Quantitative analysis of the euglenoid (metaboly) movement

MARINO ARROYO; LUCA HELTAI; DANIEL MILLÁN; ANTONIO DESIMONE

Evanston, Illinois

Congreso; 48th Annual Technical Meeting of the Society of the Engineering Science (SES 2011); 2011

Society of Engineering Science

Most micro-organisms swim using cilia or flagella. Some euglenoids can also swim undergoing very large shape changes, in what is known as metaboly. The origin or function of this movement is not known. The ability of the members of the eugleoid family to perform metaboly has been correlated with the morphology of a structure supporting the cell membrane called pellicle. We perform a quantitative analysis of experimental videos capturing metaboly strokes. We first process the frames to obtain a smooth numerical parameterization of the stroke manifold in shape space, using nonlinear dimensionality reduction techniques. Mild mechanical assumptions allow us to reconstruct from these images the full velocity field on the surface of the cell, including the helical motions, up to rigid body motions. These are computed from a hydrodynamical analysis of swimming, under the assumption of low Re. This analysis establishes a clear relation between the pellicle structure and its function in mediating the euglenoid movement. We compare the net swimming speeds against observations, and investigate the optimality of the observed strokes.