Search

Your search keyword '"Maruyama, Yuusuke"' showing total 47 results
Start Over Author "Maruyama, Yuusuke"
47 results on '"Maruyama, Yuusuke"'

10. Ca 2+ Dependent Formation/Collapse of Cylindrical Ca 2+ -ATPase Crystals in Scallop Sarcoplasmic Reticulum (SR) Vesicles: A Possible Dynamic Role of SR in Regulation of Muscle Contraction.

Author

Nakamura, Jun, Maruyama, Yuusuke, Tajima, Genichi, Hayakawa, Satoshi, Suwa, Makiko, and Sato, Chikara

Subjects
*CALCIUM ions, *SARCOPLASMIC reticulum, *RYANODINE receptors, *SCALLOPS, *MUSCLE contraction, *CRYSTALS
Abstract

[Ca2+]-dependent crystallization of the Ca2+-ATPase molecules in sarcoplasmic reticulum (SR) vesicles isolated from scallop striated muscle elongated the vesicles in the absence of ATP, and ATP stabilized the crystals. Here, to determine the [Ca2+]-dependence of vesicle elongation in the presence of ATP, SR vesicles in various [Ca2+] environments were imaged using negative stain electron microscopy. The images obtained revealed the following phenomena. (i) Crystal-containing elongated vesicles appeared at ≤1.4 µM Ca2+ and almost disappeared at ≥18 µM Ca2+, where ATPase activity reaches its maximum. (ii) At ≥18 µM Ca2+, almost all SR vesicles were in the round form and covered by tightly clustered ATPase crystal patches. (iii) Round vesicles dried on electron microscopy grids occasionally had cracks, probably because surface tension crushed the solid three-dimensional spheres. (iv) [Ca2+]-dependent ATPase crystallization was rapid (<1 min) and reversible. These data prompt the hypothesis that SR vesicles autonomously elongate or contract with the help of a calcium-sensitive ATPase network/endoskeleton and that ATPase crystallization may modulate physical properties of the SR architecture, including the ryanodine receptors that control muscle contraction. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

18. Elongation and Contraction of Scallop Sarcoplasmic Reticulum (SR): ATP Stabilizes Ca 2+ -ATPase Crystalline Array Elongation of SR Vesicles.

Author

Nakamura, Jun, Maruyama, Yuusuke, Tajima, Genichi, Suwa, Makiko, and Sato, Chikara

Subjects
*SARCOPLASMIC reticulum, *SCALLOPS, *ADENOSINE triphosphatase, *ELECTRON microscopy, *MONOMERS
Abstract

The Ca2+-ATPase is an integral transmembrane Ca2+ pump of the sarcoplasmic reticulum (SR). Crystallization of the cytoplasmic surface ATPase molecules of isolated scallop SR vesicles was studied at various calcium concentrations by negative stain electron microscopy. In the absence of ATP, round SR vesicles displaying an assembly of small crystalline patches of ATPase molecules were observed at 18 µM [Ca2+]. These partly transformed into tightly elongated vesicles containing ATPase crystalline arrays at low [Ca2+] (≤1.3 µM). The arrays were classified as ''tetramer", "two-rail" (like a railroad) and ''monomer". Their crystallinity was low, and they were unstable. In the presence of ATP (5 mM) at a low [Ca2+] of ~0.002 µM, "two-rail" arrays of high crystallinity appeared more frequently in the tightly elongated vesicles and the distinct tetramer arrays disappeared. During prolonged (~2.5 h) incubation, ATP was consumed and tetramer arrays reappeared. A specific ATPase inhibitor, thapsigargin, prevented both crystal formation and vesicle elongation in the presence of ATP. Together with the second part of this study, these data suggest that the ATPase forms tetramer units and longer tetramer crystalline arrays to elongate SR vesicles, and that the arrays transform into more stable "two-rail" forms in the presence of ATP at low [Ca2+]. [ABSTRACT FROM AUTHOR]

Published
2022
Full Text
View/download PDF

19. Inflow Generation for LES Calculation of Turbulent Boundary Layer

Author

MARUYAMA, Takashi, MARUYAMA, Yuusuke, Rodi, W., and HIRAOKA, Hisashi

Subjects
conditional random fields, LES, 乱流境界層, turbulent boundary layer, 流入変動気流, 451.32, generated inflow, 451.3, 条件付確率場
Abstract

現在, 建築物周りの非定常乱流場の解析手法としてはラージエディシミュレーション(LES)が有望視されているが, その実用化に際しては流入境界条件の与え方が大きな障害の一つとなっている。本報では条件付確率場の理論を用いた乱流場の生成手法により, 上流側の乱流場を直接計算することなく希望する統計量をもった乱流場を発生させる方法を示す。発生された乱流場は実験結果と比較され, その有効性が確かめられた。, The interpolating method of the flow fluctuation conditioned by the experimental data was introduced. The flow signals at the inlet boundary in the turbulent boundary layer just behind the roughness elements were generated. The flows were interpolated in Fourier space as stochastic processes in a conditional random fields so as to realize the equivalent statistical quantities of experimental results. The digitally generated signals satisfied the statistics up to the second order moments fairly well.The turbulent field just behind the roughness calculated by LES using these inflow conditions was compared with the experimental data and examined.The calculated result shows rather good agreement in mean wind field but the attenuation of wind fluctuation in high frequency caused by the scale of mesh grids was observed.

