Fig. 4. Glial expression of transgenic Rho1 disrupts migration and nerve ensheathement. repo:GAL4 embryos carrying the UAS-actin-GFP marker were used as the wild type (A-C). The repo::actin-GFP flies were also crossed to lines carrying UAS-RhoAV14 (D-F), UAS-RhoAwt (G-I) and UAS-RhoAN19 (J-L). Embryos were stained with anti-GFP (green) and mAb 22C10 (red). (A,D,G,J) Green channels. (B,E,H,K) Red channels. (C,F,I,L) Merge. Anterior is to the top, CNS is to the left. Embryos are stage 16. (A) Wild-type peripheral glial actin-GFP staining includes vPG cell (concave arrow), lateral line glia (arrowheads) and lateral chordotonal glia (asterisk). (D) RhoAV14 expression in glia results in glial stalling at the CNS/PNS transition zone (compare with A). Large tracts of PNS nerves are not ensheathed by the glia (arrow). The lateral line glia fail to extend processes to interconnect across hemisegments (arrowheads). Long spike-like projections emanate from the glia (concave arrows). The lateral chordotonal glia are small and rounded (compare asterisk in D with those in A and G); however, the underlying sensory neurons are relatively normal (asterisk in E). (E) The sensory axons are defasciculated (arrow) as a result of glial RhoAV14 expression. (F) The spike-like projections of peripheral glia due to RhoAV14 expression do not always correspond with axonal tracts (concave arrow). (G) Ectopic wild type RhoA expression in glia disrupts nerve wrapping profile (compare with A) and results in breaks in the glial sheath (arrows). (J) Expression of RhoAN19 disrupts glial wrapping profile and prevents vPG cell (concave arrow) from separating from main nerve branch. (H,K) Sensory axon defasciculation (arrows) in RhoAwt and RhoAN19 embryos indicates that glia do not effectively wrap the axon tracts.