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112.
Yan Li Xiaoyu Wang Zhenglai Ma Manli Chuai Andrea Münsterberg Kenneth KaHo Lee Xuesong Yang 《科学通报(英文版)》2014,59(22):2749-2755
Heart formation commences from a single heart tube, which fuses from bilateral primordial heart fields. The developing heart tube is composed of outerlayer myocardial cells and innerlayer endocardial cells. Several distinct populations of precardiac cells contribute to cardiac morphogenesis. However, it still remains not very clear about the lineage of endocardium at gastrulation stage. Thereby, this study focused on ascertaining the correlation between the hypoblast in gastrulation and endocardium during cardiogenesis. Firstly, the fusing heart tube morphologically is closed to endoderm-derived pharynx floor, implying the possibility that pharynx floor might be wrapped into the formation of endoderm. Secondly, HNK1 is expressed in hypoblast strongly at gastrula stage and subsequently appeared in endocardium of cardiogenesis. Moreover, fate map data displayed that DiI labeled hypoblast was also present in endocardium later on. One more evidence is chickquail chimera of hypoblast transplantation, in which quailhypoblast derivative could be identified in endocardium of cardiogenesis by QCPN antibody. In sum, our current data suggests that endoderrn in gastrula contribute at least partly to the formation of endocardium of cardiogenesis. 相似文献
113.
Alushin GM Ramey VH Pasqualato S Ball DA Grigorieff N Musacchio A Nogales E 《Nature》2010,467(7317):805-810
The Ndc80 complex is a key site of regulated kinetochore-microtubule attachment (a process required for cell division), but the molecular mechanism underlying its function remains unknown. Here we present a subnanometre-resolution cryo-electron microscopy reconstruction of the human Ndc80 complex bound to microtubules, sufficient for precise docking of crystal structures of the component proteins. We find that the Ndc80 complex binds the microtubule with a tubulin monomer repeat, recognizing α- and β-tubulin at both intra- and inter-tubulin dimer interfaces in a manner that is sensitive to tubulin conformation. Furthermore, Ndc80 complexes self-associate along protofilaments through interactions mediated by the amino-terminal tail of the NDC80 protein, which is the site of phospho-regulation by Aurora B kinase. The complex's mode of interaction with the microtubule and its oligomerization suggest a mechanism by which Aurora B could regulate the stability of load-bearing kinetochore-microtubule attachments. 相似文献
114.
Beck PG Montalban J Kallinger T De Ridder J Aerts C García RA Hekker S Dupret MA Mosser B Eggenberger P Stello D Elsworth Y Frandsen S Carrier F Hillen M Gruberbauer M Christensen-Dalsgaard J Miglio A Valentini M Bedding TR Kjeldsen H Girouard FR Hall JR Ibrahim KA 《Nature》2012,481(7379):55-57
When the core hydrogen is exhausted during stellar evolution, the central region of a star contracts and the outer envelope expands and cools, giving rise to a red giant. Convection takes place over much of the star's radius. Conservation of angular momentum requires that the cores of these stars rotate faster than their envelopes; indirect evidence supports this. Information about the angular-momentum distribution is inaccessible to direct observations, but it can be extracted from the effect of rotation on oscillation modes that probe the stellar interior. Here we report an increasing rotation rate from the surface of the star to the stellar core in the interiors of red giants, obtained using the rotational frequency splitting of recently detected 'mixed modes'. By comparison with theoretical stellar models, we conclude that the core must rotate at least ten times faster than the surface. This observational result confirms the theoretical prediction of a steep gradient in the rotation profile towards the deep stellar interior. 相似文献
115.
Harris TH Banigan EJ Christian DA Konradt C Tait Wojno ED Norose K Wilson EH John B Weninger W Luster AD Liu AJ Hunter CA 《Nature》2012,486(7404):545-548
Chemokines have a central role in regulating processes essential to the immune function of T cells, such as their migration within lymphoid tissues and targeting of pathogens in sites of inflammation. Here we track T cells using multi-photon microscopy to demonstrate that the chemokine CXCL10 enhances the ability of CD8+ T cells to control the pathogen Toxoplasma gondii in the brains of chronically infected mice. This chemokine boosts T-cell function in two different ways: it maintains the effector T-cell population in the brain and speeds up the average migration speed without changing the nature of the walk statistics. Notably, these statistics are not Brownian; rather, CD8+ T-cell motility in the brain is well described by a generalized Lévy walk. According to our model, this unexpected feature enables T cells to find rare targets with more than an order of magnitude more efficiency than Brownian random walkers. Thus, CD8+ T-cell behaviour is similar to Lévy strategies reported in organisms ranging from mussels to marine predators and monkeys, and CXCL10 aids T cells in shortening the average time taken to find rare targets. 相似文献
116.
