Application of differential display RT-PCR to identify porcine liver ESTs

Differential display banding patterns of liver and nine other tissues were produced in order to isolate porcine expressed sequence tags (ESTs), representing genes active in liver while avoiding redundant analysis of housekeeping genes. We cloned and sequenced those cDNA fragments that were unique to the liver banding pattern or that appeared in liver and a maximum of four other tissues. We analyzed 240 sequences that represent 200 distinct ESTs/genes and that make up the first list of liver ESTs in the pig. Ninety-one clones correspond to known genes and 109 clones showed no significant match with any gene or DNA sequence in GenBank and EMBL databases. Fifty-eight clones represent 18 distinct genes, the most abundant representing the albumin gene (13/240). The majority of genes that were represented by more than one clone code for proteins released by the liver into the plasma. We demonstrated the suitability of the differential display reverse transcription polymerase chain reaction approach for the detection of porcine liver ESTs. It is shown that this approach is appropriate to reduce redundant analysis of clones containing the same sequence.