Evolution of Gene Regulatory Networks for Development of Novel Structures in Echinoderm Embryos

动物形态的巨大多样性是由于基因组的变化改变了发育的程序;然而，这种变化的确切性质知之甚少。 由于许多技术原因，海胆胚胎发育的遗传基础非常清楚，特别是形成幼虫骨架的细胞谱系。 这种细胞谱系是一种进化上的新奇事物，因为它在其他与海胆有关的动物（例如海星和海参）的胚胎中没有发现。 这提供了一个特殊的机会来了解在进化过程中如何发生调节变化，以允许开发一个全新的形态。 除了一个基因外，所有制造海胆骨骼谱系所需的相同（orthopathy）基因也在海星星胚胎中表达。 这些初步数据表明，这种发育上的新奇性并不是因为获得了新的基因，而是因为这些基因的功能发生了变化。 该项目将确定这些正交基因在海星星胚胎中的调节相互作用，以了解它们的功能如何在海胆中进化。 将使用各种分子方法干扰基因产物，并确定对其他基因的发育和表达的影响。 还将进行一系列跨物种实验，将海星的基因产物注入海胆胚胎，反之亦然。 这些实验将直接确定基因功能是否发生了进化变化，以及这些变化如何改变发育。 这个项目将提供一个高度机械的理解，基因功能的进化变化如何导致新结构的发展，并将提供密集的研究经验，为几个本科生和一个女研究生。

The great diversity of animal morphology is due to genomic changes that alter the programming of development; however, the exact nature of such changes is poorly understood. For many technical reasons the genetic basis of development is extraordinarily well understood in sea urchin embryos, especially that of a cell lineage that will form the skeleton of the larva. This cell lineage is an evolutionary novelty as it is not found in the embryos of the other groups of animals related to the sea urchin (e.g. sea stars and sea cucumbers). This provides the exceptional opportunity to understand how regulatory changes have occurred during evolution to allow the development of an entirely novel morphology. All of the same (orthologous) genes, with the exception of just one, that are needed to make the sea urchin skeleton lineage are also expressed in the sea star embryo. This preliminary data demonstrates that this developmental novelty, therefore, is not due to the acquisition of new genes, but rather a change in the way in which these same genes function. This project will determine the regulatory interactions between these orthologous genes in sea star embryos in order to understand how their function has evolved in the sea urchin. Gene products will be perturbed using various molecular approaches and the effect on development and expression of other genes will be determined. A series of cross-species experiments will also be undertaken, where gene products from sea stars will be injected into the embryo of the sea urchin and vice versa. These experiments will directly determine whether there has been an evolutionary change in gene function and how any such changes alter development. This project will provide a highly mechanistic understanding of how evolutionary changes in gene function can lead to the development of novel structures and will provide intensive research experiences for several undergraduates and a woman graduate student.