting of sulfolane, 3-methyl sulfolane; tetrahydrofuran; 2-methyltetrahydrofuran; 1,3-dioxolane; 3-methyl-oxazolidone; propylene carbonate; ..gamma.. (gamma)-butyrolactone; ..gamma.. (gamma)-valerolactone; ethylene glycol dimethylsulfite; dimethyl sulfoxide; and 1,1- and 1.2-dimethoxyethane.

  19. Transparent Electrodes for Organic Solar Cells

    OpenAIRE

    Selzer, Franz

    2016-01-01

    The aim of this work was to investigate silver nanowire as well as carbon nanotube networks as transparent conducting electrodes for small molecule organic solar cells. In the framework of the nanowire investigations, a low-temperature method at less than 80 °C is developed to obtain highly conductive networks directly after the deposition and without post-processing. In detail, specific non-conductive organic materials act as a matrix where the nanowires are embedded in such that a mutua...

  20. Concentrated sunlight for organic solar cells

    DEFF Research Database (Denmark)

    Tromholt, Thomas

    2010-01-01

    Concentrated sunlight provides a novel approach to the study of the physical and electrical parameters of organic solar cells. The study of performance of organic solar cells at high solar concentrations provides insight into the physics, which cannot be studied with conventional solar simulators....... A high solar intensity study of inverted P3HT:PCBM solar cells is presented. Performance peak positions were found to be in the range of 1-5 suns, with smaller cells peaking at higher solar concentrations. Additionally, concentrated sunlight is demonstrated as a practical tool for accelerated...... polymers were degraded resulting in acceleration factors in the range of 19-55. This shows that concentrated sunlight can be used as qualitatively to determine the lifetime of polymers under highly accelerated conditions....

  1. Cytoskeleton in gravisensing and signal transductionof lower plants

    Science.gov (United States)

    Braun, M.

    Characean rhizoids and protonemata are favourable cell types for studying tip growth and gravisensing. Both processes are highly dependent on the actin cytoskeleton. The multiple functions and different arrangements of actin in both cell types are regulated by the concerted action of actin-binding proteins. Monomer- binding profilin is distributed evenly throughout the cytoplasm and is likely to be involved in the regulation of the polymerization state of actin. Actin-severing ADF, spectrin- and actinin-like epitopes concentrate in a central prominent spot in the apex of both cell types, where they colocalize with a dense, spherical actin array and a unique aggregation of endoplasmic reticulum (ER), the structural center of the tip - growth organizing Spitzenkörper. The ER aggregate disintegrates and immuno- localization of the actin-binding proteins fails when tip growth is arrested; the epitopes reappear when tip growth resumes. Actin filaments form a meshwork of axially oriented filaments in the subapical zone and focus in this central apical area which seems to represent their apical polymerization site. The rapid turn-over and rearrangement of actin might be under control of ADF and profilin. Spectrin- and actinin-like proteins are candidates for establishing the actin-mediated anchoring and maintaining of the ER aggregate. They could also provide a mechanism for recruiting specific membrane proteins that create the particular physiological environment for gravity-oriented tip growth. The positioning and sedimentation of statoliths in the subapical region (crucial for gravisensing) is highly coordinated by actomyosin. Non-invasive infrared laser micromanipulation techniques, centri- fugation and experiments in microgravity revealed that reorientation of the growth direction was initiated when at least 2-3 statoliths were directed to specific areas of the plasma membrane by actomyosin and gravitational forces. The statolith-sensitive area is confined to the

  2. Gametophytic development of Brassica napus pollen in vitroenables examination of cytoskeleton and nuclear movements.

    Science.gov (United States)

    Dubas, Ewa; Wedzony, Maria; Custers, Jan; Kieft, Henk; van Lammeren, André A M

    2012-04-01

    Isolated microspores and pollen suspension of Brassica napus "Topas" cultured in NLN-13 medium at 18°C follow gametophytic pathway and develop into pollen grains closely resembling pollen formed in planta. This culture system complemented with whole-mount immunocytochemical technology and novel confocal laser scanning optical technique enables detailed studies of male gametophyte including asymmetric division, cytoskeleton, and nuclear movements. Microtubular cytoskeleton configurationally changed in successive stages of pollen development. The most prominent role of microtubules (MTs) was observed just before and during nuclear migration at the early and mid-bi-cellular stage. At the early bi-cellular stage, parallel arrangement of cortical and endoplasmic MTs to the long axis of the generative cell (GC) as well as MTs within GC under the plasmalemma bordering vegetative cell (VC) were responsible for GC lens shape. At the beginning of the GC migration, endoplasmic microtubules (EMTs) of the VC radiated from the nuclear envelope. Most cortical and EMTs of the VC were found near the sporoderm. At the same time, pattern of MTs observed in GC was considerably different. Multiple EMTs of the GC, previously parallel aligned, reorganized, and start to surround GC, forming a basket-like structure. These results suggest that EMTs of GC provoke changes in GC shape, its detachment from the sporoderm, and play an important role in GC migration to the vegetative nucleus (VN). During the process of migration of the GC to the VC, multiple and thick bundles of MTs, radiating from the cytoplasm near GC plasma membrane, arranged perpendicular to the narrow end of the GC and organized into a "comet-tail" form. These GC "tail" MTs became shortened and the generative nucleus (GN) took a ball shape. The dynamic changes of MTs accompanied polarized distribution pattern of mitochondria and endoplasmic reticulum. In order to confirm the role of MTs in pollen development, a "whole

  3. The cytoskeleton of digitonin-treated rat hepatocytes.

    Science.gov (United States)

    Fiskum, G; Craig, S W; Decker, G L; Lehninger, A L

    1980-06-01

    Treatment of isolated rat hepatocptes with low concentrations of digitonin increases the permeability of the plsma membrane to cytosolic proteins without causing release of organelles such as mitochondria into the surrounding medium. Electron microscopy showed that treatment of the cells with increasing concentations of digitonin results in a progressive loss in the continuity of the plasma membrane, while most other aspects of cellular morphology remain normal. Depletion of background staining material from the cytosol by digitonin treatment of the cells greatly enhances the visualization of the cytoskeleton. The use of this technique, together with immunofluorescent light microscopy, has verified the presence of an actin-containing filamentous network at the hepatocyte cortex as well as intermediate filaments distributed throughout the cell. Digitonin is thus useful both for selectively permeabilizing the plasma membrane and for intensifying the appearance of intracellular structures such as microfilaments that are normally difficult to observe in cells such as hepatocytes. PMID:6997878

  4. Organization of microtubules in cochlear hair cells.

    Science.gov (United States)

    Furness, D N; Hackney, C M; Steyger, P S

    1990-07-01

    The organization of microtubules in hair cells of the guinea-pig cochlea has been investigated using transmission electron microscopy and correlated with the location of tubulin-associated immunofluorescence in surface preparations of the organ of Corti. Results from both techniques reveal consistent distributions of microtubules in inner and outer hair cells. In the inner hair cells, microtubules are most concentrated in the apex. Reconstruction from serial sections shows three main groups: firstly, in channels through the cuticular plate and in a discontinuous belt around its upper perimeter; secondly, forming a ring inside a rim extending down from the lower perimeter of the plate; and thirdly, in a meshwork underlying the main body of the plate. In the cell body, microtubules line the inner face of the subsurface cistern and extend longitudinally through a tubulo-vesicular track between the apex and base. In outer hair cells, the pattern of microtubules associated with the cuticular plate is similar, although there are fewer present than in inner hair cells. In outer hair cells from the apex of the cochlea, microtubules occur around an infracuticular protrusion of cuticular plate material. In the cell body, many more microtubules occur in the region below the nucleus compared with inner hair cells. The possible functions of microtubules in hair cells are discussed by comparison with those found in other systems. These include morphogenesis and maintenance of cell shape; intracellular transport, e.g., of neurotransmitter vesicles; providing a possible substrate for motility; mechanical support of structures associated with sensory transduction. PMID:2197374

  5. Mechanics and control of the cytoskeleton in Amoeba proteus.

    Science.gov (United States)

    Dembo, M

    1989-06-01

    Many models of the cytoskeletal motility of Amoeba proteus can be formulated in terms of the theory of reactive interpenetrating flow (Dembo and Harlow, 1986). We have devised numerical methodology for testing such models against the phenomenon of steady axisymmetric fountain flow. The simplest workable scheme revealed by such tests (the minimal model) is the main preoccupation of this study. All parameters of the minimal model are determined from available data. Using these parameters the model quantitatively accounts for the self assembly of the cytoskeleton of A. proteus: for the formation and detailed morphology of the endoplasmic channel, the ectoplasmic tube, the uropod, the plasma gel sheet, and the hyaline cap. The model accounts for the kinematics of the cytoskeleton: the detailed velocity field of the forward flow of the endoplasm, the contraction of the ectoplasmic tube, and the inversion of the flow in the fountain zone. The model also gives a satisfactory account of measurements of pressure gradients, measurements of heat dissipation, and measurements of the output of useful work by amoeba. Finally, the model suggests a very promising (but still hypothetical) continuum formulation of the free boundary problem of amoeboid motion. by balancing normal forces on the plasma membrane as closely as possible, the minimal model is able to predict the turgor pressure and surface tension of A. proteus. Several dynamical factors are crucial to the success of the minimal model and are likely to be general features of cytoskeletal mechanics and control in amoeboid cells. These are: a constitutive law for the viscosity of the contractile network that includes an automatic process of gelation as the network density gets large; a very vigorous cycle of network polymerization and depolymerization (in the case of A. proteus, the time constant for this reaction is approximately 12 s); control of network contractility by a diffusible factor (probably calcium ion); and

  6. Organic Tandem Solar Cells: Design and Formation

    Science.gov (United States)

    Chen, Chun-Chao

    In the past decade, research on organic solar cells has gone through an important development stage leading to major enhancements in power conversion efficiency, from 4% to 9% in single-junction devices. During this period, there are many novel processing techniques and device designs that have been proposed and adapted in organic solar-cell devices. One well-known device architecture that helps maximize the solar cell efficiency is the multi-junction tandem solar-cell design. Given this design, multiple photoactive absorbers as subcells are stacked in a monolithic fashion and assembled via series connection into one complete device, known as the tandem solar cell. Since multiple absorbers with different optical energy bandgaps are being applied in one tandem solar-cell device, the corresponding solar cell efficiency is maximized through expanded absorption spectrum and reduced carrier thermalization loss. In Chapter 3, the architecture of solution-processible, visibly transparent solar cells is introduced. Unlike conventional organic solar-cell devices with opaque electrodes (such as silver, aluminum, gold and etc.), the semi-transparent solar cells rely on highly transparent electrodes and visibly transparent photoactive absorbers. Given these two criteria, we first demonstrated the visibly transparent single-junction solar cells via the polymer absorber with near-infrared absorption and the top electrode based on solution-processible silver nanowire conductor. The highest visible transparency (400 ˜ 700 nm) of 65% was achieved for the complete device structure. More importantly, power conversion efficiency of 4% was also demonstrated. In Chapter 4, we stacked two semi-transparent photoactive absorbers in the tandem architecture in order to realize the semi-transparent tandem solar cells. A noticeable performance improvement from 4% to 7% was observed. More importantly, we modified the interconnecting layers with the incorporation of a thin conjugated

  7. Toxic effect of zinc nanoscale metal-organic frameworks on rat pheochromocytoma (PC12) cells in vitro

    International Nuclear Information System (INIS)

    Highlights: • Metal-organic frameworks (MOFs) represent a newborn family of hybrid materials. • MOFs have already shown promise in a number of biological applications. • The biological applications of MOFs raise concerns for potential cytotoxicity. • Substantial information about MOF's neurotoxicity is still quite scarce. • This study reveals for the first time the interaction of MOFs with neural cells. - Abstract: Metal-organic frameworks (MOFs) possess unique properties desirable for delivery of drugs and gaseous therapeutics, but their uncharacterized interactions with cells raise increasing concerns of their safety in such biomedical applications. We evaluated the adverse effects of zinc nanoscale MOFs on the cell morphology, cytoskeleton, cell viability and expression of neurotrophin signaling pathway-associated GAP-43 protein in rat pheochromocytoma PC12 cells. At the concentration of 25 μg/ml, zinc MOFs did not significantly affect morphology, viability and membrane integrity of the cells. But at higher concentrations (over 100 μg/ml), MOFs exhibited a time- and concentration-dependent cytotoxicity, indicating their entry into the cells via endocytosis where they release Zn2+ into the cytosol to cause increased intracellular concentration of Zn2+. We demonstrated that the toxicity of MOFs was associated with a disrupted cellular zinc homeostasis and down-regulation of GAP-43 protein, which might be the underlying mechanism for the improved differentiation in PC12 cells. These findings highlight the importance of cytotoxic evaluation of the MOFs before their biomedical application

  8. Toxic effect of zinc nanoscale metal-organic frameworks on rat pheochromocytoma (PC12) cells in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Fei, E-mail: paper_mail@126.com [Department of Pharmacy, Nanfang Hospital, Southern Medical University, Guangzhou 510515 (China); Yang, Baochun; Cai, Jing [Department of Pharmacy, Nanfang Hospital, Southern Medical University, Guangzhou 510515 (China); Jiang, Yaodong [Department of Urology, Nanfang Hospital, Southern Medical University, Guangzhou 510515 (China); Xu, Jun [Department of Health Economy Administration, Nanfang Hospital, Southern Medical University, Guangzhou 510515 (China); Wang, Shan [Department of Pharmacy, Winthrop University Hospital, Mineola, NY 11501 (United States)

    2014-04-01

    Highlights: • Metal-organic frameworks (MOFs) represent a newborn family of hybrid materials. • MOFs have already shown promise in a number of biological applications. • The biological applications of MOFs raise concerns for potential cytotoxicity. • Substantial information about MOF's neurotoxicity is still quite scarce. • This study reveals for the first time the interaction of MOFs with neural cells. - Abstract: Metal-organic frameworks (MOFs) possess unique properties desirable for delivery of drugs and gaseous therapeutics, but their uncharacterized interactions with cells raise increasing concerns of their safety in such biomedical applications. We evaluated the adverse effects of zinc nanoscale MOFs on the cell morphology, cytoskeleton, cell viability and expression of neurotrophin signaling pathway-associated GAP-43 protein in rat pheochromocytoma PC12 cells. At the concentration of 25 μg/ml, zinc MOFs did not significantly affect morphology, viability and membrane integrity of the cells. But at higher concentrations (over 100 μg/ml), MOFs exhibited a time- and concentration-dependent cytotoxicity, indicating their entry into the cells via endocytosis where they release Zn{sup 2+} into the cytosol to cause increased intracellular concentration of Zn{sup 2+}. We demonstrated that the toxicity of MOFs was associated with a disrupted cellular zinc homeostasis and down-regulation of GAP-43 protein, which might be the underlying mechanism for the improved differentiation in PC12 cells. These findings highlight the importance of cytotoxic evaluation of the MOFs before their biomedical application.

  9. Diketopyrrolopyrrole Polymers for Organic Solar Cells.

    Science.gov (United States)

    Li, Weiwei; Hendriks, Koen H; Wienk, Martijn M; Janssen, René A J

    2016-01-19

    Conjugated polymers have been extensively studied for application in organic solar cells. In designing new polymers, particular attention has been given to tuning the absorption spectrum, molecular energy levels, crystallinity, and charge carrier mobility to enhance performance. As a result, the power conversion efficiencies (PCEs) of solar cells based on conjugated polymers as electron donor and fullerene derivatives as electron acceptor have exceeded 10% in single-junction and 11% in multijunction devices. Despite these efforts, it is notoriously difficult to establish thorough structure-property relationships that will be required to further optimize existing high-performance polymers to their intrinsic limits. In this Account, we highlight progress on the development and our understanding of diketopyrrolopyrrole (DPP) based conjugated polymers for polymer solar cells. The DPP moiety is strongly electron withdrawing and its polar nature enhances the tendency of DPP-based polymers to crystallize. As a result, DPP-based conjugated polymers often exhibit an advantageously broad and tunable optical absorption, up to 1000 nm, and high mobilities for holes and electrons, which can result in high photocurrents and good fill factors in solar cells. Here we focus on the structural modifications applied to DPP polymers and rationalize and explain the relationships between chemical structure and organic photovoltaic performance. The DPP polymers can be tuned via their aromatic substituents, their alkyl side chains, and the nature of the π-conjugated segment linking the units along the polymer chain. We show that these building blocks work together in determining the molecular conformation, the optical properties, the charge carrier mobility, and the solubility of the polymer. We identify the latter as a decisive parameter for DPP-based organic solar cells because it regulates the diameter of the semicrystalline DPP polymer fibers that form in the photovoltaic blends with

  10. Removal of the mechanoprotective influence of the cytoskeleton reveals PIEZO1 is gated by bilayer tension

    Science.gov (United States)

    Cox, Charles D.; Bae, Chilman; Ziegler, Lynn; Hartley, Silas; Nikolova-Krstevski, Vesna; Rohde, Paul R.; Ng, Chai-Ann; Sachs, Frederick; Gottlieb, Philip A.; Martinac, Boris

    2016-01-01

    Mechanosensitive ion channels are force-transducing enzymes that couple mechanical stimuli to ion flux. Understanding the gating mechanism of mechanosensitive channels is challenging because the stimulus seen by the channel reflects forces shared between the membrane, cytoskeleton and extracellular matrix. Here we examine whether the mechanosensitive channel PIEZO1 is activated by force-transmission through the bilayer. To achieve this, we generate HEK293 cell membrane blebs largely free of cytoskeleton. Using the bacterial channel MscL, we calibrate the bilayer tension demonstrating that activation of MscL in blebs is identical to that in reconstituted bilayers. Utilizing a novel PIEZO1-GFP fusion, we then show PIEZO1 is activated by bilayer tension in bleb membranes, gating at lower pressures indicative of removal of the cortical cytoskeleton and the mechanoprotection it provides. Thus, PIEZO1 channels must sense force directly transmitted through the bilayer.

  11. Optical Management Techniques for Organic Solar Cells

    CERN Document Server

    Rajagopal, Adharsh

    2016-01-01

    In this thesis, two different optical management techniques for organics based solar cells are explored. The first part is focused on the development of a textured rear reflector for OPVs. The use of textured reflector (TR) facilitates an increase in the optical path length along with light trapping within the active layer. TR was fabricated through a relatively simpler technique by depositing metal films over a microlens array (MLA). Zinc oxide nanoparticles were used to minimize the shadowing effect. Using TR, enhancements in short-circuit current density and power conversion efficiencies up to 10-25% were demonstrated for a polymer based organic solar cell. The second part is focused on improving the effectiveness of MLA incorporation in OPVs. The increase in path length achieved using MLA can be improved by increasing the refractive index of MLA and incorporating MLA directly on the transparent electrode instead of glass substrate. This approach could avoid the optical losses occurring at the interface be...

  12. Cardiac Electromechanical Models: From Cell to Organ

    Directory of Open Access Journals (Sweden)

    Natalia A Trayanova

    2011-08-01

    Full Text Available The heart is a multiphysics and multiscale system that has driven the development of the most sophisticated mathematical models at the frontiers of computation physiology and medicine. This review focuses on electromechanical (EM models of the heart from the molecular level of myofilaments to anatomical models of the organ. Because of the coupling in terms of function and emergent behaviors at each level of biological hierarchy, separation of behaviors at a given scale is difficult. Here, a separation is drawn at the cell level so that the first half addresses subcellular/single cell models and the second half addresses organ models. At the subcelluar level, myofilament models represent actin-myosin interaction and Ca-based activation. Myofilament models and their refinements represent an overview of the development in the field. The discussion of specific models emphasizes the roles of cooperative mechanisms and sarcomere length dependence of contraction force, considered the cellular basis of the Frank-Starling law. A model of electrophysiology and Ca handling can be coupled to a myofilament model to produce an EM cell model, and representative examples are summarized to provide an overview of the progression of field. The second half of the review covers organ-level models that require solution of the electrical component as a reaction-diffusion system and the mechanical component, in which active tension generated by the myocytes produces deformation of the organ as described by the equations of continuum mechanics. As outlined in the review, different organ-level models have chosen to use different ionic and myofilament models depending on the specific application; this choice has been largely dictated by compromises between model complexity and computational tractability. The review also addresses application areas of EM models such as cardiac resynchronization therapy and the role of mechano-electric coupling in arrhythmias and

  13. Innate lymphoid cells in secondary lymphoid organs.

    Science.gov (United States)

    Bar-Ephraïm, Yotam E; Mebius, Reina E

    2016-05-01

    The family of innate lymphoid cells (ILCs) has attracted attention in recent years as its members are important regulators of immunity, while they can also cause pathology. In both mouse and man, ILCs were initially discovered in developing lymph nodes as lymphoid tissue inducer (LTi) cells. These cells form the prototypic members of the ILC family and play a central role in the formation of secondary lymphoid organs (SLOs). In the absence of LTi cells, lymph nodes (LN) and Peyer's Patches (PP) fail to form in mice, although the splenic white pulp can develop normally. Besides LTi cells, the ILC family encompasses helper-like ILCs with functional distinctions as seen by T-helper cells, as well as cytotoxic natural killer (NK) cells. ILCs are still present in adult SLOs where they have been shown to play a role in lymphoid tissue regeneration. Furthermore, ILCs were implicated to interact with adaptive lymphocytes and influence the adaptive immune response. Here, we review the recent literature on the role of ILCs in secondary lymphoid tissue from the formation of SLOs to mature SLOs in adults, during homeostasis and pathology. PMID:27088915

  14. Solar cells on the base of organic semiconductors

    International Nuclear Information System (INIS)

    The parameters of organic solar cells on the base of different organic semiconductors as poly epoxypropyl carbazole, copper phthalocyanine and bordeaux perylene are considered. Moreover the properties of solar cells on the base of n-GaAs and copper phthalocyanine heterostructure are described. The new technologies in the field of organic solar cells as bulk heterostructure solar cells are discussed. (author)

  15. Nucleosome Organization in Human Embryonic Stem Cells.

    Directory of Open Access Journals (Sweden)

    Puya G Yazdi

    Full Text Available The fundamental repeating unit of eukaryotic chromatin is the nucleosome. Besides being involved in packaging DNA, nucleosome organization plays an important role in transcriptional regulation and cellular identity. Currently, there is much debate about the major determinants of the nucleosome architecture of a genome and its significance with little being known about its role in stem cells. To address these questions, we performed ultra-deep sequencing of nucleosomal DNA in two human embryonic stem cell lines and integrated our data with numerous epigenomic maps. Our analyses have revealed that the genome is a determinant of nucleosome organization with transcriptionally inactive regions characterized by a "ground state" of nucleosome profiles driven by underlying DNA sequences. DNA sequence preferences are associated with heterogeneous chromatin organization around transcription start sites. Transcription, histone modifications, and DNA methylation alter this "ground state" by having distinct effects on both nucleosome positioning and occupancy. As the transcriptional rate increases, nucleosomes become better positioned. Exons transcribed and included in the final spliced mRNA have distinct nucleosome profiles in comparison to exons not included at exon-exon junctions. Genes marked by the active modification H3K4m3 are characterized by lower nucleosome occupancy before the transcription start site compared to genes marked by the inactive modification H3K27m3, while bivalent domains, genes associated with both marks, lie exactly in the middle. Combinatorial patterns of epigenetic marks (chromatin states are associated with unique nucleosome profiles. Nucleosome organization varies around transcription factor binding in enhancers versus promoters. DNA methylation is associated with increasing nucleosome occupancy and different types of methylations have distinct location preferences within the nucleosome core particle. Finally, computational

  16. Tuning the material-cytoskeleton crosstalk via nanoconfinement of focal adhesions.

    Science.gov (United States)

    Natale, Carlo F; Ventre, Maurizio; Netti, Paolo A

    2014-03-01

    Material features proved to exert a potent influence on cell behaviour in terms of adhesion, migration and differentiation. In particular, biophysical and biochemical signals on material surfaces are able to affect focal adhesion distribution and cytoskeletal assemblies, which are known to regulate signalling pathways that ultimately influence cell fate and functions. However, a general, unifying model that correlates cytoskeletal-generated forces with genetic events has yet to be developed. Therefore, it is crucial to gain a better insight into the material-cytoskeleton crosstalk in order to design and fabricate biomaterials able to govern cell fate more accurately. In this work, we demonstrate that confining focal adhesion distribution and growth dramatically alters the cytoskeleton's structures and dynamics, which in turn dictate cellular and nuclear shape and polarization. MC3T3 preosteoblasts were cultivated on nanograted polydimethylsiloxane substrates and a thorough quantification - in static and dynamic modes - of the morphological and structural features of focal adhesions and cytoskeleton was performed. Nanoengineered surfaces provided well-defined zones for focal adhesions to form and grow. Unique cytoskeletal structures spontaneously assembled when focal adhesions were confined and, in fact, they proved to be very effective in deforming the nuclei. The results here presented provide elements to engineer surfaces apt to guide and control cell behaviour through the material-cytoskeleton-nucleus axis. PMID:24388800

  17. The contribution of cytoskeleton networks to stretch is strain dependent

    Science.gov (United States)

    Nnetu, Kenechukwu David; Kießling, Tobias; Stange, Roland; Käs, Josef

    2011-03-01

    The interaction between the cytoskeleton filaments in a cell provides it with mechanical stability and enables it to remodel its shape. The rheological response of cells has been characterized either as viscoelastic or soft-glassy which neglects the molecular origin of cell response. In this work, by using a large amount of cells (>10,000 in total) exceeding previous statistics by a decade, we link observed cell response to its molecular origin by showing that actin and microtubule networks maintain the mechanical integrity of cells in a strain dependent manner. While the actin network solely regulated cell deformation at small strain, the microtubule network was responsible for cell relaxation. At large strain, actin and microtubule networks dominated cell response with microtubules having a bipolar effect on cells upon stabilization. This effect could explain the relapse of some cancer after chemotherapy treatment using Taxol thus providing a bridge between soft condense matter physics and systems biology. This work was supported by the ESF-BuildMoNa and Exprimage (funded by the German Federal Ministry of Education and Research (BMBF)).

  18. Less is more: removing membrane attachments stiffens the RBC cytoskeleton

    Science.gov (United States)

    Gov, Nir S.

    2007-11-01

    The polymerized network of the cytoskeleton of the red-blood cell (RBC) contains different protein components that maintain its overall integrity and attachment to the lipid bilayer. One of these key components is the band 3-ankyrin complex that attaches the spectrin filaments to the fluid bilayer. Defects in this particular component result in the shape transformation called spherocytosis, through the shedding of membrane nano-vesicles. We show here that this transition and membrane shedding can be explained through the increased stiffness of the network when the band 3-ankyrin complexes are removed. ATP-induced transient dissociations lead to network softening, which offsets the stiffening to some extent, and causes increased fragility of these mutant cells, as is observed.

  19. Less is more: removing membrane attachments stiffens the RBC cytoskeleton

    Energy Technology Data Exchange (ETDEWEB)

    Gov, Nir S [Department of Chemical Physics, The Weizmann Institute of Science, PO Box 26, Rehovot 76100 (Israel)

    2007-11-15

    The polymerized network of the cytoskeleton of the red-blood cell (RBC) contains different protein components that maintain its overall integrity and attachment to the lipid bilayer. One of these key components is the band 3-ankyrin complex that attaches the spectrin filaments to the fluid bilayer. Defects in this particular component result in the shape transformation called spherocytosis, through the shedding of membrane nano-vesicles. We show here that this transition and membrane shedding can be explained through the increased stiffness of the network when the band 3-ankyrin complexes are removed. ATP-induced transient dissociations lead to network softening, which offsets the stiffening to some extent, and causes increased fragility of these mutant cells, as is observed.

  20. Hyperosmotic stress regulates the distribution and stability of myocardin-related transcription factor, a key modulator of the cytoskeleton

    DEFF Research Database (Denmark)

    Ly, Donald L.; Waheed, Faiza; Lodyga, Monika; Speight, Pam; Masszi, András; Nakano, Hiroyasu; Hersom, Maria Nathalie Selch; Pedersen, Stine Helene Falsig; Szászi, Katalin; Kapus, András

    2013-01-01

    Hyperosmotic stress initiates several adaptive responses, including the remodeling of the cytoskeleton. Besides maintaining structural integrity, the cytoskeleton has emerged as an important regulator of gene transcription. Myocardin-related transcription factor (MRTF), an actin-regulated coactiv......Hyperosmotic stress initiates several adaptive responses, including the remodeling of the cytoskeleton. Besides maintaining structural integrity, the cytoskeleton has emerged as an important regulator of gene transcription. Myocardin-related transcription factor (MRTF), an actin......-dependent transcription through the cis-element CArG box. Silencing or pharmacological inhibition of MRTF prevents the osmotic stimulation of CArG-dependent transcription and renders the cells susceptible to osmotic shock-induced structural damage. Interestingly, strong hyperosmolarity promotes proteasomal degradation of...

  1. Exploring the Possible Role of Lysine Acetylation on Entamoeba histolytica Virulence: A Focus on the Dynamics of the Actin Cytoskeleton

    Directory of Open Access Journals (Sweden)

    L. López-Contreras

    2013-01-01

    Full Text Available Cytoskeleton remodeling can be regulated, among other mechanisms, by lysine acetylation. The role of acetylation on cytoskeletal and other proteins of Entamoeba histolytica has been poorly studied. Dynamic rearrangements of the actin cytoskeleton are crucial for amebic motility and capping formation, processes that may be effective means of evading the host immune response. Here we report the possible effect of acetylation on the actin cytoskeleton dynamics and in vivo virulence of E. histolytica. Using western blot, immunoprecipitation, microscopy assays, and in silico analysis, we show results that strongly suggest that the increase in Aspirin-induced cytoplasm proteins acetylation reduced cell movement and capping formation, likely as a consequence of alterations in the structuration of the actin cytoskeleton. Additionally, intrahepatic inoculation of Aspirin-treated trophozoites in hamsters resulted in severe impairment of the amebic virulence. Taken together, these results suggest an important role for lysine acetylation in amebic invasiveness and virulence.

  2. Microtubule Disruption in Keratinocytes Induces Cell-Cell Adhesion through Activation of Endogenous E-Cadherin

    OpenAIRE

    Kee, Sun-Ho; Steinert, Peter M.

    2001-01-01

    The association of the cytoskeleton with the cadherin–catenin complex is essential for strong cell-cell adhesion in epithelial cells. In this study, we have investigated the effect of microtubule organization on cell-cell adhesion in differentiating keratinocytes. When microtubules of normal human epidermal keratinocytes (NHEKs) grown in low calcium media (0.05 mM) were disrupted with nocodazole or colcemid, cell-cell adhesion was induced through relocalization of the ...

  3. [Organs, tissues, and cells donation in Mexico].

    Science.gov (United States)

    Moreno-Treviño, María Guadalupe; Rivera-Silva, Gerardo

    2015-01-01

    Transplants are one of the most important advances of modern medicine; in the last 50 years in our country there have been more than fifty thousand transplants, which makes it clear that this is one of the most sought-after medical practices not only in Mexico but worldwide. In life, it is possible for a person to donate a kidney, a lung or a liver segment. When brain death occurs it is possible for a person to donate kidneys, heart, liver, pancreas, intestines, lungs, blood, hematopoietic cells, bone marrow, bones, corneas, heart valves, tendons, and arteries. However, the culture of organ donation is not widespread among Mexicans, hence in our country there is not even 50 % of the number of donations recommended by WHO, which impacts the number of patients who are waiting for an organ or tissue, which causes many of them die before receiving them. PMID:26506496

  4. Nanoparticles and nanoimaging for organic solar cells

    DEFF Research Database (Denmark)

    Pedersen, Emil Bøje Lind

    Solar energy is one of the few energy sources with the potential to power humanity in a future scenario where fossil fuels are not attractive due to their effect on the global climate or fossil fuels have been depleted all together. Organic photovoltaics is a promising technology for solar...... in photoactive Landfester nanoparticles. The dispersed particles are characterized by size, internal structure and crystallinity. Crystal orientation and spatial distribution of materials are quantified for cast layers of Landfester particles. A layer of particles is also investigated in a tandem solar cell...

  5. The role of cytoskeleton and adhesion proteins in the resistance to photodynamic therapy. Possible therapeutic interventions.

    Science.gov (United States)

    Di Venosa, Gabriela; Perotti, Christian; Batlle, Alcira; Casas, Adriana

    2015-08-01

    It is known that Photodynamic Therapy (PDT) induces changes in the cytoskeleton, the cell shape, and the adhesion properties of tumour cells. In addition, these targets have also been demonstrated to be involved in the development of PDT resistance. The reversal of PDT resistance by manipulating the cell adhesion process to substrata has been out of reach. Even though the existence of cell adhesion-mediated PDT resistance has not been reported so far, it cannot be ruled out. In addition to its impact on the apoptotic response to photodamage, the cytoskeleton alterations are thought to be associated with the processes of metastasis and invasion after PDT. In this review, we will address the impact of photodamage on the microfilament and microtubule cytoskeleton components and its regulators on PDT-treated cells as well as on cell adhesion. We will also summarise the impact of PDT on the surviving and resistant cells and their metastatic potential. Possible strategies aimed at taking advantage of the changes induced by PDT on actin, tubulin and cell adhesion proteins by targeting these molecules will also be discussed. PMID:25832889

  6. The Drosophila Anion Exchanger (DAE lacks a detectable interaction with the spectrin cytoskeleton

    Directory of Open Access Journals (Sweden)

    Base Christine

    2010-06-01

    Full Text Available Abstract Background Current models suggest that the spectrin cytoskeleton stabilizes interacting ion transport proteins at the plasma membrane. The human erythrocyte anion exchanger (AE1 was the first membrane transport protein found to be associated with the spectrin cytoskeleton. Here we evaluated a conserved anion exchanger from Drosophila (DAE as a marker for studies of the downstream effects of spectrin cytoskeleton mutations. Results Sequence comparisons established that DAE belongs to the SLC4A1-3 subfamily of anion exchangers that includes human AE1. Striking sequence conservation was observed in the C-terminal membrane transport domain and parts of the N-terminal cytoplasmic domain, but not in the proposed ankyrin-binding site. Using an antibody raised against DAE and a recombinant transgene expressed in Drosophila S2 cells DAE was shown to be a 136 kd plasma membrane protein. A major site of expression was found in the stomach acid-secreting region of the larval midgut. DAE codistributed with an infolded subcompartment of the basal plasma membrane of interstitial cells. However, spectrin did not codistribute with DAE at this site or in anterior midgut cells that abundantly expressed both spectrin and DAE. Ubiquitous knockdown of DAE with dsRNA eliminated antibody staining and was lethal, indicating that DAE is an essential gene product in Drosophila. Conclusions Based on the lack of colocalization and the lack of sequence conservation at the ankyrin-binding site, it appears that the well-characterized interaction between AE1 and the spectrin cytoskeleton in erythrocytes is not conserved in Drosophila. The results establish a pattern in which most of the known interactions between the spectrin cytoskeleton and the plasma membrane in mammals do not appear to be conserved in Drosophila.

