Growth conditions

S. pombe cells were cultivated in YPD (rich medium) or EMM2 (minimal medium) (Moreno et al. 1991) supplemented with extra MnCl₂, MnSO₄, or CaCl₂ as indicated. For Mn²⁺ deprivation, MnSO₄ (original concentration; 2.6 μM) was removed from the recipe for EMM2 medium. To prepare EMM2 medium devoid of Ca²⁺, 0.1 mM CaCl₂ and 2.1 μM calcium pantothenate were deleted from the recipe for EMM2. For the change from normal EMM2 to Mn²⁺-deprived or extra Mn²⁺-containing media, cells cultivated in normal EMM2 at 26° were harvested by vacuum filtration, washed in the target liquid media twice on the membrane, and transferred to the new media at 26° for 24 hr. For nitrogen starvation, cells were first cultured in normal EMM2 at 26° and then transferred to nitrogen-deficient EMM2-N medium at 26° for 24 hr (Sajiki et al. 2009). Cell viability was calculated as a percentage of the number of colonies formed vs. the number of plated cells. Numbers of liquid-cultured cells were counted using a Multisizer 3 (Beckman Coulter).