The UI-R-CN1 library is a subtracted library derived from the following pool of seven normalized rat libraries: normalized rat seminal vesicles, normalized rat penis, normalized rat bladder, normalized rat cervix, normalized rat brown adipose, normalized rat fundus, and normalized rat salivary gland. It was constructed according to the procedure described by Bonaldo, Lennon & Soares (Genome Research Genome 6: 791-806, 1996). For construction of the CN1 library, plasmid DNA from the pool of normalized libraries was electroporated into competent bacteria for the production of single-stranded circular DNA. This was then used as a tracer in a subtractive hybridization with a driver (PCR amplified inserts from a plamid DNA template preparation) comprising: a) a pool of about 34,000 clones from the Rat Unigene Set corresponding to plates R-5-AA-NN excluding plates R-5-MM and MN. This pool represented 40% of the final driver population. b) a pool of about 29,000 clones from subtracted libraries CA0 and CA1 corresponding to plates R-CA0-AWV through R-CA0-AXS, R-CA0-AZX through R-CA0-BAZ, R-CA0-BFE through R-CA0-BHY, R-CA0-BJS, R-CA0-BKE, R-CA0-BKG-H, R-CA0-BKJ-K, R-CA0-BKP through R-CA0-BKS, R-CA0-BKU-V, R-CA0-BLY through R-CA0-BMA, R-CA0-BMC through R-CA0-BME, R-CA0-BNS, R-CA0-BOB through R-CA0-BOJ, R-CA0-BPA through R-CA0-BPG, R-CA1-BBA through R-CA1-BDA, R-CA1-BHZ through R-CA1-BJF, R-CA1-BJR, R-CA1-BJT through R-CA1-BKB, R-CA1-BKD, R-CA1-BKF, R-CA1-BKI, R-CA1-BKT, R-CA1-BLF, R-CA1-BLH through R-CA1-BLN, R-CA1-BLS, R-CA1-BLU-V, R-CA1-BNR, and R-CA1-BLE. The resulting pool represented 20% of the final driver population. c) a pool of about 15,000 clones from non-normalized libraries CS0s, CT0s, CU0s, CW0s, CX0s and normalized libaries CS0, CT0, CU0, CW0, and CX0 corresponding to plates R-CS0s-CBD through R-CS0s-CBO, R-CT0s-CAM through R-CT0s-CAX, R-CU0s-CBP through R-CU0s-CCA, R-CW0s-CCB through R-CW0s-CCM, R-CX0s-CCN through R-CX0s-CCX, R-CS0-BSD, R-CS0-BTD through R-CS0-BTV, R-CS0-BVM, R-CT0-BTW through R-CT0-BUP, R-CT0-BVN, R-CU0-BUQ through R-CU0-BVL, R-CW0-BVV through R-CW0-BWP, R-CW0-BXN through R-CW0-BXO, R-CX0-BWQ through R-CX0-BXM. The resulting pool represented 5% of the final driver population. d) a pool of about 5,000 clones (1,000 from non-normalized eye library CV0 and 4,000 from normalized eye library CV1) corresponding to plates R-CV0-BRH through R-CV0-BRR, R-CV1-BRS through R-CV1-BSC, R-CV1-BSE through R-CV1-BTC, and R-CV1-BVO through R-CV1-BVU. This pool represented about 5% of the final driver population. e) A pool of about 10,000 clones from subtracted library BS2, BV0 and BV0p (7-9.5 kb cDNA library fraction from rat whole embryo), and BX0 (0.5-7kb cDNA library fraction from rat whole embryo) corresponding to plates R-BS2-BDB through R-BS2-BFB, R-BV0-ANK through R-BV0-ANR, R-BV0p-AOI through R-BV0p-AOX, and R-BX0-AQY through R-BX0-ASH. The resulting pool represented 5% of the final driver population. f) a pool of about 7,000 clones from the seven non-normalized libraries that make up the tracer including CY0, CZ0, DA0, DB0, DC0, DD0, and DE0 corresponding to plates R-CY0-BXP through R-CY0-BXZ, R-CZ0-BYA through R-CZ0-BYI, R-CZ0-BZB-C, R-DA0-BYJ through R-DA0-BYP, R-DA0-BZD through R-DA0-BZH, R-DB0-BYQ through R-DB0-BZA, R-DC0-BZI through R-DC0-BZQ, R-DC0-CAY through R-DC0-CBA, R-DD0-BZR through R-DD0-CAA, R-DD0-CBB-C, and R-DE0-CAB through R-DE0-CAL. The resulting pool represented about 10% of the final driver population. g) a pool of about 2,000 clones from the pool of normalized libraries, CN0, that makes up the tracer. The corresponding plates are R-CN0-BKW through R-CN0-BLD, R-CN0-BLG, R-CN0-BLP through R-CNO-BLR, R-CN0-BLT, R-CN0-BLW-X, R-CN0-BMB, and R-CN0-BMF through R-CN0-BML. This pool represented 5% of the final driver population. h) a pool of the 28 most abundant clones in the CN0 pool corresponding to the following addresses: bkw-a-09-0-UI, bkw-b-09-0-UI, bkw-b-11-0-UI, bkx-b-10-0-UI, bkx-d-01-0-UI, bkx-d-06-0-UI, bkx-g-08-0-UI, bkx-h-12-0-UI, bky-a-05-0-UI, bkz-a-06-0-UI, bkz-a-11-0-UI, bkz-c-06-0-UI, bkz-c-09-0-UI, bkz-d-10-0-UI, bla-a-01-0-UI, bla-a-02-0-UI, bla-f-04-0-UI, bla-g-07-0-UI, bla-g-12-0-UI, blb-a-12-0-UI, blb-f-02-0-UI, blc-a-11-0-UI, blc-e-95-0-UI, bld-1-08-0-UI, bld-f-02-0-UI, blq-h-04-0-UI, blr-a-05-0-UI, blt-f-08-0-UI. This pool represented 5% of the final driver population. i) One abundant CN0 clone (corresponding to the address bkz-a-11-0-UI) was digested with Not I and Eco RI and the resulting insert was gel purified. This purified insert was added directly to the driver so that it represented 5% of the final driver population.