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991.
Sophie Herszterg Andrea Leibfried Floris Bosveld Charlotte Martin Yohanns Bellaiche 《Developmental cell》2013,24(3):256-270
Highlights? During cytokinesis, neighboring cells accumulate MyoII at the edges of the furrow ? MyoII nonautonomously sets the initial geometry of the daughter cell interface ? Neighboring membranes impede adherens junction (AJ) formation until a midbody forms ? Arp2/3-dependent actin accumulation in the dividing cell maintains AJ geometry 相似文献
992.
Biodiversity of ecological communities has been examined widely. However, comparisons of observed species richness are limited because they fail to reveal what part of the differences are caused by natural variation in species pool size and what part is due to dark diversity – the absence of suitable species from a species pool. In other words, conventional biodiversity inventories do not convey information about how complete local plant communities are. We therefore propose the community completeness concept – a new perspective on the species pool framework. In order to ascertain community completeness, we need to estimate the extent of dark diversity, for which several methods are under development. We recommend the Community Completeness Index based on a log-ratio (or logistic) expression: ln(observed richness/dark diversity). This metric offers statistical advantages over other methods (e.g. the proportion of observed richness from the species pool). We discuss how community completeness can be related to long-term and successional community stability, landscape properties and disturbance patterns as well as to a variety of biotic interactions within and among trophic levels. The community completeness concept is related to but distinctive from the alpha-beta-gamma diversity approach and the community saturation phenomenon. The Community Completeness Index is a valuable metric for comparing biodiversity of different ecosystems for nature conservation. It can be used to measure the success of ecological restoration and vulnerability to invasion by alien species. In summary, community completeness is an interface between observed local observed species richness and dark diversity, which can be useful both in theoretical and applied biodiversity research. 相似文献
993.
Simone Kreutmayer Adam Csordas Jan Kern Viola Maass Giovanni Almanzar Martin Offterdinger Robert Öllinger Matthias Maass Georg Wick 《Cell stress & chaperones》2013,18(3):259-268
We identified increased expression and redistribution of the intracellular protein 60-kDa human heat shock protein (hHSP60) (HSPD1) to the cell surface in human endothelial cells subjected to classical atherosclerosis risk factors and subsequent immunologic cross-reactivity against this highly conserved molecule, as key events occurring early in the process of atherosclerosis. The present study aimed at investigating the role of infectious pathogens as stress factors for vascular endothelial cells and, as such, contributors to early atherosclerotic lesion formation. Using primary donor-matched arterial and venous human endothelial cells, we show that infection with Chlamydia pneumoniae leads to marked upregulation and surface expression of hHSP60 and adhesion molecules. Moreover, we provide evidence for an increased susceptibility of arterial endothelial cells for redistribution of hHSP60 to the cellular membrane in response to C. pneumoniae infection as compared to autologous venous endothelial cells. We also show that oxidative stress has a central role to play in endothelial cell activation in response to chlamydial infection. These data provide evidence for a role of C. pneumoniae as a potent primary endothelial stressor for arterial endothelial cells leading to enrichment of hHSP60 on the cellular membrane and, as such, a potential initiator of atherosclerosis. 相似文献
994.
995.
Irena Axmanová Milan Chytrý Jiří Danihelka Pavel Lustyk Martin Kočí Svatava Kubešová Michal Horsák Mikhail M. Cherosov Paraskovia A. Gogoleva 《Plant Ecology》2013,214(2):207-219
Local species richness–productivity (SR–P) relationship is usually reported as unimodal if long productivity gradients are sampled. However, it tends to be monotonically increasing in low-productive environments due to the decreasing part of the SR–P curve being truncated. Previous work indicated that this can hold true for forest herb layers, because of an upper bound on productivity caused mainly by canopy shading. Here, we ask whether the same pattern exists in a region with an upper bound on productivity caused by a harsh climate. We sampled herbaceous vegetation of boreal forests and grasslands in a low-productive region of central Yakutia (NE Siberia) with dry and winter-cool continental climate. We collected data on species composition, herb-layer productivity (aboveground herbaceous biomass), soil chemistry and light availability. We applied regression models to discriminate between monotonically increasing, decreasing and unimodal responses of herb-layer species richness to measured variables and analysed trends in the species-pool size and beta diversity along the productivity gradient. Our expectation of the monotonically increasing SR–P relationship was confirmed for neither forest herb layers nor grasslands. In the forest herb layers, no relationship was detected. In grasslands, the relationship was unimodal with species richness decline starting at much lower productivity levels than in more productive temperate grasslands. Potential causes for this decline are either limitation of local species richness by the species pool, which contains few species adapted to more productive habitats, or competitive exclusion, which can become an important control of species richness under lower levels of productivity than is the case in temperate grasslands. 相似文献
996.
