Evolution: Enhanced Footing for Snake Limb Development
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Using Enclosed Y-Mazes to Assess Chemosensory Behavior in Reptiles
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Maria M Kaltcheva1, Mark Lewandoski1
1Cancer and Developmental Biology Laboratory, National Cancer Institute, Frederick, MD 21702, USA.
Current Biology : CB
|December 7, 2016
Abstract:
Two groups have studied the loss of limbs in snake evolution by focusing on a long-distance cis-acting enhancer of Sonic Hedgehog. They find a progressive degeneration of binding sites for key transcription factors, mirroring the progressive limblessness occurring in these reptiles.
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The mesenchymal stem cells differentiate into chondrocytes that form the hyaline cartilage, and later the cartilaginous model of the bone. This model further transforms into a bone. This process is known as endochondral ossification.
During development, the limbs...