Investigations on the biotransformation capacity of organophosphates in the mollusc Dreissena polymorpha P

Microsomes of Dreissena polymorpha were able to biotransform the organophosphates thiometon and disulfoton significantly after 1 h incubation at 10 degrees C. Contrarily to vertebrates, biotransformation with mussel microsomes occurred without the addition of reduction equivalents (NADPH), at a considerably lower extent however. Metabolites of thiometon and disulfoton were detected with gas chromatography/mass spectrometry (GC/MS) analysis: The P450 content of whole mussel tissue was 8 pmol mg(-1) protein being two orders of magnitude lower than the amounts measured in mammal liver. Ethoxycoumarin deethylase (ECOD) activity could be measured at 10 degrees C in microsomes of Dreissena (22 pmol min(-1) mg(-1) protein) but not at 37 degrees C. ECOD activity was inhibited in the presence of NADPH (measured activity 3 pmol min(-1) mg(-1)).