ID OF GENES DIFFERENTIALLY EXPRESSED IN DEVELOPING EMBRYONIC LIMB BUDS

阐明和鉴定建立一种新的基因， 形态发生过程中的模式形成及其调控研究 是脊椎动物生物学许多方面的核心问题。它 可以预期包括对营养刺激的反应的过程， 细胞-细胞相互作用，迁移，差异细胞增殖， 程序性细胞死亡等等都有关系。许多相同的过程 在肿瘤发生过程中以病理方式重现。鸡肢 发展是一个有吸引力的系统，研究分子基础， 形态发生过程中的图案形成。一级的重大事件 涉及图案形成的组织/细胞相互作用已经很好地 在这种生物体中，调节模式形成的事件 似乎总体上与哺乳动物系统中的那些非常相似， 系统易于进行生物化学和分子分析， 涉及显微外科操作的研究。 这个长期项目的目的是分离出调节 鸡胚肢芽的形态发生。两种一般类型的方法 正在开发，以实现这一目标：1）减代 富集潜在调控和诱导基因的cDNA文库;和2） 鉴定保守基因家族的相关/新成员， 在其他的发育调节过程中也有牵连， 系统.目前，同源异型盒基因家族的两个新成员已经被发现。 它们在早期的肢芽中选择性地表达， 发展这些基因之一是表达在一个梯度的方式沿着 四肢的A-P轴，翼比腿多4 - 5倍 芽，这表明可能的作用，在模式形成和/或 确定肢体类型身份。第二个基因似乎是 选择性地在发育中的肢芽中表达， 在后来的形态发生事件中，如重塑。

The elucidation and characterization of genes necessary for establishing pattern formation during morphogenesis and the study of their regulation are problems which are central to many aspects of vertebrate biology. It may be expected that processes including responses to trophic stimuli, cell-cell interactions, migration, differential cell multiplication, programmed cell death, etc. are all involved. Many of these same processes are recapitulated in a pathologic manner during oncogenesis. Chick limb development is an attractive system for studying the molecular basis for pattern formation during morphogenesis. Critical events at the level of tissue/cellular interactions involved in pattern formation have been well characterized in this organism, the events regulating pattern formation appear to be overall very similar to those in mammalian systems, and this system is readily amenable to biochemical and molecular analysis as well as studies involving microsurgical manipulation. It is the aim of this long-term project to isolate genes that regulate morphogenesis in the chick embryo limb bud. Two general types of approaches are being developed to achieve this aim: 1) the generation of subtracted cDNA libraries enriched for potential regulatory and induced genes; and 2) the identification of related/new members of conserved gene families that have been implicated in developmental regulatory processes in other systems. Currently, two new members of the homeobox gene family have been identified which are selectively expressed in limb buds during early development. One of these genes is expressed in a graded fashion along the A-P axis of the limb and is 4 to 5 fold more abundant in wing than leg buds, suggesting possible roles in pattern formation and/or the determination of limb-type identity. The second gene appears to be selectively expressed later in developing limb buds and might play a role in later morphogenetic events such as remodeling.