Study On MtDNA-ND4 And MtDNA-COI Gene Polymorphism Of Aedes Albopictus, Vector Mosquitoes Of Dengue

Aim To study the characteristics of mitochondrial DNA cytochrome oxidase sunbunit I (mtDNA-COI) and NADH dehydrogenase sunbunit 4(mtDNA-ND4) gene, explore to distinguish Strains of Aedes albopictus on the level of DNA molecular, observe the population genetic structure and the gene flow of Aedes albopictus, understand and propose genetic polymorphism of vectors and its relation to epidemic of dengue, evaluate the value of mtDNA-COI and mtDNA-ND4 as genetic marker in distinguishing strains of Aedes albopictus on the level of DNA molecular. Method Collect the mosquito from dengue epidemical and non-endemic areas at different altitude levels, was fed into adult. Together with Aedes albopictus from other regions (Yunnan, Shanghai, Guizhou )in China, its mtDNA-ND4 and mtDNA-COI were amplified and the gene sequences were sequenced and analyzed. Result 1.The ND4 fragment contained 324 nucleotides, with 17 polymorphic sites. The A+T content of ND4 gene is 73.2%. The frequency of transversion is 62.5%.The COI fragment contained 415 nucleotides, with 8 polymorphic sites. The A+T content of COI gene is 70.2%. The frequency of transversion is 64.71%. The nucleotide diversity(pi) of ND4 gene was 0.012, higher than COI gene which was 0.00277. 2.In this study, 5 haplotypes were obtained from 19 specimens among 4 geographic populations from Fujian province based on the ND4 gene. The haplotype diversity is 0.442. Phylogenetic trees of haplotypes constructed with N-J method showed that genetic difference existed among 4 populations from Fujian province. Genealogical relationship showed that the whole haplotypes were evolved from two of them separately. Molecular phylogenetic trees were constructed with N-J and UPGMA method. 3. Genetic analysis of 41 specimens of 4 populations from Fujian, Yunnan, Shanghai, Guizhou province was conducted based on the COI gene fragment. 6 haplotypes were obtained, including 4 haplotypes from 16 specimens from Fujian. The molecular diversity indices showed that Fujian population was higher than other geographic population. Genealogical relationship and minimum spanning trees indicate the evolutionary relationship among haplotypes and the existence of one well defined clade with 3 undiscovered haplotypes. Analysis of molecular variance (AMOVA) showed that the genetic difference mainly came from variation within population whose the percentage was 71.86% and the degree of that was lower(FST=0.28136). Molecular phylogenetic trees were constructed with N-J and UPGMA method. Conclusion In this study, the COI gene fragment was demonstrated to be more useful in identifying Aedes albopictus within populations than the ND4. All results showed that genetic difference existed among population of strains, but the degree was lower. This difference mainly came from variation within population and might cased by genetic drift. It must be pay the great attention that Dongshan in Fujian province bordered on epidemical area, was at risk of outbreak of dengue, where the density of Ae. larval and level of mitochondrial gene polymorphism were higher.