Karyotypic characterization and genomic organization of the 5S rDNA in Erpetoichthys calabaricus (Osteichthyes, Polypteridae)

Autor: Maria Alessandra Morescalchi, Innocenza Liguori, Vincenzo Stingo, Lucia Rocco
Přispěvatelé: M. A., Morescalchi, I., Liguori, Rocco, Lucia, Stingo, Vincenzo
Rok vydání: 2006
Předmět:
Zdroj: Genetica. 131:209-216
ISSN: 1573-6857
0016-6707
DOI: 10.1007/s10709-006-9119-0
Popis: Polypterids are a group of Osteichthyan fish whose evolutionary relationships with closer basal ray-finned and lobe-finned fish have been disputed since their discovery. Very little is known about the evolutive karyology in the whole Polypteriformes group. In order to fill this gap, a cytogenetic analysis of Erpetoichthys calabaricus species was performed, using both classical and molecular techniques. Karyotype structure (2n = 36; FN = 72), chromosome location of telomeric sequences (TTAGGG) n and ribosomal 5S and 18S rRNA genes were examined in twenty specimens of E. calabaricus by using Ag-NOR, classical C-banding, sequential CMA3/4′,6-diaminidino-2-phenylindole (DAPI) staining and fluorescent in situ hybridization (FISH). CMA3 marked all centromerical and some (n°1 and n°15) telomeric regions. Staining with Ag-NOR and CMA3 showed the presence of two NORs on the p arm of the chromosome pair n°1. Hybridization with telomeric probes (TTAGGG) n showed signals at the end of all chromosomes. 5S rDNA was cloned and sequenced. After the alignment, the 5S rRNA sequences revealed an organization made up of two different classes of tandem arrays (type I and type II). FISH with 5S rDNA marked the telomeric regions of the small chromosome pair n°15, while FISH with 18S rDNA marked the telomeric region of the pair n°1. The results obtained were compared with cariological data on closer species now available in literature.
Databáze: OpenAIRE
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