中文摘要：

为研究华南虎狮弓蛔虫（Toxascaris leonina）线粒体基因的分子特性,对来源于4只华南虎的狮弓蛔虫的pcox1、pnad1和pnad4三种线粒体基因进行了扩增、克隆和测序,采用DNAStar和MEGA5.05软件对所获序列,以及Gen Bank中公布的狮弓蛔虫等相关序列进行了同源性比对和遗传进化分析。结果显示,4只华南虎的狮弓蛔虫扩增的pcox1、pnad1、pnad4基因序列长度分别为393、366、399 bp,3段基因序列种内变异明显低于种间变异。系统进化树中,狮弓蛔虫可分为猫科和犬科动物两大分支,其中4只华南虎的狮弓蛔虫与已报道的孟加拉虎、东北虎、华南虎、非洲狮、猞猁的狮弓蛔虫聚为一支;另外狼和犬的狮弓蛔虫聚为一支;以pnad1、pnad4建立的系统发育树中,虎源狮弓蛔虫又单独聚为一支,表明狮弓蛔虫在不同虎类之间并没有严格的宿主特异性。该研究为狮弓蛔虫的分子鉴定和分子遗传学研究提供了科学依据。

英文摘要：

In order to study the molecular characteristics of mitochondrial gene of Toxascaris leonina from South China tigers,three mitochondrial genes,pcox1,pnad1 and pnadi were amplified,cloned and sequenced.The sequence similarities and genetic evolutional relationship among T.leonina strains were analyzed by the DNAStar and MEGA version 5.05 software.The results showed that the sequence lengths of pcox1,pnad1 andpnadi genes of four samples were 393 bp,366 bp and 399 bp,respectively,and their intra-specific differences were significantly lower than inter-specific differences.The phylogenetic trees based on the three genes demonstrated that the T.leonina were divided into two groups,one comprising isolates from feline,the other comprising those from canine.In phylogenetic trees based onpnadl and pnad4,all the T.leonina isolates from tigers located in same small clade.These results indicated that there might be no host specificity between T.leonina from different tigers.The present study highlighted the research of molecular identification and genetic characterization of T.leonina.