Summary
Eyespot membranes in zoospores of the green algaChlorosarcinopsis gelatinosa were studied with the freeze-fracture technique. The PF of the plasmalemma overlying the eyespot lipid globules contains significantly greater numbers of intramembraneous particles (IMP; 8,200 IMP/μm2) compared to other areas of the plasmalemma (2,100 IMP/μm2). In the eyespot area the EF of the plasmalemma reveals no IMP, but regularly arranged depressions corresponding to the PF particles. Sizes of PF particles are not significantly different between the eyespot area and other areas of the plasmalemma. Zoospore settlement starts approximately two hours after release and involves in sequence, rounding up of the cells, retraction of the flagella and secretion of a cell wall. Eyespot membrane specializations on the PF of the plasmalemma disappear during flagellar retraction and before cell wall secretion.
The functional significance of eyespot membrane specializations is discussed in accordance with the view that these membranes are engaged in photoreception and primary sensory transduction relating to green algal phototaxis.
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Melkonian, M., Robenek, H. Eyespot membranes in newly released zoospores of the green algaChlorosarcinopsis gelatinosa (Chlorosarcinales) and their fate during zoospore settlement. Protoplasma 104, 129–140 (1980). https://doi.org/10.1007/BF01279375
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DOI: https://doi.org/10.1007/BF01279375