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High Speed Cinemicrography of the Direct Photophobic Response of Euglena and the Mechanism of Negative Phototaxis *
Author(s) -
DIEHN BODO,
FONSECA JAMES R.,
JAHN THEODORE L.
Publication year - 1975
Publication title -
the journal of protozoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.067
H-Index - 77
eISSN - 1550-7408
pISSN - 0022-3921
DOI - 10.1111/j.1550-7408.1975.tb05216.x
Subject(s) - phototaxis , biophysics , euglena gracilis , transduction (biophysics) , euglena , microbiology and biotechnology , light intensity , chemistry , biology , optics , biochemistry , physics , botany , chloroplast , gene
SYNOPSIS. The shock reaction of Euglena gracilis strain Z to a sudden increase in light intensity (the “direct photophobic response”) was examined by high speed cinemicrography. The response is expressed as a turning reaction toward the dorsal side of the cell, after a transduction time of 0.1–0.5 sec after the onset of stimulation. Transduction times, turning rates, and flagellar beat frequencies were measured by analyzing the filmed sequences. The experimental data are consistent with a mechanism of directional homeostasis in negative phototaxis that is based upon shading of the photoreceptor by the cell's posterior end.