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排序方式: 共有73条查询结果,搜索用时 31 毫秒
1.
Summary Zn2+ (10–100 M) elevated the frequency of miniature end-plate potentials (MEPPs) in the mouse diaphragm. The effect did not depend on external Ca2+. Botulinum type A toxin (BTXA, 50 ng/ml) abolished MEPPs almost completely within 30 min. Zn2+ (100 M) restored MEPPs and increased their frequency after they had been abolished by BTXA in Ca2+-free solutions. The antagonistic effect of Zn2+ in the Ca2+-free solution was reduced by exposing the diaphragm to the toxin in the Ca2+-free solutions containing high K+. Thus, the action of BTXA is probably enhanced by depolarization of the motor nerve terminals. 相似文献
2.
3.
XinMiao Lü LiPing Zhu Mitsugu Nishimura Yoshimune Morita Takahiro Watanabe Toshio Nakamura Yong Wang 《科学通报(英文版)》2011,56(27):2931-2940
A 380-cm-long sediment core was acquired from the deep water area of Pumoyum Co, southern Tibet. Twenty-five plant residue
samples were selected, and organic carbon stable isotopes were obtained using the AMS 14C chronological method. The 14C age and carbon reservoir effect were calibrated with surface sedimentation rate measurements using 210Pb dating. Results showed that the core sediment deposited over 19 cal ka BP. Based on a multi-proxy analysis of TOC and IC
contents, grain size and pollen assemblage data, the palaeoclimatic evolution of Pumoyum Co was reconstructed since the last
glacial. Pumoyum Co was a shallow lake prior to 16.2 cal ka BP; although the glacier around the lake began to melt due to
increasing temperatures, climate was still cold and dry. In the interval of 16.2–11.8 cal ka BP, the sedimentary environment
fluctuated drastically and frequently. Two cold-events occurred at 14.2 and 11.8 cal ka BP, and these may correspond to the
Older Dryas and the Younger Dryas events, respectively. After 11.8 cal ka BP, Pumoyun Co developed into the deep lake as it
is now. The lake water temperature was relatively lower at that time because of influx of cold water from glacial meltwater
entering the lake. As a result, the multi-proxy indicators showed no sign of warm conditions. Comparisons between the sedimentary
record of Pumoyum Co with that of other lakes of the same age in southern Tibet indicate a warmer climate following the last
deglaciation influenced the southeastern Tibetan Plateau. These results imply that the southwest Asian monsoon gradually became
stronger since the deglaciation during its expansion to the inner plateau. The glacial-supplied water of the lake responded
sensitively to cold-events. The entire southern Tibet region was dominantly influenced climatically by the southwest Asian
monsoon during the Holocene. 相似文献
4.
T. Horio Y. Kawabata T. Takayama S. Tahara J. Kawabata Y. Fukushi H. Nishimura J. Mizutani 《Cellular and molecular life sciences : CMLS》1992,48(4):410-414
A highly potent attractant of zoospores ofAphanomyces cochlioides, a causal fungus of the root rot disease of spinach (Spinacia oleracea), was isolated from spinach roots, and its structure was determined by spectroscopic evidence and chemical synthesis as cochliophilin A (5-hydroxy-6,7-methylenedioxyflavone,1). A chromosorb particle prepared by soaking in solution of1 showed a potent attracting activity toward the zoospores using concentrations of1 above 10–9 or 10–10 M. 相似文献
5.
Metastasis suppressor gene KiSS-1 encodes peptide ligand of a G-protein-coupled receptor 总被引:72,自引:0,他引:72
Ohtaki T Shintani Y Honda S Matsumoto H Hori A Kanehashi K Terao Y Kumano S Takatsu Y Masuda Y Ishibashi Y Watanabe T Asada M Yamada T Suenaga M Kitada C Usuki S Kurokawa T Onda H Nishimura O Fujino M 《Nature》2001,411(6837):613-617
Metastasis is a major cause of death in cancer patients and involves a multistep process including detachment of cancer cells from a primary cancer, invasion of surrounding tissue, spread through circulation, re-invasion and proliferation in distant organs. KiSS-1 is a human metastasis suppressor gene, that suppresses metastases of human melanomas and breast carcinomas without affecting tumorigenicity. However, its gene product and functional mechanisms have not been elucidated. Here we show that KiSS-1 (refs 1, 4) encodes a carboxy-terminally amidated peptide with 54 amino-acid residues, which we have isolated from human placenta as the endogenous ligand of an orphan G-protein-coupled receptor (hOT7T175) and have named 'metastin'. Metastin inhibits chemotaxis and invasion of hOT7T175-transfected CHO cells in vitro and attenuates pulmonary metastasis of hOT7T175-transfected B16-BL6 melanomas in vivo. The results suggest possible mechanisms of action for KiSS-1 and a potential new therapeutic approach. 相似文献
6.
