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.

Arterial wall enhancement is related to aging and is probably due to neovascularity in association with atherosclerotic plaques. This finding may permit assessment of intracranial atherosclerosis and other vascular diseases.

A porcine bacterial artificial chromosome (BAC) library consisting of 103,488 clones has been constructed. The average insert size in the BAC vector was calculated to be 133 kb based on the examination of 189 randomly selected clones, indicating that the library contained 4.4 genome equivalents. The library can be screened by two-step PCR. The first screening step is performed on 22 superpools, each containing 4704 clones (49 x 96 well plates). In the second screening step, 49 plates comprising a superpool are arrayed in a 7 x 7 matrix and 4D-PCR is performed. Screening of the library superpools by PCR for 125 marker sequences selected from different regions of swine genome revealed 123 sequences, indicating that the library is not biased. Subsequent screenings (4D-PCR) were successfully applied for identification of clones containing each marker sequence. This porcine BAC library and the PCR screening system are useful for isolation of genomic DNA fragments containing desired sequences.

We formerly released the porcine expressed sequence tag (EST) database Pig EST Data Explorer (PEDE; ), which comprised 68 076 high-quality ESTs obtained by using full-length-enriched cDNA libraries derived from seven tissues. We have added eight tissues and cell types to the EST analysis and have integrated 94 555 additional high-quality ESTs into the database. We also fully sequenced the inserts of 10 147 of the cDNA clones that had undergone EST analysis; the sequences and annotation of the cDNA clones were stored in the database. Further, we constructed an interface that can be used to perform various searches in the database. The PEDE database is the primary resource of expressed pig genes that are supported by full-length cDNA sequences. This resource not only enables us to pick cDNA clones of interest for a particular analysis, but it also confirms and thus contributes to the sequencing integrity of the pig genome, which is now being compiled by an international consortium (). PEDE has therefore evolved into what we now call ‘Pig Expression Data Explorer’.

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