  7. 不同压力的二氧化碳气腹对胃癌细胞迁移运动和细胞骨架的影响%Effects of different CO2 pressure pneumoperitoneum on the migration and cytoskeleton in gastric cancer cells

    Institute of Scientific and Technical Information of China (English)

    郝迎学; 钟华; 张超; 钱锋; 饶芸; 余佩武

    2008-01-01

    Objective To investigate the influence of CO2 and He insufflation administered at different pressures on the migration and cytoskeleton of cultured human gastric cancer coils.Methods The cultured gastric cancer cells MKN-45 were exposed to a CO2 or He environment maintained at different pressures (12,15 nun Hg).After 0,2,4,6,8 hours exposure to CO2 or He environment, pH of the MKN-45 cells culture media was measured with blood gas analysis. The cell migration was detected with Trauswell technology. The cell cytoskeleton was observed with laser eonfocal microscope. Results The media pH was acid after exposure to CO2 environment, while it was basic in the He group.The number of cells passing millipore in 12 mm Hg CO2 or He insufflation pressure were not significantly different with control group (P>0.05),however in 15 mm Hg pressure CO2 group,it was significantly decreased as compared to control group (P<0.01).The microfilament and microtubule in gastric cancer cell were ambiguous in 15 mm Hg pressure CO2 group.Conclusions There are no obvious effects on the migration and cytoskeleton of MKN-45 cells under 12 mm Hg CO2 insufflation pressure.The migration and cytoskeleton of MKN-45 cells can be inhibited in 15 mmHg CO2 pneumoperitoneum environment.%目的 通过体外模拟气腹环境,观察不同压力CO2或He(helium)对胃癌细胞MKN-45迁移运动和细胞骨架的影响.方法 将MKN-45细胞置于充满CO2或He的密闭培养箱中,按模拟气腹种类不同分为对照组、CO2气腹组和He气腹组,模拟气腹压力分别为12 mm Hg和15 mm Hg,作用时间均为4 h.于处理结束后即刻用血气分析仪检测培养液pH值;Transwell法观察细胞迁移运动变化;激光共聚焦显微镜观察细胞骨架变化.结果 CO2组细胞培养液呈酸性,He组细胞培养液呈碱性.CO2组和He组在12 mm Hg压力下MKN-45细胞穿过滤膜的数量较对照组差异无统计学意义(P>0.05).CO215 mm Hg组细胞穿过滤膜的数

  8. Eavesdropping on the cytoskeleton: progress and controversy in the yeast morphogenesis checkpoint.

    Science.gov (United States)

    Keaton, Mignon A; Lew, Daniel J

    2006-12-01

    The morphogenesis checkpoint provides a link between bud formation and mitosis in yeast. In this pathway, insults affecting the actin or septin cytoskeleton trigger a cell cycle arrest, mediated by the Wee1 homolog Swe1p, which catalyzes the inhibitory phosphorylation of the mitosis-promoting cyclin-dependent kinase (CDK) on a conserved tyrosine residue. Analyses of Swe1p phosphorylation have mapped 61 sites targeted by CDKs and Polo-related kinases, which control both Swe1p activity and Swe1p degradation. Although the sites themselves are not evolutionarily conserved, the control of Swe1p degradation exhibits many conserved features, and is linked to DNA-responsive checkpoints in vertebrate cells. At the 'sensing' end of the checkpoint, recent work has begun to shed light on how septins are organized and how they impact Swe1p regulators. However, the means by which Swe1p responds to actin perturbations once a bud has formed remains controversial. PMID:17055334

  9. Area-scaling of organic solar cells

    Science.gov (United States)

    Choi, Seungkeun; Potscavage, William J.; Kippelen, Bernard

    2009-09-01

    We report on the performance of organic solar cells based on pentacene/C60 heterojunctions as a function of active area. Devices with areas of 0.13 and 7 cm2 were fabricated on indium-tin-oxide (ITO) coated glass. Degradation of the performance with increased area is observed and analyzed in terms of the power loss density concept. The various power loss contributions to the total series resistance (RSA) are measured independently and compared to the values of the series resistance extracted from the current-voltage characteristics using a Shockley equivalent circuit model. The limited sheet resistance of ITO is found to be one of the major limiting factors when the area of the cell is increased. To reduce the effects of series resistance, thick, electroplated, metal grid electrodes were integrated with ITO in large-area cells. The metal grids were fabricated directly onto ITO and passivated with an insulator to prevent electrical shorts during the deposition of the top Al electrode. By integrating metal grids onto ITO, the series resistance could be reduced significantly yielding improved performance. Design guidelines for metal grids are described and tradeoffs are discussed.

  10. Involvement of the actin cytoskeleton and p21rho-family GTPases in the pathogenesis of the human protozoan parasite Entamoeba histolytica

    Directory of Open Access Journals (Sweden)

    G.D. Godbold

    1998-08-01

    Full Text Available It has been estimated that infection with the enteric protozoan parasite Entamoeba histolytica kills more than 50,000 people a year. Central to the pathogenesis of this organism is its ability to directly lyse host cells and cause tissue destruction. Amebic lesions show evidence of cell lysis, tissue necrosis, and damage to the extracellular matrix. The specific molecular mechanisms by which these events are initiated, transmitted, and effected are just beginning to be uncovered. In this article we review what is known about host cell adherence and contact-dependent cytolysis. We cover the involvement of the actin cytoskeleton and small GTP-binding proteins of the p21rho-family in the process of cell killing and phagocytosis, and also look at how amebic interactions with molecules of the extracellular matrix contribute to its cytopathic effects.

  11. Oscillatory fluid flow elicits changes in morphology, cytoskeleton and integrin-associated molecules in MLO-Y4 cells, but not in MC3T3-E1 cells.

    Science.gov (United States)

    Xu, Huiyun; Zhang, Jian; Wu, Jiawei; Guan, Ying; Weng, Yuanyuan; Shang, Peng

    2012-01-01

    Interstitial fluid flow stress is one of the most important mechanical stimulations of bone cells under physiological conditions. Osteocytes and osteoblasts act as primary mechanosensors within bones, and in vitro are able to respond to fluid shear stress, both morphologically and functionally. However, there is little information about the response of integrin-associated molecules using both osteoblasts and osteocytes. In this study, we investigated the changes in response to 2 hours of oscillatory fluid flow stress in the MLO-Y4 osteocyte-like cell line and the MC3T3-E1 osteoblast-like cell line. MLO-Y4 cells exhibited a significant increase in the expression of integrin-associated molecules, including OPN, CD44, vinculin and integrin αvβ3. However, there was no or limited increase observed in MC3T3-E1 osteoblast-like cells. Cell area and fiber stress formation were also markedly promoted by fluid flow only in MLO-Y4 cells. But the numbers of processes per cell remain unaffected in both cell lines. PMID:23096360

  12. Design and evaluation of Actichip, a thematic microarray for the study of the actin cytoskeleton

    Directory of Open Access Journals (Sweden)

    Chalmel Frédéric

    2007-08-01

    Full Text Available Abstract Background The actin cytoskeleton plays a crucial role in supporting and regulating numerous cellular processes. Mutations or alterations in the expression levels affecting the actin cytoskeleton system or related regulatory mechanisms are often associated with complex diseases such as cancer. Understanding how qualitative or quantitative changes in expression of the set of actin cytoskeleton genes are integrated to control actin dynamics and organisation is currently a challenge and should provide insights in identifying potential targets for drug discovery. Here we report the development of a dedicated microarray, the Actichip, containing 60-mer oligonucleotide probes for 327 genes selected for transcriptome analysis of the human actin cytoskeleton. Results Genomic data and sequence analysis features were retrieved from GenBank and stored in an integrative database called Actinome. From these data, probes were designed using a home-made program (CADO4MI allowing sequence refinement and improved probe specificity by combining the complementary information recovered from the UniGene and RefSeq databases. Actichip performance was analysed by hybridisation with RNAs extracted from epithelial MCF-7 cells and human skeletal muscle. Using thoroughly standardised procedures, we obtained microarray images with excellent quality resulting in high data reproducibility. Actichip displayed a large dynamic range extending over three logs with a limit of sensitivity between one and ten copies of transcript per cell. The array allowed accurate detection of small changes in gene expression and reliable classification of samples based on the expression profiles of tissue-specific genes. When compared to two other oligonucleotide microarray platforms, Actichip showed similar sensitivity and concordant expression ratios. Moreover, Actichip was able to discriminate the highly similar actin isoforms whereas the two other platforms did not. Conclusion Our

  13. Probing cytoskeleton dynamics by intracellular particle transport analysis

    Science.gov (United States)

    Götz, M.; Hodeck, K. F.; Witzel, P.; Nandi, A.; Lindner, B.; Heinrich, D.

    2015-07-01

    All cellular functions arise from the transport of molecules through a heterogeneous, highly dynamic cell interior for intracellular signaling. Here, the impact of intracellular architecture and cytoskeleton dynamics on transport processes is revealed by high-resolution single particle tracking within living cells, in combination with time-resolved local mean squared displacement (I-MSD) analysis. We apply the I-MSD analysis to trajectories of 200 nm silica particles within living cells of Dictyostelium discoideum obtained by high resolution spinning disc confocal microscopy with a frame rate of 100 fps and imaging in one fixed focal plane. We investigate phases of motor-driven active transport and subdiffusion, normal diffusion, as well as superdiffusion with high spatial and temporal resolution. Active directed intracellular motion is attributed to microtubule associated molecular motor driven transport with average absolute velocities of 2.8 μm s-1 for 200 nm diameter particles. Diffusion processes of these particles within wild-type cells are found to exhibit diffusion constants ranging across two orders of magnitude from subdiffusive to superdiffusive behavior. This type of analysis might prove of ample importance for medical applications, like targeted drug treatment of cells by nano-sized carriers or innovative diagnostic assays.

  14. Modified Equivalent Circuit for Organic Solar Cells

    Science.gov (United States)

    Hossain, Nazmul

    In this work a newly fabricated organic solar cell based on a composite of fullerene derivative [6,6]-phenyl-C61 butyric acid methyl ester (PCBM) and regioregular poly (3-hexylthiophene) (P3HT) with an added interfacial layer of AgOx in between the PEDOT:PSS layer and the ITO layer is investigated. Previous equivalent circuit models are discussed and an equivalent circuit model is proposed for the fabricated device. Incorporation of the AgOx interfacial layer shows an increase in fill factor (by 33%) and power conversion efficiency (by 28%). Moreover proper correlation has been achieved between the experimental and simulated I-V plots. The simulation shows that device characteristics can be explained with accuracy by the proposed model.

  15. Charge separation in organic photovoltaic cells

    CERN Document Server

    Giazitzidis, Paraskevas; Bisquert, Juan; Vikhrenko, Vyacheslav S

    2014-01-01

    We consider a simple model for the geminate electron-hole separation process in organic photovoltaicssss cells, in order to illustrate the influence of dimensionality of conducting channels on the efficiency of the process. The Miller-Abrahams expression for the transition rates between nearest neighbor sites was used for simulating random walks of the electron in the Coulomb field of the hole. The non-equilibrium kinetic Monte Carlo simulation results qualitatively confirm the equilibrium estimations, although quantitatively the efficiency of the higher dimensional systems is less pronounced. The lifetime of the electron prior to recombination is approximately equal to the lifetime prior to dissociation. Their values indicate that electrons perform long stochastic walks before they are captured by the collector or recombined. The non-equilibrium free energy considerably differs from the equilibrium one. The efficiency of the separation process decreases with increasing the distance to the collector, and this...

  16. Nanotomography of organic heterojunction solar cells

    International Nuclear Information System (INIS)

    The morphology of organic heterojunction solar cells based on blends of P3HT and PCBM is an important factor determining the power conversion efficiency. For a good charge carrier generation the interface between the two components should be as large as possible. Furthermore, bicontinuous networks of both components are required for an efficient charge carrier extraction. We investigate the three-dimensional structure of blends of P3HT and PCBM with Nanotomography based on scanning force microscopy (SPM). The specimen is ablated layer by layer using plasma etching and imaged with tapping mode SPM after each etching step. From the resulting series of images the three-dimensional structure is reconstructed. We will present first volume images of P3HT:PCBM blends and discuss the structure of the interface between donor and acceptor components in view of the charge generation efficiency.

  17. Association of Adenovirus with the Microtubule Organizing Center

    OpenAIRE

    Bailey, Christopher J.; Crystal, Ronald G.; Leopold, Philip L.

    2003-01-01

    Adenoviruses (Ad) must deliver their genomes to the nucleus of the target cell to initiate an infection. Following entry into the cell and escape from the endosome, Ad traffics along the microtubule cytoskeleton toward the nucleus. In the final step in Ad trafficking, Ad must leave the microtubule and establish an association with the nuclear envelope. We hypothesized that in cells lacking a nucleus, the capsid moves to and associates with the microtubule organizing center (MTOC). To test thi...

  18. TWISTED DWARF1 Mediates the Action of Auxin Transport Inhibitors on Actin Cytoskeleton Dynamics.

    Science.gov (United States)

    Zhu, Jinsheng; Bailly, Aurelien; Zwiewka, Marta; Sovero, Valpuri; Di Donato, Martin; Ge, Pei; Oehri, Jacqueline; Aryal, Bibek; Hao, Pengchao; Linnert, Miriam; Burgardt, Noelia Inés; Lücke, Christian; Weiwad, Matthias; Michel, Max; Weiergräber, Oliver H; Pollmann, Stephan; Azzarello, Elisa; Mancuso, Stefano; Ferro, Noel; Fukao, Yoichiro; Hoffmann, Céline; Wedlich-Söldner, Roland; Friml, Jiří; Thomas, Clément; Geisler, Markus

    2016-04-01

    Plant growth and architecture is regulated by the polar distribution of the hormone auxin. Polarity and flexibility of this process is provided by constant cycling of auxin transporter vesicles along actin filaments, coordinated by a positive auxin-actin feedback loop. Both polar auxin transport and vesicle cycling are inhibited by synthetic auxin transport inhibitors, such as 1-N-naphthylphthalamic acid (NPA), counteracting the effect of auxin; however, underlying targets and mechanisms are unclear. Using NMR, we map the NPA binding surface on the Arabidopsis thaliana ABCB chaperone TWISTED DWARF1 (TWD1). We identify ACTIN7 as a relevant, although likely indirect, TWD1 interactor, and show TWD1-dependent regulation of actin filament organization and dynamics and that TWD1 is required for NPA-mediated actin cytoskeleton remodeling. The TWD1-ACTIN7 axis controls plasma membrane presence of efflux transporters, and as a consequence act7 and twd1 share developmental and physiological phenotypes indicative of defects in auxin transport. These can be phenocopied by NPA treatment or by chemical actin (de)stabilization. We provide evidence that TWD1 determines downstream locations of auxin efflux transporters by adjusting actin filament debundling and dynamizing processes and mediating NPA action on the latter. This function appears to be evolutionary conserved since TWD1 expression in budding yeast alters actin polarization and cell polarity and provides NPA sensitivity. PMID:27053424

  19. Identification of Dynamic Changes in Proteins Associated with the Cellular Cytoskeleton after Exposure to Okadaic Acid

    Directory of Open Access Journals (Sweden)

    Peter Roepstorff

    2013-05-01

    Full Text Available Exposure of cells to the diarrhetic shellfish poison, okadaic acid, leads to a dramatic reorganization of cytoskeletal architecture and loss of cell-cell contact. When cells are exposed to high concentrations of okadaic acid (100–500 nM, the morphological rearrangement is followed by apoptotic cell death. Okadaic acid inhibits the broad acting Ser/Thr protein phosphatases 1 and 2A, which results in hyperphosphorylation of a large number of proteins. Some of these hyperphosphorylated proteins are most likely key players in the reorganization of the cell morphology induced by okadaic acid. We wanted to identify these phosphoproteins and searched for them in the cellular lipid rafts, which have been found to contain proteins that regulate cytoskeletal dynamics and cell adhesion. By using stable isotope labeling by amino acids in cell culture cells treated with okadaic acid (400 nM could be combined with control cells before the isolation of lipid rafts. Protein phosphorylation events and translocations induced by okadaic acid were identified by mass spectrometry. Okadaic acid was shown to regulate the phosphorylation status and location of proteins associated with the actin cytoskeleton, microtubules and cell adhesion structures. A large number of these okadaic acid-regulated proteins have previously also been shown to be similarly regulated prior to cell proliferation and migration. Our results suggest that okadaic acid activates general cell signaling pathways that induce breakdown of the cortical actin cytoskeleton and cell detachment.

  20. Light trapping in thin film organic solar cells

    Directory of Open Access Journals (Sweden)

    Zheng Tang

    2014-10-01

    Full Text Available A major issue in organic solar cells is the poor mobility and recombination of the photogenerated charge carriers. The active layer has to be kept thin to facilitate charge transport and minimize recombination losses. However, optical losses due to inefficient light absorption in the thin active layers can be considerable in organic solar cells. Therefore, light trapping schemes are critically important for efficient organic solar cells. Traditional light trapping schemes for thick solar cells need to be modified for organic thin film solar cells in which coherent optics and wave effects play a significant role. In this review, we discuss the light trapping schemes for organic thin film solar cells, which includes geometric engineering of the structure of the solar cell at the micro and nanoscale, plasmonic structures, and more.

  1. Decohesion Kinetics in Polymer Organic Solar Cells

    KAUST Repository

    Bruner, Christopher

    2014-12-10

    © 2014 American Chemical Society. We investigate the role of molecular weight (MW) of the photoactive polymer poly(3-hexylthiophene) (P3HT) on the temperature-dependent decohesion kinetics of bulk heterojunction (BHJ) organic solar cells (OSCs). The MW of P3HT has been directly correlated to its carrier field effect mobilities and the ambient temperature also affects OSC in-service performance and P3HT arrangement within the BHJ layer. Under inert conditions, time-dependent decohesion readily occurs within the BHJ layer at loads well below its fracture resistance. We observe that by increasing the MW of P3HT, greater resistance to decohesion is achieved. However, failure consistently occurs within the BHJ layer representing the weakest layer within the device stack. Additionally, it was found that at temperatures below the glass transition temperature (∼41-45 °C), decohesion was characterized by brittle failure via molecular bond rupture. Above the glass transition temperature, decohesion growth occurred by a viscoelastic process in the BHJ layer, leading to a significant degree of viscoelastic deformation. We develop a viscoelastic model based on molecular relaxation to describe the resulting behavior. The study has implications for OSC long-term reliability and device performance, which are important for OSC production and implementation.

  2. A comparative study of the effect of oxidative stress on the cytoskeleton in human cortical neurons

    International Nuclear Information System (INIS)

    Cytoskeleton disruption is a process by which oxidative stress disrupts cellular function. This study compares and contrasts the effect of oxidative stress on the three major cytoskeleton filaments, microfilaments (MFs), microtubule (MT), and vimentin in human cortical neuronal cell line (HCN2). HCN2 cells were treated with 100 μM tertiary butylhydroperoxide (t-BuOOH), a free radical generating neurotoxin for 1, 3, or 6 h. Cell viability studies demonstrated significant cell death although the morphology studies showed that there was a substantial loss in neurites of neurons treated with t-BuOOH for 6 h. Because the cytoskeleton plays a role in neurite outgrowth, the effect of oxidative stress on the cytoskeletal was studied. In neurons subjected to oxidative stress for 30 min or 1 h, there were no major changes in microfilament distribution though there was altered distribution of microtubule and vimentin filaments as compared to controls. However, loss and disruption of all the three cytoskeletal filaments was observed at later times (3 and 6 h), which was confirmed by Western Blot analysis. Further studies were done to measure the gene expression levels of actin, tubulin, and vimentin. Results indicated that the overall loss of the cytoskeletal proteins in neurons treated with free radical generating toxin might not be a direct result of the downregulation of the cytoskeletal genes. This study shows that free radical generation in human neurons leads to the disruption of the cytoskeleton, though there may be a difference in the susceptibility to oxidative stress among the individual components of the cytoskeletal filaments

  3. Distribution of epinemin in colloidal gold-labelled, quick-frozen, deep- etched cytoskeletons

    OpenAIRE

    1984-01-01

    In this study I describe the ultrastructural distribution of epinemin (Lawson, D., 1983, J. Cell Biol., 97:1891-1905) in antibody-labelled, helium-cooled, quick-frozen, deep-etched cytoskeletons. This technique reveals that epinemin is expressed asymmetrically at discrete sites on the vimentin core polymer and that usually one (occasionally two or three) antiepinemin molecules are found at each of these discrete foci. Single receptor-bound antiepinemin (IgM) molecules are easily identified in...

  4. The microtubule cytoskeleton does not integrate auxin transport and gravitropism in maize roots

    Science.gov (United States)

    Hasenstein, K. H.; Blancaflor, E. B.; Lee, J. S.

    1999-01-01

    The Cholodny-Went hypothesis of gravitropism suggests that the graviresponse is controlled by the distribution of auxin. However, the mechanism of auxin transport during the graviresponse of roots is still unresolved. To determine whether the microtubule (MT) cytoskeleton is participating in auxin transport, the cytoskeleton was examined and the movement of 3H-IAA measured in intact and excised taxol, oryzalin, and naphthylphthalamic acid (NPA)-treated roots of Zea mays cv. Merit. Taxol and oryzalin did not inhibit the graviresponse of roots but the auxin transport inhibitor NPA greatly inhibited both auxin transport and graviresponse. NPA had no effect on MT organization in vertical roots, but caused MT reorientation in horizontally placed roots. Regardless of treatment, the organization of MTs in intact roots differed from that in root segments. The MT inhibitors, taxol and oryzalin had opposite effects on the MTs, namely, depolymerization (oryzalin) and stabilization and thickening (taxol), but both treatments caused swelling of the roots. The data indicate that the MT cytoskeleton does not directly interfere with auxin transport or auxin-mediated growth responses in maize roots.

  5. Adhesion in flexible organic and hybrid organic/inorganic light emitting device and solar cells

    International Nuclear Information System (INIS)

    This paper presents the results of an experimental study of the adhesion between bi-material pairs that are relevant to organic light emitting devices, hybrid organic/inorganic light emitting devices, organic bulk heterojunction solar cells, and hybrid organic/inorganic solar cells on flexible substrates. Adhesion between the possible bi-material pairs is measured using force microscopy (AFM) techniques. These include: interfaces that are relevant to organic light emitting devices, hybrid organic/inorganic light emitting devices, bulk heterojunction solar cells, and hybrid combinations of titanium dioxide (TiO2) and poly(3-hexylthiophene). The results of AFM measurements are incorporated into the Derjaguin-Muller-Toporov model for the determination of adhesion energies. The implications of the results are then discussed for the design of robust organic and hybrid organic/inorganic electronic devices

  6. Large Scale Computer Simulation of Erythrocyte Membranes with Explicit Cytoskeleton^

    Science.gov (United States)

    Harvey, Cameron; Revalee, Joel; Laradji, Mohamed; Kumar, P. B. Sunil

    2008-03-01

    The erythrocyte membrane is composed essentially of a self-assembled lipid bilayer and a polymerized protein meshwork, referred to as the cytoskeleton. For the erythrocyte, the polymer meshwork is composed of spectrin and anchored to the bilayer through specialized proteins. In this investigation we extended a coarse-grained model of self-assembled lipid membranes, recently developed by us, to account for the cytoskeleton. Simulation of bilayer patches, with dimensions about 0.5 μm x 0.5 μm, were performed^ to investigate the effects of the cytoskeleton on the membrane elastic properties. The bending modulus and surface tension are extracted from the spectra of the out-of-plane thermal undulations of the membrane. Using Monte Carlo, we also extracted the compression and shear moduli. Preliminary findings suggest a measurable effect in thermal undulations resulting from the introduction of the cytoskeleton.

  7. Pathways to a New Efficiency Regime for Organic Solar Cells

    NARCIS (Netherlands)

    Koster, L. Jan Anton; Shaheen, Sean E.; Hummelen, Jan C.

    2012-01-01

    Three different theoretical approaches are presented to identify pathways to organic solar cells with power conversion efficiencies in excess of 20%. A radiation limit for organic solar cells is introduced that elucidates the role of charge-transfer (CT) state absorption. Provided this CT action is

  8. Organic solar cells theory, experiment, and device simulation

    CERN Document Server

    Tress, Wolfgang

    2014-01-01

    This book covers in a textbook-like fashion the basics or organic solar cells, addressing the limits of photovoltaic energy conversion and giving a well-illustrated introduction to molecular electronics with focus on the working principle and characterization of organic solar cells. Further chapters based on the author's dissertation focus on the electrical processes in organic solar cells by presenting a detailed drift-diffusion approach to describe exciton separation and charge-carrier transport and extraction. The results, although elaborated on small-molecule solar cells and with focus on

  9. Global phosphoproteome profiling reveals unanticipated networks responsive to cisplatin treatment of embryonic stem cells

    DEFF Research Database (Denmark)

    Pines, Alex; Kelstrup, Christian D; Vrouwe, Mischa G;

    2011-01-01

    (stable isotope labeling by amino acids in cell culture)-labeled murine embryonic stem cells with the anticancer drug cisplatin. Network and pathway analyses indicated that processes related to the DNA damage response and cytoskeleton organization were significantly affected. Although the ATM (ataxia...

  10. Aging changes in organs - tissue - cells

    Science.gov (United States)

    ... lose some function as you age during adulthood. Aging changes occur in all of the body's cells, ... and peripheral nerves are made of nerve tissue. AGING CHANGES Cells are the basic building blocks of ...

  11. Temperature response of the neuronal cytoskeleton mapped via atomic force and fluorescence microscopy

    CERN Document Server

    Spedden, Elise; Staii, Cristian

    2013-01-01

    Neuronal cells change their growth properties in response to external physical stimuli such as variations in external temperature, stiffness of the growth substrate, or topographical guidance cues. Detailed knowledge of the mechanisms that control these biomechanical responses is necessary for understanding the basic principles that underlie neuronal growth and regeneration. Here, we present elasticity maps of living cortical neurons (embryonic rat) as a function of temperature, and correlate these maps to the locations of internal structural components of the cytoskeleton. Neurons display a significant increase in the average elastic modulus upon a decrease in ambient temperature from 37{\\deg}C to 25{\\deg}C. We demonstrate that the dominant mechanism by which the elasticity of the neurons changes in response to temperature is the stiffening of the actin components of the cytoskeleton induced by myosin II. We also report a reversible shift in the location and composition of the high-stiffness areas of the neu...

  12. Effect of collagen I and fibronectin on the adhesion, elasticity and cytoskeletal organization of prostate cancer cells

    International Nuclear Information System (INIS)

    Research highlights: → Depending on the metastatic origin, prostate cancer cells differ in their affinity to COL1. → COL1 affects specifically the F-actin and cell elasticity of bone-derived prostate cancer cells. → Cell elasticity can be used as a biomarker for cancer cells from different metastases. -- Abstract: Despite of intensive research efforts, the precise mechanism of prostate cancer metastasis in bone is still not fully understood. Several studies have suggested that specific matrix production by the bone cells, such as collagen I, supports cancer cell invasion. The aim of this study was to investigate the effect of collagen I (COL1) and fibronectin (FN) on cell adhesion, cell elasticity and cytoskeletal organization of prostate cancer cells. Two cell lines, bone marrow- (PC3) and lymph node-derived (LNCaP) were cultivated on COL1 and FN (control protein). By using a quantitative adhesion assay and time-lapse analysis, it was found that PC3, but not LNCaP, adhered strongly and were more spread on COL1. Next, PC3 and LNCaP were evaluated by atomic force microscopy (AFM) and flatness shape factor and cellular Young's modulus were calculated. The shape analysis revealed that PC3 were significantly flatter when grown on COL1 in comparison to LNCaP. In general, PC3 were also significantly stiffer than LNCaP and furthermore, their stiffness increased upon interaction with COL1. Since cell stiffness is strongly dependent on actin organization, phalloidin-based actin staining was performed and revealed that, of the two cell types as well as the two different matrix proteins, only PC3 grown on COL1 formed robust actin cytoskeleton. In conclusion, our study showed that PC3 cells have a strong affinity towards COL1. On this matrix protein, the cells adhered strongly and underwent a specific cell flattening. Moreover, with the establishment of PC3 contact to COL1 a significant increase of PC3 stiffness was observed due to a profound cytoskeletal rearrangement.

  13. Interfering with the connection between the nucleus and the cytoskeleton affects nuclear rotation, mechanotransduction and myogenesis.

    Science.gov (United States)

    Brosig, Michaela; Ferralli, Jacqueline; Gelman, Laurent; Chiquet, Matthias; Chiquet-Ehrismann, Ruth

    2010-10-01

    Mechanical stress controls a broad range of cellular functions. The cytoskeleton is physically connected to the extracellular matrix via integrin receptors, and to the nuclear lamina by the LINC complex that spans both nuclear membranes. We asked here how disruption of this direct link from the cytoskeleton to nuclear chromatin affects mechanotransduction. Fibroblasts grown on flexible silicone membranes reacted to cyclic stretch by nuclear rotation. This rotation was abolished by inhibition of actomyosin contraction as well as by overexpression of dominant-negative versions of nesprin or sun proteins that form the LINC complex. In an in vitro model of muscle differentiation, cyclic strain inhibits differentiation and induces proliferation of C2C12 myoblasts. Interference with the LINC complex in these cells abrogated their stretch-induced proliferation, while stretch increased p38 MAPK and NFkappaB phosphorylation and the transcript levels of myogenic transcription factors MyoD and myogenin. We found that the physical link from the cytoskeleton to the nuclear lamina is crucial for correct mechanotransduction, and that disruption of the LINC complex perturbs the mechanical control of cell differentiation. PMID:20621196

  14. Hypotonicity and cell volume regulation in shark rectal gland: role of organic osmolytes and F-actin.

    Science.gov (United States)

    Ziyadeh, F N; Mills, J W; Kleinzeller, A

    1992-03-01

    Hypotonic stress (reduction of external tonicity from approximately 900 mosM and 295 mM NaCl to approximately 600 mosM and 135 mM NaCl) produced a relatively slow regulatory volume decrease (RVD) in dogfish shark (Squalus acanthias) rectal gland cells. During the 5-h experiment, cell K+ content remained unchanged; cell content of Na+ and Cl- dropped in the initial swelling phase by some 50% (reflecting the corresponding reduction in medium NaCl), and then remained unchanged during volume recovery phase. Also, cellular fluxes of 86Rb+ and urea were not affected by hypotonic stress. However, hypotonicity enhanced 10- to 20-fold the efflux of organic cell osmolytes taurine, betaine, and trimethyloxamine, and this accounted for the loss of osmotically obliged water during RVD. Enhancement of osmolyte efflux by hypotonic stress was abolished by readjusting the low-Na+ saline to isotonicity (approximately 900 mosM) with innocuous cations (choline+, Li+, or N-methylglucamine+). The results suggest that reduction of medium tonicity may be the determinant for the RVD response to hypotonic stress. The above properties of the observed RVD were also displayed when studying changes on cell F-actin at the basolateral cell face; hypotonic stress (medium with 135 mM NaCl) produced a rapid disappearance of fluorescence related to this cytoskeletal component, whereas no such changes were seen in low-Na+ salines made isotonic with choline or N-methylglucamine chloride nor in a saline made hyposmolar by omitting urea. Hence, hypotonicity is required to affect F-actin organization (depolymerization?). These changes of F-actin fluorescence are transient; they were completed within 5-10 min of hypotonic stress, and afterwards a gradual reconstitution of cell F-actin organization was seen. The above observations are consistent with the assumption that, in shark rectal gland cells, transient loss of cytoskeleton (F-actin) organization at the basolateral cell face, induced by hypotonicity

  15. Nanoscale cell membrane organization : a near-field optical view

    OpenAIRE

    Koopman, Marjolein

    2006-01-01

    The cell plasma membrane of eukaryotic cells is a lipid bi-layer that separates the cell cytosol from the extracellular environment. The composition and organization of proteins and lipids within this bi-layer have a direct impact on many cellular processes, since they form the senses of the cell. Technological advances, like high resolution microscopy together with the possibility to address different membrane components via specific labeling now allows researchers to investigate cell membra...

  16. Nanoscale dimples for improved absorption in organic solar cells

    DEFF Research Database (Denmark)

    Goszczak, Arkadiusz Jaroslaw; Rubahn, Horst-Günter; Madsen, Morten

    Organic solar cells (OSC’s) have attracted much attention in the past years due to their potential low-cost, light-weight and mechanical flexibility. A method for improving the power conversion efficiencies of the devices is by incorporating structured electrodes in the solar cell architecture...... ordered and discorded dimple arrangement and their contribution to light management is presented. Such dimples can later be employed to fabricate nanostructured electrodes in P3HT/PCBM organic solar cells....

  17. Organic photovoltaic cells utilizing ultrathin sensitizing layer

    Science.gov (United States)

    Rand, Barry P.; Forrest, Stephen R.

    2011-05-24

    A photosensitive device includes a series of organic photoactive layers disposed between two electrodes. Each layer in the series is in direct contact with a next layer in the series. The series is arranged to form at least one donor-acceptor heterojunction, and includes a first organic photoactive layer comprising a first host material serving as a donor, a thin second organic photoactive layer comprising a second host material disposed between the first and a third organic photoactive layer, and the third organic photoactive layer comprising a third host material serving as an acceptor. The first, second, and third host materials are different. The thin second layer serves as an acceptor relative to the first layer or as a donor relative to the third layer.

  18. Epstein-Barr virus LMP1 modulates lipid raft microdomains and the vimentin cytoskeleton for signal transduction and transformation.

    Science.gov (United States)

    Meckes, David G; Menaker, Nathan F; Raab-Traub, Nancy

    2013-02-01

    The Epstein-Barr virus (EBV) is an important human pathogen that is associated with multiple cancers. The major oncoprotein of the virus, latent membrane protein 1 (LMP1), is essential for EBV B-cell immortalization and is sufficient to transform rodent fibroblasts. This viral transmembrane protein activates multiple cellular signaling pathways by engaging critical effector molecules and thus acts as a ligand-independent growth factor receptor. LMP1 is thought to signal from internal lipid raft containing membranes; however, the mechanisms through which these events occur remain largely unknown. Lipid rafts are microdomains within membranes that are rich in cholesterol and sphingolipids. Lipid rafts act as organization centers for biological processes, including signal transduction, protein trafficking, and pathogen entry and egress. In this study, the recruitment of key signaling components to lipid raft microdomains by LMP1 was analyzed. LMP1 increased the localization of phosphatidylinositol 3-kinase (PI3K) and its activated downstream target, Akt, to lipid rafts. In addition, mass spectrometry analyses identified elevated vimentin in rafts isolated from LMP1 expressing NPC cells. Disruption of lipid rafts through cholesterol depletion inhibited PI3K localization to membranes and decreased both Akt and ERK activation. Reduction of vimentin levels or disruption of its organization also decreased LMP1-mediated Akt and ERK activation and inhibited transformation of rodent fibroblasts. These findings indicate that LMP1 reorganizes membrane and cytoskeleton microdomains to modulate signal transduction. PMID:23152522

  19. Simulation of Organic Solar Cells Using AMPS-1D Program

    Directory of Open Access Journals (Sweden)

    Samah G. Babiker

    2012-03-01

    Full Text Available The analysis of microelectronic and photonic structure in one dimension program [AMPS-1D] program has been successfully used to study inorganic solar cells. In this work the program has been used to optimize the performance of the organic solar cells. The cells considered consist of poly(2-methoxy-5-(3,7- dimethyloctyloxy-1,4-phenylenevinylene [MDMO-PPV

  20. The Architectural Organization of Human Stem Cell Cycle Regulatory Machinery

    OpenAIRE

    Stein, Gary S.; Stein, Janet L.; van Wijnen, Andre J.; Lian, Jane B.; Montecino, Martin; Medina, Ricardo(Instituto de Matemática e Computação, Universidade Federal de Itajubá, Itajubá, Minas Gerais, Brazil); Kapinas, Kristie; Ghule, Prachi; Grandy, Rodrigo; Zaidi, Sayyed K.; Becker, Klaus A.

    2012-01-01

    Two striking features of human embryonic stem cells that support biological activity are an abbreviated cell cycle and reduced complexity to nuclear organization. The potential implications for rapid proliferation of human embryonic stem cells within the context of sustaining pluripotency, suppressing phenotypic gene expression and linkage to simplicity in the architectural compartmentalization of regulatory machinery in nuclear microenvironments is explored. Characterization of the molecular...

  1. Assembly of cells and vesicles for organ engineering

    International Nuclear Information System (INIS)

    The development of materials and technologies for the assembly of cells and/or vesicles is a key for the next generation of tissue engineering. Since the introduction of the tissue engineering concept in 1993, various types of scaffolds have been developed for the regeneration of connective tissues in vitro and in vivo. Cartilage, bone and skin have been successfully regenerated in vitro, and these regenerated tissues have been applied clinically. However, organs such as the liver and pancreas constitute numerous cell types, contain small amounts of extracellular matrix, and are highly vascularized. Therefore, organ engineering will require the assembly of cells and/or vesicles. In particular, adhesion between cells/vesicles will be required for regeneration of organs in vitro. This review introduces and discusses the key technologies and materials for the assembly of cells/vesicles for organ regeneration. (topical review)

  2. Assembly of cells and vesicles for organ engineering

    Directory of Open Access Journals (Sweden)

    Tetsushi Taguchi

    2011-01-01

    Full Text Available The development of materials and technologies for the assembly of cells and/or vesicles is a key for the next generation of tissue engineering. Since the introduction of the tissue engineering concept in 1993, various types of scaffolds have been developed for the regeneration of connective tissues in vitro and in vivo. Cartilage, bone and skin have been successfully regenerated in vitro, and these regenerated tissues have been applied clinically. However, organs such as the liver and pancreas constitute numerous cell types, contain small amounts of extracellular matrix, and are highly vascularized. Therefore, organ engineering will require the assembly of cells and/or vesicles. In particular, adhesion between cells/vesicles will be required for regeneration of organs in vitro. This review introduces and discusses the key technologies and materials for the assembly of cells/vesicles for organ regeneration.