Nicastrin modulates presenilin-mediated notch/glp-1 signal transduction and betaAPP processing 总被引:26,自引:0,他引:26
Yu G Nishimura M Arawaka S Levitan D Zhang L Tandon A Song YQ Rogaeva E Chen F Kawarai T Supala A Levesque L Yu H Yang DS Holmes E Milman P Liang Y Zhang DM Xu DH Sato C Rogaev E Smith M Janus C Zhang Y Aebersold R Farrer LS Sorbi S Bruni A Fraser P St George-Hyslop P 《Nature》2000,407(6800):48-54
Nicastrin, a transmembrane glycoprotein, forms high molecular weight complexes with presenilin 1 and presenilin 2. Suppression of nicastrin expression in Caenorhabditis elegans embryos induces a subset of notch/glp-1 phenotypes similar to those induced by simultaneous null mutations in both presenilin homologues of C. elegans (sel-12 and hop-1). Nicastrin also binds carboxy-terminal derivatives of beta-amyloid precursor protein (betaAPP), and modulates the production of the amyloid beta-peptide (A beta) from these derivatives. Missense mutations in a conserved hydrophilic domain of nicastrin increase A beta42 and A beta40 peptide secretion. Deletions in this domain inhibit A beta production. Nicastrin and presenilins are therefore likely to be functional components of a multimeric complex necessary for the intramembranous proteolysis of proteins such as Notch/GLP-1 and betaAPP. 相似文献
7.
E A Rogaeva S Premkumar J Grubber L Serneels W K Scott T Kawarai Y Song D L Hill S M Abou-Donia E R Martin J J Vance G Yu A Orlacchio Y Pei M Nishimura A Supala B Roberge A M Saunders A D Roses D Schmechel A Crane-Gatherum S Sorbi A Bruni G W Small P M Conneally J L Haines F Van Leuven P H St George-Hyslop L A Farrer M A Pericak-Vance 《Nature genetics》1999,22(1):19-22
8.
9.
L A Tong A M de Vos M V Milburn J Jancarik S Noguchi S Nishimura K Miura E Ohtsuka S H Kim 《Nature》1989,337(6202):90-93
One of the most commonly found transforming ras oncogenes in human tumours has a valine codon replacing the glycine codon at position 12 of the normal c-Ha-ras gene. To understand the structural reasons behind cell transformation arising from this single amino acid substitution, we have determined the crystal structure of the GDP-bound form of the mutant protein, p21(Val-12), encoded by this oncogene. We report here the overall structure of p21(Val-12) at 2.2 A resolution and compare it with the structure of the normal c-Ha-ras protein. One of the major differences is that the loop of the transforming ras protein that binds the beta-phosphate of the guanine nucleotide is enlarged. Such a change in the 'catalytic site' conformation could explain the reduced GTPase activity of the mutant, which keeps the protein in the GTP bound 'signal on' state for a prolonged period time, ultimately causing cell transformation. 相似文献
10.
Saitsu H Kato M Mizuguchi T Hamada K Osaka H Tohyama J Uruno K Kumada S Nishiyama K Nishimura A Okada I Yoshimura Y Hirai S Kumada T Hayasaka K Fukuda A Ogata K Matsumoto N 《Nature genetics》2008,40(6):782-788
Early infantile epileptic encephalopathy with suppression-burst (EIEE), also known as Ohtahara syndrome, is one of the most severe and earliest forms of epilepsy. Using array-based comparative genomic hybridization, we found a de novo 2.0-Mb microdeletion at 9q33.3-q34.11 in a girl with EIEE. Mutation analysis of candidate genes mapped to the deletion revealed that four unrelated individuals with EIEE had heterozygous missense mutations in the gene encoding syntaxin binding protein 1 (STXBP1). STXBP1 (also known as MUNC18-1) is an evolutionally conserved neuronal Sec1/Munc-18 (SM) protein that is essential in synaptic vesicle release in several species. Circular dichroism melting experiments revealed that a mutant form of the protein was significantly thermolabile compared to wild type. Furthermore, binding of the mutant protein to syntaxin was impaired. These findings suggest that haploinsufficiency of STXBP1 causes EIEE. 相似文献