Figure 2

Expression of Oc-Ubx and Oc-abd-A in Orchesella embryos. Bright field images of NBT/BCIP stained (A, B, E, F) and confocal images of Fast Red stained (C, D, G) Orchesella embryos. (A-D) Oc-Ubx expression and (E-G) Oc-abd-A expression. (A and E) are ventral views, other pictures are lateral views, head at the top. Orchesella embryogenesis lasts 4.75 days; the embryos in (A, C, E) are 30 h, in (B, F) 32 h, and in (D, G) 48 h old. (A) The early signs of Oc-Ubx expression are seen as two pairs of dots (A1, A3), with a weak smudge in the middle (asterisk). (B) In an older embryo, the staining is more intense, extended laterally and slightly anteriorly. The staining does not spread behind A3. (C) Confocal image of an embryo aged as the embryo in (A). The intensity of staining obtained using this technique is stronger. In all (A-C) the expression is highest in A1. (D) In an older embryo with well-developed abdominal appendages, Oc-Ubx is detected in A1-A3. (E) The expression of Oc-abd-A appears as two pairs of dots (A3, A4). (F) In a slightly older embryo the staining is more intense and spreads one segment (black arrowhead) anteriorly. Staining in the dorsal organ (do) is not specific. (G) In an embryo with well-developed abdominal appendages, Oc-abd-A is detected in A2 to A4. A1 to A4, the first to the fourth abdominal segment; do, dorsal organ; h, head; T1 to T3, the first to the third thoracic segment. The interpretation of appendage identity is based on the observation of dozens of embryos; abdominal appendages can be distinguished by their specific morphology. Scale bars: all 100 μm.