Comparative Transcriptomic Responses to Chronic Cadmium, Fluoranthene, and Atrazine Exposure in Lumbricus rubellus

Abstract

Transcriptional responses of a soil-dwelling organism (the earthworm Lumbricus rubellus) to three chemicals, cadmium (Cd), fluoranthene (FA), and atrazine (AZ), were measured following chronic exposure, with the aim of identifying the nature of any shared transcriptional response. Principal component analysis indicated full or partial separation of control and exposed samples for each compound but not for the composite set of all control and exposed samples. Partial least-squares discriminant analysis allowed separation of the control and exposed samples for each chemical and also for the composite data set, suggesting a common transcriptional response to exposure. Genes identified as changing in expression level (by the least stringent test for significance) following exposure to two chemicals indicated a substantial number of common genes (> 127). The three compound overlapping gene set, however, comprised only 25 genes. We suggest that the low commonality in transcriptional response may be linked to the chronic concentrations (approximately 10% EC50) and chronic duration (28 days) used. Annotations of the three compound overlapping gene set indicated that genes from pathways most often associated with responses to environmental stress, such as heat shock, phase I and II metabolism, antioxidant defense, and cation balance, were not represented. The strongest annotation signature was for genes important in mitochondrial function and energy metabolism.

Environmental metabolomics: a critical review and future perspectives

“…E. fetida and L. rubellus are the only two species to date to have cDNA microarrays available for more comprehensive ecotoxicogenomic studies (Gong et al 2007;Owen et al 2008;Svendsen et al 2008), and have obvious advantages for laboratory and field studies respectively, given their status as an important ecotoxicological model (E. fetida), and the extent of already existing metabolomic data and greater relevance to soil contamination (L. rubellus). Studies have been carried out at various levels of environmental relevance (paper contact test, spiked soil exposures, and actual contaminated sites), and for both toxic metals (copper, cadmium, and metal contaminated sites) and organics (pesticides, and model aromatic compounds).…”

Identification and Optimization of Classifier Genes from Multi-Class Earthworm Microarray Dataset

“…Similarly, Nota and co-workers recently identified a set of 188 genes from expression profiles of the springtail ( Folsomia candida ) exposed to a soil spiked with six different metals using the uncorrelated shrunken centroid method, and predicted an independent test soils set with an accuracy of 83% but failed on field soils collected from two cobalt-contaminated sites using this gene set [11]. Several other studies also reported a varying degree of success in the identification of classifier genes in both aquatic species like the zebrafish ( Danio rerio ) [12], the common carp Cyprinus carpio [14] and the water flea Daphnia magna [15], and terrestrial organisms such as the earthworm Lumbricus rubellus [16].…”

Application of physiologically based modelling and transcriptomics to probe the systems toxicology of aldicarb for Caenorhabditis elegans (Maupas 1900)

“…The measurement of toxicant induced impacts on gene and protein expression and metabolite concentrations offer the chance to understand how effects on life history are mediated at the molecular level. The use of toxicogenomics in ecotoxicology is rapidly evolving and increasing (Williams et al 2003; Heckmann et al 2006; Soetaert et al 2007; Svendsen et al 2008; Owen et al 2008; Bundy et al 2008). To date, however, only a few of these studies have attempted to link gene/protein expression responses to life history changes elicited by toxicant exposure (Connon et al 2008; Swain et al 2010).…”