TGF-beta and axis formation in Helobdella, a lophotrochozoan

描述（由申请人提供）：PI在途中研究的长期目标是了解发育过程调节的变化如何允许身体计划的变化演变。为此，我们将现存生物的发展与它们产生的“生命之树”（系统发育）进行比较。不同生物体之间的比较还应有助于确定在遗传模式生物体中发现的哪些发育特征更可能在人类中起作用，并应阐明发育机制的急性扰动与出生缺陷之间的联系。水蛭（分节蠕虫，环节动物门）属于蛭形动物超门，根据物种间DNA和蛋白质序列的比较，在新兴的系统发育中，水蛭是三组双边对称动物之一。光栖动物大约包括现存门的一半，包括非珊瑚虫扁形虫、软体动物和环节动物。然而，大多数关于发育的研究涉及脊椎动物（后口动物超门）、线虫或果蝇（两者都属于外生动物超门）。包括光栖动物物种将增加比较发展的广度和力量。使用水蛭是因为它的胚胎是许多蛭形动物物种中研究得最好的。它还有一个紧凑的基因组。因此，Helobdella与一种多毛类蠕虫（Capitella）和一种软体动物（Lottia）一起，成为能源部联合基因组研究所选择进行全基因组测序的三种光面动物之一。这三个物种内部和之间的协同发育和基因组分析将有助于了解基因组和发育变化之间的联系。具体而言，本研究旨在阐明TGF¿通路在早期水蛭胚胎中的作用，采用原位杂交和RT-PCR技术研究基因表达，并在细胞内注射谱系示踪剂和mrna或反义morpholino低聚物，比较正常胚胎和TGF¿通路被破坏的胚胎的细胞命运。这些实验将有助于理解TGF¿信号如何在果蝇中决定背侧命运，而在脊椎动物中决定腹侧命运。他们还将有助于理解上皮-间质转化（EMTs）的细胞过程，这在正常发育和癌症转移中都起着关键作用。

DESCRIPTION (provided by applicant): The long term objective of the PI en route's research is to understand how changes in the regulation of developmental processes permit the evolution of changes in body plan. For this purpose, we compare the development of extant organisms with respect to the "tree of life" (phylogeny) by which they arose. Comparisons between diverse organisms should also help to determine which developmental features discovered in genetic model organisms are more likely to be operating in human, and should shed light on the links between acute perturbations of developmental mechanisms and birth defects. Leeches (segmented worms, phylum Annelida) belong to the super-phylum Lophotrochozoa, one of three groups of bilaterally symmetric animals in the emerging phylogeny based on comparisons of DNA and protein sequences between species. Lophotrochozoa includes roughly half of the extant phyla, including non-acoel flatworms, molluscs and annelids. However, most research in development concerns vertebrates (super-phylum Deuterostomia), nematode or fruitfly (both in the superphylum Ecdysozoa). Including lophotrochozoan species will increase the breadth and power of comparative development. The leech Helobdella is used because its embryo is among the best studied of the many lophotrochozoan species. It also has a compact genome. As a result, along with a polychaete worm (Capitella) and a mollusc (Lottia), Helobdella is one of 3 lophotrochozoans selected for whole genome sequencing by the Dept. of Energy's Joint Genome Institute. Synergistic developmental and genomic analyses within and among these 3 species will help to understand the links between genomic and developmental change. Specifically, the proposed research is to elucidate the role(s) of the TGF¿ pathway in the early leech embryo, using in situ hybridization and RT-PCR to study gene expression, plus intracellular injection of lineage tracers and mRNAs or anti-sense morpholino oligomers to compare cell fates in normal embryos with those where the TGF¿ pathways have been disrupted. The proposed experiments will contribute to understanding how TGF¿ signaling specifies dorsal fates in Drosophila, but ventral fates in vertebrates. They will also contribute to understanding the cellular processes known as epithelial-to-mesenchymal transitions (EMTs), which play a critical role both in normal development and in cancer metastasis.