With the aim to study the mode of action of environmentally relevant chemicals in eels, the multi tissue transcriptome was sequenced (454 Titanium Roche) in order to design a high density custom oligo-microarray (eArray, Agilent-technologies). Previous to the sequencing attempt, eels were acclimatised to 2 different conditions, seawater and fresh water. From each eel liiver, brain, gills, spleen, stomach and muscle were dissected and RNA extracted. To this RNA pool the RNA of 2 whole glass eels was added. The RNA mix was done mixing equal amount of RNA from each tissue.