Fig. 6. The effect of 1 h exposure of Callinectes to severe hypoxia (0.5% O₂) upon crustacean cardioactive peptide (CCAP) and arginine kinase (AK) expression in eyestalk tissues (A) and the thoracic ganglion (B), expressed as copy no. per eyestalk and per ganglion, respectively. Open bars indicate expression levels at t=0, filled bars at t=1 h (N=6). Error bars indicate +1 s.e.m. Asterisk indicates significant (P<0.05, Students t-test) reduction of mean CCAP levels after exposure to hypoxic conditions.