Heat shock protein (hsp70) in brown trout epidermis after sudden temperature rise.

So far, hsp70 has not yet been studied in the fish skin. This organ has a potential as an indicator organ and we investigate whether hsp70 could be used as a biomarker. In this study, we examined whether and how the epidermis reacts to a temperature rise. Brown trout, Salmo trutta fario, were exposed to higher temperature for 2 h and were allowed to recover subsequently. Samples were taken from controls, after heat shock, as well as after 24 and 48 h of recovery. The occurrence of hsp70 in trout skin was examined by Western blot. The amount of hsp70 was higher after 2-h heat shock and was rising until the end of the experiment. Immunocytochemically, hsp70 was detected in epidermal filament cells. After 2-h heat shock, hsp70 was predominantly located in the nucleus. At this time, light and electron microscopy revealed several features known to occur under a variety of stressors. Ultrastructurally, the appearance of compact filament aggregates in pavement cells was remarkable. After 24 h of recovery, filament compaction was lacking and after 48 h aspects of regeneration were obvious. However, an increased amount of apoptotic cells in the epidermis was prominent at this time only.