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Updated: Aug 1, 2026
13:06
Visualization of miniSOG Tagged DNA Repair Proteins in Combination with Electron Spectroscopic Imaging (ESI)
Published on: September 24, 2015
Electron microscope visualization of chromatin and other DNA-protein complexes
Annual Review of Biophysics and Bioengineering
|January 1, 1978
Summary
This review covers direct mounting techniques for electron microscopy (EM). Proper fixation is crucial for accurate visualization and purification of labile samples.
Area of Science:
- Microscopy
- Electron Microscopy Techniques
Background:
- Direct mounting is essential for visualizing complex structures.
- Proper sample preparation is key in electron microscopy.
Purpose of the Study:
- To review current direct mounting techniques in electron microscopy.
- To illustrate the application of different mounting methods using micrographs.
- To emphasize the importance of controlled fixation for sample analysis.
Main Methods:
- Review of existing direct mounting techniques.
- Illustration of methods with micrographs.
- Discussion of fixation control.
Main Results:
- Various direct mounting techniques are currently employed.
- Micrographs demonstrate the utility of different methods.
- Controlled fixation enhances correlation and enables purification.
Conclusions:
- Novices should master one technique on simple samples before complex ones.
- Confidence in fixation allows correlation of EM observations with solution structures.
- Effective fixation is vital for purifying labile biological samples.
Related Concept Videos
02:21Chromatin Packaging
Each human somatic cell contains 6 billion base-pairs of DNA. Each base-pair is 0.34 nm long, which means that each diploid cell contains a staggering 2 meters of DNA. How is such a long DNA strand packed inside a nucleus measuring only 10 - 20 microns in diameter?
The chromatin
In combination with specialized DNA binding protein called Histones, the DNA double helix forms a compact DNA: protein complex called chromatin. The chromatin itself is further compacted into higher-order structures.
The chromatin
In combination with specialized DNA binding protein called Histones, the DNA double helix forms a compact DNA: protein complex called chromatin. The chromatin itself is further compacted into higher-order structures.
01:01Euchromatin
The extent of chromatin compaction can be studied by staining chromatin using specific DNA binding dyes. Under the microscope, the dense-compacted regions take up more dye, appearing darker, while the less-compact areas take up less dye and appear lighter. Based on the compaction level, chromatins are classified into two primary forms – euchromatin and heterochromatin.
Euchromatin is the less dense region of the chromatin and stains lighter. Euchromatin contains histone H3 extensively...
Euchromatin is the less dense region of the chromatin and stains lighter. Euchromatin contains histone H3 extensively...
01:17Studying the Cytoskeleton
The cytoskeletal architecture can be studied using different microscopic and biochemical techniques. Electron microscopy was instrumental in discovering the cytoskeletal architecture around the 1960s, which allowed obtaining structural information at a high-resolution level. However, the sample preparation procedure often limits this ability in biological samples. Several protocols have been developed over the years to optimize sample preparation. In one of the protocols known as rotary...
01:25Overview of Electron Microscopy
The wavelengths of visible light ultimately limit the maximum theoretical resolution of images created by light microscopes. Most light microscopes can only magnify 1000X, and a few can magnify up to 1500X. Electrons, like electromagnetic radiation, can behave like waves, but with wavelengths of 0.005 nm, they produce significantly greater resolution up to 0.05 nm as compared to 500 nm for visible light. An electron microscope (EM) can create a sharp image that is magnified up to 2,000,000X.
01:28Cryo-electron Microscopy
Conventional electron microscopy (EM) involves dehydration, fixation, and staining of biological samples, which distorts the native state of biological molecules and results in several artifacts. Also, the high-energy electron beam damages the sample and makes it difficult to obtain high-resolution images. These issues can be addressed using cryo-EM, which uses frozen samples and gentler electron beams. The technique was developed by Jacques Dubochet, Joachim Frank, and Richard Henderson, for...
01:32Chromatin Packaging
Each human somatic cell contains 6 billion base pairs of DNA. Each base pair is 0.34 nm long, meaning each diploid cell contains a staggering 2 meters of DNA. This long DNA strand is packed inside a nucleus measuring only 10-20 microns in diameter with the help of specialized DNA-binding proteins called histones. Together they form a compact DNA-protein complex called chromatin. The chromatin is further compacted into higher-order structures. The highest level of compaction is achieved during...