Measurement of Viscous and Elastic Components of Native DNA Fiber Following Carcinogen Administration
The problem of determining the physical properties of giant DNA molecules in native conditions from intact mammalian nuclei (or cells) remains one of the most challenging and intriguing, especially considering their critical dependence on cell proliferation and transformation: DNA length (1), structure (2), and intrinsic viscosity (3) have been shown to be critically related to early events occurring during chemical carcinogenesis. Progressively lower amounts of “putative” single DNA strand breaks are detectable by alkaline sucrose gradients (1), alkaline elution (4), and viscometry (3), but numerous questions concerning the role of higher order structure (dealt with in a separate communication (5)) or the relative contribution of elastic and viscous components on the latter more sensitive viscoelastic measurements remain unanswered. Mammalian DNA molecules “in situ” have a pronounced tendency to associate to form gelled networks of nucleofilament fibers (2) with high elastic modulus and intrinsic viscosity which lend themselves to quantitative measurements (6,7).
KeywordsIntrinsic Viscosity Outer Cylinder Chemical Carcinogen Elastic Component Chemical Carcinogenesis
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