Diferenciação genômica e evolução dos cromossomos sexuais em espécies de Omophoita (alticinae) por meio da análise do satelitoma e pintura cromossômica.

Abstract

Molecular cytogenetics analysis and next-generation sequencing (NGS) has been used on few species of Coleoptera. Despite this, there are about 4,800 species analyzed cytogenetically. The beetles include about 380,000 species, among the coleoptera, a group that has been studied are the Oedionychina (Chrysomelidae, Alticinae, Oedionychini). Based on previous research, Oedionychina has shown to have a conserved karyotype, with few species that differ from the basal karyotype (2n=22=10II+X+y), being the only of the class Insecta that possess giant sex chromosomes. Analyses performed in some Oedionychina species have shown that despite their karyotype is structurally and numerically conserved, they have great heterogeneity in relation to banding pattern and location of repetitive DNAs, especially on the sex chromosomes. The objective of this work was to understand the process of differentiation and evolution of sex chromosomes in species of the genus Omophoita, using genomic and chromosomal comparisons. This is the first analysis using GCH (Comparative genomic hybridization) and chromosome painting in Coleoptera and the first comparison of satellite DNA content between sexes in beetles. Comparative intraspecific analysis with CGH performed in O. octoguttata resulted in high genomic similarity between the sexes, only one region with stronger labeling on the Y chromosome was identified, probably the sex-specific region of the male. Comparison with CGH among Omophoita species resulted in a high degree of genomic divergence, showing few sites with shared regions between species. Chromosome painting revealed a high degree of intraspecific and interspecific similarity of the X and Y sex chromosomes. Thus, inferences from chromosome painting may indicate that the sex chromosomes arose from an autosomal pair, and show little molecular differentiation between them. The description of the satellitome in O. octoguttata for male and female resulted in the largest insect satellite found so far. Identification of enriched satellites in the male genome and possibly absent in the female genome, may be associated with sex chromosomes, and involved in their differentiation. In addition, the similarities of some satellites with regions of larger satellites were verified, in order to make evolutionary inferences about the evolution of the satellitome in O. octoguttata. Finally, using low coverage sequencing of the O. octoguttata genome, the mitochondrial genome of the species was assembled. Furthermore, using this data with mitochondrial genomes deposited at Genbank/NCBI, a phylogenetic tree of Alticinae was constructed, which recovered its monophyly as a sister group of Galerucinae.