Pintura cromossômica multidirecional no genoma de synallaxis frontalis (passeriformes, furnariidae)

Abstract

During the evolutionary process the karyotypes of the species were transformed following system not always known, generating an immense chromosomic diversity. Thus the present work aimed to understand the karyotype evolution of a species of the Furnariidae family, Synallaxis frontalis, popularly known as Petrim. The methodology used to reach our aim was classical cytogenetics (giemsa and Cbanding) and molecular (fluorescence in situ hybridization) with 18S ribosomal gene probes and chromosome probes of Gallus gallus (GGA) and Leucopternis albicollis (LAL). The giemsa staining allowed us to infer that the species studied presented a typical karyotype for birds, with 82 chromosomes, most of them microchromosomes. However, the presence of heteromorphisms in the morphology of the first and third autosomal pairs was observed. C-banding demonstrated that constitutive heterochromatin is located primarily in the centromeric/pericentromeric regions of macrochromosomes and microchromosomes and in practically the entire size of the W chromosome. The ribosomal sites were found in a pair of microchromosomes, as in the most of the basal species. The chromosome painting with GGA probes showed that the ancestral chromosomes 1 and 2 are fissioned, whereas the hybridization of the chromosomes corresponding to the GGA 3-10 showed the same standard proposed for the supposed ancestor of the birds. Hybridizations with LAL probes confirmed the results obtained with GGA and allowed the identification of several intrachromosomal rearrangements on chromosome 1 (GGA1q) and chromosome 3 (GGA2q). The inversions on chromosome 1 of Synallaxis frontalis were similar to the inversions already described for Passeriformes, however, this species presented an extra inversion, responsible for the heteromorphism in this chromosome. Similarly, on chromosome 3, the inversion found was also responsible for heteromorphism. This information is important to better understand the genomic organization and chromosomal evolution of birds, particularly for Suboscine.