Insect sensors in "Chemistry World"

Chemistry World
Vol.3, No.7
July 2006 pp.26-30
(c) Royal Society of Chemistry

Insect detectives
John Bonner

"The powerful sense of smell that insects possess is being put to use in applications from detecting rotten tomatoes to controlling one of the deadliest of diseases in Africa"

http://www.rsc.org/chemistryworld/Issues/2006/July/InsectDetectives.asp

"‘Biological systems have sensitivities several orders of magnitude higher than the best artificial noses that we have developed. A gas chromatograph/mass spectrometer (GC–MS) will be able to detect compounds at the nanomolar or picomolar level but an organism may respond to some compounds found at femtomolar concentrations. It all depends on how important that compound is to the animal,’ explains John Pickett, head of the [Rothamsted] lab’s biological chemistry division.

"The odorant molecule passes through pores in the outer cuticle of the sensillum and becomes attached to an odorant binding protein (OBP). This protein carries the hydrophobic ligand through the lymph fluid found inside the cell and attaches it to a receptor on the dendritic projections of a sensory nerve cell. The initial signal from this receptor to the central nervous system is amplified by the activation of the G protein pathway that is a common feature of signal transduction systems in all living organisms.

"However, the position of the insect olfactory organs on the surface of its body allows them to be investigated using methods which would be ethically unacceptable in vertebrates.

"A technique developed by German biologist Dietrich Schneider in the 1950s enables researchers to make direct recordings of activity in insect olfactory nerves and identify the specific plant or animal-derived compounds that trigger a behavioural response. "

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Previously known as "Chemistry in Britain"
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