Interactions of Notch with factors of the MRN. (A-C) aNotch2 expression in the central DM (brackets, left panels) promotes transcription of Id2 (A, N = 4), Id3 (B, N = 2) and FoxC2 (C, N = 3) compared to the contralateral sides. (D-G) Id2, Id3 and Pax7 affect Notch signaling. Dorsal views of whole-mount segments. (D) Basal activity of Hes1 reporter in the lateral DM (N = 21). Id2 (E) or Id3 (F) missexpression enhances Hes1 reporter activity (N = 13 and 8, respectively), whereas Pax7 inhibits signaling (G, N = 13). (D’-G’) Control RFP shows similar electroporation efficiency in all treatments. (H-K) Notch-induced EMT requires Snail1 activity. (H, H’) Cells co-electroporated with control-GFP and control scrambled siRNA are mostly found within the lateral DM with a few cells delaminating from the epithelial sheet 16 hours post-treatment (N = 7). (I, I’) aNotch2 induces labeled cells to undergo EMT and migrate towards blood vessels (N = 6). (J, J’) Snail1 knock-down maintains cells within the lateral DM, inhibiting delamination (N = 5). (K, K’) Snail1 knock-down hinders Notch-induced EMT, as transfected cells remain epithelial within the lateral DM (N = 4). Bar: (A-C) 100 μm, (H-K) 50 μm. CV, cardinal vein; DM, dermomyotome; EMT, epithelial-to-mesenchymal transition; EP, electroporation; ISH, in situ hybridization; RFP, red fluorescent protein.