  3. Assembly of cells and vesicles for organ engineering

    Energy Technology Data Exchange (ETDEWEB)

    Taguchi, Tetsushi, E-mail: taguchi.tetsushi@nims.go.jp [Biofunctional Materials Unit, Nano-Bio Field, Materials Nanoarchitectonics (MANA), National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

    2011-12-15

    The development of materials and technologies for the assembly of cells and/or vesicles is a key for the next generation of tissue engineering. Since the introduction of the tissue engineering concept in 1993, various types of scaffolds have been developed for the regeneration of connective tissues in vitro and in vivo. Cartilage, bone and skin have been successfully regenerated in vitro, and these regenerated tissues have been applied clinically. However, organs such as the liver and pancreas constitute numerous cell types, contain small amounts of extracellular matrix, and are highly vascularized. Therefore, organ engineering will require the assembly of cells and/or vesicles. In particular, adhesion between cells/vesicles will be required for regeneration of organs in vitro. This review introduces and discusses the key technologies and materials for the assembly of cells/vesicles for organ regeneration. (topical review)

  4. Assembly of cells and vesicles for organ engineering

    Science.gov (United States)

    Taguchi, Tetsushi

    2011-12-01

    The development of materials and technologies for the assembly of cells and/or vesicles is a key for the next generation of tissue engineering. Since the introduction of the tissue engineering concept in 1993, various types of scaffolds have been developed for the regeneration of connective tissues in vitro and in vivo. Cartilage, bone and skin have been successfully regenerated in vitro, and these regenerated tissues have been applied clinically. However, organs such as the liver and pancreas constitute numerous cell types, contain small amounts of extracellular matrix, and are highly vascularized. Therefore, organ engineering will require the assembly of cells and/or vesicles. In particular, adhesion between cells/vesicles will be required for regeneration of organs in vitro. This review introduces and discusses the key technologies and materials for the assembly of cells/vesicles for organ regeneration.

  5. Stability and degradation mechanisms in organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Ecker, Bernhard

    2012-04-26

    This thesis deals with stability improvements and the investigation of degradation mechanisms in organic solar cells. Organic solar cells have been in the focus of extensive academic research for over almost two decades and are currently entering the market in small scale applications. For successful large scale applications, next to the improvement of the power conversion efficiency, the stability of organic solar cells has to be increased. This thesis is dedicated to the investigation of novel materials and architectures to study stability-related issues and degradation mechanisms in order to contribute to the basic understanding of the working principles of organic solar cells. Here, impedance spectroscopy, a frequency domain technique, is used to gain information about stability and degradation mechanisms in organic solar cells. In combination with systematic variations in the preparation of solar cells, impedance spectroscopy gives the possibility to differentiate between interface and bulk dominated effects. Additionally, impedance spectroscopy gives access to the dielectric properties of the device, such as capacitance. This offers among other things the opportunity to probe the charge carrier concentration and the density of states. Another powerful way of evaluation is the combination of experimentally obtained impedance spectra with equivalent circuit modelling. The thesis presents results on novel materials and solar cell architectures for efficient hole and electron extraction. This indicates the importance of knowledge over interlayers and interfaces for improving both the efficiency and stability of organic solar cells.

  6. Fundamental investigations on periodic nano- and microstructured organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Niggemann, M.

    2005-03-15

    Using organic semiconducting materials in solar cells is a new approach with promising possibilities. The great potential of low cost production combined with mechanical flexibility gives rise to new applications. Due to the relatively simple fabrication process from solution and the mechanical flexibility, the production of organic solar cells by the cost effective roll-to-roll process appears promising. However, the preconditions for commercialization are not fulfilled as yet. The demands on organic solar cells strongly depend on the type of application. The highest demands on solar cell technologies are set by the energy market. Organic solar cells are only expected to be competitive on the energy market when the requirements on efficiency, lifetime and costs are fulfilled at the same time. Regarding this as a long term goal, a less demanding but still challenging medium term goal would be the application of relatively small organic solar cell modules for i.e. portable electronic devices. The integration of Organic Field Effect Transistors (OFET) and Organic Light Emitting Diodes (OLED) to all-polymer electronic devices is still under development. Nevertheless, the integration of organic solar cells as one functional component appears promising as the production technologies are expected to be compatible. The innovative contribution of this thesis to the development of organic solar cells is as follows: Motivated by the desire to fabricate efficient and cost effective organic solar cells, the approach of developing novel solar cell architectures based on periodic nano- and microstructures is followed. At present, planar organic solar cells with indium tin oxide (ITO) as a transparent electrode are intensively studied. One decisive cost factor would, however, be the indium price, which is the key component of the ITO electrode. The planar cell architecture can be conceived as a one-dimensional photonic device, however the presented work widens the investigations

  7. Cytoskeleton and Golgi-apparatus interactions: a two-way road of function and structure

    Directory of Open Access Journals (Sweden)

    Egea G

    2015-01-01

    Full Text Available Gustavo Egea,1 Carla Serra-Peinado,1 María P Gavilan,2 Rosa M Rios21Departament de Biologia Cel·lular, Immulogia i Neurociències, Facultat de Medicina and Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS, Universitat de Barcelona, Barcelona, Spain; 2Departamento de Señalización Celular, CSIC-Centro Andaluz de Biomedicina y Medicina Regenerativa (CABIMER, Seville, SpainAbstract: The Golgi apparatus is the result of a complex and dynamic interaction between a large variety of molecules that determine its architecture, protein and lipid transports, and those that integrate signals from outside and inside the cell. The cytoskeleton facilitates the functional integration of all these processes. Association and coordination between microtubules and actin filaments, as well as their respective binding and regulatory proteins, are clearly necessary for Golgi structure and function. Protein sorting, membrane fission and fusion, and the motion of Golgi-derived transport carriers are all affected by both cytoskeleton elements.Keywords: cytoskeleton, Golgi apparatus, membrane trafficking, secretory pathway, actin, microtubules

  8. Pathogenesis of common glomerular diseases – role of the podocyte cytoskeleton

    Directory of Open Access Journals (Sweden)

    Kumagai T

    2012-10-01

    Full Text Available Takanori Kumagai, Flaviana Mouawad, Tomoko TakanoDepartment of Medicine, McGill University Health Centre, Montreal, Quebec, CanadaAbstract: Glomerulus is the filtration unit of the kidney where the first step of urine formation takes place. In the glomerulus, water and small molecules including waste products of the body are filtered into the urine, while large molecules essential for body function such as albumin are retained. When this barrier function of the kidney is impaired, protein leakage into the urine (proteinuria occurs. Proteinuria is not only a hallmark of many glomerular diseases but also a prognostic marker of kidney disease progression. Visceral glomerular epithelial cells (commonly called podocytes are known to have an important role in the maintenance of glomerular barrier function. In the last decade, remarkable progress has been made in podocyte biology, mainly led by the discoveries of important proteins that work together to maintain the intricate morphology and function of podocytes. Most of these so-called podocyte proteins modulate the actin cytoskeleton either directly or indirectly. The aim of the current review is to discuss the pathogenesis of common glomerular diseases with a particular focus on the role of the actin cytoskeleton in podocytes. The diseases covered include minimal change disease, focal segmental glomerulosclerosis (idiopathic and hereditary, membranous nephropathy, hypertensive glomerulosclerosis, and diabetic nephropathy.Keywords: glomerular disease, podocyte, cytoskeleton, proteinuria

  9. Soluble axoplasm enriched from injured CNS axons reveals the early modulation of the actin cytoskeleton.

    Directory of Open Access Journals (Sweden)

    Patrick Garland

    Full Text Available Axon injury and degeneration is a common consequence of diverse neurological conditions including multiple sclerosis, traumatic brain injury and spinal cord injury. The molecular events underlying axon degeneration are poorly understood. We have developed a novel method to enrich for axoplasm from rodent optic nerve and characterised the early events in Wallerian degeneration using an unbiased proteomics screen. Our detergent-free method draws axoplasm into a dehydrated hydrogel of the polymer poly(2-hydroxyethyl methacrylate, which is then recovered using centrifugation. This technique is able to recover axonal proteins and significantly deplete glial contamination as confirmed by immunoblotting. We have used iTRAQ to compare axoplasm-enriched samples from naïve vs injured optic nerves, which has revealed a pronounced modulation of proteins associated with the actin cytoskeleton. To confirm the modulation of the actin cytoskeleton in injured axons we focused on the RhoA pathway. Western blotting revealed an augmentation of RhoA and phosphorylated cofilin in axoplasm-enriched samples from injured optic nerve. To investigate the localisation of these components of the RhoA pathway in injured axons we transected axons of primary hippocampal neurons in vitro. We observed an early modulation of filamentous actin with a concomitant redistribution of phosphorylated cofilin in injured axons. At later time-points, RhoA is found to accumulate in axonal swellings and also colocalises with filamentous actin. The actin cytoskeleton is a known sensor of cell viability across multiple eukaryotes, and our results suggest a similar role for the actin cytoskeleton following axon injury. In agreement with other reports, our data also highlights the role of the RhoA pathway in axon degeneration. These findings highlight a previously unexplored area of axon biology, which may open novel avenues to prevent axon degeneration. Our method for isolating CNS axoplasm

  10. The Role of Actin Cytoskeleton in Memory Formation in Amygdala.

    Science.gov (United States)

    Lamprecht, Raphael

    2016-01-01

    The central, lateral and basolateral amygdala (BLA) nuclei are essential for the formation of long-term memories including emotional and drug-related memories. Studying cellular and molecular mechanisms of memory in amygdala may lead to better understanding of how memory is formed and of fear and addiction-related disorders. A challenge is to identify molecules activated by learning that subserve cellular changes needed for memory formation and maintenance in amygdala. Recent studies show that activation of synaptic receptors during fear and drug-related learning leads to alteration in actin cytoskeleton dynamics and structure in amygdala. Such changes in actin cytoskeleton in amygdala are essential for fear and drug-related memories formation. Moreover, the actin cytoskeleton subserves, after learning, changes in neuronal morphogenesis and glutamate receptors trafficking in amygdala. These cellular events are involved in fear and drug-related memories formation. Actin polymerization is also needed for the maintenance of drug-associated memories in amygdala. Thus, the actin cytoskeleton is a key mediator between receptor activation during learning and cellular changes subserving long-term memory (LTM) in amygdala. The actin cytoskeleton may serve as a target for pharmacological treatment of fear memory associated with fear and anxiety disorders and drug addiction to prevent the debilitating consequences of these diseases. PMID:27065800

  11. Organ or Stem Cell Transplant and Your Mouth

    Science.gov (United States)

    ... is less likely to develop problems. See Your Dentist Before Transplant Before an organ or stem cell ... important for your general health too. See Your Dentist After Transplant Make sure your dentist knows that ...

  12. Coupling of cytoskeleton functions for fibroblast locomotion

    DEFF Research Database (Denmark)

    Couchman, J R; Lenn, M; Rees, D A

    1985-01-01

    Using a chick cell phenotype specialised for locomotion with morphometric measurements made possible by modern instrumentation technology, we have reinvestigated motile functions in fibroblast locomotion. Quantitative analysis of rapid fluctuations in cell form and organelle distribution during l...... function of microtubules to direct the flow towards multiple foci on the leading edge, and so determine cell polarity. Such a mechanism of locomotion for fibroblasts has many features consistent with evidence for other cell types, especially amoebae and leukocytes....

  13. Genome organization, instabilities, stem cells, and cancer

    Directory of Open Access Journals (Sweden)

    Senthil Kumar Pazhanisamy

    2009-01-01

    Full Text Available It is now widely recognized that advances in exploring genome organization provide remarkable insights on the induction and progression of chromosome abnormalities. Much of what we know about how mutations evolve and consequently transform into genome instabilities has been characterized in the spatial organization context of chromatin. Nevertheless, many underlying concepts of impact of the chromatin organization on perpetuation of multiple mutations and on propagation of chromosomal aberrations remain to be investigated in detail. Genesis of genome instabilities from accumulation of multiple mutations that drive tumorigenesis is increasingly becoming a focal theme in cancer studies. This review focuses on structural alterations evolve to raise a variety of genome instabilities that are manifested at the nucleotide, gene or sub-chromosomal, and whole chromosome level of genome. Here we explore an underlying connection between genome instability and cancer in the light of genome architecture. This review is limited to studies directed towards spatial organizational aspects of origin and propagation of aberrations into genetically unstable tumors.

  14. Development of an organic redox couple and organic dyes for aqueous dye-sensitized solar cells

    OpenAIRE

    Tian, Haining; Gabrielsson, Erik; Lohse, Peter William; Vlachopoulos, Nick; Kloo, Lars; Hagfeldt, Anders; Sun, Licheng

    2012-01-01

    A water-soluble organic redox couple (TT-/DTT) and new organic dyes (D45 and D51) have been developed for aqueous dye-sensitized solar cells (DSCs). An optimal efficiency of 3.5% was obtained using the D51 dye and an optimized electrolyte composition. The highest IPCE value obtained was 68% at 460 nm. QC 20130108

  15. Advanced Glycation End Products Impair Glucose-Stimulated Insulin Secretion of a Pancreatic β-Cell Line INS-1-3 by Disturbance of Microtubule Cytoskeleton via p38/MAPK Activation

    Science.gov (United States)

    You, Jia; Xu, Shiqing; Zhang, Wenjian; Fang, Qing; Liu, Honglin; Peng, Liang; Deng, Tingting

    2016-01-01

    Advanced glycation end products (AGEs) are believed to be involved in diverse complications of diabetes mellitus. Overexposure to AGEs of pancreatic β-cells leads to decreased insulin secretion and cell apoptosis. Here, to understand the cytotoxicity of AGEs to pancreatic β-cells, we used INS-1-3 cells as a β-cell model to address this question, which was a subclone of INS-1 cells and exhibited high level of insulin expression and high sensitivity to glucose stimulation. Exposed to large dose of AGEs, even though more insulin was synthesized, its secretion was significantly reduced from INS-1-3 cells. Further, AGEs treatment led to a time-dependent increase of depolymerized microtubules, which was accompanied by an increase of activated p38/MAPK in INS-1-3 cells. Pharmacological inhibition of p38/MAPK by SB202190 reversed microtubule depolymerization to a stabilized polymerization status but could not rescue the reduction of insulin release caused by AGEs. Taken together, these results suggest a novel role of AGEs-induced impairment of insulin secretion, which is partially due to a disturbance of microtubule dynamics that resulted from an activation of the p38/MAPK pathway.

  16. The appropriateness of organic solar cells for indoor lighting conditions

    Science.gov (United States)

    Minnaert, B.; Veelaert, P.

    2010-05-01

    Most commercially available photovoltaic solar cells are crystalline silicon cells. However, in indoor environments, the efficiency of silicon solar cells is poor. Typically, the light intensity under artificial lighting conditions is less than 10 W/m2 as compared to 100-1000 W/m2 under outdoor conditions. Moreover, the spectrum is different from the outdoor solar spectrum and there is more diffuse than direct light. Taken into account the predicted cheaper costs for the production of organic solar cells, a possible niche market for organic PV can be indoor applications. In this article, we study the influence of the narrow absorption window, characteristic for organic solar cells, for different indoor conditions. This comparison is made for typical artificial light sources, i.e. a common incandescent lamp, an LED lamp and a "warm" and a "cool" fluorescent tube, which are compared to the outdoor AM 1.5 spectrum as reference. The comparisons are done by simulation based on the quantum efficiencies of the solar cells and the light spectra of the different light sources. A classical silicon solar cell is used as reference. In this way we determine the appropriateness for indoor use of organic solar cells.

  17. Orientational Order of the Lamellipodial Actin Network as Demonstrated in Living Motile CellsV⃞

    OpenAIRE

    Alexander B. Verkhovsky; Chaga, Oleg Y.; Schaub, Sébastien; Svitkina, Tatyana M.; Meister, Jean-Jacques; Borisy, Gary G.

    2003-01-01

    Lamellipodia of crawling cells represent both the motor for cell advance and the primary building site for the actin cytoskeleton. The organization of actin in the lamellipodium reflects actin dynamics and is of critical importance for the mechanism of cell motility. In previous structural studies, the lamellipodial actin network was analyzed primarily by electron microscopy (EM). An understanding of lamellipodial organization would benefit significantly if the EM data were complemented and p...

  18. Computer Simulation of Cytoskeleton-Induced Blebbing in Lipid Membranes

    CERN Document Server

    Spangler, Eric J; Revalee, Joel D; Kumar, P B Sunil; Laradji, Mohamed

    2011-01-01

    Blebs are balloon-shaped membrane protrusions that form during many physiological processes. Using computer simulation of a particle-based model for self-assembled lipid bilayers coupled to an elastic meshwork, we investigated the phase behavior and kinetics of blebbing. We found that blebs form for large values of the ratio between the areas of the bilayer and the cytoskeleton. We also found that blebbing can be induced when the cytoskeleton is subject to a localized ablation or a uniform compression. The results obtained are qualitatively in agreement with the experimental evidence and the model opens up the possibility to study the kinetics of bleb formation in detail.

  19. About the transparent electrode of the organic photovoltaic cells

    Science.gov (United States)

    Bernède, J.-C.; Nguyen, D.-T.; Cattin, L.; Morsli, M.; Kanth, S. R. B.; Patil, S.

    2011-12-01

    Electrodes and the nature of their contact with organic materials play a crucial role in the realization of efficient optoelectronic components. Whether the injection (organic light-emitting diodes - OLEDs) or collection (organic photovoltaic cells - OPV cells) of carriers, contacts must be as efficient as possible. To do this, it is customary to refer to electrode surface treatment and/or using a buffer layer all things to optimize the contact. Efficiency of organic photovoltaic cells based on organic electron donor/organic electron acceptor junctions can be strongly improved when the transparent conductive anode is coated with a buffer layer (ABL). We show that an ultra-thin gold (0.5 nm) or a thin molybdenum oxide (3-5 nm) can be used as efficient ABL. However, the effects of these ABL depend on the highest occupied molecular orbital (HOMO) of different electron donors of the OPV cells. The results indicate that, in the case of metal ABL, a good matching between the work function of the anode and the highest occupied molecular orbital of the donor material is the major factor limiting the hole transfer efficiency. Indeed, gold is efficient as ABL only when the HOMO of the organic donor is close to its work function ФAu. MoO3 has a wider field of application as ABL than gold. The role of the oxide is not so clearly understood than that of Au, different models proposed to interpret the experimental results are discussed.

  20. Interfacial processes in small molecule organic solar cells

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    This paper presents an overview of the recent progress of small molecule organic solar cells mainly based on the previous worksof our group. We will mainly focus on the interfacial processes in the cells. The dissociation of excitons at electrode/organic andorganic/organic interfaces can be directly observed by transient photovoltage measurements. A simple model including dissociationof excitons at the interface and drift of free carriers in the built-in field is proposed to explain the observed signals of transientphotovoltage. Besides exciton-blocking and preventing damage due to cathode evaporation,blocking permeation of oxygen and/orwater molecules and modulating the built-in field are proposed as functions of the buffer layer between C60 and Al. By the use ofthe inverted structure,a shelf lifetime of over 1500 h is achieved for unencapsulated small-molecule organic solar cells.

  1. Organic / IV, III-V Semiconductor Hybrid Solar Cells

    Directory of Open Access Journals (Sweden)

    Pang-Leen Ong

    2010-03-01

    Full Text Available We present a review of the emerging class of hybrid solar cells based on organic-semiconductor (Group IV, III-V, nanocomposites, which states separately from dye synthesized, polymer-metal oxides and organic-inorganic (Group II-VI nanocomposite photovoltaics. The structure of such hybrid cell comprises of an organic active material (p-type deposited by coating, printing or spraying technique on the surface of bulk or nanostructured semiconductor (n-type forming a heterojunction between the two materials. Organic components include various photosensitive monomers (e.g., phtalocyanines or porphyrines, conjugated polymers, and carbon nanotubes. Mechanisms of the charge separation at the interface and their transport are discussed. Also, perspectives on the future development of such hybrid cells and comparative analysis with other classes of photovoltaics of third generation are presented.

  2. Surviving protein quality control catastrophes--from cells to organisms.

    Science.gov (United States)

    Schneider, Kim; Bertolotti, Anne

    2015-11-01

    Organisms have evolved mechanisms to cope with and adapt to unexpected challenges and harsh conditions. Unfolded or misfolded proteins represent a threat for cells and organisms, and the deposition of misfolded proteins is a defining feature of many age-related human diseases, including the increasingly prevalent neurodegenerative diseases. These protein misfolding diseases are devastating and currently cannot be cured, but are hopefully not incurable. In fact, the aggregation-prone and potentially harmful proteins at the origins of protein misfolding diseases are expressed throughout life, whereas the diseases are late onset. This reveals that cells and organisms are normally resilient to disease-causing proteins and survive the threat of misfolded proteins up to a point. This Commentary will outline the limits of the cellular resilience to protein misfolding, and discuss the possibility of pushing these limits to help cells and organisms to survive the threat of misfolding proteins and to avoid protein quality control catastrophes. PMID:26483388

  3. Role of cytoskeleton in the mechanisms of stretch-induced cardiomyocytical hypertrophy in vitro

    Institute of Scientific and Technical Information of China (English)

    FENG Bing; QIN Jun; HE Zuo-yun; WANG De-wen

    2001-01-01

    To study in vitro the role of cytoskeleton in the mechanisms of stretch-induced cardiomyocyte hypertrophy. Methods: After cultured on a deformable membrane, the myocardial cells were incorporated with 3H-leucine (3H-leu) to determine the hypertrophic rate. The contents of angiotensin Ⅱ and endothelin in the supernatant of the culture medium were measured with radioimmunoassay. Results: Colchicine at 4 μmol/L partially inhibited 3H-leu incorporation rate of the stretch-induced cardiomyocytes but cytochalasin B showed no such effect. The radioactivity of 3H-leu incorporation in the supernatant of the culture medium was significantly lower in the cardiomyocyte culture treated with colchicines (4 μmol/L) or cytochalasin (0.4 μmol/L) than in simple myocardial cell culture. In addition, the 2 agents markedly inhibited the myocardial cells from secreting angiotensin Ⅱ and endothin. Conclusion: The cytoskeleton plays a role in the stretch-induced mycardiocyte hypertrophy by mediating the secretion of the cell growth factors by the cells themselves.

  4. The Change of Microtubule Cytoskeleton in the Stem-Tip Cells of Sugarcane during Mitosis%甘蔗茎尖细胞有丝分裂过程中微管骨架的变化

    Institute of Scientific and Technical Information of China (English)

    李志刚; 赵洪波; 李素丽; 杨丽涛; 李杨瑞

    2008-01-01

    In order to understand the microtubule change of monoeotyls stem-tip during mitosis,the arrangement,transformation of microtubule array and its relation with chromosome movement during mitosis were studied with freezing microtome,indirect immunofluorescence,DAPI staining and fluorescence microscopy.The results showed that nueleolus was intact when the cortical miemtubules formed;cortical mierotubulos were changed into phramoplast microtubule bands at mitosis prophase.When phramoplast microtubule came into being,nuclear membrane was ruptured and chromosome was arranged at the position of cell plate;subsequently,phramoplast microtubules were changed into phragmoplast mierotubules,phramoplast mierotubules were shortening and microtubules on the sides of cell plate were increasing gradually,during this course sister chromatid was separated by microtubules at cell plate and tract to the two poles,forming phragmoplast microtubules.Then the nucleolus of two daughter cells formed and separated in the end with the increase of cells numbers.Therefore,cell division orientation could be judged from the arrangement of cell microtubules in different periods in order to understand its growth status.

  5. Self-Organization in Disaster Resilient Heterogeneous Small Cell Networks

    OpenAIRE

    Zhang, Haijun; Jiang, Chunxiao; Hu, Rose Qingyang; Qian, Yi

    2015-01-01

    Heterogeneous small cell networks with overlay femtocells and macrocell is a promising solution for future heterogeneous wireless cellular communications. However, great resilience is needed in heterogeneous small cells in case of accidents, attacks and natural disasters. In this article, we first describe the network architecture of disaster resilient heterogeneous small cell networks (DRHSCNs), where several self-organization inspired approaches are applied. Based on the proposed resilient ...

  6. A numerical semiconductor model applicable to organic solar cells

    OpenAIRE

    Minnaert, Ben; Burgelman, Marc; Heereman, Frédéric

    2007-01-01

    Excitons are marginally important in classical semiconductor device physics, and their treatment is not included in standard solar cell modelling. However, in organic semiconductors and solar cells, the role of excitons is essential, as the primary effect of light absorption is exciton generation, and free electrons and holes are created by exciton dissociation. First steps to include excitons in solar cell modelling were presented by Green and Zhang. We extended their model (2006), includin...

  7. Organic Solar Cells Performances Improvement Induced by Interface Buffer Layers

    OpenAIRE

    Bernède, J. C.; Godoy, A.; Cattin, L; Diaz, F. R.; MORSLI, M; Valle, M. A. del

    2010-01-01

    In the last 22 years that have elapsed since the pioneering work of Tang [Tang, Appl. Phys. Lett., 1986], significant improvement in the fundamental understanding and cells construction have led to efficiencies higher than 6%. The new concept of polymer:fullerene BHJ solar cells has allowed dramatic improvements in devices efficiency. It has induced a healthy competition with the multi-heterojunction devices base on small organic molecules, which induces significant progress in both cells fam...

  8. Protein 4.1R binds to CLASP2 and regulates dynamics,organization and attachment of microtubules to the cell cortex

    NARCIS (Netherlands)

    A. Ruiz-Saenz (Ana); J. van Haren (Jeffrey); C.L. Sayas (C. Laura); L. Rangel (Laura); J.A.A. Demmers (Jeroen); J. Millán (Jaime); M.A. Alonso (Miguel); N.J. Galjart (Niels); J.M. Correas

    2013-01-01

    textabstractThe microtubule (MT) cytoskeleton is essential for many cellular processes, including cell polarity and migration. Cortical platforms, formed by a subset of MT plus-end-tracking proteins, such as CLASP2, and non-MT binding proteins such as LL5b, attach distal ends of MTs to the cell cort

  9. Rotational manipulation of single cells and organisms using acoustic waves.

    Science.gov (United States)

    Ahmed, Daniel; Ozcelik, Adem; Bojanala, Nagagireesh; Nama, Nitesh; Upadhyay, Awani; Chen, Yuchao; Hanna-Rose, Wendy; Huang, Tony Jun

    2016-01-01

    The precise rotational manipulation of single cells or organisms is invaluable to many applications in biology, chemistry, physics and medicine. In this article, we describe an acoustic-based, on-chip manipulation method that can rotate single microparticles, cells and organisms. To achieve this, we trapped microbubbles within predefined sidewall microcavities inside a microchannel. In an acoustic field, trapped microbubbles were driven into oscillatory motion generating steady microvortices which were utilized to precisely rotate colloids, cells and entire organisms (that is, C. elegans). We have tested the capabilities of our method by analysing reproductive system pathologies and nervous system morphology in C. elegans. Using our device, we revealed the underlying abnormal cell fusion causing defective vulval morphology in mutant worms. Our acoustofluidic rotational manipulation (ARM) technique is an easy-to-use, compact, and biocompatible method, permitting rotation regardless of optical, magnetic or electrical properties of the sample under investigation. PMID:27004764

  10. Rotational manipulation of single cells and organisms using acoustic waves

    Science.gov (United States)

    Ahmed, Daniel; Ozcelik, Adem; Bojanala, Nagagireesh; Nama, Nitesh; Upadhyay, Awani; Chen, Yuchao; Hanna-Rose, Wendy; Huang, Tony Jun

    2016-01-01

    The precise rotational manipulation of single cells or organisms is invaluable to many applications in biology, chemistry, physics and medicine. In this article, we describe an acoustic-based, on-chip manipulation method that can rotate single microparticles, cells and organisms. To achieve this, we trapped microbubbles within predefined sidewall microcavities inside a microchannel. In an acoustic field, trapped microbubbles were driven into oscillatory motion generating steady microvortices which were utilized to precisely rotate colloids, cells and entire organisms (that is, C. elegans). We have tested the capabilities of our method by analysing reproductive system pathologies and nervous system morphology in C. elegans. Using our device, we revealed the underlying abnormal cell fusion causing defective vulval morphology in mutant worms. Our acoustofluidic rotational manipulation (ARM) technique is an easy-to-use, compact, and biocompatible method, permitting rotation regardless of optical, magnetic or electrical properties of the sample under investigation. PMID:27004764

  11. Study of neural cells on organic semiconductor ultra thin films

    Energy Technology Data Exchange (ETDEWEB)

    Bystrenova, Eva; Tonazzini, Ilaria; Stoliar, Pablo; Greco, Pierpaolo; Lazar, Adina; Dutta, Soumya; Dionigi, Chiara; Cacace, Marcello; Biscarini, Fabio [ISMN-CNR, Bologna (Italy); Jelitai, Marta; Madarasz, Emilia [IEM- HAS, Budapest (Hungary); Huth, Martin; Nickel, Bert [LMU, Munich (Germany); Martini, Claudia [Dept. PNPB, Univ. of Pisa (Italy)

    2008-07-01

    Many technological advances are currently being developed for nano-fabrication, offering the ability to create and control patterns of soft materials. We report the deposition of cells on organic semiconductor ultra-thin films. This is a first step towards the development of active bio/non bio systems for electrical transduction. Thin films of pentacene, whose thickness was systematically varied, were grown by high vacuum sublimation. We report adhesion, growth, and differentiation of human astroglial cells and mouse neural stem cells on an organic semiconductor. Viability of astroglial cells in time was measured as a function of the roughness and the characteristic morphology of ultra thin organic film, as well as the features of the patterned molecules. Optical fluorescence microscope coupled to atomic force microscope was used to monitor the presence, density and shape of deposited cells. Neural stem cells remain viable, differentiate by retinoic acid and form dense neuronal networks. We have shown the possibility to integrate living neural cells on organic semiconductor thin films.

  12. The Power and the Promise of Cell Reprogramming: Personalized Autologous Body Organ and Cell Transplantation

    Directory of Open Access Journals (Sweden)

    Ana Belen Alvarez Palomo

    2014-04-01

    Full Text Available Reprogramming somatic cells to induced pluripotent stem cells (iPSCs or direct reprogramming to desired cell types are powerful and new in vitro methods for the study of human disease, cell replacement therapy, and drug development. Both methods to reprogram cells are unconstrained by the ethical and social questions raised by embryonic stem cells. iPSC technology promises to enable personalized autologous cell therapy and has the potential to revolutionize cell replacement therapy and regenerative medicine. Potential applications of iPSC technology are rapidly increasing in ambition from discrete cell replacement applications to the iPSC assisted bioengineering of body organs for personalized autologous body organ transplant. Recent work has demonstrated that the generation of organs from iPSCs is a future possibility. The development of embryonic-like organ structures bioengineered from iPSCs has been achieved, such as an early brain structure (cerebral organoids, bone, optic vesicle-like structures (eye, cardiac muscle tissue (heart, primitive pancreas islet cells, a tooth-like structure (teeth, and functional liver buds (liver. Thus, iPSC technology offers, in the future, the powerful and unique possibility to make body organs for transplantation removing the need for organ donation and immune suppressing drugs. Whilst it is clear that iPSCs are rapidly becoming the lead cell type for research into cell replacement therapy and body organ transplantation strategies in humans, it is not known whether (1 such transplants will stimulate host immune responses; and (2 whether this technology will be capable of the bioengineering of a complete and fully functional human organ. This review will not focus on reprogramming to iPSCs, of which a plethora of reviews can be found, but instead focus on the latest developments in direct reprogramming of cells, the bioengineering of body organs from iPSCs, and an analysis of the immune response induced by i

  13. Cell Motility

    CERN Document Server

    Lenz, Peter

    2008-01-01

    Cell motility is a fascinating example of cell behavior which is fundamentally important to a number of biological and pathological processes. It is based on a complex self-organized mechano-chemical machine consisting of cytoskeletal filaments and molecular motors. In general, the cytoskeleton is responsible for the movement of the entire cell and for movements within the cell. The main challenge in the field of cell motility is to develop a complete physical description on how and why cells move. For this purpose new ways of modeling the properties of biological cells have to be found. This long term goal can only be achieved if new experimental techniques are developed to extract physical information from these living systems and if theoretical models are found which bridge the gap between molecular and mesoscopic length scales. Cell Motility gives an authoritative overview of the fundamental biological facts, theoretical models, and current experimental developments in this fascinating area.

  14. Dielectric nanostructures for broadband light trapping in organic solar cells

    KAUST Repository

    Raman, Aaswath

    2011-09-15

    Organic bulk heterojunction solar cells are a promising candidate for low-cost next-generation photovoltaic systems. However, carrier extraction limitations necessitate thin active layers that sacrifice absorption for internal quantum efficiency or vice versa. Motivated by recent theoretical developments, we show that dielectric wavelength-scale grating structures can produce significant absorption resonances in a realistic organic cell architecture. We numerically demonstrate that 1D, 2D and multi-level ITO-air gratings lying on top of the organic solar cell stack produce a 8-15% increase in photocurrent for a model organic solar cell where PCDTBT:PC71BM is the organic semiconductor. Specific to this approach, the active layer itself remains untouched yet receives the benefit of light trapping by nanostructuring the top surface below which it lies. The techniques developed here are broadly applicable to organic semiconductors in general, and enable partial decoupling between active layer thickness and photocurrent generation. © 2011 Optical Society of America.

  15. Autophagy is required for ectoplasmic specialization assembly in sertoli cells.

    Science.gov (United States)

    Liu, Chao; Wang, Hongna; Shang, Yongliang; Liu, Weixiao; Song, Zhenhua; Zhao, Haichao; Wang, Lina; Jia, Pengfei; Gao, Fengyi; Xu, Zhiliang; Yang, Lin; Gao, Fei; Li, Wei

    2016-05-01

    The ectoplasmic specialization (ES) is essential for Sertoli-germ cell communication to support all phases of germ cell development and maturity. Its formation and remodeling requires rapid reorganization of the cytoskeleton. However, the molecular mechanism underlying the regulation of ES assembly is still largely unknown. Here, we show that Sertoli cell-specific disruption of autophagy influenced male mouse fertility due to the resulting disorganized seminiferous tubules and spermatozoa with malformed heads. In autophagy-deficient mouse testes, cytoskeleton structures were disordered and ES assembly was disrupted. The disorganization of the cytoskeleton structures might be caused by the accumulation of a negative cytoskeleton organization regulator, PDLIM1, and these defects could be partially rescued by Pdlim1 knockdown in autophagy-deficient Sertoli cells. Altogether, our works reveal that the degradation of PDLIM1 by autophagy in Sertoli cells is important for the proper assembly of the ES, and these findings define a novel role for autophagy in Sertoli cell-germ cell communication. PMID:26986811

  16. Neurofibromatosis type 2 protein co-localizes with elements of the cytoskeleton

    OpenAIRE

    Bakker, M.A.H.; Tascilar, M.; Riegman, P.H.J.; Hekman, A.C.P.; Boersma, W.; Janssen, P. J A; Jong, T.A.W. de; Hendriks, W.J.A.J.; Kwast, T. H.; Zwarthoff, E C

    1995-01-01

    The product of the neurofibromatosis type 2 (NF2) tumor suppressor gene is a 595-amino-acid protein bearing resemblance to a family of band-4.1-related proteins. These proteins, including ezrin, radixin, and moesin, probably function as molecular linking proteins, connecting the cytoskeleton to the cell membrane. On the grounds of the homology to the ezrin, radixin, and moesin proteins and on the basis of its predicted secondary structure, the NF2 protein is also thought to act as a cytoskele...

  17. Interconnection between actin cytoskeleton and plant defense signaling

    Czech Academy of Sciences Publication Activity Database

    Janda, Martin; Matoušková, J.; Burketová, Lenka; Valentová, O.

    2014-01-01

    Roč. 9, č. 11 (2014). ISSN 1559-2316 R&D Projects: GA ČR(CZ) GAP501/11/1654 Institutional support: RVO:61389030 Keywords : Actin * Cytoskeleton * Pathogen Subject RIV: ED - Physiology http://gateway.isiknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=Alerting&SrcApp=Alerting&DestApp=MEDLINE&DestLinkType=FullRecord&UT=25482795

  18. Fullerene derivatives as electron acceptors for organic photovoltaic cells.

    Science.gov (United States)

    Mi, Dongbo; Kim, Ji-Hoon; Kim, Hee Un; Xu, Fei; Hwang, Do-Hoon

    2014-02-01

    Energy is currently one of the most important problems humankind faces. Depletion of traditional energy sources such as coal and oil results in the need to develop new ways to create, transport, and store electricity. In this regard, the sun, which can be considered as a giant nuclear fusion reactor, represents the most powerful source of energy available in our solar system. For photovoltaic cells to gain widespread acceptance as a source of clean and renewable energy, the cost per watt of solar energy must be decreased. Organic photovoltaic cells, developed in the past two decades, have potential as alternatives to traditional inorganic semiconductor photovoltaic cells, which suffer from high environmental pollution and energy consumption during production. Organic photovoltaic cells are composed of a blended film of a conjugated-polymer donor and a soluble fullerene-derivative acceptor sandwiched between a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)-coated indium tin oxide positive electrode and a low-work-function metal negative electrode. Considerable research efforts aim at designing and synthesizing novel fullerene derivatives as electron acceptors with up-raised lowest unoccupied molecular orbital energy, better light-harvesting properties, higher electron mobility, and better miscibility with the polymer donor for improving the power conversion efficiency of the organic photovoltaic cells. In this paper, we systematically review novel fullerene acceptors synthesized through chemical modification for enhancing the photovoltaic performance by increasing open-circuit voltage, short-circuit current, and fill factor, which determine the performance of organic photovoltaic cells. PMID:24749413

  19. Adaptation to optimal cell growth through self-organized criticality.

    Science.gov (United States)

    Furusawa, Chikara; Kaneko, Kunihiko

    2012-05-18

    A simple cell model consisting of a catalytic reaction network is studied to show that cellular states are self-organized in a critical state for achieving optimal growth; we consider the catalytic network dynamics over a wide range of environmental conditions, through the spontaneous regulation of nutrient transport into the cell. Furthermore, we find that the adaptability of cellular growth to reach a critical state depends only on the extent of environmental changes, while all chemical species in the cell exhibit correlated partial adaptation. These results are in remarkable agreement with the recent experimental observations of the present cells. PMID:23003193

  20. High-resolution three-dimensional views of membrane-associated clathrin and cytoskeleton in critical-point-dried macrophages.

