Multiple sequence alignments and phylogenetic trees from: Co-option of the limb patterning program in cephalopod eye development

Background

Across the Metazoa, similar genetic programs are found in the development of analogous, independently evolved, morphological features. The functional significance of this reuse and the underlying mechanisms of co-option remain unclear. Cephalopods have evolved a highly acute visual system with a cup shaped retina and a novel refractive lens in the anterior, important for a number of sophisticated behaviors including predation, mating and camouflage. Almost nothing is known about the molecular-genetics of lens development in the cephalopod.

Results

Here we identify the co-option of the canonical bilaterian limb pattering program during cephalopod lens development, a functionally unrelated structure. We show radial expression of transcription factors SP6-9/sp1, Dlx/dll, Pbx/exd, Meis/hth, and a Prdl homolog in the squid Doryteuthis pealeii, similar to expression required in Drosophila limb development. We assess the role of Wnt signaling in the cephalopod lens, a posit...