Effect of diamide administration on longevity, oxygen consumption, superoxide dismutase, catalase, inorganic peroxides and glutathione in the adult housefly, Musca domestica

The effects of various levels of tetracycline hydrochloride on the feeding habits, larval growth, and the metabolism of lipids, carbohydrates and proteins of Heliothis virescens were studied. Regression analysis showed that larval weight, fatty acids and glycogen decreased exponentially with increasing concentration of antibiotic, whereas protein showed a linear decrease. Larval feeding was initially decreased when antibiotics were added to the diet but there was no difference after 24 hr.     

Organization of lipid reserves in cotyledons of primed and aged sunflower seeds

Imbibing sunflower (Helianthus annuus L., cv. Briosol) seeds at water potentials between –2 MPa and –5 MPa leads to faster (priming) or slower (accelerated ageing) germination depending on the temperature and duration of treatment. Mobilization of food reserves may be associated with the changes in seed vigor. To study this, morphological, biochemical and phase properties of lipid, the major food reserve in sunflower, were compared in freshly harvested (i.e., control), primed and aged sunflower cotyledons using electron microscopy, biochemical analyses and differential scanning calorimetry, respectively. Lipid bodies became smaller and more dispersed throughout the cytoplasm during priming and ageing. Despite ultrastructural changes, there were few measured changes in biochemistry of the neutral lipid component; lipid content, proportion of saturated and unsaturated fatty acids and level of free fatty acids were unchanged in primed and slightly aged seeds, with only severely aged seeds showing a net decrease in polyunsaturated fatty acids and an increase in free fatty acids. Subtle changes in the calorimetric behavior of lipids within sunflower cotyledons were observed. Sunflower lipids exhibited polymorphic crystalline and amorphous solid phases when cooled to <–100°C, but priming decreased the rate of crystallization in vivo and ageing increased the rate of crystallization, but decreased percentage crystallinity. The observed changes in thermal behavior in vivo are consistent with losses and gains, respectively, of interacting non-lipid moieties in the triacylglycerol matrix.     

Complex I-Associated Hydrogen Peroxide Production Is Decreased and Electron Transport Chain Enzyme Activities Are Altered in n-3 Enriched fat-1 Mice

The polyunsaturated nature of n-3 fatty acids makes them prone to oxidative damage. However, it is not clear if n-3 fatty acids are simply a passive site for oxidative attack or if they also modulate mitochondrial reactive oxygen species (ROS) production. The present study used fat-1 transgenic mice, that are capable of synthesizing n-3 fatty acids, to investigate the influence of increases in n-3 fatty acids and resultant decreases in the n-6∶n-3 ratio on liver mitochondrial H₂O₂ production and electron transport chain (ETC) activity. There was an increase in n-3 fatty acids and a decrease in the n-6∶n-3 ratio in liver mitochondria from the fat-1 compared to control mice. This change was largely due to alterations in the fatty acid composition of phosphatidylcholine and phosphatidylethanolamine, with only a small percentage of fatty acids in cardiolipin being altered in the fat-1 animals. The lipid changes in the fat-1 mice were associated with a decrease (p<0.05) in the activity of ETC complex I and increases (p<0.05) in the activities of complexes III and IV. Mitochondrial H₂O₂ production with either succinate or succinate/glutamate/malate substrates was also decreased (p<0.05) in the fat-1 mice. This change in H₂O₂ production was due to a decrease in ROS production from ETC complex I in the fat-1 animals. These results indicate that the fatty acid changes in fat-1 liver mitochondria may at least partially oppose oxidative stress by limiting ROS production from ETC complex I.     

