Cloning and characterization of a heat shock protein 70 gene from the yellowstripe goby, Mugilogobius chulae: Evidence for its significance in biomonitoring of environmental pollution

Heat shock protein 70 (HSP70), a molecular chaperone, is induced by heat shock and other stressors. In this study, a full-length HSP70 cDNA (McHSP70) from the Mugilogobius chulae (M. chulae), was characterized. It was found to contain a 211-bp 5′-untranslated region, a 273-bp 3′-untranslated region, and a 1920-bp open reading frame, which encoded a 639-amino-acid protein with a theoretical molecular weight of 70.24 kDa. Real-time polymerase chain reaction analysis revealed that McHSP70 was ubiquitously expressed in gills, muscle, bowel and liver, after heat shock treatment and Cu2+ exposure. On exposure to Cu2+, the bowel and gills showed significant expression compared to that in other organs where in McHSP70 immunoreactivity was observed. Immunohistochemical analysis confirmed that McHSP70 was localized mainly in the cell cytoplasm. These findings suggest that HSP70 has vital and conserved biological functions, indicating an important role of this protein as a marker for environmental pollution.