First karyological analysis of smallmouth lotak, Cyprinion kais Heckel, 1843, an endemic Cyprinid fish from the Tigris–Euphrates Basin

Abstract

Karyotype of the smallmouth lotak, Cyprinion kais Heckel, 1843 (Cyprinidae) was investigated by examining metaphase chromosomes. This study is the first karyological survey on this vulnerable fish species in the Tigris–Euphrates basin. The results can be used for population studies, management and conservation programs. The fish were caught by electrofishing from Godarkhosh River in Ilam province, western Iran, in April 2008 and transported live to the Ichthyology Laboratory of Isfahan University of Technology. Five fish were injected intraperitoneally with two doses of phytohemagglutinin (PHA), 4 μg g−1 bw with a 20-h interval to induce cell divisions. After 8 h in 20°C water, the fish were injected intraperitoneally with colchicine (25–50 μg g−1 bw) to depress cell divisions in the metaphase stage and left for 7 h before sacrificing. Kidney and gill epithelia were used for karyotype analyses. It was determined that C. kais has 2n = 50 chromosomes, consisting of 8 metacentric, 7 submetacentric, 3 subtelocentric and 7 telocentric chromosome pairs. Centromeric index, arm ratio and Fundamental Number (FN) were determined as 0–50, 1–∞, and 86, respectively. The shortest and longest chromosome was a telocentric and a submetacentric one, with 2.61 and 6.88 μm length, respectively.