Meeting Abstract

P2.49  Monday, Jan. 5  Regulation of Metamorphosis by Catecholamines in Larvae of the Polychaete Capitella sp. I LANGSTON, Jennifer; PIRES, Anthony*; Dickinson College; Dickinson College pires@dickinson.edu

Recent work has indicated that catecholamines regulate the induction of metamorphosis in primitive and derived gastropods. We have begun to investigate the distribution of this developmental control mechanism in other lophotrochozoan taxa, by studying the effects of endogenous catecholamines on metamorphosis of the polychaete, Capitella sp. I. Immunolabeling for the catecholamine-generating enzyme, tyrosine hydroxylase (TH), revealed TH-immunopositive cells in apical regions of the prostomium, in the circumesophageal nerve ring, underlying the prototroch and columns of setae, and in the pygidium. Catecholamine biosynthesis was depressed by the TH inhibitor, α-methyl-DL-m-tyrosine (α-MMT) and enhanced by the catecholamine precursor, L-DOPA. To verify effects of these drugs, norepinephrine and dopamine were quantified by high pressure liquid chromatography. Endogenous dopamine was depleted by α-MMT and enhanced by L-DOPA; norepinephrine was depleted by α-MMT but was unaffected by L-DOPA. After drug treatments, metamorphosis was assayed in response to a natural cue (an extract of sediment from adult habitat). Frequency of metamorphosis after 48 h was significantly lower in larvae treated with α-MMT and in larvae treated with L-DOPA, than in artificial seawater controls. Therefore, consistent with studies in several gastropod species, depletion of endogenous catecholamines inhibited metamorphosis of Capitella sp. I. Enhancement of endogenous catecholamines by L-DOPA failed to potentiate metamorphosis in this study, consistent with earlier findings in a patellogastropod, but unlike results obtained in more derived gastropods. The possible origins of modulation of metamorphosis by catecholamines are discussed.