Distinguishing between stochasticity and determinism: Examples from cell cycle duration variability.

PubMed

Pearl Mizrahi, Sivan; Sandler, Oded; Lande-Diner, Laura; Balaban, Nathalie Q; Simon, Itamar

2016-01-01

We describe a recent approach for distinguishing between stochastic and deterministic sources of variability, focusing on the mammalian cell cycle. Variability between cells is often attributed to stochastic noise, although it may be generated by deterministic components. Interestingly, lineage information can be used to distinguish between variability and determinism. Analysis of correlations within a lineage of the mammalian cell cycle duration revealed its deterministic nature. Here, we discuss the sources of such variability and the possibility that the underlying deterministic process is due to the circadian clock. Finally, we discuss the "kicked cell cycle" model and its implication on the study of the cell cycle in healthy and cancerous tissues. © 2015 WILEY Periodicals, Inc.

Regulation of steroid hormone receptors and coregulators during the cell cycle highlights potential novel function in addition to roles as transcription factors

PubMed Central

Zheng, Yingfeng; Murphy, Leigh C.

2016-01-01

Cell cycle progression is tightly controlled by several kinase families including Cyclin-Dependent Kinases, Polo-Like Kinases, and Aurora Kinases. A large amount of data show that steroid hormone receptors and various components of the cell cycle, including cell cycle regulated kinases, interact, and this often results in altered transcriptional activity of the receptor. Furthermore, steroid hormones, through their receptors, can also regulate the transcriptional expression of genes that are required for cell cycle regulation. However, emerging data suggest that steroid hormone receptors may have roles in cell cycle progression independent of their transcriptional activity. The following is a review of how steroid receptors and their coregulators can regulate or be regulated by the cell cycle machinery, with a particular focus on roles independent of transcription in G2/M. PMID:26778927

Mammalian Homologs of Yeast Checkpoint Genes

DTIC Science & Technology

2002-07-01

pathway is sensitive to various forms of DNA damage Developmental Biology throughout the cell cycle . The DNA replication check- Yale University point...components would be ordered into pathways for mammalian checkpoint function, with emphasis on p53 regulation, cell cycle regulation, and complementation...structurally related to the human tumor suppressor ATM. MEC1 and RAD53, two essential genes, play a central role in DNA damage checkpoints at all cell cycle

Hydrogen-Oxygen PEM Regenerative Fuel Cell at NASA Glenn Research Center

NASA Technical Reports Server (NTRS)

Bents, David J.

2004-01-01

The NASA Glenn Research Center has constructed a closed-cycle hydrogen-oxygen PEM regenerative fuel cell (RFC) to explore its potential use as an energy storage device for a high altitude solar electric aircraft. Built up over the last 2 years from specialized hardware and off the shelf components the Glenn RFC is a complete "brassboard" energy storage system which includes all the equipment required to (1) absorb electrical power from an outside source and store it as pressurized hydrogen and oxygen and (2) make electrical power from the stored gases, saving the product water for re-use during the next cycle. It consists of a dedicated hydrogen-oxygen fuel cell stack and an electrolyzer stack, the interconnecting plumbing and valves, cooling pumps, water transfer pumps, gas recirculation pumps, phase separators, storage tanks for oxygen (O2) and hydrogen (H2), heat exchangers, isolation valves, pressure regulators, nitrogen purge provisions, instrumentation, and other components. It specific developmental functions include: (1) Test fuel cells and fuel cell components under repeated closed-cycle operation (nothing escapes; everything is used over and over again). (2) Simulate diurnal charge-discharge cycles (3) Observe long-term system performance and identify degradation and loss mechanisms. (4) Develop safe and convenient operation and control strategies leading to the successful development of mission-capable, flight-weight RFC's.

Intercellular Variability in Protein Levels from Stochastic Expression and Noisy Cell Cycle Processes

PubMed Central

Soltani, Mohammad; Vargas-Garcia, Cesar A.; Antunes, Duarte; Singh, Abhyudai

2016-01-01

Inside individual cells, expression of genes is inherently stochastic and manifests as cell-to-cell variability or noise in protein copy numbers. Since proteins half-lives can be comparable to the cell-cycle length, randomness in cell-division times generates additional intercellular variability in protein levels. Moreover, as many mRNA/protein species are expressed at low-copy numbers, errors incurred in partitioning of molecules between two daughter cells are significant. We derive analytical formulas for the total noise in protein levels when the cell-cycle duration follows a general class of probability distributions. Using a novel hybrid approach the total noise is decomposed into components arising from i) stochastic expression; ii) partitioning errors at the time of cell division and iii) random cell-division events. These formulas reveal that random cell-division times not only generate additional extrinsic noise, but also critically affect the mean protein copy numbers and intrinsic noise components. Counter intuitively, in some parameter regimes, noise in protein levels can decrease as cell-division times become more stochastic. Computations are extended to consider genome duplication, where transcription rate is increased at a random point in the cell cycle. We systematically investigate how the timing of genome duplication influences different protein noise components. Intriguingly, results show that noise contribution from stochastic expression is minimized at an optimal genome-duplication time. Our theoretical results motivate new experimental methods for decomposing protein noise levels from synchronized and asynchronized single-cell expression data. Characterizing the contributions of individual noise mechanisms will lead to precise estimates of gene expression parameters and techniques for altering stochasticity to change phenotype of individual cells. PMID:27536771

DNA replication checkpoint promotes G1-S transcription by inactivating the MBF repressor Nrm1

PubMed Central

de Bruin, R. A. M.; Kalashnikova, T. I.; Aslanian, A.; Wohlschlegel, J.; Chahwan, C.; Yates, J. R.; Russell, P.; Wittenberg, C.

2008-01-01

The cell cycle transcriptional program imposes order on events of the cell-cycle and is a target for signals that regulate cell-cycle progression, including checkpoints required to maintain genome integrity. Neither the mechanism nor functional significance of checkpoint regulation of the cell-cycle transcription program are established. We show that Nrm1, an MBF-specific transcriptional repressor acting at the transition from G1 to S phase of the cell cycle, is at the nexus between the cell cycle transcriptional program and the DNA replication checkpoint in fission yeast. Phosphorylation of Nrm1 by the Cds1 (Chk2) checkpoint protein kinase, which is activated in response to DNA replication stress, promotes its dissociation from the MBF transcription factor. This leads to the expression of genes encoding components that function in DNA replication and repair pathways important for cell survival in response to arrested DNA replication. PMID:18682565

Cell type-specific translational repression of Cyclin B during meiosis in males.

PubMed

Baker, Catherine Craig; Gim, Byung Soo; Fuller, Margaret T

2015-10-01

The unique cell cycle dynamics of meiosis are controlled by layers of regulation imposed on core mitotic cell cycle machinery components by the program of germ cell development. Although the mechanisms that regulate Cdk1/Cyclin B activity in meiosis in oocytes have been well studied, little is known about the trans-acting factors responsible for developmental control of these factors in male gametogenesis. During meiotic prophase in Drosophila males, transcript for the core cell cycle protein Cyclin B1 (CycB) is expressed in spermatocytes, but the protein does not accumulate in spermatocytes until just before the meiotic divisions. Here, we show that two interacting proteins, Rbp4 and Fest, expressed at the onset of spermatocyte differentiation under control of the developmental program of male gametogenesis, function to direct cell type- and stage-specific repression of translation of the core G2/M cell cycle component cycB during the specialized cell cycle of male meiosis. Binding of Fest to Rbp4 requires a 31-amino acid region within Rbp4. Rbp4 and Fest are required for translational repression of cycB in immature spermatocytes, with Rbp4 binding sequences in a cell type-specific shortened form of the cycB 3' UTR. Finally, we show that Fest is required for proper execution of meiosis I. © 2015. Published by The Company of Biologists Ltd.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shier, W.T.

Normally a freeze-thaw cycle is a very efficient method of killing mammalian cells. However, this report describes conditions that prevent killing of cultured mammalian cells by nucleated freezing at -24 degrees C. Optimal protection from cell killing at -24 degrees C was obtained in isotonic solutions containing an organic cryoprotectant such as dimethyl sulfoxide (DMSO; 10%, v/v), a saccharide such as sucrose over a broad concentration range from 50 to 150 mM, and glucose. Glycerol was also an effective cryoprotectant but other organic solvents were ineffective, although in some cases they appeared to protect cell membranes, while not protecting othermore » vital components. A wide variety of saccharide structures were effective at protecting cells from freeze-thaw killing, with trehalose being particularly effective. The degree of resistance to killing by a freeze-thaw cycle under these conditions varied widely among different cell lines. If toxicity of DMSO was responsible for this variability of cryoprotection, it must have been due to short-term, not longer term, toxicity of DMSO. Studies on the mechanism by which cells are protected from killing under these conditions indicated that neither vitrification of the medium nor the concentrating of components during freezing were involved. One model not eliminated by the mechanistic studies proposes that the organic solvent cryoprotectant component acts by fluidizing membranes under the thawing conditions, so that any holes produced by ice crystals propagating through membranes can reseal during the thawing process. In this model one of the mechanisms by which the saccharide component could act is by entering the cells and stabilizing vital intracellular components. Consistent with this, a freeze-thaw cycle promoted the uptake of labeled sucrose into cultured cells.« less

The Nuclear and Adherent Junction Complex Component Protein Ubinuclein Negatively Regulates the Productive Cycle of Epstein-Barr Virus in Epithelial Cells▿

PubMed Central

Gruffat, Henri; Lupo, Julien; Morand, Patrice; Boyer, Véronique; Manet, Evelyne

2011-01-01

The Epstein-Barr Virus (EBV) productive cycle is initiated by the expression of the viral trans-activator EB1 (also called Zebra, Zta, or BZLF1), which belongs to the basic leucine zipper transcription factor family. We have previously identified the cellular NACos (nuclear and adherent junction complex components) protein ubinuclein (Ubn-1) as a partner for EB1, but the function of this complex has never been studied. Here, we have evaluated the consequences of this interaction on the EBV productive cycle and find that Ubn-1 overexpression represses the EBV productive cycle whereas Ubn-1 downregulation by short hairpin RNA (shRNA) increases virus production. By a chromatin immunoprecipitation (ChIP) assay, we show that Ubn-1 blocks EB1-DNA interaction. We also show that in epithelial cells, relocalization and sequestration of Ubn-1 to the tight junctions of nondividing cells allow increased activation of the productive cycle. We propose a model in which Ubn-1 is a modulator of the EBV productive cycle: in proliferating epithelial cells, Ubn-1 is nuclear and inhibits activation of the productive cycle, whereas in differentiated cells, Ubn-1 is sequestrated to tight junctions, thereby allowing EB1 to fully function in the nucleus. PMID:21084479

Selective Effects of PD-1 on Akt and Ras Pathways Regulate Molecular Components of the Cell Cycle and Inhibit T Cell Proliferation

PubMed Central

Patsoukis, Nikolaos; Brown, Julia; Petkova, Victoria; Liu, Fang; Li, Lequn; Boussiotis, Vassiliki A.

2017-01-01

The receptor programmed death 1 (PD-1) inhibits T cell proliferation and plays a critical role in suppressing self-reactive T cells, and it also compromises antiviral and antitumor responses. To determine how PD-1 signaling inhibits T cell proliferation, we used human CD4+ T cells to examine the effects of PD-1 signaling on the molecular control of the cell cycle. The ubiquitin ligase SCFSkp2 degrades p27kip1, an inhibitor of cyclin-dependent kinases (Cdks), and PD-1 blocked cell cycle progression through the G1 phase by suppressing transcription of SKP2, which encodes a component of this ubiquitin ligase. Thus, in T cells stimulated through PD-1, Cdks were not activated, and two critical Cdk substrates were not phosphorylated. Activation of PD-1 inhibited phosphorylation of the retinoblastoma gene product, which suppressed expression of E2F target genes. PD-1 also inhibited phosphorylation of the transcription factor Smad3, which increased its activity. These events induced additional inhibitory checkpoints in the cell cycle by increasing the abundance of the G1 phase inhibitor p15INK4 and repressing the Cdk-activating phosphatase Cdc25A. PD-1 suppressed SKP2 transcription by inhibiting phosphoinositide 3-kinase–Akt and Ras–mitogen-activated and extracellular signal–regulated kinase kinase (MEK)–extracellular signal–regulated kinase (ERK) signaling. Exposure of cells to the proliferation-promoting cytokine interleukin-2 restored activation of MEK-ERK signaling, but not Akt signaling, and only partially restored SKP2 expression. Thus, PD-1 blocks cell cycle progression and proliferation of T lymphocytes by affecting multiple regulators of the cell cycle. PMID:22740686

The Giardia cell cycle progresses independently of the anaphase-promoting complex

PubMed Central

Gourguechon, Stéphane; Holt, Liam J.; Cande, W. Zacheus

2013-01-01

Summary Most cell cycle regulation research has been conducted in model organisms representing a very small part of the eukaryotic domain. The highly divergent human pathogen Giardia intestinalis is ideal for studying the conservation of eukaryotic pathways. Although Giardia has many cell cycle regulatory components, its genome lacks all anaphase-promoting complex (APC) components. In the present study, we show that a single mitotic cyclin in Giardia is essential for progression into mitosis. Strikingly, Giardia cyclin B lacks the conserved N-terminal motif required for timely degradation mediated by the APC and ubiquitin conjugation. Expression of Giardia cyclin B in fission yeast is toxic, leading to a prophase arrest, and this toxicity is suppressed by the addition of a fission yeast degradation motif. Cyclin B is degraded during mitosis in Giardia cells, but this degradation appears to be independent of the ubiquitination pathway. Other putative APC substrates, aurora and polo-like kinases, also show no evidence of ubiquitination. This is the first example of mitosis not regulated by the APC and might reflect an evolutionary ancient form of cell cycle regulation. PMID:23525017

Entrainment of the Mammalian Cell Cycle by the Circadian Clock: Modeling Two Coupled Cellular Rhythms

PubMed Central

Gérard, Claude; Goldbeter, Albert

2012-01-01

The cell division cycle and the circadian clock represent two major cellular rhythms. These two periodic processes are coupled in multiple ways, given that several molecular components of the cell cycle network are controlled in a circadian manner. For example, in the network of cyclin-dependent kinases (Cdks) that governs progression along the successive phases of the cell cycle, the synthesis of the kinase Wee1, which inhibits the G2/M transition, is enhanced by the complex CLOCK-BMAL1 that plays a central role in the circadian clock network. Another component of the latter network, REV-ERBα, inhibits the synthesis of the Cdk inhibitor p21. Moreover, the synthesis of the oncogene c-Myc, which promotes G1 cyclin synthesis, is repressed by CLOCK-BMAL1. Using detailed computational models for the two networks we investigate the conditions in which the mammalian cell cycle can be entrained by the circadian clock. We show that the cell cycle can be brought to oscillate at a period of 24 h or 48 h when its autonomous period prior to coupling is in an appropriate range. The model indicates that the combination of multiple modes of coupling does not necessarily facilitate entrainment of the cell cycle by the circadian clock. Entrainment can also occur as a result of circadian variations in the level of a growth factor controlling entry into G1. Outside the range of entrainment, the coupling to the circadian clock may lead to disconnected oscillations in the cell cycle and the circadian system, or to complex oscillatory dynamics of the cell cycle in the form of endoreplication, complex periodic oscillations or chaos. The model predicts that the transition from entrainment to 24 h or 48 h might occur when the strength of coupling to the circadian clock or the level of growth factor decrease below critical values. PMID:22693436

Investigation of cell cycle-associated structural reorganization in nucleolar FC/DFCs from mouse MFC cells by electron microscopy.

PubMed

Chen, Lingling; Jiao, Yang; Guan, Xin; Li, Xiliang; Feng, Yunpeng; Jiao, Mingda

2018-05-01

Nucleolus structure alters as the cell cycle is progressing. It is established in telophase, maintained throughout the entire interphase and disassembled in metaphase. Fibrillar centers (FCs), dense fibrillar components (DFCs) and granular components (GCs) are essential nucleolar organizations where rRNA transcription and processing and ribosome assembly take place. Hitherto, little is known about the cell cycle-dependent reorganization of these structures. In this study, we followed the nucleolus structure during the cell cycle by electron microscopy (EM). We found the nucleolus experienced multiple rounds of structural reorganization within a single cell cycle: (1) when nucleoli are formed during the transition from late M to G1 phase, FCs, DFCs and GCs are constructed, leading to the establishment of tripartite nucleolus; (2) as FC/DFCs are disrupted at mid-G1, tripartite nucleolus is gradually changed into a bipartite organization; (3) at late G1, the reassembly of FC/DFCs results in a structural transition from bipartite nucleolus towards tripartite nucleolus; (4) as cells enter S phase, FC/DFCs are disassembled again and tripartite nucleolus is thus changed into a bipartite organization. Of note, FC/DFCs were not observed until late S phase; (5) FC/DFCs experience structural disruption and restoration during G2 and (6) when cells are at mitotic stage, FC/DFCs disappear before nucleolus structure is disassembled. These results also suggest that bipartite nucleolus can exist in higher eukaryotes at certain period of the cell cycle. As structures are the fundamental basis of diverse cell activities, unveiling the structural reorganization of nucleolar FCs and DFCs may bring insights into the spatial-temporal compartmentalization of relevant cellular functions.

Modeling cell-cycle synchronization during embryogenesis in Xenopus laevis

NASA Astrophysics Data System (ADS)

McIsaac, R. Scott; Huang, K. C.; Sengupta, Anirvan; Wingreen, Ned

2010-03-01

A widely conserved aspect of embryogenesis is the ability to synchronize nuclear divisions post-fertilization. How is synchronization achieved? Given a typical protein diffusion constant of 10 μm^2sec, and an embryo length of 1mm, it would take diffusion many hours to propagate a signal across the embryo. Therefore, synchrony cannot be attained by diffusion alone. We hypothesize that known autocatalytic reactions of cell-cycle components make the embryo an ``active medium'' in which waves propagate much faster than diffusion, enforcing synchrony. We report on robust spatial synchronization of components of the core cell cycle circuit based on a mathematical model previously determined by in vitro experiments. In vivo, synchronized divisions are preceded by a rapid calcium wave that sweeps across the embryo. Experimental evidence supports the hypothesis that increases in transient calcium levels lead to derepression of a negative feedback loop, allowing cell divisions to start. Preliminary results indicate a novel relationship between the speed of the initial calcium wave and the ability to achieve synchronous cell divisions.

Gametophyte differentiation and imprinting control in plants: Crosstalk between RBR and chromatin.

PubMed

Johnston, Amal J; Gruissem, Wilhelm

2009-01-01

The Retinoblastoma (pRb) pathway has been implicated as a convergent regulatory unit in the control of cell cycle and disease. We have shown that a crosstalk between RETINOBLASTOMA RELATED (RBR), the Arabidopsis homologue of pRb, and the genes encoding proteins of the chromatin complexes involved in DNA or histone methylation, controls gametophytic and post-fertilization differentiation events and a subset of imprinting effects. We describe here a plausible model that incorporates several components of the plant Retinoblastoma pathway, thus offering a novel paradigm that merges the traditional cell cycle and the chromatin components in the control of cell differentiation and imprinting.

Antitumor action of 3-bromopyruvate implicates reorganized tumor growth regulatory components of tumor milieu, cell cycle arrest and induction of mitochondria-dependent tumor cell death.

PubMed

Yadav, Saveg; Kujur, Praveen Kumar; Pandey, Shrish Kumar; Goel, Yugal; Maurya, Babu Nandan; Verma, Ashish; Kumar, Ajay; Singh, Rana Pratap; Singh, Sukh Mahendra

2018-01-15

Evidences demonstrate that metabolic inhibitor 3-bromopyruvate (3-BP) exerts a potent antitumor action against a wide range of malignancies. However, the effect of 3-BP on progression of the tumors of thymic origin remains unexplored. Although, constituents of tumor microenvironment (TME) plays a pivotal role in regulation of tumor progression, it remains unclear if 3-BP can alter the composition of the crucial tumor growth regulatory components of the external surrounding of tumor cells. Thus, the present investigation attempts to understand the effect of 3-BP administration to a host bearing a progressively growing tumor of thymic origin on tumor growth regulatory soluble, cellular and biophysical components of tumor milieu vis-à-vis understanding its association with tumor progression, accompanying cell cycle events and mode of cell death. Further, the expression of cell survival regulatory molecules and hemodynamic characteristics of the tumor milieu were analysed to decipher mechanisms underlying the antitumor action of 3-BP. Administration of 3-BP to tumor-bearing hosts retarded tumor progression accompanied by induction of tumor cell death, cell cycle arrest, declined metabolism, inhibited mitochondrial membrane potential, elevated release of cytochrome c and altered hemodynamics. Moreover, 3-BP reconstituted the external milieu, in concurrence with deregulated glucose and pH homeostasis and increased tumor infiltration by NK cells, macrophages, and T lymphocytes. Further, 3-BP administration altered the expression of key regulatory molecules involved in glucose uptake, intracellular pH and tumor cell survival. The outcomes of this study will help in optimizing the therapeutic application of 3-BP by targeting crucial tumor growth regulatory components of tumor milieu. Copyright © 2017 Elsevier Inc. All rights reserved.

A mathematical model for predicting the life of polymer electrolyte fuel cell membranes subjected to hydration cycling

NASA Astrophysics Data System (ADS)

Burlatsky, S. F.; Gummalla, M.; O'Neill, J.; Atrazhev, V. V.; Varyukhin, A. N.; Dmitriev, D. V.; Erikhman, N. S.

2012-10-01

Under typical Polymer Electrolyte Membrane Fuel Cell (PEMFC) fuel cell operating conditions, part of the membrane electrode assembly is subjected to humidity cycling due to variation of inlet gas RH and/or flow rate. Cyclic membrane hydration/dehydration would cause cyclic swelling/shrinking of the unconstrained membrane. In a constrained membrane, it causes cyclic stress resulting in mechanical failure in the area adjacent to the gas inlet. A mathematical modeling framework for prediction of the lifetime of a PEMFC membrane subjected to hydration cycling is developed in this paper. The model predicts membrane lifetime as a function of RH cycling amplitude and membrane mechanical properties. The modeling framework consists of three model components: a fuel cell RH distribution model, a hydration/dehydration induced stress model that predicts stress distribution in the membrane, and a damage accrual model that predicts membrane lifetime. Short descriptions of the model components along with overall framework are presented in the paper. The model was used for lifetime prediction of a GORE-SELECT membrane.

Do lipids shape the eukaryotic cell cycle?

PubMed

Furse, Samuel; Shearman, Gemma C

2018-01-01

Successful passage through the cell cycle presents a number of structural challenges to the cell. Inceptive studies carried out in the last five years have produced clear evidence of modulations in the lipid profile (sometimes referred to as the lipidome) of eukaryotes as a function of the cell cycle. This mounting body of evidence indicates that lipids play key roles in the structural transformations seen across the cycle. The accumulation of this evidence coincides with a revolution in our understanding of how lipid composition regulates a plethora of biological processes ranging from protein activity through to cellular signalling and membrane compartmentalisation. In this review, we discuss evidence from biological, chemical and physical studies of the lipid fraction across the cell cycle that demonstrate that lipids are well-developed cellular components at the heart of the biological machinery responsible for managing progress through the cell cycle. Furthermore, we discuss the mechanisms by which this careful control is exercised. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

Natural Compounds as Modulators of Cell Cycle Arrest: Application for Anticancer Chemotherapies

PubMed Central

Bailon-Moscoso, Natalia; Cevallos-Solorzano, Gabriela; Romero-Benavides, Juan Carlos; Orellana, Maria Isabel Ramirez

2017-01-01

Natural compounds from various plants, microorganisms and marine species play an important role in the discovery novel components that can be successfully used in numerous biomedical applications, including anticancer therapeutics. Since uncontrolled and rapid cell division is a hallmark of cancer, unraveling the molecular mechanisms underlying mitosis is key to understanding how various natural compounds might function as inhibitors of cell cycle progression. A number of natural compounds that inhibit the cell cycle arrest have proven effective for killing cancer cells in vitro, in vivo and in clinical settings. Significant advances that have been recently made in the understanding of molecular mechanisms underlying the cell cycle regulation using the chemotherapeutic agents is of great importance for improving the efficacy of targeted therapeutics and overcoming resistance to anticancer drugs, especially of natural origin, which inhibit the activities of cyclins and cyclin-dependent kinases, as well as other proteins and enzymes involved in proper regulation of cell cycle leading to controlled cell proliferation. PMID:28367072

The circadian molecular clock regulates adult hippocampal neurogenesis by controlling the timing of cell-cycle entry and exit.

PubMed

Bouchard-Cannon, Pascale; Mendoza-Viveros, Lucia; Yuen, Andrew; Kærn, Mads; Cheng, Hai-Ying M

2013-11-27

The subgranular zone (SGZ) of the adult hippocampus contains a pool of quiescent neural progenitor cells (QNPs) that are capable of entering the cell cycle and producing newborn neurons. The mechanisms that control the timing and extent of adult neurogenesis are not well understood. Here, we show that QNPs of the adult SGZ express molecular-clock components and proliferate in a rhythmic fashion. The clock proteins PERIOD2 and BMAL1 are critical for proper control of neurogenesis. The absence of PERIOD2 abolishes the gating of cell-cycle entrance of QNPs, whereas genetic ablation of bmal1 results in constitutively high levels of proliferation and delayed cell-cycle exit. We use mathematical model simulations to show that these observations may arise from clock-driven expression of a cell-cycle inhibitor that targets the cyclin D/Cdk4-6 complex. Our findings may have broad implications for the circadian clock in timing cell-cycle events of other stem cell populations throughout the body. Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.

Advanced Lithium-Ion Cell Development for NASA's Constellation Missions

NASA Technical Reports Server (NTRS)

Reid, Concha M.; Miller, Thomas B.; Manzo, Michelle A.; Mercer, Carolyn R.

2008-01-01

The Energy Storage Project of NASA s Exploration Technology Development Program is developing advanced lithium-ion batteries to meet the requirements for specific Constellation missions. NASA GRC, in conjunction with JPL and JSC, is leading efforts to develop High Energy and Ultra High Energy cells for three primary Constellation customers: Altair, Extravehicular Activities (EVA), and Lunar Surface Systems. The objective of the High Energy cell development is to enable a battery system that can operationally deliver approximately 150 Wh/kg for 2000 cycles. The Ultra High Energy cell development will enable a battery system that can operationally deliver 220 Wh/kg for 200 cycles. To accomplish these goals, cathode, electrolyte, separator, and safety components are being developed for High Energy Cells. The Ultra High Energy cell development adds lithium alloy anodes to the component development portfolio to enable much higher cell-level specific energy. The Ultra High Energy cell development is targeted for the ascent stage of Altair, which is the Lunar Lander, and for power for the Portable Life support System of the EVA Lunar spacesuit. For these missions, mass is highly critical, but only a limited number of cycles are required. The High Energy cell development is primarily targeted for Mobility Systems (rovers) for Lunar Surface Systems, however, due to the high risk nature of the Ultra High Energy cell development, the High Energy cell will also serve as a backup technology for Altair and EVA. This paper will discuss mission requirements and the goals of the material, component, and cell development efforts in further detail.

Changes of Constituents and Activity to Apoptosis and Cell Cycle During Fermentation of Tea

PubMed Central

Zhao, Hang; Zhang, Min; Zhao, Lu; Ge, Ya-kun; Sheng, Jun; Shi, Wei

2011-01-01

Tea is believed to be beneficial for health, and the effects of the fermentation process on its contributions to apoptosis and cell cycle arrest of gastric cancer cells have not been completely investigated. In this study, the chemical components in green tea, black tea and pu-erh tea aqueous extracts were analyzed and compared. The polysaccharide and caffeine levels were substantially higher in the fermented black tea and pu-erh tea, while the polyphenol level was higher in the unfermented green tea. Hence, a treatment of tea aqueous extract and the components, which are emerging as promising anticancer agents, were pursued to determine whether this treatment could lead to enhance apoptosis and cell cycle arrest. In the human gastric cancer cell line SGC-7901, the cell viability and flow cytometry analysis for apoptotic cells indicated effects in a dose-dependent inhibition manner for the three tea treatment groups. The apoptosis rates were found to be elevated after 48 h of treatment with 31.2, 125, and 500 μg/mL of green tea extract, the higher catechins content may be involved in the mechanism. Cell cycle was arrested in S phase in the fermented black tea and pu-erh tea, and the populations were significantly decreased in G2/M phases, possibly due to the oxidation of tea polyphenols, which causes an increase of theabrownins. CCC-HEL-1 normal cells were not sensitive to tea extract. These findings suggest that the fermentation process causes changes of the compounds which might be involved in the changes of cell proliferation inhibition, apoptosis induction and cell cycle arrest. PMID:21673927

Changes of constituents and activity to apoptosis and cell cycle during fermentation of tea.

PubMed

Zhao, Hang; Zhang, Min; Zhao, Lu; Ge, Ya-Kun; Sheng, Jun; Shi, Wei

2011-01-01

Tea is believed to be beneficial for health, and the effects of the fermentation process on its contributions to apoptosis and cell cycle arrest of gastric cancer cells have not been completely investigated. In this study, the chemical components in green tea, black tea and pu-erh tea aqueous extracts were analyzed and compared. The polysaccharide and caffeine levels were substantially higher in the fermented black tea and pu-erh tea, while the polyphenol level was higher in the unfermented green tea. Hence, a treatment of tea aqueous extract and the components, which are emerging as promising anticancer agents, were pursued to determine whether this treatment could lead to enhance apoptosis and cell cycle arrest. In the human gastric cancer cell line SGC-7901, the cell viability and flow cytometry analysis for apoptotic cells indicated effects in a dose-dependent inhibition manner for the three tea treatment groups. The apoptosis rates were found to be elevated after 48 h of treatment with 31.2, 125, and 500 μg/mL of green tea extract, the higher catechins content may be involved in the mechanism. Cell cycle was arrested in S phase in the fermented black tea and pu-erh tea, and the populations were significantly decreased in G2/M phases, possibly due to the oxidation of tea polyphenols, which causes an increase of theabrownins. CCC-HEL-1 normal cells were not sensitive to tea extract. These findings suggest that the fermentation process causes changes of the compounds which might be involved in the changes of cell proliferation inhibition, apoptosis induction and cell cycle arrest.

Indigo naturalis and its component tryptanthrin exert anti-angiogenic effect by arresting cell cycle and inhibiting Akt and FAK signaling in human vascular endothelial cells.

PubMed

Chang, Hsin-Ning; Huang, Sheng-Teng; Yeh, Yuan-Chieh; Wang, Hsin-Shih; Wang, Tzu-Hao; Wu, Yi-Hong; Pang, Jong-Hwei S

2015-11-04

Indigo naturalis has been used to treat inflammatory diseases and dermatosis, including psoriasis, since thousands of years in China. It has been proven effective in our previous clinical studies on treating psoriasis, but the active component and the mechanism of how indigo naturalis working still needs to be clarified. Since the dysregulated angiogenesis is known to play an important role in the pathogenesis of psoriasis, the anti-angiogenic effect of indigo naturalis and tryptanthrin, a pure component of indigo naturalis, was investigated. The in vivo angiogenesis was studied by chick chorioallantoic membrane assay. The in vitro studies were performed using human vascular endothelial cells. Cell viability was determined by MTT assay. Cell cycle distribution was revealed by flow cytometry. The cellular messenger (m)RNA or protein expression level was analyzed by real-time RT-PCR or Western blot, respectively. Transwell filter migration assay and matrix gel-induced tube formation method were applied to examine the angiogenic potential. Indigo naturalis significantly inhibited the in vivo vascular endothelial growth factor (VEGF)-induced angiogenesis, as well as tryptanthrin. In vitro studies confirmed that indigo naturalis and tryptanthrin reduced the number of viable vascular endothelial cells. Tryptanthrin resulted in a cell cycle arrest and dose-dependently decreased the expressions of cyclin A, cyclin B, cyclin dependent kinase(CDK) 1 and 2, but not cyclin D and cyclin E, at both the mRNA and protein levels. The migration and tube formation of vascular endothelial cells were significantly inhibited by tryptanthrin in a dose-dependent manner. Result also showed that tryptanthrin could reduce the phosphorylated levels of both protein kinase B (PKB or Akt) and focal adhesion kinase (FAK). All together, these results demonstrated the anti-angiogenic effect of tryptanthrin, the acting component of indigo naturalis and revealed the underlying mechanism by inhibiting the cell cycle progression, cell migration and tube formation, likely mediated through blocking the Akt and FAK pathways. Copyright © 2015 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

Centromere Transcription: Means and Motive.

PubMed

Duda, Zachary; Trusiak, Sarah; O'Neill, Rachel

2017-01-01

The chromosome biology field at large has benefited from studies of the cell cycle components, protein cascades and genomic landscape that are required for centromere identity, assembly and stable transgenerational inheritance. Research over the past 20 years has challenged the classical descriptions of a centromere as a stable, unmutable, and transcriptionally silent chromosome component. Instead, based on studies from a broad range of eukaryotic species, including yeast, fungi, plants, and animals, the centromere has been redefined as one of the more dynamic areas of the eukaryotic genome, requiring coordination of protein complex assembly, chromatin assembly, and transcriptional activity in a cell cycle specific manner. What has emerged from more recent studies is the realization that the transcription of specific types of nucleic acids is a key process in defining centromere integrity and function. To illustrate the transcriptional landscape of centromeres across eukaryotes, we focus this review on how transcripts interact with centromere proteins, when in the cell cycle centromeric transcription occurs, and what types of sequences are being transcribed. Utilizing data from broadly different organisms, a picture emerges that places centromeric transcription as an integral component of centromere function.

Molecular basis of cell integrity and morphogenesis in Saccharomyces cerevisiae.

PubMed Central

Cid, V J; Durán, A; del Rey, F; Snyder, M P; Nombela, C; Sánchez, M

1995-01-01

In fungi and many other organisms, a thick outer cell wall is responsible for determining the shape of the cell and for maintaining its integrity. The budding yeast Saccharomyces cerevisiae has been a useful model organism for the study of cell wall synthesis, and over the past few decades, many aspects of the composition, structure, and enzymology of the cell wall have been elucidated. The cell wall of budding yeasts is a complex and dynamic structure; its arrangement alters as the cell grows, and its composition changes in response to different environmental conditions and at different times during the yeast life cycle. In the past few years, we have witnessed a profilic genetic and molecular characterization of some key aspects of cell wall polymer synthesis and hydrolysis in the budding yeast. Furthermore, this organism has been the target of numerous recent studies on the topic of morphogenesis, which have had an enormous impact on our understanding of the intracellular events that participate in directed cell wall synthesis. A number of components that direct polarized secretion, including those involved in assembly and organization of the actin cytoskeleton, secretory pathways, and a series of novel signal transduction systems and regulatory components have been identified. Analysis of these different components has suggested pathways by which polarized secretion is directed and controlled. Our aim is to offer an overall view of the current understanding of cell wall dynamics and of the complex network that controls polarized growth at particular stages of the budding yeast cell cycle and life cycle. PMID:7565410

Vertebrate Cell Cycle Modulates Infection by Protozoan Parasites

NASA Astrophysics Data System (ADS)

Dvorak, James A.; Crane, Mark St. J.

1981-11-01

Synchronized HeLa cell populations were exposed to Trypanosoma cruzi or Toxoplasma gondii, obligate intracellular protozoan parasites that cause Chagas' disease and toxoplasmosis, respectively, in humans. The ability of the two parasites to infect HeLa cells increased as the HeLa cells proceeded from the G1 phase to the S phase of their growth cycle and decreased as the cells entered G2-M. Characterization of the S-phase cell surface components responsible for this phenomenon could be beneficial in the development of vaccines against these parasitic diseases.

14CO2 INCORPORATION INTO THE NUCLEIC ACIDS OF SYNCHRONOUSLYGROWING CHLORELLA CELLS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stange, Luise; Kirk, Martha; Bennett, Edward L

1962-03-08

A study of the incorporation of {sup 14}CO{sub 2} into cell components of synchronously growing Chlorella pyrenoidosa has shown that DNA is synthesized primarily during the latter stages of the cell cycle prior to cell division. RNA was synthesized at an approximately equal rate during each of the three phases of the cell growth studied. No major differences were noted in the incorporation of {sup 14}CO{sub 2} into the soluble cell components in these long-term incorporation studies.

KOH concentration effect on the cycle life of nickel-hydrogen cells. 4: Results of failure analyse

NASA Technical Reports Server (NTRS)

Lim, H. S.; Verzwyvelt, S. A.

1989-01-01

Effects of KOH concentrations on failure modes and mechanisms of nickel-hydrogen cells were studied using long cycled boiler plate cells containing electrolytes of various KOH concentrations ranging 21 to 36 percent. Life of these cells were up to 40,000 cycles in an accelerated low earth orbit (LEO) cycle regime at 80 percent depth of discharge. An interim life test results were reported earlier in J. Power Sources, 22, 213-220, 1988. The results of final life test, end-of-life cell performance, and teardown analyses are discussed. These teardown analyses included visual observations, measurements of nickel electrode capacity in an electrolyte-flooded cell, dimensional changes of cell components, SEM studies on cell cross section, BET surface area and pore volume distribution in cycled nickel electrodes, and chemical analyses. Cycle life of a nickel-hydrogen cell was improved tremendously as KOH concentration was decreased from 36 to 31 percent and from 31 to 26 percent while effect of further concentration decrease was complicated as described in our earlier report. Failure mode of high concentration (31 to 36 percent) cells was gradual capacity decrease, while that of low concentration (21 to 26 percent) cells was mainly formation of a soft short. Long cycled (25,000 to 40,000 cycles) nickel electrodes were expanded more than 50 percent of the initial value, but no correlation was found between this expansion and measured capacity. All electrodes cycled in low concentration (21 to 26 percent) cells had higher capacity than those cycled in high concentration (31 to 36 percent) cells.

Cell cycle behavior of laboratory and field populations of the Florida red tide dinoflagellate, Karenia brevis

NASA Astrophysics Data System (ADS)

Van Dolah, Frances M.; Leighfield, Tod A.; Kamykowski, Daniel; Kirkpatrick, Gary J.

2008-01-01

As a component of the ECOHAB Florida Regional Field Program, this study addresses cell cycle behavior and its importance to bloom formation of the Florida red tide dinoflagellate, Karenia brevis. The cell cycle of K. brevis was first studied by flow cytometry in laboratory batch cultures, and a laboratory mesocosm column, followed by field populations over the 5-year course of the ECOHAB program. Under all conditions studied, K. brevis displayed diel phased cell division with S-phase beginning a minimum of 6 h after the onset of light and continuing for 12-14 h. Mitosis occurred during the dark, and was generally completed by the start of the next day. The timing of cell cycle phases relative to the diel cycle did not differ substantially in bloom populations displaying radically different growth rates ( μmin 0.17-0.55) under different day lengths and temperature conditions. The rhythm of cell cycle progression is independent from the rhythm controlling vertical migration, as similar cell cycle distributions are found at all depths of the water column in field samples. The implications of these findings are discussed in light of our current understanding of the dinoflagellate cell cycle and the development of improved models for K. brevis bloom growth.

High Energy Density Li-ion Cells for EV’s Based on Novel, High Voltage Cathode Material Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kepler, Keith D.; Slater, Michael

This Li-ion cell technology development project had three objectives: to develop advanced electrode materials and cell components to enable stable high-voltage operation; to design and demonstrate a Li-ion cell using these materials that meets the PHEV40 performance targets; and to design and demonstrate a Li-ion cell using these materials that meets the EV performance targets. The major challenge to creating stable high energy cells with long cycle life is system integration. Although materials that can give high energy cells are known, stabilizing them towards long-term cycling in the presence of other novel cell components is a major challenge. The majormore » technical barriers addressed by this work include low cathode specific energy, poor electrolyte stability during high voltage operation, and insufficient capacity retention during deep discharge for Si-containing anodes. Through the course of this project, Farasis was able to improve capacity retention of NCM materials for 4.4+ V operation, through both surface treatment and bulk-doping approaches. Other material advances include increased rate capability and of HE-NCM materials through novel synthesis approach, doubling the relative capacity at 1C over materials synthesized using standard methods. Silicon active materials proved challenging throughout the project and ultimately were the limiting factor in the energy density vs. cycle life trade off. By avoiding silicon anodes for the lower energy PHEV design, we manufactured cells with intermediate energy density and long cycle life under high voltage operation for PHEV applications. Cells with high energy density for EV applications were manufactured targeting a 300 Wh/kg design and were able to achieve > 200 cycles.« less

Corrosion of stainless steel battery components by bis(fluorosulfonyl)imide based ionic liquid electrolytes

NASA Astrophysics Data System (ADS)

Evans, Tyler; Olson, Jarred; Bhat, Vinay; Lee, Se-Hee

2014-12-01

While the anodic behavior of aluminum foil current collectors in imide-based room temperature ionic liquids (RTILs) is relatively well understood, interactions between such RTILs and other passive battery components have not been studied extensively. This study presents the solvent and potential dependent oxidation of SS316 coin-cell components in the N-methyl-N-propyl-pyrrolidinium bis(fluorosulfonyl)imide (PYR13FSI) RTIL. While this phenomenon prohibits high-voltage cycling of Li(Ni1/3Mn1/3Co1/3)O2 cathodes in SS316 coin-type cells, Al-clad cell components or alternative cell configurations can be utilized to avoid SS316 oxidation-induced cell failure.

Suppression of tumor growth by Pleurotus ferulae ethanol extract through induction of cell apoptosis, and inhibition of cell proliferation and migration.

PubMed

Wang, Weilan; Chen, Kaixu; Liu, Qing; Johnston, Nathan; Ma, Zhenghai; Zhang, Fuchun; Zheng, Xiufen

2014-01-01

Cancer is the second leading cause of death worldwide. Edible medicinal mushrooms have been used in traditional medicine as regimes for cancer patients. Recently anti-cancer bioactive components from some mushrooms have been isolated and their anti-cancer effects have been tested. Pleurotus ferulae, a typical edible medicinal mushroom in Xinjiang China, has also been used to treat cancer patients in folk medicine. However, little studies have been reported on the anti-cancer components of Pleurotus ferulae. This study aims to extract bioactive components from Pleurotus ferulae and to investigate the anti-cancer effects of the extracts. We used ethanol to extract anti-cancer bioactive components enriched with terpenoids from Pleurotus ferulae. We tested the anti-tumour effects of ethanol extracts on the melanoma cell line B16F10, the human gastric cancer cell line BGC 823 and the immortalized human gastric epithelial mucosa cell line GES-1 in vitro and a murine melanoma model in vivo. Cell toxicity and cell proliferation were measured by MTT assays. Cell cycle progression, apoptosis, caspase 3 activity, mitochondrial membrane potential (MMP), migration and gene expression were studied in vitro. PFEC suppressed tumor cell growth, inhibited cell proliferation, arrested cells at G0/G1 phases and was not toxic to non-cancer cells. PFEC also induced cell apoptosis and necrosis, increased caspase 3 activity, reduced the MMP, prevented cell invasion and changed the expression of genes associated with apoptosis and the cell cycle. PFEC delayed tumor formation and reduced tumor growth in vivo. In conclusion, ethanol extracted components from Pleurotus ferulae exert anti-cancer effects through direct suppression of tumor cell growth and invasion, demonstrating its therapeutic potential in cancer treatment.

A Krebs Cycle Component Limits Caspase Activation Rate through Mitochondrial Surface Restriction of CRL Activation.

PubMed

Aram, Lior; Braun, Tslil; Braverman, Carmel; Kaplan, Yosef; Ravid, Liat; Levin-Zaidman, Smadar; Arama, Eli

2016-04-04

How cells avoid excessive caspase activity and unwanted cell death during apoptotic caspase-mediated removal of large cellular structures is poorly understood. We investigate caspase-mediated extrusion of spermatid cytoplasmic contents in Drosophila during spermatid individualization. We show that a Krebs cycle component, the ATP-specific form of the succinyl-CoA synthetase β subunit (A-Sβ), binds to and activates the Cullin-3-based ubiquitin ligase (CRL3) complex required for caspase activation in spermatids. In vitro and in vivo evidence suggests that this interaction occurs on the mitochondrial surface, thereby limiting the source of CRL3 complex activation to the vicinity of this organelle and reducing the potential rate of caspase activation by at least 60%. Domain swapping between A-Sβ and the GTP-specific SCSβ (G-Sβ), which functions redundantly in the Krebs cycle, show that the metabolic and structural roles of A-Sβ in spermatids can be uncoupled, highlighting a moonlighting function of this Krebs cycle component in CRL activation. Copyright © 2016 Elsevier Inc. All rights reserved.

Influence of temperature on the aging behavior of 18650-type lithium ion cells: A comprehensive approach combining electrochemical characterization and post-mortem analysis

NASA Astrophysics Data System (ADS)

Friesen, Alex; Mönnighoff, Xaver; Börner, Markus; Haetge, Jan; Schappacher, Falko M.; Winter, Martin

2017-02-01

The understanding of the aging behavior of lithium ion batteries in automotive and energy storage applications is essential for the acceptance of the technology. Therefore, aging experiments were conducted on commercial 18650-type state-of-the-art cells to determine the influence of the temperature during electrochemical cycling on the aging behavior of the different cell components. The cells, based on Li(Ni0.5Co0.2Mn0.3)O2 (NCM532)/graphite, were aged at 20 °C and 45 °C to different states of health. The electrochemical performance of the investigated cells shows remarkable differences depending on the cycling temperature. At contrast to the expected behavior, the cells cycled at 45 °C show a better electrochemical performance over lifetime than the cells cycled at 20 °C. Comprehensive post-mortem analyses revealed the main aging mechanisms, showing a complex interaction between electrodes and electrolyte. The main aging mechanisms of the cells cycled at 45 °C differ strongly at contrast to cells cycled at 20 °C. A strong correlation between the formed SEI, the electrolyte composition and the electrochemical performance over lifetime was observed.

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

PubMed

Juanes, Maria Angeles; Piatti, Simonetta

2016-08-01

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

Integrative Analysis Reveals an Outcome-associated and Targetable Pattern of p53 and Cell Cycle Deregulation in Diffuse Large B-cell Lymphoma

PubMed Central

Monti, Stefano; Chapuy, Bjoern; Takeyama, Kunihiko; Rodig, Scott J; Hao, Yangsheng; Yeda, Kelly T.; Inguilizian, Haig; Mermel, Craig; Curie, Treeve; Dogan, Ahmed; Kutok, Jeffery L; Beroukim, Rameen; Neuberg, Donna; Habermann, Thomas; Getz, Gad; Kung, Andrew L; Golub, Todd R; Shipp, Margaret A

2013-01-01

Summary Diffuse large B-cell lymphoma (DLBCL) is a clinically and biologically heterogeneous disease with a high proliferation rate. By integrating copy number data with transcriptional profiles and performing pathway analysis in primary DLBCLs, we identified a comprehensive set of copy number alterations (CNAs) that decreased p53 activity and perturbed cell cycle regulation. Primary tumors either had multiple complementary alterations of p53 and cell cycle components or largely lacked these lesions. DLBCLs with p53 and cell cycle pathway CNAs had decreased abundance of p53 target transcripts and increased expression of E2F target genes and the Ki67 proliferation marker. CNAs of the CDKN2A-TP53-RB-E2F axis provide a structural basis for increased proliferation in DLBCL, predict outcome with current therapy and suggest targeted treatment approaches. PMID:22975378

Roles for the Histone Modifying and Exchange Complex NuA4 in Cell Cycle Progression in Drosophila melanogaster.

PubMed

Flegel, Kerry; Grushko, Olga; Bolin, Kelsey; Griggs, Ellen; Buttitta, Laura

2016-07-01

Robust and synchronous repression of E2F-dependent gene expression is critical to the proper timing of cell cycle exit when cells transition to a postmitotic state. Previously NuA4 was suggested to act as a barrier to proliferation in Drosophila by repressing E2F-dependent gene expression. Here we show that NuA4 activity is required for proper cell cycle exit and the repression of cell cycle genes during the transition to a postmitotic state in vivo However, the delay of cell cycle exit caused by compromising NuA4 is not due to additional proliferation or effects on E2F activity. Instead NuA4 inhibition results in slowed cell cycle progression through late S and G2 phases due to aberrant activation of an intrinsic p53-independent DNA damage response. A reduction in NuA4 function ultimately produces a paradoxical cell cycle gene expression program, where certain cell cycle genes become derepressed in cells that are delayed during the G2 phase of the final cell cycle. Bypassing the G2 delay when NuA4 is inhibited leads to abnormal mitoses and results in severe tissue defects. NuA4 physically and genetically interacts with components of the E2F complex termed D: rosophila, R: bf, E: 2F A: nd M: yb/ M: ulti-vulva class B: (DREAM/MMB), and modulates a DREAM/MMB-dependent ectopic neuron phenotype in the posterior wing margin. However, this effect is also likely due to the cell cycle delay, as simply reducing Cdk1 is sufficient to generate a similar phenotype. Our work reveals that the major requirement for NuA4 in the cell cycle in vivo is to suppress an endogenous DNA damage response, which is required to coordinate proper S and G2 cell cycle progression with differentiation and cell cycle gene expression. Copyright © 2016 by the Genetics Society of America.

Roles for the Histone Modifying and Exchange Complex NuA4 in Cell Cycle Progression in Drosophila melanogaster

PubMed Central

Flegel, Kerry; Grushko, Olga; Bolin, Kelsey; Griggs, Ellen; Buttitta, Laura

2016-01-01

Robust and synchronous repression of E2F-dependent gene expression is critical to the proper timing of cell cycle exit when cells transition to a postmitotic state. Previously NuA4 was suggested to act as a barrier to proliferation in Drosophila by repressing E2F-dependent gene expression. Here we show that NuA4 activity is required for proper cell cycle exit and the repression of cell cycle genes during the transition to a postmitotic state in vivo. However, the delay of cell cycle exit caused by compromising NuA4 is not due to additional proliferation or effects on E2F activity. Instead NuA4 inhibition results in slowed cell cycle progression through late S and G2 phases due to aberrant activation of an intrinsic p53-independent DNA damage response. A reduction in NuA4 function ultimately produces a paradoxical cell cycle gene expression program, where certain cell cycle genes become derepressed in cells that are delayed during the G2 phase of the final cell cycle. Bypassing the G2 delay when NuA4 is inhibited leads to abnormal mitoses and results in severe tissue defects. NuA4 physically and genetically interacts with components of the E2F complex termed Drosophila, Rbf, E2F and Myb/Multi-vulva class B (DREAM/MMB), and modulates a DREAM/MMB-dependent ectopic neuron phenotype in the posterior wing margin. However, this effect is also likely due to the cell cycle delay, as simply reducing Cdk1 is sufficient to generate a similar phenotype. Our work reveals that the major requirement for NuA4 in the cell cycle in vivo is to suppress an endogenous DNA damage response, which is required to coordinate proper S and G2 cell cycle progression with differentiation and cell cycle gene expression. PMID:27184390

Dynamics of tobacco DNA topoisomerases II in cell cycle regulation: to manage topological constrains during replication, transcription and mitotic chromosome condensation and segregation.

PubMed

Singh, Badri Nath; Achary, V Mohan Murali; Panditi, Varakumar; Sopory, Sudhir K; Reddy, Malireddy K

2017-08-01

The topoisomerase II expression varies as a function of cell proliferation. Maximal topoisomerase II expression was tightly coupled to S phase and G2/M phase via both transcriptional and post-transcriptional regulation. Investigation in meiosis using pollen mother cells also revealed that it is not the major component of meiotic chromosomes, it seems to diffuse out once meiotic chromosomal condensation is completed. Synchronized tobacco BY-2 cell cultures were used to study the role of topoisomerase II in various stages of the cell cycle. Topoisomerase II transcript accumulation was observed during the S- and G2/M- phase of cell cycle. This biphasic expression pattern indicates the active requirement of topoisomerase II during these stages of the cell cycle. Through immuno-localization of topoisomerase II was observed diffusely throughout the nucleoplasm in interphase nuclei, whereas, the nucleolus region exhibited a more prominent immuno-positive staining that correlated with rRNA transcription, as shown by propidium iodide staining and BrUTP incorporation. The immuno-staining analysis also showed that topoisomerase II is the major component of mitotic chromosomes and remain attached to the chromosomes during cell division. The inhibition of topoisomerase II activity using specific inhibitors revealed quite dramatic effect on condensation of chromatin and chromosome individualization from prophase to metaphase transition. Partially condensed chromosomes were not arranged on metaphase plate and chromosomal perturbations were observed when advance to anaphase, suggesting the importance of topoisomerase II activity for proper chromosome condensation and segregation during mitosis. Contrary, topoisomerase II is not the major component of meiotic chromosomes, even though mitosis and meiosis share many processes, including the DNA replication, chromosome condensation and precisely regulated partitioning of chromosomes into daughter cells. Even if topoisomerase II is required for individualization and condensation of meiotic chromosomes, it seems to diffuse out once meiotic chromosomal condensation is completed.

The BMI1 inhibitor PTC-209 is a potential compound to halt cellular growth in biliary tract cancer cells

PubMed Central

Mayr, Christian; Wagner, Andrej; Loeffelberger, Magdalena; Bruckner, Daniela; Jakab, Martin; Berr, Frieder; Di Fazio, Pietro; Ocker, Matthias; Neureiter, Daniel; Pichler, Martin; Kiesslich, Tobias

2016-01-01

BMI1 is a core component of the polycomb repressive complex 1 (PRC1) and is up-regulated in biliary tract cancer (BTC), contributing to aggressive clinical features. In this study we investigated the cytotoxic effects of PTC-209, a recently developed inhibitor of BMI1, in BTC cells. PTC-209 reduced overall viability in BTC cell lines in a dose-dependent fashion (0.04 - 20 μM). Treatment with PTC-209 led to slightly enhanced caspase activity and stop of cell proliferation. Cell cycle analysis revealed that PTC-209 caused cell cycle arrest at the G1/S checkpoint. A comprehensive investigation of expression changes of cell cycle-related genes showed that PTC-209 caused significant down-regulation of cell cycle-promoting genes as well as of genes that contribute to DNA synthesis initiation and DNA repair, respectively. This was accompanied by significantly elevated mRNA levels of cell cycle inhibitors. In addition, PTC-209 reduced sphere formation and, in a cell line-dependent manner, aldehyde dehydrogease-1 positive cells. We conclude that PTC-209 might be a promising drug for future in vitro and in vivo studies in BTC. PMID:26623561

Expression of Progesterone Receptor Membrane Component-2 Within the Immature Rat Ovary and Its Role in Regulating Mitosis and Apoptosis of Spontaneously Immortalized Granulosa Cells1

PubMed Central

Griffin, Daniel; Liu, Xiufang; Pru, Cindy; Pru, James K.; Peluso, John J.

2014-01-01

ABSTRACT Progesterone receptor membrane component 2 (Pgrmc2) mRNA was detected in the immature rat ovary. By 48 h after eCG, Pgrmc2 mRNA levels decreased by 40% and were maintained at 48 h post-hCG. Immunohistochemical studies detected PGRMC2 in oocytes and ovarian surface epithelial, interstitial, thecal, granulosa, and luteal cells. PGRMC2 was also present in spontaneously immortalized granulosa cells, localizing to the cytoplasm of interphase cells and apparently to the mitotic spindle of cells in metaphase. Interestingly, PGRMC2 levels appeared to decrease during the G1 stage of the cell cycle. Moreover, overexpression of PGRMC2 suppressed entry into the cell cycle, possibly by binding the p58 form of cyclin dependent kinase 11b. Conversely, Pgrmc2 small interfering RNA (siRNA) treatment increased the percentage of cells in G1 and M stage but did not increase the number of cells, which was likely due to an increase in apoptosis. Depleting PGRMC2 did not inhibit cellular 3H-progesterone binding, but attenuated the ability of progesterone to suppress mitosis and apoptosis. Taken together these studies suggest that PGRMC2 affects granulosa cell mitosis by acting at two specific stages of the cell cycle. First, PGRMC2 regulates the progression from the G0 into the G1 stage of the cell cycle. Second, PGRMC2 appears to localize to the mitotic spindle, where it likely promotes the final stages of mitosis. Finally, siRNA knockdown studies indicate that PGRMC2 is required for progesterone to slow the rate of granulosa cell mitosis and apoptosis. These findings support a role for PGRMC2 in ovarian follicle development. PMID:24990806

Pathobiology of Pneumocystis pneumonia: life cycle, cell wall and cell signal transduction.

PubMed

Skalski, Joseph H; Kottom, Theodore J; Limper, Andrew H

2015-09-01

Pneumocystis is a genus of ascomycetous fungi that are highly morbid pathogens in immunosuppressed humans and other mammals. Pneumocystis cannot easily be propagated in culture, which has greatly hindered understanding of its pathobiology. The Pneumocystis life cycle is intimately associated with its mammalian host lung environment, and life cycle progression is dependent on complex interactions with host alveolar epithelial cells and the extracellular matrix. The Pneumocystis cell wall is a varied and dynamic structure containing a dominant major surface glycoprotein, β-glucans and chitins that are important for evasion of host defenses and stimulation of the host immune system. Understanding of Pneumocystis cell signaling pathways is incomplete, but much has been deduced by comparison of the Pneumocystis genome with homologous genes and proteins in related fungi. In this mini-review, the pathobiology of Pneumocystis is reviewed, with particular focus on the life cycle, cell wall components and cell signal transduction. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Structural changes in a commercial lithium-ion battery during electrochemical cycling: An in situ neutron diffraction study

NASA Astrophysics Data System (ADS)

Sharma, Neeraj; Peterson, Vanessa K.; Elcombe, Margaret M.; Avdeev, Maxim; Studer, Andrew J.; Blagojevic, Ned; Yusoff, Rozila; Kamarulzaman, Norlida

The structural response to electrochemical cycling of the components within a commercial Li-ion battery (LiCoO 2 cathode, graphite anode) is shown through in situ neutron diffraction. Lithuim insertion and extraction is observed in both the cathode and anode. In particular, reversible Li incorporation into both layered and spinel-type LiCoO 2 phases that comprise the cathode is shown and each of these components features several phase transitions attributed to Li content and correlated with the state-of-charge of the battery. At the anode, a constant cell voltage correlates with a stable lithiated graphite phase. Transformation to de-lithiated graphite at the discharged state is characterised by a sharp decrease in both structural cell parameters and cell voltage. In the charged state, a two-phase region exists and is composed of the lithiated graphite phase and about 64% LiC 6. It is postulated that trapping Li in the solid|electrolyte interface layer results in minimal structural changes to the lithiated graphite anode across the constant cell voltage regions of the electrochemical cycle.

Emerging players in the initiation of eukaryotic DNA replication

PubMed Central

2012-01-01

Faithful duplication of the genome in eukaryotes requires ordered assembly of a multi-protein complex called the pre-replicative complex (pre-RC) prior to S phase; transition to the pre-initiation complex (pre-IC) at the beginning of DNA replication; coordinated progression of the replisome during S phase; and well-controlled regulation of replication licensing to prevent re-replication. These events are achieved by the formation of distinct protein complexes that form in a cell cycle-dependent manner. Several components of the pre-RC and pre-IC are highly conserved across all examined eukaryotic species. Many of these proteins, in addition to their bona fide roles in DNA replication are also required for other cell cycle events including heterochromatin organization, chromosome segregation and centrosome biology. As the complexity of the genome increases dramatically from yeast to human, additional proteins have been identified in higher eukaryotes that dictate replication initiation, progression and licensing. In this review, we discuss the newly discovered components and their roles in cell cycle progression. PMID:23075259

The retinoid X receptor agonist, 9-cis UAB30, inhibits cutaneous T-cell lymphoma proliferation through the SKP2-p27kip1 axis.

PubMed

Chou, Chu-Fang; Hsieh, Yu-Hua; Grubbs, Clinton J; Atigadda, Venkatram R; Mobley, James A; Dummer, Reinhard; Muccio, Donald D; Eto, Isao; Elmets, Craig A; Garvey, W Timothy; Chang, Pi-Ling

2018-06-01

Bexarotene (Targretin ® ) is currently the only FDA approved retinoid X receptor (RXR) -selective agonist for the treatment of cutaneous T-cell lymphomas (CTCLs). The main side effects of bexarotene are hypothyroidism and elevation of serum triglycerides (TGs). The novel RXR ligand, 9-cis UAB30 (UAB30) does not elevate serum TGs or induce hypothyroidism in normal subjects. To assess preclinical efficacy and mechanism of action of UAB30 in the treatment of CTCLs and compare its action with bexarotene. With patient-derived CTCL cell lines, we evaluated UAB30 function in regulating growth, apoptosis, cell cycle check points, and cell cycle-related markers. Compared to bexarotene, UAB30 had lower half maximal inhibitory concentration (IC 50 ) values and was more effective in inhibiting the G1 cell cycle checkpoint. Both rexinoids increased the stability of the cell cycle inhibitor, p27kip1 protein, in part, through targeting components involved in the ubiquitination-proteasome system: 1) decreasing SKP2, a F-box protein that binds and targets p27kip1 for degradation by 26S proteasome and 2) suppressing 20S proteasome activity (cell line-dependent) through downregulation of PSMA7, a component of the 20S proteolytic complex in 26S proteasome. UAB30 and bexarotene induce both early cell apoptosis and suppress cell proliferation. Inhibition of the G1 to S cell cycle transition by rexinoids is mediated, in part, through downregulation of SKP2 and/or 20S proteasome activity, leading to increased p27kip1 protein stability. Because UAB30 has minimal effect in elevating serum TGs and inducing hypothyroidism, it is potentially a better alternative to bexarotene for the treatment of CTCLs. Copyright © 2018 Japanese Society for Investigative Dermatology. Published by Elsevier B.V. All rights reserved.

The Interplay between Cell Wall Mechanical Properties and the Cell Cycle in Staphylococcus aureus

PubMed Central

Bailey, Richard G.; Turner, Robert D.; Mullin, Nic; Clarke, Nigel; Foster, Simon J.; Hobbs, Jamie K.

2014-01-01

The nanoscale mechanical properties of live Staphylococcus aureus cells during different phases of growth were studied by atomic force microscopy. Indentation to different depths provided access to both local cell wall mechanical properties and whole-cell properties, including a component related to cell turgor pressure. Local cell wall properties were found to change in a characteristic manner throughout the division cycle. Splitting of the cell into two daughter cells followed a local softening of the cell wall along the division circumference, with the cell wall on either side of the division circumference becoming stiffer. Once exposed, the newly formed septum was found to be stiffer than the surrounding, older cell wall. Deeper indentations, which were affected by cell turgor pressure, did not show a change in stiffness throughout the division cycle, implying that enzymatic cell wall remodeling and local variations in wall properties are responsible for the evolution of cell shape through division. PMID:25468333

Cell module and fuel conditioner development

NASA Technical Reports Server (NTRS)

Feret, J. M.

1981-01-01

A phosphoric acid fuel cell (PAFC) stack design having a 10 kW power rating for operation at higher than atmospheric pressure based on the existing Mark II design configuration is described. Functional analysis, trade studies and thermodynamic cycle analysis for requirements definition and system operating parameter selection purposes were performed. Fuel cell materials and components, and performance testing and evaluation of the repeating electrode components were characterized. The state of the art manufacturing technology for all fuel cell components and the fabrication of short stacks of various sites were established. A 10 kW PAFC stack design for higher pressure operation utilizing the top down systems engineering aproach was developed.

Achieving Precision Death with Cell-Cycle Inhibitors that Target DNA Replication and Repair.

PubMed

Lin, Aimee Bence; McNeely, Samuel C; Beckmann, Richard P

2017-07-01

All cancers are characterized by defects in the systems that ensure strict control of the cell cycle in normal tissues. The consequent excess tissue growth can be countered by drugs that halt cell division, and, indeed, the majority of chemotherapeutics developed during the last century work by disrupting processes essential for the cell cycle, particularly DNA synthesis, DNA replication, and chromatid segregation. In certain contexts, the efficacy of these classes of drugs can be impressive, but because they indiscriminately block the cell cycle of all actively dividing cells, their side effects severely constrain the dose and duration with which they can be administered, allowing both normal and malignant cells to escape complete growth arrest. Recent progress in understanding how cancers lose control of the cell cycle, coupled with comprehensive genomic profiling of human tumor biopsies, has shown that many cancers have mutations affecting various regulators and checkpoints that impinge on the core cell-cycle machinery. These defects introduce unique vulnerabilities that can be exploited by a next generation of drugs that promise improved therapeutic windows in patients whose tumors bear particular genomic aberrations, permitting increased dose intensity and efficacy. These developments, coupled with the success of new drugs targeting cell-cycle regulators, have led to a resurgence of interest in cell-cycle inhibitors. This review in particular focuses on the newer strategies that may facilitate better therapeutic targeting of drugs that inhibit the various components that safeguard the fidelity of the fundamental processes of DNA replication and repair. Clin Cancer Res; 23(13); 3232-40. ©2017 AACR . ©2017 American Association for Cancer Research.

Myeloid Leukemia Factor 1 inhibits erythropoietin-induced differentiation, cell cycle exit and p27Kip1 accumulation.

PubMed

Winteringham, Louise Natalie; Kobelke, Simon; Williams, James Howard; Ingley, Evan; Klinken, Svend Peter

2004-06-24

Myeloid leukemia factor 1 (MLF1) is a novel oncoprotein involved in translocations associated with acute myeloid leukemia (AML), especially erythroleukemias. In this study, we demonstrate that ectopic expression of Mlf1 prevented J2E erythroleukemic cells from undergoing biological and morphological maturation in response to erythropoietin (Epo). We show that Mlf1 inhibited Epo-induced cell cycle exit and suppressed a rise in the cell cycle inhibitor p27(Kip1). Unlike differentiating J2E cells, Mlf1-expressing cells did not downregulate Cul1 and Skp2, components of the ubiquitin E3 ligase complex SCF(Skp2) involved in the proteasomal degradation of p27(Kip1). In contrast, Mlf1 did not interfere with increases in p27(Kip1) and terminal differentiation initiated by thyroid hormone withdrawal from erythroid cells, or cytokine-stimulated maturation of myeloid cells. These data demonstrate that Mlf1 interferes with an Epo-responsive pathway involving p27(Kip1) accumulation, which inhibits cell cycle arrest essential for erythroid terminal differentiation.

Unexpected Voltage Fade in LMR-NMC Oxides Cycled below the “Activation” Plateau

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Yan; Bareno, Javier; Bettge, Martin

2015-01-01

A common feature of lithium-excess layered oxides, nominally of composition xLi 2MnO 3•(1-x)LiMO 2 (M = transition metal) is a high-voltage plateau (~4.5 V vs. Li/Li +) in their capacity-voltage profile during the first delithiation cycle. This plateau is believed to result from activation of the Li 2MnO 3 component, which makes additional lithium available for electrochemical cycling. However, oxides cycled beyond this activation plateau are known to display voltage fade which is a continuous reduction in their equilibrium potential. In this article we show that these oxides display gradual voltage fade even on electrochemical cycling in voltage ranges wellmore » below the activation plateau. The average fade is ~0.08 mV-cycle-1 for Li 1.2Ni 0.15Mn 0.55Co 0.1O 2 vs. Li cells after 20 cycles in the 2–4.1 V range at 55°C; a ~54 mV voltage hysteresis, expressed as the difference in average cell voltage between charge and discharge cycles, is also observed. The voltage fade results from a gradual accumulation of local spinel environments in the crystal structure. Some of these spinel sites result from lithium deficiencies during oxide synthesis and are likely to be at the particle surfaces; other sites result from the migration of transition metal atoms in the partially-delithiated LiMO 2 component into the lithium planes during electrochemical cycling. The observed rate of voltage fade depends on a combination of factors that includes the phase equilibrium between the layered and spinel components and the kinetics of transition metal migration.« less

Redistribution of cell cycle by arsenic trioxide is associated with demethylation and expression changes of cell cycle related genes in acute promyelocytic leukemia cell line (NB4).

PubMed

Hassani, Saeed; Khaleghian, Ali; Ahmadian, Shahin; Alizadeh, Shaban; Alimoghaddam, Kamran; Ghavamzadeh, Ardeshir; Ghaffari, Seyed H

2018-01-01

PML-RARα perturbs the normal epigenetic setting, which is essential to oncogenic transformation in acute promyelocytic leukemia (APL). Transcription induction and recruitment of DNA methyltransferases (DNMTs) by PML-RARα and subsequent hypermethylation are components of this perturbation. Arsenic trioxide (ATO), an important drug in APL therapy, concurrent with degradation of PML-RARα induces cell cycle change and apoptosis. How ATO causes cell cycle alteration has remained largely unexplained. Here, we investigated DNA methylation patterns of cell cycle regulatory genes promoters, the effects of ATO on the methylated genes and cell cycle distribution in an APL cell line, NB4. Analysis of promoter methylation status of 22 cell cycle related genes in NB4 revealed that CCND1, CCNE1, CCNF, CDKN1A, GADD45α, and RBL1 genes were methylated 60.7, 84.6, 58.6, 8.7, 33.4, and 73.7%, respectively, that after treatment with 2 μM ATO for 48 h, turn into 0.6, 13.8, 0.1, 6.6, 10.7, and 54.5% methylated. ATO significantly reduced the expression of DNMT1, 3A, and 3B. ATO induced the expression of CCND1, CCNE1, and GADD45α genes, suppressed the expression of CCNF and CDKN1A genes, which were consistent with decreased number of cells in G1 and S phases and increased number of cells in G2/M phase. In conclusion, demethylation and alteration in the expression level of the cell cycle related genes may be possible mechanisms in ATO-induced cell cycle arrest in APL cells. It may suggest that ATO by demethylation of CCND1 and CCNE1 and their transcriptional activation accelerates G1 and S transition into the G2/M cell cycle arrest.

Glycogen Synthase Kinase-3 and Mammalian Target of Rapamycin Pathways Contribute to DNA Synthesis, Cell Cycle Progression, and Proliferation in Human Islets

PubMed Central

Liu, Hui; Remedi, Maria S.; Pappan, Kirk L.; Kwon, Guim; Rohatgi, Nidhi; Marshall, Connie A.; McDaniel, Michael L.

2009-01-01

OBJECTIVE—Our previous studies demonstrated that nutrient regulation of mammalian target of rapamycin (mTOR) signaling promotes regenerative processes in rodent islets but rarely in human islets. Our objective was to extend these findings by using therapeutic agents to determine whether the regulation of glycogen synthase kinase-3 (GSK-3)/β-catenin and mTOR signaling represent key components necessary for effecting a positive impact on human β-cell mass relevant to type 1 and 2 diabetes. RESEARCH DESIGN AND METHODS—Primary adult human and rat islets were treated with the GSK-3 inhibitors, LiCl and the highly potent 1-azakenpaullone (1-Akp), and with nutrients. DNA synthesis, cell cycle progression, and proliferation of β-cells were assessed. Measurement of insulin secretion and content and Western blot analysis of GSK-3 and mTOR signaling components were performed. RESULTS—Human islets treated for 4 days with LiCl or 1-Akp exhibited significant increases in DNA synthesis, cell cycle progression, and proliferation of β-cells that displayed varying degrees of sensitivity to rapamycin. Intermediate glucose (8 mmol/l) produced a striking degree of synergism in combination with GSK-3 inhibition to enhance bromodeoxyuridine (BrdU) incorporation and Ki-67 expression in human β-cells. Nuclear translocation of β-catenin responsible for cell proliferation was found to be particularly sensitive to rapamycin. CONCLUSIONS—A combination of GSK-3 inhibition and nutrient activation of mTOR contributes to enhanced DNA synthesis, cell cycle progression, and proliferation of human β-cells. Identification of therapeutic agents that appropriately regulate GSK-3 and mTOR signaling may provide a feasible and available approach to enhance human islet growth and proliferation. PMID:19073772

Experiments and Cycling at the LHC Prototype Half-Cell

NASA Astrophysics Data System (ADS)

Saban, R.; Casas-Cubillos, J.; Coull, L.; Cruikshank, P.; Dahlerup-Petersen, K.; Hilbert, B.; Krainz, G.; Kos, N.; Lebrun, P.; Momal, F.; Misiaen, D.; Parma, V.; Poncet, A.; Riddone, G.; Rijllart, A.; Rodriguez-Mateos, F.; Schmidt, R.; Serio, L.; Wallen, E.; van Weelderen, R.; Williams, L. R.

1997-05-01

The first version of the LHC prototype half-cell has been in operation since February 1995. It consists of one quadrupole and three 10-m twin aperture dipole magnets which operate at 1.8 K. This experimental set-up has been used to observe and study phenomena which appear when the systems are assembled in one unit and influence one another. The 18-month long experimental program has validated the cryogenic system and yielded a number of results on cryogenic instrumentation, magnet protection and vacuum in particular under non-standard operating conditions. The program was recently complemented by the cycling experiment: it consisted in powering the magnets following the ramp rates which will be experienced by the magnets during an LHC injection. In order to simulate 10 years of routine operation of LHC, more than 2000 1-hour cycles were performed interleaved with provoked quenches. The objective of this experiment was to reveal eventual flaws in the design of components. The prototype half-cell performed to expectations showing no sign of failure of fatigue of components for more than 2000 cycles until one of the dipoles started exhibiting an erratic quench behavior.

Cell Cycle Synchronization of HeLa Cells to Assay EGFR Pathway Activation.

PubMed

Wee, Ping; Wang, Zhixiang

2017-01-01

Progression through the cell cycle causes changes in the cell's signaling pathways that can alter EGFR signal transduction. Here, we describe drug-derived protocols to synchronize HeLa cells in various phases of the cell cycle, including G1 phase, S phase, G2 phase, and mitosis, specifically in the mitotic stages of prometaphase, metaphase, and anaphase/telophase. The synchronization procedures are designed to allow synchronized cells to be treated for EGF and collected for the purpose of Western blotting for EGFR signal transduction components.S phase synchronization is performed by thymidine block, G2 phase with roscovitine, prometaphase with nocodazole, metaphase with MG132, and anaphase/telophase with blebbistatin. G1 phase synchronization is performed by culturing synchronized mitotic cells obtained by mitotic shake-off. We also provide methods to validate the synchronization methods. For validation by Western blotting, we provide the temporal expression of various cell cycle markers that are used to check the quality of the synchronization. For validation of mitotic synchronization by microscopy, we provide a guide that describes the physical properties of each mitotic stage, using their cellular morphology and DNA appearance. For validation by flow cytometry, we describe the use of imaging flow cytometry to distinguish between the phases of the cell cycle, including between each stage of mitosis.

PARP-3 localizes preferentially to the daughter centriole and interferes with the G1/S cell cycle progression.

PubMed

Augustin, Angélique; Spenlehauer, Catherine; Dumond, Hélène; Ménissier-De Murcia, Josiane; Piel, Matthieu; Schmit, Anne-Catherine; Apiou, Françoise; Vonesch, Jean-Luc; Kock, Michael; Bornens, Michel; De Murcia, Gilbert

2003-04-15

A novel member of the poly(ADP-ribose) polymerase (PARP) family, hPARP-3, is identified here as a core component of the centrosome. hPARP-3 is preferentially localized to the daughter centriole throughout the cell cycle. The N-terminal domain (54 amino acids) of hPARP-3 is responsible for its centrosomal localization. Full-length hPAPR-3 (540 amino acids, with an apparent mass of 67 kDa) synthesizes ADP-ribose polymers during its automodification. Overexpression of hPARP-3 or its N-terminal domain does not influence centrosomal duplication or amplification but interferes with the G1/S cell cycle progression. PARP-1 also resides for part of the cell cycle in the centrosome and interacts with hPARP-3. The presence of both PARP-1 and PARP-3 at the centrosome may link the DNA damage surveillance network to the mitotic fidelity checkpoint.

Chk1 and Cds1: linchpins of the DNA damage and replication checkpoint pathways

PubMed Central

Rhind, Nicholas; Russell, Paul

2010-01-01

SUMMARY Recent work on the mechanisms of DNA damage and replication cell cycle checkpoints has revealed great similarity between the checkpoint pathways of organisms as diverse as yeasts, flies and humans. However, there are differences in the ways these organisms regulate their cell cycles. To connect the conserved checkpoint pathways with various cell cycle targets requires an adaptable link that can target different cell cycle components in different organisms. The Chk1 and Cds1 protein kinases, downstream effectors in the checkpoint pathways, seem to play just such roles. Perhaps more surprisingly, the two kinases not only have different targets in different organisms but also seem to respond to different signals in different organisms. So, whereas in fission yeast Chk1 is required for the DNA damage checkpoint and Cds1 is specifically involved in the replication checkpoint, their roles seem to be shuffled in metazoans. PMID:11058076

SPARC expression induces cell cycle arrest via STAT3 signaling pathway in medulloblastoma cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chetty, Chandramu; Dontula, Ranadheer; Ganji, Purnachandra Nagaraju

2012-01-13

Highlights: Black-Right-Pointing-Pointer Ectopic expression of SPARC impaired cell proliferation in medulloblastoma cells. Black-Right-Pointing-Pointer SPARC expression induces STAT3 mediated cell cycle arrest in medulloblastoma cells. Black-Right-Pointing-Pointer SPARC expression significantly inhibited pre-established tumor growth in nude-mice. -- Abstract: Dynamic cell interaction with ECM components has profound influence in cancer progression. SPARC is a component of the ECM, impairs the proliferation of different cell types and modulates tumor cell aggressive features. We previously reported that SPARC expression significantly impairs medulloblastoma tumor growth in vivo. In this study, we demonstrate that expression of SPARC inhibits medulloblastoma cell proliferation. MTT assay indicated a dose-dependent reductionmore » in tumor cell proliferation in adenoviral mediated expression of SPARC full length cDNA (Ad-DsRed-SP) in D425 and UW228 cells. Flow cytometric analysis showed that Ad-DsRed-SP-infected cells accumulate in the G2/M phase of cell cycle. Further, immunoblot and immunoprecipitation analyses revealed that SPARC induced G2/M cell cycle arrest was mediated through inhibition of the Cyclin-B-regulated signaling pathway involving p21 and Cdc2 expression. Additionally, expression of SPARC decreased STAT3 phosphorylation at Tyr-705; constitutively active STAT3 expression reversed SPARC induced G2/M arrest. Ad-DsRed-SP significantly inhibited the pre-established orthotopic tumor growth and tumor volume in nude-mice. Immunohistochemical analysis of tumor sections from mice treated with Ad-DsRed-SP showed decreased immunoreactivity for pSTAT3 and increased immunoreactivity for p21 compared to tumor section from mice treated with mock and Ad-DsRed. Taken together our studies further reveal that STAT3 plays a key role in SPARC induced G2/M arrest in medulloblastoma cells. These new findings provide a molecular basis for the mechanistic understanding of the effects of SPARC on medulloblastoma tumor cell proliferation.« less

Component variations and their effects on bipolar nickel-hydrogen cell performance

NASA Technical Reports Server (NTRS)

Manzo, Michelle A.; Gahn, Randall F.; Gonzalez-Sanabria, Olga D.; Cataldo, Robert L.; Gemeiner, Russel P.

1987-01-01

A 50 cell bipolar nickel-hydrogen battery was assembled to demonstrate the feasibility of constructing a high voltage stack of cells. Various component combinations were tested in this battery. The battery had approximately 1 ampere-hour of capacity and was constructed from components with an active area of 2 x 2 inches. The components were parametrically varied to give a comparison of nickel electrodes, hydrogen electrodes, separators, fill procedures and electrolyte reservoir plate thicknesses. Groups of five cells were constructed using the same components; ten combinations were tested in all. The battery was thoroughly characterized at various change and discharge rates as well as with various pulse patterns and rates. Over a period of 1400 40-percent DOD LEO cycles some of the groups began to exhibit performance differences. In general, only separator variations had a significant effect on cell performance. It also appears that shunt currents may have been operating within the stack, resulting in electrolyte transfer from one cell to another, thus contributing to cell performance variations.

Component variations and their effects on bipolar nickel-hydrogen cell performance

NASA Technical Reports Server (NTRS)

Manzo, Michelle A.; Gahn, Randall F.; Gonzalez-Sanabria, Olga D.; Cataldo, Robert L.; Gemeiner, Russel P.

1987-01-01

A 50 cell bipolar nickel-hydrogen battery was assembled to demonstrate the feasibility of constructing a high voltage stack of cells. Various component combinations were tested in this battery. The battery had approximately 1 ampere-hour of capacity and was constructed from components with an active area of 2" X 2". The components were parametrically varied to give a comparison of nickel electrodes, hydrogen electrodes, separators, fill procedures and electrolyte reservoir plate thicknesses. Groups of five cells were constructed using the same components; ten combinations were tested in all. The battery was thoroughly characterized at various change and discharge rates as well as with various pulse patterns and rates. Over a period of 1400 40% DOD LEO cycles some of the groups began to exhibit performance differences. In general, only separator variations had a significant effect on cell performance. It also appears that shunt currents may have been operating within the stack, resulting in electrolyte transfer from one cell to another, thus contributing to cell performance variations.

The DREAM complex through its subunit Lin37 cooperates with Rb to initiate quiescence

PubMed Central

Mages, Christina FS; Wintsche, Axel; Bernhart, Stephan H

2017-01-01

The retinoblastoma Rb protein is an important factor controlling the cell cycle. Yet, mammalian cells carrying Rb deletions are still able to arrest under growth-limiting conditions. The Rb-related proteins p107 and p130, which are components of the DREAM complex, had been suggested to be responsible for a continued ability to arrest by inhibiting E2f activity and by recruiting chromatin-modifying enzymes. Here, we show that p130 and p107 are not sufficient for DREAM-dependent repression. We identify the MuvB protein Lin37 as an essential factor for DREAM function. Cells not expressing Lin37 proliferate normally, but DREAM completely loses its ability to repress genes in G0/G1 while all remaining subunits, including p130/p107, still bind to target gene promoters. Furthermore, cells lacking both Rb and Lin37 are incapable of exiting the cell cycle. Thus, Lin37 is an essential component of DREAM that cooperates with Rb to induce quiescence. PMID:28920576

Interaction of FeS 2 and Sulfur in Li-S Battery System

DOE PAGES

Sun, Ke; Cama, Christina A.; DeMayo, Rachel A.; ...

