A simple enzymatic screening method has been developed to detect whether a tissue sample has been preserved with formalin or with ethanol only because such a method is a useful tool for predicting the quality of genetic test results. The method is based on enzymatic digestion at 55°C at neutral pH. The screening method shows that only ethanol-preserved tissue samples are dissolved, whereas formalin-preserved samples remain undissolved. The method was developed by the incorporation of laboratory rats preserved under controlled conditions in either 4% neutral buffered formalin or 96% ethanol. The method was subsequently tested on wild-living preserved specimens and an archived specimen. The protease enzyme used was Savinase® 16 L, Type EX from Novozymes A/S. The enzymatic screening test demands only simple laboratory equipment. The method is useful for natural history collections in museums where DNA analyses of archived specimens are performed. Wasted time and resources can be avoided through the detection of formalin-fixed specimens because these specimens yield low-quality, damaged DNA. In addition to the screening method, it is shown that formalin-preserved specimens can be macerated by enzymatic digestion under alkaline conditions at 55°C.

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Author notes

Associate Editor.—Christine Johnson