Search Results
Results 351 - 400 of 2140
< 3 4 5 6 7 8 9 10 11 12 13 >
Mukherjee Chandrama - - 2009
Accumulation of multiple copies of the genome in a single nucleus and several nuclei in a single cell has previously been noted in Entamoeba histolytica, contributing to the genetic heterogeneity of this unicellular eukaryote. In this study, we demonstrate that this genetic heterogeneity is an inherent feature of the cell ...
Lan Ganhui - - 2009
Forces are important in biological systems for accomplishing key cell functions, such as motility, organelle transport, and cell division. Currently, known force generation mechanisms typically involve motor proteins. In bacterial cells, no known motor proteins are involved in cell division. Instead, a division ring (Z-ring) consists of mostly FtsZ, FtsA, ...
Allard Jun F - - 2009
FtsZ, a bacterial homologue of tubulin, plays a central role in bacterial cell division. It is the first of many proteins recruited to the division site to form the Z-ring, a dynamic structure that recycles on the time scale of seconds and is required for division to proceed. FtsZ has ...
Slayden Richard A - - 2009
OBJECTIVES: Universally conserved events in cell division provide the opportunity for the development of novel chemotherapeutics against Mycobacterium tuberculosis. The aim of this study was to use the beta-lactam antimicrobials cefalexin and piperacillin to inhibit FtsI and characterize the morphological changes and global transcriptional activities of genes to identify a ...
Gregory James A JA Division of Biological Sciences, University of California at San Diego, La Jolla, California 92093, - - 2008
Division site selection in rod-shaped bacteria depends on nucleoid occlusion, which prevents division over the chromosome and MinCD, which prevent division at the poles. MinD is thought to localize MinC to the cell poles where it prevents FtsZ assembly. Time-lapse microscopy demonstrates that in Bacillus subtilis transient polar FtsZ rings ...
Larson-Rabin Zachary - - 2009
Endoreduplication, a modified cell cycle that allows cells to increase ploidy without subsequent cell division, is a key component of plant growth and development. In this work, we show that some, but not all, of the endoreduplication of Arabidopsis (Arabidopsis thaliana) is mediated by the expression of a WD40 gene, ...
Li, Shenghua
<i>Caulobacter crescentus</i> is an important model organism for studying regulation of cell growth, division and differentiation in prokaryotes. <i>C. crescentus</i> undergoes asymmetric division producing two progeny cells with identical genome but different developmental programs: the "swarmer" cell is flagellated and motile, and the "stalked" cell is sessile (attached to a ...
Willemsen Viola - - 2008
Because plant cells do not migrate, cell division planes are crucial determinants of plant cellular architecture. In Arabidopsis roots, stringent control of cell divisions leads to a virtually invariant division pattern, including those that create new tissue layers. However, the mechanisms that control oriented cell divisions are hitherto poorly understood. ...
Lesterlin Christian - - 2008
Bacterial chromosomes are organised as two replichores of opposite polarity that coincide with the replication arms from the ori to the ter region. Here, we investigated the effects of asymmetry in replichore organisation in Escherichia coli. We show that large chromosome inversions from the terminal junction of the replichores disturb ...
Mileykovskaya Eugenia - - 2009
The pgsA null Escherichia coli strain, UE54, lacks the major anionic phospholipids phosphatidylglycerol and cardiolipin. Despite these alterations the strain exhibits relatively normal cell division. Analysis of the UE54 phospholipids using negativeion electrospray ionization mass spectrometry resulted in identification of a new anionic phospholipid, N-acylphosphatidylethanolamine. Staining with the fluorescent dye ...
Okubo-Kurihara Emiko - - 2009
Aquaporin is a water channel that increases water permeability through membranous structures. In plants, vacuoles are essential organelles that undergo dynamic volume changes during cell growth. To understand the contribution of aquaporins to plant cell growth, we developed a transgenic tobacco BY-2 cell line overexpressing the tonoplast intrinsic protein (TIP), ...
Takaki Tohru - - 2008
Polo-like kinase 1 (Plk1) is a key regulator of cell division in eukaryotic cells. In this review we focus on recent leaps in our understanding of how Plk1 controls cytokinesis, the final stage of cell division. Furthermore, we will go beyond mitosis to highlight unexpected roles of Plk1 during interphase ...
