Short-chain Saturated Fatty Acids Research Articles

Trace element and molecular markers of organic carbon dynamics along a shelf–basin continuum in sediments of the western Arctic Ocean

Molecular organic biomarkers together with trace element composition were investigated in sediments east of Barrow Canyon in the western Arctic Ocean to determine sources and recycling of organic carbon in a continuum from the shelf to the basin. Algal biomarkers (polyunsaturated and short-chain saturated fatty acids, 24-methylcholesta-5,24(28)-dien-3β-ol, dinosterol) highlight the substantial contribution of organic matter from water column and sea-ice primary productivity in shelf environments, while redox markers such as acid volatile sulfide (AVS), Mn, and Re indicate intense metabolism of this material leading to sediment anoxia. Shelf sediments also receive considerable inputs from terrestrial organic carbon, with biomarker composition suggesting the presence of multiple pools of terrestrial organic matter segregated by age/lability or hydrodynamic sorting. Sedimentary metabolism was not as intense in slope sediments as on the shelf; however, sufficient labile organic matter is present to create suboxic and anoxic conditions, at least intermittently, as organic matter is focused towards the slope. Basin sediments also showed evidence for episodic delivery of labile organic carbon inputs despite the strong physical controls of water depth and sea-ice cover. Principal components analysis of the lipid biomarker data was used to estimate fractions of preserved recalcitrant (of terrestrial origin) and labile (of marine origin) organic matter in the sediments, with ranges of 12–79%, 14–45%, and 37–66% found for the shelf, slope, and basin cores, respectively. On average, the relative preserved terrestrial organic matter in basin sediments was 56%, suggesting exchange of organic carbon between nearshore and basin environments in the western Arctic.

Assessment of dietary ratios of red clover and grass silages on milk production and milk quality in dairy cows

Twenty-four multiparous Holstein-Friesian dairy cows were used in a replicated 4×4 Latin square changeover design experiment to test the effects of changing from ryegrass (Lolium perenne) silage to red clover (Trifolium pratense) silage in graded proportions on feed intakes, milk production, milk organoleptic qualities, and whole-body nitrogen partitioning. Four dietary treatments, comprising ad libitum access to 1 of 4 forage mixtures plus a standard allowance of 4 kg/d dairy concentrates, were offered. The 4 forage mixtures were, on a dry matter (DM) basis: 1) 100% grass silage, 2) 66% grass silage: 34% red clover silage, 3) 34% grass silage: 66% red clover silage, and 4) 100% red clover silage. In each of 4 experimental periods, there were 21 d for adaptation to diets and 7 d for measurements. There was an increase in both DM intakes and milk yields as the proportion of red clover in the diet increased. However, the increase in milk yield was not as great as the increase in DM intake, so that the efficiency of milk production, in terms of yield (kg) of milk per kg of DM intake, decreased. The concentrations of protein, milk fat, and the shorter chain saturated fatty acids decreased, whereas C18 polyunsaturated fatty acids (PUFA) and long-chain PUFA (C20+) increased as the proportion of red clover in the diet increased. There was little effect of dietary treatment on the organoleptic qualities of milk as assessed by taste panel analysis. There were no effects on the aroma of milk, on aftertaste, or overall liking of the milk. Milk was thicker and creamier in color when cows were fed grass silage compared with red clover silage. The flavor of milk was largely unaffected by dietary treatment. In conclusion, increasing the proportion of red clover in the diet of dairy cows increased feed intakes and milk yields, decreased the concentration of fat and protein in milk, increased PUFA for healthiness, and had little effect on milk organoleptic characteristics.

Triacylglycerol Fatty Acid Composition in Diet-Induced Weight Loss in Subjects with Abnormal Glucose Metabolism – the GENOBIN Study

