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排序方式: 共有452条查询结果,搜索用时 15 毫秒
121.
Ban R Takitani K Kim HS Murata T Morinobu T Ogihara T Tamai H 《Free radical research》2002,36(9):933-938
-Tochopherol transfer protein ( TTP), a 32 kDa protein exclusively expressed in liver cytosol, has a high binding affinity for -tochopherol. The factors that regulate the expression of hepatic TTP are not clearly understood. In this study, we investigated whether or not exposure to hyperoxia (95% O 2 for 48 h) could alter the expression of hepatic TTP. We also examined the association between the expression of antioxidant enzymes (hepatic glutathione peroxidase (GPX) and Mn-superoxide dismutase (Mn-SOD)) and the expression of hepatic TTP. The levels of thiobarbituric acid-reactive substances (TBARS) in both plasma and liver were significantly higher after rats were exposed to hyperoxia for 48 h when compared with the levels in control rats. Northern blotting showed a decrease in the expression of TTP messenger RNA (mRNA) after hyperoxia, although the TTP protein level remained constant. Expression of Mn-SOD mRNA and protein, as well as the expression of GPX mRNA, were stable after hyperoxia. These findings indicate that mRNA for hepatic TTP, rather than Mn-SOD or GPX, may be highly responsive to oxidative stress. 相似文献
122.
Using Cre/loxP, we conditionally inactivated the beta-catenin gene in cells of structures that exhibit important embryonic organizer functions: the visceral endoderm, the node, the notochord, and the definitive endoderm. Mesoderm formation was not affected in the mutant embryos, but the node was missing, patterning of the head and trunk was affected, and no notochord or somites were formed. Surprisingly, deletion of beta-catenin in the definitive endoderm led to the formation of multiple hearts all along the anterior-posterior (A/P) axis of the embryo. Ectopic hearts developed in parallel with the normal heart in regions of ectopic Bmp2 expression. We provide evidence that ablation of beta-catenin in embryonic endoderm changes cell fate from endoderm to precardiac mesoderm, consistent with the existence of bipotential mesendodermal progenitors in mouse embryos. 相似文献
123.
Yasushi Izumi Tomonori Hirose Yoko Tamai Syu-ichi Hirai Yoji Nagashima Toyoshi Fujimoto Yo Tabuse Kenneth J. Kemphues Shigeo Ohno 《The Journal of cell biology》1998,143(1):95-106
Cell polarity is fundamental to differentiation and function of most cells. Studies in mammalian epithelial cells have revealed that the establishment and maintenance of cell polarity depends upon cell adhesion, signaling networks, the cytoskeleton, and protein transport. Atypical protein kinase C (PKC) isotypes PKCζ and PKCλ have been implicated in signaling through lipid metabolites including phosphatidylinositol 3-phosphates, but their physiological role remains elusive. In the present study we report the identification of a protein, ASIP (atypical PKC isotype–specific interacting protein), that binds to aPKCs, and show that it colocalizes with PKCλ to the cell junctional complex in cultured epithelial MDCKII cells and rat intestinal epithelia. In addition, immunoelectron microscopy revealed that ASIP localizes to tight junctions in intestinal epithelial cells. Furthermore, ASIP shows significant sequence similarity to Caenorhabditis elegans PAR-3. PAR-3 protein is localized to the anterior periphery of the one-cell embryo, and is required for the establishment of cell polarity in early embryos. ASIP and PAR-3 share three PDZ domains, and can both bind to aPKCs. Taken together, our results suggest a role for a protein complex containing ASIP and aPKC in the establishment and/or maintenance of epithelial cell polarity. The evolutionary conservation of the protein complex and its asymmetric distribution in polarized cells from worm embryo to mammalian-differentiated cells may mean that the complex functions generally in the organization of cellular asymmetry. 相似文献
124.
The rice plant (Oryza sativa L. cv Oochikara) is known to be a Si accumulator, but the mechanism responsible for the high uptake of Si by the roots is not well understood. We investigated the role of root hairs and lateral roots in the Si uptake using two mutants of rice, one defective in the formation of root hairs (RH2) and another in that of lateral roots (RM109). Uptake experiments with nutrient solution during both a short term (up to 12 h) and relatively long term (26 d) showed that there was no significant difference in Si uptake between RH2 and the wild type (WT), whereas the Si uptake of RM109 was much less than that of WT. The number of silica bodies formed on the third leaf in RH2 was similar to that in WT, but the number of silica bodies in RM109 was only 40% of that in WT, when grown in soil amended with Si under flooded conditions. There was also no difference in the shoot Si concentration between WT and RH2 when grown in soil under upland conditions. Using a multi-compartment transport box, the Si uptake at the root tip (0-1 cm, without lateral roots and root hairs) was found to be similar in WT, RH2, and RM109. However, the Si uptake in the mature zone (1-4 cm from root tip) was significantly lower in RM109 than in WT, whereas no difference was found in Si uptake between WT and RH2. All these results clearly indicate that lateral roots contribute to the Si uptake in rice plant, whereas root hairs do not. Analysis of F(2) populations between RM109 and WT showed that Si uptake was correlated with the presence of lateral roots and that the gene controlling formation of lateral roots and Si uptake is a dominant gene. 相似文献
125.
