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41.
Keiichi Aritomo Chihiro Urashima Takeshi Wada Mitsuo Sekine 《Nucleosides, nucleotides & nucleic acids》2013,32(1-3):1-16
Abstract Reaction of 2′,3′,5′-O-silylated inosine derivative 1 with 2, 3-O-isopropylidene-5-O-tritylribosyl chloride (3) in a two-phase (CH2Cl2-aq. NaOH) system in the presence of Bu4NBr gave three products, i. e., 6-O-α-, 6-O-β-, and N 1-β-isomers of glycosides 4, 5a, and 5b. A similar PTC reaction of 1 with 2, 3, 5-tri-O-benzylribosyl bromide (9) gave four regio- and stereo-isomers involving the N1-β-glycoside 10. Reaction of 1 with 2, 3, 5-tri-O-benzoylribosyl bromide (11) afforded three products involving the desired N1-β-glycoside 12b, which could be deprotected to give N 1-ribosylinosine (15b) as a useful intermediate for the synthesis of cIDPR. 相似文献
42.
Yoshitaka Kaitsu Kiminori Shimizu Eiji Tanaka Satoshi Shimano Shigeru Uchiyama Chihiro Tanaka Noriko Kinjo 《Mycological Progress》2013,12(4):755-761
Ophiocordyceps sessilis, a new species of Ophiocordycipitaceae, Hypocreales, was found on Camponotus obscuripes ants, where the ants were primarily infected by another close relative, O. pulvinata. Morphological observation clearly indicated that O. sessilis and O. pulvinata are distinct species. Ophiocordyceps sessilis exhibited superficial development of perithecia and ascospore disarticulation into part-spores, not known in O. pulvinata. Nucleotide sequence data suggested that O. sessilis belongs in Ophiocordyceps, Ophiocordycipitaceae. Molecular data also indicated that O. sessilis is a close relative of O. cuboidea, O. prolifica, O. paracuboidea, and O. ryogamiensis, which are all known to produce part-spores. Since O. sessilis is always associated with ants infected by O. pulvinata, O. sessilis may be a hyperparasite of O. pulvinata. 相似文献
43.
44.
Mayumi Hachinohe Midori Yamane Daiki Akazawa Kazuhiro Ohsawa Mayumi Ohno Yuzu Terashita Hiroshi Masumoto 《PloS one》2013,8(1)
The regulation of energy metabolism, such as calorie restriction (CR), is a major determinant of cellular longevity. Although augmented gluconeogenesis is known to occur in aged yeast cells, the role of enhanced gluconeogenesis in aged cells remains undefined. Here, we show that age-enhanced gluconeogenesis is suppressed by the deletion of the tdh2 gene, which encodes glyceraldehyde-3-phosphate dehydrogenase (GAPDH), a protein that is involved in both glycolysis and gluconeogenesis in yeast cells. The deletion of TDH2 restores the chronological lifespan of cells with deletions of both the HST3 and HST4 genes, which encode yeast sirtuins, and represses the activation of gluconeogenesis. Furthermore, the tdh2 gene deletion can extend the replicative lifespan in a CR pathway-dependent manner. These findings demonstrate that the repression of enhanced gluconeogenesis effectively extends the cellular lifespan. 相似文献
45.
Chihiro Motozono John J. Miles Zafrul Hasan Hiroyuki Gatanaga Stanley C. Meribe David A. Price Shinichi Oka Andrew K. Sewell Takamasa Ueno 《PloS one》2013,8(6)
Antigen cross-reactivity is an inbuilt feature of the T cell compartment. However, little is known about the flexibility of T cell recognition in the context of genetically variable pathogens such as HIV-1. In this study, we used a combinatorial library containing 24 billion octamer peptides to characterize the cross-reactivity profiles of CD8+ T cells specific for the immunodominant HIV-1 subtype B Nef epitope VY8 (VPLRPMTY) presented by HLA-B*35∶01. In conjunction, we examined naturally occurring antigenic variations within the VY8 epitope. Sequence analysis of plasma viral RNA isolated from 336 HIV-1-infected individuals revealed variability at position (P) 3 and P8 of VY8; Phe at P8, but not Val at P3, was identified as an HLA-B*35∶01-associated polymorphism. VY8-specific T cells generated from several different HIV-1-infected patients showed unique and clonotype-dependent cross-reactivity footprints. Nonetheless, all T cells recognized both the index Leu and mutant Val at P3 equally well. In contrast, competitive titration assays revealed that the Tyr to Phe substitution at P8 reduced T cell recognition by 50–130 fold despite intact peptide binding to HLA-B*35∶01. These findings explain the preferential selection of Phe at the C-terminus of VY8 in HLA-B*35∶01+ individuals and demonstrate that HIV-1 can exploit the limitations of T cell recognition in vivo. 相似文献
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47.
