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Hokkaido University Collection of Scholarly and Academic Papers (135.711 recursos)

HUSCAP (Hokkaido University Collection of Scholarly and Academic Papers) contains peer-reviewed journal articles, proceedings, educational resources and any kind of scholarly works of Hokkaido University.

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Mostrando recursos 1 - 20 de 1.171

  1. Enantiocontrol by assembled attractive interactions in copper-catalyzed asymmetric direct alkynylation of alpha-ketoesters with terminal alkynes: OH center dot center dot center dot O/sp(3)-CH center dot center dot center dot O two-point hydrogen bonding

    Schwarzer, Martin C.; Fujioka, Akane; Ishii, Takaoki; Ohmiya, Hirohisa; Mori, Seiji; Sawamura, Masaya
    Copper-catalyzed asymmetric direct alkynylation of alpha-ketoesters with terminal alkynes with chiral prolinol-phosphine ligands, most preferably (alpha R, 2S)-1-(2-dicyclohexylphosphinobenzyl)-alpha-neopentyl-2-pyrrolidinemethanol, afforded various enantioenriched chiral propargylic tertiary alcohols. Quantumchemical calculations using the BP86 density functional including Grimme's empirical dispersion correction [DF-BP86-D3(BJ)-PCM(tBuOH)/TZVPP//DF-BP86-D3(BJ)/SVP] show the occurrence of OH center dot center dot center dot O/sp(3)-CH center dot center dot center dot O two-point hydrogen bonding between the chiral ligand and the carbonyl group of the ketoester in the stereo-determining transition states. Combined with the hydrogen-bonding interactions orienting the ketoester substrate, dispersive attractions between the chiral ligand (P-cyclohexyl groups) and the ketoester in the favored transition...

  2. Enhanced circular dichroism at elevated temperatures through complexation-induced transformation of a three-layer cyclophane with dualistic dynamic helicity

    Katoono, Ryo; Obara, Yudai; Fujiwara, Kenshu; Suzuki, Takanori
    When two planes stacked one above the other are twisted, they provide a dynamic pair of helical conformations with (M)- or (P)-helicity. We designed a three-layer cyclophane that consists of two such dynamic pairs: the top and middle planes, and the middle and bottom planes. Hence, several global conformations could be created for the overall molecule, e.g., double-helical forms with a pair with the same helicity [(M, M) or (P, P)], and a meso-like form with a pair with a different helicity (M, P). These conformations dynamically interconvert to each other in solution. Chiroptical properties were given by the helical-sense...

  3. Real-time imaging of actin filaments in the zebrafish oocyte and embryo

    Nukada, Yumiko; Horie, Mayu; Fukui, Akimasa; Kotani, Tomoya; Yamashita, Masakane
    Dynamic changes of cytoplasmic and cortical actin filaments drive various cellular and developmental processes. Although real-time imaging of actin filaments in living cells has been developed, imaging of actin filaments in specific cells of living organisms remains limited, particularly for the analysis of gamete formation and early embryonic development. Here, we report the production of transgenic zebrafish expressing the C-terminus of Moesin, an actin filament-binding protein, fused with green fluorescent protein or red fluorescent protein (GFP/RFP-MoeC), under the control of a cyclin B1 promoter. GFP/RFP-MoeC was expressed maternally, which labels the cortical actin cytoskeleton of blastula-stage cells. High levels of...

  4. High-Sensitivity and High-Resolution In Situ Hybridization of Coding and Long Non-coding RNAs in Vertebrate Ovaries and Testes

    Takei, Natsumi; Nakamura, Takuma; Kawamura, Shohei; Takada, Yuki; Satoh, Yui; Kimura, Atsushi P.; Kotani, Tomoya
    Background: Subcellular localization of coding and non-coding RNAs has emerged as major regulatory mechanisms of gene expression in various cell types and many organisms. However, techniques that enable detection of the subcellular distribution of these RNAs with high sensitivity and high resolution remain limited, particularly in vertebrate adult tissues and organs. In this study, we examined the expression and localization of mRNAs encoding Pou5f1/Oct4, Mos, Cyclin B1 and Deleted in Azoospermia-like (Dazl) in zebrafish and mouse ovaries by combining tyramide signal amplification (TSA)-based in situ hybridization with paraffin sections which can preserve cell morphology of tissues and organs at subcellular...

