Robertsonian rearrangements in the reef fish Chromis (Perciformes, Pomacentridae) involving chromosomes bearing 5s rRNA genes

Abstract

Cytogenetic studies were done on three Pomacentridae species of the genus Chromis. The karyotype of C. multilineata consisted of 48 acrocentric chromosomes (FN = 48), C. insolata had 2n = 46-47 (3-4M+6SM+36-38A; FN = 56) and C. flavicauda had 2n = 39 (9M+6SM+24A; FN = 54). Robertsonian polymorphisms were detected in C. insolata and C. flavicauda. All three species had small heterochromatic blocks restricted to centromeric regions. Nucleolar organizer regions (NORs) were detected in the telomeric position of a medium acrocentric chromosome pair in C. multilineata and in non-homologous chromosomes in both C. flavicauda and C. insolata. FISH with a telomeric probe detected no internal telomeric sequences in C. flavicauda and C. insolata. 5S rRNA genes were observed in a pericentromeric region of two large metacentric chromosome pairs in C. flavicauda and two large acrocentric pairs in C. insolata. The karyotype structure and the number and location of the 5S rDNA loci in these two species indicated that the 5S rRNA-bearing acrocentric chromosomes were directly involved in the origin of the polymorphisms observed. These data reinforce the idea that Robertsonian rearrangements have been involved in molding the karyotype in the subfamily Chrominae.

Cytogenetic studies in three species of Lutjanus (Perciformes: Lutjanidae: Lutjaninae) from the Isla Margarita, Venezuela

“…However, examples of Robertsonian polymorphism in marine fishes have been reported for species of Gobiidae (Gobius paganellus, Giles et al, 1985;Neogobius eurycephalus, Ene, 2003), Sparidae (Diplodus annularis, Vitturi et al, 1996), Pomacentridae (Chromis insolata and C. flavicauda, Molina & Galetti, 2002), Cottidae (Myoxocephalus scorpius, Yershov, 2005), Gadidae and Pleuronectidae (Gadus morhua and Pleuronectes platessa, Fana & Fox, 1991). In this context, the presence of cytotype II, with a large unpaired metacentric chromosome, found in one male and one unsexed specimen of L. synagris, is quite interesting.…”

The First Report of NORs and Chromosome Analysis of Tripletail Wrasse, Cheilinus trilobatus (Perciformes: Labridae)

“…The occurrence of pericentric inversions seems to represent a frequent rearrangement mechanism of the order Perciformes (Cano et al 1982, Galetti et al 2002, Ueno and Takai 2000, Molina and Galetti 2004b. A NF higher than 48 (C. fasciatus and C. trilobatus), as observed in genus Cheilinus (Ojima andKashiwagi 1979, Ojima 1983), indicates that although less common than in other groups, pericentric inversions constitute one of the main mechanisms of karyotypic diversification within the family Labridae (Souza de Sena and Molina 2007).…”

Atlantic moonfishes: independent pathways of karyotypic and morphological differentiation

“…Similarly to NORs, 5S rDNA sites have proven to be phylogenetically discriminatory markers between several species and populations of marine fish (Motta-Neto et al 2011a, b). Some cases have identified possible participation by 5S sites in chromosome rearrangements (Molina and Galetti 2002). Nevertheless, among Selene species, 5S sequences have demonstrated a conserved condition with low evolutionary dynamics.…”