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A FREEZE‐ETCHING STUDY OF THE RED ALGA PORPHYRIDIUM
Author(s) -
Neushul M.
Publication year - 1970
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1970.tb09929.x
Subject(s) - osmium tetroxide , thylakoid , biology , glutaraldehyde , membrane , stroma , chloroplast , biophysics , cytochemistry , red algae , botany , ultrastructure , photosynthesis , algae , biochemistry , electron microscope , chromatography , chemistry , optics , physics , immunohistochemistry , immunology , gene
Freeze‐etched cells of Porphyridium cruentum and P. aerugineum closely resemble those fixed with glutaraldehyde and post‐fixed with osmium tetroxide. Freeze‐etching reveals diversity in the non‐membranous and membranous parts of the cell. All the membranes are asymmetrical. The application of a double‐replica technique illustrates how the two sides of several cell membranes fit together. Interpretation of fracture patterns through the thylakoids and stroma leads to the suggestion that the thylakoids are composed of repeating structural units. A model of the photosynthetic apparatus is proposed. It is suggested that the thylakoids of Porphyridium and other red algae are not always “free” but can be stacked much like those of other plants.