title: Genomic Organization of Repetitive DNA in Woodpeckers (Aves, Piciformes): Implications for Karyotype and ZW Sex Chromosome Differentiation.
abstract: Birds are characterized by a low proportion of repetitive DNA in their genome when compared to other vertebrates. Among birds, species belonging to Piciformes order, such as woodpeckers, show a relatively higher amount of these sequences. The aim of this study was to analyze the distribution of different classes of repetitive DNA-including microsatellites, telomere sequences and 18S rDNA-in the karyotype of three Picidae species (Aves, Piciformes)-Colaptes melanochloros (2n = 84), Colaptes campestris (2n = 84) and Melanerpes candidus (2n = 64)-by means of fluorescence in situ hybridization. Clusters of 18S rDNA were found in one microchromosome pair in each of the three species, coinciding to a region of (CGG)10 sequence accumulation. Interstitial telomeric sequences were found in some macrochromosomes pairs, indicating possible regions of fusions, which can be related to variation of diploid number in the family. Only one, from the 11 different microsatellite sequences used, did not produce any signals. Both species of genus Colaptes showed a similar distribution of microsatellite sequences, with some difference when compared to M. candidus. Microsatellites were found preferentially in the centromeric and telomeric regions of micro and macrochromosomes. However, some sequences produced patterns of interstitial bands in the Z chromosome, which corresponds to the largest element of the karyotype in all three species. This was not observed in the W chromosome of Colaptes melanochloros, which is heterochromatic in most of its length, but was not hybridized by any of the sequences used. These results highlight the importance of microsatellite sequences in differentiation of sex chromosomes, and the accumulation of these sequences is probably responsible for the enlargement of the Z chromosome.
authors.affiliation: Programa de Pós-graduação em Ciências Biológicas, Universidade Federal do Pampa, São Gabriel, Rio Grande do Sul, Brazil.
authors.forename: Thays Duarte
authors.identifier: http://orcid.org/0000-0003-4131-8210
authors.initials: TD
authors.lastname: de Oliveira
authors.affiliation: Programa de Pós-graduação em Genética e Biologia Molecular, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Rafael
authors.initials: R
authors.lastname: Kretschmer
authors.affiliation: Programa de Pós-graduação em Ciências Biológicas, Universidade Federal do Pampa, São Gabriel, Rio Grande do Sul, Brazil.
authors.forename: Natasha Avila
authors.initials: NA
authors.lastname: Bertocchi
authors.affiliation: Programa de Pós-graduação em Genética, Universidade Federal do Paraná, Curitiba, Paraná, Brazil.
authors.forename: Tiago Marafiga
authors.initials: TM
authors.lastname: Degrandi
authors.affiliation: Laboratório de Cultura de Tecidos e Citogenética, SAMAM, Instituto Evandro Chagas, Ananindeua, Pará, Brazil.|Instituto de Ciências Exatas e Naturais, Universidade Federal do Pará, Belém, Pará, Brazil.
authors.forename: Edivaldo Herculano Corrêa
authors.initials: EH
authors.lastname: de Oliveira
authors.affiliation: Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, São Paulo, São Paulo, Brazil.
authors.forename: Marcelo de Bello
authors.initials: MB
authors.lastname: Cioffi
authors.affiliation: Programa de Pós-graduação em Ciências Biológicas, Universidade Federal do Pampa, São Gabriel, Rio Grande do Sul, Brazil.
authors.forename: Analía Del Valle
authors.initials: AD
authors.lastname: Garnero
authors.affiliation: Programa de Pós-graduação em Ciências Biológicas, Universidade Federal do Pampa, São Gabriel, Rio Grande do Sul, Brazil.
authors.forename: Ricardo José
authors.initials: RJ
authors.lastname: Gunski
mesh_terms: D000818:Animals; D001717:Birds / Q000235:genetics*; D002874:Chromosome Mapping; D016000:Cluster Analysis; D005260:Female; D016678:Genome; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D008297:Male; D018895:Microsatellite Repeats; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics*; D012730:Sex Chromosomes / Q000235:genetics*; D016615:Telomere / Q000235:genetics
chemical_list: D012337:RNA, Ribosomal, 18S