Figure 4.

Segregation of ψ⁺ and ψ^- in mother-daughter pairs taken from a culture growing in guanidine hydrochloride in which only 67% of the cells remained ψ⁺ . Budded cells were selected by micromanipulation on a YEPD agar plate and the daughter bud separated from the mother, each being left to grow into a colony at a marked place on the plate. The third pair illustrates segregation of ψ⁺ from ψ^- both in the chosen pair of cells and at the next division of the mother cell. It is evident that the ψ⁺ prion remained in the mother at the first division, as it did in 93% of the mother daughter pairs taken from this culture.