Ultra-high olfactory sensitivity for the human sperm-attractant aromatic aldehyde bourgeonal in CD-1 mice

Recent studies have shown that certain aromatic aldehydes are ligands for olfactory receptors expressed in mammalian sperm cells and induce sperm chemotaxis. Using a conditioning paradigm, the olfactory sensitivity of five CD-1 mice for seven aromatic aldehydes was investigated. With all seven stimuli, the mice discriminated concentrations as low as 0.01 ppm (parts per million) from the solvent, and with bourgeonal the animals even detected concentrations as low as 0.1 ppq (parts per quadrillion) which constitutes the lowest olfactory detection threshold value reported in this species so far. The presence of a tertiary butyl group in para-position (relative to the functional aldehyde group) combined with a lack of an additional alkyl group next to the functional aldehyde group may be responsible for the extraordinary sensitivity of the mice for bourgeonal.