Evolutionary Origin of the Neural Crest

关于神经嵴的进化起源知之甚少，神经嵴是一群迁移的胚胎细胞，在脊椎动物胚胎中有着惊人的多样性。 在这里，杰弗里博士建议继续一项研究计划，确定潜在的同源神经嵴细胞的海鞘Ecteinascidia turbinata，被囊脊索动物代表一组海洋动物，可能是脊椎动物的姐妹组。 他先前获得的证据表明，在这种海鞘物种中存在神经嵴样细胞（NCLC），其基础是从背侧胚胎中线的细胞迁移，神经嵴标记物的表达，与类似基板的结构的关联，与神经嵴细胞合作形成许多脊椎动物的特征，并分化为体色素细胞，这是脊椎动物神经嵴的主要衍生物之一。 这些研究是由通常大尺寸的Ecteinascidia胚胎和幼虫，这允许合并的分子与经典的方法来识别候选人的神经嵴样细胞（NCLC）的促进。 在这里，他建议继续在Ecteinascidia和模式海鞘Ciona Ciona中进行这些研究，他最近也发现了NCLC。 总体目标是通过探索海鞘NCLC和脊椎动物神经嵴细胞的胚胎起源、脊椎动物神经嵴关键调控基因的表达模式、迁移途径和发育命运来评估海鞘NCLC和脊椎动物神经嵴细胞具有共同祖先的假设。 此外，他将通过比较Ecteinascidia和Ciona中的这些特征来探索海鞘中NCLC的多样性，这些特征是具有高度不同形态和生活史的相关物种。 这项研究将继续将联合收割机经典的胚胎学方法（例如细胞谱系、细胞迁移和通过活体染料标记进行发育命运分析）与分子方法（包括基因表达分析）相结合。 在玻璃海鞘中，基因组计划和cDNA数据库的存在以及转基因的机会将促进这些目标的实现。 这些研究将提供深入了解神经嵴细胞的进化起源和历史，海鞘NCLC的命运和多样性提供新的信息，确定海鞘NCLC和脊椎动物神经嵴细胞之间的相似性和差异，并有助于了解脊椎动物从无脊椎动物脊索动物祖先的进化。 这项研究的广泛影响是研究和高等教育的持续整合，这是通过让本科生参与原创性研究，通过培训博士前和博士后研究人员，以及我们对高中科学课程的推广来实现的。 所有这些活动都包括不同性别和代表性不足的少数群体。该实验室将继续是一个有用的和高度赞赏的本地资源，用于教学和说明进化生物学高中学生，也将继续作为他们的短期监督科学项目的资源。 神经嵴的进化是一个很好的例子，说明了形态学上的变化是实验上容易处理的，发生在我们自己的门内，并且通过传统的进化理论被解释为一种新奇的东西。 除了与实验室研究直接相关的广泛影响外，他将继续参与与中小学教育和非专业公众教育有关的外展活动，包括解释支持进化论的科学证据并突出在该领域工作的科学家的开创性工作的广播和电视广播，并担任顾问，为公众（自然历史杂志）和天才儿童（缪斯杂志）策划和撰写关于进化的文章。

Little is known about the evolutionary origin of the neural crest, a population of migratory embryonic cells with an amazing variety of derivatives in vertebrate embryos. Here, Dr. Jeffery proposes to continue a research program that identified potential homologues of neural crest cells in the ascidian Ecteinascidia turbinata, a tunicate chordate representing a group of marine animals that may be the sister group of vertebrates. He previously obtained evidence for the existence of neural crest-like cells (NCLC) in this ascidian species based on following cell migration from the dorsal embryonic midline, expression of neural crest markers, association with structures resembling placodes, which collaborate with neural crest cells to form many vertebrate features, and differentiation into body pigment cells, one of the prime vertebrate neural crest derivatives. These studies were facilitated by the usually large size of Ecteinascidia embryos and larvae, which permitted a merger of molecular with classical approaches for identifying candidates for neural crest-like cells (NCLC). Here he proposes to continue these studies in Ecteinascidia and in the model ascidian Ciona intestinalis, in which he has also recently discovered NCLC. The overall objective is to evaluate the hypothesis that ascidian NCLC and vertebrate neural crest cells had a common ancestry by exploring their embryonic origin(s), the expression patterns of key vertebrate neural crest regulatory genes, their migration pathways, and their developmental fates. In addition, he will explore the diversity of NCLC in ascidians by comparing these features in Ecteinascidia and Ciona, related species with highly divergent morphologies and life histories. This investigation will continue to combine classical embryological approaches, such as cell lineage, cell migration, and developmental fate analysis by vital dye marking, with molecular approaches, including gene expression analysis. In Ciona the objectives will be facilitated by the existence of the genome project and cDNA databases as well as the opportunity of transgenesis. These studies will provide insights into the evolutionary origin and history of neural crest cells, furnish novel information on the fates and diversity of ascidian NCLC, identify the similarities and differences between ascidian NCLC and vertebrate neural crest cells, and help to understand the evolution of vertebrates from an invertebrate chordate ancestor. A broad impact of this research is the continued integration of research and higher education, which is accomplished by involving undergraduate students in original research, by training pre-doctoral and post-doctoral investigators, and by our outreach to high school science programs. All of these activities include different genders and underrepresented minorities. The laboratory will continue to be a useful and highly appreciated local resource for teaching and illustrating evolutionary biology to high school students, and will also continue to serve as a resource for their short supervised science projects. The evolution of the neural crest is an excellent example of a morphological change that is experimentally tractable, has occurred within our own phylum, and is subject to interpretation as a novelty through conventional evolutionary theory. In addition to broad impacts directly related to the laboratory research, he will continue to participate in outreach activities related to primary and secondary school education and education of the lay public, including radio and TV broadcasts that explain the scientific evidence supporting evolution and highlight the seminal work of scientists working in this field, and to serve as advisor in the planning and writing of articles on evolution for the general public (Natural History Magazine) and for gifted children (Muse Magazine).