ИСТИНА

In cnidarians, canonical Wnt (cWnt) signaling patterns the primary body axis and controls oral identity during larval body plan formation. In many cnidarians, it also specifies a single region of gastrulation morphogenetic movements, so embryo morphology is coupled with axial molecular patterning throughout so-called polar gastrulation. But in numerous hydrozoan cnidarians, no morphological landmarks indicate an embryonic polarity during gastrulation. The question remains whether сWnt signaling controls morphogenetic processes involved in apolar gastrulation. We focused on the embryonic development of Dynamena pumila, the hydrozoan species with apolar gastrulation. We revealed that the first signs of morphological polarity appear only after the end of gastrulation. However, molecular prepatterning of the embryo does exist in the middle of gastrulation as in situ analyses of oral markers Wnt3, Axin and TCF demonstrated. We have shown experimentally that molecular axial patterning is highly robust in D. pumila. Our results suggest that morphogenetic processes are uncoupled from molecular axial polarity until the late gastrula stage in D. pumila. Investigation of D. pumila might significantly expand understanding, how morphogenetic cellular movements and axial molecular patterning are linked in Metazoa. The work is supported by RFBR, 20-04-00978a.