Modulation of antioxidant enzyme activities, platelet aggregation and serum prostaglandins in rats fed spray-dried milk containing n-3 fatty acid

Spray-dried milk enriched with n-3 fatty acids from linseed oil (LSO) or fish oil (FO) were fed to rats to study its influence on liver lipid peroxides, hepatic antioxidant enzyme activities, serum prostaglandins and platelet aggregation. Significant level of α linolenic acid, eicosapentaenoic acid and docosahexaenoic acid were accumulated at the expense of arachidonic acid in the liver of rats fed n-3 fatty acid enriched formulation. The linseed oil and fish oil enriched formulation fed group had 44 and 112% higher level of lipid peroxides in liver homogenate compared to control rats fed groundnut oil enriched formulation. Catalase activity in liver homogenate was increased by 37 and 183% respectively in linseed oil and fish oil formulation fed rats. The glutathione peroxidase activity decreased to an extent of 25–36% and glutathione transferase activity increased to an extent of 34–39% in rats fed n-3 fatty acids enriched formulation. Feeding n-3 fatty acid enriched formulation significantly elevated the n-3 fatty acids in platelets and increased the lipid peroxide level to an extent of 4.2 to 4.5-fold compared to control. The serum thromboxane B₂ level was decreased by 35 and 42% respectively in linseed oil and fish oil enriched formulation fed rats, whereas 6-keto-prostaglandin F1α level was decreased by 17 and 23% respectively in linseed oil and fish oil enriched formulation fed rats. The extent and rate of platelet aggregation was decreased significantly in n-3 fatty acids enriched formulation fed rats. This indicated that n-3 fatty acids enriched formulation beneficially reduces platelet aggregation and also enhances the activities of hepatic antioxidant enzymes such as catalase and glutathione transferase.     

Effects of Sieving, Storage, and Incubation Temperature on the Phospholipid Fatty Acid Profile of a Soil Microbial Community

Disturbances typically associated with the study of soil microbial communities, i.e., sieving, storage, and subsequent incubation at elevated temperatures, were investigated with phospholipid fatty acid (PLFA) analyses. Treatment effects were quantified by statistical analyses of the mole percentage distribution of the individual fatty acids. Changes in the concentrations of individual fatty acids over a 7-week storage period at 4.5°C were generally not statistically significant. Sieving effects (mesh size, 4 or 2 mm) on CO₂ evolution and the PLFA profile were monitored over 3 weeks; the physical disturbance had only minor effects, although some damage to fungal hyphae by the first sieving (<4 mm) was suggested by a decrease in the signature fatty acid 18:2 ω6c. Temperature effects were investigated by incubating soil for up to 3 weeks at 4.5, 10, or 25°C. Principal component analyses demonstrated a significant shift in the PLFA composition at 25°C over the first 2 weeks, while changes at the other two temperatures were minor. Several of the changes observed at 25°C could be explained with reference to mechanisms of temperature adaptation or as a response to conditions of stress, including a decrease in the degree of unsaturation, an increased production of cyclopropyl fatty acids, and increased ratios of the branched-chain fatty acids iso-15:0 and iso-17:0 over anteiso-15:0 and anteiso-17:0, respectively. A decrease in the total amount of PLFA was also indicated.     

Starvation Response of the Marine Barophile CNPT-3

The psychrophilic marine barophile CNPT-3 underwent a starvation-survival response similar to that reported for the marine bacteria Ant-300, DW1, and S-14. The number of culturable cells increased initially and then decreased gradually over a 24-day starvation period, with corresponding decreases in total cell number and direct viability count. A significant reduction in cell size and biovolume accompanied these changes. Starved cells demonstrated a greater tendency to attach at the in situ pressure (400 atm; ca. 40.5 MPa) and temperature (5°C) than at 1 atm (ca. 101 kPa), and the extent of attachment increased with increasing duration of starvation. The membrane fatty acid profile of the marine barophile CNPT-3 was studied as the cells were subjected to starvation conditions. A 37.5% increase in saturated fatty acids was observed during the first 8 days of starvation, with a concomitant decrease in unsaturated fatty acids. There was also an increase in the amount of short-chain (<C_15:0) fatty acids.     

Influence of selected sugars and temperature on fatty acids composition in Candida lipolytica

Summary An investigation was made of the effects of temperature and of mono- and disaccharides on lipids, biomass, odd-chain and unsaturated fatty acids production of Candida lipolytica. With different sugars as carbon source at 30°C, the order for biomass production was: fructose > glucose > sucrose > lactose > galactose, while lipids production/g biomass decreased as follows: lactose, sucrose, galactose, fructose and glucose. On the other hand, the odd-chain fatty acids contents decreased in the following order: fructose, lactose, glucose, sucrose and galactose. Lowering the temperature of cultivation to 15°C, biomass, lipids and unsaturated fatty acids decreased. However, a notable decrease in the content of odd-chain fatty acids was detected.     

