Digital image processing for rapid analysis of differentially expressed transcripts on high-density cDNA arrays

Usage of filter arrays is becoming increasingly attractive for many researc h laboratories involved indetermination of gene-expression profiles. Howeve r analysis of numerous spots, representing genes or partial gene sequences (ESTs), is still tedious work involving the ordered analysis of vast amount s of numerical tabular data. We present a vapid and efficient method for th e visual identification of differentially expressed targets on high-density cDNA filter arrays using standard laboratory equipment and standard softwa re, which is available for free. The method we introduce provides an inexpe nsive alternative, and no changes in the experimental set up are required. Our results were verified by densitometric analyses performed with an estab lished system.