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Results 351 - 400 of 2155
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Barhoover Melissa A - - 2010
The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor with constitutive activities and those induced by xenobiotic ligands, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). One unexplained cellular role for the AHR is its ability to promote cell cycle progression in the absence of exogenous ligands, whereas treatment with exogenous ligands induces ...
Reddy Akhilesh B - - 2010
Circadian rhythms permeate mammalian biology. They are manifested in the temporal organisation of behavioural, physiological, cellular and neuronal processes. Whereas it has been shown recently that these approximately 24-hour cycles are intrinsic to the cell and persist in vitro, internal synchrony in mammals is largely governed by the hypothalamic suprachiasmatic ...
Martin Sophie G - - 2009
How do cells sense their own size and shape? And how does this information regulate progression of the cell cycle? Our group, in parallel to that of Paul Nurse, have recently demonstrated that fission yeast cells use a novel geometry-sensing mechanism to couple cell length perception with entry into mitosis. ...
van Duursen Majorie B M - - 2010
Cytochrome P450c17 (CYP17) has been linked to various hormone-related diseases, including breast cancer, thus being a potential target for cancer chemoprevention. We studied the naturally occurring phytochemical enterolactone (ENL) and 13 VIOXX-related lactone derivatives (CRI-1 to CRI-13) for their effects on CYP17 activity and expression and on cell cycle status ...
Ka┼║mierczak Andrzej - - 2010
Analyses of DNA content using fluorescence microcytophotometry showed that development of Anemia phyllitidis gametophytes coincided with endoreduplication process. The level of this process shown by the number of endopolyploid cells studied at the I-V arbitrarily established cellular gametophyte stages, was 3%, while at the VI-VII and VII* (male stages) were ...
Angelastro Peter S - - 2010
The phosphorylated form of the response regulator CtrA represses DNA replication initiation and regulates the transcription of about 100 cell cycle-regulated genes in Caulobacter crescentus. CtrA activity fluctuates during the cell cycle, and its periodicity is a key element of the engine that drives cell cycle progression. The histidine kinase ...
Daigle Derek - - 2010
A fundamental problem in studying the latent-to-lytic switch of Epstein-Barr virus (EBV) and the viral lytic cycle itself is the lack of a culture system fully permissive to lytic cycle induction. Strategies to target EBV-positive tumors by inducing the viral lytic cycle with chemical agents are hindered by inefficient responses ...
Lin Wei - - 2009
MSP58, a 58-kD nuclear microspherule protein, is an evolutionarily conserved nuclear protein implicated in the regulation of gene transcription as well as in malignant transformation. An analysis of mRNA expression by real-time PCR revealed that MSP58 was significantly up-regulated in 29% of high-grade glioblastoma tissues as well as in four ...
Liu Da-Zhi - - 2009
Ahead of Print article withdrawn by publisher. Classically, the cell cycle is regarded as the central process leading to cellular proliferation. However, increasing evidence has substantiated the concept that cell cycle re-entry by neurons leads to post-mitotic death. A neuron that re-enters the cell cycle can neither advance to a ...
Dissmeyer Nico - - 2009
Entry into mitosis is universally controlled by cyclin-dependent kinases (CDKs). A key regulatory event in metazoans and fission yeast is CDK activation by the removal of inhibitory phosphate groups in the ATP binding pocket catalyzed by Cdc25 phosphatases. In contrast with other multicellular organisms, we show here that in the ...
Mat?a Isabel - - 2010
Seeds of Arabidopsis thaliana were sent to space and germinated in orbit. Seedlings grew for 4d and were then fixed in-flight with paraformaldehyde. The experiment was replicated on the ground in a Random Positioning Machine, an effective simulator of microgravity. In addition, samples from a different space experiment, processed in ...
Adams Tom - - 2010
A population of peripheral retinal pigment epithelium (RPE) cells in mature pigmented rats are retained in the cell cycle and divide, as determined by Ki67 and BrdU labeling. Their cell cycle rate is approximately 5 days. Ten times as many Ki67 positive cells are found in albinos compared with pigmented ...
Wang Peng P Departments of Pathology and Pharmacology, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania, - - 2009
microRNAs (miRNA) are small noncoding RNAs that participate in diverse biological processes by suppressing target gene expression. Altered expression of miR-21 has been reported in cancer. To gain insights into its potential role in tumorigenesis, we generated miR-21 knockout colon cancer cells through gene targeting. Unbiased microarray analysis combined with ...
