Figure 3.

Photosynthetic oxygen production rescues neuronal activity under hypoxic conditions

(A) Episode (A1) of O₂ concentration recording in the bath chamber (black trace) and IV^th ventricle (green trace) and of concurrent superior oblique nerve spiking and mean firing rate (black trace) at hyperoxic (Carbogen) and hypoxic (Nitrogen) bath O₂ levels during alternating periods of darkness and light in a preparation containing wild-type Synechocystis 6803; note that nerve spiking under hypoxic conditions reversibly ceases in darkness (white arrow heads) but can be restarted during illumination (black arrow heads); insets depict nerve spike discharge under control (A2) and hypoxic conditions in darkness (A3) and light (A4) at higher temporal resolution.

(B–D) Boxplots depicting the delay of discharge cessation under hypoxic conditions in darkness (B), light- or carbogen-induced restart of spiking (C) and magnitudes of re-established firing rates (D) with either C. reinhardtii (green bars) or Synechocystis 6803 (cyan bars) in the vascular system as compared to the firing rate following carbogen-induced restart of spiking (gray/pink bars) in darkness. ∗, p < 0.05, Mann Whitney U-test in (B) and (C), Bonferroni-corrected; Wilcoxon signed-rank test in (D), n.s. not significant.