Figure 3

spire expression in the central nervous system and peripheral nervous system of Drosophila embryos. Wild-type embryos were collected, fixed, and analyzed by in situ hybridization with a probe that recognizes all spire isoforms, using alkaline phosphatase detection. Widespread expression of spire was observed in both the peripheral nervous system (PNS) and CNS of wild-type embryos. We did not discern any difference in the pattern of hybridization in lola mutant embryos. We also did not detect any difference in the strength of the spire signal, though this is not surprising given the small magnitude of the effect. (A) Filet preparation of entire embryo (stage 14). PNS and CNS are indicated with brackets. Dorsal, lateral, ventral' and ventral clusters of peripheral sensory organs are indicated as d, l, v' and v, respectively. Anterior is to the left. (B) High magnification view of a lateral sense organ cluster (stage 16) showing preferential expression in the neurons and cap cells of the chordotonal organs. Soma sheath and scolopale cells did not label detectably. (C) spire RNA was detected in many cells of the CNS. The motoneurons RP3 and aCC are indicated (arrows). Two segments are shown.