BackgroundThe effect of weight loss on different plasma lipid subclasses at the molecular level is unknown. The aim of this study was to examine whether a diet-induced weight reduction result in changes in the extended plasma lipid profiles (lipidome) in subjects with features of metabolic syndrome in a 33-week intervention.Methodology/Principal FindingsPlasma samples of 9 subjects in the weight reduction group and 10 subjects in the control group were analyzed using mass spectrometry based lipidomic and fatty acid analyses. Body weight decreased in the weight reduction group by 7.8±2.9% (p<0.01). Most of the serum triacylglycerols and phosphatidylcholines were reduced. The decrease in triacylglycerols affected predominantly the saturated short chain fatty acids. This decrease of saturated short chain fatty acid containing triacylglycerols correlated with the increase of insulin sensitivity. However, levels of several longer chain fatty acids, including arachidonic and docosahexanoic acid, were not affected by weight loss. Levels of other lipids known to be associated with obesity such as sphingolipids and lysophosphatidylcholines were not altered by weight reduction.Conclusions/SignificanceDiet-induced weight loss caused significant changes in global lipid profiles in subjects with abnormal glucose metabolism. The observed changes may affect insulin sensitivity and glucose metabolism in these subjects.Trial RegistrationClinicalTrials.gov NCT00621205

Induction of proinflammatory cytokines by long-chain saturated fatty acids in human macrophages

Increased circulating free fatty acids in subjects with type 2 diabetes may contribute to activation of macrophages, and thus the development of atherosclerosis. In this study, we investigated the effect of the saturated fatty acids (SFA) palmitate, stearate, myristate and laurate, and the unsaturated fatty acid linoleate, on the production of proinflammatory cytokines in phorbol ester-differentiated THP-1 cells, a model of human macrophages. Palmitate induced secretion and mRNA expression of TNF-α, IL-8 and IL-1β, and enhanced lipopolysaccharide (LPS)-induced IL-1β secretion. Proinflammatory cytokine secretion was also induced by stearate, but not by the shorter chain SFA, myristate and laurate, or linoleate. Triacsin C abolished the palmitate-induced cytokine secretion, suggesting that palmitate activation to palmitoyl-CoA is required for its effect. Palmitate-induced cytokine secretion was decreased by knockdown of serine palmitoyltransferase and mimicked by C 2-ceramide, indicating that ceramide is involved in palmitate-induced cytokine secretion. Palmitate phosphorylated p38 and JNK kinases, and blocking of these kinases with specific inhibitors diminished the palmitate-induced cytokine secretion. Palmitate also activated the AP-1 (c-Jun) transcription factor. Knockdown of MyD88 reduced the palmitate-induced IL-8, but not TNF-α or IL-1β secretion. In conclusion, our data suggest that the long-chain SFA induce proinflammatory cytokines in human macrophages via pathways involving de novo ceramide synthesis. This might contribute to the activation of macrophages in atherosclerotic plaques, especially in type 2 diabetes.

Contrasting chemical and isotopic compositions of organic matter in Changjiang (Yangtze River) estuarine and East China Sea shelf sediments

To examine the source and preservation of organic matter in the shelf sediments of the East China Sea (ECS), we measured bulk C/N and isotopes, organic biomarkers (n-alkanes and fatty acids) and compound-specific (fatty acids) stable carbon isotope ratios in three sediment cores collected from two sites near the Changjiang Estuary and one in the ECS shelf. Contrasting chemical and isotopic compositions of organic matter were observed between the estuarine and shelf sediments. The concentrations of total n-alkanes and fatty acids in the shelf surface sediments (0–2 cm) were 5–10 times higher than those in estuarine surface sediments but they all decreased rapidly to comparable levels below the surface layer. The compositions of n-alkanes in the estuarine sediments were dominated by C26-C33 long-chain n-alkanes with a strong odd-to-even carbon number predominance. In contrast, the composition of n-alkanes in the shelf sediment was dominated by nC15 to nC22 compounds. Long-chain (>C20) fatty acids (terrestrial biomarkers) accounted for a significantly higher fraction in the estuarine sediments compared to that in the shelf sediment, while short-chain (<C20) saturated and unsaturated fatty acids were more abundant in the shelf surface sediments than in the estuarine sediments. Stable carbon isotopic ratios of individual fatty acids showed a general positive shift from estuarine to shelf sediments, consistent with the variations in bulk δ 13CTOCTOC. These contrasts between the estuarine and shelf sediments indicate that terrestrial organic matter was mainly deposited within the Changjiang Estuary and inner shelf of ECS. Post-depositional diagenetic processes in the surface sediments rapidly altered the chemical compositions and control the preservation of organic matter in the region.

