PROVIDENCE, R.I. [Brown University] Cilia are one of nature's great multipurpose tools. The tiny, hair-like fibers protrude from cell membranes and perform all kinds of tasks in all kinds of creatures, from helping clear debris from human lungs to enabling single-celled organisms to swim. Now, physicists from Brown University have discovered something that could help scientists understand how cilia have been adapted for so many varied tasks.
The study, led by graduate student Ilyong Jung, looked at the cilia of the single-celled, water-dwelling paramecium. Paramecia are covered with cilia that beat like thousands of tiny oars, propelling the creatures through the water. At the same time, cilia around the paramecium's "oral groove" sweep nutrients inward, providing all-important nourishment. Through a series of experiments, the researchers showed that oral groove cilia appear to have different molecular motors than the rest of a paramecium's cilia.
This is the first time anyone has shown two motor behaviors by cilia in a single cell, says James Valles, chair of the Department of Physics at Brown and one of the paper's senior authors. With a bit more study, Valles hopes this finding could shed light on the molecular mechanisms responsible for these two motor behaviors.
"These motors are behaving differently in these two places in the same cell," Valles said. "We're hoping now that we can start pulling the two apart, maybe we can figure out what gives rise to these differences in behaviors. That could help us see why cilia can be so ubiquitous."
The findings are published in the Jan. 7, 2014, issue of the Biophysical Journal.
The researchers probed the behavior of the cilia by manipulating the viscosity of the liquid in which the paramecia swam. Using powerful microscopes and high-speed cameras, they observed how cilia behaved at a variety of viscosities, starting with the viscosity of plain water and increasing
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