Staining acetate

Lyim and co-workers carried out smdies of the Ap(io 35) peptide - derived from residues 10-35 of the p-amyloid responsible for Alzheimer s disease - which forms fibrils composed of parallel p-sheets [62]. The peptide was compared to its C-terminal PEG-derivatised analogue. TEM experiments showed that both formed fibrils [63] (Fig. 21) but the uranyl acetate stain was not found inside the peptide-PEG fibrils, indicating that PEG was at the outer edge of the fibril. 

Note Altematively, uranyl acetate staining may be carried out after immuno-labeling. 

Figure 16.7 TEM picture (uranyl acetate staining) of vesicles reported by Schenning etal. [44] (A) schematic representation of the bilayer, (B) palmitoyl-and (C) azobenzene-modified poly(propylene imine) dendrimers used in the construction of the aggregates...

Figure 8 Paclitaxel encapsulated into DQAsomes. (A) Transmission electron microscopic image (uranyl acetate staining). (B) Size distribution. (C) Cryo-electron microscopic image. Source-. From Ref. 43.

For sufficient contrast, most specimens will require lead staining after the uranium acetate stain. Although all conventional lead stains can be used, we found staining with Millonig s lead hydroxide for 2 min under N2 best for Lowicryl and LR Gold embedded material. 

When mother liquor from an enzyme recrystallization was stained with sodium silicotungstate at pH 7, most of the forms were indistinguishable from the 65-A structures of Fig. 2. However, there were also a few round objects 130-140 A in diameter, most of which appeared to have a central cavity (Fig. 3a). When the pH was lowered to 6, many more of the larger objects, both solid and with cavities, were observed (Fig. 3b), and at pH 5 nearly all of the forms were of this larger type (Fig. 3c). Uranyl acetate stained preparations at pH 4 also showed the 130-140-A objects almost exclusively, both with and without the ringlike appearance (Fig. 3d). These large forms may represent a specific molecular intermediate with which single enzyme particles and the crystals are in equilibrium. As the pH is lowered, the equilibrium between the 65-A and the 130-140-A structures is shifted in favor of the latter 13). 

Fig. 20 Micellar fibers of PMPSnPEOtn in mixtures of THF and water (25/75 by volume). TEM images (a) visualizing the poly silane core of miceUar fibers (unstained, bar represents 250 nm) (b) revealing the PEO shell using nranyl acetate staining, (c) showing an example of the bulges found for many of these fibers, (d) Schematic representation of the structure of the micellar fibers showing the PMPS core and the PEO shell. Reproduced with permission from [79], Sommerdijk et al. (2000) Macromolecules 33 8289. American Chemical Society...

For protein amounts over 1 pg/band, the Coomassie stain is recommended, then the silver stain. If you want to blot the protein afterward, you can stain the gel with Eosin, although it is better to stain the protein only on the blot. For larger amounts of protein, which need to treated with care (e.g., for a sequencing), acetate staining is the means of choice. 

Although many studies on DNA and DNA-protein interaction have utilized metal shadowing to produce bright-held image contrast, dark-held TEM (annular or spectroscopic) of unstained or uranyl acetate-stained and metal-shadowed nucleic acid-protein complexes also provides useful resolution. In Figure 5, a short length of DNA (2356 base pairs), with attached progesterone receptor, is revealed by dark-held TEM. The RecA protein has the ability to... 

Figure 1 illustrates the morphological features of a poly(ADP-ribose) polymerase preparation observed by dark field electron microscopy. It appears that most of the uranyl acetate stain, which preferentially binds DNA, is located at the periphery of the enzyme-DNA complex indicating that the sDNA is wrapped around the enzyme molecule (Fig. lA-C). 

Note It is occasionally recommended that sodium acetate be added to the reagent [2]. Thiophosphate insecticides with a simple P—S bond yield yellow chromatogram zones and those with a P=S double bond yield brown ones on a light brown background [10]. Further treatment of the stained chromatogram with iodine vapors increases the detection sensitivity [7] more than does spraying afterwards with caustic soda solution, which is also occasionally recommended [16, 17, 20, 21]. 

Fig.1. Electron micrograph of a mast cell in human heart tissue. The cytoplasm contains numerous secretory granules. The mast cell is adjacent to a coronary blood vessel, surrounded by collagen fibers and close to a myocyte. Uranyl acetate and lead citrate stained. Orig. magnif. lO.OOOx. 

Tape >System of Analysis. A tape system which is used widely for analysis in the Pediatric Laboratory is a system whose principle was developed by the author. A reagent is placed on a paper tape. The paper is covered with a membrane, such as cellophane, cellulose nitrate or cellulose acetate, porous to low molecular weight substances. Finally, the serum is placed above the porous membrane, so that diffusion of the components of serum take place and a stain is produced on the paper (60). This principle has been incorporated for example, with glucose oxidase, in the conmercially available Dextro-Sticks. In addition, a similar principle is being applied by some for the analysis of components in urine (Ames Co., South Bend, Indiana). 

FIGURE 5.3 Electron micrographs of whey protein isolate (WPI). Scanning electron microscopy of dry WPI powder (A). Transmission electron microscopy of WPI stained with uranyl acetate (B) nonextruded WPI Paste (40% moisture) and (C) extruded texturized WPI (100 °C, 40% moisture) (Onwulata et ai, 2003a). 

Figure 4. Electron micrographs of the polymerized vesicles of Lipid 1 (stained by 1% uranyl acetate).

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