Phylogenic Study Of Oncomelania Hupensis Isolates From Guangxi,Yunnan And Hunan Province

OBJECTIVE: To analyze the genetic difference of Oncomelania hupensisfrom three province of China (Guangxi, Yunnan and Hunan)and explore theorigin of Oncomelania hupensis in Guangxi.METHODS: The snails were collected from Jingxi county in Guangxi,Eryuan county in Yunnan and Yueyang city in Hunan,where schistosomasis isendemic. The fragments of mitochondrial cytochrome C oxidase I(COâ… ) andcytochrome b(cytb) genes were obtained by PCR from the snail genomic DNA.The sequences of the PCR products were analyzed by Pairwise Blast Softwarecomparing with the same gene of Biomphalaria glabrata(NC₀05439) fromGenebank. Sequences of each geographic isolate were assembled and edited byusing Clustal W(1.82) software. The distance matrix was estimated by the Kimuradouble parameter method. The phylogenic tree was constructed in PHYLIP(2000)and MEGA(2.1) software using both unweighted pair group method witharthmetid mean and aximum parsimony methods. The sequences of COâ… gene ofthe three isolates were compared with that of other isolates published in theGenebank. At the same time the data of breeding environments, paleogeographyand geographic distribution of Oncomelania hupensis in three provinces werecollected and analyzed.RESULTS: When considering in COâ… gene the homogeneity and thedistance matrix between Jingxi isolate and the Yueyang isolate is 94% and 0.051while in Cytb gene the homogeneity and the distance matrix is 97% and 0.031,respectively. The same items between Jingxi and Eryuan isolates are 86%, 0.158,76% and 0.405, respectively. And that between Yueyang and Eryuan isolates are87%, 0.158, 77% and 0.391, respectively. The sequence homogeneities among thethree isolates and phylogenic trees based on COâ… and Cytb genes are coincidence.In the phylogenic trees, Jingxi and Yueyang isolate belong to one branch whileEryuan isolate is on the other branch apart from them. When compared the COâ… gene of the three isolates with that of other geographic isolates published inGenebank, the homogeneities among Jingxi, Yueyang and Hanyang(Hubei)are93%～94% and the distance matrix in the phylogenic tree are 0.044～0.053. Thatamong Jingxi , Eryuan , Dali (Yunan )and Mianzhu (Sichuan) are 85%～86% and0.148～0.151,respectively.The homogeneities among Yueyang, Eryuan and Daliare 84%～87% and the distance matrix are 0.153～0.155 and that among Eryuan,Dali and Mianzhu are 94%～96% and 0.002 to 0.058,respectively. The phylogentictree shows that isolates of Jingxi ,Yueyang and Hanyang belong to one branchand isolates of Eryuan, Dali and Mianzhu belong to other branch.CONCLUSION: According to the sequences of COâ… and Cytb genes, thefiliations of three geographic isolates of Oncomelania hupensis was estimated asfollows: Jingxi isolate and Yueyang isolate may develop from one nearer originbecause they have high homogeneity in sequences and belong to one branch in thephylogenic trees while Eryuan isolate is more far away in the kinship.