title: Changes in Lumbriculus variegatus metabolites under hypoxic exposure to benzo(a)pyrene, chlorpyrifos and pentachlorophenol: consequences on biotransformation.
abstract: The regulation of endogenous metabolites is still not fully understood in aquatic invertebrates exposed concurrently to toxicants and hypoxia. Despite the prevalence of hypoxia in the aquatic environment, toxicity estimations seldom account for multiple stressors thereby differing from natural conditions. In this study, we examined the influence of hypoxia (<30% O2) on contaminant uptake and the composition of intracellular metabolites in Lumbriculus variegatus exposed to benzo(a)pyrene (B(a)P, 3μgL(-1)), chlorpyrifos (CPF, 100μgL(-1)) or pentachlorophenol (PCP, 100μgL(-1)). Tissue extracts of worms were analyzed for 123 metabolites by gas chromatography-mass spectrometry and metabolite levels were then related to treatments and exposure time. Hypoxia markedly increased the accumulation of B(a)P and CPF, which underlines the significance of oxygen in chemical uptake. The oxygen effect on PCP uptake was less pronounced. Succinate and glycerol-3-phosphate increased significantly (p<0.0001) following hypoxic treatment, whereas sugars, cysteine, and cholesterol were effectively repressed. The buildup of succinate coupled with the corresponding decline in intracellular 2-oxo- and 2-hydroxy glutaric acid is indicative of an active hypoxia inducible factor mechanism. Glutamate, and TCA cycle intermediates (fumarate, and malate) were disturbed and evident in their marked suppression in worms exposed concurrently to hypoxia and PCP. Clearly, hypoxia was the dominant stressor for individuals exposed to B(a)P or CPF, but to a lesser extent upon PCP treatment. And since oxygen deprivation promotes the accumulation of different toxicants, there may be consequences on species composition of metabolites in natural conditions.
authors.affiliation: Department of Biology, University of Eastern Finland, Yliopistokatu 7, P.O. Box 111, FI-80101 Joensuu, Finland. Stanley.Agbo@uef.fi
authors.forename: Stanley O
authors.initials: SO
authors.lastname: Agbo
authors.forename: Markku
authors.initials: M
authors.lastname: Keinänen
authors.forename: Sarita
authors.initials: S
authors.lastname: Keski-Saari
authors.forename: Juha
authors.initials: J
authors.lastname: Lemmetyinen
authors.forename: Jarkko
authors.initials: J
authors.lastname: Akkanen
authors.forename: Matti T
authors.initials: MT
authors.lastname: Leppänen
authors.forename: Philipp
authors.initials: P
authors.lastname: Mayer
authors.forename: Jussi V K
authors.initials: JV
authors.lastname: Kukkonen
mesh_terms: D000818:Animals; D001564:Benzo(a)pyrene / Q000378:metabolism / Q000633:toxicity; D001711:Biotransformation; D004390:Chlorpyrifos / Q000378:metabolism / Q000633:toxicity; D004785:Environmental Pollutants / Q000378:metabolism* / Q000633:toxicity*; D009835:Oligochaeta / Q000187:drug effects* / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D010416:Pentachlorophenol / Q000378:metabolism / Q000633:toxicity
chemical_list: D004785:Environmental Pollutants; D001564:Benzo(a)pyrene; D010416:Pentachlorophenol; D004390:Chlorpyrifos; D010100:Oxygen
keywords: Hypoxia; Lumbriculus variegatus; Metabolites; Multiple stressors; PCA; Toxicometabolomics