TGF-beta and axis formation in Helobdella, a lophotrochozoan

描述（由申请人提供）：PI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变化的演变。为此目的，我们比较了现存生物体的发展相对于“生命之树”（进化），他们出现。不同生物体之间的比较也有助于确定在遗传模式生物中发现的哪些发育特征更有可能在人类中发挥作用，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（环节动物门，分节蠕虫）属于Lophotrochozoa超门，是基于物种间DNA和蛋白质序列比较的新兴生殖发育中的三组双边对称动物之一。Lophotrochozoa包括现存门的大约一半，包括非无腔扁形虫，软体动物和环节动物。然而，大多数发展方面的研究涉及脊椎动物（次口动物超门）、线虫或果蝇（均属于蜕皮动物超门）。包括脊轮藻物种将增加比较发展的广度和力量。使用水蛭Helobdella是因为它的胚胎是许多Lophotrochozoan物种中研究得最好的。它也有一个紧凑的基因组。因此，Helobdella与多毛类蠕虫（Capitella）和软体动物（Lottia）一起沿着，是该部门选择进行全基因组测序的3种Lophotrochozoans之一。能源联合基因组研究所协同发展和基因组分析内和这3个物种之间将有助于了解基因组和发育变化之间的联系。具体来说，拟议的研究是阐明TGF？通路在早期水蛭胚胎中的作用，使用原位杂交和RT-PCR研究基因表达，加上细胞内注射谱系示踪剂和mRNA或反义吗啉代寡聚体，以比较正常胚胎中的细胞命运与TGF？通路被破坏的胚胎。拟议的实验将有助于理解TGF β信号如何指定果蝇的背侧命运，但在脊椎动物的腹侧命运。他们还将有助于理解被称为上皮间质转化（EMT）的细胞过程，这在正常发育和癌症转移中起着关键作用。

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.