Tasting light
Human taste receptors are specialized to distinguish several distinct compounds: sugars taste sweet, salts taste salty, and acidic compounds taste sour. Now a new study from MIT finds that the worm Caenorhabditis elegans has taken its powers of detection a step further: The worm can taste hydrogen peroxide, triggering it to stop eating the potentially dangerous substance. Being able to taste hydrogen peroxide allows the worm to detect light, which generates hydrogen peroxide and other harmful reactive oxygen compounds both within the worm and in its environment. “This is potentially a brand-new mechanism of sensing light,” says Nikhil Bhatla, the lead author of the paper and a postdoc in MIT’s Department of Biology. “All of the mechanisms of light detection we know about involve a chromophore — a small molecule that absorbs a photon and changes shape or transfers electrons. This seems to be the first example of behavioral light-sensing that requires...