T2 PM 'Omic' Technologies: Current and Future Applications to Environmental Toxicology (Part 2)
Tuesday, 15 November 2005: 1:50 PM - 5:30 PM in Ballroom 2

(SPU-1117-823411) Using transcriptomic responses of model and environmental sentinel worms to investigate the mechanistic basis of toxicity.

Svendsen, C¹, Spurgeon, D¹, Chaseley, J², Morgan, A², Sturzenbaum, S², Kille, P², Hedley, B³, Blaxter, M³, Hankard, P¹, Lister, L¹, ¹ Centre for Ecology and Hydrology, Monks Wood, Cambs, England² University of Cardiff, Cardiff, Wales³ University of Edinburgh, Edinburgh, Scotland

ABSTRACT- Over the past three years the ECOWORM project has been developing an approach to understand the mechanistic basis of the toxicological effects of three chemicals (one metal, one narcotic organic and one pesticide) on the life-cycle of two worm species, the model nematode Caenorhabditis elegans and the environmental sentinel Lumbricus rubellus. Through developing new toxicological test methods; to recorded effect of each compound on key life-cycle traits; through ecological modelling to understand the influences of these of fitness; to the use of off-the-shelf oligonucleotide (for the nematode) and custom cDNA microarrays (for the earthworm), we have sought to link mechanistic effects to phenotypic change. In the earthworm we have sequenced over 15000 EST clones from 7 full length cDNA libraries representing different life stages of the earthworm (cocoons, juveniles and adults) and exposures (cadmium, fluoranthene and atrazine). These have been automatically submitted to the public EST database (dbEST) and are fully searchable and annotated on our website www.earthworms.org. Ontological analysis of the sequenced cDNA from each library provided initial data concerning the probable modes of action of each of the toxicant for earthworm. These being different for each of the three contaminants considered. A set of these cDNA has been used to construct a custom microarray for the earthworm, which when used in conjunction with a full genome microarray for the nematode has been used to analyse transcriptomic changes in tissue samples collected at the same time as the life-cycle data. By using modelling approaches such as the Dynamic Energy Budget model, we have sought to assess possible ecological mechanisms of the toxic effects of each contaminant (effects of assimilation, maintenance, growth, reproduction and hazard to the embryo) and attempted to validate these by relating transcriptional changes to the predicted mode of toxic effects. Our studies have also allowed us to identify a number of molecular responses that are characteristic of the particular pollutant to which each of the two worm species have been exposed. Our studies are, thus, enabling us to establish the mechanistic basis of ecologically significance adverse effects on the life-cycle of the two species.

Key words: TRANSCRIPTOMICS, MICROARRAY, NEMATODE, EARTHWORM