Comparative study of XXXX chains released from the oviducal mucins of the two very closely related amphibian species @entity72505 and @entity69797 .

@entity1 @entity72506 @entity1735 @entity27055 @entity4826 @entity26243 @entity19447 @entity27054 @entity69797 @entity72505
The eggs of amphibians are surrounded by an extracellular matrix, termed jelly coat, which is mainly composed of hydrated mucin-type glycoproteins. These highly glycosylated molecules are synthesized by the oviduct and play an important role in the fertilization process. From a structural and chemical point of view, these oviducal mucins are very different from one species to another and they could be involved in the species-specificity of gamete interactions or could influence the parasite tropism. @entity72505 and @entity69797 are the two most closely related species within the genus, which hybridize readily in nature. Divergence occurred during geographic isolation estimated at 2-7 million years ago. The oviducal mucins of these species have been studied at the @entity1735 level, and the primary structures of 28 compounds have been established by NMR spectroscopy. The @entity1735 chains released from the oviducal mucins of the two species were similar and characterized by the common sequences @entity4826 (beta 1-3)[Fuc(alpha 1-4)]GlcNAc(beta 1-6) and @entity4826 (alpha 1-4)Gal(beta 1-4)Gal(beta 1-3) attached to @entity26243 -ol (core 2). Nevertheless, some differences confirmed the strict species-specificity of amphibian oviducal @entity1735 chains observed previously. On the one hand, the presence of beta Gal 1,4-linked to beta @entity4826 in @entity72505 , but not in @entity69797 , can indicate that beta 4GalT: beta @entity4826 and beta 4GalT: beta @entity19447 are two distinct glycosyltransferases. On the other hand, @entity72506 (Kdn) is present in @entity72505 , and @entity27054 ( @entity27055 ) in @entity69797 . Although the enzymes involved in the biosynthesis of Kdn are not as well characterized, it can be suggested that at least one step of the biosynthetic pathway of NeuAc has been disrupted, leading the @entity72505 oviducal NeuAc-9-synthase to use @entity1 -6-P as a substrate, instead of ManNAc-6-P.
