Comparative chromosomal mapping in Triportheus fish species. Analysis of synteny between ribosomal genes

Highly conserved Z and molecularly diverged W chromosomes in the fish genus Triportheus (Characiformes, Triportheidae)

“…CF Yano et al Z chromosome was reported in T. venezuelensis and T. angulatus (Nirchio et al, 2007;Marquioni et al, 2013) that represent two of the most recently derived species, as their lineage originated at 5.2 ± 2.3 and 2.6 ± 1.4 Myr, respectively (Mariguela et al, 2016). Considering the fact that most species, including those originated from older Triportheus lineages, do not show an 18S rDNA cluster on the Z chromosome, it is more plausible to assume that these sequences were firstly translocated onto W and latter transposed from the W to the Z chromosome in T. venezuelensis and T. angulatus in independent events.…”

“…In fact, both techniques were critical to demonstrate the sequences that are still shared by both sex chromosomes or, otherwise, that those are more exclusive to one of them. Noteworthy, it was evidenced that the end of the Wq has a high concentration of female-specific sequences (Figures 2-4), where an 18S rDNA cluster is also located in all Triportheus species so far analyzed (Artoni and Evolution of sex chromosomes in congeneric species CF Yano et al Bertollo, 2002;Nirchio et al, 2007;Diniz et al, 2009;Marquioni et al, 2013;Yano et al, 2014). Sex chromosomes carrying 18S rDNA sequences have already been reported in several other vertebrates, such as Characidium fishes (Scacchetti et al, 2015), cane toad Bufo marinus (Abramyan et al, 2009), Chinese softshell turtle Pelodiscus sinensis (Kawai et al, 2007) and tiger snake Notechis scutatus (O'Meally et al, 2010).…”

“…18S and 5S rDNA sequences were mapped on female chromosome preparations of T. signatus species, following the protocol described in Marquioni et al (2013). For this experiment, the 18S and 5S rDNA probes were labeled with SpectrumOrange-dUTP and SpectrumGreen-dUTP, respectively, using nicktranslation method (Roche).…”

“…The Z is a metacentric chromosome, the largest one in the karyotype, whereas the W is always smaller than the Z, and varies in size and morphology among species (Bertollo and Cavallaro, 1992;Sánchez and Jorge, 1999;Artoni et al, 2001;Artoni and Bertollo, 2002;Nirchio et al, 2007;Diniz et al, 2008;Yano et al, 2014Yano et al, , 2016. Besides, the W chromosome is rich in heterochromatin and carries an 18S ribosomal DNA (rDNA) site on its long arms (Artoni and Bertollo, 2002;Nirchio et al, 2007;Diniz et al, 2009;Marquioni et al, 2013;Yano et al, 2014;Schmid et al, 2016). Recently, a molecular phylogeny of the Triportheidae family was introduced based on the 16S rRNA and cytochrome b (CytB) mitochondrial genes, and on the recombination activating gene 1 (Rag1), recombination activating gene 2 (Rag2) and myosin heavy chain 6 cardiac muscle-α (Myh6) nuclear genes (Mariguela et al, 2016).…”

Comparative cytogenetic mapping of rRNA genes among naked catfishes: implications for genomic evolution in the Bagridae family

“…This may also explain why most vertebrates maintain this configuration. However, H. wyckii is the only species of the Bagridae family in which the 2 ribosomal genes are co-located, a scarce situation among fishes that has been reported in some species such as Prochilodus lineatus (Jesus and MoreiraFilho, 2003), Prochilodus argenteus (Hatanaka and Galetti, 2004), Salmo salar (Pendás et al, 1994), Oncorhynchus mykiss (Morán et al, 1996), fish of the sturgeon family (Fontana et al, 2003), and others (Cross et al, 2006;Marquioni et al, 2013).…”