Conventional karyotype and nucleolar organizer regions of the toadfish <i>Halobatrachus didactylus</i> (Schneider, 1801) (Pisces: Batrachoididae)

Abstract

SUMMARY: For this report, we studied the conventional karyotype and the NOR-bearing chromosomes in the toadfish Halobatrachus didactylus. We found a karyotype of 46 chromosomes made up of 8 metacentric, 12 submetacentric, and 26 acrocentric elements (FN = 66). No heteromorphic sex chromosomes were observed in the species. Metacentric chromosomes were easily classified as homologous pairs according to their morphology and L/S ratio. The rest of the chromosomes could not be accurately classified as homologous pairs because differences in chromosome size and L/S ratio were too slight between adjacent pairs within a size-ranged series. A single pair of NOR-bearing chromosomes was found. Active NORs were terminally located in a submetacentric pair of chromosomes.Key words: karyotype, NOR, cytogenetic, toadfish, Halobatrachus didactylus. RESUMEN: CARIOTIPO Y REGIONES ORGANIZADORAS DEL NUCLEOLO DEL PEZ SAPO MARINO HALOBATRACHUS DIDACTYLUS(SCHNEIDER, 1801) (PISCES: BATRACHOIDIDAE). -Se estudió el cariotipo convencional (Giemsa) y las Regiones Organizadoras del Nucleolo (NOR) en el pez sapo marino Halobatrachus didactylus. El número diploide de cromosomas 2n = 46 estuvo compuesto de 8 elementos metacéntricos, 12 submetacéntricos y 26 acrocéntricos (NF = 66). No fueron observados cromosomas sexuales heteromórficos en esta especie. Los cromosomas metacéntricos fueron fácilmente clasificados como pares homólogos según su morfología y la relación longitud del brazo largo/longitud del brazo corto (L/S). El resto de los cromosomas no pudo ser clasificado con precisión como pares homólogos debido a que las diferencias en el tamaño de los cromosomas y la razón L/S fueron muy pequeñas entre pares adyacentes dentro de la misma serie de tamaños. Fue detectado un par de cromosomas portadores de NOR. Las NOR están localizadas en la región terminal de un par de cromosomas submetacéntricos.Palabras clave: cariotipo, NOR, citogenética, pez sapo marino, Halobatrachus didactylus.

Karyoevolution of the toadfish Thalassophryne nattereri (Batrachoidiformes: Batrachoididae)

“…This result agrees with the pattern reported in several toadfish species (Palazón et al, 2003;Nirchio et al, 2004a,b;Merlo et al, 2007), thus suggesting that single NORs at the telomeric position should be regarded as a symplesiomorphic feature of Batrachoididae. The localization of ribosomal sites in distinct chromosome pairs could validate these regions as potential tools for cytotaxonomic purposes.…”

“…Contradictory karyotypic formulae have been reported in a single species of Batrachoididae (Palazón et al, 2003;Merlo et al, 2007), and some of them are quite discrepant (Nirchio et al, 2002(Nirchio et al, , 2004a. However, the relatively large number of subtelocentric chromosomes in the karyotypes coupled with an imprecise differentiation between subtelocentric and acrocentric chromosomes should account for most of the differences in the number of chromosome arms observed within this family.…”

Chromosomal mapping of the major and minor ribosomal genes, (GATA) n and (TTAGGG) n by one-color and double-color FISH in the toadfish Halobatrachus didactylus (Teleostei: Batrachoididae)

“…The Batrachoides are composed of 71 species belonging to three subfamilies (Froese and Pauly 2005) and are widely distributed by the Atlantic, Pacific, and Indian Oceans. H. didactylus is the only species of this family in the Iberian Peninsula (Palazó n et al 2003) and populations are distributed along the coasts from of the Bay of Biscay to Ghana as well as the western Mediterranean (Roux 1986).…”

The impact of a strong natural hypoxic event on the toadfish Aphos porosus in Coliumo Bay, south-central Chile

“…Although the members of this family are made up of species with no commercial value (Palazón-Fernández et al 2010), they are recognized as important components of ichthyofauna communities in the coastal ecosystems they inhabit (Canto-Maza & Vega-Cendejas 2007, Cortés & Muñoz 2008. Historically, toadfish species have been used in laboratory studies in the field of endocrinology (Hoffman 1963), physiology (Fänge & Wittenberg 1958, Haschemeyer 1969) and animal toxicology (Alquezar et al 2006), among others, and there are increasing efforts to improve knowledge of their basic biology and ecology (Price & Mensinger 1999, Palazón-Fernández et al 2001Palazón et al 2003, Malca et al 2009.…”