  5. Characterization of a heat-activated retrotransposon in Vigna angularis

    Masuta, Yukari; Kawabe, Akira; Nozawa, Kosuke; Naito, Ken; Kato, Atsushi; Ito, Hidetaka
    In plants, several transposable elements are conserved across species. We found a homolog of ONSEN, which is a heat-activated retrotransposon originally isolated from Arabidopsis thaliana, in Vigna. The ONSEN-like elements (VaONS) were detected in all the analyzed Japanese accessions of Vigna angularis (adzuki bean) by Southern blot analysis. However, VaONS sequences were observed to be polymorphic in the different accessions. Interestingly, extrachromosomal DNA (ecDNA) was detected in some accessions of adzuki bean, indicating the conserved heat-activation of VaONS. Furthermore, we successfully induced retrotransposition of VaONS in adzuki plant regenerated through callus. Findings of our study should provide a new tool for molecular breeding of adzuki bean.

  6. Asymmetric Synthesis of beta-Lactams through Copper-Catalyzed Alkyne-Nitrone Coupling with a Prolinol-Phosphine Chiral Ligand

    Takayama, Yurie; Ishii, Takaoki; Ohmiya, Hirohisa; Iwai, Tomohiro; Schwarzer, Martin C.; Mori, Seiji; Taniguchi, Tohru; Monde, Kenji; Sawamura, Masaya
    Prolinol-phosphine chiral ligands enabled highly enantioselective copper-catalyzed intermolecular alkyne-nitrone coupling (Kinugasa reaction) to produce 1,3,4-trisubstituted chiral beta-lactams. A high level of enantiocontrol was achieved not only with aryl-or alkenylacetylenes but also with alkylacetylenes, which were important but unfavorable substrates in the previously reported protocols. Two-point hydrogen bonding between the chiral ligand and the nitrone oxyanion consisting of O-H center dot center dot center dot O and C(sp(3)) H center dot center dot center dot O hydrogen bonds is proposed.

  7. Low Genetic Variation of Red-crowned Cranes on Hokkaido Island, Japan, Over the Hundred Years

    Akiyama, Takuya; Momose, Kunikazu; Onuma, Manabu; Matsumoto, Fumio; Masuda, Ryuichi
    The red-crowned crane (Grus japonensis) is recognized internationally as an endangered species. Migratory populations breed in eastern Russia and northeastern China, whereas the resident population inhabits the island of Hokkaido, Japan. Although the population inhabiting Hokkaido had experienced a severe bottleneck by the end of the 19th century, the population size has recovered to about 1500 and continues to increase now thanks to conservation efforts. A previous study reported that no marked genetic differences were seen in the island population, and that the genetic variation of the whole population on Hokkaido was lower than that of the continental population. However,...

  8. Semi-retentive cytoskeletal fractionation (SERCYF): A novel method for the biochemical analysis of the organization of microtubule and actin cytoskeleton networks

    Sato, Yuta; Murakami, Yota; Takahashi, Masayuki
    A variety of biochemical fractionation methods are available for the quantification of cytoskeletal components. However, each method is designed to target only one cytoskeletal network, either the micro tubule (MT) or actin cytoskeleton, and non-targeted cytoskeletal networks are ignored. Considering the importance of MT actin crosstalk, the organization of both the targeted and non-targeted cytoskeletal networks must be retained intact during fractionation for the accurate analysis of cytoskeletal organization. In this study, we reveal that existing fractionation methods, represented by the MT sedimentation-method for MTs and the Triton X-100 solubility assay-method for actin cytoskeletons, disrupt the organizations of the non-targeted...

