Fig. 2. mRNA levels of (A) citrate synthase and (B) cytochrome c oxidase subunit 2 in the liver of G. morhua from North Sea (NSC) and Barents Sea (NEAC), respectively, acclimated to 4°C and 10°C. The relative quantities of CISY and COX2 were determined from ribonuclease protection assays. Data were corrected for loading differences using the 18S rRNA signal. Values are means ± s.e.m. (N=5–6) and expressed relative to the warm-acclimated control group (NSC, 10°C), which was set to 1. The data were tested for outliers at the 95% significance level using Nalimov's test (Noack, 1980). *Significant difference from the warm-acclimated control group within a population; *significant difference between populations at the same acclimation temperature.