ABSTRACT
Triatoma brasiliensis is the most important vector of Chagas disease in the semiarid zone of the Northeast of Brazil. Several authors have reported the occurrence of four chromatic patterns with morphological, ecological, and genetic differences. In order to determine the existence of cytogenetic differentiation between these chromatic forms, we analyzed their karyotypes and the chromosome behavior during the male meiotic process. Triatoma brasiliensis shows distinct and specific chromosome characteristics, which differ from those observed in all other triatomine species. However, no cytogenetic differences were observed between the four chromatic forms of T. brasiliensis. The lack of chromosome differentiation among them could indicate that the populations of this species are in a process of differentiation that does not involve their chromosomal organization.
Subject(s)
Chromosomes/genetics , Cytogenetic Analysis , Insect Vectors/genetics , Triatoma/genetics , Animals , Genetic Variation , Karyotyping , Male , Meiosis , Phenotype , Sex Chromosomes/geneticsABSTRACT
Three species of triatomine bugs, Triatoma sordida, T. guasayana, and T. patagonica, were examined by cytogenetic (C-banded karyotypes and male meiotic process) and isoenzymatic studies. These three species, with different importance as Chagas' disease vectors, were found to be closely related according to their known ethologic, ecologic, and morphologic traits. Although they have the same diploid chromosome number (2n = 22 constituted by 20 autosomes and an XY male/XX female sex mechanism), each species has a distinct chromosomal behavior during male meiosis and a specific amount and localization of C-heterochromatic blocks. Moreover, these chromosome characteristics allowed us to differentiate two T. sordida populations. Isoenzymatic data confirmed the taxonomic status of the three species and together with our cytogenetic results questioned the species homogeneity of T. sordida.
Subject(s)
Chromosomes/genetics , Triatoma/genetics , Animals , Argentina/epidemiology , Brazil/epidemiology , Chagas Disease/epidemiology , Chromosomes/metabolism , Classification , Female , Genome , Heterochromatin/metabolism , Insect Control , Isoenzymes/analysis , Karyotyping , Male , Meiosis/genetics , Triatoma/classification , Triatoma/enzymologyABSTRACT
The chromosome numbers of 46 out of the 122 currently recognized species of Triatominae (Hemiptera, Reduviidae) are summarized. We present the number of autosomes, the sex mechanism and the first reference for each karyotype.
