Fig. 4. Up-regulation of D2 mRNA and enzyme activity after hypo-osmotic stress. (A) D2 enzymatic activity from the in vivo time-course experiment. The increase in D2 activity became significant only 12 h after the osmotic challenge. (B) A separate set of experiments showing mRNA concentrations (filled bars) and D2 activity (open bars). The increase in mRNA precedes the corresponding rise in D2 activity, and attained maximum values 8 h after osmotic stress. For each panel, values are means ± s.e.m. (N=10) of two separate experiments, each in triplicate. ^*P<0.05 vs control (C).