Availability of ion specific fluorescent dyes has enabled the possibility to perform in vivo ion specific measurements using live cell imaging in many cellular compartments (Krebs et al., 2010; Bassil et al., 2011; Halperin and Lynch, 2003; Swanson et al., 2011; O'Connor and Silver, 2007). The importance of ion and pH homeostasis of intracellular compartments, including the vacuole, to cell growth is critical and well established (Krebs et al., 2010; Bassil et al., 2011).* Dedicated to Stephen Halperin who tragically and unexpectedly passed away.
