Putative involvement of adrenergic receptors in regulation of mussel (Perna canaliculus) larval settlement

Abstract

Settlement responses were investigated for mussel (Perna canaliculus) larvae after exposure to catecholamines and their precursor metabolites. Settlement and mortality assays were conducted in Petri plates with chemical treatments (L-phenylalanine, L-tyrosine, L-DOPA, dopamine hydrochloride and epinephrine at various concentrations) and controls. The proteinogenic amino acids L-phenylalanine and L-tyrosine were both effective inducers (~65%) of larval settlement at 10⁻⁵ mol l⁻¹ compared with controls (4%). Exposure of larvae to L-DOPA, dopamine and epinephrine resulted in maximum settlement induction (50, 60 and 51%, respectively) at 10⁻⁵ mol l⁻¹. Larval mortalities were low (comparable to controls) across all concentrations of L-phenylalanine and L-tyrosine treatments, whereas high mortalities (>60%) were observed for L-DOPA, dopamine and epinephrine at concentrations ≥ 10⁻⁴ mol l⁻¹. Our results indicate that P. canaliculus larval settlement is under endogenous regulation by a catecholaminergic mechanism. Furthermore, the inductive effects of all tested metabolites in the epinephrine biosynthesis pathway point to a putative involvement of adrenergic-type receptors in the regulation of larval settlement in this mussel species.

Key words:

• Catecholamines
• dopamine
• epinephrine
• green-lipped mussels
• larval settlement
• Perna canaliculus

Acknowledgements

We are thankful to Dan McCall (SPATnz) and Bridget Alexander (Cawthron Institute) for providing mussel larvae for these experiments. We are grateful to the laboratory technicians in the School of Applied Sciences, Auckland University of Technology, for their ongoing assistance. We also thank Annapoorna M. Ganesan, John Brooks, Colleen Higgins, and the rest of the Aquaculture Biotechnology Group at AUT for many fruitful discussions.

Editorial responsibility: Eric Thompson

Additional information

Funding

This research was supported by a Foundation for Research Science and Technology Pre-Seed grant (FRST-PSAF UOWX0716) and an AUT Research Grant to A. C. Alfaro.