ИСТИНА

The embryonic induction (Spemann, Mangold, 1924) is a widespread phenomenon in the development of high metazoans. When the activity of an embryonic region possessing the inductive ability is indispensable for the normal development of the primary body plan as a whole, this region is termed ‘organizer’. One of the regions in an embryo, which often possesses organizer capacity is the blastopore lip. The blastopore-associated organizer is a complex signaling center maintaining the BMP and Wnt signaling gradients regulating the establishment of primary body axes (De Robertis, 2008). Cnidaria are often regarded to be the simplest organisms having true gastrulation. In the anthozoan cnidarian Nematostella vectensis, the cells in the blastopore region express organizer-specific genes related to both signaling pathways mentioned above (Kusserow, et al., 2005; Lee et al., 2006; Rentzsch et al., 2006; Saina et al., 2009). We discovered that the tissue of the blastopore lip — but not tissue from other parts of the Nematostella embryo — is able to act as an embryonic organizer and to induce the formation of a secondary body axis upon transplantation into the host embryo (Kraus et al., 2007). In this project we tried to understand the molecular machinery behind the organizer activity of the blastopore lip in Nematostella.

1) We have shown that morphological variability of the transplantation outcomes may reflect the asymmetric distribution of inductive capacities along the circumference of the Nematostella blastopore. 2) We found that the inductive capacity of the Nematostella blastopore lip changes in the course of gastrulation. 3) Our results suggest that before the mid-gastrula stage the aboral area of Nematostella embryo is highly responsive to the signals from the organizer. Later in development this area becomes much more restricted in its developmental capacities.