Fig. 4. Effects of N-acetylneuraminic acid (NANA) and Mg-ASW on tentacle ectodermal cAMP content. Following 72h of starvation, one group of four anemones was pre-incubated in artificial sea water (ASW) containing 10^-4moll^-1 IBMX for 10min followed by incubation in ASW containing either 10^-4moll^-1 IBMX and 1.8x10^-5moll^-1 NANA (filled columns) or 10^-4moll^-1 IBMX alone (open columns) for 15min. Individual tentacles from each group were collected, snap-frozen, extracted and assayed for ectodermal cAMP using 1moll^-1 formic acid. Data are expressed as fmolcAMPµg^-1protein. A second, similar group of four anemones was treated as above except that Mg-ASW replaced ASW. Values are means ± S.E.M. (n=20 samples).