Essential fatty acid deficiency and evidence for arachidonate synthesis in the cat

Sinclair, Andrew J.; Slattery, William J.; McLean, J. G.; Monger, E. A.

doi:10.1079/bjn19810012

Cited by 30 publications

(16 citation statements)

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“…Although the genome sequence is incomplete, we found partial Fads1 and Fads4 sequences in the cat genome, but no orthologues of Fads2 or Fads3 (L Filipe C Castro, unpublished). These findings are consistent with previous biochemical characterizations, in particular, the apparent absence of Δ6 activity in comparison to presence of Δ5 activity in domestic cat ( Felix catus ) [23], [24]. In the tetrapod clade, we demonstrated that a large and unique independent expansion of the Fads1 lineage in chicken (three genes) and green anole (five genes) has taken place but, at present, with no clues on possible functional impacts (Figure 5).…”

Section: Discussionsupporting

confidence: 92%

Functional Desaturase Fads1 (Δ5) and Fads2 (Δ6) Orthologues Evolved before the Origin of Jawed Vertebrates

et al. 2012

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Long-chain polyunsaturated fatty acids (LC-PUFAs) such as arachidonic (ARA), eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids are essential components of biomembranes, particularly in neural tissues. Endogenous synthesis of ARA, EPA and DHA occurs from precursor dietary essential fatty acids such as linoleic and α-linolenic acid through elongation and Δ5 and Δ6 desaturations. With respect to desaturation activities some noteworthy differences have been noted in vertebrate classes. In mammals, the Δ5 activity is allocated to the Fads1 gene, while Fads2 is a Δ6 desaturase. In contrast, teleosts show distinct combinations of desaturase activities (e.g. bifunctional or separate Δ5 and Δ6 desaturases) apparently allocated to Fads2-type genes. To determine the timing of Fads1-Δ5 and Fads2-Δ6 evolution in vertebrates we used a combination of comparative and functional genomics with the analysis of key phylogenetic species. Our data show that Fads1 and Fads2 genes with Δ5 and Δ6 activities respectively, evolved before gnathostome radiation, since the catshark Scyliorhinus canicula has functional orthologues of both gene families. Consequently, the loss of Fads1 in teleosts is a secondary episode, while the existence of Δ5 activities in the same group most likely occurred through independent mutations into Fads2 type genes. Unexpectedly, we also establish that events of Fads1 gene expansion have taken place in birds and reptiles. Finally, a fourth Fads gene (Fads4) was found with an exclusive occurrence in mammalian genomes. Our findings enlighten the history of a crucially important gene family in vertebrate fatty acid metabolism and physiology and provide an explanation of how observed lineage-specific gene duplications, losses and diversifications might be linked to habitat-specific food web structures in different environments and over geological timescales.

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Section: Discussionsupporting

confidence: 92%

Functional Desaturase Fads1 (Δ5) and Fads2 (Δ6) Orthologues Evolved before the Origin of Jawed Vertebrates

et al. 2012

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“…Thus, 18:2(n-6) would be elongated to 20:2(n-6) and then desaturated at the A8 position to yield 20:3(n-6), whilst 18:3(n-3) would proceed in a similar fashion via 20:3(n-3) to 20:4(n-3). In cats, which are frequently considered as being incapable of converting 18:2(n-6) to 20:4(n-6) (Rivers et al 1975;Hassam et al 1977), it has been proposed that a limited conversion can actually occur via A8 and A5 desaturases acting sequentially (Sinclair et al 1981). The predatory nature of the pike makes it an aquatic counterpart of the cat and similarities in PUFA metabolism may occur.…”

Section: Incorporation Of Radiolabelled Pufamentioning

confidence: 99%

The desaturation and elongation of 14C-labelled polyunsaturated fatty acids by pike (Esox lucius L.) in vivo

Henderson

Park

Sargent

1995

Fish Physiol Biochem

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To examine the ability of pike (Esox lucius L.) to modify exogenous PUFA by desaturation and elongation, (14)C-labelled 18:2(n-6), 18:3(n-3), 20:4(n-6) and 20:5(n-3) were injected intraperitoneally and the distribution of radioactivity in tissue lipid classes and liver PUFA measured. In all tissues examined, radioactivity from all (14)C-PUFA was recovered in many classes of acyl lipids and the level of recovery generally reflected the relative abundance of the lipid classes. Triacylglycerols, CGP and EGP usually contained high levels of all incorporated (14)C-PUFA. PI contained higher levels of radioactivity from (14)C-20:4(n-6) than from other injected substrates. In liver lipid, the Δ6 desaturation products of (14)C-18:2(n-6) and (14)C-18:3(n-3) contained no measurable radioactivity although the elongation products of the Δ6 desaturation products were labelled, as were the direct elongation products of these injected substrates. No radioactivity from (14)C-18:2(n-6) or (14)C-18:3(n-3) was detected in C20 or C22 products of Δ5 and Δ4 desaturation. Almost all radioactivity from injected (14)C-20:4(n-6) was recovered in this PUFA. Of the total radioactivity from (14)C-20:5(n-3) incorporated into liver lipid, 7% was present as 24:5 and 16.4% was recovered in hexaenoic fatty acids. In liver, 24:5(n-3) and 24:6(n-3) each accounted for 1% of the mass of total fatty acids and were located almost exclusively in triacylglycerols. The presence of radioactivity in these C24 PUFA suggests that in pike the synthesis of 22:6(n-3) from 20:5(n-3) may proceed without Δ4 desaturase via the pathway which involves chain shortening of 24:6(n-3). It is concluded that under the circumstances employed in this study pike, do not exhibit Δ5 desaturase activity and are unable to synthesize 20:4(n-6) and 20:5(n-3) from 18:2(n-6) and 18:3(n-3), respectively. This suggests that pike may require 20:4(n-6) and 20:5(n-3) preformed in the diet.

