Identification of animal skin of historical parchments by polymerase chain reaction (PCR)-based methods

This study deals with establishing of a PCR-based strategy with the aim to recognize the animal origin of different historical parchments. This is one of relatively rare studies on the analysis of ancient DNA from parchments. Robustness of the PCR technology is demonstrated by successful identification of the animal species using only a small amount of DNA isolated from 12 parchment samples. Ten PCR-based assays specific for the detection of different animal species (Bos taurus, Ovis aries, Capra hircus, Sus scrofa, Oryctolagus domestica, Cervus elaphus, Capreolus capreolus, Dama dama) and two PCR assays utilizing universal primers were evaluated and optimized with the aim to find a rapid parchment identification method, which would be more reliable than the classical microscopic examination. The optimized PCR methods produced satisfactory results. Out of 12 investigated parchments, 9 items were unambiguously identified, DNA from 2 samples could not be amplified with any of the species-specific PCR assays, and only one parchment produced controversial results. The species-specific PCR results were confirmed by direct sequencing and PCR cloning with consequent sequencing. Our approach, including isolation of parchment DNA by chaotropic solid-phase extraction, optimization of the PCR programs and high-stringency annealing temperatures, demonstrated to be effective, easy and reliable for the analysis of historical parchment DNA. We consider this PCR-based strategy potentially useful also for investigation of other types of animal items conserved in museums, galleries or libraries.