THE CHANGES OF NEUROTRANSMITTER CONTENT DURING METAMORPHOSIS OF BAY SCALLOP ARGOPECTEN IRRADIANS LARVAE

The changes of norepinephrine(NE),dopamine(DA)and 5 hydroxytryptamine(5 HT)in larvae of bay scallop Argopecten irradians at different development stages and after induced by KCl and CaCl 2 have been studied.The results show that NE levels in the corresponding larva and spat groups do not change significantly,with 2352(pg/mg WW)(before metamorphosis,13d)and 2770(pg/mg WW)(spats ). DA and 5 HT levels are low in young larvae,then increase with larvae developing.DA and 5 HT levels increase drastically just before metamorphosis(13d),which increase 2.8 and 4.7 times respectively compared to 12 day larvae.After metamorphosis,DA and 5 HT levels decrease drastically,which in spats following metamorphosis decrease 25.1 and 16.4 times respectively compared to 13 day larvae.The DA∶NE ratio and 5 HT∶NE ratio also change drastically among 12 day larvae,13 day larvae and spats.The DA∶NE ratio and 5 HT∶NE ratio increase drastically just before metamorphosis,which increase 3.0 and 5.0 times,respectively,and then decrease drastically after metamorphosis.The DA∶NE ratio and 5 HT∶NE ratio in spats decrease 29.8 and 19.5 times compared to 13 day larvae.The NE,DA and 5 HT levels and DA∶NE ratio,5 HT∶NE ratio decrease after induced by KCl and CaCl 2.The results suggest that DA and 5 HT maybe trigger the metamorphosis process of bay scallop A.irradians.