Structure and Function in the Euglenoid Eyespot Apparatus: The Fine Structure, and Response to Environmental Changes

The microanatomy of the eyespot apparatus of Euglena gracilis Z was examined with the electron microscope. The stigma was found to be a membrane-bounded organelle showing no close homology with the chloroplast or any other organelle. The structure and pigment content of the stigma both diminish with...

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Bibliographic Details
Published in:Planta 1972-01, Vol.105 (1), p.1-14
Main Authors: Kivic, Peter A., Vesk, Maret
Format: Article
Language:English
Subjects:
Chloroplasts
Cytoplasm
Electron microscopes
Euglena
Flagella
Globules
Organelles
Pigments
Plant cells
Ribosomes
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Summary:The microanatomy of the eyespot apparatus of Euglena gracilis Z was examined with the electron microscope. The stigma was found to be a membrane-bounded organelle showing no close homology with the chloroplast or any other organelle. The structure and pigment content of the stigma both diminish with extended heterotrophic growth, and quickly regain normal dimensions upon exposure to light. Synthesis of the red pigment is particularly sensitive to inhibition by chloramphenicol, whereas construction of the structure itself is specifically inhibited by cycloheximide. The paraflagellar body appears to consist of two sets of parallel 80 Å striations intersecting at 60°. It is within the flagellar membrane, but separated from the axoneme by another structure, the paraflagellar rod. This elongated structure has an ordered substructure which appears as intersecting sets of parallel striations; part of its basal portion projects as a circular flange which makes contact with the paraflagellar body.
ISSN:0032-0935
1432-2048
DOI:10.1007/bf00385158