FIG. 1.

Boric acid tolerance of yeast cells. (A) Three different wild-type strains were grown to logarithmic phase in rich (YPD) medium and diluted to an OD₆₀₀ of 0.2, and 5 μl of each cell suspension was spotted on plates containing the indicated amounts of boric acid. The plates were incubated at 30°C for 5 days and photographed. (B) An overnight culture of wild-type yeast (BY4741) was diluted to an OD₆₀₀ of 0.05 and incubated with the indicated amounts of boric acid in YPD medium. Cell growth was monitored by OD₆₀₀ measurements. (C) Wild-type cells (BY4741) were transformed with an empty vector (p426) or with p426-VAN1 or p426-ATR1 plasmid, and the transformants were spotted on YNB plates containing 0, 50, or 100 mM boric acid.