FISHERY BULLETIN: VOL. 75, NO. 3 



h S 

 CvJ 



i, 



"U 



42 



54 



18 24 30 36 



DISTANCE TO CATHODE (mm) 



60 



66 



FIGURE 5. — Reproducibility of pH gradients. Measurements of 

 pH were taken after focusing the gels shown in Figures 3 and 4. 

 The pH gradient A corresponds to the pH measurements taken 

 from the gel in Figure 3. The pH gradient B corresponds to the 

 pH measurements taken from the gel in Figure 4. (The pH 

 gradients do not match exactly because the platinum electrodes 

 were not placed with the same relative sample well to cathode 

 distance. The only effect this has on the protein patterns is to 

 shift them either up or down. Relative distances between the 

 various proteins in the pattern remain essentially the same.) 

 The similarity of these two pH gradients may be correlated with 

 the reproducibility of the protein banding patterns shown in 

 Figures 3 and 4. 



power supply should produce high quality sarco- 

 plasmic protein patterns in 1.0-1.5 h. New protein 

 staining methods have been investigated that 

 allow staining of the protein patterns in 15-30 

 min with no destaining required. Using these im- 

 provements, samples may be identified in less 

 than 2 h. 



CONCLUSIONS 



Thin-layer polyacrylamide gel isoelectric focus- 

 ing has been shown to be a promising technique 

 for the identification offish species. The inherent 

 high resolution of this method allows the produc- 

 tion of characteristic protein patterns of a quality 

 not normally attained by conventional electro- 

 phoretic techniques. The excellent reproducibility 

 of this technique should allow the positive identi- 

 fication of fish species without maintaining a 

 supply of known species for use as standards. 



Investigations utilizing commercially prepared 

 gel slabs, high-voltage constant-power power 

 supplies, and rapid staining techniques promise 

 to produce an extremely reliable procedure for 

 the routine identification of fish species. 



ACKNOWLEDGMENT 



I thank James Drysdale and Wendy Otavsky 

 of Tufts University Medical School, Boston, Mass., 

 for their valuable assistance in the early stages 

 of this work. 



LITERATURE CITED 



CONNELL, J. J. 



1953. Studies on the proteins of fish skeletal muscle. 

 Electrophoretic analysis of low ionic strength extracts of 

 several species of fish. Biochem. J. 55:378-388. 



COWIE, W. P. 



1968. Identification offish species by thin-slab polyacryla- 

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 Food Agric. 19:226-229. 



HILL, W. S., R. J. LEARSON, AND J. P. LANE. 



1966. Identification of fish species by agar gel electro- 

 phoresis. J. Assoc. Off. Anal. Chem. 49:1245-1247. 



Lane, j. P., W. S. Hill, and R. J. Learson. 



1966. Identification of species in raw processed fishery 

 products by means of cellulose polyacetate strip electro- 

 phoresis. Commer. Fish. Rev. 28(3):10-13. 



Learson, R. J. 



1969. Collaborative study of a rapid electrophoretic 

 method for fish species identification. J. Assoc. Off. 

 Anal. Chem. 52:703-707. 



1970. Collaborative study of a rapid electrophoretic 

 method for fish species identification. II. Authentic fish 

 standards. J. Assoc. Off. Anal. Chem. 53:7-9. 



Payne, W. R., Jr. 



1963. Protein typing of fish, pork, and beef by disc 

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 1005. 

 RIGHETTI, P. G., AND J. W. DRYSDALE. 



1974. Isoelectric focusing in gels. J. Chromatogr. 98: 

 271-321. 

 THOMPSON, R. R. 



1960. Species identification by starch gel zone electro- 

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1967. Disk electrophoresis method for the identification of 

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