A study on phosphoglucose isomerase enzyme in some elasmobranch fishes collected from Khor Al-Zubair, north west of the Arabian Gulf, Iraq.

Tissue extracts of skeletal muscle, brain, gills, liver, kidney, heart, eye and spleen were electrophoretically examined for phosphoglucose isomerase (EC 5.3.1.9) activity in five species of elasmobranch fishes. Two phosphoglucose isomerases (PGI) with different specification have been found in all groups of elasmobranch fishes studied. PGI proved to be a good taxonomic criterion to differentiate members of the families Sphyrindae and Dasyatidae from the other remaining elasmobranch families. PGI appears to be controlled by duplicated genes as in other teleostean fishes.