[B-PT26] Geogenomics

[BPT26-P04] Molecular basis of shell formation and shell evolution in gastropods

*Keisuke SHIMIZU¹, Kazuyoshi ENDO², Tetsuhiro KUDOH³ (1.University of Kyoto, 2.The University of Tokyo, 3.University of Exeter)

Keywords:Shell evolution, RA pathway, Mollusca

The Molluscs constitutes one of the most diverse animal phyla, and they have evolved calcified exoskeletons called “shell” ever since the Cambrian. However, the molecular basis of molluscan shell development remains unclear. Thus we sought to understand the role of the homeotic gene engrailed in early shell development by focusing on retinoic acid signal pathway. We examined the expression patterns of RA metabolizing enzyme cyp26 in the limpet Nipponacmaea fuscoviridis and found that cyp26 is expressed around the edge of the shell field. As a result of gain or loss functional analysis of RA, shell deformation was observed in both gain and loss of RA analyses, and engrailed is down regulated. These results suggested that the common ancestor of Mollusca likely used RA signaling system to produce the novel phenotypic trait that is to be called “shell” by recruiting the homeotic gene.