Fish species identification in canned tuna by PCR-SSCP: Validation by a collaborative study and investigation of intra-species variability of the DNA-patterns

Abstract

Analysis of single strand conformation polymorphism (SSCP) of an amplicon (123 bp) obtained by polymerase chain reaction (PCR) of the mitochondrial cytochrome b gene was used to identify the ®sh species in canned tuna. Single-stranded DNA (ssDNA) was separated by polyacrylamide gel electrophoresis, and visualised by silver staining. The reliability of the method was tested by a collaborative study in which eight European laboratories participated. Seven unknown samples (®ve from individual species and two mixtures of two tuna species) of canned tuna had to be identi®ed by comparison with reference material. From a total of 72 cases, 65 (90.3%) were assigned correctly. Intra-species variability of SSCIP patterns was found in the case of Katsuwonus pelamis and Sarda sarda. As specimens from various ®shing grounds gave two or three di erent patterns of ssDNA, the possibility of some variability of the DNA patterns has to be considered in SSCP analysis of these species