Chapter category: Development
Projectin the Elastic Protein of the C-filaments
Nature's Versatile Engine: Insect Flight Muscle Inside and Out
Edited by: Jim O. VigoreauxISBN: 0-387-25798-5
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Chapter authors:
Agnes Ayme-Southgate and Richard Southgate
In adult insects, the highly specialized indirect flight muscles (abbreviated as IFMs) are powerful muscles adapted for the rapid repeated contractions necessary for flight. These muscles are referred to as asynchronous muscles, because they undergo multiple rounds of contraction for each single nerve impulse, a property made possible by the stretch-activation mechanism.1-5 The stretch-activation mechanism is explained as a “delayed increase in tension due to stretch” that activates the muscle and results in contraction. The IFMs are attached to the cuticle (exoskeleton) and because they are organized as two sets of nearly perpendicular muscles, their length oscillate in response to the stretch activation-contraction cycles. The stretch activation mechanism has been shown to be an intrinsic property of the myofibrillar apparatus, 1 and is made possible by several special physiological adaptations, such as a high resting stiffness. To explain some of the IFMs’ properties, early models proposed the existence of an additional third filament system with elastic properties, which is usually referred to as the connecting or C-filament system. Electron microscopy studies of insect flight muscles revealed the presence of fine connections between the Z bands and the thick filaments.6-11 In particular, electron microscopy of stretched myofibrils or purified Z disks of insect flight muscles have shown the presence of filaments extending or “projecting” from the Z band towards the myosin filaments and just overlapping the tip of the A band.12,13 In honeybee IFMs, connecting filaments can be extended to well over ten times their normal rest length. When these muscles are stretched in rigor and then released, the recoil forces of the connecting filaments cause the sarcomere to shorten, leading to the crumpling of the thin filaments held in rigor.9 The search for component(s) of the C-filament system led to the identification and characterization of the protein, projectin. Saide unequivocally demonstrated by antibody staining and biochemical analysis that the third connecting filament of honeybee flight muscles is composed of projectin.12
Additional chapters from this book:
Insect Flight Muscle Chemomechanics
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The biochemical and mechanical basis of insect flight has captivated the interest of biologists for decades. This chapter presents a brief review of the approaches used and results obtained by inves...
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Troponin, Tropomyosin and GST are generic names of protein families that play a variety of cellular roles in the biology of uni- and multicellular organisms. In muscles, specific family members are ...
A Naturalist’s View of Insect Flight Muscle
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By almost any measure, insects as a group are an astounding evolutionary achievement. Through their diversity and their adaptation to a great range of life-styles, forms, and physical and biological...
Structure of The Insect Thick Filaments
Gernot Beinbrech and Gereon Ader
Myosin filaments of insect indirect flight muscles (IFM) are 17 to 19 nm thick and 1.9 to 3.6 µm long structures with probably 4 cross-bridges per level (=crown). These crowns repeat in periods of 1...
Insect Flight Muscle Chemomechanics
David Maughan and Douglas Swank
The biochemical and mechanical basis of insect flight has captivated the interest of biologists for decades. This chapter presents a brief review of the approaches used and results obtained by inves...
3D Structure of Myosin Crossbridges in Insect Flight Muscle: Toward Visualization of the Conformations During Myosin Motor Action
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Insect flight muscle (IFM) provides a model system that allows direct viewing of individual myosin head structures in situ that give rise to the average structures reported by X-ray patterns and by ...
The Contributions of Genetics to the Study of Insect Flight Muscle Function
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The utility of Drosophila as a model genetic organism has had a profound impact upon our understanding of muscle assembly and function. This has arisen from the large number of mutant alleles that h...
Actin and Arthrin
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Filamentous actin forms the core of all muscle thin filaments and is an integral part of the acto-myosin motor system that powers muscle contraction. Muscle actin isoforms show considerable sequence...
X-Ray Diffraction of Indirect Flight Muscle from Drosophila in Vivo
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The indirect flight muscle (IFM) of the fruit fly, Drosophila, represents a powerful model system for integrated structure and function studies because of the ease of genetically manipulating this o...
Molecular Assays for Acto-myosin Interactions
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The indirect flight muscles of insects are highly specialised to produce power for flight. Asynchronous flight muscle contraction is largely isometric (3-4% shortening in vivo) and can occur at high...
Stretch Activation: Toward a Molecular Mechanism
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Insect flight is often powered by high wing beat frequencies. Surprisingly, the flight muscles of some insects are capable of driving high wing beats without extensive calcium cycling machinery. Rat...
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The myofibril is a multiprotein complex that performs the contractile activity of the muscle cell. Biochemical experiments over the past decades have revealed protein interactions that are critical ...
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Vivek Vishnudas and Jim O. Vigoreaux
The high power output necessary for insect flight has resulted in the evolution of muscles with large and abundant myofibrils, the so called ‘myofibrillar’ muscles. In principle, this modification s...
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The Insect Z-band
Judith D. Saide
The Z-band is an electron dense structure that borders sarcomeres in striated muscle. It is a complex assembly of proteins that organizes and stabilizes both thick and thin filament arrays in the co...
Myosin
Becky M. Miller and Sanford I. Bernstein
The molecular motor myosin, composed of two heavy chains and four light chains, is responsible for defining both structural and mechanical properties of insect flight muscle. Myosin polymerizes into...
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In Drosophila, paramyosin and miniparamyosin are structural components of thick filaments that have a similar structure to the myosin heavy chain rod tail. Both proteins are rod-like molecules with ...
Comparative Physiology of Insect Flight Muscle
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Insect flight is powered by muscles that attach more-or-less directly to the wings (direct flight muscles) and muscles that bring about wing movement by distorting the insect’s thorax (indirect flig...
Functional and Ecological Effects of Isoform Variation in Insect Flight Muscle
James H. Marden
Nearly all of the known structural molecules in insect flight muscles exist as multiple isoforms. Both post-transcriptional and post-translational mechanisms are responsible for this variability. Am...
Some Functions of Proteins from the Drosophila Sallimus (sls) Gene
Belinda Bullard, Mark C. Leake and Kevin Leonard
Insect flight muscles contract at high frequencies and are activated by periodically stretching the muscles. For the stretch to have an effect, the muscles must be stiff. Two elastic proteins, proje...
Muscle Systems Design and Integration
Fritz-Olaf Lehmann
The recent advances in experimental technology allows us to assess the mechanical power output and function of the Drosophila flight muscle within the context of the flying animal. In an intact anim...
Projectin the Elastic Protein of the C-filaments
Agnes Ayme-Southgate and Richard Southgate
In adult insects, the highly specialized indirect flight muscles (abbreviated as IFMs) are powerful muscles adapted for the rapid repeated contractions necessary for flight. These muscles are referr...
