Single strand break 520 Subject

Subjecting cells to oxidative stress can result in severe metabolic dysfunctions, including peroxidation of membrane lipids, depletion of nicotinamide nucleotides, rises in intracellular free Ca ions, cytoskeletal disruption and DNA damage. The latter is often measured as formation of single-strand breaks, double-strand breaks or chromosomal aberrations. Indeed, DNA damage has been almost invariably observed in a wide range of mammalian cell types exposed to oxidative stress in a number... 

Figure 4.1 The comet assay. A single-cell suspension is embedded in agarose on a slide. Cells are then subject to lysis followed by electrophoresis. If present, damaged DNA migrates out of the nucleoid structure during electrophoresis to producing a characteristic comet shape. Double-strand breaks are revealed under neutral conditions, whereas alkali conditions additionally show single-strand breaks and alkali labile sites. Image analysis of stained DNA is used to quantitate the amount of damaged DNA in the comet tail.

Pure DNA can be stored in TE (pH 8) at 4°C for several months. However, traditionally, storage of DNA under ethanol at —20°C has been preferred for long-term storage (years). If subjected to repeated freeze and thaw, an aqueous solution of DNA can lead to single- and double-strand breaks. Hence storing aliquots in a freezer at —20°C (frost-free) or —80°C is another preferred method for long-term storage. 

Yam Tensile properties Specimens with gauge length of 100 mm were tested after being conditioned in a standard atmosphere for 48 hours. Breaking load [N] and strain [%] in single strand knotted and laced form were determined on yams subjected to tensile testing at 60%/min acconlii to the ASTM D 2101 Standard [3]. 

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