Abstract
We analyzed the main karyologic changes that have occurred during the dispersion of Triatoma infestans, the main vector of Chagas disease. We identified two allopatric groups, named Andean and non-Andean. The Andean specimens present C-heterochromatic blocks in most of their 22 chromosomes, whereas non-Andean specimens have only 4–7 autosomes with C-banding. These heterochromatin differences are the likely cause of a striking DNA content variation (approximately 30%) between Andean and non-Andean insects. Our study, together with previous historical and genetic data, suggests that T. infestans was originally a sylvatic species, with large quantities of DNA and heterochromatin, inhabiting the Andean region of Bolivia. However, the spread of domestic T. infestans throughout the non-Andean regions only involved insects with an important reduction of heterochromatin and DNA amounts. We propose that heterochromatin and DNA variation mainly reflected adaptive genomic changes that contribute to the ability of T. infestans to survive, reproduce, and disperse in different environments.
Highlights
We analyzed the main karyologic changes that have occurred during the dispersal of Triatoma infestans, the main vector of Chagas disease
American trypanosomiasis or Chagas disease is well recognized as the most serious human parasitic disease of the Americas in terms of its social and economic impact (1). This disease is caused by the flagellate protozoan Trypanosoma cruzi, and it is transmitted by bloodsucking insects of the subfamily Triatominae (Hemiptera, Reduviidae)
The number of C-banded autosomes, 2) the C-banding on the X sex chromosome, and 3) the DNA content (Figures 2 and 3, Tables 1 and 2)
Summary
We analyzed the main karyologic changes that have occurred during the dispersal of Triatoma infestans, the main vector of Chagas disease. The Andean specimens present C-heterochromatic blocks in most of their 22 chromosomes, whereas non-Andean specimens have only 4–7 autosomes with C-banding These heterochromatin differences are the likely cause of a striking DNA content variation (approximately 30%) between Andean and non-Andean insects. Studies on the changes that have taken place in such domestication and Triatoma infestans represents the best example of spreading and adaptation to domicilies observed in a triatomine species This species is the main and widespread vector in South America, responsible for about half of the 12 million cases of Chagas disease reported worldwide. T. infestans is found almost exclusively in domestic and peridomestic environments, occupying cracks and crevices in rural dwellings and domestic animal enclosures The presence of this species in sylvatic habitats (rock piles in association with wild guinea pigs) has only been confirmed in the Andean valleys of Cochabamba and Sucre in Bolivia (3–5). Student t test was used for statistical analysis of the results obtained by C-banding and flow cytometry; p < 0.001 was considered significant
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