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. 2021 Jan 25;10:e55701. doi: 10.7554/eLife.55701

Figure 4. Mutations in clh-1 affect chloride dynamics of ASER in response to salt down-step stimulus.

(a–e) Representative current traces from Xenopus oocytes that expressed cRNA for mock (a), clh-1(wt) (b), clh-1(pe572) (c), and clh-1(pe577) (d) clamped at voltages ranging from −160 mV to 80 mV and perfused at pH 7 with Cl- as the dominant extracellular anion. (e) The current-voltage relationships of mock (triangle, n = 7), clh-1(wt) (circle, n = 20), clh-1(pe572) (diamond, n = 13) and clh-1(pe577) (square, n = 16). The error bars represent s.e.m. (f) Responses of SuperClomeleon expressed in ASER after cultivation at 0 mM NaCl in the presence of food. External NaCl concentration was shifted from 50 mM to 25 mM at time 50 s. Note that the scale of the vertical axis is inverted so that increase in chloride concentration is displayed as up-shift of traces. A and B indicate the time points for calculating R/R0 changes. The shaded region represents s.e.m., n ≧ 17 animals. (g) R/R0 changes upon salt decrease. Mean +/- s.e.m., dots represent individual trials. n ≧ 17 animals, Tukey’s test, ***p<0.001, *p<0.05, compared with wild type. +p<0.05, compared with clh-1(pe572) mutant.

Figure 4.

Figure 4—figure supplement 1. Extracellular pH-sensitivity and bicarbonate permeability of CLH-1.

Figure 4—figure supplement 1.

(a–i) Representative current traces from Xenopus oocytes that expressed cRNA for clh-1(wt) (a–c), clh-1(pe572) (d–f), or clh-1(pe577) (g–i). Oocytes were perfused at pH 7 with Cl- as the dominant extracellular anion (a, c, d), pH 5 with Cl- (b, e, h), or pH 7 with HCO3- (c, f, i). See Materials and methods for details. The oocytes were clamped at voltages ranging from −140 mV to 80 mV. (j–l) The averaged current-voltage relationships of clh-1(wt) (j, n ≧ 16), clh-1(pe572) (k, n ≧ 16), clh-1(pe577) (l, n = 8), at pH 7 with Cl- (circle), at pH 5 with Cl- (diamond), and at pH 7 with HCO3- (square). The error bars represent s.e.m. Trials of the different conditions were performed using the same oocyte.
Figure 4—figure supplement 2. Mutant CLH-1 channels retained pH sensitivity and bicarbonate permeability.

Figure 4—figure supplement 2.

(a–c) Comparison of current amplitudes at −130 mV between pH 7 and pH 5. clh-1(wt) (a, n = 20), clh-1(pe572) (b, n = 18), and clh-1(pe577) (c, n = 8). Two-tailed paired t-test, ***p<0.001, **p<0.01.