Extended Data Fig 6 |. Lysosomal pH of salt stressed worms.

a. PAGE analysis of the I-switch-based pH reporter module denoted Br-I-switch⁵⁹. D_D strand has Alexa488N as a donor dye and D_A strand has Alexa647N as acceptor dye. b. pH calibration curve of Br-I-switch shows ~20 fold change of D/A signal from pH 5.0 to 6.0, with highest sensitivity near pH 5.5 which is the pH of coelomocyte lysosome³⁸. c. pH measurement of single lysosome of N2 and nhx-5(−) worms in normal salt (NS) and acutely salt stressed (Ac) condition. nhx-5(−) has lower pH in both NS and Ac conditions. *P ≤ 0.05; **P ≤ 0.01; ***P ≤ 0.001; ns, no statistical significance by two sample t-test. d. Representative images of Br- I-switch in Donor (D), acceptor (A) FRET (D/A) channels and calculated pH heatmaps.