Species identification and PCR-RFLP analysis of cytochrome b gene in cod fish (Order Gadiformes) products

Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) profiles using the PCR product tRNA(Glu)-cytochrome b of 9 standard cod fish, all of which are imported into Japan under the name "cod fish," were investigated as a means of rapid species identification of imported cod fish products. Endonuclease digestion using 4 restriction enzymes (Alu I, Fok I, Mbo I, and Mse I) generated different digestion patterns for the standards, enabling species identification in imported cod fish products by comparison to the standards' RFLP profiles. Additionally, we conducted a more strict check by phylogenetic analysis on imported cod fish products with 13 standards (including 4 additional cod species from GenBank) using the mitochondrial cytochrome b gene (385 nt). Consequently, it was found that the PCR-RFLP method was sufficient for rapidly screening cod products, and in cases that require conclusive identification, phylogenetic analysis was the most suitable.