Fig. 2: DspE and AvrE activities in Xenopus oocytes and liposome.
From: Bacterial pathogens deliver water- and solute-permeable channels to plant cells
a, Schematic of the three oocyte assays, showing details for the two-electrode voltage clamp (TEVC) to test ion conductance (bottom left) (Vc, voltage command; Re, electrode resistance; Rm, membrane resistance; and Cm, membrane capacitance), the baseline and induced swelling and burst assay to test water conductance (bottom middle) and dye uptake to test conductance to molecules larger than single ions (bottom right). b,c, DspE and AvrE induce ion currents in the two-electrode voltage clamp assay. Mean ± s.e.m. (n = 5 oocytes) current values at different test pulses from oocytes expressing DspE (0.01 ng cRNA per oocyte) or AvrE (0.1 ng cRNA per oocyte) were recorded. d, DspE (2 ng) and AvrE (20 ng) induced fast oocyte swelling and burst at 24 h after cRNA injection when placed in a low-osmolarity (40 mOsm) solution. The data are presented as mean ± s.e.m. (n = 5 oocytes) of increased oocyte volume in relation to its initial volume. e,f, Fluorescein or eGFP entry assays. Oocytes injected with 2 ng dspE (e) or 20 ng avrE (f) cRNA or injected with water were incubated for 20 h in bath saline with or without fluorescein or eGFP. Values of fluorescence intensity were subtracted from the background and are presented as mean ± s.e.m. (n = 5 oocytes) corrected ‘total cell fluorescence’. a.u., arbitrary units. g, Schematic of DspE-dependent release of carboxyfluorescein (CF) encapsulated within a liposome. h, Fluorescence increased over time for carboxyfluorescein-loaded liposome after addition of wild-type (WT) DspE (yellow), DspE(Δβ-barrel) (blue) or buffer (grey). The result is representative of three experimental replicates. P values were calculated using two-way analysis of variance (ANOVA; b,c,e,f) or two-way repeated measures ANOVA (d).
