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Fig. 4 | BMC Biology

Fig. 4

From: Optimized photo-stimulation of halorhodopsin for long-term neuronal inhibition

Fig. 4

Wavelength-dependent inactivation and recovery of eNpHR3.0 in X. laevis oocytes. a Sample photo-current traces of eNpHR3.0 upon stimulation for 60 s at 590 nm, 532 nm, or 473 nm at constant intensity (2.6 mW/mm2). b, c Quantification of the initial peak current (Ipeak), the remaining current at the end of illumination (Ilate), and the ratio Ilate/Ipeak. d Ilate/Ipeak upon 60-s-long illumination at 590 nm, 532 nm, or 473 nm at different light intensities (n = 5 cells). e Sample photo-current trace of eNpHR3.0. Inactivation was induced by a 60-s light pulse at 590 nm (2.6 mW/mm2). Recovery was probed by 10-ms light pulses (590 nm, 2.6 mW/mm2) at 1, 5, 10, 20, 40, 60, 120, and 300 s after the initial 60-s illumination. f Quantification of eNpHR3.0 recovery (n = 8 cells). g Peak-scaled sample traces from three different cells demonstrating that blue (473 nm) or violet (400 nm) light (2 s, 1 mW/mm2) accelerates the recovery from inactivation (at 5 s). Note the outward current induced by blue light. h Quantification of recovery as in g. i Peak-scaled sample traces from one oocyte illustrating eNpHR3.0 photo-currents induced by illumination at 590 nm alone (2.6 mW/mm2) or by co-illumination with either 473 nm (1 mW/mm2) or 400 nm (1 mW/mm2). j Quantification of Ilate/Ipeak as in i. k Sample traces from one oocyte illustrating eNpHR3.0 photo-currents induced by illumination at 473 nm alone (6.6 mW/mm2), by co-illumination at 590 nm (2.6 mW/mm2) and 400 nm (1 mW/mm2) or by co-illumination at 532 nm (6.6 mW/mm2) and 400 nm (1 mW/mm2). l, m Quantification of Ipeak, Ilate, and Ilate/Ipeak as in k. All measurements were performed in Ringer’s solution (pH 7.6) at a holding potential of − 40 mV. Data are presented as mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001. c, h, j, m Asterisks indicate significance levels of post hoc t tests with Bonferroni correction following one-way ANOVA (h) or one-way repeated-measures ANOVA (c, j, m)

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