PURIFICATION OF THE 70-KDA HEAT-SHOCK PROTEIN FROM CATFISH LIVER - IMMUNOLOGICAL COMPARISON OF THE PROTEIN IN DIFFERENT FISH SPECIES AND ITS POTENTIAL USE AS A STRESS INDICATOR

The heat-shock protein or stress-70 family was isolated from catfish l iver. The homogeneity of the purified protein was analyzed by sodium d odecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Fish sub jected to whole-body hyperthermia contained the constitutive and the h eat-inducible stress-70 with approximate molecular weights of 70 and 6 8 kDa, respectively. The final purification product from livers of cat fish raised under normal temperature was only the constitutive stress- 70. Western blot analysis with rabbit antiserum prepared against purif ied catfish (Ictalurus punctatus) liver stress-70 showed that the anti body cross-reacted with liver, muscle, and gill tissue homogenates of fathead minnows (Pimephales promelas), red shiners (Cyprinella lutrens is), black bass (Micropterus salmoides), and bluegill (Lepomis macroch irus), with various intensities suggesting that stress-70s from differ ent tissues of various fish species share common antigenic determinant s of the protein. This substantiates that the antigen/antibody approac h of stress-70 is useful as a stress indicator and, consequently, as a potential biomarker for water quality.