When 10° stripes were presented, GH146/TNT flies walked randomly, whereas CS, GH146, and TNT controls showed normal fixation behavior (Fig. Regarding landmark fixation, GH146/TNT flies were tested for their ability to detect stationary objects of different width. In addition optomotor responses in walking were absent for two different stimuli (24° pattern wavelength, 3 Hz contrast frequency, and 360° pattern wavelength, 0.2 Hz contrast frequency), and GH146/TNT flies show no visually induced landing response (data not shown). GH146/TNT flies showed no head roll response to a grating of moving stripes (60° pattern wavelength, 1.2 Hz contrast frequency) (Fig. To study the function of TeTxLC-expressing neurons in the visual system (see above), we investigated visually induced head roll and landmark fixation in walking. We note the complete absence of label in olfactory and gustatory receptor neurons. 1 A and I), as shown by the binding pattern of the glial-specific Repo antibody ( 28) (data not shown). Expression occurs also in glial cells along all major peripheral nerves (Fig.
1 B and F), and ( v) a single descending interneuron with arborizations in the leg neuromeres (not shown). 1 A, B, F, and G)-and of neurons arborizing in one layer of the proximal medulla and lobula, as well as in specific lobula plate layers, ( iv) a few bilateral neurons in the posterior brain (Fig. 1 A, E, and H), ( iii) a subset of lamina monopolar cells projecting to three medulla layers-most likely L1 and L2 (Fig. 1 A and D) and fibers toward the antennocerebral tract, ( ii) a small set of MB interneurons (Fig. Only few additional elements are labeled by GH146 in the adult: ( i) two to three interneurons with cell bodies near the LPR (Fig. Three lines of evidence suggest that the labeled PNs represent the majority of this cell type in Drosophila: ( i) the presence of stained arbors in most of the glomeruli, ( ii) the tight labeling of the antennocerebral tract, and ( iii) an extrapolation from the known numbers of PNs per glomerulus in other insects ( 16). The remaining 5–10 labeled PNs are mostly of the polyglomerular type, whose fibers bypass the calyx and extend directly to the LPR ( 27). 1 A–E) ( 26) and send their axon via the antennocerebral tract to the MB calyx and the LPR (Fig. Roughly 90 of them establish dendritic arborizations in one of the 43 AL glomeruli (Fig. The most intensely stained brain elements of line GH146 are about 100 PNs of the AL ( 16).
(Bars = 100 μm.) Materials and Methods Drosophila Strains. B–D are assembled from two to three sections each.
( A) Whole mount, ( B–F, H, I) transverse cryosections, ( G) horizontal cryosection. All peripheral nerves exhibit glial expression ( A, arrows) including those within the antenna ( I, arrows). Additional expression occurs in a few MB interneurons ( A, E, H, mbs), in scattered bilateral neurons ( B, F, asterisks), in a subset of lamina monopolar cells ( A, B, F, G, arrowheads) projecting to three layers of the medulla ( G, lower arrowheads), and in unidentified neurons arborizing in the lobula and lobula plate ( G, weak label in neuropil on bottom). ( E, F) Close-ups of glomerular arborizations, and target regions of PNs, respectively. GH146 shows strong expression in projection neurons (pns), which connect antennal lobe glomeruli (gl) via the antennocerebral tract (act) with the mushroom body calyx (cx) and the lateral protocerebrum (lpr). A–D), although the latter seems weaker, very likely because of the lower affinity of the TNT antiserum. lacZ, TAU, and TeTxLC patterns look similar (cf. In C, TAU and TeTxLC are coexpressed (TeTxLC pattern not shown). Figure 1 Adult expression pattern of P line GH146 as visualized by lacZ ( A), TAU ( B, C, E–I), and TeTxLC ( D) reporters.
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