Use of quantitative polymerase chain reaction analysis to compare quantity and stability of isolated murine DNA.

Deoxyribonucleic acid (DNA) can be extracted from different tissue sources for genotyping of mice. Methods of collecting tissue vary with respect to their perceived invasiveness, and in some cases, tissue is collected multiple times in order to verify a genotype. The authors' goal was to refine and optimize tissue collection methods with quantitative measures for subsequent genotyping. To do this, the authors used real-time quantitative polymerase chain reaction (qPCR) analysis to quantify DNA extracted from fecal pellets, hair, buccal swab samples, ear punch samples and tail biopsy samples and then compared the quantities of DNA obtained by using either previously published protocols or commercial kits to extract DNA. They found that 2-mm tail biopsy samples yielded significantly more DNA than did the other sources and that commercial extraction kits generally yielded more DNA than did published protocols. The authors also assessed the stability of DNA extracted from the various tissue sources by repeating the qPCR analysis after the samples had been frozen and stored for 44 months. Although the quantities of DNA in the stored samples had decreased, all the samples could still be used for PCR-based genotyping. The authors' work supports the collection of a single minimal biopsy sample of 2 mm of tail or ear tissue, above other sources, for highest yield of DNA for genotyping. With appropriate storage, DNA remains usable for PCR-based genotyping for years without a need for repeated animal sampling.