Fatty-Acid Composition of Candida utilis as Affected by Growth Temperature and Dissolved-Oxygen Tension

Analyses were made of the fatty-acid composition of Candida utilis NCYC 321 grown in a chemostat at a dilution rate (equal to growth rate) of 0.1 hr⁻¹ and at temperatures in the range of 30 to 15 C and dissolved oxygen tensions between 75 and <1 mm of Hg. Cells grown under glucose limitation or NH₄⁺ limitation contained mainly C_16:0, C_16:1, C_18:0, C_18:1, C_18:2, and C_18:3 acids as detected by gas-liquid chromatography of methyl esters of the acids from lipids extracted with chloroform-methanol. The relative proportions of these acids varied with the growth temperature and the dissolved-oxygen tension in the culture. A decrease in growth temperature from 30 to 20 C led to an increased synthesis of unsaturated acids in cells grown under either limitation at a fixed-oxygen tension in the range of 75 to 5 mm of Hg. In cultures with a dissolved-oxygen tension of 1 and <1 mm of Hg, a further decrease in temperature to 15 C caused an increased synthesis of unsaturated fatty acids. A decrease in dissolved-oxygen tension led to a diminished synthesis of unsaturated fatty acids in cells grown at a fixed temperature under either limitation. Cells grown at a fixed temperature under glucose limitation synthesized a greater proportion of C₁₆ acids at the expense of C₁₈ acids as the dissolved oxygen tension was decreased from 75 to <1 mm of Hg. A preferential synthesis of C₁₆ acids also occurred as the growth temperature was decreased from 30 to 15 C in cells grown under glucose limitation at a fixed-oxygen tension. The same effect was observed in cells grown under NH₄⁺ limitation when the temperature was lowered from 30 to 20 C; but when the temperature was decreased further to 15 C, the cells synthesized a slightly greater proportion of C₁₈ acids. Synthesis of a large proportion of C₁₆ acids was accompanied by an excretion of pyruvate, and occasionally traces of 2-ketoglutarate, and an increased intracellular accumulation of certain amino acids.     

Soil Bacterial Biomass, Activity, Phospholipid Fatty Acid Pattern, and pH Tolerance in an Area Polluted with Alkaline Dust Deposition

Soil bacterial biomass, phospholipid fatty acid pattern, pH tolerance, and growth rate were studied in a forest area in Finland that is polluted with alkaline dust from an iron and steel works. The pollution raised the pH of the humus layer from 4.1 to 6.6. Total bacterial numbers and the total amounts of bacterial phospholipid fatty acids in the humus layer did not differ between the unpolluted control sites and the polluted ones. The number of CFU increased by a factor of 6.4 in the polluted sites compared with the controls, while the bacterial growth rate, measured by the thymidine incorporation technique, increased about 1.8-fold in the polluted sites. A shift in the pattern of phospholipid fatty acids indicated a shift in the bacterial species composition. The largest proportional increase was found for the fatty acid 10Me18:0, which indicated an increase in the number of actinomycetes in the polluted sites. The levels of the fatty acids i14:0, 16:1ω5, cy17:0, 18:1ω7, and 19:1 also increased in the polluted sites while those of fatty acids 15:0, i15:0, 10Me16:0, 16:1ω7t, 18:1ω9, and cy19:0 decreased compared with the unpolluted sites. An altered pH tolerance of the bacterial assemblage was detected either as a decrease in acid-tolerant CFU in the polluted sites or as altered bacterial growth rates at different pHs. The latter was estimated by measuring the thymidine incorporation rate of bacteria extracted from soil by homogenization-centrifugation at different pHs.     

