For practically the whole spring semester and up until recently, a few of my fungal strains have been acting up. It is quite distressing when an experiment you’ve done 10’s to 100’s of times suddenly stops working and you don’t know why. You’ve done everything the same as before, so what gives?! Fungi, being the funky little beings they are, sometimes do odd things if their spores have been in the fridge too long, passaged too many times, or even get a random mutation. We have stocks in out -80C freezer for this very purpose– to start from scratch, so to speak. I don’t vibe with non-fungal organisms, but I think similar things can happen to animal cell lines. I want to say some can lose specially-designed phenotypes, stop dividing, and become genetically unstable.