IDENTIFICATION OF GENES REGULATING DEVELOPMENT OF EMBRYONIC LIMB BUDS

建立模式形成所需基因的鉴定 在形态发生及其调控的研究中存在着一些问题 是脊椎动物生物学许多方面的核心。中的许多关键流程 形态发生，包括对营养刺激的反应，细胞-细胞 相互作用、迁移、差异细胞增殖、程序化细胞 死亡，等等，也是以病理的方式在 致癌作用。雏鸡肢体发育是一个很有吸引力的研究系统 花纹形成的分子基础是因为 参与图案形成的组织/细胞相互作用的水平 有很好的特征，看起来与哺乳动物的非常相似 系统，而且这个系统很容易受到生化和分子的影响 分析以及显微外科操作。 这项长期计划的目标是分离出调节 鸡胚胎肢芽的形态发生。两种常见的方法是 正在开发：1)丰富的消减cDNA文库的生成 寻找潜在的调控和诱导基因；以及2)鉴定 保守基因家族的相关/新成员，已牵涉到 其他系统中的发育调控过程。目前，有两个新的 同源异型盒基因家族的成员已经被确定，它们是 在发育早期主要在肢芽中表达。这些基因 每一个都在肢芽中显示了空间受限的表达区域， 提示在调节前位花纹形成中的作用 (A-P)和近端(P-D)轴。这些同源盒子中的一个 基因还显示出翼芽和腿芽之间的表达差异， 这表明它还可能调节肢体类型身份的确定。 目前正在进行研究，以阐明这些调控基因的功能， 使用分子遗传学和生物化学方法。

The identification 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. Many key processes in morphogenesis, including responses to trophic stimuli, cell-cell interactions, migration, differential cell multiplication, programmed cell death, etc., are also recapitulated in a pathologic manner during oncogenesis. Chick limb development is an attractive system for studying the molecular basis of pattern formation because critical events at the level of tissue/cellular interactions involved in pattern formation have been well characterized and appear to be very similar to those in mammalian systems, and this system is readily amenable to biochemical and molecular analysis as well as 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 approaches are being developed: 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 expressed predominantly in limb buds during early development. These genes each show spatially restricted expression domains within the limb bud that suggest roles in regulating pattern formation along the anterior-position (A-P) and proximodistal (P-D) axes of the limb. One of these homeobox genes also displays expression differences between wing and leg buds, indicating it may also regulate the determination of limb-type identity. Studies are underway to elucidate the function of these regulatory genes, using both molecular genetic and biochemical approaches.