BIOLOGY is on the brink of a new era. 快猫短视频s have sequenced nearly all the genes of the fruit fly, and say they will complete the work in the next few months-more than a year ahead of schedule.
The announcement boosts controversial claims by Celera Genomics, the Maryland company that is doing much of the work, that it will completely sequence the human genome by the end of 2001. Craig Venter, head of Celera, hopes the fruit fly success will unite other researchers behind him. 鈥淚鈥檓 optimistic that it will help get a human collaboration get off the ground,鈥� he says.
Complete gene sequences already exist for some simple organisms such as microbes and the worm Caenorhabditis elegans. But the fruit fly Drosophila melanogaster is by far the most complex organism whose genome has been deciphered. For nearly a century, it has been a workhorse for geneticists studying behaviour, disease and development.
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At last week鈥檚 meeting of the American Association for the Advancement of Science in Washington DC, Venter said his team has sequenced 13 601 genes, thought to account for at least 97 per cent of the total. Already, the database has yielded some intriguing insights. It has revealed the elusive fly version of the gene p53, which is often defective in people who have cancer. Of 289 human disease genes the researchers have looked for in the fly sequence, they found close matches for 60 per cent of them-so Drosophila鈥檚 future as a model for human disease looks set to continue.
But Venter is intrigued that nearly half of the fruit fly genes have no known analogue in any organism. 鈥淭hat says there is a lot of biology left to learn,鈥� he says.
To accomplish the feat, Celera joined forces with two publicly funded groups, the Berkeley Drosophila Genome Project (BDGP) and the European Drosophila Genome Project. Celera鈥檚 sequencing factory generated most of the 120-million base pairs that make up the sequences found so far, relying on data and expertise from the academic groups. Its strategy was to sequence random overlapping fragments of the genome, then use computers to piece together the fragments like a huge jigsaw puzzle, a technique that had come up trumps in the race to complete sequences for microbes.
Some experts feared this wouldn鈥檛 work on Drosophila, whose genome is far larger than that of most microbes and peppered with 40-million base pairs of repetitive sequences known as 鈥渏unk DNA鈥�, which does not contain genes. Sceptics thought this would confuse the computer assembly process. Gerald Rubin, who started the BDGP, says doubters warned him against working with Venter using this technique. 鈥淚 told them this was an experiment-we鈥檒l only find out if it works by trying,鈥� he says.
But the gamble has paid off. The team is confident that the remaining unsequenced genes lie in a thousand small gaps, which they expect to close in a few months.
Ed Lewis of Caltech, who was joint winner of a Nobel Prize in 1995 for his pioneering work on Drosophila genetics, says the new fly sequence will change the future of genetics. 鈥淭his is where the field is going. Staring at computer sequences is becoming an increasingly important part of the job.鈥�
Venter says the Drosophila project taught his team valuable lessons it will use to help complete its human genome project. He hopes the success with the fruit fly will convince other research teams to join forces. But many researchers are sceptical that Venter will complete the project before government-funded groups. Our genome is almost 20 times the size of the fruit fly鈥檚, and contains far more junk DNA, so it remains unclear if the Celera technique will succeed.
