Surely freezing would release all the enzymes that happened to be present at the time? How would you guarantee that Tyr hydroxylase and COMT would get a look in? If, through a stroke of luck, freezing temperatures prove to be a trigger for gene expression of the target enzymes this could then be a winner.

Considering the way the CAM metabolism works - the cacti absorb CO2 at night to form malic acid and, it is claimed, the pH balance is maintained through the formation of alkaloids - it appears that darkness would have a particular set of triggering effects on gene expression. It would be worth checking to see whether any studies exist on the effect of low temperatures on gene expression in mescaline-producing cacti. This could inform any decisions made on the rate and degree of cooling used during a nutritionally supplemented cactus freezing experiment.