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 metaphas e chromosomes of the same species by fluorescence in situ hybridizatio n (FISH). The hybridization signal appeared over the whole heterochrom atic arm of the submetacentric chromosomes bearing the nucleolar organ izer regions. The results of rDNA/FISH are compared with those coming from classical cytogenetic (C, Q, Ag-NOR, chromomycin A3) banding tech niques. The in situ detection of a specific DNA sequence offers a new more precise perspective for understanding the evolving process in chr omosomes of Antarctic fish and will provide an interesting contributio n to comparative cytogenetics of lower vertebrates.