High-speed video observation of swimming behavior and flagellar motility ofProrocentrum minimum (Dinophyceae)

Abstract

Summary.To understand the functions of the longitudinal and transverse flagella of dinoflagellates, the flagellar waveform and frequency of each flagellum were observed by high-speed video-recording. The longitudinal flagellum emerged from the anterior end of the cell and beat with a planar undulating wave whose plane was perpendicular to the valval sutural plane. The transverse flagellum curved around the anterior end of the cell and beat with a helical wave, with different alternating half pitches. The half pitch corresponding to the parts farther from the cellular antero-posterior axis was shorter than that of the parts closer to the axis. This pattern is described by the ratio of the outer-parts half pitch to the pitch of the whole period of the helix and seems to be characteristic of the dinoflagellates' transverse flagellum.

Functional roles of the transverse and longitudinal flagella in the swimming motility ofProrocentrum minimum(Dinophyceae)

“…Formulae for the flagella The flagellar waves of the transverse and longitudinal flagella (Fig.·1A,B) are reconstructed as modified helical and sinusoidal waves, respectively (Figs·2C, 3), using variables from Miyasaka et al (1998). Flagellar motion is formulated in the cell frame.…”

“…It has two different pitches depending on the distance from the cellular antero-posterior axis ( Fig.·1C-E; Miyasaka et al, 1998). The waveform is formulated here as a helical wave whose axis is a baseline circle of [xbt, rtcos(st/rt), rtsin(st/rt)] T (0ഛstഛ2πrt), where xbt and rt are the x coordinates and the radius of the circle, respectively.…”

“…where r represents rt(st,t) or r1(s1,t), with values taken from Miyasaka et al (1998). The fluid velocity around the cell body is described by the Stokes' flow because of its small Reynolds number (Jones et al, 1994).…”

“…In a previous study (Miyasaka et al, 1998), the motility of Prorocentrum minimum (Fig.·1A) was investigated. Briefly, P. minimum was found to swim along a helical trajectory with the same side of the cell always facing the axis of the trajectory as, for example, lunar motion with respect to the Earth (Fig.·1B).…”

Controllable alignment of elongated microorganisms in 3D microspace using electrofluidic devices manufactured by hybrid femtosecond laser microfabrication

“…One conventional method of performing such observations is to use an optical microscope combined with a high-speed camera [6][7][8][9] . For a detailed and in-depth analysis of the motions, observation from various angles is useful.…”