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Reentrant Efficiency of Phototaxis in Chlamydomonas reinhardtii Cells

Choudhary, Sujeet Kumar and Baskaran, Aparna and Sharma, Prerna (2019) Reentrant Efficiency of Phototaxis in Chlamydomonas reinhardtii Cells. In: BIOPHYSICAL JOURNAL, 117 (8). pp. 1508-1513.

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Official URL: http://dx.doi.org/10.1016/j.bpj.2019.09.016


Phototaxis is one of the most fundamental stimulus-response behaviors in biology wherein motile microorganisms sense light gradients to swim toward the light source. Apart from single-cell survival and growth, it plays a major role at the global scale of aquatic ecosystems and bioreactors. We study phototaxis of single-celled algae Chlamydomonas reinhardtii as a function of cell number density and light stimulus using high spatiotemporal video microscopy. Surprisingly, the phototactic efficiency has a minimum at a well-defined number density, for a given light gradient, above which the phototaxis behavior of a collection of cells can even exceed the performance obtainable from single isolated cells. We show that the origin of enhancement of performance above the critical concentration lies in the slowing down of the cells, which enables them to sense light more effectively. We also show that this steady-state phenomenology is well captured by modeling the phototactic response as a density-dependent torque acting on an active Brownian particle.

Item Type: Journal Article
Publisher: CELL PRESS
Additional Information: Copyright of this article belongs to CELL PRESS
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Date Deposited: 27 Nov 2019 11:54
Last Modified: 27 Nov 2019 11:54
URI: http://eprints.iisc.ac.in/id/eprint/63824

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