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Effects of viscosity on phototactic movement and period of cell rotation in Cryptomonas sp.
Author(s) -
UematsuKaneda Hisako,
Furuya Masaki
Publication year - 1982
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1982.tb00324.x
Subject(s) - phototaxis , rotation period , period (music) , rotational speed , rotation (mathematics) , cellulose , viscosity , chemistry , biophysics , biology , botany , physics , materials science , biochemistry , astrophysics , geometry , composite material , stars , mathematics , quantum mechanics , acoustics
The swimming speed, the period of cell rotation, and the critical dark period between intermittent light pulses in the positive phototactic response of Cryptomonas sp. strain IAM CR–1 were measured in the presence of methyl cellulose, which slows down the cell movement by raising the viscosity of the medium. The cell rotated once while it swam one pitch of the helical path, irrespective of the rotational period. The period of helical movement (the rotational period) was 0.65 s and 0.45 s in the presence and absence of 4.5 g/liter methyl cellulose, respectively. The phototactic response to repeated pulses of light could no longer be induced when the dark interval exceeded 0.33 s in medium with 4.5 g/liter methyl cellulose and 0.23 s in medium without it. The ratio of the critical dark period between repeated light pulses to the rotational period was always about 0.5, although the rotational period was lengthened 1.4 times with methyl cellulose. Thus, the present results clearly demonstrated that it is this ratio which is crucial for phototaxis, rather than the absolute length of the critical dark period.