Honeybees (Apis mellifera) learn to discriminate the smell of organic compounds from their respective deuterated isotopomers.
The understanding of physiological and molecular processes underlying the sense of smell has made considerable progress during the past three decades, revealing the cascade of molecular steps that lead to the activation of olfactory receptor (OR) neurons. However, the mode of primary interaction of odorant molecules with the OR proteins within the sensory cells is still enigmatic. Two different concepts try to explain these interactions: the 'odotope hypothesis' suggests that OR proteins recognize structural aspects of the odorant molecule, whereas the 'vibration hypothesis' proposes that intra-molecular vibrations are the basis for the recognition of the odorant by the receptor protein. The vibration hypothesis predicts that OR proteins should be able to discriminate compounds containing deuterium from their common counterparts which contain hydrogen instead of deuterium. This study tests this prediction in honeybees (Apis mellifera) using the proboscis extension reflex learning in a differential conditioning paradigm. Rewarding one odour (e.g. a deuterated compound) with sucrose and not rewarding the respective analogue (e.g. hydrogen-based odorant) shows that honeybees readily learn to discriminate hydrogen-based odorants from their deuterated counterparts and supports the idea that intra-molecular vibrations may contribute to odour discrimination.
Department of Neuroscience, University of Arizona, , Tucson, AZ 85721, USA, Graduate Interdisciplinary Programe in Neuroscience, University of Arizona, , Tucson, AZ 85721, USA, Department of Entomology, University of Arizona, , Tucson, AZ 85721, USA, Department of Ecology and Evolutionary Biology, University of Arizona, , Tucson, AZ 85721, USA.
Wulfila
W
Gronenberg
Ajay
A
Raikhelkar
Eric
E
Abshire
Jennifer
J
Stevens
Eric
E
Epstein
Karin
K
Loyola
Michael
M
Rauscher
Stephen
S
Buchmann
D000818:Animals; D001516:Bees / Q000502:physiology*; D003214:Conditioning, Classical; D007858:Learning; D009812:Odorants; D012903:Smell; D055549:Volatile Organic Compounds / Q000737:chemistry*
D055549:Volatile Organic Compounds
differential conditioning; proboscis extension reflex; vibration hypothesis of olfaction