2016-09-09

Many transition metal sulfides are electronically conductive, electrochemically active and reversible in reactions with lithium. However, the application of transition metal sulfides as sulfur cathode additives in lithium-sulfur (Li-S) batteries has not been fully explored. In this study, Pyrite (FeS 2) is studied as a capacity contributing conductive additive in sulfur cathode for Li-S batteries. Electrochemically discharging the S-FeS 2 composite electrodes to 1.0 V activates the FeS 2 component, contributing to the improved Li-S cell discharge energy density. However, direct activation of the FeS 2 component in a fresh S-FeS 2 cell results in a significant shuttling effect inmore » the subsequent charging process, preventing further cell cycling. The slight FeS 2 solubility in electrolyte and its activation alone in S-FeS 2 cells are not the root causes of the severe shuttling effect. The observed severe shuttling effect is strongly correlated to the 1st charging of the activated S-FeS 2 electrode that promotes iron dissolution in electrolyte and the deposition of electronically conductive FeS on the anode SEI. Pre-cycling of the S-FeS 2 cell prior to the FeS 2 activation or the use of LiNO 3 electrolyte additive help to prevent the severe shuttling effect and allow the cell to cycle between 2.6 V to 1.0 V with an extra capacity contribution from the FeS2 components. However, a more effective method of anode pre-passivation is still needed to fully protect the lithium surface from FeS deposition and allow the S-FeS 2 electrode to maintain high energy density over extended cycles. A mechanism explaining the observed phenomena based on the experimental data is proposed and discussed« less

The Formation of Tight Tumor Clusters Affects the Efficacy of Cell Cycle Inhibitors: A Hybrid Model Study

PubMed Central

Kim, MunJu; Reed, Damon; Rejniak, Katarzyna A.

2014-01-01

Cyclin-dependent kinases (CDKs) are vital in regulating cell cycle progression, and, thus, in highly proliferating tumor cells CDK inhibitors are gaining interest as potential anticancer agents. Clonogenic assay experiments are frequently used to determine drug efficacy against the survival and proliferation of cancer cells. While the anticancer mechanisms of drugs are usually described at the intracellular single-cell level, the experimental measurements are sampled from the entire cancer cell population. This approach may lead to discrepancies between the experimental observations and theoretical explanations of anticipated drug mechanisms. To determine how individual cell responses to drugs that inhibit CDKs affect the growth of cancer cell populations, we developed a spatially explicit hybrid agent-based model. In this model, each cell is equipped with internal cell cycle regulation mechanisms, but it is also able to interact physically with its neighbors. We model cell cycle progression, focusing on the G1 and G2/M cell cycle checkpoints, as well as on related essential components, such as CDK1, CDK2, cell size, and DNA damage. We present detailed studies of how the emergent properties (e.g., cluster formation) of an entire cell population depend on altered physical and physiological parameters. We analyze the effects of CDK1 and CKD2 inhibitors on population growth, time-dependent changes in cell cycle distributions, and the dynamic evolution of spatial cell patterns. We show that cell cycle inhibitors that cause cell arrest at different cell cycle phases are not necessarily synergistically super-additive. Finally, we demonstrate that the physical aspects of cell population growth, such as the formation of tight cell clusters versus dispersed colonies, alter the efficacy of cell cycle inhibitors, both in 2D and 3D simulations. This finding may have implications for interpreting the treatment efficacy results of in vitro experiments, in which treatment is applied before the cells can grow to produce clusters, especially because in vivo tumors, in contrast, form large masses before they are detected and treated. PMID:24607745

Measuring cell cycle progression kinetics with metabolic labeling and flow cytometry.

PubMed

Fleisig, Helen; Wong, Judy

2012-05-22

Precise control of the initiation and subsequent progression through the various phases of the cell cycle are of paramount importance in proliferating cells. Cell cycle division is an integral part of growth and reproduction and deregulation of key cell cycle components have been implicated in the precipitating events of carcinogenesis. Molecular agents in anti-cancer therapies frequently target biological pathways responsible for the regulation and coordination of cell cycle division. Although cell cycle kinetics tend to vary according to cell type, the distribution of cells amongst the four stages of the cell cycle is rather consistent within a particular cell line due to the consistent pattern of mitogen and growth factor expression. Genotoxic events and other cellular stressors can result in a temporary block of cell cycle progression, resulting in arrest or a temporary pause in a particular cell cycle phase to allow for instigation of the appropriate response mechanism. The ability to experimentally observe the behavior of a cell population with reference to their cell cycle progression stage is an important advance in cell biology. Common procedures such as mitotic shake off, differential centrifugation or flow cytometry-based sorting are used to isolate cells at specific stages of the cell cycle. These fractionated, cell cycle phase-enriched populations are then subjected to experimental treatments. Yield, purity and viability of the separated fractions can often be compromised using these physical separation methods. As well, the time lapse between separation of the cell populations and the start of experimental treatment, whereby the fractionated cells can progress from the selected cell cycle stage, can pose significant challenges in the successful implementation and interpretation of these experiments. Other approaches to study cell cycle stages include the use of chemicals to synchronize cells. Treatment of cells with chemical inhibitors of key metabolic processes for each cell cycle stage are useful in blocking the progression of the cell cycle to the next stage. For example, the ribonucleotide reductase inhibitor hydroxyurea halts cells at the G1/S juncture by limiting the supply of deoxynucleotides, the building blocks of DNA. Other notable chemicals include treatment with aphidicolin, a polymerase alpha inhibitor for G1 arrest, treatment with colchicine and nocodazole, both of which interfere with mitotic spindle formation to halt cells in M phase and finally, treatment with the DNA chain terminator 5-fluorodeoxyridine to initiate S phase arrest. Treatment with these chemicals is an effective means of synchronizing an entire population of cells at a particular phase. With removal of the chemical, cells rejoin the cell cycle in unison. Treatment of the test agent following release from the cell cycle blocking chemical ensures that the drug response elicited is from a uniform, cell cycle stage-specific population. However, since many of the chemical synchronizers are known genotoxic compounds, teasing apart the participation of various response pathways (to the synchronizers vs. the test agents) is challenging. Here we describe a metabolic labeling method for following a subpopulation of actively cycling cells through their progression from the DNA replication phase, through to the division and separation of their daughter cells. Coupled with flow cytometry quantification, this protocol enables for measurement of kinetic progression of the cell cycle in the absence of either mechanically- or chemically- induced cellular stresses commonly associated with other cell cycle synchronization methodologies. In the following sections we will discuss the methodology, as well as some of its applications in biomedical research.

Cyclin D1-Cdk4 controls glucose metabolism independently of cell cycle progression.

PubMed

Lee, Yoonjin; Dominy, John E; Choi, Yoon Jong; Jurczak, Michael; Tolliday, Nicola; Camporez, Joao Paulo; Chim, Helen; Lim, Ji-Hong; Ruan, Hai-Bin; Yang, Xiaoyong; Vazquez, Francisca; Sicinski, Piotr; Shulman, Gerald I; Puigserver, Pere

2014-06-26

Insulin constitutes a principal evolutionarily conserved hormonal axis for maintaining glucose homeostasis; dysregulation of this axis causes diabetes. PGC-1α (peroxisome-proliferator-activated receptor-γ coactivator-1α) links insulin signalling to the expression of glucose and lipid metabolic genes. The histone acetyltransferase GCN5 (general control non-repressed protein 5) acetylates PGC-1α and suppresses its transcriptional activity, whereas sirtuin 1 deacetylates and activates PGC-1α. Although insulin is a mitogenic signal in proliferative cells, whether components of the cell cycle machinery contribute to its metabolic action is poorly understood. Here we report that in mice insulin activates cyclin D1-cyclin-dependent kinase 4 (Cdk4), which, in turn, increases GCN5 acetyltransferase activity and suppresses hepatic glucose production independently of cell cycle progression. Through a cell-based high-throughput chemical screen, we identify a Cdk4 inhibitor that potently decreases PGC-1α acetylation. Insulin/GSK-3β (glycogen synthase kinase 3-beta) signalling induces cyclin D1 protein stability by sequestering cyclin D1 in the nucleus. In parallel, dietary amino acids increase hepatic cyclin D1 messenger RNA transcripts. Activated cyclin D1-Cdk4 kinase phosphorylates and activates GCN5, which then acetylates and inhibits PGC-1α activity on gluconeogenic genes. Loss of hepatic cyclin D1 results in increased gluconeogenesis and hyperglycaemia. In diabetic models, cyclin D1-Cdk4 is chronically elevated and refractory to fasting/feeding transitions; nevertheless further activation of this kinase normalizes glycaemia. Our findings show that insulin uses components of the cell cycle machinery in post-mitotic cells to control glucose homeostasis independently of cell division.

Molecular Biology of Prune Dwarf Virus—A Lesser Known Member of the Bromoviridae but a Vital Component in the Dynamic Virus–Host Cell Interaction Network

PubMed Central

Bujarski, Józef J.

2017-01-01

Prune dwarf virus (PDV) is one of the members of Bromoviridae family, genus Ilarvirus. Host components that participate in the regulation of viral replication or cell-to-cell movement via plasmodesmata are still unknown. In contrast, viral infections caused by some other Bromoviridae members are well characterized. Bromoviridae can be distinguished based on localization of their replication process in infected cells, cell-to-cell movement mechanisms, and plant-specific response reactions. Depending upon the genus, “genome activation” and viral replication are linked to various membranous structures ranging from endoplasmic reticulum, to tonoplast. In the case of PDV, there is still no evidence of natural resistance sources in the host plants susceptible to virus infection. Apparently, PDV has a great ability to overcome the natural defense responses in a wide spectrum of plant hosts. The first manifestations of PDV infection are specific cell membrane alterations, and the formation of replicase complexes that support PDV RNA replication inside the spherules. During each stage of its life cycle, the virus uses cell components to replicate and to spread in whole plants, within the largely suppressed cellular immunity environment. This work presents the above stages of the PDV life cycle in the context of current knowledge about other Bromoviridae members. PMID:29258199

Cell wall mannoprotein of Candida albicans induces cell cycle alternation and inhibits apoptosis of HaCaT cells via NF-κB signal pathway.

PubMed

Han, Yang; Jiang, Hang-Hang; Zhang, Yu-Jing; Hao, Xing-Jia; Sun, Yu-Zhe; Qi, Rui-Qun; Chen, Hong-Duo; Gao, Xing-Hua

2017-10-01

Candida albicans (C. albicans) is a commensal organism in human and a well-known dimorphic opportunistic pathogenic fungus. Though plenty of researches on the pathogenesis of C. albicans have been performed, the mechanism is not fully understood. The cell wall components of C. albicans have been documented to play important roles in its pathogenic processes. To further study the infectious mechanism of C. albicans, we investigated the potential functional role of its cell wall mannoprotein in cell cycle and apoptosis of HaCaT cells. We found that mannoprotein could promote the transition of cell cycle from G1/G0 to S phase, in which Cyclin D1, CDK4 and p-Rb, the major regulators of the cell cycle progression, showed significant upregulation, and CDKN1A (cyclin dependent kinase inhibitor 1A (p21)) showed significant downregulation. Mannoprotein also could inhibit apoptosis of HaCaT cells, which was well associated with increased expression of BCL2 (Bcl-2). Moreover, mannoprotein could increase the phosphorylation levels of RELA (p65) and NFKBIA (IκBα), as the key factors of NF-κB signal pathway in HaCaT cells, suggesting the activation of NF-κB signal pathway. Additionally, a NF-κB specific inhibitor, PDTC, could rescue the effect of mannoprotein on cell cycle and apoptosis of HaCaT cells, which suggested that mannoprotein could activate NF-κB signal pathway to mediate cell cycle alternation and inhibit apoptosis. Copyright © 2017. Published by Elsevier Ltd.

Ramgen Power Systems-Supersonic Component Technology for Military Engine Applications

DTIC Science & Technology

2006-11-01

turbine efficiency power (kW) LHV efficiency HHV efficiency notes **Current Design Point 0.45 1700 1013 84.4% 220.1 35.4% 31.8% - Rampressor...tor (such as a standalone power-only mode device), or to a fuel cell in a hybrid configuration. This paper presents the development of the RPS gas...turbine technology and potential applications to the two specific engine cycle configurations, i.e., an indirect fuel cell / RPS turbine hybrid-cycle

Cdc6 localizes to S- and G2-phase centrosomes in a cell cycle-dependent manner

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Gwang Su; Kang, Jeeheon; Bang, Sung Woong

2015-01-16

Highlights: • Cdc6 protein is a component of the pre-replicative complex required for chromosomal replication initiation. • Cdc6 localized to centrosomes of S and G2 phases in a cell cycle-dependent manner. • The centrosomal localization was governed by centrosomal localization signal sequences of Cdc6. • Deletions or substitution mutations on the centrosomal localization signal interfered with centrosomal localization of the Cdc6 proteins. - Abstract: The Cdc6 protein has been primarily investigated as a component of the pre-replicative complex for the initiation of chromosome replication, which contributes to maintenance of chromosomal integrity. Here, we show that Cdc6 localized to the centrosomesmore » during S and G2 phases of the cell cycle. The centrosomal localization was mediated by Cdc6 amino acid residues 311–366, which are conserved within other Cdc6 homologues and contains a putative nuclear export signal. Deletions or substitutions of the amino acid residues did not allow the proteins to localize to centrosomes. In contrast, DsRed tag fused to the amino acid residues localized to centrosomes. These results indicated that a centrosome localization signal is contained within amino acid residues 311–366. The cell cycle-dependent centrosomal localization of Cdc6 in S and G2 phases suggest a novel function of Cdc6 in centrosomes.« less

Expression of progesterone receptor membrane component-2 within the immature rat ovary and its role in regulating mitosis and apoptosis of spontaneously immortalized granulosa cells.

PubMed

Griffin, Daniel; Liu, Xiufang; Pru, Cindy; Pru, James K; Peluso, John J

2014-08-01

Progesterone receptor membrane component 2 (Pgrmc2) mRNA was detected in the immature rat ovary. By 48 h after eCG, Pgrmc2 mRNA levels decreased by 40% and were maintained at 48 h post-hCG. Immunohistochemical studies detected PGRMC2 in oocytes and ovarian surface epithelial, interstitial, thecal, granulosa, and luteal cells. PGRMC2 was also present in spontaneously immortalized granulosa cells, localizing to the cytoplasm of interphase cells and apparently to the mitotic spindle of cells in metaphase. Interestingly, PGRMC2 levels appeared to decrease during the G1 stage of the cell cycle. Moreover, overexpression of PGRMC2 suppressed entry into the cell cycle, possibly by binding the p58 form of cyclin dependent kinase 11b. Conversely, Pgrmc2 small interfering RNA (siRNA) treatment increased the percentage of cells in G1 and M stage but did not increase the number of cells, which was likely due to an increase in apoptosis. Depleting PGRMC2 did not inhibit cellular (3)H-progesterone binding, but attenuated the ability of progesterone to suppress mitosis and apoptosis. Taken together these studies suggest that PGRMC2 affects granulosa cell mitosis by acting at two specific stages of the cell cycle. First, PGRMC2 regulates the progression from the G0 into the G1 stage of the cell cycle. Second, PGRMC2 appears to localize to the mitotic spindle, where it likely promotes the final stages of mitosis. Finally, siRNA knockdown studies indicate that PGRMC2 is required for progesterone to slow the rate of granulosa cell mitosis and apoptosis. These findings support a role for PGRMC2 in ovarian follicle development. © 2014 by the Society for the Study of Reproduction, Inc.

ULTRASTRUCTURE OF THE NUCLEOLUS DURING THE CHINESE HAMSTER CELL CYCLE

PubMed Central

Noel, J. S.; Dewey, W. C.; Abel, J. H.; Thompson, R. P.

1971-01-01

Changes in the structure of the nucleolus during the cell cycle of the Chinese hamster cell in vitro were studied. Quantitative electron microscopic techniques were used to establish the size and volume changes in nucleolar structures. In mitosis, nucleolar remnants, "persistent nucleoli," consisting predominantly of ribosome-like granular material, and a granular coating on the chromosomes were observed. Persistent nucleoli were also observed in some daughter nuclei as they were leaving telophase and entering G1. During very early G1, a dense, fibrous material characteristic of interphase nucleoli was noted in the nucleoplasm of the cells. As the cells progressed through G1, a granular component appeared which was intimately associated with the fibrous material. By the middle of G1, complete, mature nucleoli were present. The nucleolar volume enlarged by a factor of two from the beginning of G1 to the middle of S primarily due to the accumulation of the granular component. During the G2 period, there was a dissolution or breakdown of the nucleolus prior to the entry of the cells into mitosis. Correlations between the quantitative aspects of this study and biochemical and cytochemical data available in the literature suggest the following: nucleolar reformation following division results from the activation of the nucleolar organizer regions which transcribe for RNA first appearing in association with protein as a fibrous component (45S RNA) and then later as a granular component (28S and 32S RNA). PMID:4933472

CSN5/JAB1 Interacts with the Centromeric Components CENP-T and CENP-W and Regulates Their Proteasome-mediated Degradation*

PubMed Central

Chun, Younghwa; Lee, Miae; Park, Byoungwoo; Lee, Soojin

2013-01-01

The CENP-T·CENP-W complex is a recently identified inner centromere component that plays crucial roles in the formation of a functional kinetochore involved in cell division during mitosis. Using yeast two-hybrid screening, we identified an interaction between CENP-T and CSN5, the fifth component of the COP9 signalosome and a key modulator of the cell cycle and cancer. Co-immunoprecipitation revealed that CSN5 directly interacts with both CENP-T and CENP-W. Ectopically expressed CSN5 promoted the ubiquitin- and proteasome-dependent degradation of CENP-T·CENP-W. The formation of a CENP-T·CENP-W complex greatly enhanced the stabilities of the respective proteins, possibly by blocking CSN5-mediated degradation. Furthermore, dysregulation of CSN5 induced severe defects in the recruitment of CENP-T·CENP-W to the kinetochore during the prophase stage of mitosis. Thus, our results indicate that CSN5 regulates the stability of the inner kinetochore components CENP-T and CENP-W, providing the first direct link between CSN5 and the mitotic apparatus, highlighting the role of CSN5 as a multifunctional cell cycle regulator. PMID:23926101

Molecular coordination of Staphylococcus aureus cell division

PubMed Central

Cotterell, Bryony E; Walther, Christa G; Fenn, Samuel J; Grein, Fabian; Wollman, Adam JM; Leake, Mark C; Olivier, Nicolas; Cadby, Ashley; Mesnage, Stéphane; Jones, Simon

2018-01-01

The bacterial cell wall is essential for viability, but despite its ability to withstand internal turgor must remain dynamic to permit growth and division. Peptidoglycan is the major cell wall structural polymer, whose synthesis requires multiple interacting components. The human pathogen Staphylococcus aureus is a prolate spheroid that divides in three orthogonal planes. Here, we have integrated cellular morphology during division with molecular level resolution imaging of peptidoglycan synthesis and the components responsible. Synthesis occurs across the developing septal surface in a diffuse pattern, a necessity of the observed septal geometry, that is matched by variegated division component distribution. Synthesis continues after septal annulus completion, where the core division component FtsZ remains. The novel molecular level information requires re-evaluation of the growth and division processes leading to a new conceptual model, whereby the cell cycle is expedited by a set of functionally connected but not regularly distributed components. PMID:29465397

Midkine-A functions upstream of Id2a to regulate cell cycle kinetics in the developing vertebrate retina

PubMed Central

2012-01-01

Background Midkine is a small heparin binding growth factor expressed in numerous tissues during development. The unique midkine gene in mammals has two paralogs in zebrafish: midkine-a (mdka) and midkine-b (mdkb). In the zebrafish retina, during both larval development and adult photoreceptor regeneration, mdka is expressed in retinal stem and progenitor cells and functions as a molecular component of the retina’s stem cell niche. In this study, loss-of-function and conditional overexpression were used to investigate the function of Mdka in the retina of the embryonic zebrafish. Results The results show that during early retinal development Mdka functions to regulate cell cycle kinetics. Following targeted knockdown of Mdka synthesis, retinal progenitors cycle more slowly, and this results in microphthalmia, a diminished rate of cell cycle exit and a temporal delay of cell cycle exit and neuronal differentiation. In contrast, Mdka overexpression results in acceleration of the cell cycle and retinal overgrowth. Mdka gain-of-function, however, does not temporally advance cell cycle exit. Experiments to identify a potential Mdka signaling pathway show that Mdka functions upstream of the HLH regulatory protein, Id2a. Gene expression analysis shows Mdka regulates id2a expression, and co-injection of Mdka morpholinos and id2a mRNA rescues the Mdka loss-of-function phenotype. Conclusions These data show that in zebrafish, Mdka resides in a shared Id2a pathway to regulate cell cycle kinetics in retinal progenitors. This is the first study to demonstrate the function of Midkine during retinal development and adds Midkine to the list of growth factors that transcriptionally regulate Id proteins. PMID:23111152

Midkine-A functions upstream of Id2a to regulate cell cycle kinetics in the developing vertebrate retina.

PubMed

Luo, Jing; Uribe, Rosa A; Hayton, Sarah; Calinescu, Anda-Alexandra; Gross, Jeffrey M; Hitchcock, Peter F

2012-10-30

Midkine is a small heparin binding growth factor expressed in numerous tissues during development. The unique midkine gene in mammals has two paralogs in zebrafish: midkine-a (mdka) and midkine-b (mdkb). In the zebrafish retina, during both larval development and adult photoreceptor regeneration, mdka is expressed in retinal stem and progenitor cells and functions as a molecular component of the retina's stem cell niche. In this study, loss-of-function and conditional overexpression were used to investigate the function of Mdka in the retina of the embryonic zebrafish. The results show that during early retinal development Mdka functions to regulate cell cycle kinetics. Following targeted knockdown of Mdka synthesis, retinal progenitors cycle more slowly, and this results in microphthalmia, a diminished rate of cell cycle exit and a temporal delay of cell cycle exit and neuronal differentiation. In contrast, Mdka overexpression results in acceleration of the cell cycle and retinal overgrowth. Mdka gain-of-function, however, does not temporally advance cell cycle exit. Experiments to identify a potential Mdka signaling pathway show that Mdka functions upstream of the HLH regulatory protein, Id2a. Gene expression analysis shows Mdka regulates id2a expression, and co-injection of Mdka morpholinos and id2a mRNA rescues the Mdka loss-of-function phenotype. These data show that in zebrafish, Mdka resides in a shared Id2a pathway to regulate cell cycle kinetics in retinal progenitors. This is the first study to demonstrate the function of Midkine during retinal development and adds Midkine to the list of growth factors that transcriptionally regulate Id proteins.

In vitro biocompatibility and proliferative effects of polar and non-polar extracts of cucurbita ficifolia on human mesenchymal stem cells.

PubMed

Aristatile, Balakrishnan; Alshammari, Ghedeir M

2017-05-01

Cucurbita ficifolia (C. ficifolia) has been traditionally known for its medicinal properties as an antioxidant, anti-diabetic and anti-inflammatory agent. However, there has been an enduring attention towards the identification of unique method, to isolate the natural components for therapeutic applications. Our study focuses on different polar and non-polar solvents (methanol, hexane and chloroform) to extract the bioactive components from C. ficifolia (pumpkin) and to study the biocompatibility and cytotoxicity effects on human bone marrow-mesenchymal stem cells (hBM-MSCs). The extracts were screened for their effects on cytotoxicity, cell proliferation and cell cycle on the hBM-MSCs cell line. The assays demonstrated that the chloroform extract was highly biocompatible, with less cytotoxic effect, and enhanced the cell proliferation. The methanol extract did not exhibit significant cytotoxicity when compare to the control. Concordantly, the cell cycle analysis confirmed that chloroform extract enhances the proliferation at lower concentrations. On the other hand, hexane extract showed high level of cytotoxicity with apoptotic and necrotic changes in hBM-MSCs. Collectively, our data revealed that chloroform is a good candidate to extract the bioactive components from C. ficifolia. Furthermore, our results suggest that specific gravity and density of the solvent might play a crucial role in the extraction process, which warrants further investigations. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Thymoquinone, a bioactive component of Nigella sativa, normalizes insulin secretion from pancreatic β-cells under glucose overload via regulation of malonyl-CoA

PubMed Central

Gray, Joshua P.; Zayasbazan Burgos, Delaine; Yuan, Tao; Seeram, Navindra; Rebar, Rebecca; Follmer, Rebecca

2015-01-01

Thymoquinone (2-isopropyl-5-methylbenzo-1,4-quinone) is a major bioactive component of Nigella sativa, a plant used in traditional medicine to treat a variety of symptoms, including elevated blood glucose levels in type 2 diabetic patients. Normalization of elevated blood glucose depends on both glucose disposal by peripheral tissues and glucose-stimulated insulin secretion (GSIS) from pancreatic β-cells. We employed clonal β-cells and rodent islets to investigate the effects of thymoquinone (TQ) and Nigella sativa extracts (NSEs) on GSIS and cataplerotic metabolic pathways implicated in the regulation of GSIS. TQ and NSE regulated NAD(P)H/NAD(P)+ ratios via a quinone-dependent redox cycling mechanism. TQ content was positively correlated with the degree of redox cycling activity of NSE extracts, suggesting that TQ is a major component engaged in mediating NSE-dependent redox cycling. Both acute and chronic exposure to TQ and NSE enhanced GSIS and were associated with the ability of TQ and NSE to increase the ATP/ADP ratio. Furthermore, TQ ameliorated the impairment of GSIS following chronic exposure of β-cells to glucose overload. This protective action was associated with the TQ-dependent normalization of chronic accumulation of malonyl-CoA, elevation of acetyl-CoA carboxylase (ACC), fatty acid synthase, and fatty acid-binding proteins following chronic glucose overload. Together, these data suggest that TQ modulates the β-cell redox circuitry and enhances the sensitivity of β-cell metabolic pathways to glucose and GSIS under normal conditions as well as under hyperglycemia. This action is associated with the ability of TQ to regulate carbohydrate-to-lipid flux via downregulation of ACC and malonyl-CoA. PMID:26786775

Search, capture and signal: games microtubules and centrosomes play.

PubMed

Schuyler, S C; Pellman, D

2001-01-01

Accurate distribution of the chromosomes in dividing cells requires coupling of cellular polarity cues with both the orientation of the mitotic spindle and cell cycle progression. Work in budding yeast has demonstrated that cytoplasmic dynein and the kinesin Kip3p define redundant pathways that ensure proper spindle orientation. Furthermore, it has been shown that the Kip3p pathway components Kar9p and Bim1p (Yeb1p) form a complex that provides a molecular link between cortical polarity cues and spindle microtubules. Recently, other studies indicated that the cortical localization of Kar9p depends upon actin cables and Myo2p, a type V myosin. In addition, a BUB2-dependent cell cycle checkpoint has been described that inhibits the mitotic exit network and cytokinesis until proper centrosome position is achieved. Combined, these studies provide molecular insight into how cells link cellular polarity, spindle position and cell cycle progression.

Inhibitory effects of α-pinene on hepatoma carcinoma cell proliferation.

PubMed

Chen, Wei-Qiang; Xu, Bin; Mao, Jian-Wen; Wei, Feng-Xiang; Li, Ming; Liu, Tao; Jin, Xiao-Bao; Zhang, Li-Rong

2014-01-01

Pine needle oil from crude extract of pine needles has anti-tumor effects, but the effective component is not known. In the present study, compounds from a steam distillation extract of pine needles were isolated and characterized. Alpha-pinene was identified as an active anti-proliferative compound on hepatoma carcinoma BEL-7402 cells using the MTT assay. Further experiments showed that α-pinene inhibited BEL-7402 cells by arresting cell growth in the G2/M phase of the cell cycle, downregulating Cdc25C mRNA and protein expression, and reducing cycle dependence on kinase 1(CDK1) activity. Taken together, these findings indicate that α-pinene may be useful as a potential anti-tumor drug.

Practical high temperature (80 °C) storage study of industrially manufactured Li-ion batteries with varying electrolytes

NASA Astrophysics Data System (ADS)

Genieser, R.; Loveridge, M.; Bhagat, R.

2018-05-01

A previous study is focused on high temperature cycling of industrially manufactured Li-ion pouch cells (NMC-111/Graphite) with different electrolytes at 80 °C [JPS 373 (2018) 172-183]. Within this article the same test set-up is used, with cells stored for 30 days at different open circuit potentials and various electrolytes instead of electrochemical cycling. The most pronounced cell degradation (capacity fade and resistance increase) happens at high potentials. However appropriate electrolyte formulations are able to suppress ageing conditions by forming passivating surface films on both electrodes. Compared with electrochemical cycling at 80 °C, cells with enhanced electrolytes only show a slight resistance increase during storage and the capacity fade is much lower. Additionally it is shown for the first time, that the resistance is decreasing and capacity is regained once these cells are cycled again at room temperature. This is not the case for electrolytes without additives or just vinylene carbonate (VC) as an additive. It is further shown that the resistance increase of cells with the other electrolytes is accompanied by a reduction of the cell volume during further cycling. This behaviour is likely related to the reduction of CO2 at the anode to form additional SEI layer components.

The Notch pathway regulates the Second Mitotic Wave cell cycle independently of bHLH proteins.

PubMed

Bhattacharya, Abhishek; Li, Ke; Quiquand, Manon; Rimesso, Gerard; Baker, Nicholas E

2017-11-15

Notch regulates both neurogenesis and cell cycle activity to coordinate precursor cell generation in the differentiating Drosophila eye. Mosaic analysis with mitotic clones mutant for Notch components was used to identify the pathway of Notch signaling that regulates the cell cycle in the Second Mitotic Wave. Although S phase entry depends on Notch signaling and on the transcription factor Su(H), the transcriptional co-activator Mam and the bHLH repressor genes of the E(spl)-Complex were not essential, although these are Su(H) coactivators and targets during the regulation of neurogenesis. The Second Mitotic Wave showed little dependence on ubiquitin ligases neuralized or mindbomb, and although the ligand Delta is required non-autonomously, partial cell cycle activity occurred in the absence of known Notch ligands. We found that myc was not essential for the Second Mitotic Wave. The Second Mitotic Wave did not require the HLH protein Extra macrochaetae, and the bHLH protein Daughterless was required only cell-nonautonomously. Similar cell cycle phenotypes for Daughterless and Atonal were consistent with requirement for neuronal differentiation to stimulate Delta expression, affecting Notch activity in the Second Mitotic Wave indirectly. Therefore Notch signaling acts to regulate the Second Mitotic Wave without activating bHLH gene targets. Copyright © 2017 Elsevier Inc. All rights reserved.

DACH1 regulates cell cycle progression of myeloid cells through the control of cyclin D, Cdk 4/6 and p21{sup Cip1}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Jae-Woong; Kim, Hyeng-Soo; Kim, Seonggon

2012-03-30

Highlights: Black-Right-Pointing-Pointer DACH1 increases cyclin D, F and Cdk 1, 4, 6 in mouse myeloid progenitor cells. Black-Right-Pointing-Pointer The knockdown of DACH1 blocked the cell cycle progression of HL-60 cells. Black-Right-Pointing-Pointer The novel effect of DACH1 related with cell cycle regulation and leukemogenesis. -- Abstract: The cell-fate determination factor Dachshund, a component of the Retinal Determination Gene Network (RDGN), has a role in breast tumor proliferation through the repression of cyclin D1 and several key regulators of embryonic stem cell function, such as Nanog and Sox2. However, little is known about the role of DACH1 in a myeloid lineage asmore » a cell cycle regulator. Here, we identified the differential expression levels of extensive cell cycle regulators controlled by DACH1 in myeloid progenitor cells. The forced expression of DACH1 induced p27{sup Kip1} and repressed p21{sup Cip1}, which is a pivotal characteristic of the myeloid progenitor. Furthermore, DACH1 significantly increased the expression of cyclin D1, D3, F, and Cdk 1, 4, and 6 in myeloid progenitor cells. The knockdown of DACH1 blocked the cell cycle progression of HL-60 promyeloblastic cells through the decrease of cyclin D1, D3, F, and Cdk 1, 4, and 6 and increase in p21{sup Cip1}, which in turn decreased the phosphorylation of the Rb protein. The expression of Sox2, Oct4, and Klf4 was significantly up-regulated by the forced expression of DACH1 in mouse myeloid progenitor cells.« less

Characterization of physiochemical properties of polymeric and electrochemical materials for aerospace flight

NASA Technical Reports Server (NTRS)

Rock, M.; Kunigahalli, V.; Khan, S.; Mcnair, A.

1984-01-01

Nickel-cadmium rechargeable batteries are a vital and reliable energy storage source for aerospace applications. As the demand for longer life and more reliable space batteries increases, the understanding and solving of cell aging factors and mechanisms become essential. Over the years, many cell designs and manufacturing process changes have been developed and implemented. Cells fabricated with various design features were life cycled in a simulated low-Earth orbit regime. Following the test program, a comprehensive electrochemical analysis of cell components was undertaken to study cell degradation mechanisms. Discharge voltage degradation or voltage plateau has been observed during orbit cycling, but, its cause and explanation have been the subject of much discussion. A Hg/HgO reference electrode was used to monitor the reference versus each electrode potential during the discharge of a cycled cell. The results indicate that the negative electrode was responsible for the voltage plateau. Cell analysis revealed large crystals of cadmium hydroxide on the surface of the negative electrode and throughout the separator.

Cell module and fuel conditioner development

NASA Technical Reports Server (NTRS)

Feret, J. M.

1982-01-01

The efforts performed to develop a phosphoric acid fuel cell (PAFC) stack design having a 10 kW power rating for operation at higher than atmospheric pressure based on the existing Mark II design configuration are described. The work involves: (1) Performance of pertinent functional analysis, trade studies and thermodynamic cycle analysis for requirements definition and system operating parameter selection purposes, (2) characterization of fuel cell materials and components, and performance testing and evaluation of the repeating electrode components, (3) establishment of the state-of-the-art manufacturing technology for all fuel cell components at Westinghouse and the fabrication of short stacks of various sites, and (4) development of a 10 kW PAFC stack design for higher pressure operation utilizing the top down systems engineering approach.

Relocation of mitochondria to the prospective dorsal marginal zone during Xenopus embryogenesis

NASA Technical Reports Server (NTRS)

Yost, H. J.; Phillips, C. R.; Boore, J. L.; Bertman, J.; Whalon, B.; Danilchik, M. V.

1995-01-01

Dorsal-ventral axis formation in Xenopus laevis begins with a cytoplasmic rotation during the first cell cycle and culminates in a series of cell interactions and movements during gastrulation and neurulation that lead to the formation of dorsal-anterior structures. Evidence reported here indicates that mitochondria are differentially redistributed along the prospective dorsal-ventral axis as a consequence of the cortical-cytoplasmic rotation during the first cell cycle. This finding reinvigorates a possibility that has been considered for many years: asymmetries in cytoplasmic components and metabolic activities contribute to the development of morphological asymmetries.

Phosphatidylcholine catabolism in the MCF-7 cell cycle.

PubMed

Lin, Weiyang; Arthur, Gilbert

2006-10-01

The catabolism of phosphatidylcholine (PtdCho) appears to play a key role in regulating the net accumulation of the lipid in the cell cycle. Current protocols for measuring the degradation of PtdCho at specific cell-cycle phases require prolonged periods of incubation with radiolabelled choline. To measure the degradation of PtdCho at the S and G2 phases in the MCF-7 cell cycle, protocols were developed with radiolabelled lysophosphatidylcholine (lysoPtdCho), which reduces the labelling period and minimizes the recycling of labelled components. Although most of the incubated lysoPtdCho was hydrolyzed to glycerophosphocholine (GroPCho) in the medium, the kinetics of the incorporation of label into PtdCho suggests that the labelled GroPCho did not contribute significantly to cellular PtdCho formation. A protocol which involved exposing the cells twice to hydroxyurea, was also developed to produce highly synchronized MCF-7 cells with a profile of G1:S:G2/M of 90:5:5. An analysis of PtdCho catabolism in the synchronized cells following labelling with lysoPtdCho revealed that there was increased degradation of PtdCho in early to mid-S phase, which was attenuated in the G2/M phase. The results suggest that the net accumulation of PtdCho in MCF-7 cells may occur in the G2 phase of the cell cycle.

Fuel cell system modeling for solid oxide fuel cell/gas turbine hybrid power plants, Part I: Modeling and simulation framework

NASA Astrophysics Data System (ADS)

Leucht, Florian; Bessler, Wolfgang G.; Kallo, Josef; Friedrich, K. Andreas; Müller-Steinhagen, H.

A sustainable future power supply requires high fuel-to-electricity conversion efficiencies even in small-scale power plants. A promising technology to reach this goal is a hybrid power plant in which a gas turbine (GT) is coupled with a solid oxide fuel cell (SOFC). This paper presents a dynamic model of a pressurized SOFC system consisting of the fuel cell stack with combustion zone and balance-of-plant components such as desulphurization, humidification, reformer, ejector and heat exchangers. The model includes thermal coupling between the different components. A number of control loops for fuel and air flows as well as power management are integrated in order to keep the system within the desired operation window. Models and controls are implemented in a MATLAB/SIMULINK environment. Different hybrid cycles proposed earlier are discussed and a preferred cycle is developed. Simulation results show the prospects of the developed modeling and control system.

Comparative proteomics of two life cycle stages of stable isotope-labeled Trypanosoma brucei reveals novel components of the parasite's host adaptation machinery.

PubMed

Butter, Falk; Bucerius, Ferdinand; Michel, Margaux; Cicova, Zdenka; Mann, Matthias; Janzen, Christian J

2013-01-01

Trypanosoma brucei developed a sophisticated life cycle to adapt to different host environments. Although developmental differentiation of T. brucei has been the topic of intensive research for decades, the mechanisms responsible for adaptation to different host environments are not well understood. We developed stable isotope labeling by amino acids in cell culture in trypanosomes to compare the proteomes of two different life cycle stages. Quantitative comparison of 4364 protein groups identified many proteins previously not known to be stage-specifically expressed. The identification of stage-specific proteins helps to understand how parasites adapt to different hosts and provides new insights into differences in metabolism, gene regulation, and cell architecture. A DEAD-box RNA helicase, which is highly up-regulated in the bloodstream form of this parasite and which is essential for viability and proper cell cycle progression in this stage is described as an example.

Measuring In Vivo Protein Dynamics Throughout the Cell Cycle Using Microfluidics.

PubMed

de Leeuw, Roy; Brazda, Peter; Charl Moolman, M; Kerssemakers, J W J; Solano, Belen; Dekker, Nynke H

2017-01-01

Studying the dynamics of intracellular processes and investigating the interaction of individual macromolecules in live cells is one of the main objectives of cell biology. These macromolecules move, assemble, disassemble, and reorganize themselves in distinct manners under specific physiological conditions throughout the cell cycle. Therefore, in vivo experimental methods that enable the study of individual molecules inside cells at controlled culturing conditions have proved to be powerful tools to obtain insights into the molecular roles of these macromolecules and how their individual behavior influence cell physiology. The importance of controlled experimental conditions is enhanced when the investigated phenomenon covers long time periods, or perhaps multiple cell cycles. An example is the detection and quantification of proteins during bacterial DNA replication. Wide-field microscopy combined with microfluidics is a suitable technique for this. During fluorescence experiments, microfluidics offer well-defined cellular orientation and immobilization, flow and medium interchangeability, and high-throughput long-term experimentation of cells. Here we present a protocol for the combined use of wide-field microscopy and microfluidics for the study of proteins of the Escherichia coli DNA replication process. We discuss the preparation and application of a microfluidic device, data acquisition steps, and image analysis procedures to determine the stoichiometry and dynamics of a replisome component throughout the cell cycle of live bacterial cells.

Cellular plasticity enables adaptation to unforeseen cell-cycle rewiring challenges.

PubMed

Katzir, Yair; Stolovicki, Elad; Stern, Shay; Braun, Erez

2012-01-01

The fundamental dynamics of the cell cycle, underlying cell growth and reproduction, were previously found to be robust under a wide range of environmental and internal perturbations. This property was commonly attributed to its network structure, which enables the coordinated interactions among hundreds of proteins. Despite significant advances in deciphering the components and autonomous interactions of this network, understanding the interfaces of the cell cycle with other major cellular processes is still lacking. To gain insight into these interfaces, we used the process of genome-rewiring in yeast by placing an essential metabolic gene HIS3 from the histidine biosynthesis pathway, under the exclusive regulation of different cell-cycle promoters. In a medium lacking histidine and under partial inhibition of the HIS3p, the rewired cells encountered an unforeseen multitasking challenge; the cell-cycle regulatory genes were required to regulate the essential histidine-pathway gene in concert with the other metabolic demands, while simultaneously driving the cell cycle through its proper temporal phases. We show here that chemostat cell populations with rewired cell-cycle promoters adapted within a short time to accommodate the inhibition of HIS3p and stabilized a new phenotypic state. Furthermore, a significant fraction of the population was able to adapt and grow into mature colonies on plates under such inhibiting conditions. The adapted state was shown to be stably inherited across generations. These adaptation dynamics were accompanied by a non-specific and irreproducible genome-wide transcriptional response. Adaptation of the cell-cycle attests to its multitasking capabilities and flexible interface with cellular metabolic processes and requirements. Similar adaptation features were found in our previous work when rewiring HIS3 to the GAL system and switching cells from galactose to glucose. Thus, at the basis of cellular plasticity is the emergence of a yet-unknown general, non-specific mechanism allowing fast inherited adaptation to unforeseen challenges.

The 1985 Goddard Space Flight Center Battery Workshop

NASA Technical Reports Server (NTRS)

Morrow, G. (Editor)

1986-01-01

The subjects covered include: advanced energy storage, lithium cell technology, nickel-cadmium design evaluation and component testing, simulated orbital cycling and flight experience, and nickel-hydrogen technology.

The 4-Celled Tetrabaena socialis Nuclear Genome Reveals the Essential Components for Genetic Control of Cell Number at the Origin of Multicellularity in the Volvocine Lineage.

PubMed

Featherston, Jonathan; Arakaki, Yoko; Hanschen, Erik R; Ferris, Patrick J; Michod, Richard E; Olson, Bradley J S C; Nozaki, Hisayoshi; Durand, Pierre M

2018-04-01

Multicellularity is the premier example of a major evolutionary transition in individuality and was a foundational event in the evolution of macroscopic biodiversity. The volvocine chlorophyte lineage is well suited for studying this process. Extant members span unicellular, simple colonial, and obligate multicellular taxa with germ-soma differentiation. Here, we report the nuclear genome sequence of one of the most morphologically simple organisms in this lineage-the 4-celled colonial Tetrabaena socialis and compare this to the three other complete volvocine nuclear genomes. Using conservative estimates of gene family expansions a minimal set of expanded gene families was identified that associate with the origin of multicellularity. These families are rich in genes related to developmental processes. A subset of these families is lineage specific, which suggests that at a genomic level the evolution of multicellularity also includes lineage-specific molecular developments. Multiple points of evidence associate modifications to the ubiquitin proteasomal pathway (UPP) with the beginning of coloniality. Genes undergoing positive or accelerating selection in the multicellular volvocines were found to be enriched in components of the UPP and gene families gained at the origin of multicellularity include components of the UPP. A defining feature of colonial/multicellular life cycles is the genetic control of cell number. The genomic data presented here, which includes diversification of cell cycle genes and modifications to the UPP, align the genetic components with the evolution of this trait.

Histological method for evaluation of the efficiency of Enerlit-Clima.

PubMed

Gol'dshtein, D V; Vikhlyantseva, E V; Sakharova, N K; Maevskii, E I; Pogorelov, A G; Uchitel', M L

2004-08-01

We propose a method of evaluation of anticlimacteric efficiency of a drug by its effect on the estrous cycle. The study was carried out on 9-month-old mice with retained, but notably reduced reproductive function. Analysis of the cell components of the estrous cycle was carried out on histological preparations of vaginal smears.

Molecular identification of PpHDAC1, the first histone deacetylase fron the slime mold Physarum polycephalum.

PubMed

Brandtner, Eva-Maria; Lechner, Thomas; Loidl, Peter; Lusser, Alexandra

2002-01-01

The dynamic state of post-translational acetylation of eukaryotic histones is maintained by histone acetyltransferases (HATs) and histone deacetylases (HDACs). HATs and HDACs have been shown to be components of various regulatory protein complexes in the cell. Their enzymatic activities, intracellular localization and substrate specificities are regulated in a complex, cell cycle related manner. In the myxomycete Physarum polycephalum multiple HATs and HDACs can be distinguished in biochemical terms and they exhibit dynamic activity patterns depending on the cell cycle stage. Here we report on the cloning of the first P. polycephalum HDAC (PpHDAC1) related to the S. cerevisiae Rpd3 protein. The expression pattern of PpHDAC1 mRNA was analysed at different time points of the cell cycle and found to be largely constant. Treatment of macroplasmodia with the HDAC inhibitor trichostatin A at several cell cycle stages resulted in a significant delay in entry into mitosis of treated versus untreated plasmodia. No effect of TSA treatment could be observed on PpHDAC1 expression itself.

Solid oxide fuel cell power plant having a bootstrap start-up system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lines, Michael T

The bootstrap start-up system (42) achieves an efficient start-up of the power plant (10) that minimizes formation of soot within a reformed hydrogen rich fuel. A burner (48) receives un-reformed fuel directly from the fuel supply (30) and combusts the fuel to heat cathode air which then heats an electrolyte (24) within the fuel cell (12). A dilute hydrogen forming gas (68) cycles through a sealed heat-cycling loop (66) to transfer heat and generated steam from an anode side (32) of the electrolyte (24) through fuel processing system (36) components (38, 40) and back to an anode flow field (26)more » until fuel processing system components (38, 40) achieve predetermined optimal temperatures and steam content. Then, the heat-cycling loop (66) is unsealed and the un-reformed fuel is admitted into the fuel processing system (36) and anode flow (26) field to commence ordinary operation of the power plant (10).« less

The zebrafish maternal-effect gene cellular atoll encodes the centriolar component sas-6 and defects in its paternal function promote whole genome duplication.

PubMed

Yabe, Taijiro; Ge, Xiaoyan; Pelegri, Francisco

2007-12-01

A female-sterile zebrafish maternal-effect mutation in cellular atoll (cea) results in defects in the initiation of cell division starting at the second cell division cycle. This phenomenon is caused by defects in centrosome duplication, which in turn affect the formation of a bipolar spindle. We show that cea encodes the centriolar coiled-coil protein Sas-6, and that zebrafish Cea/Sas-6 protein localizes to centrosomes. cea also has a genetic paternal contribution, which when mutated results in an arrested first cell division followed by normal cleavage. Our data supports the idea that, in zebrafish, paternally inherited centrosomes are required for the first cell division while maternally derived factors are required for centrosomal duplication and cell divisions in subsequent cell cycles. DNA synthesis ensues in the absence of centrosome duplication, and the one-cycle delay in the first cell division caused by cea mutant sperm leads to whole genome duplication. We discuss the potential implications of these findings with regards to the origin of polyploidization in animal species. In addition, the uncoupling of developmental time and cell division count caused by the cea mutation suggests the presence of a time window, normally corresponding to the first two cell cycles, which is permissive for germ plasm recruitment.

Acetylation of Mammalian ADA3 Is Required for Its Functional Roles in Histone Acetylation and Cell Proliferation.

PubMed

Mohibi, Shakur; Srivastava, Shashank; Bele, Aditya; Mirza, Sameer; Band, Hamid; Band, Vimla

2016-10-01

Alteration/deficiency in activation 3 (ADA3) is an essential component of specific histone acetyltransferase (HAT) complexes. We have previously shown that ADA3 is required for establishing global histone acetylation patterns and for normal cell cycle progression (S. Mohibi et al., J Biol Chem 287:29442-29456, 2012, http://dx.doi.org/10.1074/jbc.M112.378901). Here, we report that these functional roles of ADA3 require its acetylation. We show that ADA3 acetylation, which is dynamically regulated in a cell cycle-dependent manner, reflects a balance of coordinated actions of its associated HATs, GCN5, PCAF, and p300, and a new partner that we define, the deacetylase SIRT1. We use mass spectrometry and site-directed mutagenesis to identify major sites of ADA3 acetylated by GCN5 and p300. Acetylation-defective mutants are capable of interacting with HATs and other components of HAT complexes but are deficient in their ability to restore ADA3-dependent global or locus-specific histone acetylation marks and cell proliferation in Ada3-deleted murine embryonic fibroblasts (MEFs). Given the key importance of ADA3-containing HAT complexes in the regulation of various biological processes, including the cell cycle, our study presents a novel mechanism to regulate the function of these complexes through dynamic ADA3 acetylation. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Acetylation of Mammalian ADA3 Is Required for Its Functional Roles in Histone Acetylation and Cell Proliferation

PubMed Central

Mohibi, Shakur; Srivastava, Shashank; Bele, Aditya; Mirza, Sameer; Band, Hamid

2016-01-01

Alteration/deficiency in activation 3 (ADA3) is an essential component of specific histone acetyltransferase (HAT) complexes. We have previously shown that ADA3 is required for establishing global histone acetylation patterns and for normal cell cycle progression (S. Mohibi et al., J Biol Chem 287:29442–29456, 2012, http://dx.doi.org/10.1074/jbc.M112.378901). Here, we report that these functional roles of ADA3 require its acetylation. We show that ADA3 acetylation, which is dynamically regulated in a cell cycle-dependent manner, reflects a balance of coordinated actions of its associated HATs, GCN5, PCAF, and p300, and a new partner that we define, the deacetylase SIRT1. We use mass spectrometry and site-directed mutagenesis to identify major sites of ADA3 acetylated by GCN5 and p300. Acetylation-defective mutants are capable of interacting with HATs and other components of HAT complexes but are deficient in their ability to restore ADA3-dependent global or locus-specific histone acetylation marks and cell proliferation in Ada3-deleted murine embryonic fibroblasts (MEFs). Given the key importance of ADA3-containing HAT complexes in the regulation of various biological processes, including the cell cycle, our study presents a novel mechanism to regulate the function of these complexes through dynamic ADA3 acetylation. PMID:27402865

Sinorhizobium meliloti CtrA Stability Is Regulated in a CbrA-Dependent Manner That Is Influenced by CpdR1

PubMed Central

Schallies, Karla B.; Sadowski, Craig; Meng, Julia; Chien, Peter

2015-01-01

ABSTRACT CbrA is a DivJ/PleC-like histidine kinase of DivK that is required for cell cycle progression and symbiosis in the alphaproteobacterium Sinorhizobium meliloti. Loss of cbrA results in increased levels of CtrA as well as its phosphorylation. While many of the known Caulobacter crescentus regulators of CtrA phosphorylation and proteolysis are phylogenetically conserved within S. meliloti, the latter lacks the PopA regulator that is required for CtrA degradation in C. crescentus. In order to investigate whether CtrA proteolysis occurs in S. meliloti, CtrA stability was assessed. During exponential growth, CtrA is unstable and therefore likely to be degraded in a cell cycle-regulated manner. Loss of cbrA significantly increases CtrA stability, but this phenotype is restored to that of the wild type by constitutive ectopic expression of a CpdR1 variant that cannot be phosphorylated (CpdR1D53A). Addition of CpdR1D53A fully suppresses cbrA mutant cell cycle defects, consistent with regulation of CtrA stability playing a key role in mediating proper cell cycle progression in S. meliloti. Importantly, the cbrA mutant symbiosis defect is also suppressed in the presence of CpdR1D53A. Thus, regulation of CtrA stability by CbrA and CpdR1 is associated with free-living cell cycle outcomes and symbiosis. IMPORTANCE The cell cycle is a fundamental process required for bacterial growth, reproduction, and developmental differentiation. Our objective is to understand how a two-component signal transduction network directs cell cycle events during free-living growth and host colonization. The Sinorhizobium meliloti nitrogen-fixing symbiosis with plants is associated with novel cell cycle events. This study identifies a link between the regulated stability of an essential response regulator, free-living cell cycle progression, and symbiosis. PMID:25897034

N-acetylcysteine normalizes the urea cycle and DNA repair in cells from patients with Batten disease.

PubMed

Kim, June-Bum; Lim, Nary; Kim, Sung-Jo; Heo, Tae-Hwe

2012-12-01

Batten disease is an inherited disorder characterized by early onset neurodegeneration due to the mutation of the CLN3 gene. The function of the CLN3 protein is not clear, but an association with oxidative stress has been proposed. Oxidative stress and DNA damage play critical roles in the pathogenesis of neurodegenerative diseases. Antioxidants are of interest because of their therapeutic potential for treating neurodegenerative diseases. We tested whether N-acetylcysteine (NAC), a well-known antioxidant, improves the pathology of cells from patients with Batten disease. At first, the expression levels of urea cycle components and DNA repair enzymes were compared between Batten disease cells and normal cells. We used both mRNA expression levels and Western blot analysis. We found that carbamoyl phosphate synthetase 1, an enzyme involved in the urea cycle, 8-oxoguanine DNA glycosylase 1 and DNA polymerase beta, enzymes involved in DNA repair, were expressed at higher levels in Batten disease cells than in normal cells. The treatment of Batten disease cells with NAC for 48 h attenuated activities of the urea cycle and of DNA repair, as indicated by the substantially decreased expression levels of carbamoyl phosphate synthetase 1, 8-oxoguanine DNA glycosylase 1 and DNA polymerase beta proteins compared with untreated Batten cells. NAC may serve in alleviating the burden of urea cycle and DNA repair processes in Batten disease cells. We propose that NAC may have beneficial effects in patients with Batten disease. Copyright © 2012 John Wiley & Sons, Ltd.

The Genetic Program of Pancreatic β-Cell Replication In Vivo

PubMed Central

Klochendler, Agnes; Caspi, Inbal; Corem, Noa; Moran, Maya; Friedlich, Oriel; Elgavish, Sharona; Nevo, Yuval; Helman, Aharon; Glaser, Benjamin; Eden, Amir; Itzkovitz, Shalev

2016-01-01

The molecular program underlying infrequent replication of pancreatic β-cells remains largely inaccessible. Using transgenic mice expressing green fluorescent protein in cycling cells, we sorted live, replicating β-cells and determined their transcriptome. Replicating β-cells upregulate hundreds of proliferation-related genes, along with many novel putative cell cycle components. Strikingly, genes involved in β-cell functions, namely, glucose sensing and insulin secretion, were repressed. Further studies using single-molecule RNA in situ hybridization revealed that in fact, replicating β-cells double the amount of RNA for most genes, but this upregulation excludes genes involved in β-cell function. These data suggest that the quiescence-proliferation transition involves global amplification of gene expression, except for a subset of tissue-specific genes, which are “left behind” and whose relative mRNA amount decreases. Our work provides a unique resource for the study of replicating β-cells in vivo. PMID:26993067

Cell cycle arrest by prostaglandin A1 at the G1/S phase interface with up-regulation of oncogenes in S-49 cyc- cells

NASA Technical Reports Server (NTRS)

Hughes-Fulford, M.

1994-01-01

Our previous studies have implied that prostaglandins inhibit cell growth independent of cAMP. Recent reports, however, have suggested that prostaglandin arrest of the cell cycle may be mediated through protein kinase A. In this report, in order to eliminate the role of c-AMP in prostaglandin mediated cell cycle arrest, we use the -49 lymphoma variant (cyc-) cells that lack adenylate cyclase activity. We demonstrate that dimethyl prostaglandin A1 (dmPGA1) inhibits DNA synthesis and cell growth in cyc- cells. DNA synthesis is inhibited 42% by dmPGA1 (50 microM) despite the fact that this cell line lacks cellular components needed for cAMP generation. The ability to decrease DNA synthesis depends upon the specific prostaglandin structure with the most effective form possessing the alpha, beta unsaturated ketone ring. Dimethyl PGA1 is most effective in inhibiting DNA synthesis in cyc- cells, with prostaglandins PGE1 and PGB1 being less potent inhibitors of DNA synthesis. DmPGE2 caused a significant stimulation of DNA synthesis. S-49 cyc- variant cells exposed to (30-50 microns) dmPGA1, arrested in the G1 phase of the cell cycle within 24 h. This growth arrest was reversed when the prostaglandin was removed from the cultured cells; growth resumed within hours showing that this treatment is not toxic. The S-49 cyc- cells were chosen not only for their lack of adenylate cyclase activity, but also because their cell cycle has been extensively studied and time requirements for G1, S, G2, and M phases are known. Within hours after prostaglandin removal the cells resume active DNA synthesis, and cell number doubles within 15 h suggesting rapid entry into S-phase DNA synthesis from the G1 cell cycle block.(ABSTRACT TRUNCATED AT 250 WORDS).

Phosphatidylcholine and the CDP-Choline Cycle

PubMed Central

Fagone, Paolo; Jackowski, Suzanne

2012-01-01

The CDP-choline pathway of phosphatidylcholine (PtdCho) biosynthesis was first described more than 50 years ago. Investigation of the CDP-choline pathway in yeast provides a basis for understanding the CDP-choline pathway in mammals. PtdCho is considered as an intermediate in a cycle of synthesis and degradation, and the activity of a CDP-choline cycle is linked to subcellular membrane lipid movement. The components of the mammalian CDP-choline pathway include choline transport, choline kinase, phosphocholine cytidylyltransferase, and choline phosphotransferase activities. The protein isoforms and biochemical mechanisms of regulation of the pathway enzymes are related to their cell and tissue-specific functions. Regulated PtdCho turnover mediated by phospholipases or neuropathy target esterase participates in the mammalian CDP-choline cycle. Knockout mouse models define the biological functions of the CDP-choline cycle in mammalian cells and tissues. This article is part of a Special Issue entitled Phospholipids and Phospholipid Metabolism. PMID:23010477

Unsuspected task for an old team: succinate, fumarate and other Krebs cycle acids in metabolic remodeling.

PubMed

Bénit, Paule; Letouzé, Eric; Rak, Malgorzata; Aubry, Laetitia; Burnichon, Nelly; Favier, Judith; Gimenez-Roqueplo, Anne-Paule; Rustin, Pierre

2014-08-01

Seventy years from the formalization of the Krebs cycle as the central metabolic turntable sustaining the cell respiratory process, key functions of several of its intermediates, especially succinate and fumarate, have been recently uncovered. The presumably immutable organization of the cycle has been challenged by a number of observations, and the variable subcellular location of a number of its constitutive protein components is now well recognized, although yet unexplained. Nonetheless, the most striking observations have been made in the recent period while investigating human diseases, especially a set of specific cancers, revealing the crucial role of Krebs cycle intermediates as factors affecting genes methylation and thus cell remodeling. We review here the recent advances and persisting incognita about the role of Krebs cycle acids in diverse aspects of cellular life and human pathology. Copyright © 2014 Elsevier B.V. All rights reserved.

A mechanical cell disruption microfluidic platform based on an on-chip micropump.

PubMed

Cheng, Yinuo; Wang, Yue; Wang, Zhiyuan; Huang, Liang; Bi, Mingzhao; Xu, Wenxiao; Wang, Wenhui; Ye, Xiongying

2017-03-01

Cell disruption plays a vital role in detection of intracellular components which contain information about genetic and disease characteristics. In this paper, we demonstrate a novel microfluidic platform based on an on-chip micropump for mechanical cell disruption and sample transport. A 50  μ l cell sample can be effectively lysed through on-chip multi-disruption in 36 s without introducing any chemical agent and suffering from clogging by cellular debris. After 30 cycles of circulating disruption, 80.6% and 90.5% cell disruption rates were achieved for the HEK293 cell sample and human natural killer cell sample, respectively. Profiting from the feature of pump-on-chip, the highly integrated platform enables more convenient and cost-effective cell disruption for the analysis of intracellular components.

A mechanical cell disruption microfluidic platform based on an on-chip micropump

PubMed Central

Cheng, Yinuo; Wang, Yue; Wang, Zhiyuan; Bi, Mingzhao; Xu, Wenxiao; Ye, Xiongying

2017-01-01

Cell disruption plays a vital role in detection of intracellular components which contain information about genetic and disease characteristics. In this paper, we demonstrate a novel microfluidic platform based on an on-chip micropump for mechanical cell disruption and sample transport. A 50 μl cell sample can be effectively lysed through on-chip multi-disruption in 36 s without introducing any chemical agent and suffering from clogging by cellular debris. After 30 cycles of circulating disruption, 80.6% and 90.5% cell disruption rates were achieved for the HEK293 cell sample and human natural killer cell sample, respectively. Profiting from the feature of pump-on-chip, the highly integrated platform enables more convenient and cost-effective cell disruption for the analysis of intracellular components. PMID:28798848

Comparing shut-down strategies for proton exchange membrane fuel cells

NASA Astrophysics Data System (ADS)

Oyarce, Alejandro; Zakrisson, Erik; Ivity, Matthew; Lagergren, Carina; Ofstad, Axel Baumann; Bodén, Andreas; Lindbergh, Göran

2014-05-01

Application of system strategies for mitigating carbon corrosion of the catalyst support in proton exchange fuel cells (PEMFCs) is a requirement for PEMFC systems, especially in the case of systems for transport application undergoing thousands of start-ups and shut-downs (SU/SD) during its lifetime. This study compares several of the most common shut-down strategies for 1100 cycles SU/SD cycles at 70 °C and 80% RH using commercially available fuel cell components. Each cycle simulates a prolonged shut-down, i.e. finishing each cycle with air filled anode and cathode. Furthermore, all start-ups are unprotected, i.e. introducing the H2 rich gas into an air filled anode. Finally, each cycle also includes normal fuel cell operation at 0.5 A cm-2 using synthetic reformate/air. H2 purge of the cathode and O2 consumption using a load were found to be the most effective strategies. The degradation rate using the H2 purge strategy was 23 μV cycle-1 at 0.86 A cm-2 using H2 and air at the anode and cathode, respectively. This degradation rate may be regarded as a generally low value, especially considering that this value also includes the degradation rate caused by unprotected start-ups.

Functional analyses of interacting factors involved in both pre-mRNA splicing and cell cycle progression in Saccharomyces cerevisiae.

PubMed Central

Russell, C S; Ben-Yehuda, S; Dix, I; Kupiec, M; Beggs, J D

2000-01-01

Through a genetic screen to search for factors that interact with Prp17/Cdc40p, a protein involved in both cell cycle progression and pre-mRNA splicing, we identify three novel factors, which we call Syf1p, Syf2p, and Syf3 (SYnthetic lethal with cdc Forty). Here we present evidence that all three proteins are spliceosome associated, that they associate weakly or transiently with U6 and U5 snRNAs, and that Syf1p and Syf3p (also known as Clf1p) are required for pre-mRNA splicing. In addition we show that depletion of Syf1p or Syf3p results in cell cycle arrest at the G2/M transition. Thus, like Prp17/Cdc40p, Syf1p and Syf3p are involved in two distinct cellular processes. We discuss the likelihood that Syf1p, Syf2p, and Syf3p are components of a protein complex that assembles into spliceosomes and also regulates cell cycle progression. PMID:11105756

Functional analyses of interacting factors involved in both pre-mRNA splicing and cell cycle progression in Saccharomyces cerevisiae.

PubMed

Russell, C S; Ben-Yehuda, S; Dix, I; Kupiec, M; Beggs, J D

2000-11-01

Through a genetic screen to search for factors that interact with Prp17/Cdc40p, a protein involved in both cell cycle progression and pre-mRNA splicing, we identify three novel factors, which we call Syf1p, Syf2p, and Syf3 (SYnthetic lethal with cdc Forty). Here we present evidence that all three proteins are spliceosome associated, that they associate weakly or transiently with U6 and U5 snRNAs, and that Syf1p and Syf3p (also known as Clf1p) are required for pre-mRNA splicing. In addition we show that depletion of Syf1p or Syf3p results in cell cycle arrest at the G2/M transition. Thus, like Prp17/Cdc40p, Syf1p and Syf3p are involved in two distinct cellular processes. We discuss the likelihood that Syf1p, Syf2p, and Syf3p are components of a protein complex that assembles into spliceosomes and also regulates cell cycle progression.

RAD9-dependent G1 arrest defines a second checkpoint for damaged DNA in the cell cycle of Saccharomyces cerevisiae.

PubMed

Siede, W; Friedberg, A S; Friedberg, E C

1993-09-01

Exposure of the yeast Saccharomyces cerevisiae to ultraviolet (UV) light, the UV-mimetic chemical 4-nitroquinoline-1-oxide (4NQO), or gamma radiation after release from G1 arrest induced by alpha factor results in delayed resumption of the cell cycle. As is the case with G2 arrest following ionizing radiation damage [Weinert, T. A. & Hartwell, L. H. (1988) Science 241, 317-322], the normal execution of DNA damage-induced G1 arrest depends on a functional yeast RAD9 gene. We suggest that the RAD9 gene product may interact with cellular components common to the G1/S and G2/M transition points in the cell cycle of this yeast. These observations define a checkpoint in the eukaryotic cell cycle that may facilitate the repair of lesions that are otherwise processed to lethal and/or mutagenic damage during DNA replication. This checkpoint apparently operates after the mating pheromone-induced G1 arrest point but prior to replicative DNA synthesis, S phase-associated maximal induction of histone H2A mRNA, and bud emergence.

Macrophage/epithelium cross-talk regulates cell cycle progression and migration in pancreatic progenitors.

PubMed

Mussar, Kristin; Tucker, Andrew; McLennan, Linsey; Gearhart, Addie; Jimenez-Caliani, Antonio J; Cirulli, Vincenzo; Crisa, Laura

2014-01-01

Macrophages populate the mesenchymal compartment of all organs during embryogenesis and have been shown to support tissue organogenesis and regeneration by regulating remodeling of the extracellular microenvironment. Whether this mesenchymal component can also dictate select developmental decisions in epithelia is unknown. Here, using the embryonic pancreatic epithelium as model system, we show that macrophages drive the epithelium to execute two developmentally important choices, i.e. the exit from cell cycle and the acquisition of a migratory phenotype. We demonstrate that these developmental decisions are effectively imparted by macrophages activated toward an M2 fetal-like functional state, and involve modulation of the adhesion receptor NCAM and an uncommon "paired-less" isoform of the transcription factor PAX6 in the epithelium. Over-expression of this PAX6 variant in pancreatic epithelia controls both cell motility and cell cycle progression in a gene-dosage dependent fashion. Importantly, induction of these phenotypes in embryonic pancreatic transplants by M2 macrophages in vivo is associated with an increased frequency of endocrine-committed cells emerging from ductal progenitor pools. These results identify M2 macrophages as key effectors capable of coordinating epithelial cell cycle withdrawal and cell migration, two events critical to pancreatic progenitors' delamination and progression toward their differentiated fates.

A role for Sar1 and ARF1 GTPases during Golgi biogenesis in the protozoan parasite Trypanosoma brucei

PubMed Central

Yavuz, Sevil; Warren, Graham

2017-01-01

A single Golgi stack is duplicated and partitioned into two daughter cells during the cell cycle of the protozoan parasite Trypanosoma brucei. The source of components required to generate the new Golgi and the mechanism by which it forms are poorly understood. Using photoactivatable GFP, we show that the existing Golgi supplies components directly to the newly forming Golgi in both intact and semipermeabilized cells. The movement of a putative glycosyltransferase, GntB, requires the Sar1 and ARF1 GTPases in intact cells. In addition, we show that transfer of GntB from the existing Golgi to the new Golgi can be recapitulated in semipermeabilized cells and is sensitive to the GTP analogue GTPγS. We suggest that the existing Golgi is a key source of components required to form the new Golgi and that this process is regulated by small GTPases. PMID:28495798

Zim17/Tim15 links mitochondrial iron-sulfur cluster biosynthesis to nuclear genome stability.

PubMed

Díaz de la Loza, María Del Carmen; Gallardo, Mercedes; García-Rubio, María Luisa; Izquierdo, Alicia; Herrero, Enrique; Aguilera, Andrés; Wellinger, Ralf Erik

2011-08-01

Genomic instability is related to a wide-range of human diseases. Here, we show that mitochondrial iron-sulfur cluster biosynthesis is important for the maintenance of nuclear genome stability in Saccharomyces cerevisiae. Cells lacking the mitochondrial chaperone Zim17 (Tim15/Hep1), a component of the iron-sulfur biosynthesis machinery, have limited respiration activity, mimic the metabolic response to iron starvation and suffer a dramatic increase in nuclear genome recombination. Increased oxidative damage or deficient DNA repair do not account for the observed genomic hyperrecombination. Impaired cell-cycle progression and genetic interactions of ZIM17 with components of the RFC-like complex involved in mitotic checkpoints indicate that replicative stress causes hyperrecombination in zim17Δ mutants. Furthermore, nuclear accumulation of pre-ribosomal particles in zim17Δ mutants reinforces the importance of iron-sulfur clusters in normal ribosome biosynthesis. We propose that compromised ribosome biosynthesis and cell-cycle progression are interconnected, together contributing to replicative stress and nuclear genome instability in zim17Δ mutants.

The Hydra small ubiquitin-like modifier.

PubMed

Khan, Umair; Mehere, Prajwalini; Deivasigamani, Senthilkumar; Ratnaparkhi, Girish S

2013-09-01

SUMO is a protein posttranslational modifier. SUMO cycle components are believed to be conserved in all eukaryotes. Proteomic analyses have lead to the identification a wealth of SUMO targets that are involved in almost every cellular function in eukaryotes. In this article, we describe the characterization of SUMO Cycle components in Hydra, a Cnidarian with an ability to regenerate body parts. In cells, the translated SUMO polypeptide cannot conjugate to a substrate protein unless the C-terminal tail is cleaved, exposing the di-Glycine motif. This critical task is done by SUMO proteases that in addition to SUMO maturation are also involved in deconjugating SUMO from its substrate. We describe the identification, bioinformatics analysis, cloning, and biochemical characterization of Hydra SUMO cycle components, with a focus on SUMO and SUMO proteases. We demonstrate that the ability of SUMO proteases to process immature SUMO is conserved from Hydra to flies. A transgenic Hydra, expressing a SUMO-GFP fusion protein under a constitutive actin promoter, is generated in an attempt to monitor the SUMO Cycle in vivo as also to purify and identify SUMO targets in Hydra. Copyright © 2013 Wiley Periodicals, Inc.

Advances in ambient temperature secondary lithium cells

NASA Technical Reports Server (NTRS)

Subbarao, S.; Shen, D. H.; Deligiannis, F.; Huang, C-K.; Halpert, G.

1989-01-01

The goal is to develop secondary lithium cells with a 100 Wh/kg specific energy capable of 1000 cycles at 50 percent DOD. The approach towards meeting this goal initially focused on several basic issues related to the cell chemistry, selection of cathode materials and electrolytes and component development. The performance potential of Li-TiS2, Li-MoS3, Li-V6O13 and Li-NbSe3 electrochemical systems was examined. Among these four, the Li-TiS2 system was found to be the most promising system in terms of achievable specific energy and cycle life. Major advancements to date in the development of Li-TiS2 cells are in the areas of cathode processing technology, mixed solvent electrolytes, and cell assembly. A summary is given of these advances.

Nanosecond pulsed electric fields and the cell cycle

NASA Astrophysics Data System (ADS)

Mahlke, Megan A.

Exposure to nanosecond pulsed electrical fields (nsPEFs) can cause poration of external and internal cell membranes, DNA damage, and disassociation of cytoskeletal components, all of which are capable of disrupting a cell's ability to replicate. The phase of the cell cycle at the time of exposure is linked to differential sensitivities to nsPEFs across cell lines, as DNA structure, membrane elasticity, and cytoskeletal structure change dramatically during the cell cycle. Additionally, nsPEFs are capable of activating cell cycle checkpoints, which could lead to apoptosis or slow population growth. NsPEFs are emerging as a method for treating tumors via apoptotic induction; therefore, investigating the relevance of nsPEFs and the cell cycle could translate into improved efficacy in tumor treatment. Populations of Jurkat and Chinese Hamster Ovary (CHO) cells were examined post-exposure (10 ns pulse trains at 150kV/cm) by analysis of DNA content via propidium iodide staining and flow cytometric analysis at various time points (1, 6, and 12h post-exposure) to determine population distribution in cell cycle phases. Additionally, CHO and Jurkat cells were synchronized in G1/S and G2/M phases, pulsed, and analyzed to evaluate the role of cell cycle phase in survival of nsPEFs. CHO populations appeared similar to sham populations post-nsPEFs but exhibited arrest in the G1 phase at 6h after exposure. Jurkat cells exhibited increased cell death after nsPEFs compared to CHO cells but did not exhibit checkpoint arrest at any observed time point. The G1/S phase checkpoint is partially controlled by the action of p53; the lack of an active p53 response in Jurkat cells could contribute to their ability to pass this checkpoint and resist cell cycle arrest. Both cell lines exhibited increased sensitivity to nsPEFs in G2/M phase. Live imaging of CHO cells after nsPEF exposure supports the theory of G1/S phase arrest, as a reduced number of cells undergo mitosis within 24 h when compared to sham treated cells. CHO cells undergoing mitosis after exposure also exhibit improper separation of chromatids which could indicate loss of function of the mitotic spindle checkpoint. Activation and loss of function of checkpoints in CHO but not Jurkat cells after nsPEF exposure suggests that activation of cell cycle checkpoints could be important in defining the character of cell line specific recovery after nsPEF exposure. Moreover, the increased sensitivity in G2/M phase exhibited by both cell lines indicates that cell cycle phase is an important consideration during nsPEF exposure, particularly when aiming to induce apoptosis.

Impact of Helicobacter pylori on the healing process of the gastric barrier

PubMed Central

Mnich, Eliza; Kowalewicz-Kulbat, Magdalena; Sicińska, Paulina; Hinc, Krzysztof; Obuchowski, Michał; Gajewski, Adrian; Moran, Anthony P; Chmiela, Magdalena

2016-01-01

AIM To determine the impact of selected well defined Helicobacter pylori (H. pylori) antigens on gastric barrier cell turnover. METHODS In this study, using two cellular models of gastric epithelial cells and fibroblasts, we have focused on exploring the effects of well defined H. pylori soluble components such as glycine acid extract antigenic complex (GE), subunit A of urease (UreA), cytotoxin associated gene A protein (CagA) and lipopolysaccharide (LPS) on cell turnover by comparing the wound healing capacity of the cells in terms of their proliferative and metabolic activity as well as cell cycle distribution. Toxic effects of H. pylori components have been assessed in an association with damage to cell nuclei and inhibition of signal transducer and activator of transcription 3 (STAT3) phosphorylation. RESULTS We showed that H. pylori GE, CagA and UreA promoted regeneration of epithelial cells and fibroblasts, which is necessary for effective tissue healing. However, in vivo increased proliferative activity of these cells may constitute an increased risk of gastric neoplasia. In contrast, H. pylori LPS showed a dose-dependent influence on the process of wound healing. At a low concentration (1 ng/mL) H. pylori LPS accelerated of healing epithelial cells, which was linked to significantly enhanced cell proliferation and MTT reduction as well as lack of alterations in cell cycle and downregulation of epidermal growth factor (EGF) production as well as cell nuclei destruction. By comparison, H. pylori LPS at a high concentration (25 ng/mL) inhibited the process of wound repair, which was related to diminished proliferative activity of the cells, cell cycle arrest, destruction of cell nuclei and downregulation of the EGF/STAT3 signalling pathway. CONCLUSION In vivo H. pylori LPS driven effects might lead to the maintenance of chronic inflammatory response and pathological disorders on the level of the gastric mucosal barrier. PMID:27672275

A complex regulatory network coordinating cell cycles during C. elegans development is revealed by a genome-wide RNAi screen.

PubMed

Roy, Sarah H; Tobin, David V; Memar, Nadin; Beltz, Eleanor; Holmen, Jenna; Clayton, Joseph E; Chiu, Daniel J; Young, Laura D; Green, Travis H; Lubin, Isabella; Liu, Yuying; Conradt, Barbara; Saito, R Mako

2014-02-28

The development and homeostasis of multicellular animals requires precise coordination of cell division and differentiation. We performed a genome-wide RNA interference screen in Caenorhabditis elegans to reveal the components of a regulatory network that promotes developmentally programmed cell-cycle quiescence. The 107 identified genes are predicted to constitute regulatory networks that are conserved among higher animals because almost half of the genes are represented by clear human orthologs. Using a series of mutant backgrounds to assess their genetic activities, the RNA interference clones displaying similar properties were clustered to establish potential regulatory relationships within the network. This approach uncovered four distinct genetic pathways controlling cell-cycle entry during intestinal organogenesis. The enhanced phenotypes observed for animals carrying compound mutations attest to the collaboration between distinct mechanisms to ensure strict developmental regulation of cell cycles. Moreover, we characterized ubc-25, a gene encoding an E2 ubiquitin-conjugating enzyme whose human ortholog, UBE2Q2, is deregulated in several cancers. Our genetic analyses suggested that ubc-25 acts in a linear pathway with cul-1/Cul1, in parallel to pathways employing cki-1/p27 and lin-35/pRb to promote cell-cycle quiescence. Further investigation of the potential regulatory mechanism demonstrated that ubc-25 activity negatively regulates CYE-1/cyclin E protein abundance in vivo. Together, our results show that the ubc-25-mediated pathway acts within a complex network that integrates the actions of multiple molecular mechanisms to control cell cycles during development. Copyright © 2014 Roy et al.

Odf2-deficient mother centrioles lack distal/subdistal appendages and the ability to generate primary cilia.

PubMed

Ishikawa, Hiroaki; Kubo, Akiharu; Tsukita, Shoichiro; Tsukita, Sachiko

2005-05-01

Outer dense fibre 2 (Odf2; also known as cenexin) was initially identified as a main component of the sperm tail cytoskeleton, but was later shown to be a general scaffold protein that is specifically localized at the distal/subdistal appendages of mother centrioles. Here we show that Odf2 expression is suppressed in mouse F9 cells when both alleles of Odf2 genes are deleted. Unexpectedly, the cell cycle of Odf2(-/-) cells does not seem to be affected. Immunofluorescence and ultrathin-section electron microscopy reveals that in Odf2(-/-) cells, distal/subdistal appendages disappear from mother centrioles, making it difficult to distinguish mother from daughter centrioles. In Odf2(-/-) cells, however, the formation of primary cilia is completely suppressed, although approximately 25% of wild-type F9 cells are ciliated under the steady-state cell cycle. The loss of primary cilia in Odf2(-/-) F9 cells can be rescued by exogenous Odf2 expression. These findings indicate that Odf2 is indispensable for the formation of distal/subdistal appendages and the generation of primary cilia, but not for other cell-cycle-related centriolar functions.

Overexpression of the Ubiquilin-4 (UBQLN4) is Associated with Cell Cycle Arrest and Apoptosis in Human Normal Gastric Epithelial Cell Lines GES-1 Cells by Activation of the ERK Signaling Pathway

PubMed Central

Huang, Shengkai; Dong, Xin; Wang, Jia; Ding, Jie; Li, Yan; Li, Dongdong; Lin, Hong; Wang, Wenjie; Zhao, Mei

2018-01-01

Background Ubiquilin-4 (UBQLN4) is a component of the ubiquitin-proteasome system and regulates the degradation of many proteins implicated in pathological conditions. The aim of this study was to determine the role of UBQLN4 in regulating the proliferation and survival of the normal gastric epithelial cell line GES-1. Material/Methods We constructed GES-1 lines stably overexpressing UBQLN4 by lentiviral infection. Cell proliferation, apoptosis, and the cell cycle were analyzed using the MTT assay and flow cytometric assays. Phosphorylation of ERK, JNK, p38, and expression of cyclin D1 were detected by western blot analysis. Results Overexpression of UBQLN4 significantly reduced proliferation and induced G2/M phase arrest and apoptosis in GES-1 cells. Moreover, upregulation of UBQLN4 increased the expression of cyclin D1 and phosphorylated ERK, but not JNK or p38. Conclusions These data suggest that UBQLN4 may induce cell cycle arrest and apoptosis via activation of the ERK pathway and upregulation of cyclin D1 in GES-1 cells. PMID:29807370

COMSAT's destructive physical analysis of aerospace nickel-cadmium cells for NASA/Goddard Space Flight Center

NASA Technical Reports Server (NTRS)

Robbins, Kathleen M. B.; Rao, Gopalakrishna M.; Yi, Thomas Y.

1993-01-01

Over the past 5 years, COMSAT has performed numerous destructive physical analyses (DPA's) on NASA-Goddard-supplied nickel-cadmium (Ni/Cd) cells. The samples included activated but uncycled cells, wet stored cells, cycled cells, and anomalous cells. The DPA's provided visual, morphological, and chemical analyses of the cell components. The DPA data for the analyzed cells are presented. For the cells investigated, the leading cause of poor performance, as determined by DPA, has been poor negative electrode utilization, which resulted in negative-electrode-limiting operation.

Unexpected Voltage Fade in LMR-NMC Oxides Cycled below the "Activation" Plateau

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Y.; Bareno, J.; Bettge, M.

