Fig. 5. Spatial expression of selected candidate gcm downstream genes by in situ hybridization and immunocytochemistry. Whole-mount in situ hybridization (A-J,Q,R) and immunostaining (K-T) show expression of differentially regulated genes in wild-type, sca-gcm and gcm mutant embryos. Ventral views of stage 11 (A-D) and stage 15/16 (E,F,I,J,K-P) embryos, and lateral views of stage 15/16 embryos (G,H,Q-T), anterior is towards the left. Fold changes and P values are indicated on the right. (A,B) Expression of htl in stage 11 wild-type embryos is visible in a distinct set of neural precursors; in sca-gcm embryos, htl is expressed throughout the neurogenic region. (C,D) In stage 11 embryos, the scrt gene is expressed in neural precursors; in stage 11 sca-gcm embryos, the expression of scrt is diminished in most of the neural precursors, but is still apparent in a subset of these cells. (E-H) In stage 15/16 wild-type embryos, bnb gene is expressed in lateral glial cells; in stage 15/16 sca-gcm embryos, the expression of bnb increases markedly and appears virtually in all of the cells of the nervous system. (I,J) In stage 15/16 wild-type embryos, the elav gene is expressed in all neurons; in stage 15/16 in sca-gcm embryos, expression of elav is strongly reduced in most of the neurons. (K,L) In stage 15/16 wild-type embryos, the EY protein is expressed in a segmentally reiterated subset of neurons in the CNS; in stage 15/16 sca-gcm embryos, the number of EY-expressing cells in the CNS is dramatically reduced. (M,N) In stage 15/16 wild-type embryos, the TEN-M protein is expressed on the axons that make up the longitudinal and commissural tracts of the CNS; this axonal expression of TEN-M is virtually abolished in stage 15/16 sca-gcm embryos. (O,P) In stage 15/16 wild-type embryos, the WRAPPER protein is expressed in midline glial cells, in some lateral glial cells and in glial cells supporting the chordotonal sensory organs; this expression has spread to the complete CNS region in stage 15/16 sca-gcm embryos. (Q,R) In late stage embryos REPO (brown) is expressed in all and bnb (blue) is expressed in a subset of lateral glial cells; in gcm mutants REPO expression is reduced to a few cells, and bnb expression is completely absent in the CNS. (S,T) In late stage embryos, WRAPPER is expressed in midline glial cells, in some lateral glial cells and in glial cells supporting chordotonal sensory organs (arrowheads); in gcm mutant embryos WRAPPER expression in lateral glia (CNS) and in chordotonal sensory organs (PNS) is absent, whereas expression in midline glial cells remains.