Biologists Sketch Out DNA Draft




Biologists at the U.S. Department of Energy have gathered raw DNA data sufficient to search for genes on three human chromosomes, Secretary Bill Richardson said Thursday.


The department is a member of the public consortium racing to decode the genome, the DNA molecules in which the human hereditary information is inscribed. The department's Joint Genome Institute, in Walnut, California, has now fulfilled, well ahead of deadline, its quota as part of the consortium's goal of achieving a "rough draft" of the human genome by the end of June.


The consortium's rival, the Celera Corp., said last week that it had already collected all its DNA data and would assemble the pieces into an essentially complete genome within a few weeks.


The rough draft data consists of fairly short pieces of DNA, most of them more than 10,000 units in length, whose approximate position on the chromosomes is known. Although this is a long way from having a complete chromosome, the pieces are still very useful for biologists searching for genes.


The consortium expects to have knitted the pieces of its rough draft together in complete chromosomes by 2003. Celera says it will reach this state in a few months, without going through a rough-draft stage. The company plans to make use of the consortium's data, which is public, as well as its own.


The department biologists have completed a rough draft sequence for chromosomes 5, 16 and 19. Only one chromosome, No. 22, has been fully sequenced and assembled, a task completed in December by the Sanger Centre of England and others. There are 24 human chromosomes, containing some 3 billion units of DNA.


The department supports research in human genetics because of the interest of its nuclear weapons laboratories in radiation effects. Plans to decode the human genome were started at the department, but its role has since been somewhat overshadowed by that of the National Institutes of Health.


Its analysis of the three chromosomes was performed mostly within the last year, using DNA sequencing machines made by Amersham Pharmacia, said Trevor Hawkins, the department's sequencing director.


Hawkins said he would now turn to analyzing the mouse chromosome regions that correspond to human chromosome 19, to produce the first extensive comparison of the two species. The mouse genome is expected to help in interpreting the generally similar human genome.