The effect of free fatty acids on spectrin organization in lymphocytes.

Previous studies have shown that cis unsaturated free fatty acids (uFFAs) are able to cause alterations in the normal distribution pattern of certain cytoskeletal proteins in lymphocytes, including tubulin, actin, alpha-actinin, and myosin. The cytoskeletal protein spectrin naturally possesses a marked heterogeneity of distribution among resting T and B lymphocytes isolated from all murine lymphoid organs. In some cells, spectrin is observed in a ring-like staining pattern at the periphery of the cell, reflecting a likely association with the cell membrane; in other cells, spectrin is found within the cytoplasm as a large single aggregate or in several smaller aggregates. Addition of uFFA to freshly isolated murine lymphocytes causes disruption in the latter pattern of spectrin organization. Following short-term incubation (15 min) of tissue-derived lymphocytes (from spleen, thymus, and lymph node) and 1 microgram/mL uFFA (oleic [18:1 cis], linoleic [18:2 cis, cis], arachidonic [20:4], or elaidic [18:1 trans] acid) there is a loss of cytoplasmic aggregates of spectrin and a concomitant increase in cells in which spectrin is diffusely distributed. This effect is not seen when two saturated FFAs (sFFAs) were used. When using DO11.10 cells, a T-cell hybridoma in which nearly all cells constitutively express a cytoplasmic aggregate of spectrin, a similar effect was observed, but greater concentrations (10-20 micrograms/mL) of FFA were needed to obtain the same effect. Addition of calcium to the incubation buffer substantially blocks spectrin reorganization. In several disease states, serum levels of FFA are observed to be excessively high; our data support the hypothesis that cytoskeletal reorganization in lymphocytes may be related to the altered immune function frequently observed in these conditions.     

Modulation by Unsaturated Fatty Acids of Norepinephrine- and Adenosine-Induced Formation of Cyclic AMP in Brain Slices

Abstract: The effect of linoleic acid on the formation of cyclic AMP in the slices of guinea pig cerebral cortex was examined. Treatment of the slices with linoleic acid resulted in an increase of basal and of norepinephrine-stimulated formation of cyclic AMP. The stimulatory effect on the basal level of cyclic AMP was not specific for linoleic acid: the potency of the fatty acid was related to the magnitude of unsaturation. In contrast, the enhancement of norepinephrine-stimulated formation of cyclic AMP seemed relatively specific for linoleic acid and arachidonic acid. Linoleic acid markedly enhanced the stimulated formation of cyclic AMP by histamine and adenosine, as well that by norepinephrine, without affecting that by excitatory amino acids and veratridine. Theophylline, adenosine deaminase, and 2'-deoxyadenosine antagonized the effect of linoleic acid. Linoleic acid enhanced the maximum responses to norepinephrine and adenosine without altering the ED₅₀ values for these agonists. When linoleic acid-treated slices were washed with Krebs-Ringer containing defatted bovine serum albumin, both enhancement of the response to norepinephrine and the amount of [¹⁴C]linoleic acid incorporated in a free form significantly diminished.     

Fatty acids regulate pigmentation via proteasomal degradation of tyrosinase: a new aspect of ubiquitin-proteasome function

Fatty acids are common components of biological membranes that are known to play important roles in intracellular signaling. We report here a novel mechanism by which fatty acids regulate the degradation of tyrosinase, a critical enzyme associated with melanin biosynthesis in melanocytes and melanoma cells. Linoleic acid (unsaturated fatty acid, C18:2) accelerated the spontaneous degradation of tyrosinase, whereas palmitic acid (saturated fatty acid, C16:0) retarded the proteolysis. The linoleic acid-induced acceleration of tyrosinase degradation could be abrogated by inhibitors of proteasomes, the multicatalytic proteinase complexes that selectively degrade intracellular ubiquitinated proteins. Linoleic acid increased the ubiquitination of many cellular proteins, whereas palmitic acid decreased such ubiquitination, as compared with untreated controls, when a proteasome inhibitor was used to stabilize ubiquitinated proteins. Immunoprecipitation analysis also revealed that treatment with fatty acids modulated the ubiquitination of tyrosinase, i.e. linoleic acid increased the amount of ubiquitinated tyrosinase whereas, in contrast, palmitic acid decreased it. Furthermore, confocal immunomicroscopy showed that the colocalization of ubiquitin and tyrosinase was facilitated by linoleic acid and diminished by palmitic acid. Taken together, these data support the view that fatty acids regulate the ubiquitination of tyrosinase and are responsible for modulating the proteasomal degradation of tyrosinase. In broader terms, the function of the ubiquitin-proteasome pathway might be regulated physiologically, at least in part, by fatty acids within cellular membranes.     

