Fig. 2. Genetics of Ci155 accumulation. In A-E, clones of cells of the indicated mutant genotypes are identified by the absence of lacZ marker gene expression (magenta). The green channel shows Atonal protein in panel A and Ci155 for panels B-E. Absolute levels of Ci155 should not be compared between panels, as these preparations were recorded on widely different occasions. (A) Cells lacking smo fail to turn on atonal at the normal time anterior to the morphogenetic furrow (green; horizontal arrows). Lower Atonal levels that still suffice for R8 specification appear more posteriorly (vertical arrow). (B) Cells lacking smo fail to accumulate Ci155 ahead of the morphogenetic furrow (horizontal arrows). Ci155 does accumulate more posteriorly in the smo-mutant cells (vertical arrow), before disappearing as differentiation begins (e.g. asterix). (C) By contrast, Ci155 does not accumulate in cells mutant for both smo and tkv. (D) Ci155 does not accumulate in cells mutant for both smo and Mad. (E) There is a subtle but reproducible reduction in Ci155 levels in clones mutant for tkv, which is associated with little or no change in the pattern or timing of differentiation.