Study On Genomic DNA Polymorphism In Anopheles Dirus And An.stephensi Of The Vectors Of Human Malaria

Objective To analyze the genomic DNA polymorphism in An.dirus and An.stephensi of different susceptible to Plasmdium yoelii, so as to explore host genotype by parasite genotype interactions underlying the susceptibility of anopheline mosquitoes to plasmodium.Methods The genomic DNA was extracted from the adults of An.dirus and An.stephensi. On the one hand, the genomic DNA for both species were amplified by RAPD, and then the amplified products were carried on agarose gel electrophoresis. The gel-purified RAPD bands which had similar mobility were isolated and sequenced. Sequence alignment was performed by using DNASIS program. On the other hand, the rDNA ITS2 region for both species were amplified by PCR and sequenced, and the amplified products were analyzed by restriction endonuclease digestion (RFLP). The correspondent sequence of An.dirus and An.stephensi were searched from GenBank. All these sequences were aligned and compared using Clustal W program, and the phylogenetic tree was constructed by MEGA program.Results The genomic DNA of An.dirus and An.stephensi were successfully amplified by RAPD, and there was obvious difference in their RAPD fingerprinting on genomic DNA, respectively. Sequence alignment of four pairs of RAPD bands which had similar mobility between different anopheline mosquitoes showed that each pair of RAPD bands were differed in GC content and Simple Sequence Repeat, and their difference were in the arrange from 60.0% to 61.9% in nucleotide sequences. It was demonstrated that there were polymorphism in the length and construction of RAPD bands which had similar mobility. Moreover, there are significantly different from the RFLP patterns of rDNA ITS2 in An.dirus and An.stephensi by restriction endonuclease Xho I, the length of ITS2 region was 715bp in An.dirus and 466bp in An.stephensi, Sequence alignment of ITS2 region in An.dirus and An.stephensi showed that ITS2 region were differed in GC content and Simple Sequence Repeat, and the difference was 53.5% in nucleotide sequences. It was also demonstrated that there were polymorphism in the length and construction of ITS2 region in An.dirus and An.stephensi. The phylogenetic tree obtained by MEGA program showed An.dirus and An.stephensi as a independent taxon to each other.Conclusions Our results have indicated that gene polymorphism is distinguished between An.dirus and An.stephensi, and the basis for compatibility between plasmodium yoelii and mosquito host appear to be, at least in part, determined by the different genetic background of An.dirus and An.stephensi. These findings are useful for the further studies on the interactions between anopheline mosquitoes host and plasmodium genotypes.