title: Molecular responses during cadmium-induced stress in Daphnia magna: integration of differential gene expression with higher-level effects.
abstract: DNA microarrays offer great potential in revealing insight into mechanistic toxicity of contaminants. The aim of the present study was (i) to gain insight in concentration- and time-dependent cadmium-induced molecular responses by using a customized Daphnia magna microarray, and (ii) to compare the gene expression profiles with effects at higher levels of biological organization (e.g. total energy budget and growth). Daphnids were exposed to three cadmium concentrations (nominal value of 10, 50, 100microg/l) for two time intervals (48 and 96h). In general, dynamic expression patterns were obtained with a clear increase of gene expression changes at higher concentrations and longer exposure duration. Microarray analysis revealed cadmium affected molecular pathways associated with processes such as digestion, oxygen transport, cuticula metabolism and embryo development. These effects were compared with higher-level effects (energy budgets and growth). For instance, next to reduced energy budgets due to a decline in lipid, carbohydrate and protein content, we found an up-regulated expression of genes related to digestive processes (e.g. alpha-esterase, cellulase, alpha-amylase). Furthermore, cadmium affected the expression of genes coding for proteins involved in molecular pathways associated with immune response, stress response, cell adhesion, visual perception and signal transduction in the present study.
authors.affiliation: Department of Biology, Laboratory for Ecophysiology, Biochemistry and Toxicology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium. anneleen.soetaert@ua.ac.be
authors.forename: Anneleen
authors.initials: A
authors.lastname: Soetaert
authors.forename: Tine
authors.initials: T
authors.lastname: Vandenbrouck
authors.forename: Karlijn
authors.initials: K
authors.lastname: van der Ven
authors.forename: Marleen
authors.initials: M
authors.lastname: Maras
authors.forename: Piet
authors.initials: P
authors.lastname: van Remortel
authors.forename: Ronny
authors.initials: R
authors.lastname: Blust
authors.forename: Wim M
authors.initials: WM
authors.lastname: De Coen
mesh_terms: D000818:Animals; D002104:Cadmium / Q000633:toxicity*; D002105:Cadmium Poisoning / Q000235:genetics / Q000378:metabolism; D003621:Daphnia / Q000187:drug effects* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004734:Energy Metabolism; D020869:Gene Expression Profiling; D020411:Oligonucleotide Array Sequence Analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D002104:Cadmium