title: Induction of multixenobiotic defense mechanisms in resistant Daphnia magna clones as a general cellular response to stress.
abstract: Multixenobiotic resistance mechanisms (MXR) were recently identified in Daphnia magna. Previous results characterized gene transcripts of genes encoding and efflux activities of four putative ABCB1 and ABCC transporters that were chemically induced but showed low specificity against model transporter substrates and inhibitors, thus preventing us from distinguishing between activities of different efflux transporter types. In this study we report on the specificity of induction of ABC transporters and of the stress protein hsp70 in clones selected to be genetically resistant to ABCB1 chemical substrates. Clones resistant to mitoxantrone, ivermectin and pentachlorophenol showed distinctive transcriptional responses of transporter protein coding genes and of putative transporter dye activities. Expression of hsp70 proteins also varied across resistant clones. Clones resistant to mitoxantrone and pentachlorophenol showed high constitutive levels of hsp70. Transcriptional levels of the abcb1 gene transporter and of putative dye transporter activity were also induced to a greater extent in the pentachlorophenol resistant clone. Observed higher dye transporter activities in individuals from clones resistant to mitoxantrone and ivermectin were unrelated with transcriptional levels of the studied four abcc and abcb1 transporter genes. These findings suggest that Abcb1 induction in D. magna may be a part of a general cellular stress response.
authors.affiliation: Department of Environmental Chemistry, Institute of Environmental Assessment and Water Research (IDAEA), Spanish Research Council (IDAEA, CSIC), Barcelona, Spain; Centre for Environmental and Marine studies (CESAM), Department of Biology, University of Aveiro, Aveiro, Portugal; MARE-Marine and Environmental Sciences Centre, ESTM, Polytechnic Institute of Leiria, Peniche, Portugal.
authors.forename: Rita
authors.initials: R
authors.lastname: Jordão
authors.affiliation: Department of Environmental Chemistry, Institute of Environmental Assessment and Water Research (IDAEA), Spanish Research Council (IDAEA, CSIC), Barcelona, Spain.
authors.forename: Bruno
authors.initials: B
authors.lastname: Campos
authors.affiliation: MARE-Marine and Environmental Sciences Centre, ESTM, Polytechnic Institute of Leiria, Peniche, Portugal.
authors.forename: Marco F L
authors.initials: MF
authors.lastname: Lemos
authors.affiliation: Centre for Environmental and Marine studies (CESAM), Department of Biology, University of Aveiro, Aveiro, Portugal.
authors.forename: Amadeu M V M
authors.initials: AM
authors.lastname: Soares
authors.affiliation: Department of Environmental Chemistry, Institute of Environmental Assessment and Water Research (IDAEA), Spanish Research Council (IDAEA, CSIC), Barcelona, Spain.
authors.forename: Romà
authors.initials: R
authors.lastname: Tauler
authors.affiliation: Department of Environmental Chemistry, Institute of Environmental Assessment and Water Research (IDAEA), Spanish Research Council (IDAEA, CSIC), Barcelona, Spain. Electronic address: cbmqam@cid.csic.es.
authors.forename: Carlos
authors.initials: C
authors.lastname: Barata
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B / Q000235:genetics / Q000378:metabolism; D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001692:Biological Transport / Q000235:genetics; D003621:Daphnia / Q000187:drug effects* / Q000235:genetics; D005786:Gene Expression Regulation / Q000187:drug effects*; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D013312:Stress, Physiological / Q000187:drug effects*; D014874:Water Pollutants, Chemical / Q000633:toxicity
chemical_list: D018435:ATP Binding Cassette Transporter, Subfamily B; D018528:ATP-Binding Cassette Transporters; D018840:HSP70 Heat-Shock Proteins; D014874:Water Pollutants, Chemical
keywords: Daphnia magna; Hsp70; Induction; MDR; P-glycoprotein