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Mitochondrial DNA
Mitochondrial DNA imaged by Tapping-Mode Atomic Force Microscopy in liquid.
Mitochondria are subcellular organelles and they possess a genome which is partially independent from a replicative point of view from nuclear chromosomes.We studied the correspondences between each visible band of agarose gel electrophoresis and the different topological forms of mitochondrial DNA by means of Atomic Force Microscopy.Also the damage induced by tert-butylhydroperoxide (TBH) on mtDNA was invetigated in hepatocytes and in mitochondria isolated from rat liver. Click on the images to see a larger view
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Mitochondrial
DNA
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Section analysis of a mtDNA molecule. The measured height is very close to the known DNA diameter, whereas, the measured width is much larger than the true value. This is due to the "convolution" of DNA molecule with the shape of the tip, reduced but not eliminated by the use of the supertip.
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Relationship between different bands and conformations as imaged by TMAFM in liquid. a) The slowest band is characterized by the presence of complex structures constituted by more than one molecule with partly condensed DNA. b) The second band represents linear mtDNA, with fragments and whole length molecules. c) The fastest band corresponds to the supercoiled conformation with molecules characterised by opposing segments very near to each other.
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