Figure 1.

Phyla distribution of animals whose immune-inducible genes have been analyzed by the SSH method. A major evolutionary divide occurs in the animal kingdom between the so-called radially symmetric animals, which includes the cnidarian Hydra, and the bilaterally symmetric animals, which includes Schmidtea. The phylogenetic position of these two model organisms that have been selected for investigations in the present work (indicated by red color) promotes comparative analysis that may help to reconstruct functions and evolution of genes involved in regeneration and immunity. Previously, Branchiostoma belcheri [23], Danio rerio [24], Platynereis dumerilii [19], Biomphalaria glabrata [20,21], Thermobia domestica [12], Tribolium castaneum [14], Eristalis tenax [13], Manduca sexta [17], and Galleria mellonella [15] have been analyzed by the SSH method.