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21.
A human natural killer cell subset provides an innate source of IL-22 for mucosal immunity 总被引:2,自引:0,他引:2
Cella M Fuchs A Vermi W Facchetti F Otero K Lennerz JK Doherty JM Mills JC Colonna M 《Nature》2009,457(7230):722-725
Natural killer (NK) cells are classically viewed as lymphocytes that provide innate surveillance against virally infected cells and tumour cells through the release of cytolytic mediators and interferon (IFN)-gamma. In humans, blood CD56(dim) NK cells specialize in the lysis of cell targets. In the lymph nodes, CD56(bright) NK cells secrete IFN-gamma cooperating with dendritic cells and T cells in the generation of adaptive responses. Here we report the characterization of a human NK cell subset located in mucosa-associated lymphoid tissues, such as tonsils and Peyer's patches, which is hard-wired to secrete interleukin (IL)-22, IL-26 and leukaemia inhibitory factor. These NK cells, which we refer to as NK-22 cells, are triggered by acute exposure to IL-23. In vitro, NK-22-secreted cytokines stimulate epithelial cells to secrete IL-10, proliferate and express a variety of mitogenic and anti-apoptotic molecules. NK-22 cells are also found in mouse mucosa-associated lymphoid tissues and appear in the small intestine lamina propria during bacterial infection, suggesting that NK-22 cells provide an innate source of IL-22 that may help constrain inflammation and protect mucosal sites. 相似文献
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V Smetacek C Klaas VH Strass P Assmy M Montresor B Cisewski N Savoye A Webb F d'Ovidio JM Arrieta U Bathmann R Bellerby GM Berg P Croot S Gonzalez J Henjes GJ Herndl LJ Hoffmann H Leach M Losch MM Mills C Neill I Peeken R Röttgers O Sachs E Sauter MM Schmidt J Schwarz A Terbrüggen D Wolf-Gladrow 《Nature》2012,487(7407):313-319
Fertilization of the ocean by adding iron compounds has induced diatom-dominated phytoplankton blooms accompanied by considerable carbon dioxide drawdown in the ocean surface layer. However, because the fate of bloom biomass could not be adequately resolved in these experiments, the timescales of carbon sequestration from the atmosphere are uncertain. Here we report the results of a five-week experiment carried out in the closed core of a vertically coherent, mesoscale eddy of the Antarctic Circumpolar Current, during which we tracked sinking particles from the surface to the deep-sea floor. A large diatom bloom peaked in the fourth week after fertilization. This was followed by mass mortality of several diatom species that formed rapidly sinking, mucilaginous aggregates of entangled cells and chains. Taken together, multiple lines of evidence-although each with important uncertainties-lead us to conclude that at least half the bloom biomass sank far below a depth of 1,000 metres and that a substantial portion is likely to have reached the sea floor. Thus, iron-fertilized diatom blooms may sequester carbon for timescales of centuries in ocean bottom water and for longer in the sediments. 相似文献
24.
Notch-dependent VEGFR3 upregulation allows angiogenesis without VEGF-VEGFR2 signalling 总被引:3,自引:0,他引:3
Benedito R Rocha SF Woeste M Zamykal M Radtke F Casanovas O Duarte A Pytowski B Adams RH 《Nature》2012,484(7392):110-114
Developing tissues and growing tumours produce vascular endothelial growth factors (VEGFs), leading to the activation of the corresponding receptors in endothelial cells. The resultant angiogenic expansion of the local vasculature can promote physiological and pathological growth processes. Previous work has uncovered that the VEGF and Notch pathways are tightly linked. Signalling triggered by VEGF-A (also known as VEGF) has been shown to induce expression of the Notch ligand DLL4 in angiogenic vessels and, most prominently, in the tip of endothelial sprouts. DLL4 activates Notch in adjacent cells, which suppresses the expression of VEGF receptors and thereby restrains endothelial sprouting and proliferation. Here we show, by using inducible loss-of-function genetics in combination with inhibitors in vivo, that DLL4 protein expression in retinal tip cells is only weakly modulated by VEGFR2 signalling. Surprisingly, Notch inhibition also had no significant impact on VEGFR2 expression and induced deregulated endothelial sprouting and proliferation even in the absence of VEGFR2, which is the most important VEGF-A receptor and is considered to be indispensable for these processes. By contrast, VEGFR3, the main receptor for VEGF-C, was strongly modulated by Notch. VEGFR3 kinase-activity inhibitors but not ligand-blocking antibodies suppressed the sprouting of endothelial cells that had low Notch signalling activity. Our results establish that VEGFR2 and VEGFR3 are regulated in a highly differential manner by Notch. We propose that successful anti-angiogenic targeting of these receptors and their ligands will strongly depend on the status of endothelial Notch signalling. 相似文献
25.