Differential Effects of Permeating and Nonpermeating Solutes on the Fatty Acid Composition of Pseudomonas putida

We examined the effect of reduced water availability on the fatty acid composition of Pseudomonas putida strain mt-2 grown in a defined medium in which the water potential was lowered with the permeating solutes NaCl or polyethylene glycol (PEG) with a molecular weight of 200 (PEG 200) or the nonpermeating solute PEG 8000. Transmission electron microscopy showed that −1.0-MPa PEG 8000-treated cells had convoluted outer membranes, whereas −1.0-MPa NaCl-treated or control cells did not. At the range of water potential (−0.25 to −1.5 MPa) that we examined, reduced water availability imposed by PEG 8000, but not by NaCl or PEG 200, significantly altered the amounts of trans and cis isomers of monounsaturated fatty acids that were present in whole-cell fatty acid extracts. Cells grown in basal medium or under the −0.25-MPa water potential imposed by NaCl or PEG 200 had a higher trans:cis ratio than −0.25-MPa PEG 8000-treated cells. As the water potential was lowered further with PEG 8000 amendments, there was an increase in the amount of trans isomers, resulting in a higher trans:cis ratio. Similar results were observed in cells grown physically separated from PEG 8000, indicating that these changes were not due to PEG toxicity. When cells grown in −1.5-MPa PEG 8000 amendments were exposed to a rapid water potential increase of 1.5 MPa or to a thermodynamically equivalent concentration of the permeating solute, NaCl, there was a decrease in the amount of trans fatty acids with a corresponding increase in the cis isomer. The decrease in the trans/cis ratio following hypoosomotic shock did not occur in the presence of the lipid synthesis inhibitor cerulenin or the growth inhibitors chloramphenicol and rifampicin, which indicates a constitutively operating enzyme system. These results indicate that thermodynamically equivalent concentrations of permeating and nonpermeating solutes have unique effects on membrane fatty acid composition.     

Correlation between fluidity and fatty acid composition of phospholipid species in Tetrahymena pyriformis during temperature acclimation

The correlation between the fluidity of phospholipids and their fatty acid composition was studied by spin label technique and gas-liquid chromatography for three major phospholipid species in Tetrahymena pyriformis during temperature acclimation. The fluidity of 2-aminoethylphosphonolipid increased within the first 10 h of the cold-acclimation when the content of γ-linolenic acid in 2-aminoethylphosphonolipid was highest, and it then decreased up to 24 h. On the other hand, the fluidities of phosphatidylethanolamine and phosphatidylcholine showed a gradual decrease up to 24 h after the temperature shift, although γ-linolenic acid contents were highest at 10 h after the temperature shift. Thus the fluidity changes of these two phospholipids were interpreted as resulting from the altered content of other fatty acids in addition to γ-linolenic acid, since the γ-linolenic acid content was smaller than that of 2-aminoethylphosphonolipid. The results suggest that the content of γ-linolenic acid in 2-aminoethylphosphonolipid plays a role in regulating the thermal adaptation process.     

Heterologous Production of Dihomo-γ-Linolenic Acid in Saccharomyces cerevisiae

To make dihomo-γ-linolenic acid (DGLA) (20:3n-6) in Saccharomyces cerevisiae, we introduced Kluyveromyces lactis Δ12 fatty acid desaturase, rat Δ6 fatty acid desaturase, and rat elongase genes. Because Fad2p is able to convert the endogenous oleic acid to linoleic acid, this allowed DGLA biosynthesis without the need to supply exogenous fatty acids on the media. Medium composition, cultivation temperature, and incubation time were examined to improve the yield of DGLA. Fatty acid content was increased by changing the medium from a standard synthetic dropout medium to a nitrogen-limited minimal medium (NSD). Production of DGLA was higher in the cells grown at 15°C than in those grown at 20°C, and no DGLA production was observed in the cells grown at 30°C. In NSD at 15°C, fatty acid content increased up until day 7 and decreased after day 10. When the cells were grown in NSD for 7 days at 15°C, the yield of DGLA reached 2.19 μg/mg of cells (dry weight) and the composition of DGLA to total fatty acids was 2.74%. To our knowledge, this is the first report describing the production of polyunsaturated fatty acids in S. cerevisiae without supplying the exogenous fatty acids.     

