The preferential mobilisation of C20 and C22 polyunsaturated fatty acids from the adipose tissue of the chick embryo: potential implications regarding the provision of essential fatty acids for neural development

A dietary supplement of calcium soaps of fatty acids enhances luteal function in sheep

The effect of a dietary supplement of calcium soaps of fatty acids on luteal steroidogenic activity was studied in sheep. Mature 3- to 5-year-old North Country Cheviot ewes were given either a pelleted control diet (C; grass, beet pulp, barley; no. = 15) providing daily, 29⋅8 g nitrogen and 13⋅7 MJ of metabolizable energy (ME) or the same diet with 5% (w/w) of the ingredients replaced with protected lipid (C + CaFA; calcium soaps of fatty acids, Megalac, Volac Etd; no. = 15) for 21 days. The latter diet provided daily 30⋅2 g nitrogen and 15⋅9 MJ ME. At the end of the feeding period the ewes were slaughtered and blood samples and ovaries were collected from individual animals. The numbers of large- (≤ 4 mm diameter) and small- to medium-sized (1 to 3 mm diameter) follicles were recorded and follicular fluids from both size groups were stored for later analyses following centrifugation. Each mature corpus luteum (CL) was isolated from its ovary and sliced to provide a pair of ca. 0⋅3 mm diameter sections. These sections (mean = 163 (s.e.12) mg) were cultured separately (4 h; 39°C; 5% CO2) in 3 ml Medium 199 in the absence or presence of 100 μIU LH. Dietary supplementation of calcium soaps of fatty acids increased progesterone concentrations in the plasma (P < 0⋅05) and follicular fluid (P < 0⋅01 and P < 0⋅05 for large and small to medium follicles, respectively); trigylcerides in plasma (P < 0⋅05); total cholesterol in plasma (P < 0⋅001) and follicular fluid (P < 0⋅001); HDL-cholesterol in plasma (P < 0⋅001) and follicular fluid (P < 0⋅01) and LDL-cholesterol in plasma (P < 0⋅01). Progesterone released by luteal tissue into the culture medium in vitro from ewes given protected lipid was higher than that from tissue of control ewes (P < 0⋅05) and supplementary LH in vitro stimulated progesterone secretion by luteal tissues from both groups (P < 0⋅05). In conclusion, a dietary supplement of calcium soaps of fatty acids altered the intra-follicular environment surrounding the oocyte and follicular cells and enhanced luteal function in sheep.

Lipid metabolism in the embryos of diabetic rats during early organogenesis: modulatory effect of prostaglandin E2

The purpose of this work was to evaluate de novo lipid biosynthesis and the lipid profile, and to study the effect of prostaglandin E2 (PGE2; prostaglandin has previously been found to be involved in diabetes embryopathy) on lipid metabolism in embryos from control and streptozotocin-induced diabetic rats during organogenesis. Increased levels of triacylglycerols were found in embryos of diabetic rats compared with controls, whereas no differences were detected in the levels of cholesterol, cholesterylester, phosphatidylcholine and phosphatidylethanolamine. When the de novo synthesis of lipids in the embryo was studied using [14C]acetate as a tracer, a diminished rate of incorporation of [14C]acetate into the evaluated lipid classes was detected in the diabetic embryo compared with controls. Addition of PGE2 did not modify the incorporation of [14C]acetate into any of the lipid species of control embryos, but enhanced the incorporation of [14C]acetate into triacylglycerol, cholesterylesters, phosphatidylcholine and phosphatidylethanolamine of embryos from diabetic rats. The study's results show alterations in both synthesis and concentrations of lipids in the embryos of diabetic rats. Interestingly, the results demonstrate that the addition of PGE2, a prostaglandin that reverses the embryonic morphological abnormalities induced by diabetes, prevents disturbances in embryo lipid synthesis caused by diabetes.

