Fig. 1. Grain is expressed in ISN motoneurons and in subsets of interneurons. Stage 14 (A-H) and stage 12 (I) embryos stained for Grn (A,E,I), Repo (I), ß-gal (A,C,E,G) and Myc (B,C,D,F,G,H). Dorsal (A-D,I), mid-dorsal (C') and intermediate (E-H) focal planes of the VNC. Anterior is upwards in all panels. Grn expression within one (C,C',I), two (A,E) or three (B,C,F-H) segments. grn^lacZ is expressed in all Grn-positive neurons (A,E). We noticed consistently weaker expression of Grn and grn^lacZ (or grn^GAL4) in the RP2 motoneuron (arrowhead) compared with other grn-expressing neurons (A,D). Mutually exclusive expression patterns of grn^GAL4/UAS-lacZ with islet-mycEGFP (B,F), and with Hb9-GAL4 (C,C',G) in subsets of motoneurons and interneurons. Overlap of Grn with Eve and Zfh1 in aCC, RP2 (D) and the U motoneurons (asterisks, H). The pCC interneuron, which is located posterior to aCC does not express grn^lacZ (A) or Grn (D). In stage 12 embryos, we find overlap of Grn and Repo (I) in one glia cell (^*). This glia cell rapidly becomes Grn negative at later stages (compare with A1) but maintains ß-gal expression when probed with grn^lacZ (A2) probably owing to the stability of the ß-gal protein. (J) Schematic showing grn-expressing cells in the VNC and the grn-expressing ISN motor axon projections in the periphery. The five U motoneurons are depicted in dark brown.