Figure 2 legend:

The GAL4-UAS binary system of Drosophila melanogatser (Brand and Perrimon, 1991) allows cell lineages to be identified by expression of green fluorescent protein (GFP). With this system, cell-specific expression of the yeast GAL4 protein induces transcription of GFP when it binds to GAL4 binding sites (UAS, Upstream Activation Sequence) in the promoter region of the GFP gene. We have used the 201 Y-GAL4 line to label a subset of mushroom body neurons in culture (Yang et al., 1995) by expressing either GFP or n-syb-GFP (a fusion construct containing the neurons form of synaptobrevin and GFP, Estes et al., 1999).

Variability in response amplitudes from 201 Y-labeled mushroom body neurons. The amplitude of evoked Ca2+ increases were quantified in response to a 30s depolarizaions with either 30 or 60 mM K+ saline. Similar to data colleted from the entire population of neurons cultured from a single embryo (see results, Figure 4), the variable amplitudes were larger during 60 mM K+ stimulation. (Number of zones, cells, cultures), Soma-30K (20,13,9), 60K (19, 13,8): Growth Cone-30K (35,13,8), 60K (30,12,8).