Shotgun sequencing of ancient RNA from Late Pleistocene and historical canids shows tissue-specific transcriptome survival

While the recovery and sequencing of ancient DNA from archaeological material is now commonplace, very few attempts to generate ancient transcriptomes have been made. This is presumably due to the assumption that RNA is too unstable for extended survival, particularly when dealing with mammalian tissues considering the abundance of nucleases released during autolysis. However, given the recent successes in sequencing ancient RNA (aRNA) from various archaeological sources, we suspect that these assumptions surrounding mammalian tissues may be incorrect or exaggerated. Therefore we attempted to challenge the underlying dogma, by generating shotgun sequencing RNA data from sources which would otherwise be considered unviable for such study. This project represents aRNA data generated from two historical wolf skins, and liver tissue of a 14,300-year-old Pleistocene canid. Not only is the latter the oldest ever RNA to be sequenced in any form, but also shows evidence of tissue-specificity and thus confirms its authenticity. These observations show not only that aRNA can survive for extended periods in mammalian tissues, but also that it has potential for tissue identification, and possibly further uses, when sequenced using high-throughput technology.