Smell this!

Great lectures by great scientists always inspire me, no matter what the subject matter is. It's even better if it's as far as possible from macrophage biology. Who wants to look at and study a certain cell day in and day out and then go listen to more lectures about them after a 12 hour day in the lab? Instead, I went to listen to talk given by Leslie Vosshall as a part of the Harvey Society Lectures at Rockefeller.

These lectures happen every month and there is always an email advertising them - even hors'dourves and wine beforehand - but I have never made it there before. Since it's Rockefeller, they usually invite pretty well known scientists to talk. The reason I got interested this month was that about a year ago, I participated in a clinical research study. At the time I was quite broke and was looking for any way to make money (well, other than selling my body) which, around 3 major universities and hospitals, is not so difficult: I can always participate in clinical studies. I saw some fliers around campus for this "smell study" and it seemed simple enough: you just go and smell different odors, they ask you questions about them and you get $40 per session. Not bad. So I enrolled, went once a month for about 4 months, it was the typical research study set up, drawing blood and filling out pages and pages of forms, etc. I always had to smell two different odors: by the end of the 4 months, I realized they were vanilla and sweat (I kept asking the study coordinator but she wasn't supposed to tell due to the design of the study). In any case, it was not the most pleasant thing, smelling vial after vial of sweaty odor and trying to decide which vial had the higher concentration (or something along those lines, the exact details escape me, it seemed rather boring at the time).

Turns out, on the contrary, it's rather fascinating! But I don't wanna get ahead of myself. First of all, these Harvey lectures are not just like any old science lecture. There was a group of people, all sitting in the first row, wearing very fancy suits and gowns. Apparently, the big shots in the society take the speaker out for a fancy dinner before the lecture and from what I had heard and what I could tell, there is no shortage of wine at this party. In fact, the speaker is encouraged to drink since the lecture is more informal - despite the formal outfits - and more directed towards a general audience. Leslie Vosshall seemed a little drunk by the time she took the stage. She was young - just googled her and she's in her mid 40's but I was guessing mid to late 30s actually - charismatic, funny and an amazing speaker. Ah, so nice to hear a good speaker talk about science!

As I found out, a big issue in smell biology is that humans vary hugely in how intense and/or pleasant they perceive certain odors. One of these smells is androstenone an odorous steroid derived from testosterone (this is where the sweaty smell comes in the picture; when testosterone is broken down, this substance leaves the male body in sweat) which is variously perceived by different individuals as offensive (‘‘sweaty, urinous’’), pleasant (‘‘sweet, floral’’) or odorless. It's really interesting because we only have somewhere between 300 and 400 odor receptors in our noses and yet we can differentiate between very subtle differences in smells and can learn an almost infinite number of new smells during our lifetime. What's truly amazing about the study Vosshall had done is that she and her lab actually found which receptor is responsible for smelling androstenone and found a common genetic variation (two amino acid substitutions in the receptor) among the study subjects enrolled in the study which accounts for the differences in perception of this odor.

I think that even if you're not a scientist, it's easy to appreciate how cool this is! We start with a common observation: people perceive certain smells differently. This is usually attributed to cultural differences - my roommate, who grew up in India, for example, loves the taste and smell, which are tightly connected, of anything with chillies, while I am frightened by the smell alone - but here is this receptor in our noses that we now know is responsible for smelling or not smelling male sweat! Amazing! It's worth taking a look at the paper (sited on the bottom of this post).

Another interesting fact that also came out of this study: women have a statistically significantly better smell (I always thought it was the other way around) and smoking is really bad for your sense of smell - so if you're a smoking man, you're screwed!

Unrelated to the human smell study, Vosshall also studies insect smell, which is really important because female mosquitoes that carry dangerous diseases such as yellow fever and malaria, are attracted to humans: there is some sort of odor that they are sensitive to and this is what insect repellents use to try to block this attraction. It turns out that "Deet", which has been used since the 50's as pretty much the only insect repellent, has been reported to be a neurological toxin and you have to put it on your skin in ridiculously high concentrations (1 molar!). From the unpublished data that she showed last night, it seemed to me, that at least in vitro (in the test tube) they had discovered a far better insect repellent compound. Um, yea, if you search her name on pubmed, you can see that she had published 4 articles in Nature in 2007. Holy shit!

After the talk, there was an appreciation speech by Vosshall's previous mentor at Columbia, Richard Axel (a Noble Price winner, by the way), also very cool! I love Immunology, but I do have a soft spot for Neuroscience!

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Andreas Keller, Hanyi Zhuang, Qiuyi Chi, Leslie B. Vosshall & Hiroaki Matsunami. Genetic variation in a human odorant receptor alters odour perception. Nature 449:468-472 (2007).
http://www.nature.com/nature/journal/v449/n7161/full/nature06162.html