Osmosensing neurons (ONs) swell to detect a decrease in salt concentration.
Bourque/Macmillan
Most cells have at least two mechanisms for maintaining homeostasis in response to changes in salt concentrations. Without these mechanisms, osmotic forces take over: more water and thus less salt outside cells leads water to flood into a cell. But this swelling doesn't occur in most cells because they pump ions out. Even if there is some swelling, the cells prevent membrane stretching by adding extra membrane to compensate.
The osmosensory neurons studied by Zhang and Bourque lack both of these responses, so they swell and contract with changes in salt concentration. “It's a behavior you expect from passive diffusion across a membrane,” says Bourque.
The...
