Holocentric chromosome evolution in kissing bugs (Hemiptera: Reduviidae: Triatominae): diversification of repeated sequences

Abstract

BackgroundThe analysis of the chromosomal and genome evolution in organisms with holocentric chromosomes is restricted by the lack of primary constriction or centromere. An interesting group is the hemipteran subfamily Triatominae, vectors of Chagas disease, which affects around 6 to 7 million people worldwide. This group exhibits extensive variability in the number and chromosomal location of repeated sequences such as heterochromatin and ribosomal genes. This paper tries to reveal the significant differences of the repeated sequences among Triatoma species through the use of genomic DNA probes.MethodsWe analysed the chromosomal distribution and evolution of repeated sequences in Triatoma species by genomic in situ hybridization (GISH) using genomic DNA probes from two North American Triatoma species. These genomic probes were hybridized both on their own chromosomes and on other Triatoma species from North and South America, with different amounts and chromosome location of C-heterochromatin. The results were compared with those previously described using South American Triatoma genomic probes.ResultsWe observed two chromosomal hybridization patterns: (i) very intense hybridization signals concentrated on specific chromosomal regions or particular chromosomes; and (ii) lower intensity hybridization signals dispersed along all chromosomes. Self-GISH on T. rubrofasciata and T. dimidiata chromosomes presented strong hybridization signals on all C-heterochromatin regions. However, when we perform genomic cross-hybridizations, only strong signals are detected on the Y chromosome, leaving the C-heterochromatic autosomal regions unmarked.ConclusionsWe confirm that repeated DNA of the Y chromosome is shared among Triatoma species and probably represents an ancestral character of the Triatomini tribe. On the contrary, autosomal heterochromatic regions are constituted by species-specific DNA repeats, most probably satDNA families, suggesting that Triatoma speciation involved the amplification of diverse types of autosomal repeats. Molecular characterization of principal repetitive DNAs seems to be an appropriate approach to infer evolutionary relationships in triatomines.

Satellitome Analysis of Rhodnius prolixus, One of the Main Chagas Disease Vector Species

“…No new shared satDNA families have been detected between the two species other than the four previously described. The existence of only four low copy-number satDNA families of R. prolixus shared with T. infestans is in accordance with genomic in situ hybridization analyses in R. prolixus using Triatoma genomic probes, which revealed that repetitive DNA between both genera were not shared at a great scale [ 40 , 41 ]. These results reinforce the idea of the great genomic difference between both Triatominae genera.…”

“…In consequence, other repetitive DNAs with short repeat units may have been omitted in this analysis. Therefore, (GATA) n repeats amount was calculated since this repeat is extremely abundant in the T. infestans genome and it seems to be the only repeat DNA shared in the Y chromosomes in Triatoma species [ 41 ]. In R. prolixus , (GATA) n repeats are barely 0.001% of the genome, far away from the 4.5% in T. Infestans [ 13 ].…”

Comparative Analysis of Repetitive DNA between the Main Vectors of Chagas Disease: Triatoma infestans and Rhodnius prolixus

“…At least two satDNAs are present on the T. infestans Y chromosome, TinfSat01-33 and (GATA) n , but only (GATA) n repeats are common to all Triatomini species [ 15 ]. The Y chromosome sequence conservation in species-rich insect groups is uncommon, so, its conservation in the Triatomini tribe probably represents an ancestral character in this group, as previously suggested by GISH analyses [ 28 , 29 ]. In Rhodniini, the heterochromatic Y chromosome is constituted by other types of DNA sequences that are not revealed by GISH (using Triatoma species probes) or fluorescence-banding analyses [ 27 , 28 ].…”

“…In Triatomini, the Y chromosome is mainly composed by A+T rich repeated DNA sequences [ 20 , 27 ]. Genomic in situ hybridization (GISH) analyses on fifteen Triatomini species from four different genera revealed that these repetitive sequences were highly conserved [ 28 , 29 ]. At least two satDNAs are present on the T. infestans Y chromosome, TinfSat01-33 and (GATA) n , but only (GATA) n repeats are common to all Triatomini species [ 15 ].…”

Números cromosómicos, análisis citogenéticos y primeras descripciones de los cariotipos de Doru lineare y D. luteipes (Dermaptera, Forficulidae, Insecta)

“…Los cromosomas holocinéticos fueron mencionados por primera vez por Hughes-Schrader y Ris (1941) en coccidos (Hemiptera; Homóptera). Investigaciones posteriores revelaron que otros insectos tenían como característica este tipo de cromosomas, entre ellos los órdenes Odonata, Dermaptera, Zoraptera, Phthiraptera, Psocoptera, Lepidoptera, Tricoptera y Hemiptera (Mola, 1995, Golub y Nokkala, 2004Kuznetsova, Grozeva, Nokkala, 2004;Gavrilov, 2007;Papeschi y Bressa, 2006;Thakur y Gautam, 2013;Pita et al, 2017). Dentro de los arácnidos se encuentran representados en el grupo de los escorpiones en la familia Buthidae, en las arañas en el orden Aranae en la superfamilia Dysderidae y orden Astigmata (ácaros) (Rodríguez Gil, Mola, Papeschi, Scioscia, 2002;Schneider, Zacaro, Pinto-Da-Rocha, Candido, Cella, 2009).…”