Collagen type IV in the Ctenophore Pleurobrachia bachei

Abstract

The evolution of multicellular animals required the development of epithelial tissues that function in controlling the transport of molecules from one environment to another. Collagen proteins are crucial to the formation of epithelial tissues, and are therefore critical in understanding the origins of multicellularity and Metazoa. We looked for collagen type IV proteins in the recently sequenced Ctenophore Pleurobrachia bachei genome, to assess whether this most basal of Metazoa phylum could contain conserved collagen proteins. We used Homo sapiens collagen type IV sequences and Blasted against the Moroz lab P.bachei genome server to search for collagen type IV proteins. We found that P. bachei possesses 6 distinct type IV alpha chains along three scaffolds, two of which were aligned in a head-to-head fashion, indicating both traditional and inverted gene duplication events. Given recent evidence suggesting that Ctenophores are possibly the most basal of the Metazoans, our findings suggest that the common ancestor to all Metazoa contained a much more developed collagen profile than previously appreciated.