Wäsch R R Department of Hematology and Oncology, University Medical Center, Freiburg, Germany. - - 2010
Deregulation of the G1/G0 phase of the cell cycle can lead to cancer. During G1, most cells commit alternatively to DNA replication and division, or to cell-cycle exit and differentiation. The anaphase-promoting complex or cyclosome (APC/C) activated by Cdh1 coordinately eliminates positive cell-cycle regulators as well as inhibitors of differentiation, ...
Pomerening Joseph R JR Department of Biology, Interdisciplinary Program in Biochemistry, Indiana University, 212 S. Hawthorne Drive Simon Hall Room 043F, Bloomington, IN 47405-7003, United States. - - 2009
A positive-feedback loop is a simple motif that is ubiquitous to the modules and networks that comprise cellular signaling systems. Signaling behaviors that are synonymous with positive feedback include amplification and rapid switching, maintenance, and the coherence of outputs. Recent advances have been made towards understanding how positive-feedback loops function, ...
Wang Jue D JD Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA. - - 2009
Adaptation to fluctuations in nutrient availability is a fact of life for single-celled organisms in the 'wild'. A decade ago our understanding of how bacteria adjust cell cycle parameters to accommodate changes in nutrient availability stemmed almost entirely from elegant physiological studies completed in the 1960s. In this Opinion article ...
Li Wan-Feng - - 2009
Climate change such as changing temperature and increasing concentrations of atmospheric CO(2), are likely to drive significant modifications in forests. While many studies have demonstrated the responses and adoptions of tree to fluctuations in climatic and environmental conditions, the impact of environmental signals on trees is complex and poorly understood ...
Ninov Nikolay - - 2009
Although the molecular elements controlling cell cycle progression are well established, the mechanisms regulating how cell proliferation is triggered in response to extrinsic stimuli and how cell divisions change speed, particularly in stem or tumor cells or regenerative tissues, are poorly understood. One exceptional model system in which these events ...
Boheler Kenneth R - - 2009
Embryonic stem (ES) and induced pluripotent stem (iPS) cells self-renew and are pluripotent. Differentiation of these cells can yield over 200 somatic cell types, making pluripotent cells an obvious source for regenerative medicine. Before the potential of these cells can be maximally harnessed for clinical applications, it will be necessary ...
Zhou Jue-Yu - - 2009
Cell cycle progression is regulated by both transcriptional and post-transcriptional mechanisms. MicroRNAs (miRNAs) emerge as a new class of small non-coding RNA regulators of cell cycle as recent evidence suggests. It is hypothesized that expression of specific miRNAs oscillates orderly along with cell cycle progression. However, the oscillated expression patterns ...
Jenal Urs - - 2009
Caulobacter crescentus cell cycle progression is implemented by oscillating global transcriptional regulators that establish temporal and spatial control of modular genetic subsystems during the cell cycle. The hierarchy of this regulatory circuit is established through a combination of gene expression control and regulated proteolysis. Recent results highlight the importance of ...
Lal Ashish A Immune Disease Institute, Children's Hospital Boston, Department of Pediatrics, Harvard Medical School, MA 02115, USA. - - 2009
miR-24, upregulated during terminal differentiation of multiple lineages, inhibits cell-cycle progression. Antagonizing miR-24 restores postmitotic cell proliferation and enhances fibroblast proliferation, whereas overexpressing miR-24 increases the G1 compartment. The 248 mRNAs downregulated upon miR-24 overexpression are highly enriched for DNA repair and cell-cycle regulatory genes that form a direct interaction ...
Taylor James A - - 2009
Periodic activation and deactivation of the essential transcriptional regulator CtrA is necessary to drive cell cycle progression in Caulobacter crescentus. At the onset of DNA replication (the G1-S cell cycle transition), CtrA and the AAA+ protease ClpXP colocalize at one cell pole along with three accessory proteins, RcdA, CpdR, and ...
Kabani Sarah - - 2010
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 ...
Hoffman-Sommer Marta - - 2009
The proteins Ccz1 and Mon1 are known to function together with the Rab-GTPase Ypt7 in membrane fusion reactions at the yeast vacuole. In a genome-wide analysis they have also been found to interact genetically with the nuclear-migration protein Num1. In this study we analyze these synthetic effects and we show ...
Fagarasanu Andrei A Department of Cell Biology and 2 Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G2H7, - - 2009
In Saccharomyces cerevisiae, the class V myosin motor Myo2p propels the movement of most organelles. We recently identified Inp2p as the peroxisome-specific receptor for Myo2p. In this study, we delineate the region of Myo2p devoted to binding peroxisomes. Using mutants of Myo2p specifically impaired in peroxisome binding, we dissect cell ...
