In case you were wondering a bit more specifically about Claudius and the mushrooms, an MSU press release enlightens (inter alia, of course):
In addition to better understanding how errors are prevented, Burton’s research team also learned ways errors are corrected during rapid RNA synthesis. To learn about error correction, Burton’s team stalled the DNA conveyer belt. They did this using a deadly mushroom toxin, alpha-amanitin.
Alpha-amanitin is the poison of the death cap mushroom, which can be deadly to humans. In 54 A.D., Emperor Tiberius Claudius was fed a death cap mushroom by his wife Agrippina to put her son Nero on the throne of ancient Rome. Alpha-amanitin kills people by stalling movement of the DNA conveyer belt.