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. Author manuscript; available in PMC: 2012 Mar 1.
Published in final edited form as: Dev Biol. 2010 Dec 11;351(1):186–198. doi: 10.1016/j.ydbio.2010.12.008

Figure 6. Neur also mediates asymmetric cell fate specification by activating Notch.

Figure 6

Embryos in panels A–H and S–U are stained with Eve; embryos in panels I-R are doubled stained with Eve and 22C10. Anterior is up, midline is marked by vertical lines. Larger arrow indicates anRP2, smaller arrow indicates a sib; smaller arrow with a star indicates mixed RP2-sib identity. Panel A: NotchTS mutant embryo showing two RP2s from the symmetrical division of GMC-1. Panel B: Notch; numb double mutant embryo with Notch phenotype epistatic to the numb phenotype. Panel C: numb embryo with both progeny of GMC-1 adopting a sib identity with a barely detectable Eve expression. Panels D–G: neur;numb double mutant embryos; many of the daughter cells of GMC-1 have mixed RP2-sib identity with reduced expression of Eve. Panel H: An older numb mutant embryo with a rarely seen phenotype of a smaller cell with weak Eve expression, as if this cell has a mixed RP2-sib identity. Panels I–I’: Two different focal planes (fp1 and fp2) of the same 10-hr old wild type embryo showing an RP2 with its projection (Panel I) and a sib with its weak 22C10 expression although no axon projection can be observed from it. Panel J: ~14 hour old wild type embryo with an RP2 with its projection; the sib cell has no Eve by this time and no 22C10 expressing cell is observed in the location where a sib normally resides. Panels K–O: numb mutant embryos. In Panels K and L, two examples of a larger cell with weak Eve and 22C10 expression are shown, in panel M, a smaller cell with weak Eve and 22C10 is shown. In panel N (younger 11-hr old embryo), a pair of cells, one larger than the other but both with weak Eve and 22C10 expression, is shown; the smaller cell is a normal sib. In panel O, an example of a larger cell with strong 22C10 expression is shown. These examples indicate a mixed identity for the cells of the RP2/sib lineage in numb mutants (see text). Panel P: A neur mutant embryo with strong Eve and 22C10 expression in the duplicated pairs of RP2 neurons. Panels Q and R: numb; neur double mutant embryos showing larger cells and smaller cells with weak Eve and 22C10 expression. Panels S–U: In panel S, duplication of the RP2 in insc mutants is shown; in panel T, hemisegments of a neur mutant embryo with both RP2s and sibs are shown. In panel U, neur; insc double mutant is shown with many more RP2s and no sibs, indicating that insc is epistatic to neur and enhances the neur symmetric division defect.