    Science.gov (United States)

    Aggeler, J; Takemura, R; Werb, Z

    1983-11-01

    We obtained high-resolution topographical information about the distribution of clathrin and cytoskeletal filaments on cytoplasmic membrane surfaces of macrophages spreading onto glass coverslips by both critical-point drying of broken-open cells and preparation of rotary platinum replicas. Irregular patches of the adherent ventral surface of the plasma membrane were exposed in these cells, and large areas of these exposed membranes were covered with clathrin-coated patches, pits, and vesicles. Various amounts of cytoskeleton were attached to the plasma membranes of these spreading cells, either as distinct starlike foci, or as individual filaments and bundles radiating out from the cytoskeletal meshwork. In newly adherent cells a well developed Golgi-GERL complex, characterized by smooth, dish-like cisternae associated with rough endoplasmic reticulum, was observed. There were many coated vesicles budding off from the Golgi cisternae, and these were predominantly of the large type (150 nm) usually associated with the plasma membrane. In critical-point-dried samples, both cytoskeleton and membranes were preserved in detail comparable to that of quick-frozen samples, after appropriate fixation. Rotary replication of critical-point-dried cells provides a rapid, easily controlled, and generally easy to perform method for obtaining samples of exposed membrane large enough to permit quantification of membrane-associated clathrin and cytoskeleton under various experimental conditions. PMID:6415067

  1. Supramolecular Approaches to Nanoscale Morphological Control in Organic Solar Cells

    Directory of Open Access Journals (Sweden)

    Alexander M. Haruk

    2015-06-01

    Full Text Available Having recently surpassed 10% efficiency, solar cells based on organic molecules are poised to become a viable low-cost clean energy source with the added advantages of mechanical flexibility and light weight. The best-performing organic solar cells rely on a nanostructured active layer morphology consisting of a complex organization of electron donating and electron accepting molecules. Although much progress has been made in designing new donor and acceptor molecules, rational control over active layer morphology remains a central challenge. Long-term device stability is another important consideration that needs to be addressed. This review highlights supramolecular strategies for generating highly stable nanostructured organic photovoltaic active materials by design.

  2. Emerging roles of actin cytoskeleton regulating enzymes in drug addiction: Actin or reactin’?

    OpenAIRE

    Rothenfluh, Adrian; Cowan, Christopher W.

    2013-01-01

    Neurons rely on their cytoskeleton to give them shape and stability, and on cytoskeletal dynamics for growth and synaptic plasticity. Because drug addiction is increasingly seen as the inappropriate learning of strongly reinforcing stimuli, the role of the cytoskeleton in shaping drug memories has been of increasing interest in recent years. Does the cytoskeleton have an active role in shaping these memories, and to what extent do alterations in the cytoskeleton reflect the acute actions of d...

  3. Gravisensing: Ionic responses, cytoskeleton and amyloplast behavior

    Science.gov (United States)

    Allen, N.; Chattaraj, P.; Collings, D.; Johannes, E.

    In Zea mays L., changes in orientation of stems are perceived by the pulvinal tissue, which responds to the stimulus by differential growth resulting in upward bending of the stem. Gravity is perceived in the bundle sheath cells, which contain amyloplasts that sediment to the new cell base when a change in the gravity vector occurs. The mechanism by which the mechanical signal is transduced into a physiological response is so far unknown for any gravity perceiving tissue. It is hypothesized that this involves interactions of amyloplasts with the plasma membrane and/or ER via cytoskeletal elements. To gain further insights into this process we monitored amyloplast movements in response to gravistimulation In a pharmacological approach we investigated how the dynamics of plastid sedimentation are affected by actin and microtubule disrupting drugs and modifiers of cytoplasmic pH, which is a key player in early gravitropic signaling. pHc was monitored in the cells composing the maize pulvinus before and after gravistimulation. pHc changes were only apparent within the bundle sheath cells, and not in the parenchyma cells. After turning, cytoplasmic acidification was observed at the sides of the cells, whereas the cytoplasm at the base of the cells, where plastids slowly accumulated became more basic. The results suggest that pHc has an important role in the early signaling pathways of maize stem gravitropism. Dark grown caulonemal filaments of the moss Physcomitrella patens respond to gravity vector changes with a reorientation of tip growth away from the gravity vector. Microtubule distributions in tip cells were monitored over time and seen to accumulate preferentially on the lower flank of the tip filaments 30 minutes after a 90 degree turn. Using a self-referencing Ca 2 + selective ion probe, we found that growing caulonemal filaments exhibit a Ca 2 + influx at the apical dome, similar to that reported previously for other tip growing cells. However, in

  4. Impacts of aluminum on the cytoskeleton of the maize root apex. short-term effects on the distal part of the transition zone

    Science.gov (United States)

    Sivaguru; Baluska; Volkmann; Felle; Horst

    1999-03-01

    Using monoclonal tubulin and actin antibodies, Al-mediated alterations to microtubules (MTs) and actin microfilaments (MFs) were shown to be most prominent in cells of the distal part of the transition zone (DTZ) of an Al-sensitive maize (Zea mays L.) cultivar. An early response to Al (1 h, 90 μM) was the depletion of MTs in cells of the DTZ, specifically in the outermost cortical cell file. However, no prominent changes to the MT cytoskeleton were found in elongating cells treated with Al for 1 h in spite of severe inhibition of root elongation. Al-induced early alterations to actin MFs were less dramatic and consisted of increased actin fluorescence of partially disintegrated MF arrays in cells of the DTZ. These tissue- and development-specific alterations to the cytoskeleton were preceded by and/or coincided with Al-induced depolarization of the plasma membrane and with callose formation, particularly in the outer cortex cells of the DTZ. Longer Al supplies (>6 h) led to progressive enhancements of lesions to the MT cytoskeleton in the epidermis and two to three outer cortex cell files. Our data show that the cytoskeleton in the cells of the DTZ is especially sensitive to Al, consistent with the recently proposed specific Al sensitivity of this unique, apical maize root zone. PMID:10069846

  5. STUDYING MEMBRANE ANCHOR ORGANIZATION IN LIVING CELL MEMBRANES

    OpenAIRE

    Huang, Hector Han-Li

    2011-01-01

    The cell membrane is a complex mixture of various lipids, proteins and other biomolecules that are all organized into a fluid 2-dimensional bilayer. A rather unique trait of this organelle is the lateral mobility of the component molecules. Surprisingly, these molecules are not necessarily distributed homogeneously in the membrane. From a physical perspective, these inhomogeneities are interesting because they indicate some level of organization in the membrane. From a biological perspect...

  6. Cutaneous Squamous Cell Carcinomas in Organ Transplant Recipients

    OpenAIRE

    Ramya Chockalingam; Christopher Downing; Tyring, Stephen K.

    2015-01-01

    Non-melanoma skin cancers represent a major cause of morbidity after organ transplantation. Squamous cell carcinomas (SCC) are the most common cutaneous malignancies seen in this population, with a 65–100 fold greater incidence in organ transplant recipients compared to the general population. In recent years, human papillomaviruses (HPV) of the beta genus have been implicated in the pathogenesis of post-transplant SCCs. The underlying mechanism of carcinogenesis has been attributed to the...

  7. Self-organizing actomyosin patterns on the cell cortex at epithelial cell-cell junctions.

    Science.gov (United States)

    Moore, Thomas; Wu, Selwin K; Michael, Magdalene; Yap, Alpha S; Gomez, Guillermo A; Neufeld, Zoltan

    2014-12-01

    The behavior of actomyosin critically determines morphologically distinct patterns of contractility found at the interface between adherent cells. One such pattern is found at the apical region (zonula adherens) of cell-cell junctions in epithelia, where clusters of the adhesion molecule E-cadherin concentrate in a static pattern. Meanwhile, E-cadherin clusters throughout lateral cell-cell contacts display dynamic movements in the plane of the junctions. To gain insight into the principles that determine the nature and organization of these dynamic structures, we analyze this behavior by modeling the 2D actomyosin cell cortex as an active fluid medium. The numerical simulations show that the stability of the actin filaments influences the spatial structure and dynamics of the system. We find that in addition to static Turing-type patterns, persistent dynamic behavior occurs in a wide range of parameters. In the 2D model, mechanical stress-dependent actin breakdown is shown to produce a continuously changing network of actin bridges, whereas with a constant breakdown rate, more isolated clusters of actomyosin tend to form. The model qualitatively reproduces the dynamic and stable patterns experimentally observed at the junctions between epithelial cells. PMID:25468344

  8. How Does the Modular Organization of Entorhinal Grid Cells Develop?

    Directory of Open Access Journals (Sweden)

    Stephen eGrossberg

    2014-06-01

    Full Text Available The entorhinal-hippocampal system plays a crucial role in spatial cognition and navigation. Since the discovery of grid cells in layer II of medial entorhinal cortex (MEC, several types of models have been proposed to explain their development and operation; namely, continuous attractor network models, oscillatory interference models, and self-organizing map (SOM models. Recent experiments revealing the in vivo intracellular signatures of grid cells (Domnisoru et al., 2013; Schmidt-Heiber & Hausser, 2013, the primarily inhibitory recurrent connectivity of grid cells (Couey et al., 2013; Pastoll et al., 2013, and the topographic organization of grid cells within anatomically overlapping modules of multiple spatial scales along the dorsoventral axis of MEC (Stensola et al., 2012 provide strong constraints and challenges to existing grid cell models. This article provides a computational explanation for how MEC cells can emerge through learning with grid cell properties in modular structures. Within this SOM model, grid cells with different rates of temporal integration learn modular properties with different spatial scales. Model grid cells learn in response to inputs from multiple scales of directionally-selective stripe cells (Krupic et al., 2012; Mhatre et al., 2012 that perform path integration of the linear velocities that are experienced during navigation. Slower rates of grid cell temporal integration support learned associations with stripe cells of larger scales. The explanatory and predictive capabilities of the three types of grid cell models are comparatively analyzed in light of recent data to illustrate how the SOM model overcomes problems that other types of models have not yet handled.

  9. Efficient organic solar cells processed from hydrocarbon solvents

    Science.gov (United States)

    Zhao, Jingbo; Li, Yunke; Yang, Guofang; Jiang, Kui; Lin, Haoran; Ade, Harald; Ma, Wei; Yan, He

    2016-02-01

    Organic solar cells have desirable properties, including low cost of materials, high-throughput roll-to-roll production, mechanical flexibility and light weight. However, all top-performance devices are at present processed using halogenated solvents, which are environmentally hazardous and would thus require expensive mitigation to contain the hazards. Attempts to process organic solar cells from non-halogenated solvents lead to inferior performance. Overcoming this hurdle, here we present a hydrocarbon-based processing system that is not only more environmentally friendly but also yields cells with power conversion efficiencies of up to 11.7%. Our processing system incorporates the synergistic effects of a hydrocarbon solvent, a novel additive, a suitable choice of polymer side chain, and strong temperature-dependent aggregation of the donor polymer. Our results not only demonstrate a method of producing active layers of organic solar cells in an environmentally friendly way, but also provide important scientific insights that will facilitate further improvement of the morphology and performance of organic solar cells.

  10. Mechanical Properties of Living Adherent Cells :Relationship with Structure and Function

    Institute of Scientific and Technical Information of China (English)

    R.; FODIL; S.; Féréol; E.; PLANUS; V.M.; LAURENT; B.; LOUIS; D.; ISABEY

    2005-01-01

    1 IntroductionMechanical properties of living cells are dependent on a variety of intracellular and/or extracellular factors (e.g., spatial organization of cytoskeleton (CSK) elements; internal tension; actomyosin contraction; contribution of proximal and/or more distal environment...). Because these factors are involved in biological processes as important as cell adhesion, locomotion, cell contraction, signalization, understanding the relationships between cell mechanical properties, structure and functio...

  11. Stability and Degradation of Organic and Polymer Solar Cells

    DEFF Research Database (Denmark)

    Organic photovoltaics (OPV) are a new generation of solar cells with the potential to offer very short energy pay back times, mechanical flexibility and significantly lower production costs compared to traditional crystalline photovoltaic systems. A weakness of OPV is their comparative instability...... during operation and this is a critical area of research towards the successful development and commercialization of these 3rd generation solar cells. Covering both small molecule and polymer solar cells, Stability and Degradation of Organic and Polymer Solar Cells summarizes the state of the art...... understanding of stability and provides a detailed analysis of the mechanisms by which degradation occurs. Following an introductory chapter which compares different photovoltaic technologies, the book focuses on OPV degradation, discussing the origin and characterization of the instability and describing...

  12. Differing astrocytic cytoskeleton alterations in alzheimer's disease

    Czech Academy of Sciences Publication Activity Database

    Olabarria, M.; Noristani, H.; Chvátal, Alexandr; Verkhratsky, Alexei; Rodríguez Arellano, Jose Julio

    2009-01-01

    Roč. 57, č. 13 (2009), S103-S104. ISSN 0894-1491. [European Meeting on Glial Cells in Health and Disease /9./. 09.09.2009-12.09.2009, Paris] Institutional research plan: CEZ:AV0Z50390703 Keywords : Alzheimer ´s disease Subject RIV: FH - Neurology

  13. The Emerging Role of Nanotechnology in Cell and Organ Transplantation.

    Science.gov (United States)

    Tasciotti, Ennio; Cabrera, Fernando J; Evangelopoulos, Michael; Martinez, Jonathan O; Thekkedath, Usha R; Kloc, Malgorzata; Ghobrial, Rafik M; Li, Xian C; Grattoni, Alessandro; Ferrari, Mauro

    2016-08-01

    Transplantation is often the only choice many patients have when suffering from end-stage organ failure. Although the quality of life improves after transplantation, challenges, such as organ shortages, necessary immunosuppression with associated complications, and chronic graft rejection, limit its wide clinical application. Nanotechnology has emerged in the past 2 decades as a field with the potential to satisfy clinical needs in the area of targeted and sustained drug delivery, noninvasive imaging, and tissue engineering. In this article, we provide an overview of popular nanotechnologies and a summary of the current and potential uses of nanotechnology in cell and organ transplantation. PMID:27257995

  14. Formation of organic crystalline nanopillar arrays and their application to organic photovoltaic cells.

    Science.gov (United States)

    Hirade, Masaya; Nakanotani, Hajime; Yahiro, Masayuki; Adachi, Chihaya

    2011-01-01

    To enhance the performance of organic photovoltaic (OPV) cells, preparation of organic nanometer-sized pillar arrays is fascinating because a significantly large area of a donor/acceptor heterointerface having continuous conduction path to both anode and cathode electrodes can be realized. In this study, we grew cupper phthalocyanine (CuPc) crystalline nanopillar arrays by conventional thermal gradient sublimation technique using a few-nanometer-sized trigger seeds composed of a CuPc and 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) stacked layer. We optimized the pillar density by tuning crystal growth condition in order to apply it to OPV cells. PMID:21194207

  15. Investigations on quinquethiophenes as donor materials in organic solar cells

    International Nuclear Information System (INIS)

    Organic photovoltaics could in the future represent a possibility for energy production from renewable energy sources. The advance consists here first of all in the potential of a very reasonable fabrication, for instance a production in the role-to-role procedurre, which can be prusued so on flexible substrates like for instance foils. Although the material costs are low, until the commercialization of organic solar cells among others an increasement of their power efficiency is necessary. Preferably in organic solar cells donor and acceptor materials should be applied, the absorption spectra and energy levels of which are ideally matched, because so can high zero-current voltages be reached. Additionally high absorption coefficents of the materials over a large spectral range can lead to high current densities in these photovoltaic components. In this thesis novel quinquethiophenes as donors in organic solar cells are studied, which consist as basic unit of five thiophene rings as well as dicyanovinyl end groups and alkyl side chains. The studied materials possess a high absorption coefficient and reach because of the high ionization potential high zero-current voltages in organic solar cells under application of the fullerenet C60 as acceptor. Simultaneously a efficient separation of the excitons on the acceptor-donor interface occurs. However the high ionization potential of the quinquethiophenes puts special requirements to the further solar-cell structure. Within this thesis it is shown that adifference between internal voltage and zero-current voltage influences decidingly the shape of the solar-cell characteristic and can generate a S-shape in the neighbourhood of the zero-current voltage. The internal voltage is hereby determined by the contacting of the photoactive layers. An increasement of the internal voltage of the solar cell can be reached by a corresponding material choice. So in this thesis it is shown that organic solar cells based on these

  16. ANAEROBIC BIODEGRADATION OF ORGANIC COMPOUNDS IN MICROBIAL FUEL CELLS

    Directory of Open Access Journals (Sweden)

    Samkov A. A.

    2014-09-01

    Full Text Available МF-4SК membrane-based microbial fuel cell (MFC was used for an anaerobic utilization of organic com-pounds of various liquid wastes. During incubation in short circuit mode, decreasing of the COD value on range 30-87 % depending on the type of wastes was detected. The dependence of the microbial fuel cell output power on the value of the external load was determined by a number of structural characteristics of MFC

  17. Fluoride inhibits the response of bone cells to mechanical loading

    NARCIS (Netherlands)

    H.M.E. Willems; E.G.H.M. van den Heuvel; S. Castelein; J. Keverling Buisman; A.L.J.J. Bronckers; A.D. Bakker; J. Klein-Nulend

    2011-01-01

    The response of bone cells to mechanical loading is mediated by the cytoskeleton. Since the bone anabolic agent fluoride disrupts the cytoskeleton, we investigated whether fluoride affects the response of bone cells to mechanical loading, and whether this is cytoskeleton mediated. The mechano-respon

  18. Geometry-driven cell organization determines tissue growths in scaffold pores: consequences for fibronectin organization.

    Directory of Open Access Journals (Sweden)

    Pascal Joly

    Full Text Available To heal tissue defects, cells have to bridge gaps and generate new extracellular matrix (ECM. Macroporous scaffolds are frequently used to support the process of defect filling and thus foster tissue regeneration. Such biomaterials contain micro-voids (pores that the cells fill with their own ECM over time. There is only limited knowledge on how pore geometry influences cell organization and matrix production, even though it is highly relevant for scaffold design. This study hypothesized that 1 a simple geometric description predicts cellular organization during pore filling at the cell level and that 2 pore closure results in a reorganization of ECM. Scaffolds with a broad distribution of pore sizes (macroporous starPEG-heparin cryogel were used as a model system and seeded with primary fibroblasts. The strategies of cells to fill pores could be explained by a simple geometrical model considering cells as tensioned chords. The model matched qualitatively as well as quantitatively by means of cell number vs. open cross-sectional area for all pore sizes. The correlation between ECM location and cell position was higher when the pores were not filled with tissue (Pearson's coefficient ρ = 0.45±0.01 and reduced once the pores were closed (ρ = 0.26±0.04 indicating a reorganization of the cell/ECM network. Scaffold pore size directed the time required for pore closure and furthermore impacted the organization of the fibronectin matrix. Understanding how cells fill micro-voids will help to design biomaterial scaffolds that support the endogenous healing process and thus allow a fast filling of tissue defects.

  19. Thiophene And Anthracene Containing Polymers In Organic Solar Cells

    International Nuclear Information System (INIS)

    Organic solar cell research has attracted worldwide attention during the last two decades. Organic semiconductors are easily processable, light weight, easy to integrate in a wide variety of devices and have chemically tunable properties. These properties describe the advantages of organic plastic solar cells over that of conventional silicon solar cells. Conjugated polymers, also known as semiconducting polymers, are distinguished by alternating single and double bonds between carbon atoms on the polymer backbone. Among π-conjugated polymers, polythiophenes are promising candidates for organic solar cell research. At present, the commonly used polythiophene derivatives, as the electron donor in polymer solar cells, are mainly poly(3-hexylthiophene)s (P3HT). In this study, we investigated the effect of solvent, annealing on the performance and morphology of novel two thiophene-[P1 (MEH-PPE1-PThV2) and P2 (MEH-PThE1-PPV2)] as well as two anthracene- containing poly (phenylene-ethynylene) family of polymers [P3 (MEH-PPE1-PAnV2) and P4 (MEH-PAnE1-PPV2)] and (1-(3-methoxycarbonyl) propyl-1-phenyl[6,6]C61) (PCBM) based organic solar cells. The devices using the blends of P2 as donor and PCBM as acceptor (1:3 weight ratio) exhibited a short circuit current of JSC = 5.2 mA/cm2, an open circuit voltage of VOC 800 mV, fill factor FF = 0.4 and resulting power conversion efficiency ηAM1.5 = 1.8 %.

  20. Chaperonin filaments: The archaeal cytoskeleton?

    Science.gov (United States)

    Trent, Jonathan D.; Kagawa, Hiromi K.; Yaoi, Takuro; Olle, Eric; Zaluzec, Nestor J.

    1997-01-01

    Chaperonins are high molecular mass double-ring structures composed of 60-kDa protein subunits. In the hyperthermophilic archaeon Sulfolobus shibatae the two chaperonin proteins represent ≈4% of its total protein and have a combined intracellular concentration of >30 mg/ml. At concentrations ≥ 0.5 mg/ml purified chaperonins form filaments in the presence of Mg2+ and nucleotides. Filament formation requires nucleotide binding (not hydrolysis), and occurs at physiological temperatures in biologically relevant buffers, including a buffer made from cell extracts. These observations suggest that chaperonin filaments may exist in vivo and the estimated 4600 chaperonins per cell suggest that such filaments could form an extensive cytostructure. We observed filamentous structures in unfixed, uranyl-acetate-stained S. shibatae cells, which resemble the chaperonin filaments in size and appearance. ImmunoGold (Janssen) labeling using chaperonin antibodies indicated that many chaperonins are associated with insoluble cellular structures and these structures appear to be filamentous in some areas, although they could not be uranyl-acetate-stained. The existence of chaperonin filaments in vivo suggests a mechanism whereby their protein-folding activities can be regulated. More generally, the filaments themselves may play a cytoskeletal role in Archaea. PMID:9144246

  1. Citoesqueleto e mecanotransdução na fisiopatologia da lesão pulmonar induzida por ventilador Cytoskeleton and mechanotransduction in the pathophysiology of ventilator-induced lung injury

    Directory of Open Access Journals (Sweden)

    Leandro Utino Taniguchi

    2010-06-01

    Full Text Available A ventilação mecânica é uma terapia importante, mas pode resultar em complicações. Uma das mais relevantes é a lesão pulmonar induzida por ventilador. Devido à hiperdistensão alveolar, o pulmão inicia um processo inflamatório, com infiltrado neutrofílico, formação de membrana hialina, fibrogênese e prejuízo de troca gasosa. Nesse processo, a mecanotransdução da hiperdistensão celular é mediada através do citoesqueleto da célula e de suas interações com a matriz extracelular e com as células vizinhas, de modo que o estímulo mecânico da ventilação se traduz em sinalização bioquímica intracelular, desencadeando ativação endotelial, permeabilidade vascular pulmonar, quimiotaxia leucocitária, produção de citocinas e, possivelmente, lesão de órgãos à distância. Estudos clínicos demonstram essa relação entre distensão pulmonar e mortalidade em pacientes com lesão pulmonar induzida por ventilador. Entretanto, apesar de o citoesqueleto ter um papel fundamental na patogênese da lesão pulmonar induzida por ventilador, a literatura carece de estudos utilizando modelos in vivo sobre as alterações do citoesqueleto e de suas proteínas associadas durante esse processo patológico.Although mechanical ventilation is an important therapy, it can result in complications. One major complication is ventilator-induced lung injury, which is caused by alveolar hyperdistension, leading to an inflammatory process, with neutrophilic infiltration, hyaline membrane formation, fibrogenesis and impaired gas exchange. In this process, cellular mechanotransduction of the overstretching stimulus is mediated by means of the cytoskeleton and its cell-cell and cell-extracellular matrix interactions, in such a way that the mechanical stimulus of ventilation is translated into an intracellular biochemical signal, inducing endothelial activation, pulmonary vascular permeability, leukocyte chemotaxis, cytokine production and, possibly

  2. Air stable organic-inorganic nanoparticles hybrid solar cells

    Science.gov (United States)

    Qian, Lei; Yang, Jihua; Xue, Jiangeng; Holloway, Paul H.

    2015-09-29

    A solar cell includes a low work function cathode, an active layer of an organic-inorganic nanoparticle composite, a ZnO nanoparticle layer situated between and physically contacting the cathode and active layers; and a transparent high work function anode that is a bilayer electrode. The inclusion of the ZnO nanoparticle layer results in a solar cell displaying a conversion efficiency increase and reduces the device degradation rate. Embodiments of the invention are directed to novel ZnO nanoparticles that are advantageous for use as the ZnO nanoparticle layers of the novel solar cells and a method to prepare the ZnO nanoparticles.

  3. Nanowire networks as a transparent electrode for organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Sachse, Christoph; Kim, Yong-Hyun; Mueller-Meskamp, Lars; Leo, Karl [Institut fuer Angewandte Photophysik, Dresdner Innovationszentrum Energieeffizienz, TU Dresden, 01062 Dresden (Germany)

    2011-07-01

    For a broad application of organic thin film solar cells, inexpensive roll-to-roll processing on flexible and lightweight substrates is desirable. On these flexible substrates, commonly used ITO electrodes do not show satisfying performance due to the brittle nature of anorganic oxides. Among other alternatives, recently some promising results using silver-nanowires as a conductive layer were published. Such close-meshed metal grids are capable of combining the high conductivity of metals with the transparency caused by low surface coverage. Ontop, the solution based process guarantees low manufacturing costs. Here, we evaluate and improve this alternative electrode material for organic solar cells. We achieve suitable film homogeneities with a simple dip or spray-coating process on different substrates. After post-processing an ITO-like performance is obtained. Apart from the optimization of the electrode parameters, the thin organic solar cell stack imposes special requirements on the electrode technology. Therefore, our established small molecule technology is used to evaporate organic solar cells on the nanowire electrodes and measure their performance to find suitable combinations.

  4. Modeling nanostructure-enhanced light trapping in organic solar cells

    DEFF Research Database (Denmark)

    Adam, Jost

    A promising approach for improving the power conversion efficiencies of organic solar cells (OSCs) is by incorporating nanostructures in their thin film architecture to improve the light absorption in the device’s active polymer layers. Here, we present a modelling framework for the prediction...

  5. Repair of defects in photoactive layer of organic solar cells

    NARCIS (Netherlands)

    Oostra, A.J.; Blom, P.W.M.; Michels, J.J.

    2015-01-01

    Defects occurring during printing of the photoactive layer in organic solar cells lead to short-circuits due to direct contact between the PEDOT:PSS anode and metallic cathode. We provide a highly effective repair method where the defected zone with bare PEDOT:PSS is treated with aqueous sodium hypo

  6. Electrochemical investigations on magnesium/N-halogen organic cell systems

    Energy Technology Data Exchange (ETDEWEB)

    Udhayan, R.; Bhatt, D.P. (Central Electrochemical Research Inst., Karaikudi (India))

    1992-09-01

    This paper reports the results of the experimental studies on various magnesium/magnesium perchlorate/N-halogen organic cell systems employing a constant current discharge method. Several battery parameters, viz. internal resistance, capacity, energy density and coulombic efficiency have been calculated. High open circuit potential (around 1000 mV), open circuit voltage (2.45-2.67 V) and closed circuit voltage (2.30-2.44 V) and non-toxicity are the important and attractive features of these organic cell systems. The trend of the capacities of various magnesium cell systems with respect to the chosen N-halogen organic cathodes is obtained as follows: N,N'-dichlorodimethylhydantoin (DDH) > trichloroisocyanuric acid (TCIA) > dichloroisocyanuric acid (DCIA) > trichloro melamine (TCM). The energy densities of DDH, TCIA, DCIA and TCM based cells are found to be 798, 660, 420 and 95 Wh (kg of N-halogen organic compound){sup -1}, respectively. Cyclic voltammetric behaviour of a typical compound, viz. N,N'-dichlorodimethylhydantoin, has also been studied. (Author).

  7. Anomalous charge storage exponents of organic bulk heterojunction solar cells.

    Science.gov (United States)

    Nair, Pradeep; Dwivedi, Raaz; Kumar, Goutam; Dept of Electrical Engineering, IIT Bombay Team

    2013-03-01

    Organic bulk heterojunction (BHJ) devices are increasingly being researched for low cost solar energy conversion. The efficiency of such solar cells is dictated by various recombination processes involved. While it is well known that the ideality factor and hence the charge storage exponents of conventional PN junction diodes are influenced by the recombination processes, the same aspects are not so well understood for organic solar cells. While dark currents of such devices typically show an ideality factor of 1 (after correcting for shunt resistance effects, if any), surprisingly, a wide range of charge storage exponents for such devices are reported in literature alluding to apparent concentration dependence for bi-molecular recombination rates. In this manuscript we critically analyze the role of bi-molecular recombination processes on charge storage exponents of organic solar cells. Our results indicate that the charge storage exponents are fundamentally influenced by the electrostatics and recombination processes and can be correlated to the dark current ideality factors. We believe that our findings are novel, and advance the state-of the art understanding on various recombination processes that dictate the performance limits of organic solar cells. The authors would like to thank the Centre of Excellence in Nanoelectronics (CEN) and the National Centre for Photovoltaic Research and Education (NCPRE), IIT Bombay for computational and financial support

  8. Organic solar cell. Final report; Organische Solarzelle. Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-09-01

    The project was carried out in order to characterize and define the potential of organic solar cells. The system of copper phthalocyanine (CuPc) on indium oxide (ITO) was investigated in this report. (MM) [Deutsch] Ziel des Projektes war die Charakterisierung und Abgrenzung des Potentials organischer Solarzellen. In diesem Bericht wurde das System Kupferphthalocyanin (CuPc) auf Indiumoxid (ITO) untersucht. (MM)

  9. Clathrin-dependent pathways and the cytoskeleton network are involved in ceramide endocytosis by a parasitic protozoan, Giardia lamblia

    OpenAIRE

    Hernandez, Yunuen; Castillo, Cynthia; Roychowdhury, Sukla; Hehl, Adrian; Aley, Stephen B.; Das, Siddhartha

    2006-01-01

    Although identified as an early-diverged protozoan, Giardia lamblia shares many similarities with higher eukaryotic cells, including an internal membrane system and cytoskeleton, as well as secretory pathways. However, unlike many other eukaryotes, Giardia does not synthesize lipids de novo, but rather depends on exogenous sources for both energy production and organelle or membrane biogenesis. It is not known how lipid molecules are taken up by this parasite and if endocytic pathways are inv...

  10. Multiple effects of electroporation on the adhesive behaviour of breast cancer cells and fibroblasts

    Directory of Open Access Journals (Sweden)

    Pehlivanova Viktoria N

    2012-03-01

    provoke changes in the cytoskeleton organization and cell adhesiveness, which could contribute to the restriction of tumour invasion and thus leads to the amplification of anti-tumour effect of electroporation-based tumour therapy.

  11. Does myo-inositol effect on PCOS follicles involve cytoskeleton regulation?

    Science.gov (United States)

    Bizzarri, Mariano; Cucina, Alessandra; Dinicola, Simona; Harrath, Abdel Halim; Alwasel, Saleh H; Unfer, Vittorio; Bevilacqua, Arturo

    2016-06-01

    Inositol metabolism is severely impaired in follicles obtained from cystic ovaries, leading to deregulated insulin transduction and steroid synthesis. On the contrary, inositol administration to women suffering from polycystic ovary syndrome (PCOS) has been proven to efficiently counteract most of the clinical hallmarks displayed by PCOS patients, including insulin resistance, hyperandrogenism and oligo-amenorrhea. We have recently observed that myo-inositol induces significant changes in cytoskeletal architecture of breast cancer cells, by modulating different biochemical pathways, eventually modulating the epithelial-mesenchymal transition. We hypothesize that inositol and its monophosphate derivatives, besides their effects on insulin transduction, may efficiently revert histological and functional features of cystic ovary by inducing cytoskeleton rearrangements. We propose an experimental model that could address not only whether inositol modulates cytoskeleton dynamics in both normal and cystic ovary cells, but also whether this effect may interfere with ovarian steroidogenesis. A more compelling understanding of the mechanisms of action of inositol (and its derivatives) would greatly improve its therapeutic utilization, by conferring to current treatments a well-grounded scientific rationale. PMID:27142131

  12. The Roles of RNase-L in Antimicrobial Immunity and the Cytoskeleton-Associated Innate Response

    Directory of Open Access Journals (Sweden)

    Heather J. Ezelle

    2016-01-01

    Full Text Available The interferon (IFN-regulated endoribonuclease RNase-L is involved in multiple aspects of the antimicrobial innate immune response. It is the terminal component of an RNA cleavage pathway in which dsRNA induces the production of RNase-L-activating 2-5A by the 2′-5′-oligoadenylate synthetase. The active nuclease then cleaves ssRNAs, both cellular and viral, leading to downregulation of their expression and the generation of small RNAs capable of activating retinoic acid-inducible gene-I (RIG-I-like receptors or the nucleotide-binding oligomerization domain-like receptor 3 (NLRP3 inflammasome. This leads to IFNβ expression and IL-1β activation respectively, in addition to broader effects on immune cell function. RNase-L is also one of a growing number of innate immune components that interact with the cell cytoskeleton. It can bind to several cytoskeletal proteins, including filamin A, an actin-binding protein that collaborates with RNase-L to maintain the cellular barrier to viral entry. This antiviral activity is independent of catalytic function, a unique mechanism for RNase-L. We also describe here the interaction of RNase-L with the E3 ubiquitin ligase and scaffolding protein, ligand of nump protein X (LNX, a regulator of tight junction proteins. In order to better understand the significance and context of these novel binding partners in the antimicrobial response, other innate immune protein interactions with the cytoskeleton are also discussed.

  13. The Roles of RNase-L in Antimicrobial Immunity and the Cytoskeleton-Associated Innate Response.

    Science.gov (United States)

    Ezelle, Heather J; Malathi, Krishnamurthy; Hassel, Bret A

    2016-01-01

    The interferon (IFN)-regulated endoribonuclease RNase-L is involved in multiple aspects of the antimicrobial innate immune response. It is the terminal component of an RNA cleavage pathway in which dsRNA induces the production of RNase-L-activating 2-5A by the 2'-5'-oligoadenylate synthetase. The active nuclease then cleaves ssRNAs, both cellular and viral, leading to downregulation of their expression and the generation of small RNAs capable of activating retinoic acid-inducible gene-I (RIG-I)-like receptors or the nucleotide-binding oligomerization domain-like receptor 3 (NLRP3) inflammasome. This leads to IFNβ expression and IL-1β activation respectively, in addition to broader effects on immune cell function. RNase-L is also one of a growing number of innate immune components that interact with the cell cytoskeleton. It can bind to several cytoskeletal proteins, including filamin A, an actin-binding protein that collaborates with RNase-L to maintain the cellular barrier to viral entry. This antiviral activity is independent of catalytic function, a unique mechanism for RNase-L. We also describe here the interaction of RNase-L with the E3 ubiquitin ligase and scaffolding protein, ligand of nump protein X (LNX), a regulator of tight junction proteins. In order to better understand the significance and context of these novel binding partners in the antimicrobial response, other innate immune protein interactions with the cytoskeleton are also discussed. PMID:26760998

  14. Recyclable organic solar cells on cellulose nanocrystal substrates.

    Science.gov (United States)

    Zhou, Yinhua; Fuentes-Hernandez, Canek; Khan, Talha M; Liu, Jen-Chieh; Hsu, James; Shim, Jae Won; Dindar, Amir; Youngblood, Jeffrey P; Moon, Robert J; Kippelen, Bernard

    2013-01-01

    Solar energy is potentially the largest source of renewable energy at our disposal, but significant advances are required to make photovoltaic technologies economically viable and, from a life-cycle perspective, environmentally friendly, and consequently scalable. Cellulose nanomaterials are emerging high-value nanoparticles extracted from plants that are abundant, renewable, and sustainable. Here, we report on the first demonstration of efficient polymer solar cells fabricated on optically transparent cellulose nanocrystal (CNC) substrates. The solar cells fabricated on the CNC substrates display good rectification in the dark and reach a power conversion efficiency of 2.7%. In addition, we demonstrate that these solar cells can be easily separated and recycled into their major components using low-energy processes at room temperature, opening the door for a truly recyclable solar cell technology. Efficient and easily recyclable organic solar cells on CNC substrates are expected to be an attractive technology for sustainable, scalable, and environmentally-friendly energy production. PMID:23524333

  15. Recyclable organic solar cells on substrates comprising cellulose nanocrystals (CNC)

    Energy Technology Data Exchange (ETDEWEB)

    Kippelen, Bernard; Fuentes-Hernandez, Canek; Zhou, Yinhua; Moon, Robert; Youngblood, Jeffrey P

    2015-12-01

    Recyclable organic solar cells are disclosed herein. Systems and methods are further disclosed for producing, improving performance, and for recycling the solar cells. In certain example embodiments, the recyclable organic solar cells disclosed herein include: a first electrode; a second electrode; a photoactive layer disposed between the first electrode and the second electrode; an interlayer comprising a Lewis basic oligomer or polymer disposed between the photoactive layer and at least a portion of the first electrode or the second electrode; and a substrate disposed adjacent to the first electrode or the second electrode. The interlayer reduces the work function associated with the first or second electrode. In certain example embodiments, the substrate comprises cellulose nanocrystals that can be recycled. In certain example embodiments, one or more of the first electrode, the photoactive layer, and the second electrode may be applied by a film transfer lamination method.

