Eisenia fetida

> Sequencing project

Auteur: C. Cocquerelle

TThis worm (Eisenia fetida) lives on fertilizer and is known as “striped worm”. It lives by decomposing organic material and is about 50 miliimeters long.

Human activities, especially metallurgical ones, lead to accumulation of Metal Trace Elements (MTEs) in the topsoils, where one typically observes concentrations largely exceeding the natural background. Heavy contaminations of soils are a threat to public health. Cases of cancer related to high cadmium concentrations have been described. Soil health and sustainable productivity depend on living organisms, which affect the cycling rate and availability of the major organic and non-organic compounds in their constant search for food and energy sources. High concentrations of MTEs constitute a major stress likely to affect the organisms exposed to the polluted soils and the functioning of the ecosystems. Numerous studies on plants and animals living in close contact with soils have been carried out in order to better understand the mechanisms of action of contaminants, the physiological changes, the mechanisms of detoxification and of acclimation induced by metallic stress (see Morgan et al., 2007). One of the most studied zoological groups is the Annelida Oligochaeta group. These animals play a key role in most continental ecosystems, represent an important part of the soil macrofauna and are integral to the maintenance of the structure and the fertility of soils.

Eisenia fetida is an ecotoxicologically important species. This Annelida Oligocheta was chosen to perform this present work because this model is recommended in ecotoxicology by OECD (1984; 2004), is easily bred and has been the subject of many physiological studies. Although studied a lot, the number of nucleotidic sequences available in genomic libraries was relatively low until recently.

The emergence of molecular biology techniques applied to ecotoxicology, allows a better understanding of the modes of action of contaminants in living organisms. Indeed, gene expression profiles elucidate the effect of environmental stressors on the genome and its products. Thus, analysis of changes of gene expression is a powerful tool to (1) diagnose the existence of a stress and to (2) analyse mechanistically the response to a stressor (see Robbens et al., 2007 ; Brulle et al., 2010).

> Sequencing project