Long-Chain Saturated Fatty Acids Consumption and Risk of Gallstone Disease Among Men

Various saturated fatty acids have different effects on blood lipids and insulin secretion in experiments. The effect of long-term consumption of specific and different classes of saturated fatty acids on the risk of gallstone disease in humans is unknown. We prospectively studied consumption of saturated fatty acids and risk of gallstone disease in a cohort of 44,524 US men from 1986 to 2002. Intake of saturated fatty acids was assessed using a validated semiquantitative food frequency questionnaire. Newly diagnosed gallstone disease was ascertained biennially. During 584,679 person-years of follow-up, we documented 2350 incident cases of gallstone disease, of which 1387 cases required cholecystectomy. Compared with men in the lowest quintile of dietary intake of long-chain saturated fats, after adjustment for age and other potential risk factors, the relative risk of gallstone disease for men in the highest quintile was 1.24 [95% confidence interval (CI), 1.02, 1.50, P for trend = 0.03], and the relative risk of cholecystectomy for men in the highest quintile was 1.41 (CI, 1.09, 1.82, P for trend = 0.008). Consumption of medium-chain saturated fatty acids or short-chain saturated fatty acids was unrelated to the risk. Our results suggest that a higher consumption of long-chain saturated fatty acids may enhance the risk of gallstone disease in men.

Enrichment of decanoic acid in cuphea fatty acids by molecular distillation

The introduction of a new crop often requires the development of new products and purification techniques of either the oil or fatty acids. Most new crops enter the cosmetic market first due to their high rates of return. However, the cosmetic market often demands highly pure and colorless materials. A molecular distillation unit is a powerful method of separation; separation occurs at extremely low pressures, and therefore at reduced temperatures compared with normal distillations and makes it very suitable for cuphea germplasm line PSR-23 ( C. lanceolta × C. viscosissima) fatty acids. Refined cuphea fatty acids, which are mainly short-chain saturated fatty acids such as decanoic acid (C-10), were distilled using a lab-scale centrifugal molecular distillation unit to yield a distillate that was colorless (Gardner color = 1−). The optimal distillation conditions were explored by varying the rotor temperature and flow rate onto the rotor. As the conditions were varied, the distillate and residue were monitored for Gardner color, fatty acid composition, and mass split rate between the distillate and residue. Under a high flow rate (2.23 g/min), enrichment of C-8 and C-10 in the distillate was increased to 96% in a single-pass distillation (rotor temperature = 65 °C) with no unsaturation in the distillate while maintaining a split ratio of 1.5. A high flow, multiple-pass distillation (rotor temperature = 70 °C) of a distillate fraction produced a distillate that was 99.8% saturated fatty acid and 0.2% unsatured with very high split flow ratios. Overall, laboratory distillation of cuphea fatty acids successfully demonstrated the ability to achieve either high quantities of C-8 and C-10 or total saturated samples.

Isolation and characterization of acidic glycosphingolipids from the gill of the Pacific Salmon (Oncorhynchus keta): A novel hybrid-type ganglioside with isoglobo- and neolacto-Series

Monosialosyl gangliosides and sulfoglycolipids in the gill of pacific salmon, Oncorhynchus keta, have been prepared by solvent extraction and DEAE-Sephadex column chromatography. Acidic glycolipid bands (M1-M13) detected by thin layer chromatography were separated by Iatrobeads column chromatography and 13 components were characterized by TLC, compositional analysis, methylation analysis, chemical and enzymatic degradation, liquid secondary ion mass spectrometry and (1)H nuclear magnetic resonance spectroscopy. In addition to the acidic glycolipids with known structures (SM4s, SM3, GM3, LM1, GM1b and V(3)alphaFuc,IV(3)betaGalNAc-GM1a), two fractions (M11 and M13) of unknown monosialosyl gangliosides with TLC mobility slower than GM1a were isolated and characterized as having the following structure with a hybrid of isoglobo- and neolacto-series. [formula: see text] Analysis of fatty acid indicated predominance of C24:1 fatty acid in the upper band (M11) and shorter chain saturated fatty acids in the lower band (M13). The tissue concentrations of M11 and M13 were 1.15 and 0.96 mumol/kg wet weight, respectively.

