Anopheles stephensi is the main vector of urban malaria in South Asia. Three ecological variants （‘type’, ‘mysorensis’ and ‘intermediate’） of An. stephensi have been reported on the basis of ecology and egg mo...Anopheles stephensi is the main vector of urban malaria in South Asia. Three ecological variants （‘type’, ‘mysorensis’ and ‘intermediate’） of An. stephensi have been reported on the basis of ecology and egg morphology. However, it is unclear if there is any genetic isolation between the three variants. We analyzed the three variants of An. stephensi using eight microsatellite loci and found that large and significant genetic differentiation exists between them （mean FST = 0.393 and mean RST = 0.422）. Pairwise estimates of genetic differentiation between the variants were ‘type’ versus ‘mysorensis’ （mean FsT = 0.411 and mean RST = 0.308）, ‘type’ versus‘intermediate’ （mean FsT = 0.388 and mean RST = 0.518） and ‘intermediate’versus ＇mysorensis＇ （mean FST = 0.387 and mean RST = 0.398） and all were statistically significant （P 〈 0.05）. The greater sensitivity of RST in differentiation indicated that mutations and not genetic drift had generated the differences between three variants of An. stephensi. The present study indicated large genetic differentiation and presence of non-significant low level ofgene flow between the three variants （‘type’,‘ mysorensis’ and ‘intermediate’） of An. stephensi.展开更多
Objective:To identify the biological forms,sporozoite rate and molecular characterization of the Anopheles stephensi(An.stephensi)in Hormozgan and Sistan-Baluchistan provinces,the most important malarious areas in Ira...Objective:To identify the biological forms,sporozoite rate and molecular characterization of the Anopheles stephensi(An.stephensi)in Hormozgan and Sistan-Baluchistan provinces,the most important malarious areas in Iran.Methods:Wild live An.stephensi samples were collected from different malarious areas in southern Iran.The biological forms were identified based on number of egg-ridges.Molecular characterization of biological forms was verified by analysis of the mitochondrial cytochrome oxidase subunit I and II(mtDNA-COI/COII).The Plasmodium infection was examined in the wild female specimens by species-specific nested-PCR method.Results:Results showed that all three biological forms including mysorensis,intermediate and type are present in the study areas.Molecular investigations revealed no genetic variation between mtDNA COI/COII sequences of the biological forms and no Plasmodium parasites was detected in the collected mosquito samples.Conclusions:Presence of three biological forms with identical sequences showed that the known biological forms belong to a single taxon and the various vectorial capacities reported for these forms are more likely corresponded to other epidemiological factors than to the morphotype of the populations.Lack of malaria parasite infection in An,stephensi,the most important vector of malaria,may be partly due to the success and achievement of ongoing active malaria control program in the region.展开更多
文摘Anopheles stephensi is the main vector of urban malaria in South Asia. Three ecological variants （‘type’, ‘mysorensis’ and ‘intermediate’） of An. stephensi have been reported on the basis of ecology and egg morphology. However, it is unclear if there is any genetic isolation between the three variants. We analyzed the three variants of An. stephensi using eight microsatellite loci and found that large and significant genetic differentiation exists between them （mean FST = 0.393 and mean RST = 0.422）. Pairwise estimates of genetic differentiation between the variants were ‘type’ versus ‘mysorensis’ （mean FsT = 0.411 and mean RST = 0.308）, ‘type’ versus‘intermediate’ （mean FsT = 0.388 and mean RST = 0.518） and ‘intermediate’versus ＇mysorensis＇ （mean FST = 0.387 and mean RST = 0.398） and all were statistically significant （P 〈 0.05）. The greater sensitivity of RST in differentiation indicated that mutations and not genetic drift had generated the differences between three variants of An. stephensi. The present study indicated large genetic differentiation and presence of non-significant low level ofgene flow between the three variants （‘type’,‘ mysorensis’ and ‘intermediate’） of An. stephensi.
基金financially supported by Tehran University of Medical Sciences(TUMS)(Grant No.89-01-27-10448)
文摘Objective:To identify the biological forms,sporozoite rate and molecular characterization of the Anopheles stephensi(An.stephensi)in Hormozgan and Sistan-Baluchistan provinces,the most important malarious areas in Iran.Methods:Wild live An.stephensi samples were collected from different malarious areas in southern Iran.The biological forms were identified based on number of egg-ridges.Molecular characterization of biological forms was verified by analysis of the mitochondrial cytochrome oxidase subunit I and II(mtDNA-COI/COII).The Plasmodium infection was examined in the wild female specimens by species-specific nested-PCR method.Results:Results showed that all three biological forms including mysorensis,intermediate and type are present in the study areas.Molecular investigations revealed no genetic variation between mtDNA COI/COII sequences of the biological forms and no Plasmodium parasites was detected in the collected mosquito samples.Conclusions:Presence of three biological forms with identical sequences showed that the known biological forms belong to a single taxon and the various vectorial capacities reported for these forms are more likely corresponded to other epidemiological factors than to the morphotype of the populations.Lack of malaria parasite infection in An,stephensi,the most important vector of malaria,may be partly due to the success and achievement of ongoing active malaria control program in the region.
