Mechanism of Region-dependent Metamorphic Tissue Remodeling

(1)获得可用于无尾变态研究的条件转基因蝌蚪的方法。构建了四环素诱导表达的基因表达载体。将该基因导入非洲爪哇蝌蚪皮肤后，该基因以四环素依赖的方式表达。然而，携带这种结构的生殖系转基因蝌蚪在接触激素时未能表达这种结构，尽管有报道称这种试剂可以诱导这种结构。我们认为，需要进一步的技术改进，以稳定和可重复的表达。(2)控制幼虫皮肤区域依赖性变性重塑的基因表达调控。我们已经报道了PDGF/PDGFR信号在蝌蚪皮肤区域依赖性重塑中起关键作用，并认为与该信号相关的基因受HOX基因的控制。我们获得了一些实验证据来支持这一…假说更多的姐姐。(1)Hoxa 13mRNA仅在尾部脊髓表达。(2)在甲状腺激素(TH)存在的情况下，HOXA 13在尾侧脊髓表达增强，导致细胞凋亡加速。然而，这种加速并不是以其显性的负性形式发生的。(3)区域依赖性皮肤重塑相关基因的综合分析。我们对TH处理的幼虫皮肤的总RNA进行了寡核苷酸芯片测试，发现TH分别上调和下调了1,497和962个基因的表达。大约有500个TH早期反应基因的表达水平在TH处理后24小时内发生变化。在电子计算机中，利用热带爪哇的基因组序列数据库，针对这些早期反应基因进行了甲状腺激素反应元件(TrE)的存在分析。结果共鉴定出20个含有tre的基因。Xak-C基因就是其中之一，凝胶漂移分析表明其tre基因具有功能。一些受TH调控的基因在变态过程中的表达谱得到了进一步的表征。较少

(1)Development of a method to yield conditional transgenic tadpoles usable for researches on anuran metamorphosis. An expression gene construct was made, whose expression was inducible by tetracycline. When transfected into Xenopus tadpole skin, the gene in the construct was expressed in an tetracycline-dependent manner. However, germ line-transgenic tadpoles bearing this construct failed to express it when exposed to the hormone, although a report had been published that it was inducible by the reagent. We consider that a further technical improvement is required for stable and reproducible expressions. (2)Regulation of expression of genes that control the region-dependent metamorphic remodeling of larval skin. We had reported that a PDGF/PDGFR signaling plays a key role in the region-dependent skin remodeling of tadpoles and thought that genes associated with the signaling are under the control of Hox genes. We obtained a few lines of experimental evidence that supported this hypothe … More sis. (1)Hoxa 13 mRNA was exclusively expressed in the tail spinal cord. (2)An enforced expression of Hoxa 13 in the tail spinal cord resulted in the acceleration of apoptosis in the presence of thyroid hormone (TH). However, the acceleration did not take place with its dominant negative form.(3)Comprehensive analysis of genes associated with the region-dependent skin remodeling. We made an oligo-microarray test against total RNAs from larval skins treated with TH and identified 1,497 and 962 genes whode expressions were up- and down-regulated by TH, respectively. There were approximately 500 TH-early responsive genes whose expression levels were changeable within 24 hours after TH treatment. In silico analyses for the presence of the thyroid hormone response element (TRE) were performed against these early response genes using genomic sequence databases of Xenopus tropicalis. As a result, 20 genes were identified that contained TRE. Xak-C gene was one of such genes and the gel shift assay indicated that its TRE was functional. A few genes whose expressions were regulated by TH were characterized further in terms of expression profiles during metamorphosis. Less