Fig. 2.

Regulation of dmiR-1 in cardioblast and visceral muscle cells. (a) Map of the dmiR-1 locus showing the position of the 4.6-kb dmiR-1 enhancer (green) and subfragments, with expression domains summarized as follows: SM, somatic muscle; VM, visceral muscle; CB, cardioblast; PC, pericardial cell. An A/T-rich SRF-like-binding site conserved in other Drosophila species is highlighted. (b–m) GFP expression in embryos carrying the 4.6-kb (b–g), 2.5-kb (h and i), 0.72-kb (j and l), or SRF-like site-mutated 0.72-kb (k and m) element. Embryos were costained with anti-Dmef2 (c and i) or anti-Twist (e and g). (n) Luciferase (luc) activity determined with luciferase reporters linked to the 0.72-kb element or the SRF-like site mutated (CArGm) 0.72-kb element in Drosophila S2 cells in the presence or absence of Drosophila SRF and myocardin-related transcription factor. Error bars indicate standard deviations. (b, c, h–k) Dorsolateral views of stage 16 embryos. (d–g) Lateral views of stage 11 embryos. f and g are ×40 images of d and e, respectively. l and m are inside views of j and k embryos, respectively, focusing on visceral muscles. Arrowheads indicate the presence (b, h, and j) or absence (k) of the heart tube, and arrows indicate somatic (b, h, k, and j) and visceral muscles (l).