title: Use of a combined effect model approach for discriminating between ABCB1- and ABCC1-type efflux activities in native bivalve gill tissue.
abstract: Aquatic organisms, such as bivalves, employ ATP binding cassette (ABC) transporters for efflux of potentially toxic chemicals. Anthropogenic water contaminants can, as chemosensitizers, disrupt efflux transporter function enabling other, putatively toxic compounds to enter the organism. Applying rapid amplification of cDNA ends (RACE) PCR we identified complete cDNAs encoding ABCB1- and ABCC1-type transporter homologs from zebra mussel providing the molecular basis for expression of both transporter types in zebra mussel gills. Further, efflux activities of both transporter types in gills were indicated with dye accumulation assays where efflux of the dye calcein-am was sensitive to both ABCB1- (reversin 205, verapamil) and ABCC1- (MK571) type specific inhibitors. The assumption that different inhibitors targeted different efflux pump types was confirmed when comparing measured effects of binary inhibitor compound mixtures in dye accumulation assays with predictions from mixture effect models. Effects by the MK571/reversin 205 mixture corresponded better with independent action, whereas reversin 205/verapamil joint effects were better predicted by the concentration addition model indicating different and equal targets, respectively. The binary mixture approach was further applied to identify the efflux pump type targeted by environmentally relevant chemosensitizing compounds. Pentachlorophenol and musk ketone, which were selected after a pre-screen of twelve compounds that previously had been identified as chemosensitizers, showed mixture effects that corresponded better with concentration addition when combined with reversine 205 but with independent action predictions when combined with MK571 indicating targeting of an ABCB1-type efflux pump by these compounds.
authors.affiliation: Department of Environmental Chemistry, IDAEA-CSIC, Jordi Girona 18, 08034 Barcelona, Spain; CESAM & Departamento de Biologia, Universidade de Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: Melissa
authors.initials: M
authors.lastname: Faria
authors.affiliation: Siberian Institute of Plant Physiology and Biochemistry, Siberian Branch of Russian Academy of Sciences (SIPPB SB RAS), Lermontov Str. 132, 664033, Irkutsk, Russia; Department of Bioanalytical Ecotoxicology, UFZ - Helmholtz Centre for Environmental Research, Permoserstr. 15, D-04318 Leipzig, Germany.
authors.forename: Vasiliy
authors.initials: V
authors.lastname: Pavlichenko
authors.affiliation: Department of Bioanalytical Ecotoxicology, UFZ - Helmholtz Centre for Environmental Research, Permoserstr. 15, D-04318 Leipzig, Germany; Institute of Hydrobiology, Dresden University of Technology, D-01062 Dresden, Germany.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Burkhardt-Medicke
authors.affiliation: CESAM & Departamento de Biologia, Universidade de Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: Amadeu M V M
authors.initials: AM
authors.lastname: Soares
authors.affiliation: Department of Bioanalytical Ecotoxicology, UFZ - Helmholtz Centre for Environmental Research, Permoserstr. 15, D-04318 Leipzig, Germany.
authors.forename: Rolf
authors.initials: R
authors.lastname: Altenburger
authors.affiliation: Department of Environmental Chemistry, IDAEA-CSIC, Jordi Girona 18, 08034 Barcelona, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Barata
authors.affiliation: Department of Bioanalytical Ecotoxicology, UFZ - Helmholtz Centre for Environmental Research, Permoserstr. 15, D-04318 Leipzig, Germany. Electronic address: till.luckenbach@ufz.de.
authors.forename: Till
authors.initials: T
authors.lastname: Luckenbach
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001483:Base Sequence; D018076:DNA, Complementary / Q000235:genetics; D049875:Dreissena / Q000235:genetics / Q000378:metabolism*; D005880:Gills / Q000187:drug effects / Q000378:metabolism*; D008962:Models, Theoretical; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000494:pharmacology; D010802:Phylogeny; D011422:Propionates / Q000494:pharmacology; D011804:Quinolines / Q000494:pharmacology; D017422:Sequence Analysis, DNA; D014700:Verapamil / Q000494:pharmacology
chemical_list: D018528:ATP-Binding Cassette Transporters; D018076:DNA, Complementary; D009842:Oligopeptides; D011422:Propionates; D011804:Quinolines; C120261:reversin 205; C059141:verlukast; D014700:Verapamil
keywords: Dreissena polymorpha; Environment-tissue barrier; Mixture effect modeling; Multidrug resistance associated protein (MRP); Multixenobiotic resistance; P-glycoprotein