Eita Uenishi Tadao Shibasaki Harumi Takahashi Chihiro Seki Hitomi Hamaguchi Takao Yasuda Masao Tatebe Yutaka Oiso Tadaomi Takenawa Susumu Seino 《The Journal of biological chemistry》2013,288(36):25851-25864
Actin dynamics in pancreatic β-cells is involved in insulin secretion. However, the molecular mechanisms of the regulation of actin dynamics by intracellular signals in pancreatic β-cells and its role in phasic insulin secretion are largely unknown. In this study, we elucidate the regulation of actin dynamics by neuronal Wiskott-Aldrich syndrome protein (N-WASP) and cofilin in pancreatic β-cells and demonstrate its role in glucose-induced insulin secretion (GIIS). N-WASP, which promotes actin polymerization through activation of the actin nucleation factor Arp2/3 complex, was found to be activated by glucose stimulation in insulin-secreting clonal pancreatic β-cells (MIN6-K8 β-cells). Introduction of a dominant-negative mutant of N-WASP, which lacks G-actin and Arp2/3 complex-binding region VCA, into MIN6-K8 β-cells or knockdown of N-WASP suppressed GIIS, especially the second phase. We also found that cofilin, which severs F-actin in its dephosphorylated (active) form, is converted to the phosphorylated (inactive) form by glucose stimulation in MIN6-K8 β-cells, thereby promoting F-actin remodeling. In addition, the dominant-negative mutant of cofilin, which inhibits activation of endogenous cofilin, or knockdown of cofilin reduced the second phase of GIIS. However, the first phase of GIIS occurs in the G-actin predominant state, in which cofilin activity predominates over N-WASP activity. Thus, actin dynamics regulated by the balance of N-WASP and cofilin activities determines the biphasic response of GIIS. 相似文献
48.
Kenji Sugimoto Kosuke Tamura Chihiro Tohda Naoki Toyooka Hideo Nemoto Yuji Matsuya 《Bioorganic & medicinal chemistry》2013,21(15):4459-4471
As an extended study on development of anti-Alzheimer’s disease agent, we newly synthesized various dihydrofuran-fused perhydrophenanthrenes via o-quinodimethane chemistry. This study revealed that the introduction of carbon side-chain on 8-position or removal of the acetal moiety on 3-position arose a cytotoxicity on rat cortical neurons. On the other hand, the ethereal or thio-ethereal substituent on 8-position enhanced the elongation effect on Aβ-damaged neurons. The necessity of the cyano group on 10b position was also proved in this structure–activity-relationship study. 相似文献
49.
Tetsuko Takabe Mikio Nishimtjra Takashi Akazawa 《Bioscience, biotechnology, and biochemistry》2013,77(10):2137-2142
The isolation of the photosynthetically competent chloroplast preparations was undertaken by means of the density gradient centrifugation on the modified silica sol “Percoll.” A clear separation of the intact chloroplast sustaining the high photosynthetic activities (light dependent CO2 fixation ca. 130μmol/mg Chl·hr) was established. The contamination of mitochondria and peroxisomes was estimated to be less than 3% by measuring the activities of their marker enzymes. The chloroplasts were proved to be free from endoplasmic reticulum and cytosol. The photosynthetic CO2 fixation of the isolated chloroplast preparations was saturated by illumination of the light intensity of 20,000 Lux (12 mW/cm2, 400~750 nm). 相似文献
50.
Takashi Akazawa Yasuichi Umemura Ikuzo Uritani 《Bioscience, biotechnology, and biochemistry》2013,77(3):192-196
It was shown in previous papers that in sweet potato infected with Ceratostomella fimbriata, there occurred metabolic activations such as respiratory increase, polyphenols production, protein synthesis and organic phosphate accumulation. In this report on an electrophoretic experiment, forming a part of those studies, it is stated that the pattern of the protein components in the sound part, adjacent to the infected part of sweet potato attacked by the pathogen differs from that of sound sweet potato. 相似文献