Electron microscopy of membranes

Marty F. High voltage electron microscopy of membrane interactions in wheat. JHistochem Cytochem 1980 28 1129-1132. 

Karlsson, B., Hovmoller, S., Weiss, H., and Leonard, K., 1983, Structural studies of cytochrome reductase. Subunit topography determined by electron microscopy of membrane crystals of a subcomplex, J. Mol. Biol. 165 2878302. 

Fig. C2.7 Electron microscope picture of bacterial DNA partially released from the cell (bacteria E. coli) upon gentle breaking of the cell outer membrane (see Sections 2.4, 6.3 and 9.12). The figure illustrates how dense is the DNA packing under native conditions we see that even spilled out DNA is rather dense and tangled, we can therefore imagine how dense it was while still inside the cell. The scale bar in the image corresponds to 1 mm, or 1,000 nm — about the size of the cell. The figure is reproduced with permission from the classical paper Ruth Kavenoff and B.C. Bowen, "Electron Microscopy of Membrane-Free Folded Chromosomes from Escherichia Coli , Chromosoma, V. 59, n. 2, pp. 89— 101, 1976.

Knoll G and Plattner H 1989 Ultrastructural analysis of biological membrane fusion and a tentative correlation with biochemical and biophysical aspects Electron Microscopy of Subcellular Dynamics ed H Plattner (London CRC) pp 95-117... 

The three-dimensional structure of the bacterial membrane protein, bac-teriorhodopsin, was the first to be obtained from electron microscopy of two-dimensional crystals. This method is now being successfully applied to several other membrane-bound proteins. 

Unlike heliantholysin and congeners, the toxicity of metridiolysin is not prevented by sphingomyelin, but is inhibited by cholesterol in low concentration, as well as by certain related sterols (23). In addition, metridiolysin is activated by thiols such as dithiothreitol, and is reversibly inactivated by compounds having an affinity for SH-groups, such as p-hydroxy-mercuribenzoate. A third notable feature is that the action of metridiolysin on membranes involves, or is associated with, the formation of 33 nm rings demonstrable by electron microscopy of negatively stained preparations. 

Phospholipids, which are one of the main structural components of the membrane, are present primarily as bilayers, as shown by molecular spectroscopy, electron microscopy and membrane transport studies (see Section 6.4.4). Phospholipid mobility in the membrane is limited. Rotational and vibrational motion is very rapid (the amplitude of the vibration of the alkyl chains increases with increasing distance from the polar head). Lateral diffusion is also fast (in the direction parallel to the membrane surface). In contrast, transport of the phospholipid from one side of the membrane to the other (flip-flop) is very slow. These properties are typical for the liquid-crystal type of membranes, characterized chiefly by ordering along a single coordinate. When decreasing the temperature (passing the transition or Kraft point, characteristic for various phospholipids), the liquid-crystalline bilayer is converted into the crystalline (gel) structure, where movement in the plane is impossible. 

FIGURE 7.3 Structure of PSII membranes, macrocomplexes and LHCII antenna. Left from the top electron microscopy of grana stacks, PSII macrocomplexes, LHCII trimers, and LHCII oligomers. Right from the top Atomic structure of LHCII monomer (I and II are side and top views). Bottom part displays LHCII... 

A.F. Shoukry, H.M. Maraffie, and L.A. El-Shatti, X-Ray Photoelectron Spectroscopy and Electron Microscopy of Hydralazinium lon-selective Electrode Membranes s Surface, Eleclroanalysis, 18, 779-85 (2006). 

Electron Microscopy of Cellulose Acetate Reverse-Osmotic Membranes by Means of the Improved Replication Method... 

Samples for electron microscopy. The membranes are treated by freez-drylng of the same method as reported by Riley, Merten, Gardner (11). The samples immersed in Isopentane are cooled in liquid nitrogen and then dehydrated in vacuum. 

Electron microscopy of sectioned chloroplasts shows ATP synthase complexes as knoblike projections on the outside (stromal or N) surface of thylalcoid membranes these complexes correspond to the ATP synthase complexes seen to project on the inside (matrix or N) surface of the inner mitochondrial membrane. Thus the relationship between the orientation of the ATP synthase and the direction of proton pumping is the same in chloroplasts and mitochondria. In both cases, the Fl portion of ATP synthase is located on the more alkaline (N) side of the membrane through which protons flow down their concentration gradient the direction of proton flow relative to Fi is the same in both cases P to N (Fig. 19-58). 

Fig. 3. (a) Movement and (b) distribution (as shown by freeze-fracture electron microscopy) of integral membrane proteins. 

Toyoshima, C., Sasabe, H., Stokes, D.L. (1993). Three-dimensional cryo-electron microscopy of the calcium ion pump in the sarcoplasmic reticulum membrane. Nature (London) 362,469-471. 

Electron microscopy of radish radicle. Details of roots from seeds treated with 1/14-diluted reverse osmosis fraction, (a) Cortical cells showing protein-body-derived vacuoles (V) with remnants of electron-opaque protein material. Extremely swollen mitochondria (M) look like vacuoles with fine granular contents, (b) Detail of epidermal cell, showing swollen mitochondria (M), lipid droplets (L) and two dictyosomes (D). (c) The area enclosed in the rectangle in (b) is enlarged to show the two-membrane envelope and residual cristae (arrows) in a swollen mitochondrion. 

Electron microscopy of radish radicle. Details of columella cells from 16 h-control seed (a) and seed treated with 1/14-diluted reverse osmosis fraction (b-d). (a) Columella cells in the control are distinctly polarized and contain large amyloplasts (arrows). Nucleus (N). (b) Columella cells in treated roots are not polarized and contain no amyloplasts. The numerous electron-transparent vesicles are swollen mitochondria (M). (c) Detail showing swollen mitochondria (M) and starch-less plastids (P). (d) High magnification of swollen mitochondria showing the two-membrane envelope (arrows). 

Jakubovic et al (11) detected radioactivity in suckled rats after administration of 14c-A9-THC to the mothers. TLC showed A9-THC to be present in the infant brain. Electron microscopy of the infant brains showed a reduction in the number of ribosomes attached to the riuclear membrane of the brain cells. Hattoric et al (13) observed a similar effect after administration of A9-THC directly to infant rats. These results suggested significant transfer of A9-THC into the milk. 

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