Molecular mechanism of vascular system formation

1.对拟南芥维管突变体van1-van7的分子分析表明，这些突变体的缺陷是由原形成层细胞的异常模式形成引起的。此外，我们还表明血管网络的连续性比其整体结构对遗传损伤更敏感，支持扩散-反应前置模式模型。胡萝卜体细胞胚胎发生过程中HD-Zip同源框基因的分析。我们用原位杂交技术分析了6个HD-Zip同源框基因CHB1-CHB6在胡萝卜体细胞胚胎发生过程中的表达模式，发现这些基因在胡萝卜体细胞胚胎发生的后期都与维管细胞相关表达，即CHB6基因在原形成层中特异表达，其他基因在不同的维管细胞中表达。这些结果表明，HD-Zip同源框基因参与了血管的形成。…血管的分析叶肉细胞分化为维管细胞的百日草体外培养体系中，r细胞分化更多。(1)我们发现在百日草体外培养体系中存在不同种类的维管细胞。(2)我们建立了新的培养方法，用这种方法部分纯化了一种管状诱导因子。部分纯化的产物是一种高相对分子质量的阿拉伯半乳糖蛋白，命名为“xylogen”。(3)我们发现油菜素内酯类化合物是在分化阶段3之前合成的，它们的生物合成受到油菜素内酯生物合成编码基因转录的协调增加的调节。此外，我们发现油菜素类固醇是一种活性油菜素类固醇，它优先在细胞外分泌并在培养液中积累，这表明油菜素类固醇类化合物在细胞外表面起作用。(4)利用噬菌体展示消减方法，我们成功地分离到三种识别特定血管细胞细胞壁的新抗体。较少

1. Analysis with Arabidopsis vascular mutants, van1-van7 : Molecular analysis of Arabidopsis vascular mutants, van1-van7 with a pAthb8-GUS or pTED3-GUS fusion gene revealed that defects of these mutants were caused by abnormal pattern formation of procambial cells. In addition, we displayed that the continuity of the vascular network is more sensitive to genetic lesions than their overall architecture is, supporting the diffusion-reaction prepattern model.2. Analysis of the HD-Zip homeobox genes during carrot somatic embryogenesis. We analyzed expression pattern of 6 HD-Zip homeobox genes, CHB1-CHB6, with in situ hybridization during carrot somatic embryogenesis, and revealed that all the genes were expressed in association with vascular cells in the late stage of embryogesesis, that is, CHB6 was expressed specifically in procambium and others were in different vascular cells. These results suggest that the HD-Zip homeobox genes are involved in vascular formation.3. Analysis of vascula … More r cell differentiation with an in vitro Zinnia system in which mesophyll cells differentiate into vascular cells.(1) We revealed the presence of different kind of vascular cells in the in vitro Zinnia culture system.(2) We established new culture methods, with which a tracheary element-inducing factor was partially purified. The partially purified substance was a high molecular weight-arabinogalactan protein and designated "xylogen".(3) We found that brassinosteroids were synthesized prior to Stage 3 of differentiation and their biosynthesis was regulated by a coordinated increase in transcription of genes encoding brassinosteroid biosynthesis. In addition, our finding that castasterone, an active brassinosteroid, is secreted preferentially out of the cell and accumulates in medium, suggests that brassinosteroids function at extracellular surface of the cell.(4) Using a phage display subtraction method, we succeeded in isolating of three novel antibodies recognizing cell walls of specific vascular cells. Less