Structural analysis of a unique hybrid-type ganglioside with isoglobo-, neolacto-, and ganglio-core from the gills of the Pacific salmon ( Oncorhynchus keta)

Monosialosyl gangliosides from the gills of the Pacific salmon, Oncorhynchus keta, have been prepared by solvent extraction and DEAE-Sephadex column chromatography. The unknown acidic glycolipids (M14 and M15) with slower mobility than GM1a on thin-layer chromatography were separated by Iatrobeads column chromatography and were characterized by compositional analysis, methylation analysis, chemical, and enzymatic degradation, negative-ion LSIMS, and 1H nuclear magnetic resonance spectroscopy. Both M14 and M15 contained a same oligosaccharide core with isoglobo-, neolacto-, and ganglio-series as follows: [Display omitted] The only difference between M14 and M15 was in fatty acid acylation. Analysis of the fatty acids indicated a predominance of C24:1 fatty acid in M14 and shorter chain saturated fatty acids, C14:0 and C16:0, in M15.

Structured triglycerides containing caprylic (8:0) and oleic (18:1) fatty acids reduce blood cholesterol concentrations and aortic cholesterol accumulation in hamsters

The effects of structured triglycerides containing one long chain fatty acid (oleic acid, C18:1) and one short chain saturated fatty acid (caprylic acid, 8:0) on lipidemia, liver and aortic cholesterol, and fecal neutral sterol excretion were investigated in male Golden Syrian hamsters fed a hypercholesterolemic regimen consisting of 89.9% commercial ration to which was added 10% coconut oil and 0.1% cholesterol (w/w). After 2 weeks on the HCD diet, the hamsters were bled, following an overnight fast (16 h) and placed into one of three dietary treatments of eight animals each based on similar plasma cholesterol levels. The hamsters either continued on the HCD diet or were placed on diets in which the coconut oil was replaced by one of two structured triglycerides, namely, 1(3),2-dicaproyl-3(1)-oleoylglycerol (OCC) or 1,3-dicaproyl-2-oleoylglycerol (COC) at 10% by weight. Plasma total cholesterol (TC) in hamsters fed the OCC and COC compared to the HCD were reduced 40% and 49%, respectively ( P < 0.05). Similarly, hamsters fed the OCC and COC diets reduced their plasma nonHDL cholesterol levels by 47% and 57%, respectively ( P < 0.05), compared to hamsters fed the HCD after 2 weeks of dietary treatment. Although hamsters fed the OCC (−26%) and COC (−32%) had significantly lower plasma HDL levels compared to HCD, ( P < 0.05), the plasma nonHDL/HDL cholesterol ratio was significantly lower ( P < 0.05) compared to the HCD for the OCC-fed (−27%) and the COC-fed (−38%) hamsters, respectively. Compared to the HCD group, aortic esterified cholesterol was 20% and 53% lower for the OCC and COC groups, respectively, with the latter reaching statistical significance, P < 0.05. In conclusion, the hamsters fed the structured triglyceride oils had lower blood cholesterol levels and lower aortic accumulation of cholesterol compared to the control fed hamsters.

Effects of natural and artificial defoliation on the content and composition of extractive substances in birch leaves

Qualitative and quantitative compositions of extracts of birch (Betula pendula Roth.) leaves after natural and artificial defoliations were studied. Composition of the fraction of total lipids was determined. Overall, 11 fatty acids were identified. Differences between the fatty acid compositions of total lipids in the trees subjected to defoliation, consisting in the increase in quantities of short-chain saturated fatty acids and trienoic acids, were detected. Nine individual compounds--six flavones, two flavanones, and one flavanonol--were isolated from the flavonoid fraction by column chromatography. It was found that the total content of extractive substances in birch leaves as well as amounts of free sterols, triterpene compounds, and flavones decreased 1 year after an artificial defoliation and 1 month after depredation of 75% of birch stands by gypsy moth. On the contrary, the contents of flavanones and flavanonol increased. The assay method proposed may be used for studying the compositions of plant extracts.

Short Communication: Effects of a Monensin Premix on Milk Fatty Acid Content During Subacute Ruminal Acidosis in Dairy Cows

The effects of a monensin premix on milk fatty acid content during grain-induced subacute ruminal acidosis (SARA) in Holstein cows receiving a total mixed ration was investigated. Six multiparous, rumen-fistulated Holstein cows were used in a two-treatment, two-period crossover design with 6-wk periods. Experimental treatments were either a monensin premix or a placebo premix. At the beginning of wk 4, SARA was induced in experimental cows for a 10-d period using a grain challenge model. The administration of a monensin premix elevated milk fat proportion of total short-chain saturated fatty acids (sum of C4 to C15). Milk fat proportions of conjugated linoleic acid isomers were unaffected. Linolenic acid (C18:3n3) proportion in milk fat of monensin-treated cows were lower when compared with placebo-treated cows during the SARA period. Results from this study indicate that dietary supplementation with monensin during SARA had little effect on milk fatty acid content.

