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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 4.627

  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. On the Andrianov type identity for power series attached to Jacobi forms and its application

    Katsurada,Hidenori; Kawamura,Hisa-aki

  10. The Euler characteristic of a generic wave front in a 3-manifold

    Izumiya,S.; Marar,W.L.
    We give a relation between Euler characteristics of a generic closed Legendrian surface and its wavefront.

  11. Periodic solutions of elliptic-parabolic variational inequalities with time-dependent constraints

    Kubo,Masahiro; Yamazaki,Noriaki
    We study periodic solutions of quasilinear elliptic-parabolic variational inequalities with time-dependent constraints. Assuming that the constraint changes periodically in time, we prove existence of periodic solutions. Moreover, applications of the general results are given.

  12. Dynamical Yang-Baxter Maps

    In this work, we propose and investigate dynamical Yang-Baxter maps, some of which produce solutions to the (quantum) dynamical Yang-Baxter equation. Suppose that L is a loop and a group. If their unit elements coincide, then L gives birth to a bijective dynamical Yang-Baxter map from L x L to L x L whose dynamical parameter belongs to L. The above group L is abelian if and only if the corresponding dynamical Yang-Baxter map satisfies the unitary condition.

  13. Quasilinear parabolic variational inequalities with time-dependent constraints

    Kubo,Masahiro; Yamazaki,Noriaki
    We study variational inequalities with time-dependent constraints for quasilinear parabolic PDE of divergence form. Introducing a general condition on the constrains, we prove existence, uniqueness and order property of solution. Some applications are given.

  14. Elliptic-parabolic variational inequalities with time-dependent constraints

    Kubo,Masahiro; Yamazaki,Noriaki
    We study variational inequalities for elliptic-parabolic eqnations with time-dependent constraints. Introducing a general condition for the time-dependence of convex sets defining the constraints, we establish theorems concerning existence, uniqueness as well as order property of solution. Some applications of the general results are given.

  15. Periodic total variation flow of non-divergence type in R^n

    Giga,Mi-Ho; Giga,Yoshikazu; Pozar,Norbert
    We introduce a new notion of viscosity solutions for a class of very singular nonlinear parabolic problems of non-divergence form in a periodic domain of arbitrary dimension, whose di usion on flat parts with zero slope is so strong that it becomes a nonlocal quantity. The problems include the classical total variation flow and a motion of a surface by a crystalline mean curvature. We establish a comparison principle, the stability under approximation by regularized parabolic problems, and an existence theorem for general continuous initial data.

  16. Explicit formulas for the twisted Koecher-Maaβ series of the Duke-Imamoglu-Ikeda lift and their applications

    We give an explicit formula for the twisted Koecher-Maa? series of the Duke-Imamoglu-Ikeda lift. As an application we prove a certain algebraicity result for the values of twisted Rankin-Selberg series at integers of half-integral weight modular forms.

  17. Resonant interaction of Rossby waves in two-dimensional flow on a β plane

    Yamada,Michio; Yoneda,Tsuyoshi
    An incompressible two-dimensional flow on a β plane is considered. The β plane is a tangent plane of a sphere to approximately describe fluid motion on a rotating sphere assuming that the Coriolis parameter is a linear function of the latitude. Rossby waves are expected to dominate the β plane dynamics, and here in this paper, a mathematical support for the crucial role of the resonant pairs of the Rossby waves is given.



  19. What does the partial autocorrelation function look like for large lags

    We prove a representation of the partial autocorrelation function α(・) of a stationary process { Xn : n ∈ Z}, in terms of the AR(∞) and MA(∞) coefficients. We apply it to show what α(n) looks like for large n, especially, when {Xn} is a long-memory process. For example, if {Xn} is a fractional ARIMA(p. d. q) process, then we have a(n)~d/n as n → ∞.

  20. Residues of holomorphic vector fields on singular varieties

    Lehmann,D; Suwa,T

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