Fasting enriches liver triacylglycerol with n-3 polyunsaturated fatty acids: implications for understanding the adipose–liver axis in serum docosahexaenoic acid regulation

We investigated the effect of short-term fasting on coordinate changes in the fatty acid composition of adipose triacylglycerol (TAG), serum non-esterified fatty acids (NEFA), liver TAG, and serum TAG and phospholipids in mice fed ad libitum or fasted for 16 h overnight. In contrast to previous reports under conditions of maximal lipolysis, adipose tissue TAG was not preferentially depleted of n-3 PUFA or any specific fatty acids, nor were there any striking changes in the serum NEFA composition. Short-term fasting did, however, increase the hepatic proportion of n-3 PUFA, and almost all individual species of n-3 PUFA showed relative and absolute increases. The relative proportion of n-6 PUFA in liver TAG also increased but to a lesser extent, resulting in a significant decrease in the n-6:n-3 PUFA ratio (from 14.3 ± 2.54 to 9.6 ± 1.20), while the proportion of MUFA decreased significantly and SFA proportion did not change. Examination of genes involved in PUFA synthesis suggested that hepatic changes in the elongation and desaturation of precursor lipids could not explain this effect. Rather, an increase in the expression of fatty acid transporters specific for 22:6n-3 and other long-chain n-3 and n-6 PUFA likely mediated the observed hepatic enrichment. Analysis of serum phospholipids indicated a specific increase in the concentration of 22:6n-3 and 16:0, suggesting increased specific synthesis of DHA-enriched phospholipid by the liver for recirculation. Given the importance of blood phospholipid in distributing DHA to neural tissue, these findings have implications for understanding the adipose–liver–brain axis in n-3 PUFA metabolism.

Electronic supplementary material

The online version of this article (doi:10.1007/s12263-015-0490-2) contains supplementary material, which is available to authorized users.     

Individual Variation in Lipidomic Profiles of Healthy Subjects in Response to Omega-3 Fatty Acids

Introduction

Conflicting findings in both interventional and observational studies have resulted in a lack of consensus on the benefits of ω3 fatty acids in reducing disease risk. This may be due to individual variability in response. We used a multi-platform lipidomic approach to investigate both the consistent and inconsistent responses of individuals comprehensively to a defined ω3 intervention.

Methods

The lipidomic profile including fatty acids, lipid classes, lipoprotein distribution, and oxylipins was examined multi- and uni-variately in 12 healthy subjects pre vs. post six weeks of ω3 fatty acids (1.9 g/d eicosapentaenoic acid [EPA] and 1.5 g/d docosahexaenoic acid [DHA]).

Results

Total lipidomic and oxylipin profiles were significantly different pre vs. post treatment across all subjects (p=0.00007 and p=0.00002 respectively). There was a strong correlation between oxylipin profiles and EPA and DHA incorporated into different lipid classes (r²=0.93). However, strikingly divergent responses among individuals were also observed. Both ω3 and ω6 fatty acid metabolites displayed a large degree of variation among the subjects. For example, in half of the subjects, two arachidonic acid cyclooxygenase products, prostaglandin E₂ (PGE₂) and thromboxane B2 (TXB₂), and a lipoxygenase product, 12-hydroxyeicosatetraenoic acid (12-HETE) significantly decreased post intervention, whereas in the other half they either did not change or increased. The EPA lipoxygenase metabolite 12-hydroxyeicosapentaenoic acid (12-HEPE) varied among subjects from an 82% decrease to a 5,000% increase.

Conclusions

Our results show that certain defined responses to ω3 fatty acid intervention were consistent across all subjects. However, there was also a high degree of inter-individual variability in certain aspects of lipid metabolism. This lipidomic based phenotyping approach demonstrated that individual responsiveness to ω3 fatty acids is highly variable and measurable, and could be used as a means to assess the effectiveness of ω3 interventions in modifying disease risk and determining metabolic phenotype.     