Lymphatic filariasis is a debilitating disease caused by clade III parasites like Brugia malayi and Wuchereria bancrofti. Current recommended treatment regimen for this disease relies on albendazole, ivermectin and diethylcarbamazine, none of which targets the nicotinic acetylcholine receptors in these parasitic nematodes. Our aim therefore has been to develop adult B. malayi for electrophysiological recordings to aid in characterizing the ion channels in this parasite as anthelmintic target sites. In that regard, we recently demonstrated the amenability of adult B. malayi to patch-clamp recordings and presented results on the single-channel properties of nAChR in this nematode. We have built on this by recording whole-cell nAChR currents from adult B. malayi muscle. Acetylcholine, levamisole, pyrantel, bephenium and tribendimidine activated the receptors on B. malayi muscle, producing robust currents ranging from > 200 pA to ~ 1.5 nA. Levamisole completely inhibited motility of the adult B. malayi within 10 min and after 60 min, motility had recovered back to control values. 相似文献
997.
Yanjiao Zhou Hongyu Gao Kathie A Mihindukulasuriya Patricio S La Rosa Kristine M Wylie Tatiana Vishnivetskaya Mircea Podar Barb Warner Phillip I Tarr David E Nelson J Dennis Fortenberry Martin J Holland Sarah E Burr William D Shannon Erica Sodergren George M Weinstock 《Genome biology》2013,14(1):R1
Background
Characterizing the biogeography of the microbiome of healthy humans is essential for understanding microbial associated diseases. Previous studies mainly focused on a single body habitat from a limited set of subjects. Here, we analyzed one of the largest microbiome datasets to date and generated a biogeographical map that annotates the biodiversity, spatial relationships, and temporal stability of 22 habitats from 279 healthy humans.Results
We identified 929 genera from more than 24 million 16S rRNA gene sequences of 22 habitats, and we provide a baseline of inter-subject variation for healthy adults. The oral habitat has the most stable microbiota with the highest alpha diversity, while the skin and vaginal microbiota are less stable and show lower alpha diversity. The level of biodiversity in one habitat is independent of the biodiversity of other habitats in the same individual. The abundances of a given genus at a body site in which it dominates do not correlate with the abundances at body sites where it is not dominant. Additionally, we observed the human microbiota exhibit both cosmopolitan and endemic features. Finally, comparing datasets of different projects revealed a project-based clustering pattern, emphasizing the significance of standardization of metagenomic studies.Conclusions
The data presented here extend the definition of the human microbiome by providing a more complete and accurate picture of human microbiome biogeography, addressing questions best answered by a large dataset of subjects and body sites that are deeply sampled by sequencing. 相似文献998.
Yaniv Harari Gal-Hagit Romano Lior Ungar Martin Kupiec 《Cell cycle (Georgetown, Tex.)》2013,12(22):3465-3470
Telomeres are nucleoprotein structures that cap the ends of the linear eukaryotic chromosomes, thus protecting their stability and integrity. They play important roles in DNA replication and repair and are central to our understanding of aging and cancer development. In rapidly dividing cells, telomere length is maintained by the activity of telomerase. About 400 TLM (telomere length maintenance) genes have been identified in yeast, as participants of an intricate homeostasis network that keeps telomere length constant. Two papers have recently shown that despite this extremely complex control, telomere length can be manipulated by external stimuli. These results have profound implications for our understanding of cellular homeostatic systems in general and of telomere length maintenance in particular. In addition, they point to the possibility of developing aging and cancer therapies based on telomere length manipulation. 相似文献
999.
Nadine Martin Selina Raguz Gopuraja Dharmalingam Jesús Gil 《Cell cycle (Georgetown, Tex.)》2013,12(14):2194-2199
Cellular senescence is a stable cell cycle arrest that can be induced by stresses such as telomere shortening, oncogene activation or DNA damage. Senescence is a potent anticancer barrier that needs to be circumvented during tumorigenesis. The cell cycle regulator p16INK4a is a key effector upregulated during senescence. Polycomb repressive complexes (PRCs) play a crucial role in silencing the INK4/ARF locus, which encodes for p16INK4a, but the mechanisms by which PRCs are recruited to this locus as well as to other targets remain poorly understood. Recently we discovered the ability of the homeobox proteins HLX1 (H2.0-like homeobox 1) and HOXA9 (Homeobox A9) to bypass senescence. We showed that HLX1 and HOXA9 recruit PRCs to repress INK4a, which constitutes a key mechanism explaining their effects on senescence. Here we provide evidence for the regulation of additional senescence-associated PRC target genes by HLX1 and HOXA9. As both HLX1 and HOXA9 are oncogenes implicated in leukemogenesis, we discuss the implications that the collaboration between Homeobox proteins and PRCs has for senescence and cancer. 相似文献
1000.
Martin Bland 《PloS one》2013,8(10)