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Cell‐wall structure and supramolecular organization of the plasma membrane of marine red algae visualized by freeze‐fracture
Author(s) -
TSEKOS I.,
REISS H.D.,
SCHNEPF E.
Publication year - 1993
Publication title -
acta botanica neerlandica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.871
H-Index - 87
eISSN - 1438-8677
pISSN - 0044-5983
DOI - 10.1111/j.1438-8677.1993.tb00689.x
Subject(s) - microfibril , membrane , cell wall , biophysics , vesicle , golgi apparatus , fibril , chemistry , supramolecular chemistry , crystallography , biology , biochemistry , endoplasmic reticulum , cellulose , crystal structure
SUMMARY The cell‐wall structure and the supramolecular organization of the plasma membrane in 29 species of red algae were studied both in replicas of rapidly frozen cells and in ultrathin sections. Most of the marine red algae investigated have a random distribution of the microfibrils of the cell walls; in a few cases there is a tendency to parallel alignment. Laurencia obtusa is an exception in which apart from a random distribution, microfibrils are arranged parallelly in a certain wall layer. The microfibrils have a cylindric or ribbon‐like morphology. In a number of species, microfibrils consist of two, three or four linear subcomponents (sub‐fibrils). In certain species two or three microfibrils can be bundled. In Erythrocladia subintegra, Radicilingua reptans and Laurencia obtusa the plasma membrane exhibits randomly distributed linear microfibril‐terminal complexes. All results favour the suggestion that the linear terminal complexes in the plasma membrane of the cells of the above mentioned species are involved in the biosynthesis, assembly and orientation of microfibrils. In the plasma membrane a number of other intramembranous particles are aggregated in various complexes (tetrads, complexes of six subunits, crystalline complexes, particle strings). Intramembranous particle complexes composed of four subunits ‘membrane tetrads’ have been observed in the plasma membrane and in the membranes of mucilage sacs of all red algae investigated. The ‘membrane tetrads’ are thought to be membrane‐bound multi‐enzyme complexes participating in the synthesis of the matrix polysaccharides. Observations of ultrathin sections suggest that the Golgi system and the inflated Golgi‐derived vesicles with fibrillar contents contribute to the formation of the wall. Our results support the view that the biosynthesis of cell‐wall skeletal and matrix polysaccharides in red algae are spatially separated.