Fig. 1. RNA (A, white muscle; D, gill), protein (B, white muscle; E, gill) concentrations and RNA:protein ratios (C, white muscle; F, gill) in P. brachycephalum under control conditions (0°C; left, black bars), in warm-acclimated P. brachycephalum (5°C; left, grey bars), in cold-acclimated Z. viviparus (5°C; right, grey bars) and in control Z. viviparus (10°C; right, white bars). Values are means ± S.E.M. (N=6). Only the same tissues were tested for the significance of differences. Values with the same letter are significantly different. FM, fresh mass.