Seibutsu Butsuri
Online ISSN : 1347-4219
Print ISSN : 0582-4052
ISSN-L : 0582-4052
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Volume 54, Issue 4
Issue 314
Displaying 1-18 of 18 articles from this issue
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Perspective
Overview
  • The Chaperonin GroEL Switches the Reaction Cycles in Response to the Concentration of Denatured Proteins
    Ryo IIZUKA, Taro UENO, Takashi FUNATSU
    2014Volume 54Issue 4 Pages 189-194
    Published: 2014
    Released on J-STAGE: July 30, 2014
    DOIhttps://doi.org/10.2142/biophys.54.189
    JOURNAL FREE ACCESS
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    The chaperonin GroEL is an essential molecular chaperone that mediates protein folding together with its cofactor GroES in Escherichia coli. It is widely accepted that a bullet-shaped 1 : 1 GroEL-GroES complex is formed throughout the cycle, whereas a football-shaped 1 : 2 GroEL-GroES complex is not formed. However, the accepted notion has been challenged by the recent findings that indicate the existence of the football-shaped complex. Here, we present the concept that GroEL can use both the bullet cycle and the football cycle and the choice of cycle is dependent on the concentration of denatured proteins.
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  • Dynamical Features of Neurons and Neural Networks: Chaos, Synchronization, Rhythm, and Propagation
    Hatsuo HAYASHI
    2014Volume 54Issue 4 Pages 195-200
    Published: 2014
    Released on J-STAGE: July 30, 2014
    DOIhttps://doi.org/10.2142/biophys.54.195
    JOURNAL FREE ACCESS
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    Neurons respond not only regularly but also irregularly to periodic stimulation depending on the stimulus strength and frequency. In the brain, field potential oscillations (rhythms) also respond not only regularly but also irregularly. These irregular responses are not stochastic, but deterministic chaos being subject to a simple nonlinear dynamical rule. This implies that neuron and neural network models described by deterministic dynamical equations reproduce even complex activities. In this review, I focus on dynamical features of neurons and neural networks such as chaos, synchronization, rhythm, and propagation. I will also mention the theta traveling wave in one direction, which would be crucial for sequence learning in the hippocampus.
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  • In vitro Reactivation of the Contractile Ring in the Fission Yeast Cell-ghost
    Jun KASHIWAZAKI, Issei MABUCHI
    2014Volume 54Issue 4 Pages 201-205
    Published: 2014
    Released on J-STAGE: July 30, 2014
    DOIhttps://doi.org/10.2142/biophys.54.201
    JOURNAL FREE ACCESS
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    Cytokinesis in many eukaryotes involves the closure of an actomyosin-based contractile ring (CR). We have established an in vitro system to study CR contraction. We show that CRs of permeabilized fission yeast cells undergo rapid contraction in an ATP and myosin-II-dependent manner in the absence of other cytoplasmic constituents. Neither actin polymerization nor its disassembly was required for closure of CRs although addition of exogenous actin cross-linking proteins blocked ring contraction. Using CRs generated from fission yeast cytokinesis mutants, we show that not all proteins required for assembly of the CR are required for its contraction in vitro.
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Review
  • Semi-intact Cell System and Cell Resealing Technique for Image-based Analysis of Intracellular Events: A Powerful Cellular Tool for Single Cell Biology
    Masayuki MURATA, Yoshiyuki NOGUCHI, Yuta HORIUCHI, Sakuya HORII, Fumi ...
    2014Volume 54Issue 4 Pages 206-209
    Published: 2014
    Released on J-STAGE: July 30, 2014
    DOIhttps://doi.org/10.2142/biophys.54.206
    JOURNAL FREE ACCESS
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    Semi-intact cells are cells whose plasma membrane is permeabilized with toxins by creating pores. Semi-intact cells allow for the exchange of the original cytosolic proteins with an exogenously-made cytosol prepared from cells of varying states, such as cells at different stages of the cell cycle, differentiation, or cells in a diseased state. Recently we found that the pores in semi-intact cells can be resealed by calcium ions. Here, we introduce a basic protocol for preparing a “disease-model cell” using the resealing technique of semi-intact cells, in which the cytosolic conditions of a diabetic liver was replicated, and demonstrate the disturbances in endocytosis and signal transduction in the diabetic liver-model cells.
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  • Developmental Process and Synchronized Bursts in Cultured Neuronal Networks
    Daisuke ITO, Kazutoshi GOHARA
    2014Volume 54Issue 4 Pages 210-214
    Published: 2014
    Released on J-STAGE: July 30, 2014
    DOIhttps://doi.org/10.2142/biophys.54.210
    JOURNAL FREE ACCESS
    Supplementary material
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    Cultured neuronal networks are very useful for studying fundamental mechanisms associated with nervous system development and functioning. We have investigated network development and synchronized burst activity of neuronal cells cultured on multi-electrode arrays (MEAs). Using immunofluorescence staining, we measured excitatory and inhibitory synapse densities during 1-month development of cultured rat cortical networks. We also cultured the neurons on MEAs at different densities to investigate minimum network size required for synchronized bursts. In addition, we performed neuronal cell patterning on MEAs to control the network construction. In this review, our recent findings published in some papers are presented.
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Topics
Topics (Young Scientist Series)
Theoretical and experimental techniques
Salon
Activity of Regional Branch
Young Voice
Letters from Abroad
Technical term
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