Repetitive DNA chromosomal organization in the cricket Cycloptiloides americanus : a case of the unusual X 1 X 2 0 sex chromosome system in Orthoptera

摘要: A common placement for most sex chromosomes that is involved in their evolutionary histories the accumulation of distinct classes repetitive DNAs. Here, with aim understanding poorly studied DNA organization crickets and its possible role chromosome differentiation, we characterized cricket species Cycloptiloides americanus, a remarkable presence unusual system X1X20♂/X1X1X2X2♀. For these proposes, used C-banding mapping through fluorescence situ hybridization some The distribution highly moderately DNAs (C 0t-1 DNA) varied depending chromosome. greater X2 was evidenced. microsatellites were spread along entire chromosomes, but (AG)10 (TAA)10 less enriched, mainly centromeric areas. Among multigene families, 18S rDNA throughout almost all except pair 5 X2, while U2 snDNA placed exclusively largest Finally, 5S located short arms chromosomes. obtained data reinforce importance chromosomal dissociation inversion as primary mechanism to generate neo-sex studied, followed by accumulation. Moreover exclusive suggests involvement this sequence recognition meiosis and, consequently, maintenance, addition avoiding degeneration.