脂肪酸对红火蚁搬尸行为的影响

【目的】工蚁死亡后易受病原菌的侵染,进而危害蚁巢的健康。为了避免病菌横向传播,活工蚁根据尸体体内特定的化学物质的变化来识别尸体并将其搬运到弃尸堆。本实验旨在研究6种脂肪酸(油酸、亚油酸、棕榈油酸、棕榈酸、硬脂酸和肉豆蔻酸)对红火蚁Solenopsis invicta工蚁搬尸行为的影响,明确不同脂肪酸在其搬尸行为中发挥的作用。【方法】本实验利用GC-MS分析了工蚁活体和尸体提取物的脂肪酸成分,并在室内用滤纸片法测定了红火蚁对6种脂肪酸(10 μg/μL)、不同浓度(0.75和3 μg/μL)的单组分油酸或亚油酸以及不同浓度(0.01, 0.1, 1和10 μg/μL)的这两种酸的混合液的反应。【结果】结果表明,红火蚁尸体仅含有亚油酸和油酸两种脂肪酸;另外4种脂肪酸(棕榈油酸、棕榈酸、硬脂酸和肉豆蔻酸)对红火蚁的搬尸行为无显著影响;单组分的油酸和亚油酸均能促进红火蚁的搬尸行为,浓度越高,搬尸行为越显著。10 μg/μL的油酸和亚油酸混合液对工蚁的搬尸行为也具有显著的促进效果,低浓度的混合液对其无明显的促进作用(P>0.05)。【结论】结果提示油酸和亚油酸可调控红火蚁的搬尸行为,其他脂肪酸对红火蚁搬尸行为不产生影响。     

Responses to oleic,linoleic and α-linolenic acids in high-carbohydrate,high-fat diet-induced metabolic syndrome in rats

We investigated the changes in adiposity, cardiovascular and liver structure and function, and tissue fatty acid compositions in response to oleic acid-rich macadamia oil, linoleic acid-rich safflower oil and α-linolenic acid-rich flaxseed oil (C18 unsaturated fatty acids) in rats fed either a diet high in simple sugars and mainly saturated fats or a diet high in polysaccharides (cornstarch) and low in fat. The fatty acids induced lipid redistribution away from the abdomen, more pronounced with increasing unsaturation; only oleic acid increased whole-body adiposity. Oleic acid decreased plasma total cholesterol without changing triglycerides and nonesterified fatty acids, whereas linoleic and α-linolenic acids decreased plasma triglycerides and nonesterified fatty acids but not cholesterol. α-Linolenic acid improved left ventricular structure and function, diastolic stiffness and systolic blood pressure. Neither oleic nor linoleic acid changed the left ventricular remodeling induced by high-carbohydrate, high-fat diet, but both induced dilation of the left ventricle and functional deterioration in low fat-diet-fed rats. α-Linolenic acid improved glucose tolerance, while oleic and linoleic acids increased basal plasma glucose concentrations. Oleic and α-linolenic acids, but not linoleic acid, normalized systolic blood pressure. Only oleic acid reduced plasma markers of liver damage. The C18 unsaturated fatty acids reduced trans fatty acids in the heart, liver and skeletal muscle with lowered stearoyl-CoA desaturase-1 activity index; linoleic and α-linolenic acids increased accumulation of their C22 elongated products. These results demonstrate different physiological and biochemical responses to primary C18 unsaturated fatty acids in a rat model of human metabolic syndrome.     

Lipid and fatty acid composition of the fat body during the female reproductive cycle of Labidura riparia (Insecta Dermaptera)

During the reproductive cycle of the female Labidura riparia, cytological observations show cyclical modifications of lipid droplets in the periovarian adipocyte. Fat body lipids and their constitutive fatty acids are analyzed. The lipids are predominantly triacylglycerols, which increase after adult ecdysis during vitellogenic and non-vitellogenic periods. Small amounts of diacylglycerols and phospholipids are found. Diacylglycerols increase during vitellogenesis and decrease during the non-vitellogenic period. Cytological modifications of lipid droplets are probably related to diacylglycerol fluctuations. Gas-liquid chromatography of fatty acid methyl esters shows oleic acid to be the predominant fatty acid in total lipids and triacylglycerols; unsaturated acids are approximately twice as abundant as saturated acids all along the reproductive cycle. Fatty acid composition of diacylglycerols and phospholipids differs from triacylglycerols and total lipids composition. Palmitic, stearic, oleic and linoleic acids represent the major fatty acids; their relative amounts vary during the different periods of the reproductive cycle. The correlations between fat body lipid changes and ovarian development were discussed and compared with observations made on other insect species. Accepted: 23 April 1997     

Growth temperature affects accumulation of exogenous fatty acids and fatty acid composition in <Emphasis Type="Italic">Schizosaccharomyces pombe</Emphasis>