Tomoko Sagai Tsuyoshi Koide Mori Endo Kenjiro Tanoue Yoshiaki Kikkawa Hiromichi Yonekawa Serichi Ishiguro Makoto Tamai Yoichi Matsuda Shigehora Wakana Toshihiko Shiroishi 《Mammalian genome》1998,9(1):2-7
A mouse mutation, rim2, is one of a series of spontaneous mutations that arose from the intra-MHC recombinants between Japanese wild mouse-derived
wm7 and laboratory MHC haplotypes. This mutation is single recessive and characterized by diluted coat color and hypo-pigmentation
of the eyes. We mapped the rim2 gene close to an old coat color mutation, pearl (pe), on Chromosome (Chr) 13 by the high-density linkage analysis. The pearl mutant is known to have abnormalities similar to
Hermansky-Pudlak syndrome (HPS), a human hemorrhagic disorder, characterized by albinism and storage pool deficiency (SPD)
of dense granules in platelets. A mating cross of C57BL10/Slc-rim2/rim2 and C57BL/6J-pe/pe showed no complementation of coat color. Additionally, characteristics similar to SPD were also observed in rim2. Thus, rim2 appeared to be a new allele of the pe locus and serves as a mouse model for human HPS. We have made a YAC contig covering the rim2/pe locus toward positional cloning of the causative gene.
Received: 23 July 1997 / Accepted: 26 August 1997 相似文献
126.
Mamoru Mimuro Tsunenori Nozawa Naoto Tamai Yoshinobu Nishimura Iwao Yamazaki 《FEBS letters》1994,340(3):167-172
Antenna components in the energy transfer processes of a green photosynthetic bacterium Chloroflexus aurantiacus were spectrally investigated by time-resolved fluorescence spectroscopy at −196°C on intact cells. Besides major antenna components so far reported, three minor components were resolved; those were Bchl c located at 785 nm, the baseplate Bchl a at 819 nm and Bchl a in the B808-866 complex at 910 nm. The last component was assigned to a longer wavelength antenna closely associated with a reaction center. An additional Bchl c fluorescence component was kinetically suggested to be present, which can be an energy donor to a major Bchl c. Presence of these minor components was signified in terms of (1) increase in the spectral overlap integral and (2) adjustment of the direction of dipole moments in the energy transfer sequence of intact cells. 相似文献
127.
Tadakazu Tamai Sanetaka Shirahata Nobuyuki Sato Shoji Kimura Michio Nonaka Hiroki Murakami 《Cytotechnology》1993,11(2):121-131
Flatfish leukocytes were transfected with the expression plasmids of the v-myc, c-myc, c-fos, v-myb and c-Ha-ras oncogenes. Only cotransfection of c-Ha-ras with c-myc or c-fos resulted in complete immortalization of the cells. Interferon-like anti-viral protein was found in the cultured medium of the immortalized lymphocytes. The protein was purified by DEAE-Toyopearl 650 M ion exchange chromatography and WGA agarose affinity chromatography. The protein was a glycoprotein of about 16 kDa. The antiviral activity of the protein was trypsin-sensitive and was fairly stable at pH values from 4 to 8. The protein retained about 60% of the activity even at 60°C and showed a broad antiviral activity for various fish cells and viruses. 相似文献
128.
129.
Characteristic distribution of glycolipids in gadoid fish nerve tissues and its bearing on phylogeny. 总被引:1,自引:0,他引:1
Glycolipids were isolated from nerve tissues of gadoid fishes including Alaskan pollack and Pacific cod. Their chemical structures were determined by gas-liquid chromatography and gas chromatography-mass spectrometry, and their constituents were analyzed in detail and compared with those of glycolipids from other fish groups. The results revealed that gadoid fish nerve membranes contain peculiar glycolipid molecular species that are distinctly different from those in other teleostean fishes and higher vertebrates. The mole percentage ratio of the four major glycolipids (cerebroside-sulfatide-galactosylglyceride-sulfogalactosylglyce ride) was 48:12:25:15, indicating profound accumulation of glycoglycerolipids. Galactosylglyceride and sulfogalactosylglyceride were primarily of the diacyl type (greater than 90%), the major fatty acids being 16:0 and 18:1. An abundance of glucocerebroside (25 to 55% of cerebroside) and its fatty acid ester (37 to 47% of ester cerebroside) was noted. Cerebroside and sulfatide were characterized by the absence of hydroxy and odd numbered fatty acids, and 24:1 acid was a predominant component of both glucocerebroside and galactocerebroside. Subcellular fractionation revealed that myelin membranes comprised such unusual glycolipid constituents as those seen in whole nerve tissues. A vertebrate whose nerve membranes consist of such peculiar glycolipid molecules has not previously been reported. The characteristics of the glycolipid composition in gadoid fishes are discussed in relation to myelin functions, physicochemical properties of nerve membranes, and the phylogenic significance of this fish group. 相似文献
130.
Interleukin-1 beta analogues with markedly reduced pyrogenic activity can stimulate secretion of adrenocorticotropic hormone in rats 总被引:1,自引:0,他引:1
Y Naito J Fukata Y Masui Y Hirai N Murakami T Tominaga Y Nakai S Tamai K Mori H Imura 《Biochemical and biophysical research communications》1990,167(1):103-109
We examined the adrenocorticotropic hormone-releasing activities of several human interleukin-1 beta analogues that have markedly reduced pyrogenic activities in rats. Among the analogues tested, [Gly4]-, [Leu93]- and [1-148]-interleukin-1 beta increased the plasma adrenocorticotropic hormone level to almost that induced by authentic human interleukin-1 beta. Modifications of the N-terminus of the authentic molecule, i.e., [7-153]- and [Des-Ala1, Asp4]-interleukin-1 beta, significantly reduced the hormone-releasing activity. These data suggest that the adrenocorticotropic hormone-releasing activity of human interleukin-1 beta resides in the N-terminal structure of the authentic peptide and can be separated from its pyrogenic activity. 相似文献