Figure 7. miR-7 stabilizes gene expression and SOP determination under temperature fluctuation.

(A–B′) Ato protein (purple) in wildtype (A,A′), and miR-7^Δ1/Df(2R)exu1 mutant (B,B′) eye discs from animals grown under uniform temperature conditions. (A,B) show maximal projections of confocal z stacks. (A′,B′) show single focal planes.

(C–D′) Ato (purple) and Yan (green) proteins in wildtype (C,C′) and miR-7^Δ1/Df(2R)exu1 mutant (D,D′) eye discs from animals grown under fluctuating temperature conditions. Images are maximal projections of confocal z stacks.

(E-E″) Ato (red) and Sens (green) proteins in wildtype antennal discs from animals grown under fluctuating temperature steps. Sens marks the SOPs while Ato marks the PNCs. Sensory organs are progressively more developed in each panel. (E) An arc of coeloconic sensilla SOPs co-expressing Sens and Ato is first evident (purple arrowheads), along with the nascent Johnston’s organ, marked JO. A ring of cells expressing Ato surrounds the initial arista SOPs (arrow). (E′) SOP numbers increase within each organ system, and expression of Ato in these cells is reduced. (E″) There appears new rows of SOPs that are enveloped by cells with upregulated Ato (box).

(F-F″) miR-7^Δ1/Df(2R)exu1 mutant antennal discs from animals grown under fluctuating temperature conditions. (F) The nascent Johnston’s organ (JO) appears normal, but the arc of coeloconic sensilla SOPs (purple arrowheads) is depleted at the top of the arc. Cells in the arista domain do not express a ring of Ato and do not form arista SOPs (arrow). (F′) Deficits in SOP cell number and spacing in the arista and coeloconic SOPs are further seen. (F″) In addition to reduced SOP numbers, there is little or no up-regulation of Ato in cells enveloping new SOPs (box).