Fig. 8. Mmy expression is temporally upregulated in developing epithelia and altered in mutants required for 20-hydroxyecdysone biosynthesis. (A-I) In situ hybridisation of wild-type embryos with mmy antisense probe. Embryos at early blastoderm stage display high levels of maternal mmy RNA (A), but no mmy transcript is detected in embryos between stages 5-10 (B; stage 8). Zygotic mmy expression is observed from stage 11 in tracheal cells as they invaginate from the ectoderm (C) and persists in the developing tracheal system until stage 15 (D,E,G) after which it decreases. At stage 16 mmy is strongly expressed in the salivary glands (F,H) and weakly detected in the epidermis (F,I). (J-O) In shade (shd) mutant embryos labelled with the mmy antisense probe, tracheal expression of mmy is not detected (J), instead mmy is prematurely expressed in the epidermis (J, black arrowhead; L,O), salivary gland (J,K; white arrowhead) and proventriculus (J,K; white arrow) during stage 15. A similar pattern of mmy expression is also found in mutants for shadow (sad; M and N). Scale bars: 50 µm in A-F,J,K,M,N; 25 µm in G; 10 µm in H; 25 µm in I,L,O.