Kimberly L. Cooper, "Development and evolution of form in the vertebrate limb"
Feb 13, 2013 (Wed) | 12:00 PM -2:00 PM
318 Campus Drive West : Stanford, CA
How are the size and shape of a tissue established in animal development and evolution? To address this question, my research has focused on two projects that harness the strengths of multiple species to study the developing limb. Through the pairing of an in vitro culture system with chick embryo manipulation, I showed that the proximal-distal axis of the limb skeleton (from the shoulder to the fingertips) is established in response to a complex and dynamic signaling environment. The second project has led to the establishment of a new vertebrate system that allows me to investigate the molecular mechanisms underlying evolution of limb morphology. The three-toed jerboa is a bipedal desert rodent with unique hindlimb adaptations including loss of the lateral toes and dramatic elongation and fusion of the remaining metatarsals into a single bone. Using this system to study the mechanisms of differential skeletal elongation, I identified three distinct phases of growth plate chondrocyte enlargement including a surprising phase of cell swelling. It is, however, the final Igf1-dependent phase of mass production that results in the differences in cell volume, and thus elongation rate, between growth plates. Current work has shifted focus to understanding the mechanisms of digit loss, which appears to employ a sculpting away by apoptosis of lateral tissue that would otherwise form correctly patterned lateral digits. Long-term future directions will reveal the mechanisms of genome evolution driving these and other morphological adaptations.
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