Résumé
The recent genome duplication in salmonids has led to the presence of two GH receptors (GHRs). As temperature is a determining factor in fish growth, this study aims to determine whether the growth-promoting effect of temperature may be related to a change in GHR gene expression in embryo and juvenile rainbow trout. During embryonic development, using real-time PCR, we showed that high temperatures (12 vs 4 degrees C) increased the amounts of GHR1 transcript up to the hatching stage. By contrast, whatever the stage examined, the levels of GHR2 mRNA were unaffected by the incubation temperature. Nevertheless, incubating eggs with GH led to an enhanced embryo weight only after hatching, suggesting that GHR was not able to mediate the growth-promoting effect of GH before hatching. For juveniles, the GH-binding capacities of fish liver reared at 8, 12 or 16 degrees C revealed that high temperatures led to a lower GH binding. To better understand whether temperature regulates