title: Gene expression patterns and life cycle responses of toxicant-exposed chironomids.
abstract: Cellular stress responses are frequently presumed to be more sensitive than traditional ecotoxicological life cycle end points such as survival and growth. Yet, the focus to reduce test duration and to generate more sensitive end points has caused transcriptomics studies to be performed at low doses during short exposures, separately and independently from traditional ecotoxicity tests, making comparisons with life cycle end points indirect. Therefore we aimed to directly compare the effects on growth, survival, and gene expression of the nonbiting midge Chironomus riparius. To this purpose, we simultaneously analyzed life cycle and transcriptomics responses of chironomid larvae exposed to four model toxicants. We observed that already at the lowest test concentrations many transcripts were significantly differentially expressed, while the life cycle end points of C. riparius were hardly affected. Analysis of the differentially expressed transcripts showed that at the lowest test concentrations substantial and biologically relevant cellular stress was induced and that many transcripts responded already maximally at these lowest test concentrations. The direct comparison between molecular end life cycle responses after fourteen days of exposure revealed that gene expression is more sensitive to toxicant exposure than life cycle end points, underlining the potential of transcriptomics for ecotoxicity testing and environmental risk assessment.
authors.affiliation: Microarray Department and Integrative Bioinformatics Unit, Swammerdam Institute for Life Sciences (SILS), University of Amsterdam, Sciencepark 904, 1098 XH Amsterdam, The Netherlands. M.Marinkovic@uva.nl
authors.forename: Marino
authors.initials: M
authors.lastname: Marinković
authors.forename: Wim C
authors.initials: WC
authors.lastname: de Leeuw
authors.forename: Wim A
authors.initials: WA
authors.lastname: Ensink
authors.forename: Mark
authors.initials: M
authors.lastname: de Jong
authors.forename: Timo M
authors.initials: TM
authors.lastname: Breit
authors.forename: Wim
authors.initials: W
authors.lastname: Admiraal
authors.forename: Michiel H S
authors.initials: MH
authors.lastname: Kraak
authors.forename: Martijs J
authors.initials: MJ
authors.lastname: Jonker
mesh_terms: D000818:Animals; D002683:Chironomidae / Q000187:drug effects* / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004781:Environmental Exposure; D005786:Gene Expression Regulation; D007814:Larva / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D008670:Metals / Q000633:toxicity; D020411:Oligonucleotide Array Sequence Analysis; D010616:Phenanthrenes / Q000633:toxicity; D017422:Sequence Analysis, DNA; D014220:Trialkyltin Compounds / Q000633:toxicity; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D008670:Metals; D010616:Phenanthrenes; D014220:Trialkyltin Compounds; D014874:Water Pollutants, Chemical; C031181:phenanthrene; C011559:tributyltin