Sex chromosome system ZZ/ZW in Apareiodon hasemani Eigenmann, 1916 (Characiformes, Parodontidae) and a derived chromosomal region

Abstract

Parodontidae fish show few morphological characteristics for the identification of their representatives and chromosomal analyses have provided reliable features for determining the interrelationships in this family. In this study, the chromosomes of Apareiodon hasemani from the São Francisco River basin, Brazil, were analyzed and showed a karyotype with 2n = 54 meta/submetacentric chromosomes, and a ZZ/ZW sex chromosome system. The study revealed active NORs located on pair 11 and additional 18S rDNA sites on pairs 7 and 22. The 5S rDNA locus was found in pair 14. It showed a pericentric inversion regarding the ancestral condition. The satellite DNA pPh2004 was absent in the chromosomes of A. hasemani, a shared condition with most members of Apareiodon. The WAp probe was able to detect the amplification region of the W chromosome, corroborating the common origin of the system within Parodontidae. These chromosomal data corroborate an origin for the ZW system of Parodontidae and aid in the understanding of the differentiation of sex chromosome systems in Neotropical fishes.

In situ Localization of (GATA)n and (TTAGGG)n Repeated DNAs and W Sex Chromosome Differentiation in Parodontidae (Actinopterygii: Characiformes)

“…The family Parodontidae has been used in studies of sex chromosome differentiation, investigating the invasion of repetitive sequences and the increase in W chromosome size [Centofante et al, 2002;Rosa et al, 2006;Vicari et al, 2006;Bellafronte et al, 2009Bellafronte et al, , 2011Bellafronte et al, , 2012Schemberger et al, , 2014. In this study, in situ localization of the (GATA)n sequence revealed the accumulation of this microsatellite in proto-sex and sex chromosomes of 7 species: A. hasemani , A. ibitiensis , Apareiodon sp., P. hilarii , A. affinis , P. cf.…”

“…and P. hilarii showed the ZZ/ZW heteromorphic system, while A. affinis presents the ZZ/ZW 1 W 2 system ( figs. 1 , 2 ) Bellafronte et al, 2012].…”

“…On the other hand, the (GATA)n repeat accumulates increasingly in the W chromosome in species with sex chromosomes. Within the species studied, A. hasemani has a W chromosome with lower molecular differentiation, with heterochromatic bands in the short arm and the terminal region of the long arm [Bellafronte et al, 2012].…”

Construction and Characterization of a Repetitive DNA Library in Parodontidae (Actinopterygii: Characiformes): A Genomic and Evolutionary Approach to the Degeneration of the W Sex Chromosome

“…15 Cytogenetic studies reported a conserved diploid number of 54 chromosomes in Parodontidae with distinctive karyotype formulae and numerical/position variation of 18S and 5S rDNA sites. [16][17][18][19][20][21] In this group, two probes for repetitive DNAs have been described: pPh2004 16 and WAp, 17 isolated by genomic digestion and chromosome microdissection, respectively. In addition, this Neotropical fish group is interesting for genetics studies because there are species without heteromorphic sex chromosomes, species with protosex chromosomes, species with a ZZ/ZW sex chromosome system, and species with a multiple ZZ/ZW 1 W 2 sex chromosome system.…”

“…In addition, this Neotropical fish group is interesting for genetics studies because there are species without heteromorphic sex chromosomes, species with protosex chromosomes, species with a ZZ/ZW sex chromosome system, and species with a multiple ZZ/ZW 1 W 2 sex chromosome system. [17][18][19][20][21] Furthermore, researchers have proposed that in Parodontidae the spreading of the repeat elements is the major event leading to genome rearrangements. [17][18][19] Thus, in this study, we isolated and characterized several classes of repetitive DNAs to gain a greater understanding of the dynamics of these genomic sequences in karyotypes and of the mechanism of W sex chromosome differentiation in Parodontidae.…”