Flagellar motions in phototactic steering in a brown algal swarmer.
Using infrared high-speed video microscopy, we observed light-triggered transitory flagellar motions in flagellate reproductive cells (swarmers) of a brown alga, Scytosiphon lomentaria, under primary helical swimming conditions before and during negative phototactic orientation to unilateral actinic light. The posterior flagellum, which is autofluorescent and thought to be light-sensing, was passively dragged in the dark and exhibited one to several rapid lateral beats during orientation changes for phototactic steering. Notably, a brief cessation of anterior flagellar beating was occasionally observed concomitantly with rapid beats of the posterior flagellum. This behavior caused a pause in helical body rotation, which may contribute to the accuracy of phototactic steering. Thus, coordinated regulation of the movement of the two flagella plays a crucial role in phototactic steering.
Matsunaga
Shigeru
S
Hayama Center for Advanced Studies, Graduate University for Advanced Studies (SOKENDAI), Hayama, Kanagawa, Japan. matsunaga_shigeru@soken.ac.jp
Uchida
Hiroko
H
Iseki
Mineo
M
Watanabe
Masakatsu
M
Murakami
Akio
A
D005407:Flagella / Q000502:physiology*; D008027:Light; D009068:Movement; D000459:Phaeophyceae / Q000502:physiology*; D012399:Rotation