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Metabolomics of microliter hemolymph samples enables an improved understanding of the combined metabolic and transcriptional responses of Daphnia magna to cadmium
Citation:
POYNTON, H., N. S. Taylor, J. Hicks, K. Colson, S. Chan, C. Clark, L. Scanlan, A. V. Loguinov, C. Vulpe, AND M. R. Viant. Metabolomics of microliter hemolymph samples enables an improved understanding of the combined metabolic and transcriptional responses of Daphnia magna to cadmium. ENVIRONMENTAL SCIENCE AND TECHNOLOGY. John Wiley & Sons, Ltd., Indianapolis, IN, 45:3710-3717, (2011).
Impact/Purpose:
We demonstrated the feasibility of metabolomics on Daphnia magna hemolymph and compared metabolomic and transcriptomic profiles to produce a model of cadmium toxicity.
Description:
Cadmium is a toxic metal causing sublethal and chronic effects in crustaceans. Omic technologies offer unprecedented opportunities to better understand modes of toxicity by providing a holistic view of the molecular changes underlying physiological disruption. We sought to use gene expression and metabolomic analyses to reveal the processes leading to chronic Cd toxicity in the indicator species, Daphnia magna, after a 24-h sublethal exposure. We first confirmed that metabolites can be detected and identified in small volumes of D. magna hemolymph using Fourier transform ion cyclotron resonance mass spectrometry and NMR spectroscopy. We then compared the altered metabolite levels from a mass spectrometry metabolomics study to differentially expressed genes identified by a D. magna 44k oligonucleotide microarray. Metabolomics identified several essential amino acids, nucleotides and fatty acids as decreased in D. magna hemolymph following Cd exposure. Transcriptional changes included decreased levels of digestive enzymes and increased expression of genes related to embryonic development. The integration of metabolomic and transcriptomic profiles, as well as incorporation of results from previous studies, has enabled construction of a conceptual model detailing how sublethal Cd disrupts energy reserves and reproduction resulting in chronic toxicity.