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71.
Kuroda T Suenaga K Sakakura A Handa T Okamoto K Kigoshi H 《Bioconjugate chemistry》2006,17(2):524-529
The interaction between actin and aplyronine A, a potent antitumor and actin-depolymerizing substance of marine origin, was investigated by photoaffinity labeling experiments. Photoaffinity probes consisting of a side-chain portion of aplyronine A as a ligand, a diazirine moiety as a photoaffinity group, and a fluorophore as a detecting group were synthesized. Photolabeling experiments between actin and the probe were carried out. Actin was successfully photolabeled by the fluorescent probe and visualized clearly. The present results provide the first chemical evidence for the direct interaction between actin and the side-chain portion of aplyronine A. 相似文献
72.
Takii M Ishikawa T Tsuda H Kanatani K Sunouchi T Kaneko Y Nakayama K 《American journal of physiology. Cell physiology》2006,291(6):C1405-C1411
In isolated rat pancreatic -cells, hypotonic stimulation elicited an increase in cytosolic Ca2+ concentration ([Ca2+]c) at 2.8 mM glucose. The hypotonically induced [Ca2+]c elevation was significantly suppressed by nicardipine, a voltage-dependent Ca2+ channel blocker, and by Gd3+, amiloride, 2-aminoethoxydiphenylborate, and ruthenium red, all cation channel blockers. In contrast, the [Ca2+]c elevation was not inhibited by suramin, a P2 purinoceptor antagonist. Whole cell patch-clamp analyses showed that hypotonic stimulation induced membrane depolarization of -cells and produced outwardly rectifying cation currents; Gd3+ inhibited both responses. Hypotonic stimulation also increased insulin secretion from isolated rat islets, and Gd3+ significantly suppressed this secretion. Together, these results suggest that osmotic cell swelling activates cation channels in rat pancreatic -cells, thereby causing membrane depolarization and subsequent activation of voltage-dependent Ca2+ channels and thus elevating insulin secretion. calcium ion; swelling; patch-clamp; gadolinium 相似文献
73.
Nucleoside diphosphate kinase (NDK) is a housekeeping enzyme localized in cellular organelles and distributed in various organs in prokaryotes and eukaryotes. In Neurospora crassa, NDK-1 is suggested to control catalases in response to heat, oxidative stress and light. In this study, we identified the presence of NDK-1 during most developmental stages in submerged mycelia, aerial hyphae, asexual conidia and perithecia, and the localization of it in soluble, mitochondrial, nuclear and membrane fractions in the mycelial cell. A light-dependent localization of NDK-1 was shown by Western blotting and immunohistochemical analysis using anti-NDK-1 antibody. In the mycelia, NDK-1 was compartmentalized on the plasma membrane in darkness, while it was relocated in the cytoplasm under light. These results suggest that NDK-1 protein was translocated from the plasma membrane to cytoplasm in response to light, and may interact with catalase. 相似文献
74.
Hirobe T Abe H 《Pigment cell research / sponsored by the European Society for Pigment Cell Research and the International Pigment Cell Society》2006,19(5):454-459
The slaty (Dct(slt)) mutation is known to reduce the activity of dopachrome tautomerase in melanocytes and to reduce the melanin content in skin, hairs and eyes. Although the melanosomes in slaty melanocytes are reported to be eumelanosome-like, detailed melanosome biogenesis is not well studied. To address this point, melanosomes in neonatal epidermal melanocytes from wild-type (Dct+/Dct+) mice at the slaty locus as well as its congenic mouse mutant (Dct(slt)/Dct(slt)) in serum-free primary culture were observed under the electron microscope. Wild-type melanocytes possessed exclusively elliptical melanosomes with internal longitudinal structures, whereas in mutant melanocytes, numerous spherical melanosomes with globular depositions of pigment and elliptical melanosomes as well as mixed type of the two melanosomes were observed. Mature stage IV melanosomes were greatly decreased in mutant melanocytes, whereas immature stage III melanosomes were more numerous than in wild-type melanocytes. These results suggest that the slaty mutation affects the morphology and maturation of melanosomes in mouse melanocytes. 相似文献
75.
