Identification of Fish Species by Thin Layer Isoelectric Focusing of Sarcoplasmic Protein

Abstract

The technique of comparisons of the thin layer isoelectric focusing patterns of sarcoplasmic protein was applied to identfication of fish species.
One gram of muscle tissue was blended with 2ml of 0.01M phosphate buffer, pH 7.0, and centrifuged at 12, 000rpm for 20min. The resulting supernatant was used for the sarcoplasmic protein pattern analysis. Isoelectric focusing was carried out on an LKB Multiphor apparatus using Ampholine PAG plate, pH 3.5-9.5 gradient.
Preliminary studies showed that the sarcoplasmic protein of a species of fish exhibits essentially the same pattern, irrespective of the body size, and any location of muscle which was taken from ordinary muscle. Frozen storage below -20°C for 42 months did not affect the pattern significantly.
Forty-one species of fish were analyzed for sarcoplasmic protein. The results obtained showed that the patterns are species-specific in many of the fishes tested, while the patterns are polymorphic in some fishes (such as black cow tongue Rhinoplagusia japonica, black sea bream Mylio macrocephalus, gizzard shad Konosirus punctatus, frigate mackerel Auxis tapeinosoma, carp Cyprinus capio and Tilapia nilotica). Even with those fishes, however, the identification of each species was possible, to some extent, by comparing some protein bands specific to each species. Rather exceptionally, the fishes belonging to the genus Thunnus or Tetrapturus showed patterns too similar to be distinguished from each other.