Pyrene Biotransformation and Kinetics in the Hepatopancreas of the Isopod Porcellio scaber

Abstract

Various techniques exist for polycyclic aromatic hydrocarbon (PAH) determination in environmental samples, but an adequate risk assessment of PAHs should include aspects such as bioavailability of the contaminant and biotransformation capacity of the species under investigation. In this study, we provided an analysis of the kinetics of pyrene in the terrestrial isopod Porcellio scaber. Isopods were exposed to pyrene in their food (10 microg/g d/w) for 7 days followed by an elimination period of 7 days. The animals were dissected, and the hepatopancreases were analyzed for pyrene biotransformation products; nonmetabolised pyrene in the gut was also monitored. Concentrations of 1-hydroxypyrene in the hepatopancreas were very low. Almost all of the pyrene was found as three conjugates: pyrene-1-glucoside, pyrene-1-sulfate, and a third unknown 1-hydroxypyrene conjugate. Concentrations of the metabolites were extremely variable between individuals because of variable feeding activity. An apparent steady state was reached already after 24 hours of exposure, whereas elimination was complete 48 hours after ending the exposure. This rapid response to changes in the exposure concentration shows that terrestrial isopods have a high biotransformation capacity for PAHs. The data show that concentrations of parent PAHs will not provide a good indication of exposure in rapidly metabolizing invertebrates such as isopods; instead, pyrene metabolites may be considered a promising biomarker for bioavailability of PAH contamination in the field.

Cadmium affects toxicokinetics of pyrene in the collembolan Folsomia candida

“…of sonication, 400 units of proteinase K solution was added and the sample was vortexed before being incubated at 38°C for 2 h. Ethanol amended with ascorbic acid was added and samples were centrifuged at 12,000 rpm, after which the debris were left in the Eppendorf tubes while liquid was transferred into brown HPLC vials. Supernatants were measured by HPLC applying an elution gradient as described by Stroomberg et al (2004) using the same equipment as mentioned for soil analysis and with fluorescence detection at λ ex/em  = 346/384 nm.…”

“…This model considers the animal as a homogeneous compartment with single uptake and elimination rates (e.g., Janssen et al 1991; Stroomberg et al 2004). The model parameters and corresponding standard errors were estimated by fitting the following equations simultaneously using non-linear regression in SPSS15.0:…”

Soil ecotoxicology: state of the art and future directions

“…The process of biotransformation aims at making chemicals more hydrophilic and in this way facilitating their excretion. Isopods and Collembola have been shown to be extremely efficient in biotransforming organic chemicals like Polycyclic Aromatic Hydrocarbons (PAHs), which are excreted by these organisms with half lives of approximately 1 day (Van Brummelen and Van Straalen 1996, Howsam and Van Straalen 2003, Stroomberg et al 2004). Earthworms seem less efficient in doing so.…”

Characterization of phase-II conjugation reaction of polycyclic aromatic hydrocarbons in fish species: Unique pyrene metabolism and species specificity observed in fish species

“…Moreover, several studies on biotransformation have already used pyrene as a model substance (Luthe et al, 2002;Akkanen and Kukkonen, 2003;Stroomberg et al, 2004;Ikenaka et al, 2006Ikenaka et al, , 2007Ueda et al, 2011). In this study, metabolites of pyrene excreted from fish in vivo and the kinetic parameters of pyrene metabolism in phase-I (CYP) and phase-II (UGT and SULT) reactions in vitro were profiled.…”