A common feature of lithium-excess layered oxides, nominally of composition xLi(2)MnO(3)center dot(1-x)LiMO2 (M = transition metal) is a high-voltage plateau (similar to 4.5 V vs. Li/Li+) in their capacity-voltage profile during the first delithiation cycle. This plateau is believed to result from activation of the Li2MnO3 component, which makes additional lithium available for electrochemical cycling. However, oxides cycled beyond this activation plateau are known to display voltage fade which is a continuous reduction in their equilibrium potential. In this article we show that these oxides display gradual voltage fade even on electrochemical cycling in voltage ranges well below the activationmore » plateau. The average fade is similar to 0.08 mV-cycle(-1) for Li(1.2)Ni(0.1)5Mn(0.5)5Co(0.1)O(2) vs. Li cells after 20 cycles in the 2-4.1 V range at 55 degrees C; a similar to 54 mV voltage hysteresis, expressed as the difference in average cell voltage between charge and discharge cycles, is also observed. The voltage fade results from a gradual accumulation of local spinel environments in the crystal structure. Some of these spinel sites result from lithium deficiencies during oxide synthesis and are likely to be at the particle surfaces; other sites result from the migration of transition metal atoms in the partially-delithiated LiMO2 component into the lithium planes during electrochemical cycling. The observed rate of voltage fade depends on a combination of factors that includes the phase equilibrium between the layered and spinel components and the kinetics of transition metal migration. (C) The Author(s) 2014. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. All rights reserved.« less

A Proteasome Cap Subunit Required for Spindle Pole Body Duplication in Yeast

PubMed Central

McDonald, Heather B.; Byers, Breck

1997-01-01

Proteasome-mediated protein degradation is a key regulatory mechanism in a diversity of complex processes, including the control of cell cycle progression. The selection of substrates for degradation clearly depends on the specificity of ubiquitination mechanisms, but further regulation may occur within the proteasomal 19S cap complexes, which attach to the ends of the 20S proteolytic core and are thought to control entry of substrates into the core. We have characterized a gene from Saccharomyces cerevisiae that displays extensive sequence similarity to members of a family of ATPases that are components of the 19S complex, including human subunit p42 and S. cerevisiae SUG1/ CIM3 and CIM5 products. This gene, termed PCS1 (for proteasomal cap subunit), is identical to the recently described SUG2 gene (Russell, S.J., U.G. Sathyanarayana, and S.A. Johnston. 1996. J. Biol. Chem. 271:32810– 32817). We have shown that PCS1 function is essential for viability. A temperature-sensitive pcs1 strain arrests principally in the second cycle after transfer to the restrictive temperature, blocking as large-budded cells with a G2 content of unsegregated DNA. EM reveals that each arrested pcs1 cell has failed to duplicate its spindle pole body (SPB), which becomes enlarged as in other monopolar mutants. Additionally, we have shown localization of a functional Pcs1–green fluorescent protein fusion to the nucleus throughout the cell cycle. We hypothesize that Pcs1p plays a role in the degradation of certain potentially nuclear component(s) in a manner that specifically is required for SPB duplication. PMID:9151663

Analysis of uncultured extremophilic snow algae by non-invasive single cell Raman spectroscopy

NASA Astrophysics Data System (ADS)

Beer, Thomas; Tanaka, Zuki; Netzter, Nathan; Rothschild, Lynn J.; Chen, Bin

2011-10-01

The study of life in extreme environments is a critical component of Astrobiology. But many of the so-called "extremophiles" are not readily cultivatable and therefore difficult to study under laboratory conditions. An example of such an extremophile is the snow alga Chlamydomonas cd. nivalis which expresses still unstudied secondary metabolites within its life cycle. In this paper, we present the first time the non-invasive single cell Raman spectroscopy of the life cycle dependent metabolite composition of C. nivalis. These secondary metabolites are likely related to the adaptation of C. nivalis to various stress factors. Normalized carotenoid Raman spectra intensities reveal characteristic ratio differences that allow identification of life cycle stages and putative secondary metabolites.

Proposed megakaryocytic regulon of p53: the genes engaged to control cell cycle and apoptosis during megakaryocytic differentiation

PubMed Central

Apostolidis, Pani A.; Lindsey, Stephan; Miller, William M.

2012-01-01

During endomitosis, megakaryocytes undergo several rounds of DNA synthesis without division leading to polyploidization. In primary megakaryocytes and in the megakaryocytic cell line CHRF, loss or knock-down of p53 enhances cell cycling and inhibits apoptosis, leading to increased polyploidization. To support the hypothesis that p53 suppresses megakaryocytic polyploidization, we show that stable expression of wild-type p53 in K562 cells (a p53-null cell line) attenuates the cells' ability to undergo polyploidization during megakaryocytic differentiation due to diminished DNA synthesis and greater apoptosis. This suggested that p53's effects during megakaryopoiesis are mediated through cell cycle- and apoptosis-related target genes, possibly by arresting DNA synthesis and promoting apoptosis. To identify candidate genes through which p53 mediates these effects, gene expression was compared between p53 knock-down (p53-KD) and control CHRF cells induced to undergo terminal megakaryocytic differentiation using microarray analysis. Among substantially downregulated p53 targets in p53-KD megakaryocytes were cell cycle regulators CDKN1A (p21) and PLK2, proapoptotic FAS, TNFRSF10B, CASP8, NOTCH1, TP53INP1, TP53I3, DRAM1, ZMAT3 and PHLDA3, DNA-damage-related RRM2B and SESN1, and actin component ACTA2, while antiapoptotic CKS1B, BCL2, GTSE1, and p53 family member TP63 were upregulated in p53-KD cells. Additionally, a number of cell cycle-related, proapoptotic, and cytoskeleton-related genes with known functions in megakaryocytes but not known to carry p53-responsive elements were differentially expressed between p53-KD and control CHRF cells. Our data support a model whereby p53 expression during megakaryopoiesis serves to control polyploidization and the transition from endomitosis to apoptosis by impeding cell cycling and promoting apoptosis. Furthermore, we identify a putative p53 regulon that is proposed to orchestrate these effects. PMID:22548738

Communication network in the follicular papilla and connective tissue sheath through gap junctions in human hair follicles.

PubMed

Iguchi, Makiko; Hara, Masahiro; Manome, Hideaki; Kobayasi, Hiromi; Tagami, Hachiro; Aiba, Setsuya

2003-06-01

Epithelial-mesenchymal interactions play a crucial role in the induction of life-long cyclic transformations of hair follicles. Many studies have already demonstrated several candidates for the soluble factors secreted from the mesenchymal components of the hair follicle, i.e. the follicular papilla (FP) and connective tissue sheath (CTS), which may be responsible for hair cycling. In this paper, we focused on cell-cell contact between FP cells (FPCs), between CTS cells (CTSCs), and between FPCs and CTSCs that may allow these mesenchymal components to function as a syncytium during hair cycling. Electron microscopic examination of the FP and the CTS obtained from human scalp revealed a tri-lamellar structure of the plasma membranes, which is a characteristic of gap junctions at the cell-cell contacting area. The immunohistochemical study with anticonnexin 43 Ab using a confocal laser scanning microscope demonstrated numerous spotted positive signals scattered throughout the FP. In the CTS, spotted positive signals were arranged linearly along the basement membrane of the hair follicle. In particular, these positive spots were aggregated in the transitional region between the FP and the CTS. By Western blot analysis of total protein extracts from the cultured FPCs and neonatal human dermal fibroblasts using anticonnexin 43 antibody, a positive band corresponding to connexin 43 was detected at 43 kDa on both the FPC lane and fibroblast lane. These findings suggest that the FP and the CTS form a communicating network through gap junctions, which may play a role in controlling the dynamic structural changes of hair follicles during hair cycling.

Erufosine simultaneously induces apoptosis and autophagy by modulating the Akt-mTOR signaling pathway in oral squamous cell carcinoma.

PubMed

Kapoor, Vaishali; Zaharieva, Maya M; Das, Satya N; Berger, Martin R

2012-06-01

We investigated the anticancer activity of erufosine in oral squamous carcinoma cell lines in terms of cell proliferation, colony formation, induction of autophagy/apoptosis, cell cycle and mTOR signaling pathway. Erufosine showed dose-dependent cytotoxicity in all cell lines, it induced autophagy as well as apoptosis, G2 cell cycle arrest and modulation of cyclin D1 expression. Further erufosine downregulated the phosphorylation of major components of mTOR pathway, like p-Akt at Ser473 and Thr308 residues, p-Raptor, p-mTOR, p-PRAS40 and its downstream substrates p-p70S6K and p-4EBP1 in a dose-dependent manner. The pre-treatment of tumor cells with p-mTOR siRNA increased cytotoxic effects of erufosine comparable to cisplatin but higher than rapamycin. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Lactoferricin treatment decreases the rate of cell proliferation of a human colon cancer cell line.

PubMed

Freiburghaus, C; Janicke, B; Lindmark-Månsson, H; Oredsson, S M; Paulsson, M A

2009-06-01

Food components modify the risk of cancer at a large number of sites but the mechanism of action is unknown. In the present investigation, we studied the effect of the peptide lactoferricin derived from bovine milk lactoferrin on human colon cancer CaCo-2 cells. The cells were either untreated or treated with 2.0, 0.2, or 0.02 microM lactoferricin. Cell cycle kinetics were investigated with a bromodeoxyuridine DNA flow cytometric method. The results show that lactoferricin treatment slightly but significantly prolonged the S phase of the cell cycle. Lactoferricin treatment lowered the level of cyclin E1, a protein involved in the regulation of genes required for G(1)/S transition and consequently for efficient S phase progression. The slight prolongation of the S phase resulted in a reduction of cell proliferation, which became more apparent after a long treatment time.

Effects of nanosecond pulsed electrical fields (nsPEFs) on the cell cycle of CHO and Jurkat cells

NASA Astrophysics Data System (ADS)

Mahlke, Megan A.; Navara, Christopher; Ibey, Bennett L.

2014-03-01

Exposure to nano-second pulsed electrical fields (nsPEFs) can cause poration of external and internal cell membranes, DNA damage, and disassociation of cytoskeletal components, all of which are capable of disrupting a cell's ability to replicate. Variations between cell lines in membrane and cytoskeletal structure as well as in survival of nsPEF exposure should correspond to unique line-dependent cell cycle effects. Additionally, phase of cell cycle during exposure may be linked to differential sensitivities to nsPEFs across cell lines, as DNA structure, membrane elasticity, and cytoskeletal structure change dramatically during the cell cycle. Populations of Jurkat and Chinese Hamster Ovary (CHO) cells were examined post-exposure (10 ns pulse trains at 150kV/cm) by analysis of DNA content via propidium iodide staining and flow cytometric analysis at various time points (1, 6, and 12h post-exposure) to determine population distribution in cell cycle phases. Additionally, CHO and Jurkat cells were synchronized in G1/S and G2/M phases, pulsed, and analyzed to evaluate role of cell cycle phase in survival of nsPEFs. CHO populations recovered similarly to sham populations postnsPEF exposure and did not exhibit a phase-specific change in response. Jurkat cells exhibited considerable apoptosis/necrosis in response to nsPEF exposure and were unable to recover and proliferate in a manner similar to sham exposed cells. Additionally, Jurkat cells appear to be more sensitive to nsPEFs in G2/M phases than in G1/S phases. Recovery of CHO populations suggests that nsPEFs do not inhibit proliferation in CHO cells; however, inhibition of Jurkat cells post-nsPEF exposure coupled with preferential cell death in G2/M phases suggest that cell cycle phase during exposure may be an important factor in determining nsPEF toxicity in certain cell lines. Interestingly, CHO cells have a more robust and rigid cytoskeleton than Jurkat cells which is thought to contribute to their ability to survive nsPEFs. The ability of the CHO cytoskeleton to recover and complete mitosis after nsPEF-induced damage in G2/M phase may be integral to the cell line's higher tolerance of nsPEF exposure.

The potential role of ribosomal protein S5 on cell cycle arrest and initiation of murine erythroleukemia cell differentiation.

PubMed

Matragkou, Christina N; Papachristou, Eleni T; Tezias, Sotirios S; Tsiftsoglou, Asterios S; Choli-Papadopoulou, Theodora; Vizirianakis, Ioannis S

2008-07-01

Evidence now exists to indicate that some ribosomal proteins besides being structural components of the ribosomal subunits are involved in the regulation of cell differentiation and apoptosis. As we have shown earlier, initiation of erythroid differentiation of murine erythroleukemia (MEL) cells is associated with transcriptional inactivation of genes encoding ribosomal RNAs and ribosomal proteins S5 (RPS5) and L35a. In this study, we extended these observations and investigated whether transfection of MEL cells with RPS5 cDNA affects the onset of initiation of erythroid maturation and their entrance in cell cycle arrest. Stably transfected MEL cloned cells (MEL-C14 and MEL-C56) were established and assessed for their capacity to produce RPS5 RNA transcript and its translated product. The impact of RPS5 cDNA transfection on the RPS5 gene expression patterns and the accumulation of RPS5 protein in inducible transfected MEL cells were correlated with their ability to: (a) initiate differentiation, (b) enter cell cycle arrest at G(1)/G(0) phase, and (c) modulate the level of cyclin-dependent kinases CDK2, CDK4, and CDK6. The data presented indicate that deregulation of RPS5 gene expression (constitutive expression) affects RPS5 protein level and delays both the onset of initiation of erythroid maturation and entrance in cell cycle arrest in inducer-treated MEL cells. 2008 Wiley-Liss, Inc.

Alpha-santalol, a chemopreventive agent against skin cancer, causes G2/M cell cycle arrest in both p53-mutated human epidermoid carcinoma A431 cells and p53 wild-type human melanoma UACC-62 cells

PubMed Central

2010-01-01

Background α-Santalol, an active component of sandalwood oil, has shown chemopreventive effects on skin cancer in different murine models. However, effects of α-santalol on cell cycle have not been studied. Thus, the objective of this study was to investigate effects of α-santalol on cell cycle progression in both p53 mutated human epidermoid carcinoma A431 cells and p53 wild-type human melanoma UACC-62 cells to elucidate the mechanism(s) of action. Methods MTT assay was used to determine cell viability in A431 cells and UACC-62; fluorescence-activated cell sorting (FACS) analysis of propidium iodide staining was used for determining cell cycle distribution in A431 cells and UACC-62 cells; immunoblotting was used for determining the expression of various proteins and protein complexes involved in the cell cycle progression; siRNA were used to knockdown of p21 or p53 in A431 and UACC-62 cells and immunofluorescence microscopy was used to investigate microtubules in UACC-62 cells. Results α-Santalol at 50-100 μM decreased cell viability from 24 h treatment and α-santalol at 50 μM-75 μM induced G2/M phase cell cycle arrest from 6 h treatment in both A431 and UACC-62 cells. α-Santalol altered expressions of cell cycle proteins such as cyclin A, cyclin B1, Cdc2, Cdc25c, p-Cdc25c and Cdk2. All of these proteins are critical for G2/M transition. α-Santalol treatment up-regulated the expression of p21 and suppressed expressions of mutated p53 in A431 cells; whereas, α-santalol treatment increased expressions of wild-type p53 in UACC-62 cells. Knockdown of p21 in A431 cells, knockdown of p21 and p53 in UACC-62 cells did not affect cell cycle arrest caused by α-santalol. Furthermore, α-santalol caused depolymerization of microtubules similar to vinblastine in UACC-62 cells. Conclusions This study for the first time identifies effects of α-santalol in G2/M phase arrest and describes detailed mechanisms of G2/M phase arrest by this agent, which might be contributing to its overall cancer preventive efficacy in various mouse skin cancer models. PMID:20682067

DNA fragmentation and cell cycle arrest: a hallmark of apoptosis induced by crocin from kashmiri saffron in a human pancreatic cancer cell line.

PubMed

Bakshi, Hamid; Sam, Smitha; Rozati, Roya; Sultan, Phalisteen; Islam, Tajamul; Rathore, Babita; Lone, Zahoor; Sharma, Manik; Triphati, Jagrati; Saxena, Ramesh Chand

2010-01-01

Apoptosis, a widely important mechanism that contributes to cell growth reduction, is reported to be induced by Crocus sativus in different cancer types. The present study was designed to elucidate apoptosis induction by crocin, a main component of Crocus sativus in a human pancreatic cancer cell line (BxPC-3). Cell viability was measured by MTT assay, Hoechest33258 staining was used to detect the chromatin condensation characteristic of apoptosis, and DNA fragmentation was assessed by gel electrophoresis and cell cycle analysis by flow cytometry. Crocin induced apoptosis and G1-phase cell cycle arrest of BxPC-3 cells, while decreasing cell viability in a dose dependent and time dependent manner. Cells treated with 10μg/L crocin exhibited apoptotic morphology (brightly blue-fluorescent condensed nuclei on Hoechst 33258 staining) and reduction of volume. DNA analysis revealed typical ladders as early as 12 hours after treatment indicative of apoptosis. Our preclinical study demonstrated a pancreatic cancer cell line to be highly sensitive to crocin-mediated growth inhibition and apoptotic cell death. Although the molecular mechanisms of crocin action are not yet clearly understood, it appears to have potential as a therapeutic agent.

The MAPK Signaling Cascade is a Central Hub in the Regulation of Cell Cycle, Apoptosis and Cytoskeleton Remodeling by Tripeptidyl-Peptidase II

PubMed Central

Sompallae, Ramakrishna; Stavropoulou, Vaia; Houde, Mathieu; Masucci, Maria G.

2008-01-01

Tripeptidyl-peptidase II (TPPII) is a serine peptidase highly expressed in malignant Burkitt’s lymphoma cells (BL). We have previously shown that overexpression of TPPII correlates with chromosomal instability, centrosomal and mitotic spindle abnormalities and resistance to apoptosis induced by spindle poisons. Furthermore, TPPII knockdown by RNAi was associated with endoreplication and the accumulation of polynucleated cells that failed to complete cell division, indicating a role of TPPII in the cell cycle. Here we have applied a global approach of gene expression analysis to gain insights on the mechanism by which TPPII regulates this phenotype. mRNA profiling of control and TPPII knockdown BL cells identified one hundred and eighty five differentially expressed genes. Functional categorization of these genes highlighted major physiological functions such as apoptosis, cell cycle progression, cytoskeleton remodeling, proteolysis, and signal transduction. Pathways and protein interactome analysis revealed a significant enrichment in components of MAP kinases signaling. These findings suggest that TPPII influences a wide network of signaling pathways that are regulated by MAPKs and exerts thereby a pleiotropic effect on biological processes associated with cell survival, proliferation and genomic instability. PMID:19787088

Cyclin C influences the timing of mitosis in fission yeast

PubMed Central

Banyai, Gabor; Szilagyi, Zsolt; Baraznenok, Vera; Khorosjutina, Olga; Gustafsson, Claes M.

2017-01-01

The multiprotein Mediator complex is required for the regulated transcription of nearly all RNA polymerase II–dependent genes. Mediator contains the Cdk8 regulatory subcomplex, which directs periodic transcription and influences cell cycle progression in fission yeast. Here we investigate the role of CycC, the cognate cyclin partner of Cdk8, in cell cycle control. Previous reports suggested that CycC interacts with other cellular Cdks, but a fusion of CycC to Cdk8 reported here did not cause any obvious cell cycle phenotypes. We find that Cdk8 and CycC interactions are stabilized within the Mediator complex and the activity of Cdk8-CycC is regulated by other Mediator components. Analysis of a mutant yeast strain reveals that CycC, together with Cdk8, primarily affects M-phase progression but mutations that release Cdk8 from CycC control also affect timing of entry into S phase. PMID:28515143

Global Identification of New Substrates for the Yeast Endoribonuclease, RNase Mitochondrial RNA Processing (MRP)*

PubMed Central

Aulds, Jason; Wierzbicki, Sara; McNairn, Adrian; Schmitt, Mark E.

2012-01-01

RNase mitochondrial RNA processing (MRP) is an essential, evolutionarily conserved endoribonuclease composed of 10 different protein subunits and a single RNA. RNase MRP has established roles in multiple pathways including ribosome biogenesis, cell cycle regulation, and mitochondrial DNA replication. Although each of these functions is important to cell growth, additional functions may exist given the essential nature of the complex. To identify novel RNase MRP substrates, we utilized RNA immunoprecipitation and microarray chip analysis to identify RNA that physically associates with RNase MRP. We identified several new potential substrates for RNase MRP including a cell cycle-regulated transcript, CTS1; the yeast homolog of the mammalian p27Kip1, SIC1; and the U2 RNA component of the spliceosome. In addition, we found RNase MRP to be involved in the regulation of the Ty1 transposon RNA. These results reinforce and broaden the role of RNase MRP in cell cycle regulation and help to identify new roles of this endoribonuclease. PMID:22977255

Global identification of new substrates for the yeast endoribonuclease, RNase mitochondrial RNA processing (MRP).

PubMed

Aulds, Jason; Wierzbicki, Sara; McNairn, Adrian; Schmitt, Mark E

2012-10-26

RNase mitochondrial RNA processing (MRP) is an essential, evolutionarily conserved endoribonuclease composed of 10 different protein subunits and a single RNA. RNase MRP has established roles in multiple pathways including ribosome biogenesis, cell cycle regulation, and mitochondrial DNA replication. Although each of these functions is important to cell growth, additional functions may exist given the essential nature of the complex. To identify novel RNase MRP substrates, we utilized RNA immunoprecipitation and microarray chip analysis to identify RNA that physically associates with RNase MRP. We identified several new potential substrates for RNase MRP including a cell cycle-regulated transcript, CTS1; the yeast homolog of the mammalian p27(Kip1), SIC1; and the U2 RNA component of the spliceosome. In addition, we found RNase MRP to be involved in the regulation of the Ty1 transposon RNA. These results reinforce and broaden the role of RNase MRP in cell cycle regulation and help to identify new roles of this endoribonuclease.

[Analysis of the role of various components of culture media during the proliferation of mouse neuroblastoma NIE-115 cells].

PubMed

Aslanidi, K B; Miakisheva, S N

2010-01-01

The values of the parameters of serum-free media (concentration of Na+, amino acids, and carbohydrates, as well as the pH values) have been determined at which the rate of the differentiation of neuroblastoma cells is minimal, and the rate of proliferation is maximal. It was shown that media inducing the differentiation of 70% of cells during the cell cycle provide the maximal time of survival of differentiated cells.

A novel miRNA-mediated STOP sign in lung cancer: miR-340 inhibits the proliferation of lung cancer cells through p27KIP1

PubMed Central

Fernandez, Serena; Risolino, Maurizio; Verde, Pasquale

2015-01-01

Oncosuppressor miRNAs inhibit cancer cell proliferation by targeting key components of the cell cycle machinery. In our recent report we showed that miR-340 is a novel tumor suppressor in non-small cell lung cancer. miR-340 inhibits neoplastic cell proliferation and induces p27KIP1 by targeting multiple translational and post-translational regulators of this cyclin-dependent kinase inhibitor. PMID:27308439

Improvement of the conductive network of positive electrodes and the performance of Ni-MH battery

NASA Astrophysics Data System (ADS)

Morimoto, Katsuya; Nakayama, Kousuke; Maki, Hideshi; Inoue, Hiroshi; Mizuhata, Minoru

2017-06-01

The pretreatment to modify the valence of cobalt by discharging at 0.2 C rate for 7.5 h before the first initial activation charge process is effective in improving the surface electronic conductivity among fine particles of positive electrode active materials. The discharge curves indicate the same locus within 1800 cycles, and the capacity of the pretreated battery is stable for over 4000 cycles. However, in-situ cell pretreatment with constant current has negative influence on other components. During the constant current pretreatment, the cell voltage rapidly falls to -0.5 V in the first 10 s of in-situ pretreatment. Therefore, we investigate the pretreatment by supplying a constant voltage to the battery instead of a constant current, and find the effective condition to improve the electrochemical performance and not to have any influence on other components of the battery.

Histone H2A is required for normal centromere function in Saccharomyces cerevisiae

PubMed Central

Pinto, Inés; Winston, Fred

2000-01-01

Histones are structural and functional components of the eukaryotic chromosome, and their function is essential for normal cell cycle progression. In this work, we describe the characterization of two Saccharomyces cerevisiae cold-sensitive histone H2A mutants. Both mutants contain single amino acid replacements of residues predicted to be on the surface of the nucleosome and in close contact with DNA. We show that these H2A mutations cause an increase-in-ploidy phenotype, an increased rate of chromosome loss, and a defect in traversing the G2–M phase of the cell cycle. Moreover, these H2A mutations show genetic interactions with mutations in genes encoding kinetochore components. Finally, chromatin analysis of these H2A mutants has revealed an altered centromeric chromatin structure. Taken together, these results strongly suggest that histone H2A is required for proper centromere–kinetochore function during chromosome segregation. PMID:10747028

Hemoglobin consumption by P. falciparum in individual erythrocytes imaged via quantitative phase spectroscopy

NASA Astrophysics Data System (ADS)

Rinehart, Matthew T.; Park, Han Sang; Walzer, Katelyn A.; Chi, Jen-Tsan Ashley; Wax, Adam

2016-04-01

Plasmodium falciparum infection causes structural and biochemical changes in red blood cells (RBCs). To quantify these changes, we apply a novel optical technique, quantitative phase spectroscopy (QPS) to characterize individual red blood cells (RBCs) during the intraerythrocytic life cycle of P. falciparum. QPS captures hyperspectral holograms of individual RBCs to measure spectroscopic changes across the visible wavelength range (475-700 nm), providing complex information, i.e. amplitude and phase, about the light field which has interacted with the cell. The complex field provides complimentary information on hemoglobin content and cell mass, which are both found to dramatically change upon infection by P. falciparum. Hb content progressively decreases with parasite life cycle, with an average 72.2% reduction observed for RBCs infected by schizont-stage P. falciparum compared to uninfected cells. Infection also resulted in a 33.1% reduction in RBC’s optical volume, a measure of the cells’ non-aqueous components. Notably, optical volume is only partially correlated with hemoglobin content, suggesting that changes in other dry mass components such as parasite mass may also be assessed using this technique. The unique ability of QPS to discriminate individual healthy and infected cells using spectroscopic changes indicates that the approach can be used to detect disease.

Robustness of synthetic oscillators in growing and dividing cells

NASA Astrophysics Data System (ADS)

Paijmans, Joris; Lubensky, David K.; Rein ten Wolde, Pieter

2017-05-01

Synthetic biology sets out to implement new functions in cells, and to develop a deeper understanding of biological design principles. Elowitz and Leibler [Nature (London) 403, 335 (2000), 10.1038/35002125] showed that by rational design of the reaction network, and using existing biological components, they could create a network that exhibits periodic gene expression, dubbed the repressilator. More recently, Stricker et al. [Nature (London) 456, 516 (2008), 10.1038/nature07389] presented another synthetic oscillator, called the dual-feedback oscillator, which is more stable. Detailed studies have been carried out to determine how the stability of these oscillators is affected by the intrinsic noise of the interactions between the components and the stochastic expression of their genes. However, as all biological oscillators reside in growing and dividing cells, an important question is how these oscillators are perturbed by the cell cycle. In previous work we showed that the periodic doubling of the gene copy numbers due to DNA replication can couple not only natural, circadian oscillators to the cell cycle [Paijmans et al., Proc. Natl. Acad. Sci. (USA) 113, 4063 (2016), 10.1073/pnas.1507291113], but also these synthetic oscillators. Here we expand this study. We find that the strength of the locking between oscillators depends not only on the positions of the genes on the chromosome, but also on the noise in the timing of gene replication: noise tends to weaken the coupling. Yet, even in the limit of high levels of noise in the replication times of the genes, both synthetic oscillators show clear signatures of locking to the cell cycle. This work enhances our understanding of the design of robust biological oscillators inside growing and diving cells.

The importance of amino sugar turnover to C and N cycling in organic horizons of old-growth Douglas-fir forest soils colonized by ectomycorrhizal mats

Treesearch

L. Zeglin; L.A. Kluber; D.D. Myrold

2012-01-01

Amino sugar dynamics represent an important but under-investigated component of the carbon (C) and nitrogen (N) cycles in old-growth Douglas-fir forest soils. Because fungal biomass is high in these soils, particularly in areas colonized by rhizomorphic ectomycorrhizal fungal mats, organic matter derived from chitinous cell wall material (or the monomeric building...

S-allyl derivatives of 6-mercaptopurine are highly potent drugs against human B-CLL through synergism between 6-mercaptopurine and allicin.

PubMed

Miron, Talia; Wilchek, Meir; Shvidel, Lev; Berrebi, Alain; Arditti, Fabian D

2012-12-01

S-allylthio-6-mercaptopurine and its ribose derivative were tested for anti-leukemic activity, using a human- mouse B-CLL model. The novel prodrugs contain two components, a purine analog, which interferes with DNA synthesis, and an S-allylthio, readily engaging in thiol-disulfide exchange reactions. The latter component targets the redox homeostasis which is more sensitive in leukemic cells, than in normal B-cells. Upon administration, the prodrug permeates cells, instantly reacts with free thiol, forming S-allyl mixed disulfides and releasing purine. Several cycles of thiol-disulfide exchange reactions occur, thus extending the duration of the prodrug effects. The concerted action of 2 components, as compared with purine alone, boosted in vitro apoptotis in B-CLL cells from 10% to 38%, and decreased in vivo engraftment of B-CLL from 30% to 0.7%. Copyright © 2012 Elsevier Ltd. All rights reserved.

Saccharomyces cerevisiae Gle2/Rae1 is involved in septin organization, essential for cell cycle progression.

PubMed

Zander, Gesa; Kramer, Wilfried; Seel, Anika; Krebber, Heike

2017-11-01

Gle2/Rae1 is highly conserved from yeast to humans and has been described as an mRNA export factor. Additionally, it is implicated in the anaphase-promoting complex-mediated cell cycle regulation in higher eukaryotes. Here we identify an involvement for Saccharomyces cerevisiae Gle2 in septin organization, which is crucial for cell cycle progression and cell division. Gle2 genetically and physically interacts with components of the septin ring. Importantly, deletion of GLE2 leads to elongated buds, severe defects in septin-assembly and their cellular mislocalization. Septin-ring formation is triggered by the septin-regulating GTPase Cdc42, which establishes and maintains cell polarity. Additionally, activity of the master cell cycle regulator Cdc28 (Cdk1) is needed, which is, besides other functions, also required for G 2 /M-transition, and in yeast particularly responsible for initiating the apical-isotropic switch. We show genetic and physical interactions of Gle2 with both Cdc42 and Cdc28. Most importantly, we find that gle2∆ severely mislocalizes Cdc42, leading to defects in septin-complex formation and cell division. Thus, our findings suggest that Gle2 participates in the efficient organization of the septin assembly network, where it might act as a scaffold protein. © 2017 The Authors. Yeast published by John Wiley & Sons, Ltd. © 2017 The Authors. Yeast published by John Wiley & Sons, Ltd.

Simulated microgravity, Mars gravity, and 2g hypergravity affect cell cycle regulation, ribosome biogenesis, and epigenetics in Arabidopsis cell cultures.

PubMed

Kamal, Khaled Y; Herranz, Raúl; van Loon, Jack J W A; Medina, F Javier

2018-04-23

Gravity is the only component of Earth environment that remained constant throughout the entire process of biological evolution. However, it is still unclear how gravity affects plant growth and development. In this study, an in vitro cell culture of Arabidopsis thaliana was exposed to different altered gravity conditions, namely simulated reduced gravity (simulated microgravity, simulated Mars gravity) and hypergravity (2g), to study changes in cell proliferation, cell growth, and epigenetics. The effects after 3, 14, and 24-hours of exposure were evaluated. The most relevant alterations were found in the 24-hour treatment, being more significant for simulated reduced gravity than hypergravity. Cell proliferation and growth were uncoupled under simulated reduced gravity, similarly, as found in meristematic cells from seedlings grown in real or simulated microgravity. The distribution of cell cycle phases was changed, as well as the levels and gene transcription of the tested cell cycle regulators. Ribosome biogenesis was decreased, according to levels and gene transcription of nucleolar proteins and the number of inactive nucleoli. Furthermore, we found alterations in the epigenetic modifications of chromatin. These results show that altered gravity effects include a serious disturbance of cell proliferation and growth, which are cellular functions essential for normal plant development.

A chemical screen in diverse breast cancer cell lines reveals genetic enhancers and suppressors of sensitivity to PI3K isotype-selective inhibition

PubMed Central

Torbett, Neil E; Luna, Antonio; Knight, Zachary A.; Houk, Andrew; Moasser, Mark; Weiss, William; Shokat, Kevan M.; Stokoe, David

2011-01-01

Synopsis The Phosphoinositide-3-kinase (PI3K) pathway regulates cell proliferation, survival and migration and is consequently of great interest for targeted cancer therapy. Using a panel of small molecule PI3K isoform-selective inhibitors in a diverse set of breast cancer cell lines, we demonstrate that the biochemical and biological responses were highly variable and dependent on the genetic alterations present. p110α inhibitors were generally effective in inhibiting the phosphorylation of Akt and S6, two downstream components of PI3K signaling, in most cell lines examined. In contrast, 110β selective inhibitors only reduced Akt phosphorylation in PTEN mutant cell lines, and was associated with a lesser decrease in S6 phosphorylation. PI3K inhibitors reduced cell viability by causing a cell cycle arrest in the G1 phase of the cell cycle, with multi-targeted inhibitors causing the most potent effects. Cells expressing mutant Ras were resistant to the cell cycle effects of PI3K inhibition, which could be reversed using inhibitors of Ras signaling pathways. Taken together our data indicates that these compounds, alone or in suitable combinations, may be useful as breast cancer therapeutics, when used in appropriate genetic contexts. PMID:18498248

Cells for bioartificial liver devices: the human hepatoma-derived cell line C3A produces urea but does not detoxify ammonia.

PubMed

Mavri-Damelin, Demetra; Damelin, Leonard H; Eaton, Simon; Rees, Myrddin; Selden, Clare; Hodgson, Humphrey J F

2008-02-15

Extrahepatic bioartificial liver devices should provide an intact urea cycle to detoxify ammonia. The C3A cell line, a subclone of the hepatoma-derived HepG2 cell line, is currently used in this context as it produces urea, and this has been assumed to be reflective of ammonia detoxification via a functional urea cycle. However, based on our previous findings of perturbed urea-cycle function in the non-urea producing HepG2 cell line, we hypothesized that the urea produced by C3A cells was via a urea cycle-independent mechanism, namely, due to arginase II activity, and therefore would not detoxify ammonia. Urea was quantified using (15)N-ammonium chloride metabolic labelling with gas chromatography-mass spectrometry. Gene expression was determined by real-time reverse transcriptase-PCR, protein expression by western blotting, and functional activities with radiolabelling enzyme assays. Arginase inhibition studies used N(omega)-hydroxy-nor-L-arginine. Urea was detected in C3A conditioned medium; however, (15)N-ammonium chloride-labelling indicated that (15)N-ammonia was not incorporated into (15)N-labelled urea. Further, gene expression of two urea cycle genes, ornithine transcarbamylase and arginase I, were completely absent. In contrast, arginase II mRNA and protein was expressed at high levels in C3A cells and was inhibited by N(omega)-hydroxy-nor-L-arginine, which prevented urea production, thereby indicating a urea cycle-independent pathway. The urea cycle is non-functional in C3A cells, and their urea production is solely due to the presence of arginase II, which therefore cannot provide ammonia detoxification in a bioartificial liver system. This emphasizes the continued requirement for developing a component capable of a full repertoire of liver function. (c) 2007 Wiley Periodicals, Inc.

53BP1 and USP28 mediate p53-dependent cell cycle arrest in response to centrosome loss and prolonged mitosis.

PubMed

Fong, Chii Shyang; Mazo, Gregory; Das, Tuhin; Goodman, Joshua; Kim, Minhee; O'Rourke, Brian P; Izquierdo, Denisse; Tsou, Meng-Fu Bryan

2016-07-02

Mitosis occurs efficiently, but when it is disturbed or delayed, p53-dependent cell death or senescence is often triggered after mitotic exit. To characterize this process, we conducted CRISPR-mediated loss-of-function screens using a cell-based assay in which mitosis is consistently disturbed by centrosome loss. We identified 53BP1 and USP28 as essential components acting upstream of p53, evoking p21-dependent cell cycle arrest in response not only to centrosome loss, but also to other distinct defects causing prolonged mitosis. Intriguingly, 53BP1 mediates p53 activation independently of its DNA repair activity, but requiring its interacting protein USP28 that can directly deubiquitinate p53 in vitro and ectopically stabilize p53 in vivo. Moreover, 53BP1 can transduce prolonged mitosis to cell cycle arrest independently of the spindle assembly checkpoint (SAC), suggesting that while SAC protects mitotic accuracy by slowing down mitosis, 53BP1 and USP28 function in parallel to select against disturbed or delayed mitosis, promoting mitotic efficiency.

Helicobacter pylori shows asymmetric and polar cell divisome assembly associated with DNA replisome.

PubMed

Kamran, Mohammad; Dubey, Priyanka; Verma, Vijay; Dasgupta, Santanu; Dhar, Suman K

2018-05-09

DNA replication and cell division are two fundamental processes in the life cycle of a cell. The majority of prokaryotic cells undergo division by means of binary fission in coordination with replication of the genome. Both processes, but especially their coordination, are poorly understood in Helicobacter pylori. Here, we studied the cell divisome assembly and the subsequent processes of membrane and peptidoglycan synthesis in the bacterium. To our surprise, we found the cell divisome assembly to be polar, which was well-corroborated by the asymmetric membrane and peptidoglycan synthesis at the poles. The divisome components showed its assembly to be synchronous with that of the replisome and the two remained associated throughout the cell cycle, demonstrating a tight coordination among chromosome replication, segregation and cell division in H. pylori. To our knowledge, this is the first report where both DNA replication and cell division along with their possible association have been demonstrated for this pathogenic bacterium. © 2018 Federation of European Biochemical Societies.

Predicting the ultimate potential of natural gas SOFC power cycles with CO2 capture - Part A: Methodology and reference cases

NASA Astrophysics Data System (ADS)

Campanari, Stefano; Mastropasqua, Luca; Gazzani, Matteo; Chiesa, Paolo; Romano, Matteo C.

2016-08-01

Driven by the search for the highest theoretical efficiency, in the latest years several studies investigated the integration of high temperature fuel cells in natural gas fired power plants, where fuel cells are integrated with simple or modified Brayton cycles and/or with additional bottoming cycles, and CO2 can be separated via chemical or physical separation, oxy-combustion and cryogenic methods. Focusing on Solid Oxide Fuel Cells (SOFC) and following a comprehensive review and analysis of possible plant configurations, this work investigates their theoretical potential efficiency and proposes two ultra-high efficiency plant configurations based on advanced intermediate-temperature SOFCs integrated with a steam turbine or gas turbine cycle. The SOFC works at atmospheric or pressurized conditions and the resulting power plant exceeds 78% LHV efficiency without CO2 capture (as discussed in part A of the work) and 70% LHV efficiency with substantial CO2 capture (part B). The power plants are simulated at the 100 MW scale with a complete set of realistic assumptions about fuel cell (FC) performance, plant components and auxiliaries, presenting detailed energy and material balances together with a second law analysis.

Riboflavin Depletion Promotes Tumorigenesis in HEK293T and NIH3T3 Cells by Sustaining Cell Proliferation and Regulating Cell Cycle-Related Gene Transcription.

PubMed

Long, Lin; He, Jian-Zhong; Chen, Ye; Xu, Xiu-E; Liao, Lian-Di; Xie, Yang-Min; Li, En-Min; Xu, Li-Yan

2018-05-07

Riboflavin is an essential component of the human diet and its derivative cofactors play an established role in oxidative metabolism. Riboflavin deficiency has been linked with various human diseases. The objective of this study was to identify whether riboflavin depletion promotes tumorigenesis. HEK293T and NIH3T3 cells were cultured in riboflavin-deficient or riboflavin-sufficient medium and passaged every 48 h. Cells were collected every 5 generations and plate colony formation assays were performed to observe cell proliferation. Subcutaneous tumorigenicity assays in NU/NU mice were used to observe tumorigenicity of riboflavin-depleted HEK293T cells. Mechanistically, gene expression profiling and gene ontology analysis were used to identify abnormally expressed genes induced by riboflavin depletion. Western blot analyses, cell cycle analyses, and chromatin immunoprecipitation were used to validate the expression of cell cycle-related genes. Plate colony formation of NIH3T3 and HEK293T cell lines was enhanced >2-fold when cultured in riboflavin-deficient medium for 10-20 generations. Moreover, we observed enhanced subcutaneous tumorigenicity in NU/NU mice following injection of riboflavin-depleted compared with normal HEK293T cells (55.6% compared with 0.0% tumor formation, respectively). Gene expression profiling and gene ontology analysis revealed that riboflavin depletion induced the expression of cell cycle-related genes. Validation experiments also found that riboflavin depletion decreased p21 and p27 protein levels by ∼20%, and increased cell cycle-related and expression-elevated protein in tumor (CREPT) protein expression >2-fold, resulting in cyclin D1 and CDK4 levels being increased ∼1.5-fold, and cell cycle acceleration. We also observed that riboflavin depletion decreased intracellular riboflavin levels by 20% and upregulated expression of riboflavin transporter genes, particularly SLC52A3, and that the changes in CREPT and SLC52A3 correlated with specific epigenetic changes in their promoters in riboflavin-depleted HEK293T cells. Riboflavin depletion contributes to HEK293T and NIH3T3 cell tumorigenesis and may be a risk factor for tumor development.

HPV-16 virions can remain infectious for 2 weeks on senescent cells but require cell cycle re-activation to allow virus entry.

PubMed

Broniarczyk, Justyna; Ring, Nadja; Massimi, Paola; Giacca, Mauro; Banks, Lawrence

2018-01-16

Successful infection with Human Papillomaviruses requires mitosis, when incoming viral genomes gain access to nuclear components. However, very little is known about how long HPV particles can remain infectious in non-dividing cells or in which cellular compartments these viruses may reside. To investigate these questions we have used BJ cells as a reversible model of senescence and show that HPV-16 can only infect early-passage proliferating cells. Late-passage senescent cells are resistant to HPV infection, but this can be reversed by inducing cell cycle re-entry with a p53 siRNA. In senescent cells we find that efficient virus entry can be attained upon cell cycle re-entry 16 days after infection, demonstrating that HPV can persist for 2 weeks prior to induction of mitosis. However, exposing cells to anti-HPV-16 L1 neutralising antibody blocks infection at these late time points, suggesting that the virions reside near the cell surface. Indeed, immunofluorescence analysis shows that virions accumulate on the cell surface of senescent cells and only enter endocytic vesicles upon stimulation with p53 siRNA. These results demonstrate that HPV-16 virions can remain viable on a non-dividing cell for extended periods of time, but are nonetheless vulnerable to antibody-induced neutralisation throughout.

The Deadbeat Paternal Effect of Uncapped Sperm Telomeres on Cell Cycle Progression and Chromosome Behavior in Drosophila melanogaster

PubMed Central

Yamaki, Takuo; Yasuda, Glenn K.; Wakimoto, Barbara T.

2016-01-01

Telomere-capping complexes (TCCs) protect the ends of linear chromosomes from illegitimate repair and end-to-end fusions and are required for genome stability. The identity and assembly of TCC components have been extensively studied, but whether TCCs require active maintenance in nondividing cells remains an open question. Here we show that Drosophila melanogaster requires Deadbeat (Ddbt), a sperm nuclear basic protein (SNBP) that is recruited to the telomere by the TCC and is required for TCC maintenance during genome-wide chromatin remodeling, which transforms spermatids to mature sperm. Ddbt-deficient males produce sperm lacking TCCs. Their offspring delay the initiation of anaphase as early as cycle 1 but progress through the first two cycles. Persistence of uncapped paternal chromosomes induces arrest at or around cycle 3. This early arrest can be rescued by selective elimination of paternal chromosomes and production of gynogenetic haploid or haploid mosaics. Progression past cycle 3 can also occur if embryos have reduced levels of the maternally provided checkpoint kinase Chk2. The findings provide insights into how telomere integrity affects the regulation of the earliest embryonic cell cycles. They also suggest that other SNBPs, including those in humans, may have analogous roles and manifest as paternal effects on embryo quality. PMID:27029731

Human rpL3 induces G₁/S arrest or apoptosis by modulating p21waf1/cip1 levels in a p53-independent manner

PubMed Central

Russo, Annapina; Esposito, Davide; Catillo, Morena; Pietropaolo, Concetta; Crescenzi, Elvira; Russo, Giulia

2013-01-01

It is now largely accepted that ribosomal proteins may be implicated in a variety of biological functions besides that of components of the translation machinery. Many evidences show that a subset of ribosomal proteins are involved in the regulation of the cell cycle and apoptosis through modulation of p53 activity. In addition, p53-independent mechanisms of cell cycle arrest in response to alterations of ribosomal proteins availability have been described. Here, we identify human rpL3 as a new regulator of cell cycle and apoptosis through positive regulation of p21 expression in a p53-independent system. We demonstrate that the rpL3-mediated p21 upregulation requires the specific interaction between rpL3 and Sp1. Furthermore, in our experimental system, p21 overexpression leads to a dual outcome, activating the G₁/S arrest of the cell cycle or the apoptotic pathway through mitochondria, depending on its intracellular levels. It is noteworthy that depletion of p21 abrogates both effects. Taken together, our findings unravel a novel extraribosomal function of rpL3 and reinforce the proapoptotic role of p21 in addition to its widely reported ability as an inhibitor of cell proliferation. PMID:23255119

Knockdown of hTERT and concurrent treatment with interferon-gamma inhibited proliferation and invasion of human glioblastoma cell lines

PubMed Central

George, Joseph; Banik, Naren L.; Ray, Swapan K.

2011-01-01

Human telomerase reverse transcriptase (hTERT) is the catalytic component of telomerase that facilitates tumor cell invasion and proliferation. Telomerase and hTERT are remarkably upregulated in majority of cancers including glioblastoma. Interferon-gamma (IFN-γ) modulates several cellular activities including cell cycle and multiplication through transcriptional regulation. The present investigation was designed to unravel the molecular mechanisms of the inhibition of cell proliferation, migration, and invasion of human glioblastoma SNB-19 and LN-18 cell lines after knockdown of hTERT using a plasmid vector based siRNA and concurrent treatment with IFN-γ. We observed more than 80% inhibition of cell proliferation, migration, and invasion of both cell lines after the treatment with combination of hTERT siRNA and IFN-γ. Our studies also showed accumulation of apoptotic cells in subG1 phase and an increase in cell population in G0/G1 with a reduction in G2/M phase indicating cell cycle arrest in G0/G1 phase for apoptosis. Semiquantitative and real-time RT-PCR analyses demonstrated significant downregulation of c- Myc and upregulation of p21 Waf1 and p27 Kip1. Western blotting confirmed the downregulation of the molecules involved in cell proliferation, migration, and invasion and also showed upregulation of cell cycle inhibitors. In conclusion, our study demonstrated that knockdown of hTERT siRNA and concurrent treatment with IFN-γ effectively inhibited cell proliferation, migration, and invasion in glioblastoma cells through downregulation of the molecules involved in these processes and cell cycle inhibition. Therefore, the combination of hTERT siRNA and IFN-γ offers a potential therapeutic strategy for controlling growth of human glioblastoma cells. PMID:20394835

Histone phosphorylation: its role during cell cycle and centromere identity in plants.

PubMed

Zhang, B; Dong, Q; Su, H; Birchler, J A; Han, F

2014-01-01

As the main protein components of chromatin, histones can alter the structural/functional capabilities of chromatin by undergoing extensive post-translational modifications (PTMs) such as phosphorylation, methylation, acetylation, ubiquitination, sumoylation, and so on. These PTMs are thought to transmit signals from the chromatin to the cell machinery to regulate various processes. Histone phosphorylation is associated with chromosome condensation/segregation, activation of transcription, and DNA damage repair. In this review, we focus on how different histone phosphorylations mark for chromatin change during the cell cycle, the relationship between histone phosphorylation and functional centromeres, and the candidate kinases that trigger and the phosphatase or kinase inhibitors that alter histone phosphorylation. Finally, we review the crosstalk between different PTMs. © 2014 S. Karger AG, Basel.

[Membrane model of the regulation of proliferation: the theory and interpretation of an experiment].

PubMed

Volkov, E I

1983-04-01

The role of cell surface physical organization in the cell cycle regulation is analyzed within the framework of the earlier proposed theory (Chernavskii et al., 1982). Two models of cell surface are considered: hard-frame fluid-mosaic model (latticemosaic) and the fluid-mosaic one. The former deals with normal cells. The existence of integral carcasse or "frame" which is formed by the essential part of cross-linked membrane components and may have at least two different conformational states is hypothesized. The second model describes membranes of tumour cells. With the latter theory any mitogen (excluding the restoration of nutrient depletion) reduces the mechanical tensile strength of the frame and stimulates the general structural rearrangement of the plasma membrane. There are only two conformational transitions during the cell cycle which serve as signals for the beginning of S and M phases. If the values of tensile strength are great enough and therefore the conformational transitions are impossible, the cells pass into the resting (prereplicative--G01, or premitotical--G02) state. Three types of experiments are interpreted in the proposed theory: a) on differences in the action of growth factors on normal and tumour cell cycle, b) on the necessary condition for mitogenicity of lectins, c) on the stimulation of proliferation by mechanical deformation of cells.

HPV-type-specific response of cervical cancer cells to cisplatin after silencing replication licensing factor MCM4.

PubMed

Das, Mitali; Prasad, Shyam Babu; Yadav, Suresh Singh; Modi, Arusha; Singh, Sunita; Pradhan, Satyajit; Narayan, Gopeshwar

2015-12-01

Minichoromosome maintenance (MCM) proteins play key role in cell cycle progression by licensing DNA replication only once per cell cycle. These proteins are found to be overexpressed in cervical cancer cells. In this study, we depleted MCM4, one of the MCM 2-7 complex components by RNA interference (RNAi) in four cervical cancer cell lines. The four cell lines were selected on the basis of their human papillomavirus (HPV) infection: HPV16-positive SiHa, HPV18-positive ME-180, HPV16- and HPV18-positive CaSki, and HPV-negative C-33A. The MCM4-deficient cells irrespective of their HPV status grow for several generations and maintain regular cell cycle. We did not find any evidence of augmented response to a short-term (48 h) cisplatin treatment in these MCM4-deficient cells. However, MCM4-/HPV16+ SiHa cells cannot withstand a prolonged treatment (up to 5 days) of even a sublethal dosage of cisplatin. They show increased chromosomal instability compared to their control counterparts. On the other hand, MCM4-deficient CaSki cells (both HPV16+ and 18+) remain resistant to a prolonged exposure to cisplatin. Our study indicates that cervical cancer cells may be using excess MCMs as a backup for replicative stress; however, its regulatory mechanism is dependent on the HPV status of the cells.

Electron Microscopy of Ebola Virus-Infected Cells.

PubMed

Noda, Takeshi

2017-01-01

Ebola virus (EBOV) replicates in host cells, where both viral and cellular components show morphological changes during the process of viral replication from entry to budding. These steps in the replication cycle can be studied using electron microscopy (EM), including transmission electron microscopy (TEM) and scanning electron microscopy (SEM), which is one of the most useful methods for visualizing EBOV particles and EBOV-infected cells at the ultrastructural level. This chapter describes conventional methods for EM sample preparation of cultured cells infected with EBOV.

Targeted Zinc Delivery: A Novel Treatment for Prostate Cancer

DTIC Science & Technology

2010-06-01

aconitase, which normally functions to oxidize citrate during the Krebs cycle . Because citrate is a principle component of seminal fluid, prostate...tissue, likely due to the metabolic effects of zinc in the Krebs cycle . That is, because zinc inhibits m- aconitase, loss of zinc allows for greater...secretory cells do not complete the oxidation of citrate in the mitochondria and the zinc-mediated inhibition of m-aconitase is crucial for the

Dynamic Expression of the Translational Machinery during Bacillus subtilis Life Cycle at a Single Cell Level

PubMed Central

Rosenberg, Alex; Sinai, Lior; Smith, Yoav; Ben-Yehuda, Sigal

2012-01-01

The ability of bacteria to responsively regulate the expression of translation components is crucial for rapid adaptation to fluctuating environments. Utilizing Bacillus subtilis (B. subtilis) as a model organism, we followed the dynamics of the translational machinery at a single cell resolution during growth and differentiation. By comprehensive monitoring the activity of the major rrn promoters and ribosomal protein production, we revealed diverse dynamics between cells grown in rich and poor medium, with the most prominent dissimilarities exhibited during deep stationary phase. Further, the variability pattern of translational activity varied among the cells, being affected by nutrient availability. We have monitored for the first time translational dynamics during the developmental process of sporulation within the two distinct cellular compartments of forespore and mother-cell. Our study uncovers a transient forespore specific increase in expression of translational components. Finally, the contribution of each rrn promoter throughout the bacterium life cycle was found to be relatively constant, implying that differential expression is not the main purpose for the existence of multiple rrn genes. Instead, we propose that coordination of the rrn operons serves as a strategy to rapidly fine tune translational activities in a synchronized fashion to achieve an optimal translation level for a given condition. PMID:22848659

Time-Resolved Visualisation of Nearly-Native Influenza A Virus Progeny Ribonucleoproteins and Their Individual Components in Live Infected Cells

PubMed Central

Avilov, Sergiy; Magnus, Julie; Cusack, Stephen; Naffakh, Nadia

2016-01-01

Influenza viruses are a global health concern because of the permanent threat of novel emerging strains potentially capable of causing pandemics. Viral ribonucleoproteins (vRNPs) containing genomic RNA segments, nucleoprotein oligomers, and the viral polymerase, play a central role in the viral replication cycle. Our knowledge about critical events such as vRNP assembly and interactions with other viral and cellular proteins is poor and could be substantially improved by time lapse imaging of the infected cells. However, such studies are limited by the difficulty to achieve live-cell compatible labeling of active vRNPs. Previously we designed the first unimpaired recombinant influenza WSN-PB2-GFP11 virus allowing fluorescent labeling of the PB2 subunit of the viral polymerase (Avilov et al., J.Virol. 2012). Here, we simultaneously labeled the viral PB2 protein using the above-mentioned strategy, and virus-encoded progeny RNPs through spontaneous incorporation of transiently expressed NP-mCherry fusion proteins during RNP assembly in live infected cells. This dual labeling enabled us to visualize progeny vRNPs throughout the infection cycle and to characterize independently the mobility, oligomerization status and interactions of vRNP components in the nuclei of live infected cells. PMID:26978069

A review of polymer electrolyte membrane fuel cell durability test protocols

NASA Astrophysics Data System (ADS)

Yuan, Xiao-Zi; Li, Hui; Zhang, Shengsheng; Martin, Jonathan; Wang, Haijiang

Durability is one of the major barriers to polymer electrolyte membrane fuel cells (PEMFCs) being accepted as a commercially viable product. It is therefore important to understand their degradation phenomena and analyze degradation mechanisms from the component level to the cell and stack level so that novel component materials can be developed and novel designs for cells/stacks can be achieved to mitigate insufficient fuel cell durability. It is generally impractical and costly to operate a fuel cell under its normal conditions for several thousand hours, so accelerated test methods are preferred to facilitate rapid learning about key durability issues. Based on the US Department of Energy (DOE) and US Fuel Cell Council (USFCC) accelerated test protocols, as well as degradation tests performed by researchers and published in the literature, we review degradation test protocols at both component and cell/stack levels (driving cycles), aiming to gather the available information on accelerated test methods and degradation test protocols for PEMFCs, and thereby provide practitioners with a useful toolbox to study durability issues. These protocols help prevent the prolonged test periods and high costs associated with real lifetime tests, assess the performance and durability of PEMFC components, and ensure that the generated data can be compared.

Lithium sulfur batteries and electrolytes and sulfur cathodes thereof

DOEpatents

Visco, Steven J.; Goncharenko, Nikolay; Nimon, Vitaliy; Petrov, Alexei; Nimon, Yevgeniy S.; De Jonghe, Lutgard C.; Katz, Bruce D.; Loginova, Valentina

2017-05-23

Lithium sulfur battery cells that use water as an electrolyte solvent provide significant cost reductions. Electrolytes for the battery cells may include water solvent for maintaining electroactive sulfur species in solution during cell discharge and a sufficient amount of a cycle life-enhancing compound that facilitates charging at the cathode. The combination of these two components enhances one or more of the following cell attributes: energy density, power density and cycle life. For instance, in applications where cost per Watt-Hour (Wh) is paramount, such as grid storage and traction applications, the use of an aqueous electrolyte in combination with inexpensive sulfur as the cathode active material can be a key enabler for the utility and automotive industries, for example, providing a cost effective and compact solution for load leveling, electric vehicles and renewable energy storage. Sulfur cathodes, and methods of fabricating lithium sulfur cells, in particular for loading lithium sulfide into the cathode structures, provide further advantages.

Gene Expression Profiling in BRAF-Mutated Melanoma Reveals Patient Subgroups with Poor Outcomes to Vemurafenib That May Be Overcome by Cobimetinib Plus Vemurafenib.

PubMed

Wongchenko, Matthew J; McArthur, Grant A; Dréno, Brigitte; Larkin, James; Ascierto, Paolo A; Sosman, Jeffrey; Andries, Luc; Kockx, Mark; Hurst, Stephen D; Caro, Ivor; Rooney, Isabelle; Hegde, Priti S; Molinero, Luciana; Yue, Huibin; Chang, Ilsung; Amler, Lukas; Yan, Yibing; Ribas, Antoni

2017-09-01

Purpose: The association of tumor gene expression profiles with progression-free survival (PFS) outcomes in patients with BRAF V600 -mutated melanoma treated with vemurafenib or cobimetinib combined with vemurafenib was evaluated. Experimental Design: Gene expression of archival tumor samples from patients in four trials (BRIM-2, BRIM-3, BRIM-7, and coBRIM) was evaluated. Genes significantly associated with PFS ( P < 0.05) were identified by univariate Cox proportional hazards modeling, then subjected to unsupervised hierarchical clustering, principal component analysis, and recursive partitioning to develop optimized gene signatures. Results: Forty-six genes were identified as significantly associated with PFS in both BRIM-2 ( n = 63) and the vemurafenib arm of BRIM-3 ( n = 160). Two distinct signatures were identified: cell cycle and immune. Among vemurafenib-treated patients, the cell-cycle signature was associated with shortened PFS compared with the immune signature in the BRIM-2/BRIM-3 training set [hazard ratio (HR) 1.8; 95% confidence interval (CI), 1.3-2.6, P = 0.0001] and in the coBRIM validation set ( n = 101; HR, 1.6; 95% CI, 1.0-2.5; P = 0.08). The adverse impact of the cell-cycle signature on PFS was not observed in patients treated with cobimetinib combined with vemurafenib ( n = 99; HR, 1.1; 95% CI, 0.7-1.8; P = 0.66). Conclusions: In vemurafenib-treated patients, the cell-cycle gene signature was associated with shorter PFS. However, in cobimetinib combined with vemurafenib-treated patients, both cell cycle and immune signature subgroups had comparable PFS. Cobimetinib combined with vemurafenib may abrogate the adverse impact of the cell-cycle signature. Clin Cancer Res; 23(17); 5238-45. ©2017 AACR . ©2017 American Association for Cancer Research.

Mechanistic Aspects of Adenovirus Serotype 2 Inactivation with Free Chlorine ▿ †

PubMed Central

Page, Martin A.; Shisler, Joanna L.; Mariñas, Benito J.

2010-01-01

Free chlorine is an effective disinfectant for controlling adenoviruses in drinking water, but little is known about the underlying inactivation mechanisms. The objective of this study was to elucidate the molecular components of adenovirus type 2 (Ad2) targeted by free chlorine during the inactivation process. The effects of free chlorine treatment on several Ad2 molecular components and associated life cycle events were compared to its effect on the ability of adenovirus to complete its life cycle, i.e., viability. Free chlorine treatment of Ad2 virions did not impair their ability to interact with monoclonal antibodies specific for hexon and fiber proteins of the Ad2 capsid, as measured by enzyme-linked immunosorbent assays, nor did it impair their interaction with recombinant, purified Coxsackie-adenovirus receptor (CAR) proteins in vitro. Free chlorine-treated Ad2 virions also retained their ability to bind to CAR receptors on A549 cell monolayers, despite being unable to form plaques, suggesting that free chlorine inactivates Ad2 by inhibiting a postbinding event of the Ad2 life cycle. DNA isolated from Ad2 virions that had been inactivated by free chlorine was able to be amplified by PCR, indicating that genome damage was not the cause of inactivation. However, inactivated Ad2 virions were unable to express E1A viral proteins during infection of A549 host cells, as measured by using immunoblotting. Collectively, these results indicate that free chlorine inactivates adenovirus by damaging proteins that govern life cycle processes occurring after host cell attachment, such as endocytosis, endosomal lysis, or nuclear delivery. PMID:20305026

Evolution and the origin of the visual retinoid cycle in vertebrates.

PubMed

Kusakabe, Takehiro G; Takimoto, Noriko; Jin, Minghao; Tsuda, Motoyuki

2009-10-12

Absorption of a photon by visual pigments induces isomerization of 11-cis-retinaldehyde (RAL) chromophore to all-trans-RAL. Since the opsins lacking 11-cis-RAL lose light sensitivity, sustained vision requires continuous regeneration of 11-cis-RAL via the process called 'visual cycle'. Protostomes and vertebrates use essentially different machinery of visual pigment regeneration, and the origin and early evolution of the vertebrate visual cycle is an unsolved mystery. Here we compare visual retinoid cycles between different photoreceptors of vertebrates, including rods, cones and non-visual photoreceptors, as well as between vertebrates and invertebrates. The visual cycle systems in ascidians, the closest living relatives of vertebrates, show an intermediate state between vertebrates and non-chordate invertebrates. The ascidian larva may use retinochrome-like opsin as the major isomerase. The entire process of the visual cycle can occur inside the photoreceptor cells with distinct subcellular compartmentalization, although the visual cycle components are also present in surrounding non-photoreceptor cells. The adult ascidian probably uses RPE65 isomerase, and trans-to-cis isomerization may occur in distinct cellular compartments, which is similar to the vertebrate situation. The complete transition to the sophisticated retinoid cycle of vertebrates may have required acquisition of new genes, such as interphotoreceptor retinoid-binding protein, and functional evolution of the visual cycle genes.

Pediatric brain tumor cancer stem cells: cell cycle dynamics, DNA repair, and etoposide extrusion

PubMed Central

Hussein, Deema; Punjaruk, Wiyada; Storer, Lisa C.D.; Shaw, Lucy; Ottoman, Ramadan; Peet, Andrew; Miller, Suzanne; Bandopadhyay, Gagori; Heath, Rachel; Kumari, Rajendra; Bowman, Karen J.; Braker, Paul; Rahman, Ruman; Jones, George D.D.; Watson, Susan; Lowe, James; Kerr, Ian D.; Grundy, Richard G.; Coyle, Beth

2011-01-01

Reliable model systems are needed to elucidate the role cancer stem cells (CSCs) play in pediatric brain tumor drug resistance. The majority of studies to date have focused on clinically distinct adult tumors and restricted tumor types. Here, the CSC component of 7 newly established primary pediatric cell lines (2 ependymomas, 2 medulloblastomas, 2 gliomas, and a CNS primitive neuroectodermal tumor) was thoroughly characterized. Comparison of DNA copy number with the original corresponding tumor demonstrated that genomic changes present in the original tumor, typical of that particular tumor type, were retained in culture. In each case, the CSC component was approximately 3–4-fold enriched in neurosphere culture compared with monolayer culture, and a higher capacity for multilineage differentiation was observed for neurosphere-derived cells. DNA content profiles of neurosphere-derived cells expressing the CSC marker nestin demonstrated the presence of cells in all phases of the cell cycle, indicating that not all CSCs are quiescent. Furthermore, neurosphere-derived cells demonstrated an increased resistance to etoposide compared with monolayer-derived cells, having lower initial DNA damage, potentially due to a combination of increased drug extrusion by ATP-binding cassette multidrug transporters and enhanced rates of DNA repair. Finally, orthotopic xenograft models reflecting the tumor of origin were established from these cell lines. In summary, these cell lines and the approach taken provide a robust model system that can be used to develop our understanding of the biology of CSCs in pediatric brain tumors and other cancer types and to preclinically test therapeutic agents. PMID:20978004

Pediatric brain tumor cancer stem cells: cell cycle dynamics, DNA repair, and etoposide extrusion.

PubMed

Hussein, Deema; Punjaruk, Wiyada; Storer, Lisa C D; Shaw, Lucy; Othman, Ramadhan; Ottoman, Ramadan; Peet, Andrew; Miller, Suzanne; Bandopadhyay, Gagori; Heath, Rachel; Kumari, Rajendra; Bowman, Karen J; Braker, Paul; Rahman, Ruman; Jones, George D D; Watson, Susan; Lowe, James; Kerr, Ian D; Grundy, Richard G; Coyle, Beth

2011-01-01

Reliable model systems are needed to elucidate the role cancer stem cells (CSCs) play in pediatric brain tumor drug resistance. The majority of studies to date have focused on clinically distinct adult tumors and restricted tumor types. Here, the CSC component of 7 newly established primary pediatric cell lines (2 ependymomas, 2 medulloblastomas, 2 gliomas, and a CNS primitive neuroectodermal tumor) was thoroughly characterized. Comparison of DNA copy number with the original corresponding tumor demonstrated that genomic changes present in the original tumor, typical of that particular tumor type, were retained in culture. In each case, the CSC component was approximately 3-4-fold enriched in neurosphere culture compared with monolayer culture, and a higher capacity for multilineage differentiation was observed for neurosphere-derived cells. DNA content profiles of neurosphere-derived cells expressing the CSC marker nestin demonstrated the presence of cells in all phases of the cell cycle, indicating that not all CSCs are quiescent. Furthermore, neurosphere-derived cells demonstrated an increased resistance to etoposide compared with monolayer-derived cells, having lower initial DNA damage, potentially due to a combination of increased drug extrusion by ATP-binding cassette multidrug transporters and enhanced rates of DNA repair. Finally, orthotopic xenograft models reflecting the tumor of origin were established from these cell lines. In summary, these cell lines and the approach taken provide a robust model system that can be used to develop our understanding of the biology of CSCs in pediatric brain tumors and other cancer types and to preclinically test therapeutic agents.

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

PubMed Central

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

2016-01-01

Metazoan development demands not only precise cell fate differentiation but also accurate timing of cell division to ensure proper development. How cell divisions are temporally coordinated during development is poorly understood. Caenorhabditis elegans embryogenesis provides an excellent opportunity to study this coordination due to its invariant development and widespread division asynchronies. One of the most pronounced asynchronies is a significant delay of cell division in two endoderm progenitor cells, Ea and Ep, hereafter referred to as E2, relative to its cousins that mainly develop into mesoderm organs and tissues. To unravel the genetic control over the endoderm-specific E2 division timing, a total of 822 essential and conserved genes were knocked down using RNAi followed by quantification of cell cycle lengths using in toto imaging of C. elegans embryogenesis and automated lineage. Intriguingly, knockdown of numerous genes encoding the components of general transcription pathway or its regulatory factors leads to a significant reduction in the E2 cell cycle length but an increase in cell cycle length of the remaining cells, indicating a differential requirement of transcription for division timing between the two. Analysis of lineage-specific RNA-seq data demonstrates an earlier onset of transcription in endoderm than in other germ layers, the timing of which coincides with the birth of E2, supporting the notion that the endoderm-specific delay in E2 division timing demands robust zygotic transcription. The reduction in E2 cell cycle length is frequently associated with cell migration defect and gastrulation failure. The results suggest that a tissue-specific transcriptional activation is required to coordinate fate differentiation, division timing, and cell migration to ensure proper development. PMID:27056332

Comparative Analysis of Transcriptomes of Macrophage Revealing the Mechanism of the Immunoregulatory Activities of a Novel Polysaccharide Isolated from Boletus speciosus Frost.

PubMed

Ding, Xiang; Zhu, Hongqing; Hou, Yiling; Hou, Wanru; Zhang, Nan; Fu, Lei

2017-01-01

The mechanism of the immunoregulatory activities of polysaccharide is still not clear. Here, we performed the B-cell, T-cell, and macrophage cell proliferation, the cell cycle analysis of macrophage cells, sequenced the transcriptomes of control group macrophages, and Boletus speciosus Frost polysaccharide (BSF-1) group macrophages using Illumina sequencing technology to identify differentially expressed genes (DEGs) to determine the molecular mechanisms of immunomodulatory activity of BSF-1 in macrophages. These results suggested that BSF-1 could promote the proliferation of B-cell, T-cell, and macrophages, promote the proliferation of macrophage cells by abolishing cell cycle arrests in the G0/G1 phases, and promote cell cycle progression in S-phase and G2/M phase, which might induce cell division. A total of 12,498,414 and 11,840,624 bp paired-end reads were obtained for the control group and BSF-1 group, respectively, and they corresponded to a total size of 12.5 G bp and 11.8 G bp, respectively, after the low-quality reads and adapter sequences were removed. Approximately 81.83% of the total number of genes (8,257) were expressed reads per kilobase per million mapped reads (RPKM ≥1) and more than 1366 genes were highly expressed (RPKM >60) in the BSF-1 group. A gene ontology-enrichment analysis generated 13,042 assignments to cellular components, 13,094 assignments to biological processes, and 13,135 assignments to molecular functions. A Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis showed that the mitogen-activated protein kinase (MAPK) signaling pathways are significantly enriched for DEGs between the two cell groups. An analysis of transcriptome resources enabled us to examine gene expression profiles, verify differential gene expression, and select candidate signaling pathways as the mechanisms of the immunomodulatory activity of BSF-1. Based on the experimental data, we believe that the significant antitumor activities of BSF-1 in vivo mainly involve the MAPK signaling pathways. Boletus speciosus Frost-1 (BSF-1) could promote the proliferation of B-cell, T-cell, and macrophages, promote the proliferation of macrophage cells by abolishing cell cycle arrests in the G0/G1 phases, and promote cell cycle progression in S-phase and G2/M phase, which might induce cell divisionApproximately 81.83% of the total number of genes (8257) were expressed (reads per kilobase per million mapped reads [RPKM] =1) and more than 1366 genes were highly expressed (RPKM >60) in the BSF-1 groupA gene ontology-enrichment analysis generated 13,042 assignments to cellular components, 13,094 assignments to biological processes, and 13,135 assignments to molecular functionsA Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis showed that the mitogen-activated protein kinase signaling pathways are significantly enriched for DEGs between the two cell groups. Abbreviations used: BSF-1: Boletus speciosus Frost polysaccharide.

Automated assembling of single fuel cell units for use in a fuel cell stack

NASA Astrophysics Data System (ADS)

Jalba, C. K.; Muminovic, A.; Barz, C.; Nasui, V.

2017-05-01

The manufacturing of PEMFC stacks (POLYMER ELEKTROLYT MEMBRAN Fuel Cell) is nowadays still done by hand. Over hundreds of identical single components have to be placed accurate together for the construction of a fuel cell stack. Beside logistic problems, higher total costs and disadvantages in weight the high number of components produce a higher statistic interference because of faulty erection or material defects and summation of manufacturing tolerances. The saving of costs is about 20 - 25 %. Furthermore, the total weight of the fuel cells will be reduced because of a new sealing technology. Overall a one minute cycle time has to be aimed per cell at the manufacturing of these single components. The change of the existing sealing concept to a bonded sealing is one of the important requisites to get an automated manufacturing of single cell units. One of the important steps for an automated gluing process is the checking of the glue application by using of an image processing system. After bonding the single fuel cell the sealing and electrical function can be checked, so that only functional and high qualitative cells can get into further manufacturing processes.

F-box protein FBXL2 targets cyclin D2 for ubiquitination and degradation to inhibit leukemic cell proliferation

PubMed Central

Chen, Bill B.; Glasser, Jennifer R.; Coon, Tiffany A.; Zou, Chunbin; Miller, Hannah L.; Fenton, Moon; McDyer, John F.; Boyiadzis, Michael

2012-01-01

Hematologic maligancies exhibit a growth advantage by up-regulation of components within the molecular apparatus involved in cell-cycle progression. The SCF (Skip-Cullin1-F-box protein) E3 ligase family provides homeostatic feedback control of cell division by mediating ubiquitination and degradation of cell-cycle proteins. By screening several previously undescribed E3 ligase components, we describe the behavior of a relatively new SCF subunit, termed FBXL2, that ubiquitinates and destabilizes cyclin D2 protein leading to G0 phase arrest and apoptosis in leukemic and B-lymphoblastoid cell lines. FBXL2 expression was strongly suppressed, and yet cyclin D2 protein levels were robustly expressed in acute myelogenous leukemia (AML) and acute lymphoblastic leukemia (ALL) patient samples. Depletion of endogenous FBXL2 stabilized cyclin D2 levels, whereas ectopically expressed FBXL2 decreased cyclin D2 lifespan. FBXL2 did not bind a phosphodegron within its substrate, which is typical of other F-box proteins, but uniquely targeted a calmodulin-binding signature within cyclin D2 to facilitate its polyubiquitination. Calmodulin competes with the F-box protein for access to this motif where it bound and protected cyclin D2 from FBXL2. Calmodulin reversed FBXL2-induced G0 phase arrest and attenuated FBXL2-induced apoptosis of lymphoblastoid cells. These results suggest an antiproliferative effect of SCFFBXL2 in lymphoproliferative malignancies. PMID:22323446

Controlled initiation of chromosomal replication in Escherichia coli requires functional Hda protein.

PubMed

Camara, Johanna Eltz; Skarstad, Kirsten; Crooke, Elliott

2003-05-01

Regulatory inactivation of DnaA helps ensure that the Escherichia coli chromosome is replicated only once per cell cycle, through accelerated hydrolysis of active replication initiator ATP-DnaA to inactive ADP-DnaA. Analysis of deltahda strains revealed that the regulatory inactivation of DnaA component Hda is necessary for maintaining controlled initiation but not for cell growth or viability.

COP9 Signalosome Subunit Csn8 Is Involved in Maintaining Proper Duration of the G1 Phase*

PubMed Central

Liu, Cheng; Guo, Li-Quan; Menon, Suchithra; Jin, Dan; Pick, Elah; Wang, Xuejun; Deng, Xing Wang; Wei, Ning

2013-01-01

The COP9 signalosome (CSN) is a conserved protein complex known to be involved in developmental processes of eukaryotic organisms. Genetic disruption of a CSN gene causes arrest during early embryonic development in mice. The Csn8 subunit is the smallest and the least conserved subunit, being absent from the CSN complex of several fungal species. Nevertheless, Csn8 is an integral component of the CSN complex in higher eukaryotes, where it is essential for life. By characterizing the mouse embryonic fibroblasts (MEFs) that express Csn8 at a low level, we found that Csn8 plays an important role in maintaining the proper duration of the G1 phase of the cell cycle. A decreased level of Csn8, either in Csn8 hypomorphic MEFs or following siRNA-mediated knockdown in HeLa cells, accelerated cell growth rate. Csn8 hypomorphic MEFs exhibited a shortened G1 duration and affected expression of G1 regulators. In contrast to Csn8, down-regulation of Csn5 impaired cell proliferation. Csn5 proteins were found both as a component of the CSN complex and outside of CSN (Csn5-f), and the amount of Csn5-f relative to CSN was increased in the Csn8 hypomorphic cells. We conclude that CSN harbors both positive and negative regulators of the cell cycle and therefore is poised to influence the fate of a cell at the crossroad of cell division, differentiation, and senescence. PMID:23689509

DUBbing Cancer: Deubiquitylating Enzymes Involved in Epigenetics, DNA Damage and the Cell Cycle As Therapeutic Targets.

PubMed

Pinto-Fernandez, Adan; Kessler, Benedikt M

2016-01-01

Controlling cell proliferation is one of the hallmarks of cancer. A number of critical checkpoints ascertain progression through the different stages of the cell cycle, which can be aborted when perturbed, for instance by errors in DNA replication and repair. These molecular checkpoints are regulated by a number of proteins that need to be present at the right time and quantity. The ubiquitin system has emerged as a central player controlling the fate and function of such molecules such as cyclins, oncogenes and components of the DNA repair machinery. In particular, proteases that cleave ubiquitin chains, referred to as deubiquitylating enzymes (DUBs), have attracted recent attention due to their accessibility to modulation by small molecules. In this review, we describe recent evidence of the critical role of DUBs in aspects of cell cycle checkpoint control, associated DNA repair mechanisms and regulation of transcription, representing pathways altered in cancer. Therefore, DUBs involved in these processes emerge as potentially critical targets for the treatment of not only hematological, but potentially also solid tumors.

DUBbing Cancer: Deubiquitylating Enzymes Involved in Epigenetics, DNA Damage and the Cell Cycle As Therapeutic Targets

PubMed Central

Pinto-Fernandez, Adan; Kessler, Benedikt M.

2016-01-01

Controlling cell proliferation is one of the hallmarks of cancer. A number of critical checkpoints ascertain progression through the different stages of the cell cycle, which can be aborted when perturbed, for instance by errors in DNA replication and repair. These molecular checkpoints are regulated by a number of proteins that need to be present at the right time and quantity. The ubiquitin system has emerged as a central player controlling the fate and function of such molecules such as cyclins, oncogenes and components of the DNA repair machinery. In particular, proteases that cleave ubiquitin chains, referred to as deubiquitylating enzymes (DUBs), have attracted recent attention due to their accessibility to modulation by small molecules. In this review, we describe recent evidence of the critical role of DUBs in aspects of cell cycle checkpoint control, associated DNA repair mechanisms and regulation of transcription, representing pathways altered in cancer. Therefore, DUBs involved in these processes emerge as potentially critical targets for the treatment of not only hematological, but potentially also solid tumors. PMID:27516771

Hydrogen-Oxygen PEM Regenerative Fuel Cell Development at NASA Glenn Research Center

NASA Technical Reports Server (NTRS)

Bents, David J.; Scullin, Vincent J.; Chang, B. J.; Johnson, Donald W.; Garcia, Christopher P.; Jakupca, Ian J.

2006-01-01

The closed-cycle hydrogen-oxygen PEM regenerative fuel cell (RFC) at NASA Glenn Research Center has demonstrated multiple back to back contiguous cycles at rated power, and round trip efficiencies up to 52 percent. It is the first fully closed cycle regenerative fuel cell ever demonstrated (entire system is sealed: nothing enters or escapes the system other than electrical power and heat). During FY2006 the system has undergone numerous modifications and internal improvements aimed at reducing parasitic power, heat loss and noise signature, increasing its functionality as an unattended automated energy storage device, and in-service reliability. It also serves as testbed towards development of a 600 W-hr/kg flight configuration, through the successful demonstration of lightweight fuel cell and electrolyser stacks and supporting components. The RFC has demonstrated its potential as an energy storage device for aerospace solar power systems such as solar electric aircraft, lunar and planetary surface installations; any airless environment where minimum system weight is critical. Its development process continues on a path of risk reduction for the flight system NASA will eventually need for the manned lunar outpost.

Formononetin induces cell cycle arrest of human breast cancer cells via IGF1/PI3K/Akt pathways in vitro and in vivo.

PubMed

Chen, J; Zeng, J; Xin, M; Huang, W; Chen, X

2011-09-01

Formononetin is one of the main components of red clover plants, and is considered as a typical phytoestrogen. This study further investigated that formononetin inactivated IGF1/IGF1R-PI3K/Akt pathways and decreased cyclin D1 mRNA and protein expression in human breast cancer cells in vitro and in vivo. MCF-7 cells were treated with different concentrations of formononetin. The proliferation of the cells treated with formononetin was tested by MTT assay. The cell cycle in the treated cells was examined by flow cytometry. The levels of p-IGF-1 R, p-Akt, and cyclin D1 protein expression and cyclin D1 mRNA expression in the treated cells were determined by Western blot and RT-PCR, respectively. In addition, the antitumor activity of formononetin was evaluated in nude mice bearing orthotopic tumor implants. Compared with the control, formononetin inhibited the proliferation of MCF-7 cells and effectively induced cell cycle arrest. The levels of p-IGF-1 R, p-Akt, cyclin D1 protein expression, and cyclin D1 mRNA expression were also downregulated. On the other hand, formononetin also prevented the tumor growth of human breast cancer cells in nude mouse xenografts. These results show that formononetin causes cell cycle arrest at the G0/G1 phase by inactivating IGF1/IGF1R-PI3K/Akt pathways and decreasing cyclin D1 mRNA and protein expression, indicating the use of formononetin in the prevention of breast cancer carcinogenesis. Georg Thieme Verlag KG Stuttgart · New York.

Singlet oxygen generation as a major cause for parasitic reactions during cycling of aprotic lithium-oxygen batteries

NASA Astrophysics Data System (ADS)

Mahne, Nika; Schafzahl, Bettina; Leypold, Christian; Leypold, Mario; Grumm, Sandra; Leitgeb, Anita; Strohmeier, Gernot A.; Wilkening, Martin; Fontaine, Olivier; Kramer, Denis; Slugovc, Christian; Borisov, Sergey M.; Freunberger, Stefan A.

2017-03-01

Non-aqueous metal-oxygen batteries depend critically on the reversible formation/decomposition of metal oxides on cycling. Irreversible parasitic reactions cause poor rechargeability, efficiency, and cycle life, and have predominantly been ascribed to the reactivity of reduced oxygen species with cell components. These species, however, cannot fully explain the side reactions. Here we show that singlet oxygen forms at the cathode of a lithium-oxygen cell during discharge and from the onset of charge, and accounts for the majority of parasitic reaction products. The amount increases during discharge, early stages of charge, and charging at higher voltages, and is enhanced by the presence of trace water. Superoxide and peroxide appear to be involved in singlet oxygen generation. Singlet oxygen traps and quenchers can reduce parasitic reactions effectively. Awareness of the highly reactive singlet oxygen in non-aqueous metal-oxygen batteries gives a rationale for future research towards achieving highly reversible cell operation.

The Genetic Program of Pancreatic β-Cell Replication In Vivo.

PubMed

Klochendler, Agnes; Caspi, Inbal; Corem, Noa; Moran, Maya; Friedlich, Oriel; Elgavish, Sharona; Nevo, Yuval; Helman, Aharon; Glaser, Benjamin; Eden, Amir; Itzkovitz, Shalev; Dor, Yuval

2016-07-01

The molecular program underlying infrequent replication of pancreatic β-cells remains largely inaccessible. Using transgenic mice expressing green fluorescent protein in cycling cells, we sorted live, replicating β-cells and determined their transcriptome. Replicating β-cells upregulate hundreds of proliferation-related genes, along with many novel putative cell cycle components. Strikingly, genes involved in β-cell functions, namely, glucose sensing and insulin secretion, were repressed. Further studies using single-molecule RNA in situ hybridization revealed that in fact, replicating β-cells double the amount of RNA for most genes, but this upregulation excludes genes involved in β-cell function. These data suggest that the quiescence-proliferation transition involves global amplification of gene expression, except for a subset of tissue-specific genes, which are "left behind" and whose relative mRNA amount decreases. Our work provides a unique resource for the study of replicating β-cells in vivo. © 2016 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.

