Seen in a recent issue of Science: Loss of Sex Discrimination and Male-Male Aggression in Mice Deficient for TRP2, Stowers et al. (10.1126/science.1069259 (Science Express Research Articles))
Abstract: The mouse vomeronasal organ (VNO) is thought to mediate social behaviors and neuroendocrine changes elicited by pheromonal cues. The molecular mechanisms of the sensory response to pheromones and the behavioral repertoire induced through the VNO are not fully characterized. Using the tools of mouse genetics and multielectrode recording, we demonstrate here that the sensory activation of VNO neurons requires TRP2, a putative ion channel of the transient receptor potential family that is expressed exclusively in these neurons. Moreover, we show that male mice deficient in TRP2 expression fail to display male-male aggression and they initiate sexual and courtship behaviors toward both males and females. Our study suggests that, in the mouse, sensory activation of the VNO is essential for sex discrimination of conspecifics and thus ensures gender-specific behavior. --------- Whew. The following excerpts from the News of the Week are more comprehensible, at least to me: -------- When in Doubt, Mice Mate Rather Than Hate Mary Beckman (Science Feb 1 2002: 782) A new genetically modified mouse abides by the motto of the psychedelic age: Make Love, Not War. A male that can't sniff out the sex of its partner will, to put it delicately, try to partner with it rather than attack it. The same mutation could never lead to a peaceable kingdom among humans, however, because the part of the brain responsible for the mice's amorous behavior is as vestigial in humans as the appendix. The research, led by Harvard molecular neuroscientist Catherine Dulac and published online by Science this week (www.sciencexpress.org), suggests that the default social interaction for mice is to mate. Only a scent-based cue from another male inhibits a male's urge to mate and spurs him to fight. The number of genes that control this behavior is precisely one; it encodes the protein TRP2 that sits on the surface of certain olfactory nerves that detect pheromones. [...snip...snip...] If the mouse VNO controls basic behavior such as mating and fighting, and humans have remnants of this system, at what point in our evolutionary past did humans "overcome" being controlled by pheromones? USC's Liman, who studies the TRP gene family in primates, is trying to answer that question. But not everyone is pleased that humans have apparently largely abandoned pheromones when making mating decisions. "The perfume industry would like consumers to believe it's not vestigial," Liman says. According to many researchers, the fact that one gene has such a marked effect on sexual behavior was a surprise. Says neurobiologist Charles Zuker of the University of California, San Diego, "I would have expected that the sexual identity of a mate was not solely determined by one pheromone cue--mating is so extraordinarily important biologically." The bohemian mice seem to agree: Love is fundamentally more important--biologically speaking--than war. -------------