Published
1997

25. 3E1022 Direct electron microscopy of protein crystals and Mvconlasma cells in solution using the Atmosnheric SEM(Proteins:Structure,Oral Presentation,The 50th Annual Meeting of the Biophysical Society of Japan)

Author

Maruyama, Yuusuke, primary, Ebihara, Tatsuhiko, additional, Nakane, Daisuke, additional, Nishiyama, Hidetoshi, additional, Nishizaka, Takayuki, additional, Senda, Miki, additional, Mio, Kazuhiro, additional, Suga, Mitsuo, additional, Senda, Toshiya, additional, Miyata, Makoto, additional, and Sato, Chikara, additional

Published
2012
Full Text
View/download PDF

34. MS36

Author

IWASAKI, Kenji, primary, MIO, Kazuhiro, additional, OGURA, Toshihiko, additional, MARUYAMA, Yuusuke, additional, MIO, Muneyo, additional, ABE, Sachie, additional, YANAGIHARA, Masako, additional, SATO, Chikara, additional, and OMURA, Toshihiro, additional

Published
2009
Full Text
View/download PDF

36. KAGAKU TO SEIBUTSU

Author

MIO, Kazuhiro, primary, OGURA, Toshihiko, additional, MARUYAMA, Yuusuke, additional, MIO, Muneyo, additional, MANAKA, Sachie, additional, and SATO, Chikara, additional

Published
2009
Full Text
View/download PDF

39. This title is unavailable for guests, please login to see more information.

Author

MARUYAMA, Yuusuke, MARUYAMA, Takashi, 00190570, MARUYAMA, Yuusuke, MARUYAMA, Takashi, and 00190570

Abstract

This report presents the result of LES of flow around a 3D prism (1:1:0.5 rectangular-prism) in turbulent boundary layer at high Reynolds number. The inflow wind fluctuations conditioned by the experimental data were generated artificially.The turbulent flows with two different meshes were examined. The characteristics of turbulences and the pressure distribution on the surface of prism was effected by the inflow turbulence and the mesh configurations.

Published
1998

40. This title is unavailable for guests, please login to see more information.

Author

MARUYAMA, Takashi, MARUYAMA, Yuusuke, Rodi, W., HIRAOKA, Hisashi, 00190570, MARUYAMA, Takashi, MARUYAMA, Yuusuke, Rodi, W., HIRAOKA, Hisashi, and 00190570

Abstract

The interpolating method of the flow fluctuation conditioned by the experimental data was introduced. The flow signals at the inlet boundary in the turbulent boundary layer just behind the roughness elements were generated. The flows were interpolated in Fourier space as stochastic processes in a conditional random fields so as to realize the equivalent statistical quantities of experimental results. The digitally generated signals satisfied the statistics up to the second order moments fairly well.The turbulent field just behind the roughness calculated by LES using these inflow conditions was compared with the experimental data and examined.The calculated result shows rather good agreement in mean wind field but the attenuation of wind fluctuation in high frequency caused by the scale of mesh grids was observed.

Published
1997

42. Organized Session (Wind Energy)

Author

Matsumiya, Hikaru, primary, ISHIHARA, Takeshi, additional, Imamura, Hiroshi, additional, Yoshida, Shigeo, additional, MATSUZAKA, Tomoyuki, additional, KODAMA, Naruhito, additional, ARAKAWA, Chuichi, additional, ARIGA, Seiichi, additional, IIDA, Makoto, additional, MARUYAMA, Yuusuke, additional, SHIMURA, Masayuki, additional, YOSHIE, Ryuichiro, additional, WEI, Ran, additional, and SEI, Kazuichi, additional

Published
2001
Full Text
View/download PDF

46. Ca 2+ -ATPase Molecules as a Calcium-Sensitive Membrane-Endoskeleton of Sarcoplasmic Reticulum.

Author

Nakamura, Jun, Maruyama, Yuusuke, Tajima, Genichi, Komeiji, Yuto, Suwa, Makiko, Sato, Chikara, and Fedorova, Olga V.

Subjects
*SARCOPLASMIC reticulum, *MUSCLE contraction, *MEMBRANE proteins, *CALCIUM ions, *TRANSMISSION electron microscopy, *MOLECULES, *RYANODINE receptors, *RYANODINE
Abstract

The Ca2+-transport ATPase of sarcoplasmic reticulum (SR) is an integral, transmembrane protein. It sequesters cytoplasmic calcium ions released from SR during muscle contraction, and causes muscle relaxation. Based on negative staining and transmission electron microscopy of SR vesicles isolated from rabbit skeletal muscle, we propose that the ATPase molecules might also be a calcium-sensitive membrane-endoskeleton. Under conditions when the ATPase molecules scarcely transport Ca2+, i.e., in the presence of ATP and ≤ 0.9 nm Ca2+, some of the ATPase particles on the SR vesicle surface gathered to form tetramers. The tetramers crystallized into a cylindrical helical array in some vesicles and probably resulted in the elongated protrusion that extended from some round SRs. As the Ca2+ concentration increased to 0.2 µm, i.e., under conditions when the transporter molecules fully carry out their activities, the ATPase crystal arrays disappeared, but the SR protrusions remained. In the absence of ATP, almost all of the SR vesicles were round and no crystal arrays were evident, independent of the calcium concentration. This suggests that ATP induced crystallization at low Ca2+ concentrations. From the observed morphological changes, the role of the proposed ATPase membrane-endoskeleton is discussed in the context of calcium regulation during muscle contraction. [ABSTRACT FROM AUTHOR]

Published
2021
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results