USE OF MTDNA DIRECT POLYMERASE-CHAIN-REACTION (PCR) SEQUENCING AND PCR-RESTRICTION FRAGMENT LENGTH POLYMORPHISM METHODOLOGIES IN SPECIES IDENTIFICATION OF CANNED TUNA

Identification of six canned tuna species using DNA-based methodology was studied. DNA was degraded during the canning process of fish muscl e: DNA fragment sizes that ranged from <100 up to 200 bp were obtained from canned tuna muscle, whereas DNA sizes for frozen tuna muscle ran ged from <100 up to 20 000 bp. Amplification of DNA from canned tuna m uscle was carried out using primers flanking a region of cytochrome b gene of 126 bp. Sequences from PCR-amplified DNA of six tuna species w ere studied for polymorphic sites; seven diagnostic positions were ide ntified in this fragment for the species studied. The suitability of a genetic distance measurement with phylogenetic tree construction meth od for the identification of canned tuna species using two cytochrome b sequences (299 and 126 bp) was studied. PCR-amplified DNA from canne d tuna was also analyzed by using three restriction endonucleases, Bsi YI, MboI, and MnlI. The restriction fragments allowed for the identifi cation of the six tuna species studied.