Musk odorants are used widely in cosmetic industries because of their fascinating animalic scent. However, how this aroma is perceived in the mammalian olfactory system remains a great mystery. Here, we show that muscone, one musk odor secreted by various animals from stink glands, activates a few glomeruli clustered in a neuroanatomically unique anteromedial olfactory bulb. The muscone-responsive glomeruli are highly specific to macrocyclic ketones; interestingly, other synthetic musk odorants with nitro or polycyclic moieties or ester bonds activate distinct but nearby glomeruli. Anterodorsal bulbar lesions cause muscone anosmia, suggesting that this region is involved in muscone perception. Finally, we identified the mouse olfactory receptor, MOR215-1, that was a specific muscone receptor expressed by neurons innervating the muscone-responsive anteromedial glomeruli and also the human muscone receptor, OR5AN1. The current study documents the olfactory neural pathway in mice that senses and transmits musk signals from receptor to brain.

Musk odors have been used widely for fragrance and medicine for Ͼ2000 years because of their fascinating scent and physiological effects. Therefore, fragrance manufacturers have been eager to develop high-quality musk compounds that are safe and easily synthesized. We recently identified muscone-responsive olfactory receptors (ORs) MOR215-1 and OR5AN1 in mice and humans, respectively (Shirasu et al., 2014). In this study, we identified musk ORs that are evolutionarily closely related to MOR215-1 or OR5AN1 in various primates and investigated structure-activity relationships for various musk odorants and related compounds. We found that each species has one or two functional musk ORs that exhibit specific ligand spectra to musk compounds. Some of them, including the human OR5AN1, responded to nitro musks with chemical properties distinct from muscone. The ligand specificity of OR5AN1 reflects the perception of musk odors in humans. Genetic deletion of MOR215-1 in mice resulted in drastic reduction of sensitivity to muscone, suggesting that MOR215-1 plays a critical role in muscone perception. Therefore, the current study reveals a clear link between the identified OR and muscone perception. Moreover, the strategy established for screening ligands for the muscone OR may facilitate the development of novel and commercially useful musk odors.

We report the identification of a physiological receptor-volatile pair in the mouse olfactory system. By activity-guided fractionation of exocrine gland extracts and subsequent chemical analysis, (Z)-5-tetradecen-1-ol was identified as a natural ligand for a mouse odorant receptor. (Z)-5-tetradecen-1-ol is excreted into male mouse urine under androgen control and enhances urine attractiveness to female mice. This report is to our knowledge the first to describe natural product-based deorphanization of an odorant receptor.

A laser micromanipulation is suitable for manipulation of a microscopic object suspended in the liquid. Here we proposed the synchronized laser micromanipulation (SLM) for the trajectory control of the multiple targets with each designed trajectories independently by the single laser. SLM is different from the existing laser scanning micromanipulation in that we can manipulate multiple targets independently by the single laser by changing discrete laser scanning pattern. Here we show the condition for stable transportation of targets depends on the effect of Brownian motion. Accordingly we can manipulate multiple microbeads stably along with each designed trajectories by the proposed method.

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