RUI: COLLABORATIVE RESEARCH. Non-uniform distribution of muscle fiber strain in squid mantle muscle: implications for musculoskeletal system structure, function, and evolution.

RUI: COLLABORATIVE RESEARCH. Non-uniform distribution of muscle fiber strain in squid mantle muscle: implications for musculoskeletal system structure, function, and evolution.

Joseph T. Thompson (Franklin & Marshall College) and William M. Kier (University of North Carolina), Co-PIs.

Proposal # IOS-0950827

Abstract

The hollow, cylindrical shape of the bodies and muscular organs of soft-bodied invertebrate animals is well suited to functions in skeletal support, movement and locomotion. This ubiquitous shape, however, may incur a previously unrecognized cost - large non-uniformities in shortening among the muscle cells arranged circumferentially around the body. Such non-uniformities pose serious problems for the muscles, connective tissues, and neural control systems of the muscular organ, and may force muscle cells in some regions of the body wall to operate with reduced mechanical efficiency during locomotion and movement. We have identified a hollow cylindrical muscular organ, the mantle of squids, in which circumferential muscle cells at different locations likely produce different amounts of force, shorten at different velocities, and generate different amounts of mechanical work during a single contraction of the tubular body. We will use morphological, electromyographic, and biomechanical approaches to investigate these potential problems and identify mechanisms in the skeletal support system of the mantle that may mitigate them. The results of our work promise to reveal new general principles of function for skeletal support systems, not just for soft-bodied invertebrates but for all animals with cylindrical muscular organs. Our research will provide opportunities for undergraduate and graduate students from diverse ethnic backgrounds to learn experimental techniques in kinematics, muscle physiology, and microscopy. Furthermore, our student participants will gain experience in the collaborative and integrative nature of science as they work in teams with peers from different institutions to collect and analyze data, and present the results of their work at national and local scientific conferences.