  16. Microfilamin - a new protein of the cytoskeleton with molecular weight 53,000

    International Nuclear Information System (INIS)

    The microfilaments in cultured cells participate in many vitally important processes: endocytosis, movement of cells, division, etc. One of the approaches to the study of the proteins of the microfilaments is the use of the hybridoma technique. This method permits the use of cell structures as an immunogen and the investigation of their protein assortment by means of monoclonal antibodies. Using such an approach, the authors were able to identify a protein with molecular weight 53 kilodaltons, not previously described in the microfilaments. BABL/c mice were immunized with an extract of the cytoskeleton of murine cells 3T3. It was produced by treating the cells with 0.5% Triton in a buffer stabilizing the cytoskeleton (10 mM sodium phosphate buffer, pH 6.8, 0.1 M KCl, 1 mMEGTA, 0.1 mM EDTA, 5 mM MgCl2, and 2 M sucrose), and then with the same buffer, containing 1 micrograms/ml DNase I, 1mM PMSF, and 20 units/ml trasylol. The extract was clarified by successive centrifugation at 1000, 1200, and 10,000 g. Splenocytes of immune animals were hybridized with murine myeloma SP 2/0-Ag 14 cells and screening of the hybridomas was performed by the method of indirect immunofluorescence on murine cells of the 3T3 line stained with Coomassie blue. Data from autograph after incubation with E9-48 antibodies and 125I-labeled rabbit anti-mouse immunoglobulins are presented as well. The authors named this new technique microfilamin since it is detected in structures containing microfilaments: stress fibrils, the active edge, surface villi, and others

  17. Recent Advancements and Techniques in Manufacture of Solar Cells: Organic Solar Cells

    Directory of Open Access Journals (Sweden)

    B. Naga Venkata Sai Ganesh,

    2013-03-01

    Full Text Available The major problem faced by the society is power crisis. All the non-renewable resources like fossil fuelsnecessary for producing power are being used excessively, which might result a day in future where, the world might godark due to lack of power producing resources. Usage of renewable resources like solar energy can be a solution to thisproblem. Solar cells invented to overcome this problem show rigidity in their structure which is a drawback. Inorganicsolar cells are rigid and can be mounted only on rooftops. Hence only upper surface of buildings are utilized. In this paperwe bring out a new era or solar cells- organic solar cells, which are flexible. These organic solar cells offer the bestsolution for the above problem for a tradeoff of efficiency. This paper briefs the manufacturing technique of solar cellsfrom plastic i.e. ,organic polymers, their architecture, the working process of solar energy production from the organicsolar cells with their ease of usage

  18. Migration of Drosophila intestinal stem cells across organ boundaries.

    Science.gov (United States)

    Takashima, Shigeo; Paul, Manash; Aghajanian, Patrick; Younossi-Hartenstein, Amelia; Hartenstein, Volker

    2013-05-01

    All components of the Drosophila intestinal tract, including the endodermal midgut and ectodermal hindgut/Malpighian tubules, maintain populations of dividing stem cells. In the midgut and hindgut, these stem cells originate from within larger populations of intestinal progenitors that proliferate during the larval stage and form the adult intestine during metamorphosis. The origin of stem cells found in the excretory Malpighian tubules ('renal stem cells') has not been established. In this paper, we investigate the migration patterns of intestinal progenitors that take place during metamorphosis. Our data demonstrate that a subset of adult midgut progenitors (AMPs) move posteriorly to form the adult ureters and, consecutively, the renal stem cells. Inhibiting cell migration by AMP-directed expression of a dominant-negative form of Rac1 protein results in the absence of stem cells in the Malpighian tubules. As the majority of the hindgut progenitor cells migrate posteriorly and differentiate into hindgut enterocytes, a group of the progenitor cells, unexpectedly, invades anteriorly into the midgut territory. Consequently, these progenitor cells differentiate into midgut enterocytes. The midgut determinant GATAe is required for the differentiation of midgut enterocytes derived from hindgut progenitors. Wingless signaling acts to balance the proportion of hindgut progenitors that differentiate as midgut versus hindgut enterocytes. Our findings indicate that a stable boundary between midgut and hindgut/Malpighian tubules is not established during early embryonic development; instead, pluripotent progenitor populations cross in between these organs in both directions, and are able to adopt the fate of the organ in which they come to reside. PMID:23571215

  19. Active Cellular Mechanics and Information Processing in the Living Cell

    Science.gov (United States)

    Rao, M.

    2014-07-01

    I will present our recent work on the organization of signaling molecules on the surface of living cells. Using novel experimental and theoretical approaches we have found that many cell surface receptors are organized as dynamic clusters driven by active currents and stresses generated by the cortical cytoskeleton adjoining the cell surface. We have shown that this organization is optimal for both information processing and computation. In connecting active mechanics in the cell with information processing and computation, we bring together two of the seminal works of Alan Turing.

  20. Spectrins in axonal cytoskeletons: Dynamics revealed by extensions and fluctuations

    Science.gov (United States)

    Lai, Lipeng; Cao, Jianshu

    2014-07-01

    The macroscopic properties, the properties of individual components, and how those components interact with each other are three important aspects of a composited structure. An understanding of the interplay between them is essential in the study of complex systems. Using axonal cytoskeleton as an example system, here we perform a theoretical study of slender structures that can be coarse-grained as a simple smooth three-dimensional curve. We first present a generic model for such systems based on the fundamental theorem of curves. We use this generic model to demonstrate the applicability of the well-known worm-like chain (WLC) model to the network level and investigate the situation when the system is stretched by strong forces (weakly bending limit). We specifically studied recent experimental observations that revealed the hitherto unknown periodic cytoskeleton structure of axons and measured the longitudinal fluctuations. Instead of focusing on single molecules, we apply analytical results from the WLC model to both single molecule and network levels and focus on the relations between extensions and fluctuations. We show how this approach introduces constraints to possible local dynamics of the spectrin tetramers in the axonal cytoskeleton and finally suggests simple but self-consistent dynamics of spectrins in which the spectrins in one spatial period of axons fluctuate in-sync.

  1. Solution-processed organic trilayer solar cells incorporating conjugated polyelectrolytes

    Science.gov (United States)

    Cha, Myoung Joo; Seo, Jung Hwa

    2016-01-01

    We report solution-processed organic trilayer solar cells consisting of a bottom poly(3-hexylthiophene) (P3HT) layer, a conjugated polyelectrolyte (CPE) interlayer and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) top layer, wherein the CPE exists as an interlayer within the donor-acceptor junction. The influence of interlayer thickness on device properties was investigated, as well as the behavior of molecular dipoles in the trilayer solar cells when influenced by external electrical stimuli. We found that incorporation of an interlayer which is too thick results in decreased performance due to reduced short-circuit current (JSC), open-circuit voltage (VOC), and fill factor (FF). However the VOC is found to increase significantly when a thin CPE layer is used in conjunction with an external electric field. These results provide an experimental approach to probe the influence of interfacial dipoles on the solar cell parameters and behavior of charge separating organic donor/acceptor junctions, yielding fundamental information about the influence of electrical dipoles on the donor/acceptor interface in organic solar cells.

  2. Regeneration of Tissues and Organs Using Autologous Cells

    Energy Technology Data Exchange (ETDEWEB)

    Anthony Atala

    2010-04-28

    The Joint Commission for Health Care Organizations recently declared the shortage of transplantable organs and tissues a public health crisis. As such, there is about one death every 30 seconds due to organ failure. Complications and rejection are still significant albeit underappreciated problems. It is often overlooked that organ transplantation results in the patient being placed on an immune suppression regimen that will ultimate shorten their life span. Patients facing reconstruction often find that surgery is difficult or impossible due to the shortage of healthy autologous tissue. In many cases, autografting is a compromise between the condition and the cure that can result in substantial diminution of quality of life. The national cost of caring for persons who might benefit from engineered tissues or organs has reached $600 billion annually. Autologous tissue technologies have been developed as an alternative to transplantation or reconstructive surgery. Autologous tissues derived from the patient's own cells are capable of correcting numerous pathologies and injuries. The use of autologous cells eliminates the risks of rejection and immunological reactions, drastically reduces the time that patients must wait for lifesaving surgery, and negates the need for autologous tissue harvest, thereby eliminating the associated morbidities. In fact, the use of autologous tissues to create functional organs is one of the most important and groundbreaking steps ever taken in medicine. Although the basic premise of creating tissues in the laboratory has progressed dramatically, only a limited number of tissue developments have reached the patients to date. This is due, in part, to the several major technological challenges that require solutions. To that end, we have been in pursuit of more efficient ways to expand cells in vitro, methods to improve vascular support so that relevant volumes of engineered tissues can be grown, and constructs that can mimic the

  3. Photoconversion of organic materials into single-cell protein

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, P.F.

    1991-12-31

    A process is described for converting organic materials (such as biomass wastes) into sterile, high-grade bacterial protein suitable for use an animal feed or human food supplements. In a preferred embodiment the process involves thermally gasifying the organic material into primarily carbon monoxide, hydrogen and nitrogen products, followed by photosynthetic bacterial assimilation of the gases into cell material, which can be high as 65% protein. The process is ideally suited for waste recycling and for food production under zero-gravity or extra-terrestrial conditions.

  4. How cells (might) sense microgravity

    Science.gov (United States)

    Ingber, D.

    1999-01-01

    This article is a summary of a lecture presented at an ESA/NASA Workshop on Cell and Molecular Biology Research in Space that convened in Leuven, Belgium, in June 1998. Recent studies are reviewed which suggest that cells may sense mechanical stresses, including those due to gravity, through changes in the balance of forces that are transmitted across transmembrane adhesion receptors that link the cytoskeleton to the extracellular matrix and to other cells (e.g., integrins, cadherins, selectins). The mechanism by which these mechanical signals are transduced and converted into a biochemical response appears to be based, in part, on the finding that living cells use a tension-dependent form of architecture, known as tensegrity, to organize and stabilize their cytoskeleton. Because of tensegrity, the cellular response to stress differs depending on the level of pre-stress (pre-existing tension) in the cytoskeleton and it involves all three cytoskeletal filament systems as well as nuclear scaffolds. Recent studies confirm that alterations in the cellular force balance can influence intracellular biochemistry within focal adhesion complexes that form at the site of integrin binding as well as gene expression in the nucleus. These results suggest that gravity sensation may not result from direct activation of any single gravioreceptor molecule. Instead, gravitational forces may be experienced by individual cells in the living organism as a result of stress-dependent changes in cell, tissue, or organ structure that, in turn, alter extracellular matrix mechanics, cell shape, cytoskeletal organization, or internal pre-stress in the cell-tissue matrix.--Ingber, D. How cells (might) sense microgravity.

  5. Lamination of organic solar cells and organic light emitting devices: Models and experiments

    Energy Technology Data Exchange (ETDEWEB)

    Oyewole, O. K. [Department of Theoretical and Applied Physics, African University of Science and Technology, Km 10 Airport Road, Galadimawa, Abuja, Federal Capital Territory (Nigeria); Department of Materials Science and Engineering, Kwara State University, P.M.B 1530, Ilorin, Kwara State (Nigeria); Yu, D. [Department of Mechanical and Aerospace Engineering, Princeton University, Olden Street, Princeton, New Jersey 08544 (United States); Princeton Institute of Science and Technology of Materials, Princeton University, 70 Prospect Street, Princeton, New Jersey 08544 (United States); Du, J. [Department of Mechanical and Aerospace Engineering, Princeton University, Olden Street, Princeton, New Jersey 08544 (United States); Princeton Institute of Science and Technology of Materials, Princeton University, 70 Prospect Street, Princeton, New Jersey 08544 (United States); Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, 137 Reber Building, University Park, Pennsylvania (United States); Asare, J.; Fashina, A. [Department of Theoretical and Applied Physics, African University of Science and Technology, Km 10 Airport Road, Galadimawa, Abuja, Federal Capital Territory (Nigeria); Anye, V. C. [Department of Materials Science and Engineering, African University of Science and Technology, Km 10 Airport Road, Galadimawa, Abuja, Federal Capital Territory (Nigeria); Zebaze Kana, M. G. [Department of Materials Science and Engineering, Kwara State University, P.M.B 1530, Ilorin, Kwara State (Nigeria); Soboyejo, W. O., E-mail: soboyejo@princeton.edu [Department of Mechanical and Aerospace Engineering, Princeton University, Olden Street, Princeton, New Jersey 08544 (United States); Princeton Institute of Science and Technology of Materials, Princeton University, 70 Prospect Street, Princeton, New Jersey 08544 (United States); Department of Materials Science and Engineering, African University of Science and Technology, Km 10 Airport Road, Galadimawa, Abuja, Federal Capital Territory (Nigeria)

    2015-08-21

    In this paper, a combined experimental, computational, and analytical approach is used to provide new insights into the lamination of organic solar cells and light emitting devices at macro- and micro-scales. First, the effects of applied lamination force (on contact between the laminated layers) are studied. The crack driving forces associated with the interfacial cracks (at the bi-material interfaces) are estimated along with the critical interfacial crack driving forces associated with the separation of thin films, after layer transfer. The conditions for successful lamination are predicted using a combination of experiments and computational models. Guidelines are developed for the lamination of low-cost organic electronic structures.

  6. Lamination of organic solar cells and organic light emitting devices: Models and experiments

    International Nuclear Information System (INIS)

    In this paper, a combined experimental, computational, and analytical approach is used to provide new insights into the lamination of organic solar cells and light emitting devices at macro- and micro-scales. First, the effects of applied lamination force (on contact between the laminated layers) are studied. The crack driving forces associated with the interfacial cracks (at the bi-material interfaces) are estimated along with the critical interfacial crack driving forces associated with the separation of thin films, after layer transfer. The conditions for successful lamination are predicted using a combination of experiments and computational models. Guidelines are developed for the lamination of low-cost organic electronic structures

  7. Flexible organic solar cells including efficiency enhancing grating structures

    DEFF Research Database (Denmark)

    Oliveira Hansen, Roana Melina de; Liu, Yinghui; Madsen, Morten;

    2013-01-01

    In this work, a new method for the fabrication of organic solar cells containing functional light-trapping nanostructures on flexible substrates is presented. Polyimide is spin-coated on silicon support substrates, enabling standard micro- and nanotechnology fabrication techniques, such as photol......-trapping efficiency for the selected active layer material (P3HT:PCBM), resulting in an enhancement of about 34% on the solar cell efficiency. The presented method can be applied to a large variety of flexible nanostructured devices in future applications....

  8. Reversible degradation of inverted organic solar cells by concentrated sunlight

    DEFF Research Database (Denmark)

    Tromholt, Thomas; Manor, Assaf; Katz, Eugene A; Krebs, Frederik C

    2011-01-01

    cell, after 30 min exposure at 5 suns and after 30 min of rest in the dark. High intensity exposure introduced a major performance decrease for all solar intensities, followed by a partial recovery of the lost performance over time: at 1 sun only 6% of the initial performance was conserved after the....... The transient state is believed to be a result of the breakdown of the diode behaviour of the ZnO electron transport layer by O2 desorption, increasing the hole conductivity. These results imply that accelerated degradation of organic solar cells by concentrated sunlight is not a straightforward...

  9. Proteomic and phosphoproteomic analysis of signalling by adhesion and growth factor receptors in mammary epithelial cells

    OpenAIRE

    Paul, Nikki

    2014-01-01

    Cell adhesion and communication are essential for tissue morphogenesis and repair in healthy multicellular organisms. However, dysregulation of these processes can drive disease progression in conditions such as cancer. Selective cell adhesion to the extracellular matrix is mediated by integrins, a family of transmembrane receptors that compartmentalise signalling and organise the cytoskeleton. Adhesion receptors provide spatial cues to cells to allow them to respond to growth factor and cyto...

  10. Diamagnetic levitation causes changes in the morphology, cytoskeleton, and focal adhesion proteins expression in osteocytes.

    Science.gov (United States)

    Qian, A R; Wang, L; Gao, X; Zhang, W; Hu, L F; Han, J; Li, J B; Di, S M; Shang, Peng

    2012-01-01

    Diamagnetic levitation technology is a novel simulated weightless technique and has recently been applied in life-science research. We have developed a superconducting magnet platform with large gradient high magnetic field (LG-HMF), which can provide three apparent gravity levels, namely, μg (diamagnetic levitation), 1g, and 2g for diamagnetic materials. In this study, the effects of LG-HMF on the activity, morphology, and cytoskeleton (actin filament, microtubules, and vimentin intermediate filaments) in osteocyte - like cell line MLO-Y4 were detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) methods, hematoxylin-eosin (HE) staining, and laser scanning confocal microscopy (LSCM), respectively. The changes induced by LG-HMF in distribution and expression of focal adhesion (FA) proteins, including vinculin, paxillin, and talin in MLO-Y4 were determined by LSCM and Western blotting. The results showed that LG-HMF produced by superconducting magnet had no lethal effects on MLO-Y4. Compared to control, diamagnetic levitation (μg) affected MLO-Y4 morphology, nucleus size, cytoskeleton architecture, and FA proteins distribution and expression. The study indicates that osteocytes are sensitive to altered gravity and FA proteins (vinculin, paxillin, and talin) may be involved in osteocyte mechanosensation. The diamagnetic levitation may be a novel ground-based space-gravity simulator and can be used for biological experiment at cellular level. PMID:21216704

  11. Interface engineering for efficient fullerene-free organic solar cells

    International Nuclear Information System (INIS)

    We demonstrate the role of zinc oxide (ZnO) morphology and addition of an acceptor interlayer to achieve high efficiency fullerene-free bulk heterojunction inverted organic solar cells. Nanopatterning of the ZnO buffer layer enhances the effective light absorption in the active layer, and the insertion of a twisted perylene acceptor layer planarizes and decreases the electron extraction barrier. Along with an increase in current homogeneity, the reduced work function difference and selective transport of electrons prevent the accumulation of charges and decrease the electron-hole recombination at the interface. These factors enable an overall increase of efficiency to 4.6%, which is significant for a fullerene-free solution-processed organic solar cell

  12. Interface engineering for efficient fullerene-free organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Shivanna, Ravichandran; Narayan, K. S., E-mail: rajaram@jncasr.ac.in, E-mail: narayan@jncasr.ac.in [Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064 (India); Rajaram, Sridhar, E-mail: rajaram@jncasr.ac.in, E-mail: narayan@jncasr.ac.in [International Centre for Materials Science, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064 (India)

    2015-03-23

    We demonstrate the role of zinc oxide (ZnO) morphology and addition of an acceptor interlayer to achieve high efficiency fullerene-free bulk heterojunction inverted organic solar cells. Nanopatterning of the ZnO buffer layer enhances the effective light absorption in the active layer, and the insertion of a twisted perylene acceptor layer planarizes and decreases the electron extraction barrier. Along with an increase in current homogeneity, the reduced work function difference and selective transport of electrons prevent the accumulation of charges and decrease the electron-hole recombination at the interface. These factors enable an overall increase of efficiency to 4.6%, which is significant for a fullerene-free solution-processed organic solar cell.

  13. Comparison of recombination models in organic bulk heterojunction solar cells

    International Nuclear Information System (INIS)

    Recombination in bulk-heterojunction (BHJ) organic solar cells is the key loss mechanism, and it directly affects characteristic parameters such as power conversion efficiency, short-circuit current, open-circuit voltage, and fill factor. However, which recombination mechanism dominates the loss in organic materials is unclear at present. In this work, we simulate state-of-art BHJ solar cells using five recombination models, including direct recombination, Langevin recombination, charge transfer state recombination, trap-assisted recombination, and recombination via tail. All processes are strongly dependent on charge carrier mobility and exhibit a similar recombination distribution in active layer. For high mobilities, all models present a similar behavior along with the increased mobilities, whereas, there are slight differences in open-circuit voltage between trap/tail model and other ones at lower mobilities, resulting from the interaction between photo-carriers and dark-carriers

  14. Exploring Spray-Coating Techniques for Organic Solar Cell Applications

    Directory of Open Access Journals (Sweden)

    Wanyi Nie

    2012-01-01

    Full Text Available We have investigated spray coating as a novel processing method for organic solar cell fabrication. In this work, spraying parameters and organic solvent influences have been correlated with cell performance. Using airbrush fabrication, bulk heterojunction photovoltaic devices based on a new low band gap donor material: poly[(4,8-bis(1-pentylhexyloxybenzo[1,2-b:4,5-b′]dithiophene-2,6-diyl-alt-2,1,3-benzoxadiazole-4,7-diyl] with the C60-derivative (6,6-phenyl C61-butyric acid methyl ester (PCBM as an acceptor, have achieved power conversion efficiencies over 3%. We show that airbrush fabrication can be carried out with simple solvents such as pristine 1,2-dichlorobenzene. Moreover, the influence of device active area has been studied and the 1 cm2 device by spray coating maintained an excellent power conversion efficiency of 3.02% on average.

  15. Effects of radiation and chemical substances on cells and organism

    International Nuclear Information System (INIS)

    The book treats the radiation chemistry part of biophysics and applied biophysics in the sphere of ionizing radiation. Discussed are the concepts of radiation units and radioactivity units and the relative biological efficiency. The effects of ionizing and UV radiations are analyzed at the level of macromolecular changes. Chapters dealing with genetic radiation effects discuss the effects at the cellular level with respect to cell proliferation. All these problems are used to illustrate the effect on the organism as a whole. The chapters on applied biophysics deal with the indications of radiation and chemical damage, sensitivity of cells and the organism, and the study and influencing of growth at the cellular level. The concluding chapter is devoted to the environmental impact of radiation. (J.P.)

  16. Thin Film Solar Cells: Organic, Inorganic and Hybrid

    Science.gov (United States)

    Dankovich, John

    2004-01-01

    Thin film solar cells are an important developing resource for hundreds of applications including space travel. In addition to being more cost effective than traditional single crystal silicon cells, thin film multi-crystaline cells are plastic and light weight. The plasticity of the cells allows for whole solar panels to be rolled out from reams. Organic layers are being investigated in order to increase the efficiency of the cells to create an organic / inorganic hybrid cell. The main focus of the group is a thin film inorganic cell made with the absorber CuInS2. So far the group has been successful in creating the layer from a single-source precursor. They also use a unique method of film deposition called chemical vapor deposition for this. The general makeup of the cell is a molybdenum back contact with the CuInS2 layer, then CdS, ZnO and aluminum top contacts. While working cells have been produced, the efficiency so far has been low. Along with quantum dot fabrication the side project of this that is currently being studied is adding a polymer layer to increase efficiency. The polymer that we are using is P3OT (Poly(3-octylthiopene-2,5-diyll), retroregular). Before (and if) it is added to the cell, it must be understood in itself. To do this simple diodes are being constructed to begin to look at its behavior. The P3OT is spin coated onto indium tin oxide and silver or aluminum contacts are added. This method is being studied in order to find the optimal thickness of the layer as well as other important considerations that may later affect the composition of the finished solar cell. Because the sun is the most abundant renewable, energy source that we have, it is important to learn how to harness that energy and begin to move away from our other depleted non-renewable energy sources. While traditional silicon cells currently create electricity at relatively high efficiencies, they have drawbacks such as weight and rigidness that make them unattractive

  17. Single cell growth and gene expression dynamics in model organisms

    OpenAIRE

    Cookson, Natalie Anne

    2009-01-01

    The developing discipline of synthetic biology attempts to recreate in artificial systems the emergent properties found in natural biology. Progress in this field requires a thorough understanding of the basic cellular functions that underly complex biological networks. Here, we present several studies that use existing and novel methods to probe the dynamic behavior of the model organisms Saccharomyces cerevisiae and Escherichia coli at the single cell level. First, we develop a microfluidic...

  18. Planar organic-inorganic hybrid perovskite solar cell by electrospray

    OpenAIRE

    Chen, Wenjun

    2015-01-01

    Recently, the organic-inorganic perovskite solar cell has attracted great attention due to the easy processing and rapid developed power conversion efficiency. The tri-halide perovskite CH3NH3PbI3-xClx possessing excellent optical and electronic properties, such as absorption hands span the visible region, long charge carrier diffusion lengths, and appropriate direct band gap, makes them ideal active layer material for photovoltaic devices. In this thesis, electrohydrodynamic spraying is used...

  19. The Composition and Organization of Cytoplasm in Prebiotic Cells

    OpenAIRE

    Trevors, Jack T.

    2011-01-01

    This article discusses the hypothesized composition and organization of cytoplasm in prebiotic cells from a theoretical perspective and also based upon what is currently known about bacterial cytoplasm. It is unknown if the first prebiotic, microscopic scale, cytoplasm was initially contained within a primitive, continuous, semipermeable membrane, or was an uncontained gel substance, that later became enclosed by a continuous membrane. Another possibility is that the first cytoplasm in prebio...

  20. Alert cell strategy: mechanisms of inflammatory response and organ protection.

    Science.gov (United States)

    Hatakeyama, Noboru; Matsuda, Naoyuki

    2014-01-01

    Systemic inflammatory response syndrome (SIRS) is triggered by various factors such as surgical operation, trauma, burn injury, ischemia, pancreatitis and bacterial translocation. Sepsis is a SIRS associated with bacterial infection. SIRS and sepsis tend to trigger excessive production of inflammatory cytokines and other inflammatory molecules and induce multiple organ failure, such as acute lung injury, acute kidney injury and inflammatory cardiac injury. Epithelial and endothelial cells in some major organs express inflammatory receptors on the plasma membrane and work as alert cells for inflammation, and regulation of these alert cells could have a relieving effect on the inflammatory response. In inflammatory conditions, initial cardiac dysfunction is mediated by decreased preload and adequate infusion therapy is required. Tachyarrhythmia is a complication of inflammatory conditions and early control of the inflammatory reaction would prevent the structural remodeling that is resistant to therapies. Furthermore, there seems to be crosstalk between major organs with a central focus on the kidneys in inflammatory conditions. As an alert cell strategy, volatile anesthetics, sevoflurane and isoflurane, seem to have anti-inflammatory effects, and both experimental and clinical studies have shown the beneficial effects of these drugs in various settings of inflammatory conditions. On the other hand, in terms of intravenous anesthetics, propofol and ketamine, their current status is still controversial as there is a lack of confirmatory evidence on whether they have an organ-protective effect in inflammatory conditions. The local anesthetic lidocaine suppressed inflammatory responses upon both systemic and local administration. For the control of inflammatory conditions, anesthetic agents may be a target of drug development in accordance with other treatments and drugs. PMID:25229471

  1. Formins: Linking Cytoskeleton and Endomembranes in Plant Cells

    Czech Academy of Sciences Publication Activity Database

    Cvrčková, F.; Oulehlová, Denisa; Žárský, Viktor

    2015-01-01

    Roč. 16, č. 1 (2015), s. 1-18. E-ISSN 1422-0067 Institutional support: RVO:61389030 Keywords : formin * actin * microtubules Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.862, year: 2014

  2. Molecular Understanding of Organic Solar Cells: The Challenges

    KAUST Repository

    Brédas, Jean-Luc

    2009-11-17

    (Figure presented) Our objective in this Account is 3-fold. First, we provide an overview of the optical and electronic processes that take place in a solid-state organic solar cell, which we define as a cell in which the semiconducting materials between the electrodes are organic, be them polymers, oligomers, or small molecules; this discussion is also meant to set the conceptual framework in which many of the contributions to this Special Issue on Photovoltaics can We viewed. We successively turn our attention to (i) optical absorption and exciton formation, (ii) exciton migration to the donor - acceptor interface, (iii) exciton dissociation into charge carriers, resulting in the appearance of holes in the donor and electrons in the acceptor, (iv) charge-carrier mobility, and (v) charge collection at the electrodes. For each of these processes, we also describe the theoretical challenges that need to be overcome to gain a comprehensive understanding at the molecular level. Finally, we highlight recent theoretical advances, in particular regarding the determination of the energetics and dynamics at organic - organic interfaces, and underline that the right balance needs to be found for the optimization of material parameters that often result in opposite effects on the photovoltaic performance. © 2009 American Chemical Society.

  3. Coding and traceability for cells, tissues and organs for transplantation.

    Science.gov (United States)

    Strong, D Michael; Shinozaki, Naoshi

    2010-11-01

    Modern transplantation of cells, tissues and organs has been practiced within the last century achieving both life saving and enhancing results. Associated risks have been recognized including infectious disease transmission, malignancy, immune mediated disease and graft failure. This has resulted in establishment of government regulation, professional standard setting and establishment of vigilance and surveillance systems for early detection and prevention and to improve patient safety. The increased transportation of grafts across national boundaries has made traceability difficult and sometimes impossible. Experience during the first Gulf War with mis-identification of blood units coming from multiple countries without standardized coding and labeling has led international organizations to develop standardized nomenclature and coding for blood. Following this example, cell therapy and tissue transplant practitioners have also moved to standardization of coding systems. Establishment of an international coding system has progressed rapidly and implementation for blood has demonstrated multiple advantages. WHO has held two global consultations on human cells and tissues for transplantation, which recognized the global circulation of cells and tissues and growing commercialization and the need for means of coding to identify tissues and cells used in transplantation, are essential for full traceability. There is currently a wide diversity in the identification and coding of tissue and cell products. For tissues, with a few exceptions, product terminology has not been standardized even at the national level. Progress has been made in blood and cell therapies with a slow and steady trend towards implementation of the international code ISBT 128. Across all fields, there are now 3,700 licensed facilities in 66 countries. Efforts are necessary to encourage the introduction of a standardized international coding system for donation identification numbers, such as ISBT

  4. APPLICATION OF STEM CELLS AND PRECURSOR CELLS FOR STIMULATION OF ORGAN REVASCULARIZATION AND REGENERATION

    Directory of Open Access Journals (Sweden)

    M. V. Eremeeva

    2010-01-01

    Full Text Available Different angiogenic factors induced angiogenesis stimulation in ischemic tissues stays in the focus of scientific research for long time. The key role in ischemic angiogenesis belongs to endothelial precursor cells, plenty of which are reserved in bone marrow. Resident endothelial precursor cells are also found in some tissues and in circulation. These cells are involved in neoangiogenesis as well. Theoretically, injection of exogeneous endothelial precusor cells might contribute to restoration of circulation in the ischemic organ. Various types of cells have been approved for regeneration stimulation in a number of experimental protocols. A various degree of improvement of myocardial contractive function has been obtained as a universal result of these investigations, though the mechanisms underlying observed effect remain evasive. The paper focuses on advantages and drawbacks of embryonic, hematopoetic and mesenhimal stem cells application for angiogenesis stimulation and organs and tissues regeneration. 

  5. Cell shape and spreading of stromal (mesenchymal) stem cells cultured on fibronectin coated gold and hydroxyapatite surfaces

    DEFF Research Database (Denmark)

    Dolatshahi-Pirouz, A; Jensen, Thomas Hartvig Lindkjær; Kolind, Kristian;

    2011-01-01

    concentration. In subsequent cell studies with hMSC's we studied the cell spreading, cytoskeletal organization and cell morphology on the respective surfaces. When the cells were adsorbed on the uncoated substrates, a diffuse cell actin cytoskeleton was revealed, and the cells had a highly elongated shape. On...... observed on HA as compared to Au. Moreover, the results revealed that the morphology of cells cultured on fibronectin coated HA surfaces were less irregular. In summary we find that fibronectin adsorbs in a more activated state on the HA surfaces, resulting in a slightly different cellular response as...

  6. In situ spectroscopy and characterisation of organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Holch, F.; Pernpeintner, J.; Schoell, A.; Umbach, E. [Universitaet Wuerzburg, Experimentelle Physik II, 97074 Wuerzburg (Germany)

    2007-07-01

    Electronic devices based on organic semiconductors belong to a field of growing interest in fundamental and application related research. The different experimental methods and preparation techniques often complicate a comprehensive understanding of fundamental properties and their impact on device performance. We present first results from a new project focussing on organic solar cells using relatively small organic molecules. For a better understanding of the limiting parameters basic questions such as the determination of energy levels in the active layer as well as the bandoffsets/-alignment at the organic hetero-interface and contacts will be addressed using photoelectron spectroscopy (UPS) and inverse photoelectron spectroscopy (IPES). In situ electrical measurements (IV) help to associate fundamental results with device characteristics such as efficiency and fill factor. In order to avoid uncontrolled contamination, the complete fabrication (active layer and contacts) and characterisation is performed under clean and well defined conditions in UHV. As a benefit of this approach the influence of contamination occurring, e.g., during the fabrication process or device operation can be analysed systematically. Moreover, metal deposition methods are optimised in order to reduce damage to the sensitive organic layer.

  7. MreBCD-associated Cytoskeleton is Required for Proper Segregation of the Chromosomal Terminus during the Division Cycle of Escherichia Coli

    Institute of Scientific and Technical Information of China (English)

    Yu-Jia Huo; Ling Qiao; Xiao-Wei Zheng; Cheng Cui; Yuan-Fang Ma; Feng Lu

    2015-01-01

    Background:In prokaryotic organisms,the mechanism responsible for the accurate partition of newly replicated chromosomes into daughter cells is incompletely understood.Segregation of the replication terminus of the circular prokaryotic chromosome poses special problems that have not previously been addressed.The aim of this study was to investigate the roles of several protein components (MreB,MreC,and MreD) of the prokaryotic cytoskeleton for the faithful transmission of the chromosomal terminus into daughter cells.Methods:Strain LQ1 (mreB::cat),LQ2 (mreC::cat),and LQ3 (mreD::cat) were constructed using the Red recombination system.LQ11/pLAU53,LQ12/pLAU53,LQ13/pLAU53,LQ14/pLAU53,and LQ15/pLAU53 strains were generated by Pltransduction of (tetO)240-Gm and (lacO)240-Km cassettes from strains IL2 and IL29.Fluorescence microscopy was performed to observe localization pattern of fluorescently-labeled origin and terminus foci in wild-type and mutant cells.SOS induction was monitored as gfp fluorescence from PsulA-gfp in log phase cells grown in Luria-Bertani medium at 37℃ by measurement of emission at 525 nm with excitation at 470 nm in a microplate fluorescence reader.Results:Mutational deletion of the mreB,mreC,or mreD genes was associated with selective loss of the terminus region in approximately 40% of the cells within growing cultures.This was accompanied by significant induction of the SOS DNA damage response,suggesting that deletion of terminus sequences may have occurred by chromosomal cleavage,presumably caused by ingrowth of the division septum prior to segregation of the replicated terminal.Conclusions:These results imply a role for the MreBCD cytoskeleton in the resolution of the final products of terminus replication and/ or in the specific movement of newly replicated termini away from midcell prior to completion of septal ingrowth.This would identify a previously unrecognized stage in the overall process of chromosome segregation.

