We generated the PEDE (Pig EST Data Explorer; http://pede.dna.affrc.go.jp/) database using sequences assembled from porcine 5' ESTs from oligo-capped full-length cDNA libraries. Thus far we have performed EST analysis of various organs (thymus, spleen, uterus, lung, liver, ovary and peripheral blood mononuclear cells) and assembled 68,076 high-quality sequences into 5546 contigs and 28,461 singlets. PEDE provides a search interface for getting results of homology searches and enables users to obtain information on sequence data and cDNA clones of interest. Single-nucleotide polymorphisms detected through comparison of the EST sequences are classified by origin (western and oriental breeds) and are searchable in the database. This database system can accelerate analyses of livestock traits and yields information that can lead to new applications in pigs as model systems for medical research.

The development of informative polymorphic markers is essential for QTL mapping. We developed 50 microsatellite markers from BAC clones containing genes that were predicted to map swine chromosome 4 (SSC4) according to comparative analysis between human and swine chromosomes, and constructed a linkage map that consisted of 37 markers including 24 markers closely linked to genes in BAC clones. Microsatellite markers were developed by direct-sequencing of BAC clones and our results demonstrated that this method was effective for developing microsatellite markers in specific regions on chromosomes. Effective development of microsatellite markers closely linked to genes can further accelerate the comparative studies of chromosomes between different species.

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The wild-type p53 protein suppresses transformation, but certain missense mutants of p53 can transform cells. Although the wild-type p53 protein contains a trnscriptional activation domain, no p53-responsive element has been identified. Here, we identified the p53-responsive element within the Tax-responsive element [21-base-pair (bp) enhancer] of human T-cef leukemia virus type I. Mutation analysis of the 21-bp enhancer indicated that the 16-bp sequence containing the cAMP-responsive element and its surrounding sequence was responsible for p53-induced transactivation. This 16-bp sequence was demonstrated to bind specifically to wild-type human p53 protein in vitro. Using a series of deletion mutants of p53, we showed that almost the entire region of p53 is needed for the transactivating capacity. Furthermore, the transforming mutants of p53 were unable to act as transcriptional activators. The p53-responsive element identified here should be useful to analyze the mechanism by which p53 regulates expression of a set of genes with a negative effect on cellular growth.