Kelley M J - - 2009
Primary open-angle glaucoma is recognized as a disease of aging, and studies show a relationship between aging and trabecular meshwork (TM) cell density. Human TM cell division occurs primarily in the anterior, non-filtering region. A commonly used glaucoma treatment, laser trabeculoplasty (LTP), triggers and increases cell division, as well as ...
Xu Xianfeng Morgan - - 2008
In higher plants, the plane of cell division is faithfully predicted by the preprophase band (PPB). The PPB, a cortical ring of microtubules and F-actin, disassembles upon nuclear-envelope breakdown. During cytokinesis, the expanding cell plate fuses with the plasma membrane at the cortical division site, the site of the former ...
Samson Rachel Y RY Medical Research Council (MRC) Cancer Cell Unit, Hills Road, Cambridge CB2 0XZ, - - 2008
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 ...
Wang Shufang - - 2009
Mouse oocytes undergo two successive meiotic divisions to generate one large egg with two small polar bodies. The divisions are essential for preserving the maternal resources to support embryonic development. Although previous studies have shown that some small guanosine triphosphatases, such as RAC, RAN, and CDC42, play important roles in ...
Jaffe Aron B - - 2008
The establishment of apical-basal polarity within a single cell and throughout a growing tissue is a key feature of epithelial morphogenesis. To examine the underlying mechanisms, the human intestinal epithelial cell line Caco-2 was grown in a three-dimensional matrix to generate a cystlike structure, where the apical surface of each ...
Zadrag-Tecza Renata - - 2009
The number of cell divisions of the yeast Saccharomyces cerevisiae is limited, referred to as "replicative lifespan" of this organism and believed to be due to aging mechanisms similar to those of mammalian cells. We demonstrate, using three pairs of isogenic yeast strains (standard and a mutant deficient in an ...
Lindås Ann-Christin - - 2008
In contrast to the cell division machineries of bacteria, euryarchaea, and eukaryotes, no division components have been identified in the second main archaeal phylum, Crenarchaeota. Here, we demonstrate that a three-gene operon, cdv, in the crenarchaeon Sulfolobus acidocaldarius, forms part of a unique cell division machinery. The operon is induced ...
Apostolakos Panagiotis - - 2008
In the present study, the involvement of phospholipase C and D (PLC and PLD) pathways in the asymmetric divisions that produce the stomatal complexes of Zea mays was investigated. In particular, the polar organization of microtubules (MTs) and actin filaments (AFs) and the process of asymmetric division were studied in ...
De Smet Ive - - 2008
During the development of multicellular organisms, organogenesis and pattern formation depend on formative divisions to specify and maintain pools of stem cells. In higher plants, these activities are essential to shape the final root architecture because the functioning of root apical meristems and the de novo formation of lateral roots ...
Bramkamp Marc - - 2008
Cell division in bacteria is governed by a complex cytokinetic machinery in which the key player is a tubulin homologue, FtsZ. Most rod-shaped bacteria divide precisely at mid-cell between segregated sister chromosomes. Selection of the correct site for cell division is thought to be determined by two negative regulatory systems: ...
Ghosh Biplab - - 2008
When a bacterium divides, its cell wall at the division site grows radially inward like the shutter of a camera and guillotines the cell into two halves. The wall is pulled upon from inside by a polymeric ring, which itself shrinks in radius. The ring is made of an intracellular ...
Sano Toshio - - 2009
Potassium ions (K+) are required for plant growth and development, including cell division and cell elongation/expansion, which are mediated by the K+ transport system. In this study, we investigated the role of K+ in cell division using tobacco BY-2 protoplast cultures. Gene expression analysis revealed induction of the Shaker-like outward ...
Patrick Joyce E - - 2008
In Bacillus subtilis, FtsZ ring formation and cell division is favoured at the midcell because the inhibitor proteins MinC and MinD are indirectly restricted to the cell poles by the protein DivIVA. Here we identify MinJ, a topological determinant of medial FtsZ positioning that acts as an intermediary between DivIVA ...
