Susan V. Bryant 

Ph.D., University of London, 1967
Molecular basis of limb development and regeneration
Email address: svbryant@uci.edu 


Alone among vertebrates, urodele amphibians are able to regenerate lost body parts as adults. The key to this ability is that limb cells are triggered to dedifferentiate and reinitiate growth and pattern formation. Our strategy is to use axolotls (Ambystoma mexicanum) to discover the signals that trigger the regeneration response, in the belief that these signals have enormous potential and consequences for human health. Our long term goals are to identify the regeneration-enabling signals in limbs, in order to support progress towards the eventual application of these molecules to the improvement of human repair mechanisms.  In current research, we are using assays derived from the extensive experimental history of regenerating limbs, to test the roles of several signaling molecules known to be essential for limb development. These assays use virally-driven ectopic expression to examine the signals that initiate regeneration, those that are needed to establish a blastema, as well as those that are required for intercalary growth between the new limb tip and the amputation plane.  In addition, we are generating  a library of arrayed cDNAs made from regenerating limbs at different stages.  The library will be screened with stage specific probes to identify genes expressed at different times in regeneration.  We are especially interested in any novel factors that might be involved in transforming the differentiated limb stump into a blastema.  The tools and knowledge are in place to attack complex systems, and understanding regeneration is likely to lead to new approaches and therapies for replacing or repairing lost, damaged or diseased parts of the body.

Lab Page

Selected Publications 

Ohsugi,  K.,  Gardiner, D.M. and  Bryant, S. V. (1997).  Cell cycle length affects gene expression and pattern formation in limbs. Dev. Biol.189,13-21.

Mescher, B. D., Northcutt, R. G. Gardiner, D. M. and Bryant, S. V. (1997). Homeobox  genes in axolotl lateral line:  Development and maintenance. Dev Genes and Evol, 207, 287-295

Carlson, M. R. J., Bryant, S. V. and Gardiner, D. M. (1998).  Expression of Msx-2 during   development, regeneration and wound healing in axolotl limbs. J.E.Z.  282:715-723.

Gardiner, D. M., Torok, M., Mullen, L. M. and Bryant, S. V. (1998). Evolution of vertebrate limbs: Robust morphology and flexible development. Am. Zool., 38, 659-671

Gardiner, D.M. and Bryant, S.V. (1998). The Tetrapod Limb. In "Cellular and Molecular Basis of Regeneration: from invertebrates to humans", Ferretti, P. and Geraudie, J. (eds). John Wiley & Sons, Ltd. Chichester. pp. 187-205.

Torok, M.A., Gardiner, D.M., Shubin, N.H., Bryant, S.V. (1998) Regulation of HoxD expression in developing and regenerating axolotl limbs. Dev. Biol. 200, 225-233

Bryant, S. V. (1999). Guest Editor: A Regeneration Renaissance. Sem. in Cell & Dev Bio , 10

Mills, A.A., Mills, M., Gardiner, D.M., Bryant, S.V., and Stanbridge, E.J. (1999). Expression of QM  during embryogenesis of the mouse. Differentiation 164, 161-171.

Torok, M.A., Gardiner, D.M., Izpisua-Belmonte, J.C., and Bryant, S.V. (1999). Analysis of Sonic Hedgehog (shh) expression in developing and regenerating axolotl limbs. J. Exp. Zool. 284, 197-206.

Yang, E. V., Nugas, C. A., Gardiner, D. M., Carlson, M. and Bryant, S. V. (1999)   Expression of Mmp-9 and other matrix metalloproteinase genes during axolotl limb regeneration. Dev Dynam. 216, 2-9.

Roy, S., Gardiner, D.M. and Bryant, S.V. (2000). Vaccinia as a tool for functional analysis in regenerating limbs: ectopic expression of Shh. Dev. Biol. 218, 199-205.

Carlson, M.R.J., Komine, Y., Bryant, S.V., and Gardiner, D.M. (2001). Expression of Hoxb13 and Hoxc10 in developing and regenerating axolotl limbs and tails. Dev. Biol. 229, 396-406.