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“…By contrast, diets containing 50g safflower oil plus 300 g hydrogenated beef tallow (6.7 % energy as linoleate)/kg prevented all clinical symptoms except reproduction problems in females (MacDonald et al 1983b). Workers in Australia (Sinclair et al 1979(Sinclair et al , 1981McLean & Monger, 1989) reported that cats maintained for up to 8 years on diets containing 50g safflower oilkg did not suffer the severe symptoms reported by Rivers and his colleagues (Rivers & Frankel, 1980). These cats appeared normal except for some dulling of hair coats and a general inability of females to produce more than two litters.…”

Section: Essential Fatty Acids In Cats: Lack Of A-6 Desaturationmentioning

confidence: 99%

“…The existence of a A-8 desaturase (Fig. 3), although suggested as an alternative pathway for the formation of A 8,11,14-20:3 and AA (Sinclair et al 1981) has not been established. If it were present in cats to any considerable degree, AA synthesis from LA might occur by this alternative pathway.…”

Section: A-8 Desaturase Enzymesmentioning

confidence: 99%

“…Because A-6 desaturation appeared limited in cats, when diets rich in LA were fed an alternative chain elongation was observed, resulting in the modest accumulation of 20:2n-6 and the appearance of the novel fatty acid, A 5,11,14-20:3. This latter fatty acid was most probably the result of A-5 desaturation of 20:2n-6 produced via chain elongation of accumulated dietary LA (18:2n-6;Sinclair et al 1981;MacDonald et al 19846; Fig. 3).…”

Section: A-8 Desaturase Enzymesmentioning

confidence: 99%

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Fatty acid metabolism in domestic cats (Felis catus) and cheetahs (Acinonyx jubatas)

Bauer

1997

Proc. Nutr. Soc.

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The obligatory carnivorous nature of cats probably emerged as part of the slow adaptational process of these animals in becoming efficient predators rather than the result of a specific dietary requirement. Loss of the ability to produce needed nutrients from plant precursors was peripheral to this evolutionary change, but a lasting effect of it. As a result, present-day cats must meet their nutritional needs in the context of specialized requirements for dietary fat and other nutrients. These needs are most readily met by consumption of other mammalian tissues. High dietary concentrations of protein and special requirements for arginine, taurine, and retinol uniquely characterize feline nutrition. Like other mammals, cats cannot synthesize the essential fatty acid (EFA), linoleic acid (18:2n-6; LA). However, unlike other mammals, cats also have a limited capacity to synthesize arachidonic acid (20:n-6; AA) from LA and, similarly, eicosapentaenoic acid (20%-3; EPA) and docosahexaenoic acid (22:6n-3; DHA) from or-linolenic acid (1 8:3n-3; ALA). These features of fatty acid metabolism underscore the reliance of cats on other mammals to make these important fatty acids for them.The provision of the dietary EFA to domestic cats (Felis catus) is of interest to veterinarians and animal nutritionists, especially in view of their domestication and role as exclusive household companions. Among other members of the Felidae family, comparative differences are also of interest, not only because optimal nutritional care of captive zoological species must be provided, but also because reproductive performance depends on adequacy of the EFA. The importance of this latter concept with respect to endangered species such as the cheetah (Acinonyx jubutus) needs little added emphasis. Although most studies of feline fatty acid metabolism have been conducted in Felis catus, opportunities to investigate this topic in other species, when presented, have furthered our understanding of the unique lipid metabolic pathways of the order Carnivora. Results of recent studies in cheetahs from our laboratory are the focus of the present discussion, along with a review of fatty acid metabolism in cats. ESSENTIAL FATTY ACID CHEMISTRYMammalian EFA are straight-chain polyunsaturated hydrocarbons with all their double bonds in the cis-configuration. A convenient shorthand notation is often used by indicating the number of C atoms in the acyl chain and the number and position of the double bonds ( Fig.

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Essential fatty acid deficiency and evidence for arachidonate synthesis in the cat

Abstract: It has been suggested that the cat is unable to convert dietary linoleic acid to arachidonic acid (Rivers et al. 1975;Hassam et al. 1977). Studies by Sinclair et al. (1979) demonstrated that the cat has a deficiency in the synthesis of

Cited by 30 publications

References 10 publications

Functional Desaturase Fads1 (Δ5) and Fads2 (Δ6) Orthologues Evolved before the Origin of Jawed Vertebrates

Functional Desaturase Fads1 (Δ5) and Fads2 (Δ6) Orthologues Evolved before the Origin of Jawed Vertebrates

The desaturation and elongation of 14C-labelled polyunsaturated fatty acids by pike (Esox lucius L.) in vivo

Fatty acid metabolism in domestic cats (Felis catus) and cheetahs (Acinonyx jubatas)

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