Hasegawa T Umeda M Numata M Li C Bae AH Fujisawa T Haraguchi S Sakurai K Shinkai S 《Carbohydrate research》2006,341(1):35-40
(1-->3)-beta-D-Glucans having various functional appendages (lactoside, ferrocene, pyrene, and porphyrin) can be prepared in an convenient, quantitative, and regioselective manner through regioselective bromination-azidation of curdlan to afford 6-azido-6-deoxycurdlan followed by chemoselective [3+2]-cycloadditions with various functional modules bearing a terminal alkyne group. The ability to monitor reaction conversions is an additional advantage of this synthetic approach over the conventional direct modifications on polysaccharides; the reaction can be readily monitored based on the intensity of azido peaks in the in situ attenuated total reflection infrared spectra. 相似文献
76.
Masaaki Tanaka Norihiro Sadato Tomohisa Okada Kei Mizuno Tetsuya Sasabe Hiroki C Tanabe Daisuke N Saito Hirotaka Onoe Hirohiko Kuratsune Yasuyoshi Watanabe 《BMC neurology》2006,6(1):9
Background
Although the neural mechanism of chronic fatigue syndrome has been investigated by a number of researchers, it remains poorly understood. 相似文献77.
Furaquinocin is a natural polyketide-isoprenoid hybrid (meroterpenoid) produced by Streptomyces sp. strain KO-3988. All of the fur genes required for furaquinocin biosynthesis have been cloned, and the heterologous production of furaquinocin has been demonstrated in Streptomyces albus. Here, we report the identification of 8-amino-2,5,7-trihydroxynaphthalene-1,4-dione (8-amino-flaviolin) produced by the S. albus heterologous expression of the three contiguous genes encoding type III polyketide synthase (Fur1), monooxygenase (Fur2), and aminotransferase (Fur3) in the furaquinocin biosynthetic gene cluster. An S. albus transformant (S. albus/pWHM-Fur2_del3) harboring the fur gene cluster and lacking the fur3 gene did not produce furaquinocin, whereas furaquinocin production was restored when 8-amino-flaviolin was added to the culture medium of S. albus/pWHM-Fur2_del3. These results demonstrate that Fur3 aminotransferase is essential for furaquinocin biosynthesis and that 8-amino-flaviolin is an early-stage intermediate in furaquinocin biosynthesis. We propose that the biosynthetic pathway generating 8-amino-flaviolin is the common route for the biosynthesis of Streptomyces meroterpenoids. 相似文献
78.
Kuchimaru T Sato F Aoi Y Fujita T Ikeda T Shimizu K Kato Y Iida T 《Radiation and environmental biophysics》2008,47(4):535-540
To identify individual cells exposed to a X-ray microbeam in a cell population, we developed a biocompatible microchamber-array
chip using UV lithography of photopolymer SU-8. The center-to-center distance between microchambers is 50 μm including a wall
of 15 μm height. Using the microchamber-array chip, we performed tracking of individual exposed cells. Sample cells loaded
in a microchamber array were selectively irradiated with the X-ray microbeam under microscopic observation. All the irradiated
cells were indexed by the array arrangement of the microchambers. For about 24 h of post-irradiation incubation, the irradiated
cells were identified successfully by time-lapse observation. In addition, the induction of radiation effects was observed
in identified cells using immunofluorescence. 相似文献
79.
80.
Tomohisa Ogawa Tsuyoshi Shirai Clara Shionyu-Mitsuyama Takashi Yamane Hisao Kamiya Koji Muramoto 《Glycoconjugate journal》2002,19(7-9):451-458
Many cases of accelerated evolution driven by positive Darwinian selection are identified in the genes of venomous and reproductive proteins. This evolutional phenomenon might have important consequences in their gene-products' functions, such as multiple specific toxins for quick immobilization of the prey and the establishment of barriers to fertilization that might lead to speciation, and in the molecular evolution of novel genes. Recently, we analyzed the molecular evolution of two galectins isolated from the skin mucus of conger eel (Conger myriaster), named congerins I and II, by cDNA cloning and X-ray structural analysis, and we found that they have evolved in the rapid adaptive manner to emergence of a new structure including strand-swapping and a unique new ligand-binding site. In this review article we summarize and discuss the molecular evolution, especially the rapid adaptive evolution, and the structure-function relationships of conger eel galectins. Published in 2004. 相似文献