Researchers have found the first molecular clues about how a group of poorly understood chemical signals, called pheromones, enable mice to distinguish male from female.
In knocking out a gene for a pheromone receptor in mice, the researchers discovered that pheromones appear important for gender recognition. Not only did the knockout mice lack aggression toward other males, because they didn't recognize them as males, they readily attempted to mate with both males and females, said senior author Catherine Dulac, a Howard Hughes Medical Institute investigator at Harvard University.
The findings by Dulac and colleagues at Harvard were published online January 31, 2002, in Science Express, which provides rapid electronic publication of select articles that will appear in the journal Science.
Dulac and her colleagues have a longstanding interest in the vomeronasal organ (VNO), a chemical-sensing structure found in the nasal cavities of many animals that is anatomically and functionally distinct from the olfactory system. The VNO, which possesses receptors that respond to secreted pheromones, is wired to a different part of the brain than the olfactory system.
"It had been widely believed that the VNO controlled both mating and aggression, such that when the animal received one type of pheromone, it induced mating and another induced aggression," said Dulac. To better understand the VNO, the scientists produced knockout mice that lacked an important ion channel thought to mediate pheromone signaling in the VNO, called TRP2. Previous studies revealed that TRP2 is found exclusively in the VNO.
"To our great surprise -- and, at first, disappointment -- we found that these knockout males were perfectly able to mate with females," said Dulac. To understand why this was happening, co-authors Markus Meister and Timothy Holy performed electrophysiological s
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Contact: Jim Keeley
keeleyj@hhmi.org
301-215-8858
Howard Hughes Medical Institute
31-Jan-2002