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Vosshall’s arm offers a pleasing scent to this mosquito, which detects its prey through smell. She aims to block that olfactory system to stop diseases like malaria, which kills up to 1 million people each year.
In 2008, Vosshall’s lab group, which consists of six to nine postdocs and about five graduate students, began to shift its attention to mosquitoes—which explains the socks in the freezer. In 2008 and in subsequent studies in 2011, her group elucidated the first modern scientific explanation for how the popular anti-mosquito compound DEET works—it confuses the insects by jamming their odor receptors. Ultimately, Vosshall says, she hopes to help develop more targeted, more efficient insect repellants, a crucial weapon against mosquito-borne diseases like malaria.
Reaching into her office fridge, Vosshall opens a vial and smells it, then passes it to me. “This is violet,” she says, and I sniff. The smell is luscious and a little heady, almost more food than flower. Reluctantly, I give it back to her. (I probably couldn’t have continued smelling with such pleasure even if I had held on to it; even a strong scent will pretty much disappear when you try to inhale it a second time.)
She opens another vial, sniffs, and visibly shudders. “Gaaaah,” she says. “I didn’t realize what this was. Here, smell.” Foolishly, I sniff the vial that had thoroughly disgusted her. But I can’t smell anything at all. Vosshall seems delighted.
“That’s androstenone,” she tells me. “It’s a component of male sweat, and a small percentage of people are unable to smell it.” Most people are totally grossed out by the scent, she says. Another 15 percent or so find it less disgusting—some even like it, describing it as smelling sort of like vanilla. And within that group is an unknown minority of people who, like me, can’t smell androstenone at all. The key is the gene for the olfactory receptor OR7D4. Vosshall probably has two good copies. I probably have two faulty copies. She’s doing some studies now to test the sensitivity of young women to these odors at the most fertile point in the menstrual cycle. The women sniff from two vials of androstenone in different concentrations, as well as two control vials, while their sweat response and cortisol response are measured. Her “long-term dream,” she says, is to study the effect of OR7D4 and other receptors on general sociability or sexual responsiveness, but these studies are especially difficult to conduct.
"Mainstream was just taboo for Leslie.”
“The only available experiments are very indirect,” she says. Asking a person to sit in a laboratory and smell a sex-related odor and give a rating of how pleasant or unpleasant the scent is, she says, “is very far abstracted from human sexuality and does not really capture the biology well.”
Vosshall discovered OR7D4 with her Rockefeller collaborator Andreas Keller and a team led by Hiroaki Matsunami at Duke University. When they announced their finding of the androstenone-sensing receptor in 2007, there was a little ripple of amazement in the olfactory science world. A Newsweek report referred to some good-natured jealousy among other smell investigators.
Working at the Fringes
“There are some people you meet and you know that they will do something very meaningful in science,” Vosshall’s postdoc advisor Axel told me in a phone conversation laden with superlatives. “She’s really strikingly dynamic, and that’s coupled with experimental fearlessness and thoughtfulness.”
Axel said he is particularly impressed by Vosshall’s perseverance, no matter how many wrong turns she takes along the way. “Leslie is able to enter into new and difficult experimental arenas with the knowledge that it’s going to take a depth of understanding and time to make a meaningful contribution.”
Photo: Leslie Vosshall Lab