New study shows small prey able to detect predators by a chemical in their urine

Jun 21, 2011 by Bob Yirka report
Calero Creek Trail Bobcat. Image: Don DeBold

(PhysOrg.com) -- A team of biologists from Harvard Medical School have isolated a chemical found in the urine of many, if not all carnivores, that small rodents can smell and that causes them to respond accordingly; i.e. to move away or avoid areas where the chemical is present. In a paper published in the Proceedings of the National Academy of Science, the team found that the chemical, 2-phenylethylamine which is found in the urine of virtually all animals, is much more highly concentrated in predators, and rodents such as mice are able to detect and react to it.

The team, led by Assistant Professor of Cell Biology, Stephen Liberles, knew going in that rodents and other small prey are afraid of something in the urine of meat eaters, such as bobcats, but wanted to know what exactly in the urine was giving them away. To find out, the team started by studying olfactory receptors in , figuring it might be easier to see what the mice are finding and reacting to, rather than simply randomly looking for every single that appeared in predator urine. They started with TAAR4, a well known receptor family generally known to be responsible for strong reactions in rodents. They also knew that something in bobcat urine was able to set off these receptors in rodents, which is why bobcat urine is sold to farmers to keep rodents away.

Eventually, after much work, they were able to isolate the chemical in the bobcat urine that was setting off the receptors in the rodents; 2-phenylethylamine. In the bobcats, this chemical was found to be in very high concentrations, which made the researchers begin to wonder if it might be found in very high concentrations in all , which would mean, small would be able to smell it regardless of species.

To find out, the team undertook an exhaustive survey of many types of predators from as many sources as they could find, which mostly meant testing zoo animals. To give them something to compare with, they also tested as many herbivores as they could get their hands on. They also tested humans.

Their results showed that across the board, had much higher levels of 2-phenylethylamine in their urine than did any of the non-meat eating animals; though the researchers are not clear just yet on whether the high levels of the chemical in the urine is due to eating meat, or if it’s simply a trait of animals that happen to eat meat. Finding that out is their next goal.

Explore further: Male monkey filmed caring for dying mate (w/ Video)

More information: Detection and avoidance of a carnivore odor by prey, PNAS, Published online before print June 20, 2011, doi: 10.1073/pnas.1103317108

Abstract
Predator–prey relationships provide a classic paradigm for the study of innate animal behavior. Odors from carnivores elicit stereotyped fear and avoidance responses in rodents, although sensory mechanisms involved are largely unknown. Here, we identified a chemical produced by predators that activates a mouse olfactory receptor and produces an innate behavioral response. We purified this predator cue from bobcat urine and identified it to be a biogenic amine, 2-phenylethylamine. Quantitative HPLC analysis across 38 mammalian species indicates enriched 2-phenylethylamine production by numerous carnivores, with some producing >3,000-fold more than herbivores examined. Calcium imaging of neuronal responses in mouse olfactory tissue slices identified dispersed carnivore odor-selective sensory neurons that also responded to 2-phenylethylamine. Two prey species, rat and mouse, avoid a 2-phenylethylamine odor source, and loss-of-function studies involving enzymatic depletion of 2-phenylethylamine from a carnivore odor indicate it to be required for full avoidance behavior. Thus, rodent olfactory sensory neurons and chemosensory receptors have the capacity for recognizing interspecies odors. One such cue, carnivore-derived 2-phenylethylamine, is a key component of a predator odor blend that triggers hard-wired aversion circuits in the rodent brain. These data show how a single, volatile chemical detected in the environment can drive an elaborate danger-associated behavioral response in mammals.

Related Stories

Sniffing out lung cancer at early stages

Jan 27, 2010

New animal research from scientists at the Monell Center and collaborators demonstrates that body fluid odors can be used to identify animals with lung cancer tumors. The findings set the stage for studies to identify potential ...

Toward a urine test for detecting colon cancer

Apr 21, 2010

Scientists are reporting an advance toward development of a urine test for detecting colon cancer, the third most common cancer in the United States. Such a test could eventually compliment or even reduce ...

Recommended for you

Male monkey filmed caring for dying mate (w/ Video)

5 hours ago

(Phys.org) —The incident was captured by Dr Bruna Bezerra and colleagues in the Atlantic Forest in the Northeast of Brazil.  Dr Bezerra is a Research Associate at the University of Bristol and a Professor ...

Orchid named after UC Riverside researcher

22 hours ago

One day about eight years ago, Katia Silvera, a postdoctoral scholar at the University of California, Riverside, and her father were on a field trip in a mountainous area in central Panama when they stumbled ...

In sex-reversed cave insects, females have the penises

Apr 17, 2014

Researchers reporting in the Cell Press journal Current Biology on April 17 have discovered little-known cave insects with rather novel sex lives. The Brazilian insects, which represent four distinct but re ...

Fear of the cuckoo mafia

Apr 17, 2014

If a restaurant owner fails to pay the protection money demanded of him, he can expect his premises to be trashed. Warnings like these are seldom required, however, as fear of the consequences is enough to ...

User comments : 3

Adjust slider to filter visible comments by rank

Display comments: newest first

Jordian1
5 / 5 (1) Jun 21, 2011
Makes sense when you think about it. It's easy to get constrained thinking about natural selection in just physical features. Faster, stronger, tougher, more claws etc. But in reality survival is probably much more subtle. Chemical warfare, Darwin style.
Nik_2213
not rated yet Jun 21, 2011
Uh, this is why a domestic cat need catch very few mice for the rest to move out...
Of course, if your big, spotted tabby knocks down anything that hops, scurries or flies within range, that works, too...
Isaacsname
not rated yet Jun 21, 2011
I wonder how this works with humans.....

More news stories

Researchers successfully clone adult human stem cells

(Phys.org) —An international team of researchers, led by Robert Lanza, of Advanced Cell Technology, has announced that they have performed the first successful cloning of adult human skin cells into stem ...

Scientists tether lionfish to Cayman reefs

Research done by U.S. scientists in the Cayman Islands suggests that native predators can be trained to gobble up invasive lionfish that colonize regional reefs and voraciously prey on juvenile marine creatures.

Researchers develop new model of cellular movement

(Phys.org) —Cell movement plays an important role in a host of biological functions from embryonic development to repairing wounded tissue. It also enables cancer cells to break free from their sites of ...

Continents may be a key feature of Super-Earths

Huge Earth-like planets that have both continents and oceans may be better at harboring extraterrestrial life than those that are water-only worlds. A new study gives hope for the possibility that many super-Earth ...