Table 1.
Buffers used in the Pseudo-Null Point pH determination experiment.
| Buffer | Composition | Pseudo-Null pH |
| (BA=butyric acid; TA=trimethyl amine) | ||
| S1 | 3 mM BA/48 mM TA in SPB buffer, pH 7.0 | 7.6 |
| S2 | 3 mM BA/12 mM TA in SPB buffer, pH 7.0 | 7.3 |
| S3 | 3 mM BA/3 mM TA in SPB buffer, pH 7.0 | 7.0 |
| S4 | 12 mM BA/3 mM TA in SPB buffer, pH 7.0 | 6.7 |
| S5 | 48 mM BA/3 mM TA in SPB buffer, pH 7.0 | 6.3 |
| S6 | SPB buffer, pH 7.0 | low osmolarity control |
| S1S | S 1/400 mM sorbitol | 7.6 |
| S2S | S2/400 mM sorbitol | 7.3 |
| S3S | S3/400 mM sorbitol | 7.0 |
| S4S | S4/400 mM sorbitol | 6.7 |
| S5S | S5/400 mM sorbitol | 6.3 |
| S6S | S6/400 mM sorbitol | high osmolarity control |
Calibration of BCECF fluorescence emission ratios was performed according to the Pseudo-Null calibration method for human cell lines [25], with modifications for Dictyostelium cells. The Pseudo-Null pH values were calculated by the formula: pH Pseudo-Null = pHbuffer* log (c(Base)/c(Acid)).