The inability of the lion, Panthera leo L. To desaturate linoleic acid

Fatty acid metabolism in marine fish: Low activity of fatty acyl Δ5 desaturation in gilthead sea bream (Sparus aurata) cells

“…Deficiencies in fatty acyl desaturase activities have precedents in terrestrial carnivores such as cats in which Δ6 and Δ5 desaturase activities may both be very low (35)(36)(37)(38). It has been hypothesized that this situation may be an evolutionary adaptation to carnivorous diets rich in preformed C 20 and C 22 HUFA.…”

“…This is now also known to be the case in cats. In early studies, a complete lack of Δ6 desaturation enzymatic activity in felines was originally reported in the literature (35)(36)(37)(38), although recent and more sensitive studies conducted with deuterated fatty acids, showed that a low level of Δ6 desaturase is present in the cat (39).…”

Zebrafish cDNA Encoding Multifunctional Fatty Acid Elongase Involved in Production of Eicosapentaenoic (20:5n-3) and Docosahexaenoic (22:6n-3) Acids

“…In herbivores, whose diet is essentially deficient in HUFA, requirements for HUFA must be met by endogenous biosynthesis via desaturation and elongation of the copious C 18 PUFA in their plant diet. Carnivores, however, are generally dependent on a dietary supply of HUFA, which may be a response to a diet rich in HUFA but relatively poor in C 18 PUFA (Rivers et al, 1975(Rivers et al, , 1976. This spectrum of HUFA biosynthesis ability may be reflected in, and possibly caused by, genetic variation in structure and function of genes encoding the key enzymes in the HUFA biosynthesis pathway.…”

Low C18 to C20 fatty acid elongase activity and limited conversion of stearidonic acid, 18:4(n–3), to eicosapentaenoic acid, 20:5(n–3), in a cell line from the turbot, Scophthalmus maximus

“…In addition, results from in vivo studies with other marine fish species such as gilthead sea bream (Sparus aurata) and golden grey mullet (Liza aurata) were consistent with a deficiency in Δ5 desaturation [16,17]. Reduced flux through desaturase/elongase pathways due to reduced desaturase activities have precedents in terrestrial carnivores such as cats in which Δ6 and Δ5 desaturase activities may both be severely limited [18][19][20][21]. It was hypothesised that this situation may be an evolutionary response to differences in diet.…”

“…The results obtained for each enzymatic process when incubating the cells with the fatty acid which is the direct substrate (i.e. 18:4n-3 for C [18][19][20] elongase and 20:4n-3 for Δ5 desaturase) are of particular interest as they are an indication of the potential activity of each enzyme independent of the effects of enzymes preceding it in the pathway. Table 7 shows C 18-20 elongase products are always lower in TF cells than in AS cells for both n-6 and n-3 substrates, and this is particularly evident with the direct substrate, 18:4n-3, both radioactive (26% in TF and 81% in AS) and deuterated (10% in TF and 19% in AS).…”