Sitogenetic and genotoxic investigation of Pelophylax ridibundus from Karasu basin, Rrzurum

Karasu Basin, in Erzurum boundary, is the source of the Euphrates River. It is considered that artificial fertilizers, insecticides, municipal sewage, industrial and factory wastes are polluted the basin. The pollution in the Karasu Basin also threatens the Euphrates basin. During the last few years, many amphibian populations have been decreasing dramatically by environmental pollution. An amphibian species marsh frogs (Pelophylax ridibundus) are distributed in Karasu Basin. The karyotypic characteristics of Pelophylax ridibundus have been investigated by examining metaphase chromosomes spreads obtained from bone marrow and intestine epithelium. The frogs used in the study were caught from three stations of the Karasu Basin. The frogs were transported to the laboratory as live, and kept in aquarium before the analysis. Bone marrow and intestine of frogs were used for karyotype analysis. The best treatment parameters for preparing good metaphase chromosome spreads from the cells were optimized as hypotonic 1 hour (0.075 M KCl) treatment, fixation with carnoy solution (3 methanol: 1 acetic acid) and stained 10% Giemsa for 20 minutes. The prepared mitotic chromosomes were also analysed silver staining (AgNOR) and C-banding techniques. It was determined that Pelophylax ridibundus had 2n=26 chromosomes by investigation of the chromosome spreads. Pelophylax ridibundus karyotypes were determined as being composed of 7 metacentric, 5 submetacentric and 1 subtelocentric chromosome pairs (14M+10SM+2ST). The fundamental arm numbers of chromosomes were determined FN=52 and Ag-NOR positions located in the long arm of chromsome pair 10. The C-banded karyotypes showed C-positive heterochromatin bands at the telomeric regions of the chromosomes. Karyotype symmetry/asymmetry index was 1.53. Secondly, to determine the environmental pollution effects, we performed the genotoxicity studies in Pelophylax ridibundus frogs collected at agricultural areas in the Karasu Basin (Dereboğazı Village and Söğütlü Village). Genotoxicity assays such as erythrocytic nuclear abnormalities (ENA) were carried out on the frogs studied. ENA named kidney-shaped nucleus, notched nucleus and lobed nucleus were assessed in peripheral blood erythrocytes of the frog. The genotoxic effects did not show significant increasing between frog species caught from Dereboğazı Village, statistically. However, the toxic effects increased in Söğütlü Village and this increase was found to be statistically significant.