A Conventional Multiplex PCR Assay for the Detection of Toxic Gemfish Species (Ruvettus pretiosus and Lepidocybium flavobrunneum): A Simple Method to Combat Health Frauds

The meat of Ruvettus pretiosus and Lepidocybium flavobrunneum (gemfishes) contains high amounts of indigestible wax esters that provoke gastrointestinal disorders. Although some countries have banned the sale of these species, mislabeling cases have been reported in sushi catering. This work developed a simple conventional multiplex PCR, which discriminates the two toxic gemfishes from other potentially replaced species, such as tunas, cod, and sablefish. A common degenerate forward primer and three species-specific reverse primers were designed to amplify cytochrome oxidase subunit I (COI) gene regions of different lengths (479, 403, and 291 bp) of gemfishes, tunas, and sablefish, respectively. A primer pair was designed to amplify a fragment (193 bp) of the cytb gene of cod species. Furthermore, a primer pair targeting the 16S rRNA gene was intended as common positive control (115 bp). The method developed in this study, by producing the expected amplicon for all of the DNA samples tested (reference and commercial), provides a rapid and reliable response in identifying the two toxic species to combat health frauds.