Scientists have genetically modified mice in hopes of increasing their ability to smell TNT with 500 times the sensitivity of normal mice. If successful, the mice could provide a cheap and effective way to sniff out landmines and other explosive devices that haunt nations all over the world.
There are an estimated 45 to 100 million landmines buried around the world, according to the Red Cross, many of which are remnants of wars long since ended. The mines kill thousands each year and hamper development and economic growth. For many-war torn countries the cost of removing the mines is simply too much, and they’re left to suffer the occasional but inevitable consequences.
But a group of scientists at Hunter College in New York are trying to give them a lifesaving biosensor alternative. The group, led by Paul Feinstein, inserted a gene into odor sensing neurons in mice that could drastically increase their ability to smell TNT. Detecting an odor involves small molecules, called odorants, entering the nose and binding to receptors that sit on the ends of neurons there. Each neuron has a single type of receptor that binds to a specific odorant molecule, and when different odorant molecules bind to their receptors, they combine to generate the smells we’ve come to love, like coffee, and hate, like…decaf coffee.
There are about 1,000 different odorant receptors, so normally any given odorant that enters the nose would have a 1 in 1,000 chance of binding to its receptor and being detected. Using a gene that binds to an odorant in TNT, the scientists were able to increase the number of neurons able to detect the odorant. The average mouse already has about 4,000 neurons in its nose that can bind the telltale TNT odorant. With the gene, however, the scientists tipped the scale so that about half of the odor-detecting neurons contained the TNT receptor, increasing the chance that the odorant molecule is detected from 1 in 1,000 to 1 in 2.