Investigation on Polymorphism of mitochondrial genome in Cobia fish Rachycentron canadum in the northern waters of the Persian Gulf and Oman Sea

Given the nutritious value of Cobia and its importance in terms of rapid growth in cultural conditions and noticeable commercial value, along with lack of sufficient literature in this regard, this study was run to investigate genomic polymorphism of this species in southern waters of Iran in 2010. The study aimed at enlightening genetic variation and determining its rate inside and between probable populations. This cross sectional study was carried out on 120 specimens of Cobia which were randomly obtained from four southern Iranian provinces. Two-gram cuts of fin tissue of each fish were transferred to the laboratory in 2 ml microtubes containing ethanol. DNA was extracted by Phenol-chlorophorm method and genomic polymorphism investigation was carried out by PCR-RFLP method. In this method, PCR product of COI mitochondrial gene were enzymatic digested using 6 Restriction Enzymes. PCR product of mitochondrial gene COI was obtained in length of 1060 base pair and 6 polymoiphic sites were investigated. But electrophoresis patterns of enzymatic digestion products were monomorphous in all samples and no polymorphism was observed. Lack of genetic diversity or its noticeable decrease in regions where fish can freely migrate and move between two regions has been reported. Due to lack of physical and biological obstacles Dobia is able to migrate to all parts of the Persian Gulf and Oman Sea. Therefore, lack of polymorphism in the studied Cobia population seems to be logical. Future studies with larger samples and more enzymes from other genetic regions are recommended.