Zhong Weimin - - 2008
From invertebrates to mammals, cell-cycle progression during an asymmetric cell division is accompanied by precisely timed redistribution of cell-fate determinants so that they segregate asymmetrically to enable the two daughter cells to choose different fates. Interestingly, studies on how cell fates are specified in such divisions reveal that the same ...
Braun Nils - - 2008
AUXIN BINDING PROTEIN1 (ABP1) has long been characterized as a potentially important mediator of auxin action in plants. Analysis of the functional requirement for ABP1 during development was hampered because of embryo lethality of the null mutant in Arabidopsis thaliana. Here, we used conditional repression of ABP1 to investigate its ...
Jurado Silvia - - 2008
The ubiquitin pathway is emerging as a powerful system that controls the stability of key regulatory proteins. In plants, this pathway plays an important role in controlling several developmental processes, responses to environmental changes and also cell division. Arabidopsis SKP2A is an F-box protein that regulates the stability of the ...
Gillard Jeroen - - 2008
Despite the growing interest in diatom genomics, detailed time series of gene expression in relation to key cellular processes are still lacking. Here, we investigated the relationships between the cell cycle and chloroplast development in the pennate diatom Seminavis robusta. This diatom possesses two chloroplasts with a well-orchestrated developmental cycle, ...
Adl, Sina M.
The ccl mutant is temperature sensitive and arrests the cell cycle at 34.4° C. The transition point for division under restrictive conditions defines the point of commitment to division. We have examined the point of commitment to division in relation to the time course of stomatogenesis and micronuclear mitosis in ...
Tyson John J - - 2008
The coordination of growth, DNA replication and division in proliferating cells can be adequately explained by a 'clock + checkpoint' model. The clock is an underlying cyclical sequence of states; the checkpoints ensure that the cycle proceeds without mistakes. From the molecular complexities of the control system in modern eukaryotes, ...
Qu Liang-Huan - - 2008
In addition to the mechanical forces of the external environment, the individual plant cell is also subject to multiple subtle biophysical forces that arise from neighboring cell growth and division within the tissue. To maintain a normal cell shape and division pattern, the plant cell is proposed to have the ...
Efroni Idan - - 2008
Leaf development has been monitored chiefly by following anatomical markers. Analysis of transcriptome dynamics during leaf maturation revealed multiple expression patterns that rise or fall with age or that display age-specific peaks. These were used to formulate a digital differentiation index (DDI) based on a set of selected markers with ...
Grenga Lucia - - 2008
FtsK is a multifunctional protein involved in both cell division and chromosome segregation. As far as its role in cell division is concerned, FtsK is among the first divisome proteins that localizes at mid-cell, after FtsZ, FtsA and ZipA, and is required for the recruitment of the other divisome components. ...
Kang Yong Won - - 2008
The Arabidopsis bypass1 mutant (bps1) exhibits defective shoot and root growth that is associated with constitutive production of a root-derived carotenoid-related signal (Van Norman et al., Curr Biol 14:1739-1746, 2004). Since the identity of the signal and the function of BPS1 are still unknown, we investigated effects of BPS1 depletion ...
Han Ye - - 2008
Root growth is mainly determined by cell division and subsequent elongation in the root apical area. Components regulating cell division in root meristematic cells are largely unknown. Previous studies have identified rice (Oryza sativa) ROOT ARCHITECTURE ASSOCIATED1 (OsRAA1) as a regulator in root development. Yet, the function of OsRAA1 at ...
Oh Sung-Aeong - - 2008
Asymmetric cell division at pollen mitosis I (PMI) is required to specify the differential fate of the daughter vegetative and generative cells. Cytokinesis at PMI displays specialized features, and it has been suggested that there might be distinct molecular pathways underpinning different modes of cytokinesis in plants. Activation of the ...
Tisné Sébastien - - 2008
Both leaf production and leaf expansion are tightly linked to cell expansion and cell division, but the functional relationships between all these variables are not clearly established. To get insight into these relationships, a quantitative genetic analysis was performed in 118 recombinant inbred lines derived from a cross between the ...