Choline availability modulates human neuroblastoma cell proliferation and alters the methylation of the promoter region of the cyclin-dependent kinase inhibitor 3 gene

PubMed Central

Niculescu, Mihai D.; Yamamuro, Yutaka; Zeisel, Steven H.

2006-01-01

Choline is an important methyl donor and a component of membrane phospholipids. In this study, we tested the hypothesis that choline availability can modulate cell proliferation and the methylation of genes that regulate cell cycling. In several other model systems, hypomethylation of cytosine bases that are followed by a guanosine (CpG) sites in the promoter region of a gene is associated with increased gene expression. We found that in choline-deficient IMR-32 neuroblastoma cells, the promoter of the cyclin-dependent kinase inhibitor 3 gene (CDKN3) was hypomethylated. This change was associated with increased expression of CDKN3 and increased levels of its gene product, kinase-associated phosphatase (KAP), which inhibits the G1/S transition of the cell cycle by dephosphorylating cyclin-dependent kinases. Choline deficiency also reduced global DNA methylation. The percentage of cells that accumulated bromodeoxyuridine (proportional to cell proliferation) was 1.8 times lower in the choline-deficient cells than in the control cells. Phosphorylated retinoblastoma (p110) levels were 3 times lower in the choline-deficient cells than in control cells. These findings suggest that the mechanism whereby choline deficiency inhibits cell proliferation involves hypomethylation of key genes regulating cell cycling. This may be a mechanism for our previously reported observation that stem cell proliferation in hippocampus neuroepithelium is decreased in choline-deficient rat and mouse fetuses. PMID:15147518

The Centrosome and Its Duplication Cycle

PubMed Central

Fu, Jingyan; Hagan, Iain M.; Glover, David M.

2015-01-01

The centrosome was discovered in the late 19th century when mitosis was first described. Long recognized as a key organelle of the spindle pole, its core component, the centriole, was realized more than 50 or so years later also to comprise the basal body of the cilium. Here, we chart the more recent acquisition of a molecular understanding of centrosome structure and function. The strategies for gaining such knowledge were quickly developed in the yeasts to decipher the structure and function of their distinctive spindle pole bodies. Only within the past decade have studies with model eukaryotes and cultured cells brought a similar degree of sophistication to our understanding of the centrosome duplication cycle and the multiple roles of this organelle and its component parts in cell division and signaling. Now as we begin to understand these functions in the context of development, the way is being opened up for studies of the roles of centrosomes in human disease. PMID:25646378

Mediator can regulate mitotic entry and direct periodic transcription in fission yeast.

PubMed

Banyai, Gabor; Lopez, Marcela Davila; Szilagyi, Zsolt; Gustafsson, Claes M

2014-11-01

Cdk8 is required for correct timing of mitotic progression in fission yeast. How the activity of Cdk8 is regulated is unclear, since the kinase is not activated by T-loop phosphorylation and its partner, CycC, does not oscillate. Cdk8 is, however, a component of the multiprotein Mediator complex, a conserved coregulator of eukaryotic transcription that is connected to a number of intracellular signaling pathways. We demonstrate here that other Mediator components regulate the activity of Cdk8 in vivo and thereby direct the timing of mitotic entry. Deletion of Mediator components Med12 and Med13 leads to higher cellular Cdk8 protein levels, premature phosphorylation of the Cdk8 target Fkh2, and earlier entry into mitosis. We also demonstrate that Mediator is recruited to clusters of mitotic genes in a periodic fashion and that the complex is required for the transcription of these genes. We suggest that Mediator functions as a hub for coordinated regulation of mitotic progression and cell cycle-dependent transcription. The many signaling pathways and activator proteins shown to function via Mediator may influence the timing of these cell cycle events. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Cibotium barometz polysaccharides stimulate chondrocyte proliferation in vitro by promoting G1/S cell cycle transition

PubMed Central

Fu, Changlong; Zheng, Chunsong; Lin, Jie; Ye, Jinxia; Mei, Yangyang; Pan, Caibin; Wu, Guangwen; Li, Xihai; Ye, Hongzhi; Liu, Xianxiang

2017-01-01

Cibotium barometz polysaccharides (CBPS) are one of the most important bioactive components extracted from the Cibotium barometz plant, which belongs to the Dicksoniaceae family. It has been widely used for the treatment of orthopedic diseases in traditional Chinese medicine. However, the molecular mechanisms behind the therapeutic effects of CBPS remain to be clarified. In the present study, the concentration of CBPS was detected by phenol-vitriol colorimetry. Furthermore, the effects stimulated by CBPS on the viability and G1/S cell cycle transition in primary chondrocytes from Sprague-Dawley rats were investigated. A cell viability assay demonstrated that chondrocyte proliferation may be enhanced by CBPS in a dose- and time-dependent manner. The mechanism underlying the promotion of chondrocyte cell cycle was suggested to involve the stimulation of G1 to S phase transition. To further confirm the results, reverse transcription-quantitative polymerase chain reaction and western blot analyses were used to detect the expression of mRNA and protein levels of cyclin D1, cyclin-dependent kinase 4 and retinoblastoma protein. The results suggested that CBPS may stimulate chondrocyte proliferation via promoting G1/S cell cycle transition. Since osteoarthritis is characterized by deficient proliferation in chondrocytes, the present study indicates that CBPS may potentially serve as a novel method for the treatment of osteoarthritis. PMID:28358416

13-cis Retinoic acid induces apoptosis and cell cycle arrest in human SEB-1 sebocytes.

PubMed

Nelson, Amanda M; Gilliland, Kathryn L; Cong, Zhaoyuan; Thiboutot, Diane M

2006-10-01

Isotretinoin (13-cis retinoic acid (13-cis RA)) is the most potent inhibitor of sebum production, a key component in the pathophysiology of acne, yet its mechanism of action remains largely unknown. The effects of 13-cis RA, 9-cis retinoic acid (9-cis RA), and all-trans retinoic acid (ATRA) on cell proliferation, apoptosis, and cell cycle proteins were examined in SEB-1 sebocytes and keratinocytes. 13-cis RA causes significant dose-dependent and time-dependent decreases in viable SEB-1 sebocytes. A portion of this decrease can be attributed to cell cycle arrest as evidenced by decreased DNA synthesis, increased p21 protein expression, and decreased cyclin D1. Although not previously demonstrated in sebocytes, we report that 13-cis RA induces apoptosis in SEB-1 sebocytes as shown by increased Annexin V-FITC staining, increased TUNEL staining, and increased cleaved caspase 3 protein. Furthermore, the ability of 13-cis RA to induce apoptosis cannot be recapitulated by 9-cis RA or ATRA, and it is not inhibited by the presence of a retinoid acid receptor (RAR) pan-antagonist AGN 193109. Taken together these data indicate that 13-cis RA causes cell cycle arrest and induces apoptosis in SEB-1 sebocytes by a RAR-independent mechanism, which contributes to its sebosuppressive effect and the resolution of acne.

A systematic analysis of the PARP protein family identifies new functions critical for cell physiology

PubMed Central

Vyas, Sejal; Chesarone-Cataldo, Melissa; Todorova, Tanya; Huang, Yun-Han; Chang, Paul

2013-01-01

The poly(ADP-ribose) polymerase (PARP) family of proteins use NAD+ as their substrate to modify acceptor proteins with adenosine diphosphate-ribose (ADPr) modifications. The function of most PARPs under physiological conditions is unknown. Here, to better understand this protein family, we systematically analyze the cell cycle localization of each PARP and of poly(ADP-ribose), a product of PARP activity, then identify the knock-down phenotype of each protein and perform secondary assays to elucidate function. We show that most PARPs are cytoplasmic, identify cell cycle differences in the ratio of nuclear to cytoplasmic poly(ADP-ribose), and identify four phenotypic classes of PARP function. These include the regulation of membrane structures, cell viability, cell division, and the actin cytoskeleton. Further analysis of PARP14 shows that it is a component of focal adhesion complexes required for proper cell motility and focal adhesion function. In total, we show that PARP proteins are critical regulators of eukaryotic physiology. PMID:23917125

GABP transcription factor is required for development of chronic myelogenous leukemia via its control of PRKD2.

PubMed

Yang, Zhong-Fa; Zhang, Haojian; Ma, Leyuan; Peng, Cong; Chen, Yaoyu; Wang, Junling; Green, Michael R; Li, Shaoguang; Rosmarin, Alan G

2013-02-05

Hematopoietic stem cells (HSCs) are the source of all blood lineages, and HSCs must balance quiescence, self-renewal, and differentiation to meet lifelong needs for blood cell development. Transformation of HSCs by the breakpoint cluster region-ABL tyrosine kinase (BCR-ABL) oncogene causes chronic myelogenous leukemia (CML). The E-twenty six (ets) transcription factor GA binding protein (GABP) is a tetrameric transcription factor complex that contains GABPα and GABPβ proteins. Deletion in bone marrow of Gabpa, the gene that encodes the DNA-binding component, caused cell cycle arrest in HSCs and profound loss of hematopoietic progenitor cells. Loss of Gabpα prevented development of CML, although mice continued to generate BCR-ABL-expressing Gabpα-null cells for months that were serially transplantable and contributed to all lineages in secondary recipients. A bioinformatic screen identified the serine-threonine kinase protein kinase D2 (PRKD2) as a potential effector of GABP in HSCs. Prkd2 expression was markedly reduced in Gabpα-null HSCs and progenitor cells. Reduced expression of PRKD2 or pharmacologic inhibition decreased cell cycling, and PRKD2 rescued growth of Gabpα-null BCR-ABL-expressing cells. Thus, GABP is required for HSC cell cycle entry and CML development through its control of PRKD2. This offers a potential therapeutic target in leukemia.

Transient groundwater dynamics in a coastal aquifer: The effects of tides, the lunar cycle, and the beach profile

NASA Astrophysics Data System (ADS)

Abarca, Elena; Karam, Hanan; Hemond, Harold F.; Harvey, Charles F.

2013-05-01

Detailed field measurements are combined with a numerical modeling to characterize the groundwater dynamics beneath the discharge zone at Waquoit Bay, Massachusetts. Groundwater salinity values revealed a saline circulation cell that overlaid the discharging freshwater and grew and disappeared with the lunar cycle. The cell was initiated by a greater bay water infiltration during the new moon when high tides overtopped the mean high-tide mark, flooding the flatter beach berm and inundating a larger area of the beach. The dynamics of this cell were further characterized by a tracer test and by constructing a density-dependent flow model constrained to salinity and head data. The numerical model captured the growing and diminishing behavior of the circulation cell and provided the estimates of freshwater and saline water fluxes and travel times. Furthermore, the model enabled quantification of the relationship between the characteristics of the observed tidal cycle (maximum, minimum, and mean tidal elevations) and the different components of the groundwater circulation (freshwater discharge, intertidal saline cycling, and deep saline cycling). We found that (1) recharge to the intertidal saline cell is largely controlled by the high-tide elevation; (2) freshwater discharge is positively correlated to the low-tide elevation, whereas deep saline discharge from below the discharging freshwater is negatively correlated to the low-tide elevation. So, when the low-tide elevation is relatively high, more freshwater discharges and less deep saltwater discharges. In contrast when low tides are very low, less freshwater discharges and more deep salt water discharges; (3) offshore inflow of saline water is largely insensitive to tides and the lunar cycle.

Phytotoxicity and Cytotoxicity of Essential Oil from Leaves of Plectranthus amboinicus, Carvacrol, and Thymol in Plant Bioassays.

PubMed

Pinheiro, Patrícia Fontes; Costa, Adilson Vidal; Alves, Thammyres de Assis; Galter, Iasmini Nicoli; Pinheiro, Carlos Alexandre; Pereira, Alexandre Fontes; Oliveira, Carlos Magno Ramos; Fontes, Milene Miranda Praça

2015-10-21

The essential oil of Plectranthus amboinicus and its chemotypes, carvacrol and thymol, were evaluated on the germination and root and aerial growth of Lactuca sativa and Sorghum bicolor and in acting on the cell cycle of meristematic root cells of L. sativa. The main component found in the oil by analysis in gas chromatography-mass spectrometry and gas chromatography flame ionization detection was carvacrol (88.61% in area). At a concentration of 0.120% (w v(-1)), the oil and its chemotypes retarded or inhibited the germination and decreased root and aerial growth in monocot and dicot species used in the bioassays. In addition, all substances caused changes in the cell cycle of the meristematic cells of L. sativa, with chromosomal alterations occurring from the 0.015% (w v(-1)) concentration. The essential oil of P. amboinicus, carvacrol, and thymol have potential for use as bioherbicides.

Effects of water stress on photosynthetic electron transport, photophosphorylation, and metabolite levels of Xanthium strumarium mesophyll cells.

PubMed

Sharkey, T D; Badger, M R

1982-12-01

Several component processes of photosynthesis were measured in osmotically stressed mesophyll cells of Xanthium strumarium L. The ribulose-1,5-bisphosphate regeneration capacity was reduced by water stress. Photophoshorylation was sensitive to water stress but photosynthetic electron transport was unaffected by water potentials down to-40 bar (-4 MPa). The concentrations of several intermediates of the photosynthetic carbon-reduction cycle remained relatively constant and did not indicate that ATP supply was limiting photosynthesis in the water-stressed cells.

Automatic digital image analysis for identification of mitotic cells in synchronous mammalian cell cultures.

PubMed

Eccles, B A; Klevecz, R R

1986-06-01

Mitotic frequency in a synchronous culture of mammalian cells was determined fully automatically and in real time using low-intensity phase-contrast microscopy and a newvicon video camera connected to an EyeCom III image processor. Image samples, at a frequency of one per minute for 50 hours, were analyzed by first extracting the high-frequency picture components, then thresholding and probing for annular objects indicative of putative mitotic cells. Both the extraction of high-frequency components and the recognition of rings of varying radii and discontinuities employed novel algorithms. Spatial and temporal relationships between annuli were examined to discern the occurrences of mitoses, and such events were recorded in a computer data file. At present, the automatic analysis is suited for random cell proliferation rate measurements or cell cycle studies. The automatic identification of mitotic cells as described here provides a measure of the average proliferative activity of the cell population as a whole and eliminates more than eight hours of manual review per time-lapse video recording.

Hypericin-mediated photocytotoxic effect on HT-29 adenocarcinoma cells is reduced by light fractionation with longer dark pause between two unequal light doses.

PubMed

Sacková, Veronika; Kuliková, Lucia; Mikes, Jaromír; Kleban, Ján; Fedorocko, Peter

2005-01-01

The present study demonstrates the in vitro effect of hypericin-mediated PDT with fractionated light delivery. Cells were photosensitized with unequal light fractions separated by dark intervals (1 or 6 h). We compared the changes in viability, cell number, survival, apoptosis and cell cycle on HT-29 cells irradiated with a single light dose (12 J/cm(2)) to the fractionated light delivery (1 + 11 J/cm(2)) 24 and 48 h after photodynamic treatment. We found that a fractionated light regime with a longer dark period resulted in a decrease of hypericin cytotoxicity. Both cell number and survival were higher after light sensitization with a 6-h dark interval. DNA fragmentation occurred after a single light-dose application, but in contrast no apoptotic DNA formation was detected with a 6-h dark pause. After fractionation the percentage of cells in the G1 phase of the cell cycle was increased, while the proportion of cells in the G2 phase decreased as compared to a single light-dose application, i.e. both percentage of cells in the G1 and G2 phase of the cell cycle were near control levels. We presume that the longer dark interval after the irradiation of cells by first light dose makes them resistant to the effect of the second illumination. These findings confirm that the light application scheme together with other photodynamic protocol components is crucial for the photocytotoxicity of hypericin.

Quality of life, symptom status and physical performance in patients with advanced non-small cell lung cancer undergoing chemotherapy: an exploratory analysis of secondary data.

PubMed

Shallwani, Shirin M; Simmonds, Maureen J; Kasymjanova, Goulnar; Spahija, Jadranka

2016-09-01

Our objectives were: (a) to identify predictors of change in health-related quality of life (HRQOL) in patients with advanced non-small cell lung cancer (NSCLC) undergoing chemotherapy; and (b) to characterize symptom status, nutritional status, physical performance and HRQOL in this population and to estimate the extent to which these variables change following two cycles of chemotherapy. A secondary analysis of a longitudinal observational study of 47 patients (24 men and 23 women) with newly diagnosed advanced NSCLC receiving two cycles of first-line chemotherapy was performed. Primary outcomes were changes in HRQOL (physical and mental component summaries (PCS and MCS) of the 36-item Short-Form Health Survey (SF-36)). Predictors in the models included pre-chemotherapy patient-reported symptoms (Schwartz Cancer Fatigue Scale (SCFS) and Lung Cancer Subscale), nutritional screening (Patient-Generated Subjective Global Assessment) and physical performance measures (6-min Walk Test (6MWT), one-minute chair rise test and grip strength). Mean SF-36 PCS score, 6MWT distance and grip strength declined following two cycles of chemotherapy (p<0.05). Multiple linear regression modelling revealed pre-chemotherapy SCFS score and 6MWT distance as the strongest predictors of change in the mental component of HRQOL accounting for 13% and 9% of the variance, respectively. No significant predictors were found for change in the physical component of HRQOL. Pre-chemotherapy 6MWT distance and fatigue severity predicted change in the mental component of HRQOL in patients with advanced NSCLC undergoing chemotherapy, while physical performance declined during treatment. Clinical management of these factors may be useful for HRQOL optimization in this population. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

The Proteomic Profile of Deleted in Breast Cancer 1 (DBC1) Interactions Points to a Multifaceted Regulation of Gene Expression*

PubMed Central

Giguère, Sophie S. B.; Guise, Amanda J.; Jean Beltran, Pierre M.; Joshi, Preeti M.; Greco, Todd M.; Quach, Olivia L.; Kong, Jeffery; Cristea, Ileana M.

2016-01-01

Deleted in breast cancer 1 (DBC1) has emerged as an important regulator of multiple cellular processes, ranging from gene expression to cell cycle progression. DBC1 has been linked to tumorigenesis both as an inhibitor of histone deacetylases, HDAC3 and sirtuin 1, and as a transcriptional cofactor for nuclear hormone receptors. However, despite mounting interest in DBC1, relatively little is known about the range of its interacting partners and the scope of its functions. Here, we carried out a functional proteomics-based investigation of DBC1 interactions in two relevant cell types, T cells and kidney cells. Microscopy, molecular biology, biochemistry, and mass spectrometry studies allowed us to assess DBC1 mRNA and protein levels, localization, phosphorylation status, and protein interaction networks. The comparison of DBC1 interactions in these cell types revealed conserved regulatory roles for DBC1 in gene expression, chromatin organization and modification, and cell cycle progression. Interestingly, we observe previously unrecognized DBC1 interactions with proteins encoded by cancer-associated genes. Among these interactions are five components of the SWI/SNF complex, the most frequently mutated chromatin remodeling complex in human cancers. Additionally, we identified a DBC1 interaction with TBL1XR1, a component of the NCoR complex, which we validated by reciprocal isolation. Strikingly, we discovered that DBC1 associates with proteins that regulate the circadian cycle, including DDX5, DHX9, and SFPQ. We validated this interaction by colocalization and reciprocal isolation. Functional assessment of this association demonstrated that DBC1 protein levels are important for regulating CLOCK and BMAL1 protein oscillations in synchronized T cells. Our results suggest that DBC1 is integral to the maintenance of the circadian molecular clock. Furthermore, the identified interactions provide a valuable resource for the exploration of pathways involved in DBC1-associated tumorigenesis. PMID:26657080

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

PubMed Central

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

2013-01-01

Growth and cell division in rod-shaped bacteria have been primarily studied in species that grow predominantly by peptidoglycan (PG) synthesis along the length of the cell. Rhizobiales species, however, predominantly grow by PG synthesis at a single pole. Here we characterize the dynamic localization of several Agrobacterium tumefaciens components during the cell cycle. First, the lipophilic dye FM 4-64 predominantly stains the outer membranes of old poles versus growing poles. In cells about to divide, however, both poles are equally labeled with FM 4-64, but the constriction site is not. Second, the cell-division protein FtsA alternates from unipolar foci in the shortest cells to unipolar and midcell localization in cells of intermediate length, to strictly midcell localization in the longest cells undergoing septation. Third, the cell division protein FtsZ localizes in a cell-cycle pattern similar to, but more complex than, FtsA. Finally, because PG synthesis is spatially and temporally regulated during the cell cycle, we treated cells with sublethal concentrations of carbenicillin (Cb) to assess the role of penicillin-binding proteins in growth and cell division. Cb-treated cells formed midcell circumferential bulges, suggesting that interrupted PG synthesis destabilizes the septum. Midcell bulges contained bands or foci of FtsA-GFP and FtsZ-GFP and no FM 4-64 label, as in untreated cells. There were no abnormal morphologies at the growth poles in Cb-treated cells, suggesting unipolar growth uses Cb-insensitive PG synthesis enzymes. PMID:23674672

Panaxadiol, a purified ginseng component, enhances the anti-cancer effects of 5-fluorouracil in human colorectal cancer cells.

PubMed

Li, Xiao-Li; Wang, Chong-Zhi; Mehendale, Sangeeta R; Sun, Shi; Wang, Qi; Yuan, Chun-Su

2009-11-01

Colorectal cancer is a major cause of morbidity and mortality for cancer worldwide. Although 5-fluorouracil (5-FU) is one of the most widely used chemotherapeutic agents in first-line therapy for colorectal cancer, serious side effects limit its clinical usefulness. Panaxadiol (PD) is the purified sapogenin of ginseng saponins, which exhibit anti-tumor activity. In this study, we investigated the possible synergistic anti-cancer effects of PD and 5-FU on a human colorectal cancer cell line, HCT-116. Cell viability was evaluated by an MTS cell proliferation assay. Morphological observation was performed by crystal violet cell viability staining assay. Cell cycle distribution and apoptotic effects were analyzed by flow cytometry after staining with PI/RNase or Annexin V/PI. Cell growth was markedly suppressed in HCT-116 cells treated by 5-FU (20-100 microM) for 24 or 48 h with time-dependent effects. The significant suppression on HCT-116 cell proliferation was observed after treatment with PD (25 microM) for 24 and 48 h. Panaxadiol (25 microM) markedly (P < 0.05) enhanced the anti-proliferative effects of 5-FU (5, 10, 20 microM) on HCT-116 cells compared to single treatment of 5-FU for 24 and 48 h. Flow cytometric analysis on DNA indicated that PD and 5-FU selectively arrested cell cycle progression in the G1 phase and S phase (P < 0.01), respectively, compared to the control condition. Combination use of 5-FU with PD significantly (P < 0.001) increased cell cycle arrest in the S phase compared to that treated by 5-FU alone. The combination of 5-FU and PD significantly enhanced the percentage of apoptotic cells when compared with the corresponding cell groups treated by 5-FU alone (P < 0.001). Panaxadiol enhanced the anti-cancer effects of 5-FU on human colorectal cancer cells through the regulation of cell cycle transition and the induction of apoptotic cells.

New preparation method of {beta}{double_prime}-alumina and application for AMTEC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nishi, Toshiro; Tsuru, Yasuhiko; Yamamoto, Hirokazu

1995-12-31

The Alkali Metal Thermo-Electric Converter(AMTEC) is an energy conversion system that converts heat to electrical energy with high efficiency. The {beta}{double_prime}-alumina solid electrolyte (BASE) is the most important component in the AMTEC system. In this paper, the relationship among the conduction property, the microstructure and the amount of chemical component for BASE is studied. As an analysis of the chemical reaction for each component, the authors established a new BASE preparation method rather than using the conventional method. They also report the AMTFC cell performance using this electrolyte tube on which Mo or TiC electrode is filmed by the screenmore » printing method. Then, an electrochemical analysis and a heat cycle test of AMTEC cell are studied.« less

Identification of herpesvirus proteins that contribute to G1/S arrest.

PubMed

Paladino, Patrick; Marcon, Edyta; Greenblatt, Jack; Frappier, Lori

2014-04-01

Lytic infection by herpesviruses induces cell cycle arrest at the G1/S transition. This appears to be a function of multiple herpesvirus proteins, but only a minority of herpesvirus proteins have been examined for cell cycle effects. To gain a more comprehensive understanding of the viral proteins that contribute to G1/S arrest, we screened a library of over 200 proteins from herpes simplex virus type 1, human cytomegalovirus, and Epstein-Barr virus (EBV) for effects on the G1/S interface, using HeLa fluorescent, ubiquitination-based cell cycle indicator (Fucci) cells in which G1/S can be detected colorimetrically. Proteins from each virus were identified that induce accumulation of G1/S cells, predominantly tegument, early, and capsid proteins. The identification of several capsid proteins in this screen suggests that incoming viral capsids may function to modulate cellular processes. The cell cycle effects of selected EBV proteins were further verified and examined for effects on p53 and p21 as regulators of the G1/S transition. Two EBV replication proteins (BORF2 and BMRF1) were found to induce p53 but not p21, while a previously uncharacterized tegument protein (BGLF2) was found to induce p21 protein levels in a p53-independent manner. Proteomic analyses of BGLF2-interacting proteins identified interactions with the NIMA-related protein kinase (NEK9) and GEM-interacting protein (GMIP). Silencing of either NEK9 or GMIP induced p21 without affecting p53 and abrogated the ability of BGLF2 to further induce p21. Collectively, these results suggest multiple viral proteins contribute to G1/S arrest, including BGLF2, which induces p21 levels likely by interfering with the functions of NEK9 and GMIP. Most people are infected with multiple herpesviruses, whose proteins alter the infected cells in several ways. During lytic infection, the viral proteins block cell proliferation just before the cellular DNA replicates. We used a novel screening method to identify proteins from three different herpesviruses that contribute to this block. Several of the proteins we identified had previously unknown functions or were structural components of the virion. Subsets of these proteins from Epstein-Barr virus were studied for their effects on the cell cycle regulatory proteins p53 and p21, thereby identifying two proteins that induce p53 and one that induces p21 (BGLF2). We identified interactions of BGLF2 with two human proteins, both of which regulate p21, suggesting that BGLF2 induces p21 by interfering with the functions of these two host proteins. Our study indicates that multiple herpesvirus proteins contribute to the cell proliferation block, including components of the incoming virions.

Studies on hydride-forming alloys as the active material of a metal hydride electrode for a nickel metal hydride cell

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lim, H.S.; Zelter, G.R.; Allison, D.U.

1997-12-01

Multi-component AB{sub 5} hydrides are attractive replacements for the cadmium electrode in nickel-cadmium batteries. The archetype compound of the AB{sub 5} alloy class is LaNi{sub 5}, but in a typical battery electrode mischmetal is substituted for La and Ni is substituted in part by variety of metals. This paper deals with the effect on cycle life upon the partial substitution of various lanthanides for La and Sn, In, Al, Co, and Mn for Ni. The presence of Ce was shown to enhance cycle life as did Sn in some cases. An electrode of La{sub 0.67}Ce{sub 0.33}B{sub 5} alloy gave overmore » 3,500 cycles (to specific capacity of 200 mAh/g), indicating that it is a very attractive alloy for a practical Ni/MH{sub x} cell.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peek, Gregory W.; Tollefsbol, Trygve O., E-mail: trygve@uab.edu; Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, AL

Human telomerase reverse transcriptase (hTERT) is the catalytic and limiting component of telomerase and also a transcription factor. It is critical to the integrity of the ends of linear chromosomes and to the regulation, extent and rate of cell cycle progression in multicellular eukaryotes. The level of hTERT expression is essential to a wide range of bodily functions and to avoidance of disease conditions, such as cancer, that are mediated in part by aberrant level and regulation of cell cycle proliferation. Value of a gene in regulation depends on its ability to both receive input from multiple sources and transmitmore » signals to multiple effectors. The expression of hTERT and the progression of the cell cycle have been shown to be regulated by an extensive network of gene products and signaling pathways, including the PI3K/Akt and TGF-β pathways. The PI3K inhibitor PX-866 and the competitive estrogen receptor ligand raloxifene have been shown to modify progression of those pathways and, in combination, to decrease proliferation of estrogen receptor positive (ER+) MCF-7 breast cancer cells. We found that combinations of modulators of those pathways decreased not only hTERT transcription but also transcription of additional essential cell cycle regulators such as Cyclin D1. By evaluating known expression profile signatures for TGF-β pathway diversions, we confirmed additional genes such as heparin-binding epidermal growth factor-like growth factor (HB EGF) by which those pathways and their perturbations may also modify cell cycle progression. - Highlights: • PX-866 and raloxifene affect the PI3K/Akt and TGF-β pathways. • PX-866 and raloxifene down-regulate genes up-regulated in cancer. • PX-866 and raloxifene decrease transcription of hTERT and Cyclin D1. • Pathological transcription signatures can identify new defense mechanisms.« less

Development and Validation of a Slurry Model for Chemical Hydrogen Storage in Fuel Cell Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brooks, Kriston P.; Pires, Richard P.; Simmons, Kevin L.

2014-07-25

The US Department of Energy's (DOE) Hydrogen Storage Engineering Center of Excellence (HSECoE) is developing models for hydrogen storage systems for fuel cell-based light duty vehicle applications for a variety of promising materials. These transient models simulate the performance of the storage system for comparison to the DOE’s Technical Targets and a set of four drive cycles. The purpose of this research is to describe the models developed for slurry-based chemical hydrogen storage materials. The storage systems of both a representative exothermic system based on ammonia borane and endothermic system based on alane were developed and modeled in Simulink®. Oncemore » complete the reactor and radiator components of the model were validated with experimental data. The model was then run using a highway cycle, an aggressive cycle, cold-start cycle and hot drive cycle. The system design was adjusted to meet these drive cycles. A sensitivity analysis was then performed to identify the range of material properties where these DOE targets and drive cycles could be met. Materials with a heat of reaction greater than 11 kJ/mol H2 generated and a slurry hydrogen capacity of greater than 11.4% will meet the on-board efficiency and gravimetric capacity targets, respectively.« less

Alteration/deficiency in activation-3 (Ada3) plays a critical role in maintaining genomic stability

PubMed Central

Mirza, Sameer; Katafiasz, Bryan J.; Kumar, Rakesh; Wang, Jun; Mohibi, Shakur; Jain, Smrati; Gurumurthy, Channabasavaiah Basavaraju; Pandita, Tej K.; Dave, Bhavana J.; Band, Hamid; Band, Vimla

2012-01-01

Cell cycle regulation and DNA repair following damage are essential for maintaining genome integrity. DNA damage activates checkpoints in order to repair damaged DNA prior to exit to the next phase of cell cycle. Recently, we have shown the role of Ada3, a component of various histone acetyltransferase complexes, in cell cycle regulation, and loss of Ada3 results in mouse embryonic lethality. Here, we used adenovirus-Cre-mediated Ada3 deletion in Ada3fl/fl mouse embryonic fibroblasts (MEFs) to assess the role of Ada3 in DNA damage response following exposure to ionizing radiation (IR). We report that Ada3 depletion was associated with increased levels of phospho-ATM (pATM), γH2AX, phospho-53BP1 (p53BP1) and phospho-RAD51 (pRAD51) in untreated cells; however, radiation response was intact in Ada3−/− cells. Notably, Ada3−/− cells exhibited a significant delay in disappearance of DNA damage foci for several critical proteins involved in the DNA repair process. Significantly, loss of Ada3 led to enhanced chromosomal aberrations, such as chromosome breaks, fragments, deletions and translocations, which further increased upon DNA damage. Notably, the total numbers of aberrations were more clearly observed in S-phase, as compared with G₁ or G₂ phases of cell cycle with IR. Lastly, comparison of DNA damage in Ada3fl/fl and Ada3−/− cells confirmed higher residual DNA damage in Ada3−/− cells, underscoring a critical role of Ada3 in the DNA repair process. Taken together, these findings provide evidence for a novel role for Ada3 in maintenance of the DNA repair process and genomic stability. PMID:23095635

Mitotic Defects Lead to Pervasive Aneuploidy and Accompany Loss of RB1 Activity in Mouse LmnaDhe Dermal Fibroblasts

PubMed Central

Pratt, C. Herbert; Curtain, Michelle; Donahue, Leah Rae; Shopland, Lindsay S.

2011-01-01

Background Lamin A (LMNA) is a component of the nuclear lamina and is mutated in several human diseases, including Emery-Dreifuss muscular dystrophy (EDMD; OMIM ID# 181350) and the premature aging syndrome Hutchinson-Gilford progeria syndrome (HGPS; OMIM ID# 176670). Cells from progeria patients exhibit cell cycle defects in both interphase and mitosis. Mouse models with loss of LMNA function have reduced Retinoblastoma protein (RB1) activity, leading to aberrant cell cycle control in interphase, but how mitosis is affected by LMNA is not well understood. Results We examined the cell cycle and structural phenotypes of cells from mice with the Lmna allele, Disheveled hair and ears (LmnaDhe). We found that dermal fibroblasts from heterozygous LmnaDhe (LmnaDhe/+) mice exhibit many phenotypes of human laminopathy cells. These include severe perturbations to the nuclear shape and lamina, increased DNA damage, and slow growth rates due to mitotic delay. Interestingly, LmnaDhe/+ fibroblasts also had reduced levels of hypophosphorylated RB1 and the non-SMC condensin II-subunit D3 (NCAP-D3), a mitosis specific centromere condensin subunit that depends on RB1 activity. Mitotic check point control by mitotic arrest deficient-like 1 (MAD2L1) also was perturbed in LmnaDhe /+ cells. LmnaDhe /+ fibroblasts were consistently aneuploid and had higher levels of micronuclei and anaphase bridges than normal fibroblasts, consistent with chromosome segregation defects. Conclusions These data indicate that RB1 may be a key regulator of cellular phenotype in laminopathy-related cells, and suggest that the effects of LMNA on RB1 include both interphase and mitotic cell cycle control. PMID:21464947

Comparative Analysis of Transcriptomes of Macrophage Revealing the Mechanism of the Immunoregulatory Activities of a Novel Polysaccharide Isolated from Boletus speciosus Frost

PubMed Central

Ding, Xiang; Zhu, Hongqing; Hou, Yiling; Hou, Wanru; Zhang, Nan; Fu, Lei

2017-01-01

Background: The mechanism of the immunoregulatory activities of polysaccharide is still not clear. Materials and Methods: Here, we performed the B-cell, T-cell, and macrophage cell proliferation, the cell cycle analysis of macrophage cells, sequenced the transcriptomes of control group macrophages, and Boletus speciosus Frost polysaccharide (BSF-1) group macrophages using Illumina sequencing technology to identify differentially expressed genes (DEGs) to determine the molecular mechanisms of immunomodulatory activity of BSF-1 in macrophages. Results: These results suggested that BSF-1 could promote the proliferation of B-cell, T-cell, and macrophages, promote the proliferation of macrophage cells by abolishing cell cycle arrests in the G0/G1 phases, and promote cell cycle progression in S-phase and G2/M phase, which might induce cell division. A total of 12,498,414 and 11,840,624 bp paired-end reads were obtained for the control group and BSF-1 group, respectively, and they corresponded to a total size of 12.5 G bp and 11.8 G bp, respectively, after the low-quality reads and adapter sequences were removed. Approximately 81.83% of the total number of genes (8,257) were expressed reads per kilobase per million mapped reads (RPKM ≥1) and more than 1366 genes were highly expressed (RPKM >60) in the BSF-1 group. A gene ontology-enrichment analysis generated 13,042 assignments to cellular components, 13,094 assignments to biological processes, and 13,135 assignments to molecular functions. A Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis showed that the mitogen-activated protein kinase (MAPK) signaling pathways are significantly enriched for DEGs between the two cell groups. Conclusion: An analysis of transcriptome resources enabled us to examine gene expression profiles, verify differential gene expression, and select candidate signaling pathways as the mechanisms of the immunomodulatory activity of BSF-1. Based on the experimental data, we believe that the significant antitumor activities of BSF-1 in vivo mainly involve the MAPK signaling pathways. SUMMARY Boletus speciosus Frost-1 (BSF-1) could promote the proliferation of B-cell, T-cell, and macrophages, promote the proliferation of macrophage cells by abolishing cell cycle arrests in the G0/G1 phases, and promote cell cycle progression in S-phase and G2/M phase, which might induce cell divisionApproximately 81.83% of the total number of genes (8257) were expressed (reads per kilobase per million mapped reads [RPKM] =1) and more than 1366 genes were highly expressed (RPKM >60) in the BSF-1 groupA gene ontology-enrichment analysis generated 13,042 assignments to cellular components, 13,094 assignments to biological processes, and 13,135 assignments to molecular functionsA Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis showed that the mitogen-activated protein kinase signaling pathways are significantly enriched for DEGs between the two cell groups. Abbreviations used: BSF-1: Boletus speciosus Frost polysaccharide. PMID:28839373

Notch Signaling Regulates Late-Stage Epidermal Differentiation and Maintains Postnatal Hair Cycle Homeostasis

PubMed Central

Lin, Hsien-Yi; Kao, Cheng-Heng; Lin, Kurt Ming-Chao; Kaartinen, Vesa; Yang, Liang-Tung

2011-01-01

Background Notch signaling involves ligand-receptor interactions through direct cell-cell contact. Multiple Notch receptors and ligands are expressed in the epidermis and hair follicles during embryonic development and the adult stage. Although Notch signaling plays an important role in regulating differentiation of the epidermis and hair follicles, it remains unclear how Notch signaling participates in late-stage epidermal differentiation and postnatal hair cycle homeostasis. Methodology and Principal Findings We applied Cre/loxP system to generate conditional gene targeted mice that allow inactivation of critical components of Notch signaling pathway in the skin. Rbpj, the core component of all four Notch receptors, and Pofut1, an essential factor for ligand-receptor interactions, were inactivated in hair follicle lineages and suprabasal layer of the epidermis using the Tgfb3-Cre mouse line. Rbpj conditional inactivation resulted in granular parakeratosis and reactive epidermal hyperplasia. Pofut1 conditional inactivation led to ultrastructural abnormalities in the granular layer and altered filaggrin processing in the epidermis, suggesting a perturbation of the granular layer differentiation. Disruption of Pofut1 in hair follicle lineages resulted in aberrant telogen morphology, a decrease of bulge stem cell markers, and a concomitant increase of K14-positive keratinocytes in the isthmus of mutant hair follicles. Pofut1-deficent hair follicles displayed a delay in anagen re-entry and dysregulation of proliferation and apoptosis during the hair cycle transition. Moreover, increased DNA double stand breaks were detected in Pofut1-deficent hair follicles, and real time PCR analyses on bulge keratinocytes isolated by FACS revealed an induction of DNA damage response and a paucity of DNA repair machinery in mutant bulge keratinocytes. Significance our data reveal a role for Notch signaling in regulating late-stage epidermal differentiation. Notch signaling is required for postnatal hair cycle homeostasis by maintaining proper proliferation and differentiation of hair follicle stem cells. PMID:21267458

Failure analysis of a 3.5 inch, 50 ampere-hour nickel-hydrogen cell

NASA Technical Reports Server (NTRS)

Fuhr, Kenneth H.

1987-01-01

The 3.5 inch, 50 ampere-hour nickel-hydrogen cell was on a Low Earth Orbit (LEO) test regime and was being cycled at 10 C and 60 percent depth of discharge. At cycle number 511 the Automatic Control and Data Acquisition System (ACDAS) terminated the test when the end of discharge voltage dropped below the 1.00 volt cutoff. Upon removal of the stack assembly from the pressure vessel, portions of the zircar separator were found to be completely missing. Upon further examination portions of both the positive and negative plates were found to be missing from its substrate and several gas screens were damaged due to excessive heat which caused fusing. The postulated cause of failure is free electrolyte in the cell which caused oxygen channelization resulting in localized recombination which degraded the stack components.

Linking TGF-beta-mediated Cdc25A inhibition and cytoskeletal regulation through RhoA/p160(ROCK) signaling.

PubMed

Brown, Kimberly; Bhowmick, Neil A

2004-04-01

Transforming growth factor-beta (TGF-beta) can mediate G(1)/S cell-cycle inhibition and changes in the cytoskeletal organization through multiple parallel downstream signaling pathways. Recent findings regarding TGF-beta-mediated cell-cycle checkpoint control and epithelial to mesenchymal transition have converged to the RhoA/p160(ROCK) signaling pathway. The activation of TGF-beta-mediated p160(ROCK)rapidly inhibits the Cdc25A phosphatase as a component of the G(1)/S checkpoint control at the time cytoskeletal re-organization occurs. This can be likened to the ability to preserve genomic integrity in circumstances of genotoxic stress. The inactivation of the RhoA/p160(ROCK) pathway may be a mechanism by which cancer cells bypass growth inhibition even in the presence of TGF-beta.

Nuclear Migration During Retinal Development

PubMed Central

Baye, Lisa M.; Link, Brian A.

2009-01-01

In this review we focus on the mechanisms, regulation, and cellular consequences of nuclear migration in the developing retina. In the nervous system, nuclear migration is prominent during both proliferative and post-mitotic phases of development. Interkinetic nuclear migration is the process where the nucleus oscillates from the apical to basal surfaces in proliferative neuroepithelia. Proliferative nuclear movement occurs in step with the cell cycle, with M-phase being confined to the apical surface and G1-, S-, and G2-phases occurring at more basal locations. Later, following cell cycle exit, some neuron precursors migrate by nuclear translocation. In this mode of cellular migration, nuclear movement is the driving force for motility. Following discussion of the key components and important regulators for each of these processes, we present an emerging model where interkinetic nuclear migration functions to distinguish cell fates among retinal neuroepithelia. PMID:17560964

On an algorithmic definition for the components of the minimal cell.

PubMed

Martínez, Octavio; Reyes-Valdés, M Humberto

2018-01-01

Living cells are highly complex systems comprising a multitude of elements that are engaged in the many convoluted processes observed during the cell cycle. However, not all elements and processes are essential for cell survival and reproduction under steady-state environmental conditions. To distinguish between essential from expendable cell components and thus define the 'minimal cell' and the corresponding 'minimal genome', we postulate that the synthesis of all cell elements can be represented as a finite set of binary operators, and within this framework we show that cell elements that depend on their previous existence to be synthesized are those that are essential for cell survival. An algorithm to distinguish essential cell elements is presented and demonstrated within an interactome. Data and functions implementing the algorithm are given as supporting information. We expect that this algorithmic approach will lead to the determination of the complete interactome of the minimal cell, which could then be experimentally validated. The assumptions behind this hypothesis as well as its consequences for experimental and theoretical biology are discussed.

Localization of spindle checkpoint proteins in cells undergoing mitosis with unreplicated genomes.

PubMed

Johnson, Mary Kathrine; Cooksey, Amanda M; Wise, Dwayne A

2008-11-01

CHO cells can be arrested with hydoxyurea at the beginning of the DNA synthesis phase of the cell cycle. Subsequent treatment with the xanthine, caffeine, induces cells to bypass the S-phase checkpoint and enter unscheduled mitosis [Schlegel and Pardee,1986, Science 232:1264-1266]. These treated cells build a normal spindle and distribute kinetochores, unattached to chromosomes, to their daughter cells [Brinkley et al.,1988, Nature 336:251-254; Zinkowski et al.,1991, J Cell Biol 113:1091-1110; Wise and Brinkley,1997, Cell Motil Cytoskeleton 36:291-302; Balczon et al.,2003, Chromosoma 112:96-102]. To investigate how these cells distribute kinetochores to daughter cells, we analyzed the spindle checkpoint components, Mad2, CENP-E, and the 3F3 phosphoepitope, using immunofluorescence and digital microscopy. Even though the kinetochores were unpaired and DNA was fragmented, the tension, alignment, and motor components of the checkpoint were found to be present and localized as predicted in prometaphase and metaphase. This unusual mitosis proves that a cell can successfully localize checkpoint proteins and divide even when kinetochores are unpaired and fragmented. (c) 2008 Wiley-Liss, Inc.

Electrolyte volume effects on electrochemical performance and solid electrolyte interphase in Si-graphite/NMC lithium-ion pouch cells

DOE PAGES

An, Seong Jin; Li, Jianlin; Daniel, Claus; ...

2017-05-15

This study aims to explore the correlations between electrolyte volume, electrochemical performance, and properties of the solid electrolyte interphase in pouch cells with Si-graphite composite anodes. The electrolyte is 1.2 M LiPF 6 in ethylene carbonate:ethylmethyl carbonate with 10 wt.% fluoroethylene carbonate. Single layer pouch cells (100 mAh) were constructed with 15 wt.% Si-graphite/LiNi 0.5Mn 0.3CO 0.2O 2 electrodes. It is found that a minimum electrolyte volume factor of 3.1 times the total pore volume of cell components (cathode, anode, and separator) is needed for better cycling stability. Less electrolyte causes increases in ohmic and charge transfer resistances. Lithium dendritesmore » are observed when the electrolyte volume factor is low. The resistances from the anodes become significant as the cells are discharged. As a result, solid electrolyte interphase thickness grows as the electrolyte volume factor increases and is non-uniform after cycling.« less

Genetic and Quantitative Trait Locus Analysis of Cell Wall Components and Forage Digestibility in the Zheng58 × HD568 Maize RIL Population at Anthesis Stage

PubMed Central

Li, Kun; Wang, Hongwu; Hu, Xiaojiao; Ma, Feiqian; Wu, Yujin; Wang, Qi; Liu, Zhifang; Huang, Changling

2017-01-01

The plant cell wall plays vital roles in various aspects of the plant life cycle. It provides a basic structure for cells and gives mechanical rigidity to the whole plant. Some complex cell wall components are involved in signal transduction during pathogenic infection and pest infestations. Moreover, the lignification level of cell walls strongly influences the digestibility of forage plants. To determine the genetic bases of cell wall components and digestibility, quantitative trait locus (QTL) analyses for six related traits were performed using a recombinant inbred line (RIL) population from a cross between Zheng58 and HD568. Eight QTL for in vitro neutral detergent fiber (NDF) digestibility were observed, out of which only two increasing alleles came from HD568. Three QTL out of ten with alleles increasing in vitro dry matter digestibility also originated from HD568. Five–ten QTL were detected for lignin, cellulose content, acid detergent fiber, and NDF content. Among these results, 29.8% (14/47) of QTL explained >10% of the phenotypic variation in the RIL population, whereas 70.2% (33/47) explained ≤10%. These results revealed that in maize stalks, a few large-effect QTL and a number of minor-effect QTL contributed to most of the genetic components involved in cell wall biosynthesis and digestibility. PMID:28883827

Genetic and Quantitative Trait Locus Analysis of Cell Wall Components and Forage Digestibility in the Zheng58 × HD568 Maize RIL Population at Anthesis Stage.

PubMed

Li, Kun; Wang, Hongwu; Hu, Xiaojiao; Ma, Feiqian; Wu, Yujin; Wang, Qi; Liu, Zhifang; Huang, Changling

2017-01-01

The plant cell wall plays vital roles in various aspects of the plant life cycle. It provides a basic structure for cells and gives mechanical rigidity to the whole plant. Some complex cell wall components are involved in signal transduction during pathogenic infection and pest infestations. Moreover, the lignification level of cell walls strongly influences the digestibility of forage plants. To determine the genetic bases of cell wall components and digestibility, quantitative trait locus (QTL) analyses for six related traits were performed using a recombinant inbred line (RIL) population from a cross between Zheng58 and HD568. Eight QTL for in vitro neutral detergent fiber (NDF) digestibility were observed, out of which only two increasing alleles came from HD568. Three QTL out of ten with alleles increasing in vitro dry matter digestibility also originated from HD568. Five-ten QTL were detected for lignin, cellulose content, acid detergent fiber, and NDF content. Among these results, 29.8% (14/47) of QTL explained >10% of the phenotypic variation in the RIL population, whereas 70.2% (33/47) explained ≤10%. These results revealed that in maize stalks, a few large-effect QTL and a number of minor-effect QTL contributed to most of the genetic components involved in cell wall biosynthesis and digestibility.

Molecular mechanisms of cisplatin cytotoxicity in acute promyelocytic leukemia cells.

PubMed

Kumar, Sanjay; Tchounwou, Paul B

2015-12-01

Cis-diamminedichloroplatinum (II) (cisplatin) is a widely used anti-tumor drug for the treatment of a broad range of human malignancies with successful therapeutic outcomes for head and neck, ovarian, and testicular cancers. It has been found to inhibit cell cycle progression and to induce oxidative stress and apoptosis in acute promyelocytic leukemia (APL) cells. However, its molecular mechanisms of cytotoxic action are poorly understood. We hypothesized that cisplatin induces cytotoxicity through DNA adduct formation, oxidative stress, transcriptional factors (p53 and AP-1), cell cycle regulation, stress signaling and apoptosis in APL cells. We used the APL cell line as a model, and applied a variety of molecular tools to elucidate the cytotoxic mode of action of cisplatin. We found that cisplatin inhibited cell proliferation by a cytotoxicity, characterized by DNA damage and modulation of oxidative stress. Cisplatin also activated p53 and phosphorylated activator protein (AP-1) component, c-Jun at serine (63, 73) residue simultaneously leading to cell cycle arrest through stimulation of p21 and down regulation of cyclins and cyclin dependent kinases in APL cell lines. It strongly activated the intrinsic pathway of apoptosis through alteration of the mitochondrial membrane potential, release of cytochrome C, and up-regulation of caspase 3 activity. It also down regulated the p38MAPK pathway. Overall, this study highlights the molecular mechanisms that underline cisplatin toxicity to APL cells, and provides insights into selection of novel targets and/or design of therapeutic agents to treat APL.

Evidence for ovarian granulosa stem cells: telomerase activity and localization of the telomerase ribonucleic acid component in bovine ovarian follicles.

PubMed

Lavranos, T C; Mathis, J M; Latham, S E; Kalionis, B; Shay, J W; Rodgers, R J

1999-08-01

We have previously postulated that granulosa cells of developing follicles arise from a population of stem cells. Stem cells and cancer cells can divide indefinitely partly because they express telomerase. Telomerase is a ribonucleoprotein enzyme that repairs the ends of telomeres that otherwise shorten progressively upon each successive cell division. In this study we carried out cell cycle analyses and examined telomerase expression to examine our hypothesis. Preantral (60-100 microm) and small (1 mm) follicles, as well as granulosa cells from medium-sized (3 mm) and large (6-8 mm) follicles, were isolated. Cell cycle analyses and expression of Ki-67, a cell cycle-related protein, were undertaken on follicles of each size (n = 3) by flow cytometry; 12% to 16% of granulosa cells in all follicles were in the S phase, and less than 2% were in the G(2)/M phase. Telomerase activity (n = 3) was highest in the small preantral follicles, declining at the 1-mm stage and even further at the 3-mm stage. In situ hybridization histochemistry was carried out on bovine ovaries, and telomerase RNA was detected in the granulosa cells of growing follicles but not primordial follicles. Two major patterns of staining were observed in the membrana granulosa of antral follicles: staining in the middle and antral layers, and staining in the middle and basal layers. No staining was detected in oocytes. Our results strongly support our hypothesis that granulosa cells arise from a population of stem cells.

Development of advanced fuel cell system, phase 2

NASA Technical Reports Server (NTRS)

Handley, L. M.; Meyer, A. P.; Bell, W. F.

1973-01-01

A multiple task research and development program was performed to improve the weight, life, and performance characteristics of hydrogen-oxygen alkaline fuel cells for advanced power systems. Development and characterization of a very stable gold alloy catalyst was continued from Phase I of the program. A polymer material for fabrication of cell structural components was identified and its long term compatibility with the fuel cell environment was demonstrated in cell tests. Full scale partial cell stacks, with advanced design closed cycle evaporative coolers, were tested. The characteristics demonstrated in these tests verified the feasibility of developing the engineering model system concept into an advanced lightweight long life powerplant.

17-DMAG induces heat shock protein 90 functional impairment in human bladder cancer cells: knocking down the hallmark traits of malignancy.

PubMed

Karkoulis, Panagiotis K; Stravopodis, Dimitrios J; Voutsinas, Gerassimos E

2016-05-01

Heat shock protein 90 (Hsp90) is a molecular chaperone that maintains the structural and functional integrity of various protein clients involved in multiple oncogenic signaling pathways. Hsp90 holds a prominent role in tumorigenesis, as numerous members of its broad clientele are involved in the generation of the hallmark traits of cancer. 17-dimethylaminoethylamino-17-demethoxygeldanamycin (17-DMAG) specifically targets Hsp90 and interferes with its function as a molecular chaperone, impairing its intrinsic ATPase activity and undermining proper folding of multiple protein clients. In this study, we have examined the effects of 17-DMAG on the regulation of Hsp90-dependent tumorigenic signaling pathways directly implicated in cell cycle progression, survival, and motility of human urinary bladder cancer cell lines. We have used MTT-based assays, FACS analysis, Western blotting, semiquantitative PCR (sqPCR), immunofluorescence, and scratch-wound assays in RT4 (p53(wt)), RT112 (p53(wt)), T24 (p53(mt)), and TCCSUP (p53(mt)) human urinary bladder cancer cell lines. We have demonstrated that, upon exposure to 17-DMAG, bladder cancer cells display prominent cell cycle arrest and commitment to apoptotic and autophagic cell death, in a dose-dependent manner. Furthermore, 17-DMAG administration induced pronounced downregulation of multiple Hsp90 protein clients and other downstream oncogenic effectors, therefore causing inhibition of cell proliferation and decline of cell motility due to the molecular "freezing" of critical cytoskeletal components. In toto, we have clearly demonstrated the dose-dependent and cell type-specific effects of 17-DMAG on the hallmark traits of cancer, appointing Hsp90 as a key molecular component in bladder cancer targeted therapy.

The ethyl acetate extract of Phellinus linteus grown on germinated brown rice induces G0/G1 cell cycle arrest and apoptosis in human colon carcinoma HT29 cells.

PubMed

Park, Hye-Jin; Choi, Se Young; Hong, Se Mi; Hwang, Sung Gu; Park, Dong Ki

2010-07-01

It is well known that Phellinus linteus has a variety of biological functions, such as antitumor and immunomodulating activities. In our previous studies, we developed a P. linteus grown on germinated brown rice (PBR) and found that organic solvent extracts of PBR possessed immunomodulating activity to regulate a balance of cytokine network in mice. The components of PBR are ergosterol peroxide, gamma-aminobutyric acid (GABA) and Beta-glucan. In this study, we demonstrate that an organic solvent extract of P. linteus grown on PBR induced apoptotic cell death through the induction of G(0)/G(1) arrest of cell cycle and the apoptosis via DNA fragmentation in human colon carcinoma HT-29 cells. Cell death induced by the extract of P. linteus grown on PBR was shown to be associated with the upregulation of p21(CIP1/WAF1), the downregulation of cyclin D1, anti-apoptotic protein, Bcl-2, the release of cytochrome c, and the activation of caspase-9, caspase-3 and caspase-8. This study suggests that the ethyl acetate extract of P. linteus grown on PBR induces apoptosis accompanied by cell cycle arrest at G(0)/G(1) phase and regulates apoptosis-regulatory proteins, which may be applicable to anticancer therapy.

Delayed luminescence to monitor programmed cell death induced by berberine on thyroid cancer cells

NASA Astrophysics Data System (ADS)

Scordino, Agata; Campisi, Agata; Grasso, Rosaria; Bonfanti, Roberta; Gulino, Marisa; Iauk, Liliana; Parenti, Rosalba; Musumeci, Francesco

2014-11-01

Correlation between apoptosis and UVA-induced ultraweak photon emission delayed luminescence (DL) from tumor thyroid cell lines was investigated. In particular, the effects of berberine, an alkaloid that has been reported to have anticancer activities, on two cancer cell lines were studied. The FTC-133 and 8305C cell lines, as representative of follicular and anaplastic thyroid human cancer, respectively, were chosen. The results show that berberine is able to arrest cell cycle and activate apoptotic pathway as shown in both cell lines by deoxyribonucleic acid fragmentation, caspase-3 cleavage, p53 and p27 protein overexpression. In parallel, changes in DL spectral components after berberine treatment support the hypothesis that DL from human cells originates mainly from mitochondria, since berberine acts especially at the mitochondrial level. The decrease of DL blue component for both cell lines could be related to the decrease of intra-mitochondrial nicotinamide adenine dinucleotide and may be a hallmark of induced apoptosis. In contrast, the response in the red spectral range is different for the two cell lines and may be ascribed to a different iron homeostasis.

Evodiamine selectively targets cancer stem-like cells through the p53-p21-Rb pathway

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, Seula; Woo, Jong Kyu; Jung, Yuchae

In spite of the recent improvements, the resistance to chemotherapy/radiotherapy followed by relapse is the main hurdle for the successful treatment of breast cancer, a leading cause of death in women. A small population of breast cancer cells that have stem-like characteristics (cancer stem-like cells; CSLC) may contribute to this resistance and relapse. Here, we report on a component of a traditional Chinese medicine, evodiamine, which selectively targets CSLC of breast cancer cell lines MCF7 and MDAMB 231 at a concentration that does show a little or no cytotoxic effect on bulk cancer cells. While evodiamine caused the accumulation of bulkmore » cancer cells at the G2/M phase, it did not hold CSLC in a specific cell cycle phase but instead, selectively killed CSLC. This was not due to the culture of CSLC in suspension or without FBS. A proteomic analysis and western blotting revealed that evodiamine changed the expression of cell cycle regulating molecules more efficiently in CSLC cells than in bulk cancer cells. Surprisingly, evodiamine selectively activated p53 and p21 and decreased inactive Rb, the master molecules in G1/S checkpoint. These data collectively suggest a novel mechanism involving CSLC-specific targeting by evodiamine and its possible use to the therapy of breast cancer. - Highlights: • Evodiamine selectively kills breast cancer stem like cells at G1 phase. • Evodiamine utilizes different mechanism of cell cycle modulation in CSLC and in bulk cancer cells. • Evodiamine activate the p53, p21 and Rb pathway.« less

5,6,7,3′,4′,5′-Hexamethoxyflavone inhibits growth of triple-negative breast cancer cells via suppression of MAPK and Akt signaling pathways and arresting cell cycle

PubMed Central

Torres, Haydee; McDonnell, Susan; Van Slambrouck, Severine

2017-01-01

Natural components continue to be an important source for the discovery and development of novel anticancer agents. Polymethoxyflavones are a class of flavonoids found in citrus fruits and medicinal plants used in traditional medicine. In the present study, the anticancer activity of the well-known nobiletin (5,6,7,8,3′,4′-hexamethoxyflavone) was compared against its less studied structural isomer 5,6,7,3′,4′,5′-hexamethoxyflavone. These compounds were evaluated on the Hs578T triple-negative breast cancer cell line and its more migratory subclone Hs578Ts(i)8. 5,6,7,3′,4′,5′-hexamethoxyflavone was found to be less toxic than nobiletin, while a similar growth inhibitory effect was observed after 72 h. Additionally, 5,6,7,3′,4′,5′-hexamethoxyflavone arrested the cell cycle in the G2/M phase, while no effect was observed on apoptosis or the migratory behavior of these cells. Furthermore, mechanistic studies revealed that the growth inhibition was concomitant with reduced phosphorylation levels of signaling molecules in the MAPK and Akt pathways as well as cell cycle regulators, involved in regulating cell proliferation, survival and cell cycle. In summary, the present study is the first to report on the anticancer activities of 5,6,7,3′,4′,5′-hexamethoxyflavone and to provide evidence that this flavone could have a greater potential than nobiletin for prevention or treatment of triple-negative breast cancer. PMID:29039514

Final Technical Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Michael Laub

2008-12-29

Our team of investigators from MIT (Michael Laub) and Stanford (Harley McAdams and Lucy Shapiro) conducted a multi-faceted, systematic experimental analysis of the 106 Caulobacter two-component signal transduction system proteins (62 histidine kinases and 44 response regulators) to understand how they coordinate cell cycle progression, metabolism, and response to environmental changes. These two-component signaling proteins were characterized at the genetic, biochemical, and genomic levels. The results generated by our laboratories have provided numerous insights into how Caulobacter cells sense and respond to a myriad of signals. As nearly all bacteria use two-component signaling for cell regulation, the results from thismore » project help to deepen our general understanding of bacterial signal transduction. The tools and approaches developed can be applied to other bacteria. In particular, work from the Laub laboratory now enables the systematic, rational rewiring of two-component signaling proteins, a major advance that stands to impact synthetic biology and the development of biosensors and other designer molecular circuits. Results are summarized from our work. Each section lists publications and publicly-available resources which result from the work described.« less

Effect of component compression on the initial performance of an IPV nickel-hydrogen cell

NASA Technical Reports Server (NTRS)

Gahn, Randall F.

1987-01-01

An experimental method was developed for evaluating the effect of component compression on the charge and discharge voltage characteristics of a 3 1/2 in. diameter boiler plate cell. A standard boiler plate pressure vessel was modified by the addition of a mechanical feedthrough on the bottom of the vessel which permitted different compressions to be applied to the components without disturbing the integrity of the stack. Compression loadings from 0.94 to 27.4 psi were applied by suspending weights from the feedthrough rod. Cell voltages were measured for 0.96-C, 55-min charge and for 1.37-C, 35-min and 2-C, 24-min discharges. An initial change in voltage performance on both charge and discharge as the loading increased was attributed to seating of the components. Subsequent variation of the compression from 2.97 to 27.4 psi caused only minor changes in either the charge or the discharge voltages. Several one month open-circuit voltage stands and 1100 cycles under LEO conditions at the maximum loading have produced no change in performance.

Effect of component compression on the initial performance of an IPV nickel-hydrogen cell. [Individual Pressure Vessel

NASA Technical Reports Server (NTRS)

Gahn, Randall F.

1987-01-01

An experimental method was developed for evaluating the effect of component compression on the charge and discharge voltage characteristics of a 3 1/2 in. diameter boiler plate cell. A standard boiler plate pressure vessel was modified by the addition of a mechanical feedthrough on the bottom of the vessel which permitted different compressions to be applied to the components without disturbing the integrity of the stack. Compression loadings from 0.94 to 27.4 psi were applied by suspending weights from the feedthrough rod. Cell voltages were measured for 0.96-C, 55-min charge and for 1.37-C, 35-min and 2-C, 24-min discharges. An initial change in voltage performance on both charge and discharge as the loading increased was attributed to seating of the components. Subsequent variation of the compression from 2.97 to 27.4 psi caused only minor changes in either the charge or the discharge voltages. Several one month open-circuit voltage stands and 1100 cycles under LEO conditions at the maximum loading have produced no change in performance.

Functions and substrates of NEDDylation during cell cycle in the silkworm, Bombyx mori.

PubMed

Li, Zhiqing; Cui, Qixin; Wang, Xiaoyan; Li, Bingqian; Zhao, Dongchao; Xia, Qingyou; Zhao, Ping

2017-11-01

NEDDylation, a post-translational modification mediated by the conjugation of the ubiquitin-like protein Nedd8 to specific substrates, is an essential biological process that regulates cell cycle progression in eukaryotes. Here, we report the conservation of NEDDylation machinery and NEDDylated proteins in the silkworm, Bombyx mori. We have identified all the components necessary for reversible NEDDylation in the silkworm including Nedd8, E1, E2, E3, and deNEDDylation enzymes. By the approach of RNAi-mediated gene silencing, it was shown that knockdown of BmNedd8 and the conjugating enzymes decreased the global level of NEDDylation, while knockdown of deNEDDylation enzymes increased the prevalence of this modification in cultured silkworm cells. Moreover, the lack of the NEDDylation system caused cell cycle arrest at the G2/M phase and resulted in defects in chromosome congression and segregation. Using the wild-type and mutants of BmNedd8, we identified the specific substrates of BmNedd8, which are involved in the regulation for many cellular processes, including ribosome biogenesis, spliceosome structure, spindle formation, metabolism, and RNA biogenesis. This clearly demonstrates that the NEDDylation system is able to control multiple pathways in the silkworm. Altogether, the information on the functions and substrates of the NEDDylation system presented here could provide a basis for future investigations of protein NEDDylation and its regulatory mechanism on cell cycle progression in the silkworm. Copyright © 2017. Published by Elsevier Ltd.

Cell cycle-dependent transcription factors control the expression of yeast telomerase RNA.

PubMed

Dionne, Isabelle; Larose, Stéphanie; Dandjinou, Alain T; Abou Elela, Sherif; Wellinger, Raymund J

2013-07-01

Telomerase is a specialized ribonucleoprotein that adds repeated DNA sequences to the ends of eukaryotic chromosomes to preserve genome integrity. Some secondary structure features of the telomerase RNA are very well conserved, and it serves as a central scaffold for the binding of associated proteins. The Saccharomyces cerevisiae telomerase RNA, TLC1, is found in very low copy number in the cell and is the limiting component of the known telomerase holoenzyme constituents. The reasons for this low abundance are unclear, but given that the RNA is very stable, transcriptional control mechanisms must be extremely important. Here we define the sequences forming the TLC1 promoter and identify the elements required for its low expression level, including enhancer and repressor elements. Within an enhancer element, we found consensus sites for Mbp1/Swi4 association, and chromatin immunoprecipitation (ChIP) assays confirmed the binding of Mbp1 and Swi4 to these sites of the TLC1 promoter. Furthermore, the enhancer element conferred cell cycle-dependent regulation to a reporter gene, and mutations in the Mbp1/Swi4 binding sites affected the levels of telomerase RNA and telomere length. Finally, ChIP experiments using a TLC1 RNA-binding protein as target showed cell cycle-dependent transcription of the TLC1 gene. These results indicate that the budding yeast TLC1 RNA is transcribed in a cell cycle-dependent fashion late in G1 and may be part of the S phase-regulated group of genes involved in DNA replication.

Anaphase-promoting complex/cyclosome protein Cdc27 is a target for curcumin-induced cell cycle arrest and apoptosis.

PubMed

Lee, Seung Joon; Langhans, Sigrid A

2012-01-26

Curcumin (diferuloylmethane), the yellow pigment in the Asian spice turmeric, is a hydrophobic polyphenol from the rhizome of Curcuma longa. Because of its chemopreventive and chemotherapeutic potential with no discernable side effects, it has become one of the major natural agents being developed for cancer therapy. Accumulating evidence suggests that curcumin induces cell death through activation of apoptotic pathways and inhibition of cell growth and proliferation. The mitotic checkpoint, or spindle assembly checkpoint (SAC), is the major cell cycle control mechanism to delay the onset of anaphase during mitosis. One of the key regulators of the SAC is the anaphase promoting complex/cyclosome (APC/C) which ubiquitinates cyclin B and securin and targets them for proteolysis. Because APC/C not only ensures cell cycle arrest upon spindle disruption but also promotes cell death in response to prolonged mitotic arrest, it has become an attractive drug target in cancer therapy. Cell cycle profiles were determined in control and curcumin-treated medulloblastoma and various other cancer cell lines. Pull-down assays were used to confirm curcumin binding. APC/C activity was determined using an in vitro APC activity assay. We identified Cdc27/APC3, a component of the APC/C, as a novel molecular target of curcumin and showed that curcumin binds to and crosslinks Cdc27 to affect APC/C function. We further provide evidence that curcumin preferably induces apoptosis in cells expressing phosphorylated Cdc27 usually found in highly proliferating cells. We report that curcumin directly targets the SAC to induce apoptosis preferably in cells with high levels of phosphorylated Cdc27. Our studies provide a possible molecular mechanism why curcumin induces apoptosis preferentially in cancer cells and suggest that phosphorylation of Cdc27 could be used as a biomarker to predict the therapeutic response of cancer cells to curcumin.

Anaphase-promoting complex/cyclosome protein Cdc27 is a target for curcumin-induced cell cycle arrest and apoptosis

PubMed Central

2012-01-01

Background Curcumin (diferuloylmethane), the yellow pigment in the Asian spice turmeric, is a hydrophobic polyphenol from the rhizome of Curcuma longa. Because of its chemopreventive and chemotherapeutic potential with no discernable side effects, it has become one of the major natural agents being developed for cancer therapy. Accumulating evidence suggests that curcumin induces cell death through activation of apoptotic pathways and inhibition of cell growth and proliferation. The mitotic checkpoint, or spindle assembly checkpoint (SAC), is the major cell cycle control mechanism to delay the onset of anaphase during mitosis. One of the key regulators of the SAC is the anaphase promoting complex/cyclosome (APC/C) which ubiquitinates cyclin B and securin and targets them for proteolysis. Because APC/C not only ensures cell cycle arrest upon spindle disruption but also promotes cell death in response to prolonged mitotic arrest, it has become an attractive drug target in cancer therapy. Methods Cell cycle profiles were determined in control and curcumin-treated medulloblastoma and various other cancer cell lines. Pull-down assays were used to confirm curcumin binding. APC/C activity was determined using an in vitro APC activity assay. Results We identified Cdc27/APC3, a component of the APC/C, as a novel molecular target of curcumin and showed that curcumin binds to and crosslinks Cdc27 to affect APC/C function. We further provide evidence that curcumin preferably induces apoptosis in cells expressing phosphorylated Cdc27 usually found in highly proliferating cells. Conclusions We report that curcumin directly targets the SAC to induce apoptosis preferably in cells with high levels of phosphorylated Cdc27. Our studies provide a possible molecular mechanism why curcumin induces apoptosis preferentially in cancer cells and suggest that phosphorylation of Cdc27 could be used as a biomarker to predict the therapeutic response of cancer cells to curcumin. PMID:22280307

TRAIP promotes DNA damage response during genome replication and is mutated in primordial dwarfism.

PubMed

Harley, Margaret E; Murina, Olga; Leitch, Andrea; Higgs, Martin R; Bicknell, Louise S; Yigit, Gökhan; Blackford, Andrew N; Zlatanou, Anastasia; Mackenzie, Karen J; Reddy, Kaalak; Halachev, Mihail; McGlasson, Sarah; Reijns, Martin A M; Fluteau, Adeline; Martin, Carol-Anne; Sabbioneda, Simone; Elcioglu, Nursel H; Altmüller, Janine; Thiele, Holger; Greenhalgh, Lynn; Chessa, Luciana; Maghnie, Mohamad; Salim, Mahmoud; Bober, Michael B; Nürnberg, Peter; Jackson, Stephen P; Hurles, Matthew E; Wollnik, Bernd; Stewart, Grant S; Jackson, Andrew P

2016-01-01

DNA lesions encountered by replicative polymerases threaten genome stability and cell cycle progression. Here we report the identification of mutations in TRAIP, encoding an E3 RING ubiquitin ligase, in patients with microcephalic primordial dwarfism. We establish that TRAIP relocalizes to sites of DNA damage, where it is required for optimal phosphorylation of H2AX and RPA2 during S-phase in response to ultraviolet (UV) irradiation, as well as fork progression through UV-induced DNA lesions. TRAIP is necessary for efficient cell cycle progression and mutations in TRAIP therefore limit cellular proliferation, providing a potential mechanism for microcephaly and dwarfism phenotypes. Human genetics thus identifies TRAIP as a component of the DNA damage response to replication-blocking DNA lesions.

CDK1 Prevents Unscheduled PLK4-STIL Complex Assembly in Centriole Biogenesis.

PubMed

Zitouni, Sihem; Francia, Maria E; Leal, Filipe; Montenegro Gouveia, Susana; Nabais, Catarina; Duarte, Paulo; Gilberto, Samuel; Brito, Daniela; Moyer, Tyler; Kandels-Lewis, Steffi; Ohta, Midori; Kitagawa, Daiju; Holland, Andrew J; Karsenti, Eric; Lorca, Thierry; Lince-Faria, Mariana; Bettencourt-Dias, Mónica

2016-05-09

Centrioles are essential for the assembly of both centrosomes and cilia. Centriole biogenesis occurs once and only once per cell cycle and is temporally coordinated with cell-cycle progression, ensuring the formation of the right number of centrioles at the right time. The formation of new daughter centrioles is guided by a pre-existing, mother centriole. The proximity between mother and daughter centrioles was proposed to restrict new centriole formation until they separate beyond a critical distance. Paradoxically, mother and daughter centrioles overcome this distance in early mitosis, at a time when triggers for centriole biogenesis Polo-like kinase 4 (PLK4) and its substrate STIL are abundant. Here we show that in mitosis, the mitotic kinase CDK1-CyclinB binds STIL and prevents formation of the PLK4-STIL complex and STIL phosphorylation by PLK4, thus inhibiting untimely onset of centriole biogenesis. After CDK1-CyclinB inactivation upon mitotic exit, PLK4 can bind and phosphorylate STIL in G1, allowing pro-centriole assembly in the subsequent S phase. Our work shows that complementary mechanisms, such as mother-daughter centriole proximity and CDK1-CyclinB interaction with centriolar components, ensure that centriole biogenesis occurs once and only once per cell cycle, raising parallels to the cell-cycle regulation of DNA replication and centromere formation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Advanced nickel-hydrogen spacecraft battery development

NASA Technical Reports Server (NTRS)

Coates, Dwaine K.; Fox, Chris L.; Standlee, D. J.; Grindstaff, B. K.

1994-01-01

Eagle-Picher currently has several advanced nickel-hydrogen (NiH2) cell component and battery designs under development including common pressure vessel (CPV), single pressure vessel (SPV), and dependent pressure vessel (DPV) designs. A CPV NiH2 battery, utilizing low-cost 64 mm (2.5 in.) cell diameter technology, has been designed and built for multiple smallsat programs, including the TUBSAT B spacecraft which is currently scheduled (24 Nov. 93) for launch aboard a Russian Proton rocket. An advanced 90 mm (3.5 in.) NiH2 cell design is currently being manufactured for the Space Station Freedom program. Prototype 254 mm (10 in.) diameter SPV batteries are currently under construction and initial boilerplate testing has shown excellent results. NiH2 cycle life testing is being continued at Eagle-Picher and IPV cells have currently completed more than 89,000 accelerated LEO cycles at 15% DOD, 49,000 real-time LEO cycles at 30 percent DOD, 37,800 cycles under a real-time LEO profile, 30 eclipse seasons in accelerated GEO, and 6 eclipse seasons in real-time GEO testing at 75 percent DOD maximum. Nickel-metal hydride battery development is continuing for both aerospace and electric vehicle applications. Eagle-Picher has also developed an extensive range of battery evaluation, test, and analysis (BETA) measurement and control equipment and software, based on Hewlett-Packard computerized data acquisition/control hardware.

Characterization of cyclin-dependent kinases and Cdc2/Cdc28 kinase subunits in Trichomonas vaginalis.

PubMed

Amador, Erick; López-Pacheco, Karla; Morales, Nataly; Coria, Roberto; López-Villaseñor, Imelda

2017-04-01

Cyclin-dependent kinases (CDKs) have important roles in regulating key checkpoints between stages of the cell cycle. Their activity is tightly regulated through a variety of mechanisms, including through binding with cyclin proteins and the Cdc2/Cdc28 kinase subunit (CKS), and their phosphorylation at specific amino acids. Studies of the components involved in cell cycle control in parasitic protozoa are limited. Trichomonas vaginalis is the causative agent of trichomoniasis in humans and is therefore important in public health; however, some of the basic biological processes used by this organism have not been defined. Here, we characterized proteins potentially involved in cell cycle regulation in T. vaginalis. Three genes encoding protein kinases were identified in the T. vaginalis genome, and the corresponding recombinant proteins (TvCRK1, TvCRK2, TvCRK5) were studied. These proteins displayed similar sequence features to CDKs. Two genes encoding CKSs were also identified, and the corresponding recombinant proteins were found to interact with TvCRK1 and TvCRK2 by a yeast two-hybrid system. One putative cyclin B protein from T. vaginalis was found to bind to and activate the kinase activities of TvCRK1 and TvCRK5, but not TvCRK2. This work is the first characterization of proteins involved in cell cycle control in T. vaginalis.

Modeling Yeast Cell Polarization Induced by Pheromone Gradients

NASA Astrophysics Data System (ADS)

Yi, Tau-Mu; Chen, Shanqin; Chou, Ching-Shan; Nie, Qing

2007-07-01

Yeast cells respond to spatial gradients of mating pheromones by polarizing and projecting up the gradient toward the source. It is thought that they employ a spatial sensing mechanism in which the cell compares the concentration of pheromone at different points on the cell surface and determines the maximum point, where the projection forms. Here we constructed the first spatial mathematical model of the yeast pheromone response that describes the dynamics of the heterotrimeric and Cdc42p G-protein cycles, which are linked in a cascade. Two key performance objectives of this system are (1) amplification—converting a shallow external gradient of ligand to a steep internal gradient of protein components and (2) tracking—following changes in gradient direction. We used simulations to investigate amplification mechanisms that allow tracking. We identified specific strategies for regulating the spatial dynamics of the protein components (i.e. their changing location in the cell) that would enable the cell to achieve both objectives.

A novel Hsp70 inhibitor prevents cell intoxication with the actin ADP-ribosylating Clostridium perfringens iota toxin

PubMed Central

Ernst, Katharina; Liebscher, Markus; Mathea, Sebastian; Granzhan, Anton; Schmid, Johannes; Popoff, Michel R.; Ihmels, Heiko; Barth, Holger; Schiene-Fischer, Cordelia

2016-01-01

Hsp70 family proteins are folding helper proteins involved in a wide variety of cellular pathways. Members of this family interact with key factors in signal transduction, transcription, cell-cycle control, and stress response. Here, we developed the first Hsp70 low molecular weight inhibitor specifically targeting the peptide binding site of human Hsp70. After demonstrating that the inhibitor modulates the Hsp70 function in the cell, we used the inhibitor to show for the first time that the stress-inducible chaperone Hsp70 functions as molecular component for entry of a bacterial protein toxin into mammalian cells. Pharmacological inhibition of Hsp70 protected cells from intoxication with the binary actin ADP-ribosylating iota toxin from Clostridium perfringens, the prototype of a family of enterotoxins from pathogenic Clostridia and inhibited translocation of its enzyme component across cell membranes into the cytosol. This finding offers a starting point for novel therapeutic strategies against certain bacterial toxins. PMID:26839186

Test Results of a Ten Cell Bipolar Nickel-hydrogen Battery

NASA Technical Reports Server (NTRS)

Cataldo, R. L.

1984-01-01

A study was initiated to design and evaluate a new design concept for nickel-hydrogen cells. This concept involved constructing a battery in a bipolar stack with cells consisting of a one plate for each nickel and hydrogen electrode. Preliminary designs at the system level of this concept promised improvements in both volumetric and gravimetric energy densities, thermal management, life extension, costs, and peak power capability over more conventional designs. Test results were most encouraging. This preprototype battery, built with less than ideal components and hardware, exceeded expectations. A total of 2000 LEO cycles at 80 percent depth of discharge were accrued. A cycle life goal of 30,000 cycles appears achievable with minor design changes. These improvements include advanced technology nickel electrodes, insulated bipolar plates and specifically designed frames to minimize shunt currents. The discharge rate capability of this design exceeds 25C. At the 10C discharge rate, 80% of the battery capacity can be withdrawn in six minutes. This data shows that the bipolar design is well suited for those applications requiring high peak power pulses.

Investigating mitochondrial dysfunction in human lung cells exposed to redox-active PM components.

PubMed

Lavrich, Katelyn S; Corteselli, Elizabeth M; Wages, Phillip A; Bromberg, Philip A; Simmons, Steven O; Gibbs-Flournoy, Eugene A; Samet, James M

2018-03-01

Exposure to ambient particulate matter (PM) causes cardiopulmonary morbidity and mortality through mechanisms that involve oxidative stress. 1,2-naphthoquinone (1,2-NQ) is a ubiquitous component of PM and a potent redox-active electrophile. We previously reported that 1,2-NQ increases mitochondrial H 2 O 2 production through an unidentified mechanism. We sought to characterize the effects of 1,2-NQ exposure on mitochondrial respiration as a source of H 2 O 2 in human airway epithelial cells. We measured the effects of acute exposure to 1,2-NQ on oxygen consumption rate (OCR) in the human bronchial epithelial cell line BEAS-2B and mitochondrial preparations using extracellular flux analysis. Complex-specific assays and NADPH depletion by glucose deprivation distinguished between mitochondrial and non-mitochondrial oxygen utilization. 1,2-NQ exposure of BEAS cells caused a rapid, marked dose-dependent increase in OCR that was independent of mitochondrial respiration, exceeded the OCR observed after mitochondrial uncoupling, and remained sensitive to NADPH depletion, implicating extra-mitochondrial redox cycling processes. Similar effects were observed with the environmentally relevant redox-cycling quinones 1,4-naphthoquinone and 9,10-phenanthrenequinone, but not with quinones that do not redox cycle, such as 1,4-benzoquinone. In mitochondrial preparations, 1,2-NQ caused a decrease in Complex I-linked substrate oxidation, suggesting impairment of pyruvate utilization or transport, a novel mechanism of mitochondrial inhibition by an environmental exposure. This study also highlights the methodological utility and challenges in the use of extracellular flux analysis to elucidate the mechanisms of action of redox-active electrophiles present in ambient air. Published by Elsevier Inc.

Missing Value Monitoring Enhances the Robustness in Proteomics Quantitation.

PubMed

Matafora, Vittoria; Corno, Andrea; Ciliberto, Andrea; Bachi, Angela

2017-04-07

In global proteomic analysis, it is estimated that proteins span from millions to less than 100 copies per cell. The challenge of protein quantitation by classic shotgun proteomic techniques relies on the presence of missing values in peptides belonging to low-abundance proteins that lowers intraruns reproducibility affecting postdata statistical analysis. Here, we present a new analytical workflow MvM (missing value monitoring) able to recover quantitation of missing values generated by shotgun analysis. In particular, we used confident data-dependent acquisition (DDA) quantitation only for proteins measured in all the runs, while we filled the missing values with data-independent acquisition analysis using the library previously generated in DDA. We analyzed cell cycle regulated proteins, as they are low abundance proteins with highly dynamic expression levels. Indeed, we found that cell cycle related proteins are the major components of the missing values-rich proteome. Using the MvM workflow, we doubled the number of robustly quantified cell cycle related proteins, and we reduced the number of missing values achieving robust quantitation for proteins over ∼50 molecules per cell. MvM allows lower quantification variance among replicates for low abundance proteins with respect to DDA analysis, which demonstrates the potential of this novel workflow to measure low abundance, dynamically regulated proteins.

