Sequential Generation of Three Distinct Types of MB Neurons with Characteristic Axonal Projections

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(A-C) Axonal projections of marked MB neurons are revealed by the GFP fluorescence (green) and the MB lobes are immuno-stained by anti-FasII Ab (red). Inducing mitotic recombination in early larval life results in all GFP-positive axons, derived from isolated MB neurons, projecting into the g lobe (A). Inducing mitotic recombination in late larval life results in the GFP-positive axons projecting into the FasII-negative a'/b' lobes (B). Inducing mitotic recombination after PF results in GFP-positive axons projecting into the a/b lobes (C).

(D) Newly hatched larvae were collected, heat shocked to induce mitotic recombination at various times indicated on the X-axis, and were allowed to resume development at 25šC before the dissection performed within 5 days after eclosion. For a given time point, 20 brain lobes containing multiple two-cell/single-cell MB clones were examined for the axonal projection patterns of marked MB neurons (A-C). The percentage of brain lobes containing g, a'/b', and a/b neurons is shown in red, green, and blue, respectively, on the Y-axis. Note the ordered generation of morphologically distinct MB neurons. Two sharp transitions occurred at 3 days ALH and around PF. At the transition points, a significant portion of brain lobes contain both types of neurons, which explains why the total percentage of brain lobes containing a certain class of neurons is more than 100%. Genotype: hs-FLP/Y ; FRTG13,tubP-GAL80/FRTG13,UAS-mCD8-GFP ; GAL4-OK107/+.

Flybrain    Development   Sequential Generation    Figure 4

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