Sado Kamdem S - - 2008
The effect of non-inhibitory concentrations of capric, lauric and alpha-linolenic acids (C10:0, C12:0 and C18:3 respectively) on the division time distribution of single cells of Staphylococcus aureus was evaluated at pH 7 and pH 5. The effect of the initial cell concentration on the lag time of growing cell populations ...
Mahajan Babita - - 2008
Molecules and cellular mechanisms that regulate the process of cell division in malaria parasites remain poorly understood. In this study we isolate and characterize the four Plasmodium falciparum centrins (PfCENs) and, by growth complementation studies, provide evidence for their involvement in cell division. Centrins are cytoskeleton proteins with key roles ...
Jessop Lea - - 2008
Budding yeast lacking the Sgs1 helicase and the Mus81/Mms4 endonuclease are inviable, and indirect studies implicate homologous recombination gone awry as the cause of death. We show that mutants lacking both enzymes have profound defects in meiotic recombination intermediate metabolism and crossover (CO) formation. Recombination intermediates (joint molecules, JMs) accumulate ...
Katsuki Yoko - - 2008
Aneuploidy has been implicated as an important step leading to various neoplasias. Although genetic factors that block aneuploidy have been the subject of intense interest, the impact of pharmacological and environmental substances on the development of aneuploidy has not been studied. Here, we show that caffeine induces aneuploidy through asymmetrical ...
Fujiwara Kitao - - 2008
SiO(2) nano-particles were found to exhibit size-dependent toxicity toward the alga, Chlorella kessleri. Small SiO(2) nano-particles exhibit stronger toxicity: 50% inhibitory concentrations (IC(50)) value for 5 nm = 0.8 +/- 0.6%, 26 nm = 7.1 +/- 2.8%, and 78 nm = 9.1 +/- 4.7%. Enlargement of the cell body was ...
Park Sookhee - - 2008
CDC48/p97 is a conserved homohexameric AAA-ATPase chaperone required for a variety of cellular processes but whose role in the development of a multicellular model system has not been examined. Here, we have used reverse genetics, visualization of a functional Arabidopsis (Arabidopsis thaliana) CDC48 fluorescent fusion protein, and morphological analysis to ...
Rast Madlen I - - 2008
In plant shoot meristems, cells with indeterminate fate are separated from determinate organ founder cells by morphological boundaries. Organ founder cells are selected at sites of auxin accumulation. Auxin is channeled between cells via efflux carrier proteins, but influx carriers are needed to concentrate auxin in the outer meristem layer. ...
Sugimoto Shinya - - 2008
A balance of the intracellular concentrations of molecular chaperones in response to environmental conditions is of considerable importance for cellular homeostasis. Here, the physiological consequences of overexpression of GrpE in wild-type Escherichia coli MC4100 were examined. Overexpression of GrpE resulted in defects in cell division and growth, but overexpression of ...
Turner Marian L - - 2008
Differentiation to Ab secreting and isotype-switched effector cells is tightly linked to cell division and therefore the degree of proliferation strongly influences the nature of the immune response. The maximum number of divisions reached, termed the population division destiny, is stochastically distributed in the population and is an important parameter ...
Dubrovsky Joseph G - - 2008
Plants exhibit an exceptional adaptability to different environmental conditions. To a large extent, this adaptability depends on their ability to initiate and form new organs throughout their entire postembryonic life. Plant shoot and root systems unceasingly branch and form axillary shoots or lateral roots, respectively. The first event in the ...
Hao Nan - - 2008
Cell differentiation requires the ability to detect and respond appropriately to a variety of extracellular signals. Here we investigate a differentiation switch induced by changes in the concentration of a single stimulus. Yeast cells exposed to high doses of mating pheromone undergo cell division arrest. Cells at intermediate doses become ...
Fuad-Hassan Avan - - 2008
The growth and emergence of maize silks has a considerable importance in yield determination under drought conditions. Spatial and temporal patterns of the rates of tissue expansion and of cell division were characterized in silks of plants subjected to different soil water potentials. In all cases, silk development consisted of ...
< 3 4 5 6 7 8 9 10 11 12 13 >