Free fatty acids in the serum of patients with alcoholism

Blood free fatty acids and their composition were investigated in 25 alcohol abusers hospitalized for detoxication. Blood samples were collected at the admission to the hospital and following detoxication therapy. Free fatty acids were assayed with Dole's technique whereas their composition with gas chromatography. Liver functioning was evaluated with the aid of the following tests: AspAT, AlAT, AP, bilirubin concentration, and thymol test. An increase in free fatty acids concentration was seen in 12 out of 25 patients prior to detoxication. Blood serum free fatty acids were within normal limits in all except one patient after detoxication. A decrease in linoleic acid levels was seen in both total fatty acids and free fatty acids before detoxication. It is more marked in total fatty acids than in free fatty acids and persists after detoxication. Linoleic acid content in free fatty acids returns to the normal values following detoxication. An increase in oleic acid level accompanying a decrease in linoleic acid concentration is probably secondary to the stimulation with hydrogen excess formed during alcohol fermentation.     

Chlorohydrin formation from unsaturated fatty acids reacted with hypochlorous acid.

Stimulated neutrophils produce hypochlorous acid (HOCl) via the myeloperoxidase-catalyzed reaction of hydrogen peroxide with chloride. The reactions of HOCl with oleic, linoleic, and arachidonic acids both as free fatty acids or bound in phosphatidylcholine have been studied. The products were identified by gas chromatography-mass spectrometry of the methylated and trimethylsilylated derivatives. Oleic acid was converted to the two 9,10-chlorohydrin isomers in near stoichiometric yield. Linoleic acid, at low HOCl:fatty acid ratios, yielded predominantly a mixture of the four possible monochlorohydrin isomers. Bischlorohydrins were also formed, in increasing amounts at higher HOCl concentrations. Arachidonic acid gave a complex mixture of mono- and bischlorohydrins, the relative proportions depending on the amount of HOCl added. Linoleic acid appears to be slightly more reactive than oleic acid with HOCl. Reactions of oleic and linoleic acids with myeloperoxidase, hydrogen peroxide, and chloride gave chlorohydrin products identical to those with HOCl. Lipid chlorohydrins have received little attention as products of reactions of neutrophil oxidants. They are more polar than the parent fatty acids, and if formed in cell membranes could cause disruption to membrane structure. Since cellular targets for HOCl appear to be membrane constituents, chlorohydrin formation from unsaturated lipids could be significant in neutrophil-mediated cytotoxicity.     

The transfer of fatty acids across the sheep placenta

Maternal and fetal plasma concentrations of free fatty acids, triacylglycerols and phospholipids and the profile of their fatty acids were measured in three catheterized and unanaesthetized sheep. Fetal concentrations of all three lipid fractions were low and did not correlate with maternal concentrations. There were no measurable umbilical venous-arterial differences. Linoleic acid concentrations were low in both mother and fetus. The fatty acid composition of fetal adipose tissue, liver, lung and cerebellum of five animals was analysed. Again linoleic acid levels were very low, but phospholipids contained 2-8% arachidonic acid. [14C] linoleic acid and [3H] palmitic acid were infused intravenously into three ewes. Only trace amounts of labelled fatty acids were found in fetal plasma and these were confined to the free fatty acids. 14C-label was incorporated into fetal tissue lipids, but most of this probably was due to fetal lipid synthesis from [14C] acetate or other water-soluble products of maternal [14C] linoleic acid catabolism. It is concluded that only trace amounts of fatty acids cross the sheep placenta. They are derived mainly from the maternal plasma free fatty acids and might just be sufficient to be the source of the small amounts of essential fatty acids found in the lamb fetus, but are insignificant in terms of energy supply or lipid storage.     