The incorporation of exogenously supplied fatty acids, palmitic acid, palmitoleic acid, oleic acid and linoleic acid, was examined in the yeast Schizosaccharomyces pombe at two growth temperatures, 20 °C and 30 °C. Fatty acids supplied to S. pombe in the growth medium were found to be preferentially incorporated into the cells, becoming a dominant species. The relative increase in exogenous fatty acids in cells came at the expense of endogenous oleic acid as a proportion of total fatty acids. Lowering the temperature at which the yeast were grown resulted in decreased levels of incorporation of the fatty acids palmitic acid, palmitoleic acid and linoleic acid compared to cells supplemented at 30 °C. In addition, the relative amount of the endogenously produced unsaturated fatty acid oleic acid, while greatly reduced compared to unsupplemented cells, was increased in cells supplemented with fatty acids at 20 °C compared to supplemented cells at 30 °C. The differential production of oleic acid in S. pombe cells indicates that regulation of unsaturated fatty acid levels, possibly by control of the stearoyl-CoA desaturase, is an important control point in membrane composition in response to temperature and diet in this species.     

Effects of fatty acids on lysis of Streptococcus faecalis.

Palmitic, stearic, oleic, and linoleic acids at concentrations of 200 nmol/ml all inhibited autolysin activity 80% or more in whole cells or cell-free extracts. This concentration of the saturated fatty acids palmitic acid and stearic acid had little or no effect on the growth of whole cells or protoplasts. However, the unsaturated fatty acids oleic acid and linoleic acid induced lysis in both situations. This lytic effect is apparently not related to any uncoupling activity or inhibition of energy catabolism by unsaturated fatty acids. It is concluded that unsaturated fatty acids induce cell and protoplast lysis by acting as more potent membrane destabilizers than saturated fatty acids.     

Multiple Interactions of Unsaturated Fatty Acids with Opiate and Ouabain Binding Sites and β-Adrenergic Sensitive Adenylate Cyclase System

Abstract

The unsaturated fatty acids oleic, linoleic and arachidonic inhibited binding of ligands to the ouabain, opiate, and β-adrenergic plasma membrane receptors. Low concentrations of fatty acids slightly increased the binding of ouabain to its binding sites. The effect of these fatty acids on β-adrenergic sensitive adenylate cyclase was more complex. 0.2–0.3 mM fatty acids increased adenylate cyclase activity, while higher concentrations of arachidonic and linoleic acids, but not oleic acid     

Incorporation of exogenous fatty acids into phospholipids by cultured hamster fibroblasts. Effect of SV40 transformation

In situ incorporation of two saturated (palmitic, 16:0; stearic, 18:0) and three unsaturated fatty acids (oleic, 18:1; linoleic, 18:2; arachidonic, 20:4) into the four major phospholipids, sphingomyelin, PC, PI and PE, was followed. Transformed cells incorporated unsaturated fatty acids more rapidly, whereas no significant differences were found concerning saturated fatty acids. In vitro determination of phospholipid acylation showed that incorporation of coenzyme A-activated forms of two saturated fatty acids (16:0 and 18:0) and one unsaturated fatty acid (18:1) into phospholipids was increased in transformed cells. Comparison of results obtained in situ and in vitro strongly suggests that incorporation of fatty acids into phospholipids in cultured cells is not limited by acyltransferase activities.     

The protective role of dietary unsaturated fatty acids against 2-undecanone-induced pupal mortality and deformity in Helicoverpa zea

As previously reported, the addition of 2-undecanone to the diet of Helicoverpa (Heliothis) zea (Boddie) causes pupal mortality and deformity. These toxic effects are antagonised by the addition of the unsaturated fatty acid linolenic acid to diet, with pupal deformity eliminated and mortality reduced by as much as one-half. Similar results were obtained with two other unsaturated fatty acids, linoleic and oleic acids, but not with saturated stearic acid. These unsaturated fatty acids also increased pupal weight and developmental time. However, measurement of food consumption indicated that the effect of unsaturated fatty acids on pupal mortality is not an artifact of dilution of the fatty acid dietary dosage by an increased body size or of evaporation of 2-undecanone during prolonged larval development.     

Altered membrane free unsaturated fatty acid composition in human colorectal cancer tissue

Polyunsaturated free fatty acids (PUFAs) participate in normal functioning of the cell, particularly in control intracellular cell signalling. As nutritional components they compose a human diet with an indirect promoting influence on tumourogenesis. The PUFAs level depends on the functional state of the membrane. This work is focused on changes only of free unsaturated fatty acids amount (AA – arachidonic acid, LA – linoleic acid, ALA – α-linolenic acid, palmitoleic acid (PA) and oleic acid) in cell membranes of colorectal cancer of pT3 stage, G2 grade without metastasis. Qualitative and quantitative composition of free unsaturated fatty acids in the membrane was determined by high-performance liquid chromatography. It was shown that the malignant transformation was accompanied by a decrease in amount of LA and ALA while arachidonic and oleic acids increased. It is of interest that free AA levels are elevated in colon cancer, as AA is the precursor to biologically active eicosanoids.     

