Research

I ask three broad sets of questions in my research:

How do the structure, physiology, and mechanical properties of the muscles and connective tissues of the musculoskeletal system change during grow? In what ways do musculoskeletal structures, physiology and mechanics also vary across individuals and species?
What are the consequences and tradeoffs of these changes for movement and locomotion?
What factors have influenced changes in musculoskeletal form and function over ontogenetic (i.e., related to growth and development) and evolutionary time scales?

Students who work in my lab pursue questions that span multiple scales of organization, from molecules and cells to organism-environment interactions, and the questions of interest are often at the interfaces of biology, physics, and mathematics. Aside from students, the stars of the lab are soft-bodied marine invertebrates, especially cephalopod molluscs (squid, cuttlefish, and octopus) and, more recently, marine worms (especially the active and aggressive bloodworm Glycera dibranchiata).

Current Projects:

The diversity of obliquely striated muscle structure and function

Obliquely striated muscles occur in members of at least 17 phyla and may have evolved independently several times, yet the implications of oblique striation for muscle function are unknown. It has been assumed for decades that oblique striation permits relatively high force output over an extraordinary range of muscle lengths, a phenomenon known as superelongation. Recently, however, work by William Kier, Kari Taylor-Burt, Julia Olszewski-Jubelirer, and I suggests that obliquely striated muscles exhibit diversity in both the operating length range and the length-force relationship (LFR). We hypothesize that obliquely striated muscle evolved in soft bodied invertebrates not for superelongation but instead to allow adjustment of the LFR to accommodate the operating length range of a muscle fiber. We're currently attempting to investigate the the LFR coupled with in vivo measurements of muscle activation and operating length ranges in obliquely striated muscles from a diverse group of soft-bodied invertebrates.

Related recent publications:

Thompson, J.T., Taylor-Burt, K.R., and Kier, W.M. (2023). One size does not fit all: diversity of length-force properties of obliquely striated muscles. J. Exp. Biol. 226, jeb244949. doi:10.1242/jeb.244949.
Taylor-Burt, K.R., Kier, W.M., Olszewski-Jubelirer, J., and Thompson, J.T. (2018). Shape, size, and structure affect obliquely striated muscle function in squid. Int. Comp. Biol. 58, 261-275. doi:10.1093/icb/icy053.

Suction adhesion in gliding joints

Andy Smith, Scott LaValva, Matt Loiacono, and I investigated the structure and function of an interesting joint, the nuchal joint, found in squid. The joint’s function is unclear but it allows the head to glide toward and away from the mantle. Interestingly, while the head glides along the joint with ease, the joint can be disarticulated perpendicular to the axis of movement with the application of considerable force. After disarticulation, the joint components can be repositioned and full function restored immediately. Through a series of biomechanical experiments combined with morphological analysis of joint anatomy, we determined that the joint's function depends upon suction adhesion.

Related recent publication:

Smith, A.M., LaValva, S.M., Loiacono, M.M., and Thompson, J.T. (2019). Suction adhesion in the gliding joint of a cephalopod. J. Exp. Biol. 223, jeb211227. doi:10.1242/jeb.211227.

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