Tuesday, 16 November 2004

Genetic variability of horn fly populations in South America: PCR-RFLP analysis of the mitochondrial DNA

Aline Coelho da Rosa, alinecr@unicamp.br, Mariana Lucio Lyra, marilyra@unicamp.br, Ana Maria Lima de Azeredo-Espin, azeredo@unicamp.br, and Ana Cláudia Lessinger, lessinge@unicamp.br. Universidade Estadual de Campinas, Laboratório de Genética Animal, CBMEG, Campinas, São Paulo, Brazil

The animal mithocondrial genome has been widely used as an efficient molecular marker for population genetic studies in a wide range of insect species. In this work we analyze three specific regions of the horn fly, Haematobia irritans, mtDNA using PCR-RFLP:  Amplicon 1 (2100bp-2700bp), containing the control region; Amplicon 2 (1700bp), containing the genes COXIII, ATPase-6 and ATPase-8; and Amplicon 3 (650bp), containing the tRNAs cluster between NADH5 and NADH3 genes. Preliminary analysis of Amplicon 1 for samples from Argentina, Uruguay, Venezuela and Brazil allowed the detection of size polymorphism (about 600bp) in samples from Venezuela and Brazil, however no polymorphic PCR-RFLP patterns were found. The occurrence of ins-del events in the control region may be responsible for the observed size variation reported in this work. Analysis of Amplicon 2 indicates monomorphic restriction patterns for DraI, EcoRV, PvuII, XbaI and XhoI. Sequencing of Amplicon 3 is being conducted for structural analysis and identification of restriction sites for further PCR-RFLP analysis. The identification of length polymorphism for Amplicon 1 was an uncommon feature which may provide a potential marker for population genetic studies. Increasing numbers of individuals from these populations and additional populations from other geographic regions are being analyzed for a better characterization of H. irritans genetic variability. These results may contribute to understanding horn fly introduction and spread through South America. Financial Support: CNPq/PROFIX and FAPESP.

Species 1: Diptera Muscidae Haematobia irritans (horn fly)
Species 2: Diptera Muscidae Stomoxys calcitrans (stable fly)
Keywords: molecular markers, mtDNA

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