Friedman Avner - - 2010
Cell cycle is controlled at two restriction points, R (1) and R (2). At both points the cell will commit apoptosis if it detects irreparable damage. But at R (1) an undamaged cell also decides whether to proceed to the S phase or go into a quiescent mode, depending on ...
Buck Sarah H SH Department of Genetics, Dartmouth Medical School, Hanover, NH 03755, - - 2009
Cyclin-dependent kinase inhibitors (CKIs) are major contributors to the decision to enter or exit the cell cycle. The Caenorhabditis elegans genome encodes two CKIs belonging to the Cip/Kip family, cki-1 and cki-2. cki-1 has been shown to act as a canonical negative regulator of cell cycle entry, while the role ...
Varodayan Florence P FP Division of Neurology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, - - 2009
A prolonged seizure, status epileptics (SE), is a potent stimulus for increased neurogenesis in the dentate gyrus of the hippocampus. Molecular mechanisms that regulate normal and pathologic cell birth in the dentate gyrus are poorly understood. Lithium-pilocarpine was used to induce SE in immature postnatal day 20 rats. Newborn cells ...
Singh Amar M AM Department of Biochemistry and Molecular Biology, Paul D. Coverdell Center for Biomedical and Health Sciences, The University of Georgia, Athens, GA 30602, - - 2009
Pluripotent stem cells have long-term proliferative capacity and an unusual mode of cell-cycle regulation and can divide independently of extrinsic mitogenic signals. The last few years has seen evidence emerge that links cell-cycle regulation to the maintenance and establishment of pluripotency. Myc transcription factors appear to be central to this ...
Countryman Jill - - 2009
Epstein-Barr virus (EBV) can be reactivated from latency into the lytic cycle by many stimuli believed to operate by different mechanisms. Cell lines containing EBV differ in their responses to inducing stimuli, yet all stimuli require de novo protein synthesis (44). A crucial step preliminary to identifying these proteins and ...
Lei Hong - - 2009
The PI3K/AKT signaling pathway contributes to cell cycle progression of cytokine-dependent hematopoietic cells under normal conditions, and it is absolutely required to override DNA damage-induced cell cycle arrest checkpoints in these cells. Phosphatidylinositol-3-kinase (PI3K)/AKT activity also correlates with Cdk2 activity in hematopoietic cells, suggesting that Cdk2 activation may be a ...
Li Shenghua - - 2009
The asymmetric cell division cycle of Caulobacter crescentus is orchestrated by an elaborate gene-protein regulatory network, centered on three major control proteins, DnaA, GcrA and CtrA. The regulatory network is cast into a quantitative computational model to investigate in a systematic fashion how these three proteins control the relevant genetic, ...
Siegal-Gaskins Dan - - 2009
In both prokaryotic and eukaryotic cells, gene expression is regulated across the cell cycle to ensure "just-in-time" assembly of select cellular structures and molecular machines. However, present in all time-series gene expression measurements is variability that arises from both systematic error in the cell synchrony process and variance in the ...
Ishida Takashi - - 2009
Endoreduplication involves a doubling of chromosomal DNA without corresponding cell division. In plants, many cell types transit from the mitotic cycle to the endoreduplication cycle or endocycle, and this transition is often coupled with the initiation of cell expansion and differentiation. Although a number of cell cycle regulators implicated in ...
Schroering Allen G - - 2009
Alkylation chemotherapy has been a long-standing treatment protocol for human neoplasia. N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) is a direct-acting monofunctional alkylator. Temozolomide is a clinical chemotherapeutic equivalent requiring metabolic breakdown to the alkylating agent. Both chemicals have similar mechanistic efficacy against DNA mismatch repair-proficient tumor cells that lack expression of methylguanine methyltransferase. Clinically ...
Li Fuhai F Department of Information Science, School of Mathematical Sciences, and LMAM, Peking University, Beijing 100871, China. - - 2010
Automated cell segmentation and tracking are critical for quantitative analysis of cell cycle behavior using time-lapse fluorescence microscopy. However, the complex, dynamic cell cycle behavior poses new challenges to the existing image segmentation and tracking methods. This paper presents a fully automated tracking method for quantitative cell cycle analysis. In ...
