RELEVANCE OF EMPIRICAL OPTIMIZATION FOR CROSS-LINKING DNA BY USING ANORDINARY ULTRAVIOLET-LIGHT SOURCE

For cross-linking DNA onto nitrocellulose or nylon membranes by using ordinary ultraviolet (UV) light, empirical optimization with respect t o exposure time is crucial for obtaining complete hybridization signal s. Longer than optimal UV exposure reduces the signal intensity partic ularly in the larger DNA fragments, whereas shorter exposure due to in sufficient immobilization produces incomplete signals. Relevance of us ing ordinary source of UV light with respect to fixing DNA on a large number of circular filters during library screening is discussed.