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 karyotype of Halobatrachus didactylus presents 46 chromosomes, composed of eight metacentric, 18 submetacentric, four subtelocentric, and 16 acrocentric chromosomes. The results of FISH showed that the major ribosomal genes were located in the terminal position of the short arm of a large submetacentric chromosome. They also showed a high variation in the hybridization signals. The products of amplification of 5S rDNA produced bands of about 420 pb. The PCR labeled products showed hybridization signals in the subcentromeric position of the long arm of a submetacentric chromosome of medium size. Double-color FISH indicated that the two ribosomal families are not co-located since they hybridized in different chromosomal pairs. Telomeres of all the chromosomes hybridized with the (TTAGGG)n probe. The GATA probe displayed a strong signal in the long arm of a submetacentric chromosome of medium size, in the subcentromeric position. The double-color FISH showed that the microsatellite GATA and the 5S rDNA gene are located in different chromosomal pairs. The majority presence of GATA probes in one pair of chromosomes is unusual and considering its distribution through different taxa it could be due to evolutionary mechanisms of heterochromatine accumulation, leading to the formation of differentiated sex chromosomes.
Merlo
Alejandro
A
Laboratorio de Genética, Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, Polígono Río San Pedro, Puerto Real, Cadiz, 11510, Spain.
Cross
Ismael
I
Palazón
José Luis
JL
Sarasquete
Carmen
C
Rebordinos
Laureana
L
D000818:Animals; D024541:Batrachoidiformes / Q000145:classification / Q000235:genetics*; D002874:Chromosome Mapping / Q000379:methods*; D004275:DNA, Ribosomal / Q000737:chemistry; D019143:Evolution, Molecular; D005260:Female; D020459:Genes, rRNA; D017404:In Situ Hybridization, Fluorescence / Q000379:methods; D007621:Karyotyping; D008297:Male; D013194:Staining and Labeling
D004275:DNA, Ribosomal