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A single sequencing read of a few hundred cDNA bases usually is sufficient to serve as a distinguishing identifier (EST) of the predecessor mRNA. This approach was pioneered by J. Craig Venter, now director of The Institute for Genomic Research, which made public a major EST data release in June 1997. High-throughput production of ESTs from I.M.A.G.E. cDNAs has been funded predominantly by Merck & Co., with sequencing at the Washington University (St. Louis) Genome Center Human EST Project. ESTs are deposited in the public database dbEST, which supports queries on the similarities of ESTs and cDNAs to cDNA molecules whose analysis is just beginning. The I.M.A.G.E. consortium manages the distribution of reference sets of cDNAs. In the United States, libraries of cDNA clones representing many different tissues are donated to I.M.A.G.E. at LLNL, where the clones are placed into reference arrays; replicas are provided to genome research centers and private-sector resource distributors. Over 3 million clone replicas have been sent to more than 1000 laboratories worldwide; the end users analyze the clones and return data on them. All data is entered into public databases, enabling researchers to compare it with their preliminary cDNA sequencing data and eliminate redundant efforts. EST analyses of over 500,000 cDNA I.M.A.G.E. clones suggest that more than 50,000 of the estimated 60,000 to 80,000 human genes are represented. I.M.A.G.E. researchers at LLNL are providing subtracting cDNA reagents to aid the production of new cDNA libraries by Bento Soares that preferentially contain clones not already represented in the current I.M.A.G.E. collection. |
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