RRC ID 21591
Author Matsunaga S, Watanabe S, Sakaushi S, Miyamura S, Hori T.
Title Screening effect diverts the swimming directions from diaphototactic to positive phototactic in a disk-shaped green flagellate Mesostigma viride.
Journal Photochem Photobiol
Abstract We found diaphototactic behavior (i.e. the cells swim perpendicularly with respect to the incident light) in a strain with colorless eyespot of a unicellular disk-shaped green flagellate Mesostigma viride. Lacking pigments completely in the eyespot, the screening effect in this strain was due only to the central part of the chloroplast whose cross section was thin. The diaphototaxis was most obvious when unilateral green stimulus light (520-580 nm) was given, whereas positive phototaxis appeared when given blue light (430-490 nm). The choice between diaphototaxis and (ordinary) phototaxis depended entirely on the transmission (%T) of the cell body against each wavelength of the stimulus: the green light penetrated well (%T > 90%), whereas the blue light was considerably shaded by the chloroplast (50% < %T < 70%). The fraction of positive phototactically behaving cells against each wavelength was in proportion to the front-to-back contrast value obtained at each individual wavelength. The fraction of diaphototaxis was inversely proportional to it. In addition, bilateral stimulus irradiations to wild-type cell with colored eyespot provided useful information about the principle of the diaphototactic steering.
Volume 77(3)
Pages 324-32
Published 2003-3-1
DOI 10.1562/0031-8655(2003)077<0324:sedtsd>2.0.co;2
PMID 12685662
MeSH Animals Chlorophyta / cytology Chlorophyta / physiology* Chlorophyta / radiation effects Models, Biological Movement Photobiology
IF 2.721
Times Cited 9
Algae NIES-477 NIES-476