Expression, localization, and interdependence of IAV and NAN in chordotonal cilia. A, In situ hybridization of an iav antisense RNA probe to embryos at late stage 16. Lateral (lch) and ventral (vch) chordotonal organs are indicated and enlarged in the inset. B-G, Immunostaining of the second antennal segment of wild-type (B, E), iav¹ (C, F), and nan^36a (D, G) with anti-IAV or anti-NAN serum (red). The anti-IAV serum was directed against the N-terminal cytoplasmic region (anti-IAV-N; see Materials and Methods); similar results were seen with an anti-IAV C-terminal antiserum (data not shown). The mAb 22C10 (Zipursky et al., 1984), which labels a neural cytoskeletal protein in the cell bodies and inner segments but not the ciliary outer segments, is shown in green. The arrowheads denote the position of the outer segments.