Author: J. W. S. Pringle
Publisher:
ISBN:
Category :
Languages : en
Pages : 57
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The flight muscles of gian water bugs provide the best material for a study of the peculiar properties of insect fibrillar muscle. Although little was previously known about the biology of these insect, three species, Lethocerus maximus, L. annulipes and B. Malkini have now been extensively studied in the field in Trinidad and the techniques for breeding L. maximus and B. malkini worked out. Against the background of studies carried out in Oxford in the last four years (Pringle, 1967) special attention was given to the biochemistry of the ATPase activity of actomyosin and myofibrils prepared from fibrillar flight muscles (Maruyama and Allen, 1967; Maruyama, Pringle and Tregear, in press). This enzyme is similar to that from vertebrate muscle in its sensitivity to ionic strength and its requirements for MgATP as substrate but its dependence on the concentration of Ca(2+) is different and this is related to the stretch activation shown by intact glycerinated muscle preparations (Ruegg and Tregear, 1966). Previous studies (Chaplain, 1966) suggested an important role for ADP in the control of ATPase activity of insect actomyosin. Further studies show that the ionic strength of the medium has an important effect on the inhibition or activation produced by ADP (Maruyama and Pringle, 1967). (Author).
Author: Roger H. Abbott
Publisher:
ISBN:
Category : Insects
Languages : en
Pages :
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Author: J. W. S. Pringle
Publisher:
ISBN:
Category :
Languages : en
Pages : 19
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Studies on glycerine-extracted fibres have shown that the oscillatory contractile properties of insect fibrillar flight muscle derive from certain peculiarities of the myofibrils, particularly an increase in ATPase activity when the fibres are extended and a stimulating effect of low concentrations of ADP. The molecular architecture differs in certain respects from that of vertebrate striated muscle. Giant water bugs, which provide the best source of fibrillar flight muscle, can be maintained in good condition in the laboratory. Certain species have been bred successfully but full maturation of the flight muscles has not yet been achieved. (Author).
Author: J. W. S. Pringle
Publisher:
ISBN:
Category :
Languages : en
Pages : 19
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Author: R. A. Chaplain
Publisher:
ISBN:
Category : Insects
Languages : en
Pages : 183
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Author: David Aitchison Smith
Publisher: Springer
ISBN: 9783030035259
Category : Medical
Languages : en
Pages : 0
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Book Description
Understanding the molecular mechanism of muscle contraction started with the discovery that striated muscle is composed of interdigitating filaments which slide against each other. Sliding filaments and the working-stroke mechanism provide the framework for individual myosin motors to act in parallel, generating tension and loaded shortening with an efficient use of chemical energy. Our knowledge of this exquisitely structured molecular machine has exploded in the last four decades, thanks to a bewildering array of techniques for studying intact muscle, muscle fibres, myofibrils and single myosin molecules. After reviewing the mechanical and biochemical background, this monograph shows how old and new experimental discoveries can be modelled, interpreted and incorporated into a coherent mathematical theory of contractility at the molecular level. The theory is applied to steady-state and transient phenomena in muscle fibres, wing-beat oscillations in insect flight muscle, motility assays and single-molecule experiments with optical trapping. Such a synthesis addresses major issues, most notably whether a single myosin motor is driven by a working stroke or a ratchet mechanism, how the working stroke is coupled to phosphate release, and whether one cycle of attachment is driven by the hydrolysis of one molecule of ATP. Ways in which the theory can be extended are explored in appendices. A separate theory is required for the cooperative regulation of muscle by calcium via tropomyosin and troponin on actin filaments. The book reviews the evolution of models for actin-based regulation, culminating in a model motivated by cryo-EM studies where tropomyosin protomers are linked to form a continuous flexible chain. It also explores muscle behaviour as a function of calcium level, including emergent phenomena such as spontaneous oscillatory contractions and direct myosin regulation by its regulatory light chains. Contraction models can be extended to all levels of calcium-activation by embedding them in a cooperative theory of thin-filament regulation, and a method for achieving this grand synthesis is proposed. Dr. David Aitchison Smith is a theoretical physicist with thirty years of research experience in modelling muscle contractility, in collaboration with experimental groups in different laboratories.
