title: Metallothioneins (MTs) and delta-aminolevulinic acid dehydratase (ALAd) as biomarkers of metal pollution in great tits (Parus major) along a pollution gradient.
abstract: Biomonitoring allows an integrated evaluation of different aspects of exposure, accumulation and effects to environmental pollution, simultaneously accounting for the natural variety between individuals in an ecosystem. In this study, the effects of increased metal accumulation were evaluated at the biochemical level in terms of two biomarker responses in the great tit (Parus major), a small insectivorous songbird, along an established metal pollution gradient. Metal concentrations in internal tissues (liver and kidney) and blood indicated that lead and cadmium were the most important metals in the pollution gradient under study. At the biochemical level, induction of metal binding protein metallothionein (MT) in liver and kidney reflected cadmium concentrations in these tissues (R(2)=0.42 and R(2)=0.94 respectively, n=19), although in kidney, MT induction was not sufficient to complex all cadmium present. Secondly, the activity of the enzyme delta-aminolevulinic acid dehydratase (ALAd) in blood decreased exponentially in response to increased lead accumulation (R(2)=0.70, n=18) and represents therefore a specific effect marker for lead exposure. In the highest polluted area, an ALAd inhibition of 85% was reported. Since a higher metal exposure resulted in an increased metal accumulation and subsequent biomarker responses in a dose-dependent way, this study indicates the applicability of ALAd and MT levels in great tits for biomonitoring responses to heavy metal pollution.
authors.affiliation: Laboratory of Ecophysiology, Biochemistry and Toxicology, Department of Biology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium. caroline.vanparys@ua.ac.be
authors.forename: Caroline
authors.initials: C
authors.lastname: Vanparys
authors.forename: Tom
authors.initials: T
authors.lastname: Dauwe
authors.forename: Karen
authors.initials: K
authors.lastname: Van Campenhout
authors.forename: Lieven
authors.initials: L
authors.lastname: Bervoets
authors.forename: Wim
authors.initials: W
authors.lastname: De Coen
authors.forename: Ronny
authors.initials: R
authors.lastname: Blust
authors.forename: Marcel
authors.initials: M
authors.lastname: Eens
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis; D001717:Birds; D002104:Cadmium / Q000097:blood / Q000493:pharmacokinetics; D004305:Dose-Response Relationship, Drug; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000097:blood / Q000493:pharmacokinetics*; D005843:Geography; D007668:Kidney / Q000187:drug effects* / Q000378:metabolism; D007854:Lead / Q000097:blood / Q000493:pharmacokinetics; D008099:Liver / Q000187:drug effects* / Q000378:metabolism; D008668:Metallothionein / Q000097:blood / Q000494:pharmacology*; D019216:Metals, Heavy / Q000097:blood / Q000493:pharmacokinetics*; D000623:Porphobilinogen Synthase / Q000037:antagonists & inhibitors / Q000097:blood / Q000493:pharmacokinetics*; D014018:Tissue Distribution; D015032:Zinc / Q000097:blood / Q000493:pharmacokinetics
chemical_list: D015415:Biomarkers; D004785:Environmental Pollutants; D019216:Metals, Heavy; D002104:Cadmium; D007854:Lead; D008668:Metallothionein; D000623:Porphobilinogen Synthase; D015032:Zinc