Figure 5
From: Spinal neurons require Islet1 for subtype-specific differentiation of electrical excitability
In E3 morphants, Rohon-Beard-like cells have electrical properties that resemble those of dorsal lateral ascending interneurons and dorsal commissural interneurons. (A) In uninjected embryos, RB whole-cell inward current (INa/Ca) is of larger amplitude than that of dorsal lateral ascending interneurons (DoLA) or dorsal commissural interneurons (Dorsal Comm). (B) In CtlMO injected embryos, RBs have INa/Ca amplitude that resembles that of RBs in uninjected embryos (see A). However, INa/Ca amplitude of RB-like cells in E3 morphants is smaller than that of control RBs. In contrast, DoLAs in uninjected (A) and E3 morphants have similar inward current amplitudes. (C) RBs of control embryos have significantly larger inward current density than do dorsal interneurons (*P < 0.001 versus RB). The inward current densities of interneurons in control and E3 morphant embryos are not significantly different from each other. However, INa/Ca density of RB-like cells is significantly smaller than that of control RBs (*P < 0.001 versus RB) and instead resembles that of DoLAs in control or E3 morphant embryos. In contrast, INa/Ca density of RB-like cells is significantly larger than that of Dorsal Comm interneurons (†P < 0.05 versus Dorsal Comm). (D) In uninjected embryos, whole-cell outward current (IKv/Ca) amplitude of RB neurons is larger than that of dorsal interneurons. (E) RB-like neurons have smaller amplitude IKv/Ca than do control RBs in uninjected (D) or CtlMO injected embryos (E). In contrast, knock-down of Islet1 has no effect on IKv/Ca amplitude recorded from DoLAs (E). (F) Steady-state IKv/Ca density of RBs is significantly larger than that of neighboring interneurons (*P < 0.001 versus RB) or of RB-like cells (†P < 0.05 versus RB) or DoLAs (#P < 0.01 versus RB) in E3 morphants. Current densities of the DoLA and Dorsal Comm interneurons are not significantly different from each other.