Fig. 4. (A) Plasma cortisol levels in carp acclimated for 8 weeks to water temperatures of 15, 22 or 29°C and in 22°C-acclimated carp that had a minipump filled with vehicle or cortisol implanted for 7 days. (B) Pituitary prolactin expression, relative to the housekeeping gene ß-actin, in 15, 22 or 29°C-acclimated carp quantified by real-time PCR. Values are means ± S.E.M. Asterisks indicate statistically significant differences among groups (*P<0.05; **P<0.01).