Investigation for Common Molecular Mechanisms by Comparison of EST from Purified Germ Cells

青鳉胚胎是透明的，这使我们能够在体内监测形态发生中发生的发育过程。我们利用生殖系特异表达基因vasa的调控区与绿色荧光基因融合，成功地培育出转基因青鳉。通过这种转基因技术，我们可以观察生殖系的发育，即未来卵子或精子的细胞谱系。我们已经建立了分离几种生殖细胞的技术，并建立了生殖细胞特异表达的EST的cDNA文库，我们最初的目的是比较青鳉和小鼠生殖细胞的EST，以揭示在物种之外普遍表达的基因。我们不能产生足够好的文库来代表青鳉种系EST。然而，在我们测序的上千条EST中，发现了几条感兴趣的EST，通过对这些EST的表达和功能分析，我们成功地从受精卵中追踪到了生殖系。青鳉的胚系在原肠胚形成阶段就已被发现，这表明其胚系的发育与哺乳动物中所见的相似。我们的研究结果表明，生殖细胞的发展更可能是其他脊椎动物的生殖细胞可以标记特定的细胞结构。此外，我们证明了生殖细胞经历了三个步骤的发展过程中，三种不同的模式迁移到性腺区。

medaka embryos are transparent, which allows us to monitor the development process occuring in morphogenesis in vivo. We have developed transgenic medaka using the regulatory regions of germline-specific expressed gene, vasa, fused with the green fluorescent gene. With this transgenics, we can observe the development of germline, the cell lineage for the future eggs or sperms. We have established the skills for isolating several germ cells and generated cDNA libraries for ESTs expressed exclusively in germline.Our initial purpose was to compare the medaka ESTs with mouse germline ESTs to reveal the genes commonly expressed beyond the species. We could not generate the libraries good enough for representing medaka germline ESTs. However, among the thousnads of ESTs we sequenced, several interesting ESTs have been found. By the expression and functional analyses of the ESTs, we successfully kept track of germline from fertilized eggs. Medaka germline is detected at the gastrulation stage, which has been suggesting that development of germline is similar to that seen in mammals. Our results indicate that germline development is more likely to that of other vertebrates where germline can be marked by specific cellular structures. Furthermore we demonstrated thatgermline goes through three steps of developmental process with three different modes of migration towards gonadal area.