Chromosomal diversification of reef fishes from genus Centropyge(Perciformes, Pomacanthidae)

Abstract

The genus Centropyge is remarkable for species richness, composing a highly specialized fish group amongst members from family Pomacanthidae. However, cytogenetical reports are nearly absent in these animals. New data are provided from karyotypical studies carried out on Centropyge aurantonotus from the Brazilian coast of the Atlantic Ocean and C. ferrugatus from the Philippines Sea of the Indo-Pacific Ocean. Both species present 2n = 48 but karyotypes are differentiated by fundamental number. C. aurantonotus has a great number of biarmed chromosomes (4 m + 14 sm + 16 st + 4 a), while C. ferrugatus presents only acrocentric chromosomes. Single nucleolar organizer regions (NORs) are located at interstitial position of an acrocentric pair in C. ferrugatus and on short arms of a subtelocentric pair in C. aurantonotus, as confirmed by fluorescent in situ hybridization (FISH) with 18S rDNA probes. Heterochromatin is distributed over NOR and centromeric regions in both species, but additional GC-rich heterochromatic blocks on short arms of up to eight chromosomal pairs can be detected in C. aurantonotus. 5S rDNA segments were located interstitially on two chromosomal pairs in C. ferrugatus and on nine pairs in C. aurantonotus, mostly equivalent to heterochromatic blocks on short arms of biarmed chromosomes. C. ferrugatus can be considered a species in which basal chromosomal features proposed for modern Teleosteans were conserved. The derived karyotype pattern of C. aurantonotus seems to be determined by pericentric inversions and heterochromatin addition which probably determined the notorious dispersion of 5S rRNA (pseudo)genes. It is demonstrated that, even within a group generally characterized by cytogenetical homogeneity as the family Pomacanthidae, diversified karyotypes can be found.

Inheritance of a Dominant Spotted Melanic Mutation in the Livebearing Fish Phalloceros caudimaculatus var. reticulata from "Banados del Este" Reserve of Biosphere Site in Uruguay

“…The origin of biarmed chromosomes from acrocentric ones could be related to some types of chromosome rearrangements such as pericentric inversions and/or heterochromatin addition. These chromosome rearrangements were previously reported in other Cyprinodontiformes fishes (García et al 1995), in reef fishes from the genus Centropyge (Affonso and Galetti Jr. 2005), in the genus Hypostomus (Artoni and Bertollo 1999) and in "bitterlings" of the family Cyprinidae (Ueda et al 2001). The partial or whole heteropycnotic biarmed chromosomes found in our analyses were also heterochromatic by means of C-banding.…”

Chromosomal localization of rDNA genes and genomic organization of 5S rDNA in Oreochromis mossambicus, O. urolepis hornorum and their hybrid

“…Chromosome banding techniques and fluorescent in situ hybridization (FISH) have been demonstrated to be useful cytogenetic methods for chromosome identification, which has allowed further resolution of similar size chromosomes (Martins and Galetti 2001;Yi et al 2003;Affonso and Pedro 2005;Zhu et al 2006;Zhu and Gui 2007;Morescalchi et al 2008;Mazzuchelli and Martins 2009). In fish, the 5S rDNA multi-gene family consists of a highly conserved coding sequence of 120 bp forming arrays of hundreds to thousands of tandem copies that are separated from each other by variable non-transcribed spacers (NTSs) (Long and David 1980).…”

Triploid origin of the gibel carp as revealed by 5S rDNA localization and chromosome painting

“…Triploid origin has been suggested referring to its bisexual related species crucian carp (Carassius auratus Linnaeus) with 100 chromosomes, but the karyotypes were generally classified as diploid types because of lack of sufficient genetic evidence (Zhou & Gui 2002). Fluorescence in-situ hybridization (FISH) with labeled 5S rDNA probes is a useful cytogenetic method for chromosome identification (Murakami & Fujitani 1998, Wasko et al 2001, Affonso & Pedro 2005. In fish the 5S rRNA multi-gene family consists of a highly conserved coding sequence of 120 bp forming arrays of hundreds to thousands of tandem copies, which are separated from each other by variable non-transcribed spacers (NTS) (Long & David 1980).…”