Scanning Transmission EM (STEM) of dynein ATPases

1987 ◽  
Vol 45 ◽  
pp. 798-799
Author(s):  
Kenneth A. Johnson ◽  
Silvio P. Marchese-Ragona ◽  
Joseph S. Wall
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
Transmission Electron Microscopy ◽  
Electron Scattering ◽  
Scanning Transmission Electron Microscopy ◽  
Mass Analysis ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Lines Of Evidence

The structure and molecular weight of the microtubule-dependent ATPase, dynein, was first established by scanning transmission electron microscopy (STEM) of dynein isolated from the cilia of Tetrahymena. It was shown that dynein consists of three globular heads joined to a common base by three slender, flexible strands. The globular heads have a diameter of 10-12 nm and the strands are 24 nm in length, such that the particles are 35 nm overall. Mass analysis by integration of electron scattering intensities in the STEM established a molecular weight of 1.9 million, with each head contributing 420,000. Several lines of evidence suggested that the base anchors the dynein to the A-tubule and the three independent, globular heads interact with the B-tubule of the adjacent outerdoublet in an ATP-dependent reaction to produce a force for sliding.

Nanomorphology of P3HT:PCBM-Based Absorber Layers of Organic Solar Cells after Different Processing Conditions Analyzed by Low-Energy Scanning Transmission Electron Microscopy

2012 ◽  
Vol 18 (6) ◽  
pp. 1380-1388 ◽  
Author(s):  
Marina Pfaff ◽  
Michael F.G. Klein ◽  
Erich Müller ◽  
Philipp Müller ◽  
Alexander Colsmann ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
Transmission Electron Microscopy ◽  
Solar Cells ◽  
Organic Solar Cells ◽  
Scanning Transmission Electron Microscopy ◽  
Low Energy ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission

AbstractIn this study the nanomorphology of P3HT:PC61BM absorber layers of organic solar cells was studied as a function of the processing parameters and for P3HT with different molecular weight. For this purpose we apply scanning transmission electron microscopy (STEM) at low electron energies in a scanning electron microscope. This method exhibits sensitive material contrast in the high-angle annular dark-field (HAADF) mode, which is well suited to distinguish materials with similar densities and mean atomic numbers. The images taken with low-energy HAADF STEM are compared with conventional transmission electron microscopy and atomic force microscopy images to illustrate the capabilities of the different techniques. For the interpretation of the low-energy HAADF STEM images, a semiempirical equation is used to calculate the image intensities. The experiments show that the nanomorphology of the P3HT:PC61BM blends depends strongly on the molecular weight of the P3HT. Low-molecular-weight P3HT forms rod-like domains during annealing. In contrast, only small globular features are visible in samples containing high-molecular-weight P3HT, which do not change significantly after annealing at 150°C up to 30 min.

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