Drop test experiment: 3 L droplets of plasmid-containing standard yeast suspensions containing about 20 000 ura+ colony-forming units were deposited on the appropriate selective media to allow expression of the HIV-1 integrase in yeast. When the drops had dried, plates were incubated for 3 days, and the effect of integrase expression on yeast was determined by visual observation of the Petri dishes. Lethality is observed when IN is expressed in yeast (2) but not in the presence of empty plasmid (1) or when expressing inactive D116A or E152A IN (3 and 4). JSC302 and W303-1A: RAD52+, W839-5C: identical to W303-1A except for RAD52 gene disruption. AB2: diploid obtained from W303-1A (adapted from [39]).
