Cytogenetic characterization of Rhomboplites aurorubens and Ocyurus chrysurus, two monotypic genera of Lutjaninae from Cubagua Island, Venezuela, with a review of the cytogenetics of Lutjanidae (Teleostei: Perciformes)

Abstract

Lutjanidae, commonly known as snappers, includes 105 species, grouped in four subfamilies. In spite of the high number of species and of its worldwide distribution, the family has been little investigated and the phylogenetic relationships among some of its genera and species are still cause for debate. Only a small number of the species has been cytogenetically analysed. This study reports the first description of the karyotype of Rhomboplites aurorubens as well as data concerning the distribution of the constitutive heterochromatin and the location of the 18S rRNA and the 5S rRNA genes. Specimens of Ocyurus chrysurus from Venezuela were also investigated for the same cytogenetic features. Both species have a 48 uniarmed karyotype, but R. aurorubens has a single subtelocentric chromosome pair, the smallest of the chromosome complement, among the other acrocentric chromosomes. The C-positive heterochromatin is limited to the pericentromeric regions of all chromosomes. Both species show a single chromosome pair bearing the Nucleolus Organizer Regions, but NORs are differently located, in a terminal position on the short arms of the smallest chromosomes in R. aurorubens and in a paracentromeric position in a chromosome pair of large size in O. chrysurus. In O. chrysurus, the 5S rDNA gene cluster is located on a medium-sized chromosome pair, whereas in R. aurorubens it is syntenic with the 18S rDNA gene cluster on chromosome pair number 24. The obtained cytogenetic data, along with previous cytogenetic, morphological and molecular data for the family, reinforce the proposal to synonymize genus Ocyurus with Lutjanus. A review of Lutjanidae cytogenetics is also included.Lutjanidae, comumente conhecidos como snappers, inclui 105 espécies, reunidas em quatro subfamílias. A despeito do grande número de espécies e de sua distribuição mundial, a família tem sido pouco estudada e as relações filogenéticas entre alguns de seus gêneros e espécies ainda é motivo de debates. Apenas um pequeno número de espécies foi citogeneticamente analisada. Esse estudo apresenta a primeira descrição do cariótipo de Rhomboplites aurorubens assim como dados relativos à distribuição de heterocromatina constitutiva e localização dos genes 18S rRNA e 5S rRNA. Espécimes de Ocyurus chrysurus da Venezuela foram também analisados quanto às mesmas características citogenéticas. Ambas as espécies têm cariótipos compostos de 48 cromossomos com um único braço, entretanto R. aurorubens tem um único par de cromossomos subtelocêntrico, o menor do complemento cromossômico, entre os outros cromossomos acrocêntricos. A heterocromatina C-positiva é limitada à região pericentromérica de todos os cromossomos. Ambas as species apresentam um único par com Regiões Organizadoras de Nucléolo, mas as RONs são localizadas em posições diferentes, em posição terminal no braço curto dos menores cromossomos de R. aurorubens e em posição paracentromérica no braço longo de um par de cromossomos grandes de O. chrysurus. Em O. chrysurus, os genes 5S rDNA estão localizados em u...

Phylogenetic relationships of tropical western Atlantic snappers in subfamily Lutjaninae (Lutjanidae: Perciformes) inferred from mitochondrial DNA sequences

“…Species known or suspected of hybridization with Ocyurus now include L. synagris and L. griseus (Domeier & Clarke (1992), L. jocu (Bortone & Williams, 1986), and L. apodus and L. analis (Carson & Gold, unpubl.). Placement of Ocyurus into Lutjanus also is consistent with, although not necessarily strongly supported by, the mtDNA phylogenies generated by Sarver et al (1996) and Rodríguez-Santiago (2008), and with the cytogenetic studies of Nirchio et al (2009). To our knowledge, no one has questioned whether Rhomboplites also should be included in Lutjanus, although inclusion of Rhomboplites within Lutjanus was reflected in, but not strongly supported by, the studies of Sarver et al (1996) and Rodríguez-Santiago (2008).…”

“…Placement of Ocyurus into Lutjanus also is consistent with, although not necessarily strongly supported by, the mtDNA phylogenies generated by Sarver et al . (1996) and Rodríguez‐Santiago (2008), and with the cytogenetic studies of Nirchio et al . (2009).…”

Karyotype characterization of Mugil incilis Hancock, 1830 (Mugiliformes: Mugilidae), including a description of an unusual co-localization of major and minor ribosomal genes in the family

“…However, evidence of colocalization of 5S and 18S rDNA has been reported for some species of Acipenseriformes (Fontana et al, 2003), Salmoniformes (e.g., Pendas et al, 1994;Moran et al, 1996;Fujiwara et al, 1998;Rossi & Gornung, 2005), Cypriniformes (Inafuku et al, 2000), Characiformes (e.g., Almeida-Toledo et al, 2002;Cioffi et al, 2009;Diniz et al, 2009 and references therein), Perciformes (Nirchio et al, 2009;Pisano & Ghigliotti, 2009) and, now also, Mugiliformes (present study). Interestingly, all the possible syntenic conditions have been found, either the two sets of genes in distinct and disjoint chromosomal regions, as in Astyanax scabripinnis (Mantovani et al, 2005) and Parodon tortuosus (=Parodon nasus) (Vicente et al, 2001), or in adjacent regions, as in M. incilis (present study) and Triportheus nematurus (Diniz et al, 2009), or the 5S rRNA genes interspersed along the clusters of 45S rDNA, as in Notothenioidei (Pisano & Ghigliotti, 2009).…”

Karyotype of the invasive species Pterois volitans (Scorpaeniformes: Scorpaenidae) from Margarita Island, Venezuela

“…The presence of clusters of these sequences either very close to or far apart from each other on the same chromosome has already been reported in teleosts including Salmo salar (Pendás et al, 1994), Oncorhynchus mykiss (Morán et al, 1996), Acheilognathus tabira subsp. 1, Cyprinus carpio (Inafuku et al, 2000), Rhomboplites aurorubens (Nirchio et al, 2009) and Mugil incilis (Hett et al, 2011). Although the terminal localization of single major ribosomal genes on the short arm of a pair of chromosomes seems to be a shared feature among the species of lionfish cytogenetically studied until now (Caputo et al, 2003;this paper), reports on co-localization of 18S and 5S ribosomal genes in P. volitans, as revealed by the multi-colour FISH are restricted to this study.…”