A simple technique for the isolation of very high molecular weight genomic DNA from animal tissues and cells is described. The method involves rapid isolation of nuclei and their embedding in agarose beads followed by extraction of lipids and proteins. Similar amounts of DNA were retrieved from skin and muscle samples over time, but more complete STR profiles were obtained from muscle. Although higher amounts of DNA were recovered from tissue samples than from the surrounding preservative, the average number of reportable alleles from the “free DNA” was comparable. Students add alcohol, which floats on top of the water, to lift the DNA out of the water and to separate it from the rest of the cell debris. Since the DNA does not dissolve in alcohol, it precipitates (turns to a solid) in the alcohol layer. Ethanol or isopropyl alcohol causes the DNA to precipitate. When DNA comes out of solution it tends to clump together, which makes it visible. The long strands of DNA will wrap around the stirrer or transfer pipet when it is swirled at the interface between the two layers.

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