Reptilian tooth and jaw development

点击翻译按钮获取中文摘要

This grant will study the formation of the teeth and jaws of reptiles. The first aim we will study the genes involved in replacement of teeth. Rodents are the most common model to study tooth development but their weakness is that they only have one set of teeth. To overcome this problem the proposed research use snakes and lizards that replace their teeth throughout life. In previous studies, we identified a network of signaling factors that control tooth initiation in pythons and geckos. Now we will add in two more signaling pathways and will expand our studies to later stages of tooth replacement. The importance of studying this question is that we will understand why some orders of animals have lost the ability to replace their teeth, while others form multiple sets. We will also address the contribution of 'stem cells' to tooth replacement. Our previous work suggested that putative stem cells are present in gecko teeth. Here we will activate these putative stem cells and follow their contributions to replacement teeth. The second aim of the grant will focus on skull development. Our preliminary studies have shown that the palates of snakes, lizards and birds are quite similar to mammals since they all pass through a similar intermediate stage. In contrast, turtles lack the transient structures called palatal shelves, yet the palatine bones still form and meet in the midline. The proposed experiments here will discover how the turtle palate is formed by taking a different developmental path. Finally we will be addressing the embryonic origins of the unique and ancient turtle skull shape. We will identify a group of genes that are different in the turtle versus the chicken and then we will test whether they are sufficient to make the bird skull more like that of the turtle. In summary, our application of current developmental biology techniques to reptiles will provide a wealth of new insights into evolution including why humans and other mammals are limited to 2 sets of teeth and whether or not turtles are the most primitive reptile order.