Multiple sex chromosomes in the genus Hoplias (pisces: Erythrinidae).

Abstract

Fishes, for the most part, do not exhibit heteromorphic sex chromosomes although they belong to gonochoristic species (Denton 1973, Ohno 1974). Most fishes are thought to have polygenic sex determination. Even though most of these genes are located in a given chromosome pair, if this pair is not heteromorphic it can be defined as a sex pair only by genetic crosses with the use of genetic markers (Denton 1973). Although the occurrence of differentiated sex chromosomes in fishes is not a general rule, several such cases have been reported, since the studies of Nogusa (1960) with Mogrunda obscura (Gobiidae). So, XX/XY mechanisms were reported for some species belonging to different genera as of Bathylagus (

A new sympatric region for distinct karyotypic forms of Hoplias malabaricus (Pisces, Erythrinidae)

“…All the specimens presented 2n = 42 chromosomes, and a probable XX/XY sex chromosome system, which was reanalyzed and confirmed for the fish from the Rio Doce State Park (Born & Bertollo, 2000a). In a complementary study involving specimens from Lagoa Carioca and Lagoa dos Patos, the latter also located in the Rio Doce State Park, Ferreira et al (1989) found the same karyotypic structure previously described by Bertollo et al (1979). However, of the 22 specimens from Lagoa Carioca, a single female individual presented a divergent karyotype, including a specific meta-submetacentric chromosome pair instead of a subtelocentric one.…”

“…Karyotype B is the chromosomal form usually found in H. malabaricus from the Rio Doce State Park (Bertollo et al, 1979;Ferreira et al, 1989;Born & Bertollo, 2000a). With regard to karyotype A, besides the male specimen analyzed here, only one female specimen carrying this same karyotype had been previously reported for specimens from the Lagoa Carioca (Ferreira et al, 1989).…”

“…malabaricus populations in the Juquiá river (São Paulo State, Brazil) and in two lakes of the Rio Doce State Park (Lagoa Dom Helvécio and Lagoa Carioca, MG, Brazil) were previously analyzed by Bertollo et al (1979). All the specimens presented 2n = 42 chromosomes, and a probable XX/XY sex chromosome system, which was reanalyzed and confirmed for the fish from the Rio Doce State Park (Born & Bertollo, 2000a).…”

Evolutionary aspects of the ZZ/ZW sex chromosome system in the Characidae fish, genus Triportheus. A monophyletic state and NOR location on the W chromosome

“…Chromosome spreads were obtained by direct preparations from kidney cells (Bertollo et al, 1978) and by Heredity short-term culture of cells (Fenocchio et al, 1991), using stimulation of mitotic activity (Lee and Elder, 1980).…”

Evidence of an XX/XY sex chromosome system in the fish Dormitator maculatus (Teleostei, Eleotrididae)

“…The ZZ/ZW system is the most common sex chromosome system and the XX/X0 (ten species) and ZZ/Z0 (three species) systems, are the most rare (Devlin and Nagahama, 2002). Cytogenetic differences detected between sex chromosomes include: additions or deletions of C-band positive segments (Phillips and Ihssen, 1985;Andreata et al, 1992Andreata et al, , 1993Cano et al, 1996;Stein et al, 2001), reductions in chromosome size (Park and Kang, 1979), increases in chromosome size (Galetti et al, 1981) and chromosome rearrangements (Uyeno and Miller, 1971;Thorgaard, 1978;Bertollo et al, 1983;Almeida Toledo et al, 1984;Pezold, 1984;Vitturi et al, 1991).…”