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. Author manuscript; available in PMC: 2023 Aug 8.
Published in final edited form as: Dev Cell. 2022 Jul 13;57(15):1817–1832.e5. doi: 10.1016/j.devcel.2022.06.016

Figure 1. ss controls R7 subtype specification.

Figure 1.

A) R7 subtype specification. Expression of Ss promotes the Rh4-expressing R7 fate. Absence of Ss yields the Rh3-expressing R7 fate.

B) Wild-type retinas contain 33% Rh3/SsOFF R7s and 67% Rh4/SsON R7s in a random pattern (left). ss protein null mutants contain only Rh3/SsOFF R7s and no Rh4/SsON R7s (right). Scalebar=20 μm.

C) ss gene locus. Black oval=exon; black arrow=promoter; red rectangle=silencer; green rectangle=enhancer; S1=silencer 1; S2=silencer 2; EE=early enhancer; LE=late enhancer.

D) Schematized eye-antennal imaginal disc. Antenna is subdivided into the A1, A2, and A3/arista. A=anterior; P=posterior; MF=morphogenetic furrow.

E-H) Schematized depiction of R7 maturation. Insets illustrate how cells proceed through development over time. Gray=undifferentiated cells/U; green=precursors/P; blue=differentiating cells/D; orange=R7.