Analysis of species specificity in endoparasitoids

幼虫内寄生蜂必须在生理条件下调节寄主，以获得卵和幼虫发育所需的适宜状态。在能够寄生同一寄主种类的两种不同寄生蜂之间，一种寄生小蜂被限制寄生在寄主幼虫的体育场，而另一种寄生小蜂kariyai能够成功地寄生在整个体育场。根据多聚核糖核酸病毒的特性，各寄生蜂的毒液相互交换产生寄主调节。每个基因组DNA片段与PDV的正反向基因组DNA片段杂交。此外，我们还报道了在寄主分离的拟青霉睾丸中表达的Cotesia kariyai Polydna Virus(CkPV)基因的克隆和鉴定。我们从宿主睾丸的cDNA文库中分离到编码CkPV mRNAs的克隆。我们在宿主睾丸表达的一个CkPV基因中发现了RNaseT2家族的两个基序。CkPV RNase T_2片段与多个病毒基因组片段杂交。以克隆的CkPV RNase T_2基因为探针进行Northern印迹分析表明，寄生后4-12h分别检测到3.1kbP和2.3kbpmRNAs，这是在寄主睾丸出现染色质异常的细胞出现之前。

Larval endoparasitoids have to regulate the host in the physiological condition to acquire the suitable state for the development of their eggs and larvae. Between two different parasitoids being able to attack the same host species (Pseudaletia separata), one parasitoid, Cotesia ruficrus is restricted to parasitize the young stadium of the host, while another parasitoid, Cotesia kariyai is able to parasitize successfully through all stadium. Reciprocal exchanging of the polydnavirus and the venom of each parasitoid produced the host regulation according to the characteristics of the polydnavirus. Each genomic DNA segments hybridized with the reciprocal genornic DNA segments of PDV.Furthermore, we reported the cloning and characterization of Cotesia kariyai polydnavirus (CkPV) genes expressed in host Pseudaletia separata testes. We isolated clones encoding CkPV mRNAs from a cDNA library of host testes. We found two motif sequences of the RNase T_2 family in one of CkPV gene expressed in host testes. The CkPV RNase T_2 fragment was hybridized to more than one viral genome segments. By northern blot analysis using cloned CkPV RNase T_2 gene as a probe, we showed the 3.1 kbp and 2.3 kbp mRNAs were detected 4-12h after parasitization, which Was before the appearance of cells with abnormal chromatin in the host testes.