Fig. 4.

Nonrandom spatial effects offru¹ on expression of FRU^M in the brain. Pupal progeny of males heterozygous for this (recessive sterilizing) mutation had CNSs dissected (from 2-d-old pupae) and subjected to whole-mount anti-FRU^M histochemistry. A,B, Control brightfield micrographs (from PhotoShop assemblies of four to five consecutive focal-plane images each) obtained from a wild-type (WT) brain, representative of 20 specimens stained by peroxidase-mediated color reactions (Fig. 3, compareA, B). C,D, fru¹ anterior- and posterior-brain patterns, respectively, from scrutiny of 12 mutant specimens (processed and photographed as in A andB). Only a few cells with low-intensity staining were detected within the fru-aSP1 and fru-aSP2 clusters of fru¹ brains (asterisks, C vs A). C, The boxed area designates the absence of the normally stained fru-mAL cluster (cf. box in A). Certain neurons showed no apparent staining-intensity decrement compared with WT; this is exemplified by neurons pointed to byarrowheads in C (also seeE and F). Other FRU^M cells or clusters were absent or exhibited significantly decreased staining intensities in this mutant, e.g., in the vicinity of the mushroom-body calyx(D); these qualitative and quantitative anomalies of sex-specific fru expression are consistent with those obtained by in situ hybridizations using later-stagefru¹ pupae (Goodwin et al., 2000).E, F, Diagrams of representative anterior and posterior fru¹ brain views, respectively, showing cells or clusters with relatively strong staining intensities in brain regions that apparently correspond to those expressing FRU^M in WT. G,H, Confocal images showing, respectively, anterior views of 2-d-old male pupal brains from WT andfru¹ males (representative of 36 and 7 specimens, respectively, processed in this manner for animals of the two genotypes). Asterisks denote the location of the nearby fru-aSP1 and fru-aSP2 clusters that exhibit subnormal numbers and intensities of stained neurons infru¹(H). Brains from this mutant also contain FRU^M immunostaining in regions not labeled in WT. Such ectopic signals in fru¹ are widely distributed and show low-intensity staining.Arrowheads point to examples of such ectopic-expression regions. I, J, Confocal images showing ventral views of ventral nerve cords dissected from WT andfru¹ 2-d-old male pupae.K, Diagram of FRU^M-containing VNC neurons that gave relatively high-intensity staining. These cells are in posterior CNS regions that apparently correspond to the locations of such neuronal groups, although numbers of signal-containing cells are reduced within a given VNC region of the mutant. Scale bars, 100 μm.