Betamethasone activation of CTP: Cholinephosphate cytidylyltransferase is mediated by fatty acids

The purpose of the present study was to determine the mechanisms by which glucocorticoids increase the activity of CTP: cholinephosphate cytidylyltransferase, a key enzyme required for the synthesis of surfactant phosphatidylcholine. Lung cytidylyltransferase exists as an inactive, light form low in lipids (L-form) and an active, heavy form high in lipid content (H-form). In vivo, fatty acids stimulate and aggregate the inactive L-form to the active H-form. In vivo, betamethasone increases the amount of H-form while decreasing the amount of L-form in fetal lung. There is also a coordinate increase in total free fatty acids in the H-form. In the present study, we used gas chromatography–mass spectrometry to measure the fatty acid species associated with the H-forms in fetal rat lung after the mothers were treated with betamethasone (1 mg/kg). In vivo, betamethasone increased the total amount of free fatty acids associated with the H-form by 62%. Further, the hormone selectively increased the mass of myristic and oleic acids in H-form by 52 and 82%, respectively. However, betamethasone produced the greatest increase in the amount of H-form linoleic acid, which increased fourfold relative to control. In vitro, each of the fatty acids increased L-form activity in a dose-dependent manner; however, linoleic acid was the most potent. Linoleic and oleic acids also effectively increased L-form aggregations. These observations suggest that in vivo glucocorticoids elevate the level of specific fatty acids which convert cytidylyltransferase to the active form. © 1995 Wiley-Liss, Inc.     

Comparison of the Effects of Orally Administered Linoleic Acid,and Its Hydroperoxides and Secondary Autoxidation Products on Hepatic Lipid Metabolism in Rats

Linoleic acid, and its hydroperoxides and secondary autoxidation products were orally administered to rats (400 mg/rat). Their effects on hepatic lipid metabolism were examined. Linoleic acid reduced the activities of de novo synthesis of fatty acids and acetyl-CoA carboxylase. It decreased the CoASH level and caused the accumulation of long-chain acyl-CoA. Hydroperoxides changed the compositions of unsaturated fatty acids in the hepatic lipids and lowered the content of neutral lipids. Secondary products stimulated carnitine palmitoyltransferase and decreased the content of neutral lipids. They reduced the activities of de novo synthesis of fatty acids and acetyl-CoA carboxylase, and the levels of CoASH and acetyl-CoA. Thus, the effect of secondary products was apparently different from those of linoleic acid and its hydroperoxides.     

Polyunsaturated fatty acid metabolism in neuroblastoma cells in culture.

Neuroblastoma cell cultures took up linoleic and linolenic acids at approximately equal rates, and incorporated them into a variety of lipid fractions, principally cellular phospholipids. Linoleic acid was preferentially incorporated into choline phosphoglycerides, while most of the radioactivity derived from linolenic acid entered ethanolamine phosphoglycerides. There was no evidence for direct transfer of fatty acids between these two phosphoglyceride fractions. When, after the addition of cytosine arabinoside, cell division was arrested, the entry of labelled fatty acids into ethanolamine and serine phosphoglycerides was reduced, suggesting that these lipids are involved in the formation of new cell membranes. In the ethanolamine phosphoglyceride fraction, phosphatidal ethanolamine (plasmalogen) was the principal acceptor for the higher polyunsaturated fatty acids of the φ 3 series. The ratio of labelled fatty acids entering ethanolamine plasmalogens to that entering ethanolamine phosphoglycerides increased following the addition of cytosine arabinoside, suggesting plasmalogens to be involved in formation of cell processes. The first step in the metabolism of both linoleic and linolenic acid was the addition of a two-carbon unit. Conversion of linoleic acid to higher polyunsaturated fatty acids was slower than the conversion of linolenic acid to its higher analogues. This contrasted with the behaviour of dissociated cultures of normal brain cells which were able to form higher analogues of linoleic and linolenic acids at nearly equal rates.     

The essential dietary fatty acid requirement of the tufted apple budmoth, Platynota idaeusalis

The tufted apple budmoth, Platynota idaeusalis (Walker), was reared non-axenically for two successive generations on a casein-based semisynthetic diet. The qualitative essential fatty acid requirement for growth, development and normal pupal-adult ecdysis was studied using the non-axenic casein-based semisynthetic diets with and without various 99% pure fatty acids. Linoleic or linolenic acids caused accelerated larval development; linoleic, linolenic and arachidonic acids showed similar activity in body weight gain and survival to pupal-adult ecdysis. Linoleic or linolenic acids were active in alleviating wing deformities; arachidonic acid was partially active in alleviating wing deformities at the one dietary concentration evaluated. Activity of arachidonic acid as an essential fatty acid for P. idaeusalis is unique among insects, except for mosquitoes. The essential fatty acid deficiency syndrome of the adult, resulting from the larvae feeding on fat-deficient diets, was greatly reduced when larvae were fed on a diet adequate in essential fatty acid during either their early or late development.     

