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Human DNA much more complicated then expected.
The ENCyclopedia Of DNA Elements (ENCODE), an international research consortium organised by the National Human Genome Research Institute (NHGRI), part of the National Institutes of Health (NIH), today published the results of its exhaustive, four-year effort to build a "parts list" of all biologically functional elements in 1 percent of the human genome in the journal Nature.The ENCODE consortium's major findings include the discovery that the majority of human DNA is transcribed into RNA and that these transcripts extensively overlap one another. This broad pattern of transcription challenges the long-standing view that the human genome consists of a small set of discrete genes, along with a vast amount of "junk" DNA that is not biologically active. The new data indicate that the genome contains very little unused sequences; genes are just one of many types of DNA sequences that have a functional impact. The consortium identified many previously unrecognized start sites for transcription and new regulatory sequences that contrary to traditional views are located not only upstream but also downstream of transcription start sites. Other surprises in the ENCODE data have major implications for our understanding of the evolution of genomes. Until recently, researchers had thought that most DNA sequences with important biological function would be constrained by evolution making them likely to be conserved as species evolve. But about half of the functional elements in the human genome do not appear to have been constrained during evolution, suggesting that many species' genomes contain a pool of functional elements that provide no specific benefits in terms of survival or reproduction. Over the next couple of years the ENCODE project will be scaled up to the entire genome. The Ensembl project, a joint EMBL-EBI and Sanger Institute project, jointly headed by Ewan Birney, has already generated some initial genome wide datasets with early full scale datasets. This integration has lead to the identification of just over 110,000 regulatory elements across the human genome. "The goal for the next five years is delivering a more complete understanding across our genome" said Birney, "the ENCODE pilot project is the first step towards this goal." Posted by: 3dc 2007-06-16 |
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