To make their mice hypersensitive to explosives, the researchers altered the gene responsible for the DNT receptor so that the transgenic mice have as many as one million neurons in which the odor receptor is tuned to the fragrance of a land mine.

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To breed a better mine-sweeper, the Hunter researchers took advantage of the recent discovery of a receptor in the rodent brain for the odor of a chemical known as 2, 4-dinitrotoluene (DNT), which is essentially the same as TNT, which stands for trinitrotoluene.

WSJ: Sniffing Out a More-Efficient Mine Sweeper

Each odor-sensing neuron has just one type of aroma receptor.

WSJ: Sniffing Out a More-Efficient Mine Sweeper