Analysis Of Cytochrome C Oxidase Ⅰ Gene Of Oncomelania Hupensis From Schistosomiasis Japonica Epidemic Area In Yunnan Province

【Objective】To study mitochondrial cytochrome C oxidase I(COI)gene diversity of Oncomelania hupensis and construct phylogenetic trees;To study the genetic diversities of O.h.robertsoni,and discuss whether COI gene suit to the systematic study of Oncomelanoia hupensis,so that provide evidence for prevention and cure of schistosomiasis japonica, especially molluscicide in Yunnan province.【Methods】The snails are collected from schistosomiasis japonica epidemic area in Yununan province.Genomic DNA is extracted from the snail.Mitochondrial cytochrome oxidase I(COI) gene fragments of the snails are amplified by PCR(polymerase chain reaction)method and then sequenced.The sequences of the PCR products compared homogenously with COI gene are downloaded from Genbank homology by DNAstar software.The same gene of Biomphalaria glabrata(AY380531)and O.h.minima(DQ212795)from Genbank as outgroup,they were assembled and edited by using ClustalX1.83 software.The phylogenetic trees are constructed by using Neighbor-Joining(NJ),Unweighted pair group method with arthmetid mean(UPGMA), Maximum Parsimony(MP)and Maximum Likelihood(ML)methods through MEGA4.0, PAUP~*4.0 and PHYML softwares.Genetic distances are computed by using program MEGA4.0.【Results】The consequence of the COI genes amplified of Oncomelania hupensis are about 638bp.For O.h.robertsoni,the conserved sites are 533,the variable sites are 105,the parsimony informatic sites are 91,the singleton sites are 14.The average content of A,T,C and G to COI genes of O.h.robertsoni is 23.0%,37.6%,18.3%,21.1%,respectively.A+T content is 60.6%, while G+C content is 39.4%,which shows a strong A+T bias.Ratio of transition to transversion(R)of COI gene sequence is 6.2 to O.h.robertsoni.The saturation analysis shows that TS,TV and uncorrected p-distance have good linear relation,its substitution is not saturated. The uncorrected p-distance between O.h.robertsoni and all other Oncomelania hupensis are 0.1197-0.1313(0.1255±0.0058),The distance by Kimura 2-parameter is 0.1485-0.1343 (0.1414±0.0071);The uncorrected p-distance within all other Oncomelania hupensis is 0.0091-0.0252(0.01715±0.00805),The distance by Kimura 2-parameter is 0.0093-0.0258(0.01755±0.00285).The uncorrected p-distance between Yunnan branch and Sichuan branch is 0.0857,The distance by Kimura 2-parameter is 0.0928.The phylogenetic trees by three motheds have a same topology.The phylogenetic trees have two populations,one is Yunnan branch,Another is Sichuan branch.【Conclusions】①Both Yunnan branch and Sichuan branch has genetic variation.②It indicates that COI gene do not adapt to the study of the subspecies systematics of Oncomelanoia hupensis, but COI gene support the two stable branches of O.h.robertsoni.③O.h.robertsoni are divided into two independent populatios:one is Yunnan branch and another is Sichuan branch.