a validated methodology for genetic identification of tuna species (genus thunnus)金枪鱼物种的基因识别的验证方法(属鳍).pdfVIP

A Validated Methodology for Genetic Identification of Tuna Species (Genus Thunnus) ˜ 1 2 Jordi Vinas *, Sergi Tudela ` 1 Laboratori d’Ictiologia Genetica, Departament de Biologia, Universitat de Girona, Girona, Spain, 2 World Wide Fund for Nature, Mediterranean Programme Office, Barcelona, Spain Abstract Background: Tuna species of the genus Thunnus, such as the bluefin tunas, are some of the most important and yet most endangered trade fish in the world. Identification of these species in traded forms, however, may be difficult depending on the presentation of the products, which may hamper conservation efforts on trade control. In this paper, we validated a genetic methodology that can fully distinguish between the eight Thunnus species from any kind of processed tissue. Methodology: After testing several genetic markers, a complete discrimination of the eight tuna species was achieved using Forensically Informative Nucleotide Sequencing based primarily on the sequence variability of the hypervariable genetic marker mitochondrial DNA control region (mtDNA CR), followed, in some specific cases, by a second validation by a nuclear marker rDNA first internal transcribed spacer (ITS1). This methodology was able to distinguish all tuna species, including those belonging to the subgenus Neothunnus that are very closely related, and in consequence can not be differentiated with other genetic markers of lower variability. This methodology also took into consideration the presence of introgression that has been reported in past studies between T. thynnus, T. orientalis and T. alalunga. Finally, we applied the methodology to cross-check the species identity of 26 processed tuna samples. Conclusions: Using the combination of two genetic markers, one