21-P031 Insights into signalling mechanisms of Latrophilins

It is well known that activin-treated presumptive ectoderm, which is generally called as animal cap, in amphibian differentiates into various types of tissues and organs such as notochord, muscle, heart, and kidney. However, there has been no report that primordial germ cells are induced by activin treatment for animal caps. Anterior or posterior axial mesoderms can be, respectively, induced by middle-low or -high concentrations of activin treatments for dissociated animal cap cells. It is reported that sandwich of two different reaggregates from these dissociated animal cap cells has a potent activity of convergent extension. Using combination of this assay and microarray gene analyses, we tried to isolate new regulators of convergent extension phenomenon. As a result, novel candidate molecule was not isolated from this assay although only a few convergent extension markers were confirmed. Unexpectedly, most genes showing big differences of expression levels in this screening were primordial germ cell markers such as germs, Xpat, and DEADSouth RNA helicase. In addition to them, some novel or functionally unreported molecules were contained in the other high-scored genes of this screening. This is the first report that activin treatment for animal cap cells can induce primordial germ cells, suggesting that the sandwich assay that we used in this study is able to be a good strategy to isolate genes related to primordial germ cell formation.