Preliminary investigation on cholinesterases activity in Adamussium colbecki from Terra Nova Bay: Field and laboratory study

Abstract

While the inhibition of cholinesterase (ChE) activity as a biomarker of exposure to neurotoxic insecticides is well established in aquatic invertebrates of temperate areas, little is known about organisms from polar regions including Antarctica. Cholinesterase activity was investigated in specimens of the Antarctic scallop, Adamussium colbecki, collected in winter 2000 at Campo Icaro (Ross Sea, Antarctica) for preliminary characterization of a potentially new biomarker. Characterization of various ChE enzymes using specific substrates including an acetylthiocholine iodide (ASCh) and a butyrylthiocholine iodide (BSCh) was performed in gills, digestive gland and adductor muscle of the scallop. The effect of in vivo Zn²⁺ exposure in gills and digestive gland of A. colbecki was also studied. All the tissues expressed ChE activity (gill > adductor muscle > digestive gland) in accordance with data reported for marine mussels (Mytilus sp.) from temperate areas (1.1–13.8 nmol min⁻¹ mg protein⁻¹). Significant BSCh-dependent ChE inhibition was also measured with a specific inhibitor, Iso-OMPA. Exposure to Zn²⁺ does not seem to affect ChE activity in the scallop although some slight differences were observed in substrate specificities (ASCh and BSCh) between treated and untreated organisms. This preliminary study stresses the need for further investigation on ChE activity in A. colbecki as a biomarker for monitoring water contamination in the marine Antarctic environment.

Keywords:

• Adamussium colbecki
• Antarctica
• Cholinesterase
• Biomarker
• ZnCl2

Acknowledgements

The present study was performed in the framework of the Italian National Programme for Antarctic Research (PNRA).