Padrões de organização dos microcromossomos em espécies da família Picidae e novo método de obtenção de cromossomos de aves

Abstract

In the last decades, cytogenetics has added important results for the evolutionary study of the karyotype of birds. The Picidae family, which includes woodpeckers, comprises about 217 species distributed in almost all terrestrial environments on the planet. Despite the few cytogenetic studies in woodpecker species, interesting results were observed, such as the Z sex chromosome being the largest element of the karyotype, high variation in the diploid number and in the proportion of repetitive sequences. These characteristics influenced the choice of the Picidae family for the development of this thesis. Considering that cytogenetic studies require high quality chromosomal preparations, in Chapter I a new method for chromosome harvesting from avian embryos was developed, which proposes a cheap and fast technique for the production of high quality samples for classical and molecular cytogenetics. In Chapter II was carried out the characterization of the chromosomal complement of four woodpeckers, and Picumnus nebulosus species was described for the first time. In addition, the organization of microchromosomes of these species was described through Fluorescent in situ Hybridization (FISH) analysis with microchromosome probes from Gallus gallus, where an unprecedented rearrangement can be observed in Veniliornis spilogaster, a fusion of a microchromosome followed by a break and inversion. Multiple fusions involving microchromosomes in Melanerpes candidus, the conservation of these elements in Picumnus nebulosus and a few fusions in Colaptes campestris. In the last one, Chapter III, were described contributions and experiences during the internship doctoral abroad.