Researchers studied how magic mushrooms (Psilocybe mexicana) control their chemical processes to make psilocybin. They found that when mushrooms start producing psilocybin, they turn on genes that make more of an amino acid called tryptophan, while turning off genes that would break it down. They also discovered and studied an enzyme that helps control tryptophan use. This understanding could help grow these mushrooms with more consistent psilocybin levels for legitimate medical research into treating depression.