Nucleoporins redistribute inside the nucleus after cell cycle arrest induced by histone deacetylases inhibition.

PubMed

Pérez-Garrastachu, Miguel; Arluzea, Jon; Andrade, Ricardo; Díez-Torre, Alejandro; Urtizberea, Marta; Silió, Margarita; Aréchaga, Juan

2017-09-03

Nucleoporins are the main components of the nuclear-pore complex (NPC) and were initially considered as mere structural elements embedded in the nuclear envelope, being responsible for nucleocytoplasmic transport. Nevertheless, several recent scientific reports have revealed that some nucleoporins participate in nuclear processes such as transcription, replication, DNA repair and chromosome segregation. Thus, the interaction of NPCs with chromatin could modulate the distribution of chromosome territories relying on the epigenetic state of DNA. In particular, the nuclear basket proteins Tpr and Nup153, and the FG-nucleoporin Nup98 seem to play key roles in all these novel functions. In this work, histone deacetylase inhibitors (HDACi) were used to induce a hyperacetylated state of chromatin and the behavior of the mentioned nucleoporins was studied. Our results show that, after HDACi treatment, Tpr, Nup153 and Nup98 are translocated from the nuclear pore toward the interior of the cell nucleus, accumulating as intranuclear nucleoporin clusters. These transitory structures are highly dynamic, and are mainly present in the population of cells arrested at the G0/G1 phase of the cell cycle. Our results indicate that the redistribution of these nucleoporins from the nuclear envelope to the nuclear interior may be implicated in the early events of cell cycle initialization, particularly during the G1 phase transition.

Electrochemical devices utilizing molten alkali metal electrode-reactant

DOEpatents

Hitchcock, David C.; Mailhe, Catherine C.; De Jonghe, Lutgard C.

1986-01-01

Electrochemical cells are provided with a reactive metal to reduce the oxide of the alkali metal electrode-reactant. Cells employing a molten alkali metal electrode, e.g., sodium, in contact with a ceramic electrolyte, which is a conductor of the ions of the alkali metal forming the electrode, exhibit a lower resistance when a reactive metal, e.g., vanadium, is allowed to react with and reduce the alkali metal oxide. Such cells exhibit less degradation of the electrolyte and of the glass seals often used to joining the electrolyte to the other components of the cell under cycling conditions.

Electrochemical devices utilizing molten alkali metal electrode-reactant

DOEpatents

Hitchcock, D.C.; Mailhe, C.C.; De Jonghe, L.C.

1985-07-10

Electrochemical cells are provided with a reactive metal to reduce the oxide of the alkali metal electrode-reactant. Cells employing a molten alkali metal electrode, e.g., sodium, in contact with a ceramic electrolyte, which is a conductor of the ions of the alkali metal forming the electrode, exhibit a lower resistance when a reactive metal, e.g., vanadium, is allowed to react with and reduce the alkali metal oxide. Such cells exhibit less degradation of the electrolyte and of the glass seals often used to joining the electrolyte to the other components of the cell under cycling conditions.

A transient plasticity study and low cycle fatigue analysis of the Space Station Freedom photovoltaic solar array blanket

NASA Technical Reports Server (NTRS)

Armand, Sasan C.; Liao, Mei-Hwa; Morris, Ronald W.

1990-01-01

The Space Station Freedom photovoltaic solar array blanket assembly is comprised of several layers of materials having dissimilar elastic, thermal, and mechanical properties. The operating temperature of the solar array, which ranges from -75 to +60 C, along with the material incompatibility of the blanket assembly components combine to cause an elastic-plastic stress in the weld points of the assembly. The weld points are secondary structures in nature, merely serving as electrical junctions for gathering the current. The thermal mechanical loading of the blanket assembly operating in low earth orbit continually changes throughout each 90 min orbit, which raises the possibility of fatigue induced failure. A series of structural analyses were performed in an attempt to predict the fatigue life of the solar cell in the Space Station Freedom photovoltaic array blanket. A nonlinear elastic-plastic MSC/NASTRAN analysis followed by a fatigue calculation indicated a fatigue life of 92,000 to 160,000 cycles for the solar cell weld tabs. Additional analyses predict a permanent buckling phenomenon in the copper interconnect after the first loading cycle. This should reduce or eliminate the pulling of the copper interconnect on the joint where it is welded to the silicon solar cell. It is concluded that the actual fatigue life of the solar array blanket assembly should be significantly higher than the calculated 92,000 cycles, and thus the program requirement of 87,500 cycles (orbits) will be met. Another important conclusion that can be drawn from the overall analysis is that, the strain results obtained from the MSC/NASTRAN nonlinear module are accurate to use for low-cycle fatigue analysis, since both thermal cycle testing of solar cells and analysis have shown higher fatigue life than the minimum program requirement of 87,500 cycles.

LIN-23, an E3 Ubiquitin Ligase Component, Is Required for the Repression of CDC-25.2 Activity during Intestinal Development in Caenorhabditis elegans.

PubMed

Son, Miseol; Kawasaki, Ichiro; Oh, Bong-Kyeong; Shim, Yhong-Hee

2016-11-30

Caenorhabditis elegans ( C. elegans ) utilizes two different cell-cycle modes, binucleations during the L1 larval stage and endoreduplications at four larval moltings, for its postembryonic intestinal development. Previous genetic studies indicated that CDC-25.2 is specifically required for binucleations at the L1 larval stage and is repressed before endoreduplications. Furthermore, LIN-23, the C. elegans β-TrCP ortholog, appears to function as a repressor of CDC-25.2 to prevent excess intestinal divisions. We previously reported that intestinal hyperplasia in lin-23(e1883) mutants was effectively suppressed by the RNAi depletion of cdc-25.2 . Nevertheless, LIN-23 targeting CDC-25.2 for ubiquitination as a component of E3 ubiquitin ligase has not yet been tested. In this study, LIN-23 is shown to be the major E3 ubiquitin ligase component, recognizing CDC-25.2 to repress their activities for proper transition of cell-cycle modes during the C. elegans postembryonic intestinal development. In addition, for the first time that LIN-23 physically interacts with both CDC-25.1 and CDC-25.2 and facilitates ubiquitination for timely regulation of their activities during the intestinal development.

3D additive manufactured 316L components microstructural features and changes induced by working life cycles

NASA Astrophysics Data System (ADS)

Pace, M. L.; Guarnaccio, A.; Dolce, P.; Mollica, D.; Parisi, G. P.; Lettino, A.; Medici, L.; Summa, V.; Ciancio, R.; Santagata, A.

2017-10-01

The ability of processing through laser beams different kinds of metallic powders for direct production of 3D components with complex geometries has been gaining an impressive and growing attention for specific industrial applications. The process which can be distinguished as Selective Laser Sintering or Selective Laser Melting is even considered, more generally, as Additive Manufacturing where layer by layer material is built by the interaction between a laser beam and a powder bed. The rapid heating of the powder due to the laser beam energy transfer process followed by a rapid cooling rate induces within the manufactured material a cellular structure with fine sub-grains, which are in the range of few hundreds of micrometers. These metastable structures, which are smaller than the grain size in conventionally manufactured 316L stainless steel components, can undertake towards a recrystallization process due to either heat or mechanical treatments. For instance, when sub-grain boundaries of the cells are enriched with Mo and higher concentration of dislocation, dynamical processes occur generating local residual stresses. In these circumstances the segregation of Mo in cell boundaries is out of thermodynamic equilibrium conditions so that microstructures and phases are metastable. In the range of 1100-1400 °C heat treatments a complete dissolution of Mo in the Fe matrix with a gradual disappearance of sub-microns cell is observed feeding the growth of larger austenitic sub-grains formation. It follows a higher degree of Mo dissolution in the material matrix and a decrease of dislocation's concentration (Saeidi et al., 2015) [1]. In the work here presented we point out which are the microstructural features of stainless steel 316L components realized by Additive Manufacturing. Furthermore, the occurrence of a microstructural evolution is presented after experiencing to fatigue of 80000 cycles some door joints obtained by this technique. A decrease of dislocation's number, an increase of twinning due to the growth of grains and to the release of local stresses can be hypothesized following that an important role could be played by the presence of dislocations in cell boundaries as well as oxides nano-inclusion formed in-situ during the Additive Manufacturing process (Saeidi et al., 2015) [2]. From these outcomes it is going to be presented how the 3D components produced by Additive Manufacturing could change and improve their features for potential industrial applications during life cycles and enhance such a behavior by taking carefully into account the laser parameters and its scanning speed.

Tissue Inhibitor of Metalloproteinase-2 (TIMP-2) expression is regulated by multiple neural differentiation signals

PubMed Central

Jaworski, Diane M.; Pérez-Martínez, Leonor

2010-01-01

Neuronal differentiation requires exquisitely timed cell cycle arrest for progenitors to acquire an appropriate neuronal cell fate and is achieved by communication between soluble signals, such as growth factors and extracellular matrix molecules. Here we report that the expression of TIMP-2, a matrix metalloproteinase inhibitor, is up-regulated by signals that control proliferation (bFGF and EGF) and differentiation (retinoic acid and NGF) in neural progenitor and neuroblastoma cell lines. TIMP-2 expression coincides with the appearance of neurofilament-positive neurons, indicating that TIMP-2 may play a role in neurogenesis. The up-regulation of TIMP-2 expression by proliferative signals suggests a role in the transition from proliferation to neuronal differentiation. Live labeling experiments demonstrate TIMP-2 expression only on α3 integrin-positive cells. Thus, TIMP-2 function may be mediated via interaction with integrin receptor(s). We propose that TIMP-2 represents a component of the neurogenic signaling cascade induced by mitogenic stimuli that may withdraw progenitor cells from the cell cycle permitting their terminal neuronal differentiation. PMID:16805810

Magnolol Inhibits the Growth of Non-Small Cell Lung Cancer via Inhibiting Microtubule Polymerization.

PubMed

Shen, Jia; Ma, Hailin; Zhang, Tiancheng; Liu, Hui; Yu, Linghua; Li, Guosheng; Li, Huishuang; Hu, Meichun

2017-01-01

The tubulin/microtubule system, which is an integral component of the cytoskeleton, plays an essential role in mitosis. Targeting mitotic progression by disturbing microtubule dynamics is a rational strategy for cancer treatment. Microtubule polymerization assay was performed to examine the effect of Magnolol (a novel natural phenolic compound isolated from Magnolia obovata) on cellular microtubule polymerization in human non-small cell lung cancer (NSCLC) cells. Cell cycle analysis, mitotic index assay, cell proliferation assay, colony formation assay, western blotting analysis of cell cycle regulators, Annexin V-FITC/PI staining, and live/dead viability staining were carried out to investigate the Magnolol's inhibitory effect on proliferation and viability of NSCLS cells in vitro. Xenograft model of human A549 NSCLC tumor was used to determine the Magnolol's efficacy in vivo. Magnolol treatment effectively inhibited cell proliferation and colony formation of NSCLC cells. Further study proved that Magnolol induced the mitotic phase arrest and inhibited G2/M progression in a dose-dependent manner, which were mechanistically associated with expression alteration of a series of cell cycle regulators. Furthermore, Magnolol treatment disrupted the cellular microtubule organization via inhibiting the polymerization of microtubule. We also found treatment with NSCLC cells with Magnolol resulted in apoptosis activation through a p53-independent pathway, and autophgy induction via down-regulation of the Akt/mTOR pathway. Finally, Magnolol treatment significantly suppressed the NSCLC tumor growth in mouse xenograft model in vivo. These findings identify Magnolol as a promising candidate with anti-microtubule polymerization activity for NSCLC treatment. © 2017 The Author(s). Published by S. Karger AG, Basel.

The SPF27 Homologue Num1 Connects Splicing and Kinesin 1-Dependent Cytoplasmic Trafficking in Ustilago maydis

PubMed Central

Kellner, Nikola; Heimel, Kai; Obhof, Theresa; Finkernagel, Florian; Kämper, Jörg

2014-01-01

The conserved NineTeen protein complex (NTC) is an integral subunit of the spliceosome and required for intron removal during pre-mRNA splicing. The complex associates with the spliceosome and participates in the regulation of conformational changes of core spliceosomal components, stabilizing RNA-RNA- as well as RNA-protein interactions. In addition, the NTC is involved in cell cycle checkpoint control, response to DNA damage, as well as formation and export of mRNP-particles. We have identified the Num1 protein as the homologue of SPF27, one of NTC core components, in the basidiomycetous fungus Ustilago maydis. Num1 is required for polarized growth of the fungal hyphae, and, in line with the described NTC functions, the num1 mutation affects the cell cycle and cell division. The num1 deletion influences splicing in U. maydis on a global scale, as RNA-Seq analysis revealed increased intron retention rates. Surprisingly, we identified in a screen for Num1 interacting proteins not only NTC core components as Prp19 and Cef1, but several proteins with putative functions during vesicle-mediated transport processes. Among others, Num1 interacts with the motor protein Kin1 in the cytoplasm. Similar phenotypes with respect to filamentous and polar growth, vacuolar morphology, as well as the motility of early endosomes corroborate the genetic interaction between Num1 and Kin1. Our data implicate a previously unidentified connection between a component of the splicing machinery and cytoplasmic transport processes. As the num1 deletion also affects cytoplasmic mRNA transport, the protein may constitute a novel functional interconnection between the two disparate processes of splicing and trafficking. PMID:24391515

Secondary power-producing cell. [electrodes contain same two elements in different proportions

DOEpatents

Fischer, A.K.

1971-10-26

This cell consists of an anode and a cathode containing the same two elements in different proportions and an electrolyte which contains ions of the element which is to be transported through it. The electrodes consist of chromium, iron, lithium, sodium, cadmium, copper, or zinc and phosphorus, selenium, tellurium, sulfur, arsenic, or nitrogen. A method to heat the cathode in the regeneration cycle to transfer the electronegative component to the anode is provided. (RWR)

Regenerative Fuel Cell Test Rig Completed and Operational at Glenn Research Center

NASA Technical Reports Server (NTRS)

Bents, David J.

2004-01-01

The NASA Glenn Research Center has completed construction of its first closed-cycle hydrogen-oxygen regenerative fuel cell (RFC). The RFC is an electrochemical system that collects and stores solar energy during the day then releases that energy at night, thus making the Sun's energy available all 24 hours. It consists of a dedicated hydrogen-oxygen fuel cell stack and an electrolyzer stack, the interconnecting plumbing and valves, cooling pumps, water transfer pumps, gas recirculation pumps, phase separators, storage tanks for oxygen (O2) and hydrogen (H2), heat exchangers, isolation valves, pressure regulators, nitrogen purge provisions, instrumentation, and other components. It includes all the equipment required to (1) absorb electrical power from an outside source and store it as pressurized hydrogen and oxygen and (2) make electrical power from the stored gases, saving the product water for reuse during the next cycle.

A Vitex agnus-castus extract inhibits cell growth and induces apoptosis in prostate epithelial cell lines.

PubMed

Weisskopf, M; Schaffner, W; Jundt, G; Sulser, T; Wyler, S; Tullberg-Reinert, H

2005-10-01

Extracts of Vitex agnus-castus fruits (VACF) are described to have beneficial effects on disorders related to hyperprolactinemia (cycle disorders, premenstrual syndrome). A VACF extract has recently been shown to exhibit antitumor activities in different human cancer cell lines. In the present study, we explored the antiproliferative effects of a VACF extract with a particular focus on apoptosis-inducing and potential cytotoxic effects. Three different human prostate epithelial cell lines (BPH-1, LNCaP, PC-3) representing different disease stages and androgen responsiveness were chosen. The action of VACF on cell viability was assessed using the WST-8-tetrazolium assay. Cell proliferation in cells receiving VACF alone or in combination with a pan-caspase inhibitor (Z-VAD-fmk) was quantified using a Crystal Violet assay. Flow cytometric cell cycle analysis and measurement of DNA fragmentation using an ELISA method were used for studying the induction of apoptosis. Lactate dehydrogenase (LDH) activity was determined as a marker of cytotoxicity. The extract inhibited proliferation of all three cell lines in a concentration-dependent manner with IC (50) values below 10 microg/mL after treatment for 48 h. Cell cycle analysis and DNA fragmentation assays suggest that part of the cells were undergoing apoptosis. The VACF-induced decrease in cell number was partially inhibited by Z-VAD-fmk, indicating a caspase-dependent apoptotic cell death. However, the concentration-dependent LDH activity of VACF treated cells indicated cytotoxic effects as well. These data suggest that VACF contains components that inhibit proliferation and induce apoptosis in human prostate epithelial cell lines. The extract may be useful for the prevention and/or treatment not only of benign prostatic hyperplasia but also of human prostate cancer.

3D Spatially Resolved Models of the Intracellular Dynamics of the Hepatitis C Genome Replication Cycle

PubMed Central

Reiter, Sebastian; Grillo, Alfio; Herrmann, Eva; Wittum, Gabriel

2017-01-01

Mathematical models of virus dynamics have not previously acknowledged spatial resolution at the intracellular level despite substantial arguments that favor the consideration of intracellular spatial dependence. The replication of the hepatitis C virus (HCV) viral RNA (vRNA) occurs within special replication complexes formed from membranes derived from endoplasmatic reticulum (ER). These regions, termed membranous webs, are generated primarily through specific interactions between nonstructural virus-encoded proteins (NSPs) and host cellular factors. The NSPs are responsible for the replication of the vRNA and their movement is restricted to the ER surface. Therefore, in this study we developed fully spatio-temporal resolved models of the vRNA replication cycle of HCV. Our simulations are performed upon realistic reconstructed cell structures—namely the ER surface and the membranous webs—based on data derived from immunostained cells replicating HCV vRNA. We visualized 3D simulations that reproduced dynamics resulting from interplay of the different components of our models (vRNA, NSPs, and a host factor), and we present an evaluation of the concentrations for the components within different regions of the cell. Thus far, our model is restricted to an internal portion of a hepatocyte and is qualitative more than quantitative. For a quantitative adaption to complete cells, various additional parameters will have to be determined through further in vitro cell biology experiments, which can be stimulated by the results described in the present study. PMID:28973992

Recent progress of Spectrolab high-efficiency space solar cells

NASA Astrophysics Data System (ADS)

Law, Daniel C.; Boisvert, J. C.; Rehder, E. M.; Chiu, P. T.; Mesropian, S.; Woo, R. L.; Liu, X. Q.; Hong, W. D.; Fetzer, C. M.; Singer, S. B.; Bhusari, D. M.; Edmondson, K. M.; Zakaria, A.; Jun, B.; Krut, D. D.; King, R. R.; Sharma, S. K.; Karam, N. H.

2013-09-01

Recent progress in III-V multijunction space solar cell has led to Spectrolab's GaInP/GaAs/Ge triple-junction, XTJ, cells with average 1-sun efficiency of 29% (AM0, 28°C) for cell size ranging from 59 to 72-cm2. High-efficiency inverted metamorphic (IMM) multijunction cells are developed as the next space solar cell architecture. Spectrolab's large-area IMM3J and IMM4J cells have achieved 33% and 34% 1-sun, AM0 efficiencies, respectively. The IMM3J and the IMM4J cells have both demonstrated normalized power retention of 0.86 at 5x1014 e-/cm2 fluence and 0.83 and 0.82 at 1x1015 e-/cm2 fluence post 1-MeV electron radiation, respectively. The IMM cells were further assembled into coverglass-interconnect-cell (CIC) strings and affixed to typical rigid aluminum honeycomb panels for thermal cycling characterization. Preliminary temperature cycling data of two coupons populated with IMM cell strings showed no performance degradation. Spectrolab has also developed semiconductor bonded technology (SBT) where highperformance component subcells were grown on GaAs and InP substrates separately then bonded directly to form the final multijunction cells. Large-area SBT 5-junction cells have achieved a 35.1% efficiency under 1-sun, AM0 condition.

Sq field characteristics at Phu Thuy, Vietnam, during solar cycle 23: comparisons with Sq field in other longitude sectors

NASA Astrophysics Data System (ADS)

Pham Thi Thu, H.; Amory-Mazaudier, C.; Le Huy, M.

2011-01-01

Quiet days variations in the Earth's magnetic field (the Sq current system) are compared and contrasted for the Asian, African and American sectors using a new dataset from Vietnam. This is the first presentation of the variation of the Earth's magnetic field (Sq), during the solar cycle 23, at Phu Thuy, Vietnam (geographic latitudes 21.03° N and longitude: 105.95° E). Phu Thuy observatory is located below the crest of the equatorial fountain in the Asian longitude sector of the Northern Hemisphere. The morphology of the Sq daily variation is presented as a function of solar cycle and seasons. The diurnal variation of Phu Thuy is compared to those obtained in different magnetic observatories over the world to highlight the characteristics of the Phu Thuy observations. In other longitude sectors we find different patterns. At Phu Thuy the solar cycle variation of the amplitude of the daily variation of the X component is correlated to the F.10.7 cm solar radiation (~0.74). This correlation factor is greater than the correlation factor obtained in two observatories located at the same magnetic latitudes in other longitude sectors: at Tamanrasset in the African sector (~0.42, geographic latitude ~22.79) and San Juan in the American sector (~0.03, geographic latitude ~18.38). At Phu Thuy, the Sq field exhibits an equinoctial and a diurnal asymmetry: - The seasonal variation of the monthly mean of X component exhibits the well known semiannual pattern with 2 equinox maxima, but the X component is larger in spring than in autumn. Depending of the phase of the sunspot cycle, the maximum amplitude of the X component varies in spring from 30 nT to 75 nT and in autumn from 20 nT to 60 nT. The maximum amplitude of the X component exhibits roughly the same variation in both solstices, varying from about ~20 nT to 50 nT, depending on the position into the solar cycle. - In all seasons, the mean equinoctial diurnal Y component has a morning maximum Larger than the afternoon minimum i.e. the equivalent current flow over a day is more southward than northward. During winter, the asymmetry is maximum, it erases the afternoon minimum. At the Gnangara observatory, in Asian Southern Hemisphere, the diurnal Y pattern is opposite and the current flow is more northward. It seems that in the Asian sector, the northern and southern Sq current cells both contribute strongly to the equatorial electrojet. The pattern is different in the African and American sectors where the northern Sq current cell contribution to the equatorial electrojet is smaller than the southern one. These observations can explain the unexpected maximum of amplitude of the equatorial electrojet observed in the Asian sector where the internal field is very large. During winter the Y component flow presents an anomaly, it is always southward during the whole day and there is no afternoon northward circulation.

BNIP3 contributes to the glutamine-driven aggressive behavior of melanoma cells.

PubMed

Vara-Perez, Monica; Maes, Hannelore; Van Dingenen, Sarah; Agostinis, Patrizia

2018-06-01

Aerobic glycolysis (Warburg effect) is used by cancer cells to fuel tumor growth. Interestingly, metastatic melanoma cells rely on glutaminolysis rather than aerobic glycolysis for their bioenergetic needs through the tricarboxylic acid cycle. Here, we compared the effects of glucose or glutamine on melanoma cell proliferation, migration and oxidative phosphorylation in vitro. We found that glutamine-driven melanoma cell's aggressive traits positively correlated with increased expression of HIF1α and its pro-autophagic target BNIP3. BNIP3 silencing reduced glutamine-mediated effects on melanoma cell growth, migration and bioenergetics. Hence, BNIP3 is a vital component of the mitochondria quality control required for glutamine-driven melanoma aggressiveness.

Tea Polysaccharide Prevents Colitis-Associated Carcinogenesis in Mice by Inhibiting the Proliferation and Invasion of Tumor Cells

PubMed Central

Liu, Li-Qiao; Li, Hai-Shan; Shen, Ming-Yue; Hu, Jie-Lun; Xie, Ming-Yong

2018-01-01

The imbalance between cell proliferation and apoptosis can lead to tumor progression, causing oncogenic transformation, abnormal cell proliferation and cell apoptosis suppression. Tea polysaccharide (TPS) is the major bioactive component in green tea, it has showed antioxidant, antitumor and anti-inflammatory bioactivities. In this study, the chemoprophylaxis effects of TPS on colitis-associated colon carcinogenesis, especially the cell apoptosis activation and inhibition effects on cell proliferation and invasion were analyzed. The azoxymethane/dextran sulfate sodium (AOM/DSS) was used to induce the colorectal carcinogenesis in mice. Results showed that the tumor incidence was reduced in TPS-treated AOM/DSS mice compared to AOM/DSS mice. TUNEL staining and Ki-67 immunohistochemistry staining showed that the TPS treatment increased significantly the cell apoptosis and decreased cell proliferation among AOM/DSS mice. Furthermore, TPS reduced the expression levels of the cell cycle protein cyclin D1, matrix metalloproteinase (MMP)-2, and MMP-9. In addition, in vitro studies showed that TPS, suppressed the proliferation and invasion of the mouse colon cancer cells. Overall, our findings demonstrated that TPS could be a potential agent in the treatment and/or prevention of colon tumor, which promoted the apoptosis and suppressed the proliferation and invasion of the mouse colon cancer cells via arresting cell cycle progression. PMID:29419740

Immunofluorescence Analysis of Endogenous and Exogenous Centromere-kinetochore Proteins

PubMed Central

Niikura, Yohei; Kitagawa, Katsumi

2016-01-01

"Centromeres" and "kinetochores" refer to the site where chromosomes associate with the spindle during cell division. Direct visualization of centromere-kinetochore proteins during the cell cycle remains a fundamental tool in investigating the mechanism(s) of these proteins. Advanced imaging methods in fluorescence microscopy provide remarkable resolution of centromere-kinetochore components and allow direct observation of specific molecular components of the centromeres and kinetochores. In addition, methods of indirect immunofluorescent (IIF) staining using specific antibodies are crucial to these observations. However, despite numerous reports about IIF protocols, few discussed in detail problems of specific centromere-kinetochore proteins.1-4 Here we report optimized protocols to stain endogenous centromere-kinetochore proteins in human cells by using paraformaldehyde fixation and IIF staining. Furthermore, we report protocols to detect Flag-tagged exogenous CENP-A proteins in human cells subjected to acetone or methanol fixation. These methods are useful in detecting and quantifying endogenous centromere-kinetochore proteins and Flag-tagged CENP-A proteins, including those in human cells. PMID:26967065

OAO-3 end of mission power subsystem evaluation

NASA Technical Reports Server (NTRS)

Tasevoli, M.

1982-01-01

End of mission tests were performed on the OAO-3 power subsystem in three component areas: solar array, nickel-cadmium batteries and the On-Board Processor (OBP) power boost operation. Solar array evaluation consisted of analyzing array performance characteristics and comparing them to earlier flight data. Measured solar array degradation of 14.1 to 17.7% after 8 1/3 years is in good agreement with theortical radiation damage losses. Battery discharge characteristics were compared to results of laboratory life cycle tests performed on similar cells. Comparison of cell voltage profils reveals close correlation and confirms the validity of real time life cycle simulation. The successful operation of the system in the OBP/power boost regulation mode demonstrates the excellent life, reliability and greater system utilization of power subsystems using maximum power trackers.

TRAIP promotes DNA damage response during genome replication and is mutated in primordial dwarfism

PubMed Central

Leitch, Andrea; Higgs, Martin R.; Bicknell, Louise S.; Yigit, Gökhan; Blackford, Andrew N.; Zlatanou, Anastasia; Mackenzie, Karen J.; Reddy, Kaalak; Halachev, Mihail; McGlasson, Sarah; Reijns, Martin A. M.; Fluteau, Adeline; Martin, Carol-Anne; Sabbioneda, Simone; Elcioglu, Nursel H.; Altmüller, Janine; Thiele, Holger; Greenhalgh, Lynn; Chessa, Luciana; Maghnie, Mohamad; Salim, Mahmoud; Bober, Michael B.; Nürnberg, Peter; Jackson, Stephen P.; Hurles, Matthew E.; Wollnik, Bernd; Stewart, Grant S.; Jackson, Andrew P.

2015-01-01

DNA lesions encountered by replicative polymerases threaten genome stability and cell cycle progression. Here we report the identification of mutations in TRAIP, encoding an E3 RING ubiquitin ligase, in patients with microcephalic primordial dwarfism/Seckel syndrome. We establish that TRAIP relocalizes to sites of DNA damage where it is required for optimal phosphorylation of H2AX and RPA2 during S-phase in response to UV irradiation, as well as fork progression through UV-induced DNA lesions. TRAIP is necessary for efficient cell cycle progression and mutations in TRAIP therefore limit cellular proliferation, providing a potential mechanism for microcephaly and dwarfism phenotypes. Human genetics thus identifies TRAIP as a novel component of the DNA damage response to replication-blocking DNA lesions. PMID:26595769

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Hui; Wei, Yang; Wang, Cheng

The excessive volume changes during cell cycling of Si-based anode in lithium ion batteries impeded its application. One major reason for the cell failure is particle isolation during volume shrinkage in delithiation process, which makes strong adhesion between polymer binder and anode active material particles a highly desirable property. Here, a biomimetic side-chain conductive polymer incorporating catechol, a key adhesive component of the mussel holdfast protein, was synthesized. Atomic force microscopy-based single-molecule force measurements of mussel-inspired conductive polymer binder contacting a silica surface revealed a similar adhesion toward substrate when compared with an effective Si anode binder, homo-poly(acrylic acid), withmore » the added benefit of being electronically conductive. Electrochemical experiments showed a very stable cycling of Si-alloy anodes realized via this biomimetic conducting polymer binder, leading to a high loading Si anode with a good rate performance. We attribute the ability of the Si-based anode to tolerate the volume changes during cycling to the excellent mechanical integrity afforded by the strong interfacial adhesion of the biomimetic conducting polymer.« less

In-phase oscillation of global regulons is orchestrated by a pole-specific organizer

PubMed Central

Janakiraman, Balaganesh; Mignolet, Johann; Narayanan, Sharath; Viollier, Patrick H.

2016-01-01

Cell fate determination in the asymmetric bacterium Caulobacter crescentus (Caulobacter) is triggered by the localization of the developmental regulator SpmX to the old (stalked) cell pole during the G1→S transition. Although SpmX is required to localize and activate the cell fate-determining kinase DivJ at the stalked pole in Caulobacter, in cousins such as Asticcacaulis, SpmX directs organelle (stalk) positioning and possibly other functions. We define the conserved σ54-dependent transcriptional activator TacA as a global regulator in Caulobacter whose activation by phosphorylation is indirectly down-regulated by SpmX. Using a combination of forward genetics and cytological screening, we uncover a previously uncharacterized and polarized component (SpmY) of the TacA phosphorylation control system, and we show that SpmY function and localization are conserved. Thus, SpmX organizes a site-specific, ancestral, and multifunctional regulatory hub integrating the in-phase oscillation of two global transcriptional regulators, CtrA (the master cell cycle transcriptional regulator A) and TacA, that perform important cell cycle functions. PMID:27791133

Correlation of Electrolyte Volume and Electrochemical Performance in Lithium-Ion Pouch Cells with Graphite Anodes and NMC532 Cathodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

An, Seong Jin; Li, Jianlin; Mohanty, Debasish

2017-01-01

The work herein reports on studies aimed at exploring the correlation between electrolyte volume and electrochemical performance of full cell, pouch-cells consisting of graphite/ Li 1.02Ni 0.50Mn 0.29Co 0.19O 2 (NMC-532) as the electrodes and 1.2 M LiPF6 in ethylene carbonate:ethylmethyl carbonate (EC:EMC) as the electrolyte. It is demonstrated that a minimum electrolyte volume factor of 1.9 times the total pore volume of cell components (cathode, anode, and separator) is needed for long-term cyclability and low impedance. Less electrolyte results in an increase of the measured ohmic resistances. Increased resistance ratios for charge transfer and passivation layers at cathode, relativemore » to initial values, were 1.5–2.0 after 100 cycles. At the cathode, the resistance from charge transfer was 2–3 times higher than for passivation layers. Differential voltage analysis showed that anodes were less delithiated after discharging as the cells were cycled.« less

Correlation of Electrolyte Volume and Electrochemical Performance in Lithium-Ion Pouch Cells with Graphite Anodes and NMC532 Cathodes

DOE PAGES

An, Seong Jin; Li, Jianlin; Mohanty, Debasish; ...

2017-04-07

The work herein reports on studies aimed at exploring the correlation between electrolyte volume and electrochemical performance of full cell, pouch-cells consisting of graphite/ Li 1.02Ni 0.50Mn 0.29Co 0.19O 2 (NMC-532) as the electrodes and 1.2 M LiPF 6 in ethylene carbonate:ethylmethyl carbonate (EC:EMC) as the electrolyte. In addition, it is demonstrated that a minimum electrolyte volume factor of 1.9 times the total pore volume of cell components (cathode, anode, and separator) is needed for long-term cyclability and low impedance. Less electrolyte results in an increase of the measured Ohmic resistances. Increased resistance ratios for charge transfer and passivation layersmore » at cathode, relative to initial values, were 1.5 2.0 after 100 cycles. At the cathode, the resistance from charge transfer was 2-3 times higher than for passivation layers. Lastly, differential voltage analysis showed that anodes were less delithiated after discharging as the cells were cycled.« less

Characterization of anti-leukemia components from Indigo naturalis using comprehensive two-dimensional K562/cell membrane chromatography and in silico target identification.

PubMed

Wu, Xunxun; Chen, Xiaofei; Dan, Jia; Cao, Yan; Gao, Shouhong; Guo, Zhiying; Zerbe, Philipp; Chai, Yifeng; Diao, Yong; Zhang, Lei

2016-05-06

Traditional Chinese Medicine (TCM) has been developed for thousands of years and has formed an integrated theoretical system based on a large amount of clinical practice. However, essential ingredients in TCM herbs have not been fully identified, and their precise mechanisms and targets are not elucidated. In this study, a new strategy combining comprehensive two-dimensional K562/cell membrane chromatographic system and in silico target identification was established to characterize active components from Indigo naturalis, a famous TCM herb that has been widely used for the treatment of leukemia in China, and their targets. Three active components, indirubin, tryptanthrin and isorhamnetin, were successfully characterized and their anti-leukemia effects were validated by cell viability and cell apoptosis assays. Isorhamnetin, with undefined cancer related targets, was selected for in silico target identification. Proto-oncogene tyrosine-protein kinase (Src) was identified as its membrane target and the dissociation constant (Kd) between Src and isorhamnetin was 3.81 μM. Furthermore, anti-leukemia effects of isorhamnetin were mediated by Src through inducing G2/M cell cycle arrest. The results demonstrated that the integrated strategy could efficiently characterize active components in TCM and their targets, which may bring a new light for a better understanding of the complex mechanism of herbal medicines.

Characterization of anti-leukemia components from Indigo naturalis using comprehensive two-dimensional K562/cell membrane chromatography and in silico target identification

PubMed Central

Wu, Xunxun; Chen, Xiaofei; Dan, Jia; Cao, Yan; Gao, Shouhong; Guo, Zhiying; Zerbe, Philipp; Chai, Yifeng; Diao, Yong; Zhang, Lei

2016-01-01

Traditional Chinese Medicine (TCM) has been developed for thousands of years and has formed an integrated theoretical system based on a large amount of clinical practice. However, essential ingredients in TCM herbs have not been fully identified, and their precise mechanisms and targets are not elucidated. In this study, a new strategy combining comprehensive two-dimensional K562/cell membrane chromatographic system and in silico target identification was established to characterize active components from Indigo naturalis, a famous TCM herb that has been widely used for the treatment of leukemia in China, and their targets. Three active components, indirubin, tryptanthrin and isorhamnetin, were successfully characterized and their anti-leukemia effects were validated by cell viability and cell apoptosis assays. Isorhamnetin, with undefined cancer related targets, was selected for in silico target identification. Proto-oncogene tyrosine-protein kinase (Src) was identified as its membrane target and the dissociation constant (Kd) between Src and isorhamnetin was 3.81 μM. Furthermore, anti-leukemia effects of isorhamnetin were mediated by Src through inducing G2/M cell cycle arrest. The results demonstrated that the integrated strategy could efficiently characterize active components in TCM and their targets, which may bring a new light for a better understanding of the complex mechanism of herbal medicines. PMID:27150638

A role for the ESCRT system in cell division in archaea.

PubMed

Samson, Rachel Y; Obita, Takayuki; Freund, Stefan M; Williams, Roger L; Bell, Stephen D

2008-12-12

Archaea are prokaryotic organisms that lack endomembrane structures. However, a number of hyperthermophilic members of the Kingdom Crenarchaea, including members of the Sulfolobus genus, encode homologs of the eukaryotic endosomal sorting system components Vps4 and ESCRT-III (endosomal sorting complex required for transport-III). We found that Sulfolobus ESCRT-III and Vps4 homologs underwent regulation of their expression during the cell cycle. The proteins interacted and we established the structural basis of this interaction. Furthermore, these proteins specifically localized to the mid-cell during cell division. Overexpression of a catalytically inactive mutant Vps4 in Sulfolobus resulted in the accumulation of enlarged cells, indicative of failed cell division. Thus, the archaeal ESCRT system plays a key role in cell division.

Enhancing the activity of cannabidiol and other cannabinoids in vitro through modifications to drug combinations and treatment schedules.

PubMed

Scott, Katherine Ann; Shah, Sini; Dalgleish, Angus George; Liu, Wai Man

2013-10-01

Cannabinoids are the bioactive components of the Cannabis plant that display a diverse range of therapeutic qualities. We explored the activity of six cannabinoids, used both alone and in combination in leukaemic cells. Cannabinoids were cytostatic and caused a simultaneous arrest at all phases of the cell cycle. Re-culturing pre-treated cells in drug-free medium resulted in dramatic reductions in cell viability. Furthermore, combining cannabinoids was not antagonistic. We suggest that the activities of some cannabinoids are influenced by treatment schedules; therefore, it is important to carefully select the most appropriate strategy in order to maximise their efficacy.

N-Myc down regulation induced differentiation, early cell cycle exit, and apoptosis in human malignant neuroblastoma cells having wild type or mutant p53.

PubMed

Janardhanan, Rajiv; Banik, Naren L; Ray, Swapan K

2009-11-01

Neuroblastomas, which mostly occur in children, are aggressive metastatic tumors of the sympathetic nervous system. The failure of the previous therapeutic regimens to target multiple components of N-Myc pathway resulted in poor prognosis. The present study investigated the efficacy of the combination of N-(4-hydroxyphenyl) retinamide (4-HPR, 0.5 microM) and genistein (GST, 25 microM) to control the growth of human neuroblastoma cells (SH-SY5Y and SK-N-BE2) harboring divergent molecular attributes. Combination of 4-HPR and GST down regulated N-Myc, Notch-1, and Id2 to induce neuronal differentiation. Transition to neuronal phenotype was accompanied by increase in expression of e-cadherin. Induction of neuronal differentiation was associated with decreased expression of hTERT, PCNA, survivin, and fibronectin. This is the first report that combination of 4-HPR and GST mediated reactivation of multiple tumor suppressors (p53, p21, Rb, and PTEN) for early cell cycle exit (due to G1/S phase arrest) in neuroblastoma cells. Reactivation of tumor suppressor(s) repressed N-Myc driven growth factor mediated angiogenic and invasive pathways (VEGF, b-FGF, MMP-2, and MMP-9) in neuroblastoma. Repression of angiogenic factors led to the blockade of components of mitogenic pathways [phospho-Akt (Thr 308), p65 NF-kappaB, and p42/44 Erk 1/2]. Taken together, the combination of 4-HPR and GST effectively blocked survival, mitogenic, and angiogenic pathways and activated proteases for apoptosis in neuroblastoma cells. These results suggested that combination of 4-HPR and GST could be effective for controlling the growth of heterogeneous human neuroblastoma cell populations.

Cyclin C influences the timing of mitosis in fission yeast.

PubMed

Banyai, Gabor; Szilagyi, Zsolt; Baraznenok, Vera; Khorosjutina, Olga; Gustafsson, Claes M

2017-07-01

The multiprotein Mediator complex is required for the regulated transcription of nearly all RNA polymerase II-dependent genes. Mediator contains the Cdk8 regulatory subcomplex, which directs periodic transcription and influences cell cycle progression in fission yeast. Here we investigate the role of CycC, the cognate cyclin partner of Cdk8, in cell cycle control. Previous reports suggested that CycC interacts with other cellular Cdks, but a fusion of CycC to Cdk8 reported here did not cause any obvious cell cycle phenotypes. We find that Cdk8 and CycC interactions are stabilized within the Mediator complex and the activity of Cdk8-CycC is regulated by other Mediator components. Analysis of a mutant yeast strain reveals that CycC, together with Cdk8, primarily affects M-phase progression but mutations that release Cdk8 from CycC control also affect timing of entry into S phase. © 2017 Banyai et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

Cell-cycle regulation of formin-mediated actin cable assembly

PubMed Central

Miao, Yansong; Wong, Catherine C. L.; Mennella, Vito; Michelot, Alphée; Agard, David A.; Holt, Liam J.; Yates, John R.; Drubin, David G.

2013-01-01

Assembly of appropriately oriented actin cables nucleated by formin proteins is necessary for many biological processes in diverse eukaryotes. However, compared with knowledge of how nucleation of dendritic actin filament arrays by the actin-related protein-2/3 complex is regulated, the in vivo regulatory mechanisms for actin cable formation are less clear. To gain insights into mechanisms for regulating actin cable assembly, we reconstituted the assembly process in vitro by introducing microspheres functionalized with the C terminus of the budding yeast formin Bni1 into extracts prepared from yeast cells at different cell-cycle stages. EM studies showed that unbranched actin filament bundles were reconstituted successfully in the yeast extracts. Only extracts enriched in the mitotic cyclin Clb2 were competent for actin cable assembly, and cyclin-dependent kinase 1 activity was indispensible. Cyclin-dependent kinase 1 activity also was found to regulate cable assembly in vivo. Here we present evidence that formin cell-cycle regulation is conserved in vertebrates. The use of the cable-reconstitution system to test roles for the key actin-binding proteins tropomyosin, capping protein, and cofilin provided important insights into assembly regulation. Furthermore, using mass spectrometry, we identified components of the actin cables formed in yeast extracts, providing the basis for comprehensive understanding of cable assembly and regulation. PMID:24133141

S100A6 regulates endothelial cell cycle progression by attenuating antiproliferative STAT1 signaling

PubMed Central

Lerchenmüller, Carolin; Heißenberg, Julian; Damilano, Federico; Bezzeridis, Vassilios J.; Krämer, Isabel; Bochaton-Piallat, Marie-Luce; Hirschberg, Kristóf; Busch, Martin; Katus, Hugo A.; Peppel, Karsten; Rosenzweig, Anthony; Busch, Hauke; Boerries, Melanie; Most, Patrick

2016-01-01

Objective S100A6, a member of the S100-protein family, has been described as relevant for cell cycle entry and progression in endothelial cells (ECs). The molecular mechanism conferring S100A6’s proliferative actions, however, remained elusive. Approach and Results Originating from the clinically relevant observation of enhanced S100A6 protein expression in proliferating ECs in remodeling coronary and carotid arteries, our study unveiled S100A6 as a suppressor of antiproliferative signal transducers and activators of transcription 1 (STAT1) signaling. Discovery of the molecular liaison was enabled by combining gene expression time series analysis with bioinformatic pathway modeling in S100A6 silenced human ECs stimulated with vascular endothelial growth factor A (VEGF-A). This unbiased approach led to successful identification and experimental validation of interferon-inducible transmembrane protein 1 (IFITM1) and protein inhibitors of activated STAT (PIAS) as key components of the link between S100A6 and STAT1. Conclusions Given the important role of coordinated EC cell cycle activity for integrity and reconstitution of the inner lining of arterial blood vessels in health and disease, STAT1 suppression by S100A6 may represent a promising therapeutic target to facilitate reendothelialization in damaged vessels. PMID:27386938

Licorice infusion: Chemical profile and effects on the activation and the cell cycle progression of human lymphocytes

PubMed Central

Cheel, José; Onofre, Gabriela; Vokurkova, Doris; Tůmová, Lenka; Neugebauerová, Jarmila

2010-01-01

A licorice infusion (LI) and its major constituents were investigated for their capacity to stimulate the activation and the cell cycle progression of human lymphocytes, measured by the CD69 expression and DNA content, respectively. The chemical profile of LI was determined by high-performance liquid chromatography-diode array detection (HPLC-DAD). Results: Two major components of LI were identified as liquiritin (1) and glycyrrhizin (2); total flavones and flavonols were shown as its minor constituents. The LI (100-800 μg/ml) stimulated the expression of CD69 on lymphocytes in a concentration-independent manner. Values of the activation index (AI) of total lymphocytes treated with LI (100-800 μg/ml) did not differ significantly among them (P < 0.05), but were 50% lower than the AI value exhibited by cells treated with phytohemagglutinin (PHA). The LI showed a similar effect on T cells, but on a lower scale. Compounds 1 and 2 (12-100 μg/ml) did not stimulate the CD69 expression on lymphocytes. The LI, 1 and 2 showed no meaningful effect on cell cycle progression of lymphocytes. The experimental data indicates that LI stimulates the activation of lymphocytes as a result of a proliferation-independent process. This finding suggests that LI could be considered as a potential specific immune stimulator. PMID:20548933

Transactivation mediated by B-Myb is dependent on TAF(II)250.

PubMed

Bartusel, Thorsten; Klempnauer, Karl-Heinz

2003-05-15

B-Myb is a highly conserved member of the Myb family of transcription factors, which has been implicated in cell cycle regulation. B-Myb is expressed in most proliferating cells and its activity is highly regulated around the G1/S-phase border of the cell cycle. It is generally assumed that B-Myb regulates the expression of genes that are crucial for cell proliferation; however, the identity of these genes, the molecular mechanisms by which B-Myb stimulates their expression and the involvement of other proteins have not been sufficiently clarified. We have employed the hamster cell line ts13 as a tool to demonstrate a functional link between B-Myb and the coactivator TAF(II)250, a key component of the transcriptional machinery which itself is essential for cell proliferation. ts13 cells express a point-mutated version of TAF(II)250 whose intrinsic histone acetyl transferase activity is temperature sensitive. Transactivation of Myb-responsive reporter genes by B-Myb is temperature-dependent in ts13 cells but not in ts13 cells, which have been rescued by transfection with an expression vector for wild-type TAF(II)250. Furthermore, B-Myb and TAF(II)250 can be coprecipitated, suggesting that both proteins are present in a complex. The formation of this complex is dependent on the DNA-binding domain of B-Myb and not on its transactivation domain. Taken together, these observations provide the first evidence that the coactivator TAF(II)250 is involved in the activation of Myb responsive promoters by B-Myb. The finding that B-Myb transactivation is dependent on a key coactivator involved in cell cycle control is consistent with and strengthens the idea that B-Myb plays a crucial role as a transcription factor in proliferating cells.

Functional characterization of Anaphase Promoting Complex/Cyclosome (APC/C) E3 ubiquitin ligases in tumorigenesis

PubMed Central

Zhang, Jinfang; Wan, Lixin; Dai, Xiangpeng; Sun, Yi; Wei, Wenyi

2014-01-01

The Anaphase Promoting Complex/Cyclosome (APC/C) is a multi-subunit E3 ubiquitin ligase that primarily governs cell cycle progression. APC/C is composed of at least 14 core subunits and recruits its substrates for ubiquitination via one of the two adaptor proteins, Cdc20 or Cdh1, in M or M/early G1 phase, respectively. Furthermore, recent studies have shed light on crucial functions for APC/C in maintaining genomic integrity, neuronal differentiation, cellular metabolism and tumorigenesis. To gain better insight into the in vivo physiological functions of APC/C in regulating various cellular processes, particularly development and tumorigenesis, a number of mouse models of APC/C core subunits, coactivators or inhibitors have been established and characterized. However, due to their essential role in cell cycle regulation, most of the germline knockout mice targeting the APC/C pathway are embryonic lethal, indicating the need for generating conditional knockout mouse models to assess the role in tumorigenesis for each APC/C signaling component in specific tissues. In this review, we will first provide a brief introduction of the ubiquitin-proteasome system (UPS) and the biochemical activities and cellular functions of the APC/C E3 ligase. We will then focus primarily on characterizing genetic mouse models used to understand the physiological roles of each APC/C signaling component in embryogenesis, cell proliferation, development and carcinogenesis. Finally, we discuss future research directions to further elucidate the physiological contributions of APC/C components during tumorigenesis and validate their potentials as a novel class of anti-cancer targets. PMID:24569229

Lignin: Characterization of a Multifaceted Crop Component

PubMed Central

2013-01-01

Lignin is a plant component with important implications for various agricultural disciplines. It confers rigidity to cell walls, and is therefore associated with tolerance to abiotic and biotic stresses and the mechanical stability of plants. In animal nutrition, lignin is considered an antinutritive component of forages as it cannot be readily fermented by rumen microbes. In terms of energy yield from biomass, the role of lignin depends on the conversion process. It contains more gross energy than other cell wall components and therefore confers enhanced heat value in thermochemical processes such as direct combustion. Conversely, it negatively affects biological energy conversion processes such as bioethanol or biogas production, as it inhibits microbial fermentation of the cell wall. Lignin from crop residues plays an important role in the soil organic carbon cycling, as it constitutes a recalcitrant carbon pool affecting nutrient mineralization and carbon sequestration. Due to the significance of lignin in several agricultural disciplines, the modification of lignin content and composition by breeding is becoming increasingly important. Both mapping of quantitative trait loci and transgenic approaches have been adopted to modify lignin in crops. However, breeding goals must be defined considering the conflicting role of lignin in different agricultural disciplines. PMID:24348159

Ecology and thermal inactivation of microbes in and on interplanetary space vehicle components. [examined with a scanning electron microscope

NASA Technical Reports Server (NTRS)

Campbell, J. E.

1974-01-01

The uses of scanning electron microscopy in assessing changes that occur in spores exposed to wet and dry heat cycles at elevated temperatures were examined. Several species of Bacillus and other nonspore-forming species of organisms were used for the experiment. Surface morphology of viable and nonviable organisms was clearly detectable by this method, making it a potentially useful technique for investigating microbial inactivation on space vehicle surfaces and components. Micrographs of the spores and bacterial cells are provided.

Shaping the Flavivirus Replication Complex: It's Curvaceous!

PubMed

Aktepe, Turgut E; Mackenzie, Jason M

2018-06-22

Flavivirus replication is intimately involved with remodelled membrane organelles that are compartmentalised for different functions during their life cycle. Recent advances in lipid analyses and gene depletion have identified a number of host components that enable efficient virus replication in infected cells. Here we describe the current understanding on the role and contribution of host lipids and membrane bending proteins to flavivirus replication, with a particular focus on the components that bend and shape the membrane bilayer to induce the flavivirus-induced organelles characteristic of infection. This article is protected by copyright. All rights reserved.

Middle Infrared Radiation Induces G2/M Cell Cycle Arrest in A549 Lung Cancer Cells

PubMed Central

Huang, Hsuan-Cheng; Tsai, Shang-Ru; Juan, Hsueh-Fen; Lee, Si-Chen

2013-01-01

There were studies investigating the effects of broadband infrared radiation (IR) on cancer cell, while the influences of middle-infrared radiation (MIR) are still unknown. In this study, a MIR emitter with emission wavelength band in the 3–5 µm region was developed to irradiate A549 lung adenocarcinoma cells. It was found that MIR exposure inhibited cell proliferation and induced morphological changes by altering the cellular distribution of cytoskeletal components. Using quantitative PCR, we found that MIR promoted the expression levels of ATM (ataxia telangiectasia mutated), ATR (ataxia-telangiectasia and Rad3-related and Rad3-related), TP53 (tumor protein p53), p21 (CDKN1A, cyclin-dependent kinase inhibitor 1A) and GADD45 (growth arrest and DNA-damage inducible), but decreased the expression levels of cyclin B coding genes, CCNB1 and CCNB2, as well as CDK1 (Cyclin-dependent kinase 1). The reduction of protein expression levels of CDC25C, cyclin B1 and the phosphorylation of CDK1 at Thr-161 altogether suggest G2/M arrest occurred in A549 cells by MIR. DNA repair foci formation of DNA double-strand breaks (DSB) marker γ-H2AX and sensor 53BP1 was induced by MIR treatment, it implies the MIR induced G2/M cell cycle arrest resulted from DSB. This study illustrates a potential role for the use of MIR in lung cancer therapy by initiating DSB and blocking cell cycle progression. PMID:23335992

Treatment of mcf-7 breast cancer cells with a red grape wine polyphenol fraction results in disruption of calcium homeostasis and cell cycle arrest causing selective cytotoxicity.

PubMed

Hakimuddin, Fatima; Paliyath, Gopinadhan; Meckling, Kelly

2006-10-04

Food components influence the physiology by modulating gene expression and biochemical pathways within the human body. The disease-preventive roles of several fruit and vegetable components have been related to such properties. Polyphenolic components such as flavonoids are strong antioxidants and induce the expression of several xenobiotic-detoxifying enzymes. The mechanism of selective cytotoxicity induced by red grape wine polyphenols against MCF-7 breast cancer cells was investigated in relation to their interference with calcium homeostasis. MCF-7 cells showed an increase in cytosolic calcium levels within 10 min of treatment with the polyphenols. Immunohistochemical localization of calmodulin with secondary gold-labeled antibodies showed similar levels of gold labeling in both MCF-7 cells and the spontaneously immortalized, normal MCF-10A cell line. MCF-7 cells treated with the red wine polyphenol fraction (RWPF) showed swelling of endoplasmic reticulum, dissolution of the nucleus, and loss of plasma membrane integrity as well as reduced mitochondrial membrane potential. These cells were arrested at the G2/M interphase. By contrast, MCF-10A cells did not show such changes after RWPF treatment. The results suggest that polyphenol-induced calcium release may disrupt mitochondrial function and cause membrane damage, resulting in selective cytotoxicity toward MCF-7 cells. This property could further be developed toward breast cancer prevention strategies either independently or in conjunction with conventional prevention therapies where a positive drug-nutrient interaction can be demonstrated.

Glassy materials for lithium batteries: electrochemical properties and devices performances

NASA Astrophysics Data System (ADS)

Duclot, Michel; Souquet, Jean-Louis

Amorphous or glassy materials may be used as electrolyte or electrode materials for lithium primary or secondary batteries. A first generation proceeded from classical coin cells in which the organic electrolyte was replaced by a high lithium conductive glassy electrolyte. The solid components were assembled under isostatic pressure. The main advantages of such cells are a good storage stability and ability to operate until 200°C. Nevertheless, the high resistivity of the glassy electrolyte below room temperature and a limited depth for charge and discharge cycles makes these cells not competitive compared to conventional lithium-ion batteries. More promising, are the thin films solid state microbatteries realised by successive depositions of electrodes and electrolyte. The low resistance of the electrolyte amorphous layer allows cycling at temperatures as low as -10°C. The total thickness of thin film batteries, including packaging is less than 100 μm. A capacity of about 100 μAh cm -2 with over 10 4 charge-discharge cycles at 90% in depth of discharge is well suited for energy independent smart cards or intelligent labels, which represent for these devices a large and unrivalled market.

MAP/microtubule affinity-regulating kinases, microtubule dynamics, and spermatogenesis.

PubMed

Tang, Elizabeth I; Mruk, Dolores D; Cheng, C Yan

2013-05-01

During spermatogenesis, spermatids derived from meiosis simultaneously undergo extensive morphological transformation, to become highly specialized and metabolically quiescent cells, and transport across the seminiferous epithelium. Spermatids are also transported back-and-forth across the seminiferous epithelium during the epithelial cycle until they line up at the luminal edge of the tubule to prepare for spermiation at stage VIII of the cycle. Spermatid transport thus requires the intricate coordination of the cytoskeletons in Sertoli cells (SCs) as spermatids are nonmotile cells lacking the ultrastructures of lamellipodia and filopodia, as well as the organized components of the cytoskeletons. In the course of preparing this brief review, we were surprised to see that, except for some earlier eminent morphological studies, little is known about the regulation of the microtubule (MT) cytoskeleton and the coordination of MT with the actin-based cytoskeleton to regulate spermatid transport during the epithelia cycle, illustrating that this is a largely neglected area of research in the field. Herein, we summarize recent findings in the field regarding the significance of actin- and tubulin-based cytoskeletons in SCs that support spermatid transport; we also highlight specific areas of research that deserve attention in future studies.

A comparison between molten carbonate fuel cells based hybrid systems using air and supercritical carbon dioxide Brayton cycles with state of the art technology

NASA Astrophysics Data System (ADS)

Sánchez, D.; Muñoz de Escalona, J. M.; Chacartegui, R.; Muñoz, A.; Sánchez, T.

A proposal for high efficiency hybrid systems based on molten carbonate fuel cells is presented in this paper. This proposal is based on adopting a closed cycle bottoming gas turbine using supercritical carbon dioxide as working fluid as opposed to open cycle hot air turbines typically used in this type of power generators. First, both bottoming cycles are compared for the same operating conditions, showing that their performances do not differ as much as initially expected, even if the initial objective of reducing compression work is accomplished satisfactorily. In view of these results, a profound review of research and industrial literature is carried out in order to determine realistic specifications for the principal components of the bottoming systems. From this analysis, it is concluded that an appropriate set of specifications must be developed for each bottoming cycle as the performances of compressor, turbine and recuperator differ significantly from one working fluid to another. Thus, when the operating conditions are updated, the performances of the resulting systems show a remarkable advantage of carbon dioxide based systems over conventional air units. Actually, the proposed hybrid system shows its capability to achieve 60% net efficiency, what represents a 10% increase with respect to the reference system.

T Cells Encountering Myeloid Cells Programmed for Amino Acid-dependent Immunosuppression Use Rictor/mTORC2 Protein for Proliferative Checkpoint Decisions*

PubMed Central

Van de Velde, Lee-Ann; Subramanian, Chitra; Smith, Amber M.; Barron, Luke; Qualls, Joseph E.; Neale, Geoffrey; Alfonso-Pecchio, Adolfo; Jackowski, Suzanne; Rock, Charles O.; Wynn, Thomas A.; Murray, Peter J.

2017-01-01

Modulation of T cell proliferation and function by immunoregulatory myeloid cells are an essential means of preventing self-reactivity and restoring tissue homeostasis. Consumption of amino acids such as arginine and tryptophan by immunoregulatory macrophages is one pathway that suppresses local T cell proliferation. Using a reduced complexity in vitro macrophage-T cell co-culture system, we show that macrophage arginase-1 is the only factor required by M2 macrophages to block T cells in G1, and this effect is mediated by l-arginine elimination rather than metabolite generation. Tracking how T cells adjust their metabolism when deprived of arginine revealed the significance of macrophage-mediated arginine deprivation to T cells. We found mTORC1 activity was unaffected in the initial G1 block. After 2 days of arginine deprivation, mTORC1 activity declined paralleling a selective down-regulation of SREBP target gene expression, whereas mRNAs involved in glycolysis, gluconeogenesis, and T cell activation were unaffected. Cell cycle arrest was reversible at any point by exogenous arginine, suggesting starved T cells remain poised awaiting nutrients. Arginine deprivation-induced cell cycle arrest was mediated in part by Rictor/mTORC2, providing evidence that this nutrient recognition pathway is a central component of how T cells measure environmental arginine. PMID:27903651

T Cells Encountering Myeloid Cells Programmed for Amino Acid-dependent Immunosuppression Use Rictor/mTORC2 Protein for Proliferative Checkpoint Decisions.

PubMed

Van de Velde, Lee-Ann; Subramanian, Chitra; Smith, Amber M; Barron, Luke; Qualls, Joseph E; Neale, Geoffrey; Alfonso-Pecchio, Adolfo; Jackowski, Suzanne; Rock, Charles O; Wynn, Thomas A; Murray, Peter J

2017-01-06

Modulation of T cell proliferation and function by immunoregulatory myeloid cells are an essential means of preventing self-reactivity and restoring tissue homeostasis. Consumption of amino acids such as arginine and tryptophan by immunoregulatory macrophages is one pathway that suppresses local T cell proliferation. Using a reduced complexity in vitro macrophage-T cell co-culture system, we show that macrophage arginase-1 is the only factor required by M2 macrophages to block T cells in G 1 , and this effect is mediated by l-arginine elimination rather than metabolite generation. Tracking how T cells adjust their metabolism when deprived of arginine revealed the significance of macrophage-mediated arginine deprivation to T cells. We found mTORC1 activity was unaffected in the initial G 1 block. After 2 days of arginine deprivation, mTORC1 activity declined paralleling a selective down-regulation of SREBP target gene expression, whereas mRNAs involved in glycolysis, gluconeogenesis, and T cell activation were unaffected. Cell cycle arrest was reversible at any point by exogenous arginine, suggesting starved T cells remain poised awaiting nutrients. Arginine deprivation-induced cell cycle arrest was mediated in part by Rictor/mTORC2, providing evidence that this nutrient recognition pathway is a central component of how T cells measure environmental arginine. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

A radially accessible tubular in situ X-ray cell for spatially resolved operando scattering and spectroscopic studies of electrochemical energy storage devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Hao; Allan, Phoebe K.; Borkiewicz, Olaf J.

2016-09-16

A tubularoperandoelectrochemical cell has been developed to allow spatially resolved X-ray scattering and spectroscopic measurements of individual cell components, or regions thereof, during device operation. These measurements are enabled by the tubular cell geometry, wherein the X-ray-transparent tube walls allow radial access for the incident and scattered/transmitted X-ray beam; by probing different depths within the electrode stack, the transformation of different components or regions can be resolved. The cell is compatible with a variety of synchrotron-based scattering, absorption and imaging methodologies. The reliability of the electrochemical cell and the quality of the resulting X-ray scattering and spectroscopic data are demonstratedmore » for two types of energy storage: the evolution of the distribution of the state of charge of an Li-ion battery electrode during cycling is documented using X-ray powder diffraction, and the redistribution of ions between two porous carbon electrodes in an electrochemical double-layer capacitor is documented using X-ray absorption near-edge spectroscopy.« less

More antitumor efficacy of the PI3K inhibitor GDC-0941 in breast cancer with PIK3CA mutation or HER2 amplification status in vitro.

PubMed

Zheng, Jie; Wang, Huan; Yao, Jia; Zou, Xianjin

2014-01-01

PIK3CA is probably the most commonly mutated kinase in several malignant tumors. Activation of class I phosphatidylinositol 3' kinase (PI3K) regulates tumor proliferation, survival, etc. This study sought to identify whether the pan-inhibitor has more antitumor efficacy in breast cancer cells with PIK3CA Mutation or HER2 amplification than basal-like cancer cells. The proliferation of breast cancer cells was measured by MTT assay in the presence of GDC-0941. Afterwards, we determined the visible changes in signaling in the PI3K/AKT/mTOR pathway. Finally, we examined GDC-0941 effects on cell cycle, apoptosis and motility. GDC-0941 exhibited excellent inhibition on three cell lines with PIK3CA mutation or HER2 amplification. In addition, GDC-0941 resulted in decreased Akt activity. GDC-0941 downregulated the key components of the cell cycle machinery, such as cyclin D1, upregulated the apoptotic markers and inhibited cell motility on three cell lines with PIK3CA Mutation or HER2 amplification. Antitumor activity of GDC-0941 treatment amongst tumor cell lines with PIK3CA mutation and HER2 amplification may have clinical utility in patients with these oncogenic alterations.

Casein kinase 2 and the cell response to growth factors.

PubMed

Filhol-Cochet, O; Loue-Mackenbach, P; Cochet, C; Chambaz, E M

1994-01-01

Different approaches have been followed with the aim of delineating a possible role of casein kinase 2 (CK2) in the mitogenic signalling in response to cell growth factors. (a) Immunocytochemical detection of CK2 showed that while the kinase is evenly distributed throughout cycle arrested cells, it becomes preferentially associated with the nuclear compartment in activity growing cells; (b) CK2 biosynthesis is activated as an early response of quiescent cells to growth factors. The newly synthesized CK2 steadily accumulates as the cells progress through the G1 phase. This growth factor-induced CK2 biosynthesis involves in parallel the two alpha and beta subunits of the kinase, with no detectable preferential subcellular localization of the newly synthesized enzyme; and (c) In addition to substrate phosphorylation, CK2 may form molecular complexes with cell components of functional significance. Such is the case with the protein p53, a major negative regulator of the cell cycle. CK2 forms a high affinity association (Kd 70 nM) with p53, through its beta subunit. The complex dissociates in the presence of adenosine triphosphate (ATP). These observations suggest that CK2 and p53 may play a coordinated regulatory role in the cell response to growth factors.

Cell module and fuel conditioner

NASA Technical Reports Server (NTRS)

Hoover, D. Q., Jr.

1980-01-01

The computer code for the detailed analytical model of the MK-2 stacks is described. An ERC proprietary matrix is incorporated in the stacks. The mechanical behavior of the stack during thermal cycles under compression was determined. A 5 cell stack of the MK-2 design was fabricated and tested. Designs for the next three stacks were selected and component fabrication initiated. A 3 cell stack which verified the use of wet assembly and a new acid fill procedure were fabricated and tested. Components for the 2 kW test facility were received or fabricated and construction of the facility is underway. The definition of fuel and water is used in a study of the fuel conditioning subsystem. Kinetic data on several catalysts, both crushed and pellets, was obtained in the differential reactor. A preliminary definition of the equipment requirements for treating tap and recovered water was developed.

Diffusion welding of Cassegrainian concentrator cell stack assemblies. M.S. Thesis Final Report, Jun. 1983 - Sep. 1985

NASA Technical Reports Server (NTRS)

Gangl, K. J.

1985-01-01

Development of a procedure to join the components of the Cassegrainian concentrator photovoltaic cell stack assembly was studied. Diffusion welding was selected as the most promising process, and was concentrated on exclusively. All faying surfaces were coated with silver to promote welding. The first phase of the study consisted of developing the relationship between process parameters and joint strength using silver plated steel samples and an isostatic pressure system. In the second phase, mockups of the cell stack assembly were welded in a hot isostatic press. Excellent joint strength was achieved with parameters of 350 C and 10 ksi, but the delicate GaAs component could not survive the welding cycle without cracking. The tendency towards cracking was found to be affected by both temperature and pressure. Further work will be required in the future to solve this problem.

Carnosic acid inhibits the growth of ER-negative human breast cancer cells and synergizes with curcumin.

PubMed

Einbond, Linda Saxe; Wu, Hsan-Au; Kashiwazaki, Ryota; He, Kan; Roller, Marc; Su, Tao; Wang, Xiaomei; Goldsberry, Sarah

2012-10-01

Studies indicate that extracts and purified components, including carnosic acid, from the herb rosemary display significant growth inhibitory activity on a variety of cancers. This paper examines the ability of rosemary/carnosic acid to inhibit the growth of human breast cancer cells and to synergize with curcumin. To do this, we treated human breast cancer cells with rosemary/carnosic acid and assessed effects on cell proliferation, cell cycle distribution, gene expression patterns, activity of the purified Na/K ATPase and combinations with curcumin. Rosemary/carnosic acid potently inhibits proliferation of ER-negative human breast cancer cells and induces G1 cell cycle arrest. Further, carnosic acid is selective for MCF7 cells transfected for Her2, indicating that Her2 may function in its action. To reveal primary effects, we treated ER-negative breast cancer cells with carnosic acid for 6h. At a low dose, 5 μg/ml (15 μM), carnosic acid activated the expression of 3 genes, induced through the presence of antioxidant response elements, including genes involved in glutathione biosynthesis (CYP4F3, GCLC) and transport (SLC7A11). At a higher dose, 20 μg/ml, carnosic acid activated the expression of antioxidant (AKR1C2, TNXRD1, HMOX1) and apoptosis (GDF15, PHLDA1, DDIT3) genes and suppressed the expression of inhibitor of transcription (ID3) and cell cycle (CDKN2C) genes. Carnosic acid exhibits synergy with turmeric/curcumin. These compounds inhibited the activity of the purified Na-K-ATPase which may contribute to this synergy. Rosemary/carnosic acid, alone or combined with curcumin, may be useful to prevent and treat ER-negative breast cancer. Copyright © 2012 Elsevier B.V. All rights reserved.

Up-regulation of tumor suppressor carcinoembryonic antigen-related cell adhesion molecule 1 in human colon cancer Caco-2 cells following repetitive exposure to dietary levels of a polyphenol-rich chokeberry juice.

PubMed

Bermúdez-Soto, María J; Larrosa, Mar; Garcia-Cantalejo, Jesús M; Espín, Juan C; Tomás-Barberan, Francisco A; García-Conesa, María T

2007-04-01

Consumption of berries and red fruits rich in polyphenols may contribute to the reduction of colon cancer through mechanisms not yet understood. In this study, we investigated the response of subconfluent Caco-2 cells (a human colon carcinoma model) to repetitive exposure (2 h a day for a 4-day period) of a subtoxic dose of a chokeberry (Aronia melanocarpa) juice containing mixed polyphenols. To mimic physiological conditions, we subjected the chokeberry juice to in vitro gastric and pancreatic digestion. The effects on viability, proliferation and cell cycle were determined, and changes in the expression of genes in response to the chokeberry treatment were screened using Affymetrix oligonucleotide microarrays. Exposure to the chokeberry juice inhibited Caco-2 cell proliferation by causing G(2)/M cell cycle arrest. We detected changes in the expression of a group of genes involved in cell growth and proliferation and cell cycle regulation, as well as those associated to colorectal cancer. A selection of these genes was further confirmed by quantitative RT-PCR. Among these, the tumor suppressor carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1), whose expression is known to be reduced in the majority of early adenomas and carcinomas, was up-regulated by the treatment both at the mRNA and protein levels (as shown by flow cytometry analysis). CEACAM1, with a significant regulatory role on cell proliferation of particular interest at early stages of cancer development, may be a potential target for chemoprevention by food components such as those present in polyphenol-rich fruits.

Advances in ambient temperature secondary lithium cells

NASA Technical Reports Server (NTRS)

Subbarao, S.; Shen, D. H.; Deligiannis, F.; Huang, C-K.; Halpert, G.

1989-01-01

The Jet Propulsion Laboratory is involved in a Research and Development program sponsored by NASA/OAST on the development of ambient temperature secondary lithium cells for future space applications. Some of the projected applications are planetary spacecraft, planetary rovers, and astronaut equipment. The main objective is to develop secondary lithium cells with greater than 100 Wh/kg specific energy while delivering 1000 cycles at 50 percent Depth of Discharge (DOD). To realize these ambitious goals, the work was initially focused on several important basic issues related to the cell chemistry, selection of cathode materials and electrolytes, and component development. The performance potential of Li-TiS2, Li-MoS3, Li-V6O13 and Li-NbSe3 electrochemical systems was examined. Among these four, the Li-TiS2 system was found to be the most promising system in terms of realizable specific energy and cycle life. Some of the major advancements made so far in the development of Li-TiS2 cells are in the areas of cathode processing technology, mixed solvent electrolytes, and cell assembly. Methods were developed for the fabrication of large size high performance TiS2 cathodes. Among the various electrolytes examined, 1.5M LiAsF6/EC + 2-MeTHF mixed solvent electrolyte was found to be more stable towards lithium. Experimental cells activated with this electrolyte exhibited more than 300 cycles at 100 percent Depth of Discharge. Work is in progress in other areas such as selection of lithium alloys as candidate anode materials, optimization of cell design, and development of 5 Ah cells. The advances made at the Jet Propulsion Laboratory on the development of secondary lithium cells are summarized.

The Malleable Nature of the Budding Yeast Nuclear Envelope: Flares, Fusion, and Fenestrations.

PubMed

Meseroll, Rebecca A; Cohen-Fix, Orna

2016-11-01

In eukaryotes, the nuclear envelope (NE) physically separates nuclear components and activities from rest of the cell. The NE also provides rigidity to the nucleus and contributes to chromosome organization. At the same time, the NE is highly dynamic; it must change shape and rearrange its components during development and throughout the cell cycle, and its morphology can be altered in response to mutation and disease. Here we focus on the NE of budding yeast, Saccharomyces cerevisiae, which has several unique features: it remains intact throughout the cell cycle, expands symmetrically during interphase, elongates during mitosis and, expands asymmetrically during mitotic delay. Moreover, its NE is safely breached during mating and when large structures, such as nuclear pore complexes and the spindle pole body, are embedded into its double membrane. The budding yeast NE lacks lamins and yet the nucleus is capable of maintaining a spherical shape throughout interphase. Despite these eccentricities, studies of the budding yeast NE have uncovered interesting, and likely conserved, processes that contribute to NE dynamics. In particular, we discuss the processes that drive and enable NE expansion and the dramatic changes in the NE that lead to extensions and fenestrations. J. Cell. Physiol. 231: 2353-2360, 2016. Published 2016. This article is a U.S. Government work and is in the public domain in the USA. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

Centromeric chromatin and its dynamics in plants.

PubMed

Lermontova, Inna; Sandmann, Michael; Mascher, Martin; Schmit, Anne-Catherine; Chabouté, Marie-Edith

2015-07-01

Centromeres are chromatin structures that are required for proper separation of chromosomes during mitosis and meiosis. The centromere is composed of centromeric DNA, often enriched in satellite repeats, and kinetochore complex proteins. To date, over 100 kinetochore components have been identified in various eukaryotes. Kinetochore assembly begins with incorporation of centromeric histone H3 variant CENH3 into centromeric nucleosomes. Protein components of the kinetochore are either present at centromeres throughout the cell cycle or localize to centromeres transiently, prior to attachment of microtubules to each kinetochore in prometaphase of mitotic cells. This is the case for the spindle assembly checkpoint (SAC) proteins in animal cells. The SAC complex ensures equal separation of chromosomes between daughter nuclei by preventing anaphase onset before metaphase is complete, i.e. the sister kinetochores of all chromosomes are attached to spindle fibers from opposite poles. In this review, we focus on the organization of centromeric DNA and the kinetochore assembly in plants. We summarize recent advances regarding loading of CENH3 into the centromere, and the subcellular localization and protein-protein interactions of Arabidopsis thaliana proteins involved in kinetochore assembly and function. We describe the transcriptional activity of corresponding genes based on in silico analysis of their promoters and cell cycle-dependent expression. Additionally, barley homologs of all selected A. thaliana proteins have been identified in silico, and their sequences and domain structures are presented. © 2015 The Authors The Plant Journal © 2015 John Wiley & Sons Ltd.

Evaluation of Inorganic/Organic Separators

NASA Technical Reports Server (NTRS)

Donnel, C. P., III

1976-01-01

Thirty-six (36) experimental 40AH sealed silver-zinc cells were constructed during phase I of this two (2) phase program. These cells were divided into six (6) groups of six (6) cells each. Each group of six (6) cells was evenly divided into two batches of three (3) cells each. Groups 1 through 4 each featured a different inorganic filler material in the slurry used to coat the separator substrate. Groups 5 and 6 featured an alternate method of separator bag construction. With the exception of the various separator materials, the parts and processes used to produce these thirty-six (36) cells were the same as those used to make the HR40-7 cell. The two (2) batches of cells in each cell group differed only in the lots of solutions and other separator slurry components used. Each cell was given two formation charge/discharge cycles prior to being shipped to NASA Lewis Research Center. Phase II of the program consisted of constructing another thirty-six (36) 40AH experimental cells in six (6) groups of six (6) cells each. Each group was distinguished by the type of precoated separator material used to fabricate separator bags. A new method of separator bag construction was used in this phase of the program. These cells were given two (2) formation cycles and shipped to NASA Lewis Research Center.

Raman spectrum reveals the cell cycle arrest of Triptolide-induced leukemic T-lymphocytes apoptosis

NASA Astrophysics Data System (ADS)

Zhang, Daosen; Feng, Yanyan; Zhang, Qinnan; Su, Xin; Lu, Xiaoxu; Liu, Shengde; Zhong, Liyun

2015-04-01

Triptolide (TPL), a traditional Chinese medicine extract, possesses anti-inflammatory and anti-tumor properties. Though some research results have implicated that Triptolide (TPL) can be utilized in the treatment of leukemia, it remains controversial about the mechanism of TPL-induced leukemic T-lymphocytes apoptosis. In this study, combining Raman spectroscopic data, principal component analysis (PCA) and atomic force microscopy (AFM) imaging, both the biochemical changes and morphological changes during TPL-induced cell apoptosis were presented. In contrast, the corresponding data during Daunorubicin (DNR)-induced cell apoptosis was also exhibited. The obtained results showed that Raman spectral changes during TPL-induced cell apoptosis were greatly different from DNR-induced cell apoptosis in the early stage of apoptosis but revealed the high similarity in the late stage of apoptosis. Moreover, above Raman spectral changes were respectively consistent with the morphological changes of different stages during TPL-induced apoptosis or DNR-induced apoptosis, including membrane shrinkage and blebbing, chromatin condensation and the formation of apoptotic bodies. Importantly, it was found that Raman spectral changes with TPL-induced apoptosis or DNR-induced apoptosis were respectively related with the cell cycle G1 phase arrest or G1 and S phase arrest.

Experimental study of a fuel cell power train for road transport application

NASA Astrophysics Data System (ADS)

Corbo, P.; Corcione, F. E.; Migliardini, F.; Veneri, O.

The development of fuel cell electric vehicles requires the on-board integration of fuel cell systems and electric energy storage devices, with an appropriate energy management system. The optimization of performance and efficiency needs an experimental analysis of the power train, which has to be effected in both stationary and transient conditions (including standard driving cycles). In this paper experimental results concerning the performance of a fuel cell power train are reported and discussed. In particular characterization results for a small sized fuel cell system (FCS), based on a 2.5 kW PEM stack, alone and coupled to an electric propulsion chain of 3.7 kW are presented and discussed. The control unit of the FCS allowed the main stack operative parameters (stoichiometric ratio, hydrogen and air pressure, temperature) to be varied and regulated in order to obtain optimized polarization and efficiency curves. Experimental runs effected on the power train during standard driving cycles have allowed the performance and efficiency of the individual components (fuel cell stack and auxiliaries, dc-dc converter, traction batteries, electric engine) to be evaluated, evidencing the role of output current and voltage of the dc-dc converter in directing the energy flows within the propulsion system.

Combination of HDAC inhibitor TSA and silibinin induces cell cycle arrest and apoptosis by targeting survivin and cyclinB1/Cdk1 in pancreatic cancer cells.

PubMed

Feng, Wan; Cai, Dawei; Zhang, Bin; Lou, Guochun; Zou, Xiaoping

2015-08-01

Histone deacetylases (HDAC) are involved in diverse biological processes and therefore emerge as potential targets for pancreatic cancer. Silibinin, an active component of silymarin, is known to inhibit growth of pancreatic cancer in vivo and in vitro. Herein, we examined the cytotoxic effects of TSA in combination with silibinin and investigated the possible mechanism in two pancreatic cancer cell lines (Panc1 and Capan2). Our study found that combination treatment of HDAC inhibitor and silibinin exerted additive growth inhibitory effect on pancreatic cancer cell. Annexin V-FITC/PI staining and flow cytometry analysis demonstrated that combination therapy induced G2/M cell cycle arrest and apoptosis in Panc1and Capan2 cells. The induction of apoptosis was further confirmed by evaluating the activation of caspases. Moreover, treatment with TSA and silibinin resulted in a profound reduction in the expression of cyclinA2, cyclinB1/Cdk1 and survivin. Taken together, our study might indicate that the novel combination of HDAC inhibitor and silibinin could offer therapeutic potential against pancreatic cancer. Copyright © 2015. Published by Elsevier Masson SAS.

p21, an important mediator of quiescence during pituitary tumor formation, is dispensable for normal pituitary development during embryogenesis.

PubMed Central

Monahan, Pamela; Himes, Ashley D.; Parfieniuk, Agata; Raetzman, Lori T.

2011-01-01

A delicate balance between proliferation and differentiation must be maintained in the developing pituitary to ensure the formation of the appropriate number of hormone producing cells. In the adult, proliferation is actively restrained to prevent tumor formation. The cyclin dependent kinase inhibitors (CDKIs) of the CIP/KIP family, p21, p27 and p57, mediate cell cycle inhibition. Although p21 is induced in the pituitary upon loss of Notch signaling or initiation of tumor formation to halt cell cycle progression, its role in normal pituitary organogenesis has not been explored. In wildtype pituitaries, expression of p21 is limited to a subset of cells embryonically as well as during the postnatal proliferative phase. Mice lacking p21 do not have altered cell proliferation during early embryogenesis, but do show a slight delay in separation of proliferating progenitors from the oral ectoderm. By embryonic day 16.5, p21 mutants have an alteration in the spatial distribution of proliferating pituitary progenitors, however there is no overall change in proliferation. At postnatal day 21, there appears to be no change in proliferation, as assessed by cells expressing Ki67 protein. However, p21 mutant pituitaries have significantly less mRNA of Myc and the cyclins Ccnb1, Ccnd1, Ccnd2 and Ccne1 than wildtype pituitaries. Interestingly, unlike the redundant role in cell cycle inhibition uncovered in p27/p57 double mutants, the pituitary of p21/p27 double mutants has a similar proliferation profile to p27 single mutants at the time points examined. Taken together, these studies demonstrate that unlike p27 or p57, p21 does not play a major role in control of progenitor proliferation in the developing pituitary. However, p21 may be required to maintain normal levels of cell cycle components. PMID:22154697

[The reentrant binomial model of nuclear anomalies growth in rhabdomyosarcoma RA-23 cell populations under increasing doze of rare ionizing radiation].

PubMed

Alekseeva, N P; Alekseev, A O; Vakhtin, Iu B; Kravtsov, V Iu; Kuzovatov, S N; Skorikova, T I

2008-01-01

Distributions of nuclear morphology anomalies in transplantable rabdomiosarcoma RA-23 cell populations were investigated under effect of ionizing radiation from 0 to 45 Gy. Internuclear bridges, nuclear protrusions and dumbbell-shaped nuclei were accepted for morphological anomalies. Empirical distributions of the number of anomalies per 100 nuclei were used. The adequate model of reentrant binomial distribution has been found. The sum of binomial random variables with binomial number of summands has such distribution. Averages of these random variables were named, accordingly, internal and external average reentrant components. Their maximum likelihood estimations were received. Statistical properties of these estimations were investigated by means of statistical modeling. It has been received that at equally significant correlation between the radiation dose and the average of nuclear anomalies in cell populations after two-three cellular cycles from the moment of irradiation in vivo the irradiation doze significantly correlates with internal average reentrant component, and in remote descendants of cell transplants irradiated in vitro - with external one.