  8. Understanding organic photovoltaic cells: Electrode, nanostructure, reliability, and performance

    Science.gov (United States)

    Kim, Myung-Su

    My Ph.D. research has focused on alternative renewable energy using organic semiconductors. During my study, first, I have established reliable characterization methods of organic photovoltaic devices. More specifically, less than 5% variation of power conversion efficiency of fabricated organic blend photovoltaic cells (OBPC) was achieved after optimization. The reproducibility of organic photovoltaic cell performance is one of the essential issues that must be clarified before beginning serious investigations of the application of creative and challenging ideas. Second, the relationships between fill factor (FF) and process variables have been demonstrated with series and shunt resistance, and this provided a chance to understand the electrical device behavior. In the blend layer, series resistance (Rs) and shunt resistance (Rsh) were varied by controlling the morphology of the blend layer, the regioregularity of the conjugated polymer, and the thickness of the blend layer. At the interface between the cathode including PEDOT:PSS and the blend layer, cathode conductivity was controlled by varying the structure of the cathode or adding an additive. Third, we thoroughly examined possible characterization mistakes in OPVC. One significant characterization mistake is observed when the crossbar electrode geometry of OPVC using PEDOT:PSS was fabricated and characterized with illumination which is larger than the actual device area. The hypothesis to explain this overestimation was excess photo-current generated from the cell region outside the overlapped electrode area, where PEDOT:PSS plays as anode and this was clearly supported with investigations. Finally, I incorporated a creative idea, which enhances the exciton dissociation efficiency by increasing the interface area between donor and acceptor to improve the power conversion efficiency of organic photovoltaic cells. To achieve this, nanoimprint lithography was applied for interface area increase. To clarify the

  9. The functional organization of mitochondrial genomes in human cells

    Directory of Open Access Journals (Sweden)

    Kimura Hiroshi

    2004-05-01

    Full Text Available Abstract Background We analyzed the organization and function of mitochondrial DNA in a stable human cell line (ECV304, which is also known as T-24 containing mitochondria tagged with the yellow fluorescent protein. Results Mitochondrial DNA is organized in ~475 discrete foci containing 6–10 genomes. These foci (nucleoids are tethered directly or indirectly through mitochondrial membranes to kinesin, marked by KIF5B, and microtubules in the surrounding cytoplasm. In living cells, foci have an apparent diffusion constant of 1.1 × 10-3 μm2/s, and mitochondria always split next to a focus to distribute all DNA to one daughter. The kinetics of replication and transcription (monitored by immunolabelling after incorporating bromodeoxyuridine or bromouridine reveal that each genome replicates independently of others in a focus, and that newly-made RNA remains in a focus (residence half-time ~43 min long after it has been made. This mitochondrial RNA colocalizes with components of the cytoplasmic machinery that makes and imports nuclear-encoded proteins – that is, a ribosomal protein (S6, a nascent peptide associated protein (NAC, and the translocase in the outer membrane (Tom22. Conclusions The results suggest that clusters of mitochondrial genomes organize the translation machineries on both sides of the mitochondrial membranes. Then, proteins encoded by the nuclear genome and destined for the mitochondria will be made close to mitochondrial-encoded proteins so that they can be assembled efficiently into mitochondrial complexes.

  10. Characterization of organic photovoltaic cells in comparison with analytic simulations

    Energy Technology Data Exchange (ETDEWEB)

    Koerner, Christian [Universitaet Wuerzburg (Germany). Experimentelle Physik VI; Universitaet Wuerzburg (Germany). Experimentelle Physik II; Holch, Florian; Schoell, Achim; Reinert, Friedrich [Universitaet Wuerzburg (Germany). Experimentelle Physik II; Deibel, Carsten; Dyakonov, Vladimir [Universitaet Wuerzburg (Germany). Experimentelle Physik VI

    2008-07-01

    Electronic devices based on organic semiconductors receive a growing interest in fundamental and application related research. One reason is that organic thin film photovoltaic cells promise to offer a cost- and resource-efficient fabrication. In order to achieve higher efficiencies it is indispensable to better understand the fundamental processes within the solar cell and at the interfaces, such as charge-carrier generation, separation and transport. The samples, composed of copper-phthalocyanine (CuPc) and C{sub 60} layers and sandwiched between an ITO-coated glass substrate and metal electrodes, are prepared via organic molecular beam deposition under clean and well defined conditions in ultra high vacuum. By in-situ measurements of the current-voltage characteristics, the influence of incident light power, temperature, and cathode material can be investigated in detail. The experimental results are discussed in comparison to an analytical simulation of the open-circuit voltage, in view of different models for the charge carrier injection at the electrodes.

  11. Par-4-mediated recruitment of Amida to the actin cytoskeleton leads to the induction of apoptosis

    International Nuclear Information System (INIS)

    Par-4 (prostate apoptosis response-4) sensitizes cells to apoptotic stimuli, but the exact mechanisms are still poorly understood. Using Par-4 as bait in a yeast two-hybrid screen, we identified Amida as a novel interaction partner, a ubiquitously expressed protein which has been suggested to be involved in apoptotic processes. Complex formation of Par-4 and Amida occurs in vitro and in vivo and is mediated via the C-termini of both proteins, involving the leucine zipper of Par-4. Amida resides mainly in the nucleus but displays nucleo-cytoplasmic shuttling in heterokaryons. Upon coexpression with Par-4 in REF52.2 cells, Amida translocates to the cytoplasm and is recruited to actin filaments by Par-4, resulting in enhanced induction of apoptosis. The synergistic effect of Amida/Par-4 complexes on the induction of apoptosis is abrogated when either Amida/Par-4 complex formation or association of these complexes with the actin cytoskeleton is impaired, indicating that the Par-4-mediated relocation of Amida to the actin cytoskeleton is crucial for the pro-apoptotic function of Par-4/Amida complexes in REF52.2 cells. The latter results in enhanced phosphorylation of the regulatory light chain of myosin II (MLC) as has previously been shown for Par-4-mediated recruitment of DAP-like kinase (Dlk), suggesting that the recruitment of nuclear proteins involved in the regulation of apoptotic processes to the actin filament system by Par-4 represents a potent mechanism how Par-4 can trigger apoptosis

  12. Fluxes of water through aquaporin 9 weaken membrane-cytoskeleton anchorage and promote formation of membrane protrusions.

    Directory of Open Access Journals (Sweden)

    Thommie Karlsson

    Full Text Available All modes of cell migration require rapid rearrangements of cell shape, allowing the cell to navigate within narrow spaces in an extracellular matrix. Thus, a highly flexible membrane and a dynamic cytoskeleton are crucial for rapid cell migration. Cytoskeleton dynamics and tension also play instrumental roles in the formation of different specialized cell membrane protrusions, viz. lamellipodia, filopodia, and membrane blebs. The flux of water through membrane-anchored water channels, known as aquaporins (AQPs has recently been implicated in the regulation of cell motility, and here we provide novel evidence for the role of AQP9 in the development of various forms of membrane protrusion. Using multiple imaging techniques and cellular models we show that: (i AQP9 induced and accumulated in filopodia, (ii AQP9-associated filopodial extensions preceded actin polymerization, which was in turn crucial for their stability and dynamics, and (iii minute, local reductions in osmolarity immediately initiated small dynamic bleb-like protrusions, the size of which correlated with the reduction in osmotic pressure. Based on this, we present a model for AQP9-induced membrane protrusion, where the interplay of water fluxes through AQP9 and actin dynamics regulate the cellular protrusive and motile activity of cells.

  13. Organic electrochemical transistors for cell-based impedance sensing

    Energy Technology Data Exchange (ETDEWEB)

    Rivnay, Jonathan, E-mail: rivnay@emse.fr, E-mail: owens@emse.fr; Ramuz, Marc; Hama, Adel; Huerta, Miriam; Owens, Roisin M., E-mail: rivnay@emse.fr, E-mail: owens@emse.fr [Department of Bioelectronics, Ecole des Mines de St. Etienne, 13541 Gardanne (France); Leleux, Pierre [Department of Bioelectronics, Ecole des Mines de St. Etienne, 13541 Gardanne (France); Microvitae Technologies, Pole d' Activite Y. Morandat, 13120 Gardanne (France)

    2015-01-26

    Electrical impedance sensing of biological systems, especially cultured epithelial cell layers, is now a common technique to monitor cell motion, morphology, and cell layer/tissue integrity for high throughput toxicology screening. Existing methods to measure electrical impedance most often rely on a two electrode configuration, where low frequency signals are challenging to obtain for small devices and for tissues with high resistance, due to low current. Organic electrochemical transistors (OECTs) are conducting polymer-based devices, which have been shown to efficiently transduce and amplify low-level ionic fluxes in biological systems into electronic output signals. In this work, we combine OECT-based drain current measurements with simultaneous measurement of more traditional impedance sensing using the gate current to produce complex impedance traces, which show low error at both low and high frequencies. We apply this technique in vitro to a model epithelial tissue layer and show that the data can be fit to an equivalent circuit model yielding trans-epithelial resistance and cell layer capacitance values in agreement with literature. Importantly, the combined measurement allows for low biases across the cell layer, while still maintaining good broadband signal.

  14. Organic electrochemical transistors for cell-based impedance sensing

    Science.gov (United States)

    Rivnay, Jonathan; Ramuz, Marc; Leleux, Pierre; Hama, Adel; Huerta, Miriam; Owens, Roisin M.

    2015-01-01

    Electrical impedance sensing of biological systems, especially cultured epithelial cell layers, is now a common technique to monitor cell motion, morphology, and cell layer/tissue integrity for high throughput toxicology screening. Existing methods to measure electrical impedance most often rely on a two electrode configuration, where low frequency signals are challenging to obtain for small devices and for tissues with high resistance, due to low current. Organic electrochemical transistors (OECTs) are conducting polymer-based devices, which have been shown to efficiently transduce and amplify low-level ionic fluxes in biological systems into electronic output signals. In this work, we combine OECT-based drain current measurements with simultaneous measurement of more traditional impedance sensing using the gate current to produce complex impedance traces, which show low error at both low and high frequencies. We apply this technique in vitro to a model epithelial tissue layer and show that the data can be fit to an equivalent circuit model yielding trans-epithelial resistance and cell layer capacitance values in agreement with literature. Importantly, the combined measurement allows for low biases across the cell layer, while still maintaining good broadband signal.

  15. Bulk-heterojunction organic solar cells based on merocyanine colorants

    Energy Technology Data Exchange (ETDEWEB)

    Kronenberg, Nils M.; Lademann, Hans W.A.; Meerholz, Klaus [Department fuer Chemie, Universitaet zu Koen (Germany); Buerckstuemmer, Hannah; Tulyakova, Elena V.; Deppisch, Manuela; Wuerthner, Frank [Institut fuer Organische Chemie, Universitaet Wuerzburg (Germany)

    2009-07-01

    To take advantage of the full potential of organic Bulk Heterojunction (BHJ) solar cells, there is a need to explore new materials. We introduced merocyanines dyes (MCs) as a new class of electron donor materials for the application in solution-processed BHJ solar cells. MCs are traditional low-molecular colorants that are widely applied in textile coloration, for printing purposes, and nonlinear optics. Due to their structure, consisting of an electron-donating and an electron-accepting subunit, they possess high absorption coefficients which is favorable for the use in solar cells. The vast variety of the MC synthesis allows for a variation of the absorption properties in a wide range and a tuning of the solar cell absorption to the emission spectrum of the sun. Another advantage of MCs compared to some long-wavelength absorbing polymers is the relatively low HOMO-energy (down to -6.0 eV), which is beneficial for large open-circuit voltages. We tested various different MC-dyes in the application as donor compound in BHJ solar cells in combination with the soluble C{sub 60} derivative PCBM. Power conversion efficiencies up to 2.1% under standard illumination and 2.7% at reduced intensities were achieved.

  16. The ubiquitin C-terminal hydrolase UCH-L1 promotes bacterial invasion by altering the dynamics of the actin cytoskeleton

    DEFF Research Database (Denmark)

    Basseres, Eugene; Coppotelli, Giuseppe; Pfirrmann, Thorsten;

    2010-01-01

    Invasion of eukaryotic target cells by pathogenic bacteria requires extensive remodelling of the membrane and actin cytoskeleton. Here we show that the remodelling process is regulated by the ubiquitin C-terminal hydrolase UCH-L1 that promotes the invasion of epithelial cells by Listeria monocyto...... findings highlight a previously unrecognized involvement of the ubiquitin cycle in bacterial entry. UCH-L1 is highly expressed in malignant cells that may therefore be particularly susceptible to invasion by bacteria-based drug delivery systems.......Invasion of eukaryotic target cells by pathogenic bacteria requires extensive remodelling of the membrane and actin cytoskeleton. Here we show that the remodelling process is regulated by the ubiquitin C-terminal hydrolase UCH-L1 that promotes the invasion of epithelial cells by Listeria...

  17. Photodynamic therapy for basal cell skin cancer ENT-organs

    Directory of Open Access Journals (Sweden)

    V. N. Volgin

    2014-01-01

    Full Text Available Results of photodynamic therapy in 96 patients with primary and recurrent basal cell skin cancer of ENT-organs are represented. For photodynamic therapy the Russian-made photosensitizer Photoditazine at dose of 0.6–1.4 mg/kg was used. Parameters were selected taking into account type and extent of tumor and were as follows: output power – 0.1–3.0 W, power density – 0.1–1.3 W/cm2, light dose – 100–400 J/cm2. The studies showed high efficacy of treatment for primary and recurrent basal cell skin cancer of nose, ear and external auditory canal – from 87.5 to 94.7% of complete regression. Examples of efficacy of the method are represented in the article. High efficacy and good cosmetic effects allowed to make a conclusion about perspectivity of photodynamic therapy for recurrent basal cell skin cancer of ENT-organs

  18. Directing cell migration and organization via nanocrater-patterned cell-repellent interfaces

    Science.gov (United States)

    Jeon, Hojeong; Koo, Sangmo; Reese, Willie Mae; Loskill, Peter; Grigoropoulos, Costas P.; Healy, Kevin E.

    2015-09-01

    Although adhesive interactions between cells and nanostructured interfaces have been studied extensively, there is a paucity of data on how nanostructured interfaces repel cells by directing cell migration and cell-colony organization. Here, by using multiphoton ablation lithography to pattern surfaces with nanoscale craters of various aspect ratios and pitches, we show that the surfaces altered the cells’ focal-adhesion size and distribution, thus affecting cell morphology, migration and ultimately localization. We also show that nanocrater pitch can disrupt the formation of mature focal adhesions to favour the migration of cells towards higher-pitched regions, which present increased planar area for the formation of stable focal adhesions. Moreover, by designing surfaces with variable pitch but constant nanocrater dimensions, we were able to create circular and striped cellular patterns. Our surface-patterning approach, which does not involve chemical treatments and can be applied to various materials, represents a simple method to control cell behaviour on surfaces.

  19. Structural templating of multiple polycrystalline layers in organic photovoltaic cells

    Energy Technology Data Exchange (ETDEWEB)

    Lassiter, Brian E; Lunt, Richard R; Renshaw, Kyle; Forrest, Stephen R.

    2010-09-01

    We demonstrate that organic photovoltaic cell performance is influenced by changes in the crystalline orientation of composite layer structures. A 1.5 nm thick self-organized, polycrystalline template layer of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) orients subsequently deposited layers of a diindenoperylene exciton blocking layer, and the donor, copper phthalocyanine (CuPc). Control over the crystalline orientation of the CuPc leads to changes in its frontier energy levels, absorption coefficient, and surface morphology, resulting in an increase of power conversion efficiency at 1 sun from 1.42 ± 0.04% to 2.19 ± 0.05% for a planar heterojunction and from 1.89 ± 0.05% to 2.49 ± 0.03% for a planar-mixed heterojunction.

  20. Structural templating of multiple polycrystalline layers in organic photovoltaic cells.

    Science.gov (United States)

    Lassiter, Brian E; Lunt, Richard R; Renshaw, C Kyle; Forrest, Stephen R

    2010-09-13

    We demonstrate that organic photovoltaic cell performance is influenced by changes in the crystalline orientation of composite layer structures. A 1.5 nm thick self-organized, polycrystalline template layer of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) orients subsequently deposited layers of a diindenoperylene exciton blocking layer, and the donor, copper phthalocyanine (CuPc). Control over the crystalline orientation of the CuPc leads to changes in its frontier energy levels, absorption coefficient, and surface morphology, resulting in an increase of power conversion efficiency at 1 sun from 1.42 ± 0.04% to 2.19 ± 0.05% for a planar heterojunction and from 1.89 ± 0.05% to 2.49 ± 0.03% for a planar-mixed heterojunction. PMID:21165074

  1. An overview of molecular acceptors for organic solar cells

    Directory of Open Access Journals (Sweden)

    Hudhomme Piétrick

    2013-07-01

    Full Text Available Organic solar cells (OSCs have gained serious attention during the last decade and are now considered as one of the future photovoltaic technologies for low-cost power production. The first dream of attaining 10% of power coefficient efficiency has now become a reality thanks to the development of new materials and an impressive work achieved to understand, control and optimize structure and morphology of the device. But most of the effort devoted to the development of new materials concerned the optimization of the donor material, with less attention for acceptors which to date remain dominated by fullerenes and their derivatives. This short review presents the progress in the use of non-fullerene small molecules and fullerene-based acceptors with the aim of evaluating the challenge for the next generation of acceptors in organic photovoltaics.

  2. The bacterial cytoskeleton modulates motility, type 3 secretion, and colonization in Salmonella.

    Directory of Open Access Journals (Sweden)

    David M Bulmer

    2012-01-01

    Full Text Available Although there have been great advances in our understanding of the bacterial cytoskeleton, major gaps remain in our knowledge of its importance to virulence. In this study we have explored the contribution of the bacterial cytoskeleton to the ability of Salmonella to express and assemble virulence factors and cause disease. The bacterial actin-like protein MreB polymerises into helical filaments and interacts with other cytoskeletal elements including MreC to control cell-shape. As mreB appears to be an essential gene, we have constructed a viable ΔmreC depletion mutant in Salmonella. Using a broad range of independent biochemical, fluorescence and phenotypic screens we provide evidence that the Salmonella pathogenicity island-1 type three secretion system (SPI1-T3SS and flagella systems are down-regulated in the absence of MreC. In contrast the SPI-2 T3SS appears to remain functional. The phenotypes have been further validated using a chemical genetic approach to disrupt the functionality of MreB. Although the fitness of ΔmreC is reduced in vivo, we observed that this defect does not completely abrogate the ability of Salmonella to cause disease systemically. By forcing on expression of flagella and SPI-1 T3SS in trans with the master regulators FlhDC and HilA, it is clear that the cytoskeleton is dispensable for the assembly of these structures but essential for their expression. As two-component systems are involved in sensing and adapting to environmental and cell surface signals, we have constructed and screened a panel of such mutants and identified the sensor kinase RcsC as a key phenotypic regulator in ΔmreC. Further genetic analysis revealed the importance of the Rcs two-component system in modulating the expression of these virulence factors. Collectively, these results suggest that expression of virulence genes might be directly coordinated with cytoskeletal integrity, and this regulation is mediated by the two-component system

  3. Highly stable organic fluorescent nanorods for living- cell imaging

    Institute of Scientific and Technical Information of China (English)

    Minhuan Lan[1,3; Jinfeng Zhang[1,3; Xiaoyue Zhu[1; Pengfei Wang[2; Xianfeng Chen[1; Chun-Sing Lee[1; Wenjun Zhang[1

    2015-01-01

    Metal-free, organic-dye-based fluorescent nanorods were fabricated through a simple solvent-exchange procedure. The as-prepared nanorods exhibit low toxicity to living cells and excellent photostability. Furthermore, they are stable in solutions of various pHs and high ionic strength and in solutions with interfering metal ions. Compared with the free DPP-Br molecules in THF, these nanorods exhibit larger Stokes shift, broader absorption spectra, and greatly improved photostability. We successfully demonstrated the application of the nanorods, including their aforementioned beneficial characteristics, as a good fluorescence probe for bio-imaging.

  4. Photo electrochemical and organic-based solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, N.S. [California Institute of Technology, Pasadena, CA (United States); Kamat, P. [Univ. of Notre Dame, IN (United States); Spitler, M. [Boston Univ., MA (United States)

    1996-09-01

    Research in solar photoconversion has resulted in significant advances in the fields of photoelectrochemistry and dye-sensitized solar cells. Progress is also evident in the understanding of solid state organic systems for energy transduction. It is evident, however, that the examination in this report of the accomplishments in these areas serves to highlight the great extent of research that is necessary to establish a technology base sufficient for practical application. Recommendations are made in this report on the directions that this research should take.

  5. The Critical Role of the Cytoskeleton in the Pathogenesis of Giardia

    Science.gov (United States)

    Nosala, Christopher

    2016-01-01

    Giardia lamblia is a flagellated parasite of the gut and causes significant morbidity worldwide. Novel druggable targets are sorely needed due to Giardia’s prevalence and the growing threat of antibiotic resistance. Giardia’s conserved and unique cytoskeletal features, such as its eight flagella and ventral disc, are required for host colonization by facilitating motility, attachment, and cell division. Therapies that target these processes could interfere with trophozoite colonization, reduce the time or severity of the infection, and reduce the number of infectious cysts shed into the environment. This requires vetting and prioritizing critical cellular processes and identifying specific Giardia proteins in those processes as targets. It is time to leverage the wealth of data gathered through genome sequencing and proteomic studies, and new insights on the cytoskeleton of Giardia to design effective new drugs to treat giardiasis. PMID:27347476

  6. The cytoskeleton of chondrocytes of Sepia officinalis (Mollusca, Cephalopoda: an immunocytochemical study

    Directory of Open Access Journals (Sweden)

    F Leone

    2009-06-01

    Full Text Available Our previous electron microscope study showed that chondrocytes from cephalopod cartilage possess a highly developed cytoskeleton and numerous cytoplasmic processes that ramify extensively through the tissue. We have now carried out a light microscope immunocytochemical study of chondrocytes from the orbital cartilage of Sepia officinalis to obtain indications as to the nature of the cytoskeletal components. We found clear positivity to antibodies against mammalian tubulin, vimentin, GFAP, and actin, but not keratin. The simultaneous presence of several cytoskeletal components is consistent with the hypothesis that cephalopod chondrocytes have the characteristics of both chondrocytes and osteocytes of vertebrates, which endow the tissue as a whole with some of the properties of vertebrate bone. We confirm, therefore, the presence in molluscs of the ubiquitous cytoskeletal proteins of metazoan cells that have remained highly conserved throughout phylogenetic evolution.

  7. Cell-Culture Reactor Having a Porous Organic Polymer Membrane

    Science.gov (United States)

    Koontz, Steven L. (Inventor)

    2000-01-01

    A method for making a biocompatible polymer article using a uniform atomic oxygen treatment is disclosed. The substrate may be subsequently optionally grated with a compatibilizing compound. Compatibilizing compounds may include proteins, phosphory1choline groups, platelet adhesion preventing polymers, albumin adhesion promoters, and the like. The compatibilized substrate may also have a living cell layer adhered thereto. The atomic oxygen is preferably produced by a flowing afterglow microwave discharge, wherein the substrate resides in a sidearm out of the plasma. Also, methods for culturing cells for various purposes using the various membranes are disclosed as well. Also disclosed are porous organic polymers having a distributed pore chemistry (DPC) comprising hydrophilic and hydrophobic regions, and a method for making the DPC by exposing the polymer to atomic oxygen wherein the rate of hydrophilization is greater than the rate of mass loss.

  8. Fullerene derivatives as electron donor for organic photovoltaic cells

    International Nuclear Information System (INIS)

    We demonstrated the performance of unconventional, all-fullerene-based, planar heterojunction (PHJ) organic photovoltaic (OPV) cells using fullerene derivatives indene-C60 bisadduct (ICBA) and phenyl C61-butyric acid methyl ester as the electron donors with fullerene C70 as the electron acceptor. Two different charge generation processes, including charge generation in the fullerene bulk and exciton dissociation at the donor-acceptor interface, have been found to exist in such all-fullerene-based PHJ cells and the contribution to the total photocurrent from each process is strongly dependent on the thickness of fullerene donor. The optimized 5 nm ICBA/40 nm C70 PHJ cell gives clear external quantum efficiency responses for the long-wavelength photons corresponding to the dissociation of strongly bound Frenkel excitons, which is hardly observed in fullerene-based single layer reference devices. This approach using fullerene as a donor material provides further possibilities for developing high performance OPV cells

  9. 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

  10. Multiple CaMKII Binding Modes to the Actin Cytoskeleton Revealed by Single-Molecule Imaging.

    Science.gov (United States)

    Khan, Shahid; Conte, Ianina; Carter, Tom; Bayer, K Ulrich; Molloy, Justin E

    2016-07-26

    Localization of the Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) to dendritic spine synapses is determined in part by the actin cytoskeleton. We determined binding of GFP-tagged CaMKII to tag-RFP-labeled actin cytoskeleton within live cells using total internal reflection fluorescence microscopy and single-molecule tracking. Stepwise photobleaching showed that CaMKII formed oligomeric complexes. Photoactivation experiments demonstrated that diffusion out of the evanescent field determined the track lifetimes. Latrunculin treatment triggered a coupled loss of actin stress fibers and the colocalized, long-lived CaMKII tracks. The CaMKIIα (α) isoform, which was previously thought to lack F-actin interactions, also showed binding, but this was threefold weaker than that observed for CaMKIIβ (β). The βE' splice variant bound more weakly than α, showing that binding by β depends critically on the interdomain linker. The mutations βT287D and αT286D, which mimic autophosphorylation states, also abolished F-actin binding. Autophosphorylation triggers autonomous CaMKII activity, but does not impair GluN2B binding, another important synaptic protein interaction of CaMKII. The CaMKII inhibitor tatCN21 or CaMKII mutations that inhibit GluN2B association by blocking binding of ATP (βK43R and αK42M) or Ca(2+)/calmodulin (βA303R) had no effect on the interaction with F-actin. These results provide the first rationale for the reduced synaptic spine localization of the αT286D mutant, indicating that transient F-actin binding contributes to the synaptic localization of the CaMKIIα isoform. The track lifetime distributions had a stretched exponential form consistent with a heterogeneously diffusing population. This heterogeneity suggests that CaMKII adopts different F-actin binding modes, which is most easily rationalized by multiple subunit contacts between the CaMKII dodecamer and the F-actin cytoskeleton that stabilize the initial weak (micromolar

  11. Protein micro patterned lattices to probe a fundamental lengthscale involved in cell adhesion

    CERN Document Server

    Guillou, Herve; Chaussy, Jacques; Block, Marc R

    2009-01-01

    Cell adhesion, a fundamental process of cell biology is involved in the embryo development and in numerous pathologies especially those related to cancers. We constrained cells to adhere on extracellular matrix proteins patterned in a micro lattices. The actin cytoskeleton is particularly sensitive to this constraint and reproducibly self organizes in simple geometrical patterns. Such highly organized cells are functional and proliferate. We performed statistical analysis of spread cells morphologies and discuss the existence of a fundamental lengthscale associated with active processes required for spreading.

  12. Regeneration of Tissues and Organs Using Autologous Cells

    Energy Technology Data Exchange (ETDEWEB)

    Anthony Atala, M D

    2012-10-11

    The proposed work aims to address three major challenges to the field of regenerative medicine: 1) the growth and expansion of regenerative cells outside the body in controlled in vitro environments, 2) supportive vascular supply for large tissue engineered constructs, and 3) interactive biomaterials that can orchestrate tissue development in vivo. Toward this goal, we have engaged a team of scientists with expertise in cell and molecular biology, physiology, biomaterials, controlled release, nanomaterials, tissue engineering, bioengineering, and clinical medicine to address all three challenges. This combination of resources, combined with the vast infrastructure of the WFIRM, have brought to bear on projects to discover and test new sources of autologous cells that can be used therapeutically, novel methods to improve vascular support for engineered tissues in vivo, and to develop intelligent biomaterials and bioreactor systems that interact favorably with stem and progenitor cells to drive tissue maturation. The Institute's ongoing programs are aimed at developing regenerative medicine technologies that employ a patient's own cells to help restore or replace tissue and organ function. This DOE program has provided a means to solve some of the vexing problems that are germane to many tissue engineering applications, regardless of tissue type or target disease. By providing new methods that are the underpinning of tissue engineering, this program facilitated advances that can be applied to conditions including heart disease, diabetes, renal failure, nerve damage, vascular disease, and cancer, to name a few. These types of conditions affect millions of Americans at a cost of more than $400 billion annually. Regenerative medicine holds the promise of harnessing the body's own power to heal itself. By addressing the fundamental challenges of this field in a comprehensive and focused fashion, this DOE program has opened new opportunities to treat

  13. Ultrastructure of organic cell walls in Proterozoic microalgae

    Science.gov (United States)

    Moczydlowska-Vidal, M.

    2009-04-01

    The antiquity of life has been well appreciated since the discoveries of microfossils and confirmation of their authenticity, as well as the recognition of geochemical signs of biogenicity in the Archean successions. Resolving the biological affinities of early biota is essential for the unravelling the changes that led to modern biodiversity, but also for the detection of possible biogenic records outside of the terrestrial biosphere. Advanced techniques in microscopy, tomography and spectroscopy applied to examine individual microfossils at the highest attainable spatial resolution have provided unprecedented insights into micro- and nano-scale structure and composition of organic matter. Transmission and scanning electron microscopy studies of the wall ultrastructure of sphaeromorphic and ornamented acritarchs have revealed complex, single to multilayered walls, having a unique texture in sub-layers and an occasionally preserved trilaminar sheath structure (TLS) of the cell wall. A variety of optical characteristics, the electron density and texture of fabrics of discrete layers, and the properties of biopolymers may indicate the polyphyletic affiliations of such microfossils and/or the preservation of various stages (vegetative, resting) in their life cycle. I evaluate the morphological features of organic-walled unicellular microfossils in conjunction with their cell wall ultrastructure to infer their life cycle and to recognize various developmental stages represented among microfossils attributed to a single form-taxon. Several cases of fine wall ultrastructure in microfossils have been documented and have had a conclusive influence on understanding their affinities. Some Proterozoic and Cambrian leiosphaerids are of algal affinities. Certain specimens represent chlorophyceaens, having the multilayered composite wall with TLS structure known from vegetative and resting cells in modern genera of the Chlorococcales and Volvocales. The wall ultrastructure of

  14. Structural order in additive processed bulk heterojunction organic solar cells

    Science.gov (United States)

    Rogers, James Thomas

    Considerable academic and industrial efforts have been dedicated to resolving scientific and technological issues associated with the fabrication of efficient plastic solar cells via solution deposition techniques. The most successful strategy used to generate solution processable devices implements a two component donor-acceptor type system composed of a (p-type) narrow bandgap conjugated polymer donor blended with a (n-type) fullerene acceptor. Due to the limited exciton diffusion lengths (~10 nm) inherent to these materials, efficient photoinduced charge generation requires heterojunction formation (i.e. donor/acceptor interfaces) in close proximity to the region of exciton generation. Maximal charge extraction therefore requires that donor and acceptor components form nanoscale phase separated percolating pathways to their respective electrodes. Devices exhibiting these structural characteristics are termed bulk heterojunction devices (BHJ). Although the BHJ architecture highlights the basic characteristics of functional donor-acceptor type organic solar cells, device optimization requires internal order within each phase and proper organization relative to the substrate in order to maximize charge transport efficiencies and minimize charge carrier recombination losses. The economic viability of BHJ solar cells hinges upon the minimization of processing costs; thus, commercially relevant processing techniques should generate optimal structural characteristics during film formation, eliminating the need for additional post deposition processing steps. Empirical optimization has shown that solution deposition using high boiling point additives (e.g. octanedithiol (ODT)) provides a simple and widely used fabrication method for maximizing the power conversion efficiencies of BHJ solar cells. This work will show using x-ray scattering that a small percentage of ODT (~2%) in chlorobenzene induces the nucleation of polymeric crystallites within 2 min of deposition

  15. Penium margaritaceum as a model organism for cell wall analysis of expanding plant cells

    DEFF Research Database (Denmark)

    Rydahl, Maja Gro; Fangel, Jonatan Ulrik; Mikkelsen, Maria Dalgaard;

    2015-01-01

    organization of the polymeric networks of the cell wall around the protoplast also contributes to the direction of growth, the shape of the cell, and the proper positioning of the cell in a tissue. In essence, plant cell expansion represents the foundation of development. Most studies of plant cell expansion...

  16. Cytoskeleton reorganization and ultrastructural damage induced by gliadin in a three-dimensional in vitro model

    Institute of Scientific and Technical Information of China (English)

    Ersilia Dolfini; Leda Roncoroni; Luca Elli; Chiara Fumagalli; Roberto Colombo; Simona Ramponi; Fabio Forlani; Maria Teresa Bardella

    2005-01-01

    AIM: To evaluate the interplay between gliadin and LoVo cells and the direct effect of gliadin on cytoskeletal patterns.METHODS: We treated LoVo multicellular spheroids with digested bread wheat gliadin in order to investigate their morphology and ultrastructure (by means of light microscopy and scanning electron microscopy), and the effect of gliadin on actin (phalloidin fluorescence)and the tight-junction protein occludin and zonula occluden-1.RESULTS: The treated spheroids had deep holes and surface blebs, whereas the controls were smoothly surfaced ovoids. The incubation of LoVo spheroids with gliadin decreased the number of intracellular actin filaments, impaired and disassembled the integrity of the tight-junction system.CONCLUSION: Our data obtained from an "in vivolike" polarized culture system confirm the direct noxious effect of gliadin on the cytoskeleton and tight junctions of epithelial cells. Unlike two-dimensional cell culture systems, the use of multicellular spheroids seems to provide a suitable model for studying cell-cell interactions.

  17. Are maternal mitochondria the selfish entities that are masters of the cells of eukaryotic multicellular organisms?

    OpenAIRE

    Agnati, Luigi F.; Barlow, Peter W; Baldelli, E.; Baluška, Frantisek

    2009-01-01

    The Energide concept, as well as the endosymbiotic theory of eukaryotic cell organization and evolution, proposes that present-day cells of eukaryotic organisms are mosaics of specialized and cooperating units, or organelles. Some of these units were originally free-living prokaryotes, which were engulfed during evolutionary time. Mitochondria represent one of these types of previously independent organisms, the Energide, is another type. This new perspective on the organization of the cell h...

  18. Cell and Tissue Engineering

    CERN Document Server

    2012-01-01

    Cell and Tissue Engineering” introduces the principles and new approaches in cell and tissue engineering. It includes both the fundamentals and the current trends in cell and tissue engineering, in a way useful both to a novice and an expert in the field. The book is composed of 13 chapters all of which are written by the leading experts. It is organized to gradually assemble an insight in cell and tissue function starting form a molecular nano-level, extending to a cellular micro-level and finishing at the tissue macro-level. In specific, biological, physiological, biophysical, biochemical, medical, and engineering aspects are covered from the standpoint of the development of functional substitutes of biological tissues for potential clinical use. Topics in the area of cell engineering include cell membrane biophysics, structure and function of the cytoskeleton, cell-extracellular matrix interactions, and mechanotransduction. In the area of tissue engineering the focus is on the in vitro cultivation of ...

  19. Nanostructured thin films for organic photovoltaic cells and organic light-emitting diodes

    Science.gov (United States)

    Zheng, Ying

    2009-12-01

    Achieving efficient organic optoelectronic devices, such as organic photovoltaic (OPV) cells and organic light-emitting diodes (OLEDs), relies on the understanding of the formation of various organic nanostructures as well as the fundamental of physical processes in device operation. The research presented in this thesis systematically investigates the controlled growth of organic nanostructure through different approaches and their relationship to OPV cell performance. Moreover, new materials and device structure are explored to achieve efficient OLEDs, which also provide further insight of the physical processes governing the performance of these devices. We first investigated the phase separation process in a molecular mixed donor-acceptor (D -- A) bulk heterojunction (BHJ) composed of pentacene and C60 suing a combination of experimental and computational approaches. Both experiment characterization and the MD simulation reveals that strong aggregation of pentacene exists in the pentacene:C60 mixtures due to the strong pi -- pi interaction among pentacene molecules. By controlling the processing conditions to suppress the pentacene aggregation to nanoscale leads to higher device efficiency as the more photogenerated excitons are able to reach the D -- A interface and contribute to the photocurrent. To circumvent the limits on phase separated D -- A mixed heterojunction, an interdigitated D -- A BHJ is synthesized through the oblique angle deposition (OAD) of copper phthalocyanine (CuPc). The morphology of CuPc nanorod arrays grown under the OAD process can be controlled by careful selection of the processing conditions, and we have achieved a high density, vertically aligned, polycrystalline CuPc nanorod array with nanorod size as small as 20-30 nm. Successful infiltration of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) into the optimized CuPc nanorod arrays has resulted in doubling of the power conversion efficiency of the OPV cell over planar

  20. Heavy ion and X-ray irradiation alter the cytoskeleton and cytomechanics of cortical neurons

    Institute of Scientific and Technical Information of China (English)

    Yuting Du; Jie Zhang; Qian Zheng; Mingxin Li; Yang Liu; Baoping Zhang; Bin Liu; Hong Zhang; Guoying Miao

    2014-01-01

    Heavy ion beams with high linear energy transfer exhibit more beneifcial physical and biological performance than conventional X-rays, thus improving the potential of this type of radiotherapy in the treatment of cancer. However, these two radiotherapy modalities both cause inevitable brain injury. The objective of this study was to evaluate the effects of heavy ion and X-ray irra-diation on the cytoskeleton and cytomechanical properties of rat cortical neurons, as well as to determine the potential mechanism of neuronal injury after irradiation. Cortical neurons from 30 new-born mice were irradiated with heavy ion beams at a single dose of 2 Gy and X-rays at a single dose of 4 Gy;subsequent evaluation of their effects were carried out at 24 hours after irradiation. An immunolfuorescence assay showed that after irradiation with both the heavy ion beam and X-rays, the number of primary neurons was signiifcantly decreased, and there was ev-idence of apoptosis. Radiation-induced neuronal injury was more apparent after X-irradiation. Under atomic force microscopy, the neuronal membrane appeared rough and neuronal rigidity had increased. These cell changes were more apparent following exposure to X-rays. Our ifnd-ings indicated that damage caused by heavy ion and X-ray irradiation resulted in the structural distortion and rearrangement of the cytoskeleton, and affected the cytomechanical properties of the cortical neurons. Moreover, this radiation injury to normal neurons was much severer after irradiation with X-rays than after heavy ion beam irradiation.