Author: Jim Vigoreaux
Publisher: Springer Science & Business Media
ISBN: 0387312137
Category : Science
Languages : en
Pages : 308
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Methods for Obtaining X-Ray Diffraction Patterns from Drosophila 198 Diffraction Patterns from Drosophila IFM 203 Concluding Remarks 211 Note Added in Proof 211 17. Functional and Ecological Effects of Isoform Variation in Insect Flight Muscle 214 James H. Marden Abstract 214 Introduction 215 Nature's Versatile Engine 215 The Underlying Genetics: An Underinflated Genome and a Hyperinflated Transcriptome and Proteome 216 Functional Effects of Isoform Variation 219 Alternative Splicing and the Generation of Combinatorial Complexity 220 Functional Consequences of Naturally Occurring Isoform Variation 220 18. Muscle Systems Design and Integration 230 Fritz- OlafLehmann Abstract 230 Power Requirements for Flight 230 Power Reduction 233 Power Constraints on Steering Capacity 234 Balancing Power and Control 236 Changes in Muscle Efficiency in Vivo 238 Concluding Remarks 239 From the Inside Out 19. Molecular Assays for Acto-Myosin Interactions 242 John C. Sparrow and Michael A. Geeves Abstract 242 Introduction 242 Myosin Purification and Preparation of the SI Fragment 243 Purification of Flight Muscle Actin 244 Assays of Myosin and Acto-Myosin 244 Major Conclusions Relating to the Enzymatic Properties of Insect Flight Muscle Acto-Myosin 247 Major Questions about Insect Flight Muscle Acto-Myosin Kinetics That Remain 249 20.
Author: John Squire
Publisher: Springer Science & Business Media
ISBN: 1461331838
Category : Science
Languages : en
Pages : 704
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Book Description
Muscular contraction provides one of the most fascinating topics for a biophysicist to study. Although muscle comprises a molecular machine whereby chemical energy is converted to mechanical work, its action in producing force is something that is readily observable in everyday life, a feature that does not apply to most other structures of biophysical inter est. In addition, muscle is so beautifully organized at the microscopic level that those important structural probes, electron microscopy (with the associated image analysis methods) and X-ray diffraction, have pro vided a wealth of information about the arrangements of the constituent proteins in a variety of muscle types. But, despite all this, the answer to the question "How does muscle work?" is still uncertain, especially with regard to the molecular events by which force is actually generated, and the question remains one of the major unsolved problems in biology. With this problem in mind, this book has been written to collect together the available evidence on the structures of the muscle fila ments and on their arrangements in different muscle cells, to extract the common structural features of these cells, and thus to attempt to define a possible series of mechanical steps that will describe at molecular resolu tion the process by which force is generated. The book cannot be considered to be an introductory text; in fact, it presents a very detailed account of muscle structure as gleaned mainly from electron microscopy and X-ray diffraction.
Author: Gerald Pollack
Publisher: Springer Science & Business Media
ISBN: 1468447033
Category : Medical
Languages : en
Pages : 883
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Book Description
Prior to the emergence of the sliding filament model, contraction theories had been in abundance. In the absence of the kinds of structural and biochemical information available today, it has been a simple matter to speculate about the possible ways in which tension generation and shortening might occur. The advent of the sliding filament model had an immediate impact on these theories; within several years they fell by the wayside, and attention was redirected towards mechanisms by which the filaments might be driven to slide by one another. In terms of identifying the driving mechanism, the pivotal observa tion was the electron micrographic indentification of cross-bridges extending from the thick filaments. It was quite naturally assumed that such bridges, which had the ability to split ATP, were the molecular motors, i.e., that they were the sites of mechanochemical transduction. Out of this presumption grew the cross-bridge model. in which filament sliding is presumed to be driven by the cyclic interaction of cross-bridges with complementary actin sites located along the thin filaments.
Author: J. W. S. Pringle
Publisher: Cambridge University Press
ISBN: 052105995X
Category : Insects
Languages : en
Pages : 146
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