Adaptive Changes in Membrane Lipids of Barophilic Bacteria in Response to Changes in Growth Pressure

The lipid compositions of barophilic bacterial strains which contained docosahexaenoic acid (DHA [22:6n-3]) were examined, and the adaptive changes of these compositions were analyzed in response to growth pressure. In the facultatively barophilic strain 16C1, phosphatidylethanolamine (PE) and phosphatidylglycerol (PG) were major components which had the same fatty acid chains. However, in PE, monounsaturated fatty acids such as hexadecenoic acid were major components, and DHA accounted for only 3.7% of the total fatty acids, while in PG, DHA accounted for 29.6% of the total fatty acids. In response to an increase in growth pressure in strain 16C1, the amounts of saturated fatty acids in PE were reduced, and these decreases were mainly balanced by an increase in unsaturated fatty acids, including DHA. In PG, the decrease in saturated fatty acids was mainly balanced by an increase in DHA. Similar adaptive changes in fatty acid composition were observed in response to growth pressure in obligately barophilic strain 2D2. Furthermore, these adaptive changes in response were also observed in response to low temperature in strain 16C1. These results confirm that the general shift from saturated to unsaturated fatty acids including DHA is one of the adaptive changes in response to increases in pressure and suggest that DHA may play a role in maintaining the proper fluidity of membrane lipids under high pressure.     

Kinetics of n-3 fatty acids in Brachionus plicatilis and changes in the food supply

Moderately starved rotifers exhibited a two-phased increase in n-3 fatty acids when they were fed a diet rich in these fatty acids. The first 20–30 min of enrichment, the increase in n-3 fatty acids was primarily due to increased gut content. The subsequent slow increase was due to an incorporation of n-3 fatty acids into rotifers tissues. Saturation was achieved before 24 h of exposure and the saturation level was independent of the initial content of n-3 fatty acids in the rotifers.Starvation and limited feeding of the enriched rotifers for additional 4–8 h at 10–20 °C did not affect the accumulated fatty acids significantly. This was found for rotifers with high and low initial content of n-3 fatty acids. The n-3 fatty acids were assimilated with high efficiency from the feed and were not metabolized faster than other groups of fatty acids.Enriched rotifers retained their nutritional value for a sufficient period after enrichment to serve well as live feed for marine fish larvae.     

Effect of alterations in membrane lipid unsaturation on the properties of the insulin receptor of Ehrlich ascites cells

We have altered the phospholipid composition of the plasma membranes of Ehrlich ascites cells grown in mice and studied the effects on the properties of the insulin receptor of this cell. The insulin receptor of the Ehrlich cell demonstrated all of the binding characteristics of mammalian insulin receptors: specificity for insulin and insulin analogs, saturability, inverse relationship of steady-state binding levels to temperature, and negative cooperativity. Cellular phospholipids enriched in monounsaturated fatty acyl groups were produced by growth in animals that were maintained on a diet rich in coconut oil; cellular phospholipids enriched in polyunsaturated fatty acyl groups were produced in animals fed sunflower oil. Insulin receptors were present in the normal cells at 180 000 sites/cell but this fell to 125 000 (p <0.001) in cells enriched in monounsaturated fatty acids and rose to 386 000 (p <0.001) in cells enriched in polyunsaturated fatty acids. The normal cells had affinity constants ( and ) of 0.03 and 0.01 nM⁻¹. The cells enriched in monounsaturated fatty acids had an increase in these affinity constants to 0.06 and 0.03 nM⁻¹ whereas values of 0.01 and 0.005 nM⁻¹ were obtained in the cells enriched in polyunsaturated fatty acids (all comparison p <0.001). Thus, increased unsaturation of plasma membrane phospholipids, produced by dietary manipulations, was associated with an increase in insulin receptor number but a decrease in binding affinity. In contrast, increased saturation of the phospholipids of the plasma membrane was associated with a decrease in receptor number and an increase in affinity. The results can be explained by a model in which the insulin receptor is assumed to be multimeric.     

