Scientists were able to genetically modify mice to have increased sensitivity to a specific odor. The findings, recently published in the journal Cell Reports, may help future studies on the olfactory system. Odor receptors have been poorly studied in both mice and humans, making this type of research very important.
Researchers from Hunter College in New York modified the genome of a group of mice. They injected DNA strands into the nuclei of fertilized mouse egg cells and then let the eggs develop. The mice that got extra copies of this DNA strand were born with larger numbers of neurons that expressed a receptor for a specific odor. The odor chosen in the study was acetophenone, a sweet-smelling scent comparable to jasmine. The mice were otherwise normal, showing that the added gene was specific to acetophenone and no other odors. The team found that the mice with an amplified sense of smell for acetophenone could detect it at levels two orders of magnitude lower than unmodified mice. This was tested by training the mice to avoid the odor. The researchers also used fluorescent imaging to visualize the activation of the receptors, further proving that the added DNA had resulted in the development of more acetophenone receptors.
The olfactory system is not very well understood and scientists know little about how genes code for odor receptors. These findings provide a new strategy for studying these receptors and how they’re affected by different genes. The study shows that genes code for individual odors, independent of other olfactory receptors. The research team has created a company called MouSensor, intended to take further advantage of their new technology. The researchers hope to develop mice and other animals with the ability to detect the TNT in land mines. Rats have already been used for this task but modifying animals’ genomes can make them much more sensitive to the odor. The authors also intend to investigate the use of modified animals for disease detection in humans.
D’Hulst et al. MouSensor: A Versatile Genetic Platform to Create Super Sniffer Mice for Studying Human Odor coding. Cell Reports (2016).