title: Cloning and nutritional regulation of a Delta6-desaturase-like enzyme in the marine teleost gilthead seabream (Sparus aurata).
abstract: Marine fish are presumed to have a lower capacity than freshwater fish for the bioconvertion of 18C fatty acids into 20-22C highly unsaturated fatty acids (HUFA). The present work investigated the first step of this pathway, the Delta6-desaturation, in gilthead seabream. A full-length desaturase-like cDNA was identified from total RNA extracted from viscera of juvenile fish fed for 96 days on an experimental HUFA-free diet containing olive oil as the sole lipid source. The open reading frame encodes a 445-amino acid peptide that contains two membrane-spanning domains, three histidine-rich regions, and a cytochrome b(5) domain, which are characteristic of Delta6- and Delta5-desaturases. Predicted protein sequence of seabream desaturase-like indicated a high percentage of identity with mammalian Delta6-desaturases (approx. 65%). Northern analysis showed two transcripts of approximately 3.7 and 1.8 kb which were highly expressed in fish fed on HUFA-free diet and slightly expressed in fish fed on HUFA-rich diet. The fatty acid profile of the former group was characterized by high levels of Delta6-desaturation products (18:2 n-9 and 20:2 n-9) with no detectable levels of Delta5-desaturation product (20:3n-9). These results demonstrate for the first time the presence and nutritional modulation of a Delta6-desaturase-like cDNA in a marine fish.
authors.affiliation: Laboratory of Fish Nutrition, Unité mixte INRA-IFREMER, 64310, St-Pée-sur-Nivelle, France. seiliez@st-pee.inra.fr
authors.forename: I
authors.initials: I
authors.lastname: Seiliez
authors.forename: S
authors.initials: S
authors.lastname: Panserat
authors.forename: G
authors.initials: G
authors.lastname: Corraze
authors.forename: S
authors.initials: S
authors.lastname: Kaushik
authors.forename: P
authors.initials: P
authors.lastname: Bergot
mesh_terms: D000595:Amino Acid Sequence; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004032:Diet; D004041:Dietary Fats / Q000494:pharmacology; D005227:Fatty Acids / Q000032:analysis; D020869:Gene Expression Profiling; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D021541:Sea Bream / Q000235:genetics*; D017385:Sequence Homology; D013230:Stearoyl-CoA Desaturase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*
chemical_list: D004041:Dietary Fats; D005227:Fatty Acids; D012333:RNA, Messenger; D013230:Stearoyl-CoA Desaturase