(A) Agarose/EtBr gel-electrophoresis of non-normalized (1) andnormalized (2) human cDNA samples; (B) concentration of abundant transcripts in these samples revealed byVirtual Northern blot. GPDH – glyceraldehyde-3-phosphate dehydrogenase;UBC – ubiquitin C; M, 1-kb DNA size markers (SibEnzyme). (C) Normalization significantly increases gene discovery rate of cDNAlibrary. Transcript distribution in standard and normalized cDNAlibraries from Aplysia neurons: yellow – all sequences, blue – uniquesequences; green – non-unique sequences