Fatty acid synthesis is a target for antibacterial activity of unsaturated fatty acids

Long-chain unsaturated fatty acids, such as linoleic acid, show antibacterial activity and are the key ingredients of antimicrobial food additives and some antibacterial herbs. However, the precise mechanism for this antimicrobial activity remains unclear. We found that linoleic acid inhibited bacterial enoyl-acyl carrier protein reductase (FabI), an essential component of bacterial fatty acid synthesis, which has served as a promising target for antibacterial drugs. Additional unsaturated fatty acids including palmitoleic acid, oleic acid, linolenic acid, and arachidonic acid also exhibited the inhibition of FabI. However, neither the saturated form (stearic acid) nor the methyl ester of linoleic acid inhibited FabI. These FabI-inhibitory activities of various fatty acids and their derivatives very well correlated with the inhibition of fatty acid biosynthesis using [(14)C] acetate incorporation assay, and importantly, also correlated with antibacterial activity. Furthermore, the supplementation with exogenous fatty acids reversed the antibacterial effect of linoleic acid, which showing that it target fatty acid synthesis. Our data demonstrate for the first time that the antibacterial action of unsaturated fatty acids is mediated by the inhibition of fatty acid synthesis.     

Fatty acids of callus tissues of six species of cucurbitaceae

A comparative study was made of the fatty acid composition of the total lipids extracted from the cotyledons and the callus cultures derived from cotyledon segments of six species of Cucurbitaceae. Conditions for callus induction and growth of cultures were identical. The difference between the two systems was in the reversal of the ratio of total unsaturated to saturated acids in all callus cultures. In callus cultures, instead of linoleic, linolenic was the major unsaturated fatty acid. In Momordica charantia, α-elaeostearic acid present in the cotyledon was not detected in callus and oleic acid was the major unsaturated fatty acid.     

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.     

Unsaturated fatty acids induce mesenchymal stem cells to increase secretion of angiogenic mediators

Mesenchymal stem cells (MSC) represent emerging cell-based therapies for diabetes and associated complications. Ongoing clinical trials are using exogenous MSC to treat type 1 and 2 diabetes, cardiovascular disease and non-healing wounds due to diabetes. The majority of these trials are aimed at exploiting the ability of these multipotent mesenchymal stromal cells to release soluble mediators that reduce inflammation and promote both angiogenesis and cell survival at sites of tissue damage. Growing evidence suggests that MSC secretion of soluble factors is dependent on tissue microenvironment. Despite the contribution of fatty acids to the metabolic environment of type 2 diabetes, almost nothing is known about their effects on MSC secretion of growth factors and cytokines. In this study, human bone marrow-derived MSC were exposed to linoleic acid, an omega-6 polyunsaturated fatty acid, or oleic acid, a monounsaturated fatty acid, for seven days in the presence of 5.38 mM glucose. Outcomes measured included MSC proliferation, gene expression, protein secretion and chemotaxis. Linoleic and oleic acids inhibited MSC proliferation and altered MSC expression and secretion of known mediators of angiogenesis. Both unsaturated fatty acids induced MSC to increase secretion of interleukin-6, VEGF and nitric oxide. In addition, linoleic acid but not oleic acid induced MSC to increase production of interleukin-8. Collectively these data suggest that exposure to fatty acids may have functional consequences for MSC therapy. Fatty acids may affect MSC engraftment to injured tissue and MSC secretion of cytokines and growth factors that regulate local cellular responses to injury.     

Seasonal changes in fatty acid composition associated with cold-hardening in third instar larvae of Eurosta solidaginis

Third-instar larvae of the goldenrod gall fly Eurosta solidaginis (Diptera: Tephritidae) survive extended periods in winter during which tissue water is frozen. Both low temperature and reduced water activity during freezing present challenges for the structural integrity of cellular lipids. Fatty acids of both phospholipids and triacylglycerols from fat body cells of E. solidaginis were analyzed throughout fall and early winter, a period that encompasses the acquisition of freeze-tolerance, to determine if adaptations to freezing include changes in fatty acid unsaturation. The five most abundant fatty acids from both fractions were (in decreasing order) oleic (40–65%), palmitoleic (18–20%), palmitic (12–17%), linoleic (5–10%), and stearic acids (4 –7%). This represents a typical complement of Dipteran fatty acids, although oleic acid levels were higher in E. solidaginis than those reported from other Dipterans (˜28%; Downer 1985). From September to November, monounsaturates increased from 59 to 70% in phospholipids at the expense of saturated fatty acids (25% –20%) suggesting activation of a Δ⁹-desaturase enzyme. These changes resulted in an increase in the ratio of unsaturated to saturated fatty acids (U/S) from 3.0 to 4.2, although there was no change in the average number of double bonds per fatty acid (unsaturation index, UI ≈ 1.2 in phospholipids and 0.9 in triacylglycerols throughout the season). These changes were temporally correlated to decreasing ambient temperatures and increasing larval and fat body cell freeze-tolerance. Accepted: 31 October 1996     

