Cytogenetics of the Antarctic icefish Champsocephalus gunnari Loennberg, 1905 (Channichthyidae, Notothenioidei)

Traditional karyotyping and molecular cytogenetic techniques were used to study the chromosomes of Champsocephalus gunnari from the Indian Sector of the Antarctic Ocean. C. gunnari has 24 pairs of chromosomes, giving a diploid number of 48. Most are acrocentric, six are metacentric and submetacentric and the level of divergence from the supposed ancestral notothenioid karyotype remains low. The chromosomal features of this icefish do not differ very much from those of the other channichthyids, the karyotypic macrostructure being kept stable in these fishes. Although providing relevant basic biological information, traditional cytogenetics do not allow a significant comparative analysis between species in this notothenioid family. Molecular cytogenetic techniques such as in situ hybridization have been successfully used on C. gunnari, opening new opportunities for a deeper characterization of Antarctic fish chromosomes. The in situ location of specific DNA sequences could provide valuable new information for phylogenetic reconstruction, and shed light on the relationship between chromosome change and the evolutionary process.