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X-ray diffraction image of the double helix structure of the DNA molecule, taken 1952 by Raymond Gosling, commonly referred to as "Photo 51", during his work with Rosalind Franklin on the structure of DNA Source King's College London Archives: KDBP1/1/867.
Apoptotic DNA fragmentation is a natural fragmentation that cells perform in apoptosis (programmed cell death). DNA fragmentation is a biochemical hallmark of apoptosis.In dying cells, DNA is cleaved by an endonuclease that fragments the chromatin into nucleosomal units, which are multiples of about 180-bp oligomers and appear as a DNA ladder when run on an agarose gel. [8]
The apoptotic DNA fragmentation is being used as a marker of apoptosis and for identification of apoptotic cells either via the DNA laddering assay, [2] the TUNEL assay, [3] [4] or the by detection of cells with fractional DNA content ("sub G 1 cells") on DNA content frequency histograms e.g. as in the Nicoletti assay.
DNA laddering (left) visualised in an agarose gel by ethidium bromide staining. A 1 kb marker (middle) and control DNA (right) are included.. DNA laddering is a feature that can be observed when DNA fragments, resulting from Apoptosis DNA fragmentation are visualized after separation by gel electrophoresis the first described in 1980 by Andrew Wyllie at the University Edinburgh medical school ...
Sperm Chromatin Structure Assay (SCSA) is a diagnostic approach that detects sperm abnormality with a large extent of DNA fragmentation. [1] First described by Evenson in 1980, the assay is a flow cytometric test that detects the vulnerability of sperm DNA to acid-induced denaturation DNA in situ. [2]
Sperm cell DNA fragmentation In an average male, less than 4% of his sperm cells will contain fragmented DNA. However, partaking in behaviors such as smoking can significantly increase DNA fragmentation in sperm cells. There is a negative correlation between the percentage of DNA fragmentation and the motility, morphology, and concentration of ...
During apoptosis, a cell goes through a series of steps as it eventually breaks down into apoptotic bodies, which undergo phagocytosis.In the context of karyorrhexis, these steps are, in chronological order, pyknosis (the irreversible condensation of chromatin), karyorrhexis (fragmentation of the nucleus and condensed DNA) and karyolysis (dissolution of the chromatin due to endonucleases).
The DNA band can also be cut out of the gel, and can then be dissolved to retrieve the purified DNA. The gel can then be photographed usually with a digital or polaroid camera. Although the stained nucleic acid fluoresces reddish-orange, images are usually shown in black and white (see figures).