Fig. 1.

Generation of transgenesis vector and establishment of G₀ transgenic animals. (A) Transgenesis vector consisting of a 1.6-kb fragment of MyHC1 promoter region upstream of the start codon and an mCherry reporter gene, flanked by inverted binding sites of meganuclease I-SceI. (B) Whole-mount in situ hybridization detecting MyHC1 expression in tentacle and retractor muscle cells in all eight mesenteries of a primary polyp. (C and D) Schematic cross-section through the body of a polyp at pharynx (p) position (C) and gastric position, as indicated in B. Endoderm is depicted in orange, ectoderm in blue, retractor muscles in red, and parietal muscles in purple. (E) mCherry reporter expression (red) in one mesentery of a primary polyp, reflecting a restricted transgenic patch. (F) mCherry reporter expression (red) in most mesenteries, demonstrating that large patches of transgenic tissue can be obtained in G₀. B, E, and F show a lateral view, with oral to the left. m, mesentery; P, pharynx opening; pm, parietal muscle; rm, retractor muscles; t, tentacle; tm, tentacle muscles. (Scale bar: 200 μm.)