Transmission of obligate bacterial symbionts between generations is vital for the survival of the host. Although the larvae of certain hydrothermal vent tubeworms (Vestimentifera, Siboglinidae) are symbiont-free and possess a transient digestive system, these structures are lost during development, resulting in adult animals that are nutritionally dependent on their bacterial symbionts. Thus, each generation of tubeworms must be newly colonized with its specific symbiont. Here we present a model for tubeworm symbiont acquisition and the development of the symbiont-housing organ, the trophosome. Our data indicate that the bacterial symbionts colonize the developing tube of the settled larvae and enter the host through the skin, a process that continues through the early juvenile stages during which the trophosome is established from mesodermal tissue. In later juvenile stages we observed massive apoptosis of host epidermis, muscles and undifferentiated mesodermal tissue, which was coincident with the cessation of the colonization process. Characterizing the symbiont transmission process in this finely tuned mutualistic symbiosis provides another model of symbiont acquisition and additional insights into underlying mechanisms common to both pathogenic infections and beneficial host-symbiont interactions. 相似文献
117.
Bild AH Yao G Chang JT Wang Q Potti A Chasse D Joshi MB Harpole D Lancaster JM Berchuck A Olson JA Marks JR Dressman HK West M Nevins JR 《Nature》2006,439(7074):353-357
The development of an oncogenic state is a complex process involving the accumulation of multiple independent mutations that lead to deregulation of cell signalling pathways central to the control of cell growth and cell fate. The ability to define cancer subtypes, recurrence of disease and response to specific therapies using DNA microarray-based gene expression signatures has been demonstrated in multiple studies. Various studies have also demonstrated the potential for using gene expression profiles for the analysis of oncogenic pathways. Here we show that gene expression signatures can be identified that reflect the activation status of several oncogenic pathways. When evaluated in several large collections of human cancers, these gene expression signatures identify patterns of pathway deregulation in tumours and clinically relevant associations with disease outcomes. Combining signature-based predictions across several pathways identifies coordinated patterns of pathway deregulation that distinguish between specific cancers and tumour subtypes. Clustering tumours based on pathway signatures further defines prognosis in respective patient subsets, demonstrating that patterns of oncogenic pathway deregulation underlie the development of the oncogenic phenotype and reflect the biology and outcome of specific cancers. Predictions of pathway deregulation in cancer cell lines are also shown to predict the sensitivity to therapeutic agents that target components of the pathway. Linking pathway deregulation with sensitivity to therapeutics that target components of the pathway provides an opportunity to make use of these oncogenic pathway signatures to guide the use of targeted therapeutics. 相似文献
118.
Touch sensitivity in animals relies on nerve endings in the skin that convert mechanical force into electrical signals. In the nematode Caenorhabditis elegans, gentle touch to the body wall is sensed by six mechanosensory neurons that express two amiloride-sensitive Na+ channel proteins (DEG/ENaC). These proteins, MEC-4 and MEC-10, are required for touch sensation and can mutate to cause neuronal degeneration. Here we show that these mutant or 'd' forms of MEC-4 and MEC-10 produce a constitutively active, amiloride-sensitive ionic current when co-expressed in Xenopus oocytes, but not on their own. MEC-2, a stomatin-related protein needed for touch sensitivity, increased the activity of mutant channels about 40-fold and allowed currents to be detected with wild-type MEC-4 and MEC-10. Whereas neither the central, stomatin-like domain of MEC-2 nor human stomatin retained the activity of full-length MEC-2, both produced amiloride-sensitive currents with MEC-4d. Our findings indicate that MEC-2 regulates MEC-4/MEC-10 ion channels and raise the possibility that similar ion channels may be formed by stomatin-like proteins and DEG/ENaC proteins that are co-expressed in both vertebrates and invertebrates. Some of these channels may mediate mechanosensory responses. 相似文献
119.
Opposite thermosensor in fruitfly and mouse 总被引:1,自引:0,他引:1
Viswanath V Story GM Peier AM Petrus MJ Lee VM Hwang SW Patapoutian A Jegla T 《Nature》2003,423(6942):822-823
120.