Molecular mechanisms underlying self-sterility in the ascidians

点击翻译按钮获取中文摘要

Little is so far known on the molecular mechanisms underlying self-sterility in the ascidian gametes, a typical example of the allogeneic recognition. However, an allogeneic interaction named "contact reaction" is well established in the hemocytes of the ascidian, Halocynthia roretzi. On an assumption that allo-recognition molecules in gametes and those in hemocytes are the same or closely related, we searched for such molecules in the gametes and hemocytes of the ascidian. Major findings in this project are itemized as follows.1) Vacuolate cells secreted phenol oxidase upon contact reaction, which allowed us to develop a quantitative assay for the contact reaction.2) Vacuolated cells expressed an allo-molecule (s) and its receptor, whereas granular cells did not express such a molecule in a way to be recognized by vacuolated cells.3) Follicle cells attaching to the vitelline coat expressed an allo-molecule (s).4) cDNA of sperm alpha-L-fucosidase that mediates sperm binding to the vitelline coat was cloned and partially sequenced.5) A putative sperm-receptor glycoprotein of 70 kDa was isolated from the vitelline coat and partially sequenced.6) The gametes became self-fertile in high Mg^<2+>-or caffeine-seawater.