  9. ホンビノスガイ漁業の発展過程から考える東京湾における人と生物と水の関係

    濱崎, 瑠菜; 工藤, 貴史

  10. Role of the d-d interaction in the antiferromagnetic phase of lambda-(BEDT-STF)(2)FeCl4

    Minamidate, Takaaki; Shindo, Hironori; Ihara, Yoshihiko; Kawamoto, Atsushi; Matsunaga, Noriaki; Nomura, Kazushige
    Magnetic susceptibility and proton nuclear magnetic resonance (H-1-NMR) measurements were performed for the quasi-two-dimensional pi-d interacting system lambda-(BEDT-STF)(2)FeCl4 at ambient pressure. Magnetic susceptibility arising from the 3d spins of the FeCl4 anion show an anisotropy at low temperature and its temperature dependence for the external field parallel to the c axis is described as a broad peak structure at 8 K. A sharp peak in the temperature dependence of T-1(-1) associated with the antiferromagnetic (AF) transition is observed at T-AF = 16 K, together with the drastic splitting of the NMR spectrum below T-AF. The relation between the static susceptibility...

  11. Iron chelators inhibit the heme-degradation reaction by HutZ from Vibrio cholerae

    Dojun, Nobuhiko; Sekine, Yukari; Ishimori, Koichiro; Uchida, Takeshi
    HutZ is a heme-degrading enzyme. We found that the heme-degradation reaction by HutZ is inhibited by the iron chelators. Kinetic analysis of each heme-degradation step suggests that water molecules hydrogen bonded to Thr27 are involved in proton transfer to Fe(III)-OO-, and that this step is inhibited by iron chelators.

  12. Two Perturbations for Geometry Optimization of Off-Lattice Bead Protein Models

    Takeuchi, Hiroshi
    Referring to the optimization algorithm previously developed for atomic clusters, the present author develops an efficient method for geometry optimization of a coarse‐grained protein model expressed with two kinds of beads (hydrophilic and hydrophobic ones). In the method, two types of geometrical perturbations, center‐directed bead move and one bead rotation, are used to explore new configurations and local optimizations are performed after the perturbations. The center‐directed bead move is used for hydrophobic beads and the one bead rotation is performed for both hydrophobic and hydrophilic beads. The optimization method was applied to protein models consisting of 13, 20, 21, and...

  13. Theoretical and numerical analysis of a heat pump model utilizing Dufour effect

    Hoshina, Minoru; Okuda, Koji
    A heat pump model utilizing the Dufour effect is proposed, and studied by numerical and theoretical analysis. Numerically, we perform MD simulations of this system and measure the cooling power and the coefficient of performance (COP) as figures of merit. Theoretically, we calculate the cooling power and the COP from the phenomenological equations describing this system by using the linear irreversible thermodynamics and compare the theoretical results with the MD results.

  14. Past summer upwelling events in the Gulf of Oman derived from a coral geochemical record

    Watanabe, Takaaki K.; Watanabe, Tsuyoshi; Yamazaki, Atsuko; Pfeiffer, Miriam; Garbe-Schoenberg, Dieter; Claereboudt, Michel R.
    We used a high-resolution oxygen isotope (delta O-18(coral)), carbon isotope (delta O-18(coral)) and Sr/Ca ratios measured in the skeleton of a reef-building coral, Porites sp., to reveal seasonal-scale upwelling events and their interannual variability in the Gulf of Oman. Our delta C-13(coral) record shows sharp negative excursions in the summer, which correlate with known upwelling events. Using delta C-13(coral) anomalies as a proxy for upwelling, we found 17 summer upwelling events occurred in the last 26 years. These anomalous negative excursions of delta C-13(coral) result from upwelled water depleted in C-13 (dissolved inorganic carbon) and decreased water-column transparency. We reconstructed...

  15. Sensitivity of Clay Suspension Rheological Properties to pH, Temperature, Salinity, and Smectite-Quartz Ratio

    Kameda, Jun; Morisaki, Tomonori
    Understanding the rheological properties of clay suspensions is critical to assessing the behavior of sediment gravity flows such as debris flow or turbidity current. We conducted rheological measurements of composite smectite-quartz suspensions at a temperature of 7 degrees C and a salt concentration of 0.6M. This is representative of smectite-bearing sediments under conditions on the seafloor. The flow curves obtained were fitted by the Bingham fluid model, from which we determined the Bingham yield stress and dynamic viscosity of each suspension. At a constant smectite-quartz mixing ratio, the yield stress and the dynamic viscosity tend to increase as the solid/water...