  1. Emerging roles of actin cytoskeleton regulating enzymes in drug addiction: Actin or reactin’?

    Science.gov (United States)

    Rothenfluh, Adrian; Cowan, Christopher W.

    2013-01-01

    Neurons rely on their cytoskeleton to give them shape and stability, and on cytoskeletal dynamics for growth and synaptic plasticity. Because drug addiction is increasingly seen as the inappropriate learning of strongly reinforcing stimuli, the role of the cytoskeleton in shaping drug memories has been of increasing interest in recent years. Does the cytoskeleton have an active role in shaping these memories, and to what extent do alterations in the cytoskeleton reflect the acute actions of drug exposure, or homeostatic reactions to the chronic exposure to drugs of abuse? Here we will review recent advances in understanding the role of the cytoskeleton in the development of drug addiction, with a focus on actin filaments, as they have been studied in greater detail. PMID:23428655

  2. Influence of the fibroblastic reticular network on cell-cell interactions in lymphoid organs.

    Directory of Open Access Journals (Sweden)

    Frederik Graw

    Full Text Available Secondary lymphoid organs (SLO, such as lymph nodes and the spleen, display a complex micro-architecture. In the T cell zone the micro-architecture is provided by a network of fibroblastic reticular cells (FRC and their filaments. The FRC network is thought to enhance the interaction between immune cells and their cognate antigen. However, the effect of the FRC network on cell interaction cannot be quantified to date because of limitations in immunological methodology. We use computational models to study the influence of different densities of FRC networks on the probability that two cells meet. We developed a 3D cellular automaton model to simulate cell movements and interactions along the FRC network inside lymphatic tissue. We show that the FRC network density has only a small effect on the probability of a cell to come into contact with a static or motile target. However, damage caused by a disruption of the FRC network is greatest at FRC densities corresponding to densities observed in the spleen of naïve mice. Our analysis suggests that the FRC network as a guiding structure for moving T cells has only a minor effect on the probability to find a corresponding dendritic cell. We propose alternative hypotheses by which the FRC network might influence the functionality of immune responses in a more significant way.

  3. Studies on organic solar cells based on small-molecules : tetraphenyldibenzoperiflanthene and fullerene C70

    OpenAIRE

    Galindo Lorente, Sergi

    2015-01-01

    This work deals with the research on organic solar cells based on small-molecules semiconductors. In particular, organic solar cells of this thesis have been used tetraphenyldibenzoperiflanthene as donor material and fullerene C70 as acceptor material. In the first part of this thesis, we focus on the influence of the density of states of the donor layer on the characteristic parameters of solar cells. Further, organic solar cells with p-i-n structure are presented, where the intrinsic lay...

  4. Current progress and future perspectives for organic/inorganic perovskite solar cells

    OpenAIRE

    Boix, Pablo P.; Kazuteru Nonomura; Nripan Mathews; Subodh G. Mhaisalkar

    2014-01-01

    The recent emergence of efficient solar cells based on organic/inorganic lead halide perovskite absorbers promises to transform the fields of dye-sensitized, organic, and thin film solar cells. Solution processed photovoltaics incorporating perovskite absorbers have achieved efficiencies of 15% [1] in solid-state device configurations, superseding liquid dye sensitized solar cell (DSC), evaporated and tandem organic solar cells, as well as various thin film photovoltaics; thus establishing pe...

  5. Colchicine-induced polyploidization depends on tubulin polymerization in c-metaphase cells.

    Science.gov (United States)

    Caperta, A D; Delgado, M; Ressurreição, F; Meister, A; Jones, R N; Viegas, W; Houben, A

    2006-05-01

    The microtubule cytoskeleton plays a crucial role in the cell cycle and in mitosis. Colchicine is a microtubule-depolymerizing agent that has long been used to induce chromosome individualization in cells arrested at metaphase and also in the induction of polyploid plants. Although attempts have been made to explain the processes and mechanisms underlying polyploidy induction, the role of the cytoskeleton still remains largely unknown. Through immunodetection of alpha-tubulin, different concentrations (0.5 or 5 mM) of colchicine were found to produce opposite effects in the organization of the cytoskeleton in rye (Secale cereale L.). A low concentration (0.5 mM) induced depolymerization of the microtubular cytoskeleton in all phases of the cell cycle. In contrast, a high concentration (5 mM) was found to induce the polymerization of new tubulin-containing structures in c-metaphase cells. Furthermore, both treatments also showed contrasting effects in the induction of polyploid cells. Flow cytometric analysis and quantitative assessments of nucleolus-organizing regions revealed that only the high-concentration colchicine treatment was effective in the formation of polyploid cells. Our studies indicate that spindle disruption alone is insufficient for the induction of polyploid cells. The absence of any tubulin structures in plants treated with colchicine at the low concentration induced cell anomalies, such as the occurrence of nuclei with irregular shape and/or (additional) micronuclei, 12 h after recovery, pointing to a direct effect on cell viability. In contrast, the almost insignificant level of cell anomalies in the high-concentration treatment suggests that the presence of new tubulin-containing structures allows the reconstitution of 4C nuclei and their progression into the cell cycle. PMID:16520877

  6. Organic-inorganic hybrid nanostructures for solar cell applications

    Science.gov (United States)

    AbdulAlmohsin, Samir M.

    The enticing electro-optical properties of nanostructured materials such as carbon nanotubes, graphene, CdS nanocrystals and ZnO nanowrie bring new vigor into the innovation of photovoltaics. The main purpose of this dissertation is to develop novel nano-structured materials for low cost solar cell applications. Fabrication, characterization, and solar cell application of organic-inorganic hybrid structures are the main focus of this research. Polyaniline (PANI)/multi-walled carbon nanotube (MWNT) composite films were synthesized by an electrochemical polymerization of aniline with airbrushed MWNTs on ITO substrates. It was found that the incorporation of MWNTs in PANI effectively increase the film conductivity with a percolation threshold of 5% of nanotubes in the composite. The solar cell performance strongly depends on the conductivity of the composite films, which can be tuned by adjusting nanotube concentration. A higher conductivity resulted in a better cell performance, resulting from an efficient charge collection. This study indicates that PANI/MWNT composite films with optimized conductivity are potentially useful for low-cost hybrid solar cell applications. CdS nanocrystal-sensitized solar cells (NCSSCs) were investigated by using polyaniline (PANI) as a replacement for conventional platinum counter electrode. The growth time of the nanocrystals significantly affects the solar cell performance. At an optimum growth, the NCSSCs exhibit 0.83% of the conversion efficiency in comparison to 0.13% for the identical cells without CdS nanocrystals. Electrochemical impedance spectroscopy showed that the charge transfer in the solar cells with CdS nanocrystals was improved. The enhanced overall energy conversion efficiency by nanocrystals is attributed to improved light absorption and suppressed recombination rate of interfacial charges at the injection, resulting in significantly improved charge transfer and electron lifetime. In addition, the PANI electrodes

  7. Production, characterization and stability of organic solar cell devices

    Energy Technology Data Exchange (ETDEWEB)

    Gevorgyan, S.A.

    2010-01-15

    Despite the fact that the field of organic photovoltaics (OPVs) is in a rapid progress, organic solar cells continue taking backstage roll in the growing markets of various solar technologies. The main challenge of the field is to develop devices that would possess all the optimal properties required for efficient, stable and cheap solar cells, i.e. devices that can deliver high photoconversion efficiencies and long lifetimes and can be efficiently produced in large scales using roll-to-roll coating technologies. This dissertation is primarily devoted to the issues of photoconversion efficiency and device lifetimes. In particular, descriptions of some practical approaches for different device designs and processing of active layer for typical small scale OPV devices were presented. The emphasis was put on some optimizing techniques for processing of active layer that can significantly improve the device photoconversion efficiency. The techniques were further applied for manufacturing and characterization of solar cell devices based on various materials. In particular, a number of thermocleavable polymers were studied and devices based on such materials were produced and characterized. The applicability of such materials in photovoltaic devices was shown and further challenges were discussed. Another task of this work was to manufacture and study inverted device structures and compare their properties with normal structure based devices. Device based on both structure were successfully produced with same level of performance in terms of photoconversion efficiency, yet with totally different stability performance. As another task, metal oxides, such as MoO{sub 3} or V{sub 2}O{sub 5} were studied in solar cell devices as buffer layers instead of PEDOT:PSS. Although the device efficiencies obtained with metal oxides were inferior to PEDOT based device, it was shown that such materials can possibly improve the device efficiency if the processing of the layers is

  8. The Interference of Selected Cytotoxic Alkaloids with the Cytoskeleton: An Insight into Their Modes of Action.

    Science.gov (United States)

    Wang, Xiaojuan; Tanaka, Mine; Krstin, Sonja; Peixoto, Herbenya Silva; Wink, Michael

    2016-01-01

    Alkaloids, the largest group among the nitrogen-containing secondary metabolites of plants, usually interact with several molecular targets. In this study, we provide evidence that six cytotoxic alkaloids (sanguinarine, chelerythrine, chelidonine, noscapine, protopine, homoharringtonine), which are known to affect neuroreceptors, protein biosynthesis and nucleic acids, also interact with the cellular cytoskeleton, such as microtubules and actin filaments, as well. Sanguinarine, chelerythrine and chelidonine depolymerized the microtubule network in living cancer cells (Hela cells and human osteosarcoma U2OS cells) and inhibited tubulin polymerization in vitro with IC50 values of 48.41 ± 3.73, 206.39 ± 4.20 and 34.51 ± 9.47 μM, respectively. However, sanguinarine and chelerythrine did not arrest the cell cycle while 2.5 μM chelidonine arrested the cell cycle in the G₂/M phase with 88.27% ± 0.99% of the cells in this phase. Noscapine and protopine apparently affected microtubule structures in living cells without affecting tubulin polymerization in vitro, which led to cell cycle arrest in the G2/M phase, promoting this cell population to 73.42% ± 8.31% and 54.35% ± 11.26% at a concentration of 80 μM and 250.9 μM, respectively. Homoharringtonine did not show any effects on microtubules and cell cycle, while the known microtubule-stabilizing agent paclitaxel was found to inhibit tubulin polymerization in the presence of MAPs in vitro with an IC50 value of 38.19 ± 3.33 μM. Concerning actin filaments, sanguinarine, chelerythrine and chelidonine exhibited a certain effect on the cellular actin filament network by reducing the mass of actin filaments. The interactions of these cytotoxic alkaloids with microtubules and actin filaments present new insights into their molecular modes of action. PMID:27420038

  9. Stability of organic solar cells: challenges and strategies.

    Science.gov (United States)

    Cheng, Pei; Zhan, Xiaowei

    2016-05-01

    Organic solar cells (OSCs) present some advantages, such as simple preparation, light weight, low cost and large-area flexible fabrication, and have attracted much attention in recent years. Although the power conversion efficiencies have exceeded 10%, the inferior device stability still remains a great challenge. In this review, we summarize the factors limiting the stability of OSCs, such as metastable morphology, diffusion of electrodes and buffer layers, oxygen and water, irradiation, heating and mechanical stress, and survey recent progress in strategies to increase the stability of OSCs, such as material design, device engineering of active layers, employing inverted geometry, optimizing buffer layers, using stable electrodes and encapsulation. Some research areas of device stability that may deserve further attention are also discussed to help readers understand the challenges and opportunities in achieving high efficiency and high stability of OSCs towards future industrial manufacture. PMID:26890341

  10. Multiscale Modeling and Simulation of Organic Solar Cells

    CERN Document Server

    de Falco, Carlo; Sacco, Riccardo; Verri, Maurizio

    2012-01-01

    In this article, we continue our mathematical study of organic solar cells (OSCs) and propose a two-scale (micro- and macro-scale) model of heterojunction OSCs with interface geometries characterized by an arbitrarily complex morphology. The microscale model consists of a system of partial and ordinary differential equations in an heterogeneous domain, that provides a full description of excitation/transport phenomena occurring in the bulk regions and dissociation/recombination processes occurring in a thin material slab across the interface. The macroscale model is obtained by a micro-to-macro scale transition that consists of averaging the mass balance equations in the normal direction across the interface thickness, giving rise to nonlinear transmission conditions that are parametrized by the interfacial width. These conditions account in a lumped manner for the volumetric dissociation/recombination phenomena occurring in the thin slab and depend locally on the electric field magnitude and orientation. Usi...

  11. Optical enhancement effects of plasmonic nanostructures on organic photovoltaic cells

    KAUST Repository

    Park, Hui Joon

    2015-04-01

    © 2015 Hui Joon Park and L. Jay Guo. Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. All rights reserved. In this article, the optical enhancement effects of plasmonic nanostructures on OPV cells were reviewed as an effective way to resolve the mismatch problems between the short exciton diffusion length in organic semiconductors (around 10 nm) and the large thickness required to fully absorb sunlight (e.g. hundreds of nanometers). Especially, the performances of OPVs with plasmonic nanoparticles in photoactive and buffer layers and with periodic nanostructures were investigated. Furthermore, nanoimprint lithography-based nanofabrication processes that can easily control the dimension and uniformity of structures for large-area and uniform plasmonic nanostructures were demonstrated.

  12. Metal organic frameworks for enzyme immobilization in biofuel cells

    Science.gov (United States)

    Bodell, JaDee

    Interest in biofuel cells has been rapidly expanding as an ever-growing segment of the population gains access to electronic devices. The largest areas of growth for new populations using electronic devices are often in communities without electrical infrastructure. This lack of infrastructure in remote environments is one of the key driving factors behind the development of biofuel cells. Biofuel cells employ biological catalysts such as enzymes to catalyze oxidation and reduction reactions of select fuels to generate power. There are several benefits to using enzymes to catalyze reactions as compared to traditional fuel cells which use metal catalysts. First, enzymes are able to catalyze reactions at or near room temperature, whereas traditional metal catalysts are only efficient at very high temperatures. Second, biofuel cells can operate under mild pH conditions which is important for the eventual design of safe, commercially viable devices. Also, biofuel cells allow for implantable and flexible technologies. Finally, enzymes exhibit high selectivity and can be combined to fully oxidize or reduce the fuel which can generate several electrons from a single molecule of fuel, increasing the overall device efficiency. One of the main challenges which persist in biofuel cells is the instability of enzymes over time which tend to denature after hours or days. For a viable commercial biofuel cell to be produced, the stability of enzymes must be extended to months or years. Enzymes have been shown to have improved stability after being immobilized. The focus of this research was to find a metal organic framework (MOF) structure which could successfully immobilize enzymes while still allowing for electron transport to occur between the catalytic center of the enzyme and the electrode surface within a biofuel cell for power generation. Four MOF structures were successfully synthesized and were subsequently tested to determine the MOF's ability to immobilize the following

  13. Power losses in bilayer inverted small molecule organic solar cells

    KAUST Repository

    Trinh, Cong

    2012-01-01

    Inverted bilayer organic solar cells using copper phthalocyanine (CuPc) as a donor and C60 as an acceptor with the structure: glass/indium tin oxide (ITO)/ZnO/C60/CuPc/MoO3/Al, in which the zinc oxide (ZnO) was deposited by atomic layer deposition, are compared with a conventional device: glass/ITO/CuPc/C60/bathocuproine/Al. These inverted and conventional devices give short circuit currents of 3.7 and 4.8 mA/cm 2, respectively. However, the inverted device gives a reduced photoresponse from the CuPc donor compared to that of the conventional device. Optical field models show that the arrangement of organic layers in the inverted devices leads to lower absorption of long wavelengths by the CuPc donor; the low energy portion of the spectrum is concentrated near the metal oxide electrode in both devices. © 2012 American Institute of Physics.

  14. Effects of polar cortical cytoskeleton and unbalanced cortical surface tension on intercellular bridge thinning during cytokinesis

    Institute of Scientific and Technical Information of China (English)

    Li Wang; Mei-Wen An; Xiao-Na Li; Fang Yang; Yang Liu

    2011-01-01

    To probe the contributions of polar cortical cytoskeleton and the surface tension of daughter cells to intercellular bridgethinning dynamics during cytokinesis,we applied cytochalasin D (CD) or colchicine (COLC) in a highly localized manner to polar regions of dividing normal rat kidney (NRK) cells.We observed cellular morphological changes and analyzed the intercellular bridge thinning trajectories of dividing cells with different polar cortical characteristics.Global blebbistatin (BS) application was used to obtain cells losing active contractile force groups.Our results show that locally released CD or colchicine at the polar region caused inhibition of cytokinesis before ingression.Similar treatment at phases after ingression allowed completion of cytokinesis but dramatically influenced the trajectories of intercellular bridge thinning.Disturbing single polar cortical actin induced transformation of the intercellular bridge thinning process,and polar cortical tension controlled deformation time of intercellular bridges.Our study provides a feasible framework to induce and analyze the effects of local changes in mechanical properties of cellular components on single cellular cytokinesis.

  15. From cells to organisms: Can we learn about aging from cells in culture?

    International Nuclear Information System (INIS)

    Can studying cultured cells inform us about the biology of aging? The idea that this may be was stimulated by the first formal description of replicative senescence. Replicative senescence limits the proliferation of normal human cells in culture, causing them to irreversibly arrest growth and adopt striking changes in cell function. We now know that telomere shortening, which occurs in most somatic cells as a consequence of DNA replication, drives replicative senescence in human cells. However, rodent cells also undergo replicative senescence, despite very long telomeres, and DNA damage,the action of certain oncogenes and changes in chromatin induce a phenotype similar to that of replicatively senescent cells. Thus,replicative senescence is an example of the more general process of cellular senescence, indicating that the telomere hypothesis of aging is a misnomer. Cellular senescence appears to be a response to potentially oncogenic insults, including oxidative stress. The growth arrest almost certainly suppresses tumorigenesis, at least in young organisms, whereas the functional changes may contribute to aging,although this has yet to be critically tested. Thus, cellular senescence may be an example of antagonistic pleiotropy.Cross-species comparisons suggest there is a relationship between the senescence of cells in culture and organismal life span, but the relationship is neither quantitative nor direct

  16. Tmod1 and CP49 synergize to control the fiber cell geometry, transparency, and mechanical stiffness of the mouse lens.

    Directory of Open Access Journals (Sweden)

    David S Gokhin

    Full Text Available The basis for mammalian lens fiber cell organization, transparency, and biomechanical properties has contributions from two specialized cytoskeletal systems: the spectrin-actin membrane skeleton and beaded filament cytoskeleton. The spectrin-actin membrane skeleton predominantly consists of α₂β₂-spectrin strands interconnecting short, tropomyosin-coated actin filaments, which are stabilized by pointed-end capping by tropomodulin 1 (Tmod1 and structurally disrupted in the absence of Tmod1. The beaded filament cytoskeleton consists of the intermediate filament proteins CP49 and filensin, which require CP49 for assembly and contribute to lens transparency and biomechanics. To assess the simultaneous physiological contributions of these cytoskeletal networks and uncover potential functional synergy between them, we subjected lenses from mice lacking Tmod1, CP49, or both to a battery of structural and physiological assays to analyze fiber cell disorder, light scattering, and compressive biomechanical properties. Findings show that deletion of Tmod1 and/or CP49 increases lens fiber cell disorder and light scattering while impairing compressive load-bearing, with the double mutant exhibiting a distinct phenotype compared to either single mutant. Moreover, Tmod1 is in a protein complex with CP49 and filensin, indicating that the spectrin-actin network and beaded filament cytoskeleton are biochemically linked. These experiments reveal that the spectrin-actin membrane skeleton and beaded filament cytoskeleton establish a novel functional synergy critical for regulating lens fiber cell geometry, transparency, and mechanical stiffness.

  17. Self-Organizing Maps on the Cell Broadband Engine Architecture

    International Nuclear Information System (INIS)

    We present and evaluate novel parallel implementations of Self-Organizing Maps for the Cell Broadband Engine Architecture. Motivated by the interactive nature of the data-mining process, we evaluate the scalability of the implementations on two clusters using different network characteristics and incarnations (PS3TMconsole and PowerXCell 8i) of the architecture. Our implementations use varying combinations of the Power Processing Elements (PPEs) and Synergistic Processing Elements (SPEs) found in the Cell architecture. For a single processor, our implementation scaled well with the number of SPEs regardless of the incarnation. When combining multiple PS3TMconsoles, the synchronization over the slower network resulted in poor speedups and demonstrated that the use of such a low-cost cluster may be severely restricted, even without the use of SPEs. When using multiple SPEs for the PowerXCell 8i cluster, the speedup grew linearly with increasing number of SPEs for a given number of processors, and linear up to a maximum with the number of processors for a given number of SPEs. Our implementation achieved a worst-case efficiency of 67% for the maximum number of processing elements involved in the computation, but consistently higher values for smaller numbers of processing elements with speedups of up to 70.

  18. Film stresses and electrode buckling in organic solar cells

    KAUST Repository

    Brand, Vitali

    2012-08-01

    We investigate the film stresses that develop in the polymer films and metal electrodes of poly(3-hexyl thiophene) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM) bulk heterojunction (BHJ) organic solar cells. A compressive biaxial stress of ∼-36 MPa was measured in PEDOT:PSS while a tensile stress of ∼6 MPa was measured in the BHJ layer. We then analyze the effect of electrode deposition rate on the film stresses in the Al electrode. Compressive stresses of ∼-100 to -145 MPa in the Al electrode lead to a buckling instability resulting in undulating electrode surface topography. The BHJ layer was found to have the lowest cohesion (∼1.5-1.8 J/m 2) among the layers of the solar cell and dependent on the Al electrode deposition rate. The cohesive failure path in the BHJ layer exhibited the same periodicity and orientation of the Al electrode buckling topography. We discuss the implications of the film stresses on damage processes during device fabrication and operation. © 2012 Elsevier B.V. All rights reserved.

  19. Degradation of Flexible, ITO-Free Oligothiophene Organic Solar Cells.

    Science.gov (United States)

    Bormann, Ludwig; Nehm, Frederik; Sonntag, Luisa; Chen, Fan-Yu; Selzer, Franz; Müller-Meskamp, Lars; Eychmüller, Alexander; Leo, Karl

    2016-06-15

    We investigate the degradation of organic solar cells based on an oligothiophene (DCV5T-Me) small molecule donor and the acceptor C60. Two different flexible, transparent bottom electrode types are employed: a transparent metal electrode (TME) and silver nanowires (AgNWs). They exhibit high optical transparency up to 86% and a sheet resistance as low as 12Ω/□. Power conversion efficiencies of 7.0%, 5.7%, and 7.2% on TME, AgNWs, and indium tin oxide (ITO, reference) are reached, respectively. The solar cells are protected against moisture ingress utilizing a flexible alumina thin-film, exhibiting water vapor transmission rates down to 3 × 10(-5) g m(-2) day(-1) at 38 °C and 90% relative humidity (RH). Implementation of this ultrabarrier as top and bottom encapsulation enables fabrication of fully flexible devices. A decrease in PCE to 80% of initial values is observed after 1000 ± 50 h on flexible, encapsulated TME but only 20 ± 5 h on AgNWs in a climate of 38 °C/50% RH. Degradation in AgNW-based devices is attributed to electrode decomposition. PMID:27218608

  20. Development of Polymer Acceptors for Organic Photovoltaic Cells

    Directory of Open Access Journals (Sweden)

    Yujeong Kim

    2014-02-01

    Full Text Available This review provides a current status report of the various n-type polymer acceptors for use as active materials in organic photovoltaic cells (OPVs. The polymer acceptors are divided into four categories. The first section of this review focuses on rylene diimide-based polymers, including perylene diimide, naphthalene diimide, and dithienocoronene diimide-based polymers. The high electron mobility and good stability of rylene diimides make them suitable for use as polymer acceptors in OPVs. The second section deals with fluorene and benzothiadiazole-based polymers such as poly(9,9’-dioctylfluorene-co-benzothiadiazole, and the ensuing section focuses on the cyano-substituted polymer acceptors. Cyano-poly(phenylenevinylene and poly(3-cyano-4-hexylthiophene have been used as acceptors in OPVs and exhibit high electron affinity arising from the electron-withdrawing cyano groups in the vinylene group of poly(phenylenevinylene or the thiophene ring of polythiophene. Lastly, a number of other electron-deficient groups such as thiazole, diketopyrrolopyrrole, and oxadiazole have also been introduced onto polymer backbones to induce n-type characteristics in the polymer. Since the first report on all-polymer solar cells in 1995, the best power conversion efficiency obtained with these devices to date has been 3.45%. The overall trend in the development of n-type polymer acceptors is presented in this review.

  1. Solution-Processable Organic Molecule for High-Performance Organic Solar Cells with Low Acceptor Content.

    Science.gov (United States)

    Wang, Kun; Guo, Bing; Xu, Zhuo; Guo, Xia; Zhang, Maojie; Li, Yongfang

    2015-11-11

    A new planar D2-A-D1-A-D2 structured organic molecule with bithienyl benzodithiophene (BDT) as central donor unit D1 and fluorine-substituted benzothiadiazole (BTF) as acceptor unit and alkyl-dithiophene as end group and donor unit D2, BDT-BTF, was designed and synthesized for the application as donor material in organic solar cells (OSCs). BDT-BTF shows a broad absorption in visible region, suitable highest occupied molecular orbital energy level of -5.20 eV, and high hole mobility of 1.07 × 10(-2) cm(2)/(V s), benefitted from its high coplanarity and strong crystallinity. The OSCs based on BDT-BTF as donor (D) and PC71BM as acceptor (A) at a D/A weight ratio of 3:1 without any extra treatment exhibit high photovoltaic performance with Voc of 0.85 V, Jsc of 10.48 mA/cm(2), FF of 0.66, and PCE of 5.88%. The morphological study by transmission electron microscopy reveals that the blend of BDT-BTF and PC71BM (3:1, w/w) possesses an appropriate interpenetrating D/A network for the exciton separation and charge carrier transport, which agrees well with the good device performance. The optimized D/A weight ratio of 3:1 is the lowest acceptor content in the active layer reported so far for the high-performance OSCs, and the organic molecules with the molecular structure like BDT-BTF could be promising high-performance donor materials in solution-processable OSCs. PMID:26492421

  2. Association of thrombospondin-1 with the actin cytoskeleton of human thrombin-activated platelets through an alphaIIbbeta3- or CD36-independent mechanism.

    Science.gov (United States)

    Saumet, Anne; Jesus, Nando de; Legrand, Chantal; Dubernard, Véronique

    2002-01-01

    Thrombospondin-1 (TSP-1) is an adhesive glycoprotein which, when secreted from alpha-granules of activated platelets, can bind to the cell surface and participate in platelet aggregate formation. In this study, we show that thrombin activation leads to the rapid and specific association of a large amount of secreted alpha-granular TSP-1 with the actin cytoskeleton. This cytoskeletal association of TSP-1 was correlated with platelet secretion, but not aggregation, and was inhibited by cytochalasin D, an inhibitor of actin polymerization. Association of TSP-1 with the actin cytoskeleton was mediated by membrane receptors, as shown by using MAII, a TSP-1-specific monoclonal antibody that inhibited both TSP-1 surface binding to activated platelets and cytoskeletal association. TSP-1 and its potential membrane receptors, e.g. alphaIIbbeta3 integrin, CD36 and CD47, concomitantly associated with the actin cytoskeleton. However, studies on platelets from a patient with type I Glanzmann's thrombasthenia lacking alphaIIbbeta3 and another with barely detectable CD36 showed normal TSP-1 surface expression and association with the actin cytoskeleton. Likewise, no involvement of CD47 in TSP-1 association with the actin cytoskeleton could be inferred from experiments with control platelets using the function-blocking anti-CD47 antibody B6H12. Finally, assembly of signalling complexes, as observed through translocation of tyrosine-phosphorylated proteins and kinases to the actin cytoskeleton, was found to occur in concert with cytoskeletal association of TSP-1, in control platelets as well as in thrombasthenic and CD36-deficient platelets. Our results imply a role for the actin cytoskeleton in the membrane-surface expression process of TSP-1 molecules and suggest a possible coupling of TSP-1 receptors to signalling events occurring independently of alphaIIbbeta3 or CD36. These results provide new insights into the link between surface-bound TSP-1 and the contractile actin

  3. Jak3 enables chemokine-dependent actin cytoskeleton reorganization by regulating cofilin and Rac/Rhoa GTPases activation.

    Directory of Open Access Journals (Sweden)

    Xochitl Ambriz-Peña

    Full Text Available We have previously shown that Jak3 is involved in the signaling pathways of CCR7, CCR9 and CXCR4 in murine T lymphocytes and that Jak3⁻/⁻ lymphocytes display an intrinsic defect in homing to peripheral lymph nodes. However, the molecular mechanism underlying the defective migration observed in Jak3⁻/⁻ lymphocytes remains elusive. Here, it is demonstrated for the first time, that Jak3 is required for the actin cytoskeleton reorganization in T lymphocytes responding to chemokines. It was found that Jak3 regulates actin polymerization by controlling cofilin inactivation in response to CCL21 and CXCL12. Interestingly, cofilin inactivation was not precluded in PTX- treated cells despite their impaired actin polymerization. Additionally, Jak3 was required for small GTPases Rac1 and RhoA activation, which are indispensable for acquisition of the migratory cell phenotype and the generation of a functional leading edge and uropod, respectively. This defect correlates with data obtained by time-lapse video-microscopy showing an incompetent uropod formation and impaired motility in Jak3-pharmacologically inhibited T lymphocytes. Our data support a new model in which Jak3 and heterotrimeric G proteins can use independent, but complementary, signaling pathways to regulate actin cytoskeleton dynamics during cell migration in response to chemokines.

  4. Ligand-induced association of surface immunoglobulin with the detergent insoluble cytoskeleton may involve an 89K protein

    International Nuclear Information System (INIS)

    Membrane immunoglobulin of B-lymphocytes is thought to play an important role in antigen recognition and cellular activation. Binding of cross-linking ligands to surface immunoglobulin (SIg) on intact cells converts it to a detergent insoluble state, and this conversion is associated with the transmission of a mitogenic signal. Insolubilized membrane proteins may be solubilized by incubating the detergent insoluble cytoskeletons in buffers which convert F-actin to G-actin [(Buffer 1), 0.34M sucrose, 0.5mM ATP, 0.5mM Dithiothrietol and lmM EDTA]. Immunoprecipitation of SIg from the detergent soluble fraction of 35S-methionine labeled non ligand treated rat B-cells results in the co-isolation of an 89K protein and a 44K protein, presumably actin. The 89K protein is not associated with the fraction of endogenous detergent insoluble SIg. On treatment of rat B cells with cross-linking ligand (anti-Ig) the 89K protein becomes detergent insoluble along with most of the SIg and co-isolates with SIg on immunoprecipitation of the detergent insoluble, buffer l solubilized fraction. The migration of the SIg-associated 89K protein from the detergent soluble fraction to the detergent insoluble fraction after ligand treatment, suggests that this protein might be involved in linking SIg to the underlying cytoskeleton and could be involved in the transmission of a mitogenic signal

  5. The plant cytoskeleton: recent advances in the study of the plant microtubule-associated proteins MAP-65, MAP-190 and the Xenopus MAP215-like protein, MOR1.

    Science.gov (United States)

    Hussey, Patrick J; Hawkins, Timothy J; Igarashi, Hisako; Kaloriti, Despina; Smertenko, Andrei

    2002-12-01

    The microtubule cytoskeleton is a dynamic filamentous structure involved in many key processes in plant cell morphogenesis including nuclear and cell division, deposition of cell wall, cell expansion, organelle movement and secretion. The principal microtubule protein is tubulin, which associates to form the wall of the tubule. In addition, various associated proteins bind microtubules either to anchor, cross-link or regulate the microtubule network within cells. Biochemical, molecular biological and genetic approaches are being successfully used to identify these microtubule-associated proteins (MAPs) in plants, and we describe recent progress on three of these proteins. PMID:12516862

  6. The cell nucleus taking centre stage. Workshop on the functional organization of the cell nucleus

    Czech Academy of Sciences Publication Activity Database

    Gruenbaum, Y.; Raška, Ivan; Herrmann, H.

    2006-01-01

    Roč. 7, č. 12 (2006), s. 1211-1215. ISSN 1469-221X. [EMBO Workshop on the Functional Organization of the Cell Nucleus /3./. Prague, 05.05.2006-08.05.2006] R&D Projects: GA ČR(CZ) GA304/04/0692; GA ČR(CZ) GA304/06/1691; GA MŠk(CZ) LC535 Institutional research plan: CEZ:AV0Z50110509 Keywords : cell nucleus * nuclear dynamics * nuclear structure and disease Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 8.175, year: 2006

  7. Tropomyosin - master regulator of actin filament function in the cytoskeleton.

    Science.gov (United States)

    Gunning, Peter W; Hardeman, Edna C; Lappalainen, Pekka; Mulvihill, Daniel P

    2015-08-15

    Tropomyosin (Tpm) isoforms are the master regulators of the functions of individual actin filaments in fungi and metazoans. Tpms are coiled-coil parallel dimers that form a head-to-tail polymer along the length of actin filaments. Yeast only has two Tpm isoforms, whereas mammals have over 40. Each cytoskeletal actin filament contains a homopolymer of Tpm homodimers, resulting in a filament of uniform Tpm composition along its length. Evidence for this 'master regulator' role is based on four core sets of observation. First, spatially and functionally distinct actin filaments contain different Tpm isoforms, and recent data suggest that members of the formin family of actin filament nucleators can specify which Tpm isoform is added to the growing actin filament. Second, Tpms regulate whole-organism physiology in terms of morphogenesis, cell proliferation, vesicle trafficking, biomechanics, glucose metabolism and organ size in an isoform-specific manner. Third, Tpms achieve these functional outputs by regulating the interaction of actin filaments with myosin motors and actin-binding proteins in an isoform-specific manner. Last, the assembly of complex structures, such as stress fibers and podosomes involves the collaboration of multiple types of actin filament specified by their Tpm composition. This allows the cell to specify actin filament function in time and space by simply specifying their Tpm isoform composition. PMID:26240174

  8. ARG1 (altered response to gravity) encodes a DnaJ-like protein that potentially interacts with the cytoskeleton

    Science.gov (United States)

    Sedbrook, J. C.; Chen, R.; Masson, P. H.

    1999-01-01

    Gravitropism allows plant organs to direct their growth at a specific angle from the gravity vector, promoting upward growth for shoots and downward growth for roots. Little is known about the mechanisms underlying gravitropic signal transduction. We found that mutations in the ARG1 locus of Arabidopsis thaliana alter root and hypocotyl gravitropism without affecting phototropism, root growth responses to phytohormones or inhibitors of auxin transport, or starch accumulation. The positional cloning of ARG1 revealed a DnaJ-like protein containing a coiled-coil region homologous to coiled coils found in cytoskeleton-interacting proteins. These data suggest that ARG1 participates in a gravity-signaling process involving the cytoskeleton. A combination of Northern blot studies and analysis of ARG1-GUS fusion-reporter expression in transgenic plants demonstrated that ARG1 is expressed in all organs. Ubiquitous ARG1 expression in Arabidopsis and the identification of an ortholog in Caenorhabditis elegans suggest that ARG1 is involved in other essential processes.

  9. Partitioning of Nanoparticles into Organic Phases and Model Cells

    Energy Technology Data Exchange (ETDEWEB)

    Posner, J.D.; Westerhoff, P.; Hou, W-C.