Growth performance, carcass quality, meat quality and fatty acid composition of pigs fed diets

Two hundred gilts and 200 barrows, housed within sex in pens of 25, were randomly allotted to two replications of four dietary treatments to determine the effects of incorporating 30, 20, 10 or 0% extruded soybeans (ESB), displacing a commercial protein supplement, in barley-based grower and finisher diets for pigs. Growth, feed intake and carcass quality of the pigs, and meat quality and fatty acid composition of the pork from a random subset of the pigs on test were determined. No sex × diet interactions were observed. ESB inclusion rate had no effect on growth rate; however, per-pen feed consumption decreased numerically with increasing ESB resulting in an improvement in feed efficiency. The 30% ESB inclusion rate increased carcass fat content (P &lt; 0.05) compared with the control, whereas lean content was unaffected. Meat colour and marbling score were similar across all treatments whereas fat and lean firmness was reduced by the 30% ESB inclusion rate (P &lt; 0.05) compared with all other treatments. Increasing ESB in the diet altered the fatty acid content of the pork by decreasing the amount of short-chain saturated and monounsaturated fatty acids and increasing the amount of long-chain polyunsaturated fatty acids (PUFA). The results of this study indicate that ESB can be used as the sole source of supplemental protein in barley-based diets for pigs with no detrimental effects on performance and minimal negative effects on carcass and meat quality. Alteration of fatty acid content of pork from feeding ESB has both positive and negative implications for consumer acceptance by increasing PUFA content while concomitantly increasing the risk of premature oxidation. Key words: Extruded soybeans, pigs, pork, growth, fatty acids, meat quality

Effect of octanoic acid on ethylene-mediated processes in Arabidopsis

We have examined whether octanoic acid (OA) one of the short chain saturated fatty acids (SCSFA), increases ethylene response in the following three ethylene-mediated processes: a) hypocotyl growth in darkness; b) formation of new flowers; c) flower abscission. These processes were examined in the presence or absence of exogenous ethylene in Arabidopsis wild type (WT) and in the ethylene-insensitive mutants, etr1-3 and ein2-1 and in the ethylene over-producer mutant eto1-1. Our results show that OA decreased hypocotyl length of WT in the absence or presence of exogenous ethylene, apparently showing that OA acts via augmentation of ethylene action. However, the hypocotyl growth inhibition could not be ascribed to increased ethylene sensitivity since application of inhibitors of ethylene synthesis (aminoethoxyvinylglycine; AVG) or action (1-methylcyclopropene;1-MCP) to WT seedlings did not prevent specifically the OA-induced growth inhibition. Also, OA inhibited hypocotyl growth in the mutants etr1-3 and ein2-1 in a similar pattern to that obtained in WT. On the other hand, OA had no effect on flower formation neither in WT, etr1-3 and eto1-1, in which ethylene reduced flower formation, nor in the ein2-1 mutant, in which ethylene had no effect. OA also did not increase flower abscission in WT or in the mutants etr1-3 and ein2-1 neither in the absence nor in the presence of ethylene. However, OA has augmented flower abscission in the mutant eto1-1 only in the absence of exogenous ethylene. This result might indicate that the effect of OA on eto1-1 is specific to this mutant and is not due to general deleterious effects inflicted by OA. Taken together, our results show that in general OA does not augment ethylene response in Arabidopsis, but it might affect ethylene action in flower abscission of the ethylene-overproducer mutant.

The biosynthetic incorporation of short-chain linear saturated fatty acids by Acholeplasma laidlawii B may suppress cell growth by perturbing membrane lipid polar headgroup distribution.

