Euglenids exhibit an unconventional motility strategy amongst unicellular eukaryotes, consisting of large-amplitude highly con- certed deformations of the entire body (euglenoid movement or metaboly). A plastic cell envelope called pellicle mediates these deformations. Unlike ciliary or flagellar motility, the biophysics of this mode is not well understood, including its efficiency and molecular machinery. We quantitatively examine video recordings of four euglenids executing such motions with statistical learning methods. This analysis reveals strokes of high uniformity in shape and pace. We then interpret the observations in the light of a theory for the pellicle kinematics, providing a precise understand- ing of the link between local actuation by pellicle shear and shape control. We systematically understand common observations, such as the helical conformations of the pellicle, and identify previously unnoticed features of metaboly. While two of our euglenids exe- cute their stroke at constant body volume, the other two exhibit deviations of about 20% from their average volume, challenging current models of low Reynolds number locomotion. We find that the active pellicle shear deformations causing shape changes can reach 340%, and estimate the velocity of the molecular motors. Moreover, we find that metaboly accomplishes locomotion at hydrodynamic efficiencies comparable to those of ciliates and flagellates. Our results suggest new quantitative experiments, provide insight into the evolutionary history of euglenids, and sug- gest that the pellicle may serve as a model for engineered active surfaces with applications in microfluidics.

Reverse engineering the euglenoid movement

De Simone, Antonio
2012

Abstract

Euglenids exhibit an unconventional motility strategy amongst unicellular eukaryotes, consisting of large-amplitude highly con- certed deformations of the entire body (euglenoid movement or metaboly). A plastic cell envelope called pellicle mediates these deformations. Unlike ciliary or flagellar motility, the biophysics of this mode is not well understood, including its efficiency and molecular machinery. We quantitatively examine video recordings of four euglenids executing such motions with statistical learning methods. This analysis reveals strokes of high uniformity in shape and pace. We then interpret the observations in the light of a theory for the pellicle kinematics, providing a precise understand- ing of the link between local actuation by pellicle shear and shape control. We systematically understand common observations, such as the helical conformations of the pellicle, and identify previously unnoticed features of metaboly. While two of our euglenids exe- cute their stroke at constant body volume, the other two exhibit deviations of about 20% from their average volume, challenging current models of low Reynolds number locomotion. We find that the active pellicle shear deformations causing shape changes can reach 340%, and estimate the velocity of the molecular motors. Moreover, we find that metaboly accomplishes locomotion at hydrodynamic efficiencies comparable to those of ciliates and flagellates. Our results suggest new quantitative experiments, provide insight into the evolutionary history of euglenids, and sug- gest that the pellicle may serve as a model for engineered active surfaces with applications in microfluidics.
2012
Settore ICAR/08 - Scienza delle Costruzioni
microswimmers; self-propulsion; active soft matter
   Natural Interfaces for the elderly
   SAICT-POL/24048/2016
   Fundação para a Ciência e a Tecnologia, I.P.
   Concurso de Projetos de Investigação Científica e Desenvolvimento Tecnológico em Institutos e Escolas Politécnicas 2016
   SAICT-POL/24048/2016
File in questo prodotto:
File Dimensione Formato  
PNAS-2012-Arroyo-17874-9.pdf

accesso aperto

Tipologia: Published version
Licenza: Creative Commons
Dimensione 2.82 MB
Formato Adobe PDF
2.82 MB Adobe PDF

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11384/84058
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 93
  • ???jsp.display-item.citation.isi??? 89
social impact