    2011-08-25

    There is a recognized need to understand and predict the fate, transport and bioavailability of engineered nanoparticles (ENPs) in aquatic and soil ecosystems. Recent research focuses on either collection of empirical data (e.g., removal of a specific NP through water or soil matrices under variable experimental conditions) or precise NP characterization (e.g. size, degree of aggregation, morphology, zeta potential, purity, surface chemistry, and stability). However, it is almost impossible to transition from these precise measurements to models suitable to assess the NP behavior in the environment with complex and heterogeneous matrices. For decades, the USEPA has developed and applies basic partitioning parameters (e.g., octanol-water partition coefficients) and models (e.g., EPI Suite, ECOSAR) to predict the environmental fate, bioavailability, and toxicity of organic pollutants (e.g., pesticides, hydrocarbons, etc.). In this project we have investigated the hypothesis that NP partition coefficients between water and organic phases (octanol or lipid bilayer) is highly dependent on their physiochemical properties, aggregation, and presence of natural constituents in aquatic environments (salts, natural organic matter), which may impact their partitioning into biological matrices (bioaccumulation) and human exposure (bioavailability) as well as the eventual usage in modeling the fate and bioavailability of ENPs. In this report, we use the terminology "partitioning" to operationally define the fraction of ENPs distributed among different phases. The mechanisms leading to this partitioning probably involve both chemical force interactions (hydrophobic association, hydrogen bonding, ligand exchange, etc.) and physical forces that bring the ENPs in close contact with the phase interfaces (diffusion, electrostatic interactions, mixing turbulence, etc.). Our work focuses on partitioning, but also provides insight into the relative behavior of ENPs as either "more like

  10. Effect of simultaneous electrical and thermal treatment on the performance of bulk heterojunction organic solar cell blended with organic salt

    Energy Technology Data Exchange (ETDEWEB)

    Sabri, Nasehah Syamin; Yap, Chi Chin; Yahaya, Muhammad [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Salleh, Muhamad Mat [Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia)

    2013-11-27

    This work presents the influence of simultaneous electrical and thermal treatment on the performance of organic solar cell blended with organic salt. The organic solar cells were composed of indium tin oxide as anode, poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene]: (6,6)-phenyl-C61 butyric acid methyl ester: tetrabutylammonium hexafluorophosphate blend as organic active layer and aluminium as cathode. The devices underwent a simultaneous fixed-voltage electrical and thermal treatment at different temperatures of 25, 50 and 75 °C. It was found that photovoltaic performance improved with the thermal treatment temperature. Accumulation of more organic salt ions in the active layer leads to broadening of p-n doped regions and hence higher built-in electric field across thin intrinsic layer. The simultaneous electrical and thermal treatment has been shown to be able to reduce the electrical treatment voltage.

  11. On the ultrastructure of Trichomonas vaginalis: cytoskeleton, endocytosis and hydrogenosomes

    Directory of Open Access Journals (Sweden)

    SIXTO RAUL COSTAMAGNA

    2001-07-01

    Full Text Available This paper is focused on the study of the ultrastructure of Trichomonas vaginalis in liquid cultures. Its cytoskeleton, the morphology of its hydrogenosomes, and endocytosis phenomena have been observed by scanning electron microscopy (SEM and transmission electron microscopy (TEM. For the present study, the traditional techniques for SEM and TEM have been slightly modified for the processing of this flagellate. Following our experiments, it can be concluded that: 1. The modified techniques are adequate for the ultrastructural study of this protozoon. 2. There are no mitochondria in T. vaginalis. 3. T. vaginalis might use micropinocytosis processes related to coated vesicles as a habitual endo- and exocytosis mechanism, while phagocytosis is observed for major vesicles. 4. As to the cytoskeleton, microtubules are numerous and display different structures, which are analyzed in this paper. 5. Many hydrogenosomes are found in the cytoplasm of T. vaginalis underneath the undulating membrane and along the axostyle, each with electron-dense deposits in the manner of «operculums.»El presente estudio está referido a la ultraestructura de Trichomonas vaginalis, cultivadas en medio líquido. Su citoesqueleto, fenómenos de endocitosis y la morfología de sus hidrogenosomas fueron observados por microscopía electrónica de barrido y de transmisión. Las técnicas clásicas para el procesamiento al SEM y TEM de este flagelado, fueron discreta y sutilmente modificadas por nosotros. Como resultado de nuestras experiencias se concluye que: 1. Las técnicas modificadas empleadas son adecuadas para el estudio morfológico y ultraestructural de este Protozoo. 2. Al TEM su citoplasma no muestra mitocondrias. 3. Utiliza los fenómenos de micropinocitosis asociados con vesículas con cubierta como mecanismo habitual de endo y exocitosis selectiva, mientras que para partículas mayores la fagocitosis es frecuentemente vista. 4. Con referencia al citoesqueleto

  12. Vibrational spectroscopy of photosensitizer dyes for organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Perez Leon, C.

    2005-11-18

    Ruthenium(II) complexes containing polypyridyl ligands are intensely investigated as potential photosensitizers in organic solar cells. Of particular interest is their use in dye-sensitized solar cells based on nanocrystalline films of TiO{sub 2}. Functional groups of the dye allow for efficient anchoring on the semiconductor surface and promote the electronic communication between the donor orbital of the dye and the conduction band of the semiconductor. In the present work a new dye, [Ru(dcbpyH{sub 2}){sub 2}(bpy-TPA{sub 2})](PF6{sub )2}, and the well known (Bu{sub 4}N){sub 2}[Ru(dcbpyH){sub 2}(NCS){sub 2}] complex were spectroscopically characterized. The electronic transitions of both dyes showed solvatochromic shifts due to specific interactions of the ligands with the solvent molecules. The surface-enhanced Raman (SER) spectra of the dyes dissolved in water, ethanol, and acetonitrile were measured in silver and gold colloidal solutions. The results demonstrate that the dyes were adsorbed on the metallic nanoparticles in different ways for different solvents. It was also found that in the gold colloid, the aqueous solutions of both dyes did not produce any SERS signal, whereas in ethanolic solution the SERS effect was very weak. Deprotonation, H-bonding, and donor-acceptor interactions seem to determine these different behaviors. Our results indicate the important role of the charge transfer mechanism in SERS. The adsorption of the dye on two different TiO{sub 2} substrates, anatase paste films and anatase nanopowder, was also studied to clarify the role of the carboxylate groups in the anchoring process of the dyes on the semiconductor surface. The recorded spectra indicate a strong dependence of the anchoring configuration on the morphology of the semiconductor. (orig.)

  13. A critical test of organic P-N photovoltaic cells

    Energy Technology Data Exchange (ETDEWEB)

    Bird, G.R. [Rutgers Univ., Piscataway, NJ (United States)

    1996-09-01

    We present an urgent view of the field of organic solid state photovoltaic cells. This is a proper time to select the most promising materials from the Electrophotographic Industry, materials long tried in terms of stability, high quantum yield of charge carriers, but set apart by unusually high quantum yields at low applied fields. Our experience with the candidate dyes has covered new tests for identifiable impurities and removal of these impurities by verifiable methods. A new method of purification, reactive train sublimation, has been developed for DNT, one of the simplest of the outstanding perylene dyes, and the method seems applicable to some of the other promising perylene derivatives. It removes the offending impurity by converting it into the desired pure product. The role of water of hydration in the {open_quotes}wine cellar effect{close_quotes}, the slowly rising performance of newly made phthalocyanine containing cells has been analyzed. Under the concept of feasibility testing before a final refinement for practicality of materials and production methods, the hydration can be controlled for high level testing. At the same time, efforts go forward to eliminate the need. At least one of the best phthalocyanine components, X-H{sub 2}Pc, does not require water for peak performance. Finally, we have attacked BBIP (bis-benzimidazole perylene) one of the best and most enigmatic of the near infrared sensors. It has long been known and used as a mixture of synthetic isomers, and we hypothesize that either of these would be better than the uncontrolled mixture. A partial success in the form of isolating highly enriched crystals for an X-ray structure of the trans-molecule, is first presented here. A simple optical analysis method has been developed to follow enrichment procedures. For all of its difficult history, this material seems closest to a state of readiness for critical feasibility testing.

  14. Clathrin-dependent pathways and the cytoskeleton network are involved in ceramide endocytosis by a parasitic protozoan, Giardia lamblia.

    Science.gov (United States)

    Hernandez, Yunuen; Castillo, Cynthia; Roychowdhury, Sukla; Hehl, Adrian; Aley, Stephen B; Das, Siddhartha

    2007-01-01

    Although identified as an early-diverged protozoan, Giardia lamblia shares many similarities with higher eukaryotic cells, including an internal membrane system and cytoskeleton, as well as secretory pathways. However, unlike many other eukaryotes, Giardia does not synthesize lipids de novo, but rather depends on exogenous sources for both energy production and organelle or membrane biogenesis. It is not known how lipid molecules are taken up by this parasite and if endocytic pathways are involved in this process. In this investigation, we tested the hypothesis that highly regulated and selective lipid transport machinery is present in Giardia and necessary for the efficient internalization and intracellular targeting of ceramide molecules, the major sphingolipid precursor. Using metabolic and pathway inhibitors, we demonstrate that ceramide is internalized through endocytic pathways and is primarily targeted into perinuclear/endoplasmic reticulum membranes. Further investigations suggested that Giardia uses both clathrin-dependent pathways and the actin cytoskeleton for ceramide uptake, as well as microtubule filaments for intracellular localization and targeting. We speculate that this parasitic protozoan has evolved cytoskeletal and clathrin-dependent endocytic mechanisms for importing ceramide molecules from the cell exterior for the synthesis of membranes and vesicles during growth and differentiation. PMID:17087963

  15. Cytoskeletal dependence of insulin granule movement dynamics in INS-1 beta-cells in response to glucose.

    Directory of Open Access Journals (Sweden)

    Aoife T Heaslip

    Full Text Available For pancreatic β-cells to secrete insulin in response to elevated blood glucose, insulin granules retained within the subplasmalemmal space must be transported to sites of secretion on the plasma membrane. Using a combination of super-resolution STORM imaging and live cell TIRF microscopy we investigate how the organization and dynamics of the actin and microtubule cytoskeletons in INS-1 β-cells contribute to this process. GFP-labeled insulin granules display 3 different modes of motion (stationary, diffusive-like, and directed. Diffusive-like motion dominates in basal, low glucose conditions. Upon glucose stimulation no gross rearrangement of the actin cytoskeleton is observed but there are increases in the 1 rate of microtubule polymerization; 2 rate of diffusive-like motion; and 3 proportion of granules undergoing microtubule-based directed motion. By pharmacologically perturbing the actin and microtubule cytoskeletons, we determine that microtubule-dependent granule transport occurs within the subplasmalemmal space and that the actin cytoskeleton limits this transport in basal conditions, when insulin secretion needs to be inhibited.

  16. Charge extraction from nanostructured hybrid organic-inorganic photovoltaic cells

    Science.gov (United States)

    Goh, Chiatzun

    suppresses charge recombination across the TiO 2/P3HT interface. By controlling open circuit voltage, enhancing photocurrent and suppressing recombination through interface modification, the power efficiency of TiO2/P3HT device is almost doubled. Lastly, we demonstrate a novel imprinting method to nanostructure straight pores in TiO2, which can be infiltrated with conjugated polymers to make ordered inorganic-organic PV cells.

  17. Fabrication of Organic Bulk Heterojunction Solar Cells on Flexible Substrates

    Science.gov (United States)

    Calderon, Gabriel; Merced-Sanabria, Milzaida; Carradero-Santiago, Carolyn; Vedrine-Pauléus, Josee

    2015-03-01

    The active layer for the organic solar cells fabricated is composed of P3HT:PCBM, poly(3-hexylthiophene) (P3HT) as electron donor and phenyl-C61-butyric acid methyl ester(PCBM) as electron acceptor. These polymers were used due to their promising characteristics for devices such as bulk heterojunction solar devices. We used polyethylene terephthalate (PET) substrates, a highly flexible plastic, with indium tin oxide (ITO) as the transparent conducting anode for the device, and UV lithography technique to pattern the ITO; this is to facilitate multiple devices on a single substrate. The fabrication process for pattern transfer incorporates developing and etching processes. We diluted the HCl and DI water to etch out the ITO. PEDOT:PSS and active layer of P3HT:PCBM were deposited on (3.0 sq-cm) patterned of ITO/PET by spin coating method. The cathode was thermally evaporated with Al. We characterized the device using a sourcemeter. We also simulated portions of the device using PET on graphene as the substrate.

  18. Selective Interlayers and Contacts in Organic Photovoltaic Cells.

    Science.gov (United States)

    Ratcliff, Erin L; Zacher, Brian; Armstrong, Neal R

    2011-06-01

    Organic photovoltaic cells (OPVs) are promising solar electric energy conversion systems with impressive recent optimization of active layers. OPV optimization must now be accompanied by the development of new charge-selective contacts and interlayers. This Perspective considers the role of interface science in energy harvesting using OPVs, looking back at early photoelectrochemical (photogalvanic) energy conversion platforms, which suffered from a lack of charge carrier selectivity. We then examine recent platforms and the fundamental aspects of selective harvesting of holes and electrons at opposite contacts. For blended heterojunction OPVs, contact/interlayer design is especially critical because charge harvesting competes with recombination at these same contacts. New interlayer materials can modify contacts to both control work function and introduce selectivity and chemical compatibility with nonpolar active layers and add thermodynamic and kinetic selectivity to charge harvesting. We briefly discuss the surface and interface science required for the development of new interlayer materials and take a look ahead at the challenges yet to be faced in their optimization. PMID:26295432

  19. Interfacial thermal degradation in inverted organic solar cells

    International Nuclear Information System (INIS)

    The efficiency of organic photovoltaic (OPV) solar cells is constantly improving; however, the lifetime of the devices still requires significant improvement if the potential of OPV is to be realised. In this study, several series of inverted OPV were fabricated and thermally aged in the dark in an inert atmosphere. It was demonstrated that all of the devices undergo short circuit current-driven degradation, which is assigned to morphology changes in the active layer. In addition, a previously unreported, open circuit voltage-driven degradation mechanism was observed that is highly material specific and interfacial in origin. This mechanism was specifically observed in devices containing MoO3 and silver as hole transporting layers and electrode materials, respectively. Devices with this combination were among the worst performing devices with respect to thermal ageing. The physical origins of this mechanism were explored by Rutherford backscattering spectrometry and atomic force microscopy and an increase in roughness with thermal ageing was observed that may be partially responsible for the ageing mechanism

  20. Organic solar cells using CVD-grown graphene electrodes

    International Nuclear Information System (INIS)

    We report on the development of flexible organic solar cells (OSCs) incorporating graphene sheets synthesized by chemical vapor deposition (CVD) as transparent conducting electrodes on polyethylene terephthalate (PET) substrates. A key barrier that must be overcome for the successful fabrication of OSCs with graphene electrodes is the poor-film properties of water-based poly(3,4-ethylenedioxythiphene):poly(styrenesulfonate) (PEDOT:PSS) when coated onto hydrophobic graphene surfaces. To form a uniform PEDOT:PSS film on a graphene surface, we added perfluorinated ionomers (PFI) to pristine PEDOT:PSS to create ‘GraHEL’, which we then successfully spin coated onto the graphene surface. We systematically investigated the effect of number of layers in layer-by-layer stacked graphene anode of an OSC on the performance parameters including the open-circuit voltage (Voc), short-circuit current (Jsc), and fill factor (FF). As the number of graphene layers increased, the FF tended to increase owing to lower sheet resistance, while Jsc tended to decrease owing to the lower light absorption. In light of this trade-off between sheet resistance and transmittance, we determined that three-layer graphene (3LG) represents the best configuration for obtaining the optimal power conversion efficiency (PCE) in OSC anodes, even at suboptimal sheet resistances. We finally developed efficient, flexible OSCs with a PCE of 4.33%, which is the highest efficiency attained so far by an OSC with CVD-grown graphene electrodes to the best of our knowledge. (paper)

  1. Interfacial thermal degradation in inverted organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Greenbank, William; Hirsch, Lionel; Wantz, Guillaume; Chambon, Sylvain, E-mail: sylvain.chambon@ims-bordeaux.fr [University of Bordeaux, CNRS, Bordeaux INP, IMS, UMR 5218, F-33405 Talence (France)

    2015-12-28

    The efficiency of organic photovoltaic (OPV) solar cells is constantly improving; however, the lifetime of the devices still requires significant improvement if the potential of OPV is to be realised. In this study, several series of inverted OPV were fabricated and thermally aged in the dark in an inert atmosphere. It was demonstrated that all of the devices undergo short circuit current-driven degradation, which is assigned to morphology changes in the active layer. In addition, a previously unreported, open circuit voltage-driven degradation mechanism was observed that is highly material specific and interfacial in origin. This mechanism was specifically observed in devices containing MoO{sub 3} and silver as hole transporting layers and electrode materials, respectively. Devices with this combination were among the worst performing devices with respect to thermal ageing. The physical origins of this mechanism were explored by Rutherford backscattering spectrometry and atomic force microscopy and an increase in roughness with thermal ageing was observed that may be partially responsible for the ageing mechanism.

  2. TFB:TPDSi2 interfacial layer usable in organic photovoltaic cells

    Energy Technology Data Exchange (ETDEWEB)

    Marks, Iobin J. (Evanston, IL); Hains, Alexander W. (Evanston, IL)

    2011-02-15

    The present invention, in one aspect, relates to a solar cell. In one embodiment, the solar cell includes an anode; an active organic layer comprising an electron-donating organic material and an electron-accepting organic material; and an interfacial layer formed between the anode and active organic layer, where the interfacial layer comprises a hole-transporting polymer characterized with a hole-mobility higher than that of the electron-donating organic material in the active organic layer, and a small molecule that has a high hole-mobility and is capable of crosslinking on contact with air.

  3. Cytoskeleton in Pollen and Pollen Tubes of Ginkgo biloba L.

    Institute of Scientific and Technical Information of China (English)

    Jun-Mei LIU; Hong ZHANG; Yan LI

    2005-01-01

    The distribution of F-actin and microtubules was investigated in pollen and pollen tubes of Ginkgo biloba L. using a confocal laser scanning microscope after fluorescence and immunofluorescence labeling. A dense F-actin network was found in hydrated Ginkgo pollen. When Ginkgo pollen was germinating,F-actin mesh was found under the plasma membrane from which the pollen tube would emerge. After pollen germination, F-actin bundles were distributed axially in long pollen tubes of G. biloba. Thick F-actin bundles and network were found in the tip of the Ginkgo pollen tube, which is opposite to the results reported for the pollen tubes of some angiosperms and conifers. In addition, a few circular F-actin bundles were found in Ginkgo pollen tubes. Using immunofluorescence labeling, a dense microtubule network was found in hydrated Ginkgo pollen under confocal microscope. In the Ginkgo pollen tube, the microtubules were distributed along the longitudinal axis and extended to the tip. These results suggest that the cytoskeleton may have an essential role in the germination of Ginkgo pollen and tube growth.

  4. Towards High Performance Organic Photovoltaic Cells: A Review of Recent Development in Organic Photovoltaics

    Directory of Open Access Journals (Sweden)

    Junsheng Yu

    2014-09-01

    Full Text Available Organic photovoltaic cells (OPVs have been a hot topic for research during the last decade due to their promising application in relieving energy pressure and environmental problems caused by the increasing combustion of fossil fuels. Much effort has been made toward understanding the photovoltaic mechanism, including evolving chemical structural motifs and designing device structures, leading to a remarkable enhancement of the power conversion efficiency of OPVs from 3% to over 15%. In this brief review, the advanced progress and the state-of-the-art performance of OPVs in very recent years are summarized. Based on several of the latest developed approaches to accurately detect the separation of electron-hole pairs in the femtosecond regime, the theoretical interpretation to exploit the comprehensive mechanistic picture of energy harvesting and charge carrier generation are discussed, especially for OPVs with bulk and multiple heterojunctions. Subsequently, the novel structural designs of the device architecture of OPVs embracing external geometry modification and intrinsic structure decoration are presented. Additionally, some approaches to further increase the efficiency of OPVs are described, including thermotics and dynamics modification methods. Finally, this review highlights the challenges and prospects with the aim of providing a better understanding towards highly efficient OPVs.

  5. Mesenchymal Stem Cell Therapy for Protection and Repair of Injured Vital Organs

    NARCIS (Netherlands)

    van Poll, D.; Parekkadan, B.; Rinkes, I. H. M. Borel; Tilles, A. W.; Yarmush, M. L.

    2008-01-01

    Recently there has been a paradigm shift in what is considered to be the therapeutic promise of mesenchymal stem cells (MSCs) in diseases of vital organs. Originally, research focused on MSCs as a source of regenerative cells by differentiation of transplanted cells into lost cell types. It is now c

  6. Cell and Tissue Organization in the Circulatory and Ventilatory Systems Volume 1 Signaling in Cell Organization, Fate, and Activity, Part A Cell Structure and Environment

    CERN Document Server

    Thiriet, Marc

    2011-01-01

    The volumes in this authoritative series present a multidisciplinary approach to modeling and simulation of flows in the cardiovascular and ventilatory systems, especially multiscale modeling and coupled simulations. The cardiovascular and respiratory systems are tightly coupled, as their primary function is to supply oxygen to and remove carbon dioxide from the body's cells. Because physiological conduits have deformable and reactive walls, macroscopic flow behavior and prediction must be coupled to nano- and microscopic events in a corrector scheme of regulated mechanisms. Therefore, investigation of flows of blood and air in physiological conduits requires an understanding of the biology, chemistry, and physics of these systems together with the mathematical tools to describe their functioning.  The present volume is devoted to cellular events that allow adaptation to environmental conditions, particularly mechanotransduction. It begins with cell organization and a survey of cell types in the vasculatur...

  7. PreImplantation factor (PIF*) regulates systemic immunity and targets protective regulatory and cytoskeleton proteins.

    Science.gov (United States)

    Barnea, Eytan R; Hayrabedyan, Soren; Todorova, Krassimira; Almogi-Hazan, Osnat; Or, Reuven; Guingab, Joy; McElhinney, James; Fernandez, Nelson; Barder, Timothy

    2016-07-01

    Secreted by viable embryos, PIF is expressed by the placenta and found in maternal circulation. It promotes implantation and trophoblast invasion, achieving systemic immune homeostasis. Synthetic PIF successfully transposes endogenous PIF features to non-pregnant immune and transplant models. PIF affects innate and activated PBMC cytokines and genes expression. We report that PIF targets similar proteins in CD14+, CD4+ and CD8+ cells instigating integrated immune regulation. PIF-affinity chromatography followed by mass-spectrometry, pathway and heatmap analysis reveals that SET-apoptosis inhibitor, vimentin, myosin-9 and calmodulin are pivotal for immune regulation. PIF acts on macrophages down-stream of LPS (lipopolysaccharide-bacterial antigen) CD14/TLR4/MD2 complex, targeting myosin-9, thymosin-α1 and 14-3-3eta. PIF mainly targets platelet aggregation in CD4+, and skeletal proteins in CD8+ cells. Pathway analysis demonstrates that PIF targets and regulates SET, tubulin, actin-b, and S100 genes expression. PIF targets systemic immunity and has a short circulating half-life. Collectively, PIF targets identified; protective, immune regulatory and cytoskeleton proteins reveal mechanisms involved in the observed efficacy against immune disorders. PMID:26944449

  8. Shigella flexneri utilize the spectrin cytoskeleton during invasion and comet tail generation

    Directory of Open Access Journals (Sweden)

    Ruetz Tyson J

    2012-03-01

    Full Text Available Abstract Background The spectrin cytoskeleton is emerging as an important host cell target of enteric bacterial pathogens. Recent studies have identified a crucial role for spectrin and its associated proteins during key pathogenic processes of Listeria monocytogenes and Salmonella Typhimurium infections. Here we investigate the involvement of spectrin cytoskeletal components during the pathogenesis of the invasive pathogen Shigella flexneri. Results Immunofluorescent microscopy reveals that protein 4.1 (p4.1, but not adducin or spectrin, is robustly recruited to sites of S. flexneri membrane ruffling during epithelial cell invasion. Through siRNA-mediated knockdowns, we identify an important role for spectrin and the associated proteins adducin and p4.1 during S. flexneri invasion. Following internalization, all three proteins are recruited to the internalized bacteria, however upon generation of actin-rich comet tails, we observed spectrin recruitment to those structures in the absence of adducin or p4.1. Conclusion These findings highlight the importance of the spectrin cytoskeletal network during S. flexneri pathogenesis and further demonstrate that pathogenic events that were once thought to exclusively recruit the actin cytoskeletal system require additional cytoskeletal networks.

  9. Secretion mechanisms of volatile organic compounds in specialized cells of aromatic plants

    OpenAIRE

    Caissard, Jean-Claude; Joly, Caroline; Bergougnoux, Véronique; Hugueney, Philippe; Mauriat, Mélanie; Baudino, Sylvie

    2004-01-01

    The present review focuses on cells secreting volatile odorant compounds. This cell type is found in a wide variety of plants, grouped under the term aromatic plants. Such secreting cells are very diverse in morphology, from highly specialized trichomes to nonspecialized cells, including the secretory epidermal cells of petals and osmophores. In these various types of cell, the biosynthetic pathways of three main groups of volatile organic compounds are recognized: isoprenoids, fatty acid der...

  10. Endometrial mesenchymal stem cells as a cell based therapy for pelvic organ prolapse

    Science.gov (United States)

    Emmerson, Stuart J; Gargett, Caroline E

    2016-01-01

    Pelvic organ prolapse (POP) occurs when the pelvic organs (bladder, bowel or uterus) herniate into the vagina, causing incontinence, voiding, bowel and sexual dysfunction, negatively impacting upon a woman’s quality of life. POP affects 25% of all women and results from childbirth injury. For 19% of all women, surgical reconstructive surgery is required for treatment, often augmented with surgical mesh. The surgical treatment fails in up to 30% of cases or results in adverse effects, such as pain and mesh erosion into the bladder, bowel or vagina. Due to these complications the Food and Drug Administration cautioned against the use of vaginal mesh and several major brands have been recently been withdrawn from market. In this review we will discuss new cell-based approaches being developed for the treatment of POP. Several cell types have been investigated in animal models, including a new source of mesenchymal stem/stromal cells (MSC) derived from human endometrium. The unique characteristics of endometrial MSC, methods for their isolation and purification and steps towards their development for good manufacturing practice production will be described. Animal models that could be used to examine the potential for this approach will also be discussed as will a rodent model showing promise in developing an endometrial MSC-based therapy for POP. The development of a preclinical large animal model for assessing tissue engineering constructs for treating POP will also be mentioned. PMID:27247705

  11. Endometrial mesenchymal stem cells as a cell based therapy for pelvic organ prolapse.

    Science.gov (United States)

    Emmerson, Stuart J; Gargett, Caroline E

    2016-05-26

    Pelvic organ prolapse (POP) occurs when the pelvic organs (bladder, bowel or uterus) herniate into the vagina, causing incontinence, voiding, bowel and sexual dysfunction, negatively impacting upon a woman's quality of life. POP affects 25% of all women and results from childbirth injury. For 19% of all women, surgical reconstructive surgery is required for treatment, often augmented with surgical mesh. The surgical treatment fails in up to 30% of cases or results in adverse effects, such as pain and mesh erosion into the bladder, bowel or vagina. Due to these complications the Food and Drug Administration cautioned against the use of vaginal mesh and several major brands have been recently been withdrawn from market. In this review we will discuss new cell-based approaches being developed for the treatment of POP. Several cell types have been investigated in animal models, including a new source of mesenchymal stem/stromal cells (MSC) derived from human endometrium. The unique characteristics of endometrial MSC, methods for their isolation and purification and steps towards their development for good manufacturing practice production will be described. Animal models that could be used to examine the potential for this approach will also be discussed as will a rodent model showing promise in developing an endometrial MSC-based therapy for POP. The development of a preclinical large animal model for assessing tissue engineering constructs for treating POP will also be mentioned. PMID:27247705

  12. Graft-infiltrating host dendritic cells play a key role in organ transplant rejection.

    Science.gov (United States)

    Zhuang, Quan; Liu, Quan; Divito, Sherrie J; Zeng, Qiang; Yatim, Karim M; Hughes, Andrew D; Rojas-Canales, Darling M; Nakao, A; Shufesky, William J; Williams, Amanda L; Humar, Rishab; Hoffman, Rosemary A; Shlomchik, Warren D; Oberbarnscheidt, Martin H; Lakkis, Fadi G; Morelli, Adrian E

    2016-01-01

    Successful engraftment of organ transplants has traditionally relied on preventing the activation of recipient (host) T cells. Once T-cell activation has occurred, however, stalling the rejection process becomes increasingly difficult, leading to graft failure. Here we demonstrate that graft-infiltrating, recipient (host) dendritic cells (DCs) play a key role in driving the rejection of transplanted organs by activated (effector) T cells. We show that donor DCs that accompany heart or kidney grafts are rapidly replaced by recipient DCs. The DCs originate from non-classical monocytes and form stable, cognate interactions with effector T cells in the graft. Eliminating recipient DCs reduces the proliferation and survival of graft-infiltrating T cells and abrogates ongoing rejection or rejection mediated by transferred effector T cells. Therefore, host DCs that infiltrate transplanted organs sustain the alloimmune response after T-cell activation has already occurred. Targeting these cells provides a means for preventing or treating rejection. PMID:27554168

  13. Probing the role of the actin cytoskeleton during regulated exocytosis by intravital microscopy

    OpenAIRE

    Milberg, Oleg; Tora, Muhibullah; Shitara, Akiko; Masedunskas, Andrius; Weigert, Roberto

    2014-01-01

    The actin cytoskeleton plays a fundamental role in controlling several steps during regulated exocytosis. Here we describe a combination of procedures that are aimed at studying the dynamics and the mechanism of the actin cytoskeleton in the salivary glands of live rodents, a model for exocrine secretion. Our approach relies on intravital microscopy, an imaging technique that enables imaging biological events in live animals at a subcellular resolution, and it is complemented by the use of ph...

  14. Palmitic acid-labeled lipids selectively incorporated into platelet cytoskeleton during aggregation

    International Nuclear Information System (INIS)

    Previous experiments showed that during the early stages (20-30 seconds) of aggregation induced by adenosine diphosphate (ADP, 2 microM) or thrombin (0.1 U/mL) of rabbit or human platelets prelabeled with [3H]palmitic acid, labeled lipid became associated with the cytoskeleton isolated after lysis with 1% Triton X-100, 5 mM EGTA [ethylene glycol-bis-(beta-aminoethyl ether)]-N,N,N',N'-tetra-acetic acid. The association appeared to be related to the number of sites of contact and was independent of the release of granule contents. We have now investigated the nature of the labeled lipids by thin-layer and column chromatography and found differences between the distribution of the label in intact platelets (both stimulated and unstimulated) and the isolated cytoskeletons. In both species, and with either ADP or thrombin as aggregating agent, 70-85% of the label in both intact platelets and in the cytoskeletons was in phospholipids. The distribution of label among the phospholipids in the cytoskeletons was similar to that in intact platelets except that the percentage of label in phosphatidylcholine was significantly higher in the cytoskeletons of human platelets than in the intact platelets, and the percentage of label in phosphatidylserine/phosphatidylinositol was significantly lower in the cytoskeletons of rabbit platelets and thrombin-aggregated human platelets than in intact platelets. The cytoskeletons contained a lower percentage of label in triacylglycerol, diacylglycerol, and cholesterol ester than the intact platelets. Contrary to a report in the literature, we found no evidence for the incorporation of diacylglycerol and palmitic acid into the cytoskeleton

  15. Incineration of organic solar cells: Efficient end of life management by quantitative silver recovery

    DEFF Research Database (Denmark)

    Søndergaard, Roar R.; Zimmermann, Yannick Serge; Espinosa Martinez, Nieves; Lenz, Markus; Krebs, Frederik C

    2016-01-01

    Recovery of silver from the electrodes of roll-to-roll processed organic solar cells after incineration has been performed quantitatively by extraction with nitric acid. This procedure is more than 10 times faster than previous reports and the amount of acid needed for the extraction is reduced by...... justify the use of Ag as an electrode in scaled production of organic solar cells....

  16. From Learning Object to Learning Cell: A Resource Organization Model for Ubiquitous Learning

    Science.gov (United States)

    Yu, Shengquan; Yang, Xianmin; Cheng, Gang; Wang, Minjuan

    2015-01-01

    This paper presents a new model for organizing learning resources: Learning Cell. This model is open, evolving, cohesive, social, and context-aware. By introducing a time dimension into the organization of learning resources, Learning Cell supports the dynamic evolution of learning resources while they are being used. In addition, by introducing a…

  17. Distribution, Arrangement and Interconnectedness of Cell Surface Receptor sites in the body of an Organism

    Directory of Open Access Journals (Sweden)

    Utoh-Nedosa

    2011-01-01

    Full Text Available Cell surface receptors have been identified as the sites of disease infectivity in living organisms in a previous study. Drugs used for the treatment or cure of infections have to eliminate infections through attacking infective organisms at the cell surface receptors to which the infective organisms are attached. Problem statement: The present study examines a wide sample of living things to get more information on the relationship of one cell surface receptor to other cell surface receptors in the body of an organism. Approach: The arrangement of cell surface receptors on the external covering of a few samples of fruits, leaves, stems, dry wood of a plant; wall gecko and some parts of the human body, were examined and photographed. Transverse and/or Longitudinal sections of soursop fruit and sycamore fruit were also examined and photographed. The five different coverings of the fleshy part of a coconut were also photographed. The photographs were studied to note the relationship of disease infection attached to cell surface receptors on the external surface of an organ to disease infection on the innermost covering of the same organ. Results: The results of the study showed that all living things had ubiquitous distribution of cell surface receptors which are usually observable with the unaided eye as dots or spots on the external covering of an organ, tissue or cell. The dots or receptor sites of cell surface receptors in the study are arranged in lines which were perpendicular, oblique, transverse or arranged in any other lineal geometrical form. The lineally arranged cell surface receptors were noted to be connected by grooves, channels or pipes which joined other receptor channels or intersected with them. Smaller cell surface receptor channels emptied into bigger channels or continued as small sized channels that ran side by side in a connective tissue bundle. These connective tissue bundles that carried many independent small-sized cell

  18. Investigation of Annealing and Blend Concentration Effects of Organic Solar Cells Composed of Small Organic Dye and Fullerene Derivative

    Directory of Open Access Journals (Sweden)

    Yasser A. M. Ismail

    2011-01-01

    Full Text Available We have fabricated bulk heterojunction organic solar cells using coumarin 6 (C6 as a small organic dye, for light harvesting and electron donation, with fullerene derivative [6,6]-phenyl-C61 butyric acid methyl ester (PCBM, acting as an electron acceptor, by spin-coating technique. We have investigated thermal annealing and blend concentration effects on light harvesting, photocurrent, and performance parameters of the solar cells. In this work, we introduced an experimental method by which someone can easily detect the variation in the contact between active layer and cathode due to thermal annealing after cathode deposition. We have showed, in this work, unusual behavior of solar cell composed of small organic molecules under the influence of thermal annealing at different conditions. This behavior seemed uncommon for polymer solar cells. We try from this work to understand device physics and to locate a relationship between production parameters and performance parameters of the solar cell based on small organic molecules.

  19. The CPEB3 Protein Is a Functional Prion that Interacts with the Actin Cytoskeleton

    Directory of Open Access Journals (Sweden)

    Joseph S. Stephan

    2015-06-01

    Full Text Available The mouse cytoplasmic polyadenylation element-binding protein 3 (CPEB3 is a translational regulator implicated in long-term memory maintenance. Invertebrate orthologs of CPEB3 in Aplysia and Drosophila are functional prions that are physiologically active in the aggregated state. To determine if this principle applies to the mammalian CPEB3, we expressed it in yeast and found that it forms heritable aggregates that are the hallmark of known prions. In addition, we confirm in the mouse the importance of CPEB3’s prion formation for CPEB3 function. Interestingly, deletion analysis of the CPEB3 prion domain uncovered a tripartite organization: two aggregation-promoting domains surround a regulatory module that affects interaction with the actin cytoskeleton. In all, our data provide direct evidence that CPEB3 is a functional prion in the mammalian brain and underline the potential importance of an actin/CPEB3 feedback loop for the synaptic plasticity underlying the persistence of long-term memory.

  20. Transient phosphorylation of tumor associated microtubule associated protein (TMAP)/cytoskeleton associated protein 2 (CKAP2) at Thr-596 during early phases of mitosis

    OpenAIRE

    Hong, Kyung Uk; Choi, Yong-Bock; Lee, Jung-Hwa; Kim, Hyun-Jun; Kwon, Hye-Rim; Seong, Yeon-Sun; KIM, HEUNG TAE; Park, Joobae; Bae, Chang-Dae; Hong, Kyeong-Man

    2008-01-01

    Tumor associated microtubule associated protein (TMAP), also known as cytoskeleton associated protein 2 (CKAP2) is a mitotic spindle-associated protein whose expression is cell cycle-regulated and also frequently deregulated in cancer cells. Two monoclonal antibodies (mAbs) against TMAP/CKAP2 were produced: B-1-13 and D-12-3. Interestingly, the reactivity of mAb D-12-3 to TMAP/CKAP2 was markedly decreased specifically in mitotic cell lysate. The epitope mapping study showed that mAb D-12-3 re...