Larval da dendrite screen – examples of phenotypes. (a) In a control third instar larva (GAL4109(2)80, UAS-mCD8::GFP/+), one can visualize the eight multidendritic neuron cell bodies of the dorsal cluster and the fields occupied by da neuron dendrites. Dotted boxes indicate fields examined at higher power in (c,e,g) to illustrate regions occupied primarily by the dendrites of class IV (c) (ddaC), class I (e) (ddaE), and class III (g) (ddaA) da neurons. (b) Misexpression of GSd302: severe reduction of higher order branches in class III and class IV da neurons, though the growth of primary branches of these and other da neurons appears intact. (c) Region in control highlighting (in red) the higher order branches of the class IV ddaC neuron. (d) Misexpression of GSd239 reduced the length of higher order branches of ddaC, with no obvious reduction in branch number. (e) Control ddaE (arrowhead at cell body), a class I da neuron that ordinarily has a simple pattern of lower order dendrite branches (highlighted in red). (f) Misexpression of GSd458 caused numerous small branches to emerge from ddaE (arrowhead at cell body). (h) Compared to controls (as in (g)), misexpression of GSd236 severely reduced numbers of spine-like protrusions in the class III neuron ddaA (cell body marked with arrowhead, dendrites highlighted in red). (i-k) Misexpression GSd402 and GSd450 caused severe reduction of dendrite outgrowth and branching (i,k), often with fewer GFP-labelled da neurons and signs of neuronal degeneration (higher power in (j,l)). All images are maximal Z-projections of stacked confocal images. Anterior is left and ventral is down. Scale bar in (a) = 100 μm and applies to (b) also. Scale bar in (c) = 30 μm and applies to (d-h) also. Scale bar in (i) = 100 μm and applies to (k) also.