  16. Involvement of the nuclear progestin receptor in LH-induced expression of membrane type 2-matrix metalloproteinase required for follicle rupture during ovulation in the medaka, Oryzias latipes

    Ogiwara, Katsueki; Takahashi, Takayuki
    Hormonal regulation of the expression of Mmp15, a proteolytic enzyme indispensable for ovulation in the teleost medaka, was investigated. In an in vitro culture system using preovulatory follicles, Mmp15 expression and ovulation were induced in the presence of recombinant luteinizing hormone (rLh). Both rLh-induced Mmp15 expression and ovulation were 17 alpha, 20 beta-dihydroxy-4-pregnen-3-one-dependent, suggesting the involvement of a nuclear progestin receptor (Pgr). In vitro follicle ovulation and Mmp15 expression were reduced by treatment with the Pgr antagonist RU-486. Like Pgr, the transcription factor CCAAT/enhancer-binding protein beta (Cebpb) was induced by rLh. ChIP analyses indicated that Pgr and Cebpb bound to...

  17. Tsunami Simulation Method Assimilating Ocean Bottom Pressure Data Near a Tsunami Source Region

    Tanioka, Yuichiro
    A new method was developed to reproduce the tsunami height distribution in and around the source area, at a certain time, from a large number of ocean bottom pressure sensors, without information on an earthquake source. A dense cabled observation network called S-NET, which consists of 150 ocean bottom pressure sensors, was installed recently along a wide portion of the seafloor off Kanto, Tohoku, and Hokkaido in Japan. However, in the source area, the ocean bottom pressure sensors cannot observe directly an initial ocean surface displacement. Therefore, we developed the new method. The method was tested and functioned well for...

  18. Interseismic crustal deformation in and around the Atotsugawa fault system, central Japan, detected by InSAR and GNSS

    Takada, Youichiro; Sagiya, Takeshi; Nishimura, Takuya
    The Atotsugawa fault system is one of the best-known active faults in Japan. However, revealing the interseismic velocity field in and around the Atotsugawa fault system with high spatial resolution is challenging because of dense vegetation, steep topography, and heavy snowfall in winter. To overcome these difficulties, we combined ALOS/PALSAR data and GNSS data from our original stations in addition to the nationwide station network (GEONET). First, we removed the height-dependent phase change in each interferogram using a digital elevation model. Next, we removed the long-wavelength phase trend using the GNSS velocity field. Finally, we applied an InSAR time-series analysis,...

  19. A new species of the rare, deep-sea polychaete genus Benthoscolex from the Sea of Kumano, Japan (Annelida, Amphinomidae)

    Jimi, Naoto; Kimura, Taeko; Ogawa, Akito; Kajihara, Hiroshi
    A new species of amphinomid polychaete, Benthoscolex seisuiae sp. n., is described from the Sea of Kumano, Japan, from depths of 487-596 m. The species is distinguishable from its congeners by the following features: i) palps 1.8 times as long as lateral antennae; ii) branchiae do not reach to the tip of the notochaetae. This is the first record of Benthoscolex from Japan. A partial mitochondrial cytochrome c oxidase subunit I gene sequence from the holotype of B. seisuiae sp. n. is provided for reliable species identification in the future.

  20. Heme Iron Coordination Structure of Heme Transport Protein HutB from Vibrio Cholerae

    Uchida, Takeshi; Funamizu, Takumi; Ogura, Mariko; Ishimori, Koichiro
    HutB is a putative heme transport protein located in the periplasmic space in Vibrio cholerae. Here, we purified HutB and characterized its heme binding properties. An analysis of the Soret band showed that there are two types of heme binding geometries depending on the heme concentration: 404-nm species are dominant at lower concentrations of heme, and 394-nm species dominate at higher concentrations. Moreover, a mutational study revealed that either Tyr65 or Tyr198 binds heme with the help of histidine, a property shared with another V. cholerae heme transport protein, HutX, despite the absence of sequence similarity, indicating that HutB acts...

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