Substitution of fish species detected by thin-layer isoelectric focusing and a computer-assisted method for the evaluation of gels.

Fourteen fish species susceptible to substitution were analysed by the thin-layer isoelectric focusing technique on polyacrylamide gels of pH 3.5-9.5. Four fish per species were run on the same gel to verify the possibility to differentiate them according to their protein banding patterns. The occurrence of intraspecific differences due either to electrophoretic variations or to protein polymorphism was also observed. In fact, some of them showed few dissimilarities among their protein profiles. However, the differentiation was possible for all species, even for those belonging to the same order, family and genus. Computer-based tools combined with statistical analysis were implemented and usefully applied to avoid a subjective evaluation of the isoelectric focusing gels, and to verify the reliability of the preliminary visual comparison of protein patterns.