The last-born MNs eliminated by PCD are primed with a specific combination of TFs under control of Imp and Syp.
(A1, B1, C1, E1, F1, G1, I1, J1, K1) Plots of the relative position of each Lin A/15 cell from a lateral perspectives showing the expression of Jim (A1, B1, C1,), RunxA (E1, F1, G1), and Nvy (I1, J1, K1) in purple, orange and green respectively, the Elav+ MNs (blue), the NB (cyan) and the GMC in control (A1, E1, I1,), Imp OE (B1, F1, J1) and Syp RNAi (C1, G1, K1).
(A2-A3, B2-B3, C2-C3, E2-E3, F2-F3, G2-G3, I2-I3, J2-J3, K2-K3) confocal sections showing the expression of Jim (A2-A3, B2-B3, C2-C3,), RunxA (E2-E3, F2-F3, G2-G3,), and Nvy (I2-I3, J2-J3, K2-K3) in RED, the Elav+ MNs (blue), the Dpn+ NB (cyan). The position of the sections are shown in (A1, B1, C1, E1, F1, G1, I1, J1, K1). The asterisk indicate the NBs. Note 1: The arrowhead in B2 indicates a jim+ neuron close to NB, this is never seen in the control LinA/15. Note 2: The arrowheads in E2 indicate RunxA+ neurons close to NB, this is never seen in ImpOE and Syp RNAi LinA/15. Note3: the arrowheads in I2, J2 and K2 indicate NVy + neurons close to the NB, the expression of Nvy is barely detectable in ImpOE and Syp RNAi LinA/15.
(A4, B4, C4, E4, F4, G4, I4, J4, K4) Graphs of the frequency of Jim (A4, B4, C4), RunxA (E4, F4, (G4,) and Nvy (I4, J4, K4) expression as a function of x’ (x’: MN ordering axis according to their relative distance from the NB among >15 specimens before (gray bare) and after (colored lines) applying a Savitzky-Golay filter (see material and methods) in control (A4, E4, I4), Imp OE (B4, F4, J4) and Syp RNAi (C4, G1, K4). The horizontal bar indicates the Jim+ cell cluster detected with the PCCD method.
(D1-D2, H1-H2, L1-L2) Graphs of the number of Elav+ Lin A/15 MNs (D1, H1 and L1) and graphs of the number of Elav+ Lin A/15 MNs expressing Jim (D2), RunxA (H2) and Nvy (L2) in control, Imp OE and Syp RNAi LinA/15.
(M) Schematic of the TF codes expressed in each iMN predicted by the PCCD method in an L3 larva in control, Imp OE and Syp RNAi LinA/15). Bottom: schematic of the cell body of Lin A/15 iMNs. The numbers inside indicate their relative distances from NB. Top: the horizontal bars indicate the TF+ cell clusters detected with the PCCD method. The dotted lines indicate the coverage index at the border (see Materials and Methods).