Identification of flatfish (Pleuronectiforme) species using DNA-based techniques

Identification of flatfish species using a DNA-based methodology was studie d. The polymerase chain reaction was employed to obtain a 464 bp amplicon f rom mitochondrial cytochrome b gene. The sequences from this fragment belon ging to 24 species were analyzed using a genetic distance method, and polym orphic sites were determined. The fragment was found to be highly polymorph ic (231 sites), and this permitted the differentiation of most of the speci es. Phylogenetic tree construction was employed to allow the identification of flatfish species. As a result, each species was grouped in a well-diffe rentiated clade, except for two pairs: Limanda ferruginea and L. limanda, a nd Solea impar and S. lascaris, which could not be differentiated. On the b asis of the sequences obtained, restriction enzymes were selected to provid e, specific restriction profiles, which allow the differentiation of 21 spe cies of flatfish in a faster and less expensive manner than sequencing. Thi s polymerase chain reaction-restriction fragment length polymorphism method ology (PCR-RFLP) was tested using commercial samples.