Investigating trascriptional responses in Mytilus galloprovincialis: Why is the cDNA microarray approach appealing?

The biomarkers currently applied in mussels can trace at sub-cellular, cytological or physiological level the exposure and early effects of toxic contaminants, thus facilitating the identification of ecological risk and the management of coastal ecosystems. However, only a few of these measures have been validated and each of them illustrates only partially the overall organism response to natural and anthropogenic stress factors. The rapid technological progresses and the highly informative results obtained in other species induced us to start gene identification and expression profiling in Mytilus galloprovincialis. The massive production of 3’ESTs yielded a collection of sequences specifically tagging genes expressed in the most typical mussel tissues (gills, digestive glands, foot, muscles and ligaments, mantle and gonads). Details of the cloning procedure made the resulting cDNA inserts suitable for the microarray definition. In fact, following accurate selection and re-purification, the 1731 transcript tags plus a number of control sequences are now printed on slide (MytArray 1.0). The microarray performance has been assessed on normal mussels, mussels treated in laboratory with heavy metals or organic compounds and mussels collected from putatively clean or contaminated coastal sites (Venice lagoon area, Italy). The resulting data confirm the great potential of the microarray technology for investigating basic gene expression and stress-induced responses in mussels. The use of MytArray 1.0 in parallel to measures based on a smaller number of known genes or proteins will likely allow a better understanding of the biochemical pathways mediating cell responses to toxic factors. (‘‘Supported by Co.Ri.La. and MIUR’’.)