Figure 7.

Expression of two Wnt/β-catenin pathway genes during regeneration and fission. Whole mount in situ hybridizations of Pl-fzA (A-E) and Pl-β-cat (F-J) show that both genes are expressed in the developing regeneration blastema as well as in new tissues forming by fission. (A-D) Following anterior amputation, Pl-fzA expression is not detectable (or only faintly so) before a blastema forms (A: 12 hours post amputation (hpa)), begins to be expressed in the early blastema (B: 1 day post amputation (dpa)) and persists through mid-stages of regeneration (C: 2 dpa). Pl-fzA is expressed in a similar fashion during posterior regeneration (D: 2 dpa). (F-I) Following anterior amputation, Pl-β-cat is similarly not detectable (or only faintly so) prior to blastema formation (F: 12 hpa), begins to be expressed in the early blastema (G: 1 dpa), and persists through mid-stages of regeneration (H: 3 dpa). Pl-β-cat is also expressed during posterior regeneration (I: 2 dpa). (E, J) During fission, both genes are expressed in developing fission zones (E, J: early fission - stage B), the transverse regions of tissue from which a new head and tail form (see Figure 1). All panels are lateral views with anterior to the left. Dark gray bars mark the extent of new tissue, i.e., the regeneration blastema or fission zone. Arrows point to early phase of expression of each gene on day 1.