Acholeplasma laidlawii B cells made fatty acid auxotrophic by growth in the presence of the biotin-binding agent avidin grow increasingly poorly at 37 degrees C when supplemented with single exogenous linear saturated fatty acids of decreasing hydrocarbon chain length. Interestingly, this progressive decrease in growth yields with decreasing hydrocarbon chain length is not observed when cells are cultured in the presence of other classes of exogenous fatty acids. Moreover, normal growth is observed is other types of fatty acids with equivalent or shorter hydrocarbon chain lengths, indicating that poor growth in the presence of short-chain linear saturated fatty acids cannot be due to a decrease in membrane lipid bilayer thickness per se. To understand the molecular basis of such growth inhibition, we determined the growth yields, membrane lipid fatty acid and polar headgroups compositions, and phase state and fluidity of the membrane lipids in cells progressively biosynthetically enriched in tridecanoic acid (13:0) or dodecanoic acid (12:0). The growth of fatty acid auxotrophic A. laidlawii B cells grown in the presence of binary combinations of an exogenous fatty acid which supports normal growth on its own and 13:0 or 12:0 revealed that growth inhibition is not observed until 13:0 and 12:0 biosynthetic incorporation levels reach about 90 and 60 mol %, respectively, after which growth is markedly inhibited. Differential scanning calorimetric analyses of membranes from cells maximally enriched in 13:0 indicate that the lipid gel/liquid-crystalline phase transition temperature is unexpectedly high but that at the growth temperature of 37 degrees C, the membrane lipid bilayer is almost exclusively in the liquid-crystalline state but is certainly not excessively fluid. However, high levels of 13:0 incorporation produce a greatly elevated level of the high melting, reversed nonlamellar phase-preferring lipid component monoglucosyl diacylglycerol, and greatly reduced levels of all other membrane lipid components. This marked elevation of monoglucosyl diacylglycerol levels can be rationalized as a regulatory response which maintains the lamellar/nonlamellar phase-forming propensity of the total membrane lipid mixture relatively constant in the face of the biosynthetic incorporation of increasing quantities of short-chain saturated fatty acids, which favor the lamellar phase. However, this lipid biosynthetic response produces a marked decline in the levels of anionic phospholipid and phosphoglycolipid which are probably required to maintain the minimal negative surface charge density of the lipid bilayer, which we suggest is responsible for the observed growth inhibition. This work shows that the lipid biosynthetic regulatory mechanisms present in this organism may sometimes operate at cross purposes such that it is not possible to simultaneously optimize all of the biologically relevant physical properties of the membrane lipid bilayer.

Palmitate-induced cardiac apoptosis is mediated through CPT-1 but not influenced by glucose and insulin.

To test the hypothesis that regulation of palmitate metabolism, through carnitine palmitoyl transferase-1 (CPT-1) or through alterations of glycolysis, was involved in the pathway of palmitate-mediated cell death, cardiomyocytes were cultured from 7-day-old chick embryos. Palmitate-induced cell death, assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay, was enhanced by carnitine, a cofactor needed for palmitate transport into mitochondria via CPT-1. Carnitine co-incubation with palmitate significantly (P < 0.01) increased the amount of apoptotic cells, assessed by propidium iodine staining and fluorescent-activated cell sorting analysis compared with treatment with either palmitate or carnitine alone. The CPT-1 inhibitor oxfenicine significantly (P < 0.05) blocked the cell death induced by the combination of palmitate and carnitine. The short-chain saturated fatty acid capric acid (100 microM), which is not likely transported by CPT-1, did not significantly affect cell viability, whereas the C18 saturated fatty acid stearic (100 microM) significantly (P < 0.01) reduced cell viability and to a similar extent as palmitate. In contrast, there was no significant alteration of palmitate-induced cell death by cotreatment with 100 nM insulin + 2 g/l glucose or 1 mM lactate, which promote ATP generation by glycolysis rather than fatty acid oxidation. Fumonisin did not alter palmitate-induced cell death or apoptosis, suggesting that the effect of palmitate was not operative through increased ceramide synthesis. These results suggest that oxidation of palmitate through CPT-1 is involved in the production of apoptosis in cardiomyocytes.

Milk Fat Composition and Nutritional Value

The perception of milk has changed over the past 25 years from one of being the ideal food to one of being detrimental nutritionally, mainly due to the fatty acid composition of its fat component. Now however, it has been discovered that milk contains a number of compounds, which may have positive nutritional benefits. It also appears that the association between saturated fatty acids in milk and effects on cholesterol may have been an oversimplification. It is accepted that the hypercholesterolaemic saturated fatty acids in milk fat are confined to lauric (C12:0), myristic (C14:0) and palmitic acid (C16:0) with the shorter chain saturated fatty acids and stearic acid having no cholesterol raising effect. Indeed bovine milk fat contains two fatty acids which may have important beneficial effects on human health, namely conjugated linoleic acid (cis-9,trans-11 linoleic acids – C18:2, CLA) and butyric acid (C4:0). Also monounsaturated fatty acids have been shown to be beneficial in altering the proportions of LDL and HDL cholesterol and it is possible to increase the concentration in milk of the principal monounsaturated fatty acid, oleic acid (C18:1), by optimising the diet of the cow. This paper will discuss nutritional strategies to optimise milk fat composition with particular reference to work from my own Research Centre in relation to oleic acid and CLA.

