荒川库蠓rDNA ITS2的序列测定与分析

库蠓种类繁多,给人畜健康带来巨大危害.荒川库蠓(Culicoides arakawae)是卡氏住白虫的重要传播媒介,引起鸡的卡氏住白虫病,导致蛋鸡产蛋量下降、肉鸡体重下降甚至死亡(Li et al.,2000),给养鸡业带来巨大经济损失.如何对各种媒介库蠓进行正确的区分或鉴定,是摆在各位寄生虫学家面前的具体问题.目前,寄生虫的分类鉴别主要依据形态学特征,一旦遇到形态学相似的近缘种就非常棘手.

Sequencing and analysis of ITS2 rDNA sequences of the midge (Culicoides arakawae)

The second internal transcribed spacer (ITS2) of Culicoides arakawae was amp lified by PCR, cloned and sequenced. wDNAsis software was used to analyze the IT S2 sequences of C. arakawae , two other Culicoides species and three othe r species of mosquitos which were obtained from GenBank. The lengths of the ITS2 region of the three Culicoides species (C.arakawae, C.variipennis and C.imico la) ranged from 205 to 250 bp, while the ITS2 region of Aedes albopictus a nd Anopheles albimanus were 424 bp and 435 bp respectively. The G+C content of C.arakawae was the lowest (20 87%) among the species examined, while tha t of Aedes albopictus (56 35%) and Anopheles albimanus (56 13%) were t he highest. The composition of the ITS2 sequence was highly variable, and there we re no conserved regions with more than two bases in their sequences. The conserv ed loci appeared at positions 9, 113, 117, 134, 141, 164, 197, 212, 292 and 396 loci. After the ITS2 sequences of the three species of Culicoides were align ed, four conserved regions were observed. The highest genetic similarity existed bet ween C.arakawae and C.imicola (40 9%) and the least between C.arakawa e, Aedes albopictus and Anopheles albimanus (7 7%). Since the ITS2 provid es enough genetic markers it could be used as a target region to set up diagnost ic PCR assay for Culicoides .