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Dr Matthew Freeman
This is fundamental to the medical research of the future
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The BBC's Sue Nelson
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Under the microscope
A close-up view of the fruit fly
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Thursday, 23 March, 2000, 19:00 GMT
Comparing flies with humans
Scientists are already using the genome data
By BBC News Online science editor Dr David Whitehouse

Scientists are already mining the rich data set that is the fruit fly genome.

It is a quest that will benefit medicine and enhance our understanding of the nature of life itself.

Worm BBC
The fruit fly overtakes the worm as the most complex organism yet decoded
There is new information on the way cells die; on the way nerves develop and transmit signals in between cells; on the way DNA is repaired in cells. There is information about how infection attacks the body and how cells develop and how cancer starts.

These are just some of the scientific spin-offs from sequencing the genome of the fruit fly Drosophila melanogaster.

Humans and fruit flies are closely related. Of the fly's 13,601 genes, scientists believe that possibly two-thirds may have counterparts in humans. If we understand how these genes work in the fruit fly then we gain understanding about how they work in ourselves.

No wonder the fruit fly has become the classic lab model.

Blood diseases

Even the differences are illuminating. Fruit flies have no lungs. They absorb oxygen from the atmosphere through holes in their sides. This has resulted in the insect evolving a particular kind of haemoglobin, the oxygen-carrying molecule in its bloodstream.

Studying fly eyes can give us clues about cancer
This haemoglobin molecule is not susceptible to the same diseases and defects such as those that cause thalassaemia in humans. Understanding why the blood of a fruit fly works this way may just help us understand why humans develop the blood diseases they do.

Cancer is another area that may benefit. It appears that about 70% of known cancer-causing genes in humans are present in the fruit fly genome.

Knocking them out one by one to see what effect it has on the fruit fly will be illuminating.

Flies do not have lungs like humans
Fruit flies have some of the genes that in humans are involved in Parkinson's and Alzheimer's disease. But as far as we know, the fruit fly does not suffer from these ailments. So why does it have these genes and what do they do?

However, it is not just when things go wrong that science can benefit.

It is clear that humans and fruit flies share the same basic core molecular machinery. Now that we know the fruit fly genetic blueprint, we will be able to carry out experiments to investigate how these creatures function at the most fundamental level.

Gene combinations

Such experiments, like knocking out a key gene, would be unethical to perform on humans but very practical and easy to do with fruit flies. We can investigate the effects of single genes, and combinations of genes that control whole chemical pathways. It will be a revolution.

The fruit fly is the third major type of organism to have its genetic code sequenced after yeast and the soil worm Caenorhabditis elegans. The human genome is nearing completion and scientists are enthralled at the contrasts and comparisons that can be made between these lifeforms.

Their genomes show just how closely related are all living things on Earth. Although the last common ancestor of humans, fruit flies, worms and yeast lived over a billion years ago, there are still many genes we share that betray our common heritage.

About 30% of fruit fly genes crop up in C. elegans and 20% of fly genes can be found in yeast.

Scientists sense mystery in the vast tracts of genes and DNA that have unknown functions. Many of them play an essential role in life that we do not yet realise. So it is with the 180m base pairs of the fruit fly genome. It is a new world.

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See also:

23 Mar 00 | Sci/Tech
Small fly makes history
18 Feb 00 | Washington 2000
Fruit fly gene success
05 Jul 99 | Sci/Tech
Similarity in diversity
10 Dec 98 | Sci/Tech
Small worm makes history
03 Dec 99 | Sci/Tech
Book of life: Chapter one
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