title: A multi-platform metabolomics approach demonstrates changes in energy metabolism and the transsulfuration pathway in Chironomus tepperi following exposure to zinc.
abstract: Measuring biological responses in resident biota is a commonly used approach to monitoring polluted habitats. The challenge is to choose sensitive and, ideally, stressor-specific endpoints that reflect the responses of the ecosystem. Metabolomics is a potentially useful approach for identifying sensitive and consistent responses since it provides a holistic view to understanding the effects of exposure to chemicals upon the physiological functioning of organisms. In this study, we exposed the aquatic non-biting midge, Chironomus tepperi, to two concentrations of zinc chloride and measured global changes in polar metabolite levels using an untargeted gas chromatography-mass spectrometry (GC-MS) analysis and a targeted liquid chromatography-mass spectrometry (LC-MS) analysis of amine-containing metabolites. These data were correlated with changes in the expression of a number of target genes. Zinc exposure resulted in a reduction in levels of intermediates in carbohydrate metabolism (i.e., glucose 6-phosphate, fructose 6-phosphate and disaccharides) and an increase in a number of TCA cycle intermediates. Zinc exposure also resulted in decreases in concentrations of the amine containing metabolites, lanthionine, methionine and cystathionine, and an increase in metallothionein gene expression. Methionine and cystathionine are intermediates in the transsulfuration pathway which is involved in the conversion of methionine to cysteine. These responses provide an understanding of the pathways affected by zinc toxicity, and how these effects are different to other heavy metals such as cadmium and copper. The use of complementary metabolomics analytical approaches was particularly useful for understanding the effects of zinc exposure and importantly, identified a suite of candidate biomarkers of zinc exposure useful for the development of biomonitoring programs.
authors.affiliation: Centre for Aquatic Pollution, Identification and Management (CAPIM), School of BioSciences, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, 30 Flemington Road, Parkville, 3052, Australia. Electronic address: hoskins@unimelb.edu.au.
authors.forename: Sara M
authors.initials: SM
authors.lastname: Long
authors.affiliation: Metabolomics Australia, Bio21 Molecular Science and Biotechnology Institute, 30 Flemington Road, Parkville, 3052, Australia. Electronic address: dedreia@unimelb.edu.au.
authors.forename: Dedreia L
authors.initials: DL
authors.lastname: Tull
authors.affiliation: Centre for Aquatic Pollution, Identification and Management (CAPIM), School of BioSciences, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, 30 Flemington Road, Parkville, 3052, Australia; Centre for Aquatic Pollution, Identification and Management (CAPIM), School of BioSciences, The University of Melbourne, 3010, Australia. Electronic address: k.jeppe@unimelb.edu.au.
authors.forename: Katherine J
authors.initials: KJ
authors.lastname: Jeppe
authors.affiliation: Metabolomics Australia, Bio21 Molecular Science and Biotechnology Institute, 30 Flemington Road, Parkville, 3052, Australia. Electronic address: desouzad@unimelb.edu.au.
authors.forename: David P
authors.initials: DP
authors.lastname: De Souza
authors.affiliation: Metabolomics Australia, Bio21 Molecular Science and Biotechnology Institute, 30 Flemington Road, Parkville, 3052, Australia. Electronic address: sdayalan@unimelb.edu.au.
authors.forename: Saravanan
authors.initials: S
authors.lastname: Dayalan
authors.affiliation: Centre for Aquatic Pollution, Identification and Management (CAPIM), School of BioSciences, The University of Melbourne, 3010, Australia. Electronic address: vpet@unimelb.edu.au.
authors.forename: Vincent J
authors.initials: VJ
authors.lastname: Pettigrove
authors.affiliation: Metabolomics Australia, Bio21 Molecular Science and Biotechnology Institute, 30 Flemington Road, Parkville, 3052, Australia. Electronic address: malcolmm@unimelb.edu.au.
authors.forename: Malcolm J
authors.initials: MJ
authors.lastname: McConville
authors.affiliation: Centre for Aquatic Pollution, Identification and Management (CAPIM), School of BioSciences, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, 30 Flemington Road, Parkville, 3052, Australia; School of BioSciences, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, 30 Flemington Road, Parkville, 3052, Australia. Electronic address: ary@unimelb.edu.au.
authors.forename: Ary A
authors.initials: AA
authors.lastname: Hoffmann
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002683:Chironomidae / Q000187:drug effects* / Q000378:metabolism; D002712:Chlorides / Q000633:toxicity*; D002853:Chromatography, Liquid; D004734:Energy Metabolism / Q000187:drug effects*; D004784:Environmental Monitoring; D008401:Gas Chromatography-Mass Spectrometry; D015870:Gene Expression / Q000187:drug effects*; D055432:Metabolomics; D011897:Random Allocation; D015398:Signal Transduction / Q000187:drug effects; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D017967:Zinc Compounds / Q000633:toxicity*
chemical_list: D015415:Biomarkers; D002712:Chlorides; D014874:Water Pollutants, Chemical; D017967:Zinc Compounds; C016837:zinc chloride
keywords: Biomarkers; Chironomus; Energy metabolism; Gene expression; Transsulfuration; Zinc