Activation of bovine platelets induced by long-chain unsaturated fatty acids at just below their lytic concentrations,and its mechanism

The effects of long chain unsaturated fatty acids such as linoleic acid on bovine platelets were examined. Not only linoleic acid, but also oleic and linolenic acid, at just below the concentrations causing marked cell lysis, induced an absorbance decrease of the platelet suspension in the presence of Ca²⁺. Since this absorbance decrease was reversed by the addition of EDTA and moreover aggregate formation was found by macroscopic and microscopic observation, it was concluded that unsaturated fatty acids at just below their lytic concentrations caused platelet aggregation. Unsaturated fatty acids also caused release of adenine nucleotides, but there was a lag time between the release and the aggregation, just as with ADP-induced release, suggesting that the aggregation was independent of the release of ADP. It was revealed that this activation of platelets by unsaturated fatty acids was caused by marked Ca²⁺ uptake into the cytoplasm, resulting from significant membrane perturbation.     

The effects of unsaturated fatty acids on hepatic microsomal drug metabolism and cytochrome P-450

1. The effects of unsaturated fatty acids on drug-metabolizing enzymes in vitro were measured by using rat and rabbit hepatic 9000g supernatant fractions. 2. Unsaturated fatty acids inhibited the hepatic microsomal metabolism of ;type I' drugs with inhibition increasing with unsaturation: arachidonic acid>linolenic acid>linoleic acid>oleic acid. Inhibition was independent of lipid peroxidation. Linoleic acid competitively inhibited the microsomal O-demethylation of p-nitroanisole and the N-demethylation of (+)-benzphetamine. 3. The hepatic microsomal metabolism of ;type II' substrates, aniline and (-)-amphetamine, was not affected by unsaturated fatty acids. 4. The rate of reduction of p-nitrobenzoic acid and Neoprontosil was accelerated by unsaturated fatty acids. 5. Linoleic acid up to 3.5mm did not decelerate the generation of NADPH by rat liver soluble fraction, nor the activity of NADPH-cytochrome c reductase of rat liver microsomes. Hepatic microsomal NADPH oxidase activity was slightly enhanced by added linoleic acid. 6. No measurable disappearance of exogenously added linoleic acid occurred when this fatty acid was incubated with rat liver microsomes and an NADPH source. 7. The unsaturated fatty acids used in this study produced type I spectra when added to rat liver microsomes, and affected several microsomal enzyme activities in a manner characteristic of type I ligands.     

Palmitate protects hepatocytes from oxidative stress and triacylglyceride accumulation by stimulation of nitric oxide synthesis in the presence of high glucose and insulin concentration

Abstract

Excessive flux of free fatty acids (FFA) into the liver contributes to liver impairment in non-alcoholic fatty liver disease (NAFLD). It remains unclear how FFA contribute to impairment of hepatocytes. This study treated hepatocytes with linoleic acid and palmitate to investigate the early event triggering FFA-mediated impairment. It determined cell viability, content of nitrite/nitrate and triacylglycerides (TG), inducible nitric oxide synthase (iNOS) protein, oxidation of cardiolipin (CL) as well as formation of F₂-isoprostanes in the presence of insulin and glucose. Linoleic acid caused significant decrease in cell viability. It is shown that palmitate caused induction of iNOS resulting in increased nitrite/nitrate concentration and slight increase in TG content. Linoleic acid led to a decrease in nitrite/nitrate concentration parallelled by massive TG accumulation in combination with increased oxidation of CL and increased F₂-isoprostane levels. It is concluded that nitric oxide (NO) concentration regulates FFA-dependent TG accumulation and oxidative stress in rat hepatocytes.     

Selective channelling of arachidonic and linoleic acids into glycerolipids of rat hepatocytes in primary culture.

