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

Abstract

AbstractThe heat‐shock protein or stress‐70 family was isolated from catfish liver. The homogeneity of the purified protein was analyzed by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE). Fish subjected to whole‐body hyperthermia contained the constitutive and the heat‐inducible stress‐70 with approximate molecular weights of 70 and 68 kDa, respectively. The final purification product from livers of catfish raised under normal temperature was only the constitutive stress‐70. Western blot analysis with rabbit antiserum prepared against purified catfish (Ictalurus punctatus) liver stress‐70 showed that the antibody cross‐reacted with liver, muscle, and gill tissue homogenates of fathead minnows (Pimephales promelas), red shiners (Cyprinella lutrensis), black bass (Micropterus salmoides), and bluegill (Lepomis macrochirus), with various intensities suggesting that stress‐70s from different tissues of various fish species share common antigenic determinants of the protein. This substantiates that the antigen/antibody approach of stress‐70 is useful as a stress indicator and, consequently, as a potential biomarker for water quality.