[transgendernews] [Science] [USA] Gene determines whether male body odor smells pleasant
Stephanie Stevens
PhysOrg.com, USA
Published: 13:20 EST, September 16, 2007
Gene determines whether male body odor smells pleasant
To many, urine smells like urine and vanilla smells like vanilla. But
androstenone, a derivative of testosterone that is a potent ingredient
in male body odor, can smell like either - depending on your genes.
While many people perceive a foul odor from androstenone, usually that
of stale urine or strong sweat, others find the scent sweet and
pleasant. Still others cannot smell it at all.
New research from Rockefeller University, performed in collaboration
with scientists at Duke University in North Carolina, reveals for the
first time that this extreme variability in people's perception of
androstenone is due in large part to genetic variations in a single
odorant receptor called OR7D4. The research is reported September 16
as an advance online publication of the journal Nature.
Androstenone, found in higher concentrations in the urine and sweat of
men than of women, is used by some mammals to convey social and sexual
information, and the ability to perceive androstenone's scent may have
far-reaching behavioral implications for humans.
In the largest study ever conducted of its kind, researchers at
Rockefeller University presented nearly 400 participants with 66 odors
at two different concentrations and asked them to rate the
pleasantness and intensity of each odor. When scientists at Duke
University identified OR7D4 as a receptor that androstenone
selectively activates, Leslie Vosshall, Chemers Family Associate
Professor and head of the Laboratory of Neurogenetics and Behavior at
Rockefeller University and Andreas Keller, a postdoc in her lab,
formed a collaboration with them, and began collecting blood samples
from participants and isolated their DNA. The Duke team, led by
Hiroaki Matsunami, used DNA from each participant to sequence the gene
that encodes the OR7D4 receptor.
"With this large dataset, we are able to say that people who express
different variants of this receptor perceive this odor differently,"
says Vosshall.
Although it has long been suspected that the ability to perceive the
odor of androstenone is genetically determined, this study is the
first to identify variations in a single gene that account for a large
part of why people perceive androstenone's scent so differently.
With their Duke collaborators, Vosshall and Keller identified two
point mutations called single nucleotide polymorphisms along the gene,
which gave rise to two variants of the odorant receptor: RT and WM,
which differ by two amino acids. As a group, participants with the
RT/RT genotype perceive androstenone's odor as foul and intense. Those
with the RT/WM genotype, on the other hand, are more likely to
perceive androstenone as less unpleasant. Many cannot smell
androstenone at all. Although some participants with the RT/WM
genotype can smell androstenone, they experience the smell very
differently than those with two copies of the fully functional
receptor: To them, androstenone doesn't smell like urine; it has a
vanilla scent.
"There are two independent things that are interesting about this
odor," says first co-author Keller. "One is that it is a potential
social signal but the other one is that so many people cannot smell
it."
Two additional point mutations in some of the participants influenced
their sensitivity to androstenone, one of which may make humans
hypersensitive to this odor. Vosshall and Keller are interested in
what it is about these amino acid changes that alter one's perception
of androstenone's scent, and in whether one's perception of this
potent compound can influence behavior.
"Since some mammals clearly use androstenone to communicate sexuality
and dominance within a social hierarchy, it's intriguing to think
whether the same thing may happen in humans," Vosshall says. "If so,
what happens to humans who can't get the signal because they have the
nonfunctional copy of the gene? Or the hyperfunctional one? What could
be the social and sexual implications of this on one's perception of
the smell of fellow humans?"
Source: Rockefeller University
(c) PhysOrg.com 2003-2007
http://www.physorg.com/news109167619.html
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h/t BLS R af D
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