Three eel species such as Anguilla japonica (AJ), Muraenesox cinereus (MC) and Conger myriaster (CM), belonging to the order Anguilliformes, are the most popular marine products in Korea because of their taste and nutritional value, and Koreans consume them in large quantities. Eel, ecologically important warm water fish species widely distributed on the coast of the Yellow Sea, southern sea and the several sea areas under the natural ecosystem. However, in spite of their economic and scientific consequences, a little information currently exists regarding the genetic levels only of eel species in Korea. In this study, to explicate the genetic distances and differences among geographical eel species, the author accomplished a clustering analysis of three eel species collected from the Yellow Sea. PCR analysis was performed on DNA samples extracted from a total of 21 individuals using seven oligonucleotides primers. Muscle tissues were obtained separately from individuals from Anguilla japonica, Muraenesox cinereus and Conger myriaster, respectively. Eel muscle was collected in sterile tubes, instantaneously placed in liquid nitrogen, and stored at －40℃ until the genomic DNA extraction. Genomic DNA was extracted and purified under the conditions described previously (Yoon, 2008). After several washings, lysis bufferⅠ (155 mM NH4Cl; 10 mM KHCO3; 1 mM EDTA) was added to the samples, and the mixture tubes were gently inverted. The concentration of the extracted genomic DNA was measured by optical density at 260 nm by a spectrophotometer (Beckman Coulter, Buckinghamshire, UK). PCR was performed using two Programmable DNA Thermal Cyclers (MJ Research Inc., Waltham, MA, USA). Euclidean genetic distances within- and between-species were also calculated using the hierarchical dendrogram program Systatver.10 (SPSSInc., Chicago, IL, USA). Seven oligonucleotides primers were shown to generate the shared loci, specific loci, unique shared loci to each species and shared loci by the three species which could be obviously scored. In the present study, 7 oligonucleotides primers generated 191 specific loci in the AJ species, 226 in the MC species and 181 in the CM species, respectively. The specific loci generated by oligonucleotides primers exhibited inter-individual-specific characteristics, thus revealing DNA polymorphisms. The gDNA isolated from three eel species were amplified by PCR. Here, the seven oligonucleotide primers were used to generate the unique shared loci to each species and shared loci by the three eel species. With regard to average bandsharing value (BS) results, individuals from Conger myriaster species (0.808) exhibited higher bandsharing values than did individuals from Muraenesox cinereus species (0.729) (P<0.05). The dendrogram resulted from reliable seven oligonucleotides primers, indicating three genetic clusters composed of group I, group II and group III. The longest genetic distance (0.430) displaying significant molecular difference was also between individual no. 01 within Anguilla japonica eel species and individual no. 04 within Anguilla japonica species. From what has been said above, the potential of this analysis to ascertain diagnostic markers for the identification of three eel species has also been verified (McCormack et al., 2000; Yoon, 2008).

• Jong-Man Yoon(Department of Aquatic Life Medicine, College of Ocean Science and Technology, Kunsan National University)