Differential incorporation of docosahexaenoic and arachidonic acids by the yolk sac membrane of the avian embryo

During avian development, lipoproteins derived from yolk lipid are assembled in the yolk sac membrane (YSM) for secretion into the embryonic circulation. To investigate how yolk polyunsaturated fatty acids, essential for the development of certain tissues, are distributed among the lipid classes of the lipoproteins, pieces of YSM were incubated in vitro with [14C]arachidonic and [14C]docosahexaenoic acids (DHA). There was a marked difference in the partitioning of these two precursors among the lipid classes of the tissue. Of the radioactivity incorporated into total lipid from [14C]-arachidonic acid during 1 h of incubation, 67.3% was esterified as phospholipid and 29.5% as triacylglycerol. In contrast, only 14.6% of the label incorporated from [14C]-DHA was esterified as phospholipid, whereas 73.2% was recovered in triacylglycerol. This pattern of differential partitioning was observed at all time points and across a 20-fold range of fatty acid concentrations. There was no evidence for conversion of the radioactive arachidonic and DHAs to other fatty acids prior to incorporation into tissue lipids. It is suggested that the selective incorporation of yolk-derived DHA into the triacylglycerol of secreted lipoproteins represents part of a mechanism for directing this polyunsaturate to particular embryonic tissues.

Effect of estrogen and 2,3,7,8-tetrachlorodibenzo-rho-dioxin (TCDD) on plasma fatty acids of immature male chickens (Gallus domesticus)

This study investigated the effects of 2,3,7,8-tetrachlorodibenzo-rho-dioxin (TCDD) and estrogen on plasma lipids in immature male chickens. Fatty acids were quantified in plasma collected on day 14 from chickens injected with either: Estrogen plus TCDD-1 mg estradiol cypionate /kg body wt. daily for 3 days and 50 microg TCDD/kg body wt. on day 4; Estrogen--1 mg estradiol cypionate/kg body wt. daily for 3 days and vehicle only on day 4; TCDD-vehicle only for 3 days and 50 microg TCDD/kg body wt. on day 4; or Vehicle--same volume of appropriate vehicle for 4 days. TCDD treatment alone increased the plasma concentrations of total triacylglycerides and of the specific fatty acids 14:0, 15:0, 18:0, 18:2n6, 18:3n3, 20:0, 20:1n9, 20:2n6, 20:3n6, 20:5n3 and 22:1n9, compared with vehicle treatment. The concentration of 22:6n3 was increased in all plasma lipid classes of the estrogen group compared with the vehicle group, but was not increased in the estrogen plus TCDD group. Overall, TCDD treatment alone increased plasma lipids, possibly as a result of decreased clearance or utilization; whereas estrogen plus TCDD treatment antagonized estrogen-induced increases in 22:6n3 but did not cause hyperlipidemia.

Long-chain polyunsaturated fatty acids in rat maternal milk, offspring brain and peripheral tissues in essential fatty acid deficiency

Fatty acid status in humans is usually related to plasma or red blood cell fatty acid profiles. The aim of the study was to explore whether a maternal deficiency in dietary essential fatty acids would differentially affect lipid fractions in several tissues of the offspring, including brain. Female Wistar rats were fed an essential fatty acid-deficient diet during 3 months before mating. The fatty acid composition of different lipid fractions was examined in maternal milk, and in plasma, red blood cells, liver, adipose tissue, cerebral cortex and hippocampus of the offspring using thin layer and capillary column gas chromatography. Lipid fractions from most tissues of deprived offspring showed a common fatty acid profile characterized by elevated 20:3 omega9/20:4 omega6 ratio, and decreased docosahexaenoic acid and arachidonic acid. However, arachidonic acid was not affected in brain, even though 22:5 omega6 was increased in phospholipids of cerebral cortex and hippocampus. The present results demonstrate different degrees of resistance to essential fatty acid deficiency in lipid fractions and tissues. This suggests a priority distribution of arachidonic acid to preferential areas and shows that blood phospholipid fatty acids do not exactly reflect brain phospholipid status.

