Stripping Down Science by Chris Smith, Dr Christorpher Smith

wood, but the treatment wasn’t harsh enough. Instead, it seems Stradivari, or the carpenter who supplied him, must have resorted to chemical means, probably in the form of copper and iron salts, which are strongly oxidising and could conceivably have damaged the wood in this way. To find out exactly what chemicals they must have used will require access to more wood fragments, which could take some time. ‘These samples are hard to get,’ Nagyvary says. ‘You cannot approach Itzhak Perlman and ask him to give you a chunk of his Stradivarius for analysis.’
    But why chemically massacre your future instrument anyway? Nagyvary thinks the answer is all down to a primitive attempt at preservation. ‘I am a heretic in this regard. I really don’t think that Stradivari did this for acoustical purposes. I think that was a rather routine process around that time, in Cremona, where most woodworkershad to preserve their wood against the woodworm. Stradivari was a marvellous craftsman,’ Nagyvary observes, ‘but the magnificent sound of his instruments is a lucky accident.’

You’re having me on! I hear you exclaim. But no, mad as this might sound, it’s no myth. With the magic of modern science it’s possible to give a laboratory fruit fly the smelling ability of a mosquito, which is exactly what a group of scientists did recently to work out how these bloodthirsty winged menaces hunt us down for dinner.
    Mosquitoes are universally acknowledged as the most dangerous animals on earth owing to the number of deaths they cause by spreading diseases like malaria, dengue and yellow fever, which together run to hundreds of millions of cases per year. Scientists and doctors are therefore very eager to track down how it is that mosquitoeshome in on us, and what attracts them to humans in the first place, because if we can understand how they’re doing this then we can come up with better repellents. At the moment, substances like DEET (diethyl toluamide) are produced by chemical trial and error, but by knowing exactly how a mosquito identifies its next meal, it ought to be possible to produce more macho molecules tailor-made to turn a hungry mosquito into an anorexic.
    Fundamental to the mosquito’s human-tracking ability is its olfactory arsenal. The antennae that project from its head are covered in receptor molecules, which resemble miniature chemical docking stations that are each wired up to an individual nerve that connects to the animal’s brain. Different types of receptors are specialised for picking up different types of odour molecules, which tend to have specific chemical shapes or structures. So when one of these odour chemicals bumps into a receptor that is the right shape to recognise it, the receptor is activated and fires off impulses down the adjacent nerve, signalling a ‘hit’. The brain then adds together all of the incoming information to build up a picture of what the world smells like and from whichdirection certain odours are arriving.
    This sounds simple enough but, by studying the mosquito genome, scientists have found the genetic recipes for more than 70 of these different receptors. They’ve also found that many odour chemicals can activate more than one type of receptor at once, which makes it very difficult to understand exactly which odours are detected by which receptors and therefore how to make an insect repellent to best block them.
    Now enter Yale researcher Allison Carey. 43 Using a family of mutant fruit flies in which one of the groups of nerves in their antennae are devoid of odorant receptors, she added to these anosmic neurons, one at a time, the genes for 72 different mosquito odorant receptors. This was the molecular equivalent of stitching a dog’s nose onto a human, because it bestowed on the resulting flies the ability to smell whatever chemicals each of the individual genes normally enable mosquitoes to detect. By