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...

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 animal, production and control of aerodynamic forces during flight depend on several factors...

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, projectin and kettin, are responsible for a large part of the muscle stiffness. Thin filaments...

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. Among these mechanisms, alternative splicing is noteworthy for the ability to create a large...

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 flight muscles). Flight stability and steering are achieved by differential activation of power...

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 a high alpha-helical content in the long central domains, and exist as dimers. While...

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 thick filaments that are a major component of the sarcomeric units of myofibrils. In the...

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 contractile apparatus. By anchoring actin filaments and protein extensions of myosin filaments,...

In this chapter we describe the special properties of insect muscle thin filament proteins and the way in which they differ from those in vertebrates. As in the vertebrate, the repeating unit of the muscle fibre (sarcomere) contains interdigitated thick (myosin containing) and thin (actin...

Asynchronous insect flight muscle (IFM) relies on high frequency operation to achieve higher power output than a comparable synchronous muscle. The biochemical, ultra structural, and mechanical adaptations that define the performance of this muscle type are not completely understood. IFM is...

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 should come with a trade-off as the broader diameter of the myofibril would slow ATP/ADP flux...

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 for regulated contractile activity and for maintaining myofibril integrity and structural...

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. Rather than precisely timed signals from motor neurons driving each contraction, nervous...

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 oscillatory frequencies. Contraction kinetics are the property of the myofibrils and...

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 organism. Recent advances in synchrotron technology have allowed collection of high quality two...

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 conservation compared to all actins, but insect actins form a distinct group. Within insect...

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 have been isolated and characterized using a variety of screens, and also reflects an highly...

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 mechanical behavior of the fibers. Coordinating x-ray diffraction, physiological monitoring...

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 investigators intent on understanding the chemomechanical basis of contraction in insect muscle. We...

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 14.5 nm along the longitudinal axis of the filament. The cross-bridges are located at 4 helical...

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 environments, they offer unparalleled insights into the constraints, selective pressures and...

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 associated to the actin based thin filament where they contribute to the sarcomere...

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 investigators intent on understanding the chemomechanical basis of contraction in insect muscle. We...