INFLUENCE OF VARIATION IN METHODOLOGY ON THE RELIABILITY OF THE ISOELECTRIC-FOCUSING METHOD OF FISH SPECIES IDENTIFICATION

The reliability of isoelectric focusing (IEF) of sarcoplasmic proteins for fish species identification was evaluated by a collaborative stud y among eight European laboratories. Each laboratory used its own meth od of IEF to identify 10 unknown samples of raw muscle by means of ref erence material. In 93% of cases the assignment between sample and ref erence was correct. In a second study, the influence of extractant (wa ter, low ionic strength buffer, or detergent) and the position of samp le application on the protein pattern was examined, Working with light muscle of rainbow trout (Oncorhynchus mykiss), it was found that the type of extractant did not influence the protein pattern. Comparison o f the patterns of samples, which had been applied near the anode, in t he middle, or near the cathode, revealed differences in the number and position of the protein bands under the experimental conditions appli ed by most laboratories. This effect was not observed with the Phast S ystem.