Pheromone Gene Found

ByJoseph B. Verrengia

Aug. 28, 2000 -- Scientists have identified the first human gene that may be linked to pheromones, odorless molecules that in other animals trigger primal urges, including sex, defense and kinship.

Experts describe the discovery as possibly opening a new doorinto the role of pheromones in human development.

In animals, researchers have documented how pheromones tracecomplex neurological paths to stimulate parts of the brain that aredeeply rooted in instinct.

Researchers have long believed that humans also communicatethrough pheromones, but until now they had been unable to find anyof the equipment needed to detect these potent molecules.

Nose Holds Detector

Now, in experiments at Rockefeller University and Yale,neurogeneticists have isolated a human gene, labeled V1RL1, thatthey believe encodes for a pheromone receptor in the mucous liningof the nose. A receptor is a patch on the surface of a cell thatbinds with specific molecules, like a lock that accepts only aspecific key.

“This is the first convincing identification of a humanpheromone receptor,” said University of Colorado biochemist JosephFalke.

Humans share the V1RL1 gene with rodents and other mammals thatrely heavily on pheromone cues to survive.

However, it has not been determined whether the gene is activein humans or which pheromone-induced behavior the gene mightinduce.

“The ultimate test will be to find a pheromone that binds tothe receptor and triggers a measurable physiological response,”Falke said.

The research was published in the September issue of the journalNature Genetics.

Researchers took samples from a gene bank and scanned them formatches to the rodent genes from the V1r family. They found eightmatches in human genetic material.

Further testing showed that seven of the eight human V1r genesare inoperative. The potentially functional gene, called V1RL1,subsequently was found in 11 out of 11 randomly chosen people fromvarying ethnic backgrounds, researchers said.

Reactionary Signal

While rodents and other creatures essentially are reactiveanimals that depend heavily on pheromones for behavioral cues,humans use their larger brains to rely more on judgment and complexsensory cues, such as vision.

“In mice, we think there are more than 100 functioning genes inthe V1r family,” said Ivan Rodriguez of Rockefeller University,lead author of the study. “But in humans, V1RL1 may very well bethe sole functioning gene in the family.”

“Why has it hung around all this time?” said Charles Wysockiof the Monell Chemical Senses Center in Philadelphia. “It must bevery important if it has outlived all of its predecessors.”

Scientists aren’t sure what happened to the other 99 genes.

“It’s unheard of that a family of 100 genes in mice is reducedto a single gene in humans,” said the study’s senior author, PeterMombaerts.

In most mammals, pheromones usually are detected by aspecialized organ inside the nose or mouth called the vomeronasalorgan, or VNO. Nerves connect it to parts of the brain involved inreactions rather than cognition.

In humans, the organ appears in embryos with its nerve cellsextending into the developing brain. For several weeks, it servesas a pathway for hormones vital to sexual development and maturity.However, the VNO in humans shrinks and stops working before birth.

To What Effect?

Researchers have long suspected that humans communicate withpheromones. But how pheromones are produced and how they aredetected across a room, or even greater distances, is poorlyunderstood.

One 1998 study at the University of Chicago demonstrated thatpheromones in underarm sweat prompt women living in close quartersto synchronize their menstrual cycles.

Some companies put pheromones in perfumes. Chemical makers baitinsect traps with pheromones.

Mombaerts said it is too early to tell whether the genediscovery might lead to pheromone-based medicines.

However, the potential for pheromone misuse worries someresearchers and bioethicists.

“Safeguards will be needed to prevent the manipulation of humanbehavior,” Falke said. “We won’t want pheromones showing up inmagazine ads, or pumped through ventilation systems at the mall.”

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