The distribution of sialic acids in nature

1. 1. The occurrence of sialic acids acids in nature has been studied. These acids are found in all species of Vertebrata, Cephalochorda, Hemichorda and Echinoderma tested. 2. 2. They are distributed sporadically in the phyla Platyhelminthes, Mollusca, Anthropoda and in bacteria. The acoel turbellarian, a primitive platyhelminth, contains sialic acid. In the mollusc and anthropod, sialic acid is found in a free state in the digestive glands of squid ( Loligo pealii ) and lobster ( Homarus americanus ). 3. 3. In the species tested there is no detectable sialic acid in flowering plants, ferns, mosses, lichens, algae, fungi, protozoa, slime mold and in species of the phyla Urochorda (tunicates), Prosopygia, Porifera, Ctenophora, Coelentera, Annelida, Sipuncoloidea, Nemertea and Chaetognatha. 4. 4. There appear to be several, new undescribed forms of sialic acid in the invertebrates, most of which contain glycolyl groups. 5. 5. The biosynthesis of sialic acid and the formation of cytidine-5′-monophospho-sialic acid have been investigated in some invertebrates.