Chromosomal evolution of rDNA and H3 histone genes in representative Romaleidae grasshoppers from northeast Brazil

Abstract

BackgroundGrasshoppers from the Romaleidae family are well distributed in the Neotropical Region and represent a diversified and multicolored group in which the karyotype is conserved. Few studies have been conducted to understand the evolutionary dynamics of multigene families. Here, we report the chromosomal locations of the 18S and 5S rDNA and H3 histone multigene families in four grasshopper species from the Romaleidae family, revealed by fluorescent in situ hybridization (FISH).ResultsThe 5S rDNA gene was located in one or two chromosome pairs, depending on the species, and was found in a basal distribution pattern. Its chromosomal location was highly conserved among these species. The 18S rDNA was located in a single medium-sized chromosomal pair in all species analyzed. Its chromosomal location was near the centromere in the proximal or pericentromeric regions. The location of the H3 histone gene was highly conserved, with slight chromosomal location differences among some species. To our knowledge, this is the first report of a megameric chromosome carrying both the chromosomal markers 18S rDNA and the H3 histone genes, thereby expanding our understanding of such chromosomes.ConclusionsThe 5S and 18S rDNA genes and the H3 histone genes showed a conservative pattern in the species that we analyzed. A basal distribution pattern for 5S rDNA was observed with a location on the fourth chromosomal pair, and it was identified as the possible ancestral bearer. The 18S rDNA and H3 histone genes were restricted to a single pair of chromosomes, representing an ancestral pattern. Our results reinforce the known taxonomic relationships between Chromacris and Xestotrachelus, which are two close genera.

Physical mapping of 18S and 5S rDNA loci and histone H3 gene in grasshopper species of the subfamily Gomphocerinae (Acrididae)

“…The restriction of histone H3 to only one chromosome pair in all species analyzed is in agreement with previous reports on the Acrididae (Cabrero et al, 2009;Palacios-Gimenez et al, 2013) and for other families such as Proscopiidae (Cabral-de-Mello et al, 2011b) and Romaleidae (Anjos et al, 2013;Neto et al, 2013). The dispersion of H3 histone sites in the genomes of members of the family Acrididae has only been reported in three species: Rhammatocerus brasiliensis (Oliveira et al, 2011), A. flavolineata (Bueno et al, 2013), and Dichromatos lilloanus (PalaciosGimenez et al, 2013).…”

“…According to the literature (Cabral-de-Mello et al, 2011a;Oliveira et al, 2011), extensive variation in the number of 5S rDNA sites is common in grasshoppers of the families Acrididae and Romaleidae (Anjos et al, 2013;Neto et al, 2013), although they can be restricted to a single pair of chromosomes as in the Proscopiidae (Cabral-de-Mello et al, 2011b). Acrididae show a range of distribution patterns, from species with single sites to species with sites dispersed throughout all chromosomes, in addition to intermediate situations (Cabral-de-Mello et al, 2011a;Oliveira et al, 2011).…”

Chromosome mapping in Abracris flavolineata (De Geer, 1773) (Orthoptera) from the Iguaçu National Park – Foz do Iguaçu, Paraná, Brazil

“…2c and d). This location is similar in number to that found in most species of grasshoppers, distributed on a single pair of chromosomes (Cabrero et al 2009, Cabral-de-Mello 2011a, 2011b, Neto et al 2013). However, our data differ from those reported for the population of A. flavolineata of southeastern Brazil, in which these genes were observed on all chromosomes, including the X chromosome, but not on B chromosomes (Bueno et al 2013).…”

Short Communication A small B chromosome in the grasshopper Ommexecha virens (Ommexechidae)

“…In Romaleidae, the H3 histone gene distribution pattern in four species was observed for the first time. The H3 histone site was restricted to the second autosomal pair in all species examined (Neto et al, 2013). Regarding CMA 3 /DA/DAPI staining, CMA 3 positive blocks were observed in the pericentromeric regions of the L2, S9, and S10 chromosomal pairs in 0B and 1B individuals.…”