It has been clarified that the swimming microorganism ciliate Tetrahymena runs up against the flow (shows running property) near the structure in the water due to the shape of the cells and the nature of the cilia.It was discovered by researchers at Kyoto University, University of Basel, Hokkaido University, Tohoku University, and Institute of Basic Biology.
This research started with the fact that the researchers were interested in the mechanism of their behavior when they saw that the cells that had flowed into the flow path mysteriously did not flow downstream in the student experiment.Ciliates that live in freshwater are thought to be swept downstream as they move along the stream, eventually flowing to the sea and dying, but they are not actually extinct.Therefore, it has long been thought that it has a running property, but the actual situation has not been clarified.
The researchers observed the swimming behavior of the unicellular ciliate Tetrahymena when artificial flow was applied.As a result, Tetrahymena near the wall showed clear running performance, in contrast to Tetrahymena far from the wall.In addition, the running property depends on the magnitude of the shear rate (spatial change of the flow velocity), and as the flow becomes stronger, not only the orientation of the cells of Tetrahimena is aligned to point upstream due to the hydrodynamic effect. , Tetrahimena that goes up against the flow has also come out.At this time, it was found that the cilia near the wall of Tetrahymena, which opposes the flow, are impeded in movement and the swimming ability is asymmetric.
Based on this element, when verified using a fluid simulation, the running property is not shown when the cell shape is spherical, but the spheroid such as Tetrahymena reproduces the running property even in the computer. I understood.Tetrahymena's "mechanical stimulus-response characteristics of cilia that generate propulsion" and "cell shape" suggest that Tetrahymena automatically opposes the flow in order to stay in an environment suitable for its own habitat. Was done.
This result is expected to contribute to the prediction of the habitat distribution of ciliates, which indirectly support our diet and the global environment, and the improvement of the prediction accuracy of environmental changes that accompany it.
Paper information:[Science Advances] Near-wall rheotaxis of the ciliate Tetrahymena induced by the kinesthetic sensing of cilia
