Meeting Abstract

P2.88  Wednesday, Jan. 5  Biochemical regulation of settlement and metamorphosis of larvae of Capitella teleta by serotonin RICKER, T.*; POESNECKER, R.; DEATS, S.; BIGGERS, W.J.; Wilkes University; Wilkes University; Wilkes University; Wilkes University william.biggers@wilkes.edu

The regulation of settlement and metamorphosis of several types of marine larvae into juveniles has been demonstrated to involve both stimulatory neurotransmitters, such as acetylcholine and serotonin, and also nitric oxide which acts as an inhibitory neurotransmitter that maintains the larval state. We have explored the involvement of serotonin in mediating settlement and metamorphosis of metatrochophore larvae of the polychaete annelid Capitella teleta. Previous results in our laboratory have indicated that exogenous serotonin can induce settlement and metamorphosis of these larvae and that ketanserin, a serotonin 5-HT2 receptor antagonist, inhibits the response of these larvae to both serotonin and also a natural chemical cue that induces settlement and metamorphosis. In further exploring regulation by serotonin, we now report that fluoxetine, a selective serotonin reuptake inhibitor, is able to also stimulate settlement and metamorphosis of these larvae, and that exogenous application of ketanserin also blocks the spontaneous settlement of these larvae that occurs in the absence of a natural chemical cue. We are also now carrying out experiments to determine if 5-HT2 receptors can be located within the larvae. These results provide further evidence that endogenous serotonin may regulate both induced and spontaneous settlement and metamorphosis in these larvae.