Figure 4

Dynamics of Broad isoform expression during metamorphosis. (A) Z-projection of the ventral CNS showing the distribution of nuclei expressing Br-Z1, -Z3 and -Z4 at various times after puparium formation (APF). The neuropil staining for Br-Z1 at 94 h APF is likely due to a cross-reacting epitope rather than Broad. (B) Confocal sections showing Broad immunostaining in secondary neurons in the apical layers of the thoracic neuromeres at puparium formation. Br-Z4+ neurons are a subset of neurons that show Broad-core immunostaining. The Br-Z3+ neurons completely overlap the Broad-core immunostained neurons. The large nuclei of glia cells show no Br-Z3 and reduced Br-Z4 (arrows). (C) Cross-section in the T2 region of the CNS from a wandering stage larva that carried green fluorescent protein (GFP)-labeled MARCM clones and was immunostained for Br-Z4. Br-Z4+ cells were located at an intermediate layer of the cellular rind; the dotted line shows the outline of the CNS. (D, E) Comparison of immunostaining for Br-Z4 and Br-Z1 with that of Broad-core in the pharate adult nervous system. (D) Ventral view of the T1-T2 neuromeres showing that essentially all of the Broad-core+ neurons also show Br-Z4 immunostaining. By contrast, only a moderate number of Broad-core neurons also show the Br-Z1 epitope. (E) The brain shows a cluster of neurons that express BR-Z1 but not Br-Z4 (arrow) near the junction with the optic lobes (OL).