Selective Enrichment of Omega-3 Fatty Acids in Oils by Phospholipase A1

Omega fatty acids are recognized as key nutrients for healthier ageing. Lipases are used to release ω-3 fatty acids from oils for preparing enriched ω-3 fatty acid supplements. However, use of lipases in enrichment of ω-3 fatty acids is limited due to their insufficient specificity for ω-3 fatty acids. In this study use of phospholipase A1 (PLA1), which possesses both sn-1 specific activity on phospholipids and lipase activity, was explored for hydrolysis of ω-3 fatty acids from anchovy oil. Substrate specificity of PLA1 from Thermomyces lenuginosus was initially tested with synthetic p-nitrophenyl esters along with a lipase from Bacillus subtilis (BSL), as a lipase control. Gas chromatographic characterization of the hydrolysate obtained upon treatment of anchovy oil with these enzymes indicated a selective retention of ω-3 fatty acids in the triglyceride fraction by PLA1 and not by BSL. ¹³C NMR spectroscopy based position analysis of fatty acids in enzyme treated and untreated samples indicated that PLA1 preferably retained ω-3 fatty acids in oil, while saturated fatty acids were hydrolysed irrespective of their position. Hydrolysis of structured triglyceride,1,3-dioleoyl-2-palmitoylglycerol, suggested that both the enzymes hydrolyse the fatty acids at both the positions. The observed discrimination against ω-3 fatty acids by PLA1 appears to be due to its fatty acid selectivity rather than positional specificity. These studies suggest that PLA1 could be used as a potential enzyme for selective concentrationof ω-3 fatty acids.     

Control of glycolysis and gluconeogenesis in rat kidney cortex slices

1. Glucose uptake or glucose formation has been studied in kidney cortex slices to investigate metabolic control of phosphofructokinase and fructose-diphosphatase activities. 2. Glucose uptake is increased and glucose formation is decreased by anoxia, cyanide or an uncoupling agent. Under these conditions the intracellular concentrations of glucose 6-phosphate and ATP decreased whereas that of fructose diphosphate either increased or remained constant, and the concentrations of AMP and ADP increased. 3. Glucose uptake was decreased, and glucose formation from glycerol or dihydroxyacetone was increased, by the presence of ketone bodies or fatty acids, or after starvation of the donor animal. Under these conditions, the concentrations of glucose 6-phosphate and citrate were increased, whereas those of fructose diphosphate and the adenine nucleotides were unchanged (see also Newsholme & Underwood, 1966). 4. It is concluded that anoxia and cell poisons increase glucose uptake and decrease gluconeogenesis by stimulating phosphofructokinase and inhibiting fructose diphosphatase, whereas ketone bodies, fatty acids or starvation increase gluconeogenesis and decrease glucose uptake through the citrate inhibition of phosphofructokinase.     

Organic Production Enhances Milk Nutritional Quality by Shifting Fatty Acid Composition: A United States–Wide, 18-Month Study

Over the last century, intakes of omega-6 (ω-6) fatty acids in Western diets have dramatically increased, while omega-3 (ω-3) intakes have fallen. Resulting ω-6/ω-3 intake ratios have risen to nutritionally undesirable levels, generally 10 to 15, compared to a possible optimal ratio near 2.3. We report results of the first large-scale, nationwide study of fatty acids in U.S. organic and conventional milk. Averaged over 12 months, organic milk contained 25% less ω-6 fatty acids and 62% more ω-3 fatty acids than conventional milk, yielding a 2.5-fold higher ω-6/ω-3 ratio in conventional compared to organic milk (5.77 vs. 2.28). All individual ω-3 fatty acid concentrations were higher in organic milk—α-linolenic acid (by 60%), eicosapentaenoic acid (32%), and docosapentaenoic acid (19%)—as was the concentration of conjugated linoleic acid (18%). We report mostly moderate regional and seasonal variability in milk fatty acid profiles. Hypothetical diets of adult women were modeled to assess milk fatty-acid-driven differences in overall dietary ω-6/ω-3 ratios. Diets varied according to three choices: high instead of moderate dairy consumption; organic vs. conventional dairy products; and reduced vs. typical consumption of ω-6 fatty acids. The three choices together would decrease the ω-6/ω-3 ratio among adult women by ∼80% of the total decrease needed to reach a target ratio of 2.3, with relative impact “switch to low ω-6 foods” > “switch to organic dairy products” ≈ “increase consumption of conventional dairy products.” Based on recommended servings of dairy products and seafoods, dairy products supply far more α-linolenic acid than seafoods, about one-third as much eicosapentaenoic acid, and slightly more docosapentaenoic acid, but negligible docosahexaenoic acid. We conclude that consumers have viable options to reduce average ω-6/ω-3 intake ratios, thereby reducing or eliminating probable risk factors for a wide range of developmental and chronic health problems.