Ribosomal RNA location in the Antarctic fish Champsocephalus gunnari (Notothenioidei, Channichthyidae) using banding and fluorescence in situ hybridization.

A biotinylated 28S rDNA probe was prepared from the genomic DNA of the Antarctic ice-fish Champsocephalus gunnari and hybridized to metaphase chromosomes of the same species by fluorescence in situ hybridization (FISH). The hybridization signal appeared over the whole heterochromatic arm of the submetacentric chromosomes bearing the nucleolar organizer regions. The results of rDNA/FISH are compared with those coming from classical cytogenetic (C, Q, Ag-NOR, chromomycin A3) banding techniques. The in situ detection of a specific DNA sequence offers a new more precise perspective for understanding the evolving process in chromosomes of Antarctic fish and will provide an interesting contribution to comparative cytogenetics of lower vertebrates.