Feeding tuna oil to the sow at different times during pregnancy has different effects on piglet long-chain polyunsaturated fatty acid composition at birth and subsequent growth

In an attempt to prevent decreases in piglet 20 : 4n-6 status at birth while increasing 22 : 6n-3 status, multiparous sows (eight per treatment) were allocated to one of three different treatments: a basal diet fed from day 63 of pregnancy to term; basal diet supplemented with tuna oil (17.5 g/kg) from day 63 to day 91 and then basal diet alone from day 92 to term; basal diet alone from day 63 to day 91 and then basal diet supplemented with tuna oil from day 92 to term. Tuna oil supplementation increased mainly 22 : 6n-3 intake. Supplementation with tuna oil between day 92 and term increased 22 : 6n-3 to a greater extent in all piglet tissues (brain, liver, retina and the remaining carcass) at birth than supplementation with tuna oil between days 63 and 91. However, while piglet 20 : 4n-6 decreased to a greater extent in liver and carcass when diets were supplemented with tuna oil between days 92 and term than between days 63 and 91, in the brain and retina, the reverse was true; 20 : 4n-6 was decreased to a greater extent between days 63 and 91 than between 92 and term. The effect of pregnancy nutrition on the growth of piglets until 7 d postweaning (35 d of age) was assessed after removing any residual effects of pregnancy treatment by cross-fostering some piglets at birth. Piglets, the diets of whose dams had been supplemented with tuna oil during pregnancy, grew faster during the first 35 d of life than the progeny of sows fed only the basal diet. Feeding tuna oil to sows at different times during pregnancy therefore did not prevent decreases in piglet 20 : 4n-6 status at birth, but did suggest that changes in piglet brain 20 : 4n-6 status between days 63 and 91 of pregnancy were not reversible by later nutrition. Supplementing the diet of the pregnant sow with tuna oil had beneficial effects on postnatal piglet growth.

Transfer of n-3 and n-6 polyunsaturated fatty acids from yolk to embryo during development of the king penguin

This study examines the transfer of lipids from the yolk to the embryo of the king penguin, a seabird with a high dietary intake of n-3 fatty acids. The concentrations of total lipid, triacylglycerol (TAG), and phospholipid (PL) in the yolk decreased by ~80% between days 33 and 55 of development, indicating intensive lipid transfer, whereas the concentration of cholesteryl ester (CE) increased threefold, possibly due to recycling. Total lipid concentration in plasma and liver of the embryo increased by twofold from day 40 to hatching due to the accumulation of CE. Yolk lipids contained high amounts of C(20-22) n-3 fatty acids with 22:6(n-3) forming 4 and 10% of the fatty acid mass in TAG and PL, respectively. Both TAG and PL of plasma and liver contained high proportions of 22:6(n-3) ( approximately 15% in plasma and >20% in liver at day 33); liver PL also contained a high proportion of 20:4(n-6) (14%). Thus both 22:6(n-3) and 20:4(n-6), which are, respectively, abundant and deficient in the yolk, undergo biomagnification during transfer to the embryo.

Lipids of the eggs and neonates of oviparous and viviparous lizards

The purpose of this article is to collate the compositional data for the lipids of the eggs and neonates of ten species of lizards displaying a range of parity modes, to highlight emergent trends and to identify some of the physiological changes central to the evolution of viviparity. The eggs of oviparous species and of viviparous species with a simple (type I) placenta are characterised by very high proportions of triacylglycerol which forms over 80% (wt. /wt.) of the total yolk lipid. The eggs of viviparous species with complex (types II and III) placentae contain lower proportions of triacylglycerol (about 70% of total yolk lipid) and commensurately greater proportions of phospholipid, cholesteryl ester and free cholesterol. The fatty acid compositions of the yolk lipids are very similar for all the lizard species, irrespective of parity mode; in particular, the proportions of docosahexaenoic acid are consistently low. For all the species, the proportions of both docosahexaenoic and arachidonic acids are higher in the phospholipid of the neonate compared with the egg. The difference between the lipid contents of the eggs and the neonates indicates that, in species of Pseudemoia which have a complex (type III) placenta, more than 50% of the total lipid supplied to the embryo is derived from placental transport.

