IDENTIFICATION OF GENES REGULATING DEVELOPMENT OF EMBRYONIC LIMB BUDS

建立模式形成所必需的基因的鉴定 在形态发生过程中，以及对其调节的研究是一个问题， 对脊椎动物生物学的许多方面都至关重要。 许多关键过程， 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，也以病理的方式重现， 肿瘤发生 鸡肢发育是一个很有吸引力的研究系统 图案形成的分子基础，因为在 图案形成中涉及组织/细胞相互作用的水平 已被充分表征，似乎与哺乳动物中的那些非常相似 系统，并且该系统易于进行生物化学和分子生物学分析。 分析以及显微手术操作。 这个长期项目的目的是分离出调节 鸡胚肢芽的形态发生。 两种一般方法是 正在开发：1）产生富集的消减cDNA文库， 潜在的调控和诱导基因; 2）识别 相关/新成员的保守基因家族，已牵连在 其他系统中的发育调节过程。 目前，两个新 同源异型盒基因家族的成员已经被鉴定， 在早期发育过程中主要在肢芽中表达。 这些基因 每一个都在肢芽内显示出空间受限的表达域， 提示其在沿着前位调节图案形成中的作用 (A-P)和肢体的近远轴（P-D）。 其中一个同源异型盒 基因还显示翅芽和腿芽之间的表达差异， 表明它也可以调节肢型身份的确定。 研究正在进行中，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.