PT  - JOURNAL ARTICLE
AU  - Klio Maniati
AU  - Katherine-Joanne Haralambous
AU  - Luca Turin
AU  - Efthimios M C Skoulakis
TI  - Vibrational Detection of Odorant Functional Groups by Drosophila Melanogaster.
AID  - 10.1523/ENEURO.0049-17.2017
DP  - 2017 Oct 26
TA  - eneuro
PG  - ENEURO.0049-17.2017
4099  - http://www.eneuro.org/content/early/2017/10/26/ENEURO.0049-17.2017.short
4100  - http://www.eneuro.org/content/early/2017/10/26/ENEURO.0049-17.2017.full
AB  - A remarkable feature of olfaction, and perhaps the hardest one to explain by shape-based molecular recognition, is the ability to detect the presence of functional groups in odorants, irrespective of molecular context. We previously showed that Drosophila trained to avoid deuterated odorants could respond to a molecule bearing a nitrile group, which shares the vibrational stretch frequency with the CD bond. Here we reproduce and extend this finding by showing analogous olfactory responses of Drosophila to the chemically vastly different functional groups, thiols and boranes, that nevertheless possess a common vibration at 2600 cm-1. Furthermore, we show that Drosophila do not respond to a cyanohydrin structure that renders nitrile groups invisible to IR spectroscopy. We argue that the response of Drosophila to these odorants which parallels their perception in humans, supports the hypothesis that odor character is encoded in odorant molecular vibrations, not in the specific shape-based activation pattern of receptors.Significance Statement To gain mechanistic insights we address predictions of vibrational olfaction in Drosophila. We show for the first time that Drosophila respond to vibrational frequencies characterizing functional groups. Boranes (-BH) and thiols vibrate at the same frequency and flies respond to boranes as if they were thiols strongly suggesting that functional groups of similar enough vibrational frequencies have similar odor character in Drosophila. In accord with theoretical predictions, although flies readily detect nitriles, they fail to respond to nitrile groups in molecular configurations that render them undetectable to infrared spectroscopy. We conclude that the behavioral response of Drosophila to these odorant functional groups is consistent with the notion that their character is encoded in their molecular vibrations.