Developmental patterning of the anterior neural plate in a simple chordate

项目总结 海鞘是尾索动物的一员，是海鞘最接近的近亲。 脊椎动物。乔纳蝌蚪为研究长臂猿的进化起源提供了一个良好的系统 脊椎动物的关键创新，如颅骨安慰剂和神经脊。有四个主要的 来自神经板边界的感觉细胞类型，这是安慰剂和 脊椎动物的神经脊。Ciona系统非常适合于阐明基因网络和 四种感觉细胞类型的发育机制：毛细胞 (头部)、表达GnRH的aATEN(躯干)、Patens和BTN(尾部)。详细的理解 这些类型的细胞应该为进化起源和发育提供新的见解 从安慰剂和安慰剂衍生的可比细胞类型规范的基础机制 脊椎动物的神经脊，尤指安慰剂。在之前的资助期内，我们 获得的证据表明，毛细胞和aATEN起源于横跨的原胎盘区域 假定神经管的前缘。AATEN具有双重化学感受性和 神经分泌特性，表明它们代表了一种祖先细胞类型， 细胞亚功能化过程中的特化细胞类型 脊椎动物。Patens和BTN与神经脊的导数有相似之处 脊椎动物，如背根神经节。拟议中的目标有两个 研究：(I)探索毛细胞的规格、分化和相关性，aATEN， Patens和BTN；以及，(Ii)探索细胞的过程 亚功能化，在Ciona中，祖先的感觉细胞类型产生了多个专门的 脊椎动物中形成神经元回路的细胞类型。

PROJECT SUMMARY The sea squirt Ciona intestinalis is member of the urochordates, the closest living relatives of the vertebrates. Ciona tadpoles provide a favorable system for studying the evolutionary origins of key vertebrate innovations such as cranial placodes and neural crest. There are four major sensory cell types that arise from the neural plate border, which is the source of placodes and neural crest in vertebrates. The Ciona system is ideally suited to elucidate the gene networks and developmental mechanisms underlying the specification of all four sensory cell types: hair cells (head), GnRH-expressing aATENs (trunk), pATENs and BTNs (tail). The detailed understanding of these cell types should provide new insights into the evolutionary origins and developmental mechanisms underlying the specification of comparable cell types derived from placodes and neural crest in vertebrates, particularly placodes. During the preceding funding period we obtained evidence that the hair cells and aATENs arise from a proto-placodal territory straddling the anterior border of the presumptive neural tube. The aATENs possess dual chemosensory and neurosecretory properties, suggesting they represent an ancestral cell type that produced specialized cell types through a process of “cellular subfunctionalization” during the evolution of the vertebrates. The pATENs and BTNs possess similarities with derivatives of the neural crest in vertebrates, such as dorsal root ganglia. There are two over-arching goals of the proposed study: (i) explore the specification, differentiation, and relatedness of hair cells, aATENs, pATENs, and BTNs in the Ciona tadpole; and, (ii) explore the process of cellular subfunctionalization, whereby ancestral sensory cell types in Ciona produce multiple specialized cell types forming neuronal circuits in vertebrates.