Yeast directed evolution
An undergraduate course experiment design
I love this simple experiemnt in my Cell Biology course, where we were assigned to design a cell biology experiment and finsih it in a group.
I was inspirated by this PNAS paper entitled “Experimental evolution of multicellularity”. The idea is simple: we can use gravity to select yeast colonies in a culture. For each passage, we separate the cells from the top and the bottom of the centrifuged culture and inoculate them in new medium. After 21 days’ culture we successfully obtain much more “multicellular” yeast in our experiemntal group (the ones in the bottom).
top left: the change of yeast multicellularity in our experiment; top right: the morphology of yeast clusters; bottom left: use trypan blue to figure out the formation of yeast cluster; bottom right: yeast clusters get larger after 21 days' selection