Fig. 2

In situ hybridization of spatial expression of GH6-1 in Ciona embryos. A The hybridization signal was not observed in gastrula stage (6 hpf). B The GH6-1 signal in epidermal cells is first observed at the tail-tip region of late neurulae (arrow; 8 hpf) followed by C early (arrow; 9 hpf) and D mid tailbud stages (arrow; 10 hpf). E, F Expanded signals of GH6-1 are evident in epidermal cells at (E) late tailbud I stage (12 hpf) and (F) late tailbud II stage (13.5 hpf). Panels Ea, Eb, and Ec show enlargement of the area shown in E. Ea The specimen viewed from anterior (left) and posterior side (right). White arrowheads show regions corresponding to adhesive papilla primordia; Eb viewed from the dorsal side, and Ec from the side. F Late tailbud stage (13.5 hpf). Arrows show a strong signal at tail-tip epidermis, while arrowheads show moderate signal along tail midline epidermis. G–L Control embryos treated with sense riboprobe show undetectable level of signal. G Gastrula; H late neurula; I early-to-mid tailbud; J mid tailbud; K late tailbud I; L late tailbud II. A–E, Ea, and F are at the same magnification as panel A, in which a scale bar represents 100 μm. Scale bars in Eb and Ec represent 100 μm. G Shows a scale bar of 100 μm; H–L Are at the same magnification as G. The d footnote in A, B, and Eb denotes a dorsal view