Mice Rely on Individual Gene to Avoid Predators

       


          A recent study conducted by a Northwestern University research team lead by Thomas Bozza has discovered genes that are directly associated with how mice react to the smell of predators. While studying olfactory receptors, the research team found that there may be a single gene necessary for controlling a mouses sense of smell, which it relies on to avoid predators such as cats.

 Image:  © cynoclub / Fotolia


         The olfactory receptor they removed is the TAAR4 gene, which encodes a receptor that responds to chemicals in the urine of meat eaters. Mice who have this gene avoid the scent marks at all costs, but those who lack the TAAR4 receptor do not. This reveals that individual genes matter when it comes to sense of smell. Since mice have more than 1000 olfactory receptor genes, one would assume that removing a single olfactory receptor gene would not have a significant effect on the organisms ability to smell. Mice have 15 TAARs, one found in the brain and 14 in the nose, which are used to detect odors. These TAAR genes are very sensitive to amines. Mice lacking all 14 olfactory TAAR genes showed no response to the presence of amines. This led scientists to believe removing single genes may have an effect in the mouses sense of smell.
        Removal of the TAAR4 gene, which responds to phenylethylamine (PEA), a chemical found in carnivore urine, caused mice to have no response to the smell of predator cat urine. However, they still avoided other amines. These genes are highly conserved, and found in all the mammals the team had studied, including humans. Since they are highly conserved, it is likely that they are very important for survival. Neurons in the nose that express TAARs connect to a single region of the olfactory bulb, which receives the first olfactory information. This, may suggest that TAARs create hardwired responses to amines, and possibly even humans.


                                        REFERENCES:
Northwestern University (2013, April 29). Cat and mouse: One gene is necessary for mice to avoid predators.         ScienceDaily. Retrieved April 29, 2013, from http://www.sciencedaily.com­/releases/2013/04/130429154115.htm

Dewan, A., Pacifico, R.,  Zhan, R., Rinberg, D., Bozza, T (2013). Non-redundant coding of aversive odours in the main olfactory pathway. Nature, 2013; DOI: 10.1038/nature12114

Image:  © cynoclub / Fotolia