Senescence-associated reprogramming promotes cancer stemness.

PubMed

Milanovic, Maja; Fan, Dorothy N Y; Belenki, Dimitri; Däbritz, J Henry M; Zhao, Zhen; Yu, Yong; Dörr, Jan R; Dimitrova, Lora; Lenze, Dido; Monteiro Barbosa, Ines A; Mendoza-Parra, Marco A; Kanashova, Tamara; Metzner, Marlen; Pardon, Katharina; Reimann, Maurice; Trumpp, Andreas; Dörken, Bernd; Zuber, Johannes; Gronemeyer, Hinrich; Hummel, Michael; Dittmar, Gunnar; Lee, Soyoung; Schmitt, Clemens A

2018-01-04

Cellular senescence is a stress-responsive cell-cycle arrest program that terminates the further expansion of (pre-)malignant cells. Key signalling components of the senescence machinery, such as p16 INK4a , p21 CIP1 and p53, as well as trimethylation of lysine 9 at histone H3 (H3K9me3), also operate as critical regulators of stem-cell functions (which are collectively termed 'stemness'). In cancer cells, a gain of stemness may have profound implications for tumour aggressiveness and clinical outcome. Here we investigated whether chemotherapy-induced senescence could change stem-cell-related properties of malignant cells. Gene expression and functional analyses comparing senescent and non-senescent B-cell lymphomas from Eμ-Myc transgenic mice revealed substantial upregulation of an adult tissue stem-cell signature, activated Wnt signalling, and distinct stem-cell markers in senescence. Using genetically switchable models of senescence targeting H3K9me3 or p53 to mimic spontaneous escape from the arrested condition, we found that cells released from senescence re-entered the cell cycle with strongly enhanced and Wnt-dependent clonogenic growth potential compared to virtually identical populations that had been equally exposed to chemotherapy but had never been senescent. In vivo, these previously senescent cells presented with a much higher tumour initiation potential. Notably, the temporary enforcement of senescence in p53-regulatable models of acute lymphoblastic leukaemia and acute myeloid leukaemia was found to reprogram non-stem bulk leukaemia cells into self-renewing, leukaemia-initiating stem cells. Our data, which are further supported by consistent results in human cancer cell lines and primary samples of human haematological malignancies, reveal that senescence-associated stemness is an unexpected, cell-autonomous feature that exerts its detrimental, highly aggressive growth potential upon escape from cell-cycle blockade, and is enriched in relapse tumours. These findings have profound implications for cancer therapy, and provide new mechanistic insights into the plasticity of cancer cells.

Characterization and functional analysis of a slow-cycling subpopulation in colorectal cancer enriched by cell cycle inducer combined chemotherapy.

PubMed

Wu, Feng-Hua; Mu, Lei; Li, Xiao-Lan; Hu, Yi-Bing; Liu, Hui; Han, Lin-Tao; Gong, Jian-Ping

2017-10-03

The concept of cancer stem cells has been proposed in various malignancies including colorectal cancer. Recent studies show direct evidence for quiescence slow-cycling cells playing a role in cancer stem cells. There exists an urgent need to isolate and better characterize these slow-cycling cells. In this study, we developed a new model to enrich slow-cycling tumor cells using cell-cycle inducer combined with cell cycle-dependent chemotherapy in vitro and in vivo . Our results show that Short-term exposure of colorectal cancer cells to chemotherapy combined with cell-cycle inducer enriches for a cell-cycle quiescent tumor cell population. Specifically, these slow-cycling tumor cells exhibit increased chemotherapy resistance in vitro and tumorigenicity in vivo . Notably, these cells are stem-cell like and participate in metastatic dormancy. Further exploration indicates that slow-cycling colorectal cancer cells in our model are less sensitive to cytokine-induced-killer cell mediated cytotoxic killing in vivo and in vitro . Collectively, our cell cycle inducer combined chemotherapy exposure model enriches for a slow-cycling, dormant, chemo-resistant tumor cell sub-population that are resistant to cytokine induced killer cell based immunotherapy. Studying unique signaling pathways in dormant tumor cells enriched by cell cycle inducer combined chemotherapy treatment is expected to identify novel therapeutic targets for preventing tumor recurrence.

Characterization and functional analysis of a slow-cycling subpopulation in colorectal cancer enriched by cell cycle inducer combined chemotherapy

PubMed Central

Wu, Feng-Hua; Mu, Lei; Li, Xiao-Lan; Hu, Yi-Bing; Liu, Hui; Han, Lin-Tao; Gong, Jian-Ping

2017-01-01

The concept of cancer stem cells has been proposed in various malignancies including colorectal cancer. Recent studies show direct evidence for quiescence slow-cycling cells playing a role in cancer stem cells. There exists an urgent need to isolate and better characterize these slow-cycling cells. In this study, we developed a new model to enrich slow-cycling tumor cells using cell-cycle inducer combined with cell cycle-dependent chemotherapy in vitro and in vivo. Our results show that Short-term exposure of colorectal cancer cells to chemotherapy combined with cell-cycle inducer enriches for a cell-cycle quiescent tumor cell population. Specifically, these slow-cycling tumor cells exhibit increased chemotherapy resistance in vitro and tumorigenicity in vivo. Notably, these cells are stem-cell like and participate in metastatic dormancy. Further exploration indicates that slow-cycling colorectal cancer cells in our model are less sensitive to cytokine-induced-killer cell mediated cytotoxic killing in vivo and in vitro. Collectively, our cell cycle inducer combined chemotherapy exposure model enriches for a slow-cycling, dormant, chemo-resistant tumor cell sub-population that are resistant to cytokine induced killer cell based immunotherapy. Studying unique signaling pathways in dormant tumor cells enriched by cell cycle inducer combined chemotherapy treatment is expected to identify novel therapeutic targets for preventing tumor recurrence. PMID:29108242

Key optical components for spaceborne lasers

NASA Astrophysics Data System (ADS)

Löhring, J.; Winzen, M.; Faidel, H.; Miesner, J.; Plum, D.; Klein, J.; Fitzau, O.; Giesberts, M.; Brandenburg, W.; Seidel, A.; Schwanen, N.; Riesters, D.; Hengesbach, S.; Hoffmann, H.-D.

2016-03-01

Spaceborne lidar (light detection and ranging) systems have a large potential to become powerful instruments in the field of atmospheric research. Obviously, they have to be in operation for about three years without any maintenance like readjusting. Furthermore, they have to withstand strong temperature cycles typically in the range of -30 to +50 °C as well as mechanical shocks and vibrations, especially during launch. Additionally, the avoidance of any organic material inside the laser box is required, particularly in UV lasers. For atmospheric research pulses of about several 10 mJ at repetition rates of several 10 Hz are required in many cases. Those parameters are typically addressed by DPSSL that comprise components like: laser crystals, nonlinear crystals in pockels cells, faraday isolators and frequency converters, passive fibers, diode lasers and of course a lot of mirrors and lenses. In particular, some components have strong requirements regarding their tilt stability that is often in the 10 μrad range. In most of the cases components and packages that are used for industrial lasers do not fulfil all those requirements. Thus, the packaging of all these key components has been developed to meet those specifications only making use of metal and ceramics beside the optical component itself. All joints between the optical component and the laser baseplate are soldered or screwed. No clamps or adhesives are used. Most of the critical properties like tilting after temperature cycling have been proven in several tests. Currently, these components are used to build up first prototypes for spaceborne systems.

Compositional and expression analyses of the glideosome during the Plasmodium life cycle reveal an additional myosin light chain required for maximum motility

PubMed Central

Green, Judith L.; Wall, Richard J.; Vahokoski, Juha; Yusuf, Noor A.; Ridzuan, Mohd A. Mohd; Stanway, Rebecca R.; Stock, Jessica; Knuepfer, Ellen; Brady, Declan; Martin, Stephen R.; Howell, Steven A.; Pires, Isa P.; Moon, Robert W.; Molloy, Justin E.; Kursula, Inari; Tewari, Rita

2017-01-01

Myosin A (MyoA) is a Class XIV myosin implicated in gliding motility and host cell and tissue invasion by malaria parasites. MyoA is part of a membrane-associated protein complex called the glideosome, which is essential for parasite motility and includes the MyoA light chain myosin tail domain–interacting protein (MTIP) and several glideosome-associated proteins (GAPs). However, most studies of MyoA have focused on single stages of the parasite life cycle. We examined MyoA expression throughout the Plasmodium berghei life cycle in both mammalian and insect hosts. In extracellular ookinetes, sporozoites, and merozoites, MyoA was located at the parasite periphery. In the sexual stages, zygote formation and initial ookinete differentiation precede MyoA synthesis and deposition, which occurred only in the developing protuberance. In developing intracellular asexual blood stages, MyoA was synthesized in mature schizonts and was located at the periphery of segmenting merozoites, where it remained throughout maturation, merozoite egress, and host cell invasion. Besides the known GAPs in the malaria parasite, the complex included GAP40, an additional myosin light chain designated essential light chain (ELC), and several other candidate components. This ELC bound the MyoA neck region adjacent to the MTIP-binding site, and both myosin light chains co-located to the glideosome. Co-expression of MyoA with its two light chains revealed that the presence of both light chains enhances MyoA-dependent actin motility. In conclusion, we have established a system to study the interplay and function of the three glideosome components, enabling the assessment of inhibitors that target this motor complex to block host cell invasion. PMID:28893907

Compositional and expression analyses of the glideosome during the Plasmodium life cycle reveal an additional myosin light chain required for maximum motility.

PubMed

Green, Judith L; Wall, Richard J; Vahokoski, Juha; Yusuf, Noor A; Ridzuan, Mohd A Mohd; Stanway, Rebecca R; Stock, Jessica; Knuepfer, Ellen; Brady, Declan; Martin, Stephen R; Howell, Steven A; Pires, Isa P; Moon, Robert W; Molloy, Justin E; Kursula, Inari; Tewari, Rita; Holder, Anthony A

2017-10-27

Myosin A (MyoA) is a Class XIV myosin implicated in gliding motility and host cell and tissue invasion by malaria parasites. MyoA is part of a membrane-associated protein complex called the glideosome, which is essential for parasite motility and includes the MyoA light chain myosin tail domain-interacting protein (MTIP) and several glideosome-associated proteins (GAPs). However, most studies of MyoA have focused on single stages of the parasite life cycle. We examined MyoA expression throughout the Plasmodium berghei life cycle in both mammalian and insect hosts. In extracellular ookinetes, sporozoites, and merozoites, MyoA was located at the parasite periphery. In the sexual stages, zygote formation and initial ookinete differentiation precede MyoA synthesis and deposition, which occurred only in the developing protuberance. In developing intracellular asexual blood stages, MyoA was synthesized in mature schizonts and was located at the periphery of segmenting merozoites, where it remained throughout maturation, merozoite egress, and host cell invasion. Besides the known GAPs in the malaria parasite, the complex included GAP40, an additional myosin light chain designated essential light chain (ELC), and several other candidate components. This ELC bound the MyoA neck region adjacent to the MTIP-binding site, and both myosin light chains co-located to the glideosome. Co-expression of MyoA with its two light chains revealed that the presence of both light chains enhances MyoA-dependent actin motility. In conclusion, we have established a system to study the interplay and function of the three glideosome components, enabling the assessment of inhibitors that target this motor complex to block host cell invasion. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Chromosome damage evolution after low and high LET irradiation

NASA Astrophysics Data System (ADS)

Andreev, Sergey; Eidelman, Yuri

Ionizing radiation induces DNA and chromatin lesions which are converted to chromosome lesions detected in the first post-irradiation mitosis by classic cytogenetic techniques as chromosomal aberrations (CAs). These techniques allow to monitor also delayed aberrations observed after many cell generations post-irradiation - the manifestation of chromosomal instability phenotype (CIN). The problem discussed is how to predict time evolution from initial to delayed DNA/chromosome damage. To address this question, in the present work a mechanistic model of CIN is elaborated which integrates pathways of (*) DNA damage induction and its conversion to chromosome lesions (aberrations), (**) lesion transmission and generation through cell cycles. Delayed aberrations in subsequent cycles are formed in the model owing to two pathways, DNA damage generation de novo as well as CA transmission from previous cycles. DNA damage generation rate is assumed to consist of bystander and non-bystander components. Bystander signals impact all cells roughly equally, whereas non-bystander DSB generation rate differs for the descendants of unirradiated and irradiated cells. Monte Carlo simulation of processes underlying CIN allows to predict the time evolution of initial radiation-induced damage - kinetics curve for delayed unstable aberrations (dicentrics) together with dose response and RBE as a function of time after high vs low LET irradiation. The experimental data for radiation-induced CIN in TK6 lymphoblastoid cells and human lymphocytes irradiated with low (gamma) and high (Fe, C) LET radiation are analyzed on the basis of the proposed model. One of the conclusions is that without bystander signaling, just taking into account the initial DNA damage and non-bystander DSB generation, it is impossible to describe the available experimental data for high-LET-induced CIN. The exact contribution of bystander effects for high vs low LET remains unknown, but the relative contribution may be assessed at large times after initial acute irradiation. RBE for delayed aberrations depends on LET, time and cell line, which probably reflects a genetic background for bystander component. The proposed modeling approach creates a basis for integration of complex network of bystander/inflammatory signaling in systems-level platform for quantification of radiation induced CIN.

Studies on the Biotribological and Biological Behavior of Thermally Oxidized Ti6Al4V for Use in Artificial Cervical Disk

NASA Astrophysics Data System (ADS)

Wang, Song; Li, Junhui; Lu, Junzhe; Tyagi, Rajnesh; Liao, Zhenhua; Feng, Pingfa; Liu, Weiqiang

2017-05-01

The artificial cervical disk was simplified and considered as a ball-on-socket model with the material configuration of ultra-high molecular weight polyethylene and Ti6Al4V (PE-on-TC4). In order to improve the wear resistance, an optimized thermal oxidation (TO) coating was applied on TC4 component. The long-term wear behavior of the model was assessed in vitro using a wear simulator under 10 million cycles (MC) testing intervals. The biological behavior was investigated by bone marrow-derived mesenchymal stem cells (BMSCs) cell attachment and cell viability/proliferation assays, respectively. The total average wear rate for PE/TC4 pair was found to be 0.81 mg/MC, whereas the same was about 0.96 mg/MC for PE/TO pair. The wear rate of the metal has been neglected in comparison with that of the mating polymer. PE component was found to suffer severe damage characterized by scratches, fatigue cracks and arc-shaped wear grooves on the edge zone of ball. The dominant wear mechanism was abrasion for metal component while the dominant failure mechanism was a mix of plowing, fatigue and plastic deformation for polymer component. TO coating improved the cell attachment property of TC4, and the cell viability results were also quite good. TO coating protected TC4 from being plowed and avoided the release of toxic metal ions. However, this intensified the wear of PE component. Considering the biotribological and biological behavior in totality, TO coating could still be promising when applied in articulation surfaces.

Differential Influence of Components Resulting from Atmospheric-Pressure Plasma on Integrin Expression of Human HaCaT Keratinocytes

PubMed Central

Haertel, Beate; Straßenburg, Susanne; Wende, Kristian; von Woedtke, Thomas

2013-01-01

Adequate chronic wound healing is a major problem in medicine. A new solution might be non-thermal atmospheric-pressure plasma effectively inactivating microorganisms and influencing cells in wound healing. Plasma components as, for example, radicals can affect cells differently. HaCaT keratinocytes were treated with Dielectric Barrier Discharge plasma (DBD/air, DBD/argon), ozone or hydrogen peroxide to find the components responsible for changes in integrin expression, intracellular ROS formation or apoptosis induction. Dependent on plasma treatment time reduction of recovered cells was observed with no increase of apoptotic cells, but breakdown of mitochondrial membrane potential. DBD/air plasma increased integrins and intracellular ROS. DBD/argon caused minor changes. About 100 ppm ozone did not influence integrins. Hydrogen peroxide caused similar effects compared to DBD/air plasma. In conclusion, effects depended on working gas and exposure time to plasma. Short treatment cycles did neither change integrins nor induce apoptosis or ROS. Longer treatments changed integrins as important for influencing wound healing. Plasma effects on integrins are rather attributed to induction of other ROS than to generation of ozone. Changes of integrins by plasma may provide new solutions of improving wound healing, however, conditions are needed which allow initiating the relevant influence on integrins without being cytotoxic to cells. PMID:23936843

Annatto Tocotrienol Induces a Cytotoxic Effect on Human Prostate Cancer PC3 Cells via the Simultaneous Inhibition of Src and Stat3.

PubMed

Sugahara, Ryosuke; Sato, Ayami; Uchida, Asuka; Shiozawa, Shinya; Sato, Chiaki; Virgona, Nantiga; Yano, Tomohiro

2015-01-01

Prostate cancer is one of the most frequently occurring cancers and often acquires the potential of androgen-independent growth as a malignant phenotype. Androgen-independent prostate cancer has severe chemoresistance towards conventional chemotherapeutic agents, so a new treatment approach is required for curing such prostate cancer. In this context, the present study was undertaken to check if annatto tocotrienol (main component δ-tocotrienol) could suppress cell growth in human prostate cancer (PC3, androgen-independent type) cells via the inhibition of Src and Stat3. The tocotrienol showed cytotoxic effects on PC3 cells in a dose-dependent manner, and the effect depended on G1 arrest in the cell cycle and subsequent induction of apoptosis. In a cytotoxic dose, the tocotrienol suppressed cellular growth via the simultaneous inhibition of Src and Stat3. Similarly, the treatment combination of both Src and Stat3 inhibitors induced cytotoxic effects in PC3 cells in an additive manner compared to each by itself. With respect to cell cycle regulation and the induction of apoptosis, the combination treatment showed a similar effect to that of the tocotrienol treatment. These results suggest that annatto tocotrienol effectively induces cytotoxicity in androgen-independent prostate cancer cells via the suppression of Src and Stat3.

cis Retinol oxidation regulates photoreceptor access to the retina visual cycle and cone pigment regeneration

PubMed Central

Sato, Shinya

2016-01-01

Key points This study explores the nature of the cis retinol that Müller cells in the retina provide to cones for the regeneration of their visual pigment.We report that the retina visual cycle provides cones exclusively with 11‐cis chromophore in both salamander and mouse and show that this selectivity is dependent on the 11‐cis‐specific cellular retinaldehyde binding protein (CRALBP) present in Müller cells.Even though salamander blue cones and green rods share the same visual pigment, only blue cones but not green rods are able to dark‐adapt in the retina following a bleach and to use exogenous 9‐cis retinol for pigment regeneration, suggesting that access to the retina visual cycle is cone‐specific and pigment‐independent.Our results show that the retina produces 11‐cis retinol that can be oxidized and used for pigment regeneration and dark adaptation selectively in cones and not in rods. Abstract Chromophore supply by the retinal Müller cells (retina visual cycle) supports the efficient pigment regeneration required for cone photoreceptor function in bright light. Surprisingly, a large fraction of the chromophore produced by dihydroceramide desaturase‐1, the putative all‐trans retinol isomerase in Müller cells, appears to be 9‐cis retinol. In contrast, the canonical retinal pigment epithelium (RPE) visual cycle produces exclusively 11‐cis retinal. Here, we used the different absorption spectra of 9‐cis and 11‐cis pigments to identify the isoform of the chromophore produced by the visual cycle of the intact retina. We found that the spectral sensitivity of salamander and mouse cones dark‐adapted in the isolated retina (with only the retina visual cycle) was similar to that of cones dark‐adapted in the intact eye (with both the RPE and retina visual cycles) and consistent with pure 11‐cis pigment composition. However, in mice lacking the cellular retinaldehyde binding protein (CRALBP), cone spectral sensitivity contained a substantial 9‐cis component. Thus, the retina visual cycle provides cones exclusively with 11‐cis chromophore and this process is mediated by the 11‐cis selective CRALBP in Müller cells. Finally, despite sharing the same pigment, salamander blue cones, but not green rods, recovered their sensitivity in the isolated retina. Exogenous 9‐cis retinol produced robust sensitivity recovery in bleached red and blue cones but not in red and green rods, suggesting that cis retinol oxidation restricts access to the retina visual cycle to cones. PMID:27385534

Design and fabrication of silver-hydrogen cells

NASA Technical Reports Server (NTRS)

Klein, M. G.

1975-01-01

The design and fabrication of silver-hydrogen secondary cells capable of delivering higher energy densities than comparable nickel-cadmium and nickel-hydrogen cells and relatively high cycle life is presented. An experimental task utilizing single electrode pairs for the optimization of the individual electrode components, the preparation of a design for lightweight 20Ahr cells, and the fabrication of four 20Ahr cells in heavy wall test housing containing electrode stacks of the lightweight design are described. The design approach is based on the use of a single cylindrical self-contained cell with a stacked disc sequence of electrodes. The electrode stack design is based on the use of NASA- Astropower Separator Material, PPF fuel cell anodes, an intercell electrolyte reservoir concept and sintered silver electrodes. Results of performance tests are given.

Duration of division-related events in cleaving sand dollar eggs.

PubMed

Rappaport, R; Rappaport, B N

1993-07-01

A minimal mechanism for cytokinesis comprises a stimulus-to-surface contraction, a receptive surface, and a localized surface contractile mechanism. Duration of each is brief and times when they function are predictable. The processes that begin and end the functional period of each component were investigated. Sand dollar blastomeres from the completion of first cleavage to the beginning of fourth cleavage were used. By changing a cell's shape, it was possible to determine whether its capacity to accomplish an activity is restricted to its usual time frame. The first appearance of the furrow was advanced about 5 min by confining the mitotic apparatus in a narrow cytoplasmic cylinder. The period when the mitotic apparatus induces furrowing was prolonged about 18 min by moving the mitotic apparatus in an elongate cell each time the furrow appeared. The period of active furrowing was prolonged to about 21.8 min by pushing the mitotic apparatus close to the cell margin and then stretching the region through which the unilateral furrow must pass. In relation to normal division cycle events, results showed that each event of cytokinesis can operate both before and after its normal active period. Components of the mechanism are capable of functioning for about half the period of the division cycle. Normal timing of events may be determined by geometrical factors and the normal consequences of each activity.

Epidermal Growth Factor Receptor activation promotes ADA3 acetylation through the AKT-p300 pathway

PubMed Central

Srivastava, Shashank; Mohibi, Shakur; Mirza, Sameer; Band, Hamid; Band, Vimla

2017-01-01

ABSTRACT The ADA3 (Alteration/Deficiency in Activation 3) protein is an essential adaptor component of several Lysine Acetyltransferase (KAT) complexes involved in chromatin modifications. Previously, we and others have demonstrated a crucial role of ADA3 in cell cycle progression and in maintenance of genomic stability. Recently, we have shown that acetylation of ADA3 is key to its role in cell cycle progression. Here, we demonstrate that AKT activation downstream of Epidermal Growth Factor Receptor (EGFR) family proteins stimulation leads to phosphorylation of p300, which in turn promotes the acetylation of ADA3. Inhibition of upstream receptor tyrosine kinases (RTKs), HER1 (EGFR)/HER2 by lapatinib and the accompanying reduction of phospho-AKT levels led to a decrease in p300 phosphorylation and ADA3 protein levels. The p300/PCAF inhibitor garcinol also destabilized the ADA3 protein in a proteasome-dependent manner and an ADA3 mutant with K→R mutations exhibited a marked increase in half-life, consistent with opposite role of acetylation and ubiquitination of ADA3 on shared lysine residues. ADA3 knockdown led to cell cycle inhibitory effects, as well as apoptosis similar to those induced by lapatinib treatment of HER2+ breast cancer cells, as seen by accumulation of CDK inhibitor p27, reduction in mitotic marker pH3(S10), and a decrease in the S-phase marker PCNA, as well as the appearance of cleaved PARP. Taken together our results reveal a novel RTK-AKT-p300-ADA3 signaling pathway involved in growth factor-induced cell cycle progression. PMID:28759294

Dietary Bioactive Diallyl Trisulfide in Cancer Prevention and Treatment.

PubMed

Puccinelli, Michael T; Stan, Silvia D

2017-07-28

Bioactive dietary agents have been shown to regulate multiple cancer hallmark pathways. Epidemiologic studies have linked consumption of Allium vegetables, such as garlic and onions, to decreased incidence of cancer. Diallyl trisulfide (DATS), a bioactive compound derived from Allium vegetables, has been investigated as an anti-cancer and chemopreventive agent. Preclinical studies provide ample evidence that DATS regulates multiple cancer hallmark pathways including cell cycle, apoptosis, angiogenesis, invasion, and metastasis. DATS has been shown to arrest cancer cells at multiple stages of the cell cycle with the G2/M arrest being the most widely reported. Additionally, increased pro-apoptotic capacity as a result of regulating intrinsic and extrinsic apoptotic pathway components has been widely reported following DATS treatment. Invasion, migration, and angiogenesis represent emerging targets of DATS and support its anti-cancer properties. This review summarizes DATS mechanisms of action as an anti-cancer and chemopreventive agent. These studies provide rationale for future investigation into its use as a cancer chemopreventive agent.

Defining Hsp70 Subnetworks in Dengue Virus Replication Reveals Key Vulnerability in Flavivirus Infection

PubMed Central

Taguwa, Shuhei; Maringer, Kevin; Li, Xiaokai; Bernal-Rubio, Dabeiba; Rauch, Jennifer N.; Gestwicki, Jason E.; Andino, Raul; Fernandez-Sesma, Ana; Frydman, Judith

2015-01-01

Summary Viral protein homeostasis depends entirely on the machinery of the infected cell. Accordingly, viruses can illuminate the interplay between cellular proteostasis components and their distinct substrates. Here we define how the Hsp70 chaperone network mediates the dengue virus life cycle. Cytosolic Hsp70 isoforms are required at distinct steps of the viral cycle, including entry, RNA replication and virion biogenesis. Hsp70 function at each step is specified by nine distinct DNAJ cofactors. Of these, DnaJB11 relocalizes to virus-induced replication complexes to promote RNA synthesis, while DnaJB6 associates with capsid protein and facilitates virion biogenesis. Importantly, an allosteric Hsp70 inhibitor, JG40, potently blocks infection of different dengue serotypes in human primary blood cells without eliciting viral resistance or exerting toxicity to the host cells. JG40 also blocks replication of other medically-important flaviviruses including yellow fever, West Nile and Japanese encephalitis viruses. Thus, targeting host Hsp70 subnetworks provides a path for broad-spectrum antivirals. PMID:26582131

Dietary Bioactive Diallyl Trisulfide in Cancer Prevention and Treatment

PubMed Central

Puccinelli, Michael T.; Stan, Silvia D.

2017-01-01

Bioactive dietary agents have been shown to regulate multiple cancer hallmark pathways. Epidemiologic studies have linked consumption of Allium vegetables, such as garlic and onions, to decreased incidence of cancer. Diallyl trisulfide (DATS), a bioactive compound derived from Allium vegetables, has been investigated as an anti-cancer and chemopreventive agent. Preclinical studies provide ample evidence that DATS regulates multiple cancer hallmark pathways including cell cycle, apoptosis, angiogenesis, invasion, and metastasis. DATS has been shown to arrest cancer cells at multiple stages of the cell cycle with the G2/M arrest being the most widely reported. Additionally, increased pro-apoptotic capacity as a result of regulating intrinsic and extrinsic apoptotic pathway components has been widely reported following DATS treatment. Invasion, migration, and angiogenesis represent emerging targets of DATS and support its anti-cancer properties. This review summarizes DATS mechanisms of action as an anti-cancer and chemopreventive agent. These studies provide rationale for future investigation into its use as a cancer chemopreventive agent. PMID:28788092

Nitrogen-doped three-dimensional graphene-supported platinum catalysts for polymer electrolyte membrane fuel cells application

NASA Astrophysics Data System (ADS)

Chu, Fuqiang; Li, Xingxing; Yuan, Wensen; Zhu, Huanhuan; Qin, Yong; Zhang, Shuai; Yuan, Ningyi; Lin, Bencai; Ding, Jianning

Catalysts are a key component of polymer electrolyte membrane fuel cells (PEMFCs). In this work, nitrogen-doped three-dimensional graphene-supported platinum (Pt-3DNG) catalysts are successfully prepared and characterized. SEM and TEM images show the Pt nanoparticles are uniformly dispersed in the sheets of nitrogen-doped 3DNG. Compared with that of the commercial Pt/C catalysts, Pt-3DNG show much better oxygen reduction reaction (ORR) activity and cycling stability, and the reduction in limit current density after 1000 cycles is only about 1.6% for the Pt-3DNG catalysts, whereas 7.2% for the commercial Pt/C catalysts. The single cell using Pt-3DNG catalysts in both the anode and the cathode show a higher peak power density (21.47mW cm-2) than that using commercial Pt/C catalysts (20.17mW cm-2) under the same conditions. These properties make this type of catalyst suitable for the application in PEMFCs.

Update on International Space Station Nickel-Hydrogen Battery On-Orbit Performance

NASA Technical Reports Server (NTRS)

Dalton, Penni; Cohen, Fred

2003-01-01

International Space Station (ISS) Electric Power System (EPS) utilizes Nickel-Hydrogen (Ni-H2) batteries as part of its power system to store electrical energy. The batteries are charged during insolation and discharged during eclipse. The batteries are designed to operate at a 35% depth of discharge (DOD) maximum during normal operation. Thirty-eight individual pressure vessel (IPV) Ni-H2 battery cells are series-connected and packaged in an Orbital Replacement Unit (ORU). Two ORUs are series-connected utilizing a total of 76 cells, to form one battery. The ISS is the first application for low earth orbit (LEO) cycling of this quantity of series-connected cells. The P6 (Port) Integrated Equipment Assembly (IEA) containing the initial ISS high-power components was successfully launched on November 30, 2000. The IEA contains 12 Battery Subassembly ORUs (6 batteries) that provide station power during eclipse periods. This paper will discuss the battery performance data after two and a half years of cycling.

International Space Station Nickel-Hydrogen Battery On-Orbit Performance

NASA Technical Reports Server (NTRS)

Dalton, Penni; Cohen, Fred

2002-01-01

International Space Station (ISS) Electric Power System (EPS) utilizes Nickel-Hydrogen (Ni-H2) batteries as part of its power system to store electrical energy. The batteries are charged during insolation and discharged during eclipse. The batteries are designed to operate at a 35 percent depth of discharge (DOD) maximum during normal operation. Thirty-eight individual pressure vessel (IPV) Ni-H2 battery cells are series-connected and packaged in an Orbital Replacement Unit (ORU). Two ORUs are series-connected utilizing a total of 76 cells to form one battery. The ISS is the first application for low earth orbit (LEO) cycling of this quantity of series-connected cells. The P6 (Port) Integrated Equipment Assembly (IEA) containing the initial ISS high-power components was successfully launched on November 30, 2000. The IEA contains 12 Battery Subassembly ORUs (6 batteries) that provide station power during eclipse periods. This paper will discuss the battery performance data after eighteen months of cycling.

Solid oxide fuel cell hybrid system: Control strategy for stand-alone configurations

NASA Astrophysics Data System (ADS)

Ferrari, Mario L.

2011-03-01

The aim of this study is the development and testing of a control system for solid oxide fuel cell hybrid systems through dynamic simulations. Due to the complexity of these cycles, several parameters, such as the turbine rotational speed, the temperatures within the fuel cell, the differential pressure between the anodic and the cathodic side and the Steam-To-Carbon Ratio need to be monitored and kept within safe limits. Furthermore, in stand-alone conditions the system response to load variations is required to meet the global plant power demand at any time, supporting global load variations and avoiding dangerous or unstable conditions. The plant component models and their integration were carried out in previous studies. This paper focuses on the control strategy required for managing the net electrical power from the system, avoiding malfunctions or damage. Once the control system was developed and tuned, its performance was evaluated by simulating the transient behaviour of the whole hybrid cycle: the results for several operating conditions are presented and discussed.

Mitochondrial shaping cuts.

PubMed

Escobar-Henriques, Mafalda; Langer, Thomas

2006-01-01

A broad range of cellular processes are regulated by proteolytic events. Proteolysis has now also been established to control mitochondrial morphology which results from the balanced action of fusion and fission. Two out of three known core components of the mitochondrial fusion machinery are under proteolytic control. The GTPase Fzo1 in the outer membrane of mitochondria is degraded along two independent proteolytic pathways. One controls mitochondrial fusion in vegetatively growing cells, the other one acts upon mating factor-induced cell cycle arrest. Fusion also depends on proteolytic processing of the GTPase Mgm1 by the rhomboid protease Pcp1 in the inner membrane of mitochondria. Functional links of AAA proteases or other proteolytic components to mitochondrial dynamics are just emerging. This review summarises the current understanding of regulatory roles of proteolytic processes for mitochondrial plasticity.

Fumarate hydratase is a critical metabolic regulator of hematopoietic stem cell functions.

PubMed

Guitart, Amelie V; Panagopoulou, Theano I; Villacreces, Arnaud; Vukovic, Milica; Sepulveda, Catarina; Allen, Lewis; Carter, Roderick N; van de Lagemaat, Louie N; Morgan, Marcos; Giles, Peter; Sas, Zuzanna; Gonzalez, Marta Vila; Lawson, Hannah; Paris, Jasmin; Edwards-Hicks, Joy; Schaak, Katrin; Subramani, Chithra; Gezer, Deniz; Armesilla-Diaz, Alejandro; Wills, Jimi; Easterbrook, Aaron; Coman, David; So, Chi Wai Eric; O'Carroll, Donal; Vernimmen, Douglas; Rodrigues, Neil P; Pollard, Patrick J; Morton, Nicholas M; Finch, Andrew; Kranc, Kamil R

2017-03-06

Strict regulation of stem cell metabolism is essential for tissue functions and tumor suppression. In this study, we investigated the role of fumarate hydratase (Fh1), a key component of the mitochondrial tricarboxylic acid (TCA) cycle and cytosolic fumarate metabolism, in normal and leukemic hematopoiesis. Hematopoiesis-specific Fh1 deletion (resulting in endogenous fumarate accumulation and a genetic TCA cycle block reflected by decreased maximal mitochondrial respiration) caused lethal fetal liver hematopoietic defects and hematopoietic stem cell (HSC) failure. Reexpression of extramitochondrial Fh1 (which normalized fumarate levels but not maximal mitochondrial respiration) rescued these phenotypes, indicating the causal role of cellular fumarate accumulation. However, HSCs lacking mitochondrial Fh1 (which had normal fumarate levels but defective maximal mitochondrial respiration) failed to self-renew and displayed lymphoid differentiation defects. In contrast, leukemia-initiating cells lacking mitochondrial Fh1 efficiently propagated Meis1 / Hoxa9 -driven leukemia. Thus, we identify novel roles for fumarate metabolism in HSC maintenance and hematopoietic differentiation and reveal a differential requirement for mitochondrial Fh1 in normal hematopoiesis and leukemia propagation. © 2017 Guitart et al.

Gigantism in a bacterium, Epulopiscium fishelsoni, correlates with complex patterns in arrangement, quantity, and segregation of DNA.

PubMed

Bresler, V; Montgomery, W L; Fishelson, L; Pollak, P E

1998-11-01

Epulopiscium fishelsoni, gut symbiont of the brown surgeonfish (Acanthurus nigrofuscus) in the Red Sea, attains a larger size than any other eubacterium, varies 10- to 20-fold in length (and >2, 000-fold in volume), and undergoes a complex daily life cycle. In early morning, nucleoids contain highly condensed DNA in elongate, chromosome-like structures which are physically separated from the general cytoplasm. Cell division involves production of two (rarely three) nucleoids within a cell, deposition of cell walls around expanded nucleoids, and emergence of daughter cells from the parent cell. Fluorescence measurements of DNA, RNA, and other cell components indicate the following. DNA quantity is proportional to cell volume over cell lengths of approximately 30 micrometers to >500 micrometers. For cells of a given size, nucleoids of cells with two nucleoids (binucleoid) contain approximately equal amounts of DNA. And each nucleoid of a binucleoid cell contains one-half the DNA of the single nucleoid in a uninucleoid cell of the same size. The life cycle involves approximately equal subdivision of DNA among daughter cells, formation of apical caps of condensed DNA from previously decondensed and diffusely distributed DNA, and "pinching" of DNA near the middle of the cell in the absence of new wall formation. Mechanisms underlying these patterns remain unclear, but formation of daughter nucleoids and cells occurs both during diurnal periods of host feeding and bacterial cell growth and during nocturnal periods of host inactivity when mean bacterial cell size declines.

The Physarum polycephalum Genome Reveals Extensive Use of Prokaryotic Two-Component and Metazoan-Type Tyrosine Kinase Signaling

PubMed Central

Schaap, Pauline; Barrantes, Israel; Minx, Pat; Sasaki, Narie; Anderson, Roger W.; Bénard, Marianne; Biggar, Kyle K.; Buchler, Nicolas E.; Bundschuh, Ralf; Chen, Xiao; Fronick, Catrina; Fulton, Lucinda; Golderer, Georg; Jahn, Niels; Knoop, Volker; Landweber, Laura F.; Maric, Chrystelle; Miller, Dennis; Noegel, Angelika A.; Peace, Rob; Pierron, Gérard; Sasaki, Taeko; Schallenberg-Rüdinger, Mareike; Schleicher, Michael; Singh, Reema; Spaller, Thomas; Storey, Kenneth B.; Suzuki, Takamasa; Tomlinson, Chad; Tyson, John J.; Warren, Wesley C.; Werner, Ernst R.; Werner-Felmayer, Gabriele; Wilson, Richard K.; Winckler, Thomas; Gott, Jonatha M.; Glöckner, Gernot; Marwan, Wolfgang

2016-01-01

Physarum polycephalum is a well-studied microbial eukaryote with unique experimental attributes relative to other experimental model organisms. It has a sophisticated life cycle with several distinct stages including amoebal, flagellated, and plasmodial cells. It is unusual in switching between open and closed mitosis according to specific life-cycle stages. Here we present the analysis of the genome of this enigmatic and important model organism and compare it with closely related species. The genome is littered with simple and complex repeats and the coding regions are frequently interrupted by introns with a mean size of 100 bases. Complemented with extensive transcriptome data, we define approximately 31,000 gene loci, providing unexpected insights into early eukaryote evolution. We describe extensive use of histidine kinase-based two-component systems and tyrosine kinase signaling, the presence of bacterial and plant type photoreceptors (phytochromes, cryptochrome, and phototropin) and of plant-type pentatricopeptide repeat proteins, as well as metabolic pathways, and a cell cycle control system typically found in more complex eukaryotes. Our analysis characterizes P. polycephalum as a prototypical eukaryote with features attributed to the last common ancestor of Amorphea, that is, the Amoebozoa and Opisthokonts. Specifically, the presence of tyrosine kinases in Acanthamoeba and Physarum as representatives of two distantly related subdivisions of Amoebozoa argues against the later emergence of tyrosine kinase signaling in the opisthokont lineage and also against the acquisition by horizontal gene transfer. PMID:26615215

The circadian coordination of cell biology.

PubMed

Chaix, Amandine; Zarrinpar, Amir; Panda, Satchidananda

2016-10-10

Circadian clocks are cell-autonomous timing mechanisms that organize cell functions in a 24-h periodicity. In mammals, the main circadian oscillator consists of transcription-translation feedback loops composed of transcriptional regulators, enzymes, and scaffolds that generate and sustain daily oscillations of their own transcript and protein levels. The clock components and their targets impart rhythmic functions to many gene products through transcriptional, posttranscriptional, translational, and posttranslational mechanisms. This, in turn, temporally coordinates many signaling pathways, metabolic activity, organelles' structure and functions, as well as the cell cycle and the tissue-specific functions of differentiated cells. When the functions of these circadian oscillators are disrupted by age, environment, or genetic mutation, the temporal coordination of cellular functions is lost, reducing organismal health and fitness. © 2016 Chaix et al.

Secondary lithium batteries for space applications

NASA Technical Reports Server (NTRS)

Carter, B.; Khanna, S. K.; Yen, S. P. S.; Shen, D.; Somoano, R. B.

1981-01-01

Secondary lithium cells which use a LiAsF6-2-Me-THF electrolyte and a TiS2 intercalatable cathode exhibit encouraging cycle life at ambient temperature. Electrochemical and surface analytical studies indicate that the electrolyte is unstable in the presence of metallic lithium, leading to the formation of a lithium passivating film composed of lithium arsenic oxyfluorides and lithium fluorsilicates. The lithium cyclability remains as the most important problem to solve. Different electrolyte solvents, such as sulfolane, exhibit promising characteristics but lead to new compatibility problems with the other cell component materials.

Performance Characteristics of Lithium-Ion Prototype Batteries for Mars Surveyor Program 2001 Lander

NASA Technical Reports Server (NTRS)

Smart, M. C.; Ratnakumar, B. V.; Whitcanack, L.; Surampudi, S.; Byers, J.; Marsh, R. A.

2000-01-01

A viewgraph presentation outlines the scientific payload, expected launch date and tasks, and an image of the Mars Surveyor 2001 Lander components. The Lander's battery specifications are given. The program objectives for the Li-ion cells for the Lander are listed, and results performance evaluation and cycle life performance tests are outlined for different temperatures. Cell charge characteristics are described, and test data is presented for charge capacity at varying temperatures. Capacity retention and storage characteristics tests are described and results are shown.

Daily Eating Patterns and Their Impact on Health and Disease.

PubMed

Zarrinpar, Amir; Chaix, Amandine; Panda, Satchidananda

2016-02-01

Cyclical expression of cell-autonomous circadian clock components and key metabolic regulators coordinate often discordant and distant cellular processes for efficient metabolism. Perturbation of these cycles, either by genetic manipulation, disruption of light/dark cycles, or, most relevant to the human population, via eating patterns, contributes to obesity and dysmetabolism. Time-restricted feeding (TRF), during which time of access to food is restricted to a few hours, without caloric restriction, supports robust metabolic cycles and protects against nutritional challenges that predispose to obesity and dysmetabolism. The mechanism by which TRF imparts its benefits is not fully understood but likely involves entrainment of metabolically active organs through gut signaling. Understanding the relationship of feeding pattern and metabolism could yield novel therapies for the obesity pandemic. Copyright © 2015. Published by Elsevier Ltd.

Daily Eating Patterns and Their Impact on Health and Disease

PubMed Central

Zarrinpar, Amir; Chaix, Amandine; Panda, Satchidananda

2016-01-01

Cyclical expression of cell-autonomous circadian clock components and key metabolic regulators coordinate often discordant and distant cellular processes for efficient metabolism. Perturbation of these cycles, either by genetic manipulation, disruption of light/dark cycles, or, most relevant to the human population, via eating patterns, contributes to obesity and dysmetabolism. Time-restricted feeding (TRF), during which time of access to food is restricted to a few hours, without caloric restriction, supports robust metabolic cycles and protects against nutritional challenges that predispose to obesity and dysmetabolism. The mechanism by which TRF imparts its benefits is not fully understood but likely involves entrainment of metabolically active organs through gut signaling. Understanding the relationship of feeding pattern and metabolism could yield novel therapies for the obesity pandemic. PMID:26706567

Circadian Clock Synchronization of the Cell Cycle in Zebrafish Occurs through a Gating Mechanism Rather Than a Period-phase Locking Process.

PubMed

Laranjeiro, Ricardo; Tamai, T Katherine; Letton, William; Hamilton, Noémie; Whitmore, David

2018-04-01

Studies from a number of model systems have shown that the circadian clock controls expression of key cell cycle checkpoints, thus providing permissive or inhibitory windows in which specific cell cycle events can occur. However, a major question remains: Is the clock actually regulating the cell cycle through such a gating mechanism or, alternatively, is there a coupling process that controls the speed of cell cycle progression? Using our light-responsive zebrafish cell lines, we address this issue directly by synchronizing the cell cycle in culture simply by changing the entraining light-dark (LD) cycle in the incubator without the need for pharmacological intervention. Our results show that the cell cycle rapidly reentrains to a shifted LD cycle within 36 h, with changes in p21 expression and subsequent S phase timing occurring within the first few hours of resetting. Reentrainment of mitosis appears to lag S phase resetting by 1 circadian cycle. The range of entrainment of the zebrafish clock to differing LD cycles is large, from 16 to 32 hour periods. We exploited this feature to explore cell cycle entrainment at both the population and single cell levels. At the population level, cell cycle length is shortened or lengthened under corresponding T-cycles, suggesting that a 1:1 coupling mechanism is capable of either speeding up or slowing down the cell cycle. However, analysis at the single cell level reveals that this, in fact, is not true and that a gating mechanism is the fundamental method of timed cell cycle regulation in zebrafish. Cell cycle length at the single cell level is virtually unaltered with varying T-cycles.

Circadian Clock Synchronization of the Cell Cycle in Zebrafish Occurs through a Gating Mechanism Rather Than a Period-phase Locking Process

PubMed Central

Tamai, T. Katherine; Letton, William; Hamilton, Noémie; Whitmore, David

2018-01-01

Studies from a number of model systems have shown that the circadian clock controls expression of key cell cycle checkpoints, thus providing permissive or inhibitory windows in which specific cell cycle events can occur. However, a major question remains: Is the clock actually regulating the cell cycle through such a gating mechanism or, alternatively, is there a coupling process that controls the speed of cell cycle progression? Using our light-responsive zebrafish cell lines, we address this issue directly by synchronizing the cell cycle in culture simply by changing the entraining light-dark (LD) cycle in the incubator without the need for pharmacological intervention. Our results show that the cell cycle rapidly reentrains to a shifted LD cycle within 36 h, with changes in p21 expression and subsequent S phase timing occurring within the first few hours of resetting. Reentrainment of mitosis appears to lag S phase resetting by 1 circadian cycle. The range of entrainment of the zebrafish clock to differing LD cycles is large, from 16 to 32 hour periods. We exploited this feature to explore cell cycle entrainment at both the population and single cell levels. At the population level, cell cycle length is shortened or lengthened under corresponding T-cycles, suggesting that a 1:1 coupling mechanism is capable of either speeding up or slowing down the cell cycle. However, analysis at the single cell level reveals that this, in fact, is not true and that a gating mechanism is the fundamental method of timed cell cycle regulation in zebrafish. Cell cycle length at the single cell level is virtually unaltered with varying T-cycles. PMID:29444612

The cell shape proteins MreB and MreC control cell morphogenesis by positioning cell wall synthetic complexes.

PubMed

Divakaruni, Arun V; Baida, Cyril; White, Courtney L; Gober, James W

2007-10-01

MreB, the bacterial actin homologue, is thought to function in spatially co-ordinating cell morphogenesis in conjunction with MreC, a protein that wraps around the outside of the cell within the periplasmic space. In Caulobacter crescentus, MreC physically associates with penicillin-binding proteins (PBPs) which catalyse the insertion of intracellularly synthesized precursors into the peptidoglycan cell wall. Here we show that MreC is required for the spatial organization of components of the peptidoglycan-synthesizing holoenzyme in the periplasm and MreB directs the localization of a peptidoglycan precursor synthesis protein in the cytosol. Additionally, fluorescent vancomycin (Van-FL) labelling revealed that the bacterial cytoskeletal proteins MreB and FtsZ, as well as MreC and RodA, were required for peptidoglycan synthetic activity. MreB and FtsZ were found to be required for morphogenesis of the polar stalk. FtsZ was required for a cell cycle-regulated burst of peptidoglycan synthesis early in the cell cycle resulting in the synthesis of cross-band structures, whereas MreB was required for lengthening of the stalk. Thus, the bacterial cytoskeleton and cell shape-determining proteins such as MreC, function in concert to orchestrate the localization of cell wall synthetic complexes resulting in spatially co-ordinated and efficient peptidoglycan synthetic activity.

Extracellular matrix functionalized microcavities to control hematopoietic stem and progenitor cell fate.

PubMed

Kurth, Ina; Franke, Katja; Pompe, Tilo; Bornhäuser, Martin; Werner, Carsten

2011-06-14

Polymeric microcavities functionalized with extracellular matrix components were used as an experimental in vitro model to investigate principles of hematopoietic stem and progenitor cell (HSPC) fate control. Using human CD133+ HSPC we could demonstrate distinct differences in HSPC cycling and differentiation dependence on the adhesion ligand specificity (i.e., heparin, collagen I) and cytokine levels. The presented microcavity platform provides a powerful in vitro approach to explore the role of exogenous cues in HSPC fate decisions and can therefore be instrumental to progress in stem cell biology and translational research toward new therapies. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Manganese Superoxide Dismutase: Guardian of the Powerhouse

PubMed Central

Holley, Aaron K.; Bakthavatchalu, Vasudevan; Velez-Roman, Joyce M.; St. Clair, Daret K.

2011-01-01

The mitochondrion is vital for many metabolic pathways in the cell, contributing all or important constituent enzymes for diverse functions such as β-oxidation of fatty acids, the urea cycle, the citric acid cycle, and ATP synthesis. The mitochondrion is also a major site of reactive oxygen species (ROS) production in the cell. Aberrant production of mitochondrial ROS can have dramatic effects on cellular function, in part, due to oxidative modification of key metabolic proteins localized in the mitochondrion. The cell is equipped with myriad antioxidant enzyme systems to combat deleterious ROS production in mitochondria, with the mitochondrial antioxidant enzyme manganese superoxide dismutase (MnSOD) acting as the chief ROS scavenging enzyme in the cell. Factors that affect the expression and/or the activity of MnSOD, resulting in diminished antioxidant capacity of the cell, can have extraordinary consequences on the overall health of the cell by altering mitochondrial metabolic function, leading to the development and progression of numerous diseases. A better understanding of the mechanisms by which MnSOD protects cells from the harmful effects of overproduction of ROS, in particular, the effects of ROS on mitochondrial metabolic enzymes, may contribute to the development of novel treatments for various diseases in which ROS are an important component. PMID:22072939

Involvement of multiple cellular pathways in regulating resistance to tamoxifen in BIK-suppressed MCF-7 cells.

PubMed

Viedma-Rodríguez, Rubí; Ruiz Esparza-Garrido, Ruth; Baiza-Gutman, Luis Arturo; Velázquez-Flores, Miguel Ángel; García-Carrancá, Alejandro; Salamanca-Gómez, Fabio; Arenas-Aranda, Diego

2015-09-01

Majority of women with estrogen receptor (ER)-positive breast cancers initially respond to hormone therapies such as tamoxifen (TAM; antagonist of estrogen). However, many tumors eventually become resistant to TAM. Therefore, understanding the various cellular components involved in causing resistance to TAM is of paramount importance in designing novel entities for efficacious hormone therapy. Previously, we found that suppression of BIK gene expression induced TAM resistance in MCF-7 breast cancer cells. In order to understand the response of these cells to TAM and its association with resistance, a microarray analysis of gene expression was performed in the BIK-suppressed MCF-7 cells and compared it to the TAM-only-treated cells (controls). Several genes participating in various cellular pathways were identified. Molecules identified in the drug resistance pathway were 14-3-3z or YWHAZ, WEE1, PRKACA, NADK, and HSP90AA 1. Further, genes involved in cell cycle control, apoptosis, and cell proliferation were also found differentially expressed in these cells. Transcriptional and translational analysis of key molecules such as STAT2, AKT 3, and 14-3-3z revealed similar changes at the messenger RNA (mRNA) as well as at the protein level. Importantly, there was no cytotoxic effect of TAM on BIK-suppressed MCF-7 cells. Further, these cells were not arrested at the G0-G1 phase of the cell cycle although 30 % of BIK-suppressed cells were arrested at the G2 phase of the cycle on TAM treatment. Furthermore, we found a relevant interaction between 14-3-3z and WEE1, suggesting that the cytotoxic effect of TAM was prevented in BIK-suppressed cells because this interaction leads to transitory arrest in the G2 phase leading to the repair of damaged DNA and allowing the cells to proliferate.

Cell-cycle-dependent three-dimensional redistribution of nuclear proteins, P 120, pKi-67, and SC 35 splicing factor, in the presence of the topoisomerase I inhibitor camptothecin.

PubMed

Elias, Emmanuel; Lalun, Nathalie; Lorenzato, Marianne; Blache, Laurent; Chelidze, Pavel; O'Donohue, Marie-Françoise; Ploton, Dominique; Bobichon, Hélène

2003-11-15

Topoisomerase I (Topo I) is mostly known for its role in DNA relaxation, which is required for duplication and transcription. Topo I acts as a protein kinase mainly directed to the mRNA splicing factor SC35. Camptothecin is one of the specific Topo I inhibitors and is effective on the two functions of the enzyme. In this study we demonstrated that treatment of KB cells with camptothecin for only 30 min induced the 3D reorganization and redistribution of three proteins involved in the nucleus machinery, P 120, pKi-67, and SC 35, and this occurred in a cell cycle-dependent manner. Our data were obtained from confocal microscopic studies after immunolabeling, 3D reconstruction, and measurement of the nuclear components volumes. In the presence of camptothecin, P 120, which occupied the nucleolar volume, lost its reticulation and pKi-67 was redistributed within the nucleoplasm and even into the cytoplasm. Finally, for SC 35 the fusion of its dots into bigger volumes was observed specifically during the G1 phase. Variations of volumes were also observed for the nucleolus and for the nucleus. These results pointed out that, depending on the cell cycle phase, Topo I functions were selective toward the three different proteins.

γ-Oryzanol reduces caveolin-1 and PCGEM1 expression, markers of aggressiveness in prostate cancer cell lines.

PubMed

Hirsch, Gabriela E; Parisi, Mariana M; Martins, Leo A M; Andrade, Claudia M B; Barbé-Tuana, Florencia M; Guma, Fátima T C R

2015-06-01

Prostate cancer is a leading cause of death among men due to the limited number of treatment strategies available for advanced disease. γ-oryzanol is a component of rice bran, rich in phytosterols, known for its antioxidant, anti-carcinogenic and endocrinological effects. It is known that γ-oryzanol may affect prostate cancer cells through the down regulation of the antioxidant genes and that phytosterols have anti-proliferative and apoptotic effects. There are evidences showing that some of the components of γ-oryzanol can modulate genes involved in the development and progression of prostate cancer, as caveolin-1 (Cav-1) and prostate specific androgen-regulated gene (PCGEM1). To determine the effects of γ-oryzanol on prostate cancer cell survival we evaluated the cell viability and biomass by MTT and sulforhodamine B assays, respectively. Cell death, cell cycle and pERK1/2 activity were assessed by flow cytometry. The changes in gene expression involved in the survival and progression of prostate cancer cav-1 and PCGEM1 genes were evaluated by quantitative real time reverse transcriptase polymerase chain reaction (RT-PCR) and cav-1 protein by immunofluorescence followed by confocal microscopy analysis. We found that γ-oryzanol decreases cell viability and culture biomass by apoptosis and/or necrosis death in androgen unresponsive (PC3 and DU145) and responsive (LNCaP) cell lines, and signals through pERK1/2 in LNCaP and DU145 cells. γ-oryzanol also appears to block cell cycle progression at the G2/M in PC3 and LNCaP cells and at G0/G1 in DU145 cells. These effects were accompanied by a down regulation in the expression of the cav-1 in both androgen unresponsive cell lines and PCGEM1 gene in DU145 and LNCaP cells. In summary, we used biochemical and genetics approaches to demonstrate that γ-oryzanol show a promising adjuvant role in the treatment of prostate cancer. © 2015 Wiley Periodicals, Inc.

Kit signaling inhibits the sphingomyelin-ceramide pathway through PLC gamma 1: implication in stem cell factor radioprotective effect.

PubMed

Maddens, Stéphane; Charruyer, Alexandra; Plo, Isabelle; Dubreuil, Patrice; Berger, Stuart; Salles, Bernard; Laurent, Guy; Jaffrézou, Jean-Pierre

2002-08-15

Previous studies demonstrated that Kit activation confers radioprotection. However, the mechanism by which Kit signaling interferes with cellular response to ionizing radiation (IR) has not been firmly established. Based on the role of the sphingomyelin (SM) cycle apoptotic pathway in IR-induced apoptosis, we hypothesized that one of the Kit signaling components might inhibit IR-induced ceramide production or ceramide-induced apoptosis. Results show that, in both Ba/F3 and 32D murine cell lines transfected with wild-type c-kit, stem cell factor (SCF) stimulation resulted in a significant reduction of IR-induced apoptosis and cytotoxicity, whereas DNA repair remained unaffected. Moreover, SCF stimulation inhibited IR-induced neutral sphingomyelinase (N-SMase) stimulation and ceramide production. The SCF inhibitory effect on SM cycle was not influenced by wortmannin, a phosphoinositide-3 kinase (PI3K) inhibitor. The SCF protective effect was maintained in 32D-KitYF719 cells in which the PI3K/Akt signaling pathway is abolished due to mutation in Kit docking site for PI3K. In contrast, phospholipase C gamma (PLC gamma) inhibition by U73122 totally restored IR-induced N-SMase stimulation, ceramide production, and apoptosis in Kit-activated cells. Moreover, SCF did not protect 32D-KitYF728 cells (lacking a functional docking site for PLC gamma 1), from IR-induced SM cycle. Finally, SCF-induced radioprotection of human CD34(+) bone marrow cells was also inhibited by U73122. Altogether, these results suggest that SCF radioprotection is due to PLC gamma 1-dependent negative regulation of IR-induced N-SMase stimulation. Beyond the scope of Kit-expressing cells, it suggests that PLC gamma 1 status could greatly influence the post-DNA damage cellular response to IR, and perhaps, to other genotoxic agents.

Inhibition of serine/threonine phosphatase PP2A enhances cancer chemotherapy by blocking DNA damage induced defense mechanisms.

PubMed

Lu, Jie; Kovach, John S; Johnson, Francis; Chiang, Jeffrey; Hodes, Richard; Lonser, Russell; Zhuang, Zhengping

2009-07-14

A variety of mechanisms maintain the integrity of the genome in the face of cell stress. Cancer cell response to chemotherapeutic and radiation-induced DNA damage is mediated by multiple defense mechanisms including polo-like kinase 1 (Plk-1), protein kinase B (Akt-1), and/or p53 pathways leading to either apoptosis or cell cycle arrest. Subsequently, a subpopulation of arrested viable cancer cells may remain and recur despite aggressive and repetitive therapy. Here, we show that modulation (activation of Akt-1 and Plk-1 and repression of p53) of these pathways simultaneously results in paradoxical enhancement of the effectiveness of cytotoxic chemotherapy. We demonstrate that a small molecule inhibitor, LB-1.2, of protein phosphatase 2A (PP2A) activates Plk-1 and Akt-1 and decreases p53 abundance in tumor cells. Combined with temozolomide (TMZ; a DNA-methylating chemotherapeutic drug), LB-1.2 causes complete regression of glioblastoma multiforme (GBM) xenografts without recurrence in 50% of animals (up to 28 weeks) and complete inhibition of growth of neuroblastoma (NB) xenografts. Treatment with either drug alone results in only short-term inhibition/regression with all xenografts resuming rapid growth. Combined with another widely used anticancer drug, Doxorubicin (DOX, a DNA intercalating agent), LB-1.2 also causes marked GBM xenograft regression, whereas DOX alone only slows growth. Inhibition of PP2A by LB-1.2 blocks cell-cycle arrest and increases progression of cell cycle in the presence of TMZ or DOX. Pharmacologic inhibition of PP2A may be a general method for enhancing the effectiveness of cancer treatments that damage DNA or disrupt components of cell replication.

Space Environment Testing of Photovoltaic Array Systems at NASA's Marshall Space Flight Center

NASA Technical Reports Server (NTRS)

Phillips, Brandon S.; Schneider, Todd A.; Vaughn, Jason A.; Wright, Kenneth H., Jr.

2015-01-01

To successfully operate a photovoltaic (PV) array system in space requires planning and testing to account for the effects of the space environment. It is critical to understand space environment interactions not only on the PV components, but also the array substrate materials, wiring harnesses, connectors, and protection circuitry (e.g. blocking diodes). Key elements of the space environment which must be accounted for in a PV system design include: Solar Photon Radiation, Charged Particle Radiation, Plasma, and Thermal Cycling. While solar photon radiation is central to generating power in PV systems, the complete spectrum includes short wavelength ultraviolet components, which photo-ionize materials, as well as long wavelength infrared which heat materials. High energy electron radiation has been demonstrated to significantly reduce the output power of III-V type PV cells; and proton radiation damages material surfaces - often impacting coverglasses and antireflective coatings. Plasma environments influence electrostatic charging of PV array materials, and must be understood to ensure that long duration arcs do not form and potentially destroy PV cells. Thermal cycling impacts all components on a PV array by inducing stresses due to thermal expansion and contraction. Given such demanding environments, and the complexity of structures and materials that form a PV array system, mission success can only be ensured through realistic testing in the laboratory. NASA's Marshall Space Flight Center has developed a broad space environment test capability to allow PV array designers and manufacturers to verify their system's integrity and avoid costly on-orbit failures. The Marshall Space Flight Center test capabilities are available to government, commercial, and university customers. Test solutions are tailored to meet the customer's needs, and can include performance assessments, such as flash testing in the case of PV cells.

Human TREX2 components PCID2 and centrin 2, but not ENY2, have distinct functions in protein export and co-localize to the centrosome.

PubMed

Cunningham, Corey N; Schmidt, Casey A; Schramm, Nathaniel J; Gaylord, Michelle R; Resendes, Karen K

2014-01-15

TREX-2 is a five protein complex, conserved from yeast to humans, involved in linking mRNA transcription and export. The centrin 2 subunit of TREX-2 is also a component of the centrosome and is additionally involved in a distinctly different process of nuclear protein export. While centrin 2 is a known multifunctional protein, the roles of other human TREX-2 complex proteins other than mRNA export are not known. In this study, we found that human TREX-2 member PCID2 but not ENY2 is involved in some of the same cellular processes as those of centrin 2 apart from the classical TREX-2 function. PCID2 is present at the centrosome in a subset of HeLa cells and this localization is centrin 2 dependent. Furthermore, the presence of PCID2 at the centrosome is prevalent throughout the cell cycle as determined by co-staining with cyclins E, A and B. PCID2 but not ENY2 is also involved in protein export. Surprisingly, siRNA knockdown of PCID2 delayed the rate of nuclear protein export, a mechanism distinct from the effects of centrin 2, which when knocked down inhibits export. Finally we showed that co-depletion of centrin 2 and PCID2 leads to blocking rather than delaying nuclear protein export, indicating the dominance of the centrin 2 phenotype. Together these results represent the first discovery of specific novel functions for PCID2 other than mRNA export and suggest that components of the TREX-2 complex serve alternative shared roles in the regulation of nuclear transport and cell cycle progression. © 2013 Published by Elsevier Inc.

2',4'-dihydroxychalcone, a flavonoid isolated from Herba oxytropis, suppresses PC-3 human prostate cancer cell growth by induction of apoptosis.

PubMed

Sheng, Yuqing; Zou, Mingchang; Wang, Yan; Li, Qiheng

2015-12-01

Natural products are a promising source for the development of novel cancer therapies, due to their potential effectiveness and low toxicity profiles. As a main component of Herba oxytropis , 2',4'-dihydroxychalcone (TFC) is known to demonstrate anti-tumor activity in vitro . In the present study, TFC was found to potently inhibit proliferation and induce apoptosis in PC-3 human prostate cancer cells in a dose-dependent manner. The results demonstrated that the induction of apoptosis is associated with cell cycle arrest at the G0/G1 phase and activation of caspase-3/-7. Additional mechanistic studies of two biomarkers, phosphatase and tensin homolog (PTEN) and cyclin-dependent kinase inhibitor 1B (p27 Kip1 ), in prostate cancer revealed that TFC treatment significantly upregulated the expression of PTEN and p27 Kip1 . The findings of the present study indicate that TFC-induced apoptosis in PC-3 cells via upregulation of PTEN and p27 Kip1 , which results in cell cycle arrest in G0/G1 phase, activation of caspase-3/-7 and induction of apoptosis. Therefore, TFC may be a potential compound for human prostate cancer therapy.

Fresh WNT into the regulation of mitosis.

PubMed

Stolz, Ailine; Bastians, Holger

2015-01-01

Canonical Wnt signaling triggering β-catenin-dependent gene expression contributes to cell cycle progression, in particular at the G1/S transition. Recently, however, it became clear that the cell cycle can also feed back on Wnt signaling at the G2/M transition. This is illustrated by the fact that mitosis-specific cyclin-dependent kinases can phosphorylate the Wnt co-receptor LRP6 to prime the pathway for incoming Wnt signals when cells enter mitosis. In addition, there is accumulating evidence that various Wnt pathway components might exert additional, Wnt-independent functions that are important for proper regulation of mitosis. The importance of Wnt pathways during mitosis was most recently enforced by the discovery of Wnt signaling contributing to the stabilization of proteins other than β-catenin, specifically at G2/M and during mitosis. This Wnt-mediated stabilization of proteins, now referred to as Wnt/STOP, might on one hand contribute to maintaining a critical cell size required for cell division and, on the other hand, for the faithful execution of mitosis itself. In fact, most recently we have shown that Wnt/STOP is required for ensuring proper microtubule dynamics within mitotic spindles, which is pivotal for accurate chromosome segregation and for the maintenance of euploidy.

Chemotherapy for management of localised high-grade gastric B-cell lymphoma: how much is necessary?

PubMed

Raderer, M; Chott, A; Drach, J; Montalban, C; Dragosics, B; Jäger, U; Püspök, A; Osterreicher, C; Zielinski, C C

2002-07-01

Recent data suggest that chemotherapy with the cyclophosphamide, doxorubicin, vincristine and prednisone (CHOP) regimen is a highly effective treatment for localised primary gastric lymphoma of diffuse large B-cell histology (DLBCL). We have reported that the large majority of patients achieve complete remission (CR) following three cycles of treatment, and now provide an updated series with special emphasis on patients receiving only short-term chemotherapy. All patients with a histologically verified diagnosis of gastric DLBCL in stages EI and EII(1) undergoing chemotherapy with the CHOP regimen were evaluated. Data analysed included clinical stage, histology [presence of an additional mucosa-associated lymphoid tissue (MALT) component], evidence of Helicobacter pylori infection, H. pylori eradication, time to CR, survival and regular restaging (i.e. after three and six cycles, respectively). A total of 37 patients with DLBCL of the stomach with localised disease were identified, five of whom also had a MALT component. Twenty-two patients presented with stage EI and 15 with stage EII(1) disease. All patients were given chemotherapy as sole management of their lymphoma; 36 patients received CHOP, while one patient was given CHOP along with rituximab. Thirty-two (86%) achieved a CR after a maximum of three cycles, while only four patients had to be given six cycles for CR. In total, nine of 37 patients (24%) discontinued therapy earlier than scheduled: one patient received one cycle, two received two, six received three and one patient received four cycles. Two of these patients stopped treatment due to toxicity, i.e. protracted thrombocytopenia or chemotherapy extravasation. One additional patient died after one cycle of treatment; autopsy disclosed no signs of remaining lymphoma. Three patients have died after a median follow-up of 39 months (including the one patient who discontinued therapy after one cycle of treatment), while the remaining 34 patients are alive without evidence of disease. Twenty-four out of 37 patients (65%) had also undergone H. pylori eradication (including six of nine patients receiving only short-term treatment). DLBCL of the stomach appears to be a highly chemosensitive disease. Our data question the need for full-term CHOP treatment in patients achieving CR upon first follow-up. However, recent data suggest that additional H. pylori eradication might have contributed to the excellent results achieved in our series.

Mussel-Inspired Conductive Polymer Binder for Si-Alloy Anode in Lithium-Ion Batteries

DOE PAGES

Zhao, Hui; Wei, Yang; Wang, Cheng; ...

2018-01-15

The excessive volume changes during cell cycling of Si-based anode in lithium ion batteries impeded its application. One major reason for the cell failure is particle isolation during volume shrinkage in delithiation process, which makes strong adhesion between polymer binder and anode active material particles a highly desirable property. Here, a biomimetic side-chain conductive polymer incorporating catechol, a key adhesive component of the mussel holdfast protein, was synthesized. Atomic force microscopy-based single-molecule force measurements of mussel-inspired conductive polymer binder contacting a silica surface revealed a similar adhesion toward substrate when compared with an effective Si anode binder, homo-poly(acrylic acid), withmore » the added benefit of being electronically conductive. Electrochemical experiments showed a very stable cycling of Si-alloy anodes realized via this biomimetic conducting polymer binder, leading to a high loading Si anode with a good rate performance. We attribute the ability of the Si-based anode to tolerate the volume changes during cycling to the excellent mechanical integrity afforded by the strong interfacial adhesion of the biomimetic conducting polymer.« less

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

PubMed

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

2013-03-01

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

Linalool, a Piper aduncum essential oil component, has selective activity against Trypanosoma cruzi trypomastigote forms at 4°C

PubMed Central

Villamizar, Luz Helena; Cardoso, Maria das Graças; de Andrade, Juliana; Teixeira, Maria Luisa; Soares, Maurilio José

2017-01-01

BACKGROUND Recent studies showed that essential oils from different pepper species (Piper spp.) have promising leishmanicidal and trypanocidal activities. OBJECTIVES In search for natural compounds against Trypanosoma cruzi, different forms of the parasite were incubated for 24 h at 28ºC or 4ºC with Piper aduncum essential oil (PaEO) or its main constituents linalool and nerolidol. METHODS PaEO chemical composition was obtained by GC-MS. Drug activity assays were based on cell counting, MTT data or infection index values. The effect of PaEO on the T. cruzi cell cycle and mitochondrial membrane potential was evaluated by flow cytometry. FINDINGS PaEO was effective against cell-derived (IC50/24 h: 2.8 μg/mL) and metacyclic (IC50/24 h: 12.1 μg/mL) trypomastigotes, as well as intracellular amastigotes (IC50/24 h: 9 μg/mL). At 4ºC - the temperature of red blood cells (RBCs) storage in blood banks - cell-derived trypomastigotes were more sensitive to PaEO (IC50/24 h = 3.8 μg/mL) than to gentian violet (IC50/24 h = 24.7 mg/mL). Cytotoxicity assays using Vero cells (37ºC) and RBCs (4ºC) showed that PaEO has increased selectivity for cell-derived trypomastigotes. Flow cytometry analysis showed that PaEO does not affect the cell cycle of T. cruzi epimastigotes, but decreases their mitochondrial membrane potential. GC-MS data identified nerolidol and linalool as major components of PaEO, and linalool had trypanocidal effect (IC50/24 h: 306 ng/mL) at 4ºC. MAIN CONCLUSION The trypanocidal effect of PaEO is likely due to the presence of linalool, which may represent an interesting candidate for use in the treatment of potentially contaminated RBCs bags at low temperature. PMID:28177047

Linalool, a Piper aduncum essential oil component, has selective activity against Trypanosoma cruzi trypomastigote forms at 4°C.

PubMed

Villamizar, Luz Helena; Cardoso, Maria das Graças; Andrade, Juliana de; Teixeira, Maria Luisa; Soares, Maurilio José

2017-02-01

Recent studies showed that essential oils from different pepper species (Piper spp.) have promising leishmanicidal and trypanocidal activities. In search for natural compounds against Trypanosoma cruzi, different forms of the parasite were incubated for 24 h at 28ºC or 4ºC with Piper aduncum essential oil (PaEO) or its main constituents linalool and nerolidol. PaEO chemical composition was obtained by GC-MS. Drug activity assays were based on cell counting, MTT data or infection index values. The effect of PaEO on the T. cruzi cell cycle and mitochondrial membrane potential was evaluated by flow cytometry. PaEO was effective against cell-derived (IC50/24 h: 2.8 μg/mL) and metacyclic (IC50/24 h: 12.1 μg/mL) trypomastigotes, as well as intracellular amastigotes (IC50/24 h: 9 μg/mL). At 4ºC - the temperature of red blood cells (RBCs) storage in blood banks - cell-derived trypomastigotes were more sensitive to PaEO (IC50/24 h = 3.8 μg/mL) than to gentian violet (IC50/24 h = 24.7 mg/mL). Cytotoxicity assays using Vero cells (37ºC) and RBCs (4ºC) showed that PaEO has increased selectivity for cell-derived trypomastigotes. Flow cytometry analysis showed that PaEO does not affect the cell cycle of T. cruzi epimastigotes, but decreases their mitochondrial membrane potential. GC-MS data identified nerolidol and linalool as major components of PaEO, and linalool had trypanocidal effect (IC50/24 h: 306 ng/mL) at 4ºC. The trypanocidal effect of PaEO is likely due to the presence of linalool, which may represent an interesting candidate for use in the treatment of potentially contaminated RBCs bags at low temperature.

Cytotoxic and phytotoxic effects of the main chemical components of spent pot-liner: a comparative approach.

PubMed

Palmieri, Marcel José; Luber, Jaquelini; Andrade-Vieira, Larissa Fonseca; Davide, Lisete Chamma

2014-03-15

Spent pot-liner (SPL) is a hazardous solid waste produced by the aluminum industry. Although its composition may vary, fluoride and cyanide salts as well as aluminum are predominant components. A seed-germination and root-elongation test was performed with Lactuca sativa seeds as a test system. SPL induced decrease of seed germination rate and root elongation. The concentration of 26.5g/L SPL was established from a regression curve as the IC50 (inhibition concentration 50%). Through chemical analyses, the concentrations of fluoride, cyanide and aluminum in SPL solutions of 26.5g/L (IC50), 39.75g/L (1.5IC50) and 13.25g/L (0.5IC50) were determined. Further, a cell-cycle test was conducted with root tips of L. sativa exposed to these same SPL solutions. All test chemicals presented toxic effects on meristematic cells of L. sativa. Aluminum was identified as the SPL component mainly responsible for reduction of the mitotic index. Chromosomal alterations resulted from the interactions among the three main chemical components of SPL, without a clear predominantly responsible agent. Induction of condensed nuclei was mainly due to effects of aluminum and fluoride, and may serve as an indicator of induced cell death. Copyright © 2014 Elsevier B.V. All rights reserved.

Cellular metabolic responses of the marine diatom Pseudo-nitzschia multiseries associated with cell wall formation.

PubMed

Xu, Bin; Luo, Chun-Shan; Liang, Jun-Rong; Chen, Dan-Dan; Zhuo, Wen-Hao; Gao, Ya-Hui; Chen, Chang-Ping; Song, Si-Si

2014-08-01

In this study a comparative proteomics approach involving a mass spectrometric analysis of synchronized cells was employed to investigate the cellular-level metabolic mechanisms associated with siliceous cell wall formation in the pennate diatom Pseudo-nitzschia multiseries. Cultures of P. multiseries were synchronized using the silicate limitation method. Approximately 75% of cells were arrested at the G2+M phase of the cell cycle after 48 h of silicate starvation. The majority of cells progressed to new valve synthesis within 5h of silicon replenishment. We compared the proteome of P. multiseries at 0, 4, 5, and 6h of synchronization progress upon silicon replenishment using two-dimensional gel electrophoresis. Forty-eight differentially expressed protein spots were identified in abundance (greater than two-fold change; P<0.005), some of which are predicted to be involved in intracellular trafficking, cytoskeleton, photosynthesis, lipid metabolism, and protein biosynthesis. Cytoskeleton proteins and clathrin coat components were also hypothesized to play potential roles in cell wall formation. The proteomic profile analysis suggests that P. multiseries most likely employs multiple synergistic biochemical mechanisms for cell wall formation. These results improve our understanding of the molecular mechanisms underlying silicon cell wall formation and enhance our understanding of the important role played by diatoms in silicon biogeochemical cycling. Copyright © 2013 Elsevier B.V. All rights reserved.

A map of protein dynamics during cell-cycle progression and cell-cycle exit

PubMed Central

Gookin, Sara; Min, Mingwei; Phadke, Harsha; Chung, Mingyu; Moser, Justin; Miller, Iain; Carter, Dylan

2017-01-01

The cell-cycle field has identified the core regulators that drive the cell cycle, but we do not have a clear map of the dynamics of these regulators during cell-cycle progression versus cell-cycle exit. Here we use single-cell time-lapse microscopy of Cyclin-Dependent Kinase 2 (CDK2) activity followed by endpoint immunofluorescence and computational cell synchronization to determine the temporal dynamics of key cell-cycle proteins in asynchronously cycling human cells. We identify several unexpected patterns for core cell-cycle proteins in actively proliferating (CDK2-increasing) versus spontaneously quiescent (CDK2-low) cells, including Cyclin D1, the levels of which we find to be higher in spontaneously quiescent versus proliferating cells. We also identify proteins with concentrations that steadily increase or decrease the longer cells are in quiescence, suggesting the existence of a continuum of quiescence depths. Our single-cell measurements thus provide a rich resource for the field by characterizing protein dynamics during proliferation versus quiescence. PMID:28892491

Curcumin-treated cancer cells show mitotic disturbances leading to growth arrest and induction of senescence phenotype.

PubMed

Mosieniak, Grażyna; Sliwinska, Małgorzata A; Przybylska, Dorota; Grabowska, Wioleta; Sunderland, Piotr; Bielak-Zmijewska, Anna; Sikora, Ewa

2016-05-01

Cellular senescence is recognized as a potent anticancer mechanism that inhibits carcinogenesis. Cancer cells can also undergo senescence upon chemo- or radiotherapy. Curcumin, a natural polyphenol derived from the rhizome of Curcuma longa, shows anticancer properties both in vitro and in vivo. Previously, we have shown that treatment with curcumin leads to senescence of human cancer cells. Now we identified the molecular mechanism underlying this phenomenon. We observed a time-dependent accumulation of mitotic cells upon curcumin treatment. The time-lapse analysis proved that those cells progressed through mitosis for a significantly longer period of time. A fraction of cells managed to divide or undergo mitotic slippage and then enter the next phase of the cell cycle. Cells arrested in mitosis had an improperly formed mitotic spindle and were positive for γH2AX, which shows that they acquired DNA damage during prolonged mitosis. Moreover, the DNA damage response pathway was activated upon curcumin treatment and the components of this pathway remained upregulated while cells were undergoing senescence. Inhibition of the DNA damage response decreased the number of senescent cells. Thus, our studies revealed that the induction of cell senescence upon curcumin treatment resulted from aberrant progression through the cell cycle. Moreover, the DNA damage acquired by cancer cells, due to mitotic disturbances, activates an important molecular mechanism that determines the potential anticancer activity of curcumin. Copyright © 2016 Elsevier Ltd. All rights reserved.

Regulatory networks and connected components of the neutral space. A look at functional islands

NASA Astrophysics Data System (ADS)

Boldhaus, G.; Klemm, K.

2010-09-01

The functioning of a living cell is largely determined by the structure of its regulatory network, comprising non-linear interactions between regulatory genes. An important factor for the stability and evolvability of such regulatory systems is neutrality - typically a large number of alternative network structures give rise to the necessary dynamics. Here we study the discretized regulatory dynamics of the yeast cell cycle [Li et al., PNAS, 2004] and the set of networks capable of reproducing it, which we call functional. Among these, the empirical yeast wildtype network is close to optimal with respect to sparse wiring. Under point mutations, which establish or delete single interactions, the neutral space of functional networks is fragmented into ≈ 4.7 × 108 components. One of the smaller ones contains the wildtype network. On average, functional networks reachable from the wildtype by mutations are sparser, have higher noise resilience and fewer fixed point attractors as compared with networks outside of this wildtype component.

Curcumin Inhibits Rift Valley Fever Virus Replication in Human Cells*

PubMed Central

Narayanan, Aarthi; Kehn-Hall, Kylene; Senina, Svetlana; Lundberg, Lindsay; Van Duyne, Rachel; Guendel, Irene; Das, Ravi; Baer, Alan; Bethel, Laura; Turell, Michael; Hartman, Amy Lynn; Das, Bhaskar; Bailey, Charles; Kashanchi, Fatah

2012-01-01

Rift Valley fever virus (RVFV) is an arbovirus that is classified as a select agent, an emerging infectious virus, and an agricultural pathogen. Understanding RVFV-host interactions is imperative to the design of novel therapeutics. Here, we report that an infection by the MP-12 strain of RVFV induces phosphorylation of the p65 component of the NFκB cascade. We demonstrate that phosphorylation of p65 (serine 536) involves phosphorylation of IκBα and occurs through the classical NFκB cascade. A unique, low molecular weight complex of the IKK-β subunit can be observed in MP-12-infected cells, which we have labeled IKK-β2. The IKK-β2 complex retains kinase activity and phosphorylates an IκBα substrate. Inhibition of the IKK complex using inhibitors impairs viral replication, thus alluding to the requirement of an active IKK complex to the viral life cycle. Curcumin strongly down-regulates levels of extracellular infectious virus. Our data demonstrated that curcumin binds to and inhibits kinase activity of the IKK-β2 complex in infected cells. Curcumin partially exerts its inhibitory influence on RVFV replication by interfering with IKK-β2-mediated phosphorylation of the viral protein NSs and by altering the cell cycle of treated cells. Curcumin also demonstrated efficacy against ZH501, the fully virulent version of RVFV. Curcumin treatment down-regulated viral replication in the liver of infected animals. Our data point to the possibility that RVFV infection may result in the generation of novel versions of host components (such as IKK-β2) that, by virtue of altered protein interaction and function, qualify as unique therapeutic targets. PMID:22847000

The Role of Isocitrate Lyase (ICL1) in the Metabolic Adaptation of Candida albicans Biofilms

PubMed Central

Ishola, Oluwaseun Ayodeji; Ting, Seng Yeat; Tabana, Yasser M; Ahmed, Mowaffaq Adam; Yunus, Muhammad Amir; Mohamed, Rafeezul; Lung Than, Leslie Thian; Sandai, Doblin

2016-01-01

Background A major characteristic of Candida biofilm cells that differentiates them from free-floating cells is their high tolerance to antifungal drugs. This high resistance is attributed to particular biofilm properties, including the accumulation of extrapolymeric substances, morphogenetic switching, and metabolic flexibility. Objectives This study evaluated the roles of metabolic processes (in particular the glyoxylate cycle) on biofilm formation, antifungal drug resistance, morphology, and cell wall components. Methods Growth, adhesion, biofilm formation, and cell wall carbohydrate composition were quantified for isogenic Candida albicans ICL1/ICL1, ICL1/icl1, and icl1/icl1 strains. The morphology and topography of these strains were compared by light microscopy and scanning electron microscopy. FKS1 (glucan synthase), ERG11 (14-α-demethylase), and CDR2 (efflux pump) mRNA levels were quantified using qRT-PCR. Results The ICL1/icl1 and icl1/icl1 strains formed similar biofilms and exhibited analogous drug-tolerance levels to the control ICL1/ICL1 strains. Furthermore, the drug sequestration ability of β-1, 3-glucan, a major carbohydrate component of the extracellular matrix, was not impaired. However, the inactivation of ICL1 did impair morphogenesis. ICL1 deletion also had a considerable effect on the expression of the FKS1, ERG11, and CDR2 genes. FKS1 and ERG11 were upregulated in ICL1/icl1 and icl1/icl1 cells throughout the biofilm developmental stages, and CDR2 was upregulated at the early phase. However, their expression was downregulated compared to the control ICL1/ICL1 strain. Conclusions We conclude that the glyoxylate cycle is not a specific determinant of biofilm drug resistance. PMID:27800147

Cell division cycle 45 promotes papillary thyroid cancer progression via regulating cell cycle.