The composition of saturated fatty acids in plasma phospholipids changes in a way to counteract changes in the mean melting point during pregnancy.

It has been demonstrated that in pathological conditions with an increase in the calculated mean melting point (MMP) of phospholipid (PL) fatty acids (FA) there are changes in the composition of the saturated FA (SFA), which partially counteract this effect: shorter-chain SFA with lower melting points are increased, while longer-chain less fluid SFA are suppressed. The aim of this study was to determine whether there are differences in MMP during pregnancy and in the newborn and, if so, whether similar adaptive changes occur in the composition of the SFA. The FA composition of plasma PL was determined in healthy women (n = 16) twice during pregnancy (15-24 wk and 29-36 wk) and at delivery and in umbilical venous blood obtained at birth. The MMP of maternal PL was significantly higher at delivery compared to mid-gestation, due to a loss of highly unsaturated FA (HUFA) which were replaced by SFA. In addition, changes in the SFA occurred: 16:0 with lower melting point was higher while 18:0 with higher melting point was lower at delivery. MMP of PL FA in umbilical plasma was lower than in maternal plasma at delivery, which was due to higher HUFA content. In contrast to maternal plasma, 16:0 was lower while 18:0, 20:0, and 24:0 were higher in umbilical plasma resulting in a higher MMP of SFA, tending to raise the overall MMP. It can be concluded that, during pregnancy and in the newborn, the FA composition of SFA changes in a way to counteract changes in MMP induced by reduced and increased HUFA, respectively.

Lipid-degrading enzyme activities associated with distribution and degradation of fatty acids in the mixing zone of Altamaha estuarine sediments

To examine the relationship between lipid-degrading enzyme activities and lipid composition in estuarine sediments, lipase activities and fatty acids in surface sediments at different stations along the Altamaha River were determined during a high discharge period. Freshwater sandy sediments from upstream stations were characterized by low organic carbon and low lipid contents. Sediments from the strong mixing zone, where salinities were highly variable, were characterized by high organic carbon and high lipid contents with a predominance of long chain (>C20) saturated fatty acids, derived from terrestrial plants. At the river mouth, total fatty acids in the sediments were at intermediate concentrations, with a predominance of algal fatty acids. Lipase activity in the Altamaha River sediments was associated with certain fatty acid subgroups, i.e. monounsaturated, short-chain saturated, and branched-chain fatty acids. This indicates that these lipases probably were produced by bacteria. There was no significant correlation between lipase activity and terrestrial plant fatty acids (long-chain saturates) or algal fatty acids (polyunsaturates). A 3 month incubation of Altamaha River sediment, collected from the strong mixing zone, was carried out to determine changes in lipase activities and degradation rates of the various fatty acids. Solvent-extractable fatty acids were more readily degraded than bound fatty acids (fatty acids released from the extracted-sediment residue by saponification). Chain length and degree of unsaturation, which were linked to the lipid source, affected fatty acid degradation rates. The presence of water overlying sediment resulted in increased sediment lipase activity during incubation, presumably due to stimulation of microbial processes at the sediment–water interface.

Lipophilization of Lysozyme by Short and Middle Chain Fatty Acids

Hen egg white lysozyme was lipophilized with short and middle chain saturated fatty acids (caproic, capric, or myristic acid). The yield, bactericidal properties, and structural properties of lipophilized lysozymes were investigated. The yield of lipophilization of lysozyme greatly increased with the decrease in the chain length of fatty acid. Lipophilization broadened the bactericidal action of lysozyme to Gram-negative bacteria with little loss of enzymatic activity. The bactericidal activity increased in proportion to the number of bound short chain fatty acids. The thermal stability of lipophilized lysozyme decreased in proportion to the chain length and number of bound fatty acids.