The Non-Vertebrate Chordate Oikopleura and Evolution of Vertebrate Developmental Innovations

脊椎动物脊索动物具有非脊椎动物脊索动物所没有的创新，包括神经嵴、神经源性基板、骨骼特征和扩增的基因组。该项目的长期目标是了解脊椎动物如何从非脊椎动物脊索动物进化而来。这项工作测试了这样的假设：脊椎动物进化出了神经板边缘基因打开神经嵴指定器的能力。该项目在 Oikopleura dioica 中测试了这一假设的预测，Oikopleura dioica 是一种基因组完全测序的幼虫，使用新颖的方法同时改变数百个胚胎。幼虫是普遍存在的海洋生物，被认为是对海洋生物量和碳循环做出重大贡献的基础脊索动物。 将克隆神经嵴相关基因的 Oikopleura 直向同源物，并使用原位杂交来了解它们的表达模式。将通过对关键嵴相关基因的 Oikopleura 直系同源物进行功能获得和丧失功能实验来剖析 Oikopleura 中的神经嵴相关基因调控网络，并对原位杂交和基因组微阵列的结果进行评估。公众对幼虫在环境中和脊椎动物起源调查中的作用的了解将得到加强。实现这些目标将定义脊椎动物进化为发育成熟的神经嵴的发育机制，并阐明进化新颖性产生的机制。由于幼虫，特别是 Oikopleura dioica，从大气中清除大量温室气体二氧化碳，并长期储存在海洋深处，因此更好地了解幼虫生物学将有助于阐明对全球变暖的理解。该项目将教育学生了解幼虫在生态学和进化生物学科学中的作用，并将指导代表性不足的群体的代表，特别是少数族裔本科生。

Vertebrate chordates have innovations not shared by non-vertebrate chordates, including neural crest, neurogenic placodes, skeletal features, and an amplified genome. The project's long-term objective is to learn how vertebrates evolved from non-vertebrate chordates. This work tests the hypothesis that vertebrates evolved the ability of neural plate border genes to turn on neural crest specifiers. The project tests predictions of the hypothesis in Oikopleura dioica, a larvacean with a fully sequenced genome, using novel methods to alter hundreds of embryos at once. Larvaceans are ubiquitous marine organisms that are considered basal chordates that contribute substantially to the biomass and carbon cycling of oceans. Oikopleura orthologs of neural crest-related genes will be cloned and in situ hybridization will be used to learn their expression patterns. Neural crest-related gene regulatory networks in Oikopleura will be dissected by performing gain- and loss-of-function experiments with Oikopleura orthologs of key crest-related genes, and results by in situ hybridization and genomic microarray will be evaluated. Public understanding will be enhanced of the roles of larvaceans in the environment and in the investigation of vertebrate origins. Achieving these aims will define developmental mechanisms that vertebrates evolved to develop a full blown neural crest and illuminate mechanisms by which evolutionary novelties arise. Because larvaceans, especially Oikopleura dioica, remove large quantities of the greenhouse gas carbon dioxide from the atmosphere for long-term storage in ocean depths, a better understanding of larvacean biology will help illuminate understanding of global warming. The project will educate school children about the role of larvaceans in ecology and the science of evolutionary biology and will mentor representatives of underrepresented groups, particularly minority undergraduates.