Phylogenetic aspects of the cyclostomes with special attention to the primitive complement sysytem.

盲鳗是现存最原始的脊椎动物，被认为仅靠先天免疫系统来防御病原体。为了了解先天免疫系统的进化，我们从盲鳗的血清中分离出补体C3。在本研究中，我们利用基于几种丝氨酸蛋白酶之间的保守氨基酸延伸设计的退行性引物，采用RT-PCR方法鉴定盲鳗C3转化酶。从盲鳗肝脏cDNA文库中分离得到一个全长cDNA克隆，利用其中一个克隆的RT-PCR产物作为探针进行分析，发现该cDNA编码盲鳗甘露糖结合凝集素相关丝氨酸蛋白酶WASP)1。这一证据有力地表明盲鳗至少通过由凝集素途径组成的补体系统来防御病原体

Hagfish is the most, primitive extant vertebrate and thought to defend itself against pathogens only by innate immune system. With a view to understanding the evolution of the innate immune system, we have isolated complement C3 from the serum of hagfish. In this study, our attempt to identify a hagfish C3 convertase was carried out by RT-PCR using degenerative primers designed on the basis of the conserved amino acid stretches among the several kinds of serine proteases. Analyses of a full-length cDNA clone isolated from a hagfish liver cDNA library using one of the cloned RT-PCR products as a probe indicated that this cDNA encoded hagfish mannose-binding lectin-associated serine protease WASP)1. This evidence strongly suggests that the hagfish defends itself against pathogens at least by the complement system composed of lectin pathway