Cytogenetic characterization of hybrids offspring betweenColossoma macropomum(Cuvier, 1818) andPiaractus brachypomus(Cuvier, 1817) from Caicara del Orinoco, Venezuela

Abstract

Conventional karyotype and nucleolar organizer regions (NORs) of C. macropomum x P. brachypomus hybrids and parental species are reported. A modal diploid number of 54 chromosomes and a fundamental number (NF) of 108 were found for C. macropomum, P. brachypomus and their hybrids. P. brachypomus shows a pair of silver stained chromosomes, while cells with three and four Ag-NOR bearing chromosomes were observed in C. macropomum. The hybrids consistently presented cells with a single metacentric Ag-NOR bearing chromosome and cells with three Ag-NOR bearing chromosomes. The FISH technique was employed to localize 18S rDNA in the chromosomes of the parentals and the hybrids. In P. brachypomus the FITC signals appeared in the SM pair as when stained with silver salts. In C. macropomum the signals were evidenced in six chromosomes. In the hybrids, as expected, the FITC dots were observed in four chromosomes. All the techniques employed in the present work represent good tools to identify the parentals and distinguish them of the hybrids.

Body color development and genetic analysis of hybrid transparent crucian carp (Carassius auratus)

“…A number of researchers have found that most inter-generic hybrids can fertilize and hatch (Nirchio et al, 2003;Lou and Li, 2006;Hashimoto et al, 2012). This is consistent with our results that demonstrate that fertilization and hatching can be achieved using four inter-generic reciprocal crosses of transparent crucian carp with ornamental carp and red purse carp.…”

Extensive polymorphism and chromosomal characteristics of ribosomal DNA in the characid fish Triportheus venezuelensis (Characiformes, Characidae)

“…Lepisosteus osseus (Ráb et al, 1999), with only one Ag-NOR-bearing chromosome pair, the FISH technique using 18S or 28S sequences usually stains the same chromosome pair. Nevertheless, the presence of a number of major ribosomal cistrons identified by the FISH technique using 18S or 28S sequences higher than that observed with the Ag-NOR technique are more common, having been reported in Salmo truta (Pendás et al, 1993), Astyanax scabripinnis (Ferro et al, 2001), Hyphessobrycon anisitsi (Centofante et al, 2003), Prochilodus lineatus (Jesus and Moreira-Filho, 2003), Colossoma macropomum, Piaractus brachypomus and its interspecific hybrids (Nirchio et al, 2003), and Lebias fasciata (Tigano et al, 2004). These differences have been attributed to the presence of NORs that are usually unexpressed.…”

Karyotype differentiation and cytotaxonomic considerations in species of Serrasalmidae (Characiformes) from the Amazon basin

“…Ag-NORs in Serrasalmidae have been analyzed since the 1980s and have invariably been visualized as multiple sites usually located in the terminal region on the short arms of subtelo-acrocentric chromosomes, although some species bear terminal Ag-NORs on the long arms (Galetti Jr. et al, 1985;Almeida-Toledo et al, 1987;Cestari & Galetti Jr. 1992a, b;Martins-Santos et al, 1994;Nakayama et al, 2001Nakayama et al, , 20022008;Centofante et al, 2002a;Nirchio et al, 2003;Gaviria et al, 2005). However, the numerical variation in these regions (in both inter and intra-specific terms) is much more notable than the positional differences, ranging from four sites in C. macropomum to 12 sites in S. rhombeus (Table 1).…”