Cytogenetic characterization of Eurysternus caribaeus (Coleoptera: Scarabaeidae): evidence of sex-autosome fusion and diploid number reduction prior to species dispersion

Abstract

Mitotic and meiotic chromosomes of several populations of Eurysternus caribaeus (Coleoptera: Scarabaeidae) were analysed through conventional staining, C-banding, base-specific fluorochromes, silver nitrate staining and fluorescent in situ hybridization (FISH). All specimens showed 2n = 8 in their karyotypes, with a neo-XY sex system (Y is a submetacentric and X a metacentric) and three pairs of submetacentric autosomes. The analysis of constitutive heterochromatin (CH) revealed small blocks located in the centromeric region of all chromosomes which do not present positive staining under the fluorochromes CMA 3 and DAPI. Silver nitrate staining revealed that the nucleolar organizer region (NORs) is associated with the sex chromosomes. The FISH technique revealed that rDNA sites in the X and Y are different in size. Data from different populations indicate that the diploid number reduction (2n = 8) observed in E. caribaeus is established and presumably has preceded the dispersion of this species. Moreover, this reduction occasioned the translocation of rDNA sites to the sex chromosomes, X and Y, an uncommon pattern in Scarabaeidae that was observed for the first time by the FISH in this work.

Chromosome mapping of 28S ribosomal genes in 11 species of Cassidinae (Coleoptera: Chrysomelidae)

“…The species with interstitial and/or centromeric rDNA cistrons are mainly members of the families Scarabaeidae and Chrysomelidae (subfamily Alticinae). As recorded in the present study, the changes in the location of the sites of rDNA are described in species with similar karyotype characteristics (Virkki, 1983;Yadav et al, 1992;Bione et al, 2005;Almeida et al, 2006Almeida et al, , 2010Arcanjo et al, 2009Arcanjo et al, , 2013Silva et al, 2009;Cabral de Mello et al, 2010, 2011bOliveira et al, 2010Oliveira et al, , 2012b. The differences in the location of rDNA in closely related species with similar chromosomal characteristics may be a result of small chromosomal rearrangements, which change the position of the ribosomal site without modifying the metacentric chromosomal morphology.…”

Chromosome Analysis of 82 Species of Scarabaeoidea (Coleoptera), with Special Focus on NOR Localization

“…Thus, most of the recent literature is on rDNA gene localization by FISH. Besides our own data, we could find 11 publications reporting the analysis of 22 species of Scarabaeoidea: 3 Melolonthinae [Moura et al, 2003]; 10 Scarabaeinae [Bione et al, 2005b;Colomba et al, 2006;Arcanjo et al, 2009;Silva et al, 2009;Oliveira et al, 2010], 2 Geotrupidae [Vitturi et al, 1999;Colomba et al, 2004]; 3 Dynastinae [Vitturi et al, 2003;Bione et al, 2005a]; 3 Rutelinae [Bione et al, 2005b] and 1 Lucanidae [Colomba et al, 2000]. A single species (Dorcus parallelipipedus) of this series was also studied by us, with similar results [Colomba et al, 2000;Dutrillaux et al, 2007a].…”

“…Chromosome Analysis of 82 Species of Scarabaeoidea (Coleoptera) Cytogenet Genome Res 2012;136:208-219 209 Dutrillaux et al, 2007aDutrillaux et al, , b, 2008Arcanjo et al, 2009;Dutrillaux and Dutrillaux, 2009a;Silva et al, 2009;Oliveira et al, 2010]. However, a major difficulty for NOR localization by silver staining in beetles is that all constitutive heterochromatin is usually stained.…”

Cytogenetic Mapping of rRNAs and Histone H3 Genes in 14 Species of Dichotomius (Coleoptera, Scarabaeidae, Scarabaeinae) Beetles

“…The location of the 45S rDNA has primarily been mapped in representatives of the families Carabidae, Cicindelidae, Scarabaeidae, and Chrysomelidae among others [Sánchez-Gea et al, 2000;Moura et al, 2003;Martínez-Navarro et al, 2004;Bione et al, 2005a;Almeida et al, 2010]. In the family Scarabaeidae, the 45S rDNA has been mapped in a few species (about 20), and the mapping of 5S rRNA and H3 histone genes has been restricted to only 1 species in the order Coleoptera, Dichotomius geminatus [Moura et al, 2003;Vitturi et al, 2003;Bione et al, 2005a, b;Silva et al, 2009;Cabral-deMello et al, 2010a, b;Oliveira et al, 2010].…”

“…Knowledge of the karyotype organization in this genus is restricted to 6 species, revealing primarily the presence of 18 chromosomes and a large metacentric pair (pair 1) [Smith and Virkki, 1978;Vidal, 1984;Cabral-de-Mello et al, 2008;Silva et al, 2009]. The mapping of repeated multigene families, such as 45S rRNA, has been reported for 3 representatives, and the histone H3 and 5S rRNA genes have been mapped in only 1 species.…”