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dc.contributor.authorTocher, Douglas Ren_UK
dc.contributor.authorAgaba, Morris Ken_UK
dc.contributor.authorHastings, Nicolaen_UK
dc.contributor.authorTeale, Alan Jen_UK
dc.contributor.editorBrowman, H Ien_UK
dc.contributor.editorSkiftesvik, A Ben_UK
dc.description.abstractFish have an absolute dietary requirement for certain polyunsaturated fatty acids (PUFA) termed “essential fatty acids” (EFA) that include members of both the n-6 and n-3 series typified by linoleic acid, 18:2n-6, and α-linolenic acid, 18:3n-3. However, the biologically active forms of EFA are generally the C20 and C22 metabolites of 18:2n-6 and 18:3n-3, viz. 20:4n-6, 20:5n-3 and 22:6n-3. Some fish species can convert C18 PUFA to the C20 and C22 PUFA through a series of alternating desaturation and chain elongation reactions mediated by microsomal systems containing elongases and Δ6 and Δ5 fatty acid desaturases. In species that cannot perform these conversions, the C20 and C22 PUFA themselves are dietary EFA and their C18 homologues do not satisfy EFA requirements. The extent to which the foregoing statements apply quantitatively to a given fish species varies widely. Therefore, a vital area in lipid nutrition in fish is the provision of sufficient amounts of the correct EFA to satisfy the requirements for normal growth and development, requirements that can vary quantitatively during the life of the fish and are particularly important factors in larval marine fish. This paper reviews the work on defining and characterising the fatty acid desaturation and elongation pathway in fish. Biochemical studies have been advanced by the use of cell cultures which have elucidated key parts of the pathway. Thus, the presence of the so-called Sprecher shunt, where 22:6n-3 is produced from 20:5n-3 through two successive elongations and a Δ6 desaturase followed by peroxisomal chain shortening, was demonstrated in trout. Similarly, the block in the pathway in marine and/or piscivorous fish could be due to either a deficiency of C18-20 elongase or Δ5 desaturase and this varies between different marine species. Recent work has focussed on the molecular biology of the pathway with the cloning of fatty acid desaturases and elongases from a variety of fish species. Zebrafish have been used as a model species and a unique desaturase possessing both Δ6 and Δ5 activity along with an elongase with very high C18-20 activity have been cloned and characterised. Understanding this pathway is of increased importance due to the current dependence of salmonid and marine fish aquaculture on fish oil, the supply of which is becoming increasingly limited and unsustainable, necessitating the use in fish feeds of sustainable plant oils, rich in C18 PUFA, but devoid of C20 and C22 PUFA.en_UK
dc.publisherInstitute of Marine Research (IMR) / Fishlarvae.comen_UK
dc.relationTocher DR, Agaba MK, Hastings N & Teale AJ (2003) Biochemical and molecular studies of the polyunsaturated fatty acid desaturation pathway in fish. In: Browman HI & Skiftesvik AB (eds.) The Big Fish Bang: Proceedings of the 26th Annual Larval Fish Conference. Bergen, Norwary: Institute of Marine Research (IMR) /, pp. 211-228.
dc.rightsThis is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original author and source are credited.; Biochemical and molecular studies of the fatty acid desaturation pathway in fish. Tocher, D.R., M. Agaba, N.Hastings and A.J. Teale. (2003). pp: 211-228, In: Browman, H.I. & A.B. Skiftesvik (Eds.). The Big Fish Bang. Proceedings of the 26th Annual Larval Fish Conference. Published by the Institute of Marine Research, Postboks 1870 Nordnes, Bergen, Norway, ISBN 82-7461-059-8. Copyright: © 2003 Tocher et al.en_UK
dc.subjectPolyunsaturated fatty acidsen_UK
dc.subjectCall cultureen_UK
dc.subjectMolecular biologyen_UK
dc.subjectFishes Feeding and feedsen_UK
dc.subjectFishes Nutrition Requirementsen_UK
dc.titleBiochemical and molecular studies of the polyunsaturated fatty acid desaturation pathway in fishen_UK
dc.typePart of book or chapter of booken_UK
dc.type.statusAM - Accepted Manuscripten_UK
dc.citation.btitleThe Big Fish Bang: Proceedings of the 26th Annual Larval Fish Conferenceen_UK
dc.publisher.addressBergen, Norwaryen_UK
dc.contributor.affiliationInstitute of Aquacultureen_UK
dc.contributor.affiliationUniversity of Stirlingen_UK
dc.contributor.affiliationUniversity of Stirlingen_UK
dc.contributor.affiliationUniversity of Stirlingen_UK
rioxxterms.typeBook chapteren_UK
local.rioxx.authorTocher, Douglas R|0000-0002-8603-9410en_UK
local.rioxx.authorAgaba, Morris K|en_UK
local.rioxx.authorHastings, Nicola|en_UK
local.rioxx.authorTeale, Alan J|en_UK
local.rioxx.projectInternal Project|University of Stirling|
local.rioxx.contributorBrowman, H I|en_UK
local.rioxx.contributorSkiftesvik, A B|en_UK
local.rioxx.filenameBergen Conf final.pdfen_UK
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