CYTOGENETICS OF THE ANTARCTIC ICEFISH CHAMPSOCEPHALUS-GUNNARI LONNBERG, 1905 (CHANNICHTHYIDAE, NOTOTHENIOIDEI)

Traditional karyotyping and molecular cytogenetic techniques were used to study the chromosomes of Champsocephalus gunnari from the Indian S ector of the Antarctic Ocean. C. gunnari has 24 pairs of chromosomes, giving a diploid number of 48. Most are acrocentric, six are metacentr ic and submetacentric and the level of divergence from the supposed an cestral notothenioid karyotype remains low. The chromosomal features o f this icefish do not differ very much from those of the other channic hthyids, the karyotypic macrostructure being kept stable in these fish es. Although providing relevant basic biological information, traditio nal cytogenetics do not allow a significant comparative analysis betwe en species in this notothenioid family. Molecular cytogenetic techniqu es such as in situ hybridization have been successfully used on C. gun nari, opening new opportunities for a deeper characterization of Antar ctic 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. (C) 1997 Elsevier Science Inc.