Fruit Flies Smell Deuterium

Then surprise here is that itappears that a fruit fly is able to detect the difference in vibration energyby isotopes of hydrogen at least and is suggestive that larger isotopes mayalso be detected.

How about developing fruit fliesable to collect specific atoms or selected isotopic molecules?  It may well be superior to a centrifuge.

Probably too much effort and not particularlyeasy, but it is an independent route.

Collecting tritium could beimportant, though density is possibly way too low.

Fruit flies can detect heavy hydrogen: study

February 16, 2011 by Lin Edwards

http://www.physorg.com/news/2011-02-fruit-flies-heavy-hydrogen.html

In the present study wild types of different origin were shown to bequite different in their behavior towards odors of different origin. Credit:Rickard Ignell

(PhysOrg.com) -- A new study by researchers in Greece and the US has found that fruit flies candiscriminate between normal and heavy hydrogen (deuterium) isotopes, which addsweight to a new theory of how the sense of smell works.

Dr Efthimios Skoulakis of the Alexander Fleming Biomedical SciencesResearch Center in Vari, Greeceand colleagues presented fruitflies(Drosophila melanogaster) with acetophenone, an odorant molecule oftenused in perfumes, in a T-shaped maze. In one branch the molecule containednormal hydrogen, while in the other the hydrogen atoms inthe molecule were replaced by deuterium. The flies were able to choose thebranch they preferred.

The fruit flies, which are known to have a strong sense of smell,showed a definite preference for the molecule with more hydrogen and theiraversion to the deuterated molecule grew as more hydrogens were replaced. Whenfruit flies that had been genetically modified to have no sense of smell wereused, they showed no preference.

The fruit flies’ ability to discriminate between the molecules was alsodemonstrated by successfully giving the flies mild electric shocks to theirfeet as they walked on the floor of the maze to condition them to selectivelyavoid either form of the molecule.

Dr Skoulakis said the results support a new theory of olfaction firstproposed in 1996 by co-author Dr Luca Turin, a biophysicist who is now at theMassachusetts Institute of Technology in Cambridge in the US. The new theorysuggests odorants are detected by their vibrations rather than by their shape.

Deuterium differs from the normal isotope of hydrogen in that itsnucleus contains a proton and a neutron instead of just a proton. This roughlydoubles the mass of the deuterium atom, and so while it has similar propertiesto normal hydrogen, the larger mass means bonds between deuterium and otheratoms within molecules vibrate more slowly.

The leading theory of how smell works is that odorant molecules are detectedby receptor proteins in the olfactory membranes because of their shape, whichfits into the shape of a cavity in the protein, like a key in a lock. If themolecule fits a signal is sent to the brain.

Dr Turin’s theory is that the electrons of the odorant might be ableto cross a receptor membrane only if the bonds in the molecule are vibrating atexactly the right frequency.

 Since an odorant with normalhydrogen will have different vibrational properties to the deuterated odorant,the two odorants should smell different even though their shape is the same.

As further confirmation the researchers tested the fruit flies withnitriles, which have a similar vibrational frequencies to that ofdeuterium-carbon bonds. The fruit flies had an aversion to the nitriles asexpected.

Humans have not been shown to have the ability to discriminate betweencompounds containing normal and heavy hydrogen, but Dr Turin saidthere were unpublished reports of a similar ability in at least one dog, whichignores an odorant it is trained to detect if the molecule is deuterated.

The paper is published in the journal Proceedings of the National Academy of Sciences (PNAS).

More information: Molecular vibration-sensing component inDrosophila melanogaster olfaction, PNAS, Published online before printFebruary 14, 2011,

 doi:10.1073/pnas.1012293108