Harada Yoshito, Takagaki Yuhei, Sunagawa Masahiko, Saito Takako, Yamada Lixy, Taniguchi Hisaaki, Shoguchi Eiichi, Sawada Hitoshi
Sugashima Marine Biological Laboratory, Graduate School of Science, Nagoya University, Sugashima, Toba 517-0004, Japan.
Science. 2008 Apr 25;320(5875):548-50. doi: 10.1126/science.1152488. Epub 2008 Mar 20.
Hermaphroditic organisms avoid inbreeding by a system of self-incompatibility (SI). A primitive chordate (ascidian) Ciona intestinalis is an example of such an organism, but the molecular mechanism underlying its SI system is not known. Here, we show that the SI system is governed by two gene loci that act cooperatively. Each locus contains a tightly linked pair of polycystin 1-related receptor (s-Themis) and fibrinogen-like ligand (v-Themis) genes, the latter of which is located in the first intron of s-Themis but transcribed in the opposite direction. These genes may encode male- and female-side self-recognition molecules. The SI system of C. intestinalis has a similar framework to that of flowering plants but utilizing different molecules.
雌雄同体生物通过一种自我不亲和（SI）系统避免近亲繁殖。原始脊索动物（海鞘）玻璃海鞘就是这样一种生物的例子，但其SI系统背后的分子机制尚不清楚。在这里，我们表明SI系统由两个协同作用的基因座控制。每个基因座都包含一对紧密连锁的多囊蛋白1相关受体（s-Themis）和纤维蛋白原样配体（v-Themis）基因，后者位于s-Themis的第一个内含子中，但转录方向相反。这些基因可能编码雄方和雌方的自我识别分子。玻璃海鞘的SI系统与开花植物的SI系统具有相似的框架，但使用的是不同的分子。
