Abstract
The subfamily Triatominae (Hemiptera, Reduviidae) includes 150 species of blood-sucking insects, vectors of Chagas disease or American trypanosomiasis. Karyotypic information reveals a striking stability in the number of autosomes. However, this group shows substantial variability in genome size, the amount and distribution of C-heterochromatin, and the chromosome positions of 45S rDNA clusters. Here, we analysed the karyotypes of 41 species from six different genera with C-fluorescence banding in order to evaluate the base-pair richness of heterochromatic regions. Our results show a high heterogeneity in the fluorescent staining of the heterochromatin in both autosomes and sex chromosomes, never reported before within an insect subfamily with holocentric chromosomes. This technique allows a clear discrimination of the heterochromatic regions classified as similar by C-banding, constituting a new chromosome marker with taxonomic and evolutionary significance. The diverse fluorescent patterns are likely due to the amplification of different repeated sequences, reflecting an unusual dynamic rearrangement in the genomes of this subfamily. Further, we discuss the evolution of these repeated sequences in both autosomes and sex chromosomes in species of Triatominae.
Highlights
Heterochromatin variation in triatomines includes remarkable changes in the amount, size, chromosome location and behaviour of C-blocks during cell divisions (Panzera et al 2010)
The aim of the present study was to compare the karyotypes of 41 species from six different genera according to the occurrence and distribution of DAPI/chromomycin A3 (CMA) bands, thereby allowing a better characterisation of heterochromatic regions in terms of their relative enrichment with A+T or G+C base pairs, respectively
Chromosome preparations for C-CMA/DAPI banding were made from males and females of 41 triatomine species from the two principal tribes of the subfamily, Rhodniini and Triatomini, which include more than 90% of the 150 recognised species
Summary
Heterochromatin variation in triatomines includes remarkable changes in the amount, size, chromosome location and behaviour of C-blocks during cell divisions (Panzera et al 2010). The aim of the present study was to compare the karyotypes of 41 species from six different genera according to the occurrence and distribution of DAPI/CMA bands, thereby allowing a better characterisation of heterochromatic regions in terms of their relative enrichment with A+T or G+C base pairs, respectively. With this strategy, we can suggest a broad overview of the evolution of these repeated sequences both in autosomes and in sex chromosomes in the subfamily Triatominae
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