Avidin DN, 1 mg, is isolated by an affinity chromatographic system that results in a form of avidin which, like Avidin DH, exhibits very low non-specific binding to nucleic acids. Although the reasons for this property are not fully understood, this feature can be exploited when using biotin-avidin detection systems with biotin-labeled DNA or RNA probes for in situ or nitrocellulose hybridization techniques.