Figure 2

The DM NBs generate an exceptional number of neuronal progenitors. (a-d') Confocal images of representative non-DM and DM lineages labeled with mCD8::GFP (membrane marker, green) in larval brains stained for the markers indicated. Each panel shows the most superficial area of a single NB clone viewed around the NB (asterisk) in the dorsal brain. The GFP channel is omitted for clarity in the lower panels and green dots outline the clones. Note that (a', b') show close up views of the areas boxed in (a, b). Progenitor cells in an NB lineage include the NB identifiable by its size (asterisk) and the most recently born cells in its associated progeny. These cells are found in close spatial proximity to the NB and are characterized by a weak level of cortical Miranda (red in a-b') and the absence of the neuronal marker ELAV (blue in a-b'). (c-d') NB-associated cells are unambiguously defined as progenitors by the expression of the cell cycle markers Cyclin E and/or PH3. (e) Quantification of various markers in NB clones at 96 h ALH underscores the high number of small progenitor cells among the progeny of the DM NBs. (f) DM NBs are always associated with the highest number of non-NB progenitors during larval development. Cell counts were performed on three types of clones recorded on the same samples for comparisons: DM, dorsomedial NB clones; MB, mushroom body NB clones; others, clones chosen at random in dorsal areas of the brain and not belonging by position and morphology to the other groups. In each case, the average number of progenitors is plotted with an error bar representing standard deviation. The number of clones examined is indicated bellow. Scale bars: 10 μm.