Biochemical characteristics of collagens from marine invertebrates with special emphasis on Polychaeta and Vestimentifera from deep-sea hydrothermal vents

The amino acid compositions of the cuticular collagens of five polychaete species (Arenicola marina, Nereis diversicolor, Alvinella pompejana, Alvinella caudata, Paralvinella grasslei) were compared using the Matsamura method revised by Murray et al. (1982). These results show the biochemical diversity of their cuticular collagens. We did not find any correlation between the amino acid composition of the cuticular collagens and the taxonomic position of the species investigated. Furthermore, there is no correlation between this composition and the type of habitat of the animals. In contrast with the cuticular collagens, all the interstitial collagens from polychaete species cluster in the same expected area. Thus, together these data indicate that vent annelid collagens do not exhibit any original biochemical characteristics when compared to that of coastal species. The cuticular collagen of the vestimentiferan Riftia pachyptila cannot be separated from the whole annelid cuticular collagen area when the Matsamura analysis is done starting with the constituent chain amino acid composition. The same is true for the vestimentiferan interstitial collagen when the method is applied to the primary sequence of the α chain. These results are in favor of the close phylogenetical relationship between polychaete and vestimentiferan collagens hypothetised by Sicot et al. (1997a).