A comparison of the heat shock response in juvenile and adult rainbow trout (Oncorhynchus mykiss) - implications for increased thermal sensitivity with age

We conclude that the heat shock response is enhanced in juvenile compared with adult rainbow trout, Oncorhynchus mykiss. We have shown that the magnitude of the inducible heat shock response, as measured by increases in the heat shock protein (Hsp) Hsp70 is significantly greater in the hearts of fingerling than in adult trout following an acute (1 h) heat stress at 25 degrees C. Juvenile fish also express higher levels of constitutive Hsps (Hsc70, Hsp90) in their tissues, possibly reflecting higher rates of protein synthesis and increased chaperone function in this early life stage. This robust heat shock response in juvenile trout may contribute to a greater thermal resistance that is often observed in young salmonid fish.