Chemical detection of the proteins and lipids in the fat body cells from workers of Attini ants (Hymenoptera: Formicidae)

The ultrastructural cytochemistry study and the chemical analysis carried out to examine the fat body of workers of the basal Attini Cyphomyrmex rimosus and Mycetarotes parallelus and the derived Acromyrmex disciger and Atta laevigata revealed very electrondense protein granules of varied sizes and shapes distributed throughout the cytoplasm of parietal and perivisceral trophocytes and oenocytes. Lipids were present in the cytoplasm of trophocytes as very electrondense granules. In M. parallelus, A. disciger, and A. laevigata, lipids were present as droplets. In parietal as well as perivisceral oenocytes, lipid granules were very electrondense. In A. laevigata, lipids were present as droplets. The chemical analysis using gas chromatography showed that the main lipid compounds present in trophocytes and oenocytes were saturated (myristic, palmitic, and stearic) and unsaturated fatty acids (oleic and linoleic). Also, in basal species, lipid compounds consisted of mainly saturated fatty acids, while in derived species saturated as well as unsaturated fatty acids were observed.     

Seasonal Changes of Fatty Acid Compositions in Overwintering Larvae of Rice Stem Borer,Chilo suppressalis (Lepidoptera: Pyralidae)

Cold acclimation and overwintering state can affect fatty acid compositions of insects. To determine compositional change of fatty acids during nondiapause and diapause stages, an experiment was conducted to investigate fatty acid constituents from whole body of C. suppressalis larvae. Five most abundant fatty acids were found to be palmitoleic (35–58%), palmitic (18–44%), oleic (14–23%), stearic (0.5–2.5%) and linoleic acid (0.4–2%). However, linolenic, erucic, lauric and myristic acid were found at lower level. Saturated fatty acids significantly decreased and conversely unsaturated fatty acids increased from August (pre-diapause) to October (initiation of diapause). The increase in seasonal cold hardiness during cold acclimation, exposed at −15°C for 24 h, was related to degree of fatty acid unsaturation. The elevation of palmitoleic acid content at low temperature resulted in an increase in the overall degree of unsaturation in the whole body. These results indicated the importance of unsaturated fatty acids composition to prepare larvae entering diapause phase.     

Efficient incorporation of unsaturated fatty acids into volicitin-related compounds in Spodoptera litura (Lepidoptera: Noctuidae)

We introduced efficient incorporation of unsaturated fatty acids into volicitin [N-(17-hydroxylinolenoyl)-L-glutamine] and N-linolenoyl-L-glutamine, insect-derived elicitors of plant volatiles, in the common cutworms Spodoptera litura by the incubation of larval gut tissues with unsaturated (linolenic, linoleic, and oleic acids) or saturated fatty acids (palmitic and stearic acids) sodium salt, and L-[alpha-(15)N]glutamine.     

Inhibition of protein kinase C by H-7 potentiates the release of oleic, linoleic and arachidonic acids in A23187-stimulated human neutrophils

This present report describes the effect of H-7, a protein kinase C inhibitor, on the release of oleic, linoleic and arachidonic acids in A23187-stimulated neutrophils. Surprisingly, the inhibitor potentiated the release of all three unsaturated fatty acids in neutrophils stimulated with A23187 alone. In contrast, released oleic acid, linoleic acid and arachidonic acid in phorbol 12-myristate 13-acetate-primed neutrophils were attenuated by 35, 47 and 33%, respectively, in the presence of H-7 (300 microM). Phorbol 12-myristate 13-acetate (PMA) had no effect on A23187-stimulated release of saturated fatty acids. Both PMA and H-7 when used alone had no effect on the release of saturated or unsaturated fatty acids. We, therefore, conclude that H-7 may have effects other than inhibiting PMA-primed responses including superoxide generation, degranulation and arachidonic acid release in human neutrophils.     

The Occurrence of Renin Inhibitor in Rice: Isolation,Identification, and Structure-Function Relationship

We found renin inhibitory activity in rice. The physico-chemical data on the isolated inhibitors were identical to those of oleic acid and linoleic acid. Oleic acid and linoleic acid competitively inhibited renin activity, with K_i values of 15.8 and 19.8 μM respectively. Other unsaturated free fatty acids also inhibited renin activity, but saturated fatty acids had no effect on it.     

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.