PMC

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.

Hydraulic scheme of digital valve test system. 1. Oil suction filter. 2. Main oil pump. 3. Motor. 4. High pressure filter. 5. Proportional overflow valve. 6. Check valve. 7. Pressure gauge. 8. Stop valve. 9. Accumulator. 10. Stop valve. 11. Temperature sensor. 12. Pressure sensor. 13. Micro high speed digital valve. 14. Pressure sensor. 15. Flowmeter. 16. Accumulator. 17. Stop valve. 18. Solenoid on-off valve. 19. Check valve. 20. Pressure gauge. 21. Throttle valve. 22. Check valve. 23. Proportional overflow valve. 24. High pressure filter. 25. Motor. 26. Auxiliary pump. 27. Oil suction filter.

Pico gauge pressure measurement in sieve element and fungal cells. A to D, Four frames extracted from Supplemental Movie S5. A, A pico gauge tip is located in front of a sieve element with a sieve plate (angled arrow) and a forisome in the low-volume state (dashed arrow), indicating uninjured conditions. The oil/water interface in the pico gauge is marked by the solid arrow. B, Impalement of the pico gauge into the sieve element leads to an instant compression of the oil, which provides the pressure reading. C and D, The forisome switches into the high-volume state within 1 s, but the measurement is already completed before the forisome blocks the tube. E and F, Two frames extracted from Supplemental Movie S6 showing a pico gauge measurement in a fungal hyphae cell with a volume of only about 900 fL. The compression of the pico gauge fluid is minor (23 fL) but sufficient for a pressure calculation. The oil/water interface is shown by the arrows. Bars = 25 μm.

Oil displacement experimental apparatus. 1 Constant-flux pump. 2 Accumulator; 3 Six-way valve. 4 Pressure gauge; 5 Core holder. 6 Oil-water separation pipe. 7 Constant-temperature oven.