Fig. 1. mls-2 and vab-3 regulate the development of ventral and dorsal CEPsh glia, respectively. (A) The C. elegans head. In all figures, dorsal is up and anterior is left. Posterior regions of ventral CEPsh glia ensheath the ventral ganglion. (B,C) Fluorescence images of a wild-type adult expressing hlh-17::GFP in CEPsh glia (white arrowheads) and the T08G3.3::RFP ADF neuron reporter (yellow arrowheads). (B) Overlay. (C) ADF alone. White arrows, ADF axon. (D) Dendogram depicting similarity of HLH-17 to Olig and other human and C. elegans bHLH protein subfamilies. (E) C. elegans hlh-17 gene structure. Boxes, exons; -shaped lines, introns; arrow, position of a previously predicted translation start site different from that described here (see Materials and methods); TTTTCAG, trans-splicing site; the bHLH domain is in blue. (F-N) Fluorescence (F,G,I,J,L,M) and merged DIC/fluorescence (H,K,N) images of wild-type (F-H), mls-2(ns156) (I-K) and vab-3(ns157) (L-N) adults expressing hlh-17::GFP and ptr-10::myrRFP. White and yellow arrowheads indicate dorsal and ventral CEPsh glia, respectively. Asterisks indicate non-CEPsh glia. Scale bars: 5 µm.