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Consumption of alcohol injures DNA, and such damage is considered to be a primary cause for the development of cancer and many other diseases essentially due to reactive oxygen species generated from alcohol. To sensitively detect alcohol-induced DNA lesions in a biological system, we introduced a novel analytical platform for visualization of single genomic DNA molecules using E. coli. By fluorescently labelling the DNA lesions, our approach demonstrated, with the highest sensitivity, that we could count the number of DNA lesions induced by alcohol metabolism in a single bacterial cell. Moreover, our results showed a linear relationship between ethanol concentration and the number of DNA lesions: 0.88 lesions per 1% ethanol. Using this approach, we quantitatively analysed the DNA damage induced by exposure to alcoholic beverages such as beer (5% ethanol), rice wine (13%), soju (20%), and whisky (40%). [ABSTRACT FROM AUTHOR]

We present a single molecule visualization approach for the quantitative analysis of reactive oxygen species (ROS) induced DNA damage, such as base oxidation and single stranded breaks in large DNA molecules. We utilized the Fenton reaction to generate DNA damage with subsequent enzymatic treatment using a mixture of three types of glycosylases to remove oxidized bases, and then fluorescent labeling on damaged lesions via nick translation. This single molecule analytical platform provided the capability to count one or two damaged sites per λ DNA molecule (48.5 kb), which were reliably dependent on the concentrations of hydrogen peroxide and ferrous ion at the micromolar level. More importantly, the labeled damaged sites that were visualized under a microscope provided positional information, which offered the capability of comparing DNA damaged sites with the in silico genomic map to reveal sequence specificity that GTGR is more sensitive to oxidative damage. Consequently, single DNA molecule analysis provides a sensitive analytical platform for ROS-induced DNA damage and suggests an interesting biochemical insight that the genome primarily active during the lysogenic cycle may have less probability for oxidative DNA damage. [ABSTRACT FROM AUTHOR]

Ultraviolet radiation induced DNA damage such as double stranded breaks and single stranded breaks is visualized at the level of single DNA molecules. Molecular observations provide a map of DNA radiation-mediated breakages, revealing the sequence dependency of DNA damage rather than random occurrences. [ABSTRACT FROM AUTHOR]

The formation of carbon nanotubes (CNTs) through precipitated carbons emerging from supersaturated metal catalysts is an established mechanism for their growth during the CVD process. Here, the CNT growth mode is determined by the interaction between the substrate and the catalyst nanoparticle, e.g., the tip-growth mode for the weak adhesion between them and the base-growth mode for the strong adhesion case. With microscopic evidence, this study reports another factor that governs the growth mode of CNTs on carbon-based substrates. Catalyst nanoparticles after only sputtering and annealing processes before the chemical vapor deposition (CVD) process are fully or partially wrapped with some graphitic layers, which are formed by carbons escaping from the carbon substrate. The formation of the wrapping graphitic layers is initiated by catalyst atoms diffusing into the carbon substrate during the catalyst sputtering process. The diffused catalyst atoms later coalesce into the nanoparticles, during which carbon atoms escape from the carbon substrate, forming the graphitic layers which wrap around the catalyst nanoparticles for energy minimization. Then, the carbon atoms generated from the catalytic reactions during the CVD process interact with the carbons in the graphitic layers wrapped around the catalyst nanoparticles, bringing about clear tip-growth of CNTs on carbon-based substrates and a stable interface (carbon-carbon bonding) between CNTs and carbon-based substrates.