Fatty acids and squalene carried by alpha fetoprotein, and fetal and adult serum albumin from chicken. Comparison with these from mammals

Alpha fetoprotein (C-AFP), serum albumin (C-fSA) from chicken embryos, and SA from hens were purified using gentle chromatographic and electrophoretic methods, and their fatty acids (FAs) and squalene contents were analyzed using gas chromatography and mass spectrometry. In 7-day-old chick embryo, AFP carries 16% and fSA 6% free FAs, the rest being carried as phospholipids, which differs from rat and pig AFP, where all fatty acids are carried like free fatty acids. At this stage C-AFP contains 3.6% arachidonic acid, which falls to 1.7% in 14-day-old embryos. Both of these figures are significantly lower than in humans, rats, calves, and pigs. C-AFP does not transport docosahexaenoic acid, in notable contrast to the mammals mentioned above. The finding of squalene in the two fetal proteins is reported for the first time. During the interval between 7 and 14 days, the proportion of C16:1 n-7 and of C18:2 n-6 increases 10-fold, that of C18:0 quadruples, and that of C18:1 n-9 decreases 3-fold. Squalene increases in this period from 2.2% to 10.0%. The C-fSA of a 7-day-old embryo transports only one FA with more than two unsaturated carbons, arachidonic acid (2.4%). It also contains squalene (1.2%). Similarly, only arachidonic acid (2.5%), but not squalene is found in hen SA. The percentage of saturated and monounsaturated FAs divided by the percentage of polyunsaturated FAs, and the ratios of the percentage of FAs with C14-C18 with respect to those with C20-C22 transported by C-AFP are very different from those of studied mammals.

Fatty acid composition of the adipose tissue and yolk lipids of a bird with a marine-based diet, the emperor penguin (Aptenodytes forsteri)

The emperor penguin (Aptenodytes forsteri) is an Antarctic seabird feeding mainly on fish and therefore has a high dietary intake of n-3 polyunsaturated fatty acids. The yolk is accumulated in the developing oocyte while the females are fasting, and a large proportion of the fatty acid components of the yolk lipids are derived by mobilization from the female's adipose tissue. The fatty acid composition of the total lipid of the yolk was characterized by high levels of n-3 polyunsaturated fatty acids. However, it differed in several respects from that of the maternal adipose tissue. For example, the proportions of 14:0, 16:1n-7, 20:1n-9, 22:1n-9, 20:5n-3, and 22:6n-3 were significantly greater in adipose tissue than in yolk. Thus adipose tissue lipids contained 7.6+/-0.3% and 8.0+/-0.3% (wt% of total fatty acids; mean +/- SE; n = 5) of 20:5n-3 and 22:6n-3, respectively, whereas the yolk total lipid contained 1.6+/-0.1 and 5.5+/-0.3% of these respective fatty acids. The proportions of 16:0, 18:0, 18:1n-9, 18:2n-6, and 20:4n-6 were significantly lower in the adipose tissue than in the yolk lipids. The proportions of triacylglycerol, phospholipid, free cholesterol, and cholesteryl ester in the yolk lipid were, respectively, 67.0+/-0.2, 25.4+/-0.3, 5.3+/-0.2, and 1.8+/-0.2% (wt% of total yolk lipid). The proportions of 20:4n-6, 20:5n-3, 22:5n-3, and 22:6n-3 were, respectively, 5.7+/-0.3, 2.8+/-0.2, 1.4+/-0.1, and 11.7+/-0.5% in phospholipid and 0.4+/-0.0, 1.2+/-0.1, 0.8+/-0.1 and 3.6+/-0.3% in triacylglycerol. About 95% of the total vitamin E in the yolks was in the form of alpha-tocopherol with gamma-tocopherol forming the remainder. Two species of carotenoids, one identified as lutein, were present.