Rat hepatocytes in primary culture were incubated with a mixture of linoleic and arachidonic acid at various total fatty acid/serum albumin molar ratios. Mixed fatty acids were taken up at the same rate and distributed with the same pattern as fatty acids added separately. The rates of total uptake, incorporation into hepatocyte and secreted triacylglycerols and beta-oxidation were linearly related to the fatty acid/albumin ratios, whereas the rate of incorporation into phospholipids was saturable. Neither the uptake rate nor the distribution of both fatty acids considered together varied with the arachidonic acid/linoleic acid molar ratio. Changes in this ratio and in the uptake rate led to significant variations in the respective fate of the fatty acids. The preferential channelling of arachidonic acid versus linoleic acid into beta-oxidation and phosphatidylinositol was greatest at a low uptake rate and then decreased as the uptake rose. Conversely, the preferential channelling of arachidonic acid versus linoleic acid into phosphatidylcholine, but not phosphatidylethanolamine, increased with the uptake rate. Moreover, both arachidonic acid and linoleic acid were preferentially incorporated into the 1-palmitoyl molecular species of phosphatidylcholine and phosphatidylethanolamine at a low uptake rate, and of phosphatidylcholine at a high uptake rate. This could be related to the synthesis of biliary phosphatidylcholine, of which 1-palmitoyl-2-linoleoyl and 1-palmitoyl-2-arachidonoyl are the main molecular species. Linoleic and arachidonic acid were selectively distributed into distinct metabolic pools of triacylglycerol, the intrahepatocyte pool which preferentially incorporated linoleic acid at a low uptake rate and the secreted pool in which the relative enrichment of arachidonic acid increased with the uptake rate. This strengthens the central role of hepatic secretion in the supply of arachidonic acid to peripheral tissues.     

Phosphatidylinositol cycle and its possible involvement in the regulation of cytoskeleton-membrane interactions

Receptor-mediated activation of many cells, including blood platelets, leads to changes at the cytoplasmic side of the membrane. In platelets, phospholipases, such as phospholipase C and phospholipase A2, have been shown to become activated. From phospholipids they generate the second messengers diacylglycerol and inositol phosphate(s) and fatty acids, respectively. At the same time, actin polymerization and reorganization of actin filaments into bundles and networks occurs. Here, the association of lipids, radiolabeled either with saturated (palmitic acid) or unsaturated (arachidonic acid) fatty acids, with the cytoskeletons of resting and activated human blood platelets was studied. The relative binding of lipid components to the cytoskeleton of activated platelets labeled with palmitic acid is six times higher than that of platelets labeled with arachidonic acid. Analysis of lipids associated with isolated cytoskeletons of resting and activated platelets (labeled with palmitic acid) showed a 30-fold increase in the binding of labeled lipids to the cytoskeletal structures during activation. Both diacylglycerol and fatty acids were found to be associated with the cytoskeleton of activated platelets. Gel filtration, chromatofocusing, and immunoprecipitation studies demonstrated tight binding of these lipids to alpha-actinin. alpha-Actinin is one of the proteins that rapidly becomes associated with the cytoskeleton during platelet aggregation; it is also one of the molecules proposed to act as an actin-membrane linker. The results reported indicate a possible participation of alpha-actinin, fatty acids, and the phosphoinositide-derived second messenger diacylglycerol in the regulation of cytoskeleton-membrane interactions. Together with the results of others they suggest a possible involvement of the phosphatidylinositol cycle in the assembly of actin filaments and their anchoring to membranes.     

Changes in linoleic acid during follicular development and inhibition of spontaneous breakdown of germinal vesicles in cumulus-free bovine oocytes.

The fatty-acid composition of follicular fluid from small and large developing follicles was analysed and the effects of saturated and unsaturated fatty acids on spontaneous breakdown of germinal vesicles were investigated. Fatty acids were bound to bovine serum albumin and cultured with oocytes at 100 mumol/l. Linoleic acid (18:2) was the only fatty acid tested that significantly inhibited breakdown of germinal vesicles (P less than 0.01). The effect was dose-dependent and was greatest at 50 mumol fatty acid/l (% breakdown of control, 81.1 +/- 6.8 vs. 50 mumol linoleic acid/l, 35.4 +/- 7.3; P less than 0.02). Linoleic acid was the major fatty acid, constituting about a third of the total fatty acid in the follicular fluid; followed by 18.9 +/- 1.0% and 16.9 +/- 1.3% oleic acid (18:1) in small and large follicles, respectively. Saturated fatty acids accounted for less than 30% of the total fatty acid composition. There was a marked absence of tetraenoic acids in small and large follicles. Proportions of linoleic acid were significantly lower in follicular fluid from large follicles (31.1 +/- 1.2% of total fatty acid) than from small follicles (34.8 +/- 0.7% of total fatty acid) (P less than 0.05) and there was a significant inverse correlation between follicle diameter and percentage of linoleic acid in the follicular fluid (r = -0.6966; P less than 0.05). There was no significant alteration in any other fatty acid during follicular development.(ABSTRACT TRUNCATED AT 250 WORDS)     

