Transformation of Digit Identity in the Tadpole and Axolotl
The research theme of the Cameron lab focuses on the development and regeneration of the hind limb of tadpoles and axolotls, and the research goal is to change the identity of the digits in the hind limb of these amphibians. It has been determined that during limb development, webbing in-between the developing digits, which is called interdigital mesenchyme, specifies the digit identity in chicks (embryonic chickens) (L. Kaplan et al., 2002). We are using other vertebrates (tadpoles and axolotls) in an experiment to decide whether or not digit identity in amphibians is likewise specified by the mesenchyme between the digits. Moreover, it is pertinent to use both tadpoles and axolotls because their digits form in opposite order during development. The two techniques that are being used in this experiment include surgery and electroporation. In previous experiments, surgical removal of the interdigital mesenchyme of chicks and tadpoles resulted in a 50% transformation of the digit identity of digit #4 to a more anterior type. In contrast, the method of electroporation will be used to inject Sonic Hedgehog (Shh) and Noggin expression plasmids into tadpole and axolotl interdigital mesenchyme. Shh increases the amount of Bone Morphogenic Protein (BMP) signaling, while Noggin decreases it. BMP is responsible for the regulation of digit identity in chicks. Surgical procedures and electroporation are methods that will help to determine whether or not the digit identity is specified equally or very similarly in all vertebrates. One reason why this research is important concerns human finger and toe formation. Certain mutations or other developmental problems can result in fingers that are fused together, too short, or incorrect in number. Understanding the mechanisms involved in digital identity determination may lead to methods that will resolve developmental problems in humans.
School:
Jackson State University
Department:
Biology
Research Advisor:
Jo Ann Cameron
Department of Research Advisor:
Cell and Structural Biology
Year of Publication:
2002