ИСТИНА

Colonial hydrozoans at the polyp stage form highly elaborated colonies with a variety of branching patterns that makes them ideal models for studying the mechanisms of body plan diversification. Although patterning in hydrozoan polyps has been well studied, little is known about the patterning of architecturally complex hydrozoan colonies. In order to investigate the role of Wnt signaling in the patterning of the complex hydrozoan colonies we used non-model thecate hydrozoan, Dynamena pumila. Investigation of spatiotemporal expression patterns of Wnt ligands and endogenous Wnt signaling inhibitors during Dynamena colony development revealed that Wnt signaling involved not only in single-polyp-level but also in colony-level patterning. Using a functional approach, we have shown that pharmacological hyperactivation of the canonical Wnt pathway abolishes the formation of colony shoots, but not stolons in a young Dynamena colony. This leads to the development of a stolonal colony characteristic for other hydrozoan species (for example, Clytia hemisphaerica). Inhibition of the Wnt pathway arrests the formation of shoots as well as stolons, but the subsequent restoration of Wnt signaling leads to the transdifferentiation of shoots into stolons. Our findings demonstrate that specification of all structures (i.e. hydrants, shoots, and stolons) depends on the Wnt signaling activity in a dose-dependent manner and suggest the idea that fine-tuning of the canonical Wnt signaling could be one of the leading factors in the evolution of the spatial organization of hydrozoan colony. This work is funded by RFBR, grant ? 20-04-00978A