Figure 3.

Simultaneous turgor pressure measurement with a cell pressure probe and a pico gauge. The four frames are taken from Supplemental Movie S3. A, The tips of a cell pressure probe (top pipette) and a pico gauge (bottom pipette) are located at the cell wall of an onion epidermis cell. The oil/water interfaces in the cell pressure probe (solid arrow) and the pico gauge (dashed arrow) are well visible. B, Impalement of the cell pressure probe leads to inflow of cell fluid into the tip and pushes the interface out of the visible area. C, Adjustment of the pressure via the piston increases the pressure in the probe, forcing cell sap back into the cell. The probe pressure is adjusted until the meniscus is stationary, and the pressure reading is taken. D, Impalement of the pico gauge leads to a slight compression of the oil, which is indicated by an instant movement of the oil/water interface. Bars = 25 μm.