Heterochromatin organization and chromosome mapping of rRNA genes and telomeric DNA sequences in the burbotLota lota(Linnaeus, 1758) (Teleostei: Gadiformes: Lotidae)

Abstract

AbstractThe knowledge about the genome of the burbot Lota lota (Linnaeus, 1758), the only freshwater gadiform fish (Gadidae, Gadiformes), is limited to chromosome number (2n = 48, NF = 78). In this work analysis of burbot chromosomes by C-banding, DAPI staining and restriction endonuclease digestion proved both heterogeneity of the heterochromatin and interchromosomal differences in the vulnerability to the endonuclease treatment. Silver nitrate and chromomycine A3 staining and fluorescence in situ hybridization using 28S rDNA probes showed that nucleolus organizer regions appear in one pair of burbot chromosomes. There is also a single locus for 5S rDNA repeats exhibited in burbot; however, major and minor rRNA gene families are not linked. The single and separated location of major and minor rDNA families suggests that the burbot karyotype still retains some characteristics of the putative ancestral karyotype. Although the increased number of the chromosome arms in relation to the ancestral karyotype su...