Fruit fly gene success

We have much in common with the fruit fly

Scientists have unravelled virtually the entire genetic code of the fruit fly (Drosophila melanogaster). The work will be enormously helpful in figuring out the more complex genome of humans.

The scientists behind the collaborative effort are likely to publish their results next month - 18 months ahead of the initial schedule.

I would still put money on the publicly-funded HGP to produce the biologically important information before Celera

Dr Peter Little, Imperial College

The project was discussed at the American Association for the Advancement of Science's (AAAS) annual meeting, currently taking place in Washington DC.

The researchers said they had deciphered more than 97% of the fly's genetic code and more than 99% of the actual genes. In all, it turns out that every fruit fly cell contains 13,601 genes. Human cells, by contrast, are thought to have more 70,000 genes.

The achievement is being widely hailed as a dramatic and important development in science - it is the most complex organism yet to have its genome decoded.

But while some believe it proves that the technology used to decode the genome is effective, others believe that unravelling the human DNA sequence will be much more difficult.

Human connection

Fruit flies share nearly 60% of human genes and are studied by thousands of scientists around the world. The reason is that fruit flies and humans use the same or similar genes to develop into adults. And the short life cycle of the fly makes it an ideal subject for genetic experiments.

Rubin: Celera speeded things up

Professor Gerry Rubin, from the University Of California, Berkeley, worked with the Celera Genomics Corporation to decipher the fruit fly's DNA sequence: "They can become addicted to alcohol, cocaine and other drugs. They have a wake-sleep cycle like humans do. They have complicated rituals of behaviour.

"So in many ways they're really fully functional animals with a brain and behaviour, in addition to sharing many of the biochemical pathways humans have."

Professor Rubin set up the Berkeley Drosophila Genome Project Group in 1992. Since then, he has been sequencing the entire genetic blueprint. The information can be accessed on the internet by scientists, and Dr Matthew Freeman, at the Medical Research Council in Cambridge, UK, has been making practical use of the information. He studies flies with disrupted eyes.

"It turned out that the molecules causing these problems in fruit flies were the same molecules that we know were responsible for causing cancer in humans. So our research in something as bizarre-sounding as a fruit fly's eyes leads to an understanding of the molecules that cause cancer in humans."

Soil worm

Decoding an organism's genome is time-consuming but the technology used is becoming faster and faster. The soil worm Caenorhabditis elegans took eight years to decode, but the more complicated fruit fly has been completed in the same time.

The race is now on to decode other organisms

This is partly due to the intervention of Dr Craig Venter, the entrepreneur head of Celera Genomics. He has antagonised some fellow scientists by patenting pieces of genetic code with commercial value. But the combination of Dr Venter's fast-decoding technology and Professor Rubin's carefully-compiled fruit fly database has been a success for both of them.

"Working with Craig Venter and his colleagues at Celera has allowed us to complete the project 18 months earlier and probably saved the US tax payer $10 million," Professor Rubin told the BBC.

Dr Peter Little is a molecular biologist at Imperial College, London, UK. He agrees that the complete sequencing of the fruit fly genome is significant and useful.

He said: "It is a dramatic and important achievement and provides a very powerful way of developing hypotheses which can then be tested in humans."

Gene race

However, Dr Little disagrees that this means that Celera is sure to win the race to complete the human genome, beating the publicly-funded Human Genome Project.

"You have to understand that the fly genome is 10 times smaller than the human genome, and is also simpler. In humans, the same sequence is found over and over again - it's the most ghastly mess, but the fly isn't."

This small soil worm showed the way

He believes the fly genome could help Celera by allowing them to gain early experience in seeing what genes look like among the long strands of human DNA.

"But we won't know until very late in their project - their method does everything at once, whereas the HGP does things in steps, looking in great detail," he said.

He added: "If I was a betting man, and I am, I would still put money on the publicly-funded HGP to produce the biologically-important information before Celera."