The UI-R-BJ0 library is a subtracted library derived from the UI-R-AA1, UI-R-AB1, UI-R-AC1, UI-R-AD1, UI-R-AE1, UI-R-AF1, and UI-R-AG1 libraries. These libraries represent tissues from rat atrium at 16.5 dpc, ventricle at 16.5 dpc, AV canal at 16.5 dpc, atrium at 15 dpc, ventricle at 15 dpc, AV canal at 15 dpc, and ventricle at 13 dpc. The tag is a string of 5-6 nucleotides present between the Not I site and the oligo-dT track. The library was constructed as described by Bonaldo, Lennon and Soares, Genome Research 6: 791-806, 1996.