Amphibian Models for Bodywall Patterning

描述（由申请人提供）：迄今为止，研究者的工作已经在发育中的脊椎动物胚胎中确定了两个动态的中胚层区域。原域完全由来自体点的细胞组成。腹侧区由体体的成肌细胞和肌肉分化的侧板结缔组织组成。他们把这两个域之间的边界称为侧体边界（LSF）。这个新术语避免了在提及胚胎种群时由于功能术语外轴/下轴引起的混淆。研究人员利用鹌鹑-小鸡嵌合体部分绘制了小鸡的LSF图谱，最近绘制了小鼠的边界图谱（Durland et al., 2008）。这些边界的一瞥揭示了在成虫形态中隐藏的下/上边界。有趣的是，这些隐域与不同的自然和实验小鼠突变体的影响分布一致。据推测，LSF是早期信息交换的场所，这对脊椎动物身体的正常模式至关重要。这里提出的工作将把我们关于LSF的知识扩展到常见的两栖动物模型，青蛙（Xenopus）和蝾螈（Ambystoma-axolotl）系统。利用新的绿色荧光蛋白转基因在青蛙和蝾螈物种，研究人员将首先使用同位素移植来绘制这些羊膜动物的体-侧板界面，其次，使用异位体移植来验证边界代表图案边界的假设。两栖动物为直接实验方法提供了明显的优势。本项目的长期目标是建立GFP转基因两栖动物系统，用于测试重要胚胎事件期间组织相互作用的假设。医学依赖于模型系统间外推实验结果的有效性。两栖动物研究体壁形成的优势包括：相对于羊膜系统，其胸腹体壁相对简单；较大的细胞尺寸便于混合谱系群体的识别；以及爪蟾丰富的分子和发育技术。更全面地了解我们所有共同模型系统中中胚层种群之间的动态相互作用将增加实验结果的相关性和价值。

DESCRIPTION (Provided by Applicant): The investigators' work to date has identified two dynamic mesodermal domains in the developing vertebrate embryo. The primaxial domain is populated exclusively by cells from the somites. The abaxial domain is made up of myoblasts from the somites and connective tissue of the lateral plate in which the muscles differentiate. They have termed the boundary between the two domains the lateral somitic frontier (LSF). This new terminology avoids the confusion caused by the functional terms epaxial/hypaxial when referring to embryonic populations. The investigators have partially mapped the LSF in the chick using quail-chick chimeras and more recently mapped the frontier in the mouse (Durland et al., 2008). These glimpses of the frontier revealed abaxial/primaxial boundaries that are cryptic in adult morphology. Interestingly, these cryptic domains are consistent with the distribution of the impact of different natural and experimental mouse mutants. It is hypothesized that the LSF is the site of early information exchange that is crucial for normal patterning of the vertebrate body. The work proposed here will extend our knowledge about the LSF into the common amphibian model, the frog (Xenopus) and salamander (Ambystoma-axolotl) systems. Taking advantage of new GFP transgenics in both frog and salamander species, the investigators will first use isotopic transplants to map the somitic-lateral plate interface in these anamniotes, and second, use heterotopic somite transplants to test the hypothesis that the frontier represents a patterning boundary. Amphibians offer distinct advantages for direct experimental approaches. The long-term goal of this project is to establish the GFP transgenic amphibians as systems for testing hypothesis about tissue interactions during important embryonic events. Medical science depends on the validity of extrapolating experimental results among model systems. The advantages of amphibian species for studying body wall formation include the relative simplicity of the thoracic and abdominal body wall relative to amniote systems, the large cell size facilitating identity of mixed lineage populations, and the abundant molecular and developmental techniques already available in Xenopus. A fuller understanding of the dynamic interactions among mesodermal populations in all of our common model systems will increase the relevance and value of experimental results. NARRATIVE: This work investigates body wall formation in vertebrate embryos. Errors in the complex interactions of the embryonic tissues that form the ribcage and body wall result in birth defects in the human population. The proposed experiments seek to understand the dynamics of mesodermal tissue interactions using morphologically simple amphibian model systems.