Natures wonders: learning how Euglena move (Introduction)

by David Turell , Friday, March 08, 2019, 21:10 (2085 days ago) @ David Turell

Just the beginning of research into this single-celled animal:

https://phys.org/news/2019-03-motility-euglena.html

"The large-amplitude and coordinated body deformations observed in Euglena are typically referred to as 'euglenoid movement,' or 'metaboly.' Metaboly varies greatly between species and sometimes even within a species, ranging from a rounding and gentle bend or twist to periodic and highly concerted peristaltic waves that travel along the cell body.

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"Dilute cultures of Euglena cells generally swim using their flagellum and without changing their body shape. Arroyo and his colleagues, however, observed that as time passed and the fluid under the microscope evaporated, their culture became more crowded and cells started to develop metaboly.

"'Inspired by these observations and amateur YouTube videos, we hypothesized that the cell deformations could be triggered by contact with other cells or boundaries in a crowded environment, and that under these conditions, metaboly could be useful to crawl, rather than swim," Antonio De Simone, another researchers involved in the study, told Phys.org.

"Confirming this hypothesis was remarkably easy. As soon as we slightly pressed cells between two glass surfaces, or drove them into thin capillaries, they started to systematically perform metaboly, which resulted in the fastest crawling by any cell type, as far as we know," added Giovanni Noselli, the first author of the study.

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"'We found that, thanks to their peristaltic deformations, Euglena can push either on the walls or on the fluid to move forward, making of metaboly a remarkably robust mode of confined locomotion," De Simone said. "They can actually move displacing very little fluid in a 'stealthy' propulsion mode, and they cannot be stopped even if the hydraulic resistance in the capillary is increased substantially."

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"'If crawling by metaboly is so advantageous, one may wonder why it is not conserved amongst other species," Arroyo said. "The answer is that it requires an intricate machinery, the pellicle, which is a striated envelope made out of elastic strips connected by molecular motors. This selectively deformable surface lies somewhere the rigid wall of plant cells and the fluid envelope of animal cells. Beyond biology, we think that the underlying physical/geometric principles that enable shape changes of this envelope can be applied to artificial engineered systems, e.g. in soft robotics.'"

Comment: It may be found that Euglena move like bacteria do since so much of evolution is mimicry as in the so-called convergence.