The fluid-mosaic membrane theory in the context of photosynthetic membranes: Is the thylakoid membrane more like a mixed crystal or like a fluid?

2020 ◽  
Vol 252 ◽  
pp. 153246 ◽  
Author(s):  
Christian Wilhelm ◽  
Reimund Goss ◽  
Gyözö Garab
Keyword(s):  
Thylakoid Membrane ◽  
Mixed Crystal ◽  
Membrane Theory ◽  
Photosynthetic Membranes

Studies of Components of the Thylakoid Membrane of Undamaged and Damaged Spruce Trees at Different Mountain Sites

1993 ◽  
Vol 48 (11-12) ◽  
pp. 911-922 ◽  
Author(s):  
Aloysius Wild ◽  
Petra Strobel ◽  
Ute Flammersfeld
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Chlorophyll Content ◽  
Thylakoid Membrane ◽  
Electron Transport Rate ◽  
D1 Protein ◽  
Cytochrome F ◽  
West Germany ◽  
Transport Rate ◽  
Photosynthetic Membranes

During a five-year period, components of the thylakoid membrane in needles of the second generation of undamaged and damaged trees of Norway spruce were studied at three different mountain sites in West Germany. Visible signs of damage at these sites are a yellowing of the light-exposed sides of the needles as well as the loss of needles. The goal of this study was to determine damage-induced alterations in composition and physiological reactions of the thylakoid membranes in spruce needles. In order to meet this purpose, contents of chlorophyll a and b, electron transport rate of photosystem II, contents of the D 1 protein, cytochrome f, as well as P-700 were measured. The chlorophyll content in the needles of the damaged spruce trees was significantly lower than in the needles of the undamaged trees. In addition to this, the typical annual course of chlorophyll content was exclusively observed in the needles of the undamaged spruce trees. If related to dry weight, a drastic reduction of the electron transport rate and of the redox components of the thylakoid membrane was observed due to damage, indicating a degeneration of the photosynthetic membranes. The contents of D1 protein and the photosynthetic electron transport rates were also markedly reduced in the needles of the damaged trees, when related to chlorophyll content of thylakoids, suggesting an early and particular impairment of photosystem II. The comparison of spruce trees showing different signs of damage demonstrates that certain biochemical parameters concerning the photosynthetic membranes (chlorophyll, cytochrome f, ratio photosystem II/I) reflect the extent of damage and are suitable for an early indication of a beginning, but still invisible damage of spruce trees.

scholarly journals Supramolecular structure of the thylakoid membrane of Prochlorothrix hollandica: a chlorophyll b-containing prokaryote

1988 ◽  
Vol 91 (4) ◽  
pp. 577-586
Author(s):  
K.R. Miller ◽  
J.S. Jacob ◽  
T. Burger-Wiersma ◽  
H.C. Matthijs
Keyword(s):  
Thylakoid Membrane ◽  
Freeze Fracture ◽  
Thylakoid Membranes ◽  
Chlorophyll B ◽  
Photosynthetic Membranes ◽  
Green Plants ◽  
Membrane Surfaces ◽  
Chlorophylls A And B ◽  
Inner Surface ◽  
Etched Membrane

Prochlorothrix hollandica is a newly described photosynthetic prokaryote, which contains chlorophylls a and b. In this paper we report the results of freeze fracture and freeze etch studies of the organization of the photosynthetic thylakoid membranes of Prochlorothrix. These membranes exhibit four distinct fracture faces in freeze fractured preparations, two of which are derived from membrane splitting in stacked regions of the thylakoid membrane, and two of which are derived from nonstacked regions. The existence of these four faces confirms that the thylakoid membranes of Prochlorothrix, like those of green plants, display true membrane stacking and have different internal composition in stacked and non-stacked regions, a phenomenon that has been given the name lateral heterogeneity. The general details of these fracture faces are similar to those of green plants, although the intramembrane particles of Prochlorothrix are generally smaller than those of green plants by as much as 30%. Freeze etched membrane surfaces have also been studied, and the results of these studies confirm freeze fracture observations. The outer surface of the thylakoid membrane displays both small (less than 8.0 nm) and large (greater than 10.0 nm) particles. The inner surface of the thylakoid membrane is covered with tetrameric particles, which are concentrated into stacked membrane regions, a situation that is similar to the inner surfaces of the thylakoid membranes of green plants. These tetramers have never before been reported in a prokaryote. The photosynthetic membranes of Prochlorothrix therefore represent a prokaryotic system that is remarkably similar, in structural terms, to the photosynthetic membranes found in chloroplasts of green plants.

