title: Repetitive sequences associated with differentiation of W chromosome in Semaprochilodus taeniurus.
abstract: The possible origins and differentiation of a ZZ/ZW sex chromosome system in Semaprochilodus taeniurus, the only species of the family Prochilodontidae known to possess heteromorphic sex chromosomes, were examined by conventional (C-banding) and molecular (cross-species hybridization of W-specific WCP, Fluorescence in situ hybridization (FISH) with telomere (TTAGGG)n, and Rex1 probes) cytogenetic protocols. Several segments obtained by W-specific probe were cloned, and the sequences localized on the W chromosome were identified by DNA sequencing and search of nucleotide collections of the NCBI and GIRI using BLAST and CENSOR, respectively. Blocks of constitutive heterochromatin in chromosomes of S. taeniurus were observed in the centromere of all autosomal chromosomes and in the terminal, interstitial, and pericentromeric regions of the W chromosome, which did not demonstrate interstitial telomeric sites with FISH of the telomere probe. The Rex1 probe displayed a compartmentalized distribution pattern in some chromosomes and showed signs of invasion of the pericentromeric region in the W chromosome. Chromosomal painting with the W-specific WCP of S. taeniurus onto its own chromosomes showed complete staining of the W chromosome, centromeric sites, and the ends of the Z chromosome, as well as other autosomes. However, cross-species painting using this WCP on chromosomes of S. insignis, Prochilodus lineatus, and P. nigricans did not reveal a proto-W element, but instead demonstrated scattered positive signals of repetitive DNAs. Identification of the W-specific repetitive sequences showed high similarity to microsatellites and transposable elements. Classes of repetitive DNA identified in the W chromosome suggested that the genetic degeneration of this chromosome in S. taeniurus occurred through accumulation of these repetitive DNAs.
authors: Laboratório de Genética Animal, Instituto Nacional de Pesquisas da Amazônia, Av. André Araújo, 2936, Petrópolis, Manaus, AM, 69011-970, Brazil. leandra@inpa.gov.br
authors: Maria Leandra
authors: ML
authors: Terencio
authors: Carlos Henrique
authors: CH
authors: Schneider
authors: Maria Claudia
authors: MC
authors: Gross
authors: Viviane
authors: V
authors: Nogaroto
authors: Mara Cristina
authors: MC
authors: de Almeida
authors: Roberto Ferreira
authors: RF
authors: Artoni
authors: Marcelo Ricardo
authors: MR
authors: Vicari
authors: Eliana
authors: E
authors: Feldberg
mesh_terms: D000818:Animals; D060125:Characiformes / Q000235:genetics*; D020223:Chromosome Painting / Q000379:methods; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics / Q000302:isolation & purification*; D005260:Female; D023281:Genomics; D006570:Heterochromatin / Q000235:genetics / Q000302:isolation & purification; D007091:Image Processing, Computer-Assisted; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D012091:Repetitive Sequences, Nucleic Acid; D017422:Sequence Analysis, DNA; D012730:Sex Chromosomes / Q000235:genetics*; D016615:Telomere / Q000235:genetics
chemical_list: D006570:Heterochromatin; D004247:DNA