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441.
442.
Liu F Thirumangalathu S Gallant NM Yang SH Stoick-Cooper CL Reddy ST Andl T Taketo MM Dlugosz AA Moon RT Barlow LA Millar SE 《Nature genetics》2007,39(1):106-112
Fungiform taste papillae form a regular array on the dorsal tongue. Taste buds arise from papilla epithelium and, unusually for epithelial derivatives, synapse with neurons, release neurotransmitters and generate receptor and action potentials. Despite the importance of taste as one of our five senses, genetic analyses of taste papilla and bud development are lacking. We demonstrate that Wnt-beta-catenin signaling is activated in developing fungiform placodes and taste bud cells. A dominant stabilizing mutation of epithelial beta-catenin causes massive overproduction of enlarged fungiform papillae and taste buds. Likewise, genetic deletion of epithelial beta-catenin or inhibition of Wnt-beta-catenin signaling by ectopic dickkopf1 (Dkk1) blocks initiation of fungiform papilla morphogenesis. Ectopic papillae are innervated in the stabilizing beta-catenin mutant, whereas ectopic Dkk1 causes absence of lingual epithelial innervation. Thus, Wnt-beta-catenin signaling is critical for fungiform papilla and taste bud development. Altered regulation of this pathway may underlie evolutionary changes in taste papilla patterning. 相似文献
443.
Peutz-Jeghers syndrome (PJS, OMIM 175200) is an unusual inherited intestinal polyposis syndrome associated with distinct peri-oral
blue/black freckling [1–9]. Variable penetrance and clinical heterogeneity make it difficult to determine the exact frequency
of PJS [4]. PJS is a cancer predisposition syndrome. Affected individuals are at high risk for intestinal and extra-intestinal
cancers. In 1997, linkage studies mapped PJS to chromosome 19p [10, 11], and subsequently a serine/threonine kinase gene defect
(LKB1) was noted in a majority of PJS cases [12, 13]. A phenotypically similar syndrome has been produced in an LKB1 mouse
knockout model [14–18]. Several PJS kindred without LKB1 mutations have been described, suggesting other PJS loci [19–22].
The management of PJS is complex and evolving. New endoscopic technologies may improve management of intestinal polyposis.
Identification of specific genetic mutations and their targets will more accurately assess the clinical course, and help gage
the magnitude of cancer risk for affected individuals.
Received 20 February 2006; received after revision 5 May 2006; accepted 15 June 2006 相似文献
444.
Blasig IE Winkler L Lassowski B Mueller SL Zuleger N Krause E Krause G Gast K Kolbe M Piontek J 《Cellular and molecular life sciences : CMLS》2006,63(4):505-514
Tight junctions seal intercellular clefts via membrane-related strands, hence, maintaining important organ functions. We investigated
the self-association of strand-forming transmembrane tight junction proteins. The regulatory tight junction protein occludin
was differently tagged and cotransfected in eucaryotic cells. These occludins colocalized within the plasma membrane of the
same cell, coprecipitated and exhibited fluorescence resonance energy transfer. Differently tagged strand-forming claudin-5
also colocalized in the plasma membrane of the same cell and showed fluorescence resonance energy transfer. This demonstrates
self-association in intact cells both of occludin and claudin-5 in one plasma membrane. In search of dimerizing regions of
occludin, dimerization of its cytosolic C-terminal coiledcoil domain was identified. In claudin-5, the second extracellular
loop was detected as a dimer. Since the transmembrane junctional adhesion molecule also is known to dimerize, the assumption
that homodimerization of transmembrane tight junction proteins may serve as a common structural feature in tight junction
assembly is supported.
Received 6 October 2005; received after revision 14 December 2005; accepted 27 December 2005
†These authors contributed equally to this work. 相似文献
445.
Nodal signals pattern vertebrate embryos 总被引:4,自引:0,他引:4
Vertebrate embryonic patterning requires several conserved inductive signals–including Nodal, Bmp, Wnt and Fgf signals. Nodal,
which is a member of the transforming growth factor β (TGFβ) superfamily, activates a signal transduction pathway that is
similar to that of other TGFβ members. Nodal genes, which have been identified in numerous vertebrate species, are expressed
in specific cell types and tissues during embryonic development. Nodal signal transduction has been shown to play a pivotal
role in inducing and patterning mesoderm and endoderm, and in regulating neurogenesis and left-right axis asymmetry. Antagonists,
which act at different steps in the Nodal signal transduction pathway, have been shown to tightly modulate the inductive activity
of Nodal.
Received 20 October 2005; received after revision 15 November 2005; accepted 25 November 2005 相似文献
446.
Information processing along the course of a visual interneuron. 总被引:1,自引:0,他引:1
Locust ocellar retinal cells are innervated by giant second order cells, 2 mm long, which show discrete zones of integration along their course, including a major zone in the axonal length of the neuron. The complex synaptic arrangements which exist between higher-order afferent and efferent cells and these second order cells along their course suggests that transmission takes place by the electrotonic spread of slow potentials. The size and accessibility of these visual interneurons offers a unique preparation for examining mechanisms of graded synaptic transmission. 相似文献
447.
Ethanol, 3 g/kg i.p., did not significantly alter the acute toxicity of amphetamine in the mouse. However, the urinary metabolite pattern was changed, suggesting that ethanol suppressed metabolism of the stimulant during the initial 6 h period. After 24 h, the mouse metabolized the same fraction of a given dose of amphetamine, whether it was given as amphetamine alone or amphetamine mixed with 2,3 or 4 g/kg ethanol. 相似文献
448.
449.
传统的正向遗传学主要用于克隆表型或功能已确定的基因。转座子标签突变体可用随机标签法从带有活性转座子的自交后代中筛选得到,或用定向标签法从杂交一代中筛选得到,即用目的基因的隐性突变统合体与具高度活性转座号的统合体杂交,极大多数的FI个体为正常表型,但其中会有极少量的表现隐性性状的转庄子插入突变体。正向基因标签和克隆法在利用异源和低拷贝数品系时尤其有用。采用反向fCR或热不对称交替PCR(TAIL-PCR)且很容易从单拷贝或低拷贝数品系中获得插入于两侧的基因组序列。TAIL-PCR由三轮连续的半巢式PCR组成,所… 相似文献
450.
Relation between total and exchangeable sodium in the body 总被引:1,自引:0,他引:1