Pyrene metabolism in the springtailOrchesella cinctaL. (Collembola, Entomobryidae)

Abstract

A novel, solvent-free spiking method was used to contaminate foodstuff (Desmococcus spp. algae) with pyrene for bioassays with the springtail Orchesella cincta L. (Collembola, Entomobryidae). The primary metabolite 1-hydroxypyrene and two conjugates (pyrene-1-glucoside and one tentatively identified as pyrene-1-glucosidemalonate) were quantified in the insects by high-performance liquid chromatography (HPLC) with fluorescence detection. Individuals from an unpolluted site (SUS population) were capable of rapid metabolism of pyrene, reaching an apparent steady state after 24 h with a composite assimilation/transformation rate of approximately 25 pmol pyrene x g(-1) fresh weight x h(-1) at an exposure level of approximately 18 microg pyrene x g(-1) dry weight algae. A cadmium (Cd)-tolerant population (TOL), genetically distinct from SUS, was exposed in parallel and the populations' pyrene metabolism compared in order to gain insight into any potential cost of Cd-tolerance. The TOL animals assimilated and/or performed phase 1 transformation of pyrene approximately twice as fast as SUS (approximately 56 pmol x g(-1) x h(-1)), but there was no significant difference in the elimination rate constants between SUS and TOL animals. Attributing this difference to any specific cost of Cd-tolerance requires more work and may he coincidental to metal tolerance, but pyrene metabolism in these distinct genotypes, subjected to different selection pressures, was nevertheless significantly different.