Karyotypic conservatism in five species of Prochilodus (Characiformes, Prochilodontidae) disclosed by cytogenetic markers

Abstract

The family Prochilodontidae is considered a group with well conserved chromosomes characterized by their number, morphology and banding patterns. Thence, our study aimed at accomplishing a cytogenetic analysis with conventional methods (Giemsa staining, silver staining of the nucleolus organizer regions-AgNOR, and C-banding) and fluorescence in situ hybridization (FISH) with 18S and 5S ribosomal DNA probes in five species of the Prochilodus genus (Prochilodus argenteus, Prochilodus brevis, Prochilodus costatus, Prochilodus lineatus and Prochilodus nigricans) collected from different Brazilian hydrographic basins. The results revealed conservatism in chromosome number, morphology, AgNORs 18S and 5S rDNAs location and constitutive heterochromatin distribution patterns. The minor differences observed in this work, such as an Ag-NOR on a P. argenteus chromosome and a distinct C-banding pattern in P. lineatus, are not sufficient to question the conservatism described for this group. Future work using repetitive DNA sequences as probes for FISH will be interesting to further test the cytogenetic conservatism in Prochilodus.

B chromosomes in the species Prochilodus argenteus (Characiformes, Prochilodontidae): morphologicalidentity and dispersion

“…No morphological differentiation between males and females was detected, confirming data published by Pauls and Bertollo (1983, 1990), Hatanaka and Galleti Jr. (2004) and, more recently by Voltolin et al (2013). This karyotype identity, also present in other species already described is a conserved feature in the genus Prochilodus , and it may be identified also among the components of related groups (Galetti Jr. et al 1994, Arai 2011).…”

“…Similarly, analysis of in situ hybridization using 5S and 18S rDNA probes did not reveal the presence of these genes in the supernumerary chromosomes (Figure 4). Visible signs of hybridization were observed in sinteny in one pair of chromosomes in the normal complement, as previously reported by Hatanaka and Galleti Jr. (2004) and Voltolin et al (2013).…”

First cytogenetic analysis of Ichthyoelephas humeralis (Günther, 1860) by conventional and molecular methods with comments on the karyotypic evolution in Prochilodontidae

“…These characteristics are difficult to compare quantitatively to other Prochilodontidae species. Nevertheless, this heterochromatin distribution is different regarding the particular pattern in other species of Prochilodontidae, which show heterochromatin typically restricted to the centromeric and pericentromeric regions of their chromosomes (Oliveira et al 2003, Vicari et al 2006, Terencio et al 2012b, Voltolin et al 2013). …”

“…Ribosomal sites in Prochilodontidae (5S and 18S ribosomal clusters) are syntenic, commonly located in the interstitial position on chromosome pair 2 in all species of Prochilodus and Semaprochilodus analyzed (Pauls and Bertollo 1990, Oliveira et al 1997, 2003; Venere et al 1999, Cavallaro et al 2000, Maistro et al 2000, Jesus and Moreira-Filho 2003, Hatanaka and Galetti Jr. 2004, Artoni et al 2006, Vicari et al 2006, Gras et al 2007, Voltolin et al 2009, 2013, Jorge et al 2011, Terencio et al 2012a, 2012b, Penitente et al 2015). …”

Interregional cytogenetic comparisons in Halichoeres and Thalassoma wrasses (Labridae) of coastal and insular regions of the southwestern Atlantic

“…In the two Halichoeres species, all the 5S rDNA sites exhibit a syntenic 18S/5S arrangement. Syntenic arrangements of ribosomal genes are a derived condition in Perciformes (Nakajima et al, 2012;Calado et al, 2014;Costa et al, 2016) and Characiformes (Voltolin et al, 2013), and this exclusive feature in both Halichoeres species demonstrates that this organization does not interfere with the gene function. The similarity in the organization of ribosomal genes in the Thalassoma and Halichoeres genera indicates a symplesiomorphic condition in the Julidini species.…”