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PHOTOMOVEMENT IN AN “EYELESS” MUTANT OF Chlamydomonas
Author(s) -
MorelLaurens N. M. L.,
Feinleib M. E.
Publication year - 1983
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1983.tb04457.x
Subject(s) - phototaxis , mutant , chlamydomonas , biology , stimulus (psychology) , microbiology and biotechnology , wild type , eyespot , chlamydomonas reinhardtii , biophysics , genetics , gene , psychology , psychotherapist
The function of the stigma (“eyespot”) in the green flagellate Chlamydomonas reinhardtii was investigated by comparing the photomovement of the wild‐type alga with that of an “eyeless” mutant ( ey 627). Movements of individual cells in response to a blue‐green stimulus light were recorded using a videomicroscope system and were analyzed using vectorial methods. Cells of the “eyeless” mutant were phototactic; at a high stimulus fluence rate, their swimming paths were directed away from the light source. Although the orientation of the mutant was not as strongly directional as that of the wild type, it was statistically significant. However, the swimming paths of the mutant cells were very erratic in the presence of the stimulus beam, undergoing frequent changes of direction. Despite the differences in their phototactic orientation, cells of mutant and wild type all showed a distinct step‐up photophobic response at the onset of stimulation. These results are consistent with the hypothesis that the stigma plays an accessory role in phototaxis, either by shading the photoreceptor or by acting as a quarter‐wave reflector.