Dissertation Research: Bone Morphogenetic Protein (Bmp) Function in Teleost Dental Evolution and Development

牙齿是组织的例子，在生物体内和物种之间都有变化。控制牙齿形态发育和进化变异的遗传因素尚不清楚。已经发现骨形态发生蛋白（BMPs）基因家族成员的基因表达的时间在不同硬骨鱼物种，特别是斑马鱼和墨西哥河豚的牙齿发育中存在差异。为了测试这些表达差异是否真的导致这些物种牙齿发育的差异，将使用两种策略来改变鱼牙齿发育中BMP基因的表达。首先，将浸泡在Bmp蛋白或Bmp拮抗剂（如noggin）中的珠子应用于鱼胚胎发育中的口腔区域。第二，通过注射吗啉代反义寡核苷酸（阻止正常mRNA加工或翻译的修饰的RNA序列），将使两种鱼类的胚胎中的正常Bmp基因表达失活。 这两种类型的治疗的效果将使用原位杂交的基因可能受到BMP表达的调节。还将使用组织学染色剂检查较老的实验扰动胚胎中的牙齿形态。Bmp基因功能的扰动预计会改变或阻止牙齿的发育，并改变对牙齿发育重要的基因的表达。这项工作的结果将确定Bmp基因在鱼类牙齿发育中的功能，并测试Bmp表达的变化是否可能参与鱼类牙齿发育不同模式的进化。总之，这项工作将阐明脊椎动物形态进化的机制。

Teeth are examples of tissues that vary both within an organism and between species. The genetic factors that govern developmental and evolutionary variations in teeth morphology are unknown. The timing of the gene expression of members of the gene family of bone morphogenetic proteins (Bmps) have been found to differ in developing teeth of different teleost fish species, specifically zebrafish and Mexican tetras. To test whether these expression differences actually cause differences in tooth development in these species, two strategies will be used to alter Bmp gene expression in fish tooth development. First, beads soaked in Bmp proteins or Bmp antagonists (such as noggin) will be applied to the developing oral regions of fish embryos. Second, normal Bmp gene expression will be inactivated in embryos of both fish species by injecting morpholino antisense oligonucleotides (modified RNA sequences which prevent normal mRNA processing or translation). The effects of these two types of treatments will be measured using in situ hybridization for genes likely to be regulated by Bmp expression. The morphology of teeth in older experimentally perturbed embryos will also be examined with the use of histological stains. Perturbation of Bmp gene function is expected to alter or prevent the development of teeth, and to alter the expression of genes important to the development of teeth. The results of this work will determine the function of Bmp genes in tooth development in fishes, and test whether changes in Bmp expression could be involved in the evolution of different patterns of tooth development in fishes. Overall, this work will shed light on mechanisms of morphological evolution in vertebrates.