Marty Shankland

Marty Shankland

	Professor Ph.D. University of California, Berkeley, 1982 hastypig@mail.utexas.edu Office PAT 602 (512) 232-1892 Shankland Lab home page


Our lab investigates the evolution of animal body plans through a comparative analysis of the developmental mechanisms that shape the early stages of animal embryogenesis. Most of our work involves annelid worms, particularly the leech Helobdella. Annelids are members of the superphylum Lophotrochozoa, and our primary goal is to reveal the degree to which the developmental patterning mechanisms employed by annelids and other lophotrochozoans are similar to or different from those employed by 'model' organisms such as Drosophila, C. elegans or vertebrates, all of which belong to other superphyla. Some patterning mechanisms (e.g. the Hox gene cluster) are conserved among all of these animals, and represent evolutionary homologies that have been inherited from the last common ancestor - in this case, a primitive animal that lived > 600 million years ago and was situated at or near the base of the bilaterian radiation. But many features of that ancestor are in dispute. Was it segmented along the anteroposterior body axis? What genetic mechanism(s) patterned its dorsoventral body axis? How did the distinctive axial properties of the 'bilaterian' body plan first evolve from a non-bilaterian progenitor? By elucidating the cellular and molecular mechanisms that shape annelid embryos and comparing them to the developmental mechanisms found in other living bilaterians, we are steadily gaining new insight into the nature of the earliest bilaterian ancestors and way in which developmental mechanisms have evolved over the course of animal phylogeny.

Selected Publications Nardelli-Haefliger, D., Bruce, A.E.E., and Shankland, M. (1994). An axial domain of HOM/Hox gene expression is formed by morphogenetic alignment of independently specified cell lineages in the leech Helobdella. Development 120, 1839-1849. Kourakis, M.J., Master, V.A., Lokhorst, D.K., Nardelli-Haefliger, D., Wedeen, C.J., Martindale, M.Q., and Shankland, M. (1997). Conserved anterior boundaries of Hox gene expression in the central nervous system of the leech Helobdella. Dev. Biol. 190, 284-300. Wedeen, C.J., and Shankland, M. (1997). Mesoderm is required for the formation of a segmented endodermal cell layer in the leech Helobdella. Dev. Biol. 191, 202-214. Bruce, A.E.E., and Shankland, M. (1998). Expression of the head gene Lox22-Otx in the leech Helobdella and the origin of the bilaterian body plan. Dev. Biol. 201, 101-112. Shankland, M., and Seaver, E.C. (2000). Evolution of the bilaterian body plan: what have we learned from the annelids? Proc. Nat. Acad. Sci. USA. 97, 4434-4437. Seaver, E.C., and Shankland, M. (2000). Leech segmental repeats develop normally in the absence of signals from either anterior or posterior segments. Dev. Biol. 224, 339-353. Seaver, E.C., and Shankland, M. (2001). Establishment of segment polarity in the ectoderm of the leech Helobdella. Development 128, 1629-1641.

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