Fig. 7
Comparison of “head” vs. “tail” gene expression in the regeneration of Nematostella and Planaria. A cartoon of the two animals is presented with the oral (head) part of Nematostella aligned with the posterior (tail) part of Planaria according to the comparison in which these ends express an assembly of Wnts and other universal bilaterian posterior markers, while the aboral part resembles the Planarian anterior (head) part in the expression of universal anterior markers such as Six3/6 and Wnt inhibitors like sFRPs [51]. Some of the markers specific for the main axis ends are depicted with Wnts and Wnt pathway genes in red and orange, FGF pathway members in brown, homeobox factors in light blue, forkhead (Fox) factors in purple, and other TFs in green. An anterior Planaria regeneration marker and protease, proprotein convertase 2 (PC2) and its ortholog in Nematostella, the late aboral Pep8 gene are marked in grey. Highlighted in light green are bona fide orthologs that are expressed as expected according to this comparison, while yellow marks polarized genes that are expressed in an ‘inverted’ position, which can indicate evolutionary change in the regeneration program. aThe FoxD1 gene is induced at the oral regenerating region in Nematostella however it is aboral in embryonic/larval development and becomes orally expressed upon metamorphosis and tentacle budding [95]. b Dickkopf (DKK) is expressed higher orally at 8 h after the induction of regeneration and higher in the aboral part later than 24 h. c Runt-1 is induced in anterior sites upon eye and neural brain regeneration in Planaria but is also expressed in posterior wound sites [35, 37] and https://radiant.wi.mit.edu/app/