Improving Older Metamorphic Xenopus Tadpole Hindlimb Regeneration Quality

Jo Ann Cameron

University of Illinois College of Medicine
Department of Cell and Structural Biology
B107 Chemical and Life Sciences Laboratory
601 S. Goodwin, Urbana IL 61801

The ability to regenerate hindlimbs and parts of limbs perfectly declines as Xenopus laevis tadpoles approach metamorphosis. Younger Xenopus tadpoles with ossified skeletal elements regenerate higher quality limbs than older stage tadpoles. The gradual loss occurs from proximal to distal at any one stage, and at any one proximal-distal location the ability to regenerate perfect limbs declines with age. We have constructed a regeneration baseline to which we can compare regeneration quality statistically from one stage to another at a single proximal-distal level and within a single stage from one proximal-distal level to another. Using the regeneration baseline we are examining the quality of regeneration outcomes after transgenically expressing key genes that are present during limb development and in cases where regeneration quality is high but absent in cases where regeneration quality is low. Sonic hedgehog is not re-expressed in cases where regeneration outcome is predictably poor. Transgenic expression of Shh in premetamorphic hindlimb blastemas that would typically give rise to poor regeneration outcomes, results in improved regeneration outcomes. Sonic hedgehog expression is directly correlated to improved regeneration quality in Xenopus laevis premetamorphic tadpoles.