Development of gene expression profile on different sampling sites of the Ebro River

The zebra mussel is present in Spain since early 2000,s, when it was discovered in the lower part of the Ebro river. To study the gene expression pattern of different populations of zebra mussel a long the Ebro River we use a custom microarray developed in our laboratory, using 4057 publicly available DNA sequences from Dreissena polymorpha and other related genera. Also it was used an external sampling site located in Sitjar Dam, about 200km form the Ebro river. Transcriptome profiles were analysed using the gills of individuals collected in the same period (20-23 March) to diminish seasonal effects. A total of 755 transcripts changed significantly their mRNA levels among the sites of the study (ANOVA p<0.01, fc ±1.5). Genes encoding for xenobiotic, energetic and calcium metabolism and cell proliferation were those showing the highest differences among populations. Geographical origin appeared as the major driver of the differences among the studied populations, as the transcriptomic profiles from four populations collected within a radius of few km around the Flix factory clustered together and separated from those from other distant populations both upstream the Ebro River or in the Sitjar dam. Differences on gene expression pattern were measure in gills of Dreissena polymorpha in different populations in five populations along the Ebro river and one population in Sitjar dam. The collection of samples were done during Srping (March). For the microarray it was used 2 replicates of each sites of the study.