Network of Palladium-Based Nanorings Synthesized by Liquid-Phase Reduction Using DMSO-H2O: In Situ Monitoring of Structure Formation and Drying Deformation by ASEM

Komenami, Takuki; Yoshimura, Akihiro; Matsuno, Yasunari; Sato, Mari; Sato, Chikara

doi:10.3390/ijms21093271

Cited by 4 publications

(4 citation statements)

References 30 publications

(34 reference statements)

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“…For the further analyses of the precise movement of the ATPase molecules, we are planning to perform statistical image analysis based on machine learning in combination with cryo-electron microscopy (cryo-EM) [ 49 ] and liquid-phase immuno-EM including the use of the atmospheric scanning electron microscope (ASEM) we have developed [ 50 , 51 , 52 , 53 , 54 ].…”

Section: Discussionmentioning

confidence: 99%

Ca2+-ATPase Molecules as a Calcium-Sensitive Membrane-Endoskeleton of Sarcoplasmic Reticulum

Nakamura

Maruyama

Tajima

et al. 2021

IJMS

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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.

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Section: Discussionmentioning

confidence: 99%

Ca2+-ATPase Molecules as a Calcium-Sensitive Membrane-Endoskeleton of Sarcoplasmic Reticulum

Nakamura

Maruyama

Tajima

et al. 2021

IJMS

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“…Since cracks are created when a solid 3D structure is crushed by a large pressure, these results prompt the hypothesis that stable ATPase crystal patches gather close to one another to form a tight assembly, transforming the vesicle into a 3D spherical form. However, when the liquid droplet containing the SR vesicles was dried on the carbon film of a TEM grid, the huge water surface tension pressed and crushed the spherical 3D structure of the SR, as suggested by the crushing of filamentous palladium networks [ 14 ] dynamically monitored using our developed Atmospheric SEM (ASEM) [ 15 , 16 , 17 , 18 ] as the water droplet containing them dried.…”

Section: Discussionmentioning

confidence: 99%

Ca2+ Dependent Formation/Collapse of Cylindrical Ca2+-ATPase Crystals in Scallop Sarcoplasmic Reticulum (SR) Vesicles: A Possible Dynamic Role of SR in Regulation of Muscle Contraction

Nakamura

Maruyama

Tajima

et al. 2023

IJMS

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[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.

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“…For example, the group of Sato successfully used an inverted atmospheric SEM with an open sample holder isolated with a SiN x film to observe deposits of Au and silver on Au electrodes 22) and the palladium-based nanostructures in liquid. 23) The group of Mølhave reported that, using a standard SEM, electroless deposition of nickel and electrodeposition of copper on platinum electrodes were observed through a specially microfabricated electron window of a thin (50 nm) Si-rich silicon nitride (SiN x ) film. 24,25) Orsini et al studied the interfaces of plastic lithium battery/cell via in-situ SEM and concluded that the morphology of deposits was correlated to current density.…”

Section: Introductionmentioning

confidence: 99%

In-situ high-resolution scanning electron microscopy observation of electrodeposition and stripping of lead in an electrochemical cell

Oshima

Tomitori

2021

Jpn. J. Appl. Phys.

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A compact electrochemical cell capped with a silicon nitride (SiN) film of 50 nm thick as an electron window was developed for a side-entry holder of a high-resolution scanning electron microscope (SEM). Electrodeposition and stripping of lead (Pb) were examined on a gold electrode formed on the SiN film, which was faced inside the cell filled with an aqueous solution of lead nitrite. The SEM images of growth and dissociation of Pb were recorded simultaneously with cyclic voltammograms, controlled with a two-terminal potentiostat. Particulate growth of Pb at the edge of a gold (Au) electrode was observed at the underpotential deposition of Pb, followed by dendrite growth of Pb at higher deposition potentials. The growth mode changed depending on the edge morphology of the Au electrode. This indicated that in-situ microscopic observation was invaluable for understanding the phenomena of electrodeposition in electrochemistry.

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Network of Palladium-Based Nanorings Synthesized by Liquid-Phase Reduction Using DMSO-H2O: In Situ Monitoring of Structure Formation and Drying Deformation by ASEM

Cited by 4 publications

References 30 publications

Ca2+-ATPase Molecules as a Calcium-Sensitive Membrane-Endoskeleton of Sarcoplasmic Reticulum

Ca2+-ATPase Molecules as a Calcium-Sensitive Membrane-Endoskeleton of Sarcoplasmic Reticulum

Ca2+ Dependent Formation/Collapse of Cylindrical Ca2+-ATPase Crystals in Scallop Sarcoplasmic Reticulum (SR) Vesicles: A Possible Dynamic Role of SR in Regulation of Muscle Contraction

In-situ high-resolution scanning electron microscopy observation of electrodeposition and stripping of lead in an electrochemical cell

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