Sabelli Paolo A - - 2009
Development of the seed endosperm involves several different types of coordinated cell cycle programs: acytokinetic mitosis, which produces a syncytium soon after fertilization; cellularization through the formation of modified phragmoplasts; cell proliferation, in which mitosis is coupled to cell division; and, in certain species like cereal crops, endoreduplication. Understanding the ...
Zhang Nianxiang - - 2009
Cell division cycle 5-like protein (Cdc5L) is a core component of the putative E3 ubiquitin ligase complex containing Prp19/Pso4, Plrg1 and Spf27. This complex has been shown to have a role in pre-messenger RNA splicing from yeast to humans; however, more recent studies have described a function for this complex ...
Trageser Daniel D Leukemia and Lymphoma Program, Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA 90027, - - 2009
B cell lineage acute lymphoblastic leukemia (ALL) arises in virtually all cases from B cell precursors that are arrested at pre-B cell receptor-dependent stages. The Philadelphia chromosome-positive (Ph(+)) subtype of ALL accounts for 25-30% of cases of adult ALL, has the most unfavorable clinical outcome among all ALL subtypes and ...
Pan Kally Z KZ Microbiology Department, Columbia University College of Physicians and Surgeons, New York, NY 10032, - - 2009
Cells often grow to a certain cell size before entering mitosis and dividing. Two recent articles suggest that fission yeast cells sense their own size through the action of an intracellular gradient emanating from cell tips and a sensor at the cell middle.
Tzur Amit A Department of Systems Biology, Harvard Medical School, Boston, MA 02115, - - 2009
A long-standing question in biology is whether there is an intrinsic mechanism for coordinating growth and the cell cycle in metazoan cells. We examined cell size distributions in populations of lymphoblasts and applied a mathematical analysis to calculate how growth rates vary with both cell size and the cell cycle. ...
Zhao Junpeng - - 2009
It has been demonstrated that during neurogenesis in the mammalian brain, cell-cycle lengthening in neuronal progenitors may cause them to switch from proliferation to neuron-generating division. However, little is known about the cellular mechanisms involved in lengthening of the cell cycle. Growth-associated protein-43 (GAP-43) is a nervous system-specific protein whose ...
Kobayashi Hajime H Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, - - 2009
ATP-driven proteolysis plays a major role in regulating the bacterial cell cycle, development and stress responses. In the nitro -fixing symbiosis with host plants, Sinorhizobium meliloti undergoes a profound cellular differentiation, including endoreduplication of the ome. The regulatory mechanisms governing the alterations of the S. meliloti cell cycle in planta ...
Lavi Orit - - 2009
The cell cycle is one of the best studied cellular mechanisms at the experimental and theoretical levels. Although most of the important biochemical components and reactions of the cell cycle are probably known, the precise way the cell cycle dynamics are driven is still under debate. This phenomenon is not ...
Pizay Marie-Dominique - - 2009
We describe remarkable diurnal changes in the morphology of the planktonic dinoflagellate Ceratium ranipes. The species is distinguished by the unusual appendages, known as toes or fingers, protruding from its horns. Varieties have been described based on the characteristics of the fingers. We discovered that cultures, maintained on a 12:12 ...
Achard Patrick - - 2009
Plant growth involves the integration of many environmental and endogenous signals that together with the intrinsic genetic program determine plant size. At the cellular level, growth rate is regulated by the combined activity of two processes: cell proliferation and expansion. Gibberellins (GA) are plant-specific hormones that play a central role ...
Barry Evan R - - 2009
Mouse embryonic stem cells (ESCs) proliferate with rapid cell cycle kinetics but without loss of pluripotency. The histone methyltransferase Dot1L is responsible for methylation of histone H3 at lysine 79 (H3K79me). We investigated whether ESCs require Dot1L for proper stem cell behavior. ESCs deficient in Dot1L tolerate a nearly complete ...
Fu Da - - 2009
Phosphatidylcholine-specific phospholipase C (PC-PLC) is involved in the cell signal transduction, cell proliferation, and apoptosis. The mechanism of its action, however, has not been fully understood, particularly, the role of PC-PLC in the cell cycle. In the present study, we found that cell division cycle 20 homolog (Cdc20) and PC-PLC ...
Vanstraelen Marleen - - 2009
Plant organs originate from meristems where stem cells are maintained to produce continuously daughter cells that are the source of different cell types. The cell cycle switch gene CCS52A, a substrate specific activator of the anaphase promoting complex/cyclosome (APC/C), controls the mitotic arrest and the transition of mitotic cycles to ...
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