How this brainy fruit fly will save the lives of mice and men

THEY are the curse of mankind, known only for their ability to spread disease and best dispatched with a rolled-up newspaper.

But one of their number, the humble fruit fly, has emerged as an unlikely human ally after Scots scientists devised a remarkable technique for testing drug treatments on the insects.

Using methods that sound more like science fiction than science fact, the researchers have found a way to inject fruit flies with the genes of humans and jellyfish to make them accurate testers for human treatments for Alzheimer's and Parkinson's.

The scientists at Brainwave Discovery Limited say their breakthrough will provide an alternative to experiments on mice, knocking millions of pounds off the drug testing process, and allowing a dramatic increase in the number of pharmaceuticals entering trials.

Although many animal rights protesters will welcome the move away from using laboratory mice in drug testing, some groups last night said that even the use of fruit flies in experiments was "unacceptable" and "bad science".

The method works by isolating a human gene for any disease of the central nervous system, such as Alzheimer's, and injecting it into the embryos of fruit flies. The gene is engineered only to affect a single area of the fly's brain to avoid side effects.

At the same time, scientists inject the embryo with a gene isolated from a species of deep-sea jellyfish that emits flashes of blue and green light so that the infected part of the fly's brain flashes when it is active.

When the flies hatch days later, they look and act like normal flies except for emitting a blue light, only visible under a microscope, from their brains.

The flies are then fed the drug, and if the blue light flashes to green, the drug is working and should be further tested for use in humans. If the brain does not flash, the drug is not effective.

Once scientists have received the "green light" from the first generation of flies, they can make the experiment more sophisticated by adding a further human gene to those flies' offspring, which inherit the human and jellyfish genes of their parents.

Thanks to the short life cycle of the flies, increasingly complex generations of the insects can be developed within months, making drug tests even more sophisticated.

The fruit flies' brains, where the groundbreaking experiments take place, are barely visible to the naked eye as they are less than 0.7mm in diameter. Scientists use a digital microscope that magnifies the fly by 40 times just to see the tiny emissions of light from its brain.

Dr Douglas Armstrong, chief scientific officer of Brainwave Discovery Limited, said: "The advantage of using fruit flies is that we save companies time and money. Fruit flies hatch within days and live for a maximum of 100 days, so it takes just weeks to get results rather than months, as with mice.

"It is very expensive to manufacture tested drugs, so the fact that the flies need only a tiny amount knocks a lot of money off the cost of testing. The flies also need less care in the lab, which is cheaper."

He added: "Testing is the biggest single cost to the pharmaceutical company, running into tens of millions of pounds, so potential new drugs are not tested at all because of the cost.

"We can knock millions of pounds off that initial test and do it very accurately because we can use 100 fruit flies instead of 10 mice."

The breakthrough could also lead to drugs being available to the public quicker than before, as the testing process currently takes 10 to 13 years using mice.

Dr Jean Turner, of the Scottish Patients Association, said: "Anything that means drugs are made available more quickly is a great thing, as long as it's safe. It would be wonderful to have these drugs, but it's not just about speed and cheapness, it's about outcomes and effectiveness."

A spokeswoman for Age Concern Scotland welcomed the technology, and particularly its potential benefits for sufferers of Alzheimer's. She said: "Given the increasing number of older people that live into much older age there is an anticipated rise in the number of older people who will suffer from Alzheimer's and dementia, and it's absolutely essential to concentrate our efforts on new forms of prevention and treatment.

"I am delighted to hear of this advance, but this will take some time to develop and we will see the benefits in years to come, which can be frustrating for people who are concerned about dementia sufferers today. This is good news for the future but there must be a caution on raising expectations for current sufferers and their families."

Although pharmaceutical companies worldwide that are set to invest in the revolutionary technology hope it will transform the controversial image of animal testing, animal rights protesters say they object even to the use of fruit flies.

Fiona Ogg, chief executive of animal rights group Advocates for Animals, said: "The use of any animal is unacceptable and poor science. There is no perfect animal or insect human model.

"An insect with human proteins put into its insect brain is not a little person. Because of species' differences in structure, function and physiology, each species responds differently to drugs and chemicals."

Philip Wright, science director at the Association of the British Pharmaceutical Industry, agreed fruit flies could not solve the problems of drug testing. He said: "Fruit flies are great research tools for certain areas of biology but they are not an effective replacement for mice or other mammals used in the understanding of how a medicine is likely to act in a human.

"Industry is putting a lot of effort into improving animal models and finding alternatives where possible, but these tests cannot replace animal models at the moment."