Figure 7.
Olig3 acts as a transcriptional repressor and cooperates with Mash1 to instruct the dI3 neuronal subtype. Chick spinal cords were electroporated on the right side with mouse Olig3 (A,B), Olig3EnR (D,E), Olig3VP16 (G,H), Mash1 (J,K), Olig3 and Mash1 (M,N), and the effect on the development of neurons was assessed using antibodies against Tlx3 (red) and Isl1 (green) (A,D,G,J,M), and Lhx1/5 (red) and Lbx1 (green) (B,E,H,K,N). The insets in B, E, H, K, and N show the expression of the coelectroporated GFP in the right side of the spinal cord. The brackets in A indicate dI3 and dI5 neurons, and the brackets in B point to dI2 and dI4-dI6 neurons. The bracket in M highlights the increased numbers of dI3 neurons. The quantification of the neuronal subtypes generated in the electroporated and the control side of the spinal cord are shown in C, F, I, L, and O. For this, numbers for various neuronal subtypes were counted; the data are displayed as the ratio of neuron numbers generated on the electroporated side and the control side. A ratio of 1 indicates no effect, a value <1 indicates a suppression, and a value >1 indicates an induction of a particular neuronal subtype. Bar, 100 μm.