title: Biosynthesis of eicosapentaenoic acid in the sea urchin Psammechinus miliaris.
abstract: The sea urchin Psammechinus miliaris (Gmelin) (Echinodermata: Echinoidea) was shown by using a deuterated tracer (D5-18:3n-3) and quantitation by negative chemical ionization gas chromatography-mass spectrometry to convert 18:3n-3 to 20:5n-3. The rate of conversion was very slow, corresponding to 0.09 microg/g tissue/mg 18:3n-3 eaten over 14 d. Deuterated arachidonic acid (D8-20:4n-6) was also included in the diet to give a measure of the relative amounts of diet eaten by the different animals. The recovery of this fatty acid in tissue lipids was 33.7% compared with only 0.95% recovery of D5-18:3n-3 and its anabolites, indicating that the majority of the D5-tracer was catabolized. Considerable elongation of D5-18:3n-3 into 20:3n-3 and a trace of 22:3n-3 was found, and these were accompanied by minor amounts of the intermediates 18:4n-3 and 20:4n-3. No deuterated 22:6n-3 was found.
authors.affiliation: Institute of Aquaculture, University of Stirling, Scotland, United Kingdom. m.v.bell@stirling.ac.uk
authors.forename: M V
authors.initials: MV
authors.lastname: Bell
authors.forename: J R
authors.initials: JR
authors.lastname: Dick
authors.forename: M S
authors.initials: MS
authors.lastname: Kelly
mesh_terms: D000818:Animals; D003903:Deuterium; D015118:Eicosapentaenoic Acid / Q000096:biosynthesis*; D044943:Fatty Acid Desaturases / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism; D008401:Gas Chromatography-Mass Spectrometry; D012617:Sea Urchins / Q000378:metabolism*
chemical_list: D005227:Fatty Acids; D015118:Eicosapentaenoic Acid; D003903:Deuterium; D044943:Fatty Acid Desaturases