Endocrine disruptor compounds (EDCs) are a type of environmental pollutants with both natural and anthropogenic origins. Final destination for most of these pollutants is aquatic environments. Therefore, they can affect aquatic wildlife species through interfering with their endocrine system and causing detrimental effects on them. The aim of this study was the evaluation of some biological characteristics, such as hematological factors, sex ratio, gonado-somatic index (GSI), and vitellogenin (VTG) expression, in Petroleuciscus esfahani caught from Zayandeh Roud River. A total of 323 individuals were collected from four sampling stations: Cheshmeh Dimeh (CHD) and Khersoonak (KH) (located upstream the river), and Chamgordan (CH) and Safaeieh Bridge (SB) (from downstream the river). Averaged length and weight for the specimens from the four stations were 14.93 g and 96 mm, respectively. Evaluation of hematological factors RBC, Hb, HCT and WBC showed no significant differences among stations. But the average percentages of all leukocyte types were significantly higher in CH except for lymphocytes (p<0.05). On the other hand, MCV, MCH and MCHC were significantly lower in CH in comparison to the other sampling stations (p<0.05). In all the stations, sex ratio showed deviations from the expected ratio (1:1) in favor of females, except for SB (Chi square test, p<0.05). Microscopic assessment of the gonads did not show any type of disorder, such as intersex. GSI was compared in males and females from all the stations. The only statistically significant difference was observed in male GSI from CH, which was lower than the male GSI from the other stations (p<0.05). VTG expression was used as a reliable marker for exposure of fish to EDCs with estrogenic properties. For this purpose it was necessary to clone VTG cDNA for the first time in Petroleuciscus esfahani. Results indicated that the full length VTG cDNA consists of 4177 bp, and with its respective putative protein having 1339 amino acids. Evaluation of VTG expression with real-time PCR, using ?-actin as the reference gene, showed relative gene expression in both sexes from all four stations, although it was significantly higher in males and females from CH (p<0.05). In general, the data suggest that Petroleuciscus esfahani fish populations are exposed to EDCs with estrogenic activity, which has affected some of its biological features, such as sex ratio deviation toward females and vitellogenin gene expression in males, as well as altering its expression pattern in the females caught from Zayandeh Roud River.
Keywords: Endocrine disrupting compounds (EDCs), Gonad histology, Haematology, Petroleuciscus esfahani, Vitellogenin expression