Washington, June 3 : A new research has revealed the molecular mechanisms by which earthworms adapt to exposure to soil contaminants, which can provide clues for dealing with soil pollution.
The research takes into account the case of the earthworm Lumbricus rubellus, which has long been known as an 'ecosystem engineer' for the role it plays in water, nutrient and carbon cycling in a range of tropical and temperate soils, and is widely used as a model organism for soil testing.
However, standard lab assays do not reveal the molecular mechanisms by which L. rubellus adapts to exposure to soil contaminants.
Although the L. rubellus genome has not yet been sequenced, a comprehensive expressed sequence tag dataset is now available that enables the development of tools that bring the earthworm into the genomics arena.
Two teams, funded by the UK Natural Environment Research Council and led by Peter Kille of Cardiff University, have jointly carried out a research on the use of a systems toxicology approach to understanding the impact of four soil contaminants on L. rubellus.
Using a new 8,000-element microarray, they describe the transcriptome profile of L. rubellus exposed to copper, cadmium, the polyaromatic hydrocarbon fluoroanthene, and the agrochemical atrazine.
In both studies, this approach revealed subtle changes induced by the toxic chemicals in earthworm gene expression patterns.
The second study, which specifically focused on copper exposure, extended the approach by identifying the consequences of the genetic changes in terms of altered metabolism (impact to their metabolomic profile) in conjunction with large-scale physical changes in worm health.
The molecular approach to monitor ecosystem effects of toxins allows scientists to understand not only the uniqueness of earthworms, but is also an important step towards the better understanding of how the earthworm has evolved adaptive mechanisms to deal with soil pollution.
This multidisciplinary research shows that a systems approach to ecotoxicology, combining technologies usually used in isolation, can be a powerful tool for understanding the response of an ecologically important organism to contaminants, and opens up the possibility of new and more effective soil monitoring and bioremediation strategies.