PubMed

Sun, Jing; Shi, Run; Zhao, Sha; Li, Xiaona; Lu, Shan; Bu, Hemei; Ma, Xianghua

2017-05-01

Cell division cycle 45 was reported to be overexpressed in some cancer-derived cell lines and was predicted to be a candidate oncogene in cervical cancer. However, the clinical and biological significance of cell division cycle 45 in papillary thyroid cancer has never been investigated. We determined the expression level and clinical significance of cell division cycle 45 using The Cancer Genome Atlas, quantitative real-time polymerase chain reaction, and immunohistochemistry. A great upregulation of cell division cycle 45 was observed in papillary thyroid cancer tissues compared with adjacent normal tissues. Furthermore, overexpression of cell division cycle 45 positively correlates with more advanced clinical characteristics. Silence of cell division cycle 45 suppressed proliferation of papillary thyroid cancer cells via G1-phase arrest and inducing apoptosis. The oncogenic activity of cell division cycle 45 was also confirmed in vivo. In conclusion, cell division cycle 45 may serve as a novel biomarker and a potential therapeutic target for papillary thyroid cancer.

Circadian physiology of metabolism.

PubMed

Panda, Satchidananda

2016-11-25

A majority of mammalian genes exhibit daily fluctuations in expression levels, making circadian expression rhythms the largest known regulatory network in normal physiology. Cell-autonomous circadian clocks interact with daily light-dark and feeding-fasting cycles to generate approximately 24-hour oscillations in the function of thousands of genes. Circadian expression of secreted molecules and signaling components transmits timing information between cells and tissues. Such intra- and intercellular daily rhythms optimize physiology both by managing energy use and by temporally segregating incompatible processes. Experimental animal models and epidemiological data indicate that chronic circadian rhythm disruption increases the risk of metabolic diseases. Conversely, time-restricted feeding, which imposes daily cycles of feeding and fasting without caloric reduction, sustains robust diurnal rhythms and can alleviate metabolic diseases. These findings highlight an integrative role of circadian rhythms in physiology and offer a new perspective for treating chronic diseases in which metabolic disruption is a hallmark. Copyright © 2016, American Association for the Advancement of Science.

Repair of DNA Damage Induced by the Cytidine Analog Zebularine Requires ATR and ATM in Arabidopsis[OPEN

PubMed Central

Liu, Chun-Hsin; Finke, Andreas; Díaz, Mariana; Rozhon, Wilfried; Poppenberger, Brigitte; Baubec, Tuncay; Pecinka, Ales

2015-01-01

DNA damage repair is an essential cellular mechanism that maintains genome stability. Here, we show that the nonmethylable cytidine analog zebularine induces a DNA damage response in Arabidopsis thaliana, independent of changes in DNA methylation. In contrast to genotoxic agents that induce damage in a cell cycle stage-independent manner, zebularine induces damage specifically during strand synthesis in DNA replication. The signaling of this damage is mediated by additive activity of ATAXIA TELANGIECTASIA MUTATED AND RAD3-RELATED and ATAXIA TELANGIECTASIA MUTATED kinases, which cause postreplicative cell cycle arrest and increased endoreplication. The repair requires a functional STRUCTURAL MAINTENANCE OF CHROMOSOMES5 (SMC5)-SMC6 complex and is accomplished predominantly by synthesis-dependent strand-annealing homologous recombination. Here, we provide insight into the response mechanism for coping with the genotoxic effects of zebularine and identify several components of the zebularine-induced DNA damage repair pathway. PMID:26023162

Corrosion of simulated bearing components of three bearing steels in the presence of chloride-contaminated lubricant

NASA Technical Reports Server (NTRS)

Parker, R. J.; Bamberger, E. N.; Nahm, A. H.

1983-01-01

Corrosion tests were run with AISI 52100, AISI M-50 and AMS 5794 under conditions that simulate the crevice corrosion found in aircraft ball and roller bearings rejected at overhaul for corrosion. Test specimens were fabricated that simulated the contacts of balls or rollers and the raceways. Corrosion cells were assembled in the presence of a lubricant contaminated with water and chloride ions. The cell was then thermally cycled between 339 K (150 F) and 276 K (37 F). The corrosion observed after 14 cycles was that of crevice and pitting corrosion typically found in aircraft bearings. AMS 5749 showed a very slight amount of corrosion. No appreciable differences were noted between AISI 52100 and AISI M-50, but both showed much greater corrosion than AMS 5749. The corrosion pits observed in AISI M-50 appeared to be fewer in number but generally deeper and larger than in AISI 52100.

Landscape and flux reveal a new global view and physical quantification of mammalian cell cycle

PubMed Central

Li, Chunhe; Wang, Jin

2014-01-01

Cell cycles, essential for biological function, have been investigated extensively. However, enabling a global understanding and defining a physical quantification of the stability and function of the cell cycle remains challenging. Based upon a mammalian cell cycle gene network, we uncovered the underlying Mexican hat landscape of the cell cycle. We found the emergence of three local basins of attraction and two major potential barriers along the cell cycle trajectory. The three local basins of attraction characterize the G1, S/G2, and M phases. The barriers characterize the G1 and S/G2 checkpoints, respectively, of the cell cycle, thus providing an explanation of the checkpoint mechanism for the cell cycle from the physical perspective. We found that the progression of a cell cycle is determined by two driving forces: curl flux for acceleration and potential barriers for deceleration along the cycle path. Therefore, the cell cycle can be promoted (suppressed), either by enhancing (suppressing) the flux (representing the energy input) or by lowering (increasing) the barrier along the cell cycle path. We found that both the entropy production rate and energy per cell cycle increase as the growth factor increases. This reflects that cell growth and division are driven by energy or nutrition supply. More energy input increases flux and decreases barrier along the cell cycle path, leading to faster oscillations. We also identified certain key genes and regulations for stability and progression of the cell cycle. Some of these findings were evidenced from experiments whereas others lead to predictions and potential anticancer strategies. PMID:25228772

Identification of Cell Cycle-Regulated Genes by Convolutional Neural Network.

PubMed

Liu, Chenglin; Cui, Peng; Huang, Tao

2017-01-01

The cell cycle-regulated genes express periodically with the cell cycle stages, and the identification and study of these genes can provide a deep understanding of the cell cycle process. Large false positives and low overlaps are big problems in cell cycle-regulated gene detection. Here, a computational framework called DLGene was proposed for cell cycle-regulated gene detection. It is based on the convolutional neural network, a deep learning algorithm representing raw form of data pattern without assumption of their distribution. First, the expression data was transformed to categorical state data to denote the changing state of gene expression, and four different expression patterns were revealed for the reported cell cycle-regulated genes. Then, DLGene was applied to discriminate the non-cell cycle gene and the four subtypes of cell cycle genes. Its performances were compared with six traditional machine learning methods. At last, the biological functions of representative cell cycle genes for each subtype are analyzed. Our method showed better and more balanced performance of sensitivity and specificity comparing to other machine learning algorithms. The cell cycle genes had very different expression pattern with non-cell cycle genes and among the cell-cycle genes, there were four subtypes. Our method not only detects the cell cycle genes, but also describes its expression pattern, such as when its highest expression level is reached and how it changes with time. For each type, we analyzed the biological functions of the representative genes and such results provided novel insight to the cell cycle mechanisms. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Antimetabolic Effects of Polyphenols in Breast Cancer Cells: Focus on Glucose Uptake and Metabolism.

PubMed

Keating, Elisa; Martel, Fátima

2018-01-01

In the last years, metabolic reprogramming became a new key hallmark of tumor cells. One of its components is a deviant energetic metabolism, known as Warburg effect-an aerobic lactatogenesis- characterized by elevated rates of glucose uptake and consumption with high-lactate production even in the presence of oxygen. Because many cancer cells display a greater sensitivity to glucose deprivation-induced cytotoxicity than normal cells, inhibitors of glucose cellular uptake (facilitative glucose transporter 1 inhibitors) and oxidative metabolism (glycolysis inhibitors) are potential therapeutic targets in cancer treatment. Polyphenols, abundantly contained in fruits and vegetables, are dietary components with an established protective role against cancer. Several molecular mechanisms are involved in the anticancer effect of polyphenols, including effects on apoptosis, cell cycle regulation, plasma membrane receptors, signaling pathways, and epigenetic mechanisms. Additionally, inhibition of glucose cellular uptake and metabolism in cancer cell lines has been described for several polyphenols, and this effect was shown to be associated with their anticarcinogenic effect. This work will review data showing an antimetabolic effect of polyphenols and its involvement in the chemopreventive/chemotherapeutic potential of these dietary compounds, in relation to breast cancer.

Technology for Bayton-cycle powerplants using solar and nuclear energy

NASA Technical Reports Server (NTRS)

English, R. E.

1986-01-01

Brayton cycle gas turbines have the potential to use either solar heat or nuclear reactors for generating from tens of kilowatts to tens of megawatts of power in space, all this from a single technology for the power generating system. Their development for solar energy dynamic power generation for the space station could be the first step in an evolution of such powerplants for a very wide range of applications. At the low power level of only 10 kWe, a power generating system has already demonstrated overall efficiency of 0.29 and operated 38 000 hr. Tests of improved components show that these components would raise that efficiency to 0.32, a value twice that demonstrated by any alternate concept. Because of this high efficiency, solar Brayton cycle power generators offer the potential to increase power per unit of solar collector area to levels exceeding four times that from photovoltaic powerplants using present technology for silicon solar cells. The technologies for solar mirrors and heat receivers are reviewed and assessed. This Brayton technology for solar powerplants is equally suitable for use with the nuclear reactors. The available long time creep data on the tantalum alloy ASTAR-811C show that such Brayton cycles can evolve to cycle peak temperatures of 1500 K (2240 F). And this same technology can be extended to generate 10 to 100 MW in space by exploiting existing technology for terrestrial gas turbines in the fields of both aircraft propulsion and stationary power generation.

Cell cycle phases in the unequal mother/daughter cell cycles of Saccharomyces cerevisiae.

PubMed

Brewer, B J; Chlebowicz-Sledziewska, E; Fangman, W L

1984-11-01

During cell division in the yeast Saccharomyces cerevisiae mother cells produce buds (daughter cells) which are smaller and have longer cell cycles. We performed experiments to compare the lengths of cell cycle phases in mothers and daughters. As anticipated from earlier indirect observations, the longer cell cycle time of daughter cells is accounted for by a longer G1 interval. The S-phase and the G2-phase are of the same duration in mother and daughter cells. An analysis of five isogenic strains shows that cell cycle phase lengths are independent of cell ploidy and mating type.

Progress towards computer simulation of NiH2 battery performance over life

NASA Technical Reports Server (NTRS)

Zimmerman, Albert H.; Quinzio, M. V.

1995-01-01

The long-term performance of rechargeable battery cells has traditionally been verified through life-testing, a procedure that generally requires significant commitments of funding and test resources. In the situation of nickel hydrogen battery cells, which have the capability of providing extremely long cycle life, the time and cost required to conduct even accelerated testing has become a serious impediment to transitioning technology improvements into spacecraft applications. The utilization of computer simulations to indicate the changes in performance to be expected in response to design or operating changes in nickel hydrogen cells is therefore a particularly attractive tool in advanced battery development, as well as for verifying performance in different applications. Computer-based simulations of the long-term performance of rechargeable battery cells have typically had very limited success in the past. There are a number of reasons for the lack in progress in this area. First, and probably most important, all battery cells are relatively complex electrochemical systems, in which performance is dictated by a large number of interacting physical and chemical processes. While the complexity alone is a significant part of the problem, in many instances the fundamental chemical and physical processes underlying long-term degradation and its effects on performance have not even been understood. Second, while specific chemical and physical changes within cell components have been associated with degradation, there has been no generalized simulation architecture that enables the chemical and physical structure (and changes therein) to be translated into cell performance. For the nickel hydrogen battery cell, our knowledge of the underlying reactions that control the performance of this cell has progressed to where it clearly is possible to model them. The recent development of a relative generalized cell modelling approach provides the framework for translating the chemical and physical structure of the components inside a cell into its performance characteristics over its entire cycle life. This report describes our approach to this task in terms of defining those processes deemed critical in controlling performance over life, and the model architecture required to translate the fundamental cell processes into performance profiles.

Stromal interaction molecule 1 (STIM1) silencing inhibits tumor growth and promotes cell cycle arrest and apoptosis in hypopharyngeal carcinoma.

PubMed

Sun, Yuanhao; Cui, Xiaobo; Wang, Jun; Wu, Shuai; Bai, Yunfei; Wang, Yaping; Wang, Boqian; Fang, Jugao

2015-05-01

As an important pathway maintaining the balance of intracellular calcium (Ca(2+)), store-operated Ca(2+) entry (SOCE) is critical for cellular functions. Stromal interaction molecule 1 (STIM1), a key component of SOCE, plays a dual role as an endoplasmic reticulum Ca(2+) receptor and an SOCE exciter. Aberrant expression of STIM1 could be discovered in several human cancer cells. However, the role of STIM1 in regulating human hypopharyngeal carcinoma still remains unclear. Real-time polymerase chain reaction (PCR) was used to detect expression of STIM1 in human hypopharyngeal carcinoma cell line FaDu. STIM1 on FaDu cells was knocked down by lentiviral transduction method. The biological impacts after knocking down of STIM1 on FaDu cells were investigated in vitro and in vivo. The result of real-time PCR showed that STIM1 was expressed in FaDu cells. Lentiviral transduction efficiently downregulated the expression of STIM1 in FaDu cells at both mRNA and protein levels. Significant downregulation of STIM1 on FaDu cells inhibited cell proliferation, induced cell cycle arrest in G0/G1 phase, promoted cell apoptosis, and restrained cell growth rate. The antigrowth effect of STIM1 silencing was also discovered in FaDu hypopharyngeal tumor model. Our findings indicate that STIM1 is likely to become a new therapeutic target for hypopharyngeal carcinoma treatment.

The Global Regulatory Architecture of Transcription during the Caulobacter Cell Cycle

PubMed Central

Zhou, Bo; Schrader, Jared M.; Kalogeraki, Virginia S.; Abeliuk, Eduardo; Dinh, Cong B.; Pham, James Q.; Cui, Zhongying Z.; Dill, David L.; McAdams, Harley H.; Shapiro, Lucy

2015-01-01

Each Caulobacter cell cycle involves differentiation and an asymmetric cell division driven by a cyclical regulatory circuit comprised of four transcription factors (TFs) and a DNA methyltransferase. Using a modified global 5′ RACE protocol, we globally mapped transcription start sites (TSSs) at base-pair resolution, measured their transcription levels at multiple times in the cell cycle, and identified their transcription factor binding sites. Out of 2726 TSSs, 586 were shown to be cell cycle-regulated and we identified 529 binding sites for the cell cycle master regulators. Twenty-three percent of the cell cycle-regulated promoters were found to be under the combinatorial control of two or more of the global regulators. Previously unknown features of the core cell cycle circuit were identified, including 107 antisense TSSs which exhibit cell cycle-control, and 241 genes with multiple TSSs whose transcription levels often exhibited different cell cycle timing. Cumulatively, this study uncovered novel new layers of transcriptional regulation mediating the bacterial cell cycle. PMID:25569173

Indirect-fired gas turbine dual fuel cell power cycle

DOEpatents

Micheli, Paul L.; Williams, Mark C.; Sudhoff, Frederick A.

1996-01-01

A fuel cell and gas turbine combined cycle system which includes dual fuel cell cycles combined with a gas turbine cycle wherein a solid oxide fuel cell cycle operated at a pressure of between 6 to 15 atms tops the turbine cycle and is used to produce CO.sub.2 for a molten carbonate fuel cell cycle which bottoms the turbine and is operated at essentially atmospheric pressure. A high pressure combustor is used to combust the excess fuel from the topping fuel cell cycle to further heat the pressurized gas driving the turbine. A low pressure combustor is used to combust the excess fuel from the bottoming fuel cell to reheat the gas stream passing out of the turbine which is used to preheat the pressurized air stream entering the topping fuel cell before passing into the bottoming fuel cell cathode. The CO.sub.2 generated in the solid oxide fuel cell cycle cascades through the system to the molten carbonate fuel cell cycle cathode.

The global regulatory architecture of transcription during the Caulobacter cell cycle.

PubMed

Zhou, Bo; Schrader, Jared M; Kalogeraki, Virginia S; Abeliuk, Eduardo; Dinh, Cong B; Pham, James Q; Cui, Zhongying Z; Dill, David L; McAdams, Harley H; Shapiro, Lucy

2015-01-01

Each Caulobacter cell cycle involves differentiation and an asymmetric cell division driven by a cyclical regulatory circuit comprised of four transcription factors (TFs) and a DNA methyltransferase. Using a modified global 5' RACE protocol, we globally mapped transcription start sites (TSSs) at base-pair resolution, measured their transcription levels at multiple times in the cell cycle, and identified their transcription factor binding sites. Out of 2726 TSSs, 586 were shown to be cell cycle-regulated and we identified 529 binding sites for the cell cycle master regulators. Twenty-three percent of the cell cycle-regulated promoters were found to be under the combinatorial control of two or more of the global regulators. Previously unknown features of the core cell cycle circuit were identified, including 107 antisense TSSs which exhibit cell cycle-control, and 241 genes with multiple TSSs whose transcription levels often exhibited different cell cycle timing. Cumulatively, this study uncovered novel new layers of transcriptional regulation mediating the bacterial cell cycle.

Withaferin A activates stress signalling proteins in high risk acute lymphoblastic leukemia

PubMed Central

Shi, Li-Huan; Wu, Xi-Jun; Liu, Jun-Shan; Gao, Yin-Bo

2015-01-01

Withaferin A, the principal bio-active component isolated from the Withaniasomnifera, has shown promising anti-leukemic activity in addition to anti-invasive and anti-metastatic activity. The present study demonstrates the effect of withaferin A on the cell cycle status and the phosphorylation/activation of proteins involved in signal transduction in t(4;11) and non-t(4;11) acute lymphoblastic leukemia (ALL) cell lines after treatment with withaferin A. The cells after treatment with the vehicle or 25 μM withaferin A for 1, 2, 4 and 8 h were examined using flow cytometric analysis. The results revealed that withaferin A treatment induced cell growth arrest at the S to G2/M phase transition of the cell cycle. Withaferin A treatment also induced the phosphorylation of stress signalling proteins, including the p38 mitogen-activated protein kinase, the c-Jun N-terminal kinase, c-Jun, the heat shock protein 27 and protein kinase B within 0 to 16 h. These results were observed using multiplex technology and Western blotting analysis. Thus withaferin A induces stress response leading to cell death. Therefore, withaferin A can be a potent therapeutic agent for the treatment of high risk ALL with chromosomal translocation t(4;11). PMID:26884834

Withaferin A activates stress signalling proteins in high risk acute lymphoblastic leukemia.

PubMed

Shi, Li-Huan; Wu, Xi-Jun; Liu, Jun-Shan; Gao, Yin-Bo

2015-01-01

Withaferin A, the principal bio-active component isolated from the Withaniasomnifera, has shown promising anti-leukemic activity in addition to anti-invasive and anti-metastatic activity. The present study demonstrates the effect of withaferin A on the cell cycle status and the phosphorylation/activation of proteins involved in signal transduction in t(4;11) and non-t(4;11) acute lymphoblastic leukemia (ALL) cell lines after treatment with withaferin A. The cells after treatment with the vehicle or 25 μM withaferin A for 1, 2, 4 and 8 h were examined using flow cytometric analysis. The results revealed that withaferin A treatment induced cell growth arrest at the S to G2/M phase transition of the cell cycle. Withaferin A treatment also induced the phosphorylation of stress signalling proteins, including the p38 mitogen-activated protein kinase, the c-Jun N-terminal kinase, c-Jun, the heat shock protein 27 and protein kinase B within 0 to 16 h. These results were observed using multiplex technology and Western blotting analysis. Thus withaferin A induces stress response leading to cell death. Therefore, withaferin A can be a potent therapeutic agent for the treatment of high risk ALL with chromosomal translocation t(4;11).

Antitumor Activity of Ethanolic Extract of Dendrobium formosum in T-Cell Lymphoma: An In Vitro and In Vivo Study

PubMed Central

Prasad, Ritika; Koch, Biplob

2014-01-01

Dendrobium, a genus of orchid, was found to possess useful therapeutic activities like anticancer, hypoglycaemic, antimicrobial, immunomodulatory, hepatoprotective, antioxidant, and neuroprotective activities. The study was aimed to evaluate the anticancer property of the ethanolic extract of Dendrobium formosum on Dalton's lymphoma. In vitro cytotoxicity was determined by MTT assay, apoptosis was determined by fluorescence microscopy, and cell cycle progression was analysed using flow cytometry; in vivo antitumor activity was performed in Dalton's lymphoma bearing mice. The IC50 value of ethanolic extract was obtained at 350 μg/mL in Dalton's lymphoma cells. Fluorescence microscopy analysis showed significant increase in apoptotic cell death in dose- and time-dependent manner which was further confirmed through the resulting DNA fragmentation. Further, flow cytometry analysis showed that the ethanolic extract arrests the cells in G2/M phase of the cell cycle. The in vivo anticancer activity study illustrates significant increase in the survival time of Dalton's lymphoma bearing mice on treatment with ethanolic extract when compared to control. These results substantiate the antitumor properties of ethanolic extract of Dendrobium formosum and suggest an alternative in treatment of cancer. Further studies are required regarding the isolation and characterization of bioactive components along with the analysis of molecular mechanism involved. PMID:24959588

The cell cycle as a brake for β-cell regeneration from embryonic stem cells.

PubMed

El-Badawy, Ahmed; El-Badri, Nagwa

2016-01-13

The generation of insulin-producing β cells from stem cells in vitro provides a promising source of cells for cell transplantation therapy in diabetes. However, insulin-producing cells generated from human stem cells show deficiency in many functional characteristics compared with pancreatic β cells. Recent reports have shown molecular ties between the cell cycle and the differentiation mechanism of embryonic stem (ES) cells, assuming that cell fate decisions are controlled by the cell cycle machinery. Both β cells and ES cells possess unique cell cycle machinery yet with significant contrasts. In this review, we compare the cell cycle control mechanisms in both ES cells and β cells, and highlight the fundamental differences between pluripotent cells of embryonic origin and differentiated β cells. Through critical analysis of the differences of the cell cycle between these two cell types, we propose that the cell cycle of ES cells may act as a brake for β-cell regeneration. Based on these differences, we discuss the potential of modulating the cell cycle of ES cells for the large-scale generation of functionally mature β cells in vitro. Further understanding of the factors that modulate the ES cell cycle will lead to new approaches to enhance the production of functional mature insulin-producing cells, and yield a reliable system to generate bona fide β cells in vitro.

TGF-beta3 is expressed in taste buds and inhibits proliferation of primary cultured taste epithelial cells.

PubMed

Nakamura, Shin-ichi; Kawai, Takayuki; Kamakura, Takashi; Ookura, Tetsuya

2010-01-01

Transforming growth factor-betas (TGF-betas), expressed in various tissues, play important roles in embryonic development and adult tissue homeostasis through their effects on cell proliferation, cell differentiation, cell death, and cell motility. However, expression of TGF-beta signaling components and their biological effect on taste epithelia has not been elucidated. We performed expression analysis of TGF-beta signaling components in taste epithelia and found that the TGF-beta3 mRNA was specifically expressed in taste buds. Type II TGF-betas receptor (TbetaR-II) mRNA was specifically expressed in the tongue epithelia including the taste epithelia. To elucidate the biological function of TGF-beta3 in taste epithelia, we performed proliferation assay with primary cultured taste epithelial cells. In the presence of TGF-beta3, percentage of BrdU-labeled cells decreased significantly, suggesting that the TGF-beta3 inhibited the proliferation of cultured taste epithelial cells through inhibiting cell-cycle entry into S phase. By quantitative reverse transcription-polymerase chain reaction assay, we found that the TGF-beta3 resulted in an increased level of expression of p15Ink4b and p21Cip1, suggesting that the TGF-beta3 inhibited the taste epithelial cell proliferation through inhibiting G1cyclin-Cdk complexes. Taken together, these results suggested that the TGF-beta3 may regulate taste epithelial cell homeostasis through controlling cell proliferation.

Analysis on the Alpinia katsumadai components of Zingiberaceae plants and their functions on myeloma resistance.

PubMed

Wang, Jue; Qiu, Rubiao; Yuan, Lianjing; Meng, Fei; Tang, Qian

2015-05-01

Generally speaking, zingiberaceae plants with sweet fragrance are commonly seen as perennial herbs that contains numerous well-known crude drugs and fragrant plants like Amomum villosum, Amomumtsao-ko, Ginger, Alpinia katsumadai and Radix curcumae, which are widely used in daily life. This paper analyzed chemical components of Alpinia katsumadai of zingiberaceae and applied several laminar analysis to further develop its active ingredients, aiming to make sure its function on tumor assistance. Actually, cardamomin contained in Alpinia katsumadai has been recorded to act notably in myeloma resistance, which was verified by cholecystokinin-octopeptide (CCK-8) in this paper. Cardamom in is proved to have multiple anti-myeloma effects, including myeloma cell activity and proliferation control, cell cycle retardant and apoptosis induction, which indicates its value in the field of medical pharmacy.

GSFLOW - Coupled Ground-Water and Surface-Water Flow Model Based on the Integration of the Precipitation-Runoff Modeling System (PRMS) and the Modular Ground-Water Flow Model (MODFLOW-2005)

USGS Publications Warehouse

Markstrom, Steven L.; Niswonger, Richard G.; Regan, R. Steven; Prudic, David E.; Barlow, Paul M.

2008-01-01

The need to assess the effects of variability in climate, biota, geology, and human activities on water availability and flow requires the development of models that couple two or more components of the hydrologic cycle. An integrated hydrologic model called GSFLOW (Ground-water and Surface-water FLOW) was developed to simulate coupled ground-water and surface-water resources. The new model is based on the integration of the U.S. Geological Survey Precipitation-Runoff Modeling System (PRMS) and the U.S. Geological Survey Modular Ground-Water Flow Model (MODFLOW). Additional model components were developed, and existing components were modified, to facilitate integration of the models. Methods were developed to route flow among the PRMS Hydrologic Response Units (HRUs) and between the HRUs and the MODFLOW finite-difference cells. This report describes the organization, concepts, design, and mathematical formulation of all GSFLOW model components. An important aspect of the integrated model design is its ability to conserve water mass and to provide comprehensive water budgets for a location of interest. This report includes descriptions of how water budgets are calculated for the integrated model and for individual model components. GSFLOW provides a robust modeling system for simulating flow through the hydrologic cycle, while allowing for future enhancements to incorporate other simulation techniques.

Comparative cell cycle transcriptomics reveals synchronization of developmental transcription factor networks in cancer cells

PubMed Central

Johard, Helena; Mahdessian, Diana; Fedr, Radek; Marks, Carolyn; Medalová, Jiřina; Souček, Karel; Lundberg, Emma; Linnarsson, Sten; Bryja, Vítězslav; Sekyrova, Petra; Altun, Mikael; Andäng, Michael

2017-01-01

The cell cycle coordinates core functions such as replication and cell division. However, cell-cycle-regulated transcription in the control of non-core functions, such as cell identity maintenance through specific transcription factors (TFs) and signalling pathways remains unclear. Here, we provide a resource consisting of mapped transcriptomes in unsynchronized HeLa and U2OS cancer cells sorted for cell cycle phase by Fucci reporter expression. We developed a novel algorithm for data analysis that enables efficient visualization and data comparisons and identified cell cycle synchronization of Notch signalling and TFs associated with development. Furthermore, the cell cycle synchronizes with the circadian clock, providing a possible link between developmental transcriptional networks and the cell cycle. In conclusion we find that cell cycle synchronized transcriptional patterns are temporally compartmentalized and more complex than previously anticipated, involving genes, which control cell identity and development. PMID:29228002

Simulated Carbon Cycling in a Model Microbial Mat.

NASA Astrophysics Data System (ADS)

Decker, K. L.; Potter, C. S.

2006-12-01

We present here the novel addition of detailed organic carbon cycling to our model of a hypersaline microbial mat ecosystem. This ecosystem model, MBGC (Microbial BioGeoChemistry), simulates carbon fixation through oxygenic and anoxygenic photosynthesis, and the release of C and electrons for microbial heterotrophs via cyanobacterial exudates and also via a pool of dead cells. Previously in MBGC, the organic portion of the carbon cycle was simplified into a black-box rate of accumulation of simple and complex organic compounds based on photosynthesis and mortality rates. We will discuss the novel inclusion of fermentation as a source of carbon and electrons for use in methanogenesis and sulfate reduction, and the influence of photorespiration on labile carbon exudation rates in cyanobacteria. We will also discuss the modeling of decomposition of dead cells and the ultimate release of inorganic carbon. The detailed modeling of organic carbon cycling is important to the accurate representation of inorganic carbon flux through the mat, as well as to accurate representation of growth models of the heterotrophs under different environmental conditions. Because the model ecosystem is an analog of ancient microbial mats that had huge impacts on the atmosphere of early earth, this MBGC can be useful as a biological component to either early earth models or models of other planets that potentially harbor life.

Homeostasis 5: nurses as external agents of control in breast cancer.

PubMed

Clancy, John; McVicar, Andrew

Breast cancer is caused by a homeostatic imbalance of cell division. Healthcare practitioners need to understand cellular activities to appreciate the physiological basis of health (homeostasis), the pathophysiological basis of illness and the physiological rationale of healthcare. Cells are the 'basic unit of life' (Clancy and McVicar, 2011a). This article describes normal cell division and the anatomy and physiology of the breast and, using a case study, will show how breast cancer is a homeostatic imbalance of cell division. There are analogies between the components of homeostasis and the components of the nursing (healthcare) process (Clancy and McVicar, 2011b) in the condition of breast cancer. After reading this article, nurses should be able to: understand that breast cancer is a cellular hence chemical imbalance that causes uncontrollable mitotic division of breast cells; understand how the cell cycle of cancer cells differs from that of normal cells; identify nature-nurture interactions involved in the aetiology of breast cancer; understand that when caring for people with breast cancer, health professionals including oncology nurses are acting as external agents of homeostatic control as the patient 'recovers' from breast cancer, and also to some extent when reducing signs and symptoms, hence quality of life, by providing palliative care.

Effect of KOH concentration on LEO cycle life of IPV nickel-hydrogen flight cell - Update II

NASA Technical Reports Server (NTRS)

Smithrick, John J.; Hall, Stephen W.

1992-01-01

An update of validation test results confirming the breakthrough in LEO cycle life of nickel-hydrogen cells containing 26 percent KOH electrolyte is presented. A breakthrough in the LEO cycle life of individual pressure vessel (IPV) nickel-hydrogen cells has been previously reported. The cycle life of boiler plate cells containing 26 percent potassium hydroxide (KOH) electrolyte was about 40,000 LEO cycles, compared to 3500 cycles for cells containing 31 percent KOH. The cycle regime was a stressful accelerated LEO, which consisted of a 27.5 min charge followed by a 17.5 min discharge (2X normal rate). The depth-of-discharge was 80 percent. Six 48-Ah Hughes recirculation design IPV nickel-hydrogen flight battery cells are being evaluated. Three of the cells contain 26 percent KOH (test cells), and three contain 31 percent KOH (control cells). They are undergoing real time LEO cycle life testing. The cycle regime is a 90-min LEO orbit consisting of a 54-min charge followed by a 36-min discharge. The depth-of-discharge is 80 percent. The cell temperature is maintained at 10 C. The three 31 percent KOH cells failed (cycles 3729, 4165, and 11355). One of the 26 percent KOH cells failed at cycle 15314. The other two 26 percent KOH cells were cycled for over 16,000 cycles during the continuing test.

6-Gingerol inhibits osteosarcoma cell proliferation through apoptosis and AMPK activation.

PubMed

Fan, Jingzhang; Yang, Xin; Bi, Zhenggang

2015-02-01

6-Gingerol, a major component of ginger, is demonstrated to possess a variety of pharmacological activities. Despite demonstration of its anti-cancer activity, the exact mechanism underlying the effects of 6-gingerol against sarcoma remains sketchy. In the present study, we investigated the anti-cancer effects of 6-gingerol on osteosarcoma cells. MTT assay was performed to determine cell viability. Phosphorylation and protein levels were determined by immunoblotting. Cell cycle was determined using flow cytometry. Quantitative polymerase chain reaction was employed to determine the changes in the messenger RNA (mRNA) expression of genes. Treatment with 6-gingerol resulted in a significant decrease in the viability of osteosarcoma cells in a dose-dependent fashion. In parallel, the number of cells arrested at the sub-G1 cell cycle phase was significantly increased. The results showed that 6-gingerol induced activation of caspase cascades and regulated cellular levels of Bcl2 and Bax. Moreover, 6-gingerol activated AMP-activated protein kinase (AMPK) signaling associated with the apoptotic pathways. Our findings suggest that 6-gingerol suppresses the growth of osteosarcoma cells. The anti-cancer activity is attributed to the activation of apoptotic signaling and the inhibition of anti-apoptotic signaling incorporating with 6-gingerol-induced AMPK activation. The study identifies a new molecular mechanism by which AMPK is involved in anti-cancer effects of 6-gingerol.

2',4'-Dihydroxychalcone-induced apoptosis of human gastric cancer MGC-803 cells via down-regulation of survivin mRNA.

PubMed

Lou, Chenghua; Yang, Guangming; Cai, Hao; Zou, Mingchang; Xu, Zisheng; Li, Yu; Zhao, Fengming; Li, Weidong; Tong, Li; Wang, Mingyan; Cai, Baochang

2010-08-01

2',4'-Dihydroxychalcone (TFC), a main component in Herba Oxytropis, is grouped under flavonoids, which are well known to have antitumor activities in vitro. In this study, the possible antitumor mechanism of TFC in human gastric cancer MGC-803 cells is examined. Hoechst 33258 staining analysis indicates that TFC causes MGC-803 cell shrinkage and apoptotic body formation, typical characteristics of apoptosis. Flow cytometric analysis demonstrates that TFC causes cell cycle arrest in the G2/M phase. Furthermore, TFC significantly increases caspase-3 activity but decreases survivin mRNA expression. Therefore, TFC can induce the apoptosis of MGC-803 cells via down-regulation of survivin mRNA expression. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Novel Derivative of Benzofuran Induces Cell Death Mostly by G2/M Cell Cycle Arrest through p53-dependent Pathway but Partially by Inhibition of NF-κB*

PubMed Central

Manna, Sunil K.; Bose, Julie S.; Gangan, Vijay; Raviprakash, Nune; Navaneetha, Thota; Raghavendra, Pongali B.; Babajan, Banaganapalli; Kumar, Chitta S.; Jain, Swatantra K.

2010-01-01

The Dracaena resin is widely used in traditional medicine as an anticancer agent, and benzofuran lignan is the active component. In this report, we provide evidence that the synthetic derivative of benzofuran lignan (Benfur) showed antitumor activities. It induced apoptosis in p53-positive cells. Though it inhibited endotoxin-induced nuclear factor κB (NF-κB) activation in both p53-positive and -negative cells, the activation of caspase 3 was observed in p53-positive cells. It showed partial cell death effect in both p53-positive and -negative cells through inhibition of NF-κB. Cell cycle analysis using flow cytometry showed that treatment with this novel benozofuran lignan derivative to Jurkat T-cells, but not U-937 cells, resulted in a G2/M arrest in a dose- and time-dependent manner. It increased amounts of p21, p27, and cyclin B, but not phospho-Rb through p53 nuclear translocation in Jurkat T-cells, but not in U-937 cells. It inhibited amounts of MDM2 (murine double minute 2) by repressing the transcription factor Sp1, which was also proved in silico. It induced cell death in tumor cells, but not in primary T-cells. Overall, our data suggest that Benfur-mediated cell death is partially dependent upon NF-κB, but predominantly dependent on p53. Thus, this novel benzofuran lignan derivative can be effective chemopreventive or chemotherapeutic agent against malignant T-cells. PMID:20472557

Gigantism in a Bacterium, Epulopiscium fishelsoni, Correlates with Complex Patterns in Arrangement, Quantity, and Segregation of DNA

PubMed Central

Bresler, V.; Montgomery, W. L.; Fishelson, L.; Pollak, P. E.

1998-01-01

Epulopiscium fishelsoni, gut symbiont of the brown surgeonfish (Acanthurus nigrofuscus) in the Red Sea, attains a larger size than any other eubacterium, varies 10- to 20-fold in length (and >2,000-fold in volume), and undergoes a complex daily life cycle. In early morning, nucleoids contain highly condensed DNA in elongate, chromosome-like structures which are physically separated from the general cytoplasm. Cell division involves production of two (rarely three) nucleoids within a cell, deposition of cell walls around expanded nucleoids, and emergence of daughter cells from the parent cell. Fluorescence measurements of DNA, RNA, and other cell components indicate the following. DNA quantity is proportional to cell volume over cell lengths of ∼30 μm to >500 μm. For cells of a given size, nucleoids of cells with two nucleoids (binucleoid) contain approximately equal amounts of DNA. And each nucleoid of a binucleoid cell contains one-half the DNA of the single nucleoid in a uninucleoid cell of the same size. The life cycle involves approximately equal subdivision of DNA among daughter cells, formation of apical caps of condensed DNA from previously decondensed and diffusely distributed DNA, and “pinching” of DNA near the middle of the cell in the absence of new wall formation. Mechanisms underlying these patterns remain unclear, but formation of daughter nucleoids and cells occurs both during diurnal periods of host feeding and bacterial cell growth and during nocturnal periods of host inactivity when mean bacterial cell size declines. PMID:9791108

The cell cycle.

PubMed

Singh, N; Lim, R B; Sawyer, M A

2000-07-01

The cell cycle and the cell cycle control system are the engines that drive life. They allow for the processes of cell renewal and the growth of organisms, under controlled conditions. The control system is essential for the monitoring of normal cell growth and replication of genetic material and to ensure that normal, functional daughter cells are produced at completion of each cell cycle. Although certain clinical applications exist which take advantage of the events of the cell cycle, our understanding of its mechanisms and how to manipulate them is infantile. The next decades will continue to see the effort of many researchers focused upon unlocking the mysteries of the cell cycle and the cell cycle control system.

Pathological implications of cell cycle re-entry in Alzheimer disease.

PubMed

Bonda, David J; Lee, Hyun-pil; Kudo, Wataru; Zhu, Xiongwei; Smith, Mark A; Lee, Hyoung-gon

2010-06-29

The complex neurodegeneration underlying Alzheimer disease (AD), although incompletely understood, is characterised by an aberrant re-entry into the cell cycle in neurons. Pathological evidence, in the form of cell cycle markers and regulatory proteins, suggests that cell cycle re-entry is an early event in AD, which precedes the formation of amyloid-beta plaques and neurofibrillary tangles (NFTs). Although the exact mechanisms that induce and mediate these cell cycle events in AD are not clear, significant advances have been made in further understanding the pathological role of cell cycle re-entry in AD. Importantly, recent studies indicate that cell cycle re-entry is not a consequence, but rather a cause, of neurodegeneration, suggesting that targeting of cell cycle re-entry may provide an opportunity for therapeutic intervention. Moreover, multiple inducers of cell cycle re-entry and their interactions in AD have been proposed. Here, we review the most recent advances in understanding the pathological implications of cell cycle re-entry in AD.

Supercapacitors based on 3D network of activated carbon nanowhiskers wrapped-on graphitized electrospun nanofibers

NASA Astrophysics Data System (ADS)

He, Shuijian; Chen, Linlin; Xie, Chencheng; Hu, Huan; Chen, Shuiliang; Hanif, Muddasir; Hou, Haoqing

2013-12-01

Due to their cycling stability and high power density, the supercapacitors bridge the power/energy gap between traditional dielectric capacitors and batteries/fuel cells. Electrode materials are key components for making high performance supercapacitors. An activated carbon nanowhiskers (ACNWs) wrapped-on graphitized electrospun nanofiber (GENF) network (ACNWs/GENFN) with 3D porous structure is prepared as a new type of binder-free electrode material for supercapacitors. The supercapacitor based on the ACNWs/GENFN composite material displays an excellent performance with a specific capacitance of 176.5 F g-1 at current density of 0.5 A g-1, an ultrahigh power density of 252.8 kW kg-1 at current density of 800 A g-1 and an outstanding cycling stability of no capacitance loss after 10,000 charge/discharge cycles.

Biodynamic study of americium-241 accumulation in the cytosol of the hepatopancreas of the lobster Homarus gammarus.

PubMed

Goudard, F; Paquet, F; Durand, J P; Milcent, M C; Germain, P; Pieri, J

1994-08-01

In the lobster, most of the radionuclides ingested with contaminated food are concentrated in the digestive gland. Americium-241 accumulation in the hepatopancreas of the lobster was studied during the digestive cycle. Fractionations of cytosols at different times after ingestion of radioactive preys were performed by gel permeation chromatography to determine the distribution of 241Am in the different macromolecular components. 241Am was associated with ferritin during the whole digestive cycle. This observation suggests a correlation between 241Am distribution pathways and iron metabolism. The distribution of 241Am present in the other cytosolic proteins followed two major steps of accumulation which may be correlated to the evolution of the two main cellular types playing an important role in the digestive cycle (B and R type cells).

Electrochemical activity of Fe-MIL-100 as a positive electrode for Na-ion batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sava Gallis, Dorina F.; Pratt III, Harry D.; Anderson, Travis M.

2016-01-01

Here we investigate the electrochemical activity of metal-organic frameworks (MOFs) as positive electrodes for Na-ion batteries in coin cell configurations. The performance of Fe-MIL-100 material is highly dependent on the choice of sodium salt source, and electrolyte system. The overall capacity fades over many cycles, however the high Coulombic efficiency is maintained. This can be correlated with inaccessibility of active sites for Na intercalation, due to the increase of extra carbonaceous material inside the pores. High resolution synchrotron powder X-ray and pair distribution function analyses of the as-made and cycled electrodes reveal the structure maintains the long-range order with progressivemore » cycling. This finding suggests that careful consideration of all variables in battery components, and especially electrolyte selection can lead to greatly improved performances.« less

Cell-cycle synchronisation of bloodstream forms of Trypanosoma brucei using Vybrant DyeCycle Violet-based sorting.

PubMed

Kabani, Sarah; Waterfall, Martin; Matthews, Keith R

2010-01-01

Studies on the cell-cycle of Trypanosoma brucei have revealed several unusual characteristics that differ from the model eukaryotic organisms. However, the inability to isolate homogenous populations of parasites in distinct cell-cycle stages has limited the analysis of trypanosome cell division and complicated the understanding of mutant phenotypes with possible impact on cell-cycle related events. Although hydroxyurea-induced cell-cycle arrest in procyclic and bloodstream forms has been applied recently with success, such block-release protocols can complicate the analysis of cell-cycle regulated events and have the potential to disrupt important cell-cycle checkpoints. An alternative approach based on flow cytometry of parasites stained with Vybrant DyeCycle Orange circumvents this problem, but is restricted to procyclic form parasites. Here, we apply Vybrant Dyecycle Violet staining coupled with flow cytometry to effectively select different cell-cycle stages of bloodstream form trypanosomes. Moreover, the sorted parasites remain viable, although synchrony is rapidly lost. This method enables cell-cycle enrichment of populations of trypanosomes in their mammal infective stage, particularly at the G1 phase.

Cell-cycle synchronisation of bloodstream forms of Trypanosoma brucei using Vybrant DyeCycle Violet-based sorting

PubMed Central

Kabani, Sarah; Waterfall, Martin; Matthews, Keith R.

2010-01-01

Studies on the cell-cycle of Trypanosoma brucei have revealed several unusual characteristics that differ from the model eukaryotic organisms. However, the inability to isolate homogenous populations of parasites in distinct cell-cycle stages has limited the analysis of trypanosome cell division and complicated the understanding of mutant phenotypes with possible impact on cell-cycle related events. Although hydroxyurea-induced cell-cycle arrest in procyclic and bloodstream forms has been applied recently with success, such block-release protocols can complicate the analysis of cell-cycle regulated events and have the potential to disrupt important cell-cycle checkpoints. An alternative approach based on flow cytometry of parasites stained with Vybrant DyeCycle Orange circumvents this problem, but is restricted to procyclic form parasites. Here, we apply Vybrant Dyecycle Violet staining coupled with flow cytometry to effectively select different cell-cycle stages of bloodstream form trypanosomes. Moreover, the sorted parasites remain viable, although synchrony is rapidly lost. This method enables cell-cycle enrichment of populations of trypanosomes in their mammal infective stage, particularly at the G1 phase. PMID:19729042

Proliferative effects of estradiol- or ethinylestradiol-progestogen combinations on human breast cancer cells in an intermitted and a long-term regimen.

PubMed

Merki-Feld, G S; Seeger, H; Mueck, A O

2012-06-01

Currently the use of natural estradiol as estrogenic component in oral contraceptives is more and more extended. It is unknown whether the application of this estrogen is associated with a different breast cancer risk as compared to the common use of the synthetic ethinylestradiol. In addition with the intention to reduce menstruation associated symptoms and bleeding periods an extended-cycle regimen is currently considered. In the present in vitro work, we have compared the effect of these different estrogenic compounds and the different treatment regimens on breast cancer risk. Human breast cancer cells (ZR75-1 and HCC1500) were incubated with equimolar concentrations of estradiol or ethinylestradiol combined with various progestogens, dienogest, drospirenone, keto-desogestrel, levonorgestrel, and nomegestrel. Usual and extended cycle was mimicked by incubation periods of 3 days with 1 day hormones off and 4 days, respectively. Molecular markers for proliferation and apoptosis were investigated by Western blot. In both cell lines estradiol and ethinylestradiol elicited a significant increase in the proliferation rate without difference between the 2 estrogens. The effect in the long-term cycle tended to be more pronounced than in the intermitted cycle. Progestogen addition most significantly reduced the estrogen-induced proliferation rate. The molecular markers were influenced by the progestogens mostly in the same manner, reducing the proliferation/apoptosis rate. Our results indicate that both estrogenic based combinations with progestogens may not increase breast cancer risk independent from the regimen, intermitted or long-term cycle. However clinical studies are necessary to prove these in vitro results. © Georg Thieme Verlag KG Stuttgart · New York.

Strategies of biochemical adaptation for hibernation in a South American marsupial, Dromiciops gliroides: 3. Activation of pro-survival response pathways.

PubMed

Luu, Bryan E; Wijenayake, Sanoji; Zhang, Jing; Tessier, Shannon N; Quintero-Galvis, Julian F; Gaitán-Espitia, Juan Diego; Nespolo, Roberto F; Storey, Kenneth B

2017-12-15

The South American marsupial, monito del monte (Dromiciops gliroides) uses both daily torpor and multi-day hibernation to survive in its southern Chile native environment. The present study leverages multiplex technology to assess the contributions of key stress-inducible cell cycle regulators and heat shock proteins to hibernation in liver, heart, and brain of monito del monte in a comparison of control versus 4day hibernating conditions. The data indicate that MDM2, a stress-responsive ubiquitin ligase, plays a crucial role in marsupial hibernation since all three tissues showed statistically significant increases in MDM2 levels during torpor (1.6-1.8 fold). MDM2 may have a cytoprotective action to deal with ischemia/reperfusion stress and is also involved in a nutrient sensing pathway where it could help regulate the metabolic switch to fatty acid oxidation during torpor. Elevated levels of stress-sensitive cell cycle regulators including ATR (2.32-3.91 fold), and the phosphorylated forms of p-Chk1 (Ser345) (1.92 fold), p-Chk2 (Thr68) (2.20 fold) and p21 (1.64 fold) were observed in heart and liver during hibernation suggesting that the cell cycle is likely suppressed to conserve energy while animals are in torpor. Upregulation of heat shock proteins also occurred as a cytoprotective strategy with increased levels of hsp27 (2.00 fold) and hsp60 (1.72-2.76 fold) during hibernation. The results suggest that cell cycle control and selective chaperone action are significant components of hibernation in D. gliroides and reveal common molecular responses to those seen in eutherian hibernators. Copyright © 2017 Elsevier Inc. All rights reserved.

Analysis of Septin Reorganization at Cytokinesis Using Polarized Fluorescence Microscopy

PubMed Central

McQuilken, Molly; Jentzsch, Maximilian S.; Verma, Amitabh; Mehta, Shalin B.; Oldenbourg, Rudolf; Gladfelter, Amy S.

2017-01-01

Septins are conserved filament-forming proteins that act in diverse cellular processes. They closely associate with membranes and, in some systems, components of the cytoskeleton. It is not well understood how filaments assemble into higher-order structures in vivo or how they are remodeled throughout the cell cycle. In the budding yeast S. cerevisiae, septins are found through most of the cell cycle in an hourglass organization at the mother-bud neck until cytokinesis when the collar splits into two rings that disassemble prior to the next cell cycle. Experiments using polarized fluorescence microscopy have suggested that septins are arranged in ordered, paired filaments in the hourglass and undergo a coordinated 90° reorientation during splitting at cytokinesis. This apparent reorganization could be due to two orthogonal populations of filaments disassembling and reassembling or being preferentially retained at cytokinesis. In support of this idea, we report a decrease in septin concentration at the mother-bud neck during cytokinesis consistent with other reports and the timing of the decrease depends on known septin regulators including the Gin4 kinase. We took a candidate-based approach to examine what factors control reorientation during splitting and used polarized fluorescence microscopy to screen mutant yeast strains deficient in septin interacting proteins. Using this method, we have linked known septin regulators to different aspects of the assembly, stability, and reorganization of septin assemblies. The data support that ring splitting requires Gin4 activity and an anillin-like protein Bud4, and normal accumulation of septins at the ring requires phosphorylation of Shs1. We found distinct regulatory requirements for septin organization in the hourglass compared to split rings. We propose that septin subpopulations can vary in their localization and assembly/disassembly behavior in a cell-cycle dependent manner at cytokinesis. PMID:28516085

Genetic bases of fungal white rot wood decay predicted by phylogenomic analysis of correlated gene-phenotype evolution

Treesearch

László G. Nagy; Robert Riley; Philip J. Bergmann; Krisztina Krizsán; Francis M. Martin; Igor V. Grigoriev; Dan Cullen; David S. Hibbett

2016-01-01

Fungal decomposition of plant cell walls (PCW) is a complex process that has diverse industrial applications and huge impacts on the carbon cycle. White rot (WR) is a powerful mode of PCW decay in which lignin and carbohydrates are both degraded. Mechanistic studies of decay coupled with comparative genomic analyses have provided clues to the enzymatic components of WR...

Prestin-based outer hair cell electromotility in knockin mice does not appear to adjust the operating point of a cilia-based amplifier

PubMed Central

Gao, Jiangang; Wang, Xiang; Wu, Xudong; Aguinaga, Sal; Huynh, Kristin; Jia, Shuping; Matsuda, Keiji; Patel, Manish; Zheng, Jing; Cheatham, MaryAnn; He, David Z.; Dallos, Peter; Zuo, Jian

2007-01-01

The remarkable sensitivity and frequency selectivity of the mammalian cochlea is attributed to a unique amplification process that resides in outer hair cells (OHCs). Although the mammalian-specific somatic motility is considered a substrate of cochlear amplification, it has also been proposed that somatic motility in mammals simply acts as an operating-point adjustment for the ubiquitous stereocilia-based amplifier. To address this issue, we created a mouse model in which a mutation (C1) was introduced into the OHC motor protein prestin, based on previous results in transfected cells. In C1/C1 knockin mice, localization of C1-prestin, as well as the length and number of OHCs, were all normal. In OHCs isolated from C1/C1 mice, nonlinear capacitance and somatic motility were both shifted toward hyperpolarization, so that, compared with WT controls, the amplitude of cycle-by-cycle (alternating, or AC) somatic motility remained the same, but the unidirectional (DC) component reversed polarity near the OHC's presumed in vivo resting membrane potential. No physiological defects in cochlear sensitivity or frequency selectivity were detected in C1/C1 or C1/+ mice. Hence, our results do not support the idea that OHC somatic motility adjusts the operating point of a stereocilia-based amplifier. However, they are consistent with the notion that the AC component of OHC somatic motility plays a dominant role in mammalian cochlear amplification. PMID:17640919

The histone acetyltransferase component TRRAP is targeted for destruction during the cell cycle.

PubMed

Ichim, G; Mola, M; Finkbeiner, M G; Cros, M-P; Herceg, Z; Hernandez-Vargas, H

2014-01-09

Chromosomes are dynamic structures that must be reversibly condensed and unfolded to accommodate mitotic division and chromosome segregation. Histone modifications are involved in the striking chromatin reconfiguration taking place during mitosis. However, the mechanisms that regulate activity and function of histone-modifying factors as cells enter and exit mitosis are poorly understood. Here, we show that the anaphase-promoting complex or cyclosome (APC/C) is involved in the mitotic turnover of TRRAP (TRansformation/tRanscription domain-Associated Protein), a common component of histone acetyltransferase (HAT) complexes, and that the pre-mitotic degradation of TRRAP is mediated by the APC/C ubiquitin ligase activators Cdc20 and Cdh1. Ectopic expression of both Cdh1 and Cdc20 reduced the levels of coexpressed TRRAP protein and induced its ubiquitination. TRRAP overexpression or stabilization induces multiple mitotic defects, including lagging chromosomes, chromosome bridges and multipolar spindles. In addition, lack of sister chromatid cohesion and impaired chromosome condensation were found after TRRAP overexpression or stabilization. By using a truncated form of TRRAP, we show that mitotic delay is associated with a global histone H4 hyperacetylation induced by TRRAP overexpression. These results demonstrate that the chromatin modifier TRRAP is targeted for destruction in a cell cycle-dependent fashion. They also suggest that degradation of TRRAP by the APC/C is necessary for a proper condensation of chromatin and proper chromosome segregation. Chromatin compaction mediated by histone modifiers may represent a fundamental arm for APC/C orchestration of the mitotic machinery.

Testicular seminomatous mixed germ cell tumor with choriocarcinoma and teratoma with secondary somatic malignancy: a case report.

PubMed

Aneja, Amandeep; Bhattacharyya, Siddharth; Mydlo, Jack; Inniss, Susan

2014-01-01

Testicular tumors are a heterogeneous group of neoplasms exhibiting diverse histopathology and can be classified as seminomatous and non-seminomatous germ cell tumor types. Mixed germ cell tumors contain more than one germ cell component and various combinations have been reported. Here, we present a rare case of a mixed germ cell tumor composed of seminoma, choriocarcinoma and teratoma with a secondary somatic malignancy. A 31-year-old Caucasian man presented with splenic rupture to our hospital. A right-sided testicular swelling had been present for 6 months and his alpha-fetoprotein, beta-human chorionic gonadotropin, and lactose dehydrogenase were increased. An ultrasound of his scrotum revealed an enlarged right testis with heterogeneous echogenicity. Multiple hypervascular lesions were noted in his liver and spleen. He underwent transcatheter embolization therapy of his splenic artery followed by splenectomy and right-sided orchiectomy. A computed tomography scan also showed metastasis to both lungs. During his last follow up after four cycles of cisplatin-based chemotherapy, the level of tumor markers had decreased, decreases in the size of his liver and pulmonary lesions were noted but new sclerotic lesions were evident in his thoracolumbar region raising concern for bony metastasis. Prognosis of testicular tumor depends mainly on the clinical stage, but emergence of a sarcomatous component presents a challenge in the treatment of germ cell tumors and the histological subtype of this component can be used as a guide to specific chemotherapy in these patients.

Water-soluble cationic derivatives of indirubin, the active anticancer component from Indigo naturalis.

PubMed

Ginzinger, Werner; Egger, Alexander; Mühlgassner, Gerhard; Arion, Vladimir B; Jakupec, Michael A; Galanski, Markus; Berger, Walter; Keppler, Bernhard K

2012-10-01

To overcome the problem of poor aqueous solubility and bioavailability of indirubin-3-oximes, the compounds were modified by attaching a quaternary ammonium group at the oxime moiety. Exploring the prodrug concept, an oxime ester with acetyl-l-carnitine was prepared, and the rate of its hydrolysis was investigated to assess its suitability for clinical administration. In addition, the cytotoxic potency of new stable oxime ethers with a choline moiety and their influence on the cell cycle were tested in human cancer cell lines. Copyright © 2012 Verlag Helvetica Chimica Acta AG, Zürich.

Statistical indicators of collective behavior and functional clusters in gene networks of yeast

NASA Astrophysics Data System (ADS)

Živković, J.; Tadić, B.; Wick, N.; Thurner, S.

2006-03-01

We analyze gene expression time-series data of yeast (S. cerevisiae) measured along two full cell-cycles. We quantify these data by using q-exponentials, gene expression ranking and a temporal mean-variance analysis. We construct gene interaction networks based on correlation coefficients and study the formation of the corresponding giant components and minimum spanning trees. By coloring genes according to their cell function we find functional clusters in the correlation networks and functional branches in the associated trees. Our results suggest that a percolation point of functional clusters can be identified on these gene expression correlation networks.

Alteration of cell cycle progression by Sindbis virus infection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yi, Ruirong; Saito, Kengo; Isegawa, Naohisa

We examined the impact of Sindbis virus (SINV) infection on cell cycle progression in a cancer cell line, HeLa, and a non-cancerous cell line, Vero. Cell cycle analyses showed that SINV infection is able to alter the cell cycle progression in both HeLa and Vero cells, but differently, especially during the early stage of infection. SINV infection affected the expression of several cell cycle regulators (CDK4, CDK6, cyclin E, p21, cyclin A and cyclin B) in HeLa cells and caused HeLa cells to accumulate in S phase during the early stage of infection. Monitoring SINV replication in HeLa and Veromore » cells expressing cell cycle indicators revealed that SINV which infected HeLa cells during G{sub 1} phase preferred to proliferate during S/G{sub 2} phase, and the average time interval for viral replication was significantly shorter in both HeLa and Vero cells infected during G{sub 1} phase than in cells infected during S/G{sub 2} phase. - Highlights: • SINV infection was able to alter the cell cycle progression of infected cancer cells. • SINV infection can affect the expression of cell cycle regulators. • SINV infection exhibited a preference for the timing of viral replication among the cell cycle phases.« less

Loss of DDB1 Leads to Transcriptional p53 Pathway Activation in Proliferating Cells, Cell Cycle Deregulation, and Apoptosis in Zebrafish Embryos.

PubMed

Hu, Zhilian; Holzschuh, Jochen; Driever, Wolfgang

2015-01-01

DNA damage-binding protein 1 (DDB1) is a large subunit of the heterodimeric DDB complex that recognizes DNA lesions and initiates the nucleotide excision repair process. DDB1 is also a component of the CUL4 E3 ligase complex involved in a broad spectrum of cellular processes by targeted ubiquitination of key regulators. Functions of DDB1 in development have been addressed in several model organisms, however, are not fully understood so far. Here we report an ENU induced mutant ddb1 allele (ddb1m863) identified in zebrafish (Danio rerio), and analyze its effects on development. Zebrafish ddb1 is expressed broadly, both maternally and zygotically, with enhanced expression in proliferation zones. The (ddb1m863 mutant allele affects the splice acceptor site of exon 20, causing a splicing defect that results in truncation of the 1140 amino acid protein after residue 800, lacking part of the β-propeller domain BPC and the C-terminal helical domain CTD. ddb1m863 zygotic mutant embryos have a pleiotropic phenotype, including smaller and abnormally shaped brain, head skeleton, eyes, jaw, and branchial arches, as well as reduced dopaminergic neuron groups. However, early forming tissues develop normally in zygotic ddb1m863 mutant embryos, which may be due to maternal rescue. In ddb1m863 mutant embryos, pcna-expressing proliferating cell populations were reduced, concurrent with increased apoptosis. We also observed a concomitant strong up-regulation of transcripts of the tumor suppressor p53 (tp53) and the cell cycle inhibitor cdkn1a (p21a/bCIP1/WAF1) in proliferating tissues. In addition, transcription of cyclin genes ccna2 and ccnd1 was deregulated in ddb1m863 mutants. Reduction of p53 activity by anti-sense morpholinos alleviated the apoptotic phenotype in ddb1m863 mutants. These results imply that Ddb1 may be involved in maintaining proper cell cycle progression and viability of dividing cells during development through transcriptional mechanisms regulating genes involved in cell cycle control and cell survival.

Culture Medium Supplements Derived from Human Platelet and Plasma: Cell Commitment and Proliferation Support

PubMed Central

Muraglia, Anita; Nguyen, Van Thi; Nardini, Marta; Mogni, Massimo; Coviello, Domenico; Dozin, Beatrice; Strada, Paolo; Baldelli, Ilaria; Formica, Matteo; Cancedda, Ranieri; Mastrogiacomo, Maddalena

2017-01-01

Present cell culture medium supplements, in most cases based on animal sera, are not fully satisfactory especially for the in vitro expansion of cells intended for human cell therapy. This paper refers to (i) an heparin-free human platelet lysate (PL) devoid of serum or plasma components (v-PL) and (ii) an heparin-free human serum derived from plasma devoid of PL components (Pl-s) and to their use as single components or in combination in primary or cell line cultures. Human mesenchymal stem cells (MSC) primary cultures were obtained from adipose tissue, bone marrow, and umbilical cord. Human chondrocytes were obtained from articular cartilage biopsies. In general, MSC expanded in the presence of Pl-s alone showed a low or no proliferation in comparison to cells grown with the combination of Pl-s and v-PL. Confluent, growth-arrested cells, either human MSC or human articular chondrocytes, treated with v-PL resumed proliferation, whereas control cultures, not supplemented with v-PL, remained quiescent and did not proliferate. Interestingly, signal transduction pathways distinctive of proliferation were activated also in cells treated with v-PL in the absence of serum, when cell proliferation did not occur, indicating that v-PL could induce the cell re-entry in the cell cycle (cell commitment), but the presence of serum proteins was an absolute requirement for cell proliferation to happen. Indeed, Pl-s alone supported cell growth in constitutively activated cell lines (U-937, HeLa, HaCaT, and V-79) regardless of the co-presence of v-PL. Plasma- and plasma-derived serum were equally able to sustain cell proliferation although, for cells cultured in adhesion, the Pl-s was more efficient than the plasma from which it was derived. In conclusion, the cells expanded in the presence of the new additives maintained their differentiation potential and did not show alterations in their karyotype. PMID:29209609

The Roles of 4β-Hydroxywithanolide E from Physalis peruviana on the Nrf2-Anti-Oxidant System and the Cell Cycle in Breast Cancer Cells.

PubMed

Peng, Chieh Yu; You, Bang Jau; Lee, Chia Lin; Wu, Yang Chang; Lin, Wen Hsin; Lu, Te Ling; Chang, Fei-Ching; Lee, Hong Zin

2016-01-01

4[Formula: see text]-Hydroxywithanolide E is an active component of the extract of Physalis peruviana that has been reported to exhibit antitumor effects. Although the involvement of reactive oxygen species (ROS) production and the ataxia-telangiectasia mutated protein (ATM)-dependent DNA damage signaling pathway in 4[Formula: see text]-hydroxywithanolide E-induced apoptosis of breast cancer MCF-7 cells was demonstrated in our previous study, the relationship between ROS production and the cellular defense system response in 4[Formula: see text]-hydroxywithanolide E-induced cell death requires further verification. The present study suggests that ROS play an important role in 4[Formula: see text]-hydroxywithanolide E-induced MCF-7 cell death in which anti-oxidants, such as glutathione or N-acetylcysteine, can resist the 4[Formula: see text]-hydroxywithanolide E-induced accumulation of ROS and cell death. Furthermore, N-acetylcysteine or glutathione can reverse the 4[Formula: see text]-hydroxywithanolide E-induced changes in the cell cycle distribution and the expression of cell cycle regulators. We found that the 4[Formula: see text]-hydroxywithanolide E-induced ROS accumulation was correlated with the upregulation of Nrf2 and Nrf2-downstream genes, such as antioxidative defense enzymes. In general, the activity of Nrf2 is regulated by the Ras signalling pathway. However, we demonstrated that Nrf2 was activated during 4[Formula: see text]-hydroxywithanolide E-induced MCF-7 cell death in spite of the 4[Formula: see text]-hydroxywithanolide E-induced inhibition of the Ras/Raf/ERK pathway. The activity and protein expression of superoxide dismutase and catalase were involved in the 4[Formula: see text]-hydroxywithanolide E-induced ROS production in MCF-7 cells. Furthermore, 4[Formula: see text]-hydroxywithanolide E was demonstrated to significantly reduce the sizes of the tumor nodules in the human breast cancer MDA-MB231 xenograft tumor model.

The soy-derived peptide Vglycin inhibits the growth of colon cancer cells in vitro and in vivo.

PubMed

Gao, Chang; Sun, Rui; Xie, Ya-Rong; Jiang, An-Li; Lin, Mei; Li, Min; Chen, Zheng-Wang; Zhang, Ping; Jin, Honglin; Feng, Jue-Ping

2017-05-01

Vglycin, a novel natural polypeptide isolated from pea seeds, possesses antidiabetic properties. Our previous studies have shown that Vglycin can induce the differentiation of human colon adenocarcinoma cells. We aimed to determine the anticancer activity of Vglycin against colon cancer cells and to elucidate related apoptosis-inducing mechanisms. Treatment with purified Vglycin significantly reduced growth, viability, and colony formation of CT-26, SW480, and NCL-H716 colon cancer cells in a dose-dependent manner while down-regulating the expression of proliferating cell nuclear antigen. Mouse xenograft studies showed a 38% inhibition of colon cancer growth in mice treated with Vglycin (20 mg/kg/day) at day 21. Furthermore, the potential mechanisms involved in Vglycin-induced cell apoptosis were examined using cell cycle studies, ultrastructural examination, as well as apoptosis-associated pathway analysis. The results showed that Vglycin significantly promoted apoptosis and G1/S phase cell cycle arrest. As revealed by Western blot, the expression of CDK2 and Cyclin D1 was down-regulated in all three Vglycin-treated colon cancer cells, indicating that the CDK2/Cyclin D1 cell cycle pathway involved in the initiation and progression of colon cancer. Moreover, the inhibition of Vglycin-induced cell proliferation in colon cancer cells was accompanied by alteration of the expression levels of the apoptosis-related proteins Bax, Bcl-2 and Mcl-1, and an increase of caspase-3 activity. Together, our results suggest that Vglycin may be another plant-derived peptide that suppresses colon cancer, supporting the continued investigation of Vglycin as therapeutic agent for colon cancer. Impact statement The antidiabetic properties and the capability of inducing differentiation of human colon adenocarcinoma cells of Vglycin have been reported in our previous studies. However, the anticancer potential of Vglycin on colon cancer cells and its possible related mechanisms were still unknown. In this study, we found that Vglycin could reduce growth, viability, and colony formation or colony size of CT-26, SW480, and NCL-H716 colon cancer cells. Moreover, Vglycin decreased tumor volume by 38% in xenograft mice transplanted with CT-26 cells. The mechanisms of these phenomena may be due to the down-regulated CDK2 and Cyclin D1, G1/S phase cell cycle arrest, and the dysregulated expression of Bax, Bcl-2, and Mcl-1. The findings highlight the anticancer potential of Vglycin against colon cancer cells, and suggest Vglycin may be another colon cancer potential suppressive component of plant-derived peptides.

Layered sulfur/PEDOT:PSS nano composite electrodes for lithium sulfur cell applications

NASA Astrophysics Data System (ADS)

Anilkumar, K. M.; Jinisha, B.; Manoj, M.; Pradeep, V. S.; Jayalekshmi, S.

2018-06-01

Lithium-Sulfur (Li-S) cells are emerging as the next generation energy storage devices owing to their impressive electrochemical properties with high theoretical specific capacity of 1675 mAh/g. Lack of electronic conductivity of sulfur, its volume expansion during high lithium intake and the shuttling effect due to the formation of soluble polysulfides are the main limitations, delaying the commercialization of this technology. To address these challenges, in the present work, the conducting polymer PEDOT:PSS is used as the covering matrix over the sulfur particles to improve their Li storage properties. The sulfur/PEDOT:PSS nanocomposite is synthesised using the hydrothermal process and its formation with the polymer coating over sulfur nanoparticles is established from the XRD, Raman spectroscopy, FE-SEM and TEM studies. The electrochemical studies show that the cells assembled using the sulfur/PEDOT:PSS nanocomposite as the cathode, with the components taken in the weight ratio of 9:1, offer a reversible capacity of 1191 mAh g-1 at 0.1C rate. These cells display stable electrochemical capacities over 200 cycles at gradually increasing current rates. The polymer layer facilitates electronic conduction and suppresses the polysulfide formation and the volume expansion of sulfur. A reversible capacity of 664 mAh g-1 is observed after 200 cycles at 1C rate with the capacity retention of 75 % of the initial stable capacity. The highlight of the present work is the possibility to achieve high discharge capacities at high C rates and the retention of a good percentage of the initial capacity over 200 cycles, for these Li-S cells.

Efficiency measurement and uncertainty discussion of an electric engine powered by a ``self-breathing'' and ``self-humidified'' proton exchange membrane fuel cell

NASA Astrophysics Data System (ADS)

Schiavetti, Pierluigi; Del Prete, Zaccaria

2007-08-01

The efficiency of an automotive engine based on a "self-breathing" and "self-humidified" proton exchange membrane fuel cell stack (PEM FC) connected to a dc brushless electrical motor was measured under variable power load conditions. Experiments have been carried out on a small scale 150W engine model. After determining the fuel cell static polarization curve and the time response to power steps, the system was driven to copy on the test bench a "standard urban load cycle" and its instantaneous efficiencies were measured at an acquisition rate of 5Hz. The integral system efficiency over the entire urban load cycle, comprising the losses of the unavoidable auxiliary components of the engine, was then calculated. The fuel cell stack was operated mainly in "partial" dead-end mode, with a periodic anode flow channel purging, and one test was carried out in "pure" dead-end mode, with no anode channel purging. An uncertainty analysis of the efficiencies was carried out, taking into account either type A and type B evaluation methods, strengthening the discussion about the outcomes obtained for a system based on this novel simplified FC type. For our small scale engine we measured over the standard urban cycle, on the basis of the H2 high heating value (HHV), a tank-to-wheel integral efficiency of (18.2±0.8)%, when the fuel cell was operated with periodic flow channel purging, and of (21.5±1.3)% in complete dead-end operation mode.

Efficiency measurement and uncertainty discussion of an electric engine powered by a "self-breathing" and "self-humidified" proton exchange membrane fuel cell.

PubMed

Schiavetti, Pierluigi; Del Prete, Zaccaria

2007-08-01

The efficiency of an automotive engine based on a "self-breathing" and "self-humidified" proton exchange membrane fuel cell stack (PEM FC) connected to a dc brushless electrical motor was measured under variable power load conditions. Experiments have been carried out on a small scale 150 W engine model. After determining the fuel cell static polarization curve and the time response to power steps, the system was driven to copy on the test bench a "standard urban load cycle" and its instantaneous efficiencies were measured at an acquisition rate of 5 Hz. The integral system efficiency over the entire urban load cycle, comprising the losses of the unavoidable auxiliary components of the engine, was then calculated. The fuel cell stack was operated mainly in "partial" dead-end mode, with a periodic anode flow channel purging, and one test was carried out in "pure" dead-end mode, with no anode channel purging. An uncertainty analysis of the efficiencies was carried out, taking into account either type A and type B evaluation methods, strengthening the discussion about the outcomes obtained for a system based on this novel simplified FC type. For our small scale engine we measured over the standard urban cycle, on the basis of the H(2) high heating value (HHV), a tank-to-wheel integral efficiency of (18.2+/-0.8)%, when the fuel cell was operated with periodic flow channel purging, and of (21.5+/-1.3)% in complete dead-end operation mode.

Signaling molecules involved in the transition of growth to development of Dictyostelium discoideum.

PubMed

Mir, Hina A; Rajawat, Jyotika; Pradhan, Shalmali; Begum, Rasheedunnisa

2007-03-01

The social amoeba Dictyostelium discoideum, a powerful paradigm provides clear insights into the regulation of growth and development. In addition to possessing complex individual cellular functions like a unicellular eukaryote, D. discoideum cells face the challenge of multicellular development. D. discoideum undergoes a relatively simple differentiation process mainly by cAMP mediated pathway. Despite this relative simplicity, the regulatory signaling pathways are as complex as those seen in metazoan development. However, the introduction of restriction-enzyme-mediated integration (REMI) technique to produce developmental gene knockouts has provided novel insights into the discovery of signaling molecules and their role in D. discoideum development. Cell cycle phase is an important aspect for differentiation of D. discoideum, as cells must reach a specific stage to enter into developmental phase and specific cell cycle regulators are involved in arresting growth phase genes and inducing the developmental genes. In this review, we present an overview of the signaling molecules involved in the regulation of growth to differentiation transition (GDT), molecular mechanism of early developmental events leading to generation of cAMP signal and components of cAMP relay system that operate in this paradigm.

Quantitative imaging with Fucci and mathematics to uncover temporal dynamics of cell cycle progression.

PubMed

Saitou, Takashi; Imamura, Takeshi

2016-01-01

Cell cycle progression is strictly coordinated to ensure proper tissue growth, development, and regeneration of multicellular organisms. Spatiotemporal visualization of cell cycle phases directly helps us to obtain a deeper understanding of controlled, multicellular, cell cycle progression. The fluorescent ubiquitination-based cell cycle indicator (Fucci) system allows us to monitor, in living cells, the G1 and the S/G2/M phases of the cell cycle in red and green fluorescent colors, respectively. Since the discovery of Fucci technology, it has found numerous applications in the characterization of the timing of cell cycle phase transitions under diverse conditions and various biological processes. However, due to the complexity of cell cycle dynamics, understanding of specific patterns of cell cycle progression is still far from complete. In order to tackle this issue, quantitative approaches combined with mathematical modeling seem to be essential. Here, we review several studies that attempted to integrate Fucci technology and mathematical models to obtain quantitative information regarding cell cycle regulatory patterns. Focusing on the technological development of utilizing mathematics to retrieve meaningful information from the Fucci producing data, we discuss how the combined methods advance a quantitative understanding of cell cycle regulation. © 2015 Japanese Society of Developmental Biologists.

Reciprocal signalling by Notch-Collagen V-CALCR retains muscle stem cells in their niche.

PubMed

Baghdadi, Meryem B; Castel, David; Machado, Léo; Fukada, So-Ichiro; Birk, David E; Relaix, Frederic; Tajbakhsh, Shahragim; Mourikis, Philippos

2018-05-01

The cell microenvironment, which is critical for stem cell maintenance, contains both cellular and non-cellular components, including secreted growth factors and the extracellular matrix 1-3 . Although Notch and other signalling pathways have previously been reported to regulate quiescence of stem cells 4-9 , the composition and source of molecules that maintain the stem cell niche remain largely unknown. Here we show that adult muscle satellite (stem) cells in mice produce extracellular matrix collagens to maintain quiescence in a cell-autonomous manner. Using chromatin immunoprecipitation followed by sequencing, we identified NOTCH1/RBPJ-bound regulatory elements adjacent to specific collagen genes, the expression of which is deregulated in Notch-mutant mice. Moreover, we show that Collagen V (COLV) produced by satellite cells is a critical component of the quiescent niche, as depletion of COLV by conditional deletion of the Col5a1 gene leads to anomalous cell cycle entry and gradual diminution of the stem cell pool. Notably, the interaction of COLV with satellite cells is mediated by the Calcitonin receptor, for which COLV acts as a surrogate local ligand. Systemic administration of a calcitonin derivative is sufficient to rescue the quiescence and self-renewal defects found in COLV-null satellite cells. This study reveals a Notch-COLV-Calcitonin receptor signalling cascade that maintains satellite cells in a quiescent state in a cell-autonomous fashion, and raises the possibility that similar reciprocal mechanisms act in diverse stem cell populations.

Cell Cycle Control in the Early Embryonic Development of Aquatic Animal Species

PubMed Central

Siefert, Joseph C.; Clowdus, Emily A.; Sansam, Christopher L.

2016-01-01

The cell cycle is integrated with many aspects of embryonic development. Not only is proper control over the pace of cell proliferation important, but also the timing of cell cycle progression is coordinated with transcription, cell migration, and cell differentiation. Due to the ease with which the embryos of aquatic organisms can be observed and manipulated, they have been a popular choice for embryologists throughout history. In the cell cycle field, aquatic organisms have been extremely important because they have played a major role in the discovery and analysis of key regulators of the cell cycle. In particular, the frog Xenopus laevis has been instrumental for understanding how the basic embryonic cell cycle is regulated. More recently, the zebrafish has been used to understand how the cell cycle is remodeled during vertebrate development and how it is regulated during morphogenesis. This review describes how some of the unique strengths of aquatic species have been leveraged for cell cycle research and suggests how species such as Xenopus and zebrafish will continue to reveal the roles of the cell cycle in human biology and disease. PMID:26475527

Human T-lymphotropic virus type 1-infected cells secrete exosomes that contain Tax protein.

PubMed

Jaworski, Elizabeth; Narayanan, Aarthi; Van Duyne, Rachel; Shabbeer-Meyering, Shabana; Iordanskiy, Sergey; Saifuddin, Mohammed; Das, Ravi; Afonso, Philippe V; Sampey, Gavin C; Chung, Myung; Popratiloff, Anastas; Shrestha, Bindesh; Sehgal, Mohit; Jain, Pooja; Vertes, Akos; Mahieux, Renaud; Kashanchi, Fatah

2014-08-08

Human T-lymphotropic virus type 1 (HTLV-1) is the causative agent of adult T-cell leukemia and HTLV-1-associated myelopathy/tropical spastic paraparesis. The HTLV-1 transactivator protein Tax controls many critical cellular pathways, including host cell DNA damage response mechanisms, cell cycle progression, and apoptosis. Extracellular vesicles called exosomes play critical roles during pathogenic viral infections as delivery vehicles for host and viral components, including proteins, mRNA, and microRNA. We hypothesized that exosomes derived from HTLV-1-infected cells contain unique host and viral proteins that may contribute to HTLV-1-induced pathogenesis. We found exosomes derived from infected cells to contain Tax protein and proinflammatory mediators as well as viral mRNA transcripts, including Tax, HBZ, and Env. Furthermore, we observed that exosomes released from HTLV-1-infected Tax-expressing cells contributed to enhanced survival of exosome-recipient cells when treated with Fas antibody. This survival was cFLIP-dependent, with Tax showing induction of NF-κB in exosome-recipient cells. Finally, IL-2-dependent CTLL-2 cells that received Tax-containing exosomes were protected from apoptosis through activation of AKT. Similar experiments with primary cultures showed protection and survival of peripheral blood mononuclear cells even in the absence of phytohemagglutinin/IL-2. Surviving cells contained more phosphorylated Rb, consistent with the role of Tax in regulation of the cell cycle. Collectively, these results suggest that exosomes may play an important role in extracellular delivery of functional HTLV-1 proteins and mRNA to recipient cells. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Human T-lymphotropic Virus Type 1-infected Cells Secrete Exosomes That Contain Tax Protein*

PubMed Central

Jaworski, Elizabeth; Narayanan, Aarthi; Van Duyne, Rachel; Shabbeer-Meyering, Shabana; Iordanskiy, Sergey; Saifuddin, Mohammed; Das, Ravi; Afonso, Philippe V.; Sampey, Gavin C.; Chung, Myung; Popratiloff, Anastas; Shrestha, Bindesh; Sehgal, Mohit; Jain, Pooja; Vertes, Akos; Mahieux, Renaud; Kashanchi, Fatah

2014-01-01

Human T-lymphotropic virus type 1 (HTLV-1) is the causative agent of adult T-cell leukemia and HTLV-1-associated myelopathy/tropical spastic paraparesis. The HTLV-1 transactivator protein Tax controls many critical cellular pathways, including host cell DNA damage response mechanisms, cell cycle progression, and apoptosis. Extracellular vesicles called exosomes play critical roles during pathogenic viral infections as delivery vehicles for host and viral components, including proteins, mRNA, and microRNA. We hypothesized that exosomes derived from HTLV-1-infected cells contain unique host and viral proteins that may contribute to HTLV-1-induced pathogenesis. We found exosomes derived from infected cells to contain Tax protein and proinflammatory mediators as well as viral mRNA transcripts, including Tax, HBZ, and Env. Furthermore, we observed that exosomes released from HTLV-1-infected Tax-expressing cells contributed to enhanced survival of exosome-recipient cells when treated with Fas antibody. This survival was cFLIP-dependent, with Tax showing induction of NF-κB in exosome-recipient cells. Finally, IL-2-dependent CTLL-2 cells that received Tax-containing exosomes were protected from apoptosis through activation of AKT. Similar experiments with primary cultures showed protection and survival of peripheral blood mononuclear cells even in the absence of phytohemagglutinin/IL-2. Surviving cells contained more phosphorylated Rb, consistent with the role of Tax in regulation of the cell cycle. Collectively, these results suggest that exosomes may play an important role in extracellular delivery of functional HTLV-1 proteins and mRNA to recipient cells. PMID:24939845

Ailanthone Inhibits Huh7 Cancer Cell Growth via Cell Cycle Arrest and Apoptosis In Vitro and In Vivo

PubMed Central

Zhuo, Zhenjian; Hu, Jianyang; Yang, Xiaolin; Chen, Minfen; Lei, Xueping; Deng, Lijuan; Yao, Nan; Peng, Qunlong; Chen, Zhesheng; Ye, Wencai; Zhang, Dongmei

2015-01-01

While searching for natural anti-hepatocellular carcinoma (HCC) components in Ailanthus altissima, we discovered that ailanthone had potent antineoplastic activity against HCC. However, the molecular mechanisms underlying the antitumor effect of ailanthone on HCC have not been examined. In this study, the antitumor activity and the underlying mechanisms of ailanthone were evaluated in vitro and in vivo. Mechanistic studies showed that ailanthone induced G0/G1-phase cell cycle arrest, as indicated by decreased expression of cyclins and CDKs and increased expression of p21 and p27. Our results demonstrated that ailanthone triggered DNA damage characterized by activation of the ATM/ATR pathway. Moreover, ailanthone-induced cell death was associated with apoptosis, as evidenced by an increased ratio of cells in the subG1 phase and by PARP cleavage and caspase activation. Ailanthone-induced apoptosis was mitochondrion-mediated and involved the PI3K/AKT signaling pathway in Huh7 cells. In vivo studies demonstrated that ailanthone inhibited the growth and angiogenesis of tumor xenografts without significant secondary adverse effects, indicating its safety for treating HCC. In conclusion, our study is the first to report the efficacy of ailanthone against Huh7 cells and to elucidate its underlying molecular mechanisms. These findings suggest that ailanthone is a potential agent for the treatment of liver cancer. PMID:26525771

Functional characterization of CFI-402257, a potent and selective Mps1/TTK kinase inhibitor, for the treatment of cancer.

