Galactose-induced HSP104 overexpression
Yeast cells transformed with either pYES2, pUKC1831, pUKC2200 or pUKC2212 were grown for 14–16 h at 30 °C in YNB/glucose-based minimal medium lacking uracil to allow for selection of the URA3-based plasmids. The cells were then resuspended in a pre-induction medium (0.67% YNB without amino acids, 2% raffinose with complete supplement minus uracil; YNBRaf) to give a starting OD600 = 0.1. The culture was then grown at 30 °C with aeration until OD600 ≈ 0.5 was reached. Filter-sterilized galactose solution (20%) was then added to a final concentration of 2% w/v (YNBGal) and the culture incubated for a further 6 h. 1 ml each culture was then used to inoculate fresh YNBGal medium and this was incubated for a further 18 h (to give a t = 24 h time point). This was repeated to give a 48 h time point. At each time point an appropriately diluted culture sample was plated in triplicate onto one-quarter YEPD to determine the viable cell number and the percentage of [psi−] cells at the time of plating.