Molecular mechanisms underlying larval tail regenration in Xenopus Laevis

本研究以非洲爪蟾（Xenopus laevis）幼虫尾部为模型系统，探讨器官再生的分子机制。获得了以下结果。1.溴脱氧尿苷细胞标记实验和形态学观察表明，再生尾的脊髓、脊索和肌肉组织由各组织来源的细胞组成。2.通过原位杂交和RT-PCR方法对基因表达进行分析，发现许多基因在尾发育和尾再生过程中都有表达，而一些基因如chordin和noggin在尾再生过程中不表达。3.原位杂交和动物帽功能分析表明，在再生尾中存在Xwnt-5a活性从远侧到近侧的梯度。Xwnt-5a在幼虫尾部切口处的异位表达诱导了异位尾的形成，表明Xwnt-5a在尾再生的前后模式中具有指导作用。4.使用包括来自再生尾的cDNA的cDNA阵列的差异杂交导致鉴定在尾再生过程中上调的8个基因。

This research was performed to understand molecular mechanisms underlying organ regeneration using larval tail of Xenopus laevis as a model system. The following results were obtained. 1.Cell labeling experiment using bromodeoxyuridine and morphological observation suggested that spinal cord, notochord and muscle tissue in the regenerated tail were formed with cells derived from each tissue. 2.Gene expression analysis by in situ hybridization and RT-PCR methods revealed that many genes were expressed in both the tail development and the tail regeneration processes while some genes, for example, chordin and noggin were not expressed in the tail regeneration process. 3.In situ hybridization and functional analysis using animal cap suggested a presence of a distal to proximal gradient of Xwnt-5a activity in the regenerating tail. Ectopic expression of Xwnt-5a in a dorsal incision on larval tail induced an ectopic tail formation, suggested an instructive role of Xwnt-5a in anterior-posterior pattering of the tail regeneration. 4.Differential hybridization using a cDNA array including cDNAs derived from the regenerating tail resulted in identification of eight genes up-regulated in the tail regeneration process.