Initial sequencing and comparative analysis of the mouse genome 总被引:2,自引:0,他引:2
Mouse Genome Sequencing Consortium Waterston RH Lindblad-Toh K Birney E Rogers J Abril JF Agarwal P Agarwala R Ainscough R Alexandersson M An P Antonarakis SE Attwood J Baertsch R Bailey J Barlow K Beck S Berry E Birren B Bloom T Bork P Botcherby M Bray N Brent MR Brown DG Brown SD Bult C Burton J Butler J Campbell RD Carninci P Cawley S Chiaromonte F Chinwalla AT Church DM Clamp M Clee C Collins FS Cook LL Copley RR Coulson A Couronne O Cuff J Curwen V Cutts T Daly M David R Davies J 《Nature》2002,420(6915):520-562
The sequence of the mouse genome is a key informational tool for understanding the contents of the human genome and a key experimental tool for biomedical research. Here, we report the results of an international collaboration to produce a high-quality draft sequence of the mouse genome. We also present an initial comparative analysis of the mouse and human genomes, describing some of the insights that can be gleaned from the two sequences. We discuss topics including the analysis of the evolutionary forces shaping the size, structure and sequence of the genomes; the conservation of large-scale synteny across most of the genomes; the much lower extent of sequence orthology covering less than half of the genomes; the proportions of the genomes under selection; the number of protein-coding genes; the expansion of gene families related to reproduction and immunity; the evolution of proteins; and the identification of intraspecies polymorphism. 相似文献
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Action de la pepsine sur un flagelle du type «9+1» 总被引:1,自引:0,他引:1
Marina Sileira 《Cellular and molecular life sciences : CMLS》1968,24(12):1243-1245
Summary Enzymatic extraction with pepsin was carried out on ultrathin sections of the 9 + 1 flagella ofDugesia tigrina, using the method ofMonneron andBernhard. The 9 peripheral fibrils and the axial zone of its unique central cylinder become altered within 40 min exposure; following 1 h of incubation these same elements are badly damaged, whereas the cortical sheath and associated radial spokes remain fairly well preserved inside the flagellar membrane. Control sections do not show any sensible alteration. The protein nature of peripheral doublets and axial element of the central cylinder seems therefore indicated; the cortical sheath and the spokes have a very similar, if not identical nature, though their chemical constitution still remains to be investigated. 相似文献
28.
During embryogenesis, cells are spatially patterned as a result of highly coordinated and stereotyped morphogenetic events. In the vertebrate embryo, information on laterality is conveyed to the node, and subsequently to the lateral plate mesoderm, by a complex cascade of epigenetic and genetic events, eventually leading to a left-right asymmetric body plan. At the same time, the paraxial mesoderm is patterned along the anterior-posterior axis in metameric units, or somites, in a bilaterally symmetric fashion. Here we characterize a cascade of laterality information in the zebrafish embryo and show that blocking the early steps of this cascade (before it reaches the lateral plate mesoderm) results in random left-right asymmetric somitogenesis. We also uncover a mechanism mediated by retinoic acid signalling that is crucial in buffering the influence of the flow of laterality information on the left-right progression of somite formation, and thus in ensuring bilaterally symmetric somitogenesis. 相似文献
29.
Rodrigo Rocha Barbosa Marina Vianna Braga Gary James Blomquist Margareth Maria de Carvalho Queiroz 《Journal of Natural History》2017,51(25-26):1491-1498
Cuticular hydrocarbons (CHs) contain complex mixtures of components that cover the surface of all insects to restrict water loss, and in many species function in chemical communication. The complex mixtures have been used as a chemotaxonomic tool since the 1970s. The majority of CH components can be identified by gas chromatography-mass spectrometry (GC-MS), allowing hydrocarbon profiles to be used as chemotaxonomic characters, which can differentiate insect species, including cryptic species. The present study used GC-MS for the identification of CHs of males and females of three species of calliphorids: Cochliomyia macellaria (Fabricius), Hemilucilia segmentaria (Fabricius) and Lucilia cuprina (Wiedmann), A comparison of the chromatographic profiles from the three species allows them to be readily separated. Hydrocarbons identified from the three species contain 23 to 37 carbons and include n-alkanes, methyl-branched alkanes and alkenes. The most abundant compound for both sexes of C. macellaria was n-heptacosane, while for H. segmentaria it was 2-methyltriacontane; for L. cuprina, however, the most abundant compound was hentriacontene for females and nonacosene for males. The results obtained in this study are important for the establishment of a database to be used in chemotaxonomy of sanitarily and forensically important insects. 相似文献
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Patricia J. Lardone Amalia Rubio Isabel Cerrillo Araceli G��mez-Corvera Antonio Carrillo-Vico Marina Sanchez-Hidalgo Juan M. Guerrero Patricia Fernandez-Riejos Victor Sanchez-Margalet Patrocinio Molinero 《Cellular and molecular life sciences : CMLS》2010,67(18):3163-3172
Melatonin has been proposed as regulating the immune system by affecting cytokine production in immunocompetent cells, enhancing
the production of several T helper (Th)1 cytokines. To further investigate the melatonin’s role in IL-2/IL-2R system, we established
an inducible T-REx expression system in Jurkat cells in which the protein levels of HIOMT enzyme or MT1 receptor were significantly down-regulated upon tetracycline incubation. We found that T-REx Jurkat cells with lower levels
of HIOMT activity, and consequently lower content of endogenous melatonin, showed IL-2 production decrease after activation
with lectin. Likewise, tetracycline-inducible stable cell line expressing MT1 antisense produced decreased amounts of IL-2 (mRNA and protein levels) after stimulation. Moreover, in T-Rex-MT1 cells incubated with tetracycline, a sub-optimal PHA dose failed to induce the early activation marker CD25 on the cell surface.
The results shown here support the relevance of endogenous melatonin and its signaling in T cell activation. 相似文献