PubMed

Mason, Jacqueline M; Wei, Xin; Fletcher, Graham C; Kiarash, Reza; Brokx, Richard; Hodgson, Richard; Beletskaya, Irina; Bray, Mark R; Mak, Tak W

2017-03-21

Loss of cell-cycle control is a hallmark of human cancer. Cell-cycle checkpoints are essential for maintaining genome integrity and balanced growth and division. They are specifically deregulated in cancer cells and contain regulators that represent potential therapeutic targets. Monopolar spindle 1 (Mps1; also known as TTK protein kinase) is a core component of the spindle assembly checkpoint (SAC), a genome-surveillance mechanism that is important for cell survival, and has emerged as a candidate target for anticancer therapy. Here, we report the cellular and antitumor effects of CFI-402257, a potent (Mps1 K i = 0.09 ± 0.02 nM; cellular Mps1 EC 50 = 6.5 ± 0.5 nM), highly selective, and orally active small-molecule inhibitor of Mps1 that was identified through a drug-discovery program. Human cancer cells treated with CFI-402257 exhibit effects consistent with Mps1 kinase inhibition, specifically SAC inactivation, leading to chromosome missegregation, aneuploidy, and ultimately cell death. Oral administration of CFI-402257 in monotherapy or in combination with an anti-programmed cell death 1 (PD-1) antibody in mouse models of human cancer results in inhibition of tumor growth at doses that are well-tolerated. Our findings provide a rationale for the clinical evaluation of CFI-402257 in patients with solid tumors.

Functional characterization of CFI-402257, a potent and selective Mps1/TTK kinase inhibitor, for the treatment of cancer

PubMed Central

Mason, Jacqueline M.; Wei, Xin; Fletcher, Graham C.; Kiarash, Reza; Brokx, Richard; Hodgson, Richard; Beletskaya, Irina; Bray, Mark R.; Mak, Tak W.

2017-01-01

Loss of cell-cycle control is a hallmark of human cancer. Cell-cycle checkpoints are essential for maintaining genome integrity and balanced growth and division. They are specifically deregulated in cancer cells and contain regulators that represent potential therapeutic targets. Monopolar spindle 1 (Mps1; also known as TTK protein kinase) is a core component of the spindle assembly checkpoint (SAC), a genome-surveillance mechanism that is important for cell survival, and has emerged as a candidate target for anticancer therapy. Here, we report the cellular and antitumor effects of CFI-402257, a potent (Mps1 Ki = 0.09 ± 0.02 nM; cellular Mps1 EC50 = 6.5 ± 0.5 nM), highly selective, and orally active small-molecule inhibitor of Mps1 that was identified through a drug-discovery program. Human cancer cells treated with CFI-402257 exhibit effects consistent with Mps1 kinase inhibition, specifically SAC inactivation, leading to chromosome missegregation, aneuploidy, and ultimately cell death. Oral administration of CFI-402257 in monotherapy or in combination with an anti-programmed cell death 1 (PD-1) antibody in mouse models of human cancer results in inhibition of tumor growth at doses that are well-tolerated. Our findings provide a rationale for the clinical evaluation of CFI-402257 in patients with solid tumors. PMID:28270606

Defibrotide interferes with several steps of the coagulation-inflammation cycle and exhibits therapeutic potential to treat severe malaria.

PubMed

Francischetti, Ivo M B; Oliveira, Carlo J; Ostera, Graciela R; Yager, Stephanie B; Debierre-Grockiego, Françoise; Carregaro, Vanessa; Jaramillo-Gutierrez, Giovanna; Hume, Jen C C; Jiang, Lubin; Moretz, Samuel E; Lin, Christina K; Ribeiro, José M C; Long, Carole A; Vickers, Brandi K; Schwarz, Ralph T; Seydel, Karl B; Iacobelli, Massimo; Ackerman, Hans C; Srinivasan, Prakash; Gomes, Regis B; Wang, Xunde; Monteiro, Robson Q; Kotsyfakis, Michail; Sá-Nunes, Anderson; Waisberg, Michael

2012-03-01

The coagulation-inflammation cycle has been implicated as a critical component in malaria pathogenesis. Defibrotide (DF), a mixture of DNA aptamers, displays anticoagulant, anti-inflammatory, and endothelial cell (EC)-protective activities and has been successfully used to treat comatose children with veno-occlusive disease. DF was investigated here as a drug to treat cerebral malaria. DF blocks tissue factor expression by ECs incubated with parasitized red blood cells and attenuates prothrombinase activity, platelet aggregation, and complement activation. In contrast, it does not affect nitric oxide bioavailability. We also demonstrated that Plasmodium falciparum glycosylphosphatidylinositol (Pf-GPI) induces tissue factor expression in ECs and cytokine production by dendritic cells. Notably, dendritic cells, known to modulate coagulation and inflammation systemically, were identified as a novel target for DF. Accordingly, DF inhibits Toll-like receptor ligand-dependent dendritic cells activation by a mechanism that is blocked by adenosine receptor antagonist (8-p-sulfophenyltheophylline) but not reproduced by synthetic poly-A, -C, -T, and -G. These results imply that aptameric sequences and adenosine receptor mediate dendritic cells responses to the drug. DF also prevents rosetting formation, red blood cells invasion by P. falciparum and abolishes oocysts development in Anopheles gambiae. In a murine model of cerebral malaria, DF affected parasitemia, decreased IFN-γ levels, and ameliorated clinical score (day 5) with a trend for increased survival. Therapeutic use of DF in malaria is proposed.

Cell cycle arrest in the jewel wasp Nasonia vitripennis in larval diapause.

PubMed

Shimizu, Yuta; Mukai, Ayumu; Goto, Shin G

2018-04-01

Insects enter diapause to synchronise their life cycle with biotic and abiotic environmental conditions favourable for their development, reproduction, and survival. One of the most noticeable characteristics of diapause is the blockage of ontogeny. Although this blockage should occur with the cessation of cellular proliferation, i.e. cell cycle arrest, it was confirmed only in a few insect species and information on the molecular pathways involved in cell cycle arrest is limited. In the present study, we investigated developmental and cell cycle arrest in diapause larvae of the jewel wasp Nasonia vitripennis. Developmental and cell cycle arrest occur in the early fourth instar larval stage of N. vitripennis under short days. By entering diapause, the S fraction of the cell cycle disappears and approximately 80% and 20% of cells arrest their cell cycle in the G0/G1 and G2 phases, respectively. We further investigated expression of cell cycle regulatory genes and some housekeeping genes to dissect molecular mechanisms underlying the cell cycle arrest. Copyright © 2016 Elsevier Ltd. All rights reserved.

Thermal characteristics of Lithium-ion batteries

NASA Technical Reports Server (NTRS)

Hauser, Dan

2004-01-01

Lithium-ion batteries have a very promising future for space applications. Currently they are being used on a few GEO satellites, and were used on the two recent Mars rovers Spirit and Opportunity. There are still problem that exist that need to be addressed before these batteries can fully take flight. One of the problems is that the cycle life of these batteries needs to be increased. battery. Research is being focused on the chemistry of the materials inside the battery. This includes the anode, cathode, and the cell electrolyte solution. These components can undergo unwanted chemical reactions inside the cell that deteriorate the materials of the battery. During discharge/ charge cycles there is heat dissipated in the cell, and the battery heats up and its temperature increases. An increase in temperature can speed up any unwanted reactions in the cell. Exothermic reactions cause the temperature to increase; therefore increasing the reaction rate will cause the increase of the temperature inside the cell to occur at a faster rate. If the temperature gets too high thermal runaway will occur, and the cell can explode. The material that separates the electrode from the electrolyte is a non-conducting polymer. At high temperatures the separator will melt and the battery will be destroyed. The separator also contains small pores that allow lithium ions to diffuse through during charge and discharge. High temperatures can cause these pores to close up, permanently damaging the cell. My job at NASA Glenn research center this summer will be to perform thermal characterization tests on an 18650 type lithium-ion battery. High temperatures cause the chemicals inside lithium ion batteries to spontaneously react with each other. My task is to conduct experiments to determine the temperature that the reaction takes place at, what components in the cell are reacting and the mechanism of the reaction. The experiments will be conducted using an accelerating rate calorimeter (ARC), which uses a heat-wait-search mode until an exothermic reaction is detected. After an exotherm is found the calorimeter maintains an adiabatic environment around a bomb which holds the test sample. The ARC will help identify important reactions and what temperature these exothermic reactions take place at. In order fully understand the battery, we are first going to take apart the battery and test the individual components of the battery using the ARC. I will first conduct a test on the electrolyte solution by itself. We will then test the electrolyte solution with the anode. We would like to see how the electrolyte solution reacts with the anode and its binder material. The next would be the same test using the cathode instead of the anode. By comparing the results of the electrolyte, electrolyte with anode, and the electrolyte with the cathode we can determine the reactions that are taking place due to each component. Using the heat capacity of the each individual sample and the temperature by which the sample increases, kinetic and thermo-dynamical information can then be found. A Gas chromatograph could be used to help with the task of identifying the by-products at the end of each test. One way of increasing the cycle life is to increase the stability of the materials inside the

Roll up nanowire battery from silicon chips

PubMed Central

Vlad, Alexandru; Reddy, Arava Leela Mohana; Ajayan, Anakha; Singh, Neelam; Gohy, Jean-François; Melinte, Sorin; Ajayan, Pulickel M.

2012-01-01

Here we report an approach to roll out Li-ion battery components from silicon chips by a continuous and repeatable etch-infiltrate-peel cycle. Vertically aligned silicon nanowires etched from recycled silicon wafers are captured in a polymer matrix that operates as Li+ gel-electrolyte and electrode separator and peeled off to make multiple battery devices out of a single wafer. Porous, electrically interconnected copper nanoshells are conformally deposited around the silicon nanowires to stabilize the electrodes over extended cycles and provide efficient current collection. Using the above developed process we demonstrate an operational full cell 3.4 V lithium-polymer silicon nanowire (LIPOSIL) battery which is mechanically flexible and scalable to large dimensions. PMID:22949696

A Module Experimental Process System Development Unit (MEPSDU)

NASA Technical Reports Server (NTRS)

1981-01-01

Subsequent to the design review, a series of tests was conducted on simulated modules to demonstrate that all environmental specifications (wind loading, hailstone impact, thermal cycling, and humidity cycling) are satisfied by the design. All tests, except hailstone impact, were successfully completed. The assembly sequence was simplified by virtue of eliminating the frame components and assembly steps. Performance was improved by reducing the module edge border required to accommodate the frame of the preliminary design module. An ultrasonic rolling spot bonding technique was selected for use in the machine to perform the aluminum interconnect to cell metallization electrical joints required in the MEPSDU module configuration. This selection was based on extensive experimental tests and economic analyses.

Reproduction of the FC/DFC units in nucleoli.

PubMed

Smirnov, Evgeny; Hornáček, Matúš; Kováčik, Lubomír; Mazel, Tomáš; Schröfel, Adam; Svidenská, Silvie; Skalníková, Magdalena; Bartová, Eva; Cmarko, Dušan; Raška, Ivan

2016-04-25

The essential structural components of the nucleoli, Fibrillar Centers (FC) and Dense Fibrillar Components (DFC), together compose FC/DFC units, loci of rDNA transcription and early RNA processing. In the present study we followed cell cycle related changes of these units in 2 human sarcoma derived cell lines with stable expression of RFP-PCNA (the sliding clamp protein) and GFP-RPA43 (a subunit of RNA polymerase I, pol I) or GFP-fibrillarin. Correlative light and electron microscopy analysis showed that the pol I and fibrillarin positive nucleolar beads correspond to individual FC/DFC units. In vivo observations showed that at early S phase, when transcriptionally active ribosomal genes were replicated, the number of the units in each cell increased by 60-80%. During that period the units transiently lost pol I, but not fibrillarin. Then, until the end of interphase, number of the units did not change, and their duplication was completed only after the cell division, by mid G1 phase. This peculiar mode of reproduction suggests that a considerable subset of ribosomal genes remain transcriptionally silent from mid S phase to mitosis, but become again active in the postmitotic daughter cells.

Defining Hsp70 Subnetworks in Dengue Virus Replication Reveals Key Vulnerability in Flavivirus Infection.

PubMed

Taguwa, Shuhei; Maringer, Kevin; Li, Xiaokai; Bernal-Rubio, Dabeiba; Rauch, Jennifer N; Gestwicki, Jason E; Andino, Raul; Fernandez-Sesma, Ana; Frydman, Judith

2015-11-19

Viral protein homeostasis depends entirely on the machinery of the infected cell. Accordingly, viruses can illuminate the interplay between cellular proteostasis components and their distinct substrates. Here, we define how the Hsp70 chaperone network mediates the dengue virus life cycle. Cytosolic Hsp70 isoforms are required at distinct steps of the viral cycle, including entry, RNA replication, and virion biogenesis. Hsp70 function at each step is specified by nine distinct DNAJ cofactors. Of these, DnaJB11 relocalizes to virus-induced replication complexes to promote RNA synthesis, while DnaJB6 associates with capsid protein and facilitates virion biogenesis. Importantly, an allosteric Hsp70 inhibitor, JG40, potently blocks infection of different dengue serotypes in human primary blood cells without eliciting viral resistance or exerting toxicity to the host cells. JG40 also blocks replication of other medically-important flaviviruses including yellow fever, West Nile and Japanese encephalitis viruses. Thus, targeting host Hsp70 subnetworks provides a path for broad-spectrum antivirals. Copyright © 2015 Elsevier Inc. All rights reserved.

Mec1/ATR, the Program Manager of Nucleic Acids Inc.

PubMed

Feng, Wenyi

2016-12-28

Eukaryotic cells are equipped with surveillance mechanisms called checkpoints to ensure proper execution of cell cycle events. Among these are the checkpoints that detect DNA damage or replication perturbations and coordinate cellular activities to maintain genome stability. At the forefront of damage sensing is an evolutionarily conserved molecule, known respectively in budding yeast and humans as Mec1 (Mitosis entry checkpoint 1) and ATR (Ataxia telangiectasia and Rad3-related protein). Through phosphorylation, Mec1/ATR activates downstream components of a signaling cascade to maintain nucleotide pool balance, protect replication fork integrity, regulate activation of origins of replication, coordinate DNA repair, and implement cell cycle delay. This list of functions continues to expand as studies have revealed that Mec1/ATR modularly interacts with various protein molecules in response to different cellular cues. Among these newly assigned functions is the regulation of RNA metabolism during checkpoint activation and the coordination of replication-transcription conflicts. In this review, I will highlight some of these new functions of Mec1/ATR with a focus on the yeast model organism.

Battery cycle life balancing in a microgrid through flexible distribution of energy and storage resources

NASA Astrophysics Data System (ADS)

Khasawneh, Hussam J.; Illindala, Mahesh S.

2014-09-01

In this paper, a microgrid consisting of four fuel cell-battery hybrid Distributed Energy Resources (DERs) is devised for an industrial crusher-conveyor load. Each fuel cell was accompanied by a Li-ion battery to provide energy storage support under islanded condition of the microgrid since the fuel cells typically have poor transient response characteristics. After carrying out extensive modeling and analysis in MATLAB®, the battery utilization was found to vary significantly based on the DER's 'electrical' placement within the microgrid. This paper presents, under such conditions, a variety of battery life balancing solutions through the use of the new framework of Flexible Distribution of EneRgy and Storage Resources (FDERS). It is based on an in-situ reconfiguration approach through 'virtual' reactances that help in changing the 'electrical' position of each DER without physically displacing any component in the system. Several possible approaches toward balancing the battery utilization are compared in this paper taking advantage of the flexibility that FDERS offers. It was observed that the estimated battery life is dependent on factors such as cycling sequence, pattern, and occurrence.

New Ether-functionalized Morpholinium- and Piperidinium-based Ionic Liquids as Electrolyte Components in Lithium and Lithium-Ion Batteries.

PubMed

Navarra, Maria Assunta; Fujimura, Kanae; Sgambetterra, Mirko; Tsurumaki, Akiko; Panero, Stefania; Nakamura, Nobuhumi; Ohno, Hiroyuki; Scrosati, Bruno

2017-06-09

Here, two ionic liquids, N-ethoxyethyl-N-methylmorpholinium bis(trifluoromethanesulfonyl)imide (M 1,2O2 TFSI) and N-ethoxyethyl-N-methylpiperidinium bis(trifluoromethanesulfonyl)imide (P 1,2O2 TFSI) were synthesized and compared. Fundamental relevant properties, such as thermal and electrochemical stability, density, and ionic conductivity were analyzed to evaluate the effects caused by the presence of the ether bond in the side chain and/or in the organic cation ring. Upon lithium salt addition, two electrolytes suitable for lithium batteries applications were found. Higher conducting properties of the piperidinium-based electrolyte resulted in enhanced cycling performances when tested with LiFePO 4 (LFP) cathode in lithium cells. When mixing the P 1,2O2 TFSI/LiTFSI electrolyte with a tailored alkyl carbonate mixture, the cycling performance of both Li and Li-ion cells greatly improved, with prolonged cyclability delivering very stable capacity values, as high as the theoretical one in the case of Li/LFP cell configurations. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Basal body assembly in ciliates: the power of numbers

PubMed Central

Pearson, Chad G.; Winey, Mark

2009-01-01

Centrioles perform the dual functions of organizing both centrosomes and cilia. The biogenesis of nascent centrioles is an essential cellular event that is tightly coupled to the cell cycle so that each cell contains only two or four centrioles at any given point in the cell cycle. The assembly of centrioles and their analogs, basal bodies, is well characterized at the ultrastructural level whereby structural modules are built into a functional organelle. Genetic studies in model organisms combined with proteomic, bioinformatic, and identifying ciliary disease gene orthologs have revealed a wealth of molecules requiring further analysis to determine their roles in centriole duplication, assembly, and function. Nonetheless, at this stage our understanding of how molecular components interact to build new centrioles and basal bodies is limited. The ciliates, Tetrahymena and Paramecium, historically have been the subject of cytological and genetic study of basal bodies. Recent advances in the ciliate genetic and molecular toolkit have placed these model organisms in a favorable position to study the molecular mechanisms of centriole and basal body assembly. PMID:19192246

Telomerase and Tel1p Preferentially Associate with Short Telomeres in S. cerevisiae

PubMed Central

Sabourin, Michelle; Tuzon, Creighton T.; Zakian, Virginia A.

2009-01-01

SUMMARY In diverse organisms, telomerase preferentially elongates short telomeres. We generated a single short telomere in otherwise wild-type (WT) S. cerevisiae cells. The binding of the positive regulators Ku and Cdc13p was similar at short and WT-length telomeres. The negative regulators Rif1p and Rif2p were present at the short telomere, although Rif2p levels were reduced. Two telomerase holoenzyme components, Est1p and Est2p, were preferentially enriched at short telomeres in late S/G2 phase, the time of telomerase action. Tel1p, the yeast ATM-like checkpoint kinase, was highly enriched at short telomeres from early S through G2 phase and even into the next cell cycle. Nonetheless, induction of a single short telomere did not elicit a cell-cycle arrest. Tel1p binding was dependent on Xrs2p and required for preferential binding of telomerase to short telomeres. These data suggest that Tel1p targets telomerase to the DNA ends most in need of extension. PMID:17656141

Suspended animation in C. elegans requires the spindle checkpoint.

PubMed

Nystul, Todd G; Goldmark, Jesse P; Padilla, Pamela A; Roth, Mark B

2003-11-07

In response to environmental signals such as anoxia, many organisms enter a state of suspended animation, an extreme form of quiescence in which microscopically visible movement ceases. We have identified a gene, san-1, that is required for suspended animation in Caenorhabditis elegans embryos. We show that san-1 functions as a spindle checkpoint component in C. elegans. During anoxia-induced suspended animation, embryos lacking functional SAN-1 or a second spindle checkpoint component, MDF-2, failed to arrest the cell cycle, exhibited chromosome missegregation, and showed reduced viability. These data provide a model for how a dynamic biological process is arrested in suspended animation.

Modelling cell cycle synchronisation in networks of coupled radial glial cells.

PubMed

Barrack, Duncan S; Thul, Rüdiger; Owen, Markus R

2015-07-21

Radial glial cells play a crucial role in the embryonic mammalian brain. Their proliferation is thought to be controlled, in part, by ATP mediated calcium signals. It has been hypothesised that these signals act to locally synchronise cell cycles, so that clusters of cells proliferate together, shedding daughter cells in uniform sheets. In this paper we investigate this cell cycle synchronisation by taking an ordinary differential equation model that couples the dynamics of intracellular calcium and the cell cycle and extend it to populations of cells coupled via extracellular ATP signals. Through bifurcation analysis we show that although ATP mediated calcium release can lead to cell cycle synchronisation, a number of other asynchronous oscillatory solutions including torus solutions dominate the parameter space and cell cycle synchronisation is far from guaranteed. Despite this, numerical results indicate that the transient and not the asymptotic behaviour of the system is important in accounting for cell cycle synchronisation. In particular, quiescent cells can be entrained on to the cell cycle via ATP mediated calcium signals initiated by a driving cell and crucially will cycle in near synchrony with the driving cell for the duration of neurogenesis. This behaviour is highly sensitive to the timing of ATP release, with release at the G1/S phase transition of the cell cycle far more likely to lead to near synchrony than release during mid G1 phase. This result, which suggests that ATP release timing is critical to radial glia cell cycle synchronisation, may help us to understand normal and pathological brain development. Copyright © 2015 Elsevier Ltd. All rights reserved.

Unraveling Interfaces between Energy Metabolism and Cell Cycle in Plants.

PubMed

Siqueira, João Antonio; Hardoim, Pablo; Ferreira, Paulo C G; Nunes-Nesi, Adriano; Hemerly, Adriana S

2018-06-19

Oscillation in energy levels is widely variable in dividing and differentiated cells. To synchronize cell proliferation and energy fluctuations, cell cycle-related proteins have been implicated in the regulation of mitochondrial energy-generating pathways in yeasts and animals. Plants have chloroplasts and mitochondria, coordinating the cell energy flow. Recent findings suggest an integrated regulation of these organelles and the nuclear cell cycle. Furthermore, reports indicate a set of interactions between the cell cycle and energy metabolism, coordinating the turnover of proteins in plants. Here, we discuss how cell cycle-related proteins directly interact with energy metabolism-related proteins to modulate energy homeostasis and cell cycle progression. We provide interfaces between cell cycle and energy metabolism-related proteins that could be explored to maximize plant yield. Copyright © 2018 Elsevier Ltd. All rights reserved.

Adenomatous Polyposis Coli-Mediated Accumulation of Abasic DNA Lesions Lead to Cigarette Smoke Condensate-Induced Neoplastic Transformation of Normal Breast Epithelial Cells1

PubMed Central

Jaiswal, Aruna S; Panda, Harekrushna; Pampo, Christine A; Siemann, Dietmar W; Gairola, C Gary; Hromas, Robert; Narayan, Satya

2013-01-01

Adenomatous polyposis coli (APC) is a multifunctional protein having diverse cellular functions including cell migration, cell-cell adhesion, cell cycle control, chromosomal segregation, and apoptosis. Recently, we found a new role of APC in base excision repair (BER) and showed that it interacts with DNA polymerase β and 5′-flap endonuclease 1 and interferes in BER. Previously, we have also reported that cigarette smoke condensate (CSC) increases expression of APC and enhances the growth of normal human breast epithelial (MCF10A) cells in vitro. In the present study, using APC overexpression and knockdown systems, we have examined the molecular mechanisms by which CSC and its major component, Benzo[α]pyrene, enhances APC-mediated accumulation of abasic DNA lesions, which is cytotoxic and mutagenic in nature, leading to enhanced neoplastic transformation of MCF10A cells in an orthotopic xenograft model. PMID:23555190

Cell cycle in ascidian eggs and embryos.

PubMed

McDougall, Alex; Chenevert, Janet; Lee, Karen W; Hebras, Celine; Dumollard, Remi

2011-01-01

In ascidians the cell cycle machinery has been studied mainly in oocytes while ascidian embryos have been used to dissect the mechanism that controls asymmetric cell division (ACD). Here we overview the most specific and often exceptional points and events in cell cycle control in ascidian oocytes and early embryos. Mature stage IV eggs are arrested at metaphase I due to cytostatic factor (CSF). In vertebrates, unfertilized eggs are arrested at metaphase II by CSF. Meta II-CSF is mediated by the Mos/MEK/MAPK/Erp1 pathway, which inhibits the ubiquitin ligase APC/C(cdc20) preventing cyclin B destruction thus stabilizing MPF activity. CSF is inactivated by the fertilization Ca(2+) transient that stimulates the destruction of Erp1 thus releasing APC/C(cdc20) from inhibition. Although many of the components of CSF are conserved between the ascidian and the vertebrates, the lack of Erp1 in the ascidians (and indeed other invertebrates) is notable since the Mos/MAPK pathway nonetheless mediates Meta I-CSF. Moreover, since the fertilization Ca(2+) transient targets Erp1, it is not clear how the sperm-triggered Ca(2+) transient in ascidians (and again other invertebrates) stimulates cyclin B destruction in the absence of Erp1. Nonetheless, like mammalian eggs, sperm trigger a series of Ca(2+) oscillations that increases the rate of cyclin B destruction and the subsequent loss of MAPK activity leading to meiotic exit in ascidians. Positive feedback from MPF maintains the Ca(2+) oscillations in fertilized ascidian eggs ensuring the eventual loss of MPF stimulating the egg-to-embryo transition. Embryonic cell cycles in the ascidian are highly stereotyped where both the rate of cell division and the orientation of cell division planes are precisely controlled. Three successive rounds of ACD generate two small posterior germ cell precursors at the 64 cell stage. The centrosome-attracting body (CAB) is a macroscopic cortical structure visible by light microscopy that causes these three rounds of ACD. Entry into mitosis activates the CAB causing the whole mitotic spindle to rotate and migrate toward the cortical CAB leading to a highly ACD whereby one small cell is formed that inherits the CAB and approximately 40 maternal postplasmic/PEM RNAs including the germ cell marker vasa.

A Role of hIPI3 in DNA Replication Licensing in Human Cells.

PubMed

Huang, Yining; Amin, Aftab; Qin, Yan; Wang, Ziyi; Jiang, Huadong; Liang, Lu; Shi, Linjing; Liang, Chun

2016-01-01

The yeast Ipi3p is required for DNA replication and cell viability in Sacharomyces cerevisiae. It is an essential component of the Rix1 complex (Rix1p/Ipi2p-Ipi1p-Ipi3p) that is required for the processing of 35S pre-rRNA in pre-60S ribosomal particles and for the initiation of DNA replication. The human IPI3 homolog is WDR18 (WD repeat domain 18), which shares significant homology with yIpi3p. Here we report that knockdown of hIPI3 resulted in substantial defects in the chromatin association of the MCM complex, DNA replication, cell cycle progression and cell proliferation. Importantly, hIPI3 silencing did not result in a reduction of the protein level of hCDC6, hMCM7, or the ectopically expressed GFP protein, indicating that protein synthesis was not defective in the same time frame of the DNA replication and cell cycle defects. Furthermore, the mRNA and protein levels of hIPI3 fluctuate in the cell cycle, with the highest levels from M phase to early G1 phase, similar to other pre-replicative (pre-RC) proteins. Moreover, hIPI3 interacts with other replication-initiation proteins, co-localizes with hMCM7 in the nucleus, and is important for the nuclear localization of hMCM7. We also found that hIPI3 preferentially binds to the origins of DNA replication including those at the c-Myc, Lamin-B2 and β-Globin loci. These results indicate that hIPI3 is involved in human DNA replication licensing independent of its role in ribosome biogenesis.

Coordination of Myeloid Differentiation with Reduced Cell Cycle Progression by PU.1 Induction of MicroRNAs Targeting Cell Cycle Regulators and Lipid Anabolism.

PubMed

Solomon, Lauren A; Podder, Shreya; He, Jessica; Jackson-Chornenki, Nicholas L; Gibson, Kristen; Ziliotto, Rachel G; Rhee, Jess; DeKoter, Rodney P

2017-05-15

During macrophage development, myeloid progenitor cells undergo terminal differentiation coordinated with reduced cell cycle progression. Differentiation of macrophages from myeloid progenitors is accompanied by increased expression of the E26 transformation-specific transcription factor PU.1. Reduced PU.1 expression leads to increased proliferation and impaired differentiation of myeloid progenitor cells. It is not understood how PU.1 coordinates macrophage differentiation with reduced cell cycle progression. In this study, we utilized cultured PU.1-inducible myeloid cells to perform genome-wide chromatin immunoprecipitation sequencing (ChIP-seq) analysis coupled with gene expression analysis to determine targets of PU.1 that may be involved in regulating cell cycle progression. We found that genes encoding cell cycle regulators and enzymes involved in lipid anabolism were directly and inducibly bound by PU.1 although their steady-state mRNA transcript levels were reduced. Inhibition of lipid anabolism was sufficient to reduce cell cycle progression in these cells. Induction of PU.1 reduced expression of E2f1 , an important activator of genes involved in cell cycle and lipid anabolism, indirectly through microRNA 223. Next-generation sequencing identified microRNAs validated as targeting cell cycle and lipid anabolism for downregulation. These results suggest that PU.1 coordinates cell cycle progression with differentiation through induction of microRNAs targeting cell cycle regulators and lipid anabolism. Copyright © 2017 American Society for Microbiology.

Cell cycle-related metabolism and mitochondrial dynamics in a replication-competent pancreatic beta-cell line.

PubMed

Montemurro, Chiara; Vadrevu, Suryakiran; Gurlo, Tatyana; Butler, Alexandra E; Vongbunyong, Kenny E; Petcherski, Anton; Shirihai, Orian S; Satin, Leslie S; Braas, Daniel; Butler, Peter C; Tudzarova, Slavica

2017-01-01

Cell replication is a fundamental attribute of growth and repair in multicellular organisms. Pancreatic beta-cells in adults rarely enter cell cycle, hindering the capacity for regeneration in diabetes. Efforts to drive beta-cells into cell cycle have so far largely focused on regulatory molecules such as cyclins and cyclin-dependent kinases (CDKs). Investigations in cancer biology have uncovered that adaptive changes in metabolism, the mitochondrial network, and cellular Ca 2+ are critical for permitting cells to progress through the cell cycle. Here, we investigated these parameters in the replication-competent beta-cell line INS 832/13. Cell cycle synchronization of this line permitted evaluation of cell metabolism, mitochondrial network, and cellular Ca 2+ compartmentalization at key cell cycle stages. The mitochondrial network is interconnected and filamentous at G1/S but fragments during the S and G2/M phases, presumably to permit sorting to daughter cells. Pyruvate anaplerosis peaks at G1/S, consistent with generation of biomass for daughter cells, whereas mitochondrial Ca 2+ and respiration increase during S and G2/M, consistent with increased energy requirements for DNA and lipid synthesis. This synchronization approach may be of value to investigators performing live cell imaging of Ca 2+ or mitochondrial dynamics commonly undertaken in INS cell lines because without synchrony widely disparate data from cell to cell would be expected depending on position within cell cycle. Our findings also offer insight into why replicating beta-cells are relatively nonfunctional secreting insulin in response to glucose. They also provide guidance on metabolic requirements of beta-cells for the transition through the cell cycle that may complement the efforts currently restricted to manipulating cell cycle to drive beta-cells through cell cycle.

A Short-Term Advantage for Syngamy in the Origin of Eukaryotic Sex: Effects of Cell Fusion on Cell Cycle Duration and Other Effects Related to the Duration of the Cell Cycle-Relationship between Cell Growth Curve and the Optimal Size of the Species, and Circadian Cell Cycle in Photosynthetic Unicellular Organisms.

PubMed

Mancebo Quintana, J M; Mancebo Quintana, S

2012-01-01

The origin of sex is becoming a vexatious issue for Evolutionary Biology. Numerous hypotheses have been proposed, based on the genetic effects of sex, on trophic effects or on the formation of cysts and syncytia. Our approach addresses the change in cell cycle duration which would cause cell fusion. Several results are obtained through graphical and mathematical analysis and computer simulations. (1) In poor environments, cell fusion would be an advantageous strategy, as fusion between cells of different size shortens the cycle of the smaller cell (relative to the asexual cycle), and the majority of mergers would occur between cells of different sizes. (2) The easiest-to-evolve regulation of cell proliferation (sexual/asexual) would be by modifying the checkpoints of the cell cycle. (3) A regulation of this kind would have required the existence of the G2 phase, and sex could thus be the cause of the appearance of this phase. Regarding cell cycle, (4) the exponential curve is the only cell growth curve that has no effect on the optimal cell size in unicellular species; (5) the existence of a plateau with no growth at the end of the cell cycle explains the circadian cell cycle observed in unicellular algae.

A balance of FGF and BMP signals regulates cell cycle exit and Equarin expression in lens cells

PubMed Central

Jarrin, Miguel; Pandit, Tanushree; Gunhaga, Lena

2012-01-01

In embryonic and adult lenses, a balance of cell proliferation, cell cycle exit, and differentiation is necessary to maintain physical function. The molecular mechanisms regulating the transition of proliferating lens epithelial cells to differentiated primary lens fiber cells are poorly characterized. To investigate this question, we used gain- and loss-of-function analyses to modulate fibroblast growth factor (FGF) and/or bone morphogenetic protein (BMP) signals in chick lens/retina explants. Here we show that FGF activity plays a key role for proliferation independent of BMP signals. Moreover, a balance of FGF and BMP signals regulates cell cycle exit and the expression of Ccdc80 (also called Equarin), which is expressed at sites where differentiation of lens fiber cells occurs. BMP activity promotes cell cycle exit and induces Equarin expression in an FGF-dependent manner. In contrast, FGF activity is required but not sufficient to induce cell cycle exit or Equarin expression. Furthermore, our results show that in the absence of BMP activity, lens cells have increased cell cycle length or are arrested in the cell cycle, which leads to decreased cell cycle exit. Taken together, these findings suggest that proliferation, cell cycle exit, and early differentiation of primary lens fiber cells are regulated by counterbalancing BMP and FGF signals. PMID:22718906

Transcription Factor Binding Profiles Reveal Cyclic Expression of Human Protein-coding Genes and Non-coding RNAs

PubMed Central

Cheng, Chao; Ung, Matthew; Grant, Gavin D.; Whitfield, Michael L.

2013-01-01

Cell cycle is a complex and highly supervised process that must proceed with regulatory precision to achieve successful cellular division. Despite the wide application, microarray time course experiments have several limitations in identifying cell cycle genes. We thus propose a computational model to predict human cell cycle genes based on transcription factor (TF) binding and regulatory motif information in their promoters. We utilize ENCODE ChIP-seq data and motif information as predictors to discriminate cell cycle against non-cell cycle genes. Our results show that both the trans- TF features and the cis- motif features are predictive of cell cycle genes, and a combination of the two types of features can further improve prediction accuracy. We apply our model to a complete list of GENCODE promoters to predict novel cell cycle driving promoters for both protein-coding genes and non-coding RNAs such as lincRNAs. We find that a similar percentage of lincRNAs are cell cycle regulated as protein-coding genes, suggesting the importance of non-coding RNAs in cell cycle division. The model we propose here provides not only a practical tool for identifying novel cell cycle genes with high accuracy, but also new insights on cell cycle regulation by TFs and cis-regulatory elements. PMID:23874175

Cycle life test and failure model of nickel-hydrogen cells

NASA Technical Reports Server (NTRS)

Smithrick, J. J.

1983-01-01

Six ampere hour individual pressure vessel nickel hydrogen cells were charge/discharge cycled to failure. Failure as used here is defined to occur when the end of discharge voltage degraded to 0.9 volts. They were cycled under a low earth orbit cycle regime to a deep depth of discharge (80 percent of rated ampere hour capacity). Both cell designs were fabricated by the same manufacturer and represent current state of the art. A failure model was advanced which suggests both cell designs have inadequate volume tolerance characteristics. The limited existing data base at a deep depth of discharge (DOD) was expanded. Two cells of each design were cycled. One COMSAT cell failed at cycle 1712 and the other failed at cycle 1875. For the Air Force/Hughes cells, one cell failed at cycle 2250 and the other failed at cycle 2638. All cells, of both designs, failed due to low end of discharge voltage (0.9 volts). No cell failed due to electrical shorts. After cell failure, three different reconditioning tests (deep discharge, physical reorientation, and open circuit voltage stand) were conducted on all cells of each design. A fourth reconditioning test (electrolyte addition) was conducted on one cell of each design. In addition post cycle cell teardown and failure analysis were performed on the one cell of each design which did not have electrolyte added after failure.

The acetate switch.

PubMed

Wolfe, Alan J

2005-03-01

To succeed, many cells must alternate between life-styles that permit rapid growth in the presence of abundant nutrients and ones that enhance survival in the absence of those nutrients. One such change in life-style, the "acetate switch," occurs as cells deplete their environment of acetate-producing carbon sources and begin to rely on their ability to scavenge for acetate. This review explains why, when, and how cells excrete or dissimilate acetate. The central components of the "switch" (phosphotransacetylase [PTA], acetate kinase [ACK], and AMP-forming acetyl coenzyme A synthetase [AMP-ACS]) and the behavior of cells that lack these components are introduced. Acetyl phosphate (acetyl approximately P), the high-energy intermediate of acetate dissimilation, is discussed, and conditions that influence its intracellular concentration are described. Evidence is provided that acetyl approximately P influences cellular processes from organelle biogenesis to cell cycle regulation and from biofilm development to pathogenesis. The merits of each mechanism proposed to explain the interaction of acetyl approximately P with two-component signal transduction pathways are addressed. A short list of enzymes that generate acetyl approximately P by PTA-ACKA-independent mechanisms is introduced and discussed briefly. Attention is then directed to the mechanisms used by cells to "flip the switch," the induction and activation of the acetate-scavenging AMP-ACS. First, evidence is presented that nucleoid proteins orchestrate a progression of distinct nucleoprotein complexes to ensure proper transcription of its gene. Next, the way in which cells regulate AMP-ACS activity through reversible acetylation is described. Finally, the "acetate switch" as it exists in selected eubacteria, archaea, and eukaryotes, including humans, is described.

Comparing contractile apparatus-driven cytokinesis mechanisms across kingdoms.

PubMed

Balasubramanian, Mohan K; Srinivasan, Ramanujam; Huang, Yinyi; Ng, Kian-Hong

2012-11-01

Cytokinesis is the final stage of the cell cycle during which a cell physically divides into two daughters through the assembly of new membranes (and cell wall in some cases) between the forming daughters. New membrane assembly can either proceed centripetally behind a contractile apparatus, as in the case of prokaryotes, archaea, fungi, and animals or expand centrifugally, as in the case of higher plants. In this article, we compare the mechanisms of cytokinesis in diverse organisms dividing through the use of a contractile apparatus. While an actomyosin ring participates in cytokinesis in almost all centripetally dividing eukaryotes, the majority of bacteria and archaea (except Crenarchaea) divide using a ring composed of the tubulin-related protein FtsZ. Curiously, despite molecular conservation of the division machinery components, division site placement and its cell cycle regulation occur by a variety of unrelated mechanisms even among organisms from the same kingdom. While molecular motors and cytoskeletal polymer dynamics contribute to force generation during eukaryotic cytokinesis, cytoskeletal polymer dynamics alone appears to be sufficient for force generation during prokaryotic cytokinesis. Intriguingly, there are life forms on this planet that appear to lack molecules currently known to participate in cytokinesis and how these cells perform cytokinesis remains a mystery waiting to be unravelled. Copyright © 2012 Wiley Periodicals, Inc.

2′,4′-dihydroxychalcone, a flavonoid isolated from Herba oxytropis, suppresses PC-3 human prostate cancer cell growth by induction of apoptosis

PubMed Central

SHENG, YUQING; ZOU, MINGCHANG; WANG, YAN; LI, QIHENG

2015-01-01

Natural products are a promising source for the development of novel cancer therapies, due to their potential effectiveness and low toxicity profiles. As a main component of Herba oxytropis, 2′,4′-dihydroxychalcone (TFC) is known to demonstrate anti-tumor activity in vitro. In the present study, TFC was found to potently inhibit proliferation and induce apoptosis in PC-3 human prostate cancer cells in a dose-dependent manner. The results demonstrated that the induction of apoptosis is associated with cell cycle arrest at the G0/G1 phase and activation of caspase-3/-7. Additional mechanistic studies of two biomarkers, phosphatase and tensin homolog (PTEN) and cyclin-dependent kinase inhibitor 1B (p27Kip1), in prostate cancer revealed that TFC treatment significantly upregulated the expression of PTEN and p27Kip1. The findings of the present study indicate that TFC-induced apoptosis in PC-3 cells via upregulation of PTEN and p27Kip1, which results in cell cycle arrest in G0/G1 phase, activation of caspase-3/-7 and induction of apoptosis. Therefore, TFC may be a potential compound for human prostate cancer therapy. PMID:26788200

Atorvastatin Downregulates In Vitro Methyl Methanesulfonate and Cyclophosphamide Alkylation-Mediated Cellular and DNA Injuries

PubMed Central

Christoni, Larissa S. A.; Justo, Graça; Soeiro, Maria N. C.

2018-01-01

Statins are 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors, and this class of drugs has been studied as protective agents against DNA damages. Alkylating agents (AAs) are able to induce alkylation in macromolecules, causing DNA damage, as DNA methylation. Our objective was to evaluate atorvastatin (AVA) antimutagenic, cytoprotective, and antigenotoxic potentials against DNA lesions caused by AA. AVA chemopreventive ability was evaluated using antimutagenicity assays (Salmonella/microsome assay), cytotoxicity, cell cycle, and genotoxicity assays in HepG2 cells. The cells were cotreated with AVA and the AA methyl methanesulfonate (MMS) or cyclophosphamide (CPA). Our datum showed that AVA reduces the alkylation-mediated DNA damage in different in vitro experimental models. Cytoprotection of AVA at low doses (0.1–1.0 μM) was observed after 24 h of cotreatment with MMS or CPA at their LC50, causing an increase in HepG2 survival rates. After all, AVA at 10 μM and 25 μM had decreased effect in micronucleus formation in HepG2 cells and restored cell cycle alterations induced by MMS and CPA. This study supports the hypothesis that statins can be chemopreventive agents, acting as antimutagenic, antigenotoxic, and cytoprotective components, specifically against alkylating agents of DNA. PMID:29849914

Ziyuglycoside I Inhibits the Proliferation of MDA-MB-231 Breast Carcinoma Cells through Inducing p53-Mediated G2/M Cell Cycle Arrest and Intrinsic/Extrinsic Apoptosis.

PubMed

Zhu, Xue; Wang, Ke; Zhang, Kai; Zhang, Ting; Yin, Yongxiang; Xu, Fei

2016-11-22

Due to the aggressive clinical behavior, poor outcome, and lack of effective specific targeted therapies, triple-negative breast cancer (TNBC) has currently been recognized as one of the most malignant types of tumors. In the present study, we investigated the cytotoxic effect of ziyuglycoside I, one of the major components extracted from Chinese anti-tumor herbal Radix Sanguisorbae , on the TNBC cell line MDA-MB-231. The underlying molecular mechanism of the cytotoxic effect ziyuglycoside I on MDA-MB-231 cells was investigated with cell viability assay, flow cytometric analysis and Western blot. Compared to normal mammary gland Hs 578Bst cells, treatment of ziyuglycoside I resulted in a significant growth inhibitory effect on MDA-MB-231 cells. Ziyuglycoside I induced the G2/M phase arrest and apoptosis of MDA-MB-231 cells in a dose-dependent manner. These effects were found to be partially mediated through the up-regulation of p53 and p21 WAF1 , elevated Bax/Bcl-2 ratio, and the activation of both intrinsic (mitochondrial-initiated) and extrinsic (Fas/FasL-initiated) apoptotic pathways. Furthermore, the p53 specific siRNA attenuated these effects. Our study suggested that ziyuglycoside I-triggered MDA-MB-231 cell cycle arrest and apoptosis were probably mediated by p53. This suggests that ziyuglycoside I might be a potential drug candidate for treating TNBC.

Cell Cycle Control by PTEN.

PubMed

Brandmaier, Andrew; Hou, Sheng-Qi; Shen, Wen H

2017-07-21

Continuous and error-free chromosome inheritance through the cell cycle is essential for genomic stability and tumor suppression. However, accumulation of aberrant genetic materials often causes the cell cycle to go awry, leading to malignant transformation. In response to genotoxic stress, cells employ diverse adaptive mechanisms to halt or exit the cell cycle temporarily or permanently. The intrinsic machinery of cycling, resting, and exiting shapes the cellular response to extrinsic stimuli, whereas prevalent disruption of the cell cycle machinery in tumor cells often confers resistance to anticancer therapy. Phosphatase and tensin homolog (PTEN) is a tumor suppressor and a guardian of the genome that is frequently mutated or deleted in human cancer. Moreover, it is increasingly evident that PTEN deficiency disrupts the fundamental processes of genetic transmission. Cells lacking PTEN exhibit cell cycle deregulation and cell fate reprogramming. Here, we review the role of PTEN in regulating the key processes in and out of cell cycle to optimize genomic integrity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Nestin suppression attenuates invasive potential of endometrial cancer cells by downregulating TGF-β signaling pathway.

PubMed

Bokhari, Amber A; Baker, Tabari M; Dorjbal, Batsukh; Waheed, Sana; Zahn, Christopher M; Hamilton, Chad A; Maxwell, G Larry; Syed, Viqar

2016-10-25

Nestin, an intermediate filament protein and a stem cell marker is expressed in several tumors. Until recently, little was known about the expression levels and the role of Nestin in endometrial cancer. Compared to the immortalized endometrial epithelial cell line EM-E6/E7-TERT, endometrial cancer cell lines express high to moderate levels of Nestin. Furthermore, endometrial tumors and tumor cell lines have a cancer stem-like cell subpopulation expressing CD133. Among the cancer lines, AN3CA and KLE cells exhibited both a significantly higher number of CD133+ cells and expressed Nestin at higher levels than Ishikawa cells. Knockdown of Nestin in AN3CA and KLE increased cells in G0/G1 phase of the cell cycle, whereas overexpression in Ishikawa decreased cells in G0/G1 phase and increased cells in S-phase. Nestin knockdown cells showed increased p21, p27, and PNCA levels and decreased expression of cyclin-D1 and D3. In contrast, Nestin overexpression revealed an inverse expression pattern of cell cycle regulatory proteins. Nestin knockdown inhibited cancer cell growth and invasive potential by downregulating TGF-β signaling components, MMP-2, MMP-9, vimentin, SNAIL, SLUG, Twist, N-cadherin, and upregulating the epithelial cell marker E-cadherin whereas the opposite was observed with Nestin overexpressing Ishikawa cells. Nestin knockdown also inhibited, while overexpression promoted invadopodia formation and pFAK expression. Knockdown of Nestin significantly reduced tumor volume in vivo. Finally, progesterone inhibited Nestin expression in endometrial cancer cells. These results suggest that Nestin can be a therapeutic target for cancer treatment.

Nestin suppression attenuates invasive potential of endometrial cancer cells by downregulating TGF-β signaling pathway

PubMed Central

Bokhari, Amber A.; Baker, Tabari M.; Dorjbal, Batsukh; Waheed, Sana; Zahn, Christopher M.; Hamilton, Chad A.; Maxwell, G. Larry; Syed, Viqar

2016-01-01

Nestin, an intermediate filament protein and a stem cell marker is expressed in several tumors. Until recently, little was known about the expression levels and the role of Nestin in endometrial cancer. Compared to the immortalized endometrial epithelial cell line EM-E6/E7-TERT, endometrial cancer cell lines express high to moderate levels of Nestin. Furthermore, endometrial tumors and tumor cell lines have a cancer stem-like cell subpopulation expressing CD133. Among the cancer lines, AN3CA and KLE cells exhibited both a significantly higher number of CD133+ cells and expressed Nestin at higher levels than Ishikawa cells. Knockdown of Nestin in AN3CA and KLE increased cells in G0/G1 phase of the cell cycle, whereas overexpression in Ishikawa decreased cells in G0/G1 phase and increased cells in S-phase. Nestin knockdown cells showed increased p21, p27, and PNCA levels and decreased expression of cyclin-D1 and D3. In contrast, Nestin overexpression revealed an inverse expression pattern of cell cycle regulatory proteins. Nestin knockdown inhibited cancer cell growth and invasive potential by downregulating TGF-β signaling components, MMP-2, MMP-9, vimentin, SNAIL, SLUG, Twist, N-cadherin, and upregulating the epithelial cell marker E-cadherin whereas the opposite was observed with Nestin overexpressing Ishikawa cells. Nestin knockdown also inhibited, while overexpression promoted invadopodia formation and pFAK expression. Knockdown of Nestin significantly reduced tumor volume in vivo. Finally, progesterone inhibited Nestin expression in endometrial cancer cells. These results suggest that Nestin can be a therapeutic target for cancer treatment. PMID:27626172

A Nonribosomal Landscape in the Nucleolus Revealed by the Stem Cell Protein Nucleostemin

PubMed Central

Politz, Joan C. Ritland; Polena, Ilvin; Trask, Ian; Bazett-Jones, David P.; Pederson, Thoru

2005-01-01

Nucleostemin is a p53-interactive cell cycle progression factor that shuttles between the nucleolus and nucleoplasm, but it has no known involvement in ribosome synthesis. We found the dynamic properties of nucleostemin differed strikingly from fibrillarin (a protein directly involved in rRNA processing) both in response to rRNA transcription inhibition and in the schedule of reentry into daughter nuclei and the nucleolus during late telophase/early G1. Furthermore, nucleostemin was excluded from the nucleolar domains in which ribosomes are born—the fibrillar centers and dense fibrillar component. Instead it was concentrated in rRNA-deficient sites within the nucleolar granular component. This finding suggests that the nucleolus may be more subcompartmentalized than previously thought. In support of this concept, electron spectroscopic imaging studies of the nitrogen and phosphorus distribution in the nucleolar granular component revealed regions that are very rich in protein and yet devoid of nucleic acid. Together, these results suggest that the ultrastructural texture of the nucleolar granular component represents not only ribosomal particles but also RNA-free zones populated by proteins or protein complexes that likely serve other functions. PMID:15857956

A Genome-Wide RNAi Screen for Modifiers of the Circadian Clock in Human Cells

PubMed Central

Zhang, Eric E.; Liu, Andrew C.; Hirota, Tsuyoshi; Miraglia, Loren J.; Welch, Genevieve; Pongsawakul, Pagkapol Y.; Liu, Xianzhong; Atwood, Ann; Huss, Jon W.; Janes, Jeff; Su, Andrew I.; Hogenesch, John B.; Kay, Steve A.

2009-01-01

Summary Two decades of research identified more than a dozen clock genes and defined a biochemical feedback mechanism of circadian oscillator function. To identify additional clock genes and modifiers, we conducted a genome-wide siRNA screen in a human cellular clock model. Knockdown of nearly a thousand genes reduced rhythm amplitude. Potent effects on period length or increased amplitude were less frequent; we found hundreds of these and confirmed them in secondary screens. Characterization of a subset of these genes demonstrated a dosage-dependent effect on oscillator function. Protein interaction network analysis showed that dozens of gene products directly or indirectly associate with known clock components. Pathway analysis revealed these genes are overrepresented for components of insulin and hedgehog signaling, the cell cycle, and the folate metabolism. Coupled with data showing many of these pathways are clock-regulated, we conclude the clock is interconnected with many aspects of cellular function. PMID:19765810

The therapeutic potential of cell cycle targeting in multiple myeloma.

PubMed

Maes, Anke; Menu, Eline; Veirman, Kim De; Maes, Ken; Vand Erkerken, Karin; De Bruyne, Elke

2017-10-27

Proper cell cycle progression through the interphase and mitosis is regulated by coordinated activation of important cell cycle proteins (including cyclin-dependent kinases and mitotic kinases) and several checkpoint pathways. Aberrant activity of these cell cycle proteins and checkpoint pathways results in deregulation of cell cycle progression, which is one of the key hallmarks of cancer. Consequently, intensive research on targeting these cell cycle regulatory proteins identified several candidate small molecule inhibitors that are able to induce cell cycle arrest and even apoptosis in cancer cells. Importantly, several of these cell cycle regulatory proteins have also been proposed as therapeutic targets in the plasma cell malignancy multiple myeloma (MM). Despite the enormous progress in the treatment of MM the past 5 years, MM still remains most often incurable due to the development of drug resistance. Deregulated expression of the cyclins D is observed in virtually all myeloma patients, emphasizing the potential therapeutic interest of cyclin-dependent kinase inhibitors in MM. Furthermore, other targets have also been identified in MM, such as microtubules, kinesin motor proteins, aurora kinases, polo-like kinases and the anaphase promoting complex/cyclosome. This review will provide an overview of the cell cycle proteins and checkpoint pathways deregulated in MM and discuss the therapeutic potential of targeting proteins or protein complexes involved in cell cycle control in MM.

An Off-Lattice Hybrid Discrete-Continuum Model of Tumor Growth and Invasion

PubMed Central

Jeon, Junhwan; Quaranta, Vito; Cummings, Peter T.

2010-01-01

Abstract We have developed an off-lattice hybrid discrete-continuum (OLHDC) model of tumor growth and invasion. The continuum part of the OLHDC model describes microenvironmental components such as matrix-degrading enzymes, nutrients or oxygen, and extracellular matrix (ECM) concentrations, whereas the discrete portion represents individual cell behavior such as cell cycle, cell-cell, and cell-ECM interactions and cell motility by the often-used persistent random walk, which can be depicted by the Langevin equation. Using this framework of the OLHDC model, we develop a phenomenologically realistic and bio/physically relevant model that encompasses the experimentally observed superdiffusive behavior (at short times) of mammalian cells. When systemic simulations based on the OLHDC model are performed, tumor growth and its morphology are found to be strongly affected by cell-cell adhesion and haptotaxis. There is a combination of the strength of cell-cell adhesion and haptotaxis in which fingerlike shapes, characteristic of invasive tumor, are observed. PMID:20074513

Rapid cell-free forward engineering of novel genetic ring oscillators

PubMed Central

Niederholtmeyer, Henrike; Sun, Zachary Z; Hori, Yutaka; Yeung, Enoch; Verpoorte, Amanda; Murray, Richard M; Maerkl, Sebastian J

2015-01-01

While complex dynamic biological networks control gene expression in all living organisms, the forward engineering of comparable synthetic networks remains challenging. The current paradigm of characterizing synthetic networks in cells results in lengthy design-build-test cycles, minimal data collection, and poor quantitative characterization. Cell-free systems are appealing alternative environments, but it remains questionable whether biological networks behave similarly in cell-free systems and in cells. We characterized in a cell-free system the ‘repressilator’, a three-node synthetic oscillator. We then engineered novel three, four, and five-gene ring architectures, from characterization of circuit components to rapid analysis of complete networks. When implemented in cells, our novel 3-node networks produced population-wide oscillations and 95% of 5-node oscillator cells oscillated for up to 72 hr. Oscillation periods in cells matched the cell-free system results for all networks tested. An alternate forward engineering paradigm using cell-free systems can thus accurately capture cellular behavior. DOI: http://dx.doi.org/10.7554/eLife.09771.001 PMID:26430766

NASA Lewis advanced IPV nickel-hydrogen technology

NASA Technical Reports Server (NTRS)

Smithrick, John J.; Britton, Doris L.

1993-01-01

Individual pressure vessel (IPV) nickel-hydrogen technology was advanced at NASA Lewis and under Lewis contracts. Some of the advancements are as follows: to use 26 percent potassium hydroxide electrolyte to improve cycle life and performance, to modify the state of the art cell design to eliminate identified failure modes and further improve cycle life, and to develop a lightweight nickel electrode to reduce battery mass, hence reduce launch and/or increase satellite payload. A breakthrough in the LEO cycle life of individual pressure vessel nickel-hydrogen battery cells was reported. The cycle life of boiler plate cells containing 26 percent KOH electrolyte was about 40,000 accelerated LEO cycles at 80 percent DOD compared to 3,500 cycles for cells containing 31 percent KOH. Results of the boiler plate cell tests have been validated at NWSC, Crane, Indiana. Forty-eight ampere-hour flight cells containing 26 and 31 percent KOH have undergone real time LEO cycle life testing at an 80 percent DOD, 10 C. The three cells containing 26 percent KOH failed on the average at cycle 19,500. The three cells containing 31 percent KOH failed on the average at cycle 6,400. Validation testing of NASA Lewis 125 Ah advanced design IPV nickel-hydrogen flight cells is also being conducted at NWSC, Crane, Indiana under a NASA Lewis contract. This consists of characterization, storage, and cycle life testing. There was no capacity degradation after 52 days of storage with the cells in the discharged state, on open circuit, 0 C, and a hydrogen pressure of 14.5 psia. The catalyzed wall wick cells have been cycled for over 22,694 cycles with no cell failures in the continuing test. All three of the non-catalyzed wall wick cells failed (cycles 9,588; 13,900; and 20,575). Cycle life test results of the Fibrex nickel electrode has demonstrated the feasibility of an improved nickel electrode giving a higher specific energy nickel-hydrogen cell. A nickel-hydrogen boiler plate cell using an 80 mil thick, 90 percent porous Fibrex nickel electrode has been cycled for 10,000 cycles at 40 percent DOD.

Functional compartmentalization of Rad9 and Hus1 reveals diverse assembly of the 9‐1‐1 complex components during the DNA damage response in Leishmania

PubMed Central

Damasceno, Jeziel D.; Obonaga, Ricardo; Santos, Elaine V.; Scott, Alan; McCulloch, Richard

2016-01-01

Summary The Rad9‐Rad1‐Hus1 (9‐1‐1) complex is a key component in the coordination of DNA damage sensing, cell cycle progression and DNA repair pathways in eukaryotic cells. This PCNA‐related trimer is loaded onto RPA‐coated single stranded DNA and interacts with ATR kinase to mediate effective checkpoint signaling to halt the cell cycle and to promote DNA repair. Beyond these core activities, mounting evidence suggests that a broader range of functions can be provided by 9‐1‐1 structural diversification. The protozoan parasite Leishmania is an early‐branching eukaryote with a remarkably plastic genome, which hints at peculiar genome maintenance mechanisms. Here, we investigated the existence of homologs of the 9‐1‐1 complex subunits in L. major and found that LmRad9 and LmRad1 associate with chromatin in response to replication stress and form a complex in vivo with LmHus1. Similar to LmHus1, LmRad9 participates in telomere homeostasis and in the response to both replication stress and double strand breaks. However, LmRad9 and LmHus1‐deficient cells present markedly opposite phenotypes, which suggest their functional compartmentalization. We show that some of the cellular pool of LmRad9 forms an alternative complex and that some of LmHus1 exists as a monomer. We propose that the diverse assembly of the Leishmania 9‐1‐1 subunits mediates functional compartmentalization, which has a direct impact on the response to genotoxic stress. PMID:27301589

Effect of cycling on the lithium/electrolyte interface in organic electrolytes

NASA Technical Reports Server (NTRS)

Surampudi, S.; Shen, D. H.; Huang, C.-K.; Narayanan, S. R.; Attia, A.; Halpert, G.; Peled, E.

1993-01-01

Nondestructive methods such as ac impedance spectroscopy and microcalorimetry are used to study the effect of cell cycling on the lithium/electrolyte interface. The reactivity of both uncycled and cycled lithium towards various electrolytes is examined by measuring the heat evolved from the cells under open-circuit conditions at 25 C by microcalorimetry. Cycled cells at the end of charge/discharge exhibited considerably higher heat output compared with the uncycled cells. After 30 d of storage, the heat output of the cycled cells is similar to that of the uncycled cells. The cell internal resistance increases with cycling, and this is attributed to the degradation of the electrolyte with cycling.

Evolution of complexity in the volvocine algae: transitions in individuality through Darwin's eye.

PubMed

Herron, Matthew D; Michod, Richard E

2008-02-01

The transition from unicellular to differentiated multicellular organisms constitutes an increase in the level complexity, because previously existing individuals are combined to form a new, higher-level individual. The volvocine algae represent a unique opportunity to study this transition because they diverged relatively recently from unicellular relatives and because extant species display a range of intermediate grades between unicellular and multicellular, with functional specialization of cells. Following the approach Darwin used to understand "organs of extreme perfection" such as the vertebrate eye, this jump in complexity can be reduced to a series of small steps that cumulatively describe a gradual transition between the two levels. We use phylogenetic reconstructions of ancestral character states to trace the evolution of steps involved in this transition in volvocine algae. The history of these characters includes several well-supported instances of multiple origins and reversals. The inferred changes can be understood as components of cooperation-conflict-conflict mediation cycles as predicted by multilevel selection theory. One such cycle may have taken place early in volvocine evolution, leading to the highly integrated colonies seen in extant volvocine algae. A second cycle, in which the defection of somatic cells must be prevented, may still be in progress.

SPS Energy Conversion Power Management Workshop

NASA Technical Reports Server (NTRS)

1980-01-01

Energy technology concerning photovoltaic conversion, solar thermal conversion systems, and electrical power distribution processing is discussed. The manufacturing processes involving solar cells and solar array production are summarized. Resource issues concerning gallium arsenides and silicon alternatives are reported. Collector structures for solar construction are described and estimates in their service life, failure rates, and capabilities are presented. Theories of advanced thermal power cycles are summarized. Power distribution system configurations and processing components are presented.

Cobalt doped lanthanum chromite material suitable for high temperature use

DOEpatents

Ruka, Roswell J.

1986-01-01

A high temperature, solid electrolyte electrochemical cell, subject to thermal cycling temperatures of between about 25.degree. C. and about 1200.degree. C., capable of electronic interconnection to at least one other electrochemical cell and capable of operating in an environment containing oxygen and a fuel, is made; where the cell has a first and second electrode with solid electrolyte between them, where an improved interconnect material is applied along a portion of a supporting electrode; where the interconnect is made of a chemically modified lanthanum chromite, containing cobalt as the important additive, which interconnect allows for adjustment of the thermal expansion of the interconnect material to more nearly match that of other cell components, such as zirconia electrolyte, and is stable in oxygen containing atmospheres such as air and in fuel environments.

Temporal fluxomics reveals oscillations in TCA cycle flux throughout the mammalian cell cycle.

PubMed

Ahn, Eunyong; Kumar, Praveen; Mukha, Dzmitry; Tzur, Amit; Shlomi, Tomer

2017-11-06

Cellular metabolic demands change throughout the cell cycle. Nevertheless, a characterization of how metabolic fluxes adapt to the changing demands throughout the cell cycle is lacking. Here, we developed a temporal-fluxomics approach to derive a comprehensive and quantitative view of alterations in metabolic fluxes throughout the mammalian cell cycle. This is achieved by combining pulse-chase LC-MS-based isotope tracing in synchronized cell populations with computational deconvolution and metabolic flux modeling. We find that TCA cycle fluxes are rewired as cells progress through the cell cycle with complementary oscillations of glucose versus glutamine-derived fluxes: Oxidation of glucose-derived flux peaks in late G1 phase, while oxidative and reductive glutamine metabolism dominates S phase. These complementary flux oscillations maintain a constant production rate of reducing equivalents and oxidative phosphorylation flux throughout the cell cycle. The shift from glucose to glutamine oxidation in S phase plays an important role in cell cycle progression and cell proliferation. © 2017 The Authors. Published under the terms of the CC BY 4.0 license.

Playing with the cell cycle to build the spinal cord.

PubMed

Molina, Angie; Pituello, Fabienne

2017-12-01

A fundamental issue in nervous system development and homeostasis is to understand the mechanisms governing the balance between the maintenance of proliferating progenitors versus their differentiation into post-mitotic neurons. Accumulating data suggest that the cell cycle and core regulators of the cell cycle machinery play a major role in regulating this fine balance. Here, we focus on the interplay between the cell cycle and cellular and molecular events governing spinal cord development. We describe the existing links between the cell cycle and interkinetic nuclear migration (INM). We show how the different morphogens patterning the neural tube also regulate the cell cycle machinery to coordinate proliferation and patterning. We give examples of how cell cycle core regulators regulate transcriptionally, or post-transcriptionally, genes involved in controlling the maintenance versus the differentiation of neural progenitors. Finally, we describe the changes in cell cycle kinetics occurring during neural tube patterning and at the time of neuronal differentiation, and we discuss future research directions to better understand the role of the cell cycle in cell fate decisions. Copyright © 2017 Elsevier Inc. All rights reserved.

Cell cycle proteins as promising targets in cancer therapy.

PubMed

Otto, Tobias; Sicinski, Piotr

2017-01-27

Cancer is characterized by uncontrolled tumour cell proliferation resulting from aberrant activity of various cell cycle proteins. Therefore, cell cycle regulators are considered attractive targets in cancer therapy. Intriguingly, animal models demonstrate that some of these proteins are not essential for proliferation of non-transformed cells and development of most tissues. By contrast, many cancers are uniquely dependent on these proteins and hence are selectively sensitive to their inhibition. After decades of research on the physiological functions of cell cycle proteins and their relevance for cancer, this knowledge recently translated into the first approved cancer therapeutic targeting of a direct regulator of the cell cycle. In this Review, we focus on proteins that directly regulate cell cycle progression (such as cyclin-dependent kinases (CDKs)), as well as checkpoint kinases, Aurora kinases and Polo-like kinases (PLKs). We discuss the role of cell cycle proteins in cancer, the rationale for targeting them in cancer treatment and results of clinical trials, as well as the future therapeutic potential of various cell cycle inhibitors.

The clock is ticking. Ageing of the circadian system: From physiology to cell cycle.

PubMed

Terzibasi-Tozzini, Eva; Martinez-Nicolas, Antonio; Lucas-Sánchez, Alejandro

2017-10-01

The circadian system is the responsible to organise the internal temporal order in relation to the environment of every process of the organisms producing the circadian rhythms. These rhythms have a fixed phase relationship among them and with the environment in order to optimise the available energy and resources. From a cellular level, circadian rhythms are controlled by genetic positive and negative auto-regulated transcriptional and translational feedback loops, which generate 24h rhythms in mRNA and protein levels of the clock components. It has been described about 10% of the genome is controlled by clock genes, with special relevance, due to its implications, to the cell cycle. Ageing is a deleterious process which affects all the organisms' structures including circadian system. The circadian system's ageing may produce a disorganisation among the circadian rhythms, arrhythmicity and, even, disconnection from the environment, resulting in a detrimental situation to the organism. In addition, some environmental conditions can produce circadian disruption, also called chronodisruption, which may produce many pathologies including accelerated ageing. Finally, some strategies to prevent, palliate or counteract chronodisruption effects have been proposed to enhance the circadian system, also called chronoenhancement. This review tries to gather recent advances in the chronobiology of the ageing process, including cell cycle, neurogenesis process and physiology. Copyright © 2017 Elsevier Ltd. All rights reserved.

Ionic liquids and oligomer electrolytes based on the B(CN)4(-) anion; ion association, physical and electrochemical properties.

PubMed

Scheers, Johan; Pitawala, Jagath; Thebault, Frederic; Kim, Jae-Kwang; Ahn, Jou-Hyeon; Matic, Aleksandar; Johansson, Patrik; Jacobsson, Per

2011-09-07

The role of B(CN)(4)(-) (Bison) as a component of battery electrolytes is addressed by investigating the ionic conductivity and phase behaviour of ionic liquids (ILs), ion association mechanisms, and the electrochemical stability and cycling properties of LiBison based electrochemical cells. For C(4)mpyrBison and C(2)mimBison ILs, and mixtures thereof, high ionic conductivities (3.4 ≤σ(ion)≤ 18 mS cm(-1)) are measured, which together with the glass transition temperatures (-80 ≤T(g)≤-76 °C) are found to shift systematically for most compositions. Unfortunately, poor solubility of LiBison in these ILs hinders their use as solvents for lithium salts, although good NaBison solubility offers an alternative application in Na(+) conducting electrolytes. The poor IL solubility of LiBison is predicted to be a result of a preferred monodentate ion association, according to first principles modelling, supported by Raman spectroscopy. The solubility is much improved in strongly Li(+) coordinating oligomers, for example polyethylene glycol dimethyl ether (PEGDME), with the practical performance tested in electrochemical cells. The electrolyte is found to be stable in Li/LiFePO(4) coin cells up to 4 V vs. Li and shows promising cycling performance, with a capacity retention of 99% over 22 cycles. This journal is © the Owner Societies 2011

Cell cycle nucleic acids, polypeptides and uses thereof

DOEpatents

Gordon-Kamm, William J [Urbandale, IA; Lowe, Keith S [Johnston, IA; Larkins, Brian A [Tucson, AZ; Dilkes, Brian R [Tucson, AZ; Sun, Yuejin [Westfield, IN

2007-08-14

The invention provides isolated nucleic acids and their encoded proteins that are involved in cell cycle regulation. The invention further provides recombinant expression cassettes, host cells, transgenic plants, and antibody compositions. The present invention provides methods and compositions relating to altering cell cycle protein content, cell cycle progression, cell number and/or composition of plants.

Quantitative Cell Cycle Analysis Based on an Endogenous All-in-One Reporter for Cell Tracking and Classification.

PubMed

Zerjatke, Thomas; Gak, Igor A; Kirova, Dilyana; Fuhrmann, Markus; Daniel, Katrin; Gonciarz, Magdalena; Müller, Doris; Glauche, Ingmar; Mansfeld, Jörg

2017-05-30

Cell cycle kinetics are crucial to cell fate decisions. Although live imaging has provided extensive insights into this relationship at the single-cell level, the limited number of fluorescent markers that can be used in a single experiment has hindered efforts to link the dynamics of individual proteins responsible for decision making directly to cell cycle progression. Here, we present fluorescently tagged endogenous proliferating cell nuclear antigen (PCNA) as an all-in-one cell cycle reporter that allows simultaneous analysis of cell cycle progression, including the transition into quiescence, and the dynamics of individual fate determinants. We also provide an image analysis pipeline for automated segmentation, tracking, and classification of all cell cycle phases. Combining the all-in-one reporter with labeled endogenous cyclin D1 and p21 as prime examples of cell-cycle-regulated fate determinants, we show how cell cycle and quantitative protein dynamics can be simultaneously extracted to gain insights into G1 phase regulation and responses to perturbations. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

Interplay between cancer cell cycle and metabolism: Challenges, targets and therapeutic opportunities.

PubMed

Roy, Debmalya; Sheng, Gao Ying; Herve, Semukunzi; Carvalho, Evandro; Mahanty, Arpan; Yuan, Shengtao; Sun, Li

2017-05-01

A growing interest has emerged in the field of studying the cross-talk between cancer cell cycle and metabolism. In this review, we aimed to present how metabolism and cell cycle are correlated and how cancer cells get energy to drive cell cycle. Cell proliferation and cell death largely depend on the metabolic activity of the cell. Cell cycle proteins, e.g. cyclin D, cyclin dependent kinase (CDK), some pro-apoptotic and anti-apoptotic proteins, and P53 have been shown to be regulated by metabolic crosstalk. Dysregulation of this cross-talk between metabolism and cell cycle leads to degenerative disorder(s) and cancer. It is not fully understood the actual reason of aberration between metabolism and cell cycle, but it is a hallmark of cancer research. Herein, we discussed the role of some regulatory molecules relative of cell cycle and metabolism and highlight how they control the function of each other. We also pointed out, current therapeutic opportunities and some additional crucial therapeutic targets on these fields that could be a breakthrough in cancer research. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Effect of KOH concentration on LEO cycle life of IPV nickel-hydrogen flight cells. An update

NASA Technical Reports Server (NTRS)

Smithrick, John J.; Hall, Stephen W.

1991-01-01

An update of validation test results confirming the breakthrough in LEO cycle life of nickel-hydrogen cells containing 26 percent potassium hydroxide (KOH) electrolyte is presented. A breakthrough in the LEO cycle life of individual pressure vessel nickel-hydrogen cells is reported. The cycle life of boiler plate cells containing 26 percent KOH electrolyte was about 40,000 LEO cycles compared to 3500 cycles for cells containing 31 percent KOH.

Effect of KOH concentration on LEO cycle life of IPV nickel-hydrogen flight cells - An update

NASA Technical Reports Server (NTRS)

Smithrick, John J.; Hall, Stephen W.

1991-01-01

An update of validation test results confirming the breakthrough in LEO cycle life of nickel-hydrogen cells containing 26 percent potassium hydroxide (KOH) electrolyte is presented. A breakthrough in the LEO cycle life of individual pressure vessel nickel-hydrogen cells is reported. The cycle life of boiler plate cells containing 26 percent KOH electrolyte was about 40,000 LEO cycles compared to 3500 cycles for cells containing 31 percent KOH.

Effect of LEO cycling on 125 Ah advanced design IPV nickel-hydrogen flight cells - An update

NASA Technical Reports Server (NTRS)

Smithrick, John J.; Hall, Stephen W.

1991-01-01

An update of validation test results confirming the breakthrough in LEO cycle life of nickel-hydrogen cells containing 26 percent potassium hydroxide (KOH) electrolyte is presented. A breakthrough in the LEO cycle life of individual pressure vessel nickel-hydrogen cells is reported. The cycle life of boiler plate cells containing 26 percent KOH electrolyte was about 40,000 LEO cycles compared to 3500 cycles for cells containing 31 percent KOH.

Exploring the Underlying Mechanisms of the Xenopus laevis Embryonic Cell Cycle.

PubMed

Zhang, Kun; Wang, Jin

2018-05-31

The cell cycle is an indispensable process in proliferation and development. Despite significant efforts, global quantification and physical understanding are still challenging. In this study, we explored the mechanisms of the Xenopus laevis embryonic cell cycle by quantifying the underlying landscape and flux. We uncovered the Mexican hat landscape of the Xenopus laevis embryonic cell cycle with several local basins and barriers on the oscillation path. The local basins characterize the different phases of the Xenopus laevis embryonic cell cycle, and the local barriers represent the checkpoints. The checkpoint mechanism of the cell cycle is revealed by the landscape basins and barriers. While landscape shape determines the stabilities of the states on the oscillation path, the curl flux force determines the stability of the cell cycle flow. Replication is fundamental for biology of living cells. We quantify the input energy (through the entropy production) as the thermodynamic requirement for initiation and sustainability of single cell life (cell cycle). Furthermore, we also quantify curl flux originated from the input energy as the dynamical requirement for the emergence of a new stable phase (cell cycle). This can provide a new quantitative insight for the origin of single cell life. In fact, the curl flux originated from the energy input or nutrition supply determines the speed and guarantees the progression of the cell cycle. The speed of the cell cycle is a hallmark of cancer. We characterized the quality of the cell cycle by the coherence time and found it is supported by the flux and energy cost. We are also able to quantify the degree of time irreversibility by the cross correlation function forward and backward in time from the stochastic traces in the simulation or experiments, providing a way for the quantification of the time irreversibility and the flux. Through global sensitivity analysis upon landscape and flux, we can identify the key elements for controlling the cell cycle speed. This can help to design an effective strategy for drug discovery against cancer.

Some Oobservations of the Role of Component Size in Solder Joint Degradation under Thermal Cycling Environments

NASA Technical Reports Server (NTRS)

Winslow, J.; Wen, L-C.

1995-01-01

Experimental results will be presented from a continuing investigation into the influence of component size and configuration of thermal cycling lifetimes, observed in a set of quadpak electronic component packages.

Effect of KOH concentration on LEO cycle life of IPV nickel-hydrogen flight cells-update 2

NASA Technical Reports Server (NTRS)

Smithrick, John J.; Hall, Stephen W.

1991-01-01

An update of validation test results confirming the breakthrough in low earth orbit (LEO) cycle life of nickel-hydrogen cells containing 26 percent KOH electrolyte is presented. A breakthrough in the LEO cycle life of individual pressure vessel (IPV nickel-hydrogen cells has been previously reported. The cycle life of boiler plate cells containing 26 percent potassium hydroxide (KOH) electrolyte was about 40 000 LEO cycles compared to 3500 cycles for cells containing 31 percent KOH. This test was conducted at Hughes Aircraft Company under a NASA Lewis contract. The purpose was to investigate the effect of KOH concentration on cycle life. The cycle regime was a stressful accelerated LEO, which consisted of a 27.5 min charge followed by a 17.5 min discharge (2x normal rate). The depth of discharge (DOD) was 80 percent. The cell temperature was maintained at 23 C. The boiler plate test results are in the process of being validated using flight hardware and real time LEO test at the Naval Weapons Support Center (NWSC), Crane, Indiana under a NASA Lewis Contract. Six 48 Ah Hughes recirculation design IPV nickel-hydrogen flight battery cells are being evaluated. Three of the cells contain 26 percent KOH (test cells), and three contain 31 percent KOH (control cells). They are undergoing real time LEO cycle life testing. The cycle regime is a 90-min LEO orbit consisting of a 54-min charge followed by a 36-min discharge. The depth-of-discharge is 80 percent. The cell temperature is maintained at 10 C. The three 31 percent KOH cells failed (cycles 3729, 4165, and 11355). One of the 26 percent KOH cells failed at cycle 15314. The other two 26 percent KOH cells were cycled for over 16600 cycles during the continuing test.

Recyclable organic solar cells on cellulose nanocrystal substrates

PubMed Central

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

Overcharge tolerant high-temperature cells and batteries

DOEpatents

Redey, Laszlo; Nelson, Paul A.

1989-01-01

In a lithium-alloy/metal sulfide high temperature electrochemical cell, cell damage caused by overcharging is avoided by providing excess lithium in a high-lithium solubility phase alloy in the negative electrode and a specified ratio maximum of the capacity of a matrix metal of the negative electrode in the working phase to the capacity of a transition metal of the positive electrode. In charging the cell, or a plurality of such cells in series and/or parallel, chemical transfer of elemental lithium from the negative electrode through the electrolyte to the positive electrode provides sufficient lithium to support an increased self-charge current to avoid anodic dissolution of the positive electrode components above a critical potential. The lithium is subsequently electrochemically transferred back to the negative electrode in an electrochemical/chemical cycle which maintains high self-discharge currents on the order of 3-15 mA/cm.sup.2 in the cell to prevent overcharging.

Recyclable organic solar cells on cellulose nanocrystal substrates.

PubMed

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.

Origins of correlated spiking in the mammalian olfactory bulb

PubMed Central

Gerkin, Richard C.; Tripathy, Shreejoy J.; Urban, Nathaniel N.

2013-01-01

Mitral/tufted (M/T) cells of the main olfactory bulb transmit odorant information to higher brain structures. The relative timing of action potentials across M/T cells has been proposed to encode this information and to be critical for the activation of downstream neurons. Using ensemble recordings from the mouse olfactory bulb in vivo, we measured how correlations between cells are shaped by stimulus (odor) identity, common respiratory drive, and other cells’ activity. The shared respiration cycle is the largest source of correlated firing, but even after accounting for all observable factors a residual positive noise correlation was observed. Noise correlation was maximal on a ∼100-ms timescale and was seen only in cells separated by <200 µm. This correlation is explained primarily by common activity in groups of nearby cells. Thus, M/T-cell correlation principally reflects respiratory modulation and sparse, local network connectivity, with odor identity accounting for a minor component. PMID:24082089

Screening of Small Molecule Interactor Library by Using In-Cell NMR Spectroscopy (SMILI-NMR)

PubMed Central

Xie, Jingjing; Thapa, Rajiv; Reverdatto, Sergey; Burz, David S.; Shekhtman, Alexander

2011-01-01

We developed an in-cell NMR assay for screening small molecule interactor libraries (SMILI-NMR) for compounds capable of disrupting or enhancing specific interactions between two or more components of a biomolecular complex. The method relies on the formation of a well-defined biocomplex and utilizes in-cell NMR spectroscopy to identify the molecular surfaces involved in the interaction at atomic scale resolution. Changes in the interaction surface caused by a small molecule interfering with complex formation are used as a read-out of the assay. The in-cell nature of the experimental protocol insures that the small molecule is capable of penetrating the cell membrane and specifically engaging the target molecule(s). Utility of the method was demonstrated by screening a small dipeptide library against the FKBP–FRB protein complex involved in cell cycle arrest. The dipeptide identified by SMILI-NMR showed biological activity in a functional assay in yeast. PMID:19422228