10 Muscle

Abstract

I. INTRODUCTION
Studies of Caenorhabditis elegans muscle have sought to determine the role of specific components, both in the assembly of the myofilament lattice during development and in the contractile process itself. The proper assembly of the muscle structure is likely to involve principles that are generally important in the spatial differentiation of the organism, and muscle, with many of its major components known and with its well-defined structure, has advantages for discovering these principles. The propensity of the major components for self-assembly in vitro is well documented, but how the assembly is controlled and modulated in vivo to yield a well-defined lattice structure is unclear. The variety of forms that the major muscle filaments assume—from their less ordered cytoplasmic forms, to smooth muscle, to the almost crystalline arrangement in insect flight muscle—attests to the importance of this control. The fundamental mechanism of force generation in all these forms is known to involve the sliding of myosin-containing thick filaments past thin filaments. Despite the universal importance of the actomyosin mechanism, the details of force generation—how the chemical energy of ATP is transduced to the mechanical work of movement—are only poorly understood.

A combination of genetic, biochemical, and morphological approaches has been applied to the study of C. elegans muscle assembly and function. This combination of approaches has been very powerful in understanding analogous processes in prokaryotes and is proving successful in the worm. The general advantages that C. elegans has for studying mutations affecting movement apply...