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(181) A comparison of pyrene biotransformation in three species of terrestrial invertebrate (Collembola and Isopoda). Howsam, Mike1, Jack, Emma1, Stroomberg, Gerard2, van Gestel, Cornelius1, van Straalen, Nico1, 1 2 ABSTRACT- Terrestrial invertebrates have been shown to be efficient at metabolising polycyclic aromatic hydrocarbons (PAHs) in a range of studies. Metabolism of pyrene by the isopod Porcellio scaber has been shown to proceed via an initial cytochrome P450-induced hxdroxylation of the parent PAH to 1-hydroxypyrene (Stroomberg et al., 1996, Chemosphere 33, 1905). A secondary phase of the metabolism has been described in P. scaber and Oniscus asellus (Isopoda) by De Knecht et al. (Environ. Toxicol. Chem., in press), and consists of enzymatic conjugation of the hydroxypyrene to more readily excreted compounds. Two of the four conjugates found in P. scaber have been formally identified as pyrene-1-sulfate and pyrene-1-glucoside by Stroomberg and co-workers, and the elimination kinetics of pyrene and its metabolites in this isopod described (Stroomberg et al., 1999, Environ. Toxicol. Chem., 18, 2217; Stroomberg et al., Environ. Toxicol. Chem., submitted). Unpublished data from Jack indicate that the collembolan Folsomia candida produces only two of the three main 1-hydroxypyrene conjugates seen in P. scaber, the metabolite 'profile' from the insect lacking the pyrene-1-sulfate conjugate seen in the isopod. The significance of this difference remains unknown, but our recent work with Orchesella cincta (Collembola) provides the opportunity to compare its pyrene metabolism with that of P. scaber and F. candida. We aim to describe the mixture toxicity of pyrene and cadmium in O. cincta during this project, but our initial results will be presented in the light of previous work on pyrene metabolism in terrestrial invertebrates. Key words: pyrene, metabolism, isopoda, collembola |