The molecular organization of myosin in stress fibers of cultured cells

Antibodies to chicken gizzard myosin, subfragment 1, light chain 20, and light meromyosin were used to visualize myosin in stress fibers of cultured chicken cells. The antibody specificity was tested on purified gizzard proteins and total cell lysates using immunogold silver staining on protein blots. Immunofluorescence on cultured chicken fibroblasts and epithelial cells exhibited a similar staining pattern of antibodies to total myosin, subfragment 1, and light chain 20, whereas the antibodies to light meromyosin showed a substantially different reaction. The electron microscopic distribution of these antibodies was investigated using the indirect and direct immunogold staining method on permeabilized and fixed cells. The indirect approach enabled us to describe the general distribution of myosin in stress fibers. Direct double immunogold labeling, however, provided more detailed information on the orientation of myosin molecules and their localization relative to alpha-actinin: alpha-actinin, identified with antibodies coupled to 10-nm gold, was concentrated in the dense bodies or electron-dense bands of stress fibers, whereas myosin was confined to the intervening electron-lucid regions. Depending on the antibodies used in combination with alpha-actinin, the intervening regions revealed a different staining pattern: antibodies to myosin (reactive with the head portion of nonmuscle myosin) and to light chain 20 (both coupled to 5-nm gold) labeled two opposite bands adjacent to alpha-actinin, and antibodies to light meromyosin (coupled to 5-nm gold) labeled a single central zone. Based on these results, we conclude that myosin in stress fibers is organized into bipolar filaments.     

Fatty-acid composition of serum lipids predicts myocardial infarction.

During a follow-up of five to seven years 33 out of 1222 middle-aged men initially free of coronary heart disease sustained fatal or non-fatal myocardial infarction or died suddenly. The fatty-acid composition of serum triglycerides, phospholipids, and cholesterol esters had been measured at the start of the surveillance in these men and in a control group of 64 men matched for age, serum cholesterol and triglyceride concentrations, blood pressure, obesity, smoking, and one-hour glucose tolerance. Palmitic and stearic acids of phospholipids were significantly higher and linoleic and most polyunsaturated fatty acids, including arachidonic acid and eicosapentaenoic acid, of phospholipids were lower in the subjects who sustained coronary events compared with the controls. Linoleic acid tended to correlate negatively with blood pressure while other polyunsaturated fatty acids, especially eicosapentaenoic acid, exhibited a negative correlation with blood pressure and relative body weight in the controls but not in the subjects who sustained coronary events. These findings suggest that the fatty-acid pattern of serum phospholipids is an independent risk factor for coronary heart disease.     

Altered gene expression pattern in the fatty liver dystrophy mouse reveals impaired insulin-mediated cytoskeleton dynamics.

The mouse fatty liver dystrophy (fld) mutation is characterized by transient hypertriglyceridemia and fatty liver during the neonatal period, followed by development of a peripheral neuropathy. To uncover the metabolic pathway that is disrupted by the fld mutation, we analyzed the altered pattern of gene expression in the fatty liver of fld neonates by representational difference analysis of cDNA. Differentially expressed genes detected include a novel member of the Ras superfamily of small GTP-binding proteins, a novel Ser/Thr kinase, and several actin cytoskeleton-associated proteins including actin, profilin, alpha-actinin, and myosin light chain. Because these proteins have a potential functional link in the propagation of hormone signals, we investigated cytoskeleton dynamics in fld cells in response to hormone treatment. These studies revealed that preadipocytes from fld mice exhibit impaired formation of actin membrane ruffles in response to insulin treatment. These findings suggest that the altered mRNA expression levels detected in fld tissue represent a compensatory response for the nonfunctional fld gene and that the fld gene product may be required for development of normal insulin response.     

Effect of amylose content on the lipids of mature rice grain

Most of the nonstarch lipids in brown rice (Oryza sativa) of three rices differing in amylose content were contributed by bran, germ, polish and subaleurone layer. Nonstarch lipids consisted of 82–91% neutral lipids (of which 73–82% were triglycerides), 7–10% phospholipids and 2–8% glycolipids. Linoleic, oleic and palmitic acids were the major fatty acids. Nonwaxy (24 and 29% amylose) milled rice had proportionally more starch lipids and less nonstarch lipids than waxy (2% amylose) milled rice. Starch lipids were mainly lysophosphatidyl choline, lysophosphatidyl ethanolamine and free fatty acids. The major fatty acids were palmitic and linoleic acids, followed by oleic acid.