Freeze-Fracture Replication in the Ultrastructure of Blue-Green Algae

1967 ◽  
Vol 25 ◽  
pp. 74-75
Author(s):  
L. V. Leak
Keyword(s):  
Cell Wall ◽  
Electron Microscope ◽  
Green Algae ◽  
Three Dimensional ◽  
Freeze Fracture ◽  
Electron Microscopic ◽  
Photosynthetic Membranes ◽  
Blue Green Algae ◽  
Cell Biol ◽  
Cellular Components

Electron microscopic observations of freeze-fracture replicas of Anabaena cells obtained by the procedures described by Bullivant and Ames (J. Cell Biol., 1966) indicate that the frozen cells are fractured in many different planes. This fracturing or cleaving along various planes allows one to gain a three dimensional relation of the cellular components as a result of such a manipulation. When replicas that are obtained by the freeze-fracture method are observed in the electron microscope, cross fractures of the cell wall and membranes that comprise the photosynthetic lamellae are apparent as demonstrated in Figures 1 & 2.A large portion of the Anabaena cell is composed of undulating layers of cytoplasm that are bounded by unit membranes that comprise the photosynthetic membranes. The adjoining layers of cytoplasm are closely apposed to each other to form the photosynthetic lamellae. Occassionally the adjacent layers of cytoplasm are separated by an interspace that may vary in widths of up to several 100 mu to form intralamellar vesicles.

Structural analysis of the photosynthetic membrane from Ectothiorhodospira halochloris

1983 ◽  
Vol 41 ◽  
pp. 740-741
Author(s):  
H. Engelhardt ◽  
R. Guckenberger ◽  
W. Baumeister
Keyword(s):  
Lattice Structure ◽  
Bacterial Species ◽  
Hexagonal Lattice ◽  
Reaction Centre ◽  
Photosynthetic Membrane ◽  
Rhodopseudomonas Viridis ◽  
Photosynthetic Membranes ◽  
Ectothiorhodospira Halochloris ◽  
Main Components

Bacterial photosynthetic membranes contain, apart from lipids and electron transport components, reaction centre (RC) and light harvesting (LH) polypeptides as the main components. The RC-LH complexes in Rhodopseudomonas viridis membranes are known since quite seme time to form a hexagonal lattice structure in vivo; hence this membrane attracted the particular attention of electron microscopists. Contrary to previous claims in the literature we found, however, that 2-D periodically organized photosynthetic membranes are not a unique feature of Rhodopseudomonas viridis. At least five bacterial species, all bacteriophyll b - containing, possess membranes with the RC-LH complexes regularly arrayed. All these membranes appear to have a similar lattice structure and fine-morphology. The lattice spacings of the Ectothiorhodospira haloohloris, Ectothiorhodospira abdelmalekii and Rhodopseudomonas viridis membranes are close to 13 nm, those of Thiocapsa pfennigii and Rhodopseudomonas sulfoviridis are slightly smaller (∼12.5 nm).

Membrane theory

2017 ◽  
Author(s):  
David J. Steigmann
Keyword(s):  
Three Dimensional ◽  
Thin Sheets ◽  
Two Dimensional ◽  
Leading Order ◽  
Membrane Theory ◽  
Dimensional Theory ◽  
Small Thickness

This chapter develops two-dimensional membrane theory as a leading order small-thickness approximation to the three-dimensional theory for thin sheets. Applications to axisymmetric equilibria are developed in detail, and applied to describe the phenomenon of bulge propagation in cylinders.

Microwave synthesis of N-doped modified graphene/mixed crystal phases TiO2 composites for Na-ion batteries

2021 ◽  
Vol 615 ◽  
pp. 126276
Author(s):  
Shuaihao Wang ◽  
Yuanyi Zhu ◽  
Xuejiao Sun ◽  
Shengli An ◽  
Jinlong Cui ◽  
...  
Keyword(s):  
Microwave Synthesis ◽  
Mixed Crystal ◽  
Crystal Phases ◽  
Modified Graphene
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