Figure 1:

Temperature profiles of the seven laboratory treatments (a) and effect of temperature on the gill heat shock protein-70 (HSP70; b), plasma cortisol (c) and glucose (d) in brook trout. Inset in (b) is a representative western blot. Water temperatures were elevated at a rate of 8°C h⁻¹ until target temperatures were achieved. Fish were sampled 6 h after initiation of heating. A piecewise regression using temperature as a predictor variable was used to determine temperature thresholds. The relationship between gill HSP70 abundance and temperature showed a threshold for induction of 20.7°C. The relationship between plasma glucose and temperature showed a threshold for induction of 21.2°C. Points represent means ± SEM (n = 6–8).