Fig. 1. Kv1.5 mediated local V_mem perturbation disrupts endogenous brain development.

(A) Quantification of tadpoles with brain phenotypes upon microinjections of hyperpolarizing Kv1.5 ion channel mRNA in the indicated cells (red arrows) of the four cells Xenopus embryo. A high incidence of misformed brain is observed in dorsal injections in comparison to uninjected controls. A χ² analysis was performed. The dorsally injected embryos were significantly different from the controls (*** p<0.001). Ventral injections were not significantly different from controls. Injections in both dorsal and ventral regions showed decrease in misformed brain in comparison to dorsal injections alone. A t-test showed both dorsally and ventrally co-injected embryos were significantly different from the dorsally injected embryos (***p<0.001). (B) Control (uninjected) and Hyperpolarizing Kv1.5 mRNA injected (red arrows indicate injected cells) in 4-cell PNTub::GFP transgenic Xenopus embryos. (i) Stage 45 PNTub::GFP controls show GFP fluorescence in the neural tissue. The uninjected control tadpoles show well-formed anterior neural tissues. Control tadpoles show well-formed anterior neural tissue with red arrowheads indicating nostrils, orange arrowheads indicating forebrain/olfactory bulbs, yellow arrowheads indicating mid-brain and green arrowheads indicating hindbrain. (ii-vii) Stage 45 PNTub::GFP transgenic tadpoles dorsally injected with hyperpolarizing channel Kv1.5 mRNA. Solid Blue arrowheads indicate severely malformed midbrain and forebrain. Empty blue arrows indicate eyes which are also found to be malformed or absent. (viii) Stage 45 PNTub::GFP transgenic tadpoles injected with hyperpolarizing channel Kv1.5 mRNA in both dorsal and ventral blastomeres showing brain structure similar to the uninjected controls (i). Gut (white arrowhead) is also autofluorescent in the same spectrum.