Eisenia fetida

In previous studies, we partially cloned and measured the gene expression of 16 potential biomarkers in the ecotoxicologically important species Eisenia fetida after in vivo exposure to Cd in artificial OECD soil. Effectors were chosen among highly preserved ones for which variations (in terms of protein quantity and or expression) following metal exposure were reported in the literature. Expression was measured in cœlomocytes (immune cells) since the majority of the selected effectors are known to be involved in defence mechanisms (see Brulle et al., 2006; Brulle et al., 2007; Brulle et al., 2008a). Thus, analysis of changes in gene expression is a powerful tool, firstly to diagnose the existence of a stress in a population and secondly to analyze mechanistically the response to a stress. In this context, sequence information is a prerequisite.

Auteur: C. Cocquerelle

Eisenia fetida

Recently, a Suppression Substractive Hybridization (SSH) approach was used to construct four cDNA libraries enriched in up- or down-regulated transcripts from the immune circulating cells of Eisenia fetida exposed to metallic pollution for 1 or 14 days (Brulle et al., 2008b). In a medium scale sequencing effort, 1536 SSH derived cDNA sequences have been analysed and annotated. This work allowed the enrichment of the genomic databases and the identification of new MTEs exposure biomarkers. Based on this work, a sequencing project has been submitted by Pr. F. Vandenbulcke and realized by the Genoscope (Project N°73). The aim of this project was to perform extended sequencing of our 4 SSH libraries (notably the reverse SSH library at 1 day exposition not performed to date). 20,000 clones (5000 for each of the 4 libraries) have been sequenced using the Sanger technology. 20,000 Expressed Sequence Tags (5,000 for each of the 4 libraries) have been sequenced, and analysed using the PartiGene analysis suite, and decorated with functional annotations (GO, EC and KEGG identifiers) with annot8r. Bioinformatic analysis was performed in collaboration with Professeur Mark Blaxter (Institute of Evolutionary Biology, University of Edinburgh). Approximately 5000 unique sequences have been obtained (link).

These 4000 unique gene objects constitute a first set of sequences which will be spotted on a Eisenia fetida cDNA microarray in order to study expression profiling when this “test-organism” is facing environmental stress such as a pollution.

References

Brulle F., Mitta G., Cocquerelle C., Vieau D., Lemière S., Lepretre A., Vandenbulcke F. (2006). Cloning and real-time PCR testing of 14 potential biomarkers in Eisenia fetida following cadmium exposure. Environmental Science and Technology, 40(8), 2844-2850.

Brulle F., Mitta G., Leroux R., Lemière S., Lepretre A., Vandenbulcke F. (2007). The strong induction of metallothionein gene following cadmium exposure transiently affects the expression of many genes in Eisenia fetida: a trade-off mechanism?. Comparative Biochemistry and Physiology Part C (Pharmacology and Toxicology), 144(4), 334-341.

Brulle F., Cocquerelle C., Nda Wamalah A., Morgan AJ., Kille P, Leprêtre A. and Vandenbulcke F. (2008a) cDNA cloning and expression analysis of Eisenia fetida (Annelida; Oligochaeta) phytochelatin synthase under cadmium exposure. Ecotoxicology and Environmental Safety (Highlighted article).Vol 71 (1), p47-55.

Brulle F., Cocquerelle C., Mitta G., Castric V., Douay F., Leprêtre A., and Vandenbulcke F. (2008b) Identification and expression profile of gene transcripts differentially expressed during metallic exposure in Eisenia fetida. Vol 32 (12), p1441-1453. Developmental and Comparative Immunology.

Brulle F., Vandenbulcke F., 2009, Développement de biomarqueurs d’exposition aux métaux basés/fondés sur les fonctions physiologiques de l’annélide oligochète Eisenia fetida. Etude et Gestion des Sols. Volume 16(3/4), 159-175.

Brulle Franck, Morgan A. John, Cocquerelle Claude & Vandenbulcke Franck. (2010). Transcriptomic underpinning of toxicant-mediated physiological function alterations in three terrestrial invertebrate taxa: a review. Submitted.

Bernard F., Brulle F., Douay F., Lemière S., Demuynck S. and Vandenbulcke F. (2010). Metallic trace element body burdens and gene expression analysis of biomarker candidates in Eisenia fetida, using an “exposure/depuration” experimental scheme with field soils. In press. Ecotoxicology and Environmental Safety, 2010, doi : 10.1016/j.ecoenv.2010.01.010.

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